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Biomedical subjects

K Tamura

Publications and source records attributed to K Tamura.

At least 739 records · Page 41Linked to original sources
PubMed1994

[Surgical treatment of arteriovenous malformations in the brain stem].

The authors report the surgical removal of four arteriovenous malformations (AVM's) in the brain stem causing hemorrhage. These included two intra-axial and two extra-axial AVM's. Three of the four were situated at the pons, and the remaining one in the posterior medullary velum. Complete surgical removal was obtained in the two extra-axial cases and in one of the intra-axial cases. The patient in whom complete removal was not obtained received partial embolization therapy with the remaining feeder being coagulated surgically. No patient was made permanently worse after surgery. One patient, in a comatose state on admission, died, while the remaining three patients showed useful recovery. These data indicate that surgical therapy with or without endovascular surgery appears to be possible for some AVM's and can be performed at an acceptable risk.

Adult↗
PubMed1994

Clinical features of 25 patients with aplastic anemia.

We experienced 27 patients with aplastic anemia (AA) during the period of 1984 to 1988. Of these, clinical characteristics of 25 patients who were followed up until death or at least for 2 years were evaluated. In terms of the degree of the initial hematological impairment, the patients were separated into 3 groups: 9 (36%) in severe, 11 (44%) in moderate, and 5 (20%) in mild impairment. The survival rates in 24 months after diagnosis were 44% in severe, 64% in moderate, and 100% in mild, indicating close relation between the degree of the initial hematological impairment and survival rates. 9 patients in a severe group received blood transfusion, anabolic steroids and/or high-dose corticosteroids, but these treatments resulted in an unsatisfactory outcome. It is suggested that they need other therapeutic modalities, including bone marrow transplantation. When the initial hematological data were compared between a group of patients who were alive for more than two years and a group of patients who died within two years, the mean granulocyte counts and reticulocyte counts of these two groups showed significant differences. However, the mean platelet counts were not significantly different. This indicates that the initial granulocyte count and reticulocyte count are indicators of prognosis in AA, and that the initial platelet count does not influence the prognosis.

Adult↗
PubMed1994

[Early phase II study of KW-2307 in advanced or recurrent breast cancer. KW-2307 Cooperative Study Group (Breast Cancer Section].

A multi-institutional early phase II study of KW-2307 (vinorelbine), a new vinca alkaloid derivative, in advanced or recurrent breast cancer was conducted in 15 nationwide hospitals. KW-2307 was intravenously administered once weekly at doses of 15 to 25 mg/m2. Sixty-five among the enrolled 69 patients were eligible. Response rates were 11.8% (2/17) with 15 mg/m2, 28.0% (7/25) with 20 mg/m2 and 17.4% (4/23) with 25 mg/m2, and the overall response rate was 20.0%. Once-weekly intravenous administration of 20 mg/m2 was estimated to be the optimal dose of KW-2307 from the results. The major side effect was leucopenia, which was the dose-limiting factor in this study. Other subjective or objective side effects included anorexia, nausea-vomiting, phlebitis, fever, general fatigue and stomatitis, but none of them was serious.

Adult↗
PubMed1993

Proximal and core DNA elements are required for efficient angiotensinogen promoter activation during adipogenic differentiation.

Angiotensinogen is abundantly expressed in adipose tissue as well as in liver where it is mainly produced. To address the mechanism of this adipogenic expression, promoter regions of the mouse angiotensinogen gene are fused to the chloramphenicol acetyltransferase reporter gene and stably transfected into 3T3-L1 preadipocytes. Promoter activity correlates well with an increase of mRNA levels during adipogenic differentiation, thereby demonstrating that the induction is primarily due to transcriptional activation. Deletion analysis indicates that the proximal promoter region from -96 to +22 is able to mediate the chloramphenicol acetyltransferase induction and identifies two transcriptionally active regions: AGE1 (position -399 to -139) and AGE2 (position -96 to -52). Heterologous promoter assay reveals that AGE1 behaves with a constitutive enhancer-like property and that AGE2 functions as a differentiation-inducible activator. Gel shift experiments show that AGE2 specifically binds a novel factor (AGF2), which is induced upon differentiation. Furthermore, a constitutive factor (AGF3) binds to the core promoter region including the exon 1 (from -6 to +22, AGE3). Mutations within either AGE2 or AGE3 that disrupt nuclear factors binding in vitro dramatically reduced the chloramphenicol acetyltransferase activation in the native promoter context. These results suggest that both AGE2 and AGE3 are necessary for mediating efficient activation of the mouse angiotensinogen promoter during adipogenic differentiation.

3T3 Cells↗
PubMed1993

Recognition nucleotides of Escherichia coli tRNA(Leu) and its elements facilitating discrimination from tRNASer and tRNA(Tyr).

In order to study how Escherichia coli leucyl-tRNA synthetase recognizes tRNA(Leu) and discriminates it from the other two class II tRNAs, tRNA(Ser) and tRNA(Tyr), various mutations were introduced into class II tRNA transcripts. The discriminator base A73, but not the anticodon sequence, was found to serve as a critical recognition element of tRNA(Leu). A base substitution at the invariant nucleotide A14, but not at any of the other nucleotides characteristic of the E. coli tRNA(Leu) isoacceptors among the three class II tRNAs, caused significantly damaged aminoacylation with leucine. A two base-pair deletion in the long variable arm also resulted in no significant decrease of activity. Transplanting the three tertiary elements characteristic of E. coli tRNA(Leu) (i.e. the location of the G18G19 sequence in the D-loop, the A15 U48 base-pair and the stem pairing pattern of the long variable arm) besides the discriminator base change introduced the leucine charging activity in terms of Vmax/Km, up to 0.1 of that for the normal sequence of tRNA(Leu) into both tRNA(Ser) and tRNA(Tyr). These results indicate that A73 and A14 (or its vicinity) are involved in recognition by leucyl-tRNA synthetase, and that several tertiary elements play a significant role in the discrimination of tRNA(Leu) from the other two class II tRNAs.

