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S Shibasaki

Publications and source records attributed to S Shibasaki.

At least 37 records · Page 2Linked to original sources
PubMed1994

Electron microscopic observation of the transitional portion in the human eccrine sweat gland.

The transitional portion in human eccrine sweat glands was observed by transmission electron microscope (TEM). The transitional portion, consisting of columnar epithelial cells (columnar cells) and basal cells, formed a very short segment about 25 to 50 microns in length. The portion was abruptly connected to the secretory segment, and shifted to the excretory duct without marked ultrastructural changes. The columnar cells were morphologically characterized by small apical vesicles as reported in previous reports. Considering the frequency of the mitosis of the columnar cells, the transitional portion seemed to be one of the areas of cell proliferation in the gland. Basal cells were sparse in the region connecting the secretory segment, but dense near the duct. Basal cells in the secretory segment side of the transitional portion, containing thin microfilament-bundles in the infranuclear cytoplasm, were considered to be immature myoepithelial cells. On its ductal side, however, the basal cells showed morphological profiles similar to ductal peripheral cells. These findings suggest that the differentiation of myoepithelial cells occurs in the transitional portion of eccrine sweat glands.

Adult↗
PubMed1992

Ciliogenesis in the human oviduct epithelium during the normal menstrual cycle.

Ciliogenesis has been investigated in the human oviduct epithelium during the normal menstrual cycle. Both centriolar and acentriolar pathways were involved in the replication of basal bodies. The centriolar pathway, in which procentrioles generate with the aid of preexisting diplosomes, played a minor role in the human oviduct. In the acentriolar pathway, fibrous granules were the first structure which appeared in the course of ciliogenesis and they initially occurred in association with the Golgi apparatus or free ribosomes. Subsequently deuterosomes arose in the aggregates of fibrous granules or apart from fibrous granules, and then microtubules-containing procentrioles originated around deuterosomes. Newly formed centrioles migrated to the apical cytoplasm with accompanying deuterosomes, and ciliary shafts extended first at the periphery of the luminal surface of ciliogenic cells. Deuterosomes as well as fibrous granules were considered to be related to the rootlet formation. Replicaion of basal bodies and protrusion of ciliary shafts mostly occurred during the proliferative phase of the menstrual cycle; however, a small number of fibrous granules indicating the ciliogenesis were still observed in some ciliated cells during the secretory phase. Ciliogenic cells in early stages of ciliogenesis contained secretory granules-like vesicles in the apical cytoplasm, suggesting that the ciliated cells are differentiated from secretory cells in the late secretory phase on demand.

Adult↗
PubMed1990

Ultrastructural study of the ciliated cyst in the human uterine tube epithelium.

Ciliated cysts in the human uterine tube epithelium were investigated with the transmission electron microscope. The cysts were about 3-9 microns in diameter and were provided with many ciliary apparatuses and microvilli. Degenerative changes of these cilia, such as electron-dense round or irregular bodies and amorphous substance, were observed in many cysts, but complete disappearance of ciliary structures was not detected in any ciliated cysts. The ciliated cysts were mostly observed in basal cells and were occasionally found in ciliated cells bordering the tubal lumen. In the basal cells, these cysts distended with the increase in degenerated cilia. Distended ciliated-cyst-containing cells became exposed directly to the tubal lumen. U- or reverse omega-shaped deep indentations of the apical surface of ciliated cells confirmed the opening of ciliated cysts into the lumen. It was suggested that the ciliated cysts result from the premature differentiation of basal cells or disturbed migration of centrioles in ciliogenic cells.

Cell Differentiation↗
PubMed1989

Transport of salicylamide from intestinal lumen to serosal compartment.

This study was aimed to clarify the fate of the perfused drug and the characteristics of the serosal compartment. A portion of rat small intestine immersed in a solution regarded as the serosal compartment was perfused in situ and the permeability of drugs into the mesenteric venous blood and into the serosal solution were determined. The cumulative amounts of salicylamide (SAM) transported to the mesenteric venous blood and the serosal compartment were 19.7 and 45.8% of amount disappeared from the intestinal lumen, respectively and those of benzoic acid (BA) were 47.4 and 12.7%, respectively. The permeability of SAM into the serosal compartment was 2.8 times of that into the mesenteric venous blood, while the permeability of BA into the serosal compartment was only one fourth of that into the mesenteric venous blood.

Animals↗
PubMed1989

Effects of cimetidine on quinidine distribution and tissue pH in rats.

