PubMed Health⌕ Search

Biomedical subjects

K Yoshikawa

Publications and source records attributed to K Yoshikawa.

At least 19 recordsLinked to original sources
PubMed1995

The loss of 40-kDa chromosomal protein in tuberous sclerosis lesions.

Tuberous sclerosis is an genetic disease characterized by systemic hamartomas. Some of the cultured cells derived from tuberous sclerosis show the distinct chromosomal disarrangement and abnormal cell division. To detect the proteins responsible for this phenomenon, we investigated many nuclear components related to cell division. 40-kDa protein (p40) recognized by one monoclonal antibody M108, which was present in nucleus, chromosomes and cytoplasm of many vertebrate culture cells, significantly decreased in the tuberous sclerosis cells. Immunoblot analysis revealed that in all the fractions the quantity of p40 of severe tuberous sclerosis cells was approximately 4 times less than p40 in normal fibroblasts.

Antibodies, Monoclonal↗
PubMed1995

[3H]9-Methyl-7-bromoeudistomin D, a caffeine-like powerful Ca2+ releaser, binds to caffeine-binding sites distinct from the ryanodine receptors in brain microsomes.

[3H]9-Methyl-7-bromoeudistomin D ([3H]MBED), the most powerful Ca2+ releaser from sarcoplasmic reticulum, specifically bound to the brain microsomes. Caffeine competitively inhibited [3H]MBED binding. [3H]MBED binding was markedly blocked by procaine, whereas that was enhanced by adenosine-5'-(beta,gamma-methylene)triphosphate. The Bmax value was 170 times more than that of [3H]ryanodine binding. The profile of sucrose-density gradient centrifugation of solubilized microsomes indicated that [3H]MBED binding protein was different from [3H]ryanodine binding protein. These results suggest that there are MBED/caffeine-binding sites in brain that are distinct from the ryanodine receptor and that MBED becomes an essential molecular probe for characterizing caffeine-binding protein in the central nervous system.

Adenosine Triphosphate↗
PubMed1995

Positively charged surface induces discontinuous transition for the high order structure in duplex DNA.

Interaction of DNA molecules with solid surface was studied with single molecular observation by use of fluorescence microscopy. Drastic change in the conformation of DNA chain was induced by the interaction with the positively charged surface. It was found that unfolded DNA chain in aqueous solution changes into compacted globule accompanied with the adsorption onto the positively charged surface. A brief discussion is represented concerning the mechanism of the transition from the physico-chemical point of view.

Antioxidants↗
PubMed1995

Arrest of cell growth by necdin, a nuclear protein expressed in postmitotic neurons.

Necdin is a 325 amino acid residue protein localized to the nuclei of postmitotic neurons, which withdraw permanently from the cell cycle. To examine whether necdin confers the postmitotic phenotype, necdin cDNA was stably transfected into NIH3T3 cells, in which the protein was conditionally expressed using a eukaryotic lac repressor-operator expression system. When the transfectants were induced to express ectopic necdin, cell growth was arrested without appreciable reduction in cell viability. The expressed necdin molecule was localized to the nuclei of the transfectants. These results suggest that necdin is a nuclear factor that governs the permanent arrest of cell growth of postmitotic neurons during development of the nervous systems of vertebrates.

3T3 Cells↗
PubMed1995

Determination of a necdin cis-acting element required for neuron specific expression by using zebra fish.

To determine cis-acting elements required for neuron specific expression of a necdin gene, we tried to use zebra fish assay system in vivo instead of cell lines in vitro. Various expression vectors carrying upstream sequences of necdin gene fused to MEKA (lacZ) gene as a reporter were injected into fertilized zebra fish embryos and then the expression of the reporter gene was analyzed by the whole mount immunochemical method. No promoter activity was obtained with a construct carrying sequence from -63 to +63 of the necdin gene, while promoter activity with preferential skin expression was obtained with a construct having sequence from -86 to +28. Further upstream sequence from -173 to +28 exhibited neuron specific expression as well as that from -845 to +63. These results indicate that a cis-acting element responsible for neuron specific expression is located in an 87bp sequence from -173 to -87 of necdin gene.

Animals↗
PubMed1995

Diaminoalkanes with an odd number of carbon atoms induce compaction of a single double-stranded DNA chain.

