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Biomedical subjects

T Araki

Publications and source records attributed to T Araki.

At least 343 records · Page 19Linked to original sources
PubMed1996

Effects of cerebral ischemia on dopamine receptors in the gerbil striatum.

Dopamine D1 and D2 receptors and uptake sites were studied in the gerbil striatum and frontal cortex 1 h to 7 days after 10 min of cerebral ischemia caused by occlusion of the bilateral common carotid arteries. [3H]SCH23390 ([N-methyl-3H]R[+]-8-chloro-2, 3,4,5-tetrahydro-3-methyl-5-phenyl-7-ol-benzazepine), [3H]nemonapride and [3H]mazindol were used as markers of dopamine D1 receptors, D2 receptors and uptake sites, respectively. A significant reduction in [3H] SCH23390 binding was found in the striatum from 48 h after ischemia. In contrast, during the recirculation periods, [3H]nemonapride and [3H]mazindol binding was mostly unaffected in this region which was the most vulnerable to ischemia. The frontal cortex, where ischemic neuronal damage was mild, also showed no significant changes in [3H]SCH23390, [3H]nemonapride and [3H]mazindol binding after ischemia. Thus, cerebral ischemia that was associated with cell loss in the striatum resulted in a selective reduction of dopamine D1 receptors and not D2 receptors. No changes in dopamine D1 or D2 receptors were observed in frontal cortex. If massive dopamine release occurs with cerebral ischemia, it is not reflected by modification in the number of uptake sites located on dopamine terminals.

Animals↗
PubMed1996

p53 involves cytosine arabinoside-induced apoptosis in cultured cerebellar granule neurons.

The tumor suppressor p53 gene plays a key role in controlling the cell cycle checkpoint and in apoptosis following the exposure of normal cells to DNA damage. To investigate the role of p53 in cytosine arabinoside (Ara C)-induced cell death of CNS neurons, we examined the effect of Ara C on the survival of cultured cerebellar granule neurons from normal wild-type and p53 null mutant mice. When the neurons from wild-type mice were cultured with Ara C, they gradually died after 24 h in culture. In contrast, the neurons from p53 null mutant mice showed a resistance to the Ara C neurotoxicity. These results indicate that p53 involves Ara C-induced apoptosis in cultured cerebellar granule neurons, in which DNA damage may initiate the apoptotic death program of the neurons.

Animals↗
PubMed1996

First-trimester prenatal molecular diagnosis of infantile hypophosphatasia in a Japanese family.

We obtained a prenatal molecular diagnosis during the first trimester in a Japanese woman whose first child (the proband) had been a compound heterozygote for infantile hypophosphatasia. We examined chorionic villus DNA samples obtained at 10 weeks of gestation for the base substitutions detected in the proband DNA using polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) and PCR-allele-specific oligonucleotide (ASO) analysis. The genotype of the fetus was the same as that of the proband. The same mobility shift patterns of single strand conformation polymorphism (SSCP) bands were observed in the fetus and the proband. This molecular approach to prenatal diagnosis appears to be more accurate than the enzymatic method and also more accurate and more rapid than the conventional RFLP method.

Alleles↗
PubMed1996

Thermoregulatory responses of prepubertal boys and young men in changing temperature linearly from 28 to 15 degrees C.

To examine thermoregulatory responses of prepubertal children to cold stress, 11 boys (aged 8 years) and 11 young men (aged 19-23 years), wearing only trunks, participated in this study. They sat in air at 28 degrees C for 30 min (equilibrium period) and then in conditions where air temperature (Ta) was decreased linearly from 28 to 15 degrees C (at a constant rate of 0.22 degrees C.min-1) for 60 min, at a fixed relative humidity of 65%. In the equilibrium period there was no significant difference between the groups for rectal temperature [Tre, mean 37.30 (SEM 0.10) and mean 37.43 (SEM 0.14) degree C in the boys and the men, respectively] or for the respective skin temperatures (except for the forehead), but metabolic heat production (M) was significantly greater for the boys [mean 57.1 (SEM 1.2) and mean 52.0 (SEM 0.9) W.m-2, P < 0.005]. With declining Ta, the skin temperatures decreased in both groups (P < 0.001), but the decrease was significantly greater for the boys (P < 0.05), especially on the limbs as represented by the thigh and forearm. No significant correlations were observed between the limb skin temperatures compared to surface area-to-mass ratio or limb skinfold thicknesses in either group. The rate of increase in M as Ta decreased was significantly lower for the boys (P < 0.01) largely because of a higher M before the cold exposure. Thus, the mean M during the cold exposure did not differ between the groups [mean 63.6 (SEM 1.1) and mean 61.6 (SEM 1.1) W.m-2 in boys and men, respectively]. When the Ta was lowered, Tre in the boys started falling (P < 0.001), whereas the Tre in the young men did not change for 60 min. The Tre during the 60-min exposure was significantly lower (P < 0.001) for the boys [mean 37.01 (SEM 0.13) and mean 37.48 (SEM 0.18) degree C at the end of the exposure]. It was concluded that when Ta was lowered, the prepubertal boys appeared to vasoconstrict more in their limbs and to be somewhat more hypothermic, compared to the young men.

