Marchiafava Bignami disease.
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Alcohol Drinking↗
Biomedical subjects
A K Joshi
Publications and source records attributed to A K Joshi.
The bacterial periplasmic histidine-binding protein. structure/function analysis of the ligand-binding site and comparison with related proteins.
Bacterial periplasmic binding proteins are initial receptors in the process of active transport across cell membranes and/or chemotaxis. Among them, the histidine-binding protein (HisJ) has been extensively studied from the biochemical, physiological, and genetic points of view. The three-dimensional crystal structure of the histidine-binding protein complexed with histidine has been determined at 2.5-A resolution by the molecular replacement method using a probe structure the previously solved lysine-liganded structure of the lysine-, arginine-, ornithine-binding protein (LAO), which shares 70% sequence identity with HisJ. The structure is bi-lobate; the two lobes, one bigger than the other, are connected by two short strands and are in contact with each other (closed) enclosing the histidine. Charged, polar, and non-polar side chains, as well as the peptide backbone, are involved in tight binding of the histidine. The bound histidine is involved in eight direct hydrogen bonds, six with the bigger lobe and two with the smaller lobe, in one potential water-mediated hydrogen bond with the bigger lobe, as well as in ionic interactions. The HisJ residues surrounding the ligand are the same as the LAO residues interacting with lysine, except for residue 52 which is leucine in HisJ and phenylalanine in LAO. The Leu-52 in HisJ makes a hydrophobic interaction with the imidazole ring of histidine. Of seven mutations affecting the ligand-binding site, five are located in the ligand-binding site, one in a connecting strand, and one at the domains interface. Based on comparisons among related binding proteins, the specific interactions between the ligands and the respective binding protein residues are predicted for the glutamine-binding protein and the opines-binding protein.
Bacterial Proteins↗
Lipoprotein lipids and the prevalence of hyperlipidaemia in rural India.
BACKGROUND: The prevalence of hyperlipidaemias has been inadequately studied in rural populations of developing countries. No significant data exist on the population levels of serum cholesterol, cholesterol subclasses or triglycerides in these countries. METHODS: We studied fasting blood samples of 300 apparently healthy adults (202 men and 98 women, age range 20-73 years) randomly selected from a larger sample of 3148 individuals during a comprehensive cardiovascular risk-factor survey in Rajasthan, India. Levels of serum total cholesterol, its subfractions [low-density-lipoprotein (LDL) cholesterol, very-low-density-lipoprotein cholesterol and high-density-lipoprotein (HDL) cholesterol] and triglycerides were measured and correlated with age and anthropometric data. RESULTS: The mean +/- SD serum total-cholesterol levels were 4.39 +/- 1.0 mmol/l in men and 4.37 +/- 1.0 mmol/l in women, the mean LDL-cholesterol levels 2.51 +/- 1.0 mmol/l in men and 2.62 +/- 0.9 mmol/l in women, the mean HDL-cholesterol levels 1.15 +/- 0.4 mmol/l in both mean and women and the mean fasting serum triglyceride levels 1.63 +/- 0.6 mmol/l in men and 1.48 +/- 0.7 mmol/l in women. Age correlated positively with total-cholesterol, LDL-cholesterol, HDL-cholesterol and triglyceride levels in both men and women. Levels of the cholesterol subtypes did not differ between the sexes (P > 0.01), although triglyceride levels were significantly higher in men (P < 0.01). Lipoprotein lipids did not correlate significantly with height, weight, body-mass index or waist:hip ratio. When classified according to the recommendations of the US National Cholesterol Education Program for the determination of the prevalence of hyperlipidaemia, 43 individuals (14.3%; men 14.4% and women 14.3%) had borderline high cholesterol levels (5.20-6.18 mmol/l) and 24 (8%; men 7.9% and women 8.2%) had high cholesterol levels (> or = 6.21 mmol/l). Forty-five participants (15%) had borderline high LDL-cholesterol levels (3.36-4.11 mmol/l) and 20 (6.7%) had high LDL-cholesterol levels (> or = 4.14 mmol/l); low HDL-cholesterol levels (< 0.9 mmol/L) were found in 89 (29.7%). Eighteen participants (6%) had mild hypertriglyceridaemia (2.82-5.64 mmol/l) and two (0.7%) had severe hypertriglyceridaemia (> 5.64 mmol/l). CONCLUSION: Total-cholesterol and LDL-cholesterol levels are low in a rural Indian population, although an atherogenic lipid profile is present in a significant proportion.
