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Biomedical subjects

T Miyoshi

Publications and source records attributed to T Miyoshi.

At least 91 records · Page 5Linked to original sources
PubMed1996

Transcriptional activation of RACTK1 K+ channel gene by apical alkalization in renal cortical collecting duct cells.

We have previously demonstrated that RACTK1 cDNA encodes a pH sensitive K+ channel expressed in the apical side of renal collecting tubule cells. To determine whether extracellular pH induces the RACTK1 gene expression in the renal cortical collecting duct (CCD) cells, we measured mRNA of the RACTK1 using cultured rabbit CCD cells. Alkalization of incubation medium activated the transcription of the RACKTK1 gene in a time- and dose-dependent manner after 1 h, and reached a maximal level after 12 h. To examine whether the stimulation of mRNA by alkalization of body fluid occurs also in vivo, mRNA levels were measured in mice loaded with acid or alkali. The RACTK1 mRNA was increased in association with the rise in urinary pH. To examine side face of the effect of pH on stimulation of mRNA, we observed the effect of pH in the apical or the basolateral side in the preparation where CCD cells were cultured on filter membrane supports. Alkalization of the apical side but not of the basolateral side, was shown to be a determinant in inducting the RACTK1 mRNA. These findings suggest that, in addition to rapid direct regulation of RACTK1 K+ channel conductance by intracellular pH, this channel is also regulated by the changes in luminal pH through synthesis of channel protein by transcriptional activation.

Animals↗
PubMed1996

Cyclosporine-related encephalopathy following allogeneic bone marrow transplantation.

A 46-year-old man with chronic myelogenous leukemia received allogeneic bone marrow transplantation (BMT) from a partially human leukocyte antigen (HLA)-mismatched sibling. Cyclosporine (CYA)-related encephalopathy developed on days 10 and 21 following BMT, and CYA-related thrombotic thrombocytopenic purpura (TTP) developed on day 45 following BMT. We measured serum concentrations of thrombomodulin (TM) as a marker of endothelial injury. The concentrations of TM were increased during the encephalopathy or TTP and decreased following recovery. Since CYA can cause endothelial injury, we suggest that CYA-induced endothelial injury is common to the pathogenesis of both the encephalopathy and the TTP. CYA therapy should be reinstituted with extreme caution in patients with a past history of CYA-related encephalopathy, since readministration of a low-dose CYA can evoke the immediate return of the encephalopathy.

Bone Marrow Transplantation↗
PubMed1996

Neuroprotective effect of 4'-(4-methylphenyl)-2,2':6',2-terpyridine trihydrochloride, a novel inducer of nerve growth factor.

We have identified 4'-(4-methylphenyl)-2,2':6',2-terpyridine: trihydrochloride (SS701), which belongs to a family of a small unique neuroprotective agents. SS701 accelerated the production of nerve growth factor (NGF) in cultured astroglial cells, dose- and time-dependently. In in vivo studies, SS701, when administered 30 min after induced cerebral ischemia, neuroprotective effects on delayed neuronal death in Mongolian gerbils were evident. The neuroprotective effects of SS701 against ischemia-induced delayed neuronal death are attributed to stimulation of the production of NGF.

2,2'-Dipyridyl↗
PubMed1996

Electrophysiological characterization of RACTK1 K+ channel in stable cell line.

RACTK1 is a pH-sensitive K+ channel cloned from rabbit renal collecting tubule cells. To characterize the function of this K+ channel in more detail, RACTK1 was transfected to an established cell line and the patch-clamp study was performed. cDNA of RACTK1 was inserted in the pMAM vector and transfected to Chinese hamster ovary cells. In one of 36 cell lines, the channel protein as expressed by the dexamethasone-induced mRNA and was detected by the specific antibody. The RACTK1 K+ channel with 80 pS was consistently observed. In inside-out patch, Ca2+ at concentrations higher than 500 nM activated the channel. Open probability was decreased by protein kinase A (from 45 to 4.2%, n+6) but not by protein kinase C. Whole cell currents of the transformed cells represented K+ conductance that was not blocked by an addition of charybdotoxin but by apamin. RACTK1 K+ channel has similar, though not identical, characteristics to the Ca2+ -activated K+ channel. RACTK1 might therefore encode a subunit of the intermediate conductance Ca2+ -activated K+ channel observed in the apical membrane of the rabbit renal collecting duct.

