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Biomedical subjects

K Hashiba

Publications and source records attributed to K Hashiba.

At least 73 records · Page 4Linked to original sources
PubMed1990

Influences of autonomic changes on the sinus node recovery time in patients with sick sinus syndrome.

To assess the relative contribution of sympathetic and vagal influences on diurnal variation of sinus node recovery time (SNRT) in sick sinus syndrome (SSS), the diurnal changes of SNRT and the effects of propranolol and subsequent atropine on SNRT were examined in 39 patients with SSS. SNRT was measured before and after intravenous propranolol (0.1 mg/kg), and after subsequent intravenous atropine (0.02 mg/kg) in the cardiac catheterization laboratory. After completion of the electrophysiologic studies in the laboratory, SNRT was measured at 0 a.m. (midnight), 6 a.m. and 12 noon on the following day in the ward. After propranolol, SNRT was prolonged in 22 of 26 patients and shortened in 4 patients. After subsequent atropine, SNRT was prolonged in 5 of 26 patients and shortened in 21 patients. The patients with SNRT longer than 3 sec had a tendency to have greater diurnal variation of SNRT than those with SNRT less than 3 sec. A strong correlation (r = 0.98) was found between SNRT after propranolol and the longest SNRT in a 24-hour period. A difference of SNRT between after propranolol and after subsequent atropine was significantly correlated (r = 0.88) with a difference between the longest and the shortest SNRT in a 24-hour period. These results suggest that the diurnal changes in SNRT are regulated by the autonomic nervous system in SSS. SNRT after propranolol may be useful in estimating the longest SNRT in a day.

Adult↗
PubMed1990

[The relationship of osteoporosis to mitral annular and aortic valvular calcification in elderly women].

Mitral annular calcification (MAC) and aortic valve calcification (AVC) are thought to be attributable to the aging process, and their incidences are especially high in elderly women. It is known that the incidence of osteoporosis (OP) is also relatively high in elderly women. Therefore, we investigated the relationship of OP to MAC and AVC. The study subjects were 39 women aged 70-89 years. MAC and AVC were investigated by echocardiography. The amount of bone mineral (BM) in the lumbar vertebral bone was measured by computed tomography using a bone phantom and the standard amount of CaCO3. MAC and AVC were detected in 14 (35.9%) and 19 (48.7%) of the 39 subjects, respectively, and there was a tendency of coexistence of MAC and AVC. There was no significant age difference between patients with and without MAC. The amount of BM was significantly lower in patients with MAC than in patients without it (27.1 +/- 8.2 vs 53.5 +/- 27.3 mg/cm3: p less than 0.01). There was no correlation between the amounts of BM and AVC. In conclusion, the amount of BM is clearly lower in elderly women with MAC, suggesting that MAC may be related to OP etiologically. However, there was no clear relationship between AVC and OP. Thus, the etiologies of AVC and MAC may be different.

Aged↗
PubMed1990

[Paradoxical response of blood pressure to salt loading in renovascular hypertension].

We studied the effect of high salt intake on blood pressure in two cases with renovascular hypertension. They had hypertension with hyperreninemia and marked difference in plasma renin activity between both renal veins. Blood pressure significantly decreased after single oral administration of captopril. Renal arteriogram revealed significant stenosis in the main artery to the left (case 1) and right (case 2) kidney. Blood pressure response was evaluated after seven (case 1) and five (case 2) days of low salt and seven days (both cases) of high salt intake. Mean blood pressure in two patients was significantly decreased (case 1; 118 +/- 5.5 to 108 +/- 6.1 mmHg and case 2; 150 +/- 3.8 to 138 +/- 3.1 mmHg). Plasma renin activity was also decreased (case 1; 6.25 to 0.77 ng/ml/hr and case 2; 22.8 to 6.3 ng/ml/hr). In case 2, blood pressure elevated markedly during low salt intake, compared with blood pressure level during normal salt intake. The results suggest that excessive salt intake in patients with unilateral renovascular hypertension produces blood pressure reduction because of suppression of renin-angiotensin system. We concluded that in patients with unilateral renovascular hypertension dietary sodium depletion may be harmful, whereas salt supplement may have a beneficial effect.

