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Biomedical subjects

K Segawa

Publications and source records attributed to K Segawa.

At least 145 records · Page 8Linked to original sources
PubMed1986

Characterization of the chimeric SV40 large T antigen which has a membrane attachment sequence of polyoma virus middle T antigen.

A chimeric SV40 mutant, pMTPY, was constructed which codes for a large T antigen having the putative membrane attachment sites of polyoma virus middle T antigen at the carboxy-terminal portion. The mutant T antigen was detected exclusively in the cytoplasm of CV-1 cells transfected with pMTPY by a fluorescent antibody test. This mutant could not support viral DNA replication, but could immortalize secondary cultured rat brain (RB) cells. Immortalized RB cells produced nonkaryophilic large T antigen and also small T antigen. The amount of p53 expressed in those cells was larger than that in control RB cells. In addition, this mutant had the ability to transform NIH3T3 cells. The mutant nonkaryophilic large T antigen in NIH3T3 transformant was localized in cytoplasmic membrane fractions.

Animals↗
PubMed1986

Neoplastic transformation of rat 3Y1 cells by a transcriptionally activated human c-myc gene and stabilization of p53 cellular tumor antigen in the transformed cells.

Transformed foci were obtained in rat 3Y1 fibroblasts cotransfected with pRmyc 27 (transcriptionally activated c-myc) and pSV2neo DNA. RmycY cell lines (1 to 7) were established from these foci. RmycY cells were small and round and contained enlarged nucleoli in the nucleus. The myc gene was expressed in these cell lines at a much higher level than in 3Y1 cells and at a level similar to that in HL-60 cells. These cell lines formed colonies in soft-agar culture and tumors in syngeneic rats transplanted with RmycY cells. Expression of the gene and colony formation in soft-agar culture were analyzed in subclones from RmycY cell line 1. A correlation between myc gene expression and the ability to form colonies in soft-agar culture was observed in these cells. Antibody against p53 cellular tumor antigen was detected in some sera from tumor-bearing rats. p53 cellular tumor antigen stabilized and accumulated in RmycY cells to the same extent as in simian virus 40-transformed cells. The results suggest that elevated c-myc expression and an increased amount of p53 cause 3Y1 cells to become a more tumorigenic cell line.

Animals↗
PubMed1986

Determination of plasma retinol by high performance liquid chromatography, and its significance in digestive diseases.

Plasma retinol was determined by reverse-phase high-performance liquid chromatography in healthy subjects and patients with digestive diseases. The plasma retinol in the healthy control was independent of age (80.5 +/- 17.16 micrograms/dl). On the other hand, the amount of retinol in patient groups was lower than in the healthy control group. It was 30.96 +/- 7.16 micrograms/dl in patients with liver cancer, 38.02 +/- 11.63 micrograms/dl in those with chronic pancreatitis and pancreatic cancer, 45.36 +/- 12.63 micrograms/dl in a patient group with inflammatory bowel disease, 66.25 +/- 7.27 micrograms/dl in the patients of early gastric cancer, and 66.44 +/- 10.10 micrograms/dl in the group with biliary stone. These results and many biological aspects of retinol in human made it clear that, the special attention should be paid to the fluctuation of plasma retinol amount. This was considered to play an important role in causing complications associated with digestive diseases.

Adult↗
PubMed1986

Distribution of epithelial dysplasia in the cancerous esophagus.

A total of 114 cases, consisting of 20 non-cancerous esophagi, 48 non-irradiated cancerous esophagi, and 46 irradiated cancerous esophagi, were investigated with semiserial sections to evaluate the role of epithelial dysplasia as a precursor of esophageal cancer. The incidence of dysplasia was higher in cancerous esophagi than in non-cancerous esophagi and in non-irradiated cancerous esophagi than in irradiated cancerous esophagi. The difference in distribution pattern of dysplasia made it possible to classify the esophagi into three types: extensive, multifocal, and scanty. In the extensive type the main tumor tended to have an ill-defined margin and large diameter. In the multifocal type it tended to be superficial and small, and in the scanty type it usually had a well-defined margin. A possible relationship of epithelial dysplasia to the origin of esophageal cancer and its growth was shown by at least two thirds of the esophageal cancers.

