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Biomedical subjects

N Yoshimura

Publications and source records attributed to N Yoshimura.

At least 289 records · Page 16Linked to original sources
PubMed1996

Differential respiratory activity of four abdominal muscles in humans.

Together the abdominal muscles contribute significantly to ventilation under some conditions, but there is little information regarding individual recruitment and timing of activation of the four abdominal muscles in humans. Fine-wire electrodes were inserted under direct vision guided by high-resolution ultra-sound into the rectus abdominis (Rectus), external oblique (Extern), internal oblique (Intern), and transversus abdominis (Transv) in nine awake healthy subjects. Airflow, end-tidal CO2, and moving-average EMG signals were recorded during 1) supine resting and CO2-stimulated ventilation and 2) resting ventilation in the standing position. During resting supine breathing, Transv showed significant phasic EMG activity during expiration. As posture changed from supine to standing, phasic activity during resting ventilation was greatest in Transv, with lesser activity in Intern and Extern, while Rectus remained inactive. As CO2 began to increase, Transv was activated first, followed by Intern, the Extern, and finally Rectus. With moderate CO2 stimulation, Transv and Intern were more active than was Extern and Rectus remained least active. EMG activities in the expiratory muscles after cessation of expiratory flow (postexpiratory expiratory activity) and in expiratory muscle activity preceding expiratory flow were observed consistently during supine stimulated ventilation and standing resting ventilation. These activities before and after expiratory airflow were prominent with stimulated ventilation during a substantial portion of inspiration, suggesting dual control of inspiratory pump action by both inspiratory and expiratory muscles, which provide acceleration and braking actions, respectively. These results suggest that in awake humans 1) during resting ventilation, expiration is an active process; 2) abdominal muscles are activated differentially; 3) Transv is the most active, Intern and Extern are intermediate, and Rectus is the least active expiratory muscle; and 4) during stimulated ventilation, inspiratory and expiratory muscles contribute dually to inspiratory pump action.

Abdominal Muscles↗
PubMed1996

Characterization of voltage-sensitive Na+ and K+ currents recorded from acutely dissociated pelvic ganglion neurons of the adult rat.

1. Electrophysiological properties of acutely dissociated neurons from the major pelvic ganglion (MPG) of the adult male rat were studied with whole cell patch-clamp recording techniques. The MPG neurons innervating the urinary bladder were labeled by retrograde axonal tracing methods with the use of a fluorescent dye, Fast Blue (FB) injected into the bladder wall and identified with a fluorescent microscope. 2. Passive and active membrane properties such as resting membrane potential, input resistance, duration of action potentials, thresholds for spike activation, or duration of afterhyperpolarization in unidentified MPG neurons were comparable with those of FB-labeled neurons innervating the urinary bladder. The action potential in both unidentified and bladder efferent MPG neurons was reversibly abolished by tetrodotoxin (TTX, 1 microM). The afterhyperpolarization of the TTX-sensitive action potential in both groups was reduced by application of Cd2+ (0.1 mM) and further suppressed by tetraethylammonium (TEA, 10 mM). Extracellularly applied TEA increased the duration of the action potential, and 4-aminopyridine (4-AP, 1 or 2 mM) also reduced the spike afterhyperpolarization and increased the spike duration. The duration of the action potential was decreased and the rate of spike repolarization was increased by approximately 2.5-fold with negative shift of membrane potential from -40 to -80 mV. 3. The isolated Na+ current was reversibly blocked by 1 microM TTX and had a mean peak amplitude of 127.3 pA/pF when activated from a holding potential of -70 mV in the external solution containing 100 mM Na+. The Na+ conductance reached half-maximal activation at a membrane potential of -21.5 mV with a slope factor of 4.9 mV. The steady-state inactivation of Na+ conductance occurred at membrane potentials more depolarized than -90 mV, and the half-maximal inactivation was obtained at -57.5 mV with a slope factor of 8.8 mV. 4. The fast-transient A-type K+ current (IA) was activated at membrane potentials more depolarized than -60 mV from a holding membrane potential of -100 mV, reached a peak amplitude within 10 ms after the onset of depolarizing voltage steps, and decayed within 20-30 ms at membrane potential depolarizations to +20 to +30 mV. The IA current activated by a voltage step to +20 mV from a holding potential of -100 mV averaged 102.1 pA/pF. The half-maximal activation of the IA conductance was obtained at a membrane potential of -21.2 mV with a slope factor of 9.9 mV. In steady-state inactivation of IA current, the half-maximal inactivation occurred at -76.5 mV and the slope factor was 8.0 mV. 5. The delayed K+ current was reduced by 25-35% by bath application of Cd2+ or the elimination of extracellular Ca2+ ions. The bath application of 4-AP (2 mM) suppressed the IA current by 75% and the delayed K+ current by 60%. Extracellularly applied TEA (10 mM) suppressed the delayed K+ current by 90%, but suppressed the IA current by only 16%. 6. These results indicate that bladder neurons and unidentified neurons in the MPG have similar properties including a TTX-sensitive Na+ current and three distinct types of voltage-sensitive K+ currents-IA current, Ca(2+)-activating K+ current, and delayed rectifier K+ current-that contribute to the repolarization phase of the action potential. These electrical properties of the MPG neurons resemble those of sympathetic neurons in the superior cervical and inferior mesenteric ganglia.

