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Biomedical subjects

S Sakai

Publications and source records attributed to S Sakai.

At least 289 records · Page 16Linked to original sources
PubMed1994

Oleanolic acid saponins from root bark of Aralia elata.

Three new oleanolic acid glycosides, tarasaponins I-III, were isolated as their methyl esters from the root bark of Aralia elata together with four known glycosides, the methyl esters of chikusetsusaponins IVa, IV, 28-desglucosyl-chikusetsusaponin IV and pseudoginsenoside RT1. Tarasaponins I-III were characterized as oleanolic acid 3-O-[beta-D-glucopyranosyl(1-->3)][alpha-L-arabinofuranosyl(1-->4)[- beta-D-glucuronopyranoside, oleanolic acid 3-O-[beta-D-xylopyranosyl(1-->2)][beta-D-galactopyranosyl(1-->3)]-beta- D-glucuronopyranoside and beta-D-glucopyranosyl oleanolate 3-O-beta-D-galactopyranosyl(1-->3)-beta-D-glucuronopyranoside, respectively.

Carbohydrate Sequence↗
PubMed1994

Characteristics of Na+ current in Schwann cells cultured from frog sciatic nerve.

Characteristics of voltage-dependent currents in cultured frog Schwann cells were investigated by the whole-cell clamp technique. An inward current was detectable at a membrane potential level more positive than -50 mV and reached a maximum value at about -10 mV, while no rectifying channel was present. The inward current was carried by Na+ ions, because the extrapolated reversal potential of the current agreed with the calculated ENa, and the current was sensitive to tetrodotoxin. The membrane potential for half-maximal inactivation was -82 mV. The inactivation curve indicated that more than 90% of the Na+ channels were inactivated at the resting membrane potential, suggesting that the cultured frog Schwann cells could not generate an action potential under physiological conditions. The time constant for the inactivation at a maximum current was 5.3 ms (-10 mV, 13 degrees C). The electrophysiological characteristics of the Na+ current in the cultured frog Schwann cells were compared with those in other tissues. This Na+ current was quantitatively different from that observed in the amphibian node of Ranvier but was similar to that in the mammalian Schwann or glial cells, especially in the more hyperpolarized half-maximal inactivation potential and in the slower inactivation time course.

Animals↗
PubMed1994

A correlation of argyrophilic nucleolar organizer regions with prognoses in patients with maxillary sinus squamous cell carcinoma.

Argyrophilic nucleolar organizer regions (AgNORs) were determined by a semiautomatic image analyzer in a group of 28 patients with T2 or T3 maxillary sinus squamous cell carcinoma. The group was separated into recurrent and non-recurrent groups, metastatic and non-metastatic groups, as well as groups strongly or weakly positive for epidermal growth factor receptor (EGFR). The mean number and area of AgNOR dots per nucleus and the mean size of each dot were calculated. The mean number and area were significantly greater than those in normal cells (P < 0.001), but not in recurrent and non-recurrent groups, metastatic and non-metastatic groups and groups separated by EGFR. There was also no difference found in the mean sizes of tumor and normal cells. These results suggest that AgNOR is related to malignant transformation, but not prognosis.

Aged↗
PubMed1994

Laparoscopic cholecystectomy: a report of 409 consecutive cases and its future outlook.

A retrospective study was conducted on 409 patients who underwent laparoscopic cholecystectomy at Teikyo University Hospital between May, 1990 and October, 1992. The operation had to be converted to an open cholecystectomy in ten of these patients because of uncontrollable bleeding from the cystic artery in one, venous bleeding due to portal hypertension in one, extensive adhesions of the omentum and the duodenum to the gallbladder in two, extensive adhesions around the gallbladder in four, and extensive adhesions between the gallbladder and the common bile duct (CBD) in two. The time taken to complete the procedure ranged from 30 to 235 min, the average time being 81 min, and the postoperative hospital stay ranged from 3 to 56 days, the average stay being 6.5 days. Eleven patients developed complications intra- or postoperatively: bile duct injury which became manifest after the operation and required laparotomy in three patients; injury to the right hemidiaphragm resulting in a right pneumothorax in one; periumbilical subcutaneous emphysema in one; mild bile leaks which resolved in a few days in two; and a severe bile leak which resolved after 6 days in one. The indications for laparoscopic cholecystectomy have widened with experience and now, CBD stones and a history of previous gastrectomy are no longer contraindications for laparoscopic cholecystectomy. Thus, it seems that laparoscopic cholecystectomy can be performed as safely as a standard cholecystectomy, provided the patients are selected properly and appropriate caution is exercised.

