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Biomedical subjects

T Shimizu

Publications and source records attributed to T Shimizu.

At least 217 records · Page 12Linked to original sources
PubMed2001

Single fiber EMG and repetitive nerve stimulation of the same extensor digitorum communis muscle in myasthenia gravis.

OBJECTIVE: To compare voluntary single fiber electromyography (v-SFEMG) and repetitive nerve stimulation (RNS) at the same extensor digitorum communis (EDC) muscle in myasthenia gravis (MG). METHODS: We examined v-SFEMG and RNS successively on the same day in the same EDC muscle. We studied 45 examinations of both v-SFEMG and RNS in 29 patients suffering from MG, together with examinations of RNS in 30 control subjects. RESULTS: Forty-one of 45 (91%) v-SFEMGs showed abnormal results, whereas only 18/45 (40%) RNSs showed an abnormal decrement. The percentage of decrement showed similar correlations with 3 v-SFEMG parameters: percentage of abnormal pairs, percentage of blocking pairs, and the mean MCD value. Examinations showing a significant decrement in RNS had at least 60%, and usually no less than 90%, abnormal pairs, and 10-80% blocking pairs. Some muscles without a decrement had up to 50% blocking pairs. CONCLUSIONS: These results suggest that the blocking phenomenon observed in v-SFEMG is not a direct counterpart of the decrement in RNS. This must be partly because fibers contributing to the decrement are continuously blocked during voluntary contraction, and partly, because smaller motor units explored by v-SFEMG are probably more abnormal in MG than larger motor units mainly contributing to a decrement. Both factors make v-SFEMG much more sensitive than RNS.

Adult↗
PubMed2001

Hypersomnia due to acute disseminated encephalomyelitis in a 5-year-old girl.

A 5-year-old girl suffering from hypersomnia due to acute disseminated encephalomyelitis (ADEM) is reported. Brain CT revealed a large low-density lesion involving the lentiform nucleus, posterior limb of the internal capsule, thalamus, posterior hypothalamus and midbrain in the left side. She was treated with intravenous dexamethazone. After the initial dose of dexamethazone, hypersomnia was dramatically and rapidly improved. A later brain CT study disclosed that the lesion in the brain disappeared. The brain lesion in this case involved the waking center in the brain, which was described by Von Economo. We concluded that hypersomnia in this case was due to ADEM involving the neural mechanism for maintaing wakefulness, probably in the thalamus and posterior hypothalamus. Repeat all night polysomnograpy in this case disclosed prolonged total sleep time and increased amount of stage 3-4 sleep in the hypersomniac state.

Journal Article↗
PubMed2001

Ets-1 is involved in transcriptional regulation of the chick inducible nitric oxide synthase gene in embryonic ventricular myocytes.

In order to elucidate roles of Ets family of transcription factors in transcriptional activation of inducible nitric oxide synthase (iNOS) genes, we analyzed the chick iNOS gene expression in cultured chick embryonic ventricular myocytes (CEVM). Deletional analysis and site-directed mutagenesis demonstrated that both the Ets/PEA3 site (-221 to -216 bp) and the kappaB site (-101 to -93 bp) of the 5'-flanking region of the chick iNOS gene were involved in the maximal activation of the lipopolysaccharide (LPS)-induced expression of the reporter (luciferase) gene, although the proximal kappaB site played the more essential role. Electrophoretic mobility shift assay revealed that LPS augmented the nuclear protein bindings to the Ets/PEA3 as well as kappaB motifs. Ets-1, one of the Ets proteins, was suggested to be bound to the Ets/PEA3 oligonucleotide. By Northern blot analysis, LPS was shown to induce iNOS mRNA in CEVM, along with a preceding increase in the levels of c-ets-1 mRNA. Ets-1 may be involved in the iNOS gene transcription in CEVM, presumably through interacting with the NF-kappaB.

Amino Acid Motifs↗
PubMed2001

Study of the factors influencing peak asymmetry on chromatography using a molecularly imprinted polymer prepared by the epitope approach.

