Biomedical subjects

A Neubauer

Publications and source records attributed to A Neubauer.

At least 109 records · Page 6Linked to original sources

PubMed1998

Optimizing frequency and number of controls for automatic multichannel analyzers.

Sampling strategy fundamentally influences the effectiveness of quality control with control charts. This study shows a simple approach for optimizing the control strategy for automatic multichannel analyzers that takes into account cost-efficiency considerations. Our main focus is on the frequency of controls necessary. The methods used are based on a field study (on a Hitachi/BM 747), the views of experts, and computer simulations of customary cost-models together with a survey of the literature. We found that industrial cost-models are applicable only with distinct limitations, but-unlike the test-yield model-they offer consistent solutions. On the basis of the field study and the opinions of experts, we adjusted the control strategy to account for inadequacies in the theoretical models. The combined result is that, for effective operation, the number of samples between controls may reach values up to 100 and should not require controls more often than every 30 samples on comparable multichannel analyzers. For adequate statistical performance, a simple 3-SD Shewhart chart usually requires not more than two controls of the same material at each time.

Autoanalysis↗

PubMed1998

[An unusual course of low-malignancy non-Hodgkin lymphoma of the stomach].

We report on a 51-year-old women, who suffered from a low-grade lymphoma of the stomach (MALT-lymphoma) and underwent subtotal gastrectomy in 1991. Two years later she developed a relapse of her MALT-lymphoma. She was treated with two Helicobacter pylori eradication therapies which led to complets remission of the lymphoma. In 1994 she developed a high-grade conchal lymphoma and underwent conchotomy. No moleculargenetic evidence of any relationship between the two lymphomas was found.

Amoxicillin↗

PubMed1997

Equine herpesvirus 1 mutants devoid of glycoprotein B or M are apathogenic for mice but induce protection against challenge infection.

Equine herpesvirus 1 (EHV-1) mutants devoid of the open reading frames (ORFs) of either glycoprotein (g) B or M were constructed and tested for their immunogenic potential in a murine model of EHV-1 infection. The mutant viruses were engineered using the virulent EHV-1 strain RacL11 or the modified live vaccine strain RacH by inserting the Escherichia coli LacZ gene into the viral ORFs. RacL11-infected mice showed signs typical of an EHV-1 infection, whereas mice infected with the EHV-1 gB- or gM-negative mutants or with RacH did not develop disease. No difference in the pathogenic potential of RacL11 gB- and gM-negative viruses was observed after application of either phenotypically completed or negative viruses. However, revertant RacL11 viruses in which the gB or gM gene had been restored caused EHV-1-related symptoms that were indistinguishable from those induced by RacL11. Mice that had been immunized with phenotypically negative gB- and gM-deficient EHV-1 were challenged with the RacL11 virus 25 days after immunization. Mock-immunized mice developed EHV-1 disease and high virus loads in their lungs were observed. In contrast, mice developed not exhibit EHV-1-caused disease. It was concluded (i) that deletion of either gB or gM abolished the virulence of strain RacL11 and (ii) that immunization with gB- or gM-negative EHV-1 elicited a protective immunity that was reflected by both virus-neutralizing antibodies and EHV-1-specific T-cells in spleens of immunized mice.

Animals↗

PubMed1997

Cure of Helicobacter pylori infection and duration of remission of low-grade gastric mucosa-associated lymphoid tissue lymphoma.

BACKGROUND: Low-grade B-cell lymphomas arising in mucosa-associated lymphoid tissue (MALT) are most frequently localized in the gastrointestinal tract. More than 90% of gastric MALT lymphomas are diagnosed in patients with chronic, Helicobacter pylori-associated gastritis. High remission rates for these lymphomas have been observed after the cure of H. pylori infection. Data are lacking, however, with regard to the duration of the remissions. To address this question of remission duration, we have followed 50 patients in whom H. pylori infections were eradicated, and we determined whether the patients in complete remission displayed evidence of residual monoclonal B cells during follow-up. METHODS: Patients were treated with amoxycillin and omeprazole for 2 weeks in an attempt to cure H. pylori infections. Follow-up included endoscopic investigations with biopsy sampling. Monoclonal B cells in biopsy specimens were detected by means of a polymerase chain reaction (PCR)-based assay. RESULTS: H. pylori infections were cured in all 50 patients. The median follow-up for the 50 patients is currently 24 months (729 days; range, 135-1411 days). Forty patients achieved complete remission of their lymphomas, but five have subsequently relapsed. The median time of continuous complete remission for the 40 patients was 15.4 months (468 days; range, 0-1198 days). Among six patients whose Iymphomas did not respond to H. pylori eradication, four revealed high-grade lymphomas upon surgery. PCR indicated the presence of monoclonal B cells during follow-up in 22 of 31 assessable patients in complete remission. CONCLUSIONS: Complete remissions of low-grade gastric MALT Iymphomas after the cure of H. pylori infection appear to be stable, although most patients display evidence of monoclonal B cells during follow-up. Whether these patients are truly cured of their Iymphomas remains to be determined.

