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G Haase

Publications and source records attributed to G Haase.

At least 55 records · Page 3Linked to original sources
PubMed1999

A co-stimulatory signal through ICAM-beta2 integrin-binding potentiates neutrophil phagocytosis.

The beta2 integrin LFA-1 (lymphocyte function associated antigen; CD11a/CD18) is the common ligand for the intercellular adhesion molecules (ICAMs). Integrins support cell function by providing co-stimulatory second signals that are a precondition for full cell activation first described for ICAM-1-binding to LFA-1 in lymphocytes. Integrins can also serve to activate functions associated with distinct subunits of other integrins. In addition to LFA-1, neutrophils express the beta2 integrin Mac-1 (CD11b/CD18; CR3) that apparently contains multiple sites that bind invading microbes directly or through surface-fixed C3, resulting in activation of the phagocyte function. Expression of the LFA-1 counter-receptor ICAM-1 on endothelial cells occurs only at the site of inflammation. Therefore, in neutrophils, ICAM-1 ligand binding could, as with lymphocytes, also play a part as a co-stimulatory signal to induce full phagocytotic function. We show that in neutrophils, the LFA-1 ligand interaction is the stimulatory signal to express full phagocytotic activation. This is best demonstrated by the rapid association of Streptococcus pyogenes with neutrophils, followed by ingestion, strong oxidative-burst induction and enhanced killing of these bacteria, which are well-known for their resistance to human neutrophil defense. These findings may contribute to the development of therapeutic strategies targeting the modulation of ICAM-1-leukocyte interaction.

Antibodies, Monoclonal↗
PubMed1999

Adenoviral vectors for in vivo gene delivery to oligodendrocytes: transgene expression and cytopathic consequences.

Replication defective viral vectors provide a potentially useful means of gene transfer to oligodendrocytes and thus for studying the pathogenesis of white matter disease. In this study we have examined the expression pattern of E1/E3 deleted adenoviral vectors expressing the reporter gene LacZ (AdlacZ) as a means of establishing the value of these vectors for gene delivery to oligodendrocytes in adult rat white matter. Our results indicate that although such an approach can be used to induce transgene expression in oligodendrocytes, it is complicated by both immunogenic and cytopathic effects. Thus, in normal animals, injection of DeltaE1/E3 adenoviral vectors was associated with a robust immune response that led to a lack of expression by 40 days after injection. In order to overcome this complication, virus was injected into the white matter of immuno-deficient athymic rats. These experiments indi- cated that even in the absence of a T cell response high viral titres of DeltaE1/E3 adenoviral vectors had a profound cytopathic effect leading to death of oligodendrocytes and hence demyelination. A similar cytopathic effect was demonstrated using an adenoviral vector expressing the neurocytokine ciliary neurotrophic factor (AdCNTF). As the titre of injected virus was decreased there was a significant decrease in the number of transgene expressing cells. These experiments therefore indicated that in immunodeficient recipients there is a narrow window of virus titre that results in a high rate of infectivity and expression without significant cytopathic consequences. At higher viral titres the cytopathic effects include oligodendrocyte death and demyelination, while at lower titres there is a significant decrease in the efficiency of the number of cells expressing the transgene.

Adenoviridae↗
PubMed1999

Successful treatment of pulmonary Mycobacterium xenopi infection in a natural killer cell-deficient patient with clarithromycin, rifabutin, and sparfloxacin.

Isolation of Mycobacterium xenopi from the respiratory tract may indicate pneumonia, often clinically indistinguishable from tuberculosis. Resistance to the classic antituberculous drugs renders the treatment of these infections problematic. We report on a case of cavernous pneumonia caused by M. xenopi in a 36-year-old male with natural killer cell deficiency but without severe immunodeficiency. He was successfully treated with a novel triple-drug combination comprising clarithromycin, sparfloxacin, and rifabutin. An impressive subsequent regression of pathological pulmonary changes was observed, and mycobacteria could no longer be detected. The therapeutic potential of clarithromycin and sparfloxacin in the treatment of M. xenopi infections is discussed.

Adult↗
PubMed1999

Adenoviral gene therapy of the Tay-Sachs disease in hexosaminidase A-deficient knock-out mice.