Adult↗
Construction of a cDNA encoding the multifunctional animal fatty acid synthase and expression in Spodoptera frugiperda cells using baculoviral vectors.
A cDNA encoding the 2505-residue multifunctional rat fatty acid synthase has been constructed and expressed as a catalytically active protein in Spodoptera frugiperda (Sf9) cells using Autographa californica nuclear polyhedrosis virus (baculovirus). The 7.5 kb cDNA was engineered by the amplification and sequential splicing together of seven fragments contained in overlapping cDNAs that collectively spanned the entire rat fatty acid synthase coding sequence. The full-length cDNA was cloned into a baculoviral transfer vector and used together with linearized baculoviral DNA to co-transfect Sf9 cells. Recombinant viral clones were purified and identified by Western blotting. The recombinant fatty acid synthase was expressed maximally 2 days after infection of the Sf9 cells, constituting up to 20% of the soluble cytoplasm, and could be conveniently separated from the insect host fatty acid synthase by high-performance anion-exchange chromatography. The catalytic properties of the purified recombinant fatty acid synthase are indistinguishable from those of the best preparations of the natural protein obtained from rat liver. These results indicate that, in the insect cell host, all seven catalytic components of the 2505-residue recombinant fatty acid synthase fold correctly, the acyl-carrier-protein domain is appropriately phosphopantetheinylated post-translationally, and the multifunctional polypeptide forms catalytically competent dimers. Thus the baculoviral system appears to be well suited for the expression of specific fatty acid synthase mutants that can be used to explore the mechanism by which the seven domains of this multifunctional homodimer co-operate in the biosynthesis of fatty acids.
Amino Acid Sequence↗
Construction, expression, and characterization of a mutated animal fatty acid synthase deficient in the dehydrase function.
The location of the dehydrase domain in the multifunctional animal fatty acid synthase has been determined by engineering a fatty acid synthase mutant deficient in dehydrase activity. A full-length fatty acid synthase cDNA encoding a mutated histidine residue (His878-->Ala) was constructed and expressed in insect Sf9 cells using a baculoviral vector. The mutated recombinant fatty acid synthase retained all partial activities of the multifunctional complex except the dehydrase and was unable to synthesize fatty acids. beta-Hydroxybutyryl moieties were formed by the mutant fatty acid synthase from acetyl-CoA, malonyl-CoA, and NADPH and slowly released as the CoA thioester, confirming that this protein cannot perform the dehydration reaction. This finding points to an important catalytic role for His878 in the dehydration reaction and establishes that the dehydrase domain is located immediately adjacent to the carboxyl terminus of the transferase domain. Examination of the completed domain map for the animal fatty acid synthase indicates that the catalytic domains are clustered in two groups separated by a central structural core: the ketoacyl synthase, malonyl/acetyltransferase, and dehydrase in the amino-terminal half and the enoyl reductase, ketoreductase, acyl carrier protein, and thioesterase in the carboxyl-terminal half. A model is proposed in which the two centers for acyl chain initiation, elongation and termination, are formed by the cooperation of the three amino-terminal domains of one subunit with the four carboxyl-terminal domains of the other subunit.
Alanine↗
Calculation of antibody and antigen concentrations from ELISA data using a graphical method.
A graphical method for determining the concentration of either the antibody or the antigen from ELISA data is presented in the form of a GWBASIC program. In the program, ELISAEQ, optical densities (OD) obtained from a 96-well ELISA plate can be input either directly by interfacing a microplate reader to the computer or manually. The program uses standard sample data, and selects the semilogarithmic linear range. Over this range, a least-squares method is used to determine the concentrations of interest. In addition, a hyperbolic interpolation formula is derived over the entire range for estimating the antibody or antigen concentration of the unknown samples whose OD is beyond the linear range.
Antibodies↗
Rapid polymerase chain reaction amplification using intact bacterial cells.
