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Biomedical subjects

M Metzger

Publications and source records attributed to M Metzger.

At least 19 recordsLinked to original sources
PubMed1995

Mutual adaptation of bacteriophage fd, pfd plasmids and their host strains.

The synthetic plasmid pfdC1 with the replication origin of phage fd and fd gene 2 grows autonomously in E. coli cells. DNA sequencing revealed several mutations compared to the fd genome causing reduced expression of viral gene 2 protein, which can be toxic for the host cell. Another adaptation was noticed for E. coli strains with a copy of fd gene 2 on the F-episome and a pfdA-plasmid with a minimal fd replication origin, when maintained at 42 degrees C. The carrier cells adjusted their cellular metabolism to these stress conditions, whereas replication functions of the plasmid or expression of fd gene 2 on the F-episome were not changed. The filamentous bacteriophages tend to reduce their genome size into miniphages, which was also observed for phages with an antibiotic resistance gene. Bacteriophages with a transposon insertion in the viral gene 2 had a tendency to restore the mutated gene by exchange with the functional gene 2 carried in recA-host cells. Mobilization of pfd-plasmids with RP4 transfer functions was reduced due to interference of replication and transfer in the rolling circle mode. The vectors used in these studies can also be applied as cloning vectors, which are compatible with many other plasmid vectors.

Adaptation, Physiological↗
PubMed1995

[The belly-board technic for the sparing of the small intestine. Studies on positioning accuracy taking into consideration conformational irradiation technics].

BACKGROUND: The immobilization error of patients positioned on the open table-top device in prone position as well as the movement of the small bowel out of the pelvis by this positioning technique was determined. The positioning error is of special importance for the 3-dimensional treatment planning for conformational radiotherapy. PATIENTS AND METHODS: The positioning error was determined by superpositioning 106 portal films with the corresponding simulator films from 21 patients with carcinoma of the rectum who-received 3D-planned conformational radiotherapy (3-field technique with irregular blocks). The movement of the small bowel out of the pelvis was studied by comparing simulator films after barium swallow in supine and open table-top position as well with 3D-treatment plans of the same patient in both positions in 3 cases. RESULTS: The positioning error along the medio-lateral, dorso-ventral and cranio-caudal axis was 1.4/0.6/1.8 mm and the standard deviation 4.4/6.8/6.3 mm, respectively. In comparison to the supine position more rotation errors in the sagittal view were observed (37% and 9% respectively) with a median of 5.1 degrees. Six out of 22 patients showed no adhesions of the small bowel and a complete movement out of the treatment field was achieved. 14 out of 16 Patients with adhesions revealed a partial movement of the small bowel out of the treatment field. Comparing 3D-treatment plans in both positions again demonstrated a marked reduction of the irradiated small bowel volume with the use of the open table-top device. CONCLUSIONS: The open table-top device positioning technique is a simple and cheap positioning support to reduce small bowel obstructions by radiation therapy of pelvic and retroperitoneal tumors. For the radiation treatment planning the data suggest a safety margin to compensate positioning errors of approximately 1.5 cm referring to the 95% confidence interval.

Administration, Oral↗
PubMed1994

Acute responses of non-human primates to airway delivery of an adenovirus vector containing the human cystic fibrosis transmembrane conductance regulator cDNA.

