Search PubMed⌕ Search

Biomedical subjects

C Larsson

Publications and source records attributed to C Larsson.

At least 91 records · Page 5Linked to original sources

An abundant TIP expressed in mature highly vacuolated cells.

Aquaporins are water channel proteins found in vacuolar membranes and plasma membranes, and belong to the major intrinsic protein (MIP) family of proteins. In the present study, we purified a 75 kDa MIP protein from a crude fraction of spinach leaf intracellular membranes. Upon urea/SDS-PAGE, the 75 kDa protein appeared as a 21 kDa polypeptide, and the 75 kDa species therefore probably represents a tetramer. The corresponding cDNA was obtained by PCR cloning and had an open reading frame encoding a 25.1 kDa protein. The protein, So-deltaTIP, was most homologous to the tonoplast intrinsic protein (TIP) subfamily of plant MIPs. Using affinity-purified So-deltaTIP-specific peptide antibodies, we investigated the subcellular and tissue distribution of So-deltaTIP. So-deltaTIP was specifically located in the vacuolar membrane. It was abundant in most vacuolated cells in all vegetative organs, but was excluded from the leaf epidermis as well as from the root phloem parenchyma and meristem. In spite of the high sequence homology between delta-TIPs of spinach, Arabidopsis, sunflower and radish, their expression patterns were totally different. However, a comparison of the expression pattern of So-deltaTIP with that of more distantly related TIPs showed similarities with Arabidopsis gamma-TIP, which is expressed in zones of cell elongation/differentiation but excluded from meristematic tissues. Meristematic cells are characterized by many small vacuoles as opposed to elongating and mature cells, which generally harbour a single, large vacuole. Our results indicate that the expression of So-deltaTIP may be induced when the large vacuole is formed.

Amino Acid Sequence↗

Comparative genomic hybridization reveals population-based genetic alterations in hepatoblastomas.

Hepatoblastoma is a malignant paediatric liver tumour. In order to approach the genetic background of this malignancy we have screened a panel of eighteen cases from Europe and Japan for chromosomal imbalances using comparative genomic hybridization (CGH). The most frequent losses included chromosomal regions 13q21-q22 (28%) and 9p22-pter (22%), while the most frequent gains occurred on 2q23-q24 (33%), 20q (28%) and 1q24-q25 (28%). A significant difference in CGH alterations between the tumours from patients of Caucasian and Japanese was revealed where loss of 13q was found only in the Japanese samples. In conclusion, the findings indicate several candidate regions for suppressor genes and oncogenes potentially involved in the hepatoblastomas of different ethnic origin.

Adolescent↗

Hydroxyapatite granule/carrier composites promote new bone formation in cortical defects.

BACKGROUND: A great deal of interest has been focused on finding substitutes for autogenous bone grafts. Among the most interesting materials are different calcium phosphate compositions (e.g., hydroxyapatite [HA]), due to their biocompatible properties in hard and soft tissue. PURPOSE: The bone response to porous ceramic HA granules in combination with two lipid and one polysaccharide carrier was evaluated in an experimental bone defect model in rabbits. MATERIALS AND METHODS: Circular defects (Ø 4 mm) were made in both tibias of 32 rabbits. The 64 defects were divided into four groups. Group A was augmented with a composite of HA granules and a phospholipid-diacetyl-glycerol carrier, group B with HA granules and a phospholipid carrier, group C received HA granules and a sodium hyaluronan carrier, and group D served as control. The animals were killed after 6 weeks and ground sections were evaluated using light microscopic morphometry. X-ray microfluorescence (XRF) was applied in order to evaluate the suitability of this method to examine bone-biomaterial interfaces. Calcium distribution was studied using x-ray fluorescence line scans at selected interface regions of two sections in group B. RESULTS: The HA/phospholipid composites were easier to shape and handle than the HA/hyaluronan composite. Group A had 36% newly formed bone area within the defect. Groups B and C showed significantly more newly formed bone within the defect (47% and 49%, respectively) compared to the control group (31%). The XRF analysis revealed that the amount of calcium in the newly formed bone was similar to that observed for the HA granules and slightly lower when compared to the mature, lamellar bone. CONCLUSIONS: Synchrotron radiation may be a new, suitable technique to study the interface between bone and biomaterials with regard to mineral content. The results suggest that HA granule/lipid and HA granule/hyaluronan composites have interesting properties as bone-substitute materials.

