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Biomedical subjects

A Otsuka

Publications and source records attributed to A Otsuka.

At least 37 records · Page 2Linked to original sources
PubMed1998

[Bilateral homonymous hemianopsia with atrial fibrillation].

We encountered an 80-year-old man with sudden bilateral visual disturbance. When he was admitted to the hospital, his blood pressure was 138/70 mmHg, and an ECG revealed atrial fibrillation. Neurological examination showed only bilateral homonymous hemianopsia with no nystagmus or impairment of eye movement. He did not have paralysis cerebellar ataxia, or speech disturbance. Therefore, there was no evidence of obstruction of the thalamogeniculate or thalamoperforating artery. Magnetic resonance imaging of the brain showed cerebral infarctions in both occipital lobes. Perimetry showed bilateral homonymous hemianopsia; the left side of the macula was spared. The lack of neurological deficit other than bilateral homonymous hemianopsia indicates that only the right and left cortical branches of the posterior cerebral artery were occluded.

Aged↗
PubMed1997

[Outpatient chemotherapy with continuous intravenous infusion for patients with recurrent renal cell carcinoma or advanced prostate carcinoma].

We tried outpatient chemotherapy with continuous intravenous infusion of 5-fluorouracil (5-FU) and cisplatin (CDDP) for patients with recurrent renal cell carcinoma or advanced prostate carcinoma. This study was designed to evaluate the efficacy of our drug delivery system using two disposable balloon pumps and subcutaneous port, subjective symptoms caused by chemotherapy, and quality of life (QOL). There were 12 patients, including 7 cases of recurrent renal cell carcinoma and 5 cases of advanced prostate carcinoma. Their performance status (PS) was grade 0 or 1. The protocol for renal cell carcinoma consisted of combined chemotherapy with continuous infusion of 5-FU 250 mg/m2/day and CDDP 3 mg/m2/day in 2 weeks for 1 cycles (4 weeks). 5-FU and CDDP were administered with the Baxter infuser pumps (Intermate LV 1.5) and after 1 week we changed the new pumps. In treating advanced prostate carcinoma, Honvan 100 mg/day was substituted for 5-FU. We experienced 2 cases of problems with the drug delivery system during 10 months, which needed a change of the subcutaneous port. QOL score and subjective symptoms showed that patients were not always free because of carrying pumps and the side effects of chemotherapy, but they can return to social life and family instead of spending much time in the hospital. In conclusion, our drug delivery system is safe for outpatient chemotherapy, and QOL of patients with home anti-cancer chemotherapy is higher than that of patients with chemotherapy in the hospital.

Adult↗
PubMed1996

Preparation and evaluation of a compressed tablet rapidly disintegrating in the oral cavity.

In order to make a compressed tablet which can rapidly disintegrate in the oral cavity, microcrystalline cellulose and low-substituted hydroxypropylcellulose were used as disintegrants, and ethenzamide and ascorbic acid were chosen as poorly and easily water soluble model drugs, respectively. The mixture of microcrystalline cellulose and low-substituted hydroxypropylcellulose was compressed at 100--500 kgf in the absence of an active ingredient. The properties of these tablets, such as hardness, porosity, the time required for complete wetting of a tested tablet (wetting time), water uptake and disintegration time determined by a new disintegration apparatus, were investigated to elucidate the wetting and disintegration characteristics of these tablets, When the MCC/L-HPC ratio was in the range of 8:2 to 9:1, the shortest disintegration time was observed. The disintegration of tablets containing ethenzamide or ascorbic acid was examined next. Tablet disintegration time in the oral cavity was also tested, and good correlation between the disintegration behaviors in vitro and in the oral cavity was recognized.

Ascorbic Acid↗
PubMed1996

Intracranial hypoglossal neurinoma without preoperative hypoglossal nerve paresis--case report.

