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PubMed1990

Intake of essential and toxic trace elements in a random sample of Danish men as determined by the duplicate portion sampling technique.

Average daily intakes of essential and toxic trace elements from self-selected diets consumed by 100 men, selected as a random sample among the population of 30-34 year-old men in one urban and two rural areas of Denmark, were determined by the analysis of 48 h duplicate food portions. Median daily dietary intakes were 11.3 mg for zinc, 1.1 mg for copper, 11.3 mg for iron, 51 micrograms for selenium, 3.9 mg for manganese, 99 micrograms for molybdenum, 7 micrograms for lead and 11 micrograms for cadmium. Median dietary intake of mercury was below the detection limit. The observed nitrogen, sodium and potassium intakes were about 25% lower than the average total daily excretion of these constituents. It is therefore assumed that dietary intakes of nutrients during the duplicate portion sampling period were reduced by about 25% and that the observed intakes of trace elements can be regarded as minimum estimates of habitual intake. Taking this into consideration, it is concluded that the content of essential trace elements in Danish diets seems to be adequate and the amounts of the elements lead, mercury and cadmium are of little concern as regards health aspects.

Adult↗
PubMed1995

[A study of rCBF measurement with autoradiography (ARG) method using N-isopropyl-p-[123I]iodoamphetamine (IMP) and SPECT--comparison of rCBF values between look-up table (TLU) and ARG methods, and evaluation of venous blood samplings as a substitute for arterial blood sampling].

Regional cerebral blood flow (rCBF) values obtained by the TLU method with two 123I-IMP SPECT scans and one point arterial blood sampling and rCBF obtained by the ARG method with one 123I-IMP SPECT scan and fixed distribution volume (Vd) values were compared in 17 cases. A case with post ischemic hyperperfusion or luxury perfusion was not observed in our cases. The correlation coefficients between rCBF values and Vd values obtained by the TLU method were 0.49 (p < 0.001) in 184 ROI without hypoactive areas on the early image, and 0.61 (p < 0.001) in 207 ROI with hypoactive areas, respectively. A high rCBF value with a low Vd value was not observed in any region. Mean Vd value was 44.0 +/- 7.0 (mean +/- SD) in all regions. The correlation coefficients between rCBF values using the TLU method and those using the ARG method with Vd fixed at 44 and 50 were also 0.98. Error of the rCBF value was larger in the region of high rCBF, however, noticeable error of the rCBF value was not observed in the ARG method. The ARG method is more convenient for quantifying rCBF. Venous blood radioactivity at 10 min after 123I-IMP infusion was smaller than arterial blood radioactivity, and the blood activity in the distal vein was larger than that in the proximal vein. The ratio of venous blood activity to arterial blood activity was 0.92 +/- 0.04 (mean +/- SD) at the back of the hand, however, the ratio was a variant in each case. Arterial sampling was thought to be a reliable method to obtain more stable and precise rCBF.

Aged↗
PubMed1994

Sample preparation technique for iodine determination in urine and water samples.

A simple method for iodine determination in urine and water samples is presented. After digestion of the sample with chromic acid, the iodate produced was converted to iodide by the addition of a strong solution of sodium sulphite. The iodide was then precipitated as palladium iodide using a solution of palladium chloride. The precipitate was filtered through membrane filter paper, air-dried and analyzed using the Energy Dispersive X-Ray Fluorescence (EDXRF) method.

Humans↗
PubMed1993

Fetal tissue sampling--indications, techniques, complications, and experience with sampling of fetal skin, liver, and muscle.

Invasive prenatal testing has become an important way to evaluate fetuses at increased risk for hereditary disorders. In utero sampling of fetal skin, liver, and muscle may be required to diagnose before-birth disorders that cannot be diagnosed by analysis using chorionic villi or amniotic fluid. In the next few years, many of these conditions will be detected by DNA analysis, and the need for these procedures may decrease dramatically. First performed by fetoscopy, fetal tissue sampling is now most frequently done by inserting a biopsy needle under continuous ultrasonographic guidance. We describe the indications, techniques, complications, and experience with obtaining fetal skin, liver, and muscle biopsy specimens.

Biopsy, Needle↗
PubMed1999

Aalen's linear model for sampled risk set data: a large sample study.

