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Biomedical subjects

U Gross

Publications and source records attributed to U Gross.

At least 37 records · Page 2Linked to original sources
PubMed2002

Molecular, immunological, enzymatic and biochemical studies of coproporphyrinogen oxidase deficiency in a family with hereditary coproporphyria.

A 27-year-old woman who had recurrent pain in renal bed since 1998 with increasing character, was stationary admitted. The patient showed dark urine, complained of hair loss and took since 1994 a hormonal oral contraceptive. No photosensitivity was observed. Determinations of urinary porphyrin metabolites in 1998 revealed a porphyria cutanea tarda like excretion pattern with elevations of uro- (1767 nmol/24 hr, normal <29 nmol/24 hr) and heptacarboxyporphyrin (568 nmol/24 hr; normal <4 nmol/24 hr). Follow-up studies in feces showed the characteristics of a hereditary coproporphyria with dominance of coproporphyrin isomer III (total= 1470 nmol/g, isomer III= 93%), (normal: <37 nmol/g, isomer III = 25-35%). The excretion of porphyrin precursors (delta-aminolevulinic acid and porphobilinogen) was increased by taking an ethinylestradiol-cyproteronacetate-preparation, but acute and/or chronic manifestations were not observed. Coproporphyrinogen oxidase activity was decreased to 35% in the patient (normal=138+/-21 pkat/g protein; x+/-s), whereas the activity of red cell uroporphyrinogen decarboxylase was normal. Her mother and both sisters could be verified as heterozygous gene carriers of hereditary coproporphyria by their urinary and fecal excretion parameters and because of reduced coproporphyrinogen oxidase activity up to 50%. The father was normal with respect to his genotype. Molecular analysis revealed a hitherto unknown mutation with the transversion of a cytosine to thymine at nucleotide position 854 in exon 4 of the coproporphyrinogen oxidase gene. The gene defect was confirmed by DGGE in the mother and her three daughters. The investigation of the immunological nature of the defective coproporphyrinogen oxidase gene from the whole family revealed decreased concentrations of coproporphyrinogen oxidase protein in the patient, her mother and her two sisters.

Adult↗
PubMed2001

Toxoplasma gondii down-regulates MHC class II gene expression and antigen presentation by murine macrophages via interference with nuclear translocation of STAT1alpha.

The obligate intracellular protozoan parasite Toxoplasma gondii is able to establish persistent infections within human and animal hosts. We have shown recently that T. gondii down-regulates IFN-gamma-induced MHC class II expression in murine bone marrow-derived macrophages (BMM4). As shown in this study, the capacity of IFN-gamma-activated murine BMMphi to present ovalbumin to CD4+ T cell hybridomas was dose-dependently inhibited by T. gondii. IFN-gamma-induced up-regulation of H2-Aa, H2-Ab, H2-Eb, H2-Ma, H2-Mb, H2-Oa and invariant chain transcripts was prominently down-regulated by T. gondii. Furthermore, mRNA levels of class II transactivator and interferon-regulatory factor-1 were significantly diminished. Electromobility shift assays demonstrated a decrease in the binding activity of nuclear extracts to the IFN-gamma-activated site after infection with T. gondii, indicating parasitic interference with IFN-gamma-induced signaling. However, neither the expression of the IFN-gammaR nor the IFN-gamma-induced tyrosine phosphorylation of IFN-gammaR alpha chain and signal transducer and activator of transcription (STAT) 1alpha was diminished by T. gondii. IFN-gamma-induced nuclear translocation of STAT1alpha was nevertheless inhibited after infection as demonstrated by immunofluorescence microscopy and subcellular fractionation analyses. In conclusion, this novel mechanism of microbial interference with MHC class II gene expression may contribute to intracellular survival and establishment of persistent infection with T. gondii.

Active Transport, Cell Nucleus↗
PubMed2001

Multicenter evaluation of strategies for serodiagnosis of primary infection with Toxoplasma gondii.

The diagnostic performance of single-serum assays for toxoplasma-specific immunoglobulin (Ig)M. IgA. IgG, and IgE antibodies and of different combinations of such antibody assays in 20 European reference centers was assessed. A panel of 276 sera, of which 73 came from patients who seroconverted within 3 months (acute infection), 49 from patients who had seroconverted 3-12 months earlier (convalescence), and 154 from subjects who had two IgG-positive samples obtained 12 months apart (past infection), was tested with 20 toxoplasma-antibody assays and 195 combinations. In general, every assay with high diagnostic sensitivity showed low diagnostic specificity, i.e. no assay performed alone could reliably distinguish acute from past infection. Furthermore, no single assay (or combination) could separate convalescence from the other stages of toxoplasma infection. However, excellent diagnostic performances were reached by sequential use of highly sensitive IgM assays and methods examining IgG avidity or stage specificity. IgA or IgM assays were less suitable for confirmation of toxoplasma-IgM positivity. This study documents the strength of test combinations in assessing the stage of toxoplasma infection.

