Publications by authors named "Thomas Garcia"

28 Publications

  • Page 1 of 1

De Novo KAT5 Variants Cause a Syndrome with Recognizable Facial Dysmorphisms, Cerebellar Atrophy, Sleep Disturbance, and Epilepsy.

Authors:
Jonathan Humbert Smrithi Salian Periklis Makrythanasis Gabrielle Lemire Justine Rousseau Sophie Ehresmann Thomas Garcia Rami Alasiri Armand Bottani Sylviane Hanquinet Erin Beaver Jennifer Heeley Ann C M Smith Seth I Berger Stylianos E Antonarakis Xiang-Jiao Yang Jacques Côté Philippe M Campeau

Am J Hum Genet 2020 09 20;107(3):564-574. Epub 2020 Aug 20.

Sainte-Justine Hospital Research Center, University of Montreal, Montreal, QC H3T 1C5, Canada. Electronic address:

KAT5 encodes an essential lysine acetyltransferase, previously called TIP60, which is involved in regulating gene expression, DNA repair, chromatin remodeling, apoptosis, and cell proliferation; but it remains unclear whether variants in this gene cause a genetic disease. Here, we study three individuals with heterozygous de novo missense variants in KAT5 that affect normally invariant residues, with one at the chromodomain (p.Arg53His) and two at or near the acetyl-CoA binding site (p.Cys369Ser and p.Ser413Ala). All three individuals have cerebral malformations, seizures, global developmental delay or intellectual disability, and severe sleep disturbance. Progressive cerebellar atrophy was also noted. Histone acetylation assays with purified variant KAT5 demonstrated that the variants decrease or abolish the ability of the resulting NuA4/TIP60 multi-subunit complexes to acetylate the histone H4 tail in chromatin. Transcriptomic analysis in affected individual fibroblasts showed deregulation of multiple genes that control development. Moreover, there was also upregulated expression of PER1 (a key gene involved in circadian control) in agreement with sleep anomalies in all of the individuals. In conclusion, dominant missense KAT5 variants cause histone acetylation deficiency with transcriptional dysregulation of multiples genes, thereby leading to a neurodevelopmental syndrome with sleep disturbance, cerebellar atrophy, and facial dysmorphisms, and suggesting a recognizable syndrome.
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http://dx.doi.org/10.1016/j.ajhg.2020.08.002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7477011PMC
September 2020

Large-scale discovery of male reproductive tract-specific genes through analysis of RNA-seq datasets.

Authors:
Matthew J Robertson Katarzyna Kent Nathan Tharp Kaori Nozawa Laura Dean Michelle Mathew Sandra L Grimm Zhifeng Yu Christine Légaré Yoshitaka Fujihara Masahito Ikawa Robert Sullivan Cristian Coarfa Martin M Matzuk Thomas X Garcia

BMC Biol 2020 08 19;18(1):103. Epub 2020 Aug 19.

Department of Pathology and Immunology, Baylor College of Medicine, 1 Baylor Plaza, Houston, TX, 77030, USA.

Background: The development of a safe, effective, reversible, non-hormonal contraceptive method for men has been an ongoing effort for the past few decades. However, despite significant progress on elucidating the function of key proteins involved in reproduction, understanding male reproductive physiology is limited by incomplete information on the genes expressed in reproductive tissues, and no contraceptive targets have so far reached clinical trials. To advance product development, further identification of novel reproductive tract-specific genes leading to potentially druggable protein targets is imperative.

Results: In this study, we expand on previous single tissue, single species studies by integrating analysis of publicly available human and mouse RNA-seq datasets whose initial published purpose was not focused on identifying male reproductive tract-specific targets. We also incorporate analysis of additional newly acquired human and mouse testis and epididymis samples to increase the number of targets identified. We detected a combined total of 1178 genes for which no previous evidence of male reproductive tract-specific expression was annotated, many of which are potentially druggable targets. Through RT-PCR, we confirmed the reproductive tract-specific expression of 51 novel orthologous human and mouse genes without a reported mouse model. Of these, we ablated four epididymis-specific genes (Spint3, Spint4, Spint5, and Ces5a) and two testis-specific genes (Pp2d1 and Saxo1) in individual or double knockout mice generated through the CRISPR/Cas9 system. Our results validate a functional requirement for Spint4/5 and Ces5a in male mouse fertility, while demonstrating that Spint3, Pp2d1, and Saxo1 are each individually dispensable for male mouse fertility.

Conclusions: Our work provides a plethora of novel testis- and epididymis-specific genes and elucidates the functional requirement of several of these genes, which is essential towards understanding the etiology of male infertility and the development of male contraceptives.
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http://dx.doi.org/10.1186/s12915-020-00826-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7436996PMC
August 2020

CRISPR/Cas9-based genome editing in mice uncovers 13 testis- or epididymis-enriched genes individually dispensable for male reproduction†.

Authors:
Jiang Sun Yonggang Lu Kaori Nozawa Zoulan Xu Akane Morohoshi Julio M Castaneda Taichi Noda Haruhiko Miyata Ferheen Abbasi Hossam H Shawki Satoru Takahashi Darius J Devlin Zhifeng Yu Ryan M Matzuk Thomas X Garcia Martin M Matzuk Masahito Ikawa

Biol Reprod 2020 08;103(2):183-194

Department of Experimental Genome Research, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka, Japan.

Developing a safe and effective male contraceptive remains a challenge in the field of medical science. Molecules that selectively target the male reproductive tract and whose targets are indispensable for male reproductive function serve among the best candidates for a novel non-hormonal male contraceptive method. To determine the function of these genes in vivo, mutant mice carrying disrupted testis- or epididymis-enriched genes were generated by zygote microinjection or electroporation of the CRISPR/Cas9 components. Male fecundity was determined by consecutively pairing knockout males with wild-type females and comparing the fecundity of wild-type controls. Phenotypic analyses of testis appearance and weight, testis and epididymis histology, and sperm movement were further carried out to examine any potential spermatogenic or sperm maturation defect in mutant males. In this study, we uncovered 13 testis- or epididymis-enriched evolutionarily conserved genes that are individually dispensable for male fertility in mice. Owing to their dispensable nature, it is not feasible to use these targets for the development of a male contraceptive.
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http://dx.doi.org/10.1093/biolre/ioaa083DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7401351PMC
August 2020

CRISPR/Cas9-mediated genome-edited mice reveal 10 testis-enriched genes are dispensable for male fecundity.

