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Biomedical subjects

T Korhonen

Publications and source records attributed to T Korhonen.

At least 73 records · Page 4Linked to original sources
PubMed1992

A three-year follow-up study of patients in a day treatment program.

A 3-year follow-up study was conducted with 73 psychiatric patients in a Finnish day treatment program. The treatment outcome for these patients, who carried a wide range of diagnoses, was measured using psychiatric rehospitalization as a criterion. There were a large number of patients who were disabled and had been receiving social security benefits during the 3 years following discharge from the day treatment program. The rehospitalized cases involved mainly patients with a diagnosis of schizophrenia or personality disorder; use of neuroleptic medication was significantly associated with poor results. The numbers of psychiatric hospitalizations before treatment in the day treatment program in 1985 was found to be independent of hospitalizations during follow-up years. The results of the study support the claim that day treatment does not increase the likelihood of rehospitalization. Day treatment may reduce the length of stay during rehospitalization, but it is also clear that it cannot stop the rehospitalization of patients with severe diagnoses.

Chi-Square Distribution↗
PubMed1991

Screening for a prevalent LDL receptor mutation in patients with severe hypercholesterolaemia.

A rapid new method for the diagnosis of familial hypercholesterolaemia (FH) detects the deletion extending from intron 15 to exon 18 in the low density lipoprotein (LDL) receptor gene, i.e. the FH-Helsinki mutation responsible for a major portion of FH in Finland. Amplification of the DNA sequences flanking the deletion in the mutant allele generated an abnormal 391-bp product that could be detected by photographing the ethidium-bromide-stained agarose gel after electrophoresis. Up to 50 samples can be analysed in about 8 h. The method was validated by comparison with a routine Southern blot technique. The deletion was found in 23 out of 37 patients with a clinical diagnosis of FH (62%) and in 2 out of 73 with primary hypercholesterolaemia without a clinical diagnosis of FH within a series of 110 consecutive patients with severe hypercholesterolaemia (serum cholesterol greater than 8 mmol/l). The data indicate that DNA techniques may provide a supplementary aid for the routine diagnosis of FH and suggest that the polymerase chain reaction in particular may offer major advantages because of its simplicity and rapidity.

Adult↗
PubMed1991

A method for rapid implantation of multielectrode systems.

The implantation of several chronic electrodes at the same time was needed for the studies in which both evoked slow potential and multiple unit neural activity of different brain sites were recorded during classical conditioning in freely moving cats. The recording electrodes were made of 25-75 microns insulated stainless steel or nichrome wires which were inserted into a thin hypodermic needle of a fixed, calibrated length. The fast implantation system described here is based on the use of a stereotaxic frame as a stand for a drill and as a support for an electrode holder with which the electrodes were implanted through precision holes drilled directly according to the coordinates of the brain atlas. The connecting pins of each electrode were inserted to a connector during implantation. The described implantation system allows short distances (0.5 mm) between electrode shafts and free determination of the depth of each electrode. Because fixing of an individual electrode with dental cement to the skull is not needed during the initial phase and the precalibrated electrodes need no adjustments during implantation, considerable time savings can be achieved.

Animals↗
PubMed1991

Three-dimensional hall effect accelerometer for recording head movements of freely moving laboratory animals.

A Hall effect device was constructed for a measurement of head movements in three spatial dimensions during classical conditioning experiments in cats. A Hall sensor was used to detect movements of a magnetic fragment floating in a small (15 x 15 mm) cube. The magnetic fragment was kept in the centre of the sealed cube with a thin coil spring which was filled with thin oil for damping excessive afteroscillations. A comparison of this device to a commercial accelerometer showed that the accuracy of the Hall device is sufficient for the movement recordings and that the device is sensitive also to slowly accelerating movements. The construction is compact and can be easily mounted, for example, on the head stage of a freely moving animal.

Animals↗
PubMed1991

Asymmetries in classically conditioned head movements and cingulate cortex slow potentials in cats.

Presuming that conditioned head movements in the cat indicate a preference for a specific direction, asymmetries were also expected to be found in bilaterally recorded cingulate cortex slow potentials to a symmetrical tone stimulus during discriminative conditioning. Conditioned stimuli (CS, 1000 and 2500 Hz tones) were delivered through two miniature loudspeakers fitted to the head in front of both ears. The unconditioned stimulus (US) was an electrical stimulation of either the left or right lateral hypothalamus yielding, in addition to its rewarding effects, an unconditioned head turning response (UR) either to the left, right, forwards or upwards. Discrimination learning appeared as more extended and more rapid headturns and greater negativity in the cingulate cortex to the CS+ than to the CS-. The preferred conditioned behavioral response (CR) was a headturn to the left in 11 of 12 cats accompanying increased negativity in evoked slow potentials in the right cingulate cortex during the 128-324 ms period after the CS onset. No differences in the movements and in the cingulate potentials were found between the left versus right US stimulations. The results showed that regardless of the direction of the original unconditioned head movement, the direction of the CR was at the end of the training period to the left in 11 out of the 12 cats. Larger evoked slow potentials observed in the right cingulate cortex which were not present in the baseline measurements suggest a population bias between the hemispheres.

