Preterm birth has sex-specific effects on autonomic modulation of heart rate variability in adult sheep

INTRODUCTION

Globally, 11% of infants are born preterm. In adulthood, individuals born preterm are at increased risk of cardiovascular morbidity and mortality, but the mechanistic basis of this remains unknown. Clinically overt cardiovascular disease may be preceded by altered cardiac autonomic activity characterised by increased sympathetic activity and/or reduced parasympathetic activity. Thus, altered cardiac autonomic activity in survivors of preterm birth may underlie later cardiovascular risk.

OBJECTIVE

To investigate the impact of gestational age on cardiac autonomic activity in juvenile and adult sheep.

METHODS AND RESULTS

Singleton-bearing ewes were randomised antenatally to spontaneous term birth (TC; n=73) or corticosteroid induced preterm birth (PT; n=60). Cardiac autonomic modulation was assessed using heart rate variability analysis in juvenile and adult offspring. Preterm birth in adult males was associated with altered sympatho-vagal modulation (LFnu: PT 64 ± 4 vs. TC 49 ± 4, p<0.05; LogLF/HF: PT 1.8 ± 0.1 vs. TC 1.5 ± 0.1, p<0.05) and reduced parasympathetic modulation (LogRMSSD: PT 2.9 ± 0.2 vs. TC 3.4 ± 0.1, p<0.05; LogNN50: PT 0.3 ± 0.4 vs. TC 1.6 ± 0.4, p<0.05). Within the range of term birth, each one-day increment in gestational age was associated with a decrement in LFnu in juvenile females and with a decrement in LFnu and LF/HF ratio, but an increment in RMSSD and NN50 in adult females.

CONCLUSIONS

Cardiac autonomic function in adult sheep is affected in a sex-specific manner by gestational age at birth, even within the term range. Altered cardiac autonomic function may contribute to increased later cardiovascular morbidity in those born preterm.

Maternal undernutrition programs tissue-specific epigenetic changes in the glucocorticoid receptor in adult offspring

Epidemiological data indicate that an adverse maternal environment during pregnancy predisposes offspring to metabolic syndrome with increased obesity, and type 2 diabetes. The mechanisms are still unclear although epigenetic modifications are implicated and the hypothalamus is a likely target. We hypothesized that maternal undernutrition (UN) around conception in sheep would lead to epigenetic changes in hypothalamic neurons regulating energy balance in the offspring, up to 5 years after the maternal insult. We found striking evidence of decreased glucocorticoid receptor (GR) promoter methylation, decreased histone lysine 27 trimethylation, and increased histone H3 lysine 9 acetylation in hypothalami from male and female adult offspring of UN mothers. These findings are entirely compatible with the increased GR mRNA and protein observed in the hypothalami. The increased GR predicted the decreased hypothalamic proopiomelanocortin expression and increased obesity that we observed in the 5-year-old adult males. The epigenetic and expression changes in GR were specific to the hypothalamus. Hippocampal GR mRNA and protein were decreased in UN offspring, whereas pituitary GR was altered in a sex-specific manner. In peripheral polymorphonuclear leukocytes there were no changes in GR methylation or protein, indicating that this epigenetic analysis did not predict changes in the brain. Overall, these results suggest that moderate changes in maternal nutrition, around the time of conception, signal life-long and tissue-specific epigenetic alterations in a key gene regulating energy balance in the hypothalamus.

Vulvovaginitis: clinical features, aetiology, and microbiology of the genital tract

AIM

To clarify the contribution of clinical and environmental factors and infection to the aetiology of vulvovaginitis in premenarchal girls, and to determine clinical indicators of an infectious cause.

DESIGN

It was necessary first to define normal vaginal flora. Cases were 50 premenarchal girls > 2 years old with symptoms of vulvovaginitis; 50 controls were recruited from girls in the same age group undergoing minor or elective surgery.

RESULTS

Interview questionnaire showed no difference between cases and controls in regards to hygiene practices, exposure to specific irritants, or history of possible sexual abuse. Normal vaginal flora was similar to that described in previous studies, with the exception of organisms likely to be associated with sexual activity. 80% of cases had no evidence of an infectious cause. In the 10 cases in whom an infectious cause was found, there was significantly more visible discharge and distinct redness of the genital area on examination compared with other cases.

CONCLUSIONS

The findings suggest that vulvovaginitis in this age group is not usually infectious or necessarily related to poor hygiene, specific irritants or sexual abuse, although any of these can present with genital irritation. The possibility of sexual abuse should always be considered when a child presents with genital symptoms, but our data indicate it is not a common contributing factor. Infection is generally associated with vaginal discharge and moderate or severe inflammation.

Role of gastro-oesophageal reflux in infant irritability

Gastro-oesophageal reflux (GOR) disease may cause excessive crying in infants. The role of GOR was evaluated in infant irritability and an attempt was made to define clinical predictors of pathological reflux. Seventy consecutively admitted infants with irritability and presumptive GOR were retrospectively reviewed. All had undergone prolonged oesophageal pH monitoring. Pathological GOR was defined as a fractional reflux time of > or = 10% and was significantly less common in infants under 3 months (one of 24; 4.2%) than in older infants (10 of 46; 21.7%). All infants with pathological GOR presented with frequent vomiting, and 'silent' pathological reflux did not occur. Poor weight gain, feeding refusal, backarching, and sleep disturbance were not significantly associated with pathological GOR. The results suggest that pathological GOR is an unlikely cause of infant irritability under the age of 3 months.