Estimating the prevalence of malformation of the heart in the first year of life using capture-recapture methods

The authors estimated the prevalence of heart malformation during the first year of life, using five data sets with varying degrees of completeness from two English regional health authorities. These areas covered a total population of 6,872,000. Analysis was carried out using capture-recapture methods, including log-linear modeling, on data collected between June 1993 and August 1994. A large number of cases in the community were unrecorded by any of the current sources of information. In South East Thames, where an antenatal training screening program for detecting heart malformations had been implemented in the late 1980s, the estimated prevalence rate varied from 5.5 per 1,000 births (95% confidence interval (CI): 3.5, 10.8) to 9.0 per 1,000 births (95% CI: 6.4, 14.2), depending on the assumptions in the model and the number of sources used in the analysis. In the Wessex region, which did not have a formal training program, prevalence was lower and varied little, from 4.3 per 1,000 (95% CI: 3.4, 6.0) to 5.1 per 1,000 (95% CI: 4.0, 7.2), according to assumptions. These two estimates were reasonable rates in comparison with reports in the literature. This analysis was helpful in demonstrating that the training program designed to identify severe heart malformations during the antenatal period in one of these regions had no lasting impact on prevalence.

Visualizing and characterizing white matter fiber structure and architecture in the human pyramidal tract using diffusion tensor MRI

We used diffusion tensor imaging to assess diffusion anisotropy in the pyramidal tract in ten young, and ten elderly subjects (five males and five females in each group). The purpose of this study was to define normative values for anisotropy at different anatomic levels of the brainstem as well as to assess differences due to age, gender, and laterality. In all subjects, anisotropy was highest in the cerebral peduncle, lowest in the caudal pons, and intermediate in the medulla. In the pons and medulla the regional variability was high, with significant differences in anisotropy even between contiguous slices. Multifactorial ANOVA (performed using the average value of anisotropy within each region of interest) revealed that elderly subjects had significantly lower values than young subjects in the cerebral peduncle, with no differences in the pons and medulla. No significant differences in anisotropy due to gender and side were found. The differences in anisotropy at different levels of the brainstem reflect differences in the local architecture of white matter fibers. Anisotropy is high in the cerebral peduncle because fibers have a highly ordered arrangement, while in the pons and medulla, anisotropy is lower because the local fiber architecture is less coherent due to the presence of other fibers and nuclei. The biologic meaning of the intergroup differences in anisotropy is discussed in light of the structure and architecture of the tissue under investigation. We also consider potential sources of artifacts, such as noise and motion, partial volume contamination, anatomic mismatching, and the use of inappropriate statistical tests. We conclude that the age-related decrease in anisotropy in the cerebral peduncle is not artifactual but rather reflects subtle structural changes of the aging white matter. Our study however shows that caution must be exercised in interpreting diffusion anisotropy data.

Expression of mouse mammary tumor virus superantigen mRNA in the thymus correlates with kinetics of self-reactive T-cell loss

Mouse mammary tumor virus (MMTV) encodes a superantigen (Sag) that is expressed at the surface of antigen-presenting cells in conjunction with major histocompatibility complex (MHC) type II molecules. The Sag-MHC complex is recognized by entire subsets of T cells, leading to cytokine release and amplification of infected B and T cells that carry milk-borne MMTV to the mammary gland. Expression of Sag proteins from endogenous MMTV proviruses carried in the mouse germ line usually results in the deletion of self-reactive T cells during negative selection in the thymus and the elimination of T cells required for infection by specific milk-borne MMTVs. However, other endogenous MMTVs are unable to eliminate Sag-reactive T cells in newborn mice and cause partial loss of reactive T cells in adults. To investigate the kinetics of Sag-reactive T-cell deletion, backcross mice that contain single or multiple MMTVs were screened by a novel PCR assay designed to distinguish among highly related MMTV strains. Mice that contained Mtv-17 alone showed slow kinetics of reactive T-cell loss that involved the CD4(+), but not the CD8(+), subset. Deletion of CD4(+) or CD8(+) T cells reactive with Mtv-17 Sag was not detected in thymocytes. Slow kinetics of peripheral T-cell deletion by Mtv-17 Sag also was accompanied by failure to detect Mtv-17 sag-specific mRNA in the thymus, despite detectable expression in other tissues, such as spleen. Together, these data suggest that Mtv-17 Sag causes peripheral, rather than intrathymic, deletion of T cells. Interestingly, the Mtv-8 provirus caused partial deletion of CD4(+)Vbeta12(+) cells in the thymus, but other T-cell subsets appeared to be deleted only in the periphery. Our data have important implications for the level of antigen expression required for elimination of self-reactive T cells. Moreover, these experiments suggest that mice expressing endogenous MMTVs that lead to slow kinetics of T-cell deletion will be susceptible to infection by milk-borne MMTVs with the same Sag specificity.

