Oxygen transport to tissue during recurrent blood flow supply by grouped capillaries in skeletal muscle with or without facilitated diffusion.
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Animals↗
Biomedical subjects
M Shibata
Publications and source records attributed to M Shibata.
Prepontine knife cut-induced hyperthermia in the rat. Effect of chemical sympathectomy and surgical denervation of brown adipose tissue.
The effect of brown adipose tissue (BAT) denervation on the prepontine knife cut-induced hyperthermia was studied. The knife cut has earlier been shown to induce a steady state hyperthermia of 3 to 4 degrees C, as a result of marked activation of the BAT. Before the lesion, the interscapular BAT (IBAT) temperature was lower than the colonic temperature, but the temperature gradient reversed a few minutes after the lesion and the fractional blood flow increased 12-fold. Bilateral sectioning of the 5 nerves supplying IBAT did not modify either the magnitude or the kinetics of the IBAT hyperthermic response. The IBAT fractional blood flow, which was 15 times higher in denervated than in intact tissue before the lesion, scarcely increased following the lesion despite the sharp increase in the tissue's metabolic activity. Chemical sympathectomy with 6-hydroxydopamine suppressed the hyperthermic response. Propranolol or hexamethonium injected i.v. during the steady state hyperthermia resulted in a rapid drop in IBAT temperature and in a reversal of the gradient between IBAT and colonic temperature both in denervated and in intact IBAT. Injection of desipramine, an inhibitor of noradrenaline reuptake, resulted in itself in an increase of temperature in both intact and denervated tissue, which is circumstantial evidence for the presence of a functional residual innervation in the latter.(ABSTRACT TRUNCATED AT 250 WORDS)
Adipose Tissue, Brown↗
Growth inhibition of Bacillus subtilis by basic dyes.
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Acridine Orange↗
Responses of anterior hypothalamic-preoptic thermosensitive neurons to locally applied capsaicin.
The effects of local application of capsaicin on the activity of single thermosensitive neurons in the anterior hypothalamic-preoptic area were studied in the urethane-anesthetized rat. Local injection of capsaicin through a cannula to the vicinity of the neurons increased the activity in 15 of 28 warm-units, decreased the activity in 2 of 4 cold-units and had no effect on 5 of 10 thermally-insensitive units. Electrophoretic application of capsaicin with the use of multibarrelled microelectrodes excited 16 of 27 warm-units, inhibited 12 of 17 cold-units and had no effect on 35 of 60 thermally-insensitive units. Progressive decreases in the responsiveness of the neurons to both capsaicin and the hypothalamic temperature were observed with repeated applications of capsaicin. Many neurons ceased firing after showing excitatory or inhibitory responses to single or repeated applications of capsaicin either by local injection or electrophoretic application. The results may explain the acute thermolytic response, as well as the subsequent decrease in responsiveness to the injection of capsaicin into the anterior hypothalamic-preoptic area, on the basis of changes in the activity of thermosensitive neurons in the anterior hypothalamic-preoptic area.
Animals↗
Responses of anterior hypothalamic-preoptic thermosensitive neurons to substance P and capsaicin.
The effects of capsaicin and substance P, applied locally, on the activity of thermosensitive and thermally-insensitive neurons in the anterior hypothalamic-preoptic area were studied with the use of multibarrelled microelectrodes in the urethane-anesthetized rat. In a total of 34 thermosensitive neurons (21 warm-units and 13 cold-units) in the anterior hypothalamic-preoptic area, only 7 units responded to substance P and 27 units (79.4%) were not affected. In contrast, 23 of 57 (40.4%) thermally-insensitive neurons responded to substance P. Of 74 thermosensitive and thermally-insensitive neurons tested with both substance P and capsaicin, only 7 units (9.5%) showed the same direction of change in activity in response to the application of both drugs. The majority of the neurons responded to only one of the drugs (32 units, 43.2%) or responded to substance P and capsaicin in opposite directions (9 units, 12.2%). A substance P antagonist, (D-Pro2, D-Trp7,9)-substance P, blocked the substance P-induced excitatory responses in 5 of 6 neurons tested in the anterior hypothalamic-preoptic area, but not the capsaicin-induced excitatory or inhibitory responses (n = 5). It is unlikely that substance P in the anterior hypothalamic-preoptic area participates in the hypothermic effects of capsaicin, observed after local injection.
