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Biomedical subjects

K C Bovee

Publications and source records attributed to K C Bovee.

At least 19 recordsLinked to original sources
PubMed1992

Membrane fluidity and sodium transport by renal membranes from dogs with spontaneous idiopathic Fanconi syndrome.

To comprehend the renal defect underlying the idiopathic Fanconi syndrome in the Basenji dog, we have used isolated renal brush border membrane vesicles to examine two factors that influence membrane nonelectrolyte transport processes, sodium flux and membrane fluidity. We have found that there is no significant difference in the rate of uptake of 100 mmol/L 22Na+ and conclude that the previously observed defects in the sodium gradient-stimulated overshoot of glucose and of proline are not related to an alteration in the flux of sodium at physiological concentrations. Since carrier proteins exist in a lipid milieu, alteration in the physical state of the lipid membrane can determine transport function. Renal brush border preparations from normal and affected animals were studied by measuring fluorescence polarization to assess differences in the physical state of the membranes using the fluorescent probe, DPH, which quantitates inner core membrane fluidity. Membranes from affected dogs consistently showed a higher fluidity as measured by eta, a parameter of DPH fluorescence polarization. Since membrane fluidity is related to lipid composition, the data suggest that there may be an important alteration in the lipids in renal membranes of affected animals.

Animals↗
PubMed1991

Cholecalciferol rodenticide intoxication in a cat.

A 4-month-old 2.5-kg sexually intact female domestic shorthair cat was referred to the teaching hospital because of suspected cholecalciferol intoxication after ingestion of a cholecalciferol-containing rodenticide. At referral, the cat was hypercalcemic, hyperkalemic, and acidotic. Despite management of hypercalcemia and preservation of renal function with physiologic saline solution, furosemide, dopamine, and calcitonin, the cat died, apparently as a result of extensive pulmonary mineralization.

Animals↗
PubMed1991

Effects of the nonpeptide angiotensin II receptor antagonist DuP 753 on blood pressure and renal functions in spontaneously hypertensive PH dogs.

A colony of genetic hypertensive dogs with systolic blood pressure of 140 to 220 mm Hg and diastolic blood pressure greater than 100 mm Hg in the trained state was used. The objective of this study was to investigate the hemodynamic and renal effects of the novel angiotensin II receptor antagonist DuP 753 given intravenously to these dogs. Renal functions and blood pressure were measured 45 to 75 min after the intravenous administration of DuP 753 at 1, 3, 10, and 30 mg/kg and were compared to control (placebo) treatment. Arterial pressure was slightly but significantly and dose-dependently reduced by DuP 753. Glomerular filtration rate increased significantly in a dose-dependent manner. Similarly, effective renal plasma flow was dose-dependently increased. Filtration fraction was unchanged. Renal vascular resistance was significantly reduced in a dose-dependent manner at 3, 10, and 30 mg/kg of DuP 753. DuP 753 increased fractional sodium excretion at all doses and increased fractional potassium excretion only at the highest doses. The vasopressor effects of angiotensin I and II were dose-dependently inhibited by DuP 753. These data show that DuP 753 has beneficial renal hemodynamic effects and lowers arterial pressure in this canine model of essential hypertension.

Angiotensin Receptor Antagonists↗
PubMed1989

Essential hypertension in a dog.

Severe hypertension was diagnosed in a dog that initially was referred for evaluation of visual deficits and retinal hemorrhage and eventually was donated for medical treatment of hypertension. Initial blood pressure measured by direct methods was markedly high (systolic, 275 mm of Hg; diastolic, 170 mm of Hg). Measures of renal function were within normal limits, with the exception of hypotonic urine. A test protocol was designed to exclude possible secondary causes of hypertension; negative results of such tests allowed the diagnosis of essential hypertension. The consistency of the hypertension and its response to medical control were studied for 5 years. Blood pressure while the dog was untreated during those years was 240 +/- 24 mm of Hg (systolic) and 146 +/- 14 mm of Hg (diastolic). Plasma renin activity was within normal limits, and the response of the renin-angiotensin system to varied salt intake was normal. The most effective medications used to lower blood pressure were propranolol and captopril, both of which were more effective than salt restriction alone. Five years after the diagnosis of hypertension, the dog was euthanatized because of chronic renal failure secondary to pyelonephritis. Hypertension was less severe as the condition progressed into chronic renal failure. Complete necropsy did not reveal an obvious cause of the hypertension, and histopathologic changes were limited to the cardiovascular system, eyes, and kidneys.