Authors:
Soojin Park Keisuke Shimada Yoshitaka Fujihara Zoulan Xu Kentaro Shimada Tamara Larasati Putri Pratiwi Ryan M Matzuk Darius J Devlin Zhifeng Yu Thomas X Garcia Martin M Matzuk Masahito Ikawa

Biol Reprod 2020 08;103(2):195-204

Graduate School of Medicine, Osaka University, Osaka, Japan.

As the world population continues to increase to unsustainable levels, the importance of birth control and the development of new contraceptives are emerging. To date, male contraceptive options have been lagging behind those available to women, and those few options available are not satisfactory to everyone. To solve this problem, we have been searching for new candidate target proteins for non-hormonal contraceptives. Testis-specific proteins are appealing targets for male contraceptives because they are more likely to be involved in male reproduction and their targeting by small molecules is predicted to have no on-target harmful effects on other organs. Using in silico analysis, we identified Erich2, Glt6d1, Prss58, Slfnl1, Sppl2c, Stpg3, Tex33, and Tex36 as testis-abundant genes in both mouse and human. The genes, 4930402F06Rik and 4930568D16Rik, are testis-abundant paralogs of Glt6d1 that we also discovered in mice but not in human, and were also included in our studies to eliminate the potential compensation. We generated knockout (KO) mouse lines of all listed genes using the CRISPR/Cas9 system. Analysis of all of the individual KO mouse lines as well as Glt6d1/4930402F06Rik/4930568D16Rik TKO mouse lines revealed that they are male fertile with no observable defects in reproductive organs, suggesting that these 10 genes are not required for male fertility nor play redundant roles in the case of the 3 Glt6D1 paralogs. Further studies are needed to uncover protein function(s), but in vivo functional screening using the CRISPR/Cas9 system is a fast and accurate way to find genes essential for male fertility, which may apply to studies of genes expressed elsewhere. In this study, although we could not find any potential protein targets for non-hormonal male contraceptives, our findings help to streamline efforts to find and focus on only the essential genes.
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http://dx.doi.org/10.1093/biolre/ioaa084DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7401030PMC
August 2020

Toward Development of the Male Pill: A Decade of Potential Non-hormonal Contraceptive Targets.

Authors:
Katarzyna Kent Madelaine Johnston Natasha Strump Thomas X Garcia

Front Cell Dev Biol 2020 26;8:61. Epub 2020 Feb 26.

Department of Pathology & Immunology, Baylor College of Medicine, Houston, TX, United States.

With the continued steep rise of the global human population, and the paucity of safe and practical contraceptive options available to men, the need for development of effective and reversible non-hormonal methods of male fertility control is widely recognized. Currently there are several contraceptive options available to men, however, none of the non-hormonal alternatives have been clinically approved. To advance progress in the development of a safe and reversible contraceptive for men, further identification of novel reproductive tract-specific druggable protein targets is required. Here we provide an overview of genes/proteins identified in the last decade as specific or highly expressed in the male reproductive tract, with deletion phenotypes leading to complete male infertility in mice. These phenotypes include arrest of spermatogenesis and/or spermiogenesis, abnormal spermiation, abnormal spermatid morphology, abnormal sperm motility, azoospermia, globozoospermia, asthenozoospermia, and/or teratozoospermia, which are all desirable outcomes for a novel male contraceptive. We also consider other associated deletion phenotypes that could impact the desirability of a potential contraceptive. We further discuss novel contraceptive targets underscoring promising leads with the objective of presenting data for potential druggability and whether collateral effects may exist from paralogs with close sequence similarity.
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http://dx.doi.org/10.3389/fcell.2020.00061DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7054227PMC
February 2020

The testis-specific serine proteases PRSS44, PRSS46, and PRSS54 are dispensable for male mouse fertility†.

Authors:
Richard J Holcomb Seiya Oura Kaori Nozawa Katarzyna Kent Zhifeng Yu Matthew J Robertson Cristian Coarfa Martin M Matzuk Masahito Ikawa Thomas X Garcia

Biol Reprod 2020 02;102(1):84-91

Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX, USA.

High-throughput transcriptomics and proteomics approaches have recently identified a large number of germ cell-specific genes with many that remain to be studied through functional genetics approaches. Serine proteases (PRSS) constitute nearly one-third of all proteases, and, in our bioinformatics screens, we identified many that are testis specific. In this study, we chose to focus on Prss44, Prss46, and Prss54, which we confirmed as testis specific in mouse and human. Based on the analysis of developmental expression in the mouse, expression of all four genes is restricted to the late stage of spermatogenesis concomitant with a potential functional role in spermiogenesis, spermiation, or sperm function. To best understand the male reproductive requirement and functional roles of these serine proteases, each gene was individually ablated by CRISPR/Cas9-mediated ES cell or zygote approach. Homozygous deletion mutants for each gene were obtained and analyzed for phenotypic changes. Analyses of testis weights, testis and epididymis histology, sperm morphology, and fertility revealed no significant differences in Prss44, Prss46, and Prss54 knockout mice in comparison to controls. Our results thereby demonstrate that these genes are not required for normal fertility in mice, although do not preclude the possibility that these genes may function in a redundant manner. Elucidating the individual functional requirement or lack thereof of these novel genes is necessary to build a better understanding of the factors underlying spermatogenesis and sperm maturation, which has implications in understanding the etiology of male infertility and the development of male contraceptives.
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http://dx.doi.org/10.1093/biolre/ioz158DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7013879PMC
February 2020

CRISPR/Cas9-mediated genome editing reveals 30 testis-enriched genes dispensable for male fertility in mice†.

Authors:
Yonggang Lu Seiya Oura Takafumi Matsumura Asami Oji Nobuyuki Sakurai Yoshitaka Fujihara Keisuke Shimada Haruhiko Miyata Tomohiro Tobita Taichi Noda Julio M Castaneda Daiji Kiyozumi Qian Zhang Tamara Larasati Samantha A M Young Mayo Kodani Caitlin A Huddleston Matthew J Robertson Cristian Coarfa Ayako Isotani R John Aitken Masaru Okabe Martin M Matzuk Thomas X Garcia Masahito Ikawa

Biol Reprod 2019 08;101(2):501-511

Department of Experimental Genome Research, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka, Japan.