Anesthesia↗
A molecular orbital study of a model of the Mg2+ coordination complex of the self splicing reaction of ribosomal RNA.
Recent discoveries have established the fact that RNA is capable of acting as an enzyme. In this study two different types of molecular orbital calculations, INDO and ab initio, were used in an attempt to assess the structural/functional role of the Mg2+ hydrated complex in ribozyme reactions. Preliminary studies indicate that the reaction is multistep and that the Mg2+ complex exerts a stabilizing effect on the intermediate or midpoint of the reaction.
Magnesium Compounds↗
Effects of interleukin-1 and arachidonate on the preoptic and anterior hypothalamic neurons.
Effects of microelectrophoretic application of ultrapure human interleukin-1 (IL-1), an endogenous pyrogen, on the activity of 80 neurons in the preoptic and anterior hypothalamus (PO/AH) were investigated in the urethane anesthetized rat. IL-1 predominantly decreased the activity of warm-sensitive neurons (15 of 19) and increased the activity of cold-sensitive neurons (10 of 12), but had no effect on 37 of 49 thermally insensitive neurons. The neuronal responses to IL-1 were blocked or attenuated by concurrent application of mepacrine (a phospholipase inhibitor) or sodium salicylate (a cyclooxygenase inhibitor). Local application of sodium arachidonate decreased the activity in 17 of 28 warm-units and excited 12 of 16 cold-units, and the effects of arachidonate were blocked by sodium salicylate. The results are compatible with the view that one or more cyclooxygenase metabolites of arachidonic acid are involved in the IL-1 induced fever.
Animals↗
Experimental comparison of vascularized and nonvascularized nerve grafting.
Previous studies have established the superiority of a vascularized nerve graft (VNG) over a nonvascularized nerve graft in a scarred recipient bed. This study compared the functional results of VNGs with nonvacularized nerve grafts (conventional nerve graft [CNG]) in a normal recipient bed. Forty rabbits were divided into two groups of 20 each. In one group a median nerve VNG was created in one forelimb. In the other group a CNG was created. Postoperative evaluation was performed at 10 and 24 weeks. Nerve conduction velocity, compound action potential area, axon diameter, and muscle weight did not demonstrate statistically significant differences. Axon counts and muscle strength did show a superior value for VNGs at 24 weeks.
Action Potentials↗
Lack of carcinogenicity of phenytoin in (C57BL/6 x C3H)F1 mice.
Groups of 50 B6C3F1 mice of each sex were given 0.012% or 0.006% phenytoin in their powdered diet for 78 wk and were then fed a basal diet for 8 wk. Control groups of 50 mice of each sex were fed powdered basal diet for 86 wk. Mean total intakes of phenytoin per mouse were 301 and 150 mg in males, and 292 and 154 mg in females, respectively. The survival rates of each group at week 86 were 72-86% in males, and 86-94% in females. Liver-cell tumors, alveolar tumors, and Harderian-gland adenomas in male mice, malignant lymphomas and/or leukemias in female mice, and a few tumors in other organs of both sexes were found. The total number of hepatocellular tumors in mice treated with the high dose of phenytoin was significantly smaller than that of control mice in males (p less than 0.05). However, hepatocellular carcinomas developed 15 to 3 wk earlier in a few mice of phenytoin-treated males than in the controls. In other organs, no significant increase of any particular tumor type was observed in the treated groups of both sexes. Thus, phenytoin was not carcinogenic in B6C3F1 mice in this study.
Administration, Oral↗
Genetically engineered modification of P450 monooxygenases: functional analysis of the amino-terminal hydrophobic region and hinge region of the P450/reductase fused enzyme.
