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Biomedical subjects

T Tamaki

Publications and source records attributed to T Tamaki.

At least 19 recordsLinked to original sources
PubMed1995

Characterization of a GC-rich region containing Sp1 binding site(s) as a constitutive responsive element of the alpha 2(I) collagen gene in human fibroblasts.

To analyze regulatory elements in the human alpha 2(I) collagen gene (COL1A2) promoter, a series of deletion mutants from -323 to -186 base pairs was tested in transient transfection assays in human fibroblasts. A strong positive responsive element was mapped to a GC-rich region located between base pairs -303 and -271. This region contains three binding sites (GC-boxes) resembling recognition sites for the transcription factor Sp1. Substitution mutations in the GC-boxes abolished binding to the GC-rich region in gel shift analyses and resulted in 90% reduction of promoter activity in transient transfection assays. We demonstrated that transcription factor Sp1 is essential for binding based on the following observations. 1) Sp1 consensus binding site alone competes by binding to the GC-rich region in the DNase I protection assay; 2) both Sp1 consensus binding site and Sp1 antibodies prevent the formation of a DNA-protein complex in the mobility shift assay; 3) anti-Sp1 antibodies recognize a component of the complex competed for by Sp1 consensus binding site.

Base Sequence↗
PubMed1995

Effects of a synthetic rat adrenomedullin on regional hemodynamics in rats.

The effects of rat adrenomedullin, a novel vasorelaxant peptide, on systemic and regional hemodynamics were examined in conscious Sprague Dawley (SD) rats and spontaneously hypertensive rats (SHR). The intravenous infusion of adrenomedullin at rates of 1.67 and 5 micrograms/kg per min decreased the mean arterial pressure in a dose-dependent fashion in both types of rats. Adrenomedullin at a rate of 5 micrograms/kg per min increased the heart rate and cardiac output. As a result, the total peripheral resistance significantly decreased. With regards to the regional hemodynamics, adrenomedullin significantly increased the flow rates in the lungs, heart, spleen, kidneys, adrenal glands and small intestine of SHR. The flow rates in the brain and skin did not change and the flow rates in the skeletal muscle and testis were decreased. These regional hemodynamic changes were also observed in SD rats and there was no qualitative difference in the regional responses to adrenomedullin between SHR and SD rats. Thus, adrenomedullin predominantly increased the flow rates in organs in which adrenomedullin gene was highly expressed. It therefore seems that adrenomedullin may act as a local vasodilatory hormone rather than as a circulatory hormone.

Adrenomedullin↗
PubMed1995

Absolute and relative growth of rat skeletal muscle.

Change in body weight and lower hindlimb length as physical properties, muscle weight and length as whole-muscle properties, and fiber numbers, diameters, and numbers of proliferating cells as intramuscular properties, were measured in 2- to 60-week-old Wistar male rats. Results showed that the rapid increase in muscle weight (muscle mass) in the postnatal "growing phase" depended on the longitudinal and transverse growth. The increase in muscle length is due to longitudinal growth of muscle fiber, which may be derived from an increase in the number of sarcomeres. The increase in muscle girth depends on the increase of individual fiber diameter (muscle fiber hypertrophy) and fiber numbers (hyperplasia). The remaining increase in muscle mass in the "steady phase" (after the 10th week) is caused entirely by transverse growth, depending mainly on the muscle fiber hypertrophy (but may include increase of connective tissues). In conclusion, to study the effects of exercise and/or various overloads on muscle hypertrophy or hyperplasia, especially in the case of the plantaris muscle in Wistar rats, they should be 10-30 weeks old, and over 300 g in body weight, because in this period their characteristics remain most constant.

Animals↗
PubMed1995

Effect of transcranial magnetic stimulation on cerebral function in a monkey model.

