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Biomedical subjects

N Katoh

Publications and source records attributed to N Katoh.

At least 163 records · Page 9Linked to original sources
PubMed1989

Radiation protection by Shigoka extract on split-dose irradiation in mice.

Radioprotective effect of a Shigoka extract was studied on split-dose irradiation. Mice were exposed to 4 Gy X 4 or 3 Gy X 4 for examining survival ratio or hemogram, respectively. The extract was i.p. injected immediately after each irradiation. The extract significantly (p less than 0.001) increased the survival ratio, and it increased leukocyte count within the period of the death (days 2-12 after the final exposure). Cerebral hemorrhage after 4 Gy X 4 was diminished by the extract. Recovery of leukocytogenesis seems much more important for survival at split-dose irradiation than at single acute irradiation.

Animals↗
PubMed1989

Inhibition by gossypol of cyclic nucleotide-independent phosvitin kinase from pig testis.

Gossypol, a male anti-fertility agent, was found to be an inhibitor of cyclic nucleotide-independent phosvitin kinase from pig testis. The IC50 value (concentration causing 50% inhibition) was 42 microM using phosvitin as substrate. Kinetic analysis indicated that the compound inhibited the enzyme noncompetitively with respect to ATP (Ki = 17 microM) and competitively with respect to phosvitin (Ki = 11 microM). The gossypol inhibition was reversed by the addition of polyamines. The compound also inhibited phosphorylation of high mobility group (HMG) proteins HMG 14 and 17 (the endogenous substrates in the testis located in nucleosome), with an IC50 value of 48 microM.

Animals↗
PubMed1989

Retinol transport system in cattle and purification of retinol-binding protein from bovine serum.

Retinol transport system in cattle was investigated, followed by the purification and characterization of bovine serum retinol-binding protein (RBP). Gel filtration of serum from cow produced two retinol peaks, peak 1 and 2. The major, peak 1 having higher molecular weight corresponded to the retinol peak from human serum which consisted of RBP and prealbumin (PA). The peak 2 which was not presented in the human serum had lower molecular weight (about 20,000). In the presence of 3.0 M urea, the peak 1 was almost disappeared and peak 2 was increased. On the other hand, in the serum from calf, major retinol peak was corresponded to the peak 2 from cow. These results suggested that, in cow, retinol was transported by the complex of RBP and another protein, presumably PA, but in calf, mainly by RBP alone. Purification of bovine RBP was carried out by using four chromatographic steps as follows; 1. DEAE-cellulose (pH 6.0), 2. Sephadex G-100 (using the buffer containing 3.0 M urea), 3. DEAE-cellulose (pH 8.3), 4. Sephadex G-100. From 1,100 ml of serum, 14.1 mg of bovine RBP was finally obtained and the overall recovery was estimated to be about 32%. Its molecular weight, ultraviolet absorption and fluorescence spectra, electrophoretic mobility, and amino acid composition were similar to those of other species.

Amino Acids↗
PubMed1989

Contribution of leucocytes to the origin of lactate dehydrogenase isozymes in milk of bovine mastitis.

The isozyme patterns of lactate dehydrogenase (LDH) of bovine milks are different in normal (LDH1 is predominant) and mastitic milks. We surveyed LDH isozymes of mastitic milks, and found that the isozyme patterns could be separated into two groups, mastitic milk A (higher proportions of LDH1,2 and lower proportions of LDH3-5) and mastitic milk B (relative decrease of LDH1 and increase of LDH2-5, particularly LDH3-5). To elucidate the origin of LDH isozymes in the mastitic milks, the isozyme patterns of granulocytes, monocytes, platelets and lymphocytes (T and B cells) were examined. The patterns of granulocytes and lymphocytes were similar to those of mastitic milks A and B, respectively. Sodium dodecyl sulfate polyacrylamide gel electrophoresis also showed the presence of marker proteins of granulocytes and lymphocytes in mastitic milks A and B, respectively. These results suggested that granulocytes and lymphocytes at least partly contributed to the origin of LDH isozymes in the mastitic milks.

Animals↗
PubMed1989

Clinical significance of exercise-induced negative U-waves in patients with anterior myocardial infarction.

