Publications by authors named "Sapna Gupta"

46 Publications

Analysis of differential neonatal lethality in cystathionine β-synthase deficient mouse models using metabolic profiling.

FASEB J 2021 Jun;35(6):e21629

Cancer Biology Program, Fox Chase Cancer Center, Philadelphia, PA, USA.

Cystathionine beta-synthase (CBS) is a key enzyme of the trans-sulfuration pathway that converts homocysteine to cystathionine. Loss of CBS activity due to mutation results in CBS deficiency, an inborn error of metabolism characterized by extreme elevation of plasma total homocysteine (tHcy). C57BL6 mice containing either a homozygous null mutation in the cystathionine β-synthase (Cbs ) gene or an inactive human CBS protein (Tg-G307S Cbs ) are born in mendelian numbers, but the vast majority die between 18 and 21 days of age due to liver failure. However, adult Cbs null mice that express a hypomorphic allele of human CBS as a transgene (Tg-I278T Cbs ) show almost no neonatal lethality despite having serum tHcy levels similar to mice with no CBS activity. Here, we characterize liver and serum metabolites in neonatal Cbs , Tg-G307S Cbs , and Tg-I278T Cbs mice at 6, 10, and 17 days of age to understand this difference. In serum, we observe similar elevations in tHcy in both Tg-G307S Cbs and Tg-I278T Cbs compared to control animals, but methionine is much more severely elevated in Tg-G307S Cbs mice. Large scale metabolomic analysis of liver tissue confirms that both methionine and methionine-sulfoxide are significantly more elevated in Tg-G307S Cbs animals, along with significant differences in several other metabolites including hexoses, amino acids, other amines, lipids, and carboxylic acids. Our data are consistent with a model that the neonatal lethality observed in CBS-null mice is driven by excess methionine resulting in increased stress on a variety of related pathways including the urea cycle, TCA cycle, gluconeogenesis, and phosphatidylcholine biosynthesis.
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http://dx.doi.org/10.1096/fj.202100302RDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8218533PMC
June 2021

Netrin G1 Promotes Pancreatic Tumorigenesis through Cancer-Associated Fibroblast-Driven Nutritional Support and Immunosuppression.

Cancer Discov 2021 Feb 30;11(2):446-479. Epub 2020 Oct 30.

Cancer Biology Program, Institute for Cancer Research, Fox Chase Cancer Center, Philadelphia, Pennsylvania.

Pancreatic ductal adenocarcinoma (PDAC) has a poor 5-year survival rate and lacks effective therapeutics. Therefore, it is of paramount importance to identify new targets. Using multiplex data from patient tissue, three-dimensional coculturing assays, and orthotopic murine models, we identified Netrin G1 (NetG1) as a promoter of PDAC tumorigenesis. We found that NetG1 cancer-associated fibroblasts (CAF) support PDAC survival, through a NetG1-mediated effect on glutamate/glutamine metabolism. Also, NetG1 CAFs are intrinsically immunosuppressive and inhibit natural killer cell-mediated killing of tumor cells. These protumor functions are controlled by a signaling circuit downstream of NetG1, which is comprised of AKT/4E-BP1, p38/FRA1, vesicular glutamate transporter 1, and glutamine synthetase. Finally, blocking NetG1 with a neutralizing antibody stunts tumorigenesis, suggesting NetG1 as potential target in PDAC. SIGNIFICANCE: This study demonstrates the feasibility of targeting a fibroblastic protein, NetG1, which can limit PDAC tumorigenesis by reverting the protumorigenic properties of CAFs. Moreover, inhibition of metabolic proteins in CAFs altered their immunosuppressive capacity, linking metabolism with immunomodulatory function...
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http://dx.doi.org/10.1158/2159-8290.CD-20-0775DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7858242PMC
February 2021

Strangulated right-sided diaphragmatic hernia presenting and treated as lung empyema: beware of the differential diagnosis.

BMJ Case Rep 2020 Jul 8;13(7). Epub 2020 Jul 8.

Royal Gwent Hospital, Newport, UK.

A 78-year-old man with no surgical history or recent trauma presented to the emergency department with sudden onset right-sided chest pain and dyspnoea. He was admitted under the physicians for investigations and was subsequently diagnosed with empyema of the right thorax. After no improvement with intravenous antibiotics, a chest drain was inserted; no pus was drained. He worsened clinically; a repeated CT scan demonstrated an incarcerated loop of small bowel within the right thoracic cavity secondary to a diaphragmatic hernia (DH). The patient had emergency surgery to remove necrotic small bowel and to lavage the thorax. Strangulated DH should be considered as a differential diagnosis where presentation is unusual and empyema does not improve after initial management.
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http://dx.doi.org/10.1136/bcr-2019-233440DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7348464PMC
July 2020

Global Trigger Tool: Proficient Adverse Drug Reaction Autodetection Method in Critical Care Patient Units.

Indian J Crit Care Med 2020 Mar;24(3):172-178

Department of Orthopedics, Smt. NHL Municipal Medical College, Ahmedabad, Gujarat, India.

Background: Emergency department (ED) being the most crucial part of hospital, where adverse drug reactions (ADRs) often go undetected. Trigger tools are proficient ADR detection methods, which have only been applied for retrospective surveillance. We did a prospective analysis to further refine the trigger tool application in healthcare settings.

Objective: To estimate the prevalence of ADRs and prospectively evaluate the importance of using trigger tools for their detection.

Materials And Methods: A prospective study was conducted in the ED for the presence of triggers in patient records to monitor and report ADRs by applying the Institute for Healthcare Improvement (IHI) trigger tool methodology.

Results: Four hundred sixty-three medical records were analyzed randomly using 51 trigger tools, where triggers were found in 181 (39.09%) and ADRs in 62 (13.39%) patients. The prevalence of ADR was 13.39%. According to the World Health Organization (WHO)-Uppsala Monitoring Centre (UMC) causality scale, 47 (75.8%) were classified as probable and 15 (24.2%) as possible, wherein 39 (62.9%) were predictable and 8 (12.9%) were definitely preventable. Most common triggers were abrupt medication stoppage (34.98%), antiemetic use (25.91%), and time in ED >6 hours (17.49%). The positive predictive values (PPVs) of triggers such as international normalized ratio (INR) > 4 ( = 0.0384), vitamin K administration ( = 0.002), steroid use ( = 0.0001), abrupt medication stoppage ( = 0.0077), transfusion of blood or blood products ( = 0.004), and rash ( = 0.0042) showed statistically significant results, which make the event detection process more structured when these triggers are positive. Presence of five or more triggers has statistically significant chances of developing an ADR ( < 0.05).

