Biomedical subjects

H Wolf

Publications and source records attributed to H Wolf.

At least 109 records · Page 6Linked to original sources

PubMed1999

Latency of Epstein-Barr virus is stabilized by antisense-mediated control of the viral immediate-early gene BZLF-1.

The ability of the Epstein-Barr virus (EBV) to avoid lytic replication and to establish a latent infection in B-lymphocytes is fundamental for its lifelong persistence and the pathogenesis of various EBV-associated diseases. The viral immediate-early gene BZLF-1 plays a key role for the induction of lytic replication and its activity is strictly regulated on different levels of gene expression. Recently, it was demonstrated that BZLF-1 is also controlled by a posttranscriptional mechanism. Transient synthesis of a mutated competitor RNA saturated this mechanism and caused both expression of the BZLF-1 protein and the induction of lytic viral replication. Using short overlapping fragments of the competitor, it is shown that this control acts on the unspliced primary transcript. RT-PCR demonstrated unspliced BZLF-1 RNA in latently infected B-lymphocytes in the absence of BZLF-1 protein. Due to the complementarity of the gene BZLF-1 and the latency-associated gene EBNA-1 on the opposite strand of the genome, we propose an antisense-mediated mechanism. RNase protection assays demonstrated transcripts in antisense orientation to the BZLF-1 transcript during latency, which comprise a comparable constellation to other herpesviruses. A combined RNAse protection/RT-PCR assay detected the double-stranded hybrid RNA, consisting of the unspliced BZLF-1 transcript and a noncoding intron of the EBNA-1 gene. Binding of BZLF-1 transcripts is suggested to be an important backup control mechanism in addition to transcriptional regulation, stabilizing latency and preventing inappropriate lytic viral replication in vivo.

B-Lymphocytes↗

PubMed1999

Clinical outcome and follow-up of sonographically suspected in utero urinary tract anomalies.

PURPOSE: We determined the outcome of pregnancy and long-term renal function in cases of sonographically detected fetal urinary tract anomalies (UTAs). METHODS: This was a retrospective cohort study done at an academic hospital (tertiary referral center). All records of prenatal sonographic examinations done between January 1985 and October 1994 that indicated a suspicion for UTA were examined for perinatal mortality, postnatal confirmation of sonographic diagnosis, postnatal management, and calculated creatinine clearance to determine the ultimate renal function. RESULTS: Of 99 cases with suspected UTAs, 28 pregnancies were terminated because the UTA was considered fatal, and 32 fetuses died perinatally. Twenty-one children are alive with good renal function, 4 with moderate renal function, and 2 with poor renal function. The prenatal diagnosis was not confirmed after birth in 12 children, all of whom are alive with good renal function. The prognosis for prenatally suspected UTA was worse in cases of bilateral involvement and in cases with associated multiple malformations. CONCLUSIONS: The prognosis of prenatally diagnosed UTAs depends on the specific anomaly suspected. Abnormal karyotype, other associated malformations, and bilateral involvement are unfavorable determinants of the prognosis in individual cases.

Cohort Studies↗

PubMed1999

A comprehensive protein resource for the study of bladder cancer: http://biobase.dk/cgi-bin/celis.

In our laboratories we are exploring the possibility of using proteome expression profiles of fresh bladder tumors (transitional cell carcinomas, TCCs; squamous cell carcinomas, SCCs) and random biopsies as fingerprints to subclassify histopathological types and as a starting point to search for protein markers that may form the basis for diagnosis, prognosis, and treatment. Ultimately, the goal of these studies is to identify signaling pathways and components that are affected at various stages of bladder cancer progression and that may provide novel leads in drug discovery. Here we present our ongoing efforts to establish comprehensive two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) databases of TCCs and SCCs which are being constructed based on the proteomic and immunohistochemical analysis of hundreds of fresh tumors, random biopsies and cystectomies received shortly after operation (http://biobase.dk/cgi-bin/celis).

Animals↗

PubMed1999

Psoriasin (S100A7): a putative urinary marker for the follow-up of patients with bladder squamous cell carcinomas.

To search for bladder squamous cell carcinoma markers that are released to the urine a blind and systematic analysis of the protein profiles of fresh tumors, their secreted proteins, as well as the patient's urine was carried out using state-of-the-art proteomic technology. We review the data concerning the putative marker psoriasin (S100A7), which, alone or in combination with other biomarkers, may be valuable for the noninvasive follow-up of patients bearing these tumors.

Biomarkers, Tumor↗

PubMed1999

Short-term culturing of low-grade superficial bladder transitional cell carcinomas leads to changes in the expression levels of several proteins involved in key cellular activities.

