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Biomedical subjects

Y Mikami

Publications and source records attributed to Y Mikami.

At least 271 records · Page 15Linked to original sources
PubMed1986

Comparison of selectivity of LDL removal by double filtration and dextran-sulfate cellulose column plasmapheresis.

The possibility of selective removal of VLDL, IDL and LDL by double filtration (DF) and dextran-sulfate cellulose (DSC) column plasmapheresis was investigated in hypercholesterolemia. Two and a half liters of plasma were treated. Sixty six percent of TC and 68% of LDL-C were removed by DF plasmapheresis. The removal rate of HDL-C was 50% which was significantly lower than that of LDL-C. The removal rate of apoprotein A-I and A-II was also significantly lower than that of apoprotein B. Sixty percent of LDL-C and 61% of apoprotein B were removed by DSC column plasmapheresis while the decrease of HDL-C, apoprotein A-I and A-II was minimal. Therefore, DSC column plasmapheresis could remove atherogenic lipoproteins more selectively than DF plasmapheresis.

Adult↗
PubMed1986

Isolation and structural elucidation of new saframycins Y3, Yd-1, Yd-2, Ad-1, Y2b and Y2b-d.

A new series of saframycins Y3, Yd-1, Yd-2, Ad-1, Y2b and Y2b-d was produced by directed biosynthesis employing resting cells of saframycin producer, Streptomyces lavendulae No. 314. Their structures were determined by comparison with the spectral data of UV, IR, and 1H and 13C NMR of saframycin A, whose structure has already been established. Saframycin Y3 is 25-deoxy-25-aminosaframycin A, while saframycin Yd-1 is 26-homosaframycin Y3, and saframycin Y2b is a dimer of saframycin Y3. Saframycin Ad-1 is 26-homosaframycin A. Saframycin Yd-2 is 26-demethylsaframycin Y3, and saframycin Y2b-d is a dimer of saframycin Yd-1.

Anti-Bacterial Agents↗
PubMed1986

Antitumor activity of new semisynthetic saframycin derivatives.

Saframycins Yd-1 and Y3, which have an amino functional group in the side chain, were recently obtained by a directed biosynthesis. Twenty-eight side chain-modified chemical derivatives were prepared from these saframycins, and their in vitro and in vivo antitumor activities were studied. Among these new derivatives, three saframycins, namely, two N-acyl derivatives, pivaloyl- and n-caproylsaframycin Y3, and one water-soluble type, saframycin Yd-1.HCl, were found to show marked antitumor activity against L1210 mouse leukemia cells. Further studies of these saframycin derivatives using B16-F10 melanoma and Lewis lung carcinoma indicated that all three saframycins are also active against B16-F10 melanoma; saframycin Yd-1.HCl showed the greatest prolongation of survival time. Marked inhibition of spontaneous metastasis of Lewis lung carcinoma was observed in mice treated with these new derivatives. Structure-activity relationships among these semisynthetic saframycins are discussed.

Animals↗
PubMed1986

Lymphocutaneous nocardiosis caused by Nocardia asteroides. Case report and literature review.

A 22-year-old man developed erythematous nodules and an ulcer mimicking sporotrichosis on his right hand and forearm, which was subsequently diagnosed as lymphocutaneous nocardiosis caused by Nocardia asteroides. To our knowledge, 21 cases of lymphocutaneous nocardiosis have been reported, with the majority of those cases, except for a few that remain uncertain, being due to Nocardia brasiliensis. The case reported herein, the first known definitive case caused by N asteroides (to our knowledge), showed a more chronic course and less inflammatory manifestation compared with that caused by N brasiliensis. This is probably because N brasiliensis has a stronger virulence than N asteroides.

Adult↗
PubMed1985

[Insulin, glucagon and growth hormone responses during glucose, arginine and insulin tolerance tests in children with hyperthyroidism].

There are many reports of glucose intolerance in adult patients with hyperthyroidism but few reports of glucose intolerance in hyperthyroid children. In this study, we measured plasma levels of glucose, insulin, glucagon and growth hormone in hyperthyroid children and control subjects by the use of three kinds of tolerance tests: an oral glucose tolerance test, an arginine tolerance test and an insulin tolerance test. In the oral glucose tolerance test, mean fasting glucose levels (79.6 +/- 1.4 mg/dl) rose to maximum levels (157.3 +/- 4.3 mg/dl) at 30 min in hyperthyroid children which were significantly higher than the levels in control subjects (p less than 0.01). The maximum levels of glucose fell slowly and returned to fasting levels at 180 min. In this test, plasma insulin levels increased from basal levels (12.7 +/- 1.9 microU/ml) to maximum levels (120.8 +/- 22.1 microU/ml) at 30 min in the prepubertal age group of hyperthyroidism. On the other hand, in the pubertal age group of hyperthyroidism, maximum levels of insulin were observed at 60 min, but not at 30 min. These maximum levels of insulin of both hyperthyroid age groups were significantly higher than those in the control subjects (p less than 0.05, p less than 0.01 respectively). There was no difference in insulin-glucose ratio at 30 min (delta IRI/delta BG) and insulinogenic index (I.I.) at 0 to 60 min between these two groups of hyperthyroid children and control subjects. However, I.I. at 0 to 120 min and 0 to 180 min decreased significantly in the pubertal age group of hyperthyroidism as compared with those in the control group (p less than 0.05, p less than 0.02 respectively). In the oral glucose tolerance test, plasma glucagon levels decreased from basal levels (74.1 +/- 4.3 pg/ml) to minimum levels (36.4 +/- 4.7 pg/ml) at 90 min in hyperthyroidism, which were significantly lower than those in the controls (p less than 0.05). However, there was no difference in -epsilon delta IRG/epsilon delta BG (cumulative glucagon response/cumulative glucose response) between the subjects with hyperthyroidism and the controls. On the other hand, lower responses of blood glucose, insulin, glucagon and growth hormone to arginine were observed in subjects with hyperthyroidism than in the controls. Moreover in the insulin tolerance test, there was no difference in glucagon and growth hormone response between the subjects with hyperthyroidism and the controls. Thus our conclusions are as follows: A marked increase in blood glucose after oral glucose load was observed in spite of normal insulin-glucose ratio in hyperthyroid children, suggesting the existence of peripheral insulin resistance.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1985

Biosynthetic studies on saframycin A, a quinone antitumor antibiotic produced by Streptomyces lavendulae.

