Biomedical subjects

M Juhola

Publications and source records attributed to M Juhola.

At least 73 records · Page 4Linked to original sources

PubMed1998

Nonsteroidal anti-inflammatory drug-associated upper gastrointestinal lesions in rheumatoid arthritis patients. Relationships to gastric histology, Helicobacter pylori infection, and other risk factors for peptic ulcer.

BACKGROUND: Nonsteroidal anti-inflammatory drugs (NSAIDs) are risk factors for peptic ulcer in rheumatoid arthritis (RA) patients, but the contribution of reactive gastritis, concomitant Helicobacter pylori infection, or RA activity to NSAID ulcer pathogenesis is unknown. METHODS: Ninety-six RA patients taking NSAIDs and dyspeptic sex- and age-matched control patients without NSAID use or an RA diagnosis were enrolled in the study. RESULTS: Gastric ulcer (GU) was detected in 29 (30%) RA patients and 3 control patients (P < 0.001). Sixteen RA patients and no control patient had an H. pylori-negative GU. The GUs of the RA patients were mainly located in the prepyloric region (28%) and antrum (62%). Nine of the 29 RA patients (31%) with GU had more than 1 ulcer. Erosive gastropathy was detected in 34 (71% H. pylori-negative) RA patients and in 13 (62% H. pylori-negative) control subjects (P < 0.001). Chronic gastritis was observed in 65 RA patients (48% H. pylori-negative) and in 58 control subjects (43% H. pylori-negative) (NS). whereas reactive gastritis was found in only 2 RA patients and in none of the controls. Corticosteroid use was the only independent risk factor for GU: odds ratio was 6.8 (95% confidence interval, 1.3-36.0). The prevalences of duodenal ulcer or esophagitis were not increased in RA patients. CONCLUSIONS: RA patients using NSAIDs continuously are at a greatly increased risk of developing both H. pylori-negative and -positive GUs, and corticosteroid use is an independent risk factor for ulcer development. Most RA patients have chronic gastritis, whereas reactive gastritis is rarely associated with continuous NSAID use in RA patients.

Aged↗

PubMed1998

Comparison between diagnoses of human experts and a neurotologic expert system.

The decision-making ability of a recently developed neurotologic expert system was compared with the diagnoses of six physicians. Five of the physicians were residents and one was a specialist in the field of otolaryngology. The test patients were randomly selected from vertiginous patients referred to an otolaryngology clinic. The expert system and the physicians first had identical information on patient history, symptoms, and tests. During the second phase of the study the physicians were allowed to use the full medical records. The correct diagnoses were certified by an experienced specialist in neurotology. The expert system did better in decision-making when both the expert system and the physicians had identical information on patients. However, when the physicians were allowed to use patient's complete medical records, they surpassed the expert system. The expert system diagnosed 65% of the cases, while the physicians first diagnosed 54% of the cases, and then with complete information, 69% of the cases. From the patients' medical records, the physicians obtained information on the time perspective of the symptoms and the progression of the disease. These aspects will be used to further improve the expert system.

Adult↗

PubMed1998

Clinical significance of alpha-catenin, collagen IV, and Ki-67 expression in epithelial ovarian cancer.

PURPOSE: To analyze alpha-catenin and collagen IV expression in epithelial ovarian cancer with special reference to their prognostic significance and correlations with clinical and pathologic characteristics, as well as cell proliferation marker Ki-67. PATIENTS AND METHODS: Alpha-catenin, collagen IV, and Ki-67 expression was immunohistochemically analyzed in paraffin-embedded specimens of 316 patients with epithelial ovarian cancer. RESULTS: Alpha-catenin and collagen IV expression was not interrelated or related to International Federation of Gynecology and Obstetrics (FIGO) stage or proliferation marker Ki-67. Alpha-catenin expression was reduced (< 100%) in 50% of primary tumors. Reduced alpha-catenin and collagen IV expression was directly related to high histologic grade (P < .001). In both univariate and multivariate analyses, Ki-67 proliferation significantly predicted overall survival. In the subset of 86 patients with stage I tumor, a reduced (< 100%) alpha-catenin expression approached statistical significance as a negative prognostic factor (P = .035) and retained its statistical significance in the multivariate analysis (P = .025). The low (< 30%) expression of alpha-catenin (n = 10) was a sign of inferior survival as compared with normal expression in both the univariate (P = .0107) and multivariate analyses (P = .0105). CONCLUSION: Alpha-catenin expression seems to be a useful marker of those FIGO stage I tumors likely to run a less favorable course. The high cell proliferative activity was associated with poor survival. In the future, alpha-catenin and Ki-67 expression should be studied in a large prospective cohort that includes early-stage cancers to select the more aggressive tumors for intense early chemotherapy.

