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Biomedical subjects

A K Das

Publications and source records attributed to A K Das.

At least 109 records · Page 6Linked to original sources

Diet and lifestyle guidelines and desirable levels of risk factors for the prevention of diabetes and its vascular complications in Indians: a scientific statement of The International College of Nutrition. Indian Consensus Group for the Prevention of Diabetes.

BACKGROUND: There has been a rapid increase in the prevalence of diabetes and cardiovascular disease in India, in association with rapid changes in diet and lifestyle. In adults, the prevalence of diabetes, hypertension and coronary artery disease is two- to threefold greater in the urban population than in rural populations; it is associated with modest insulin resistance in urban groups. METHODS: In response to a proposal by the International College of Nutrition that specialist experts should develop consensus recommendations for the prevention of chronic diseases, Indian specialists in diabetes and vascular disease have collaborated to produce guidelines relevant to the population of India. RECOMMENDATIONS: Because Indian urban populations have a modest increase in overweight and low rates of obesity in association with the rapid emergence of diabetes and cardiovascular risk, a body mass index of 21 kg/m2 should be considered safe, with a range of 19-23 kg/m2 acceptable; > 23 kg/m2 should be considered overweight, and > 25 kg/m2 should be taken to indicate obesity. A waist:hip ratio > 0.88 in males and > 0.85 in females should be considered to indicate central obesity, because the prevalence of coronary disease, hypertension and associated disturbances of insulin resistance are more common above these limits. For the prevention of vascular disease, there is general international consensus that the desirable serum concentration of cholesterol should be < 170 mg/dl (> 4.42 mmol/l), which may also be optimal for Indians; values between 170 and 200 mg/dl (4.42-5.2 mmol/l) should be considered borderline. The critical values for low density lipoprotein cholesterol may be < 90 mg/dl (ideal), 90-110 mg/dl (borderline high) and > 110 mg/dl (high) (< 2.32, 2.32-2.84 and > 2.84 mmol/l, respectively). Fasting triglycerides should be < 150 mg/dl (< 1.69 mmol/l) and high-density lipoprotein cholesterol > 35 mg/dl (> 0.9 mmol/l). The limit for the total energy derived from fat intake should be < 21%/day (7% each for saturated, polyunsaturated and mono-unsaturated fatty acids). The carbohydrate intake should provide more than 65% of daily energy, mainly from complex carbohydrates. A daily dietary intake of 400 g fruits, vegetables and legumes, 400 g cereals, in conjunction with 25 g soya bean or mustard or canola oils (rich in n-3 fatty acids) in place of fats rich in saturated fat, may be protective against diabetes and vascular disease. Moderate physical activity with the aim of burning 300 Kcal/day (> 1255 KJ/day), and cessation of tobacco and alcohol consumption, may provide an effective programme for prevention of diabetes and its vascular complications in Indians.

Adult↗

Crystal structure of the protein serine/threonine phosphatase 2C at 2.0 A resolution.

Protein phosphatase 2C (PP2C) is a Mn2+- or Mg2+-dependent protein Ser/Thr phosphatase that is essential for regulating cellular stress responses in eukaryotes. The crystal structure of human PP2C reveals a novel protein fold with a catalytic domain composed of a central beta-sandwich that binds two manganese ions, which is surrounded by alpha-helices. Mn2+-bound water molecules at the binuclear metal centre coordinate the phosphate group of the substrate and provide a nucleophile and general acid in the dephosphorylation reaction. Our model presents a framework for understanding not only the classical Mn2+/Mg2+-dependent protein phosphatases but also the sequence-related domains of mitochondrial pyruvate dehydrogenase phosphatase, the Bacillus subtilus phosphatase SpoIIE and a 300-residue domain within yeast adenyl cyclase. The protein architecture and deduced catalytic mechanism are strikingly similar to the PP1, PP2A, PP2B family of protein Ser/Thr phosphatases, with which PP2C shares no sequence similarity, suggestive of convergent evolution of protein Ser/Thr phosphatases.

Adenylyl Cyclases↗

Zinc and iron as bioindicators of precancerous nature of oral submucous fibrosis.

Oral Submucous Fibrosis (OSF) is a precancerous condition of oral cavity and oropharynx. Its etiopathogenesis is still obscure. Epithelial dysplasia is considered an important indicator of it. In the present study, the authors try to ascertain bioinorganic parameters as alternate indicators of malignant potential of OSF along with other clinicopathological attributes. They also try to identify causative factors. Thirty-six OSF patients, showing different degrees of epithelial dysplasia, and 12 normal individuals are studied with special reference to trace metal contents (Zn and Fe) in oral tissues. Statistical analyses of data indicate that trace metal contents can be regarded as an alternate indicator of the precancerous nature of OSF. Some clinicopathological attributes that are easier and cheaper to measure may also indicate OSF.

Adult↗

Determination of cadmium by electrothermal atomic absorption spectrometry after microwave-assisted digestion of animal tissues and sewage sludges.

