Biomedical subjects

M Juhola

Publications and source records attributed to M Juhola.

At least 55 records · Page 3Linked to original sources

PubMed1999

Predicting the development of a homogeneous population in an industrialized country.

The development of the Finnish population has been studied in order to predict its probable changes in the 21st century. More generally, the proposed iterative prediction procedure is useful for homogeneous populations in developed countries. The Finnish population is favorable for demographic studies because there exists accurate Finnish population data for a long historical period. Since several factors, for example natality, mortality, average female fertility and standard of living, have an impact on population, its modeling and prediction is an intricate matter. First, neural networks that are often efficient for nonlinear, complex systems were tried. However, it was found that there were far too many input parameters and a critical shortage of data to train and test neural networks. Instead, a straightforward, iterative procedure to predict the future development of the Finnish population was created, in particular giving its probable upper and lower limits.

Adolescent↗

PubMed1999

p21/WAF1 expression as related to p53, cell proliferation and prognosis in epithelial ovarian cancer.

The role and prognostic value of the tumour suppressor p21/WAF1 expression in epithelial ovarian cancer has not yet been defined. Therefore, the expression of p21/WAF1 was assessed immunohistochemically (IHC) in 316 epithelial ovarian malignancies in relation to p53, cell proliferation and patient survival. p21/WAF1 expression was inversely correlated with p53 and cell proliferation. Low p21/WAF1 expression was significantly associated with high grade of the tumour (P = 0.0005), advanced FIGO stage (P = 0.001) and primary residual tumour (P = 0.0001). Low p21/WAF1 expression was a marker of poor overall survival (P = 0.012). Similarly, p53-positivity and high cell proliferative activity were significant predictors of poor survival in univariate analyses. Moreover, the patients with p21-/p53+ tumours had a poorer overall (P < 0.00005) and recurrence-free (P = 0.0005) survival in univariate analyses, and the p21/p53 expression independently predicted tumour recurrence in Cox's multivariate analysis. Our results suggest that p21/WAF1 expression is mostly p53-dependent in epithelial ovarian cancer. High p21/WAF1 expression seems to function as a negative cell cycle regulator and as a marker of favourable disease outcome in epithelial ovarian cancer. In addition, the patients with their tumour expressing no or low p21/WAF1 protein but positive for p53 had a notably higher risk of recurrent disease, implicating that these patients might be more prone to treatment failures.

Carcinoma↗

PubMed1999

Otoneurological expert system for vertigo.

We have developed an otoneurological expert system (ONE) to aid the diagnostics of vertigo, to assist teaching and to implement a database for research. The ONE database is set to harvest data on patient history, signs and test results necessary for diagnostic work with vertiginous patients. A method based on pattern recognition was used in the reasoning process. Questions about symptoms, signs and test results are weighted and scored for each disease and the most likely disease is recognized from defined disease profiles. Missing information and uncertainties are solved with a method resembling fuzzy logic. ONE was validated by comparing diagnoses assessed by physicians with those provided by the system. It proved to be a valid decision-maker by solving 65% of the cases correctly, while the physicians' mean was 69%. To improve ONE further, a follow-up should be implemented for the patients, since diagnosing sudden deafness and Meniere's disease during the first visit is often impossible. We aim to obtain new information on diseases involving vertigo by applying adaptive computer applications, such as genetic algorithms, to the reasoning process.

Algorithms↗

PubMed1999

Chronic inflammation at the gastroesophageal junction (carditis) appears to be a specific finding related to Helicobacter pylori infection and gastroesophageal reflux disease. The Central Finland Endoscopy Study Group.