We have performed direct observations on the conformational change of a single double-stranded T4 DNA molecule induced by diaminoalkanes, NH3+(CH2)nNH3+(n = 1-6), by use of fluorescence microscopy. It was found that diamines with three and five methylene groups show a significant effect on the compaction of individual single DNA molecules. On the other hand, diamines with two, four and six methylene groups are not effective in the compaction of DNA. Such a drastic difference in the action of diamines suggests that not only the number of charge but also the length between the amino groups in the diamines plays an essential role in their interactions with DNA.

Alkanes↗
PubMed1995

Chronic effect of oral mexiletine administration on left ventricular contractility in patients with congestive heart failure: a study based on mitral regurgitant flow velocity measured by continuous-wave Doppler echocardiography.

The long-term effect of mexiletine on left ventricular (LV) contractility in patients with congestive heart failure is not clear. The authors therefore measured LV contractility before and after continuous oral administration of mexiletine in patients with congestive heart failure accompanied by mitral regurgitation (MR) using Doppler echocardiography. The study population consisted of 8 patients with congestive heart failure (6 due to dilated cardiomyopathy and 2 due to old myocardial infarction) accompanied by significant functional MR who had more than 1000 ventricular premature contractions (VPCs) per day or Class IV Lown classification arrhythmias before mexiletine administration. The LV contractility was evaluated by calculating a Doppler-derived index, the rate of increase in LV pressure during the isovolumic contraction time (ICT delta P/delta t), which has been confirmed to be nearly equal to LV Max dP/dt. The increase in LV pressure (delta P) between 1 and 3 m/sec of the MR flow velocity as measured by continuous-wave Doppler echocardiography was calculated using the simplified Bernoulli's equation, and ICT delta P/delta t was derived by dividing delta P by the time required for this change. The left ventricular ejection fraction and the left ventricular and left atrial dimensions also were measured by echocardiography. These parameters were obtained before and after 2 to 4 weeks of daily oral administration of mexiletine 300 mg. Values of ICT delta P/delta t were 640 +/- 202 mm Hg/sec and 650 +/- 210 mm Hg/sec before and after mexiletine administration, respectively, showing no change.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1995

A case of primary Hodgkin's disease of the stomach.

A case of primary Hodgkin's disease, a lymphocyte-predominant entity, occurring in the stomach is described. The patient was a 37-year-old man who complained of general fatigue. Endoscopic biopsy revealed gastric malignant lymphoma. Subtotal gastrectomy and postoperative chemotherapy following a modified CHOP regimen were performed. The patient has been free of recurrence during a follow-up period of 15 months. The preoperative diagnosis of gastric Hodgkin's disease is difficult. Thus far, of 100 cases of gastric Hodgkin's disease reported in Japan, only 3 were diagnosed correctly preoperatively. We also misdiagnosed our case, as B cell type malignant lymphoma, preoperatively. The final diagnosis of Hodgkin's disease of the stomach was made on the basis of histopathological and immunohistochemical examinations. Hodgkin's disease of the stomach is rare, and there are histologically similar diseases; Ki-1 lymphoma, adult T cell lymphoma, malignant histiocytosis, and infectious monocytosis. Careful diagnosis is essential thus for Hodgkin's disease of the stomach.

Adult↗
PubMed1995

Saponins from Albizia lebbeck.

Three main saponins named albiziasaponins A, B, and C were isolated from the barks of Albizia lebbeck. Their structures were established through spectral analyses as acacic acid lactone 3-O-beta-D-xylopyranosyl-(1-->2)-alpha-L-arabinopyranosyl-(1-->6)- beta-D-glucopyranoside, 3-O-beta-D-glucopyranosyl-(1-->2)-O-[alpha-L-arabinopyranosyl-(1-- >6)]- beta-D-glucopyranoside and 3-O-beta-D-xylopyranosyl-(1-->2)-alpha-L-arabinopyranosyl-(1-->6)- O- [beta-D-glucopyranosyl-(1-->2)]-beta-D-glucopyranoside.

Carbohydrate Conformation↗
PubMed1995

Genotoxic effect of griseofulvin in somatic cells of Drosophila melanogaster.

