Hydrated silicate minerals on Mars observed by the Mars Reconnaissance Orbiter CRISM instrument.

Phyllosilicates, a class of hydrous mineral first definitively identified on Mars by the OMEGA (Observatoire pour la Mineralogie, L'Eau, les Glaces et l'Activitié) instrument, preserve a record of the interaction of water with rocks on Mars. Global mapping showed that phyllosilicates are widespread but are apparently restricted to ancient terrains and a relatively narrow range of mineralogy (Fe/Mg and Al smectite clays). This was interpreted to indicate that phyllosilicate formation occurred during the Noachian (the earliest geological era of Mars), and that the conditions necessary for phyllosilicate formation (moderate to high pH and high water activity) were specific to surface environments during the earliest era of Mars's history. Here we report results from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) of phyllosilicate-rich regions. We expand the diversity of phyllosilicate mineralogy with the identification of kaolinite, chlorite and illite or muscovite, and a new class of hydrated silicate (hydrated silica). We observe diverse Fe/Mg-OH phyllosilicates and find that smectites such as nontronite and saponite are the most common, but chlorites are also present in some locations. Stratigraphic relationships in the Nili Fossae region show olivine-rich materials overlying phyllosilicate-bearing units, indicating the cessation of aqueous alteration before emplacement of the olivine-bearing unit. Hundreds of detections of Fe/Mg phyllosilicate in rims, ejecta and central peaks of craters in the southern highland Noachian cratered terrain indicate excavation of altered crust from depth. We also find phyllosilicate in sedimentary deposits clearly laid by water. These results point to a rich diversity of Noachian environments conducive to habitability.

From Hippocrates to Palmaz-Schatz, the history of carotid surgery.

The extracranial carotid artery is the most common site for peripheral vascular procedures. Although the association of carotid disease and neurologic dysfunction was understood by the ancient Greeks, over 1700 years would pass before the relevant anatomy was described. In the 16th and 17th centuries, attempts at treatment of carotid injury and aneurysm by ligation were met with extremely high rates of stroke and death. It is not until the mid 20th century, with the introduction of carotid angiography and improved vascular surgical techniques, that the era of reconstructive carotid surgery begins. We present a synopsis of the history of carotid surgery from ancient times to present day.

Tension pneumothorax as a complication of video-assisted thorascopic surgery for anterior correction of idiopathic scoliosis in an adolescent female.

STUDY DESIGN: This case report illustrates the occurrence of intraoperative tension pneumothorax, a previously unreported complication occurring during anterior instrumentation for correction of scoliosis by video-assisted surgery. OBJECTIVES: To demonstrate a consequence of overadvancement of a Steinmann pin (guide wire). SUMMARY OF BACKGROUND DATA: Although intraoperative tension pneumothorax is admitted to be a theoretical complication of video-assisted surgery for anterior correction of idiopathic scoliosis, there has yet to be a case reported in the literature. This report presents the first case of this complication. METHODS: A 13-year-old girl who had right thoracic scoliosis with a curve measuring 54 degrees underwent video-assisted surgery discectomy and anterior spinal fusion with instrumentation of T5 through T11. Single-lung ventilation had been achieved with a double-lumen tube and the right lung was deflated. After approximately 4.5 hours of complication-free surgery, intraoperative fluoroscopy showed an approximately 2-cm overadvancement of a guide wire into the opposite hemithorax. Approximately 5 minutes after the overadvancement was corrected, the patient experienced a gradual increase in heart rate and a corresponding gradual decrease in oxygen saturation and both systolic and diastolic blood pressures. Approximately 35 minutes later, it was determined that the patient had sustained a tension pneumothorax of the left hemithorax. RESULTS: The patient underwent urgent partial reinflation of the right lung and a tube thoracostomy of the left thoracic cavity. Vital signs quickly returned to stable levels, and the left lung easily reinflated with the chest tube suction. The patient remained stable after the procedure was resumed (by right lung deflation). The remainder of the surgery and the postoperative course were uneventful. CONCLUSIONS: Although video-assisted surgery continues to gain popularity in the management of spinal deformities, the surgical team must be certain to pay meticulous attention to detail throughout the procedure. The early detection and treatment of complications can be life-preserving.

Results following surgery for recurrent Dupuytren's disease.

