Biomedical subjects

T Shimamoto

Publications and source records attributed to T Shimamoto.

At least 127 records · Page 7Linked to original sources

PubMed1994

Telomere shortening in leukemic cells is related to their genetic alterations but not replicative capability.

We compared telomere length in donor leukemic cells and corresponding established cell lines from three patients with chronic myeloid leukemia (CML) and three with acute lymphoblastic leukemia (ALL) to study the relation between the immortalization capacity of hematologic neoplasms and telomere length. Six of the seven established leukemia cell lines (four CML and two ALL) carried additional chromosome changes and had shorter telomere repeats than those of the donor patients' leukemic cells; the remaining ALL line showed no significant difference in telomere length between fresh leukemic cells and the corresponding cell line. Thus, most established leukemic cells lose effective telomerase activity during the process of establishment, and reduction in telomere length of established leukemic cells appeared to be associated with the presence of additional chromosome changes.

Blotting, Southern↗

PubMed1994

Clinical and biologic characteristics of CD7+ acute myeloid leukemia. Our experience and literature review.

Six patients with acute myeloid leukemia (AML) expressing CD7 antigen (CD7+ AML) were studied. They consisted of five patients with M1 and one with an M2 morphology. Two cases expressed other lymphoid-associated antigens, in addition to CD7. The complete remission rate was 50%. One patient had central nervous system recurrence. Cytogenetic analysis demonstrated normal karyotypes in all the cases. All but one had germline configurations of the T-cell receptor (TCR) genes and immunoglobulin heavy chain gene. However, all did not have detectable recombinase activating gene-1 activity by the RT-PCR technique. We performed colony formation assay in two patients, and no enhancement of colony formation by granulocyte colony-stimulating factor was noted. The results presented here, together with those reported previously, suggest that CD7+ AML may demonstrate lineage infidelity.

Adult↗

PubMed1994

Serum total cholesterol and mortality in a Japanese population.

Although the relation between serum total cholesterol and coronary heart disease is well established, the relation with mortality from non-coronary disease is controversial. Inverse relations of serum cholesterol with hemorrhagic stroke and cancer have stimulated the examination of cholesterol-non-coronary mortality associations. The population surveyed is 12,187 men and women aged 40-69 years living in Yao City, a suburb of Osaka, who undertook baseline examinations between 1975 and 1984 and had no history of stroke and coronary heart disease at baseline. The subjects were followed on average 8.9 years until the end of 1988 using systematic mortality surveillance. During the follow-up, there were 343 deaths, comprising 170 cancer deaths (International Classification of Death 9th edition: ICD-9, 140-239), 21 coronary heart disease deaths (ICD-9, 410-414), 67 other cardiovascular deaths (ICD-9, 390-458 excluding 410-414), and 85 non-cardiovascular, non-cancer deaths. There was a significant inverse association of serum cholesterol with total and cancer mortality for men, and no significant association for women. The cholesterol-disease association, although not significant, was positive for coronary heart disease and other cardiovascular disease deaths, and inverse for non-cardiovascular, non-cancer deaths in both sexes. The inverse association of serum cholesterol with total and cancer mortality for men remained significant after controlling for age, job classification, hypertension category, usual alcohol intake, cigarette smoking, and relative weight index.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1994

Properties of the Na+/H+ antiporter in Vibrio parahaemolyticus.

The properties of the Na+/H+ antiporter in Vibrio parahaemolyticus, a slightly halophilic bacterium, were investigated using everted membrane vesicles. It appears that at least two Na+/H+ antiporters are present, one that is pH-dependent and one that is pH-independent. These two antiporters appear to correspond to the NhaA and NhaB antiporters of Escherichia coli, respectively. It seems that amiloride strongly inhibits the pH-dependent antiporter. Na+ is the best substrate for both of the two V. parahaemolyticus antiporters. Li+ is a poorer substrate and K+ is not a substrate. No K+/H+ antiport activity was detected in membrane vesicles of this organism. The Na+(Li+)/H+ antiport activity greatly increased with an increase in pH of the assay medium. pH did not affect the Km value of the Na+/H+ antiport, but it did increase the Vmax.