OBJECTIVE: The clinical significance of chronic inflammation at the gastroesophageal junction (carditis) is unknown: it may be associated with Helicobacter pylori (H. pylori) gastritis or with gastroesophageal reflux disease (GERD). We aimed to examine the association between carditis and H. pylori gastritis and endoscopic erosive esophagitis. METHODS: One thousand and fifty-three patients undergoing gastroscopy were enrolled in the study. Biopsy specimens were obtained from gastric antrum and corpus, immediately distal to normal-appearing squamocolumnar junction and distal esophagus. RESULTS: Chronic inflammation at the gastroesophageal junctional mucosa (carditis) was detected in 790 (75%) of 1053 patients. The male:female ratio of the carditis group was 1:1.5 and of the noncarditis group 1:1.6 (p = 0.6). The mean age of the carditis group was 58.7 yr (95% confidence interval [CI], 57.6-59.9) and of the noncarditis group, 52.6 yr (95% CI, 50.7-54.6, p < 0.001). Of the carditis group (N = 790), 549 (69%) had chronic gastritis (70% H. pylori positive) and 241 (31%) had normal gastric histology. In multivariate analyses, the only risk factor for carditis in subjects with chronic gastritis was H. pylori infection (odds ratio [OR], 2.9; 95% CI, 1.6-5.0), whereas the independent risk factor for carditis in subjects with histologically normal stomach was endoscopic erosive esophagitis (OR, 1.8; 95% CI, 1.1-3.1). The prevalence of complete intestinal metaplasia (IM) in the gastric cardia mucosa was 7% in the noncarditis group, 19% (p < 0.001) in the carditis group with chronic gastritis, and 10% (p = 0.3) in the carditis group with normal stomach. The respective prevalences of incomplete IM were 3%, 12% (p < 0.001), and 12% (p < 0.001). Among carditis patients with normal stomach histologically (N = 241), those with complete and/or incomplete IM (N = 49) were older than those with carditis only (63.6 yr [95% CI, 59.9-67.2] vs 51.4 yr [95% CI, 48.9-53.9]; p < 0.001). CONCLUSIONS: Two dissimilar types of chronic inflammation of the gastric cardia mucosa seem to occur, one existing in conjunction with chronic H. pylori gastritis and the other with normal stomach and erosive GERD. Most cases of chronic gastric cardia inflammation and intestinal metaplasia are detected in patients with chronic H. pylori gastritis.

Adult↗

PubMed1999

Specialized columnar epithelium of the esophagogastric junction: prevalence and associations. The Central Finland Endoscopy Study Group.

OBJECTIVES: In Barrett's esophagus (BE) normal squamous esophageal epithelium is replaced by specialized columnar epithelium (SCE). BE is related to gastroesophageal reflux disease (GERD) and is a risk factor for esophageal adenocarcinoma. SCE is detected also at normal-appearing esophagogastric junction without BE (junctional SCE). The relationships between junctional SCE, GERD, and cardia adenocarcinoma are obscure and controversial. The aims of the present study were to investigate the prevalence and demographics of junctional SCE and to compare these figures with those reported for BE, and esophageal and cardia adenocarcinoma. A further aim was to examine the association between junctional SCE and GERD, Helicobacter pylori infection, and gastritis. METHODS: One thousand one hundred-nineteen consecutive dyspeptic patients underwent gastroscopy and were enrolled into the study. RESULTS: Junctional SCE was detected in 110 patients (10%). The age-specific prevalence of junctional SCE increased with age. The male:female ratio was 1:1.1. In multivariate analysis, junctional SCE was independently and positively related to endoscopic erosive esophagitis (odds ratio [OR], 1.8; 95% confidence interval [CI], 1.1-3.1), cardia inflammation (carditis) (OR, 3.1; 95% CI, 1.4-6.8), and age (OR, 1.4 per decade; 95% CI, 1.2-1.6), but not to corpus H. pylori infection (OR, 1.4; 95% CI, 0.7-2.8), antral (OR, 1.0; 95% CI, 0.5-2.1) or corpus (OR, 0.8; 95% CI, 0.4-1.8) gastritis, or intestinal metaplasia of the antral mucosa in stomach (OR, 1.2; 95% CI, 0.7-2.1). In univariate analysis, junctional SCE was, however, significantly more common in patients with antral-predominant atrophic gastritis (20%), compared with those with normal gastric histology (8%, p < 0.001). CONCLUSIONS: Junctional SCE is age related and may therefore be an acquired lesion. It is associated with cardia inflammation and endoscopic erosive esophagitis, but not with H. pylori infection or gastric intestinal metaplasia. Unlike BE and cardia cancer, junctional SCE occurs with similar frequency in men and women.

Age Factors↗

PubMed1999

Complete and incomplete intestinal metaplasia at the oesophagogastric junction: prevalences and associations with endoscopic erosive oesophagitis and gastritis.

