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PubMed1988

Assessment of aortoiliac stenosis by femoral artery pressure measurement and Doppler waveform analysis.

Two-hundred and four aortoiliac segments of 102 patients with arterial disease of the legs were examined for evidence of aortoiliac stenosis by Doppler analysis of the common femoral artery, angiography and direct femoral artery pressure (FAP) measurements at rest and after induction of hyperaemia with papaverine. From the continuous wave and multigate Pulsed Doppler waveforms registered at rest and during postocclusion hyperaemia, the following instantaneous maximum frequency envelope parameters were calculated: maximum forward frequency, maximum reverse frequency, systolic upslope time (UST) and Pulsatility Index. The overall correlation of these parameters with the apriori classifications of the aortoiliac segments, based on FAP measurements and angiography, were poor. By multiple regression analysis the UST appeared to be the Doppler waveform parameter with the best predictive value for significant aortoiliac stenosis.

Aorta, Thoracic↗
PubMed2004

[Multifactor analysis in prediction of outcome for ischemic stroke with combined cardiac symptomatology].

Basing on the results of multiple classifications of 70 clinical, paraclinical and anamnestic signs of ischemic stroke with combined cardiac symptomatology, the models predicting clinical outcome in acute period of the disease and an original scale of numerical score have been worked out. It is mathematically proved that the severity of ischemic stroke with combined cardiac symptomatology, scoring 75 and above, inevitably results in progression of fatal outcome. A group of unfavorable clinical predictors was singled out. The periods with high rate of fatal outcome within exacerbation of ischemic stroke and pathogenic types of stroke were studied. It is first-ever shown that a role of cardiac and neurological symptoms in predicting fatal outcome depends on ischemic stroke severity. A relation between the probable fatal outcome and dynamics of severity of stroke with combined cardiac symptomatology within the first 3 days of the disease was also revealed for the first time.

Adult↗
PubMed1998

Classification and properties of 64 multiplexed microsphere sets.

We describe a practical method for the analysis of multiple analytes in a single sample. The vehicle for each separate measurement consists of a set of microspheres identifiable by characteristic fluorophores embedded in the particles. The use of robust, bench-top flow cytometers (flow microfluorimeters) for the analysis of the multiple sets of microspheres is facilitated by hardware and software, which acquire the data from the cytometer, classify the microspheres according to sets, and collate measurement information from each microsphere set in real time. This measurement system can analyze up to 64 analytes in a single sample. The advantages of multiplexed assays using flow cytometry include robust measurements, because each microsphere set is measured repeatedly. The advantage of the assay's is consistent with simultaneous measurement of many parameters as well as the speed with which the flow microfluorimeter (cytometer) makes measurements (many hundreds per second). Here, we describe the properties of the microspheres, the calibration of the cytometer, and the influence of the properties of the microspheres on the sensitivity of measurements.

Calibration↗
PubMed1996

A computer aided system for systematic production and revision of sequence patterns.

We used two complementary fields, object-oriented databases and machine learning, to produce and revise a set of protein sequence patterns. In a first stage, we show that object-oriented query languages are well suited for the production of patterns as well as for the interpretation of the biological function of new (uncharacterized) sequences. In a second stage, a classification is built from the set of sequences according to the pattern matches. This classification may be criticized by a specific analysis method, which yields back to revise sequences and patterns. In our application, we have used concept lattices as a classification method and sequence multiple alignment for criticism.

Algorithms↗
PubMed1987

Prognostic significance of plasma cell morphology in multiple myeloma.

The effect of bone marrow plasma cell morphology at diagnosis on survival time was evaluated in 139 patients with multiple myeloma. According to the morphological classification scheme the patients were categorized as mature (30 patients), immature (76 patients) or plasmablastic (33 patients). The plasmablastic group had an estimated median survival (Kaplan-Meier method) of 10.9 months, compared with 32.2 months for immature and 60 months for mature types (P = 0.0000). The prognostic value of a morphologic classification in multiple myeloma was further demonstrated by means of a multivariate linear regression analysis of survival data. Expected survival was calculated using clinical features and morphologic subtypes. The estimated survival time for plasmablastic myeloma was shorter by 51.4 months and for immature myeloma patients by 35 months, compared with mature myeloma patients with similar clinical characteristics. Plasma cell morphology at diagnosis is an important predictor of survival duration in patients with multiple myeloma.

