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PubMedDate not supplied

[Prospective study of the therapeutic usefulness and safety of a new disposable intraurethral occlusive device (Uriabsorber) for female stress urinary incontinence].

OBJECTIVES: To determine the therapeutic usefulness and side effects of a new disposable intraurethral device (Uriabsorber) for female stress urinary incontinence. METHODS: A prospective study was performed in a cohort of 48 women (mean age 42.7 yr.) consulting because of urinary incontinence with coughing. Lack of manual ability or difficulty to understand, pregnancy, puerperium, vaginitis, urinary tract infection and current administration of active treatment for urinary incontinence were all exclusion criteria. Patients were instructed about the use of the device. Two visits were performed: one after two weeks and the other at the end of the month. Clinical results were collected and urine analysis was performed. A multivariate statistical analysis was performed to determine what variables influenced the final result. RESULTS: Treatment withdrawal rate was 42% after one month, being most withdrawals before 14 days (19 cases, 40%). The causes of withdrawal were local discomfort (11 cases, 23%) and difficult insertion (3 cases, 6%). There were only five cases (10%) of urinary tract infection, and two cases (4%) of macroscopic hematuria. The presence of cystocele was associated with higher frequency of complications (80%). 79% of the patients completing the month of treatment had positive results (50% resolution of incontinence and 29% improvement). Multivariate statistical analysis showed that variables independently influencing the results were: incontinence intensity (the lower the intensity, the better the results), presence of urinary tract symptoms (the lower the intensity of the symptoms, the better the results), and absence of past history of pathology. CONCLUSIONS: The intraurethral disposable device significantly reduces the rate of urinary tract infections. Tolerance depends on the ability and motivation of the patients. It is indicated in the control of non intense urinary incontinence in motivated patients, without evident cystocele.

Adult↗
PubMed2001

Prognostic factors in surgically treated stage ib-iib cervical carcinomas with special emphasis on the importance of tumor volume.

OBJECTIVE: The aim of the study was to analyze the importance of tumor volume as a prognostic factor for overall survival (OS) in surgically treated stage Ib-IIb cervical carcinoma. METHODS: One hundred thirteen of one hundred sixty-five patients with histopathological stage Ib-IIb cervical carcinoma (44 Ib1, 24 Ib2, 10 IIa, 35 IIb) treated by radical abdominal hysterectomy between 1989 and 1999, for whom tumor volume could be assessed, were included in this study. Of the 113 patients, 90 (79.6%) received postoperative radiotherapy. Measurement of tumor volume was performed on giant histological sections using a semiautomatic image analyzer. The prognostic significance of tumor volume was analyzed and compared with that of various clinicopathological parameters using uni- and multivariate statistics. RESULTS: The 5-year disease-free survival was 71.4%. Increasing tumor volume was associated with more frequent lymph node metastases and a significant decrease in OS (P = 0.0112). The Median tumor volume was smaller in stage IIa tumors than in stage Ib2 tumors, and histopathological stage did not correlate linearly with lymph node metastases as well as OS. Stage Ib2 tumors were associated with worse overall survival than stage IIa tumors. In univariate analysis, lymph node metastases, histopathological stage, lymph vascular space involvement, tumor volume, parametrial spread, and tumor involvement of resection margins were significant parameters for OS. In multivariate statistical analysis, only lymph node metastases and histopathological staging remained independent prognostic factors for OS. CONCLUSIONS: Tumor volume does not seem to confer additional prognostic information if histopathological stage and lymph node status are known. However, it may provide important prognostic information if lymph node status is not known or histopathological stage cannot be assessed.

Adenocarcinoma↗
PubMed2003

Assessment of the surface water quality in Northern Greece.

The application of different multivariate statistical approaches for the interpretation of a large and complex data matrix obtained during a monitoring program of surface waters in Northern Greece is presented in this study. The dataset consists of analytical results from a 3-yr survey conducted in the major river systems (Aliakmon, Axios, Gallikos, Loudias and Strymon) as well as streams, tributaries and ditches. Twenty-seven parameters have been monitored on 25 key sampling sites on monthly basis (total of 22,350 observations). The dataset was treated using cluster analysis (CA), principal component analysis and multiple regression analysis on principal components. CA showed four different groups of similarity between the sampling sites reflecting the different physicochemical characteristics and pollution levels of the studied water systems. Six latent factors were identified as responsible for the data structure explaining 90% of the total variance of the dataset and are conditionally named organic, nutrient, physicochemical, weathering, soil-leaching and toxic-anthropogenic factors. A multivariate receptor model was also applied for source apportionment estimating the contribution of identified sources to the concentration of the physicochemical parameters. This study presents the necessity and usefulness of multivariate statistical assessment of large and complex databases in order to get better information about the quality of surface water, the design of sampling and analytical protocols and the effective pollution control/management of the surface waters.