BACKGROUND/AIMS: Intestinal metaplasia (IM) is a common finding at the oesophagogastric junction, but the aetiopathogenesis of the different IM subtypes-that is, incomplete IM (specialised columnar epithelium, SCE) and complete IM- and their associations with gastro-oesophageal reflux disease and Helicobacter pylori gastritis are unclear. METHODS: 1058 consecutive dyspeptic patients undergoing gastroscopy were enrolled. The gastric, oesophagogastric junctional, and oesophageal biopsy specimens obtained were stained with haematoxylin and eosin, alcian blue (pH 2.5)-periodic acid Schiff, and modified Giemsa. RESULTS: Complete junctional IM was detected in 196 (19%) of the 1058 subjects, and in 134 (13%) was the sole IM subtype. Incomplete junctional IM (SCE) was detected in 101 (10%) subjects, of whom 62 (61%) also had the complete IM subtype. Of patients with normal gastric histology (n = 426), 6% had complete IM and 7% junctional SCE. The prevalence of both types of IM increased with age in patients with either normal gastric histology or chronic gastritis (n = 611). Epithelial dysplasia was not detected in any patients with junctional IM. In multivariate analysis, independent risk factors for incomplete junctional IM were age (odds ratio (OR) 1.3 per decade, 95% confidence interval (CI) 1.2 to 1.6), endoscopic erosive oesophagitis (OR 1.9, 95% CI 1.1 to 3.2), and chronic cardia inflammation (OR 2.9, 95% CI 1.3 to 6.2), but not gastric H pylori infection (OR 1.0, 95% CI 0.6 to 1.7). In univariate analysis, junctional incomplete IM was not associated with cardia H pylori infection. Independent risk factors for "pure" complete junctional IM (n = 134) were age (OR 1.2 per decade, 95% CI 1.0 to 1.4), antral predominant non-atrophic gastritis (OR 2.6, 95% CI 1.3 to 5.2), antral predominant atrophic gastritis (OR 2.1, 95% CI 1.1 to 5.2), and multifocal atrophic gastritis (OR 7.1, 95% CI 2.5 to 19.8). In univariate analysis, junctional complete IM was strongly associated with chronic cardia inflammation and cardia H pylori infection (p<0. 001). CONCLUSIONS: Both complete and incomplete junctional IM are independent acquired lesions that increase in prevalence with age. Although IM subtypes often occur simultaneously, they show remarkable differences in their associations with gastritis and erosive oesophagitis: junctional complete IM is a manifestation of multifocal atrophic gastritis, while the incomplete form (SCE) may result from carditis and gastro-oesophageal reflux disease. The frequency of dysplasia in intestinal metaplasia at the oesophagogastric junction appears to be low.

Aged↗

PubMed1999

Discovering diagnostic rules from a neurotologic database with genetic algorithms.

Data on patients with Meniere's disease, vestibular schwannoma, traumatic vertigo, sudden deafness, benign paroxysmal positional vertigo, or vestibular neuritis were retrieved from the database of otoneurologic expert system ONE for the development and testing of a genetic algorithm (GA). The accuracy of the diagnostic rules in solving the test cases was 81%, 91%, 92%, 95%, 96%, and 98% for the respective diseases. The best rules retrieved from the GA were described by a set of questions with the most likely answers. The most important questions concerned the duration of hearing loss and the occurrence of head injury. The validity and structure of the rules created with a GA can be analyzed in detail. For rare diseases, some other reasoning process can be used, for example, case-based reasoning.

Algorithms↗

PubMed1999

Comparison of two head autorotation tests.

The head autorotation test is a novel method for studying the high-frequency vestibuloocular reflex without heavy machinery to generate whole-body rotation. Despite many studies with the test, the method is far from standardized, and no comparison has been made of different versions of the test. The objective of this study was to compare the vestibuloocular reflex of 100 healthy subjects measured simultaneously with two versions of the head autorotation test. Gain, phase, asymmetry, and the frequency bands reached were determined in the frequency bands of 1, 2, 3, 4, and 5 Hz. The gain measured with both tests was close to unity (range 0.95-1.04) from 1 to 4 Hz and about 0.9 at 5 Hz. In the test developed by Vorteq the phase lagged (-7 to -21 degrees) in all the frequency bands, and it differed significantly from the phase lead of 2 to 5 degrees that was measured by the other test. The asymmetry measured with the Vorteq test increased continuously from 1.5% (1 Hz) to 5.7% (5 Hz). The results of the tests showed intersubject variation, which was larger in the higher frequency bands. In conclusion, the high-frequency vestibuloocular reflex of healthy subjects can be quantified with active head oscillation. Both tests produced similar gain results, but the phase results differed systematically. Thus, the results of different head autorotation tests may not be directly comparable.