Animals↗

Familial isolated hyperparathyroidism as a variant of multiple endocrine neoplasia type 1 in a large Danish pedigree.

We report here our genetic findings of a family in which 14 members were affected with isolated primary hyperparathyroidism. Hyperparathyroidism is the main feature of multiple endocrine neoplasia type 1 (MEN1), making the recently cloned MEN1 gene a prime candidate gene in this family. Significantly positive lod scores were achieved with D11S4946 (3.36) and D11S4940 (3.53), and by combining the results from these two markers, a maximum positive lod score of 4.12 at recombination fraction 0.00 was obtained. Mutation analysis of MEN1 performed by full sequencing identified a missense mutation in exon 4, causing an amino acid change from glutamine to proline at codon 260. This mutation (Q260P) was present in all affected family members, and the inheritance of the mutation was in complete agreement with the disease-associated haplotype. In comparison with the recent functional studies of the menin protein interactions, this mutation is located in a region with little or no binding activity to JunD and activating protein-1 transcription factor. We conclude that some of the familial isolated primary hyperparathyroidism families constitute a milder variant of MEN 1, which is associated with a functionally milder missense mutation.

Adult↗

A genotypic and histopathological study of a large Dutch kindred with hyperparathyroidism-jaw tumor syndrome.

Familial primary hyperparathyroidism is the main feature of 2 familial endocrine neoplasia syndromes: multiple endocrine neoplasia type 1 (MEN 1) and hyperparathyroidism-jaw tumor syndrome (HPT-JT). The latter is a recently described syndrome that has been associated with ossifying fibroma of the jaw and various types of renal lesions, including benign cysts, Wilms' tumor, and hamartomas. To further illustrate the natural history of this syndrome, we describe a large, previously unreported Dutch kindred in which 13 affected members presented with either parathyroid adenoma or carcinoma; in 5 affected individuals, cystic kidney disease was found. Additionally, pancreatic adenocarcinoma, renal cortical adenoma, papillary renal cell carcinoma, testicular mixed germ cell tumor with major seminoma component, and Hürthle cell thyroid adenoma were also identified. Linkage analysis of the family using MEN1-linked microsatellite markers and mutation analysis excluded the involvement of the MEN1 gene. Using markers from the HPT-JT region in 1q2531, cosegregation with the disease was found, with a maximum logarithm of odds score of 2.41 obtained for 6 markers using the most conservative calculation. Meiotic telomeric recombination between D1S413 and D1S477 was identified in 3 affected individuals, and when combined with previous reports, delineated the HPT-JT region to 14 centimorgan. Combined comparative genomic hybridization and loss of heterozygosity data revealed complex genetic abnormalities in the tumors, suggesting different possible genetic mechanisms for the disease. In conclusion, we report a family with hyperparathyroidism linked to chromosome 1q, and exhibiting several types of renal and endocrine tumors that have not been previously described.

Chromosome Mapping↗

Expression of RET and its ligand complexes, GDNF/GFRalpha-1 and NTN/GFRalpha-2, in medullary thyroid carcinomas.

OBJECTIVE: Mutations in the RET proto-oncogene are found in about one third of sporadic medullary thyroid carcinomas (MTCs), mostly affecting codon 918. Glial cell line derived neurotropic factor (GDNF) and its membrane-bound GDNF family receptor alpha (GFRalpha-1), as well as neurturin (NTN) and its membrane-bound receptor GFRalpha-2 form a complex with the RET product, a receptor tyrosine kinase, resulting in downstream signaling to the nucleus. DESIGN: To elucidate the role of these RET ligands in MTC tumorigenesis, their expression was determined in 15 MTC samples, one papillary thyroid carcinoma (PTC) and three normal thyroid tissue specimens. METHODS: The mRNA expression of RET, GDNF, GFRalpha-1, NTN and GFRalpha-2 was investigated by mRNA in situ hybridization, and confirmed by reverse transcription-PCR analysis. RESULTS: None of the five genes was expressed in the normal thyroids or in the PTC. All MTCs showed expression of RET, 13 expressed GDNF, 12 expressed GFRalpha-1 and 9 expressed NTN and GFRalpha-2. In 7 of the tumors RET, GDNF and GFRalpha-1 were expressed at high levels, and in five of these seven tumors NTN and GFRalpha-2 genes were also expressed at high levels. The high level of expression was preferentially seen in tumor cells adjacent to stroma and connective tissue. All MTCs without expression of the RET ligands harbored the RET codon 918 mutation. CONCLUSIONS: The results suggest that this signaling pathway is important for MTC development, and that it may be activated by expression of the RET ligand complexes by the tumor cells themselves.

