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Biomedical subjects

K Murakami

Publications and source records attributed to K Murakami.

At least 1,099 records · Page 61Linked to original sources
PubMed1985

[Biomicroscopic observation of macular breaks].

Ninety-five eyes from 90 patients with macular breaks were studied biomicroscopically using the E1 Bayadi-Kajiura preset lens. Retinal detachments due to macular breaks were present in 14 of the eyes. The prevalence of posterior vitreous detachments (PVD) was 44% in idiopathic senile macular breaks (66 eyes), 78% in highly myopic macular breaks (9 eyes), and 95% in secondary macular breaks (20 eyes). Opercula, indicated the presence of vitreous traction, were found in 48% of the senile cases, in 22% of high myopes, and in 20% of secondary cases. Most of opercula were seen in eyes with no PVD or partial PVD. In 4 eyes without high myopia, vitreous traction at the edges of macular breaks resulted in retinal detachment.

Adult↗
PubMed1985

[Cerebellar degeneration in chronic alcoholism: with special reference to an autopsied case showing the restricted form of cerebellar cortical degeneration (Victor)].

The brains of 8 patients with chronic alcoholism were neuropathologically examined. The findings obtained in the cerebellum of case 1 (male, aged 52) were in agreement with the restricted form of cerebellar cortical degeneration which was described by Victor et al (1958). The clinicopathological report on the cerebellar degeneration of this type was very rare in Japan. The cerebellar changes were more pronounced in the anterior vermis than in the posterior vermis and hemisphere. Furthermore, some old lesions of Wernicke's encephalopathy were found in this brain. 7 other cases showed very mild cerebellar degeneration. Partial loss of Purkinje cells was found near the tops of cerebellar folia. But their distribution and intensity had no individual variation and there was no tendency that the anterior vermis was more affected. This fact suggests that the alcoholic cerebellar degeneration may have some other cause than the direct toxic effect of ethylalcohol or its metabolites. The etiology of this disease was discussed with reference to thiamine deficiency and mal-nutrition.

Adult↗
PubMed1985

Histological studies on the inner surfaces of the articular cavities of human temporomandibular joints with special reference to arthroscopic observations.

Histological findings relating to the arthroscopic anatomical features in the inner surfaces of human temporomandibular joints are described. Articular surface covering the bony surface is histologically fibrocartilage. The articular surface of the articular disk is histologically composed mainly of tightly packed collagen fibers, but partly of fibrocartilage which is considered to be developed in the area where presumably maximal stress is given during the joint movement. The synovial membrane consist of 2 layers. The superficial one is the lining cell layer formed by single or multiple rows of cells with from ovoid to cuboidal shapes. The deep one is a capillary rich loose connective tissue layer. The present study suggests that arthroscopic views well reflect histological features of the inner wall of the articular cavity of the temporomandibular joint.

Adult↗
PubMed1984

Kinetics of the inhibition by naphtholsulfonate compounds of AMP deaminase from chicken erythrocytes.

The effect of a variety of naphthalene sulfonate compounds on the chicken erythrocyte AMP deaminase (AMP aminohydrolase, EC 3.5.4.6) reaction was analyzed kinetically. Of the naphthalene sulfonate derivatives tested, the compounds with hydroxyl, sulfonate and nitrogen groups such as amino, anilino or azo groups showed an inhibitory effect. The cooperative effect of AMP, analyzed in terms of Hill coefficient, was increased from about 2 to 4 and the maximal velocity was unchanged with the addition of these compounds, suggesting the ligands as an allosteric inhibitor of the enzyme. The inhibition of AMP deaminase by naphtholsulfonate compounds can be qualitatively and quantitatively accounted for by the Monod-Wyman-Changeux model. Theoretical curves yield a satisfactory fit of all experimental saturation and inhibition curves, assuming four binding sites for AMP and the inhibitor, and various KT(I) values. The structure-activity analysis of the interaction of the naphtholsulfonate compounds with AMP deaminase has demonstrated that the affinity of the enzyme for naphtholsulfonates as the inhibitors is correlated with electronic properties of the nitrogen atoms attached to naphthalene moiety: the delocalization of lone electron pair on nitrogen through naphtholsulfonate group makes the compound less basic, resulting in more tight binding of the ligand to the enzyme. Introduction of hydrophobic group to naphtholsulfonate moiety increases the binding affinity for the enzyme, and of the inhibition. These results suggest the location of hydrophobic regions as the allosteric inhibitory sites of the enzyme for the binding of naphtholsulfonate compounds.

