Detection of PCR-amplified fungal DNA by using a PCR-ELISA system

In order to speed up and standardize polymerase chain reaction (PCR)-based detection of medically important fungi in clinical samples we established a combination of commercially available kits for DNA extraction, PCR amplification and detection of the amplicons. The PCR plate assay proved to be as sensitive and specific as our previously published assay (5 cfu ml(-1) blood). Moreover, in a selected group of patients, all patients with proven and probable invasive fungal infection were found to be PCR-positive. Thus the PCR plate assay was found to be a sensitive, technically simplified and standardized method with potential for adaptation to automation.

Nail patella syndrome in a cytogenetically balanced t(9;17)(q34.1;q25) carrier

Nail patella syndrome (NPS) is an autosomal dominant disorder characterized by dysplasia of the nails and patella, decreased mobility of the elbow, iliac horns and in some cases nephropathy. Linkage studies have localized the NPS locus to chromosome 9q34 within a 1-2 cM interval between D9S60 and the adenylate kinase gene (AK1), but the gene has remained elusive. We have identified a balanced t(9;17)(q34.1;q25) associated with NPS. By using FISH with probes from 9q the breakpoint region was narrowed to a 17.0 cM interval between D9S262 and ABL, which includes the NPS critical region. The patient showed the typical clinical features of NPS such as hypoplastic, deep-set nails, a dislocated elbow, iliac horns, and a polygonal patella. This suggests that the translocation has resulted from a break within or near the NPS gene, causing defective expression. The translocation in our patient may aid in the identification of the NPS gene.

Comparison of different methods for extraction of DNA of fungal pathogens from cultures and blood

Five commercially available extraction kits and an in-house DNA extraction method for the release of DNA from Candida albicans and Aspergillus niger cells were assessed for sensitivity, purity, duration, and cost. All commercially available kits helped to shorten the duration of DNA extraction. However, the sensitivity varied from 1 to 1,000 fungal cells/ml and costs varied from $0.10 to 2.30. The QIAmp Tissue kit was the commercially available assay that yielded the same sensitivity and purity of fungal DNA release as the in-house protocol but was the most expensive method. In comparing these two extraction protocols, a 99% concordance of PCR results for 125 blood samples analyzed could be demonstrated.

Molecular analysis of cyp51 from fluconazole-resistant Candida albicans strains

The target enzyme for fluconazole is sterol 14 alpha-demethylase, a cytochrome P450 encoded by cyp51. One mechanism of fluconazole resistance likely to occur in Candida albicans is through an altered target site. To test this hypothesis DNA sequencing of the cyp51 coding sequence from 19 fluconazole-resistant and 19 fluconazole-sensitive C. albicans was undertaken. A number of point mutations were identified in the resistant isolates which were not present in the sensitive ones: F105L (five), E266D (five), K287R (one), G448G (one), G450E (one), G464S (three) and V488I (one). These alterations are discussed in the light of a molecular model of the enzyme regarding potential roles in resistance. It was also demonstrated that sequence-specific primers can be employed to identify polymorphisms which may be associated with resistance; diagnostic tests for resistant strains will prove of value in combating this serious clinical problem.

Detection and identification of fungal pathogens in blood by using molecular probes

A PCR assay was developed for the detection and identification of Candida and Aspergillus species. The design of the oligonucleotide primer pair as well as the species-specific probes used for species identification was derived from a comparison of the sequences of the 18S rRNA genes of various fungal pathogens. The primers targeted a consensus sequence for a variety of fungal pathogens. The assay was tested for sensitivity and specificity with 134 fungal and 85 nonfungal isolates. To assess clinical applicability, 601 blood samples from four defined groups were tested: group A (n = 35), controls; groups B to D (n = 86), patients with febrile neutropenia, without fungal colonization (group B; n = 29) and with fungal colonization (group C; n = 36); and patients with documented invasive fungal infection (IFI) (group D; n = 21). The assay detected and, by species-specific hybridization, identified most of the clinically relevant Candida and Aspergillus species at 1 CFU/ml of blood. Amplification was 100% sensitive for all molds and yeasts tested, with Histoplasma capsulatum being the only non-Aspergillus species hybridizing with the Aspergillus spp. probe. None of 35 group A patients and only 3 of 65 group B and C patients were PCR positive. The sensitivity of the assay for specimens from patients with IFI (21 patients in group D) was 100% if two specimens were tested. For specificity, 3 of 189 specimens from patients at risk but with negative cultures were positive by the assay, for a specificity of 98%. PCR preceded radiological signs by a median of 4 days (range, 4 to 7 days) for 12 of 17 patients with hepatosplenic candidiasis or pulmonary aspergillosis. For the 10 patients with IFI responding to antifungal therapy, PCR assays became persistently negative after 14 days of treatment, in contrast to the case for 11 patients, who remained PCR positive while not responding to antifungal therapy. Thus, the described PCR assay allows for the highly sensitive and specific detection and identification of fungal pathogens in vitro and in vivo. Preliminary data from the screening of a selected group of patients revealed some value in the early diagnosis and monitoring of antifungal therapy.

