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Biomedical subjects

P C Wever

Publications and source records attributed to P C Wever.

At least 19 recordsLinked to original sources
PubMed2006

[Two patients with mumps].

Two patients, men aged 17 and 19 years respectively, were admitted with parotitis epidemica and orchitis caused by mumps. The second patient also had meningitis. PCR analysis revealed that, in both cases, the causative agentwas a mumps virus that was genetically related to a wild-type virus responsible for an outbreak in Singapore. This viral strain was also responsible for a mumps outbreak at Hotel School The Hague in September 2004. Both patients were not fully vaccinated. Both patients were from regions in which clustering of patients with clinical signs of mumps has been seen. Interestingly, a number of patients with confirmed mumps had been fully vaccinated. Possible explanations for the increase in mumps cases include low vaccination and immunity levels, primary and secondary vaccine failure and the emergence of genetically disparate mumps viruses.

Adolescent↗
PubMed2006

Widely distributed and predominant CTX-M extended-spectrum beta-lactamases in Amsterdam, The Netherlands.

Three hundred sixty Enterobacteriaceae and nonfermenting gram-negative bacilli, isolated during one week in May 2004 at five hospitals in Amsterdam, The Netherlands, were evaluated for the presence of extended-spectrum beta-lactamases (ESBLs). A prevalence of 7.8% was found, in contrast to the 1% observed in 1997. CTX-M ESBLs dominated, and four types were identified in 18 isolates.

Anti-Bacterial Agents↗
PubMed2001

Successful treatment with recombinant factor VIIa of therapy-resistant severe bleeding in a patient with acquired von Willebrand disease.

We describe an elderly man who presented with life-threatening hematuria and gastrointestinal bleeding caused by acquired von Willebrand disease associated with monoclonal gammopathy of undetermined significance (MGUS). Standard therapy with desmopressin, von Willebrand factor-containing factor VIII concentrate, tranexamic acid, and immunoglobulin failed to achieve adequate hemostasis. However, treatment with recombinant activated factor VII (rFVIIa) arrested the bleeding completely. Since acquired von Willebrand disease can lead to life-threatening hemorrhage, clinicians should consider rFVIIa as an effective treatment option if standard therapy fails.

Aged↗
PubMed2000

Rapid diagnosis of Legionnaires' disease using an immunochromatographic assay for Legionella pneumophila serogroup 1 antigen in urine during an outbreak in the Netherlands.

A new immunochromatographic assay for rapid qualitative detection of Legionella pneumophila serogroup 1 antigen in urine specimens was used during an outbreak of legionellosis in The Netherlands. The assay seems of the utmost value in providing a rapid diagnosis of Legionnaires' disease in patients with severe community-acquired pneumonia in an outbreak setting.

Antigens, Bacterial↗
PubMed1999

Interferon-gamma preferentially reduces memory/effector CD8 T lymphocytes in healthy subjects.

To evaluate the influence of interferon-gamma (IFN-gamma) on leukocyte dynamics, with a focus on naive and memory T cells, we studied 6 healthy subjects twice in a placebo-controlled trial: once after the administration of recombinant human IFN-gamma (rhIFN-gamma; 100 microg/m2 subcutaneously) and at least 4 weeks later, after the administration of saline solution. Additionally, we studied the expression of adhesion molecules on T lymphocytes after in vitro incubation of whole blood with rhIFN-gamma. IFN-gamma induced a significant depletion in the number of T lymphocytes (P < .05 vs control), which was more severe in the CD8+ cell subset than in the CD4+ T cell subset. The numbers of naive CD4+ T cells and memory CD4+ T cells were equally affected by IFN-gamma, whereas within the CD8+ T cell subset, memory/effector cells disappeared preferentially as compared with naive cells (P < .05 vs control). In addition, IFN-gamma induced a decrease in B cells, NK cells, and monocytes. After an initial increase, granulocyte counts decreased significantly as compared with controls. These effects appeared not to be caused by the minimal rise in plasma cortisol levels (P < .05 vs control). In vitro, IFN-gamma did not up-regulate the expression of CD11a, NKI L16, CD11b, LFA-3, or VLA-4. We conclude that the administration of a single dose of IFN-gamma to healthy subjects profoundly affects the numbers of several leukocyte subsets in the peripheral blood compartment.

