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Biomedical subjects

M Johansson

Publications and source records attributed to M Johansson.

At least 199 records · Page 11Linked to original sources
PubMed1995

The lactase phlorizin hydrolase (LCT) gene maps to pig chromosome 15q13.

A porcine 17kb genomic fragment was used as probe to map the lactase phlorizin hydrolase (LCT) gene to pig chromosome 15q13 by fluorescence in situ hybridization. Further, a three-allele TaqI RFLP was used to add the LCT gene to the proximal end of the chromosome 15 linkage map. Comparison of the human chromosome 2 gene map and the gene map of pig chromosome 15 indicates that the part of human chromosome 2 distal to the q13 band is homologous to pig chromosome 15.

Animals↗
PubMed1995

The porcine intestinal receptor for Escherichia coli K88ab, K88ac: regional localization on chromosome 13 and influence of IgG response to the K88 antigen.

The loci encoding the porcine intestinal receptors for Escherichia coli K88ab and K88ac (K88abR and K88acR) were firmly assigned to chromosome 13 by linkage analysis using a three-generation pedigree. The linear order of these loci and seven other markers on chromosome 13 was determined by multipoint analyses. The K88abR and K88acR loci were tightly linked (theta = 0.01, zeta = 41.06) with the K88abR locus localized 7.4 cM (sex average) proximal to the transferrin locus. The results, together with previous reports from two other groups, provide an unequivocal assignment of the K88 receptor loci to chromosome 13, and reject a previous assignment to chromosome 4. Pigs possessing the receptor had a slightly higher specific IgG response to the K88 antigen after an intramuscular immunization with an E. coli vaccine.

Animals↗
PubMed1995

In situ hybridization mapping of a 500-kDa calcium-sensing protein gene (LRP2) to human chromosome region 2q31-->q32.1 and porcine chromosome region 15q22-->q24.

Recently, a 500-kDa protein, with homology to the rat Gp330 glycoprotein, was found to be expressed on the surface of human parathyroid, placental cytotrophoblast, and renal proximal tubule cells. The protein has been implicated to function as a sensor of extracellular calcium on parathyroid and placental cytotrophoblast cells. We report here in situ hybridization mapping of the corresponding gene, designed as low-density lipoprotein receptor related protein-2 and symbolized as LRP2, to human chromosome region 2q31-->q32.1 and porcine chromosome region 15q22-->q24. The results are discussed in a comparative mapping context.

Animals↗
PubMed1995

Factors affecting the formation and yield of heterocyclic amines.

The main food mutagens found in cooked meat products are heterocyclic amines. The formation of these heterocyclic amines has been shown to require three classes of precursors: (i) creatine/creatinine, (ii) free amino acids or dipeptides, and (iii) sugar. The mutagen forming reactions were investigated in model systems and several heterocyclic amines (IQx, MeIQx, DiMeIQx, TriMeIQx and PhIP) were identified and quantified. A number of mutagenic fractions produced in the model system are not yet identified, among them one having a mass number of 217. A participation of the Maillard reaction in the formation of the heterocyclic amines was proposed ten years ago. Since then, the support for this route has increased, especially in a recent study in which carbon atoms from 14C-labelled glucose were shown to be incorporated into MeIQx and DiMeIQx. Other studies have shown sugar to either enhance or inhibit the yield of mutagenic activity depending on its molar ratio relative to the other reactants. Thus, the Maillard reaction can be utilized both to enhance and inhibit the formation of the heterocyclic amines. Olive oil and corn oil were found to almost double the yield of MeIQx in the model system after heating for 30 minutes at 180 degrees C. When adding deep-fat frying oil of different oxidation status in the model system, the yield of MeIQx was not affected by oxidation status or presence of vitamin E, but the lipids enhanced the formation of MeIQx by 30% after heating at 180 degrees C for 30 minutes. Artificial production of free radical reactions by adding FeSO4, hydrogen peroxide and oxygen to the model system doubled the yield of MeIQx.

Carcinogens↗
PubMed1994

A physically anchored linkage map of pig chromosome 1 uncovers sex- and position-specific recombination rates.

