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Biomedical subjects

I Abe

Publications and source records attributed to I Abe.

At least 163 records · Page 9Linked to original sources
PubMed1993

Renovascular hypertension caused by lymph node metastasis in a patient with uterine cervical cancer: case report.

Renovascular hypertension was found in a fifty-four-year-old woman who had been diagnosed as having uterine cervical cancer, stage Ib, six months before admission. Renal arteriography showed a stenosis of the right renal artery with a significant increase in renal vein renin level from the ipsilateral kidney. Abdominal computed tomographic scanning showed enlarged lymph nodes in the para-aortic region at the level of the right renal artery, which suggested metastasis of the carcinoma. Metastatic lymph node swellings probably caused compression of the right renal artery.

Female↗
PubMed1993

Invasive development of right atrial myxoma--a case report.

A thirty-nine-year-old man was admitted to the authors' department complaining of exertional dyspnea and high fever. An echocardiogram showed a mass in the right atrium, which was observed to move to the right atrium during the systolic phase and to the right ventricle during the diastolic phase. Magnetic resonance imaging showed that the mass developed from the right atrium to the superior vena cava. Intravenous digital subtraction angiography also showed a partial defect of the right atrium as well as obstructions of both the superior vena cava and the bilateral innominate veins. A pulmonary hemodynamic scintigram showed multiple defects at the mid and inferior areas of each lung, suggesting multiple pulmonary infarctions. The right atrial tumor was surgically removed. The superior vena cava and the innominate veins were found to be obstructed by organized thrombi, and the tumor had invasively grown into the right atrial wall. Histologic findings demonstrated that most of the tumor was composed of organized thrombi with scattered myxomatous tissue and was diagnosed as cardiac myxoma. These histologic findings suggest that the histogenesis of this right atrial myxoma might be thrombogenic.

Adult↗
PubMed1993

Arterial pressure and its regulation in rats bred successively on low sodium diet.

To investigate the effects of long-term sodium restriction on mechanisms regulating cardiovascular function, Wistar rats at weaning (F0) were placed on a normal (0.4%) or low (0.05%) sodium diet. The first (F1) and second (F2) generations were derived from inbreeding within each group. The resting mean arterial pressure did not differ between the diet groups of F0 or F1 rats, but it was significantly lower in F2 rats on the low sodium diet. Plasma renin concentration was similar in the two groups in each generation, and the F2 rats on both diets responded to [Sar1, Ala8] angiotensin II with the same degree of decrease in arterial pressure. Plasma norepinephrine was not influenced by sodium intake in the F0 or F1 rats, but was significantly lower in F2 rats on the low sodium diet. The depressor response to hexamethonium was similar in the two F1 groups, while low sodium F2 rats exhibited a lesser response. These results suggest that rats bred successively on a low sodium diet have a suppressed sympathetic nerve function with no enhancement of the renin-angiotensin system, which in turn results in a lower arterial pressure.

Animals↗
PubMed1993

[Evaluation of the localizing procedures of primary aldosteronism].

The validity of preoperative localizing procedures was studied in 36 patients with primary aldosteronism due to adrenal adenoma, all of whom were confirmed surgically. Adrenalectomy resulted in normalization of blood pressure and serum potassium. Furthermore, we reviewed the correlation between mass size and some clinical parameters as well as the accuracy of localization procedures. Adopted localization procedures included imaging techniques such as abdominal ultrasonography, computed tomography (CT), adrenal scintiscan, magnetic resonance imaging (MRI) and adrenal venography, and as a functional diagnostic procedure, adrenal venous sampling. Among imaging procedures, CT was the most effective to detect adrenal mass with as high accuracy as 88%, adrenal venography following with 83%. The correct localization was obtained in 60% by adrenal scintiscan and only 39% by ultrasonography. Although MRI was performed only in 2 cases, the smallest adenoma could be detected only by MRI, suggesting that MRI might be useful to detect microadenoma by increased signal intensity. Although adrenal scintiscan had been considered to be useful because of its functional diagnostic characteristics, the correct localization was as low accuracy as 60%, which was not improved by the administration of dexamethasone. To assess the accuracy of lateralization for adrenal venous sampling, we calculated the ratio of aldosterone concentration in adrenal vein to inferior vena cava. When the ratio was more than 10 or less than 1, the correct localization was made.(ABSTRACT TRUNCATED AT 250 WORDS)

Abdomen↗
PubMed1992

Affinity labeling of vertebrate oxidosqualene cyclases with a tritiated suicide substrate.

