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Biomedical subjects

K Tamura

Publications and source records attributed to K Tamura.

At least 811 records · Page 45Linked to original sources
PubMed1993

Cardiovascular properties of the new anti-ulcer drug 3-[[[2-(3,4-dimethoxyphenyl)ethyl]carbamoyl]methyl]-amino-N- methylbenzamide.

Cardiovascular activities of 3-[[[2-(3,4-dimethoxyphenyl)ethyl]carbamoyl]methyl]-amino-N- methylbenzamide (DQ-2511, CAS 104775-36-2), an anti-ulcer drug, were investigated in anesthetized dogs and conscious rats. In anesthetized and laparotomized dogs, DQ-2511 at intravenous doses of 5-50 mg/kg dose-relatedly induced an increase in celiac and mesenteric arterial blood flow, and a decrease in their resistance, whereas the drug had little or no effect on carotid and renal blood flow. DQ-2511 increased cardiac contractility in anesthetized dogs at an intravenous dose of 15 mg/kg. In addition to this effect, it produced an increase in respiratory rate, a decrease in blood pressure and a slight increase in heart rate after dosing at 50 mg/kg. The drug had little or no effect on femoral blood flow and produced no significant changes in the electrocardiogram. In conscious rats, blood flow in gastrointestinal organs was compared with flow in other organs using the microsphere method. Blood flow in the stomach, duodenum, ileum, pancreas, spleen, and kidney tended to decrease in the vehicle-treated control group. DQ-2511, at an oral dose of 100 mg/kg, significantly increased blood flow in the stomach, duodenum and spleen, and tended to increase flow in the pancreas, testis and fat in comparison with the vehicle-treated control group. Blood flow in the liver, heart and skeletal muscle tended to decrease, whereas the other regional blood flows did not differ from those in the control group. DQ-2511 at this oral dose had little or no effect on blood pressure, heart rate, cardiac output and total peripheral resistance in rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia↗
PubMed1993

[A case of external supravesical hernia].

The first report of external supravesical hernia was made by Astley Cooper in 1804, but it is so rare that we could not find any case reported in Japan. Here we report a case of external supravesical hernia in a male who had bladder cancer. This hernia was reported to be caused by fragility induced by operation or radiotherapy. It can be confused with inguinal direct hernia because it is not considered in the differential diagnosis. Findings such as a palpable hernia sack and the orifice can enable correct diagnosis. Surgical treatment is the only treatment of choice for this disorder.

Aged↗
PubMed1993

Cyclin G: a new mammalian cyclin with homology to fission yeast Cig1.

A new gene encoding a cyclin-like protein has been isolated from a rat fibroblast cDNA library by cross-hybridization with a mixture of c-src family proto-oncogene kinase domains as a probe. This putative cyclin, called cyclin G, contains a typical cyclin box at the N-terminus but no apparent 'destruction box' or 'PEST' sequence. Interestingly, in its C-terminus region, it has a sequence homologous with a tyrosine phosphorylation site of the epidermal growth factor receptor. Although this cyclin is phylogenetically related to HCS26 of Saccharomyces cerevisiae, it most resembles Cig1, a B-type cyclin, of Schizosaccharomyces pombe, which has been suggested to act at the G1/S phase of the cell cycle. Cyclin G mRNA is induced within 3 h after growth stimulation and remains elevated with no apparent cell cycle dependency, indicating its close association with growth stimuli but not with the cell cycle.

Amino Acid Sequence↗
PubMed1993

[Water-soluble eumelanin as a PCR-inhibitor and a simple method for its removal].

It has been confirmed that water-soluble eumelanins often extracted together with DNAs from natural black hairs act as an inhibitor of Taq DNA polymerase in the polymerase chain reaction (PCR). In the present investigation, an attempt to amplify the non-coding 333-bp region of mitochondrial DNA (mt333DNA) produced the following results: 1) Water-soluble preparations made from chemically synthesized melanin (Sigma products), as well as natural black eumelanins, inhibited the PCR amplification of mt333DNA at concentrations of more than 2 micrograms/ml. 2) Quantitative measurement of Taq DNA polymerase-catalyzed DNA synthesis in terms of the amount of [alpha-32P] dCMP incorporated into activated calf thymus DNA showed that both of the water-soluble melanins had the same inhibition activity as represented by the sigmoidal curve derived from a quadratic equation of melanin concentration. This observation suggested that Taq DNA polymerase combined with two molecules of melanin to form an inactivated complex. 3) Melanins did not appear to affect either the thermostability of Taq DNA polymerase at 94 degrees C, or the step of primer-annealing to template DNAs. On the other hand, we established a simple and useful method for removal of water-soluble eumelanins contaminating DNA preparations from hairs. The method was based on the adsorption of melanins to Bio-Gel. When a Bio-Gel P-60 minicolumn was equilibrated with 10 mM sodium acetate buffer, pH 4.2, water-soluble melanins were completely adsorpted to it whereas DNAs passed through, although the melanins showed incomplete adsorption to the gel when it was equilibrated with TE (10 mM Tris-HCl, pH 7.5, 0.1 mM EDTA).(ABSTRACT TRUNCATED AT 250 WORDS)

