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Biomedical subjects

F Saito

Publications and source records attributed to F Saito.

At least 91 records · Page 5Linked to original sources
PubMed1993

Potential role of 12 hydroxyeicosatetraenoic acid in angiotensin II-induced calcium signal in rat glomerulosa cells.

Recent evidence suggests that 12 hydroxyeicosatetraenoic acid (12HETE), a product of the 12 lipoxygenase (LO) pathway of arachidonic acid metabolism, may have a role in mediating angiotensin II (AII)-induced aldosterone secretion. The present study examined the possible role of the 12 LO product 12HETE in AII-induced calcium ([Ca++]i) signals in rat glomerulosa cells. The addition of 12HETE to glomerulosa cells induced a dose-dependent (10(-6)-10(-8) M) rise in [Ca++]i levels that was sustained over 15 min. The effects of 12HETE on [Ca++]i were attenuated but not blocked by nifedipine (5 x 10(-6) M) and were preserved in a calcium-free medium, suggesting mobilization of intracellular calcium stores. Furthermore, the 12HETE-mediated rise in [Ca++]i was almost entirely abolished by dantrolene. In parallel, 12HETE reversed the inhibitory effect of nifedipine on AII-induced aldosterone secretion [AII (10(-9) M) - 36 +/- 7, AII + nifedipine (5 x 10(-6) M) - 13 +/- 2, AII + nifedipine + 12HETE (5 x 10(-8) M) - 27 +/- 4 ng/10(6) cells]. Dantrolene also inhibited AII-dependent aldosterone secretion (AII 10(-9) M - 75.8 +/- 5.6, AII + dantrolene 10(-6) M 45.5 +/- 8.8 ng/10(-6) cells), but this inhibition could not be reversed by 12HETE 10(-8) M (45.4 +/- 10.6 ng/10(6) cells). The LO blockers baicalein and BW755C inhibited the effect of AII on aldosterone production and on [Ca++]i in a parallel fashion. During LO blockade, the addition of 12HETE (10(-7) M) restored the AII-induced rise in [Ca++]i. Collectively, these observations suggest that activation of the LO pathway in the rat adrenal glomerulosa contributes to change in cytosolic calcium, which may be important for the steroidogenic effect of AII.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1993

Studies of HIV-1 protease inhibitors. II. Incorporation of four types of hydroxyethylene dipeptide isosteres at the scissile site of substrate sequences.

Human immunodeficiency virus type 1 (HIV-1) protease inhibitors containing four types of hydroxyethylene dipeptide isosteres were designed and synthesized. These inhibitors consist of eight stereoisomers of phenylalanylproline (Phe-psi[H.E.]-Pro), four stereoisomers of phenylalanylalanine [Phe-psi[H.E.]-Ala), and one stereoisomer each of phenylalanylglycine (Phe-psi[H.E.]-Gly) and cyclohexylalanylalanine (Cha-psi[H.E.]-Ala) hydroxyethylene dipeptide isosteres. For the synthesis of the latter two isosteres, a newly developed synthetic method for gamma-lactone was applied. The inhibitory activities of these peptides were evaluated by cleavage assay of partially purified gag proteins or purified synthetic peptide. Of the inhibitors examined, compounds 2c (Z-Asn-(2S,3R,4S,5S)-Phe-psi[H.E.]-Pro-NHB(un); Bu(n) = n-butyl, Ki = 0.50 microM), 21a (Z-Asn-(2R,4S,5S)-Phe-psi[H.E.]-Ala- NHBu(n), Ki = 0.34 microM) and 23 (Z-Asn-(2R,4S,5S)-Cha-psi[H.E.]-Ala- NHBu(n), Ki = 0.46 microM) were moderately potent inhibitors. The results revealed that the alkyl substituent at C2 is essential, and the stereochemistry of the hydroxyethylene dipeptide isosteres greatly affected their inhibitory activities.