Acute Disease↗
PubMed2001

[Madreporic hydroxyapatite granulates for filling bone defects].

Two macrocrystalline madreporic granular hydroxyapatite implants of different size range (single crystal size within both implants 1-3 microns) were implanted for 7, 28, 84 and 168 days into the trabecular bone of the distal femur epiphysis of rabbits. Both materials were investigated histologically. For testing of granular materials a new animal model has been developed. The drill hole was closed by reimplantation of an autologeous chondrocortical tissue slice to prevent loss of particles into the knee-joint. Both of the granular materials tested developed increasing bone bonding from the 7th day on to outer surfaces and pore surfaces. The degradation of both of the materials affected the superficial implant layers in soft-tissue interfaces exclusively and was mainly due to passive processes, e.g. leaching, fragmentation of granules after crack-production, particulate degradation and subsequent phagocytosis of liberated implant particles by macrophages and foreign body giant cells. Zones of superficial implant degradation were bonded partially to bone a second time. A possible low-degree, active superficial degradation by foreign body giant cells is discussed. Osteoclasts of typical morphology as being observed on other hydroxyapatite implant surfaces were not demonstrated. This was related to the low degradation rate of the implants. Both of the granular materials tested are useful in filling bone defects. A guided tissue regeneration due to partial implant degradation and subsequent bone formation seems to be impossible since the degradation rate of the materials is too low.

Animals↗
PubMed2001

Transcriptional profile of Toxoplasma gondii-infected human fibroblasts as revealed by gene-array hybridization.

To investigate the host-cell response to infection with the obligate intracellular pathogen Toxoplasma gondii, the transcriptional profiles of infected and uninfected human fibroblasts (HFF) were determined by hybridization to gene arrays representing nearly 600 genes. Transcripts that displayed a greater than five-fold increase in level relative to uninfected controls were also examined by RT-PCR and Northern analysis, resulting in the identification of 13 genes that were strongly up-regulated after infection with T. gondii. Comparisons with the transcriptional profiles of fibroblasts infected with Salmonella typhimurium and Chlamydia trachomatis allowed the identification of genes which are specifically induced in T. gondii-infected cells. While most of the up-regulated genes were induced on infection with all three pathogens, the genes for the transferrin receptor and MacMARCKS were up-regulated in Toxoplasma-infected fibroblasts only. Expression of the transferrin receptor protein was examined by Western analysis and found to be specifically elevated in Toxoplasma-infected fibroblasts. Genes which are specifically induced in T. gondii-infected cells are particularly interesting for further studies, since they might be used to dissect specific interactions of this pathogenic parasite with its host cell.

Animals↗
PubMed2001

Intracellular protozoan parasites and apoptosis: diverse strategies to modulate parasite-host interactions.

Programmed cell death (apoptosis) is an important regulator of the host's response during infection with a variety of intracellular protozoan parasites. Parasitic pathogens have evolved diverse strategies to induce or inhibit host-cell apoptosis, thereby modulating the host's immune response, aiding dissemination within the host or facilitating intracellular survival. Here, we review the molecular and cell-biological mechanisms of the pathogen-induced modulation of host-cell apoptosis and its effects on the parasite-host interaction and the pathogenesis of parasitic diseases. We also discuss the previously unrecognized phenomenon of apoptotic cell death in (unicellular) protozoan parasites and its potential implications.

Animals↗
PubMed2001

Survival of two patients with severe delta-aminolaevulinic acid dehydratase deficiency porphyria.

The course of delta-aminolaevulinic acid dehydratase activity was studied over the 23 years in erythrocytes of two male patients. The enzyme activity was originally 1-2%, which then increased to approximately 8%, of normal levels several years after clinical manifestation of the acute hepatic porphyria syndrome. Urinary excretions of delta-aminolaevulinic acid and coproporphyrin III were excessively increased in the two patients with compound-heterozygous delta-aminolaevulinic acid dehydratase deficiency porphyria.

Adolescent↗
PubMed2001

Human neutrophils produce macrophage inhibitory protein-1beta but not type i interferons in response to viral stimulation.

