PubMed Health⌕ Search

Biomedical subjects

S Obara

Publications and source records attributed to S Obara.

At least 37 records · Page 2Linked to original sources
PubMed1997

Pharmacological properties of traditional medicines. XXIII. Searching for active compounds in the blood and bile of rats after oral administrations of extracts of sansohnin [symbol: see text].

We made a trial of searching for the bioactive substances from Sansohnin [symbol: see text]. The blood and bile of rats after the oral administration of extracts of Sansohnin were analyzed by three-dimensional high-performance liquid chromatography (3D-HPLC). In blood, spinosin and feruloyl spinosin were found after the oral administration of a butanol extract of Sansohnin. In bile, spinosin and feruloyl spinosin were also identified after the oral administration of a water extract of Sansohnin. Spinosin and feruloyl spinosin induced the prolongation of hexobarbital sleeping time in mice at doses of 50 and 100 mg/kg, respectively. We concluded that spinosin and feruloyl spinosin were the bioactive constituents of Sansohnin. It was assumed that spinosin and feruloyl spinosin circulated through the intestine and liver, therefore, these results will provide support for the sedative and hypnotic use of this crude drug in Oriental medicine.

Administration, Oral↗
PubMed1997

Development of cellulose derivatives as novel enteric coating agents soluble at pH 3.5-4.5 and higher.

Hydroxypropyl methylcellulose (HPMC) was selected as a base polymer to develop novel enteric coating agents for acid protection which can dissolve at pH around 4, and was modified with trimellitic acid or maleic acid at various degrees of substitution. These carboxylic acids have higher dissociation constants and higher solubility in water than the carboxylic acids of existing enteric coating polymers. The synthesized polymers were micronized and dispersed in aqueous medium to determine their pKa values by potentiometric titration. The pH of dissolution and the water vapor permeability of the cast films prepared from organic solutions were also evaluated. Hydroxypropyl methylcellulose trimellitate (HPMCT) showed good acid resistance, and the pH at which it dissolves can be controlled in the range of pH 3.5 to 4.5 by varying the content of trimellityl groups and the methoxyl substitution of the base polymer.

Cellulose↗
PubMed1997

A repeated-dose dermal toxicity study of hydrophobically modified hydroxypropyl methylcellulose in rats.

A six-month repeated-dose dermal toxicity study followed by a 30-day recovery test of hydrophobically modified hydroxypropyl methylcellulose (HM-HPMC), a new cellulose derivative used as a thickener for topical pharmaceuticals, was conducted using rats. Aqueous paste of HM-HPMC was applied to the skin of rats once daily at dose levels up to 60 mg/kg/day, which was the highest dose that could be administered. Items checked included general signs, urinalysis, hematology, ophthalmology, and histopathology. One rat died during the administration period owing to a malignant tumor in the hemopoietic system, which was not attributed to the test substance. Statistically significant differences were found in some test results, but those were not dose-dependent and were considered to be incidental or spontaneous. It was concluded that the test substance was not toxic upon chronic dermal administration at dose levels up to 60 mg/kg/day.

Administration, Cutaneous↗
PubMed1995

Full-thickness skin grafting of postsurgical oral defects: short- and long-term outcomes.

PURPOSE: This study evaluated the use of full-thickness skin grafts (FTSGs) following excision of precancerous and cancerous oral lesions. MATERIALS AND METHODS: Fourteen oral lesions, including five leukoplakias, one carcinoma in situ, two verrucous carcinomas, and six squamous cell carcinomas with varying grade of keratinization and invasion were skin grafted after excision. The size of the graft ranged from 16 x 22 mm to 40 x 50 mm, and the fixation period was 8 to 13 days. The grafts were evaluated for necrosis as a short-term result and shrinkage and recurrence of the lesion as long-term results. RESULTS: Three cases with more than moderate necrosis of the grafted skin were observed (21.4%). Shrinkage was observed in 23% of the 14 skin grafts and tumor recurrence was observed in three FTSGs (2 patients). CONCLUSIONS: The results suggest that the paucity of the blood supply in the grafted bed, and the uneven pressure and immobilization of the grafted skin, influence the success of the procedure, and that proper case selection is necessary.

Aged↗
PubMed1995

A comparison of three methods used for treatment of ranula.

PURPOSE: This report compares the treatment results for oral and plunging ranulas. PATIENTS AND METHODS: Twenty-seven patients were retrospectively examined concerning treatment methods and recurrence on the basis of their medical records. The surgical specimens were also examined microscopically. RESULTS: Four patients had excision of the ranula only, 22 had marsupialization, and nine had removal of the sublingual gland combined with the excision of the ranula. These treatments showed a 25.0%, 36.4% and 0% recurrence rate, respectively. Histological observation revealed no epithelial lining in any of the examined specimens. CONCLUSIONS: Removal of the sublingual gland combined with the ranula was the most reliable method among the above three used.

