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Biomedical subjects

K Fukiyama

Publications and source records attributed to K Fukiyama.

At least 73 records · Page 4Linked to original sources
PubMed1996

Mild mental stress increases insulin sensitivity in healthy young men.

We examined if mental stress alters insulin sensitivity and renal sodium handling in 11 normotensive young men. Following a 60-minute period of equilibration, we performed euglycemic hyperinsulinemic glucose clamp for 150 minutes. The clamp period was divided into three phases; control phase for 90 minutes (I), mental arithmetic phase for 30 minutes (II), and recovery phase for 30 minutes (III). Blood pressure, heart rate and glucose disposal rate (M value) significantly elevated during phase II of the stress study. In a time control study, in which mental arithmetic was not loaded during phase II, blood pressure was kept constant and the changes in M value from phase I to phase II were significantly smaller than those in the stress study. In both studies, fractional excretion of sodium did not significantly change throughout the study period. Thus, insulin sensitivity concerning glucose metabolism increased in response to mild mental stress. However, the effect of insulin on sodium handling was not altered by the stress.

Adult↗
PubMed1996

Hypertension in dialysis patients: a cross-sectional analysis.

To clarify the current status of blood pressure control in chronic dialysis patients, we investigated a large group of patients undergoing dialysis in Okinawa, Japan. A set of cross-sectional data of 18 variables, including age, antihypertensive medication, dose of dialysis, blood chemistry findings and predialysis blood pressure, were obtained in 1,243 patients (524 females, 719 males) aged 14 to 93 years who were on hemodialysis in January 1991. Systolic and diastolic blood pressures in patients taking antihypertensive medication (160.8 +/- 0.8/84.6 +/- 0.5 mmHg, mean +/- SEM) were significantly (P < 0.0001) higher than in those were not taking antihypertensive medication (141.3 +/- 0.8/76.9 +/- 0.5). Stepwise regression and univariate analysis methods were used to determine the independent predictors of blood pressure. Antihypertensive medication was positively associated with systolic and diastolic blood pressure. However, the mortality rate of the two groups during the following four years did not differ (antihypertensive-medicated group 23.1% vs. non-medicated group 20.9%). In conclusion, hypertension does not appear to be adequately controlled in our dialysis patients, despite the widespread use of antihypertensive medications.

Adult↗
PubMed1996

An epidemiologic analysis of parathyroidectomy in chronic dialysis patients. The Okinawa Dialysis Study Group.

Parathyroidectomy (PTX) is one of the treatments of choice for secondary hyperparathyroidism in chronic dialysis patients. Due to the large increase in long-term dialysis patients, hyperparathyroidism is becoming a common clinical problem. Several studies on PTX have reported various surgical procedures, but limited information is available on the incidence and risk factors of the surgery. The Okinawa Dialysis Study (OKIDS) registry is a community-based dialysis registry. It covers the entire area of Okinawa from when the use of chronic dialysis began in 1971. By the end of 1990, a total of 1,986 chronic dialysis patients were registered and 128 of these had undergone PTX by the end of 1993. The cumulative incidence of PTX was 4.3 in DM and 15.2 in non-DM per 1,000 patient-years. About half of the PTX patients underwent the surgery within 10 years of dialysis. By logistic analysis, the risk of PTX was seen to increase significantly with the duration of dialysis, P < 0.0001. Other clinical variables such as sex, age at the start of dialysis and the presence of diabetes mellitus were not significant predictors of PTX. The probability of PTX increased linearly with the duration of dialysis (r = 0.83, p < 0.0001). After the introduction of active vitamin D in 1981, the probability of PTX was significantly decreased (p < 0.05) compared to the pre-vitamin D period ('71-'80). With prolongation of the duration of dialysis, the risk of PTX increased steadily and was estimated to be 10 percent in 10 years and 20 percent in 20 years. Other uremic factors determining a pathological transformation of parathyroid tissue from reactive to autonomous growth remained to be investigated.

Adult↗
PubMed1996

Blood pressure and risk of end-stage renal disease in a screened cohort.

