Cystic fibrosis, genetics, and DNA technology

Advances in molecular genetics are leading to changes in practice that have a direct impact on the obstetrician and gynecologist. New techniques of prenatal screening, diagnosis, and potentially therapy are rapidly evolving. Recent developments in cystic fibrosis, preimplantation genetics, fragile X syndrome, neurofibromatosis, muscular dystrophy, and Marfan syndrome are discussed.     

Characteristics of three vaginal flora patterns assessed by gram stain among pregnant women. Vaginal Infections and Prematurity Study Group.

This study was undertaken to define the characteristics and persistence of vaginal flora in 7918 pregnant women at 23 to 26 weeks' gestation. Vaginal smears were categorized as normal (predominant lactobacilli), intermediate (reduced lactobacilli), or positive for bacterial vaginosis. The women with normal flora were least likely to have elevated vaginal pH, amine odor, milky discharge, or colonization by Gardnerella, Bacteroides, or genital mycoplasmas. Women with intermediate vaginal flora had intermediate frequencies of these clinical signs and microorganisms. Group B streptococci and yeast were associated with normal or intermediate flora, whereas Neisseria gonorrhoeae and Chlamydia trachomatis were recovered more frequently from women with intermediate flora or bacterial vaginosis. Trichomonas vaginalis was most associated with intermediate flora. At follow-up, 81% of the women with normal flora had remained normal. Of the women with intermediate flora, 32% acquired bacterial vaginosis and 30% shifted to normal flora. Only 12% of the women with bacterial vaginosis had shifted to normal flora. We conclude that there are two primary stable vaginal flora patterns (normal flora or bacterial vaginosis) and a third less distinct transitional flora pattern between these two.     

Comparison of amniotic fluid disaturated phosphatidylcholine and the lecithin-sphingomyelin ratio in the prediction of fetal lung maturity

Although use of the lecithin-sphingomyelin (L/S) ratio has contributed to a reduction in the frequency of respiratory distress syndrome (RDS), its accuracy in pregnancies complicated by fetomaternal disease has been questioned. Disaturated phosphatidylcholine is the major active component of surfactant and has been advocated as being a more specific indicator of fetal lung maturity. A study of 105 pregnancies in which a L/S ratio and disaturated phosphatidylcholine assay were performed on amniotic fluid was carried out to ascertain if amniotic fluid disaturated phosphatidylcholine is indeed a more accurate predictor of RDS. The results of this investigation reveal no significant difference in the reliability of these two tests in predicting neonatal RDS. Five infants developed RDS with a mature L/S ratio ranging from 2.0 to 3.36, suggesting that the disaturated phosphatidylcholine assay may be a helpful adjunctive test in instances in which the L/S ratio is less than 3.5.     

Alternatives to HIV-1 RNA concentration and CD4 count to predict mortality in HIV-1-infected children in resource-poor settings

Cheaper, simpler alternatives to CD4 lymphocyte count and HIV-1 RNA detection for assessing the prognosis of HIV-1 infection are needed for resource-poor settings. However, little is known about the predictive value of alternative assays, in particular in children. We assessed the prognostic value of total lymphocyte count, immune complex-dissociated p24 antigen, white blood cell count, packed-cell volume (haematocrit), and serum albumin for mortality in 376 HIV-1-infected, mainly African-American or Hispanic children enrolled during March, 1988 to January, 1991. In a Cox proportional hazards model, including all assay-alternatives to CD4 and RNA, total lymphocyte count (p<0.0001) and serum albumin (p=0.0107) independently predicted mortality. Further assessment of these markers is warranted in resource-poor settings.     