Amino Acid Sequence↗
PubMed1993

[A study on the prediction of long-term prognosis of adulthood epilepsy].

We report results of a study on the relation between the clinical findings 2 years after initiation of the therapy and the long-term prognosis of seizure control, and discuss the possibility of predicting the prognosis in the early stage of therapy. The subjects consisted of 141 patients, observed for 10 to 20 years at Hirosaki University Hospital. Regarding the epilepsy type, the prognosis of temporal lobe epilepsy was unfavorable. In temporal lobe epilepsy, only 21% were in remission (seizure-free for 3 years or more) at the time of the study. Also, the presence of organic brain lesions or neuropsychiatric complications at the early stage of treatment was associated with unfavorable prognosis. We are particularly interested in the possibility of predicting the long-term prognosis from the result of early response to anti-epileptic drug therapy. We found a significant correlation between the early excellent response to drug treatment and the good long-term prognosis. Using discriminant analysis (quantification theory II), we tried to find which factors would influence more to the long-term prognosis. As the result, an importance was found in the following order: (1) epilepsy type, (2) presence or absence of neuropsychiatric complications, (3) age at onset, (4) early response to treatment, (5) presence or absence of organic brain lesions and (6) the interval between the onset and the initiation of drug treatment. Correct identification rate by discriminant analysis was 73%.

Adolescent↗
PubMed1992

Synthesis and biological action of the aminotetrahydroisoquinocarbazoles and related compounds: a new class of compounds with antiarrhythmic activity.

A series of 12-aminotetrahydroisoquinocarbazoles and related compounds were synthesized using an intramolecular Diels-Alder reaction and screened for antiarrhythmic activity in chloroform-induced ventricular arrhythmias in mice. Several compounds showed more potent activity than disopyramide. There was some correlation between substituents on aromatic ring and angular position, and antiarrhythmic activity. An amino group or some functional groups containing an amino group on C-12 seemed to be essential to exhibit the activity. Ring size also influenced the activity. The compound (+)-10 (RS-2135) had the most favorable combination of antiarrhythmic activity and toxicity and was selected for further evaluation.

Action Potentials↗
PubMed1992

Histochemical study of pituitary adenomas with Ki-67 and anti-DNA polymerase alpha monoclonal antibodies, bromodeoxyuridine labeling, and nucleolar organizer region counts.

The growth potential of 65 pituitary adenomas was determined by histochemical analysis with Ki-67 and anti-DNA polymerase alpha monoclonal antibodies, bromodeoxyuridine (BrdUdR) labeling, and counts of argyrophilic nucleolar organizer regions (Ag-NORs). The mean proliferating cell indices (PCIs) determined by Ki-67 and anti-DNA polymerase alpha and the BrdUdR labeling index (LI) were generally very low [1.0 +/- 0.2%, 1.1 +/- 0.2%, and 0.5 +/- 0.1% (+/- SE), respectively]. Apart from adrenocorticotropic hormone-positive adenomas, which had significantly higher indices, there were no statistically significant differences in the indices among the other subtypes of pituitary adenomas. Recurrent tumors had higher Ki-67 and DNA polymerase alpha PCIs and BrdUdR LIs (3.6%, 4.2%, 1.4%) than primary tumors (0.8%, 0.8%, 0.3%; P less than 0.005). The number of Ag-NORs did not correlate significantly with any of the three indices. The mean number of Ag-NORs was higher in nonfunctioning adenomas than in functioning adenomas (2.04 vs 1.66, P less than 0.005); among prolactin-positive adenomas, those treated preoperatively with bromocriptine had more Ag-NORs than untreated tumors (1.75 vs 1.57, P less than 0.005). These results suggest that the Ki-67 and DNA polymerase alpha PCIs and the BrdUdR LI predict the growth potential of individual pituitary adenomas, whereas the number of Ag-NORs appears to correlate with hormone production rather than with the proliferative potential.

