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L Haataja

Publications and source records attributed to L Haataja.

At least 37 records · Page 2Linked to original sources
PubMed1999

Neonatal neurological examination in infants with hypoxic ischaemic encephalopathy: correlation with MRI findings.

Neurological examination and magnetic resonance imaging were performed in the neonatal period in 58 full-term infants who presented with hypoxic-ischaemic encephalopathy. The aim of this study was to evaluate the patterns of neurological abnormalities and their correlation to brain lesions on MRI. The prognostic value of the neurological examination performed at different times in the neonatal period was also evaluated. Our results showed that specific clinical patterns can be observed in infants with HIE and these can be related to the pattern of lesion on brain MRI. In particular, while infants with normal MRI or minimal changes tend to show only minor tone abnormalities after the first week of life, infants with more severe lesions such as basal ganglia lesions show persistent and diffuse neurological abnormalities. Infants with white matter changes but intact basal ganglia show a different clinical pattern with improved sucking reflex and behaviour and less severe tone abnormalities. Our results also suggested that the neurological examination performed after the second week of life is a reliable indicator of outcome in these infants.

Asphyxia Neonatorum↗
PubMed1999

Visual function in term infants with hypoxic-ischaemic insults: correlation with neurodevelopment at 2 years of age.

AIMS: To determine if there is any association between the findings of visual assessment performed at the age of 5 months and neurodevelopmental outcome at the age of 2 years in children who have sustained hypoxic-ischaemic insults. METHODS: Twenty nine term infants with hypoxic-ischaemic encephalopathy and/or brain lesions on neonatal magnetic resonance imaging (MRI) were prospectively evaluated. At 5 months of age all the infants had their visual function assessed using the Atkinson Battery of Child Development for Examining Functional Vision, which includes the assessments of optokinetic nystagmus (OKN), acuity, visual fields, fixation shift and phase and orientation reversal visual evoked potentials. At 2 years of age the children had a structured neurological evaluation and a Griffiths developmental assessment. RESULTS: There was good correlation between the extent of the early detected visual impairment and both neuromotor and global development. Children with more than three out of five abnormal visual tests at 5 months of age tended to have abnormal neurological examination results and abnormal developmental quotients. Children with three or fewer abnormalities tended to have developmental quotients in the normal range; the level of their performance, however, was still related to the number of visual tests passed. CONCLUSIONS: Individual visual tests can provide important prognostic information. While abnormal OKN and acuity were always associated with abnormal outcome, normal results on visual evoked potentials and fixation shift tended to be associated with normal outcome.

Brain↗
PubMed1999

Increased brain glucose utilization in Salla disease (free sialic acid storage disorder).

UNLABELLED: Salla disease is an autosomal recessive lysosomal free sialic acid storage disorder characterized by psychomotor retardation and ataxia. MRI studies have revealed evidence of dysmyelination, but the biological mechanism of the brain dysfunction is unknown. METHODS: Nine patients with Salla disease (age 2.5 mo-42 y) presenting the disease in varying degrees of severity were studied by PET using 2-fluoro-2-deoxy-D-glucose (FDG) as a tracer. Local cerebral metabolic rates for glucose (LCMRGlc) in individual brain regions were compared with controls. RESULTS: The FDG PET results showed significantly increased LCMRGlc values in the frontal and sensorimotor cortex and especially in the basal ganglia of the patients. Cerebellar hypometabolism was present in all seven patients with marked ataxia, whereas the less severely affected patients without obvious ataxia had normal or even high glucose uptake in the cerebellum. CONCLUSION: The increased cerebral glucose utilization is a constant finding in Salla disease and may reflect the basic defect of the sialic acid metabolism in this disorder. The FDG PET findings in the cerebellum suggest a correlation between glucose uptake and the severity of the clinical symptoms.

Adolescent↗
PubMed1998

Identification of a novel Rac3-interacting protein C1D.

Rac3 is a small GTPase of the Rho family, members of which have been implicated in tumorigenesis, cell growth/death and organization of the actin cytoskeleton. Many Rac-interacting proteins or effectors identified to date have a role in cytoskeletal organization. Using the yeast two-hybrid system, we have isolated a novel Rac3-interacting protein from a human placenta cDNA library which has no homology to other previously identified Rac-interacting proteins. Sequence analysis revealed that this protein is C1D, the human homolog of the murine SUN-CoR protein which acts as a corepressor for the thyroid hormone receptor. In yeast cells, C1D binds to constitutively activated but not to GDP-bound Rac3. When coexpressed with Rac3 in COS cells, C1D complexed with constitutively active Rac3 but not with wild-type Rac3, demonstrating that C1D-Rac3 interactions take place in vivo in mammalian cells and that C1D appears to be an effector of Rac3. The C1D gene was mapped to human chromosome 2, which frequently shows deletions in human follicular thyroid carcinomas.

