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Biomedical subjects

M Azuma

Publications and source records attributed to M Azuma.

At least 325 records · Page 18Linked to original sources
PubMed1991

Amelioration of cataracts and proteolysis in cultured lenses by cysteine protease inhibitor E64.

Cataracts were produced in cultured rat lenses by either 10 microM calcium ionophore A23187, 25 microM sodium selenite, or 30 mM xylose. E64, an inhibitor of cysteine proteases, such as calpain (EC, 3.4.22.17), reduced severity of cataract and proteolysis of crystallins when included at a 500 microM concentration in the culture medium along with cataractogenic agents. Calpain II enzyme activity and the amount of calpain antigen were decreased in the cytosol of cataractous lens. However, E64 caused an increase in the amount of an 80-kD calpain subunit associated with the ethyleneglycol-bis-(beta-aminoethylether) tetraacetic acid/ethylenediaminetetraacetic acid-washed insoluble proteins when lenses were incubated with cataractous agents. These data indicate that E64 was at least partially effective in inhibiting lens calpain, and that activation of lens calpain may involve binding to the insoluble fraction. These results provide strong evidence for the activation of calpain in rodent cataracts and suggest testing inhibitors of calpain as anticataract drugs.

Animals↗
PubMed1991

[201Tl-reverse redistribution in a case with stunned myocardium].

A 58-year-old man was admitted to our hospital because of chest pain. Electrocardiogram showed giant negative T waves in leads I, II, III, aVl, aVf and V2 through V6. Echocardiogram showed anterior wall motion abnormality. Rest-redistribution thallium scan obtained 3 days after admission revealed reverse redistribution in antero-apical area. Coronary angiogram showed no significant stenotic lesions and left ventriculogram in chronic stage showed improvement of wall motion abnormality. Repeat thallium scan in chronic stage showed disappearance of perfusion defect in apical area. It was difficult to diagnose myocardial viability in our case with stunned myocardium because rest-redistribution thallium scan showed reverse redistribution. As the mechanism of this finding, early coronary recanalization in acute stage of the event was suspected.

Coronary Disease↗
PubMed1990

In vitro malignant conversion of low-grade rat urinary bladder carcinoma cells by exposure to N-methyl-N-nitrosourea.

The cause of deeply invasive human bladder carcinoma is unknown. Animal studies suggest that a malignant (invasive) conversion is inducible in low-grade noninvasive tumors by further exposure to a chemical carcinogen. To elucidate what molecular mechanism(s) is involved in the conversion, an in vitro system has been established in which conversion from low- to high-grade carcinoma can be induced. A rat bladder carcinoma cell line D44, derived from an N-methyl-N-nitrosourea (MNU)-induced low-grade noninvasive rat bladder carcinoma was used in the present investigation. Cloned D44 cells (D44c) were exposed to MNU, 50 to 400 micrograms/ml, for 1 h at 37 degrees C once a week for up to 6 weeks. After exposure to MNU, cells with altered morphology were cloned. The yield of altered clones was highest after a total dose of 150 to 200 micrograms of MNU used in 1 to 3 doses. Of 21 clones with altered morphology, 4 clones were further treated with MNU at the initial dose once a week for up to 3 weeks and then subcloned. Thirty-three of these subclones were examined for tumorigenicity in athymic nude mice. Twenty-seven formed highly invasive carcinomas, mostly squamous type, whereas the parental D44c cells failed to develop tumors upon inoculation. Pulmonary metastases were observed in 17 of the 27 clones. Plasminogen activator activity was elevated 4- to 9-fold as compared to parent D44c cells. ras p21 mutations at codon 12 were detected in 5 of 30 clones. These results indicate that the in vitro system described here may provide a useful model to study the molecular mechanisms involved in the conversion of noninvasive bladder carcinomas to metastasizing ones.

Animals↗
PubMed1990

Necessity of IgE antibodies and mast cells for manifestation of resistance against larval Haemaphysalis longicornis ticks in mice.

Genetically mast cell-deficient WBB6F1-W/Wv mice showed an apparent defect in manifestation of the resistance against larval Haemaphysalis longicornis ticks, but their serum IgE levels increased more than 100-fold after the second tick infestation. Immune sera obtained from the WBB6F1-W/Wv mice were adoptively transferred to the other WBB6F1-W/Wv mice which had received intracutaneous injections of WBB6F1-+/+ mouse-derived cultured mast cells. Because the resistance against ticks was detectable only when both mast cells and IgE antibodies were available, immediate hypersensitivity reaction appeared to have a physiologic role in the manifestation of the resistance against H. longicornis ticks.

Animals↗
PubMed1990

Calpain II in two in vivo models of sugar cataract.