Bone Marrow↗
PubMed1999

The role of emission tomography in dementia.

Positron emission tomography (PET) and single photon emission tomography (SPET) offer the opportunity to improve a diagnosis of dementia by providing regional functional measurements, which can be used to substantiate the clinical judgement. Further progress in the differential diagnosis among degenerative dementias is expected from pathological confirmation in the follow-up of patients evaluated with neuroimaging methods. A prospective multi-center cohort study of patients with possible or probable Alzheimer's disease mostly with presenile onset, showed impairment of brain glucose metabolism in temporoparietal or frontal association areas, as measured with PET. This was associated significantly with dementia severity, clinical classification, presence of multiple cognitive deficits, and history of progression. In addition, prospective longitudinal analysis showed a significant association between initial metabolic impairment (metabolic ratio = 0.80) and subsequent clinical deterioration. In patients with mild cognitive deficits at entry, the risk of deterioration was up to 4.7-times higher if metabolism was severely impaired than with mild or absent metabolic impairment. In the future, it might be possible to use different tracers to measure neurotransmitter release or receptor function. It may also be possible to scan the patient while performing cognitive tasks to examine changes in functional brain activity during pharmacological treatments.

Alzheimer Disease↗
PubMed1994

Combined use of cerebral spinal fluid drainage and naloxone reduces the risk of paraplegia in thoracoabdominal aneurysm repair.

PURPOSE: This report summarizes our experience with the use of cerebral spinal fluid drainage (CSFD) and naloxone for prevention of postoperative neurologic deficit (paraplegia or paraparesis). METHODS: We reviewed 110 consecutive patients with 86 thoracoabdominal aneurysms and 24 thoracic aneurysms. The status of 47 patients (43%) was acute (rupture or dissection), and the status of 52 (47%) was Crawford type I or II. None of the patients had intercostal artery reimplantation. There were two patient groups for analysis of neurologic deficit risk. Group A (61 patients) received naloxone and CSFD, and group B (49 patients) did not. RESULTS: One deficit occurred in group A and 11 deficits occurred in group B (p = 0.001). By multiple logistic regression analysis, the variables acute status, Crawford type II, or group B classification were significant factors for deficit risk. Use of the same logistic regression analysis on the subgroup of 47 patients with acute aneurysms and 33 patients with Crawford type 2 aneurysms confirmed the protective effect of combined CSFD and naloxone (group A) and that clinical presentation and extent of aorta replaced are the primary risk factors for development of deficit. To test this conclusion we developed a highly predictive model (correlation coefficient 0.997 with 16 series of thoracoabdominal aneurysms) for neurologic deficit. We applied our data to this model. Group B had the predicted number of deficits, and group A had substantially fewer deficits than predicted. CONCLUSIONS: We conclude that the combined use of CSFD and naloxone offers significant protection from neurologic deficits in patients undergoing thoracoabdominal and thoracic aortic replacement.

Adolescent↗
PubMedDate not supplied

Predicting bond lengths in planar benzenoid polycyclic aromatic hydrocarbons: a chemometric approach.

Two hundred and twenty-three aromatic carbon-carbon bond lengths in high precision crystal structures containing 22 planar condensed benzenoid polycyclic aromatic hydrocarbons (PB-PAHs) were related to the Pauling pi-bond order, its analogue corrected to crystal packing effects, the number of hexagonal rings around the bond, and the numbers of carbons atoms around the bond at topological distance one and two. Principal Component Analysis (PCA) showed that the bond lengths in PB-PAHs are at least two-dimensional phenomenon, with well pronounced classification into 12 types of bonds, as confirmed with Hierachical Cluster Analysis (HCA). Consequently, Multiple Linear Regression (MLR) and Partial Least Squares (PLS) models were superior to univariate models, reducing the degeneration of the data set and improving the estimation of Julg's structural aromaticity index. The approximate regression models based on topological descriptors only were built for fast and easy prediction of bond lengths and bond orders in PB-PAHs.