Adolescent↗

PubMed1998

Population size and quality in genetics-based rule learning from medical data.

Population size and quality are parameters which control the performance of genetic algorithms. We researched these parameters in a genetic-based machine learning system Galactica which was used to discover the differential diagnostic rules for female urinary incontinence from case data. The performance of the system was measured with on-line and off-line criteria. Surprisingly, randomly generated small populations (30 and 70 rules) did not promote the best on-line performance as earlier results suggested. Probable explanation is the lack of diversity in initial populations. The seeding of population with positive learning examples was used to obtain more divergent populations. As expected, the seeding increased the on-line performance of small populations. The results are mainly in accord with the earlier results indicating that large randomly generated populations (150 rules) lead to the better off-line performance. Again, the seeding of small populations was successful producing even the better off-line performance than a large population. In conclusion, the seeding allowed the small populations to converge to good rules in relatively short period of time.

Algorithms↗

PubMed1998

A signal analysis method for retinal image velocity computation of vestibular-ocular reflex eye movement investigations.

The vestibulo-ocular reflex preserves clear vision when the subject's head is moving rapidly. These eye movements are measured in order to investigate equilibrium diseases and disorders in otoneurology. The retinal image velocity is calculated to be a difference signal between the head movement velocity and the eye movement velocity. The eye movement position signal as well as the head movement position signal of the subject are concurrently measured when the subject is asked to move his head according to a stimulus and his gaze is fixated to a target. Eye movements are electro-oculographically recorded and head movements with a potentiometer. Tests performed to both patients of an equilibrium laboratory and normals exemplify that the method is applicable to indicate some otoneurological diseases.

Calibration↗

PubMed1998

Diagnosis of acute appendicitis in two databases. Evaluation of different neighborhoods with an LVQ neural network.

The use of an artificial neural network system was studied in the diagnosis of acute abdominal pain, especially acute appendicitis, with patients from Finland and Germany. Separate Learning Vector Quantization (LVQ) neural networks were trained with a training set from each database and also with a combined database. Each neural network was evaluated separately with a test set of cases from each database. With the combined database different neighborhood methods were compared to find the optimal choice for this decision-making problem. The acute appendicitis cases of the Finnish test data set were classified well with all the networks, but the cases of the German test set were difficult to classify for the Finnish network. The use of larger neighborhoods increased the sensitivity of the classification by nearly 10%. The differences in the results of the Finnish and German databases suggest that there are differences in the data collection or patient populations between centers. Therefore, care must be taken when using decision-support systems which have been developed in other centers. Neural networks offer a method to evaluate differences between databases. With the use of larger neighborhoods, the effects of the differences on the accuracy of the classification can be partly diminished.

Abdominal Pain↗

PubMed1997

Computational problems in the analysis of eye movement signals in the determination of vestibulo-ocular reflex.

