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Biomedical subjects

K Sakamoto

Publications and source records attributed to K Sakamoto.

At least 685 records · Page 38Linked to original sources
PubMed1990

Effect of age on contractile response to angiotensin II in rat aorta.

The effects of aging on contractile response to angiotensin II and tachyphylaxis to it were investigated using aortic strips from rats aged 1.5, 4 and 22 months. Whether the endothelium was present or not, the contractile response to angiotensin II was greater and tachyphylaxis to it was less in 1.5-month-old rats than in 4- and 22-month-old rats. The differences between 4- and 22-month-old rats were not significant. Removal of the endothelium enhanced angiotensin II-induced maximal contraction and depressed the tachyphylaxis, these endothelial effects being greater in 4- rather than in 1.5-month-old rats. When the contractile force of angiotensin II was adjusted to a similar level for 1.5- and 4-month-old rats, the endothelial effect on the tachyphylaxis was greater in the 4-month-old rats, but no significant difference was noted in the endothelial effect on the contractile force. These results suggest that during growth, the contractile response of rat aorta to angiotensin II decreases while the endothelial effect on it increases.

Acetylcholine↗
PubMed1990

The extrarenal effects of atrial natriuretic peptide on body fluid distribution.

To study the effects of atrial natriuretic peptide (ANP) on body fluid volume regulation, we estimated the changes in intra- and extravascular fluid volume by measuring hematocrit (Hct), plasma protein concentration and water balance, and the changes in intra- and extracellular fluid volume by the electrical impedance method during intravenous infusion of ANP. We did two studies, as follows: ANP was infused into 18 patients with essential hypertension, 29 with renal parenchymal hypertension and 15 normotensives at 0.025 microgram/kg/min for 40 min. Both hypertensive groups showed greater natriuretic responses to ANP than normotensives. ANP infusion into essential hypertensive patients increased the urinary excretion of water by 125%, Na by 205%, Hct by 4.2% and plasma total protein (TP) by 5.2% (each P less than .001). In 9 patients (1 with renal hypertension and 8 normotensives) who did not show a natriuretic response (-2.1%), the infusion of ANP also significantly increased Hct (3.8%) and plasma TP (3.1%, each P less than .01). The electrical impedance method was applied to 12 subjects to simultaneously detect the intracellular (Ri) and extracellular resistivities (Re), of which reciprocals reflect the fluid volume in the extra- and intracellular spaces, respectively. ANP infusion increased Re in all subjects (3.96 +/- 0.16 [SE] v 4.03 +/- 0.16 omega.m, P less than .05), but decreased Ri in 7. Changes in urinary Na excretion correlated positively with those in both Re (r = 0.62, P less than .05) and Ri (r = 0.75, P less than .01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Detection of tumor associated antigen, PA8-15, in sera from pancreatic and gastrointestinal carcinoma patients.

A sandwich enzyme immunoassay was set up to measure tumor associated antigen (antigen PA8-15) detected by monoclonal antibody PA8-15. The cut-off value was set at 55 U/ml. Tests on 437 sera samples from patients with malignant or benign diseases yielded the following positive percentages: esophageal cancer, 9.1%; gastric cancer, 23.1%; colorectal cancer, 44.8%; hepatoma, 32.6%; biliary tract cancer, 47.5%; pancreatic cancer, 84%; lung cancer, 30.8%; breast cancer, 16%; benign diseases, 13.2%. Positive antigen PA8-15 levels in patients with gastric, colorectal and pancreatic cancers, increased with the progression of clinical stage. When antigen PA8-15 was monitored in 11 various cancer cases before and after surgery, a decrease in PA8-15 value was revealed in all resected patients postoperatively, whereas a more than 100% increase in PA8-15 values was noted in non-resected patients. Compared with CEA and CA19-9, the highest positive PA8-15 rate was seen in pancreatic cancer patients. By combining the rates of positive sera obtained with each tumor marker, the overall percentage increased. These results suggest that measuring serum PA8-15 levels will aid in serological cancer diagnoses, particularly pancreatic cancer.

Adolescent↗
PubMed1990

Radiation dose to mouse liver cells from ingestion of tritiated food or water.

Tritium incorporated into tissues and DNA of mice was studied after daily ingestion of tritiated food or tritiated water. The tritiated food used was a commercial preparation mixed with brine shrimp that had been reared in tritiated sea water. After ingestion of tritiated food or water for up to 22 d, the specific activity of 3H in tissues was measured as tissue-free-water 3H, tissue-bound 3H, and DNA-bound 3H. Carbon-14 glucose was added to food and drinking water to compare the 3H intake from food with that from water. The specific activity of 3H in tissues was then corrected by the specific activity of 14C in tissues to determine the 3H incorporation from the same amount of ingested food and water. DNA-bound 3H after the ingestion of tritiated food was 4.6 times higher than that of tritiated water, while tissue-bound 3H was 2.2 times higher. The radiation dose to liver from 3H incorporated through food was twofold higher than from tritiated water, which was mainly from the high incorporation of 3H into DNA. Our results demonstrated that the dose calculation based on tissue-free-water 3H alone would under-estimate the radiation exposure of the human population exposed to tritiated food.

