Exposure of cord blood to Mycobacterium bovis BCG induces an innate response but not a T-cell cytokine response.

Despite routine vaccination with Mycobacterium bovis bacillus Calmette-Guérin (BCG) soon after birth, tuberculosis in babies and adults remains epidemic in South Africa. The immune responses of the naïve newborn child and how they are affected by vaccination with BCG are as yet not fully understood. Immunity during pregnancy and in healthy human newborns may be skewed toward type 2 cytokine production; however, it is type 1 cytokines that are required for protection against M. tuberculosis infection. To better understand neonatal cytokine responses prior to and following exposure to mycobacteria, we have collected cord blood and peripheral blood samples and evaluated the cytokine response following ex vivo incubation with BCG. Gamma interferon (IFN-gamma), interleukin 10 (IL-10), IL-12, and low levels of IL-13 and IL-5 but no IL-4 were secreted into the culture supernatant of cord blood mononuclear cells. Intracellular staining showed that IL-10 and IL-12 were produced by monocytes and that IFN-gamma was produced by natural killer (NK) cells but not by CD4(+) or CD8(+) T cells. In contrast, in the peripheral blood samples collected from babies 13 weeks post-BCG vaccination, IFN-gamma was detected within CD4(+) and CD8(+) cells. Taken together, the data suggest a central role for Th1 cytokines in naïve as well as BCG-vaccinated neonates in the protective immune response to tuberculosis. NK cell-derived IFN-gamma produced in naïve neonates likely plays a key protective role via monocyte activation and the priming of a subsequent adaptive Th1 response.

Effect of niacin and atorvastatin on lipoprotein subclasses in patients with atherogenic dyslipidemia.

This study was conducted to determine the efficacy of atorvastatin and niacin on lipoprotein subfractions in patients with atherogenic dyslipidemia. This was a multicenter, randomized, open-label, parallel-design study of patients with total cholesterol >200 mg/dl, triglycerides between 200 and 800 mg/dl, and apolipoprotein B >110 mg/dl. Patients were randomly assigned to atorvastatin 10 mg or immediate release niacin 3,000 mg daily for 12 weeks following a low-fat diet stabilization period. Lipoprotein subclasses were measured by nuclear magnetic resonance spectroscopy. Atorvastatin and niacin both significantly reduced the concentrations of very low-density lipoprotein (VLDL) particles (-31% and -29%, respectively) and small low-density lipoprotein (LDL) particles (-44% and -35%, respectively). Niacin increased the concentration of large LDL (+75%). Atrovastatin reduced the number of LDL particles more than niacin (31% vs 14%). In patients with atherogenic dyslipidemia, both drugs had important effects on lipoprotein subfractions, which contributed to a reduction in coronary heart disease risk. The drugs equally reduced VLDL subclass levels. Niacin shifted the LDL subclass distribution toward the larger particles, more effectively converted patients from LDL phenotype B to phenotype A, and increased levels of the larger and perhaps more cardioprotective high-density lipoprotein particles. In contrast, atorvastatin preferentially lowered the concentration of small LDL particles without increasing levels of large LDL, and more effectively, reduced LDL particle numbers. Atorvastatin had a preferred LDL effect, whereas niacin had a preferred high-density lipoprotein effect.

Maternal prepregnancy weight and congenital heart defects in offspring.

To determine the relation between having an infant with a major heart defect and a mother's prepregnancy weight, we compared 1,049 Atlanta-area women who gave birth to liveborn or stillborn infants, each with a major heart defect, with 3,029 Atlanta-area women who gave birth to infants without birth defects. The infants of control women were randomly selected from birth certificates and were frequency-matched to the case group by race, birth hospital, and birth period from 1968 through 1980. After excluding diabetic mothers and adjusting for potential confounders, compared with average-weight women (body mass index 19.9--22.7), we found that underweight women (body mass index <16.5) were less likely to have a child with a major isolated heart defect [odds ratio (OR) = 0.64; 95% confidence interval (CI) = 0.43--0.97], whereas the OR was elevated among overweight or obese women (body mass index >26) (OR = 1.36; 95% CI = 0.95--1.93). Using average-weight women who did not take periconceptional multivitamins as the reference group, periconceptional multivitamin use was associated with a reduced OR for isolated heart defects among average-weight women (OR = 0.61, 95% CI = 0.36--0.99) and underweight women but not among overweight or obese women (OR = 1.69, 95% CI = 0.69--3.84).