More than 1000 genes are predicted to be predominantly expressed in mouse testis, yet many of them remain unstudied in terms of their roles in spermatogenesis and sperm function and their essentiality in male reproduction. Since individually indispensable factors can provide important implications for the diagnosis of genetically related idiopathic male infertility and may serve as candidate targets for the development of nonhormonal male contraceptives, our laboratories continuously analyze the functions of testis-enriched genes in vivo by generating knockout mouse lines using the CRISPR/Cas9 system. The dispensability of genes in male reproduction is easily determined by examining the fecundity of knockout males. During our large-scale screening of essential factors, we knocked out 30 genes that have a strong bias of expression in the testis and are mostly conserved in mammalian species including human. Fertility tests reveal that the mutant males exhibited normal fecundity, suggesting these genes are individually dispensable for male reproduction. Since such functionally redundant genes are of diminished biological and clinical significance, we believe that it is crucial to disseminate this list of genes, along with their phenotypic information, to the scientific community to avoid unnecessary expenditure of time and research funds and duplication of efforts by other laboratories.
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http://dx.doi.org/10.1093/biolre/ioz103DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6735960PMC
August 2019

Undifferentiated spermatogonia regulate expression through NOTCH signaling and drive germ cell differentiation.

Authors:
Parag A Parekh Thomas X Garcia Reham Waheeb Vivek Jain Pooja Gandhi Marvin L Meistrich Gunapala Shetty Marie-Claude Hofmann

FASEB J 2019 07 16;33(7):8423-8435. Epub 2019 Apr 16.

Department of Endocrine Neoplasia and Hormonal Disorders, University of Texas M. D. Anderson Cancer Center, Houston, Texas, USA.

Cytochrome P450 family 26 subfamily B member 1 (CYP26B1) regulates the concentration of all-trans retinoic acid (RA) and plays a key role in germ cell differentiation by controlling local distribution of RA. The mechanisms regulating expression in postnatal Sertoli cells, the main components of the stem cell niche, are so far unknown. During gonad development, expression of is maintained by Steroidogenic Factor 1 (SF-1) and Sex-Determining Region Y Box-9 (SOX9), which ensure that RA is degraded and germ cell differentiation is blocked. Here, we show that the NOTCH target Hairy/Enhancer-of-Split Related with YRPW Motif 1 (HEY1), a transcriptional repressor, regulates germ cell differentiation direct binding to the promoter and thus inhibits its expression in Sertoli cells. Further, using germ cell ablation, we demonstrate that undifferentiated type A spermatogonia are the cells that activate NOTCH signaling in Sertoli cells through their expression of the NOTCH ligand JAGGED-1 (JAG1) at stage VIII of the seminiferous epithelium cycle, therefore mediating germ cell differentiation by a ligand concentration-dependent process. These data therefore provide more insights into the mechanisms of germ cell differentiation after birth and potentially explain the spatiotemporal RA pulses driving the transition between undifferentiated to differentiating spermatogonia.-Parekh, P. A., Garcia, T. X., Waheeb, R., Jain, V., Gandhi, P., Meistrich, M. L., Shetty, G., Hofmann, M.-C. Undifferentiated spermatogonia regulate expression through NOTCH signaling and drive germ cell differentiation.
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http://dx.doi.org/10.1096/fj.201802361RDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6593872PMC
July 2019

Combined small molecule and loss-of-function screen uncovers estrogen receptor alpha and CAD as host factors for HDV infection and antiviral targets.

Authors:
Eloi R Verrier Amélie Weiss Charlotte Bach Laura Heydmann Vincent Turon-Lagot Arnaud Kopp Houssein El Saghire Emilie Crouchet Patrick Pessaux Thomas Garcia Patrick Pale Mirjam B Zeisel Camille Sureau Catherine Schuster Laurent Brino Thomas F Baumert

Gut 2020 01 4;69(1):158-167. Epub 2019 Mar 4.

Université de Strasbourg, Inserm, Institut de Recherche sur les Maladies Virales et Hépatiques UMR_S1110, F-67000 Strasbourg, France.

Objective: Hepatitis D virus (HDV) is a circular RNA virus coinfecting hepatocytes with hepatitis B virus. Chronic hepatitis D results in severe liver disease and an increased risk of liver cancer. Efficient therapeutic approaches against HDV are absent.

Design: Here, we combined an RNAi loss-of-function and small molecule screen to uncover host-dependency factors for HDV infection.

Results: Functional screening unravelled the hypoxia-inducible factor (HIF)-signalling and insulin-resistance pathways, RNA polymerase II, glycosaminoglycan biosynthesis and the pyrimidine metabolism as virus-hepatocyte dependency networks. Validation studies in primary human hepatocytes identified the carbamoyl-phosphatesynthetase 2, aspartate transcarbamylase and dihydroorotase (CAD) enzyme and estrogen receptor alpha (encoded by ) as key host factors for HDV life cycle. Mechanistic studies revealed that the two host factors are required for viral replication. Inhibition studies using N-(phosphonoacetyl)-L-aspartic acid and fulvestrant, specific CAD and ESR1 inhibitors, respectively, uncovered their impact as antiviral targets.

Conclusion: The discovery of HDV host-dependency factors elucidates the pathogenesis of viral disease biology and opens therapeutic strategies for HDV cure.
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http://dx.doi.org/10.1136/gutjnl-2018-317065DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6943243PMC
January 2020

Missense Variants in the Histone Acetyltransferase Complex Component Gene TRRAP Cause Autism and Syndromic Intellectual Disability.

Authors:
Benjamin Cogné Sophie Ehresmann Eliane Beauregard-Lacroix Justine Rousseau Thomas Besnard Thomas Garcia Slavé Petrovski Shiri Avni Kirsty McWalter Patrick R Blackburn Stephan J Sanders Kévin Uguen Jacqueline Harris Julie S Cohen Moira Blyth Anna Lehman Jonathan Berg Mindy H Li Usha Kini Shelagh Joss Charlotte von der Lippe Christopher T Gordon Jennifer B Humberson Laurie Robak Daryl A Scott Vernon R Sutton Cara M Skraban Jennifer J Johnston Annapurna Poduri Magnus Nordenskjöld Vandana Shashi Erica H Gerkes Ernie M H F Bongers Christian Gilissen Yuri A Zarate Malin Kvarnung Kevin P Lally Peggy A Kulch Brina Daniels Andres Hernandez-Garcia Nicholas Stong Julie McGaughran Kyle Retterer Kristian Tveten Jennifer Sullivan Madeleine R Geisheker Asbjorg Stray-Pedersen Jennifer M Tarpinian Eric W Klee Julie C Sapp Jacob Zyskind Øystein L Holla Emma Bedoukian Francesca Filippini Anne Guimier Arnaud Picard Øyvind L Busk Jaya Punetha Rolph Pfundt Anna Lindstrand Ann Nordgren Fayth Kalb Megha Desai Ashley Harmon Ebanks Shalini N Jhangiani Tammie Dewan Zeynep H Coban Akdemir Aida Telegrafi Elaine H Zackai Amber Begtrup Xiaofei Song Annick Toutain Ingrid M Wentzensen Sylvie Odent Dominique Bonneau Xénia Latypova Wallid Deb Sylvia Redon Frédéric Bilan Marine Legendre Caitlin Troyer Kerri Whitlock Oana Caluseriu Marine I Murphree Pavel N Pichurin Katherine Agre Ralitza Gavrilova Tuula Rinne Meredith Park Catherine Shain Erin L Heinzen Rui Xiao Jeanne Amiel Stanislas Lyonnet Bertrand Isidor Leslie G Biesecker Dan Lowenstein Jennifer E Posey Anne-Sophie Denommé-Pichon Claude Férec Xiang-Jiao Yang Jill A Rosenfeld Brigitte Gilbert-Dussardier Séverine Audebert-Bellanger Richard Redon Holly A F Stessman Christoffer Nellaker Yaping Yang James R Lupski David B Goldstein Evan E Eichler Francois Bolduc Stéphane Bézieau Sébastien Küry Philippe M Campeau

