Radiation-induced alteration of apatite on the surface of Mars: first in situ observations with SuperCam Raman onboard Perseverance.

Planetary exploration relies considerably on mineral characterization to advance our understanding of the solar system, the planets and their evolution. Thus, we must understand past and present processes that can alter materials exposed on the surface, affecting space mission data. Here, we analyze the first dataset monitoring the evolution of a known mineral target in situ on the Martian surface, brought there as a SuperCam calibration target onboard the Perseverance rover. We used Raman spectroscopy to monitor the crystalline state of a synthetic apatite sample over the first 950 Martian days (sols) of the Mars2020 mission. We note significant variations in the Raman spectra acquired on this target, specifically a decrease in the relative contribution of the Raman signal to the total signal. These observations are consistent with the results of a UV-irradiation test performed in the laboratory under conditions mimicking ambient Martian conditions. We conclude that the observed evolution reflects an alteration of the material, specifically the creation of electronic defects, due to its exposure to the Martian environment and, in particular, UV irradiation. This ongoing process of alteration of the Martian surface needs to be taken into account for mineralogical space mission data analysis.

Reasons for failure of total temporomandibular joint replacement: a systematic review and meta-analysis.

The aim of this study was to evaluate the revision rate after total alloplastic temporomandibular joint replacement (TMJR) and determine whether there is a higher risk of revision surgery with stock or custom-fitted prostheses (the two most current TMJR prosthesis types). A systematic review was performed, with a search of PubMed, Google Scholar, and the Cochrane Library in November 2020. Overall, 27 articles were included in this study, describing Biomet and TMJ Concepts prostheses and including postoperative data on complications requiring a return to the operating room. A total of 2247 prostheses were analysed: 1350 stock Biomet prostheses and 897 custom-fitted TMJ Concepts and custom-fitted Biomet prostheses. The global revision rate was 1.19 per 100 prosthesis-years. The most common reason for revision was heterotopic bone formation. Stock prostheses appeared to have a lower risk of revision compared to custom prostheses: rate ratio 0.52 (95% confidence interval 0.33-0.81, P-value 0.003). Regarding causes of revision, the only significant difference between the types of devices was a higher rate of heterotopic bone formation for custom-made prostheses (P = 0.001). The results of this study revealed a low revision rate post TMJR revision, with stock devices even less prone to such risk. Nevertheless, these results can be explained by the fact that custom-made prostheses are more likely to be used for cases in which the anatomy is significantly abnormal or there is a history of multiple joint surgeries, which carry a greater risk of complications and heterotopic bone formation.

Association of surgical excision and brachytherapy for the management of keloids.

Many techniques have been described to prevent the appearance and relapse of keloids but most of them have an efficacy lower than 50%. Our objective is to describe our standardized management of keloids by associated surgery and brachytherapy. Surgery-brachytherapy is usually given only when less invasive treatments failed. Both a surgeon and a radiotherapist are involved. Forty-eight hours of hospitalization in a surgery unit are required. The extra-lesional excision is performed and a brachytherapy sheath is placed in the dermis plane. An iridium source with an initial activity of 300 GBq is used to deliver high dose rate brachytherapy. The brachytherapy sessions are held in a lead-shielded room in a radiotherapy unit: the first session at 6 h after surgical excision, while the second and third on the following day. The total dose administered is 18 Gy. A surgical workup is scheduled at 10 days. The patient is followed-up closely by the radiotherapist for an 18-month period. The recurrence rate after 2 years is 8 to 12%. The main complaints are dyschromia, telangiectasia and skin atrophy.

Impact of a rehabilitation program on muscular strength and endurance in peripheral arterial occlusive disease patients.

