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Biomedical subjects

M Abe

Publications and source records attributed to M Abe.

At least 847 records · Page 47Linked to original sources
PubMed1992

Quercetin, an inhibitor of heat shock protein synthesis, inhibits the acquisition of thermotolerance in a human colon carcinoma cell line.

Here, we describe the effects of quercetin on the induction of thermotolerance as examined by colony forming assay in a cell line derived from human colon carcinoma (COLO320 DM). Cells became resistant to heat treatment at 45 degrees C when they were preheated at 42 degrees C for 1.5 h or at 45 degrees C for 10 min. This induction of thermotolerance was almost completely inhibited by continuous treatment with 100 microM quercetin during the first and second heating sessions, and the interval between. This effect of quercetin was demonstrated to be dose-dependent over a concentration range of 50-200 microM. Quercetin did not increase the thermosensitivity of non-tolerant cells. The presence of quercetin during the first conditioning heating was more effective in inhibiting thermotolerance than its presence during the second heating. Quercetin was also found to inhibit the acquisition of thermotolerance induced by sodium arsenite. Cycloheximide, a nonspecific inhibitor of protein synthesis, did not affect the acquisition of thermotolerance by the same cell line. Quercetin specifically inhibits the synthesis of all heat shock proteins so far reported previously, and this leads to inhibition of the induction of thermotolerance. Such inhibition of thermotolerance by quercetin may improve the efficacy of clinical fractionated hyperthermia.

Arsenic↗
PubMed1992

Selective renal tumour biopsy under ultrasonic guidance.

Selective renal biopsy under ultrasonic guidance has been used widely because it provides safe and accurate tissue sampling. Using this technique, we biopsied 36 renal tumours and obtained specimens in 35 cases. Histology of the biopsy coincided with that of the surgical specimen in 18/21 cases. Dissemination of tumour cells, thought to have been caused by needle biopsy and/or surgical manipulation, was observed in only 1 case of sarcoma. The method thus proved effective in determining treatment and it is suggested that it should be used in accordance with the criteria which we have devised.

Adult↗
PubMed1992

Carboxypeptidase M in brain and peripheral nerves.

Carboxypeptidase M (CPM), a plasma membrane-bound enzyme, cleaves C-terminal basic amino acids with a neutral pH optimum. We studied its distribution in human, baboon, and dog brain and in dog peripheral nerves. Areas were dissected, homogenized, centrifuged, and assayed for activity with dansyl-Ala-Arg. The corpus callosum and the pyramidal and optic tract were especially rich in CPM, whereas basal ganglia and cortex had low activity. The identity of the basic carboxypeptidase activity with CPM was shown by similarities in subcellular localization, membrane attachment, substrate hydrolysis, inhibition by a specific basic carboxypeptidase inhibitor, and cross-reaction with anti-human CPM antiserum. This antiserum immunoprecipitated an average of 85% of the activity in human and baboon brain and approximately 66% in dog brain. CPM co-purified with myelin extracted from the brain. Consistent with results obtained in placenta and cultured kidney cells, CPM in the brain appears to be membrane-bound via a phosphatidylinositol glycan anchor. In the peripheral nerves, the specific activity in dog sciatic nerve and in vagus was high (98 and 149 nmol/h/mg of protein, respectively). In immunohistochemical studies, glia in the brain, which appear to be oligodendrocytes or astrocytes, and the outer aspects of myelin sheaths and Schwann cells in sciatic and vagus nerves were stained. We conclude that in some areas of the CNS and the PNS, CPM is closely associated with myelin and myelin-forming cells. Northern blot analysis revealed the presence of mRNA coding for CPM in the brain, showing that the enzyme is indeed synthesized there.

3-Mercaptopropionic Acid↗
PubMed1992

Pharmacological characterization of 5-hydroxytryptamine-induced excitation of afferent cervical vagus nerve in anaesthetized rats.

1. An excitatory response to 5-hydroxytryptamine (5-HT) was measured from the afferent vagus nerve of anaesthetized rats. Measurements were determined by an extracellular recording from the whole nerve. 2. Intravenous bolus injection of 5-HT (1.56-100 micrograms kg-1) evoked a dose-dependent excitation of afferent vagus nerve activity. This response was blocked not only by a selective 5-HT3 receptor antagonist, GR38032F (10 and 100 micrograms kg-1), but also by a 5-HT2 receptor antagonist, ketanserin (10 and 100 micrograms kg-1). 3. Both a 5-HT3 receptor agonist, 2-methyl-5-HT (3.12-100 micrograms kg-1), and a 5-HT2 receptor agonist, alpha-methyl-5-HT (3.12-50 micrograms kg-1), produced a dose-dependent excitation of afferent vagus nerve activity. These excitatory effects were antagonized by GR38032F (10 micrograms kg-1) and ketanserin (10 micrograms kg-1), respectively. 4. A 5-HT1 like receptor agonist, 5-carboxamidotryptamine (50 micrograms kg-1), and a putative 5-HT4 receptor agonist, 5-methoxytryptamine (100 micrograms kg-1), failed to produce excitatory effects on the afferent vagus nerve. 5. These results suggest that the 5-HT-induced excitatory response of the afferent vagus nerve might be mediated not only via 5-HT3 receptors but also via 5-HT2 receptors in anaesthetized rats. It is unlikely, however, that either 5-HT1-like or putative 5-HT4 receptors are involved in the excitatory response of the afferent vagus nerve to 5-HT.

