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Biomedical subjects

A Takai

Publications and source records attributed to A Takai.

At least 73 records · Page 4Linked to original sources
PubMed1985

Effects of readmission of substrate on the membrane potential in glycogen-depleted guinea-pig taenia coli.

In the glycogen-depleted smooth muscle of the guinea-pig taenia coli, application of glucose or beta-hydroxybutyrate (beta-HB) in the presence of 20 mM-K or carbachol (5 microM) produced a transient hyperpolarization for about 1 min followed by a sustained depolarization accompanied by spike activity. The early hyperpolarization was highly temperature dependent, so that below 30 degrees C, substrate application produced the depolarization with a delay of approximately 2 min, without a clear preceding hyperpolarization. The responses to substrate were not affected by ouabain (10 microM). Readmission of K after a treatment with K-free solution for 10 min caused a transient hyperpolarization only in the presence of substrate. This hyperpolarization was abolished by ouabain. Verapamil (0.1 microM) blocked the substrate-induced depolarization, revealing an underlying slow hyperpolarization. Removal of Ca abolished both the hyperpolarization and depolarization caused by substrate application, but the hyperpolarization disappeared much more slowly than the depolarization. Removal of the external K had little effect on the substrate-induced hyperpolarization, but the hyperpolarization induced by substrate application was increased when the external K was increased up to approximately 20 mM. Both the hyperpolarization and the depolarization were not clearly affected by completely replacing Na with choline. The results suggest that ATP supplied by the addition of substrate activates some electrogenic pump, probably a Ca pump, causing hyperpolarization, and that ATP also removes the inactivation of Ca conductance with some delay, resulting in an increased depolarization.

3-Hydroxybutyric Acid↗
PubMed1985

Cephamycin inactivation due to enzymatic hydrolysis by beta-lactamase from Bacteroides fragilis.

The susceptibility of 53 clinical isolates of Bacteroides fragilis to cephamycins was examined. Judging from the MICs for 50% of the strains tested, moxalactam was the most active, however, judging from the MICs for 90% of the strains tested, cefbuperazone was more effective than moxalactam. A correlation was observed between in vitro activity of benzylpenicillin and cephaloridine and beta-lactamase production. Inactivation due to enzymatic hydrolysis of cephamycins over a short time was not observed; however, inactivation was detected by a double disk diffusion test, and moxalactam was most easily inactivated. We conclude that inactivation due to enzymatic hydrolysis of cephamycins over a long time may play an important role in resistance to some cephamycins in strains of B. fragilis.

Bacteroides fragilis↗
PubMed1985

Contraction of smooth muscle in Ca-free solution.

The tonic contractions which are extremely resistant to removal of the external Ca were investigated in the rat vas deferens and myometrium. Both the noradrenaline response in the vas deferens and the oxytocin response in the myometrium could be repeatedly produced without appreciable diminution in Ca-free solution for more than 24 hrs. On the other hand, the tissue Ca content decreased exponentially after Ca-removal with a half time of 130-180 min. When Ca was readmitted, no indication of the early transient contraction was observed in the subsequent response in Ca-free solution, but the response was reduced compared with the response before Ca readmission. Verapamil suppressed the response in the presence of Ca, while it had very weak inhibitory effect even at 10 microM. Calmodulin antagonists of phenothiazine derivatives had a strong inhibitory effect on Ca-induced contractions, whereas they had very weak effects on the receptor-mediated contraction in Ca-free solution. Another calmodulin antagonist, W-7 suppressed both Ca-induced contraction and the contractions independent of external Ca. HA-1004, a vasodilator which has a structure similar to W-7, reduced the receptor-mediated contraction in Ca-free solution without much effect on Ca-induced contractions. These results may suggest that the receptor-mediated contractions resistant to Ca-removal are caused by some process without a contribution of the Ca-calmodulin system.

Animals↗
PubMed1985

Light and electron microscopic studies of perineural invasion by esophageal carcinoma.

Light and electron microscopic findings on perineural invasion by human esophageal squamous cell carcinoma are reported. Perineural invasion was observed histologically in 30 of a total of 129 cases (23%) of esophageal squamous cell carcinoma and in 11 of the 24 cases (46%) in which tumors infiltrated other organs by passing through the esophageal adventitial layer. Electron microscopic observation showed that the perineurium of peripheral nerves was completely surrounded by carcinoma cells and that marked degeneration and loss of perineural cells occurred. Irregularly thickened basal laminae were detected in the perineurium. For nerves incompletely surrounded by carcinoma tissue, the free portion of the perineurium revealed degenerative findings similar to those for completely surrounded nerves. Cytoplasmic projections of the leading margin of the invading cancer tissue were located in the degenerated perineurium, contained many lysosomes, and were not always surrounded by basal laminae. These observations suggest that invading carcinoma tissue actively contributes to the degeneration of the perineural sheath and that the special pattern of carcinoma tissue surrounding the peripheral nerves results from infiltration along the degenerated sheath of the perineurium.