Humans↗
PubMed1995

Thermal responses to swimming in three water temperatures: influence of a wet suit.

The primary objective of this investigation was to determine the thermal and metabolic effects of wearing a rubberized wet suit (WS) while swimming for 30 min in 20.1, 22.7, and 25.6 degrees C water. Metabolic and body temperature measurements were recorded in each water temperature with subjects wearing either a WS or a competitive swimming suit (SS). Immediately after each swim the subjects cycled for 15 min on a stationary cycle ergometer. Energy expenditure (VO2), heart rate, post-swim blood lactate, work completed on the cycle ergometer, and rating of perceived exertion (RPE) were similar in all trials. Mean (+/- SE) core temperature (Tc) during swimming in the SS trials increased 0.56 (+/- 0.33), 0.48 (+/- 0.20), and 1.22 (+/- 0.24) degrees C, whereas in the WS trial Tc rose 0.62 (+/- 0.22), 1.02 (+/- 0.15), and 0.89 (+/- 0.13) degrees C in the 20.1, 22.7, and 25.6 degrees C treatments, respectively. Following swimming many of the subjects experienced a decrease in Tc, but it was significantly elevated above preimmersion by the end of cycling in all trials except the SS 20.1 degrees C trial. Mean trunk temperatures (Ttr) during swimming in the WS trials were 4.32 +/- 0.16 (20.1 degrees C), 3.90 +/- 0.25 (22.7 degrees C), and 3.21 +/- 0.20 (25.6 degrees C) degrees C warmer than in the SS. Ttr rose after the subjects exited the water, but remained significantly below baseline throughout cycling in all trials.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Properties of free films prepared from aqueous polymers by a spraying technique.

A spray method for the preparation of free films from aqueous polymeric dispersions was investigated. Free films were prepared from aqueous dispersions of methacrylic acid-ethyl methacrylate copolymer (Eudragit L 30D), hydroxypropyl methylcellulose acetate succinate (HPMCAS), cellulose acetate phthalate (CAP), and ethyl cellulose (EC) by a spray method and a cast method, and their mechanical properties and reproducibility were investigated. Uniform films were obtained from the dispersions of Eudragit L 30D, HPMCAS, and EC by the spray method, but films could not be formed by spraying the CAP dispersion. The tensile strength, elongation, and elastic modulus of the sprayed Eudragit L 30D films were similar to the properties of the cast films, and good reproducibility was obtained from both methods. Marked within-run variation in the mechanical properties was observed for the cast HPMCAS and CAP films, which could be due to a settling of the solid particles during the drying step. The variation in the mechanical properties of the sprayed HPMCAS films was lower and the tensile strength significantly higher than that of the cast films. There were also significant differences in tensile strength and elongation of EC films between products of the two methods. The results indicated that the spray method used to prepare the free films from aqueous polymeric dispersions provided uniform films with consistent and reproducible properties.

Acrylic Resins↗
PubMed1993

Chloride current observed as calcium-gated tail current in trigeminal root ganglion neurons of the marine catfish, Plotosus.

Isolated trigeminal ganglion (TRG) neurons of Plotosus in primary culture were studied with patch electrodes in a whole-cell recording configuration. When Ca currents were isolated using electrodes filled with CsCl and Ca buffer in Na- and K-free saline, a large tail current was induced. Both Ca and tail currents were blocked by 2 mM Co2+ in the bath. Reversal potential of the tail current was close to the equilibrium potential for Cl-. The reversal potential was altered by substitution of external Cl- with Br- or methanesulphonate- (MSA-). The anion permeability ratios were estimated as PBr/PCl = 1.95 and PMSA/PCl < 0.05. These results suggested that the tail current was the Ca-gated Cl current. In Plotosus neurons, two types of Ca current, high- and low-voltage activated (HVA and LVA), have been described. Both types of Ca currents were able to induce a tail current. Ba currents through both HVA and LVA channels proved to be ineffective. Upon repetitive activation, the tail current progressively increased in the presence of a nearly constant peak Ca current, and showed a more prolonged complex decay phase. When the electrode was filled with 20 mM EGTA, no tail current was induced, not even after repetitive stimulation. Therefore, the tail current seemed to be regulated by local Ca activity in the vicinity of the membrane. The Ca-gated Cl tail current may regulate the membrane excitability of TRG neurons during repetitive firing.

Animals↗
PubMed1993

Changes in cardiac rhythm in man during underwater submersion and swimming studied by ECG telemetry.