Adolescent↗
PubMed1996

Clothing microclimate temperatures during thermal comfort in boys, young and older men.

To examine the effects of age-related differences in thermoregulatory function on the clothing microclimate temperature (Tm) and Tm fluctuations while maintaining thermal comfort in daily life, 5 boys (group B, 10-11 years), 5 young men (group Y, 20-21 years) and 5 older men (group O, 60-65 years) volunteered to take part in this study. The subjects were asked to maintain thermal comfort as closely as possible in their daily lives. Tm (temperatures between the skin surface and the innermost garment) at four sites (chest, back, upper arm, and thigh), skin temperature on the chest (Tchest) and ambient temperature (Ta) were measured over a period of 8-12 h from morning to evening on one day in each of the seasons, spring, summer, autumn, and winter. Records of ability to maintain thermal comfort and of adjustment of their clothes were kept by each subject. Ta during periods of thermal comfort did not differ among the groups in any of the seasons. In group Y, Tm was significantly lower at the thigh than at the other sites in spring, autumn, and winter (P < 0.05) and fluctuations (CV) of Tm were significantly larger at the thigh than at other sites in autumn and winter (P < 0.05). Similar tendencies were observed for Tm and CV of Tm in group B. However, Tm and CV of Tm in group O did not differ by site except for the autumn Tm. Group O had a smaller CV at the thigh in winter (P < 0.05), compared to groups B and Y, suggesting a smaller regional difference in Tm fluctuation in group O. Group O adjusted their clothes even on the lower limbs (together with upper body) in order to maintain thermal comfort in accordance with changes in Ta, while groups B and Y did so only on their upper bodies. These results suggest that compared to boys and young men, lower thermoregulatory function in older men may affect Tm and CV of Tm as a result of clothing on lower limbs being adjusted differently in order to maintain thermal comfort.

Adult↗
PubMed1996

Age-related change of mineral content in the human thoracic aorta and in the human cerebral artery.

The relative contents (RCs) of mineral elements in aortae and cerebral arteries from 23 subjects, with ages ranging between 45 and 99 yr, were analyzed by inductively coupled plasma atomic emission spectrometry. The RCs of calcium, phosphorus, and magnesium in the aortae increased markedly after the age of 70. While the RC of sulfur in aortae decreased gradually after that age. It was found that accumulation of calcium and phosphorus occurred primarily in the tunica media of aorta, and secondarily in the tunica intima. Furthermore, the RCs of calcium, phosphorus, and magnesium in cerebral arteries increased markedly after the age of 70, whereas the RC of sulfur in cerebral arteries decreased after age 70. It was found that accumulation of calcium and phosphorus in the cerebral arteries were 30 and 60%, respectively, lower than those in the aortae with ages ranging between 45 and 99 yr.

Aged↗
PubMed1996

Tl-201 uptake and retention in a Warthin's tumor.

We report scan findings of Tl-201 in a case of histologically proved Warthin's tumor. Dual isotopes acquisition was performed in a case of left parotid Warthin's tumor. Both early and delayed Tc-99m-pertechnetate (Tc-99m) images showed increased uptake at the tumor. Tl-201 scan also showed an increase of uptake on the early image and retention on the delayed image. The uptake ratios of Tl-201 were 3.0 (early) and 2.3 (delayed). Scan findings of Tl-201 in a case of Warthin's tumor were similar to those of Tc-99m, and the interpretation of Tl-201 images should be accompanied with Tc-99m images.