Aged↗
PubMed1985

[Immunological studies on the antigenicity of the cephem antibiotic T-2588].

The antigenicity or immunological characteristics of T-2588, newly-developed ester type cephem antibiotic, was studied employing rabbits, guinea pigs and mice. The results obtained were as follows: Antibody production against T-2588 was not observed in rabbit immunized with the emulsion of T-2588 and Freund's complete adjuvant (FCA). Hapten-specific antibody production against T-2525 was demonstrated by indirect hemagglutination test and 4 hrs. PCA of guinea pigs, employing rabbit antiserum hyperimmunized with the emulsion of T-2525 coupled to rabbit serum albumin and FCA. Hapten-specific antibody production against T-2525 was demonstrated by 48 hrs. PCA of rats, employing mice immunized with the mixture of T-2525 coupled to keyhole limpet hemocyanin and aluminium hydroxide gel. Cross antigenicity of T-2525 was observed to be relatively strong against cefotaxime and ceftizoxime, and very weak against cephalothin (CET), cefazolin, cefoperazone (CPZ), cefmenoxime, cefotiam and benzylpenicillin (PCG). Anaphylactic syndrome was not observed in guinea pigs actively sensitized with the emulsion of T-2588 or T-2525 and FCA. The ability of T-2588 and T-2525 to give a positive reaction in Coombs' test was rather weaker than that of CET, CPZ and PCG.

Animals↗
PubMed1985

The response of non-pregnant rat myometrium to oxytocin in Ca-free solution.

The contractile response of the longitudinal muscle of non-pregnant rat myometrium to oxytocin (0.2-20 nM) consisted of a phasic and a tonic component. Ca-removal abolished the phasic component but a tonic contraction could be evoked without reduction of amplitude for 50 h. Exceptionally, the tonic contraction also disappeared gradually in Ca-free medium containing 2 mM EGTA. When oxytocin was repeatedly applied in the absence of Ca, the response became at first progressively larger before reaching a steady state. Transient addition of Ca to the medium reduced the size of the subsequent oxytocin contraction. In Ca-free medium, the tissue lost Ca slowly, but it still contained 40 mumol kg-1 after 6 h and roughly 1 mumol kg-1 wet weight after 24 h exposure. 45Ca efflux was marginally increased by oxytocin (20 nM). Caffeine (5-30 mM) produced no contraction, but slightly reduced the resting tension and strongly inhibited the oxytocin response both in the presence and in the absence of Ca. Caffeine also blocked the contraction induced by Ca added to Ca-free 40 mM K solution. However, pretreatment with caffeine (30 mM) had no effect on the following oxytocin response. A calmodulin antagonist, trifluoperazine (1-10 microM) suppressed strongly the Ca-induced contraction, but had only a weak effect on the oxytocin response in Ca-free medium. Chlorpromazine (10-100 microM) and fluphenazine (10-30 microM) had similar effects. A different type of antagonist, N-(6-aminohexyl)-5-chloro-1-naphthalene sulphonamide (W-7) (0.1 mM) almost completely blocked responses to both oxytocin and to Ca, but recovery of the Ca-induced contraction was much better than that of the oxytocin response in Ca-free solution. 6 Since no evidence was found for intracellular Ca release by oxytocin, and as there were several differences between the effects of calmodulin antagonists on the oxytocin response and on the Ca-induced response of similar size, the possibility remains that some Ca-independent process is involved in the contractile response to oxytocin observed in Ca-free solution.

Animals↗
PubMed1984

Effects of glucose removal and readmission on potassium contracture in the guinea-pig taenia coli.

The effects of removal and readmission of substrates on the K contracture were investigated in the guinea-pig taenia coli. When, after exposure to excess K in Ca-free and glucose-free medium, the readmission and removal of 2.4 mM-Ca were repeated at regular intervals, the Ca-induced contractions decreased progressively. The decrease was more marked in the late than in the early part of the tension response. The rate of O2 consumption decreased when the normal medium was replaced by glucose-free, Ca-free, excess-K solution, but substantially recovered following Ca readmission. ATP and creatine phosphate contents decreased during the Ca-induced contraction, but recovered partially during the subsequent relaxation in Ca-free solution. The effects of glucose removal were rapidly reversed when glucose or beta-hydroxybutyrate (beta-HB) were readmitted to the bathing solution. In the absence of Ca, readmission and removal of the substrates produced an insignificant change in O2 consumption, but the next Ca contraction was potentiated, the effect being stronger with glucose than beta-HB. When the tonic contraction evoked by 2.4 mM-Ca readmission had been abolished in glucose-free, high-K solution, a rise of the external Ca concentration to 10 mM, or 5 microM-carbachol, still produced a transient contraction. This suggests that the tonic contraction has disappeared partially because of diminished Ca influx. In glycogen-depleted preparations, the depolarization caused by carbachol, or by 20 mM-K, was increased and spike discharge initiated when glucose was readmitted.(ABSTRACT TRUNCATED AT 250 WORDS)

3-Hydroxybutyric Acid↗
PubMed1982

[General pharmacology of T-1982, a new cephamycin antibiotic].

