Sulfur amino acid metabolism and related metabotypes of autism spectrum disorder: A review of biochemical evidence for a hypothesis.

There are multiple lines of evidence for an impaired sulfur amino acid (SAA) metabolism in autism spectrum disorder (ASD). For instance, the concentrations of methionine, cysteine and S-adenosylmethionine (SAM) in body fluids of individuals with ASD is significantly lower while the concentration of S-adenosylhomocysteine (SAH) is significantly higher as compared to healthy individuals. Reduced methionine and SAM may reflect impaired remethylation pathway whereas increased SAH may reflect reduced S-adenosylhomocysteine hydrolase activity in the catabolic direction. Reduced SAM/SAH ratio reflects an impaired methylation capacity. We hypothesize multiple mechanisms to explain how the interplay of oxidative stress, neuroinflammation, mercury exposure, maternal use of valproate, altered gut microbiome and certain genetic variants may lead to these SAA metabotypes. Furthermore, we also propose a number of mechanisms to explain the metabolic consequences of abnormal SAA metabotypes. For instance in the brain, reduced SAM/SAH ratio will result in melatonin deficiency and hypomethylation of a number of biomolecules such as DNA, RNA and histones. In addition to previously proposed mechanisms, we propose that impaired activity of "radical SAM" enzymes will result in reduced endogenous lipoic acid synthesis, reduced molybdenum cofactor synthesis and impaired porphyrin metabolism leading to mitochondrial dysfunction, porphyrinuria and impaired sulfation capacity. Furthermore depletion of SAM may also lead to the disturbed mTOR signaling pathway in a subgroup of ASD. The proposed "SAM-depletion hypothesis" is an inclusive model to explain the relationship between heterogeneous risk factors and metabotypes observed in a subset of children with ASD.

Serum 25-hydroxyvitamin D, serum calcium and vitamin D receptor (VDR) polymorphisms in a selected population with lumbar disc herniation-A case control study.

BACKGROUND: Association of Vitamin D receptor (VDR) polymorphisms with lumbar disc herniation (LDH) have been identified in several ethnic groups globally. Despite abundant sunlight, vitamin D deficiency is reported in many tropical countries. As vitamin D is a key modulator for intestinal calcium absorption, low vitamin D could contribute to low serum calcium leading to abnormalities of skeletal homeostasis. Therefore, present study was aimed to study the association of serum 25-hydroxyvitamin D (25(OH)D), serum calcium and VDR polymorphisms in a selected Sri Lankan population. MATERIALS & METHODS: A case control study was conducted in 119 participants (cases = 51: controls = 68). Serum 25(OH)D levels were measured using ELISA. The VDR polymorphisms (Fok I and Taq I) were detected by polymerase chain reaction followed by restriction fragment length polymorphism. RESULTS: Findings indicated a significantly low (p = 0.000) 25(OH)D levels in cases (18.7±3.7 ng/mL) compared to controls(25.5±9.8 ng/mL) while 25(OH)D in both groups were below the reference range. Mean serum calcium levels in both groups were within normal reference range and was not significantly different among groups. Statistically significant association was not observed between VDR Fok I polymorphisms among cases and controls. Although Fok I polymorphism genotypes were in Hardy-Weinberg equilibrium (HWE), Taq I genotypes in controls violated HWE. CONCLUSION: Present study confirms that insufficient serum 25(OH)D levels in cases have major contribution to LDH. VDR Fok I polymorphisms did not have any significant association with LDH in Sri Lankan ethnicity.

Patterns and causes of liver involvement in acute dengue infection.

BACKGROUND: Liver involvement in acute dengue infection is frequently observed and sometimes leads to acute liver failure, with fatal outcomes. Many factors are thought to contribute to liver dysfunction, including hypoxic injury due to decreased perfusion, direct damage by the virus and immune mediated injury. In this study, we sought to identify the pattern in the change in liver enzymes throughout the illness and its association with the degree of viraemia, onset and extent of plasma leakage and inflammatory mediators. METHODS: Serial daily blood samples were obtained from 55 adult patients with acute dengue from the time of admission to discharge and the liver function tests, viral loads and cytokines were assessed. The onset and extent of fluid leakage was measured by daily ultrasound examinations and all clinical and laboratory features were serially recorded. RESULTS: Aspartate transaminase (AST), alanine transaminase (ALT) and gamma glutamyl transferase (GGT) levels were elevated in patients with dengue infection throughout the illness. The highest AST levels were seen on day 6 of illness and both AST and GGT levels were significantly higher in patients with severe dengue (SD), when compared to those with non-severe dengue (NSD) on day 5 and 6 of illness. Three patients with SD had AST and ALT values of >1000/IU in the absence of any fluid leakage or a rise in the haematocrit (≥20 %). The peak of the AST levels and the lowest serum albumin levels were seen 24 h before the maximum fluid leakage and 24 h after the peak in viraemia. Both serum IL-10 and IL-17 levels were elevated during early illness and were significantly higher in those with SD when compared to NSD. CONCLUSION: Dengue associated liver injury appears to peak around day 6 and 7. Therefore, liver function tests done at earlier dates might not reflect the extent of liver involvement in acute infection. Since severe liver involvement can occur in the absence of fluid leakage, after the peak viraemia, and since it is associated with high IL-17 and IL-10 levels, possible immune mechanisms leading to hepatic damage should be investigated.