Adult↗

PubMed1997

Synthesis and processing of the equine herpesvirus 1 glycoprotein M.

In a previous report, the function of the equine herpesvirus 1 (EHV-1) glycoprotein M (gM) homolog was investigated. It was shown that EHV-1 gM is involved in both virus entry and direct cell-to-cell spread of infection (N. Osterrieder et al., J. Virol. 70, 4110-4115, 1996). In this study, experiments were conducted to analyze the synthesis, posttranslational processing, and the putative ion channel function of EHV-1 gM. It was demonstrated that EHV-1 gM is synthesized as an Mr 44,000 polypeptide, which is cotranslationally N-glycosylated to an Mr 46,000-48,000 glycoprotein. The Mr 46,000-48,000 gM moiety is processed to an Mr 50,000-55,000 glycoprotein, which is resistant to treatment with endoglycosidase H, indicating that processing occurs in the Golgi network. EHV-1 gM forms a dimer in infected cells and the virion, as was demonstrated by the presence of an Mr 105,000-110,000 gM-containing band in electrophoretically separated lysates of infected cells and purified extracellular virions. The Mr 105,000-110,000 protein band containing gM was also observed in lysates of cells that had been transfected with EHV-1 gM DNA. The translation of EHV-1 gM is initiated at the first in-frame methionine of the gM open reading frame as shown by transient transfection experiments of full-length gM and a truncated gM lacking the aminoterminal 83 amino acids. Functional expression of EHV-1 gM in Xenopus laevis oocytes together with voltage-clamp analyses demonstrated that gM per se does not exhibit ion channel activity as had been speculated from the predicted structure of the polypeptide.

Animals↗

PubMed1997

Analysis of the contributions of the equine herpesvirus 1 glycoprotein gB homolog to virus entry and direct cell-to-cell spread.

Experiments to analyze the functions of the equine herpesvirus 1 (EHV-1) glycoprotein gB were performed. Cell lines which stably expressed either the full-length EHV-1 gB or only the extracellular portion of gB (amino acids 1 to 844) were constructed and were termed TCgBf and TCgB delta, respectively. Using the cell line TCgBf, a gB-negative viral mutant, L11delta gB, was generated by replacing a 2.1-kb BglII-NruI fragment in the EHV-1 strain RacL11 gB with the Escherichia coli LacZ gene. EHV-1 strain RacL11, the modified live vaccine strain RacH, and L11delta gB were used for functional studies. It was shown that: (i) EHV-1 gB is essential for virus growth in vitro since gB-negative L11delta gB exhibited titers of <10 PFU/ml when grown and titrated on noncomplementing cells. (ii) The cell line expressing truncated gB (TCgB delta) did not complement for the growth of L11delta gB, but the RacH virus grew to titers comparable to those of RacL11 in all cell lines tested. Since RacH had amino acids 944-980 of gB replaced by 7 missense amino acids as determined by nucleotide sequence analysis, the extreme carboxyterminus but not a domain between amino acid residues 845 and 943, probably the transmembrane domain, of EHV-1 gB is dispensable for virus growth in cultured cells. (iii) Single infected cells but no plaque formation were observed after infection of noncomplementing cells with L11delta gB, demonstrating the requirement of EHV-1 gB for direct cell-to-cell spread of infection. (iv) The attachment of gB-negative L11delta gB virions to target cells was similar to both phenotypically complemented L11delta gB and parent RacL11 virus. (v) L11delta gB viral titers could be enhanced by using the fusogen polyethylene glycol (PEG). The increase of L11delta gB titers by PEG treatment, however, was considerably lower compared to gB-negative pseudorabies virus, suggesting that EHV-1 gB might not be as stringently required for virus penetration as are its homologs in other Alphaherpesvirinae.