Adult↗

PubMed1999

Comparison of genetic algorithms and other classification methods in the diagnosis of female urinary incontinence.

Galactica, a newly developed machine-learning system that utilizes a genetic algorithm for learning, was compared with discriminant analysis, logistic regression, k-means cluster analysis, a C4.5 decision-tree generator and a random bit climber hill-climbing algorithm. The methods were evaluated in the diagnosis of female urinary incontinence in terms of prediction accuracy of classifiers, on the basis of patient data. The best methods were discriminant analysis, logistic regression, C4.5 and Galactica. Practically no statistically significant differences existed between the prediction accuracy of these classification methods. We consider that machine-learning systems C4.5 and Galactica are preferable for automatic construction of medical decision aids, because they can cope with missing data values directly and can present a classifier in a comprehensible form. Galactica performed nearly as well as C4.5. The results are in agreement with the results of earlier research, indicating that genetic algorithms are a competitive method for constructing classifiers from medical data.

Algorithms↗

PubMed1999

Three-dimensional ROIs in brain PET.

A semi-automatic system for determining volumes of interest (VOI) from positron emission tomography (PET) scans of brain is described. The VOIs surface extraction is based on user selectable threshold and three-dimensional target flood-fill. Contrast to anatomical volume detection approaches, volumes are determined from functional PET images and the obtained objects are checked against anatomical images. The developed VOI program was evaluated with brain FDOPA-PET studies where the striatum was the object. The results were comparable to entirely manual method and the target extraction time is reduced to about one third of manual method.

Algorithms↗

PubMed1999

A signal analysis method for impulse-like eye movements.

Eye movement investigations are performed in several fields of medicine. We have developed signal analysis methods of eye movements studied in otoneurology for several years. Previously, we have designed methods for eye movement types of saccades, nystagmus, smooth pursuit, and vestibulo-ocular reflex. In this paper we extend and develop further our method to concern also impulse-like eye movements, i.e. a new type of eye movement tests for investigations of vertiginous patients. According to our preliminary results the use of our method is efficient to differentiate patients with inner ear diseases from normals.

Diagnosis, Computer-Assisted↗

PubMed1999

Lossless compression of eye movement signals.

Compression of digital signals is widely employed in several areas such as speech signals. Concerning biomedical signals almost merely ECG signals have so far been compressed, in fact, in very many applications. To our knowledge, this compression study is the first one presented in the case of eye movement signal which are investigated in several medical specialties. In this study eye movements are electro-oculographically recorded. Tests performed to signals of patients of an equilibrium laboratory gave compression ratios generated with essential lossless compression methods.

Electronystagmography↗

PubMed1999

Treatment of missing values with imputation for the analysis of otologic data.

Usefulness of imputation in the treatment of missing values in an otologic database was studied. Missing values were filled in with means (ME), regression (LR) and Expectation-Maximization (EM) imputation methods. A random imputation method (RA) provided baseline results. ME, LR and EM methods agreed on 41-42% of the imputed missing values. The level of agreement between these and RA method was 20-22%. Despite the moderate agreement, discriminant functions were similar and accurate (prediction accuracy 83-99%) for each diagnosis. A lot of data were missing in otoneurotologic tests which have less weight in the diagnosis of vertiginous patients. Consequently, the disagreement of the methods did not affect discriminant analysis. Inputation seems to be a useful method to treat missing data in this database, but future research requires more complete data and advanced imputation methods.

Data Collection↗

PubMed1999

Modelling oculomotor data with decision tree induction.

We studied relationships between oculomotor test results and the site of lesion in the data set containing patient cases with operated cerebello-pontine angle tumour, operated hemangioblastoma, infarction of cerebello-brainstem or Meniere's disease and control subjects. Several classification models were generated by decision tree induction to find parameter combinations which are efficient in classification. The studied data were characterised by missing values and scarcity of example cases. This study suggested that decision tree induction can be a useful method even in problematic real world classification tasks. Models generated by decision tree induction and evaluated by an expert physician may give information that is beneficial for research.

