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Biomedical subjects

T Misawa

Publications and source records attributed to T Misawa.

At least 109 records · Page 6Linked to original sources
PubMed1989

Critical period of brain development in learning caused by lead exposure in rats.

Three groups of rats (group a, b and c) with high and stable avoidance, and low variability, named Tokai High Avoiders (THA) strain. (a) via placenta from the 13th day of gestation, through maternal milk during lactation and per os after weaning (group Pb-gestation), (b) through maternal milk during lactation and per os after weaning (group Pb-birth), (c) per os after wearing (group Pb-weaning). The pre- and postnatal lead exposure induced apparent delays in speed of learning acquisition and broke the uniformity in avoidance rate in both males and females. Postnatal lead exposure caused slight delays in speed of learning acquisition in males alone. In the post wearing period defect in learning due to lead exposure could be observed in both males and females. No apparent difference was present in the development of pups among the lead exposed groups and control. From these results, it could be deduced that the most sensitive period of brain development in learning affected by lead exposure was the pre- and early postnatal period in the rat.

Age Factors↗
PubMed1989

[Assessment of the left atrial myxoma with gated blood pool SPECT].

A left atrial myxoma with 4 cm diameter was studied with ECG gated Tc-99m blood pool SPECT. The long axial images showed the myxoma to protrude through the mitral valve (MV) during diastole and to come back into the atrium in systole. No significant atrial dilatation due to the MV obstruction was detected. The ejection fraction calculated from the SPECT images was 10% lower than that of the conventional method viewed from LAO 45 degrees. Nuclear medicine gave an additional information for the assessment of the hemodynamics.

Aged↗
PubMed1989

Neurobehavioral analysis of high-rate Sidman avoidance rat strain.

The neurobehavioral characteristics of the Tokai High-Avoider (THA) rats, which had an innate high-avoidance ability, were clarified by comparing with the Wistar rats from which the THA rat strain had been derived. THA rats performed superior learning and displayed small individual differences of learning performance, not only in the Sidman avoidance task, which had already been used in selective breeding, but also in two different tasks, namely water maze and two-way shuttle avoidance. No apparent difference was present in development, circadian rhythm, and open-field activity between the two strains. On the other hand, sensitivity of the THA rat to electric shock or to heat stress was less than that of the Wistar rat. From these results, it might be considered that the high and uniform avoidance performance exhibited in the THA rat was caused by an innately acquired ability but not by sensitivity to the shock or developmental differences.

Animals↗
PubMed1988

Endoscopic appearance of the intussuscepted appendix and accurate preoperative diagnosis.

Intussusception of the appendix in a 25-yr-old man was diagnosed preoperatively. Only six such cases have been reported. This patient presented with episodes of recurrent severe right lower abdominal pain, each episode separated by several uneventful months. The diagnosis was made by radiological visualization of a polypoid lesion with a dimple at the top in the caput cecum, and by the endoscopic appearance of the polypoid mass. A sessile polypoid mass (about 1 cm) that looked like foreskin and glans was observed by colonoscopy. The dimple at the top, like glans, was partially reddish, and the steeply sloped surface, like foreskin turned inside out, was smooth. The area of dimple at the top became discernibly smaller and the appearance changed as air was led into cecum. Appendectomy was without untoward events, and the patient no longer experienced such episodes. Although intussusception of the appendix is rare, it should be included in the differential diagnosis of acute abdominal syndrome.

Adult↗
PubMed1987

Effects of H2-receptor antagonists on 3H-cimetidine binding and histamine-stimulation of cellular cAMP in isolated guinea pig gastric glands.

