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Biomedical subjects

Y Kano

Publications and source records attributed to Y Kano.

At least 253 records · Page 14Linked to original sources
PubMed1986

Site-specific chromosomal rearrangements induced in human diploid cells by x-irradiation.

A total of 130 stable, two-break reciprocal translocations were scored in G-banded karyotypes prepared from 375 metaphase spreads from a strain of human diploid fibroblasts irradiated with 400 or 600 rads and analyzed 1-20 mean population doublings later. The chromosomal location of each of the 260 breakpoints was mapped. The sites of 121 chromosomal breaks and deletions in the first postirradiation mitosis were also scored. Unlike the random distribution of these latter events, the translocation breakpoints showed not only a nonrandom distribution among chromosomes but also the existence of specific sites within chromosomes that were more frequently involved in translocations. The most notable finding was a marked excess of translocations involving the short arm of chromosome 1, in particular, band 1p22. The specific types of translocations were random, although the breakpoints were not. Eight of the 12 most frequently involved chromosomal sites were regions in which fragile sites have been mapped in human lymphocytes.

Cells, Cultured↗
PubMed1986

Developmental changes in the inner surface structure of the bovine large intestine.

The developmental pattern of the bovine fetal large intestine was studied with particular reference to the appearance and decline of the intestinal villi during the fetal period. In the bovine large intestine, the first rudimentary villus and goblet cells were seen in the rectum in a fetus estimated to be 3 months old. By 5-6 months, the goblet cells, absorptive cells in the intestinal crypts, and vacuolated cells in the villi were present along all segments of the large intestine. By 8-9 months, the villi have disappeared from the colon and rectum, epithelial cells no longer contain vacuoles, and absorptive and goblet cell populations are emerging from the crypts. These histological results suggest that development in the bovine large intestine follows a recto-cecal gradient and the most distinct turning point during the fetal period is the first disappearance of fetal villi in the rectum of fetuses estimated to be 7 months old. After this stage, the mucous membrane of the colon and rectum matured rapidly before birth. In contrast, the cecum may seem to require further development in perinatal life.

Animals↗
PubMed1986

Superior cervical ganglionectomy prevents gonadal regression and increased plasma prolactin concentrations induced by long days in goats.

The effects of the abolition of the diurnal change in melatonin secretion on the photoperiodic response of the gonadal axis and prolactin secretion to long days were examined in female goats. Female Saanen goats, reared under short-day conditions (8 h light: 16 h darkness; lights on at 05.00 h) at 22 +/- 2 degrees C for 5 months, were bilaterally superior cervical ganglionectomized (SCGX). One month after surgery, both SCGX and intact control goats were divided into two groups. Animals in group 1 were maintained under short days and those in group 2 moved to long days (16 h light: 8 h darkness; lights on at 05.00 h). In group 1, both SCGX and intact goats ovulated periodically and basal plasma prolactin levels were maintained throughout the day. In intact controls, exposure to long days suppressed ovulation and increased prolactin secretion for the first 150-200 days of exposure. The animals became photorefractory after this time; ovulation recurred and prolactin secretion returned to basal levels. Superior cervical ganglionectomy abolished or weakened the suppression of gonadal function and eliminated the increase in prolactin secretion induced by exposure to long days in the intact controls. These results suggest that the pattern of melatonin secretion under long days is necessary to induce the photoperiodic response of gonadal function and prolactin secretion to long days and that, under natural conditions, melatonin regulates the seasonal changes in gonadal function and prolactin secretion by mediating the effect of long days.

Animals↗
PubMed1986

Defect of the first-phase insulin secretion to glucose stimulation in the perfused pancreas of the nonobese diabetic (NOD) mouse.

To investigate the development of impaired insulin secretion in type I diabetes mellitus, the pancreata of ICR and NOD mice (10-50 wk of age) were perfused. According to insulin responses to 30 mM glucose and to 19 mM arginine, we classified the NOD mice into four groups: those having normal insulin secretion to glucose and to arginine similar to that of control ICR mice (group 1); those with a defect in the first-phase insulin secretion to glucose stimulation but with almost normal insulin secretion to arginine, total insulin release to glucose being significantly smaller than that of group 1 (group 2); those having only a small insulin response to either stimulus, but a fasting plasma glucose level still within the normal range (group 3); and those being overtly diabetic, showing no insulin response to either stimulus (group 4). The severity of insulitis and insulin concentration of the pancreas in each group of NOD mice was well correlated with the insulin release from the perfused pancreas. These results indicate that the initial sign of B-cell damage in NOD mice is a defect of the first phase of glucose-induced insulin secretion, which is followed by a total loss of ability to respond to glucose or arginine stimulation.

Animals↗
PubMed1986

Folate requirements of methotrexate-resistant human acute lymphoblastic leukemia cell lines.

We studied the folate requirements of a human acute lymphoblastic leukemia cell line, MOLT-3, and methotrexate (MTX)-resistant sublines established in vitro. The requirement of pteroylglutamate (PGA) for optimal cell growth was different for each cell line. With increasing MTX resistance, there was progressive increase in PGA requirements, moving the PGA concentration-cell growth curve (dose-response curve) 1 log order of magnitude to the right. The increases in the requirement of 5-methyltetrahydrofolate (5-methyl-THF) by the resistant sublines were more pronounced than PGA requirement, moving the dose-response curve nearly 3 log orders in magnitude to the right. The concentrations in vitro of 5-methyl-THF required for optimal growth of the MTX-resistant sublines far exceeded the normal serum 5-methyl-THF concentrations known in humans. These observations show that MTX-resistant cell established in vitro in culture media containing PGA instead of 5-methyl-THF, a physiological folate, cannot be expected to grow in vivo. The collateral sensitivity of transport-impaired MTX-resistant sublines to 2,4-diamino-5-methyl-6-[(3',4',5'- trimethoxyanilino) methyl] quinazoline (trimetrexate, TMQ) was negated in the absence of PGA. With the addition of 5-methyl-THF, the parent cells became more resistant than the transport-impaired sublines to TMQ These data indicate that the collateral sensitivity of MTX resistant cells to the substituted 2,4-diaminoquinazoline is due to functional folate deficiency by virtue of the impaired transport of folate.

