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G Jahn

Publications and source records attributed to G Jahn.

At least 145 records · Page 8Linked to original sources
PubMed1985

Evaluation of plasmids in tetracycline resistant strains of Neisseria gonorrhoeae and Ureaplasma urealyticum in a case of severe urethritis.

A young man who acquired gonococcal urethritis in the Far East was not cured by repeated i.v. treatment with a broad-spectrum penicillin. Cultures of pre- and post-treatment urethral specimens grew tetracycline-resistant penicillinase-producing Neisseria gonorrhoeae (PPNG) and tetracycline-resistant Ureaplasma urealyticum. The patient was successfully treated with erythromycin, to which both isolates were sensitive. The strain of N. gonorrhoeae carried a novel plasmid of 10.5 Md molecular mass in addition to plasmids previously observed in this organism. The strain of U. urealyticum carried two distinct plasmids, one with mass 4.9 Md and the other one with mass 8.1 Md. This report demonstrates that ureaplasmas can contain plasmids and raises the question if tetracycline resistance is controlled by plasmids or by the chromosome.

Adult↗
PubMed1985

A very strong enhancer is located upstream of an immediate early gene of human cytomegalovirus.

A strong transcription enhancer was identified in the genomic DNA (235 kb) of human cytomegalovirus (HCMV), a ubiquitous and severe pathogen of the herpesvirus group. Cotransfection of enhancerless SV40 DNA with randomly fragmented HCMV DNA yielded two SV40-HCMV recombinant viruses that had incorporated overlapping segments of HCMV DNA to substitute for the missing SV40 enhancer. Within HCMV, these enhancer sequences are located upstream of the transcription initiation site of the major immediate-early gene, between nucleotides -118 and -524. Deletion studies with the HCMV enhancer, which harbors a variety of repeated sequence motifs, show that different subsets of this enhancer can substitute for the SV40 enhancer. The HCMV enhancer, which seems to have little cell type or species preference, is severalfold more active than the SV40 enhancer. It is the strongest enhancer we have analyzed so far, a property that makes it a useful component of eukaryotic expression vectors.

Base Sequence↗
PubMed1985

[The so-called dihydralazine hepatitis. A contribution to the pathogenesis].

Liver injuries following application of dihydralazine in 14 patients, ten of them with the typical pattern of perivenous liver cell necrosis, are reported. The other 4 patients, all having been exposed to additional hepatotoxic substances, histologically showed mixed patterns of tissue injury in liver biopsy. Moreover, in 6 of 14 patients there were diseases in the upper abdomen and/or metabolic disorders as well as an exposition to chemical hepatotoxic substances, or an additional application of potential hepatotoxic drugs. 9 of 14 patients had been treated with propranolol and dihydralazine simultaneously. One female patient showed the typical morphologic pattern of 'dihydralazine-damage' after application of propranolol only. In 3 cases with reexposition of dihydralazine merely one of them developed the typical histological behaviour documented in the literature. Distinct fibrosis of the liver remained in 2 cases. Consequently, to the hitherto existing pathogenetic concept of dihydralazine-caused liver injury as a metabolic-toxic-allergic one, there is to be added the new aspect of summing up of the actions of various additional noxious agents.

Adult↗
PubMed1984

The importance and frequency of mixed infections with Chlamydia trachomatis and mycoplasmas in acute gonococcal urethritis.

Chlamydia trachomatis, Ureaplasma urealyticum and Mycoplasma hominis are frequently involved in gonococcal urethritis. We investigated 143 male White and Black patients with gonococcal urethritis (average age 22,5 years). Of these 29% had coexisting Chlam. trachomatis infection, 34% U. urealyticum infection and 13% Mycoplasma hominis infection. Conventional penicillin therapy did not affect Chlam. trachomatis, U. urealyticum or Mycoplasma hominis, which persisted in the lower urogenital tract, causing a so-called 'post-gonococcal urethritis.' Additional therapy with tetracycline or erythromycin was successful in most cases.

Acute Disease↗
PubMed1984

Interleukin-1-like activity constitutively generated by Hodgkin derived cell lines. I. Measurement in a human lymphocyte co-stimulator assay.