The vestibulo-ocular reflex preserves clear vision when the head is moving fast. Measurement of the vestibulo-ocular reflex during the head autorotation test is usually calibrated using a dynamic technique in which the initial part of the eye movement signal and the corresponding part of the stimulating head movement signal are matched. Dynamic techniques can, however, be prone to generate excessively small or large calibration coefficients if a calibration segment of such a signal is corrupted by saccades or artifacts of large amplitudes. We have implemented an effective improvement for computation of difficult signals, not infrequent in clinical data, by limiting influence of distorting parts in the eye movement signal. We also discuss pitfalls of parameter accuracy concerning gain and phase parameters of the vestibulo-ocular reflex that are used to differentiate abnormal results from the normal. Furthermore, we call the ubiquituous Fast Fourier Transform method into question with regard to these signals.

Adult↗

PubMed1997

Latency estimation of auditory brainstem response by neural networks.

In the clinical application of auditory brainstem responses (ABRs), the latencies of five to seven main peaks are extremely important parameters for diagnosis. In practice, the latencies have mainly been done by manual measurement so far. In recent years, some new techniques have been developed involving automatic computer recognition. Computer recognition is difficult, however, since some peaks are complicated and vary a lot individually. In this paper, we introduce an artificial neural network method for ABR research. The detection of ABR is performed by using artificial neural networks. A proper bandpass filter is designed for peak extraction. Moreover, a new approach to estimate the latencies of the peaks by artificial neural networks is presented. The neural networks are studied in relation to the selection of model, number of layers and number of neurons in each hidden layer. Experimental results are described showing that artificial neural networks are a promising method in the study of ABR.

Evoked Potentials, Auditory, Brain Stem↗

PubMed1997

Pulmonary adiaspiromycosis in a two year old girl.

A case of disseminated bilateral pulmonary adiaspiromycosis is reported in a two year old Finnish girl. She recovered from this rare infection after treatment with amphotericin B. She is the first human case of adiaspiromycosis in Scandinavia and she is the youngest child with this disease reported so far. Electron microscopy showed that the three layers of the spore wall were not typical; rather, there seemed to be a gradual transition between the main wall zones, which may be split into an indefinite number of thin layers. Varying numbers and thicknesses were seen with different staining methods, and in different spores. Diagnosis relies on recognition of the fungus in a pulmonary biopsy specimen, because there are no reliable serological tests and culture of the fungus is time consuming and not always successful. It was thought that this patient had become infected as a result of contact with soil dust containing the spores in the yard surrounding her home, and as a result of her mother's work in a large garden shop.

Amphotericin B↗

PubMed1997

Vestibulo-ocular reflex function as measured with the head autorotation test.

The vestibulo-ocular reflex (VOR) of 125 healthy subjects was examined over the frequency range of 0.5-5 Hz with the head autorotation test (HART). During the HART the subjects fixated at a steady target while moving their heads horizontally from side to side with increasing frequencies according to auditory signals. The gain was determined as the ratio between the amplitude of the eye and head movements in five frequency bands between 0.5 and 5 Hz. The phase difference between the eye and head movements was determined in both degrees and milliseconds. The ability to reach high-frequency bands was evaluated. The mean gain was close to unity up 5 Hz, when it decreased to 0.91. The mean phase difference showed a lead of approximately 5 degrees at frequencies below 2 Hz, and at frequencies above 2 Hz there was no phase difference within the resolution of the test. The frequency band of 5 Hz was reached by 78% of the subjects, and that of 4 Hz was reached by 94% of the subjects. In summary, the HART is a new approach with which to study VOR function and determine accurately the VOR for healthy subjects. The normal upper frequency limit is 4 Hz in the HART.

Acoustic Stimulation↗

PubMed1997

Phase difference of vestibulo-ocular reflex in head autorotation test.

In the head autorotation test (HART) gain is commonly used to determine the vestibulo-ocular reflex (VOR). The purpose of this work was to evaluate the relevance of phase (the phase difference between the eye and corresponding head movement) in describing the VOR. The phase was determined in 5 frequency bands in both degrees and milliseconds (ms) in 4 groups: 30 healthy adults, 15 elderly subjects, 37 vestibular schwannoma (VS) patients, and 35 Meniere's disease (MD) patients. In healthy adults and in MD patients the phase was close to nil in the frequency bands of 3 and 4 Hz. In elderly subjects phase lead was between 5.0 and 15.5 ms in each frequency band. Patients with VS showed a phase lag of -4.2 to -7.6 ms. The mean phase of the elderly in the frequency band of 3 Hz differed statistically significantly from that of MD and VS patients, and in the frequency band of 4 Hz from that of healthy adults and VS patients. In summary, the elderly had phase lead and VS patients showed increased phase lag in the frequency bands higher than 2 Hz. The phase is useful parameter together with gain in evaluating VOR and it seems to change in aged subjects and in patients with permanent vestibular lesion.