Adult↗

Linkage analysis of candidate regions in Swedish nonsyndromic cleft lip with or without cleft palate families.

OBJECTIVE: To analyze linkage of five candidate regions for nonsyndromic cleft lip with or without palate (CLP) on chromosome 2p13, 4q, 6p23, and 19q13; in addition chromosome 1q32, the locus for van der Woude syndrome, on Swedish CLP families. DESIGN: Three to five linked microsatellite markers were selected from each candidate region. Polymerase chain reaction (PCR) with fluorescent-labeled microsatellite markers was performed on DNA samples from the participating families. Electrophoresis of the PCR products was performed on a laser-fluorescent DNA sequencer. The genotype data were analyzed with multipoint linkage analysis. Modes of inheritance tested included two autosomal dominant, an autosomal recessive, and a nonparametric model. Multipoint logarithm of odds (LOD) scores were also calculated by assuming genetic heterogeneity. PARTICIPANTS: Nineteen Swedish multigenerational families with at least two first-degree relatives affected with CLP. Greater than 50% of the families studied show vertical transmission of the clefting phenotype and both inter- and intrafamilial variability were noted. RESULTS: Cumulative multipoint LOD scores for the whole group of families calculated under autosomal dominant modes of inheritance were negative in all regions and less than -2 except chromosome 6p23. LOD scores calculated under recessive inheritance and the nonparametric model were inconclusive. There was no significant evidence of genetic heterogeneity among the sample group. CONCLUSIONS: The group of Swedish CLP families did not demonstrate significant linkage to any of the five candidate regions examined. This might suggest a new but yet unknown CLP locus or loci in this family group. However, because linkage could not be excluded in some individual families, they should still be tested with candidate genes from these regions.

Chromosome Mapping↗

Modulating IGFBP-3 expression by trichostatin A: potential therapeutic role in the treatment of hepatocellular carcinoma.

The Hep3B cell line analyzed in the present study is a widely used in vitro model in studies characterizing pathogenetic, functional, and therapeutic aspects of human hepatocellular carcinoma (HCC). Here we have determined the chromosomal composition using a combination of cytogenetic techniques. In agreement with the original description for this cell line, Hep3B was found to have a hypotriploid chromosome content carrying 59-63 chromosomes and no cytogenetic differences were demonstrated between early and late passages suggesting that this cell line has remained stable after repeated subculturing. Mutations and alterations of the IGF-axis as well as of chromosome 1p34, where the genes for histone deacetylase 1 (HDAC1) and transforming growth factor beta receptor interacting protein-1 (TRIP-1) map, are frequent events in hepatocarcinogenesis. This study characterizes the Hep3B cell line in detail at the karyotypic level, using comparative genomic hybridization (CGH), spectral karyotyping (SKY), G-banding and FISH techniques. We have also examined the effects of the histone deacetylase inhibitor trichostatin A (TSA) on members of the IGF-axis, and analysed them with regard to the karyotype. The results show that expression of one member of the IGF-axis, IGFBP-3, is greatly upregulated by treatment of Hep3B cells with TSA. As IGFBP-3 has been shown to induce apoptosis, these results suggest a possible use for histone deacetylase inhibitors and/or IGFBP-3 in the treatment of HCC.

Carcinoma, Hepatocellular↗

Spectral karyotyping and chromosome banding studies of primary breast carcinomas and their lymph node metastases.