DNA, Mitochondrial↗
PubMed1993

[Molecular biology of alpha-adrenergic receptor and essential hypertension].

The primary physiological agents for adrenergic receptors are only two, epinephrine and norepinephrine, which have been used to differentiate alpha- and beta-adrenoceptors. The pharmacological properties can distinguish subtype alpha 1-, alpha 2-, beta 1- and beta 2-receptors. Recently additional subtypes have been characterized by radioligand binding techniques and molecular biological techniques. Molecular mechanisms of regulation as well as regulatory site of gene expression of alpha-adrenergic receptors has been extensively studied. In addition, the association analysis of alpha 2-adrenergic receptor gene RFLP in essential hypertension has been performed. Eventhough we could not find any association of an alpha 2 C10-Bsu36I RFLP with essential hypertension in Japan, the finding showed significant ethnic RFLP difference at the gene locus for alpha 2 C10. The association of alpha 2 adrenergic receptor RFLP with blood pressure has been also studied using F2 generations of SHR and WKY and Dahl salt sensitive rats and resistant rats. Further studies are now in progress to clarify the role of these alpha-adrenergic receptors in cardiovascular diseases.

Amino Acid Sequence↗
PubMed1993

Brequinar sodium inhibits interleukin-6-induced differentiation of a human B-cell line into IgM-secreting plasma cells.

Brequinar sodium (BQR) has been shown recently to be a potent immunosuppressive agent. This property has been attributed to the capacity of BQR to inhibit de novo pyrimidine nucleoside biosynthesis and consequently, to blockade the synthesis both of DNA and RNA. The influence of this new immunosuppressant on lymphocyte function has not been fully characterized. To determine the potential efficacy of BQR for the control of antibody-mediated graft rejection, which is of particular significance in the context of xenotransplantation, we have examined the influence of the drug on interleukin-6-dependent IgM production by the human B-cell line, SKW 6.4. At concentrations up to 10 micrograms/ml, BQR did not affect concanavalin A (Con A)-induced human peripheral blood lymphocyte proliferation or IL-6 production by blood mononuclear leucocytes. In contrast, the drug was very effective in inhibiting IL-6-stimulated IgM production by SKW 6.4 cells, with an optimal inhibitory concentration of 0.3 microgram/ml. As expected, addition of exogenous uridine (0.1 mM), the precursor of uridine triphosphate (UTP), reversed the inhibitory effect of BQR on antibody production, while cytidine (0.1 mM) potentiated the inhibitory activity of the drug. It was further demonstrated that the inhibition of IgM production was unrelated to DNA synthesis, indicating that BQR may affect IL-6 signal transduction and IgM production in SKW 6.4 cells independent of any effect on cell proliferation.

B-Lymphocytes↗
PubMed1993

[Neurological deterioration induced by giant intracranial aneurysms even though these aneurysms had not ruptured; mural hemorrhage and intraluminal thrombosis].

The authors report two cases of intracranial giant aneurysms inducing acute neurological deterioration even though rupture of the aneurysms had not occurred. Neurological aggravation was attributable to the acute swelling of the aneurysmal mass after intramural hemorrhage in one case, and the formation of rapid and massive intraluminal thrombosis in another case. MRI confirmed these mechanisms in both cases. MRI is very useful for demonstrating mural and intraluminal pathologies involving giant aneurysms.

Aneurysm, Ruptured↗
PubMed1993

[MR findings in traumatic cerebrospinal fluid leakage with special reference to indications of the need for dural repair].