The effect of transcranial magnetic stimulation on higher cerebral function was studied using 3 monkeys. They were trained in a delayed response task which required spatial short-term memory. The task was presented by a computer on a cathode-ray tube and results of the delayed response task, which consisted of the percentage of correct choices, reaction time and trial number, were analyzed. For stimulation, small and large round coils were used as well as a figure 8 configuration. Their maximal B-fields were 3.3 T, 1.9 T and 2.4 T, respectively. A total of more than 7000 stimuli were given to each monkey in various patterns. There was no deficit in the delayed response. Further complications such as epileptic seizures were not observed either. In conclusion, transcranial magnetic stimulation does not appear to have any effect on higher cerebral functions in monkeys.

Animals↗
PubMed1995

Degradation of humoral host defense by Candida albicans proteinase.

The effect of an extracellular proteinase from the pathogenic yeast Candida albicans on the bactericidal and opsonizing activities of human serum was studied. The ability of human polymorphonuclear leukocytes to kill Staphylococcus aureus was greatly reduced when the bacteria were opsonized with human serum treated with the proteinase. The reduction in the opsonizing activity of human serum was attributed to degradation of the Fc portion of immunoglobulin G by the action of C. albicans proteinase as determined by immunoprecipitation reaction. However, the Fab portion of immunoglobulin G was resistant to proteolysis by the proteinase. A clear reduction in the bactericidal activity of human serum against Escherichia coli was observed when the serum was treated with C. albicans proteinase. The reduction of serum bactericidal activity was attributed to the degradation of complement C3 by proteolysis by the proteinase as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, while C5 resisted the action of the proteinase. As determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the proteinase also degrades endogenous proteinase inhibitors, such as alpha 2 macroglobulin and alpha 1 proteinase inhibitor, which are involved in regulating inflammation. These results suggest that destruction of a host's defense-oriented or regulatory proteins facilitates debilitation of the infected host.

Aspartic Acid Endopeptidases↗
PubMed1995

Effect of moderately increased intrapelvic pressure on renal tissue pressure and vasopressin release in rabbits.

Electrical stimulation of afferent renal nerves and activation of intrarenal receptors increases plasma vasopressin concentration, but the role of afferent renal nerves in the control of vasopressin secretion is not clear. Recently, we reported that activation of renal mechanoreceptors stimulates the release of vasopressin. However, intrapelvic pressure was increased to 50 mmHg, and this increase is above the normal physiological range. Therefore, in the present study, we investigated the effect of moderately increased intrapelvic pressure on plasma vasopressin concentration in anesthetized rabbits. First, we measured renal tissue pressure while intrapelvic pressure was increased stepwise in 10-mmHg increments. Basal renal tissue pressure was 17 +/- 2 mmHg. Renal tissue pressure increased only when intrapelvic pressure was higher than the basal tissue pressure of each animal. Usually, increases in intrapelvic pressure less than 20 mmHg did not increase renal tissue pressure. This finding suggests that only increases in intrapelvic pressure more than 20 mmHg can activate renal mechanoreceptors. Based on this finding, the effects of moderate increases in intrapelvic pressure (15 and 30 mmHg) were studied. With a 15-mmHg increase in intrapelvic pressure, plasma vasopressin concentration did not change significantly. However, when intrapelvic pressure was increased to 30 mmHg, plasma vasopressin concentration increased from 5.6 +/- 1.4 to 9.5 +/- 2.8 pg/ml at 5 min (p < 0.05) and to 8.8 +/- 2.0 pg/ml at 10 min (p < 0.05). Plasma renin activity and mean arterial pressure also increased when intrapelvic pressure was increased to 30 mmHg. We conclude that moderate increases in intrapelvic pressure stimulate vasopressin secretion.(ABSTRACT TRUNCATED AT 250 WORDS)

Afferent Pathways↗
PubMed1995

Collagenous colitis.