Maternal multivitamin use and orofacial clefts in offspring.

BACKGROUND: Cleft lip with or without cleft palate (CLP) and cleft palate alone (CP) affect approximately 1 in 1000 infants and 1 in 2,500 infants, respectively. Studies of the relation between orofacial clefts and multivitamins or folic acid have been inconsistent. METHODS: We used data from a population-based case-control study involving 309 nonsyndromic cleft-affected births (222 with CLP, 87 with CP) and 3,029 control births from 1968 to 1980 to evaluate the relation between regular multivitamin use and the birth prevalence of orofacial clefts. RESULTS: We found a 48% risk reduction for CLP (odds ratio = 0.52, 95% confidence interval = 0.34-0.80) among mothers who used multivitamins during the periconceptional period or who started multivitamin use during the first postconceptional month, after controlling for several covariates. The risk reduction for CP was less than those for CLP (odds ratio = 0.81, 95% confidence interval = 0.44-1.52); however, a small number of CP cases limited interpretation. No risk reductions for CLP or CP were found for women who began multivitamin use in the second or third month after conception. CONCLUSIONS: The magnitude of the risk reduction in our study is comparable to those of other recent studies; our study does not support the contention that only large dosages of folic acid are needed to prevent orofacial clefts. More studies are needed to test the effects of multivitamins and varying dosages of folic acid on the recurrence and/or occurrence of orofacial clefts to provide information needed to determine possible prevention strategies. Published 2001 Wiley-Liss, Inc.

Maternal smoking and birth defects: validity of birth certificate data for effect estimation.

OBJECTIVES: The authors sought to assess the validity of birth certificate data for estimating the association between maternal smoking and birth defects. The US standard birth certificate includes check boxes for maternal smoking and for 21 congenital anomalies. The sensitivity and specificity of birth certificate data have been studied, but previous studies have not addressed the validity of these data for estimating the association between birth defects and maternal smoking or other risk factors. METHODS: US public-use natality data (1997-1998) were used to calculate the prevalence ratio (adjusted for maternal age, race/ethnicity, and education) for the association between maternal smoking and 13 defects/defect categories. All analyses were restricted to 45 states, New York City, and the District of Columbia because they collect both maternal smoking and birth defect data. RESULTS: Maternal smoking was associated with an increased prevalence of hydrocephaly (adjusted prevalence ratio [PR] = 1.24; 95% confidence interval [CI] = 1.08, 1.43), microcephaly (PR 1.47; 95% CI 1.15, 1.88), omphalocele/gastroschisis (PR 1.37; 95% CI 1.22, 1.53), cleft lip/palate (PR 1.35; 95% CI 1.25, 1.45), clubfoot (PR 1.62; 95% CI 1.49, 1.75), and polydactyly/syndactyly/adactyly (PR 1.33; 95% CI 1.23, 1.43 ). Previous studies have indicated an association between maternal smoking and gastroschisis, oral clefts, and clubfoot with effect estimates of similar magnitude to this study. CONCLUSIONS: These findings suggest that birth certificate data may be useful for exploratory or corroborative studies estimating the association between birth defects and some risk factors recorded on birth certificates.

Multivitamin use and mortality in a large prospective study.

