HELQ deficiency impairs the induction of primordial germ cell-like cells.

Helicase POLQ-like (HELQ) is a DNA helicase essential for the maintenance of genome stability. A recent study identified two HELQ missense mutations in some cases of infertile men. However, the functions of HELQ in the process of germline specification are not well known and whether its function is conserved between mouse and human remains unclear. Here, we revealed that Helq knockout (Helq-/-) could significantly reduce the efficiency of mouse primordial germ cell-like cell (PGCLC) induction. In addition, Helq-/- embryonic bodies exhibited a severe apoptotic phenotype on day 6 of mouse PGCLC induction. p53 inhibitor treatment could partially rescue the generation of mouse PGCLCs from Helq mutant mouse embryonic stem cells. Finally, the genetic ablation of HELQ could also significantly impede the induction of human PGCLCs. Collectively, our study sheds light on the involvement of HELQ in the induction of both mouse and human PGCLCs, providing new insights into the mechanisms underlying germline differentiation and the genetic studies of human fertility.

[Effects of 7 d head-down bed rest on human vectorcardiogram (VCG)].

OBJECTIVE: To study the effects of short-term simulated weightlessness on human vectorcardiogram (VCG). METHOD: Seven d -6 degrees head-down bed rest (HDBR) was used to simulate weightlessness. Eight healthy males, aged 19-21, served as the subjects. VCG was recorded before and on day 1, 3, 7 of HDBR. RESULT: QRS loop in the horizontal plane rotated counterclockwise, while QRS loop in the right sagittal plane rotated clockwise during HDBR (P<0.05 or P<0.01). QRS-T angle in the horizontal and right sagittal plane increased significantly during HDBR. CONCLUSION: Seven d HDBR leads to changes of VCG parameters, which were all in normal ranges and in accordance with the volume changes of atrium and ventricle, but obviously different from those resulted from pathological ventricular thickening and myocardial ischemia.

[Effects of body position changes on frequency domain correlative cardiogram in pilots].

OBJECTIVE: To study the effects of the body position changes on FCG in pilots so as to explore the possibility of using FCG as an indicator of medical monitoring and medical support. METHOD: 65 pilots were examined in 4 different body positions, i.e. supine position, head-down position, standing position and sitting position. Twelve channel routine electrocardiogram was recorded synchronously, and their complaints were also recorded. RESULT: The grade distribution and abnormal cases of the FCG varied with the body positions. The orders of changing magnitude were: the standing position, the head-down position, the sitting position and the supine position. The changes accorded with that of 12 channels routine ECG synchronously recorded and complaints of the subjects. CONCLUSION: The FCG was an objective index representing the cardiac functional status.

Impact of 60 days of 6° head down bed rest on cardiopulmonary function, and the effects of Taikong Yangxin Prescription as a countermeasure.

OBJECTIVE: To study the changes in cardiopulmonary function induced by mid/long-term simulated microgravity with 6° head down bed rest (HDBR), and the effects of Taikong Yangxin Prescription (, TYP) as a countermeasure. METHODS: Fourteen healthy male volunteers were randomly divided into a control group and a Chinese medicine (CM) group (7 in each group) by a random digital table based on their body weight. Both groups underwent 6° HDBR for 60 days. Subjects in the CM group received daily TYP pills and subjects in the control group received daily placebo pills. Cardiac systolic and pumping functions were measured by echocardiography before HDBR; on days 20, 42, and 57 of HDBR; and on day 3 of recovery after HDBR (R+3). Cardiopulmonary functional reserve and exercise capacity were evaluated before HDBR, on day 29, and on day R+3 by exercise testing. RESULTS: The heart rate (HR) increased gradually during HDBR. The HR was significantly higher on day 57 than before HDBR in the control group (P<0.05), but did not increase significantly in the CM group. The stroke volume/stroke volume index, ejection fraction, and left ventricular fractional shortening tended to decrease over time in the control group, but not in the CM group. These parameters were significantly higher in the CM group than in the control group on day 42 (P<0.05 or <0.01). Exercise testing showed that maximum O2 consumption (VO2max), metabolic equivalents, relative O2 consumption (VO2), O2 pulse, and exercise duration were significantly lower on day 29 than before HDBR in the control group, but not in the CM group. CONCLUSIONS: Sixty days of 6° HDBR induced a reduction in cardiac systolic and pumping functions, and reduced cardiopulmonary functional reserve and exercise capacity. Administration of TYP significantly improved cardiac systolic and pumping functions, and maintained cardiopulmonary functional reserve and exercise capacity.