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Biomedical subjects

D J Chew

Publications and source records attributed to D J Chew.

At least 37 records · Page 2Linked to original sources
PubMed1997

Effect of sodium bicarbonate administration on renal function of horses.

OBJECTIVE: To describe changes in renal function of horses after oral and i.v. administration of sodium bicarbonate (NaHCO3) and to determine whether changes are dose dependent. ANIMALS: 6 Standardbred mares. PROCEDURE: Blood and urine samples for determination of renal function were collected immediately before and at hourly intervals for 12 hours after administration of each of 3 oral doses (1,500, 1,000 and 250 mg/kg of body weight, in 3 L of water) and 1 i.v. dose (250 mg/kg, 5% solution) of NaHCO3, or water (3 L orally). RESULTS: NaHCO3 induced increases in urine flow; electrolyte-free water reabsorption; urine concentrations of sodium and bicarbonate; fractional excretion of sodium, potassium, chloride, and bicarbonate; urinary excretion and clearance of sodium and bicarbonate; urine pH and anion gap; and mean plasma concentration of antidiuretic hormone. NaHCO3 induced attenuation in reduction with time of urine excretion and clearance of potassium, chloride, and osmoles, and induced reduction in urine osmolality. Plasma aldosterone and atrial natriuretic peptide concentrations and glomerular filtration rate were not modified. CONCLUSIONS: Renal responses to NaHCO3 load emphasize conservation of plasma volume and reestablishment of acid-base balance over control of hyperosmolality by diuresis, natriuresis, and increased bicarbonaturia. These responses imply a large fluid shift from the extravascular space to the vascular compartment, which was eliminated via diuresis, thus preventing hypervolemia.

Acid-Base Equilibrium↗
PubMed1996

Juvenile renal disease in golden retrievers: 12 cases (1984-1994).

OBJECTIVE: To evaluate clinical and pathologic findings in Golden Retrievers with renal dysplasia. DESIGN: Retrospective study. ANIMALS: 12 young Golden Retrievers with chronic renal disease. PROCEDURE: Medical records of affected dogs were evaluated on the basis of clinical findings, laboratory test results, and histologic findings. RESULTS: Common clinical findings were vomiting, anorexia, weight loss, polydipsia, and polyuria. Common laboratory findings were azotemia, hyperphosphatemia, hypercholesterolemia, isosthenuria, proteinuria, hypercalcemia, and nonregenerative anemia. Many affected dogs also had urinary tract infections, and some were hypertensive. Renal lesions consisted of moderate-to-severe interstitial fibrosis and mild-to-moderate lymphoplasmacytic interstitial inflammation. Cystic glomerular atrophy and periglomerular fibrosis were prominent features in most affected dogs. Fetal lobulation of glomeruli, adenomatoid hyperplasia of collecting tubule epithelium, and primitive mesenchymal connective tissue were histologic features suggestive of renal dysplasia. CLINICAL IMPLICATIONS: Renal dysplasia should be suspected in Golden Retrievers < 3 years old with clinical findings and laboratory results indicative of renal disease.

Animals↗
PubMed1996

Intermittent alkaline urine in a cat fed an acidifying diet.

Detection of alkaline urine traditionally sends an alert to the clinician to consider the presence of a urease-producing bacterial urinary tract infection, postprandial alkaline tide, or the ingestion of a diet that is nonacidifying. In the cat of this report, acid urine was produced while the cat was in the home environment, but alkaline urine was produced following the stress of a long trip to the veterinarian's office. Stress-induced respiratory alkalosis was highly suspected as the cause for the alkaline urine. If traditional causes for alkaline urine are not apparent for cats that produce alkaline urine at the veterinary clinic, we suggest that urinary pH be determined on samples collected in the home.

Alkalosis, Respiratory↗
PubMed1996

Urethroscopy, cystoscopy, and biopsy of the feline lower urinary tract.

This article discusses the utility and limitations of urethroscopy and cystoscopy in both male and female cats. The special equipment and techniques necessary to adequately visualize the urethra and bladder of female cats are described in some detail. The emerging ability to visualize the male urethra is introduced. Photographs taken through the cystoscope are used to illustrate both normal anatomy and lesions likely to be encountered with cats with lower urinary tract disease. Cystoscopy is an important diagnostic tool for an inclusionary and exclusionary diagnosis of interstitial cystitis (sterile idiopathic inflammation).