We have demonstrated that efficient polymerase chain reaction amplifications from chromosomal DNA can be carried out using whole bacterial cells as the starting material. Cells from the liquid or solid cultures can be used directly, without any pre-treatment, thus eliminating the need for DNA isolation.
ATP-Binding Cassette Transporters↗
Energy coupling in bacterial periplasmic permeases.
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Adenosine Triphosphatases↗
Energy coupling in bacterial periplasmic transport systems. Studies in intact Escherichia coli cells.
Periplasmic permeases are composed of four proteins, one of which has an ATP-binding site that has been postulated to be involved in energy coupling. Previous data suggested that these permeases derive energy from substrate level phosphorylation (Berger, E. A. (1973) Proc. Natl. Acad. Sci. U.S.A. 70, 1514-1518); however, conflicting results later cast doubt upon this hypothesis. Here, we make use of two well characterized periplasmic permeases and of a well characterized unc mutant (ATPase-) to examine this energetics problem in depth. We have utilized the histidine and maltose periplasmic permeases in Escherichia coli as model systems. Isogenic unc strains were used in order to study separately the effect of the proton-motive force and of ATP on transport. These parameters were analyzed concomitantly with transport assays. Starvation experiments indicate that both histidine and maltose transport require ATP generation and that a normal level of delta psi is not sufficient. Uncouplers such as carbonyl cyanide-m-chlorophenylhydrazone and 2,4-dinitrophenol dissipated the delta psi without decreasing the ATP level and without significant effect on these permeases, showing that delta psi is not needed. Inhibition of ATP synthesis by arsenate eliminates transport through both permeases, confirming the need for ATP. In agreement with previous results with the glutamine permease (Plate, C. A. (1979) J. Bacteriol. 137, 221-225), valinomycin plus K+ dissipates delta psi without affecting ATP levels and inhibits histidine transport; however, maltose transport is not inhibited under these conditions. This result is discussed in terms of the artefactual side effects caused by valinomycin/K+ treatment on some periplasmic permeases. Histidine transport is also shown to be sensitive to changes in the cytoplasmic pH. It is concluded that periplasmic permeases indeed have an obligatory requirement for ATP (or a closely related molecule), whereas the proton-motive force is neither sufficient nor essential.
Adenosine Triphosphate↗
Effects of nitrogen fertilizer and weed control on nutritive quality of carrots (Daucus carota L.).
The nutritive quality of carrots, obtained from different herbicide-treated plots and under different levels of nitrogen application ranging from zero to 80 kg nitrogen/ha, was compared. There were significant differences in carotene content, T.S.S. (total soluble solids) and organoleptic characteristics under the influence of different treatments. The maximum carotene content, T.S.S. and organoleptic characteristics were observed with the application of 80 kg. nitrogen/ha and fluchloralin herbicide at 0.90 and 1.20 kg/ha.
Carbohydrates↗
Conservative management of a severely alloimmunized pregnancy: case report.
A pregnancy complicated by severe alloimmunization because of anti-E antibodies was evaluated with fetal movement counts, nonstress tests, and serial ultrasonography-amniocentesis. The successful outcome of this case suggests that such treatment may be an acceptable alternative to intrauterine transfusions for very select cases of severe alloimmunization.
Adult↗
Prevalence and significance of group B Streptococcus in a large obstetric population.
Between Jan. 1 and Dec. 31, 1985, vaginal swabs were obtained for culture for group B beta-hemolytic Streptococcus (GBS) from 3078 women admitted for labour and delivery to Regina General Hospital. Seventy-one women had positive results; thus, the colonization rate was only 2.3%. The charts of the 71 women and their 73 babies were analysed. Of the 58 babies from whom swabs were obtained, 20 had GBS at one or more sites; the transmission rate was therefore 34%. Early-onset GBS disease developed in one infant. Two infants died within the first month; however, death was not directly attributable to GBS. Higher rates of preterm delivery and of low birth weight were noted among the babies of the colonized women than among the babies of all women admitted for labour and delivery in 1985. Given the low rate of GBS disease in our centre, we suggest that emphasis be placed on GBS as a possible source of obstetric complications such as preterm labour.
Adolescent↗
Delayed appearance of Bochdalek hernia.
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Child, Preschool↗