Am J Hum Genet 2019 03 28;104(3):530-541. Epub 2019 Feb 28.

Centre Hospitalier Universitaire Sainte-Justine Research Centre, University of Montreal, Montreal, QC H3T 1C5, Canada; Department of Pediatrics, University of Montreal, Montreal, QC H3T1J4, Canada. Electronic address:

Acetylation of the lysine residues in histones and other DNA-binding proteins plays a major role in regulation of eukaryotic gene expression. This process is controlled by histone acetyltransferases (HATs/KATs) found in multiprotein complexes that are recruited to chromatin by the scaffolding subunit transformation/transcription domain-associated protein (TRRAP). TRRAP is evolutionarily conserved and is among the top five genes intolerant to missense variation. Through an international collaboration, 17 distinct de novo or apparently de novo variants were identified in TRRAP in 24 individuals. A strong genotype-phenotype correlation was observed with two distinct clinical spectra. The first is a complex, multi-systemic syndrome associated with various malformations of the brain, heart, kidneys, and genitourinary system and characterized by a wide range of intellectual functioning; a number of affected individuals have intellectual disability (ID) and markedly impaired basic life functions. Individuals with this phenotype had missense variants clustering around the c.3127G>A p.(Ala1043Thr) variant identified in five individuals. The second spectrum manifested with autism spectrum disorder (ASD) and/or ID and epilepsy. Facial dysmorphism was seen in both groups and included upslanted palpebral fissures, epicanthus, telecanthus, a wide nasal bridge and ridge, a broad and smooth philtrum, and a thin upper lip. RNA sequencing analysis of skin fibroblasts derived from affected individuals skin fibroblasts showed significant changes in the expression of several genes implicated in neuronal function and ion transport. Thus, we describe here the clinical spectrum associated with TRRAP pathogenic missense variants, and we suggest a genotype-phenotype correlation useful for clinical evaluation of the pathogenicity of the variants.
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http://dx.doi.org/10.1016/j.ajhg.2019.01.010DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6407527PMC
March 2019

Regulation of GDNF expression in Sertoli cells.

Authors:
Parag A Parekh Thomas X Garcia Marie-Claude Hofmann

Reproduction 2019 03;157(3):R95-R107

Department of Endocrine Neoplasia, UT MD Anderson Cancer Center, Houston, Texas, USA.

Sertoli cells regulate male germ cell proliferation and differentiation and are a critical component of the spermatogonial stem cell (SSC) niche, where homeostasis is maintained by the interplay of several signaling pathways and growth factors. These factors are secreted by Sertoli cells located within the seminiferous epithelium, and by interstitial cells residing between the seminiferous tubules. Sertoli cells and peritubular myoid cells produce glial cell line-derived neurotrophic factor (GDNF), which binds to the RET/GFRA1 receptor complex at the surface of undifferentiated spermatogonia. GDNF is known for its ability to drive SSC self-renewal and proliferation of their direct cell progeny. Even though the effects of GDNF are well studied, our understanding of the regulation its expression is still limited. The purpose of this review is to discuss how GDNF expression in Sertoli cells is modulated within the niche, and how these mechanisms impact germ cell homeostasis.
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http://dx.doi.org/10.1530/REP-18-0239DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6602878PMC
March 2019

Expanding the Spectrum of BAF-Related Disorders: De Novo Variants in SMARCC2 Cause a Syndrome with Intellectual Disability and Developmental Delay.

Authors:
Keren Machol Justine Rousseau Sophie Ehresmann Thomas Garcia Thi Tuyet Mai Nguyen Rebecca C Spillmann Jennifer A Sullivan Vandana Shashi Yong-Hui Jiang Nicholas Stong Elise Fiala Marcia Willing Rolph Pfundt Tjitske Kleefstra Megan T Cho Heather McLaughlin Monica Rosello Piera Carmen Orellana Francisco Martínez Alfonso Caro-Llopis Sandra Monfort Tony Roscioli Cheng Yee Nixon Michael F Buckley Anne Turner Wendy D Jones Peter M van Hasselt Floris C Hofstede Koen L I van Gassen Alice S Brooks Marjon A van Slegtenhorst Katherine Lachlan Jessica Sebastian Suneeta Madan-Khetarpal Desai Sonal Naidu Sakkubai Julien Thevenon Laurence Faivre Alice Maurel Slavé Petrovski Ian D Krantz Jennifer M Tarpinian Jill A Rosenfeld Brendan H Lee Philippe M Campeau

Am J Hum Genet 2019 01 20;104(1):164-178. Epub 2018 Dec 20.

Department of Pediatrics, CHU Sainte-Justine Research Center and University of Montreal, Montreal, QC H3T 1C5, Canada. Electronic address:

SMARCC2 (BAF170) is one of the invariable core subunits of the ATP-dependent chromatin remodeling BAF (BRG1-associated factor) complex and plays a crucial role in embryogenesis and corticogenesis. Pathogenic variants in genes encoding other components of the BAF complex have been associated with intellectual disability syndromes. Despite its significant biological role, variants in SMARCC2 have not been directly associated with human disease previously. Using whole-exome sequencing and a web-based gene-matching program, we identified 15 individuals with variable degrees of neurodevelopmental delay and growth retardation harboring one of 13 heterozygous variants in SMARCC2, most of them novel and proven de novo. The clinical presentation overlaps with intellectual disability syndromes associated with other BAF subunits, such as Coffin-Siris and Nicolaides-Baraitser syndromes and includes prominent speech impairment, hypotonia, feeding difficulties, behavioral abnormalities, and dysmorphic features such as hypertrichosis, thick eyebrows, thin upper lip vermilion, and upturned nose. Nine out of the fifteen individuals harbor variants in the highly conserved SMARCC2 DNA-interacting domains (SANT and SWIRM) and present with a more severe phenotype. Two of these individuals present cardiac abnormalities. Transcriptomic analysis of fibroblasts from affected individuals highlights a group of differentially expressed genes with possible roles in regulation of neuronal development and function, namely H19, SCRG1, RELN, and CACNB4. Our findings suggest a novel SMARCC2-related syndrome that overlaps with neurodevelopmental disorders associated with variants in BAF-complex subunits.
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http://dx.doi.org/10.1016/j.ajhg.2018.11.007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6323608PMC
January 2019

MetaboRank: network-based recommendation system to interpret and enrich metabolomics results.

