Biomedical subjects

D E Clark

Publications and source records attributed to D E Clark.

166 records · Page 10Linked to original sources

PubMedDate not supplied

Decreasing mortality and morbidity rates after the institution of a statewide burn program.

During the late 1970s, a statewide system for burn treatment and prevention was developed in Maine; it was assumed that such a system would reduce mortality and morbidity rates. To examine the effect of this intervention and the validity of its underlying hypothesis, data for the period from 1973 to 1988 were collected from burn unit registries inside and outside of the state and from hospital discharge abstracts, death certificates, and published sources. In Maine, the annual number of deaths per million persons that resulted from fire- and burn-related injuries declined from 41 in the years 1973-1980 to 25 in the years 1981-1988, which is a significantly greater decrease than for the United States as a whole (p less than 0.001). This decrease could not be explained by changes in the age or urban and rural distribution of the population. The annual number of hospital admissions for treatment of burns (per million persons) in Maine decreased from 401 to 301 over the same period, and patients with more complicated burns were increasingly referred to more specialized centers within and outside of the state. Since a state system was instituted, hospital mortality rates, when grouped by age and burn area, were not significantly different from those reported by the most prominent burn unit in New England. The population-based methods of data collection and linkage that were developed for this investigation may be useful for other studies of injury epidemiology. A statewide burn program appears to have contributed to a reduction in mortality and morbidity rates, primarily through preventive efforts.

Burn Units↗

PubMedDate not supplied

Reappraisal of surgical treatment of traumatic transection of the thoracic aorta.

Since Crawford's report in 1973, repair of traumatic transection of the thoracic aorta without shunt or bypass has emerged as a popular technique which simplifies the operation and avoids use of heparin. Growing evidence, however, indicates that the incidence of paraplegia is higher with this method and may outweigh its advantages. With this in mind, we have examined our experience with 40 patients who underwent repair of aortic transection from 1975-1988. The operated patients in our series all survived. Fourteen were repaired using some type of bypass or shunt, none of whom developed paraplegia. The remaining 26 patients were repaired without a shunt and 9 (34.6%) developed paraplegia or paraparesis (p less than 0.02). Paraplegia was related to aortic occlusion time (p less than 0.002). It did not occur in 11 patients with times less than 27 minutes, but happened in 2 of 8 patients with times between 28 and 35 minutes and in all 7 patients with clamp times over 35 minutes. These data suggest that shunt or bypass should be used in most cases of aortic transection.

Adult↗

PubMedDate not supplied

The effects of chronic cobalt exposure on behavior and metallothionein levels in the adult rat.

Adult rats fed daily rations of laboratory chow laced with cobalt chloride were tested for operant (schedule-controlled) responding and conditioned suppression (CER). Animals exposed to 20 mg/kg Co, but not animals exposed to 5 mg/kg Co, lever pressed at a significantly slower rate than nontreated control subjects over the last 8 sessions of a 35 session operant training phase (1 session/day). Control and treatment subjects did not show significantly different CER performances. Nor were significant differences found on a test of mixed VI-2, DRO responding where subjects were required to lever press for reward during the first 15 min component and not lever press during the last 15 min component of the schedule. Testicular atrophy was evident among subjects exposed to 20 mg/kg Co. Atomic absorption spectrophotometric analyses revealed a dose-response effect regarding tissue accumulations of Co in blood, bone, brain, hair, small intestine, kidney, liver, and testes. Contrary to the biochemical pattern shown by some other heavy metals, prolonged Co exposure did not induce significant increases in metallothionein concentrations in the liver, kidney, or small intestine.

Animals↗

PubMedDate not supplied

The effects of chronic cadmium exposure on schedule controlled responding and conditioned suppression in the adult rat.

Adult rats fed daily rations of laboratory chow with added CdCl2 were tested for schedule controlled responding and conditioned suppression (conditioned emotional response-CER). Determinations of tissue Cd, levels of metallothionein, and the ratio of Cd in the tissue to the Cd-binding capacity of metallothionein also were made. Animals were exposed daily to either 5 mg/kg Cd (Group Cd-5), 1 mg/kg Cd (Group Cd-1), or no Cd (Group Control). An initial phase of training on a variable interval 2 min (VI-2) food reinforcement schedule lasting 40 sessions (1 session/day) was followed by CER training and then an interpolated period (100 days) of continued exposure but with no training. Schedule retraining was introduced for 21 sessions (1 session/day). The results showed no group differences during original schedule training. On the CER test, Group Cd-1 was found to exhibit less suppression (defined in terms of lever press rates) than controls to preaversive stimuli. Group Cd-5 showed significantly greater suppression to the primary aversive stimulus (shock) than the other two groups. Both treatment groups showed significantly lower lever press rates than controls on the schedule retraining task. These behavioral disturbances occurred commensurate with increases in non-metallothionein bound Cd in the liver, kidney, and small intestine.

Animals↗