Publications by authors named "Bassam Abomoelak"

15 Publications

  • Page 1 of 1

Efficacy of Short Course of Preksha Dhyana for Functional Abdominal Pain Disorder in a Busy Pediatric Clinic.

Front Pediatr 2021 25;9:646686. Epub 2021 May 25.

Department of Pediatric Gastroenterology and Nutrition, Orlando Health-Arnold Palmer Hospital for Children, Orlando, FL, United States.

Mind body techniques such as meditation improve symptoms in children and adults with IBS. Typical courses, however, are lengthy and difficult to administer. We report our experience with a short course of (PD), a child-friendly focused meditation with yoga. Physicians deliver focused meditation while medical assistants taught yoga. Three sessions were administered biweekly with recommendations for daily practice. Pain severity Likert scores were compared with a treatment as usual (TAU) historical control. Anxiety scores were compared from baseline in the PD group. Thirty PD patients aged 9-17 (20 female) and 52 consecutive TAU group aged 5-17 (33 female) were reviewed. The biweekly sessions had high (71%) completion rates. Utilization rates of PD were similar to TAU despite added sessions. The PD group had an average time of follow-up of 8.9 ± 9.4 vs. 6.0 ± 3.9 months in the TAU group ( = 0.522). Changes in pain scores from baseline showed improvement in the PD group, 0.67 ± 0.13 vs. TAU 1.39 ± 0.11 ( = 0.0003). In the PD group, anxiety scores improved significantly from baseline (0.5 vs. 1, < 0.001). Pain improved in 93% (28/30) and resolved in 47% (14/30). A short course of PD was successfully embedded in a busy pediatric office without additional staffing. The approach proved cost-effective without increasing overall healthcare utilization and showed significant benefits over TAU. Pending RCT confirmation, this offers a cost-effective method to incorporate mind-body techniques into a pediatric office practice.
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http://dx.doi.org/10.3389/fped.2021.646686DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8185299PMC
May 2021

Effects of Combining Meditation Techniques on Short-Term Memory, Attention, and Affect in Healthy College Students.

Front Psychol 2021 5;12:607573. Epub 2021 Mar 5.

Gastrointestinal Translational Laboratory, Arnold Palmer Hospital for Children, Orlando, FL, United States.

Meditation refers to a family of self-regulation practices that focuses on training attention and awareness to foster psycho-emotional well-being and to develop specific capacities such as calmness, clarity, and concentration. We report a prospective convenience-controlled study in which we analyzed the effect of two components of - buzzing bee sound meditation () and color meditation () on healthy college students. and are two practices that are based on sound and green color, respectively. The study population represents a suitable target as college students experience different stress factors during the school year. This study measures the individual and combined effects of two techniques (one focusing on sound and one focusing on color), on short-term memory, attention, and affect, in novice meditators. We used a battery of cognitive, performance, and compared results with baseline and control values. We found improved cognition, especially attention, short-term memory, and affect in terms of positivity and reduced negativity. Overall, the two techniques produced variable benefits and subjects showed improved scores over baseline for short-term memory, cognitive function, and overall wellbeing. Further studies are required to understand underlying mechanisms for the observed differences between the two techniques and to elucidate mechanisms underlying the more pronounced and global benefits observed with the combined techniques. These results underscore a need to examine individual components of meditation practices in order to individualize treatment approaches for attention disorders in young adults. ClinicalTrials.gov Identifier: NCT03779269.
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http://dx.doi.org/10.3389/fpsyg.2021.607573DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7973112PMC
March 2021

Pulmonary Microbiome of Patients Receiving Mechanical Ventilation: Changes Over Time.

Am J Crit Care 2021 03;30(2):128-132

Devendra Mehta is a pediatric gastroenterologist, Pediatric Specialty Diagnostic Laboratory, Arnold Palmer Hospital, Orlando, Florida.

Background: Interest in the pulmonary microbiome is growing, particularly in patients undergoing mechanical ventilation.