Investigations of the effect of sample load on peak asymmetry during chromatography on molecularly imprinted polymer prepared by the epitope approach showed that the shape of the peaks for the template Tyr-Pro-Leu-Gly-NH2 and for acetyl-L-tyrosine ethyl ester changed considerably until a split was observed. In contrast, the asymmetry of the peaks corresponding to oxytocin, which possesses the same C-terminus tripeptide as the template and interacts with the imprinted polymer, remained essentially unaltered. The circular dichroism (CD) spectra of these peptides showed significant dependence on peptide concentration, and the dependence was nearly the same for all the tested peptides. The addition of acetic acid influenced the CD spectra of YPLG and oxytocin but had no influence on the spectrum of acetyl-L-tyrosine ethyl ester. The shape differences in the chromatographic peaks seem to be associated with a solvation mechanism rather than with solute-solute complexation in solution. However, the observed differences in peak asymmetry cannot be completely explained by the mechanisms that have been postulated previously. Our results suggest the formation of triple complexes between a solute molecule (or molecules), an already adsorbed solute molecule, and an adjacent region of the polymeric stationary phase. These triple complexes may influence the retention of analytes and contribute to peak asymmetry.

Chromatography, High Pressure Liquid↗
PubMed2001

A case of rapid progressive glomerulonephritis with IgA deposits after renal transplantation.

A 46-yr-old Japanese male who underwent a second cadaveric kidney transplantation on 31 October 1996 after suffering Type II diabetic mellitus for 25 yr was admitted to our institute on 23 January 1999, because of colicky abdominal pain and abdominal discomfort. Elevated levels of serum creatinine, severe proteinuria and microscopic haematuria were observed. The allograft biopsy specimen disclosed crescentic glomerulonephritis. Immunofluorescence showed granular deposits of mainly IgA and C3 along glomerular capillary walls and mesangial areas. Electron microscopy showed extensive subepithelial and mesangial electron dense deposits. Rapid and irreversible worsening of graft function led to resumption of haemodialysis on 31 May 1999. We speculated that this case was an atypical form of de novo Henoch-Schönlein purpura nephritis (HSPN) in transplanted kidney because of the histopathological findings of the allograft biopsy and clinical symptoms.

Cadaver↗
PubMed2001

Analysis of portal venous waveform after living-related liver transplantation with pulsed Doppler ultrasound.

We evaluate the portal venous waveform (PVW) with pulsed Doppler ultrasound (US) after living-related liver transplantation (LRLT) and correlate it with subsequent abnormalities. In the first 2 wk after LRLT, pulsed Doppler US demonstrated three types of PV waveform (PVW) in 33 recipients: non-phasic PVW in 19 patients, pulsatile in 10, and turbulent in 4. In the pulsatile PVW group, arterio-portal (A-P) shunt was confirmed in three grafts by either arteriograhy or computed tomography during hepatic arteriography. A severe stenosis in the grafted vein was confirmed in one case by both US and venography. The pulsatile PVW in the remaining six cases spontaneously disappeared and turned to the non-phasic PVW without treatment. The graft volume/liver standard volume (GV/SV) ratio was significantly smaller in the pulsatile PV waveform group than in the non-phasic PVW group (p<0.01). In the turbulent PVW group, aneurysmal-like dilatation of the portal vein at the umbilical portion was formed in 3 of the 4 patients. The pulsatile waveform in the PV is frequently observed with pulsed Doppler after LRLT, especially in patients that received small grafts. We should keep in mind that they often disappear without any treatment, although some examples of pulsatile waveforms represent vascular complications.

Adolescent↗
PubMed2001

Polymorphisms in the tumor necrosis factor (TNF) genes are associated with susceptibility to effects of ultraviolet-B radiation on induction of contact hypersensitivity.

