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Biomedical subjects

J Mohr

Publications and source records attributed to J Mohr.

At least 19 recordsLinked to original sources
PubMed1992

[Preclinical and prenatal diagnosis of familial adenomatous polyposis].

In order to investigate the possibility of preclinical and prenatal genetic diagnosis of familial adenomatous polyposis (FAP) by means of DNA-systems and other markers, blood samples were collected from 246 persons in 29 families, including 90 with the clinical diagnosis FAP and 73 clinically unaffected first degree relatives (persons at risk). The material was studied with up to 4 DNA-marker systems located in the region around the disease gene. Among the first degree relatives eight (11%) had probably inherited the disease gene, while 31 persons (42%) in this risk group had probably not inherited the gene. It was not possible to evaluate the risk in the remaining 34 persons (47%). In 45 (85%) out of 53 persons under 40 years the DNA-systems were informative, so that it would be possible to offer the option of prenatal diagnosis. It is concluded that preclinical and possibly prenatal genetic diagnosis may be offered; but the current practice of prophylactic proctosigmoidoscopic surveillance should be maintained.

Adenomatous Polyposis Coli↗
PubMed1992

Mesna side effects which imitate vasculitis.

Mesna (sodium-2-mercaptoethansulfonate) is used in the prophylaxis of cyclophosphamide (CYC)-induced hemorrhagic cystitis. Four patients being treated with "low dose" CYC and prednisone for vasculitis developed severe side effects to Mesna. Fever, arthralgia, myalgia, tachycardia, electrocardiogram changes consistent with perimyocarditis, erythroderma, bullous skin and mucous membrane lesions, and abdominal complaints with profuse diarrhea were noted approximately 3 weeks after the initiation of therapy for CYC-induced leukopenia and a conservatively reduced prednisone dosage. Positive reexposure tests confirmed the association to Mesna use, and hypersensitivity skin tests demonstrated a delayed hypersensitivity reaction.

Adult↗
PubMed1991

Inhibition of prolyl hydroxylation and procollagen processing in chick-embryo calvaria by a derivative of pyridine-2,4-dicarboxylate. Characterization of the diethyl ester as a proinhibitor.

The biochemical and morphological consequences of procollagen prolyl 4-hydroxylase inhibition by pyridine-2,4-dicarboxylic acid (2,4-PDCA) and its diethyl ester (diethyl-2,4-PDC) were studied in chick-embryo calvaria, which predominantly synthesize type I collagen. Half-maximal inhibition of tissue hydroxyproline formation required 650 microM-2,4-PDCA, whereas the Ki with respect to chicken prolyl 4-hydroxylase in vitro was 2 microM. In contrast, half-maximal inhibition was caused by 10 microM-diethyl-2,4-PDC in the intact calvaria, although chicken prolyl 4-hydroxylase in vitro was not inhibited even at 1 mM. The collagenous material produced in the presence of diethyl-2,4-PDC showed an altered 'melting' profile and a lowering of the transition temperature by 10 degrees C, indicating misalignment and thermal instability of its triple-helical structure. Amount and electrophoretic mobility of procollagen type I chains were increased in a dose-dependent manner. The amounts of partially processed species and alpha-chains were decreased, without change in mobility. This marked effect on procollagen-collagen conversion in the intact calvaria suggests that the underhydroxylated collagenous material generated in the presence of diethyl-2,4-PDC is resistant to or acts as endogenous secondary inhibitor of type I procollagen N-proteinase. Electron microscopy of treated calvaria cells showed dilated rough endoplasmic reticulum and numerous phagolysosomes, indicating intracellular retention and lysosomal degradation of the newly synthesized underhydroxylated collagenous material. In summary, these results identify 2,4-PDCA and diethyl-2,4-PDC as the first prolyl 4-hydroxylase-directed inhibitor/proinhibitor pair that affects intra- and extra-cellular events during collagen formation.

Animals↗
PubMed1991

Teaching mechanical ventilation.

Participants have stated that having actually experienced the modes of the ventilator and the components of weaning parameters, they are better able to understand and manage ventilated patients, as opposed to trying to memorize them as in the past. They also have a much greater appreciation for the discomfort experienced by the ventilated patient. (Most students cannot tolerate a PEEP of 10 centimeters of H2O for more than a few minutes). Many remarked that they are much more tolerant with their agitated, intubated patients because they can now understand their agitation. The session has proved to be an effective teaching tool. It is cost effective, does not take long and is enthusiastically received by the participants who believe they have gained a better understanding of how to properly care for their anxious, intubated patients.