Molecular cloning, expression, localisation and functional characterisation of a rabbit SULT1C2 sulfotransferase

The importance of sulfotransferases in xenobiotic metabolism is gaining recognition. The gastrointestinal (GI) tract is a major portal of entry for many xenobiotics, yet little is known about the contribution of sulfotransferases to detoxication or bioactivation metabolism in these tissues. To this end, isolation and characterisation of sulfotransferases expressed in the stomach of rabbits was undertaken. A unique sulfotransferase cDNA (GenBank Accession No. AF026304) was isolated from a rabbit stomach cDNA library. This cDNA was 1439 base pairs (bp) long and has an open reading frame of 888 bp. On expression of the cDNA in both COS cells and E. coli, a protein molecular weight of 34 kDa was detected on SDS-PAGE. Immunoblotting using an antibody raised in goats against the bacterially expressed protein detected expression of the protein in GI tract tissues. The 34 kDa immunoreactive band was detected in rabbit GI tract tissues (stomach, duodenum, jejunum, ileum, colon, caecum and rectum), liver and kidneys, but not in the lungs (n = 3). The human ortholog (GenBank Accession No AF026303) of the rabbit enzyme was cloned from a human stomach cDNA library. These two enzymes share 84% amino acid sequence identity and have been termed 1C2 sulfotransferases. When functional and kinetic characterisation of the recombinant rabbit and human proteins was carried out using 16 known ST substrates, detectable sulfonation activity was observed only with p-nitrophenol (with Km values of 2.2 mM and 13.3 mM, respectively). In conclusion, we have identified a rabbit GI tract sulfotransferase belonging to a newly defined sulfotransferase subfamily.

Second-trimester maternal serum inhibin A concentration as an early marker for preeclampsia

OBJECTIVE

Maternal serum inhibin A concentration is elevated in established preeclampsia. The aim of this study was to investigate whether this relationship antedates the appearance of the classic signs of preeclampsia.

STUDY DESIGN

A retrospective analysis was performed on trisomy 21 screening data from 685 women at between 15 and 19 weeks' gestation. The main outcome measures were preeclampsia and small for gestational age (<5th percentile) infants.

RESULTS

Preeclampsia developed in 35 women (5.5%). Women with inhibin A concentration >2.0 multiples of the median were significantly more likely to acquire preeclampsia (P <.00001) and to be delivered of a small for gestational age infant (<5th percentile, P <.00001) than were women with inhibin A concentration </=2.0 multiples of the median. The odds ratios were 9.4 (95% confidence interval 4.6-19.3) for development of preeclampsia and 18.2 (95% confidence interval 6. 0-54.8) for preeclampsia necessitating delivery at <37 weeks' gestation. The association remained statistically significant for nulliparous women.

CONCLUSION

Elevated maternal inhibin A concentration in the second trimester was strongly associated with a subsequent risk of preeclampsia. The potential role of second trimester inhibin A measurement in a screening strategy for preeclampsia needs to be investigated further.