To determine the relation between multivitamin use and death from heart disease, cerebrovascular disease, and cancer, the authors examined a prospective cohort of 1,063,023 adult Americans in 1982-1989 and compared the mortality of users of multivitamins alone; vitamin A, C, or E alone; and multivitamin and vitamin A, C, or E in combination with that of vitamin nonusers by using multivariate Cox proportional hazard models. Multivitamin users had heart disease and cerebrovascular disease mortality risks similar to those of nonusers, whereas combination users had mortality risks that were 15% lower than those of nonusers. Multivitamin and combination use had minimal effect on cancer mortality overall, although mortality from all cancers combined was increased among male current smokers who used multivitamins alone (relative risk (RR) = 1.13, 95% confidence interval (CI): 1.05, 1.23) or in combination with vitamin A, C, or E (RR = 1.16, 95% CI: 1.06, 1.26), but decreased in male combination users who had never (RR = 0.86, 95% CI: 0.74, 0.99) or had formerly (RR = 0.90, 95% CI: 0.82, 0.98) smoked. No such associations were seen in women. These observational data provide limited support for the hypothesis that multivitamin use in combination with vitamin A, C, or E may reduce heart disease and cardiovascular disease mortality, but add to concerns raised by randomized studies that some vitamin supplements may adversely affect male smokers.

A simplified method for isolation of large numbers of defined nephron segments.

We describe a simplified method for the isolation of large numbers of nephron segments from rat and rabbit kidneys. In contrast to most previous protocols, the kidneys are not perfused. After removal from the animal, the kidney is sliced and torn in pieces that are subsequently digested in culture medium containing 0.5 mg/ml of collagenase at 37 degrees C. If the preparation is agitated only very gently and infrequently, then the tissue gradually falls apart into a suspension containing long nephron fragments, often consisting of multiple connected segments. These are easily sorted into homogeneous segment populations that can be used for enzyme assays, protein extraction for immunoblotting, and RNA extraction for reverse transcription-polymerase chain reaction, all of which have been done successfully in our laboratory. For comparison, we have also examined cortical collecting tubule segments and cells prepared by the more rigorous protocol described previously (E. Schlatter, U. Fröbe, and R. Greger. Pflügers Arch. 421: 381-387, 1992). Even after the isolation of single cells in a Ca2+-free medium, the cells maintain their normal architecture and a distinct separation of apical and basolateral membranes.

Use of computer interview data to test associations between risk factors and pregnancy outcomes.

Computer interviews have been used in a variety of settings as a means of gathering data and providing health education information. The objective of this study was to determine whether data gathered from a computer interview have predictive validity in determining pregnancy outcomes. Pregnant women (N = 190) completed a computer-assisted interview to provide risk factor information. Medical records were reviewed to obtain prenatal and birth outcome information. Twenty-nine percent experienced prenatal complications and nearly half experienced problems related to labor and delivery. After known risk factors were controlled for, self-reported psychosocial problems, low social support, and substance abuse by the father were associated with pregnancy complications. An unbalanced diet and low social support were associated with lower infant birth weight. Findings suggest that data collected via computer interviews can provide useful risk factor screening information.

Is maternal obesity a risk factor for anencephaly and spina bifida?

To determine whether the risk of having an infant with anencephaly or spina bifida is greater among obese women than among average-weight women, we compared 307 Atlanta-area women who gave birth to a liveborn or stillborn infant with anencephaly or spina bifida (case group) with 2,755 Atlanta-area women who gave birth to an infant without birth defects (control group). The infants of control women were randomly selected from birth certificates and frequency-matched to the case group by race, birth hospital, and birth period from 1968 through 1980. After adjusting for maternal age, education, smoking status, alcohol use, chronic illness, and vitamin use, we found that, compared with average-weight women, obese women (pregravid body mass index greater than 29) had almost twice the risk of having an infant with spina bifida or anencephaly (odds ratio = 1.9; 95% confidence limits = 1.1, 3.4). A woman's risk increased with her body mass index: adjusted odds ratios ranged from 0.6 (95% confidence limits = 0.3, 2.1) for very underweight women to 1.9 for obese women.