Case control feasibility study assessing the association between severity of coronary artery disease with Glutathione Peroxidase-1 (GPX-1) and GPX-1 polymorphism (Pro198Leu).

BACKGROUND: Glutathione peroxidase-1 (GPX-1) activity was reported to be useful marker for monitoring cardiovascular disease. However, accurate assessment of coronary artery disease (CAD) using GPX-1 polymorphism is limited for South Asian population. Present study aim to assess GPX-1activity and GPX-1 polymorphismin patients with coronary artery disease (CAD) who were confirmed with coronary angiography findings and in apparently healthy subjects. METHODS: Case control study was carried out with 85 patients (58 males and 27 females) 40-60 years of age confirmed as having CAD on coronary angiography findings and 85 age and sex matched healthy volunteers as controls. Blood samples were analyzed for erythrocyte GPX-1 activity and GPX-1 polymorphism in both groups and the severity of CAD was assessed using coronary angiography scoring system based on vessel, stenosis and extent score. RESULTS: Coronary angiography scores indicated that erythrocyteGPX-1 cutoff value of 23.9 U/gHb showed a high sensitivity and negative predictive value in ruling out major vessel disease. The GPX-1 Pro198Leu (CT) polymorphism was higher in patients with CAD (25.3 %) when compared to controls (10.7 %). Pro198Leu (CT) genotype showed a 2.84 fold risk for CAD [odds ratio 2.84 (95 % CI 1.15-6.98), p = 0.019]. CONCLUSION: Coronary angiography findings indicated that individuals possessing Pro198Leu (CT) polymorphism were found to be associated with low erythrocyte GPX-1 activity and increased susceptibility for CAD.

Antioxidants in patients with dengue viral infection.

An alteration in the oxidation/reduction (redox) status of humans infected with virus infections may contrioute to tefl pariiogeiiesin anu ciniiua1 manifestations of the disease. Alterations in redox markers begin prior to the onset of clinical symptoms, suggesting early changes in the oxidant/antioxidant balance. Early identification of redox markers may be of clinical usefulness in the management of patients with dengue virus infection. We conducted a hospital based comparative cross sectional study of 55 patients serologically confirmed to have dengue infection and 55 clinically healthy age and sex matched subjects as controls to assess oxidative stress in acute dengue virus infection. Blood samples were drawn on the fifth day after symptom onset and analyzed for Trolox equivalent antioxidant capacity (TEAC), reduced glutathione (GSH), glutathione peroxidase (GPx) and paraoxonase (PON) activity. The results showed significantly lower levels of plasma TEAC, serum PON and erythrocyte GSH and GPx activity among dengue patients than in controls. Of the antioxidants investigated, PON appeared to be the most sensitive marker of oxidative stress in dengue virus infection. Serum PON may be a potentially useful marker of oxidative stress in patients with dengue virus infection.

Hemoglobin variants in patients with type 2 diabetes mellitus.

Measurement of HbA1c levels in diabetic patients is an established procedure for evaluating long-term control of diabetes. Despite its usefulness, conditions that effect hemoglobin concentration, such as hemoglobinopathies give rise to inappropriate HbA1c values. Since information about hemoglobinopathies in the diabetic population in Sri Lanka is limited, a prospective cross-sectional study was carried out among 2,695 diabetic subjects attending the diabetic clinic at Nawaloka Hospital, Sri Lanka. Hemoglobin type and HbA1c were measured by the HPLC method. The results reveal among 2,695 diabetic subjects, 53 (2%) had abnormal hemoglobin types (HbF and HbS). HbA1c concentrations in diabetic patients without Hb abnormalities show a higher correlation with fasting blood glucose than those with hemoglobin abnormalities. This study emphasizes that patients with inappropriate HbA1c values should be investigated for hemoglobinopathies.

Biochemical changes associated with reperfusion after off-pump and on-pump coronary artery bypass graft surgery.