General pharmacological studies on T-1982 produced the following results. On central nervous system, subcutaneous injection of T-1982 at dose of 2,000 mg/kg hastened the onset of pentetrazole-induced tonic extensor in mice. T-1982 had no effect on spontaneous motor activity, pentobarbital hypnosis, body temperature or EEG in mice or rabbits, and also did not show motor incoordinate, anticonvulsive or analgesic activity in mice at intravenous doses of 250--1,000 mg/kg or subcutaneous doses of 500--2,000 mg/kg. On motor and sensory nervous systems, no effect of T-1982 was noted on spinal reflex, neuromuscular junction, conduction anesthesia or surface anesthesia in rats or rabbits. On respiratory, cardiovascular and autonomic nervous systems, T-1982 caused transient increase of respiratory rate, slight hypotension and transient increase of femoral blood flow in dogs at intravenous doses of 250--1,000 mg/kg. However, it caused a slight hypertensive tendency in rabbits. Heart rate and ECG in dogs or rabbits, blood pressure response to epinephrine, isoproterenol, acetylcholine or histamine in dogs, nictitating membrane in cats and pupil size in mice were not affected after intravenous injection of T-1982. No effect was found on isolated guinea pig atrium or rabbit descending aorta following T-1982 application. On renal function in rats, T-1982 caused an increase of PSP excretion but had no effect on urine volume or electrolytes excretion at intravenous doses of 250--1,000 mg/kg. T-1982 prolonged bleeding time in mice at intravenous doses of 500--1,000 mg/kg, but did not show hemolytic property and inhibitory activity on blood coagulation or platelet aggregation in vitro experiments. Spontaneous movement and tone of isolated stomach, ileum, colon, uterus, vas deferens or trachea and acetylcholine-, histamine-, nicotine- or barium chloride-induced contraction of ileum were not affected following T-1982 application. Intestinal propulsion of barium meal in mice, gastric secretion and carrageenin-induced edema in rats were not affected after intravenous injection of T-1982. T-1982 increased bile secretion in rats dose-dependently at intravenous doses of 31.3--125 mg/kg. The local irritative activity of T-1982 in rats was slightly milder than cefoxitin and moderately milder than cefmetazole after intradermal injection. In conclusion, these results suggest that T-1982 would not cause any adverse effects at its estimated clinical doses of 10--20 mg/kg (500--1,000 mg/man).

Animals↗
PubMed1982

[Muscle irritation study on T-1982].

The local irritation effect of T-1982 after the intramuscular injection into the musculus vastus lateralis was examined in rabbits. T-1982 was dissolved by the way of clinical use and was injected singly into the musculus vastus lateralis. Then the degree of muscular injury at the time of 2 days and 7 days after the injection was judged from muscle weight ratio, gross local observation and histological observation. The degree of muscular injury caused by T-1982 was compared with that of saline, 0.75% acetic acid and 6% acetic acid. On the degree of muscular injury of T-1982 was almost equal to that of 0.75% acetic acid, but milder than 6% acetic acid. From these, it was concluded that the local irritation effect of T-1982 was grade 3.

Animals↗
PubMed1982

[The whole body autoradiographic studies on the distribution of 14C-labelled sodium 7 beta-[(2R, 3S)-2-(4-ethyl-2, 3-dioxo-1-piperazine-carboxamido)-3-hydroxybutanamido]-7 alpha-methoxy-3-[(1-methyl-1H-tetrazol-5-yl)thiomethyl]-3-cephem-4-carboxylate (14C-T-1982) in mice].

The distribution of T-1982, a new semisynthetic cephamycin antibiotic, was studied with whole body autoradiography in normal male mice, pregnant mice and experimental pyelonephritic mice following a single intravenous administration of 80 mg/kg of 14C-T-1982. 1. In normal male mice, the radioactivity was distributed at high concentration in the liver, kidney, lung, gastrointestinal tracts, skin, salivary gland, tongue and muscle, but was hardly observed in the central nervous system that composed of the brain and spinal cord. 2. In pregnant mice, the radioactivity was hardly observed in the fetuses. 3. In experimental pyelonephritic mice, considerable radioactivity was concentrated on the acute inflammatory area.