Animals↗
PubMed1990

The etiology of XX sex reversal.

The primary testis-determining function is exerted by a gene in the sex-determining region of the human Y chromosome. This gene is termed the sex-determining factor or TDF. A zinc finger gene, ZFY, residing in this region has been cloned and characterized. It is a candidate for TDF. A challenge to future molecular research is to clarify the function of a zinc finger gene on the X chromosome, ZFX, that shows high structural similarity to ZFY. Furthermore, the existence of other genes involved in sex determination is likely but so far unproven. Sex reversal leading to testes in apparently XX individuals (XX males) is most often due to the presence of TDF on the paternally derived X chromosome. The abnormality arises during meiosis in the father when an abnormal exchange leads to the transfer onto the X of the entire pseudoautosomal region plus a portion of the Y chromosome-specific region including TDF from the Y. An XX male resulting from such an exchange is described. 10-20% of XX males do not have Y DNA. Two major mechanisms to explain such Y(-) XX males are discussed. First, several published pedigrees show clear-cut dominant autosomal or X chromosomal inheritance of XX maleness. These patients are always Y(-) and usually have sexual ambiguity. This indicates the existence of other genes, obviously 'downstream' from TDF, that when mutated can trigger testis determination. Nothing concrete is presently known about these putative genes, but their phenotypic effect is slightly different from that of TDF. Second, mosaicism with a prevalent XX lineage and a hidden or scarce lineage containing a Y chromosome can explain some apparently Y(-) XX males. Two XX/XXY mosaic patients are described in detail. In one, only a combination of DNA hybridization and cytogenetic studies led to the discovery of the XXY cell line. In conclusion, XX sex reversal in man is caused by at least 3 mechanisms, viz. abnormal Y-X interchange, genes other than TDF, and mosaicism.

Adolescent↗
PubMed1990

Motor ability and personality with reference to soccer injuries.

Thirty-seven male soccer players performed a series of motor ability tests and answered the Sixteen Personality Factor Questionnaire (the 16PF). A past-injury examination and interview was performed by a physician and occurrence of injuries was followed up prospectively for one year. Stepwise regression analyses revealed significant associations between past injuries and long reaction time as well as personality factors N (astute) and H (shy). We conclude that both weakness of motor abilities, especially long reaction time, and a specific personality type may predispose a player to soccer injuries.

Adolescent↗
PubMed1989

Conditioned orienting (alpha) and delayed behavioral and evoked neural responses during classical conditioning.

A differentiation of short-latency (alpha) and long-latency (delayed) classically conditioned behavioral and evoked neural (hippocampal) responses was attempted. Further, facilitation and retardation of these responses were studied in an experimental design in which 10 paired conditioning sessions either preceded (CC-CO group) or followed (CO-CC group) 10 randomly unpaired presentations of conditioned stimuli (CS) and unconditioned stimuli (UCS). A 2024-ms tone (1000 Hz) was delivered directly through a miniature earphone to the left ear, eliciting an orienting head movement ('alpha' response) to the left. The unconditioned stimulus (UCS) was a direct 1024-ms stimulation of the lateral hypothalamic area overlapping the CS (delayed paradigm) so that both stimuli terminated simultaneously. The UCS elicited approach behavior and a specific head movement in each animal. The latency and the direction of the head movement were used as criteria for a differentiation of the short-latency and long-latency conditioned responses (CR). All cats showed conditioned short-latency responses. Pairing specific long-latency head movements were observed in 10 of 13 cats and 6 of them showed a long-latency CR which was a head movement to the right, while the short-latency CR on the same trials was a head movement to the left. Hippocampal (subiculum, dentate fascia and CA1) evoked responses also showed pairing specific CRs appearing as increased negativity (short-latency CR), or increased positivity (long-latency CR). Additional reversed stimulus order (backward) sessions supported an assumption of the different nature of the short-latency and long-latency CRs: the long-latency CRs showed extinction while the short-latency CRs remained. The unpaired pre-exposure to the CSs and UCSs in the CO-CC group resulted in the retarded acquisition of the behavioral responses during the subsequent paired sessions.

Animals↗
PubMed1989

Behavioral and neural characteristics of short-latency and long-latency conditioned responses in cats.