3H-Cimetidine binding to plasma membranes of isolated guinea pig gastric glands was investigated, and the effects of five H2-receptor antagonists on 3H-cimetidine binding and histamine stimulation of cellular cAMP were compared. Of the five cations tested, Cu++ markedly increased specific 3H-cimetidine binding. 3H-Cimetidine had high affinity (Kd = 0.41 x 10(-6) M) and low affinity (Kd = 12.8 x 10(-6) M) binding sites. Cimetidine and etintidine were potent inhibitors of 3H-cimetidine binding, while famotidine, ranitidine and TZU-0460 were not. Histamine stimulation of cellular cAMP was competitively inhibited by H2-receptor antagonists yielding pA2 values of 6.41 for cimetidine, 6.82 for etintidine, 6.87 for ranitidine, 6.94 for TZU-0460 and 7.60 for famotidine. Because the KB value (log KB = -pA2) of 0.39 x 10(-6) M for cimetidine is close to the Kd value for the high affinity 3H-cimetidine binding site, it is presumed to represent a part of the H2-receptor, and the relative potency of etintidine against cimetidine in inhibiting 3H-cimetidine binding is similar to that in inhibiting histamine stimulation of cellular cAMP. These results suggest that imidazole-derived H2-receptor antagonists (cimetidine and etintidine) and non-imidazole H2-receptor antagonists (famotidine, ranitidine and TZU-0460) compete with histamine at different sites on the H2-receptor of the gastric glands.

Animals↗
PubMed1987

Visualization of right atrial thrombus associated with constrictive pericarditis by indium-111 oxine platelet imaging.

A right atrial thrombus is not often seen and only a few reports of visualization have been described. We report a 44-yr-old man who had a large atrial thrombus associated with constrictive pericarditis. Two-dimensional echocardiography and computed tomography showed a large right atrial mass. Indium-111 oxine platelet deposition was demonstrated on the surface of thrombus by platelet imaging. Platelet imaging was useful for differential diagnosis from cardiac tumor, and as an indication for surgical treatment, since right atrial thrombus may have a high risk of pulmonary embolism or severe right heart failure.

Adult↗
PubMed1987

Pharmacokinetics of pirenzepine in patients with gastric or duodenal ulcers.

1. The pharmacokinetics of pirenzepine (Gastrozepin) was studied after single and multiple oral administration in gastric ulcer and duodenal ulcer patients. 2. With a dose of 50 mg of pirenzepine, plasma levels reached a maximum 2 h after the administration in both groups (gastric ulcer patients: 57.2 +/- 31.8 ng/ml, duodenal ulcer patients: 48.0 +/- 18.0 ng/ml), and decreased bi-phasically with an elimination half-life (t1/2 beta) of 13.9 +/- 4.0 and 17.9 +/- 4.5 h, respectively. The area under the plasma level curve were 844 +/- 319 ng X h/ml and 663 +/- 151 ng X h/ml in the respective group. 3. The plasma levels of pirenzepine after multiple administration (50 mg was given as a loading dose, and thereafter 25 mg was given as a maintenance dose at an interval of 12 h for 7 days) maintained certain steady state levels from just after the start of administration. 4. It can be concluded that there is no significant difference in the pharmacokinetics of pirenzepine between gastric and duodenal ulcer patients. It can be judged that twice-daily administration of pirenzepine is enough for ulcer treatment.

Administration, Oral↗
PubMed1986

Effects of hexamethonium and atropine on the basal levels of immunoreactive vasoactive intestinal polypeptide in dogs.

The basal levels of immunoreactive vasoactive intestinal polypeptide (IR-VIP) in veins of the gastrointestinal tract and the effect of hexamethonium and atropine on basal levels of IR-VIP were examined in anesthetized dogs. The basal mean plasma IR-VIP levels in the pancreaticoduodenal vein, the mesenteric vein of the jejunum, the mesenteric vein of the ileum and the right colonic vein, but not the left gastroepiploic vein, were significantly higher than those in the femoral vein. These basal levels of IR-VIP were decreased by atropine, but not by hexamethonium. Thus, the main source of basal VIP in the portal vein is probably the duodenum (and pancreas) and the small and large intestine, and the basal levels of VIP are under the control of muscarinic receptors, in canine gastrointestinal tract.

Animals↗
PubMed1986

Inhibitory effect of etintidine (BL-5641), a new type of H2 receptor antagonist, on binding of [3H]-cimetidine to plasma membrane and histamine-stimulated cellular cAMP production in isolated guinea pig gastric glands.