We prospectively studied a total of 107,192 subjects over 18 years of age (51,122 men and 56,070 women) who participated in dipstick urinalyses and blood pressure measurements in 1983. The subjects represented approximately 13.7% of the entire Okinawan adult population of 780,000 according to the 1980 Census. Independently, data for all dialysis patients registered from April 1, 1983 to March 31, 1994 were analyzed; the total number of end-stage renal disease (ESRD) dialysis patients was 2,009 (1,126 men and 883 women) during the study period. Dialysis patients who had been in the 1983 mass screening and who later required dialysis during the study period were identified and verified by reviewing the medical records. ESRD developed in 193 (105 men and 88 women) participants from the 1983 health screening. In this mass screening setting, high diastolic blood pressure was identified as the significant predictor of ESRD with an adjusted odds ratio of 1.39 and a 95% confidence interval of 1.17 to 1.64.

Adolescent↗
PubMed1996

A community-based evaluation of the effect of renal transplantation on survival in patients with renal-replacement therapy.

The relative effect of renal transplantation on survival was examined in chronic dialysis patients in Okinawa, Japan. Of 3,035 patients (1,722 men and 1,313 women) who were registered by the end of 1994 and followed up until April 1, 1995, 141 (91 men and 50 women) had undergone a renal transplantation during the follow-up period. The type of donor was a cadaver in 38 (26.9%) and a living relative in 103 (73.1%). At the end of the follow-up period, 12 (8.5%) of the patients with a renal transplant had died, 35 (24.8%) had returned to dialysis treatment, and 94 (66.7%) were alive with a functioning graft. In the patients who did not receive a transplant, 1,134 (39.2%) had died and 1,760 (60.8%) were alive and on dialysis. Cox proportional hazard analysis was performed with adjustment for sex, age at first dialysis, presence of diabetes mellitus, year of first dialysis, and predialysis co-morbid conditions. The hazard ratio (95% confidence interval) in the group with a transplant was 0.33 (0.18 to 0.59) when the hazard ratio of the group without a transplant was taken as 1.00. The patient survival rate was better in the former group. Our data provide fundamental evidence supporting the effectiveness of renal replacement as treatment. Whether the life-saving merit of renal transplantation is substantial enough to actively encourage donation remains to be clarified.

Adult↗
PubMed1996

[Athlete's heart].

Explore the source record for details and available documents.

Cardiomegaly↗
PubMed1995

Modulation of baroreflex function by angiotensin II endogenous to the caudal ventrolateral medulla.

Neurons in the ventrolateral medulla (VLM) mainly determine the tonic sympathetic activity. The caudal VLM (CVLM) relays baroreflex signals to the rostral VLM. We have reported that endogenous angiotensin II (ANG II) contributes to the ongoing activity of the VLM neurons. In the present study, we examined if ANG II endogenous to the CVLM modulates the baroreflex function in anesthetized normotensive Sprague-Dawley rats. Changes in renal sympathetic nerve activity (RSNA) in response to changes in mean arterial pressure (MAP) induced by i.v. infusion of phenylephrine and nitroglycerin were recorded before and after bilateral microinjection of [Sar1, Thr8]-ANG II, an ANG II antagonist, into the CVLM. The ANG II antagonist injection into the CVLM significantly increased MAP and RSNA by 17.6 +/- 8.0 mmHg (mean +/- S.D.) and 36.3 +/- 18.1%, respectively. It also significantly increased the baroreflex sensitivity (BS) from -0.49 +/- 0.38 to -0.74 +/- 0.37%/mmHg during nitroglycerin infusion. In contrast, the BS examined by phenylephrine infusion was not altered by the pretreatment with ANG II antagonist. Injection of artificial CSF affected neither the baseline values of MAP and RSNA nor the BS. These results suggest that ANG II endogenous to the CVLM exert a modulating role in baroreflex control of RSNA.

Adrenergic Fibers↗
PubMed1995

Brain angiotensin II contributes to the development of hypertension in Dahl-Iwai salt-sensitive rats.