Anesthesia↗
PubMed1996

Benefits of calcitriol therapy and serum phosphorus control in dogs and cats with chronic renal failure. Both are essential to prevent of suppress toxic hyperparathyroidism.

Daily oral calcitriol at low doses is safe and effective in the control of renal secondary hyperparathyroidism in dogs and cats. Low doses of calcitriol are most effective when started early in uremia before the advanced stages of renal secondary hyperparathyroidism. At early stages calcitriol both diminishes PTH synthesis in the parathyroid cells present and prevents the hyperplasia that, if unchecked, results in the most extensive an difficult-to-control hyperparathyroidism. The salutary effects on the dog's or cat's sense of well being, appetite, activity, strength, and lifespan as reported by the veterinarians of our survey are attributed primarily to keeping PTH levels below a toxic threshold. Additionally, some of the benefits achieved by calcitriol are likely a direct consequence of calcitriol interacting with the vitamin D receptor in a wide variety of tissues throughout the body. Phosphorus restriction through a combination of diet and intestinal phosphate binders is important to allow calcitriol therapy to successfully lower PTH levels, but it likely has no direct effects that are independent of interactions involving calcitriol. Phosphorus restriction is also important to minimize chances for adverse tissue mineralization. Calcitriol therapy can be considered for treatment of chronic renal failure after serum phosphorus has been decreased to less than 6.0 mg/dL in patients in whom it was initially elevated. Calcitriol supplementation to dogs and cats with chronic renal failure makes good endocrinologic sense. Calcitriol deficits cause increased PTH and, as these two hormones are designed to maintain calcium and phosphorus homeostasis, the PTH increase is initially adaptive. One of the important effects of PTH is to stimulate additional calcitriol formation as a powerful means to raise blood calcium through increased calcium absorption from the diet. With too great an increase in PTH, however, its effects become harmful to many tissues due to the widespread distribution of the PTH receptor in many cell types that are likely normally responsive only to the paracrine PTH-related peptide that shares the PTH receptor. Exogenous supplemental calcitriol administration allows concentrations of calcitriol in the bloodstream to remain normal without the toxic consequences of excessive PTH secretion that would otherwise be provoked. Studies involving young dogs with subtotal nephrectomy may not parallel those on older dogs and cats with spontaneous chronic renal failure. In particular, higher doses are needed to effect PTH change in these young dogs than we have found necessary for older dogs and cats. Because survey participants agreed most strongly with the idea that their calcitriol-treated dogs and cats were living longer than comparably uremic animals they had treated previously, further studies to evaluate the ability of calcitriol to retard the progression of renal lesions and loss of excretory renal function seem warranted. Additional studies to document the beneficial effects of calcitriol on the many organs adversely affected by excess PTH during uremia are also needed because findings thoroughly documented and proven in humans and rats may not always extrapolate to dogs and cats.

Animals↗
PubMed1996

Interstitial cystitis in cats.

Despite much research on FUS, there still is no consensus regarding its cause, or even its definition. We recently have demonstrated that some cases of FUS are similar to interstitial cystitis in human beings. Exclusion of anatomic defects, behavior abnormalities, neoplasia, urolithiasis, urethral obstruction, and urinary tract infection leads one to the diagnosis of interstitial cystitis in cats. This diagnosis suggests the need for new approaches to treatment, including pain management and environmental modification.

Animals↗
PubMed1996

A study of maxillofacial injuries in the elderly resulting from falls.

Falls are a major problem for the elderly, both in terms of the injuries sustained and the consequent loss of confidence and independence. Many studies, both prospective and retrospective, have investigated the possible causes and the resulting injuries following falls. However, no specific consideration appears to have been given to maxillofacial injuries. This survey examines the incidence of such injuries, over a three year period, in elderly patients presenting at an Accident and Emergency Department, and reviews the causes. Recognition of old age abuse is an essential aspect of the assessment of injuries in this group of patients.

Accidental Falls↗
PubMed1996

Fractionation of canine serum calcium, using a micropartition system.

