Application of a modified two-point backward difference to sequential event detection in surface electromyography.

Reliable detection of onset and termination of muscle contraction is an essential task in the analysis of surface electromyographic signals. An event detection method that can be used for sequential detection of both onset and termination of muscle contraction is described. The method builds on the techniques of envelope detection, two-point backward difference and threshold based decision making. Therefore, fast conventional digital signal processing techniques can be used in its implementation. Because the method is computationally efficient, it can be employed in both real-time and non-real-time applications. This text discusses the architecture of the method, considers the practical aspects of its implementation, analyses its computational complexity and evaluates its performance on the grounds of experimental results.

Modelling stabilograms with hidden Markov models.

Hidden Markov models are an effective computational method for modelling and interpreting digital signals of biological, as well as other, origin. In the current investigation, we explored whether hidden Markov models can be used to control and represent phenomena in human balance signals recorded from subjects standing on a force platform. Additionally, our aim was to classify healthy controls and patients who suffered from Meniere's disease into their own classes. Hidden Markov models were capable of these tasks and of overcoming such disturbances as noise and other unforeseen perturbations in balance signals, which are inherently complex and possibly difficult to visually specify.

Differential cancer predisposition in Lynch syndrome: insights from molecular analysis of brain and urinary tract tumors.

Hereditary non-polyposis colorectal carcinoma (Lynch syndrome) is among the most common hereditary cancers in man and a model of cancers arising through deficient DNA mismatch repair (MMR). Lynch syndrome patients are predisposed to different cancers in a non-random fashion, the basis of which is poorly understood. We addressed this issue by determining the molecular profiles for different tumors from a nationwide cohort of Lynch syndrome families (approximately 150 tumors in total). We focused on some less prevalent cancers, affecting the brain (n = 7) and urinary tract (five bladder and five ureter uroepithelial cancers and four kidney adenocarcinomas), and compared their molecular characteristics to those of the most common cancers, colorectal, gastric and endometrial adenocarcinomas, from the same families. Despite origin from verified MMR gene mutation carriers, the frequency of high-level microsatellite instability in tumors varied between high (100-96% for ureter, stomach and colon), intermediate (63-60% for endometrium and bladder) and low (25-0% for kidney and brain). In contrast to gastrointestinal and endometrial carcinomas, active (nuclear) beta-catenin was rare and KRAS mutations were absent in brain and urological tumors. Compared with other tumors, frequent stabilization of p53 protein characterized urinary tract cancers. Promoter methylation of tumor suppressor genes discriminated the tumors in an organ-specific manner. Our findings suggest that different Lynch syndrome tumors develop along different routes. Uroepithelial cancers of the ureter (and bladder to lesser extent) share many characteristics of MMR deficiency-driven tumorigenesis, whereas brain tumors and kidney adenocarcinomas follow separate pathways.

Is gastric cancer part of the tumour spectrum of hereditary non-polyposis colorectal cancer? A molecular genetic study.

BACKGROUND: Gastric cancer is the second most common extracolonic malignancy in individuals with hereditary non-polyposis colorectal cancer (HNPCC)/Lynch syndrome. As gastric cancer is relatively common in the general population as well, it is not clear whether or not gastric cancer is a true HNPCC spectrum malignancy. AIM: To determine whether or not gastric cancer is a true HNPCC spectrum malignancy. SUBJECTS AND METHODS: The molecular and clinicopathological profiles of gastric cancers (n = 13) from HNPCC mutation carriers were evaluated and compared with the profiles of sporadic gastric cancers (n = 46) stratified by histology and microsatellite instability (MSI) status. RESULTS: This study on sporadic and HNPCC gastric cancers revealed several important universal associations. Loss of heterozygosity in the adenomatous polyposis coli (APC) region was associated with intestinal histology regardless of the MSI (p = 0.007). KRAS-mutations (p = 0.019) and frameshift mutations in repeat tracts of growth-regulatory genes (p<0.001) were associated with MSI tumours being absent in microsatellite stable (MSS) tumours. The average number of methylated tumour suppressor gene loci among the 24 genes studied (methylation index) was higher in MSI than in MSS tumours regardless of histology (p<0.001). Gastric cancers from HNPCC mutation carriers resembled sporadic intestinal MSI gastric cancers, except that MLH1 promoter methylation was absent (p<0.001) and the general methylation index was lower (p = 0.038), suggesting similar, but not identical, developmental pathways. All these lacked the mismatch repair protein corresponding to the germline mutation and displayed high MSI. CONCLUSION: The present molecular evidence, combined with the previous demonstration of an increased incidence relative to the general population, justify considering gastric cancers as true HNPCC spectrum malignancies.

