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Biomedical subjects

K Ashida

Publications and source records attributed to K Ashida.

At least 91 records · Page 5Linked to original sources
PubMed1994

Quantitation of rCBF by 99mTc-hexamethylpropyleneamine oxime single photon emission computed tomography combined with 133Xe CBF.

A simple, noninvasive method of measuring CBF that uses single photon emission computed tomography (SPECT) of 99mTc-hexamethylpropyleneamine oxime (99mTc-HMPAO) and whole-brain CBF obtained by 133Xe clearance technique was developed. SPECT data were normalized to the count density of HMPAO uptake in the whole brain and then converted to the absolute units of CBF by multiplying average CBF in the whole brain obtained by 133Xe. Mean CBF values in healthy volunteers (n = 12) were 49 +/- 7 and 30 +/- 5 ml 100 g-1 min-1 for gray matter and white matter, respectively, with a global flow value of 45 +/- 5 ml 100 g-1 min-1. The mean flow value was 19 +/- 7 ml 100 g-1 min-1 for the core of the infarct and 31 +/- 5 ml 100 g-1 min-1 for the contralateral region (n = 13). CBF values were reproducible for all brain regions. The method was convenient to use and suitable for the routine measurement of regional CBF in normal and pathologic states.

Cerebrovascular Circulation↗
PubMed1994

Pharmacokinetics and pharmacodynamics of famotidine in children with gastroduodenal ulcers.

We treated 14 boys, six with gastric ulcers and eight with duodenal ulcers, to determine famotidine pharmacokinetics and its inhibition of gastric acid secretion (pharmacodynamics). Famotidine (1 mg/kg/day) was administered either intravenously or orally at a dose of 0.5 mg/kg twice a day (maximum: 40 mg/day). Blood samples were collected from all subjects and the intragastric pH monitored in eight. Pharmacokinetic parameters were calculated assuming a one-compartment model. Volume of distribution, elimination half-life, and area under the serum concentration-time curve were 1.52 +/- 0.37 l/kg, 2.29 +/- 0.38 h, and 1.14 +/- 0.32 ng.h/ml, respectively. The mean oral bioavailability of famotidine was 50.6%. Both intravenously and orally administered famotidine neutralized gastric acidity during sleep but failed to continuously maintain the intragastric pH > 5.0. All subjects' ulcers healed within 8 weeks. There were no side effects noted during famotidine treatment. Twice daily administration of 0.5 mg/kg famotidine for 8 weeks appears to be a tolerated and effective treatment of children with gastroduodenal ulcers.

Administration, Oral↗
PubMed1994

Decreased cerebrovascular dilatory capacity in subjects with asymptomatic periventricular hyperintensities.

BACKGROUND AND PURPOSE: The clinical significance of the periventricular hyperintensity incidentally found on magnetic resonance images of the brain is questionable. We evaluated resting cerebral blood flow and cerebrovascular dilatory capacity of subjects with asymptomatic periventricular hyperintensities to study their cerebral hemodynamics. METHODS: Magnetic resonance imaging of the brain was performed in 28 asymptomatic subjects with cerebrovascular risk factors to determine the severity of periventricular hyperintensity. Mean gray matter flow was computed by a 133Xe-clearance technique in subjects at rest and after the administration of 1 g acetazolamide. Flow values were correlated with the scores for periventricular hyperintensity. RESULTS: Resting gray matter flow was not significantly correlated with the severity of periventricular hyperintensity for the whole brain (rs = -.364), whereas flow after acetazolamide loading (rs = -.783, P < .001) and the absolute value of increased flow (rs = -.567, P < .01) were significantly and negatively correlated with the severity of periventricular hyperintensity. CONCLUSIONS: A decrease in vasodilatory capacity and compensatory vasodilation occur in the cerebral cortex of subjects with asymptomatic periventricular lesions and maintain cerebral blood flow.

Aged↗
PubMed1994

Fine structural aspects on auditory hair cell degeneration in the budgerigar, Melopsittacus undulatus, as induced by kanamycin.

