Sex Differences in the Catecholamine Output of Children

Urinary excretion of catecholamines was studied in 240 normal, healthy children 12 years of age during a passive condition (film exposure) and an active condition (arithmetic test) at school. No sex differences in catecholamine excretion were found during the passive condition, whereas, during the work period, boys excreted significantly more adrenaline and noradrealine than girls. A comparison is made between catecholamine excretion levels of the children and adult subjects examined in other studies.     

Mice with mutations in Mahogunin ring finger-1 (Mgrn1) exhibit abnormal patterning of the left-right axis.

Mahogunin Ring Finger 1 (Mgrn1) encodes a RING-containing protein with ubiquitin ligase activity that has been implicated in pigment-type switching. In addition to having dark fur, mice lacking MGRN1 develop adult-onset spongy degeneration of the central nervous system and have reduced embryonic viability. Observation of complete situs inversus in a small proportion of adult Mgrn1 mutant mice suggested that embryonic lethality resulted from congenital heart defects due to defective establishment and/or maintenance of the left-right (LR) axis. Here we report that Mgrn1 is expressed in a pattern consistent with a role in LR patterning during early development and that many Mgrn1 mutant embryos show abnormal expression of asymmetrically expressed genes involved in LR patterning. A range of complex heart defects was observed in 20-25% of mid-to-late gestation Mgrn1 mutant embryos and another 20% were dead. This finding was consistent with 46-60% mortality of mutants by weaning age. Our results indicate that Mgrn1 acts early in the LR signaling cascade and is likely to provide new insight into this developmental process as Nodal expression was uncoupled from expression of other Nodal-responsive genes in Mgrn1 mutant embryos. Our work identifies a novel role for MGRN1 in embryonic patterning and suggests that the ubiquitination of MGRN1 target genes is essential for the proper establishment and/or maintenance of the LR axis.     

Partner acceptance of health department notification of HIV exposure, South Carolina

To determine the acceptability of health department notification of sex and needle-sharing partners of persons infected with human immunodeficiency virus (HIV), we administered an anonymous questionnaire to partners notified of their exposure to HIV during the previous 2 years. Of the 202 partners notified, 132 (65%) were locatable and completed the questionnaire. Only 12 (9%) thought they may have been exposed to HIV before health department notification. When the 132 partners were asked if they thought the health department did the right thing in telling them about their exposure, 87% responded "yes;" when asked if the health department should keep notifying persons exposed to HIV, 92% responded "yes." Responses were similar for homosexual-bisexual men, heterosexuals, and intravenous drug users; men and women; and whites and blacks. We conclude that health department notification is acceptable to persons exposed to HIV in this rural South Carolina district.     

Calcium absorption and kinetics are similar in 7- and 8-year-old Mexican-American and Caucasian girls despite hormonal differences

To assess the possibility of ethnic differences in mineral metabolism in prepubertal children, we compared measures of calcium metabolism in 7- and 8-y-old Mexican-American (MA) and non-Hispanic Caucasian (CAU) girls (n = 38) living in southeastern Texas. We found similar fractional calcium absorption, urinary calcium excretion, calcium kinetic values and total-body bone mineral content in the MA and CAU girls. In contrast, parathyroid hormone (PTH) concentrations were greater in MA girls (4.01 +/- 0.47 vs. 1. 96 +/- 0.50 pmol/L, P = 0.005) than in CAU girls. Serum 25-hydroxyvitamin D concentrations were lower in MA girls (68.9 +/- 7.7 vs. 109.4 +/- 8.4 nmol/L, P = 0.001) than in CAU girls, but 1, 25-dihydroxyvitamin D concentrations did not differ between groups. Seasonal variability was seen for 25-hydroxyvitamin D concentrations in girls of both ethnic groups, but values in all of the girls were >30 nmol/L (12 ng/mL). We conclude the following: 1) greater PTH levels in MA girls than CAU girls are present without evidence of vitamin D deficiency; and 2) differences in 25-hydroxyvitamin D and PTH concentrations between MA and CAU girls do not have a large effect on calcium absorption, excretion or bone calcium kinetics. These data do not provide evidence for adjusting dietary recommendations for mineral or vitamin D intake by MA girls.     

The effect of asphyxia on superior mesenteric artery blood flow in the premature sheep fetus

BACKGROUND/PURPOSE: The aim of this study was to determine superior mesenteric artery blood flow changes during and after an asphyxial insult in utero in chronically instrumented unanaesthetised premature fetal sheep. METHODS: Fetal sheep at 0.7 gestation (103 to 104 days) underwent 25 minutes of complete umbilical cord occlusion (n = 6) or sham occlusion (n = 6). Fetal heart rate, blood pressure, superior mesenteric artery (SMA) blood flow and vascular resistance, electroencephalographic activity, and nuchal electromyographic activity were measured from 6 hours before occlusion until 3 days after occlusion. Fetal gastrointestinal tissue was taken for histological assessment. RESULTS: During occlusion, cardiovascular response was characterised by 3 phases: initial redistribution of blood flow away from the gut to maintain vital organ function, subsequently partial failure of this redistribution, and finally near terminal cardiovascular collapse with profound hypotension and gastrointestinal hypoperfusion. Postasphyxia there was a secondary period of hypoperfusion that was mediated by increased vascular resistance, not hypotension. There was no evidence of injury on standard histological assessment after 3 days of recovery. CONCLUSIONS: SMA blood flow is not only significantly reduced during asphyxia, but also for several hours after an asphyxial insult. The authors speculate that these perturbations of gastrointestinal blood flow could compromise gut wall integrity potentially leading to increased vulnerability to necrotising enterocolitis.     

Validation of a clinical decision rule: chest X-ray in patients with chest pain and possible acute coronary syndrome

Current literature suggests that a large proportion of chest X-rays (CXRs) performed in emergency department (ED) patients with chest pain and suspected acute coronary syndrome (ACS) are unnecessary. The Canadian ACS Guidelines aim to guide clinicians in the appropriate use of CXR within this patient population. This study determined the prevalence of clinically significant CXR abnormalities and assessed the utility of the guidelines in a population of ED patients with chest pain and suspected ACS. Included in the study were participants over the age of 18 who presented to an Australian metropolitan ED, over a 1-year period, with a primary complaint of chest pain and who had a CXR and troponin level ordered in the ED (N?=?760). We retrospectively compared their radiographic findings with their recommendations for CXR according to the ACS Guidelines. We found that 12 % of the participants had a clinically significant chest X-ray. The guidelines had a sensitivity of 80 % (95 % CI 0.70–0.87) and specificity of 50 % (95 % CI 0.47–0.54). The positive predictive value was 18 % (95 % CI 0.15–0.22) with a 95 % negative predictive value (95 % CI 0.92–0.97). Had the ACS guidelines been applied to our patient population, the number of CXR performed would have been reduced by 47 %. This study suggests that the ACS Guidelines has the potential to reduce the numbers of unnecessary CXR performed in ED patients. However, this would come at the expense of missing a minority of significant CXR abnormalities.