Cataracts were produced in rat lenses by either feeding a diet containing 50% galactose or by inducing diabetic condition by intravenous injection of streptozotocin. Proteolysis of crystallins, protease activity of calpain II enzyme (EC 3.4.22.17), and presence of calpain molecule (antigen) were determined at four cataract stages--I, cortical vacuoles, II, vacuoles plus hazy cortex, III, nuclear cataract, and IV, mature cataracts. Calpain activity was normal or moderately elevated at early stages of galactose and diabetic cataracts. Later stages III and IV showed proteolysis of lens crystallins, increased proportion of insoluble proteins, loss of calpain enzyme activity and calpain molecule from the soluble fraction, and reduced amounts of calpain associated with insoluble pellet. In galactose cataract, the largest increase in lens calcium were found when proteolysis was present. These results provide evidence for calpain-induced proteolysis of lens crystallins in two in vivo models of sugar cataracts in rodents.

Animals↗
PubMed1990

Changes of egg retinoids during the development of Xenopus laevis.

The changes of egg retinoids during the development of Xenopus laevis were investigated by high-performance liquid chromatography (HPLC). All-trans retinal and 3-dehydroretinal are endogenous in the egg and are distributed to both the eyes and the ventral portion of the larval body. These retinals are converted to all-trans retinyl palmitate and 3-dehydroretinyl palmitate during the development up to stage 46. 11-cis retinal and 3-dehydroretinal can be detected after stage 40 in the eyes but not in the larval ventral portion. It is suggested that retinoids are transported from the larval ventral portion to the eyes after stage 41/42.

Animals↗
PubMed1990

Mitogenic activity of soluble preparations from Plasmodium berghei-infected erythrocytes to L3T4+, Lyt2- and L3T4-, Lyt2+ T-cell subsets.

The mitogenic activity of soluble preparations of Plasmodium berghei-infected erythrocytes (PBEP) in cultures of T or non-T cells isolated from spleens of naive mice was investigated. The proportion of cells at each phase in the cell cycle was examined by flow cytometry after incubation with various concentrations of PBEP; the proliferation index (PI-cell numbers at S, G2 and M phases/cell numbers at all phases x 100) was calculated. An addition of PBEP led to significant increases in the PI levels of T cells, but not in those of non-T cells. Moreover, when PBEP were added to L3T4+, Lyt2- (helper) or L3T4-, Lyt2+ (suppressor) T-cell fractions separated from rosette-forming T cells in spleens, significant increases in PI levels were detectable in both helper and suppressor T-cell cultures. These results indicate that PBEP have a mitogenic activity directed to both helper and suppressor T-cell fractions isolated from spleens of naive mice and that PBEP or Plasmodium parasites may in this way induce complicated immune responses during malaria infection.

Animals↗
PubMed1990

Effects of isoflurane on conduction velocity and maximum rate of rise of action potential upstroke in guinea pig papillary muscles.

This study was undertaken to determine whether isoflurane, a volatile anesthetic that is reported to possess a wide margin of cardiovascular safety, exerts electrophysiological effects on cardiac tissue. By use of standard microelectrode techniques, effects of isoflurane on the maximum rate of rise of action potential upstroke (Vmax) and conduction velocity were examined in guinea pig papillary muscles. Isoflurane decreased action potential amplitude and action potential duration in a concentration-dependent fashion. Isoflurane at 1.5 and 2.0 MAC decreased conduction velocity with as little influence on the maximum rate of rise of action potential upstroke as that exerted by halothane and enflurane. However, the effect of isoflurane in slowing intraventricular conduction was less than that of halothane and enflurane when compared at equi-MAC concentrations. Thus, isoflurane may be a safer anesthetic for the patients with intraventricular conduction abnormalities.

Action Potentials↗
PubMed1990

Stimulatory action of Ba2+ on catecholamine biosynthesis in cultured bovine adrenal chromaffin cells: possible relation to protein kinase C.

The effect of Ba2+ on the catecholamine biosynthetic activity was studied by measuring the formation of [14C]catecholamines from L-[14C]tyrosine in cultured adrenal chromaffin cells. In the absence of Ca2+, [14C]catecholamine formation was markedly stimulated by Ba2+, and this stimulation was observed in a manner dependent on its concentration. The stimulation of [14C]catecholamine formation by relatively low concentrations of Ba2+ was suppressed by polymyxin B, a typical inhibitor of Ca2+/phospholipid-dependent protein kinase (protein kinase C); and this inhibitory action of polymyxin B was attenuated by increasing the Ba2+ concentration. On the other hand, a tendency toward the enhancement of Ba2+-stimulated [14C]catecholamine formation was observed by a protein kinase C activator, 12-O-tetradecanoylphorbol 13-acetate (TPA). In contrast to the acute effect of TPA, [14C]catecholamine formation stimulated by Ba2+ was reduced by long-term exposure of chromaffin cells to a high concentration of TPA, which has already been reported to cause the reduction of protein kinase C activity as a result of the down-regulation of this enzyme. These findings suggest that Ba2+ stimulates catecholamine biosynthesis, probably through its direct action on protein kinase C in adrenal chromaffin cells.