Adenoma↗
PubMed1992

12-Lipoxygenase products modulate calcium signals in vascular smooth muscle cells.

Previous studies have shown that inhibition of the lipoxygenase pathway of arachidonic acid metabolism can prevent the development of elevated blood pressure in renin-dependent models of hypertension. Agents that inhibit the lipoxygenase pathway such as phenidone and the flavonoid baicalein can selectively attenuate contractile responses to angiotensin II in vivo as well as in isolated vascular tissue. In the present study, the effects of lipoxygenase inhibitors on pressor-induced changes in cytosolic calcium were examined in cultured rat vascular smooth muscle cells using the fluorescent dye fura-2. Two structurally unrelated lipoxygenase inhibitors, baicalein and 5,8,11-eicosatriynoic acid, attenuated angiotensin II-stimulated increases in cytosolic calcium in both normal and calcium-poor buffer. The addition of 5-, 12-, or 15(S)-hydroxyeicosatetraenoic acid alone to the cells had no acute effect on intracellular calcium concentration. However, the addition of 12(S)-hydroxyeicosatetraenoic acid but not 5- or 15(S)-hydroxyeicosatetraenoic acid restored the initial calcium response to angiotensin II in vascular smooth muscle cells pretreated with both inhibitors; 5,8,11-eicosatriynoic acid also reduced [Arg8]-vasopressin and endothelin-stimulated increases in intracellular calcium. The attenuation of vasopressor-induced calcium transients by agents that inhibit lipoxygenase may explain their observed hypotensive effects in vivo. Moreover, lipoxygenase products, in particular 12(S)-hydroxyeicosatetraenoic acid, may act as mediators for the intracellular actions of angiotensin II and possibly other pressor hormones in vascular tissue by regulation of intracellular calcium metabolism.

Angiotensin II↗
PubMed1992

Blood pressure response to hyperinsulinemia in salt-sensitive and salt-resistant rats.

We investigated the role of insulin in salt-sensitive hypertension in Dahl salt-sensitive and salt-resistant rats. The rats were kept in metabolic cages, and sodium intake and urinary sodium excretion were measured. In salt-sensitive rats receiving a 0.3% NaCl diet, sodium retention was significantly greater at weeks 1 and 2 in rats that received an insulin infusion than in those receiving a saline infusion. Mean arterial blood pressure and plasma norepinephrine levels were significantly higher at week 3 in insulin-treated rats than in saline-treated rats (mean arterial pressure, 137 +/- 3 mm Hg versus 119 +/- 3 mm Hg, p < 0.05; plasma norepinephrine, 0.40 +/- 0.02 ng/ml versus 0.27 +/- 0.01 ng/ml, p < 0.05). Insulin did not influence sodium retention, mean arterial pressure, or plasma norepinephrine in salt-resistant rats. Coadministration of an alpha-blocker (bunazosin, 10 mg/kg per day for 3 weeks) in salt-sensitive rats abolished the insulin-induced elevations in mean arterial pressure and sodium retention. When salt-sensitive rats were fed a low salt diet (0.03% NaCl), insulin did not raise mean arterial pressure. Thus, insulin elevated blood pressure only in the salt-sensitive model. The sympathetic nervous system and sodium retention in the early phase of insulin overload may contribute to elevation of mean arterial pressure in this model.

Animals↗
PubMed1992

[An autopsied case of Parkinson's disease manifesting Shy-Drager syndrome].