Journal Article↗
PubMed2002

Correlation between mandibular central incisor proclination and gingival recession during fixed appliance therapy.

The purpose of this study was to determine whether proclination of mandibular central incisors during fixed appliance therapy results in gingival recession. Complete records of 67 patients (39 female and 28 male patients; mean age, 16.4 years; age range, 10-45 years) were used in this retrospective case-control study. Using pretreatment and posttreatment lateral cephalograms, the change in mandibular central incisor inclination was measured to divide the patients into an experimental group (proclination) and a control group (no proclination). Changes in clinical crown length were determined from pretreatment and posttreatment study models, and changes in gingival recession were determined from intraoral slides. Eight of the 67 patients exhibited a measurable increase in gingival recession of at least 0.5 mm, and 27 patients had an increase in clinical crown length of at least 0.5 mm. Statistical analyses showed no correlation between mandibular central incisor proclination and gingival recession or clinical crown length. A t-test analysis showed no statistically significant difference in gingival recession or change in clinical crown length between patients whose mandibular central incisors were proclined and those whose incisors were not proclined. Multiple regression analysis demonstrated that age, sex, race, treatment duration, extraction, treatment type, Angle classification, and proclination were not related to gingival recession or change in clinical crown length of mandibular central incisors. We conclude that the degree of proclination of mandibular central incisors during fixed appliance therapy was not correlated to gingival recession in this sample.

Adolescent↗
PubMed1987

Prediction of vocal severity within and across voice types.

Fifty-one subjects representing diverse laryngeal etiologies recorded /a/ and /i/ to provide a study sample of 102 vowel sounds. Listeners categorized each vowel on the basis of four voice types (normal, breathy, hoarse, unclassified) and evaluated the degree of vocal abnormality on a 7-point scale. In addition to spectrographic noise (SN) classification, several acoustic measures based on period variability were entered into a multiple regression analysis for the prediction of vocal severity across and within voice types. In general, spectrographic noise and curvilinear derivatives of the period standard deviation (PSD) provided the best predictions of disorder severity. Different variables were the major predictors for different voice types. Several variables used in previous studies were inefficient as predictors of severity.

Adolescent↗
PubMed2006

Macrophage infiltration detected at MR imaging in rat kidney allografts: early marker of chronic rejection?

PURPOSE: To evaluate detection of iron-loaded macrophages at magnetic resonance (MR) imaging as a noninvasive means to monitor early signs of chronic allograft rejection in the life-supporting Fisher-to-Lewis rat kidney transplantation model. MATERIALS AND METHODS: Experiments followed the Swiss federal regulations of animal protection. Male Fisher (n = 37) and Lewis (n = 77) rats were used. After removal of a native recipient kidney and transplantation of a donor kidney, the recipient rat's contralateral kidney was removed. Allografts and control syngeneic grafts comprised, respectively, kidneys from Fisher and Lewis donors transplanted into Lewis rats. Recipients were imaged by using a gradient-echo MR sequence 24 hours after intravenous administration of superparamagnetic iron oxide (SPIO) particles. Biochemical analyses of blood and urine, as well as assessments of Banff scores (reference standard for histologic classification of graft rejection), were performed. Statistical tests used were analysis of variance for multiple comparisons with Bonferroni tests, Mann-Whitney tests, and Pearson correlations with Bonferroni corrections. RESULTS: A SPIO dose-dependent decrease in cortical MR signal intensity occurred in allografts between 8 and 16 weeks after transplantation. A strong significant negative correlation (P = .005 for 0.3 mL/kg SPIO dose, P = .003 for 1.0 mL/kg SPIO dose) was found between MR signal intensity and Banff scores, which deteriorated over the experimental period. Proteinuria occurred at 16 weeks. Blood and urine creatinine levels remained unchanged up to week 28. CONCLUSION: This MR imaging method is more robust than the usually adopted creatinine clearance method for the detection of early signs of allograft chronic rejection in the Fisher-to-Lewis rat kidney transplantation model.

