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Biomedical subjects

M Yuasa

Publications and source records attributed to M Yuasa.

At least 37 records · Page 2Linked to original sources
PubMed1997

The inhibitory effect of vitamin E on K-ras mutation at an early stage of lung carcinogenesis in mice.

In this study, we investigated the effect of vitamin E on the activation of the K-ras oncogene with a 61st codon A-->T mutation at an early stage of urethane-induced lung carcinogenesis in mice. Thirty days after urethane injection, the K-ras mutation was detected in 64% of lung samples tested by mutant-allele-specific amplification. The consumption of a supplemented diet with about 20-times more vitamin E than the control diet, only during the promotion phase or during both the initiation and promotion phases of lung carcinogenesis, reduced the frequency of the mutation to 36 and 18%, respectively. Also, vitamin E suppressed the level of proliferating cell nuclear antigen as a marker of cell proliferation in the lungs of mice treated with urethane. These results support the notion that vitamin E is a useful chemopreventive agent against lung cancer.

Animals↗
PubMed1997

[Fluorine-18 labeled 6-fluoro-L-dopa: systematization and evaluation of its usefulness].

6-[18F]Fluoro-L-dopa (L-3,4-dihydroxy-6-[18F]fluorophenylalanine; 6-[18F]FDPA) is useful to assess presynaptic dopamine metabolism in central nervous system. In this paper, we report on the usefulness of the 6-[18F]FDOPA synthesis system developed for the routine synthesis. This system consists of the 6-[18F]FOPA synthesis and the separation units in conjunction with controller using a personal computer. The synthesis time of 6-[18F]FDOPA was 73 minutes. The typical yield and specific activity were 1.4-2.4 GBq and 244-270 MBq/mumol at the end of synthesis, respectively, under the irradiation condition of 50 microA for 130 minutes. The radiochemical yields of 6-[18F]FDOPA were 31.3-38.7% based on the [18F]acetylhypofluorite, and the results were affected with the condition of potassium acetate (AcOK) to produce gaseous [18F]acetylhypofluorite. This system is useful for the routine production of 6-[18F]FDOPA because of its high yield and high specific activity while maintaining AcOK in good condition, and decreasing the radiation exposure for chemist.

Brain↗
PubMed1996

Non-decay type fast-setting calcium phosphate cement: setting behaviour in calf serum and its tissue response.

Non-decay type fast-setting calcium phosphate cement (nd-FSCPC) was evaluated in terms of its setting behaviour in calf serum and its tissue response to investigate the feasibility of its clinical use in surgical applications. Non-decay type cements were prepared by adding various amounts of sodium alginate to the liquid phase of base cements, fast-setting calcium phosphate cement (FSCPC) and conventional calcium phosphate cement (c-CPC). Cement pastes were immersed in serum at 37 degrees C immediately after mixing, and decay behaviour, setting time and mechanical strength were measured to evaluate the possibility of their use in surgical applications. Also, nd-FSCPC was implanted into rat subcutaneous tissue for the initial evaluation of biocompatibility of this potential bioactive cement. nd-FSCPC set in approximately 6-7 min in serum, even when the cement paste was immersed in the serum immediately after mixing, whereas c-CPC and FSCPC decayed completely upon immersion. nd-FSCPC transforms to hydroxyapatite (HA) within 24 h and shows a diametral tensile strength of approximately 4-5 MPa. As a result of transformation to HA, nd-FSCPC showed excellent tissue response when implanted subcutaneously in rats. We conclude that nd-FSCPC has good potential value for use in orthopaedics, plastic and reconstructive surgery, and oral and maxillofacial surgery, where the cement is exposed to blood.

Animals↗
PubMed1996

[Clinical studies for venogenic impotence with color Doppler ultrasonography--evaluation of resistance index of the cavernous artery].

