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PubMedDate not supplied

Biometric analysis of phenotypic characters of potato shoot-tips recovered from tissue culture, dimethyl sulphoxide treatment and cryopreservation.

A biometric approach partly involving principal component analysis has been used to examine the changes in phenotypic characters of shoot-tip derived potato plants recovered from tissue culture, dimethyl sulphoxide (DMSO) and cryopreservation in comparison with field-grown tuber-derived plants. There were significant differences in the quantitative characters height and tuber weight in the cryopreserved plants compared to those derived from DMSO treatment and tissue culture. These three experimental groups were shown to significantly differ from field-grown plants in the characters, tuber weight followed by height and length of petiole. The use of biometrics as an analytical approach in genetic stability assessments of plants recovered from cryopreservation to relatively small sample sizes is discussed.

Biometry↗
PubMed2005

Measuring socio-economic inequalities in the presentation of injuries to a paediatric A&E department: the importance of an epidemiological approach.

OBJECTIVES: To contrast the socio-economic pattern of childhood injuries presenting to a paediatric accident and emergency (A&E) department revealed by using both a numerator-based and a denominator-based approach to the analysis of injury surveillance data. METHODS: Injury surveillance data collected during 1997-1998 at a Glasgow children's hospital A&E department were analysed. Socio-economic status was measured using Carstairs' deprivation index. Data from West Glasgow postcode sectors only were analysed in order to optimize epidemiological validity. Socio-economic patterning of injury was investigated in two ways-numerator-based and denominator-based. RESULTS: A total of 12,762 children (0-14 years) living in West Glasgow attended the A&E department of the Royal Hospital for Sick Children over the study period. Both analytical approaches showed a clear and statistically significant excess of injury presentations in children from more deprived postcode sectors, but the variation appeared much greater in the numerator-based rather than the denominator-based approach. In regression analysis, however, only the denominator-derived rates showed a statistically significant linear trend across deprivation categories. CONCLUSION: The most appropriate and accurate means of measuring the extent of socio-economic (and other) inequalities in injury risk is to adopt a population-based rather than numerator-based perspective on the data collected by injury surveillance systems.

Adolescent↗
PubMed1996

Epidemiology of multiple sclerosis.

The inhomogeneous distribution of MS may represent an important clue about the cause of the disease. The prevalence of MS appears to be increasing in many regions of the world, although it is likely that in a majority of regions surveyed, this increase is attributable to differences in ascertainment over the relatively short period that MS has been surveyed worldwide, which is almost exclusively the last 50 years. MS occurs most frequently in regions populated by northern Europeans, and in these areas, it is much more common in the northern European population than in the indigenous populations. MS occurs in relatives of MS patients at a rate 10- to 50-fold greater than in the general population. On average, the absolute risk to a first-degree relative of an MS patient is 2% to 5%, depending on the exact degree of relatedness. Although the mode of transmission is not certain, a multigenic pattern best fits the observed pattern of transmission. A majority of monozygotic twins are discordant for MS, indicating that a major component of MS susceptibility is environmentally determined, although recent observations in adopted relatives suggest that this risk is not transmissible. Rare epidemics of MS involving small numbers of individuals in geographically isolated regions have been reported. A number of migrant studies suggest that the risk of acquiring MS may be altered by migration, although some also support genetic factors. Analytic approaches to address the role of various risk factors include ecologic studies, case-control studies, and cohort studies. Ecologic studies are best suited for addressing risk factors that influence overall population risk, whereas case-control studies are best suited for addressing risk factors that pertain to individuals within a population. If a risk factor is distributed homogeneously in a given population, a case-control study is insensitive to its effect. Improved methodology to diminish the biases inherent in case-control studies and identification of other important risk factors from basic scientific studies undoubtedly will be important for analytic epidemiologic studies of the future. Furthermore, analysis of highly informative populations, such as discordant identical twins and adoptive siblings of MS patients, likely will improve the specificity of case-control studies by minimizing the vast number of potential differences between cases and controls.

Case-Control Studies↗
PubMed2003

Knowledge of the Bacillus subtilis genome: impacts on fundamental science and biotechnology.