Adult↗
PubMed1989

Electrophysiologic properties of atrial muscle in paroxysmal atrial fibrillation.

The electrophysiologic properties of atrial muscle were studied by programmed atrial stimulation in 42 patients with paroxysmal atrial fibrillation (PAF) and in 53 control patients without PAF. Single premature atrial stimulation was given at the right atrial appendage following 8 basic stimuli with a basic cycle length of 500 ms. Repetitive atrial firing (RAF) was defined as the occurrence of 2 or more successive premature atrial activations following single premature atrial stimulation. Fragmented atrial activity (FAA) was defined as an increase by more than 75% of the duration of the atrial electrogram in response to a single premature stimulation. Interatrial conduction delay was defined as an increase of the conduction time by more than 50 ms in response to a single premature stimulation. RAF was induced in 26 of 42 patients (61.9%) with PAF and in 14 of 53 control patients (26.4%). FAA and interatrial conduction delay were elicited in 69.0 and 80.9% of patients with PAF and in 34.0 and 56.6% of control patients, respectively. In 16 patients with PAF in whom RAF was not induced, FAA developed in 11 patients (68.8%). In 88.1% of 42 patients with PAF and in 41.5% of 53 controls, RAF or FAA, or both, were elicited by atrial premature stimulation. It is concluded that the incidence of RAF and FAA were significantly higher in patients with PAF than in the control group, and the induction of RAF or FAA, or both, was closely related to the vulnerability of the atrial muscle to atrial fibrillation.

Atrial Fibrillation↗
PubMed1989

Deletion of a phenylalanine in the N-terminal region of human cytochrome P-450(17 alpha) results in partial combined 17 alpha-hydroxylase/17,20-lyase deficiency.

Steroid 17 alpha-hydroxylase and 17,20-lyase activities reside within the same polypeptide chain (cytochrome P-450(17 alpha)), and consequently human 17 alpha-hydroxylase deficiencies are characterized by defects in either or both of these activities. Human mutants having these deficiencies represent an excellent source of material for investigation of P-450(17 alpha) structure-function relationships. The CYP17 gene from an individual having partial combined 17 alpha-hydroxylase/17,20-lyase deficiency has been characterized structurally and the homozygous mutation found to be the deletion of the phenylalanine codon (TTC) at either amino acid position 53 or 54 in exon 1. Reconstruction of this mutation into a human P-450(17 alpha) cDNA followed by expression in COS 1 cells led to production of the same amount of immunodetectable P-450(17 alpha) protein as found with expression of the normal human P-450(17 alpha) cDNA. However, 17 alpha-hydroxylase activity of this mutant protein measured in intact cells was less than 37% of that observed upon expression of the wild-type enzyme, whereas 17,20-lyase activity of the mutant was less than 8% of that observed with the normal enzyme. When estimated in intact cells, the Km for 17 alpha-hydroxylation of progesterone was increased by a factor of 2 in the mutant enzyme, whereas the Vmax was reduced by a factor of 3. In order to estimate the kinetic parameters for the 17,20-lyase reaction, microsomes were isolated from transfected COS 1 cells to enrich for this activity. Surprisingly, the specific activity of the mutant 17 alpha-hydroxylase in microsomes was 3-fold less than that observed in intact cells, indicating that the structure of mutant P-450(17 alpha) was dramatically altered upon disruption of COS 1 cells. Apparently the deletion of a single phenylalanine in the N-terminal region of P-450(17 alpha) alters its folding in such a way that both enzymatic activities are dramatically decreased, leading to the partial combined deficiency observed in this individual.

Adrenal Hyperplasia, Congenital↗
PubMed1989

Prorenin is sorted into the regulated secretory pathway independent of its processing to renin in mouse pituitary AtT-20 cells.

A native human prorenin and a mutant of its processing site (Arg-43 to Gln) were expressed in mouse pituitary AtT-20 cells which process prorenin to renin and have both regulated and constitutive secretory pathways. The native prorenin was processed to renin and secreted in a regulated manner. Although the mutant precursor was not processed, it was also secreted in a regulated manner. These results suggest that prorenin is sorted into the regulated pathway, stored in secretory granules and released by stimulus whether it is processed to renin or not.

