PubMed Health⌕ Search

Biomedical subjects

S Kasai

Publications and source records attributed to S Kasai.

At least 163 records · Page 9Linked to original sources
PubMed1990

Effects of chelated sera and alteration in calcium concentration on the growth of oral epithelial cells in primary culture.

The purpose of this study were to examine the distribution of growth-promoting activity of some chelated sera and to investigate the relationship between calcium concentration in culture medium and the growth-promoting activity of the chelated sera in comparison with that of the original serum. Results showed that the chelated serum obtained by acidic resin treatment promoted colony formation, while the number of colonies decreased in cultures containing either dialyzed serum or chelated one obtained by treatment with alkaline resin. The acid-chelated serum and its lyophilized materials maintained the growth-promoting activity for 6 months or more in a deep freezer. This activity depended on the calcium concentration of culture medium in the range from 0.06 to approximately 1.5 mM. The optimal concentration of this material for growth promotion was 4 mg/ml as the protein density, which was about a quarter of that for the original serum protein. Sera from different sources treated with the acidic resin also showed similar effect on the growth. This finding strongly suggests that the acid-chelated serum and its lyophilized protein contain a keratinocyte growth factor(s).

Animals↗
PubMed1990

[Optimal calcium concentration for the proliferation of oral mucosal epithelial cells from adult rabbit in vitro].

We studied a primary culture of oral epithelial cells from adult rabbit and reported about dose-dependent growth by Ca increase. Therefore, in the present study we examined the relationship between total Ca, or Ca ion concentration and the proliferation of oral epithelial cells. The results were as followings. 1. The optimal Ca concentration for the growth in primary culture of oral epithelial cells was affected by the serum concentration in the medium. But Ca ion concentration for the best growth was in 10-30 micrograms/ml (0.25-0.74 mM) regardless of the serum concentration. 2. The optimal Ca ion concentration was shifted to 3-20 micrograms/ml (0.075-0.5 mM) in the medium containing chelated serum. This fact, suggests that the chelated serum may play different action from whole serum. 3. The optimal Ca ion concentration in the present study was higher density region than Hennings's view (0.04-0.1 mM) and it was lower than that of Tong (1.4-2.8 mM). Our data coincided with that of Wille (0.18-0.36 mM) who used MCDB 153 medium.

Animals↗
PubMed1990

[Protective effects of DBcAMP on ischemic liver failure in dogs].

We studied protective effects of Dibutyryl cyclic AMP (DBcAMP) which is a permeable form of cyclic AMP on ischemic liver failure (ischemic time: 90 minutes). Mongrel dogs were used. A portal-systemic bypass was established by inserting a heparinized catheter between the splenic vein and the femoral vein. Acute liver failure was induced by the en bloc clamp of the porta hepatis. In the treated group, 0.1 mg/kg/min (total dose, 300 mg) of DBcAMP was injected intravenously from three hours before the clamp to the end of the experiment. The control group was injected physiological saline. Effects of DBcAMP were evaluated according to survival rates, blood pressure, serum biochemical findings, hepatic blood flow, ATP levels in liver tissues and histological findings. The survival rates were 16% in the control group, and 88% in the treated group. The mean blood pressure after reperfusion was rapidly decreased in the control group while in the treated group, it was maintained nearly 100 mmHg. Serum biochemical findings, hepatic blood flow and tissue ATP levels were significantly improved in the treated group. On histological findings, necrosis with bleeding was observed one day after ischemia in the control group while in the treated group mild chronic ischemic change without necrosis was observed on two weeks after ischemia. In conclusion, ischemic liver failure was apparently protected by the administration of DBcAMP.

Adenosine Triphosphate↗
PubMed1989

Comparison of jaw-opening reflex response elicited by anterior and posterior tooth tapping in the cat.