We report an autopsied case of Parkinson's disease manifesting Shy-Drager syndrome. At the age of 63 years, the patient noticed an onset of progressive orthostatic dizziness, which was followed by constipation, dysuria, and sexual impotence. When he was 66 years old, syncopal attack for a few minutes, tremor in the bilateral hands, and memory disturbance developed. On admission, his blood pressure was 142/72 mmHg in supine position, which fell to 58/42 mmHg on standing with appropriate increase of heart rate. Neurological examination revealed hallucination, memory disturbance, masked face, muscular rigidity, bradykinesia, mild postural tremor, and autonomic dysfunction including severe orthostatic hypotension, hypohydrosis, constipation, dysuria, and sexual impotence. Electroencephalogram showed diffuse slowing. Brain CT demonstrated absence of severe atrophy of the cerebellum, and brain stem. Pharmacological study revealed denervation hypersensitivity to the intravenously administrated noradrenaline. A diagnosis of Shy-Drager syndrome was made, and he was treated with anti parkinsonian drugs. However, no improvement was observed in his clinical symptoms. Seven months later, he died of pneumonia. Neuropathological examination revealed marked neuronal cell loss and gliosis in the substantia nigra and locus ceruleus. Lewy bodies were seen in those pigmented nuclei, dorsal vagal nucleus, hypothalamus and nucleus basalis of Meynert. No abnormality was found in the intermediolateral nucleus of the spinal cord. This is the first report on a Japanese patient who presented clinically Shy-Drager syndrome and pathologically typical Parkinson's disease. In this patient, from the pharmacological and pathological findings, sympathetic ganglia were supposed to be the responsible lesion for orthostatic hypotension.

Aged↗
PubMed1991

The nucleotide sequence for a proline-activating domain of gramicidin S synthetase 2 gene from Bacillus brevis.

A fragment encoding proline-activating domain (grs 2-pro) of gramicidin S synthetase 2 (GS 2) was found in an 8.1-kilobase pairs (kb) DNA fragment of Bacillus brevis Nagano, which contained the full length of GS 1 gene (grs 1). The clones designated GS719 and GS708, which expressed gramicidin S synthetase 1, were elucidated to express immunoreactive proteins to GS 2 antibodies with approximate molecular weights of 115,000, 105,000 (GS719), and 110,000 (GS708). The partial purification of the gene products of these clones was carried out using DEAE-Sepharose CL-6B column chromatography. The immunoreactive proteins to GS 2 antibodies were separated from gramicidin S synthetase 1 protein and had specific proline-dependent ATP-32PPi exchange activity. The nucleotide sequence for the proline-activating domain in the 8.1-kb insert was determined. This fragment was 2,879 base pairs long, and encoded 959 amino acids. The calculated molecular weight of 111,671 was consistent with the apparent molecular weight of 115,000 found in SDS-PAGE of the immunoreactive products to GS 2 antibodies. The open reading frame for this protein followed grs 1 gene, though two were separated by a 73-base pair noncoding sequence, and remained open to the end.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Isomerases↗
PubMed1991

A study on driving status in 98 epileptic patients with driving licences.

As to the driving status in the period between January 1984 and December 1988, 98 epileptic patients with driving licences were examined, paying regard to their clinical conditions. Sixty-one (62%) of the patients were seizure-free for the last five years or more in December 1988. Eighty-one (83%) were actually driving motor vehicles at the time of this study, and 27 (33%) of the 81 drivers still had fits during the past five years. Nine patients (9%) had caused traffic accidents, but no accident had occurred due to seizures. The type of the nine accidents was as follows: One case of a slight physical injury to the other person, four cases of the driver's own car damage without other material damage, and four of the accidents involving other cars.

Accidents, Traffic↗
PubMed1991

[Serious complications of intravesical bacillus Calmette-Guerin therapy in patients with bladder cancer].