This study was designed to assess the subjective and objective results following surgery for recurrent Dupuytren's disease. Nineteen patients (28 fingers) were treated surgically for recurrent contracture and were located for follow-up analysis at a median of 4 years (range, 1-15 years). Seventeen of 28 recurrences involved the small finger and 16 patients had at least one component of Dupuytren's diathesis. For the purpose of analysis the patients were divided into 3 groups: group A (total active range of motion [TAM] < 150 degrees ) consisted of 7 digits treated with limited fasciectomy and interphalangeal arthrodesis, group B (TAM >/= 150 degrees ) consisted of 8 digits treated with dermatofasciectomy and full-thickness skin graft, and group C (TAM >/= 150 degrees ) consisted of 13 digits treated with fasciectomy and local flaps. Total active range of motion reflecting the preoperative, immediately postoperative, and final follow-up values revealed that group C (fasciectomy and local flap) was the only group to maintain a statistically significant TAM improvement from preoperative (205 degrees ) to final follow-up (230 degrees ) analysis. Dermatofasciectomy and full-thickness skin grafting did not prevent recurrent contracture (preoperative TAM = 175 degrees; final follow-up TAM = 150 degrees ). Thirteen patients had abnormal Semmes-Weinstein monofilament testing and 8 had abnormal 2-point discrimination. There were 3 anesthetic digits. Despite these findings, 18 of the 19 patients were unconditionally satisfied with their experience and would undergo the procedure again.

Results from the Mars Global Surveyor Thermal Emission Spectrometer.

The Thermal Emission Spectrometer spectra of low albedo surface materials suggests that a four to one mixture of pyroxene to plagioclase, together with about a 35 percent dust component provides the best fit to the spectrum. Qualitative upper limits can be placed on the concentration of carbonates (<10 percent), olivine (<10 percent), clay minerals (<20 percent), and quartz (<5 percent) in the limited regions observed. Limb observations in the northern hemisphere reveal low-lying dust hazes and detached water-ice clouds at altitudes up to 55 kilometers. At an aerocentric longitude of 224 degrees a major dust storm developed in the Noachis Terra region. The south polar cap retreat was similar to that observed by Viking.

Detection of ozone on Saturn's satellites Rhea and Dione.

The satellites Rhea and Dione orbit within the magnetosphere of Saturn, where they are exposed to particle irradiation from trapped ions. A similar situation applies to the galilean moons Europa, Ganymede and Callisto, which reside within Jupiter's radiation belts. All of these satellites have surfaces rich in water ice. Laboratory studies of the interaction of charged-particle radiation with water ice predicted the tenuous oxygen atmospheres recently found on Europa and Ganymede. However, theoretical investigations did not anticipate the trapping of significantly larger quantities of O2 within the surface ice. The accumulation of detectable abundances of O3, produced by the action of ultraviolet or charged-particle radiation on O2, was also not predicted before being observed on Ganymede. Here we report the identification of O3 in spectra of the saturnian satellites Rhea and Dione. The presence of trapped O3 is thus no longer unique to Ganymede, suggesting that special circumstances may not be required for its production.

Standardizing laparoscopic procedure time and determining the effect of patient age/gender and presence or absence of surgical residents during operation. A prospective multicenter trial.

BACKGROUND: Most of the expense of laparoscopic cholecystectomy (LC) is incurred while the patient is in the operating room (OR). Half of this operating room cost is equipment and the other half is personnel. What is an acceptable LC procedure time and how much variation is there? What are the effects of age, gender, and expertise on the mean LC procedure time? METHODS: A prospective, multicenter gathering of LC procedure times and task component times was performed through the cooperative effort of members of the Society of American Gastrointestinal Endoscopic Surgeons (SAGES) at 11 hospitals. The effect of LC time of age, gender, and surgical resident was recorded. RESULTS: The mean LC time for 359 cases was 73 +/- 28 min. The percent of this LC time for the following component tasks included: to place and remove trocars, 34%; total dissection time, 40%; intraoperative cholangiogram, 15%; and removing the gallbladder, 7%. Age and gender did not change LC time, but the presence of a surgical resident prolonged LC time from 53 to 79 min due to an increase in all LC component task times. CONCLUSIONS: LC time was globally calibrated in 11 North American hospitals and was found to be affected by expertise but not by gender or age. The mean and standard deviation of LC time can be used for purposes of self-assessing quality performance.

Management and long-term follow-up of patients with positive cholangiograms during laparoscopic cholecystectomy.