A linkage map of pig chromosome 1 (SSC1) has been constructed using 15 polymorphic markers. Eleven markers constitute PCR-based microsatellites (three associated with coding sequences), six markers have also been mapped by in situ hybridization, and homologues to four of the markers have been mapped in human. The physical assignments show that almost the entire SSC1 is covered by the linkage map, which measures 164 cM (sex-averaged). In a large region on the q arm, representing about 40% of the chromosome, there is a significant excess of male recombination. In contrast, there is a significantly higher recombination rate in females in both terminal regions. In the penultimate marker intervals on the q arm as well as the p arm, females show a fivefold excess of recombination compared to males. The rate of genetic recombination in relation to the physical DNA content is 1 cM per 2-4 Mb over at least 80% of the chromosome. In the terminal part of the q arm, however, there is a tremendous increase in the recombination rate, with 1 cM equaling about 0.4 Mb. Two homologous chromosome segments in human could be detected, ESR-CGA on human chromosome 6 (HSA6) and IFNA-RLN-GRP78 on human chromosome 9 (HSA9). Since the porcine blood group locus EAA is located close to (or possibly within) the latter conserved segment and the suggested human counterpart, the ABO system, is similarly close to the segment on HSA9, our data provide indirect evidence that these blood group systems are homologous.

Animals↗
PubMed1994

Determination of 4-hydroxycyclophosphamide in plasma, as 2,4-dinitrophenylhydrazone derivative of aldophosphamide, by liquid chromatography.

A reversed-phase liquid chromatographic method to determine the concentration of 4-hydroxycyclophosphamide, a labile cytotoxic metabolite of cyclophosphamide, in plasma is described. In order to stabilize 4-hydroxycyclophosphamide, as well as to increase the selectivity and the sensitivity, a 2,4-dinitrophenylhydrazone derivative was formed. Plasma proteins were precipitated with acetonitrile prior to the derivatization with 2,4-dinitrophenylhydrazine at pH 2. The derivatization was performed at 50 degrees C for 5 min. The chromatographic system consisted of an octadecyl silica column and a mobile phase containing phosphate buffer and acetonitrile. Quantitation was performed using an UV detector operating at 357 nm. Optimal derivatization was obtained by adding 0.2 ml 2,4-dinitrophenylhydrazine (3.8 mg/ml) to 0.5 ml of the deproteinized plasma supernatant. The relative recovery of 4-hydroxycyclophosphamide from plasma is > or = 97%. Concentration levels down to 22 mg/ml of 4-hydroxycyclophosphamide in plasma could be determined with a R.S.D. of about 13%. No degradation of the derivative was observed after 24 h at room temperature. The t1/2 for 4-hydroxycyclophosphamide in blood is ca. 4 min at 37 degrees C, whereas 4-hydroxycyclophosphamide is stable for at least 1 h at 4 degrees C. Application of the method for the pharmacokinetic monitoring of 4-hydroxycyclophosphamide is described.

Breast Neoplasms↗
PubMed1994

2 cloning and expression of mouse deoxycytidine kinase. Pure recombinant mouse and human enzymes show differences in substrate specificity.

A cDNA encoding mouse deoxycytidine kinase (dCK) (EC 2.7.1.74) was cloned from a mouse T-cell lambda ZAP cDNA library. An insert of 2.8 kilobases (kb) contained the entire coding sequence of 780 base pairs. The protein coding sequence was 88% homologous at the nucleotide level with human dCK cDNA (Chottiner, E. G., Shewach, D. S., Datta, N. S., Ashcraft, E., Gribbin, D., Ginsburg, D., Fox, I. H., and Mitchell, B. S. (1991) Proc. Natl. Acad. Sci. U. S. A. 88, 1531-1535). At the amino acid level the homology was greater with only 16 of the 260 amino acids being different. Northern blot analyses revealed a size of 3.4 kb for mouse dCK mRNA as compared with 2.8 kb for human dCK. Part of the 3'-untranslated region was conserved between human and mouse dCK cDNA in contrast to the remainder of the 3'-sequence which was unrelated and about 500 nucleotides longer in mouse dCK cDNA. Mouse dCK cDNA showed cross-hybridization with several bands in EcoRI-digested genomic DNA from seven different mammalian species and chicken but not with yeast DNA. Both mouse and human dCK were cloned into the T5 promotor pQE30 vector system, expressed in Escherichia coli and purified to homogeneity. The kinetic constants for dCyd phosphorylation were similar for the human and mouse enzymes and also similar to what previously has been observed for dCK purified from human tissues. Mouse dCK was less efficient with regard to dAdo, dGuo, and ddCyd phosphorylation as compared with human dCK when using ATP as phosphate donor in a phosphoryl transfer assay.

Amino Acid Sequence↗
PubMed1994

Karyotypic characterization of bronchial large cell carcinomas.

