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Biomedical subjects

L J Hammond

Publications and source records attributed to L J Hammond.

31 records · Page 2Linked to original sources
PubMed1982

The involvement of the pentose shunt in thyroid metabolism after stimulation with TSH or with immunoglobulins from patients with thyroid disease. II. The reoxidation of NADPH and stimulation of hormone synthesis.

Reducing equivalents derived from the tissue re-oxidation of NADPH (NADPH-diaphorase) have been implicated in the peroxidation that is involved in the organification of iodine in the production of thyroid hormones. Immunoglobulin (Ig) fractions from patients with thyroid diseases and from normal controls, in a standard dose of 125 micrograms/ml and 0.3 microunits/ml thyrotrophin (TSH) were incubated with segments of guinea-pig thyroid gland maintained in vitro. A quantitative cytochemical study was made on how these fractions influenced the enzyme activity. A good correlation was found between the ability of such Ig fractions to stimulate the NADPH-diaphorase activity and (1) the degree of hyperthyroidism in the patients and (2) the amount of T3 secreted by the thyroid segments in vitro.

Animals↗
PubMed1980

The effect of contingency upon the appetitive conditioning of free-operant behavior.

The problem of maintaining independence between response rates and reinforcement probabilities when determining the effect of varying the response-reinforcement contingency upon free-operant behavior was solved by programming local reinforcement probabilities for response and no response on a second-by-second basis. Fifty-seven rats were trained to lever-press on schedules of water reinforcement involving different values of contingency. All rats were first trained on a high positive contingency and then shifted to less positive, zero, or negative contingencies. Under these conditions, rate of lever-pressing declined appropriately when the contingency between response and reinforcement decreased or was made negative. The decline in rate produced by a zero contingency cannot be attributed to extinction, since the probability of reinforcement given the occurrence of a response was the same as for the positive contingency from which the shift to zero was made. That is, there was no change in the opportunity for response-reinforcement contiguity. It was concluded that the technique of programming local reinforcement probabilities offers promise for more critical examinations of the effects of contingency upon free-operant behavior.

Journal Article↗
PubMed1970

Forgetting and conditioned suppression: role of a temporal discrimination.

Several experiments have found complete retention of conditioned suppression when overall suppression to the signal for shock was measured. The present experiment examined retention of conditioned suppression but did so with a paradigm that produced temporal discrimination of shock occurrence. Nine rats were exposed to a flashing light signal of 5-min duration that always terminated with a shock. After several months, a temporal discrimination was well established, as shown by maximum suppression toward the end of the signal period. After remaining in the home cage for 25 days, the rats were again subjected to the conditioning procedure. The overall level of suppression remained the same but the temporal discrimination was not observed.

Animals↗
PubMedDate not supplied

Cystic fibrosis, intravenous antibiotics, and home therapy.

The survival rate of patients with cystic fibrosis has improved considerably in the last 20 years. Although not all of the factors accounting for this change are understood, aggressive nutritional management and treatment of pulmonary exacerbations certainly play a role. Home intravenous (IV) antibiotic delivery for pulmonary exacerbation has proved to be as effective as hospital treatment and offers significant advantages to the patient and family. This article examines the microbiology of pulmonary infections in patients with cystic fibrosis, as well as antimicrobial therapy, methods of IV administration, home IV therapy, and the nurse practitioner's role in this home program in the future.

Anti-Bacterial Agents↗
PubMedDate not supplied

The Port-A-Cath and Per-Q-Cath.

Venous access in acute and chronically ill patients can become problematic when attempting to maintain a reliable system. The need for safe and dependable intravascular systems has become quite evident. This article examines the Port-A-Cath (Pharmacia, Inc., St. Paul, MN) and the Per-Q-Cath (Gesco International, Inc., San Antonio, TX). These systems are preferred by several patient populations who require frequent or prolonged intravenous therapy.

Catheterization, Central Venous↗
PubMedDate not supplied

The effects of ethanol on a measure of conditioned fear in mice.

The effects of ethanol on conditioned freezing, a species-specific defensive behavior used as an assay of fear, was examined in mice. In Experiment 1, ethanol, 1.2 g/kg, significantly increased freezing compared to a saline control when the mice were reexposed to a context in which they were previously shocked. Experiment 2, which administered ethanol or saline to no-shock control animals, demonstrated that the potentiated freezing produced by ethanol in Experiment 1 was specific to the interaction of ethanol and the stress response. These results suggest that both the qualitative and quantitative dimensions of the environmental stressor, as well as the dose of ethanol used, may be critical for determining ethanol's effect on a stress response.

Animals↗