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At least 1,369 records · Page 76Linked to original sources
PubMed1999

Detection of clonal B cells in microdissected reactive lymphoproliferations: possible diagnostic pitfalls in PCR analysis of immunoglobulin heavy chain gene rearrangement.

AIMS: To evaluate the specificity of standard and fluorescence based (Genescan) polymerase chain reaction (PCR) immunoglobulin heavy chain (IgH) gene rearrangement analysis in complete and microdissected paraffin wax embedded sections from lymphoid proliferations. METHODS: PCR IgH gene rearrangement analysis of whole sections and microdissected fragments (n = 62) from paraffin wax embedded reactive lymph nodes (n = 6) and tonsils (n = 3). Amplificant analysis used both standard methods and automated high resolution fluorescence based quantification and size determination using GENESCAN software. RESULTS: Whole tissue sections were consistently polyclonal in control experiments. IgH gene amplification was successful in 59 of 62 microdissected fragments; only two of 59 showed a polyclonal rearrangement pattern, the remainder being oligoclonal or monoclonal. Reanalysis was possible in 33 samples; six showed reproducible bands on gel analysis and satisfied accepted criteria for monoclonality. Use of high resolution gels with Genescan analysis improved sensitivity and band definition; however, three samples still appeared to be monoclonal. CONCLUSIONS: These results confirm that PCR based IgH gene rearrangement analysis is a sensitive and specific method for demonstrating B cell clonality in whole paraffin wax embedded sections. However, oligoclonal and monoclonal rearrangement patterns are regularly encountered in small tissue fragments from otherwise unremarkable reactive lymphoproliferations, possibly because of preferential priming or detection of local B cell clones. Data from clonal analysis of small, microdissected or lymphocyte poor samples must be evaluated critically. It is recommended that analyses should be run in parallel on at least two tissue specimens. Only reproducible bands present in more than one sample should be considered to be suggestive of neoplasia.

B-Lymphocytes↗
PubMed1980

Dust exposure and mortality in chrysotile mining, 1910-75.

We report a further follow-up of a birth cohort of 11 379 workers exposed to chrysotile. The cohort consisted of 10 939 men and 440 women, born 1891-1920, who had worked for at least a month in the mines and mills of Asbestos and Thetford Mines in Quebec. For all subjects, length of service and estimates of accumulated dust exposure were obtained, with a smoking history for the vast majority. Three methods of analysis, two based on the "man-years" methods, the other a "case-and-multiple-controls" approach, gave results consistent with one another and with previous analyses. By the end of 1975, 4463 men and 84 women had died. Among men, the overall excess mortality, 1926-75 was 2% at Asbestos and 10% at Thetford Mines, much the dustier region. The women, mostly employed at Asbestos, had a standardised mortality ratio (SMR) all causes, 1936-75) of 0.90. Analysis of deaths 20 years or more after first employment showed that in men with short service (less than five years) there was no discernible correlation with dust exposure. Among men employed at least 20 years, there were clear excesses in those exposed to the heaviest dust concentrations. Reanalysis in terms of exposure to age 45 showed definite and consistent trends for SMRs for total mortality, for lung cancer, and for pneumoconiosis to be higher the heavier the exposure. The response to increasing dose was effectively linear for lung cancer and for pneumoconiosis. Lung cancer deaths occurred in non-smokers, and showed a greater increase of incidence with increasing exposure than did lung cancer in smokers, but there was insufficient evidence to distinguish between multiplicative and additive risk models. There were no excess deaths from laryngeal cancer, but a clear association with smoking. Ten men and one woman died from pleural mesothelioma. If the only subjects studied had been the 1904 men with at least 20 years' employment in the lower dust concentrations, averaging 6.6 million particles per cubic foot (or about 20 fibres/cc), excess mortality would not have been considered statistically significant, except for pneumoconiosis. The inability of such a large epidemiological survey to detect increased risk at what, today, are considered unacceptable dust concentrations, and the consequent importance of exposure-response models are therefore emphasised.