Side effects and serious complications of intravesical bacillus Calmette-Guérin (BCG) therapy were reviewed in 120 patients with transitional cell carcinoma of the urinary bladder from October, 1983 to June, 1989 at Hirosaki University Hospital. As local side effects, 102 patients (85.0%) had bladder irritability with frequency and/or micturition pain, and 46 patients (38.3%) had hematopyuria. As systemic side effects, fever in 43 patients (35.8%), elevation of serum GOT, GPT in 9 patients (7.5%), and malaise in 3 patients (2.5%) were seen. Serious complications were observed in 7 patients. 4 patients had a severely contracted bladder with decreased compliance less than 50 ml, 2 patients had persistent arthritis and one patient had interstitial pneumonia. In all 4 patients with a contracted bladder partial cystectomy was performed before or after intravesical BCG therapy, and three of them received more than ten times instillation of BCG. It was suggested that contracted bladder most likely occurred after frequent BCG instillations in addition to decreased bladder compliance. Contracted bladder was irreversible in 2 patients. Histopathologically, there was marked fibrosis in the muscular layer of the bladder without tuberculous inflammatory changes. It might depend on the severity of fibrosis in the muscular layer whether contracted bladder was reversible or not. Persistent arthritis was nonspecific inflammation with negative culture results for mycobacteria in the joint fluid in 2 patients. In one patient with interstitial pneumonia, fiberoptic bronchoscopy with transbronchial lung biopsy demonstrated marked fibrosis of alveolar septums and increased lymphocyte count without tuberculous inflammatory changes. The pathogenesis of this complications is considered to be a hypersensitivity reaction to BCG.

Administration, Intravesical↗
PubMed1991

[Mouse fetal brain specific protein "GP68" is expressed in human tumor cells].

It is well known that some fetal antigens are expressed in malignant tumor cells. Likewise, brain tumors, especially histologically malignant cases, may have any antigenic relationships with fetal brain. So, we investigated the relationship by immunohistochemical technique, utilizing a polyclonal antibody to mouse fetal stage-specific polypeptide "GP68". We prepared GP68 from homogenate of head part of embryos at the 14th day of gestation mice by RCA-1 agarose column chromatography. And immunized it to Japanese white rabbits and the titer was measured by enzyme-linked immunosorbent assay. We analyzed operatively resected brain tumors and autopsy brain tissues. Frozen tissues were fixed in cold acetone and immunostained with anti-GP68 serum according to biotin-streptavidin peroxidase method. Remained tissues were homogenized in Laemmli's sample buffer and electrophoresed. The proteins were transferred to nitrocellulose membrane and immunostained with anti-GP68. Normal brain tissues were not positively stained, except for capillary endothelium which showed a weak staining. On the other hand, brain tumors of neuroectodermal origin were positively stained in varying degrees, and other tumors were negative. It is especially noteworthy that, in astrocytoma cases, there exists a definite correlation between the intensity of stain and the degree of histological malignancy. Immunoblot studies demonstrated a very weak band at 68 KD in normal brain and meningioma. In contrast, very strong band at the same position was seen in malignant astrocytomas. These results suggested that in brain tumors, especially those of neuroectodermal origin, GP68 antigen is expressed and the degree of expression is related to their histological malignancy. So this fetal antigen may be useful for evaluation of biological malignancy of gliomas.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

[Glioblastoma of the cerebellum: report of an autopsy case associated with intratumoral hemorrhage and CSF seedings].

An autopsy case of glioblastoma of the cerebellum associated with an intracerebellar hemorrhage and showing CSF seedings is reported. A 26 year-old male was admitted to our hospital with a 10-day history of headache, nausea and vertigo. On admission, disturbance of consciousness (10-20 by JCS), irregular respiration and central fixation of both eyes suggesting increased intracranial pressure and early stage of central herniation were recognized clinically. The cerebellar signs of dysmetria and nystagmus were also observed. CT scan and angiography revealed an avascular large mass in the right cerebellar hemisphere, obstructive hydrocephalus and upward transtentorial herniation. On MRI study, the mass was demonstrated to be a subacute hematoma with a small tumor in its margin. Total removal of the tumor and aspiration of the hematoma were performed. Histological examination revealed a highly cellular and pleomorphic astrocytic tumor with scattered small necrosis and glomeruloid capillary endothelial proliferation, typical of glioblastoma multiforme. During postoperative radiochemotherapy (focal irradiation to the posterior fossa), the tumor showed rapid regrowth and a second look operation was performed. He was readmitted 3 weeks after radiochemotherapy with complaints of severe headache, nausea and lumbago. He then suddenly became dyspnea, tetraplegic and bradycardic. Neuroradiological investigation revealed multiple masses in the suprasellar region, medulla oblongata and the cervical spinal cord, but no recurrence in the cerebellum. Malignant cells were noted on CSF cytology. During chemotherapy for CSF tumor dissemination, his condition deteriorated rapidly and he died 7 months after the onset of symptoms.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Clinical significance of simple heart rate-adjusted ST segment depression in supine leg exercise in the diagnosis of coronary artery disease.