Culture supernatants (CS) from Hodgkin derived cell lines have previously been shown to contain colony stimulating activity (CSF) for human cord blood cells, fetal bone marrow and fetal liver cells. In this study 3-day CS from four Hodgkin lines (L428, L538, L540, L591) and two sublines (L428KS, L428KSA) were examined for interleukin (IL) activity. None of the tested CS supported the growth of an IL-2 dependent murine T-cell line, suggesting that the Hodgkin lines do not produce significant amounts of IL-2. When crude 3-day CS from the various lines were assayed for IL-1-activity in the conventional murine thymocyte costimulator assay no or only borderline IL-1-activity was detectable. However, concentrated CS from L428KS exhibited IL-1-activity also in this assay as did lipopolysaccharide (LPS) induced human IL-1. Surprisingly, crude 3-day CS from all Hodgkin cell lines were capable of fully replacing the accessory cell requirement in ConA-induced lymphoproliferation assays of heavily monocyte-depleted human blood lymphocytes. The monocyte-depleted lymphocyte populations were obtained by 1 X g sedimentation at a sedimentation rate of 30.2 to 38.8 mm/hr (fraction IIIa and IIIb). These cells responded poorly to the T-cell mitogen ConA at 10 micrograms/ml and produced no IL-2. Addition of irradiated, autologous monocytes or of CS from the various Hodgkin cell lines quantitatively restored the ConA responsiveness and induced significant IL-2 production in the monocyte-depleted lymphocyte population, suggesting that Hodgkin lines constitutively secrete IL-1 or IL-1-like activity. A preliminary biochemical characterization (heat and pH stability, molecular weight range of 13-24 KD) supports the notion that the accessory cell replacing activity present in CS of Hodgkin cell lines is a type of human IL-1.

Animals↗
PubMed1984

Structure of the transforming region of human cytomegalovirus AD169.

The minimum size fragment of human cytomegalovirus AD169 required to initiate transformation was determined by transfection of primary rat embryo cells with deletion fragments constructed by digestion of a cloned fragment containing the transforming region (pCM4000) with exonuclease III and S1 nuclease. The results indicate that the left-hand boundary of the minimum size sequence for transformation must reside between 490 and 318 bases from the HindIII site of pCM4000. The right-hand boundary was defined by the EcoRI site which is 20 bases from the HindIII site. The nucleotide sequence of the transforming fragment of human cytomegalovirus was determined by the chemical degradation technique of Maxam and Gilbert and with the dideoxynucleoside triphosphate chain termination method. The sequence of pCM4000 comprises 2,848 base pairs and has an A X T composition of 59.5%. Reading frame analysis of the sequence indicated the longest open reading frame was 118 amino acids in length. Northern blot analysis of polyadenylated and non-polyadenylated RNA extracted from cells at immediate early and late times after infection with human cytomegalovirus indicate that one 5.0-kilobase RNA species hybridized to pCM4000 (Jahn et al., J. Virol, in press). The direction of transcription was determined by hybridization of this transcript with M13 single-stranded probes, and S1 analysis of this RNA did not detect introns.

Base Sequence↗
PubMed1984

Predominant immediate-early transcripts of human cytomegalovirus AD 169.

Transcription of the human cytomegalovirus genome (strain AD 169) was investigated at the immediate-early (IE) time after infection, by using cycloheximide to suppress virus-specific protein synthesis. In total cell RNA, four predominant IE transcripts were found which were encoded by one contiguous region of the long unique segment between map units 0.06 and 0.16 in prototype arrangement of human cytomegalovirus AD 169 DNA. Analysis by Northern blot hybridizations demonstrated that the transcripts possessed a size of 1.9, 2.2, 2.3, and 5.0 kilobases, respectively. Coding sequences and directions of transcriptions were mapped by Northern blots and hybridizations with oligodeoxythymidylic acid-primed and randomly primed cDNA. The 1.9-, 2.2-, and 2.3-kilobase RNAs were found in the polyadenylated fraction of IE RNA exclusively; in contrast, a part of the 5.0-kilobase RNA appeared polyadenylated, although the majority of the same transcript was found in the nonpolyadenylated pool. Also, different from the other IE genes, the DNA coding for the 5.0-kilobase IE RNA was transcribed in high quantities during the late phase of virus replication, suggesting an exemption from the temporal regulation of herpesvirus transcription.

Base Sequence↗
PubMed1983

[Demonstration of a tetracycline-resistance factor in a genital Mycoplasma strain. Clinical and molecular biology aspects of Ureaplasma coinfected penicilliń and tetracycline-resistant gonorrhea].