Environmental Monitoring↗
PubMed1989

Function after total hip replacement for primary osteoarthritis.

We have reviewed 505 cases of surviving total hip replacement for primary osteoarthritis and studied the functional result and pain relief obtained between four and fourteen years after implantation. The risk factors were stratified and evaluated by multivariate statistical analysis. The patients were satisfied with the result of arthroplasty, and long-term function was improved in 95% of cases. The risk of postoperative hip pain was increased by knee pain, a snap-fit prosthesis with a 35 mm head, and a short wedge-shaped femoral stem, and by replacement at an early age. Function was impaired postoperatively by hip pain, bilateral hip disorders, intercurrent disease affecting locomotion and by old age at the time of surgery. The functional result was not related to the time from operation. The functional result after hip arthroplasty can be evaluated in a logical, unbiased and thorough way using multivariate statistical analysis.

Activities of Daily Living↗
PubMed1995

Flash visual evoked potential (VEP) in amblyopia and optic nerve disease.

Amblyopia and optic atrophy are two very different causes of unilateral long-standing visual impairment. Yet, in some patients the differential diagnosis is not always manifest and standard clinical tests may fail to provide accurate information. We tested the efficacy of a nonstandard clinical test [flash visual evoked potentials (VEP's)] and quantitative multivariate statistical techniques as aids in the assessment of this differential. Thirty-three patients were separated into four groups (normal, anisometropic amblyopia, strabismic amblyopia, and unilateral optic atrophy). Non-patterned flash VEP's were obtained using several different temporal frequency rates. Patients with optic atrophy had significantly reduced VEP's in the affected eye at all temporal frequencies. Strabismic amblyopes, but not anisometropic amblyopes, often showed supranormal responses in the affected eye at the higher temporal frequencies. Finally, by using discriminant analysis (DA) we were able to classify correctly almost 70% of the patients, well above chance level of 25%. This DA provided very good sensitivity and specificity. We have shown that the use of flash VEP's and of multivariate statistical techniques may provide an effective way to diagnose amblyopia differentially from optic atrophy.

Amblyopia↗
PubMed1995

Effects of K(+)-induced depolarization and purinergic receptor activation on elemental content in insulin-producing RINm5F-cells.

X-ray microanalysis was used to detect elemental changes in the insulin-producing tumor cell-line RINm5F. To improve discrimination between mobile ions and ions bound to macromolecules a new approach was employed, consisting of multivariate statistical analysis of correlations between the concentrations of Na, Mg, P, S, Cl, K, and Ca. RINm5F cells, cultured on Formvar-coated titanium grids, were stimulated with high K+ or ATP, that are both known to stimulate insulin release. The buffers used contained Ca2+ or one of the Ca(2+)-analogues Sr2+ and Ba2+, to represent Ca2+ uptake in response to stimulation. After stimulation the cells were shock-frozen and freeze-dried overnight. Incubation for 10-20 seconds in a Ca(2+)-containing buffer did not significantly affect elemental composition, whereas cellular Mg, P and K decreased in a Sr(2+)-containing buffer. Depolarization with high K+ concentration caused an increase in the cellular Na content, both in Ca(2+)- and Sr(2+)-containing buffers, but not in the buffer where Ca2+ had been replaced by Ba2+. X-ray microanalysis is useful for detection of elemental changes subsequent to stimulation of cultured cells. Moreover, multivariate statistical analysis strengthens the idea that stimulation of RINm5F cells causes redistribution of ions possibly due to changes in the state of binding of some elements to cellular proteins.

Adenosine Triphosphate↗
PubMed1994

The identification of pathological subtypes of Alzheimer's disease using cluster analysis.

A cluster analysis was performed on 78 cases of Alzheimer's disease (AD) to identify possible pathological subtypes of the disease. Data on 47 neuropathological variables, including features of the gross brain and the density and distribution of senile plaques (SP) and neurofibrillary tangles (NFT) were used to describe each case. Cluster analysis is a multivariate statistical method which combines together in groups, AD cases with the most similar neuropathological characteristics. The majority of cases (83%) were clustered into five such groups. The analysis suggested that an initial division of the 78 cases could be made into two major groups: (1) a large group (68%) in which the distribution of SP and NFT was restricted to a relatively small number of brain regions, and (2) a smaller group (15%) in which the lesions were more widely disseminated throughout the neocortex. Each of these groups could be subdivided on the degree of capillary amyloid angiopathy (CAA) present. In addition, those cases with a restricted development of SP/NFT and CAA could be divided further into an early and a late onset form. Familial AD cases did not cluster as a separate group but were either distributed between four of the five groups or were cases with unique combinations of pathological features not closely related to any of the groups. It was concluded that multivariate statistical methods may be of value in the classification of AD into subtypes.

