Biomedical subjects

J Vilkki

Publications and source records attributed to J Vilkki.

At least 55 records · Page 3Linked to original sources

PubMed1990

Analysis of mitochondrial ND4 gene DNA sequence in Finnish families with Leber hereditary optic neuroretinopathy.

A mutation in the mitochondrial DNA at nt 11,778 has recently been found in Leber hereditary optic neuroretinopathy (LHON), a maternally inherited ocular disease. The mutation is located in the ND4 gene encoding subunit 4 of the respiratory chain enzyme NADH dehydrogenase. The mutation was subsequently not found in 9 of the 20 known Finnish families with LHON, implying that there are at least two different mutations associated with the disease. Using direct sequencing of PCR-amplified mtDNA, we have now sequenced the entire ND4 region in the families without the nt 11,778 mutation to find the other mutations. No new mutations in the ND4 region were found, suggesting that the putative mtDNA mutation in these families may be in the coding regions for other subunits of NADH dehydrogenase enzyme. The sequence of ND4 gene as found to be highly homogeneous.

Animals↗

PubMed1990

Social outcome related to cognitive performance and computed tomographic findings after surgery for a ruptured intracranial aneurysm.

A series of 83 patients was examined with a battery of cognitive tests, a clinical interview, and computed tomography 1 year after surgery for a ruptured intracranial aneurysm. Disability on the Glasgow Outcome Scale (33%), failure to return to work (25%), impaired social relations (25%), and subjective or clinical mental impairment (56%) were found to be related to each other and to poor performance on cognitive tests, especially to verbal impairments in patients with left lateral infarctions and to memory deficits and cognitive inflexibility in patients with frontal medial infarctions. Furthermore, cognitive deficits and poor outcome were associated with diffuse brain damage. Depression and anxiety were unrelated to test performances, but were frequently reported by patients with right lateral infarctions.

Adult↗

PubMed1990

Segregation of mitochondrial genomes in a heteroplasmic lineage with Leber hereditary optic neuroretinopathy.

Relatively little is known about the factors maintaining mitochondrial DNA (mtDNA) sequence diversity in humans. A detailed understanding of the transmission genetics of mtDNA has been partly hampered by the lack of evidence for heteroplasmic individuals. Among families with Leber hereditary optic neuroretinopathy, we found a maternal lineage with individuals heteroplasmic for a single nucleotide change, and we were able to follow the segregation of polymorphic mitochondrial genomes over 3 generations. The results show that rapid segregation can occur but also that the level of heteroplasmy can be maintained from one generation to another. In this family the disease phenotype is associated with the mtDNA sequence change, confirming the involvement of the mutation in the disease.

Base Sequence↗

PubMed1989

Mitochondrial DNA polymorphism in Finnish families with Leber's hereditary optic neuroretinopathy.

Leukocyte mitochondrial DNA (mtDNA) from 17 Finnish families with Leber's hereditary optic neuroretinopathy and 70 maternally unrelated controls as well as skeletal muscle mtDNA from four of the Leber families and three controls was analyzed with 30 restriction enzymes. By this means, over 10% of the nucleotides of mtDNA were screened. No major deletion or insertion was found in any of the mtDNAs studied. The restriction fragment patterns of mtDNA showed no evidence of mtDNA heteroplasmy (mixture of different mtDNA types) in either blood or muscle cells. In all, 24 mtDNA types were observed in the material. In the maternal lines of Leber families, 11 mtDNA types were found, indicating no recent common maternal ancestor for the Finnish Leber families. In spite of several previously unknown polymorphisms, no mutation of mtDNA could be found exclusively in families with Leber's disease. However, a couple of mutations leading to amino acid replacements of mitochondrially encoded proteins were observed in certain Leber families only. These mutations have occurred in genes coding for subunits of NADH dehydrogenase, suggesting that a defect of the respiratory chain complex I may cause Leber's disease.

DNA, Mitochondrial↗

PubMed1989

Deficient programming in spatial learning after frontal lobe damage.

Patients with anterior or posterior brain damage and control subjects performed a spatial sequence learning task in which the score obtained depended on the subject's ability to set sub-goals appropriate for his learning capacity. The anterior group obtained lower scores and more frequently set inadequate sub-goals than the posterior group. No anterior vs posterior difference was found on a similar learning task in which another sequence was learnt by predetermined sub-goals. The result supported the hypothesis that frontal lobe lesions disturb programming or goal-based search for action structure on spatial learning.

Adult↗

PubMed1989

Perseveration in memory for figures after frontal lobe lesion.

The aim was to determine whether recurrent perseveration, i.e. the tendency to incorrectly repeat previous responses, is related to the site of cerebral lesion. Sixty-seven brain-damaged patients and 35 control subjects were studied with a modified Benton Visual Retention Test. Patients with anterior lesions made a higher number of recurrent perseverations than patients with posterior lesions. The results was in disagreement with the hypothesis that recurrent perseveration is associated with left posterior lesions.