A comparative study was carried out between the inhibitory effects of cimetidine and those of etintidine (BL-5641), a new type of H2 receptor antagonist, on the binding of [3H]-cimetidine to plasma membranes as well as on histamine-stimulated cellular cAMP production in isolated guinea pig gastric glands. Both cimetidine and etintidine inhibited the binding of [3H]-cimetidine to plasma membranes, in a dose-dependent manner, with an IC50 of 1.70 X 10(-6) M and 0.51 X 10(-6) M, respectively. The two drugs also inhibited histamine-stimulated cellular cAMP production in a dose-dependent manner, shifting the histamine dose-dependent curve of cellular cAMP production to the right. The PA2 calculated from the result obtained was 6.41 for cimetidine and 6.82 for etintidine. These results indicate that etintidine is an H2 receptor antagonist at the cellular level and that its inhibitory effect is approximately 2.5 times as potent as that of cimetidine.

Animals↗
PubMed1986

Evidence of local mechanism involvement in vasoactive intestinal polypeptide release from canine small intestine.

We studied the effect of intraileal administration of a 100-ml test meal, 100 ml of 5% glucose, amino acids, 10% Intralipos, or bile on canine plasma immunoreactive vasoactive intestinal polypeptide (VIP) levels in the mesenteric and femoral veins of dogs. The effects of intravenous administration of caerulein on plasma immunoreactive VIP levels were examined, with or without intraduodenal ballooning, to rule out the effect of bile and pancreatic and gastric juice. In addition, hexamethonium bromide or atropine sulfate was given intravenously before the administration of bile or intravenous caerulein to study the role of the neural pathway on the release of VIP. Basal plasma VIP levels in the mesenteric vein were significantly higher than those in the femoral vein. Intraileal administration of the test meal, 5% glucose, amino acids, or 10% Intralipos induced no variation of mesenteric VIP. Intraileal administration of bile or intravenous caerulein, with or without intraduodenal ballooning, produced a significant increase of plasma VIP in the mesenteric vein. Pretreatment with atropine completely blocked the bile-stimulated VIP release and significantly inhibited the caerulein-stimulated release of VIP. On the other hand, pretreatment with hexamethonium did not significantly decrease the VIP response by bile or caerulein. Thus, the muscarinic receptor probably plays an important role in bile- or caerulein-stimulated release of VIP.

Amino Acids↗
PubMed1986

[An experimental study of work load on VDT performance. Part 1. Effects of polarity of screen and color of display].

Study were made on the effects of polarity of screen and color of display on work load of VDT tasks. The subjects of the present experiment were eight healthy male college students (age: 21-23 yr) having a naked binocular vision of not less than 0.7 and no astigmatism nor hyperopia. The test consisted of an experimental word processing task in which the subjects visually searched e's in given sequences of alphabetical letters displayed on the CRT and converted them to 5's through keyboard operation. As for experimental conditions, four levels of screen image, that is, positive and negative screens and green and white colored displays were adopted and 2 hr were given for each operation time. Critical flicker fusion (CFF), near point distance, accommodation time, subjective fatigue symptoms, heart rate, electromyogram in upper limbs and performance score were measured. The following results were obtained. Decrease in C.F.F. and extension of near point distance were observed in all experimental conditions during the operating time. Increase in complaints of subjective fatigue related to visual function was observed in all experimental conditions after two hour VDT task. Greater extension of near point distance and larger complaints of subjective fatigue were observed in subjects using the green colored display than in those using the white colored display. This suggests that the visual load using the green colored display is larger than that using the white colored display. A larger decreased in C.F.F. and greater complaints of subjective fatigue were demonstrated in subjects using negative screen than those using positive screen. This suggests that the visual load using the negative screen is larger than that using the positive screen.

Adult↗
PubMed1986

[Effects of peri- and postnatal lead administration on learning of high avoider rats].

