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Biomedical subjects

J Partanen

Publications and source records attributed to J Partanen.

At least 199 records · Page 11Linked to original sources

Modulation of fibroblast growth factor receptor expression and signalling during retinoic acid-induced differentiation of Tera-2 teratocarcinoma cells.

We have analyzed the regulation of fibroblast growth factor receptors (FGFRs) during retinoic acid (RA) induced differentiation of Tera-2 human embryonal carcinoma cells. Undifferentiated Tera-2 cells expressed mRNAs for all four known FGFRs. Their differentiation led to loss of FGFR-4 mRNA expression and mRNA levels for FGFR-2 and FGFR-3 were considerably downregulated, whereas the mRNA levels for FGFR-1 remained unaltered. A substantial decrease in binding of K-FGF was found to occur upon RA-induced differentiation of the cells. In undifferentiated Tera-2 cells FGF stimulation caused an increase of c-fos mRNA, and c-jun mRNAs, but no increase of junB mRNA, whereas in the differentiated cells, FGFs strongly stimulated the expression of all three genes. Thus differentiation of the Tera-2 cells leads to marked changes in FGFR gene expression as well as to complex alterations in their responses to exogenous FGFs.

Cell Differentiation↗

Tibial muscular dystrophy. Late adult-onset distal myopathy in 66 Finnish patients.

OBJECTIVE: To clarify the classification of two previously reported groups of patients with anterior tibial distal dystrophy, to find additional patients with the disease, and to describe the clinical features of this disease. DESIGN: National survey of the records of patients with neuromuscular diseases in Finland. Findings of selected patients were compared with those of previously reported cases. PATIENTS: Thirty-six previously described patients and 30 additional patients from the current survey, with 41 symptomatic patients and 25 subjectively asymptomatic affected relatives. RESULTS: There were 66 patients with late adult-onset tibial muscular dystrophy. Symptoms appear after the age of 35 years with reduced ankle dorsiflexion, and progress is slow without marked disability. Facial muscles, upper extremities, and proximal muscles are usually spared. Muscle biopsy results reveal nonspecific dystrophic changes in clinically affected muscles, and frequently severe adipose replacement in the anterior tibial muscles occurs. Asymptomatic muscles have mild myopathic changes only. Vacuolar degeneration is detected in a minority of patients. Electromyography shows profound myopathic changes in the anterior tibial muscle, but extensor brevis muscles are well preserved. Computed tomography or magnetic resonance imaging of muscles discloses marked involvement of tibial extensor muscles and focal patches of fatty degeneration in various asymptomatic muscles. Pedigree data suggest autosomal dominant inheritance. CONCLUSIONS: Tibial muscular dystrophy might represent a new form of distal myopathy and it is rather common, at least in Finland.

Adolescent↗

Effects of 45-Hz magnetic fields on the functional state of the human brain.

The influence of sinusoidal 45-Hz magnetic fields on the brain functions of 20 volunteers was investigated in a double-blind study using spectral analysis of EEG and measurements of Omega potentials and reaction time (RT). The field strength was 1,000 A/m (1.26 mT) and the duration of exposure was 1 h. Ten volunteers were exposed to a continuous field and ten received an intermittent exposure (1 s on/l s off). Each person received one real and one sham exposure. One half of the volunteers got the real exposure first and the sham treatment after at least 24 h. For the rest, the sequence was inverse. The measurements of EEG, omega potentials and RT were performed before and after each exposure. Several statistically significant changes were observed, most of them after intermittent exposure. In the EEG, an increase of alpha (7.6-13.9 Hz) activity and a decrease of delta (1.5-3.9 Hz) activity were observed. Beta waves (14.2-20 Hz) increased in the frontal derivations as did the total power in occipital derivations. The mean and peak frequencies of EEG increased mainly in the frontal derivations. No direct effects on RT were seen. Learning to perform the RT test (decrease of RT in repeated trials), however, seemed to be affected by the exposure. The persons who received real exposure first learned more slowly than those who got sham exposure first. Further experiments are necessary to confirm the findings and for understanding the mechanisms of the effects.

Adult↗

Influence of 50 Hz electric and magnetic fields on the human heart.

This investigation studied the effect of 50 Hz electric and magnetic fields on the human heart. The electrocardiograms of 27 transmission-line workers and 26 male volunteers were recorded with a Holter recorder both in and outside the fields. The measurements took from half an hour to a few hours. The electric field strength varied from 0.14 to 10.21 kV/m and the magnetic flux density from 1.02 to 15.43 microT. Analysis of the ECG recordings showed that extrasystoles or arrhythmias were as frequent outside the field as in the field. In some cases a small decrease in heart rate was observed after field exposure.

