PubMed Health⌕ Search

Biomedical subjects

K Steven

Publications and source records attributed to K Steven.

At least 73 records · Page 4Linked to original sources
PubMed1986

Transpubic cystectomy and ileocecal bladder replacement after preoperative radiotherapy for bladder cancer.

Radical cystectomy was modified by leaving the apical prostatic capsule to facilitate anastomosis of the isolated ileocecal segment to the urethra and to preserve erectile potency. The transpubic approach was used to increase the exposure, and to facilitate dissection and anastomosis. A total of 15 patients with stages T1 to T4 bladder tumors underwent the operation: 13 after preoperative radiotherapy with 4,000 rad and 2 had salvage cystectomy after 6,000 rad. One patient died postoperatively. The remaining 14 patients underwent urodynamic evaluation 3 to 6 months postoperatively. The maximum urine flow rates were almost normal and none of the patients had significant residual urine. Daytime urinary continence was satisfactory in 13 patients and 1 was moderately incontinent. All of the patients were incontinent at night, probably owing to peristaltic contractions in the intestinal bladder and relaxation of the pelvic floor muscles. Preoperatively, 8 patients experienced erections and 7 had intercourse. Postoperatively, erectile potency was preserved in 4 patients and 3 had sexual function. No orthopedic disability occurred postoperatively. The median followup was 20 months, with a range of 3 to 30 months. There have been no local recurrences. A year postoperatively 6 of 9 patients had sterile urine. This technique makes it possible to avoid a urinary stoma, to obtain satisfactory voiding and urinary continence in almost all cases, and to preserve sexual function in some patients after cystectomy.

Aged↗
PubMed1986

Effects of indomethacin on glomerular hemodynamics in experimental diabetes.

The glomerular hemodynamics were studied in streptozotocin diabetic rats 3 months after the induction and in age-matched normal animals. Indomethacin infusion failed to cause changes in glomerular hemodynamics in normal rats but produced striking effects in the diabetic rats: The afferent arteriolar hydraulic resistance increased substantially while the efferent resistance rose moderately causing large reductions in single nephron blood flow and in the hydraulic pressure in the glomerular capillaries. Consequently, single nephron glomerular filtration rate (SNGFR) was reduced significantly below normal. The ultrafiltration coefficient of the glomerular membrane was significantly lower in the diabetic than in the normal animals (2.8 versus 5.0 nl min-1 mm Hg-1) and remained unchanged during indomethacin infusion. Our results suggest that the prostaglandin system compensates for the changes in the glomerular hemodynamics induced by diabetes by reducing the arteriolar resistances to increase the glomerular capillary pressure making it possible to maintain normal values of SNGFR and nephron blood flow.

Animals↗
PubMed1986

The use of the Boari-flap and psoas-bladder hitch technique in the repair of a high ureteric lesion. A case report.

Combining the bladder-psoas hitch Boari-flap technique makes it possible to replace the entire ureter. The operation was used successfully in one patient with an extensive proximal ureter lesion. This method can be used in patients with reduced renal function, since the continuity of the urinary tract is preserved; it requires a normal bladder wall and bladder capacity exceeding 400 ml.

Female↗
PubMed1986

Activation of killer cells from blood of urinary bladder carcinoma patients by short-term treatment with recombinant interleukin 2.

Highly purified recombinant human interleukin 2 induced cytotoxicity of lymphocytes from urinary bladder carcinoma patients and from control healthy donors when added during an 18-h 51Cr microcytotoxicity assay against bladder carcinoma (T24) target cells. Similar levels of killer cell activation were detected in mononuclear cell preparations from bladder carcinoma patients and control healthy donors; hence, no defect in the responsiveness of bladder carcinoma patients' lymphocytes to interleukin 2 could be observed. The effect of the recombinant interleukin 2 was dose-dependent. Addition of monoclonal antibody 7E9 directed against cell-type restricted antigen associated with the T24 target cells and capable of inducing antibody-dependent cellular cytotoxicity could not increase the cytotoxicity-inducing effects of interleukin 2.

Antibodies, Monoclonal↗
PubMed1984

Evaluation of the micropuncture determination of single nephron filtration fraction.

