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Biomedical subjects

M Miyamoto

Publications and source records attributed to M Miyamoto.

At least 163 records · Page 9Linked to original sources

Time course of morphine withdrawal and preproenkephalin gene expression in the periaqueductal gray of rats.

We have previously reported the increase of preproenkephalin (PPE) mRNA in the caudal periaqueductal gray (PAG) of rats during morphine withdrawal. In this study, it was further evidenced that PPE mRNA in the caudal PAG was not increased by various kinds of stressor, suggesting that the increase in PPE mRNA in the caudal PAG is specific to morphine withdrawal. In order to investigate the physiological significance of the increase of PPE mRNA in the caudal PAG, we compared the time course of the increase of PPE mRNA in the caudal PAG with that of naloxone-precipitated or spontaneous morphine withdrawal signs. The increase of plasma corticosterone (PCS: 52 and 52 microg/100 ml; control group, 18 and 15 microg/100 ml) and body weight loss (-6 and -9%; control group, 0 and -1%) were observed but PPE mRNA increase was not detected 1 and 2 h after naloxone in morphine treated rats. PPE mRNA increased by 37 to 56%, while PCS elevation and body weight loss gradually diminished 4 h to 2 days after naloxone. A total of 12 h after spontaneous withdrawal, PCS was prominently increased (51 microg/100 ml; control group, 12 microg/100 ml), but body weight and PPE mRNA were not affected. One day after spontaneous withdrawal, PCS elevation (38 microg/100 ml; control group, 8 microg/100 ml) and body weight loss (-5%; control group, +3%) were observed and PPE mRNA also increased by 42%. Two to 3 days after the final morphine injection, PCS recovered to control level and body weight loss gradually disappeared, while PPE mRNA was still increased by 74 to 46%. These results suggest that PPE gene expression in the caudal PAG is stimulated in the recuperative phase of these morphine withdrawal signs.

Animals↗

Prenylflavonoids: a new class of non-steroidal phytoestrogen (Part 2). Estrogenic effects of 8-isopentenylnaringenin on bone metabolism.

In order to examine whether 8-isopentenylnaringenin (1), which has been proven to possess estrogen agonist activity in in vitro tests, also produces in vivo estrogenic properties, the effects of 1 on uterus and on bone metabolism were determined in ovariectomized rats. Rats were ovariectomized and treated with 1 at 30 mg/kg/day subcutaneously for two weeks or 17 beta-estradiol at 0.01 mg/kg/day subcutaneously for two weeks. Ovariectomy resulted in an increase in urinary excretion of bone resorption markers (hydroxyproline, pyridinoline and deoxypyridinoline) and a decrease in bone mineral density of the proximal tibia as well as reduced uterine weight. Treatment with 1 or 17 beta-estradiol completely suppressed these ovariectomy-induced bone and uterine changes in a qualitatively similar manner. These results demonstrate that 1 acts as an estrogen agonist in the uterus as well as in bone in vivo.

Amino Acids↗

Late postoperative respiratory function in adults after surgical correction of atrial septal defects. Analysis of respiratory dysfunction patterns.

Respiratory function after repair of atrial septal defect (ASD) was analysed in 44 adults (> 40 years), 21 of whom had preoperative respiratory dysfunction, 14 of restrictive type, defined as % vital capacity (% VC) less than 80% of predicted value, 3 with an obstructive pattern, defined as % forced expiratory volume/1 s (% FEV1) less than 70% of predicted value, and 4 patients with a mixed pattern. Increased % VC was found postoperatively in all 14 patients with restrictive respiratory dysfunction, with normal values in 8 out of the 14. Although the three patients with obstructive, and the four with mixed-pattern respiratory dysfunction improved preoperatively in % VC or % FEV1, or both, none had normalized values. We conclude that preoperative restrictive respiratory dysfunction in ASD patients frequently normalizes postoperatively, but not dysfunction of obstructive or mixed restrictive-obstructive type.

Adult↗

LAP-1 cold preservation solution for isolation of high-quality human pancreatic islets.