Action Potentials↗
PubMed1996

Increased cytokine gene expression in rat retina following transient ischemia.

Tumor necrosis factor (TNF) gene expression in rat retina following transient ischemia was studied by semiquantitative reverse transcription-polymerase chain reaction (RT-PCR). Gene expression for other cytokines was also studied by RT-PCR. Although very little expression for TNF gene was detected in normal retina, it was markedly increased 0.5-48 h after reperfusion, with peak expression at 12 h (20-fold of control). Gene expression for interleukin-6, interferon-gamma, and transforming growth factor-beta 1 was also increased. The results provide evidence that retinal ischemia can up-regulate cytokine gene expression in the retina.

Animals↗
PubMed1996

Immunosuppression in organ transplantation.

The immunological barrier remains the major obstacle to the widespread use of transplantation as a replacement therapy for terminal organ failure. Since the first successful renal transplant, performed by Hume et al. (1952), there has been an elusive search for agents that can render the immune mechanism unresponsive to the specific alloantigen stimulus of the engrafted organ, while sparing non-specific host resistance. Immunosuppressive therapies in organ transplantation can be divided into the following four main classes: chemical (pharmaceutical), biological (immunological), physical (radiological) and surgical. Of these, chemical agents (drugs) have continued to play a principal role. The discovery of new immunosuppressive drugs such as corticosteroids, ciclosporin, azathioprine and FK506 have been epoch-making discoveries at each stage in the history of clinical organ transplantation. The recent immunosuppressants were designed to focus their action selectively on T and/or B cells by inhibiting cytokine synthesis (ciclosporin, FK506), cytokine action (rapamycin), or cell differentiation (15-deoxyspergualin) pathways, rather than to act on immune systems in a non-selective fashion. At the present time, however, there is no single panacea. To achieve the maximum preventive and therapeutic effects with the minimum toxicity, two or more immunosuppressive drugs are used appropriately in combination, taking the mechanisms of action of each into consideration.

Adrenal Cortex Hormones↗
PubMed1996

[A population survey on bone mineral density in a fishing village in Wakayama prefecture. (Part 1) Distribution of bone mineral density by sex and age based on a representative sample of the community].

To establish reference values for bone mineral density (BMD), a population survey was carried out in a fishing community in Wakayama Prefecture. The BMD measurements of the lumbar spine (L2-L4) and proximal femur (femoral neck, trochanter and Ward's triangle area) were performed by sex and age, using dual-energy X-ray absorptiometry. Four hundred subjects, aged 40 to 79 years, were recruited randomly to give 50 persons in each of eight age-sex strata from a list of 2,261 residents (1,028 men and 1,233 women) living in a fishing village. The validity of sampling methods was assessed using a questionnaire about lifestyle factors, which was used for all residents aged from 40 to 79 years in the baseline survey. There were no significant differences between the subjects for BMD measurements and all the residents of the community in the frequencies of past history of diseases, healthy habits, food intakes, and rates of smoking, alcohol drinking, coffee and green tea consumption. These findings suggested that the present study population could be considered representative of samples obtained from the entire population in the fishing community. The results of BMD measurements in these subjects, who were selected at random, showed that except for a slightly high BMD of the lumbar spine in men in their 60's, the mean BMD of the lumbar spine and the three proximal segments of the femur decreased with increasing age in both sexes.

Adult↗
PubMed1996

[A population survey on bone mineral density in a fishing village in Wakayama Prefecture (Part 2); The analysis of the risk factors affecting the bone mineral density].