BACKGROUND: Pharmaco-dynamic infusion cavernosometry and cavernosography (pharmaco-DICC) is essential for diagnosis of venogenic impotence, however it is so invasive. On the other hand, color Doppler ultrasonography is non-invasive and has become one of the useful diagnostic methods for arteriogenic impotence. And there are some reports evaluating whether venogenic impotence can be diagnosed using color Doppler ultrasonography. In this study, we investigated whether the resistance index (RI) could be useful for screening for venogenic impotence. METHODS: We performed color Doppler ultrasonography in 49 patients who had shown negative responses to an intracavernous injection of 20 mcg of prostaglandin E1 (PGE1). They previously underwent pharmaco-DICC and were diagnosed venogenic impotent when the maintenance flow rate was equal to or more than 20 ml/min. In 49 patients, 17 patients had DICC normality, while 32 patients had corporal leakages. After an intracavernous injection of 20 mcg of PGE1, we performed color Doppler ultrasonography, and measured peak systolic velocity (PSV) and end diastolic velocity (EDV) in the cavernous artery. RI was calculated as follows. RI = (PSV-EDV)/PSV We adopted the RI value near to 1 as the case's RI from two RI values of bilateral cavernous arteries, and compared RI values with the results of pharmaco-DICC. RESULTS: RI range in patients with normal DICC results was 0.895 +/- 0.092 (0.70-1.00), while RI range in patients with corporal leakages was 0.742 +/- 0.095 (0.55-0.97). RI values in patients with corporal leakages were significantly lower than those in patients with normal DICC results although there was some overlap in each group. From receiver-operating-characteristic curve (ROC curve) of the correlation between sensitivity and specificity at various RI values compared with DICC results, the RI cut off values were set up at 0.75 and 0.90, and classified the patients into 3 group according to their RI cut off values. In 10 patients with 0.9 < RI, 9 patients (90%) had DICC normality. In 17 patients with 0.75 < RI < or = 0.9, 7 patients had DICC normality while 10 patients had corporal leakages. In 22 patients with RI < or = 0.75, 21 patients (95.5%) had corporal leakages. CONCLUSION: We consider without carrying out pharmaco-DICC that patients with 0.9 < RI were not venogenic impotent, while patients with RI < or = 0.75 had corporal leakages. Pharmaco-DICC will remain essential only in patients with 0.75 < RI < or = 0.9.

Adult↗
PubMed1996

[A study of coping in middle-aged women with urinary incontinence].

The purpose of this study is to clarify the coping patterns of women with urinary incontinence (UI) who visited an incontinence special unit. Nineteen patients ranging from 42 to 86 in age were interviewed. When they had met the accidents or daily occurrences with UI, their attitudes toward UI were classified into six coping patterns. They were "managing of UI", "keeping UI in secret", "asking for medical treatment for UI", "asking for support", "accepting UI as a fact or being resigned to UI, and "avoiding the fact with UI". All these six coping patterns reflect their desire to keep themselves in normal status. They concentrated themselves on maintain the normalization so as to keep their self-esteem from the threat of UI.

Adaptation, Psychological↗
PubMed1995

Biliary excretion of copper, metallothionein, and glutathione into Long-Evans Cinnamon rats: a convincing animal model for Wilson disease.

Long-Evans Cinnamon (LEC) rats, characterized by a gross accumulation of hepatic Cu and the spontaneous onset of hepatitis, have been established to be an animal model for Wilson disease. They were used to estimate the relationships among copper (Cu), metallothionein (MT), and reduced glutathione (GSH) in biliary excretion in this study. Even though a huge amount of MT existed in the LEC rat liver (5016 micrograms/g liver) compared to that (63 micrograms/g liver) of controls (Fischer rats), the biliary excretion of MT (65 ng/ml bile) did not reflect the accumulated MT level in LEC rats. It seems likely that MT does not excrete intrinsically into the bile. Biliary excretion of Cu (0.17 microgram/ml) in LEC rats was significantly lower than that (0.57 microgram/ml) in Fischer rats. The difference in biliary excretion of GSH between the two groups was significant but slight. The reduced excretion of GSH into bile in LEC rats may be due to increased hepatic gamma-glutamyltransferase but not to hepatic GSH levels. There were no differences in biliary potassium and inorganic phosphorous between the two groups. On the other hand, excretion of lysosomal enzymes such as beta-N-acetylglucosaminidase into bile was much lower in LEC rats (15.6 units/liter) than in controls (42.5 units/liter). The defective biliary excretion of Cu may be due to impaired lysosomal exocytosis, rather than canalicular membrane impairment. The LEC rat is very useful for research into the dynamics of metal excretion via the hepatobiliary system.

Acetylglucosaminidase↗
PubMed1995

Nursing in Japan: caregivers of elderly family members with dementia.

1. The difficulties that caregivers of elderly family members suffering from dementia confronted are divided into five categories: incomprehensible situations, strange behavior, deterioration of dementia, trouble or inconvenience caused by demented behavior, and remarks vis-a-vis support network. 2. The considerable differences among caregivers of elderly persons suffering from dementia, in terms of problems faced and methods of coping, existed in beginning and awakening stages. 3. Nurses must assess which stages of the developmental process families are going through to implement effective nursing interventions that vary between the two stages.

Aged↗
PubMed1995

[Evaluation of cavernous artery by color Doppler ultrasonography--significance of ultrasonic beam angle].

