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Biomedical subjects

M Yamaguchi

Publications and source records attributed to M Yamaguchi.

At least 1,189 records · Page 66Linked to original sources
PubMed1991

Simulated weightlessness and bone metabolism: impairment of insulin effect on alkaline phosphatase activity in bone tissue.

The effect of simulated weightlessness on bone alkaline phosphatase was investigated after skeletal unloading for up to 4 days. The skeletal unloading was designed by using the model of hindlimb hang in rats. The femoral-diaphyseal fragments obtained from rats bred with skeletal unloading were cultured for 24 h at 37 degrees C in 5% CO2/95% air in Dulbecco's Modified Eagle Medium (high glucose). The bone alkaline and acid phosphatase activity were significantly decreased by skeletal unloading. When the bone tissue was cultured with synthetic [Asu1,7] eel calcitonin (3 and 30 nM), the hormone caused a significant increase of alkaline phosphatase activity in the bone tissues from rats with normal and skeletal-unloading. In culture with insulin (1.0 and 10 nM), skeletal unloading impaired the effect on insulin to increase bone alkaline phosphatase activity. Meanwhile, the culture with zinc sulfate (10 and 100 microM), which can increase bone protein synthesis, caused a remarkable elevation of alkaline phosphatase activity in the bone tissues form rats with normal and skeletal-unloading. Insulin (10 nM) did not alter the zinc effect. These findings suggest that the skeletal unloading with hindlimb hang causes the impairment of insulin's effect to increase alkaline phosphatase activity in the femoral diaphysis of rats, although the effects of calcitonin and zinc were not altered.

Alkaline Phosphatase↗
PubMed1991

Effect of estrogen on bone metabolism in tissue culture: enhancement of the steroid effect by zinc.

The present investigation was undertaken to clarify the effect of estrogen (17 beta-estradiol) on bone metabolism in tissue culture. Calvariae were removed from weanling rats (3-week-old females) and cultured for periods up to 96 h in Dulbecco's Modified Eagle Medium (high glucose, 4500 mg/dl) supplemented with antibiotics and bovine serum albumin. The experimental cultures contained 10(-10) to 10(-8) M estrogen. All cultures were incubated at 37 degrees C in 5% CO2/95% air. Bone calcium content was significantly increased by the presence of 10(-10) to 10(-8) M estrogen. The steroid (10(-10) to 10(-8) M) also significantly increased alkaline phosphatase activity in the bone, whereas it did not significantly alter acid phosphatase activity. No appreciable effect on bone alkaline phosphatase activity was produced with 17 alpha-estradiol (10(-9) and 10(-8) M). Tamoxifen (10(-6) M), an anti-estrogen, completely blocked the effect of estrogen (10(-9) M) of increasing bone alkaline phosphatase activity. Furthermore, bone DNA content was significantly increased by 10(-10) to 10(-8) M estrogen. Meanwhile, the presence of 10(-4) M zinc, which can stimulate bone protein synthesis, significantly enhanced the effect of 10(-9) M estrogen to increase DNA content in rat calvaria, while the metal did not enhance the steroid effect on bone calcium content and alkaline phosphatase activity. The presence of 10(-7) M cycloheximide completely prevented the stimulatory effect of estrogen (10(-9) M) on calcium content, alkaline phosphatase activity, and DNA content in rat calvaria. The present study demonstrates that estrogen has a direct stimulatory effect on bone metabolism in tissue culture and that zinc can enhance the steroid effect on bone DNA.

Alkaline Phosphatase↗
PubMed1991

Simulated weightlessness and bone metabolism: evidence for direct gravitational effect and its related insulin action.

The effect of simulated weightlessness on bone metabolism was investigated in skeletal unloading for 4 days. Skeletal unloading was designed using the model of hind-limb hang in rats. In hypokinetic state, rats were fed while the right hind limb was weighed down and the left hind limb was unloaded (a state of weightlessness). Bone metabolism in normal rats did not vary significantly in the femoral diaphysis in right and left hind limb. Alkaline phosphatase activity and DNA content in the femoral diaphysis were not significantly altered by hypokinetic state without skeletal unloading, while the unloading caused an appreciable decrease in the enzyme activity and DNA content. However, femoral-diaphyseal zinc content and glucose consumption was significantly decreased by hypokinetic state with and without skeletal unloading. When femoral-diaphyseal tissues were cultured in the presence of insulin (10 nM), the hormone produced a significant increase of alkaline phosphatase activity and decrease of glucose consumption in the femoral-diaphyseal tissues obtained from normal and hypokinetic rats. This hormonal effect was not seen in bone tissues from hypokinetic rats with skeletal unloading. These results suggest that skeletal unloading-induced disorder of bone metabolism is directly related to gravitational effect and that gravitational stimulation may be involved in insulin action.

