Factors Associated With Changes in Magnesium Levels in Asymptomatic Neonates: A Longitudinal Analysis

Background: Neonates and infants with hypomagnesemia present with seizures and psychomotor delay. Objectives: The present study evaluated the changes in magnesium (Mg) levels and factors associated with these in the first three days of life. Materials and Methods: We monitored 50 clinically asymptomatic neonates; they were not given any magnesium supplements even if they had hypomagnesemia at baseline. The variables analysed were: serum Mg; gestational age; birth weight; length; and the ponderal index. We used random effects (RE) models for longitudinal analysis of these data. Results: The mean standard deviation (SD) gestational age was 36.3 (3.6) weeks and the mean (SD) weight was 2604.2 (754.4) grams. About 31% of the neonates had hypomagnesemia (< 1.6 mg/dL) on day one; however, all had normal magnesium levels by day three of life (P < 0.001). At birth, after adjusting for intrauterine growth retardation status (IUGR), serum Mg levels were lower by 0.0097 mg/dL (95% CI: -0.019 to -0.0003) per 100 grams increase in weight of the neonate. After adjusting for IUGR status, the mean increase in the serum Mg levels was 0.14 mg/dL (95% confidence intervals [CI]: 0.10 to 0.18) per day. The per-day increase in magnesium levels was significantly higher in low birth weight babies (0.10, 95% CI: 0.01 to 0.18) compared with normal birth weight babies. Conclusions: Asymptomatic neonates may have a high prevalence of hypomagnesemia; however, the levels become normal without any magnesium supplementation. Even though regular monitoring of magnesium levels is useful, no supplements are required - particularly in clinically asymptomatic neonates.

The role of inflammation in vascular function and pregnancy outcome in the pregnant stroke prone spontaneously hypertensive rat

