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Biomedical subjects

S MacDonald

Publications and source records attributed to S MacDonald.

90 records · Page 5Linked to original sources

Egg-laying and hatching rhythms in the monogenean Diplozoon homoion gracile from the southern barbel (Barbus meridionalis).

Diplozoon homoion gracile from the southern barbel (Barbus meridionalis) displays an egg-laying and an egg hatching rhythm, the latter being more clearly defined. Egg laying continues both day and night but significantly more eggs are laid at night. The oncomiracidia hatch at dusk. If parasite eggs are eaten by the host they pass through the gut undamaged and hatch normally.

Animals↗

Antibacterial therapy in general medical wards.

Information from a comprehensive drug surveillance programme is analysed to provide details of antibacterial drug use in medical wards. Some 28% of patients received antibacterial therapy, usually for the treatment of respiratory or urinary tract infections. The agents most frequently prescribed were ampicillin, co-trimoxazole and tetracyclines. Overall, 11% of recipients experienced one or more adverse effect of therapy. No significant bacterial growth was obtained from some 40% of specimens of sputum sent from patients. A plea is made for more rational use both of sputum culture in the investigation of patients with respiratory infection and of antibiotics in their treatment.

Ampicillin↗

Controlled study of child health supervision: behavioral results.

Extensive child health supervision, with emphasis on counseling and anticipatory guidance, was provided for the first three years of life to an experimental series of 47 normal first-born black infants from low-income families living in the environs of Children's Hospital in Washington, D.C. The mothers were unmarried schoolgirls in normal physical and mental health. A control series consisted of 48 similar mother-child dyads from the same area. Data were collected, in part by an outside evaluator, at yearly intervals on both experimental and control series in a form suitable for coding on computer cards. Comparison of differences in behavioral results between the two series showed statistically significant findings in favor of the experimental children, as well as numerous favorable trends during the first six years of life. Positive effects became evident in diet and eating, habits, in some developmental problems of growing up (such as toilet training), and in certain abstract qualities including self-confidence. Significant differences were also noted between the experimental and control mothers for various child rearing practices and personality characteristics. No significant difference or trend favored the control series. We believe that a causal relationship existed between the intervention and at least some of the significant findings.

Black or African American↗

Hatching rhythms in three species of Diclidophora (Monogenea) with observations on host behaviour.

Eggs of three species of Diclidophora were incubated in alternating 12 h periods of light and darkness at 13 degrees C. Eggs of D. merlangi collected at Arbroath hatched during the illumination period with most larvae being recovered in the first 4-6 h; some evidence of a seasonal difference in hatching of these eggs was found. Eggs of D. merlangi collected at Plymouth hatched with a peak of larval recovery in the 2 h period before the light came on. Eggs of D. luscae hatched over 'dusk' while those of D. denticulata hatched after the light was switched off. Neither mechanical disturbance nor the proximity of host tissue caused hatching in D. merlangi or D. luscae. Observations on the behaviour of the host fishes suggest that the hatching rhythms are adapted to specific host behaviour patterns.

Animals↗

Increased absolute light sensitivity in Himalayan mice with cold-induced ocular pigmentation.

Controversy over the relationship between ocular pigmentation and absolute dark-adapted light sensitivity has persisted for over two decades. Previous electrophysiological experiments in hypopigmented mammals (mice, rats, rabbits) show increased thresholds in the dark-adapted state proportional to the deficit in ocular melanin. Animals with the least amount of ocular melanin have the most elevated thresholds. Dark-adapted thresholds in hypopigmented mice show similar threshold elevations in behavioral tests. The present study extends these findings to show that a specific increase in ocular pigmentation results in the converse effect, lowered absolute dark-adapted thresholds. The increase in ocular melanin was accomplished by keeping Himalayan mice in the cold (4 degrees C) for 6 weeks. Himalayan mice (C57BL/6J cH/cH) were compared to black mice (C57BL/6J (+/+)) and albino mice (C57BL/6J c2J/c2J) after 6 weeks at either 4 degrees C or 20 degrees C in 12-h cycling light (<1 cd/m2). The Himalayan mice that were kept in the cold exhibited a 44% increase in ocular melanin compared to Himalayan mice kept at room temperature. Cold rearing did not effect ocular melanin or visual thresholds in control animals (black mice = 10(-5.9) cd/m2 and albino mice = 10(-4.4) cd/m2). In contrast, the Himalayan mice maintained at 4 degrees C had thresholds of 10(-5.7) cd/m2 compared to 10(-5.1) cd/m2 for Himalayan mice kept at 20 degrees C. This represents compelling evidence of a direct relationship between ocular melanin concentration and absolute dark-adapted light sensitivity.

Animals↗

Sodium concentration in saliva along the time course of experimental Coriolis sickness.

Procedures designed to evaluate the severity of motion sickness have included subjective reporting of changes in salivation. In order to increase objectivity, we studied the sodium concentration of saliva, which is directly related to the flow rate. Healthy adults with normal vestibular function underwent a modified Coriolis Sickness Susceptibility Index (CSSI) test, utilizing a staircase profile. Saliva was collected without interrupting the stimulus by means of cotton placed beneath the subject's tongue for one minute. Samples were obtained 5 min prior to stimulation, 30 and 45 min following stimulus onset, and/or upon reaching the "nausea II" endpoint. Saliva for analysis by atomic absorption spectrophotometry was obtained by centrifugation of the cotton. A significant difference in sodium concentration was found between the baseline and 30-min sample (p less than 0.01). Although the amount of salivation was rather variable, the pattern of changes in sodium concentration was similar in all experimental cases.