Accidents↗
PubMed1989

Further results from a census based mortality study of fertiliser manufacturers.

The results of a further follow up of two cohorts of men identified as manufacturers of fertilisers in the 1961 and 1971 censuses of England and Wales are reported. Both cohorts have now been followed up until 1985 through the National Health Service Central Register. In the 1961 cohort the previous findings are replicated--low mortality from all causes, all cancers, and all circulatory diseases, and no evidence of dose response relation nor excess mortality from cancer at any site. In the 1971 cohort there remain more deaths from cancer than expected but none of the observed deaths from individual cancers differs significantly from expectation by comparison with national mortality rates or rates for other employed men. Evidence of an association between cancer mortality and frequency of exposure to nitrate containing dust is strengthened in the reanalysis of the 1971 cohort after longer follow up, but a negative trend, significant for digestive organ cancers, is observed in the analysis by product type in which manufacturers of straight nitrogen and compound fertilisers might have been expected to be most at risk. Failure to find specifically any excess mortality from gastric cancer and the contradictory dose response relations, weigh against the notion that the nonsignificant excesses of cancers in the 1971 cohort are related to nitrate exposure.

Air Pollutants, Occupational↗
PubMed1983

Silicosis in surface coalmine drillers.

Surface coalminers are generally thought to be at minimal risk of developing pneumoconiosis. Biopsy-proved silicoproteinosis was found in a 34-year-old surface coalmine driller, and two of nine other drill crew members who worked for the same company had chest radiographic findings compatible with simple silicosis. Reanalysis of data from a previous United States Public Health Service survey of surface coalminers, after exclusion of those with underground mining experience, showed that 38% of the cases of pneumoconiosis occurred in drill crew members, a group comprising only 11% of the study population. On the basis of these data surface coalmine drillers appear to have an increased risk of developing occupational lung disease.

Adult↗
PubMed1994

Mitochondrial DNA diversity in the pea aphid Acyrthosiphon pisum.

The pea aphid Acyrthosiphon pisum has been established in North America for at least a century and occurs on a broad range of host plants. Despite its importance as a crop pest, there is little understanding of the genetic structure of its populations or the extent of genetic divergence associated with different host plant utilization. This study examined the extent of mitochondrial DNA (mtDNA) diversity among 35 clones of pea aphids from alfalfa. Polymorphisms were detected at only 2 of 126 restriction sites, suggesting the same impoverished level of genetic diversity found in prior allozyme studies. However, length variation was common and apparently arose as a result of tandem repeats in two regions of the mtDNA molecule. Region 1 occurred in proximity to the control region of the molecule, while region 2 was close to a cluster of tRNA genes flanking the NAD-dehydrogenase subunit 3 gene on the opposite side of the mtDNA molecule. Each of the aphid clones was homoplasmic for a single length variant in region 1, which varied with respect to the number of copies of a 120-bp repeat. By contrast, one-third of the clones were heteroplasmic at region 2, where they possessed a variable number of copies of a 210-bp repeat. Reanalysis of clones after 30 generations of parthenogenetic reproduction established the stability of length variants over this interval, suggesting their value in studies of the genetic structure of aphid populations.

Animals↗
PubMed1995

Analysis of the distal 5' region of the human CYP17 gene.

In order to search for additional regulatory elements in the human CYP17 (steroid 17 alpha-hydroxylase) gene and to compare it with potential regulatory elements in bovine CYP17 genes, 3.5 kb of 5' flanking region of CYP17 was cloned and analyzed. The newly acquired sequence was shown to be a highly defective copy of the human endogenous retrovirus HERV-K family. This retroviral sequence was itself interrupted by a novel element, a low copy number repeat occurring about 20 times in the human genome, including a known copy in the human catechol-O-methyltransferase gene. A reanalysis of the entire 5' flanking region of human CYP17 indicates that only the 300 bp immediately distal to the promoter is of unique sequence; other regulatory sequences, including any that are similar to the upstream region of the bovine genes, are unlikely to occur within 5.5 kb of the promoter.