Biological Transport↗
PubMed1985

Mechanisms of human cell neoplastic transformation: relationship of specific abnormal clone formation to prolonged lifespan in X-irradiated human diploid fibroblasts.

A total of 9 control and 46 X-irradiated human fibroblast cultures were followed throughout their lifespan in vitro; G-banded karyotypes were examined at regular intervals. The lifespan (mean population doublings) of irradiated cultures was slightly but significantly prolonged over that of controls. None of the cultures developed any changes in cell morphology characteristic of neoplastic transformation. A number of abnormal clones containing marker chromosomes emerged in the irradiated cultures. Most of these senesced early, but 2 clones were associated with a considerably increased lifespan. One of these had a deletion in the short arm of chromosome I (p22, p32), and the other had 2 specific translocations involving chromosome 22, t(1;22)(q25,q12) and t(6;22)(p22,q11). We hypothesize that the emergence of an abnormal clone with translocations in the vicinity of critical oncogenes may be associated with prolongation of lifespan and the induction of immortalization in human diploid cells, an event independent of the acquisition of other characteristics of the transformed phenotype.

Cell Survival↗
PubMed1985

Abnormal fibroblast aging and DNA replication in the Werner syndrome.

Cell and DNA replicative potentials were studied in 10 strains of skin fibroblasts from unrelated patients with the Werner syndrome (WS) and in a progeric CRL 1277 strain. The lifespans of all WS strains and of CRL 1277 cells are greatly abbreviated in vitro, due to large fractions of non-cycling cells and the basic process of progressive clonal attenuation during Phase II. In some WS strains, the population-doubling rate per day and the cloning efficiency fluctuated concurrently in random fashion during the cellular aging process, indicating alternating successions of adaptively well and poorly growing clones, probably resulting from various chromosome translocations. No detectable defect in excision repair was found in WS or CRL 1277 cells. However, the rate of increase in the molecular weight of pulse-chased DNA involving overall rates of chain elongation and replicon fusion was retarded in WS and CRL 1277 cells. Also, pulse-labelled DNA in WS fibroblasts was less enriched in the nuclear matrix and was more slowly chased out than in normal cells. These results led us to postulate a misfiring or delayed initiation due to the sticky attachment of replicating DNA to the nuclear matrix in the replisomes of WS fibroblasts. A suggested model for abnormal DNA replication is presented and discussed to explain the loss of DNA and the chromosome abnormalities in WS cells. The abnormal DNA-synthetic profiles so derived appeared to be normalized in SV40-transformed PSV811 (WS) cells as were in gamma ray-transformed wild-type WI38CT-1 cells.

Adolescent↗
PubMed1985

Molecular cloning and nucleotide sequence of the HU-1 gene of Escherichia coli.

The Escherichia coli HU-1 was cloned by use of mixed synthetic oligonucleotides (17-mer) predicted from a portion of its amino acid sequence. The amino acid sequence of the HU-1 protein deduced from the nucleotide sequence is in good agreement with the published sequence. The nucleotide sequence has a possible promoter and a typical ribosomal binding site upstream from the translational initiation codon (GUG) of the HU-1 gene.

Amino Acid Sequence↗
PubMed1985

Disorders of cobalamin metabolism.

Recent developments in our knowledge of the biochemistry and metabolism of cobalamin have given us some insight into clinical disorders. N2O, which easily induces cobalamin deficiency, both in vivo and in vitro, has greatly contributed to the investigation of the cobalamin deficient state, especially in relation to folate and amino acid metabolism. Demonstration of the cobalamin analog in human serum and a new enzyme which requires cobalamin as a coenzyme has led to recent increased interest in this field. The disorders of cobalamin metabolism will be summarized briefly as well as those areas currently of particular interest.

5-Methyltetrahydrofolate-Homocysteine S-Methyltran↗
PubMed1985

Effects of aspartame on diabetic rats and diabetic patients.

The effects of aspartame (L-aspartyl-L-phenylalanine methyl ester) on plasma glucose and insulin levels were investigated in diabetic rats and patients with non-insulin-dependent diabetes mellitus. The oral administration of 0.45 mg aspartame per 100g body weight, which is equivalent to 150 mg of glucose in sweetness, to streptozotocin-induced diabetic rats had no effect on the plasma glucose or insulin levels. Also, 225 mg oral aspartame loading, which is equivalent to 75 g of glucose in sweetness, to patients with non-insulin-dependent diabetes mellitus did not increase plasma glucose or insulin levels, although 75 g of oral glucose loading increased plasma glucose and insulin levels in diabetic patients as expected. Aspartame ingestion for three days at a dose of 24-48 mg per day and the intake of snacks flavored with 240 mg of aspartame also did not increase fasting plasma glucose levels. These results suggest that acute administration of aspartame has no influence on plasma glucose or insulin levels in diabetic rats and patients with non-insulin-dependent diabetes mellitus.

Adult↗