Pig and rat liver oxidosqualene cyclase (OSC) enzymes were purified to homogeneity and showed single bands on SDS-polyacrylamide gel electrophoresis with molecular masses of 75 kDa (pig) and 78 kDa (rat). Pig liver OSC was purified for the first time (441-fold with a yield of 39%). Chemical affinity labeling of pure or crude preparations of the liver cyclases using the mechanism-based irreversible inhibitor of OSC, [3H]29-methylidene-2,3-oxidosqualene ([3H]29-MOS), showed a single radioactive band at 75 kDa (pig) and 78 kDa (rat). Affinity labeling experiments were also performed with dog and human microsomal preparations and with yeast and plant cyclases. All of the vertebrate OSC enzymes were specifically labeled with [3H]29-MOS and gave a single band with molecular masses ranging from 70 to 80 kDa (rat, 78 kDa; dog, 73 kDa; pig, 75 kDa; and human, 73 kDa). In contrast, yeast lanosterol cyclase and plant cycloartenol cyclase were not labeled, demonstrating subtle differences in the active sites of animal, plant, and fungal enzymes.

Affinity Labels↗
PubMed1992

Comparison of effects of enalapril and captopril on serum potassium concentration in the treatment of malignant hypertension.

To compare the effects of enalapril and captopril on blood pressure, serum creatinine (S-Cr), and potassium (S-K) levels, patients with malignant hypertension treated with either 5-10 mg of enalapril (eight cases) or 75-400 mg of captopril (eight cases) were investigated retrospectively. After 2 weeks of treatment, the average blood pressure fell from 214/138 to 132/89 mmHg on enalapril and from 240/145 to 147/95 mmHg on captopril. The percent change in mean blood pressure during the 2 weeks of treatment with enalapril (-35.6 +/- 4.0 SE%) was similar to that with captopril (-35.8 +/- 2.8%). S-Cr did not change in both groups, while S-K increased significantly from 3.9 +/- 0.2 to 5.2 +/- 0.2 mEq/l on enalapril and from 3.6 +/- 0.2 to 4.2 +/- 0.1 mEq/l on captopril. S-K at the second week was significantly higher in the enalapril than in the captopril group. The maximum S-Cr concentration during the treatment was correlated with the corresponding S-K concentration similarly in both groups. These results indicate that both enalapril and captopril increase S-K without deterioration of renal function in patients with malignant hypertension and that the way these drugs are used in clinical practice may be more likely to result in elevated S-K with enalapril.

Adult↗
PubMed1992

Differential modulation by mu- and delta-opioids on baroreceptor reflex in conscious rabbits.

We examined the role of central mu- and delta-opioids on both neurohormonal responses and baroreceptor reflex in conscious rabbits. Both intracerebroventricular [D-Ala2,N-Me-Phe4,Gly5-ol]-enkephalin, a mu-selective agonist, and [D-Ala2,D-Leu5]-enkephalin, a delta-selective agonist, caused dose-related increases in arterial pressure and renal sympathetic nerve activity, whereas intravenous injection of the same maximum dose of these peptides as that used in the intracerebroventricular experiment did not cause any cardiovascular and neuronal responses. On the other hand, increases in plasma epinephrine, norepinephrine, and glucose levels induced by intracerebroventricular [D-Ala2,N-Me-Phe4,Gly5-ol]-enkephalin were significantly greater than those by [D-Ala2,D-Leu5]-enkephalin. Both enkephalins did not cause any responses in plasma renin activity, plasma vasopressin, and serum sodium and potassium concentrations. The sensitivity of the baroreceptor reflex control of renal sympathetic nerve activity using a logistic model was enhanced by a subpressor dose of intracerebroventricular [D-Ala2,N-Me-Phe4,Gly5-ol]-enkephalin (10 pmol/kg) but not by [D-Ala2,D-Leu5]-enkephalin. Conversely, a mu-selective dose of intravenous naloxone (0.1 mg/kg) attenuated baroreceptor reflex sensitivity. Intravenous naloxone methobromide, which has been shown not to cross the blood-brain barrier, did not change baroreceptor reflex sensitivity, suggesting that naloxone acts at the central nervous system. In conclusion, in conscious rabbits, 1) intracerebroventricular mu- and delta-receptor agonists caused pressor responses and 2) mu-opioid agonist altered baroreceptor reflex control of renal sympathetic nerve activity and produced changes in sympathoadrenal responses.