Brain Stem Infarctions↗

PubMed1998

Cytoplasmic accumulation of alpha-catenin is associated with aggressive features in laryngeal squamous-cell carcinoma.

Aberrations in the function of alpha-catenin (alpha-cat), the anchoring protein of E-cadherin, are believed to cause dysfunction of the cadherin-catenin complex, leading to disturbed cell-cell adhesion. It has been suggested that expression of alpha-cat in human tumours might be a better indicator of aggressive phenotype than expression of E-cadherin. The value of alpha-cat as a prognostic marker in laryngeal squamous cell carcinoma (LSCC) is unclear. To determine the potential prognostic significance of alpha-cat, paraffin-embedded samples from 159 patients with invasive carcinoma left in the section and with long-term follow-up were evaluated immuno-histochemically for alpha-cat expression, and the results were related to histopathological grade, tumour stage and survival. Two patterns of staining were observed: pure membranous staining (57%) and membranous staining with cytoplasmic involvement (43%). Cytoplasmic involvement of alpha-cat was associated with dedifferentiation, advanced tumour stage and nodal status. In addition, supra-glottic tumours showed more often cytoplasmic involvement of alpha-cat than glottic tumours. Patients with cytoplasmic involvement appeared to have a trend towards poor overall survival, though without statistical significance. These results suggest that cytoplasmic involvement of alpha-cat is associated with aggressive behaviour and metastatic phenotype of LSCC.

Adult↗

PubMed1998

A genetic-based machine learning system to discover the diagnostic rules for female urinary incontinence.

A machine learning system named Galactica has been developed which uses a genetic algorithm to discover the rules for an expert system from databases. Galactica devised accurate diagnostic rules for female urinary incontinence from difficult heterogeneous data. The percentages of correctly classified stress, mixed and sensory urge incontinence testing cases were 89, 86 and 87%, respectively. However, these rules were rather general, consisting of 4-6 out of 13 conditions available in the data. Diagnostic rules for stress and mixed incontinence extracted from straightforward homogeneous data were highly accurate, classifying 100% of testing cases correctly as well as being specific, having from 10 to 11 conditions. More specific, but less accurate, rules were found from heterogeneous data with a biased fitness function. All of the rules were correct, i.e. every condition in the rules had the expected value specified by the expert. Although, Galactica achieved a slightly better classification than the discriminant analysis, it is argued that the genetic approach is better than the statistical one, due to symbolic rules being comprehensible, whereas understanding a complex mathematical model requires statistical expertise.

Algorithms↗

PubMed1998

Treatment of missing data values in a neural network based decision support system for acute abdominal pain.

In this study different substitution methods for the replacement of missing data values were inspected for the use of these cases in a neural network based decision support system for acute appendicitis. The leucocyte count had the greatest number of missing values and was used in the analyses. Four different methods were compared: substituting means, random values, nearest neighbour and a neural network. There were great differences in the substituted leucocyte count values between different methods and only nearest neighbour and neural network agreed about most of the cases. The importance of the substitution method for the final diagnostic classification of the patients by the neural network based decision support system was found to be small.

Abdominal Pain↗

PubMed1998

Changes in the vestibulo-ocular reflex: a study of elderly day hospital patients.

The vestibulo-ocular reflex (VOR) of 50 elderly day hospital patients (mean age of 82 years) was studied with the head autorotation test. Amplitude gain, phase and the highest frequency band reached were determined in the five frequency bands of 1, 2, 3, 4, and 5 Hz. Of the 50 patients, 81% had abnormal results. The gain of the elderly was significantly increased to 1.06-1.24 in the frequency bands of 3, 4, and 5 Hz in comparison with that of a control group. The elderly showed constantly a phase lead of 8-19 degrees in the frequency range of 1-4 hz and in this range differed significantly from the control group. The percentage of the elderly who reached high frequencies of head movements was reduced to 55% in the frequency band of 3 Hz and to 30% in the frequency band of 4 Hz. These findings may lead to oscillopsia and explain the high prevalence of dizziness and falls among the elderly.

Accidental Falls↗