The response elicited by various levels of controlled mechanical stimuli to maxillary teeth was studied in 8 adult cats anaesthetized with alpha-chloralose. When an anterior tooth was tapped, short (4-6 ms) and long (16-20 ms) latency responses were recorded from the mylohyoid nerve. On the other hand, when a posterior tooth was tap-stimulated, only the long-latency response was induced. The effects of ether narcosis on the responses were studied. As the short-latency response was induced only by anterior tooth tapping and its amplitude increased according to increases in stimulus intensity, the response may be related to the protection of the mouth from entrance of harmful materials. The long-latency response was induced by light tapping on both anterior and posterior teeth and its amplitude increased according to increases in stimulus intensity to the posterior teeth rather than the anterior teeth. As it was readily inhibited by ether, the long-latency response may have a reflex centre in an area like the brain stem reticular formation which is particularly sensitive to ether and may be related to the regulation of jaw movement in mastication.

Action Potentials↗
PubMed1989

[A computer program that draws pedigree charts for inbred strains of animals].

We produced a computer program that draws pedigree charts for inbred strains of animals such as mice or rats. This program is composed of four subprograms, which are (1) inputting the data, (2) drawing pedigree charts, (3) listing the data which have been input, and (4) backup of the system and the data. Pedigree charts and lists of data can be displayed on a TV screen and printed out on the papers. Using this program, we drew the pedigree charts of the inbred strains of rats which we are maintaining by brother-sister inbreeding in our institute and found that there were three sublines in one of the strains, WKAH/Hkm, because of unsuitable maintenance. This program is very convenient to draw the pedigree charts and useful for checking the maintenance of inbred strains or the strains of animal models of human diseases.

Animals↗
PubMed1989

Calcium action potential and prolonged afterhyperpolarization in developing myotubes of a mouse clonal myogenic cell line.

Under a high-Ca condition (greater than 5 mM), myotubes of a mouse myogenic cell line MC3T3-A1/M13 generated a long-lasting Ca action potential and a prolonged afterhyperpolarization (a.h.p.) during their in vitro development. The action potential was sensitive to Co or verapamil. Under a voltage-clamp condition, membrane depolarization more positive than -20 mV evoked a Ca-dependent inward current, which was apparently prolonged and responsible for the generation of the long-lasting action potential. The appearance of the Ca action potential preceded that of a Na spike by about 24 h, and it developed so that the maximum rate of rise became 26 +/- 4 V/s by day 7. Then this Ca-dependent potential faded as the myotubes matured, until the action potentials became solely Na-dependent. The a.h.p. was evoked accompanying the Ca action potential and was inhibited by quinine or quinidine, showing that it is operated by Ca-activated K channels. This channel developed together with the Ca channel and continued to exist during the myotube maturation process. These results indicate that the MC3T3-A1/M13 myotube at the initial stage of development has a highly developed Ca spike system that is due mostly to a high-threshold-type Ca channel.

Action Potentials↗
PubMed1989

A voltage-dependent calcium current in mouse MC3T3-E1 osteogenic cells.

MC3T3-E1 osteogenic cells in a growing state were voltage-clamped by the whole-cell patch-clamp method. The MC3T3-E1 cells exhibited a transient, fast-inactivating Ca inward current upon depolarizing pulses from a holding potential of -80 mV. This current had a threshold of activation of about -50 mV and was insensitive to the dihydropyridine, nifedipine. These results show that MC3T3-E1 cells have a voltage-dependent Ca channel corresponding to the "T-type."

Animals↗
PubMed1989

[Effect of activation of the reticuloendothelial system on hepatocyte regeneration in partially hepatectomized rats].

Enhanced effect on rat hepatocyte regeneration through activation of the reticuloendothelial system (RES) was investigated. RES was activated using by OK-432 and the phagocytic activity (K-value) increased 2-fold over control rats 24 hours after intraperitoneal injection of OK-432. In OK-432 treated rats, the amount of cyclic AMP in the regenerating liver also increased 1.5-fold higher than in control rats 14 hours after hepatectomy. After 70% partial hepatectomy, liver DNA synthesis in OK-432 treated rats increased 2 to 5-fold higher than in control rats. There was a good correlation between the K-value before hepatectomy and DNA synthesis 24 hours after hepatectomy (r = 0.96). Therefore the RES is one of the most important regulatory factors in liver regeneration. Augmentation of RES before hepatectomy may prevent hepatic failure after resection in liver diseases.

Animals↗
PubMed1989

[Protective effects of DBcAMP on acute liver failure induced by D-galactosamine in rats].