To evaluate the clinical significance of simple heart rate-adjusted ST segment depression (delta ST/delta HR) in the diagnosis of coronary artery disease, 42 patients with stable exertional angina underwent supine leg exercise testing and cardiac catheterization. During exercise, heart rate, a multilead electrocardiogram, and pulmonary artery wedge pressure were recorded. The sensitivity and accuracy of the delta ST/delta HR criteria (greater than or equal to 3.0 microV/beat/min) were significantly greater than the conventional analysis of ST segment depression criteria (greater than or equal to 0.2 mV) for detecting three-vessel coronary artery disease at a matched specificity of 72% (100% versus 46%, 81% versus 64%, p less than 0.01). A significant linear correlation was found between maximum pulmonary artery wedge pressure increments during exercise (delta PAWP) or Gensini score and the delta ST/delta HR (delta PAWP: r = 0.51, p less than 0.001; Gensini score: r = 0.47, p less than 0.001). There were no statistically significant differences in the delta PAWP or Gensini score between patients with three-vessel disease who had delta ST/delta HR greater than or equal to 3.0 microV/beat/min and those with one- or two-vessel disease who had delta ST/delta HR greater than or equal to 3.0 microV/beat/min (delta PAWP: 18.1 +/- 2.0 versus 21.9 +/- 3.3, p = NS; Gensini score: 68.5 +/- 6.6 versus 66.3 +/- 11.3, p = NS). These findings demonstrate that delta ST/delta HR is more useful than a conventional analysis of ST segment depression for identifying not only anatomically severe coronary artery disease but also functionally severe coronary artery disease.

Adult↗
PubMed1990

Prognostic value of abnormal postexercise systolic blood pressure response: prehospital discharge test after myocardial infarction in Japan.

To assess the prognostic value of an abnormal postexercise response in systolic blood pressure (SBP), treadmill exercise testing was performed in 217 survivors of acute myocardial infarction at an average of 9.3 weeks after infarction. During the mean follow-up period of 4 years, cardiac events were noted in 34 patients (16%), including cardiac death in 13 (6%), nonfatal reinfarction in 12 (6%), and coronary artery bypass graft surgery in nine (4%). An abnormal postexercise SBP response was defined as the ratio of SBP at 3 minutes of recovery to peak exercise SBP of 0.9 or more, on the basis of the cutoff point with the highest sensitivity and specificity to predict cardiac events. An abnormal postexercise SBP response occurred in 90 patients (42%). Patients with an abnormal postexercise SBP response had more exercise-induced myocardial ischemia. more left ventricular impairment, and more extensive coronary artery lesions than those without. Cox proportional hazards model demonstrated that the abnormal postexercise SBP response was ranked first in ability to predict cardiac death (p = 0.025, relative risk 15.41). Bypass surgery was associated with an abnormal postexercise SBP ratio (p less than 0.05). Nonfatal reinfarction could not be predicted by any clinical or exercise variables. In conclusion, an abnormal postexercise SBP response could be useful for predicting cardiac death and the need for bypass surgery after myocardial infarction. This response is probably the result of myocardial ischemia and left ventricular impairment.

Adult↗