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Biomedical subjects

P Emerson

Publications and source records attributed to P Emerson.

7 recordsLinked to original sources
PubMed1992

A peptidergic circuit for reproductive behavior.

A projection from the medial amygdaloid nucleus to the hippocampus and septum probably uses vasopressin as a transmitter. The nucleus synthesizes vasopressin and activation of the nucleus has a hippocampal effect that is completely blocked by a vasopressin antagonist. The afferent and efferent projections of this peptidergic nucleus suggest a possible role for the system in sexual behavior. Stimulation of the nucleus inhibits the output of the hippocampus in both genders and reorganizes behavior for a period of 15-20 min. In males, the effect of peptidergic activation is to produce a behavior that resembles the post-ejaculatory interval in coitus. This state is characterized by an EEG that resembles slow-wave sleep and by ultrasonic vocalizations at a characteristic frequency of 22 kHz. Castration in either gender causes depletion of the peptide from the target fields and eliminates the peptidergic signal in the hippocampus after about 15 weeks. The effects of castration in males can be reversed by testosterone replacement. The fluctuation of estrogen levels in rat plasma during the estrus cycle happens too quickly to impact the peptidergic system, and thus there is no significant change in the strength of the peptidergic signal among the proestrus, estrus, metestrus and diestrus stages. This fact permits study of the physiology of the system without concern for stage of estrus but does not permit conclusions regarding its function in females.

Amygdala↗
PubMed1989

A simplified method for autoregulation of blood flow in the extracorporeal membrane oxygenation circuit.

The ability of autoregulate blood flow in the extracorporeal membrane oxygenation (ECMO) circuit is critical to prevent cavitation and air embolism. Conventional circuits have used a spring-loaded mechanical switching device that interrupts the flow of power to the roller head when falling venous return collapses the venous bladder. This device has been less than desirable due to being poorly adjustable, subject to sporadic flow in periods of hypovolemia, and not commercially available. An improved alternative is reported using a commercially available pressure monitor and computerized switching device, which, when attached to the venous reservoir or bladder, has the ability to autoregulate blood flow in the ECMO circuit by smoothly regulating the roller head velocity. Experience with this system in the laboratory employing a swine model, and in 35 infants, is reported without device-related complications.

Equipment Design↗
PubMed1977

Timing of intraventricular haemorrhage.

The detection of the onset of intraventricular haemorrhage (IVH) during life is a necessary preliminary to understanding the cause of this condition. In 10 infants of very low birthweight treated with serial transfusions of adult blood the proportions of transfused cells circulating after each transfusion were compared with the proportion of transfused cells found in the intraventricular clot at necropsy. This allowed the timing of IVH to be restricted retrospectively to the period between consecutive blood transfusions. In addition, the proportional changes of transfused cells produced by infusion of a known red cell mass allow changes in the babies' original red cell mass to be followed during life. A fall in this value occurred in 8 infants dying with IVH and was taken to indicate haemorrhage. Comparison of the two methods in 9 infants suggested that, while in some cases intraventricular bleeding occurs rapidly, in others it takes place over a period of time. The interval between birth and the onset of haemorrhage was directly proportional to the gestational age of the infant.

Blood Transfusion↗
PubMed1977

Assessment of the agglutination test for tuberculosis.

A new whole cell agglutination test for active tuberculosis, for which encouraging results have recently been reported, has been carried out on the serum of 112 subjects. The results have been disappointing; the test had no predictive value in the diagnosis of active tuberculosis.

Agglutination Tests↗