Homeoproteins CDP and SATB1 interact: potential for tissue-specific regulation

Homeoproteins are known to participate in development and cell type specification. The homeoproteins CCAAT displacement protein (CDP) and special AT-rich sequence binding protein 1 (SATB1) have been shown to bind to nuclear matrix-associated regions and to act as repressors of many cellular genes. Moreover, binding of SATB1 to the mouse mammary tumor virus (MMTV) promoter region dramatically affects the tissue-specific transcription of this retrovirus. Because protein-protein interactions are a common means of regulating homeoprotein function, we tested whether SATB1 and CDP interact in vivo and in vitro. SATB1 interacted with CDP through its DNA-binding domain, as demonstrated by glutathione S-transferase (GST) pull-down assays. GST pull-down assays also showed that CDP associated with SATB1 through three of its four DNA-binding domains (CR1, CR2, and the homeodomain). SATB1-specific antisera, but not preimmune sera, precipitated CDP from nuclear extracts, and CDP-specific antisera precipitated SATB1 from the same extracts. Far-Western blotting detected interaction of SATB1 and CDP in several different tissue extracts. Association of purified SATB1 and CDP in vitro resulted in the inability of each protein to bind to DNA in gel retardation assays. CDP overexpression in cultured T cells led to a loss of detectable SATB1 binding to the MMTV promoter region, as measured by gel shift experiments. CDP overexpression also elevated MMTV long terminal repeat reporter gene activity in transient-transfection assays, a result consistent with neutralization of the SATB1 repressor function in T cells. SATB1 is very abundant in certain tissues, particularly thymus, whereas CDP is relatively ubiquitous, except in certain terminally differentiated cell types. Because of the tissue and cell type distribution of SATB1 and CDP, we propose that the SATB1-to-CDP ratio in different tissues is a novel mechanism for homeoproteins to control gene expression and differentiation in mammals.

MR image segmentation and tissue metabolite contrast in 1H spectroscopic imaging of normal and aging brain

The impact of image segmentation on 0.84-ml nominal voxel volume proton spectroscopic imaging in normal brain and in age-related cortical atrophy was investigated. Segmentation improved the gray matter-white matter (GM-WM) contrast for N-acetyl aspartate (NAA)/creatine (Cr) and choline (Cho)/Cr in normal brain, and for NAA/Cho and NAA/Cr in atrophic brain. NAA(GM/WM) (approximately 0.7), Cho(GM/WM) (approximately 0.8), and Cr(GM/WM) (approximately 1.3) in normal brain obtained with segmentation agreed with values obtained with quantitative magnetic resonance spectroscopy. Age-related cortical atrophy led to decreased cortical GM NAA/Cho and NAA/Cr; no changes were evident in WM or in NAA(GM/WM), Cho(GM/WM), or Cr(GM/WM). GM/WM metabolite analysis may be of limited use in conditions in which parallel metabolite changes occur in WM and GM.

Simultaneous rupturing heterotopic pregnancy and acute appendicitis in an in-vitro fertilization twin pregnancy

The presentation of acute abdominal pain in young women is not an unusual occurrence in casualty and gynaecology departments. Both acute appendicitis and ectopic pregnancy have to be considered and investigated, as these two conditions are accepted as the most common surgical causes of an acute abdomen. Difficulties in correctly identifying the cause of the pain can be hazardous to the patient and care needs to be taken in obtaining a prompt and accurate diagnosis enabling the most appropriate management. The case report presented here describes the extremely unusual occurrence of both these acute conditions happening simultaneously with the added complication of an ongoing twin pregnancy and it highlights the need to look beyond the most obvious diagnosis and always to expect the unexpected.