Authors:
Clément Frainay Sandrine Aros Maxime Chazalviel Thomas Garcia Florence Vinson Nicolas Weiss Benoit Colsch Frédéric Sedel Dominique Thabut Christophe Junot Fabien Jourdan

Bioinformatics 2019 01;35(2):274-283

Toxalim, Université de Toulouse, INRA, Université de Toulouse 3 Paul Sabatier, Toulouse, France.

Motivation: Metabolomics has shown great potential to improve the understanding of complex diseases, potentially leading to therapeutic target identification. However, no single analytical method allows monitoring all metabolites in a sample, resulting in incomplete metabolic fingerprints. This incompleteness constitutes a stumbling block to interpretation, raising the need for methods that can enrich those fingerprints. We propose MetaboRank, a new solution inspired by social network recommendation systems for the identification of metabolites potentially related to a metabolic fingerprint.

Results: MetaboRank method had been used to enrich metabolomics data obtained on cerebrospinal fluid samples from patients suffering from hepatic encephalopathy (HE). MetaboRank successfully recommended metabolites not present in the original fingerprint. The quality of recommendations was evaluated by using literature automatic search, in order to check that recommended metabolites could be related to the disease. Complementary mass spectrometry experiments and raw data analysis were performed to confirm these suggestions. In particular, MetaboRank recommended the overlooked α-ketoglutaramate as a metabolite which should be added to the metabolic fingerprint of HE, thus suggesting that metabolic fingerprints enhancement can provide new insight on complex diseases.

Availability And Implementation: Method is implemented in the MetExplore server and is available at www.metexplore.fr. A tutorial is available at https://metexplore.toulouse.inra.fr/com/tutorials/MetaboRank/2017-MetaboRank.pdf.

Supplementary Information: Supplementary data are available at Bioinformatics online.
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http://dx.doi.org/10.1093/bioinformatics/bty577DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6330003PMC
January 2019

The NOTCH Ligand JAG1 Regulates GDNF Expression in Sertoli Cells.

Authors:
Thomas X Garcia Parag Parekh Pooja Gandhi Krishna Sinha Marie-Claude Hofmann

Stem Cells Dev 2017 04 3;26(8):585-598. Epub 2017 Jan 3.

1 Department of Endocrine Neoplasia and Hormonal Disorders, University of Texas, MD Anderson Cancer Center , Houston, Texas.

In the seminiferous epithelium of the testis, Sertoli cells are key niche cells directing proliferation and differentiation of spermatogonial stem cells (SSCs) into spermatozoa. Sertoli cells produce glial cell line-derived neurotrophic factor (GDNF), which is essential for SSC self-renewal and progenitor expansion. While the role of GDNF in the testis stem cell niche is established, little is known about how this factor is regulated. Our previous studies on NOTCH activity in Sertoli cells demonstrated a role of this pathway in limiting stem/progenitor cell numbers, thus ultimately downregulating sperm cell output. In this study we demonstrate through a double-mutant mouse model that NOTCH signaling in Sertoli cells functions solely through the canonical pathway. Further, we demonstrate through Dual luciferase assay and chromatin immunoprecipitation quantitative polymerase chain reaction (ChIP-qPCR) analysis that the NOTCH targets HES1 and HEY1, which are transcriptional repressors, directly downregulate GDNF expression by binding to the Gdnf promoter, thus antagonizing the effects of FSH/cAMP. Finally, we demonstrate that testicular stem/progenitors cells are activating NOTCH signaling in Sertoli cells in vivo and in vitro through the NOTCH ligand JAG1 at their surface, indicating that these cells may ensure their own homeostasis through negative feedback regulation.
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http://dx.doi.org/10.1089/scd.2016.0318DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5393414PMC
April 2017

The evolution of adhesiveness as a social adaptation.

Authors:
Thomas Garcia Guilhem Doulcier Silvia De Monte

Elife 2015 Nov 27;4. Epub 2015 Nov 27.

Institut de Biologie de l'École Normale Supérieure, École Normale Supérieure, PSL Research University, Paris, France.

Cellular adhesion is a key ingredient to sustain collective functions of microbial aggregates. Here, we investigate the evolutionary origins of adhesion and the emergence of groups of genealogically unrelated cells with a game-theoretical model. The considered adhesiveness trait is costly, continuous and affects both group formation and group-derived benefits. The formalism of adaptive dynamics reveals two evolutionary stable strategies, at each extreme on the axis of adhesiveness. We show that cohesive groups can evolve by small mutational steps, provided the population is already endowed with a minimum adhesiveness level. Assortment between more adhesive types, and in particular differential propensities to leave a fraction of individuals ungrouped at the end of the aggregation process, can compensate for the cost of increased adhesiveness. We also discuss the change in the social nature of more adhesive mutations along evolutionary trajectories, and find that altruism arises before directly beneficial behavior, despite being the most challenging form of cooperation.
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http://dx.doi.org/10.7554/eLife.08595DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4775229PMC
November 2015

RBPJ in mouse Sertoli cells is required for proper regulation of the testis stem cell niche.

Authors:
Thomas Xavier Garcia Jaspreet Kaur Farmaha Sean Kow Marie-Claude Hofmann

Development 2014 Dec 18;141(23):4468-78. Epub 2014 Nov 18.