Animals↗
PubMed1992

Ionized calcium levels in coronary sinus blood during coronary angiography: effects of four contrast media.

The changes in ionized calcium level in the coronary sinus during coronary angiography were compared for four contrast media (meglumine sodium diatrizoate, iohexol, iopamidol, and meglumine sodium ioxaglate) in 44 subjects. Blood samples were collected before and 5, 15, and 30 seconds after injection of contrast medium into the left coronary artery. The hematocrit and ionized calcium level of each specimen were measured. Meglumine sodium diatrizoate produced the largest changes in hematocrit and ionized calcium level. The time-concentration curve of the hematocrit was similar for all four contrast media, but diatrizoate and ioxaglate produced a prolonged decrease of ionized calcium. The cause of this is not clear, but the phenomenon may be related to differences of ionic status among the contrast media. With respect to maintenance of the ionized calcium level, nonionic low-osmolality contrast medium with added calcium may be preferable for coronary angiography.

Adult↗
PubMed1992

Three-dimensional observations of accessory canals in mature and developing rat molar teeth.

The structure, distribution and formation of accessory canals in the developing and mature molar teeth of rat mandibular jaws were investigated with scanning electron microscopy and with three-dimensional image analysis using serial light-microscopic sections. In the initial stage of the accessory canal formation, most of the canals appeared in the gaps of the epithelial root sheaths formed by their approaching each other in the initial stage of the root formation. However, some of the canals appeared in the slits which may be formed by the destruction of the epithelial root sheath in the root apex regions. When the gaps and slits were invaded by blood vessels, the regions surrounding the vessels did not mineralize but became accessory canals. Usually, an accessory canal with one blood vessel connected the periodontal ligament to the dental pulp; however, in some cases, the canals were broken off midway following the destruction of the vessels.

Animals↗
PubMed1992

Cytoplasmic filaments in the endothelial cells of the sheathed capillary: an ultrastructural and immunocytochemical study in the pig spleen.

Cytoplasmic filaments of the endothelial cells of sheathed capillaries in the pig spleen were identified and their ultrastructure was studied. Two types of cytoplasmic filaments were found: intermediate filaments (diameter: 10 nm) which filled most of the interior of the cells, and thin filaments (diameter: 5 nm) which were located just beneath the cell membrane and filled the lateral cytoplasmic processes. In immunocytochemical preparations, the intermediate filaments were positive for vimentin and desmin, and were negative for keratin. Staining of the thin filaments with heavy meromyosin resulted in arrowhead formations. These observations suggest that the intermediate filaments maintain the cytoarchitecture, possibly protecting the cell from structural alterations induced by blood pressure changes. Concurrently, thin filaments may facilitate the passage of red blood cells and blood platelets through the interendothelial fenestrae of the sheathed endothelial cell to the reticular meshwork in the capillary sheath.

Animals↗
PubMed1992

Organic structures of the hypercalcified peritubular matrix in horse dentine.

EDTA-insoluble organic structures of the hypercalcified peritubular matrix (PM) in horse dentine were observed by scanning electron microscopy. The PM was enveloped in double cylindrical structures composed of fibrillar sheaths in the inner and outer peripheries. Between the outer fibrillar sheath and intrinsic fibrils of the intertubular matrix, a calcified cementing membrane existed. Within the PM, warped cone-shaped structures of fibrillar sheaths, overlapping at intervals of 4-6 microns and semiconcentrically surrounding the dentinal tubule, extended from the inner fibrillar towards the outer fibrillar sheath. The cone-shaped fibrillar sheaths following the inner and outer fibrillar sheaths were identified as the incremental lines of the PM. Most of these fibrils may be collagen although it could not be confirmed, whereas non-collagenous organic materials in the lateral branches of the dentinal tubule are radially arranged in the PM. These EDTA-insoluble structures were three-dimensionally illustrated using an image-analysing system.

