Biomedical subjects
D Singh
Publications and source records attributed to D Singh.
Clinical profile and therapy in enteric fever.
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Diazo test in typhoid fever.
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Stressful family life events and parental perception of poor appetite in children.
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Incidence of coxsackie (B) virus infection in diabetics.
45 diabetic patients were screened for raised titres against Coxsackie group of viruses. 11 diabetic patients showed raised titres of neutralising antibodies against one of the coxsackie group of viruses, as against 3 in 25 controls.
DNA fingerprinting and the substantive law.
The ability to analyse human DNA has the potential to revolutionize legal proceedings--both civil and criminal--especially those which turn on biological or genetic evidence. Examining the positive and negative aspects of DNA fingerprinting, it would appear that the benefits certainly outweigh any disadvantages. In paternity determinations, DNA fingerprinting renders otiose many of the controversial concerns, particularly regarding the determination of legal probability, providing as it does unequivocal evidence of blood relationship. Furthermore, in criminal law, its value is well-documented. The relevant legislation is already in place, therefore no further legislation is required to enable South African law enforcement agencies to make use of the DNA test. The apparently high cost may, however, frustrate its general application to the civil law but with the assistance of the state and law societies, the envisaged problem could be alleviated. To date no other forensic tests rival the accuracy of the DNA test.
Colobronchial fistula: an unusual complication of Crohn's disease.
Fistulas secondary to Crohn's disease occur in about 33% of patients. A colobronchial fistula complicating Crohn's disease is very rare, having been reported only twice previously. We present an unusual fistula secondary to Crohn's colitis that originated from the splenic flexure and crossed the diaphragm to involve the bronchial tree.
Effect of glycosphingolipid fatty acid chain length on behavior in unsaturated phosphatidylcholine bilayers: a 2H NMR study.
Deuterium-labeled glycosphingolipids, N-lignoceroyl[d47]galactosylceramide (24:0 fatty acid form) and N-stearoyl[d35]galactosylceramide (18:0 fatty acid form) were prepared by partial synthesis. These probe-labeled species, differing only in the lengths of their fatty acids, were compared via 2H NMR with regard to arrangement and behavior in bilayers of the monounsaturated phospholipid 1-stearoyl-2-oleoylphosphatidylcholine (SOPC). Results were used to consider the physical significance of the great range of common acyl chain lengths that is a frequent feature of cell membrane glycosphingolipids. N-lignoceroyl[d47]- and N-stearoyl[d35]galactosylceramide were incorporated at concentrations ranging from 5 to 50 mol % into unsonicated phospholipid liposomes, and their spectra were analyzed in the range +73 to -14 degrees C. For the 18:0 fatty acid derivative, first spectral moments, M1, were calculated and plotted as a function of temperature for each sample composition. Spectral inspection for regions of phase coexistence, in conjunction with consideration of M1 curves, permitted derivation of phase diagram boundaries which were then refined using spectral subtraction techniques. The phase diagram for galactosylceramide with short fatty acid in SOPC was compared to the corresponding phase diagram for its long-chain analogue, derived previously in the same fashion [Morrow, M. R., Singh, D., Lu, D., & Grant, C. W. M. (1992) Biochim. Biophys. Acta 1106, 85-93]. The binary phase diagrams referred to above, which reflect the behavior of short- and long-chain glycolipids in a common phospholipid host matrix, displayed important similarities and differences. In fluid membranes, the behavior appeared to be remarkably alike, as reflected in superimposable fluidus curves over the concentration range studied.(ABSTRACT TRUNCATED AT 250 WORDS)
Nutrient composition and electrophoretic pattern of protein in two distinct types of phalsa (Grewia subinequalis DC).
