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Biomedical subjects

C Kühn

Publications and source records attributed to C Kühn.

At least 19 recordsLinked to original sources

Severe obstructive calcifications affecting the descending and suprarenal abdominal aorta without coexisting peripheral atherosclerotic disease--coral reef aorta.

The case of a 58-year-old woman with leg claudication due to a very rare form of atherosclerosis affecting the descending thoracic and abdominal aorta--known as coral reef aorta--without involvement of the femoro-distal vessels is reported. The patient was treated with a polyester bifurcation graft from the proximal descending aorta to both common iliac arteries via a left dorsal mini-thoracotomy and a second left retroperitoneal approach. This unusual approach was chosen instead of direct aortic replacement in order to prevent paraplegia. In case of future visceral or left renal malperfusion the diseased artery can be connected to the prosthesis directly or by the use of an additional bypass graft. This would not be the case with a conventional axillo-bifemoral graft.

Anastomosis, Surgical↗

The PKA-CREB system encoded by the honeybee genome.

The cAMP-dependent kinase (PKA) plays a crucial part in long-term memory formation in the honeybee (Apis mellifera). One of the putative substrates of the PKA activity is the cAMP response element binding protein (CREB), a transcription factor in the bZIP protein family. We searched the honeybee genome to characterize genes from the CREB/CREM and the PKA families. We identified two genes that encode regulatory subunits and three genes encode catalytic subunits of PKA. Eight genes code for bZIP proteins, but only one gene was found that encodes a member of the CREB/CREM family. The phylogenetic relationship of these genes was analysed with their Drosophila and human counterparts.

Animals↗

Mapping of quantitative trait loci for lactation persistency traits in German Holstein dairy cattle.

A whole genome scan to map quantitative trait loci (QTL) for persistency of milk yield (PMY), persistency of fat yield (PFY), persistency of protein yield (PPY) and persistency of milk energy yield (PEY) was performed in a granddaughter design in the German Holstein dairy cattle population. The analysis included 16 paternal half-sib families with a total of 872 bulls. The analysis was carried out for the first lactation and for the first three lactations combined using univariate weighted multimarker regression. Controlling the false discovery rate across traits and data sets at a level of 0.15 and treating the four persistency traits as different traits revealed 27 significant QTL. A total of 12 chromosomes showed significant QTL effects on a chromosomewise basis. The DGAT1 effect was highly significant for PPY and protein yield. A haplotype analysis using results of previous studies of the same design revealed a co-segregation of various persistency QTL and QTL affecting health traits like dystocia and stillbirth and functional traits like non-return rate 90 and somatic cell score.

Animals↗

Characterization of the DGAT1 mutations and the CSN1S1 promoter in the German Angeln dairy cattle population.

The identification of quantitative trait loci (QTL) and genes with influence on milk production traits has been the objective of various mapping studies in the last decade. In the centromeric region of Bos taurus autosome (BTA) 14, the acyl-CoA:diacylglycerol acyltransferase1 gene (DGAT1) has been identified as the most likely causative gene underlying a QTL for milk fat yield and content. Recently, a second polymorphism in the promoter of DGAT1 emerged as an additional source of variation. In this study, the frequencies and the effects of alleles at the DGAT1 K232A and at the DGAT1 promoter variable number of tandem repeat (VNTR) locus on BTA14, and of alleles at the CSN1S1 (alpha(S1)-casein-encoding gene) promoter on BTA6 in the German Angeln dairy cattle population were investigated. Analyzed traits were milk, fat, protein, lactose, and milk energy yield, fat, protein, lactose, and milk energy content and somatic cell score. The lysine variant of the DGAT1 K232A mutation showed significant effects for most of the milk production traits. A specific allele of the DGAT1 promoter VNTR showed significant effects on the traits lactose yield and content, milk energy content, and SCS compared with the other alleles. Additionally, a regulation mechanism between the DGAT1 K232A mutation and the DGAT1 promoter VNTR was found for fat yield and content, which could be caused by an upper physiological bound for the effects of the DGAT1 gene. At the CSN1S1 promoter, 2 of 4 alleles showed significant allele substitution effects on the milk yield traits.

Alleles↗

DGAT1, a new positional and functional candidate gene for intramuscular fat deposition in cattle.

Intramuscular fat content, also assessed as marbling of meat, represents an important beef quality trait. Recent work has mapped a quantitative trait locus (QTL) with an effect on marbling to the centromeric region of bovine chromosome 14, with the gene encoding thyroglobulin (TG) being proposed as a positional and functional candidate gene for this QTL. Recently, the gene encoding diacylglycerol O-acyltransferase (DGAT1), which also has been mapped within the region of the marbling QTL, has been demonstrated to affect the fat content of milk. In the present study, the effects of a 5'-polymorphism of TG and of a lysine/alanine polymorphism of DGAT1 on the fat content of musculus (m.) semitendinosus and m. longissimus dorsi in 55 bovine animals (28 German Holstein and 27 Charolais) has been investigated. Significant effects were found for both candidate genes in both the breeds. These effects seem to be independent of one another because the alleles of the two polymorphisms showed no statistically significant disequilibrium. The DGAT1 effect is mainly on the m. semitendinosus. The TG polymorphism only affects m. longissimus dorsi. However, both intramuscular fat enhancing effects seem to be recessive. The possibility of two linked loci, acting recessively on intramuscular fat content, will require special strategies when selecting for higher marbling scores.

