Pathophysiology of obstructive nephropathy.
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Angiotensin II↗
Biomedical subjects
D R Wilson
Publications and source records attributed to D R Wilson.
Lack of effect of chronic renal denervation on altered sodium reabsorption during increased ureteral pressure.
The role of the renal nerves in the altered sodium reabsorption which occurs during increased ureteral pressure was studied using clearance techniques in anaesthetized rats undergoing diuresis induced by isotonic saline infusion. In rats with a sham denervated kidney, an ipsilateral increase in ureteral pressure to 20 cm H2O resulted in a marked and significant decrease in sodium and water excretion, increased fractional sodium reabsorption, and increased urine osmolality with no significant change in glomerular filtration rate. A similar significant ipsilateral increase in tubular reabsorption of sodium occurred in rats with chronically denervated kidneys during increased ureteral pressure. The changes in tubular reabsorption were rapidly reversible after return of ureteral pressure to normal. These experiments indicate that enhanced tubular reabsorption of sodium during an ipsilateral increase in ureteral pressure is not mediated by increased renal nerve activity. During the antinatriuresis of increased ureteral pressure there was a decrease in the fractional reabsorption of sodium from the opposite normal kidney. The role of the renal nerves in this compensatory change in function in the opposite kidney was studied in two further groups of animals. The renal response to a contralateral increase in ureteral pressure was similar in denervated and sham-denervated kidneys. The results indicate that altered renal nerve activity, through ipsilateral or contralateral renorenal reflexes, is not responsible for the changes in tubular reabsorption of sodium which occur during increased ureteral pressure induced by partial ureteral obstruction.
Absorption↗
Transepidermal water loss in vivo. Premature and term infants.
In vivo, noninvasive, transepidermal water loss measurements were taken from 26- to 41-week gestational age infants with a Meeco electrolytic water analyzer to yield information on the development of the function of the skin barrier. Infants 28 weeks or less have significantly greater transepidermal water loss than older gestational aged infants, thus indicating a less efficient barrier to water. Until it is known whether the decreased barrier function in premature infants also relates to percutaneous penetration, prudence is suggested in exposing such premature infants skin to chemicals.
Body Water↗
The feasibility of using a Canadian examination for the certification of Australasian candidates in psychiatry.
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Australia↗
Boerhaave syndrome: lifters' liability.
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Aged↗
Dialysis for renal failure in Toronto.
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Ambulatory Care↗
Idiopathic calcium nephrolithiasis. 1. Differences in urine crystalloids, urine saturation with brushite and urine inhibitors of calcification between persons with and persons without recurrent kidney stone formation.
The propensity of urine to promote calcium stone formation was compared in 64 patients with recurrent idiopathic calcium nephrolithiasis and 30 healthy individuals without such a history. The rates of excretion of urine crystalloids, the urine saturation with brushite (CaHPO4-2H2O), the ability of the urine to calcify collagen in vitro, and the concentration of urine inhibitors of collagen calcification were measured. The patients had a reduced urine citrate excretion rate in addition to an increased urine calcium excretion rate, while the rates for urine magnesium, phosphate, uric acid and oxalate were not significantly different in the two groups of subjects. The urine concentration of magnesium, phosphate and uric acid was decreased in the patients because of the higher urine volume. The urine creatinine excretion rate correlated with the rates of excretion of urine calcium, magnesium, phosphate, uric acid and oxalate in both groups, which suggested that increased lean body mass, possibly associated with greater food intake, may be an important determinant of crystalloid excretion. The urine of the patients was significantly more saturated with brushite than the urine of the control subjects and resulted in greater collagen calcification when incubated in vitro. The urine concentration of inhibitors of collagen calcification, however, was not significantly different in the two groups. Thus, the urine of patients with recurrent idiopathic calcium nephrolithiasis is more highly saturated with brushite, largely as a result of an increased urine calcium excretion rate, and contains a lower concentration of magnesium and citrate, substances that tend to prevent the precipitation and growth of crystals in urine.
Adult↗
Idiopathic calcium nephrolithiasis. 2. Differences between hypercalciuric and normocalciuric persons with recurrent kidney stone formation and persons without such a history.