Effects of administration of lead acetate on Sidman avoidance behavior were assessed in juvenile and adult rats which were obtained by continued selective breeding and which have a high level avoidance ability and small individual differences (THA rat: Tokai high avoider rat). THA rats were administered lead acetate solution at 200-300 mg/kg/day as Pb until 7 wk of age through maternal milk before weaning from mothers which had been administered lead acetate from the 13th day of gestation and per os by gastric tube after weaning. Three series of Sidman avoidance behavior tests were conducted from 49th, 100th and 150th day after birth each for 10 d, 1 h every day. In the first series, a significant delay of shock avoidance acquisition was observed in lead-administered male rats compared with the control subjects, while no acquisition delay was seen in female rats. The lead administered male rats could be divided into two groups with different response patterns; a low susceptible group (LSG) which exhibited as good acquisition rate from the beginning similar to the control rats and a high susceptible group (HSG) which showed a significant delay and individual differences. In the 2nd test series, very high avoidance rates were obtained in all the test groups except in male HSG, but in the 3rd test series, male HSG also attained a final acquisition of high avoidance rate. There was no developmental variation between the groups nor difference in lead contents of the organs of the exposed group. Useful characteristics of THA rats for behavioral toxicology are discussed.

Animals↗
PubMed1986

[Effects of low level toluene exposure during the developing stage of the brain on learning in high avoider rats].

THA (Tokai High Avoiders) rats were exposed in the exposure chambers to 100 and 500 ppm of toluene and air for 7 h every day from 13th day of gestation to 48 d of age. After the termination of toluene exposure, Sidman avoidance test was conducted on the rats for 10 d from 49 d of age (first test series), 100 d of age (second test series) and 150 d of age (third test series). The results obtained are as follows. No difference could be observed between the toluene exposed groups and controls in the initiation of pinna detachment, primary coat of downy hair, incisor eruption and eye opening. The body weight of the 100 ppm exposed group was slightly greater than that of the control and the 500 ppm exposed group. No difference was indicated between these three groups in reflex and locomotor activity. Avoidance learning: Avoidance rate in the two exposed groups of male rats was significantly lower than those in the control during the 60 min of the test in the first test series. The magnitude of individual variations of avoidance rate in the two exposed groups of male rats was also remarkably greater than that of the control. No difference was seen between the two exposed groups in both avoidance rate and magnitude of avoidance variation. In the second and third test series, the avoidance rate of the two exposed groups still did not attain the control levels during the period of the test series. In female rats, the avoidance rate of the two exposed groups during the first 30 min of the test in the first test series was slightly lower than the control. This difference in avoidance rate observed between the exposed groups and the control disappeared during the latter 30 min of the test. In the second and third test series, the avoidance rate of both exposed groups reached the control level during the test period. It may be concluded from the foregoing findings that 100 ppm and 500 ppm toluene exposure during the fetal and suckling periods affects learning in the rats after termination of the growth period, and that the learning disorder still remained as long as 100 days after the end of toluene exposure, although the effect decreased gradually. It was also observed that this learning disorder appeared more distinctly in male rats than in female rats.

Animals↗
PubMed1986

[An experimental study of work load on VDT performance. Part 2. Effects of difference in input devices].

Effects of the difference in input device on work load of VDT task were studied. The subjects of the experiment were eight healthy male college students (age: 21-22 yr) having a binocular vision of not less than 0.7 and no astigmatism or hyperopia. The test consisted of an experimental word processing task in which the subjects visually searched e's in given sequences of alphabetical letters displayed on the CRT and converted them to 5's through input device operation. As for experimental conditions, two kinds of input devices, namely, keyboard and lightpen were adopted and 1 h was provided as each operation time. Critical flicker fusion (CFF), near point distance, accommodation time, subjective fatigue symptoms, blinking counts, pupillary reflex, electromyogram in upper limb, neck and shoulder and performance score were measured. The results were as follows. Decrease in C.F.F. was observed in two experimental conditions during the process of operating time. Increments in complaints of subjective fatigue related to visual function were seen in the two experimental conditions after 1 h VDT task. A higher error rate in performance was observed in the subjects using the lightpen compared to the one using the keyboard. The frequency of both blinking and pupil-size changes were lower in the subjects using the lightpen compared to those using the keyboard. This suggests that the gaze time of the VDT screen with lightpen-condition is longer than that in keyboard-condition.(ABSTRACT TRUNCATED AT 250 WORDS)

Accommodation, Ocular↗