The Atacama Rover Astrobiology Drilling Studies (ARADS) Project

With advances in commercial space launch capabilities and reduced costs to orbit, humans may arrive on Mars within a decade. Both to preserve any signs of past (and extant) martian life and to protect the health of human crews (and Earth's biosphere), it will be necessary to assess the risk of cross-contamination on the surface, in blown dust, and into the near-subsurface (where exploration and resource-harvesting can be reasonably anticipated). Thus, evaluating for the presence of life and biosignatures may become a critical-path Mars exploration precursor in the not-so-far future, circa 2030. This Special Collection of papers from the Atacama Rover Astrobiology Drilling Studies (ARADS) project describes many of the scientific, technological, and operational issues associated with searching for and identifying biosignatures in an extreme hyperarid region in Chile's Atacama Desert, a well-studied terrestrial Mars analog environment. This paper provides an overview of the ARADS project and discusses in context the five other papers in the ARADS Special Collection, as well as prior ARADS project results.

Kappa: Preliminary Results on a Novel Technique for Pelvic Fixation in Adult Spinal Deformity Correction

Study Design

Retrospective cohort study.

Objectives

Pelvic fixation in degenerative spinal deformation is as crucial as demanding. Several pelvic anchoring technics have been described, but loosening rates remain high for most solutions. Here is described the "Kappa" technic, combining ilio-sacral screws to S2A1 screws at 2 years of follow-up.

Methods

Thirteen patients that underwent a spinal deformity correction with "Kappa" fixation to the pelvis and with more than 2 years of follow-up were prospectively included in this study. The surgical technic is described, and clinical and radiographic data have been collected for all patients.

Results

The population exhibited an important pre-operative sagittal imbalance (mean SVA of 104,4 mm, mean PI-LL mismatch of 22,8°) that had improved significatively after surgery (mean SVA of 75,5 mm and mean PI-LL mismatch of 4,9°). No loosening of pull-out of the implants was to deplore at 2 years of follow-up.

Conclusions

The association of ilio-sacral screw, resistant to pull-out because of the traction axis perpendicular to the construct, to S2A1 screws, known to be effective in sagittal balance restoration seems to be an effective and safe option to pelvic fixation for adult spinal deformity correction.

Level of Evidence

IV.

Functional results and patient satisfaction after long fusion for spinal deformity in Parkinson's disease

BACKGROUND

Patients with Parkinson's disease often present abnormal posture or severe sagittal malalignment, causing significant disability. Surgical fusion is these cases shows high rates of complications, but may nevertheless provide functional benefit; however, this remains to be assessed.

HYPOTHESIS

Long fusion for patients with Parkinson's disease and postural disorder could alleviate disability despite the high risk of complications.

METHODS

We retrospectively reviewed 18 Parkinson patients treated by long fusion for spinal deformity. Functional results on the Oswestry Disability Index (ODI) and patient satisfaction were assessed at a minimum 2 years' follow-up. Predictive factors for good outcome were analyzed.

RESULTS

Median follow-up was 44.4 months (IQR, 36-62.4 months). ODI showed significant improvement, from 64 (IQR, 59-77) preoperatively to 49 (IQR, 40-57) at last follow-up (p=0.0014). Fifteen patients (83%) were very satisfied (n=5) or satisfied (n=10) with the procedure. On multivariate analysis, only age was significantly associated with improvement in ODI at last follow-up (estimate: -9.8; p=0.5).

DISCUSSION

Although long spinal fusion involves a high risk of complications in Parkinson's patients, the improvement in autonomy and patient satisfaction should be borne in mind before rejecting surgery, especially with motivated patients.

LEVEL OF EVIDENCE

IV.

Osteosynthesis in sacral fracture and lumbosacral dislocation

Sacral fracture and lumbosacral hinge trauma are rare but serious lesions. Neurologic disorder is frequently associated, and nerve release may be required, with reduction and stabilization of the fracture. Management requires knowing the fracture lines and reduction maneuvers and the fixation techniques that may need to be associated. Three classifications allow these fractures to be well understood: the Roy-Camille classification identifies high transverse fractures and their displacement; the Denis classification identifies vertical fracture line location within the sacrum, which correlates with neurologic risk; and the Tile classification analyzes pelvic ring trauma when associated with the sacral fracture. Treatment, when surgical, requires careful patient positioning, sometimes on an orthopedic table. Reduction maneuvers are founded on the fracture classification. Isolated U-shaped fracture of the sacrum is to be distinguished from sacral fracture associated with pelvic ring lesion. Osteosynthesis may be lumbopelvic or restricted to the pelvic ring (sacroiliac or iliosacral). Open osteosynthesis allows reduction to be finalized by intraoperative maneuvers on the implant, while closed osteosynthesis requires perfect preoperative reduction. Complications are frequent and neurologic recovery is uncertain. Fatigue and osteoporotic fractures show little displacement and are good indications for cementoplasty, either isolated or associated to iliosacral screwing. In lumbosacral hinge trauma, and dislocation in particular, reduction surgery with fixation (usually 360°) is indicated. The present study details the analysis and classification of these fractures, the technical pitfalls of reduction and fixation, and treatment indications.

[Mesoglycan in acute and chronic venous insufficiency of the legs]

Fifty-eight patients with acute and chronic pathology of the lower limbs were treated with daily oral doses of 96 mg of mesoglycan, a drug having antithrombotic and fibrinolytic properties. After a 3-months trial both clinical picture and instrumental parameters were found to be improved.

Isocitrate lyase from Pinus pinea. Characterization of its true substrate and the action of magnesium ions

We found that the Mg-isocitrate complex is the true substrate for pine isocitrate lyase and that magnesium acts as a non-essential activator. Both the non-activated and the activated enzyme forms are catalytically active. Our model is consistent with the presence of two Mg-binding sites with different affinities: an activator site with high affinity in addition to the catalytic site with lower affinity. This may result in a complex, fine regulation of isocitrate lyase activity by magnesium. The affinity of the free enzyme for isocitrate is very low. Moreover, free isocitrate does not bind to the activated enzyme, nor it can yield a catalytically active form by binding to an enzyme species whose catalytic site has already been bound by magnesium.