Acid Etching, Dental↗
PubMed1992

Retroviral envelope glycoprotein (gp 70) is not a prerequisite for pathogenesis of primary immunoglobulin A nephropathy in ddY mice.

Deposition of a major retroviral envelope glycoprotein, gp 70, in renal glomeruli of ddY mice, an animal model for primary IgA nephropathy, was examined by immunofluorescence. The positive staining of gp 70 was not observed in glomeruli of our substrain of ddY mice at any ages examined using two different anti-gp 70 antisera and three different staining conditions, whereas deposition of IgA, IgG and IgM was manifest in mice aged over 40 weeks. As a control, NZB x NZW F1 mice from 4 months of age onwards showed severe glomerular deposition of gp 70, in keeping with previous reports. Thus, it appears that gp 70 deposition may not be sine qua non for the pathogenesis of IgA nephropathy of all substrains of ddY mice.

Animals↗
PubMed1992

Effects of a 5-lipoxygenase inhibitor, AA861, on lipoxygenase metabolism and superoxide anion generation by human polymorphonuclear leukocytes--potentiation of superoxide anion generation by LTB4.

We studied the influence of a selective 5-lipoxygenase inhibitor, AA861, on the generation of the superoxide anion (O2-) and the lipoxygenase metabolites by human polymorphonuclear leukocytes (PMN). PMN produce O2- in a dose-dependent manner following stimulation with arachidonic acid (AA), leukotriene B4 (LTB4), or C5a. When PMN were stimulated with one of those three agents in the presence of high doses of AA861 (1-10 micrograms/ml), a significant reduction of O2- release was observed. In contrast, the generation of O2- by PMN stimulated by LTB4 was potentiated at lower concentrations of AA861 (0.025-0.25 micrograms/ml). However, stimulation with AA or C5a did not influence O2- generation in the presence of AA861 at the same concentration range. Furthermore, treating the PMN with the cyclooxygenase inhibitor, acetylsalicylic acid, did not potentiate the generation of O2- by stimulation with LTB4 over a wide range of concentrations. Quantification of lipoxygenase metabolites by reverse-phase high-performance liquid chromatography revealed that a high concentration of AA861 (0.5-5 micrograms/ml) completely inhibited the production of LTB4 and its omega-oxidative metabolites by PMN following stimulation with 100 microM AA, but only partially inhibited that of 5-hydroxyeicosatetraenoic acid (5-HETE). AA861 at a concentration of 5 micrograms/ml significantly increased the production of 15-HETE by PMN following the same stimulation. AA861 did not influence catabolism of LTB4 added to the reaction mixture to its omega-oxidative products by PMN over a wide range of concentrations. These findings suggest that the inhibition of 5-lipoxygenase metabolism may stimulate 15-lipoxygenase in human PMN.(ABSTRACT TRUNCATED AT 250 WORDS)

Anions↗
PubMed1992

Hexahedrally based crystals in human tooth enamel.

Mg-containing calcium phosphate crystals including pseudocuboidal, rhombohedral shapes and groupings of quadrangular blades cubically arranged were found in human tooth enamel by scanning electron microscopy and by electron probe microanalysis. In caries-free old enamel, these hexahedrally based crystals measuring 0.5-2.5 microns in length were observed in some crevices of tufts and lamellae. The crystals were rarely seen in the inner crevices of caries-free exfoliated deciduous enamel and none could be seen in sound young enamel. In brown-coloured old enamel possessing arrested caries with lamellae, some of the lamellae contained crystals measuring 0.1-1.5 mu in length adjacent to half-dissolved prisms. These crystals, identified as Mg-containing whitlockite, will grow during a long period after eruption of the tooth or during the enamel caries process.

Aged↗
PubMed1992

Clinical significance of the calcification of coronary arteries in patients with angiographically normal coronary arteries.

In order to clarify the clinical significance of coronary calcification in patients with angiographically normal coronary arteries, exercise electrocardiography was used and left ventricular function was examined noninvasively and invasively. The patient groups were as follows: (1) patients with coronary artery calcification on only the left anterior descending artery but no narrowing lesion on any other arteries (calcified group), (2) patients with a significant stenosis on only the left anterior descending artery (stenotic group), and (3) the control group. The left ventricular function in the calcified group, as indicated by systolic time intervals and invasive parameters such as ejection fraction and mean systolic ejection rate, showed a depression similar to that in the stenotic group, compared with the control group. The incidence of electrocardiographically ischemic responses to exercise testing was significantly higher in the calcified group (75%, p less than 0.01) and the stenotic group (68%, p less than 0.01) than in the control group (25%). Exercise tolerance time and the maximum double product were markedly smaller in the calcified and the stenotic groups as compared with the control group. These results indicate that the left ventricular function and coronary reserve in the calcified group were reduced and almost identical with those in the stenotic group. The authors conclude that a calcified coronary artery, even if patent, cannot supply an adequate blood flow for the myocardium, resulting in impaired left ventricular function.