To elucidate the mechanism(s) of the decrease of the volume of distribution at steady state (Vdss) and the tissue-to-plasma concentration ratio (Kp) of quinidine after cimetidine treatment, the following were studied; (1) the effect of cimetidine on the tissue binding of quinidine in vitro, (2) the non-linear tissue distribution of quinidine and (3) the effect of cimetidine on tissue pH. The in vitro binding of quinidine to rat tissue homogenates was not affected by cimetidine treatment. The tissue distribution of quinidine in rats was linear from 1 to 5 micrograms/ml of plasma concentration except for lung. The plasma disappearance of 5,5-dimethyl-2,4-oxazolidinedione (DMO) after a 200 mg/kg intravenous injection was fitted to a two compartment open model. In the cimetidine-treated rats (50 mg/kg), the pharmacokinetic parameters of DMO, such as the plasma total body clearance (Cltot), Vdss and the rate constant at the terminal phase (beta) increased to 230, 110 and 210% of those of the non-treated rats, respectively. The intracellular pH calculated by Kp of DMO increased significantly in liver, spleen, intestine, brain, muscle and skin. This suggests that cimetidine decreased the tissue-to-plasma pH partition coefficient (q) of unbound quinidine in several tissues. The decreases of Vdss and Kp of quinidine by cimetidine was attributed to the decrease of q resulting from the increase of tissue pH.

Acid-Base Equilibrium↗
PubMed1989

The inhibitory effects of cimetidine on elimination and distribution of propranolol in rats.

We studied the effects of cimetidine on the pharmacokinetics, blood and tissue distribution and plasma protein binding of propranolol in rats. The plasma disappearance of propranolol after a 10 mg/kg intravenous injection and oral administration were fitted to a two compartment open model. In the cimetidine treated rats, the area under concentration curve after an intravenous injection (AUCiv) was increased by 64% and the plasma total body clearance (Cltot) and the rate constant at the terminal phase (beta) were decreased by 38% and 33% of those of the non-treated rats, respectively. The area under the concentration curve after oral administration (AUCpo) was increased by 62% and the plasma oral clearance (Clpo) was decreased by 39% by cimetidine treatment, whereas the bioavailability (F) was not changed. The hepatic blood flow rate (Qh) and the product of the plasma unbound fraction and the hepatic intrinsic clearance (fp x Clint,h) calculated from Cltot and Clpo were decreased by 30% and 39%, respectively. The blood-to-plasma concentration ratio (Rb) and the tissue-to-plasma concentration ratio (Kp) of propranolol were not affected by cimetidine treatment, while the binding constant (Kb) in plasma was decreased by 45%. The plasma unbound fractions (fp) of propranolol were increased by 25-70% in the in vivo plasma concentration range (0.1-1.0 microgram/ml) resulting in the decrease of tissue-to-plasma unbound concentration ratio (Kp,u) in lung, heart, spleen, brain and muscle. Cimetidine was shown to have the inhibitory effects on elimination and distribution of propranolol in rats.

Administration, Oral↗
PubMed1988

Effects of cimetidine on lidocaine distribution in rats.

The effects of cimetidine on the disappearance from plasma, plasma protein binding, tissue distribution, tissue binding in vitro and uptake by erythrocytes of lidocaine were studied in rats. The plasma disappearance of lidocaine after a 10 mg/kg bolus injection was analyzed by a two-compartment open model. In the cimetidine-treated rats (50 mg/kg bolus injection, the plasma total body clearance (Cltot), the volume of distribution at the steady state (Vdss) and the elimination rate constant of the central compartment (kel) of lidocaine decreased by 27, 28 and 32% of those of the non-treated rats, respectively. The plasma concentration of lidocaine at the steady state, after a loading dose (7.62 mg/kg body weight) followed by an infusion (0.16 mg/min/kg), increased from 1.62 to 2.69 micrograms/ml after cimetidine treatment. The tissue-to-plasma concentration ratio (Kp) in spleen, stomach and skin decreased to 64, 62 and 62% of the values of the non-treated rats. In addition, the blood-to-plasma concentration ratio (Rb) decreased by 26% in cimetidine-treated rats. In vitro tissue-to-plasma concentration ratios (Kp, vitro) of lidocaine in spleen, stomach and skin homogenate were decreased to 58, 45 and 68% by cimetidine treatment. In these tissues, the percentage decreases of Kp, vitro agreed with those of Kp determined in vivo. The decrease of Kp by cimetidine treatment may be due to the inhibition of tissue binding of lidocaine. The uptake of lidocaine by erythrocytes was decreased by cimetidine treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Effects of cimetidine on quinidine distribution in rats.

The effects of cimetidine on the time course of plasma concentration, plasma protein binding and tissue distribution of quinidine were studied in rats. The plasma disappearance of quinidine after a 25 mg/kg intravenous injection was fitted to a two compartment open model. In the cimetidine-treated rats (50 mg/kg), the pharmacokinetic parameters of quinidine, such as the plasma total body clearance (Cltot), the volume of distribution at steady state (Vdss) and the elimination rate constant of the central compartment (kel) decreased to 62, 60 and 73%, respectively of those of the non-treated rats. The plasma concentration of quinidine at steady state, after an intravenous injection (20 mg/kg body weight) followed by a constant rate infusion (0.2 mg/min/kg), increased from 3.02 to 5.11 micrograms/ml after cimetidine treatment. The tissue-to-plasma concentration ratio (Kp) of heart, brain and muscle, determined in homogenates at steady state, decreased after cimetidine treatment. The effect of cimetidine lasted several hours after a cimetidine bolus intravenous injection. These decreases of Kp could satisfy quantitatively the decrease of Vdss. It may be concluded that the decrease of Vdss was due to the inhibition of tissue distribution (binding and/or partition to tissue components) of quinidine by cimetidine treatment.