OBJECTIVE: To examine the role of brain angiotensin II in the development of salt-induced hypertension in Dahl-Iwai salt-sensitive (DIS) rats. METHODS: Male DIS and Dahl-Iwai salt-resistant (DIR) rats aged 5 or 6 weeks were implanted with an intracerebroventricular cannula, and either chronic intracerebroventricular infusion of 5 micrograms/day CV-11974, a non-peptide type-1 angiotensin II receptor antagonist or artificial cerebrospinal fluid (aCSF) was started. The rats were fed a diet containing 8% sodium chloride. RESULTS: On day 11 or 12 of chronic infusion, DIS rats given CV-11974 intracerebroventricularly exhibited a significantly lower mean arterial pressure than DIS rats given aCSF intracerebroventricularly or intravenous infusion of CV-11974. In DIR rats, intracerebroventricular infusion of CV-11974 did not alter the mean arterial pressure. Sodium and water balances were similar in all of the groups. Plasma vasopressin and noradrenaline levels did not differ among the groups, although the plasma renin concentration was significantly lower in DIS rats given aCSF intracerebroventricularly. Arterial baroreflex control of heart rate and pressor response to intravenous injection of phenylephrine were not altered in rats given CV-11974 intracerebroventricularly. CONCLUSION: The integrity of the brain renin-angiotensin system is necessary for the development of salt-induced hypertension in DIS rats.

Angiotensin II↗
PubMed1995

Alterations of alpha 1-adrenergic receptor densities in right and left ventricles of spontaneously hypertensive rats.

To clarify whether alpha 1-adrenergic receptors contribute to cardiac hypertrophy, we examined alpha 1-adrenergic receptor densities in the right and left ventricles of 5- and 20-week-old spontaneously hypertensive rats (SHR) and Wistar Kyoto rats (WKY) using [3H]prazosin. Also, we analyzed a pharmacologically distinct subtype of alpha 1-adrenergic receptors by pretreatment with chloroethylclonidine. The ratio of right ventricular weight to body weight as well as left ventricular weight to body weight was higher in SHR than in WKY at 5 weeks of age. At 20 weeks of age, only the left ventricular weight to body weight ratio was higher in SHR. At 5 weeks of age, the right and left ventricular alpha 1-adrenergic receptor densities in SHR were greater than those in WKY (LV 1760 vs. 1275, RV 2543 vs. 1521 fmol/mg protein). At 20 weeks of age, only right ventricular alpha 1-adrenergic receptor density remained higher in SHR (1425 vs. 885 fmol/mg protein). The percentage of pharmacologically distinct alpha 1A receptor was higher in the right ventricle of SHR than in that of WKY at 5 weeks of age (25% vs. 18%). There were no significant differences in the dissociation constants among the alpha 1-adrenergic receptor assays. These findings suggest that an increase in alpha 1-adrenergic receptors might be involved in cardiac hypertrophy in the early phase of hypertension in SHR.

Adrenergic alpha-Antagonists↗
PubMed1995

Alpha 2-adrenoceptors in brain and kidney during development of hypertension in Dahl-Iwai salt-sensitive rats.

BACKGROUND: Both renal and extrarenal factors have been considered to contribute to the development of hypertension in Dahl salt-sensitive rats, but contents of both factors have not been established precisely. AIM: To clarify the role of those factors in the sympathetic nervous system, we examined the regulation of alpha2-adrenoceptors in the lower brainstem and the renal tubular basolateral membranes simultaneously during the development of salt-induced hypertension in Dahl-Iwai salt-sensitive rats. METHODS: Dahl-Iwai salt-sensitive or resistant rats were fed a high (8.0% NaCl)- or low (0.3%)- salt diet from 4 to 6 or 10 weeks of age. At 4, 6 and 10 weeks of age, the plasma membranes of the lower brainstem and the renal tubular basolateral membranes were obtained simultaneously and alpha 2-adrenoceptors were quantified by a radioligand binding assay using 3H-rauwolscine. RESULTS: In the salt-sensitive rats, systolic blood pressure was significantly higher in those fed a high-salt diet than in those fed a low-salt diet. In the salt-resistant rats, both the high- and the low-salt groups showed similar blood pressure levels. At 6 weeks of age, alpha 2-receptor densities of the salt-sensitive rats fed a high-salt diet were lower in the lower brainstem and higher in the renal basolateral membranes than those fed a low-salt diet. In contrast, in the salt-resistant rats, both the high- and the low-salt groups had similar densities. At 10 weeks of age, the difference between the high- and the low-salt groups in the salt-sensitive rats disappeared in both the brainstem and the renal basolateral membranes. CONCLUSIONS: Alpha 2-adrenoceptor regulation in the brainstem and the renal basolateral membranes differs between Dahl-Iwai salt-sensitive and salt-resistant rats. The modulation of alpha 2-adrenoceptors by a high salt intake may be essential particularly in the early phase of the development of salt-induced hypertension.

