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PubMed2006

[Complex tremor analysis for the differential diagnosis of essential tremor and Parkinson's disease].

OBJECTIVE: Tremor is the most common movement disorder which is most often either essential or caused by Parkinson's disease. The differentiation of these disorders at the initial stage may be difficult. Objective assessment of the efficacy of tremor medications is only possible by instrumental measurements. The aim of this study was to determine whether the computer assisted tremor analysis system CATSYS 2000 can help in the differentiation of parkinsonian from essential tremor. METHODS: The rhythmicity and maximal frequency of fast alternating hand and finger movements, simple reaction time and postural instability were recorded in healthy controls (n = 18), patients with Parkinson's disease (n = 39) and essential tremor (n = 37). Data were digitally converted and statistically analyzed. RESULTS: Tremor intensity, median frequency and frequency distribution showed characteristic differences in the three groups. Performance in fast alternating movements of hands and fingers were significantly worse in both tremor groups compared to the healthy controls. CONCLUSIONS: The data also indicated that quantitative measurements of tremor parameters must be performed on both sides, because the presence of significant side differences support the diagnosis of Parkinson's disease. The method presented can be used to objectively analyze tremor and performance in rhythmic movements. The results show that it helps to differentiate parkinsonian from essential tremor as well as to predict disease course and the effectiveness of therapy. Multivariate statistical analysis of tremor and movement performance also provides an opportunity to study the pathogenesis of human tremor.

Adult↗
PubMed1996

The effects of salinity change on the exercise performance of two Atlantic cod (Gadus morhua) populations inhabiting different environments

The objective of this study was to determine whether differences in exercise physiology between Atlantic cod (Gadus morhua) populations from different salinity environments could be changed by acclimating individuals of each population to the natural salinity of the comparison population. The exercise-associated blood chemistry of cod from the brackish Bras d'Or lakes, which had previously been shown to be quite different from that of 'open-ocean' cod, changed to resemble the blood chemistry of their oceanic relatives after only 2 months of acclimation to full-strength salinity. In contrast, the blood chemistry of cod from the Scotian Shelf of the Northwest Atlantic Ocean showed little change after 2 months of acclimation to brackish water. These results demonstrate that the degree of osmoconformity to changes in environmental salinity is a population-specific not a species-specific trait. The blood chemistry differences between populations and salinities did not translate into differences in exercise performance: i.e. critical swimming speeds were statistically uniform across all combinations of population and salinity, although performance was more varied in fish swimming in 'non-native' waters. Other 'whole-animal' physiological characteristics, such as metabolic rate and the aerobic cost of transport, were dependent upon both population origin and the environmental salinity. Vigorous swimming was more energetically expensive at full-strength salinity than at 20 salinity, yet estimates of standard (i.e. resting) metabolic rate were lower for full-strength salinity. Environmental salinity also influenced the relative appearance of lactate and metabolic acid in the extracellular fluid compartment, with full-strength salinity favouring the relative appearance of lactate in the blood. Multivariate statistical analyses of this data set showed that, in contrast to other fish species and studies, differences in blood oxygen transport appear to account for some of the swimming performance differences seen in Atlantic cod at 2 °C. The two experimental populations were cleanly separated by a principal components analysis, regardless of the salinity to which they were acclimated, confirming our earlier contention that these cod populations are physiologically distinct. A key feature of that distinctness is the greater phenotypic plasticity exhibited by the population from the more euryhaline, more eurythermal environment.

Journal Article↗
PubMed2005

How well do clinicians estimate third molar extraction difficulty?