Griseofulvin (GF), a carcinogenic spindle poison, was tested in two types of somatic-cell assays of Drosophila melanogaster, one of which detects the induction of DNA damage and the other mutation/mitotic recombination. In both assays, GF was fed to tester larvae and genetic endpoints examined after emergence. In the wing spot test, trans-heterozygous flies carrying mwh and flr3 wing-hair mutations produced both significant and dose-dependent increases in the frequency of mwh single spots over the control level but no increase of twin spots. In the DNA repair test, double-mutant larvae carrying both mei-9(a) (excision repair-defective) and mei-41(D5) (postreplication repair-defective) mutations showed hypersensitivity to killing by GF compared with their DNA repair-proficient counterparts, suggesting that GF caused potentially lethal DNA damages which were efficiently repaired by the DNA repair-proficient but not -defective larvae. These lines of evidence clearly demonstrate that GF is genotoxic in somatic cells of Drosophila. It is noted that (1) GF-fed larvae showed a developmental delay and (2) surviving adult flies had morphological abnormalities in their eyes and wings.

Animals↗
PubMed1995

The in vivo-in vitro replicative DNA synthesis (RDS) test with hepatocytes prepared from male B6C3F1 mice as an early prediction assay for putative nongenotoxic (Ames-negative) mouse hepatocarcinogens.

To assess the efficacy of the in vivo-in vitro hepatocyte replicative DNA synthesis (RDS) test as a short-term assay, 41 putative nongenotoxic (Ames-negative) mouse hepatocarcinogens, as well as 31 noncarcinogens, were examined using male 8-week-old B6C3F1 mice and an in vitro [methyl-3]thymidine-incorporation technique. Animals were exposed to the maximum tolerated dose (MTD) and 1/2 MTD of each chemical by gavage and after 24, 39 or 48 h, hepatocytes were prepared with a collagenase-perfusion technique. Assessment of the distribution of spontaneous RDS in a total of 337 control mice gave an average incidence of 0.15 +/- 0.08% within the range of 0 to 0.39% (mean +/- 3 x SE) with a 99.7% probability. Values of 0.4% or more for RDS incidences induced by test samples were therefore judged as indicating a positive response in our RDS test. Under the experimental conditions applied, 32 of 41 putative nongenotoxic hepatocarcinogens gave clear positive responses (positive sensitivity: 78%), and of 31 noncarcinogens 25 samples gave negative responses (negative specificity: 81%), thus giving an overall concordance for the RDS test with long-term findings of 79%.

Administration, Oral↗
PubMed1995

Neuromagnetic measurements of the human primary auditory response.

The spatio-temporal organization of the human primary auditory response (N19 and P30) was determined by analyzing magnetic fields from the right hemisphere evoked by monaural clicks to the left ear. The magnetic response consisted of peaks corresponding to electrical N19 (N19m) and P30 (P30m) within 40 msec after stimulation. However, the onset of electrical N19 occurred 5-9 msec earlier than that of the magnetic counterpart. Furthermore, the relative amplitude of N19 and P30 (N19/P30) was larger (more than 1) than that (about 0.5) of N19m and P30m (N19m/P30m). The findings suggest an additional contribution from a subcortical source for electrical N19. The estimated equivalent sources for N19m and P30m were localized at the postero-medial part of Heschl's gyrus (the primary auditory cortex). Furthermore, the dipole orientation of N19m was directed postero-ventrally and that of P30m was in the opposite direction, which is compatible with the anatomy of the supratemporal primary auditory cortex. These results resolve a long standing controversy of cortical vs. subcortical structures as the generators of the N19.

Auditory Cortex↗
PubMed1995

Effect of donor age on the phosphorylation of the retinoblastoma gene product in cultured human keratinocytes.

The retinoblastoma gene product (pRB) is a tumor suppressor protein. Recently, it has been shown that the phosphorylation of pRB is necessary for progression from G1 to S phase in a variety of cells. In a word, the phosphorylation of pRB accelerates cell growth. In this study, we examined the phosphorylation status of pRB in normal human keratinocytes obtained from donors aged from 1 year to 71 years. The cells of old donors (61-71 years old) presented the more dense hypophosphorylated pRB band than cells of young donors (1-19 years old). Densitometric measurement showed that 42.3% +/- 4.8% of the total pRB was hypophosphorylated in cells of young donors, while 58.1% +/- 6.9% was hypophosphorylated in those of old donors. Results indicate that more pRB is hypophosphorylated in cells of old donors. The phosphorylated status of pRB might be related to the loss of growth fraction in human keratinocytes of old donors.