Adenolymphoma↗
PubMed1996

Uptake and washout of I-123-MIBG in neuronal and non-neuronal sites in rat hearts: relationship to renal clearance.

We investigated the uptake and washout of I-123-metaiodobenzylguanidine (MIBG) in neuronal (both intra- and extravesicular) and non-neuronal sites in the heart and its relationship to renal clearance. Acute renal failure was induced in rats by ligating the renal vessels, and the findings were compared with those of sham-operated rats. Each group consisted of control, reserpine-treated and 6-hydroxydopamine (6-OHDA)-treated subgroups. Rats were sacrificed at 10 minutes and 4 hours after injection of MIBG. MIBG activity was calculated in specimens of heart, spleen, lung and blood. At 10 minutes, no significant difference in MIBG uptake in the heart was observed among the subgroups or between sham-operated and renal failure rats despite a significantly higher blood MIBG activity in the latter. At 4 hours, however, the hearts of both reserpine-treated and 6-OHDA-treated rats showed significantly lower MIBG uptake than control rats. Furthermore, the hearts of renal failure rats showed higher MIBG uptake in the control and reserpine-treated rats than in the corresponding subgroups in sham-operated rats. Intra and extravesicular neuronal uptake of MIBG in the heart were estimated using control, reserpine-treated and 6-OHDA-treated rats. Vesicular uptake values were similar in both the sham-operated group (0.51% ID/g) and the renal failure group (0.44% ID/g). But extravesicular neuronal uptake values were quite different in the renal failure group (0.86% ID/g) and the sham-operated group (0.19% ID/g). In conclusion, uptake to and washout from extravesicular neuronal sites may depend on the concentration of MIBG in the blood or the state of renal clearance, but vesicular uptake may be independent of these factors.

3-Iodobenzylguanidine↗
PubMed1996

Application of Tc-99m-tetrofosmin as a tumor imaging agent: comparison with Tl-201.

Tc-99m-tetrofosmin SPECT was performed on 6 occasions in 4 patients with hypopharyngeal carcinoma, lung carcinoma, esophageal carcinoma and maxillary plasmocytoma and compared with Tl-201 SPECT. All lesions accumulated both Tc-99m-tetrofosmin and Tl-201. Early uptake ratios of Tc-99m-tetrofosmin were about 2 but those of Tl-201 were much higher (more than 3). Washout rates of Tc-99m-tetrofosmin were higher than those of Tl-201. There was a good positive correlation between the early uptake ratio of Tc-99m-tetrofosmin and that of Tl-201. The delayed uptake ratio and washout rate showed poor correlation. In conclusion, early uptakes of both the agents were similar but their retention patterns were different. Tc-99m-tetrofosmin may be used for tumor imaging though more studies are required to evaluate diagnostic accuracy and the significance of delayed images.

Aged↗
PubMed1996

The relationship between uterine artery Doppler velocimetry and umbilical venous adenosine levels in pregnancies complicated by preeclampsia.

OBJECTIVE: The aim of this study was to evaluate the relationship between uteroplacental circulatory insufficiency and the fetoplacental release of adenosine in pregnancies complicated by preeclampsia. STUDY DESIGN: We performed uterine artery Doppler velocimetry and calculated the pulsatility index of the uterine artery, to detect uteroplacental circulatory insufficiency, immediately before cordocentesis in 39 pregnant women complicated by preeclampsia. Umbilical venous blood obtained by cordocentesis was then analyzed for blood gases, pH, and plasma adenosine levels. Increased plasma adenosine was taken to signal its increased release from the placenta and fetus relative to its rate of disappearance. RESULTS: The mean umbilical venous plasma adenosine level in the abnormal pulsatility index group was 1.78 +/- 0.17 mumol/L (mean +/- SEM, n = 25), significantly higher than in the normal pulsatility index group 0.58 +/- 0.14 mumol/L (n = 14, p < 0.001). Furthermore, in the abnormal pulsatility index group the elevation of plasma adenosine levels in the umbilical vein was found even in normoxic fetuses. CONCLUSION: Fetal plasma adenosine increases before uteroplacental circulatory insufficiency becomes severe enough to cause generalized fetal hypoxemia. We postulate that enhanced adenosine formation in the fetus, umbilical cord vessels, and particularly the placenta may, at least in part, contribute to control and maintenance of placental blood flow.

