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Biomedical subjects

L Andersson

Publications and source records attributed to L Andersson.

At least 127 records · Page 7Linked to original sources
PubMed1998

Amplification of ColE1 related plasmids in recombinant cultures of Escherichia coli after IPTG induction.

ColE1-derived plasmids containing different recombinant genes which are controlled by the tac promoter were amplified following induction with IPTG, but no amplification occurred if product formation was not induced. The plasmid copy number of recombinant E. coli increased three- to sixfold within a period of about 6 h in shake flask experiments, batch cultures, and glucose-limited fed-batch cultivations. Plasmid amplification occurred in E. coli B strains as well as in K-12 strains with different plasmids (rop+ and rop-) coding for various heterologous proteins. The amplification was not caused by a toxic effect of IPTG, but was related to a strong inhibition of translation and chromosomal replication after the induction of heterologous gene expression. Similar to the amplification after chloramphenicol addition, plasmid replication proceeded even if oriC replication and translation were inhibited following strong induction of a recombinant gene. In accordance with the effect of chloramphenicol, the level of ppGpp, which is a negative regulator of ColE1 derived plasmid replication, decreased after induction.

Bacterial Proteins↗
PubMed1998

Functional changes in scavenger receptor binding conformation are induced by charge mutants spanning the entire collagen domain.

Macrophage scavenger receptors are trimeric integral membrane proteins that bind a diverse array of negatively charged ligands. They have been shown to play a role in the pathogenesis of atherosclerosis and in host responses to microbial infections. Earlier mutational studies demonstrated that the distal segment of the collagen domain of the receptor was critically important for high affinity ligand binding activity. In this study, mutations spanning the entire collagen domain were generated and binding was assayed in transfected cells, as well as in assays employing a secreted, receptor fusion protein. Many of the distal, positively charged C-terminal residues in the type II collagen domain of the receptor, previously reported to be essential for binding at 37 degreesC, were found not to be critical for binding at 4 degreesC. Conversely, more proximally charged residues of the collagen receptor that have not been previously mutated were shown to have substantial effects on binding that were also temperature-dependent. These data suggest that scavenger receptor ligand recognition depends on more complex conformational interactions, involving charged residues throughout the entire collagen domain, than was previously recognized.

Amino Acid Sequence↗
PubMed1998

Mapping quantitative trait loci for immune capacity in the pig.

Immune capacity traits show considerable genetic variation in outbred populations. To identify quantitative trait loci (QTLs) for immune capacity in the pig, various measures of immune function (total and differential leukocyte counts, neutrophil phagocytosis, mitogen-induced proliferation, IL-2 production, and virus induced IFN-alpha production in whole blood cultures, and Ab responses to two Escherichia coli antigens) were determined in 200 F2 animals from a wild pig-Swedish Yorkshire intercross. The pedigree has been typed for 236 genetic markers covering all autosomes, the X chromosome and the X/Y pseudoautosomal region. Through interval mapping using a least-squares method, four QTLs with significant effects were identified; one for total leukocyte counts, one for mitogen-induced proliferation, one for prevaccination levels of Abs to E. coli Ag K88, and one for Ab response to the O149 Ag. In addition, several putative QTLs were indicated. The results from the present study conclusively show that it is possible to identify QTLs for immune capacity traits in outbred pig populations by genome analysis.

Animals↗
PubMed1998

Identification of a mutation in the low density lipoprotein receptor gene associated with recessive familial hypercholesterolemia in swine.

Elevated blood plasma cholesterol (hypercholesterolemia) is a major risk factor for coronary artery disease (CAD) in humans. Genetic dissection of polygenic lipid and lipoprotein disorders in swine, a key animal model for the study of familial hypercholesterolemia (FH) and CAD, led to the isolation of a monogenic subphenotype (FH-r), that is inherited in the recessive (r) manner. A genome scan mapped the FH-r locus close to the centromere of chromosome 2. Comparative mapping showed that this region shares homology with a part of human chromosome 19 that harbors the low density lipoprotein receptor (LDLR) locus, and therefore suggested LDLR as the prime candidate gene for FH-r. Cloning and sequencing of hepatic LDLR cDNA from two FH-r/r and one normal (N/N) animals disclosed a single missense mutation (R84C) in a region that corresponds to human exon 4. The C84 mutation cosegregates invariantly with hypercholesterolemia, which strongly suggests that this mutation is responsible for the observed hyperlipidemia.