Animals↗
PubMed1989

Cystinuria in dogs: comparison of the cystinuric component of the Fanconi syndrome in basenji dogs to isolated cystinuria.

Two animal models for cystinuria have been examined: the Basenji dog with Fanconi syndrome and cystine stone-forming dogs of various breeds. Brush-border membranes were isolated from these animals and uptake of D-glucose and L-cystine was characterized. Experiments with isolated brush-border vesicles from Basenji dogs with cystinuria as a component of the Fanconi syndrome showed diminished sodium-dependent D-glucose uptake but no decrease in L-cystine uptake even though the cystine defect in vivo was as high as 94% (ie, 6% reabsorption). In contrast, brush-border vesicles isolated from the kidney of a cystine stone-forming dog (Welsh Corgi) with a cystine defect of only 16% (ie, 84% reabsorption) had decreased uptake of cystine compared to values found for Beagle and Basenji vesicles. Thus, cystinuria found in Basenji dogs with the Fanconi syndrome differs from that in classic stone-forming cystinuric dogs. The alteration responsible for the cystinuria of Basenji dogs with Fanconi syndrome does not appear to have a membrane locus and may reflect altered energetics for transport, which are not detected in isolated vesicles. The cystine defect in cystinuric stone-forming dogs does appear to be reflected in the isolated membrane.

Amino Acids↗
PubMed1987

Hypertension and renal function.

The presence of hypertension in domestic animals is poorly described. Values for hypertension were established in dogs using a direct blood pressure measurement. A protocol was devised to recognize and characterize primary (essential) and secondary hypertension. Essential hypertension was associated with marked elevations in blood pressure and can be shown to be a hereditary disease in dogs. Secondary hypertension is more common and most frequently associated with Cushing's disease and renal failure. Treatment to reduce blood pressure in both groups can be achieved using pharmacologic agents which are more effective than sodium restriction alone. Hypertension appears to be an underdiagnosed disease in dogs. The significance of chronic hypertension in dogs in terms of vascular pathology is not yet clear.

Animals↗
PubMed1986

Long-term renal responses to high dietary protein in dogs with 75% nephrectomy.

It has been proposed that ingestion of large amounts of dietary protein leads to sustained renal hyperperfusion and progressive glomerulosclerosis in rats. This hypothesis was tested in dogs, with 75% reduction in renal mass, maintained for 4 years on either 56, 27, or 19% dietary protein. Twelve of 21 dogs survived 4 years, and death due to renal failure was not correlated to diet. Dogs fed 56 and 27% protein had increased GFR and CPAH before and after reduction of renal mass compared to the 19% group. A pattern of deterioration of renal function, including proteinuria, was not found in any diet group. Nine of 11 dogs, fed 56, 27, or 19% protein had minimal glomerular lesions, including mesangial proliferation, GBM irregularities, adhesions, and sclerosis. Two other dogs, fed 56% protein, had more severe glomerular lesions. No significant ultrastructural differences were found in glomeruli among the three diet groups. These results do not support the hypothesis that high protein feeding had a significant adverse effect on either renal function of morphology in dogs with 75% nephrectomy.

Animals↗
PubMed1986

Renal function and laboratory evaluation.