Aldehyde-Lyases↗
PubMed1996

Evolution of ticks.

Evolutionary patterns in ticks have traditionally been cast in terms of host associations. Largely untested assumptions of cospeciation and observations of current host associations are used to estimate the age of different taxa. Several recent phylogenetic studies of supraspecific relationships in ticks, based on both morphological and DNA-sequence data, allow the first rigorous testing of these assumptions. Reanalysis of patterns of tick-host associations suggests that the perception of host specificity in ticks may be an artifact of incomplete sampling. An analysis of tick-host and -habitat associations and biogeographical patterns, in the context of the newly derived phylogenies, suggests that much of the existing host-association patterns may be explained as artifacts of biogeography and ecological specificity.

Animals↗
PubMedDate not supplied

Informatics in Radiology (infoRAD): Magnetic Resonance Imaging Workbench: analysis and visualization of dynamic contrast-enhanced MR imaging data.

Magnetic Resonance Imaging Workbench (MRIW) allows analysis of T1- and T2*-weighted dynamic contrast-enhanced magnetic resonance imaging data sets to extract tissue permeability and perfusion characteristics by using standard pharmacokinetic models. Parametric maps are calculated from individual pixel enhancement curves in regions of interest (ROIs) and displayed as color overlays on the anatomic images. User-defined ROIs can be saved to ensure consistency of later reanalysis. Individual parametric maps are visualized together with user-selected parameter time-series plots. The following selections are available: overall ROI enhancement curve and fit, histogram, and individual pixel enhancement curve and fit. Summary data (transfer constant, leakage space, rate constant, integrated area under the gadolinium curve after 60 seconds, relative blood volume, relative blood flow, and mean transit time) may be exported to permanent storage along with per-pixel results for statistical analysis. Numerical values for parameters are displayed below the plot for easy reference. The dynamic range of plots and parametric map overlays is interactively adjustable. Viewing individual enhancement curves and parametric maps allows radiologists to investigate the heterogeneity of contrast agent kinetics for lesion characterization and to scrutinize serial changes in response to therapy. MRIW is written in IDL, enabling it to be used on a variety of computer systems.

Computer Graphics↗
PubMed1980

Transport of amino acids in whole blood and plasma of sheep.

Comparisons of amino acid transport in both whole blood and plasma were made across the portal-drained viscera, liver, kidneys, and hindquarters in sheep. Lyophilized samples could be stored at -20 degrees C for up to 17 wk with little or no changes observed on reanalysis. Only glutamine, taurine, and serine showed any loss (18, 23, and 16%) over a 3.5-yr period. However, there was no concomitant rise in glutamate over the same period, suggesting that glutamate does not simply deamidate. There were no differences in arterial concentrations of alanine, citrulline, isoleucine, and valine between whole blood and plasma. However, glutamate, asparagine, glycine, serine, threonine, taurine, ornithine, leucine, lysine, phenylalanine, and tyrosine were higher in whole blood compared to plasma, and glutamine and arginine were lower. Whole blood and plasma fluxes for all amino acids were positively correlated, and there were no differences in their regression lines among tissues. Plasma, however, underestimated amino acid transport glutamine, glutamate, and taurine at greater rates than plasma. It is concluded that blood cellular transport, per unit volume, was always concomitant to and usually at the same rate as plasma transport over all tissues measured. Plasma therefore reflects amino acid transport but underestimates total transport to about the extent of the packed cell volume and in cases of glutamine, glutamate, and taurine, perhaps even more.

Amino Acids↗
PubMed1987

Metabolites of 2-deoxyglucose in rat brain at 12-24 h: bounds on kinetic constants.

