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Biomedical subjects

C A Brown

Publications and source records attributed to C A Brown.

At least 73 records · Page 4Linked to original sources
PubMed1998

Interventional nutrition for renal disease.

Interventional nutrition plays a central role in the management of renal diseases in veterinary medicine. Most of the clinically observable abnormalities produced by the disruption of renal function are influenced by dietary intake of calories, phosphorus, sodium, potassium, protein, or acid load. Further, the kidney is susceptible to self-perpetuating injury, an inherent property of this organ, and the extent of this injury can be modified by adjustments in dietary intake of phosphorus and polyunsaturated fatty acids. The response of each animal with renal insufficiency to the disease and to nutritional intervention varies dramatically, and individualized therapy is required; the only constant nutritional characteristic of renal insufficiency is inappetance and loss of body weight. Successful interventional nutrition must take all of these principles into account.

Acid-Base Equilibrium↗
PubMed1998

Is there a role for dietary polyunsaturated fatty acid supplementation in canine renal disease?

Dogs with spontaneous renal diseases frequently develop progressive uremia. After partial nephrectomy, a similar pattern of progressively declining renal function develops. This pattern may be attributed in part to the development of glomerular hypertension in remnant canine nephrons. Changes in the composition of dietary polyunsaturated fatty acids (PUFA) modify glomerular hemodynamics in normal rats and affect the chronic course of renal disease in partially nephrectomized rats. Thus, dietary PUFA supplementation might alter progressive canine nephropathies. However, the response of dogs with renal insufficiency to dietary manipulations frequently differs substantially from that of laboratory rodents, and the effects of dietary PUFA composition have been poorly characterized in dogs with chronic renal disease. Here we address the hypothesis that dietary PUFA supplementation may delay the progression of chronic renal insufficiency in dogs. In particular, dogs ingesting diets supplemented with (n-6) PUFA exhibited severe glomerular hypertension associated with rapidly progressive renal failure. In contrast, dietary supplementation with (n-3) PUFA prevented deterioration of the glomerular filtration rate and preserved renal structure. The results of these model studies demonstrate that dietary PUFA supplementation may alter renal hemodynamics and the long-term course of renal injury in dogs. Clinical trials to address the potential benefits of dietary (n-3) PUFA supplementation in a variety of spontaneous renal diseases seem warranted.

Animals↗
PubMed1998

Reduction of carriage of enterohemorrhagic Escherichia coli O157:H7 in cattle by inoculation with probiotic bacteria.

Bacteria inhibitory to Escherichia coli O157:H7 were isolated from cattle and evaluated for their potential for reducing carriage of E. coli O157:H7 in calves. Eighteen of 1,200 bacterial isolates from cattle feces and intestinal tissue samples were screened and determined to inhibit the growth of E. coli O157:H7 in vitro. Seventeen of the isolates were E. coli and one was Proteus mirabilis. None produced Shiga toxin. Genomic DNA fingerprinting by pulsed-field gel electrophoresis revealed 13 distinguishable profiles among the 18 isolates. Two calves inoculated perorally with a mixture of all 18 isolates (10(10) CFU) appeared to be normal and did not develop signs of clinical disease throughout a 25- to 27-day observation period. These bacteria colonized segments of the gastrointestinal tract and were in feces at the termination of the experiment (25 and 27 days postinoculation) at levels of 50 to 200 CFU/g. Fifteen cannulated calves were studied to determine the efficiency of the probiotic bacteria in reducing or eliminating the carriage of E. coli O157:H7. Nine calves served as controls, with each animal receiving perorally 10(10) CFU of E. coli O157:H7. E. coli O157:H7 was detected intermittently in the rumen samples from all control animals throughout 3 weeks postinoculation, whereas E. coli O157:H7 was shed at various levels in feces continuously throughout the experiment (mean, 28 days). E. coli O157:H7 was isolated from the rumens and colons of eight of nine and nine of nine calves, respectively, at the termination of the study. Six calves each received perorally 10(10) CFU of probiotic bacteria and then 2 days later received 10(10) CFU of E. coli O157:H7. E. coli O157:H7 was detected in the rumen for only 9 days postinoculation in two animals, for 16 days in one animal, for 17 days in two animals, and for 29 days in one animal. E. coli O157:H7 was detected in feces for only 11 days postinoculation in one animal, for 15 days in one animal, for 17 days in one animal, for 18 days in one animal, for 19 days in one animal, and for 29 days in one animal. At the end of the experiment (mean, 30 days), E. coli O157:H7 was not recovered from the rumen of any of the six animals treated with probiotic bacteria; however, E. coli O157:H7 was recovered from the feces of one of the animals. This animal was fasted twice postinoculation. These studies indicate that selected probiotic bacteria administered to cattle prior to exposure to E. coli O157:H7 can reduce the level of carriage of E. coli O157:H7 in most animals.