Animals↗
PubMed1991

Immobilized urokinase column as part of a specific detection system for plasminogen species separated by high-performance affinity chromatography.

Immobilized urokinase was used as part of a post-column reactor for the specific detection of human plasminogen species which were fractionated using a high-performance affinity column. After on-line activation of each peak, plasmin activity was measured by mixing the eluate with a specific fluorogenic substrate and the product was detected by a fluorescence monitor. This detection system gave linear calibration graphs for both purified plasminogens (0.1-50 micrograms) and plasminogens contained in plasma (25-100 microliters). Relative standard deviations for the determination of plasminogens in plasma were 6.1-6.6% (n = 12), showing good reproducibility. The detection limit was as low as 0.1 micrograms of plasminogen. Immobilized urokinase was very stable and no appreciable decrease in activity was found after 100 cycles of operation. In combination with an immobilized benzamidine column, this system made it possible to separate and detect Glu-plasminogen and Lys-plasminogen contained in human plasma samples as small as 100 microliters without any pretreatment.

Chromatography, Affinity↗
PubMed1991

Ambulatory blood pressure monitoring in elderly hypertensives treated with the new calcium antagonist, nilvadipine.

A newly developed calcium antagonist, nilvadipine, was administered to 7 hypertensive patients aged 75.6 y. Nilvadipine 4 mg b.d. decreased the average 24-h blood pressure significantly from 169/89 mmHg to 152/81 mmHg after 7 to 14 days without any change in the pulse rate. The circadian patterns of blood pressure and pulse rate were not affected by nilvadipine. Although the present study was a preliminary one done over a short period in a small number of patients, the results suggest that nilvadipine exerts an antihypertensive effect without altering the circadian pattern or the variability of blood pressure in elderly hypertensive patients.

Aged↗
PubMed1991

Lack of sympathetic augmentation in response to intravenous load of glucose in rabbits.

1. We investigated a link between sympathetic nervous function and carbohydrate metabolism by measuring renal sympathetic nerve activity in response to intravenous load of glucose in alpha-chloralose-urethane anaesthetized rabbits. 2. Intravenous infusion of a 25% glucose solution (0.5 g/kg) over 3 min caused a transient increase in arterial blood pressure and a decrease in renal sympathetic nerve activity. Thereafter, these parameters were restored and remained around preload levels while plasma glucose and insulin concentrations were still elevated. 3. Equimolar mannitol solution produced similar patterns of change in blood pressure and nerve activity without an elevation of plasma glucose and insulin levels. 4. The transient changes in blood pressure and renal nerve activity could be attributed to acute hypervolaemia indicated by similar changes in plasma osmolality and haematocrits in the two groups of treatment. 5. The present study did not support a close relationship between carbohydrate metabolism and the sympathetic nervous system regulating cardiovascular function.

Animals↗
PubMed1991

Central effect of endothelin on neurohormonal responses in conscious rabbits.

It has been shown that endothelin-1 (ET-1) binding sites exist in the central nervous system and that the injection of intracerebroventricular ET-1 induces a pressor response. Therefore, we determined the neurohormonal and cardiovascular responses to intracerebroventricular ET-1 (25 pmol/kg) in conscious rabbits with chronically instrumented electrodes on the renal sympathetic nerve. Intracerebroventricular ET-1 provoked a prompt increase in arterial pressure and in renal sympathetic nerve activity within 5 minutes, and peak values were obtained at 20 and 40 minutes, respectively. Plasma epinephrine and norepinephrine reached peak values at 5-20 minutes. Plasma vasopressin and plasma glucose levels also increased significantly, but plasma osmolality, hematocrit, and serum sodium and potassium concentrations did not show any changes. Arterial blood gas analysis showed respiratory alkalosis. However, pretreatment with intravenous pentolinium (5 mg/kg), a ganglion blocking agent, abolished these neurohormonal and cardiovascular responses. Conversely, the same dose of intravenous ET-1 (25 pmol/kg) as that used in the intracerebroventricular experiment failed to cause any cardiovascular or renal sympathetic nerve responses. These results suggest that intracerebroventricular ET-1 acts in the central nervous system and causes a pressor response mainly through the enhancement of sympathoadrenal outflow.