Activities of 2-deoxy-D-glucose and its metabolites in rat brain were examined at 12, 16, 20, and 24 h after intraperitoneal injection of 14C-labeled 2-deoxy-D-glucose. Plasma radioactivity was monitored for 2 h before each of these determinations. As proportion of total brain radioactivity, 2-deoxy-D-glucose decreased monotonically from the unexpectedly high value of 22% at 12 h to 11% at 24 h after injection, 2-deoxy-D-glucose 6-phosphate decreased monotonically from 69% at 12 h to 23% at 24 h, and unphosphorylated products (of high and low molecular weight) increased from 10% at 12 h to 64% at 24 h. The data were analyzed in terms of a four-compartment model. Secure lower and upper bounds on the rate constant, k4*, for the dephosphorylation of 2-deoxy-D-glucose 6-phosphate were established: k4* was at least 0.0158 +/- 0.0014 . min-1 and at most 0.0385 +/- 0.0037 . min-1. If k4* is constant in time, then appreciable dephosphorylation occurs within the 45-min experimental period commonly used in the standard 2-deoxy-D-glucose method for estimating local cerebral glucose utilization. The possibility that the effective k4* is lower at such early times is reviewed in the light of a reanalysis of previously published data. Implications of these results for the 2-deoxy-D-glucose method are discussed from the points of view of numerical analysis and capillary heterogeneity.

Animals↗
PubMed1995

Validation of 1- and 2-mm transit-time ultrasound flow probes on mesenteric artery and aorta of rats.

The aim of this investigation was to validate and calibrate the 1- and 2-mm transit-time ultrasound, perivascular flow probes on the superior mesenteric artery and aorta of the rat by using an in vivo and in situ calibration system. The baseline blood flows measured by the flowmeter zero-flow function and the true-zero flow measurement, after complete occlusion of the vessels, were not different. The probes were then calibrated, in situ, by timed-volume measurements with a blood/saline pump-perfused circuit. The relationship between measured flow and true flow was linear for both probes. The slope of the 1-mm probe data was not significantly different from the line of identity, whereas the 2-mm probe data slightly overestimated the true flow (slope = 1.2, y-intercept = -3.2 ml/min). The slope of the middle region of the 2-mm probe data, however, was not significantly different from the line of identity, suggesting that the 2-mm probe has a window of accuracy over this range of flows. Progressive elimination of the low and high data points varying the most from the line of identity and reanalysis of the data revealed that the window of accuracy for the 2-mm probe, under our experimental conditions, was between 10.4 and 45.1 ml/min.

Animals↗
PubMed1992

Renal expression of the gene for atrial natriuretic factor.

To date, atrial natriuretic factor (ANF) mRNA has eluded detection in the mammalian kidney, although we and others have identified ANF protein in the kidney using immunohistochemical and immunoassay techniques. Furthermore, we have demonstrated the synthesis and secretion of the ANF prohormone in the distal cortical nephron of the intact rat kidney and from rat primary cultured renal distal cortical tubular epithelial cells. In the present study, we show that the ANF gene is expressed in the kidney. Amplification of RNA isolated from rat distal cortical tubular epithelial cultures using ANF specific primers produced a 213-bp fragment that specifically hybridized to a 32P-labeled ANF cDNA. We had previously demonstrated these cultures to be enriched for the renal ANF synthetic and secretory cell type. However, we were unable to detect an ANF gene transcript in total rat kidney RNA using the above-mentioned polymerase chain reaction (PCR) conditions. Reanalysis of normal rat kidney PCR products by a second round of PCR amplification using nested primers successfully identified ANF mRNA. Similar to cultured kidney epithelial cells, normal rat kidney expresses ANF mRNA, but at a very low abundance, thus necessitating two rounds of PCR amplification. Further characterization of rat cortical distal tubular epithelia poly(A)+ RNA by Northern analysis revealed two ANF gene transcripts. A 1.0-kb message that comigrated with rat atrial ANF mRNA, and a second larger 1.4-kb transcript. These studies further substantiate the synthesis of ANF in the mammalian kidney. Unlike the mammalian heart, the kidney contains two ANF gene transcripts.

Animals↗
PubMed1979

Estimating central and peripheral respiratory resistance: an alternative analysis.