Aged↗
PubMed2003

What affects mRNA levels in leaves of field-grown aspen? A study of developmental and environmental influences.

We have analyzed the abundance of mRNAs expressed from 11 nuclear genes in leaves of a free-growing aspen (Populus tremula) tree throughout the growing season. We used multivariate statistics to determine the influence of environmental factors (i.e. the weather before sampling) and developmental responses to seasonal changes at the mRNA level for each of these genes. The gene encoding a germin-like protein was only expressed early in the season, whereas the other tested genes were expressed throughout the season and showed mRNA variations on a day-to-day basis. For six of the genes, reliable models were found that described the mRNA level as a function of weather, but the leaf age was also important for all genes except one encoding an early light-inducible protein (which appeared to be regulated purely by environmental factors under these conditions). The results confirmed the importance of several environmental factors previously shown to regulate the genes, but we also detected a number of less obvious factors (such as the variation in weather parameters and the weather of the previous day) that correlated with the mRNA levels of individual genes. The study shows the power of multivariate statistical methods in analyzing gene regulation under field conditions.

Gene Expression Regulation, Developmental↗
PubMed1986

Effects of altitude, ethnicity-religion, geographical distance, and occupation on adult anthropometric characters of eastern Himalayan populations.

With a view to estimating the effect of altitude on body dimensions vis-à-vis ethnicity-religion, geographical distance, and occupation, a comprehensive multivariate statistical analysis was performed on data pertaining to 16 anthropometric characters collected from 1,103 individuals (643 males and 460 females) belonging to two ethnic groups-Sherpa and Lepcha. Samples were drawn from several locations in the eastern Himalayan region-Darjeeling and Kalimpong in West Bengal (India), and Nepal, situated at low (1,000-2,000 meters) and high (above 3,500 meters) altitudes. The individuals sampled practice different occupations and follow different religions. Significant age and sex effects were observed. The data were age-adjusted, and sexes were treated separately. A test of equality of mean vectors indicated heterogeneity among population groups. Almost all characters were found to contribute significantly to the ability to discriminate between the groups. The overall probability of correctly classifying an individual based on body dimensions into the group in which she or he actually belongs was high (between 0.64 and 0.77). Shape and size factors could be identified that explained about 50% of the total variance and yielded a reasonable separation of the groups. Results of four different types of multivariate statistical analyses were in agreement, and showed that altitude is most highly associated with body dimensions.

Adult↗
PubMed1995

Influence of three factors on the diagnostic effectiveness of transthoracic needle aspiration in pneumonia.

Prior antibiotic therapy, size of the infiltrate, and the person who performed the technique were the three factors that we studied to assess their influence on the effectiveness of transthoracic needle aspiration (TNA). Ninety-one patients with a diagnosis of severe bacterial pneumonia, who underwent TNA, have been included in the study. The technique was carried out with an ultrathin needle gauge 25 and without fluoroscopic control. A univariate (UA) and a multivariate statistical analysis were made. The sensitivity of TNA was 34.1%. Fifty-seven of 91 (62.6%) had received antibiotic therapy prior to TNA; sensitivity was higher in nontreated patients than in treated patients (p = 0.0033; UA). There were 34 patients with an infiltrate that was smaller than a lobe (MINLOB); 39 cases affected a complete lobe (LOB) and 18 more than one lobe (MAJLOB). The TNA sensitivity was higher in LOB cases than in MINLOB cases (p = 0.0004; UA) while when comparing LOB cases and MAJLOB cases, sensitivity was higher in the former (p = NS; UA). In 28 of 91 cases (30.8%), the TNA was performed by A (a trained physician who regularly carries out the technique) and in 63 of 91 cases (69.2%) by B (other physicians, 10 in our study, who sporadically perform the technique). The TNA sensitivity was higher when the technique was performed by A, although this difference was not significant; if we add negative TNA with leukocytes present in Gram stains (which would indicate that aspiration was done in the correct area) to positive TNA, the difference between A and B was higher (p = 0.0248). The multivariate statistical analysis confirmed that there are two variables that are independently connected to a positive TNA (prior antibiotic therapy and size of the infiltrate). As regards the variable "person who carries out the technique," a significant association with a positive TNA was not established, although the estimations we obtained show a possible clinical relevance.

