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Biomedical subjects

M Imanishi

Publications and source records attributed to M Imanishi.

At least 109 records · Page 6Linked to original sources
PubMed1992

[Investigation on unsuccessful endoscopic operation for cases with vesicoureteral reflux].

Endoscopic operation of vesicoureteral reflux (VUR) has several advantages such as less invasiveness and technical ease with the procedure and shorter hospitalization for the operation in comparison with coeliotomy, but the cure rate achieved by endoscopic operation compares unfavorably with that by coeliotomy. The unsuccessful cases of VUR by endoscopic operation were investigated to promote the success rate by endoscopic operation. Of 66 ureters in 55 patients 50 were successfully treated with the first operation, and 4 of 8 ureters with the second one. All 15 infants were cured, but the cure rate in females between 17 and 45 year old was significantly low (57%). An equally high cure rate was obtained by the endoscopic operation even in patients who had a high grade VUR, patulous ureteral orifices, an underlying neurogenic bladder, or episodes of urinary tract infection. All ureters were cured just after operation. The recurrence of VUR occurred in 19 ureters (29%) and 16 ureters were discovered at one month examination after operation, which indicates that olive oil dissolving teflon paste was partly absorbed to bladder tissue. Teflon paste shifted to internal urethral orifice in 4 unsuccessful ureters. Based on these findings, the endoscopic operation should be considered to be the preferred treatment among others in the management of VUR and the injection of sufficient volume of teflon paste into submucosal and muscular space of the bladder trigone could promote the cure rate.

Adolescent↗
PubMed1992

[Treatment of rejection with deoxyspergualin after renal transplantation].

Deoxyspergualin (DSG), which is a new immunosuppressive drug developed in Japan, is expected to be an immunosuppressant for the treatment of rejection, because it has immunosuppressive action different from that of other drugs. In the present study we used DSG to treat renal allograft rejection of in total 17 cases; 6 cases with acute rejection, 8 with chronic rejection and 3 with acute on chronic rejection. We infused DSG very slowly over 3 hours at a dose of 3-7 mg/kg/day for 5-7 days. Four cases (44.4%) with acute or acute on chronic rejection showed excellent response to DSG, three cases (33.3%) showed fair response and two cases (22.3%) did not respond at all. We also used DSG in patients with chronic rejection. In many of them, the increase in serum creatinine was suppressed. Ten of the total patients (58.8%) developed side effects including leukocytopenia, thrombocytopenia, numbness of the fact etc. No patients needed discontinuation of DSG. From the above results, we think that DSG is a safe and effective drug to treat acute rejection. Furthermore, we could get the results which suggest that DSG is effective for the treatment of chronic rejection.

Adolescent↗
PubMed1992

Effect of manidipine, a new calcium antagonist, on intrarenal hemodynamics in essential hypertension.

The effect of manidipine, a new Ca2+ antagonist, on intrarenal hemodynamics was assessed in essential hypertension and compared with nicardipine, a previously studied Ca2+ antagonist. Identical 2-week studies were repeated before and during the administration of manidipine (10 mg once daily, 2 weeks) in 3 patients with essential hypertension who were given regular- and sodium-restricted diets for 1 week each. The renal function curve (pressure-natriuresis relationship) was drawn by plotting the urinary sodium excretion rate on the y-axis as a function of the systemic mean arterial pressure (MAP) on the x-axis. Assuming that the difference between MAP and the extrapolated x-intercept of the renal function curve represents the effective filtration pressure across the glomerular capillary walls, the intrarenal hemodynamics were calculated (e.g., afferent arteriolar resistance (RA), efferent arteriolar resistance (RE), and glomerular pressure (PG)). During the regular sodium diet, MAP was lowered from 100 +/- 7 to 93 +/- 5 mmHg (p < 0.04) and the effective filtration pressure was lowered from 20 +/- 2 to 10 +/- 3 mmHg (p < 0.05); the renal plasma flow rate (pre: 560 +/- 74 vs. post: 627 +/- 108 mL/min) and glomerular filtration rate (82 +/- 10 vs. 78 +/- 5 mL/min) were not altered. RA remained unchanged (3,800 +/- 700 vs. 3,400 +/- 300 dyn.sec.cm-5; % reduction: 4 +/- 16%) whereas RE was reduced from 4,300 +/- 700 to 3,300 +/- 800 dyn.sec.cm-5 (19 +/- 15%). Thus, PG was lowered from 58 +/- 2 to 50 +/- 2 mmHg (13 +/- 3%), which parallels with the reduction in MAP.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Pressure↗
PubMed1992

[Evaluation of kidney graft function with dynamic MRI--preliminary report].

