Regression analysis of doubly censored failure time data with applications to AIDS studies

In many epidemiological studies, the survival time of interest is the elapsed time between two related events, the originating event and the failure event, and the times of the occurrences of both events are right or interval censored. We discuss the regression analysis of such studies and a simple estimating equation approach is proposed under the proportional hazards model. The method can easily be implemented and does not involve any iteration among unknown parameters, as full likelihood approaches proposed in the literature do. The asymptotic properties of the proposed regression coefficient estimates are derived and an AIDS cohort study is analyzed to illustrate the proposed approach.     

A process of events with notification delay and the forecasting of AIDS

Analysis and prediction of a point process are studied when there is delay in notifying the occurrence of events. A primarily parametric approach is taken to studying the rate of the underlying process and to predicting future properties of the system. Data on AIDS are used in illustration.     

Supernumerary bisatellited chromosome in a family ascertained through a patient with Sturge-Weber syndrome.

The presence of a structurally abnormal extra chromosome in a patient with Sturge-Weber syndrome and several members of her family is described. With routine techniques the abnormal chromosome is slightly submetacentric, of the size of a G group chromosome and shows satellites on both arms. C-banding suggested the presence of 2 centromeric regions rather than one, and to explain this finding, in addition to the segregation of the abnormal chromosome through 3 generations and why only one centromere is visible with the usual cytogenetic technique, an hypothesis is advanced suggesting that it resulted from an unusual type of Robertsonian translocation, in which one of the breacks involved directly the centromere of an acrocentric producing a partially dicentric bisate-lited chromosome. The association of Sturge-Weber syndrome with the chromosome abnormality is thought to be fortuitous and the lack of clinical manifestations of all members of this family with the abnormal chromosome, including one with two extra ones, is explained by the fact that it was almost entirely formed by heterochromatic material. The usefulness of C-banding in the study of this patient is strongly emphasized.     

The micro-computer card. Possible applications to transfusion from A to Z

Following characteristics of micro-computer cards: inaccessibility to selected secret information; strong resistance to aggressive external agents; impossibility of altering stored data without destroying it; instant reading and reproduction by authorized services; make them a perfect material for building up individual records of civil and biological data. Their application to blood transfusion allows increased safety not only for blood donation registrations, but above all when transfusion takes place; they may also be used as credit cards for health expenditures. They consequently serve as real LIFE cards.     

Measurement of biological information with applications from genes to landscapes

Biological diversity is quantified for reasons ranging from primer design, to bioprospecting, and community ecology. As a common index for all levels, we suggest Shannon's (S)H, already used in information theory and biodiversity of ecological communities. Since Lewontin's first use of this index to describe human genetic variation, it has been used for variation of viruses, splice-junctions, and informativeness of pedigrees. However, until now there has been no theory to predict expected values of this index under given genetic and demographic conditions. We present a new null theory for (S)H at the genetic level, and show that this index has advantages including (i) independence of measures at each hierarchical level of organization; (ii) robust estimation of genetic exchange over a wide range of conditions; (iii) ability to incorporate information on population size; and (iv) explicit relationship to standard statistical tests. Utilization of this index in conjunction with other existing indices offers powerful insights into genetic processes. Our genetic theory is also extendible to the ecological community level, and thus can aid the comparison and integration of diversity at the genetic and community levels, including the need for measures of community diversity that incorporate the genetic differentiation between species.     

Understanding physicians' response to AIDS.

Attempts to comprehend physicians'' extreme reaction to AIDS (acquired immune deficiency syndrome) have met with great difficulty since the disease brings into question traditional norms and assumptions. As the medical profession struggles to develop guidelines and policies to help it deal with this disease, it can draw on very little systematic research on the effect of AIDS on physicians'' attitudes and practices. We suggest a framework developed from the literature on physicians'' and society''s response to other disorders that would provide a basis for organizing the ever-increasing amount of information on physicians and AIDS and would guide systematic research aimed at understanding and predicting physicians'' participation in the prevention and management of AIDS. Within this framework we consider how characteristics of the disease, elements of the health care system and physicians'' attitudes interact to influence clinical and personal practices. AIDS had led to new delineations of physicians'' responsibility, modification of prevailing beliefs about physician autonomy and thus a redefinition of the role of the physician in North America.     

Isolation of Mycobacterium avium-intracellulare-scrofulaceum complex from faeces of patients with AIDS.

Thirty faecal specimens from 22 patients with the acquired immune deficiency syndrome were examined by microscopy after Ziehl-Neelsen staining and by culture after decontamination with sodium hydroxide. Thirteen specimens (from 11 patients) were positive for Mycobacterium avium-intracellulare-scrofulaceum on culture, and only five of these on Ziehl-Neelsen staining. Five of the 11 patients had evidence of disseminated infection. Lipid analysis showed six of the nine strains tested to be indistinguishable. These findings support the theory that the gastrointestinal tract is a portal of entry for the organism.