SEARCH · PubMed Health

Results for “Generation mean analysis”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 289 records · Page 16Linked to original sources

PubMed2005

Serum concentration of selenium in healthy individuals living in Tehran.

OBJECTIVE: To investigate whether daily diet provides adequate selenium intake in healthy men and women living in Tehran, Iran. METHOD: Serum level of selenium was determined in 184 healthy individuals of both genders. The samples were divided into two age groups, adults and children, for analysis. The serum level of selenium was determined using hydride generation and flame atomic absorption spectroscopy. RESULTS: The mean and standard deviation of serum selenium levels in children (1-16 years) was 84.3 +/- 11 microg/l and there was no significant difference between genders in this group. In adults (older than 16 years) the mean serum selenium level was 100.6 +/- 13 SD microg/l; among women the mean was 93.9 +/- 14 SD microg/l and among men it was 102.2 +/- 12 SD microg/l. The mean selenium level in men was higher than in women and data analysis showed a significant difference between them (p < 0.005). There was also a positive correlation between higher selenium serum concentration and age in men (P < 0.001). Daily intake of selenium in men and women was calculated to be 67 microg and 62.1 microg respectively. CONCLUSION: Our results show that the serum concentration of selenium in an Iranian population is similar to other nationalities in the Middle East, particularly Saudi Arabia.

Adolescent↗

PubMed2001

Recoupled polarization-transfer methods for solid-state (1)H--(13)C heteronuclear correlation in the limit of fast MAS.

An in-depth account of the effects of homonuclear couplings and multiple heteronuclear couplings is given for a recently published technique for (1)H--(13)C dipolar correlation in solids under very fast MAS, where the heteronuclear dipolar coupling is recoupled by means of REDOR pi-pulse trains. The method bears similarities to well-known solution-state NMR techniques, which form the framework of a heteronuclear multiple-quantum experiment. The so-called recoupled polarization-transfer (REPT) technique is versatile in that rotor-synchronized (1)H--(13)C shift correlation spectra can be recorded. In addition, weak heteronuclear dipolar coupling constants can be extracted by means of spinning sideband analysis in the indirect dimension of the experiment. These sidebands are generated by rotor encoding of the reconversion Hamiltonian. We present generalized variants of the initially described heteronuclear multiple-quantum correlation (HMQC) experiment, which are better suited for certain applications. Using these techniques, measurements on model compounds with (13)C in natural abundance, as well as simulations, confirm the very weak effect of (1)H--(1)H homonuclear couplings on the spectra recorded with spinning frequencies of 25--30 kHz. The effect of remote heteronuclear couplings on the spinning-sideband patterns of CH(n) groups is discussed, and (13)C spectral editing of rigid organic solids is shown to be practicable with these techniques.

Journal Article↗

PubMedDate not supplied

Dynamic heterogeneity: experimental metastasis studies with RIF-1 fibrosarcoma.

We have examined the metastatic behaviour of cells from a series of clones of RIF-1 fibrosarcoma, a recently derived murine tumour. The clones were grown to different sizes (small: 10(5)-10(6) cells and large approximately 2 x 10(7) cells) and their metastatic potential was quantified using an experimental metastasis assay. There was significant variability between the metastatic potential of clones derived from the same population. Furthermore large clones had higher metastatic efficiency (metastases/cell injected) than the small clones derived from the same population. The results from these experiments indicate that metastatic variants are generated during the growth of the clones. The mean effective rate of generation of metastatic variants was estimated using Luria-Delbruck fluctuation analysis to be 1.7 x 10(-5)/cell/generation. The data described are consistent with a dynamic heterogeneity model of metastasis, in which the variant phenotypes are postulated to arise in growing tumour cell populations at a high rate but need not be stable in order to produce metastases. The results thus indicate that the model is applicable to a recently derived tumour as well as the extensively transplanted KHT sarcoma, B16 melanoma and OTF9 embryonal cell carcinoma.

Animals↗

PubMed1982

Ultrasonic measurement of the femur length as an index of fetal gestational age.