Modified constructions of a microsomal cytochrome P450, of NADPH-cytochrome P450 reductase, and of a P450/reductase fused enzyme were prepared to analyze the function of the amino-terminal hydrophobic regions of these enzymes and the hinge region of the fused enzyme. Expression plasmids for delta P450c, delta reductase, and the delta P450/reductase fused enzyme, all of which lacked their amino-terminal hydrophobic regions, were constructed by inserting each of the corresponding cDNAs between the yeast alcohol dehydrogenase I promoter and the terminator of the expression vector pAAH5. Yeast transformed with plasmids encoding delta P450 and the delta P450/reductase fused enzyme produced smaller amounts of the respective enzymes and showed lower monooxygenase activity toward 7-ethoxycoumarin than did yeast transformed with plasmids encoding the complete enzymes. Both delta P450 and delta P450/reductase were found in the microsomal fraction of the yeast cells. Yeast transformed with the expression plasmid for delta reductase produced 20 times more enzyme than did yeast transformed with the plasmid for the complete enzyme. delta Reductase was present in the soluble fraction and was 33 times more active in reducing cytochrome c than was the complete enzyme. The results suggest that the amino-terminal hydrophobic regions of P450c and the P450/reductase fused enzyme play an important role in their stability and function in the yeast microsomes. By contrast, the amino-terminal-containing P450 reductase appears to be unstable in yeast cells. Altering the size of the hinge regions does not affect the activity of the P450/reductase fused enzyme significantly, but some amino acid changes in this region increase the stability of the fused enzyme slightly.
Animals↗
Extensible and less-extensible domains of connectin filaments in stretched vertebrate skeletal muscle sarcomeres as detected by immunofluorescence and immunoelectron microscopy using monoclonal antibodies.
Two kinds of monoclonal antibodies (3B9 and SM1) against connectin, muscle elastic protein, reacted with both alpha- and beta-connectins. Immunofluorescence studies revealed that 3B9 stained both edges of the A band of chicken breast muscle myofibrils and remained as such upon stretching to a sarcomere length of 3.5 microns. On the other hand, SM1 stained the I band very close to the edges of the A band and the SM1-stained stripes moved considerably upon stretching to a sarcomere length of 3.5 microns. Immunoelectron microscopic observations with frog semitendinosus muscle revealed that three distinct stripes bound with 3B9 in the edges of the A band did not move on stretching up to 3.5 microns. On the other hand, the two stripes stained with SM1 in the I band clearly moved to the same extent as the stretching. However, when a sarcomere was stretched to 4.0 microns, all the stripes with 3B9 or SM1 disappeared and diffused deposits of the antibodies were observed. Thus it is concluded that connectin filaments in the I band region are more extensible than those at both edges of the A band.
Animals↗
Survival and blood flow evaluation of canine venous flaps.
Using a canine model, we compared postoperative viability of saphenous venous flaps, cephalic venous flaps, and composite-tissue grafts without vascular connections. Of the saphenous flaps, 14 percent survived. Of the flaps based on the cephalic vein, 75 percent survived. Cephalic composite-tissue grafts were 13 percent successful. The presence of a more intricate venous plexus in a flap seems to increase its chances of success. Arterial injections of radioisotope-labeled microspheres were used to chart revascularization in cephalic flaps. These flaps demonstrated arterial blood flow by day 3, while the composite grafts showed no flow until day 7. Venous injections of microspheres distal to the flap were used to test vein-to-capillary blood flow. No significant entrapment of microspheres within the flaps occurred at any time, suggesting such flow to be inadequate.
Animals↗
Histopathological and immunohistochemical studies on nickel sulfide-induced tumors in F344 rats.
Twenty-five tumors induced in F344 male rats were examined histologically and immunohistochemically using antibodies against myoglobin, myosin, desmin and cathepsin B. Eight were from rats which had been given intramuscular (im) injection and 17 were from rats which had been given subcutaneous (sc) injection of 5 mg of Ni3S2. Among 10 rhabdomyosarcomas, myoglobin was detectable in 3, myosin in 8, and desmin in all, but cathepsin B was present in none. Out of 8 malignant fibrous histiocytomas, cathepsin B was detectable in all, but the other antigens were absent. In a leiomyosarcoma, only desmin was detected. In two fibrosarcomas, none of the markers were detected. In four undetermined tumors, one reacted only with anti-desmin antibody, two with only anti-cathepsin B antibody, and one with none of the antibodies. Of the three myogenic markers utilized in this study, anti-desmin antibody appeared to be the most sensitive. Cathepsin B was found mainly in the histiocytic cells of malignant fibrous histiocytoma. Thus, desmin appears to be particularly valuable in distinguishing immature myogenic tumors from other primitive tumors, while cathepsin B is useful in distinguishing malignant fibrous histiocytoma from other pleomorphic mesenchymal tumors.
