Effect of maternal and infant covariates on sibship correlation in birth weight

Birth weight on 12,644 singleton infants from 6,196 sibships born in Maryland between 1980 and 1984 were used to estimate the effects of nine maternal and infant covariates on the sibship correlation in birth weight. Assuming a homogeneous correlation across all families, the estimated intraclass correlation was 0.4664 (+/- 0.0099). This high sibship correlation makes it possible to predict, with reasonable accuracy, the birth weight of a child given information on previous sibs, as well as covariates on the mother and/or infant pertinent to a given pregnancy. The reduction in variance associated with incorporating information on the nine covariates used here was approximately equal to that obtained by conditioning on a single previous sib. Testing for heterogeneity in correlation among different groups of families showed that a crude measure of parity (first live birth vs. other), time between births, mother's marital status, and maternal age at the birth of the last child significantly influenced the sibship correlation in birth weight.     

The use of the monoclonal antibody Ki-67 in the identification of proliferating cells: application to surgical neuropathology

In order to test its potential application to surgical neuropathology, the monoclonal antibody Ki-67 was used to demonstrate immunohistochemically the proliferating cells in 40 neoplasms of the nervous system. The antibody, which reacts with a nuclear protein expressed in the G1, G2, S, and M phases of the cell cycle, was demonstrated in frozen sections of all lesions. The highest incidence of stained nuclei was found in a metastatic carcinoma (57%). The percentage of stained cells in gliomas was in general agreement with the histologic grade and known biologic behavior of the lesions, ranging from 0.6% in a pilocytic astrocytoma to 12.4% in a glioblastoma multiforme. In the fibrillary astrocytic neoplasms of low cellularity, there were good correlations between the percentages of stained cells and the degrees of nuclear pleomorphism and chromatin density. In meningiomas, schwannomas, and a cerebellar hemangioblastoma, the fractions of labeled nuclei were less than 1%. The percentage of stained cells in pituitary adenomas showed considerable variation among the four cases (0.2-1.5%), the biologic significance of which is unknown. In four of the above cases, Ki-67 staining was performed on air-dried squash preparations with excellent visualization of immunoreactive nuclei. In one case, a hemangioblastoma, no stained nuclei were seen. The results confirm that Ki-67 staining is technically suitable as a diagnostic method, with good correlations between frozen sections and smear preparations. Determination of the replicating cell fraction could become an important additional criterion to predict the biologic behavior of nervous system neoplasms.     

FEASIBILITY OF CONDUCTING CARDIOVASCULAR OUTCOME RESEARCH IN AUSTRALIAN GENERAL PRACTICE: RESULTS FROM THE ANBP2 PILOT STUDY

1. The present study aimed to determine the feasibility of conducting a 5 year cardiovascular outcome trial of the treatment of 6000 elderly hypertensive patients in Australian general practices. 2. General practitioners (GPs) were invited to participate by mail and personal follow-up. Patient records were reviewed to identify subjects for a blood pressure (BP) screening programme. Blood pressure was measured on three occasions and eligible subjects were included if the average BP was 160 mmHg systolic or 90 mmHg diastolic if systolic BP was 140 mmHg. 3. Seven hundred and forty-one GPs were approached and 89 were enrolled in the study (12% of mail invites and 75% of those receiving a personal contact). In 16 practices where screening was completed, 82 000 records were reviewed to identify 4% patients eligible for screening. Twenty-two per cent of eligible subjects attended screening. Of 1938 subjects screened, 180 (9%) had BP 5=160/90 mmHg. Forty-seven percent of subjects (n = 916) were receiving antihypertensive therapy and 184 (20%) were withdrawn from therapy. One hundred and sixteen (63%) of these subjects had BP return to study entry levels within 6 weeks. Fifty-seven newly diagnosed and 81 previously treated subjects were randomized (7% of the screened population). 4. Based on the high participation rate of GPs, the response rate of patients to attend a BP screening programme and the 7% randomization to screening ratio for entry into the study, the ANBP2 pilot study has demonstrated that it is feasible to recruit subjects from Australian general practices to a cardiovascular outcome trial.     

