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Biomedical subjects

J Vilkki

Publications and source records attributed to J Vilkki.

At least 37 records · Page 2Linked to original sources
PubMed1998

Evaluation of genetic variability and genetic distances between eight chicken lines using microsatellite markers.

The genetic variability and divergence of eight chicken lines were evaluated using nine microsatellite markers. The chicken lines included three White Leghorn hybrids, three Finnish Landrace lines, a Rhode Island Red line, and a broiler hybrid line. All the microsatellite loci were found to be polymorphic, the number of alleles varying from 4 to 13 per locus and 1 to 10 per line, respectively. Observed heterozygosities ranged from 0.00 to 0.91. The highest (0.67) and lowest (0.29) mean heterozygosity per line was observed in the broiler and in White Leghorn of Mäkelä, respectively. Three of the microsatellite loci deviated from the Hardy-Weinberg equilibrium in some populations. F statistics indicated clearly the subdivision of the total population into different lines. The genetic distances confirmed the classification of Finnish Landraces into different lines. A phylogenetic consensus tree was constructed from resampled data (1,000 times) using the neighbor-joining method. According to the phylogenetic tree, the lines were grouped into three clusters, in which the White Leghorns formed one group, two Landraces a second group, and a Landrace, the Rhode Island Red, and the broiler lines a third group. Allele distribution at the loci does not support either the stepwise or the infinite alleles mutation model, but the distribution pattern was quite irregular at different loci.

Animals↗
PubMed1998

Neuropsychological correlates of duration of glances at secondary tasks while driving.

The aim of this study was to find out the neuropsychological measures correlating with overlong glances at secondary in-car tasks while driving. Fifteen. patients with brain damage (without clear neurological or neuropsychological restriction on driving a car) and 11 healthy participants drove a route of 126 km and performed a series of secondary tasks while driving on a highway in an instrumented compact car. Four videocameras allowed detailed analysis of glances during in-car tasks. Neuropsychological measures focused on executive functions, memory, visuospatial skills, and fine motor skills. Moreover, patients' emotional self-evaluation and relatives' evaluation of patients' competencies were included. The proportion of overlong glances away from the road during in-car tasks was greater among the patients than. the healthy drivers. The long glances of the patients correlated strongly with motor and visuospatial deficits, cognitive inflexibility, emotional symptoms, and relatives' evaluations of patients' impaired sensomotor abilities. The results suggest that the frequency of overlong glances was increased by 2 factors: (a) impaired motor and visuospatial skills that evidently caused difficulties in the manipulation of the equipment of the secondary tasks, and (b) impairments of executive functions that were likely to decrease the ability to control the risks related to long glances at the in-car tasks. The slowing of speed during secondary tasks was on the average rather slight and not significantly more pronounced among patients than control drivers, indicating that patients failed to reduce their speed and thus the risk related to prolonged glances at in-car tasks.

Journal Article↗
PubMed1996

Frontal tests do not detect frontal infarctions after ruptured intracranial aneurysm.

The series of 155 patients operated on for a ruptured intracranial arterial aneurysm was examined using typical frontal tests (the Stroop test, word fluency tasks, and a sorting task), as well as a learning and memory test. Patients with frontal infarction were not significantly inferior to patients with non-frontal infarction or to patients with no infarction. Frontal patients, however, were unable to return to work as often as non-frontal patients and more frequently than those with no infarction. These results indicate that the frontal tests used in this study are not selectively sensitive to mainly medial frontal infarctions that follow the rupture of an anterior cerebral artery aneurysm.

Adult↗
PubMed1996

Dual task performance after focal cerebral lesions and closed head injuries.

The aim of this study was to demonstrate that focal frontal lobe lesions and closed head injuries cause a deficit in the deliberate minimizing of dual task decrements that follow when two separate tasks should be done concurrently. In single tasks, subjects counted backwards and cancelled visual targets as quickly and accurately as possible on separate 1 min trials. In the dual task, they were required to do both tasks simultaneously, taking care that performance on neither task would be notably more impaired than on the other, as only the performance showing a larger percentage decrement from the corresponding single task performance was taken into account as the result of the test. Patients with acute closed head injury displayed more pronounced dual task decrement than the controls. This deficit was not secondary to inefficiency on the single tasks but was related to the depth of coma at admission, the acuteness of injury and age. Contrary to expectation, patients with focal frontal lobe lesions or patients with subacute closed head injury did not demonstrate abnormal dual task decrement.

Adult↗
PubMed1996

Cognitive decline in patients with symptomatic HIV-1 infection. No decline in asymptomatic infection.