Conclusion: Trigger tool could be a viable method to identify ADRs when compared to the traditional ADR identification methods, but there is insufficient data on IHI tool and its use to identify ADRs in the general outpatient setting. Healthcare providers may benefit from better trigger tools to help them detect ADRs.

How To Cite This Article: Pandya AD, Patel K, Rana D, Gupta SD, Malhotra SD, Patel P. Global Trigger Tool: Proficient Adverse Drug Reaction Autodetection Method in Critical Care Patient Units. Indian J Crit Care Med 2020;24(3):172-178.
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http://dx.doi.org/10.5005/jp-journals-10071-23367DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7225762PMC
March 2020

Analysis of the Qatari R336C cystathionine β-synthase protein in mice.

J Inherit Metab Dis 2019 09 10;42(5):831-838. Epub 2019 Jul 10.

Cancer Biology Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania.

Classical homocystinuria is a recessive inborn error of metabolism caused by mutations in the cystathionine beta-synthase (CBS) gene. The highest incidence of CBS deficiency in the world is found in the country of Qatar due to the combination of high rates of consanguinity and the presence of a founder mutation, c.1006C>T (p.R336C). This mutation does not respond to pyridoxine and is considered severe. Here we describe the creation of a mouse that is null for the mouse Cbs gene and expresses human p.R336C CBS from a zinc-inducible transgene (Tg-R336C Cbs ). Zinc-treated Tg-R336C Cbs mice have extreme elevation in both serum total homocysteine (tHcy) and liver tHcy compared with control transgenic mice. Both the steady-state protein levels and CBS enzyme activity levels in liver lysates from Tg-R336C Cbs mice are significantly reduced compared to that found in Tg-hCBS Cbs mice expressing wild-type human CBS. Treatment of Tg-R336C Cbs mice with the proteasome inhibitor bortezomib results in stabilization of liver CBS protein and an increase in activity to levels found in corresponding Tg-hCBS Cbs wild type mice. Surprisingly, serum tHcy did not fully correct even though liver enzyme activity was as high as control animals. This discrepancy is explained by in vitro enzymatic studies of mouse liver extracts showing that p.R336C causes reduced binding affinity for the substrate serine by almost 7-fold and significantly increased dependence on pyridoxal phosphate in the reaction buffer. These studies demonstrate that the p.R336C alteration effects both protein stability and substrate/cofactor binding.
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http://dx.doi.org/10.1002/jimd.12140DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7336392PMC
September 2019

In silico and in vivo models for Qatari-specific classical homocystinuria as basis for development of novel therapies.

Hum Mutat 2019 02 23;40(2):230-240. Epub 2018 Nov 23.

Department of Biomedical Sciences, College of Health Sciences, Qatar University, Doha, Qatar.

Homocystinuria is a rare inborn error of methionine metabolism caused by cystathionine β-synthase (CBS) deficiency. The prevalence of homocystinuria in Qatar is 1:1,800 births, mainly due to a founder Qatari missense mutation, c.1006C>T; p.R336C (p.Arg336Cys). We characterized the structure-function relationship of the p.R336C-mutant protein and investigated the effect of different chemical chaperones to restore p.R336C-CBS activity using three models: in silico, ΔCBS yeast, and CRISPR/Cas9 p.R336C knock-in HEK293T and HepG2 cell lines. Protein modeling suggested that the p.R336C induces severe conformational and structural changes, perhaps influencing CBS activity. Wild-type CBS, but not the p.R336C mutant, was able to restore the yeast growth in ΔCBS-deficient yeast in a complementation assay. The p.R336C knock-in HEK293T and HepG2 cells decreased the level of CBS expression and reduced its structural stability; however, treatment of the p.R336C knock-in HEK293T cells with betaine, a chemical chaperone, restored the stability and tetrameric conformation of CBS, but not its activity. Collectively, these results indicate that the p.R336C mutation has a deleterious effect on CBS structure, stability, and activity, and using the chemical chaperones approach for treatment could be ineffective in restoring p.R336C CBS activity.
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http://dx.doi.org/10.1002/humu.23682DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6586426PMC
February 2019

Mouse modeling and structural analysis of the p.G307S mutation in human cystathionine β-synthase () reveal effects on CBS activity but not stability.

J Biol Chem 2018 09 20;293(36):13921-13931. Epub 2018 Jul 20.

From the Cancer Biology Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111 and

Mutations in the cystathionine β-synthase () gene are the cause of classical homocystinuria, the most common inborn error in sulfur metabolism. The p.G307S mutation is the most frequent cause of CBS deficiency in Ireland, which has the highest prevalence of CBS deficiency in Europe. Individuals homozygous for this mutation tend to be severely affected and are pyridoxine nonresponsive, but the molecular basis for the strong effects of this mutation is unclear. Here, we characterized a transgenic mouse model lacking endogenous and expressing human p.G307S CBS protein from a zinc-inducible metallothionein promoter (). Unlike mice expressing other mutant alleles, the transgene could not efficiently rescue neonatal lethality of in a C57BL/6J background. In a C3H/HeJ background, zinc-induced mice expressed high levels of p.G307S CBS in the liver, and this protein variant forms multimers, similarly to mice expressing WT human CBS. However, the p.G307S enzyme had no detectable residual activity. Moreover, treating mice with proteasome inhibitors failed to significantly increase CBS-specific activity. These findings indicated that the G307S substitution likely affects catalytic function as opposed to causing a folding defect. Using molecular dynamics simulation techniques, we found that the G307S substitution likely impairs catalytic function by limiting the ability of the tyrosine at position 308 to assume the proper conformational state(s) required for the formation of the pyridoxal-cystathionine intermediate. These results indicate that the p.G307S CBS is stable but enzymatically inert and therefore unlikely to respond to chaperone-based therapy.
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http://dx.doi.org/10.1074/jbc.RA118.002164DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6130948PMC
September 2018

S-adenosylhomocysteine hydrolase over-expression does not alter S-adenosylmethionine or S-adenosylhomocysteine levels in CBS deficient mice.

Mol Genet Metab Rep 2018 Jun 12;15:15-21. Epub 2018 Jan 12.

Cancer Biology Program, Fox Chase Cancer Center, Philadelphia, PA, USA.

