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Biomedical subjects

M Allen

Publications and source records attributed to M Allen.

At least 253 records · Page 14Linked to original sources
PubMed1983

Variations in hand position, cerebral lateralization, and reading ability among right-handed children.

A group of 121 right-handed children between the ages of 7 and 9 with a range of hand positions between normal and inverted were assessed for verbal and visuospatial lateralization and reading comprehension. Results indicate that (a) children with a normal hand position tended to be more verbally lateralized than children with nonnormal positions, although the effect was not strong or always consistent, (b) the closer the child was to the normal position, the higher the child's reading scores, and (c) poor readers were as lateralized for verbal and visuospatial functions as were good readers. Coupled with the results of previous research, these findings suggest that hand position indexes both maturation and lateralization, and that the relationship between hand position and reading is primarily mediated by the former.

Age Factors↗
PubMed1983

A modified method for measurement of radiotracer permeation across the rat blood--brain barrier: the problem of correcting brain uptake for intravascular tracer.

A modified technique to assess integrity of the rat blood--brain barrier is described in which a poorly permeating radiotracer is injected intravenously and its net permeation across the cerebral vasculature in 30 min is related to its time-averaged level in the circulation. At the termination of experiments, direct carotid arterial perfusion clears blood from brain in 30 s and permits measurement of the tracer level in brain parenchyma without correction for intravascular tracer. Constant-rate withdrawal of a single arterial blood sample throughout the period of tracer circulation replaces the need for repeated blood sampling and graph plotting to determine the time-integrated plasma tracer level. During the first 2-3 min following intravenous injection of [3H]mannitol or [14C]sucrose, permeation across the barrier occurred at a rate substantially greater than that measured for a 30 min circulation time. The relatively rapid uptake of these tracers into brain during the first few minutes after injection would explain in part why estimates of regional blood volume, calculated from ratios of brain vs blood tracer concentration after short circulation times, were much higher than values determined using [51Cr]erythrocytes.

Animals↗
PubMed1983

Prospective immunological assessment of arthritis induced by rubella vaccine.

A prospective study was carried out to correlate the development of joint symptoms after rubella immunization with pre- and post-immunization rubella-specific immunological responses. Arthralgia or arthritis or both occurred in 10 of 37 adult female volunteers at a mean time of 17.0 days after immunization with the RA 27/3 rubella vaccine. All individuals studied before immunization were seronegative for rubella by either the hemagglutination inhibition or the single radial hemolysis technique. In contrast, rubella enzyme-linked immunosorbent assay or lymphoproliferative responses or both were positive in 27 of 37 (73%) individuals tested before receiving the vaccine. Rubella enzyme-linked immuno-sorbent assays carried out before immunization were positive at high levels (mean E = 0.536) in four individuals who developed recurrent episodes of arthritis after administration of the vaccine while remaining at low levels preimmunization in subjects who developed transient arthralgia (E = 0.238) or no joint manifestations at all (E = 0.288). These data provide preliminary evidence suggesting that rubella vaccine-associated arthritis may occur as a consequence of secondary, rather than primary, infection with rubella virus and that the presence of circulating, nonneutralizing rubella antibody may enhance the development or severity (or both) of the associated postinfection joint manifestations. Assessment of rubella hemagglutination inhibition, hemagglutination inhibition (immunoglobulin M), and enzyme-linked immunosorbent assay serological responses at 6 weeks and 6 months post-immunization revealed no significant differences between patients who developed and those who did not develop joint manifestations. Rubella lymphoproliferative responses were elevated at 6 weeks post-immunization in the group developing arthralgia or arthritis or both, with no difference between the groups observed at 6 months post-immunization.

Adult↗
PubMed1983

Activity-generated endorphins: a review of their role in sports science.

Endorphins are a collection of opioid-like neurochemicals scattered throughout the nervous system which have profound effects upon the neurohormonal regulatory mechanisms of the brain-stem and all that it controls. Endorphins, primarily beta-endorphin, are elevated with exercise, which places athletic activity in a pivotal role to modulate--usually by inhibition--diverse physiologic functions. They are important in the adaptative process of humans, and models of endorphinergic effects are presented which help to relate their role from the intra-cellular to the macro-function. Explanations and some speculations are offered concerning other non-athletic manipulations of endorphins and how they may be used in sports. Some hazards to athletic performance may be related to endorphinergic effects. Somewhat like their exogenous counterpart (morphine), endorphins may be part of an endogenous euphoric reward system, and as such would reinforce behavior conductive to the perpetuation of their elevation.

