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Biomedical subjects

M Wall

Publications and source records attributed to M Wall.

At least 145 records · Page 8Linked to original sources
PubMed1978

The variability of the protection factors for sunscreening products.

The variation of the preotection factors for a sunscreening product as determined for different test subjects can be described by a logarithmic normal distribution. It is therefore more appropriate to use logarithmically transformed data for statistical analyses. By means of an analysis of variance it was shown that the influence of the subjects is responsible for only 12% of the total variance, whereas the remaining 88% is due to experimental error. Therefore, the difficulties in determining precise protection factors must be ascribed to deficiencies in the method itself. It was further concluded that correcting the protection factors with respect to a simultaneously measured reference preparation is not a means of improving the precision of the data. The reference substance, if it is included in every measuring series may, however, be used to check the long-term constancy of the method and to compare results from different laboratories.

Analysis of Variance↗
PubMed1976

Cardiac pacemaker.

Explore the source record for details and available documents.

Anti-Arrhythmia Agents↗
PubMed1976

Analysis of cardiac chronotropic responses to some autonomic blocking agents in conscious trained dogs.

The changes of heart rate in response to i.v. administration of methylatropine (0.5 mg/kg) and/or propranolol (2 mg/Kg) or practolol (2.5 mg/Kg) were studied in conscious trained dogs. Cholinergic blockade alone or combined blockade of sympathetic and parasympathetic effector systems resulted in cardiac acceleration. Conversely, beta-adrenoceptor antagonism with either propranolol or practolol reduced heart rate. The data were analysed by means of a new method, whereby the heart (HRN) of the dog is considered to be the product of the intrinsic heart rate (HR0) and 3 further factors: HRN-HR0 times S times V times W (Multiplicative model). 2 of these factors represent the tonic sympathetic (S) and parasympathetic (V) influences, whereas the third (W) represents the sympathetic-parasympathetic interaction. This type of analysis reveals that W was approximately 1, i.e., the sympathetic-parasympathetic interaction did not play any significant role in determining the heart rate of conscious resting dogs (HRN = HRO-S-V-W = HRO-S-V). The change of heart rate due to the action of parasympathetic system (-53% of the intrinsic heart rate) was more important than the change caused by the action of the sympathetic system (26% of the intrinsic heart rate).

Animals↗
PubMed1976

Analysis of cardiac chronotropic responses to diazepam and bromazepam in conscious trained dogs.

In conscious trained dogs, administration of bromazepam (0.3 mg/kg p.o.) or diazepam (0.3 and 1.0 mg/kg p.o.) had no influence on heart rate. A higher dose (10 mg/kg p.o.) of two benzodiazepines elicited a positive chronotropic effect which was rapid in onset and of long duration. The beta-adrenoceptor blocking agent practolol (2.5 mg/kg i.v.) did not revert heart rate after the benzodiazepines to the same level as in controls, indicating that the tachycardia was not produced by an increase in sympathetic outflow to the heart. For diazepam, a sympathetic--parasympathetic interaction cannot be excluded. However, diazepam and bromazepam significantly reduced the tachycardia which is normally observed after administration of methylatropine (0.5 mg/kg i.v.) alone or in combination with practolol. In anaesthetized dogs, bromazepam failed to modify the heart rate responses to electrical stimulation of cardiac vagal or sympathetic nerves, excluding an action on this compound on ganglionic transmission and cardiac cholinoceptors and adrenoceptors. It is concluded that high doses of diazepam and bromazepam influence the heart rate of conscious dogs in a biphasic way. Firstly, they cause a central reduction of vagal tone to the heart resulting in tachycardia. Secondly, the two drugs decrease the cardiac pacemaker rate directly. Since the overall effect is tachycardia, the central action is more pronounced.

Administration, Oral↗
PubMed1971

Protective isolation in single-bed rooms: studies in a modified hospital ward.