CD44 expression and its relationship with MMP-9, clinicopathological factors and survival in oral squamous cell carcinoma.

We investigated the expression of CD44 and MMP-9 in primary oral squamous cell carcinoma (OSCC) and evaluated their association with each other and clinicopathological factors as well as their prognostic value during long term follow up. Histological samples from 138 OSCC patients were immunohistochemically stained for the expression of CD44 and MMP-9. The staining results were compared with conventional prognostic factors and their impacts to patients' prognosis were also studied with survival analyses. Irregular staining of CD44 in tumour cells was associated with poor tumour differentiation (p=0.003), higher clinical stage (III-IV) (p=0.049), and the presence of T3-4 tumour stage (p=0.03). Strong stromal MMP-9 staining intensity was correlated with poor tumour differentiation (p=0.03). In univariate survival analysis irregular staining of CD44 in tumour cells was related to poor disease free and overall survival (p=0.001 and p<0.001, respectively). In multivariate analysis CD44 staining was a significant independent predictor for overall (p=0.03) and disease free survival (p=0.003). MMP-9 expression showed no statistical significance in survival analyses. Strong stromal staining intensity of MMP-9 correlated with irregular staining of CD44 in tumour cells, but had no prognostic significance in the present cohort. However, irregular staining of CD44 predicted more advanced disease and shortened survival of the patients.

Prognostic significance of E-cadherin-catenin complex in epithelial ovarian cancer.

OBJECTIVE: To clarify the prognostic role of E-cadherin and beta- and gamma-catenins, and their relation to CD44 in epithelial ovarian carcinoma. METHODS: The expression of E-cadherin and beta- and gamma-catenins was analysed immunohistochemically in 305 primary epithelial ovarian cancers and 44 metastases, and related to CD44 expression, clinicopathological factors, and the patients' survival. RESULTS: Reduced cell surface expression of E-cadherin, beta-catenin, and gamma-catenin was particularly frequent in serous and endometrioid histological types. Reduced cell surface expression of E-cadherin and beta-catenin was also associated with poor differentiation. Nuclear positivity of beta-catenin was associated with high CD44 expression, endometrioid histology, and local stage of the tumour, whereas nuclear gamma-catenin expression was associated with serous histology and poor differentiation. In the univariate analysis, preserved cell surface beta-catenin expression in the whole study material and nuclear expression of beta- and gamma-catenins in the subgroup of endometrioid ovarian cancers were predictors of better 10 year disease related survival. Preserved cell surface expression of E-cadherin and beta-catenin predicted favourable recurrence-free survival. These statistical significances were not retained in multivariate analysis. CONCLUSIONS: The correlation between nuclear beta-catenin and CD44 indicates that beta-catenin may regulate the transcription of CD44 in epithelial ovarian cancer. E-cadherin-catenin complex members are associated with the prognosis of patients with epithelial ovarian cancer, but these univariate associations were not strong enough to compete for significance with the traditional clinicopathological factors.

The changing epidemiology of esophageal cancer in Finland and the impact of the surveillance of Barrett's esophagus in detecting esophageal adenocarcinoma.

We examined the epidemiology of esophageal cancer in Finland and the role of the surveillance of Barrett's esophagus (BE) in detecting esophageal adenocarcinoma (EA) in our own hospital referral area. We observed that the incidence of EA in men has increased tenfold from the 1970s and was 1.10/100,000/year in 1998-2002. In women, a 4.5-fold increase was observed (incidence 0.11/100,000/year). In 1998-2002, the mean annual number of new EA cases was 57.4 (79.8% men) in Finland with a population of 5.2 million. In our hospital referral area with a mean population of 261 349, 11 EAs were observed in 1996-2001. Of them, two (18.2%) had BE. One EA was detected during surveillance. EA comprised 0.05% of all causes of deaths in our hospital referral area. We conclude that EA incidence has increased significantly in men in Finland, but still EA is seldom detected on BE surveillance. EA is an uncommon cause of death in our hospital referral area.

