Opiates have been shown to affect prolactin secretion directly at the pituitary level. However, opiate binding sites have not been characterized on anterior pituitary tissue. In the present work we show that a soluble factor present in anterior pituitary membrane preparation inhibit opiate binding on striatal membranes. The high concentrations of B-endorphin like immunoreactivity recovered from the supernatant of pituitary membrane preparations seem to account for this effect on striatal binding and to be responsible for a partial masking of pituitary opiate receptors. We thus attempted to improve membrane fractionation procedure in order to decrease B-endorphin contamination and thus to increase binding of opiate ligands on pituitary membranes. 3-H Etorphine binds to pituitary membranes with a constant of association (kon) of 20.8 10(6) M-1 min-1 and a constant of dissociation (hoff) of 33 min-1. Saturation experiments with 3-H Etorphine and 3-H ethylketocyclazocine indicate the presence of a single population of specific binding sites (KD) value of 12.2 +/- 3.9 nM a maximal binding capacity of 55.9 +/- 10.7 fm/mg protein for 3-H Etorphine binding). These results demonstrate the presence of opiate binding sites in the anterior pituitary. However the difficulty of the membrane preparation and the low density of binding sites did not allow a complete pharmacological characterization of these sites.

Animals↗

PubMedDate not supplied

Effects of age on short-term memory for time in rats.

Working memory (WM) for event duration was investigated in four different age groups of rats (6, 12, 18, and 24 months), using a delayed, symbolic-matching-to-sample procedure. In an initial experiment, all age groups responded as though a long sample duration were a short one when retention intervals (RI) were applied. This effect is called the choose-short effect. In a second experiment, in order to test whether, in compliance with the subjective-shortening model, there would be a "shortening" of the sample duration according to the length of the RI, the psychophysical function relating the probability of choosing the long comparison stimulus to sample duration and the point of subjective equality (PSE) were determined across successive RIs in two age groups (6 and 18 months). A significant shift of the psychophysical function towards a longer duration and a significant increase of the PSE appeared as a function of the RI in 6-month-old, but not in 18-month-old rats. These results support the idea that the choose-short effect is due to a shortening of the event duration in the WM in young animals, whereas there is no evidence that the sample forgetting occurred on a time dimension in older rats.

Aging↗

PubMedDate not supplied

Proportional assist ventilation may improve exercise performance in severe chronic obstructive pulmonary disease.

PURPOSE: Exercise tolerance is impaired in chronic obstructive pulmonary disease (COPD), in part because of a reduction in ventilatory capacity and excessive dyspnea experienced. The authors reasoned that proportional assist ventilation (PAV), a ventilator mode in which the level of support varies proportionately with patient effort, could be used during exercise to assist ventilation. The purpose of this study was to evaluate the efficacy of PAV to improve exercise endurance and related physiologic parameters in COPD. METHODS: In 8 patients (age = 62.8 years mean, +/- 6.9 standard deviation) with severe COPD (forced expiratory volume in 1 second = 0.70 +/- 0.21 L) flow, volume, dyspnea, leg fatigue, arterial blood gases, and gas exchange were measured during constant workrate exercise (37 +/- 18 watts; i.e., 80% previously determined maximum oxygen consumption). Crossover exercise trials were performed in random order: while spontaneously breathing through the experimental circuit without assistance (control trial) and with PAV (using 9.8 +/- 2.1 cm H2O/L and 3.3 +/- 1.0 cm H2O/L/sec of volume assist and flow assist, respectively). RESULTS: The application of PAV during exercise was well tolerated by each subject. Compared with the control measurement at equivalent time during exercise, PAV improved breathing pattern and arterial blood gases while dyspnea was reduced. Consequently, there was a significant increase in exercise duration with PAV (323 +/- 245 seconds during the control trial compared with 507 +/- 334 seconds with PAV, P = 0.02). CONCLUSIONS: Proportional assist ventilation can improve performance during constant workrate exercise in severe COPD.

Carbon Dioxide↗

PubMedDate not supplied

[Bronchocentric granulomatosis (author's transl)].

A case report and a review of this recently described entity are presented. A feature of interest in our case is the presence of Aspergillus fumigatus at the pulmonary needle biopsy as well as in the surgical specimen. This finding is described for the first time in a non asthmatic patient.

Aspergillus fumigatus↗

PubMedDate not supplied

[Bronchocentric granulomatosis (author's transl)].

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Bronchial Diseases↗