Studies were made in a modified hospital ward containing 19 beds, 14 of them in the open ward, one in a window-ventilated side-room, two in rooms with partial-recirculation ventilators giving 7-10 air changes per hour, and two in self-contained isolation suites with plenum ventilation (20 air changes per hour), ultra-violet (UV) barriers at doorways and airlocks.Preliminary tests with aerosols of tracer bacteria showed that few bacteria entered the plenum or recirculation-ventilated rooms. Bacteria released inside mechanically ventilated cubicles escaped into the corridor, but this transfer was reduced by the presence of an airlock. UV barriers at the entrance to the airlock and the cubicle reduced the transfer of bacteria from cubicle to corridor.During a period of 4 years while the ward was in use for surgical and gynaecological patients, the incidence of post-operative sepsis and colonization of wounds by multiple-resistant Staphylococcus aureus was lower (though not significantly lower) in the plenum-ventilated rooms than in the open ward, the recirculator-ventilated cubicles and the window-ventilated cubicles. Nasal acquisition of multiple-resistant Staph. aureus was significantly less common in the plenum-ventilated than in the recirculator-ventilated cubicles and in the other areas. Mean counts of bacteria on settle-plates were significantly lower in the plenum-ventilated cubicles than in the other areas; mean settle-plate counts in the recirculator-ventilated cubicles were significantly lower than in the open ward and in the window-ventilated side-room; similar results were shown by slit-sampling of air. Mean settle-plate counts were significantly lower in all areas when the ward was occupied by female patients. Staph. aureus was rarely carried by air from plenum-ventilated or other cubicles to the open ward, or from the open ward to the cubicles; though staphylococci were transferred from one floor area to another, they did not appear to be redispersed into the air in sufficient numbers to infect the patients. Ultra-violet irradiation caused a significant reduction in the total and staphylococcal counts from the floors of airlocks, and a significant reduction of total counts in the air.

Air Microbiology↗
PubMed1968

Changing use of hospital beds by the elderly.

Recent changes in the age structure of the mental hospital population in the Birmingham Region are first examined. The proportion of patients aged 65 and over of the total in residence has steadily increased and at the end of 1967 was 43%, and more than half the female patients are now in this age group.Admissions of elderly persons to both psychiatric and general hospitals have increased, and these hospitals have responded to the increased demand on their services by increasing bed-turnover rates. During 1967 on average one-fifth of all patients occupying beds for acute cases (excluding maternity) were 65 years of age or over.In the geriatric hospital service, on the other hand, accommodation per head of the population decreased between 1961 and 1967, as did the total annual number of admissions and the rate of turnover. This suggests that the geriatric service is overstretched and that it is under-organized, understaffed, or undercapitalized-possibly all three. The enforced expedient of admitting "excess" elderly patients to mental hospitals does not recommend itself.

Age Factors↗
PubMedDate not supplied

Reducing maternal smoking and relapse: long-term evaluation of a pediatric intervention.

BACKGROUND: Pediatric well-care visits provide a clinical opportunity to counsel new mothers about their smoking and the deleterious effects of environmental tobacco smoke (ETS) on infant health. METHODS: Forty-nine Oregon pediatric offices enrolled 2,901 women who were currently smoking or had quit for pregnancy, using a brief survey at the newborn's first office visit. Randomly assigned offices provided advice and materials to mothers at each well-care visit during the first 6 months postpartum to promote quitting or relapse prevention. RESULTS: The intervention reduced smoking (5.9% vs 2.7%) and relapse (55% vs 45%) at 6-month follow-up, but logistic regression analysis at 12 months revealed no significant treatment effect. The intervention had a positive effect on secondary outcome variables, such as readiness to quit and attitude toward and knowledge of ETS. Multiple logistic regression analysis indicated that husband/partner smoking was the strongest predictor of maternal quitting or relapse. CONCLUSIONS: A pediatric office-based intervention can significantly affect smoking and relapse prevention for mothers of newborns, but the effect decreases with time. Consistent prompting of the provider to give brief advice and materials at well-care visits could provide a low-cost intervention to reduce infant ETS exposure.

Cost-Benefit Analysis↗