Adolescent↗
PubMed1994

Mineralocorticoid type I receptor in the rat cochlea: mRNA identification by polymerase chain reaction (PCR) and in situ hybridization.

Expression of mineralocorticoid type I receptor (MR) gene in the rat cochlea was determined using molecular biological techniques. We synthesized complementary DNA (cDNA) from rat cochlear total RNA and then amplified MR cDNA fragments by polymerase chain reaction (PCR). The amplified cDNA fragments were subcloned into an expression vector and the nucleotide sequence was analyzed to confirm the expression of mRNA encoding MR in the cochlea. We then synthesized digoxigenin-labeled riboprobes with this cloned DNA template and examined the localization of MR mRNA in the cochlea by in situ hybridization. The amino acid sequence of MR cDNA expressed in the cochlea was identical to that of the MR first cloned in the rat hippocampus. In situ hybridization showed the expression of MR mRNA in marginal cells of the stria vascularis, suggesting that aldosterone may regulate microhomeostasis of the endolymph, presumably by modulating Na, K-ATPase activity. Intense MR signal was also identified in spiral ganglion cells, the function of which remains to be determined.

Aldosterone↗
PubMed1994

Oleanolic acid saponins from root-bark of Aralia elata.

Five new oleanolic acid glycosides, tarasaponins III-VII, were isolated from the dried root-bark of Aralia elata together with stipuleanoside R2, in addition to eight saponins previously reported. They were characterized as oleanolic acid 3-O-[beta-D-xylopyranosyl(1-->2)] [beta-D-glucopyranosyl(1-->3)]-alpha-L-arabinopyranoside, beta-D-glucopyranosyl oleanolate 3-O-[beta-D-glucopyranosyl(1-->2)][alpha-L-arabinofuranosyl (1-->4)]-beta-D-glucuronopyranoside, beta-D-glucopyranosyl oleanolate 3-O-[beta-D-xylopyranosyl(1-->2)][beta-D-galactopyranosyl (1-->3)]-beta-D-glucuronopyranoside, beta-D-glucopyranosyl oleanolate 3-O-[beta-D-xylopyranosyl(1-->2)][beta-D-glucopyranosyl (1-->3)-alpha-L-arabinopyranoside, respectively.

Carbohydrate Sequence↗
PubMed1994

The contact Nd-YAG laser for oral and oropharyngeal malignant tumors.

Nine oral and oropharyngeal squamous cell carcinomas were removed with a contact Nd-YAG laser. Clinical and morphological studies on wound healing and effects of the Nd-YAG laser were performed. The wounds were not sutured and patients did not complain of any severe symptoms. The wound healing was prolonged to 3-6 weeks. Cells and glands degenerated at a depth of 2-3 mm by the direct effects of the laser. The epithelium exhibited acantholysis 5 mm from the site of laser injury. Scanning electron microscopy showed no coagulation or other coated material in the wound created by a surgical knife, while the wound surface by laser consisted of carbonization, well-coated and non-coated areas. These findings varied with the laser power. The coagulation and thermal effects of the Nd-YAG laser resulted in autolysis of tumor cells at least within 5 mm of the cutting surface. The contact Nd-YAG laser was useful for the removal of the malignant tumor in the oral cavity and oropharynx where it is difficult to maintain a generous safety margin.

Adult↗
PubMed1994

Comparison of the binding of beta-cyclodextrin and alpha- and gamma-cyclodextrins with pullulanase from Klebsiella pneumoniae as studied by equilibrium and kinetic fluorometry.