The biosynthesis of saframycin A, a heterocyclic quinone antitumor antibiotic isolated from Streptomyces lavendulae 314, was studied by feeding experiments with 14C and 13C precursors. Highly increased production of saframycin A and prolongation of the maximum production period of saframycin A were attained by constant pH control of the culture and by addition of chloramphenicol to the culture. The biosynthetic origin of the quinone skeleton common to the saframycin group was confirmed to be two tyrosine molecules which condense to generate the basic ring system of saframycin A. Feeding experiments with [1-13C]tyrosine showed specific labeling of C-11 and C-21 carbons of saframycin A, and the enrichment of the carbons was 40-fold over natural abundance. Two O- and two C-methyl and one N-methyl carbons arose directly from methionine, and alanine and glycine were the precursors for the pyruvoyl amide side chain of saframycin A.

Amino Acids↗
PubMed1985

Directed biosynthesis of new saframycin derivatives with resting cells of Streptomyces lavendulae.

Saframycin A is an antitumor antibiotic produced by Streptomyces lavendulae 314 which falls into the category of the N-heterocyclic quinone group. Biosynthetically the quinone ring is derived from two tyrosine molecules which condense to generate the basic ring system of saframycin A. The side chain also has been found to derive from two amino acids, i.e., glycine and alanine. Supplementation by various amino acid analogs of the side chain produced three new saframycin derivatives with a replaced side chain. These three saframycins, designated Yd-1, Yd-2, and Y3, contained 2-amino-n-butyric acid, glycine, and alanine residues, respectively. in place of the normal N-terminal pyruvic acid in the side chain of saframycin A. Feeding experiments with 13C-labeled dipeptide indicated that the amino acids are probably incorporated in the side chain as a dipeptide unit. It was also found that saframycin A is produced from saframycin Y3 by an enzymatic deamination reaction. Based on these results, saframycin biosynthesis in S. lavendulae is discussed.

Amino Acids↗
PubMed1984

Studies on defense mechanisms against Candida albicans infection in congenitally athymic nude (nu/nu) mice.

The defense mechanisms against Candida albicans infection were studied by using a mouse thigh lesion model in congenitally athymic nude (nu/nu) mice and their normal littermates (nu/+). Nu/nu mice were more resistant to C. albicans infection than nu/+ mice judging from the course of the thigh lesion, the results of CFUs (colony-forming units) of C. albicans in the lesion, and histopathological observations. Histopathological and serological studies revealed that granulocytic cellular infiltration was predominant, and there were few indications of development of cell-mediated immunity to protect Candida infection in Candida-infected nu/nu and nu/+ mice. These results confirmed that lower susceptibility of nu/nu mice to C. albicans infection as compared to nu/+ mice was due to accelerated non-specific defense mechanisms in nu/nu mice, and that cell-mediated or humoral immunity played a minor role in the defense against Candida infection in this experimental model. Furthermore, treatment with high titer of rabbit anti-C. albicans serum was effective to control the number of Candida cells in thigh lesions of BALB/c mice. Above experimental results seem to clearly indicate the great variability of defense manifestation according to the experimental model exployed.

Animals↗
PubMed1984

The effect of heating on Y-chromosome detection.

The effect of heating on Y-chromosome detection was investigated. Heat-treated blood was divided into four groups according to the hemolysis pattern obtained by the coil planet centrifuge system. A significant difference between the Y-positive nuclei of males and females was observed up to group III of the hemolysis pattern, and it was possible to determine the sex of the blood donor in spite of karyolysis and degeneration of blood components. However, sex determination of blood in group IV, indicating complete hemolysis, was impossible because of overlapping between male and female Y-chromosome counts. Practical application of this sex determination method was successful even with severely burned cadavers. However, it was suggested that putrefaction together with heat damage made the identification nearly impossible.

Blood Chemical Analysis↗
PubMed1984

Prolactin response to thyrotropin-releasing hormone in children with gynecomastia, premature thelarche and idiopathic precocious puberty.

Plasma prolactin (PRL) response to synthetic thyrotropin-releasing hormone (TRH) was studied in six patients with pubertal gynecomastia, five patients with premature thelarche and nine female patients with idiopathic precocious puberty. The basal concentration of plasma PRL was higher (p less than 0.01) in pubertal gynecomastia as compared to control, while baseline plasma PRL levels in premature thelarche and idiopathic precocious puberty were similar to those in controls. Plasma PRL level after TRH in patients with pubertal gynecomastia was higher (p less than 0.01) than that in control, while plasma PRL responses to TRH in idiopathic precocious puberty and premature thelarche were comparable to those controls. The TRH-induced PRL release was more enhanced during treatment with cyproterone acetate (CA) than before CA therapy in four of five patients with idiopathic precocious puberty. These data suggest that the enhanced release of PRL may, at least in part, contribute to breast enlargement in pubertal gynecomastia and that seen in idiopathic precocious puberty and premature thelarche may not depend on the PRL secretion. The prolonged administration of CA enhances the PRL responsiveness to TRH.

Adolescent↗