Hydrogen-Ion Concentration↗

PubMed1994

Transcriptional attenuation and differential mRNA stability in the regulation of the Escherichia coli melibiose operon.

The organization of the melibiose operon of Escherichia coli is promoter-melA-melB. The amount of the product (alpha-galactosidase) of the first gene (melA) is much larger than that of the product (melibiose permease) of the second gene (melB). Using the chloramphenicol acetyltransferase gene (cat) as reporter, we found that there was an element between melA and melB, which reduced the expression of the downstream gene, melB. This region contained a boxA-like sequence, which is known as a binding site for an attenuation factor, NusA. Northern hybridization analysis revealed that the ratio of melA mRNA and melAB mRNA was comparable with the ratio of the melA and melB products. We also found that the melA mRNA was about 3-fold more stable than the melAB mRNA. Experimental results obtained with a nusAts mutant suggested that the NusA protein is involved in the reduced expression of the melB gene. We conclude that the production ratio of alpha-galactosidase and melibiose permease is regulated at two levels: 1) transcription and 2) mRNA stability.

Base Sequence↗

PubMed1994

The NhaB Na+/H+ antiporter is essential for intracellular pH regulation under alkaline conditions in Escherichia coli.

We isolated a mutant of Escherichia coli which was defective in an Na+/H+ antiporter and grew poorly under alkaline conditions [Ishikawa, T., Hama, H., Tsuda, T., and Tsuchiya, T. (1987) J. Biol. Chem. 262, 7443-7446]. Later, it was concluded that the defective Na+/H+ antiporter in the mutant was the NhaB system, and the nhaB gene was mapped to 25.6 min on the E. coli chromosome [Thelen, P., Tsuchiya, T., and Goldberg, E.B. (1991) J. Bacteriol. 173, 6553-6557]. We found that the NhaB-defective cells cannot grow in a high pH medium. Furthermore, intracellular pH in the mutant cells was almost the same as extracellular pH between 7.9 and 9.1, that is, intracellular pH was not regulated at this pH range. On the other hand, intracellular pH of the wild-type cells was maintained at about 7.6 when the extracellular pH was between 7.6 and 8.5. Thus, the NhaB Na+/H+ antiporter is essential for the regulation of intracellular pH under alkaline conditions in E. coli. Introduction of nhaA gene into the mutant cells increased Na+/H+ antiporter activity, but did not restore the defective growth and defective intracellular pH regulation under alkaline conditions.

Bacterial Proteins↗

PubMed1994

Properties and sequence of the NhaA Na+/H+ antiporter of Vibrio parahaemolyticus.

A gene encoding an Na+/H+ antiporter was cloned from chromosomal DNA of the slightly halophilic marine bacterium Vibrio parahaemolyticus. The host was an Escherichia coli mutant that lacked both of the two major Na+/H+ antiporters, NhaA and NhaB. Untransformed mutant cells were unable to grow in the presence of 0.6 M NaCl or 0.1 M LiCl, but Na+ and Li+ were non-toxic to cells transformed with a plasmid carrying the antiporter gene. Membrane vesicles prepared from the original E. coli mutant did not show any detectable Na+/H+ (and Li+/H+) antiport activity. However, we observed high Na+/H+ (and Li+/H+) antiport activity in membrane vesicles prepared from the transformed cells. The activity increased greatly when the pH of the assay medium was increased from 7.0 and 8.5. This property is very similar to that of the NhaA Na+/H+ antiporter of E. coli. Drastic decreases in Km values for Li+ and Na+ were observed with membrane vesicles prepared from the transformed cells compared with those observed with V. parahaemolyticus vesicles. The amino acid sequence deduced from the nucleotide sequence of the cloned gene showed high homology (59% identity and 87% similarity) with the NhaA Na+/H+ antiporter of E. coli. Thus, we conclude that the gene we cloned and sequenced is the nhaA of V. parahaemolyticus. We also found that several regions of the NhaA protein showed sequence similarity with transport proteins from some other organisms. Such regions seem to be important for Na+ recognition, transport or amiloride binding.

