Decreased energy requirement of toad retina during light adaptation as demonstrated by 31P nuclear magnetic resonance.

1. The effect of light and dark adaptation on the levels of phosphorus metabolites (nucleotide di- and triphosphates, phosphocreatine, pyridine nucleotide, inorganic phosphate, phosphodiesters, phosphomonoesters, and uridine diphosphate-glucose) in the toad (Bufo marinus) retina and retinal extracts was studied by 31P nuclear magnetic resonance (NMR) spectroscopy. 2. Spectra were acquired using an NMR probe specifically designed for superfusion and illumination of a single retina. Retinae were maintained at a steady state for up to 10 h in an electrolyte solution containing 10 mM Hepes buffer and bubbled with 98% O2-2% CO2, pH 7.8 at 20 degrees C. 3. The intracellular concentrations of the phosphorus metabolites were measured in total darkness or during prolonged exposure to light. The concentration of nucleoside triphosphates (NTP) in the dark-adapted retina was about 1.5 mM and that of phosphocreatine (PCr) was about 0.7 mM. 4. In saturating levels of light, 6.0 x 10(11) or 1.5 x 10(13) quanta s-1 cm-2 at 520 nm, the levels of PCr and phosphomonoesters rose, the levels of NTP and protons (pH) were maintained, and the levels of pyridine nucleotides and nucleotide diphosphates (NDP) fell. 5. A rise in the level of PCr in the presence of an unchanged level of NTP in the light-adapted retina indicates that the energy consumption of the retina is greater in the dark. 6. These results are in agreement with the results of oxygen consumption, glucose dependence, and electrophysiological studies which also indicate that the metabolic energy requirement of the retina decreases in light.

Pertussis toxin expression in Drosophila alters the visual response and blocks eating behaviour.

Pertussis toxin inactivates certain G-proteins by introducing an ADP-ribose group near the carboxyl-terminus of the alpha-subunit. The major pertussis toxin substrate in Drosophila tissues is Go alpha. We introduced a pertussis toxin gene under control of the hsp70 heat-shock promoter into the Drosophila genome. When heat-shocked, transformed flies produce active pertussis toxin which ADP-ribosylates endogenous Go alpha. Pertussis toxin is expressed in photoreceptors, in the lamina of the eye and in epithelial cells lining the gut. As expected from the absence of Go alpha in photoreceptors, pertussis toxin does not affect the photoreceptor component of the Drosophila visual response. However, it abolishes light on- and off-transients in the electroretinogram. These transients normally arise from the lamina, a tissue where Go alpha transcripts have been detected. Pertussis toxin expression also blocks embryonic development and shortens the lifetime of adult Drosophila. Following heat-shock, transformed adults are active, but they fail to take up nutrients because they stop eating. High energy metabolites are significantly depleted shortly after pertussis toxin expression is induced and the flies die within 48 h.

Biochemical evaluation of endometrial biopsies by magnetic resonance spectroscopy--preliminary data.

Biochemical study of tissue biopsy samples by magnetic resonance spectroscopy involves relatively small capital and running costs and could become a routine diagnostic or screening procedure if its utility were to be adequately demonstrated. We have demonstrated feasibility of evaluation of endometrial biopsy samples by magnetic resonance previous to histopathologic examination. Preliminary comparisons of magnetic resonance spectra with histopathologic evaluation indicates that in at least some instances, magnetic resonance may be the more sensitive indicator of disease.

Phosphorus-31 nuclear magnetic resonance spectroscopy of toad retina.

Phosphorus-31 nuclear magnetic resonance (31P-NMR) spectra were obtained from living toad retinae and toad retinal extracts at 4 degrees C. Several phosphorus metabolites--nucleoside di- and triphosphates (NTP), phosphocreatine, phosphodiesters, inorganic phosphate, and phosphomonoesters--were identified from the spectra of whole retinae. The intracellular pH was determined to be 7.27 +/- 0.06 at 4 degrees C and the intracellular MgNTP/NTP ratio was at least 0.77. These results are consistent with those reported by other techniques, and they show that 31P-NMR spectroscopy can be used for noninvasively and quantitatively studying the metabolism of living toad retinae, and for monitoring its changes over time.

A plan to prevent adolescent pregnancy and reduce infant mortality.

In Illinois, particularly in Chicago, the infant mortality rate is higher than that for the nation as a whole. Unless infant mortality in Illinois declines at a faster rate, the State will not meet the objective for reducing infant mortality specified by the Surgeon General of the Public Health Service. Low birth weight infants are at high risk of medical problems, if not death, and teenage mothers have an increased risk of bearing low birth weight infants. This paper presents a program aimed at the primary prevention of adolescent pregnancy. The three-component, interactive program--sex education, adolescent clinic services, and community support and involvement--is proposed for preventing adolescent pregnancy which, in turn, will decrease the rate of births of low birth weight infants and, consequently, the rate of infant mortality in target areas of Illinois. Medical and college students will be trained to teach the sex education course and to serve as counselors. A clinic will provide primary care, contraceptive education, and access to contraceptives. The clinic staff will be a resource for the community as well as for the adolescents. In the target areas, church and community members will sponsor health fairs and discussions of adolescent pregnancy at church and at parent-teacher association meetings. The overlapping activities of the instructors, clinic personnel, and church and community members will give continuity and consistency to the prevention message directed to the adolescents.

Regional lymph node involvement in tuberculoid leprosy.

A study of regional lymph nodes in 44 cases of proved tuberculoid leprosy (BT & TT) is presented. Out of 26 cases of tuberculoid polar (TT) leprosy, 76.92% showed presence of paracortical lymphocytes, 61.52% showed presence of granuloma and 11.54% showed presence of acid fast bacilli in lymph nodes. In the borderline tuberculoid (BT) group, 61.1% showed granuloma, 72.22% showed presence of paracortical infiltration by lymphocytes and 11.11% showed presence of A.F.B. in lymph nodes. Lesions of tuberculoid leprosy have been conclusively demonstrated in the low resistant tuberculoid (BT) leprosy and polar tuberculoid leprosy (TT). The presence of paracortical lymphocytes in large numbers in the lymph nodes could indicate high cell mediated immunity (CMI) and possibly a tuberculoid end of the spectrum. The skin lesions and lymph nodes had comparative histopathology.