Fresh, superficial transitional cell carcinomas (TCCs) of low-grade atypia (3 grade I, Ta; 6 grade II, Ta), as well as primary cultures derived from them were labeled with [35S]methionine for 16 h, between 2 and 6 days after inoculation. Whole protein extracts were subjected to IEF (isoelectric focusing) two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) followed by autoradiography. Proteins were identified by a combination of proteomic technologies that included microsequencing, mass spectrometry, 2-D PAGE immunoblotting and comparison with the bladder TCC protein database available on the internet (http://biobase.dk/cgi-bin/celis). Comparison of the IEF 2-D gel protein profiles of fresh tumors and their primary cultures showed that the overall expression profiles were strikingly similar, although differing significantly in the levels of several proteins whose rate of synthesis was differentially regulated in at least 85% of the tumor/culture pairs as a result of the short-term culturing. Most of the proteins affected by culturing were upregulated and among them we identified components of the cytoskeleton (keratin 18, gelsolin and tropomyosin 3), a molecular chaperone (hsp 28), aldose reductase, GST pi, metastasin, synuclein, the calreticulin precursor and three polypeptides of unknown identity. Only four major proteins were downregulated, and these included two fatty acid-binding proteins (FABP:FABP5 and A-FABP) which are thought to play a role in growth control, the differentiation-associated keratin 20, and the calcium-binding protein annexin V. Proteins that were differentially regulated in only some of the cultured tumors included alpha-enolase, triosphosphate isomerase, members of the 14-3-3 family, hnRNPs F and H, PGDH, hsp (heat-shock protein) 60, BIP, the interleukin-1 receptor antagonist, the nucleolar protein B23, as well as several proteins of yet unknown identity. The suitability of in vitro bladder tumor culture models to study complex biological phenomena such as malignancy and invasion is discussed.

Carcinoma, Transitional Cell↗

PubMed1999

[Multiplanar spiral CT in the diagnosis of pancreatic tumors].

PURPOSE: Investigation of the capabilities of MSCT and its value for the staging of pancreatic carcinomas. METHODS: 50 Patients with suspected pancreatic carcinoma were examined with a biphasic multislice-spiral-CT protocol: slice collimation 4 x 1 mm, Pitch 3.5-4 mm. After administration of 120 ml contrast medium and 50 ml NaCl with a flow rate of 3.0 ml/s the examination was started with a delay of 40 s (pancreatic phase) and 80 s (portal venous phase). RESULTS: Multislice spiral CT allows the examination of the whole upper abdomen with nearly isotropic data sets. This is the premise for the optimal assessment of the tumor extent in all planes, excellent demarcation of the tumor against the adjacent vessels and organs and the demarcation of small peripancreatic lymph nodes. CONCLUSIONS: Multislice spiral CT and the use of interactive multiplanar reconstructions improve the staging of pancreatic cancer.

Administration, Oral↗

PubMed1999

Dose reduction in CT by on-line tube current control: principles and validation on phantoms and cadavers.

We investigated approaches to reducing the dose in CT without impairing image quality. Dose can be reduced for non-circular object cross-sections without a significant increase in noise if X-ray tube current is reduced at angular tube positions where the X-ray attenuation by the patients is small. We investigated different schemes of current modulation during tube rotation by simulation and phantom measurements. Both pre-programmed sinusoidal modulation functions and attenuation-based on-line control of the tube current were evaluated. All relevant scan parameters were varied, including constraints such as the maximum modulation amplitude. A circular, an elliptical and two oval water phantoms were used. Results were validated on six cadavers. Dose reduction of 10-45% was obtained both in simulations and in measurements for the different non-circular phantom geometries and current modulation algorithms without an increase in pixel noise values. On-line attenuation-based control yielded higher reductions than modulation by a sinusoidal curve. The maximal dose reduction predicted any simulations could not be achieved due to limits in the modulation amplitude. In cadaver studies, a reduction of typically 20-40% was achieved for the body and about 10% for the head. Variations of our technique are possible; a slight increase in nominal tube current for high-attenuation projections combined with attenuation-based current modulation still yields significant dose reduction, but also a reduction in the structured noise that may obscure diagnostic details. We conclude that a significant reduction in dose can be achieved by tube current modulation without compromising image quality. Attenuation-based on-line control and a modulation amplitude of at least 90% should be employed.

Cadaver↗

PubMed1999

High prevalence of hemostatic abnormalities in women with a history of severe preeclampsia.