Amino Acid Sequence↗
PubMed1998

The corn inhibitor of activated Hageman factor: purification and properties of two recombinant forms of the protein.

A cDNA clone that encodes the 14-kDa bifunctional inhibitor from corn seeds (L. Wen et al., Plant Mol. Biol. 18, 813-814, 1992) has been expressed in Escherichia coli after being incorporated into the pT7 expression vector. This inhibitor protein, referred to as CHFI (for the corn inhibitor of activated Hageman factor) or as the popcorn inhibitor, is an important tool for specific inhibition of human activated Hageman factor (activated forms of coagulation Factor XII) and has been well characterized as isolated from corn seeds. Recombinant CHFI was expressed in E. coli in high levels but was insoluble. We solubilized the expressed protein by sonication in 5 M urea and 1% Triton X-100. Several steps of purification, culminating with reversed-phase HPLC, yielded pure, recombinant corn inhibitor in about 5% yield (about 1 mg per liter of culture). The form with which we have worked most, 7N-CHFI, contains 7 amino acid residues at its N-terminus that are encoded by the expression vector. Physical properties of this recombinant protein indicate it has the expected mass and is properly folded. Functionally, 7N-CHFI is indistinguishable from the inhibitor isolated from corn seeds in its inhibition of porcine trypsin, human beta-Factor XIIa, failure to inhibit human plasma kallikrein, and its inhibition of an insect alpha-amylase. A second recombinant form, (4N-11)-CHFI, which lacks 11 residues from the corn inhibitor's N-terminus, is indistinguishable from 7N-CHFI in its pattern of inhibition of the three test proteinases but is inactive against the insect alpha-amylase. This suggests that the N-terminal region of 7N-CHFI forms at least part of the protein's site of interaction with alpha-amylase.

Base Sequence↗
PubMed1998

Physical ordering of six YACs from the RN region in pigs.

Six YAC clones representing five microsatellite markers from the RN region were mapped by fluorescent in situ hybridization (FISH) on pig metaphase chromosomes and their relative order was determined by pairwise multicolour FISH. Two of the microsatellites viz., Sw120 and Sw936 flank RN as well as the remaining three microsatellites Sw1683, Sw2083 and Sw1309. The results assigned the RN locus to the distal part of the 15q25 band. The linear order of the microsatellites was compared with the available linkage mapping data.

Animals↗
PubMed1998

Multiple marker mapping of quantitative trait loci in a cross between outbred wild boar and large white pigs.

A quantitative trait locus (QTL) analysis of growth and fatness data from a three generation pig experiment is presented. The population of 199 F2 animals was derived from a cross between wild boar and Large White pigs. Animals were typed for 240 markers spanning 23 Morgans of 18 autosomes and the X chromosome. A series of analyses are presented within a least squares framework. First, these identify chromosomes containing loci controlling trait variation and subsequently attempt to map QTLs to locations within chromosomes. This population gives evidence for a large QTL affecting back fat and another for abdominal fat segregating on chromosome 4. The best locations for these QTLs are within 4 cM of each other and, hence, this is likely to be a single QTL affecting both traits. The allele inherited from the wild boar causes an increase in fat deposition. A QTL for intestinal length was also located in the same region on chromosome 4 and could be the same QTL with pleiotropic effects. Significant effects, owing to multiple QTLs, for intestinal length were identified on chromosomes 3 and 5. A single QTL affecting growth rate to 30 kg was located on chromosome 13 such that the Large White allele increased early growth rate, another QTL on chromosome 10 affected growth rate from 30 to 70 kg and another on chromosome 4 affected growth rate to 70 kg.

Animals↗
PubMed1998

Melanocortin receptor 1 (MC1R) mutations and coat color in pigs.

The melanocortin receptor 1 (MC1R) plays a central role in regulation of eumelanin (black/brown) and phaeomelanin (red/yellow) synthesis within the mammalian melanocyte and is encoded by the classical Extension (E) coat color locus. Sequence analysis of MC1R from seven porcine breeds revealed a total of four allelic variants corresponding to five different E alleles. The European wild boar possessed a unique MC1R allele that we believe is required for the expression of a wild-type coat color. Two different MC1R alleles were associated with the dominant black color in pigs. MC1R*2 was found in European Large Black and Chinese Meishan pigs and exhibited two missense mutations compared with the wild-type sequence. Comparative data strongly suggest that one of these, L99P, may form a constitutively active receptor. MC1R*3 was associated with the black color in the Hampshire breed and involved a single missense mutation D121N. This same MC1R variant was also associated with EP, which results in black spots on a white or red background. Two different missense mutations were identified in recessive red (e/e) animals. One of these, A240T, occurs at a highly conserved position, making it a strong candidate for disruption of receptor function.