We report a male patient with severe penicillin-resistant gonococcal urethritis, coinfected with a tetracycline resistant strain of ureaplasma urealyticum. Ureaplasmas are frequently involved in gonococcal urethritis and commonly this organism may persist after the penicillin therapy causing a "post-gonoccal-urethritis" (PGU). Additional treatment with tetracyclines prove to be successful in most of these patients except in cases of tetracycline resistance in ureaplasma urealyticum. In a case like this erythromycin may be useful, a drug to which these isolates are sensitive. The microbiological and genetic feature of a tetracycline resistant strain of ureaplasma urealyticum is presented in detail. The clinical and epidemiological importance of these results are discussed and compared with the literature.

Adult↗
PubMed1983

[Gonorrheal urethritis--frequently a mixed Chlamydia and Mycoplasma infection. Results in 143 male patients with acute gonorrhea].

Chlamydia trachomatis, Ureaplasma urealyticum and Mycoplasma hominis are frequently demonstrated in cases of acute gonorrhoeic urethritis. Among 143 males (average age 22.5 years) Chlamydia was demonstrated in 29%, U. urealyticum in 34% and M. hominis in 13%. Penicillin treatment of gonorrhoea does not affect Chlamydia and Mycoplasma so that these organisms will persist in the lower urogenital tract. Generally postgonorrhoeic urethritis is associated with Chlamydia or Mycoplasma infection. Nearly all patients were cured by tetracyclin or erythromycin administration. Incidence and complications of gonorrhoea co-infected with Chlamydia and Mycoplasma should be taken into account in its diagnosis and treatment.

Adolescent↗
PubMed1983

[Incidence of posthepatic sequelae of acute viral hepatitis C].

There are not yet any ascertained results concerning the prognosis of the non-A/non-B hepatitis not depending on transfusion. In an identical source of infection meanwhile several working teams in the GDR by means of long-term observations for three years control groups of women able to propagate who were incubated by a hepatitis C-virus (of the non-A/non-B group of the hepatotropic viruses), so that first evidence on posthepatitic sequelae after hepatitis C is possible. Of 115 women who were treated with anti-D-globulin contaminated with C virus 57 women fell ill (= 49.5%). Of them 39 patients (3 68.4%) were cured after 3 years, 7 patients (6 12.3%) showed the signs of a residual hepatitis, 10 patients (3 17.5%) showed a chronically persisting and 1 patient (= 1.75%) a chronically active hepatitis. The results presented are compared to those of other working teams of our country.

Acute Disease↗
PubMed1981

Origin of Haemophilus influenzae R factors.

The Haemophilus influenzae R plasmids specifying resistance against one, two, or three antibiotics which have emerged in different parts of the world were shown to have closely related but not identical plasmid cores. The gene for ampicillin resistance in the H. influenzae plasmid pKRE5367 is part of a transposon similar to Tn3, which was transposed from pKRE5367 onto RSF1010 in Escherichia coli. An indigenous H. influenzae plasmid (pW266) was isolated. Its properties correspond to those of the H. influenzae R plasmids, except for the presence of a drug resistance transposon. The in vitro-generated H. influenzae R plasmids carrying an ampicillin resistance transposon, a tetracycline resistance transposon, and a transposon for combined tetracycline-chloramphenicol resistance resembled the natural isolates. The findings support the hypothesis that the R plasmids of H. influenzae are of multiclonal evolutionary origin.

Ampicillin↗
PubMed1979

Molecular characterization of a small Haemophilus influenzae plasmid specifying beta-lactamase and its relationship to R factors from Neisseria gonorrhoeae.

The ampicillin-resistant Haemophilus influenzae strain Ve445 which caused purulent meningitis and septicaemia in a newborn child in Germany contained a 4.4 megadalton (Mdal) plasmid (pVe445) and produced a TEM type beta-lactamase. The transformation to ampicillin resistance of a sensitive Escherichia coli strain with isolated pVe445 DNA proved that the structural gene for the beta-lactamase resided on this plasmid genome. Molecular DNA-DNA hybridization studies and electron microscope DNA heteroduplex analysis indicated that pVe445 probably contained 38 to 41% of the ampicillin translocation DNA segment (TnA) found on R factors of enteric origin. The TnA fragment present in pVe445 most likely does not contain both of the inverted repeat sequences of TnA. DNA-DNA polynucleotide sequence studies indicated that the 4.4 Mdal plasmid pVe445 was unrelated to the 30 to 38 Mdal H. influenzae R plasmids but was closely related to the 4.1 Mdal ampicillin resistance specifying H. influenzae plasmid RSF0885 isolated in the U.S.A. The H. influenzae plasmid pVe445 shared 91% of its base sequences with the beta-lactamase specifying Neisseria gonorrhoeae plasmid pMR0360 (4.4 Mdal) and had 85% of its base sequences in common with the beta-lactamase specifying N. gonorrhoeae plasmid pMR0200 (3.2 Mdal). All of the four 3.2 to 4.4 Mdal beta-lactamase specifying R plasmids of H. influenzae and N. gonorrhoeae investigated probably have a common evolutionary origin.