Two distinct types, i.e. tall and dwarf types of phalsa, were studied for the differences in their physical parameters, chemical compositions and electrophoretic patterns of seed proteins by SDS-PAGE. The two types did not show any remarkable variation in their fruit weight, edible portion, seed weight and juice yield. Tall type had higher content of reducing sugars whereas total and non-reducing sugars were higher in drawf one. Qualitative analysis revealed the presence of sucrose and fructose in both the types whereas glucose was present only in tall one. Observed marked variations in the protein content of the fruit could be due to the differences in protein content of the seed rather than that of the pulp. Electrophoretic pattern of seed proteins revealed the complete absence of two protein bands of molecular weight 37, and 59 kD from the dwarf type.
Glycosphingolipid acyl chain orientational order in unsaturated phosphatidylcholine bilayers.
The glycosphingolipid, galactosyl ceramide (GalCer), was studied by 2H nuclear magnetic resonance (NMR) in fluid phospholipid bilayer membranes, with regard to arrangement of its acyl chain. For this purpose, species with perdeuterated 18-carbon fatty acid (18:0[d35]GalCer) or with perdeuterated 24-carbon fatty acid (24:0[d47] GalCer) were dispersed in bilayers of the 18-carbon phospholipid, 1-stearoyl-2-oleoyl-phosphatidylcholine (SOPC). For 18:0[d35] GalCer, smoothed profiles of the order parameter, SCD, were found to be very similar to one another over the range of glycolipid concentration, 5-40 mol%. In addition, they were very similar to orientational order parameter profiles well known from the literature on phospholipid and glycolipid acyl chains (which deals in general with membranes of homogeneous chain length in the range 14-18 carbons). Corresponding order parameter profiles for the long-chain species, 24:0[d47] GalCer, were also similar to one another for glycolipid concentrations between 5 and 40 mol%. Their shapes, however, were distinctly different from those of the shorter chain analogues. SCD profiles for the two species were quantitatively similar to a membrane depth of C15. SCD values at C16 and C17 were approximately 20 and 30%, respectively, higher for the long-chain glycosphingolipid than for its short-chain analogue in SOPC. Nitroxide spin labels attached rigidly to C16 of the long-chain glycolipid in SOPC gave electron paramagnetic resonance (EPR) order parameters that were twice as high as for a spin label at C16 on the shorter chain glycolipid. Comparison was made between spectra of 24:0[d47] GalCer in SOPC and fully hydrated bilayers of the pure 24:0[d47] GalCer, a system that is considered to be partially interdigitated in fluid and gel phases. The resultant 2H NMR order parameter profiles displayed similar features, indicating that related organizational properties exist in these fluid systems. Effective chain length of 24:0[d47] GalCer within the SOPC membrane was calculated using the method of Schindler and Seelig (1975. Biochemistry, 14:2283-2287). The result suggested that the long-chain fatty acid should protrude roughly one third of the host matrix chain length across the bilayer midplane. However, a treatment of the same order parameters making very few assumptions about chain conformation indicated a high degree of orientational flexibility for the "extra" length of the long chain fatty acid. It seems likely that a realistic treatment of the long-chain fatty acidin a shorter chain fluid host matrix considers interdigitation as a subset of the conformational possibilities, many of which are rapidly interconverting on the NMR timescale of 10-4_10-5 s and longer lived on the EPR timescale of 10-8_10-9 s.
Adaptive significance of female physical attractiveness: role of waist-to-hip ratio.
Evidence is presented showing that body fat distribution as measured by waist-to-hip ratio (WHR) is correlated with youthfulness, reproductive endocrinologic status, and long-term health risk in women. Three studies show that men judge women with low WHR as attractive. Study 1 documents that minor changes in WHRs of Miss America winners and Playboy playmates have occurred over the past 30-60 years. Study 2 shows that college-age men find female figures with low WHR more attractive, healthier, and of greater reproductive value than figures with a higher WHR. In Study 3, 25- to 85-year-old men were found to prefer female figures with lower WHR and assign them higher ratings of attractiveness and reproductive potential. It is suggested that WHR represents an important bodily feature associated with physical attractiveness as well as with health and reproductive potential. A hypothesis is proposed to explain how WHR influences female attractiveness and its role in mate selection.
Altered sensory function and balance in older persons.