Objectives: To explore the pulmonary microbiome over time in patients undergoing prolonged mechanical ventilation and to evaluate the effect of an oral suctioning intervention on the microbiome.

Methods: This descriptive subanalysis from a clinical trial involved a random sample of 16 participants (7 intervention, 9 control) who received mechanical ventilation for at least 5 days. Five paired oral and tracheal specimens were evaluated for each participant over time. Bacterial DNA from the paired specimens was evaluated using 16S rRNA gene sequencing. Bacterial taxonomy composition, α-diversity (Shannon index), and β-diversity (Morisita-Horn index) were calculated and compared within and between participants.

Results: Participants were predominantly male (69%) and White (63%), with a mean age of 58 years, and underwent mechanical ventilation for a mean of 9.36 days. Abundant bacterial taxa included Prevotella, Staphylococcus, Streptococcus, Stenotrophomonas, and Veillonella. Mean tracheal α-diversity decreased over time for the total group (P = .002) and the control group (P = .02). β-Diversity was lower (P = .04) in the control group (1.905) than in the intervention group (2.607).

Conclusions: Prolonged mechanical ventilation was associated with changes in the pulmonary microbiome, with the control group having less diversity. The oral suctioning intervention may have reduced oral-tracheal bacterial transmission.
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http://dx.doi.org/10.4037/ajcc2021194DOI Listing
March 2021

Intubation Setting, Aspiration, and Ventilator-Associated Conditions.

Am J Crit Care 2020 09;29(5):371-378

Mary Lou Sole is dean, Orlando Health Endowed Chair in Nursing, and University of Central Florida Pegasus Professor, University of Central Florida College of Nursing.

Background: Patients experience endotracheal intubation in various settings with wide-ranging risks for postintubation complications such as aspiration and ventilator-associated conditions.

Objectives: To evaluate associations between intubation setting, presence of aspiration biomarkers, and clinical outcomes.

Methods: This study is a subanalysis of data from the NO-ASPIRATE single-blinded randomized clinical trial. Data were prospectively collected for 513 adult patients intubated within 24 hours of enrollment. Patients with documented aspiration events at intubation were excluded. In the NO-ASPIRATE trial, intervention patients received enhanced oropharyngeal suctioning every 4 hours and control patients received sham suctioning. Tracheal specimens for α-amylase and pepsin tests were collected upon enrollment. Primary outcomes were ventilator hours, lengths of stay, and rates of ventilator-associated conditions.

Results: Of the baseline tracheal specimens, 76.4% were positive for α-amylase and 33.1% were positive for pepsin. Proportions of positive tracheal α-amylase and pepsin tests did not differ significantly between intubation locations (study hospital, transfer from other hospital, or field intubation). No differences were found for ventilator hours or lengths of stay. Patients intubated at another hospital and transferred had significantly higher ventilator-associated condition rates than did those intubated at the study hospital (P = .02). Ventilator-associated condition rates did not differ significantly between patients intubated in the field and patients in other groups.

Conclusions: Higher ventilator-associated condition rates associated with interhospital transfer may be related to movement from bed, vehicle loading and unloading, and transport vehicle vibrations. Airway assessment and care may also be suboptimal in the transport environment.
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http://dx.doi.org/10.4037/ajcc2020129DOI Listing
September 2020

Sucrase-isomaltase Gene Variants in Patients With Abnormal Sucrase Activity and Functional Gastrointestinal Disorders.

J Pediatr Gastroenterol Nutr 2021 01;72(1):29-35

Gastroenterology Translational Research Division, Arnold Palmer Hospital Specialty Diagnostic Laboratory.

Objectives: The aim of the study was to determine prevalence and characterize sucrase-isomaltase (SI) gene variants of congenital sucrase-isomaltase deficiency in non-Hispanic white pediatric and young adult patients with functional gastrointestinal disorders (FGIDs), and abnormal sucrase activity on histologically normal duodenal biopsy.