Adult↗
PubMed1999

Expression of granzyme B during primary cytomegalovirus infection after renal transplantation.

CD8+ T cells employ granzyme B (GrB) to induce apoptosis in target cells. Increased expression of GrB has been put forward as a diagnostic marker in transplant rejection and viral infection. Three-color flow cytometric analysis revealed that peripheral blood CD8+ T lymphocytosis during primary cytomegalovirus infection after renal transplantation resulted from expansion of a CD8+GrB+CD62L+ T cell subset that was almost absent during stable transplant function or acute rejection. This expansion coincided with a temporary increase in systemic soluble GrB (sGrB) levels. No such increase was observed during stable transplant function or acute rejection. Thus, the primary immune response to cytomegalovirus infection is accompanied by appearance of CD8+GrB+CD62L+ T cells and increased sGrB levels in the peripheral blood compartment. Determination of the latter may provide a novel approach for monitoring viral infections.

Adolescent↗
PubMed1999

CD4dullCD8bright double-positive T-lymphocytes have a phenotype of granzyme Bpos CD8pos memory T-lymphocytes.

BACKGROUND: T-lymphocytes that co-express CD4 and CD8 antigens may be found in small percentages in the peripheral blood of healthy individuals, and have a CD4brightCD8dull phenotype. CD4dullCD8bright T-lymphocytes have been found only in temporal association with some viral infections. METHODS: Four-colour flow cytometric analysis of peripheral blood mononuclear cells from a renal transplant recipient with cytomegalovirus infection was performed. RESULTS: A small but clearly distinguishable subpopulation of CD4dullCD8bright double-positive T-lymphocytes was detected, that exhibited phenotypic characteristics of cytotoxic T-lymphocytes and were granzyme B positive. Furthermore, no naive cells appeared to be present within this subpopulation. CONCLUSIONS: CD4dullCD8bright double-positive T-lymphocytes are enriched for memory and effector cytotoxic T cells.

CD4 Antigens↗
PubMed1998

Mechanisms of lymphocyte-mediated cytotoxicity in acute renal allograft rejection.

BACKGROUND: Graft-infiltrating T-cell (GIC) lines cultured from biopsies obtained during acute renal allograft rejection exhibit donor-specific cytotoxicity toward proximal tubular epithelial cell (PTEC) lines cultured from corresponding biopsies. This system allows for study of the relative contributions of perforin/granzyme B (GrB)- and Fas ligand (FasL)-based cytotoxicity to killing of PTEC. METHODS: Expression of perforin, GrB and FasL was analyzed by immunocytochemical staining of cytocentrifuge preparations of GIC lines cultured from 10 renal allograft biopsies. Specific inhibitors of the perforin/GrB- and FasL-based pathways were used in 51Cr release and apoptosis assays to determine their relative contributions to cytotoxicity of GIC lines toward corresponding donor PTEC lines. RESULTS: Cells with a strong granular pattern were observed upon immunocytochemical staining of GIC lines with anti-perforin or anti-GrB monoclonal antibodies. A diffuse staining pattern was observed upon staining with anti-FasL polyclonal antibodies. Six of eight GIC lines cultured from biopsies with acute rejection showed cytotoxicity toward corresponding donor PTEC lines, whereas two GIC lines cultured from biopsies without rejection did not. Preincubation of cytotoxic GIC lines with concanamycin A, an inhibitor of the perforin/GrB-based pathway, caused inhibition of both lysis and apoptosis of PTEC. Inhibition was not observed upon incubation with monoclonal antibodies that inhibit Fas. CONCLUSIONS: The perforin/GrB-based pathway is mainly responsible for cytotoxicity of GIC lines toward corresponding donor PTEC lines, suggesting that this pathway predominates in tubular epithelial cell destruction by cytotoxic T lymphocytes during acute renal allograft rejection in vivo.

Acute Disease↗
PubMed1998

Human eosinophils express, relative to other circulating leukocytes, large amounts of secretory 14-kD phospholipase A2.

