Mesenteric and retroperitoneal cysts are rare intra-abdominal tumors. Ten new patients are presented as well as 152 other cases reported in the English literature. These 162 cases were then analyzed for significant trends. Patients under 10 years of age were significantly different from the older group with respect to a shorter duration of symptoms, a higher number of patients requiring an emergency operation, a lower number of recurrences and the location of the cyst. Patients with retroperitoneal cysts were more likely to have incomplete excision of the cyst and therefore had a higher incidence of recurrence. They also required marsupialization more often. Retroperitoneal cysts should be considered a different entity from mesenteric cysts even though they present clinically in a similar fashion. The outcome of surgical treatment is less satisfactory in patients with retroperitoneal cysts.

Microgravity and hypoactivity are associated with skeletal muscle deconditioning. The decrease of muscle mass follows an exponential decay, with major changes in the first days. The purpose of the study was to dissect out the effects of a short-term 3-day dry immersion (DI) on human quadriceps muscle function and structure. The DI model, by suppressing all support zones, accurately reproduces the effects of microgravity. Twelve healthy volunteers (32 ± 5 years) completed 3 days of DI. Muscle function was investigated through maximal voluntary contraction (MVC) tests and muscle viscoelasticity. Structural experiments were performed using MRI analysis and invasive experiments on muscle fibres. Our results indicated a significant 9.1% decrease of the normalized MVC constant (P = 0.048). Contraction and relaxation modelization kinetics reported modifications related to torque generation (k = -29%; P = 0.014) and to the relaxation phase (k = +34%; P = 0.040) after 3 days of DI. Muscle viscoelasticity was also altered. From day one, rectus femoris stiffness and tone decreased by, respectively, 7.3% (P = 0.002) and 10.2% (P = 0.002), and rectus femoris elasticity decreased by 31.5% (P = 0.004) after 3 days of DI. At the cellular level, 3 days of DI translated into a significant atrophy of type I muscle fibres (-10.6 ± 12.1%, P = 0.027) and an increased proportion of hybrid, type I/IIX fibre co-expression. Finally, we report an increase (6-fold; P = 0.002) in NCAM+ muscle fibres, showing an early denervation process. This study is the first to report experiments performed in Europe investigating human short-term DI-induced muscle adaptations, and contributes to deciphering the early changes and biomarkers of skeletal muscle deconditioning.

BackgroundDry immersion (DI), a ground-based model of microgravity previously used in Russia, has been recently implemented in France. The aim of this study was to analyze early events in a short-term DI model in which all conditions are met to investigate who is first challenged from osteo- or adipo-kines and to what extent they are associated to insulin-regulating hormones.MethodsTwelve healthy men were submitted to a 3-day DI. Fasting blood was collected during pre-immersion phase for the determination of the baseline data collection (BDC), daily during DI (DI24h, DI48H and DI72h), then after recovery (R+3h and R+24h). Markers of bone turnover, phosphocalcic metabolism, adipokines and associated factors were measured.ResultsBone resorption as assessed by tartrate-resistant acid phosphatase isoform 5b and N-terminal crosslinked telopeptide of type I collagen levels increased as early as DI24h. At the same time, total procollagen type I N- and C-terminal propeptides and osteoprotegerin, representing bone formation markers, decreased. Total osteocalcin [OC] was unaffected, but its undercarboxylated form [Glu-OC] increased from DI24h to R+3h. The early and progressive increase in bone alkaline phosphatase activities suggested an increased mineralization. Dickkopf-1 and sclerostin, as negative regulators of the Wnt-β catenin pathway, were unaltered. No change was observed either in phosphocalcic homeostasis (calcium and phosphate serum levels, 25-hydroxyvitamin D, fibroblast growth factor 23 [FGF23]) or in inflammatory response. Adiponectemia was unchanged, whereas circulating leptin concentrations increased. Neutrophil gelatinase-associated lipocalin [lipocalin-2], a potential regulator of bone homeostasis, was found elevated by 16% at R+3h compared to DI24h. The secretory form of nicotinamide phosphoribosyl-transferase [visfatin] concentrations almost doubled after one day of DI and remained elevated. Serum insulin-like growth factor 1 levels progressively increased. Fasting insulin concentrations increased during the entire DI, whereas fasting glucose levels tended to be higher only at DI24h and then returned to BDC values. Changes in bone resorption parameters negatively correlated with changes in bone formation parameters. Percent changes of ultra-sensitive C-reactive protein positively correlated with changes in osteopontin, lipocalin-2 and fasting glucose. Furthermore, a positive correlation was found between changes in FGF23 and Glu-OC, the two main osteoblast-/osteocyte-derived hormones.ConclusionOur results demonstrated that DI induced an unbalanced remodeling activity and the onset of insulin resistance. This metabolic adaptation was concomitant with higher levels of Glu-OC. This finding confirms the role of bone as an endocrine organ in humans. Furthermore, visfatin for which a great responsiveness was observed could represent an early and sensitive marker of unloading in humans.

Venoconstrictive thigh cuffs are used by cosmonauts to ameliorate symptoms associated with cephalad fluid shift. A ground simulation of microgravity, using the dry immersion (DI) model, was performed to assess the effects of thigh cuffs on body fluid changes and dynamics, as well as on cardiovascular deconditioning. Eighteen healthy men (25-43 years), randomly divided into two groups, (1) control group or (2) group with thigh cuffs worn 10 h/day, underwent 5-day DI. Cardiovascular responses to orthostatic challenge were evaluated using the lower body negative pressure (LBNP) test; body fluid changes were assessed by bio-impedance and hormonal assay; plasma volume evolution was estimated using hemoglobin-hematocrit; subjective tolerance was assessed by questionnaires. DI induced a decrease in plasma volume of 15-20%. Reduction in total body water of 3-6% stabilized toward the third day of DI. This reduction was derived mostly from the extracellular compartment. During the acute phase of DI, thigh cuffs limited the decrease in renin and the increase in N-terminal prohormone of brain natriuretic peptide (NT-proBNP), the loss in total body water, and tended to limit the loss in calf volume, extracellular volume and plasma volume. At the later stable phase of DI, a moderate protective effect of thigh cuffs remained evident on the body fluids. Orthostatic tolerance time dropped after DI without significant difference between groups. Thigh cuff countermeasure slowed down and limited the loss of body water and tended to limit plasma loss induced by DI. These observed physiological responses persisted during periods when thigh cuffs were removed. However, thigh cuffs did not counteract decreased tolerance to orthostatic challenge.