Pimmel et al (J. Appl. Physiol.: Respirat. Environ. Exercise Physiol. 45: 375--380, 1978) recently presented an analysis of the frequency dependence of respiratory resistance (Rrs) based on a simple electrical analog of the respiratory system that allows estimation of the central (Rc) and peripheral (Rp) components of Rrs. The method by which they determine these parameters from the experimental data is based on a number of unproven assumptions. Using the same electrical analog, we present an analysis that allows calculation of these parameters, as well as the corner frequency of the network (f1), without need for similar assumptions. Our technique is based on fitting the resistances (RTh) measured over a range of frequencies (f) to the exact solution of the network given by RTh = Rc + Rpf1(2)/f2 + f1(2)). Using the transformation X = 1/(f2 + f1(2), the equation becomes a linear relationship between RTh and X allowing the resistances to be determined by linear regression. Reanalysis of Pimmel et al.'s data demonstrated that the assumptions of a constant f1, and the equivalence of RTh at 0 Hz to RTh at 1 Hz in invalid under certain conditions. Thus, if one is to use the electrical analog to partition Rrs into its central and peripheral components, one should use the analytic approach suggested here that does not rely on these assumptions.

Airway Resistance↗
PubMed2006

Coherent spontaneous activity identifies a hippocampal-parietal memory network.

Despite traditional theories emphasizing parietal contributions to spatial attention and sensory-motor integration, functional MRI (fMRI) experiments in normal subjects suggest that specific regions within parietal cortex may also participate in episodic memory. Here we examined correlations in spontaneous blood-oxygenation-level-dependent (BOLD) signal fluctuations in a resting state to identify the network associated with the hippocampal formation (HF) and determine whether parietal regions were elements of that network. In the absence of task, stimuli, or explicit mnemonic demands, robust correlations were observed between activity in the HF and several parietal regions (including precuneus, posterior cingulate, retrosplenial cortex, and bilateral inferior parietal lobule). These HF-correlated regions in parietal cortex were spatially distinct from those correlated with the motion-sensitive MT+ complex. Reanalysis of event-related fMRI studies of recognition memory showed that the regions spontaneously correlated with the HF (but not MT+) were also modulated during directed recollection. These regions showed greater activity to successfully recollected items as compared with other trial types. Together, these results associate specific regions of parietal cortex that are sensitive to successful recollection with the HF.

Adolescent↗
PubMed2002

Low-frequency oscillations (<0.3 Hz) in the electromyographic (EMG) activity of the human trapezius muscle during sleep.

The surface electromyographic (EMG) signal from right and left trapezius muscles and the heart rate were recorded over 24 h in 27 healthy female subjects. The root-mean-square (RMS) value of the surface EMG signals and the heartbeat interval time series were calculated with a time resolution of 0.2 s. The EMG activity during sleep showed long periods with stable mean amplitude, modulated by rhythmic components in the frequency range 0.05-0.2 Hz. The ratio between the amplitude of the oscillatory components and the mean amplitude of the EMG signal was approximately constant over the range within which the phenomenon was observed, corresponding to a peak-to-peak oscillatory amplitude of approximately 10% of the mean amplitude. The duration of the periods with stable mean amplitude ranged from a few minutes to approximately 1 h, usually interrupted by a sudden change in the activity level or by cessation of the muscle activity. Right and left trapezius muscles presented the same pattern of FM. In supplementary experiments, rhythmic muscle activity pattern was also demonstrated in the upper extremity muscles of deltoid, biceps, and forearm flexor muscles. There was no apparent association between the rhythmic components in the muscle activity pattern and the heart rate variability. To our knowledge, this is the first time that the above-described pattern of EMG activity during sleep is documented. On reanalysis of earlier recorded trapezius motor unit firing pattern in experiments on awake subjects in a situation with mental stress, low-FM of firing with similar frequency content was detected. Possible sources of rhythmic excitation of trapezius motoneurons include slow-wave cortical oscillations represented in descending cortico-spinal pathways, and/or activation by monoaminergic pathways originating in the brain stem reticular formation. The analysis of muscle activity patterns may provide an important new tool to study neural mechanisms in human sleep.