Alleles↗
PubMed1998

Psychological reactions during in-vitro fertilization: similar response pattern in husbands and wives.

The purpose of this study was to examine differences in daily emotional, physical and social reactions among husbands and wives during in-vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI). Forty couples about to undergo ICSI or IVF at a private infertility clinic monitored their emotional, physical and social reactions daily for one complete treatment cycle from the first day of stimulation until the outcome of treatment was known (approximately 35 days). The results showed that men and women had a similar response pattern to oocyte retrieval, fertilization, embryo transfer and the pregnancy test. These stages were associated with the most significant changes in reactions for both spouses. The pattern of results suggested that the most important psychological determinant of reactions during IVF was the uncertainty of treatment procedures. Spouses appeared to be equally sensitive to this uncertainty and both appeared to respond to it with ambivalent feelings involving emotional distress and positive feelings of hope and intimacy.

Adult↗
PubMed1998

Distress level in men undergoing intracytoplasmic sperm injection versus in-vitro fertilization.

The purpose of this study was to compare the psychological reactions of men undergoing intracytoplasmic sperm injection (ICSI) (n=18) or in-vitro fertilization (IVF) (n=22). Men monitored their psychological reactions daily for one complete treatment cycle from the first day of down-regulation until the outcome of treatment was known (approximately 52 days). The results showed that ICSI patients reported marginally more distress on the days prior to retrieval than the IVF patients. Other than this difference the pattern of results indicated that the psychological reactions of men undergoing ICSI or IVF were similar and that there was no need to manage these patients differently during treatment. However, ICSI patients may benefit from some reassuring comments on the days prior to retrieval when they showed more anticipatory anxiety.

Adult↗
PubMed1998

Xenoduplex analysis--a method for comparative gene mapping using hybrid panels.

Somatic cell hybrid (SCH) panels and radiation hybrid (RH) panels are powerful resources for comparative gene mapping because gene assignments are made without the detection of genetic polymorphism as needed for linkage mapping. A frequently encountered problem, however, is that the gene specific primers may amplify homologous PCR products of equal length from the donor and recipient species of the panel. Here, we describe a simple solution to this problem in which we utilize the formation of interspecies heteroduplexes that can be easily distinguished from the corresponding homoduplexes by native polyacrylamide gel electrophoresis. We denote these DNA-DNA interspecies hybrids, xenoduplexes (xeno = Gr. Xenos, foreigner). A merit of the method is that the formation of xenoduplexes strongly suggests that the PCR products from the two species represent homologous sequences. The method is thus particularly useful for comparative gene mapping when the PCR primers have been designed by use of sequence information from other species. In this study we have successfully used xenoduplex analysis and a pig-rodent SCH panel to map seven porcine genes (ACADM, AT3, HOXD, IL8RB, LEPR, PAX8, PKLR) for which no previous sequence information was available. The assignment of the leptin receptor gene (LEPR) to pig chromosome 6q32-35 excluded LEPR as a candidate gene for a QTL on pig chromosome 4 with a major effect on fatness.

Animals↗
PubMed1998

Molecular basis for the dominant white phenotype in the domestic pig.

The change of phenotypic traits in domestic animals and crops as a response to selective breeding mimics the much slower evolutionary change in natural populations. Here, we describe that the dominant white phenotype in domestic pigs is caused by two mutations in the KIT gene encoding the mast/stem cell growth factor receptor (MGF), one gene duplication associated with a partially dominant phenotype and a splice mutation in one of the copies leading to the fully dominant allele. The splice mutation is a G to A substitution in the first nucleotide of intron 17 and leads to skipping of exon 17. The duplication is most likely a regulatory mutation affecting KIT expression, whereas the splice mutation is expected to cause a receptor with impaired or absent tyrosine kinase activity. Immunocytochemistry showed that this variant form is expressed in 17- to 19-day-old pig embryos. Hundreds of millions of white pigs around the world are assumed to be heterozygous or homozygous for the two mutations. [The EMBL accession numbers for porcine KIT1*0101, KIT1*0202, KIT2*0202, and KIT2*0101 are AJ223228-AJ223231, respectively.]