PURPOSE: The goals of this study were to measure surgeons abilities to estimate third molar (M3) extraction difficulty and to identify variables associated with errors in estimates of difficulty. MATERIALS AND METHODS: To address our research purpose, we implemented a prospective cohort study and enrolled a sample of surgeons who remove M3s. Predictor variables were categorized as either surgeon or subject specific. The primary outcome variable was the error in estimating operative difficulty. Preoperative and postoperative estimates of difficulty were obtained using a 100-mm visual analogue scale. Error was defined as the difference between preoperative and postoperative estimates of extraction difficulty. Appropriate univariate, bivariate, and multivariate statistics were computed. RESULTS: The sample was composed of 15 surgeons who operated on 82 subjects having 250 M3s (53.2% mandibular) extracted. The mean level of surgical experience was 8.8 +/- 11.1 years. The mean age of the subjects was 26.2 +/- 10.7 years; 57.3% were female; and 72.0% were white. The mean preoperative and postoperative estimates of difficulty were 44.3 +/- 23.4 and 39.6 +/- 24.7 mm, respectively. The mean absolute and actual differences between preoperative and postoperative estimates were 15.7 +/- 13.6 and 4.8 +/- 20.2 mm, respectively. We identified several demographic and anatomic variables statistically associated ( P < or = .05) with error in estimating difficulty. CONCLUSIONS: Our models indicate that errors in the estimates of difficulty were related to demographic (age, gender, ethnicity, snoring) and anatomic (cheek flexibility, mouth opening) variables, with little or no dependence on radiographic variables or surgical experience.

Adolescent↗
PubMed2000

EEG operant conditioning (biofeedback) and traumatic brain injury.

A review is presented of the currently sparse literature about EEG operant conditioning or biofeedback as a treatment to reduce symptomology and patient complaints following a traumatic brain injury. The paper also evaluates the general use of quantitative EEG (QEEG) to assess traumatic brain injury and to facilitate EEG biofeedback treatment. The use of an age matched reference normative QEEG database and QEEG discriminant function are presented as a method to evaluate the nature or neurological basis of a patient's complaints as well as to individualize an efficient and optimal feedback protocol and to help evaluate the efficacy of the biofeedback therapy. Univariate and multivariate statistical issues are discussed, different classes of experimental designs are described and then a "double blind" research study is proposed in an effort to encourage future research in the area of EEG biofeedback for the treatment and rehabilitation of traumatic brain injury.

Analysis of Variance↗
PubMed1997

Early outcome assessment for 2228 consecutive carotid endarterectomy procedures: the Cleveland Clinic experience from 1989 to 1995.

PURPOSE: Several randomized trials now have established guidelines regarding patient selection for carotid endarterectomy (CEA) that have been widely accepted but have little relevance unless they are considered in the context of perioperative risk. The purpose of this study was to demonstrate the feasibility of early outcome assessment using a computerized database. METHODS: Since 1989 demographic information and in-hospital results for all surgical procedures performed by the members of our department have been entered into a prospective registry. For the purpose of this report, we have analyzed the stroke and mortality rates for 2228 consecutive CEAs (2046 patients), including 1924 that were performed as isolated operations and 304 that were combined with simultaneous coronary artery bypass grafting (CABG). This series incidentally contains a total of 153 reoperations for recurrent carotid stenosis. RESULTS: The respective stroke and mortality rates were 0.5% and 1.8% for all isolated CEAs, 4.3% and 5.3% for all CEA-CABG procedures, and 4.6% and 2.0% for carotid reoperations. According to a multivariable statistical model, the composite stroke and mortality rate for isolated CEA was significantly influenced by female gender (p = 0.050), by the urgency of intervention (p = 0.026), and by carotid reoperations (p = 0.024). Gender (p = 0.030) and urgency (p = 0.040) also were associated with differences in the stroke rate alone; furthermore, the incidence of perioperative stroke was higher in conjunction with synthetic patching (odds ratio, 2.6; 95% confidence interval, 1.2 to 5.3) and was marginally higher with primary arteriotomy closure (odds ratio, 2.7; 95% confidence interval, 0.8 to 9.5) compared with vein patch angioplasty (1.3%). The method used to repair the arteriotomy was the only independent factor that qualified for the multivariable composite stroke and mortality models that were applied to the combined CEA-CABG procedures, but too few patients in this cohort had synthetic patches or primary closure to validate the perceived superiority of vein patching. CONCLUSIONS: Prospective outcome assessment is essential to reconcile the indications for CEA with its actual results, and it may lead incidentally to important observations concerning patient care.

Adult↗
PubMed2006

A taxonomic analysis of sleep stages.

