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Biomedical subjects

M Osaka

Publications and source records attributed to M Osaka.

At least 55 records · Page 3Linked to original sources
PubMed1997

Nonlinear pattern analysis of ventricular premature beats by mutual information.

The frequency of ventricular premature beats (VPBs) has been related to the risk of mortality. However, little is known about the temporal pattern of occurrence of VPBs and its relationship to autonomic activity. Hence, we applied a general correlation measure, mutual information, to quantify how VPBs are generated over time. We also used mutual information to determine the correlation between VPB production and heart rate in order to evaluate effects of autonomic activity on VPB production. We examined twenty subjects with more than 3000 VPBs/day and simulated random time series of VPB occurrence. We found that mutual information values could be used to characterize quantitatively the temporal patterns of VPB generation. Our data suggest that VPB production is not random and VPBs generated with a higher value of mutual information may be more greatly affected by autonomic activity.

Adult↗
PubMed1996

Specific N-ras mutation in bone marrow within 48 H of 7,12-dimethylbenz[a]anthracene treatment in Huggins-Sugiyama rat leukemogenesis.

7,12-Dimethylbenz[a]anthracene (DMBA)-induced leukemias in Long-Evans rats consistently have an A --> T transversion at the second base of codon 61 in the N-ras gene. This mutation is also detected in the preleukemic stage. To determine when this specific N-ras mutation occurs in the early stages of leukemogenesis, we designed the mutant allele-specific amplification method, which was sensitive enough to detect one mutant cell among 10(6) normal cells. In the study reported here, N-ras mutation was found in bone-marrow cells 2 d after a single DMBA injection and thereafter throughout the preleukemic stage. These results show that DMBA induces a specific N-ras mutation soon after one DMBA injection and that this mutation is probably the first event in DMBA leukemogenesis.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1996

Changes in autonomic activity preceding onset of nonsustained ventricular tachycardia.

BACKGROUND: The triggering role of the autonomic nervous system in the initiation of ventricular tachycardia has not been established. To investigate the relationship between changes in autonomic activity and the occurrence of nonsustained ventricular tachycardia (NSVT) we examined heart rate variability (HRV) during the 2-hour period preceding spontaneous episodes of NSVT. Twenty-four subjects were identified retrospectively as having had one episode of NSVT during 24-hour Holter ECC recording. METHODS: We measured the mean interval between normal heats (meanRR), the standard deviation of the intervals between beats (SD), the percentage of counts of sequential intervals between normal beats with a change of >50 ms (%RR50), the logarithms of low- and high-frequency spectral components (lnLF, lnHF) of HRV for sequential 10-minute segments preceding NSVT. The correlation dimension (CDim) of HRV was calculated similarly for sequential 20-minute segments. We assessed the significance of the time-course change of each marker over the 120-minute period prior to NSVT onset. RESULTS: MeanRR (P < 0.05), lnLF (P < 0.0001), lnHF (P < 0.0001), the natural logarithm of the ratio of LF to HF (ln[LF/HF]; P < 0.05), and CDim (P < 0.05) showed significant time-course changes during that period, while SD and %RR50 did not. MeanRR, lnLF, lnHF, and CDim all decreased prior to the onset of NSVT, whereas ln(LF/HF) increased. We divided the subjects into two groups: one consisting of 12 patients with coronary artery disease; and the second group of 12 patients without known coronary artery disease. Both groups showed significant changes (P < 0.05) of CDim, lnLF, and lnHF preceding the episodes of NSVT. CONCLUSIONS: Changes in the pattern of HRV prior to the onset of episodes of NSVT suggest that changes in autonomic activity may commonly play a role in the triggering of spontaneous episodes of NSVT in susceptible patients. The measured changes suggest a reduction in parasympathetic activity, perhaps in conjunction with an increase in sympathetic activity, may trigger NSVT.

Adult↗
PubMed1995

Developmental changes of alpha 1-adrenergic chronotropic action on human sinus node.

The important role of alpha 1-adrenoceptors in reperfusion ventricular arrhythmia is mentioned in the introduction. However, the present report is concerned with the sinus node. It is speculated that the decreased positive chronotropic action of alpha 1-adrenergic stimulation due to aging may contribute to the development of sick sinus syndrome.

Adolescent↗
PubMed1995

N-ras mutation in 7,12-dimethylbenz[a]anthracene (DMBA)-induced erythroleukemia in Long-Evans rats.

