Ultradian, circadian and seasonal rhythms in cortisol secretion and adrenal responsiveness to ACTH and yarding in unrestrained red deer (Cervus elaphus) stags.

Seasonal changes in the activity and responsiveness of the adrenal gland in red deer (Cervus elaphus) stags were quantified by measuring 24 h endogenous cortisol secretory profiles and plasma cortisol responses to either administration of exogenous ACTH or a standardised stressor during November (period of velvet growth), February (pre-rut), April (mid-rut) and July (post-rut) (southern hemisphere) using a remote blood sampling device (DracPac). Ultradian rhythms in the concentration of plasma cortisol were observed resulting from the episodic secretion of cortisol from the adrenal cortex at a mean rate of 0.8 pulses/h. Circadian rhythms in plasma cortisol concentrations were also found in 11 out of the 20 complete 24 h profiles (mean amplitude, 3.8+/-1.4 ng/ml). Seasonal rhythms in mean 24 h plasma cortisol concentrations and cortisol pulse parameters were also observed. Mean 24 h plasma cortisol concentrations were higher in November (12.5+/-1.0 ng/ml) than in February (6.3+/-1.0 ng/ml), April (4.0+/-1.0 ng/ml) or July (4.2+/-1. 0 ng/ml). Cortisol pulse height, nadir and amplitude were all significantly higher in November than at other times of the year (P<0.01). Peak cortisol concentrations following infusion of ACTH(1-24) (0.04 IU kg(-1)) were higher (P<0.05) in November (55.8+/-2.7 ng/ml) and lower (P<0.001) in April (33.7+/-1.8 ng/ml) than those in February and July (48.7+/-2.0 ng/ml and 45.4+/-2.0 ng/ml respectively). The area under the cortisol response curve was significantly smaller (P<0.05) in April (266.6+/-15.3 ng/ml/190 min) than at other times of the year (February, 366.1+/-15.3 ng/ml/190 min; July, 340.7+/-15.3 ng/ml/190 min and November, 387.8+/-21.2 ng/ml/190 min). These data demonstrate that the adrenal gland of the red deer stag exhibits ultradian, circadian and seasonal rhythms in activity, and that its responsiveness to ACTH varies with season. November, a period of reproductive quiescence in the southern hemisphere, with new antler growth and rapid weight gain, is associated with higher mean plasma cortisol concentrations and a greater responsiveness to exogenous ACTH. In contrast, the breeding season is associated with lower adrenal activity and responsiveness.

Sensitivity of routine blood bank methods for the detection of anti-D as determined during proficiency testing.

A proficiency testing program in immunohematology, involving over 240 laboratories, was used to assess the detection of anti-D in six concentrations ranging from 11 to 8,500 ng/mL. Using the indirect antiglobulin test, more than 98% of laboratories reporting detected anti-D at all concentrations. Enzyme and albumin antiglobulin methods as routinely practiced did not clearly increase sensitivity, and the direct agglutination methods used were much less sensitive than indirect antiglobulin methods. If proficiency testing truly reflects performance in practice in Ontario, Canada, the sensitivity of manual indirect antiglobulin methods in routine use for the detection of anti-D appears to meet reasonable expectations of these technics.

The bacteriological diagnosis of pyogenic meningitis from cerebrospinal fluid dried on filter paper.

Cerebrospinal fluid from patients with pyogenic meningitis in two rural hospitals in Nigeria was dried on filter paper and sent by post for analysis in a reference laboratory. Microbial antigens were detected by counter-current immunoelectrophoresis in 78 of the 142 specimens (55%). This method of detecting antigens deserves further application for epidemiological and diagnostic work in developing countries.