A previously reported method for electrocardiographic (ECG) telemetry in water using frequency-modulated current was improved to obtain more stable ECGs. The ECGs of seven healthy men were monitored using the improved method during and after whole-body submersion or underwater swimming. Bradycardia and arrhythmias were observed during the submersion, and transient tachycardia was detected after the start of underwater swimming, followed by bradycardia with arrhythmias. Three different types of arrhythmias were observed: sinus arrhythmia (SA), supraventricular extrasystole (SE) and ventricular extrasystole (VE). SA and SE tended to develop during the latter half of the period of submersion or underwater swimming, and especially after the restart of breathing. VEs were detected in only one subject during submersion, whereas they occurred in most subjects during and after underwater swimming. Individual variations were found in development of arrhythmias, one subject showing no arrhythmia. Bradycardia, SA and SE could depend on vagal suppression in underwater conditions, and VE may be related to the effect of muscular movement on cardiac function in addition to vagal inhibition.

Adult↗
PubMed1993

Superoxide anion generation from peripheral blood neutrophils stimulated by N-formyl-methionyl-leucyl-phenylalanine in oromaxillary cancer patients.

Superoxide anion (O2-) generation levels in peripheral blood neutrophils stimulated by N-formyl-methionyl-leucyl-phenylalanine were evaluated in patients with oromaxillary cancer. The levels in patients with benign tumors were nearly equal to those of normal controls. Patients with squamous cell carcinoma in stage I and II had levels that were widely distributed. On the other hand, O2- generation levels in the advanced stages (III and IV) of squamous cell carcinoma showed lower levels than those of controls (P < .01). All cases of oromaxillary carcinoma showed low levels of O2- generation within 1 month before death compared with controls (P < .01). The generation levels of O2- in the posttreatment period were lower than those before combination cancer treatments. Among cancer treatments such as chemotherapy, surgery, and irradiation, the latter had the strongest effects on O2- generation. These results suggest that low levels of O2- generation by peripheral blood neutrophils may reflect a worsening status of oromaxillary cancer patients.

Adenocarcinoma↗
PubMed1992

The membrane properties and Ca-currents of the trigeminal root ganglion cells in primary culture of the marine catfish, Plotosus, studied with whole-cell recordings.

Neurons of the trigeminal root ganglion (TRG) were isolated from the marine catfish Plotosus. Collagenase treatment and culture in L15 medium, modified for higher tonicity, were required to remove their myelin sheath. TRG neurons were spherical 15-20 microns in diameter after 1-4 days culture, although they later developed extensive neurites. The membrane properties were studied by whole-cell recording technique. The resting potential was about -63 mV. The specific membrane resistance and capacitance, 5.9 K omega.cm2 and 1.2 microF/cm2, were similar to those of mouse dorsal root ganglion (DRG). The action potential, however, was usually humped, and followed by a long afterhyperpolarization. The maximum firing rate reached only about 70 Hz. Voltage-clamp study revealed TTX-sensitive Na current and TEA-sensitive K current, and in addition, two types of Ca currents: low- and high-voltage activated (LVA and HVA). The HVA current seemed to be involved in hump formation. The LVA current was similar in kinetics to T-type current of chick DRG, and was presumably inactivated at the resting potential, which might be removed during the afterhyperpolarization.

Action Potentials↗
PubMed1992

Induction of propranolol metabolism by the azo dye sudan III in rats.

Effects of the azo dye sudan III, an inducer of cytochrome P450 isozymes belonging to the CYP1A subfamily, on propranolol (PL) in vitro and in vivo metabolism were investigated in rats. The kinetic parameters of the activity for each metabolic pathway were determined in liver microsomes from control and sudan III-treated rats. Sudan III pretreatment increased extensively PL 4-hydroxylase, 5-hydroxylase and N-desisopropylase activities at high but not at low PL concentrations. On the other hand, kinetic parameters of 7-hydroxylase activity were not affected by sudan III pretreatment. Sudan III pretreatment decreased blood concentrations of PL after intraportal infusion of PL at high doses (12.5 and 20 mg/kg), but not at a low dose (5 mg/kg). These observations were consistent with data obtained from the in intro studies showing that sudan III pretreatment induced low-affinity but not high-affinity cytochrome P450 isozymes involved in PL metabolism in rat liver microsomes.

Animals↗
PubMed1992

Changes in the concentrations of Na+, K+ and Cl- in secretion from the skin during progressive increase in exercise intensity.