This paper reviews the normal renal function in relation to common functional tests helpful to detect nephrotoxicity. The measurement of renal blood flow, intrarenal distribution of blood flow, and glomerular filtration rate remain the basic parameters of nephrotoxicity. Renal tubular function is accurately measured by standard clearance tests for solutes including electrolytes, glucose and amino acids. The renal concentrating capacity serves as a sensitive but non-specific measure of renal integrity. The measurement of plasma concentration of some solutes is helpful to identify nephrotoxicity, but is most effective when a profile of solutes is measured over a time period. Urinary protein excretion and particularly the excretion of enzymes may localize the nephrotoxicity in certain tubular segments. Due to the multiple functions of the kidney, no single test or group of tests can be relied upon to detect nephrotoxicity. A battery of tests including screening tests and specific tests to measure glomerular or tubular function must be selected to match the pattern of nephrotoxicity.

Amino Acids↗
PubMed1986

Developmental aspects of cystine transport in the dog.

Developmental changes in cystine transport by the canine kidney were examined both in vivo and in vitro. Renal clearance studies indicated that cystine was one of the more incompletely reabsorbed amino acids at birth, but its reabsorption approaches adult levels by 21 days. Concomitantly, cystine uptake by isolated renal cortical tubule fragments from immature dogs was slower than that by renal tubules from adult dogs. Both age groups rapidly metabolized the transported cystine. This metabolism was principally to cysteine, but also small amounts of reduced glutathione were formed from the transported cystine. Concentration dependence studies indicated two transport systems for cystine uptake in both the immature and the adult dog. Both transport systems in the 1-wk-old dog had a somewhat greater affinity for cystine than the corresponding system in the adult, but this was offset by the markedly lower maximal transport rates for these systems in the 1-wk-old dog. The high affinity system was inhibited by lysine in tubules from both age groups. In the dog, the rise in the tubular reabsorption of cystine with maturation could, in part, be explained by an increase in the number of transport sites for cystine.

Animals↗
PubMed1978

Cystinuria in a maned wolf.

A renal calculus composed principally of the amino acid, cystine, was found in an 8-year-old male maned wolf (Chrysocyon brachyurus). Cystine crystals were found in the urine sediment. The renal clearance of 10 amino acids was abnormal, whereas reabsorption of others was normal. The renal clearance of cystine, lysine, ornithine, and arginine exceeded the filtered load. The renal tubular handling of glucose, phosphate, sodium, potassium, and uric acid was identical to that for the clinically normal dog. These findings indicated an isolated renal tubular defect for cystine and other amino acids.

Animals↗
PubMed1978

The fanconi syndrome in Basenji dogs: a new model for renal transport defects.

The renal defects resulting in a Fanconi syndrome were seen in eight Basenji dogs by measuring renal clearance and in vitro amino acid and sugar uptake and performing histopathologic evaluations. Renal tubular handling of glucose, phosphate, sodium, potassium, uric acid, and amino acids was abnormal, and in vitro uptake of labeled lysine, glycine, and alpha-methyl-D-glucoside by renal cortical slices was impaired. Histopathology was normal except for enlarged nuclei in some renal tubule cells. These Basenji dogs, which may be genetically affected, represent a likely model for idiopathic Fanconi syndrome in humans.

Amino Acids↗
PubMed1977

Liquid membrane capsules for treatment of uremia.

The objective of the program is to use ingested liquid membrane capsules (LMC) as gastrointestinal toxin traps as an adjunct to dialysis. Urea has been selected as the model toxic component to study before expanding the technology to other toxins. Transport across the small intestinal mucosa has been indicated to be adequate. There is no indication of reduction of mucosal transport or damage to the intestinal mucosa over short term but repetitive LMC perfusions. Performance of LMC perfused through Thiry Vella small intestinal loops is as good as in vitro performance and can be predicted. Substantial progress has been made toward developing LMC to perform in the more complex environment of the intact gastrointestinal tract. The demonstration of LMC performance in vivo with intact gastrointestinal tracts, and perhaps some increase in rate of toxin removal, will be required before LMC can be considered practical candidates for clinical use.

Administration, Oral↗