Adult↗
PubMed1995

Multichannel detection of magnetic compound action fields with stimulation of the index and little fingers.

Magnetic compound action fields (CAFs) over the right arm were measured from 63 sensor positions with two 7-channel SQUID gradiometer systems following electrical stimulation of the index and little fingers as well as the ring finger separately. The wave forms of the CAFs were primarily biphasic, corresponding to the depolarization and repolarization currents of the stimulated nerves. Maximum amplitudes of the CAFs were 60-140 fT for the index finger stimulation and 40-90 fT for the little finger stimulation. The field mapping of the CAFs revealed a propagating quadrupolar pattern with different distributions for the index and little fingers. The results agree with the anatomical location of the median and ulnar nerves for the index and little finger stimulation respectively. The isofield maps, due to ring finger stimulation, showed complex patterns as a result of simultaneous activation of the median and ulnar nerves. By comparing the amplitudes of the maxima of the CAFs due to index finger stimulation with those after median nerve stimulation at the wrist, the numerical ratios of the constituent digital nerve fibers for the index finger within the median nerve at the wrist were estimated. The ratios of 0.14-0.41 (mean 0.27), determined with measurement of the CAFs, are fairly consistent with those calculated from the reported histological data.

Adult↗
PubMed1995

Microvessel quantitation in invasive breast cancer by staining for factor VIII-related antigen.

The clinical importance of microvessel quantitation as a prognostic indicator in invasive breast cancer was examined. This study included 155 patients with invasive breast cancer, with a median follow-up of 82 months. Microvessels were identified by immunohistochemical staining for factor VIII-related antigen in formalin-fixed, paraffin-embedded primary tumours. For each tumour, microvessels were counted within a 200 x magnification field in the area of highest microvessel density. Microvessel counts (MVCs) had no correlation with tumour size, lymph node status or histological grade. When patients were classified by MVC, higher counts were associated with shorter disease-free survival and overall survival (P < 0.025 and P < 0.01 respectively). Multivariate analysis showed that MCV is an independent prognostic factor. Microvessel quantitation may be a useful predictor for identifying breast cancer patients at high risk for relapse and death.

Breast Neoplasms↗
PubMed1995

Acute Budd-Chiari syndrome due to inferior vena cava occlusion following blunt trauma.

Inferior vena cava (IVC) thrombosis or obstruction is a complication rarely associated with blunt trauma. We present a case of IVC thrombo-occlusive lesion with both hepatic and renal failure which developed after a thoracoabdominal blunt trauma. Direct thrombectomy and patch cavoplasty were successfully carried out under deep hypothermia using cardiopulmonary bypass.

Acute Disease↗
PubMed1995

Perceptual changes accompanying controlled blocking of cutaneous afferents are related to somatosensory evoked potentials.

We examined the effect of local anaesthesia of the skin on somatosensory evoked potentials (SEPs) and psychophysical magnitude estimates for a constant intensity air-puff stimulation (7 kg.cm-2) in 23 normal subjects. Before and after intradermal injection (0.1 ml of 1% xylocain) to the tip of the right index finger, magnitude estimations for the four modalities of skin sensation (touch, pressure, pain and vibration), and SEPs were successively examined at 4-10 min interval until complete sensory and SEP recovery. The time course of sensory recovery was similar for the first three modalities and vibration sense was little affected by local anaesthesia. Immediately after anaesthesia, SEPs either abolished or decreased in amplitude. Thereafter amplitudes increased and peak latencies decreased with the elapsed time. Comparison of the regression lines for the amplitude of P45-N60 component or the time-integrals of N20 and N35 components with that of psychophysical estimates revealed steeper slopes for psychophysical data: 0.4-0.7 for neural versus 1.4-1.7 for psychophysical data. These relations between SEPs and psychophysics following local anaesthesia bear a close parallel to those observed in our previous studies in a normal condition with increasing stimulus intensity. The SEP latencies for N20, P27 and N35 components were better correlated with recovery from anaesthesia. Direct comparisons of SEP measures with subjective magnitudes produced significant correlations for the three modalities of sensation in which again latencies are better correlated than amplitides or time-integrals.

Adolescent↗