Eleven cases of traumatic cerebrospinal fluid (CSF) leakage (8 cases of rhinorrhea and 3 cases of otorrhea) were reviewed to discuss magnetic resonance (MR) findings and surgical indications of the need for dural repair. Five patients had delayed onset of CSF rhinorrhea, 12 to 66 days (mean 28 days) after the trauma, and in the remaining 6 patients (3 rhinorrhea and 3 otorrhea) CSF leakage was noted on admission. MR study was carried out within 7 days after the onset of CSF leakage using a 0.5 tesla imager. In 7 cases of rhinorrhea, MR images demonstrated brain herniation into the ethmoid or frontal sinuses and the dural defects were repaired with the vascularized periosteum flap taken from the frontal bone or the fascia lata. In the operations, brain parenchyma was found to be plugged into the fracture line as MR images showed, and also to adhere to the margin of dural fistula. In the remaining 4 patients (without the MR findings of brain herniation into the paranasal sinuses) spontaneous cessation of CSF leakage occurred and their clinical course was good. Spontaneous cessation of CSF leakage in these cases may suggest the complete healing of the lacerated dura. However, in cases with the brain herniated into the paranasal sinuses CSF leakage may not be observed, and natural healing of the dural defect cannot be expected. Therefore, such brain herniation indicates the absolute need for dural repair even if CSF leakage is not observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Characterization of serum alpha 1-acid glycoprotein in fetal and newborn calves during development.

Serum alpha 1-acid glycoprotein (alpha 1-AG) in bovine fetuses and newborn calves was characterized. Serum alpha 1-AG concentration increased during fetal development and neonatal stages. Mean +/- SD serum alpha 1-AG concentration reached a peak of 1,368 +/- 207 micrograms/ml immediately after birth, but thereafter gradually decreased to 249 +/- 100 micrograms/ml, similar to the normal adult bovine range. By use of isoelectric focusing of thin-layer gels, we detected 7 microheterogeneity bands ranging from pI 3.2 to 3.8 in adult bovine serum. Twelve bands ranging from pI 2.6 to 3.8 were found in 9-month fetuses and in neonates. The 5 most-acidic bands, which are absent in adult serum, ranged between pI 2.6 and 3.1 and decreased with maturation as band patterns assumed adult characteristics. By crossed affinity electrophoresis, alpha 1-AG of adult bovine serum was separated into 4 peaks according to its differential affinity to concanavalin A (conA). Seventy-five percent of the alpha 1-AG concentration was represented by peak 3 (P-3) and peak 4 (P-4), which had moderate or strong binding to conA. In contrast, fetal sera contained only peak 1 (P-1), which did not have conA-binding affinity. In neonatal sera, 4 peaks were recognized, of which P-1 comprised 70% of the total alpha 1-AG. Thereafter, with aging, percentage of P-3 and P-4 increased as band composition approached the normally expected adult pattern.

Aging↗
PubMed1993

The influence of age and health status on the serum alpha 1-acid glycoprotein level of conventional and specific pathogen-free pigs.

Serum alpha-1-acid glycoprotein (alpha 1AG) was measured in 212 Landrace White pigs between birth and finishing age. The alpha 1AG level of healthy pigs five to ten months of age was 338 +/- 79 micrograms/mL, and the upper normal limit in mature swine has been established as 500 micrograms/mL. In both specific pathogen-free (SPF) and conventional pigs, the alpha 1AG level within one day of birth was 14,263 +/- 2,393 micrograms/mL, 40 times the normal adult value, but rapidly decreased to 699 +/- 186 micrograms/mL by four weeks of age. In conventional pigs, alpha 1AG began to increase after four weeks, averaged 1,428 micrograms/mL by eight weeks, but gradually decreased to adult levels by 20 weeks of age. In comparison, alpha 1AG of SPF pigs was only 800 micrograms/mL at eight weeks and decreased more rapidly to normal by 16 weeks of age. The conventional pigs had a high incidence of clinical pneumonia and specific antibodies to Actinobacillus pleuropneumoniae and Mycoplasma hyopneumoniae at the age of eight weeks. As the clinical pneumonia disappeared, serum alpha 1AG level also gradually declined. In contrast, SPF pigs had little clinical illness, low alpha 1AG, and little serological evidence of microbial infection. Conventional pigs with nonrespiratory infections, encephalitis, or with hernias had increased alpha 1AG. While the very high alpha 1AG level of the neonatal pig may be due to genetic influences, increases later in life are likely in response to stimuli from its external environment. Monitoring of serum alpha 1AG in several herds aided in the recognition of disease processes and may have potential use in swine herd health management.

Actinobacillus Infections↗
PubMed1992

Escherichia coli tRNA(Asp) recognition mechanism differing from that of the yeast system.