Animals↗
PubMed1990

Effects of diltiazem on the pharmacokinetics of nifedipine.

To evaluate the effect of diltiazem pretreatment (60 mg three times a day for 3 days) on pharmacokinetics and pharmacodynamic effect of nifedipine, six healthy subjects received 20 mg nifedipine orally on two occasions using a double-blind cross-over, placebo-controlled method. Diltiazem induced a marked increment of the area under the plasma concentration-time curve (AUC) for nifedipine by a mean of 140% and reduced the total body clearance (Cl) from 0.0043 +/- 0.0019 to 0.0017 +/- 0.0006 ml/min/kg (p less than 0.05, mean +/- SD). The biological half-life (t1/2) of nifedipine was prolonged from 2.46 +/- 0.65 to 3.21 +/- 0.92 h (p less than 0.05) without any changes in indocyanine green (ICG) clearance. Diltiazem did not produce significant changes of AUC, Cl, and t1/2 for the acid metabolite of nifedipine. Blood pressure (BP) after nifedipine administration with diltiazem pretreatment was more decreased than that without diltiazem. Both a decreased hepatic clearance and an increased bio-availability of nifedipine by diltiazem probably explain the significant changes in pharmacokinetics and hemodynamics of nifedipine. A clinically important drug interaction may occur with nifedipine when diltiazem is administered concurrently.

Adult↗
PubMed1990

Mechanism of tolerance following class I--disparate renal allografts in miniature swine. Cellular responses of tolerant animals.

Previous studies utilizing a recombinant MHC haplo-type in our partially inbred miniature swine herd have demonstrated that some recipients matched only for SLA class II show long-term acceptance of renal allografts without exogenous immunosuppression. Such animals have been shown to develop systemic tolerance as evidenced by prolonged rejection times of subsequent donor-specific, but not third-party, skin grafts. In the present studies in vitro cellular responses of long-term tolerant animals and of 7 animals studied sequentially are presented. Long-term tolerant animals demonstrated responses consistent with the absence of the class I reactive helper populations normally present in naive controls. Animals studied sequentially segregated into two groups based on cellular reactivity and survival. All animals showed complete loss of antidonor class I cell-mediated lymphocytolytic (CML) reactivity by postoperative day 10. However, animals surviving less than 20 days maintained CML reactivity to donor class I plus third-party class II in the posttransplant period, while animals surviving greater than 40 days lost such reactivity. Addition of exogenous interleukin 2 could not reverse this loss. These studies suggest that tolerance induction to a renal allograft across a class I only difference involves effects on both helper and killer class I reactive cell populations.

Animals↗
PubMed1990

Acral granulomatous dermatosis.

A 17-year-old boy developed an acral granulomatous dermatosis which resembled clinically acrodermatitis continua of Hallopeau. The histology showed dermal and subcutaneous abscess formation with granulomas. The lesions responded to systemic corticosteroid therapy, with residual atrophy and contractures of the fingers.

Acrodermatitis↗
PubMed1990

Electroclinical study of video-game epilepsy.

Seven patients (five boys, two girls) with video-game epilepsy (VGE) are reported, which reflects the fact that these games have increased in popularity recently among Japanese children. Their ages at onset ranged from four to 13 years. The seizure phenomena were of three types: generalised tonic-clonic, partial seizure and headache. Interictal physical and neurological examinations were within normal limits. EEGs taken while they played video-games confirmed the diagnosis of VGE and revealed three triggers of seizures: flashing lights, special figure patterns and scene-changing. They were recommended to avoid playing video-games, but sodium valproate was effective if seizures persisted even after such avoidance.

Adolescent↗
PubMed1990

Relation of serum and erythrocyte magnesium levels to blood pressure and a family history of hypertension. A follow-up study in Japanese children, 12-14 years old.