Acyltransferases↗

Search for pleiotropic QTL on chromosome BTA6 affecting yield traits of milk production.

The primary aim of this study was to investigate whether previous findings of similar quantitative trait loci (QTL) positions for correlated yield traits are due to a pleiotropic QTL. We applied a multitrait variance component based QTL mapping method to a dataset involving five granddaughter families from the German Holstein dairy cattle population. The marker map contained 16 microsatellite markers, distributed across chromosome BTA6. A chromosomewise significance threshold was used, because BTA6 is known to harbor QTL for several milk traits. To evaluate the results from the multivariate, across-family analysis, we also conducted single-family analyses using the least squares method of QTL estimation. The results provided two significant QTL findings at 49 and 64 cM for milk yield in different families and putative QTL at 68 cM for fat yield and at 71 cM for protein yield in another family. The results for fat and protein yield were confirmed by a univariate, across-family variance components analysis. The multivariate analysis of three bivariate trait combinations resulted in a significant pleiotropic QTL finding at 68 cM for fat yield and protein yield, bracketed by markers TGLA37 and FBN13. The estimates of variance contribution due to this QTL were 23% and 25%, respectively.

Analysis of Variance↗

Mapping of the bovine blood group systems J, N', R', and Z show evidence for oligo-genetic inheritance.

Genes determining the bovine erythrocyte antigens were mapped by linkage analysis. In total 9591 genotypes of 20 grandsire families with 1074 sires from a grand-daughter design were elucidated for the genes determining the erythrocyte antigens EAA, EAB, EAC, EAF, EAJ, EAL, EAM, EAN', EAR', EAS, EAT', and EAZ according to standard paternity testing procedures in the blood typing laboratories. Linkage analyses were performed with 248 microsatellite markers, eight SSCP markers and four polymorphic proteins and enzymes covering the 29 autosomes and the pseudoautosomal region of the sex chromosomes. The number of informative meioses for the blood group systems ranged from 76 to 947. Blood group systems EAM and EAT' were non-informative. Most of the erythrocyte antigen loci showed significant linkage to a single chromosome and were mapped unequivocally. The genes determining erythrocyte antigen EAA, EAB, EAC, EAL, and EAS were mapped to chromosomes 15, 12, 18, 3, and 21, respectively. Lod-score values ranged from 11.43 to 107.83. Moreover, the EAF system could be mapped to chromosome 17. However, the EAN' system previously known as part of the EAF system could be mapped to chromosome 5. In addition, the blood group systems EAJ, the new EAN', EAR', and EAZ, showed significant linkage to microsatellite markers on various chromosomes and also to other blood groups. The appearance of a single blood group system might be therefore either dependent on the existence of other blood group systems or because of an interaction between different loci on various chromosomes as is known in humans and in pigs.

Animals↗

Sex determination in cattle based on simultaneous amplification of a new male-specific DNA sequence and an autosomal locus using the same primers.

A PCR-based method for sex determination of bovine DNA samples and embryo biopsies is presented. Using only one primer pair both the male-specific sequence FBNY (127 bp) and a sex-independent control PCR-fragment, the microsatellite marker FBN17 (136-140 bp) are generated in the same PCR reaction. Synteny mapping assigned the male-specific sequence to bovine chromosome Y (BTA Y), whereas FBN17 was mapped to bovine chromosome 2. Localisation of FBNY on BTA Y was confirmed by fluorescence in hybridisation of two BAC clones containing the male-specific sequence. There was no amplification of the male-specific target sequence FBNY in sheep, pig, goat, mice, man, and several wild species of the tribe Bovini. The bovine male-specific fragment was detected in dilutions containing as little as 10 pg genomic DNA and in blastomeres from embryo biopsies. The PCR assay presented here does require neither restriction endonuclease digestion of the PCR product nor additional nested PCR steps. Owing to the advantage of parallel amplification of the autosomal locus FBN17 no additional control fragment is necessary to detect PCR failure. The results of sex determination in embryo biopsies using FBNY were in agreement with the outcome from a reference assay used in commercial breeding programs.

Animals↗

A whole genome scan for differences in recombination rates among three Bos taurus breeds.

Twenty paternal half-sib families of a granddaughter design were genotyped for 265 genetic markers, most of them microsatellites. These were 16 Holstein families, 3 Simmental families, and 1 Brown Swiss family. The number of sires per breed was 872, 170, and 32, respectively. Two-point recombination rates were estimated both jointly for all breeds and each single breed separately. Of 1168 marker intervals, 865 provided estimates for at least two breeds. Differences between breeds were tested by likelihood ratio tests. Four marker intervals, representing three genomic regions on BTA19, BTA24, and BTA27, show a significant impact of the breed at a false discovery rate of 0.23 and indicate a genetic component of observed heterogeneity of recombination. The variability of recombination rates between cattle breeds might not be a common feature of the whole genome, but rather might be restricted to certain chromosomal segments. Thus, attention should be paid to heterogeneities when pooling data of such regions from different breeds.