Education, Medical↗
PubMed1990

An MHC (HLA-A, -B, C2, BF, HLA-DR, GLO1) haplotype study of 497 Danish normal families with 1970 children including 97 twin pairs.

Extended MHC haplotypes comprising HLA-A, -B, -DR, C2, BF and GLO1 loci observed in the parents of 497 Danish normal families are presented, with particular regard to the haplotypes that include BF variants or the C2*2 allele. The known association of HLA-B35, -DR1 with both -A3 and -A11 appeared to depend upon the BF type: HLA-B35, BF*S, -DR1 is strongly associated with -A11, whereas -B35,BF*F,-DR1 is strongly associated with -A3. Further, in the present material DZ twins of the same sex shared HLA-haplotypes more often than did twin pairs of different sex.

Denmark↗
PubMed1990

[Detection of IgG antibodies against rubella virus using the "Rubella-IgG-EIA SSW" test kit].

A new commercial ELISA test kit "Rubella-IgG-EIA SSW" is described for the determination of IgG antibodies to rubella virus. A panel of 99 sera was tested by "Rubella-IgG-EIA SSW" and by hemagglutination-inhibition (HI test). The results of enzyme-immunoassay (EIA) and of HI test correlate well; the coefficient of correlation is 0.95, the specificity is 90.9% and the sensitivity is 100%. A coefficient of correlation was found out of 0.92 between EIA and HI test in the evaluation of the quantitative procedure. The test kit can be used for determination of immune status to rubella virus and for quantitative detection of rubella-IgG antibodies.

Enzyme-Linked Immunosorbent Assay↗
PubMed1989

Linkage between serum cholinesterase 2 (CHE2) and gamma-crystallin gene cluster (CRYG): assignment to chromosome 2.

Serum cholinesterase 2 (CHE2) was examined in a Danish material of normal families that has been tested earlier for 70-78 classical marker systems and 25 RFLP systems. DNA for RFLP typing was provided by transforming 16-year-old frozen lymphocytes. The frequency of allele CHE2*C5+ in the Danish population was found to be 0.0430. The highest lod score was between CHE2 and the gamma-crystallin gene cluster (CRYG) (zeta = 4.21 at theta = 0.00 in females). The scores were from a single family with 15 children. CHE2 may, accordingly, be assigned to the location of CRYG: chromosome 2, bands q33-q35.

Blood Grouping and Crossmatching↗
PubMed1989

Linkage between alpha 1B-glycoprotein (A1BG) and Lutheran (LU) red blood group system: assignment to chromosome 19: new genetic variants of A1BG.

alpha 1B-glycoprotein (A1BG) polymorphism was examined in a Danish family material (no. 604-1505) with particular regard to markers on chromosome 19. For A1BG-LU we found a lod score z = 3.06 at theta = 0.05 in males, and z = 1.42 at theta = 0.10 in females, which assigns A1BG to chromosome 19. Close linkage to C3, SE, PEPD, APOC2, D19S7, D19S8 and D19S9 was excluded. The most likely order would appear to be C3-SE-LU-A1BG.

Alleles↗
PubMed1987

Time-dependent inactivation of chick-embryo prolyl 4-hydroxylase by coumalic acid. Evidence for a syncatalytic mechanism.

From the structure-activity relationships of known competitive inhibitors, coumalic acid (2-oxo-1,2H-pyran-5-carboxylic acid) was deduced to be a potential syncatalytic inhibitor for chick-embryo prolyl 4-hydroxylase. The compound caused time-dependent inactivation, the reaction rate being first-order. The inactivation constant was 0.094 min-1, the Ki 17 mM and the bimolecular rate constant 0.09 M-1 X S-1. Human prolyl 4-hydroxylase and chick embryo lysyl hydroxylase were also inactivated, though to a lesser extent. Inactivation could be prevented by adding high concentrations of 2-oxoglutarate or its competitive analogues to the reaction mixture. In Lineweaver-Burk kinetics, coumalic acid displayed S-parabolic competitive inhibition with respect to 2-oxoglutarate. The inactivation reaction had cofactor requirements similar to those for the decarboxylation of 2-oxoglutarate. Enzymic activity was partially preserved in the absence of iron, but the rescue was incomplete, owing to decreased stability of the enzyme under this condition. Coumalic acid also decreased the electrophoretic mobility of the alpha-subunit, but the beta-subunit was not affected. Prolonged incubation of coumalic acid above pH 6.8 led to loss of its inactivating potency, owing to hydrolysis. It is concluded that the inactivation of prolyl 4-hydroxylase by coumalic acid is due to a syncatalytic mechanism. The data also suggest that the 2-oxoglutarate-binding site of the enzyme is located within the alpha-subunit.