Alkaline Phosphatase↗
PubMed1991

Short-term treatment with 17-beta estradiol enhances spontaneous [3H] dopamine release from cultured rat tuberoinfundibular neurons.

The effects of 17-beta estradiol (E2) on spontaneous [3H] dopamine ([3H]DA) release was investigated using primary cultured cells from the tuberoinfundibular region of rat hypothalamus, which includes DA neurons. [3H] DA uptake by the neurons in the presence of E2 at 10(-8) mol/l was similar to that by control cells. Pretreatment with E2 at 10(-9) mol/l or more resulted in dose-dependent increase in spontaneous [3H] DA release from the cultured hypothalamic cells. The spontaneous [3H] DA release reached almost a plateau on pretreatment with E2 at 10(-9) mol/l for 6 hours. Pretreatment with 1 nM E2 also enhanced DA release induced by 10 microM ionophore A23187. These results indicate that estrogen stimulates tuberoinfundibular DA neuronal activity.

Animals↗
PubMed1991

The interferon family stimulates the secretions of prolactin and interleukin-6 by the pituitary gland in vitro.

The effects of interferon-alpha, interferon-beta 1 and interferon-gamma on the secretions of prolactin (PRL) and interleukin-6 by primary cultured rat anterior pituitary cells were examined. These three interferons caused dose-dependent increases in PRL secretion within 30 min, and dose-dependent stimulation of interleukin-6 were weaker than the effects of interleukin-1 and tumor necrosis factor-alpha. These results suggest that interferons regulate PRL secretion from the pituitary gland, and that there may be a pathway in which interferons stimulate PRL secretion through interleukin-6 release.

Analysis of Variance↗
PubMed1991

Pulmonary origin of left anterior descending coronary artery in tetralogy of Fallot.

We report the case of a 4-year-old girl with an anomalous origin of the left anterior descending coronary artery from the pulmonary artery in association with tetralogy of Fallot. Creation of an intrapulmonary tunnel from a newly created aortopulmonary window to the coronary ostium in the pulmonary trunk and total repair of tetralogy of Fallot were successfully carried out. The advantage of intrapulmonary tunnel technique (Takeuchi method) for this very rare combination is stressed.

Child, Preschool↗
PubMed1991

The use of omental pedicle flap for tracheobronchial reconstruction in infants and children.

For the surgical repair of long-segment tracheal stenosis, costal cartilage graft or extensive resection with end-to-end anastomosis has often been used. Both procedures have a risk of developing anastomotic leakage, which is potentially a lethal complication, or stenosis resulting from compromised blood supply to the tissue at the anastomosis. We have used omental pedicle flap (OPF) to seal the anastomotic line and to restore the vascularity of the graft and the trachea in an attempt to avoid fatal complications. During the period between 1986 and 1990, OPF technique was used in tracheobronchial reconstruction in six patients aged 4 months to 3 years; cartilage graft for extensive tracheal stenosis (4), tracheal resection and anastomosis (1), and bronchial resection and anastomosis (1). The omentum was separated from the colon to form an OPF with the right gastroepiploic vessels preserved. The OPF was brought to the upper trachea in the mediastinum through the retrosternal space. There was no immediate postoperative death due to anastomotic leak. Endotrachial tubes were removed in all patients. Four of the six are totally free of airway problems. One patient showed persistent stridor because of remaining stenosis at the cervical trachea. The remaining one patient who underwent bronchial resection developed anastomotic stenosis probably due to the compression of the floppy left main bronchus by adjacent aorta. The OPF seems to be an important surgical adjunct in order to eliminate fatal complications in tracheobronchial reconstruction.

Bronchi↗
PubMed1991

Stimulatory effect of calcitonin on Ca2+ inflow in isolated rat hepatocytes.