STUDY OBJECTIVES: To study the structure of human sleep at the level of sleep stages. We applied taxonomic statistics to detect significant configurations (types) of different physiologic variables and their relationship to sleep stages. DESIGN AND STATISTICS: Polygraphic sleep recordings from 32 subjects (normal sleepers as well as patients with insomnia, sleep apnea, or narcolepsy; n = 8 per group) were visually scored and submitted to a configural frequency analysis. The configural frequency analysis was computed with 3 continuous input variables: an electroencephalogram parameter, which represents the point of gravity of the EEG frequency distribution; the alpha slow-wave index, and the Rest Index, based on the presence or absence of phasic electromyographic activity. These variables were dichotomized for further analysis. The combination of 2 levels ( + or -) and 3 variables resulted in 2(3) patterns ( +++ to - - - ). The configural frequency analysis is a nonparametric X2-type multivariate statistic that identifies significant patterns or types. RESULTS: Each sleep stage contained 3 or 4 types. For non-rapid eye movement sleep stages 2, 3, and 4, types overlapped, whereas there was no overlap of types between stages 1 and 2. Types of rapid eye movement sleep did not overlap with those from stages 2, 3, and 4 but did overlap with wake and stage 1 types. The majority of observed types were significant in all 4 groups of subjects. CONCLUSIONS: Sleep stages appear to be less homogenous than rule-based sleep scoring would suggest. Types were either restricted to one stage or overlapped with neighboring stages.

Adult↗
PubMed1992

Two-dimensional crystals of Escherichia coli maltoporin and their interaction with the maltose-binding protein.

We have reconstituted Escherichia coli maltoporin into phospholipid membranes at low lipid-to-protein ratios to produce two-dimensional crystals of this membrane protein. Electron microscopy of negatively stained membranes showed three different types of arrays, two of them hexagonal and the third rectangular, all diffracting to approximately (2 nm)-1. Furthermore, we have core-constituted maltoporin with the maltose-binding protein from E. coli, a soluble periplasmic protein that has been proposed to interact with maltoporin. One of the hexagonal arrays was found to bind maltose-binding protein molecules in a regular way, while the maltose-binding protein binding sites were not accessible in the other crystal forms. Difference maps from averaged decorated arrays and undecorated controls showed three symmetry-related maltose-binding protein binding sites per maltoporin trimer, of which not more than one is likely to be occupied at a given time. Using multivariate statistical analysis to select similar unit cells of the decorated maltoporin array, we have obtained a map showing the rough outline of a maltose-binding protein molecule interacting with the pore formed by a maltoporin trimer.

ATP-Binding Cassette Transporters↗
PubMed1993

Flopping polypeptide chains and Suleika's subtle imperfections: analysis of variations in the electron micrograph of a purple membrane crystal.

Patch averaging, a method of data analysis combining correlation averaging with multivariate statistical analysis, was applied to a high-resolution image of a purple membrane thin crystal. The observed variational patterns fall in two categories: non-crystallographic, related to small electron-optical distortions of the microscope, and crystallographic, conceivably related to variations in the locations of flexible segments of the polypeptide chain on the surface of the membrane.

Bacteriorhodopsins↗
PubMed2005

Is there a role for reconstructive techniques to prevent periodontal defects after third molar surgery?