Serum and erythrocyte magnesium concentrations (S-Mg, E-Mg) were measured in 122 junior high school students followed up for two years from 12 to 14 years of age, and the relationship to blood pressure and a family history of hypertension were investigated. The subjects who had high S-Mg and E-Mg levels at the first examination two years prior tended to show high levels after this follow-up. There were significant positive correlations between two intraindividual values of S-Mg and E-Mg. A similar tendency was found for blood pressure. Tracking phenomena were observed with these measures. The subjects who had high E-Mg levels at the first examination showed no blood pressure elevation during the two-year period. The subjects with a family history of hypertension [FH(+)] showed a higher degree of blood pressure rise during two years than those with no family history [FH(-)], with a significant difference in systolic blood pressure at the age of 14. E-Mg tended to be lower in the FH(+) group than in the FH(-) group with a significant difference in 14-year-old girls. These results suggest that a hereditary predisposition to hypertension is related to magnesium metabolism and that intracellular magnesium deficiency may influence blood pressure elevation in the FH(+) children.

Adolescent↗
PubMed1990

Potentiating effect of daunorubicin on vasocontractile responses to KCl and BAY K 8644 in rat aorta.

The effects of daunorubicin on vasoconstraction by several agonists have been investigated on isolated aortic strips from rats. Pretreatment of the strips with daunorubicin (17.7 microM) potentiated the contractile response to low concentrations of KCl or to BAY K 8644 but not to phenylephrine or clonidine. The maximal contractile response to KCl was not affected by the pretreatment while that to BAY K 8644 was increased. The potentiated response to KCl could be eliminated by addition of nifedipine (1 microM) or use of a calcium-free solution. The maximal contractile response to BAY K 8644 was greatly increased by partial depolarization with KCl (10 mM, final concn) in the control solution but only slightly increased by the partial depolarization in the solution with daunorubicin. These results suggest that daunorubicin facilitates activation of the voltage-dependent calcium channel and increases the contractile responses to KCl and BAY K 8644 in rat aorta.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1990

Predictors of duodenal ulcer healing during treatment with cimetidine.

A two phase study was performed to identify factors that influence the healing rate of duodenal ulcer. The study included an initial clinical trial in 145 patients and a second trial in a further 61 patients. All patients were prescribed cimetidine at a daily dose of 800 mg for six weeks. The factors examined were age, sex, inpatient or outpatient treatment, duration of present ulcer pain, past history of duodenal ulcer, smoking, drinking, the length of time it took for symptoms to resolve after beginning treatment, and the characteristics of the ulcers themselves. Eighty four per cent of the duodenal ulcers healed after six weeks. Using univariate and multivariate analyses, it was found that three factors indicated a significant delaying effect on healing: (1) symptoms that persisted two weeks after treatment had begun; (2) heavy smoking (20 or more cigarettes daily); and (3) severe narrowing of the duodenal bulb. Patients with none of the three unfavourable factors (n = 90) had a healing rate of 95.6% compared with patients with one (n = 45) or two or more (n = 10) factors, whose healing rates were 75.6% and 20.0% respectively (p less than 0.001). The corresponding figures in a second study were 88.9%, 55.0%, and 0%, respectively (p less than 0.001). A prognostic score based on these three factors represents the severity of duodenal ulcers with regard to healing in patients treated with cimetidine.

Adult↗
PubMed1990

Alu interspersed repeats: selfish DNA or a functional gene family?

Within the genomes of higher eukaryotic cells, short interspersed repetitive sequences appear to be ubiquitous, but also remarkably varied with respect to copy number and position. Many of these repeat families, including the human Alu family, can be transcribed by RNA polymerase III, and evidence has accumulated from a variety of sources that levels of repeat transcripts whose transcription is dependent on RNA polymerase III are sensitive to cellular transformation as well as changes in differentiation state. Although interspersed repetitive sequences have in the past been dismissed as nonfunctional, the discovery of the linkage to differentiation state, as well as other recent developments, suggest that the question of repeat sequence functionality should be reexamined.

Animals↗
PubMed1990

[Clinical study of UFT chemotherapy in renal cancer. Kyushu University Cooperative Study Group of Renal Cancer].

Clinical effects of UFT chemotherapy for renal cancer were evaluated by 19 collaborating hospitals. UFT (300-600 mg/day) was administered for more than 3 months. Of the 30 patients entered in this study, 21 were evaluable for the antitumor effects of the drug. Of the 21 evaluable patients, complete response (CR) was obtained in 2 patients, partial response (PR) in 1, no change (NC) in 7, progressive disease (PD) in 11, respectively. The response rate was 0% in patients with primary lesion and 21.4% in nephrectomized patients with metastatic lesion. Responses were observed in the metastases of lung, pleura and mediastinal lymph node. The main side effects in 27 patients were gastrointestinal symptoms. No significant abnormality was noted on blood laboratory data. In one patient the drug was discontinued within 3 months because of gastrointestinal symptoms. These results suggested that UFT chemotherapy for advanced renal cancer was clinically effective.

Adult↗