Search PubMed⌕ Search

Biomedical subjects

P Ghosh

Publications and source records attributed to P Ghosh.

At least 325 records · Page 18Linked to original sources
PubMed1986

Primary angiosarcoma of the heart detected by two-dimensional echocardiography.

A 24-year-old woman with a history of syncope and recurrent hemopericardium was urgently hospitalized with signs of severe right-sided heart failure. Two-dimensional echocardiography demonstrated a largedechogenic mass that compressed the right ventricle. The patient was referred for emergency surgery. A large angiosarcoma originating in the right atrium was excised, and the patient was treated with chemotherapy. The role of echocardiography in the detection of cardiac tumors is discussed.

Adult↗
PubMed1985

The proteoglycans of the canine intervertebral disc.

The high-buoyant-density proteoglycans of the nucleus pulposus and annulus fibrosus of the beagle intervertebral disc have been isolated by CsCl density gradient ultracentrifugation. The sulphated proteoglycans were labelled in vivo with 35SO4, 24 h and 60 days prior to killing. The hydrodynamic size and aggregation of the 24 h, 60 day and resident (from hexuronic acid and hexosamine analysis) proteoglycan subunit populations were determined by Sepharose CL-2B chromatography in the presence or absence of excess hyaluronic acid. The hydrodynamic size of the keratan sulphate-proteoglycan core protein complexes were also determined by Sepharose CL-2B chromatography after chondroitinase ABC digestion of proteoglycans. When initially synthesised (24 h) or after 60 days, the percentage aggregation and hydrodynamic size of the proteoglycans derived from the annulus fibrosus were larger than those present in the nucleus pulposus. Hexosamine, hexuronic and protein determination of the high-buoyant-density fractions showed that the proteoglycans of the nucleus pulposus were richer in chondroitin sulphate than those in the annulus. However there was no difference in Mr of the chondroitin sulphate and keratan sulphate attached to the proteoglycans of the two disc regions, nor were differences detected by HPLC between the proportions of chondroitin 4-sulphate and chondroitin 6-sulphate present in these high-density fractions. In contrast, the low-buoyant-density (1.54 greater than p greater than 1.45) proteoglycan fractions and tissue residues remaining after 4 M GuHCl extraction were found to contain dermatan sulphate, suggesting the presence of a third proteoglycan species possibly associated with the collagen of the fibrocartilagenous matrix.

Animals↗
PubMed1985

Effects of spinal fusion on the proteoglycans of the canine intervertebral disc.

Posterior lumbar two-level spinal fusion was undertaken in 10 mature beagles. The animals were sacrificed 6 and 12 months later. Two months before sacrifice control and experimental animals received intravenously Na2(35)SO4 (1 mCi/kg). Discs encompassed by the fusion and those adjacent to it were dissected into the nucleus pulposus and annulus fibrosus (AF), which were analysed separately. Proteoglycans (PGs) were extracted with 4.0 M guanidine HCl and purified by CsCl density gradient ultracentrifugation. The hydrodynamic size and ability of the PG subunits to aggregate in the presence of hyaluronic acid were investigated by Sepharose CL-2B chromatography. The PG subunits were analysed for their galactosamine (galN), glucosamine (glcN), hexuronic acid, and protein content or were subjected to digestion with papain or chondroitin-ABC-lyase to establish the size of the chondroitin (CS) and keratan (KS) sulphate chains and the KS-PG core protein complex. Decreased ability to aggregate of PGs isolated from discs 6 and 12 months after surgery was demonstrated. While their hydrodynamic size after 6 months was generally the same or smaller than those in control tissues, the PG population present after 12 months was larger, particularly in the AF. Analysis of PG subunits from fusion discs afforded galN/glcN, galN/protein, and hexuronic acid/protein ratios that were compatible with the presence in these tissues of PGs in which the proportion of CS attached to core protein was greater than in control tissues. These studies provide the first experimental evidence that a metabolic response of discs in a fused segment may be accompanied by the biosynthesis of a new PG population whose structure is similar to that present in immature tissues.

Animals↗
PubMed1985

Polyadenylation of a human mitochondrial ribosomal RNA transcript detected by molecular cloning.