Fetal femur length was measured with a linear-array, real-time ultrasound scanner in 145 uncomplicated gravid patients from 16 to 42 weeks' gestation. The data were analyzed by means of the method of least-squares linear regression. The results of this analysis generated the following equation: Y = -0.6809 + 0.2127 X (Y = femur length; X = gestational age.) With the use of these data, the error in estimation of gestational age given femur length in the interval 25 to 35 weeks' gestation is less than 5 days. Outside these intervals, there is less precision in this measurement, with a range from 8 days at 15 weeks to 6 days at 40 weeks. Furthermore, the correlation coefficient of gestational age versus fetal femur length is statistically greater than that of the gestational age versus fetal biparietal diameter. These results suggest that the measurement of the fetal femur length is a more precise index of gestational age than is the biparietal diameter. We propose that the ultrasonic measurement of the fetal femur length is a sensitive and precise variable for estimation of fetal growth and development.

Female↗

PubMed2000

Analysis of large-scale gene expression data.

The advent of cDNA and oligonucleotide microarray technologies has led to a paradigm shift in biological investigation, such that the bottleneck in research is shifting from data generation to data analysis. Hierarchical clustering, divisive clustering, self-organizing maps and k-means clustering have all been recently used to make sense of this mass of data.

Algorithms↗

PubMed1998

Automatic segmentation of magnetic resonance images of the trans-femoral residual limb.

An automatic algorithm for the extraction of the skin and bone boundaries from axial magnetic resonance images of the residual limb of trans-femoral amputees is presented. The method makes use of K-means clustering and mathematical morphology. Statistical analysis of the results indicates that the computer-generated boundaries compare favourably to those drawn by human observers. The boundaries may be used in biomechanical modelling of the interaction between the residual limb and the prosthetic socket. The limb/socket interface determines the quality of prosthetic fit, therefore knowledge of this interface is important for the improvement of socket design in order to achieve patient comfort and mobility.

Adipose Tissue↗

PubMed1995

Telomere length and replicative aging in human vascular tissues.

Because repeated injury of the endothelium and subsequent turnover of intimal and medial cells have been implicated in atherosclerosis, we examined telomere length, a marker of somatic cell turnover, in cells from these tissues. Telomere lengths were assessed by Southern analysis of terminal restriction fragments (TRFs) generated by HinfI/Rsa I digestion of human genomic DNA. Mean TRF length decreased as a function of population doublings in human endothelial cell cultures from umbilical veins, iliac arteries, and iliac veins. When endothelial cells were examined for mean TRF length as a function of donor age, there was a significantly greater rate of decrease for cells from iliac arteries than from iliac veins (102 bp/yr vs. 47 bp/yr, respectively, P < 0.05), consistent with higher hemodynamic stress and increased cell turnover in arteries. Moreover, the rate of telomere loss as a function of donor age was greater in the intimal DNA of iliac arteries compared to that of the internal thoracic arteries (147 bp/yr vs. 87 bp/yr, respectively, P < 0.05), a region of the arterial tree subject to less hemodynamic stress. This indicates that the effect is not tissue specific. DNA from the medial tissue of the iliac and internal thoracic arteries showed no significant difference in the rates of decrease, suggesting that chronic stress leading to cellular senescence is more pronounced in the intima than in the media. These observations extend the use of telomere size as a marker for the replicative history of cells and are consistent with a role for focal replicative senescence in cardiovascular diseases.

Adolescent↗

PubMed1995

Vertical transmission of Citrobacter diversus documented by DNA fingerprinting.

OBJECTIVE: To confirm the vertical transmission of Citrobacter diversus from a mother to her infant and to evaluate the epidemiologic usefulness of a new automated procedure for analysis of polymerase chain reaction (PCR)-generated DNA fingerprints. DESIGN: Repetitive element-based PCR (rep-PCR) analysis of C diversus isolates from the blood and amniotic fluid of a mother and the blood of her infant was performed. Unrelated C diversus isolates also were characterized and compared with the isolates from mother and infant. DNA fingerprints were generated by gel electrophoresis of PCR products derived from either unlabeled standard repetitive sequence-based oligonucleotide primers or fluorescent primers. The standard rep-PCR fingerprints were analyzed by visual inspection. The fluorescent primers were used in fluorophore-enhanced rep-PCR (FERP), and the FERP DNA fingerprints were analyzed by an Applied BioSystems (ABI) Model 373A laser scanning unit equipped with Genescan 672 software (Applied Biosystems, Inc, Foster City, CA). SETTING AND PATIENTS: A mother and her newborn infant, both with invasive disease due to C diversus, in an urban tertiary-care hospital. RESULTS: The DNA fingerprints of the maternal blood, amniotic fluid, and infant blood isolates of C diversus were identical by both visual inspection of ethidium bromide-stained agarose gels and computer-aided analysis of FERP patterns. These strains appeared to differ from all but one control isolate, which had been collected 7 years earlier in the same city in which the infant was born. CONCLUSIONS: Vertical transmission of C diversus from mother to infant can occur in utero. Automated analysis of rep-PCR-generated DNA fingerprints derived using fluorescent primers is an objective means for comparing isolates of C diversus and in all likelihood would be useful for other species of bacteria that possess repetitive elements.

