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Biomedical subjects

J Partanen

Publications and source records attributed to J Partanen.

At least 73 records · Page 4Linked to original sources
PubMed1999

Distractible children show abnormal orienting to non-attended auditory stimuli.

Event-related potentials were recorded in response to intermittently presented, non-attended trains of identical auditory stimuli in healthy 9-year-old children. In abnormally distractible children (n =24), the first tone in each train elicited a significantly larger N1 vertex response than in the non-distractible children (n 24), suggesting that increased distractibility may be associated with an abnormally strong cerebral orienting towards non-attended stimuli. A later negativity at around 300 ms, which increases in amplitude with stimulus repetition and may thus reflect the building up of a functional neuronal representation of the stimulus properties, was significantly smaller in the distractible than in the non-distractible children. These findings demonstrate that event-related potential measures may be useful in helping to understand the information processing found in distractible children.

Acoustic Stimulation↗
PubMed1999

Effects of acute alcohol infusion on duration and dispersion of QT interval in male patients with coronary artery disease and in healthy controls.

BACKGROUND AND HYPOTHESIS: Alcohol consumption may have advantageous epidemiologic effects but ethanol also increases the risk of sudden coronary death. Prolongation of QT interval has been reported in chronic alcoholics. Long QT period predisposes to serious arrhythmias, and therefore we studied whether acute alcohol intoxication prolongs repolarization in patients with stable coronary artery disease (CAD). METHODS: The effects of acute ethanol steady-state intravenous infusion (0.72 g/kg body weight within 60 min) on QT interval and QT dispersion, assessed by 12-lead electrocardiograms (ECG), were studied in 22 men with stable CAD and in 10 controls. Heart rate variability was measured by Holter recordings. RESULTS: Mean blood alcohol rose to 26.1 +/- 4.3 mmol/l(1.2 +/- 0.2/1000), and was maintained for 2 h. Heart rate was 56 +/- 7 beats/min before and 54 +/- 8 beats/min during ethanol infusion (NS). The heart rate-adjusted QT interval increased on the average 13-23 ms over the 12-lead ECG (p < 0.005). The QT dispersion remained unaltered. The was no difference in the repolarization response in the patients with CAD compared with the controls. The high- and low-frequency components of heart rate variability remained unaltered. CONCLUSIONS: In middle aged men, regardless of the presence of CAD, moderate amounts of alcohol cause prolongation of ventricular repolarization. Changes in the activity of the autonomic nervous system do not seem to explain the observed phenomenon.

Adult↗
PubMed1999

Estimation of the dynamics of event-related desynchronisation changes in electroencephalograms.

A method for the estimation of medium rate transitions of non-stationary electroencephalograms (EEG) is proposed. The method is applicable to such EEG dynamics that are between (a) fast transitions for which segmentation procedures are used and (b) slow transitions for which adaptive filters work properly. The estimation of the transition dynamics is based on a novel time-varying autoregressive model. This model belongs to the class of deterministic regression time-varying autoregressive models and its parametrisation allows only simultaneous transitions in all coefficient evolutions. Data from 22 patients was analysed. The performance of the method is first evaluated with realistic simulations of known transition dynamics and it is shown to be able to track medium-rate transitions. The method is then applied to the estimation of the dynamics of event related desynchronisation. It is shown that the proposed method is able to estimate the transitions which are less apparent, such as from a multi-infarct patient.

Algorithms↗
PubMed1999

Back and hip extensor muscle function during therapeutic exercises.

BACKGROUND: Therapeutic exercises are widely used in the treatment of low back problems. Clinical knowledge about targeting the load in these exercises, however, is insufficient. This study assessed the L2 and L5 level paraspinal and gluteus maximus muscle activities in different therapeutic exercises. Intramuscular and surface electromyography (EMG) measurements were obtained to study whether surface EMG measurements can be used in the assessment of multifidus muscle function. METHODS: Eleven healthy subjects (5 men, 6 women) 21 to 38 years of age volunteered for the study. The subjects performed 18 different therapeutic exercises. During the exercises paraspinal EMG was recorded using fine wire and surface electrodes. The normalized peak and average muscle EMG activities (percentage of amplitude in maximal voluntary contraction [MVC]) during each task were determined. RESULTS: The correlations between the average intramuscular and surface activities of the normalized EMG (% of MVC) at the L2 and L5 levels were .928 and .950, respectively. The peak and average EMG amplitudes of the exercises were below 50% and 25% of MVC, respectively. At the L5 level, the multifidus peak and average EMG amplitudes (% MVC) were higher in women than in men, whereas no significant difference was found at the L2 level. In women, the normalized multifidus EMG amplitude was higher at the L5 level than at the L2 level, whereas no significant difference was found in men. In both sexes, the normalized EMG amplitude was higher in the multifidus than in the longissimus muscle. CONCLUSION: Surface EMG measurements may be used in the assessment of multifidus muscle function. Simple therapeutic exercises are effective in activating the lumbar paraspinal muscles.