OBJECTIVE: To determine usefulness of a micropartition system for calcium fractionation of canine serum, and to establish reference values for protein-bound, complexed, and ionized calcium fractions in clinically normal dogs. DESIGN: Performance characteristics of a micropartition system were evaluated, using serum from clinically normal dogs. This micropartition system was then used to determine a reference range for calcium fractions. ANIMALS: 13 clinically normal dogs. PROCEDURE: Dog serum was placed in the micropartition system, and spun for 20 minutes at 1,300 x g. Total calcium concentration, ionized calcium concentration, and pH were measured in whole serum, and total calcium concentration was measured in the ultrafiltrate. The protein-bound fraction was calculated by subtracting total calcium of the ultrafiltrate from total calcium of whole serum. The ionized calcium measurement of whole serum was subtracted from the total calcium measurement of the ultrafiltrate, determining the complexed calcium fraction. RESULTS: During validation of the ability of the micropartition system to separate calcium fractions, no significant amount of serum calcium was adsorbed by the plastic micropartition system or membrane. The micropartition membrane separated the protein-bound calcium fraction (retentate) from the ultrafiltrate, which contained ionized and complexed fractions of calcium. Concentrations of protein-bound, ionized, and complexed calcium from clinically normal dogs were determined to be 3.40 +/- 0.63, 5.49 +/- 0.17, and 1.01 +/- 0.30 mg/dl, representing 34, 56, and 10% of the total calcium concentration, respectively. CONCLUSIONS: This method is a rapid, repeatable means to completely fractionate serum calcium, and most importantly provides accurate assessment of the protein-bound and complexed calcium fractions. CLINICAL RELEVANCE: Complete assessment of calcium fractions may increase sensitivity for detection of disease processes that affect calcium metabolism.

Analysis of Variance↗
PubMed1995

Effects of storage on serum ionized calcium and pH values in clinically normal dogs.

The stability of ionized calcium (CaI) concentration and pH in sera (n = 14) stored at 23 or 4 C for 6, 9, 12, 24, 48, or 72 hours, or -10 C for 1, 3, 7, 14, or 30 days was evaluated. Also studied were the effects of oxygen exposure, cold handling, and feeding on CaI and pH values. Results indicated that serum CaI concentration was stable throughout 72 hours of storage at 23 or 4 C, and for 7 days at -10 C. Serum CaI concentration significantly (P < 0.05) decreased by 14 days of storage at -10 C. Serum pH was stable for 6 hours at 23 or 4 C, and for 24 hours at -10 C, but significantly (P < 0.05) increased by 9 hours of storage at 23 or 4 C and by 3 days at -10 C. Exposure of the surface of the serum to air immediately before measurement had no effect on CaI or pH values, but mixing serum with air resulted in significantly (P < 0.05) decreased CaI concentration and increased pH. Handling of blood on ice resulted in significantly (P < 0.05) higher serum pH, compared with blood handled at 23 C, but serum CaI concentration was unaffected. Serum obtained at 2 hours after feeding did not have any significant changes in CaI, total calcium, or pH values. It appears that if canine serum is obtained, handled, and stored anaerobically, CaI concentration can be accurately measured after 72 hours at 23 or 4 C, or after 7 days at -10 C.

Animals↗
PubMed1993

Development of chronic renal disease in cats fed a commercial diet.

Chronic renal failure was observed in 10 young adult client-owned cats that had been fed 1 commercial cat food exclusively since weaning. The diet contained 40% protein and 0.32% potassium on a dry matter basis, and phosphoric acid was added during production. We attempted to determine whether exclusive feeding of this diet would induce clinical and laboratory evidence of renal dysfunction in clinically normal adult cats. Over a 2-year study, 3 of 9 of these cats developed clinical and laboratory evidence of renal dysfunction and renal lesions. Two additional cats developed renal lesions, but had normal laboratory values. The renal lesions consisted of lymphoplasmacytic interstitial nephritis and interstitial fibrosis. We concluded that chronic renal disease may develop in clinically normal adult cats fed diets high in protein and acid content, but marginally replete in potassium.

Animal Feed↗
PubMed1993

Reproducibility of urethral pressure profiles in clinically normal sexually intact female dogs by use of microtransducer catheters.