Head movements to the conditioned stimulus (a tone CS to the left ear) were studied in 6 cats. An attempt was made to differentiate an orienting, short-latency (alpha) response from the long-latency conditioned (delayed) response. The unconditioned stimulus (UCS) was a brain stimulation to the lateral hypothalamus eliciting, in addition to orienting and approach behavior, a specific, stereotypical head movement. These behavioral characteristics of the unconditioned head movement were used for differentiating it from the conditioned short-latency head movement. Paired conditioning and randomly unpaired control sessions (5 daily sessions each) were given in balanced order to each animal. Evoked neural responses in the hippocampus and cingulate cortex were recorded simultaneously to compare the time-amplitude characteristics of evoked responses to earlier findings in multiple-unit recordings. The results supported the differentiation of the behavioral responses. The time-amplitude course of the evoked neural responses showed complex changes, appearing as an increase in the negativity during the alpha-response period (150- to 450-ms interstimulus interval [ISI]) and as an increase in the positivity during the long-latency period (700- to 1,000-ms ISI + 150- to 450-ms UCS period) on omitted-UCS (CS-alone test) trials.

Alpha Rhythm↗
PubMed1989

Endocrine abnormalities in patients with adrenal tumours incidentally discovered on computed tomography.

To determine endocrine activity of adrenal tumours incidentally discovered on C.T., we examined 20 consecutive patients. They underwent thorough hormonal assessment and scintigraphic scanning with radioactive cholesterol under dexamethasone suppression (19 patients). Biochemical findings compatible with cortisol hypersecretion were detected in 5 patients. One patient had reduced reserves of cortisol secretion and one had hyporeninemic hypoaldosteronism. The scintigraphy showed no uptake in 10, unilateral uptake in 4, and bilateral uptake in 5 patients. In 3 patients the finding was unilateral on CT. but bilateral on scintigraphy. Signs of autonomous cortisol production were more common among patients who had uptake on scintigraphy. At the operation of 8 patients only benign lesions were found. During the follow-up (9 to 49 months) of the 12 unoperated patients, the tumour disappeared in one and remained unchanged in the others. No changes occurred in the biochemical findings except in one patient whose cortisol response to 1 mg of dexamethasone became abnormal. Since slight hypercortisolism or a bilateral disease often exists behind an incidentally discovered adrenal tumour, we emphasize the importance of careful assessment of cortisol metabolism and a scintigraphic scanning under dexamethasone suppression in the examination of these patients.

17-Ketosteroids↗
PubMed1988

Stopping insulin treatment in middle-aged diabetic patients with high postglucagon plasma C-peptide. Effect on glycaemic control, serum lipids and lipoproteins.

We studied the successfulness of stopping insulin treatment in middle-aged diabetic patients aged 45-64 with a high postglucagon C-peptide level and the effects of this change on glycaemic control, serum lipids and lipoproteins. Insulin treatment was successfully stopped in 15 of our 22 patients who satisfied the inclusion criteria for the study and were selected on the basis of a computer file including practically all diabetic patients treated with insulin in the Kuopio University Central Hospital region (population base 250,000 inhabitants). Insulin therapy was restarted in seven patients during the first 3 months after discharge. During the following 9 months insulin therapy was restarted in another three patients so that after a 1-year follow-up period half of the diabetic patients whose insulin therapy was stopped had been switched back to insulin. Insulin therapy was seldom successfully stopped if the postglucagon C-peptide value was under the limit of 1.0 nmol/l. Glycaemic control did not change during the follow-up, although there was a significant weight loss in diabetic patients. No changes were observed in serum lipids or lipoproteins with the exception of LDL cholesterol, which showed a significant reduction during the 3-month follow-up. In conclusion, insulin therapy can often be successfully stopped in patients with postglucagon C-peptide over the limit of 1.0 nmol/l without worsening of glycaemic control and without unfavourable changes in serum lipid and lipoprotein levels.

C-Peptide↗
PubMed1988

Characterization and purification of the F17 adhesin on the surface of bovine enteropathogenic and septicemic Escherichia coli.

The F17 antigen from bovine enterotoxigenic Escherichia coli strain (E coli 25KHO9), which adhered to calf intestinal villi, was isolated. An enterotoxin-negative derivative (25KHO9st) was used for further studies. Using an immunogold-labeling technique, the F17 antigen was characterized as a fimbrial protein. Pure fimbriae with a subunit molecular weight of 20,000 were obtained by homogenization and use of a sucrose gradient. The adhesion of E coli 25KHO9st was mediated by the F17 fimbriae, as both F17 antibodies and F17 protein blocked the adhesion of the strain 25KHO9st. The F17 fimbriae were serologically distinct from K88, K99, F41, and 987P fimbriae and did not agglutinate bovine, ovine, guinea pig, human, or chicken erythrocytes. Peptide fingerprint analysis revealed F17 and F(Y) adhesins to be homologous, if not identical.