Acute deleterious effects of cocaine on cardiac conduction, hemodynamics, and ventricular fibrillation threshold: effects of interaction with a selective dopamine D1 antagonist SCH 39166

Cocaine has demonstrated cardiotoxicity that has led to sudden death by unknown mechanisms. SCH 39166, a selective dopaminergic D1-receptor antagonist, suppresses the compulsive drug-intake actions of cocaine in primates. This study examined the cumulative toxic effects of cocaine after the long-term administration of SCH 39166. After pretreatment with oral placebo/SCH 39166 for 5 days, an i.v. infusion of 0.25 mg/kg/min of cocaine HCl was delivered to 14 anesthetized dogs, and cardiac conduction, arterial blood pressure, ventricular refractoriness, and arrhythmogenesis were examined. The cocaine infusion was stopped when QRS width increased by 20% from baseline (QRS20). In Coc + Placebo regimen, the QRS and His-Ventricular (HV) intervals showed a dose-dependent lengthening. Initially, the mean blood pressure (MBP) increased followed by a precipitate decrease at a mean dose of 2.03 +/- 0.5 mg/kg of cocaine. At QRS20, the ventricular effective refractory period (ERP) increased significantly, whereas the ventricular fibrillation threshold (VFT) showed a significant reduction from the baseline. In Coc + SCH, the QRS, HV intervals, and ERP increased similarly, but the decrease in MBP was attenuated, and the VFT was increased. A relatively small infusion of cocaine causes a hemodynamic compromise. The His-ventricular conduction delay and lengthened ERP suggest a predominant direct local anesthetic effect. Cocaine additionally decreased the VFT, suggesting an increased susceptibility to VF. SCH 39166 did not potentiate the cardiotoxic effects of cocaine. It displayed a protective trend by suppressing the arrhythmogenic effects and the hemodynamic compromise caused by cocaine.

Cluster randomization: a trap for the unwary

Controlled trials that randomize by practice can provide robust evidence to inform patient care. However, compared with randomizing by each individual patient, this approach may have substantial implications for sample size calculations and the interpretation of results. An increased awareness of these effects will improve the quality of research based on randomization by practice.

Anxiety and depression in mothers related to severe malformation of the heart of the child and foetus

The aim of the study was to assess levels of anxiety and depression in three groups: pregnant mothers referred to foetal cardiology, subdivided into those with a confirmed diagnosis and those for which no abnormality was detected, and mothers who had a child with a heart malformation. Psychological status was measured between 6 and 10 months after diagnosis using the Hospital Anxiety and Depression scale in 108 females. Levels of anxiety were higher in the two groups with a confirmed diagnosis in the antenatal period or after birth (62%) than in those who were screened positively but in whom no abnormality was found (30%) (p = 0.0055). Anxiety was the highest in young females who had a foetus with a heart malformation. Depression scores were higher in those who had a child with heart malformation (18%) than in the other two groups (5%). Mothers who terminated a pregnancy after diagnosis remained depressed long after the event. Younger mothers may be especially vulnerable to mood problems associated with a traumatic obstetric experience.

Evidence by allelic association-dependent methods for a type 1 diabetes polygene (IDDM6) on chromosome 18q21

Type 1 diabetes is a common polygenic disease. Fine mapping of polygenes by affected sibpair linkage analysis is not practical and allelic association or linkage disequilibrium mapping will have to be employed to attempt to detect founder chromosomes. Given prior evidence of linkage of the Jk-D18S64 region of chromosome 18q12-q21 to type 1 diabetes, we evaluated the 12 informative microsatellite markers in the region for linkage with disease by the transmission disequilibrium test (TDT) in a UK data set of type 1 diabetic families (n = 195). Increased transmission of allele 4 of marker D18S487 to affected children was detected (P = 0.02). Support for this was extended in a total of 1067 families from four different countries by isolating, and evaluating by the TDT, two novel microsatellites within 70 kb of D18S487. Evidence for linkage and association was P = 5 x 10(-5) and 3 x 10(-4), respectively. There was no evidence for increased transmission of associated alleles to nonaffected siblings. Analysis of an additional 390 families by the TDT did not extend the evidence further, and reduced support in the total 1457 families to P = 0.001 for linkage and P = 0.003 for association. However, evidence for linkage by affected sibpair allele sharing was strong (P = 3.2 x 10(-5)) in the second data set. Heterogeneity in TDT results between data sets was, in part, accounted for by the presence of more than one common disease-associated haplotype (allelic heterogeneity) which confounds the analysis of individual alleles by the TDT. Guidelines for strategies for the mapping of polygenes are suggested with the emphasis on collections of large numbers of families from multiple populations that should be as genetically homogeneous as possible.