Methods: Clinical symptoms and disaccharidase activities data were collected for an abnormal (low) sucrase (≤25.8 U, n = 125) activity group, and 2 normal sucrase activity groups with moderate (≥25.8-≤55 U, n = 250) and high (>55 U, n = 250) sucrase activities. SI gene variants were detected by next-generation sequencing of DNA from formalin-fixed paraffin-embedded tissues of these patients. FGIDs symptoms based on Rome IV criteria and subsequent clinical management of abnormal sucrase activity cases with pathogenic SI gene variants were analyzed.

Results: Thirteen SI gene variants were found to be significantly higher in abnormal sucrase cases with FGIDs symptoms (36/125, 29%; 71% did not have a pathogenic variant) compared to moderate normal (16/250, 6.4%, P < 0.001) or high normal (5/250, 2.0%, P < 0.001) sucrase groups. Clinical management data were available in 26 of abnormal sucrase cases, and only 10 (38%) were correctly diagnosed and managed by the clinicians. Concomitant lactase deficiency (24%; 23/97) and pan-disaccharidase deficiency (25%; 13/51) were found in the abnormal sucrase group.

Conclusions: Heterozygous and compound heterozygous mutations in the SI gene were more prevalent in cases with abnormal sucrase activity presenting with FGIDs, and normal histopathology. This suggests heterozygous pathogenic variants of congenital sucrase-isomaltase deficiency may present as FGIDs. Concomitant lactase or pan-disaccharidase deficiencies were common in abnormal sucrase cases with SI gene variants.
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http://dx.doi.org/10.1097/MPG.0000000000002852DOI Listing
January 2021

Impact of deep oropharyngeal suctioning on microaspiration, ventilator events, and clinical outcomes: A randomized clinical trial.

J Adv Nurs 2019 Nov 7;75(11):3045-3057. Epub 2019 Aug 7.

Pediatric Specialty Diagnostic Laboratory, Arnold Palmer Hospital, Orlando Health, Orlando, Florida.

Aims: To evaluate a deep oropharyngeal suction intervention (NO-ASPIRATE) in intubated patients on microaspiration, ventilator-associated events and clinical outcomes.

Design: Prospective, two-group, single-blind, randomized clinical trial.

Methods: The study was conducted between 2014 - 2017 in 513 participants enroled within 24 hr of intubation and randomized into NO-ASPIRATE or usual care groups. Standard oral care was provided to all participants every 4 hr and deep oropharyngeal suctioning was added to the NO-ASPIRATE group. Oral and tracheal specimens were obtained to quantify α-amylase as an aspiration biomarker.

Results: Data were analysed for 410 study completers enrolled at least 36 hr: NO-ASPIRATE (N = 206) and usual care (N = 204). Percent of tracheal specimens positive for α-amylase, mean tracheal α-amylase levels over time and ventilator-associated events were not different between groups. The NO-ASPIRATE group had a shorter hospital length of stay and a subgroup with moderate aspiration at baseline had significantly lower α-amylase levels across time.

Conclusion: Hospital length of stay was shorter in the NO-ASPIRATE group and a subgroup of intervention participants had lower α-amylase across time. Delivery of standardized oral care to all participants may have been an intervention itself and possibly associated with the lack of significant findings for most outcomes.

Impact: This trial compared usual care to oral care with a deep suctioning intervention on microaspiration and ventilator-associated events, as this has not been systematically studied. Further research on the usefulness of α-amylase as an aspiration biomarker and the role of oral suctioning, especially for certain populations, is indicated.

Trial Registration Number: ClinicalTrials.gov: NCT02284178.
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http://dx.doi.org/10.1111/jan.14142DOI Listing
November 2019

Developmental cigarette smoke exposure: hippocampus proteome and metabolome profiles in low birth weight pups.

Toxicology 2014 Mar 28;317:40-9. Epub 2014 Jan 28.

