Search PubMed⌕ Search

Biomedical subjects

P Ghosh

Publications and source records attributed to P Ghosh.

At least 253 records · Page 14Linked to original sources
PubMed1991

The influence of scoliosis and ageing on proteoglycan heterogeneity in the human intervertebral disc.

Proteoglycans (PGs) purified from 19-year-old male (19M), 53-year-old female (53F), and 15-16-year-old adolescent idiopathic scoliotic (AIS) disc tissues were characterised by their aggregation properties with hyaluronic acid (HA), glycosaminoglycan (GAG), and amino acid composition, electrophoretic mobilities by composite agarose polyacrylamide gel electrophoresis (CAPGE), and hydrodynamic size by Sepharose CL2B gel permeation chromatography. Proteoglycan levels were similar in the AIS and 53F discs, but considerably higher levels were found in the 19M discs. Proteoglycan populations assessed by the aforementioned criteria demonstrated a similar level of heterogeneity in the AIS and 53F discs but this differed with the 19M sample. Two small Mr, low buoyant density PG species were particularly prominent in AIS and 53F discs: these were similar to two nonaggregating PG species formerly reported by di Fabio et al.; however, the corresponding PG species in 19M discs were of somewhat different composition. Collectively, these data suggest similar processing of PGs in the AIS and 53F discs. Furthermore, the pattern of normal age changes in the PGs from AIS discs appears to be disturbed, most likely arising as a consequence of the abnormal biomechanical forces intrinsic to the deformity.

Adolescent↗
PubMed1991

Saturation effects in phosphorus-31 magnetic resonance spectra of the human liver.

Phosphorus-31 liver spectra were recorded from 6 controls and 12 patients with liver disease using TR values of 0.5 and 5 s and a pulse angle of 45 degrees. One of the control subjects was also examined at seven TR values ranging from 0.5 to 20 s. Spectra from one additional patient were collected at TRs of 0.5, 1, and 2 s only. There was a significant increase in the mean ratio of peak areas phosphomonoesters (PME)/beta-ATP in 9 of the 13 patients and a decrease in phosphodiesters (PDE)/beta-ATP in 3 of the patients, compared with controls, at the longer TR values. The saturation factors for PME and PDE were greater than those for Pi and beta-ATP, and spectral abnormalities in disease were often more evident as the TR value was increased from 0.5 to 5 s. Acquisition parameters need to be chosen with a knowledge of the impact that saturation effects have on metabolite quantification and spectral contrast.

Adenosine Triphosphate↗
PubMed1991

Inhibition of human fetal brain acetylcholinesterase: marker effect of neurotoxicity.

Human fetal brains were obtained after medical termination of pregnancy at 8-10 wk from informed patients. A definite regionalization of AChE was found in the brain of the fetus, with cerebellum recording the highest and cerebral hemisphere the lowest activity. Optimum conditions for the cerebellar AChE activity were determined with respect to molarity of the buffer, pH, temperature, and concentrations of substrate (acetylthiocholine iodide), activators (NaCl, MgCl2), and thiol indicator (dithiobisnitrobenzoic acid). In vitro inhibition of cerebellar AChE with two commercial pesticides, Metacid-50 (O,O-dimethyl p-nitrophenyl phosphorothioate) and carbaryl (N-methyl naphthyl-1-carbamate), were compared with pure anticholinesterase agents, diisopropylfluorophosphate (DFP) and physostigmine (eserine). In general, organophosphates are more neurotoxic than carbamate compounds, as evidenced by higher degree of AChE inhibition by DFP and Metacid-50 as compared to eserine and carbaryl. Assays were also done with psychotropic drugs by employing the procedure of in vitro AChE inhibition kinetics, and it was found that psychotropic drugs are less potent than organophosphate and carbamate compounds. Results indicate that pure and commercial organophosphates and carbamates and psychotropic drugs are all able to significantly alter the AChE activity. Thus exposure of the mother to these environmental toxicants may adversely affect the fetal neural functions.

Acetylcholinesterase↗
PubMed1991

Changing pattern of peptic ulcer in India. An endoscopic study of 1,188 ulcer patients.

Earlier studies have described a profile of peptic ulcer different in developing and developed countries. In a prospective endoscopic study in India over 5 years and 8 months involving 5,948 patients with upper gastrointestinal symptoms, we detected peptic ulcers in 1,188. There were 920 patients with duodenal ulcer (DU), 185 with gastric ulcer (GU), and 83 with combinations of the two. The male to female ratio was 4.2:1. About half the ulcers were in patients age greater than or equal to 40 years. Of the 223 (18.7%) patients with peptic ulcer complications, gastrointestinal bleeding was the most common (12.7%) and gastric outlet obstruction was less common (6.2%). Endoscopic evidence of duodenal bulb deformity was seen in 74.4% of DU patients. A comparison of these results with data from previous Indian studies suggests a changing trend of peptic ulcer with respect to age and sex distribution, the ratio between DU and GU, and complications of peptic ulcer. The profile of peptic ulcer in north India today is similar to that seen in Western countries four to five decades ago. We discuss possible factors responsible for this change.