PURPOSE: Among patients at high risk for second molar (M2) periodontal defects after third molar (M3) removal, does active treatment at the time of extraction, when compared with no treatment, alter the risk of postextraction M2 periodontal defects? MATERIALS AND METHODS: We used a prospective cohort study design and a sample composed of subjects at high risk for developing M2 periodontal defects after M3 extraction, that is, age > or = 26 years, pre-existing periodontal defects (attachment level [AL] > or = 3 mm), and mesioangular or horizontal M3 impaction. The predictor variable was treatment status of the M3 extraction site. The M3 extraction sites were reconstructed with demineralized bone powder (DBP), bioresorbable guided tissue regeneration (GTR) therapy, or no treatment. The outcome variable was ALs measured at the M2 distobuccal line angle preoperatively and 26 weeks after extraction. Appropriate univariate, bivariate, and multivariate statistics were computed, and statistical significance was set at a value P < .05. RESULTS: The cohort was composed of 12 subjects contributing 18 high-risk M3s. Twenty-six weeks after M3 removal, the ALs for GTR-treated (3.0 +/- 1.2 mm), DBP-treated (1.4 +/- 0.5 mm), and control (3.8 +/- 0.9) M3 sites were statistically significantly different ( P = .002). Tukey post-hoc comparisons revealed a statistically significant difference between control and DBP ALs ( P = .001) and GTR-treated and DBP-treated ALs ( P = .037). There was no statistically significant difference in ALs between control and GTR-treated M3s ( P = .35). CONCLUSIONS: The results of this study suggest that subjects at high risk for developing M2 periodontal defects after M3 removal may benefit from the use of DBP placed at the time of M3 extraction to enhance periodontal healing.

Adult↗
PubMed2006

Effects of growth conditions and processing on Rehmannia glutinosa using fingerprint strategy.

Metabolite profiling in combination with multivariate statistics is a sophisticated method for quality assessment of natural products. For the development of a quality control strategy in Traditional Chinese Medicine (TCM), we have measured the metabolite fingerprints of Rehmannia glutinosa by GC-MS. Plants were grown under different climate and soil conditions in a phytotron and were processed by a variable number of repetitive steps to investigate the effects on both growth conditions and processing for material medica of R. glutinosa. The GC-MS data have been analyzed by principal component analysis (PCA) and the new approach of the ANOVA-simultaneous component analysis (ASCA) which can combine the information from a structured data design with multivariate analysis. The results clearly show the effect of the different factors and indicate directions for process improvement. When plants were grown under various temperatures, humidity and light intensities for a short period (3 weeks), no significant changes on studied metabolites were observed. However, significant changes were found between different processing cycles. The present data clearly indicate the importance of strictly controlling processing in R. glutinosa and illustrate the impact of growth conditions. This is the first report on the metabolite profile of R. glutinosa that provides a base for the establishment of a quality control strategy.

Climate↗
PubMed2001

Chimera analysis of the Clock mutation in mice shows that complex cellular integration determines circadian behavior.

The Clock mutation lengthens periodicity and reduces amplitude of circadian rhythms in mice. The effects of Clock are cell intrinsic and can be observed at the level of single neurons in the suprachiasmatic nucleus. To address how cells of contrasting genotype functionally interact in vivo to control circadian behavior, we have analyzed a series of Clock mutant mouse aggregation chimeras. Circadian behavior in Clock/Clock <--> wild-type chimeric individuals was determined by the proportion of mutant versus normal cells. Significantly, a number of intermediate phenotypes, including Clock/+ phenocopies and novel combinations of the parental behavioral characteristics, were seen in balanced chimeras. Multivariate statistical techniques were used to quantitatively analyze relationships among circadian period, amplitude, and suprachiasmatic nucleus composition. Together, our results demonstrate that complex integration of cellular phenotypes determines the generation and expression of coherent circadian rhythms at the organismal level.

Animals↗
PubMed2003

Shape differences rather than size differences between castes in the Neotropical swarm-founding wasp Metapolybia docilis (Hymenoptera: Vespidae, Epiponini).

BACKGROUND: Swarm-founding epiponine wasps are an intriguing group of social insects in which colonies are polygynic (several queens share reproduction) and differentiation between castes is often not obvious. However, caste differences in some may be more pronounced in later phases of the colony cycle. RESULTS: Using morphometric analyses and multivariate statistics, it was found that caste differences in Metapolybia docilis are slight but more distinct in latter stages of the colony cycle. CONCLUSIONS: Because differences in body parts are so slight, it is proposed that such variation may be due to differential growth rates of body parts rather than to queens being larger in size, similar to other previously observed epiponines.

Animals↗
PubMed2003

Predictors of attrition in a large clinic-based weight-loss program.