A prospective study was performed to monitor the postoperative changes in biochemical markers associated with reperfusion injury following (i) cardiopulmonary bypass (CPB) with aortic cross-clamping and cardioplagia (CABG); (ii) CPB with a tissue stabilizing device (SUP.CPB); or (iii) surgery on beating heart (off-pump CABG or OPCABG). Of the 48 patients, 16 were subjected to CABG, 16 to SUP.CPB, and 16 to OPCABG. Arterial and venous blood samples drawn 10 min preoperatively and 0.2, 4, 24, and 48 hr after surgery were assayed for plasma lactate, total calcium, and ionized calcium and erythrocyte glutathione peroxidase (GPX) and superoxide dismutase (SOD). Results revealed that ionized calcium, SOD, and GPX levels of all patients increased at 4 hr following surgery but returned to baseline levels at 24 or 48 hr after surgery. Increased postoperative GPX levels reflect a cellular defense mechanism against oxidative damage during reperfusion, while lactate levels during reperfusion reflect delayed recovery of aerobic myocardial metabolism. The postoperative release of lactate, GPX, and SOD in patients undergoing the CABG (on-pump) technique was significantly higher compared to those subjected to OPCABG or SUP.CPB. There were no significant differences in postoperative patterns of release of biomarkers in patients with OPCABG vs SUP.CPB, suggesting that these surgical techniques are equally acceptable.

Could ochratoxin A in food commodities be the cause of chronic kidney disease in Sri Lanka?

Ochratoxin A (OA) is a naturally occurring mycotoxin with nephrotoxic properties that can contaminate plant food products. OA concentrations were assessed in commonly consumed food items in the North Central Province of Sri Lanka, where chronic kidney disease is diagnosed at epidemic proportions. Ninety-eight randomly selected food samples were analysed. Mycotoxin was detected in the extract by using a MycoMonitor Ochratoxin A ELISA assay kit (Helica Biosystems Inc., USA). The levels of OA found in these food commodities were below the recommended statutory maximum limit and are unlikely to be a potential risk factor for nephropathy in the North Central Province of Sri Lanka.

The significance of serum uric acid, creatinine and urinary microprotein levels in predicting pre-eclampsia.

The object of this study was to determine whether serum uric acid, serum creatinine and urinary microprotein levels could be used to identify women who might subsequently develop pre-eclampsia during pregnancy. This is a cross-sectional descriptive study performed on women attending the University antenatal clinic in Colombo South Teaching Hospital, Sri Lanka. Serum uric acid, creatinine and microproteinuria levels were determined in 256 women attending the antenatal clinic at 28 weeks of pregnancy. Subsequently they were followed-up at 2-weekly intervals until 36 weeks and weekly thereafter until delivery. At each visit blood pressure was recorded and serum uric acid, creatinine and microprotein levels were determined. Fifty-nine women developed blood pressures of 140/90 mmHg or more during the study period. Serum uric acid and serum creatinine levels did not show any significant difference before the elevated blood pressures were recorded. Microprotenuria levels of more than 375 mg/l were recorded in 43 women before elevation of their blood pressure. Sixty-five women of 197 who remained normotensive had microproteinuria levels of more than 375 mg/l. The sensitivity and specificity of microproteinuria levels of more than 375 mg/l as a screening test for prediction of pre-eclampsia was 73% and 67%, respectively. Therefore, microproteinuria of more than 375 mg/l may be used as a cut-off value and as a screening test for the early detection of women at risk of developing pre-eclampsia. Serum uric acid and creatinine had no predictive value as a screening test for pre-eclampsia.

Effect of exogenous histidine and Garcinia cambogia on histamine formation in skipjack (Katsuwonus pelamis) homogenates.

Histamine consumed with food gives rise to allergic reactions. Dark muscle fish, for example skipjack (Katsuwonus pelamis) has been shown to contain histamine. Studies using TLC (acetone: NH4OH, 80:20.5) on silica gel G60 plates and densitometry after spraying with ninhydrin, using a computerized densitometer, showed that freshly harvested skipjack has no detectable histamine (detection limit, 50 micrograms.g-1 fish). However, with time histamine (Rf 0.84) is formed > 1.5 mg.g-1 probably through microbial action. Skipjack contains high levels of free histidine at levels of > 10 mg.g-1 (Rf 0.41) but fish like seer (Scomberamous spp.), which are not reported to be allergenic, contain < 4 mg.g-1 histidine. Addition of exogenous histidine (50 mg.g-1) results in histamine formation in seer 2.2-fold that of skipjack under the same conditions. A type of herring (Amblygaster spp., sinhala-hurulla) is not a histamine former, but had been shown to cause allergenic reactions, resulting in a ninhydrin positive spot (Rf 0.79) on incubating for 24 hours. Addition of arginine and lysine to blended skipjack results in their loss probably by decarboxylation. Addition of the spice Garcinia cambogia (extracts 0.2 g ml-1) known as 'goraka' in Sri Lanka (sinhala) and 'kukum' in India (hindhi), to fresh skipjack incubates prevents histamine formation as a results of lowering pH to 3.2-3.6 whereas Avverhoea bilimbi (bilin) and Tamarindus indica (tamarind) extracts did not prevent histamine formation.