Animals↗
PubMed1991

Purification and some properties of squalene-2,3-epoxide: lanosterol cyclase from rat liver.

Squalene-2,3-epoxide: lanosterol cyclase was purified from rat liver in five steps as a soluble and homogeneous protein. The purified enzyme showed a single band on SDS-polyacrylamide gel electrophoresis with a molecular weight of 75 kD. In its native state it behaved as a homo-dimer. The isoelectric point of 5.5 and the apparent Km value for (3S)-squalene-epoxide of 55 microM were estimated for the cyclase.

Animals↗
PubMed1990

Adsorption of local anesthetics on activated carbon: Freundlich adsorption isotherms.

We have shown that adsorbability of local anesthetics onto activated carbon, expressed by the partition coefficients at infinite dilution, correlated well with the pharmacological activity. However, there is no parameter that can singly express the tendency to be adsorbed. Adsorbability is a loosely defined term and its meaning varies with the adsorption model. This study showed that the logarithm of the adsorbed amount of drugs was linearly related to the logarithm of the free drug concentration, in conformity to the Freundlich adsorption isotherms. The slope of the double logarithmic plot is expressed by 1/N in the Freundlich equation and is considered to be inversely related to the drug affinity to the adsorbent. The slope was used to evaluate the tendency to be adsorbed, or "adsorbability" of seven aromatic amine local anesthetics. Phenobarbital was included to compare anionic drugs in contrast to the cationic local anesthetics. The slopes were nearly equal between the cationic and neutral local anesthetics. Apparently, the lower hydrophobicity of the cationic forms is compensated by the electrostatic attraction from the negative charges present on the activated carbon surface. With phenobarbital, the slope value of the anionic form was larger than the neutral form. The lower affinity of the anionic form may be caused by the electrostatic repulsion. The molecular size parameters (i.e., molecular weight, molar refraction, and parachor) showed a linear relationship to the slope values. It may be possible to estimate the affinity-related slope values from these parameters.

Adsorption↗
PubMed1990

Effects of meals and physical activity on blood pressure variability in elderly patients. A preliminary study.

Twenty-four-hour blood pressure (BP) was determined noninvasively in 11 ambulatory (active group, 78 +/- 2 years old) and 11 bedridden (passive group, 79 +/- 2 years old) elderly patients. Postprandial reduction in BP was evident in both groups. BP variability during the daytime was significantly greater in the active group than in the passive group. Consequently, only patients of the passive group showed a significant day-night difference in BP and a significant circadian rhythm of BP as well. We conclude the following: 1) postprandial reduction in BP contributes to BP variability during daytime in elderly patients, 2) the greater BP variability seen in ambulatory patients obscures the day-night rhythm of BP, and 3) the day-night rhythm of BP exists in bedridden patients.

Aged↗
PubMed1990

Circadian variations of urinary dopamine, norepinephrine, epinephrine and sodium in normotensive and hypertensive subjects.

Under standardized conditions, we determined circadian urinary excretion of sodium (Na) and free dopamine (DA), norepinephrine (NE) and epinephrine (E) in 20 normotensive, 20 borderline hypertensive and 10 mild hypertensive middle-aged men. The 24-hour excretions of water, Na, DA, NE and E were comparable between the normotensives and the hypertensives. In the total study population, these parameters showed significant time-related changes: high excretion during the daytime and low excretion in the night. The circadian variations of urinary DA, NE and E were similar among the 3 groups. The circadian curve of urinary DA was similar to those of Na and water excretion. In the total study population, 24-hour water and Na excretion correlated positively with urinary DA, but not with NE or E. These results suggest that endogenous DA may play a role in the circadian variation of water and sodium metabolism. The circadian excretion of urinary catecholamines may not be altered in middle-aged subjects with borderline or mild hypertension.

Age Factors↗