Organic molecules in the Sheepbed Mudstone, Gale Crater, Mars

The Sample Analysis at Mars (SAM) instrument on board the Mars Science Laboratory Curiosity rover is designed to conduct inorganic and organic chemical analyses of the atmosphere and the surface regolith and rocks to help evaluate the past and present habitability potential of Mars at Gale Crater. Central to this task is the development of an inventory of any organic molecules present to elucidate processes associated with their origin, diagenesis, concentration, and long-term preservation. This will guide the future search for biosignatures. Here we report the definitive identification of chlorobenzene (150-300 parts per billion by weight (ppbw)) and C₂ to C₄ dichloroalkanes (up to 70 ppbw) with the SAM gas chromatograph mass spectrometer (GCMS) and detection of chlorobenzene in the direct evolved gas analysis (EGA) mode, in multiple portions of the fines from the Cumberland drill hole in the Sheepbed mudstone at Yellowknife Bay. When combined with GCMS and EGA data from multiple scooped and drilled samples, blank runs, and supporting laboratory analog studies, the elevated levels of chlorobenzene and the dichloroalkanes cannot be solely explained by instrument background sources known to be present in SAM. We conclude that these chlorinated hydrocarbons are the reaction products of Martian chlorine and organic carbon derived from Martian sources (e.g., igneous, hydrothermal, atmospheric, or biological) or exogenous sources such as meteorites, comets, or interplanetary dust particles.

KEY POINTS

First in situ evidence of nonterrestrial organics in Martian surface sediments Chlorinated hydrocarbons identified in the Sheepbed mudstone by SAM Organics preserved in sample exposed to ionizing radiation and oxidative condition.

The effect of total hip and hip resurfacing arthroplasty on vertical ground reaction force and impulse symmetry during a sit-to-stand task

BACKGROUND

The aim of this study was to determine the influence of total hip arthroplasty and hip resurfacing arthroplasty on limb loading symmetry before, and after, hip reconstruction surgery during a sit-to-stand task.

METHODS

Fourteen patients were recruited that were about to receive either a total hip prosthesis (n=7) or a hip resurfacing prosthesis (n=7), as well as matched controls. Patients performed a sit-to-stand movement before, 3 months after, and 12 months after surgery. Peak vertical ground reaction force and impulse were measured for each leg, from which ground reaction force and impulse symmetry ratios were calculated.

FINDINGS

Before surgery, hip resurfacing patients showed a small asymmetry which was not different to normal for ground reaction force (0.88(0.28) vs. 1.00(0.11); p=0.311) or impulse (0.87(0.29) vs. 0.99(0.09); p=0.324) symmetry ratios. Total hip patients offloaded their affected hip by 30% in terms of impulse symmetry ratio (0.71(0.36) vs. 0.99(0.23); p=0.018). At 3 months following surgery asymmetries were seen that were different to normal in both hip resurfacing patients for ground reaction force (0.77(0.16); p=0.007), and total hip patients for ground reaction force (0.70(0.15); p=0.018) and impulse (0.72(0.16); p=0.011) symmetry ratios. By 12 months after surgery total hip patients regained a symmetrical loading pattern for both ground reaction force (0.95(0.06); p=0.676) and impulse (1.00(0.06); p=0.702) symmetry ratios. Hip resurfacing patients, however, performed the task by overloading their operated hip, with impulse symmetry ratio being larger than normal (1.16(0.16); p=0.035).

INTERPRETATION

Physiotherapists should appreciate the need for early recovery of limb loading symmetry as well as subsequent differences in the responses observed with different prostheses.

Phenotypic evaluation of severely damaged ocular surface after reconstruction by cultured limbal epithelial cell transplantation

OBJECTIVE

To report the clinical outcome of autologous cultured limbal epithelial cell transplantation (CLECT) followed by deep anterior lamellar keratoplasty (DALK) in paediatric eyes and to correlate the clinical outcome with the phenotype of rejuvenated corneal epithelium.

METHODS

Four patients with total limbal stem cell deficiency (LSCD) underwent autologous CLECT. Cultivated cell sheets were transplanted onto the damaged ocular surface followed by DALK surgery. Excised corneal buttons were subjected to histopathological analysis. Data recorded included age, sex, laterality, nature of injury, follow-up period, severity of stem cell deficiency, visual acuity, Schirmer's test and impression cytology.

