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Biomedical subjects

R Bhatnagar

Publications and source records attributed to R Bhatnagar.

At least 91 records · Page 5Linked to original sources
PubMed1986

Adiaspiromycosis in striped skunks in Alberta, Canada.

Pulmonary adiaspiromycosis was diagnosed in seven of 25 striped skunks (Mephitis mephitis) in east-central Alberta. The infection varied from mild, where only microscopic lesions were seen, to severe, where gross lesions of grayish-white nodules were observed in the lung parenchyma. Mild lesions were restricted to the lung, while severe lesions extended to the tracheobronchial and mediastinal lymph nodes. Histologically, the lesions were characterized by a centrally located fungal spherule, surrounded by granulomatous inflammation. The morphology of the fungal spherules was consistent with that of Emmonsia crescens. By electron microscopy, the fungal cells had an outer thick fibrillar wall and an inner cytoplasm filled with large lipid vacuoles with relatively few mitochondria, ribosomes or glycogen inclusions. The absence of endosporulation and budding suggested that each fungal cell in the lung represented a separate inhaled spore. Infection was by inhalation, nevertheless adiaspores may disseminate to the regional lymph nodes.

Animals↗
PubMed1986

Interleukin-1 inhibits the synthesis of collagen by fibroblasts.

Human dermal fibroblasts, exposed to human or porcine Interleukin-1, responded by an inhibition of collagen synthesis in a dose dependent manner. Incubation with Il-1 for more than 8 h was required to see an appreciable effect. The phenomenon was not dependent on the presence of serum in the culture medium. Since a stimulation of prostaglandin E2 secretion was also observed in presence of Il-1, we investigated the eventual role of arachidonic acid metabolites in the phenomenon. Inhibitors interfering with arachidonate metabolism, namely indomethacin, acetyl salicylic acid, BW 755 C and NDGA had no influence on the inhibition of collagen synthesis caused by Il-1. These data suggest that both cyclooxygenase and lipoxygenase derived metabolites of arachidonic acid are unlikely to play a role in the mechanism.

Animals↗
PubMed1986

Kinetics of reabsorption of nutrients in renal brush border membrane vesicles from rats with experimental ascending pyelonephritis.

The uptake of nutrients was investigated in the renal cortical brush border membrane (BBM) vesicles at different stages of ascending pyelonephritis. There was significant difference (p less than 0.05) in the uptake of D-glucose, L-alanine, L-aspartate, L-lysine and L-proline 3 days postinfection and onwards in both right unobstructed and left obstructed experimental kidneys as compared to the sham operated control. The uptake of D-glucose, L-lysine and L-proline was found to be significantly decreased (p less than 0.05) during the course of infection. While uptake of L-alanine and L-aspartate increased (p less than 0.05) in early stages and decreased (p less than 0.05) in later stages of infection. The differential effect was attributed to the compensatory measure and different kinds of transport systems for different types of amino acids.

Amino Acids↗
PubMed1985

Pyelonephritis alters the reabsorption of nutrients and brush border membrane enzymes of rat kidney.

The uptake of nutrients and activities of membrane enzymes in the kidney were investigated using renal brush border membrane (BBM) vesicles in acute pyelonephritis in rats. A significant decrease (P less than 0.001) in the uptake of D-glucose and L-phenylalanine was observed in both the unobstructed right and obstructed left kidney, while there was a significant increase (P less than 0.001) in the uptake of L-alanine in the left kidney of pyelonephritic rats, demonstrating disturbances in the reabsorption of the glucose and aminoacids in the kidneys. Vmax of alkaline phosphatase, leucine-amino-peptidase and maltase was found to be decreased in the left kidney, suggesting that there was a reduction in the active enzyme molecule number. Km of alkaline phosphatase and leucine-aminopeptidase remained unchanged, while km of maltase decreased in both the right and left kidneys. An increase in the Vmax of alkaline phosphatase and leucine-aminopeptidase and substrate affinity of the maltase in the right kidney demonstrated a compensatory phenomenon for the malfunctioning of the left kidney. This is the first report demonstrating alterations in reabsorption of nutrients and BBM enzymes in experimental pyelonephritis.

Absorption↗
PubMed1984

Characterization and metabolism of cyclic guanosine 3'5'-monophosphate in Mycobacterium smegmatis.

Cyclic guanosine 3'5'-monophosphate was isolated and purified from Mycobacterium smegmatis TMC 1515 using ion exchange chromatography. It was characterized by thin layer chromatography and radioimmunoassay. Guanylate cyclase and cGMP phosphodiesterase were detected in the cytosolic and particulate (37,000 X g pellet) fractions respectively. On the basis of our observations, cGMP appears to play a dual role (i) at the time of induction of cell proliferation and (ii) protects the bacteria against unfavourable surroundings during stationary phase of the growth. This is the first report demonstrating presence of cGMP, guanylate cyclase and cGMP phosphodiesterase in mycobacteria.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed1984

Continuous extraction of urinary anthracycline antitumor antibiotics with the horizontal flow-through coil planet centrifuge.

