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Biomedical subjects

P Ghosh

Publications and source records attributed to P Ghosh.

At least 217 records · Page 12Linked to original sources
PubMed1993

The role of cartilage-derived antigens, pro-coagulant activity and fibrinolysis in the pathogenesis of osteoarthritis.

Superficial fraying, splitting and fibrillation of articular cartilage as a consequence of ageing or mechanical injury is not always associated with joint pain. However, similar cartilage lesions accompanied by synovitis and engorgement of the subchondral vasculature generally is; the disorder being known as osteoarthritis (OA). In this hypothesis it is contended that the progression of early cartilage fibrillation to symptomatic OA arises as a consequence of the antigenic nature of cartilage components which when released into synovial fluid and the circulation can stimulate leukocytes (to a varying degree) to produce a number of factors some of which promote blood coagulation. While it is known that with ageing hyper-coagulation and plaque deposition is increased, the augmentation of this process by factors released by activated leukocytes is considered to exacerbate the problem. These haematological events may be particularly relevant in individuals whose leukocytes are hypersensitive to the cartilage-derived antigens, and whose fibrinolytic system is less capable of mobilizing the thrombi deposited in synovial tissues and the subchondral vascular tree.

Animals↗
PubMed1993

Distribution kinetics of inorganic mercury in the subcellular fractions of fish liver.

The present study tries to find out the kinetics of distribution of mercury in the different subcellular fractions of the liver in a freshwater perch Anabas testudineus over a period of 48 h after a single i.m. injection of [203Hg]mercuric nitrate at a dose of 4 mg/kg body weight. The fish were killed at 15 min, 2 h, 6 h and 48 h post injection. In addition the interaction of this metal with different biomolecules, viz., protein, DNA and RNA, was also investigated. Cytosol was found to be the major site of mercury accumulation. Moderate amounts of accumulation occurred in the nuclear, mitochondrial and microsomal fractions, although varying with time, while the lysosomal fraction did not reveal any spectacular retention of mercury. A significant increase in the protein content of nuclear, mitochondrial, lysosomal and cytosolic fractions was also noticed at different time periods of mercury injection. In the nuclear, microsomal and cytosolic proteins, mercury binding increased more significantly over time than the mitochondrial and lysosomal proteins. A biphasic binding pattern of mercury was seen in nuclear and mitochondrial DNA and mitochondrial and cytosolic RNA.

Animals↗
PubMed1993

The effects of intraarticular administration of hyaluronan in a model of early osteoarthritis in sheep. I. Gait analysis and radiological and morphological studies.

Using a model of early osteoarthritis (OA) induced in ovine joints by medial meniscectomy, the intraarticular effects of two hyaluronic acid (HA) preparations (AHA and DHA) were investigated. DHA was an HA preparation with an average molecular weight (MW) of approximately 2.0 x 10(6) d, and AHA had a MW of approximately 8 x 10(5) d. Animals (n = 5) were injected intraarticularly with 1 mL (10 mg/mL) of either HA preparation once a week for 5 weeks beginning 16 weeks after initiation of arthropathy. Meniscectomized, saline (1.0 mL)-injected animals (n = 5) and nonoperated sheep (n = 5) were used for controls. Force-plate analysis of gait and radiographic changes in joints were evaluated in these groups before and after intraarticular treatment. At necropsy, cartilage gross morphology, osteophyte development, and cartilage histopathology were examined. Meniscectomized joints were characterized by erosions and fissuring of cartilage of the medial compartment with areas of decreased matrix staining for proteoglycans. Osteophytes were present at the medial joint margins. Saline-treated meniscectomized animals showed reduced loading of the operated limb using the force plate. Force-plate analysis of walking animals before and after treatment with either AHA or DHA indicated some normalization of joint loading. However, osteophyte scores for meniscectomized joints injected with AHA and DHA were higher after treatment than those of the corresponding saline-treated group. Although the gross cartilage damage was lower than in saline-treated controls for both the HA-treated groups, the histological scores did not support this conclusion. Indeed, the tibial score for the DHA group was higher than for the AHA group (P < .05). These studies confirmed previous reports that meniscectomy of sheep stifle (knee) joints resulted in matrix changes similar to those described for early OA in humans. Both HA preparations appeared to improve gait, suggesting decreased lameness. Increased joint loading associated with gait improvement may account for the higher osteophyte scores in the treated groups. However, cartilage damage with DHA was found to be higher than when the lower-MW HA preparation (AHA) was used.