Carcinoma, Squamous Cell↗
PubMed1986

Effects of three beta-blocker eye drops on the rabbit cornea: an electron microscope study.

The effects on corneal tissue of three marketed beta-blocker eye drops, carteolol 1% and 2%, befunolol 0.5% and 1%, and timolol 0.25% and 0.5%, were studied by instilling these drops into the eyes of rabbits twice daily for two consecutive months. The corneal sections were examined under a scanning electron microscope and a transmission electron microscope. Carteolol eye drops caused no pathological change in the corneal epithelium, whereas befunolol and timolol eye drops caused pronounced desquamation of the corneal epithelium and pronounced disappearance of microvilli. None of the three beta-blocker eye drops caused pathological changes in the parenchyma or endothelium of the cornea.

Adrenergic beta-Antagonists↗
PubMed1985

Formation of tight and gap junctions in the inner enamel epithelium and preameloblasts in human fetal tooth germs.

Human fetal primary tooth germs in the cap stage were fixed with a glutaraldehyde-formaldehyde mixture, and formative processes of tight and gap junctions of the inner enamel epithelium and preameloblasts were examined by means of freeze-fracture replication. Chains of small clusters of particles on the plasma membrane P-face of the inner enamel epithelium and preameloblasts were the initial sign of tight junction formation. After arranging themselves in discontinuous, linear arrays in association with preexisting or forming gap junctions, these particles later began revealing smooth, continuous tight junctional strands on the plasma membrane P-face and corresponding shallow grooves of a similar pattern on the E-face. Although they exhibited evident meshwork structures of various extents at both the proximal and distal ends of cell bodies, they formed no zonulae occludentes. Small assemblies of particles resembling gap junctions were noted at points of cross linkage of tight junctional strands; but large, mature gap junctions no longer continued into the tight junction meshwork structure. Gap junctions first appeared as very small particle clusters on the plasma membrane P-face of the inner enamel epithelium. Later two types of gap junctions were recognized: one consisted of quite densely aggregated particles with occasional particle-free areas, and the other consisted of relatively loosely aggregated particles with particle-free areas and aisles. Gap junction maturation seemed to consist in an increase of particle numbers. Fusion of gap junctions in the forming stage too was recognized. The results of this investigation suggest that, from an early stage in their development, human fetal ameloblasts possess highly differentiated cell-to-cell interrelations.

Ameloblasts↗
PubMed1985

Amino acid patterns in human gastric juice in health and gastric disease.

The amino acids in human gastric juice were measured in the hospital control (n = 9), gastric ulcer (n = 10), duodenal ulcer (n = 12), gastroduodenal ulcer (n = 9), and gastric cancer patients (n = 16) by high performance liquid chromatography, and the total of 15 kinds of amino acids was correlated with value determined by Ninhydrin method. The patients with gastric cancer had elevated levels of all amino acids, especially alanine, leucine, valine and threonine. In all but the gastric cancer disease groups, the aromatic amino acids, phenylalanine and tyrosine as well as leucine were at high levels in 15 amino acids. The different patterns of amino acids in these four groups tended to correlate with the variabilities of protein loss from the gastric wall.

Adolescent↗
PubMed1985

Amino acid in gastric juice of peptic ulcer patients.

To clarify the protein metabolism in peptic ulcer disease, the amino acid content was determined in gastric juice of gastric ulcer patients (n = 30), duodenal ulcer patients (n = 16), gastroduodenal ulcer patients (n = 8), and hospital controls (n = 8). The amino acid output in the gastric ulcer group was greater than that of the hospital control both in basal and maximal secretion. In the duodenal ulcer group of patients who were high secretors of gastric juice, the amino acid concentration was low, so the amino acid output was also lower than that of the hospital control group. Tetragastrin did not increase the amino acid output in the gastric juice. The amino acid amount may be decided also by the architecture of the gastric mucosa and not only by the ulcer lesion itself. The protein loss from gastric mucosa may well result in hypoproteinemia in peptic ulcer disease of the stomach.

Adult↗
PubMed1984

Intercellular junctions in the cells of the human enamel organ as revealed by freeze-fracture.