Is it possible to reduce endoscopy workload using age, alarm symptoms and H. pylori as predictors of peptic ulcer and oesophagogastric cancers?

OBJECTIVES: We examined referrals to oesophagogastroduodenoscopy and the impact of demographic and clinical variables to predict major findings (peptic ulcer, cancer) on oesophagogastroduodenoscopy. METHODS: We collected data on 3669 consecutive patients referred for oesophagogastroduodenoscopy. RESULTS: Dyspeptic and reflux symptoms constituted 80% of oesophagogastroduodenoscopy referrals. A major finding was observed in 419 patients (11.4%). The mean age of cancer patients was 72.7 years (95% confidence interval (CI) 70.0-76.5 years) and that of peptic ulcer patients 62.0 years (95% CI 60.5-63.5 years). Independent risk factors for a major finding were age >50 years (odds ratio (OR) 1.62, 95% CI 1.24-2.10), male sex (OR 1.38, 95% CI 1.11-1.72), ulcer-type pain (OR 2.33, 95% CI 1.80-3.02), weight loss (OR 1.70, 95% CI 1.14-2.53), anaemia (OR 1.82, 95% CI 1.38-2.40), bleeding symptoms (OR 3.27, 95% CI 2.26-4.75) and Helicobacter pylori (OR 2.49, 95% CI 2.00-3.11), whereas reflux symptoms were protective (OR 0.73, 95% CI 0.53-1.00). The area under receiver operating characteristic curve of age over 50 years with alarm symptoms to predict major finding was 0.68 (95% CI 0.65-0.71), which positive H. pylori status increased to 0.71 (95% CI 0.69-0.74). Of the major findings, 87.2% were detected in patients with risk factors. Major findings were detected in 15.1% patients with and 8.1% (p < 0.001) without alarm symptoms. CONCLUSIONS: Dyspeptic and reflux symptoms constitute the majority of oesophagogastroduodenoscopy workload. Discriminative power of alarm symptoms even with positive H. pylori status to detect peptic ulcer or cancer was low. Because of their low cancer risk, reflux and dyspeptic patients younger than 50 years can be treated without oesophagogastroduodenoscopy.

Systematic segregation to mutant mitochondrial DNA and accompanying loss of mitochondrial DNA in human NT2 teratocarcinoma Cybrids.

In this study a well-characterized pathological mutation at nucleotide position 3243 of human mitochondrial DNA was introduced into human rho(0) teratocarcinoma (NT2) cells. In cloned and mixed populations of NT2 cells heteroplasmic for the mutation, mitotic segregation toward increasing levels of mutant mitochondrial DNA always occurred. Rapid segregation was frequently followed by complete loss of mitochondrial DNA. These findings support the idea that pathological mitochondrial DNA mutations are particularly deleterious in specific cell types, which can explain some of the tissue-specific aspects of mitochondrial DNA diseases. Moreover, these findings suggest that mitochondrial DNA depletion may be an important and widespread feature of mitochondrial DNA disease.

Gene expression signatures for colorectal cancer microsatellite status and HNPCC.

The majority of microsatellite instable (MSI) colorectal cancers are sporadic, but a subset belongs to the syndrome hereditary non-polyposis colorectal cancer (HNPCC). Microsatellite instability is caused by dysfunction of the mismatch repair (MMR) system that leads to a mutator phenotype, and MSI is correlated to prognosis and response to chemotherapy. Gene expression signatures as predictive markers are being developed for many cancers, and the identification of a signature for MMR deficiency would be of interest both clinically and biologically. To address this issue, we profiled the gene expression of 101 stage II and III colorectal cancers (34 MSI, 67 microsatellite stable (MSS)) using high-density oligonucleotide microarrays. From these data, we constructed a nine-gene signature capable of separating the mismatch repair proficient and deficient tumours. Subsequently, we demonstrated the robustness of the signature by transferring it to a real-time RT-PCR platform. Using this platform, the signature was validated on an independent test set consisting of 47 tumours (10 MSI, 37 MSS), of which 45 were correctly classified. In a second step, we constructed a signature capable of separating MMR-deficient tumours into sporadic MSI and HNPCC cases, and validated this by a mathematical cross-validation approach. The demonstration that this two-step classification approach can identify MSI as well as HNPCC cases merits further gene expression studies to identify prognostic signatures.