Intravenous injections of 7,12-dimethylbenz[a]anthracene (DMBA) induce erythroblastic leukemia (erythroleukemia) with No.2 trisomy in Long-Evans rats. Activation of some oncogenes such as abl and Ha-ras has been reported to occur in relation to the secondary chromosomal translocations. In the present studies, a consistent type of mutation, A to T transversion in codon 61 of N-ras gene, was found in all of 6 cultured leukemia cell lines and 5 primary leukemias induced by DMBA. The N-ras mutation was also found in bone marrow cells of 2 out of 8 preleukemias. On the contrary, no mutation was observed in Ha- and Ki-ras genes in all leukemias and preleukemias. The consistent occurrence of above N-ras mutation in leukemias indicates that it plays an important role in DMBA-leukemogenesis.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1995

Degradation of DNA in dried tissues by atmospheric oxygen.

Recently, DNA of extinct creatures have been brought into analyses. The difficulty in this field of research is DNA degradation. Oxidative damage is considered to be one of the causes of the DNA degradation. We studied how DNA in dried tissue was affected by atmospheric oxygen using freeze-dried rat liver as a model. In tissues exposed to oxygen, DNA degradation occurred within several months and the amount of 8-hydroxy-2'-deoxyguanosine in DNA rapidly increased. The DNA degradation was inhibited by lipid extraction prior to the exposure to atmospheric oxygen. Purified lambda phage DNA was not affected by oxygen. Cellular DNA and RNA were degraded slowly in nitrogen air. These results suggest that both atmospheric and endogenous oxygens play a role in DNA degradation in dried tissues.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed1995

Alternative splicing of the neurofibromatosis 1 gene correlates with growth patterns and neuroendocrine properties of human small-cell lung-carcinoma cells.

Two distinct transcripts, type I and type II, of the neurofibromatosis I (NFI) gene are generated by alternative splicing in the region corresponding to the gene's GTPase-activating protein-related domain (GRD). Relative expression levels of these 2 transcripts were previously correlated to neural differentiation. Since small-cell lung carcinoma (SCLC) often exhibits neuroendocrine properties, we analyzed the type-I to type-II mRNA ratio in 15 SCLC cell lines, using reverse transcriptase and polymerase chain reaction methods. The type-I mRNA was predominant in 10 cell lines; 8 of them grew as floating aggregates in culture and had high L-dopa decarboxylase (DDC) activity. The other 5 lines predominantly expressed type-II mRNA, adhered to the culture substrate, and expressed low or undetectable levels of neural cell-adhesion molecule (NCAM) antigen and DDC activity. N2+, one of the subclones of NCI-N417 cells, exhibited a higher type-I to type-II ratio after the cells had adhered to a laminin-coated plate and had emitted neurite-like processes. These findings provide evidence that alternative splicing patterns of NFI mRNA correlate with the mechanisms that regulate the growth patterns and neuroendocrine properties of SCLC cells in vitro.

Alternative Splicing↗
PubMed1995

Contribution of chromosome 9p21-22 deletion to the progression of human renal cell carcinoma.

To investigate the possible role of genomic aberrations of chromosome 9p21-22 in the tumorigenesis of human renal cell carcinoma (RCC), 10 RCC cell lines, 55 primary RCCs and 5 metastatic lesions were studied by Southern blotting and polymerase chain reaction-based analysis. Nine of 10 RCC cell lines showed a homozygous deletion of MTSI/CDKN2/(p16), while only 1 in 55 primary tumors had this deletion. Loss of heterozygosity on 9p21-22 was observed in 5 of 10 informative primary RCCs from patients with metastasis, but in only 4 of 31 informative tumors (13%) without metastasis (P = 0.025). Futhermore, 3 of 5 metastatic tumors (60%) showed hemi- or homozygous deletion of MTSI/CDKN2. These results indicate that the 9p21-22 deletion may be a relatively late event in RCC tumorigenesis and could be associated with RCC metastasis.

Alleles↗
PubMed1994

[Working memory capacity related to reading: measurement with the Japanese version of reading span test].

The efficiency of working memory capacity was measured with the Japanese reading span test (Japanese RST), which was developed based on the Carnegie-Mellon RST (Daneman & Carpenter, 1980). The correlation between the Japanese and the CMU RST was found to be highly significant. The present Japanese RST seems to predict reading efficiency in the same way as does the CMU RST. The Japanese RST was found to be correlated not only with memory span but with reading comprehension. However, it was not correlated with existing verbal intelligence tests.

Adult↗
PubMed1994

[Endourologic treatment of the upper urinary tract obstruction in the advanced cancer patients].

