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Biomedical subjects

M Bayley

Publications and source records attributed to M Bayley.

11 recordsLinked to original sources
PubMed1999

Water vapor absorption in arthropods by accumulation of myoinositol and glucose

Hydrophilic soil arthropods have been thought to respond to soil desiccation exclusively by migrating to deeper soil layers. Numerous studies have shown that their survival below 90 percent relative humidity dry weight, is limited to hours. However, little attention has been paid to physiological adaptations to more realistic desiccation regimes, such as at the permanent wilting point of plants (98.9 percent relative humidity). A water vapor absorption mechanism is described that allows a common soil collembolan, Folsomia candida, to remain active down to below the permanent wilting point. A reevaluation of the water physiology of this widespread and diverse animal group is required.

Journal Article↗
PubMed1999

Guppy sexual behavior as an effect biomarker of estrogen mimics.

There is widespread concern that some environmental chemicals can reduce the reproductive capability of humans and wildlife by mimicking natural estrogens and disrupting endocrine function. This potential threat to animal populations posed by xenoestrogens has, hardly surprisingly, been met by an intensive global effort to identify and develop biomarkers suitable for screening chemicals for estrogen mimicking capacity. Despite this effort, there are few biomarkers capable of linking exposure to xenoestrogens to impaired reproductive capability. The reproductive success of most animals depends strongly on the ability to perform the appropriate sexual behavior. The sexual display of the male guppy is strongly linked to reproductive success and is readily quantified under laboratory conditions. This preliminary study demonstrates that exposure of adult male guppies to water weakly contaminated with either natural estrogen (17beta-estradiol) or the xenoestrogen (4-tert-octylphenol) causes a dramatic decrease in the rate and intensity of sexual display. It is concluded that quantitative analysis of the sexual display of male guppies holds great promise as a biomarker at the organismal level for the effects of estrogen mimicking xenobiotics.

Animals↗
PubMed1995

Elevated copper levels during larval development cause altered locomotor behavior in the adult carabid beetle Pterostichus cupreus L. (Coleoptera: Carbidae).

It is generally believed that copper causes changes in carabid communities indirectly by reducing food availability, because these animals are frequently found to have only slightly elevated metal contents even close to pollution sources. Using computer-centered video tracking, the locomotor behavior of adult Pterostichus cupreus carabid beetles was quantified after being raised on copper-contaminated food and soil during larval development. Copper was found to have an acute toxic effect measured in larval mortality, to cause a slight increase in the developmental period of males, but not to effect the emergence weights of adults of either sex. This toxic effect on the larvae was preserved through pupation to the surviving adults, which were normal in size and appearance, but displayed a dramatically depressed locomotor behavior. Copper analysis of these adults revealed that copper levels were either the same as or only slightly elevated in comparison with controls. The findings suggest that the altered locomotor behavior is associated with copper-induced internal structural damage during larval development and therefore expresses a prolonged or permanent effect. Such changes in locomotor behavior are likely to reduce the fitness of the animal under field conditions.

Animals↗
PubMed1995

N of 1 study: amantadine for the amotivational syndrome in a patient with traumatic brain injury.

Severe amotivation, apathy, and abulia, significantly retard rehabilitation following traumatic brain injury. Preliminary, uncontrolled research has suggested possible benefit with amantadine for this behavioural syndrome. This N of 1, double-blind, placebo-controlled study employed amantadine 100 mg three times daily in one such patient. Therapists and nurses completed inventories scoring efforts towards initiation of therapeutic activities during each session, progress in therapy, and participation in therapy. Four treatment periods (two active medication, two placebo), of 2 weeks duration, were completed. Across four therapists, and for both treatment pairs, the average effect score increased from 0.86 on placebo to 1.74 on amantadine (possible range 0-6, 3 = 'average'). There were no side-effects. The study suggests possible benefit with amantadine for patients with amotivational syndrome after traumatic brain injury; a randomized clinical trial appears warranted and required.