Amino Acid Sequence↗

PubMed1994

Characterization of the autophosphorylation of Era, an essential Escherichia coli GTPase.

Era is an essential protein in Escherichia coli which binds both GTP and GDP and has an intrinsic GTPase activity. Studies on the role of GTP/GDP binding and GTPase activity in an attempt to understand its function lead to the observation that Era is autophosphorylated. The autophosphorylation reaction is specific for GTP and cannot use ATP as a phosphoryl group donor. The reaction velocity is of first order with respect to protein concentration, suggesting an intramolecular mechanism. Autophosphorylation occurs at serine and threonine residues. The major phosphorylated tryptic peptide isolated after autophosphorylation has been identified as ISITSR, from residue 33 to 38. The peptide contains the site of phosphorylation and two potential sites for serine and threonine phosphorylation. Subsequently, both the threonine residue at position 36 and the serine residue at position 37 were altered to alanine. The double mutant Era, but not individual single mutants, was unable to functionally complement the growth of an E. coli strain which cannot produce wild-type Era protein at high temperature. This suggests that either threonine 36 or serine 37 has to exist for the function of Era in vivo. In vivo phosphorylation of Era was also examined by two-dimensional gel electrophoresis. Era has been previously assigned two distinct positions having two different X-Y co-ordinates: one of the spots (H032.0) was identified as phosphorylated Era, indicating that a substantial portion of Era in the cell is indeed phosphorylated. Therefore, Era autophosphorylation is likely to play an important physiological role in the cell.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗

PubMed1994

Left ventricular mass and subsequent blood pressure changes among middle-aged men in rural and urban Japanese populations.

BACKGROUND: It has been suggested that echocardiographically determined left ventricular mass (LVM) is useful in the prediction of hypertension. To examine the relation between LVM and subsequent blood pressure (BP) change, a 6- to 8-year follow-up was conducted in adult Japanese men. METHODS AND RESULTS: LVM was determined by M-mode echocardiography using the American Society of Echocardiography formula among 354 normotensive men aged 30 to 59 years from a rural community (n = 193) and from urban companies (n = 161) in Japan between 1979 and 1983. BP was remeasured 6 to 8 years after baseline in 148 rural men (77%) and 127 urban men (79%). For men whose BP was remeasured, the mean +/- SD LVM index (LVM/body surface area [g/m2]) at baseline was 117 +/- 22 in rural men and 99 +/- 15 in urban men (the difference, P < .001). For both populations, LVM index was positively associated with age and physical activity but not with body mass index. Associations of LVM index with usual alcohol intake and initial BPs were generally weak. According to linear regression analyses after controlling for these covariates at baseline, a 20-g/m2 greater LVM index at baseline was associated with a 5 mm Hg increase in systolic and a 4 mm Hg increase in diastolic BP during the subsequent 6 to 8 years for urban men. A 1-mm greater average ventricular wall thickness was associated with a similar BP increase. For rural men, positive associations of LVM index with BP increase existed but were weak. The weaker association between LVM index and BP increase in rural compared with urban men was probably the result of effects of higher physical activity, leading to a larger left ventricular internal dimension. The increase in systolic and diastolic BPs over the 6 to 8 years of observation was significantly related to baseline LVM index in rural and urban men with a smaller internal dimension (rural men, < or = 49 mm; urban men, < or = 47 mm) but not in those with larger dimensions. CONCLUSIONS: An increased LVM index predicts subsequent BP increase in middle-aged normotensive men in the presence of a normal or small internal dimension.

Adult↗

PubMed1994

Lithium toxicity and Na+(Li+)/H+ antiporter in Escherichia coli.

