Pasteurella dacryocystitis in rabbits.
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Animals↗
Biomedical subjects
S M Jones
Publications and source records attributed to S M Jones.
Fractionation of desmosomes and comparison of the polypeptide composition of desmosomes prepared from two bovine epithelial tissues.
Desmosomes isolated from bovine tongue mucosa or muzzle epidermis appeared identical by ultrastructural analyses but had some differences in their polypeptide compositions as determined by SDS-PAGE. These preparations were extracted in 9 M urea, 10 mM Tris-HCl (pH 9), and 25 mM B-mercaptoethanol and then centrifuged at 240,000g for 30 min. The urea-soluble and insoluble fractions were analyzed by SDS-PAGE. The urea soluble fractions of both tongue and muzzle desmosomes were enriched in polypeptides of 240, 210, 81, and 75 kDa and also polypeptides (40 to 70 kDa) that were keratin-like, as determined by immunoblotting analyses with keratin antisera. The urea insoluble fraction of tongue desmosomes contained glycoproteins of 165, 160, 140, 110, and 100 kDa, while this fraction from muzzle contained glycoproteins of 165, 115, and 105 kDa. Ultrastructural examinations of insoluble pellets obtained from urea extracted tongue and muzzle desmosomes showed that most of the components at the cytoplasmic faces of the desmosomes were removed, while the membrane regions of the desmosomes resisted the treatment. The urea soluble proteins were dialyzed against 10 mM Tris-HCl (pH 7.6), and the resulting preparation was pelleted by centrifugation and examined by electron microscopy. Ultrastructural examination of this material revealed that it had assembled into a fibrillar meshwork, similar to the fibrillar region adjacent to the submembranous plaque of isolated desmosomes. Thus, treatment of isolated desmosomes with 9 M urea allowed the fractionation of membrane-associated desmosomal proteins from cytoplasmic desmosomal proteins. A comparison of these fractions from tongue and muzzle indicated that the polypeptide compositions of the desmosomes varied between tissues, especially with respect to the fractions enriched in either glycoproteins or keratin.
Animals↗
Contractile responses of isolated adult rat and rabbit cardiac myocytes to isoproterenol and calcium.
Myocytes were isolated by Langendorff perfusion of rat or rabbit hearts with low calcium solution followed by collagenase and hyaluronidase, or by incubation of chunks of rat ventricular tissue in similar media. Cells were then placed in a bath on a microscope stage, superfused and electrically stimulated. Contraction amplitude and rate of change of length during contraction were measured using a video camera and edge detection monitor. Cells were selected for study using a number of criteria developed to identify and define a cell population able to give consistent inotropic responses over a long period. The maximum contraction amplitude with isoproterenol in rabbit cells was 0.244 micron (sarcomere length change) or 13.1% (percentage change in cell length), and the EC50 was 12.8 nM. The maximum contraction amplitude with isoproterenol did not differ significantly between rat and rabbit, between cells prepared by perfusion and those made from chunks, or when determined from non-cumulative rather than cumulative curves. The EC50 for isoproterenol in rat cells made by the perfusion method (cumulative curves) was 3.81 nM, significantly lower than in rabbit. The maximum amplitude obtained with increasing concentrations of calcium was not significantly different from that with isoproterenol under any condition. The EC50 for calcium averaged 2.78 mM in rat cells made by the perfusion method (cumulative curves) and was significantly greater than that in rabbit (1.4 mM). Maximum rates of contraction for rat cells averaged 4.59 micron/s in 8 mM calcium. Rat cells contracted faster than they relaxed, whereas rabbit cells in 8 mM calcium relaxed faster than they contracted. Rat cells, maximally activated by either calcium or isoproterenol, contracted significantly faster than rabbit. There was no difference in rates of contraction (or relaxation) between rat cells prepared by perfusion and those made from chunks of tissue.
Animals↗
Analysis of phosphorylation sites on branched-chain 2-keto acid dehydrogenase complex.
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3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)↗
Glutathione transferase activities of cultured human lymphocytes.