The value of dynamic magnetic resonance imaging (MRI) in the examination of the function of transplanted kidneys was examined. Dynamic MRI was performed on 14 renal transplant patients. After the injection of Gd-DTPA (dimeglumine gadopentetate), we used small tip angle gradient echo (STAGE) technique with a flip angle of 20 degrees. The cortex was higher in signal intensity of well functioning grafts than the medulla before the injection in Gd-DTPA. Signal intensity of the cortex decreased after 30 seconds. After 1 minute the signal intensity of the cortex recovered and low intensity band meaning passage of Gd-DTPA at corticomedullary differentiation was displayed. Signal intensity of the medulla decreased after 3 minutes. Signal intensity of the parenchyma of transplanted kidney after 5 minutes was much the same as that before injection. Image of poor functioning grafts displayed unclear figures. Time-intensity values of both cortex and medulla in well functioning grafts decreased rapidly after about 2 minutes, and rose thereafter. Time-intensity curves of both cortex and medulla were almost flat on and after 5 minutes. Time-intensity curves of both cortex and medulla in poor functioning grafts were almost flat through out the examination. We concluded that effective parameters of the graft function for the time-intensity curve were delta I1 and delta I2. Dynamic MRI was suggested to be useful in the evaluation of kidney graft function.

Contrast Media↗
PubMed1992

The association between salt sensitivity of blood pressure and family history of hypertension.

1. The salt sensitivity index (SSI) and family history of hypertension were studied in 140 hospitalized patients with essential hypertension to clarify whether salt sensitivity of blood pressure is related to familial disposition to hypertension. 2. SSI was calculated by dividing the change of mean blood pressure by that of urinary sodium excretion when salt intake was restricted from 15 to less than 3 g/day. 3. Family history of hypertension was classified into three groups depending on the presence or absence of hypertension in the father, mother and siblings. 4. The group without a family history of hypertension showed a significantly lower SSI value than other groups. 5. In multiple regression analysis undertaken within each gender, SSI showed significant partial correlations with blood pressure and family history of hypertension in the female group (r = 0.402 and 0.265, respectively), whereas in the male group it showed a positive correlation only with blood pressure (r = 0.501). These results indicate that salt sensitivity of blood pressure is related to familial disposition to hypertension. This association was more apparent in the female than male group and its gender difference can be partially attributed to the fact that blood pressure in the female group is more sensitive to salt.

Blood Pressure↗
PubMed1992

A gender difference in the association between salt sensitivity and family history of hypertension.

We examined 174 subjects (82 men and 92 women) with essential hypertension to determine whether gender played an important role in the association of blood pressure (BP) familial disposition, and hypertension. To evaluate the salt sensitivity of BP, we measured changes in blood pressure after restricting salt intake from about 15 g/day to less than 3 g/day. The familial disposition to hypertension was categorized into four groups according to the presence or absence of hypertension in the father, mother, and siblings. If none, one, two, or three family members had hypertension, they were assigned the FH(-), FH(+), FH(++), and FH( ) groups, respectively. Only in women did the FH(-) group show a significantly smaller blood pressure reduction than that of the other groups. The mean BP reduction in the four groups was 4.1 +/- 1.9, 8.5 +/- 1.1, 10.1 +/- 1.5, and 11.2 +/- 2.8 mm Hg (mean +/- SEM), respectively. This difference in BP reduction was not observed in men. Multiple regression analysis, using percent changes in mean BP as the dependent variable and other factors as independent variables, also showed a significant partial correlation coefficient for familial disposition to hypertension only in women. Thus, the relationship between salt sensitivity and familial disposition to hypertension differed according to gender. This difference may provide an important insight into the hereditary nature of hypertension.

Adult↗
PubMed1991

Different mechanisms of polyuria and natriuresis associated with paroxysmal supraventricular tachycardia.

