Sex differences and sustained excess in mortality among discordant twins in Matlab, Bangladesh: 1977-1985

This paper reports findings from a study that compared survival of 204 pairs of liveborn twins discordant for sex and a random sample of 2371 singleton live births from the same population in Matlab, Bangladesh during the period 1977-1985. The discordant twins showed no evidence of sex differential in neonatal survival. They had neonatal mortality of 287 and infant mortality of 468, both per 1000 live births. These rates were respectively five and four times the rate for singletons in the study. Survival from 12 months through age nine years was similar overall for both discordant twins and singletons for each sex. However, higher female than male mortality was present among discordant twins after the first few months of life. This differential was most prominent during the second year of life and appeared wider than that observed for the singletons.

The distribution of immunoreactive interferon-alpha in normal human tissues

The cellular distribution of immunoreactive interferon-alpha (IFN-alpha) was studied in formalin-fixed paraffin-embedded normal human tissues from 36 different organs. These samples were drawn from over 300 individuals none of whom had evidence of viral infection. Tissue histiocytes from all organs in the body, with the exception of brain and renal cortex and medulla, stained positively for IFN-alpha. Kupffer cells, pulmonary alveolar macrophages and lymph node macrophages were also positive. Parenchymal cells in some other organs also appeared to contain immunoreactive IFN-alpha. These included cuboidal lining cells of the choroid plexus in the brain, thyroid follicular cells, pituitary endocrine cells, adrenocortical cells and parathyroid principal and oxyphil cells. These findings are compatible with previous suggestions that IFN-alpha may be synthesized and released in the absence of viral infection and may thus have a role in normal physiology. The presence of IFN-alpha in most cells of the mononuclear phagocyte system suggests that these cells may play a major part in defence against viral infection.

Study of interfering substances in a simple, new spectrophotometric assay for phenylalanine ammonia-lyase

A study of interfering substances in a new spectrophotometric assay for phenylalanine ammonia-lyase has been made. None of the commonly interfering compounds interfere in the assay to any significant extent. The assay has been employed for the partial purification of the enzyme from mint leaves (Mentha viridis'L).