Normocalciuric and hypercalciuric patients with idiopathic recurrent calcium nephrolithiasis were compared with healthy individuals without such a history to examine the factors that predispose normocalciuric patients to stone formation. The urine calcium excretion rate was higher in the normocalciuric patients than in the control subjects (227 v. 183 mg/24 h; P less than 0.01), but the urine calcium concentration was not significantly different. The urine magnesium and citrate excretion rates and concentrations were lower in the normocalciuric patients than in the control subjects (P less than 0.001), while the urine uric acid and oxalate excretion rates and concentrations and the urine saturation with brushite (CaHPO4-2H2O) were not significantly different. These results suggest the importance of slight increases in the urine calcium excretion rate together with decreased urine magnesium and citrate excretion rates in normocalciuric persons with recurrent calcium stone formation. The urine of the hypercalciuric patients was more highly saturated with brushite than the urine of the normocalciuric patients and the control subjects, and the excretion rates of uric acid and oxalate were increased in the hypercalciuric patients. The hypercalciuric patients had a higher urine creatinine excretion rate than the normocalciuric patients and a higher daily urine volume than the control subjects, which suggests that differences in lean body mass or fluid and food intake, or both, may be important determinants of these differences in crystalloid excretion. As in the normocalciuric patients, the urine citrate excretion rate and concentration were decreased in the hypercalciuric patients compared with the control subjects.
Adult↗
Phosphorylative respiratory activity of mitochondria isolated from the left and right ventricles of rabbit hearts following partial pulmonary trunk occlusion.
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Animals↗
Medullary collecting duct function in the remnant kidney before and after volume expansion.
The role of the medullary collecting ducts (CD) in the regulation of water and electrolyte excretion by the remnant kidney has not been determined. Medullary CD function was therefore studied by the microcatheterization technique during hydropenia and after volume expansion with an isotonic saline load in rats with sham-operated normal kidney (stage I), remnant kidney (stage II), remnant kidney after contralateral nephrectomy (stage III), and sham-operated normal kidney after contralateral nephrectomy (stage-III control). Sodium, potassium, water, and solute reabsorption along the medullary CD were not altered in stage II during hydropenia when compared to normal control (stage I), but water reabsorption proximal to the medullary CD was decreased. In stage III, where the uremia was mild (BUN, 41 mg/dl), the fractions of the filtered load of sodium (72%) and water (62%) which were reabsorbed along the medullary CD were reduced in comparison to stage II (94% and 83%, respectively), stage I, or stage-III control. The fraction of filtered potassium entering the medullary CD was increased to 53% in stage III, compared to 16% in stage II, and 10 or 11% in stage I or stage-III control. No change in the fraction of filtered potassium remaining along the collecting ducts was observed. After volume expansion, there was no significant change in the fraction of filtered sodium and water remaining along the medullary CD in stage I, II, or III. The greater fractional excretion in stage III resulted from decreased reabsorption in more proximal nephron segments. The results indicate that (a) during hydropenia, fractional reabsorption of sodium and water is decreased along the medullary CD of the stage-III remnant kidney in the presence of mild uremia, (b) the increased fractional excretion of potassium in the remnant kidney with uremia is not determined by altered potassium handling in the medullary CD but occurs proximal to this nephron segment, and (c) extracellular fluid volume expansion with isotonic saline results in similar inhibition of fractional sodium and water reabsorption in the collecting ducts of both remnant and normal kidneys.
Animals↗
Initial experiences with continuous ambulatory peritoneal dialysis.
Continuous ambulatory peritoneal dialysis (CAPD) has been initiated on 51 patients: 27 females (mean age -- 43.9 years) and 24 males (mean age -- 46.4 years). This group has been observed for a total of 1420 patient weeks of treatment (27.3 patient years). Thirty-six episodes of peritonitis have been noted among 19 patients. The overall incidence was one episode per 39.4 patient weeks. Recurrent episodes of peritonitis resulted in discontinuation of CAPD in five (9.8%) of the patients. Three (5.9%) of the patients were unable to continue with CAPD because of its inability to control extracellular fluid balance. In the patients who transferred from intermittent peritoneal dialysis to CAPD, there was a 4.5 mg/dl drop in serum creatinine and a 34 mg/dl drop in mean BUN values. There was a rise of approximately 2 gm in the hemoglobin levels of this group of patients. If the problem of peritonitis can be solved, CAPD will become the dialytic treatment of choice for the majority of patients with end-stage renal disease.