Adult↗
PubMed1999

P300 sequence effects differ between children and adults for auditory stimuli.

Variation of the P300 component was studied in normal children and adults during an auditory oddball paradigm. In children, the target stimuli that were preceded by a large number of standard stimuli elicited about twice as large P300 with a significantly shorter latency, a more widespread distribution, and an earlier positivity in the frontal area than those that were preceded by a small number of standard stimuli. The P300 variation was not as marked in adults as in children. Based on the context updating theory of the P300, the finding suggests that a long intertarget interval (ITI) results in a profound decay of the neural representation of the target stimulus in children; consequently, more resources are needed to update the neural representation, and the target may even be processed as a novel input. The P300 variation may provide information about the brain functions related to memory, attention, and orienting in children. This variation should be considered when assessing cognitive brain functions with event-related potentials in children.

Adult↗
PubMed1999

Celiac disease and autoimmune endocrinologic disorders.

Patients with insulin-dependent diabetes mellitus, autoimmune thyroid disease, Addison's disease, and alopecia areata are at increased risk of celiac disease. We investigated whether patients with more than one autoimmune endocrinologic disorder are even more susceptible to celiac disease or have celiac-type mucosal inflammation. All 62 patients found to have such multiple diseases in 1994-1996 were investigated. Small bowel biopsy was performed on all voluntary nonceliac subjects. The villous structure and density of intraepithelial lymphocytes were examined, and HLA-DQ alleles were determined. Seven (11%) patients had celiac disease: six cases were detected earlier and there was one new case; in addition, two had minor villous deterioration and five an increased density of mucosal intraepithelial gammadelta+ T-cells. HLA-DQ2 or DQ8 alleles were found in all subjects with mucosal changes. Patients with multiple autoimmune disorders clearly run an increased risk of developing celiac disease, and some of them have minor mucosal changes compatible with the early signs of the disease.

Addison Disease↗
PubMed1999

CD28/CTLA4 gene region on chromosome 2q33 confers genetic susceptibility to celiac disease. A linkage and family-based association study.

Celiac disease (CD) is a common small intestinal injury caused by sensitivity to gliadin in genetically-predisposed individuals. The only susceptibility locus established is the HLA-DQ. We tested whether the chromosomal region of the CD28/CTLA4 genes on 2q33 is linked to CD. These genes encode receptors regulating the T-lymphocyte activation. Recently, this gene region was reported to be linked to the susceptibility to many autoimmune diseases, including insulin-dependent diabetes (IDDM12locus). It is thus an obvious candidate locus also for CD, since the intestinal injury is mediated by the immune system. Genetic linkage between seven marker loci in this gene region and CD was studied in 69 Finnish families. In the multipoint linkage analysis, the highest non-pararametric linkage score (NPL) was 1.75 (P=0.04) for D2S116, suggesting weak linkage for this candidate locus. To evaluate this finding, an additional 31 families were typed for all markers. In the combined set of 100 families the NPL score for marker D2S116 was 2.55 (P=0.006) and for other markers 1.90-2.47 (P=0.029-0.007), supporting genuine linkage at this region. Significantly, locus D2S116 also showed a clear allelic association in these 100 families (P=0.0001). The transmission/disequilibrium test (TDT) for locus D2S116 gave preliminary evidence for preferential maternal non-transmission of allele *136 to patients (TDTmax=8.3; P<0.05). No paternal deviation was found suggesting that the effect of the locus might be mediated by a sex-dependent factor protective against CD. Our results indicate that the CD28/CTLA4 gene region can contain a novel susceptibility locus for CD and support the hypothesis that CD has an immune system-mediated component. Like the HLA, the CD28/CTLA4 genes appear to be associated with genetic susceptibility to various autoimmune diseases.