Adult↗
PubMed2000

Topography of clonidine-induced electroencephalographic changes evaluated by principal component analysis.

BACKGROUND: Principal component analysis is a multivariate statistical technique to facilitate the evaluation of complex data dimensions. In this study, principle component analysis was used to reduce the large number of variables from multichannel electroencephalographic recordings to a few components describing changes of spatial brain electric activity after intravenous clonidine. METHODS: Seven healthy volunteers (age, 26 +/- 3 [SD] yr) were included in a double-blind crossover study with intravenous clonidine (1.5 and 3.0 microg/kg). A spontaneous electroencephalogram was recorded by 26 leads and quantified by standard fast Fourier transformation in the delta, theta, alpha, and beta bands. Principle component analysis derived from a correlation matrix calculated between all electroencephalographic leads (26 x 26 leads) separately within each classic frequency band. The basic application level of principle component analysis resulted in components representing clusters of electrodes positions that were differently affected by clonidine. Subjective criteria of drowsiness and anxiety were rated by visual analog scales. RESULTS: Topography of clonidine-induced electroencephalographic changes could be attributed to two independent spatial components in each classic frequency band, explaining at least 85% of total variance. The most prominent effects of clonidine were increases in the delta band over centroparietooiccipital areas and decreases in the alpha band over parietooccipital regions. Clonidine administration resulted in subjective drowsiness. CONCLUSIONS: Data from the current study supported the fact that spatial principle component analysis is a useful multivariate statistical procedure to evaluate significant signal changes from multichannel electroencephalographic recordings and to describe the topography of the effects. The clonidine-related changes seen here were most probably results of its sedative effects.

Adult↗
PubMed1993

Differential activation and classification of cutaneous afferents in the rat.

1. A total of 312 cutaneous afferent units identified in the rat foot as belonging to one of nine major types of sensory receptors were included in the present study. A natural stimulus set was defined to differentiate optimally among those receptor types according to the distinguishing response patterns that it produced. It included air puffs, 30- and 300-Hz sinusoids, 200-mN force indentation of the skin, 1.2- and 6-N compressions of a skin fold, cooling the skin by 5 and 20 degrees C, warming by 5 degrees C, and heating by 15 degrees C. 2. The responses to predefined stimuli of 188 units were subjected to multivariate statistical analyses. The responses of an individual unit were measured as the number of impulses evoked by 10 stimuli, each lasting 10 s. Additionally, the number of impulses occurring for 5 s after withdrawal of a 200-mN indentation (1 of the 10 stimuli) was counted. 3. In discriminant analysis, the 11 stimulus variables predicted fairly correctly the grouping of afferent units into nine predetermined receptor categories (175 of 188, 93.1%), indicating a powerful ability to discriminate among different receptor types. Using hierarchical cluster analysis, afferent unit data described by 11 variables were divided into clusters that well represented prior receptor categories (170 of 188, 90.4%), suggesting the reliable application of this procedure to the classification of newly recorded cutaneous sensory receptors. 4. Eleven variables were then reduced to 7 on the basis of the results of factor analysis (95% of variance accounted for). The seven variables corresponded to 1.2-N compression, heating the skin by 15 degrees C, cooling the skin by 20 degrees C, 30- and 300-Hz sinusoids, withdrawal of a 200-mN indentation, and air puffs. 5. The seven selected variables correctly assigned afferent units into five modality-based categories in the discriminant solution (177 of 188, 94.1%). In the cluster solution, afferent units described by the seven selected variables were divided into clusters, most of whose members were modality specific (176 of 188, 93.6%). 6. The results indicate that cutaneous receptors can be divided into modality-specific groups according to similarities in their responses to seven stimulus variables. It is proposed that the stimulus set developed here and multivariate statistical methods can be used as powerful tools for the functional classification of central somatosensory neurons.

Afferent Pathways↗
PubMedDate not supplied

Use of TLC and multivariate mathematical statistical methods to study the interaction of monoamine oxidase inhibitory drugs with amino acids.

The interaction of 17 monoamine oxidase inhibitory drugs (propargylamine derivatives) with amino acids was studied by charge-transfer chromatography. The data set was evaluated by principal component analysis (PCA). To assess the effect of the information loss caused by normalization, PCA was separately carried out on the covariance and on the correlation matrix. The strength and selectivity of interaction was separated by the spectral mapping technique. Calculation proved that the amino group of the drugs interacted with the second carboxyl group of dicarboxylic amino acids, and that the interaction was of electrostatic character. This finding made probable the direct interaction between the drugs and the target enzyme or enzymes. The results of both PCA methods were similar. However, coordinates of the spectral map showed only slight correlation with the corresponding coordinates of the two-dimensional nonlinear maps proving the different information content of the methods.