Animals↗
PubMed1995

[Two siblings with adult-onset sialidosis type I (cherry-red spot-myoclonus syndrome)].

Cases of two Japanese siblings with adult-onset sialidosis type I are reported. A 38-year-old man had gradually developed involuntary movement of the extremities from the age of 31. On admission, he had no skeletal abnormalities and hepatosplenomegaly, but showed myoclonus of the extremities and dyskinesia in the perioral region. We found cherry-red spots and a giant potential in a somatosensory evoked potential (SEP) study. Then, the diagnosis of sialidosis type I was confirmed by low activity of white blood cell sialidase. MRI (SE, TR 2,000/TE 100, 40) of the brain revealed a small high intensity are in the cerebral white matter adjacent to the posterior horn of the right cerebral ventricle. To our knowledge, no report on MRI findings of the brain in sialidosis type I has been reported. So far, it is uncertain whether or not such a lesion is caused by sialidosis. He was treated with clonazepam, sodium valproate, diphenylhydantoin, or haloperidol. The former two improved the symptoms, but SEP findings did not change. The subject's 43-year-old brother had also myoclonus and epilepsy since the age of 31, and low activity of sialidase. Their mother had no symptoms, but her sialidase activity level was as low as that of a carrier. These two are the eighth and ninth cases of sialidosis type I in Japan to be confirmed by enzyme activity.

Adult↗
PubMed1994

An epidemiologic analysis of end-stage lupus nephritis.

We analyzed 566 patients (515 females and 51 males) with systemic lupus erythematosus who were treated in Okinawa, Japan, from 1972 to 1991 and followed until April 1993. One hundred four patients (95 females and 9 males) died, and 51 were considered to have end-stage lupus nephritis. The annual incidence and prevalence, per million population in each sex, were increased from 16.0 and 66.0 in 1972 to 46.7 and 683.9 in 1991 in the female patients, and from 4.2 and 8.3 in 1973 to 8.3 and 70.0 in 1991 in the male patients, respectively. Cox proportional hazard analysis was done to determine the effects of several covariates on patients and renal survival. The patients' survival rate improved, as the hazard ratio (HR) was decreased to 0.69 (year of diagnosis, 1982 to 1986) and to 0.48 (year of diagnosis, 1987 to 1991) when the HR in patients diagnosed before 1981 was taken as 1.00. Similarly, we examined renal survival by using the Cox proportional model. For this analysis, the date of start of dialysis therapy was regarded as the time of renal death. Male patients had significantly poor renal survival; the HR was 3.64 (95% confidence interval, 1.89 to 6.98) when the HR in the females was taken as 1.00. However, age at diagnosis and year of diagnosis did not significantly affect renal survival. The cumulated incidence of end-stage lupus nephritis from the time of diagnosis of systemic lupus erythematosus was 3.1% at 5 years, 9.4% at 10 years, 15.5% at 15 years, and 21.0% at 20 years.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Effect of renal diseases and comorbid conditions on survival in chronic dialysis patients.