Department of Molecular, Cellular, and Craniofacial Biology, ULSD, University of Louisville, Louisville, KY, USA; Birth Defects Center, University of Louisville, Louisville, KY, USA.

Exposure to cigarette smoke during development is linked to neurodevelopmental delays and cognitive impairment including impulsivity, attention deficit disorder, and lower IQ. However, brain region specific biomolecular alterations induced by developmental cigarette smoke exposure (CSE) remain largely unexplored. In the current molecular phenotyping study, a mouse model of 'active' developmental CSE (serum cotinine > 50 ng/mL) spanning pre-implantation through third trimester-equivalent brain development (gestational day (GD) 1 through postnatal day (PD) 21) was utilized. Hippocampus tissue collected at the time of cessation of exposure was processed for gel-based proteomic and non-targeted metabolomic profiling with partial least squares-discriminant analysis (PLS-DA) for selection of features of interest. Ingenuity pathway analysis was utilized to identify candidate molecular and metabolic pathways impacted within the hippocampus. CSE impacted glycolysis, oxidative phosphorylation, fatty acid metabolism, and neurodevelopment pathways within the developing hippocampus.
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http://dx.doi.org/10.1016/j.tox.2014.01.006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4067966PMC
March 2014

Characterization of a novel heat shock protein (Hsp22.5) involved in the pathogenesis of Mycobacterium tuberculosis.

J Bacteriol 2011 Jul 20;193(14):3497-505. Epub 2011 May 20.

Department of Pathobiological Sciences, University of Wisconsin-Madison, 1656 Linden Drive, Madison, Wisconsin 53706-1581, USA.

Tuberculosis is a worldwide health problem, given that one-third of the world's population is currently infected with Mycobacterium tuberculosis. Understanding the regulation of virulence on the molecular level will provide a better understanding of how M. tuberculosis can establish chronic infection. Using in vivo microarray analysis (IVMA), we previously identified a group of genes that are activated in BALB/c mouse lungs compared to in vitro cultures, including the rv0990c gene. Our analysis indicated that this gene is a member of the heat shock regulon and was activated under other stress conditions, including survival in macrophages or during the late phase of chronic tuberculosis in the murine lungs. Deletion of rv0990c from the genome of M. tuberculosis strain H37Rv affected the transcriptional profiles of many genes (n = 382) and operons involved in mycobacterial survival, including the dormancy regulon, ATP synthesis, respiration, protein synthesis, and lipid metabolism. Comparison of the proteomes of the mutant to those of the wild-type strain further confirmed the differential expression of 15 proteins, especially those involved in the heat shock response (e.g., DnaK and GrpE). Finally, the rv0990c mutant strain showed survival equivalent to that of the isogenic wild-type strain during active tuberculosis in guinea pigs, despite showing significant attenuation in BALB/c mice during the chronic phase of the disease. Overall, we suggest that rv0990c encodes a heat shock protein that plays an important role in mycobacterial virulence. Hence, we renamed rv0990c heat shock protein 22.5 (hsp22.5), reflecting its molecular mass.
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http://dx.doi.org/10.1128/JB.01536-10DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3133320PMC
July 2011

CtpV: a putative copper exporter required for full virulence of Mycobacterium tuberculosis.

Mol Microbiol 2010 Sep;77(5):1096-110

Department of Pathobiological Sciences, University of Wisconsin-Madison, 1656 Linden Drive, Madison, WI 53706, USA.

