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Biomedical subjects

K D Bhoola

Publications and source records attributed to K D Bhoola.

At least 19 recordsLinked to original sources
PubMed1992

Immunovisualization of high (HK) and low (LK) molecular weight kininogens on isolated human neutrophils.

An immunocytochemical study was performed to examine the cellular localization and the subcellular distribution of kininogens in human blood cells. Kininogens were visualised using the immunogold-silver staining method and confocal scanning laser microscopy. We confirmed the existence of high molecular weight kininogen in human neutrophils and describe for the first time the presence of low molecular weight kininogen on these cells. Both high and low molecular weight kininogens were restricted to the neutrophils where they localized as clusters of immunogold particles on the cell membrane. No labeling was observed intracellularly in organelles such as mitochondria, endoplasmic reticulum, and azurophilic or specific granules after permeabilization of the neutrophils with Triton X-100, a procedure that permitted the visualization of elastase in the azurophilic granules. Clusters of high molecular weight kininogen molecules attached to the neutrophil surface could serve as receptors for plasma kallikrein and/or be the source of substrate for a discrete and circumscribed formation of kinins that may in turn facilitate the local diapedesis of neutrophils and the transudation of plasma constituents during acute inflammation.

Antibodies, Monoclonal↗
PubMed1992

Metabolism and characterisation of kinins and Hoe 140 (kinin antagonist) in the synovial fluid of patients with inflammatory joint diseases.

Methods have been optimised for the collection of synovial fluid and the chromatographic separation of individual kinins (bradykinin and kallidin) in the fluid by HPLC. In addition, the stability of the kinin antagonist, Hoe 140, in synovial fluid was compared with that of synthetic bradykinin. Although bradykinin was completely degraded after incubation for only 6 h in pooled synovial fluid obtained from patients with rheumatoid arthritis, Hoe 140 was stable for as long as 2 weeks under the same conditions. These studies will provide quantitative information regarding levels of kinins in inflamed joints and an insight into the therapeutic potential of kinin antagonists.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1992

Immunovisualisation of plasma prekallikrein and H-kininogen on human neutrophils and in human hepatocytes.

Both plasma prekallikrein and H-kininogen were immunolocalised in human hepatocytes by the use of immunocytochemical techniques in conjunction with the confocal optical scanning microscopy. In contrast, both proteins were demonstrated on the external surface of human blood neutrophils. However, detection of H-kininogen on non-fixed but not on fixed neutrophils with the anti-domain 6 antibody (directed at the prekallikrein binding site on H-kininogen), suggested that access to the epitope was blocked by the presence of the bound plasma prekallikrein. Therefore, we prepose that H-kininogen provides the binding site for plasma prekallikrein on circulating neutrophils.

Adult↗
PubMed1992

Cellular localization of human kininogens.

An immunocytochemical screening using polyclonal and monoclonal antikininogen antibodies was performed in various human tissues including blood cells. By comparing the spatial relationship between the cellular localizations of tissue kallikrein and kininogens it was evident that in some tissues both enzyme and substrate were present establishing a close anatomical relationship whereas in others only one of the components could be detected. This pattern of distribution suggests that within various tissues (cells) the major function of either tissue kallikrein (kininogenase, processing enzyme) or kininogen (kinin precursor, cysteine protease inhibitor, kallikrein acceptor molecule) could be different and probably specific to each cell type.

Amino Acid Sequence↗
PubMed1992

Kinins--key mediators in inflammatory arthritis?

Recent evidence suggests an important role for kinins in the generation of pain, swelling and the cellular damage associated with inflammatory joint disease. Kinins are considered to be pro-inflammatory peptides for a variety of reasons. They stimulate c fibres in the synovium to cause pain and increase extravasation of fluid to produce swelling. Kinins possess the capacity to release neurotransmitters (substance P, acetylcholine) and a second wave of mediators (interleukin-1, tumour necrosis factor, interleukin-8, prostaglandins, leukotrienes). The steady levels and turnover of kinins is regulated by formation (enzymic action of kininogenases on endogenous substrates called kininogens) and by metabolism (kininases, peptidases that hydrolyse kinins). These components of the kinin system can enter the synovial joint space either by transudation from the plasma or from degranulating neutrophils chemotactically attracted into the synovium from which they migrate into the synovial fluid. If kinins are involved, one would expect neutrophil derived mediators of the system to dominate in rheumatoid arthritis and psoriatic arthritis and plasma derived products to be more important in osteoarthritis and gout. But, the question whether any of the functions attributed to each component of the system can be considered to be a primary factor in the cellular pathology of inflamed joints remains to be established. Future investigations, including therapeutic trials with kinin antagonists and kallikrein inhibitors, will need to address the differential role of the kallikreins and kinins in the different types of synovitis, on symptoms of inflammation and on any remedial effects on the progression of tissue damage within the joint.

Amino Acid Sequence↗
PubMed1992

Bioregulatory role of the kallikrein-kinin system in the normal pituitary gland and its tumours.