Adult↗

PubMed1989

Differential perseverations in verbal retrieval related to anterior and posterior left hemisphere lesions.

Sixty-two patients with focal cerebral lesions and 11 control patients were examined using alternating tasks of learning, generation, and recall of words beginning with "K." The results supported the hypothesis that "recurrent" and "stuck-in-set" varieties of perserveration are related to posterior and anterior left hemisphere lesions, respectively. Patients with left posterior lesions usually failed to suppress the expression of previously generated words in the subsequent generation task, whereas patients with left anterior lesions stated a greater number of new (incorrect) words in the recall of previously learned words, presumed to indicate stuck-in-set perseveration of the previous generation performance.

Adult↗

PubMed1989

Speed-accuracy optimization in acquisition of figures after focal cerebral lesion.

Seventy-seven brain damaged patients and 14 control subjects performed a visual memory test in which the subjects had to reproduce geometric figures from memory after studying the design for 10 seconds (standard condition) and after an observation period subjectively necessary and sufficient for accurate reproduction (self-timed condition). The brain damaged patients were less efficient than the control subjects on the self-timed acquisition even when the covariance on the standard condition was taken into account. The prediction that frontal lobe damaged patients are inferior to posterior brain damaged patients on the speed-accuracy optimization of acquisition was true only in the right hemisphere damaged patients on the simple trials, suggesting that right frontal lobe damage disturbs voluntary attention. Visuospatial errors were typical for right hemisphere damaged patients, perservations for left frontal lobe damaged patients.

Adult↗

PubMed1989

Hemi-inattention in visual search for parallel lines after focal cerebral lesions.

Visual search and line orientation discrimination was studied in 67 brain-damaged and 15 control subjects, with the aim of demonstrating that hemi-inattention follows both left- and right-hemisphere damage even when confined to the frontal lobe. Both anterior and posterior lesions of either hemisphere caused inattention to the side contralateral to the lesion, this asymmetry being pronounced at the onset of search, especially in patients with anterior lesions. Hemi-inattention was associated with the overall inefficiency of line orientation discrimination and exploration as well as simple verbal performance in right-hemisphere-damaged patients, but tended to dissociate from these deficits in left hemisphere-damaged patients. Brain-damaged patients were inferior to the control subjects, and women inferior to men in the overall efficiency of exploration, but only women with right posterior lesions had a deficit in line orientation discrimination.

Attention↗

PubMed1989

Cognitive deficits related to computed tomographic findings after surgery for a ruptured intracranial aneurysm.

A consecutive series of 118 patients operated on for ruptured intracranial arterial aneurysms was studied. Ninety-six of them could be adequately examined with a battery of psychological tests and computed tomographic scans 1 year after a subarachnoid hemorrhage. Seventeen orthopedic control patients with no history of brain damage were also tested. The pattern of cognitive deficits was strongly related to the findings on the computed tomographic scans. Patients with left lateral infarctions had deficits on performances requiring verbal efficiency, including memory and classification tasks, whereas patients who had right lateral infarctions were poor on a visuoconstructional task (the copying of Rey's Figure). These deficits were pronounced when lateral infarction was associated with diffuse brain damage. Patients with frontal medial infarctions had low scores on memory tests; the inefficiency in verbal fluency, categorical reasoning, and memory was related to diffuse brain damage. The patients who had no infarctions did not differ significantly from the control group. Cognitive impairments after left lateral and frontal medial infarctions, as well as diffuse brain damage, correlated with the Glasgow Outcome Scale.

Brain↗

PubMed1989

Genetic heterogeneity in Leber hereditary optic neuroretinopathy revealed by mitochondrial DNA polymorphism.

The presence or absence of a recently observed mitochondrial DNA (mtDNA) mutation associated with Leber hereditary optic neuroretinopathy (LHON) was tested in 19 Finnish families with cases of LHON. Leukocyte and muscle DNA from individuals with optic atrophy, microangiopathy, or normal fundi from maternal lineages were studied by Southern blot analysis, using mouse mtDNA as a hybridization probe. The mtDNA mutation, detected as SfaNI site polymorphism, was seen in 10 of the 19 families. In one family, the mutation was seen only in the two affected individuals, indicating recent origin for the mutation. Nine families and 28 maternally unrelated controls did not show the mutation. The results imply that alternative mtDNA mutations are associated with LHON and that this genetic heterogeneity may be the cause of the interfamilial variation in the clinical expression of LHON. In the families showing the SfaNI site mutation, the mutation was homoplasmic in all individuals irrespective of their disease status, suggesting that the intrafamilial variation in the clinical expression is not due to different ratios of mutant versus normal mtDNA.

Blotting, Southern↗

PubMed1988

Human mitochondrial DNA types in Finland.