The severe neurodegenerative disorder, Tays-Sachs disease, is caused by a beta-hexosaminidase alpha-subunit deficiency which prevents the formation of lysosomal heterodimeric alpha-beta enzyme, hexosaminidase A (HexA). No treatment is available for this fatal disease; however, gene therapy could represent a therapeutic approach. We previously have constructed and characterized, in vitro, adenoviral and retroviral vectors coding for alpha- and beta-subunits of the human beta-hexosaminidases. Here, we have determined the in vivo strategy which leads to the highest HexA activity in the maximum number of tissues in hexA -deficient knock-out mice. We demonstrated that intravenous co-administration of adenoviral vectors coding for both alpha- and beta-subunits, resulting in preferential liver transduction, was essential to obtain the most successful results. Only the supply of both subunits allowed for HexA overexpression leading to massive secretion of the enzyme in serum, and full or partial enzymatic activity restoration in all peripheral tissues tested. The enzymatic correction was likely to be due to direct cellular transduction by adenoviral vectors and/or uptake of secreted HexA by different organs. These results confirmed that the liver was the preferential target organ to deliver a large amount of secreted proteins. In addition, the need to overexpress both subunits of heterodimeric proteins in order to obtain a high level of secretion in animals defective in only one subunit is emphasized. The endogenous non-defective subunit is otherwise limiting.

Adenoviridae↗
PubMed1999

Effect of melanin and carotenoids of Exophiala (Wangiella) dermatitidis on phagocytosis, oxidative burst, and killing by human neutrophils.

The black yeast Exophiala (Wangiella) dermatitidis is an increasingly recognized pathogen and a leading cause of severe pheohyphomycosis. Melanin is thought to contribute to the virulence of E. dermatitidis. Whereas the synthesis and the redox properties of melanin have been studied intensively, the influence of melanin and carotenoids on the phagocytosis, the oxidative burst, and the killing of E. dermatitidis by human neutrophils has not been studied. To study their effects on these phenomena, we applied a combination of flow cytometry and a colony-count-dependent method. Using E. dermatitidis wild-type strain 8565 and several melanin-deficient mutants that have been described previously, we demonstrate that melanin prevents this pathogen from being killed in the phagolysosome of the neutrophils. Melanin did not influence the phagocytosis or the oxidative burst of the neutrophils involved. The carotenoids torulene and torularhodine were not found to contribute to the prevention of killing. The ability of E. dermatitidis to block the effects of the neutrophil oxidative burst may critically impair the potential of the host to sufficiently eliminate this fungal pathogen and thus may play an important role in the pathogenesis of phaeohyphomycosis.

Adult↗
PubMed1999

Identification of genetic determinants for the hemolytic activity of Streptococcus agalactiae by ISS1 transposition.

Streptococcus agalactiae is a poorly transformable bacterium and studies of molecular mechanisms are difficult due to the limitations of genetic tools. Employing the novel pGh9:ISS1 transposition vector we generated plasmid-based mutant libraries of S. agalactiae strains O90R and AC475 by random chromosomal integration. A screen for mutants with a nonhemolytic phenotype on sheep blood agar led to the identification of a genetic locus harboring several genes that are essential for the hemolytic function and pigment production of S. agalactiae. Nucleotide sequence analysis of nonhemolytic mutants revealed that four mutants had distinct insertion sites in a single genetic locus of 7 kb that was subsequently designated cyl. Eight different open reading frames were identified: cylX, cylD, cylG, acpC, cylZ, cylA, cylB, and cylE, coding for predicted proteins with molecular masses of 11, 33, 26, 11, 15, 35, 32, and 78 kDa, respectively. The deduced amino acid sequence of the protein encoded by cylA harbors a conserved ATP-binding cassette (ABC) motif, and the predicted proteins encoded by cylA and cylB have significant similarities to the nucleotide binding and transmembrane proteins of typical ABC transporter systems. Transcription analysis by reverse transcription-PCR suggests that cylX to cylE are part of an operon. The requirement of acpC and cylZABE for hemolysin production of S. agalactiae was confirmed either by targeted mutagenesis with the vector pGh5, complementation studies with pAT28, or analysis of insertion elements in naturally occurring nonhemolytic mutants.