Animals↗
PubMed1993

The effects of intraarticular administration of hyaluronan in a model of early osteoarthritis in sheep. II. Cartilage composition and proteoglycan metabolism.

A model of early osteoarthritis (OA) induced in ovine joints by medial meniscectomy was used to study the effects of two hyaluronan (HA) preparations (AHA and DHA) on cartilage composition and proteoglycan (PG) metabolism. DHA was an HA preparation with an average molecular weight (MW) of approximately 2.0 x 10(6) d, and AHA had an MW of approximately 8.0 x 10(5) d. Both preparations were administered intraarticularly once a week for 5 weeks starting 16 weeks after meniscectomy, and animals (n = 5) were killed 5 weeks after the last injection. Meniscectomized, saline-injected (n = 5) and nonoperated (n = 5) animals were used for controls. At necropsy, 3-mm-diameter full-depth cartilage plugs were sampled under sterile conditions from specific locations on the medial and lateral femoral condyles, tibial plateaus, patella, and trochlear groove. The cartilage plugs were cultured in Hams-F12 medium supplemented with 10% fetal calf serum for 24 hours, then for a further 48 hours in the presence of H2(35)SO4 to determine the biosynthesis of PGs. The percentage of 35S-PGs and sulfated glycosaminoglycans released into the media was also ascertained. The cartilage adjacent to the plugs was analyzed for collagen and proteoglycan content and differential extractability with guanidine hydrochloride (GuHCl) solutions. The extractability of PGs with 0.4 mol/L GuHCl (nondissociative conditions) was lower from the medial femoral cartilages of the DHA-treated group than from the corresponding saline-treated group. In contrast, the release of 35S-PGs from the tibial cartilages of the DHA-treated animals was higher than in the saline-treated group. The biosynthesis of 35S-PGs, determined in vitro, for cartilage derived from the medial compartment was generally lower than for the lateral regions of the meniscectomized joints. The biosynthetic activity was further reduced in joints injected with the two HA preparations, but DHA reduced 35SO4 incorporation into PGs more than AHA. It was concluded that reduced biosynthesis of 35S-PGs and secretion into media was a consequence of increased loading of joints in the HA-treated animals rather than a direct effect of these preparations on chondrocyte metabolism.

Animals↗
PubMed1993

Effects of intraarticular hyaluronan on matrix changes induced in the lateral meniscus by total medial meniscectomy and exercise.

Total medial meniscectomy was performed in 12 adult merino sheep. Immediately after surgery, 8 animals received high-molecular-weight hyaluronan (HA) (1 mL, 10 mg/mL) and 4 were given sterile saline (1 mL) intraarticularly. Injections were given for 5 more weeks. In week 3 an exercise program, consisting of walking 24 km/wk, was initiated. This program was continued until the animals were killed at week 26 postmeniscectomy. At necropsy the lateral menisci were removed and divided into three concentric zones--inner, middle, and outer. Powdered aliquots of tissues from each zone were analyzed for collagen and hexuronate contents using colormetric methods. The glycosaminoglycans (GAGs)--chondroitin-O-sulfate (C-O-S), chondroitin-4-sulfate (C-4-S), chondroitin-6-sulfate (C-6-S), and dermatan sulfate (DS)--were determined using a high-performance liquid chromatography method. The lateral menisci from the joints of animals injected with HA showed higher hexuronate and GAG levels than those of controls. This increase was mainly due to C-6-S, which had highest levels in the inner and middle meniscal zones. In addition, dermatan sulfate levels increased significantly in the middle and outer zones of the lateral menisci compared with the same zones of the meniscus from the saline-treated group. Collagen and C-O-S levels were not statistically different from those of controls. These data suggest that intraarticular administration of high-molecular-weight HA immediately after open total medial meniscectomy may help preserve the proteoglycans in the lateral meniscus remaining in the joint.

Animals↗
PubMed1993

Moderate exercise exacerbates the osteoarthritic lesions produced in cartilage by meniscectomy: a morphological study.