During pregnancy, the maternal cardiovascular system undergoes major adaptation. One of these changes is a 40-50 % increase in circulating blood volume which requires a systemic remodelling of the vasculature in order to regulate maternal blood pressure and maximise blood supply to the developing placenta and fetus. These changes are broadly conserved between humans and rats making them an appropriate pre-clinical model in which to study the underlying mechanisms of pregnancy-dependent cardiovascular remodelling. Whilst women are normally protected against cardiovascular disease; pregnancy marks a period of time where women are susceptible to cardiovascular complications. Cardiovascular disease is the leading cause of maternal mortality in the United Kingdom; in particular hypertensive conditions are among the most common complications of pregnancy. One of the main underlying pathologies of these pregnancy complications is thought to be a failure of the maternal cardiovascular system to adapt. The remodelling of the uterine arteries, which directly supply the maternal-fetal interface, is paramount to a healthy pregnancy. Failure of the uterine arteries to remodel sufficiently can result in a number of obstetric complications such as preeclampsia, fetal growth restriction and spontaneous pregnancy loss. At present, it is poorly understood whether this deficient vascular response is due to a predisposition from existing maternal cardiovascular risk factors, the physiological changes that occur during pregnancy or a combination of both. Previous work in our group employed the stroke prone spontaneously hypertensive rat (SHRSP) as a model to investigate pregnancy-dependent remodelling of the uterine arteries. The SHRSP develops hypertension from 6 weeks of age and can be contrasted with the control strain, the Wistar Kyoto (WKY) rat. The phenotype of the SHRSP is therefore reflective of the clinical situation of maternal chronic hypertension during pregnancy. We showed that the SHRSP exhibited a deficient uterine artery remodelling response with respect to both structure and function accompanied by a reduction in litter size relative to the WKY at gestational day (GD) 18. A previous intervention study using nifedipine in the SHRSP achieved successful blood pressure reduction from 6 weeks of age and throughout pregnancy; however uterine artery remodelling and litter size at GD18 was not improved. We concluded that the abnormal uterine artery remodelling present in the SHRSP was independent of chronic hypertension. From these findings, we hypothesised that the SHRSP could be a novel model of spontaneously deficient uterine artery remodelling in response to pregnancy which was underpinned by other as yet unidentified cardiovascular risk factors. In Chapter 1 of this thesis, I have characterised the maternal, placental and fetal phenotype in pregnant (GD18) SHRSP and WKY. The pregnant SHRSP exhibit features of left ventricular hypertrophy in response to pregnancy and altered expression of maternal plasma biomarkers which have been previously associated with hypertension in human pregnancy. I developed a protocol for accurate dissection of the rat uteroplacental unit using qPCR probes specific for each layer. This allowed me to make an accurate and specific statement about gene expression in the SHRSP GD18 placenta; where oxidative stress related gene markers were increased in the vascular compartments. The majority of SHRSP placenta presented at GD18 with a blackened ring which encircled the tissue. Further investigation of the placenta using western blot for caspase 3 cleavage determined that this was likely due to increased cell death in the SHRSP placenta. The SHRSP also presented with a loss of one particular placental cell type at GD18: the glycogen cells. These cells could have been the target of cell death in the SHRSP placenta or were utilised early in pregnancy as a source of energy due to the deficient uterine artery blood supply. Blastocyst implantation was not altered but resorption rate was increased between SHRSP and WKY; indicating that the reduction in litter size in the SHRSP was primarily due to late (>GD14) pregnancy loss. Fetal growth was not restricted in SHRSP which led to the conclusion that SHRSP sacrifice part of their litter to deliver a smaller number of healthier pups. Activation of the immune system is a common pathway that has been implicated in the development of both hypertension and adverse pregnancy outcome. In Chapter 2, I proposed that this may be a mechanism of interest in SHRSP pregnancy and measured the pro-inflammatory cytokine, TNFα, as a marker of inflammation in pregnant SHRSP and WKY and in the placentas from these animals. TNFα was up-regulated in maternal plasma and urine from the GD18 SHRSP. In addition, TNFα release was increased from the GD18 SHRSP placenta as was the expression of the pro-inflammatory TNFα receptor 1 (Tnfr1). In order to investigate whether this excess TNFα was detrimental to SHRSP pregnancy, a vehicle-controlled intervention study using etanercept (a monoclonal antibody which works as a TNFα antagonist) was carried out. Etanercept treatment at GD0, 6, 12 and 18 resulted in an improvement in pregnancy outcome in the SHRSP with an increased litter size and reduced resorption rate. Furthermore, there was an improved uterine artery function in GD18 SHRSP treated with etanercept which was associated with an improved uterine artery blood flow over the course of gestation. In Chapter 3, I sought to identify the source of this detrimental excess of TNFα by designing a panel for maternal leukocytes in the blood and placenta at GD18. A population of CD3- CD161+ cells, which are defined as rat natural killer (NK) cells, were increased in number in the SHRSP. Intracellular flow cytometry also identified this cell type as a source of excess TNFα in blood and placenta from pregnant SHRSP. I then went on to evaluate the effects of etanercept treatment on these CD3- CD161+ cells and showed that etanercept reduced the expression of CD161 and the cytotoxic molecule, granzyme B, in the NK cells. Thus, etanercept limits the cytotoxicity and potential damaging effect of these NK cells in the SHRSP placenta. Analysing the urinary peptidome has clinical potential to identify novel pathways involved with disease and/or to develop biomarker panels to aid and stratify diagnosis. In Chapter 4, I utilised the SHRSP as a pre-clinical model to identify novel urinary peptides associated with hypertensive pregnancy. Firstly, a characterisation study was carried out in the kidney of the WKY and SHRSP. Urine samples from WKY and SHRSP taken at pre-pregnancy, mid-pregnancy (GD12) and late pregnancy (GD18) were used in the peptidomic screen. In order to capture peptides which were markers of hypertensive pregnancy from the urinary peptidomic data, I focussed on those that were only changed in a strain dependent manner at GD12 and 18 and not pre-pregnancy. Peptide fragments from the uromodulin protein were identified from this analysis to be increased in pregnant SHRSP relative to pregnant WKY. This increase in uromodulin was validated at the SHRSP kidney level using qPCR. Uromodulin has previously been identified to be a candidate molecule involved in systemic arterial hypertension but not in hypertensive pregnancy thus is a promising target for further study. In summary, we have characterised the SHRSP as the first model of maternal chronic hypertension during pregnancy and identified that inflammation mediated by TNFα and NK cells plays a key role in the pathology. The evidence presented in this thesis establishes the SHRSP as a pre-clinical model for pregnancy research and can be continued into clinical studies in pregnant women with chronic hypertension which remains an area of unmet research need.

