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Biomedical subjects

U Reischl

Publications and source records attributed to U Reischl.

At least 55 records · Page 3Linked to original sources
PubMed1998

Clinical evaluation of the automated COBAS AMPLICOR MTB assay for testing respiratory and nonrespiratory specimens.

We evaluated the COBAS AMPLICOR PCR system (Roche Diagnostics) for the routine detection of Mycobacterium tuberculosis complex (MTBC) in clinical specimens. Diagnostic culture, considered as the reference method, was performed with BACTEC, Löwenstein-Jensen, Stonebrink, and Kirchner media. Occasionally MB-Redox, ESP, or MGIT medium was also used. A total of 643 respiratory and 506 nonrespiratory specimens collected from 807 patients were investigated. Of the 95 culture-positive specimens, 80 were COBAS AMPLICOR MTB positive, and of the 1,054 culture-negative specimens, 1,044 were COBAS AMPLICOR MTB negative. After resolving discrepancies by review of the medical history, the overall sensitivity, specificity, and positive and negative predictive values for the COBAS AMPLICOR MTB assay, respectively, were 83.5, 98.8, 86.7, and 98.6% compared to those of diagnostic culture. In smear-positive specimens, the sensitivity of the COBAS AMPLICOR MTB assay was 96%, versus 48% for smear-negative specimens. No significant differences in the test performance between respiratory and nonrespiratory specimens were observed. The overall inhibition rate was less than 2%, excluding stool specimens. The clear advantages of the COBAS AMPLICOR PCR system are standardized procedures and reagents for specimen processing as well as an internal control for reliable monitoring of PCR inhibitors. By simplifying the work flow through a completely automated amplification and amplicon detection procedure, the COBAS AMPLICOR PCR system proved itself as a very useful component for routine diagnostic procedures.

Automation↗
PubMed1998

16S rRNA sequence diversity in Mycobacterium celatum strains caused by presence of two different copies of 16S rRNA gene.

Direct sequencing of the 16S rRNA gene (16S rDNA) of Mycobacterium celatum isolates showed ambiguities, suggesting heterogeneity. Cloned 16S rDNA yielded two copies of the gene, which differed by insertion of a thymine at position 214 and by additional mismatches. Restriction fragment length polymorphism analysis confirmed the presence of two copies of 16S rDNA within the bacterial chromosome.

Base Sequence↗
PubMed1997

[Rapid diagnosis of infectious endophthalmitis using polymerase chain reaction (PCR): a supplement to conventional microbiological diagnostic methods].

BACKGROUND: Endophthalmitis is, although relatively rare, a serious intraocular infection, which could result in a loss of visual function. Therefore, the rapid diagnosis and initiation of the appropriate treatment is of critical importance. To date, approximately 60 percent of eyes with a clinical diagnosis of infectious endophthalmitis show a positive microscopic or culture result. By using the very sensitive polymerase chain reaction this number might increase. PATIENTS AND METHODS: In a series of 12 eyes with infectious endophthalmitis we have performed microscopic investigations, diagnostic culture and polymerase chain reaction in aqueous humor and vitreous in order to detect the infectious agent. RESULT: Microscopic investigations showed a positive result in the vitreous of 3 eyes. This number improved to 6 eyes using culture media. Significant less positive results were obtained in the aqueous humor. The infectious agent could be detected in the aqueous humor in all 12 eyes and in the vitreous in 9 eyes by PCR. Only in 2 eyes with a delayed endophthalmitis the vitreous was negative. CONCLUSIONS: The detection of the infectious agents was more successful using PCR compared to conventional microbiological tests. In particular, for the diagnosis of delayed endophthalmitis PCR proves to be very superior. In all cases of delayed endophthalmitis the pathogen could be detected in the aqueous humor.

Aqueous Humor↗
PubMed1997

[Polymerase chain reaction (PCR) and its possible applications in diagnosis of infection in ophthalmology].

The polymerase chain reaction (PCR) is a relatively new molecular biology-based technique that allows the specific identification of small amounts of DNA or RNA. This technique offers significant advantages compared to conventional microbiological tests, such as microscopy or culture. Increasing numbers of immunosuppressed patients with intraocular infections and, improvements in antibiotic therapy for specific organisms require a more accurate diagnosis. PCR is capable of providing such requirements. This technique is evolving rapidly and in cooperation with clinicians and molecular biologists a number of applications are being developed, which contribute to the growing demands on microbiological testings. This article describes the basics, indications and the limitations of the polymerase chain reaction.