Unilateral medial meniscectomy was performed on two groups of sheep. At 1 week post-operatively, one group (N = 5) underwent a regimen of moderate walking exercise (24 km/week), while the other group (N = 5) received no exercise. Two groups (N = 6 and 8) of unoperated sheep were used as exercised and unexercised controls for the respective meniscectomized groups. Six months post-surgery all groups were sacrificed and their knee joints were examined macroscopically using established scoring systems. In both groups, meniscectomy induced cartilage and bone changes typical of early hypertrophic osteoarthritis. However, meniscectomized animals subjected to the exercise program developed more severe cartilage lesions and osteophytes than their unexercised counterparts. While the cell density in femoral cartilage of the meniscectomized and exercised group was similar to controls, that of the meniscectomized but unexercised animals was higher. We conclude form these data that in this animal model exercise exacerbated the lesions induced in articular cartilage by meniscectomy.

Animals↗
PubMed1993

Effects of chronic ethanol on enzymes regulating sialylation and desialylation of transferrin in rats.

Transferrin is N-glycosylated glycoprotein and plays an important role in iron transport from sites of absorption and storage to sites of utilization. Chronic ethanol alters the normal microheterogeneity pattern of transferrin as a consequence of changes in the sialic acid content. However the underlying basis of this change in sialic acid contents of transferrin in alcohol abuse remains unclear. We have undertaken this study in order to investigate the effects of chronic ethanol in rats with respect to the hepatic rate of (i) transferrin synthesis based on labeled leucine incorporation, (ii) the incorporation of labeled N-acetyl mannosamine (NAM) into sialic acid residues of transferrin, and (iii) roles of specific sialyltransferase and sialidase at hepatic subcellular level. The results showed no significant difference in the incorporation of labeled leucine into transferrin at all levels between the control and ethanol group, whereas the incorporation of NAM into transferrin was significantly decreased by 84% (p < 0.001) both at the whole cell and Golgi level. Thus, the incorporation of labeled NAM relative to the incorporation of labeled leucine into hepatic transferrin was significantly decreased by 86% (p < 0.001) in chronic ethanol-treated animals as compared with the controls both at the whole cell golgi levels. These data are further supported by our finding of concomitant decrease in the activity of beta-galactoside alpha 2,6-sialyltransferase by 58% (p < 0.01) in ethanol-treated rats as compared with control animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Alcoholism↗
PubMed1993

A comparison of effect of temperature on phosphorus metabolites, pH and Mg2+ in human and ground squirrel red cells.

1. 31P NMR spectra were obtained at temperatures ranging from 2 to 30 degrees C from freshly drawn human (cold-sensitive) and ground squirrel (cold-tolerant) red cells. The concentration of ATP was also determined by luciferin-luciferase assay over the same temperature range. 2. The concentration of ATP as determined by NMR or by the luciferin-luciferase assay did not change with temperature in either species. The absolute concentration of ATP in human cells determined by NMR was not significantly different from the total ATP determined enzymatically. 3. The concentration of 2,3-diphosphoglycerate was higher and that of pyridine nucleotides lower in human than in ground squirrel red cells. This species difference was independent of temperature. 4. Intracellular pH, as determined from the positions of the NMR peaks of 2- and 3-phosphates of diphosphoglycerate, became more alkaline as the temperature was lowered. 5. Free intracellular magnesium, determined from the difference in the positions of the peaks for alpha- and beta-phosphorus of ATP, increased in the ground squirrel red cells and decreased in the human red cells with cooling from 30 to 2 degrees C. Total magnesium, as determined by atomic emission spectroscopy, did not change with temperature in red cells of either species. 6. The intensities of all phosphorus metabolite signals from the ground squirrel cells increased with decreasing temperature, while those from the human cells were unaffected. Since chemical shift anisotropy in the presence of magnesium is a powerful spin-lattice relaxation mechanism for phosphates, this is additional evidence for the temperature dependence of free magnesium concentration in the ground squirrel cells. 7. We conclude that there is no difference in phosphorus metabolites or intracellular pH which could account for the differential cold sensitivity in human and ground squirrel red cells. We suggest that, in the cold-tolerant red cells from the ground squirrel, magnesium is released from binding sites as the temperature is lowered. The change in free intracellular Mg2+ may account at least in part for the unusually low temperature sensitivity of the Na(+)-K+ pump in the red cells of this species.