Adult↗

PubMed1995

Preferential correlations of a medullary neuron's activity to different sympathetic outflows as revealed by partial coherence analysis.

1. In vagotomized, paralyzed, decerebrate cats, simultaneous recordings were taken from one or more sympathetic nerves [cervical sympathetic (CS), inferior cardiac (IC), splanchnic (SP)] and from medullary neurons in vasomotor-related regions. Coherence analyses were used to ascertain the presence of sympathetic rhythms (2-6 Hz or "3-Hz rhythm," 7-13 Hz or "10-Hz rhythm") that were correlated between different signals. The occurrence of a significant peak at such a frequency in a unit-nerve coherence spectrum allowed the identification of a medullary neuron as sympathetic related. 2. A serendipitous example is given of a rostral ventrolateral medullary neuron that had significant unit-nerve 10-Hz coherence peaks for three sympathetic nerves (CS, IC, SP); but, as revealed by partial coherence analysis, the unit activity's correlation with one nerve's activity could be partially or completely dependent on its correlation with other nerve activities. Thus in this case the unit-CS and unit-IC coherences at 10 Hz were completely dependent on the SP rhythm, whereas the unit-SP coherence was not significantly affected by the CS and IC rhythms. This asymmetry suggests that the neuron was preferentially connected to SP-generating medullary circuits. 3. This example indicates the strength of partial coherence analysis as a means of studying differential connectivity between medullary sympathetic-related neurons and sympathetic output neuron populations.

Animals↗

PubMedDate not supplied

Information needs of adolescents with cancer.

Adolescents with cancer (AWC) have poorer treatment outcomes as well as higher incidence and mortality rates than do younger children, and they face additional challenges related to normal developmental issues of adolescence. Although research has shown that information on the cancer experience improves outcomes by decreasing uncertainty and increasing perceived support, little is known about the types of information AWC need and want. This study describes how AWC rate the importance of specific cancer-related information, analyzes gender and age group differences, and compares 2 different time-since-diagnosis groups of AWC. The sample consisted of adolescents with newly diagnosed cancer (n = 74) and those 1 to 3 years from diagnosis (n = 39). The Information Preferences of Adolescents (IPA) Scale was used to measure the adolescents' information needs. Both samples of AWC rated the need for information as high. There were no significant differences by age, but females had significantly higher total scores for both groups and for many item means in the newly diagnosed group. Qualitative analysis of the additional write-in items generated 4 themes: treatment/side effects, uncertainty, social issues, and personal/emotional issues.

Adolescent↗

PubMed2005

A social semiotic interpretation of suicidal behaviour in young people.

This article presents a study of nurses' and doctors' perceptions of young people who engage in suicidal behaviour. A contemporary view of grounded theory is used to guide the collection and analysis of qualitative data from nurses and doctors working with young people in an accident and emergency department, paediatric medicine and child and adolescent mental health services (adolescent inpatient unit). The analysis of 45 semi-structured interviews generated the category: Processes of communication and associated meanings: Another voice, Complex messages and Seeing and using the social environment. A social semiotic framework is used to explore the way in which nurses and doctors perceive young people who engage in suicidal behaviour. The article concludes by considering the implications for policy and practice.

Adolescent↗

PubMedDate not supplied

Development of a functional disability measurement tool to assess early arthritis: the Recent-Onset Arthritis Disability (ROAD) questionnaire.

