Increase in 6-hydroxymelatonin excretion in humans during ascent to high altitudes

Melatonin (MLT), the pineal gland hormone involved in the regulation of circadian rhythms, shows characteristic diurnal variation. Its physiological role in humans is not clear. Exposure to high altitudes may disrupt the circadian rhythm and lead to various endocrine changes. MLT in humans has not been studied under these conditions. Urinary 6-hydroxy-MLT sulfate (aMT6s) excretion was analyzed during the day (0700-2200 h) and night (2200-0700 h) phases. A cohort of 33 healthy volunteers, aged 19-65 yr, was studied during an ascent to a high altitude in the Himalayas on three occasions (at a lower altitude, at 3400 m, and after reaching maximal altitudes of 5600-6100 m). aMT6s excretion during the daytime remained unchanged during exposure to high altitudes. As expected, nocturnal values were higher than diurnal values at each point in time. However, there was a significant increase in nocturnal MLT excretion after the ascent to high altitudes. Ascent to high altitudes is associated with increased nocturnal excretion of aMT6s. The mechanism and physiological significance of this MLT increase are unclear.     

Preclinical In Vitro Assessment of Submicron-Scale Laser Surface Texturing on Ti6Al4V

Loosening of orthodontic and orthopedic implants is a critical and common clinical problem. To minimize the numbers of revision surgeries due to peri-implant inflammation or insufficient osseointegration, developments of new implant manufacturing strategies are indicated. Ultrafast laser surface texturing is a promising contact-free technology to modify the physicochemical properties of surfaces toward an anti-infectious functionalization. This work aims to texture Ti6Al4V surfaces with ultraviolet (UV) and green (GR) radiation for the manufacturing of laser-induced periodic surface structures (LIPSS). The assessment of these surface modifications addresses key aspects of topography, morphology and chemical composition. Human primary mesenchymal stromal cells (hMSCs) were cultured on laser-textured and polished Ti6Al4V to characterize the surfaces in terms of their in vitro biocompatibility, cytotoxicity, and metal release. The outcomes of the in vitro experiment show the successful culture of hMSCs on textured Ti6Al4V surfaces developed within this work. Cells cultured on LIPSS surfaces were not compromised in terms of their viability if compared to polished surfaces. Yet, the hMSC culture on UV-LIPSS show significantly lower lactate dehydrogenase and titanium release into the supernatant compared to polished. Thus, the presented surface modification can be a promising approach for future applications in orthodontics and orthopedics.     

Three-Dimensional CT Volumetry Predicts Outcome of Laparoscopic Splenectomy for Splenomegaly: Retrospective Clinical Study

Background

The aim of this study was to determine the predictive value of the preoperative three-dimensional reconstructed volume (3D volumetry) for outcomes of laparoscopic splenectomy. The impact of splenomegaly on the feasibility of laparoscopic splenectomy is still debated. We hypothesized that splenic volumetry may accurately estimate splenic volume preoperatively and be used by surgeons to select patients for laparoscopic splenectomy.

Methods

We performed a retrospective review of 88 patients seen at a tertiary referral center undergoing laparoscopic or open splenectomy between 2001 and 2010. Patients included in the study underwent elective splenectomy without associated procedures and had preoperative imaging available at our institution. We evaluated clinical, demographic characteristics and perioperative imaging as predictors of outcome. Study endpoints included conversion to open splenectomy, operating time, estimated blood loss (EBL), length of stay (LOS), postoperative complications, and mortality.

Results

In all, 53 procedures were started laparoscopically. Among them, 7 (13.2 %) were converted to open splenectomy and 7 (13.2 %) to hand-assisted laparoscopic splenectomy. The conversion group was matched with 35 patients who underwent open splenectomy to determine differences in outcomes between these groups. There were no conversions in spleens measuring <1100 cc, whereas spleens of 1100 to 2700 cc had a conversion rate of 41 %. Spleen volume >2700 cc was associated with an 87.5 % conversion rate. Spleen 3D volumetry >2700 cc was the only independent predictor of surgical conversion on multivariate analysis (odds ratio 38.0, confidence interval 4.02–358.75, p = 0.001). Patients who underwent open splenectomy had shorter operating times (160.3 vs. 253.0 min, p = 0.001) than those converted from laparoscopic to open splenectomy.

Conclusions

A 3D reconstructed splenic volume of >2700 cc is a predictor of conversion from laparoscopic to open splenectomy. For spleens measuring <2700 cc, laparoscopic splenectomy may be performed by experienced surgeons with low to moderate rates of conversion. For spleens with a 3D reconstructed volume >2700 cc, laparoscopic splenectomy is associated with high rates of conversion to open surgery.