Alkaline Phosphatase↗
PubMed1996

Studies on fatigue of night duty workers at a newspaper office.

Fatigue of night duty workers in different divisions of a newspaper office was investigated by physiological methods such as the Blinker, Flicker and grip methods. The relationship between fatigue and hematological parameters such as hemoglobin (Hb), the hematocrit (Ht), serum-free amino acid levels, and indices of liver function such as the GOT and GPT levels were also examined. The composing and press room workers mainly complained of the subjective symptom of muscle fatigue, while workers in the photo-engraving and editorial departments mainly complained of mental fatigue. The overall rate of fatigue in the newspaper office was about 38.1%, but varied from one division to another, being especially high in the photo-engraving and editorial departments. The subjects with fatigue had low levels of serum GOT and GPT and high levels of serum-gluconeogenic amino acids, such as aspartic acid, glutamic acid, prolin, glycine, and alanine. These altered levels of serum-free amino acids and GOT and GPT seemed to be due to increased secretion of adrenal corticoid hormone caused by the stress of fatigue.

Adult↗
PubMed1996

Reassessment of second look operation for epithelial ovarian cancer.

We retrospectively reviewed 91 patients with epithelial ovarian cancer who underwent second-look operation (SLO). SLO identified a persistent tumor in 18 (19.8%) of 91 patients. Of these 18 patients, 13 (72.2%) showed disease progression after SLO. Patients with a positive SLO in which the identification of the persistent disease was only possible by washing cytological study showed better prognosis than patients with macroscopic lesions. Of the 73 patients with a negative SLO, 12 (16.4%) developed recurrence after cessation of treatment. These 12 patients were from stage 1c to 3 with Grade 2 and 3 tumors. The SLO findings were more sensitive than the serum tumor marker in identifying persistent disease. Also we reviewed 55 patients having no SLO. Among 57 cases in stage 1 and 2 with Grade 1 tumor, there were no cases of recurrence, regardless of whether they had SLO or not. Our results suggest that SLO findings correlate well with the patient's prognosis. SLO may not be needed for patients in stage 1 and 2 with Grade 1 tumor. Patients with advanced stage disease with Grade 2 and 3 tumors have high-risk for recurrence after negative SLO. While SLO is still of benefit in management of ovarian cancer, refinements are needed to determine its indication and scheduling.

Adult↗
PubMed1996

[Mononeuritis multiplex associated with measles virus infection].

We describe a 19-year-old patient who developed mononeuritis multiplex associated with measles virus infection. On April 30th, 1995, he suffered from fever and skin eruption, which disappeared ten days later. Thirteen days later, he noticed weakness of the fingers of both hands and forearms, and pain on both elbow joints. He was admitted to our hospital on June 12th, 1995. Neurologic examination revealed weakness and sensory disturbance, confined to the distal aspects of the right radial nerve and left median nerve. The electrodiagnostic findings confirmed those of axonal neuropathy in the right radial and left median nerves. Routine laboratory studies were normal. The cerebrospinal fluid test and EEG were normal. The IgG and IgM antibody titers against measles virus continued to be elevated in serum over four months after the onset, while they were not elevated in the cerebrospinal fluid. The corticosteroid therapy was mildly effective. Although the pathogenesis of this case is unclear, we speculate that the mononeuritis multiplex was caused by vasculitis related to the persistent measles virus infection in both elbow areas.

Adult↗
PubMed1996

Short-latency somatosensory evoked potentials in patients with cervical compressive lesions: morphological versus functional examination.