The surveillance of birth defects: the usefulness of the revised US standard birth certificate.

To assess the sensitivity and positive predictive value of birth defects reported on the 1989 revision of the US Standard Birth Certificate, a population of 76,862 Atlanta-area births during 1989 and 1990 was used as the basis for comparing 771 birth certificates that reported birth defects with 2428 live-born infant records in a birth defects registry that uses multiple sources of case ascertainment. Only 14% of birth defects in the registry records were reported on birth certificates. After the analysis was restricted to defects recognizable at birth, the sensitivity and positive predictive value of the birth certificates were 28% and 77%, respectively. Birth certificates underestimate birth defect rates and should be used cautiously for birth defect surveillance and epidemiological studies.

Ion mobility spectrometry of halothane, enflurane, and isoflurane anesthetics in air and respired gases.

Three common gaseous anesthetics, halothane, enflurane, and isoflurane, were characterized by using ion mobility spectrometry (IMS)/mass spectrometry, and the dependence of product ion distributions on temperature and concentration was evaluated. At 40 degrees C and 500 ppb, negative ion mobility spectra in air largely consisted of monomer or dimer adducts with Br- or Cl- formed through dissociative electron capture of molecular neutrals. With increased temperature or decreased vapor concentrations, declustering and dissociation of product ions became pronounced. Ion-molecule reactions in the drift region of the IMS were evident as distortions in peak shape in the mass-resolved mobility spectra and in variable reduced mobilities for the same ions. A portable hand-held IMS was used for convenient, real-time detection of enflurane in respired gases following a controlled inhalation episode.

Vecuronium and porcine malignant hyperthermia.

Vecuronium was studied in eight malignant hyperthermia (MH) susceptible pigs for its potential to either trigger or prevent MH. Two sets of experiments were performed in the same animals: 1-hr total neuromuscular blockade by vecuronium infusion with thiopental anesthesia in the absence of invasive monitoring and halothane; and 1-hr infusion of vecuronium with thiopental anesthesia with invasive monitoring in the absence of and then, followed by 30-min infusion in the presence of halothane, followed in turn by exposure to halothane alone. One-hour infusion of vecuronium in the absence of halothane and invasive monitoring did not trigger MH in any animal. During the second set of experiments, MH, evidenced by rising rectal temperature, elevated end-tidal PCO2, mixed venous oxygen desaturation and muscle rigor, occurred in one animal during vecuronium alone, in four animals during vecuronium infusion and simultaneous exposure to halothane, and in three animals during exposure to halothane alone after recovery from vecuronium neuromuscular blockade. In view of the results of control experiments, the development of MH during vecuronium neuromuscular blockade before exposure to halothane was attributed to surgical stress rather than to vecuronium itself. It is concluded that vecuronium is not a trigger to MH in susceptible pigs.

Transport of L-cystine in isolated perfused proximal straight tubules.

Unidirectional fluxes of L-35S-cystine and intracellular 35S activity were measured in isolated perfused segments of rabbit proximal straight tubule. The absorptive (lumen-to-both) flux of L-35S-cysteine showed a tendency toward saturation within the concentration limits imposed by the low solubility of cystine (0.3 mmol . l-1). In contrast, for the bath-to-lumen fluxes, there was a linear relation between the bathing solution concentration of L-35S-cystine and the rate of 35S appearance in the lumen. Nonlinear fitting of both sets of unidirectional flux data gave a maximal cystine transport rate (Jmax) of 1.45 +/- 0.27 (SEM) pmol min-1 mm-1, a Michaelis constant (Km) of 0.20 +/- 0.07 mmol . l-1, and an apparent permeability coefficient of 0.27 +/- 0.11 pmol min-1 mm-1 (mmol . l-1)-1 (approximately 0.06 micrometer/s). The 35S concentration in the cell exceeded that in the lumen by almost 60-fold during the lumen-to-bath flux, and exceeded the bathing solution concentration by 4.7-fold during the bath-to-lumen flux. Thus cystine was accumulated by the cells across either membrane, but over 77% of the intracellular activity was in the form of cysteine. Although the presence of luminal L-lysine or cycloleucine inhibited the absorptive flux of cystine, neither amino acid affected the bath-to-lumen flux.