Adult↗
PubMed1993

Effects of the pyrethroid insecticide Cypermethrin on the locomotor activity of the wolf spider Pardosa amentata: quantitative analysis employing computer-automated video tracking.

Wildlife in areas surrounding arable land is almost inevitably exposed to pesticide spray. Even at doses far below the lethal level, this presents a threat to vulnerable species. The widely used pyrethroid insecticides, including Cypermethrin, are known for their direct effect on the locomotor apparatus of animals, inducing varying degrees of paresis. Quantitative measurements of the voluntary locomotion of animals express an integrated response to changes in biochemical and physiological processes. In the present study, the effect of Cypermethrin on the voluntary locomotion of the wolf spider Pardosa amentata was quantified in an open field setup, using computer-automated video tracking. Each spider was recorded for 24 hr prior to pesticide exposure. After topical application of 4.6 ng of Cypermethrin, the animal was recorded for a further 48 hr. Finally, after 9 days of recovery, the spider was tracked for 24 hr. Initially, Cypermethrin induced an almost instant paralysis of the hind legs and a lack of coordination in movement seen in the jagged and circular track appearance. This phase culminated in total quiescence, lasting approximately 12 hr in males and 24-48 hr in females. Following paresis, the effects of Cypermethrin were evident in reduced path length, average velocity, and maximum velocity and an increase in the time spent in quiescence. Also, the pyrethroid disrupted the consistent distributions of walking velocity and periods of quiescence seen prior to pesticide application. Our results suggest that normal locomotion had returned 9 days after Cypermethrin application, but that recovery of high velocities was still incomplete.

Animals↗
PubMed1993

Quantitative analysis of spider locomotion employing computer-automated video tracking.

The locomotor activity of adult specimens of the wolf spider Pardosa amentata was measured in an open-field setup, using computer-automated colour object video tracking. The x,y coordinates of the animal in the digitized image of the test arena were recorded three times per second during four consecutive 12-h periods, alternating between white and red (lambda > 600 nm) illumination. Male spiders were significantly more locomotor active than female spiders under both lighting conditions. They walked, on average, twice the distance of females, employed higher velocities, and spent less time in quiescence. Both male and female P. amentata were significantly less active in red light (simulated dark environment) than in white light. The results also revealed that P. amentata administers its walking velocity and periods of quiescence according to consistent distributions, which can be approximated by simple mathematical expressions. It was found that this species spends exponentially decreasing time at increasing velocities. The number of quiescent periods, however, follow a power decay distribution at increasing quiescent period duration.

Acceleration↗
PubMed1977

Acute copper intoxication. Pathophysiology and therapy with a case report.

We report a case of cupric sulfate intoxication in a child who had a serum copper level of 1,650 mug/100 ml. His course was accompanied by hemolytic anemia and renal tubular damage. We review the pathophysiology of copper metabolism and intoxication. We also review modes of therapy, with specific reference to the initial approach, using dimercaprol (BAL) and edetic acid rather than penicillamine.

Acute Disease↗
PubMed1975

Fatal overdose from Bendectin.

A three-year old male ingested approximately 100 tablets of Bendectin. He developed tonic-clonic seizures followed by cardiac arrest. Toxicologic analysis yielded high levels of doxylamine, dicyclomine, and pyridoxine in blood, peritoneal fluid, and tissue homogenates. The antihistamine, doxylamine succinate appears to be the toxic constituent. Analytical methods used to document the case are herein described.

Accidents, Home↗
PubMed1975

Report of a fatal, acute tripelennamine intoxication.

A death resulting from tripelennamine overdose in a 19-year-old male Caucasian is reported. The patient died 7 h after ingesting approximately twenty 50-mg tripelennamine tablets. A concentration of 1.0 mg/100 ml was found in the blood. All tissue concentrations were measured by ultraviolet spectroscopy and verified by gas-liquid chromatography. Significant findings included pulmonary edema and multiple small petechial hemorrhages in the soft tissue of the scalp.

Adult↗