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Biomedical subjects

R McBride

Publications and source records attributed to R McBride.

42 records · Page 3Linked to original sources
PubMedDate not supplied

Raphe neurons and barbiturate induced rhythmic activity in the subthalamic nucleus and ventral tegmental area.

A continuous rhythmic discharge in the subthalamic nucleus (STN), lateral habenular nucleus, and ventral tegmental area (VTA) is associated with tremor in cats lightly anesthetized with barbiturate. The pontine raphe nuclei centralis superior and inferior also show barbiturate dependent slow wave and unitary activity. Stimulation of the raphe region produces evoked potentials and synchronization of the oscillatory activity in STN and VTA. The latency of the evoked response is shortest in STN. Extensive raphe lesions abolish the rhythmic activity in STN and VTA, but lesions which do not completely destroy nuclei centralis superior and inferior are not effective. In single cell recordings 81% of 142 cells in the pontine raphe region and medial reticular formation are inhibited following VTA stimulation. Fifty-four percent of 129 cells in the same region were inhibited when tested with STN stimulation. Forty-seven raphe paramedian reticular formation cells showed convergence of inhibitory input from STN, VTA, and contralateral sciatic nerve (Group II and III fibers). Depletion of serotonin with rho-chlorophenylalanine did not affect the appearance of barbiturate rhythmic activity. It is concluded that the pontine raphe region is not essential for maintenance of the oscillatory activity in STN and VTA, and that the raphe region is on the output side of the system.

Animals↗
PubMedDate not supplied

Age and clinical immunity to infections with Chlamydia trachomatis.

BACKGROUND AND OBJECTIVES: The prevalence of chlamydial infection decreases with age possibly in part because of increasing immunity. GOAL OF THIS STUDY: To determine whether increased age is an independent predictor of decreased chlamydial infection and whether chlamydia-specific antibody titer and blastogenesis increase with age. STUDY DESIGN: Data from all patients cultured for Chlamydia trachomatis between January 1984 and August 1989 were examined and multiple logistic regression models were used to identify the independent predictors of culture positivity. Antichlamydial antibody titer and chlamydia-specific blastogenesis were examined for a subset of patients for correlation with age. RESULTS: Young age was found to be predictive of chlamydial infection independent of all factors examined in men and women. Antibody titers had no relation to age (n = 245) whereas the level of blastogenesis correlated only weakly with age (n = 155). CONCLUSIONS: Assays of systemic immunity do not reflect the protection from chlamydial infection associated with age.

Adolescent↗
PubMedDate not supplied

Prospective evaluation of factors associated with intraaortic balloon rupture.

The authors undertook a prospective analysis of all intraaortic balloon catheter (IAB) insertions at Hahnemann University Hospital during an 18 month period. Attention was directed to balloon rupture and factors associated with this complication. A total of 384 insertions were attempted in 363 patients: 19 patients (5.2%) experienced balloon rupture. The mean time to rupture was 2.1 +/- 3.3 days (range 0-15 days). All ruptured IAB catheters were removed percutaneously without subsequent complications. Ten balloons were subjected to leak testing and scanning electron microscopy. All but one rupture appeared to be the result of balloon abrasion against atherosclerotic plaque. The puncture site occurred at variable distances from the proximal end of the balloon at 9.4 +/- 8.3 cm. Comparison of patients with and without balloon rupture revealed several significant (p < 0.04) differences by univariate analysis (Table 1). No procedure related variables (IAB catheter size 9 versus 11 Fr, sheathless insertion, duration of counterpulsation) were associated with rupture. Stepwise logistic regression analysis revealed body surface area as the only independent predictor of balloon rupture (p = 0.007). Intraaortic balloon rupture with 40 cc balloons, is directly related to the size of the patient. Evaluation of smaller balloons in patients with body surface area < or = 1.8 m2 appears warranted to minimize IAB rupture.

Aged↗