Adult↗
Circulating natriuretic and kaliuretic factors in acute uremia: the role of the kidney.
The role of the kidney as a source or as the excretory route for natriuretic and kaliuretic factors present in acute uremia was studied using the technique of isovolemic cross-circulation in 49 pairs (eight groups) of anaesthetized rats. Marked and similar natriuresis, kaliuresis, and diuresis occurred in recipients undergoing cross-circulation with donors subjected to either bilateral nephrectomy or total intravenous urine reinfusion for 18 h previously, and were not seen with sham-operated donors. Similar and significant, but less marked, changes occurred in two groups with bilateral nephrectomy or urine reinfusion of only 3 h duration. Urea-loaded normal donors caused a natriuresis and kaliuresis which was similar to the two 18-h uremic donor groups. When donor animals were sodium depleted prior to bilateral nephrectomy the natriuretic response in the recipients was significantly reduced. The results indicate that the kidney is not necessary for the rapid appearance of natriuretic and kaliuretic activity in the blood of acutely uremic animals, and that such activity results from the retention of factors of extrarenal origin. Natriuresis and kaliuresis result from inhibition of tubular reabsorption and are not dependent on changes in glomerular filtration or renal hemodynamics. Pitressin or aldosterone levels. Urea appears to be a major component of the circulating natriuretic and kaliuretic activity in acute uremia but evidence of other factors was also obtained.
Acute Disease↗
Effect of acute and chronic renal denervation on renal function after release of unilateral ureteral obstruction in the rat.
The role of the renal nerves in determining renal function after relief of 24-h unilateral ureteral obstruction (UUO) was studied using clearance techniques in anaesthetized rats. Acute renal denervation during the first 1--2 h after relief of UUO resulted in a significant increase in glomerular filtration rate (GFR), renal plasma flow (RPF), urine flow, and sodium and potassium excretion, changes which were not seen in the sham-denervated postobstructive kidney. Acute denervation of sham-operated normal kidneys caused a similar natriuresis and diuresis but with no change in GFR or RPF. Chronic renal denervation 4--5 days before UUO denervated postobstructive controls, while chronic denervation alone was associated with a significantly higher urine flow and sodium excretion rate from the denervated kidney. The effectiveness of renal denervation was confirmed by demonstrating marked depletion of tissue catecholamines in the denervated kidney. It was concluded that renal nerve activity plays a significant but not a major role in the functional changes present after relief of UUO. Chronic renal denervation did not protect against the functional effects of unilateral ureteral obstruction.
Animals↗
Hyperlipidemia after renal transplantation: natural history and pathophysiology.
Twenty-five patients had their lipid profile monitored sequentially for up to 3 years post-transplant. All patients had a good graft function throughout the study. Forty-four percent remained hypertriglyceridemic. The lipid level was not due to diet or excessive weight gain. Triglyceride turnover studies showed that overproduction was the predominant defect in patients receiving massive steroids to reverse rejection and in stable long-term recipients. Repeat metabolic investigations in the latter group, after changing to alternate-day, equal-dose steroid therapy showed improvement in both the absolute triglyceride concentration and the triglyceride production rate. The correlation observed between basal insulin level and triglyceride concentration suggests the drug may act through this hormone, stimulating hepatic triglyceride production. A change to alternate-day steroid therapy should be considered in post-transplant patients who are hyperlipemic while receiving minimal daily prednisone therapy.
Adult↗
Abdominal aortic aneurysms: recent experience with 210 patients.
In the 6 1/2 years ending June 1977, 210 patients with abdominal aortic aneurysms underwent operation at Toronto Western Hospital; 160 aneurysms (76%) were unruptured and 50 (24%) were ruptured. In the patients with unruptured aneurysms the mean age was 68 years; the oldest was 91, and 12 were more than 80 years of age. The overall hospital mortality was 5.6%. Death in hospital occurred in 1 (1.2%) of the 83 asymptomatic patients, 4 (7.4%) of the 54 symptomatic patients and 4 (17.0%) of the 23 patients for whom operation was considered urgent. In the patients with ruptured aneurysms the mean age was 71 years; the oldest was 90, and five were more than 80 years of age. The overall hospital mortality was 54%. The morbidity and mortality were analysed; in particular the reasons for the markedly variable hazard of operations for the three categories of unruptured aneurysm were sought. The surgical literature is confusing because of the interchanging use of the words unruptured, elective and symptomless. The current philosophy management and technique of operation in a large cardiovascular surgery service with many trainees are presented and a plea is made for a standardized and simplified operation, always performed with three assistants helping the operating surgeon.