Animals↗
PubMed1998

Evaluation of the microbiology of chronic maxillary sinusitis.

Chronic paranasal sinusitis is a disease that afflicts a significant percentage of the population and causes considerable long-term morbidity. With the common use of multiple courses of broad-spectrum oral antibiotics to treat this condition, there is a possibility of an alteration in the pathogens that promote a persistence of chronic sinusitis. One hundred seventy-four consecutive patients with a diagnosis of chronic maxillary sinusitis requiring an endoscopic surgical procedure were prospectively evaluated. At the time of surgery, cultures of mucopus in the maxillary sinus were aseptically obtained endoscopically and cultured for aerobes, anaerobes, and fungus. Two hundred seventeen isolates from 174 patients were obtained. Coagulase-negative staphylococci were the most common isolates (36%), followed by Staphylococcus aureus (25%), Streptococcus viridans (8.3%), Corynebacterium (4.6%), and anaerobes (6.4%). Although coagulase-negative Staphylococcus is not considered a pathogen, of the 24 isolates that had sensitivity testing performed, 13 demonstrated resistance to multiple antibiotics, including cephalothin, erythromycin, oxacillin, sulfonamides, and clindamycin. This study demonstrates that aerobic rather than anaerobic bacteria are the more common pathogens in chronic sinusitis. In addition, coagulase-negative Staphylococcus may be a pathogen in the disease process, and sensitivities should be obtained of this isolate for evaluation and possible treatment.

Adult↗
PubMed1998

Two-phase study of hepatic artery vascular occlusion with microencapsulated cisplatin in patients with liver metastases from neuroendocrine tumors.

