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Biomedical subjects

S McDowell

Publications and source records attributed to S McDowell.

12 recordsLinked to original sources
PubMed2006

Salmonella surveillance in raw and cooked meat and meat products in the Republic of Ireland from 2002 to 2004.

The food industry, under the regulation of the Department of Agriculture and Food (DAF) in the Republic of Ireland, is required to undertake all microbiological testing in relation to zoonoses control, in laboratories approved by DAF. These laboratories submit a monthly report of all tests undertaken, together with all presumptive Salmonella isolates for confirmation, typing and storage to the Central Veterinary Research Laboratory (CVRL). Details of Salmonella tests on 110,229 raw and 25,189 cooked meat samples from 25 laboratories were recorded over the 3-year period 2002-2004. Salmonella spp. were isolated from 1.0% of the 110,229 raw meat samples and 0.1% of the 25,189 cooked meat samples tested. The percentage of raw meat samples contaminated with Salmonella decreased over the three-year period from 1.2% to 0.9%. There was no seasonal trend in the isolation of Salmonella from any of the meats or meat products. Recoveries of the organism were highest for turkey and chicken meats at 3.1% and 2.8%, respectively, followed by porcine meats at 2.1%. The recoveries were much lower for ovine meats and meat products at 0.2% and bovine meat and meat products at 0.16%.

Animals↗
PubMed1998

Differential effect of a dopaminergic agonist on prefrontal function in traumatic brain injury patients.

We examined the effects of low-dose bromocriptine, a D2 dopamine receptor agonist, on processes thought to be subserved by the prefrontal cortex, including working memory and executive function, in individuals with traumatic brain injury. A group of 24 subjects was tested using a double-blind, placebo-controlled crossover trial, counterbalanced for order. Bromocriptine was found to improve performance on some tasks thought to be subserved by prefrontal function, but not others. Specifically, there was improvement in performance on clinical measures of executive function and in dual-task performance, but not measures that tap the ability to maintain information in working memory without significant executive demands. Also, on control tasks not thought to be dependent on the prefrontal cortex, no improvement on bromocriptine was noted. These results demonstrate a selective effect of bromocriptine on cognitive processes which involve executive control, and provide a foundation for potential therapies for patients with prefrontal damage causing dysexecutive syndromes.

Adult↗
PubMed1997

Working memory impairments in traumatic brain injury: evidence from a dual-task paradigm.

Although many individuals with traumatic brain injury (TBI) perform well on standard neuropsychological tests, they often exhibit marked functional difficulties. The functions which are impaired seem to be analogous to the role of the central executive system (CES) in Baddeley's [Working Memory, 1986, Oxford University Press, New York] widely accepted model of working memory. The purpose of this study was to investigate CES function in individuals with TBI with a dual-task paradigm. We studied 25 non-demented persons who were at various stages in their recovery from severe TBI and compared their performance on a dual-task paradigm to a group of age-matched controls. Our dual-task paradigm measured performance on a simple visual reaction time task both alone (baseline) and during concurrent tasks of articulation or digit span. Subjects were also assessed with other neuropsychological tests of executive function. TBI patients had slower reaction times on the primary task when performed alone (P < 0.05) and greater decrements in performance during dual-task conditions (P < 0.01). They also exhibited significantly greater deficits than control subjects on other measures of executive function. Although correlations between dual-task performance and other executive measures were quite low, principle components analysis suggested that a common factor does exist between these measures. These findings support the conclusion that TBI patients have a working memory impairment that is due to dysfunction of the CES and which may be related to executive function deficits as measured by standard neuropsychological testing.

Adolescent↗
PubMed1997

The role of ranitidine bismuth citrate in significantly reducing the emergence of Helicobacter pylori strains resistant to antibiotics.