The advent of genomics has greatly influenced fundamental and applied microbiology. This has become paradigmatic in the case of Bacillus subtilis, a primary model bacterium for research and biotechnology. Indeed, mining its genome has provided more fruitful information than classical approaches would have yielded in a longer period of time. Through advanced analysis of its genome and transcriptome, fundamental discoveries dealing with the informational architecture of the B. subtilis chromosome, as well as with the elucidation of its pathway-level regulation of gene expression, have been achieved. The possibility of performing a complete metabolic manipulation of the secretory pathway of Bacillus is promising important biotechnological fallouts. Similar emphasis exists for the possibility of controlling the cell in the formation of biofilms with specific physical and chemical characteristics. At the theoretical level, the new concept of genetic superinformation has been formulated and its analytical approach implemented, while the understanding of the minimal genetic requirements for the existence of a reproducing bacterial cell is being tackled. In summary, the impact of the B. subtilis genome has philosophically revolutionised the way that basic knowledge is translated into applied microbiology and biotechnology, making this bacterium the workhorse of post-genomic microbiology.

Bacillus subtilis↗
PubMed2004

Speciation analysis of mercury by solid-phase microextraction and multicapillary gas chromatography hyphenated to inductively coupled plasma-time-of-flight-mass spectrometry.

This paper reports the development of an analytical approach for speciation analysis of mercury at ultra-trace levels on the basis of solid-phase microextraction and multicapillary gas chromatography hyphenated to inductively coupled plasma-time-of-flight mass spectrometry. Headspace solid-phase microextraction with a carboxen/polydimethylsyloxane fiber is used for extraction/preconcentration of mercury species after derivatization with sodium tetraethylborate and subsequent volatilization. Isothermal separation of methylmercury (MeHg), inorganic mercury (Hg2+) and propylmercury (PrHg) used as internal standard is achieved within a chromatographic run below 45 s without the introduction of spectral skew. Method detection limits (3 x standard deviation criteria) calculated for 10 successive injections of the analytical reagent blank are 0.027 pg g(-1) (as metal) for MeHg and 0.27 pg g(-1) for Hg2+. The repeatability (R.S.D., %) is 3.3% for MeHg and 3.8% for Hg2+ for 10 successive injections of a standard mixture of 10pg. The method accuracy for MeHg and total mercury is validated through the analysis of marine and estuarine sediment reference materials. A comparison of the sediment data with those obtained by a purge-and-trap injection (PTI) method is also addressed. The analytical procedure is illustrated with some results for the ultra-trace level analysis of ice from Antarctica for which the accuracy is assessed by spike recovery experiments.

Gas Chromatography-Mass Spectrometry↗
PubMed1997

A novel approach to assess changes in endocrine secretion: analysis of GnRH antagonist (Nal-Glu) suppression of gonadotropin release in ovariectomized ewes.

Circulating hormone levels reflect the outcome of multiple feedback systems. A method to accurately assess the dynamics of hormonal changes in samples collected at infrequent intervals and compare these dynamic processes among treatment groups is presented. In this approach, a smooth curve is fitted to each time series of concentrations produced in an experiment, the curves are summarized by numerical measurements, and the measurements are subjected to statistical analysis. The method is demonstrated on data from an experiment that explores the differential effects of a competitive GnRH receptor antagonist (Nal-Glu) on circulating levels of LH and FSH. In this experiment, six adult ovariectomized Suffolk ewes were treated with one of three doses of Nal-Glu using a crossover design. LH and FSH concentrations were determined in hourly samples of jugular blood for 24 h after treatment. Applying the analytical approach, we observed differential effects of increasing concentrations of Nal-Glu on circulating LH and FSH concentrations. The magnitude of LH suppression was similar from dose to dose, while the duration of LH suppression was dose-dependent. In contrast, all doses of Nal-Glu elicited similar effects on the amplitude, duration and time to recovery of FSH suppression. Studies conducted in vitro utilizing dispersed ovine pituitary cells in culture demonstrated that the differential effects of Nal-Glu on FSH and LH secretion were not the outcome of differential sensitivity of FSH and LH to GnRH. The differential effects of Nal-Glu on circulating LH and FSH concentrations may be due to a number of factors, including other releasing or release-inhibiting hormones, paracrine modulators involved in selective regulation of FSH, and/or differences in clearances.

Animals↗
PubMed1994

Estimated contribution of coronary artery bypass graft surgery to the decline in coronary heart disease mortality: the Minnesota Heart Survey.