Three primary breast tumors and their lymph node metastases were characterized by G-banding, spectral karyotyping (SKY), and fluorescence in situ hybridization (FISH). In each case, the karyotypic abnormalities detected were similar in the primary tumor and its matched metastasis. Two of the pairs had near-diploid karyotypes with three to four chromosomal aberrations, whereas the third pair had a near-pentaploid chromosome content and many marker chromosomes in the primary tumor and a near-tetraploid chromosome number with almost the same marker chromosomes in the metastasis. SKY and FISH confirmed the karyotypic similarities between the primary tumors and their metastases and, in addition, improved the identification and characterization of marker chromosomes. One of the tumor pairs with near-diploid karyotypes had gain of 8q, 16q, and 17q, whereas the other had gain of 1q and chromosome 8 material in the form of ring chromosomes. The third pair had more complex chromosomal translocations and numerical changes resulting in net gain of material from chromosomes X, 1, 2, 6, 7, 14, 16, 19, and 20, and chromosome arms 8q and 11q, as well as net loss of material from chromosomes 3, 13, 18, 21, and 22. The present study underscores the need to combine conventional chromosome banding and molecular cytogenetic techniques in the cytogenetic analysis of solid tumors.

Breast Neoplasms↗

New chromosomal breakpoints in non-Hodgkin's lymphomas revealed by spectral karyotyping and G-banding.

Chromosomal rearrangements in short term cultures from nine cases of non-Hodgkin's lymphomas (NHL) were characterized by G-banding, spectral karyotyping (SKY), and fluorescence in situ hybridization (FISH). Eight of the nine cases showed complex karyotypes with chromosomal aberrations which, in most cases, could not be fully characterized by traditional G-banding analysis alone. Karyotypic abnormalities of special interest were marker chromosomes and chromosomes with added unidentified chromosomal material, as previously non-identified chromosomal translocations were hidden behind these aberrations. SKY and FISH analysis, as a complement to banding analysis, significantly improved the karyotypes in seven of the nine cases and unveiled 21 previously unidentified rearrangements with novel translocation breakpoints. Traditional G-banding alone revealed seven new rearrangements, which were all confirmed by SKY. None of these new aberrations occurred as single clonal rearrangements but as parts of complex karyotypes. Nevertheless, the chromosomal break-point regions identified should be considered as potential hot spots for genes involved in the tumorigenesis of the malignancy.

Adult↗

Characterization of the human peroxisome proliferator activated receptor delta gene and its expression.

Peroxisome proliferator activated receptors (PPARs) are nuclear receptors regulating the expression of genes involved in lipid and glucose metabolism. Three different PPARs; alpha (PPARA), gamma (PPARG) and delta (PPARD) have been characterized and they are distinguished from each other by tissue distribution and cell activation. In this study, the structure and detailed chromosomal localization of the human PPARD gene was determined. Three genomic clones containing the PPARD gene was isolated from a human P1 library. The gene spans approximately 85 kb of DNA and consists of 9 exons and 8 introns with exons ranging in size from 84 bp to 2.3 kb and introns ranging from 180 bp to 50 kb. All splice acceptor and donor sites conform to the consensus sequences including the AG-GT motif. Although PPARD lacks a TATA box, the gene is transcribed from a unique start site located 380 bp upstream of the ATG initiation codon. The 5' and 3' ends were mapped by rapid amplification of cDNA ends and the mRNA size of PPARD based upon the structure of the gene is 3803 bp. In addition, the chromosomal sublocalization of PPARD was determined by radiation hybrid mapping. The PPARD gene is located at 14 cR from the colipase gene and 15 cR from the serine kinase gene at chromosomal region 6p21.2.

Adult↗

Expression analysis of RET and the GDNF/GFRalpha-1 and NTN/GFRalpha-2 ligand complexes in pheochromocytomas and paragangliomas.

Pheochromocytoma and its extra-adrenal counterpart paraganglioma are rare catecholamine producing tumors which usually occur sporadically but may also be a part of neuroendocrine tumor syndromes such as multiple endocrine neoplasia type 2A (MEN 2A). Activating mutations of the RET proto-oncogene which is the underlying cause of MEN 2A, is also seen in approximately 10% of sporadic pheochromocytomas. Glial cell line derived neurotrophic factor (GDNF) and neurturin (NTN) have been shown to function as independent ligands to RET, binding in a complex with the membrane-bound receptors GFRalpha-1 and GFRalpha-2 respectively. Here we have investigated the mRNA expression of RET and its ligand complexes, GDNF/GFRalpha-1 and NTN/GFRalpha-2, in a panel of pheochromocytomas and paragangliomas using mRNA in situ hybridization. RET expression was evident in normal adrenal medulla, and in 13/15 pheochromocytomas, including 5/5 MEN 2A associated tumors, but only in 1/10 paragangliomas. The frequent expression of RET in the pheochromocytomas suggest that this gene might be involved in the tumorigenesis. However, no expression of GDNF/GFRalpha-1 or NTN/GFRalpha-2 could be detected in any of the 25 tumors analyzed, suggesting that these ligand complexes are not important in the development of pheochromocytoma or paraganglioma.