Adult↗

PubMed1997

Changes in vestibulo-ocular reflex of elderly people.

Dizziness is a common symptom in elderly people. Head autorotation test (HART) has earlier shown no significant vestibulo-ocular reflex (VOR) disturbances in healthy elderly subjects. We used our recently developed HART to determine VOR in 14 elderly volunteers without otoneurological diseases and sedative medications. Gain and phase were determined in 5 frequency bands from 0.5 to 5 Hz. The gain of the elderly was significantly increased to 1.11-1.27 in the frequency range of 3-5 Hz compared with the controls. The phase lead of 7-8 degrees in the frequency bands of 2 and 4 Hz differed significantly from normative values of the controls. The percentage of the elderly to reach high-frequency head movements was diminished to 50% in the frequency band of 3 Hz and to 36% in the frequency band of 4 Hz (controls 100% and 95%, respectively). The individual HART results were abnormal in 86% of the elderly. The high-frequency VOR of the elderly was inaccurate in magnitude and timing. More than half of aged subjects were not able to generate voluntary fast head movements. These findings may explain the high prevalence of dizziness and falls in elderly subjects.

Accidental Falls↗

PubMed1997

Neural networks in neurotologic expert systems.

Artificial intelligence donates new possibilities to neurotologic research. Neural networks are a computer-based reasoning method which can be applied in expert systems created for clinical decision support. Neural networks have been used in medical imaging, in medical signal processing and to analyze both clinical and laboratory data. Principally, neural networks simulate the function of the brain. They have to be taught to make correct decisions from the input data. This learning process can be either supervised or unsupervised. The decision making is based on mathematical transformations and it occurs on a hidden level. Calculations are made on parallel manner and the decision making simulates pattern recognition method. Neural networks suit well in medical problems which cannot be defined in simple rules. A drawback of neural networks is that the decisions are irrational and cannot be motivated to the user. Another problem is neural networks' difficulty to handle incomplete input data, i.e., how to define some default or expected values for unknown input parameters. In a complex medical area, which would require multilayered neural networks, the neural networks require a large amount of solved cases for the learning process. In our experience neural networks seem not suitable for diagnosing vertigo and a better choice would be either case-based reasoning or possibly genetic algorithms or a combination of these.

Diagnosis, Computer-Assisted↗

PubMed1997

Peptic ulcer haemorrhage in Tartu County, Estonia: epidemiology and mortality risk factors.

BACKGROUND: The aim of the study was to assess the epidemiology and mortality risk factors of peptic ulcer haemorrhage (PUH) in Tartu County, Estonia. METHODS: In a prospective unselected defined area study, data for 144 patients aged > or = 15 years with new cases of PUH were analysed during a 2-year period. RESULTS: The incidence of PUH was 57 per 100,000 adult population per year, increasing from 12 in patients aged 20-29 years to more than 135 in those > or = 70 years. The incidence was 2.3-fold higher for men. The incidence of gastric ulcer haemorrhage was 26 (men, 33; women, 20) and that of duodenal ulcer 22 (men, 39; women, 9). Of the women 72% and of the men 37% were > or = 60 years. Nonsteroidal anti-inflammatory drugs (NSAIDs) were used by 45% of the patients (64% of women, 36% of men). Helicobacter pylori infection was present in 93% of the duodenal ulcer patients and in 81% of the gastric ulcer patients. Mortality (8%) was related to age, shock, haemoglobin < 80 g/l, cardiac comorbidity, and recurrence of haemorrhage. CONCLUSIONS: The incidence of PUH is relatively high owing to a high incidence among the younger population in Tartu County. Women with PUH are older, have consumed more NSAIDs, and have mainly gastric ulcer; men are younger, have consumed less NSAIDs, and are prone to duodenal ulcer haemorrhage. H. pylori infection is common in PUH patients. Mortality risk factors coincide with those reported by other researchers.