Adrenal Glands↗
PubMed1990

Calpain and calpastatin in rabbit corneal epithelium.

The purpose of this study was to provide a direct assay for calpain and its endogenous inhibitor calpastatin in normal rabbit epithelium. Corneal epithelial extracts were fractionated by DEAE (1) chromatography on HPLC. Fractions were analyzed for calpain by ELISA, immunoblotting, and caseinolytic enzyme activity with FITC-labeled casein. Results demonstrated immunoreactive peaks for calpains I and II. Calpain II from the soluble fraction of corneal epithelium eluted at a similar NaCl concentration (260 mM) as calpain II from other tissues, was inhibited by both E64 and the removal of Ca, contained an 80 kDa subunit in immunoblots, and was present at specific activity of 220 units/g protein (in a crude homogenate). Calpain antigen was also present in the EDTA/EGTA washed insoluble fraction of corneal epithelium. Calpastatin in corneal epithelium eluted at 130 - 160 mM NaCl on DEAE, coeluted with calpain I, and was present at 330 units/g protein (crude homogenate). The results demonstrated a calpain/calpastatin system in corneal epithelium, where it is speculated to play a role in epithelial cell turnover and wound healing.

Animals↗
PubMed1990

[Evaluation of intrahepatic distribution of inferior mesenteric blood flow by transrectally administered 123I-IMP].

Intrahepatic distribution of the inferior mesenteric blood flow was evaluated with scintigraphy with transrectally administered 123I-iodoamphetamine (IMP). Twelve patients without liver diseases were studied. The IMP image was divided into 3 types; bilateral, left lobar predominant and right lobar predominant. Bilateral, left lobar predominant and right lobar predominant types were observed in 5, 5 and 2 patients respectively. Furthermore, uneven distribution pattern in the left or right lobe was observed in 2 of 5 patients with bilateral lobar type, 4 of 5 patients with left lobar predominant type and 1 of 2 patients with right lobar predominant type. In one patient with left lobar predominant type, repeat examination demonstrated bilateral lobar type. These results suggest that intrahepatic distribution of the inferior mesenteric blood flow is not uniform and consistent.

Administration, Rectal↗
PubMed1990

Effect of phosphate depletion on vasopressin secretion and kidney tissue vasopressin concentration in rats.

The effects of chronic phosphate depletion on vasopressin (ADH) secretion and kidney tissue ADH concentration were examined in rats fed on a diet containing 0.26% phosphorus (LP) or 0.99% phosphorus (NP). The concentration of plasma phosphorus (P) fell significantly in the LP rats after a 4-week period on the experimental diet. There was no significant difference between the LP and NP rats as regards their plasma ADH concentrations and kidney tissue ADH concentrations in normal hydration after a 4-week period on the experimental diets. Following hypertonic saline tests, the plasma ADH concentrations increased significantly in the LP and NP rats, but there was no significant difference between the groups. The kidney medulla and papilla ADH concentrations increased significantly with plasma ADH elevations in both groups. Again, no difference could be found in the cortico-medullary ADH concentration gradients between the two groups. These results indicate that chronic hypophosphatemia in phosphate depleted rats may not be related to ADH secretion and the distribution or tissue concentration of ADH in the kidney. Further, our data suggest that a low plasma P does not influence the ability of ADH to bind to kidney receptor in rats.

Animals↗
PubMed1990

[Pharmacokinetics of aztreonam on hemodialysis].

We studied the pharmacokinetics of aztreonam (AZT) in 6 patients with renal insufficiencies during nonhemodialysis and hemodialysis. After intravenous injection of 1 g AZT, it was found that serum AZT concentrations during hemodialysis were different from those during nonhemodialysis and serum half-lives (T 1/2 beta) were 3.44 hours and 16.97 hours, respectively. AZT clearance changed from 0.762 L/hr during hemodialysis to 3.360 L/hr during nonhemodialysis. These findings suggest that hemodialysis patients should receive the standard dose of AZT as a loading dose, followed by one-half the loading dose per day and receive a supplemental dose equal to half their usual maintenance dose after each dialysis session.

Aged↗