Minerals in the gut: scoping a Cambrian digestive system.

The Sirius Passet Lagerstätte of North Greenland contains the first exceptionally preserved mat-ground community of the Cambrian, dominated, in terms of abundance, by trilobites but particularly characterized by iconic arthropods and lobopods, some also occurring in the Burgess shale. High-resolution photography, scanning electron imaging and elemental mapping have been carried out on a variety of specimens of the non-mineralized arthropod Campanamuta mantonae (Budd 2011 J. Syst. Palaeontol.9, 217-260 (doi:10.1080/14772019.2010.492644)) which has three-dimensional gut and muscle preservation. Results show that the guts contain a high concentration of calcium phosphate (approximating to the mineral francolite), whereas the adjacent muscles are silicified. This indicates a unique, tissue-specific taphonomy for this Cambrian taxon. We hypothesize that the precipitation of calcium phosphate in the guts occurs rapidly after death by 'crystal seed' processes in suboxic, slightly acidic conditions; critically, the gut wall remained intact during precipitation. We postulate that the calcium phosphate was derived from ingested cellular material. Silicification of the muscles followed as the localized water chemistry became saturated in silica, high in Fe2+, and low in oxygen and sulfate. We document here the unique occurrence of two distinct but mechanistically similar taphonomic pathways within a diverse suite of possibilities in an Early Cambrian Lagerstätte.

Development and validation of the Curtin Back Screening Questionnaire (CBSQ): a discriminative disability measure.

Disability accompanying occupational low back pain (LBP) can include a wide range of incapacitating symptoms which, for the practitioner, can be time-consuming and difficult to identify systematically. A questionnaire designed for case-finding and assessment could assist in both the early recognition of disability and in planning management. A suitable questionnaire for clinical use could not be found in the literature. The Curtin Back Screening Questionnaire (CBSQ) was developed, therefore, as a discriminative screening instrument to serve this purpose. The methods and results of the development and validation of the CBSQ are presented herein. Development of the questionnaire followed the principles of Kirschner and Guyatt (1985) employing data from 74 subjects with at least moderately severe work-related LBP. The research design for the validation was multiple-group repeated-measures with a study population of 150 subjects. The screening function of the questionnaire was developed through selecting 8 questions from the whole questionnaire using regression analysis. The questionnaire includes 79 items based on the subjects' perceived health status. The response structure of the CBSQ has been adapted from that of the General Health Questionnaire (GHQ) and some items in the CBSQ have been developed from items in the Sickness Impact Profile (SIP) and GHQ. The questionnaire discriminates effectively between subjects with different degrees of disability, it correlates quite well with the SIP, test-retest reliability for the whole questionnaire is 0.98, the receiver-operating characteristics are more favourable than those for the SIP, and the CBSQ screening score provides an index of severity which correlates with work incapacity.(ABSTRACT TRUNCATED AT 250 WORDS)

Evolution of a neonatal gentamicin dosing protocol in a small community hospital.

The effects of conventional dosage of gentamicin of 2.5 mg/kg given every 12 hours was retrospectively investigated in a small community hospital. Consistent with previous results in large hospitals, the conventional dosage of gentamicin commonly resulted in serum concentrations associated with toxicosis. Results were compared with those obtained prospectively according to a gentamicin dosing protocol that used a formula based on gestational age. The gestational age regimen provided similar peak and significantly lower trough serum concentrations; statistical analysis indicated no demographic differences in the compared groups. Very few neonates who received gentamicin according the gestational age formula were exposed to gentamicin serum concentrations associated with an increased risk of toxicosis. An absence of any significant differences in mean peak and trough serum concentrations in subgroups of neonates treated according to the gestational age formula suggested that use of the gentamicin dosing protocol was appropriate for all neonates. The dose of 3.5 mg/kg used in the gestational age formula was predicted to have resulted in initial gentamicin peak serum concentrations > 5 micrograms/ml in nearly 90% of neonates. The experience obtained with the gestational age formula allowed revision of the gentamicin dosing protocol to provide for more cost-responsible serum concentration monitoring.

Quantitation of 5-(hydroxymethyl)uracil in DNA by gas chromatography with mass spectral detection.

