Morbidity studies of workers exposed to whole body vibration

Insurance claims for medical services submitted on behalf of a group of workers in the construction industry were collected over a 20-month period. The morbidity experience of those workers exposed to whole body vibration was contrasted with that of an unexposed control group eligible for benefits under the same plan. Using Mantel-Haenszel adjustment for age and experience, a significantly elevated relative risk was found among the exposed group in three of the thirty disease categories studied. In no disease category did the control group possess a significantly higher risk of requiring medical services. A striking proportion of the disease categories showed an initial increase in risk for exposed workers followed by a decrease with experience. This pattern suggests a selection process in which workers leave exposed-group jobs as they become afflicted with certain disease conditions.

Sex-related mortality in developing chicken (Gallus domesticus) embryos

A total of 528 fertilized chick eggs (including 48 nonfertile eggs) were examined for viability and chromosomal sex after 60 to 90 h of incubation. Of those that contained embryos, 196 were male (ZZ), 183 were female (ZW), and 101 were of undetermined sex. The embryonal mortality rate was 18% for both the homogametic and the heterogametic sex and 19% for the undetermined sex groups. The results are consistent with the hypothesis that the sex ratio among live embryos does not deviate from 50 % male during the early incubation period and that recessive sex-linked lethal genes do not contribute significantly to a difference in mortality between the sexes in an ordinary breeding flock. It is suggested that sexing early chick embryos by chromosome morphology may require relatively small samples to detect lethal recessives induced by potentially mutagenic agents.

Removing bronchial secretions. Intratracheal suction and related measures

Intratracheal suction is a proved adjunct in the maintenance of normal homeostasis of the tracheobronchial tree after major abdominal and thoracic operations. A sound understanding of the principles and techniques of intratracheal suction and intelligent use at appropriate intervals are primarily the responsibility of the nursing staff. If intratracheal suction is ineffective, other measures must be employed, including bronchoscopy or tracheostomy.