Risk Assessment as a Management Tool Used to Assess the Effect of Pesticide Use in an Irrigation System,Situated in a Semi-Desert Region

A preliminary study undertaken by the CSIR in July 1993 on the health effects of aerial crop spraying of pesticides in the Vaalharts irrigation area in South Africa indicated that potential health risks could exist for the inhabitants of this area. An extensive scientific health risk assessment and epidemiological study to determine the actual health risks, is very expensive and requires medical and financial justification. The aim of this study was to develop a theoretical health risk model, which could be used as a predictive tool to determine as accurately as possible from the data available if a complete scientific health risk assessment study is justified. The actual amounts of pesticides sold in the Vaalharts area by two major pesticide manufacturers were used to perform a theoretical health risk assessment. The risks were assessed by making use of RISK*ASSISTANT, a computer modeling system and chemical database. The United States Environmental Protection Agency's (EPA) health risk model was applied to the data to identify the hazards, assess the exposures and dose response, and characterize the risks. Three exposure scenarios, namely, the ingestion of food and water and the inhalation of air were evaluated. The method used to calculate the risks varied according to the type of health hazard and the results were characterized accordingly. The acute health effects due to exposure to pesticides are well known and the risks are easy to determine. However, the risks associated with chronic health hazards were more difficult to calculate. For this reason a ranking model was developed which made use of a point scoring system. This model highlights those pesticides which have the greatest possibility of causing chronic health effects. From the results it can be concluded that very large amounts of pesticides are used in the Vaalharts area and that the community might be at risk to chronic health effects. Although the theoretical health risk assessment model was successfully used in this study, its effectiveness as a predictive tool still has to be proven by a complete scientific study. Received: April 1996/Revised: 21 July 1996     

Preoperative care of infants with nephroblastoma. The International Society of Pediatric Oncology 6 experience.

The International Society of Pediatric Oncology (SIOP) recommends preoperative treatment in the management of eligible patients with Wilms' tumor. Until 1980, children younger than 12 months of age (infants) at diagnosis had been excluded from the SIOP trials. SIOP 6, conducted from 1980 to 1987, was the first SIOP study to include infants older than 6 months of age. This retrospective analysis of 145 infants registered to SIOP 6 demonstrates that in infants older than 6 months and having favorable histology (FH), a two-drug preoperative chemotherapy (CT) regimen of 4 weeks significantly ameliorated stage distribution as determined at delayed surgery but did not affect a good outcome. However, the CT dose utilized in SIOP 6 resulted in an unacceptable toxicity in this age group, and SIOP 9, the new SIOP study of Wilms' tumor, recommends a reduced dose of CT in infants. Preoperative CT is not recommended in infants younger than 6 months of age. Specifically, the high incidence (29%) of mesoblastic nephroma in this age group does not justify such an approach. Histopathologic diagnosis should be obtained in these patients before any treatment.     

Inhibin and age in men

OBJECTIVE: Normal elderly men are reported to have decreased testicular function despite elevated gonadotrophin levels. We wished therefore to determine if changes in testicular function occur over the age range 19-60 years. DESIGN: Single fasting blood samples were obtained between 0800 and 0900 h. PATIENTS: Working men in a large industrial company between the ages of 19 and 60 years participated in the study. MEASUREMENTS: FSH, serum immunoreactive inhibin and total testosterone were measured, the latter two as measurements of Sertoli and Leydig cell function respectively. RESULTS: The mean baseline serum immunoreactive inhibin level was significantly lower in men from the older age groups, 31-40 years (479 U/l), 41-50 years (439 U/l) and 51-60 years (415 U/l) than in men from the youngest age group, 21-30 years (613 U/l) while serum FSH was higher in men from the older age groups, 41-50 years (3.7 IU/l) and 51-60 years (6.1 IU/l) than in men from the youngest age group, 21-30 years (2.6 IU/l). There appears to be a change in both FSH and inhibin production, consistent with a primary decline in testicular function. There was no significant difference in testosterone levels between the older age group, age 51-60 years and the younger age group, age 21-30 years. However, testosterone levels were significantly lower in the 41-50 year age group, when compared with the 21-30 year, this significance levelling out at about age 45 years. CONCLUSION: The data are consistent with the hypothesis that immunoreactive inhibin reflects inhibin bioactivity, and that inhibin plays a role in the feedback control of FSH secretion in men.