Ampicillin↗
PubMed1979

Molecular nature of two Haemophilus influenzae R factors containing resistances and the multiple integration of drug resistance transposons.

The 36-megadalton Haemophilus influenzae R plasmid pHK539 was found to specify resistance to tetracycline (Tc) and ampicillin (Ap). It was shown by molecular hybridization studies and by electron microscopy that the plasmid pHK539 contained the tetracycline translocation deoxyribonucleic acid (DNA)segment (TnTc) as well as the ampicillin translocation segment (TnAp). The TnAp was integrated in the stem of TnTc. The 34-megadalton H. influenzae R plasmid pRI234 carried a translocatable DNA segment which specified both tetracycline and chloramphenicol (Cm) resistance. Self-annealing and DNA-DNA heteroduplex experiments indicated that this transposon is probably composed of TnTc containing an insertion of a chloramphenicol resistance transposon (TnCm). TnCm is inserted into one of the components of the TnTc inverted repetitions and is itself flanked on both sides by long inverted repetitions. The H. influenzae plasmids pHK539 and pRI234 had more than 60% of their polynucleotide sequences in common with all the other 30- to 40-megadalton R factors recently found in H. influenzae isolates from different countries. The tetracycline-chloramphenicol resistance transposon of pRI234 was integrated twice at different sites in the plasmid after its growth in medium containing tetracycline. The presence of the two copies of the transposon was correlated with higher minimum inhibitory concentrations against tetracycline as well as against chloramphenicol. After its growth in medium containing tetracycline, the H. influenzae R plasmid pFR16017 specifying Tc resistance contained one, two, three, or even four copies of TnTc integrated at different sites in the plasmid, or the loop of TnTc was amplified. The heterogeneity of the pFR16017 plasmid was seen in all single-colony isolates and correlated with a higher minimum inhibitory concentration against tetracycline.

Ampicillin↗
PubMed1978

[Infectious resistance to antibiotics in Haemophilus influenzae (author's transl)].

Ampicillin-resistant Haemophilus influenzae does occur now in the FRG. In one isolate a plasmid with resistance genes (R-factor) could be demonstrated as cause of the ampicillin resistance. This R-factor influences production of a beta-lactamase of the TEM type which destroys ampicillin. The infectious nature of the ampicillin resistance was proven by the fact that it was transferable to other bacterial species through cocultivation. Parallel to ampicillin resistance tetracycline resistant Haemophilus influenzae has occurred in the FRG. Here the resistance was equally bound to plasmids. These R-factors are infectious as well. Molecular analysis of the 3 isolated resistance factors in Haemophilus influenzae showed that they carry the same resistance genes which are known from R-factors of Enterobacteriaceae. In the therapy of purulent infections due to Haemophilus influenzae such as childhood meningitis one can no longer rely on general ampicillin sensitivity of the offender. Apart from ampicillin and tetracycline resistant Haemophilus influenzae chloramphenicol resistance has been observed in a few cases.

Ampicillin↗
PubMed1978

Molecular properties of transmissible R factors of Haemophilus influenzae determing tetracycline resistance.

The tetracycline-resistant Haemophilus influenzae strains LU121 and FR16017, recently isolated in West Germany, each harbour a plasmid; that of the former (pLU12U) has a mol. wt of 31.5 X 10(6) and that of the latter (pFR16017) has a mol. wt of 33 X 10(6). Conjugation and DNA-DNA hybridization studies have shown that both plasmids are self-transmissible and carry tetracycline-resistance genes. The purified plasmid DNA of H. influenzae strain LU121 transformed a sensitive Escherichia coli strain to tetracycline resistance. The two R factors are closely related to the H. influenzae plasmid specifying ampicillin resistance (pKRE5367). Electron microscope DNA heteroduplex analysis indicated that pLU121 and pFR15017 probably carry the tetracycline-resistance transposon TnD and that pKRE5367 probably carries the ampicillin-resistance transposon TnA. There is more than one integration site for the insertion which probably represents TnD in pFR15017. All three plasmids have a similar plasmid core and could have a common evolutionary origin.

DNA, Bacterial↗