Elevated plasma total homocysteine (tHcy) is associated with a number of human diseases including coronary artery disease, stroke, osteoporosis and dementia. It is highly correlated with intracellular S-adenosylhomocysteine (SAH). Since SAH is a strong inhibitor of methyl-transfer reactions involving the methyl-donor S-adenosylmethionine (SAM), elevation in SAH could be an explanation for the wide association of tHcy and human disease. Here, we have created a transgenic mouse () that expresses human S-adenosylhomocysteine hydrolase () from a zinc-inducible promoter in the liver and kidney. Protein analysis shows that human AHCY is expressed well in both liver and kidney, but elevated AHCY enzyme activity (131% increase) is only detected in the kidney due to the high levels of endogenous mouse AHCY expression in liver. mice were crossed with mice lacking cystathionine β-synthase activity ( ) to explore the effect to AHCY overexpression in the context of elevated serum tHcy and elevated tissue SAM and SAH. Overexpression of AHCY had no significant effect on the phenotypes of mice or any effect on the steady state concentrations of methionine, total homocysteine, SAM, SAH, and SAM/SAH ratio in the liver and kidney. Furthermore, enhanced AHCY activity did not lower serum and tissue tHcy or methionine levels. Our data suggests that enhancing AHCY activity does not alter the distribution of methionine recycling metabolites, even when they are greatly elevated by mutations.
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http://dx.doi.org/10.1016/j.ymgmr.2018.01.002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6047060PMC
June 2018

The c.797 G>A (p.R266K) cystathionine β-synthase mutation causes homocystinuria by affecting protein stability.

Hum Mutat 2017 07 22;38(7):863-869. Epub 2017 May 22.

Cancer Biology Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania.

Mutations in the cystathionine beta-synthase (CBS) gene are the cause of classical homocystinuria, the most common inborn error in sulfur metabolism. The c.797 G>A (p.R266K) mutation in CBS was originally described in several Norwegian pyridoxine responsive CBS deficient patients, and heterologous gene expression studies have shown that the protein has near wild-type levels of enzyme activity. Here, we characterize a transgenic mouse lacking endogenous Cbs and expressing p.R266K human CBS protein from a zinc inducible metallothionein promoter (Tg-R266K Cbs ). Unlike mice expressing other mutant CBS alleles, the Tg-R266K transgene is unable to efficiently rescue neonatal lethality of Cbs on a C57BL/6J background. On a C3H/HeJ background, zinc-induced Tg-R266K Cbs mice express CBS mRNA, but have very low levels of CBS protein and enzyme activity, resulting in extreme elevations in serum total homocysteine (tHcy). Treatment with pyridoxine did not have any appreciable effect on tHcy, indicating this allele is not pyridoxine responsive in mice. However, treatment with the proteasome inhibitor bortezomib resulted in an 97% reduction in tHcy and a 2381% increase in liver CBS activity. These studies show that the p.R266K mutation causes increased proteasomal degradation in vivo, and that treatments that stabilize the protein can be used to reverse its effect.
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http://dx.doi.org/10.1002/humu.23240DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5525156PMC
July 2017

The c.797 G>A (p.R266K) cystathionine β-synthase mutation causes homocystinuria by affecting protein stability.

Hum Mutat 2017 07 22;38(7):863-869. Epub 2017 May 22.

Cancer Biology Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania.

Mutations in the cystathionine beta-synthase (CBS) gene are the cause of classical homocystinuria, the most common inborn error in sulfur metabolism. The c.797 G>A (p.R266K) mutation in CBS was originally described in several Norwegian pyridoxine responsive CBS deficient patients, and heterologous gene expression studies have shown that the protein has near wild-type levels of enzyme activity. Here, we characterize a transgenic mouse lacking endogenous Cbs and expressing p.R266K human CBS protein from a zinc inducible metallothionein promoter (Tg-R266K Cbs ). Unlike mice expressing other mutant CBS alleles, the Tg-R266K transgene is unable to efficiently rescue neonatal lethality of Cbs on a C57BL/6J background. On a C3H/HeJ background, zinc-induced Tg-R266K Cbs mice express CBS mRNA, but have very low levels of CBS protein and enzyme activity, resulting in extreme elevations in serum total homocysteine (tHcy). Treatment with pyridoxine did not have any appreciable effect on tHcy, indicating this allele is not pyridoxine responsive in mice. However, treatment with the proteasome inhibitor bortezomib resulted in an 97% reduction in tHcy and a 2381% increase in liver CBS activity. These studies show that the p.R266K mutation causes increased proteasomal degradation in vivo, and that treatments that stabilize the protein can be used to reverse its effect.
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http://dx.doi.org/10.1002/humu.23240DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5525156PMC
July 2017

Homocysteine modulates 5-lipoxygenase expression level via DNA methylation.

Aging Cell 2017 04 29;16(2):273-280. Epub 2016 Nov 29.

Department of Pharmacology and Center for Translational Medicine, Lewis Katz School of Medicine, Philadelphia, PA, 19140, USA.

Elevated levels of homocysteinemia (Hcy), a risk factor for late-onset Alzheimer's disease (AD), have been associated with changes in cell methylation. Alzheimer's disease is characterized by an upregulation of the 5-lipoxygenase (5LO), whose promoter is regulated by methylation. However, whether Hcy activates 5LO enzymatic pathway by influencing the methylation status of its promoter remains unknown. Brains from mice with high Hcy were assessed for the 5LO pathway and neuronal cells exposed to Hcy implemented to study the mechanism(s) regulating 5LO expression levels and the effect on amyloid β formation. Diet- and genetically induced high Hcy resulted in 5LO protein and mRNA upregulation, which was associated with a significant increase of the S-adenosylhomocysteine (SAH)/S-adenosylmethionine ratio, and reduced DNA methyltrasferases and hypomethylation of 5-lipoxygenase DNA. In vitro studies confirmed these results and demonstrated that the mechanism involved in the Hcy-dependent 5LO activation and amyloid β formation is DNA hypomethylation secondary to the elevated levels of SAH. Taken together these findings represent the first demonstration that Hcy directly influences 5LO expression levels and establish a previously unknown cross talk between these two pathways, which is highly relevant for AD pathogenesis. The discovery of such a novel link not only provides new mechanistic insights in the neurobiology of Hcy, but most importantly new therapeutic opportunities for the individuals bearing this risk factor for the disease.
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http://dx.doi.org/10.1111/acel.12550DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5334532PMC
April 2017

Lack of global epigenetic methylation defects in CBS deficient mice.

J Inherit Metab Dis 2017 01 21;40(1):113-120. Epub 2016 Jul 21.