The lithium ion (Li+) shows toxicity against Escherichia coli cells when present in a high concentration in the environment. Since Li+ is extruded from cells via a Na+(Li+)/H+ antiporter, this antiporter must be involved in the detoxification of Li+. Two Na+(Li+)/H+ antiporters (NhaA system and NhaB system) are known to be present in E. coli. We investigated the properties of the antiporters and the participation of these systems in the detoxification of Li+ using mutants lacking one of the antiporters, or lacking both of them. Although the affinity for Li+ of the two systems was almost the same, the Vmax value for Li+ transport of the NhaA system was about 12 times larger than that of the NhaB system. Wild type cells were unable to grow in the presence of 0.7 M LiCl. Although a wild type cell and a mutant lacking the NhaB system grew in the presence of 0.6 M LiCl, a mutant lacking the NhaA system did not. This second mutant grew in the presence of 0.1 to 0.2 M LiCl. A mutant lacking both the NhaA and NhaB systems could not grow in the presence of 30 mM LiCl.

Escherichia coli↗

PubMed1994

EVI1 expression associated with a 3q26 anomaly in a leukemia cell line derived from the blast crisis of chronic myeloid leukemia.

Two leukemia cell lines, TS9;22 and YS9;22, were established from different individuals with Philadelphia chromosome (Ph)-positive chronic myeloid leukemia in blast crisis. The reverse transcript-polymerase chain reaction (RT-PCR) technique revealed that both cell lines expressed GATA-1, GATA-2, and the stem cell leukemia (SCL) gene, consistent with a megakaryocyte lineage. Chromosome analysis revealed that TS9;22 cells show the Ph translocation without abnormality of chromosome 3. In contrast, YS9;22 cells show the Ph translocation and dic(3)(q26;p12). Northern analysis revealed that YS9;22 cells express the EVI1 (ecotropic virus integration-1) gene, possibly because of the chromosomal translocation in the 3q26 region; TS9;22 cells do not express EVI1. However, no rearrangements were detected over 600 kb upstream or over 900 kb downstream of EVI1 in the YS9;22 cell line, suggesting a different mechanism of EVI1 activation from that in leukemia cells with either a t(3;3)(q21;q26) or inv(3)(q21q26). These results indicate that EVI1 expression in YS9;22 cells is linked to the 3q26 abnormality and that EVI1 activation plays an oncogenic role in the blastic transformation of chronic myeloid leukemia.

Adult↗

PubMed1994

[A randomized controlled trail of intensive and usual community-based education for blood pressure control].

A 1.5 year community-based hypertension education program was conducted and evaluated for the feasibility and effectiveness as a program for primary prevention of cardiovascular disease. The subjects were determined to be hypertensive from cardiovascular examinations and composed of 104 untreated men and women aged 35-69 whose blood pressure levels were between 140 and 179 mmHg for systolic and/or between 90 and 109 mmHg for diastolic and who had no evidence of hypertensive end organ effects in the 1990 examination. They were randomly assigned to either an intensive education (IE) group (n = 53) or a usual education (UE) group (n = 51) and invited to education classes six months later. The IE consisted of four education classes in the first six months and another 4 classes in the next 12 months. For the UE, one class in the first 6 months and another class in the next 12 months were held. Health education was focused on reduction of sodium intake, a 30 minutes of walking, and if necessary, reduction of alcohol and sugar intake. Mean (SD) values of systolic blood pressure at the start of the education program were 144.8 (11.7) mmHg in IE and 144.5 (12.2) mmHg in UE. The respective diastolic means (SD) were 80.6 (7.8) mmHg and 80.3 (8.6) mmHg. The proportion of persons who started to receive antihypertensive medication was 8-9% in both groups at six months, and 13% in IE and 29% in UE at 1.5 years. IE showed a 6 mmHg greater reduction in mean systolic blood pressure than UE at both six months and 1.5 years. No significant difference was found in diastolic blood pressure levels over time between the two groups. Dietary improvements related to reduction of salt intake were more evident in IE than in UE. There was no significant changes in means and distributions of relative weight index and alcohol intake in either group. Subgroup analysis according to antihypertensive medication use indicated that reduction of systolic blood pressure levels was significantly larger in IE than in UE for both no medication and medication subgroups at 6 months and 1.5 years. While it was difficult to evaluate an effect of the program at 1.5 years because of the difference in the proportion of medication use between IE and UE, the results at 6 months suggest that this community-based program was effective in reducing systolic blood pressure levels.