We have detected glutathione transferase (GST) activity towards 1-chloro-2,4-dinitrobenzene (CDNB) and benzo[a]-pyrene 4,5-oxide (BPO) in freshly isolated peripheral lymphocytes, phytohaemagglutinin (PHA)-stimulated lymphocytes, interleukin-2 (IL-2)-dependent T-cells and lymphoblastoid B-cell lines. The detection of conjugating activity with BPO implies the expression of a neutral, 'mu-like' GST form by both resting and cultured lymphocytes. In a sample of 12 unrelated individuals, BPO conjugating activity of freshly isolated lymphocytes showed a polymorphic distribution. In comparison with freshly isolated cells, BPO activity was increased 2- to 5-fold in IL-2-dependent T-cells and 4- to 10-fold in B-cell lines. The CDNB activity of T-cells was not significantly different to that of freshly isolated cells (P greater than 0.05) but activity in B-cell lines showed a significant increase (P less than 0.01). These data indicate that measurement of BPO activity in freshly isolated lymphocytes may allow the study of the human GST-mu polymorphism. However, IL-2-dependent culture of T-cells or viral immortalization of resting lymphocytes appears to cause the activation or induction of a GST form or forms which conjugate BPO efficiently. In the T-cells this effect may be mediated through addition of IL-2 to the culture since PHA treatment alone did not elevate activity.
Benzopyrenes↗
Effect of peritubular [Ca] or ionomycin on hydrosmotic response of CCTs to ADH or cAMP.
To evaluate in the mammalian kidney the effect of maneuvers thought to alter intracellular [Ca2+] on the hydraulic conductivity (Lp) response to vasopressin (VP) or 8-(p-chlorophenylthio)-adenosine 3',5'-cyclic monophosphate (ClPheS-cAMP), water flow was measured in isolated perfused rabbit cortical collecting tubules (CCTs) exposed to either varying bath [Ca] or ionomycin or quin 2-acetoxymethyl ester (AM). The development of the response to VP (20 microU/ml) was enhanced 28% by lowering Ca from 1.0 to 0.1 mM, but was not altered by increasing Ca from 1.0 to 3.75 mM. When measured in the same tubule, the maintenance phase of a previously established hormone response was inhibited by acutely raising peritubular Ca from 1.0 to 3.75 mM. Exposing the tubules to 0.1 mM Ca and 65 microM quin 2-AM, inhibited by 68% the development of the response to VP compared with that observed in tubules bathed in 1.0 mM Ca Ringer without quin 2-AM. In contrast, quin 2-AM and low peritubular Ca added during the maintenance phase enhanced the VP response by 50%. The Ca ionophore ionomycin (1.0 microM) reduced the development of the VP-elicited Lp by 65% and reversibly decreased by 42% the maintenance phase of the VP-stimulated Lp in a Ca-dependent manner. A longer exposure to the ionophore was required to inhibit the development and maintenance phases of the response to 10(-4) M ClPheS-cAMP. These results are consistent with the view that transient changes in intracellular [Ca2+] may be required for the development of the hormone response but that sustained increases in cytoplasmic Ca2+ levels inhibit the development as well as the maintenance phase of the hydrosmotic response to VP or cAMP in CCTs.
Algorithms↗
Inhibition of N-methyl-D-aspartate-induced hippocampal [3H]norepinephrine release by phencyclidine is dependent on potassium concentration.
This study examined the ability of phencyclidine (PCP) to inhibit the responses to N-methyl-D-aspartate (NMDA) in depolarizing concentrations of K+. The effects of PCP and Mg2+ on NMDA-induced norepinephrine release from hippocampal slices were measured during superfusion with various extracellular concentrations of K+. The IC50 values for Mg2+ and PCP were significantly higher in K+ concentrations above 6 mM. These data are supportive of the hypothesis that PCP produces a voltage-dependent blockade of NMDA-activated ion channels.
2-Amino-5-phosphonovalerate↗
Keratoconjunctivitis in the dog.
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Animals↗
Phosphorylation of branched-chain 2-oxo acid dehydrogenase complex in isolated hepatocytes.
Hepatocytes, isolated from rats fed a low-protein diet, were incubated with [32P]Pi and the phosphoproteins analysed. Immunoprecipitation using antibody against El of branched-chain 2-oxo acid dehydrogenase complex demonstrated phosphorylation of the alpha-subunit of El. Analysis of the tryptic phosphopeptides from the alpha-subunit indicated that two sites were phosphorylated. 4-methyl 2-oxopentanoate and DL-2-chloro 4-methylpentanoate decreased labelling of both sites. No major direct effects of several hormones on phosphorylation of branched-chain 2-oxo acid dehydrogenase was observed.
3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)↗
Cardiac transplantation: first-year experience in a community hospital.