Penile Doppler ultrasonography is widely accepted as an essential examination in the diagnosis of impotence. However, measurement blood flow velocity using Doppler ultrasonography may be subject to some errors. We performed color Doppler ultrasonography in 63 patients with normal penile vascular function as diagnosed using positive responses to intracavernous pharmacological stimulation. We compared the Doppler measurement results of the 126 cavernous arteries and the ultrasonic beam angles. We used a Hitachi EUB 515, a sonographic probe of 7.5 MHz, a sampling width of 0.8 mm, a sampling depth of 1 mm, and a wall motion filter was not used. Ultrasonic beam angles were 5 to 77 degrees. The mean peak systolic velocity and end diastolic velocity values were 40. 0 cm/s and 3.9 cm/sec, respectively. The peak systolic velocity and end diastolic velocity values remained stable regardless of the ultrasonic beam angles (Kruskal-Wallis test, p = 0.56, p = 0.70). However, the variance of values became greater when the ultrasonic beam angles was larger than 55 degrees in the case of peak systolic velocity (F test, p < 0.05) and 50 degrees in the case of end diastolic velocity (F test, p < 0.05), indicating a reduction in reliability. Resistance index variance was significantly higher when ultrasonic beam angle exceeds 50 degrees (F test, p < 0.05). We believe that we should accept only those cavernous artery peak systolic velocity measurements as reliable when the ultrasound beam angle is less than 55 degrees.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

[New nocturnal penile tumescence recorder].

BACKGROUND: Records of nocturnal penile tumescence are still important test and necessary to distinguish organic impotence from psycogenic impotence. METHODS: We developed the nocturnal penile tumescence recorder with a disposab indiumgallium straingauge, and we examined its clinical usefulness for volunteers with normal erectile function. RESULTS: The results were that the indium-gallium straingauge had almost the same resistance change with extension, and that it showed almost the same resistance value at respective circumferences with consecutively ten times measurements. Only two of thirty-nine volunteers experienced the snapping of the indium-gallium strain-gauge. None of the volunteers complained of discomfort during measurements. The nocturnal penile tumescence of five volunteers were recorded with a conventional mercuric straingauge and a newly developed indium-gallium straingauge simultaneously, and there were no significant differences between the results of the two materials. This recorder is very simple to manage, and the softwares for preservation of data and making graph are also simple. This new straingauge is clean and dose not require maintenance because of the disposable use. CONCLUSION: We concluded that this recorder system was clinically useful for t examination of nocturnal penile tumescence.

Circadian Rhythm↗
PubMed1994

Defects of immune cells in the senescence-accelerated mouse: a model for learning and memory deficits in the aged.

We investigated immune characteristics of SAMP8 mice that have early learning and memory deficiencies and a short life span accompanied by normal growth and compared them to those of SAMR1 mice that have a normal aging process. The indexes of immune responsiveness used were natural killer (NK) cell activity, in vitro anti-SRBC (sheep red blood cells) antibody responses, cell proliferation, and interleukin 2 (IL-2)-producing activity in response to concanavalin A of spleen cells. As early as 2 months after birth, SAMP8 mice showed markedly low activity for all the indexes that was not due to a delay of their development. Endogenous NK cell activity in SAMP8 mice remained low or at the background level for a few months, but the trace level of this activity increased after treatment with an immune potentiator of polyinosinic-polycytidylic acid. Because the number of cells bearing an NK cell marker in SAMP8 mice was comparable to that for SAMR1 mice, the low NK cell activity found for SAMP8 mice may not be caused by a low number of precursor cells but by defects in the lytic mechanism or low competence. Flow cytometry analyses showed that the size of the lymphocyte fraction in the spleen is the same for both strains and that T cell fractions, especially of CD4+ T cells in SAMP8 mice are smaller than in SAMR1 mice. In contrast, a B cell fraction was somewhat larger in SAMP8 mice. Together with the fact that the spleen cells of both strains equally stimulated allogeneic T cells in the mixed lymphocyte reaction, the low helper T cell activity in antibody responses, even under the condition of cell-number equivalence, indicates a qualitative defect of CD4+ T cells in SAMP8 mice. This defect probably is closely related to the low endogenous activity of NK cells.

Aging↗
PubMed1994

Evidence that Escherichia coli ubiA product is a functional homolog of yeast COQ2, and the regulation of ubiA gene expression.

The Escherichia coli ubiA gene coding for 4-hydroxy benzoate octaprenyl transferase is thought to be a key enzyme of ubiquinone biosynthesis. Strains with ubiA disrupted were constructed by chromosomal gene replacement with the chloramphenicol resistance gene. The respiration-defective phenotype of the ubiA mutant was complemented by expression of the COQ2 gene encoding the 4-hydroxy benzoate hexaprenyl transferase of Saccharomyces cerevisiae and such strains produced ubiquinone-8. This strongly supports the idea that COQ2 catalyzes the same enzymatic reaction with UbiA and the substrate specificity of COQ2 is broad. Study of the expression of ubiA using an ubiA-lacZ fusion system showed that the ubiA expression was catabolite-repressed by glucose. This repression by glucose was obvious in the arcA mutant. ArcA is the positively acting transcriptional regulator of the oxygen regulated genes. The molecular mass of the protein product of ubiA was 32kD, found using the over-expression of the ubiA gene.