Animals↗
PubMed1982

[Studies on absorption, distribution and excretion of 14C labelled sodium 7 beta-[(2R, 3S)-2-(4-ethyl-2,3-dioxo-1-piperazinecarboxamido)-3-hydroxybutanamido]-7-methoxy-3-[(1-methyl-1H-tetrazol-5-YL)thiomethyl]-3-cephem-4-carboxylate (14C-T-1982) in mice and rats].

Absorption, distribution and excretion of sodium 7 beta-[(2R,3S)-2-(4-ethyl-2,3-dioxo-1-piperazinecarboxamido)-3-hydroxybutanamido ]-7 alpha-methoxy-3-[(1-methyl-1 H-tetrazol-5-yl) thiomethyl]-3-cephem-4-carboxylate (T-1982) were studied in rats and mice using of 14C-T-1982. 1. The binding rate of 14C-T-1982 to serum protein was about 16% in mouse, 27% in rat and 50% in human. 2. After intravenous administration to mice and rats, blood levels of radioactivity diminished rapidly. While, after subcutaneous administration to mice and intramuscular administration to rats, blood levels reached rapidly to high concentration and, declined gradually in comparison with intravenous studies. 3. Radioactivity after parenteral administration to rats and mice was distributed high into kidney, following by liver, stomach, heart, lung and ovarium, but low into brain. In new born rats, tissue levels diminished slower than that of adult rats. 4. With regard to oral administration to mice, almost all radioactivity was found in feces. This result suggested that T-1982 was hardly absorbed from gastrointestinal tracts. Urinary excretion rate after intravenous administration was about 60% in mice and 19% in rats, and the other radioactivity was found in feces. 5. In rats, radioactivity was excreted in bile at biliary excretion rate of about 80% after intravenous administration. 6. After intravenous administration to nursed rats, radioactivity was hardly detected in gastrointestinal tracts of sucklings. And from the study on distribution of radioactivity in pregnant mice, it was suggested that T-1982 scarcely passed placenta. 7. Excretion pattern after multiple administration to rats was similar to that of single administration. This result suggested that T-1982 did not produce accumulation of it in body.

Absorption↗
PubMed1980

[Muscle irritation study on cefoperazone (author's transl)].

Muscular injury caused by cefoperazone (CPZ) was compared with that of cefazolin (CEZ), cephaloridine (CER) or cephalothin (CET) in adult and juvenile male rabbits. These drugs were dissolved by the way of clinical use and were injected singly into the muscular vastus lateralis. Then, the degree of muscular injury at the time of 48 hours and 7 days after the injection was judged from muscle ratio, gross local observation and histological observations. The degree of muscular injury caused by these drugs was compared also with that of saline 075% or 6% acetic acid. The following results were obtained: There was no difference among CPZ, CEZ and CER on the degree of muscular injury and these changes were almost equal to those of 0.75% acetic acid, however severer than that of saline. While, muscular injury caused by CET was severer than that of CPZ, CEZ, CER or 0.75% acetic acid, but milder than 6% acetic acid. The inflammatory reaction against these drugs was almost similar in adult and juvenile rabbits.

Age Factors↗
PubMed1980

[Subacute toxicity test of cefoperazone in beagle dogs with the intravenous administration for 3 months (author's transl)].

The subacute toxicity test of cefoperazone (CPZ) in Beagle dogs with the intravenous administration for 35 days has been reported from our laboratory. In the present experiments, the subacute toxicity test of CPZ in Beagle dogs was carried out for longer administration period than before. CPZ was given intravenously to each group (2 or 4 dogs) at dose level of 100 mg/kg/day, 200 mg/kg/day and 400 mg/kg/day respectively for 3 months. Cefazolin (CEZ) was used intravenously for positive control using 4 dogs at dose level of 200 mg/kg/day and physiological saline was given intravenously to 2 dogs for 3 months. 1) In Beagle dogs received high dose of CPZ, transient vomiting, salivation and diarrhea were observed immediately after the administration. 2) Signs of anemia, such as decrease of erythrocyte and value of hemoglobin and hematocrit, and increase of reticulocytes of the peripheral blood and in fragility of red cell associated with decrease of food intake, were observed in 2 female dogs given CPZ of 400 mg/kg/day. In only one of these dogs, a positive reaction of COOMBS' test was shown. The anemia recognized in these 2 dogs seems to be of hemolytic nature. 3) The weight of thymus was decreased in all of 4 dogs given CPZ at 400 mg/kg/day and in 2 out of 4 dogs given CPZ at 200 mg/kg/day, respectively. 4) Based on the fact that no abnormalities were found in dogs given CPZ at 200 mg/kg/day except a slight decrease of weight of thymus in some of them, the maximum safety dose of CPZ was thought to be 200 mg/kg/day.

Animals↗