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Biomedical subjects

S Sakai

Publications and source records attributed to S Sakai.

At least 397 records · Page 22Linked to original sources
PubMed1991

Effect of hormones on dissociation of prolactin from the rabbit mammary gland prolactin receptor.

Using microsomes prepared from rabbit mammary gland, the dissociation of prolactin (PRL) from its receptor was determined in the presence of peptide hormones or various concentrations of PRL. Among the hormones tested, PRL (ovine, mouse and bullfrog), human growth hormone and human placental lactogen each accelerated the dissociation of PRL in a manner proportional to their receptor-binding activities. Hormone-dependent dissociation was observed at higher concentrations than those at which the binding of PRL was completely inhibited by lactogenic hormones. In the concentration range 0.1 ng/ml-10 micrograms/ml, PRL increased the rate of dissociation in a logarithmic concentration-dependent manner. It was concluded that the dissociation of PRL from its receptor caused by lactogenic hormones is dependent on the hormone concentration. Arrhenius plot analysis revealed that PRL changed the frequency factor for the dissociation reaction. PRL in the medium inhibited the re-association of dissociated PRL. The data also suggested that PRL regulates the rate of dissociation by interacting with the PRL-receptor complex.

Animals↗
PubMed1991

Focal segmental glomerulosclerosis associated with infantile spasms in five mentally retarded children: a morphological analysis on mesangiolysis.

We report five cases of nephrotic syndrome due to focal segmental glomerulosclerosis (FSGS) in mentally retarded children with severe infantile spasms. Four of the five children diagnosed as West syndrome, Lennox syndrome, or petit mal epilepsy also had cerebral palsy and microcephaly. The other patient had petit mal epilepsy without cerebral palsy and microcephaly. All patients first developed infantile spasms, with the time of onset ranging from 1 week to 2 years of age, and subsequently developed proteinuria, followed by the nephrotic syndrome at 3 to 14 years of age. Four of the five developed terminal renal failure between 7 and 11 years of age. Three subsequently died, but the other underwent kidney transplantation and is still living without further complications. The light, electron microscopic, and immunohistochemical studies performed on the renal biopsies from all the patients and on the autopsy specimens from two cases exhibited FSGS-like lesions. Besides segmental hyalinosis, differing degrees of mesangiolysis were seen, which sometimes developed into dissecting microaneurysms of the glomerular capillary loops. The clinical picture described can be differentiated from congenital nephrotic syndrome (CNS) or infantile nephrotic syndrome (INS) with respect to the age of onset, outcome, and morphological appearance. We reviewed the previous literature and extended earlier observations about an unusual association between the nephrotic syndrome due to FSGS-like lesion, mental retardation, infantile spasms, and/or microcephaly in children.

Adolescent↗
PubMed1991

Combined therapy for maxillary sinus carcinoma with special reference to extensive Denker's operation.

A statistic analysis of 372 patients with maxillary sinus carcinoma treated between 1972 and 1983 was undertaken. One hundred eight patients were treated with the combined method consisting of 50 Gy irradiation, 2,000 mg 5-FU intraarterial infusion and tumor reduction surgery, the so-called extensive Denker's operation. Two hundred twenty-two patients were treated with the combined method not including extensive Denker's operation, and the other 42 patients with radiotherapy alone. The 5-year survival of these three groups were 48, 43, and 17%, respectively. The cumulative local control of the two groups with and without extensive Denker's operation was 51 and 33%, respectively. Maxillectomy as the second treatment was performed in 24 cases (22%) and 71 cases (32%) of the two groups of the combined method with and without extensive Denker's operation, respectively. On the other hand, 5-year survivors without maxillectomy of the two groups were 41 cases (38%) and 54 cases (24%), respectively. It was concluded that extensive Denker's operation plays an important role to increase the success rate of the initial treatment, decrease the rate of maxillectomy and increase the survival rate although it has a certain limit for the indication.

Adult↗
PubMed1991

Ca2+ channel blocking effects of hirsutine, an indole alkaloid from Uncaria genus, in the isolated rat aorta.

Ca2+ channel blocking activity of hirsutine and its pharmacological features were studied. Hirsutine (10(-6) to 3 x 10(-5) M) produced a dose-dependent relaxation of the isolated rat aorta contracted by norepinephrine and high K+ concentration. This effect was exhibited in the aorta strips with or without the endothelium, suggesting an involvement of vasodilative mechanisms not dependent on the endothelium. Hirsutine also inhibited the contractions induced by serotonin and Ca2+ channel activator YC-170, but not by Ca2+ ionophore A23187. The pA2 value of hirsutine was 6.6 +/- 0.1 (mean +/- S.E.; n = 4) in antagonizing cumulative dose-response curve for Ca2+ in the depolarized aorta strips. It is concluded that hirsutine apparently exhibits Ca2+ channel blocking activity mainly through inhibition of the voltage-dependent Ca2+ influx.