Extraction of doxorubicin (adriamycin) and daunorubicin and their metabolites from human urine was attempted utilizing the horizontal flow-through coil planet centrifuge. Partition coefficients of the drugs for various combinations of non-aqueous phases and aqueous salt solutions were determined. Optimal coefficients for adriamycin and daunorubicin were achieved with n-butanol-0.3 M disodium hydrogen phosphate. Extraction efficiencies of the drugs from human urine comparable to those obtained by standard resin column techniques could be realized by employing the n-butanol-urine (containing 0.3 M disodium hydrogen phosphate) system in the coil planet centrifuge, at flow-rates of 500-600 ml/h, and at 650 rpm revolutional speed. Small quantities of drugs and metabolites could be continuously concentrated into small volumes of the n-butanol phase from large volumes of salted urine. The versatility of the technique was demonstrated by its application to extraction of aclacinomycin A, a novel anthracycline antitumor agent, and its metabolites from human urine.

1-Butanol↗
PubMed1984

Structure activity relationships of resorcinol substituted ring systems.

Dopamine receptor agonist activity was evaluated using resorcinol derivatives of the following ring systems: dopamine, aminotetralin, indan, benzocycloheptane, octahydrobenzo(f)quinoline and octahydrobenzo[g]quinoline. The compounds were evaluated for biological activity using in vitro binding assays, anesthetized cat blood pressure and heart rate, cat cardioaccelerator nerve preparation and rotations of rats with unilateral denervation of the caudate nucleus. Resorcinol substitutions were chosen because one hydroxyl group corresponded to the alpha-conformer of dopamine and the second hydroxyl group corresponded to the beta-conformer of dopamine. Dopamine receptor activity was found primarily with derivatives of aminotetralin and octahydrobenzo[f]quinoline while the other ring systems yielded compounds which were quite inactive. The active resorcinol derivatives were found in the same ring systems where catechol substitution was active in ring positions corresponding to either the alpha- or beta-conformer of dopamine. Likewise in those ring systems where catechol substitution corresponding to the beta-conformer of dopamine were quite inactive, resorcinol substitution in these series was not favorable for activity. The ring systems requirements for alpha- and beta-adrenoceptor agonist activity did not follow the same structural pattern as found for dopamine receptor agonist activity.

Animals↗
PubMed1984

TL-350, an ergoline derivative with dopamine receptor agonist properties.

Intravenous and intraduodenal injection of a new ergoline derivative, TL-350, produced dose-dependent inhibition of heart rate increase produced by cardioaccelerator nerve stimulation in anesthetized cats. ID50 values of TL-350 were 0.019 and 0.047 mumol/kg after i.v. and intraduodenal injection, respectively. This inhibition was reversed by either sulpiride (0.15 mumol/kg i.v.) or haloperidol (0.13 mumol/kg i.v.) but not by yohimbine (0.14 mumol/kg i.v.). TL-350 did not change isoproterenol-induced tachycardia and hypotensive responses. TL-350 caused dose-dependent decrease of arterial blood pressure and heart rate in anesthetized cats. Haloperidol (0.13 mumol/kg i.v.) prevented the hypotensive and bradycardic effects of the compound. TL-350 also produced concentration-dependent inhibition of heart rate responses to transmural stimulation of isolated cat right atria. IC50 value was 0.026 microM. Dopaminergic antagonists, haloperidol and sulpiride, antagonized the inhibitory effect of TL-350 in in vitro experiments. TL-350 did not stimulate presynaptic alpha-2 adrenergic receptors in rat vas deferens and guinea-pig ileum. TL-350 induced rotation for 3 hr in rats with unilateral denervated caudate nucleus. The compound was 0.5 as potent as apomorphine. In [3H]dopamine binding assays using rat caudate tissue, TL-350 had approximately the same activity as apomorphine in displacing the radioligand. It was concluded that TL-350 is a selective dopamine receptor agonist without possessing alpha and beta adrenergic receptor stimulating activity.

Animals↗
PubMed1982

Involvement of prostaglandin E and adenosine 3', 5'-monophosphate in lipopolysaccharide-stimulated collagenase release by rat Kupffer cells.

Kupffer cells exposed to bacterial lipopolysaccharide in vitro synthesized collagenase and released the major portion of it into the extracellular space while the intracellular level of enzyme was not altered significantly. Cycloheximide prevented the appearance of collagenase in the medium indicating de novo synthesis. Indomethacin, an inhibitor of cyclooxygenase, also blocked collagenase synthesis. In line with this observation. Kupffer cells were found to synthesize substantial amounts of prostaglandin E2 when exposed to lipopolysaccharide; concomitantly, cellular cAMP levels were increased. Indomethacin was shown to abolish the stimulated cAMP formation. Addition to the culture medium of cAMP or dibutyryladenosine 3', 5'-monophosphate as well as of prostaglandin E2 or, to a lesser extent, prostaglandin E1 allowed indomethacin-inhibited cells to resume the production of collagenase. It is proposed that in rat Kupffer cells lipopolysaccharide-elicited collagenase synthesis and excretion is mediated sequentially by stimulated production of prostaglandin E2, enhanced adenylate cyclase activity and increased intracellular cAMP levels.