OBJECTIVES: This study assessed the possible contribution of coronary artery bypass graft surgery to the decline in coronary heart disease mortality in the Minneapolis-St. Paul metropolitan area population between 1970 and 1984. BACKGROUND: Coronary artery bypass graft surgery is a major contemporary therapeutic approach for coronary heart disease. Its use has increased over the past two decades because it provides relief of symptoms and, in certain circumstances, prolongs life. During the period that age-adjusted coronary heart disease mortality has decreased, the use of coronary artery bypass graft surgery has increased dramatically, suggesting a relation. METHODS: All 30- to 74-year old Minneapolis-St. Paul area residents undergoing coronary artery bypass graft surgery between 1970 and 1984 (9,548 patients) were registered; their medical records were abstracted; and their survival was ascertained. These data were used in a medical survival probability model using a multivariate analytical approach developed from registries of patients treated medically. The model assumed that coronary artery bypass graft surgery was not available. Two annual mortality rates were compared: the observed Minneapolis-St. Paul annual coronary heart disease mortality rate and the modeled annual coronary heart disease mortality rate. The difference between these rates was the estimated contribution of coronary artery bypass graft surgery to the decline in coronary heart disease mortality rates. RESULTS: Between 1970 and 1984, the estimated surgical contribution increased from 0.2% (increased mortality) to +6.6% of the annual decrease in Minneapolis-St. Paul coronary heart disease mortality. CONCLUSIONS: Between 1970 and 1984, the contribution of coronary artery bypass graft surgery to the decline in coronary heart disease mortality, although small, gradually increased. This change appeared to be related to an increased frequency of coronary artery bypass graft surgery, improved operative mortality and changes in the clinical mix of surgical patients.

Adult↗
PubMed1999

International standards for the assessment of the risk of thermal strain on clothed workers in hot environments.

The International Standards Organisation (ISO) has produced an integrated series of international standards for the assessment of human responses to thermal environments. They include standards for the assessment of thermal comfort, heat stress and cold stress and many have been adopted as European and British standards. This paper describes the series of standards and in particular those concerned with the assessment of risk in hot environments. A three tier approach is taken which involves a simple thermal index that can be used for monitoring and control of hot environments (ISO 7243), a rational approach which involves an analysis of the heat exchange between a worker and his or her environment (ISO 7933) and a standard that describes the principles of physiological measurement which can be used in the establishment of personal monitoring systems of workers exposed to hot environments (ISO 9886). The standards are self-contained and can be used independently. In any comprehensive assessment however they would be used in conjunction. The simple index provides a first stage analysis and can confirm whether or not there is likely to be unacceptable thermal strain. Where a more detailed analysis is required then ISO 7933 provides an analytical method that can provide a more extensive assessment and interpretation leading to recommendations for improvement to the working environment. Where a method needs to be confirmed, or conditions are beyond the scope of ISO 7243 and ISO 7933, then ISO 9886 provides guidance on physiological measurement and interpretation. This would be used in extreme environments where individual responses are required to ensure health and safety or, in the case where personal protective equipment (PPE) is worn, which is beyond the scope of ISO 7243 and ISO 7933. The ISO system therefore covers almost all exposures to hot environments. It would be useful however to extend the scope of the standards that provide a simple index or analytical approach. This paper describes the current standards and their scope and forms the basis and background for descriptions of proposed extensions to the scope of the standards described in other papers in this special issue.

Acclimatization↗
PubMed1995

Small changes in outpatients lupus activity are better detected by clinical instruments than by laboratory tests.

OBJECTIVE: To evaluate and compare responsiveness of laboratory and clinical measures over 4 months in outpatient systemic lupus erythematosus (SLE). METHODS: We studied 23 patients with SLE at monthly intervals during 4 mo and collected demographic data, prednisone dose, global patient and physician assessment of disease activity on 10 cm visual analog scales (VAS), scores on 3 clinical measures of lupus disease activity [SLE disease activity index (SLEDAI), SLE activity measure (SLAM), lupus activity index (LAI)], and results of 5 routine laboratory tests [erythrocyte sedimentation rate (ESR), anti-dsDNA, C3, C4, circulating immune complexes]. We calculated correlations between a particular measure and our gold standard (physician's VAS) for individual patients and pooled this information using a novel application of the meta-analytic approach. RESULTS: The range of disease activity by patient and physician VAS varied from inactive to moderately active> Change in patient global assessment and all 3 clinical measures showed significant positive correlations with change in physician VAS (p < 0.05). Change in ESR, anti-dsDNA, or level of C3, C4, or circulating immune complexes did not correlate with change in physician VAS. CONCLUSION: Clinical measures of disease activity in SLE are more responsive to small changes than traditional laboratory tests. All 3 clinical measures appeared to perform equally well. At least one SLE disease activity measure should be used in SLE trials. The new analytic method will likely be of value in similar evaluations of responsiveness in other diseases.