Amino Acid Sequence↗
PubMed1997

BCR/ABL-induced leukemogenesis causes phosphorylation of Hef1 and its association with Crkl.

BCR/ABL is considered responsible for the development of Philadelphia chromosome-positive leukemia. Experimental animal models, such as transgenic mice, have demonstrated unambiguously that Bcr/Abl is capable of inducing leukemogenesis. The adaptor molecule Crkl is a major in vivo substrate of the deregulated Bcr/Abl tyrosine kinase and functions as a molecular link with other signaling proteins. While associated in vivo with Bcr/Abl through its SH3 domain, Crkl can interact simultaneously via its SH2 domain with other tyrosine-phosphorylated proteins. Here we report the identification of prominently tyrosine-phosphorylated proteins with a molecular mass of approximately 110 kDa, which bind specifically to the Crkl SH2 domain in leukemic tissues of P190BCR/ABL transgenic mice. We demonstrate that these proteins are identical to Hef1/Cas-L, which is related to p130(Cas). The proto-oncoprotein p120(Cbl) and Hef1, but not p130(Cas), were detectably phosphorylated on tyrosine in P190Bcr/Abl-expressing leukemic cells and were found in complex with Crkl, showing the existence of protein complexes in P190Bcr/Abl leukemic cells, consisting of P190Bcr/Abl, Crkl, and Hef1 or p120(Cbl). This supports a model in which Crkl acts as mediator between Bcr/Abl and downstream effectors. Since Hef1 is involved in the beta1-integrin signaling pathway, our study demonstrates that Bcr/Abl could specifically interfere with normal beta1-integrin signaling.

Adaptor Proteins, Signal Transducing↗
PubMed1997

Characterization of RAC3, a novel member of the Rho family.

The small GTP-binding proteins Rac1 and Rac2 are critically important in regulating multiple signal transduction pathways in eukaryotic cells. Here we report the isolation of a novel third Rac family member, Rac3. Rac3 differs from Rac1/2 at its carboxyl-terminal end, a domain associated with subcellular localization and binding to specific cellular regulators. RAC3 mRNA expression patterns differ from those of RAC2, which is hematopoietic specific and also from those of RAC1. The RAC3 gene was mapped to chromosome 17q23-25, a region frequently deleted in breast cancer. Rac3 protein levels are not affected by organization of the actin cytoskeleton but remarkably, are serum-inducible. Rac3 is an active GTPase, and this activity is regulated by Bcr. When constitutively activated, Rac3 is able to stimulate efficiently the c-Jun amino-terminal kinase signaling pathway. These findings support a role for Rac3 in intracellular signaling.

Amino Acid Sequence↗
PubMed1997

Deletion within the D17S34 locus in a primitive neuroectodermal tumor.

Loss of heterozygosity on chromosome 17p13.3 is frequently observed in solid tumors, and the presence of a tumor suppressor gene has been predicted in this region of chromosome 17. We have analyzed a primitive neuroectodermal tumor sample exhibiting loss of heterozygosity at the D17S34 locus, a commonly used telomeric marker on the short arm of chromosome 17. The remaining allele showed a rearrangement. Cosmids spanning the D17S34 locus and probes from that region were used to demonstrate a 9-kb deletion within the D17S34 locus and were found to contain evolutionary, conserved sequences. Genetic alterations in this region may also affect expression of immediately adjacent genes, such as ABR, and could be a common mechanism in the causation of primitive neuroectodermal tumors.

Chromosomes, Human, Pair 17↗
PubMed1996

Inhibition of Bcr serine kinase by tyrosine phosphorylation.

The first exon of the BCR gene encodes a new serine/threonine protein kinase. Abnormal fusion of the BCR and ABL genes, resulting from the formation of the Philadelphia chromosome (Ph), is the hallmark of Ph-positive leukemia. We have previously demonstrated that the Bcr protein is tyrosine phosphorylated within first-exon sequences by the Bcr-Abl oncoprotein. Here we report that in addition to tyrose 177 (Y-177), Y-360 and Y283 are phosphorylated in Bcr-Abl proteins in vitro. Moreover, Bcr tyrosine 360 is phosphorylated in vivo within both Bcr-Abl and Bcr. Bcr mutant Y177F had a greatly reduced ability to transphosphorylate casein and histone H1, whereas Bcr mutants Y177F and Y283F had wild-type activities. In contrast, the Y360F mutation had little effect on Bcr's autophosphorylation activity. Tyrosine-phosphorylated Bcr, phosphorylated in vitro by Bcr-Abl, was greatly inhibited in its serine/threonine kinase activity, impairing both auto- and transkinase activities of Bcr. Similarly, the isolation of Bcr from cells expressing Bcr-Abl under conditions that preserve phosphotyrosine residues also reduced Bcr's kinase activity. These results indicate that tyrosine 360 of Bcr is critical for the transphosphorylation activity of Bcr and that in Ph-positive leukemia, Bcr serine/threonine kinase activity is seriously impaired.