We studied short-latency somatosensory evoked potentials (SSEPs) elicited by upper limb stimulation in 40 patients with cervical compressive lesions. Of these, 17 underwent MRI examination and the remaining 23 had myelography for the assessment of structural changes. The latencies of N11 and N13 recorded from the neck and P14 derived from the scalp were used to calculate the interpeak latencies from the Erb's point potential. Abnormalities of N11 implied a nerve root lesion whereas those of N13 with normal N11 indicated cervical cord involvement. In patients with normal N11 and N13, prolongation of P14, originating from the medial lemniscus, indicated a compressive lesion located above the level of entry to the spinal cord of the nerve stimulated. When MRI showed abnormal signals in the spinal cord, N11 or N13 or both were generally affected. SSEPs also detected functional abnormalities in the absence of morphologic changes on MRI. These findings suggest that SSEP is a sensitive technique to use as a test of functional integrity of the spinal cord.

Adult↗
PubMed1995

Specific deficit of the ON response in visual transmission by targeted disruption of the mGluR6 gene.

Taking advantage of the restricted expression of metabotropic glutamate receptor subtype 6 (mGluR6) in retinal ON bipolar cells, we generated knockout mice lacking mGluR6 expression. The homozygous mutant mice showed a loss of ON responses but unchanged OFF responses to light. The mutant mice displayed no obvious changes in retinal cell organization nor in the projection of optic fibers to the brain. Furthermore, the mGluR6-deficient mice showed visual behavioral responses to light stimulation as examined by shuttle box avoidance behavior experiments using light exposure as a conditioned stimulus. The results demonstrate that mGluR6 is essential in synaptic transmission to the ON bipolar cell and that the OFF response provides an important means for transmitting visual information.

Animals↗
PubMed1994

[Tumor blood flow measured by dynamic CT].

A method of measuring tumor blood flow by dynamic CT (DCT) was devised, and the reliability of data obtained by the new method was investigated. The subjects were 16 patients with superficial tumors who underwent measurement of tumor blood flow by both the new DCT-based method and 15O gas positron emission tomography (PET). The results showed that tumor blood flow as measured by the new DCT-based method was about 1.2 times greater than that measured by PET, and both data yielded a straight line passing almost through the origin (proportional relationships); the correlation coefficient was 0.836. On the basis of these studies, it was concluded that the newly devised DCT-based method yields reliable data in the measurement of tumor blood flow.

Adult↗
PubMed1994

The survival of rat cerebral cortical neurons in the presence of trophic APP peptides.

One function of Alzheimer amyloid protein precursor (APP) is the regulation of growth and differentiation in several types of cells, including fibroblasts, PC12 cells, and neurons. This activity is represented by a small stretch of amino acids in the center of the molecule around RERMS. The APP 17-mer peptide containing the RERMS domain supported survival and neurite extension of rat cortical neurons in a dose-dependent and sequence-specific manner. The APP fragment synthesized in Escherichia coli supported the survival and neurite extension of rat cortical neurons, whereas the mutant APP fragment lacking the 30 amino acids around the RERMS domain had drastically reduced activity to support the survival and neurite extension. The current study established APP as a neuron survival factor and determined that the sequence around RERMS is important for this function.

Alzheimer Disease↗
PubMed1994

Evaluation of serum lactate dehydrogenase activity for estimation of energy expenditure in human subjects.

We investigated the relationship between serum lactate dehydrogenase (LDH) activity and energy expenditure in young adults, evaluating their serum LDH activities in order to develop an index of energy expenditure. The results obtained were as follows. (1) There were significant correlations between the serum LDH activity and energy expenditure/day, energy expenditure/body weight/day and daily activity index in men. (2) There were significant correlations between the serum LDH activity and energy expenditure/day and daily activity index in women. (3) A group of men who 'rarely' exercised had lower levels of serum LDH activity than those who exercised 'sometimes' or 'usually', but little difference was noted between similar groups of women.

Adult↗