The most critical factors that affect the outcome of clinical pancreatic islet transplantation are the number and quality of donor islets available for transplantation. Toward this goal, we attempted to obtain islets that are both of better quality and higher number than are obtainable by the islet-isolation process that is now widely used. We paid special attention to two critical components of the isolation procedure: minimizing the exposure of pancreatic tissue and freed islets to warm enzyme solution, and development of a preservation solution suitable for islets during cold storage of digested pancreatic tissue-free islets. For this purpose, we developed both a two-step procedure for pancreas digestion and a new cold preservation solution, the LAP-1 solution (Los Angeles preservation solution 1). In this study, we evaluated the effect of four preservation solutions by storing digested pancreatic tissues on ice for 90 min. After the cold storage, islets were purified on three layers of Euro-Ficoll solutions in a 50-ml tube, and the islet yield, viability, and function were determined. These experiments were performed by using samples from 10 consecutive islet isolations. Results with LAP-1, original University of Wisconsin solution (oUW), and modified UW solution (mUW;UW without hydroxyethyl starch) were compared with those obtained with Hank's balanced salt solution (HBSS). The islet yield was significantly higher in the LAP-1 and mUW groups as compared with the HBSS group (p < 0.01). The islet purity was significantly better in the LAP-1, oUW, and mUW groups than the HBSS (p < 0.001). The islet viability was lowest in the HBSS group immediately after purification (vs. LAP-1, oUW, and mUW, p < 0.05) and further decreased during culture (p < 0.01). Both the number and viability of cultured islets were the highest with LAP-1 solution but without statistical significance between mUW and oUW. Electron microscopic examination showed only slight damage to cell membranes immediately after purification of islets stored in LAP-1 solution and their complete recovery within 1-2 days of culture. These islets also exhibited normal insulin responses to high glucose by static incubation and perifusion assays.

Adolescent↗

Evaluation of sleep using ambulatory skin potential recording: differences between morning and evening type.

In order to validate the evaluation of sleep using cassette type ambulatory skin potential measurement system (C-SPA), sleep duration variables extracted from 24 h recordings were compared between two groups (16 of the intermediate type and 16 of the evening type) with different sleep-wake habits rated by Morningness and Eveningness Questionnaires (MEQ). Compared with the intermediate type, the evening type subjects go to bed and get up later, have difficulty in falling asleep and more frequently awaken during sleep. Thus, the sleep variables by C-SPA provide valuable information about duration of sleep and differentiate the sleep-wake habits.

Activity Cycles↗

A case of Arnold-Chiari Type I malformation presenting with dysrhythmic breathing during sleep.

A 43-year-old woman presented with dull headache, left tinnitus and dizziness. Neurological examination revealed down-beat gaze nystagmus, left tinnitus, positive Romberg sign, poor standing on the left foot, poor tandem gait, left spastic gait and positive pathological reflexes in the bilateral upper and lower extremities. Plain X-ray of the skull and cervical vertebrae demonstrated basilar impression and atlantoaxial fusion. Magnetic resonance imaging of the brain and cervical spine showed cerebellar tonsil descent and syringomyelia located in the left side of the spine at the II-III vertebral level which communicated with the fourth ventricle. The patient was diagnosed as having cervical syringomyelia. Arnold-Chiari type I malformation and basilar impression. Preoperative polysomnography showed dysrhythmic breathing and bradypnea during sleep. Abnormal breathing improved after suboccipital decompression craniotomy and upper cervical laminectomy. It was suggested that dysrhythmic breathing was caused by a disorder of the medullary respiratory center. Herniation of the cerebellar tonsil and syringomyelia might have compressed the medulla.

Adult↗

Effects of hypoproteinemia-induced myocardial edema on left ventricular function.

