Pathogenicity Resulting from Mutation at the b Locus of Ustilago maydis

This paper explores the genetic basis of the ability of the fungus, Ustilago maydis, to induce neoplastic galls in the corn plant (Zea mays). Pathogenic mutants of U. maydis were produced by ultraviolet irradiation of cultures of nonpathogenic diploids homozygous at the b locus. The mutants formed smaller neoplasms, produced fewer teliospores, and showed higher frequencies of meiotic failure and lower rates of basidiospore survival than did the wild-type fungus.     

Regression of Posterior Uveal Melanomas Following Cobalt-60 Plaque Radiotherapy

A method has been devised for evaluating the rate and extent of regression of the first 100 consecutive patients with a posterior uveal melanoma that we had managed by Cobalt-60 plaque radiotherapy at Wills Eye Hospital. It was found that the "average" posterior uveal melanoma in the series did not regress rapidly to a flat, depigmented scar but shrank slowly and persisted as a residual mass approximately 50% of the thickness of the original tumor at 54 months following Cobalt-60 plaque radiotherapy. We also found that the rate and extent of regression of the tumors in patients who subsequently developed metastatic melanoma were not appreciably different than the rate and extent of regression of the tumors in patients who remained well systemically. These observations indicate that the rate and extent of regression of posterior uveal melanomas following Cobalt-60 plaque radiotherapy are poor indicators of the prognosis of the affected patients for subsequent development of clinical metastatic disease.     

A case-control study of cervical cancer screening in north east Scotland

To estimate the relative risk of invasive cervical cancer in each succeeding year after a negative screening result the screening records of all women tested in the north east of Scotland were examined as the basis for a case-control study. The cases consisted of 115 women in whom invasive cervical cancer had been diagnosed in 1968-82 and who had appeared in the screening records at least once before diagnosis. For each patient five controls were selected from women of the same age who appeared in the screening records before the date of diagnosis in the patient. If the patient's cancer had been detected by screening the controls were chosen from women of the same age screened the same year. A comparison was made between cases and controls of the number of negative smears taken before the diagnosis. The results showed a high relative protection (inverse of the relative risk) in the first two years after a negative test, falling steadily as time since the last negative test elapsed. Even after 10 years, however, a considerable residual effect was observed.     

Prenatal cocaine exposure: Effects on the development of school-age children

The offspring of 28 women who reported light to moderate cocaine use during pregnancy were compared with those of 523 women who reported no cocaine use during pregnancy and none for the year prior to pregnancy. Subjects were participants in two prospective, longitudinal studies of prenatal substance use. Women were interviewed during their fourth and seventh months of pregnancy, at delivery, and at 8, 18, 36, and 72 months postpartum regarding cocaine, alcohol, marijuana, tobacco, and other drug use. At 6 years, children underwent physical examination, and their cognitive development, academic achievement, and behavior were assessed. The women in the cocaine group were more likely to be Caucasian and to use more alcohol, marijuana, tobacco, and other illicit drugs than those in the comparison group. When demographic and substance use differences between the groups were controlled, there were no significant effects of prenatal cocaine exposure on the growth, intellectual ability, academic achievement, or teacher-rated classroom behavior of the 6-year-old offspring. Children prenatally exposed to cocaine did show deficits in their ability to sustain attention on a computerized vigilance task.     

Automated hydrotherapy pool water treatment system

An automated hydrotherapy water treatment system was described that controls chemical pumps that maintain the pool's water pH and chlorine levels at the designated set points, regardless of the bather load. This system consists of sensing electrodes, a controller, and positive displacement pumps. Because outbreaks of waterborne infections have never been reported in facilities in which the pool water has been continuously maintained at pH 7.2 to 7.8 with a free available chlorine level of at least 1.0 ppm, we recommend that this type of water treatment system be installed in all public pools.     

Silver deposition in mouse glomeruli.

Administration of 6 mM silver nitrate in the drinking water of mice resulted in deposition within the glomerular basement membrane of silver granules which were detected on electron microscopy after 12 days. Larger aggregates were detected in the basement membrane and mesangium when silver ingestion was extended to 14 weeks. The silver deposits did not alter significantly over a period of 21 weeks after silver nitrate ingestion was stopped.