Copper is a required micronutrient that is also toxic at excess concentrations. Currently, little is known about the role of copper in interactions between bacterial pathogens and their human hosts. In this study, we elucidate a mechanism for copper homeostasis in the human pathogen Mycobacterium tuberculosis via characterization of a putative copper exporter, CtpV. CtpV was shown to be required by M. tuberculosis to maintain resistance to copper toxicity. Furthermore, the deletion of ctpV resulted in a 98-gene transcriptional response, which elucidates the increased stress experienced by the bacteria in the absence of this detoxification mechanism. Interestingly, although the ΔctpV mutant survives close to the wild-type levels in both murine and guinea pig models of tuberculosis, animals infected with the ΔctpV mutant displayed decreased lung damage, and mutant-infected mice had a reduced immune response to the bacteria as well as a significant increase in survival time relative to mice infected with wild-type M. tuberculosis. Overall, our study provides the first evidence for a connection between bacterial copper response and the virulence of M. tuberculosis, supporting the hypothesis that copper response could be important to intracellular pathogens, in general.
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http://dx.doi.org/10.1111/j.1365-2958.2010.07273.xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2965804PMC
September 2010

Transcriptional profiling of mycobacterium tuberculosis during infection: lessons learned.

Front Microbiol 2010 18;1:121. Epub 2010 Nov 18.

Department of Pathobiological Sciences, University of Wisconsin-Madison Madison, WI, USA.

Infection with Mycobacterium tuberculosis, the causative agent of tuberculosis, is considered one of the biggest infectious disease killers worldwide. A significant amount of attention has been directed toward revealing genes involved in the virulence and pathogenesis of this air-born pathogen. With the advances in technologies for transcriptional profiling, several groups, including ours, took advantage of DNA microarrays to identify transcriptional units differentially regulated by M. tuberculosis within a host. The main idea behind this approach is that pathogens tend to regulate their gene expression levels depending on the host microenvironment, and preferentially express those needed for survival. Identifying this class of genes will improve our understanding of pathogenesis. In our case, we identified an in vivo expressed genomic island that was preferentially active in murine lungs during early infection, as well as groups of genes active during chronic tuberculosis. Other studies have identified additional gene groups that are active during macrophage infection and even in human lungs. Despite all of these findings, one of the lingering questions remaining was whether in vivo expressed transcripts are relevant to the virulence, pathogenesis, and persistence of the organism. The work of our group and others addressed this question by examining the contribution of in vivo expressed genes using a strategy based on gene deletions followed by animal infections. Overall, the analysis of most of the in vivo expressed genes supported a role of these genes in M. tuberculosis pathogenesis. Further, these data suggest that in vivo transcriptional profiling is a valid approach to identify genes required for bacterial pathogenesis.
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http://dx.doi.org/10.3389/fmicb.2010.00121DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3125582PMC
July 2011

mosR, a novel transcriptional regulator of hypoxia and virulence in Mycobacterium tuberculosis.

J Bacteriol 2009 Oct 31;191(19):5941-52. Epub 2009 Jul 31.

Department of Pathobiological Sciences, University of Wisconsin-Madison, Madison, WI 53706, USA.

Latent tuberculosis represents a high-risk burden for one-third of the world population. Previous analysis of murine tuberculosis identified a novel transcriptional regulator encoded by Rv0348 that could control the establishment of persistent tuberculosis. Disruption of the Rv0348 gene from the genome of the virulent H37Rv strain of Mycobacterium tuberculosis revealed a global impact on the transcriptional profiles of 163 genes, including induction of the mammalian cell entry (mce1) operon and the repression of a significant number of genes involved in hypoxia and starvation responses. Nonetheless, gel shift assays did not reveal direct binding between Rv0348 and a set of regulated promoters, suggesting an indirect regulatory role. However, when expressed in Mycobacterium smegmatis, the Rv0348 transcripts were significantly responsive to different levels of hypoxia and the encoded protein was shown to regulate genes involved in hypoxia [e.g., Rv3130c (tgs1)] and intracellular survival (e.g., mce1), among other genes. Interestingly, the colonization level of the DeltamosR mutant strain was significantly lower than that of the wild-type strain of M. tuberculosis, suggesting its attenuation in the murine model of tuberculosis. Taken together, our analyses indicated that the Rv0348 gene encodes a novel transcriptional factor that regulates several operons involved in mycobacterial survival, especially during hypoxia; hence, we propose that Rv0348 be renamed mosR for regulator of mycobacterial operons of survival.
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http://dx.doi.org/10.1128/JB.00778-09DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2747884PMC
October 2009

A novel in vitro multiple-stress dormancy model for Mycobacterium tuberculosis generates a lipid-loaded, drug-tolerant, dormant pathogen.