The purpose of this study was to detect factors affecting lumbar bone mineral density (BMD) of general inhabitants in a rural community. A cohort consisting of 2261 inhabitants aged 40-79 years was set up based on the resident registration in Taiji town, Wakayama Prefecture in 1992. Fifty men and 50 women in each of four age strata (40-49, 50-59, 60-69, 70-79), totaling 400 inhabitants, were selected randomly. After completion of a questionnaire by an interviewer, items about physical characteristics such as height, body weight, wrist length and grip power were measured. Examination of BMD of the lumbar spine and proximal femur by dual energy X-ray absorptiometry was performed. Correlation coefficients between BMDs and values of physical characteristics were determined. Lumbar BMD was examined to determine whether the following factors were positive or negative: past history, alcohol consumption, smoking habit, dietary habit, exercise, and in addition, pregnancy times and menstrual status for women. Among the values of physical characteristics, body weight was the most closely correlated with lumbar BMD. The items that showed significantly high values as factors affecting lumbar BMD were a past history of diabetes mellitus (men and women in their 70s), and exercise (men in their 50s and women in their 40s). Regarding pregnancy times and menstruation, BMD in women with a history of childbirth was significantly higher than that in those without the history among the women in their 70s. Although the BMD in the women with lactation was significantly lower than that in those without it among the women in their 40s, there was no difference in BMD between the women with and without the history who were 50 years old or over. The effect of menstrual status was investigated according to years after menopause in the women in their 50s. BMD was significantly lower in the women with ar least six years after menopause than in those within five years.

Adolescent↗
PubMed1996

Profile of chest injuries arising from the 1995 southern Hyogo Prefecture earthquake.

STUDY OBJECTIVE: To better understand the types of chest injuries that are likely to occur following a major earthquake in the urban environment, we analyzed the pattern of chest injuries arising from the earthquake that struck the southern part of Hyogo Prefecture in Japan at 5:46 AM on January 17, 1995 and registered 7.2 on the Richter scale. DESIGN AND SETTING: The medical records of 487 patients with injuries who were referred to Kobe University Hospital from January 17 to January 23 were reviewed. RESULTS: Of the 487 patients, 63 (12.9%) were found to have chest injuries. Of these 63, eight patients with severe chest compression were dead on arrival at the hospital. Eight patients were admitted to our hospital, two of whom developed crush syndrome. The remaining 47 (74.6%) patients had light to moderate injuries and were treated in the emergency department on an outpatient basis. CONCLUSIONS: Minor trauma was the most common type of chest injury. However, there were severely injured patients who were trapped in collapsed buildings.

Adolescent↗
PubMed1996

Recurrent histiocytic necrotizing lymphadenitis (Kikuchi's disease) in an human T lymphotropic virus type I carrier.

We describe a case of recurrent histiocytic necrotizing lymphadenitis (HNL) with aseptic meningitis. The patient was a 46-year-old male and a carrier of human T lymphotropic virus type I (HTLV-I). The patient had a past medical history of at least three relapses of HNL. In addition, his sister, who was also an HTLV-I carrier, had recurrent clinical episodes consistent with those of HNL, suggesting familial HNL occurrence. This observation suggests the possibility that HTLV-I infection is relevant to the pathogenesis of HNL.

Antibodies, Viral↗
PubMed1996

Endothelin protein expression in tear glands of the rabbit.

PURPOSE: Endothelin-1 (ET-1) has been found to accelerate rabbit corneal epithelial wound healing in vivo and proliferation of rabbit and bovine epithelial cells in vitro. We have now determined that endothelin-like immunoreactivity (ET-LI) is present in the tear fluid of New Zealand white rabbits, and we have addressed the question of whether it is produced by the tear glands (lacrimal gland and Harderian gland). METHODS: Tears were obtained with capillary pipettes and lacrimal gland fluid was collected by cannulation. ET-LI was determined with a sandwich-enzyme immunoassay. The reverse transcriptase-polymerase chain reaction (RT-PCR) was employed to determine if there are gene transcripts for prepro ET-1 in tear glands. ET-LI in the tear glands was evaluated using immunohistochemistry. RESULTS: The tears contained 13.85 +/- 3.94 pg/ml (mean +/- SEM, n = 6) ET-LI and the lacrimal gland fluid had 24.90 +/- 6.00 pg/ml (n = 6). The plasma contained 0.89 +/- 0.20 pg/ml (n = 6). Gene transcripts were identified for prepro ET-1 in the lacrimal and Harderian glands. Specific staining for ET-LI was found in the epithelial cells of the ducts of the lacrimal gland and the acinar cells of the Harderian gland. CONCLUSIONS: The higher concentrations of ET-LI in the tears and the lacrimal gland fluid than in plasma along with prepro ET-1 gene transcripts in the tear glands suggest that they secrete ET-1.