Borgan and Langholz (1997) describe a method for estimating the parameter functions in Aalen's linear hazard regression model from sampled risk set data. Using a counting process formulation and the martingale central limit theorem, we provide a study of the asymptotic distributional properties of the estimator. The results are applied to study the efficiencies of the nested case-control and counter-matched designs relative to a full cohort analysis.

Case-Control Studies↗
PubMed2006

Analysis of sample set enrichment scores: assaying the enrichment of sets of genes for individual samples in genome-wide expression profiles.

MOTIVATION: Gene expression profiling experiments in cell lines and animal models characterized by specific genetic or molecular perturbations have yielded sets of genes annotated by the perturbation. These gene sets can serve as a reference base for interrogating other expression datasets. For example, a new dataset in which a specific pathway gene set appears to be enriched, in terms of multiple genes in that set evidencing expression changes, can then be annotated by that reference pathway. We introduce in this paper a formal statistical method to measure the enrichment of each sample in an expression dataset. This allows us to assay the natural variation of pathway activity in observed gene expression data sets from clinical cancer and other studies. RESULTS: Validation of the method and illustrations of biological insights gleaned are demonstrated on cell line data, mouse models, and cancer-related datasets. Using oncogenic pathway signatures, we show that gene sets built from a model system are indeed enriched in the model system. We employ ASSESS for the use of molecular classification by pathways. This provides an accurate classifier that can be interpreted at the level of pathways instead of individual genes. Finally, ASSESS can be used for cross-platform expression models where data on the same type of cancer are integrated over different platforms into a space of enrichment scores. AVAILABILITY: Versions are available in Octave and Java (with a graphical user interface). Software can be downloaded at http://people.genome.duke.edu/assess.

Algorithms↗
PubMed1988

Detection of linkage between a quantitative trait and a marker locus by the lod score method: sample size and sampling considerations.

A simulation study is here conducted to measure the power of the lod score method to detect linkage between a quantitative trait and a marker locus in various situations. The number of families necessary to detect such linkage with 80% power is assessed for different sets of parameters at the trait locus and different values of the recombination fraction. The effects of varying the mode of sampling families and the sibship size are also evaluated.

Computer Simulation↗
PubMed2006

A multivariate two-sample mean test for small sample size and missing data.

We develop a new statistic for testing the equality of two multivariate mean vectors. A scaled chi-squared distribution is proposed as an approximating null distribution. Because the test statistic is based on componentwise statistics, it has the advantage over Hotelling's T2 test of being applicable to the case where the dimension of an observation exceeds the number of observations. An appealing feature of the new test is its ability to handle missing data by relying on only componentwise sample moments. Monte Carlo studies indicate good power compared to Hotelling's T2 and a recently proposed test by Srivastava (2004, Technical Report, University of Toronto). The test is applied to drug discovery data.

Algorithms↗
PubMed1993

Simultaneous and bilateral inferior petrosal sinus sampling for the diagnosis of Cushing's syndrome: comparison of multihormonal assay, baseline multiple sampling and ACTH-releasing hormone test.

In 29 consecutive patients with adrenocorticotropin (ACTH)-dependent Cushing's syndrome, we compared the usefulness of multiple baseline ACTH evaluations (10/29), multiple hormone evaluation (29/29) and ACTH-releasing hormone (CRH) stimulation (21/29) during simultaneous and bilateral inferior petrosal sinus sampling. The basal inferior petrosal sinus/periphery ratio for ACTH concentrations was greater than 2 in 18 of the 29 patients and CRH challenge caused the appearance of an inferior petrosal sinus/periphery ratio greater than 3 in 6 other patients. The presence of an ACTH-secreting adenoma was surgically proven in all the 24 patients who had an ACTH inferior petrosal sinus/periphery ratio greater than 2 basally or greater than 3 after the CRH test but also in 1 patient who had an inferior petrosal sinus/periphery ratio lower than 2 basally or 3 after the CRH test. In 4 patients, both the very high peripheral ACTH levels, the inferior petrosal sinus/periphery ratio and the complete lack of ACTH increase after CRH indicated the presence of an ectopic ACTH syndrome: a bronchial carcinoid was found in 2 patients, whereas the site of the tumor is still unknown in the remaining 2. An ACTH intersinus gradient greater than 1.4 was found in 23 patients. Among these 23 patients, the side of the adenoma was correctly predicted in 19 patients and wrongly in 4.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Decreasing risk of pregnancy loss following chorionic villus sampling. Elimination of transabdominal chorionic villus sampling during the ninth week of pregnancy.