Abatacept↗
PubMed1999

Genome scan for predisposing loci for distal interphalangeal joint osteoarthritis: evidence for a locus on 2q.

The genetic contribution to common forms of osteoarthritis (OA) is well established but poorly understood. We performed a genome scan, using 302 markers for loci predisposing to distal interphalangeal joint (DIP) OA. To minimize genetic heterogeneity in our study sample, we identified siblings with a severe, radiologically defined phenotype from the nationwide registers of Finland. In the initial genome scan, linkage analysis in 27 sibships gave a pairwise LOD score (Z) >1.00 with nine of the screening markers. In the second stage, additional markers and family members were genotyped in these chromosomal regions. On 2q12-q13, IL1R1 resulted in Z=2.34 at recombination fraction (theta) 0, allowing a dominant mode of inheritance. Association analysis of markers D2S2264, IL1R1, D2S373, and D2S1789 jointly provided some evidence for a shared haplotype among the affected individuals (P value of.012). Also, multipoint nonparametric linkage analysis yielded a P value of.0001 near the locus IL1R1 and P=.0007 approximately 20 cM telomeric near marker D2S1399, which, in two-point analysis, gave Z=1.48 (straight theta=. 02). This chromosomal region on 2q harbors the interleukin 1 gene cluster and, thus, represents a good candidate region for inflammatory and autoimmune disorders. Three additional chromosomal regions-4q26-q27, 7p15-p21, and Xcen-also provided some evidence for linkage, and further analyses would be justified to clarify their potential involvement in the genetic predisposition to DIP OA.

Adult↗
PubMed1999

HLA-DQ alleles and human papillomavirus DNA in adult-onset laryngeal papillomatosis.

Sixty-two patients with histologically confirmed adult-onset laryngeal papilloma were clinically examined; their HLA class II DQA1 and DQB1 alleles and the presence and type of human papillomavirus (HPV) in their laryngeal papilloma biopsies were determined by polymerase chain reaction-based methods. No differences in the DQA1 or DQB1 frequencies appeared between the patients as a group and the reference population. When the patients were divided into groups according to number of laryngeal procedures performed, no HLA association was noticed with any group, nor did the presence of HPV-6 or HPV-11 DNA in the laryngeal specimen correlate with HLA type. A suggestive association was found between the DQB1 *0501 allele and the 16 patients whose laryngeal biopsy was HPV-negative, but because of the small series, additional patients need to be studied. Earlier, the DQB1 *0501 allele was reported to be protective against cervical cancer, another HPV-associated disease.

Adolescent↗
PubMed1999

Celiac disease and markers of celiac disease latency in patients with primary Sjögren's syndrome.

OBJECTIVE: Many autoimmune diseases occur concomitantly with celiac disease. We investigated prospectively the occurrence of celiac disease and small-bowel mucosal inflammation in patients with primary Sjögren's syndrome. METHODS: A total of 34 patients with primary Sjögren's syndrome and 28 controls underwent small bowel biopsy. Villous morphology, jejunal intraepithelial lymphocytes, and mucosal HLA-DR were evaluated and DQA and DQB alleles, serum antiendomysial, and antigliadin antibodies were examined. RESULTS: Five (14.7%) of 34 Sjögren's syndrome patients were found to have celiac disease. The density of jejunal intraepithelial gammadelta+ T cells was increased in all celiac and in four nonceliac patients. All celiac patients, 69% of nonceliac Sjögren's syndrome patients, and 11% of control subjects showed enhanced HLA-DR expression (p < 0.001). HLA DQ2 was present in 19 (56%) patients with Sjögren's syndrome, including all five with celiac disease. CONCLUSIONS: The findings show a close association between Sjögren's syndrome and celiac disease. Even among nonceliac patients with primary Sjögren's syndrome, an ongoing inflammation is often present in the small bowel mucosa.

Autoimmune Diseases↗
PubMed1999

Molecular characterization of two mutations in platelet glycoprotein (GP) Ib alpha in two Finnish Bernard-Soulier syndrome families.