RESULTS

At a mean follow-up period of 19.5 ± 7.4 (range 9-26) months after CLECT, all 4 eyes showed epithelialized and clinically stabilized ocular surface. Manual DALK was performed in all 4 eyes, with a mean follow-up of 9.75 ± 4.5 (range 5-15) months. All eyes exhibited smooth and clear corneal epithelium with improved visual acuity. Excised corneal buttons demonstrated organized corneal epithelial morphology and showed expression of cornea-specific CK3/12 marker.

CONCLUSION

Restoration of severely damaged ocular surface following chemical injury by using 2-stage meticulous approaches offers a new modality for the treatment of severe LSCD. Transplantation of cultivated autologous limbal epithelial cell sheet followed by DALK surgery can efficiently restore the corneal phenotype with improved vision.

Computational Modeling Deduced Three Dimensional Structure of Cry1Ab16 Toxin from Bacillus thuringiensis AC11

The first theoretical structural model of newly reported Cry1Ab16 δ-endotoxin produced by Bacillus thuringiensis AC11 was predicted using homology modeling technique. Cry1Ab16 resembles the Cry1Aa protein structure by sharing a common three domains structure responsible in pore forming and specificity determination along with few structural deviations. The main differences between the two is in the length of loops, absence of α7b, α9a, α10b, α11a and presence of additional β12b, α13 components while α10a is spatially located at downstream position in Cry1Ab16. A better understanding of the 3D structure shall be helpful in the design of domain swapping and mutagenesis experiments aimed at improving toxicity.

Tuberculous lymphadenopathy: a multicentre operational study of 6-month thrice weekly directly observed treatment

SETTING

Eight operational locations for the Revised National Tuberculosis Control Programme in six Indian states.

OBJECTIVE

To assess the 6-month efficacy of an intermittent thrice-weekly directly observed treatment (DOT) regimen for tuberculous peripheral adenopathy and the need for prolongation of treatment to 9 months for non-resolution of lymphadenopathy.

DESIGN

Patients aged >5 years with tuberculous lymphadenopathy were included in the study. Patients were evaluated for resolution at repeat visits following treatment. Those with poor resolution at 6 months were randomised to extended treatment up to 9 months or observation without additional treatment.

RESULTS

Resolution of lymphadenopathy was observed at the end of 6 months in 517/551 (93.8%) patients. There was a significant difference in response among patients with and those without the presence of systemic symptoms. There was no association between treatment response and number, size, site, consistency and matting of lymphadenopathy. No differences in response were seen in the remaining 34 patients with or without extended treatment.

CONCLUSION

The operational efficacy of 6-month thrice-weekly DOT for peripheral tubercular lymphadenopathy was satisfactory. There was no evidence of additional benefits of prolonging treatment to 9 months.

Peculiar reduction of graphene oxide into graphene after diffusion in exponentially growing polyelectrolyte multilayers

In the present work, in situ reduction of graphene oxide (GO) into graphene was preformed, after diffusion in exponentially growing polyelectrolyte multilayers, using sodium citrate as the reducing agent. First, the graphene oxide was obtained by treating a commercial grade of Expanded Graphite (EG). Based on XRD and Raman spectroscopy results, a complete exfoliation of graphene nanopellets down to one layer was achieved during the oxidation process. Secondly, the diffusion of GO was carried out in an exponentially growing polyelectrolyte multilayer film made from poly(diallyldimethylammonium chloride) as the polycation and from poly(acrylic acid) as the polyanion. Electrical conductivity of the GO based films was measured during the reduction process as a function of time. The conductivity reached values of the order of 10(-4) S cm(-1), whereas the pristine polyelectrolyte multilayer was highly insulating (∼10(-8) S cm(-1)). The conductivity also reached a maximal value after about 24 h of reduction and decreased for longer reduction duration. Some tentative explanations for this peculiar finding will be given.