Amino Acid Sequence↗
PubMed1989

Specific 125I-endothelin-1 binding sites in the atrioventricular node of the porcine heart.

The quantitative receptor autoradiographic method we used revealed that specific 125I-endothelin-1 binding sites are highly concentrated in the atrioventricular node of the porcine heart. 125I-Endothelin-1 binding to the atrioventricular node, interatrial and interventricular septa was displaced by unlabeled endothelin-1 with Kd values of 53 pM, 2.03 nM and 3.48 nM, respectively. Knowledge of the existence of specific 125I-endothelin-1 binding sites in the porcine heart helps with understanding the physiology of endothelin, a possible endogenous Ca2+ channel agonist.

Animals↗
PubMed1989

Tissue distribution and characterization of prorenin-converting enzyme in mouse.

Renin is produced from an inactive precursor, prorenin, through endoproteolytic cleavage at paired basic amino-acid residues. Using (35S)methionine-labeled prorenin, that was synthesized with Xenopus oocyte expression system, as a substrate, we have determined the tissue distribution and the nature of prorenin-converting activity in mouse. The highest activity was found in the submandibular gland of male ICR mouse. The activity of the enzyme seemed to be parallel to that of renin. This enzyme activity, with an optimal pH 8.0-8.5, was inhibited by leupeptin, antipain and benzamidine.

Animals↗
PubMed1989

Central effect of aprotinin, a serine protease inhibitor, on blood pressure in spontaneously hypertensive and Wistar-Kyoto rats.

We examined the effect of centrally administered aprotinin, a serine protease inhibitor, on blood pressure (BP) in conscious spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY). Twenty-two gauge needles and polyethylene catheters were implanted into lateral cerebroventricle and femoral artery, respectively, at 48 hours before the experiments. In Group 1 (8 SHR, 6 WKY), rats received a bolus intracerebroventricular injection (i.c.v.) of aprotinin (1,000 KIU/kg/10 microliters). A prompt increase of BP was observed in SHR after aprotinin and this elevation of BP was persisted for over 30 minutes (mean BP: 158.8 +/- 2.9 mmHg at control to 168.7 +/- 3.2 at 15 min., p less than 0.01; to 168.3 +/- 3.4 at 30 min., p less than 0.01). On the other hand, BP of WKY decreased gradually after aprotinin (mean BP: 143.0 +/- 3.3 at control to 136.8 +/- 2.7 at 15 min., n.s.; to 134.2 +/- 5.1 at 30 min., p less than 0.05). The intravenous injection (i.v.) of aprotinin (Group 2: 7 SHR, 5 WKY) and the i.c.v. of artificial cerebrospinal fluid (CSF) (Group 3: 5 SHR, 6 WKY) did not affect BP in both SHR and WKY except for the minor transient increase of BP in WKY immediately after artificial CSF i.c.v.. We performed additional experiments to study the contributions of sympathetic nervous system and vasopressin to these changes in BP.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Changes in T wave morphology during hypercalcemia and its relation to the severity of hypercalcemia.

The effect of hypercalcemia on T wave morphology, polarity, and amplitude was studied in 14 patients with a primary diagnosis of malignant lymphoma (8 patients), adult T-cell leukemia (5 patients), and Hodgkin's disease (1 patient). Hypercalcemia was severe to extreme in 11 (14.9-22.8 mg/dl), moderate in 1 (13.4 mg/dl), and mild in 2 (11.8 and 12.2 mg/dl) patients. Ten of the 11 patients (91%) with severe hypercalcemia showed inverted, biphasic, and notched T waves, mainly in the chest leads. Notched T waves were observed in all 10 of these patients in anterior to lateral, mid to lateral, or lateral chest leads. Biphasic and/or inverted T waves in anterior or anterior to midchest leads were present in 4 of these 10 patients who had extreme hypercalcemia (greater than 16 mg/dl). Changes in T wave morphology were not observed in moderate or mild hypercalcemia. T wave amplitude showed significant inverse correlation with serum calcium (T mV vs Ca, r = -0.60, p less than 0.001; T/R ratio vs Ca, r = -0.68, p less than 0.001; n = 35). Decrease in T wave amplitude was marked in severe hypercalcemia (p less than 0.0001) and moderate hypercalcemia, but there was no change in mild hypercalcemia. Changes in T wave morphology, polarity, and amplitude either appeared with development of hypercalcemia or disappeared with normalization of serum calcium level. It was concluded that in addition to shortening the QT interval, severe to extreme hypercalcemia can cause development of inverted, biphasic, or notched T wave with a marked decrease in amplitude of T waves.