The effect of comorbid illness on mortality outcomes in cardiac surgery

HYPOTHESIS: Comorbid conditions are associated with the risk of death from coronary artery bypass graft surgery. DESIGN: Prospective cohort study data were collected on patient and disease characteristics and comorbid conditions including hypertension, diabetes, obesity, vascular disease, chronic obstructive pulmonary disease, cancer (excluding nonmelanoma skin cancer), dialysis-dependent renal failure, liver disease, and dementia. Statistical analysis used logistic regression for the calculation of adjusted odds ratios (ORs) and 95% confidence intervals (CIs). SETTING: Regional cardiac surgery database. PATIENTS: A total of 27,239 consecutive patients undergoing isolated coronary artery bypass graft surgery. MAIN OUTCOME MEASURE: In-hospital mortality rate. RESULTS: The prevalence of comorbid conditions was as follows: hypertension, 64.3%; diabetes, 30.1%; obesity, 24.6%; severe obesity, 7.2%; vascular disease, 18.3%; chronic obstructive pulmonary disease, 10.9%; peptic ulcer, 7.5%; cancer, 3.8%; renal failure, 1.5%; liver disease, 0.6%; and dementia, 0.1%. After adjustment for patient and disease characteristics, including age, sex, previous cardiac surgery, priority of surgery, degree of left main coronary stenosis, number of diseased coronary arteries, and left ventricular ejection fraction, the following comorbid conditions were significant predictors of in-hospital mortality: diabetes (OR, 1.19; 95% CI, 1.01-1.40; P =.03), vascular disease (OR, 1.67; 95% CI, 1.41-1.97; P<.001), chronic obstructive pulmonary disease (OR, 1.57; 95% CI, 1.29-1.91; P<.001), peptic ulcer (OR, 1.34; 95% CI, 1.05-1.71; P =.02), and dialysis-dependent renal failure (OR, 3.68; 95% CI, 2.65-5.13; P<.001). There was no significant association between in-hospital mortality and hypertension, obesity or severe obesity, cancer, liver disease, or dementia. CONCLUSION: Even after adjustment for other patient and disease characteristics, comorbid conditions (especially diabetes, vascular disease, chronic obstructive pulmonary disease, peptic ulcer disease, and dialysis-dependent renal failure) are associated with significantly increased risk of death after coronary artery bypass graft surgery.     

Implementation of intelligent decision support systems in health care

The full implementation of any intelligent system in health care, which is designed for decision support, has several stages, from initial problem identification through development and, finally, cost-benefit analysis. Central to this is formal objectivist evaluation with its core component of inherent performance of the outputs from these systems. A Medline survey of one type of intelligent system is presented, which demonstrates that this issue is not being addressed adequately. Lack of criteria for dealing with the outputs from these "black box" systems to prescribe adequate levels of inherent performance may be preventing their being accepted by those in the health-care domain and, thus, their being applied widely in the field.     

Childhood immune thrombocytopenic purpura

Childhood immune thrombocytopenic purpura (ITP) is acute and generally seasonal in nature, suggesting that infectious or environmental agents may trigger the immune response to produce platelet-reactive autoantibodies 4 to 8 weeks following an infection. In general, the patient is well apart from the diffuse bruising and petechiae indicative of a profound thrombocytopenia. Over a period of 6 months, the thrombocytopenia resolves in approximately 85% of children, while the remaining 15% with persistent platelet consumption are designated as chronic ITP patients. The peak age of acute ITP is 2 to 5 years of age, a period when children experience the greatest frequency of viral infections. Children with the chronic form of ITP mirror the adult phenotype, in that females predominate, and there is no seasonal fluctuation of the disease. Evidence from our laboratory suggests that the activated platelet itself may play a role in perpetuating autoantibody production and immune dysregulation associated with ITP. Current data on lymphocyte studies and cytokine alterations noted in response to the variety of regimens used in children with ITP suggest that acute ITP is accompanied by autoantibodies to GPIb and a cytokine profile that is proinflammatory in nature. Early recognition of the immune dysregulation driving acute versus chronic ITP will distinguish those children who might benefit from immunotherapy versus those who will recover without therapeutic intervention.