2,3-Diphosphoglycerate↗
PubMed1993

Time dependent distribution of [203Hg] mercuric nitrate in the subcellular fractions of rat and fish liver.

Cytotoxicity of inorganic mercury to the liver of two species, Anabas testudineus and Sprague Dawley male rat was evaluated. Distribution kinetics of this metal in the different hepatic subcellular fractions were followed for 48 h after a single injection of [203Hg] mercuric nitrate at a dose of 4mg/kg b.w. Interaction of this metal with protein, DNA and RNA was also studied. In rat, nuclear and lysosomal fractions showed a significant increase in the protein content, while in fish, the amount of protein increased in all fractions except microsome. Comparatively more mercury was bound to protein in fish during the later phase of treatment. Retention of mercury in nuclear DNA of rat gradually declined from 15 min to 48 h of treatment, while, mitochondrial DNA binding to mercury increased from 15 min to 2 h of post injection and then declined in the later phase of the experiment. Such a biphasic binding pattern of mercury was shown by both the nuclear and mitochondrial DNA of the fish. The nuclear RNA of rat and mitochondrial and cytosolic RNA of both test species also showed a biphasic pattern of mercury binding, however, with a higher rate of binding in fish at the later phase of the experiment. The present study thus highlights that (a) mercury follows a definite distribution pattern in the subcellular fractions of the liver in both animal species, (b) cytosol is the major site of mercury accumulation.

Animals↗
PubMed1992

The chondroprotective drugs, Arteparon and sodium pentosan polysulphate, increase collagenase activity and inhibit stromelysin activity in vitro.

The effects of the chondroprotective drugs, sodium pentosan polysulphate (SP54) and Arteparon (glycosaminoglycan polysulphate), on the in vitro activities of the purified matrix metalloproteinases interstitial collagenase (matrix metalloproteinase 1, MMP1) and stromelysin (MMP3) were examined. Both drugs produced concentration-dependent enhancement of the degradation of type I collagen fibrils by purified human fibroblast collagenase and rat tumour collagenase. Rat collagenase activity was increased by drug concentrations above 0.5 microgram/mL, whereas human collagenase activity was only increased by higher drug concentrations, above 5 micrograms/mL. The concentration dependence of the increase in rat collagenase activity was similar for both drugs, with a maximal 3-fold increase at 50 micrograms/mL. In contrast, human collagenase activity was increased to a greater extent by SP 54 compared to Arteparon, with maximal increases at 5000 micrograms/mL of 6-fold and 2-4-fold, respectively. Both drugs produced concentration-dependent inhibition of the proteoglycan-degrading activity of both human fibroblast stromelysin and rat tumour stromelysin. Rat and human stromelysin activities were inhibited at drug concentrations above 0.005 microgram/mL, with a similar concentration dependence for both drugs. Fifty percent inhibition of rat stromelysin was produced by concentrations of each drug in the 0.5-5 microgram/mL range. The pattern of inhibition of human stromelysin was similar, except that drug concentrations in the 500-5000 micrograms/mL range produced 50% inhibition. The possible modes of action for these drug effects and their possible pharmacological significance are discussed.

Animals↗
PubMed1992

Liposome shrinkage and swelling under osmotic-diffusional stress: evaluation of kinetic parameters from spectrophotometric measurements.

Analyses of spectrophotometric measurements of shrinkage and swelling of liposomes under osmotic-diffusional stress tacitly assume an 'empirical' inverse relationship between the absorbance (A) and the liposomal volume (v). In this paper, we have proposed an alternate more explicit relationship: A = EcL e - alpha Lv/1-Lv where L is liposomal concentration, Ec the extinction coefficient and alpha a dimensionless parameter. The exponential term, in essence, defines the partitioning of aqueous volume into intra- and extra-liposomal compartments. Experimental data obtained with glycerol as model compound are used to test the validity and internal consistency of the proposed formalism.

Kinetics↗
PubMed1992

Development of an avidin-biotin competitive inhibition assay and validation of its use for the quantitation of human intervertebral disc serine proteinase inhibitory proteins.