UNLABELLED: Rehabilitation care and physical exercise are known to constitute an effective treatment for chronic peripheral arterial occlusive disease (PAOD) at the intermittent claudication (IC) stage. Improvements in functional capacities and quality of life have been reported in the literature. We decided to assess the effects of hospital-based exercise training on muscle strength and endurance for the ankle plantar and dorsal flexors in this pathology. PATIENTS AND METHODS: This prospective study included 31 subjects with chronic peripheral arterial occlusive disease (PAOD) and IC who followed a 4-week rehabilitation program featuring walking sessions, selective muscle strengthening, general physical exercise and therapeutic patient education. An isokinetic assessment of ankle plantar and dorsal flexors strength was conducted on the first and last days of the program. We also studied the concentric contractions at the angular velocity of 30°/s and 120°/s for muscle strength and at 180°/s for muscle fatigue. We also measured the walking distance for each patient. RESULTS: Walking distance improved by 246%. At baseline, the isokinetic assessment revealed severe muscle weakness (mainly of the plantar flexors). The only isokinetic parameter that improved during the rehabilitation program was the peak torque for plantar flexors at 120°/s. CONCLUSION: All patients presented with severe weakness and fatigability of the ankle plantar and dorsal flexors. Our program dramatically improved walking distance but not muscle strength and endurance.

Mutations within the MGC4607 gene cause cerebral cavernous malformations.

Cerebral cavernous malformations (CCM) are hamartomatous vascular malformations characterized by abnormally enlarged capillary cavities without intervening brain parenchyma. They cause seizures and focal neurological deficits due to cerebral hemorrhages. CCM loci have already been assigned to chromosomes 7q (CCM1), 7p (CCM2), and 3q (CCM3) and have been identified in 40%, 20%, and 40%, respectively, of families with CCM. Loss-of-function mutations have been identified in CCM1/KRIT1, the sole CCM gene identified to date. We report here the identification of MGC4607 as the CCM2 gene. We first reduced the size of the CCM2 interval from 22 cM to 7.5 cM by genetic linkage analysis. We then hypothesized that large deletions might be involved in the disorder, as already reported in other hamartomatous conditions, such as tuberous sclerosis or neurofibromatosis. We performed a high-density microsatellite genotyping of this 7.5-cM interval to search for putative null alleles in 30 unrelated families, and we identified, in 2 unrelated families, null alleles that were the result of deletions within a 350-kb interval flanked by markers D7S478 and D7S621. Additional microsatellite and single-nucleotide polymorphism genotyping showed that these two distinct deletions overlapped and that both of the two deleted the first exon of MGC4607, a known gene of unknown function. In both families, one of the two MGC4607 transcripts was not detected. We then identified eight additional point mutations within MGC4607 in eight of the remaining families. One of them led to the alteration of the initiation codon and five of them to a premature termination codon, including one nonsense, one frameshift, and three splice-site mutations. All these mutations cosegregated with the disease in the families and were not observed in 192 control chromosomes. MGC4607 is so far unrelated to any known gene family. Its implication in CCMs strongly suggests that it is a new player in vascular morphogenesis.

Compressive thoracic spondylodiscitis associated with a pleural abscess: Surgical treatment through an enlarged posterior approach.

The authors report a case of a patient with paraparesis secondary to T5-T6 spondylodiscitis accompanied by a closely lying, well-formed pleural abscess. This rare association has previously been reported only twice in the literature. The technical difficulty of surgery for both the abscess and the compressive spondylodiscitis was resolved by the use of an enlarged posterior approach. This approach enabled evacuation of the pleural lesion, curettage of the disc space, interbody grafting, and spinal osteosynthesis in one stage.

The case for radioprotective eyewear/facewear. Practical implications and suggestions.

Numerous eyeglass lens materials have been recommended for protection of radiologists' eyes from the cataractogenic effect of radiation during fluoroscopic procedures. For the most part, these lenses coincidentally attenuate x-ray beams because they contain elements of high atomic number that are added to increase refractive index. With a bean hardened to simulate scatter, direct transmission ratios were measured for 32 commercially available lens materials. Scatter to the eye, both through and around the glass lenses and secondary scatter to the eye from the radiologist's head, was determined with lenses mounted on a head phantom and a 1-cm3 ion chamber in the position of the eye. Transmission ratios for the various lenses ranged from 3% to 98% for an 80 kVp x-ray beam (HVL = 4.5 mm Al). Measurements with the head phantom in place show that secondarily scattered radiation from the fluoroscopist's head contributes significantly to ocular exposure. Optimal radiation protection of the eyes during fluoroscopy depends not only on eyeglasses with leaded glass, but also on shielding of sufficient size and shape to reduce exposure to the surrounding head.