Biomedical subjects
J Black
Publications and source records attributed to J Black.
Mechanical behavior of articular cartilage quantitative changes with enzymatic alteration of the proteoglycan fraction.
The in-vitro viscoelastic mechanical response of normal rabbit articular cartilage is strongly dependent on the quantity and integrity of the proteoglycan fraction of the tissue matrix. Experimental results demonstrate that specific functional relationships exist between shear moduli, retardation time spectra, and proteoglycan content. Quantitative enzymolysis of the proteoglycan fraction of the tissue alters the form of these relationships in a fashion consistent with the altered physiochemical make-up of the tissue. The observed changes in mechanical behavior with controlled enzymolysis are similar to those associated with the early stages of osteoarthritis, rheumatoid arthritis, joint sepsis, and synovitis in animal models.
Biochemical and ultrastructural characterization of a novel cell structure associated with immunoglobulin secretion in B-lymphocytes.
In the companion paper, it was established that a secretory form of immunoglobulin, sIg, is present at or near the cell surface. This unexpected occurrence of sIg was postulated to be due to the labelling of sIg which remains temporarily associated with the cell packaged in a vesicle which appears to bud from the plasma membrane at a single pole of the cell. The question that is addressed in this report is whether or not this polar accumulation of sIg represents a common pathway for the exit of this protein which is used by antibody-producing cells. This question is important since, in spite of the fact that the intracellular events associated with immunoglobulin synthesis (processing and movement between subcellular compartments) have been defined, very little data exists on how or where immunoglobulin finally leaves the plasma cell. This question was approached here by first demonstrating that the polar immunoglobulin secretory vesicles (ISV) are associated with several sIg-producing cells including other hybridomas, B-cell lines, and mitogen-activated spleen cells. The second approach was to characterize the ISV on the cell ultrastructurally and to establish that these vesicles are released from the cell carrying with them sIg. Isolated vesicles released from biosynthetically labeled Ig-producing cells were analyzed by SDS-PAGE in order to confirm the presence of sIg and to determine the number of other proteins associated with the ISV, their molecular weights, and the degree of disulfide crosslinking of the molecules comprising this structure. Finally, the kinetics of sIg release was established by a pulse chase protocol for biosynthetically labeled cells, and by monitoring the release of radioactive Ig from surface iodinated cells. As was predicted from our biochemical studies of the ISV, we observed a very slow phase of sIg release as well as a rapid release phase. Our studies have established that at least one of the pathways for the release of Ig from hybridomas, B-cell lines, and normal splenic B-cells is via a polar multivesiculated structure that we have termed ISV, and that the sIg can be released either as a free form of the protein or packaged within a satellite vesicle which may release the sIg later and perhaps at considerable distance from the cell that produced it.
Types of consultations provided by a clinical pharmacokinetics service.
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Advertising in health care.
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Separation and identification of alkaline phosphatase isoenzymes and isoforms in serum of healthy persons by isoelectric focusing.
We have developed an isoelectric focusing procedure for resolving alkaline phosphatase (EC 3.1.3.1) isoenzymes and isoforms in serum. We use a thin-layer agarose gel film containing synthetic carrier ampholytes and a "separator" to flatten the pH gradient in the region of the isoenzyme and isoform isoelectric points. Sharp, highly resolved zones of enzyme activity are obtained by limiting diffusion; for this we rapidly couple the released product, 1-naphthol, to a diazonium salt, which forms a colored precipitate at the site of activity. We have resolved and identified 12 zones of alkaline phosphatase activity in the serum of ostensibly healthy persons within a wide age range. Theoretically, three basic isoenzymes are produced from independent gene loci: intestinal, placental, and nonspecific tissue alkaline phosphatase. The other zones of activity may be isoforms.
Resultant action of cimetidine in a cardiac adenylate cyclase assay: its elucidation by concentration-ratios analysis.
Cimetidine is widely used as a ligand for the classification of histamine H2-receptors in peripheral and central tissues. It demonstrates apparently simple competitive antagonism in isolated tissue assays and in brain adenylate cyclase assays. In this study its action in a cardiac adenylate cyclase assay was compared with its effects in the isolated guinea pig right atrial preparation. Using either histamine or impromidine, cimetidine expressed similar affinity (pKB = 6.1) in the intact tissue assay. In washed homogenates of guinea pig ventricle cimetidine appeared to antagonize competitively the stimulation by histamine of adenylate cyclase but the estimated pKB was 6.7. In contrast, the pKB for tiotidine was similar in both assays (7.7). Application of a recently developed concentration-ratios method indicated that cimetidine expressed a resultant action in the cyclase assay consisting of competitive H2-receptor antagonism and an additional inhibitory property involving a postreceptor action. The concentration-ratios analysis allowed the purely competitive component of cimetidine action to be quantified in the cyclase assay giving a pKB of 6.0.