Angina Pectoris↗
PubMed1992

Functional and metabolic responses to ischemia in the isolated perfused hypothyroid rat heart.

It has been demonstrated that the V3 cardiac myosin isozyme has a higher efficiency and consumes less oxygen in doing mechanical work than the V1 myosin isozyme. The purpose of the present study is to investigate the functional and metabolic responses to ischemia following reperfusion of the hypothyroid heart, in which ventricular myosin isozyme is shifted from V1 predominance to V3 predominance. The heart was perfused by the working heart method for 15 min, and then global ischemia was induced for 10, 20 and 30 min with pacing at a rate of 320/min until cardiac cessation. The ischemic heart was reperfused for 30 min. The extent of recovery of pressure-rate product after reperfusion, following 20 min of ischemia in the hypothyroid heart, was higher than that in the control heart (p less than 0.01). The level of adenosine triphosphate (ATP) declined more slowly in the hypothyroid heart than in the control heart. The level of ATP and energy charge potential in the hypothyroid heart reperfused after 20 min of ischemia were higher than those in the reperfused control heart (p less than 0.01, p less than 0.05, respectively), though they did not differ from each other in preischemia. There were no significant differences in the levels of tissue lactate between the 2 hearts during ischemia and reperfusion. The recovery rate of the coronary flow of the 2 hearts did not differ from each other significantly. These data suggest that there is probability of the V3 predominant heart recovering from ischemic damage to the metabolism and cardiac function better than the V1 predominant heart because the transformation of myocardium, due to an increase in V3 into a slower but more efficiently working muscle results in conservation of tissue ATP during ischemia.

Adenosine Triphosphate↗
PubMed1992

The acyl-CoA synthetase inhibitor triacsin C enhanced eicosanoid release in leukocytes.

Triacsin C was previously reported to inhibit long-chain acyl-CoA synthetase and to reduce the production of acyl-CoA in rat neutrophils dose- and time-dependently. We found that preincubation with triacsin C inhibited the incorporation of labeled arachidonic acid into rat neutrophils. Furthermore, when triacsin C-treated neutrophils were stimulated with the Ca-ionophore A23187, they released an increased amount of eicosanoids into the culture medium. These results indicate that triacsin C suppressed acylation of arachidonic acid, which resulted in an increase in its metabolites.

Animals↗
PubMed1992

Assessment of endothelium-derived relaxing factor from human coronary arteries using the anti-platelet aggregatory effect.

Responses of human and canine washed platelets to thrombin in the presence and absence of human and canine coronary arteries were examined to establish a simple indirect measurement system for endothelium-derived relaxing factor (EDRF). Isolated rings of coronary arteries were obtained from either adult dogs or recipient hearts of cardiac transplant patients. The addition of small segments of canine and human coronary arteries with intact endothelia inhibited thrombin-induced platelet aggregation, but those with disrupted endothelia did not. Pretreatment of human and canine coronary arteries with the cyclo-oxygenase inhibitor indomethacin markedly attenuated the observed effect. The anti-platelet aggregatory effect of indomethacin-pretreated coronary artery was enhanced by acetylcholine or histamine, stimulators of EDRF production, or superoxide dismutase, which prolongs the half-life of EDRF, and inhibited by the EDRF inhibitor hemoglobin. These results suggest that endothelial cells of the human coronary artery, like the canine coronary artery, can produce EDRF which inhibits platelet aggregation, and that this simple experimental model is useful to examine the effect of environmental chemicals on EDRF in the human coronary artery.

Animals↗
PubMed1992

Injury to cultured human vascular endothelial cells by copper (CuSO4).

The effect of copper sulfate (CuSO4) on cultured human vascular endothelial (HVE) cells and cultured human fibroblasts (HAIN-55) was investigated. HVE cells were collected from umbilical veins by enzymatic digestion with collagenase. The viability, subsequent growth and DNA synthesis of both cell types were inhibited concentration-dependently by the addition of copper. The cytotoxic effect of copper on the morphology of these cells was also concentration-dependent. However, the cytotoxic effect of copper on the viability, subsequent growth and DNA synthesis was greater in HVE cells than in HAIN-55 cells. These results suggest that HVE cells are more susceptible to concentration-dependent copper cytotoxicity than HAIN-55 cells are, and that copper could induce vascular endothelial injury, which may be involved in the pathogenesis of cardiovascular disease.

Cardiovascular Diseases↗