Base Sequence↗
PubMed1993

Ciprofloxacin and loperamide in the treatment of bacillary dysentery.

OBJECTIVE: To compare the safety and efficacy of loperamide plus ciprofloxacin with those of ciprofloxacin alone in the treatment of bacillary dysentery. DESIGN: Double-blind, placebo-controlled, randomized clinical trial. SETTING: Hospital in Thailand. PARTICIPANTS: Eighty-eight adults with dysentery seeking medical care between November 1990 and February 1992. Patients who had received prior antibiotics or antimotility drugs were excluded. INTERVENTION: All 88 patients with dysentery were treated with ciprofloxacin, 500 mg twice daily for 3 days. Forty-two of these patients were randomly assigned to receive loperamide, a 4-mg initial dose followed by 2 mg after every loose stool (as many as eight caplets [16 mg] daily), and 46 were randomly assigned to receive placebo. MEASUREMENTS: Stools were collected daily until resolution of diarrhea and again after 10 days. The time to passage of the last unformed stool, number of unformed stools, and symptoms were recorded after treatment. RESULTS: Shigella or enteroinvasive Escherichia coli (53%), Vibrio parahaemolyticus (16%), and Salmonella (7%) were the most common bacterial enteric pathogens identified in 88 patients with dysentery. In patients infected with Shigella or enteroinvasive E. coli, the median duration of diarrhea was 19 hours (25th to 75th percentiles, 6 to 42 hours) for those receiving loperamide plus ciprofloxacin compared with 42 hours (21 to 46 hours) for those receiving ciprofloxacin alone (P = 0.028). The median number of diarrheal stools for those receiving ciprofloxacin and loperamide was 2.0 (1 to 5 stools) compared with 6.5 (2 to 9 stools) for those receiving ciprofloxacin alone (P = 0.016). None of the participants had a temperature greater than 38 degrees C after 24 hours of treatment. None of the patients was infected with the same bacterial enteric pathogen more than 1 day after receiving treatment. CONCLUSIONS: Loperamide decreases the number of unformed stools and shortens the duration of diarrhea in dysentery caused by Shigella in adults treated with ciprofloxacin.

Adult↗
PubMed1993

Activation of mouse renin promoter by cAMP and c-Jun in a kidney-derived cell line.

We demonstrated that the mouse renin promoter from -365 to +16 can mediate the activation by cAMP and c-Jun in a kidney-cell dominant manner. Deletion analysis indicated that the region from -75 to -48 was responsible for the activation by cAMP. Furthermore, the core promoter region from -47 to +16 was sufficient to confer c-Jun inducibility.

Animals↗
PubMed1993

Analysis of a nonpeptide antagonist for substance P on myenteric neurons of guinea-pig small intestine.

CP-96,345 [(2S,3S)-cis-2-(diphenylmethyl)-N-[(2-methoxyphenyl)-methyl]- 1-azabicyclo[2.2.2.]octan-3-amine], a novel nonpeptide antagonist of the substance P receptor, was evaluated for blocking action at substance P receptors on myenteric neurons of guinea-pig small intestine. Intracellular electrophysiological recording was used to determine actions of the drug on excitatory responses to substance P, on slow and fast excitatory postsynaptic potentials and action potential initiation and propagation in the neurons. CP-96,345 suppressed responses to substance P. It also suppressed spike initiation and propagation in the neuronal processes, as well as in the somal membranes. The effects of the drug on substance P responses could not be attributed to an action at substance P receptors. The mechanism of action appeared to be a nonselective local anesthetic effect on initiation and propagation of action potentials.

Action Potentials↗
PubMed1993

Simple, rapid, and accurate determination of deletion mutations by automated DNA sequencing of heteroduplex fragments of the adenomatous polyposis coli (APC) gene generated by PCR amplification.

Germline mutations in patients with familial adenomatous polyposis were analyzed by polymerase chain reaction (PCR) amplification of the adenomatous polyposis coli gene. PCR products from heterozygous patients for deletions of this gene formed four distinct bands on polyacrylamide gel electrophoresis. The four fragments were subsequently purified and both strands of each fragment were directly sequenced, using an automated DNA sequencer and the same primers as those for PCR amplification. It was found that the two slower migrating fragments were "bulge" heteroduplexes, while the other two were homoduplexes made up of two wild-type strands and two deletion-mutant strands, respectively. The sites of deletions in the adenomatous polyposis coli gene could be exactly determined in four of the five patients. In an attempt to identify deletion-carriers of familial adenomatous polyposis at the presymptomatic stage, a family study was also carried out, and two children were found to have the same mutations as those of their affected parents. The direct sequencing of heteroduplex fragments generated during PCR amplification is a potentially useful method for detecting mutations of not only the adenomatous polyposis coli gene but also many other genes of genetic diseases.

Adenomatous Polyposis Coli↗