Adult↗

PubMed1994

[Family make-up is associated with the admission rate of stroke patients--difference between Kochi and Shimane Prefectures and in a rural community].

Kochi Prefecture had a higher admission rate for patients with cardiovascular disease, particularly for stroke, than Shimane Prefecture which has a similar socio-economic level. Kochi Prefecture had a smaller average number of persons in a household, a lower proportion of three generation households, and a lower proportion of households with six persons or more than Shimane Prefecture. The decline in number of persons in a household was greater in Kochi Prefecture than in Shimane Prefecture from 1960 to 1985, especially between 1970 and 1975. The association between family make-up and hospital discharge one year after stroke was examined in a rural community in Kochi Prefecture. Two hundred forty nine patients aged 40 years and older who were admitted immediately after stroke events were registered between 1969 and 1988, and they were followed for one year. According to family make-up, the subjects were divided into four groups: 1) persons who lived with spouse and daughter-in-law, 2) persons who lived with spouse, 3) persons who lived with daughter-in-law, 4) persons who lived without spouse and daughter-in-law. Although mean age and the proportion of serious cases were not different between group 1 and group 4, the proportion of admitted patients of group 1 was significantly lower than that of group 4. About 60% of group 1 had households with six persons or more. Group 2 had the lowest proportion of admitted patients, but this group was significantly younger than other groups. Within group 3, the proportion of admitted patients was higher in households in which the daughter-in-law had a job than in households in which she did not. These results suggest that the high admission rate in Kochi Prefecture is attributable to households which are short of personnel for home care.

Adult↗

PubMed1994

GATA-1, GATA-2, and stem cell leukemia gene expression in acute myeloid leukemia.

Transcription factors play an important role in the normal developmental process of hematopoietic cells. However, expression of transcription factors and its implication in various human leukemias is not well understood. We have studied GATA-1, GATA-2, and stem cell leukemia (SCL) gene expression in 30 patients with acute myeloid leukemia (AML) by the reverse transcription-polymerase chain reaction assay. In AML both GATA-1 and SCL genes were commonly expressed in M6 and M7 leukemias, and also in leukemias bearing the platelet-associated antigen. We found some AML patients with GATA-1, but not SCL expression. Most CD7+ AML and t(8;21)(q22;q22)-AML were included in this group, which often demonstrated immunoglobulin heavy chain and/or T-cell receptor gene rearrangements. Consequently, GATA-1+ SCL- AML may originate from early myeloid progenitors. Moreover, most AML patients of the M3, M4, or M5 groups were GATA-1- SCL-. Our data suggest that the expression pattern of transcription factors may help to define distinct phenotypes of AML cells.

Acute Disease↗

PubMed1993

Antigens of tissue plasminogen activator and plasminogen activator inhibitor 1: correlates in nonsmoking Japanese and Caucasian men and women.