Tumour regression grading in the evaluation of tumour response after different preoperative radiotherapy treatments for rectal carcinoma.

BACKGROUND AND AIMS: Preoperative radiotherapy (PRT) for rectal carcinoma has been shown to cause tumour regression and increase local control and patient survival. The aim of this study was to examine the usefulness of tumour regression grading (TRG) in quantifying the effect of PRT. METHODS: Depending on the tumour stage (uT), as defined by preoperative endorectal ultrasound (ERUS), fixity and distance from the anal verge, 126 patients with rectal cancer underwent either surgery alone, or received short-course 25-Gy radiotherapy or long-course 50-Gy radiotherapy combined with 5-fluorouracil (5-FU) before surgery. TRG in each group was assessed and compared with the downstaging, defined as a change in preoperative uT stage and pathologic stage (pT). RESULTS: Complete response (no residual tumour, TRG 1) was seen in 7% of the patients (3/44) and total or major regression (TRG 1-3) in 73% of the patients (32/44) treated with 50-Gy chemoradiation. Of those treated with 25-Gy PRT, 21% (9/42) showed major tumour regression. Of the patients who underwent ERUS and PRT, 32% (26/83) were downstaged when comparing uT with pT, but 53% (14/26) of the downstaged tumours showed no response by TRG. In comparison, 50% (28/57) of the tumours with no downstaging showed a marked response by TRG (p=0.05). CONCLUSIONS: Tumour regression grading offers detailed information of the effect of PRT and shows that tumour regression is more marked after long-term chemoradiation than after short-course radiotherapy (p=0.02). In contrast, T-stage downstaging was similar in both groups and did not correlate with the TRG results (p=0.05).

Gastric metaplasia and chronic inflammation at the duodenal bulb mucosa.

BACKGROUND: Chronic inflammation and gastric metaplasia are often observed in biopsy specimens from the duodenal bulb of Heliobacter pylori positive patients with duodenal ulcer disease (DU). AIMS: We set out to investigate the prevalence of these lesions and their associations with other gastric and duodenal histopathological lesions. PATIENTS: A total of 1255 consecutive patients who underwent upper gastrointestinal endoscopy were recruited into the present study. METHODS: Two biopsy specimens were obtained from each of the following sites: duodenal bulb, gastric antrum, gastric body, and distal to the superior duodenal angle. These specimens were stained with hematoxylin-eosin, alcian blue periodic acid Schiff (pH 2.5) and modified Giemsa (Heliobacter pylori infection was determined only by histology). RESULTS: The mean age of the study population was 57 years, and male:female ratio 1:1.6. Overall, 235 (19%) had gastric metaplasia and/or chronic inflammation in the duodenal bulb mucosa, and H. pylori organisms could be found in 17 (1%). In univariate analyses, gastric metaplasia and/or chronic duodenal bulb inflammation positively associated with male sex (p = 0.046), Heliobacter pylori-positive chronic gastritis (p = 0.033), villous atrophy of distal duodenal mucosa, i.e., coeliac disease (p < 0.001), duodenal ulcer (p < 0.001), and duodenal bulb deformity and scarring in endoscopy (p < 0.001), but not with age (p = 0.7) nor use of nonsteroidal anti-inflammatory drugs (p = 0.055). Multivariate analysis revealed that independent risk factors for gastric metaplasia and chronic inflammation in duodenal bulb were duodenal Heliobacter pylori infection (odds ratio 1.6, 95% confidence interval CI 1.1-2.1), and villous atrophy of the distal duodenal mucosa (odds ratio 12.7, 95% CI 4.4-36.5), while chronic atrophic gastritis was protective against them (odds ratio 0.5, 95% CI 0.3-0.8). CONCLUSIONS: In addition to Heliobacter pylori infection, duodenal bulb gastric metaplasia and chronic inflammation may result from predisposition to toxic dietary components in gluten-sensitive subjects.

Impact of clinical symptoms and referral volume on endoscopy for detecting peptic ulcer and gastric neoplasms.