Cytomegalovirus monitoring by polymerase chain reaction of whole blood samples from patients undergoing autologous bone marrow or peripheral blood progenitor cell transplantation

Sensitive screening for cytomegalovirus (CMV) by polymerase chain reaction (PCR) following autologous bone marrow or peripheral blood progenitor cell transplantation has not been evaluated. In a three-center study, 98 autograft transplant recipients were prospectively screened for CMV infection by PCR and culture techniques. At a median of 20 days (range, 3-28) after transplantation, 21 (39.6%) of 53 CMV-seronegative patients were PCR positive for CMV, and at a median of 17 days (range, 7-84) after transplantation, 19 (42.2%) of 45 CMV-seropositive patients were PCR positive for CMV. Low-level DNAemia (1-10 fg CMV DNA/mL blood) occurred for 1 week in 31 patients but was never associated with CMV disease. Of 9 patients who presented with at least two consecutive positive PCR results, 1 developed CMV pneumonia. No patients died because of CMV disease. Screening for CMV infection by PCR had a negative predictive value of 100% (as also observed after allogeneic transplantation), but its positive predictive value was significantly lower.

Detection of a de novo duplication of 1q32-qter by fluorescence in situ hybridisation in a boy with multiple malformations: further delineation of the trisomy 1q syndrome

We report a dysmorphic boy with a de novo partial trisomy 1q. The boy has microcephaly, bilateral cleft lip and palate, low set and dysmorphic ears, brain anomalies, pulmonary stenosis, duodenal obstruction, dysplastic kidneys, and bifid thumbs. The trisomic segment 1q32-qter is duplicated with an inverted insertion at 1p36.3. The aberration was initially detected at amniocentesis and confirmed and defined by GTG banding, chromosome microdissection, and FISH on postnatal blood samples. The parents had normal karyotypes. De novo partial duplications of chromosome 1q have rarely been reported. Comparison of our patient with other published pure trisomy 1q cases showed similarities which allowed the further delineation of the trisomy 1q syndrome.

Enhancement of migration by protein kinase Calpha and inhibition of proliferation and cell cycle progression by protein kinase Cdelta in capillary endothelial cells

Activation of protein kinase C (PKC) induces angiogenesis, migration, and proliferation of endothelial cells (EC), but can also prevent growth factor-induced EC proliferation. To determine whether these disparate effects are mediated by substrates of individual PKC isoenzymes, PKCalpha and PKCdelta were overexpressed in rat microvascular EC. Basal and stimulated migration were enhanced in PKCalpha EC compared with either PKCdelta or control EC. Serum-induced growth of PKCdelta EC was decreased, while that of PKCalpha cells was similar to control EC. Phorbol ester markedly inhibited PKCdelta EC growth but enhanced growth of PKCalpha and control EC. To determine possible causes for this altered proliferation, the effect of PKCdelta on adhesion, mitogen-activated protein kinase activity, and cell cycle progression was measured. Adherence of PKCdelta EC to vitronectin was significantly enhanced. Serum-induced extracellular signal-regulated kinase-2 activity was increased equally in both PKCalpha and PKCdelta EC above that of control, while extracellular signal-regulated kinase-1 activity was similar in all EC. Cell cycle analysis suggested that PKCdelta EC entered S phase inappropriately and were delayed in passage through S phase. Thus, PKCalpha may mediate some proangiogenic effects of PKC activation; conversely, PKCdelta may direct antiangiogenic aspects of overall PKC activation, including slowing of the cell cycle progression.