The mechanism of polyuria associated with paroxysmal supraventricular tachycardia (SVT) was investigated in 8 patients. SVT was induced artificially and sustained for 60 minutes. Urine and blood samples were collected every 30 minutes. During the latter half of SVT, urine flow increased twofold in the control subjects before SVT. Urinary sodium excretion increased significantly (p less than 0.01) within 30 minutes after SVT. Urinary excretion of antidiuretic hormone (ADH) decreased (p less than 0.01) during the latter half of SVT and increased (p less than 0.01) after SVT, respectively. Plasma level of ADH did not change during SVT but increased (p less than 0.05) after SVT. The concentration of plasma atrial natriuretic polypeptide (ANP) increased significantly (p less than 0.05) before SVT ended. Urinary excretion of prostaglandin E2 increased significantly (p less than 0.05) after termination of SVT. The percent changes in the urinary excretion of prostaglandin E2 were correlated (r = 0.713, p less than 0.001) with those of ADH. There was also a correlation (r = 0.6, p less than 0.001) between the percent changes in the urinary excretion of prostaglandin E2 and those of sodium. Their findings suggest that the polyuria during SVT is attributed mainly to the inhibition of ADH release and that the natriuresis after SVT is due not only to the increased ANP but also to the increased renal prostaglandin E2 probably stimulated by ADH.

Adult↗
PubMed1991

Effects of brain natriuretic peptide on renin secretion in normal and hypertonic saline-infused kidney.

The effects of brain natriuretic peptide (BNP) on renin secretion were evaluated in normal and hypertonic saline-infused kidneys of anesthetized dogs. In the normal kidney (N = 5), intrarenal infusion of porcine BNP-(1-26) (pBNP) at a dose of 50 ng/kg per min attenuated the renin secretion rate significantly to 9 +/- 27% of control without exerting a significant effect on mean arterial pressure (MAP), renal blood flow (RBF) or glomerular filtration rate (GFR); urine flow (V) was significantly increased to 260 +/- 33% of control and urinary excretion of sodium (UNaV) to 480 +/- 140% of control. In the hypertonic saline infusion group (N = 6), intrarenal infusion of hypertonic saline (20% w/v) at 0.5, 0.8, and 1.0 mEq NaCl/min caused a decrease in GFR and natriuresis in a dose-dependent manner. The renin secretion rate was attenuated by hypertonic saline infusion (1 mEq NaCl/min) to 87 +/- 31% of control. In another group (N = 6), administration of pBNP at a dose of 50 ng/kg per min during hypertonic saline infusion (1 mEq NaCl/min) increased the renin secretion rate to 196 +/- 57%, increased RBF to 160 +/- 13%, increased GFR to 137 +/- 22%, increased V to 221 +/- 29%, and increased UNaV to 218 +/- 29% of the values measured during hypertonic saline infusion. Our results indicate that BNP inhibits renin secretion through sodium delivery to the macula densa and effectively inhibits the tubuloglomerular feedback response that is activated by intrarenal hypertonic saline infusion.

Animals↗
PubMed1991

Effect of a calcium-entry blocker, nicardipine, on intrarenal hemodynamics in essential hypertension.

The effects of a calcium-entry blocker, nicardipine, on intrarenal hemodynamics were studied in essential hypertension. A 4-week study was performed in eight patients with essential hypertension who were given a regular sodium diet in the first and third weeks, and a sodium-restricted diet in the second and fourth weeks. Nicardipine, 60 mg/d, was administered in the third and fourth weeks. The urinary sodium excretion rate (UNaV) was plotted on the y-axis against the mean arterial pressure (MAP) on the x-axis before and after the administration of nicardipine. Assuming the difference between MAP and the x-intercept of this renal function curve represents the effective filtration pressure across the glomerular capillaries, the intrarenal hemodynamics such as afferent arteriolar resistance (RA) and efferent arteriolar resistances (RE), glomerular pressure (PG), and gross filtration coefficient (KFG) were calculated. Although the MAP on regular salt diet was lowered from 125 +/- 3 to 109 +/- 2 mm Hg by nicardipine, neither the renal blood flow rate (RBF) (670 +/- 40 mL/min) nor the glomerular filtration rate (GFR) (79 +/- 2 mL/min) was altered. The RA was estimated to be reduced from 9,300 +/- 900 to 7,400 +/- 700 dyne.s.cm-5 (P less than 0.01), while no changes were noted in RE (4,900 +/- 400 dyne.s.cm-5), PG (50 +/- 1 mm Hg), or KFG (0.180 +/- 0.041 [mL/s]/mm Hg). Essential hypertension has been characterized by a prominent increase in RA, resulting in maintenance of normal PG. This Ca-entry blocker worked to normalize intrarenal hemodynamics in essential hypertension by dilating afferent arterioles alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Diet, Sodium-Restricted↗
PubMed1991

Aspirin test for differentiation of unilateral renovascular hypertension from hyperreninemic essential hypertension.