Retinoblastoma

Retinoblastoma is the most common intraocular malignancy in children and one of the very few life-threatening ophthalmic conditions. Genetically, the disease may be heritable or non-heritable. It can have unilateral or bilateral involvement and can present either sporadically or with a positive family history. Leukocoria and strabismus are the most common presentations. Diagnosis is made by indirect ophthalmoscopy aided by imaging techniques. Multidisciplinary management is aimed at saving lives, salvaging the globe and maintaining good vision. The use of neoadjuvant chemotherapy and focal treatments, such as cryotherapy, laser photocoagulation, transpupillary thermotherapy, brachytherapy and periocular chemotherapy, form the mainstay of globe preserving treatment in retinoblastoma. In developing countries, retinoblastoma is unfortunately accompanied by a high mortality rate due to delayed diagnosis made at advanced stages of the disease. Early diagnosis and timely management are vital for a good prognosis.

Evaluating most probable number method to count and isolate viable methylotrophs

Nine different receptacles were tested with the MPN method to determine which receptacle was most reliable and economical for MPN counts. Results showed that 96 well PCR plate were the best vessels for this type of analysis and facilitated the isolation of viable Methylotrophs.

Prevalence of bronchial asthma in school children of 6-13 years of age in Shimla city

BACKGROUND

Asthma is a major public health problem worldwide. However, there is limited data on asthma prevalence among school children in Shimla. The present study was undertaken to determine the prevalence of asthma in Shimla city and also to examine the different factors influencing its occurrence.

METHODS

This was a questionnaire-based study (International Study of Asthma and Allergies in Childhood [ISAAC] protocol) carried out in four randomly selected schools in the city of Shimla. The questionnaire was pre-tested in 50 school children. The age group included in the study was 6-13 years. The questionnaire was distributed to all the children (n = 1136). A response rate of 89.5% was achieved. The socio-economic status was determined on the basis of monthly income (cumulative square root value method). The ISAAC questionnaire was given standard scores. Various factors influencing the prevalence of asthma, such as socio-economic status, history of asthma and other allergic disorders in the family, type of cooking fuel used, history of active and passive smoking were elucidated from the history.

RESULTS

Overall prevalence of asthma in our study was found to be 2.3 percent. Boys had a higher prevalence (3.1%) than girls (1.4%). We found a significant association between asthma prevalence and family history of asthma and other atopic manifestations. There was no significant association of socio-economic factors and exposure to smoking with prevalence of asthma.

CONCLUSION

In the present study, the prevalence of bronchial asthma in school children in the age group of 6-13 years is 2.3 percent.

Interactions among peripheral perfusion, cardiac activity, oxygen saturation, thermal profile and body position in growing low birth weight infants

AIMS

To investigate the correlation between the 'perfusion index' (PI) and other commonly used estimates of cutaneous blood flow [heart rate (HR), surface temperatures (ST) and central-to-peripheral thermal gradients (C-P grad)] and to use this new non-invasive tool to compare differences between prone and supine sleep position in low birth weight (LBW) infants.

METHODS

Six-hour continuous recordings of pulse oximetry, cardiac activity and absolute ST from three sites (flank, forearm and leg), along with minute-to-minute assessment of behavioural states were performed in 31 LBW infants. Infants were randomly assigned to the prone or supine position for the first 3 h and then reversed for the second 3 h. PI data were correlated with HR and C-P grad, and compared across sleep positions during quiet sleep (QS) and active sleep (AS).

RESULTS

Perfusion index correlated significantly with HR (r(2) = 0.40) and flank-to-forearm thermal gradient (r(2) = 0.28). In the prone position during QS, infants exhibited higher PI (3.7 +/- 0.9 vs. 3.1 +/- 0.7), HR (158.4 +/- 8.9 vs. 154.1 +/- 8.8 bpm), SpO(2) (95.8 +/- 2.6 vs. 95.2 +/- 2.6%), flank (36.7 +/- 0.4 vs. 36.5 +/- 0.4 degrees C), forearm (36.1 +/- 0.6 vs. 35.5 +/- 0.4 degrees C) and leg (35.4 +/- 0.7 vs. 34.7 +/- 0.7 degrees C) temperatures and narrower flank-to-forearm (0.6 +/- 0.4 vs. 0.9 +/- 0.3 degrees C) and flank-to-leg (1.3 +/- 0.6 vs. 1.8 +/- 0.7 degrees C) gradients, compared to those of the supine position. Similar differences were observed during AS.

CONCLUSION

Perfusion index is a good non-invasive estimate of tissue perfusion. Prone sleeping position is associated with a higher PI, possibly reflecting thermoregulatory adjustments in cardiovascular control. The effects of these position-related changes may have important implications for the increased risk for sudden infant death syndrome in prone position.