Department of Endocrine Neoplasia and Hormonal Disorders, The University of Texas MD Anderson Cancer Center, Unit 1105, PO Box 301402, Houston, TX 77230-1402, USA Department of Comparative Biosciences, University of Illinois at Urbana-Champaign, Urbana, IL 61802, USA

Stem cells are influenced by their surrounding microenvironment, or niche. In the testis, Sertoli cells are the key niche cells directing the population size and differentiation fate of spermatogonial stem cells (SSCs). Failure to properly regulate SSCs leads to infertility or germ cell hyperplasia. Several Sertoli cell-expressed genes, such as Gdnf and Cyp26b1, have been identified as being indispensable for the proper maintenance of SSCs in their niche, but the pathways that modulate their expression have not been identified. Although we have recently found that constitutively activating NOTCH signaling in Sertoli cells leads to premature differentiation of all prospermatogonia and sterility, suggesting that there is a crucial role for this pathway in the testis stem cell niche, a true physiological function of NOTCH signaling in Sertoli cells has not been demonstrated. To this end, we conditionally ablated recombination signal binding protein for immunoglobulin kappa J region (Rbpj), a crucial mediator of NOTCH signaling, in Sertoli cells using Amh-cre. Rbpj knockout mice had: significantly increased testis sizes; increased expression of niche factors, such as Gdnf and Cyp26b1; significant increases in the number of pre- and post-meiotic germ cells, including SSCs; and, in a significant proportion of mice, testicular failure and atrophy with tubule lithiasis, possibly due to these unsustainable increases in the number of germ cells. We also identified germ cells as the NOTCH ligand-expressing cells. We conclude that NOTCH signaling in Sertoli cells is required for proper regulation of the testis stem cell niche and is a potential feedback mechanism, based on germ cell input, that governs the expression of factors that control SSC proliferation and differentiation.
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http://dx.doi.org/10.1242/dev.113969DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4302926PMC
December 2014

Differential adhesion between moving particles as a mechanism for the evolution of social groups.

Authors:
Thomas Garcia Leonardo Gregory Brunnet Silvia De Monte

PLoS Comput Biol 2014 Feb 27;10(2):e1003482. Epub 2014 Feb 27.

CNRS UMR 8197 INSERM U1024, Institut de Biologie de l'École Normale Supérieure (IBENS), Paris, France.

The evolutionary stability of cooperative traits, that are beneficial to other individuals but costly to their carrier, is considered possible only through the establishment of a sufficient degree of assortment between cooperators. Chimeric microbial populations, characterized by simple interactions between unrelated individuals, restrain the applicability of standard mechanisms generating such assortment, in particular when cells disperse between successive reproductive events such as happens in Dicyostelids and Myxobacteria. In this paper, we address the evolutionary dynamics of a costly trait that enhances attachment to others as well as group cohesion. By modeling cells as self-propelled particles moving on a plane according to local interaction forces and undergoing cycles of aggregation, reproduction and dispersal, we show that blind differential adhesion provides a basis for assortment in the process of group formation. When reproductive performance depends on the social context of players, evolution by natural selection can lead to the success of the social trait, and to the concomitant emergence of sizeable groups. We point out the conditions on the microscopic properties of motion and interaction that make such evolutionary outcome possible, stressing that the advent of sociality by differential adhesion is restricted to specific ecological contexts. Moreover, we show that the aggregation process naturally implies the existence of non-aggregated particles, and highlight their crucial evolutionary role despite being largely neglected in theoretical models for the evolution of sociality.
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http://dx.doi.org/10.1371/journal.pcbi.1003482DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3937110PMC
February 2014

Sub-acute intravenous administration of silver nanoparticles in male mice alters Leydig cell function and testosterone levels.

Authors:
Thomas X Garcia Guilherme M J Costa Luiz R França Marie-Claude Hofmann

Reprod Toxicol 2014 Jun 18;45:59-70. Epub 2014 Jan 18.

Department of Comparative Biosciences, University of Illinois at Urbana-Champaign, Urbana, IL 61802, USA; Department of Endocrine Neoplasia and Hormonal Disorders, The University of Texas MD Anderson Cancer Center, Houston, TX, USA. Electronic address:

The aim of this study was to determine whether short-term, in vivo exposure to silver nanoparticles (AgNPs) could be toxic to male reproduction. Low dose (1mg/kg/dose) AgNPs were intravenously injected into male CD1 mice over 12 days. Treatment resulted in no changes in body and testis weights, sperm concentration and motility, fertility indices, or follicle-stimulating hormone and luteinizing hormone serum concentrations; however, serum and intratesticular testosterone concentrations were significantly increased 15 days after initial treatment. Histologic evaluation revealed significant changes in epithelium morphology, germ cell apoptosis, and Leydig cell size. Additionally, gene expression analysis revealed Cyp11a1 and Hsd3b1 mRNA significantly upregulated in treated animals. These data suggest that AgNPs do not impair spermatogonial stem cells in vivo since treatment did not result in significant decreases in testis weight and sperm concentrations. However, AgNPs appear to affect Leydig cell function, yielding increasing testicular and serum testosterone levels.
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http://dx.doi.org/10.1016/j.reprotox.2014.01.006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4309383PMC
June 2014

NOTCH signaling in Sertoli cells regulates gonocyte fate.

Authors:
Thomas Xavier Garcia Marie-Claude Hofmann

Cell Cycle 2013 Aug 10;12(16):2538-45. Epub 2013 Jul 10.

Department of Endocrine Neoplasia and Hormonal Disorders, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.

Gonocytes (or prospermatogonia) are the precursors to spermatogonial stem cells (SSCs), which provide the foundation for spermatogenesis through their ability to both self-renew and generate daughter cells. Despite their relative importance, the regulatory mechanisms that govern gonocyte maintenance and transition to SSCs are poorly understood. Recently, we reported that constitutive activation of NOTCH1 signaling in Sertoli cells causes gonocyte exit from quiescence--the first suggestion of the potential role of this signaling pathway in the testis. This Extra View will review what is known about NOTCH signaling, particularly in Sertoli cells and germ cells in the testes, by providing a background on germ cell biology and a summary of our recently published data on NOTCH1 signaling in Sertoli cells. We also describe additional data showing that aberrant proliferation and differentiation of gonocytes in response to constitutive activation of NOTCH1 signaling in Sertoli cells involves de novo expression of cell cycle proteins and a marked upregulation of the KIT receptor. These data further suggest that NOTCH signaling orchestrates a dynamic balance between maintenance and differentiation of gonocytes in the perinatal testis.
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http://dx.doi.org/10.4161/cc.25627DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3865042PMC
August 2013

Constitutive activation of NOTCH1 signaling in Sertoli cells causes gonocyte exit from quiescence.

Authors:
Thomas Xavier Garcia Tony DeFalco Blanche Capel Marie-Claude Hofmann

Dev Biol 2013 May 4;377(1):188-201. Epub 2013 Feb 4.