We have identified by molecular cloning a polyadenylated RNA transcript in the human leukemia cell line, K562, which is complementary to a portion of the gene-encoding mitochondrial 16S ribosomal RNA (mt 16S rRNA). The cloned portion of the transcript corresponds to positions 2191-2395 of the human mt genome. The clone represents a cDNA copy of an RNA transcript from the H strand and carries an additional poly(A) tail 21 residues long at its 3'-end. Our data provide direct evidence for polyadenylation of some mt 16S rRNA transcripts.

Base Sequence↗
PubMed1985

Synthetic inhibitors of human leukocyte elastase Part 1--Sulphated polysaccharides.

Ten dextran sulphates and six chitosan sulphates of variable Mr and extent of sulphate substitution have been examined for their ability to inhibit human leukocyte elastase (HLE). All were potent partial non-competitive inhibitors of this enzyme, highest activity being obtained with compounds of large molecular weight and maximum sulphate incorporation (Ki = 5.0 X 10(-10)M]. In all cases, the dextran sulphates were more effective inhibitors than chitosan sulphates of similar size and charge, but both classes were inactive against bovine trypsin, chymotrypsin and porcine pancreatic elastase at concentrations less than 10(-4)M. The data suggest that drug binding to HLE occurs by stereospecific electrostatic interactions at site(s) removed from the catalytic reaction centre.

Chitin↗
PubMed1985

Distribution and binding of glycosaminoglycan polysulfate to intervertebral disc, knee joint articular cartilage and meniscus.

The relative incorporation of 3H-Glycosaminoglycan polysulfate (3H-GP, Arteparon) into rabbit knee joint articular cartilage, patella cartilage, meniscus and intervertebral disc tissues was determined at 1, 2, 4 and 8 d after intramuscular administration (60 muCi/kg, 400 micrograms/kg). The distribution of the drug within these tissues was also examined autoradiographically. The highest uptake of 3H-GP occurred in the menisci and was observed to be largely localised about collagen fibres on the outer periphery of these tissues. Over the eight day period, the level present declined to approximately 50% of that present on day one. The level of drug attained in articular and patella cartilages was approximately 20-25% of that in the meniscus. It was uniformly dispersed and remained fairly constant over the eight day period. Of greatest interest was the finding for the disc, where the highest level of labelling, which occurred on day two, was comparable to the knee joint hyaline cartilages and was associated with the collagenous lamella structure of the outer annulus fibrosus. After day two, the level of drug in these areas declined, accompanied by an accumulation in the nucleus pulposus. Using an ion exchange assay technique, and gel permeation chromatography of 4M guanidine hydrochloride extracts of these connective tissues, binding of 3H-GP to proteoglycans, collagen and non-collagenous proteins, was demonstrated; the latter component representing the major drug binding species. It is suggested that localisation of the drug within these connective tissues may be beneficial in protecting their matrix components against enzymatic degradation in the pathological state.

Animals↗
PubMed1984

Polypeptide proteinase inhibitor from human articular cartilage.

A polypeptide proteinase inhibitor from human articular cartilage has been purified to homogeneity by stepwise Sephadex G-75, heparin-Sepharose and octyl-Sepharose affinity chromatography. The inhibitor is strongly cationic (pI greater than or equal to 10.5) and consists of two non-identical polypeptides associated by means of electrostatic and/or hydrophobic interactions. Amino acid analysis of the aggregate confirmed that the polypeptide was rich in basic, and hydrophobic amino acids and contained only one disulphide bridge. Sedimentation equilibrium studies showed that the aggregate had MW congruent to 7000 which could be dissociated into two polypeptides each of MW congruent to 3500. While the subunits were primarily serine proteinase inhibitors the aggregate form could also inhibit bacterial collagenase and pepsin but not thermolysin nor the cysteine proteinases, ficin or bromelain. Binding of 125I-labelled human cartilage inhibitor to heparin, keratan sulphate and proteoglycan subunit was demonstrated using gel exclusion chromatography but no interaction was detected with chondroitin 6-sulphate or hyaluronic acid. Binding of cartilage inhibitor subunits to link proteins was also shown by polyacrylamide electrophoresis. These data suggest that the human cartilage inhibitor may be localised at specific sites on the proteoglycan complex where it would be ideally placed to attenuate degradation by matrix proteinases or constitute part of an enzyme-inhibitor complex.