Cancer Biology Program, Fox Chase Cancer Center, 333 Cottman Avenue, Philadelphia, PA, 19111, USA.

Cystathionine β-synthase (CBS) deficiency is a recessive inborn error of metabolism in which patients have extremely elevated plasma total homocysteine and have clinical manifestations in the vascular, visual, skeletal, and nervous systems. Homocysteine is an intermediary metabolite produced from the hydrolysis of S-adenosylhomocysteine (SAH), which is a by-product of methylation reactions involving the methyl-donor S-adenosylmethionine (SAM). Here, we have measured SAM, SAH, DNA and histone methylation status in an inducible mouse model of CBS deficiency to test the hypothesis that homocysteine-related phenotypes are caused by inhibition of methylation due to elevated SAH and reduced SAM/SAH ratio. We found that mice lacking CBS have elevated cellular SAH and reduced SAM/SAH ratios in both liver and kidney, but this was not associated with alterations in the level of 5-methylcytosine or various histone modifications. Using methylated DNA immunoprecipitation in combination with microarray, we found that of the 241 most differentially methylated promoter probes, 89 % were actually hypermethylated in CBS deficient mice. In addition, we did not find that changes in DNA methylation correlated well with changes in RNA expression in the livers of induced and uninduced CBS mice. Our data indicates that reduction in the SAM/SAH ratio, due to loss of CBS activity, does not result in overall hypomethylation of either DNA or histones.
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http://dx.doi.org/10.1007/s10545-016-9958-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5300059PMC
January 2017

The effect of dietary modulation of sulfur amino acids on cystathionine β synthase-deficient mice.

Ann N Y Acad Sci 2016 Jan 24;1363:80-90. Epub 2015 Nov 24.

Cancer Biology Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania.

Cystathionine β synthase (CBS) is a key enzyme in the methionine and cysteine metabolic pathway, acting as a metabolic gatekeeper to regulate the flow of fixed sulfur from methionine to cysteine. Mutations in the CBS gene cause clinical CBS deficiency, a disease characterized by elevated plasma total homocysteine (tHcy) and methionine and decreased plasma cysteine. The treatment goal for CBS-deficient patients is to normalize the metabolic values of these three metabolites using a combination of vitamin therapy and dietary manipulation. To better understand the effectiveness of nutritional treatment strategies, we have performed a series of long-term dietary manipulation studies using our previously developed Tg-I278T Cbs(-/-) mouse model of CBS deficiency and sibling Tg-I278T Cbs(+/-) controls. Tg-I278T Cbs(-/-) mice have undetectable levels of CBS activity, extremely elevated plasma tHcy, modestly elevated plasma methionine, and low plasma cysteine. They exhibit several easily assayable phenotypes, including osteoporosis, loss of fat mass, reduced life span, and facial alopecia. The diets used in these studies differed in the amounts of sulfur amino acids or sulfur amino acid precursors. In this review, we will discuss our findings and their relevance to CBS deficiency and the concept of gene-diet interaction.
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http://dx.doi.org/10.1111/nyas.12967DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4801721PMC
January 2016

Betaine supplementation is less effective than methionine restriction in correcting phenotypes of CBS deficient mice.

J Inherit Metab Dis 2016 Jan 1;39(1):39-46. Epub 2015 Aug 1.

Cancer Biology Program, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA.

Cystathionine beta synthase (CBS) deficiency is a recessive inborn error of metabolism characterized by elevated serum total homocysteine (tHcy). Betaine supplementation, which can lower tHcy by stimulating homocysteine remethylation to methionine, is often given to CBS deficient patients in combination with other treatments such as methionine restriction and supplemental B-vitamins. However, the effectiveness of betaine supplementation by itself in the treatment of CBS deficiency has not been well explored. Here, we have examined the effect of a betaine supplemented diet on the Tg-I278T Cbs (-/-) mouse model of CBS deficiency and compared its effectiveness to our previously published data using a methionine restricted diet. Tg-I278T Cbs (-/-) mice on betaine, from the time of weaning until for 240 days of age, had a 40 % decrease in mean tHcy level and a 137 % increase in serum methionine levels. Betaine-treated Tg-I278T Cbs (-/-) mice also exhibited increased levels of betaine-dependent homocysteine methyl transferase (BHMT), increased levels of the lipogenic enzyme stearoyl-coenzyme A desaturase (SCD-1), and increased lipid droplet accumulation in the liver. Betaine supplementation largely reversed the hair loss phenotype in Tg-I278T Cbs (-/-) animals, but was far less effective than methionine restriction in reversing the weight-loss, fat-loss, and osteoporosis phenotypes. Surprisingly, betaine supplementation had several negative effects in control Tg-I278T Cbs (+/-) mice including decreased weight gain, lean mass, and bone mineral density. Our findings indicate that while betaine supplementation does have some beneficial effects, it is not as effective as methionine restriction for reversing the phenotypes associated with severe CBS deficiency in mice.
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http://dx.doi.org/10.1007/s10545-015-9883-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4784539PMC
January 2016

High homocysteine induces betaine depletion.

Biosci Rep 2015 Apr 28;35(4). Epub 2015 Apr 28.

‡Laboratory for Clinical Biochemistry and Metabolism, Department of General Pediatrics, Center for Pediatrics and Adolescent Medicine University Hospital, Freiburg D-79106, Germany.

Betaine is the substrate of the liver- and kidney-specific betaine-homocysteine (Hcy) methyltransferase (BHMT), an alternate pathway for Hcy remethylation. We hypothesized that BHMT is a major pathway for homocysteine removal in cases of hyperhomocysteinaemia (HHcy). Therefore, we measured betaine in plasma and tissues from patients and animal models of HHcy of genetic and acquired cause. Plasma was collected from patients presenting HHcy without any Hcy interfering treatment. Plasma and tissues were collected from rat models of HHcy induced by diet and from a mouse model of cystathionine β-synthase (CBS) deficiency. S-adenosyl-methionine (AdoMet), S-adenosyl-homocysteine (AdoHcy), methionine, betaine and dimethylglycine (DMG) were quantified by ESI-LC-MS/MS. mRNA expression was quantified using quantitative real-time (QRT)-PCR. For all patients with diverse causes of HHcy, plasma betaine concentrations were below the normal values of our laboratory. In the diet-induced HHcy rat model, betaine was decreased in all tissues analysed (liver, brain, heart). In the mouse CBS deficiency model, betaine was decreased in plasma, liver, heart and brain, but was conserved in kidney. Surprisingly, BHMT expression and activity was decreased in liver. However, in kidney, BHMT and SLC6A12 expression was increased in CBS-deficient mice. Chronic HHcy, irrespective of its cause, induces betaine depletion in plasma and tissues (liver, brain and heart), indicating a global decrease in the body betaine pool. In kidney, betaine concentrations were not affected, possibly due to overexpression of the betaine transporter SLC6A12 where betaine may be conserved because of its crucial role as an osmolyte.
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http://dx.doi.org/10.1042/BSR20150094DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4613678PMC
April 2015

Propensity Score Adjusted Comparison of MIDCAB Versus Full Sternotomy Left Anterior Descending Artery Revascularization.