5-(Hydroxymethyl)uracil is a product of oxidative DNA damage. This hydroxylated base was quantified in DNA by GC-MS using either acid or enzymatic hydrolysis of the DNA and isotopically labeled internal standards. Both 5-(hydroxymethyl)uracil and thymine were quantified in each DNA sample and the results expressed as a ratio. This procedure controlled for possible errors in the quantitation of DNA prior to hydrolysis and derivatization. In addition, quantitation of thymine was important due to possible variations in DNA hydrolysis efficiency for each sample. The isotopically labeled internal standards controlled for compound instability through the procedure and for variations in derivatization efficiency. The conditions used for acid hydrolysis of the DNA resulted in considerable degradation of 5-(hydroxymethyl)uracil; however, since isotopically labeled 5-(hydroxymethyl)uracil was added prior to acid treatment, 5-(hydroxymethyl)uracil still could be quantified. The degradation of 5-(hydroxymethyl)uracil was avoided using enzymatic hydrolysis of the DNA. In DNA that had been treated with hydrogen peroxide and iron in the presence of EDTA, the observed level of 5-(hydroxymethyl)uracil using enzymatic hydrolysis was 1.6-fold higher than when using acid hydrolysis of the DNA. With analysis of 2 micrograms of DNA, the detection limit for 5-(hydroxymethyl)uracil was 3/10(5) thymines.

Comprehensive quality assessment approach for flow cytometric immunophenotyping of human lymphocytes.

Flow cytometric immunophenotypic (IPT) evaluation has become an important adjunct to clinical patient management and epidemiological studies. This has precipitated a need for stringent quality assessment (QA) procedures to ascertain data integrity. We evaluated a QA approach to monitor all elements of the immunophenotyping process, inclusive of blood collection and processing procedures as well as of staining reagent and instrument performance. Central to our approach was preparation each day, in parallel with clinical analytes, of lymphocytes from healthy donors, selected from a 15 donor panel. IPT parameters evaluated over a 19 month period included frequencies of CD3+, CD4+, CD8+, and CD20+ lymphocytes and the ratio of CD4+ to CD8+ lymphocytes. The sensitivity for analytical error detection was reflected by median coefficients of variation of these parameters within individual panel donors, which were 4.1%, 4.5%, 3.9%, 8.2%, and 10.1%, respectively. IPT parameter values were determined each day for two of the panel donors, then averaged and standardized to obtain a quality or Q variate, which was the basis of QA. Error detection sensitivity decreased 0.6-1.7% and the number of false rejections increased 1.2-3.3% when one panel donor rather than two was used daily for QA. This study also illuminated important aspects of what constitutes the norm for longitudinal IPT parameter variation in healthy individuals including: 1) a generally low degree of temporal parameter variation within individual donors, but 2) significant differences between donors with respect to variance estimates for CD3+ and CD8+ lymphocyte frequencies and CD4+/CD8+ lymphocyte ratios, and 3) an apparent seasonal pattern of variation in CD4+ T-cell frequencies.

An epidemiological description of physical, social and psychological problems in multiple sclerosis.

Chronic disorders such as multiple sclerosis have important behavioural consequences on the lives of patients. The purpose of this study was to describe the frequency distribution of psychosocial disability among a referral clinic population of multiple sclerosis patients and to identify associated factors. A cross-sectional survey was conducted of 301 patients using four health indexes to assess quality of life. An 82% response rate was obtained. In the results are presented the frequencies of behavioural problems compared with the general population and a family practice group. While physical function was found to be closely associated with disease severity, psychosocial disability bore little relationship to the underlying disease or to sociodemographic variables including social class. Eighty percent of psychosocial disability remained unexplained. The physical aspects of multiple sclerosis were not predictive of emotional or social morbidity. The major implication of these findings is that the impact of disease on patients, as distinct from the disease itself, should be dealt with as health problems in their own right.

Heat trap: an optimized far infrared field optics system.

An ir field optics system has been designed that achieves the maximum flux concentration allowed by the Abbe sine inequality and provides efficient coupling to bolometer-type detectors.