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Biomedical subjects

Y Kitagawa

Publications and source records attributed to Y Kitagawa.

At least 253 records · Page 14Linked to original sources
PubMed1991

Phosphorylation of type II (beta) protein kinase C by casein kinase II.

Rat brain type II (beta) protein kinase C (PKC) was phosphorylated by rat lung casein kinase II (CK-II). Neither type I (gamma) nor type III (alpha) PKC was significantly phosphorylated by CK-II. CK-II incorporated 0.2-0.3 mol of phosphate into 1 mol of type II PKC. This phosphate was located at the single seryl residue (Ser-11) in the V1-variable region of the regulatory domain of the PKC molecule. A glutamic acid cluster was located at the carboxyl-terminal side of Ser-11, showing the consensus sequence for phosphorylation by CK-II. The velocity of this phosphorylation was enhanced by the addition of Ca2+, diolein, and phosphatidylserine, which are all required for the activation of PKC. Phosphorylation of casein or synthetic oligopeptides by CK-II was not affected by Ca2+, diolein, or phosphatidylserine. Available evidence suggests that CK-II phosphorylates preferentially the activated form of type II PKC. It remains unknown, however, whether this reaction has a physiological significance.

Amino Acid Sequence↗
PubMed1991

Induction of diabetes by PolyI:C and anti-RT6.1 antibody treatment in DR-BB rats.

To determine whether environmental factors could affect the incidence of diabetes in RT6.1+ lymphocytes-depleted diabetes resistant (DR) BB rats, we tested polyinosinic-polycytidylic acid (Poly I:C), as an immune activator, in conjunction with anti-RT6.1 antibody in DR-BB rats which were bred in a specific pathogen free (SPF) condition. Diabetes was induced by the combined administration of poly I:C and anti-RT6.1 antibody. The use of poly I:C or anti-RT6.1 antibody alone did not cause diabetes. These results suggest that RT6.1+ T lymphocytes regulate autoimmune diabetes and that non-specific immune activation caused by environmental factors plays a key role in inducing diabetes in DR-BB rats.

Animals↗
PubMed1991

[Inhibition by proton irradiation on the development of invasive bladder carcinomas induced by N-butyl-N-(4-hydroxybutyl) nitrosamine in mice].

Fifty-five female C3H/He mice were given 0.05% N-bytyl-N-(4-hydroxybutyl) nitrosamine in their drinking water for 18 weeks. In week 19, eleven mice (group 3) were sacrificed to confirm that they all had bladder carcinoma. The remaining mice were divided into two groups. Group 1 received 20 Gy of proton irradiation over the whole pelvis, while group 2 received no treatment as a control. After 3 weeks all the animals were sacrificed and their bladders were resected to weigh and to examine histologically. The average weight of the bladder, as an index of the tumor volume, was 67.7 mg in group 1, 120.6 mg in group 2 and 106.5 mg in group 3. There was a significant differences (p less than 0.05) between group 1 and group 2. The incidences of superficial (pT1) and deeply invasive (pT2-3) bladder carcinomas were [10/18 (56%) and 8/18 (39%)] in group 1, [3/17 (18%) and 14/17 (82%)] in group 2 and [2/11 (18%) and 9/11 (82%)] in group 3, respectively. These rates of incidence were significantly different (p less than 0.05) between group 1 and group 2. However, there was no significant difference (p = 0.068) between group 1 and group 3. These results indicate that proton irradiation is effective for treatment of invasive bladder carcinoma in mice.

Animals↗
PubMed1991

[Anticardiolipin antibody in cerebral infarction].

We investigated the anticardiolipin antibody (ACA) in a series of patients with cerebral infarction without systemic lupus erythematosus (SLA). Clinical and laboratory data were assessed from a series of 250 non-SLE patients with cerebral infarction who visited our clinic from 1988 to 1990. The concentration of anticardiolipin IgG antibody was measured by an enzyme-linked immunosorbent assay technique. An elevated ACA level was defined as one which was greater than 3 standard deviations above the mean level for normal controls. We examined the CT findings and risk factors for stroke such as hypertension, diabetes mellitus, hyperlipidemia and cardiac disease. Laboratory data such as the platelet count, the presence of lupus anticoagulant and a biologic false-positive test for syphilis were also investigated. Among the 250 patients with infarction, IgG ACA was detected in 22 (8.8%). There was no significant difference in incidence of ACA between the patients with cerebral thrombosis and those with cerebral embolism. On CT scan, multiple cerebral infarcts were noted in 18 of the 22 patients. As regards the location of the infarct, the cerebral cortex together with the basal ganglia was more common than isolated lesions of the cortex or basal ganglia. Concerning the risk factors for stroke, hypertension was noted in 12, diabetes mellitus in 2, hyperlipidemia in 2 and cardiac disease in 2. Lupus anticoagulant and thrombocytopenia were not detected in any of the cases. A biologic false-positive test for syphilis was observed in one case. Dementia was present in 12 of the 22 patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

[Cancer metastasis and recurrence from the standpoint of amplification and expression of oncogenes in human malignant tumors].