The effects of synthetic [Asu1,7]eel calcitonin (CT) on the unidirectional inflow of Ca2+ were investigated in isolated rat liver cells by measuring the initial rate of 45Ca2+ uptake. CT increased Ca2+ inflow, with EC50 values (concentrations giving half-maximal effect) of 10(-10) M. The action of CT was in evidence within 15 s after the addition of 45Ca2+ to the cells. CT-activated Ca2+ inflow was completely blocked by the presence of the Ca2(+)-antagonist verapamil at a concentration of 10(-8) M. Meanwhile, epinephrine (10(-8) to 10(-4) M) or phenylephrine (10(-8) to 10(-4) M) increased Ca2+ inflow within 60 s after the addition of 45Ca2+ to the cells. Those hormonal effects were additively enhanced by the presence of CT (10(-8) M). Phorbol 12-myristate 13-acetate (PMA), an activator of protein kinase C, increased Ca2+ inflow at a concentration of 10(-9) to 10(-5) M. The presence of CT (10(-8) M) synergistically enhanced PMA-increased Ca2+ inflow at concentrations of 10(-7) to 10(-5) M. The present results suggest that CT can stimulate the rate of Ca2+ inflow in rat liver cells.

Animals↗
PubMed1991

Surgical treatment of airway obstruction associated with congenital heart disease in infants and small children.

In the last 12 years, 21 patients age 1 month to 5 years (median, 7 months) underwent surgical treatment for severe airway obstruction associated with congenital heart disease. Plico-suspension of the pulmonary artery was carried out in 14 patients with documented severe left bronchial compression by a distended pulmonary artery together with repair of ventricular septal defects (11 patients), repair of large coronary artery fistula (1), division of ductus (1) and pulmonary artery banding (1), with subsequent significant relief of compression. Aortopexy was used in 2 patients with documented severe tracheal compression by a right aortic arch. Five patients had congenital tracheal stenoses (3 extensive, 2 localized). Two of 3 patients with associated complex intracardiac anomalies underwent concomitant repair of both lesions with the use of cardiopulmonary bypass and 1 had a tracheoplasty and pulmonary artery banding. Tracheal reconstruction with a cartilaginous graft together with repair of pulmonary artery sling was carried out in 2 infants. Nineteen patients are alive and well, at a mean follow-up of 87 months. In conclusion, we advocate early aggressive surgical intervention to both lesions to obtain a better result in the management of infants and small children with this difficult and often fatal combination.

Airway Obstruction↗
PubMed1991

Spectrofluorimetric determination of 5-hydroxyindoles with benzylamine or 3,4-dimethoxybenzylamine as a selective fluorogenic reagent.

A spectrofluorimetric method has been developed for the sensitive and selective determination of 5-hydroxyindoles; the method is based on the reaction of 5-hydroxyindoles in a weakly alkaline solution (pH 9.0) with aromatic methylamines in the presence of potassium hexacyanoferrate(III) and dimethyl sulphoxide; the compounds produced fluoresce intensely in an alkaline solution (pH 11-12). Of the eight aromatic methylamines tested, benzylamine and 3,4-dimethoxybenzylamine were found to be the most favourable fluorogenic reagents in terms of sensitivity and reactivity. The methods with benzylamine and 3,4-dimethoxybenzylamine permit the determination of 5-hydroxyindoles at concentrations as low as 22-72 pmol ml-1 and 1.0-2.4 nmol ml-1, respectively.

Benzylamines↗
PubMed1991

Prenatal diagnosis of the aneurysm of the vein of Galen by pulsed Doppler unit.

Aneurysm of the vein of Galen is a rare anomaly. In the severe type, the first clinical manifestation of this anomaly is heart failure after birth. Prenatal diagnosis is important in preventing heart failure during the postnatal period. Here, we report the prenatal diagnosis of a case of aneurysm of the vein of Galen in which we used a pulsed Doppler unit combined with a fetal electrocardiogram-phonocardiogram unit.

Adult↗
PubMed1991

The antihypertensive mechanism of delapril, a newly developed converting enzyme inhibitor, is related to the suppression of vascular angiotensin II release in the spontaneously hypertensive rat.