Monitoring of CMV infection: a comparison of PCR from whole blood, plasma-PCR, pp65-antigenemia and virus culture in patients after bone marrow transplantation

Rapid, specific and sensitive methods are essential for early detection of CMV infection in patients after marrow transplantation. Thus, in a prospective study, PCR from whole blood, plasma-PCR, pp65-antigenemia and virus culture were used and compared in 20 consecutive marrow transplant recipients for early diagnosis of CMV infection and monitoring of antiviral therapy. Moreover, semi-quantification of the viral load in blood samples by PCR from whole blood or plasma and pp65-antigenemia was performed. Fifteen out of 20 patients were found to be CMV positive by PCR from whole blood, plasma-PCR and pp65-antigenemia, whereas only 9/20 developed culture-proven viremia and/or viruria. PCR from whole blood, plasma-PCR and pp65-antigenemia revealed identical results in 96 and discordant results in 13 of 109 blood samples (P < 0.01). The efficacy of antiviral therapy was monitored by semi-quantitative scoring of pp65-antigen-positive leukocytes and/or CMV-DNA levels in blood and plasma samples. Twelve of 13 patients were found to be CMV negative by all methods after 14 days of ganciclovir therapy. A good correlation of the semi-quantitative evaluation of the three assays was demonstrated. Thus, all three highly sensitive assays seem to be suitable for screening patients at risk for CMV infection and monitoring the efficacy of antiviral therapy.

Polymerase chain reaction monitoring reduces the incidence of cytomegalovirus disease and the duration and side effects of antiviral therapy after bone marrow transplantation

Culture-based preemptive therapy with ganciclovir was shown to reduce the incidence of cytomegalovirus (CMV) disease after bone marrow transplantation (BMT). Culture techniques did not detect CMV in 12% to 13% of patients before the onset of CMV disease. In a prospective study, 71 patients either received preemptive therapy based on polymerase chain reaction (PCR) technique (37 patients) or on culture assays (34 patients). In both groups, therapy was continued until clinical signs disappeared and PCR negativity was documented. Twenty-two patients in the PCR group and 15 patients in the culture group received antiviral therapy. PCR allowed detection of the virus (median day, +32 v day +49; P = .006) and introduction of antiviral therapy (median day, +44 v day +54; P = .02) earlier than did culture assays. The incidences of CMV disease (2 of 37 v 8 of 34 in PCR group v culture group, respectively; P = .02) and CMV-associated mortality (0 of 37 v 5 of 34 in PCR group v culture group, respectively; P = .02) were decreased, and the duration of ganciclovir therapy (P < .001) was shorter in the PCR-monitored group. Incidence and median duration of severe neutropenia (less than 500/microL) were lower in the PCR group (two v eight episodes, P = .02; median duration, 1.5 v 5 days, P = .04), as was the incidence of nonviral infections during/after antiviral therapy (2 of 37 v 9 of 34; P = .012). Thus, preemptive therapy based on more sensitive detection methods such as the PCR assay reduces the incidence of CMV disease and CMV-related mortality. Additionally, stopping and withholding antiviral therapy in a PCR-negative patient is safe and allows reduction of the duration and side effects of antiviral therapy.

Increased monoamine oxidase B activity in plaque-associated astrocytes of Alzheimer brains revealed by quantitative enzyme radioautography

The aetiology and pathogenesis of Alzheimer's disease are currently poorly understood, but symptomatic disease is associated with amyloid plaques, neurofibrillary tangles, neuronal loss and numerous alterations of neurotransmitter systems in the CNS. Monoamine oxidase type B is known to be increased in Alzheimer diseased brains. The distribution and abundance of catalytic sites for monoamine oxidases A and B in post mortem human brains of 11 Alzheimer disease cases and five age-matched controls were investigated by quantitative enzyme radioautography. Using tritiated monoamine oxidase inhibitors (Ro41-1049 and lazabemide)--as high affinity substrates selective for monoamine oxidases A and B, respectively--it was found that monoamine oxidase B activity increased up to three-fold exclusively in temporal, parietal and frontal cortices of Alzheimer disease cases compared with controls. This increase was restricted to discrete patches (approximately 185 microns in diameter) which occupied approximately 12% of the cortical areas examined. In other brain regions (hippocampal formation >> caudate-putamen > cerebellum), patches of [3H]lazabemide-enriched binding were less abundant. [3H]Ro41-1049 binding (i.e. monoamine oxidase A) was unchanged in all tissues of diseased versus control brains. The monoamine oxidase B-enriched patches in all cortical regions correlated, in their distribution and frequency, with glial fibrillary acidic protein-immunoreactive clusters of astrocytes. Diffuse and mature beta-amyloid-immunoreactive senile plaques as well as patches of high density binding of [3H]PK-11195--a high-affinity ligand for peripheral-type (mitochondrial) benzodiazepine binding sites in microglia/macrophages--were found throughout Alzheimer diseased cortices. The up-regulation of monoamine oxidase B in plaque-associated astrocytes in Alzheimer's disease--in analogy to its proposed role in neurodegenerative disorders such as Parkinson's disease--might, indirectly, be a potential source of cytotoxic free radicals. Lazabemide, a selective reversible monoamine oxidase B inhibitor, is currently under clinical evaluation for the treatment of Parkinson's and Alzheimer's diseases. We conclude that enzyme radioautography with [3H]lazabemide is a reliable high resolution assay for plaque-associated astroglioses in Alzheimer's disease. Its clinical diagnostic utility for positron emission tomography or single photon emission computer tomography studies is being investigated.