Recombinant human adenovirus (Ad) vectors are leading candidates for human gene therapy for cystic fibrosis (CF) based on demonstration of efficient transfer of exogenous genes to rodent respiratory epithelium in vivo and human respiratory cells in vitro. The safety of Ad-mediated gene transfer to the respiratory epithelium and acute (up to 21 days) clinical responses to airway delivery of a replication-deficient recombinant, E1-, E3- Ad type 5-based vector containing the human cystic fibrosis transmembrane conductance regulator cDNA (AdCFTR) were evaluated in rhesus monkeys. Airway delivery of an Ad vector with the lacZ marker gene demonstrated beta-galactosidase expression in epithelial cells. Animals administered intratracheal AdCFTR demonstrated human CFTR cDNA expression in airway epithelial cells. Animals administered AdCFTR intranasal, and 24 hr later, intrabronchial [2 x 10(7) to 5 x 10(10) plaque-forming units (pfu), n = 12], in a fashion similar to a proposed human protocol, or only intrabronchial (10(11) pfu, n = 3), had no significant changes in clinical parameters compared to vehicle controls (n = 6). Microscopic analysis of the lung by necropsy or bronchoalveolar lavage demonstrated a dose-dependent increase in inflammatory cells, primarily lymphocytes, in the area where AdCFTR was delivered, which persisted for at least 2 months in some animals. Serum anti-Ad type 5 neutralizing antibody titers did not rise and shed Ad was not detected. The presence of AdCFTR DNA, analyzed by the polymerase chain reaction (PCR), was not detected in organs outside the lung. These data demonstrate that AdCFTR is well tolerated in non-human primates, although there is dose-dependent inflammation in the lung not clinically apparent.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenoviruses, Human↗
PubMed1994

Genetics of galactose metabolism of Erwinia amylovora and its influence on polysaccharide synthesis and virulence of the fire blight pathogen.

Galactose metabolism mutants of Erwinia amylovora were created by transposon insertions and characterized for their growth properties and interaction with plant tissue. The nucleotide sequence of the galE gene was determined. The gene, which encodes UDP-galactose 4-epimerase, shows homology to the galE genes of Escherichia coli, Neisseria gonorrhoeae, Rhizobium meliloti, and other gram-negative bacteria. Cloned DNA with the galE and with the galT and galK genes did not share borders, as judged by the lack of common fragments in hybridization with chromosomal DNA. These genes are thus located separately on the bacterial chromosome. In contrast to the gal operon of E. coli, the galE gene of E. amylovora is constitutively expressed, independently of the presence of galactose in the medium. The function of the galE gene but not of the galT or galK gene is required for bacterial virulence on pear fruits and seedlings. In the absence of galactose, the galE mutant was deficient in amylovoran synthesis. Subsequently, the galE mutant cells elicited host defense reactions, and they were not stained by fluorescein isothiocyanate-labelled lectin, which efficiently binds to amylovoran capsules of E. amylovora. The mutation affected the side chains of bacterial lipopolysaccharide, but an intact O antigen was not required for virulence. This was shown with another mutant, which could be complemented for virulence but not for side chain synthesis of lipopolysaccharide.

Amino Acid Sequence↗
PubMed1992

Site-directed and transposon-mediated mutagenesis with pfd-plasmids by electroporation of Erwinia amylovora and Escherichia coli cells.

The suicide plasmid pfdA31-Tn5 was constructed to mutagenize Erwinia amylovora and Escherichia coli strains by electorporation. This vector carries the bacteriophage fd replication origin, a beta-lactamase gene and the transposon Tn5. For propagation the plasmid depends on host cells producing fd gene-2 protein. Electroporation of E.amylovora or E.coli cells with plasmid pfdA31-Tn5 yielded more than 10(4) transposition events per micrograms DNA. We have produced and characterized transposon mutants of E.amylovora affecting either galactose metabolism or the synthesis of the phytotoxin (L)-2,5-dihydrophenylalanine. A Tn5-insertion in a gene, involved in exopolysaccharide synthesis of E.amylovora strain Ea7/74, was subcloned into vector pfdA31 and used to mutagenize E.amylovora strain Ea1/79 by site-directed recombination.

Blotting, Southern↗
PubMed1992

Adenovirus-mediated in vivo gene transfer and expression in normal rat liver.

Replication deficient, recombinant adenovirus (Ad) vectors do not require target cell replication for transfer and expression of exogenous genes and thus may be useful for in vivo gene therapy in hepatocytes. In vitro, primary cultures of rat hepatocytes infected with a recombinant Ad containing a human alpha 1-antitrypsin cDNA (Ad-alpha 1AT) synthesized and secreted human alpha 1AT for 4 weeks. In rats, in vivo intraportal administration of a recombinant Ad containing the E. coli lacZ gene, was followed by expression of beta-galactosidase in hepatocytes 3 days after infection. Intraportal infusion of Ad-alpha 1AT produced detectable serum levels of human alpha 1AT for 4 weeks. Thus, targeted gene expression has been achieved in the liver, albeit at low levels, suggesting that adenovirus vectors may be a useful means for in vivo gene therapy in liver disorders.