We investigated the allelic distributions of single nucleotide polymorphisms (SNPs) of the TNFA, TNFB and IKBL genes, 3 microsatellites within the tumor necrosis factor (TNF) region of HLA locus, and the HLA phenotypes as well as the TLR4 gene in Chromosome 9 in 26 healthy Caucasian volunteers. These individuals were also assessed as ultraviolet B (UVB)-susceptible (S) or UVB-resistant (R). Our results identified 12 UVB-S and 14 UVB-R individuals. Attempts to correlate particular HLA-A, -B, -C, and -DR antigens with the UVB phenotypes failed. Similarly, attempts to correlate SNP at the NcoI-RFLP within intron 1 of the TNFB, IKBL and TLR4 gene with UVB phenotypes also failed. However, microsatellite analyses of TNFa, TNFc, and TNFd markers revealed a significant increase in the frequencies of TNFa2 in UVB-S individuals (P=0.00032) and of TNFd3 in UVB-R individuals (P=0.012). Moreover, DNA sequencing analyses of 5 SNPs of the TNFA promoter region revealed a significant increase in the frequency of the allele B of the TNFA gene (TNFApB) representing the nucleotide A at position -863 and C at position -1031 (P=0.015). Since it is known that TNFa2 and TNFApB is a high TNF-alpha responder, whereas TNFd3 is a TNF-alpha low responder, we propose that the TNF region of HLA contains polymorphic genes that confer susceptibility and resistance to the deleterious effects of UVB radiation on the induction of contact hypersensitivity. This proposal is consistent with previous reports that a unique microsatellite region of the Tnfa gene in mice contains alleles that dictate the UVB-dependent phenotypes in mice, and implicate TNF-alpha as the primary mediator of the immune-damaging effects of UVB radiation.

Adaptor Proteins, Signal Transducing↗
PubMed2001

Enhanced growth suppression in esophageal carcinoma cells using adenovirus-mediated fusion gene transfer (uracil phosphoribosyl transferase and herpes simplex virus thymidine kinase).

Advanced esophageal cancers are highly malignant and frequently resistant to 5-fluorouracil (5-FU). Escherichia coli uracil phosphoribosyltransferase (UP) is a pyrimidine salvage enzyme that alters 5-FU metabolism and sensitivity. A recombinant adenovirus encoding the UP gene (AxCA.UP) has been applied in gastric cancer gene therapy to sensitize cancer cells to lower concentrations of 5-FU. We have generated a recombinant adenovirus (AxCA.UT) encoding UP and herpes simplex virus thymidine kinase fusion protein (UT) to examine whether it would enhance the antitumor activity of AxCA.UP treatment. AxCA.UT treatment significantly enhanced the sensitivity of human esophageal cancer cells to and significantly enhanced the growth inhibition effects of UP gene therapy in vitro. Moreover, both 5-FU and ganciclovir showed bystander effects on growth inhibition. In an in vivo study, the therapeutic outcome of AxCA.UT treatment significantly enhanced the antitumor activity of AxCA.UP treatment. These observations suggest that AxCA.UT may be useful in esophageal cancer gene therapy.

Adenoviridae↗
PubMed2001

Control of electron transfer in neuronal NO synthase.

The nitric oxide synthases (NOSs) are dimeric flavocytochromes consisting of an oxygenase domain with cytochrome P450-like Cys-ligated haem, coupled to a diflavin reductase domain, which is related to cytochrome P450 reductase. The NOSs catalyse the sequential mono-oxygenation of arginine to N-hydroxyarginine and then to citrulline and NO. The constitutive NOS isoforms (cNOSs) are regulated by calmodulin (CaM), which binds at elevated concentrations of free Ca(2+), whereas the inducible isoform binds CaM irreversibly. One of the main structural differences between the constitutive and inducible isoforms is an insert of 40-50 amino acids in the FMN-binding domain of the cNOSs. Deletion of the insert in rat neuronal NOS (nNOS) led to a mutant enzyme which binds CaM at lower Ca(2+) concentrations and which retains activity in the absence of CaM. In order to resolve the mechanism of action of CaM activation we determined reduction potentials for the FMN and FAD cofactors of rat nNOS in the presence and absence of CaM using a recombinant form of the reductase domain. The results indicate that CaM binding does not modulate the reduction potentials of the flavins, but appears to control electron transfer primarily via a large structural rearrangement. We also report the creation of chimaeric enzymes in which the reductase domains of nNOS and flavocytochrome P450 BM3 (Bacillus megaterium III) have been exchanged. Despite its very different flavin redox potentials, the BM3 reductase domain was able to support low levels of CaM-dependent NO synthesis, whereas the NOS reductase domain did not effectively substitute for that of cytochrome P450 BM3.