Adhesins, Escherichia coli↗
PubMed1987

Lack of effect of hepatic enzyme induction on metabolic control in patients with type 2 (non-insulin-dependent) diabetes.

A placebo-controlled, double-blind crossover study was carried out in 11 non-insulin-dependent (type 2) diabetic patients to find out the effects of a hepatic enzyme inducer (phenobarbital, 100 mg/day for 2 months) on the metabolic control, plasma C-peptide, insulin, serum, and lipoprotein lipid levels. Phenobarbital induced a significant increase in hepatic antipyrine metabolizing activity, but no significant changes were found in fasting or postload blood glucose, plasma C-peptide, or insulin levels during the study. There was a significant increase in serum total cholesterol, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol, as well as in serum total and very low-density lipoprotein triglycerides, during phenobarbital treatment as compared with placebo.

Adult↗
PubMed1987

Efficacy of dietary instructions in newly diagnosed non-insulin-dependent diabetic patients. Comparison of two different patient education regimens.

Eighty consecutive newly diagnosed non-insulin-dependent diabetic patients were randomly allocated into two groups to compare two different patient education regimens. One group received individual dietary instructions by a nurse and the other a short, written leaflet given by a doctor. The principal aim of the dietary instructions was weight reduction. A significant weight loss and improvement in the control of diabetes occurred in both groups, and these changes were similar in the two groups. At the end of one year's follow-up, however, only 25% of the patients were satisfactorily controlled (fasting blood glucose less than or equal to 6.0 mmol/l). The degree of weight loss correlated only weakly with the improvement in the metabolic control. The degree of obesity and insulin secretion capacity as measured at the beginning of the study did not predict the improvement of glycaemic control during the study. At the end of the study a significant improvement was observed in serum lipids of patients with good control (fasting blood glucose less than or equal to 6.0 mmol/l) or weight loss (greater than 5 kg). In conclusion, both brief, written and individual dietary instructions induced a significant weight loss as well as improved glucose and lipid metabolism in newly diagnosed non-insulin-dependent diabetic patients, but satisfactory metabolic control was achieved only in a minority of the patients.

Blood Glucose↗
PubMed1987

Molecular cloning of the Escherichia coli O75X adhesin.

The uropathogenic strain Escherichia coli IH11128 (O75:K5:H-) exhibits a mannose-resistant O75X adhesin. The genes encoding the O75X adhesin were cloned from a clinical strain and transferred to E. coli K-12 derivatives. The recombinant plasmids were found to express a 15-kilodalton fimbrial subunit protein, a fimbrialike extracellular structure, and mannose-resistant hemagglutination. An indirect immunofluorescence assay was used to study attachment of the clone and purified adhesin to frozen sections of human kidney. The clone bound selectively to the interstitial areas and notably to Bowman's capsule. The purified adhesin bound to the basement membrane of the tubules and to Bowman's capsule.

Adhesins, Escherichia coli↗
PubMed1986

Identification of the O-linked sialyloligosaccharides of glycophorin A as the erythrocyte receptors for S-fimbriated Escherichia coli.

The erythrocyte receptors for S-fimbriated Escherichia coli, which causes sepsis and meningitis in newborn infants, were investigated. Neuraminidase and trypsin treatments of erythrocytes abolished the hemagglutination ability of the bacteria. To identify the receptor glycoproteins, we separated erythrocyte membrane proteins by gel electrophoresis, blotted them to nitrocellulose, and incubated them with 125I-labeled bacteria. The only bacterium-binding bands identified corresponded to glycophorin A dimer and monomer, and the binding was abolished by neuraminidase treatment of the blot. Radiolabeled bacteria also bound to purified glycophorin A adsorbed to polyvinyl chloride microwells, and the binding was inhibited by other sialoglycoproteins and isolated sialyloligosaccharides containing the NeuAc alpha 2-3Gal sequence. Oligosaccharides which contain the NeuAc alpha 2-3Gal beta 1-3GalNAc and NeuAc alpha 2-3Gal beta 1-3(NeuAc alpha 2-6)GalNAc sequence and which are identical to the O-linked saccharides of glycophorin A were twofold more effective inhibitors of binding than were other oligosaccharides containing the NeuAc alpha 2-3Gal sequence. The replacement of sialic acid in asialoerythrocytes with a purified Gal beta 1-3GalNAc alpha 2-3 sialyltransferase, which forms the O-linked NeuAc alpha 2-3Gal beta 1-3GalNAc sequence in asialoglycophorins, restored bacterial hemagglutination. These results indicated that the major erythrocyte receptor for S-fimbriated E. coli is the NeuAc alpha 2-3Gal beta 1-3GalNAc sequence of the O-linked oligosaccharide chains of glycophorin A.

Bacterial Adhesion↗