Spontaneous and aspirated blood samples were collected from the welling points of surface efferent arterioles in the rat kidney. The amount of tubular reabsorbate in each sample was calculated from measurements of the inulin concentration in the sample and systemic arterial plasma. Both spontaneous and aspirated samples contained substantial amounts of tubular reabsorbate (4% +/- 1% and 11% +/- 1%, respectively). Accordingly, the single nephron filtration fraction values derived from measurements of albumin concentrations alone were significantly lower than those calculated considering the addition of the amount of tubular reabsorbate in each sample (0.26 +/- 0.01 vs. 0.30 +/- 0.01 and 0.25 +/- 0.01 vs. 0.34 +/- 0.01 for the spontaneous and aspirated samples, respectively). Increasing the rate of blood collection from the welling point by aspiration was associated with a significant decrease in the hydraulic pressure in the same vessel. The efferent arteriolar blood samples were therefore probably contaminated with tubular reabsorbate as a result of retrograde flow from the peritubular capillaries. It was confirmed that single nephron filtration fractions derived from hematocrit measurements were significantly higher than those based on albumin concentration measurements, supporting that the hematocrit of afferent arteriolar blood of the superficial nephrons is higher than that of systemic arterial blood.

Animals↗
PubMed1982

A model study of the tubuloglomerular feedback mechanism: effector site and influence on renal autoregulation.

The effector site of the macula densa tubuloglomerular feedback mechanism was determined with a mathematical model of glomerular ultrafiltration. The feedback response was found to be mediated by an increase in the hydraulic resistance of the afferent arteriole, possibly accompanied by a slight decrease in the ultrafiltration coefficient of the glomerular membrane. The contribution of the tubuloglomerular feedback mechanism to the autoregulation of renal blood flow and GFR during increased arterial blood pressure was evaluated with a mathematical model of the kidney. The tubuloglomerular feedback system of the superficial nephron was found to be a less efficient regulator of renal blood flow and GFR than the remainder of the autoregulatory mechanism.

Feedback↗
PubMed1981

A case with severe diarrhoea and Strongyloides stercoralis infection.

A case with severe diarrhoea and Strongyloides stercoralis infection is described. Further examination showed that the patient also had abnormal colonization of the duodenum with Hafnia alvei and that this disappeared when the Strongyloides infection was treated with mebendazole. Symptoms such as abdominal pain, diarrhoea, "skin rash" and malabsorption in association with blood eosinophilia should arouse suspicion of strongyloidiasis.

Adult↗
PubMed1981

A mathematical model of fluid transport in the kidney.

A mathematical model of the rat kidney is developed from glomerular and tubular submodels. It is assumed that all nephrons are identical, that the hydraulic pressure in the tubules obeys Hagen-Poiseuille's law, that the rate of fluid reabsorption depends on the flow rate of tubular fluid, and that the tubules are distensible. The independent variables of the model are selected to comply with experimental measurements in the hydropenic rat. The model is used to evaluate the mechanism of glomerulotubular balance: changing the mean ultrafiltration pressure to the glomerular capillaries has a substantial influence on glomerular filtration rate (GFR). A change in the rate of fluid reabsorption in the proximal tubules has a strong influence on GFR notwithstanding that the change in GFR is smaller than that in the rate of fluid reabsorption. The calculated values for the hydraulic pressure profile in the tubular system and the interstitial pressure during ureteral obstruction are in close agreement with experimental measurements. Increasing the arterial haematocrit above normal causes a substantial decrease in GFR, whilst reducing it below normal has only a small effect on GRF.

Animals↗
PubMed1981

Prostaglandin E2-mediated secretory diarrhea in villous adenoma of rectum: effect of treatment with indomethacin.