Diagnosis, Differential↗
PubMed1997

Mycobacterium hassiacum sp. nov., a new rapidly growing thermophilic mycobacterium.

A new rapidly growing, scotochromogenic mycobacterium was isolated from urine. This strain is thermophilic (it grows at 65 degrees C), tolerates 5% NaCl, and was unable to utilize any of the sugars tested or citrate or to take up iron. The isolate splits benzamide, urea, nicotinamide, and pyrazinamide and is sensitive to streptomycin, ethambutol, cycloserine, ciprofloxacin, and chlarithromycin but resistant to isoniazid, rifampin, and prothionamide. These characteristics clearly place this organism in a new mycobacterial species, which was confirmed by the unique 16S rRNA nucleotide sequence. The high level of similarity between this rapid grower and Mycobacterium xenopi is surprising. For this new rapidly growing scotochromogenic and thermophilic mycobacterium we propose the name Mycobacterium hassiacum sp. nov.

Bacteriological Techniques↗
PubMed1997

Visual Health Information Profile (VHIP). A quantitative approach for analysing the health status of a population.

A new approach for illustrating and analysing the health status of a given population is presented. The concept takes the multi-dimensional nature of health into account. It is based on a clearly out-lined indicator hierarchy, a decile reference system and a computerised information system. The instrument displays the health status of a population and allows comparisons to be made of various health aspects for a given population at different times and allows comparisons to be made of different populations during given time periods. It is possible to represent quantitative and qualitative aspects of health, to monitor the impact of interventions, and to assess the extent to which objectives in the health field have been achieved. Therefore, it can serve as an instrument for communication between policy makers and scientists to manage and to co-ordinate programs that aim at an improvement of the health status and to assist in the priority setting process. The method was applied to several countries using the World Health Organisation's (WHO) "Health For All Global Indicator Database" as the main data source. Country and region specific health status patterns could be generated showing the practicability of the approach. Using a computerised information system, a high degree of transparency and flexibility with respect to the input data and the choices of measurables was achieved.

Computer Graphics↗
PubMed1996

Application of molecular biology-based methods to the diagnosis of infectious diseases.

The basis for effective treatment and cure of a patient is the rapid diagnosis of the disease and its causative agent, which is founded on the analysis of the clinical symptoms coupled with laboratory tests. As we approach the 21st century, clinicians are becoming increasingly able to diagnose and treat diseases at the molecular level. The rapid development of new methods and techniques in the area of molecular biology has gained new insights into the genetic and structural features of a considerable number of human pathogens. These results obtained by intensive basic research are currently leading to improved diagnostic procedures. Basically, there are four different possibilities for laboratory diagnosis of infections: 1. direct detection of the pathogens (e.g., microscopy and/or culture), 2. detection of protein components of the pathogens with the help of specific antibodies (e.g., antigen capture ELISA) 3. IgA-, IgM- and IgG-specific detection of antibodies directed against a given pathogen and changes in their corresponding titer, and as the most sensitive method, 4. specific detection of nucleic acids (e.g., PCR) of the pathogens. Here, the human immunodeficiency virus (HIV) and Mycobacterium tuberculosis are serving as examples to review the recent developments as well as the future perspectives in molecular biology-based laboratory diagnosis.

Bacterial Infections↗
PubMed1996

[Molecular biology methods in detection of mycobacteria. Improved and newly developed test systems for the diagnosis of mycobacteria].

In the coming years, the accurate and rapid microbiological detection of mycobacteria will gain in importance, since infections with Mycobacterium tuberculosis and ubiquitous mycobacteria are expected to increase, in particular in immunocompromised persons. In addition to the classical biochemical methods of detection involving the use of the microscope and cultures, molecular biological techniques are already being used today. The present overview therefore discusses the principles of the major methods. These include the use of the major DNA probes, DNA amplification techniques (PCR) with subsequent DNA sequencing for species determination, and RFLP analysis, which is employed to deal with epidemiological problems. Also described is the Bactec method for culturing in a liquid medium which forms the basis of various modern examination techniques.

AIDS-Related Opportunistic Infections↗
PubMed1996

Specific and sensitive two-step polymerase chain reaction assay for the detection of Salmonella species.