Adenosine↗
PubMed1996

Maternal theophylline administration and breathing movements in late-gestation human fetuses.

OBJECTIVE: To investigate the relation between maternal administration of theophylline and breathing movements during late gestation in human fetuses. METHODS: After a 1-hour control period, 17 women with normally grown fetuses at 33-38 weeks' gestation were given 400 mg of sustained-release theophylline orally. Maternal plasma theophylline and glucose concentrations were measured every hour, and the incidence of fetal breathing movements and breathing rates were measured continuously during the next 8 hours. Results were compared with those of a similar control group that did not receive theophylline. RESULTS: The maternal plasma theophylline concentration increased to detectable levels after 1 hour, reached therapeutic levels of 6.9 +/- 0.4 micrograms/mL (standard error of the mean) after 6 hours, and thereafter averaged 8.3 +/- 0.3 micrograms/mL, significantly higher than initial control values (P < .05). The mean glucose concentration was unchanged during the first 6 hours (79.2 +/- 1.1 mg/dL) and then decreased somewhat, averaging 75.8 +/- 1.1 mg/dL in the 7-8 hour period. The incidence of fetal breathing increased 26.4 +/- 1.9% after 5 hours and remained elevated during the next 3 hours at levels significantly higher than in the initial control period (P < .05) and higher than in the control group that did not receive theophylline. The mean hourly breathing rate averaged 40.9 +/- 1.3 breaths per minute after ingestion of theophylline, a nonsignificant change. CONCLUSIONS: Ingestion of theophylline by pregnant women in late gestation is associated with an increase in fetal breathing movements. Theophylline has been used widely in the management of asthma in pregnancy, and the assessment of fetal breathing movements is used routinely for evaluation of fetal status. Therefore, account must be taken of changes in breathing movements caused by maternal theophylline administration.

Adult↗
PubMed1996

Ninjurin, a novel adhesion molecule, is induced by nerve injury and promotes axonal growth.

Peripheral nerve injury results in axonal degeneration and in phenotypic changes of the surrounding Schwann cells, whose presence is critical for nerve regeneration. Using differential screening strategies, we identified a novel protein, termed ninjurin (for nerve injury-induced protein), that is up-regulated after axotomy in neurons and in Schwann cells surrounding the distal nerve segment. Ninjurin is located on the cell surface, is capable of mediating homophilic adhesion, and promotes neurite extension of dorsal root ganglion neurons in vitro. Ninjurin is also expressed in a number of other tissues, predominantly in epithelial cells. These results suggest that ninjurin plays a role in nerve regeneration and in the formation and function of other tissues.

Amino Acid Sequence↗
PubMed1996

Changes in M-CSF-like activity during chicken embryonic development.

We have established a method for separation of chicken bone-marrow cells using Percoll density gradient centrifugation, and have developed a new method for determining chicken M-CSF-like activity employing a liquid culture. Using this method, we determined M-CSF-like activities in egg yolk, chorioallantoic fluid (CAF) and amniotic fluid (AmF), and studied the effects of M-CSF on development of chicken embryos. M-CSF-like activity in egg yolk was at a high level before the incubation of the egg; it began to decrease on the third day of incubation and rapidly decreased on the fourth day, and no significant activity was detected after the tenth day of incubation. M-CSF-like activity in CAF was very low, and it exhibited almost no change during development. No M-CSF-like activity was detected in AmF throughout the experimental period.

Allantois↗
PubMed1996

Involvement of p53 in DNA strand break-induced apoptosis in postmitotic CNS neurons.