We reported in a 1987 preliminary study that tissue plasminogen activator antigen was significantly higher in American Caucasian men than in Japanese men. To further examine possible differences in fibrinolytic activity between the two races, an expanded study was conducted in a total of 300 nonsmoking men and women aged 47-69 years in two population-based samples: rural Japanese living in Akita and Caucasians living in Minneapolis-St. Paul, MN. Antigens of tissue plasminogen activator (t-PA) and plasminogen activator inhibitor 1 (PAI-1) were measured. Mean t-PA antigen was 2.3 ng/ml higher in Caucasian men than in Japanese men (P < 0.001), but no race difference was seen for women (P = 0.59). Mean PAI-1 was higher in Caucasians than in Japanese for both sexes, and the race difference in mean was 1.8 ng/ml for men (P = 0.07) and 4.4 ng/ml for women (P < 0.001). Both t-PA and PAI-1 were associated positively with body mass index and blood triglycerides for all sex-race groups, and positively with alcohol intake for Japanese and Caucasian men. Compared to Japanese, Caucasians of both sexes had higher levels of body mass index and blood triglycerides, and lower average intake of alcohol among men. Even when adjusted for body mass index, triglycerides, alcohol and other cardiovascular risk factors, the race difference in mean t-PA antigen persisted for men (P < 0.001), as did the difference in mean PAI-1 for men (P = 0.03) and women (P = 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1993

A receptor mediated delivery of an HIV-1 derived peptide vaccine.

One way of obtaining an enhanced production of specific antibodies against given antigens is to maximize the level of antigen presentation through artificially augmented antigen uptake by antigen presenting cells (APCs). In this respect, it has been shown that the receptor mediated endocytosis of antigens can be a very effective way to achieve this purpose. Such a process should also enhance the weak immunogenicity of synthetic peptides produced as artificial vaccines with amino acid sequences resembling those of epitopic sites of pathogens. In this report we used alpha 2-macroglobulin (a2M) which has specific receptors on macrophages (MFs) as a delivery protein and were able to induce high concentrations of antibodies against an HIV-1 derived synthetic peptide in mice. a2M enhanced immunogenicity of the peptide better than Freund's adjuvant did. We should be able to develop effective peptide vaccines by further improving this system.

Animals↗

PubMed1993

Reverse transcriptases from bacterial retrons require specific secondary structures at the 5'-end of the template for the cDNA priming reaction.

Multicopy single-stranded DNA (msDNA) is a peculiar molecule consisting of a single-stranded DNA that is branched out from an internal G residue of an RNA molecule (msdRNA) via a 2',5'-phosphodiester linkage. The genetic unit required for msDNA synthesis is designated "retron" and consists of msr (a gene for msdRNA), msd (a gene for msDNA), and a gene for reverse transcriptase (RT) in a single operon. To date, four different msDNAs have been isolated from Escherichia coli. They do not share any primary sequences in either RNA or DNA. To elucidate the specificity of bacterial RT for msDNA synthesis, the msr-msd region from retron-Ec67 was introduced into E. coli cells producing RT-Ec73, or the msr-msd region from retron-Ec73 into E. coli cells producing RT-Ec67. In both cases, msDNA was not synthesized. However, when the msdRNA coding regions (msr) for retron-Ec67 and -Ec73 were mutually exchanged and the chimeric genes were introduced into E. coli cells producing either RT-Ec67 or RT-Ec73, it was thus found that msDNA was produced only when msr and RT were from the same retron. Requirement of the msr region for msDNA synthesis by RT was further investigated by mutations in the msr region for retron-Ec67. These analyses revealed that there is a strict requirement for specific primary sequences as well as the secondary structure in msdRNA. This finding is discussed in relationship to the mechanism of the priming reaction of cDNA synthesis by eukaryotic retroviral RTs using tRNAs.

Bacterial Proteins↗

PubMed1993

Gastric emptying and bezoars in Japanese. Report of five cases.

Bezoars are conglomerates of undigested material in the stomach. Previous reports have shown that a decrease in secretion of pepsin and gastric acid and a delay in gastric emptying might contribute to their formation. To clarify the pathogenesis of the formation of gastric bezoars, we studied gastric emptying in five patients who presented with a bezoar. In addition, gastric acid secretion was studied in three of the cases. Gastric emptying was not delayed in any case, and there was no trend toward a decrease in gastric acid secretion. The five patients were successfully treated by the endoscopic fragmentation and enzymatic dissolution of the bezoars. We conclude that, in Japanese, factors other than a delay in gastric emptying are the main contributors to bezoar formation.

Aged↗