PLoS One 2009 Jun 29;4(6):e6077. Epub 2009 Jun 29.

Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL, USA.

Background: Mycobacterium tuberculosis (Mtb) becomes dormant and phenotypically drug resistant when it encounters multiple stresses within the host. Inability of currently available drugs to kill latent Mtb is a major impediment to curing and possibly eradicating tuberculosis (TB). Most in vitro dormancy models, using single stress factors, fail to generate a truly dormant Mtb population. An in vitro model that generates truly dormant Mtb cells is needed to elucidate the metabolic requirements that allow Mtb to successfully go through dormancy, identify new drug targets, and to screen drug candidates to discover novel drugs that can kill dormant pathogen.

Methodology/principal Findings: We developed a novel in vitro multiple-stress dormancy model for Mtb by applying combined stresses of low oxygen (5%), high CO(2) (10%), low nutrient (10% Dubos medium) and acidic pH (5.0), conditions Mtb is thought to encounter in the host. Under this condition, Mtb stopped replicating, lost acid-fastness, accumulated triacylglycerol (TG) and wax ester (WE), and concomitantly acquired phenotypic antibiotic-resistance. Putative neutral lipid biosynthetic genes were up-regulated. These genes may serve as potential targets for new antilatency drugs. The triacylglycerol synthase1 (tgs1) deletion mutant, with impaired ability to accumulate TG, exhibited a lesser degree of antibiotic tolerance and complementation restored antibiotic tolerance. Transcriptome analysis with microarray revealed the achievement of dormant state showing repression of energy generation, transcription and translation machineries and induction of stress-responsive genes. We adapted this model for drug screening using the Alamar Blue dye to quantify the antibiotic tolerant dormant cells.

Conclusions/significance: The new in vitro multiple stress dormancy model efficiently generates Mtb cells meeting all criteria of dormancy, and this method is adaptable to high-throughput screening for drugs that can kill dormant Mtb. A critical link between storage-lipid accumulation and development of phenotypic drug-resistance in Mtb was established. Storage lipid biosynthetic genes may be appropriate targets for novel drugs that can kill latent Mtb.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0006077PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2698117PMC
June 2009

Identification of a diacylglycerol acyltransferase gene involved in accumulation of triacylglycerol in Mycobacterium tuberculosis under stress.

Microbiology (Reading) 2006 Sep;152(Pt 9):2717-2725

Biomolecular Science Center, and Department of Molecular Biology and Microbiology, Burnett College of Biomedical Sciences, University of Central Florida, Orlando, FL 32816-2364, USA.

Mycobacterium tuberculosis under stress stores triacylglycerol (TG). There are 15 genes in M. tuberculosis that belong to a novel family of TG synthase genes (tgs), but it is not known which of them is responsible for this accumulation of TG. In this paper, it is reported that M. tuberculosis H37Rv accumulated TG under acidic, static or hypoxic growth conditions, or upon treatment with NO, whereas TG accumulation was drastically reduced in the tgs1 (Rv3130c) disrupted mutant. Complementation with tgs1 restored this TG accumulation. C(26) was a major fatty acid in this TG, indicating that the TGS1 gene product uses C(26) fatty acid, which is known to be produced by the mycobacterial fatty acid synthase. TGS1 expressed in Escherichia coli preferred C(26 : 0)-CoA for TG synthesis. If TG storage is needed for the long-term survival of M. tuberculosis under dormant conditions, the tgs1 product could be a suitable target for antilatency drugs.
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http://dx.doi.org/10.1099/mic.0.28993-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1575465PMC
September 2006

A novel lipase belonging to the hormone-sensitive lipase family induced under starvation to utilize stored triacylglycerol in Mycobacterium tuberculosis.