A simple convenient method has been developed for the quantitation of serine proteinase inhibitors (SPIs) in tissue extracts. The method is based on the competitive binding to trypsin and chymotrypsin immobilized using glutaraldehyde on 96-well microtiter plate wells of native SPIs and a biotinylated secretory proteinase inhibitor (SLPI) standard. The bound SLPI standard was visualized using an avidin-alkaline phosphatase conjugate and inhibition curves were determined using absorbancy measurements at 405 nm. The standard assay had a range between 0.02 and 1 microgram SLPI/well and a lower detection limit of 20 ng SLPI/well; an improved microassay had a detection limit of 2 ng SLPI/well. Only active free inhibitor was detected in the assay since denatured and/or enzyme-inhibitor complexes did not bind to the plates. A range of SPI species was demonstrable in human bronchial mucus and intervertebral disc SPI samples using this technique. Quantitation of SPI levels in a number of intervertebral disc samples indicated that the SPIs were depleted in degenerate discs compared to nondegenerate discs (P less than 0.05, n = 12). Since the immobilized trypsin and chymotrypsin microplates used in this assay may be prepared in advance (and are stable at 4 degrees C for at least 1 month) the remaining two steps of the assay (the inhibition step and visualization) may be completed in 2-3 h; thus the assay is simple, convenient, and fast. All reagents (other than the biotinylated SLPI standard) are readily available commercially, and in principle the assay could be adapted to other systems provided defined biotinylated standards were available.

Avidin↗
PubMed1992

The c-rel protooncogene product c-Rel but not NF-kappa B binds to the intronic region of the human interferon-gamma gene at a site related to an interferon-stimulable response element.

Interferon-gamma (IFN-gamma) is an important immunoregulatory protein that is expressed usually only in large granular lymphocytes and T cells. The gene encoding IFN-gamma was previously found to contain an intronic enhancer element that was not tissue-specific in its activity, despite the restricted expression of the intact IFN-gamma-encoding gene. Using nuclear extracts from the human T-cell line Jurkat, we have now identified two protein-binding regions in this intronic enhancer element. One of the protected regions has strong partial identify to the NF-kappa B site present in the promoter region of the human interleukin 2-encoding gene. Based on this observation and recent reports of the interaction of the c-rel protooncogene product (c-Rel) with NF-kappa B sites, we determined whether c-Rel could interact with the intronic enhancer element in the human IFN-gamma genomic DNA. Most surprisingly, gel-shift analysis, using c-Rel expressed in Escherichia coli established that c-Rel binds specifically to the IFN-gamma intronic DNA but not to the interleukin 2-like NF-kappa B site. Additional studies with antibodies prepared against c-Rel peptides verified specificity of the interaction of c-Rel with this binding site. In addition, using an affinity-purified p50 subunit of the NF-kappa B complex, we observed that the p50 protein did not bind to this additional c-Rel-binding site. Furthermore, nucleotide sequence analysis of this DNA region revealed a strong similarity of the additional c-Rel-binding site to a previously identified IFN-stimulable response element. These data show that c-Rel can interact with DNA regions distinct from that recognized by NF-kappa B and may, in fact, be involved in transcriptional regulation of the IFN-stimulable genes via the IFN-stimulable response element.

Base Sequence↗
PubMed1992

A longitudinal study of the matrix changes induced in the intervertebral disc by surgical damage to the annulus fibrosus.

A 5 x 5-mm anterolateral incision was made in the annulus fibrosus (AF) of lumbar discs of 16 sheep; four animals of similar age not operated on were used as controls. The experimental animals were sacrificed 2, 4, 6, 8, 12, and 18 months postoperatively (PO), and the incised and adjacent lumbar discs were collected. Discs were dissected into four zones: AF (zones 1 and 2) and nucleus pulposus (NP) (zones 3 and 4) corresponding to the half of the AF in which the cut was made and its opposite half, and the complementary halves of the NP. Each zone was analyzed for moisture, proteoglycan (PG), collagen, and noncollagenous protein (NCP) content. The PG extractability, aggregation, and hydrodynamic size were also examined. The NP of injured discs showed a significant loss of PGs and collagen 8 months PO, but NCP levels increased. In the incised discs, PG aggregation initially declined but recovered to within control values 6-8 months PO. The NP of discs adjacent to the incised disc also showed time-dependent changes in matrix components that included loss of collagen and PG; however, the AF matrix remained essentially uneffected. Double immunodiffusion studies indicated that a sizeable proportion of the NCPs present in the injured discs (but not the adjacent lumbar discs) were derived from serum.

Animals↗