The effects of kanamycin, an antibiotic of the aminoglycoside group, on the auditory sensory epithelium of the budgerigar, Melopsittacus undulatus, were examined using both scanning and transmission electron microscopes. Results show that the threshold of the auditory brainstem response increased in birds treated with kanamycin 200 mg/kg for 49 days. While the auditory sensory epithelium of the normal budgerigar consists of short and tall hair cells, and supporting cells, following kanamycin administration, the middle to proximal region of the epithelium of the inner ear showed degenerative changes, with the other parts remaining apparently intact. In the damaged region, the short hair cells were flattened, and the tall ones became heterogeneous in shape. Both types of cells contained many dense bodies in their cytoplasm; they were rounded in shape and homogeneously dense. Severely degenerated tall hair cells also contained many large vacuoles with heterogeneous contents. Because the dense bodies and large vacuoles were positive for acid phosphatase reaction, they were respectively judged to be primary lysosomes and secondary lysosomes containing degenerating cell debris. Most supporting cells in the impaired region were lower in cytoplasmic electron density, and their apical surface became enlarged in area. Some flattened short hair cells were situated on the apical part of the swollen supporting cells. This finding suggests that the short hair cells are pressed toward the scala media by the supporting cells.

Animals↗
PubMed1994

[Quantitation of regional cerebral blood flow by single photon emission computed tomography of CBF-tracer combined with whole-brain CBF: a comparison between 123I-IMP and 99mTc-HMPAO in healthy volunteers].

A simple, noninvasive method of measuring cerebral blood flow (CBF) that uses single-photon emission computed tomography (SPECT) of CBF-tracer and whole brain CBF obtained by xenon-133 (133Xe) clearance technique was developed. In nine healthy volunteers, SPECT data were normalized to the count density of 123I-IMP or 99mTc-HMPAO uptake in the whole-brain, and then converted to the absolute units of CBF by multiplying average 133Xe-CBF in the whole brain. The CBF values measured by 99mTc-HMPAO CBF-SPECT was significantly lower in the high flow regions of cortical gray matter (bilateral frontal lobe; p < 0.05 and right occipital lobe; p < 0.05), and was significantly higher in the bilateral white matter (p < 0.05 or 0.01) and the cerebellum (p < 0.005) compared with the flow values measured by 123I-IMP CBF-SPECT. Whereas, the IMP-CBF values were significantly lower in the bilateral striatum (p < 0.02 or 0.05) compared with the HMPAO-CBF values. Good correlations were found between IMP-CBF and the HMPAO-CBF values in the cortical gray matter (rs = 0.761; p < 0.001, n = 108), the white matter (rs = 0.739; p < 0.001, n = 18) and the cerebellum (rs = 0.731; p < 0.001, n = 18). In the striatum (rs = 0.58; p < 0.05, n = 18) and the thalamus (rs = 0.628; p < 0.05, n = 18), the correlations between IMP-CBF and HMPAO-CBF values were inferior to those of the other three regions.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Factors causing prolonged hypoperfusion after transient ischemic attack.

Even during the symptom-free stages, patients with a TIA often experience cerebral blood flow disturbances. In order to evaluate the factors which cause this abnormality, we studied the cerebral blood flow disturbance, anatomy and clinical status in 21 patients after TIAs. The results of 99mTc-hexamethyl-propylene-amine oxime SPECT were compared with CT, cerebral angiogram, cerebrovascular risk factors and clinical findings to determine which factor is most responsible for the hypoperfusion of brain after TIA. The overall sensitivity rates in detecting a lesion were 67% in SPECT and 19% in CT. The hypoperfused area tended to be large in patients who had intracranial, severe stenotic, multiple, or hemodynamically significant arterial lesions on the ipsilateral side. No such relationships were found between other examinations. We conclude that hypoperfusion after TIA essentially reflects a continuous cerebral blood flow disturbance that can be attributed to atherosclerosis of the cerebral arteries, with subsequent embolic and/or hemodynamic cerebral ischemia, although there may be a variety of processes.

Adult↗
PubMed1993

Complete recanalization of total occlusion in abdominal aorta by intra-aortic infusion of a thrombolytic agent--a case report.

Complete recanalization was achieved by intra-aortic infusion of urokinase in a case of complete occlusion of the abdominal aorta. The patient was a fifty-nine-year-old man with atrial fibrillation, hypertension, and diabetes mellitus who was admitted because of intermittent claudication and pain in both lower extremities at rest. Angiography demonstrated complete obstruction of the abdominal aorta, but the bilateral iliac arteries were visualized via collaterals. Urokinase was administered intra-aortically in a total dose of 1,200,000 U during the first day and a total dose of 960,000 U during the second day. The aorta and the iliac arteries recanalized after this treatment, and complete recanalization associated with disappearance of subjective symptoms was observed after one month of treatment with warfarin. The present case suggests the usefulness of intra-arterial infusion of urokinase for the treatment of complete occlusion of the abdominal aorta.