In utero protein restriction causes growth delay and alters sperm parameters in adult male rats

Background: Recent studies have supported the concept of ""fetal programming"" which suggests that during the intrauterine development the fetus may be programmed to develop diseases in adulthood. The possible effects of in utero protein restriction on sexual development of rat male offspring were evaluated in the present study. Methods: Pregnant Wistar rats were divided into two experimental groups: one group treated with standard chow (SC, n = 8, 17% protein) and the other group treated with hypoproteic chow (HC, n = 10, 6% protein) throughout gestation. After gestation the two experimental groups received standard chow. To evaluate the possible late reproductive effects of in utero protein restriction, the male offspring of both groups were assessed at different phases of sexual development: prepubertal (30 days old); peripubertal (60 days old); adult (90 days old). Student's t test and Mann-Whitney test were utilized. Differences were considered significant when p < 0.05. Results: We found that in utero protein restriction reduced the body weight of male pups on the first postnatal day and during the different sexual development phases (prepubertal, peripubertal and adult). During adulthood, Sertoli cell number, sperm motility and sperm counts in the testis and epididymal cauda were also reduced in HC. Furthermore, the numbers of sperm presenting morphological abnormalities and cytoplasmic drop retention were higher in HC. Conclusions: In conclusion, in utero protein restriction, under these experimental conditions, causes growth delay and alters male reproductive-system programming in rats, suggesting impairment of sperm quality in adulthood.

In utero protein restriction causes growth delay and alters sperm parameters in adult male rats

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Perinatal salt restriction: A new pathway to programming adiposity indices in adult female Wistar rats

Low birth weight has been associated with increased obesity in adulthood. It has been shown that dietary salt restriction during intrauterine life induces low birth weight and insulin resistance in adult Wistar rats. The present study had a two-fold objective: to evaluate the effects that low salt intake during pregnancy and lactation has on the amount and distribution of adipose tissue; and to determine whether the phenotypic changes in fat mass in this model are associated with alterations in the activity of the renin-angiotensin system. Maternal salt restriction was found to reduce birth weight in male and female offspring. In adulthood, the female offspring of dams fed the low-salt diet presented higher adiposity indices than those seen in the offspring of dams fed a normal-salt diet. This was attributed to the fact that adipose tissue mass (retroperitoneal but not gonadal, mesenteric or inguinal) was greater in those rats than in the offspring of dams fed a normal diet. The adult offspring of dams fed the low-salt diet, compared to those dams fed a normal-salt diet, presented the following: plasma leptin levels higher in males and lower in females; plasma renin activity higher in males but not in females; and no differences in body weight, mean arterial blood pressure or serum angiotensin-converting enzyme activity. Therefore, low salt intake during pregnancy might lead to the programming of obesity in adult female offspring. (c) 2009 Elsevier Inc. All rights reserved.

Influence of early quantitative food restriction on long bone growth at different environmental temperatures in broiler chickens

1. This investigation was carried out to study the influence of early quantitative food restriction (40% of ad libitum intake from 7 to 14 d of age) and environmental rearing temperature (thermoneutral, cold and hot) on long bone (tibia, femur and humerus) development in broiler chickens.2. Tibia, femur and humerus were obtained at the ages of 14, 21, 28, 35 and 42 d; and the variables studied were: length and width (mm, expressed as absolute values), bone breaking strength (kgf) and bone weight/bone length index (BW/BL, mg/mm).3. All bone variables increased with bird age. Food restriction reduced bone length and width but did not affect bone weight. High environmental rearing temperature reduced bone length and width at 42 d of age. Bone strength was not affected by environmental temperature but the calculated BW/BL index was reduced by heat exposure.4. The findings suggest that food restriction and high environmental rearing temperature reduce long bone growth; bone breaking strength was affected by bird age but not by food restriction nor rearing ambient temperature.