Adult↗
PubMed1989

Effects of blood pressure changes on development and regression of electrocardiographic left ventricular hypertrophy: a 26 year longitudinal study.

At the Radiation Effects Research Foundation, medical examinations have been conducted biennially since 1958 on a fixed population of approximately 20,000 individuals. Blood pressure measurements and electrocardiographic (ECG) recordings are available for 6,569 individuals who were monitored for at least 11 of the 13 2 year intervals between 1958 and 1984. Data from 601 individuals who had satisfied the Foundation's ECG diagnostic criteria of left ventricular hypertrophy ("Kagan-Yano code") on at least one occasion were reviewed. Both the development and the regression of ECG left ventricular hypertrophy were ascertained in 61 subjects (17 men and 44 women). During the course of development of ECG left ventricular hypertrophy, hypertension (including borderline cases) was noted in 83.3% of the subjects. The most common pattern of ECG left ventricular hypertrophy development was high voltage, followed by ST-T changes. In about half of these cases, the condition of hypertrophy regression was associated with lowering of blood pressure, marked by the disappearance of high voltage ECG readings.

Blood Pressure↗
PubMed1989

Simultaneous monitoring of electrocardiogram and arterial blood pressure during exercise-induced syncope in a patient with severe aortic stenosis--a case report.

A sixty-six-year-old man with severe aortic stenosis, in whom simultaneous and continuous monitoring of the electrocardiogram and arterial blood pressure was performed immediately before, during, and following recovery from exercise-induced syncope, is reported. During exercise the patient developed anginal pain associated with a gradual fall of arterial blood pressure followed by syncope. At the onset of the syncope, arterial blood pressure was extremely low, and the electrocardiogram showed sinus tachycardia. It was assumed from these findings that profound hypotension, induced by peripheral vasodilatation and ischemic myocardial depression leading to inappropriately low cardiac output, was the underlying factor mainly responsible for the occurrence of exercise-induced syncope in the present case.

Aged↗
PubMed1989

Intra-atrial conduction delay and fragmented atrial activity in patients with paroxysmal atrial fibrillation.

To examine the electrophysiologic characteristics of paroxysmal atrial fibrillation (PAF), we studied intra-atrial conduction delay and fragmented atrial activity during premature stimulation of high right atrium in the following four groups: Group I (n = 25), patients without PAF and without sick sinus syndrome (SSS); Group II (n = 22), patients with PAF but without SSS; Group III (n = 10), patients without PAF and with SSS; Group IV (n = 6), patients with PAF and SSS. Intra-atrial conduction delay was the increase in the interval (from the stimuli to the coronary sinus electrogram) observed with early premature beats greater than or equal to 20 ms compared with that of basic rhythm. Fragmented atrial activity was defined as disorganized atrial activity greater than or equal to 150% of the duration of high atrial activity of basic beats recorded. The conduction delay zone (CDZ) and fragmented atrial activity zone (FAZ) were significantly wider in Groups II, III and IV than in Group I. There were no significant differences in either CDZs or FAZs among Groups II, III and IV. Thus, the widening of CDZs and/or FAZs are characteristic of PAF and SSS. CDZ and FAZ may be good indices of development of PAF in patients without SSS.

Adolescent↗
PubMed1989

Effects of chronic hypokalemia on ventricular vulnerability during acute myocardial ischemia in the dog.