Examined by thin sections and freeze-fracture replication techniques, secretory ameloblasts possessed two sets of the junctional complexes at both proximal and distal ends of the cell bodies, which consisted of tight junctions and occasional gap junctions and desmosomes. The proximal tight junction was fascia occludens, whereas the distal tight junction was zonula occludens. Between adjacent ameloblasts, mature gap junctions were frequent. The stratum-intermedium cells were connected to each other and to the stellate-reticulum cells and ameloblasts by well-developed desmosomes, gap junctions and fascia or macula-type tight junctions. Stellate-reticulum cells were inter-connected by many extensive cytoplasmic processes, in which well-developed desmosomes, small gap junctions and occasional macula-type tight junctions appeared. Thus fascia or macula-type tight junctions as well as many desmosomes seem to serve in mechanical, cell-to-cell adhesion during tooth formation. Frequent and large gap junctions between adjacent stratum-intermedium cells and between the stratum intermedium and the base of the ameloblast suggest that, in relation to enamel formation, these two cell layers form a functional unit.

Ameloblasts↗
PubMed1984

The 1976-1977 rubella epidemic in Fukuoka city in southern Japan: epidemiology and incidences of complications among 80,000 persons who were school children at 28 primary schools and their family members.

From 1975 to 1977, a nationwide rubella epidemic occurred in Japan. This epidemic provided the last chance for the observation of natural rubella and its epidemiology without the influence of mass-vaccination for rubella and before changes in the epidemic pattern of rubella in the 1980's in Japan. Epidemiological and clinical data were obtained by questionnaires on school children in 28 selected primary schools and their family members (a total of 80,221 persons) in Fukuoka in southern Japan during the 1976-1977 rubella epidemic. At the end of 1975 the rubella epidemic was mainly in the western part of Fukuoka city and then it spread to the eastern part. After a break during the summer of 1976, the epidemic restarted in 1977 mainly in the eastern part with few cases in the western part. Rubella was identified clinically in 14,322 cases (18%) during the 1976 epidemic, the incidences in various age groups being as follows: children of below 6 years of age, 28%; primary school children, 37%; junior and senior high school students, 30%; adults of 18 to 30 years of age, 8%; adults of over 30 years of age, 1%. The incidence in primary school children in 1977 was 18%. Of the 14,322 cases of clinical rubella in 1976, 3 with encephalitis, 9 with purpura and 1,843 with joint complaints (pain and/or swelling of joints) were recorded. Rubella encephalitis was estimated to have occurred in 1 in 4,700 cases with clinical rubella, and purpura in 1 in 1,500 cases.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1983

Seroepidemiologic studies on rubella in Fukuoka in southern Japan during 1965-1981: rubella epidemic pattern, endemicity and immunity gap.

The epidemiology of rubella in most areas of Asia has not been defined. In Fukuoka city in southern Japan, rubella epidemics occurred in 1956-58, in 1966 and in 1976-77. During the first halves of the 1960s and 1970s, neither epidemic nor endemic clinical rubella occurred. Rubella mass vaccination for girls of 14 years of age started in 1978. Rubella seroepidemiologic studies were performed in 1965, 1974, 1978-79 and 1981 in Fukuoka city. Current studies indicated that children of 6-10 years of age during the epidemics of 1956-58, 1966 and 1976-77 were infected with rubella in 72%, 37% and 57% of cases, respectively. Just before the epidemics of 1966 and 1976-77 100% of the children under nine years of age had no antibodies to rubella indicating absence of recent outbreaks. Whereas 95% of the population (young women of 15-18 years of age in 1981) which participated in the rubella mass vaccination programme since 1978 have rubella Hl antibodies, 46% of the nonparticipating population (19-23 years of age in 1981) remains susceptible to rubella. These facts indicate that rubella epidemics occurred in 1956-58, 1966 and 1976-77, that the magnitude of each epidemic was different, and that there were intervals without endemicity in the inter-epidemic periods. However, after the nation wide rubella epidemic in 1975-77, endemic rubella continued, and rubella epidemics again occurred in 1980-82. The unique rubella epidemic pattern in Japan may be changing in the 1980s to that which existed in most areas of the world where rubella was endemic with periodic increased incidence of epidemicity.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