RESUMEN
Prematurity has been linked to lower muscular fitness and increased morbidity across the human lifespan. Hand grip strength is widely used as a measure of muscle strength. Previous studies have shown inconsistent results regarding the role of vitamin D in hand grip strength. Here, we investigated hand grip strength and the effects of a yearlong vitamin D supplementation in healthy preterm-born young adults. We recruited 38 young adults born preterm at either ≤32 weeks' gestation or <34 weeks' gestation and weighing <1500 g, as well as 39 gender- and age-matched controls, for this study. Anthropometric measurements, hand grip strengths, and vitamin D concentrations were recorded. These investigations were repeated after a yearlong vitamin D supplementation intervention. There was a significant difference in the age- and gender-specific hand grip strength ranks between the preterm- and full-term-born young adults: 57.9% and 30.7%, respectively, were below average (p = 0.009). In the preterm-born group, the females had significantly lower hand grip strengths compared to their full-term-born peers, with a mean difference of -3.46 kg (95% CI: -6.68 to -0.247; p = 0.035). In a linear regression analysis, the preterm-born female adult height was negatively associated with hand grip strength (R2 = 0.24, F (1.43) = 13.61, p < 0.001). The vitamin D concentrations were increased after the supplementation period, with no association with hand grip strength. According to our results, preterm-born young females are at risk for lower muscle strength, independent of their current vitamin D status.
RESUMEN
Prematurity has been associated with impaired parasympathetic cardiac regulation later in life. Changes in heart rate (HR) and heart rate variability (HRV) may indicate a risk for future cardiac dysfunction. The putative role of Vitamin D on cardiac autonomic function in individuals born preterm (PT) remains unknown. This study involves monitoring autonomic cardiac regulation and Vitamin D concentrations in 30 PT and 16 full-term (FT) young adults in a free-living context. The PT subjects were born between 1994 and 1997 at Oulu University Hospital. The inclusion criteria were (1) being born ≤ 32 gestation weeks or (2) being born < 34 gestation weeks with a birth weight under 1500 g. Participants wore an Oura ring sleep tracer, a smart ring device, for 2 weeks to monitor cardiac autonomic function. Parameters related to autonomic cardiac regulation, lowest nighttime resting HR, and the root mean square of successive differences (RMSSD) to describe HRV were collected. PT males exhibited a tendency toward lower RMSSD (71.8 ± 22.6) compared to FT males (95.63 ± 29.0; p = 0.10). Female participants had a similar mean RMSSD in the FT and PT groups at 72.04 ± 33.2 and 74.0 ± 35.0, respectively. Serum 25-hydroxyvitamin D concentration did not correlate with cardiac autonomic function parameters. When assessing the lowest resting nighttime HRs and HRVs in a long-term, real-world context, healthy female PT young adults performed similarly to their FT peers. In contrast, the present study's results suggest that male PT young adults exhibit impaired autonomic cardiac function, potentially putting them at risk for cardiovascular disease later in adulthood.
RESUMEN
OBJECTIVE: In a sheep model we tested the hypothesis that the fetal left ventricle is less tolerant to worsening acidemia than the right ventricle. STUDY DESIGN: At 106-124/145 days of gestation, 12 fetuses were instrumented. After a 4-day recovery, placental vascular resistance was increased by fetal angiotensin (AT) II infusion. After a 2h ATII infusion, to further deteriorate fetal oxygenation, maternal hypoxemia was induced. Fetal cardiac function and hemodynamics were assessed by tissue Doppler imaging (TDI) and pulsed Doppler imaging. Ultrasonography was performed at baseline, at 1 and 2h after the beginning of ATII infusion and during the ATII+hypoxemia phase. RESULTS: Fetal pH and pO2 decreased significantly and progressively during the experiment. Left ventricular TDI-derived isovolumic relaxation velocity (IVRV) was lower during ATII 2h and ATII+hypoxemia phases than at baseline. The IVRV deceleration was significantly less during the ATII+hypoxemia phase than at baseline. Right ventricular IVRV was significantly lower during the ATII+hypoxemia phase than at baseline. IVRV deceleration did not change. Only left ventricular IVRV deceleration correlated with fetal pO2 (R=0.36, p<0.05). Fetal right and left ventricular cardiac outputs, as well as umbilical artery, aortic isthmus and ductus venosus pulsatility indices remained unchanged during the experiment. CONCLUSION: Our results show that signs of cardiac dysfunction develop earlier in the left ventricle than in the right ventricle. The fetal left ventricle seems to be more sensitive to progressively worsening hypoxemia and acidemia than the right ventricle.