Amino Acids↗
PubMed2000

Do undefined sources of hepatitis C transmission exist? The Greek study in General Practice.

A seroepidemiological study was carried out in 15 primary health care (PHC) centres in rural Greece to determine the prevalence of hepatitis C virus (HCV) in the surgeries of Greek General Practitioners (GPs) and to further clarify the transmission of hepatitis C in Greece. Serum samples were obtained from 1961 subjects (1259 females) aged >/= 15 years, who visited GP surgeries between July 1996 and February 1997 in 15 PHC centres located in three large Greek regions (Macedonia, Attika and Crete). Subjects who participated in the study fulfilled the following criteria: history of blood transfusion; hospital admission of > 7 days' duration without surgical or other intervention; use of intravenous drugs (current or previous); or women with a history of medical or paramedical abortion. Nearly 65% (1263 subjects) of the participants in this study reported hospital admission with a length of stay > 7 days. Antibodies to HCV (anti-HCV) were found in 67 participants (3. 5%), 41 of whom were females and 44 of whom were aged >/= 61 years. The highest prevalence (4.8%) of anti-HCV was found in Crete, and differences among the Greek regions were statistically significant (P < 0.05). Multivariate statistical analysis showed that in addition to regional differences, the following variables had a statistically significant effect on the prevalence of anti-HCV: history of dental surgery; use of intravenous drugs; hospital admission for > 7 days; and the high consumption of alcoholic drinks. Hence there is a significant variability in the prevalence of hepatitis C in well-defined PHC areas of Greece. Several risk factors for acquiring HCV infection have been identified. Screening for HCV risk factors may enable Greek GPs to identify HCV-infected patients.

Adolescent↗
PubMed1985

[Long-term prognosis of drug and surgery treated patients with acquired aortic valve diseases: survival statistics and multivariate Cox regression analysis].

Data of 417 patients with advanced chronic aortic valve disease were retrospectively analyzed using a life table and Cox regression analysis. Aortic valve replacement was recommended to all patients based on clinical and hemodynamic findings. While most patients underwent prosthetic aortic valve replacement (n = 349), a minority of patients was treated medically (n = 68). Prognosis was better (p less than 0.01 in the Cox model) in surgically treated as compared to medically treated patients with aortic stenosis (4-year survival rate 82 versus 44%). In patients with aortic insufficiency no significant difference of long-term prognosis was found between surgically and medically treated patients.

Anti-Bacterial Agents↗
PubMed1980

[Reliability of statistical methods in anthropology].

Univariate and multivariate statistical methods are confronted as to their efficiency and objectivity. Similar to the comparison of patients showing chromosomal aberrations or serious diseases with their normal controls, the investigation of various populations can only result in the determination of differences on the basis of features arbitrarily selected, but not in a classification of systematic categories. Objections as to the objectivity of statistical procedures in the field of racial classification are discussed.

Anthropology↗
PubMed2003

[Impact of tumor size on long-term survival of patients with organ-confined renal cell cancer].

PURPOSE: As a result of the observation that the potential biological aggressiveness of even early stage renal cell cancer (RCC) strongly correlates with tumor size, the 5th edition of the TNM system (1997), which classifies all renal tumors up to a maximum diameter of 7 cm as T1, was modified in the current classification to distinguish T1a and T1b tumors based on a cut-off of 4 cm. Only a few larger investigations supporting this cut-off are available in the literature and these are based on univariate statistical analysis. To determine whether this cut-off best reflects the correlation between aggressive potential and tumor size and thus differentiates patients at low or high risk of progression, this investigation was performed using both univariate and multivariate statistical analysis. MATERIALS AND METHODS: Between 1981 and 2000, a total of 652 patients underwent tumor nephrectomy for renal cell carcinoma. Of these, the 243 patients with local RCC not extending beyond the renal capsule were subjected to univariate (log rank test) and multivariate (Cox regression model) statistical analysis. RESULTS: It became evident that, while during univariate analysis the prognostic calue of a cut-off size of 4 cm was confirmed, multivariate analysis identified the highest relative risk of cause-specific death (2.93) in those patients with tumors larger than 5 cm maximum diameter. CONCLUSIONS: The 5 cm cut-off thus appears to best determine the clinical prognosis for patients undergoing tumor nephrectomy for early stage renal call cancer. Taking this into consideration, the present study clearly demonstrates the reed for a multivariate statistical approach when the current modification of the TNM classification system is critically reevaluated.

Adult↗