Animals↗
PubMed1981

Future directions in dopaminergic nervous system and dopaminergic agonists.

The physiological and pharmacological roles of pre- and postsynaptic dopamine receptors in modification of neuronal transmission centrally and peripherally will be subjects for intense research during the next decade. As enumerated by Langer, dopamine-sensitive receptors have been described that may inhibit or facilitate release of neurotransmitter substances. It is likely that dopaminergic agents that are highly selective for specific transmitters will be discovered. Likewise, dopaminergic agents that are nonselective (i.e., that modify the function of two or more neurotransmitters) may offer many opportunities for modification of behavior.

Animals↗
PubMed1981

Cellular, molecular, and genetic characteristics of T cell reactivity to collagen in man.

Rheumatoid arthritis is significantly associated with the HLA determinant HLA-DRw4 and cell-mediated reactivity to collagen. To determine if genes linked to those coding for HLA-DRw4 constituted immune response genes for collagen reactivity, peripheral blood mononuclear cells from 20 individuals with rheumatoid arthritis, 13 individuals with other arthropathies, and 41 normal individuals were compared for their ability to synthesize the lymphokine leukocyte inhibition factor in response to denatured bovine collagen. All individuals were responsive to the control antigen Candida albicans. While 90% of the patients with rheumatoid arthritis responded to collagen, so did 30% of the individuals without rheumatoid arthritis. This included 15 normal individuals without any evidence of arthritis. Collagen responsiveness was dependent on interactions between T cells and macrophages was dependent on interactions between T cells and macrophages and was directed against determinants expressed by primary amino acid sequences in the synthetic polypeptide (Gly-Pro)n. HLA-DRw typing of 59 individuals revealed a highly significant relationship (P less than 0.0001, chi 2 = 33.7) between HLA-DRw4 and collagen responsiveness, irrespective of whether or not rheumatoid arthritis was present. All normal individuals who were HLA-DRw4-positive were collagen responders. These studies demonstrate that the cellular, molecular, and genetic characteristics of collagen reactivity in man parallel those documented for the T cell-dependent response to antigens under immune response gene control in rodents.

Arthritis, Rheumatoid↗
PubMed1981

Superoxide release by zymosan-stimulated rat Kupffer cells in vitro.

Kupffer cells were isolated from pronase-perfused rat livers and were maintained as a monolayer culture in a state of high purity and viability. Immediately after contact with zymosan particles, O2 uptake of the Kupffer cells increased fivefold; about 50% of the net oxygen consumed was accounted for as superoxide released into the medium. Concomitantly, a transient burst of luminol-dependent chemiluminescence, an increased activity of NAD(P)H oxidase and a stimulation of the flow of glucose through the hexose monophosphate shunt were observed. Chemiluminescence and O2- production were almost completely inhibited by superoxide dismutase and iodoacetate. Zymosan-induced chemiluminescence was not inhibited in the presence of the non-penetrating thiol reagents, 5,5'-dithio-bis-2-nitrobenzoate and iodoacetyl-sepharose. Iodoacetate acted on the cytosolic glucose-6-phosphate dehydrogenase rather than on NAD(P)H oxidase of the cell membrane.

Animals↗
PubMed1981

Age related changes and osteochondrosis in swine articular and epiphyseal cartilage: light ane electron microscopy.

Age related changes and osteochondrosis in swine were studied using light microscopy and electron microscopy in articular cartilage and light microscopy and epiphyseal cartilage of swine from three days to 30 weeks of age. Thickness, cellularity and vascularity of both the epiphyseal and articular cartilage, decreased as the swine aged. Osteochondrotic changes included formation of "plugs" of cartilage indicating localized failure of ossification and separation and space formation in epiphyseal cartilage. Eosinophilic streaks and space formation in epiphyseal cartilage was observed in relation to epiphyseal separation. Electron microscopy showed a continuous fibrillar layer on the surface of the cartilage corresponding to the lamina splendens of light microscopy. This layer increased in the thickness and showed accumulation of amorphous material between the fibrils with aging. In the matrix, the orientation and distribution of the collagen fibers changed with growth and thicker fibers with clear sub banding were more common in older age groups. Also, necrotic cells, glycogen containing bodies and cellular debris were noticed in the matrix of normal cartilage in old animals. Chondrocytes in the younger cartilage showed accumulation of organelles responsible for protein synthesis; while Golgi bodies, vesicles, lysosomes, well developed foot processes and other inclusions were noticed in older cartilage. Cartilage erosions had a clumped and disrupted lamina splendens on the surface and electron lucent patches in the ground substances of the matrix and chondrocyte cytoplasm.

Aging↗