OBJECTIVE: We conducted a two-phase trial in which 100-micron polylactic acid microcapsules with a cisplatin payload (manufactured at our institution [the M. D. Anderson Cancer Center]) were used for hepatic artery occlusion therapy for symptomatic patients who had liver metastases from neuroendocrine tumors. SUBJECTS AND METHODS: Between January 1993 and December 1995, 20 patients with advanced, unresectable, symptomatic neuroendocrine tumors with liver metastases received repeated hepatic artery occlusion therapy using encapsulated cisplatin. The dose of encapsulated cisplatin was increased in a stepwise fashion. Selective angiography was used to occlude the portion of the hepatic vasculature that had the most metastases with encapsulated cisplatin microcapsules. In each patient, hepatic artery occlusion therapy was repeated in 6-8 weeks and responses were evaluated. Subsequent vascular occlusions were performed on the basis of the level of palliation achieved and the persistence of symptoms. RESULTS: Of the 20 patients, 17 patients had carcinoid tumors and three had islet cell tumors. The median percentage of liver replacement was approximately 50%. Fifteen of the 20 patients had received prior therapy and 17 patients had hormonal syndrome at the beginning of therapy. One patient had tumor bulk-related symptoms. Nineteen patients had elevated peptides markers that could be followed serially Six patients received encapsulated cisplatin at 50 mg/m2, four patients at 75 mg/m2, and 10 patients at 100 mg/m2 of body surface area. The median number of vascular occlusive procedures per patient was three. All patients were assessable for toxicity and 18 were assessable for response (the other two patients were not assessable because of loss of follow-up). The median follow-up time was 14 months. Twelve (67%) of 18 patients had a median reduction in symptoms of 50%. Eleven (73%) of 15 patients with elevated 24-hr-urine levels of 5-hydroxyindoleacetic acid had a median reduction of 64% for this symptom. We observed objective reduction in the tumors of 14 of the 18 patients. In six of the 14 patients, we noted a partial response. In eight, we observed a minor response. In four of the 18 patients, we noted no response. One treatment-related death resulted from hepatorenal syndrome. Other major complications included hepatic pain (100%), fever (100%), nausea (100%), and vomiting (95%). Also all patients had a transient elevation of liver enzymes. Five of the 20 patients died of disease during our study. CONCLUSION: Hepatic artery vascular occlusion therapy using encapsulated cisplatin is feasible, can palliate symptoms, and can produce biochemical and objective responses in liver metastases from neuroendocrine tumors. The maximum tolerated dose appears to be 100 mg/m2 of body surface area per treatment. Polylactic acid capsules have potential because they can incorporate multiple agents. With surface coating, such capsules can also be used to target specific receptors.

Adenoma, Islet Cell↗
PubMed1998

Increasing consumer satisfaction. One social service and public health initiative shows how social marketing can increase consumer satisfaction.

The key to a successful social marketing approach to health care is continually listening to consumers' feedback and being willing to change the health product or service according to their needs and preferences. This approach can increase the likelihood of consumers being satisfied with, and continuing to utilize or provide the particular health service.

Consumer Behavior↗
PubMed1998

Protein and calorie effects on progression of induced chronic renal failure in cats.

OBJECTIVE: To determine effects of dietary protein and calories on progression of induced chronic renal failure in cats. ANIMALS: 28 young adult female cats. PROCEDURE: Renal mass was reduced surgically, and glomerular filtration rate (GFR) was determined. Cats were alloted to 4 groups of 7 with similar mean GFR (1.52 to 1.55 ml/min/kg of body weight). Diets were formulated to provide: low protein and calorie (diet A), low protein and high calorie (diet B), high protein and low calorie (diet C), and high protein and calorie (diet D) intakes. Cats were fed their prescribed diet for 12 months, then blood and urine biochemical variables were measured, after which kidney specimens were examined microscopically. RESULTS: Protein intake by cats of groups C and D (9.0 g/d/kg) was substantially greater than that by cats of groups A and B (5.3 and 5.2 g/d/kg, respectively). Caloric intake by cats of groups B and D (73 and 71 calories/d/kg, respectively) was greater than that by cats of groups A and C (58 and 55 calories/d/kg, respectively). Renal glomerular lesions were mild and not affected by protein, calories or their interactions. Nonglomerular lesions, though mild, were significantly influenced by calorie intake, but not by protein or calorie-protein interactions. The GFR did not decrease in any group. Urine protein-to-creatinine ratio increased significantly in all groups after reduction of renal mass, but values from all groups remained within the reference range (0 to 0.3). CONCLUSIONS AND CLINICAL RELEVANCE: Diets replete in protein were not associated with increased severity of glomerular or nonglomerular renal lesions, increased proteinuria, or decreased GFR. Diets replete in calories were not associated with increased severity of glomerular lesions, but were associated with mild increase of nonglomerular lesions. Factors other than protein and calorie intake must be considered potential causes of progression of renal failure in cats. Results raise questions about the practice of restricting quantity of protein in the diet of cats with chronic renal failure, with the intention of ameliorating development of further renal damage.

Adipose Tissue↗
PubMed1997

Overwhelming strongyloidosis in a foal.