Animals↗
Wide-spectrum initiation models: possible applications to medium-term multiple organ bioassays for carcinogenesis modifiers.
Two wide-spectrum initiation models were investigated in F344 male rats. Model I: After sequential treatment with diethylnitrosamine (DEN), N-methylnitrosourea (MNU) and dihydroxy-di-N-propylnitrosamine (DHPN), animals were given phenobarbital (PB) or N,N-dibutylnitrosamine (DBN) as a test compound for 14 weeks and sacrificed at week 18. Model II: Animals were treated with DHPN, followed by N-ethyl-N-hydroxyethylnitrosamine (EHEN), and then 3,2'-dimethyl-4-aminobiphenyl (DMAB) as initiators and were subsequently given 3-methylcholanthrene (MCA) or PB as a test compound for 11 weeks. Animals were sacrificed 16 weeks after the commencement. In both models, assessment of lesion yield revealed significant enhancement of carcinogenesis by the test compounds in their respective target organs. Since, in many cases, treatment with PB, DBN and MCA subsequent to the combined initiation procedures brought about a marked increase in lesion development, far greater than a simple sum of the yields given by initiators and test compounds alone, the presently described approach appears promising for development of medium-term bioassay systems for detection of environmental carcinogens.
Animals↗
[Blood reflux into cartridge in dental anesthesia. Detection of total protein and human hemoglobin in residual anesthetic solution].
The present study was designed to elucidate the blood reflux into cartridge under infiltration anesthesia. When imitation examination was carried out using pontamine blue dye solution in 7 kinds of syringes for the use of cartridge, dye reflux was observed in all of them. Compared 4 kinds of cartridges on the market, dye reflux was observed in all except one. The amounts of protein in residual anesthetic solution of cartridges after infiltration anesthesia were quantitatively measured by dye binding method. Human hemoglobin was also measured by enzyme immunoassay (EIA). The detection rates of protein and human hemoglobin were 26.2% (85/324) and 24.2% (24/99), respectively. From these facts that blood reflux cannot be avoided in the cartridge system, it is necessary to prohibit the reuse of residual anesthetic solution of cartridge as quickly as possible to avert the risk of cross infection of HB and AIDS virus.
Acquired Immunodeficiency Syndrome↗
Characteristics of M-GTFI, a new inhibitor of Streptococcus mutans glucosyltransferase.
M-GTFI, originally screened as an inhibitor of Streptococcus mutans glucosyltransferase, strongly inhibited alpha-glucosidase, in a non-competitive manner especially when the synthetic substrate p-nitrophenyl-alpha-D-glucopyranoside was used. It also inhibited beta-glucosidase, beta-amylase and, to a lesser extent, beta-glucuronidase. The inhibitor was stable in neutral and alkaline pH ranges and dependency of the inhibition on pH and temperature was not observed. Some proteinases and polysaccharides-hydrolyzing enzymes as well as human saliva did not inactivate the inhibitor. There was a correlation between the release of sulfate anions from the inhibitor molecule on incubation with HCl (0.2 N) at 100 degrees C and loss of inhibitory properties of the molecule. It is suggested that the presence of sulfate ester linkages in the inhibitor molecule play an important role in the inhibition process.
Enzyme Inhibitors↗
Roles of fluid shear stress in physiological regulation of vascular structure and function.
The effects of fluid shear stress on the function and structure of the vascular system are outlined, based on the findings obtained in our laboratory or of our colleagues. First, it is pointed out that the adaptive response of the vascular wall to flow changes which we observed in the canine carotid artery shunted with the jugular vein altering the internal diameter to keep the wall shear stress constant, can attain the optimum vascular branching structure as predicted in the minimum work model by Murray. Electronmicroscopic studies of similarly shunted arteries revealing various morphological changes in the endothelial cells have suggested that the shear stress initially affects the endothelium. The in vitro experiments using cultured endothelial cells as well have exhibited that the mitotic activity of the cells significantly increases by applying fluid shear stress. From these findings, it is concluded that the adaptive response of the endothelium to the fluid shear stress is an inherent and key process locally regulating the vascular system to be in the most functional state.
Animals↗
[Mother-to-infant transmission of human retroviruses].
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Female↗