Organic Acidurias: An Updated Review

Organic acidurias are an important class of inherited metabolic disorders arising due to defect in intermediary metabolic pathways of carbohydrate, amino acids and fatty acid oxidation. This review summarizes the current knowledge about the important organic acidurias in the Indian population. Specifically, diagnosis and principles of treatment of organic acidurias are covered. The salient features of common organic acidurias as well as their prevalence in various parts of the world are reviewed in some detail.     

Profile of Plasma Amino Acid Levels in Rats Exposed to Acute Hypoxic Hypoxia

The effect of acute hypoxic hypoxia on the profile of plasma amino acids in rats was studied and compared to that resulting from acute liver injury induced by giving carbon tetrachloride. In hypoxic rats exposed to 45% air in N₂ for 5 h, the concentrations of branched chain amino acids, including valine, leucine and isoleucine, and aromatic amino acids such as phenylalanine and tyrosine were significantly increased as compared to those in normoxic rats. The ratio of branched-chain to aromatic amino acids (Fischer’s ratio) was significantly decreased. The levels of arginine and citrulline, which are related to the urea cycle, were also depressed. Furthermore, plasma proline level was reduced in hypoxic rats. The activities of plasma marker enzymes for tissue damage remained unchanged during hypoxia, indicating that tissue injury was not induced by exposure to hypoxic conditions. We suggest that the characteristic profile of plasma amino acids and the Fischer ratio are valuable tools for understanding the pathology of acute hypoxia in the absence of systemic tissue damage.     

Circulating Biomarkers and their Possible Role in Pathogenesis of Chronic Hepatitis B and C Viral Infections

The present study evaluated the plausible role of circulating biomarkers in immune pathogenesis of chronic hepatitis considered a priority in clinical hepatology. Total viral load of chronic hepatitis B virus (HBV) and hepatitis C virus (HCV) patients was quantified and correlation studies were performed with circulating levels of Th1/Th2 cytokines; C reactive protein and circulating nucleosomes; glutathione reductase (GR) and superoxide dismutase. To our knowledge, the study is first among its kind that validates strong positive correlation of viral load with IL-4, IL-6, GR in HBV and IL-6, IL-10, GR in HCV infections. Although, multi-centric studies including large cohorts are required for translating our findings to clinical practice, however, role of these biomarkers with potential diagnostic or prognostic significance might be helpful in clinical assessment of high-risk individuals, thereby, designing interventional strategies, towards development of personalized medicare. The results of our study also offer valuable insights of immune signaling mediators engaged in development of hepatocellular carcinoma.     

Adiponectin Gene Polymorphism and its Association with Type 2 Diabetes Mellitus

Mutations in different regions of adiponectin gene have been reported to be associated with obesity, atherosclerosis and type 2 diabetes mellitus. The present study was aimed to investigate the association among SNP 45 T > G of adiponectin gene and type 2 diabetes in South Indian population. 75 clinically diagnosed case of type 2 diabetes were studied and compared with 75 apparently healthy controls. The genotype frequency of SNP45 T > G in exon 2 of adiponectin gene was determined by PCR based restriction enzyme analysis using the restriction enzyme SmaI. (recognition site: CCC↓GGG). Three kind of genotypes: wild type TT (470 bp), heterozygous type TG (470 bp, 336 bp, 134 bp) and homozygote mutant type GG (336 bp, 134 bp) were studied. A positive association has been found between SNP45 T > G and type 2 diabetes in the study population (P = 0.010, OR = 3.797, 95% CI = 1.312–10.983). Therefore, SNP45T > G in adiponectin gene may be one of the risk factors for type 2 diabetes.     

Diagnosis of Major Organic Acidurias in Children: Two Years Experience at a Tertiary Care Centre

Organic acid disorders are inherited metabolic disorders in which organic acids accumulate in tissues and biological fluids of affected individuals. Classical organic acidurias include methylmalonic aciduria, propionic aciduria, isovaleric aciduria and maple syrup urine disease (MSUD). They are considered the most frequent metabolic disorders among severely ill children. Patients frequently present with acute symptoms early in life. 420 cases clinically suspected to have organic aciduria, with upper age limit of 12 years for a 2-year period (January 2007–December 2008) were enrolled into this study. Metabolic acidosis and neurological symptoms were the most common signs. Screening tests and thin layer chromatography were done for detection of organic acidurias. Identification and quantitation of organic acids in urine and quantification of amino acids in blood were done by high performance liquid chromatography. Out of 420 patients, 45 patients (10.7%) were found to have organic acidurias. 15 cases of methylmalonic aciduria, 16 cases of propionic aciduria, 13 cases of MSUD, and one case of isovaleric aciduria were diagnosed. Results demonstrate the importance of testing for organic acidurias. Since organic aciduria may cause irreversible brain damage if not treated, we recommend selective screening amongst severely ill children despite implied extra costs.     

Myeloperoxidase in Chronic Kidney Disease

Numerous lines of evidence implicate a role of myeloperoxidase (MPO) in the pathogenesis of cardiovascular disease (CVD). It is a well accepted fact that patients with chronic kidney disease (CKD) are at an increased risk for CVD. MPO is a pro-oxidant enzyme which could be involved in the increased susceptibility of these patients to CVD. Hence, the levels of plasma MPO was determined in healthy controls as well as in patients with CKD [stratified with the level of their kidney failure as CKD stages II–V (end stage renal disease)]. Plasma MPO was assayed by a spectrophotometric method. Serum urea and creatinine were estimated on a clinical chemistry analyzer using standard laboratory procedures. The mean plasma MPO levels were significantly lower with advancing stages of renal failure (P < 0.001). There was a positive correlation between MPO and GFR (r = +0.89, P < 0.001) and a negative correlation with urea (r = −0.85, P < 0.001) and creatinine (r = −0.82, P < 0.001). While an inverse association was observed between plasma MPO and urea in CKD patients, such an association was not observed in control subjects (P = 0.43). In conclusion, the decline in plasma MPO levels may be due to the inhibitory effect of uraemic toxins on the enzyme.     

Diagnostic Dilemma of HbA1c Detection in Presence of a Hemoglobinopathy: A Case Report

We report a case of a diabetic, heterozygote with near normal hematology, marginally low level of hemoglobin A₂(HbA₂) having an increased level of hemoglobin F(HbF) that was pancellularly distributed among the red cells. BioRad DiaSTAT measurements gave a high glycated hemoglobin A1c(HbA1c) of 31.5% and the BioRad Variant analyzer recorded an HbA1c value which was very low, in discordance with the detected blood glucose levels. Flow cytometry and polymerization chain reaction (PCR) based studies were carried out which revealed the case to be that of the common hereditary persistence of fetal hemoglobin (HPFH)-3, an Asian Indian mutation. Fructosamine estimation and HbA1c by Boronate affinity chromatography were able to resolve the discordant value detected and was able to confirm the diabetes status. The case would have been a diagnostic dilemma, if reported without correlation.