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Biomedical subjects

Y Hotta

Publications and source records attributed to Y Hotta.

At least 199 records · Page 11Linked to original sources
PubMed1987

[Studies on cardiac ingredients of plants (IV). Effect of reduced proscillaridins on guinea-pig hearts].

Five hydrogenated proscillaridins (bufa-4,20-dienolide (PH21), bufa-4,20 (22)-dienolide (PH22), 20R-bufa-4-enolide (PH4-R), 20S-bufa-4-enolide (PH4-S), chola-4-enoate (PH4-E) ) were prepared semi-synthetically, and their pharmacological effect was studied using guinea pigs. The positive inotropic effect (PIE) was examined in papillary muscles isolated from guinea-pig hearts. These compounds produced PIE, dose-dependently; the Dose-PIE curve was characterized by a faster PIE development than that by the parent compound proscillaridin (PS). The concentrations at which half maximum PIE just developed (pD2) were as follows: PS, 7.4; PH22, 6.2; PH21, 5.8; PH4-R, 5.3; PH4-E, 5.0; and PH4-S, 4.9. The time required to the half maximum effect (T50) at a given concentration of pD2 was measured in min: PS, 33; PH4-E, 22; PH22, 15; PH21, 7; PH4-S, 7; and PH4-R, 2. The speeds of inotropy of these compounds depended on the position of lactone ring reduction, though they have the same lipophilicity (Rm). Concentration-PIE curves of reduced PS-compounds were characterized by a decrease in potency and an increase in efficacy. PH21 and PH4-R produced PIE over wider range of concentrations than those of the other compounds. When PH21 at the dose of 11.9 mg/kg, an equivalent dose of 4.4 times the pD2 values, was administrated intravenously by bolus injection into guinea pigs, no arrhythmias were observed on the ECG.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

High resolution G-banding analysis in aniridia.

The authors investigated eight cases of aniridia by high resolution G-banding analysis (750 bands). A deletion of the short arm of chromosome 11 was found in two cases. One of these involved a three months old boy who was suspected of having Wilms' tumor. After elaborate investigations by pediatric surgeons, Wilms' tumor was found in his left kidney and was successfully removed in its early stage. These results suggest that high resolution G-banding analysis should be performed in all cases of infantile aniridia as a screening test for early detection of Wilms' tumor.

Child, Preschool↗
PubMed1987

[Combined clinical effect of amikacin and cefoxitin in patients with severe infections complicated by hematological diseases].

A clinical investigation was made on the concurrent use of amikacin (AMK) and cefoxitin (CFX) against complicated infections with hematological disorders. The results obtained were summarized as follows: Eleven patients were treated with AMK and CFX. Clinical responses were excellent in 2 (18%), good in 4 (36%), fair in 1 (9%), and poor in 4 (36%), with an efficacy rate of 64%. No significant side effects requiring cessation of the treatment were observed.

Adolescent↗
PubMed1986

Germline transformation with Drosophila mutant actin genes induces constitutive expression of heat shock genes.

Two Drosophila mutants KM75 and HH5, which are mutated in the act88F actin gene specific for the indirect flight muscles (IFM), synthesize heat shock proteins (hsps) constitutively in a tissue-specific manner. We have introduced cloned mutant act88F genes into a strain containing the wild-type act88F allele by P-element-mediated transformation. Flies transformed with a 4.05 kb KM75 act88F gene fragment encoding the p42 actin variant express both p42 and hsps specifically in the IFM. Using normal/mutant chimeric genes, the mutation sites of KM75 and HH5 were mapped within the sequence encoding the last 72 amino acids of actin. An in vitro mutated gene encoding a protein that lacks the 72 carboxy-terminal amino acids also induces constitutive hsp synthesis.

Actins↗
PubMed1986

Molecular characterization of mutant actin genes which induce heat-shock proteins in Drosophila flight muscles.

Heat-shock proteins (hsps) are constitutively induced by the mutant actins in the Drosophila indirect flight muscles (IFM). We compared primary structures of the mutant actin genes (KM75 and HH5) which induce hsps and of the non-inducing alleles (KM129 and KM88). The KM75 actin has lost 20 amino acids at the C-terminus. The HH5 actin has only one amino acid substitution, from Gly-336 to Ser. In KM129, the C-terminal part of actin is replaced by novel amino acids. KM88 is a null allele, with an amber mutation early in the coding region of the mutated actin gene. Although all of the KM75, HH5 and KM129 actins have defects near the C-terminus, only hsp-inducing mutant actins cause enlargement of the IFM nuclei as well as a disruption of myofibrils even in the presence of two copies of the normal genes. We further consider the underlying mechanisms linking these features of the hsp-inducing alleles.

Journal Article↗
PubMed1986

Determination of endotoxin in injectable antibiotic preparations by the chromogenic assay method using a Limulus reagent (Tachypleus hemocyte lysate) and a chromogenic substrate.

The effects of 50 antibiotics on the detection and determination of bacterial endotoxins by the chromogenic method using a Limulus reagent (Tachypleus hemocyte lysate) and a chromogenic substrate of p-nitroaniline derivatives were tested, and the antibiotic concentration for 50% inhibition of the chromogenic reaction in the presence of 0.5 ng of endotoxin (Escherichia coli 0111:B4) per ml was estimated. All the antibiotic preparations were depyrogenized by ultrafiltration treatment before they were subjected to the test. The reaction was conducted in the presence of a high concentration (0.5 M) of Tris buffer to constantly maintain the pH of the reaction mixture, and liberated p-nitroaniline was determined by high-pressure liquid chromatography. Several aminoglycosides (amikacin, bekanamycin, kanamycin, and streptomycin sulfate), bleomycin hydrochloride, and fosfomycin disodium showed no inhibition of the reaction up to 20 mg/ml. However, other antibiotics, including penicillins, cephalosporins, macrolides, and tetracyclines, inhibited the reaction concentration dependently. Polymyxin B sulfate was the most potent inhibitor, with less than 8 micrograms/ml for 50% inhibition. It was concluded that the chromogenic method can be applied to the detection and determination of endotoxin in most of the antibiotic preparations. An application of this method to carbenicillin disodium preparations was exemplified.