Urethral pressures profiles (UPP) obtained by use of microtransducer catheters were determined in 8 anestrous sexually intact female Beagles during general anesthesia. A UPP study consisted of 3 consecutive recordings, and 4 UPP studies were repeated at an interval of 5 days in each dog. Maximal urethral pressure (cm of H2O), bladder pressure (cm of H2O), and anatomic urethral length (cm) were recorded. Maximal urethral closure pressure (cm of H2O) was calculated. Mean +/- SD (for all measurements) maximal urethral closure pressure was 12.8 +/- 5.6 cm of H2O (range, 2.4 to 25.2 cm of H2O). Maximal urethral closure pressure was significantly (P < 0.05) decreased during the first recording period (11.4 +/- 5.8 cm of H2O), compared with the second (13.0 +/- 5.2 cm of H2O) or third (14.1 +/- 5.7 cm of H2O) recording periods within a UPP study (3 consecutive recordings). Mean maximal difference in urethral closure pressure during a single UPP study was 4.8 +/- 2.4 cm of H2O. Significant difference in maximal urethral closure pressure was not observed between studies. Mean (for all measurements) anatomic urethral length was 6.2 +/- 0.9 cm (4.1 to 7.8 cm). Anatomic urethral length was significantly (P < 0.05) less during the first recording period (6.1 +/- 0.9 cm), compared with values for the second and third periods (6.3 +/- 0.9 cm, 6.4 +/- 0.9 cm respectively). Anatomic urethral length for time 3 was significantly (P < 0.05) less than the value for time 1 (5.8 +/- 0.7 cm vs 6.6 +/- 0.8 cm).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Effects of mithramycin on calcium metabolism and bone in dogs.

Mithramycin (0.1 mg/kg) was administered intravenously to eight Beagle dogs on days 0 and 7 to determine its effects on calcium and phosphorus metabolism, serum parathyroid hormone concentration, osteoclastic bone resorption, and serum biochemical and hematologic parameters. Ionized calcium concentration was paradoxically increased on day 1 and decreased on day 8 in association with an increased serum parathyroid hormone concentration. Serum phosphorus concentration was decreased on days 1 and 2. Osteoclastic bone resorption in iliac cancellous bone was significantly decreased on day 8. There were mild increases in serum alkaline phosphatase (days 1, 2, 4, 8, 9), aspartate aminotransferase (day 9), and gammaglutamyl transpeptidase (days 7, 9) activities. Platelet numbers were increased on days 7 through 13, and packed red blood cell volumes were mildly decreased. This investigation demonstrates that two doses of mithramycin can be administered safely to dogs and may inhibit bone resorption in diseases associated with increased osteoclastic bone resorption, such as humoral hypercalcemia of malignancy.

Animals↗
PubMed1992

Parathyroid hormone (PTH)-related protein, PTH, and 1,25-dihydroxyvitamin D in dogs with cancer-associated hypercalcemia.

Circulating N-terminal PTH-related protein (PTHrP), N-terminal PTH, and 1,25-dihydroxyvitamin D [1,25-(OH)2D] concentrations were measured in normal dogs and dogs with cancer-associated hypercalcemia (CAH), parathyroid adenomas, and miscellaneous tumors. PTHrP was undetectable (less than 1.8 pM) in normal dogs and increased in dogs with CAH due to adenocarcinomas derived from apocrine glands of the anal sac (44.9 +/- 27 pM), lymphoma (8.3 +/- 4.4 pM), and miscellaneous carcinomas (13.3 +/- 11.4 pM). The PTHrP concentration decreased in dogs with lymphoma and anal sac adenocarcinomas after successful treatment of CAH. The PTHrP concentration had a significant linear correlation with total serum calcium in dogs with anal sac adenocarcinomas and hypercalcemia, but not in dogs with lymphoma and hypercalcemia. Serum N-terminal PTH concentrations were usually in the normal range (12-34 pg/ml) for all groups of dogs except dogs with parathyroid adenomas (83 +/- 38 pg/ml). The serum PTH concentration increased after successful treatment of CAH. Serum 1,25-(OH)2D concentrations were decreased, normal, or increased in dogs with CAH, and 1,25-(OH)2D levels decreased after treatment of CAH. In summary, circulating concentrations of PTHrP are consistently increased in dogs with CAH, and PTHrP appears to play an important role in the induction of hypercalcemia.