The molecular basis of the Kidd blood group polymorphism and its lack of association with type 1 diabetes susceptibility

The Kidd blood group locus encodes a urea transporter which is expressed on human red cells and in the kidney. This gene is located on chromosome 18q12, and evidence for linkage and association with type 1 diabetes mellitus has been reported. To investigate this further, the genetic basis for the blood group Jk(a)/Jk(b) polymorphism was first determined by sequencing reverse-transcribed reticulocyte RNAs from Jk(a+b-) and Jk(a-b+) donors. The Jk(a)/Jk(b) polymorphism was caused by a transition (G838A), resulting in a Asp280Asn amino acid substitution and an MnlI restriction fragment length polymorphism (RFLP). Using the MnlI RFLP, we found that the Jk(a)/Jk(b) polymorphism was not in linkage disequilibrium with type 1 diabetes in 228 multiplex UK and US families tested.

Evidence for a type 1 diabetes susceptibility locus (IDDM10) on human chromosome 10p11-q11

A region of linkage to type 1 diabetes has been defined on human chromosome 10p11-q11 (IDDM10; P = 0.0007) using 236 UK and 76 US affected sibpairs and a 1 cM resolution microsatellite marker map. Analysis by the transmission disequilibrium test (TDT) in 1159 families with at least one diabetic child, from the UK, the US, Norway, Sardinia and Italy provided additional support for linkage at D10S193 (P = 0.006, Pc = 0.17). Notably, 5.1 cM distal to D10S193, marker D10S588 also provided positive TDT results (P = 0.009, Pc = 0.25) but the allele under analysis was also preferentially transmitted to nonaffected siblings (P = 0.0008, Pc = 0.02). This allele was positively associated in an independent UK case control study and, importantly, was neutrally transmitted in control CEPH families. These results suggest a type 1 diabetes susceptibility locus on chromosome 10p11-q11 (provisionally designated IDDM10) and demonstrate the necessity of analysis of non affected siblings in disease families, as well as analysis of control families.

Diffusion tensor MR imaging of the human brain

PURPOSE

To assess intrinsic properties of water diffusion in normal human brain by using quantitative parameters derived from the diffusion tensor, D, which are insensitive to patient orientation.

MATERIALS AND METHODS

Maps of the principal diffusivities of D, of Trace(D), and of diffusion anisotropy indices were calculated in eight healthy adults from 31 multisection, interleaved echo-planar diffusion-weighted images acquired in about 25 minutes.

RESULTS

No statistically significant differences in Trace(D) (approximately 2,100 x 10(-6) mm2/sec) were found within normal brain parenchyma, except in the cortex, where Trace(D) was higher. Diffusion anisotropy varied widely among different white matter regions, reflecting differences in fiber-tract architecture. In the corpus callosum and pyramidal tracts, the ratio of parallel to perpendicular diffusivities was approximately threefold higher than previously reported, and diffusion appeared cylindrically symmetric. However, in other white matter regions, particularly in the centrum semiovale, diffusion anisotropy was low, and cylindrical symmetry was not observed. Maps of parameters derived from D were also used to segment tissues based on their diffusion properties.

CONCLUSION

A quantitative characterization of water diffusion in anisotropic, heterogeneously oriented tissues is clinically feasible. This should improve the neuroradiologic assessment of a variety of gray and white matter disorders.