Promoting AIDS awareness. A nursing perspective.
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Enhanced survival of rat neonatal cerebral cortical neurons at subatmospheric oxygen tensions in vitro.
In vitro tissue culture experiments are routinely performed at atmospheric oxygen tension (21%), although most cells experience lower oxygen tensions in vivo. The optimal oxygen tension for the survival of neurons and synthesis of neurofilament (NF) was determined using dissociated neonatal rat cerebral cortex and monoclonal antibodies to the 68 kDa and 200 kDa subunits of NF. Maximum production of each subunit determined by Enzyme-Linked Immunosorbant Assay occurred at 9% O2. Neuronal survival determined by immunohistochemistry was also maximal at 9% O2. CNS neurons are highly sensitive to oxygen tension and grow best at levels approximating capillary rather than atmospheric pO2.
Vegetable consumption and acute appendicitis.
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The calcium dependence of histamine, carbachol and potassium chloride-induced contraction in human airways in vitro.
The effect of depletion of calcium from the Krebs Henseleit (KH) solution and the addition of EDTA (1 mM) on contraction of human isolated bronchus by histamine, carbachol and potassium chloride (KCl) was examined. Contractions to histamine and carbachol were almost totally abolished in calcium free KH in the presence of 1 mM EDTA which only reduced KCl responses to 76% of control values. Verapamil (10(-6), 10(-5), 10(-4) M) decreased histamine and KCl contractile responses in a dose-related manner while having no significant effect on carbachol-induced tension. The intracellular calcium antagonist TMB8 10(-4) M caused a slight but significant decrease in histamine contraction but was without effect on the maximal response of the other two agonists. TMB8 decreased the potency of both histamine and carbachol. These results suggest that histamine, carbachol and KCl utilise different pools of calcium for contraction, that only part of the calcium entry for all agonists occurs via voltage-dependent calcium channels and that intracellular calcium stores may play a small role in contraction to these agonists.
Release of corrosion products by F-75 cobalt base alloy in the rat. II: Morbidity apparently associated with chromium release in vivo: a 120-day rat study.
There is concern whether in vivo corrosion of chromium-cobalt alloys releases ions containing trivalent [Cr(III)] or hexavalent [Cr(VI)] chromium. The question arises from indications that Cr(VI) is far more biologically active than Cr(III). Using a previously developed microsphere implant model, specimens of F-75 chromium-cobalt-molybdenum alloy were implanted in rats for periods up to 120 days. Blood and urine were collected at intervals during the study. Significant postoperative serum and urine chromium concentration elevations were observed. In addition, weight gain inhibition, lung morbidity, and animal mortality, related to the implant surface area to animal body weight ratio (SA/BW), were observed. Comparison of measured chromium serum concentrations with those concentrations found by others to be biologically active in tissue culture studies strongly suggests the release of Cr(VI) in this study.
Detection of oligoclonal IgG bands in unconcentrated CSF by isoelectric focusing in agarose gel and silver staining.
We analyzed 102 unconcentrated cerebrospinal fluids from a variety of neurologic diseases for oligoclonal IgG bands by isoelectric focusing in agarose gel followed by staining with silver. Ten to 12 microliter of cerebrospinal fluid containing 0.4-0.8 microgram of IgG was found to be optimum. Cerebrospinal fluid from 38 of 40 patients with clinically definite multiple sclerosis, 6 of 9 with suspected multiple sclerosis and 8 of 53 patients with other neurologic diseases had oligoclonal IgG bands by IEF in agarose followed by immunofixation. The commercial system employed here is a simple sensitive and rapid method for detection of oligoclonal bands in unconcentrated cerebrospinal fluid of patients with multiple sclerosis.
Effect of intrathecal morphine on the adrenocortical and hyperglycaemic responses to upper abdominal surgery.
Changes in plasma cortisol concentration and serum glucose concentration were measured in a group of 10 patients given intrathecal morphine 0.8 mg before cholecystectomy and the results compared with those from a control group of 10 patients receiving papaveretum i.v. during the operative procedure. Intrathecal morphine had no effect upon the hyperglycaemic response to surgery, but attenuated the increase in serum cortisol concentration.
Basic drug research in universities and industry.
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Receptors on human airway smooth muscle.
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