Various tRNA transcripts were constructed to study the identity elements of Escherichia coli tRNA(Asp). Base substitutions from G34 to U34 at the first position of the anticodon, and from U35 to A35 at the second, severely impaired the aspartate charging activity. The activity was also decreased, but in a more moderate fashion, by base changes at G2-C71, C36 and C38. Identity nucleotides of tRNA(Asp) are distributed in a different fashion between E. coli and yeast, which occur at the second base pair of the acceptor stem, G10-U25 base pair in the D-stem and 3' half of the anticodon loop.

Anticodon↗
PubMed1992

Effects of ethanol on the growth and elongation of Escherichia coli under high pressures up to 40 MPa.

The effects of ethanol on growth, viability and cell length were studied in Escherichia coli cultured under pressures up to 40 MPa (400 bar). A pressure of 10 MPa reversed the effect of ethanol in retarding cell growth. Cells cultured in the absence of ethanol became about seven times longer at 40 MPa than at atmospheric pressure, and some cells showed incomplete cell division. Ethanol also increased cell length but these effects were not seen at pressures of 20 MPa or more.

Escherichia coli↗
PubMed1992

High incidence of hepatocellular carcinomas induced by a choline deficient L-amino acid defined diet in rats.

The carcinogenicities of a choline deficient L-amino acid defined (CDAA) diet and a semipurified choline deficient diet were comparatively examined. A total of 60 male Fischer 344 rats, 6 weeks old, were divided into 5 experimental groups each consisting of 12 rats. Group 1 received the CDAA diet chronically to the end of the 52-week experiment while Group 2 was given the same diet for the first 24 weeks and then a basal diet for the following 28 weeks. Groups 3, 4, and 5 received a choline supplemented L-amino acid defined diet, the semipurified choline deficient diet, and a semipurified choline supplemented diet, respectively, throughout the experimental period. All surviving rats were subjected to complete macroscopic examination at Week 52. Histopathologically diagnosed hepatocellular carcinomas were induced in Group 1 at an incidence of 100%; multiple metastatic nodules were seen in the lungs of one of the animals. Hepatocellular carcinomas were also induced in Group 4 rats at a significantly lower incidence of 20%. No hepatocellular carcinomas were observed in rats in Groups 2, 3, and 4. The results indicate that the CDAA diet exerts more potent carcinogenicity for the livers of rats than does the semipurified choline deficient diet. However, limited exposure for 24 weeks may have not been sufficient for hepatocellular carcinoma induction by the CDAA diet at Week 52 although a high incidence of hyperplastic nodules and slight cirrhosis were evidence of persistent lesions.

Amino Acids↗
PubMed1992

Ammonia: a possible promotor in Helicobacter pylori-related gastric carcinogenesis.

Helicobacter pylori (HP) has been shown to possibly be a pathogen of gastric carcinoma. HP has urease activity and produces ammonia in the stomach. In this study, the role of ammonia on gastric carcinogenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) were investigated in rats. After 24 weeks pretreatment with MNNG (83 mg/l), 0.01% ammonia or tap water as a drinking water was administered for 24 weeks. The ammonia-treated rats showed a significantly higher incidence of gastric cancer (percent of animals with tumors and number of tumors per rat). Ammonia would thus appear to have an important role in HP-related human gastric carcinogenesis.

Adenocarcinoma↗
PubMed1992

A combination of upstream and proximal elements is required for efficient expression of the mouse renin promoter in cultured cells.

Renin, a key enzyme controlling blood pressure, is produced mainly in the kidney. To identify the transcriptional regulatory elements of the mouse Ren-1c gene, the promoter regions were fused to the CAT reporter gene and transfected into embryonic kidney-derived 293 cells and four extrarenal cell lines, HeLa, HepG2, HT1080 and NIH3T3 cells. Transient transfection assay showed that sequences from -365 to +16 of the renin gene could direct transcription of the CAT hybrid gene only in 293 cells. Deletion analysis identified two transcriptionally active regions; the renin upstream-promoter element (RU-1 element; position -224 to -138) and the renin proximal-promoter element (RP-2 element; position -75 to -47). Although the RU-1 element functioned as an activator, depending on its orientation, it failed to trans-activate the renin promoter when the RP-2 element was deleted. By contrast, the proximal element alone exhibited a weak trans-activator property. Gel shift assay identified RU-1 element-binding factors in both 293 and HeLa cells, whereas 293 cell-dominant factors were shown to bind only to RP-2 element. Therefore, both RU-1 and RP-2 elements were found to be necessary for efficient CAT expression from the renin promoter in 293 cells, suggesting that activation of the Ren-1c promoter requires combined action between cell type-dominant and ubiquitous nuclear factors.

Animals↗