BACKGROUND: We investigated the volume of dyspeptic patients referred by general practitioners (GPs) to upper gastrointestinal endoscopy and the impact on endoscopic findings. We also examined the correlation between clinical symptoms and endoscopic findings. METHODS: We collected data on patients sent for upper gastrointestinal endoscopy by GPs of 30 healthcare centres in 1996 in our hospital referral area of 260,000 inhabitants. In addition, national and local cancer registries were used to enumerate the gastric cancer cases detected in 1996. RESULTS: The study population consisted of 3378 patients, mean age 58 years (interquartile range 25 years, male:female 1:1.3). Among the 30 healthcare centres, referral volumes for upper gastrointestinal endoscopy varied from 0.6 to 9.2 per 1000 inhabitants per year (median 3.3/1000/year). In healthcare units with 'high' (> or = 3.3/1000/year, 15 healthcare units, 1297 patients) and 'low' (<3.3/1000/year, 15 healthcare units, 2065 patients) referral volumes, the detection rates were as follows: duodenal ulcer (DU) 3.5% (n = 46) versus 4.0% (n = 83, P = 0.5), gastric ulcer (GU) 4.9% (n = 64) versus 5.3% (n = 110, P = 0.6), gastropathy 43.8% (n = 568) versus 35.6% (n = 736, P < 0.001), gastric cancer 0.5% (n = 6) versus 0.5% (n = 11, P = 0.8), gastric polyps 2.4% (n = 31) versus 1.5% (n = 30, P < 0.05). Independent risk factors for gastric cancer were age (OR 6.5 per decade, 95% CI 2.4-17.9), male sex (OR 5.5, 95% CI 1.8-17.1) and alarming symptoms and/or signs (OR 3.6, 95% CI 1.2-10.7); for GU, Helicobacter pylori (OR 2.6, 95% CI 1.9-3.5) and alarming symptoms (OR 2.0, 95% CI 1.4-2.7); for DU, male sex (OR 1.6, 95% CI 1.1-2.2) and H. pylori (OR 3.9, 95% CI 2.7-5.5); and for gastric polyp(s), age (OR 2.0 per decade, 95% CI 1.1-3.5) and high referral volume (OR 1.7, 95% CI 1.0-2.0). A high referral volume did not associate positively either with the number of peptic ulcers or gastric cancer. CONCLUSIONS: Alarm symptoms associate strongly with significant gastric lesions such as GU and cancer. Increased referral volume results in an increased number of gastropathy and gastric polyp(s), but not of peptic ulcer or cancer.

Motorized head impulse stimulator to determine angular horizontal vestibulo-ocular reflex.

The objective of the current study was to develop a computer-controlled mechanical system for the generation of impulsive head rotations to measure eye movements induced by angular horizontal vestibulo-ocular reflex. This is a clinical eye movement test recently introduced for the usage of otoneurological balance laboratories. We built the system and modified our prior computer software developed for other types of eye movement tests. Motor controlled stimulation has fulfilled the requirement of more uniform and constant acceleration stimulation than obtained with manually administrated impulses. After having executed preliminary experiments at our balance laboratory we found the system to be efficient, reliable and secure.

Immunohistochemical study of neuroendocrine cells at the gastric cardia mucosa.

BACKGROUND/AIMS: The gastric cardia mucosa is a narrow band of tissue between the oesophagus and the stomach. The physiological role of this tissue is unknown. This study examined the presence and characteristics of neuroendocrine cells at this site. METHODS: Biopsy samples were obtained from across normal appearing squamocolumnar junctions. The cardiac mucosa was defined as the presence of special type mucosa composed of mucous secreting glands in the immediate vicinity of oesophageal squamous epithelium. Biopsy specimens were stained with haematoxylin and eosin, alcian blue (pH 2.5) periodic acid Schiff, and modified Giemsa. The chromogranin A and Fontana-Masson stains were used to identify neuroendocrine cells, which were also stained immunohistochemically for gastrin, serotonin, glucagon, pancreatic polypeptide, somatostatin, and vasoactive intestinal peptide. RESULTS: Chromogranin positive cells were seen in 18 cases with adequate biopsy specimens from the gastric cardia mucosa. These cells were all serotonin positive, but stains for other peptide hormones remained negative. Serotonin positive cells were detected only at the base of foveolae at the periphery of mucous secreting cardiac glands, giving a microscopic appearance resembling that of endocrine cells at the gastric antrum. The presence and numbers of serotonin positive cells did not correlate with chronic inflammation or intestinal metaplasia of the cardiac mucosa. These cells were seen both in Helicobacter pylori positive and negative patients. CONCLUSIONS: Serotonin positive cells appear to be the sole neuroendocrine cell type at the gastric cardia mucosa. These cells may have a role in regulating the physiology of the gastric cardia mucosa and the lower oesophageal sphincter.