Aniline Compounds↗
PubMed1986

General recombination in meiosis.

The meiotic events of homologous pairing and chiasma formation are apparently related to a number of meiotic processes. These include a delayed replication of small portion of genome (zygoDNA). L-protein, present transitionally in meiotic S-phase and leptotene, can bind to the specific sequences of zygo DNAs to form a nick and selectively suppress their replication until zygotene. Other meiosis specific proteins (R-protein, U-protein, rec A-like protein (m-rec) probably related with pairing and recombination but none of these, either alone or combination, is capable of inducing recombination in vitro. We have isolated proteins from meiotic and somatic cells that are capable of recombining two DNA plasmids in vitro. They have been designated m-recombinase and s-recombinase, respectively. m-recombinase appears during meiotic prophase with or without chiasma-formation, suggesting that regulation of meiotic recombination depends, not on the formation of appropriate enzymes but on rendering the enzymes effective by altering chromatin-structure. s-recombinase activity seems to be related to cell division and/or cell differentiation. The assay system used here for necessary recombination may be applicable to various situations.

Animals↗
PubMed1985

A genetic study of inositol trisphosphate involvement in phototransduction using Drosophila mutants.

Phosphatidylinositol 4,5-bisphosphate phosphodiesterase activity was found to be almost absent in the compound eyes of Drosophila visual mutant, norpA (no receptor potentials A). We compared the enzyme activities among independently isolated norpA alleles, each having a different degree of the vision defect. A close correlation was found between the size of receptor potentials (electroretinogram), phototactic behavior and the enzyme activity. The correlation exists not only among alleles, but also in a single, temperature-dependent allele under different temperature; the enzyme activity of flies kept at 18 degrees C (phototactic) was about five times higher than that of the ones kept at 28 degrees C (blind). These results suggest that hydrolysis of phosphatidylinositol 4,5-bisphosphate is involved in phototransduction process in Drosophila eyes.

Alleles↗
PubMed1985

Actin gene mutations in Drosophila; heat shock activation in the indirect flight muscles.

We have identified four mutations affecting the actin III isoform in the indirect flight muscles (IFM) of Drosophila. One mutation does not produce any protein product, and three direct the synthesis of electrophoretic variants of actin. Complementation tests and recombination mapping indicate that all mutations are alleles of an actin gene at chromosomal band 88F (act88F gene). The effect of these mutations is restricted to the IFM. We conclude that the act88F gene is expressed only in the IFM to encode actin III, which is its major isoform. In two of the actin mutants, heat shock proteins are constitutively expressed in the IFM. Genetic evidence strongly suggest that this anomaly is primarily caused by the mutations in the act88F structural gene.

Journal Article↗
PubMed1985

General recombination mechanisms in extracts of meiotic cells.

RecA-like proteins have been purified from somatic and meiotic cells of mouse and lily. The rec proteins have been designated "s-rec" and "m-rec" to indicate their respective tissues of origin. The two proteins differ in molecular weight and in their response to temperature, the latter being consistent with the optimal temperature for physiological function of their tissues of origin. There is a major increase in m-rec protein with the entry of cells into meiosis, the peak of activity being early pachytene. Extracts of the cells and also those of yeast (Saccharomyces cerevisiae) have been prepared that have the capacity to catalyze homologous recombination. These extracts behave similarly to the m-rec proteins upon entry of cells into meiosis. Yeast transferred to sporulation medium displays a 100-fold increase in the recombination activity of the extract at about the time of entry into meiosis. The occurrence of peak levels of m-rec and recombination activity in extracts from cells in early pachytene points strongly to that stage as the time at which the enzymatic phase of recombination occurs.

Animals↗
PubMed1985

Meiosis-specific transcripts of a DNA component replicated during chromosome pairing: homology across the phylogenetic spectrum.

In meiotic cells of Lilium, a group of single or low copy number DNA sequences that constitute about 0.1-0.2% of the genome do not replicate during the premeiotic S-phase but do so at zygotene in coordination with chromosome pairing. An appreciable fraction of these sequences has now been found to be transcribed into poly(A)+ RNA when chromosomes initiate the pairing process. This "zygRNA" has not been detected in nonmeiotic tissues. Even within the meiocytes, zygRNA is not detectable prior to leptotene or beyond midpachytene. S1 nuclease digestion of mouse spermatocyte nuclei selectively released zygDNA, which hybridizes with lily zygRNA. zygRNA has not been detected in mouse somatic tissues. The profile of zygRNA formation and disappearance in mouse spermatocytes is very similar to that of zygRNA in lily meiocytes.

Animals↗
PubMed1985

Absence of phosphatidylinositol phosphodiesterase in the head of a Drosophila visual mutant, norpA (no receptor potential A).

Phosphatidylinositol phosphodiesterase activity was found to be entirely absent in the head of the Drosophila visual mutant, norpA. It was also demonstrated that the enzyme activity was highly concentrated in the retinular cells of a normal head. Furthermore, the enzyme was revealed to be in a membrane bound form. In view of the present results and our previous work on the reduction of diacylglycerol kinase activity in the norpA mutant, phosphatidylinositol metabolism may play an important role in the generation of photoreceptor potentials.

Animals↗