Amino Acid Substitution↗
PubMed2001

Immunohistochemical localization of guinea-pig leukotriene B4 12-hydroxydehydrogenase/15-ketoprostaglandin 13-reductase.

We have cloned cDNA for leukotriene B4 12-hydroxydehydrogenase (LTB4 12-HD)/15-ketoprostaglandin 13-reductase (PGR) from guinea-pig liver. LTB4 12-HD catalyzes the conversion of LTB4 into 12-keto-LTB4 in the presence of NADP+, and plays an important role in inactivating LTB4. The cDNA contained an ORF of 987 bp that encodes a protein of 329 amino-acid residues with a 78% identity with porcine LTB4 12-HD. The amino acids in the putative NAD+/NADP+ binding domain are well conserved among the pig, guinea-pig, human, rat, and rabbit enzymes. The guinea-pig LTB4 12-HD (gpLTB4 12-HD) was expressed as a glutathione S-transferase (GST) fusion protein in Escherichia coli, which exhibited similar enzyme activities to porcine LTB4 12-HD. We examined the 15-ketoprostaglandin 13-reductase (PGR) activity of recombinant gpLTB4 12-HD, and confirmed that the Kcat of the PGR activity is higher than that of LTB4 12-HD activity by 200-fold. Northern and Western blot analyses revealed that gpLTB4 12-HD/PGR is widely expressed in guinea-pig tissues such as liver, kidney, small intestine, spleen, and stomach. We carried out immunohistochemical analyses of this enzyme in various guinea-pig tissues. Epithelial cells of calyx and collecting tubules in kidney, epithelial cells of airway, alveoli, epithelial cells in small intestine and stomach, and hepatocytes were found to express the enzyme. These findings will lead to the identification of the unrevealed roles of PGs and LTs in these tissues.

15-Oxoprostaglandin 13-Reductase↗
PubMed2001

Keratosis follicularis squamosa (Dohi): a follicular keratotic disorder well known in Japan.

Keratosis follicularis squamosa (KFS) is a keratinizing disorder, which is well recognized in Japan but rarely reported in other countries. KFS is characterized by asymptomatic small scaly patches with a follicular plug that is scattered on the trunk and thighs. It is easily diagnosed by its characteristic appearance that was originally described in Japanese as "lotus leaves on the water". We report a typical case of KFS and review the mainly Japanese literature. We conclude that KFS is a distinct clinical entity of unknown origin. World-wide recognition of this disease should further clarify the prevalence and pathogenesis of this skin condition.

Adult↗
PubMed2001

Trends in the prevalence of atopic dermatitis in school children: longitudinal study in Osaka Prefecture, Japan, from 1985 to 1997.

BACKGROUND: The authors have carried out questionnaire surveys of health symptoms in school children (aged 7-12 years) in Osaka Prefecture, Japan. In this study, the geographical distribution of and trends in the prevalence of atopic dermatitis were evaluated. OBJECTIVES: To assess the relationship between the prevalence of atopic dermatitis in children and the environmental factors, and to estimate future changes of the prevalence of atopic dermatitis. METHODS: A total of seven population surveys were carried out at 2-year intervals between 1985 and 1997 in a total of about 4 million primary school children (460 000-740 000 per survey). RESULTS: The lifetime prevalence of atopic dermatitis increased from 15.0% in 1985 to 24.1% in 1993 but levelled off thereafter. According to the school year, the prevalence was higher in lower-year pupils. However, the prevalence stopped rising earlier in lower-year pupils and began to decrease in 1997 in first- to third-year pupils. The prevalence according to areas was significantly correlated negatively with air pollution and positively with the income index. According to the income classes, the prevalence increased until 1993 but levelled off thereafter in all classes, which reduced the differences among the classes. CONCLUSIONS: The increase of the prevalence of atopic dermatitis in school children stopped in 1993 in Osaka Prefecture, Japan. It is conceivable that the prevalence had reached the saturation level.

Air Pollutants↗
PubMed2001

Serum alpha-subunit levels in patients with pituitary adenomas.