Alternative Splicing↗
PubMed1998

Genomic approaches to the improvement of disease resistance in farm animals.

As a result of the difficulties in improving disease resistance in farm animals by traditional phenotype selection, the achievement of such improvement is one of the most important applications of genome research. The major hurdle to this important goal is the collection of informative disease records to enable the segregation of disease resistance loci (DRL) to be traced in pedigrees. This paper reviews the principles for DRL identification by association analyses or by linkage analyses. Once linkage has been established, the location of the DRL may be further refined, a process which may eventually lead to the molecular characterisation of the causative gene(s) and mutation(s). A reliable map assignment of a DRL is sufficient for the practical utilisation of this knowledge, since the inheritance of the DRL can be traced by flanking markers. Marker-assisted selection concerns the use of linked markers for selection within populations, while marker-assisted introgression is used if DRL alleles are introgressed from a donor (resource) population.

Animals↗
PubMed1998

Mapping quantitative trait loci for carcass and meat quality traits in a wild boar x Large White intercross.

An intercross between wild boar and a domestic Large White pig population was used to map quantitative trait loci (QTL) for body proportions, weight of internal organs, carcass composition, and meat quality. The results concerning growth traits and fat deposition traits have been reported elsewhere. In the present study, all 200 F2 animals, their parents, and their grandparents were genotyped for 236 markers. The marker genotypes were used to calculate the additive and dominance coefficients at fixed positions in the genome of each F2 animal, and the trait values were regressed onto these coefficients in intervals of 1 cM. In addition, the effect of proportion of wild boar alleles was tested for each chromosome. Significant QTL effects were found for percentage lean meat and percentage lean meat plus bone in various cuts, proportion of bone in relation to lean meat in ham, muscle area, and carcass length. The significant QTL were located on chromosomes 2, 3, 4, and 8. Each QTL explained 9 to 16% of the residual variance of the traits. Gene action for most QTL was largely additive. For meat quality traits, there were no QTL that reached the significance threshold. However, the average proportion of wild boar alleles across the genome had highly significant effects on reflectance and drip loss. The results show that there are several chromosome regions with a considerable effect on carcass traits in pigs.

Animals↗
PubMed1998

Mapping of serum amylase-1 and quantitative trait loci for milk production traits to cattle chromosome 4.

The present study was undertaken to confirm and refine the mapping of a quantitative trait locus in cattle for milk fat percentage that had earlier been reported to be linked to the serum amylase-1 locus, AM1. Five half-sib families from the previous study and 7 new ones were genotyped for nine microsatellite markers spanning chromosome 4. AM1 was mapped between the microsatellite markers BMS648 and BR6303. In a granddaughter design, interval mapping based on multiple-marker regression was utilized for an analysis of five milk production traits: milk yield, fat percentage and yield, and protein percentage and yield. In the families reported on previously, significant effects for fat and protein percentages were detected. In the new families, an effect on milk and fat yields was found. The most likely positions of the quantitative trait locus in both groups of families were in the same area of chromosome 4 in the vicinity of the obese locus. Direct effects of the obese locus were tested for using polymorphism in two closely linked microsatellites located 2.5 and 3.6 top downstream of the coding sequence. No firm evidence was found for an association between the obese locus and the tested traits.

Amylases↗
PubMed1998

Anterior-inferior mandibular osteotomy in treatment of obstructive sleep apnea syndrome.

In a prospective randomized study on treatment of obstructive sleep apnea syndrome, anterior-inferior mandibular osteotomy with the purpose of stretching the suprahyoidal muscle was performed as one of the treatment methods. Ten men aged 20 to 65 years, without cardiovascular or neurologic disease, with normal maxillomandibular relation, and having an apnea index between 5 and 25 were included in the study. After a specially designed osteotomy of the chin, the anterior suprahyoidal muscles were detached, stretched approximately 10 to 12 mm, and sutured. The chin was then placed in its original position and post-operative evaluation was performed. Although there were initial reports of decreased daytime sleepiness and less snoring after surgery, the results after 12 months were discouraging. Somnographic registration (apnea index, apnea/hypopnea index, and oxygen desaturation index) as well as cephalometric analysis failed to show positive results. Hence, suspension of the suprahyoidal muscles as a method of treatment for obstructive sleep apnea syndrome cannot be recommended.

Adult↗