Innovations (Phila) 2015 May-Jun;10(3):174-8

From the Department of Cardiac Surgery, Harefield Hospital, London, United Kingdom.

Objective: Minimally invasive direct coronary artery bypass (MIDCAB) has been proposed as an attractive alternative to full sternotomy (FS) revascularization in isolated left anterior descending (LAD) artery disease not suitable for percutaneous coronary intervention. However, surgeons are still reluctant to perform MIDCAB owing to concerns about early and late outcomes. We aimed to compare short- and long-term outcomes after MIDCAB versus FS revascularization.

Methods: Prospectively collected data from institutional database were reviewed. Data for late mortality were obtained from the General Register Office. MIDCAB was performed in 318 patients, whereas 159 had FS, according to the surgeon's preference, among 477 patients with isolated LAD disease. Inverse propensity score weighting was used to estimate treatment effects on short- and long-term outcomes.

Results: In the propensity score-adjusted analysis, FS revascularization versus MIDCAB was associated increased rate of surgical site infection [4 (2.8%) versus 1 (0.7%); P = 0.04]. The 2 groups did not significantly differ with regard to other complications including operative mortality. Mean length of hospital stay was similar for the 2 groups. After a mean follow-up time of 6.2 years (interquartile range, 3.5-9.7 years), compared to MIDCAB, FS was not associated with an improved late survival (β coef, -1.42; standard error, 1.65; P = 0.39) or risk reduction for repeat revascularization (β coef, 1.22; standard error, 1.41; P = 0.15).

Conclusions: MIDCAB was associated with a trend toward better short-term outcomes and excellent long-term results comparable to FS revascularization. According to these findings, surgeons should not be reluctant to perform MIDCAB in isolated LAD disease.
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http://dx.doi.org/10.1097/IMI.0000000000000162DOI Listing
May 2016

Protein arginine hypomethylation in a mouse model of cystathionine β-synthase deficiency.

FASEB J 2014 Jun 14;28(6):2686-95. Epub 2014 Feb 14.

Institute for Medicines and Pharmaceutical Sciences (iMed.UL) and Department of Biochemistry and Human Biology, Faculty of Pharmacy, University of Lisbon, Lisbon, Portugal;

Accumulation of the homocysteine (Hcy) precursor S-adenosylhomocysteine (AdoHcy) may cause cellular hypomethylation in the setting of hyperhomocysteinemia because of cystathionine β-synthase (CBS) deficiency, an inborn error of metabolism. To test this hypothesis, DNA and protein arginine methylation status were assessed in liver, brain, heart, and kidney obtained from a previously described mouse model of CBS deficiency. Metabolite levels in tissues and serum were determined by high-performance liquid chromatography or liquid chromatography-electrospray ionization-tandem mass spectrometry. Global DNA and protein arginine methylation status were evaluated as the contents of 5-methyldeoxycytidine in DNA and of methylarginines in proteins, respectively. In addition, histone arginine methylation was assessed by Western blotting. CBS-deficient mice exhibited increased (>6-fold) Hcy and AdoHcy levels in all tissues examined compared with control levels. In addition, global DNA methylation status was not affected, but global protein arginine methylation status was decreased (10-35%) in liver and brain. Moreover, asymmetric dimethylation of arginine 3 on histone H4 (H4R3me2a) content was markedly decreased in liver, and no differences were observed for the other histone arginine methylation marks examined. Our results show that CBS-deficient mice present severe accumulation of tissue Hcy and AdoHcy, protein arginine hypomethylation in liver and brain, and decreased H4R3me2a content in liver. Therefore, protein arginine hypomethylation arises as a potential player in the pathophysiology of CBS deficiency.
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http://dx.doi.org/10.1096/fj.13-246579DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4021445PMC
June 2014

Cystathionine β-synthase-deficient mice thrive on a low-methionine diet.

FASEB J 2014 Feb 4;28(2):781-90. Epub 2013 Nov 4.

1Fox Chase Cancer Center, 333 Cottman Ave., Philadelphia, PA 19111, USA.

Cystathionine β-synthase (CBS) deficiency is a recessive inborn error of metabolism characterized by elevated serum total homocysteine (tHcy). Previously, our laboratory developed a mouse model of CBS deficiency, TgI278T Cbs(-)/(-) (abbreviated as Cbs(-/-)), characterized by low weight, low adiposity, decreased Scd-1 expression, facial alopecia, and osteoporosis. To determine the potential benefit of a methionine-restricted diet (MRD), we fed Cbs(-/-) and Cbs(+/-) control mice either an MRD or a regular diet (RD) from weaning till 240 d of age. Cbs(-/-) mice fed the MRD had a 77% decrease in tHcy, 28% increase in weight, 130% increase in fat mass, 82% increase in Scd-1 expression, and 10.6% increase in bone density and entirely lacked the alopecia phenotype observed in age-matched Cbs(-/-) mice fed the RD. At the end of the study, Cbs(-/-) mice fed the MRD were phenotypically indistinguishable from Cbs(+/-) mice fed the RD. Notably, whereas the MRD diet was highly beneficial to Cbs(-/-) mice, it had nearly opposite effect on Cbs(+/-) mice. These studies show that a low-methionine diet can correct the phenotypic consequences of loss of CBS and provide a striking example of how genotype and diet can interact to influence phenotype in mammals.
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http://dx.doi.org/10.1096/fj.13-240770DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3898656PMC
February 2014

Correction of cystathionine β-synthase deficiency in mice by treatment with proteasome inhibitors.

Hum Mutat 2013 Aug 13;34(8):1085-93. Epub 2013 May 13.

Cancer Biology Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111, USA.