Collagenous colitis is characterized clinically by chronic watery diarrhea and pathologically by colonic mucosal subepithelial collagen deposition. We report a 72-year-old woman who had collagenous colitis associated with chronic watery diarrhea. She received a non-steroidal anti-inflammatory agent (sulindac) because of rheumatoid arthritis. Histological examination of biopsy showed a thick subepithelial collagen layer with lymphocytes, plasma cells, and infiltration of a few eosinocytes in the lamina propria. These findings led to the diagnosis of collagenous colitis. After treatment with salazosulfapyridine, her bowel movement became normalized and mucosal subepithelial collagen deposition disappeared.

Aged↗
PubMed1995

Polymyositis associated with thymoma and the subsequent development of pure red cell aplasia.

A 53-year-old woman with polymyositis associated with thymoma subsequently developed pure red cell aplasia (PRCA). She was hospitalized because of fever and muscle weakness, and diagnosed as having polymyositis by muscle biopsy. Remarkable clinical improvement followed administration of prednisolone. Progressive anemia became evident, however, while prednisolone was being tapered. Erythroid aplasia and the presence of thymoma confirmed the diagnosis of PRCA. Further examinations revealed that cytotoxic T cells may play an important role in the pathogenesis of this case.

Cytotoxicity, Immunologic↗
PubMed1995

Gramicidin as a potential immunosuppressant for organ transplantation: suppression of human lymphocyte blastogenesis in vitro and prolongation of heart allograft survival in the rat.

Linear polypeptide antibiotic gramicidin is known to interact with the cell membrane and deregulate cation exchange. Because perturbation of cell membrane function may suppress the immune cell network, the authors investigated the effects of gramicidin on lymphocyte blastogenesis in vitro and allograft survival in vivo. Gramicidin blocked blastogenesis of human peripheral blood lymphocytes that responded to mitogens (IC50 = 0.2-10.1 ng/ml) or allogeneic lymphocytes (IC50 = 4.9 ng/ml). The extent of these suppressive effects was equal to or superior to that of cyclosporine or prednisolone. The antibiotic caused no apparent cytotoxicity at a dose of 10,000 ng/ml. The suppression of lymphocyte blastogenesis in vitro by cyclosporine or prednisolone was restored by addition of interleukin (IL)-1, IL-2, IL-4, IL-5 or IL-6. In contrast, none of these cytokines affected the suppressive activity of gramicidin on lymphocyte blastogenesis. The immunosuppressive efficacy of gramicidin was further examined in vivo in heterotopically heart-transplanted rats. A heart graft from (Lewis x BN) F1 donor was implanted in the neck of allogeneic Lewis rats. In this model, beating of the graft in control recipients (placebo group) stopped as a result of acute allograft rejection at 5.4 +/- 0.4 days after transplantation (n = 38), whereas beating of the graft in recipients that received 2.0 or 4.0 mg kg-1 day-1 of gramicidin i.p. for 6 days was significantly prolonged to 15.4 +/- 4.3 (n = 5) or 18.4 +/- 3.9 (n = 5) days after transplantation, respectively (P < .001).(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1995

General anesthetic effects on compound muscle action potentials elicited by single or dual spinal cord stimulation.

The aim of this study was to determine the optimal conditions, during general anesthesia, to obtain reproducible monitoring of compound muscle action potentials (CMAPs) as a means to evaluate motor tract integrity. The CMAPs were recorded in the soleus muscle of cats and were elicited by either single or double pulse stimulations (with various amplitudes and interpulse durations) of the spinal cord via an epidural electrode. The effects of various depths of general anesthesia with halothane, enflurane, isoflurane, or propofol on such recordings were also determined. For each agent, the CMAP amplitudes were significantly greater following double pulse stimulations (2-ms optimal interpulse duration) relative to single pulses. The CMAP amplitudes elicited by double pulse stimulations were the same at propofol concentrations of 50, 100, 150, and 200 micrograms/kg/min, whereas those for each volatile anesthetic, at all concentrations studied (0.5%, 1.0%, 1.5%, or 2.0%), were significantly lower. It was concluded that to obtain reliable CMAP amplitudes, general anesthesia with propofol should be employed and the potentials should be evoked by double pulse stimulations.