Aorta, Abdominal↗
PubMed1993

Cerebral blood flow in asymptomatic individuals--relationship with cerebrovascular risk factors and magnetic resonance imaging signal abnormalities.

We studied the relationship between cortical grey matter flow (CBF) and age, cerebrovascular risk factors and the severity of subcortical hypersignals (HS, hyperintensity score in MRI) in 47 asymptomatic subjects with cerebrovascular risk factors. Multiple regression analysis revealed that HS was most strongly related to CBF, and that hematocrit, age and evidence of ischemic change detected in the electrocardiogram also appeared to be independent determinants of CBF. Both the severity and location of hypersignals were correlated with CBF. The most significant negative correlation observed was that between CBF and HS in the basal ganglia-thalamic region, where the degree of signal abnormality was modest. Decreased CBF in asymptomatic subjects with cerebrovascular risk factors may be related to (1) microcirculatory disturbance associated with elevated hematocrit and an increase in the number of risk factors, and (2) functional suppression of cerebral cortex due to the neuronal disconnection associated with subcortical lesions. In addition, impaired cerebral circulation may be related to MRI signal abnormalities.

Adult↗
PubMed1993

Disappearance of pulmonary metastases by OK-432 treatment in a case of hepatocellular carcinoma.

We report here a case of hepatocellular carcinoma (HCC) with multiple lung metastases, which were disappeared by treatment of OK-432. The patient was a 65-year-old man and was diagnosed in 1986 with a small (17 x 11 mm) HCC in the anterior-superior segment of the liver. A part of the right hepatic lobe including the tumor was surgically removed, and transarterial injections of adriamycin (10 mg/week) and subcutaneous injections of OK-432 (10 KE/week) were given. Two and a half years later, recurrence of HCC in the liver and its invasion to vena cava inferior (IVC) were found. OK-432 administration was then stopped and percutaneous ethanol injection therapy (PEIT) was performed 10 times. Six months later, the PEIT was effective and the liver tumor with IVC invasion diminished. However, multiple lung metastases were visible on roentgenograms of the chest, and serum alphafetoprotein (AFP) concentration increased to 50,000 ng/ml. The OK-432 treatment resumed. After 6 months of OK-432 treatment, the multiple lung metastases were disappeared and the serum AFP level decreased to 100 ng/ml. At present, the patient is surviving without any sign of recurrence in either the liver or the lung. The clinical course of this case suggests that OK-432 might have effectively treated lung metastases of HCC, although the exact mechanisms are at present unclear.

Aged↗
PubMed1993

The ultrastructure of the basilar papilla of the budgerigar's inner ear.

The basilar papilla in the inner ear of the adult budgerigar was studied by scanning and transmission electron microscopy. The sickle-shaped basilar papilla has short hair bundles on the proximal tip and long ones on the distal tip. The tectorial membrane shows a honeycomb-like pattern and enclosed a hair bundle in its alveolus. The papilla consists of two different types of hair cells; short and tall hair cells. The short hair cells with large efferent nerve endings are located on the free basilar membrane in the inferior part. The tall hair cells with large afferent nerve endings are located in the superior part. The similarity and difference of the structure are discussed between the budgerigar and other birds, and between birds and mammals.

Animals↗
PubMed1993

Effect of chronic smoking on regional cerebral blood flow in asymptomatic individuals.

Correlations between cigarette smoking and cerebral blood flow (CBF) were determined. The purpose of the present study was to determine whether the level of cigarette use is a significant predictor of regional CBF (rCBF) when age, gender, mean arterial blood pressure, total cholesterol, fasting blood glucose, hematocrit, and presence of ST-T change and left ventricular hypertrophy on electrocardiogram (ECG) are controlled. We studied a continuous sample of 40 asymptomatic individuals including 20 smokers and 20 nonsmokers. Subjects (mean age 66.2 yr) had an average smoking index of 456 +/- 485.1 (mean +/- standard deviation) [(Number of cigarette/d) x (years of smoking history)]. Regional CBF was measured using the intravenous 133Xe injection method. Simple linear regression and multivariate regression analyses were performed, which modeled regional cerebral blood flow as a function of smoking index and other cerebrovascular disease risk factors. The male-to-female ratio was higher in the group of smokers (18/2) than in the group of nonsmokers (2/18) (P < 0.01). The mean hematocrit of smokers was significantly higher than that of nonsmokers (P < 0.01). There were no significant differences in other variables tested between the two groups. Simple linear regression analysis demonstrated a significant negative correlation of smoking index with CBF in whole brain (r = -0.33; P < 0.05), the right hemisphere (r = -0.34; P < 0.05), right parietal cortex (r = -0.36; P < 0.05), right occipital cortex (r = -0.34; P < 0.05) and left parietal cortex (r = -0.33; P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1993

[The relationship of periventricular hyperintensity with cerebral blood flow and cerebrovascular reserve capacity in asymptomatic individuals].