We studied protective effects of Dibutyryl cyclic AMP (DBcAMP) which is a permeable form of cyclic AMP (cAMP), the intracellular second messenger, on D-galactosamine (D-Gal, 1.5g/kg i.p.) induced acute liver failure. Experimental animals were divided into four groups: Group I; DBcAMP was administered before (7.5mg/kg) and after (7.5mg/kg) D-Gal treatment, group II; only before (15mg/kg) D-Gal treatment, group III; only after (15mg/kg) D-Gal treatment, and group IV; no DBcAMP was administered. Effects of DBcAMP were evaluated according to survival rates, serum biochemical findings and hepaplastin test (HPT), ATP levels in liver tissues, hepatic blood flow, and histological findings. The survival rates after D-Gal treatment were 100% in group I, 90% in group II, 32% in group III and 10% in group IV. The serum biochemical findings, tissue ATP levels and hepatic blood flow were significantly improved in groups I and II compared with that in groups III and IV. The level of HPT in group I was the highest among the experimental groups. On histological findings, inflammatory changes were observed in group I and focal necrosis in group II while liver degeneration with massive necrosis was seen in groups III and IV. In conclusion, acute liver failure induced by D-Gal was apparently protected by the administration of DBcAMP.

Acute Disease↗
PubMed1989

[Jaw and perioral reflexes elicited by tooth tapping in the cat].

The reflex responses elicited by tapping the maxillary canine were studied in 12 adult cats anesthetized with alpha-chloralose. Short (4-8 msec) and long (14-22 msec) latency responses were recorded from both efferent nerves innervating a digastric muscle and an inferior portion of perioral muscles. These two responses were also observed from a single fiber teased from the efferent nerve as two successive groups of spike discharges. The long-latency responses from the digastric and the perioral muscle were both elicited by a light tooth tapping and disappeared at about the same time following infiltration of local anesthetic over the tap-stimulated tooth root or following inhalation of ether narcosis. The long-latency responses from the above muscles may be, therefore, elicited by the same sensory information of the periodontal afferent, and have a common reflex center.

Animals↗
PubMed1988

Conformational change in plasma albumin due to interaction with isolated rat hepatocyte.

The electron spin resonance spectroscopy of 4-isothiocyanato-tempo labeled to bovine serum albumin (BSA) and the absorption spectroscopy of eosin maleimide labeled to BSA in the isolated rat hepatocyte suspension indicate conformational change occurring in the albumin molecule during interaction with the hepatocellular membrane. The conformational change in the albumin molecule may possibly accelerate the dissociation of albumin-organic anion complexes at the surface of the liver cell. The conformational change in the albumin molecule may explain in part the mechanism of albumin-mediated hepatic transport.

Animals↗
PubMed1988

Intestinal absorption of riboflavin, studied by an in situ circulation system using radioactive analogues.

The intestinal absorption of riboflavin was studied using radioactive riboflavin and its analogues 8-demethylriboflavin, 3-methylriboflavin, 5'-deoxyriboflavin, 2'-deoxyriboflavin, 7,8-dimethyl-10-hydroxyethylisoalloxazine, lumiflavin, lumichrome, and riboflavin-5'-monosulfate, which were synthesized with high specific radioactivity. A specific absorption of riboflavin at dietary concentrations was confirmed using an in situ circulation system. The relation between the chemical structure of flavins and the absorption mechanism was studied using this system. The 8-demethylriboflavin, an analogue modified at benzene moiety of the isoalloxazine ring, was absorbed in a similar way to riboflavin, by dual kinetics: by a process specific for riboflavin at dietary concentrations and by simple diffusion (nonspecific absorption) predominating at higher concentrations (over 100 microM). However, 3-methylriboflavin and analogues modified at the ribityl group, including 5'-deoxyriboflavin, were absorbed only via simple diffusion even at dietary concentrations. Many flavins examined, except for 3-isobutylriboflavin, 3-carboxymethylriboflavin, lumichrome, and riboflavin-5'-monosulfate, interfered with the specific absorption of riboflavin. It was concluded from these results that one of the specific absorption processes for riboflavin is a phosphorylation-dephosphorylation process. Four water-soluble vitamins did not interfere with the specific absorption of riboflavin, indicating that these vitamins do not share a common specific absorption pathway with riboflavin.

Animals↗