Amino Acid Sequence↗

PubMed1997

What role does Helicobacter pylori eradication play in gastric MALT and gastric MALT lymphoma?

The concept of mucosa-associated lymphoid tissue (MALT) has been introduced to differentiate biological functions from behavior of nonnodal vs. nodal lymphoid tissues. Lymphomas arising from MALT also behave differently than typical nodal lymphomas. In contrast to other tissues, MALT in the stomach is almost exclusively a result of Helicobacter pylori infection. Thus, MALT is part of the host defense against the pathogen H. pylori. Consequently, lymphomas arising from gastric MALT may be a clonal evolution starting from the infection. In low-grade gastric MALT lymphoma, cure of the infection may induce complete histological remission in the majority of patients. Investigators have recently reported that complete remission rate is between 70% and 80%. In an extended analysis, we have treated 84 patients with low-grade gastric MALT lymphoma in stage El, using a dual regimen to eradicate H. pylori. Complete remission was observed in 68 (80%) patients; a partial remission was found in 4 patients. In contrast, 12 patients showed no change and were referred to alternative treatment. In patients in complete remission, a polymerase chain reaction assay for the rearranged immunoglobulin heavy-chain gene remained positive in many cases. Together with data from the literature, these data suggest that the majority of patients with low-grade gastric MALT lymphomas in stage El respond to eradication of H. pylori. Longer follow-up investigations are necessary to determine if remissions indicate a cure from the disease.

Gastric Mucosa↗

PubMed1997

Staphylococcal exoproducts down-regulate cyclooxygenase 1 and 2 in peritoneal macrophages.

Peritoneal macrophages (PMOs) are important components of the host defense against microbial infection in patients undergoing continuous ambulatory peritoneal dialysis (CAPD). Incubation of human PMOs with cell-free supernatant (BFS), prepared from Staphylococcus aureus, inhibited prostaglandin E2 (PGE2) and thromboxane B2 (TXB2) production. Slot-blot analysis of cyclooxygenase-1 (Cox-1) and Cox-2 demonstrated a decrease in both Cox-1 (29%) and, to a greater extent, Cox-2 (65%) protein expression after BFS stimulation. When competitive polymerase chain reaction (PCR) was used, the peak levels of Cox-1 and Cox-2 messenger ribonucleic acid (mRNA) in unstimulated PMOs were 0.304+/-0.13 pmol/L and 9.61+/-2.84 pmol/L (mean+/-SEM, n = 3), respectively. After exposure of samples to BFS for 30 minutes, the level of Cox-2 mRNA was reduced to 0.59+/-0.449 pmol/L (16-fold reduction, p < 0.05), and the level of Cox-1 mRNA was reduced to 0.02+/-0.002 pmol/L (15-fold reduction, p < 0.05). In contrast, these same PMOs showed an increased expression of IL-6 mRNA and increased secretion of IL-6 protein. These results indicate that prostaglandin production in PMOs is regulated by alterations in both immunoreactive Cox-1 and Cox-2. The down-regulation of Cox metabolism in these cells is primarily related to the delayed and depressed increase in the Cox-2 gene product.

Adolescent↗

PubMed1997

CLIP-115, a novel brain-specific cytoplasmic linker protein, mediates the localization of dendritic lamellar bodies.

Intracellular localization of organelles may depend in part on specific cytoplasmic linker proteins (CLIPs) that link membranous organelles to microtubules. Here, we characterize rat cDNAs encoding a novel, brain-specific CLIP of 115 kDa. This protein contains two N-terminal microtubule-binding domains and a long coiled-coil region; it binds to microtubules and is homologous to CLIP-170, a protein mediating the binding of endosomes to microtubules. CLIP-115 is enriched in the dendritic lamellar body (DLB), a recently discovered organelle predominantly present in bulbous dendritic appendages of neurons linked by dendrodendritic gap junctions. Local microtubule depolymerization leads to a temporary reduction of DLBs. These results suggest that CLIP-115 operates in the control of brain-specific organelle translocations.

Amino Acid Sequence↗

PubMed1997

The status of p53 in the metastatic progression of colorectal cancer.