Adult↗
PubMed2026

Toward a unified approach: Considerations for bioinformatic and sequencing activities & data in wastewater surveillance of biologic public health threats.

Genomic technologies such as PCR and next-generation sequencing (NGS) have greatly advanced public health surveillance, especially during COVID-19, by enabling detailed tracking of pathogen spread, origins, and variants. While PCR is vital for targeted detection, falling NGS costs have made large-scale, high-throughput sequencing more feasible, supporting broader pathogen monitoring-including the detection of vaccine escape variants and new strains. Applying NGS to wastewater offers valuable population-level insights but faces challenges such as variable sample complexity, the need for skilled staff, suitable platforms, and robust IT infrastructure. Although there are currently a lot of efforts towards defining guidelines for sampling, analysis, and integrating wastewater data into public health policy, such as the recently published International Cookbook for Wastewater Practitioners, they often lack universal applicability, emphasizing the analytical approaches in favour of the NGS-based approaches. However, standardising protocols for sampling, sequencing, and analysis is crucial to ensure reliable, comparable data across surveillance systems worldwide. Pilot studies and continuous refinement are recommended to overcome implementation hurdles and fully realise the benefits of NGS in wastewater surveillance. This work attempts to outline these challenges and opportunities across the entire wastewater surveillance workflow, from data generation to reporting, and provide some concrete suggestions and considerations across the spectrum of activities. We further highlight that the infrastructure, funding and government-policy context in which surveillance operates acts as an enabling condition for these activities, and that technical standardisation alone is unlikely to deliver durable, comparable surveillance in its absence.

considerations↗
PubMed1989

Insight into the transfer function, gain, and oscillation onset for the pupil light reflex using nonlinear delay-differential equations.

Analogies are drawn between a physiologically relevant nonlinear delay-differential equation (DDE) model for the pupil light reflex and servo control analytic approaches. This DDE is shown to be consistent with the measured open loop transfer function and hence physiological insight can be obtained into the gain of the reflex and its properties. A Hopf bifurcation analysis of the DDE shows that a limit cycle oscillation in pupil area occurs when the first mode of the characteristic equation becomes unstable. Its period agrees well with experimental measurements. Beyond the point of instability onset, more modes become unstable corresponding to multiple encirclings of (-1, 0) on the Nyquist plot. These modes primarily influence the shape of the oscillation. Techniques from dynamical systems theory, e.g. bifurcation analysis, can augment servo control analytic methods for the study of oscillations produced by nonlinear neural feedback mechanisms.

Blinking↗
PubMed1994

Assays of oxidative DNA damage biomarkers 8-oxo-2'-deoxyguanosine and 8-oxoguanine in nuclear DNA and biological fluids by high-performance liquid chromatography with electrochemical detection.

High-performance liquid chromatography with electrochemical detection is a highly sensitive and selective method for detecting oxo8dG and oxo8Gua, biomarkers of oxidative DNA damage. When employed together with the DNA isolation and monoclonal antibody-based immunoaffinity purification methods described, oxo8dG and oxo8Gua in DNA and urine can be readily detected and quantitated, offering a powerful approach for assessing oxidative DNA damage in vivo. Application of the technique to the detection of oxo8dG from DNA permits quantitation of the steady-state levels of this oxidatively modified deoxynucleoside and overcomes the detection problems associated with the extremely low levels present in DNA. In addition, the selectivity gained by this detection method eliminates the problem of separating the signal for oxo8dG from those of normal deoxynucleosides. The quantitation of oxo8dG and oxo8Gua in biological fluids is noninvasive and complements the measurement of oxo8dG in DNA by estimating the rate of oxidative DNA damage occurring within the body or in a population of cells. This analytical approach may allow one to estimate oxidative DNA damage in an animal or individual exposed to prooxidant conditions associated with lifestyle, genetic predisposition, degenerative diseases, or environmental toxins. Furthermore, these assays may allow one to assess the potentially beneficial effects of intervention strategies that protect DNA from such damage.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2003

Atomic force microscopy evaluation of aqueous interfaces of immobilized hyaluronan.