Adult↗
PubMed1991

Effect of chronic ethanol on apolipoprotein (Apo) E synthesis and glycosylation in rats.

We have previously shown in rats that chronic ethanol feeding significantly inhibits the incorporation of labeled leucine into Apo E secreted into the liver perfusate (p less than 0.01). Fish oil has been shown to counteract many of the adverse effects of ethanol. In order to explore whether this inhibitory effect of ethanol was due to the decreased synthesis and/or defective glycosylation of this glycoprotein, we have determined the effects of chronic ethanol and fish oil on the synthesis and glycosylation of Apo E in vivo. Four groups of male Wistar rats were pair-fed the following liquid diets for 8 weeks; (1) Ethanol Regular Fat, (2) Control Regular Fat, (3) Ethanol Fish Oil, and (4) Control Fish Oil. At the end, the rats were intraportally injected with a single dose of [U-14C]leucine (0.2 microCi/g body weight) and/or [2-3H]mannose (1 microCi/g body weight) and killed after 30 min. The incorporation of the labeled precursors into the immunoprecipitable Apo E was measured in the liver and its microsomal and Golgi fractions. The results showed marked decreases in mannose incorporation into total glycoproteins and specifically of Apo E in whole liver, microsomal, and Golgi fractions under ethanol treatment. In contrast, the leucine incorporation into liver Apo E increased 11% (p less than 0.048) by ethanol treatment. As a result, the [3H]mannose/[14C] leucine incorporation ratio also decreased 41% to 47% at the whole liver, microsomal, and Golgi fractions indicating a marked inhibition in glycosylation of Apo E in the ethanol group.(ABSTRACT TRUNCATED AT 250 WORDS)

Alcoholism↗
PubMed1991

Effects of hydrogen peroxide on the metabolism of human rheumatoid and osteoarthritic synovial fibroblasts in vitro.

The effects of hydrogen peroxide (H2O2) on the metabolism of cultured human synovial fibroblasts derived from joints of four patients with rheumatoid arthritis and three with osteoarthritis have been investigated. The exposure of rheumatoid cell cultures to this oxygen derived species at sublethal concentrations (1-100 mumol/l) induced a dose related inhibition of both hyaluronic acid (HA) and DNA synthesis. In contrast, in osteoarthritic cell lines a biphasic response was shown. At low concentrations of H2O2 (less than 10 mumol/l) a stimulatory effect on HA synthesis was noted, whereas in the presence of higher concentrations (greater than 10 mumol/l) a significant inhibition of synthesis occurred. These deleterious effects of H2O2 were partially reduced by the addition of catalase to the culture media. The finding that both HA and DNA synthesis were inhibited at concentrations of H2O2 less than those which caused loss of cell integrity (greater than 200 mumol/l) suggests oxidation of intracellular components, such as glyceraldehyde-3-phosphate dehydrogenase, and subsequent depletion of ATP concentrations.

Arthritis, Rheumatoid↗
PubMed1991

Recent advances in animal models for evaluating chondroprotective drugs.

While a variety of animal models have been described to evaluate the effects of antiarthritic and chondroprotective drugs on cartilage metabolism, most cannot be said to truly reproduce the temporal changes that occur in human osteoarthritis (OA). Total meniscectomy is a common orthopedic procedure in humans and frequently leads to OA in later years. We investigated the effects of unilateral medial meniscectomy in sheep knee joints subjected to moderate regular exercise. Morphological and biochemical studies of joint cartilage after 6 months revealed slowly progressive changes similar to those seen in early OA, characterized by cartilage fibrillation, chondrocyte hypertrophy, matrix proliferation and marginal osteophyte formation. The proteoglycans synthesized contained more chondroitin-4-sulphate than chondroitin-6-sulfate.

Animals↗
PubMed1990

A new sandwich-ELISA method for the determination of keratan sulphate peptides in biological fluids employing a monoclonal antibody and labelled avidin biotin technique.

A new sandwich-ELISA for the determination of keratan sulphate peptides in biological fluids is described. The technique involves binding a commercially available monoclonal antibody against keratan sulphate to microtitre plates, adding the unknown keratan sulphate antigen then interacting the keratan sulphate-antibody complex with a biotin-monoclonal antibody conjugate which was also specific for keratan sulphate peptides. Alkaline phosphatase conjugated streptravidin was then added and the amount which bound to the biotin was determined by measuring the release of chromogen from an added chromogenic substrate. Using this assay, keratan sulphate peptides in biological fluids within the range 10-1000 ng/ml could be quantitated. This method was found to be more sensitive than presently used techniques. The intra- and inter-assay coefficients of variation were 11% and 13%, respectively.

Adult↗
PubMed1990

L-pipecolic acid metabolism in human liver: L-alpha-aminoadipate delta-semialdehyde oxidoreductase.