Base Sequence↗
PubMed1993

[Transition of diagnosis and treatment for impotence].

Statistic study was made on 685 outpatients with erectile dysfunction during 13 years periods from 1979 to 1991 in the Department of Urology, Takamatsu Red Cross Hospital. The age distribution showed the highest frequency in the thirties decade (27.9%). 1. Diagnosis Nocturnal penile tumescence monitoring was the only method to distinguish organic impotence from functional impotence during the first 5 years. From 1984 we have been able to diagnose corporal veno-occlusive insufficiency (CVI) by papaverine test and dynamic infusion cavernosometry and cavernosography. Measurement of penile brachial index and pelvic angiography were performed to diagnose arterial insufficiency (AI). In neurological examination we have measured bulbo-cavernosus reflex latency and nerve conduction velocity of the dorsal penile nerve and performed microvibration measurement and sweat spots test. All diagnostic methods were established in 1987 and we have been able to classify about 80% patients. We classified 305 patients during the last 5 years from 1987 as follows: psychogenic; 31.1%, CVI; 20.0%, AI; 7.9%, neurogenic; 7.9%, others; 14.1%, drop-out and unknown; 19.0%. 2. Treatment In the beginning only counseling and drug therapy were performed. However we lately performed various suitable methods for individuals based on their diagnoses. We performed counseling, drug therapy and intracavernous injection of vasoactive drug therapy for recovery of spontaneous erection (vascular training) for psychogenic IMP. The efficacy rate of counseling was low (30.4%) but that of drug therapy was 41.6%, and that of vascular training, 64.2%. For CVI without other factors we performed venous surgeries. Only about 25% of them perform sexual intercourse with or without self injection of vasoactive drug (self injection).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

[The relaxation of human corpus cavernosum caused by nitric oxide].

Non-adrenergic non-cholinergic nerves (NANC) are thought to be important in the relaxation of corpus cavernosum for erectile function. On the other hand, it has been shown that nitric oxide (NO) is synthesized from L-arginine and released by the endothelium of blood vessels and accounts for the activity of endothelium-derived relaxing factor (EDRF). We studied whether electrical field stimulation (EFS) of isolated strips of human corpus cavernosum released NO and whether it could act as a NANC neurotransmitter. Human penile tissue specimens were mounted in an organ bath and the isometric tension recorded. EFS was applied to precontracted strips between two parallel platinum electrodes. Relaxation induced by EFS was not influenced by guanethidine or atropine, but was markedly inhibited by NG-nitro-L-arginine which is an analog of L-arginine that inhibits the conversion of L-arginine to NO, and hemoglobin which is an agent that inhibits the biological actions of NO. Methylene blue which is an inhibitor of cytosolic guanylate cyclase also reduced the relaxation of EFS, but not completely. The inhibitory effect of NG-nitro-L-arginine was reversed by addition of excess L-arginine. Exogenous NO relaxed human corpus cavernosum. The relaxation was only a transient response and concentration-dependent. The profile of responses is similar to that evoked by EFS. Our data clearly demonstrate the release of NO during EFS and the function of NO as a NANC neurotransmitter. Human penile erection may be mediated by NO generated in response to NANC neurotransmission.

Adult↗
PubMed1993

[A case of penile revascularization by Hauri's method for arteriogenic impotence].

In a 35 year old arteriogenic impotent patient without a history of hypertension, arteriosclerotic disease, or diabetes mellitus, the corpus cavernosum of the penis was revascularized using Hauri's method. Before surgery, erection after the intra-cavernous injection of 20 micrograms of prostaglandin E1 was very weak. In a color ultrasonography the peak systolic velocity of the cavernous arteries was recorded as being only 18 cm/sec. Furthermore, no artery except the right dorsal artery was evident even with a digital subtraction angiography. Accordingly he was diagnosed as having arteriogenic impotence, and we carried out the corpus cavernosum revascularization using Hauri's method under microscopic magnification. The dorsal artery and the deep dorsal vein were anastomosed side-to-side, and the hypogastric artery and dorsal artery were anastomosed end-to-side. After the revascularization surgery, the peak systolic velocity of cavernous arteries returned to normal (53 cm/sec), and the penis showed complete erection after an intracavernous injection of 20 micrograms of prostaglandin E1. Before surgery this patient had no experienced sexual intercourse, but he could achieve full sexual intercourse 2 weeks after the surgery. His erectile ability has been maintained for 4 months since the surgery. This is the 1st case of arteriogenic impotence treated using Hauri's method in Japan.

Adult↗