Responses of renin release and blood pressure to aspirin DL-lysine (ASP) were examined to find out if the responses could help in the differentiation between unilateral renovascular hypertension (RVH) and hyperreninemic essential hypertension (EHT). The two studies involved ten patients with unilateral RVH, eight with hyperreninemic EHT, and five with hyporeninemic EHT. In a radiological study, before and 30 min after an intravenous injection of ASP (18 mg/kg), renal venous and abdominal aortic plasma was sampled and assayed for prostaglandin (PG) E2 and plasma renin activity (PRA). Systemic blood pressure was measured serially. The reproducibility of the responses to ASP was confirmed in a bedside study. In unilateral RVH, ASP suppressed renin release from the stenotic kidney and reduced the renal vein PRA ratio to less than 1.5 via the inhibition of PG synthesis, which is accelerated in that kidney. The mean suppression of aortic PRA at this dose of ASP was 35% in these patients, and their blood pressure decreased in proportion to the suppression of PRA. However, in the two EHT groups, ASP elevated the mean blood pressure. The renal synthesis of PGE2 was inhibited by ASP in all patients, but the suppression of PRA, while small, was significant (19% in the aorta) in the patients with hyperreninemic EHT, and not significant in patients with hyporeninemic EHT. The different responses of blood pressure and PRA to ASP between RVH and EHT were reproducible in the bedside study.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Differential effects of endothelin-1 and big endothelin on canine kidneys.

Renal effects of endothelin-1 (ET-1, human, 1-21) and the equivalent molar concentration of big ET (human, 1-38) and the contributions of prostaglandins and endothelium-derived relaxing factor to these actions were examined. Intrarenal infusion of ET-1, at a dose of 0.4 pmol/kg/min, decreased renal blood flow (RBF), glomerular filtration rate (GFR), and urine output (V) to 62, 70, and 45% of control values, respectively. Additional aspirin-DL-lysine (ASP) treatment (25 mg/kg) caused marked decreases in RBF, GFR, and V to 20, 14, and 9% of control values, respectively. During ET-1 infusion, intrarenal infusion of NG-monomethyl-L-arginine (L-NMMA, 1 mumol/min) caused decreases in RBF, GFR, and V. In another group, intrarenal infusion of big ET at a dose equivalent to that of ET-1 did not significantly affect RBF, GFR, or urine output, which were 95, 107, and 84% of control values, respectively. Additional ASP treatment decreased these values to 78, 69, and 52% of control values, respectively. L-NMMA infusion during big ET infusion showed little effect on renal function. Our study demonstrated that intrarenal infusion of ET-1, at a dose of 0.4 pmol/kg/min, caused significant hemodynamic and functional changes in the canine kidney compared with an equivalent molar concentration of big ET.

Animals↗
PubMed1991

Characteristics and usage of different ureteral stent catheters.

Presuming that complications associated with ureteral stenting vary in type and occurrence depending on the material and cross-section of the stent, six types of stents immersed in 48 different preparations of artificial urine for 1 month to observe surface changes with a scanning electron microscope. As a result, there was less encrustation on the silicone material compared with other material types, probably due to the smoothness of the surface. This may be related with higher frequency of spontaneous removal or migration to the bladder of this catheter type. Because silicone catheters have softer and thicker walls with a narrow lumen, they may be appropriate for long-term stenting, but not for urinary drainage. In alkaline bacteriuria, struvite encrustation was observed on all stents. This reaction was especially intense with Towers peripheral stents, which had most irregular and uneven surfaces. In aseptic alkaline urine, calcium phosphate crystals partly covered with proteinaceous debris were noted on catheter surfaces. Although in some patients encrustation of uric acid occurred in the bladder portion of the stents, there was no uric acid encrustation in this experimental study.

Crystallization↗
PubMed1991

Immunofluorescent study on the interaction between collagen and calcium oxalate crystals in the renal tubules.