A soluble enzyme that catalyzes the oxidation of L-alpha-aminoadipate delta-semialdehyde to L-alpha-aminoadipic acid in the presence of NAD+ has been isolated and characterized from human liver. This enzyme L-alpha-aminoadipic delta-semialdehyde oxidoreductase has been found to be localized in the cytosol using subcellular fractionation and marker enzyme assays. The reaction product of this enzyme has been identified as L-alpha-aminoadipic acid by use of an amino acid analyzer and thin layer chromatography. The enzymatic reaction was irreversible and has a pH optimum of 8. The enzyme was stimulated by Mg2+, Cu2+ and Mn2+, and has a requirement of free -SH groups. The Km and Vmax values for its substrate L-alpha-aminoadipate delta-semialdehyde were shown to be 181 microM and 71.4 pmol.min-1.mg-1, respectively, and for its coenzyme NAD+ to be 454 microM and 142.9 pmol.min-1.mg-1, respectively. The characteristics of the oxidoreductase obtained from the human liver and Pseudomonas putida were compared.

2-Aminoadipic Acid↗
PubMed1990

A monoclonal antibody that recognizes 2,3-, 2,6-, and 4,6-disulphate ester ring substitution in pyranose-containing polysaccharides. Its production, characterization and application for the quantitation of pentosan polysulphate, dextran sulphate, glycosaminoglycan polysulphate and chondroitin sulphate E.

A method is described for the preparation of a monoclonal antibody (MAb) which binds specifically to polysaccharides which contain 2,3-, 2,6- and 4,6-disulphate ester pyranose ring substitution. Such molecules include the semisynthetic heparinoids, pentosan polysulphate (PPS), dextran sulphate (DS) and glycosaminoglycan polysulphates (GAGPS), as well as the naturally occurring polysulphated polysaccharides, chondroitin sulphate E, and the 2,6-disulphated galactoses of carrageenans. The antibody (MAb 5-B-10) did not significantly cross-react with other sulphated polysaccharides such as heparin, heparan sulphate, the chondroitin sulphates, A, B, C or D, or keratan sulphate. No cross-reactivity was found with non-sulphated polysaccharides or polyanions including hyaluronic acid, xylan, or DNA. MAb 5-B-10 was characterized as IgM and kappa light chains, and was to develop an amplified enzyme-linked immunosorbent inhibition assay (ELISIA) to detect and quantitate some of the polysulphated polysaccharides in biological fluids. Using this assay, the lower limits of detection of these compounds in serum were in the order of 50 ng/ml; however 50% inhibition was obtained between 200-500 ng/ml. The intra- and inter-assay coefficients of variation for PPS were 4.2 +/- 2.8 and 16.7 +/- 13.8% respectively. The MAb 5-B-10 and the ELISIA were used to determine the levels of PPS in plasma of three healthy non-fasted volunteers for up to 120 min post-intravenous infusion (1.0 mg/kg). The results obtained compared favourably with kinetic data reported by others using a competitive binding assay method for this drug.

Animals↗
PubMed1990

Low molecular weight serine proteinase inhibitors of human articular cartilage. Isolation, characterization, and biosynthesis.

The major low molecular weight serine proteinase inhibitor of human articular cartilage was purified to homogeneity as determined by single-peak elution with 4 high resolution techniques. The purified protein was found to be a potent inhibitor of human leukocyte elastase and cathepsin G, as well as the native serine proteinases derived from human articular cartilage and intervertebral disc. The inhibitor and lysozymes were synthesized by human articular cartilage in vitro. These properties and the ability of this cationic inhibitor to bind to cartilage matrix components suggest a possible role in the modulation of matrix catabolism in normal and pathologic states.

Amino Acids↗
PubMed1990

Central diplacusis.

Although diplacusis is usually indicative of cochlear pathology, to our knowledge causes in the central nervous system ("central diplacusis") have not been mentioned in the available literature. A case of central diplacusis involving a lesion in the posterior thalamus is now reported that resulted in diplacusis binauralis. A neuro-audiological explanation is offered to explain this phenomenon. Presumably, a lesion at the geniculate-collicular level, where pain and tactile impulses are interrelated with auditory, visual and olfactory ones, leads to the phenomenon perceived.

Auditory Perceptual Disorders↗
PubMed1990

A method for the quantitation of hyaluronan (hyaluronic acid) in biological fluids using a labeled avidin-biotin technique.

An improved method for the detection and quantitation of hyaluronan (hyaluronic acid) (HA) in biological fluids is described. The principle on which the method is based is that HA binds strongly to a biotinylated HA-binding protein (B-HABP) which was prepared from cartilage proteoglycans. HA was immobilized on polyvinyl chloride plates which had been precoated with poly-L-lysine. The unknown sample or HA standards together with excess B-HABP are then added. The B-HABP that binds to the immobilized HA is then incubated with the enzyme-conjugated avidin (e.g., alkaline phosphatase), and the color which develops on addition of enzyme substrate (e.g., p-nitrophenyl phosphate) is determined by light absorption using a microtitration plate reader. The assay is not only convenient and reliable but is capable of measuring HA in solution at the picogram level. The assay was used to determine HA levels in human sera and synovial fluid taken from volunteers and patients with rheumatoid arthritis and osteoarthritis.

Avidin↗