Aged↗
Effect of hydrochlorothiazide on urine saturation with brushite, in vitro collagen calcification by urine, and urinary inhibitors of collagen calcification.
To clarify further the beneficial effect of thiazide diuretics on recurrent calcium nephrolithiasis, the effect of short-term hydrochlorothiazide therapy on urine saturation with brushite (CaHPO(4).2H(2)O), in vitro collagen calcification by urine, and urinary inhibitors of calcification was studied.In 22 patients with idiopathic calcium oxalate/phosphate stones the urine calcium excretion decreased, the urine magnesium excretion increased and the urine magnesium/calcium ratio increased significantly (P < 0.001) during hydrochlorothiazide therapy. Supersaturation of the urine with brushite, which was present in 19 of the 22 patients, was reduced significantly (P < 0.001) in all during thiazide therapy, and to the undersaturated range in 16. The ability of urine to calcify collagen in vitro also decreased significantly (P < 0.001) during thiazide therapy, a change that correlated significantly (r = 0.4513, P < 0.05) with the decrease in brushite saturation. The concentration of urinary inhibitors of calcification, as determined with an in vitro collagen calcification system, was decreased significantly (P < 0.01) by thiazide therapy.It was concluded that, in addition to decreasing urine calcium excretion and increasing urine magnesium excretion, thiazide diuretics decrease the urinary brushite saturation and thus may prevent spontaneous nucleation or crystal growth, or both, of calcium phosphate. The ability of thiazides to decrease collagen calcification in vitro suggests that they may also prevent crystal growth on a nidus of organic matrix. Thiazides do not appear to act by increasing the excretion of urinary inhibitors of calcification.
Adult↗
Calcium metabolism in adult outpatients with epilepsy receiving long-term anticonvulsant therapy.
Long-term anticonvulsant drug therapy may lead to abnormalities of calcium metabolism resulting in osteomalacia. The prevalence and severity of altered calcium metabolism was studied in an adult outpatient population of persons with epilepsy receiving anticonvulsant therapy for a minimum of 2 years. Assessment of calcium metabolism was based on serum concentrations of calcium, phosphorus, alkaline phosphatase and 25-hydroxycholecalciferol and of plasma parathyroid hormone, intestinal absorption of isotopic calcium and skeletal bone mineral mass as determined by in vivo neutron activation or x-ray photodensitometry.Thirty-nine patients who had been receiving anticonvulsant therapy for an average of 20 years were studied; none had clinical evidence of metabolic bone disease. Decreased serum calcium concentration was noted in 10%, decreased serum phosphorus concentration in 10% and elevated serum alkaline phosphatase concentration in 44%. The mean serum 25-hydroxycholecalciferol concentration was significantly lower (P < 0.001) than in a control group (11.6 v. 19.6 mg/mL). None of 18 patients studied had an increased plasma concentration of parathyroid hormone, and only 1 of 17 patients had decreased intestinal absorption of isotopic calcium. Bone mineral mass was decreased in 44% of 32 patients studied.It was concluded that long-term treatment with anticonvulsant drugs leads to mild abnormalities of calcium metabolism and decreased bone mineral mass in a substantial percentage of adult outpatients with epilepsy. These abnormalities probably predispose the patients to the development of clinically significant metabolic bone disease.
Adult↗
Studies in inhibitors of calcification and levels of urine saturation with calcium salts in recurrent stone patients.
Studies have been done on patients with recurrent renal calculous disease, measuring in addition to the usual serum and urine constituents the inhibiting capacity of the urine and the activity products of calcium oxalate, octocalcium phosphate and brushite. Studies on the 24-hour urine calcium, phosphorus and uric acid and serum calcium indicate no essential differences between patients with calcium oxalate, mixed or uric acid stones and normal individuals. We were unable to demonstrate a difference in the inhibiting capacity of the urine between normal individuals and patients with calcium oxalate calculi, and levels of saturation of urine with calcium oxalate were identical in the calcium oxalate stone patients and normal individuals. The degree of saturation of urine with calcium phosphate is significantly greater in stone patients.
Calcification, Physiologic↗