Adult↗

The effectiveness of directed multisensory stimulation versus non-directed stimulation in comatose CHI patients: pilot study of a single subject design.

In view of the difficulties in finding control groups in sensory stimulation research, a single case methodology was explored. A pilot study was conducted on six comatose CHI patients in a neurosurgical intensive care unit. Each patient was given alternating weeks of directed multisensory stimulation (SDS) and non-directed stimulation (NDS) for half an hour a day in an ABAB single subject design. Eye movement, motor and vocal response to stimulation were recorded using the Sensory Stimulation Assessment Measure (Rader Scale). Comparisons of eye movement and motor responses on the Rader Scale appeared to indicate a greater degree of responsiveness to the SDS as compared with the NDS treatment. Overall improvement levels on the GCS, Rancho Scale and Western Neurosensory Stimulation Profile are discussed. The results are interpreted as indicative of the potential value of using single case methodology in this population, and future research directions are also discussed.

Adolescent↗

Liquid chromatographic method for determination of patulin in clear and cloudy apple juices and apple puree: collaborative study.

A collaborative trial was conducted to validate the effectiveness of a liquid chromatographic (LC) procedure for determination of patulin in both clear and cloudy apple juices and apple puree. The test portion of clear apple juice was directly extracted with ethyl acetate; cloudy apple juice and apple puree were treated with pectinase enzyme before extraction. After back-extraction into sodium carbonate to remove interfering acidic compounds, the extract was dried and concentrated, and patulin was determined by LC with UV detection. Clear and cloudy apple juices, apple puree test samples naturally contaminated with patulin, and blank test samples for spiking with patulin were sent to 14 collaborators in 12 different European countries. Test portions of each of the 3 test sample types were spiked with patulin at 75 ng/g. Recoveries of patulin ranged from 80 to 92%. Based on the results for spiked test samples (blind pairs) and naturally contaminated test samples (blind pairs at 3 levels), the relative standard deviations for repeatability (RSDr) and reproducibility (RSDR) ranged from 8 to 35% and 11 to 36%, respectively. Although HORRAT values of <1.4 were obtained for all 3 matrixes at patulin levels ranging from 26 to 121 ng/g, better performance values (RSDr values 6-10% and RSDR values 11-25%) were obtained for clear and cloudy apple juice spiked above 50 ng/g, which is either the statutory limit or the advisory level for patulin contamination in apple juices in many countries.

Beverages↗

Determination of ochratoxin A in green coffee by immunoaffinity column cleanup and liquid chomatography: collaborative study.

A collaborative study was conducted to evaluate a method using immunoaffinity column cleanup with liquid chromatography (LC) for the determination of ochratoxin A (OTA) in green coffee at levels that could be included in possible future regulations of the European Union. The test portion was extracted with methanol-3% aqueous sodium hydrogen carbonate solution (50 + 50, v/v). The extract was filtered, and the filtrate was diluted with phosphate-buffered saline and applied to an immunoaffinity column containing antibodies specific for OTA. After washing, the toxin was eluted from the column with methanol and quantified by LC with fluorescence detection. Pairs of 4 homogeneous noncontaminated and naturally contaminated materials (mean levels of < 0.12, 2.44, 5.15, and 13.46 ng/g) and blank samples (< 0.12 ng/g) for spiking were sent to 20 participant laboratories from 8 countries. The materials were analyzed according to the method description and all difficulties encountered in the analysis were reported. Statistical analysis was carried out according to the Harmonized Protocol of the International Union of Pure and Applied Chemistry. The relative standard deviation for repeatability (RSDr) ranged from 7.42 to 20.94%, and the relative standard deviation for reproducibility (RSDR) ranged from 16.34 to 29.17%. The method showed acceptable within-laboratory and between-laboratories precision for green coffee materials, as evidenced by HorRat values of < or = 0.85, at the studied range, for spiked and naturally contaminated materials. The mean recovery was 92.8% for green coffee material spiked with OTA at a level of 4.82 ng/g.

Buffers↗

The hatching rhythm of Polystoma integerrimum, a monogenean from the frog Rana temporaria.

1. Eggs of Polystoma integerrimum incubated in alternating periods of light and darkness at a constant temperature hatch in the light. 2. Eggs incubated and hatched in continuous light (10 degrees or 18 degrees C) hatch without a rhythm. Eggs incubated and hatched in continuous darkness at 18 degrees C hatch without any circadian rhythm but fail to hatch at 10 degees C until 1 month later than expected. 3. At both 10 degrees and 18 degrees C the hatching rhythm persists in conditions of continuous light if, during incubation, the eggs were exposed to alternating light and darkness. At 18 degrees C the rhythm appears to persist in total darkness following incubation in alternating light and darkness. At 10 degrees C hatching is blocked. 4. At 10 degrees C if eggs are incubated in alternating periods of light and darkness and then, when hatching begins, these periods are reversed, the hatching rhythm becomes synchronous with the new lighting regime. This may be due to the effect of low temperature. 5. Hatching during the day may have survival value of P. integerrimum since the host tadpoles congregate at this time around the edges of the lakes, the region where the parasite eggs are laid.

Animals↗

Radiographic considerations of Hirschsprung's disease.

This article describes Hirshsprung's disease and its radiographic appearance. It gives important features that must be considered when doing a barium enema on children suspected of having the disease. It also explains why these features must be considered.

Barium Sulfate↗