OBJECTIVE: Identifying client factors that predict dropout is critical for the development of effective weight-loss programs. Although demographic predictors are studied, there are few consistent findings. The purpose of this study was to identify predictors of dropout in a large clinic-based weight-loss program using readily attainable demographic variables. RESEARCH METHODS AND PROCEDURES: All 866 weight-loss patients in a clinic-based weight-loss program enrolled during 1998 to 1999 were followed. Attrition and retention rates were measured at 8 and 16 weeks. Six variables (sex, race, marital status, age, BMI, and treatment protocol) were evaluated using bivariate and multivariable statistics for relative association with dropout. RESULTS: The overall attrition rate for the 16-week program was 31%. The retention rate was 69%. Significant risk for dropout, measured as bivariate relative risk (95% confidence interval), was found among patients who were: females, 1.32 (1.01 to 1.73); divorced, 1.54 (1.13 to 2.09); African Americans, 1.68 (1.26 to 2.23); age < 40, 1.66 (1.27 to 2.18); and ages 40 to 50, 1.33 (1.01 to 1.76). There were no significant differences in retention rates by BMI group or program protocol. After logistic regression analysis to control for all variables, young age < 50 years had the only significant association with dropout [odds ratio = 1.39 (1.02 to 1.90)]. DISCUSSION: Multivariable modeling was helpful for prioritizing risk factors for program dropout. These findings have important implications for improving weight-loss program effectiveness and reducing attrition. By knowing the groups at risk for dropout, we can improve or target program treatments to these populations.

Adult↗
PubMed1995

Controlling for confounding by indication for treatment. Are administrative data equivalent to clinical data?

There has been controversy about whether confounding by indication for treatment--that is, owing to physicians' conscious efforts to base treatment decisions on patients' pretreatment prognoses--makes nonrandomized, observational comparisons of treatments invalid. Some now believe evidence from studies of practice variation means that physicians' treatment decisions have little relationship to patients' prognostic clinical characteristics. They therefore believe that patients who receive different treatments should vary little in their baseline prognoses, and multivariable statistical methods should easily be able to adjust for any resultant confounding, even when analyses are restricted to administrative rather than clinical data. The objective of this study is to determine whether adjusting for variables found in administrative data sets produces the same results as does adjusting for clinical variables. Data were reanalyzed from a previously enrolled prospective sequential cohort of 227 hospitalized patients with suspected bacteremia who had blood cultures. The treatment under study was aminoglycoside therapy given empirically, that is, before blood culture results were known. The outcome of interest was death during hospitalization. Univariable analyses suggest that empiric aminoglycoside therapy had a positive association with mortality, by univarible logistic regression, odds ratio (OR = 3.1 (95% confidence interval = [1.6, 5.8]). Few administrative variables had univariable associations with aminoglycoside use or death. Multivariable analyses that controlled for them still suggest that aminoglycosides increased mortality; for example, in one model, adjusted OR = 3.2 (1.6, 6.5). Many clinical variables were strongly associated with aminoglycoside use or death. Analyses that controlled for them suggested that empiric aminoglycosides did not increase mortality; for example, in one model, adjusted OR = 1.2 (0.55, 2.7.) Results of adjustment for confounding using administrative data disagreed with the results of adjustment using clinical data. It is concluded that nonrandomized, observational outcome studies that fail to control for prognostic differences between patients receiving different treatments may not always be valid.

APACHE↗
PubMedDate not supplied

Epidemiological characteristics of Schistosoma mansoni infection in rural and urban endemic areas of Minas Gerais, Brazil.

To compare the epidemiological profile and socioeconomic factors associated to the infection by Schistosoma mansoni in a rural and an urban endemic area a cross-sectional study was performed in Agua Branca de Minas (rural area) and Bela Fama (urban area), both situated in the State of Minas Gerais, Brazil. Two hundred and eighty eight individuals were surveyed in the rural area and 787 in the urban area. Water contact and socioeconomic questionnaires were used to identify risk factors for the infection. The prevalences of 38.8% and 9.7% and the geometric mean of eggs per gram of faeces of 117.8 and 62.3 were found in the rural and urban areas, respectively. By multivariate statistical analysis age groups over nine years old and previous specific treatment were associated with the infection in rural area. In urban area age over nine years old, low quality housing, weekly fishing and swimming were associated after adjustment by logistic regression.