Accumulating evidence suggests an important role of vascular renin-angiotensin system (RAS) in the local control of arterial tone. To further gain insight into the significance of vascular RAS in hypertension, we investigated the relationship between the antihypertensive action of delapril, a newly developed converting enzyme inhibitor (CEI), and its effects on vascular angiotensin II (Ang II) release in spontaneously hypertensive rats (SHR). Male SHRs were given delapril or its active metabolite (5-hydroxydelapril diacid; 5-hydroxy-DPD) orally (10 mg/kg/day) for 2 weeks. Isolated hind legs of these rats were perfused with angiotensinogen-free Krebs-Ringer solution, and Ang II released into the perfusate was directly determined by extraction with Sep-Pak C18 cartridges connected to the perfusion system. Both delapril and 5-hydroxy-DPD produced a sustained antihypertensive action. The spontaneous release of Ang II from isolated perfused hind legs of control SHRs was about 50 to 110 pg during the first 30 min of perfusion, and it remained stable up to 3 h. Another active metabolite, delapril diacid (DPD), when added to the perfusion medium (10(-9) to 5 x 10(-5) mol/L), suppressed the Ang II release in a dose-dependent manner. The maximal percent inhibition of Ang II released evoked by DPD (5 x 10(-6) mol/L) was approximately 51%. Oral pretreatment of either delapril or 5-hydroxy-DPD for 2 weeks suppressed the Ang II release by 61% and 73% for delapril and 5-hydroxy-DPD, respectively. These results suggest the presence of a functional RAS in vascular tissues, and that delapril exerts its antihypertensive effect through inhibition of vascular Ang II release in SHRs.

Administration, Oral↗
PubMed1991

Ethnicity and family involvement in the treatment of schizophrenic patients.

In a cross-ethnic study of neuroleptic response, the level of family involvement with the treatment of 26 Asian and 26 Caucasian patients was evaluated. Asian family members were intimately involved, Caucasians much less so. These results quantitatively demonstrated the relatively greater importance of working with family members when treating Asian patients. They also indicate that relatively more effort is needed to increase involvement of Caucasian families in the treatment process.

Asia↗
PubMed1991

Genetic study of ossification of the posterior longitudinal ligament in the cervical spine with human leukocyte antigen haplotype.

To evaluate the genetic background of ossification of the posterior longitudinal ligament, the relationship between the presence of absence of ossification and human leukocyte antigen haplotypes was studied in 33 families of patients with ossification of the posterior longitudinal ligament. The study revealed that human leukocyte antigen haplotypes formed certain types of clusters, and that some human leukocyte antigen haplotypes were very rare in the Japanese population, suggesting the involvement of human leukocyte antigen-linked factors in the pathogenesis of ossification of the posterior longitudinal ligament of the cervical spine. In the families of these patients, ossification of the posterior longitudinal ligament was demonstrated by radiography in 56% (10/18) of the siblings. Each of these siblings shared both human leukocyte antigen haplotypes with the patient. None of those who shared only one human leukocyte antigen haplotype with the patient had developed ossification of the posterior longitudinal ligament. From these findings, the presence of both pathogenic human leukocyte antigen haplotypes is considered to be necessary for the development of ossification of the posterior longitudinal ligament, and this genetic predisposition may be activated by multiple factors, including regressive degeneration due to aging and the environment.

Cervical Vertebrae↗
PubMed1991

Organization of mouse DNA polymerase beta gene silencer elements and identification of the silencer-binding factor(s).

Different portions of the 5'-upstream region of the mouse DNA polymerase beta gene were combined with bacterial chloramphenicol acetyltransferase (CAT) gene of the CAT vector. Transfection of these recombinant plasmids into mouse NIH/3T3 cells has revealed that each of the previously identified two negatively acting regions (silencers I and II) of this gene consists of multiple sub-domains. The distal silencer (silencer I) at around -1.5 kb consists of four sub-domains (-1852 to -1667, -1663 to -1616, -1564 to -1525 and -1355 to -1257). The promoter-proximal silencer (silencer II) at around -0.5 kb consists of two functional domains (-681 to -523 and -490 to -447) separated by a neutral region of 33 base pairs. Silencer II functioned efficiently when silencer I was deleted. Conversely, the distal silencer I functioned efficiently when silencer II was deleted. Thus, these silencers functioned redundantly to each other in NIH/3T3 cells. Nucleotide sequence analysis revealed no extensive sequence similarity between these two silencers. Significant sequence similarity is present between a distal portion of silencer II and the c-myc gene silencer, and also between a proximal portion of silencer II and the mouse F9 cell-specific silencer. A protein factor(s) that specifically bound to the silencer elements was detected in nuclear extracts of NIH/3T3 cells and mouse liver in which DNA polymerase beta was expressed at a rather low level. The same binding factor(s) can bind to both silencer I and II regions, although its affinity for silencer II is much higher than that for silencer I.

Animals↗
PubMed1991

Duodenal glands of the pony (Equus caballus).

The ultrastructure and histochemistry of the duodenal glands of the pony (Equus caballus) was examined in four horses. Unlike that of most species except for the rabbit, the submucous glands of the horse contain two distinct cell types, serous and mucous. These cells are described.

Animals↗