In previous studies, we observed left ventricular (LV) systolic and diastolic dysfunction in association with interstitial myocardial edema (IME) induced by either coronary venous hypertension (CVH) or lymphatic obstruction. In the present study, we examined the effects of myocardial edema induced by acute hypoproteinemia (HP) on LV systolic and diastolic function. We also combined the methods of HP and CVH (HP-CVH) to determine their combined effects on LV function and myocardial water content (MWC). We used a cell-saving device to lower plasma protein concentration in HP and HP-CVH groups. CVH was induced by inflating the balloon in the coronary sinus. Six control dogs were treated to sham HP. Conductance and micromanometer catheters were used to assess LV function. Contractility, as measured by preload recruitable stroke work, did not change in control or HP groups but declined significantly (14.5%) in the HP-CVH group. The time constant of isovolumic LV pressure decline (tau) increased significantly from baseline by 3 h in the HP (24.8%) and HP-CVH (27.1%) groups. The end-diastolic pressure-volume relationship (stiffness) also increased significantly from baseline by 3 h in the HP (78.6%) and HP-CVH (42.6%) groups. Total plasma protein concentration decreased from 5.2 +/- 0.2 g/dl at baseline to 2.5 +/- 0.0 g/dl by 3 h in the HP and HP-CVH groups. MWC of the HP (79.8 +/- 0.25%) and HP-CVH groups (79.8 +/- 0.2%) were significantly greater than that of the control group (77.8 +/- 0.3%) but not different from one another. In conclusion, hypoproteinemia-induced myocardial edema was associated with diastolic LV dysfunction but not systolic dysfunction. The edema caused by hypoproteinemia was more than twice that produced by our previous models, yet it was not associated with systolic dysfunction. CVH had a negative inotropic effect and no significant influence on MWC. IME may not have the inverse causal relationship with LV contractility that has been previously postulated but appears to have a direct causal association with diastolic stiffness as has been previously demonstrated.

Acid-Base Equilibrium↗

Enhancing effect of N-acetyl-l-cysteine or 2-mercaptoethanol on the in vitro permeation of 5-fluorouracil or tolnaftate through the human nail plate.

The enhancing effects of various vehicles on the in vitro permeation of a hydrophilic model drug, 5-fluorouracil (5-FU), or a lipophilic model drug, tolnaftate (TN), through human nail plates were investigated using a modified side-by-side diffusion cell. Tip pieces from the 5th finger-nail, clipped from healthy volunteers, were used in this permeation study. The swelling and softening properties of the nail pieces were also measured in each vehicle. The weights and stresses of the nail pieces were dramatically changed after immersion in aqueous solvents containing N-acetyl-L-cysteine (AC) or 2-mercaptoethanol (ME). However, no significant change in the physicochemical properties of the nail pieces was found in the lipophilic vehicles. Thus, the water content in the nail plates absorbed from vehicles may relate to their physicochemical properties. Although keratin-softening agents and new skin permeation enhancers did not significantly promote 5-FU permeation compared with water alone, the flux from solvent systems containing AC or ME was substantially higher. In addition, TN permeation from solvents containing AC or ME could be measured, whereas that from other solvents was undetectable. When the AC concentration was increased, the 5-FU permeation and the nail weight increased and the stress of each nail piece decreased. It is concluded from these experimental results that AC and ME may be useful as enhancers for increasing drug permeation through the human nail plate.

Absorption↗

Effects of peptidase inhibitors, [D-Ala2, Met5]-enkephalinamide and antiserum to methionine-enkephalin microinjected into the caudal periaqueductal gray on morphine withdrawal in rats.

We examined the involvement of enkephalins in the caudal periaqueductal gray (cPAG) in morphine withdrawal in rats. Rats were treated with increasing doses of morphine (20-30 mg/kg/day, s.c., for 5 days) to develop morphine dependence. Morphine withdrawal was induced by naloxone (5 mg/kg, s.c.) 24 hr after the final morphine injection. The level of preproenkephalin (PPE) mRNA in the cPAG was estimated by quantitative in situ hybridization. PPE mRNA in the cPAG was increased 4-24 hr after naloxone in morphine-treated rats. A mixture of peptidase inhibitors (0.5 microl of a solution of amastatin, captopril and phosphoramidon, 3 x 10(-3) M each) microinjected into the cPAG suppressed morphine withdrawal (a decrease in the number of jumping, chin rubbing, paw rubbing and teeth chattering). Antiserum to methionine-enkephalin (1:10 dilution) microinjected into the cPAG did not significantly aggravate morphine withdrawal with or without the mixture of peptidase inhibitors. However, [D-Ala2, Met5]-enkephalinamide (20 nmol), an enkephalin analog, injected into the cPAG decreased the number of jumping without any influence on the other withdrawal signs. These results suggest that the increase in enkephalins in the cPAG may participate in the alleviation of morphine withdrawal (jumping behavior).