Tissue kallikrein, a serine protease, is present in the prolactin-secreting cells of the normal anterior pituitary gland and pituitary adenomas. It is mainly located in the Golgi apparatus, but is also present in secretory granules. There is a distinct sexual dimorphism, with amount of tissue kallikrein being greater in anterior pituitary tissue from female rats. The intracellular levels of tissue kallikrein are increased by estradiol and in pituitary tumours, and decreased by ovariectomy, dopamine and its agonists. There is preliminary in vitro evidence that tissue kallikrein may be involved in the intracellular processing of the prolactin molecule before secretion. Tissue kallikrein synthesizes kinins which are present in the anterior pituitary and are capable of stimulating prolactin and growth hormone secretion by activating the phosphoinositide second messenger system. Prolactin physiology is uniquely linked to the kallikrein-kinin system in the normal pituitary and its tumours. Tissue kallikrein may have an important role in the pathophysiology of prolactin-secreting pituitary adenomas.

Adenoma↗
PubMed1992

Tissue kallikrein is associated with prolactin-secreting cells within human growth hormone-secreting adenomas.

Tissue kallikrein is a serine protease which may be involved in the intracellular processing of prolactin in the anterior pituitary gland. The expression of tissue kallikrein, in the rat, is promoted by oestrogen and inhibited by dopamine. Human and rat prolactinomas contain markedly increased amounts of tissue kallikrein; this is comparatively reduced if patients are pretreated with the dopamine agonist, bromocriptine, before surgery. Some GH-secreting adenomas are mixed and also contain prolactin-secreting cells. We therefore investigated 27 GH-immunostaining human pituitary adenomas for the presence of immunoreactive tissue kallikrein. Sixteen of the adenomas had positive immunostaining for prolactin; eight of these patients had associated clinical hyperprolactinaemia before the tumour was removed. Tissue kallikrein immunoreactivity was found in ten adenomas, all of which also had prolactin immunopositivity. There was a close relationship between the percentage of cells staining for prolactin and tissue kallikrein but not for GH. A further eight adenomas had patchy positivity, i.e. less than 1% of cells immunostained for tissue kallikrein and six of these also had some prolactin-staining cells. Nine out of eleven purely GH-staining adenomas had no tissue kallikrein immunopositivity, the remaining two showing patchy staining. A review of bromocriptine responsiveness, as assessed by mean GH hormone levels during oral glucose tolerance tests before and after therapy was commenced, indicated that patients with adenomas which stained for prolactin and tissue kallikrein were more likely to respond to bromocriptine than those which failed to do so.

Adenoma↗
PubMed1992

Mediators of joint swelling and damage in rheumatoid arthritis and pristane induced arthritis.

Joint swelling and tenderness in rheumatoid arthritis (RA) probably result from IgG aggregates activating complement with the consequent attraction of polymorphonuclear leucocytes (PMNs) and the liberation of their granule enzymes such as kininogenases. By contrast IL-1 and TNF are the major stimulants of cartilage and bone loss although other agents contribute. The fundamental drive for the production of these mediators is unknown but a role for heat shock proteins is suggested from work on pristane induced arthritis.

Animals↗
PubMed1992

An ontogenic study of renal tissue kallikrein in Okamoto spontaneously hypertensive rats: comparisons with human hypertensive nephropathy.

Urinary excretion of tissue kallikrein is reduced in essential hypertension. Although a similar finding has been reported in spontaneously hypertensive rats (SHR), only a few studies have been concerned with the amount of enzyme within the kidney both at the time of onset and during progression of the hypertension. We have performed an ontogenic study on the renal parenchymal values and immunoreactivity of tissue kallikrein in Okamoto SHR aged 4-78 weeks. Additionally, these two parameters were analysed in human biopsies taken from patients with hypertensive nephropathy. The enzymatic activity of renal tissue kallikrein (active and total; specifically antagonized by anti-tissue kallikrein antibodies), increased from 4 to 52 weeks in SHR when compared to normotensive Wistar Kyoto (WKY) rats; this increase was associated with a significant increase in blood pressure. In contrast, 78 weeks SHR and human biopsy tissue showed a substantial reduction in tissue kallikrein values. Also, both renal tissues showed a reduction in immunoreactivity in the cells of the connecting tubules that specifically store the enzyme. In advanced hypertension the observed reduction in tissue kallikrein was probably secondary to a loss of distal tubular mass, as a result of tubular atrophy and fibrosis. The greater values for renal tissue kallikrein in the kidney and reported reduced urinary excretion during the early phases of spontaneous hypertension may be explained by a primary defect in the mechanisms that regulate release of tissue kallikrein from the connecting tubule cells.

Animals↗
PubMed1992

Tissue kallikrein and the effect of bromocriptine in human prolactin and growth hormone-secreting pituitary adenomas.

Tissue kallikrein (TK) is present and co-localises with prolactin producing cells in human prolactinoma and mixed growth hormone (GH) and prolactin-secreting pituitary adenomas. TK immunoreactivity was reduced or absent in these types of adenomas from patients who had received the dopamine agonist, bromocriptine before surgery. Pure GH secreting adenomas had no TK immunoreactivity.

Adenoma↗
PubMed1992

Evidence that nitric oxide or a related substance is a neurovasodilator in the submandibular gland of the cat.