Animals↗
PubMed1996

Role of nitric oxide synthase isozymes in endotoxin-induced uveitis.

PURPOSE: The authors previously reported that in vitro treatment with N(G)-nitro L-arginine (L-NNA), an inhibitor of nitric oxide synthase (NOS), reduces aqueous humor (AH) protein and cellular infiltration in endotoxin-induced uveitis in the rat eye. The objective of the current study was to determine the role(s) of respective major forms (constitutive and inducible) of NOS by comparing the effects of relatively selective inhibitors of these NOS isozymes. METHODS: N(G)-nitro L-arginine (L-NNA), a relatively selective inhibitor for constitutive NOS (c-NOS), and N-iminoethyl L-ornithine (L-NIO), a more selective inhibitor for inducible NOS (i-NOS), were administered in vivo. Male Lewis rats were footpad injected with bacterial lipopolysaccharide (LPS, 200 microgram) and were injected intraperitoneally at 0 hours, 6 hours, or both, after LPS injection with 10 mg of NIO, NNA, or saline as a control. Nitric oxide synthase activity in the ocular tissue and AH protein and cell content were determined at various times after treatment with LPS. RESULTS: After in vivo treatment, L-NIO was found to be a more potent inhibitor than L-NNA for ocular i-NOS (87% versus 43% inhibition), and L-NNA was more potent than L-NIO for ocular c-NOS (81% versus 39%). Two injections of L-NNA, one at time 0 and one 6 hours after LPS injection, inhibited the AH protein increase by 71%, but L-NIO did so by only 30%. L-NNA inhibited cellular infiltration by 86%, whereas L-NIO had no significant effect on cellular infiltration. A significant inhibition of cellular infiltration and AH protein increase also was observed with a single injection of 10 mg of L-NNA but not of L-NIO when the inhibitors were given simultaneously with LPS. Thus, reduction of uveitis symptoms correlates with the inhibition of c-NOS. CONCLUSIONS: The constitutive form of NOS in ocular tissue, presumably in vascular endothelial cells, appears to play a critical role at the onset of the development of endotoxin-induced uveitis.

Animals↗
PubMed1996

[Diagnosis of lung cancer using functional image of 201Tl SPECT with parameter of 201Tl retention--evaluation of its applicability to post irradiated lung cancer].

Thallium-201 (201Tl) SPECT is a useful method for detecting lung cancer. Moreover, the 201Tl Retention Index (R.I.) reported by Tonami et al is now available for differentiating pulmonary lung cancer from benign lesions. The diagnosis of recurrent tumors is, however, difficult to establish as they are often shaded by radiation pneumonitis or fibrosis. Therefore, we employed functional images (F.I.) obtained using as parameter a modified version of the R.I. First we indicated the statistical value of untreated solitary lung tumor as follows: sensitivity 84.6%, specificity 80.0%, and accuracy 83.3%. In our assessment, the lesions with tumor size over 2.0 cm and R.I. by Tonami et al over 12.7 were detected as positive images. Secondly in assessment of 22 cases (23 lesions) of post irradiated lung cancer, the results obtained were: sensitivity 80.0%, specificity 92.3%, and accuracy 87.0%. 201Tl SPECT functional images seem to be useful for the diagnosis of recurrent lung cancer by shaded radiation pneumonitis and fibrosis.

Adenocarcinoma↗
PubMed1996

[Usefullness of transesophageal echocardiography in early detection of coronary spasm].

Intraoperative transesophageal echocardiography (TEE) was performed on a 62-year-old man who underwent abdominal aortic replacement for abdominal aortic aneurysm under general anesthesia combined with epidural anesthesia. Coronary artery spasm occurred after unexpected massive hemorrhage, and TEE showed hypokinesis in the posterior-inferior left ventricular wall. The changes in TEE preceded the ST elevation in the ECG. Bolus infusion of isosorbide dinitrate and continuous infusion of nitroglycerin alleviated these changes. TEE enabled us to detect and evaluate coronary spasm before the appearance of ST changes in ECG.

Anesthesia, Epidural↗
PubMed1996

[Preanesthetic evaluation of cardiovascular reserve in a patient with dilated cardiomyopathy].