Chronic hypokalemia (2.9 +/- 0.2 mEq/L) was induced in 10 dogs by a low potassium diet and furosemide administration. Five control dogs with normokalemia (5.0 +/- 0.3 mEq/L) were fed an ordinary diet. Three of the 10 hypokalemic dogs had electrically induced, nonsustained ventricular tachycardia (NSVT) and ventricular fibrillation (VF); none of the 5 control dogs had these ventricular arrhythmias. After ligation of the left anterior descending coronary artery (LAD), 4 of the 10 hypokalemic dogs developed spontaneous VF and 6 had electrically induced NSVT and VF, whereas 2 of the 5 control dogs had only NSVT. The effective refractory period (ERP) of the ventricles of the hypokalemic dogs was slightly longer than that of the control dogs. After LAD ligation, only the ERP of the anterior wall of the left ventricle was prolonged significantly in either group (p less than 0.01). The ventricular fibrillation threshold (VFT) of hypokalemic dogs was significantly lower than the control dogs (p less than 0.05), and was reduced markedly (p less than 0.05) after LAD ligation. A positive correlation between VFT and serum potassium level was observed. Thus, chronic hypokalemia increases ventricular vulnerability. This effect depends upon the severity of hypokalemia and is markedly augmented by acute myocardial ischemia. These findings indicate that, in clinical settings, preexisting hypokalemia and its severity may play important roles in the occurrence of lethal ventricular arrhythmias during the acute phase of myocardial infarction.

Acute Disease↗
PubMed1989

[Arrhythmias in the elderly].

Longitudinal Cohort Study: Electrocardiogram and blood pressure were taken biannually along with history taking, physical examination and other laboratory studies. 6,690 subjects were included in this study in whom at least 7 out of 9 biannual check up examinations were performed. At the end of the study period, their ages ranged from about 40 to 90 years. The incidence of atrial fibrillation was about 0.2% in the forties and early fifties and increased to 0.6% by the late fifties. The incidence of atrial fibrillation was then increased almost linearly up to 2.5% at the end of the eighties. Likewise, incidence of CRBBB and LBBB was also increased with age even after the age of sixty; 1.0% at the fifties to 7.5% at the eighties in CRBBB and 0.05% at the fifties to 1.4% at the eighties in LBBB, respectively. Holter ECG Study: Holter ECG was recorded in 164 healthy subjects aged 14 to 87 years in whom no arrhythmias were found in the routine 12 leads ECG at entry to the study. In 96.9% of the subjects APC was recorded in the 24-hour Holter ECG irrespective of their age. The total number of APCs in 24 hours significantly increased with age, especially after age sixty. The incidence of couplet or short run APCs was 21.4% under age sixty and 74.2% above age sixty. Electrophysiologic Studies in Patients with Paroxysmal Atrial Fibrillation (Paf): Repetitive atrial firing (RAF) elicited by premature atrial stimulation, and prolonged intra-atrial electrogram (PAE) with multiple (more than 7) spikes recorded during sinus rhythm were taken as indicators of atrial vulnerability. RAF and PAE was observed in more than 60% of Paf patients with or without sick sinus syndrome (SSS), but only approximately 25% in the control group (without SSS). It was also noted that in patients with SSS, who were generally of old age, RAF was observed in about 63% even without Paf. These results suggest that the atrial vulnerability might be an expression of the common electrophysiologic properties of the atrial muscle in the elderly with atrial arrhythmias and/or SSS. Syncopal Episodes due to Transient Severe Hyperkalemia in the Elderly: Two patients with mild to moderate chronic renal failure developed transient severe hyperkalemia (9.9, 7.3 mEq/L, respectively), severe sinus bradycardia with sinus arrest and syncopal episodes. These transient findings almost completely improved in a few days by kayexatete and bicarbonate, and temporary back-up atrial pacing. Hyperkalemia was disproportionately severe compared to BUN and serum creatinine.(ABSTRACT TRUNCATED AT 400 WORDS)

Age Factors↗
PubMed1989

UH series of monoclonal antibodies recognizing major histocompatibility complex class II antigen(s) of Japanese monkeys (Macaca fuscata).

Six mouse monoclonal antibodies were developed by immunization with a Japanese monkey cell line. These monoclonal antibodies, designated the UH series, reacted with large populations of peripheral B cells and monocytes, but not with T cells. The distribution of reactivities and the molecular weight of the membrane antigens recognized were similar to those of the HLA-DR monoclonal antibody; one inhibited the binding of HLA-DR. Human interferon-gamma induced increased expressions of all the UH antigen epitopes.

Animals↗