Animals↗

Combination of low back pain and previous low back pain and shoulder stiffness in construction employees.

A postal questionnaire for the prevalence of low back pain was studied with relevance to stiffness of that shoulder and a history of low back disorders in construction employees. The percentage of clerical employees with low back pain was 31.3% and of field workers was 30.3%. Odds ratios representing a relative risk factor for low back pain relating to each age group showed 2.35 in the clerical and 2.10 in the field workers at the age of 30-34 years, and 3.34 and 2.58 at the age of 35-39 years, respectively. In the persons with positive previous low back pain, the prevalence rate of low back pain was 52.6% in the clerical, and 50.2% in the field workers. Odds ratios for low back pain relating to previous low back pain significantly exceeded unity for the clerical employees (OR = 9.53) and the field workers (OR = 10.28), compared to those without a history of previous low back pain. The incidence of stiffness of the shoulder was 48.2% in the clerical and 45.2% in the field workers, and the prevalence rate of low back pain among those with stiffness of the shoulder was 68.5% in the clerical and 65.8% in the field workers. Odds ratio were 3.03 in both groups. Among each age group, the prevalence rate of stiffness of the shoulder with low back pain increased gradually to a maximum in the 45-49 age group of 19%, and then dropped. In those with a history of low back pain and/or stiffness of the shoulder, the prevalence of low back pain showed significantly greater value than other risk factors.

Adult↗

Characteristics of lectin staining patterns assessed by a modified sensitive thermo-method in rat livers with heterologous serum-induced fibrosis.

Lectins are sensitive probes which bind carbohydrate structures specifically. In this study, we modified the lectin staining procedure for sensitive detection of carbohydrate structures in formalin-fixed, paraffin-embedded sections of normal and heterologous serum-induced fibrotic livers. The liver sections were heated in hot distilled water at 100 degrees C for 10 min (thermo-treatment: TT), and then stained with 24 different lectins. In comparison with the results from sections without TT (nonTT), enhanced and/or alternated staining patterns of 19 lectins were demonstrated in sections with TT, and enhanced staining of Vicia villosa agglutinin seen in Kupffer cells was noted. Interestingly, no positive staining was seen with Dolichos biflorus agglutinin, peanut agglutinin or soybean agglutinin (SBA), which recognize O-linked carbohydrate chains, in Kupffer cells of non-TT sections, but strong positive staining was demonstrated in those of TT sections. SBA-positive staining in the cytoplasm of some scattered hepatocytes located in the periportal and perifibrous zones and central zone of pseudolobules was demonstrated only in the fibrotic liver sections with TT. Such findings indicate the heterogeneity of hepatocytes in the liver with fibrosis. Formalin fixation causes masking of lectin binding sites, especially O-linked carbohydrate chains, and TT may recover such masking reactions. TT improved the staining reactions for many lectins in formalin-fixed, paraffin-embedded liver sections, and new staining patterns appear after TT. Modified TT staining procedures may be useful for the diagnosis and prognosis of liver fibrosis.

Animals↗

A novel bone resorption inhibitor, A-75943 isolated from Streptomyces sp. SANK 61296.

A novel bone resorption inhibitor, A-75943, was isolated from Streptomyces sp. SANK 61296. Its structure was determined to be (1"S,2'R,3"S,4S',5"S)-2-[(3",5"- dimethyl-2"-oxocyclohexan-1"-yl)-6'-oxotetrahydropyran-4'-yl ]acetamide by spectral analyses and chemical conversion of cycloheximide. A-75943 inhibited bone resorption in vitro in a concentration-dependent manner with an IC50 of 0.35 microM, and also displayed an inhibitory effect on bone resorption in thyroid and parathyroid-extracted rats.

Animals↗

[Effective nasal CPAP therapy for heavy snoring and paradoxical respiration during sleep in a case of multiple system atrophy].