Hyaluronan (HA) was immobilized on aminated glass surfaces in three different ways: by simple ionic interaction and by covalent linking at low density and at full density. In agreement with previous reports, in vitro experiments show that the outcome of fibroblast adhesion tests is markedly affected by the details of the coupling procedure, suggesting that different interfacial forces are operating at the aqueous/HA interface in the three cases investigated. The interfacial properties of the HA-coated surfaces were probed by force-distance curves obtained with the atomic force microscope (AFM). This approach readily shows significant differences among the tested samples, which are directly related to the coupling strategy and to results of cell adhesion tests. In particular, the range of interaction between the tip and the surface is much lower when HA is covalently linked than when it is ionically coupled, suggesting a more compact surface structure in the former case. Increasing HA surface density minimizes the interaction force between the surface and the AFM tip, likely reflecting more complete shielding by the HA chains of the underlying substrate. In summary, these measurements clearly show the different nature of the aqueous interfaces tested, and underline the role of this analytical approach in the development and control of finely tuned biomaterial surfaces.

Animals↗
PubMed1996

Time-dependent solutions for a cable model of an olfactory receptor neuron.

A mathematical model for an olfactory receptor neuron is investigated. The physiological and anatomical background required for the construction of a mathematical model are explained. The model, which has been described previously, has three components, including the sensory dendrite on which are found the receptor proteins themselves, and others consisting of a passive cable leading to a trigger zone and axon. In the present paper, we pursue an analytical approach for determining the change in time of the receptor potential in the important case of a subthreshold square pulse of odorant stimulation delivered uniformly at the sensory dendrite. Then, the input current increases in time to its asymptotic value. This latter condition means that we can use a Green's function approach in order to obtain accurate representations for the solution for the entire length of the nerve cell. In the case of finite cables the solution is obtained as an infinite series which is shown to converge and can be easily used to find the depolarization at all space and time points of interest. A steady-state result is obtained directly by solving the relevant ordinary differential equation. For a semi-infinite cable an explicit expression is found for the voltage as a function of time and space variables involving a single integral. However, the exact expression follows from this for the steady-state result. The analytical results obtained are compared to numerical solutions and employed to investigate the effect of varying the position of the trigger zone and the electronic length of the neuron.

Humans↗
PubMed1994

Diagnostic concordance of substance use disorders in DSM-III, DSM-IV and ICD-10.

Diagnostic concordance of DSM-III, DSM-IV and ICD-10 was tested in a heterogeneous unrestricted sample of 370 clinical cases drawn from a regional consortium. Agreement for abuse/harmful use, dependence, and the collapsed category of 'any diagnosis' was studied across eight drug classes. A probabilistic approach to the cross-classifications based on configural frequency analysis was applied, permitting the computation of four indices of agreement. In contrast to earlier studies, ICD-10 appeared to be the most inclusive system, and often diagnosed cases that were undiagnosed by both DSMs. Generally satisfactory coherence between the ICD-10 harmful use category and the DSM category of abuse was found, but this agreement was often due to a preponderance of negative or undiagnosed cases; disagreement was common on which cases in particular warrant a mild diagnosis. In general, the greatest diagnostic concordance was observed for sedative/hypnotics, opiates and alcohol, the poorest for amphetamines, cocaine and PCP. The analytic approach produced an array of cross-system relationships that are more complex and conditional than those previously reported, and scientists and clinicians are cautioned to study particular drugs, diagnostic levels and measures of concordance before applying cross-system results to their own data or design needs.

Adult↗
PubMed2001

Modeling the extrafocal radiation and monitor chamber backscatter for photon beam dose calculation.