Foveolar hyperplasia at the gastric cardia: prevalence and associations.

AIMS: In the gastric antrum and body, foveolar hyperplasia is a feature of reactive gastritis resulting from--for example, duodenogastric bile reflux and the use of non-steroidal anti-inflammatory drugs (NSAIDs). The aim of this study was to examine the occurrence and clinical relevance of gastric cardiac foveolar hyperplasia. METHODS: The study population was drawn from a consecutive series of 1698 patients sent for upper gastrointestinal endoscopy. Only cases without chronic gastritis or Barrett's oesophagus were included. The final study population consisted of 307 patients. RESULTS: Foveolar hyperplasia was seen in the gastric cardiac mucosa in 31 (10%) patients with histologically normal stomach mucosa, but none had endoscopically noticeable hyperplastic polyps. Compared with patients without gastric cardiac hyperplasia, those with hyperplasia more often had chronic inflammation and complete intestinal metaplasia in the junctional biopsies (48% v 77% and 9% v 26%, respectively). Logistic regression analysis revealed that chronic cardiac inflammation (odds ratio (OR), 3.2; 95% confidence interval (CI), 1.3 to 7.8) and intestinal metaplasia of the complete type (OR, 2.8; 95% CI, 1.1 to 7.1) were independent risk factors for cardiac foveolar hyperplasia. In univariate analysis, endoscopic erosive oesophagitis (endoscopy positive gastro-oesophageal reflux disease) and the use of NSAIDs were not related to the presence of foveolar hyperplasia. CONCLUSIONS: Foveolar hyperplasia in the gastric cardiac mucosa occurs in patients with histologically normal non-gastritic stomachs and may develop as a consequence of chronic inflammation limited to the gastro-oesophageal junction ("junctitis"). It is not associated directly with endoscopy positive gastro-oesophageal reflux disease or the use of NSAIDs.

On classification capability of neural networks: a case study with otoneurological data.

We investigated the capability of multilayer perceptron neural networks and Kohonen neural networks to recognize difficult otoneurological diseases from each other. We found that they are efficient methods, but the distribution of a learning set should be rather uniform. Also it is important that the number of learning cases is sufficient. If the two mentioned conditions are satisfied, these neural networks are similarly efficient as some other machine learning methods. The conditions are known in the theory of neural networks [1,2], but not often taken seriously in practice. Both networks functioned as well, excluding the case with several input variables, where the Kohonen neural networks surpassed the perceptron.

Neural network and wavelet recognition of facial electromyographic signals.

The present aim was to explore the possibilities of using neural networks for recognizing significant changes in electrical activity of human facial muscles. We used multilayer perceptron neural networks to recognize bursts of electromyographic signals recorded with bipolar surface electrodes from two subject's facial muscles. Wavelets were applied for the detection of high frequency components of electromyographic signals. Coefficients of wavelets were used as an input to a neural network in order to differentiate bursts from the signals. The results showed that the recognition of bursts was very successful resulting to 84-97 percent total accuracies. The results were very encouraging and suggest further that the measurement of facial muscle activity may be a potentially useful computer input signal, for example, for affective computing which can be seen as a future versatile interaction between the computer and the user.

Towards virtual reality stimulation in force platform posturography.

We developed a stimulation technique on the basis of virtual reality methods for balance investigation performed in balance laboratories of otorhinolaryngological clinics and institutes of occupational health. Such a stimulation technique is greatly progressive in the sense that by creating virtual moving views and "virtual worlds" inside which the subject is located it is possible to make effective stimuli that would be very difficult or even impossible to set in any real environment. We tested our system on healthy subjects and found out that this kind of virtual reality stimulation system is very useful for balance analysis.