Although periventricular hyperintensity (PVH) is frequently detected in elderly persons by magnetic resonance imaging (MRI), the relationship of such lesions with cerebral blood flow (CBF) and cerebrovascular reserve capacity has never been determined. We used acetazolamide-enhanced xenon-133 CBF and MRI to study 28 subjects with one or more cerebrovascular risk factors but with no neurological symptoms. According to MRI examinations on the transaxial slice of the body of the lateral ventricle, 10 subjects had no PVH (group O), 7 a partial PVH (group I), 6 a continuous PVH (group II), and 5 a confluent PVH which spreads over a wide area of the white matter (group III). There was no relationship between the severity of PVH and the resting cortical CBF (F = 2.7). However, the severity of PVH showed significant negative relationships with the acetazolamide-enhanced CBF (F = 9.5; p < 0.01), and the absolute increase of CBF from the resting state to the acetazolamide challenge (F = 5.1; p < 0.01). Our data suggest the importance of hemodynamic factors and the compensatory vasodilation in the pathogenesis of PVH in asymptomatic individuals.

Acetazolamide↗
PubMed1993

Cerebral blood flow and magnetic resonance imaging in locked-in syndrome.

The cerebral blood flow (CBF) of a patient suffering from locked-in syndrome (LiS) was examined before and after the onset using 99mTc-hexamethylpropyleneamine oxime single-photon emission computed tomography (SPECT) and the intravenous 133Xe injection method. The mean CBF during the locked-in state was 32.2 ml/100 g/min, a 42% reduction from the asymptomatic stage. SPECT showed profound reductions of perfusion in the bilateral cerebral cortices, subcortical regions and in the cerebellum, with a less marked reduction in the frontal cortices. On Day 49, the patient showed some minimal voluntary return with a moderate increase in mean CBF of 40.2 ml/100 g/min. The relative CBF values in the cerebral cortices and subcortical regions were restored, but the bilateral cerebellar hypoperfusion remained unchanged. SPECT and CBF are useful for a better characterization of the brain pathophysiology in LiS.

Aged↗
PubMed1992

[A case of complete recanalization in the lower abdominal aorta by intraaortic infusion of a thrombolytic agent].

Intraarterial infusion of thrombolytic agent is useful in the treatment of obstructive arterial diseases in various vessels. However, few studies have shown that this treatment is useful for aortic occlusion. We report the case with complete recanalization in the lower abdominal aorta following intraaortic infusion of a thrombolytic agent. A 59-year-old man was admitted because of weakness and pain in the bilateral lower limbs at rest. Aortography showed complete occlusion of the abdominal aorta proximal to the inferior mesenteric artery. Both external arteries were supplied via rich collaterals. He was treated by intraaortic urokinase infusion of 2,100,000 units. Total recanalization in the abdominal aorta and both common iliac arteries was obtained. Intraaortic infusion of urokinase was shown to be effective treatment of occlusion in the abdominal aorta.

Aorta, Abdominal↗
PubMed1992

[Effect of chronic smoking on regional cerebral blood flow in asymptomatic individuals].