Acupuncture Therapy↗
PubMed1983

Stimulation of canine gastric mucus secretion with intraarterial acetylcholine chloride.

This study was undertaken to develop an easily reproducible gastric mucus secretory model that would elicit maximal mucus secretion without gross mucosal injury. Acetylcholine chloride (50 micrograms/min) was infused intraarterially into a chambered wedge of exteriorized corpus mucosa via a branch of the gastrosplenic artery for 1 h. An alkaline secretion, pH 8.28 +/- 0.48, was produced and consisted of water (40-60 ml/h), electrolytes (Na+, K+, Cl-), soluble mucus, and a mucus gel (4-10 mm thick). Mucus was quantitated by monitoring the secretion of newly synthesized glycoproteins, radiolabeled with [3H]glucosamine and sodium [35S]sulfate. A transient increase in deoxyribonucleic acid efflux, and mucosal permeability as measured by albumin movement, occurred, both of which were reversible upon cessation of acetylcholine chloride infusion. The gastric epithelium was normal histologically, except for occasional apical vacuoles present only in interfoveolar mucus cells. Transmission electron microscopy revealed diminished numbers of apical mucus granules and greatly enlarged intercellular spaces in some mucus cells. Histochemically, the mucus gel consisted of alternating layers of sulfate-rich and sulfate-poor glycoproteins. This model provides a copious amount of mucus that is ideal for biochemical analysis and determination of mucus structure. It allows one to distinguish soluble mucus, gel mucus, and unsecreted granule-bound mucus.

Acetylcholine↗
PubMed1983

Naloxone eye drops reverse the miosis in runners--implications for an endogenous opiate test.

Naloxone 0.16% ophthalmic drops or placebo drops were self-administered to one eye by 13 runners 250 times in a double-blind fashion over three weeks of various intensities and durations of running. An increasing incidence of miosis after running and ipsilateral mydriasis after the naloxone eye drops were administered was noted to correlate with increased run durations. During 34 runs of over 30 minutes duration, 20 subject runs (59%) developed miosis in both eyes and mydriasis in the eye treated with naloxone, but none of 10 subject runs over 30 minutes (9 of which showed miosis) developed mydriasis after placebo drop administration. Calculations (means, SEM) of pupil sizes in various run durations revealed an increased occurrence of miosis which was reversed with naloxone in over 30 minute runs at a significance level greater than 0.005 (single tailed "t" test). It is suggested that exercise generated endogenous opiates cause pupillary miosis, and that ophthalmic naloxone to one eye can block this exercise pupillary effect resulting in ipsilateral mydriasis. Suggestions are given for a simple "Naloxone Anisocoria Test" for the presence or absence of elevated endogenous opiates.

Adolescent↗
PubMed1982

Pulsed Doppler echocardiography in the diagnosis and estimation of severity of aortic insufficiency.

Detection and estimation of the degree of chronic aortic insufficiency with pulsed Doppler echocardiography was attempted in 27 patients documented to have aortic insufficiency on aortography. Twenty-five patients had associated aortic stenosis or mitral valve disease, or both. A disturbed diastolic flow within the left ventricular outflow tract was recorded in all but one patient (Doppler sensitivity 96 percent). Aortic insufficiency was clinically undetected in three patients (clinical sensitivity 89 percent). In a small number of patients Doppler echocardiography also appeared to be highly specific for this disorder. The Doppler technique estimated the degree of aortic insufficiency by assessing the distribution of diastolic flow within the outflow tract and the body of the left ventricle. A significant correlation between the Doppler method and the angiographic estimation of aortic insufficiency was found (r = 0.88, p less than 0.01).

Adult↗
PubMed1982

Continuous assessment of knee function and patient mobility.

A technique is described for measuring and analysing the load profile of the knees during daily routine. The method has been used on patients with chronic arthritis of the knee, both before and after joint replacement. Results are presented, and the logistics of carrying out such work are discussed. The method is applicable to joints other than the knee, diseases other than arthritis, and treatments other joint replacement.

Aged↗