Experimental and clinical studies on AMCA, the antifibrinolytically active isomer of p-aminomethyl cyclohexane carboxylic acid.
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Biomedical subjects
Publications and source records attributed to L Andersson.
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Two enzymes, phosphoglycerate mutase and peroxidase, were purified by using an immobilized metal ion adsorbent for the removal of unwanted proteins. The mutase was obtained pure from a single column, whereas the purification of peroxidase required the use of a thiophilic adsorbent in a tandem. The capacity was 2.5 mg pure peroxidase per mL gel.
A representative sample of non-institutionalized elderly persons between 65 and 74 years living in Stockholm county, Sweden responded to a self-report health questionnaire. Special life events and their subsequent effects were examined in the context of health attitudes and health behavior. Of the 370 respondents, 128 reported experiencing a special life event. The resulting effects of life events were categorized into one of six groups: smoking, alcohol, diet, restricted mobility, existential circumstances and a miscellaneous group. Positive associations between life events and health attitudes and health behavior were discovered. This was particularly evident in the diet and the restricted mobility group. The findings suggest that the occurrence of life events and subsequent effects can contribute to health promotive behavior despite the potential worries, poor health and diseases which may also be associated with them.
Cell segregation into nondividing states and lysis was found to dominate the growth behavior of high cell density fed batch cultures of Escherichia coli. When the specific growth rate declined below a critical value, the biomass production, oxygen consumption, and carbon dioxide formation rates declined sharply. Concomitantly, an extensive loss of colony-forming ability (cfu) and accumulation of extracellular proteins was observed. A segregated model that considered different physiological states, including dividing, nondividing, and lysed cells, was developed and applied to experimental data from high cell density cultures of E. coli.
The entry of Escherichia coli into glucose starvation is connected to the induction of both the stringent response and the general stress response. The concentration of the corresponding response regulators ppGpp and sigmaS (RpoS, KatF) was investigated during glucose-limited growth at different growth rates and with different cultivation strategies, including fed-batch fermentation, chemostat, and a continuous-cultivation technique with computer-controlled decrease of the feeding rate (A-stat). This study confirms the model of the in vivo effect of ppGpp on sigmaS by the direct measurement of ppGpp and sigmaS levels. The response of both regulators was clearly shown in situations where a nutrient shift occurs. A correlation in the concentration of both regulators was also shown under steady-state conditions. However, during transients with slow continuous changes of the nutrient availability, this concerted reaction of ppGpp and sigmaS is less apparent, indicating the specific importance of these regulators for the adaptation of the cells to fast changes of environmental parameters.
Lack of bone in localized areas of the jaws frequently poses a problem when placing oral implants. In this clinical study, we have tested an osteopromotive membrane technique for its ability to create bone over buccal fenestrations after fixture installation in the maxilla. 7 patients were selected by the use of CT-scan. Criteria for patient selection were that the alveolar crest should have a vertical height >13 mm and a facial-palatal concavity, where exposure at the central portion of the fixture could be anticipated. One fenestration, randomly chosen, in each patient was covered with an e-PTFE (expanded polytetrafluoroethylene) (Gore-Tex GTAM) membrane. Contralateral fenestrations served as controls (without the placement of a membrane). The amount of newly formed bone was calculated by photometric assessments. The results showed that the fixture fenestrations, treated with the membrane technique, demonstrated a significantly (p<0.005) higher amount of new bone formation compared to the controls, where little or no improvement had taken place at the fenestrations. The study conclusively shows that the membrane technique is a reconstructive technique, able to create new bone at localized bone fenestrations at titanium fixtures. Additionally, the study also demonstrates that the periosteum alone, in adult humans, is not capable of generating new bone at exposed titanium implants.