Alkaloids↗
PubMed1991

Cheek flaps for reconstruction of full-thickness lip defects.

Two patients with full-thickness defect of the lip reconstructed by a cheek flap are presented. The cheek flap was split into two flaps preserving subcutaneous vascular networks, one for external skin cover and the other for coverage of the oral lining. With this flap, an adequate intraoral vestibulum and easy denture-fitting could be maintained. Disadvantages of the flap described here are that whiskered men cannot use this flap for coverage of the oral lining, and that this cheek flap cannot be used for the reconstruction of full-thickness defects of the lower lip due to potential postoperative downward tendency, unless a simultaneous sling procedure or sphincter reconstruction is performed.

Aged↗
PubMed1991

[A study on the beta-lactamase production for Neisseria gonorrhoeae and the sensitivity to various antibacterial agents].

During the 10-year period from 1980 through 1989 using gonococci isolated in Sapporo, we studied beta-lactamase production capacity and the sensitivity of various antibacterial agents and obtained the following results. 1. The frequency of isolating beta-lactamase producing gonococci (PPNG) displayed a gradual tendency to increase during the first half of the 80's and reached a peak in 1985 of 23.9% (61/255). However, thereafter it tended to decline and in 1989 it was 6.3% (2/32). 2. The sensitivity to penicillin-type antibacterial agents was higher against PPNG than non-PPNG against PCG, ABPC, and AMPC displaying about a 7 level MIC90 so that it was quite sensitive. Against CVA/AMPC, SBTPC it showed a relatively favorable MIC90. Also, the sensitivity of PPNG against AMPC with 1984 as the boundary, thereafter the MIC distribution was observed to decline somewhat. 3. Against the monobactam-type injectable drug, AZT, both non-PPNG and PPNG showed a low MIC distribution and against SPCM both showed a relatively high MIC distribution of 3.13-25 micrograms/ml. 4. In regard to the sensitivity to cephem-type antibacterial agents, against such 3rd generation injectables as CZX, CFTM-PI, etc. it displayed a particularly low MIC distribution. 5. Against tetracycline and macrolide antibacterial agents, it displayed a relatively high MIC distribution. 6. Against new quinolone type antibacterial agents, regardless of being non-PPNG or PPNG, it showed a low MIC.

Anti-Bacterial Agents↗
PubMed1991

Ultrastructure of the endolymphatic sac in the mouse.

The ultrastructure of the endolymphatic sac (ES) in the mouse was examined by light and electron microscopy. This organ was divided into three parts: proximal, intermediate and distal. In the proximal portion of the ES, the epithelium consisted of thin squamous cells. The epithelial cells had acquired basolateral processes, numerous small vesicles and well-developed Golgi apparatus. In the intermediate portion, the epithelium consisted of columnar or cuboidal cells. The epithelial cells could be classified into two types: type I and type II. The type I cells had abundant microvilli, pinocytotic vesicles, vacuoles, multivesicular bodies, lysosomes and mitochondria. The type II cells had fewer numbers of these organelles. A few free-floating cells could be observed in the lumen of this intermediate portion, most of which were macrophages. In the distal portion, the epithelium consisted of squamous or cuboidal cells. The epithelial cells had a few cytoplasmic organelles. In the ultrastructural study, each portion of the mouse ES was found to have a very distinct morphological feature. It was suggested that each of these three portions has a different function.

Animals↗
PubMed1991

Capillary permeability and basolateral endocytic pathway of the epithelium in the mouse endolymphatic sac in vivo.

The capillary permeability and the basolateral endocytic pathway of the mouse endolymphatic sac (ES) epithelium were examined in vivo using intravenous injection of horseradish peroxidase (HRP). The capillaries of the ES were classified as either fenestrated or non-fenestrated. Because dense reaction products were observed soon after injection of HRP in macrophages near both types of capillaries, they were both considered to be permeable to macromolecules. In non-fenestrated capillaries, the basement membrane and small vesicles of the endothelium of the ES were stained with reaction product. These non-fenestrated capillaries were considered to be of muscle type. After 15 min, ES epithelial cells absorbed HRP basolaterally, and the multivesicular bodies and lysosomes of epithelial cells were stained with reaction product. The process of basolateral absorption in the ES epithelium was similar to that in the intestinal epithelium. Our results provide further evidence that the ES is a metabolically active organ which plays an important role in fluid transport in the inner ear.

Absorption↗
PubMed1991

Effect of aldosterone antagonist on the DC potential in the endolymphatic sac.