Several cell types have been shown to produce type I interferons (IFN). Of human leukocytes, monocytes and especially type 2 dendritic cell precursors (pDC2) seem to be the main producers and also have a wide spectrum of cytokine production. However, neutrophils seem to have a limited capacity for cytokine production but possess efficient defense mechanisms vs. bacterial infection by phagocytosis and degranulation. To determine whether they also have antiviral functions, IFN-alpha and IFN-beta were measured in preparations of pure neutrophils. The capacity of neutrophils to produce type I IFN is controversial. Additionally, macrophage inflammatory protein-1alpha (MIP-1alpha) and MIP-1beta were measured, as they are described to have indirect or direct antiviral activity. As stimulants, active and inactivated Newcastle disease virus (NDV), Sendai virus, and granulocyte colony-stimulating factor (G-CSF) were used. Peripheral blood mononuclear cells (PBMC) from the same donors were highly reactive to viral stimulation, whereas neutrophils failed to produce IFN but produced MIP-1beta in response to NDV. We conclude that neutrophils fail to prevent viral infection by IFN production but probably possess alternative mechanisms, such as secreting MIP-1beta in response to viruses.

Cells, Cultured↗
PubMed2001

Use of recombinant mitogillin for improved serodiagnosis of Aspergillus fumigatus-associated diseases.

During human infection, Aspergillus fumigatus secretes a 18-kDa protein that can be detected as an immunodominant antigen in the urine of infected patients. Recently, this protein was shown to be mitogillin, a ribotoxin that cleaves a single phosphodiester bond of the 29S rRNA of eukaryotic ribosomes. We proved the immunogenic capacity of mitogillin in a rabbit animal model, indicating its usefulness as an antigen for serological diagnosis of invasive aspergillosis. The mitogillin gene from A. fumigatus was transferred from plasmid pMIT+ to expression vector pQE30 and expressed in Escherichia coli as a fusion protein. Purified recombinant mitogillin was recognized by serum immunoglobulin G (IgG) of polyclonal rabbit sera that were obtained by immunization with purified native mitogillin. Consequently, we developed an enzyme-linked immunosorbent assay for detection of IgG, IgM, and IgA antibodies to recombinant mitogillin. In serum samples of patients suffering from aspergilloma (AO; n = 32), invasive pulmonary aspergillosis (IPA; n = 42), or invasive disseminated aspergillosis (IDA; n = 40), a good correlation of production of IgG antibody against mitogillin and clinical disease was observed (for patients with AO, 100% [32 of 32] were positive; for patients with IPA, 64% [31 of 42] were positive; for patients with IDA, 60% [24 of 40] were positive). In contrast, positive titers for serum IgG and IgM antibodies against mitogillin were found in only 1.3% of the serum samples of healthy volunteers and positive titers for IgA antibody were found in only 1.0% of the serum samples of healthy volunteers (n = 307; specificity = 95.4%). These results indicate that recombinant mitogillin expressed in E. coli can be used for improvement of the serodiagnosis of A. fumigatus-associated diseases.

Adolescent↗
PubMed2001

Inhibition of host cell apoptosis by Toxoplasma gondii is accompanied by reduced activation of the caspase cascade and alterations of poly(ADP-ribose) polymerase expression.

The obligate intracellular protozoan parasite Toxoplasma gondii has been shown to protect different cell types from apoptosis induced by a variety of pro-apoptotic treatments. However, the precise cell biological mechanisms of this inhibition remained unknown. As shown in this study, apoptosis in human-derived HL-60 and U937 cells induced by treatment with actinomycin D or TNF-alpha in combination with cycloheximide, respectively, was indeed dose-dependently downregulated by prior infection with T. gondii, as determined by DNA fragmentation assays. Cleavage of caspase 3 and caspase 9 after treatment with pro-apoptotic stimuli was considerably diminished by T. gondii. Furthermore, release of mitochondrial cytochrome c during apoptosis in HL-60 cells was prevented by intracellular parasites and this was correlated with the absence of DNA strand breaks on the single cell level. Inhibition of cytochrome c release coincided with a twofold upregulation of Mcl-1 protein levels in HL-60 and U937 cells, while Bcl-2 expression did not increase after infection. Parasitic interference with the caspase cascade led to a reduced proteolytic cleavage of the nuclear target molecule protein kinase C delta. In parallel, poly(ADP-ribose) polymerase protein levels were prominently downregulated by T. gondii, irrespective of whether HL-60 and U937 cells had been treated with pro-apototic stimuli or left untreated. However, poly(ADP-ribose) polymerase mRNA levels remained unchanged after infection as determined by RT-PCR analyses. These observations suggest that T. gondii has evolved different mechanisms that may contribute to downregulation of host cell apoptosis, namely inhibition of cytochrome c release and subsequent caspase activation as well as downregulation of poly(ADP-ribose) polymerase protein levels.