The change in fluorescence spectra of crystalline pullulanase from Klebsiella pneumoniae caused by the addition of alpha-, beta-, and gamma-cyclodextrins and 6-O-alpha-glucosyl-alpha-cyclodextrin and 6-O-alpha-glucosyl-beta-cyclodextrin was investigated at 25 degrees C and pH 5.6. The fluorescence intensity at around 325 nm (excitation at 280 nm) was increased by the addition of all the cyclodextrins studied. The dissociation constant, Kd, of the enzyme-cyclodextrin complex was evaluated by fluorometric titration for each cyclodextrin, and was consistent with the inhibitor constant, Ki, obtained previously [Iwamoto et al. (1993) J. Biochem. 113, 93-96]. The Kd values of beta-cyclodextrin and 6-O-alpha-glucosyl-beta-cyclodextrin were approximately two orders of magnitude smaller than those of alpha- and gamma-cyclodextrins. Fluorescence titration of a cyclodextrin in the presence of another cyclodextrin revealed competition among alpha-, beta-, and gamma-cyclodextrins for binding with the enzyme, which indicates that the binding region of beta-cyclodextrin overlaps those of alpha- and gamma-cyclodextrins. On the other hand, with excitation at 295 nm, a fluorescence spectral change similar to that excited at 280 nm was observed for alpha- and gamma-cyclodextrins and 6-O-alpha-glucosyl-alpha-cyclodextrin, whereas beta-cyclodextrin and 6-O-alpha-glucosyl-beta-cyclodextrin did not show any such change. These results suggest that the binding site or the binding mode of beta-cyclodextrin is slightly different from those of alpha- and gamma-cyclodextrins.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacterial Proteins↗
PubMed1994

Antianginal effects of FK409, a new spontaneous NO releaser.

1. The aim of this study was to compare antianginal effects of (+/-)-(E)-ethyl-2-[(E)-hydroxyimino]-5-nitro-3-hexeneamide (FK409), a new spontaneous nitric oxide releaser, with those of isosorbide dinitrate (ISDN). We used two types of rat angina model; methacholine- and arginine vasopressin (AVP)-induced coronary vasospasm models. 2. In the in vitro study, FK409 showed 80 times more potent vasorelaxant effect in dog isolated coronary artery than ISDN (EC50 = 16.7 +/- 4.8 and 1340 +/- 320 nM, respectively). 3. In the rat methacholine-induced coronary vasospasm model, FK409 suppressed the elevation of ST segment dose-dependently and significantly at 0.1 mg kg-1, i.d. On the other hand, ISDN suppressed it significantly at 3.2 mg kg-1, i.d. In addition, the efficacy of 3.2 mg kg-1 ISDN in the model was almost the same as that of 0.1 mg kg-1 FK409. 4. In the above experiments, FK409 and ISDN decreased mean blood pressure significantly at the maximum dose tested (1.0 mg kg-1, i.d. and 3.2 mg kg-1, i.d., respectively) but did not change heart rate at these doses. Therefore, the hypotensive effect of FK409 was 10 times weaker than the antianginal effect of the compound, while those of ISDN were almost the same. 5. In the rat AVP-induced coronary vasospasm model, 32 mg kg-1 FK409 significantly inhibited the depression of ST segment 60 min after oral administration. On the other hand, 32 mg kg-1 ISDN did not inhibit it at 60 and 120 min after oral administration. 6. In conclusion, FK409 inhibits coronary vasospasm more potently in two types of rat angina models than ISDN. In addition, FK409 shows an antianginal effect more selectively that a hypotensive effect,compared with ISDN.

Angina Pectoris, Variant↗
PubMed1994

Effects of prostacyclin and beraprost on ciliary motility of rabbit airway epithelium.