Animals↗
PubMed1991

[Clinical studies on prognostic factors in predicting pregnancy].

During the 5-year period from January 1984 to December 1988, 1,025 men were investigated for infertility. The patients were classified according to WHO laboratory manual. Using life-table analysis, WHO's classification of semen analysis was a useful discriminant for infertility prognosis. The Cox's multiple regression model was employed to investigate the relationship between various semen characteristics and future fertility. The duration of infertility, sperm concentration, sperm progressive motility, the presence of female factor were independent and statistically significant factors which influence the cumulative probability of conception.

Adult↗
PubMedDate not supplied

Transition to college: A classification and regression tree (CART) analysis of natural reduction of binge drinking.

Approximately one in five teens that drank heavily in high school reduces or discontinues consumption while in college. Multiple paths might lead to the common outcome of natural reduction in heavy drinking. Statistical modeling of this complex process of natural reduction is a challenge with standard linear statistics. The purpose of this paper is to use a new statistical procedure, Classification and Regression Tree (CART), to model the equifinality of reduction in drinking by college students who drank heavily as adolescents. An appealing aspect of CART is that the resulting tree model that can easily be interpreted and applied by those who work with adolescents during the important transition from high school to college. Of 201 college students who first binged on alcohol while in high school, 71 (35.3%) denied heavy or binge drinking within the previous three months (Natural Reducers). The final model accurately classified 84.6% of the students as either continued heavy drinkers or natural reducers. Sensitivity was modest (accurate identification of 67.6% of the reducers); however, specificity was strong (correct classification of 93.8% of the continued heavy drinkers). The model revealed four pathways to natural reduction in drinking. Predominant in each path was the influence of social factors that maintain continued drinking (e.g., social facilitation outcome expectancies, perception of friends' drinking) or facilitate natural reduction (e.g., regular church attendance). The results support the application of CART to model health behaviors across the transition from adolescence to young adulthood.

Adolescent↗
PubMed2006

Metabolic profiling of glucuronides in human urine by LC-MS/MS and partial least-squares discriminant analysis for classification and prediction of gender.

Mass spectrometry (MS) is increasingly being used for metabolic profiling, but detection modes such as constant neutral loss or multiple reaction monitoring have not often been reported. These modes allow focusing on structurally related compounds, which could be advantageous for situations in which the trait under investigation is associated with a particular class of metabolites. In this study, we analyzed endogenous glucuronides excreted in human urine by monitoring characteristic transitions of putative steroid glucuronides by LC-MS/MS for discrimination of females from males. Two methods for data extraction were used: (i) a manual procedure based on visual inspection of the chromatograms and selection of 23 peaks and (ii) a software-supported method (MarkerView) set to extract 100 peaks. Data from 10 female and 10 male students were analyzed by principal component analysis (PCA) and partial least-squares discriminant analysis (PLS-DA) using software SIMCA. With PCA, only the manual peak selection resulted in clustering males and females. With PLS-DA, the manual method provided full separation on the basis of one single discriminant; the software-supported approach required a two-component model for complete separation. Loading plots were analyzed for their ability to reveal peaks with high discriminating power, that is, potential biomarkers. The PLS-DA models were validated with urine samples collected from five new females and five new males. Gender was correctly assigned for all. Our results indicate that inclusion of biological criteria for variable selection coupled to class-specific MS analysis and data extraction by appropriate software may constitute a valuable addition to the methods available for metabolomics.

Adult↗
PubMed2006

Analysis of EEG-fMRI data in focal epilepsy based on automated spike classification and Signal Space Projection.