Purification and characterization of a novel metalloprotease from human brain with the ability to cleave substrates derived from the N-terminus of beta-amyloid protein

The main component of amyloid plaques in Alzheimer's disease (AD) is the beta-amyloid peptide (beta/A4), derived from beta-amyloid precursor proteins (beta-APPs). In order to identify proteases possibly involved in the cleavage at the N-terminal site of beta/A4 a chromogenic peptide corresponding to this region of beta-APP was used. Here the purification and characterization of a new human brain protease with the ability to cleave the beta-APP peptide as well as beta-APP in vitro are described. The enzyme has a molecular mass of 100 kDa and belongs likely to the class of metalloproteases. It should further be named "MP100". The enzyme has a very broad substrate specificity in vitro.

Accumulation of a 50 kDa N-terminal fragment of beta-APP695 in Alzheimer's disease hippocampus and neocortex

Proteolytic processing of beta-amyloid precursor protein (beta-APP) is a key event in the formation of beta-amyloid deposits in Alzheimer's disease (AD) brains and is likely to be accompanied by the accumulation of cleavage products other than the beta/A4 protein. Using a beta-APP695-specific monoclonal antibody in quantitative immunoblotting, a 50 kDa N-terminal fragment of beta-APP695 was detected in neocortex, hippocampus and cerebellum of AD patients and control individuals. The mean level of this fragment was higher in AD hippocampus and neocortex as compared to controls, suggesting that beta-APP695 fragments are generated in various brain regions but that the proteolytic processing is increased in pathologically affected brain areas.

Modulation of beta-amyloid precursor protein secretion in differentiated and nondifferentiated cells

The regulation of beta-amyloid precursor protein (beta-APP) secretion was compared in differentiated and nondifferentiated PC12 and B104 cells. Phorbol esters stimulated the release of beta-APP in all cells examined. However, differentiated PC12 cells were much more sensitive to phorbol ester treatment than nondifferentiated PC12 cells and their beta-APP release was also induced by the protein phosphatase inhibitor okadaic acid and the Ca(++)-ionophore A23187. In contrast, beta-APP release from B104 cells was strongly stimulated by A23187 and to lesser degree by phorbol esters. This effect was most pronounced in nondifferentiated B104 cells, which might be due to a higher basic release of beta-APP from differentiated B104 cells. Thus, the regulation of beta-APP cleavage and release varies depending on the cell type and differentiation state of the cell.

Involvement of amyloid precursor protein in memory formation in the rat: an indirect antibody approach

The potential role of different isoforms of amyloid precursor proteins (APPs) in memory and learning processes was investigated in rats using antibodies differentiating between APP isoforms containing or lacking the Kunitz protease inhibitor (KPI) domain. Rats received intracerebroventricular injection of control immunoglobulins (IgGs), anti-KPI-APP (= anti-P3) or anti-N-terminus-APP (= anti-P4). No immediate effects on learning of a passive avoidance task were observed; however, performance evaluated 1 day later was somewhat impaired by the anti-P3 antibody (reacting with APPKPI) and even more markedly impaired by the anti-P4 antibody (reacting with both APP695 and APPKPI) relative to control antibody. The antibodies did not affect performance of an active avoidance task acquired prior to the experimental treatment or active avoidance learning 8 days post-treatment. These results suggest that blockade of APP by an antibody injected intracerebroventricularly impairs the consolidation and/or retrieval of memory in rats.

Beta-amyloid precursor protein isoforms in various rat brain regions and during brain development

To address the question of the possible functions of different Alzheimer's disease beta-amyloid precursor protein (beta-APP) isoforms in the brain, we studied their expression at different times during postnatal rat brain development and in various regions of the adult rat brain. Polyclonal antibodies directed to two peptide antigens were used. The majority of all beta-APP forms was found to be soluble as revealed by western blot analysis. The highest level of most beta-APP forms was reached in the second postnatal week, which is the time of brain maturation and completion of synaptic connections. Strikingly high concentrations of the Kunitz protease inhibitor-containing beta-APP were present in the adult olfactory bulb, where continuous synaptogenesis occurs in the adult animal. These findings support the idea of an involvement of beta-APPs in the processes of cell differentiation and, probably, in the establishment of synaptic contacts.