A 64-year-old man with multiple system atrophy complained of daytime sleepiness, fatigue, and snoring. Neurological examination revealed severe autonomic failure, mild cerebellar ataxia and akinesia. Daytime blood gas analysis showed respiratory acidosis with hypoxia and hypercapnia. MR imaging of the brain showed atrophy of the pons, cerebellum and bilateral frontal lobes. Although paralysis of the vocal cord abduction was not found by laryngoscopy during daytime examination, polysomnography (PSG) showed heavy snoring with paradoxical respiration associated with severe desaturation during sleep as well as reduced slow wave sleep and REM sleep. He was diagnosed as having sleep-related upper airway obstructive breathing disorder probably due to Gerhardt syndrome. Tracheostomy was considered, but we performed nasal CPAP therapy during sleep because this therapy is non-invasive and would not impair his daily life. After nasal CPAP therapy, daytime sleepiness, fatigue, and snoring with desaturation improved, and PSG showed increased slow wave sleep. These results demonstrate that nasal CPAP therapy improves the quality of sleep and should be considered in patients with early stages of multiple system atrophy who exhibit sleep-related breathing disorders.

Humans↗

[Cardiovascular diseases].

Death from heart disease is sometimes observed at night. Life threatening arrhythmias or ischemic heart disease are suspected to be the cause of sudden death during night. Cheyne-Stokes respiration (CSR) is frequently observed in patients with chronic cardiac failure. CSR augments sympathetic nervous activity and reduces the quality of sleep. Sleep apnea or snoring is another stressful condition during sleep. During hyperventilatory phase of sleep apnea, the blood pressure, heart rate, end-systolic ventricular volume and vosomotor tone increases, and the periodic EEG arousal patterns are observed. Sleep apnea is suspected to be one of the risk factors of hypertension. The detection and early treatment of sleep apnea or Cheyne-Stokes respiration are required to reduce the mortality due to cardiac events during sleep.

Cheyne-Stokes Respiration↗

[Surgery for the treatment of infective endocarditis in the active and inactive stages].

Twenty-eight patients (16 M, 12 F, age 11 approximately 72 yr, mean 52.8 yr) underwent surgery for infective endocarditis. Of the 27 patients, 16 were in the active stage and 11 were in the inactive stage. In patients in the active stage, aortic valve replacement (AVR) was performed in 5, mitral valve replacement (MVR) in 7, AVR + MVR in 1, AVR + MVR + tricuspid valve plasty (TVP) in 1 and other procedures in 2. In patients in the inactive stage, AVR was performed in 3, MVR in 4, AVR + MVR in 2, and other procedures in 2. Causative organisms were detected in 56.3% of the patients in the active stage and 54.5% in the inactive stage. Also in patients in the active stage, infection was not prolonged. No deaths occurred among patients in the inactive stage but five patients (31%) died postoperatively; 4 of the five also died, for had severe heart failure before surgery, three died of multiple organ failure and one died of subarachnoid hemorrhage due to infective aneurysm. We recommend surgery for the treatment of infective endocarditis even in the active stage before emergence of heart failure.

Adolescent↗

[Histopathological findings and clinical effects for acute rejections].

We reviewed 115 cases of acute rejection following renal transplantation. All cases were diagnosed after graft biopsy, and showed histopathological evidence of acute rejection. They were treated with administration of OKT3, 15-deoxyspergualin (DSG), anti-lymphocyte globulin (ALG) or methylprednisolone (MP). All rejections were histopathologically classified according to the Banff working classification. The clinical effects of each drug were evaluated both at 1 month and 1 year following the therapy for rejection, by measurement of serum creatinine level. The effective rate both at 1 month and 1 year was related with the Banff working classification ( p < 0.0001). At 1 month after treatment, there were no significant differences between the OKT3, DSG or ALG group and MP group in cases of borderline change and AR grade I. In cases of grade II and grade III, a significant difference was observed between the OKT3 or ALG group and MP group (p < 0.05). The DSG group showed a slightly better outcome than the MP group, although the difference was not significant. In conclusion, the Banff schema is shown to be valid for classification of acute renal allograft rejection, and it is necessary to determine the treatment for acute rejection according to histopathological classification.

Acute Disease↗