Simultaneous acquisition of EEG and fMRI data enables the investigation of the hemodynamic correlates of interictal epileptiform discharges (IEDs) during the resting state in patients with epilepsy. This paper addresses two issues: (1) the semi-automation of IED classification in statistical modelling for fMRI analysis and (2) the improvement of IED detection to increase experimental fMRI efficiency. For patients with multiple IED generators, sensitivity to IED-correlated BOLD signal changes can be improved when the fMRI analysis model distinguishes between IEDs of differing morphology and field. In an attempt to reduce the subjectivity of visual IED classification, we implemented a semi-automated system, based on the spatio-temporal clustering of EEG events. We illustrate the technique's usefulness using EEG-fMRI data from a subject with focal epilepsy in whom 202 IEDs were visually identified and then clustered semi-automatically into four clusters. Each cluster of IEDs was modelled separately for the purpose of fMRI analysis. This revealed IED-correlated BOLD activations in distinct regions corresponding to three different IED categories. In a second step, Signal Space Projection (SSP) was used to project the scalp EEG onto the dipoles corresponding to each IED cluster. This resulted in 123 previously unrecognised IEDs, the inclusion of which, in the General Linear Model (GLM), increased the experimental efficiency as reflected by significant BOLD activations. We have also shown that the detection of extra IEDs is robust in the face of fluctuations in the set of visually detected IEDs. We conclude that automated IED classification can result in more objective fMRI models of IEDs and significantly increased sensitivity.

Cerebral Cortex↗
PubMedDate not supplied

Perinatal mortality in Jamaica 1986-1987.

A large population-based study of all stillbirths and neonatal deaths occurring on the island of Jamaica during a 12 month period is described. During this time, 2069 perinatal deaths were identified in an estimated total of 54,400 infants born giving a perinatal death rate of 38.0 per 1000 births. The death rate was 5 times higher among twins than singletons. An attempt was made to obtain detailed postmortem examination of as many cases as possible. In the event, 51% of the infants who died perinatally had such postmortem examination. Postmortem rate was affected by sex, multiplicity of the infant, time of death, month of death and area of delivery. Deaths were classified using the Wigglesworth scheme. The distribution of categories was similar in the months when the postmortem rate was 70% to the rest of the time period when the post-mortem rate was only 40%. The Wigglesworth classification of deaths identified those associated with intrapartum asphyxia as the most important group, accounting for over 40% of deaths overall and 59% of deaths in infants of more than 2500 g birthweight. Antepartum fetal deaths were the second largest group, comprising 20% of deaths. Sixty percent of the infants in this group weighed less than 2500 g at birth. Major malformations were responsible for few perinatal deaths in Jamaica. This simple classification is important as it focuses attention on details of labour and delivery that may require change and is useful in planning future delivery of obstetric and neonatal care.

Asphyxia Neonatorum↗
PubMed2005

Associating phenotypes with molecular events: recent statistical advances and challenges underpinning microarray experiments.

Progress in mapping the genome and developments in array technologies have provided large amounts of information for delineating the roles of genes involved in complex diseases and quantitative traits. Since complex phenotypes are determined by a network of interrelated biological traits typically involving multiple inter-correlated genetic and environmental factors that interact in a hierarchical fashion, microarrays hold tremendous latent information. The analysis of microarray data is, however, still a bottleneck. In this paper, we review the recent advances in statistical analyses for associating phenotypes with molecular events underpinning microarray experiments. Classical statistical procedures to analyze phenotypes in genetics are reviewed first, followed by descriptions of the statistical procedures for linking molecular events to measured gene expression phenotypes (microarray-based gene expression) and observed phenotypes such as diseases status. These statistical procedures include (1) prior analysis, such as data quality controls, and normalization analyses for minimizing the effects of experimental artifacts and random noise; (2) gene selections and differentiation procedures based on inferential statistics for the class comparisons; (3) dynamic temporal patterns analysis through exploratory statistics such as unsupervised clustering and supervised classification and predictions; (4) assessing the reliability of microarray studies using real-time PCR and the reproducibility issues from many studies and multiple platforms. In addition, the post analysis to associate the discovered patterns of gene expression to pathway and functional analysis for selected genes are also considered in order to increase our understanding of interconnected gene processes.

Algorithms↗