The determination of cadmium in different sample types has been carried out by electrothermal atomization atomic absorption spectrometry with D(2)-background correction using a unpyrocoated graphite tube, after pressurized microwave-assisted digestion. Five chemical modifiers [(NH(4))(2)HPO(4), Pd(NO)(3))(2), Ni(NO(3))(2), thiourea and Triton X-100] have been assayed and nickel nitrate has been found to be most effective for an accurate determination of cadmium in mussel tissue, pig kidney and sewage sludge. The characteristic mass of the method is of the order of 1 pg and the limit of detection is lower than 0.1 ng/ml.

Journal Article↗

Literature study of microwave-assisted digestion using electrothermal atomic absorption spectrometry.

The literature on the use of microwave-assisted digestion procedures for subsequent sample analysis by means of electrothermal atomic absorption spectrometry (ETAAS) is reviewed. The literature survey reveals that this digestion technique has been applied mainly for biological materials. The elements most extensively determined by this method are cadmium and lead followed by copper, chromium, nickel and iron. The microwave digestion conditions, ETAAS furnace programmes and analytical details of the developed methodologies have been carefully revised.

Journal Article↗

Determination of manganese in environmental samples (e.g. coal fly ash) by electrothermal AAS after its separation with a liquid chelating ion exchanger.

An electrothermal atomic absorption spectrometric method is described for the determination of manganese in various coal fly ash samples after its separation with dissolved monothioxo-beta-diketone as chelating ion exchanger. The detection limit is 1 ng ml(-1). To study the accuracy of the method, a reference material of similar composition was analysed and recovery of spiked manganese was performed.

Journal Article↗

Primary tumors of the aorta.

Primary tumors of the aorta are rare and are usually malignant. Thirty-three cases are reported in the world literature, of which 2 are myxomas. The diagnosis is difficult and is commonly made postoperatively or at autopsy. We present a case of intraluminal aortic myxoma that presented as recurrent arterial emboli and was managed successfully. This case showed the sensitivity of magnetic resonance imaging and transesophageal echocardiography in diagnosis.

Adult↗

Inorganic arsenic species in groundwater: a case study from Purbasthali (Burdwan), India.

A regional groundwater quality survey from 20 tube wells in the Purbasthali area of the Burdwan district of West Bengal province (India) identified arsenic pollution in this area. Arsenic was detected in 19 cases at a concentration level 0.5 to 135.9 micrograms/L. Speciation studies indicate that As(III) is present in only one sample and organo-arsenic compounds have not been detected. Iron, antimony and pH of such water samples were also studied to see if there is any correlation of the presence of arsenic and these parameters. A high concentration of iron (0.3 to 10.7 mg/L) has been detected. Antimony is present in all these water samples (0.03 to 0.9 microgram/L). The pH value of the groundwater in this area shows that it is more or less neutral.

Arsenic↗

Glomerular basement membrane thickness - a comparison of two methods of measurement in patients with unexplained haematuria.

BACKGROUND: Thin glomerular basement membranes may be an important cause of microscopic haematuria. Unfortunately measurements are often not made because of the complicated methods currently employed. METHODS: A simplified method of measurement of glomerular basement membrane thickness, involving only 16 selected measurements on a single glomerulus, was compared with the accepted, but time-consuming, orthogonal intercept technique. Thirty-one needle biopsies from patients with renal haematuria unexplained by conventional histology and immunofluorescence were studied. Measurements were made on the same ultrathin sections. RESULTS: The new method was found to give much lower values (mean (SD) 202+/-51 versus 282+/-52 nm) with limits of agreement of -131 to -30 nm compared with the orthogonal intercept method. The coefficient of repeatability was 39 nm for the orthogonal intercept method and 56 nm for the new method. However, using two glomeruli the new method had limits of agreement of -120 to -41 nm with a coefficient of repeatability of 38 nm. CONCLUSIONS: Provided two glomeruli are measured the new technique is sufficiently accurate for the diagnosis of thin membrane nephrology, in appropriate cases, and is much simpler and cheaper than the orthogonal intercept method.

Adolescent↗

A novel chemical synthesis of 1-O-hexadecyl-rac-[2-3H]glycero-3-phosphorylethanolamine and a simple assay for plasmanyl desaturase.