In order to investigate the role of TP53 in tumour progression and metastasis, we analysed 33 liver metastases of colorectal carcinomas and 19 primary colon carcinomas from the same hospital with respect to mutational changes, loss of heterozygosity and expression of the TP53 tumour suppressor gene. Direct sequencing of PCR products corresponding to the coding region of TP53 revealed that 13 of 19 primary tumours (68%) and 23 of 33 liver metastases (70%) had mutations in the TP53 gene. The distribution of mutations along the coding region of TP53 was similar in liver metastases compared to primary tumours. Thus, codon specificity did not seem to be a relevant factor and cells carrying specific TP53 mutations seem to have no selective advantage in the metastasising process. Comparing our data with the mutational spectra found in other countries did not reveal differences in the distribution of mutations along the coding region. Most of the metastases analysed showed loss of heterozygosity (LOH, 9 of 12 cases, 75%) and strong nuclear staining in immunohistochemistry (10 of 17 cases, 59%). Furthermore, with respect to mRNA expression levels, tumours carrying TP53 mutations showed significantly higher p53 mRNA levels compared to those without TP53 mutations. Thus, regulation of p53 mRNA levels seems to be subject to selection processes in tumourigenesis.

Chromosome Deletion↗

PubMed1997

Gastric MALT-lymphoma and Helicobacter pylori infection.

The presence of lymphoid tissue in the gastric mucosa is virtually pathognomonic of Helicobacter pylori infection. This lymphoid tissue has mucosa-associated lymphoid tissue (MALT) characteristics suggesting that H. pylori infection may represent a stimulus for the growth of gastric MALT lymphoma. H. pylori can be detected in more than 90% of patients with low-grade gastric MALT lymphoma supporting the aetiological role of the organism. The strongest evidence for the significance of H. pylori in the pathogenesis of low aetological-grade gastric MALT lymphoma is provided by clinical studies showing that cure of H. pylori infection is followed by a complete regression of these tumours in most patients. This paper reviews the current knowledge about antibacterial treatment of low-grade gastric MALT lymphoma, and immunological and molecular aspects in the pathogenesis of the disease.

Anti-Bacterial Agents↗

PubMed1997

Underestimation of inversion (16) in acute myeloid leukaemia using standard cytogenetics as compared with polymerase chain reaction: results of a prospective investigation.

In order to determine whether the polymerase chain reaction (PCR) is more suitable for the detection of inversion (16) as compared with standard cytogenetics, we prospectively investigated a total of 132 cases of de novo acute myeloid leukaemia (AML) (n = 121) and secondary AML after myelodysplastic syndromes (MDS) (n = 11) using a sensitive and nested PCR procedure to detect the fusion transcripts CBFbeta-MYH11. All patients were recruited within 10 months in an ongoing multicentre AML-trial. In addition, several cases from a retrospective molecular analysis were included. The data were compared with standard cytogenetics performed in a central laboratory. Of the 132 prospective AML cases, five patients (3.7%) harboured inv(16) upon conventional cytogenetics. In all cases fusion transcripts CBFbeta-MYH11 were detected using PCR. In addition in two patients fusion transcripts were detected, although cytogenetics revealed a normal karyotype. In the group of patients analysed retrospectively, four patients harboured fusion transcripts specific for CBFbeta-MYH11; cytogenetics were normal in one case, and could not be evaluated in two cases. These data show that PCR may be a better means to detect inv(16) in AML. Since inv(16) may have prognostic impact in AML, detection of this aberration seems important in the clinical management of AML patients.

Acute Disease↗

PubMed1997

Regression of gastric MALT lymphoma after eradication of Helicobacter pylori is predicted by endosonographic staging. MALT Lymphoma Study Group.