Human eosinophils perform several functions dependent on phospholipase A2 (PLA2) activity, most notably the synthesis of platelet-activating factor (PAF) and leukotriene C4 (LTC4). Several forms of PLA2 have been identified in mammalian cells. In the present study, the 14-kD, secretory form of PLA2 was detected in human eosinophils by immunocytochemical staining with the specific monoclonal antibody (MoAb) 4A1. In contrast, preparations of neutrophils, monocytes, lymphocytes, and basophils did not show detectable staining. With two MoAbs in a sandwich enzyme-linked immunosorbent assay (ELISA), large amounts of sPLA2 were detected in lysates of eosinophils, that were 20-fold to 100-fold higher than in the other circulating leukocytes (ie, neutrophils, basophils, monocytes, and lymphocytes). In addition, with a commercially available sPLA2 activity assay kit, we were able to show high activity of sPLA2 in human eosinophils relative to neutrophils. Investigations at the ultrastructural level showed that sPLA2 in eosinophils is mainly located in specific granules. Immunoelectron microscopy also visualized sPLA2 within phagosomes after addition of opsonized particles to the eosinophils. However, sPLA2 was not detected in the cell-free supernatants of activated eosinophils, in contrast to eosinophil-cationic protein (ECP), which colocalizes with sPLA2 in resting eosinophils. These findings warrant further studies into the role of sPLA2 in eosinophil function.

Basophils↗
PubMed1998

Extracellular granzymes A and B in humans: detection of native species during CTL responses in vitro and in vivo.

Activated CTLs and NK cells induce apoptosis via multiple mechanisms, including that termed granule exocytosis. The latter pathway consists of vectorial secretion of perforin and a family of granule-associated serine proteases (granzymes) to the target cell. To establish whether granzymes are released extracellularly during cytolytic reactions in vivo, ELISAs that measure the native enzymes were developed and were found to specifically detect granzyme A (GrA) and granzyme B (GrB) at picogram concentrations. Low levels of GrA and GrB were present in plasma of healthy individuals (GrA, 33.5 pg/ml (median); GrB, 11.5 pg/ml (median)), whereas significantly higher levels were present in patients with ongoing CTL response, i.e., patients suffering from infections by EBV or HIV type 1. Markedly elevated levels were also noted in synovial fluid of patients with active rheumatoid arthritis. The measurement of soluble granzymes should be useful to assess clinical disorders associated with activated CTL and NK cells. Furthermore, these results suggest that granzymes mediate biologic effects beyond their described role in apoptotic cell death.

Animals↗
PubMed1998

The CD8+ granzyme B+ T-cell subset in peripheral blood from healthy individuals contains activated and apoptosis-prone cells.

Granzyme B (GrB) has been implicated in induction of apoptosis in target cells. The presence of GrB in peripheral blood CD8+ T cells from healthy individuals was analysed in immunocytochemical and flow cytometric studies. Furthermore, CD8+ GrB- T cells and CD8+ GrB+ T cells were compared regarding phenotypical characteristics and susceptibility to both spontaneous and Fasmediated apoptosis. GrB was expressed by approximately one-fifth of CD8+ T cells. Compared with the CD8+ GrB- T-cell subset, the CD8+ GrB+ T-cell subset contained cells that were relatively more activated and more prone to spontaneous apoptosis. Culturing of cells with immunoglobulin M (IgM) anti-Fas monoclonal antibody had no additional effect on the number of CD8+ GrB+ T cells undergoing apoptosis. We suggest that the presence of CD8+ GrB+ T cells in peripheral blood from healthy individuals results from immune surveillance or contact with infectious agents, and that spontaneous apoptosis of these cells might serve as a mechanism for their eventual clearance.

Antibodies, Monoclonal↗
PubMed1998

Reduction of circulating secretory phospholipase A2 levels by anti-tumor necrosis factor chimeric monoclonal antibody in patients with severe Crohn's disease. Relation between tumor necrosis factor and secretory phospholipase A2 in healthy humans and in active Crohn's disease.