Adolescent↗

Expression of genes involved with cell cycle control, cell growth and chromatin modification are altered in hepatoblastomas.

Hepatoblastoma is a rare pediatric liver tumor. While much progress has been made in the treatment of the disease, very little is known about the moleculer events underlying the pathogenesis of this disease. We sought to investigate a series of hepatoblastomas for alterations in gene expression patterns with emphasis on important cell regulatory genes, including chromatin modifying enzymes, cyclin dependent kinase inhibitors, growth factors, oncogenes and cell cycle regulators. Total RNA was extracted from a series of sporadic hepatoblastomas with matched normal liver, some unmatched tumors and fetal livers, and gene expression was measured for various genes using RNase Protection Analysis (RPA). The results of this analysis show that the expression of many important regulatory genes are distinctly altered in these tumors, and a subset of tumors can be distinguished on the basis of these gene expression differences and histopathological features. Because the molecular events underlying the pathogenesis of this rare tumor are so poorly understood, this study represents a first step in determining some of the possible mechanisms involved which may provide future avenues of research.

Case-Control Studies↗

Protein kinase C beta1 is implicated in the regulation of neuroblastoma cell growth and proliferation.

To investigate a putative involvement of protein kinase C (PKC) isoforms in supporting neuroblastoma cell proliferation, SK-N-BE(2) neuroblastoma cells were transfected with expression vectors coding for the C2 and V5 regions from different PKC isoforms. These structures have been suggested to inhibit the activity of their corresponding PKC isoform. The PKC fragments were fused to enhanced green fluorescent protein to facilitate the detection of transfected cells. Expression of the C2 domain from a classical PKC isoform (PKCalpha), but not of C2 domains from novel PKCdelta or PKCepsilon, suppressed the number of neuroblastoma cells positive for cyclin A and bromodeoxyuridine incorporation. This indicates a role for a classical isoform in regulating proliferation of these cells. Among the V5 fragments from PKCalpha, PKCbetaI, and PKCbetaII, the PKCbetaI V5 had the most suppressive effect on proliferation markers, and this fragment also displaced PKCbetaI from the nucleus. Furthermore, a PKCbeta-specific inhibitor, LY379196, suppressed the phorbol ester- and serum-supported growth of neuroblastoma cells. There was a marked enhancement by LY379196 of the growth-suppressive and/or cytotoxic effects of paclitaxel and vincristine. These results indicate that PKCbetaI has a positive effect on the growth and proliferation of neuroblastoma cells and demonstrate that inhibition of PKCbeta may be used to enhance the effect of microtubule-interacting anticancer agents on neuroblastoma cells.

Antineoplastic Agents, Phytogenic↗

Salinity and hyperosmotic stress induce rapid increases in phosphatidylinositol 4,5-bisphosphate, diacylglycerol pyrophosphate, and phosphatidylcholine in Arabidopsis thaliana cells.

In animal cells, phosphoinositides are key components of the inositol 1,4,5-trisphosphate/diacylglycerol-based signaling pathway, but also have many other cellular functions. These lipids are also believed to fulfill similar functions in plant cells, although many details concerning the components of a plant phosphoinositide system, and their regulation are still missing. Only recently have the different phosphoinositide isomers been unambiguously identified in plant cells. Another problem that hinders the study of the function of phosphoinositides and their derivatives, as well as the regulation of their metabolism, in plant cells is the need for a homogenous, easily obtainable material, from which the extraction and purification of phospholipids is relatively easy and quantitatively reproducible. We present here a thorough characterization of the phospholipids purified from [(32)P]orthophosphate- and myo-[2-(3)H]inositol-radiolabeled Arabidopsis thaliana suspension-cultured cells. We then show that NaCl treatment induces dramatic increases in the levels of phosphatidylinositol 4,5-bisphosphate and diacylglycerol pyrophosphate and also affects the turnover of phosphatidylcholine. The increase in phosphatidylinositol 4,5-bisphosphate was also observed with a non-ionic hyperosmotic shock. In contrast, the increase in diacylglycerol pyrophosphate and the turnover of phosphatidylcholine were relatively specific to salt treatments as only minor changes in the metabolism of these two phospholipids were detected when the cells were treated with sorbitol instead of NaCl.