Adenoma↗
PubMed1992

Nephrocalcinosis caused by hyperparathyroidism in progression of renal failure: treatment with calcitriol.

Nephrocalcinosis is accepted to contribute to the progression of renal failure. We have reviewed evidence that nephrocalcinosis is caused directly by the excess parathyroid hormone produced in renal disease. Evidence that hyperparathyroidism in uremic patients results from calcitriol deficiency and the mechanisms by which this comes about have been discussed. We have shown that renal secondary hyperparathyroidism can be eliminated or substantially reduced without increasing blood calcium using a low-dosage regimen of calcitriol. Decreasing PTH concentrations to or near normal alleviates this hormone's toxicity to many organs, including the kidneys. Potential benefits for the uremic patient include an increase in the quality and length of life. Calcitriol treatment provides a powerful means to reduce PTH concentration in uremic patients that may not be achieved with other methods. Further prospective clinical studies of uremic dogs and cats are warranted to document preservation of renal function and histology during calcitriol treatments.

Animals↗
PubMed1992

Clinical and metabolic findings in dogs with chronic renal failure fed two diets.

Exogenous creatinine clearance, urinary electrolyte excretions, calcium and phosphorus balance, serum cholesterol concentration, arterial blood pressure, and body weight were evaluated in dogs with chronic renal failure that were fed 2 commercial diets. Nine dogs ranging in age from 1 to 15 years were identified as having mild to moderate chronic renal failure (CRF, exogenous creatinine clearance = 0.5 to 2.13 ml/kg of body weight/min). These dogs and a group of 10 clinically normal controls were fed a diet containing 31% protein for 8 weeks at which time hematologic and biochemical evaluations and clearance studies were performed. All dogs then were fed a phosphorus-restricted diet containing 16% protein and then reevaluated after 8 weeks. The dogs in this study had hematologic and biochemical abnormalities typical of CRF. Urine absolute and fractional excretion of electrolytes was higher in dogs with CRF than in controls and was affected by diet. Serum cholesterol concentration was higher in dogs with CRF and increased in those dogs after feeding the low protein diet. Changes in dietary sodium intake did not affect arterial blood pressure. The phosphorus-restricted diet did not affect serum amino terminal parathyroid hormone concentration in either group. Control dogs lost body weight, whereas dogs with CRF gained weight when fed the low protein diet. We concluded that dogs with mild to moderately severe CRF have the same biochemical abnormalities and response to dietary restriction of protein and phosphorus as has been previously reported in dogs with experimentally induced CRF. Restriction of dietary sodium may not decrease arterial blood pressure in some dogs with CRF.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗
PubMed1992

Amino acid profiles in dogs with chronic renal failure fed two diets.

Amino acid profiles and serum albumin and serum total protein concentrations were evaluated in dogs with renal disease. Nine dogs ranging in age from 1 to 15 years were identified as having mild to moderate chronic renal failure (CRF; exogenous creatinine clearance, 0.5 to 2.13 ml/kg of body weight/min). These dogs and a group of 10 clinically normal control dogs were fed a diet containing 31% protein for 8 weeks, at which time serum and urine amino acid assays and clearance studies were performed. All dogs then were fed a diet containing 16% protein for 8 weeks and then reevaluated. Chronic renal failure was associated with mild abnormalities in serum concentrations of amino acids. When fed the higher protein diet, dogs with CRF had lower serum concentrations of glutamine, leucine, proline, and serine and higher serum concentrations of cystathionine and 3-methylhistidine than clinically normal control dogs. When fed the low protein diet, dogs with CRF had lower serum serine concentrations and higher serum concentrations of cystathionine, phenylalanine, and 3-methylhistidine. Urine excretion of amino acids in all dogs on both diets was low, and dogs with CRF had lower renal clearances of 3-methylhistidine than control dogs. There were no significant differences in concentrations of serum albumin and total solids between either group, regardless of diet. We concluded that dogs with mild to moderately severe CRF have mild abnormalities of serum free amino acid concentrations, but renal conservation of essential amino acids is not impaired.

Amino Acids↗