The effect of aldosterone and canrenoate, known as an aldosterone antagonist, on the DC potential in the endolymphatic sac (ESP) was examined in the guinea pig. Intravenous administration of aldosterone (1 mg/kg) induced no change in the ESP for 60 minutes after the injection. However, canrenoate, an aldosterone antagonist, produced a dose-dependent decrease in the ESP. Pretreatment with aldosterone attenuated the decrease in the ESP by canrenoate. The results suggest the possibility that aldosterone may play a role in the endolymph absorption of the endolymphatic sac.

Aldosterone↗
PubMed1991

Check-valve mechanism as a cause of bilateral spontaneous pneumothorax complicating bronchioloalveolar cell carcinoma.

We present a rare case of simultaneous bilateral pneumothorax complicating bronchioloalveolar cell carcinoma. Autopsy revealed that numerous subpleural alveolar spaces were distended and most of the small airways were narrowed by cancer cells. We conclude that a check-valve mechanism may be responsible for pneumothorax in patients with bronchioloalveolar cell carcinoma.

Adenocarcinoma, Bronchiolo-Alveolar↗
PubMed1991

Chest CT combined with artificial pneumothorax: value in determining origin and extent of tumor.

To determine the presence of chest wall and mediastinal invasion by lung cancer and to establish the origin of chest tumors, we studied 12 patients with intrathoracic tumors by using chest CT combined with artificial pneumothorax. Six patients had primary lung cancer, two had metastases, and one each had neurofibroma, pericardial cyst, chondroma of the rib, and malignant mesothelioma. All 12 tumors abutted the chest wall or mediastinum and could not be separated by conventional CT. Between 400 and 800 ml of air was injected into the pleural space before a second CT scan was obtained. No invasion was found at surgery in cancers that were separated from chest wall or mediastinum on CT scans. Surgery revealed chest wall invasion in three patients in whom the CT scans showed that the tumor was not separated from the chest wall. Only one patient with a tumor that was not separated from the mediastinum on CT did not have mediastinal invasion: in this case, only adhesions were found at surgery. Thus, in the eight patients with primary lung cancer and metastasis, sensitivity, specificity, and accuracy were 100%, 80%, and 88%, respectively. In four patients with mediastinal or pleural tumor, CT combined with pneumothorax was useful for establishing the origin of tumors. In all, 11 of the 12 patients were correctly evaluated by using this method. No complications occurred, except for mild chest discomfort in one patient. This study suggests that chest CT combined with artificial pneumothorax is useful for the evaluation of the extension of lung cancer into the chest wall and mediastinum and for the diagnosis of the site of origin of intrathoracic tumors.

Adult↗
PubMed1991

Response of the endolymphatic sac d.c. potential to asphyxia.

The effect of asphyxia on the endolymphatic sac d.c. potential (ESP) was examined in the guinea pig. Asphyxia was caused for 1.5 min by stopping the respirator. The ESP decreased in amplitude during asphyxia. After the termination of asphyxia the ESP showed a diphasic recovery pattern. When respiration was resumed, the ESP decreased again following a transient recovery. Thereafter, the ESP showed a gradual recovery. beta-blocker (propranolol) inhibited a temporary decrease in the ESP after the resumption of respiration, but not alpha-blocker (phentolamine). The result indicates that the ESP decrease after the resumption of respiration is induced by beta-adrenergic action.

Action Potentials↗
PubMed1991

The effect of acetazolamide on the endolymphatic sac DC potential.

The effect of acetazolamide known as a potent carbonic anhydrase inhibitor of the endolymphatic sac DC potential (ESP) was examined in the guinea pig. Intravenous administration of acetazolamide produced a dose-dependent decrease in ESP amplitude at doses of less than 10 mg/kg. The effect of acetazolamide on ESP was saturated at doses exceeding 10 mg/kg. The maximum reduction of ESP induced by acetazolamide was approximately 50% of the original ESP amplitude. The results suggest that carbonic anhydrase is involved in the generation of ESP.

Acetazolamide↗
PubMed1991

[The role of extensive Denkers operation in combined therapy for maxillary sinus carcinoma].

We had a total of 372 patients with maxillary carcinoma in the period from 1972 to 1983. 108 patients were treated with 50Gy irradiation, intraarterial infusion of 2000 mg 5-FU and extensive Denker's operation in combination. 222 patients were treated with 50 Gy. irradiation and intraarterial infusion of 2000 mg 5-FU. The remaining 42 patients were treated with radio-therapy alone. The 5-year survival in these three groups was 48%, 43%, and 17%, respectively. The cumulative local control of the two former groups was 51%, and 33%, respectively. Total maxillectomy was performed as a second treatment only in 24 of 108 patients (22%) of the first group. Nine of them survived for 5 years and 15 died. On the other hand, 84 of 108 patients not treated with total maxillectomy consisted of 41 five year survivors and 43 deads. From the above, we believe that extensive Denker's operation plays a role to increase success rate of initial treatment, decrease in the necessity of total maxillectomy and improve survival rate, but its indication is limited.

Carcinoma, Squamous Cell↗