Animals↗
PubMed1987

A freeze-fracture study of the plasma membrane of the Ito cell in the normal rat liver.

The plasma membrane of the Ito cell in the normal rat liver was studied by freeze-fracture electron microscopy. Ito cells appeared to adhere to endothelial cells or to be embedded in the microvilli of hepatocytes. Ramified processes with a few microvilli of the cell extended along the endothelial cells. Caveolae were constantly seen on the plasma membrane, but their numbers varied among cells. Two different patterns of intramembranous particles were found on the plasma membrane of the Ito cells: most cells showed an even distribution of the particles, but the others, aggregates of them. Particle-free domains were seen on the plasma membrane in some Ito cells. Piles of concave or convex sheets were sometimes seen in the freeze-fractured lipid droplets.

Animals↗
PubMed1985

Intestinal absorption of salicylamide and effect of atropine on it.

The effect of atropine (ATR), a parasynpatholytic agent, on the intestinal absorption of salicylamide (SAM) was studied using the absorption kinetic model proposed by Winne et al. The disappearance of SAM from perfusate and the appearance in intestinal blood were determined using perfused intestinal loop of the rat in vivo. The results showed that the absorption of SAM was simulated by the four compartment model consisting of luminal, interstitial, blood and serosal compartments. The model was assumed to have three rate determining factors, namely mucosal membrane permeability, clearance by blood flow and serosal membrane permeability. ATR decreased the absorption of SAM by decreasing the clearance factor relating to intestinal blood flow and increased the fraction of the transported amount of SAM from interstitial space to serosal compartment.

Animals↗
PubMed1984

A freeze-fracture study on the basolateral plasma membrane of the gastric parietal cells in fasting and refed rats.

The basolateral plasma membrane of the gastric parietal cells in rats after food-deprivation and food-restitution was studied by thin-section and freeze-fracture electron microscopy. A decrease in the number of tubulovesicles and dilatation of the canalicular lumen were generally observed in the parietal cells of the refed rats. Basal folds, demonstrated both in fasting and food-resupplied rat groups parietal cells by thin-section electron microscopy, appears as branched furrows on the P face and branched wrinkles on the E face plasma membrane by the freeze-fracture replica method. Parietal cells providing numerous basal folds appeared to be more numerous in refed rat gastric gland. The basal folds may represent, at least to some extent, a reservoir of a surplus plasma membrane and play an important role in secreting substances into and also absorbing substances from the blood capillary via the underlying connective tissue.

Animals↗
PubMed1982

Further electron-microscope studies on the human hepatic sinusoidal wall with special reference to the fat-storing cell.

In biopsy specimens from two normal human livers, fat-storing cells and Kupffer cells were observed by electron microscopy with the following results: 1) In the human Ito cells numerous micropinocytotic caveolae and vesicles occurred either scattered beneath the plasma membrane or fused into short tubules. In the cytoplasm abutting on these structures, minute clusters of glycogen beta-particles were revealed which presumably had been synthesized in the local cytoplasm from carbohydrate (glucose) ingested by pinocytosis. 2) Lipid droplets (vacuoles) were formed within the accumulations of the glycogen beta-particles. These findings support the view that the glycogen synthesized in the Ito cells may represent a transitional compound in the process of lipid synthesis from carbohydrate. 3) Among lipid vacuoles, electron-dense droplets equally large were found, often containing electron-lucent areas in their center. On the surface of these dense droplets, compact clusters of glycogen particles adhered as if they might have permeated into the droplets. These droplets may possibly be immature lipid droplets retaining chemical properties of the glycogen in their superficial part; they remained insoluble during the preparation procedures for ultrathin sections. 4) The occurrence of the worm-like structure has for the first time been revealed in the human Kupffer cells. Besides its short tubular profiles, a more complex structure was demonstrated.

Female↗
PubMed1981

Freeze-fracture study on the whorls of rough endoplasmic reticulum in the exocrine pancreatic cells of the Japanese newt and African clawed toad.

The whorls of rough endoplasmic reticulum (rER) in the exocrine pancreatic cells of starved newts and clawed toads were examined by a freeze-fracture technique. The whorl appeared to be roughly ovoidal in shape and composed of tightly packed, narrow cisternae arranged like the layers of an onion. The clusters of interdigitating projections of the cisternal membranes were located at several places on the whorl. Some of these projections extended to the vesicular rER around the whorl. The fenestra-like, raised or hollowed craters were seldom seen on the fractured membrane faces of the whorls in the exocrine pancreatic cells of the starved newts.

Animals↗