Thirty-six HIV-1-infected predominantly well-functioning subjects were followed up for one year by repeated neuropsychological, clinical neurological, neuroradiological, and immunological examinations. Changes in cognitive performance related to the severity of HIV-1 infection as well as to neuroradiological or immunological changes were studied. A decline in cognitive speed and flexibility was found in symptomatic subjects (ARC, AIDS). The impairment was especially pronounced in patients with progression of brain atrophy. These findings suggest a brain pathology underlying the cognitive decline in ambulatory outpatients with symptomatic HIV-1 infection. A practice effect was found in asymptomatic subjects (ASX, LAS) and in those with unchanged CT/MRI scans. No systematic relationship was found between cognitive change and immunological change.

Adult↗
PubMed1995

Random amplified polymorphic DNA in cattle and sheep: application for detecting genetic variation.

The present study investigated the use of the random amplified polymorphic DNA (RAPD) method to detect genetic variation in cattle and sheep. The animals studied consisted of samples from five Finnish cattle breeds: native Eastern (18 animals), Northern (24), Western Finncattle (24), Finnish Ayrshire (24), and Finnish Friesian (18); as well as a white (6 animals) and a grey (9) colour type of Finnsheep. The cattle and sheep populations were analysed with 11 and 13 RAPD primers demonstrating the most repeatable amplification pattern. Two out of ten RAPD fragments tested by cross hybridization showed homology between the two species. The RAPD method did not prove efficient for finding new polymorphisms in either species, because we found only three polymorphic RAPD markers for cattle and seven markers for sheep with different allele frequencies between the breeds. Although there is a greater presence of polymorphic RAPD markers in sheep, according to the similarity indices the sheep populations showed a higher degree of homogeneity than the cattle breeds. However, the interbreed and intrabreed similarity indices for cattle did not suggest any significant differentiation of the Finnish breeds, contrary to earlier results based on blood group and protein polymorphism.

Animals↗
PubMed1995

Casein haplotypes and their association with milk production traits in the Finnish Ayrshire cattle.

Polymorphism of casein genes was studied in half-sib families of artificial insemination bulls of the Finnish Ayrshire dairy breed. Ten grandsires and 300 of their sons were genotyped for the following polymorphisms: alpha s1-casein (B, C), beta-casein (A1, A2), the microsatellite within the kappa-casein gene (ms5, ms4) and kappa-casein (A, B, E). Nine different combinations of these alleles, casein haplotypes, were found. Associations between casein haplotypes and milk production traits (milk and protein yield, fat and protein percentage and milking speed) were studied with ordinary least-squares analysis to find a direct effect of the haplotypes or an association within individual grandsire families using the granddaughter design. Estimated breeding values of sons were obtained from cow evaluation by animal model. No direct effect of the casein haplotypes on the traits was found. Within grandsire families, in one out of four families the chromosomal segment characterized by haplotype 3 (B-A2-ms4-A) was associated with an increase in milk yield (P < 0.01) and a decrease in fat percentage (P < 0.01) when contrasted with haplotype 8 (B-A1-ms4-E). The results provide evidence that in the Finnish Ayrshire breed at least one quantitative trait locus affecting the genetic variation in yields traits is segregating linked to either haplotype 3 (B-A2-ms4-A) or 8 (B-A1-ms4-E).

Animals↗
PubMed1994

Speed and flexibility on word fluency tasks after focal brain lesions.

It was predicted that frontal lobe damaged patients are slower on word fluency tasks, especially on the generation of words beginning with a particular letter, and less flexible ("stuck-inset") on category alternation than patients with posterior lesions, whereas the latter commit a higher number of repetitions ("recurrent perseverations") than the former. Twenty-nine anterior and 31 posterior brain damaged patients were requested to say as quickly as possible (1) 20 animal names, (2) 10 words beginning with the letter S, and (3) alternately animals and S-words, 10 from each category without repeating the words already used in these tasks. The results failed to confirm the predictions.

Adult↗
PubMed1994

Prediction of psychosocial recovery after head injury with cognitive tests and neurobehavioral ratings.

A series of 53 patients was studied using a battery of tests and a neurobehavioral rating scale on average 4 months after closed-head injury (CHI). Social outcome was assessed 1 year after injury by interviewing a family member. The results supported the hypothesis that tests of flexibility and programming rather than tests of cognitive skills predict psychosocial recovery after CHI. Spatial Learning with Self-Set Goals and Sorting were measures of flexibility and programming. Contrary to expectation, word fluency performance was unrelated to these measures, but was associated with conventional intelligence tests, which did not predict psychosocial recovery. Cognition/Energy deficit on the Neurobehavioral Rating Scale and increased age were useful predictors of poor psychosocial outcome, whereas computed tomography findings or the Glasgow Coma Score were weakly related to the outcome indices. Evidently, cognitive flexibility and mental programming are very important psychological prerequisites of social recovery after CHI.