Cystathionine beta-synthase (CBS) deficiency is an inborn error of metabolism characterized by extremely elevated levels of plasma total homocysteine. The vast majority of CBS-deficient patients have missense mutations located in the CBS gene that result in the production of either misfolded or unstable protein. Here, we examine the effect of proteasome inhibitors on mutant CBS function using two different mouse models of CBS deficiency. These mice lack mouse CBS and express a missense mutant human CBS enzyme (either p.I278T or p.S466L) that has less than 5% of normal liver CBS activity, resulting in a 10-30-fold elevation in plasma homocysteine levels. We show that treatment of these mice with two different proteasome inhibitors can induce liver Hsp70, Hsp40, and Hsp27, increase levels of active CBS, and lower plasma homocysteine levels to within the normal range. However, response rates varied, with 100% (8/8) of the p.S466L animals showing correction, but only 38% (10/26) of the p.I278T animals. In total, our data show that treatment with proteostasis modulators can restore significant enzymatic activity to mutant misfolded CBS enzymes and suggests that they may be useful in treating certain types of genetic diseases caused by missense mutations.
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http://dx.doi.org/10.1002/humu.22335DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3941476PMC
August 2013

The TSC1/2 complex controls Drosophila pigmentation through TORC1-dependent regulation of catecholamine biosynthesis.

PLoS One 2012 7;7(11):e48720. Epub 2012 Nov 7.

Fox Chase Cancer Center, Philadelphia, Pennsylvania, United States of America.

In Drosophila, the pattern of adult pigmentation is initiated during late pupal stages by the production of catecholamines DOPA and dopamine, which are converted to melanin. The pattern and degree of melanin deposition is controlled by the expression of genes such as ebony and yellow as well as by the enzymes involved in catecholamine biosynthesis. In this study, we show that the conserved TSC/TORC1 cell growth pathway controls catecholamine biosynthesis in Drosophila during pigmentation. We find that high levels of Rheb, an activator of the TORC1 complex, promote premature pigmentation in the mechanosensory bristles during pupal stages, and alter pigmentation in the cuticle of the adult fly. Disrupting either melanin synthesis by RNAi knockdown of melanogenic enzymes such as tyrosine hydroxylase (TH), or downregulating TORC1 activity by Raptor knockdown, suppresses the Rheb-dependent pigmentation phenotype in vivo. Increased Rheb activity drives pigmentation by increasing levels of TH in epidermal cells. Our findings indicate that control of pigmentation is linked to the cellular nutrient-sensing pathway by regulating levels of a critical enzyme in melanogenesis, providing further evidence that inappropriate activation of TORC1, a hallmark of the human tuberous sclerosis complex tumor syndrome disorder, can alter metabolic and differentiation pathways in unexpected ways.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0048720PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3492411PMC
May 2013

Brain phenotype of transgenic mice overexpressing cystathionine β-synthase.

PLoS One 2012 12;7(1):e29056. Epub 2012 Jan 12.

Unité de Biologie Fonctionnelle et Adaptative, CNRS EAC 4413, Université Paris Diderot, Sorbonne Paris Cité, Paris, France.

Background: The cystathionine β-synthase (CBS) gene, located on human chromosome 21q22.3, is a good candidate for playing a role in the Down Syndrome (DS) cognitive profile: it is overexpressed in the brain of individuals with DS, and it encodes a key enzyme of sulfur-containing amino acid (SAA) metabolism, a pathway important for several brain physiological processes.

Methodology/principal Findings: Here, we have studied the neural consequences of CBS overexpression in a transgenic mouse line (60.4P102D1) expressing the human CBS gene under the control of its endogenous regulatory regions. These mice displayed a ∼2-fold increase in total CBS proteins in different brain areas and a ∼1.3-fold increase in CBS activity in the cerebellum and the hippocampus. No major disturbance of SAA metabolism was observed, and the transgenic mice showed normal behavior in the rotarod and passive avoidance tests. However, we found that hippocampal synaptic plasticity is facilitated in the 60.4P102D1 line.

Conclusion/significance: We demonstrate that CBS overexpression has functional consequences on hippocampal neuronal networks. These results shed new light on the function of the CBS gene, and raise the interesting possibility that CBS overexpression might have an advantageous effect on some cognitive functions in DS.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0029056PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3257219PMC
May 2012

Cystathionine beta-synthase deficiency causes fat loss in mice.

PLoS One 2011 11;6(11):e27598. Epub 2011 Nov 11.

Cancer Biology Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania, United States of America.

Cystathionine beta synthase (CBS) is the rate-limiting enzyme responsible for the de novo synthesis of cysteine. Patients with CBS deficiency have greatly elevated plasma total homocysteine (tHcy), decreased levels of plasma total cysteine (tCys), and often a marfanoid appearance characterized by thinness and low body-mass index (BMI). Here, we characterize the growth and body mass characteristics of CBS deficient TgI278T Cbs(-/-) mice and show that these animals have significantly decreased fat mass and tCys compared to heterozygous sibling mice. The decrease in fat mass is accompanied by a 34% decrease in liver glutathione (GSH) along with a significant decrease in liver mRNA and protein for the critical fat biosynthesizing enzyme Stearoyl CoA desaturase-1 (Scd-1). Because plasma tCys has been positively associated with fat mass in humans, we tested the hypothesis that decreased tCys in TgI278T Cbs(-/-) mice was the cause of the lean phenotype by placing the animals on water supplemented with N-acetyl cysteine (NAC) from birth to 240 days of age. Although NAC treatment in TgI278T Cbs(-/-) mice caused significant increase in serum tCys and liver GSH, there was no increase in body fat content or in liver Scd-1 levels. Our results show that lack of CBS activity causes loss of fat mass, and that this effect appears to be independent of low serum tCys.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0027598PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3214081PMC
April 2012

Huge vulval elephantiasis: Anesthetic management for caesarean delivery.

J Anaesthesiol Clin Pharmacol 2011 Jul;27(3):416-7

Department of Anaesthesiology and Critical Care, R.N.T. Medical College, Udaipur, India.

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http://dx.doi.org/10.4103/0970-9185.83702DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3161482PMC
July 2011

Serum amino acid levels as a biomarker for renal cell carcinoma.

J Urol 2011 Oct 17;186(4):1206-12. Epub 2011 Aug 17.

Cancer Biology Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111, USA.

Purpose: Prognosis in renal cell carcinoma is dependent on tumor stage at presentation, with significant differences in survival between early and late stage disease. Currently to our knowledge no screening tests or biomarkers have been identified for the early detection of kidney cancer. Therefore, we investigated whether serum amino acid profiles are a potentially useful biomarker in patients with renal cell carcinoma.