Chorionic villus sampling (CVS) is a method of obtaining fetal cells in the first trimester of pregnancy for genetic analysis. The transcervical (TC) approach was the first technique to be widely used. In the National Institute of Child Health and Human Development collaborative study the absolute loss rate following CVS (the total number of spontaneous abortions and neonatal deaths following CVS) was 4%. More recently the transabdominal (TA) approach has been introduced. This study compares the loss rates for the two approaches at various gestational ages for three 6-month periods following the addition of the TA approach with each other and with the loss rates prior to the introduction of TA CVS. We found that the percentage of pregnancy losses following TA CVS during the ninth week of gestation (63-69 days) was consistently higher than for TC CVS performed at the same gestational age. The loss rate for TC CVS has steadily decreased since the introduction of TA CVS after remaining the same for the two years prior to the introduction of the TA approach. After minimizing the number of TA CVS performed during the ninth week of gestation, the overall loss rate during the most recent 6-month period has been reduced to 0.94%. We conclude that the lowest loss rate following CVS can be obtained if both the TA and TC methods are available, and that the number of TA procedures performed during the ninth week of gestation is minimized.

Abortion, Spontaneous↗
PubMed1990

[Chorionic villi sampling: experience of the initial 500 samples].

We report our experience in first trimester antenatal diagnosis since 1984. Transcervical chorionic villus sampling (CVS) was performed in 498 pregnancies. The rate of abnormal pregnancies was 6%, the rate of chromosomal abnormalities (trisomy) in the indication group "maternal age" was 2%. The fetal loss rate (until 28 weeks) was 3.4% (17 cases), the procedure related loss plus the background loss was 2.4% (12 cases). For 92.8% of the patients a diagnosis was available after 1 CVS procedure. Ultimately an antenatal diagnosis was given to 99% of the women through a second CVS procedure or an amniocentesis or a cordocentesis. No maternal complication was observed.

Chorionic Villi Sampling↗
PubMed2004

On-line sample concentration techniques in capillary electrophoresis: velocity gradient techniques and sample concentration techniques for biomolecules.

Methods with a high sensitivity and high separation efficiency are goals in analytical separation techniques. On-line sample concentration techniques in capillary electrophoresis (CE) separations have rapidly grown in popularity over the past few years because they achieve this goal. This review describes the methodology and theory associated with a number of different techniques, including electrokinetic and chromatographic methods. For small molecules, several on-line concentration methods based on velocity gradient techniques are described, in which the electrophoretic velocities of the analyte molecules are manipulated by field amplification, sweeping, and isotachophoretic migration, resulting in the on-line concentration of the analyte zones. In addition, the on-line concentration methods for macromolecules are described, since the techniques used for macromolecules (DNAs and proteins), are different from those for small molecules, with respect to either mechanism or methodology. Recent studies relating to this topic are also discussed, including electrophoretic and chromatographic techniques on capillary or microchip.

DNA↗
PubMed2001

Genome-wide linkage analysis in a general population sample using sigma 2A random effects (SSARs) fitted by Gibbs sampling.

We used variance components analysis to investigate the underlying determinants of the quantitative phenotypes (Q1-Q5) and their interrelationships in replicate 42 of the Genetic Analysis Workshop 12 simulated general population. Variance components models were fitted using Gibbs sampling in WinBUGS v1.3. Sigma-squared-A-random-effects (SSARs) were estimated for each phenotype, and were used as derived phenotypes in subsequent linkage analyses. Whole-genome, multipoint linkage analyses were based upon a new Haseman-Elston identity-by descent sib-pair method that takes a weighted combination of the trait-sum and trait-difference. The five quantitative traits simulated were closely correlated with each other and with affection status. The whole-genome screen of quantitative traits associated with the simulated complex disease suggested that one or more major loci regulating Q1 localizes to chromosome 2p and that one or more major loci regulating Q5 may localize to chromosome 1p.