Biochemical and clinical evidence is presented to indicate that prostaglandin (PG)E2 is the mediator of fluid and electrolyte secretion by villous adenomas of the rectum. A 64-yr-old man with a 2-mo history of mucous diarrhea had, on admission, prerenal uremia, severe hyponatremia, and hypokalemia. At sigmoidoscopy an 11 X 11-cm villous adenoma of the rectum was revealed. The rectal fluid discharge was 1800-1825 ml/day, with sodium and potassium concentrations of 150 and 12 mEq/L, respectively. Immunoreactive PGE2 levels in the rectal effluents were high (viz. 1160-1250 pg/ml vs. 200-395 pg/ml) compared with those in stool water from patients with infectious diarrhea. The concentration of vasoactive intestinal polypeptide (VIP) in the tumor was lower (viz. 10.5 pmol/g vs. 100-700 pmol/g) than in normal colonic mucosa. Indomethacin treatment (24 mg X 4 daily) reduced the rectal PGE2 excretion from 2.2 to 0.3 microgram/day and caused a decrease in the rectal fluid loss of 850 ml/day associated with a similar reduction in rectal sodium excretion. Discontinuing medication, a rise in the rectal excretions of PGE2, fluid, and sodium was observed. In conclusion, PGE2 formation in the villous adenoma appears to be the cause of fluid secretion by the abnormal tumor epithelium. The use of PG synthetase inhibitors may facilitate the preoperative correction of severe fluid-electrolyte deficits in patients with large villous adenomas of the rectum.

Adenoma↗
PubMed1981

Renal function in streptozotocin-diabetic rats.

Renal function was examined with micropuncture methods in the insulin-treated streptozotocin-diabetic rat. Kidney glomerular filtration rate was significantly higher in the diabetic rats (1.21 ml/min) than in the control group (0.84 ml/min) Nephron glomerular filtration rate increased in proportion to the rise in kidney glomerular filtration rate (diabetic rats: 37.0 nl/min; control rats: 27.9 nl/min). Likewise renal plasma flow was significantly higher in the diabetic rats (4.1 ml/min) than in the control group (3.0 ml/min). Glomerular capillary pressure was identical in both groups (56.0 and 56.0 mmHg, respectively). The proximal intratubular pressure was significantly reduced in the diabetic rats (10.4 mmHg; control value: 12.5 mmHg). The effective glomerular ultrafiltration coefficient was slightly but not significantly higher in the diabetic rats (0.027 nl s-1mmHg-1) than in the control group (0.023 nl s-1mmHg-1). Kidney weight was significantly higher in the diabetic rats (1.15 g; control rats: 0.96 g) while body weight was similar in both groups (diabetic rats: 232 g; control rats: 238 g). Calculations indicate that the increases in transglomerular hydraulic pressure, renal plasma flow and ultrafiltration coefficient of the glomerular membrane contribute about equally to the rise in glomerular filtration rate. The increases in the values of the determinants of glomerular filtration rate may be the result of renal hypertrophy. These studies suggest that this model provides a useful method for investigating kidney function in diabetes, which may have relevance for our understanding of the kidney abnormalities in human diabetes.

Animals↗
PubMed1980

Influence of orchidopexy for cryptorchidism on subsequent fertility.

The concentration of spermatozoa in ejaculate from testes that had been subjected to orchidopexy during childhood was studied in semen samples taken after unilateral vasectomy of the contralateral normal testis in 4 patients. The counts were extremely low, which suggests that this operation does not improve fertility later in life. Sperm concentration is not influenced by unilateral vasectomy or by inguinal herniotomy during childhood.

Adult↗
PubMed1979

Influence of intratubular pressure on proximal tubular compliance and capillary diameter in the rat kidney.

Tubular compliance is the response of tubular diameter to changes in intratubular pressure [7]. Proximal tubular compliance was determined directly by measurements of tubular diameter and pressure and indirectly using a mathematical model of tubular fluid flow based on measurements of the hydraulic pressure gradients along the tubule under free flow conditions and during an induced pressure reduction at the end of the proximal tubule. The two independent methods yielded similar values for compliance. Proximal tubular compliance was found to depend upon the intratubular pressure: tubular compliance was significantly higher (P less than 0.001) when the intratubular pressure was reduced below normal (1.0 micron cm H2O-1) than when the pressure was increased above the control value (0.4 micron cm H2O-1). Almost identical compliance values were measured in sodium pentobarbital and inactin anaesthetized rats (P greater than 0.8). Intratubularpressure changes resulted in inverse changes in the diameters of the adjacent capillaries, suggesting that the peritubular capillaries are distensible structures.

Animals↗