The tumour suppressor p53 gene serves as a critical regulator of the cell cycle and of apoptosis following the exposure of normal cells to DNA damage. To examine the role of p53 in postmitotic CNS neurons, we cultured cerebellar neurons from normal wild-type mice and mutant p53-null mice under various conditions inducing neuronal death. When cerebellar neurons from 15- to 16-day postnatal wild-type mice were treated with ionizing radiation or DNA-damaging agents, massive neuron death occurred after 24-72 h. In contrast, neurons from p53-/- mice evidently resisted gamma-irradiation and some DNA-damaging agents, such as etoposide and bleomycin. On the other hand, low-K+ medium-induced apoptosis of cerebellar neurons was not affected by p53 status. Neither cell cycle progression nor DNA synthesis occurred during cell death induced by gamma-irradiation and low-K+ medium, as well as in normal cultures of p53+/+ and p53-/- neurons. These results suggest that p53 is required for the apoptotic death of postmitotic cerebellar neurons induced by DNA strand breaks.

Animals↗
PubMed1996

Studies on the magnitude and the mechanism of cough potentiation by angiotensin-converting enzyme inhibitors in guinea-pigs: involvement of bradykinin in the potentiation.

One adverse effect of the angiotensin-converting enzyme (ACE) inhibitors used for treatment of hypertension and congestive heart failure is the production of dry coughs. Imidapril is a new type of ACE inhibitor with a very low incidence of coughs. The magnitude and the mechanism of cough potentiation of imidapril and other ACE inhibitors has been studied in guinea-pigs. In normal guinea-pigs single and repeated dosing of imidapril at 0.1 to 100 mg kg-1 had no effect on capasaicin- or citric acid-induced coughs. Single and repeated dosing of enalapril and captopril at 10 to 30 mg kg-1, respectively, significantly increased the number of capsaicin-induced coughs. Repeated dosing of 1 mg kg-1 enalapril also significantly augmented the capsaicin cough. In bronchitic guinea-pigs imidapril also had no effect on the coughs induced by the two stimulants. Enalapril and captopril significantly increased the number of coughs induced not only by capsaicin but also by citric acid. Lower doses of enalapril were enough to augment the capsaicin-induced coughs, whereas medium to large doses failed to augment the cough irrespective of the protocol of administration. Bradykinin-induced discharges of the vegal afferents from the lower airway were significantly increased by enalaprilat but not by imidaprilat. Capsaicin-induced discharges of the afferents were, on the other hand, significantly depressed by enalaprilat, but not by imidaprilat. Interestingly, enalaprilat depression of the discharges was significantly reversed by Hoe-140, a bradykinin B2 receptor blocker. In guinea-pigs pretreated with a low dose of enalapril, arterial infusion of bradykinin significantly potentiated the coughs induced by capsaicin. The results indicated that imidapril was less potent than enalapril and captopril in potentiating cough responses induced by capsaicin and citric acid in guinea-pigs, and further suggest that bradykinin might be a key substance in the mechanism of the potentiation of coughs associated with ACE inhibitors.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1996

[A case of amoebiasis as a latent infection].

A 69-year-old male was admitted because of constipation and abdominal distension. A colon fiberscopic examination revealed the formation of ulceration. The trophozite of Entamoeba histolytica was detected from from the specimens of colon mucosal biopsy of the ulcer. The stool was positive for the cysts of E. histolytica too. He had been in China and Southeast Asia during World War II. He returned home and experienced amoebic dysentry, and was treated with Emethin hydrochlolide. He suffered from amoebic disentry in 1970 and was treated with Emethine hydrochrolide again. After the War he had not gone abroad, and was not a homosexual. So this case was considered a latent infection of E. histolytica from the War. This time he was treated with metronidazol and minocycline. After the therapy, cysts were negative in the stool and the ulcer was cured on the colon fiberscopic examination.

Aged↗
PubMed1996

Plasma endothelin-1 levels during asphyxia in the fetal goat.

The changes in fetal carotid arterial plasma levels of endothelin-1, catecholamines, PO2, PCO2 and pH were measured after intermittent repetitive umbilical cord occlusion in late gestation pregnant goats (n = 9). Endothelin-1 levels increased to 3.58 +/- 0.28 pg/ml immediately after the onset of fetal hypoxia, a level significantly higher than the respective values in the control period (p < 0.05). The elevation of fetal plasma endothelin-1 levels correlated inversely with carotid arterial PO2 (r = -0.41, p < 0.05) and pH (r = - 0.43, p < 0.05). The results suggest that increased endothelin-1 levels may contribute to the maintenance of the fetal circulation during fetal asphyxia.

Animals↗