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Biomedical subjects

M A Davis

Publications and source records attributed to M A Davis.

At least 163 records · Page 9Linked to original sources
PubMed1988

Strains of Escherichia coli associated with urogenital disease in dogs and cats.

Selected strains of Escherichia coli associated with urogenital disease in dogs and cats were evaluated for 3 virulence factors associated with human uropathogenic strains. Urogenital strains of E coli from dogs and cats had high prevalence of alpha hemolysin and were clustered in 5 to 10 somatic serogroups, attributes also shared by human uropathogenic strains. However, the canine and feline urogenital strains failed to have increased prevalence of mannose-resistant hemagglutination, as has been reported for human uropathogenic strains.

Animals↗
PubMed1988

Selective embolization and clot dissolution with tPA in the internal carotid artery circulation of the rabbit.

We describe a model of thromboembolic stroke in rabbits that utilizes the Seldinger technique and digital arteriography. The internal carotid arteries of 14 rabbits were catheterized selectively and embolized with autologous blood clots. After embolization, eight rabbits received IV tissue plasminogen activator (tPA); the remaining six were infused with saline and served as controls. After embolization, cerebral arteriograms were obtained at 30-min intervals for 180 min. Cerebral arteriograms obtained after tPA therapy revealed partial or complete thrombus dissolution in seven (88%) of the eight treated rabbits. In the control group, none of the arteriograms of the embolized internal carotid arteries showed thrombus dissolution. In the tPA-treated group, the median time for thrombus dissolution was 60 min. This stroke model is economical, reproducible, and less traumatic to the brain than most of the previously described animal models. It also provides a means to compare the safety and efficacy of various thrombolytic agents in small animals.

Animals↗
PubMed1988

The role of metabolic factors and blood pressure in the association of obesity with osteoarthritis of the knee.

The role of systemic/metabolic factors in the association of obesity with knee osteoarthritis (OA) was analyzed using radiographic data, metabolic measures, and blood pressure for 3885 American adults aged 45-74 from the U.S. National Health and Nutrition Examination Survey, 1971-1975 (NHANES I). Obesity was associated with both bilateral and unilateral OA, but more strongly with bilateral OA. Controlling for age, sex, serum cholesterol, serum uric acid, diabetes, body fat distribution, and blood pressure did not significantly reduce the association between obesity and knee OA. Findings from these data are not supportive of a metabolic link between obesity and knee OA.

Adipose Tissue↗
PubMed1988

Epidemiology of osteoarthritis.

Although OA is recognized as the most common joint disorder, its pathogenesis is unclear and little is known about its natural history and progression. Epidemiologic studies have identified age as the strongest and most consistent correlate of OA, with distinct patterns of distribution by sex, ethnicity, and geographic location. There is growing consensus that OA represents a heterogeneous set of diseases that are affected by the interaction of multiple risk factors, producing a common pathway of disease; and that it is important to study multiple risk factors in association with generalized OA and site-specific subsets of OA. Two basic types of generalized OA are recognized, although it is quite possible that there are additional types of generalized OA. Genetic susceptibility, which implies some systemic factor of cartilage vulnerability, is thought to be the major risk factor for generalized OA. Mechanical factors associated with wear and tear on the joint have been the most important factors found in association with site-specific OA, although it is possible that systemic factors are also involved. Most likely there are multiple factors, such as genetic susceptibility; anatomic, biomechanical, and biochemical changes associated with aging; and exposure to various types of joint trauma and injury that are implicated in the etiology of OA. There is little known about progression of OA and the extent of the outcomes involved with progression of OA. Crucial to future epidemiologic research is the identification of homogeneous subsets of OA that facilitate standardized case definition, and research designs that incorporate multiple joints in one study and investigate the independent and interactive effects of multiple hypothesized risk factors. Cohort studies and longitudinal follow-up of persons with OA are needed in order to have a better understanding of the natural history of OA and its related outcomes.

Adult↗
PubMed1987

Net hepatic lactate balance following mixed meal feeding in the four-day fasted conscious dog.