Adenoviruses, Human↗
PubMed1992

The effect of aerosolized recombinant human granulocyte macrophage colony-stimulating factor on lung leukocytes in nonhuman primates.

The number and function of myeloid cells in the lungs are critical determinants of health and disease. To examine whether these cells can be modulated in vivo by a colony-stimulating factor (CSF), recombinant human granulocyte macrophage-CSF (GM-CSF) was given to cynomolgus monkeys by either continuous intravenous infusion (7,200 U/kg/day) for 2 wk or by aerosol exposure to 10(7) U on 1 or 2 consecutive days. At intervals after the initiation of GM-CSF administration, animals underwent bronchoalveolar lavage (BAL) and had peripheral blood sampled to characterize changes in lung and circulating phagocytic cells. Compared with animals exposed to bovine serum albumin, there was an increase in the total number of BAL cells retrieved. This increase was greatest in animals receiving aerosolized GM-CSF, and it was the result of more macrophages and neutrophils. Both lung macrophages and blood neutrophils from animals exposed to aerosolized GM-CSF exhibited an augmented respiratory burst in response to phorbol myristate acetate. Lung macrophages from GM-CSF-exposed animals exhibited increased capacity to bind and/or ingest opsonized and unopsonized Staphylococcus aureus. Despite functional activation of lung phagocytic cells, biochemical analyses of BAL fluid for markers of lung injury revealed an increase in only some parameters in the GM-CSF group. Intravenous administration of GM-CSF had the expected effect on augmenting the number of myeloid cells in the bloodstream. Aerosolized GM-CSF produced a transient effect on circulating myeloid cell number between 3 and 5 days after exposure.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Inhalation↗
PubMed1991

Amplification of three threonine biosynthesis genes in Corynebacterium glutamicum and its influence on carbon flux in different strains.

The hom-thrB operon (homoserine dehydrogenase/homoserine kinase) and the thrC gene (threonine synthase) of Corynebacterium glutamicum ATCC 13,032 and the homFBR (homoserine dehydrogenase resistant to feedback inhibition by threonine) alone as well as homFBR-thrB operon of C. glutamicum DM 368-3 were cloned separately and in combination in the Escherichia coli/C. glutamicum shuttle vector pEK0 and introduced into different corynebacterial strains. All recombinant strains showed 8- to 20-fold higher specific activities of homoserine dehydrogenase, homoserine kinase, and/or threonine synthase compared to the respective host. In wild-type C. glutamicum, amplification of the threonine genes did not result in secretion of threonine. In the lysine producer C. glutamicum DG 52-5 and in the lysine-plus-threonine producer C. glutamicum DM 368-3 overexpression of hom-thrB resulted in a notable shift of carbon flux from lysine to threonine whereas cloning of homFBR-thrB as well as of homFBR in C. glutamicum DM 368-3 led to a complete shift towards threonine or towards threonine and its precursor homoserine, respectively. Overexpression of thrC alone or in combination with that of homFBR and thrB had no effect on threonine or lysine formation in all recombinant strains tested.

Carbon↗
PubMed1989

Pharmacokinetic and distribution analysis of variant forms of tissue-type plasminogen activator with prolonged clearance in rat.