Animals↗
PubMed1995

Tyrosine phosphorylation of murine Crkl.

The SH2/SH3 adaptor protein Crkl is abnormally phosphorylated on tyrosine by the Bcr/Abl protein in leukemic cells from patients with Philadelphia-chromosome (Ph)positive leukemia. However, the state of tyrosine-phosphorylation of crkl in normal tissues is unknown. In the current study, we identified mouse crkl by cDNA cloning and examined expression levels and tyrosine-phosphorylation of the mouse crkl protein during embryogenesis and in adult tissues. Tyrosine-phosphorylation of crkl was prominent during early development, but decreased at later embryonic stages and in newborn mice. Expression of both crkl and the related crk was ubiquitous in the adult. However, crkl differed considerably from crk in relative tissue distribution, and was more abundant in hematopoietic tissues. With exception of the lung, crkl was mostly present in a non-tyrosine phosphorylated form. Consistent with our previous findings in human patients, murine crkl was phosphorylated on tyrosine in leukemic tissues of BCR/ABL transgenic animals, but was non-tyrosine phosphorylated in normal mouse bone marrow. We conclude that this crkl tyrosine-phosphorylation by Bcr/Abl in hematopoietic cells is clearly aberrant and is consistently linked to the development of leukemia. Identification of proteins interacting with tyrosine-phosphorylated crkl in the leukemic cells of BCR/ABL transgenic mice should reveal members of signal transduction pathways activated in Ph-positive leukemia.

Adaptor Proteins, Signal Transducing↗
PubMed1995

Altered enzyme activities of xenobiotic biotransformation in kidneys after subchronic administration of 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX) to rats.

Activities of the xenobiotic metabolizing enzymes were measured in the liver, kidney, duodenum and lung microsomes and cytosol fractions of Wistar rats after subchronic administration of 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX), a potent bacterial mutagen in chlorinated drinking water. MX was administered by gavage at the dose level of 30 mg/kg for 18 weeks (low dose), or at the dose level which was raised gradually from 45 mg/kg for 7 weeks via 60 mg/kg for 2 weeks to a clearly toxic dose of 75 mg/kg for 5 weeks (high dose). Microsomal and cytosolic preparations were made and the activities of 7-ethoxyresorufin-O-deethylase (EROD), pentoxyresorufin-O-dealkylase (PROD), NADPH-cytochrome-c-reductase, UDP-glucuronosyltransferase (UDPGT) and glutathione-S-transferase (GST) were measured. Kidneys were affected most. A dose-dependent decrease was observed in EROD (90% in males, 80% in females at the high dose) and in PROD (58% in females at the high dose) in kidneys. An increase was, however, detected in kidney NADPH-cytochrome-c-reductase (66% in females at high dose), UDPGT (89% in males and 97% in females at high dose) and GST activities (56% in males and 50% in females at high dose). MX caused only a few changes in the enzyme activities of the liver. The EROD activity was decreased 25% to 37%, both in the livers of males and females, but the total content of P450s was not altered. Hepatic GST activity was elevated in females in a dose-dependent manner (31% and 44%). GST activity was elevated in duodenum in females (59%) at the high dose. There were no marked changes in the enzyme activities in the lungs. MX was a weak inhibitor of EROD activity both in the liver and kidney microsomes in vitro, decreasing the EROD activity by 53% and 43%, respectively at the concentration of 0.9 mM. The results indicate that MX decreases the activity of phase I metabolism enzymes, but induces phase II conjugation enzyme activities, particularly in kidneys in vivo. It is possible that these changes contribute to metabolism of MX in kidneys and renders them susceptible to MX in the course of repeated exposure.

Administration, Oral↗
PubMed1995

Linkage disequilibrium utilized to establish a refined genetic position of the Salla disease locus on 6q14-q15.

Salla disease (SD), an inherited free sialic acid storage disorder, is caused by impaired transport of free sialic acid across the lysosomal membrane. Clinical characteristics of the disease include severe psychomotor retardation and some neurological abnormalities. We report here detailed linkage analyses of 50 Finnish SD families that localize the SD disease gene to a refined chromosomal area on 6q14-q15. The highest lod score of 17.30 was obtained with a microsatellite marker of locus D6S280. When linkage disequilibrium was adopted in the linkage analyses, we could further assign the SD locus to the immediate vicinity of marker locus D6S406. Linkage disequilibrium facilitated further restriction of the critical chromosomal region to approximately 80 kb, well within the limits of positional cloning techniques.