The effects of prostacyclin and its stable analog beraprost on ciliary beat frequency (CBF) of rabbit tracheal epithelium were studied by a microphoto-oscillation technique in vitro. Addition of these drugs increased CBF in a dose-dependent fashion: the maximal increase from the baseline value and the drug concentration required to produce a half-maximal effect were 13.3 +/- 2.0% (p < 0.05) and 1.8 +/- 0.4 x 10(-7) mol/l for prostacyclin and 30.8 +/- 3.4% (p < 0.001) and 1.6 +/- 0.5 x 10(-7) mol/l for beraprost. These effects were accompanied by the increase in intracellular cyclic AMP levels. Thus, prostacyclin and beraprost may stimulate ciliary motility and, hence, mucociliary transport through the production of cyclic AMP.

Animals↗
PubMed1994

Endobronchial mucosal bridges as evidence of residual malignancy.

Three patients who exhibited endobronchial mucosal bridges that formed at the site of tumor regression following chemotherapy for small cell lung carcinoma are presented. Histopathologic examination showed residual malignant cells in 2 of the 3 patients within the submucosal fibrous tissue and an overlying benign epithelium. Although these mucosal bridges were previously thought to represent a complete remission following chemotherapy or radiotherapy for small cell lung carcinoma, they may, in fact, harbor a residual malignancy under the benign mucosa.

Aged↗
PubMed1994

Antinociceptive and antipyretic effects of alkaloids extracted from the stem bark of Hunteria zeylanica.

Effects of crude alkaloids extracted from the stem bark of Hunteria zeylanica Gard. (H. zeylanica) on nociceptive responses, capillary permeability, yeast-induced hyperthermia, pentobarbital-induced sleep, and spontaneous motor activity were investigated. Oral administration of 50 mg/kg H. zeylanica alkaloid extract significantly decreased the number of writhings induced by intraperitoneal acetic acid. The extract at 100-200 mg/kg significantly increased nociceptive threshold of the inflamed but not the non-inflamed paw in the Randall-Selitto test. Moreover, in the formalin test, the extract (100 mg/kg) significantly decreased licking activity in the late phase without affecting the activity in the early phase. However, the extract did not produce antinociceptive effect in the hot plate test, while it inhibited increase of vascular permeability induced by acetic acid in the capillary permeability test. Moreover, the extract dose-dependently reduced yeast-induced hyperthermia in rats without affecting normothermia. It did not affect pentobarbital-induced sleep, but significantly increased locomotor activity at 100 mg/kg. These results suggest that H. zeylanica alkaloid extract possesses antinociceptive and antipyretic effects, and that the former effect may be mediated by its anti-inflammatory action.

Acetates↗
PubMed1994

Interbronchoscopist variability in the diagnosis of lung cancer by flexible bronchoscopy.

STUDY OBJECTIVE: We evaluated the interbronchoscopist variability in the diagnosis of lung cancer by flexible bronchoscopy. DESIGN AND SETTING: A retrospective review of the bronchoscopic records and clinical charts of patients at a university-affiliated hospital. PATIENTS AND MEASUREMENTS: All records of flexible bronchoscopic procedures performed for the diagnosis of lung cancer were retrospectively reviewed, and procedures that obtained histologic or cytologic evidence of malignancy were considered positive. Rates of positivity were compared according to the following factors: operator, operator experience, bronchoscopic findings, tumor location, and tumor laterality. Factors that affected the positivity rate were evaluated using logistic regression analysis. RESULTS: Of 384 bronchoscopic procedures performed in 353 patients, 275 (72 percent) were positive. The positivity rate differed significantly depending on the operator (p = 0.003) and the bronchoscopic findings (p < 0.001). A difference between operators was noted in technically difficult cases without epithelial or subepithelial findings and when tumors were located in the upper lobe or the superior segment of the lower lobe. The bronchoscopic findings and the operator also emerged as factors significantly affecting the positivity rate in the logistic analysis. CONCLUSIONS: The diagnostic yield of bronchoscopy for lung cancer is dependent on both the type of bronchial lesion present and the bronchoscopist.

Bronchoscopy↗
PubMed1994

Rupture of thoracic aorta caused by penetrating aortic ulcer.

We present the findings in a 57-year-old man with a rupture of the thoracic aorta that originated in a penetrating atherosclerotic aortic ulcer. It formed a large hematoma that clinically mimicked a true saccular thoracic aneurysm. The possibility of penetrating aortic ulcer should be considered in the differential diagnosis of aortic aneurysm.