We investigated the amplification and expression of oncogenes in human malignant tumors. The survival rates of patients with c-erbB, c-erbB-2, and int-2 oncogene amplification/expression were significantly lower than those of the patients without gene amplification/expression. Many distant organ metastases were observed in esophageal cancer patients with int-2 amplification, in gastric cancer patients with c-erbB-2 over-expression, and in breast cancer patients with int-2 and c-erbB-2 amplification. These results suggest that the amplification/expression of these oncogenes may serve as good markers for determining the biological malignancy of cancers.

Gene Amplification↗
PubMed1990

Production of two variant laminin forms by endothelial cells and shift of their relative levels by angiostatic steroids.

Organization of endothelium as the lining of the cardiovascular system is supported by basement membrane. The important role of laminin and other basement membrane proteins is assumed in the angiogenesis. We show here that cultured endothelial cells produce two forms of laminin, and their relative levels are changed by antiangiogenic steroids. The synthesis of laminin subunits by endothelial cells isolated from bovine aorta and from bovine pulmonary artery was studied by metabolic labeling with [35S]methionine. Both endothelial cells produced a novel laminin-related polypeptide (A' subunit) in addition to the A, B1, and B2 subunits. Two-dimensional sodium dodecyl sulfate gel electrophoretic analysis showed that the B1B2 complex was first formed and the A subunit joined it to form the AB1B2 complex or the A' subunit joined it to form A'B1B2 complex. This mechanism implied that replacement of subunits in the complex by a corresponding variant produces variety in the structure and function of laminin. The A'B1B2 complex was the major product in endothelial cells under normal culture conditions. An angiostatic steroid, medroxyprogesterone, suppressed the A' synthesis and stimulated the A synthesis. Consequently, the major product of bovine aorta endothelial cells was converted to AB1B2. Two types of intracellular precursors were identified for each laminin-related polypeptide. Since the precursors in a given complex were synchronized with regard to maturation, the assembly of AB1B2 and A'B1B2 complexes was suggested to occur at an early step of intracellular processing.

Animals↗
PubMed1990

Complete and partial glycophospholipid anchors are found on a fusion protein consisting of luteinizing hormone beta subunit followed by a carboxyl-terminal domain of Thy-1.

The Thy-1 antigen is anchored to the cell surface by a carboxyl-terminal glycophospholipid moiety. To investigate the extent of anchor addition which occurs when such proteins cannot move efficiently to the cell surface, we have expressed a recombinant fusion protein composed of 107 amino-terminal amino acids of bovine luteinizing hormone beta subunit and 46 COOH-terminal amino acids of murine Thy-1 (Thy-1.2 allele). Although the limited amount of fusion protein transported to the cell surface is glycophospholipid-anchored, most of the protein accumulates in an intracellular, endoglycosidase H-sensitive form. The intracellular protein has an unusual structure that contains ethanolamine but does not bind detergent, suggesting either that anchor addition proceeds via a hydrophilic partial intermediate, or that anchor-degradative enzymes exist along the secretory path.

Animals↗
PubMed1990

Protein phosphatases possibly involved in rat spermatogenesis.

The expression of mRNAs for catalytic subunits of serine/threonine protein phosphatases 1 (PP-1) and 2A (PP-2A) in various rat tissues were examined. Four kinds of probes were used to detect mRNAs for two isotypes of PP-1 (dis2m1 and dis2m2), and two isotypes of PP-2A (PP-2A alpha and PP-2A beta). mRNAs for all of these four catalytic subunits were expressed in almost all tissues at substantial levels. They were expressed in two different sizes in most tissues. Remarkable evidence is that the smaller sized mRNAs of dis2m1 and PP-2A beta, 1.8 kb and 1.4 kb in length, respectively, were specifically highly expressed in testis. Both these smaller sized mRNAs began to be expressed at the age when meiosis started and were detected in testicular germ cells at the pachytene stage of meiotic prophase. Protein phosphatases which have peptides encoded by dis2m1 and PP-2A beta as catalytic subunits may play important roles in spermatogenesis.