A simple method for sampling skin secretion in 1-min periods was developed for investigating the effects of progressive increases in exercise intensity on Na+, K+ and Cl- secretions from the skin of the forearm. Ten healthy male subjects performed exercise consisting of eight stepwise increases in intensity from 50 to 225 W, with a 25-W increase at each step. Exercise at each step was for 3 min followed by a 1-min recovery period. Samples of blood and skin secretion were taken during the recovery period. Significant positive correlations were found between the mean concentrations of Na+ and Cl- and between those of K+ and Cl- in the skin secretion. The concentrations of electrolytes in the skin secretion also showed significant correlations with the blood lactate concentrations. The inflection points for secretions of Na+, K+ and Cl- were 4.04, 3.61 and 3.83 mmol.l-1 of blood lactate; 64.42, 61.96 and 62.14% of maximal oxygen consumption (VO2max); and exercise intensities of 123.01, 117.65 and 125.07 W, respectively. No significant differences were observed between the value of 67.27% of VO2max or 134.00W at the onset of blood lactate accumulation (OBLA) and the inflection points. From these results we concluded that changes in electrolyte concentrations in skin secretion during incremental exercise according to this protocol were closely related with the change in the blood lactate concentration, and that the inflection points for electrolytes may have been near the exercise intensity at OBLA.

Adult↗
PubMed1992

Studies on single-dose toxicity of hydrophobically modified hydroxypropyl methylcellulose in rats.

Single-dose toxicological studies of hydrophobically modified hydroxypropyl methylcellulose (HM-HPMC, hydroxypropyl methylcellulose modified with stearylglycidylether) were conducted. A dispersion of HM-HPMC was administered to rats orally or by dermal application at doses up to 900 mg/kg. After the oral administration, the mean body weight of the 900 mg/kg group on the first day after administration was slightly but significantly lower (P less than 0.05) than that of the control group, and one rat had loose stools at 30 min. after the administration. No other abnormalities were noted. In the case of dermal application, no abnormalities were observed. No rats died, and no abnormalities in their organs were found by either route. In conclusion, there was no observed toxicity of HM-HMPC after oral or dermal administration at single dose up to 900 mg/kg under the conditions of these studies.

Administration, Cutaneous↗
PubMed1992

Primary dermal and eye irritability tests of hydrophobically modified hydroxypropyl methylcellulose in rabbits.

Primary dermal and eye irritation tests of hydrophobically modified hydroxypropyl methylcellulose (HM-HPMC, hydroxypropyl methylcellulose modified with stearylglycidylether), a new cellulose derivative used as a thickener for topical pharmaceuticals and cosmetics, were conducted in rabbits. A dispersion of HM-HPMC (3%) was applied to intact and abraded skins and reactions were observed. A very slight erythema was observed in both skins and this polymer was categorized as a "mild irritant". In the eye irritation test, with a dispersion of the same concentration, it was categorized as "marginal" in unrinsed eyes and "negative" in rinsed eyes.

Administration, Cutaneous↗
PubMed1991

Evidence for the endogenous GTP-dependent ADP-ribosylation of the alpha-subunit of the stimulatory guanyl-nucleotide-binding protein concomitant with an increase in basal adenylyl cyclase activity in chicken spleen cell membrane.

We investigated the endogenous GTP-dependent ADP-ribosylation of the alpha-subunit of the stimulatory guanyl-nucleotide-binding protein (Gs alpha) concomitant with an increase of basal adenylyl cyclase activity in chicken spleen cell membranes. When these membranes were incubated with [adenylate-32P]NAD, there was significant incorporation of [32P]ADP-ribose into a 45-kDa acceptor protein in the membranes. This reaction was inhibited when 20 mM arginine was present during the incubation. When the membranes were incubated with unlabelled NAD, subsequent ADP ribosylation by cholera toxin was diminished significantly. Thus, chicken spleen cell membranes have the potential to endogenously ADP-ribosylate the arginine residue of Gs alpha. The endogenous ADP-ribosylation Gs alpha was enhanced by the addition of 0.1 mM GTP or 0.1 mM guanosine 5'-[gamma-thio]triphosphate (GTP[S]), but not 0.1 mM GDP, 0.1 mM ATP or 0.1 mM ADP. The endogenous GTP-dependent ADP-ribosylation of Gs alpha stimulated basal adenylyl cyclase activity. Furthermore, NAD-induced stimulation of basal adenylyl cyclase activity was suppressed, when the membranes were incubated with NAD in the presence of novobiocin, an inhibitor of arginine-specific ADP-ribosyltransferase. These data represent the first demonstration that a eukaryotic cell membrane contains an ADP-ribosyltransferase which can catalyze the endogenous GTP-dependent ADP-ribosylation of the arginine residue of Gs alpha and that this modification enhances basal adenylyl cyclase activity in the membrane. In light of this evidence, the possible control of basal adenylyl cyclase activity via endogenous GTP-dependent ADP-ribosylation in eukaryotic cells warrants further attention.

Adenosine Diphosphate Ribose↗