Arabidopsis↗

Mapping of autosomal dominant progressive external ophthalmoplegia to a 7-cM critical region on 10q24.

OBJECTIVE: To map the gene responsible for autosomal dominant progressive external opthalmoplegia. BACKGROUND: The pathogenesis of progressive external ophthalmoplegia (PEO) can be associated with multiple deletions of mitochondrial DNA (mtDNA). PEO may show autosomal dominant (adPEO) or autosomal recessive (arPEO) patterns of inheritance, indicating that the genetic defect has a Mendelian basis and most likely involves a nuclear gene encoding a protein that interacts with the mitochondrial genome. adPEO is heterogeneous genetically, and thus far disease loci have been identified on chromosomes 3 and 10. The locus on chromosome 10q23-q25 was assigned by linkage analysis in a single Finnish family. METHODS: Samples from a large Pakistani family with adPEO, in which clinical symptoms are bilateral ptosis, limitations of eye movements, and varying degrees of proximal muscle weakness, were collected. Muscle biopsy and mtDNA rearrangement analysis was used to confirm the diagnosis. Genomewide linkage analysis was set up using a set of 391 microsatellite markers. RESULTS: The muscle biopsy from an affected member showed ragged red fibers, increased succinic dehydrogenase staining, lack of cytochrome oxidase activity, and multiple deletions of mtDNA. The disease locus was mapped to 10q23.31-q25.1 by linkage analysis, and a maximum lod score of 5.72 was obtained with D10S1267. CONCLUSION: By analysis of meiotic recombinations in affected individuals, the critical region was restricted to the 7-cM interval between D10S198 and D10S1795.

Adult↗

Effects of bis(4-chlorophenyl) sulfone on rats following 28-day dietary exposure.

The short-term oral toxicity of a recently identified environmental pollutant, bis(4-chlorophenyl) sulfone (BCPS), was studied. Groups of male Sprague-Dawley rats (n = 6) were administered BCPS via the diet at 0 (control), 10, 100, or 1000 ppm for 4 wk. Additional control and 1000 ppm groups were also treated for 1, 2, and 3 wk. At termination, high-dose animals showed depressed growth rate and food consumption, and 1 high dose animal in each of the wk-1, -3, and -4 groups had marked hematuria. Increased liver to body weight ratio was present at 100 ppm and increased kidney to body weight ratio at 1000 ppm. Marked increases in hepatic benzoylresorufin O-dealkylase (BROD) and pentoxyresorufin O-dealkylase (PROD) activities were detected starting at 10 ppm. There was a significant decrease in methoxyresorufin O-dealkylase (MROD) activity at 1000 ppm. Hepatic UDP-glucuronosyltransferase (UDPGT) and glutathione S-transferase (GST) activities also increased starting at 100 ppm. A marked increase in urinary excretion of ascorbic acid was apparent starting at 10 ppm, while there were no changes in urinary N-acetylglucosaminidase (NAG) activity and protein levels. A threefold increase in serum cholesterol and a 30% increase in platelet counts were observed in the 1000 ppm group. Levels of thiobarbituric acid-reactive substances (TBARS) were increased by threefold in the liver of the high-dose animals but were not significantly altered in the serum. Tissue BCPS concentrations were dose dependent and followed the order: adipose tissue >>> liver > kidneys > brain, spleen, lungs. In the time-course study involving the control and high-dose groups, most of the treatment effects were clearly present in wk 1, and the severity of the effects remained at more or less the same levels thereafter. The exceptions were hepatic BROD and PROD activities, which showed a trend toward further increases with time of treatment. Liver and adipose tissue concentrations of BCPS remained unchanged from wk 1 to wk 4, while kidney concentrations increased with time. The results indicated that BCPS produced hepatic effects at the lowest dose level tested (10 ppm in the diet or 0.8 mg/kg/d).

Administration, Oral↗