OBJECTIVE: We investigated preoperative and postoperative serum alpha-subunit levels and the alpha-subunit response to TRH in patients with various types of pituitary tumour and correlated the data with histological findings in order to clarify the significance of alpha-subunit measurement in pituitary adenomas. PATIENTS: We examined 59 patients with pituitary tumours (22 with GH cell adenomas, 30 with clinically nonfunctioning adenomas and seven with other tumours) treated at Toranomon Hospital between 1996 and 1998. RESULTS: The basal alpha-subunit level was supranormal in six out of 22 (27%) patients with a GH cell adenoma and in nine out of 30 (30%) patients with a nonfunctioning adenoma. A paradoxical alpha-subunit response to TRH was found in seven out of 22 (32%) patients with a GH cell adenoma. These seven patients also showed a paradoxical GH response to TRH administration. In addition, paradoxical response to TRH was found in eight out of 30 (27%) patients with a clinically nonfunctioning adenoma. In contrast, patients with other types of pituitary tumour showed neither a supranormal alpha-subunit level nor a paradoxical response to TRH. The supranormal alpha-subunit level and the abnormal response to TRH were normalized in both GH cell adenoma and nonfunctioning adenoma patients after successful surgery. Immunohistochemical studies showed alpha-subunit positive cells in 51% of GH cell adenomas or nonfunctioning adenomas and there was a good concordance with the serum alpha-subunit levels in both GH cell adenoma and nonfunctioning adenoma patients. CONCLUSIONS: These findings suggest that supranormal serum alpha-subunit levels are mainly due to hypersecretion by the tumour itself, while the paradoxical alpha-subunit response to TRH is an associated phenomenon in patients with a GH cell adenoma or nonfunctioning adenoma. The alpha-subunit level and the response to TRH may be useful indicators for assessing the operative outcome, especially in nonfunctioning adenoma patients who have no other definite endocrine markers.

Adenoma↗
PubMed2001

A negative component superimposed on event-related potentials during light drowsiness.

The present study examined the nature of the negative shift of event-related potential (ERP) recorded during the fully awake state, wakefulness with minor awareness deficit (light drowsiness) and stage 1 of NREM sleep. The cortical responses evoked by two types of auditory stimuli were recorded in nine subjects at the different levels of consciousness described above. A negative component with peak latency of 250-350 msec, N300, was identified in ERP during light drowsiness but not in the fully awake state. In stage 1a (stage 1 without vertex sharp waves), the amplitude of N300 was higher than that in light drowsiness, and it was higher in stage 1b than in stage 1a. The scalp distribution of N300 was predominantly on the vertex. It also confirmed that the vertex sharp wave evoked during stage 1 is maximal on the vertex and its peak latency is approximately 300 msec. Considering the similarity in scalp distribution and peak latency between N300 and vertex sharp wave, it is possible that these electroencephalogram phenomena are generated by an identical synchronizing mechanism in the brain. We assumed that N300 observed during light drowsiness may be an incomplete product of vertex sharp wave.

Adult↗
PubMed2001

Low-grade renal cell carcinoma arising from the lower nephron: a case report with immunohistochemical, histochemical and ultrastructural studies.

Most renal cell carcinomas (RCC) are composed of clear cells with sinusoid-like vasculatures and originate from the proximal tubule. On the other hand, collecting duct carcinoma (CDC) and chromophobe RCC are thought to originate from the lower nephron. In the present study, we present a case of unusual RCC. The patient was a 68-year-old Japanese woman who had developed general fatigue with hematuria. Computed tomography revealed a left renal tumor suggesting sarcoma. The resected tumor was located in the renal parenchyma, measuring 12 x 10 x 8 cm in size. Histologically, the tumor consisted principally of cuboidal cells forming parallel or radiating arrays, continuous with the spindle-shaped cells. Most parts of the tumor showed hemorrhagic necrosis. Immunohistochemically, tumor cells were positive for high molecular weight cytokeratins, vinculin, vimentin, CD15 and epithelial membrane antigen, and showed affinities with some kinds of lectins. N- and E-cadherins and beta-catenin were diffusely positive in tumor cells. Nuclear positivity for Ki-67 and p53 protein were approximately 2.0 and 1.7%, respectively. Considering its morphological and histochemical natures, this tumor is considered to have originated from the lower nephron, which is unique for a tumor of low-grade malignancy.

Aged↗