Animals↗

A mammary gland EST showing linkage disequilibrium to a milk production QTL on bovine Chromosome 14.

As part of a genome scan, ESTs derived from mammary gland tissue of a lactating cow were used as candidate genes for quantitative trait loci (QTL), affecting milk production traits. Resource families were genotyped with 247 microsatellite markers and 4 polymorphic ESTs. It was shown by linkage analysis that one of these ESTs, KIEL_E8, mapped to the centromeric region of bovine Chromosome (Chr) 14. Regression analysis revealed the presence of a QTL, with significant effect on milk production, in this chromosome region, and analysis of variance showed no significant interaction of marker genotype and family. The estimated significant differences between homozygous marker genotypes were 140 kg milk, -5.02 kg fat yield, and 2.58 kg protein yield for the first 100 days of lactation. Thus, there was strong evidence for a complete or nearly complete linkage disequilibrium between KIEL_E8 and the QTL. To identify the biological function of KIEL_E8, we extended the sequence for 869 bp by 5'-RACE. A 560-bp fragment of this shows a 90.9% similarity to a gene encoding a cysteine- and histidine-rich cytoplasmic protein in mouse. Although such a protein may have a regulatory function for lactation and a linkage disequilibrium between the EST marker and the QTL has been observed, it remains to be elucidated whether they are identical or not. Nevertheless, KIEL_E8 will be an efficient marker to perform marker-assisted selection in the Holstein-Friesian population.

Alleles↗

Isolation and characterization of hepatic and intestinal expressed sequence tags potentially involved in trait differentiation between cows of different metabolic type.

mRNA differential display was applied to identify hepatic and intestinal expressed sequence tags (ESTs) in lactating cows of different metabolic types (milk type, meat/milk type, meat type) that are potentially associated with energy turnover and involved in the regulation of these processes. Altogether, 277 ESTs (liver: 161, intestine: 116) were identified. For 150 transcripts (liver: 99, intestine: 51), the sequences showed similarity to previously described genes and ESTs. Many of these homologous sequences are reported to be involved in hepatic metabolism. Ninety-four ESTs (liver: 43, intestine: 51) did not match with any database entries. Semi-quantitative RT-PCR revealed quantitative differences in transcript represented by randomly chosen ESTs in liver samples of animals of the Holstein and Charolais breeds. One hundred twenty-two ESTs were mapped physically by using a bovine-hamster somatic cell hybrid panel (SCP) and a 5000-rad bovine whole genome radiation hybrid panel (WGRH). These ESTs were assigned to the bovine syntenic groups and positioned in the recently established RH-based ordered comparative map of the cattle and human genomes. The mapped, differentially expressed sequence tags are a useful prerequisite for cloning of genetic variation underlying economic traits.

Animals↗

[Pyoderma gangrenosum: and important differential diagnosis from wound infection. Case report of a life threatening course].

Pyoderma gangrenosum (PG) is a necrotizing and ulcerative skin disease of unknown cause. The pathogenesis is thought to be related to a defective immune response. The ulcerations appear spontaneously or after skin trauma. Development in a surgical wound can be misinterpreted as wound infection. However, in contrast to postoperative infections, treatment of PG requires immunosuppressive therapy. We report a case of PG following hip-joint surgery that was complicated by a severe life-threatening systemic inflammatory response syndrome (SIRS). Typically, wound and blood cultures were negative for pathogens. Prednisolone stopped the activity of the disease promptly.

Anti-Inflammatory Agents↗

A new family of high-affinity transporters for adenine, cytosine, and purine derivatives in Arabidopsis.

In many organisms, including plants, nucleic acid bases and derivatives such as caffeine are transported across the plasma membrane. Cytokinins, important hormones structurally related to adenine, are produced mainly in root apices, from where they are translocated to shoots to control a multitude of physiological processes. Complementation of a yeast mutant deficient in adenine uptake (fcy2) with an Arabidopsis cDNA expression library enabled the identification of a gene, AtPUP1 (for Arabidopsis thaliana purine permease1), belonging to a large gene family (AtPUP1 to AtPUP15) encoding a new class of small, integral membrane proteins. AtPUP1 transports adenine and cytosine with high affinity. Uptake is energy dependent, occurs against a concentration gradient, and is sensitive to protonophores, potentially indicating secondary active transport. Competition studies show that purine derivatives (e.g., hypoxanthine), phytohormones (e.g., zeatin and kinetin), and alkaloids (e.g., caffeine) are potent inhibitors of adenine and cytosine uptake. Inhibition by cytokinins is competitive (competitive inhibition constant K(i) = 20 to 35 microM), indicating that cytokinins are transported by this system. AtPUP1 is expressed in all organs except roots, indicating that the gene encodes an uptake system for root-derived nucleic acid base derivatives in shoots or that it exports nucleic acid base analogs from shoots by way of the phloem. The other family members may have different affinities for nucleic acid bases, perhaps functioning as transporters for nucleosides, nucleotides, and their derivatives.

Adenine↗