The interaction of calcium oxalate crystals and renal tubular cells was studied. Rat renal collecting tubular cells were cultured and immunologically stained with anti-type-IV collagen antiserum (type-IV collagen exists in renal tubular basement membrane). When renal tubular cells and calcium oxalate crystals were mixed, clumps were formed. These clumps were examined by immunological staining with anti-type-IV collagen antiserum. In another series of experiments, calcium-containing crystals were found to be adsorbed onto mucous threads and cast-like materials, although no such adsorption was observed on squamous cells. These absorbed materials interacted with anti-type-IV collagen antiserum. These results suggest that collagen in the renal tubular basement membrane may act as matrix in urinary stone formation.

Animals↗
PubMed1991

Intrarenal hemodynamics in patients with essential hypertension.

Intrarenal hemodynamics were estimated clinically in essential hypertension. Two-week studies were performed in 30 patients with essential hypertension who were given a regular sodium diet in the first week and a sodium-restricted diet in the second week. Intrarenal hemodynamic parameters such as afferent arteriolar (preglomerular) resistance, efferent arteriolar resistance, and glomerular hydrostatic pressure were calculated from renal clearances and plasma total protein concentration measured on the last day of the regular sodium diet. Calculations were based on Gomez's equations with the assumption that the gross filtration coefficient of glomerular capillaries was normal. The increase in afferent arteriolar resistance (8,100 +/- 500 dyne.sec.cm-5) was significantly correlated with an elevation in mean arterial pressure (120 +/- 2 mm Hg), whereas glomerular pressure (56 +/- 1 mm Hg) and efferent arteriolar resistance (2,500 +/- 100 dyne.sec.cm-5) remained normal. The renal function curve (pressure-natriuresis relation) was drawn by plotting urinary sodium excretion on the y axis as a function of mean arterial pressure on the x axis, both of which were measured on the last 3 days of each week. The extrapolated x intercept (107 +/- 2 mm Hg) of the renal function curve was strongly correlated in a 1:1 fashion with the sum of the arterial pressure drop from the aorta to the renal glomeruli plus the opposing pressures against glomerular filtration at glomeruli (r = 0.7, p less than 0.001) on the regular sodium diet, suggesting that the difference between mean arterial pressure on the regular sodium diet and the extrapolated x intercept represented the effective filtration pressure across the glomerular capillaries on the regular sodium diet.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

[Clinical study of extracorporeal shock wave lithotripsy for stones in solitary kidney].

Extracorporeal shock wave lithotripsy (ESWL) treatment was performed on 17 patients with a solitary or sole functioning kidney from August 1986 to April 1988. Some patients with renal stone had a double pig tail catheter to protect the stone street and those with ureteral stones had a ureteral balloon occlusion catheter to raise the efficiency of fragmentation placed prior to ESWL as much as possible. Combined manipulation with such an instrument as nephrostomy tube to wash out residual stone fragments or endoscopic operation were performed. Despite of these devices, ESWL treatments for staghorn calculi and cystine stones were troublesome in solitary kidneys. After follow up ranged from 9 to 602 days (mean 87.6 days), 10 patients (58.8%) were stone free. ESWL treatment is safe and effective for solitary kidneys. We recommended premedication and pretreatment by ureteral stenting in patients with a solitary kidney.

Adult↗
PubMed1991

[Studies on the multiple-drug induction immunosuppressive therapies with cyclosporine after renal transplantation].

Our induction immunosuppressive therapies were carried out on patients split into three groups. The first group of 25 recipients were treated with regimen I [cyclosporin (CsA); 12 mg/kg/day and prednisolone (Pred)]. The second group of 16 recipients were treated with regimen II [CsA; 6 mg/kg/day, Pred and mizoribine (MIZ) or azathioprine (AZA)]. The third group of 14 recipients were treated with regimen III [CsA; 10 mg/kg/day, Pred and MIZ or AZA]. There was no significant difference among the three groups in renal function three months after renal transplantation. The frequency and grade of rejection were significantly higher in Group II than in the other groups. One of group I had CsA nephrotoxicity and none of group III had liver dysfunction three months after renal transplantation. Group I had a higher incidence of posttransplant hypertension. Hypertension of group I was very severe. We concluded that the triple-drug therapy on group III was the best induction immunosuppressive therapy after renal transplantation of the above three.

Adult↗