Adolescent↗
PubMed1992

Cognitive flexibility and mental programming after closed head injuries and anterior or posterior cerebral excisions.

Cognitive inflexibility and deficient mental programming are specifically related to frontal lobe lesions. The aim was to demonstrate that closed head injury (CHI) patients with brain lesions verified by computed tomography have such cognitive deficits, and are inferior in these respects to patients with posterior cerebral excisions mainly for tumours. This hypothesis was confirmed using a Category Identification and Sorting test as well as a measure of mental programming in a Spatial Learning task. Furthermore, CHI patients who had non-frontal parenchymal lesions were inferior by these measures to patients with posterior excisions. This result suggests that diffuse axonal lesion in CHI causes the deficits similar to those following frontal lobe excision.

Adolescent↗
PubMed1992

Cognitive test performances related to early and late computed tomography findings after closed-head injury.

Computed tomography (CT) findings from early (less than 24 hours) and late scan (6 months) after closed-head injury (CHI) were compared to cognitive test scores obtained on an average of 4 months after injury in a consecutive series of 53 patients. The presence of parenchymal lesion was associated with poor test results, indicating cognitive inflexibility and disinhibition of routine response tendencies in novel tasks. These deficits have previously been found to be related in particular to frontal-lobe dysfunction, but the present study did not support the hypothesis that frontal lesion is the principal cause of this impairment in CHI. Parenchymal lesions in the right and left hemisphere were associated with spatial and verbal deficits, respectively. Ventricular enlargement in the late CT was related to cognitive inefficiency, both being strongly associated with age. The results suggest that parenchymal lesion in the early CT is an indicator of diffuse axonal injury, which results in cognitive inflexibility during recovery.

Adolescent↗
PubMed1991

Mental programming after frontal lobe lesions: results on digit symbol performance with self-selected goals.

The aim of this study was to demonstrate that the inability to set adequate sub-goals in a cognitive task is a sensitive indicator of programming deficit after frontal lobe lesion. Sixty-one patients with focal cerebral lesions and 25 control subjects were studied with a modified Digit Symbol task, in which the score depended on the adequacy of the sub-goals set by the subject. This score was compared to that on the standard condition, in which the subject was requested to work as quickly as possible without self-selected goals. The results confirmed the prediction that patients with anterior lesions set less adequate sub-goals than patients with posterior lesions and, unlike the latter patients, have a more pronounced deficit on the performance with self-selected goals than on the standard condition. In particular patients with left frontal lobe lesions underestimated their capabilities in relation to task requirements.

Adult↗
PubMed1991

A new mtDNA mutation associated with Leber hereditary optic neuroretinopathy.

A single base mutation at nucleotide position 3460 (nt 3460) in the ND1 gene in human mtDNA was found to be associated with Leber hereditary optic neuroretinopathy (LHON). The G-to-A mutation converts an alanine to a threonine at the 52d codon of the gene. The mutation also abolishes an AhaII restriction site and thus can be detected easily by RFLP analysis. The mutation was found in three independent Finnish LHON families but in none of the 60 controls. None of the families with the nt 3460 mutation in ND1 had the previously reported nt 11778 mutation in the ND4 gene. The G-to-A change at nt 3460 is the second mutation so far detected in LHON.

Animals↗
PubMed1991

Optic atrophy in Leber hereditary optic neuroretinopathy is probably determined by an X-chromosomal gene closely linked to DXS7.

Leber hereditary optic neuroretinopathy (LHON) is a maternally inherited disease, probably transmitted by mutations in mtDNA. The variation in the clinical expression of the disease among family members has remained unexplained, but pedigree data suggest an involvement of an X-chromosomal factor. We have studied genetic linkage of the liability to develop optic atrophy to 15 polymorphic markers on the X chromosome in six pedigrees with LHON. The results show evidence of linkage to the locus DXS7 on the proximal Xp. Tight linkage to the other marker loci was excluded. Multipoint linkage analysis placed the liability locus at DXS7 with a maximum lod score (Zmax) of 2.48 at a recombination fraction (theta) of .0 and with a Zmax - 1 support interval theta = .09 distal to theta = .07 proximal of DXS7. No evidence of heterogeneity was found among different types of families, with or without a known mtDNA mutation associated with LHON.

Adult↗