The issue of decentralizing heart transplant services, formerly restricted to a few large medical centers, is currently under review by federal and state governments. We present the results of the first year of cardiac transplantation at a 385-bed community hospital. Twelve patients were selected according to generally accepted criteria from a pool of 24 referrals, all from within 75 miles of our institution. All patients were in New York Heart Association Class IV preoperatively. The one-year survival rate was found to be 82%, which is equivalent to that reported by established centers. All surviving patients were fully rehabilitated. Rates of infection and rejection were lower than expected, and costs were about half the national average. This series, in all likelihood, tests the limits to which the decentralization of cardiac transplant services can be taken. We conclude that cardiac transplantation can be accomplished at a community hospital with results, even for the first patients undergoing transplantation, comparable to those obtained by established programs at major medical centers.
Adult↗
Phencyclidine selectively inhibits N-methyl-D-aspartate-induced hippocampal [3H]norepinephrine release.
We have reported previously that phencyclidine (PCP) antagonizes N-methyl-D-aspartate (NMDA)-induced release of dopamine and acetylcholine from slices of rat striatum and nucleus accumbens. In the present experiments, we examined the effect of PCP on NMDA and kainic acid (KA)-induced release of [3H]norepinephrine (NE) from superfused rat hippocampal slices. NMDA and KA stimulated the efflux of NE with EC50 values of 192 and 245 microM, respectively. The presence of 1.2 mM MgCl2 in the buffer abolished NMDA-induced release but had little effect on KA-induced release. PCP inhibited the release of [3H]NE induced by 100 microM NMDA with an IC50 of 46 nM, but had no effect on the release of NE stimulated by 300 microM KA. 2-Aminophosphonovalerate antagonized NMDA-induced release, producing a parallel shift to the right in the concentration-response curve. However, PCP shifted the concentration-response curve to the right in a nonparallel fashion. Drugs with PCP-like properties, such as dexoxadrol and cyclazocine, inhibited NMDA-induced release, whereas related drugs such as levoxadrol, ethylketocyclazocine and morphine, which are not PCP-like, had no effect. These data suggest that PCP is a potent, selective, noncompetitive inhibitor of amino acid-induced [3H]NE release and that this action of PCP is mediated through the PCP/sigma receptor.
2-Amino-5-phosphonovalerate↗
Inhibition of human and rat lipoprotein lipase by high-density lipoprotein.
The hydrolysis in vitro of preactivated Intralipid (an artificial triacylglycerol-phospholipid emulsion) by rat adipose tissue lipoprotein lipase is inhibited by rat high-density lipoprotein (HDL). The aim of this work was to investigate whether human lipoprotein lipase was also inhibited, the mechanism of inhibition of the rat enzyme by HDL, and the role of the various individual apolipoproteins. Both human and rat lipoprotein lipase from post-heparin plasma are inhibited by HDL. This inhibition is considerably decreased if the HDL is first made 'apolipoprotein poor' by removal of some transferable apolipoproteins. In contrast, both native and apolipoprotein poor HDL inhibit the hydrolysis of Intralipid by rat hepatic lipase. Apolipoproteins C and E, either free in solution or attached to lipid vesicles, inhibit the hydrolysis of activated Intralipid by rat lipoprotein lipase to a maximum of 85% and 50%, respectively. Apolipoprotein A attached to vesicles gives little inhibition. HDL apolipoprotein and apolipoprotein C compete with the substrate for binding to lipoprotein lipase with apolipoprotein C having a higher affinity for the enzyme than HDL apolipoprotein. The inhibition of lipoprotein lipase by HDL can be explained by the association of the constituent apolipoproteins, in particular apolipoprotein C, with the enzyme so that there is less enzyme available to act on substrate.
Animals↗
Oxidative decarboxylation of 4-methylthio-2-oxobutyrate by branched-chain 2-oxo acid dehydrogenase complex.
Highly purified branched-chain 2-oxo acid dehydrogenase complex (BCOADC) oxidizes 4-methylthio-2-oxobutyrate and 2-oxobutyrate, with Km values of 67 microM and 18 microM respectively. The Vmax. for oxidation of these substrates is 27% and 53% respectively of that for 3-methyl-2-oxobutyrate. Highly purified pyruvate dehydrogenase complex (PDC) oxidizes 2-oxobutyrate (Km 100 microM; Vmax. 49% of that for pyruvate) but not 4-methylthio-2-oxobutyrate, whereas 2-oxoglutarate dehydrogenase complex will not utilize either 2-oxo acid as substrate. BCOADC kinase is inhibited by both 4-methylthio-2-oxobutyrate and 2-oxobutyrate, with half-maximal inhibition by 45 microM and 50 microM respectively. Phosphorylation of BCOADC in isolated adipocytes is inhibited by both 4-methylthio-2-oxobutyrate and 2-oxobutyrate, consistent with their inhibitory action of BCOADC kinase. Phosphorylation of PDC is decreased by 2-oxobutyrate, but not by 4-methylthio-2-oxobutyrate.