A 46-year-old female presented with an intracranial hypoglossal neurinoma manifesting only as spasticity in the lower extremities without hypoglossal nerve paresis. Magnetic resonance imaging greatly aided in the early detection of the tumor with this atypical presentation. Unilateral suboccipital craniotomy with resection of the occipital condyle allowed us to approach the tumor in front of the medulla from an inferolateral direction and to remove it successfully. We emphasize the need to pack dead space with fatty tissue to prevent cerebrospinal fluid leakage.

Cranial Nerve Neoplasms↗
PubMed1996

Herniation of the third ventricle into empty sella caused by surgery for pituitary apoplexy--case report.

A 46-year-old male presented with acute visual loss in the right eye, high fever, nausea, and vomiting. This was caused by herniation of the third ventricle into empty sella at 15 months of surgery for pituitary apoplexy. The sellar-suprasellar tumor was totally removed via a transcranial approach. Histological examination showed chromophobe adenoma with necrotic tissue, indicating pituitary apoplexy. His visual field defect worsened 15 months after the operation, and magnetic resonance imaging revealed moderate hydrocephalus and protrusion of the dilated anterior inferior portion of the third ventricle into the sella. The optic nerve, optic chiasm, and pituitary gland were compressed onto the sellar floor. Ventriculoperitoneal shunt relieved the visual impairment. A decompressive procedure such as ventriculoperitoneal shunts is a reasonable treatment for such a marked herniation of the third ventricle.

Cerebral Ventricles↗
PubMed1995

Angiotensin II type 1a receptor-deficient mice with hypotension and hyperreninemia.

Angiotensin (AT) II, the bioactive octapeptide in the renin-angiotensin system that plays a key role in cardiovascular homeostasis, exerts its multiple effects through the different types of AT receptors, AT1a, AT1b, and AT2. Previously, we showed chronic hypotension in angiotensinogen (the precursor of AT)-deficient mice and a dramatic increase in renin mRNA levels in its kidney, but it remains unclear which types of AT receptors regulate the blood pressure and renin gene expression. In order to elucidate the physiological roles of AT1a receptor, we generated mutant mice with a targeted replacement of the AT1a receptor loci by the lacZ gene. In the heterozygous mutant mice, the strong lacZ staining was found in the glomerulus and juxtaglomerular apparatus of the renal cortex, which coincided with that of the signals detected by in situ hybridization. Chronic hypotension was observed in the heterozygous and homozygous mutant mice, with 10 and 22 mm Hg lower systolic blood pressure, respectively, than that of wild-type littermates. Both levels of renin mRNA in the kidney and plasma renin activity were markedly increased only in the homozygous mutant mice. These results demonstrated that an AT1a-mediated signal transduction pathway is, at least in part, involved in the regulation of blood pressure and renin gene expression.

Angiotensin II↗
PubMed1995

Amino acids in the medulla oblongata contribute to baroreflex modulation by angiotensin II.

We investigated the underlying mechanisms of baroreflex alteration produced by intravenous angiotensin II (ANG II) by monitoring the release of amino acids from the rostral ventrolateral medulla (VLM) using a brain microdialysis technique. Reflex changes in heart rate were elicited by bolus intravenous injection of phenylephrine (2-40 micrograms/kg) before and 120 min after the initiation of administration of a subpressor dose of ANG II (5.4 pmol/kg/min) or vehicle. The slope of the regression line obtained from changes in mean arterial pressure and heart rate elicited by phenylephrine was used as an index of baroreceptor reflex sensitivity. ANG II administration for 120 min significantly attenuated the baroreflex sensitivity (from -0.59 +/- 0.10 to -0.30 +/- 0.08 bpm/mmHg). This attenuation was accompanied with an increase in the release of glutamate and glycine from the VLM (+40% and +20%, respectively) at 120 min. Glycine perfusion into this area resulted in an attenuation of baroreflex sensitivity with a magnitude similar to that obtained with infusion of a subpressor dose of ANG II, whereas glutamate perfusion caused a resetting of baroreflex. These results suggest that glycine and glutamate are involved in cardiovascular regulation in the VLM. Furthermore, the augmented releases of these amino acids may account for the underlying mechanism of ANG II-induced attenuation of baroreflex function.