Flow dependence of fluid transport in the isolated superficial pars recta: evidence that osmotic disequilibrium between external solutions drives isotonic fluid absorption.

The present studies tested the hypothesis that osmotic disequilibrium between luminal and peritubular fluids is the driving force for net volume absorption in the isolated proximal straight tubule. Isolated tubule segments from superficial rabbit renal cortex were perfused at varying rates with a high chloride and bicarbonate-free solution as they were bathed with a normal bicarbonate-Krebs-Ringer buffer solution at 38 degrees C. Increasing the perfusion rate from congruent to 4 to congruent to 30 nl/min produced a monotonic increase in net volume absorption (Jv) from 0.18 +/- (sem) 0.03 to 0.62 +/- 0.08 nl . min-1. The chloride concentration in collected fluid samples rose from congruent to 137 to congruent to 147 mEq/liter over the same perfusion rate range. Ouabain (10(-4) m) added to the bathing solution inhibited Jv by a rate which varied from 0.20 to 0.28 nl . min-1 . min-1, depending on the perfusion rate. A mathematical model of the axial flows and transepithelial transport processes was developed. This model, and the experimental data, is consistent with the view that the driving force for isotonic fluid absorption in these tubules depends on the axial maintenance of osmotic disequilibrium between the perfusate and the bathing solution. Increasing the perfusion rate opposes osmotic equilibration by minimizing the extent to which dissipative fluxes of chloride and bicarbonate ions change the transepithelial chloride and bicarbonate concentration gradients, and by minimizing the tendency of the luminal cryoscopic osmolality to increase as volume absorption occurs.

Chloride transport in porous lipid bilayer membranes.

This paper describes dissipative Cl(-) transport in "porous" lipid bilayer membranes, i.e., cholesterol-containing membranes exposed to 1-3 x 10(-7) M amphotericin B. P(DCl) (cm.s(-1)), the diffusional permeability coefficient for Cl(-), estimated from unidirectional (36)Cl(-) fluxes at zero volume flow, varied linearly with the membrane conductance (Gm, ohm(-1).cm(-2)) when the contributions of unstirred layers to the resistance to tracer diffusion were relatively small with respect to the membranes; in 0.05 M NaCl, P(DCl) was 1.36 x 10(-4) cm.s(-1) when Gm was 0.02 ohm(-1).cm(-2). Net chloride fluxes were measured either in the presence of imposed concentration gradients or electrical potential differences. Under both sets of conditions: the values of P(DCl) computed from zero volume flow experiments described net chloride fluxes; the net chloride fluxes accounted for approximately 90-95% of the membrane current density; and, the chloride flux ratio conformed to the Ussing independence relationship. Thus, it is likely that Cl(-) traversed aqueous pores in these anion-permselective membranes via a simple diffusion process. The zero current membrane potentials measured when the aqueous phases contained asymmetrical NaCl solutions could be expressed in terms of the Goldman-Hodgkin-Katz constant field equation, assuming that the P(DNa)/P(DCl) ratio was 0.05. In symmetrical salt solutions, the current-voltage properties of these membranes were linear; in asymmetrical NaCl solutions, the membranes exhibited electrical rectification consistent with constant-field theory. It seems likely that the space charge density in these porous membranes is sufficiently low that the potential gradient within the membranes is approximately linear; and, that the pores are not electrically neutral, presumably because the Debye length within the membrane phase approximates the membrane thickness.