Animals↗
PubMed1999

Rapid identification of Candida glabrata by using a dipstick to detect trehalase-generated glucose.

Candida glabrata is a yeast frequently isolated from human specimens. Based upon its well-known ability to rapidly hydrolyze trehalose, we have developed a novel and cost-effective test incubating one yeast colony emulsified in 50 microl of citrate buffer (0.1 M [pH 5. 0]) containing 4% (wt/vol) trehalose for 3 h at 37 degrees C. Trehalase-generated glucose is detected with a commercially available dipstick (range, 1.0 to 50 g/liter). For evaluation, consecutive clinical isolates and several reference strains of C. glabrata (n = 160), C. albicans (n = 120), and other yeast species with potential ability for utilization of trehalose (C. dubliniensis, n = 11; C. famata, n = 15; C. guilliermondii, n = 5; C. lusitaniae, n = 16; C. parapsilosis, n = 20; C. tropicalis, n = 34; C. viswanathii, n = 5; Pichia angusta, n = 2; C. zeylanoides, n = 2; Saccharomyces cerevisiae, n = 16; C. neoformans, n = 7) were tested. Identification of C. glabrata is achieved within 3 h, with a specificity of 99.1% and a sensitivity of 98.8% when grown on Sabouraud dextrose agar supplemented with 4% glucose.

Candida↗
PubMed1999

Characterization of blood culture isolates of Streptococcus dysgalactiae subsp. equisimilis possessing Lancefield's group A antigen.

For three human blood culture isolates of beta-hemolytic streptococci with Lancefield's serogroup A antigen, phylogenetic analysis of the 16S rRNA genes confirmed biochemical identification as Streptococcus dysgalactiae subsp. equisimilis. Genes encoding M or M-like proteins, which are considered to be major virulence determinants in streptococci, were detected in all of these strains. Our data clearly demonstrate that for beta-hemolytic streptococci, the species assignment should not be based on the results of serogrouping alone.

Aged↗
PubMed1999

Adenoviral cardiotrophin-1 gene transfer protects pmn mice from progressive motor neuronopathy.

Cardiotrophin-1 (CT-1), an IL-6-related cytokine, causes hypertrophy of cardiac myocytes and has pleiotropic effects on various other cell types, including motoneurons. Here, we analyzed systemic CT-1 effects in progressive motor neuronopathy (pmn) mice that suffer from progressive motoneuronal degeneration, muscle paralysis, and premature death. Administration of an adenoviral CT-1 vector to newborn pmn mice leads to sustained CT-1 expression in the injected muscles and bloodstream, prolonged survival of animals, and improved motor functions. CT-1-treated pmn mice showed a significantly reduced degeneration of facial motoneuron cytons and phrenic nerve myelinated axons. The terminal innervation of skeletal muscle, grossly disturbed in untreated pmn mice, was almost completely preserved in CT-1-treated pmn mice. The remarkable neuroprotection conferred by CT-1 might become clinically relevant if CT-1 side effects, including cardiotoxicity, could be circumvented by a more targeted delivery of this cytokine to the nervous system.

Adenoviridae↗
PubMed1999

Therapeutic benefit of ciliary neurotrophic factor in progressive motor neuronopathy depends on the route of delivery.

Ciliary neurotrophic factor (CNTF) has demonstrated therapeutic effects in several mouse mutants with motoneuronal degeneration. However, the poor bioavailability and toxic side effects of recombinant CNTF protein have complicated its use in patients with amyotrophic lateral sclerosis. CNTF gene transfer strategies were developed but faced the question of whether CNTF should be delivered to motoneuron cell bodies or to their axons or muscle targets. To address this issue, we have used an adenoviral vector (AdCNTF) coding for a secretable form of CNTF and compared different routes of its administration in the mouse mutant progressive motor neuronopathy (pmn). Intramuscular, intravenous, and intracerebroventricular injections of AdCNTF or the control vector AdlacZ resulted in transgene expression in skeletal muscle fibers, hepatocytes, and ependymal cells, respectively, as determined by histochemistry and reverse transcription-polymerase chain reaction. AdCNTF intramuscularly treated and intravenously treated pmn mice showed a 25% increase in mean life span and a reduced degeneration of phrenic myelinated nerve fibers, which correlated with elevated CNTF serum bioactivities. In contrast, intracerebroventricular AdCNTF administration did not affect the mean life span or motor axonal degeneration of pmn mice. The differential efficacy of peripheral and central CNTF vector administrations might be of interest for future studies in human motor neuron diseases.