Adult↗
PubMed2006

Diet, cancer, and the lipidome.

The potential for dietary fat to interfere with the development of breast cancer by delaying its occurrence makes the identification of defined molecules a mandatory step in cancer prevention. In order to circumvent the limitations and/or bias of dietary exposure assessment tools, biomarkers of past lipid intake such as the fatty acid composition of white adipose tissue have been used. When considered separately, candidate fatty acids identified as favorable on the basis of their association with breast cancer risk have usually led to inconsistent results in animal intervention studies. This inconsistency indicates that any approach based on a single fatty acid should be abandoned for an integrated view over the complex lipid interactions which finally determines the lipidome, the lipid profile that is found in individuals. This article presents a reappraisal of the role of the lipid profile through a comprehensive reanalysis of adipose tissue fatty acid composition obtained in patients with benign or malignant breast tumors as well as in experimental animals during dietary interventions. Rather than a single fatty acid, a composite indicator combining elevated monounsaturates and low omega6/omega3 fatty acid ratio was associated with breast cancer protection. This lipidome may become the template for identifying breast cancer risk related to diet, and for designing proper dietary modifications to delay the occurrence of breast cancer, although the universality of the findings cannot be assessed from a single study.

Adipose Tissue↗
PubMed1998

The role of perception in the sound change of velar palatalization.

Voiceless velar stops may become palatoalveolar affricates before front vowels. This sound change is not only one of the most common types of palatalization, but is a very common sound change in the world's languages. Nevertheless, we do not have an adequate understanding of how this sound change takes place. Three experiments reported here test the hypothesis that velar palatalization is the result of listeners' on-line perceptual reanalysis of fast rate speech. It is shown that velars before front vowels are both acoustically and perceptually similar to palatoalveolars. This supports the proposal that velar palatalization is perceptually conditioned.

Adult↗
PubMed2000

Comparison of body composition analysis methods in clinical routine.

BACKGROUND: Skinfold thickness (SFT) and bioelectrical impedance (BIA) are readily available and commonly used techniques in patient monitoring for body composition analysis (BCA) in clinical practise. Another one, dual-energy X-ray absorptiometry (DEXA) method became popular in body composition analysis (BCA) in recent years. Its results have been reported to be quite accurate and precise, in comparison with in vivo or in vitro multiple component reference methods. The aim of the present study was to assess the degree of agreement between SFT and DEXA, and BIA and DEXA methods, in obese and nonobese patients. METHODS: Body fat mass (FM) was measured in 16 nonobese (mean body mass index; BMI = 22.2 +/- 2.2 kg/m(2)) and in 21 obese (BMI = 34.5 +/- 6.1 kg/m(2)) women with DEXA, SFT, and BIA in the same morning. RESULTS: Mean (+/- SD) FM (kg) was 16.3 +/- 5.5, 15.0 +/- 5.1, 14.7 +/- 4.9 in nonobese subjects and 38.8 +/- 10.1, 36.3 +/- 10.0, 37.1 +/- 12.0 in obese patients, by DEXA, SFT and BIA, respectively. Comparison of the DEXA-BIA and DEXA-STF methods showed high correlation in regression line analysis in nonobese subjects as, r(2) = 0.93 and 0.89, respectively. Regression coefficients were 0.84 and 0.75 in obese patients. However, reanalysis of the data by the Bland and Altman method revealed an obvious lack of agreement between the DEXA-BIA and DEXA-SFT methods in obese patients. In addition, FM was underestimated by BIA and SFT as compared to DEXA in both of the study groups. Besides, better precision was obtained by DEXA method among the others. CONCLUSION: The SFT or BIA method would be preferred to monitor BCA in non-obese subjects in clinical routine. However, DEXA should be considered as the method of choice in obese patient monitoring, since reproducibility gains special importance, other than the accuracy in the context.

Absorptiometry, Photon↗