Adolescent↗
PubMed2002

Concurrent arterial aneurysms in brain arteriovenous malformations with haemorrhagic presentation.

OBJECTIVE: To assess the effect of concurrent arterial aneurysms on the risk of incident haemorrhage from brain arteriovenous malformations (AVMs). METHODS: In a cross sectional study, 463 consecutive, prospectively enrolled patients from the Columbia AVM Databank were analysed. Concurrent arterial aneurysms on brain angiography were classified as feeding artery aneurysms, intranidal aneurysms, and aneurysms unrelated to blood flow to the AVM. Clinical presentation (diagnostic event) was categorised as intracranial haemorrhage proved by imaging or non-haemorrhagic presentation. Univariate and multivariate statistical models were applied to test the effect of age, sex, AVM size, venous drainage pattern, and the three types of aneurysms on the risk of AVM haemorrhage at initial presentation. RESULTS: Arterial aneurysms were found in 117 (25%) patients with AVM (54 had feeding artery aneurysms, 21 had intranidal aneurysms, 18 had unrelated aneurysms, and 24 had more than one aneurysm type). Intracranial haemorrhage was the presenting symptom in 204 (44%) patients with AVM. In the univariate model, the relative risk for haemorrhagic AVM presentation was 2.28 (95% confidence interval (CI) 1.12 to 4.64) for patients with intranidal aneurysms and 1.88 (95% CI 1.14 to 3.08) for those with feeding artery aneurysms. In the multivariate model an independent effect of feeding artery aneurysms (odds ratio 2.11, 95% CI 1.18 to 3.78) on haemorrhagic AVM presentation was found. No significant effect was seen for intranidal and unrelated aneurysms. The attributable risk of feeding artery aneurysms for incident haemorrhage in patients with AVM was 6% (95% CI 1% to 11%). CONCLUSIONS: The findings suggest that feeding artery aneurysms are an independent determinant for increased risk of incident AVM haemorrhage.

Adult↗
PubMed1992

Administration of oral chloral hydrate to paediatric patients undergoing magnetic resonance imaging.

Sedation is frequently required in children undergoing magnetic resonance imaging (MRI). 172 Paediatric patients (82 female and 90 male, age 42 +/- 26 months, weight 14.7 +/- 5.6 kg) entered an open, non-comparative, prospective study to assess the utilization of oral chloral hydrate. Chloral hydrate syrup (70 mg/ml) was administered 20-30 min prior to the procedure. Effective sedation was reached in 80.3% with an average initial dose of 55 mg/kg and in 93.6% with an average total dose of 65 mg/kg. Significant differences in effectivity were correlated with the dose (54 +/- 11 mg/kg in failure cases versus 66 +/- 16 mg/kg in effective cases; p < 0.05) and diagnosis (effectivity falls to 62.5% and 76.0% in children with medullar tumours and encephalic white matter alterations, respectively; p < 0.01). Average sleep induction time was 30 +/- 19 min, and average duration of sleep was 62 +/- 24 min. Adverse reactions occurred in 4.7%, with nausea, vomiting and stomach pain being the most common side-effects (3.5%). Multivariate statistical analysis selects total dose and age into the discriminant function, with a 100% relative percentage of correct classification. A simple method for optimizing the chloral hydrate dose in children is proposed: the dose in mg/kg is calculated as half the age in months + 50.

Administration, Oral↗
PubMed1994

Measuring feeding difficulty in patients with dementia: multivariate analysis of feeding problems, nursing intervention and indicators of feeding difficulty.

The feeding difficulty of 196 elderly people with dementia was investigated by means of an 11-item questionnaire administered to nursing staff. The questionnaire was analysed by means of multivariate statistics, namely factor analysis. The factor analysis demonstrated that the original items could be reduced to three factors. These three factors were named: (a) patient obstinacy or passivity; (b) nursing intervention; and (c) indicator of feeding difficulty. This quantitative analysis confirms a previous qualitative distinction between items in the questionnaire and suggests avenues of research into the relationship between the factors.

Aged↗