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Biomedical subjects

G W Hall

Publications and source records attributed to G W Hall.

28 records · Page 2Linked to original sources
PubMed1986

Cerebral photosensitisation by haematoporphyrin derivative. Evidence for an endothelial site of action.

Exposure of the cranium to white light in mice that had been given haematoporphyrin derivative (HpD) led to a rapid onset of vasogenic cerebral oedema, cerebral necrosis, coma and death. Selectivity of the initial damage for endothelium was suggested by (a) early breakdown (less than 1 h) of the blood-brain barrier (BBB) as shown by increased permeability to Evans blue (b) separation and increased vesiculation of endothelial cells at 2 h and (c) endothelial cell pyknosis at 3--4 h in small vessels next to apparently undamaged neurones and neuroglia. There was no damage to myelin sheaths, and astrocytes showed only end-feet oedema, a reaction to exudation of protein-rich fluid. Within a few hours of illumination, most cells in the illuminated area were necrotic. Cerebral photosensitivity persisted for at least 12 weeks after a single injection of HpD. Our results suggest that the primary site of damage in the brain is the endothelium of small vessels, and that HpD remains associated with this for a remarkably long time. These findings are relevant to the mechanisms by which photodynamic therapy damages other tissues, including neoplasms, and particularly to the possible application of this treatment to brain tumours.

Animals↗
PubMed1983

Regulatory interactions among the cya, crp and pts gene products in Salmonella typhimurium.

A well-characterized set of pts deletion mutants of Salmonella typhimurium were used to re-evaluate the purported role of the PTS in the inducer exclusion process and in regulation cAMP synthesis. During the course of these studies a class of secondary mutations was isolated which suppress the inhibition of cAMP synthesis caused by pts mutations. These suppressor mutations were traced to the crp locus and tentatively designated as acr (adenylate cyclase regulation) mutations. A new model is proposed in which CRP rather than adenylate cyclase is believed to be the central regulatory element in the catabolite repression phenomenon.

Cyclic AMP↗
PubMed1982

Repression of adenylate cyclase in the genus Bordetella.

Virulent phase I strains of Bordetella pertussis synthesize the regulatory metabolite adenosine 3',5'-cyclic monophosphate (cAMP); whereas, non-virulent phase IV strains are unable to do so. These findings were confirmed and extended using additional strains of B. pertussis as well as strains of Bordetella parapertussis and Bordetella bronchiseptica. Levels of adenylate cyclase activity and subsequent cAMP production were found to correlate. High adenylate cyclase activity during exponential phase was followed by an accumulation of cAMP during late log and throughout stationary phase. Measurements obtained during the X- to C-mode transition process indicated that adenylate cyclase is subject to complete repression.

Adenylyl Cyclases↗
PubMed1977

Study of PFT (parasail) in air training command.

Injuries in pilots following egress from disabled aircraft can be minimized by their ability to maneuver their parachutes during descent and to execute a proper parachute landing fall. USAF pilot and navigator trainees receive extensive ground training in parachute operation and parachute landing falls. They then undergo Parachute Familiarization Training (PFT) during which they experience descents by a parasail after being towed to altitude. The value of PFT was determined by evaluating questionnaires sent to approximately 700 crewmembers, including many ex-prisoners of war, who had made an emergency egress. Areas addressed included contribution of the training to overall confidence, ability to steer the parachute to avoid hazardous obstacles, execution of a proper parachute landing fall, and the role of PFT in avoiding injury or fatality in the post-egress environment. Responses indicated that PFT played a significant role in confidence-building and in avoiding or minimizing post-egress injury.

Aviation↗
PubMedDate not supplied

Coping strategies in families of children with sickle cell disease.

OBJECTIVE: To examine the impact of family environment, morbidity, and socioeconomic status (SES) on coping strategies in families of children with sickle cell disease. DESIGN: A cross-sectional study. METHODS: The study sample consisted of 40 mothers, 24 fathers, 40 patients, and 28 healthy siblings from 40 African-American families, each of which had only one child with sickle cell disease. Data were collected through the use of structured interviews utilizing a demographic questionnaire, the Family Environment Scale (FES), and the COPE. RESULTS: The results indicate that support-seeking coping strategies were employed more often by mothers in more cohesive families and siblings in less cohesive families, while increased growth (resilience) was experienced by siblings in less conflicted families. Patients in more religious families reported greater use of religion as a means of coping. Mothers of mildly affected patients used acceptance more frequently than those of severely affected patients, and fathers of severely affected patients more often sought emotional support. Mothers, fathers, and siblings in low SES families reported greater use of denial than did those in high SES families. CONCLUSION: Additional psychosocial research involving families (including fathers and siblings) dealing with sickle cell disease is needed to facilitate the utilization of adaptive coping strategies, thereby enhancing individual and family adjustment.

Adaptation, Psychological↗