BACKGROUND & AIMS: Recent studies suggest that eradication of Helicobacter pylori may result in complete regression of low-grade lymphoma of the gastric mucosa-associated lymphoid tissue (MALT). Which patients benefit from this treatment is unknown. The aim of this study was to prospectively study whether staging by echoendoscopy predicts the outcome of treatment of MALT lymphoma by eradication of H. pylori. METHODS: Twenty-two patients positive for H. pylori with low-grade gastric B-cell MALT lymphoma were examined by echoendoscopy at the time of diagnosis. Treatment for H. pylori consisted of a 2-week course of oral omeprazole and amoxicillin. Patients were followed up by endoscopy and biopsy. RESULTS: H. pylori was eradicated in all patients. Complete regression of MALT lymphoma was observed in 12 patients (54%), partial regression in 5 patients (23%), and no response in 5 patients (23%) during follow-up. Twelve of 14 patients with lymphoma restricted to the mucosa or submucosa (stage E-I1) at echoendoscopy, but none of the 10 patients with higher stage (P < 0.01), showed complete regression of MALT lymphoma. In stage E-I1 patients, the probability of complete regression of lymphoma was 60% at 6, 79% at 12, and reached 100% at 14 months, respectively. CONCLUSIONS: Staging of gastric low-grade MALT lymphomas by endoscopic ultrasonography allows prediction of the response to therapy by eradication of H. pylori.

Adult↗

PubMed1997

Is the polymerase chain reaction or cure of Helicobacter pylori infection of help in the differential diagnosis of early gastric mucosa-associated lymphatic tissue lymphoma?

PURPOSE: The differential diagnosis of early gastric mucosa-associated lymphatic tissue (MALT) lymphoma based on Helicobacter pylori gastritis may be difficult when lymphoepithelial lesions are not detected. The aim of the present study was to investigate the question whether the polymerase chain reaction (PCR) or cure of H pylori infection may be of help in this respect. PATIENTS AND METHODS: Twenty patients with suspected low-grade gastric MALT lymphomas were treated in a double-blinded, randomized, crossover trial with 2,250 mg of either amoxicillin or placebo, both in combination with omeprazole, for 14 days with the aim to cure H pylori infection. PCR was performed using primers specific for the CDR3 region to detect monoclonal B cells. RESULTS: In five of 20 patients, MALT lymphomas were finally diagnosed. Three of these five patients went into complete remission, while two were referred to surgery. In the 15 patients with gastritis, complete regression was observed in all cases. With respect to PCR, monoclonal bands were detected in all four of the analyzed lymphoma patients before histology showed lymphoma. In addition, monoclonal bands were found in three patients with gastritis. In the patients with gastritis and monoclonal PCR, complete regression took longer as compared with the remaining 12 patients with polyclonal PCR and gastritis (P = .0209). Successful H pylori eradication was associated with earlier diagnosis of the MALT lymphoma (P = .0237). CONCLUSION: CDR3-PCR may be of help in the differential diagnosis of early gastric MALT lymphoma. Furthermore, H pylori eradication may lead to earlier diagnosis.

Adult↗

PubMed1997

Recent progress on the role of Axl, a receptor tyrosine kinase, in malignant transformation of myeloid leukemias.

Receptor tyrosine kinases (RTK) play an important role in the signal transduction of normal and malignant cells. There are different families of RTKs which are mainly characterized by differences in the ligang-binding extracellular domains. Axl (or UFO/Ark) is the first member of a new class of RTK with two fibronectin type III domains and two immunoglobulin-like domains present at the extracellular domain. The axl-gene has been isolated by means of gene transfection studies using DNA of patients with chronic myelogeneous leukemia. For a previous and the present study, we used a sensitive reverse-transcriptase polymerase chain reaction assay to detect axl's mRNA in cells from normal and malignant hematopoietic tissue. Axl's mRNA expression was mainly detected in myelo-monocytic cells, whereas much weaker transcription was seen in lymphatic cells and in lymphatic leukemias. In normal bone marrow, axl was heavily transcribed in marrow stromal cells. Further, we analysed Axl protein expression using monoclonal antibody M50 in peripheral stem cell harvests; in most harvests, no co-expression of CD34 and Axl was detected. However, in one patient with AML in complete remission, Axl was co-expressed on 80% of the CD34-positive population. These data show that axl is preferentially expressed in monocytes and stromal cells. Furthermore, a fraction of CD34-positive progenitor cells may express Axl. The exact mechanism for transformation of myeloid progenitor cells through Axl, however, remains to be determined.

Flow Cytometry↗

PubMed1997

Allele-specific PCR amplification of factor V Leiden to identify patients at risk for thromboembolism.