Amino Acids↗
PubMed1984

Microinjury to the synovial membrane may cause disaggregation of proteoglycans in rabbit knee joint articular cartilage.

Proteoglycans (PGs) isolated from articular cartilage (AC) of mature rabbits subjected to two or more consecutive intraarticular (IA) injections of sterile saline 24 h apart showed an aggregation defect in the presence of excess hyaluronic acid (HA). Although the PG contents of experimental and control cartilages were indistinguishable, a higher proportion of PGs were extractable from the 3 X IA tissues, as assessed by uronic acid analysis. Proteoglycans from experimental and control cartilages when examined by Sepharose CL-2B chromatography showed two subunit populations, the smaller (KAV = 0.70) containing more ketatan sulphate than the larger (KAV = 0.31). Cultures of AC from IA joints released more 35SO4-labelled PGs into the media over 72 h than control tissues and consisted mainly of PG degradation products although 20% could aggregate in the presence of HA. Examination of PG aggregation 2 weeks after 2 X IA or 3 X IA injections showed that the defect initiated was still present; however, cartilage of immature rabbits was not affected by the 2 X IA procedure.

Animals↗
PubMed1984

The effect of bilateral medial meniscectomy on articular cartilage of the hip joint.

Bilateral medial meniscectomy of the knee joint was undertaken in 4 mature greyhounds. Four greyhounds of similar age served as nonsurgical controls. Six months after meniscectomy, all animals were sacrificed and femoral head articular cartilage (FHC) examined for collagen, uronic acid, galactosamine, glucosamine and hyaluronic acid (HA) content. The sequential extractability of proteoglycans (PG) with non-dissociative (0.5 M GuHCl) and dissociative (0.4 M GuHCl) solvents was also investigated. The levels of collagen, uronic acid, galactosamine and glucosamine of the FHC of the meniscectomized group remained normal relative to FHC taken from the control greyhounds but the level of HA was significantly depressed (p less than 0.05). The amount of PG extracted by 0.5 M GuHCl from the FHC of the meniscectomized group was 2.5 X that extracted from control cartilage. In addition, subsequent extraction of the residues with 4.0 M GuHCl only released half the amounts of PG extracted from control FHC under the same conditions.

Animals↗
PubMed1983

Detection of protease inhibitors using substrate-containing sodium dodecyl sulfate-polyacrylamide gel electrophoresis.

A technique is described to detect the activity of protease inhibitors present in sodium dodecyl sulfate (SDS)-polyacrylamide gels (PAG) containing a copolymerized enzyme substrate. The method involved (1) incorporation of substrate (gelatin or casein) into the SDS-PAG at the time of casting; (2) electrophoresis of the protease inhibitors in the presence of SDS; (3) removal of SDS by washing the gel in 2.5% (w/v) Triton X-100; (4) incubation of the gels in a solution containing the proteolytic enzyme at 37 degrees C for 16 h; and (5) staining undigested substrate with amido black. Standard inhibitors such as bovine pancreatic trypsin inhibitor (BPTI), soybean trypsin inhibitor (SBTI), alpha 1-antitrypsin inhibitor, and a protease inhibitor derived from human articular cartilage have been examined by this method and displayed sharp inhibition bands when the gels were treated with bovine trypsin, chymotrypsin, or other enzymes. The technique cannot be used for precise quantification of protease inhibitors. However, there is a relationship between the concentration of inhibitor used and the intensity of staining. By this means, it was possible to estimate the smallest amount of inhibitor that could be detected (against a particular enzyme) under a given set of conditions. Inhibition was detected when 10 ng of SBTI or 20 ng of BPTI were applied to the gels; human alpha 1-protease inhibitor could be detected at a level of 2-3 micrograms. The technique was used to investigate the effectiveness of the human cartilage inhibitor against a variety of proteolytic enzymes, including thermolysin, Pronase, neutral protease, elastase, protease VII, pepsin, bacterial collagenase, protease IV, and papain.

Animals↗