Action Potentials↗
PubMed1994

Nonrandom chromosomal rearrangements of 14q32.3 and 19p13.3 and preferential deletion of 1p in 21 patients with multiple myeloma and plasma cell leukemia.

Structural chromosomal abnormalities and their break-points were characterized in 17 patients with multiple myeloma (MM) and 4 with plasma cell leukemia by banding. Chromosome 14q32 translocations with a variety of partners were detected in 13 patients, and a variant translocation t(8;22)(q24.1;q11) was detected in 1. Three recurrent 14q32 translocations have been identified: t(6;14)(p21.1;q32.3) occurring in 3 cases, and t(11;14)(q13;q32.3) and t(14;18) (q32.3;q21.3) each occurring in 2 cases. Translocations t(1;14)(q21;q32.3), t(3;14)(p11;q32),t(7;14)(q11.2;q32.3), and t(11;14)(q23;q32.3) were found in each patient, whereas in the remaining 2 patients, partner chromosomes could not be determined. The band 19p13.3 was newly delineated as a recurrent breakpoint involved in translocations in MM. Chromosomes 1 and 6 were also commonly involved in structural abnormalities (14 and 10 patients, respectively), although no particular bands were noted. However, the short arm of chromosome 1 was preferentially involved in deletion, suggesting a certain antioncogene on 1p associated with the development of myeloma. In addition; fluorescence in situ hybridization was successfully applied to determine the nature of the structural abnormalities in a patient with t(8;22) translocation. The present findings suggest that there may be subsets of 14q32 translocations specific to MM.

Adult↗
PubMed1994

Activation of blood clotting factors by microbial proteinases.

There are very few reports on the involvement of bacterial proteinases on the blood clotting system using both human plasma and purified clotting factors. We studied whether microbial proteinases from the opportunistic pathogens Candida albicans, Pseudomonas aeruginosa and Serratia marcescens activate the blood clotting cascade by using normal human plasma, human plasmas deficient in clotting factor XII or X, and also by using purified clotting factors XII, X and prothrombin. All proteinases tested activated either clotting factor XII or prothrombin in vitro, thus resulting in generation of thrombin. Clotting factor X was converted to the active form (Xa) by both Candida and Pseudomonas proteinases, but not by Serratia proteinase. These results suggest that peripheral and systemic blood circulation may be impaired by activation of the blood clotting cascade by microbial infections, especially in septic patients, which would enhance disseminated intravascular coagulation and multi-organ failure.

Amino Acid Sequence↗
PubMed1994

The effects of volatile anesthetics on the relative amplitudes and latencies of spinal and muscle potentials evoked by transcranial magnetic stimulation.

STUDY DESIGN: The effects of halothane, enflurane, or isoflurane on motor-evoked potentials via transcranial magnetic stimulation were investigated in cats. Time and dose effects on muscle potentials and spinal potentials were determined by measuring relative changes in amplitudes and latencies. METHODS: In 16 cats, muscle potentials and spinal potentials were evoked transcranially using magnetic stimulation. Potentials were recorded every 2 minutes for 10 minutes at end-tidal anesthetic concentrations of 0.25%, 0.5%, 0.75%, or 1.0%, and for 10 minutes after agents were removed. RESULTS: These anesthetics significantly attenuated the amplitude, but not the latency of muscle potentials. Effects were reversible and time and dose dependent. In contrast, these agents had little or no effect on amplitudes or latencies of spinal potentials. CONCLUSIONS: Monitoring intraoperative changes in spinal potentials may provide useful information regarding motor pathway assessment, because anesthetics have minimal effects on spinal potentials, whereas this is not so for muscle potentials.

Anesthetics, Inhalation↗
PubMed1994

Appearance of complex branched fibers following repetitive muscle trauma in normal rat skeletal muscle.