Animals↗
PubMed2001

Induction of interleukin-8 in human neutrophils after MHC class II cross-linking with superantigens.

Neutrophils have been shown to express major histocompatibility complex class II (MHC II) after stimulation. However, reports concerning the functional effect of MCH II expression are still lacking. In our hands, granulocyte-monocyte colony-stimulating factor (GM-CSF) alone and in combination with interferon (IFN)-gamma, but not IFN-gamma or interleukin (IL)-3, induced a significant level of expression of human leukocyte antigen DR on neutrophils. The addition of staphylococcal enterotoxin E to neutrophils resulted in a significant increase in IL-8 production only after prestimulation with GM-CSF alone or in combination with IFN-gamma but had no effect on neutrophils preincubated with IFN-gamma alone or IL-3. Staphylococcal enterotoxin A, another bivalent superantigen, also stimulated production of IL-8 by preincubated polymorphonuclear neutrophils, whereas staphylococcal enterotoxin A mutants that are not able to cross-link MHC II molecules failed to induce IL-8 production. Taken together, our results clearly demonstrate that after induction of MHC II, neutrophils are able to respond to MHC II-specific stimulation. These findings support the ideas that the induced MHC II complex is completely functional and that neutrophils may be able to present antigens.

Enterotoxins↗
PubMed2000

Evaluation of calcium phosphates and experimental calcium phosphate bone cements using osteogenic cultures.

In this study, rat bone marrow cells (RBM) were used to evaluate two biodegradable calcium phosphate bone cements and bioactive calcium phosphate ceramics. The substances investigated were: two novel calcium phosphate cements, Biocement F and Biocement H, tricalcium phosphate (TCP), surface-modified alpha-tricalcium phosphate [TCP (s)] and a rapid resorbable calcium phosphate ceramic consisting of CaKPO(4) (sample code R5). RBM cells were cultured on disc-shaped test substrates for 14 days. The culture medium was changed daily and also examined for calcium, phosphate, and potassium concentrations. Specimens were evaluated using light microscopy, and morphometry of the cell-covered substrate surface, scanning electron microscopy, and energy dispersive X-ray analysis and morphometry of the cell-covered substrate surface. Areas of mineralization were identified by tetracyline labeling. Except for R 5, rat bone-marrow cells attached and grew on all substrate surfaces. Of the different calcium phosphate materials tested, TCP and TCP (s) facilitated osteoblast growth and extracellular matrix elaboration to the highest degree, followed by Biocements H and F. The inhibition of cell growth encountered with R 5 seems to be related to its high phosphate and potassium ion release.

Absorbable Implants↗
PubMed2000

High-throughput scanning of the rat genome using interspersed repetitive sequence-PCR markers.

We report the establishment of a hybridization-based marker system for the rat genome based on the PCR amplification of interspersed repetitive sequences (IRS). Overall, 351 IRS markers were mapped within the rat genome. The IRS marker panel consists of 210 nonpolymorphic and 141 polymorphic markers that were screened for presence/absence polymorphism patterns in 38 different rat strains and substrains that are commonly used in biomedical research. The IRS marker panel was demonstrated to be useful for rapid genome screening in experimental rat crosses and high-throughput characterization of large-insert genomic library clones. Information on corresponding YAC clones is made available for this IRS marker set distributed over the whole rat genome. The two existing rat radiation hybrid maps were integrated by placing the IRS markers in both maps. The genetic and physical mapping data presented provide substantial information for ongoing positional cloning projects in the rat.

Animals↗
PubMed2000

Perfluorocarbons useful tools for medicine.

Perfluorocarbons (PFCs) combine rather unique chemical and physical properties together with physiological inertness. Due to this, they have become useful tools in medicine. Whereas the majority of applications benefit from their excellent oxygen solubility, there are several applications making use of other PFC properties. The great importance of PFC ultra-purity is especially emphasized.

Animals↗
PubMed2000

Fixed lingual arch appliance for compliance-free unilateral molar distalization in the mandible. Three case studies.

An asymmetrically activated lingual arch appliance enables rapid, unilateral molar distalization in the mandible without active patient compliance. Using the segmented arch technique, the biomechanics involve only the tooth moved, in accordance with the 2-tooth concept, with a large, multi-rooted tooth segment acting as an anchoring unit. The anchorage system requires no maxillary involvement.

Activator Appliances↗