Bernard-Soulier syndrome (BSS) is a rare hereditary bleeding disorder and macrothrombocytopenia which is caused by a defect in the platelet glycoprotein Ib/IX/V (GP Ib/IX/V) complex, the receptor for von Willebrand factor and thrombin. Here we report the molecular basis of the classical form of BSS in two unrelated Finnish patients, both with a life-long history of severe bleeding. Flow cytometry and immunoblotting showed no expression of GP Ib/IX, GP Ib alpha, GP Ib beta or GP IX (less than 10%) in the patients' platelets. No expression of GP V (< 10%) was observed in propositus 1, but a residual amount was found in propositus 2 (24%). DNA sequencing analysis revealed that propositus 1 was compound heterozygous for a two-base-pair deletion at Tyr505(TAT) and a point mutation Leu129(CTC)Pro(CCC) in the GP Ib alpha gene. Propositus 2 was homozygous for the Tyr505(TAT) deletion. The nine relatives who were heterozygous for either of the mutations also had low levels of GP Ib alpha (74-90%). Hence, Bernard-Soulier patients homozygous or compound heterozygous for Tyr505(TAT) are severely affected. Interestingly, both mutations have independently been found in three other families in previous reports, suggesting their ancient age or mutational 'hot spot'.

Bernard-Soulier Syndrome↗
PubMed1999

Variant Bernard-Soulier syndrome due to homozygous Asn45Ser mutation in the platelet glycoprotein (GP) IX in seven patients of five unrelated Finnish families.

Bernard-Soulier syndrome (BSS), a rare bleeding disorder with macrothrombocytopenia, is caused by a defect of the platelet glycoprotein (GP) Ib/IX/V complex. Here we report a variant form of BSS in eleven patients of five unrelated families who originate from a particular area of Finland. The differential diagnosis from idiopathic thrombocytopenic purpura was difficult. Bleeding symptoms were epistaxis and haematomas debuting in childhood, but no spontaneous, severe bleeding episodes were reported. The platelet count varied from 43 to 81x10(9)/l. Screening the entire GP Ibalpha, GP Ibbeta, GP IX and GP V genes revealed a recurrent homozygous Asn45Ser mutation in GP IX in all probands. Flow cytometry showed markedly reduced expression of GP Ib (<10%), and only moderately reduced expression of GP IX (24-36%) and GP V (38-49%). The expression of subunits seemed to vary independently from the normal polymorphisms. Heterozygotes did not differ significantly from controls by their GP Ib/IX/V expression. Since the Asn45Ser mutation has also been reported in three other kindreds of northern and central European origin, this study reveals that instead of being a mutation hot spot, it may be ancient and scattered in Europe. Moderate, chronic thrombocytopenia should be carefully studied to diagnose variant BSS correctly from treatment resistant idiopathic thrombocytopenia.

Amino Acid Substitution↗
PubMed1999

Interaction of the TEK and TIE receptor tyrosine kinases during cardiovascular development.

TEK (TIE2) and TIE (TIE1) are structurally related receptor tyrosine kinases expressed in endothelial cells and their precursors. Genetic studies in the mouse have revealed essential functions of both receptors in angiogenic expansion of the vasculature during development. As previously shown, mouse embryos homozygous for a disrupted Tek allele die by day 10.5 of embryogenesis due to endocardial defects, hemorrhaging, and impaired vascular network formation. Furthermore, TIE is required cell autonomously for endothelial cell survival and extension of the vascular network during late embryogenesis. Here we have investigated possible redundancy in the TEK and TIE signalling pathways during vascular development. Vasculogenesis proceeds normally in embryos lacking both TEK and TIE, although such embryos die early in gestation of multiple cardiovascular defects. Mosaic analysis revealed an absolute requirement for TEK in the endocardium at E10.5, whereas TEK and TIE are dispensable for the initial assembly of the rest of the vasculature. In contrast, both receptors are required in the microvasculature during late organogenesis and in essentially all blood vessels of the adult. This analysis demonstrates essential functions for TEK and TIE in maintaining the integrity of the mature vasculature.

Animals↗
PubMed1999

Expression of HSP-65 in jejunal epithelial cells in patients clinically suspected of coeliac disease.