To elucidate the clinical significance of the exercise-induced negative U-wave (NU) in patients with anterior myocardial infarction, we compared the angiographic and scintigraphic findings in 15 patients with and 20 patients without NU, and obtained the following results: 1) On coronary angiography, all patients in the NU (+) group showed over 90% stenosis or total occlusion of the left anterior descending coronary artery (LAD). In the latter cases moderate to abundant collaterals were visualized on the anterior wall. In contrast, such a tendency was not observed in the NU (-) group. 2) Segments composed of viable myocardium (estimated by preservation of contraction at rest and T1-201 redistribution after exercise) numbered 30 of 45 segments (67%) in the NU (+) group, and 13 of 60 segments (22%) in the NU (-) group. Segments composed of lost myocardium (estimated by loss of contraction at rest and persistent defect in T1-201 uptake) numbered 7 of 45 segments (16%) in the NU (+) group, and 38 of 60 segments (63%) in the NU (-) group. 3) Exercise-induced NU was frequently observed on R-wave preserved leads with ST depression, but was also observed over abnormal Q waves, ST elevation and in isolation in some instances. 4) In 3 patients, preexisting exercise-induced NU was no longer observed and a transient stress-induced T1-201 defect disappeared after successful LAD revascularization. In conclusion, exercise-induced NU on precordial leads in patients with anterior myocardial infarction may be a sign suggesting the presence of jeopardized, but still salvageable, myocardium in the infarcted area.

Aged↗
PubMed1989

Applications of combination wavelength (1060-nm and 530-nm) and pulsed Nd:YAG laser for contact laser surgery.

Two pulsed neodimium yittrium aluminum garnet (Nd:YAG) laser systems were evaluated for contact surgery through a fiberoptic system with a sapphire tip. Pulsed Nd:YAG laser at 1060 nm was as effective as continuous-wave Nd:YAG laser in producing tissue incisions. A combination of 1060-nm and 530-nm wavelengths achieved smooth cutting at lower energy levels. Corneal endothelial cell damage occurred at the high power level (7 watts) required for smooth underwater incisions with both continuous wave and pulsed lasers.

Animals↗
PubMed1989

Choroidal vascular repair following orange dye laser photocoagulation.

In order to evaluate the effect of laser photocoagulation on choroidal vessels, moderate laser burns were performed on monkey fundi with a dye orange beam (595 nm) at various intervals for a period of 60 days. After photocoagulation, choroidal vascular casts were prepared by injection of Mercox resin into the carotid arteries, and then observed by scanning electron microscopy. Immediately after photocoagulation, filling defects of the choriocapillaris and medium-sized choroidal vessels were seen in all lesions. By three to five days, restoration of the choroidal microcirculation in the laser lesions had begun. At seven to ten days, filling defects of the choriocapillaris had gradually become undemarcated. By 2 weeks, the sites of the former filling defects were occupied by a loose network of capillaries. At 60 days, the laser lesions had been entirely replaced by newly formed choriocapillaris, composed of narrower lumina and showing a more irregular lobular pattern than normal choriocapillaris.

Animals↗
PubMed1989

Decreased protein kinase C activity in fatty liver from cattle.

Protein kinase (PK) C activity in the liver of cattle with fatty liver syndrome was evaluated and compared with that in liver of healthy cattle. The PKC activities in cytosolic and particulate fractions were reduced in fatty livers, compared with those in livers from healthy cattle. The decrease of PKC activity was more distinct in cytosolic (P = 0.0016) than particulate (P = 0.069) fractions. Protein kinase activities other than PKC were not substantially changed. Seemingly, PKC was involved in the pathogenesis of fatty liver syndrome in cattle.

Animals↗
PubMed1988

Cardiac rhabdomyoma. A case report with reference to atrial natriuretic peptide.