Amino Acids↗
PubMed1995

Release of lidocaine from polymer film dosage forms.

We investigated the in vitro drug release from mixed polymer films using lidocaine (LC), which is poorly water-soluble. The mixed polymer films consisted of various ratios of hydroxypropylcellulose (HPC) and hydroxypropylmethylcellulose phthalate (HPMCP). The effects of the presence glycyrrhizic acid (GL) or polyethylene glycol (PEG) in the films upon LC release were also studied. LC crystallinity decreased in the polymer film and this decrease was remarkable in the presence of GL, resulting in an amorphous state. During the initial stage, drug release was regarded as a zero-order dissolution. The apparent release rate constant, ka, varied with the ratios of the two polymers and the amount of additives as well as with the pH of the test solution. The results indicated that GL enhanced the dissolution rate of LC from mixed polymer films, which may be due to the formation of an amorphous state. On the other hand, since PEG is a surfactant, the enhanced wettability of the polymer by the buffered solutions may have caused the increased dissolution rate.

Calorimetry, Differential Scanning↗
PubMed1994

Differential control of vascular tone and heart rate by different amino acid neurotransmitters in the rostral ventrolateral medulla of the rat.

1. To test the hypothesis that a central mechanism may play a role in the minimal reflex tachycardia noted in response to peripheral converting enzyme inhibition, we compared the effects of intravenous (i.v.) ceronapril (CER) with nitroglycerin (NTG) on neurotransmitter release in the rostral ventrolateral medulla (RVLM), using an in vivo microdialysis method in pentobarbital anaesthetized rats. 2. CER (0.1 mg/kg, i.v.) caused a progressive decrease in glutamate (GLU) release (CER 65 +/- 7% vs NTG 83 +/- 3% of each baseline at 140 min, P < 0.05) and attenuated the increase in glycine (GLY) release (CER 100 +/- 8% vs NTG 122 +/- 9%, P < 0.05). 3. Prevention of blood pressure reduction due to i.v. CER by concomitant infusion of a subpressor dose of angiotensin II (AII) attenuated the progressive reduction of GLU release (87 +/- 4%, P < 0.05 compared with NTG group), whereas GLY release was not affected (106 +/- 5%, NS compared with NTG group). 4. Perfusion of GLU into this area at approximately physiological concentrations resulted in a sustained tachycardia with an attenuation of the depressor effect of i.v. CER and perfusion of GLY solely lowered blood pressure. 5. These results demonstrate that i.v. converting enzyme inhibitor reduces the release of GLU in the RVLM, which was specifically caused by reducing circulating AII, without any effect on GLY release, thus resulting in the reduction of blood pressure with minimal effect on the heart rate.

Anesthesia↗
PubMed1994

Release of isosorbide dinitrate from polymer film dosage forms and absorption of this drug through the oral mucosa of rats.

In vitro release tests and in vivo absorption measurements of oral cavity dosage forms of isosorbide dinitrate (ISDN) prepared from mixed polymer film systems were conducted. Hydroxypropylcellulose (HPC) and hydroxypropylmethylcellulose phthalate (HPMCP) were used to make the films, and the tests were conducted with films made from various ratios of these two polymers. The effects of the addition of the accelerator glycyrrhizic acid (GL), on dissolution and absorption were also examined. The mean dissolution time (MDT) in the in vitro dissolution tests varied with the nature of the polymers and drug, as well as with the pH of the testing solution. The MDT for the polymer film system with GL was smaller than that without GL. In the in vivo absorption tests using rats, the absorption of ISDN through the oral mucosa was observed in all the systems. In the mixed polymer film systems, the mean residence time (MRT) increased with increasing the ratio of HPMCP/HPC. The values of the area under the curve (AUC) for the systems with GL was larger than for those without GL. A good correlation was demonstrated between the absorption rate constant, ka and the dissolution rate constant, kd.