Close-arterial injection of L-NG-nitro arginine methyl ester, a compound that inhibits the synthesis of nitric oxide (NO), caused a dose-dependent reduction in both the parasympathetic and sympathetic (rebound) nerve-induced vasodilatation within the submandibular gland of the cat. At the same time, salivary secretion produced by each nerve was relatively unaffected, and the sympathetic vasoconstriction was enhanced. These results suggest that NO or a related compound may be either a neurotransmitter or neuromodulator contributing to the autonomic nerve-induced vasodilatation in the submandibular gland of the cat.

Animals↗
PubMed1992

Determination of tissue kallikrein and alpha 1-antitrypsin-tissue kallikrein complexes in synovial fluid of patients with rheumatoid, osteo and psoriatic arthritis.

An enzyme-linked immunosorbant assay was developed to determine tissue kallikrein and alpha 1-antitrypsin-tissue kallikrein complexes in pooled synovial fluid of patients with rheumatoid, osteo and psoriatic arthritis. Even though basal values could be determined, the addition of synovial fluid shifted the standard curves for both tissue kallikrein and alpha 1-antitrypsin-tissue kallikrein complex to the right, because of the presence of a novel inhibitor.

Arthritis, Psoriatic↗
PubMed1992

Comparison of plasma prekallikrein levels in human skin blister and chamber fluids from volunteer subjects and psoriatic patients.

Suction blisters were successfully raised on lesional, perilesional and non-lesional skin of psoriatic patients. Similar blisters were created on the skin of volunteer subjects. A specific method has been established for the measurement of plasma prekallikrein, and validated for blister fluid, skin chamber fluid, plasma and synovial fluid. Combined levels of plasma prekallikrein and its active form were compared in blister fluids obtained from psoriatic patients and the volunteers. Significantly higher values for plasma prekallikrein were found in the non-lesional blister fluids of psoriatic patients when compared to the volunteer subjects.

Blister↗
PubMed1991

Tissue kallikrein and kininogen in human sweat glands and psoriatic skin.

The cellular localization of immunoreactive tissue kallikrein and kininogen was studied in normal and psoriatic human skin. Immunoreactivity to both enzyme and substrate was observed in secretory granules of the dark cells in the secretory fundus (acinus) of the sweat glands. Double immunostaining revealed a segmental distribution of the two antigens. Each acinar section contained either tissue kallikrein or kininogen. However, there appeared to be a junctional zone in which both were present, but in separate dark cells. Immunoreactivity for both antigens was also observed in close apposition to the luminal microvilli of the duct cells. No specific immunostaining was seen in sebaceous glands, hair follicles, keratinocytes and other cells of the secretory unit such as myoepithelial or clear cells. In psoriatic skin there were in addition many neutrophils immunoreactive for tissue kallikrein in the epidermis and psoriatic scales. Mitogenic action of kinins may account to some extent for the characteristic accelerated turnover of epidermal cells in psoriasis and locally applied kinin antagonists may prove of value in the treatment of this disease.

Humans↗
PubMed1990

Cellular localisation of atrial natriuretic factor in the human kidney.

We have localised atrial natriuretic factor (ANF) in the human kidney by immunocytochemistry and radioimmunoassay. ANF is specifically visualised in the distal convoluted tubule cells and the intercalated cells of the connecting tubules and collecting ducts of the human nephron. The number of immunoreactive cells and tissue values for the peptide were compared between samples from normal kidneys and biopsies obtained from hypertensive patients, in whom the tissue ANF immunoreactivity was found to be reduced. Specific experiments are necessary to establish whether renal ANF is synthesised de novo or captured through endocytosis by the renal tubular cells. The possible functional roles of renal ANF are discussed.

Aged↗
PubMed1990

Electrolyte and humoral responses of renal transplant patients to head-out water immersion.

Eighteen renal transplant recipients and sixteen volunteers were subjected to the physiological manoeuvre of head-out water immersion, in order to compare changes in electrolyte and humoral responses known to occur in healthy individuals with those arising as a result of renal denervation in the transplant recipients. Although the tubular sodium response to water immersion was normal, tubular potassium excretion was markedly different in the transplant patients. Plasma values of atrial natriuretic factor increased in both groups and showed a close temporal relationship to urinary excretion of cyclic GMP. The attenuation in transplant recipients of the well-documented suppression of plasma renin activity during water immersion was probably due to a combination of factors, namely lack of renal innervation and an increase in circulating ANF. The small but significant increase in the excretion of enzymically active urinary kallikrein observed only in the transplant recipients during immersion still requires explanation.

Adult↗
PubMed1990

Characterization of a tissue kallikrein in human prolactin-secreting adenomas.

Immunoreactive tissue kallikrein was co-localized with prolactin in all the eleven prolactin-secreting adenomas of the human anterior pituitary gland examined in this study. The intracellular distribution of immunoreactivity in the prolactin-secreting cells suggests that tissue kallikrein is located within the Golgi complex of these cells. Both the intracellular hormone-processing action and the kininogenase activity of tissue kallikrein may be of functional importance in human prolactinomas.

Adolescent↗