Animals↗
PubMed1990

Production of shorter mRNA for protein phosphatase 2A beta by alternative poly(A) addition.

Two types of cDNA clones of protein phosphatase 2A beta, PP-2A beta L and PP-2A beta S, were isolated from a rat testis cDNA library. PP-2A beta L was 1.8 kb in length and corresponded to the 2.0 kb mRNA that is the major species expressed in somatic tissues. PP-2A beta S was 1.3 kb in length and corresponded to the 1.4 kb mRNA that is the major species expressed in germ cells of the testis. Nucleotide sequencing of these two clones revealed that their open reading frames were identical. The only difference between these two cDNAs was at the 3' non-coding region due to alternative poly(A) addition: the 1.8 kb cDNA had a consensus poly(A) addition signal, AATAAA, but the 1.3 kb cDNA had an unusual poly(A) addition signal, probably with the sequence AATATA. These data suggest that in germ cells there may be some mechanism that utilizes the specific poly(A) addition signal.

Animals↗
PubMed1990

Ascorbic acid phosphate stimulates type IV collagen synthesis and accelerates adipose conversion of 3T3-L1 cells.

We showed that the synthesis and secretion of type IV collagen, entactin, and laminin were enhanced when adipose conversion of 3T3-L1 cells at confluence was stimulated by hormones (Y. Aratani and Y. Kitagawa (1988) J. Biol. Chem. 263, 16163-16169). Ascorbic acid phosphate (Asc-P) stimulated the synthesis and secretion of type IV collagen and other collagens from both 3T3-L1 preadipocytes and adipocytes. The synthesis and secretion of laminin and entactin were not affected by Asc-P. The continuous addition of Asc-P stimulated cell growth and increased cell density at confluence 1.3-fold. Concomitantly, Asc-P remarkably accelerated the emergence of lipoprotein lipase, glycerophosphate dehydrogenase, and Oil Red O-stainable lipid droplets. These findings suggest an important role for type IV collagen in adipocyte differentiation.

Adipose Tissue↗
PubMed1990

Sequence analysis of rice dwarf phytoreovirus genome segments S4, S5, and S6: comparison with the equivalent wound tumor virus segments.

The complete nucleotide sequences of genome segments S4, S5, and S6 of rice dwarf phytoreovirus (RDV) were determined. S4 and S5 consist of 2468 and 2570 base pairs, respectively, S5 thus being larger in size than S4, contrary to the situation suggested by their relative migration in a polyacrylamide gel. S6 is 1699 nucleotides long. The individual segments have segment-specific inverted repeats adjacent to the conserved terminal sequences (5'GGUAAA---UGAU3' for S4, 5'GGCAAA---UGAU3' for S5 and S6). S4, S5, and S6 each have single long open reading frames encoding 727, 801, and 509 amino acids, respectively. A low level of amino acid sequence homology was observed between RDV S4 and wound tumor virus (WTV) S4 (22.4%), and between RDV S6 and WTV S6 (20.2%). On the other hand, RDV S5 and WTV S5 show 52.0% amino acid sequence similarity, indicating that S5 is much more conserved than any other segments of RDV and WTV reported so far. Further comparative analyses indicate that the RDV segment shows a greater frequency of usage of codons XYG and XYC, and much less frequent usage of codon XYA than the equivalent WTV segment, this codon preference bias being more conspicuous than expected from the base contents.

Amino Acid Sequence↗
PubMed1990

Sequence analysis of the rice dwarf phytoreovirus segment S3 transcript encoding for the major structural core protein of 114 kDa.

The primary structure of rice dwarf phytoreovirus (RDV) genome segment S3 was determined. RDV S3 consists of 3195 nucleotides. A 14-bp segment-specific inverted repeat is located immediately adjacent to the conserved terminal sequence (5'GGCAAA---UGAU3'). A single long open reading frame encoding for 1019 amino acids with an Mr of 114,289 is also identified. In order to investigate the localization of the predicted polypeptide, we determined the amino acid sequence of the 26-kDa peptide fragment obtained from the structural core protein digested by Staphylococcus aureus V8 protease. The sequence of the fragment was found in the translational product presumed from the nucleotide sequence of RDV S3, indicating that RDV S3 encodes the major structural core protein of 114 kDa.

Amino Acid Sequence↗
PubMed1990

Islet cell surface antibodies preferentially inhibit glucose-stimulated insulin release in vitro.