We described an anesthetic management of a patient with abdominal aortic aneurysm associated with dilated cardiomyopathy (DCM) focusing on preanesthetic evaluation of cardiovascular reserve and on intraoperative continuous circulatory monitoring with transesophageal echocardiography (TEE) and continuous cardiac output measurement (CCO). Based on echocardiographic and hemodynamic measurements after a 50 m-walk load, we predicted the allowable range of alteration of preload (LV diastolic dimension; Dd), myocardial performance (arterial blood pressure and ejection fraction) and of heart rate. During anesthesia and operation, we continuously monitored Dd, arterial blood pressure, heart rate and cardiac output, and maintained these variables within the allowable range. The changes in preload after clamping or unclamping of the aorta was promptly reflected by Dd as compared to pulmonary capillary wadge pressure. The CCO was also usuful in detecting abrupt changes in myocardial performance. In conclusion, we suggest preanesthetic stress test to be performed to evaluate cardiovascular reserve and to predict the allowable range of alteration of hemodynamic variables. Continuous monitoring of preload (Dd) by TEE and of myocardial performance by CCO is useful to detect early changes in these variables.

Anesthesia, General↗
PubMed1996

[Surgical-treatment for active infective endocarditis].

The results of surgical treatment of active native infective endocarditis in 24 patients were analyzed. Fifteen of 24 (63%) patients were successfully cured by operation. Three of the 8 patients with severe cardiac failure who underwent emergency operation died of low cardiac output syndrome and bleeding early postoperatively. One of the 6 patients with late death had preoperative cerebral embolism and died of multiple organ failure. Five of them had annular infection. Among 6 patients with annular infection, 3 patients who had Staphylococcus epidermidis and Gram negative bacterium as a causative microorganism had a short duration within 4 weeks from the onset to operation. Two died suddenly in the long-term period after surgery because of prosthetic valve detachment. The second operation were required for other 4 patients because of prosthetic valve endocarditis or perivalvular leakage. Three of them were lost from low cardiac output syndrome. These findings suggested that delayed surgical intervention may be a major causative factor resulting in high surgical mortality. For patients with active native infective endocarditis, an early aggressive operation should be considered prior to congestive heart failure and the destruction of the annulus.

Adult↗
PubMed1996

[Myocardial ischemia induced by air bubbles].

Intraoperative transesophagial echocardiography (TEE) was performed in a 27-year-old man who underwent direct suture for atrial septal defect (ASD) under general anesthesia. Myocardial ischemia occurred about five minutes after weaning from cardiopulmonary bypass, and at that time TEE showed that anteroseptal wall, lateral septal wall and lateral wall are severely hypokinetic and another wall is diffusely hypokinetic in the left ventricle after detecting air bubbles in the left ventricle by TEE. The changes in TEE preceded the ST elevation in the ECG. Bolus infusion of isosorbide dinitrate and continuous infusion of nitroglycerin showed no effects on these changes. Ten minutes after the onset of myocardial ischemia, these changes were alleviated. TEE enabled us to detect air bubbles and evaluates myocardial ischemia before the appearance of ST changes in ECG.

Adult↗
PubMed1996

[A population based study on factors related to bone mineral density in Wakayama Prefecture].

For evaluation of the community health program, 1543 inhabitants aged 40-79 years were recruited as cohort members in Miyama Village, Wakayama Prefecture. In this cohort, bone mineral density (BMD) of 400 subjects, 50 males and 50 females each randomly selected from each of four age strata, was measured at the lumbar spine and femur neck by dual energy X-ray absorptiometry. Information on exposure to possible risk factors was obtained from a self-administered questionnaire. The results were as follows; BMD at the lumbar spine and femur neck in women aged 70-79 who maintained an exercise habit (> or = one hour/week) was significantly higher than women with no exercise habit. The BMD at the femur neck in men aged 60-79 with alcohol drinking habit was significantly higher than those with no drinking habit. Significant correlation was not seen between milk intake or smoking and the BMD. BMD at the femur neck in women aged 60-69 with multiple child births (> or = 4) were significantly higher than those with fewer child births. The BMD in women aged 50-59 with earlier onset of menarche was higher than those with late menarche. Significant reduction in BMD of postmenopausal women was observed compared to premenopausal women analyzed after matching for age. The result of analysis of quantification method of the first type showed that age and menopause had a marked effect on BMD. Concerning lifestyles as other factors, a positive correlation was observed between BMD and drinking for men and exercise for women. These factors appear to be useful indicators of risk for osteoporosis.

Adult↗