Genomewide clonal analysis of lethal mutations in the Drosophila melanogaster eye: comparison of the X chromosome and autosomes

Using a large consortium of undergraduate students in an organized program at the University of California, Los Angeles (UCLA), we have undertaken a functional genomic screen in the Drosophila eye. In addition to the educational value of discovery-based learning, this article presents the first comprehensive genomewide analysis of essential genes involved in eye development. The data reveal the surprising result that the X chromosome has almost twice the frequency of essential genes involved in eye development as that found on the autosomes.

Nitric oxide generation from streptozotocin

Streptozotocin (STZ), a diabetogenic agent, is thought to damage pancreatic beta-cells by activating immune mechanisms and by alkylating DNA. In the present study, we demonstrated that STZ can produce nitric oxide (NO), a bioregulatory and cytotoxic molecule. When STZ was dissolved in a sodium phosphate buffer (50 mM, pH 7.4) and irradiated with a 22 W circular fluorescent light, nitrite and nitrate, stable oxidation products of NO, were produced. The wavelengths of light most responsible for the photo-decomposition were 300-310 nm and 410-420 nm. When a mixture of reduced hemoglobin and STZ was irradiated with UV light (280-320 nm), hemoglobin underwent characteristic NO-dependent spectral changes. STZ relaxed deendothelialized aortic strips only in the presence of light. STZ/light-dependent relaxation was attenuated by reduced hemoglobin. These results indicated photo-induced NO production from STZ. NO generation depended on the concentration of STZ, the duration of irradiation, and the distance between sample and light source. In acidic conditions, NO production from STZ was spontaneous even in the dark. Light-independent NO generation was augmented by increasing acidity, and markedly diminished in a D2O-based buffer, indicating the involvement of protons in the mechanism of STZ decomposition in acid. These results imply the usefulness of STZ as an NO-generating reagent, and indicate that direct NO-generation may be a mechanism of STZ toxicity in diabetogenesis.

The sympathetic nervous system and the renin-angiotensin system in borderline hypertension

1. Plasma catecholamine levels as well as plasma renin activity and plasma renin concentration were compared in normotensive volunteers and in subjects with borderline hypertension. All subjects were studied at rest and during bicycle ergometry. 2. The two groups of volunteer subjects did not differ in the plasma concentrations of noradrenaline and adrenaline, both at rest and during physical activity. The same was true for plasma renin activity and plasma renin concentration. Furthermore, urinary excretion of noradrenaline, adrenaline and 4-hydroxy-3-methoxymandelic acid was similar in both groups. 3. The results do not support the assumption that there is increased sympathetic activity in subjects with borderline hypertension.

Antihypertensive therapy in elderly patients. Pilot trial of the European Working Party on High Blood Pressure in the Elderly

A study protocol for a double-blind randomised control trial of hypotensive treatment in elderly hypertensive patients has been tested in a number of pilot centres throughout Europe. It was shown that this study is possible from the logistic point of view. In these elderly patients, hydrochlorothiazide + triamterene treatment with or without methyldopa, maintained a significant hypotensive effect in the absence of major electrolyte disturbances. The initiation of hypotensive therapy did not provoke an excess of cardiovascular complications. The influence of hypotensive therapy on the general well-being and on the morbidity and the mortality of elderly patients with high blood pressure, is thereby being assessed. The study will continue for 5 years and other centres are invited to join.