[Perianal precancerous conditions (Bowen disease, Paget disease, Carcinoma in situ, Buschke-Lowenstein tumor)]. / Perianale Präkanzerosen (M. Bowen, M. Paget, Carcinoma in situ, Buschke-Löwenstein-Tumor).

Perianal premalignant lesions are rare. Any suspicious perianal lesion or any perianal exanthema, that does not heal by non-surgical treatment has to be biopsied for histology. Many premalignant lesions are diagnosed as an incidental finding after anorectal surgery: any anorectal specimen must be examined by the pathologist. Leukoplakia is a facultative premalignant condition. High-grade anal intraepithelial neoplasia (AIN) is an in situ squamous cell carcinoma, associated with papillomavirus infection. Bowen's disease and Bowenoid papulosis are clinical variations of high-grade AIN. Buschke-Löwenstein tumour (giant condyloma) is a locally destructive tumour, that does not infiltrate or cause metastases. Paget's disease is a premalignant lesion like AIN, associated with other malignancies.

Location, catalytic activity, and subunit composition of NAD-reducing hydrogenases of some Alcaligenes strains and Rhodococcus opacus MR22.

Six new strains of Alcaligenes enriched for and isolated as nickel-resistant bacteria resemble Alcaligenes eutrophus H16 and contain both an NAD-reducing, tetrameric soluble hydrogenase and a membrane-bound hydrogenase. None of the soluble hydrogenases share with the Rhodococcus opacus MR11 enzyme tetramer the property of being cleaved easily into two dimeric moieties [a hydrogenase (betadelta) and an NADH:acceptor oxidoreductase (alphagamma)], in the absence of nickel or at low ionic strength. The soluble hydrogenase of the newly isolated strain MR22 of R. opacus equalled that of strain MR11. The absence of a membrane-bound hydrogenase in Alcaligenes denitrificans strain 4a-2 and in Alcaligenes ruhlandii was confirmed.

The giant linear plasmid pHG207 from Rhodococcus sp. encoding hydrogen autotrophy: characterization of the plasmid and its termini.

As described previously, in Rhodococcus sp. (formerly Nocardia opaca) strains MR11 and MR22, the ability to grow as an aerobic hydrogen bacterium (the Aut character) is located on giant conjugative linear plasmids--on pHG201 (270 kb) in strain MR11 and on pHG205 (280 kb) in strain MR22. In an autotrophic transconjugant originating from MR22 a smaller plasmid, pHG207 (225 kb), was detected and shown to be a recombination product of the wild-type plasmids pHG204 and pHG205. A donor carrying pHG207 as the sole plasmid transferred the Aut marker at a 1000-fold frequency compared to the wild-type plasmid pHG205. Analysis of the plasmid ends revealed that plasmid pHG207 carries proteins at both ends; the proteins are linked to the 5' ends of the strands. The cloned end fragments of about 2 kb were sequenced and found to contain highly homologous sequences within the terminal 583 bp (left end part) and 560 bp (right end part). Several potential reading frames were detected, but database searching gave no indication about possible functions.

Hydrogen autotrophy of Nocardia opaca strains is encoded by linear megaplasmids.

Several linear megaplasmids were detected in the facultatively lithoautotrophic Gram-positive bacterium Nocardia opaca. The wild-type strain MR11 contains, in addition to the cccDNA plasmids pHG31-a and pHG31-b, the linear plasmids pHG201 (270 kb), pHG202 (400 kb) and pHG203 (420 kb). The wild-type strain MR22 contains, in addition to the cccDNA plasmid pHG33, the linear plasmids pHG204 (180 kb), pHG205 (280 kb) and pHG206 (510 kb). After preparation of DNA from cells embedded in agarose, the linear plasmids were demonstrated by pulsed-field electrophoresis. By means of DNA probes for genes of soluble hydrogenase and ribulose-bisphosphate carboxylase, the conjugative plasmids pHG201 and pHG205 were shown to be the carriers of the genetic information for these enzymes. A restriction map of pHG201 for the enzymes AsnI, SpeI, XbaI is presented.

No correlation exists between the conjugative transfer of the autotrophic character and that of plasmids in Nocardia opaca strains.

A new isolate of Nocardia opaca was obtained by enrichment culture for aerobic lithoautotrophic growth on CO2 and H2. This strain, MR22, is very similar to N. opaca MR11 (formerly 1b) in functioning as a donor for genetic information determining the ability to grow lithoautotrophically (Aut character) in matings with Aut- strains of N. opaca or closely related heterotrophic species. The strain contains a plasmid, pHG33 of about 110 kb. A mutant was isolated from strain MR22 which was plasmid-free, and had lost the Aut character, resistance to 50 microM-thallium salt and susceptibility to the nocardia-specific bacteriophage phi B1. As a recipient of the Aut character, this plasmid-free mutant was as well suited as plasmid-bearing Aut- strains of N. opaca. In matings with the mutant as recipient the frequency of Aut+ transconjugants per donor was 3 X 10(-4) with N. opaca MR11 (pHG31-a, Aut+, Tlr, Strs, phi B1s) and 2 X 10(-3) with N. opaca MR22 (pHG33, Aut+, Tlr, Strs, phi B1r) as donor. Phenotypic characterization of the transconjugants, which had been selected for the Aut marker, revealed that in many cases the Aut marker had been transferred without plasmid transfer. Furthermore, plasmid-free, Aut+ transconjugants functioned as donors for the Aut marker. Both plasmid-free and plasmid-bearing transconjugants transferred the Aut marker to the Aut- strains of N. opaca with a frequency which was one or two orders of magnitude higher than that of the wild-type strains. The plasmids pHG31-a and pHG33 code for thallium resistance (50 microM-thallium acetate). The frequency of thallium-resistant transconjugants was 10(-1) to 10(-2) per donor; all thallium-resistant transconjugants contained the donor plasmid. We conclude that the plasmids pHG31-a of strain MR11 and pHG33 of strain MR22 of N. opaca carry the genetic information for thallium resistance but not the Aut character. As plasmid-free Aut+ strains can function as donors the Aut character is assumed to reside on the chromosome and to function as an independent self-transmissible genetic element.