OBJECTIVE: To develop a self-administered questionnaire, the ROAD (Recent-Onset Arthritis Disability), to probe physical disability in Italian patients with early arthritis (EA) of less than one year's duration. METHODS: The development of the ROAD follows a series of major steps: (1) identification of a specific patient population, (2) item pool development, (3) item reduction, (4) internal consistency, (5) pre-testing of the prototype instrument, and (6) a validation study which results in determination, reliability, validity and responsiveness. In this study we have verified the first five steps. Pre-defined areas of disability were culled from eight existing Italian version arthritis-specific questionnaires, and three generic global health measurement tools. Semi-structured interviews helped to derive a 76-item pool from an initial group of 122 items. This questionnaire was administered to 78 EA patients. RESULTS: For scale generation, a combination of frequency importance product (FIP = frequency x mean relevance score) and factor analysis was applied. The top 20 items based on the FIP were then subjected to further analysis. Each question was correlated with every other question. This allowed us to eliminate 8 questions that were therefore highly correlated and were measuring the same concept. The final instrument has 12 items, representing a combination of symptoms that are common, frequently recurring and of general importance to EA patients. Factor analysis provides a 3-factor health status model explaining 70.1% of the variance. The upper extremity function (5 items) is loaded on the first factor, which explains 45.4% of the total measured variance. The lower extremity function (4 items) formed the second factor (14.2% of the total variance). The third factor was determined by activities of daily living/work (3 items) and explain 10.5% of the total variance. The score of the different subscales can be presented graphically as a ROAD profile. CONCLUSION: Using a traditional development strategy, we have constructed a self-administered instrument for measuring physical functioning in patients with EA. The next stage includes reliability, validity and responsiveness testing of the 12-item questionnaire.

Activities of Daily Living↗

PubMed1985

Course and complications of endoscopic variceal sclerotherapy: a prospective study of 50 patients.

Fifty consecutive patients with bleeding esophageal varices were treated with endoscopic variceal sclerotherapy (EVS) using the free hand method and a flexible fiberoptic endoscope. During the study period, November 1981 through April 1984, 11 patients (22%) rebled after the initiations of EVS and six patients were lost to follow-up. Obliteration of esophageal varices was achieved in 14 patients and none of these patients rebled for a mean follow-up time of 305 days. Survival curves generated by Willcoxson life table analysis demonstrated 51% 1-year survival for all patients, 21% for Child's class C patients, and 100% for Child's A and B patients. The complications associated with EVS were ulcerations 78%, strictures 20%, fever 44%, and perforations 2%. This study indicates that EVS is a safe and effective treatment for acute variceal hemorrhage and obliteration of esophageal varices can be achieved. Once varices are obliterated rebleeding may not occur. Survival in Child's A and B patients may be improved with EVS but the survival in Child's C patients is unaffected.

Acute Disease↗

PubMed1979

[Response of pericruciate cortex neurons to stimulation of the medial geniculate body].

Electrical responses of 239 pericruciate neurons were studied in anaesthetized and curarized cats after stimulation of the medial geniculate body and medullary pyramids. The medial geniculate body stimulation evoked in the pericruciate neurons predominantly excitatory effects in the form of increase in the mean frequency of spike activity, generation of EPSPs and EPSPs-spike sequences. The latency analysis has shown that medial geniculate neurons have mono- and polysynaptic connections with pericruciate neurons not belonging to the pyramidal tract units.

Animals↗

PubMed1979

Relationships between hemodynamic profiles and topography of acute myocardial infarction.

Initial hemodynamics were studied in 101 patients with acute myocardial infarction complicated by shock or left heart failure. 59 had anterior myocardial infarction (AMI); 42 had inferior myocardial infarction (IMI). Data were processed by univariate analysis and correspondence analysis. AMIs and IMIs were significantly different on conduction disturbances, heart rate, left ventricular filling pressure, mean pulmonary artery pressure and right ventricular function indices. Both patients and parameters were projected on the most meaningful factorial plane generated by correspondence analysis. This two-dimensional graphical representation showed that all the information was roughly distributed along the 2 orthogonal axes defining this plane. Survivors and nonsurvivors were fairly well separated along the first factorial axis (prognostic axis) which was highly correlated with both outcome and left ventricular function parameters. AMIs and IMIs were grossly separated along the second factorial axis (topographical axis) which was rather well correlated with location and right ventricular function parameters. These studies suggest that AMI and IMI hemodynamic profiles are modulated by the presence or absence of right ventricular dysfunction. Moreover right ventricular dysfunction may be held responsible of some lack of information about left ventricular function status.

Acute Disease↗

PubMed2001

The cost utility analysis of riluzole for the treatment of amyotrophic lateral sclerosis in the UK.

