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Biomedical subjects

L Chapman

Publications and source records attributed to L Chapman.

At least 55 records · Page 3Linked to original sources
PubMed1991

Searching: expectant fathers' experiences during labor and birth.

When expectant fathers are present and view labor and birth as a couple experience, they are co-laboring in one of three roles: coach, teammate, or witness. Within these roles are various degrees and types of engagement. Men in the role of coach experience high degrees of physical and mental engagement. Teammates fluctuate between high and low degrees of physical and mental engagement, and witnesses remain at low degrees of engagement until the second stage of labor, when they experience high degrees of mental engagement. The expectant fathers' experience is influenced by the labor guides' activities of gatekeeping, leading, and informing. Men either maintain or redefine their role during labor and birth. Men who experience a sense of not belonging or who are uncomfortable with their role will redefine their role by using the strategy of searching for place. Searching for place involves the steps of identifying an alternative role, engaging in the new role, testing the role, and evaluating the effectiveness of the alternative role. Men who experience a sense of belonging in their new role will maintain this role. May posed the question, "Is it time to fire the coach?" This theory, which requires further testing and validation, does address May's question. Perhaps it is not time to fire the coach, as May indicated, but it is time to provide couples with options in the role expectant fathers play during labor and birth. This theory can guide nurses in relatively risk-free interventions for the expectant father. Nurses can assist expectant fathers in finding a place in labor and birth that will enhance a mutually satisfying birthing experience.

Adult↗
PubMed1988

Profound muscle weakness and hypokalemia due to clay ingestion.

We have presented the case of a 43-year-old woman with severe myositis due to clay ingestion and hypokalemia. EMG studies revealed a pattern consistent with myositis, and muscle biopsy showed a nonspecific diffuse myositis. The clay was shown to act as a potassium binder. With potassium replacement and discontinuance of clay ingestion, the symptoms and signs abated and laboratory values returned to normal.

Adult↗
PubMed1987

Hemophilus influenzae meningitis in the rat: behavioral, electrophysiological, and biochemical consequences.

Hemophilus influenzae is the most common cause of bacterial meningitis in children, and a high percentage of survivors are at risk for long-term sequelae. To explore the mechanisms responsible for these sequelae, a neonatal rat model was used to define the behavioral, electrophysiological, and biochemical changes following meningitis. Three days after inoculation of 6-day-old rats with a minimum of 1 X 10(7) colony-forming units of a virulent Hemophilus influenzae, type b, cerebrospinal fluid and blood were cultured to confirm the presence of meningitis and bacteremia, respectively. At this time, forebrain norepinephrine and dopamine levels were significantly elevated in meningitic rats when standardized on a wet-weight basis. No changes in brain serotonin or heart norepinephrine levels could be found in the 9-day-old rats. No residual changes were found in steady-state concentrations of norepinephrine or dopamine in surviving adult rats. However, survivors that had had meningitis as neonates showed significant impairment in active and passive avoidance learning tasks and demonstrated a significantly higher level of activity during a habituation period in circular photocell activity cages. No change in the flinch-jump threshold was detected. Brainstem auditory evoked potentials showed delays of various waves in 3 of 10 Hemophilus influenzae type b-treated adult rats tested. These rats also exhibited markedly augmented locomotory responses to d-amphetamine (1 mg/kg), suggesting a long-lasting perturbation of central monoamine neuronal transmission.

Age Factors↗
PubMed1986

Synergistic neurotoxicity of carbon tetrachloride/carbon disulfide (80/20 fumigants) and other pesticides in grain storage workers.

Neurophysiologic, neurobehavioral, and neuropsychologic profiles in 17 grain storage workers, 1 grain inspector, and 4 malting laboratory workers are described. The effects of CS2 toxicity as seen in viscose rayon workers as well as in experimental animals is remarkably similar to the clinical profile of our grain storage workers. CS2 use explains the dysfunction of peripheral axons, auditory nerve, the optic nerve, and the extrapyramidal system, as well as altered behavior and cognition changes. The signs and symptoms in these workers seem to be dose-related and we note that workers separated out from the areas where fumigation took place reported improvement not seen by fellow workers who continued the fumigant treatment routine. Likewise, malting laboratory workers exposed only to the grain dust from 3 to 7 years showed only minimal symptoms. Though a number of mechanism have been suggested for the alteration of neuropsychological function, the chelating ability of DDC derived from CS2 and its ability to markedly increase copper and zinc within the central nervous system suggests a mechanism of toxicity analogous to copper intoxication as in Wilson's Disease and may explain the production of extrapyramidal symptoms in these patients. Chelation of copper might prove therapeutic in CS2 poisoning. It is obvious that both basic and clinical research will be necessary to sort out the questions raised. We applaud the EPA's decision to ban the use of 80/20 fumigants and also methyl bromide, and trust that similar toxic substances be carefully studied before their selection for replacing these previous toxic agents. We further decry the technique of re-introducing grain dust into the food chain rather than destroying it, since the dust contains very high residues of fumigant material. We speculate on the possible role of CS2 and other pesticides in the food chain and the incidence of Parkinsonian symptoms in these patients and the general public.

