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Biomedical subjects

G Hanson

Publications and source records attributed to G Hanson.

114 records · Page 7Linked to original sources
PubMedDate not supplied

Physiological chemoreceptor stimulation decreases enkephalin and substance P in the carotid body.

Neuroactive peptides, including the enkephalins (Met- and Leu-enkephalin; ME, LE) and substance P (SP) are known to be present in the mammalian carotid body, an arterial chemoreceptor organ sensitive to the O2, CO2 and pH levels in blood. The principal parenchymal (type I) cells of the organ, which receive sensory innervation from the carotid sinus nerve (CSN), have been shown to contain both ME and SP; SP is also present in CSN afferent fibers. In the present study, rabbits were exposed in a chamber to a physiological chemoreceptor stimulus (5% O2 in N2) for one hour, then anesthetized during surgical removal of both carotid bodies for later RIA measurement of ME and SP levels in the tissue; control animals were exposed to air in the chamber, but otherwise treated as the hypoxic animals. Both ME and SP levels were significantly reduced (approximately 40%) in the carotid bodies from hypoxic rabbits, compared to their normoxic controls. The results suggest that these neuroactive peptides are released from carotid body elements during physiological stimulation, and consequently may play a role in the transduction of chemosensory information between the type I cells and their apposed afferent terminals.

Anaerobiosis↗
PubMedDate not supplied

Disposition of a new antiinfective agent 1,3-di(4-imidazolino-2-methoxyphenoxy)propane in male rats.

The disposition of 1,3-di[4-imidazolino-2-methoxyphenoxy]propane (DMP) is described in male rats following a single 2.5 mg/kg intravenous or 10 mg/kg oral administration of DMP lactate in an aqueous (5% dextrose) solution. Following the intravenous administration, plasma concentrations of DMP declined in an apparent biexponential manner and were nonmeasurable after 24 hr. The mean terminal plasma elimination half-life was 14.9 hr. A volume of distribution of 18.7 liters/kg and a body clearance of 14.5 ml/min/kg were estimated. After oral administration, mean plasma concentrations of DMP reached a maximum of 39.6 ng/ml at 15 min and were nonmeasurable after 4 hr. The areas under the curve (AUC)0-24 of DMP was 2276 ng.hr/ml following the intravenous dose. The AUC0-4 was 68 ng.hr/ml following the oral dose. The AUC0-4 was 68 ng.hr/ml following the oral dose. Based on a comparison of AUC0-4, the oral bioavailability was 0.9%. A mean of 41.7 and 0.4% of the dose was excreted in urine as DMP following intravenous and oral administration, respectively. The tissue distribution and mass balance of total 14C were determined following a single 2.5 mg/kg intravenous administration of [14C]DMP.lactate. The concentrations of total 14C in all tissues were highest at 0.5 hr and declined with time thereafter. The highest concentration of 14C was in the kidneys, whereas the highest total amount was in the liver.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMedDate not supplied

Organising the MRCP exam--a guide for registrars.

Taking the MRCP exam as a candidate can be traumatic. For the registrar who has to organise one, the task may be just as daunting. Efficient coordination of candidates, patients and examiners and the provision of good clinical material in a suitable setting requires considerable organisation. This supplement to the guide issued by the College, based on our own experience, describes in more detail the preparation and management of the examination in the hope that it will ease our colleagues' tasks.

Clinical Competence↗
PubMedDate not supplied

The pharmacokinetics of 1,3-di(4-imidazolino-2-methoxyphenoxy) propane.lactate (DMP.lactate), a new agent against opportunistic infections, in male beagle dogs.

The pharmacokinetics and oral bioavailability of 1,3-di(4-imidazolino-2-methoxyphenoxy) propane.lactate (DMP) was determined in male dogs following iv and po administrations of DMP.lactate containing trace amounts of [14C]DMP.HCl. Following the iv administration of [14C]DMP.lactate (2.5 mg/kg), plasma concentrations of DMP declined in a biexponential manner and were measurable to 48 hr. The terminal elimination half-life was 37.7 hr. The mean AUC0-infinity of DMP was 1.58 micrograms.hr/ml. The volume of distribution was 89 liters/kg and the body clearance was 27 ml/min/kg. The disposition of total radioactivity was similar to that of DMP. Approximately 14% of the dose was eliminated in urine as DMP or total radioactivity. Renal clearance was 10% of the body clearance. Following the po administration of [14C]DMP.lactate (14 mg/kg) the mean Cmax of total radioactivity and DMP was 0.20 and 0.17 micrograms/ml, respectively. The respective mean AUC0-T was 0.37 and 0.21 micrograms.hr/ml. The mean oral bioavailability based on DMP plasma concentrations was 2.4%. The mean Cmax of DMP following a 100 mg/kg po dose of DMP.lactate was 14 micrograms/ml and the AUC0-T was 1.87 micrograms.ml/hr; the bioavailability was 3.2%. Approximately 1% of the orally administered dose was eliminated in urine as DMP.

Administration, Oral↗