88 cancer patients with an upper urinary tract obstruction were endourologically treated. The obstructions were caused by metastasis or invasion of cancer in all patients. First we tried to insert a ureteral stent catheter (STENT). When it failed percutaneous nephrostomy (PCN) was performed. Initially 69 and 19 patients were treated by STENT and PCN, respectively. Of 69 patients with STENT, 13 received PCN later. The average survival of all patients after treatment was 5.7 months. About 60% of the patients were discharged from hospital. The patients treated by STENT and PCN survived for 5.4 months and 6.7 months in average. The STENT was changed 1.8 times on the average in all patients. 79% of the patients who had been treated by STENT experienced only one or two times of STENT changes before dying. Patency period of inserted STENT was studied. On the average the STENT occluded after 72.4 days. The patent period of STENT was longer in the patients group of prophylactic STENT insertion for hydronephrosis. The period was shorter in the patients who showed gross hematuria at the time of surgery. Patent period of STENT was not related to STENT size. Although survival was not so long, over 60% of the patients were able to return to their homes. Endourologic treatment of urinary obstruction was performed in only 6 patients in 1985. The number of such cases has been increasing gradually and currently 20 patients are treated annually. It is supposed that there are many more cancer patients with urinary tract obstruction in their end-stage.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Correlation dimension of heart rate variability: a new index of human autonomic function.

Correlation dimension analysis (CDA) of spontaneous heart rate variability in humans was performed with the use of autonomic blocking agents (propranolol and atropine) and postural change, and was compared with heart rate power spectral analysis (HRPSA). The correlation dimension was increased by the suppression of sympathetic activity and decreased by the suppression of parasympathetic activity. Atropine abolished the correlation dimension and the low- and high-frequency components of HRPSA. With a postural change from supine to standing, the low- to high-frequency power ratio was significantly increased, indicating the augmentation of sympathetic activity or the reduction of parasympathetic activity, or both. Thus, it was suggested that a postural change from supine to standing causes the predominance of sympathetic activity. As this postural change decreased the correlation dimension, it was also indicated that the predominance of sympathetic activity may decrease the correlation dimension. CDA was superior to HRPSA in that the former method provided a measure of the effect of propranolol on the heart in the supine position, which could not be evaluated by the latter method. Thus, CDA of heart rate variability is a useful non-invasive tool for evaluating the autonomic balance.

Adult↗
PubMed1992

Blood pressure changes following extracorporeal shock wave lithotripsy for urolithiasis.

Hypertension after extracorporeal shock wave lithotripsy (ESWL) has been a controversial subject. Changes in blood pressure were studied in 262 patients (mean age 47.8 years) 18.6 months after ESWL. According to World Health Organization criteria the number of patients who showed a decrease exceeded those who showed an increase in blood pressure. The patients who have been on antihypertensive therapy showed a significantly greater decrease in blood pressure than those without medication. Of 192 normotensive patients diastolic pressure increased 1.2 mm. Hg and 2 (1.0%) had hypertension 18.4 months after ESWL. Annualized increase in diastolic pressure and new onset of hypertension were calculated to be 0.78 mm. Hg and 0.65%, respectively. Significant elevation of diastolic pressure was noted in the patients who received a larger number of shock waves. Blood pressure should be carefully followed after ESWL especially in patients who have been treated by a greater number of shock waves.

Adult↗
PubMed1992

Effect of memory set-size upon event related potentials for concrete and abstract kanji stimuli.

Event related potentials (ERP) and reaction times (RT) were recorded during the performance of memory-retrieval tasks using the Japanese kanji characters. P300 latency and RT increased as the memory set-size increased. The slope differences between RT and P300 latency were larger for stimuli when concrete kanji were used than when abstract kanji were used. This suggests that, in memory search, the 20 subjects were likely to employ direct lexical access when processing concrete kanji and likely to use phonetic coding when processing abstract kanji.

Arousal↗
PubMed1988

Primary biliary cirrhosis with fibrosing alveolitis.

A 65-year-old case diagnosed as primary biliary cirrhosis without definite signs of Sjögren's syndrome at age 62 developed interstitial lung disease, which was clinically, histologically, radiographically, and scintigraphically compatible with fibrosing alveolitis. Analysis of the cells in bronchoalveolar lavage fluid revealed, however, increased proportions of not only neutrophils but also lymphocytic cells, which were predominant. This case should focus attention on the association of primary biliary cirrhosis and fibrosing alveolitis.

Aged↗