Visual performance in the rhesus monkey after exposure to blue light.

Rhesus monkeys trained to perform a visual task (Landolt ring discrimination) were exposed for 1000 sec to known amounts of 441 nm light by means of a 2500 W xenon lamp with narrow bandpass filter. Radiant exposures to the macula of 30 J/cm² did not impair vision, but 60 J/cm² produced a transient loss of 20/20 vision which lasted from 20 to 30 days. A radiant exposure of 90 J/cm² produced a permanent loss of 20/20 vision. These results, in addition to explaining solar retinitis and eclipse blindness, correlate well with the retinal photopathology of the short wavelength photochemical lesion.     

A novel enzyme-linked immunosorbent assay (ELISA) for the detection of beryllium antibodies

A novel immunological method has been developed for detecting antibodies (IgG molecules) specific to beryllium, a light metal used in industry and capable of causing chronic beryllium disease. Beryllium metal was vacuum deposited onto commercially available immunological microsticks, which were then exposed to test plasma containing the putative antibodies. Antigen-antibody complexes were located using a biotin-avidin amplification method. One employee diagnosed with chronic beryllium disease and one diagnosed as "sensitized" (lymphocyte transformation positive) exhibited antibody titers graphically and statistically different and higher than a pooled baseline control population. Plasma from these two employees (former beryllium workers) was used in four different approaches to validate the presence of beryllium antibodies. The assay proved to be reproducible.     

Evidence that Dopaminergic Neurons are not Involved in the Negative Feedback Effect of Testosterone on Luteinizing Hormone in Rams in the Non-Breeding Season

In this study we tested the hypothesis that the negative feedback effects by testosterone on the secretion of luteinizing hormone (LH) in rams involves dopaminergic afferents to gonadotrophin-releasing hormone neurons operating via D(2) receptors in the non-breeding season. In the first experiment, three groups (n = 5) of rams were treated with an intravenous injection of vehicle or 10 or 20 mg of the dopaminergic D(2) antagonist pimozide and jugular venous samples were collected every 10 min for 3 h before and 3 h following treatment. The plasma was assayed for LH. Three groups of ewes (n = 4 to 5) were similarly treated. There were no significant effects of treatment of the rams with pimozide on the plasma concentrations of LH or LH pulse frequency or pulse amplitude and the response of individual rams in each group was inconsistent. In contrast, treatment of the ewes with 20 mg pimozide significantly (P<0.001) increased the mean (± SEM) plasma LH concentrations (pretreatment 0.37 ± 0.04; post-treatment 2.42±0.25 ng/ml) and decreased (P<0.001) the LH inter-pulse interval (pretreatment 180.0; post-treatment 88.0±11.1 min); the 10 mg dose of pimozide did not affect these parameters. In the second experiment, two groups of rams (n = 5) and ewes (n = 7) were treated with an intravenous injection of vehicle or 0.33 mg pimozide/kg liveweight and jugular venous samples were collected every 10 min for 2 h before and 6 h following treatment. As in the first experiment, the mean (± SEM) concentrations of plasma LH were not affected by treatment with pimozide in the rams (pretreatment 0.18 ± 0.25; post-treatment 0.43 ± 0.14 ng/ml) but were significantly (P<0.05) increased in the ewes (pretreatment 1.12±0.22; post-treatment 1.93 ± 0.23 ng/ml). In the third experiment, four adult rams were castrated and 3 weeks later each animal had two cannulae inserted to allow injection into the lateral cerebral ventricles. Vehicle or 100 μg pimozide was injected intracerebroventricularly and blood samples were collected as in the other experiments. A Latin Square design was used so that each animal received each treatment (n = 4). This procedure was repeated after the animals had been injected (intramuscularly) with 16 mg testosterone propionate twice daily for at least 7 days. Treatment with testosterone propionate significantly decreased (P < 0.001) the plasma concentrations of LH (pre-treatment 7.71±0.27; post-treatment 0.75 ± 0.27 ng/ml; mean ± SEM) and follicle-stimulating hormone (pre-treatment 79.61±8.47; post-treatment 42.53 ± 6.08 ng/ml; mean ± SEM) and increased the mean (± SEM) LH inter-pulse interval (53.14 ± 3.58 min pre-treatment and 292.5 ± 32.94 min post-treatment) but had no effect on the amplitude of LH pulses (pre-treatment 3.61 ± 0.36; post-treatment 1.86±1.76 ng; mean ± SEM). Pimozide had no effect on the plasma concentrations of gonadotrophins. These results suggest that, in the ram, dopaminergic neurons do not influence the gonadotrophin-releasing hormone neurons via D(2) receptors in the non-breeding season and are not involved in the negative feedback effect of testosterone on the secretion of gonadotrophins. Conversely, our data suggest that such a mechanism is integral to the negative feedback effects of oestradiol on LH in anoestrous ewes. Finally, it also appears that the steroid-independent suppression of the secretion of gonadotrophins during the non-breeding season in rams is not mediated via D(2) receptors.     

Pulmonary pseudocysts in newborn infants with respiratory distress syndrome.

Twelve neonates who developed intrathoracic cystlike structures ("pseudocysts") are described. All infants had clinical and radiographic respiratory distress syndrome and all were treated with assisted ventilation. Pulmonary interstitial emphysema preceded the development of the pseudocysts in all cases. The pseudocysts appeared between 0 and 6 days of life (average, 2.4 days), and radiographically documented disappearance occurred in 10 patients at 3--18 days old (average, 7.0 days). Two patients had persisting pseudocysts at 8 and 25 days of age, and no subsequent radiographs. In no case did these structures persist symptomatically or require surgical intervention such as has been described with patients in other series. In two cases, abrupt disappearance of the pseudocysts was accompanied by increased extraalveolar gas in other locations. Eight patients developed radiographic bronchopulmonary dysplasia, which was severe in two of the cases.     

The urological status of 86 females following spinal cord injury

A review of the urological problems in 86 female spinal cord injury patients is presented. There were no urological or renal deaths. Three urinary diversions were performed. Fifty-five patients are catheter-free and 28 are managed with permanent catheter drainage. The problems of "bladder training" are presented.