Alleles↗
PubMed1995

Spatial organization of ABR and CRK genes on human chromosome band 17p13.3.

Deletion of part or all of chromosome 17p is among the most frequent chromosome abnormalities in human cancer. We show that the CRK and ABR genes are close to a marker on chromosome 17p13.3, D17S34, which is frequently deleted in different tumours, and demonstrate that CRK is centromeric to ABR. CRK and ABR may be involved in cancer themselves, or otherwise may function as points of reference for further experiments to clone genes from chromosome 17p which may play a role in cancer.

Chromosome Banding↗
PubMed1994

Cellular interactions of CRKL, and SH2-SH3 adaptor protein.

Chronic myelogenous leukemia is characterized by a specific chromosomal translocation, t(9;22), in which the ABL protooncogene and the BCR gene become juxtaposed. The chimeric BCR/ABL gene produces a P210 fusion protein with deregulated tyrosine kinase activity. We have recently isolated a complementary DNA, CRKL, which could code for an adaptor protein consisting of one SH2 and two SH3 domains and lacking any catalytic domain. In the current study, we show that CRKL is highly phosphorylated in the chronic myelogenous leukemia cell line K562 and that it is a substrate for the p210 BCR/ABL and p145 ABL kinases. BCR/ABL and ABL are coimmunoprecipitated with CRKL in vivo, demonstrating that relatively stable complexes are formed. In addition, the nucleotide exchange factor mSOS1 was found to be coimmunoprecipitated with CRKL. These findings establish a putative signal transduction pathway way through which BCR/ABL mediates its oncogenic activity.

Adaptor Proteins, Signal Transducing↗
PubMed1994

Phenotypic variation and magnetic resonance imaging (MRI) in Salla disease, a free sialic acid storage disorder.

Salla disease (SD) is a recessively inherited lysosomal storage disorder particularly common in the Finnish population. Patients with SD are normal at birth, but develop psychomotor delay and ataxia during the first year of life. Phenotypic variation of SD is wide, ranging from severely disabled children to mentally retarded adults capable of living under sheltered conditions. In the present study four unusually severely affected patients were investigated by detailed clinical examination, magnetic resonance imaging (MRI) and analysis of the excretion of free sialic acid in urine. MRI study, reported here for the first time, revealed a similarly defective myelination pattern in seven patients. The myelination process seemed to cessate at the level of an infant of a few months of age. Genetic linkage study of the families of the severely affected patients suggested linkage to the recently discovered SD locus on the long arm of chromosome 6. Locus heterogeneity therefore is an unlikely explanation of the phenotypic variation in SD.

Adolescent↗
PubMed1994

The genetic locus for free sialic acid storage disease maps to the long arm of chromosome 6.

Salla disease (SD), or adult-type free sialic acid storage disease, is an autosomal recessive lysosomal storage disorder characterized by impaired transport of free sialic acid across the lysosomal membrane and severe psychomotor retardation. Random linkage analysis of a sample of 27 Finnish families allowed us to localize the SD locus to the long arm of chromosome 6. The highest lod score of 8.95 was obtained with a microsatellite marker of locus D6S286 at theta = .00. Evidence for linkage disequilibrium was observed between the SD locus and the alleles of three closely linked markers, suggesting that the length of the critical region for the SD locus is in the order of 190 kb.

Alleles↗
PubMed1993

Mutation in type II procollagen (COL2A1) that substitutes aspartate for glycine alpha 1-67 and that causes cataracts and retinal detachment: evidence for molecular heterogeneity in the Wagner syndrome and the Stickler syndrome (arthro-ophthalmopathy)

A search for mutations in the gene for type II procollagen (COL2A1) was carried out in affected members of a family with early-onset cataracts, lattice degeneration of the retina, and retinal detachment. They had no symptoms suggestive of involvement of nonocular tissues, as is typically found in the Stickler syndrome. The COL2A1 gene was amplified with PCR, and the products were analyzed by denaturing gradient gel electrophoresis. The results suggested a mutation in one allele for exon 10. Sequencing of the fragment demonstrated a single-base mutation that converted the codon for glycine at position alpha 1-67 to aspartate. The mutation was found in three affected members of the family available for study but not in unaffected members or 100 unrelated individuals. Comparison with previously reported mutations suggested that mutations introducing premature termination codons in the COL2A1 gene are a frequent cause of the Stickler syndrome, but mutations in the COL2A1 gene that replace glycine codons with codons for bulkier amino acid can produce a broad spectrum of disorders that range from lethal chondrodysplasias to a syndrome involving only ocular tissues, similar to the syndrome in the family originally described by Wagner in 1938.

Adolescent↗