The present experiments were undertaken to determine whether four days of fasting and marked hepatic glycogen depletion would alter the effect of mixed meal feeding on net hepatic lactate balance in the conscious dog. Dogs were fasted for four days and were then fed a mixed meal over a ten-minute period. Net hepatic glucose and lactate balance were monitored for the next eight hours using the A-V difference technique. The arterial plasma glucose level rose to a maximum of 121 +/- 3 mg/dL three hours after feeding and then decreased. Net hepatic glucose output declined to 0.44 +/- 0.44 mg/kg/min but the liver never became a net consumer of glucose. The arterial blood lactate level rose from 678 +/- 71 to 1000 +/- 158 mumol/L as the liver switched from net lactate uptake (12.2 +/- 2.0 mumol/kg/min) to net lactate production (4.3 +/- 1.7 mumol/kg/min). Over the course of the eight-hour postprandial period 25 g of glycogen were deposited in the liver. The net hepatic uptake of the gluconeogenic amino acids rose from 6.1 +/- 1.2 mumol/kg/min to a peak of 15.4 +/- 4.3 mumol/kg/min one hour after feeding. Net hepatic uptake of glycerol fell from 3.0 +/- 0.3 mumol/kg/min to an average of 1.5 +/- 0.4 mumol/kg/min. The plasma insulin level increased from 13 +/- 2 microU/mL at 3.5 hours and fell to 32 +/- 7 microU/mL by 8 hours. The plasma glucagon level rose from 22 +/- 3 pg/mL to 93 +/- 12 pg/mL 1.5 hours after feeding and fell to 68 +/- 6 pg/mL 8 hours after feeding.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMed1987

Complementation of areA- regulatory gene mutations of Aspergillus nidulans by the heterologous regulatory gene nit-2 of Neurospora crassa.

Loss-of-function mutations in the regulatory gene areA of Aspergillus nidulans prevent the utilization of a wide variety of nitrogen sources. The phenotypes of nit-2 mutants of Neurospora crassa suggest that this gene may be analogous to the areA gene. Transformation has been used to introduce a plasmid containing the nit-2 gene into A. nidulans. The nit-2 gene of Neurospora complemented mutations in the areA gene, restoring the ability to use a variety of nitrogen sources. This indicated that the activator function of nit-2 and areA gene products was retained across these two fungal species. Southern blot analysis revealed both single-copy and multicopy integrations and, in at least one case, integration appeared to generate a nit-2 mutation. Integration of the transforming plasmid appeared to be by nonhomologous events at a number of different sites in the Aspergillus genome. The transformants were less sensitive to nitrogen-metabolite repression of extracellular protease activity and nitrate reductase (EC 1.6.6.3) than were wild-type A. nidulans. This indicated that nitrogen control was not completely normal in the nit-2 transformants.

Aspergillus nidulans↗
PubMed1987

Nurses and social workers: rivals in the provision of social services?

As nurses strive to expand the areas in which they provide services, they may seek to perform tasks traditionally regarded by social workers as their own. This study asked hospice staff whether social workers or nurses were better qualified to perform social service tasks, and its findings suggest that role overlap may develop into a matter for social work concern.

Hospices↗
PubMed1987

Evaluation of Quantum II microbiology system for identification of gram-negative bacteria of veterinary origin.

The ability of a rapid, semiautomated bacterial identification system, the Quantum II microbiology system (Abbott Laboratories, Irving, Tex.), to accurately identify gram-negative bacteria from veterinary sources was evaluated. A total of 378 isolates were tested, including 298 organisms in the family Enterobacteriaceae and strains representing Acinetobacter sp., Aeromonas sp., Flavobacterium sp., Pasteurella multocida, Plesiomonas sp., and Pseudomonas spp. Of these isolates, 333 (88.1%) were correctly identified, 20 (5.3%) were not identified, 10 (2.6%) were incorrectly identified at the genus level, and 15 (4.0%) were incorrectly identified at the species level. The Quantum II system correctly identified 268 (89.9%) of the isolates of Enterobacteriaceae and 65 (81.3%) of the nonenteric isolates. P. multocida was not identified correctly, and some nonenteric gram-negative bacteria of clinical significance in veterinary medicine are not included in the data base. The Quantum II system provided an accurate identification system for isolates of Enterobacteriaceae but had limited usefulness for the identification of other gram-negative bacteria of clinical significance in veterinary medicine.

Animals↗
PubMed1987

Fat-density oral contrast agent for abdominal CT.

To overcome the problem of inadequate mixing of gastrointestinal (GI) tract contents with conventional high-density oral contrast agents in abdominal computed tomography (CT), a flavored 12.5% corn oil emulsion (COE) was tested as an oral contrast agent in 62 patients. The results were compared with those obtained from 105 patients who received high-density oral contrast agents. A simple patient preparation regimen for the COE was developed, which appears to be reasonably well tolerated by the patients and yields diagnostic studies comparable to those obtained with conventional agents. Use of the COE resulted in consistent discrimination of the GI tract and depiction of the GI wall. Preliminary data suggest that it may be particularly useful for CT evaluation of the stomach, duodenum, and pancreas; in patients suspected of having solid tumors; and in thin people.

