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Biomedical subjects

R Mendel

Publications and source records attributed to R Mendel.

12 recordsLinked to original sources
PubMed2001

Discordant prevalence of chlamydia trachomatis in asymptomatic couples screened using urine ligase chain reaction.

The following study was conducted to determine whether there would be an effect on the prevalence of Chlamydia trachomatis if both partners in a sexual relationship, rather than only one, underwent screening. First-void urine samples were collected from 1,690 asymptomatic women (mean age, 30 years; range, 15-70 years) and their male sex partners (mean age, 33 years; range, 16-71 years). The duration of sexual partnership for these subjects ranged from 2 months to more than 10 years.. At the time of testing, 687 of the women were pregnant. Ligase chain reaction testing revealed that 42 (2.5%) female and 63 (3.7%) male urine samples were positive. Detection rates for Chlamydia trachomatis differed for males and females, a difference that was found to be significant (P<0.0046, McNemar chi-square). Both partners tested positive in 27 (1.6%) couples, whereas at least one partner tested positive in 78 (4.6%) couples. Thus, screening males for Chlamydia trachomatis would have identified 63 (81%) of these 78 couples compared with only 42 (54%) couples had females been screened exclusively. In standard clinical practice, women most often undergo screening. The results of this study underscore the need to screen both males and females for Chlamydia trachomatis.

Adolescent↗
PubMed1998

The Chlamydomonas reinhardtii MoCo carrier protein is multimeric and stabilizes molybdopterin cofactor in a molybdate charged form.

In Chlamydomonas reinhardtii, molybdopterin cofactor (MoCo) able to reconstitute active nitrate reductase (NR) with apoenzyme from the Neurospora crassa mutant nit-1 was found mostly bound to a carrier protein (CP). This protein is scarce in the algal free extracts and has been purified 520-fold. MoCoCP is a protein of 64 kDa with subunits of 16.5 kDa and an isoelectric point of 4.5. In contrast to free MoCo, MoCo bound to CP was remarkably protected against inactivation under both aerobic conditions and basic pH. MocoCP transferred active MoCo to apoNR in vitro without addition of molybdate, though reconstituted activity was 20% higher in the presence of molybdate. Incubation with tungstate specifically inhibited MoCoCP activity but had no effect on the activity of free MoCo released from milk xanthine oxidase. MoCoCP did not charge molybdate unless in the presence of N. crassa extracts. Our data support that MoCoCP stabilizes MoCo in an active form charged with molybdate to provide MoCo to apomolybdoenzymes.

Animals↗
PubMed1995

Intron-dependent transient expression of the maize GapA1 gene.

Transient expression experiments show that the maize GapA1 promoter exhibits a requirement for sequences contained within intron 1 and surrounding exon border regions for expression in maize Black Mexican Sweet cells. Maize GapA1-promoter constructs lacking intron 1 are inactive. Intron 1 and its exon border sequences, when reintroduced into constructs lacking introns, restore gene activity whereas intron 2 and its exon borders to not. The minimal promoter so defined encompasses roughly 250 bp upstream of the in vivo transcription start and appears also to include intron 1. An octameric sequence was identified in intron 1 of maize GapA1 which is similar to sequence motifs found in other maize introns known to increase transient expression. Partial restoration of gene expression in GapA1 constructs lacking intron 1 was achieved through insertion of the identified octameric sequence.

Base Sequence↗
PubMed1987

[Highly differentiated adenocarcinoma in a villous adenoma of the common bile duct near the papilla].

A 65-year-old man, in hospital for treatment for bladder carcinoma, was by chance found also to have a so far asymptomatic obstructive jaundice with hydrops of the gallbladder. Endoscopic retrograde cholangiography revealed, in addition to a papilla distorted by tumour, a clearly obstructed choledochal duct with dilated intrahepatic bile ducts, caused by a 2-3 cm prepapillary intraductal choledochus tumour, which in the biopsy specimen corresponded to papillomatous structures with occasional medium-grade epithelial dysplasias. The patients, who initially declined operation, was five weeks later re-admitted with the clinical picture of an acute abdomen. In view of the history the surgeon performed a partial duodenopancreatectomy despite the acute emergency. Histology revealed a highly differentiated adenocarcinoma within a villous adenoma of the choledochal duct near the papilla.

Adenocarcinoma↗
PubMed1986

A binary vector for transferring genomic libraries to plants.

The transformation of mutant plants with a complete recombinant library derived from wild-type DNA followed by assay of transformed plants for complementation of the mutant phenotype is a promising method for the isolation of plant genes. The small genome of Arabidopsis thaliana is a good candidate for attempting this so-called shotgun transformation. We present the properties of an A. thaliana genomic library cloned in a binary vector, pC22. This vector, designed to introduce genomic libraries into plants, contains the oriV of the Ri plasmid pRiHR1 by which it replicates perfectly stably in Agrobacterium. Upon transfer of the library from E. coli to A. tumefaciens large differences in transfer efficiencies of individual recombinant clones were observed. There is a direct relation between transfer efficiency and stability of the recombinant clones both in E. coli and A. tumefaciens. The stability is independent of the insert size, but seems to be related to the nature of the insert DNA. The feasibility of shotgun transformation and problems of statistical sampling are discussed.

Cloning, Molecular↗