Nonstress test assessment of twins.

Twin pregnancies have higher perinatal morbidity and mortality rates than singleton pregnancies. Researchers have demonstrated that one major benefit of prenatal care in the twin gestation is reduced fetal death rate. This study to determine the relationship of nonstress tests (NSTs) to pregnancy outcome in twin gestations comprised 665 women who delivered at Los Angeles County-University of Southern California Women's Hospital from January 1985 to January 1989. These patients, all of whom had prenatal care (PNC), were subdivided into two groups: (1) PNC and NSTs and (2) PNC and no NSTs. The groups did not differ statistically with regard to gravidity, parity and abortions. NSTs were selectively done on twin gestations complicated by discordancy or other fetal/maternal complications. Ten pregnancies were complicated by fetal demise of one or both twins in patients who received prenatal care without NSTs. Among the NST group there was one fetal demise. Although the NST group had fewer fetal deaths, the reduction was not statistically significant (P = .062). Infant birth weight was identified as a confounder because the NST group had a statistically higher mean birth weight. Definitive proof of the ability of NSTs to reduce the fetal death rate in twin gestations complicated by discordancy or other pregnancy complications awaits a large, prospective, randomized trial.     

Severe adolescent head injury: Implications for transition into adult life

This report describes the outcomes of 28 children who had severe head injuries between 13–18 years of age. All were unconscious at least 24 hours and have been followed at least 2 years after injury. At present, their ages range from 18 to 27 years. Their educational achievements, social activities, marital status, functional independence, and employment at follow-up are described.     

Distribution of circulation-derived endothelial progenitors following systemic delivery.

Cells with an endothelial phenotype can be cultured from peripheral blood. These cells include cells of a monocytic origin with endothelial features (culture-modified mononuclear cells, CMMCs) and, at later time points, blood outgrowth endothelial cells (BOECs). Both are promising candidates for systemic cell-based cardiovascular therapies and each may have unique capabilities. Indeed, the combined use of both cell types has been shown to have synergistic therapeutic features requiring simultaneous delivery. However, the majority of preclinical studies of cell delivery have used splenectomized animals to increase systemic distribution. The goal of this study was to directly compare the distribution of these two cell types following systemic delivery in an intact animal model. A similar pattern of delivery was seen following delivery of both cell types with detection in the lung, liver, bone marrow, and spleen. Taken together, the data suggest that strategies using systemic delivery of circulation-derived cells must consider the distribution and efficiency of delivery in intact animals.     

Acrocentric interconnections and NOR variants in human lymphocytes

Acrocentric interconnections and NOR (nucleolus organizer region) variants are frequently observed in silver-stained metaphase preparations from lymphocytes of phenotypically normal individuals. The types of interconnections and of NOR variants are outlined. It is speculated that the satellite acrocentrics (both normal and variant) are the consequence of breakage and recoiling of these interconnections. Awareness of these two features of the human genome may facilitate understanding of the NOR/nucleolus interaction(s) in such important processes as nucleolus formation and in development and/or diagnosis of disease states (i.e., malignancy).     

Protective factors related to antisocial behavior trajectories

A group of 115 fifth- and sixth-grade Latino students were surveyed at the beginning and the end of the school year before their transition to middle or junior-high school about their engagement in antisocial behaviors and about individual, social, and behavioral protective factors. The best predictors of decreases in antisocial behavior for these students, above and beyond variance for initial ratings and gender, were student perceptions of social support, parent supervision, and classroom participation. The importance of keeping students engaged in school academic work as a protection against antisocial behavior is emphasized as well as the need to help students gain skills necessary to access support for this academic work.     

Molecular mechanism for loss of visual cortical responsiveness following brief monocular deprivation

A dramatic form of experience-dependent synaptic plasticity is revealed in visual cortex when one eye is temporarily deprived of vision during early postnatal life. Monocular deprivation (MD) alters synaptic transmission such that cortical neurons cease to respond to stimulation of the deprived eye, but how this occurs is poorly understood. Here we show in rat visual cortex that brief MD sets in motion the same molecular and functional changes as the experimental model of homosynaptic long-term depression (LTD), and that prior synaptic depression by MD occludes subsequent induction of LTD. The mechanisms of LTD, about which there is now a detailed understanding, therefore contribute to visual cortical plasticity.     

Incomplete rescue of cystic fibrosis transmembrane conductance regulator deficient mice by the human CFTR cDNA

We have used a mouse model to study the ability of human CFTR to correct the defect in mice deficient of the endogenous protein. In this model, expression of the endogenous Cftr gene was disrupted and replaced with a human CFTR cDNA by a gene targeted 'knock-in' event. Animals homozygous for the gene replacement failed to show neither improved intestinal pathology nor survival when compared to mice completely lacking CFTR. RNA analyses showed that the human CFTR sequence was transcribed from the targeted allele in the respiratory and intestinal epithelial cells. Furthermore, in vivo potential difference measurements showed that basal CFTR chloride channel activity was present in the apical membranes of both nasal and rectal epithelial cells in all homozygous knock-in animals examined. Ussing chamber studies showed, however, that the cAMP-mediated chloride channel function was impaired in the intestinal tract among the majority of homozygous knock-in animals. Hence, failure to correct the intestinal pathology associated with loss of endogenous CFTR was related to inefficient functional expression of the human protein in mice. These results emphasize the need to understand the tissue- specific expression and regulation of CFTR function when animal models are used in gene therapy studies.      

Persistent genetic isolation in outport Newfoundland

The historical development of genetic isolation has been evaluated for three outport Newfoundland study areas. An attempt was made to ascertain all livebirths in each study area, and determine the parentage of each. Data from records of baptism and marriage were used for this, supplemented with other historical and ethnographic information. Parent-offspring migration was used as a measure of genetic exchange between subpopulations within study areas, and gene flow into the study areas. Currently, 1-8% of parents originate outside the study areas; these rates are low compared to earlier periods, and compared to present-day rates for European isolate populations. Average kinship was estimated, to measure genetic relatedness within and between subpopulations of each area and the potential for random inbreeding; these values, which are minimum estimates, are now at historically high levels. Increased migration into the study areas, which would decrease average kinship, is not likely. Thus, any regionally or locally elevated frequencies of deleterious alleles will persist, and must be taken into account in providing genetic counseling and evaluating the utility of local screening programs.