Human tissue-type plasminogen activator (t-PA) is a glycoprotein used currently in thrombolytic therapy. Because of its rapid half-life (T1/2) of approximately five minutes, intravenous (IV) infusion of large doses (approximately 100 mg) are required in patients treated for myocardial infarction. To identify the determinant(s) on t-PA responsible for such rapid clearance, metabolically labeled forms of recombinant t-PA were analyzed in rats following IV administration. The following seven forms of t-PA were tested: (a) natural or glycosylated wild-type t-PA; (b) nonglycosylated wild-type t-PA; (c) delta F t-PA, which lacks the fibronectin fingerlike domain; (d) delta E t-PA, which lacks the epidermal growth factor (EGF) domain; (e) delta FE t-PA, which lacks both the finger and EGF domains; (f) delta FE3X t-PA, a form of delta FE t-PA in which Asn-linked glycosylation is prevented at all known glycosylation sites (Asn-117, 184, and 448; replaced by Gln); and (f) delta FE1X t-PA, a form of delta FE t-PA in which high-mannose-type glycosylation is prevented at Asn-117. Both glycosylated and nonglycosylated wild-type t-PA cleared in an exponential biphasic manner, with an initial alpha-phase T1/2 of 0.8 and 1.9 minutes, respectively. This result demonstrates that carbohydrate is not the primary mediator of the rapid clearance of t-PA. The liver was the primary organ responsible for uptake of these molecules. All other proteins tested, except for delta E t-PA, demonstrated primarily monophasic clearance patterns with T1/2 ranging between 12 and 27 minutes, and reduced uptake in the liver. delta E t-PA however, cleared in a biphasic manner with an alpha-phase T1/2 of 2.1 minutes. Results presented suggest that the clearance of t-PA is mediated by two distinct mechanisms. The primary determinant(s) responsible for modulating the rapid clearance of t-PA appears to be resident within the polypeptide sequence encoding the finger and/or EGF domains, with emphasis on the finger domain. A second and less significant contribution to clearance is defined by the presence and type of glycosylation.

Animals↗
PubMed1988

Human IL-3 and GM-CSF act synergistically in stimulating hematopoiesis in primates.

Interleukin-3 (IL-3) is a member of a family of growth factors, each of which supports the proliferation and development of hematopoietic precursors in culture. Although the biologic effects of the different hematopoietic growth factors have been well documented in different culture systems, it has only recently become possible to study the activities of these molecules in vivo. In comparison with the later acting hematopoietic growth factors granulocyte-macrophage colony-stimulating factor (GM-CSF) and granulocyte colony-stimulating factor, IL-3 elicited a delayed and relatively modest leukocytosis when continuously infused intravenously in primates. The IL-3 infusion, however, greatly potentiated the responsiveness of the animal to subsequent administration of a low dose of GM-CSF. These results suggest that IL-3 expands an early cell population in vivo that subsequently requires the action of a later acting factor such as GM-CSF to complete its development. Optimal stimulation of hematopoiesis may be achieved with combinations of hematopoietic growth factors.

Animals↗
PubMed1988

A new chromosomal instability disorder confirmed by complementation studies.

Two sisters with a complex clinical pattern, including microcephaly, microgenia, defects of skin pigmentation, anal stenosis/atresia, and combined immunodeficiency together with spontaneous chromosomal instability and cellular hypersensitivity to X-rays and bleomycin are described. Complementation studies on heterokaryons proved that the underlying genetic defect is non-allelic with that of patients with ataxia telangiectasia (complementation groups AB-E) and the Nijmegen breakage syndrome, but identical with the case described by Conley et al. (1986).

Ataxia Telangiectasia↗
PubMed1987

[Subperiosteal metastasis of esophageal adenocarcinoma].

The authors report an observation of a tibial subperiosteal metastasis of an esophageal cancer. Subperiosteal metastases are rare, appearing on plain radiography as a cortical lysis of a long bone with a "saucer" aspect. They were considered specific of a bronchogenic carcinoma. To the best of our knowledge this is the second observation of subperiosteal metastasis, whose primary tumor is not a broncho-pulmonary cancer.

Adenocarcinoma↗
PubMed1986

[Effect of adjuvant immunoglobulin therapy on infections in patients in an surgical intensive care unit. Results of a randomized controlled study].