Adult↗
PubMed1983

Consecutive exotropia following surgery.

We studied 250 patients with consecutive exotropia. The interval between the surgical procedure and the onset of the consecutive exotropia may take many years. Consecutive exotropia occurred with all types of corrective esotropia surgery that we studied. Amblyopia and medial rectus limitation postoperatively seemed to be common factors associated with consecutive exotropia.

Amblyopia↗
PubMed1980

d-Amphetamine, operant history, and variable-interval performance.

The effects of d-amphetamine on the bar-pressing of rats maintained under a variable-interval schedule of water reinforcement were examined as a function of the operant history of the subjects. One group of rats initially received 51 sessions of exposure to a fixed-ratio 20 schedule, while a second group received equivalent exposure to an interresponse-time-greater-than-12-sec schedule. Mean group response rate when stable was over ten times as high under the fixed-ratio schedule as under the interresponse-time-greater-than-12-sec schedule. Response rates of the two groups largely converged across 47 sessions of exposure to a variable-interval 60-second schedule, at which time response rates for both groups appeared stable. Acute administration of d-amphetamine sulfate similary affected mean response rates of both groups: A 0.25 mg/kg dose did not obviously affect rate, while doses of 0.5, 1.0, and 2.0 mg/kg produced dose-dependent rate decreases. These results indicate that the efficacy of operant history as a determinant of drug effects may be limited to circumstances where current contingencies do not exercise powerful and direct control over behavior.

Animals↗
PubMed1980

Polydipsia induced by intermittent delivery of salted liquid foods.

Food-deprived rats given constant access to water were exposed to fixed-time presentations of soybean milk and diluted sweetened condensed cows' milk. In some conditions these liquid foods were adulterated with varying amounts of sodium chloride. Under a fixed-time 30-sec schedule of food delivery, little water was consumed when the food was soybean milk alone, or soybean milk with sodium chloride added in concentrations of .9, 1.8, or 3.6%. However, schedule-induced polydipsia appeared when soybean milk adulterated with 7.2 or 14.4% sodium chloride was delivered under this schedule. When soybean milk containing 7.2% sodium chloride was presented under fixed-time 15-, 30-, 60-, 120-, and 240-sec schedules, schedule-induced drinking increased with the fixed-time value from 15 to 120 seconds, and decreased at 240 seconds. Like soybean milk, diluted sweetened condensed milk delivered under fixed-time schedules of 30, 60, and 120 seconds failed to evoke schedule-induced polydipsia, but did so when adulterated with 7.2% sodium chloride. Drinking induced by salted liquid foods resembled the polydipsia engendered by spaced dry-food presentations in several ways, including temporal relation to food delivery, persistence within and across sections, sensitivity to interfood interval, and magnitude relative to intake evoked by bulk-food presentation.

Animals↗
PubMed1976

Serum cystine aminopeptidase and the small-for-dates baby in hypertensive pregnancy.

Serum cystine aminopeptidase levels and gradients have been assessed retrospectively in hypertensive mothers delivering small-for-dates babies, compared with those delivering normal weight babies. The average accuracy of predicting the weight range of the infant (normal or small-for-dates) would have been about 82 per cent.

Aminopeptidases↗
PubMed1975

Serum cystine aminopeptidase and the normal weight baby in normotensive and hypertensive pregnancy.

The levels of serum cystine aminopeptidase have been studied serially in normotensive and hypertensive mothers who delivered healthy, normal weight-for-dates babies. A normal range, both for enzyme level and maximum and minimum rates of increase of the enzyme during gestation, was established for each group, those of the hypertensive patients exhibiting different characteristics from the curves in normotensive patients. It is suggested that such differences be considered when assessing pregnancies complicated by hypertension.

Aminopeptidases↗