This study reports the results of a long-term economic evaluation of riluzole in the treatment of amyotrophic lateral sclerosis (ALS) versus best supportive care in the United Kingdom. The aim was to assess the cost implications of the life extension offered by riluzole through cost utility analysis based on patient assessed utilities of different health states.A Markov model was used to assess the cost-effectiveness of Rilutek with best supportive care. Transition possibilities and the distribution of patients by health states were taken from a cohort of 954 patients drawn from a large randomised, double blind, placebo-controlled, multicentre trial between 1992 and 1994 in the first 18 months and used to extrapolate the model to assess the long-term prolongation of life. Four distinct health states were used corresponding to mild, moderate, severe and terminal states. Costs associated with Rilutek included the acquisition cost and bi-monthly monitoring for raised ALT levels. Patient assessed utilities were collected by use of the standard gamble technique. 77 patients were entered into the study from two centres (King's, London and Preston) in the UK. Mean utilities for each of the health states was generated and, given that the data were skewed, a sensitivity analysis was undertaken with the median utility values. The implications of life extension offered by riluzole versus best supportive care were assessed both in terms of life extension projected and quality adjusted survival using patient based utilities. Using the Markov model and the transitional probabilities the base case cost per life year gained was estimated at pound sterlings 14,370 and applying Standard Gamble utility scores, the base case cost per QALY was assessed as pound sterlings 20,904. The effect of discounting costs and benefits altered the cost effectiveness analysis to pound sterlings 17,760 per life year gained while a sensitivity analysis around median or mean scores for the utility weight resulted in a range of pound sterlings 19,020 to pound sterlings 25,794 per QALY gained.

Amyotrophic Lateral Sclerosis↗

PubMed2006

Reduced pretreatment ipsilateral middle cerebral artery cerebral blood flow is predictive of symptomatic hemorrhage post-intra-arterial thrombolysis in patients with middle cerebral artery occlusion.

BACKGROUND AND PURPOSE: Intracerebral hemorrhage (ICH) can be a devastating complication associated with thrombolytic therapy for acute ischemic stroke. We hypothesized that patients with lower prethrombolysis cerebral blood flow (CBF) were at a higher risk of symptomatic ICH (sICH). METHODS: Twenty-three patients who underwent quantitative CBF assessment with Xenon CT studies for acute stroke before intra-arterial (IA) thrombolysis for a middle cerebral artery (MCA) or internal carotid artery terminus occlusion within 6 hours of symptom onset were studied. Univariate and multivariate analysis were carried out to determine predictors of sICH post-IA thrombolysis. Receiver operating characteristic curves were generated to determine the association between mean ipsilateral CBF and the occurrence of sICH. RESULTS: The mean age of our cohort was 68+/-12 years and a mean National Institutes of Health Stroke Scale (NIHSS) score of 18+/-3. In univariate analysis, patients with higher percent of core infarct, hyperglycemia, and reduced mean ipsilateral CBF were at risk of sICH. In multivariate analysis only mean ipsilateral CBF was associated with higher rates of sICH (odds ratio 1.58; 95% CI, 1.01 to 2.51; P<0.04). The area under the receiver operating characteristic curve was 0.87 (95% CI, 0.76 to 0.97; P<0.005). CONCLUSIONS: Patients with lower pre-IA thrombolysis mean ipsilateral MCA CBF are at significantly higher risk for sICH in the setting of a MCA or carotid terminus occlusion. The threshold identified in this study may be useful for selection of patients with acute MCA occlusions for acute stroke thrombolysis.

Aged↗

PubMed2000

Anticipation phenomenon in familial adenomatous polyposis:an analysis of its origin.

AIM:To analyze the origin of the anticipation phenomenon, which means earlier death in successive generation in familial adenomatous polyposis.METHODS:The study subjects were 2161 patients with familial adenomatous polyposis and their 7465 first degree relatives who were members of 750 families registered at our Polyposis Registry. The ages at death and cumulative mortality rates in theparent, the proband, and the child generations were compared for both all subjects and the patients alone.RESULTS:In the patients over 5 years of age, the mean age at death was 50.9 years for the parent, 42.3 years for the proband, and 33.3 years for the child generations, respectively a(c)(P < 0.001). The deceased rates in the three generations were 90.7%, 51.3% and 23.1% of the patients, respectively, and this difference was the main cause of the anticipation measured by parent-child paring method. The cumulative mortality rates for all subjects failed to show anticipation, however the cumulative mortality rates for the patients showed the anticipation. The anticipation phenomenon was shown by any parent-child pairing methods for the deceased patients. Other important causes of the anticipation were different proportion of causes of death between generations a(c)(P <0.001), and a low proportion of detected or deceased patients (P < 0.001) in the child generation.CONCLUSION:Anticipation in familial adenomatous polyposis may be caused by parent child paring methods as well as several intergenerational biases.

Journal Article↗