Materials And Methods: The concentrations of 26 amino acids were determined in serum taken preoperatively from 189 patients with renal cell carcinoma, and from 104 age and sex matched controls.

Results: Statistically significant changes were observed in patient levels of 15 amino acids, with 13 being decreased and 2 being increased. A logistic regression model using 8 amino acids including cysteine, ornithine, histidine, leucine, tyrosine, proline, valine and lysine was created to distinguish cases from controls. A receiver operator curve based on this model had an area under the curve of 0.81. This same model also had predictive value in terms of overall survival and tumor recurrence in patients with renal cell carcinoma.

Conclusions: Our findings suggest that serum amino acid levels may be useful as a screening tool for the identification of individuals with renal cell carcinoma and the prediction of outcomes.
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http://dx.doi.org/10.1016/j.juro.2011.05.085DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3180900PMC
October 2011

Inhibition of betaine-homocysteine S-methyltransferase in rats causes hyperhomocysteinemia and reduces liver cystathionine β-synthase activity and methylation capacity.

Nutr Res 2011 Jul;31(7):563-71

Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.

Methylation of homocysteine (Hcy) by betaine-Hcy S-methyltransferase (BHMT) produces methionine, which is required for S-adenosylmethionine (SAM) synthesis. We have recently shown that short-term dietary intake of S-(Δ-carboxybutyl)-dl-Hcy (D,L-CBHcy), a potent and specific inhibitor of BHMT, significantly decreases liver BHMT activity and SAM concentrations but does not have an adverse affect on liver histopathology, plasma markers of liver damage, or DNA methylation in rats. The present study was designed to investigate the hypothesis that BHMT is required to maintain normal liver and plasma amino acid and glutathione profiles, and liver SAM and lipid accumulation. Rats were fed an adequate (4.5 g/kg methionine and 3.7 g/kg cystine), cysteine-devoid (4.5 g/kg methionine and 0 g/kg cystine), or methionine-deficient (1.5 g/kg methionine and 3.7 g/kg cystine) diet either with or without L-CBHcy for 3 or 14 days. All rats fed L-CBHcy had increased total plasma Hcy (2- to 5-fold) and reduced liver BHMT activity (>90%) and SAM concentrations (>40%). S-(Δ-carboxybutyl)-l-Hcy treatment slightly reduced liver glutathione levels in rats fed the adequate or cysteine-devoid diet for 14 days. Rats fed the methionine-deficient diet with L-CBHcy developed fatty liver. Liver cystathionine β-synthase activity was reduced in all L-CBHcy-treated animals, and the effect was exacerbated as time on the L-CBHcy diet increased. Our data indicate that BHMT activity is required to maintain adequate levels of liver SAM and low levels of total plasma Hcy and might be critical for liver glutathione and triglyceride homeostasis under some dietary conditions.
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http://dx.doi.org/10.1016/j.nutres.2011.06.004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3156413PMC
July 2011

Hyperhomocysteinemia impairs endothelium-derived hyperpolarizing factor-mediated vasorelaxation in transgenic cystathionine beta synthase-deficient mice.

Blood 2011 Aug 8;118(7):1998-2006. Epub 2011 Jun 8.

Department of Pharmacology, Temple University School of Medicine, Philadelphia, PA 19140, USA.

Hyperhomocysteinemia (HHcy) is associated with endothelial dysfunction (ED), but the mechanism is largely unknown. In this study, we investigated the role and mechanism of HHcy-induced ED in microvasculature in our newly established mouse model of severe HHcy (plasma total homocysteine, 169.5 μM). We found that severe HHcy impaired nitric oxide (NO)- and endothelium-derived hyperpolarizing factor (EDHF)-mediated, endothelium-dependent relaxations of small mesenteric arteries (SMAs). Endothelium-independent and prostacyclin-mediated endothelium-dependent relaxations were not changed. A nonselective Ca(2+)-activated potassium channel (K(Ca)) inhibitor completely blocked EDHF-mediated relaxation. Selective blockers for small-conductance K(Ca) (SK) or intermediate-conductance K(Ca) (IK) failed to inhibit EDHF-mediated relaxation in HHcy mice. HHcy increased the levels of SK3 and IK1 protein, superoxide (O(2)(-)), and 3-nitrotyrosine in the endothelium of SMAs. Preincubation with antioxidants and peroxynitrite (ONOO(-)) inhibitors improved endothelium-dependent and EDHF-mediated relaxations and decreased O(2)(-) production in SMAs from HHcy mice. Further, EDHF-mediated relaxation was inhibited by ONOO(-) and prevented by catalase in the control mice. Finally, L-homocysteine stimulated O(2)(-) production, which was reversed by antioxidants, and increased SK/IK protein levels and tyrosine nitration in cultured human cardiac microvascular endothelial cells. Our results suggest that HHcy impairs EDHF relaxation in SMAs by inhibiting SK/IK activities via oxidation- and tyrosine nitration-related mechanisms.
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http://dx.doi.org/10.1182/blood-2011-01-333310DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3158725PMC
August 2011

Hyperthermia with radiation in the treatment of locally advanced head and neck cancer: a report of randomized trial.

J Cancer Res Ther 2010 Oct-Dec;6(4):492-6

Department of Radiation Oncology, Dr. Balabhai Nanavati Hospital, Mumbai, India.

Background: Head and neck cancer is the leading cause of male mortality due to cancer in India. Surgery, radiation alone or in combination has been the backbone of treatment strategies. Chemo-radiation has emerged as the standard of care in most types of head and neck cancer. This strategy has the advantage of maintaining both structure and functions, albeit with increased acute and delayed side effects. Radiation with hyperthermia can achieve the same objective without additional toxicities.

Materials And Methods: A total of 56 patients were randomized to radiation therapy (RT) alone or RT-hyperthermia (RT-HT) arm. Twenty-six patients were included in RT alone arm and 28 patients in the RT-HT arm. Both groups were evenly matched for age, sex, and stage. Patients in both the arms received radiation to a dose of 66-70 Gy in 6.5-7 weeks. Patients in the study group received weekly HT. HT was started after impedance matching to last for 30 minutes.

Results: Complete response was seen in 42.4% of RT alone group compare to 78.6% in the HT group. The difference was statistically significant ( < 0.05). Kaplan-Meir analysis of survival also showed a significant improvement in favor of RT-HT. No dose limiting thermal burns and excessive mucosal or thermal toxicity were recorded.