3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)↗
Phosphorylation of branched-chain 2-oxo acid dehydrogenase complex in isolated adipocytes. Effects of 2-oxo acids.
Isolated adipocytes from rat epididymal fat-pads were incubated with [32P]Pi, and intracellular phosphoproteins were then analysed by SDS/polyacrylamide-gel electrophoresis and autoradiography. A phosphorylated polypeptide of apparent Mr 46,000 was identified as the alpha-subunit of branched-chain 2-oxo acid dehydrogenase complex by immunoprecipitation using antiserum raised against the homogeneous E1 component of branched-chain 2-oxo acid dehydrogenase complex. Immunoprecipitation of this phosphoprotein is blocked in a competitive manner by purified branched-chain 2-oxo acid dehydrogenase complex. Peptide mapping of the isolated phosphoprotein indicates that two sites on the polypeptide are phosphorylated in the intact cells. Addition of branched-chain 2-oxo acids to the incubation medium causes diminution in the extent of labelling of both phosphorylation sites on the alpha-subunit, an effect presumably mediated via their known inhibitory action on branched-chain 2-oxo acid dehydrogenase kinase. These observations provide direct evidence for phosphorylation of branched-chain 2-oxo acid dehydrogenase complex in intact cells.
3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)↗
Antigenic changes in gp70 associated with the adult variant of Gross murine leukemia virus, WB91.
Gross murine leukemia virus (GV) is not leukemogenic in adult mice whereas a variant of GV, WB91, is highly leukemogenic regardless of the age of the inoculated animal. FACS and SDS-PAGE analysis have demonstrated that these viruses differ at least with respect to the env-encoded gp70 molecule. FACS analysis of virus infected or virus transformed cells with a type specific monoclonal antibody (mAb #55) indicated a difference in determinants associated with gp70 expressed by the two viruses. Rat antisera raised against GV- or WB91-induced tumor cells demonstrated that there were no crossreactive determinants between the gp70 molecules expressed on these tumor cells as recognized by the rat antisera. This difference in the gp70 molecules encoded by WB91 and GV may account for the ability of the WB91 virus to induce leukemia in adult mice, possibly by affecting the immunogenicity of the virus.
AKR murine leukemia virus↗
Giant orf in a normal individual.
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Child↗
Intermediate filament networks: organization and possible functions of a diverse group of cytoskeletal elements.
Immunofluorescence and electron microscopic observations demonstrate that intermediate filaments (IF) form cytoplasmic networks between the nucleus and cell surface in several types of cultured cells. Intermediate filaments interact with the nuclear surface, where they appear to terminate at the level of the nuclear envelope. From this region, they radiate towards the cell surface where they are closely associated with the plasma membrane. On the basis of these patterns of IF organization, we suggest that IF represent a cytoskeletal system interconnecting the cell surface with the nucleus. Furthermore, IF also appear to interact with other cytoskeletal components including microtubules and microfilaments. In the former case microtubule-IF interactions are seen in cytoplasmic regions between the nucleus and the cell membrane, whereas microfilament-IF interactions occur in the cortical cytoplasm. IF also appear to be cross-linked to each other; especially in the case of the IF bundles that occur in epithelial cells. In order to determine the molecular and biochemical bases of the organizational state of IF we have developed procedures for obtaining IF-enriched 'cytoskeletons' of cultured cells. In these preparations IF-nuclear and IF-cell surface associations are retained. Thus, these preparations have enabled us to begin to study various IF-associated structures (e.g. desmosomes) and associated proteins (IFAPs) using biochemical and immunological methodologies. To date, the results support the idea that IF and their associated proteins may comprise the cell type specific molecular infrastructure that is involved in transmitting and distributing information amongst the major cellular domains; the cell surface/extracellular matrix, the cytoplasm and the nuclear surface/nuclear matrix.
Actin Cytoskeleton↗
Reconstituted high density lipoprotein behaviour is modified by the nature of the lipid vesicle.
Apo HDL is a more potent inhibitor of lipoprotein lipase than native HDL. HDL reconstituted from apo HDL and vesicles made from either HDL total lipids or HDL phospholipids inhibits lipoprotein lipase in the same manner as native HDL. HDL reconstituted from apo HDL and vesicles made from phosphatidylcholine and sphingomyelin still behaves like apo HDL.
Animals↗