A polymerase chain reaction (PCR) assay was applied for the selective amplification of a characteristic sequence within a Salmonella-specific chromosomal fragment. A two-temperature PCR cycle enhanced both the speed and overall sensitivity of the amplification procedure. Twenty-one well-characterized Salmonella strains and a number of non-Salmonella strains were tested. With the exception of the rarely isolated Salmonella arizonae strain, the PCR-based approach enabled the specific identification of Salmonella with a detection limit of 10(3) organisms. In combination with a nested PCR assay, as few as ten organisms were detectable. Specificity was demonstrated as no distinct amplification products were detectable with any of the tested non-Salmonella strains. With a pre-enrichment step using paramagnetic anti-Salmonella beads, an increase in sensitivity was observed in the case of clinical samples while the amplification process was not influenced.

DNA, Bacterial↗
PubMed1996

Expression and purification of an Epstein-Barr virus encoded 23-kDa protein and characterization of its immunological properties.

Serodiagnosis of Epstein-Barr virus (EBV) infection is currently based on the detection of antibodies to distinct EBV antigens by immunofluorescence and enzyme-linked immunosorbent assay-based tests, or in part on the detection of heterophile antibodies by the Paul-Bunnell-Davidson heterophile assay. In the past few years, the specificity and the sensitivity of serodiagnostic assay systems has been improved considerably by the use of purified recombinant EBV antigens. Screening of EBV-positive sera for antigenic reactivities by immunoprecipitation with extracts of EBV-positive cells revealed a 23-kDa protein (p23) that was recognized by antibodies from all EBV carriers tested. Open reading frame BLRF2 was identified as the coding region for this protein. After cloning and high-level expression of the BLRF2 open reading frame as DHFR fusion protein in Escherichia coli, the recombinant protein was purified to near homogeneity with the help of continuous elution electrophoresis. Sera from both EBV-positive and -negative donors were screened by immunoblot analysis and enzyme-linked immunosorbent assay for IgM and IgG antibodies against the EBV-encoded protein p23. Since anti-p23 antibodies were not detectable in 30 of 30 EBV-negative sera, and 294 of 302 EBV-positive sera had either IgM and/or IgG antibody responses to this protein, recombinant p23 seems to be a useful diagnostic marker for EBV-infection.

Antibodies, Viral↗
PubMed1996

Importance of simultaneous active cytomegalovirus and Epstein-Barr virus infection in renal transplantation.

BACKGROUND: Although being the most common infective complication after transplantation, cytomegalovirus (CMV) infection does not always produce disease symptoms in immunosuppressed patients. Development of CMV disease may depend on different factors such as virulence of particular CMV strains and impairment of CMV-specific immune reactions. OBJECTIVE: Demonstration of the importance of simultaneous Epstein-Barr virus (EBV) activation for development of symptomatic CMV infections. STUDY DESIGN: 208 renal transplantation patients were monitored for 3 years with respect to (i) CMV and EBV replications, and (ii) clinical symptoms associated with combined and single infections, respectively. RESULTS: CMV and EBV replications were observed in 22% and 19% of the patients, respectively. Many of these active virus infections were found to overlap in time (59% and 74% of all active CMV and EBV infections, respectively). The increased detection of combined CMV and EBV infections probably does not result from higher initial immunosuppression in these patients, since the percentage of patients receiving OKT3 or ATG was almost identical in the groups of single and combined infections. In 18 cases of combined infections, CMV replication preceeded EBV replication, while EBV replication prior to CMV replication was observed in one case only, indicating that activation of latent EBV infection may be induced during active CMV infection. CONCLUSIONS: Simultaneous replication of both viruses seems to be clinically important, since severe clinical symptoms were observed only in the group of combined CMV and EBV infections. Symptoms were similar to the clinical pictures of CMV disease. Thus, simultaneous EBV replication may be an important co-factor for the development of CMV disease, possibly by further decreasing the number of functional CD4 T cells or enhancing the CD8-positive cytolytic/suppressor T-cell subset as reflected by the comparatively stronger decrease of CD4/CD8 ratio during simultaneous CMV and EBV replication, particularly in the case of symptomatic infections.

Journal Article↗
PubMed1996

Pathogenesis of chronic Epstein-Barr virus infection: detection of a virus strain with a high rate of lytic replication.