Adolescent↗

Mismatch negativity area and age-related auditory memory.

The deviant tones embedded in a sequence of standard tones elicit an event-related potential (ERP) component called mismatch negativity (MMN). Because MMN is partly overlapped by other ERP components at 100-200 msec latency (N1 and P2) and its shape varies, MMN peak latency and amplitude may be ambiguous. We used the difference area between the deviant and standard ERP to evaluate the age and interstimulus interval (ISI) dependence of MMN. Sequences of standard (85%) and deviant (15%) tones were presented to 27 normal subjects (age 18-85 years) using 1 sec and 3 sec ISIs and to 6 young subjects using an additional ISI of 5 sec. With this method MMN was clearly seen in 26 out of 27 healthy subjects (96.3%). MMN area was quite stable regardless of age with 1 sec ISI. With 3 sec ISI MMN area was significantly smaller in the old than in the young subjects. This may reflect the shortening of the sensory auditory memory trace with increasing age.

Acoustic Stimulation↗

Influence of short-term exposure of magnetic field on the bioelectrical processes of the brain and performance.

The influence of an extremely-low-frequency (ELF) magnetic field on the bioelectrical processes of brain and performance was studied by EEG spectral analysis, auditory-evoked potentials (AEP), reaction time (RT) and target-deletion test (TDT). Fourteen volunteers were exposed for 15 min to an intermittent (1 s on/off) 45-Hz magnetic field at 1000 A/m (1.26 mT). Each person received one real and one sham exposure. Statistically significant increases in spectral power through alpha- and beta-bands, as well as in mean frequency of the EEG spectrum were observed after magnetic field exposure. Field-dependent changes of N100 were also revealed. No changes in the amplitudes or latencies of the earlier peaks were observed. No direct effects on RT, nor on TDT performance were seen. However, practice effects on RT (decrease of RT in the course of the test-sessions) seemed to be interrupted by exposure to the magnetic field.

Brain↗

Age-related cognitive decline and electroencephalogram slowing in Down's syndrome as a model of Alzheimer's disease.

We studied quantitative electroencephalogram and neuropsychological performance in an aging series of 31 patients with Down's syndrome and compared the findings with those of 36 patients with probable Alzheimer's disease and age-matched controls. We found an age-related decline of cortical functions and slowing of the electroencephalogram in Down's syndrome patients aged from 20 to 60 years. Slowing of the electroencephalogram, i.e. the decrease of the peak frequency, was significantly related to Mini-Mental status scores, and visual, praxic and speech functions, as well as memory in the Down patients, similar to the Alzheimer patients. Similar correlations were not demonstrated for young or elderly controls. This study provides neuropsychological and electrophysiological data to suggest that studying Down's syndrome patients of different ages can serve as a model for progression of Alzheimer's disease.

Adult↗

Local denervation atrophy of paraspinal muscles in postoperative failed back syndrome.

Impairment and disability after back surgery is a common diagnostic and therapeutic problem. For the most part the reasons are unclear. Of 178 patients who had undergone laminectomies 2-5 years earlier, 14 patients with good recovery and 21 patients with poor recovery but no evidence of restenosis on computed tomography were selected by the Oswestry index. According to radiologic, neurophysiologic, and muscle biopsy evidence most patients (13 of 15 studied) suffering from the severe postoperative failed back syndrome had dorsal ramus lesions in one or more segments covered by the scar and local paraspinal muscle atrophy at the corresponding segments. Disturbed back muscle innervation and loss of muscular support leads to the disability and increased biomechanical strain and might be one important cause to the failed back syndrome. It may be possible to develop operating techniques that save back muscle innervation better than the usual ones.

Adult↗

Failures in alcohol policy: lessons from Russia, Kenya, Truk and history.

The paper draws upon the recent developments of alcohol policy in the ex-Soviet Union and in Africa, especially Kenya. According to the standard criteria of success, both are to be regarded as total or near-total failures. The examination of these cases will, consequently, reveal some of the factors that are essential prerequisites for carrying out successful alcohol policies. It will lead to considerations concerning the approaches and problems of alcohol research; to a discussion about the marginalization of alcohol and drinking in our Western societies; to another look at the tasks of alcohol policies (based also on experiences in Truk, Federated States of Micronesia); and, finally, to a rather modest view about the role of alcohol policy in general.

Alcohol Drinking↗

HLA-linked heat-shock protein 70 (HSP70-2) gene polymorphism and celiac disease.

