Minipuberty in Male Full-term Neonates Appropriate and Small for Gestational Age and in Preterm Babies: Data from a Single Centre

Objective

The postnatal activation of the hypothalamic-pituitary-gonadal (HPG) axis is usually known as “minipuberty”. There are still open questions about its biological function and significance depending on sex, gestational age (GA) and birth weight (BW) with few available longitudinal data.

Methods

A single-centre, longitudinal study to quantify urinary follicle stimulating hormone (uFSH), luteinizing hormone (uLH) and testosterone (uTs) in male neonates. Neonates were enrolled and stratified into three subgroups: full-term boys appropriate for GA (FT AGA); FT boys with BW ≤3rd centile [FT small for gestational age (SGA)]; and preterm (PT) boys ≤33 weeks of GA. Urinary hormones were correlated to simultaneous auxological parameters, linear growth and external genitalia at scheduled time-points.

Results

Forty-six boys were recruited, with subgroup sizes FT AGA n=23, FT SGA n=11 and PT n=12. PT boys display a pulsatile pattern of urinary gonadotropins (uGns) with higher levels of uLH and a gradual increase of uTs. Testicular descent started from 29-32 weeks with the peak of uTs. During the first 12-months post-term age (PTA), FT AGA boys displayed a better linear growth (p<0.05). PT showed higher uGns levels until 3-months PTA. PT babies had higher uLH levels than FT AGA, with a peak at 7 and 30 days, during the first 90 days of life (p<0.001) and higher uTs levels. Correlation analysis between penile growth of all neonates and uTs was significant (p=0.04) but not within subgroups.

Conclusion

This study investigated postnatal HPG axis activation in term and PT infants. Minipuberty may involve an early window of opportunity to evaluate the functionality of the HPG axis. Further studies with a long-term follow-up are needed with a special focus on possible consequences of GA and BW.

Laser temperature programmed desorption: A flexible technique to study ion-surface interaction

Understanding the physical-chemical processes ruling the interaction of particles (atoms, molecules, and ions) with surfaces is fundamental in several research fields, such as heterogeneous catalysis, astrochemistry, and nuclear fusion. In particular, the interaction of hydrogen isotopes with plasma facing materials represents a high-priority research task in the fusion community. Such studies are essential to ensure the successful operation of experimental fusion reactors, such as the tokamak ITER. In this work, we present a surface science apparatus developed to study ion-surface interaction in fusion relevant systems. It combines laser-based techniques with contaminant-free ion/molecular beams, mass spectrometry, and surface science tools such as low-energy electron diffraction and Auger electron spectroscopy. It allows to cover a wide range of sample temperatures, from 130 to 2300 K, by changing the heating rate of samples from 0.1 to 135 K/s and maintaining the linearity of the heating ramps, a powerful feature to gain insight on adsorption, absorption, and desorption mechanisms. Experimental calibration and performance are presented in detail. Moreover, to provide a factual overview of the experimental capabilities, we focus on two different applications: the protocol used to clean a W(110) single crystal sample and the development of laser temperature programmed desorption to study helium retention in tungsten.

A high power laser facility to conduct annealing tests at high temperature

The knowledge of material properties and their behavior at high temperatures is of crucial importance in many fields. For instance, annealing phenomena occurring during the thermomechanical processing of materials, such as recrystallization, have long been recognized as being both of scientific interest and technological importance. Different methods are currently used to study annealing phenomena and submit metals to heat loads. In this work, we present the design and the development of a laser-based facility for annealing tests. This experimental setup enables studies at the laboratory scale with great flexibility to submit samples to various spatial and temporal heating profiles. Due to the possibility of having optical access to the sample, laser heating can be combined with several non-contact diagnostics such as infrared imaging to control and analyze the temperature gradients. As a case study, we present a set of experiments performed to study the recrystallization kinetics of tungsten. We demonstrate that samples can be heated linearly with heating rate up to ∼2000 K/s, at temperatures above 2000 K, for seconds or hours, with typical errors in the temperature measurement of around 1% that depend mainly on the determination of sample emissivity. Such studies are of crucial interest in the framework of nuclear fusion since the international thermonuclear experimental reactor nuclear reactor will operate with a full-W divertor.