The chronic effects of cigarette smoking upon regional cerebral blood flow (rCBF) are unclear. The present study investigated the effects of smoking on rCBF assessed by intravenous 133Xe injection in 40 asymptomatic individuals. Analysis was performed using linear regression analysis and multiple regression analysis, creating a model of the rCBF as a function of cerebrovascular risk factor. The risk factors included smoking status, smoking index, age, gender, mean arterial blood pressure, total cholesterol, fasting blood glucose, hematocrit and STT change and left ventricular hypertrophy in electrocardiogram. The male-to-female ratio was higher in the smoking group (18/2) than that in the non-smoking group (2/18). Among the smokers, mean hematocrit was significantly higher than in the non-smokers (p < 0.01). There was no significant difference in rCBF and other variables between the two groups. Linear regression analysis revealed significantly negative correlations between smoking index and CBF in the whole brain (r = -0.33; p < 0.05), right hemisphere (r = -0.34; p < 0.05), right parietal cortex (r = -0.36; p < 0.05), right occipital cortex (r = -0.34; p < 0.05) and left parietal cortex (r = -0.33; p < 0.05). In other variables, age, male sex, hematocrit, left ventricular hypertrophy and STT change showed significantly negative correlations with rCBF. To reduce the effect of confounding variables in our assessment of the dose-related response, a multivariate regression analysis was carried out treating rCBF as a dependent variable and risk factors as independent variables. In the final model, age, hematocrit, male sex and presence of BCG changes remained as independent negative predictors for rCBF.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1992

[Cerebral blood flow distribution and reactivity during the symptom-free stages of transient ischemic attacks--a 99mTc-HMPAO SPECT study].

Even during the symptom-free stages, patients with transient ischemic attacks (TIA) often show cerebral blood flow (CBF) disturbances. For evaluating the factors which cause these abnormalities, we studied CBF and CBF reactivity to acetazolamide (Diamox) using a 99mTc-hexamethylpropyleneamine oxime (HMPAO) single photon emission computed tomography (SPECT). The results from CBF-SPECT were compared with X-ray computed tomography (CT), cerebral arteriogram, clinical characteristics of TIA and cerebrovascular risk factors. The overall sensitivity rates in detecting the lesion were 68% in CBF-SPECT and 9% in CT. The size of the hypoperfused area tended to be wide in patients who had intracranial, severe stenotic or multiple arterial lesions on the ipsilateral side. No such relations were found between CBF and other examinations. Brain hypoperfusion was located in the subcortical region in eight patients; two patients showed a small hypodense lesion on CT which corresponded to the hypoperfusion on SPECT, and three patients showed no arteriographic abnormality. Hypoperfusion in the cortex was seen in seven patients; all patients showed arteriographic abnormality, but no CT abnormality. The severity rating of the vascular stenosis and hypoperfusion, and the incidence of the intracranial lesions were higher in this group than the group with subcotical hypoperfusion. Seven patients showed fixed normoperfusion before and after diamox injection. Two patients with a subcortical small infarction showed fixed hypoperfusion even after diamox injection. Twelve patients showed focal hypoperfusion before diamox with a new filling-in after diamox. Only one patient showed resting hypoperfusion and decreased CBF reactivity to diamox.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetazolamide↗
PubMed1992

[Comparison of vulnerability between avian and mammalian inner ears--electrophysiological and morphological studies].

In order to assess the vulnerability of the inner ear, auditory function and morphology of the inner ear were compared between adult budgerigars and adult guinea pigs. Budgerigars have been considered to have an excellent auditory-vocal system. Two experimental conditions were produced in each species; one by acoustic hyperstimulation (1500 Hz, 120 dBSPL) for 96 hours, the other by administration of kanamycin (200 mg/kg) for 7 weeks. Measurement of auditory evoked potentials (AEP) and observation of hair cells by electron microscopy were performed both immediately and 14 days after exposure. In the acoustic hyperstimulation experiment, AEPs of budgerigars showed less damage and better recovery than those of guinea pigs, probably because of morphological differences between the two species in hair and supporting cells. Electron microscopic observation on the budgerigars showed that a small part of the hair cell area was damaged and that regeneration of hair cells had occurred in this area 14 days after exposure. Such observations in guinea pigs revealed that outer hair cells had been damaged and replaced by supporting cells 14 days after exposure. In the kanamycin administration experiment, AEPs showed the same degree of damage and recovery in both species. This suggests that blood supply and drug transport to the inner ear are almost the same although the structure of the inner ear differs markedly between the two species. Electron microscopic observation did not show an apparent regeneration of hair cells 14 days after administration in the budgerigars. Guinea pigs had a tendency to show progressive damage of both auditory function and inner ear morphology even after the cessation of administration. Regeneration of hair cells in the budgerigar differed under both experimental conditions, suggesting that there is a difference in the mode of auditory disturbance between acoustic hyperstimulation and administration of kanamycin. In conclusion, resistance to acoustic hyperstimulation is higher in the avian inner ear than in the mammalian inner ear, while resistance to administration of kanamycin does not differ significantly between the two species.

Acoustic Stimulation↗