An autopsy case of cardiac rhabdomyoma in a male infant is reported. Many nodules of rhabdomyoma were present in all four cardiac chambers and were microscopically composed of ovoid, glycogen-laden cells and typical "spider cells". Atrial natriuretic peptide (ANP) was immunohistochemically demonstrated in both normal myocytes and rhabdomyoma cells of both atria, but not in normal myocytes and rhabdomyoma cells of both ventricles. Ultrastructurally, atrial specific granules were present in atrial rhabdomyoma cells and normal atrial cardiocytes, and these showed ANP immunoreactivity with protein A-gold technique. It could be said that the localization and intracellular distribution of ANP in this cardiac rhabdomyoma were closely similar to those of normal human heart. With regard to the presence of ANP, cardiac rhabdomyoma cells arising in atria seemed to differ from those in ventricles, although many tumor nodules occurred in both atria and ventricles. Furthermore, it seemed that cardiac rhabdomyomas could also be divided into two parts: 1) an atrial part with ANP, and 2) a ventricular part without ANP. Therefore, this study confirms the hypothesis that cardiac rhabdomyoma is a hamartoma rather than a true neoplasm.

Atrial Natriuretic Factor↗
PubMed1988

Effect of nitroglycerin on aortic impedance, diameter, and pulse-wave velocity.

The effects of an intravenous infusion of 1 microgram/kg/min nitroglycerin were studied on systemic arterial properties in nine acutely instrumented dogs. Aortic impedance and pulse-wave velocity were calculated from measured pressure and flow signals collected during random ventricular pacing. Central aortic diameter was simultaneously determined with ultrasonic dimension crystals. Mean blood pressure was maintained constant to avoid the confounding effects of passive, pressure-induced changes in vascular properties. Nitroglycerin both reduced the amplitude of peripheral vascular reflections and delayed the return of these reflections to the aortic root. This reflection delay was manifested as a consistent leftward shift in both impedance modulus and phase. The magnitude of this reflection delay could not be entirely accounted for on the basis of the measured changes in average pulse-wave velocity along the aorta.

Animals↗
PubMed1988

Effects of laser wavelengths on experimental retinal detachments and retinal vessels.

We studied the effects of the yellow (577 nm), orange (595 nm) and red (630 nm) dye lasers, the argon blue-green (488, 514.5 nm) and green (514.5 nm) lasers, and the krypton red (647 nm) laser on experimentally produced serous and hemorrhagic retinal detachments and on retinal vessels in rabbits. Retinal detachments were created by either injecting balanced saline solution or partially hemolyzed blood under the retina. All laser wavelengths except the argon blue-green bypassed the sensory retina and produced no damage on either the sensory retina or the underlying retinal pigment epithelium with serous retinal detachment. Each laser wavelength, however, produced a specific effect on the detached retina with hemorrhagic fluid. Blue-green, green, yellow and orange wavelengths damaged the sensory retina more severely than the red wavelengths. Laser coagulation of the retinal vessels with the blue-green, green and orange wavelengths produced vasospasms.

Animals↗
PubMed1987

Protein kinase C phosphorylation of protamine is Ca2+ independent, but the addition of DNA renders it Ca2+ dependent.

Protamine is a unique substrate of protein kinase C for its Ca2+-independent phosphorylation. The interaction between protein kinase C and protamine and the effect of DNA on the interaction was studied. Protein kinase C was retained in a protamine-immobilized Sepharose 4B column, even in the absence of Ca2+ and was eluted with ammonium sulfate or L-arginine. The eluted enzyme was fully activated by phosphatidylserine alone, when protamine was used as substrate. When DNA was included in the assay system, the activity elicited by phosphatidylserine alone was inhibited. The DNA effect on the activity in the presence of both Ca2+ and phosphatidylserine was much lower than on the activity elicited by phosphatidylserine alone, thereby demonstrating the Ca2+ sensitivity of protamine phosphorylation.

Animals↗
PubMed1987

Effects of an erbium: YAG laser on ocular structures.

We evaluated the effects of the erbium:YAG laser (2.9 micron wavelength) on ocular structures. Energy was successfully transmitted through a fiberoptic bundle for intraocular and extraocular applications. The wavelength was strongly absorbed by ocular tissues, producing ablations with minimal thermal damage. Our results indicated that the erbium:YAG laser may have potential uses as a photoablative tool to reshape the corneal surface and as a surgical knife.

Animals↗