Animals↗
PubMed1998

Gene transfer to Schwann cells after peripheral nerve injury: a delivery system for therapeutic agents.

We transferred a reporter gene to Schwann cells to test whether they might serve as an endoneurial delivery system for therapeutic proteins. A replication-defective adenoviral vector carrying the gene for beta-galactosidase (lacZ) was injected into the distal segment of intact or crushed sciatic nerves of adult rats, and the expression of lacZ was histochemically assessed. Less than 1% of the Schwann cells became reactive in intact nerves, but up to 18% of the proliferating Schwann cells of injured nerves expressed lacZ. Gene expression decayed with time but might persist for up to 2 months. It was enhanced by immunosuppression: daily cyclosporin A injections reduced both proliferation of Schwann cells and lymphocytic infiltration of the nerve, whereas tolerance induced by a single intrathymic injection of the vector 4 days after birth abolished the inflammatory response but not the proliferation of Schwann cells. The vector itself did not impede axonal regeneration. The results indicate that adenoviral gene transfer to Schwann cells in injured nerves is possible and suggest that induced production of neurotrophic factor may represent a therapeutic supplement to surgical nerve repair.

Animals↗
PubMed1998

Discrimination of Bordetella parapertussis and Bordetella pertussis organisms from clinical isolates by PCR using biotin-labelled oligonucleotide probes.

A recently developed shared-primer polymerase chain reaction (PCR) was investigated, in an ongoing pertussis surveillance study for discrimination of Bordetella parapertussis and Bordetella pertussis organisms, by using specific biotin-labelled oligonucleotide probes. From a total of 132 samples, 83 were positive by the B. parapertussis specific probe, 33 were positive by the B. pertussis specific probe and 16 samples containing Hemophilus influenzae as a negative control were below threshold by both probes. The shared-primer PCR in combination with specific oligonucleotide probes provides a rapid, sensitive and specific molecular diagnostic tool for future surveillance studies. In addition, it may be used to further investigate whether B parapertussis antigens should be added to acellular pertussis vaccines to protect against B. parapertussis infections.

Biotin↗
PubMed1998

Neisseria meningitidis serogroup B peritonitis associated with continuous ambulatory peritoneal dialysis.

A case of Neisseria meningitidis peritonitis in a 41-year-old female undergoing continuous ambulatory peritoneal dialysis for end-stage renal failure due to insulin-dependent diabetes mellitus is reported. The bacterial strain was serosubtyped as 4:P1.15, a rarely encountered type. Surprisingly, the minimal inhibitory concentration of vancomycin for the isolate was low (16 mg/l). This may have contributed to the complete recovery of the patient.

Adult↗
PubMed1998

[Methicillin-resistant Staphylococcus aureus (MRSA)--clinical implications].

The isolation rate of MRSA from Staphylococcus aureus infections rose to 8.7% in German hospitals between 1990 and 1995. Patients undergoing surgical treatment or physiotherapy showed a threefold increase in the risk of being colonized or infected with MRSA. Surgical wound infection is the most frequent among MRSA-induced infections (28%). The main transmission path of MRSA inside a hospital is bacterial spread from one patient to another through contact with the hands of nursing staff. Therefore, the crucial strategy in avoiding the spread of bacteria is strict hygiene management through hand disinfection. The most widespread therapeutic regimen for simultaneous eradication of nasal colonization and treatment of infection on other body sites is mupirocin nasal ointment combined with parenteral vancomycin application. The non-indicated use of vancomycin, e.g., for perioperative prophylaxis or prevention of catheter-induced infections, should be avoided, especially after the appearance of vancomycin-intermediately sensitive S. aureus (VISA) strains that have been reported recently from Japan and the USA.

Cross Infection↗