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Biomedical subjects

B Rothwell

Publications and source records attributed to B Rothwell.

At least 19 recordsLinked to original sources
PubMed1999

Postinspiratory activity of the parasternal and external intercostal muscles in awake canines.

Previous studies have shown in awake dogs that activity in the crural diaphragm, but not in the costal diaphragm, usually persists after the end of inspiratory airflow. It has been suggested that this difference in postinspiratory activity results from greater muscle spindle content in the crural diaphragm. To evaluate the relationship between muscle spindles and postinspiratory activity, we have studied the pattern of activation of the parasternal and external intercostal muscles in the second to fourth interspaces in eight chronically implanted animals. Recordings were made on 2 or 3 successive days with the animals breathing quietly in the lateral decubitus position. The two muscles discharged in phase with inspiration, but parasternal intercostal activity usually terminated with the cessation of inspiratory flow, whereas external intercostal activity persisted for 24.7 +/- 12.3% of inspiratory time (P < 0.05). Forelimb elevation in six animals did not affect postinspiratory activity in the parasternal but prolonged postinspiratory activity in the external intercostal to 45.4 +/- 16.3% of inspiratory time (P < 0.05); in two animals, activity was still present at the onset of the next inspiratory burst. These observations support the concept that muscle spindles are an important determinant of postinspiratory activity. The absence of such activity in the parasternal intercostals and costal diaphragm also suggests that the mechanical impact of postinspiratory activity on the respiratory system is smaller than conventionally thought.

Animals↗
PubMed1992

Knowledge of AIDS and HIV among various groups.

To date, no cure has been found for HIV/AIDS. Prevention has therefore been the immediate principal aim and a didactic approach has been given a primary role. Studies from the USA indicate that knowledge level may be dictated by membership of particular subcultural groups and the perceived relevance of HIV/AIDS to these groups. This study investigates knowledge among four groups: homosexual; single heterosexual; IV drug users; and a 'married' group. Results indicate some gaps in knowledge and a greater knowledge base among one of the high risk groups, the homosexual group.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Visual field differences in the magnitude of the Oppel-Kundt illusion vary with processing time.

Three experiments were performed to investigate hemispheric differences in susceptibility to the Oppel-Kundt illusion presented tachistoscopically to the two visual hemifields. Experiment 1 used a successive comparison mode, in which 16 undergraduate students indicated whether the second of two successive extents looked shorter or longer than the first. Experiment 2 (20 under-graduates) and Experiment 3 (1 commissurotomy patient) required judgments of two extents presented simultaneously. The first experiment found no significant visual field differences, although females were more susceptible than males. In the second experiment, the illusion magnitude was greater in the left visual field, and in the third experiment, it was greater in the right visual field. Post hoc analyses resolve the conflicting results and show that in all three experiments, the susceptibility of the right hemisphere declined more than that of the left hemisphere during illusion processing. An interpretation is offered in terms of two parallel processes, one that is fast, uses feature extraction, and is performed more effectively in the left hemisphere, and one that is slow, uses visuospatial analysis to compute distances between parts of the illusion figure, and is performed more effectively in the right hemisphere.

Adolescent↗
PubMed1986

A fine structural study of the turkey harderian gland.

The ultrastructure of the turkey Harderian gland is described and the findings support previous histological descriptions of the gland. The gland is a compound tubulo-acinar structure composed of characteristic bipolar epithelial cells providing a predominantly merocrine secretion to the lumina. In the basal aspect of the cell, aggregations of non-secretory lipid-like droplets were evident and apically, the secretion was mucoid. The cells had abundant mitochondria, granular endoplasmic reticulum, ribosomes and a complex network of Golgi elements. In the subepithelial regions, myoepithelial cells and large numbers of plasma cells were seen. Within the granular endoplasmic reticulum cisternae of the epithelial cells, fibrillary or crystalline rods in some instances measuring up to 10 micron in length, with a 7.0 nm repeat pattern, were frequently seen.

Animals↗
PubMed1978

The use of osmolality as an aid to establishing consistent fixation quality: studies on the kidney of the domestic fowl.

1. Using the proximal convoluted tubule of the fowl kidney as indicator tissue the immersion application of fixatives of differing composition and osmolality was studied. 2. The best results were obtained with Dalton's buffered osmium tetroxide and with sodium cacodylate buffered glutaraldehyde followed by osmium post-fixation. 3. The most satisfactory component concentrations in both cases were those which most reproduced a total osmolality close to that of fowl plasma. With both types of fixation the ultrastructural image of the kidney tubule was sensitive to changes in fixative osmolality and differences were clearly identified over a 30 to 50 mOsm range. 4. With glutaraldehyde/osmium double fixation it was found that it was the total osmolality of the glutaraldehyde buffer combination that was to be considered in a study of osmolotic effects, not the osolality of the buffer vehicle alone. 5. The 30 to 50 mOsm difference in fixative osmolality that was able to be detected by studying the image of the kidney tubule was of the order of magnitude commonly experienced as experimental error in the laboratory as a result of changes in reagent batches or error in making up the solutions. The measurement of osmolality therefore provides an ideal quality control to the laboratory make-up of fixative solutions.

Animals↗
PubMed1977

The ultrastructure of the follicle wall of the domestic fowl during the phase of rapid growth.

The development of a standard technique for fixing the developing follicle for ultrastructural studies is described. 2. The follicle wall is shown to be a multi-layered structure which exhibits a number of morphological changes concomitant with yolk protein transfer, the most significant of which are the intercellular channels which form between the granulosa cells during the fast phase of protein transfer.

Animals↗
PubMed1975

Designation of the cellular component of the peritubular boundary tissue of the seminiferous tubule in the testis of the fowl (Gallus domesticus).

1. The boundary tissue surrounding the testis has a mechanical function in sperm transport as well as being a significant element in the blood-testis barrier. 2. The designation of the cellular component is suggested to be myofibroblast thus indicating fibroblastic and contractile myoid cell features and suggests their dual functional role.

Animals↗