AMP Deaminase↗
PubMed1984

Pseudouridylic modification of a 6S RNA transcribed in vitro from highly repetitive and transcribable (Hirt) sequences of salmon total DNA.

Salmon total DNA was transcribed in a HeLa cell extract, and it was found that a distinct 6S RNA is transcribed by RNA polymerase III. By analogy with a 6S RNA transcribed from mouse total DNA in vitro, which we demonstrated to be the transcripts from type 2 Alu family (Sakamoto et al. (1984) Mol Gen Genet 194:1-6), the genes for the 6S RNA in the salmon genome are presumed to be reiterated in at least 10(4)-10(5) copies and to be dispersed among the genome. A fingerprint analysis showed that the nucleotide sequences of the genes for the 6S RNA are extensively conserved. Furthermore, we demonstrated that at least two positions in the 6S RNA are modified in vitro to pseudouridylic acid. The pseudouridylic acid residues are located in specific oligonucleotides and each of the modified nucleotides amounts to 0.5 to 1.0 mol per mol of RNA. The relationship between salmon highly repetitive and transcribable (Hirt) sequences and rodent type 2 Alu family, and the significance of the pseudouridylic modification in relation to the functional role of these sequences are discussed.

Animals↗
PubMed1984

Structure of angiotensin II-binding site probed with diaminoalkanes.

The nature of the hormone-binding site of detergent-solubilized angiotensin II receptor from the bovine adrenal cortex has been characterized using diaminoalkanes. Their affinity for the hormone-binding site showed a dramatic alteration depending on their chain length; at the hexamethylene stage, a maximum and competitive inhibition was observed. These results indicate that the angiotensin II receptors have a definite hydrophobic binding groove limbed with diagonally located two negative charges, and those hydrophobic and electrostatic forces may play an important role in the proper register between the receptor and hormone.

Adrenal Cortex↗
PubMed1984

An improved method for determination of active and total renin concentration in human plasma using an excess of sheep substrate.

A method for measurement of renin concentration (PRC) in human plasma has been developed and validated experimentally and theoretically. Like most of the previous methods, the present method is based on a radioimmunoassay of angiotensin I generated during incubation of plasma with an excess of renin substrate. In the present study we used, as the substrate, sheep angiotensinogen partially purified from anephric sheep plasma by ammonium sulfate fractionation and pepstatin-aminohexyl-agarose chromatography. The advantage of using sheep substrate is that it has an exceptionally high affinity for human renin. The partially purified substrate, which contained no detectable renin activity, improved the sensitivity, allowing quantification of renin in low-renin plasma. Possible interfering influences of plasma proteins on the radioimmunoassay were eliminated by the introduction of a simple deproteinization step. For determination of total renin concentration (TRC), inactive renin was activated by exposing plasma to low pH or trypsin. Normal values of PRC and TRC after careful selection of assay conditions were 2.9 +/- 0.4 and 33.9 +/- 6.1 ng angiotensin I X ml-1 X h-1, respectively. As an illustrative example of usefulness of the assay, PRC determination of a patient with a ectopic renin-secreting tumor is presented.

Adult↗
PubMed1984

The inhibitory effect of X537A on vascular and intestinal smooth muscle contraction.

The effects of X537A (Lasalocid) on contractions induced in vascular and intestinal smooth muscles were examined. High K-induced sustained contractions were inhibited by X537A with an IC50 of 2.8 X 10(-6) M in rabbit aorta and 8.8 X 10(-8) M in guinea-pig Taenia coli. Changing the Ca concentration in the medium did not modify the effect of X537A. X537A also inhibited the noradrenaline-induced contraction in aorta (IC50 = 7.0 X 10(-8) M). In a solution without added glucose, the inhibitory effect of X537A on the K-induced contraction in aorta was augmented (IC50 = 1.5 X 10(-8) M). Under hypoxic conditions, the inhibitory effects of X537A on the noradrenaline-induced contractions in aorta and on the K-induced contraction in T. coli were decreased (IC50 greater than 10(-5) M and 3.2 X 10(-6) M, respectively). X537A inhibited the K-induced increase in cellular 45Ca content in aorta measured by a modified lanthanum method. However, the IC50 for 45Ca uptake (6.6 X 10(-7) M) was lower than that for K-induced contraction. In both tissues, X537A decreased the ATP content. Oxygen consumption of rat liver mitochondria was inhibited by X537A. From these results, it is concluded that the inhibitory effect of X537A on the noradrenaline-induced contraction in aorta and the K-induced contraction in T. coli, but not the K-induced contractions in aorta, may be due to the inhibition of aerobic metabolism.

Adenosine Triphosphate↗