Algorithms↗
PubMedDate not supplied

Fetoscopy and fetal blood sampling in the management of a twin pregnancy with 45,X/46,XX amniotic fluid cell mosaicism and a suspected fluid sampling error.

A 37 year-old woman with a twin pregnancy underwent amniocentesis to exclude fetal chromosome abnormality. The results indicated that both fetuses were mosaics, with 45,X and 46,XX, cell lines. Since it was suspected from the ultrasound scan that the twins were dizygotic, the result was questioned. Fetoscopy and fetal blood sampling were performed and karyotyping the fetal lymphocytes confirmed that one twin was indeed a mosaic, 45,X/46,XX, but the other had a normal male chromosome complement. The pregnancy resulted in the birth of a phenotypically normal girl, in whom the 45,X/46,XX mosaicism was confirmed, and a normal boy.

Adult↗
PubMed2006

Reduction of proteins during sample preparation and two-dimensional gel electrophoresis of woody plant samples.

Protein extraction procedure and the reducing agent content (DTT, dithioerythritol, tributyl phosphine and tris (2-carboxyethyl) phosphine (TCEP)) of the sample and rehydration buffers were optimised for European beech leaves and roots and Norway spruce needles. Optimal extraction was achieved with 100 mM DTT for leaves and needles and a mixture of 2 mM TCEP and 50 mM DTT for roots. Performing IEF in buffers containing hydroxyethyldisulphide significantly enhanced the quality of separation for all proteins except for acidic root proteins, which were optimally focused in the same buffer as extracted.

Buffers↗
PubMed1978

Tuberculosis in Kenya: a second national sampling survey of drug resistance and other factors, and a comparison with the prevalence data from the first national sampling survey. An East African and British Medical Research Council Co-operative Investigation.

A survey was carried out in 1974 in the same random sample of 11 of 30 districts in Kenya that were surveyed in 1964, to obtain information on (a) the proportion of patients with pulmonary and with extra-pulmonary tuberculosis, (b) the prevalence of bacteriologically-positive pulmonary tuberculosis, (c) the prevalence of initial and acquired drug resistance, (d) the radiographic extent and type of pulmonary disease, and (e) the changes that had occurred in the 10-year period. Of 1490 patients, 88.5% had pulmonary tuberculosis only, 3.0% had both extra-pulmonary and pulmonary tuberculosis and 8.6% had extra-pulmonary tuberculosis only. Of the 172 patients with extra-pulmonary tuberculosis, 51% had lymph node involvement, 24% bone and joint disease and 9% a pleural effusion. Of the 1362 patients with pulmonary tuberculosis (with or without extra-pulmonary tuberculosis) 94% had no history of previous chemotherapy, fewer than 1% a history of possible and 6% a history of definite previous chemotherapy. (The proportions for the patients with extra-pulmonary tuberculosis only were 94%, 1% and 5% respectively.) A sputum specimen was produced by 1096 (80%) of the patients with pulmonary tuberculosis; 69% of smear results were positive, as were 74% of the culture results. In 2 (0.25%) of the 807 patients with a positive culture the strain was identified as being neither M. tuberculosis nor M. bovis. Of 702 patients with no history of previous chemotherapy and a sensitivity test result available, 10.1% had a strain resistant to isoniazid and/or streptomycin, 7.3% to isoniazid alone, 1.4% to streptomycin alone and 1.4% to both drugs. Of 1133 patients with chest radiographs available and a diagnosis in Kenya of pulmonary tuberculosis, a lung lesion or a pleural effusion was reported at independent assessment in London for 91%. Gross, extensive or moderate disease was present in 73% of the patients and cavitation was present in 72%. The radiographic disease was classified as acute in 31%, mixed-acute in 52%, mixed in 12% and chronic in 5%. The disease in children was usually less extensive, less often cavitated, and more acute than in adults. A comparison of the prevalence data in 1974 with that in 1964 suggested that there was a modest decline in the incidence of tuberculosis but that the characteristics of the registered patients and their disease were very similar in all respects; the disease was just as extensive radiographically and cavitation was, if anything, more common and more extensive in 1974 than in 1964.

Adolescent↗