Adult↗

PubMed1997

Primary gastrointestinal non-Hodgkin's lymphoma. A population based study in central Finland in 1975-1993.

Gastrointestinal lymphomas have been uncommon, but the frequency of their predisposing conditions is increasing. The objective of the present study is to determine the frequency of gastrointestinal lymphomas in the area of central Finland as well as the influence of clinical features and therapeutical approaches on the survival of these patients. All samples of gastrointestinal non-Hodgkin's lymphomas diagnosed of patients living in the province of central Finland in 1975-1993 were re-examined. In central Finland the mean annual frequency of new gastrointestinal lymphomas was 10/1000000 in 1975-1984 and 16.0/1000000 in 1985-1993. The total incidence of gastrointestinal lymphomas in Finland adjusted for age to the world standard population was 12.5/1000000 in 1992. Two patients with peripheric T-cell lymphoma had a coeliac disease. Other predisposing conditions were not found. The stage of distribution of the lymphoma (p < 0.01) and radicality of the surgery (p < 0.01) were the most influencing factors on the survival of these patients. In conclusion the early distinction of gastrointestinal lymphomas is vital because of an increasing frequency of predisposing factors and a better prognosis due to new combination therapies.

Adolescent↗

PubMed1997

Parameter evaluation of the differential diagnosis of female urinary incontinence for the construction of an expert system.

Female urinary incontinence is a difficult problem for a patient but also for a physician. In the differential diagnosis of female urinary incontinence the physician has to determine a diagnostic class for the patient. This task is complex because of the unreliable patient history and the overlapping class boundaries. In order to develop an expert system to help the physician, a retrospective investigation on the incontinent women was performed to detect the potential expert system parameters. Also a diagnosis table was constructed from the expected values of parameters and the diagnostic classes. The results from K-means cluster analysis indicate that it is possible to develop the expert system on basis of the defined parameters and classes.

Adolescent↗

PubMed1996

Comparison of different neural network algorithms in the diagnosis of acute appendicitis.

Four different neural network algorithms, binary adaptive resonance theory (ART1), self-organizing map, learning vector quantization and back-propagation, were compared in the diagnosis of acute appendicitis with different parameter groups. The results show that supervised learning algorithms learning vector quantization and back-propagation were better than unsupervised algorithms in this medical decision making problem. The best results were obtained with the learning vector quantization. The self-organizing map algorithm showed good specificity, but this was in conjunction with lower sensitivity. The best parameter group was found to be the clinical signs. It seems beneficial to design a decision support system which uses these methods in the decision making process.

Adolescent↗

PubMed1996

Malthusian parameter on the Finnish population in the 20th century.

We were interested in studying a demographic indicator, the Malthusian parameter which had not been investigated earlier in the case of the Finnish population. We computed the Malthusian parameter with a known renewal equation, which is, as usual, approximated on discrete data by using normal distribution, on the Finnish population in the 20th century. The data was collected from the abundant official statistical sources which are known to be accurate and reliable in Finland. In addition to this parameter we computed the gross and net reproduction rates, the total fertility index, and the mean and variance age of females at child-bearing. The Malthusian parameter seems to be a rather good means of characterizing the development of the population. If the parameter is positive for long enough, the population tends to grow. If it is negative, as has been the case in Finland since 1969, the population starts to diminish sooner or later. On the other hand, it cannot take all factors into account. For instance, because of still increasing lifetime and also because of a relatively large quantity of females at the reproductive age the population is not yet decreasing in Finland. In any case, the Malthusian parameter forecasts the future trend of the decreasing population.

Adolescent↗