A simple and efficient method for chemical synthesis of lysophosphatidylethanolamine is described. 1-O-hexadecyl diazohydroxyacetone (A. K. Hajra, T. V. Saraswathi and A. K. Das. 1983. Chem. Phys. Lipids. 33: 179-193) was decomposed by benzyloxycarbonyl (CBZ) derivative of phosphorylethanolamine (I) to give 1-O-hexadecyl dihydroxyacetone-3-(N)-CBZ phosphorylethanolamine (II). Compound (II) was reduced by NaBH4 and the product (III), after catalytic transfer hydrogenolysis produced the final compound, 1-O-hexadecyl-rac-glycero-3-phosphorylethanolamine (IV). The yield of (IV), starting from 1-O-hexadecyl diazohydroxyacetone was 53%. The identities of the compounds were verified by NMR and fast atom bombardment mass spectral (FAB-MS) analysis. 1-O-hexadecyl-rac[2-3H]glycero-3-phosphorylethanolamine prepared by the method above was shown to be a good in vitro substrate for plasmanyl delta 1'-desaturase (EC 1.14.99.19). Using this radioactive substrate, a simple and rapid solvent partition assay for this enzyme was developed with results comparable to those obtained by the two-dimensional thin-layer chromatographic assay method. The advantage of this rapid assay system and the applicability of the chemical synthetic method for other phosphoglycerides are discussed.

Biological Assay↗

Clubbing--a reevaluation of its incidence and causes.

117 adult patients (age > 13 years) admitted in medical wards were studied for clubbing. 24.8% (29/117) of the patients had clubbing. Incidence of clubbing in males and females was 22.2% (26/117) and 2.6% (3/117) respectively [corrected]. Liver disease, which was seen in 27.6% cases (8/29) of clubbing, was the commonest cause of clubbing and was observed only in males. This was related to a high incidence of alcohol intake among males i.e. 34.6% (9/26) as against none among the females. Amongst the liver disease, suppurative liver disease was responsible for clubbing in 75% (6/8) of cases. Only 20.7% (6/29) of patients with clubbing had severe clubbing. 66.6% (4/6) of patients with severe clubbing had liver disease. Congenital heart disease was cause of clubbing in 2 out of 3 females (66.6%) with clubbing. Alcohol may be causally related to occurrence of clubbing in this part of the country.

Adolescent↗

Clinical and laboratory profile of sixty patients with AIDS: a South Indian study.

Sixty patients who fulfilled the WHO case definition of acquired immunodeficiency syndrome (AIDS) were admitted and treated between January 1993 and June 1995 in JIPMER Hospital, Pondicherry, South India. Their mean age was 30.3 +/- 6.4 years. Male: female ratio was 5 : 1. The heterosexual route was the major mode of transmission (96.7%). Fever was the commonest presentation (98.3%), followed by weight loss (85%) and cough (36.7%). The commonest opportunistic infection seen was tuberculosis (pulmonary, extrapulmonary - single or in combination) followed by esophageal candidiasis. Cryptococcal meningitis, intestinal crytosporidiosis, CNS toxoplasmosis, Pneumocystis pneumonia and group B Salmonella septicemia were the other infections encountered. Ten out of the 38 patients with tuberculosis were followed up on antituberculous treatment for 6 months. Seven out of 18 patients with esophageal candidiasis were treated with ketoconazole.

Acquired Immunodeficiency Syndrome↗

A comparison of the temporal expressiveness of three database query methods.

Time is a multifaceted phenomenon that developers of clinical decision-support systems can model at various levels of complexity. An unresolved issue for the design of clinical databases is whether the underlying data model should support interval semantics. In this paper, we examine whether interval-based operations are required for querying protocol-based conditions. We report on an analysis of a set of 256 eligibility criteria that the T-HELPER system uses to screen patients for enrollment in eight clinical-trial protocols for HIV disease. We consider three data-manipulation methods for temporal querying: the consensus query representation Arden Syntax, the commercial standard query language SQL, and the temporal query language TimeLineSQL (TLSQL). We compare the ability of these three query methods to express the eligibility criteria. Seventy nine percent of the 256 criteria require operations on time stamps. These temporal conditions comprise four distinct patterns, two of which use interval-based data. Our analysis indicates that the Arden Syntax can query the two non-interval patterns, which represent 54% of the temporal conditions. Timepoint comparisons formulated in SQL can instantiate the two non-interval patterns and one interval pattern, which encompass 96% of the temporal conditions. TLSQL, which supports an interval-based model of time, can express all four types of temporal patterns. Our results demonstrate that the T-HELPER system requires simple temporal operations for most protocol-based queries. Of the three approaches tested, TLSQL is the only query method that is sufficiently expressive for the temporal conditions in this system.

Decision Making, Computer-Assisted↗

Knowledge-based temporal abstraction in diabetes therapy.

We suggest a general framework for solving the task of creating abstract, interval-based concepts from time-stamped clinical data. We refer to this problem-solving framework as the knowledge-based temporal-abstraction (KBTA) method. The KBTA method emphasizes explicit representation, acquisition, maintenance, reuse, and the sharing of knowledge required for abstraction of time-oriented clinical data. We describe the subtasks into which the KBTA method decomposes its task, the problem-solving mechanisms that solve these subtasks, and the knowledge necessary for instantiating these mechanisms in a particular clinical domain. We have implemented the KBTA method in the RESUME system and have applied it to the task of monitoring the care of insulin-dependent diabetics.

Artificial Intelligence↗