The effect of islet surface antibodies (ICSA) on in vitro insulin release was studied. Isolated rat islets were incubated in the presence of immunoglobulin preparations from patients with insulin-dependent and non-insulin-dependent diabetes mellitus (IDDM, NIDDM) and healthy subjects, and stimulated with D-glucose, L-arginine or tolbutamide. After incubation, the amount of insulin release from the rat islets was determined. The immunoglobulin preparations from 5 newly diagnosed IDDM patients who were positive for ICSA, and from 5 age-matched healthy subjects were examined. Even in the absence of complement or lymphocytes, immunoglobulin fractions positive for ICSA significantly inhibited low and high concentrations of glucose-stimulated insulin release compared with normal control (P less than 0.02), but had little influence on insulin release after stimulation with tolbutamide. Arginine-stimulated insulin release was almost the same in ICSA-positive immunoglobulin fractions and the control. Immunoglobulin fractions negative for ICSA either from four patients with recently diagnosed IDDM or from four newly diagnosed NIDDM patients had only negligible effect on insulin release after stimulation with glucose. These results suggest that ICSA in IDDM patients, even in the absence of complement or lymphocytes, may preferentially interfere with the mechanisms of glucose-stimulated insulin release in the pancreatic B cells.

Adolescent↗
PubMed1990

Dietary treatment ameliorates overt diabetes and decreased insulin secretion to glucose, induced by overeating in impaired glucose tolerant mice.

Overt diabetes (NIDDM) was induced by overeating in neonatally streptozocin (60 mg/kg.BW) treated impaired glucose tolerant mice. We imposed a food restriction and a high fiber diet to evaluate the effects of dietary treatment in this NIDDM model mouse. Furthermore, insulin secretion after the dietary treatment was studied using the perfused pancreas technique. One group of IGT mice (SZ) was maintained on ordinary mouse chow during 6 to 14 weeks of age. The others received a cookie and chocolate mashed diet (C.C. diet) to induce overt diabetes during 6 to 10 weeks of age. Thereafter, the mice with induced overt diabetes were divided according to their diet treatment. The C.C. diet was continued in one group (SZC) for 4 weeks, and the others were divided into a food restriction group (SZR: 4 g/mouse/day of ordinary mouse chow, for 4 weeks) and a high fiber diet group (SZF: 20% W/W of cellulose in ordinary mouse chow, for 8 weeks). The mean caloric intake/mouse/day in SZC, SZR and SZF were 140, 80 and 98% of that in SZ, respectively. Amelioration of hyperglycemia and impaired glucose tolerance was noted in SZR and SZF. A better glycemic control was obtained in SZF with keeping a normal growth rate. On the pancreas perfusion, the insulin secretion to 30 mM glucose was improved in SZR and SZF. Furthermore, the incremental first phase peak insulin release to 30 mM glucose in SZF was significantly greater than that in SZC (SZF, 10.5 +/- 1.0 vs. SZC, 4.5 +/- 1.9 microU/min).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Identification of members of the protein phosphatase 1 gene family in the rat and enhanced expression of protein phosphatase 1 alpha gene in rat hepatocellular carcinomas.

We isolated four kings of cDNA clones of isotypes of catalytic subunits of protein phosphatase 1 (PP-1) from rat liver and testis cDNA libraries. For the cloning, cDNA fragments of dis2ml and dis2m2, which encode mouse PP-1 catalytic subunit, were used as probes. Two of the four isotypes were thought to be derived from the same gene and produced by alternative splicing. Based on the comparative study of their nucleotide and deduced amino acid sequences with those reported, these cDNA clones were named rat PP-1 alpha, PP-1 gamma 1, PP-1 gamma 2 and PP-1 delta. The deduced amino acid sequences of these four cDNA clones showed about 90% identity. Their amino-terminal regions were highly conserved, and their differences were mainly in the carboxy-terminal regions. Furthermore, several amino acids located in the middle regions of the peptides were conserved in all the isotypes of the catalytic subunits of PP-1, PP-2A, PP-2B and PP-2C. These conserved regions are suggested to be the functional domains of the catalytic subunits of protein phosphatases. Rat hepatocellular carcinomas induced by a food mutagen, 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline showed increased expression of PP-1 alpha, but no increased expression of PP-1 gamma 1, PP-1 gamma 2 or PP-1 delta. Involvement of PP-1 alpha in hepatocarcinogenesis or in hepatic cell proliferation was suspected.

Amino Acid Sequence↗