In rare cases Epstein-Barr virus (EBV) leads to chronic active infection (CAEBV) which is characterized by persistant symptoms of infectious mononucleosis. Previously we described a case of persisting polyclonal B-cell lymphocytosis (PPBL) that was associated with CAEBV. Using reverse transcription and polymerase chain reaction we showed that in late passages of a spontaneous cell line, SM, latent EB viral genes such as EBNA1, EBNA2, EBNA3A/3B/ 3C, LMP1 and LMP2A were active. The master gene of the lytic cycle, BZLF1, was silent. This indicated that there was no general defect in immortalization and establishing latency by this CAEBV isolate SM. We obtained virus from the standard immortalizing strain B95-8 and the CAEBV strain SM from latently infected LCL quantified the number of virus particles by competitive PCR and demonstrated that the impaired capacity to immortalize umbilical cord blood lymphocytes was a virus strain-specific property, and was not due to an incapability to infect purified CD19+ B lymphocytes. Transcription of latency- and immortalization-associated genes such as EBNA1, EBNA2 and LMP2A was reduced, in contrast to a strongly enhanced activity of the master gene of the lytic cycle, BZLF1. A scenario for an antagonistic regulation of lytic and latent cycle genes is presented and a role for the pathogenesis of CAEBV is discussed.

B-Lymphocytes↗
PubMed1996

Lymphoproliferative responses after infection with human parvovirus B19.

Immunity after infection with the parvovirus B19 is assumed to be conferred by a humoral immune response with development of neutralizing antibody. In contrast, little is known about the nature of T-cell-mediated responses to parvovirus B19 infection in humans. We used recombinant proteins VP1, VP2, and NS1, as well as a recombinant VP1-specific amino-terminal sequence, to test the proliferative responses of peripheral blood mononuclear cells after infection of otherwise healthy individuals with parvovirus B19. These proteins were used as antigens for the stimulation of freshly isolated cells. The results show that a B19 virus-specific cellular immunity develops that is directed against the capsid proteins VP1 and VP2. We also demonstrate that viral determinants are presented to CD4+ T cells by HLA class II molecules.

Antigens, Viral↗
PubMed1996

The importance of the corneal epithelium in excimer-laser photorefractive keratectomy.

To evaluate the importance of the epithelium for postoperative regression we undertook excimer-laser photoreactive keratectomy (PRK) in six rabbits. After the epithelium had been removed mechanically, two rabbits underwent a -3.0 D procedure; two rabbits, a -6.0 D procedure; and two rabbits, a -9.0 D procedure. Refraction was monitored pre- and postoperatively using streak retinoscopy. Rabbits were killed at 3 weeks after PRK and the thickness of the corneal epithelium in the centre of the ablation zone and in an untreated area just outside the treatment zone was measured using light microscopy. At the time of killing, no stromal haze was visible on slit-lamp biomicroscopy. In all rabbits the thickness of the corneal epithelium over the untreated area was between 31.4 and 36.7 microns. In contrast, the thickness of the epithelium in the centre of the ablation zone in rabbits treated with a -3.0 D procedure was only slightly increased, and retinoscopy showed a change in refraction of around 3 D. All other rabbits showed a significant increase in epithelial thickness, whereas the amount of thickness correlated with the amount of myopic regression. One rabbit in the -6.0 D group showed an increase in epithelial thickness of 18.4 microns and a myopic regression of 1.5 D. In both rabbits in the -9.0 D group the amount of corneal tissue removed by the laser was nearly completely substituted by epithelial hyperplasia. Postoperative retinoscopy showed nearly the same refraction as had been obtained preoperatively. In summary, the postoperative control of epithelial thickness seems to be an important factor for the success of excimer-laser PRK and, in particular, for high degrees of myopia.

Animals↗
PubMed1995

[Laboratory diagnosis of HIV infection].

Recent use of modern methods in the field of molecular biology has provided new insights into the genetic and structural nature of HIV, which are now increasingly being applied to the diagnostic work-up. For the reliable laboratory diagnosis of HIV infection, three different possibilities are available: detection of specific antibodies against viral proteins (anti HIV AB), detection of the virus itself (HIV antigen) and detection of viral nucleic acid using in vitro amplification techniques. In this overview, we compare clinical and diagnostic parameters of an HIV infection, and discuss the current state of the art of an HIV infection and the future prospects offered by new molecular biological methods such as the use of recombinant antigens or the polymerase chain reaction (PCR) for the detection of viral nucleic acid.

AIDS Serodiagnosis↗