Linear regression analysis is considered the least computationally demanding method for mapping quantitative trait loci (QTL). However, simultaneous search for multiple QTL, the use of permutations to obtain empirical significance thresholds, and larger experimental studies significantly increase the computational demand. This report describes an easily implemented parallel algorithm, which significantly reduces the computing time in both QTL mapping and permutation testing. In the example provided, the analysis time was decreased to less than 15% of a single processor system by the use of 18 processors. We indicate how the efficiency of the analysis could be improved by distributing the computations more evenly to the processors and how other ways of distributing the data facilitate the use of more processors. The use of parallel computing in QTL mapping makes it possible to routinely use permutations to obtain empirical significance thresholds for multiple traits and multiple QTL models. It could also be of use to improve the computational efficiency of the more computationally demanding QTL analysis methods.
A linkage map of pig chromosome 6 was constructed using a wild pig/Large White intercross pedigree. The map comprises 23 polymorphic loci, and the sex-average map length is approximately 170 cM. The study adds three new genes to the chromosome 6 map: the extension (E) coat color locus, and the blood group O (EAO) and tyrosine aminotransferase (TAT) loci. Segregation at the E locus determined two coat color phenotypes among the F2 animals: wild-type color (El-) and black-spotting (Ep/Ep). The E locus showed close genetic linkage to the most distal marker (S0035) on the short arm of chromosome 6. Comparative coat color genetics as well as comparative mapping strongly suggest that E in pigs encodes the melanocyte-stimulating hormone receptor, as previously shown for the corresponding coat color loci in mouse and cattle. TAT was also mapped to the distal part of 6p, whereas EAO was the most distal marker on 6q. A clear tendency for a higher recombination rate in both terminal regions was observed. A model for the evolution of pig chromosome 6, based on comparative mapping data, is presented.
Intercrosses between divergent lines of domestic animals adapted to different environmental conditions and/or production systems provide unique opportunities for mapping phenotypic trait loci. The strategy resembles the use of interspecific crosses developed for general linkage mapping. We have made an intercross between the wild pig and domestic pigs of the Large White breed. A comprehensive linkage map comprising more than 230 genetic markers has been established. The successful use of this intercross for mapping loci for some monogenic traits (coat color and an intestinal receptor for E. coli K88 pili) as well as quantitative trait loci (QTLs) with major effects of growth and fatness is reviewed.
The degree of genetic polymorphism at the DRB3 locus in the major histocompatibility complex (Mhc) of the North American bison was investigated by PCR and DNA sequence analysis. Nine different alleles were characterized in a selected sample of 20 animals. The genetic distances between alleles were as large as usually found at highly polymorphic Mhc loci in other species. A comparative analysis of the DRB3 polymorphism in bison and cattle revealed an extensive sharing of sequence motifs. The result clearly shows a transspecies persistence of DRB3 allelic lineages in the two species. Consequently a significant amount of Mhc polymorphism has been maintained through the population bottleneck that bison experienced in the late nineteenth century. An analysis of the pattern of sequence polymorphism among bison and cattle DRB3 alleles strongly suggested that interallelic recombination has contributed significantly to the generation of allelic diversity at this locus.
Three previously described electrophoretic phenotypes of mitochondrial glutamate oxaloacetate transaminase (GOTM) in horse leukocytes are shown to be controlled by two codominant alleles at a single autosomal locus. The GOTM locus is linked to the serum esterase locus (Es), as no recombination between these loci was observed among 16 informative offspring in one sire family. The results assign GOTM to equine linkage group (LG) II. The hypothesis that a part of LG II (e-Es) shares homologies with mouse chromosome 8 is thus confirmed, as the murine homologue of GOTM is located within the cluster of esterase loci on chromosome 8. The assumed homology also involves rabbit LG VI, rat LG V, and human chromosome 16. The observation is a striking example of the conservation of linkage relationships between mammalian species.
Genetic linkage between the albino (c) and hemoglobin beta-chain (Hb beta) genes in rabbits was demonstrated by means of segregation data from one full-sib family. The map distance was estimated at 9 +/- 6 cM, which is similar to the 8 cM previously estimated between the same pair of loci in both mice and rats. The interspecies conservation of the chromosome segment comprising c and Hb beta thus extends outside the rodent family. Indications that it also may be conserved in man are discussed.