FSHR polymorphism p.N680S mediates different responses to FSH in vitro

The single nucleotide polymorphism p.N680S of the follicle-stimulating hormone (FSH) receptor (FSHR) is a discrete marker of ovarian response but previous in vitro studies failed to demonstrate differences in the response to FSH between N and S carrier cells. Here we demonstrate that p.N680S mediates different kinetics of the response to FSH in vitro. Intracellular cAMP production is faster in p.N680S N than in S homozygous human granulosa cells (45 versus 90 min to achieve the plateau, respectively; Mann-Whitney's U-test; p < 0.005; n = 4). Reflecting the cAMP kinetics, phospho-ERK1/2 and -CREB activation, AREG and STARD1 gene expressions and progesterone production were qualitatively and quantitatively different in N versus S homozygous cells. Finally, the blockade of ERK pathway by U0126 abolishes the genotype-mediated different effects on gene expression and progesterone production (Mann-Whitney's U-test; p ≥ 0.005; n = 3).

Influence of age and sex on serum concentrations of total dimeric activin A

Several studies have shown that activin A is secreted in substantial amounts into the systemic circulation. The changes that occur during menstrual cycle and pregnancy suggest a correlation with reproductive function. At present, however, no definitive evidence has confirmed this pattern throughout adult life; moreover, neither the origin nor the physiological implications of this circulating growth factor have been clearly defined. The aim of the present study was to evaluate whether circulating concentrations of activin A change in adult men and women according to age and sex, and to examine the possible correlation with serum concentrations of FSH. Total dimeric activin A was measured using a specific two-site enzyme immunoassay in serum specimens collected from a cohort of normal individuals enrolled in an epidemiological survey. A group of men (n = 106) and one of women (n=151) were subdivided into six age groups (20-30, 30-40, 40-50, 50-60, 60-70 and 70-90 years). In a small group of 8 men and 11 women, serum concentrations of activin A were evaluated twice, in specimens collected at an interval of 10 years. Serum FSH concentrations were also measured in all specimens. Serum concentrations of activin A were not significantly different in men and women and showed an age-related progressive increase between 20 and 50 years of age (P<0.01, those aged 40-50 compared with those aged 20-30 years). After the age of 50 years, activin A concentrations remained in the same range of values in women, whereas they increased significantly in men, reaching peak values between 70 and 90 years (P<0.01 compared with the group aged between 20 and 50 years). From the age of 50 years, activin A concentrations were significantly greater in men compared with those in women in the corresponding age groups (P<0.001). Activin A concentrations correlated with age in men, but not in women. No significant correlation between concentrations of activin A and FSH was found in either sex. Activin A concentrations in specimens collected 10 years apart showed an increase in seven of eight men, but not in women. Finally, no significant variations of activin A concentrations were observed when fertile and postmenopausal women were compared. The present data indicate that circulating concentrations of activin A vary according to age; furthermore, men older than 50 years have greater concentrations than women. These changes, which occur irrespectively of FSH concentrations, indicate that circulating activin A is not a hormone of the reproductive axis.

Endogenous dopaminergic activity in Child-Pugh A cirrhosis: potential role in renal sodium handling and in the maintenance of clinical compensation

BACKGROUND

We studied the main determinants of aldosterone secretion in a group of 20 patients with biopsy-proven Child-Pugh A cirrhosis without previous ascites or diuretic consumption.

METHODS

We evaluated the plasma levels of adrenocorticotrophic hormone (ACTH), active renin and aldosterone (both supine at 07.00 h and after 30 min of upright posture),and active renin and aldosterone responses 30 min and 60 min after the administration of metoclopramide, a dopamine DA2 antagonist (10 mg e.v.). Nine normal subjects were also submitted to the metoclopramide stimulation test.

RESULTS

Compared with control subjects, the patients showed significantly greater incremental aldosterone responses both 30 min and 60 min after metoclopramide (+30 min: 157.5+/-73.3 vs. 83.5+/-32.2 pg mL(-1), P< 0003; +60 min: 142.1+/-87.2 vs. 36.8+/-39.0 pg mL(-1), P < 0-001). We found significant positive correlations between amplitude of aldosterone response 30 min after metoclopramide and 24-h urinary fractional excretion of sodium (r=0.61, P < 0.01) and basal morning aldosterone levels (r=0.69, P < 0.001).

CONCLUSIONS

The higher incremental aldosterone responses observed after metoclopramide in cirrhotic patients are expressions of increased dopaminergic activity in these patients compared with control subjects. Moreover, the correlation we found between the degree of dopaminergic activity and 24-h urinary fractional excretion of sodium suggests a role for endogenous dopamine as a relevant mediator of natriuresis in cirrhosis, at least in patients with compensated disease.