Absorption↗
PubMed1994

Long-term therapy with terazosin may improve glucose and lipid metabolism in hypertensives: a multicenter prospective study.

The effects of long-term monotherapy with terazosin, an alpha-1 blocker, on blood pressure, glucose tolerance, and serum lipid profiles were prospectively investigated in 53 hypertensive patients: 19 with normal glucose tolerance (NGT) and 34 with impaired glucose tolerance (IGT). The plasma glucose, serum lipids, fructosamine, and glycosylated hemoglobin A1c (HbA1c) levels were determined before and during long-term (6 months) therapy with terazosin. A 75-g oral glucose tolerance test was performed before and during long-term terazosin therapy. Significant falls in both systolic and diastolic blood pressure in both patient groups were maintained during the long-term therapy with terazosin. Neither fasting nor postglucose-load venous plasma glucose levels were altered in either group of patients, and diabetes mellitus did not develop in any patient with NGT during the study. There was no significant change in the insulinogenic index (delta IRI/delta BS at 30 minutes after glucose load) in either patient group. In patients with IGT, glucose intolerance was slightly improved with significant reductions in HbA1c and fructosamine during terazosin therapy. Serum total cholesterol (TC) and triglyceride levels were significantly decreased in patients with IGT. In addition, TC and low density lipoprotein (LDL) cholesterol were significantly decreased in patients with hypercholesterolemia (TC > 220 mg/dL). These results suggest that long-term therapy with terazosin may improve glucose and lipid metabolism in hypertensive patients and terazosin seems to be an antihypertensive agent with beneficial effects for hypertensive patients with either dyslipidemia or impaired glucose metabolism.

Adrenergic alpha-Antagonists↗
PubMed1993

Evaluation of orthostatic hypotension using power spectral analysis.

To evaluate the pathogenesis of orthostatic hypotension, we studied the autonomic regulation system by measuring heart rate variability during 60 degrees passive head-up tilt using power spectral analysis in 21 patients with orthostatic hypotension (mean age 62 +/- 2 years, five with histories of cerebrovascular accidents, five with Parkinsonism, five with diabetes mellitus, three with pheochromocytoma, and three with unknown causes) and 15 normal healthy subjects as a control (mean age 63 +/- 2 years). We also assessed plasma epinephrine and norepinephrine response to tilt. During tilt, control subjects showed an increase in heart rate with no change in blood pressure. Spectral analysis of heart rate variability demonstrated increases in the low frequency band (LFB, mainly sympathetic) and low frequency band/high frequency band ratio (LFB/HFB, sympatho-vagal balance). All patients with orthostatic hypotension showed a significant reduction in blood pressure with an increase in heart rate. In patients with histories of cerebrovascular accidents and with Parkinsonism, LFB and the LFB/HFB ratio did not increase. However, in other patients with orthostatic hypotension, LFB and the LFB/HFB ratio increased during tilt. Norepinephrine increased in control subjects and in patients with diabetes mellitus, pheochromocytoma, and unknown causes. In contrast, patients with histories of cerebrovascular accidents and patients with Parkinsonism showed no increase in norepinephrine. Epinephrine responses paralleled those of norepinephrine, but the changes were not significant. Thus, neurological response to tilt is not uniform in patients with orthostatic hypotension. Patients with histories of cerebrovascular accidents and patients with Parkinsonism may have impaired function of central neural mechanisms controlling blood pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Pressure↗
PubMed1992

Spectral change in heart rate variability in response to mental arithmetic before and after the beta-adrenoceptor blocker, carteolol.

Spectral analysis of heart rate fluctuation was evaluated before and after administration of carteolol, a non-selective beta-adrenoceptor-blocker, to investigate the neural regulatory mechanisms underlying the haemodynamic changes induced by mental stress. Mental stress increased blood pressure and heart rate, with an increased low frequency band, and low frequency/high frequency ratio of the power spectral analysis which are indices of sympathetic activity. Carteolol did not change basal and pre-mental stress measurements of blood pressure, heart rate and spectral density. However, carteolol altered the response to mental stress with a decrease in spectral density of the low frequency band and low frequency/high frequency ratio, and an increase in the high frequency component. These results confirm that mental stress elevates blood pressure by activating the sympathetic nervous system, and suggest that blockade of the beta-adrenoceptor attenuates the pressor response by preventing the autonomic responses to mental stress.