Cytogenetic analysis of short-term cultures from 26 primary bronchial large cell carcinomas and 1 metastasis from a primary large cell carcinoma revealed clonal chromosome abnormalities in 20 tumors and a normal karyotype in 6. No outgrowth was obtained in 1 case. Simple aberrations were present in 3 tumors; in 1, the only change was a reciprocal translocation between chromosomes 1 and 6, in another the sole anomaly was a supernumerary marker ring chromosome and in a third loss of the Y chromosome was the only clonal change. The remaining 17 tumors had complex karyotypes. The chromosomes most frequently involved in structural rearrangements were chromosomes 1, 2, 3, 5, 6, 7, 8, 10, 11, 13, 14 and 17. The bands most frequently affected were 1q11-12, 1p13, 7q11, and 17p11-13. The rearrangements led to repeated losses of 1p, 1q, 3p, 6q, 7q and 17p and gains of 5q and 7p. The emerging karyotypic picture of large cell lung carcinomas indicates more similarities with adenocarcinomas than with other pathologic subgroups of lung cancer.

Aged↗
PubMed1994

Genetic mapping of quantitative trait loci for growth and fatness in pigs.

The European wild boar was crossed with the domesticated Large White pig to genetically dissect phenotypic differences between these populations for growth and fat deposition. The most important effects were clustered on chromosome 4, with a single region accounting for a large part of the breed difference in growth rate, fatness, and length of the small intestine. The study is an advance in genome analyses and documents the usefulness of crosses between divergent outbred populations for the detection and characterization of quantitative trait loci. The genetic mapping of a major locus for fat deposition in the pig could have implications for understanding human obesity.

Adipose Tissue↗
PubMed1994

Re-initiated growth from mature ventral mesencephalon: an in oculo transplant study of nigrostriatal co-grafts.

The ability of mature dopaminergic neurons derived from ventral mesencephalon to re-initiate growth after making contact with a non-innervated target was studied using the intra-ocular grafting model. Foetal ventral mesencephalic tissue or brain stem including the locus coeruleus area was grafted to the anterior chamber of the eye. Two weeks, 6 weeks or 1 year after the first implantation, foetal striatal tissue was placed in contact with the nigral graft or grafted alone. The size of the transplants was measured through the cornea. The final size of the striatal grafts was significantly larger when placed alone than when co-grafted with 1-year-old or 6-week-old dopaminergic grafts. Striatum grafted together with 2-week-old nigra was larger than when grafted adjacent to mature substantia nigra, but not significantly so. Nerve fibre outgrowth into the iris from the nigral transplants did not increase after maturation, but the re-innervated area of the host iris progressively increased around the locus coeruleus grafts. Ingrowth of tyrosine hydroxylase (TH) immunoreactive nerve fibres into the striatal grafts was studied 6 weeks after the second implantation. TH immunohistochemistry revealed innervation of the striatal piece in all cases, except for the group where striatum alone was grafted. With the short survival time for co-grafts of 6 weeks, TH-positive nerve fibres innervated a larger volume, had a patchy appearance and the density was higher in striatum grafted to 2 week-old nigral transplants than that seen in striatal transplants grafted to mature nigral grafts. The patchy pattern of TH-immunoreactive nerve terminals was also seen in striatum co-grafted with 6-week-old or 1-year-old nigral transplants. No difference in striatal innervation volume was detected between those latter two groups. When striatum was implanted adjacent to mature ventral mesencephalon and grown together for 6 months--the longer survival time--the same dense TH-positive innervation as seen in striatum co-grafted with immature nigral tissue at the shorter survival time was found. Additionally, the nigral part of the co-grafts showed increased TH-immunoreactive nerve fibre density. In conclusion, dopaminergic neurites from mature ventral mesencephalic transplants can re-initiate growth if placed in contact with non-innervated striatal tissue. The nigral grafts do not progressively re-innervate the host iris, while locus coeruleus grafts do. The intra-ocular grafting model can be used to study the in vivo effects of trophic factors on mature dopaminergic neurons.

Aging↗
PubMed1994

Linkage maps of porcine chromosomes 3, 6, and 9 based on 31 polymorphic markers.

Linkage maps of porcine Chromosomes (Chrs) 3, 6, and 9, based on 31 polymorphic markers, are reported. The markers include 14 microsatellites, 12 RFLPs, three protein polymorphisms, and two blood group loci. The genetic interpretations of 11 RFLPs are documented. The markers were scored in a three-generation Wild Boar/Large White pedigree, and genetic maps were constructed on the basis of two-point and multi-point linkage analysis. Altogether the maps span a genetic distance of 216 cM, and previous physical assignments indicate that the linkage groups cover major parts of the three chromosomes. Significant differences in recombination rates between the sexes were observed for all three chromosomes. The recombination rate on the q arm of Chr 6 was markedly low. Sixteen loci are informative with regard to comparative mapping, that is, they have previously been mapped in the human and/or mouse genomes.

Animals↗