BACKGROUND: To examine whether the complex branched fibers observed in mdx mutant mice were formed in normal skeletal muscles, long-term repetitive muscle trauma was applied to muscle of normal Wistar male rats. METHODS: Three kinds of artificial muscle trauma--crush injury, bupivacaine hydrochloride treatment, and forced stretching of contracting muscle (eccentric contraction)--were performed once a week for 10 weeks to achieve a state of repetitive degeneration and regeneration in the muscles. Two weeks after the final treatment, numerical, histochemical, and three-dimensional analyses by scanning electron microscopy were performed. RESULTS: Mean numbers of total branched fibers of the three groups were increased compared with normal control values, especially in the bupivacaine treatment group (three- to fivefold greater than in the other two groups). Aggregations of fibers of the same type which usually appear in mdx mice were observed in various parts of histological sections of the bupivacaine treatment group and only in a part of the crush injury group. No aggregations were observed in sections of the forced stretching group. In the three-dimensional analysis, complex branched fibers appearing as an "anastomosing syncytial reticulum" were observed only in the bupivacaine treatment group. CONCLUSIONS: These findings suggest that the formation of an anastomosing syncytial reticulum is one of the adaptation mechanisms of normal skeletal muscle rather than a specific event in mdx mutant mice, and long-term repeated trauma of the same fiber is necessary for this formation. Adaptive changes in the muscles with the three different types of muscle trauma are discussed.

Animals↗
PubMed1994

Ultrastructural changes in hepatocytes, sinusoidal endothelial cells and macrophages in hypothermic preservation of the rat liver with University of Wisconsin solution.

To identify subtle changes which might lead to liver failure after liver transplantation, rat livers stored at 4 degrees C in University of Wisconsin solution for 8, 16, 24, and 32 h were examined by transmission electron microscopy, scanning electron microscopy, cellular matrix maceration and freeze fracture for ultrastructural analysis. Endothelial cells exhibited aggregation of intramembrane particles (IMPs) at 8 h and produced tiny blebs accompanied by marked development of pits. As deterioration advanced, endothelial cells exposed the perisinusoidal faces of hepatocytes directly to the lumen with destruction of sieve plates. They then degraded with loss of IMPs. Macrophages followed a similar deterioration process to endothelial cells. Membranes of hepatocytes did not demonstrate aggregations of IMPs for 32 h. Rough endoplasmic reticulum (rER) lost ribosomes and smooth ER (sER) increased in amount and dilated in an irregular form. Autophagosomes appeared in the cytoplasm, engulfed cytoplasmic matrix containing intracellular organelles and became autophagic vacuoles. At 32 h bile canaliculi were filled with detached vesicles. This may be one of the causes of preservation related bile duct complications after liver transplantation.

Adenosine↗
PubMed1994

Changes in muscle oxygenation during weight-lifting exercise.

The quantitative analysis of haemoglobin oxygenation of contracting human muscle during weight-lifting exercise was studied noninvasively and directly using near-infrared spectroscopy. This method was developed as a three-wavelength method which confirmed the volume changes in oxygenated haemoglobin (oxy-Hb), deoxygenated haemoglobin (deoxy-Hb) and blood volume (total-Hb; Oxy-Hb+deoxy-Hb). Nine healthy adult men with various levels of training experience took part in the study. Ten repetition maximum (10 RM) one-arm curl exercise was performed by all the subjects. Results showed that at the beginning of the 10-RM exercise, rapid increases of deoxy-Hb and decreases of oxy-Hb were observed. In addition, total-Hb gradually increased during exercise. These results corresponded to the condition of arm blood flow experimentally restricted using a tourniquet in contact with the shoulder joint, and they showed the restriction of venous blood flow and an anoxic state occurring in the dynamically contracted muscle. In three sets of lifting exercise with short rest periods, these tendencies were accelerated in each set, while total-Hb volume did not return to the resting state after the third set for more than 90 s. These results would suggest that a training regimen emphasizing a moderately high load and a high number of repetitions, and a serial set with short rest periods such as usually performed by body builders, caused a relatively long-term anoxic state in the muscle.

Adult↗