Conclusion: Radiofrequency (RF) based heating and radical radiation of head and neck cancers is better than in RT alone group. HT should be considered as a valid option wherever the facility for HT is available. This report should infuse greater confidence in radiation Oncologists to practice HT as an adjuvant treatment modality.
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http://dx.doi.org/10.4103/0973-1482.77101DOI Listing
June 2011

Susceptibility to intestinal tumorigenesis in folate-deficient mice may be influenced by variation in one-carbon metabolism and DNA repair.

J Nutr Biochem 2011 Nov 28;22(11):1022-9. Epub 2010 Dec 28.

Department of Human Genetics, McGill University-Montreal Children's Hospital, Montreal, Quebec, Canada.

Low dietary folate is associated with increased risk of colorectal cancer. In earlier work, we showed that folate deficiency induced intestinal tumors in BALB/c but not C57Bl/6 mice through increased dUTP incorporation into DNA with consequent DNA damage. To determine whether strain differences between one-carbon metabolism and DNA repair pathways could contribute to increased tumorigenesis in BALB/c mice, we measured amino acids and folate in the normal intestinal tissue of both strains fed a control diet or a folate-deficient diet. We also determined the expression of critical folate-metabolizing enzymes and several DNA repair enzymes. BALB/c mice had lower intestinal serine (major cellular one-carbon donor), methionine and total folate than C57Bl/6 mice under both dietary conditions. BALB/c mice had higher messenger RNA and protein levels of three folate-interconverting enzymes: trifunctional methyleneTHF (5,10-methylenetetrahydrofolate) dehydrogenase-methenylTHF cyclohydrolase-formylTHF (10-formyltetrahydrofolate) synthetase 1, bifunctional methyleneTHF dehydrogenase-methenylTHF cyclohydrolase and methylenetetrahydrofolate reductase. This pattern of expression could limit the availability of methyleneTHF for conversion of dUMP to dTMP. BALB/c mice also had higher levels of uracil DNA glycosylase 2 protein without an increase in the rate-limiting DNA polymerase β enzyme, compared with C57Bl/6 mice. We conclude that BALB/c mice may be more prone to DNA damage through decreased amounts of one-carbon donors and the diversion of methyleneTHF away from the conversion of dUMP to dTMP. In addition, incomplete excision repair of uracil in DNA could lead to accumulation of toxic repair intermediates and promotion of tumorigenesis in this tumor-susceptible strain.
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http://dx.doi.org/10.1016/j.jnutbio.2010.07.015DOI Listing
November 2011

Dietary intake of S-(alpha-carboxybutyl)-DL-homocysteine induces hyperhomocysteinemia in rats.

Nutr Res 2010 Jul;30(7):492-500

Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.

Betaine homocysteine S-methyltransferase (BHMT) catalyzes the transfer of a methyl group from betaine to homocysteine (Hcy), forming dimethylglycine and methionine. We previously showed that inhibiting BHMT in mice by intraperitoneal injection of S-(alpha-carboxybutyl)-DL-homocysteine (CBHcy) results in hyperhomocysteinemia. In the present study, CBHcy was fed to rats to determine whether it could be absorbed and cause hyperhomocysteinemia as observed in the intraperitoneal administration of the compound in mice. We hypothesized that dietary administered CBHcy will be absorbed and will result in the inhibition of BHMT and cause hyperhomocysteinemia. Rats were meal-fed every 8 hours an L-amino acid-defined diet either containing or devoid of CBHcy (5 mg per meal) for 3 days. The treatment decreased liver BHMT activity by 90% and had no effect on methionine synthase, methylenetetrahydrofolate reductase, phosphatidylethanolamine N-methyltransferase, and CTP:phosphocholine cytidylyltransferase activities. In contrast, cystathionine beta-synthase activity and immunodetectable protein decreased (56% and 26%, respectively) and glycine N-methyltransferase activity increased (52%) in CBHcy-treated rats. Liver S-adenosylmethionine levels decreased by 25% in CBHcy-treated rats, and S-adenosylhomocysteine levels did not change. Furthermore, plasma choline decreased (22%) and plasma betaine increased (15-fold) in CBHcy-treated rats. The treatment had no effect on global DNA and CpG island methylation, liver histology, and plasma markers of liver damage. We conclude that CBHcy-mediated BHMT inhibition causes an elevation in total plasma Hcy that is not normalized by the folate-dependent conversion of Hcy to methionine. Furthermore, metabolic changes caused by BHMT inhibition affect cystathionine beta-synthase and glycine N-methyltransferase activities, which further deteriorate plasma Hcy levels.
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http://dx.doi.org/10.1016/j.nutres.2010.06.017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2929918PMC
July 2010

Chemoradiation with hyperthermia in the treatment of head and neck cancer.

Int J Hyperthermia 2010 Feb;26(1):21-5

Advanced Centre for Radiation Oncology, Dr Balabhai Nanavati Hospital, Mumbai 400056, India.

Purpose: The management of head and neck cancer requires skilled integration of multiple modalities such as surgery, radiation, chemotherapy and hyperthermia. Chemoradiation can benefit from the addition of a proven modality such as hyperthermia in increasing survival, disease-free survival and quality of life without increasing the risk of complication. The purpose of this retrospective study was to evaluate the feasibility and efficacy of hyperthermia with chemoradiation in advanced head and neck cancers.

Materials And Methods: Between January 2004 and May 2008 40 patients with advanced head and neck cancers were allocated for hyperthermia with chemoradiotherapy. All patients underwent radiation on a telecobalt machine. A total dose of 70 Gy in 7 weeks with conventional fractionation was given with weekly chemotherapy of cisplatin 50 mg or paclitaxel 60 mg. Patients underwent hyperthermia on a radiofrequency machine at 8.2 MHz for 30 min at 41 degrees -43 degrees C with 10 min pre-cooling to 5 degrees C.

Results: No patient had life-threatening complications. Only 38 out of 40 patients were eligible for assessment of immediate response as one patient died during treatment and the other did not complete treatment. Complete response was 76.23% (29 pts), and 23.68% (9 pts) had partial response. Overall survival by the Kaplan-Meir method was 75.69% at 1 year and 63.08% at 2 years. No enhanced mucosal or thermal toxicities were documented as compared to our earlier experience with chemoradiation.

Conclusion: This retrospective analysis demonstrates the feasibility and efficacy of chemoradiation with hyperthermia in advanced head and neck cancer. The study is encouraging enough to start a randomised trial to compare chemoradiation with triple modality of treatment.
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http://dx.doi.org/10.3109/02656730903418283DOI Listing
February 2010