Southern blot analysis of genomic cattle DNA was carried out using murine cDNA probes representing the Tcp-1 gene of the t complex. Excellent cross-hybridization was obtained, and the probes apparently hybridized to at least two bovine TCP1 genes. Two independent restriction fragment length polymorphisms, each composed of two allelic variants, were detected; the inheritance of the restriction fragment length polymorphisms was confirmed by family data. One of the restriction fragment length polymorphisms, designated TCP1B, was evidently due to a gene duplication and was revealed with any restriction enzyme used. The duplication was found in three different cattle breeds investigated. Family segregation data indicated that TCP1B is linked to major histocompatibility complex genes. The result was consistent with close linkage to the major histocompatibility complex class II DO beta gene, whereas a fairly high recombination frequency was indicated between TCP1B/DO beta and other major histocompatibility complex genes. The result assigns TCP1B to a bovine linkage group previously comprising major histocompatibility complex class I and class II genes and blood group locus M. The similarity between this linkage group and parts of mouse chromosome 17 (t-H-2) and human chromosome 6 (TCP1-HLA) is discussed.
A size-fractionated (200-400 bp) porcine genomic library was screened with the dinucleotide motifs (TG)n and (TC)n. The number of TG- and TC-positive clones was 83 and four, respectively, implying that the former motif is more frequent in the porcine genome, as previously reported in other species. Twenty-six TG-clones were sequenced, and the number of repeats varied between 16 and 42 with different compositions of the repetitive sequences; 17 clones had a perfect stretch of TG-repeats, four had imperfect stretches, and five had a compound structure with TG-repeats followed by TC-repeats. Primers for DNA amplification using the polymerase chain reaction (PCR) were synthesized for six loci. Ten unrelated individuals (two wild boars and eight domestic pigs of the Swedish Yorkshire breed) were screened for microsatellite polymorphism. All six microsatellite loci were polymorphic with two to seven alleles and observed heterozygosities in the range of 0.42-0.84; the inheritance of the observed polymorphism was confirmed by family studies. The characteristics of microsatellites make them highly suitable as genetic markers, and these microsatellites were isolated as a part of a pig gene mapping project.
Genetic variation at the porcine submaxillary gland mucin (MUC) locus was revealed by RFLP analysis. A three-allele system was defined, and codominant inheritance was confirmed using a three-generation pedigree comprising 10 founder individuals, 26 F1 animals, and 200 F2 offspring. Linkage analysis was performed against a set of 56 genetic markers. The mucin locus was assigned to a previously reported linkage group comprising the markers interferon gamma (IFNG), diacylglycerol kinase (DAGK), and an anonymous microsatellite (S0092). Furthermore, the genes for mucin and interferon gamma were physically localized to porcine chromosome 5q2.3 and 5p1.2-q1.1 by fluorescence and radioactive in situ hybridization, respectively, thereby assigning four new markers to chromosome 5. This chromosome shares homologies with chromosome 5 in cattle and chromosome 12 in humans.
PURPOSE: Relative regional cerebral blood flow (rCBF) at rest was measured in 44 volunteers using both dynamic susceptibility contrast (DSC) MRI and (99m)Tc-HMPAO SPECT on the same day. METHOD: In MRI, a Gd-DTPA-BMA contrast agent bolus (0.3 mmol/kg body wt) was monitored with a simultaneous dual FLASH pulse sequence (time resolution 1.5 s). MRI-based rCBF images were calculated by singular value decomposition-based deconvolution of the measured tissue concentration-time curve with an arterial input function from a small artery within the imaging slice. In the SPECT investigation, 900 MBq of (99m)Tc-HMPAO was injected intravenously. Relative rCBF in gray matter in the thalamus and in frontal white matter was determined. RESULTS: The ratio of relative rCBF in gray matter to relative rCBF in white matter was 2.21 +/- 0.57 using MRI and 2.24 +/- 0.54 using SPECT (mean +/- SD). CONCLUSION: Relative rCBF maps from DSC MRI and (99m)Tc-HMPAO SPECT showed good agreement, and the MRI-based rCBF ratio correlated with the corresponding SPECT-based ratio (r = 0.79, p < 0.0000006).
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