Variation in mitochondrial DNA (mtDNA) in a sample of 110 Finns was analyzed with six restriction enzymes, AvaII, BamHI, HaeII, HindII, HpaI, and MspI, by using total blood cell DNA probed with mouse mtDNA. Two new enzyme morphs were observed, one for HaeII and one for HindII. Double-digestion experiments indicated that the BamHI morphs 2 and 3 result from base changes leading to AvaII morphs 3 and 9, respectively. Of the ten different mtDNA types observed, defined by restriction fragment patterns, seven have been previously described in Caucasoid populations. The three new "Finnish" mtDNA types can be derived from Caucasoid lineages by single restriction site changes. The results were used to reconstruct a phylogenetic tree for Caucasoid mtDNA types defined by the enzymes used. The frequencies of mtDNA types were used to compute genetic distances between Finns, Italians, and Israeli Jews. The frequencies of both enzyme morphs and mtDNA types show that the Finnish population is highly homogeneous.

DNA Restriction Enzymes↗

PubMed1988

Problem solving deficits after focal cerebral lesions.

Verbal comprehension and naming, identification of categories, as well as problem solving on reasoning and sorting tasks were examined in 57 patients with focal brain lesions and 20 control patients. The results confirmed the prediction that frontal lobe lesions cause a more pronounced deficit in problem solving than posterior lesions. However, patients with left frontal lobe lesions showed verbal inefficiency which possibly disturbed their sorting on the basis of feedback, but the inferiority of the frontal lobe damaged patients on category identification was not secondary to this verbal deficit. As the patients with left posterior lesions did not have marked verbal deficits, the present findings should be confined to patients lacking severe aphasia, which may also disturb problem solving in patients with posterior lesions.

Adult↗

PubMed1988

Memory disorder related to coma duration after head injury.

The relationship of memory and intelligence test performances to coma duration was studied in 51 head injured patients who had not been operated on for intracranial haematoma. Memory defect was related to coma duration, and was not secondary to impaired perceptual or conceptual analysis of the material to be remembered.

Adult↗

PubMed1987

Incidental and deliberate memory for words and faces after focal cerebral lesions.

It was predicted that right-hemisphere lesions cause a more marked deficit of shallow incidental memory than deep incidental or deliberate memory, the degree of the deficits being reversed after left-hemisphere lesions. This hypothesis was studied by measuring memory for words and faces in brain-damaged patients and nine controls after: shallow incidental learning, i.e. detecting words containing the letter 'A' and counting male and female faces; deep incidental learning, i.e. detecting words that mean man-made things and searching for well-known faces; and deliberate learning of words and faces. The results failed to support the hypothesis, but were consistent with the well-established finding that left- and right-hemisphere lesions disturb memory for words and faces, respectively.

Adult↗

PubMed1987

Ideation and memory in the inkblot technique after focal cerebral lesions.

The aim was to study whether an inkblot technique can reveal differential deficits of ideation and memory related to the side and site of brain damage. Seventy-three patients with focal brain lesions and nine control patients were studied with a modified Holtzman Inkblot Technique. The results confirmed the previous Rorschach test finding that left-hemisphere-damaged patients have poor ideational productivity, whereas right-hemisphere-damaged patients have a perceptual disturbance indicated by a high number of diffuse color responses to whole blots. Furthermore, the patients with anterior lesions were inferior to the patients with posterior lesions in perceptual integration and in memory for inkblots. Deficient verbal recall was linked to left-hemisphere lesions, poor recognition and preserved verbal recall being associated with right-hemisphere lesions. The inkblot perception findings specific to the side and site of the brain lesion were unrelated to conventional intelligence test scores.

Adult↗

PubMed1985

Amnesic syndromes after surgery of anterior communicating artery aneurysms.

Five patients had severe generalized disorder of memory, which lasted for several months after anterior communicating artery aneurysm surgery. Two of them had no signs of frontal lobe lesions. They were confused for not more than four days after surgery. One of them performed normally on the non-memory tests and short-term memory tests. Cues did not substantially improve his poor memory performance. The other patient had similar test results, but he had poor imagination in an inkblot perception test. Three patients had frontal lobe lesions. Two of them were restless, confused and confabulating, with one showing apathetic and stereotyped behaviour for more than a month after surgery. On the memory tests they showed disinhibition of irrelevant associations or deficient initiative. Cueing markedly improved their poor retrieval. These defects seem to be associated with frontal lobe lesions and can affect memory but are not obligatory features of amnesia.

Adult↗

PubMed1984

Visual hemi-inattention after ventrolateral thalamotomy.

Ten patients undergoing left ventrolateral thalamotomy (LVLT) and 11 patients undergoing right ventrolateral thalamotomy (RVLT) for Parkinsonian or essential tremor performed a test of visual searching for parallel lines before and after surgery. On average RVLT caused impairment of searching only on the left side. LVLT affected searching on both sides, with the impairment being slightly more marked on the right side, The tendency to initiate searching from the side ipsilateral to the lesion increased after VLT. The results indicated that unilateral VLT caused hemi-inattention in visual searching, which deficit is possibly related to the transient motor neglect usually observed in the extremities contralateral to VLT.

Adult↗