A simple analytical approach has been developed to model extrafocal radiation and monitor chamber backscatter for clinical photon beams. Model parameters for both the extrafocal source and monitor chamber backscatter are determined simultaneously using conventional measured data, i.e., in-air output factors for square and rectangular fields defined by the photon jaws. The model has been applied to 6 MV and 15 MV photon beams produced by a Varian Clinac 2300C/D accelerator. Contributions to the in-air output factor from the extrafocal radiation and monitor chamber backscatter, as predicted by the model, are in good agreement with the measurements. The model can be used to calculate the in-air output factors analytically, with an accuracy of 0.2% for symmetric or asymmetric rectangular fields defined by jaws when the calculation point is at the isocenter and 0.5% when the calculation point is at an extended SSD. For MLC-defined fields, with the jaws at the recommended positions, calculated in-air output factors agree with the measured data to within 0.3% at the isocenter and 0.7% at off-axis positions. The model has been incorporated into a Monte Carlo dose algorithm to calculate the absolute dose distributions in patients or phantoms. For three MLC-defined irregular fields (triangle shape, C-shape, and L-shape), the calculations agree with the measurements to about 1% even for points at off-axis positions. The model will be particularly useful for IMRT dose calculations because it accurately predicts beam output and penumbra dose.

Biophysical Phenomena↗
PubMed2004

Study design considerations in clinical outcome research of lung cancer using microarray analysis.

BACKGROUND: Prognosis following a diagnosis of primary lung cancer is very poor and varies significantly even after adjusting for known predictors. Inherent and acquired gene alterations could cause failure in lung cancer treatment and patient survival. To search for potential molecular markers with significant and independent predictive value in lung cancer survival, we applied oligo-nucleotide microarray analysis, along with patients' phenotypic profile, in a case-control study. The focus of this report is on the methodology used in the identification of potential genes as prognostic factors. METHODS: Selected from 304 patients at Mayo Clinic, 18 stage I squamous cell lung cancer patients who died within 2 years (high-aggressive) or lived beyond 5 years (low-aggressive) were included in this study. Both a one-to-one matched design (paired) and a two-group design (grouped) were utilized. Matching variables were age, gender, tumor size and grade, smoking status, and treatment. Two-GeneChip-array sets from Affymetrix (HG-U133) were used. We applied multiple analytic approaches including Dchip (Harvard University), SAM (Stanford University), ArrayTools (US National Cancer Institute), and MAS5 (Affymetrix); and integrated multiple results to generate the final candidate genes for further investigation. We evaluated the consistency across the methods and the effects of matched versus grouped design on the results. RESULTS: Using the same pre-processed data under the same criteria for type I error and fold-change in expression intensity, results are 94-100% concordant in the list of significant genes by Dchip and by ArrayTools, and 53% concordant between the paired and the grouped analysis. If using differently pre-processed data, the concordance rate is under 6% even by the same analytic tool. Combining results from all analyses, we found 23 potentially important genes that may distinguish the high- versus low-aggressive squamous cell tumors of the lung. CONCLUSION: Given the generally low consistency of results across analytic algorithms and study design, poor agreement is expected from different investigators reporting candidate genes for the same endpoint. A well-designed study with a carefully planned analytic strategy is critical. We are in the process of validating the 23 preliminary candidate genes found from this study among independent yet comparable cases.

Adult↗
PubMed1997

Nonlinear Dynamics of Lipid Films under Electric Forces

We study the dynamics and rupture of lipid films perturbed in the symmetric mode squeezing through an electrohydrodynamical approach. The lipid phase and the two surrounding aqueous phases are considered as incompressible Newtonian viscous fluids submitted to van der Waals, steric, and electric body forces. A nonlinear evolution equation for the film thickness, at the long-wavelength limit, is obtained for two symmetric cases: a film with equally charged surfaces with no potential drop and a neutral film submitted to an external electric field. At the long-wavelength limit, the electric term only influences the film evolution when the electric field inside the film is nonvanishing. We solve numerically, as an initial value problem with periodic boundary conditions, the nonlinear evolution equation. The rupture time is obtained and compared with analytical estimates. Sufficiently strong steric forces prevent the film from narrowing beyond a minimum thickness leading the film to a steady state different from the planar one consistently with the nonlinear analytical approach. The presence of a transmembrane electric potential destabilizes the perturbed film as predicted by the linear and nonlinear approaches; however, as expected, destabilization is not relevant at physiological values of the potential drop.

Journal Article↗