Aortic Aneurysm, Thoracic↗
PubMed1994

Characterization of plasma and intracellular membrane prolactin receptor in lactating mouse mammary cells.

Mammary cells were prepared from lactating mice by collagenase digestion in order to examine the reaction of prolactin (PRL) with its cellular receptors. Cells were treated with 10% acetic acid following PRL binding. Between 5 and 12.5% acetic acid, the dissociation of PRL remained constant. The ratio of dissociated PRL was comparable to that of tissue slices or disrupted cells with this treatment. In subcellular membranes, about 81% of PRL bound to plasma membrane receptors was dissociated by acid treatment while PRL dissociated from intracellular membrane receptors was about 21%. Based on the nature of their PRL dissociation, PRL receptors were classified as acid-sensitive or acid-insensitive. The reaction of PRL with either species was reversible and saturable, and was dependent on temperature and time. Both species showed high PRL-binding affinity. However, acid-insensitive receptor was unstable at 37 degrees C. The level of acid-sensitive receptor was close to that of acid-insensitive receptor in late pregnancy. During the first 3 days of lactation, the level of acid-sensitive receptor increased more slowly than that corresponding to acid-insensitive receptor. The above criteria suggest that the postpartum increase in PRL binding is characterized especially by an increase in the level of acid-insensitive PRL receptor located mainly on intracellular membrane.

Acetates↗
PubMed1994

Absorption activity and barrier properties in the endolymphatic sac. Ultrastructural and morphometric analysis.

A constant volume of horseradish peroxidase (HRP) was injected directly into the endolymphatic sac (ES) lumen of the guinea pig to investigate the detailed absorption activity and the barrier properties of the ES. The reaction products were analyzed using an ultrastructural and morphometric method 1 to 10 h after the injection of this tracer. The epithelial cells in the proximal portion did not absorb the intraluminal HRP at any intervals after the tracer injection. The epithelial cells of the intermediate portion were classified clearly into two types according to their absorption activity: active-absorptive, and non-active cells. Uptake in the active-absorptive cells reached its maximal rate 8 h after the injection and then decreased. The active-absorptive cells in teh intermediate portion are considered to play a major role in the macromolecular absorption in the ES epithelium. The non-active cells scarcely absorbed the intraluminal HRP, suggesting that these cells are not involved in the macromolecular absorption. The absorption activity in the distal portion was lower than that in the active-absorptive cells in the intermediate portion 1 to 8 h after the HRP injection, while higher 10 h after the injection. Not only the intermediate portion but also the distal portion may play an active role in the macromolecular absorption. In no portion of the ES did intraluminal HRP penetrate beyond the junctional complexes between epithelial cells or through the cytoplasm. It is conceivable that there is a tight barrier to the intraluminal macromolecules in the epithelial linings of the ES.

Absorption↗
PubMed1994

Negative cooperativity in the prolactin-receptor interaction in the rabbit mammary gland: action of high prolactin concentration.

The concentration of serum prolactin in the lactating mother is elevated by milking, and the dissociation of prolactin from the receptor is accelerated by the presence of prolactin in vitro. The interaction of prolactin at high concentrations with the receptor was examined using lactating rabbit mammary microsomes. At low concentrations of prolactin, the Scatchard plots were linear. At concentrations > 30 ng/ml, however, the slope of the Scatchard plot line changed. The Hill coefficient decreased from 1.09 to .77 or from .80 to .65 as prolactin concentrations increased. When a receptor preloaded with prolactin was utilized, prolactin at concentrations > 20 ng/ml associated with the receptor in a concentration-dependent manner. The Hill coefficient of this reaction was .70. The receptor remained intact for re-association after prolactin-induced dissociation. These data indicate that, because of the presence of negative cooperativity, prolactin at exceedingly high concentrations greatly accelerates the prolactin-binding reaction. The elevation of serum prolactin induced by milking may be important in the maintenance of active milk synthesis.

Animals↗