BACKGROUND: This study was carried out to investigate the clinical observation that the emergence of antibiotic resistance can be reduced in Helicobacter pylori if agents are administered in combination with bismuth salts. MATERIALS AND METHODS: Two H. pylori clinical isolates were grown on chocolate Columbia agar containing either ranitidine bismuth citrate (RBC) at one-half lethal concentration (8 micrograms/ml) or no drug control for 22 subcultures. After 1, 5, 8, 14, 17, and 22 subcultures, the emergence of antibiotic resistance to metronidazole, clarithromycin, and streptomycin was calculated and statistically analyzed. RESULTS: Acquisition of resistance to metronidazole was reduced significantly for both strains (p = .007 and 0.014) and for one strain against clarithromycin (p = .037). However, spontaneous emergence of resistance to streptomycin was not altered significantly. In an analysis of the effect of long-term exposure of the isolates to RBC, susceptibility to bismuth was unaltered in one strain and had risen by only twofold in the other at experiment termination. CONCLUSION: RBC significantly decreased resistance acquisition in an inherently sensitive strain and also decreased resistance emergence in a strain that readily became metronidazole-resistant.

Anti-Bacterial Agents↗
PubMed1991

The effect of ammonium chloride and sodium bicarbonate ingestion on the physical working capacity at the fatigue threshold.

The purpose of this investigation was to examine the effect of ammonium chloride (NH4Cl) and sodium bicarbonate (NaHCO3) ingestion on the physical working capacity at the fatigue threshold (PWCFT). Eighteen adult males (mean age, SD = 23, 2 years) volunteered for two experiments (experiment 1, n = 9; experiment 2, n = 9). In both experiments, the subjects orally ingested 0.3 g.kg-1 body weight of NH4Cl and NaHCO3 over a 3-h period in random order on days separated by 72 h or more. In experiment 1, following ingestion of the substance, the subjects performed a discontinuous incremental cycle ergometer test to the onset of PWCFT which was estimated from integrated electromyography voltages at the vastus lateralis muscle. In experiment 2, the subjects performed a continuous PWCFT test. The results of these experiments indicated that NH4Cl and NaHCO3 ingestion had no significant (P greater than 0.05) effect on PWCFT (experiment 1: NH4Cl = 257, SD 26 W; NaHCO3 = 256, SD 22 W; t = 0.06; r = 0.866; experiment 2: NH4Cl = 231, 14 W; NaHCO3 = 216, 16 W; t = 1.78; r = 0.857).

Administration, Oral↗
PubMed1991

Genetic damage in a population of slider turtles (Trachemys scripta) inhabiting a radioactive reservoir.

Turtles inhabiting a radioactive reservoir appear to experience genetic damage due to environmental exposure to low concentrations of long-lived radionuclides. Total body burdens for the 50 reservoir turtles examined in the survey ranged from 164.7-4679.3 Bq for cesium-137 and from 462.6-5098.3 Bq for strontium-90. Flow cytometric (FCM) assays of red blood cell nuclei demonstrated significantly greater variation in DNA content for the reservoir turtles than for turtles from a nearby, non-radioactive site. Furthermore, two of the reservoir turtles possessed FCM profiles that are indicative of aneuploid mosaicism. These data strongly suggest that exposure to low-level radiation may involve a sensitive genetic response in a natural population.

Animals↗
PubMed1986

An improved method for detection of ganglionic latency in herpes simplex virus type-1 infected guinea pigs.

A simple method was developed which increased the sensitivity and reliability of detecting latent herpes simplex virus type-1 (HSV-1) in trigeminal ganglia of guinea pigs. Animals were infected with the Shealey strain of HSV-1 immediately following scarification of the cornea and maintained for 30-40 days to ensure that true latency was established. Viral latency was defined as the appearance of infectious virus in ganglia only upon cultivation in vitro. Thus, ganglia from similarly infected animals, homogenized immediately upon removal, did not contain infectious virus. Excised ganglia were incubated intact in high glucose medium and yielded maximal positive results (90-100%) by the twelfth day of incubation. This method was compared with the standard cocultivation technique in which minced fragments of ganglionic tissue were explanted onto Vero cell cultures. Cocultivation yielded a considerably lower latency rate and was more variable (29-57%) than the whole ganglion culture method.

Animals↗