Department of Comparative Biosciences, University of Illinois at Urbana-Champaign, Urbana, IL 61802, USA.

Notch signaling components have long been detected in Sertoli and germ cells in the developing and mature testis. However, the role of this pathway in testis development and spermatogenesis remains unknown. Using reporter mice expressing green fluorescent protein following Notch receptor activation, we found that Notch signaling was active in Sertoli cells at various fetal, neonatal, and adult stages. Since Notch signaling specifies stem cell fate in many developing and mature organ systems, we hypothesized that maintenance and differentiation of gonocytes and/or spermatogonial stem cells would be modulated through this pathway in Sertoli cells. To this end, we generated mutant mice constitutively expressing the active, intracellular domain of NOTCH1 (NICD1) in Sertoli cells. We found that mutant Sertoli cells were morphologically normal before and after birth, but presented a number of functional changes that drastically affected gonocyte numbers and physiology. We observed aberrant exit of gonocytes from mitotic arrest, migration toward cord periphery, and premature differentiation before birth. These events, presumably unsupported by the cellular microenvironment, were followed by gonocyte apoptosis and near complete disappearance of the gonocytes by day 2 after birth. Molecular analysis demonstrated that these effects are correlated with a dysregulation of Sertoli-expressed genes that are required for germ cell maintenance, such as Cyp26b1 and Gdnf. Taken together, our results demonstrate that Notch signaling is active in Sertoli cells throughout development and that proper regulation of Notch signaling in Sertoli cells is required for the maintenance of gonocytes in an undifferentiated state during fetal development.
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http://dx.doi.org/10.1016/j.ydbio.2013.01.031DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3630254PMC
May 2013

Group formation and the evolution of sociality.

Authors:
Thomas Garcia Silvia De Monte

Evolution 2013 Jan 10;67(1):131-41. Epub 2012 Aug 10.

École Normale Supérieure, Unité Mixte de Recherche 7625, Écologie et Évolution, 46 rue d'Ulm, 75005 Paris, France.

In spite of its intrinsic evolutionary instability, altruistic behavior in social groups is widespread in nature, spanning from organisms endowed with complex cognitive abilities to microbial populations. In this study, we show that if social individuals have an enhanced tendency to form groups and fitness increases with group cohesion, sociality can evolve and be maintained in the absence of actively assortative mechanisms such as kin recognition or nepotism toward other carriers of the social gene. When explicitly taken into account in a game-theoretical framework, the process of group formation qualitatively changes the evolutionary dynamics with respect to games played in groups of constant size and equal grouping tendencies. The evolutionary consequences of the rules underpinning the group size distribution are discussed for a simple model of microbial aggregation by differential attachment, indicating a way to the evolution of sociality bereft of peer recognition.
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http://dx.doi.org/10.1111/j.1558-5646.2012.01739.xDOI Listing
January 2013

Isolation of undifferentiated and early differentiating type A spermatogonia from Pou5f1-GFP reporter mice.

Authors:
Thomas Garcia Marie-Claude Hofmann

Methods Mol Biol 2012 ;825:31-44

Department of Comparative Biosciences, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, IL, USA.

Limited understanding of the mechanisms underlying self-renewal and differentiation of spermatogonial stem cells hampers our ability to develop new therapeutic and contraceptive approaches. Mouse models of spermatogonial stem cell development are key to developing new insights into the biology of both the normal and diseased testis. Advances in transgenic reporter mice have enabled the isolation, molecular characterization, and functional analysis of mouse Type A spermatogonia subpopulations from the normal testis, including populations enriched for spermatogonial stem cells. Application of these reporters both to the normal testis and to gene-deficient and over-expression models will promote a better understanding of the earliest steps of spermatogenesis, and the role of spermatogonial stem cells in germ cell tumor.
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http://dx.doi.org/10.1007/978-1-61779-436-0_3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3314309PMC
April 2012

ETV5 regulates sertoli cell chemokines involved in mouse stem/progenitor spermatogonia maintenance.

Authors:
Liz Simon Gail C Ekman Thomas Garcia Kay Carnes Zhen Zhang Theresa Murphy Kenneth M Murphy Rex A Hess Paul S Cooke Marie-Claude Hofmann

Stem Cells 2010 Oct;28(10):1882-92

Department of Veterinary Biosciences, University of Illinois, Urbana, Illinois 61802, USA.

Spermatogonial stem cells are the only stem cells in the body that transmit genetic information to offspring. Although growth factors responsible for self-renewal of these cells are known, the factors and mechanisms that attract and physically maintain these cells within their microenvironment are poorly understood. Mice with targeted disruption of Ets variant gene 5 (Etv5) show total loss of stem/progenitor spermatogonia following the first wave of spermatogenesis, resulting in a Sertoli cell-only phenotype and aspermia. Microarray analysis of primary Sertoli cells from Etv5 knockout (Etv5(-/-)) versus wild-type (WT) mice revealed significant decreases in expression of several chemokines. Chemotaxis assays demonstrated that migration of stem/progenitor spermatogonia toward Etv5(-/-) Sertoli cells was significantly decreased compared to migration toward WT Sertoli cells. Interestingly, differentiating spermatogonia, spermatocytes, and round spermatids were not chemoattracted by WT Sertoli cells, whereas stem/progenitor spermatogonia showed a high and significant chemotactic index. Rescue assays using recombinant chemokines indicated that C-C-motif ligand 9 (CCL9) facilitates Sertoli cell chemoattraction of stem/progenitor spermatogonia, which express C-C-receptor type 1 (CCR1). In addition, there is protein-DNA interaction between ETV5 and Ccl9, suggesting that ETV5 might be a direct regulator of Ccl9 expression. Taken together, our data show for the first time that Sertoli cells are chemoattractive for stem/progenitor spermatogonia, and that production of specific chemokines is regulated by ETV5. Therefore, changes in chemokine production and consequent decreases in chemoattraction by Etv5(-/-) Sertoli cells helps to explain stem/progenitor spermatogonia loss in Etv5(-/-) mice.
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http://dx.doi.org/10.1002/stem.508DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3109872PMC
October 2010

A critical GxxxA motif in the gamma6 calcium channel subunit mediates its inhibitory effect on Cav3.1 calcium current.

Authors:
Zuojun Lin Katja Witschas Thomas Garcia Ren-Shiang Chen Jared P Hansen Zachary M Sellers Elza Kuzmenkina Stefan Herzig Philip M Best

J Physiol 2008 Nov 25;586(22):5349-66. Epub 2008 Sep 25.

Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.

