Evidence that chronic hypoxia causes reversible impairment on male fertility

Aim: To evaluate the effect of chronic hypoxia on human spermatogenic parameters and their recovery time. Methods: Seminological parameters of six male healthy mountain trekkers were evaluated in normoxia at sea level. After 26 days exposure to altitude (ranging from 2 000 m to 5 600 m, Karakorum Expedition) the same parameters were again evaluated after returning to sea level. These parameters were once again evaluated after 1 month and then again after 6 months. Results: Sperm count was found to be lower immediately after returning to sea level (P = 0.0004) and again after a month (P = 0.0008). Normal levels were reached after 6 months. Spermatic motility (%) shows no reduction immediately after returning to sea level (P = 0.0583), whereas after 1 month this reduction was significant (P = 0.0066). After 6 months there was a recovery to pre-hypoxic exposure values. Abnormal or immature spermatozoa (%) increased immediately after returning to sea level (P = 0.0067) and then again after 1 month (P = 0.0004). After 6 months there was a complete recovery to initial values. The total number of motile sperm in the ejaculate was found to be lower immediately after returning to sea level (P = 0.0024) and then again after 1 month (P = 0.0021). After 6 months there was a recovery to pre-hypoxic exposure values. Conclusion: Chronic hypoxia induces a state of oligospermia and the normalization of such seminological parameters at the restoration of previous normoxic conditions after 6 months indicate the influence of oxygen supply in physiological mechanisms of spermatogenesis and male fertility. (Asian J Androl 2008 Jul; 10: 602–606

The critical view of safety during laparoscopic cholecystectomy: Strasberg Yes or No? An Italian Multicentre study

Background: Laparoscopic cholecystectomy is considered the gold standard for the treatment of gallbladder lithiasis; nevertheless, the incidence of bile duct injuries (BDI) is still high (0.3–0.8%) compared to open cholecystectomy (0.2%). In 1995, Strasberg introduced the "Critical View of Safety" (CVS) to reduce the risk of BDI. Despite its widespread use, the scientific evidence supporting this technique to prevent BDI is controversial. Methods: Between March 2017 and March 2019, the data of patients submitted to laparoscopic cholecystectomy in 30 Italian surgical departments were collected on a national database. A survey was submitted to all members of Italian Digestive Pathology Society to obtain data on the preoperative workup, the surgical and postoperative management of patients and to judge, at the end of the procedure, if the isolation of the elements was performed according to the CVS. In the case of a declared critical view, iconographic documentation was obtained, finally reviewed by an external auditor. Results: Data from 604 patients were analysed. The study population was divided into two groups according to the evidence (Group A; n = 11) or absence (Group B; N = 593) of BDI and perioperative bleeding. The non-use of CVS was found in 54.6% of procedures in the Group A, and 25.8% in the Group B, and evaluating the operator-related variables the execution of CVS was associated with a significantly lower incidence of BDI and intraoperative bleeding. Conclusions: The CVS confirmed to be the safest technique to recognize the elements of the Calot triangle and, if correctly performed, it significantly impacted on preventing intraoperative complications. Additional educational programs on the correct application of CVS in clinical practice would be desirable to avoid extreme conditions that may require additional procedures

Gene clusters reflecting macrodomain structure respond to nucleoid perturbations

Focusing on the DNA-bridging nucleoid proteins Fis and H-NS, and integrating several independent experimental and bioinformatic data sources, we investigate the links between chromosomal spatial organization and global transcriptional regulation. By means of a novel multi-scale spatial aggregation analysis, we uncover the existence of contiguous clusters of nucleoid-perturbation sensitive genes along the genome, whose expression is affected by a combination of topological DNA state and nucleoid-shaping protein occupancy. The clusters correlate well with the macrodomain structure of the genome. The most significant of them lay symmetrically at the edges of the ter macrodomain and involve all of the flagellar and chemotaxis machinery, in addition to key regulators of biofilm formation, suggesting that the regulation of the physical state of the chromosome by the nucleoid proteins plays an important role in coordinating the transcriptional response leading to the switch between a motile and a biofilm lifestyle.Comment: Article: first 24 pages, 3 figures Supplementary methods: 1 page, 1 figure Supplementary results: 14 pages, 11 figure

How a Rear Steering System May Improve Motorcycle Dynamics, 328 Int. J. Vehicle Design,

This research investigates how motorcycle dynamics may be improved by applying a steering system on the rear wheel. The study is carried out using a widely validated multi-body model of motorcycle and rider. Two types of rear steering systems are compared: a self-steering wheel coupled with a spring-damper assembly and a controlled steering wheel, whose steering angle is governed accordingly to a first-order relationship between front and rear steering angle. In general, any rear steering system transfers energy from weave mode to wobble mode. Thus, both solutions stabilise high-speed weave, but increase instability when braking. The passive system shows unexpected reactions when accelerating in cornering condition, whereas the active system is almost neutral

The Modal Analysis of a Motorcycle in Straight Running and on a Curve

The vibrational modes (generalized) of a two-wheel vehicle are studied in several trim configurations. The modal analysis is carried out on a 3D non-linear mathematical model, developed using the natural coordinates approach. A special procedure for evaluating the steady state solutions in straight running and on a curve is proposed. The paper presents detailed results of the modal analysis for a production sports motorcycle. Furthermore, the influence of speed and lateral (centripetal) acceleration on stability, shape and modal interactions (coupling) is highlighted. Finally, consistency between the first experimental tests and simulation results is shown