BACKGROUND: Coeliac disease (CD) can be classified both clinically and biologically an autoimmune disease. A close relationship obtains between heat shock proteins (HSPs) and numerous autoimmune diseases. HSPs are overexpressed when protecting the host against environmental insult. We sought here to establish whether dietary gluten is such a stress stimulus in patients clinically suspected of CD, and whether the expression of HSP-65 associates with densities of intraepithelial gammadelta+ T cells and/or with expression of mucosal HLA-DR. METHODS: Seventy-eight children with clinical suspicion of CD underwent a jejunal biopsy. Monoclonal antibodies were used to stain jejunal epithelial HSP-65, intraepithelial lymphocytes and mucosal HLA-DR. Serum IgA-class endomysial autoantibodies (EMA) were measured by an indirect immunofluorescence method. CD susceptibility HLA DQA1*0501 and DQB1*0201 alleles (HLA DQ2) were determined. RESULTS: Enhanced expression of epithelial cell mitochondrial HSP-65 was found in 80% (16/20) of coeliacs and in 24% (14/58) of children excluded for the disease, but in only 7% (2/28) of control subjects (p < 0.001, p = 0.049, respectively). Children with enhanced expression of HSP-65 had significantly higher gammadelta+ T cell densities than those with normal HSP-65 expression. A clear association between HSP-65 and serum IgA-class EMA were also ascertained in patients with normal jejunal mucosal morphology. HLA DQ2 positivity did not correlate with the HSP-65 expression. CONCLUSIONS: Gluten might be an environmental insult not only in CD patients but also in some patients excluded for the disease on biopsy. Enhanced expression of epithelial cell stress proteins might be an indicator of such an insult.

Adolescent↗
PubMed1999

Increased density of jejunal gammadelta+ T cells in patients having normal mucosa--marker of operative autoimmune mechanisms?

Both from a clinical and a biological point of view, coeliac disease can be classified among the autoimmune diseases, or one could suspect autoimmune mechanisms to be operative in the disease. The aim of the present study was to find evidence for mucosal markers of coeliac disease latency in patients clinically suspected but on routine biopsy excluded for the disease. Monoclonal antibodies were used to stain jejunal intraepithelial lymphocytes and mucosal HLA-DR. Serum IgA-class reticulin autoantibodies were measured by an indirect immunofluorescence and gliadin antibodies by an enzyme-linked immunosorbent assay method. The DQA1*0501 and DQB1*0201 alleles were determined. Twenty-seven of 107 consecutive patients had coeliac disease. Altogether 39 of 79 (49%) children with normal jejunal mucosa had an increased density of intraepithelial gammadelta+ T cells (> or = 4.4 cells/mm). IgA-class reticulin autoantibodies were positive in 18 (23%) of the children excluded for coeliac disease. The antibody positivity was mostly seen in patients carrying the DQAI 0501 and DQB1*0201 alleles. Also, reticulin autoantibody-positive children having normal jejunal mucosal morphology had significantly higher densities of intraepithelial gammadelta+ T cells than antibody negative ones. On 1.5-4.5 year follow-up four out of 18 (22%) children primarily excluded for coeliac disease showed mucosal deterioration and coeliac disease. Many patients clinically suspected of coeliac disease but having normal jejunal mucosa show markers of coeliac disease latency which may be gluten-induced indicating autoimmune mechanisms to be operative in the gut.

Adolescent↗
PubMed1998

Opposite phenotypes of hypomorphic and Y766 phosphorylation site mutations reveal a function for Fgfr1 in anteroposterior patterning of mouse embryos.

Intercellular communication is needed for both the generation of the mesodermal germ layer and its division into distinct subpopulations. To dissect the functions of fibroblast growth factor receptor-1 (FGFR1) during mouse gastrulation as well as to gain insights into its possible roles during later embryonic development, we have introduced specific mutations into the Fgfr1 locus by gene targeting. Our results show functional dominance of one of the receptor isoforms and suggest a function for the autophosphorylation of site Y766 in the negative regulation of FGFR1 activity. Y766F and hypomorphic mutations in Fgfr1 generate opposite phenotypes in terms of homeotic vertebral transformations, suggesting a role for FGFR1 in patterning the embryonic anteriorposterior axis by way of regulation of Hox gene activity.

Alleles↗