The effects of three different visual inputs (eyes open, eyes closed, and inaccurate) while standing on an unstable surface (respectively, UEO, UEC, UI) were compared in a group of healthy elderly community dwellers (N = 239; mean age 76) and young (N = 34; mean age 34) adults. Subjects with medical factors known to affect balance were excluded. Body sway and loss of balance measured dynamic force platform (EquiTest, NeuroCom International). Visual and somatosensory inputs were rendered inaccurate through tilting of the standing surface and/or the visual surround proportional to the subject's angle of sway (sway-referencing). The elderly group had significantly more difficulty balancing during UEC and UI, and a larger proportion lost their balance during UI. These findings are compared to those of other dynamic posturography studies in which sensory inputs were controlled. Issues of age, frailty, screening, and test protocol are addressed in order to account for differences in results among studies.
Citrobacter septicemia in neonates.
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Behaviour of a glycosphingolipid with unsaturated fatty acid in phosphatidylcholine bilayers.
N-(Oleoyl)galactosylceramide with perdeuterated acyl chain was prepared by partial synthesis, and studied by wide line 2H-NMR in phospholipid liposomes. Spectra were obtained for low glycolipid concentrations in bilayers of dimyristoyl-, distearoyl-, and 1-palmitoyl-2-oleoylphosphatidylcholines. In an attempt to isolate the effects of glycosphingolipid fatty acid cis unsaturation on glycolipid behaviour in membranes, spectral findings related to the above species were compared to literature NMR data for pure 1-palmitoyl-2-oleoylphosphatidylcholine bilayers in which the oleoyl chain of the phospholipid had been deuterated, and to analogously deuterated glycerol based lipids in Acholeplasma laidlawii membranes. The results for N-(oleoyl-d33)galactosylceramide proved to be qualitatively and quantitatively very similar to published data dealing with glycerol based lipids at comparable temperatures. In addition, the results were strikingly similar for glycolipids dispersed in saturated and unsaturated phospholipid host matrices. It would appear that the primary effects of cis 9,10 fatty acid unsaturation in glycosphingolipids (at low concentration in fluid phospholipid membranes) are the same as those of fatty acid cis unsaturation in glycerolipids. It further appears that the overall dynamic behaviour of N-(oleoyl)galactosylceramide in fluid phospholipid membranes is very similar to that of glycerolipids with comparable acyl chains.
Glycosphingolipid phase behaviour in unsaturated phosphatidylcholine bilayers: a 2H-NMR study.
2H-NMR was employed to consider the arrangement of a glycosphingolipid, N-(lignoceroyl-d47)galactosylceramide, in bilayers of the mono-unsaturated phospholipid, 1-stearoyl-2-oleoylphosphatidylcholine. The deuterated glycolipid prepared by partial synthesis was incorporated at concentrations ranging from 5 mol% to 53 mol% into unsonicated liposomes, and its spectra were recorded from +76 degrees C to -10 degrees C. First spectral moments were plotted as a function of temperature for each sample composition and, along with inspection of the spectra, were employed to infer a phase diagram describing glycolipid behaviour in the unsaturated phospholipid host matrix. It was possible to refine the result using 2H-NMR difference spectroscopy. The phase diagram obtained was indicative of peritectic behaviour. At glycolipid concentrations exceeding about 20 mol% there was considerable tendency to glycolipid phase separation--as indicated by coexistence of fluid phospholipid-enriched and gel phase glycolipid-enriched domains over a wide range of temperatures, and by coexistence of distinct ordered phase domains at lower temperature. In contrast, at lower glycolipid concentrations reflective of many biological membranes, the lipid components were miscible in both the liquid crystal and gel phases, with only a narrow temperature range of fluid and ordered phase coexistence. For the fluid phase at low glycolipid concentrations, spectra of the deuterated glycolipid 24-carbon fatty acid suggest that orientational order is low for a number of methylene groups near the methyl end of the chain.
Equilibrium geometry and electronic structure of the low-temperature W(001) surface.
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