BACKGROUND: With a goal of minimal invasion during laparoscopic cholecystectomy, the surgeon confronts a judgement decision if the intraoperative cholangiography (IOC) is positive for common bile duct (CBD) stones. The options are postoperative endoscopic retrograde cholangiopancreatography (ERCP) with endoscopic papillotomy (EP), transcystic laparoscopic techniques (LAP), open CBD exploration, or clinical observation. PATIENTS AND METHODS: To gather this information, we reviewed the clinical course and IOC of 55 patients with positive IOC during laparoscopic cholecystectomy. Long-term follow-up (1.8 years) was obtained in 50 patients. RESULTS: After review, 48 patients were felt to have CBD stones, and a LAP without choledochoscopy was the initial management in 32 (67%) patients. The remaining patients underwent EP (n = 10), CBD exploration (n = 1), or observation (n = 5). By discharge, 19 (59%) of the 32 LAP patients were successful and had avoided EP while the success rate at follow-up was 48% (14/29). There were no complications after LAP, but we observed a 9.5% (2/21) post-EP pancreatitis rate that required readmission. The success rate for CBD stone clearance with LAP was associated with single stones (87%) and surgeon experience (100% in the last year). The average hospital stay was 1.7 days for LAP and 3.3 days for EP. CONCLUSIONS: LAP is safe and eliminates the need for EP in the majority of cases. Although EP is more often successful, it results in a longer hospital stay with an increased risk of complication. We recommend LAP as the initial procedure of choice for a positive IOC.

Ices on the surface of triton.

The near-infrared spectrum of Triton reveals ices of nitrogen, methane, carbon monoxide, and carbon dioxide, of which nitrogen is the dominant component. Carbon dioxide ice may be spatially segregated from the other more volatile ices, covering about 10 percent of Triton's surface. The absence of ices of other hydrocarbons and nitriles challenges existing models of methane and nitrogen photochemistry on Triton.

Surface ices and the atmospheric composition of pluto.

Observations of the 1.4- to 2.4-micrometer spectrum of Pluto reveal absorptions of carbon monoxide and nitrogen ices and confirm the presence of solid methane. Frozen nitrogen is more abundant than the other two ices by a factor of about 50; gaseous nitrogen must therefore be the major atmospheric constituent. The absence of carbon dioxide absorptions is one of several differences between the spectra of Pluto and Triton in this region. Both worlds carry information about the composition of the solar nebula and the processes by which icy planetesimals formed.

Derivation of midinfrared (5-25 micrometers) optical constants of some silicates and palagonite.

The midinfrared 2000-400 cm-1 (5-25 micrometers) optical constants (real (n) and imaginary (k) indices of refraction) are presented for: (1) pyrophyllite; (2) kaolinite; (3) serpentine; (4) montmorillonite; (5) saponite; (6) palagonite; and (7) orthopyroxene. Comparison of the values derived here with those previously presented for serpentine, montmorillonite, and palagonite is generally quite good and discrepancies between values are probably due to either chemical differences between the actual samples or different techniques used to derive the values. For montmorillonite, saponite, and palagonite we were able to derive optical constants in the region of the H2O-bending fundamental near 6 micrometers. We find that if a pellet of pure material can be produced with a mirror-like surface then the optical constants of clays and other noncohesive materials can be readily derived.

Benzo(a)pyrene 7,8-dihydrodiol-9,10-oxide modification of DNA: relation to chromatin structure and reconstitution.

Purified duck reticulocyte DNA was incubated in vitro with a 7,8-dihydrodiol-9,10-oxide derivative of benzo(a)pyrene (BPDE). The carcinogen-modified DNA was somewhat more susceptible to partial digestion by the single strand specific endonuclease S1 than unmodified DNA, suggesting slight denaturation of the helix at sites of modification. Chromatin was reconstituted in vitro utilizing this carcinogen-modified DNA and unmodified-chromatin associated proteins. This reconstituted chromatin showed the same kinetics and extent of digestion by Staphylococcal nuclease, and similar nucleosome profiles on sucrose density gradient centrifugation, as those obtained with native chromatin or chromatin reconstituted with unmodified DNA. Moreover, polyacrylamide gel electrophoresis of DNA fragments obtained from nuclease digests gel electrophoresis of DNA fragments obtained from nuclease digests of the reconstituted chromatins suggested that the chromatin containing carcinogen-modified DNA had the same subnucleosome structure as that reconstituted with unmodified DNA. In a separate set of studies intact duck reticulocyte chromatin was reacted directly with BPDE. Nuclease digestion studies indicated that 65% of the carcinogen was bound to the 'open' regions of chromatin, and 35% to 'closed' regions. These results indicate that although convalent binding of a benzo(a)pyrene (BP) derivative to DNA produces local distortions in conformation of the helix, this modification does not appear to interfere with the ability of the DNA to associate with histones to form nucleosome structures. In addition, although DNA in the open regions of chromatin is more susceptible to reaction with the BP derivative, there is appreciable reaction with the DNA associated with histones.