BACKGROUND: Secretory phospholipase A2 group II (sPLA2-II) has pro-inflammatory effects. The importance of tumor necrosis factor (TNF) for induction of plasma sPLA2-II in humans was studied in two groups of subjects. SUBJECTS: Six healthy volunteers received a single intravenous injection of recombinant human TNF or isotonic saline at random. Ten patients with active Crohn's disease received a single intravenous infusion of an anti-TNF chimeric monoclonal antibody, cA2. RESULTS: TNF infusion in healthy volunteers resulted in an increase of sPLA2-II at 3 h, with a maximal plasma level at 6 h (20.8+/-8.9 ng/ml; P < 0.05). In Crohn's disease base-line sPLA2-II levels were 33.9+/-13.4 ng/ml 24 h after infusion of cA2, 11.0+/-2.9 ng/ml (P < 0.005). Further decrease occurred in all except two patients at 2 weeks. The decrease in plasma sPLA2-II preceded all clinical signs of remission. CONCLUSION: TNF infusion in healthy humans can induce a rapid increase of circulating sPLA2-II, and selective blocking of TNF-alpha with cA2 results in a rapid decrease in sPLA2-II in peripheral blood. These data confirm that TNF has an important role in regulating the release of sPLA2-II in systemic and local inflammatory reactions.

Adult↗
PubMed1998

Apoptotic tubular cell death during acute renal allograft rejection.

Tubular cells are important targets during acute renal allograft rejection and induction of apoptosis might be a mechanism of tubular cell destruction. Susceptibility to induction of apoptosis is regulated by the homologous Bcl-2 and Bax proteins. Expression of Bcl-2 and Bax is regulated by p53, which down-regulates expression of Bcl-2, while simultaneously up-regulating expression of Bax. We studied apoptotic tubular cell death in 10 renal allograft biopsies from transplant recipients with acute rejection by in situ end-labelling and the DNA-binding fluorochrome propidium iodide. Tubular expression of p53, Bcl-2 and Bax was studies by immunohistochemistry. Five renal allograft biopsies from transplant recipients with uncomplicated clinical course and histologically normal renal tissue present in nephrectomy specimens from 4 patients with renal adenocarcinoma served as control specimens. Apoptotic cells and apoptotic bodies were detected in tubular epithelia and tubular lumina in 9 out of 10 acute rejection biopsies. In control renal tissue, apoptotic cells were detected in 1 biopsy only. Compared to control renal tissue, acute renal allograft rejection was, furthermore, associated with a shift in the ratio of Bcl-2 to Bax in favour of Bax in tubular epithelia and increased expression of p53 in tubular nuclei. These observations demonstrate that apoptosis contributes in part to tubular cell destruction during acute renal allograft rejection. In accordance, the shift in the ratio of Bcl-2 to Bax in favour of Bax indicates increased susceptibility of tubular epithelia to induction of apoptosis. The expression of p53 in tubular nuclei during acute renal allograft rejection indicates the presence of damaged DNA, which can be important in initiation of part of the observed apoptosis. These findings elucidate part of the mechanisms controlling apoptotic tubular cell death during acute renal allograft rejection.

Adult↗
PubMed1997

Apoptosis of acinar cells in pancreas allograft rejection.

BACKGROUND: Recently it has been recognized that apoptosis of target cells may occur during liver and kidney allograft rejection and is probably induced by infiltrating cells. Pancreas rejection is also characterized by a cellular infiltrate, however, the occurrence of apoptosis has not been investigated. We assessed whether pancreas rejection was associated with apoptosis of target cells and an influx of granzyme B (GrB)-positive or CD68-positive cells. METHODS: Eighteen pancreas biopsies (10 of 18 with rejection) from 15 patients with a pancreas-kidney transplantation were stained with the in situ end-labeling method for apoptosis, and for CD3, GrB, and CD68. RESULTS: Significantly more apoptotic acinar cells were found in biopsies with rejection when compared with biopsies without rejection. No difference was observed between the groups for GrB+ or CD68+ cells. CONCLUSION: We conclude that pancreas rejection is associated with apoptosis of acinar cells, but not with an increased influx of GrB+ cells or macrophages.

Antigens, CD↗