A randomized controlled clinical trial was conducted on the effects of immunoglobulin in therapy for infections in 104 intensive care patients. At the first sign of infection, one group of 50 patients received an i.v. preparation of immunoglobulin (4 X 100 ml) combined with antibiotics. The other 54 control patients received antibiotics alone. The most common infections in these patients were pneumonia, septicemia, peritonitis and wound sepsis. Infections were significantly seldom the cause of death, especially in patients with high-risk surgery who had been treated with immunoglobulin (p less than or equal to 0.05). Likewise ventilation time in the high-risk surgery group averaged only 5.5 days for those receiving immunoglobulin as opposed to 12.7 days in controls (p less than or equal to 0.01). Whereas the control group, in particular patients with pneumonia, remained in intensive care an average of 21.5 days, those receiving immunoglobulin stayed only 14.8 days (p less than or equal to 0.01). In general, patients treated with immunoglobulin recovered more rapidly from infections than did controls (p less than or equal to 0.01).

Adult↗
PubMed1984

Pharmacological properties of the new orally active angiotensin converting enzyme inhibitor 2-[N-[(S)-1-ethoxycarbonyl-3-phenylpropyl]-L-alanyl] -(1S,3S,5S)-2-azabicyclo[3.3.0]octane-3-carboxylic acid (Hoe 498).

2-[N-[(S)-1-Ethoxycarbonyl-3-phenylpropyl]-L-alanyl]-(1S,3S,5S) - 2-azabicyclo[3.3.0]octane-3-carboxylic acid (Hoe 498) can be characterized as a novel orally active non-sulfhydryl containing angiotensin converting enzyme inhibitor. Designed as a prodrug to improve the bioavailability Hoe 498 has to be deesterified to its active moiety Hoe 498-diacid to develop full inhibitory potency. The present study compares the basic pharmacological properties of Hoe 498 in rats and dogs to those of enalapril. In vitro assays revealed equal potency of both Hoe 498-diacid and enalaprilat. In vivo the inhibitory potency was judged by the ability to attenuate the pressor response induced by angiotensin I. The results indicate that Hoe 498 was approximately 10 times more potent than enalapril after oral intake in conscious rats or after intraduodenal administration in anaesthetized rats, whereas after intravenous injection both compounds exhibited equal potency. Hoe 498 was at least twice as potent as enalapril after oral or intraduodenal administration in dogs but about 4 times more potent than enalapril after intravenous injection. In conclusion, the obtained data point to a prodrug pathway for Hoe 498 which should be advantageous with regard to bioavailability, onset and duration of action and therefore promises to be favourable in the treatment of different cardiovascular diseases.

Angiotensin I↗
PubMed1984

Administration of antithymocyte serum to syphilitic rabbits inhibits development of resistance to reinfection with Treponema pallidum.

Three groups of female rabbits were inoculated i.v. with T. pallidum. One group of the animals was treated with horse anti-rabbit thymocyte serum (ATS) one day before and during the next two weeks after infection. Two other groups, one treated with normal horse serum (NHS) in the same way as the previous one and the other untreated, served as controls. After various time intervals, all the animals were tested for the content of T and B lymphocytes in the peripheral blood, humoral (VDRL and TPI tests), and cell-mediated (SDH test) responses. Two days after testing, animals of each group were challenged i.d. with T. pallidum, and observed for appearance of syphilitic lesions. The treatment of syphilitic rabbits with ATS caused a significant reduction in the number of T lymphocytes and a distinct inhibition of development of cell-mediated immunity associated with the lack of resistance to reinfection with T. pallidum till the 16th week of the infection; the level of B lymphocytes and the development of serological responsiveness was not affected by ATS treatment. The results are interpreted as indicating the protective role of cell-mediated immunity in syphilis.

Animals↗
PubMed1984

Enriched immune T cell suspension protects rabbits against infection with Treponema pallidum.

Four groups of rabbits were given intravenously (i.v.) enriched T or B lymphocytes derived from normal or immunized donor rabbits; 24 hrs later, all these animals were infected intradermally (i.d.) with T. pallidum in order to check their immune status. Only rabbits which received immune T cells showed a state of resistance to infection with T. pallidum, whereas recipients of lymphocytes of three other groups did not.

Animals↗