A 6-month-old foal was evaluated because of weakness, weight loss, and inappetence of 3 weeks' duration. On initial examination, the foal was weak, poorly responsive, and emaciated. Clinicopathologic abnormalities included anemia and hypoproteinemia. Because of its severe debilitation, the foal was euthantized. Necropsy revealed marked infection of the small intestine with Strongyloides westeri and severe edema of the entire gastrointestinal tract. The foal had been orphaned when it was 6 hours old and raised in isolation from other horses. We believe that this foal developed overwhelming strongyloidosis when it was first exposed to other foals at 5 months of age, because it had not been naturally exposed to the organism at a younger age and was immunologically naive.

Animals↗
PubMed1997

An improved methodology for the detection of the common mutation in the FGFR3 gene responsible for achondroplasia.

Homozygous achondroplasia is a neonatal lethal condition which can only be diagnosed in the first trimester of pregnancy by molecular analysis. The vast majority of patients with achondroplasia have a G-->A substitution at position 1138 of the fibroblast growth factor receptor (FGFR3) cDNA sequence, resulting in the substitution of an arginine for a glycine residue at position 380 of the FGFR3 protein. This mutation has typically been detected by SfcI digestion of amplified genomic DNA. We have demonstrated that the SfcI digestion protocol does not consistently distinguish between DNA samples heterozygous and homozygous for the G1138A substitution, and illustrates how the misdiagnosis of a homozygous affected fetus for one carrying only one copy of the G1138A mutation could occur. We report here an improved, simple nonradioactive technique which can reliably and consistently detect the presence of the G1138A mutation both in the heterozygous and homozygous state.

Achondroplasia↗
PubMed1997

Pathophysiology and management of progressive renal disease.

Recently, the hypothesis that all renal diseases are inherently progressive and self-perpetuating has focused attention on adaptive changes in renal structure and function that occur whenever renal function is reduced. These glomerular adaptations to renal disease include increases in filtration rate, capillary pressure and size, and are referred to as glomerular hyperfiltration, glomerular hypertension and glomerular hypertrophy, respectively. Extrarenal changes, such as dietary phosphate excess, systemic hypertension, hyperlipidaemia, acidosis and hyperparathyroidism occur in animals with renal disease and may be contributors to progression of renal disease. Emphasis in the management of companion animals with renal disease has shifted to identifying, understanding and controlling those processes that play a role in the progression from early to end-stage renal failure. Advances made by veterinary nephrologists in the past 15 years permit resolution of old controversies, formulation of new hypotheses and discussion of unresolved issues about the nature of progressive renal disease in dogs and cats.

Animals↗
PubMed1997

Enhancement of the response to purinergic agonists in P2Y1 transfected 1321N1 cells by antagonists suramin and PPADS.

1. We have previously shown that both suramin and pyridoxal-phosphate-6-azophenyl-2',4' disulphonic acid (PPADS) act as antagonists at transfected P2Y1 receptors. Here we show that under certain experimental conditions these two P2 antagonists can enhance the response to agonists acting at these receptors. 2. The expression of either P2Y1 or P2Y2 receptors in 1321N1 human astrocytoma cells results, on a change of medium, in an elevation of basal (no added agonist) accumulation of [3H]-inositol(poly)phosphates([3H]-InsPx) compared to cells not expressing these receptors. This elevation is much greater in P2Y1 transfectants than in P2Y, transfectants. 3. Both PPADS and suramin reduced this basal level of [3H]-InsPx accumulation in the P2Y1 expressing cells. 4. When a protocol was used which required changing the culture medium, antagonists were added at a concentration which reduced the basal accumulation by about 50%, there was a significant stimulation in response to increasing concentrations of 2-methylthioadenosine 5'-triphosphate (2MeSATP), in the absence of antagonists there was no significant effect of the agonist. 5. However, when 2MeSATP was added in the absence of a change of medium and with no antagonist present, there was a several fold increase in [3H]-InsPx accumulation. These results show that a release of endogenous agonist activity (possibly ATP/ADP) from the P2Y1 expressing cells can create conditions in which a response to an agonist such as 2MeSATP can only be seen in the presence of a competitive antagonist.