The restriction enzyme Pstl showed a two-allele restriction fragment length polymorphism (RFLP) marker when DNA polymorphism of the gene G8, a novel major histocompatibility complex (MHC) class III gene, was screened. The gene G8 is located ca. 4 kb centromeric of the heat-shock protein 70 (HSP70) gene cluster. A more detailed mapping indicated that the polymorphic restriction site is actually located in the coding region of the adjacent HSP70-2 gene, where it has been earlier reported to cause a silent mutation. To estimate the frequency of this polymorphism in the normal population, 95 blood donors were analyzed: The gene frequency of the 8.5 kb (designated 'L') allele was 0.45 and that of the 8.65 kb ('U') allele 0.55. However, when 19 families with patients suffering from celiac disease were studied, the gene frequencies in the affected haplotypes (L = 0.76, U = 0.24) significantly deviated from those observed in the normal population and in the non-affected MHC haplotypes of these families (L = 0.48, U = 0.52). However, the association results from a strong association between the allele 'L' and the MHC haplotype HLA B8 DR3, a known suspectibility marker of celiac disease. Only one patient, in fact, was negative for the well-established class II haplotype markers DR3 or DR7. The data therefore confirm the crucial role of MHC class II in suspectibility to celiac disease, but due to a strong linkage disequilibrium within MHC the role of MHC class III genes in disease associations can not be ruled out.

Autoimmune Diseases↗

An HLA-DR typing protocol using group-specific PCR-amplification followed by restriction enzyme digests.

A simple PCR-based protocol for HLA-DR typing suitable for a routine practice is described. The method involves, first, a PCR amplification with seven different, group-specific (DR1, DR2, DR4, DR7, DR9, DR10, and DR3+5+6+8) primer-pairs, and second, typing of HLA-DR allele more exactly in DR1, DR2, DR4, and DR3+5+6+8 groups by digestion of PCR products with restriction enzymes distinguishing different HLA-DR types within each of the groups. Altogether 24 HLA-DR alleles, or any combination of these, can be typed. The whole procedure, starting from a blood sample, can be carried out during a single working-day. The method was tested by typing a set of homozygous cell lines, as well as a local panel previously typed by PCR/oligotyping. Also, 227 patients waiting for transplantation were typed to test the method in a routine setting. The results suggest that this kind of approach gives reliable HLA-DR types and works well in the routine use.

Alleles↗

Reappraisal of HLA in multiple sclerosis: close linkage in multiplex families.

Although association between multiple sclerosis (MS) and HLA-DR2,DQw6 has been well documented, family studies have not established linkage to HLA. Here we have (1) carried out an HLA-DQA1, -DQB1 association study in unrelated patients and controls, and (2) analyzed linkage between MS and HLA in multiplex families using both nonparametric and parametric methods. The subjects and families were derived from the genetically homogeneous Finnish population, and 14 of the 21 families came from a high-risk area with exceptional familial clustering of cases. In the association study, the frequencies of the alleles DQA1*0102 and DQB1*0602 (encoding DR2-associated DQw6 antigen) were significantly increased in MS patients compared to controls. In the families, we observed that the segregation of MS with DQA1*0102 and DQB1*0602 was not HLA haplotype specific, i.e., these alleles were frequently transmitted to MS relatives on different parental haplotypes. Consequently, we found strong evidence for linkage between MS and HLA only when the haplotype-independent segregation of the MS-associated alleles was controlled. This observation may partially explain the lack of linkage evidence in previous family studies. The highest LOD scores were obtained to the DQA1 locus (LODmax = 6.43, theta = 0.00). The linkage analyses suggest that both the patients' HLA haplotypes may contribute to MS susceptibility. In one of a patient's haplotypes, the susceptibility locus was closely associated with DQA1*0102 and DQB1*0602, whereas in the other haplotype no association with any of the individual candidate loci was found. These results demonstrate, for the first time, a close linkage between MS and HLA, and raise the possibility of distinct HLA-linked susceptibility genes in MS.

Base Sequence↗

The human ryk cDNA sequence predicts a protein containing two putative transmembrane segments and a tyrosine kinase catalytic domain.

The human ryk tyrosine kinase cDNA was originally identified as a PCR-amplified cDNA fragment (JTK5) from K562 leukemia cells and found to represent a ubiquitously expressed gene (Partanen et al., 1990). The open reading frame of human ryk, reported here, encodes a novel type of putative tyrosine kinase of 607 amino acid residues, having two potential transmembrane domains and homology to receptor tyrosine kinases, such as met (HGF/SF-R) and IGF-1R, in its catalytic domain. The gene maps to human chromosome 3q11-25. Expression of the 3.4 kb ryk mRNA was found in all human adult tissues examined.

Amino Acid Sequence↗