Implications of intrauterine protein malnutrition on prostate growth, maturation and aging

Aims Maternal malnutrition by low protein diet is associated with an increased incidence of metabolic disorders and decreased male fertility in adult life. This study aimed to assess the impact of maternal protein malnutrition (MPM) on prostate growth, tissue organization and lesion incidence with aging. Main methods Wistar rat dams were distributed into two groups, which were control (NP; fed a normal diet containing 17% protein) or a restricted protein diet (RP, fed a diet containing 6% protein) during gestation. After delivery all mothers and offspring received a normal diet. Biometrical parameters, hormonal levels and prostates were harvested at post-natal days (PND) 30, 120 and 360. Key findings MPM promoted low birth weight, decreased ano-genital distance (AGD) and reduced androgen plasma levels of male pups. Prostatic lobes from RP groups presented reduced glandular weight, epithelial cell height and alveolar diameter. The epithelial cell proliferation and collagen deposition were increased in RP group. Incidences of epithelial dysplasia and prostatitis were higher in the RP offspring than in the NP offspring at PND360. Significance Our findings show that MPM delays prostate development, growth and maturation until adulthood, probably as a result of low testosterone stimuli. The higher incidence of cellular dysplasia and prostatitis suggests that MPM increases prostate susceptibility to diseases with aging. © 2013 Elsevier Inc.

Short periods of food restriction do not affect growth, survival or muscle development on pacu larvae

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Protein restriction inhibits gastric cell proliferation during rat postnatal growth in parallel to ghrelin changes

Objective: Gastric development depends directly on the proliferation and differentiation of epithelial cells, and these processes are controlled by multiple elements, such as diet, hormones, and growth factors. Protein restriction affects gastrointestinal functions, but its effects on gastric growth are not fully understood. Methods: The present study evaluated cell proliferation in the gastric epithelia of rats subjected to protein restriction since gestation. Because ghrelin is increasingly expressed from the fetal to the weaning stages and might be part of growth regulation, its distribution in the stomach of rats was investigated at 14, 30, and 50 d old. Results: Although the protein restriction at 8% increased the intake of food and body weight, the body mass was lower (P < 0.05). The stomach and intestine were also smaller but increased proportionately throughout treatment. Cell proliferation was estimated through DNA synthesis and metaphase indices, and lower rates (P < 0.05) were detected at the different ages. The inhibition was concomitant with a larger number of ghrelin-immunolabeled cells at 30 and 50 d postnatally. Conclusion: Protein restriction impairs cell proliferation in the gastric epithelium, and a ghrelin upsurge under this condition is parallel to lower gastric and body growth rates. (C) 2012 Elsevier Inc. All rights reserved.

Defining Fluid Restriction in the Management of Infants Following Cardiac Surgery and Understanding the Subsequent Impact on Nutrient Delivery and Growth Outcomes

Adequacy of nutritional intake during the postoperative period, as measured by a change in weight-for-age z-scores from surgery to the time of discharge, was evaluated in infants (n = 58) diagnosed with a congenital heart defect and admitted for surgical intervention at Miami Children’s Hospital using a prospective observational study design. Parental consent was obtained for all infants who participated in the study. Forty patients had a weight available at hospital discharge. The mean preoperative weight-for-age z-score was -1.3 ±1.43 and the mean weight-for-age z-score at hospital discharge was -1.89 ±1.35 with a mean difference of 0.58 ±0.5 (P Nutritional intake during the postoperative period was inadequate based on a decrease in weight-for-age z-scores from the time of surgery until discharged home. Our findings suggested that limited fluid volume for nutrition likely contributes to suboptimal nutritional delivery during the postoperative period; however, inadequate nutrition prescription may also be an important contributing factor. Development of a nutrition protocol for initiation and advancement of nutrition support may reduce the delay in achieving patient’s nutritional goals and may attenuate the observed decrease in z-scores during the postoperative period.