Adenosine Triphosphate↗
PubMed1997

Interactions between imidazoline compounds and sulphonylureas in the regulation of insulin secretion.

1. Imidazoline alpha 2-antagonist drugs such as efaroxan have been shown to increase the insulin secretory response to sulphonylureas from rat pancreatic B-cells. We have investigated whether this reflects binding to an islet imidazoline receptor or whether alpha 2-adrenoceptor antagonism is involved. 2. Administration of (+/-)-efaroxan or glibenclamide to Wistar rats was associated with a transient increase in plasma insulin. When both drugs were administered together, the resultant increase in insulin levels was much greater than that obtained with either drug alone. 3. Use of the resolved enantiomers of efaroxan revealed that the ability of the compound to enhance the insulin secretory response to glibenclamide resided only in the alpha 2-selective-(+)-enantiomer; the imidazoline receptor-selective-(-)-enantiomer was ineffective. 4. In vitro, (+)-efaroxan increased the insulin secretory response to glibenclamide in rat freshly isolated and cultured islets of Langerhans, whereas (-)-efaroxan was inactive. By contrast, (+)-efaroxan did not potentiate glucose-induced insulin secretion but (-)-efaroxan induced a marked increase in insulin secretion from islets incubated in the presence of 6 mM glucose. 5. Incubation of rat islets under conditions designed to minimize the extent of alpha 2-adrenoceptor signalling (by receptor blockade with phenoxybenzamine; receptor down-regulation or treatment with pertussis toxin) abolished the capacity of (+)- and (+/-)-efaroxan to enhance the insulin secretory response to glibenclamide. However, these manoeuvres did not alter the ability of (+/-)-efaroxan to potentiate glucose-induced insulin secretion. 6. The results indicate that the enantiomers of efaroxan exert differential effects on insulin secretion which may result from binding to effector sites having opposite stereoselectivity. Binding of (-)-efaroxan (presumably to imidazoline receptors) results in potentiation of glucose-induced insulin secretion, whereas interaction of (+)-efaroxan with a second site leads to selective enhancement of sulphonylurea-induced insulin release.

Adrenergic alpha-Antagonists↗
PubMed1997

Experimental Escherichia coli O157:H7 carriage in calves.

Nine weaned calves (6 to 8 weeks of age) were given 10(10) CFU of a five-strain mixture of enterohemorrhagic Escherichia coli O157:H7 by oral-gastric intubation. After an initial brief period of pyrexia in three calves and transient mild diarrhea in five calves, calves were clinically normal throughout the 13- to 27-day study. The population of E. coli O157:H7 in the faces decreased dramatically in all calves during the first 2 weeks after inoculation. Thereafter, small populations of E. coli O157:H7 persisted in all calves, where they were detected intermittently in the feces and rumen contents. While withholding food increased fecal shedding of E. coli O157:H7 by 1 to 2 log10/g in three of four calves previously shedding small populations of E. coli O157:H7, the effect of fasting on fecal shedding of E. coli O157:H7 was variable in calves shedding larger populations. At necropsy, E. coli O157:H7 was not isolated from sites outside the alimentary tract. E. coli O157:H7 was isolated from the forestomach or colon of all calves at necropsy. Greater numbers of E. coli O157:H7 were present in the gastrointestinal contents than in the corresponding mucosal sections, and there was no histologic or immunohistochemical evidence of E. coli O157:H7 adhering to the mucosa. In conclusion, under these experimental conditions, E. coli O157:H7 is not pathogenic in weaned calves, and while it does not appear to colonize mucosal surfaces for extended periods, E. coli O157:H7 persists in the contents of the rumen and colon as a source for fecal shedding.

Animals↗