Resistance to activated protein C is the most common hereditary cause of thrombophilia and is significantly linked to factor V Leiden. We designed primers in order to identify factor V Leiden by allele-specific PCR amplification. Amplification specificity for factor V was ensured by a 3' primer located at the intron 9/exon 10 border of the gene. One sense and two antisense primers were used in two separate primer mixes specific for factor V ARG506 (wild-type) or factor V GLN506 (factor V Leiden). In each PCR reaction a pair of primers amplifying a fragment of the human growth hormone gene was included as an internal positive amplification control. The presence or absence of specific PCR amplification allowed definite allele assignment without the need for any postamplification specificity step. The internal positive control primers indicate a successful PCR amplification, allowing the assignment of homozygosity. In a prospective study 126 patients with thromboembolic events were analyzed using this technique and PCR-RFLP. The concordance between these methods was 100%. In 27 patients a heterozygous factor V GLN506 mutation was detected, whereas 1 patient with recurrent thromboembolism was homozygous. No false-positive or false-negative results were observed in the homozygous as well as heterozygous samples. Additionally, in 15 samples identified to carry the point mutation by allele-specific PCR amplification, automatic sequencing has confirmed the heterozygous or homozygous point mutation. Due to its time- and cost-saving features allele-specific amplification should be considered for screening of factor V Leiden.

Alleles↗

PubMed1997

[Molecular epidemiology of Candida infections in HIV-infected mothers and their offspring].

In a prospective study 15 consecutive children and 12 HIV-infected mothers were examined according to their colonization with Candida species in the oral cavity and on the hands. From 39 samples a total of 49 Candida isolates could be recovered (26 C. albicans, 4 C. glabrata, 9 Rhodotorula rubra, 4 C. dubliniensis, 3 C. tropicalis, 2 C. famata, 1 S. cerevisiae). Antifungal susceptibility testing revealed fluconazole MICs from 0.09 microgram/ml to 100 micrograms/ml. Genotyping was done with an AP-PCR technique using the primer "M13" and "(GACA)4". From the mycologic culture identical yeast isolates were found in 10 families. However, with PCR typing identical findings were seen only in 5 families. A C. albicans isolate resistant to fluconazole in vitro was found in a child and the mother of the same family. It could be summarized that yeast strains are transmitted between HIV infected mothers and their children. With PCR typing diversity among yeast isolates could be demonstrated even between members of the same family.

Acquired Immunodeficiency Syndrome↗

PubMed1996

The equine herpesvirus 1 IR6 protein influences virus growth at elevated temperature and is a major determinant of virulence.

The diploid IR6 gene (ORF 67) of equine herpesvirus type 1 (EHV-1) is absent in the modified live EHV-1 vaccine strain RacH and is present in a mutated form in the avirulent EHV-1 strains RacM24 and RacM36, such that the IR6 protein fails to form the typical rod-like structures observed for wild-type EHV-1 RacL11. To assess the role of the IR6 protein in EHV-1 replication and virulence, two recombinant RacH viruses, HIR6-1 and HIR6-2, that harbor a single copy of the wild-type IR6 gene were engineered and characterized. It was shown that: (i) HIR6-1 or HIR6-2 virus encoded for an IR6 protein that was capable of forming the rod-like structures typical of cells infected with the wild-type virulent virus strain RacL11. (ii) Whereas the avirulent EHV-1 strains RacH and RacM36 are temperature-sensitive (in that virus replication at 40 degrees versus that at 37 degrees was reduced by as much as 7,500-fold), the HIR6-1 and HIR6-2 viruses, like RacL11 virus, were capable of significant replication at the elevated temperature. (iii) Electron microscopic analyses revealed that cells infected with the HIR6-1 or HIR6-2 virus, like those infected with virulent RacL11 virus, produced and released comparable numbers of virus particles at both 37 and 40 degrees. In cells infected with the RacH virus at 40 degrees, however, release of extracellular particles was inhibited by greater than 90% and relatively few of the particles were enveloped. (iv) Infections of BALB/cA mice revealed that both the HIR6-1 and HIR6-2 viruses, unlike the parent RacH virus, were as virulent as the wild-type RacL11 strain as judged by the criteria of body weight loss, development of clinical signs of EHV-1 infection, virus titers in the lung, and ability to cause viremia. These findings and those of our recent studies indicate that the IR6 protein is a major determinant of EHV-1 virulence and that the IR6 protein may play a role in virus maturation and/or egress.

Animals↗