Blood Pressure↗
PubMed1992

[An elderly case of hypertension with persistent orthostatic hypotension].

The authors report the successful control of labile hypertension associated with orthostatic hypotension in a 75-year-old male patient, by means of L-DOPS, a synthetic precursor of norepinephrine in combination with antihypertensive drugs. He had been known to be hypertensive for 15 years and developed a persistent floating sensation 2 years age. Despite good control of hypertension after admission, orthostatic hypotension was still observed. Passive tilt produced a blood pressure reduction of 60/20 mmHg. Spectral analysis of heart rate variability showed a disturbance in the activation of the sympathetic nervous system. Treatment with L-DOPS attenuated the blood pressure reduction in response to passive tilt (35/12 mmHg) and improved the sympathetic response. Because of an increase in blood pressure by L-DOPS, addition of either a calcium channel blocker or an angiotensin-converting enzyme inhibitor was necessary. These combinations of treatment successfully controlled blood pressure as well as orthostatic hypotension.

Aged↗
PubMed1991

Comparative study of the effects of three angiotensin converting enzyme inhibitors on the cough reflex.

To compare the effects of three different angiotensin converting enzyme (ACE) inhibitors on the cough reflex, capsaicin and citric acid challenge tests were done in normal subjects and hypertensive patients before and after administration of delapril, captopril, or enalapril. Two groups of 7 normal subjects (single dose study: 15 mg delapril v 18.75 mg captopril or 2.5 mg enalapril) and a group of 6 mildly hypertensive patients (1 week study: cross-over administration of 30 mg/day delapril, 37.5 mg/day captopril, or 5 mg/day enalapril) were studied. Another group of 6 patients with essential hypertension was treated with three ACE inhibitors for 4 weeks in a randomized order, with a 2 week washout period between active therapies. Aerosols of 1 mumol/L and 3 mumol/L capsaicin and 0.68% citric acid in 0.9% NaCl were generated by an ultrasonic nebulizer, and the frequency of cough was counted during inhalation. Delapril treatment resulted in substantially fewer patients with a significant increase (greater than or equal to 4 coughs during treatment than during the control period) in the frequency of cough than did captopril treatment. In the 1 and 4 week studies, enalapril and captopril had substantially more occurrences of significantly increased capsaicin-induced cough than did delapril. These results indicate that delapril has the least cough stimulatory effect among these ACE inhibitors, which may be clinically beneficial.

Administration, Inhalation↗
PubMed1991

Interferon-gamma inhibits thyroid-stimulating hormone-induced morphological changes and induces the expression of major histocompatibility complex class II antigen in thyroid follicles in suspension culture.

The effects of interferon-gamma (IFN gamma) on the morphology of thyroid follicles and the expression of major histocompatibility complex (MHC) class II antigens were examined. The thyroid follicles were suspended in RPMI-1640 containing 10% fetal calf serum with or without IFN gamma (200 U/ml). After culture for 5 days, follicles were incubated in the presence of TSH (10 mU/ml) for 1 h and fixed for electron microscopic and immunohistochemical examination. Regardless of the presence of IFN gamma, suspended follicles became inverted within 5 days. However, MHC class II antigens were expressed only in inverted follicles cultured with IFN gamma. In inverted follicles cultured without IFN gamma, TSH stimulation induced remarkable morphological changes, such as elongation of microvilli and an appearance of pseudopods. On the other hand, the follicles cultured with IFN gamma showed poor response to TSH. Thus, IFN gamma induced the expression of MHC class II antigens of cultured thyroid follicles and inhibited TSH-induced morphological changes in the cells.

Animals↗