The eight members of the calcium channel gamma subunit family are integral membrane proteins that regulate the expression and behaviour of voltage and ligand gated ion channels. While a subgroup consisting of gamma(2), gamma(3), gamma(4) and gamma(8) (the TARPs) modulate AMPA receptor localization and function, the gamma(1) and gamma(6) subunits conform to the original description of these proteins as regulators of voltage gated calcium channels. We have previously shown that the gamma(6) subunit is highly expressed in atrial myocytes and that it is capable of acting as a negative modulator of low voltage activated calcium current. In this study we extend our understanding of gamma(6) subunit modulation of low voltage activated calcium current. Using engineered chimeric constructs, we demonstrate that the first transmembrane domain (TM1) of gamma(6) is necessary for its inhibitory effect on Cav3.1 current. Mutational analysis is then used to identify a unique GxxxA motif within TM1 that is required for the function of the subunit strongly suggesting the involvement of helix-helix interactions in its effects. Results from co-immunoprecipitation experiments confirm a physical association of gamma(6) with the Cav3.1 channel in both HEK cells and atrial myocytes. Single channel analysis reveals that binding of gamma(6) reduces channel availability for activation. Taken together, the results of this study provide both a molecular and a mechanistic framework for understanding the unique ability of the gamma(6) calcium channel subunit to modulate low voltage activated (Cav3.1) calcium current density.
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http://dx.doi.org/10.1113/jphysiol.2008.159111DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2655381PMC
November 2008

Calcium channel gamma subunits: a functionally diverse protein family.

Authors:
Ren-Shiang Chen Tzyy-Chyn Deng Thomas Garcia Zachary M Sellers Philip M Best

Cell Biochem Biophys 2007 ;47(2):178-86

Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, 524 Burrill Hall, 407 S Goodwin Avenue, Urbana, IL 61801, USA.

The calcium channel gamma subunits comprise an eight-member protein family that share a common topology consisting of four transmembrane domains and intracellular N- and C-termini. Although the first gamma subunit was identified as an auxiliary subunit of a voltage-dependent calcium channel, a review of phylogenetic, bioinformatic, and functional studies indicates that they are a functionally diverse protein family. A cluster containing gamma1 and gamma6 conforms to the original description of the protein family as they seem to act primarily as subunits of calcium channels expressed in muscle. Members of a second cluster (gamma2, gamma3, gamma4, gamma8) function as regulators of AMPA receptor localization and function in the brain and are collectively known as TARPs. The function of members of the third cluster (gamma5, gamma7) remains unclear. Our analysis shows that the members of each cluster contain conserved regulatory motifs that help to differentiate the groups. However, the physiological significance of these motifs in many cases remains to be demonstrated.
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http://dx.doi.org/10.1007/s12013-007-0002-0DOI Listing
October 2007

A pilot study of quantitative aspiration in patients with symptoms of obstructive sleep apnea: comparison to a historic control group.

Authors:
Michael Beal Andrew Chesson Thomas Garcia Gloria Caldito Fred Stucker Cherie-Ann Nathan

Laryngoscope 2004 Jun;114(6):965-8

Department of Otolaryngology, Louisiana State University Health Sciences Center, Shreveport, LA, USA.

Objective: It has been shown that many healthy people aspirate secretions at night. Patients with obstructive sleep apnea (OSA) have frequent episodes of gasping at night that may predispose them to aspiration. The purpose of this study was to determine whether patients with symptoms of OSA are predisposed to pharyngeal aspiration.

Study Design: A prospective study in which patients with symptoms of OSA were compared with a historic group of normal controls by using the same methodology.

Methods: The study was offered to patients with symptoms of OSA undergoing a sleep study. The radiotracer Technicium was infused through a plastic tube placed in the nasopharynx after the patient achieved stage II sleep. A chest radionuclide scan determined the amount of material aspirated. The Wilcoxon-rank sum test was used to compare the mean amount aspirated between the experimental and historic control groups.

Results: Fourteen patients successfully completed the study. One normal volunteer in our study aspirated a quantity similar to the historic normal control group. The amount of aspirated material in the study group ranged from 0.152 to 3.648 mL, with a mean of 1.24 mL +/- 0.905 (SD). When compared with the historic normal control group, the patients with symptoms of OSA aspirated significantly more radio-tracer (P <.01). There was a lack of association between respiratory disturbance index and amount aspirated.

Conclusions: The results suggest there is an apparent risk of increased pharyngeal aspiration in patients with symptoms of OSA.
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http://dx.doi.org/10.1097/00005537-200406000-00002DOI Listing
June 2004

Results of statistical analysis of blend and dosage unit content uniformity data obtained from the Product Quality Research Institute Blend Uniformity Working Group data-mining effort.

Authors:
Garth Boehm Jon Clark John Dietrick Laura Foust Thomas Garcia Muralidhara Gavini Jean-Marie Geoffroy Pedro Jimenez Gerald Mergen Fernando Muzzio Jerry Planchard James Prescott Jozef Timmermans Neeru Takiar David Whiteman

PDA J Pharm Sci Technol 2004 Mar-Apr;58(2):62-74

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October 2004

The use of stratefied sampling of blend and dosage units to demonstrate adequacy of mix for powder blends.

Authors:
Garth Boehm Jon Clark John Dietrick Laura Foust Thomas Garcia Muralidhara Gavini Loren Gelber Jean-Marie Geoffroy Jack Hoblitzell Pedro Jimenez Gerald Mergen Fernando Muzzio Jerry Planchard James Prescott Jozef Timmermans Neeru Takiar

PDA J Pharm Sci Technol 2003 Mar-Apr;57(2):64-74

Faulding, Inc.

In response to concerns expressed by applicants regarding inconsistent policies in establishing blend uniformity acceptance criteria to demonstrate adequacy of mix, the FDA Office of Generic Drugs (OGD) issued the draft document Guidance for Industry, ANDAs: Blend Uniformity Analysis (August 1999). Both generic and innovator pharmaceutical companies raised a number of concerns following the publication of this document. As a result, the Product Quality Research Institute (PQRI) Blend Uniformity Working Group (BUWG) was established in February 2000. One of the primary goals of this group was to draft a scientifically based alternative to the OGD document. The resulting recommendation addresses both FDA and industry concerns by substantially enhancing product quality assurance without increasing regulatory burden. The PQRI BUWG recommends that these blend and dosage unit uniformity requirements be administered uniformly throughout the industry. PQRI submitted the following recommendation to the FDA on December 31, 2002, providing the Agency with an alternative strategy to consider when drafting future regulatory policy to assess blend and dosage unit uniformity.
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February 2004