Barium Sulfate↗
PubMed1987

Similar dose responsiveness of hepatic glycogenolysis and gluconeogenesis to glucagon in vivo.

This study was undertaken to determine whether the dose-dependent effect of glucagon on gluconeogenesis parallels its effect on hepatic glycogenolysis in conscious overnight-fasted dogs. Endogenous insulin and glucagon secretion were inhibited by somatostatin (0.8 micrograms X kg-1 X min-1), and intraportal replacement infusions of insulin (213 +/- 28 microU X kg-1 X min-1) and glucagon (0.65 ng X kg-1 X min-1) were given to maintain basal hormone concentrations for 2 h (12 +/- 2 microU/ml and 108 +/- 23 pg/ml, respectively). The glucagon infusion was then increased 2-, 4-, 8-, or 12-fold for 3 h, whereas the rate of insulin infusion was left unchanged. Glucose production (GP) was determined with 3-[3H]glucose, and gluconeogenesis (GNG) was assessed with tracer (U-[14C]alanine conversion to [14C]glucose) and arteriovenous difference (hepatic fractional extraction of alanine, FEA) techniques. Increases in plasma glucagon of 53 +/- 8, 199 +/- 48, 402 +/- 28, and 697 +/- 149 pg/ml resulted in initial (15-30 min) increases in GP of 1.1 +/- 0.4 (N = 4), 4.9 +/- 0.5 (N = 4), 6.5 +/- 0.6 (N = 6), and 7.7 +/- 1.4 (N = 4) mg X kg-1 X min-1, respectively; increases in GNG (approximately 3 h) of 48 +/- 19, 151 +/- 50, 161 +/- 25, and 157 +/- 7%, respectively; and increases in FEA (3 h) of 0.14 +/- 0.07, 0.37 +/- 0.05, 0.42 +/- 0.04, and 0.40 +/- 0.17, respectively. In conclusion, GNG and glycogenolysis were similarly sensitive to stimulation by glucagon in vivo, and the dose-response curves were markedly parallel.

Alanine↗
PubMed1986

Naltrexone blocks the post-shock increase of ethanol consumption.

Attention has recently focused on the possibility of an interaction between ethanol and the endorphin system. In this study the opiate blocker naltrexone prevents the expected post-shock increase of ethanol consumption. This provides further evidence that endogenous opiates are involved in the voluntary drinking of ethanol in rats.

Alcohol Drinking↗
PubMed1986

Systematic risk factor screening and education: a community-wide approach to prevention of coronary heart disease.

Within a community-wide heart disease prevention effort, it was hypothesized that personalized risk factor screening and education would result in modified health behaviors and reduced risk factor levels for coronary heart disease. Adults from a population sample were randomized to a community-wide screening and education program or were excluded from that program for 1 year. At the end of that year, both groups were measured for risk factor levels and related health behaviors. Those who received the screening and education program had significantly lower risk factor levels and other evidence of health behavior change, including lower blood cholesterol (206.9 vs 211.5 mg/dl), lower diastolic blood pressure (68.7 vs 70.0 mm Hg), lower resting heart rate (71.4 vs 72.7 bpm), and increased selection of low-fat and low-sodium meals in local restaurants. These data suggest that systematic risk factor screening and education may result in lower population risk for coronary heart disease.

Adult↗
PubMed1986

Imaging of the bowel wall. Computed tomography and fat density oral-contrast agent in an animal model.

In this study, we reassessed the problems encountered in computed tomographic (CT) examinations performed with conventional bowel preparations, and developed a fat density oral contrast in dogs. Conventional high-density agents, water, fat (negative) density, and air were administered using a nasogastric tube to eight dogs (25 separate CT scans). Optimal and consistent identification of the gastrointestinal (GI) tract and mural visualization were achieved with 400 ml of 12.5% to 50% corn oil emulsions administered in four hourly divided doses. Mild diarrhea was observed with the 50% concentration only, but no untoward effect was noted clinically with 25% and 12.5% emulsions. Mixing the negative (fat) density oral contrast with the GI contents produced conditions optimal for high-CT contrast resolution of the GI wall. Standard intravenous administration of iodinated contrast agent enhanced mural visualization and, in conjunction with dynamic scanning, time density curves. This suggests that vascular perfusion could be portrayed. This animal model may be used for the experimental evaluation of a number of GI abnormalities, including ischemic, neoplastic, and inflammatory conditions.

Administration, Oral↗