Animals↗
PubMed1987

Major genes of eye color and hair color linked to LU and SE.

Eye color and hair color were studied in a large Danish family material, tested earlier for a comprehensive set of genetic marker systems. We found strong evidence for linkage of "green eye color" or GEY to the Lutheran-Secretor systems (combined lod score 9.19). This would appear to identify a major gene with influence towards "green eye color". We also found evidence for linkage of GEY to "brown hair color" or BRHC (lod score 5.06), which would appear to identify a second major gene influence in the same region of chromosome 19. Concerning the obvious association in the general population between eye color and hair color which could imitate linkage if it were reflected within sibships, we did not recognize any such intrafamilial association; in the pooled informative sibships GEY and BRHC were independently distributed (as were LU-SE and GEY).

ABO Blood-Group System↗
PubMed1987

Dyslexia and chromosome 15 heteromorphism: negative lod score in a Danish material.

From a large Danish material of random families we selected families with dyslexia as reported by the families themselves and as recorded by a dyslexia institute. Among five "backcross families" studied for chromosome 15 polymorphisms we found only negative lod scores, and at theta = 0.10 a negative score of -3.42; i.e., in our material we did not find any confirmation of the indication of linkage between dyslexia and a chromosome 15 polymorphism found in part of their material by Smith et al. (1983, 1986).

Chromosomes, Human, Pair 15↗
PubMed1987

Major locus for red hair color linked to MNS blood groups on chromosome 4.

Red hair color (RHC) was studied in a Danish material of normal families that was tested earlier for 65 marker systems. We found 4.85% of the parents to be red-haired or to have been so early in life. Scoring RHC for linkage as an autosomal dominant against blond and as hypostatic to dark hair gave a lod score of z = 5.50 at theta = 0.05 in males and theta = 0.24 in females for the MNS blood group system; this assigns a major locus for red hair to chromosome 4.

Chromosome Mapping↗
PubMed1987

Suggestion of linkage of a major locus for nonsyndromic orofacial cleft with F13A and tentative assignment to chromosome 6.

A Danish material of 58 pedigrees with nonsyndromic orofacial cleft, selected out of a comprehensive Danish material for suggestiveness of autosomal dominant inheritance, was studied for linkage with 42 non-DNA polymorphic marker systems. Both cleft lip with or without cleft palate (CL(P)) and cleft lip alone (CP) were, for the purpose of linkage analysis, scored as if they were due to an autosomal dominant gene with complete penetrance. The highest lod score was with the blood clotting factor XIIIA (F13A): for males alone z = 3.40 at theta = 0.00, for females alone z = 0.30 at theta = 0.21, and for these together z = 3.66 at at theta = 0.00 for males and 0.26 for females. Since F13A is known to be located distally on chromosome 6, we tentatively assign a major locus for orofacial cleft to this region. Since both CL(P) and CP pedigrees contribute to the positive score, the question arises whether this locus carries two cleft alleles.

Chromosome Mapping↗
PubMed1987

A comparison of the teaching effectiveness of the didactic lecture and the problem-oriented small group session: a prospective study.

A prospective study was designed to assess the teaching effectiveness of active learning in problem-oriented small group sessions (POSGS) compared with passive learning in didactic lectures (DL). Third-year medical students participated in a POSGS on breast disease and a standardized DL on thyroid disease (N = 23) or participated in a POSGS on thyroid disease and a DL on breast disease (N = 19). Students were tested with a multiple-choice examination (MCQ) and a highly structured oral examination (OE) administered by faculty members blinded about student group. Results of a between-within analysis of variance performed separately for breast and thyroid disease yielded significant group differences because of instructional method for thyroid disease (p = 0.003) and approached significance for breast disease (p = 0.095). Although no significant interactions were detected with percentage scores, a significant interaction between group membership and test type was noted for thyroid disease when the percentage scores were transformed to Z scores. We conclude that regardless of topic or testing method, students in POSGS tended to perform better than students in a DL and that the POSGS offers significant advantages over the DL in teaching surgery to third-year medical students.

Breast Diseases↗
PubMed1986

Identity of the polymorphisms for esterase D and S-formylglutathione hydrolase in red blood cells.

The S-formylglutathione hydrolase (FGH) polymorphism of human red blood cells was studied in unrelated individuals, both by isoelectric focusing and starch gel electrophoresis, and with the substrates S-acetylglutathione and 4-methylumbelliferyl-acetate (the standard substrate for esterase D (ESD]. With both separation techniques the two substrates consistently gave similar and identically located zymograms. Thus, FGH (E.C.3.1.2.12) appears to be identical to ESD (E.C.3.1.1.1).

Carboxylesterase↗