Effect of maternal cold exposure and nutrient restriction on insulin-like growth factor sensitivity in adipose tissue of newborn sheep

Adipose tissue mass in the newborn is determined in part by insulin-like growth factor (IGF)s, which are dependent on the maternal nutritional and metabolic environment during late gestation. The present study was designed to determine whether maternal cold exposure (CE) commencing in mid gestation could modulate some of the adaptive effects of nutrient restriction in late gestation on adipose tissue endocrine sensitivity in the resulting offspring. Twenty eight pregnant sheep were entered into the study and were either shorn, i.e. cold exposed, from 70 days gestation (term = 147 days), or remained unshorn, and were fed either their total calculated metabolisable energy (ME) requirements for body weight and pregnancy from 110 days gestation or 50% of this amount (n=7 per group). Adipose tissue was sampled from the offspring at one day of age and the mRNA abundance for IGF-I, II their receptors (R) and GH secretagogue receptor-1a (GHSR-1a) were determined. CE mothers produced larger offspring with more perirenal adipose tissue, an adaptation prevented by maternal nutrient restriction. Nutrient restriction in unshorn mothers increased IGF-I and IIR mRNA abundance. The mRNA abundances for IGF-I, II and IIR in adipose tissue were reduced by CE, adaptations independent of maternal food intake, whereas CE plus nutrient restriction increased GHSR-1a mRNA. In conclusion, maternal nutrient restriction with or without CE has very different effects on IGF sensitivity of adipose tissue and may act to ensure adequate fat stores are present in the newborn in the face of very different maternal endocrine and metabolic environments.

Defining fluid restriction in the management of infants following cardiac surgery and understanding the subsequent impact on nutrient delivery and growth outcomes

Adequacy of nutritional intake during the postoperative period, as measured by a change in weight-for-age z-scores from surgery to the time of discharge, was evaluated in infants (n = 58) diagnosed with a congenital heart defect and admitted for surgical intervention at Miami Children’s Hospital using a prospective observational study design. Parental consent was obtained for all infants who participated in the study. ^ Forty patients had a weight available at hospital discharge. The mean preoperative weight-for-age z-score was -1.3 ±1.43 and the mean weight-for-age z-score at hospital discharge was -1.89 ±1.35 with a mean difference of 0.58 ±0.5 (P = 0.2).^ Nutritional intake during the postoperative period was inadequate based on a decrease in weight-for-age z-scores from the time of surgery until discharged home. Our findings suggested that limited fluid volume for nutrition likely contributes to suboptimal nutritional delivery during the postoperative period; however, inadequate nutrition prescription may also be an important contributing factor. Development of a nutrition protocol for initiation and advancement of nutrition support may reduce the delay in achieving patient’s nutritional goals and may attenuate the observed decrease in z-scores during the postoperative period.^

Respostas agudas da variabilidade da frequência cardíaca após sesão de exercício de força com restrição de fluxo sanguíneo = : Acute responses of heart rate variabiblity afer blood flow restriction resistance exercise

Universidade Estadual de Campinas . Faculdade de Educação Física

Response of Wolfiporia cocos to iron availability: alterations in growth, expression of cellular proteins, Fe3+-reducing activity and Fe3+-chelators production

Aims: The main objective of this study was to evaluate the behaviour of the brown-rot fungus Wolfiporia cocos under differential iron availability. Methods and Results: W. cocos was grown under three differential iron conditions. Growth, catecholate and hydroxamate production, and mycelial and extracellular Fe3+-reducing activities were determined. Iron starvation slowed fungal growth and accelerated pH decline. Some mycelial proteins of low molecular weight were repressed under iron restriction, whereas others of high molecular weight showed positive iron regulation. Mycelial ferrireductase activity decreased as culture aged, while Fe3+-reducing activity of low molecular reductants constantly increased. Hydroxamates production suffered only limited iron repression, whereas catecholates production showed to be more iron repressible. Conclusions: W. cocos seems to possess more than one type of iron acquisition mechanism; one involving secretion of organic acids and ferrireductases and/or extracellular reductants, and another relying on secretion of catecholates and hydroxamates chelators. Significance and Impact of the Study: This paper is the first to report the kinetic study of brown-rot fungus grown under differential iron availability, and the information provided here contributes to address more traditional problems in protecting wood from brown decay, and also makes a contribution in the general area of the physiology of brown-rot fungi.