High temporal resolution diffusion MRI of global cerebral ischemia and reperfusion

Although brain ischemia has been extensively studied using diffusion-weighted magnetic resonance imaging, most studies performed so far have not had adequate time resolution to follow the temporal changes in the water apparent diffusion coefficient (ADC) in hyperacute ischemia. Using diffusion echo planar imaging, we obtained ADC maps (calculated from measurements made with 8 b-values) with a time resolution of 43 s in a feline model of global brain ischemia and reperfusion. Different protocols were performed: 10-min hypoperfusion, 10- and 22-min ischemia followed by reperfusion, and cardiac arrest. ADC values were obtained from white matter of the internal capsule and from the thalamus. Cortical gray matter measurements were not deemed reliable due to the close proximity of CSF in the cortical sulci. Following occlusion, the ADC declined in the thalamus to < 2 SD of its normal baseline value within 1.5-2.5 min. This decay was exponential with a time constant (tau +/- SD) of 6.0 +/- 2.6 min; no further decrease in the ADC was observed 10 min following ischemia. Following reperfusion, in animals that showed ADC recovery, the ADC began increasing immediately, returning to its preischemic value in approximately 15 min. No significant ADC changes were observed during hypoperfusion. Following cardiac arrest, the decay of ADC was more rapid in the thalamus (tau = 2.6 +/- 0.6 min) than in white matter (tau = 6.6 +/- 1.8 min). We observed that the ADC at 40 min after cardiac arrest was similar to the ADC at 10 min after ischemia. Given that all animals subjected to 10-min ischemic episodes showed ADC recovery with reperfusion, doubt is cast on whether it is possible to define a threshold value of the ADC below which brain tissue is irreversibly damaged. Finally, despite variability in the time constants of the ADC decay induced by ischemia, the ADC values at 10 min were very similar in all the animals. This suggests that when blood flow is diminished sufficiently to induce an ADC reduction, differences in perfusion affect the rapidity of the decrease but not the final asymptotic value reached.

Peak oxygen uptake of 12-18-year-old boys living in a densely populated urban environment

The purposes of this study were to provide data on the peak VO2 of 12-18-year-old boys from Hong Kong, a densely populated urban environment; to compare these data with those for other similarly aged populations; and to examine the correlations between peak VO2 and various anthropometric parameters of this group. A stratified, random sample of 86 ethnic Chinese boys had their peak VO2 determined using an on-line gas analysis system during incremental, treadmill running. The mean peak VO2 of the boys was 2.7 SD 0.44 l.min-1 or, when expressed in relation to body mass, 52.0 SD 5.8 ml.kg-1.min-1. Peak VO2 (l.min-1) was significantly correlated with body mass (r = 0.72, p < 0.001, age (r = 0.49, p < 0.001) and height (r = 0.71, p = 0.001). Peak VO2 (ml.kg-1.min-1) showed no correlation with age or height. These data suggest that this population group has peak VO2 values very similar to those observed in boys from most other population groups.

Effectiveness of doxycycline combined with primaquine for malaria prophylaxis

OBJECTIVE

To assess the causal prophylactic activity (activity against the pre-erythrocytic liver stage) of a daily regimen of doxycycline combined with low dose primaquine against malaria in Australian Defence Force personnel deployed to Papua New Guinea (PNG).

PARTICIPANTS AND SETTING

A 53-strong Australian Army engineer detachment deployed to the north coast of PNG for 42 days starting in July 1993.

INTERVENTIONS

The soldiers took doxycycline (100 mg) and primaquine (7.5 mg) daily, starting at least two days before they entered the endemic area and continuing for three days after their return to Australia. No primaquine eradication course was given at that time.

MAIN OUTCOME MEASURES

The number of soldiers who developed malaria, plasma drug concentrations and drug side effects.

RESULTS

None of the 53 men developed malaria while in PNG. Three developed falciparum malaria two to three weeks after leaving the endemic area, although one of them had taken doxycycline alone because of glucose-6-phosphate dehydrogenase deficiency. Nine men developed vivax malaria between three and 40 weeks after leaving PNG, and three had relapses. Doxycycline was generally well tolerated, with only three of the men requiring a change of medication to mefloquine because of adverse gastrointestinal symptoms.

CONCLUSIONS

Although doxycycline generally provides good protection against malaria infection, it cannot be relied on for causal prophylaxis, even when combined with low dose primaquine. Because the malaria infections occurred only after return to Australia, doxycycline appears to be effective in suppressing malaria while the drug is being taken. Intense, repeated exposure to malaria may require an extended period of chemoprophylaxis on return from an endemic area.