J Biol Chem 2006 Feb 13;281(7):3866-75. Epub 2005 Dec 13.

Burnett College of Biomedical Sciences, University of Central Florida, Orlando, 32816, USA.

Twenty-four putative lipase/esterase genes of Mycobacterium tuberculosis H37Rv were expressed in Escherichia coli and assayed for long-chain triacylglycerol (TG) hydrolase activity. We show here that the product of Rv3097c (LIPY) hydrolyzed long-chain TG with high specific activity. LIPY was purified after solubilization from inclusion bodies; the enzyme displayed a K(m) of 7.57 mM and V(max) of 653.3 nmol/mg/min for triolein with optimal activity between pH 8.0 and pH 9.0. LIPY was inhibited by active serine-directed reagents and was inactivated at temperatures above 37 degrees C. Detergents above their critical micellar concentrations and divalent cations inhibited the activity of LIPY. The N-terminal half of LIPY showed sequence homology with the proline glutamic acid-polymorphic GC-rich repetitive sequences protein family of M. tuberculosis. The C-terminal half of LIPY possesses amino acid domains homologous with the hormone-sensitive lipase family and the conserved active-site motif GDSAG. LIPY shows low sequence identity with the annotated lipases of M. tuberculosis and with other bacterial lipases. We demonstrate that hypoxic cultures of M. tuberculosis, which had accumulated TG, hydrolyzed the stored TG when subjected to nutrient starvation. Under such conditions, lipY was induced more than all lipases, suggesting a central role for it in the utilization of stored TG. We also show that in the lipY-deficient mutant, TG utilization was drastically decreased under nutrient-deprived condition. Thus, LIPY may be responsible for the utilization of stored TG during dormancy and reactivation of the pathogen.
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http://dx.doi.org/10.1074/jbc.M505556200DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1523426PMC
February 2006

Induction of a novel class of diacylglycerol acyltransferases and triacylglycerol accumulation in Mycobacterium tuberculosis as it goes into a dormancy-like state in culture.

J Bacteriol 2004 Aug;186(15):5017-30

University of Central Florida, Biomolecular Science Center, BMS 136, 4000 Central Florida Blvd., Orlando, FL 32816-2364, USA.

Mycobacterium tuberculosis enters the host by inhalation of an infectious aerosol and replicates in the alveolar macrophages until the host's immune defense causes bacteriostasis, which leads the pathogen to go into nonreplicative drug-resistant dormancy. The dormant pathogen can survive for decades till the host's immune system is weakened and active tuberculosis develops. Even though fatty acids are thought to be the major energy source required for the persistence phase, the source of fatty acids used is not known. We postulate that the pathogen uses triacylglycerol (TG) as a storage form of fatty acids. Little is known about the biosynthesis of TG in M. tuberculosis. We show that 15 mycobacterial genes that we identified as putative triacylglycerol synthase (tgs) when expressed in Escherichia coli showed TGS activity, and we report some basic catalytic characteristics of the most active enzymes. We show that several tgs genes are induced when the pathogen goes into the nonreplicative drug-resistant state caused by slow withdrawal of O(2) and also by NO treatment, which is known to induce dormancy-associated genes. The gene (Rv3130c) that shows the highest TGS activity when expressed in E. coli shows the highest induction by hypoxia and NO treatment. Biochemical evidence shows that TG synthesis and accumulation occur under both conditions. We conclude that TG may be a form of energy storage for use during long-term dormancy. Therefore, TG synthesis may be an appropriate target for novel antilatency drugs that can prevent the organism from surviving dormancy and thus assist in the control of tuberculosis.
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http://dx.doi.org/10.1128/JB.186.15.5017-5030.2004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC451596PMC
August 2004
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