International and geographical differences in the survival rates of chronic dialysis patients can be explained by differences in primary renal disease, in the acceptance rate of elderly patients, and in predialysis comorbid conditions. Several studies have shown the effects of these factors on survival. However, in most studies, a large number of patients may leave for renal transplantation or transfer to other centers, so that precise analysis becomes impossible. Although the number of patients in our registry is not so large (n = 1,982), we have few such problems and were able to examine the effects of the above-mentioned factors on patient survival using the Cox proportional hazard model. Hazard ratios (HR) and 95% confidence intervals were 0.739 and 0.366-1.491 in patients with polycystic kidney disease (n = 38), 2.669 and 1.513-4.708 in patients with systemic lupus erythematosus (n = 39), 1.245 and 0.935-1.660 in patients with nephrosclerosis (n = 122), 1.815 and 1.447-2.229 in patients with diabetes mellitus (n = 374), and 1.595 and 1.201-2.117, respectively, in patients with other renal diseases (n = 146) when the HR in patients with chronic glomerulonephritis (n = 1,263) was taken as 1.00. HR and 95% confidence intervals were 1.222 and 1.016-1.470 in patients with one comorbid condition (n = 217) and 1.494 and 1.033-2.160, respectively, in patients with two comorbid conditions (n = 24) when the HR of patients with no predialysis comorbid conditions (n = 1,741) was taken as 1.00. Our data demonstrate the effects of renal diseases and number of predialysis comorbid conditions on the survival in chronic dialysis patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Neural effects on renal blood flow during acute hypotension vary with antihypertensive drugs.

To examine the neural effects of antihypertensive drugs on renal blood flow, we measured blood flow and renal sympathetic nerve activity simultaneously in conscious spontaneously hypertensive rats aged 13 to 15 weeks. One to two days after surgery, intravenous administration of manidipine (calcium antagonist, n = 10), doxazosin (alpha 1-adrenergic receptor antagonist, n = 9), and clonidine (n = 7) lowered mean arterial pressure by at least 20% from baseline levels. Manidipine initiated a reduction of renal blood flow when mean pressure decreased by 20 +/- 2 mm Hg. At the maximal decrease in renal blood flow (mean pressure, -33 +/- 2 mm Hg), percent decrease in flow (-27 +/- 2%) significantly correlated with percent increase in renal nerve activity (+205 +/- 40%, r = -.878). Doxazosin began to decrease renal blood flow at a level of arterial pressure similar to that in manidipine treatment, whereas the maximal decrease in flow (-19 +/- 2%; mean pressure, -33 +/- 2 mm Hg; nerve activity, +225 +/- 44%) was significantly less than that in manidipine treatment. Although clonidine decreased arterial pressure and renal nerve activity, renal blood flow did not decrease even at the maximal decrease in mean pressure of 29 +/- 1 mm Hg. The addition of clonidine to manidipine treatment suppressed reflexly enhanced renal nerve activity and restored blood flow to the pretreatment level despite pronounced hypotension. These results clearly demonstrate that antihypertensive drugs with blocking action on renal nerve activity are capable of maintaining renal blood flow and that those associated with reflex-induced enhancement of nerve activity exert deteriorating effects on renal blood flow. Furthermore, a decrease in renal blood flow induced by calcium antagonists is mainly attributed to reflexly enhanced renal nerve activity.

Animals↗
PubMed1994

Short-term effects of angiotensin II blockade on renal blood flow and sympathetic activity in awake rats.

To investigate the effects of an angiotensin II type 1 receptor antagonist (CV-11974) on renal blood flow and renal sympathetic nerve activity compared with a calcium antagonist (nicardipine), we measured both parameters in conscious spontaneously hypertensive rats aged 13 to 15 weeks. One to 2 days after surgery, CV-11974 (n = 9) and nicardipine (n = 8) were intravenously administered to decrease arterial pressure in a similar time course and degree of hypotension. CV-11974 increased renal blood flow by 23 +/- 4% at the maximal fall in mean arterial pressure (-32 +/- 1 mm Hg), and renal nerve activity increased by 70 +/- 7%. The maximal increase in renal blood flow (+27 +/- 4%) was observed when mean pressure was reduced by approximately 20 mm Hg. The maximal reduction of renal vascular resistance (-33 +/- 3%) correlated significantly with pretreatment levels of plasma renin concentration (r = -.792). In contrast, nicardipine produced a progressive reduction of renal blood flow and marked increases in heart rate and renal nerve activity. Increases in heart rate and nerve activity were greater than those with CV-11974 treatment (P < .001). At the maximal fall in mean pressure (-32 +/- 1 mm Hg), renal blood flow decreased by 23 +/- 4%, which was significantly correlated with percent changes in renal nerve activity (+150 +/- 11%, r = -.744). Renal denervation in another set of rats (n = 6) improved renal blood flow and renal vascular resistance responses to nicardipine.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin Receptor Antagonists↗