OBJECTIVE: In patients with a history of severe preeclampsia, an increased frequency of hemostatic abnormalities has recently been suggested in small studies without control groups. Our purpose was to investigate the prevalence of such abnormalities in a large patient group with a history of severe hypertensive disorder in pregnancy, in comparison with an appropriate control group. STUDY DESIGN: A total of 345 patients with a history of severe preeclampsia were investigated at a minimum of 10 weeks post partum for the presence of activated protein C resistance, the associated factor V mutation, hyperhomocysteinemia and anticardiolipin antibodies. The control group consisted of 67 healthy women with a history of uncomplicated pregnancies only. Blood was obtained during the second half of a normal menstrual cycle, and none of the patients or control subjects used oral contraceptives. RESULTS: Of all patients, 11.3% had activated protein C resistance (control subjects 1.5%, P =.025). Only half of these patients had the factor V mutation. Hyperhomocysteinemia was present in 12.1% of all patients, in comparison with 4.5% in the control group (P =.115). Anticardiolipin antibodies were observed in 20.9% of the patients, whereas these antibodies were found in 7.5% of the control subjects (P =.016). In general, the prevalence of these abnormalities was 1.5 to 2 times higher in patients who were delivered before 28 weeks, in comparison with patients who were delivered after 28 weeks. CONCLUSIONS: Hemostatic abnormalities, associated with an increased risk of thrombosis, are present in approximately 40% of patients with a history of severe preeclampsia, which is almost 4 times higher than in control subjects. These findings might suggest a cause of preeclampsia and could have implications in subsequent pregnancies and general health.

Antibodies, Anticardiolipin↗

PubMed1999

The effect of short-term immunotherapy with molecular standardized grass and rye allergens on eosinophil cationic protein and tryptase in nasal secretions.

BACKGROUND: Activation of mast cells and eosinophils under pollen exposure can be inhibited by specific immunotherapy. OBJECTIVE: The effect of short-term immunotherapy with 7 preseasonal injections of molecular standardized allergens from grass and rye pollen on eosinophil cationic protein (ECP) and tryptase levels in nasal secretions has been compared with symptomatic drug treatment in an open, randomized study with 48 patients. METHODS: Nasal reactivity and mediator levels in nasal secretions were measured at baseline, before season, in season, and after season. RESULTS: Symptom scores in the immunotherapy group were 134.5 (95% CI, 65 to 336) versus 386. 0 (95% CI, 185 to 563), significantly lower as in the drug-treated group. ECP and tryptase levels increased significantly during natural allergen exposition. The seasonal levels in the immunotherapy group were significantly lower than in the drug-treated group with 272.1 ng/mL (252.0 to 293.9 ng/mL; immunotherapy) versus 470.4 ng/mL (SEM, 435.6 to 508.0 ng/mL; drugs) for ECP and with 8.73 ng/mL (SEM, 8.20 to 9.29 ng/mL) versus 17.47 ng/mL (16.42 to 18.60 ng/mL) for tryptase (all, P <.001). The ECP level induced by nasal provocation was 105.6 ng/mL (99.0 to 112.6 ng/mL) versus 180.4 ng/mL (169.2 to 192.4 ng/mL), significantly lower (P <.001) in the immunotherapy group, as was the tryptase level with 12.12 ng/mL (11.53 to 12.75 ng/mL) versus 8.19 ng/mL (7. 79 to 8.62 ng/mL; P <.001) at the after-season visit. CONCLUSION: Short-term immunotherapy is able to reduce tryptase and ECP in nasal secretions more effectively than drug treatment in patients with allergic rhinitis.

Adolescent↗

PubMed1999

HIV-1 vaccine-induced immune responses which correlate with protection from SHIV infection: compiled preclinical efficacy data from trials with ten different HIV-1 vaccine candidates.

The specific immune mechanisms necessary and/or sufficient to elicit HIV-vaccine protection remain undefined. Utilising the SHIV rhesus macaque model the immunogenicity as well as the efficacy of ten different HIV-1 vaccine candidates was evaluated. Comparison of the immune responses induced, with the ability of the vaccine to protect from SHIV infection provided a means to determine which type of immune responses were necessary for protection. Vaccine candidates included VLPs, DNA, subunit protein with novel adjuvant formulations, ISCOMs and pox-virus vectors. Protection from SHIV infection was achieved in approximately half of the animals which received a primary intravenous cell-free challenge. The presence of CTL in the absence of other effector responses did not correlate with protection from this route and type of challenge. Virus neutralising antibodies (Nab) appeared to be necessary but alone were insufficient for protection. If Ag-specific IFN-gamma and/or IL-4 as well as lymphoproliferative (LP) responses were found with the lack of a detectable IL-2 response, then protection was not observed. Immunity correlated with the magnitude of Nab responses, beta-chemokines and as well as balanced, qualitative T-helper responses.

AIDS Vaccines↗

PubMed1999

High level expression of hepatitis B virus surface antigen in stably transfected Drosophila Schneider-2 cells.

Two transfer vector systems have been constructed for the generation of Drosophila melanogaster Schneider-2 (DS-2) cells transfected stably and used to express the small surface antigen of hepatitis B virus (HBsAg). One system is based on the cotransfection of an expression vector for the S gene under the control of an inducible Drosophila metallothionein (Mtn) promotor and a resistance plasmid which carries a selectable marker dihydrofolate reductase (dhfr) gene under the control of a Drosophila actin 5C distal promoter. The second system is based on the transfection of a single plasmid, which includes both expression units. Both vector systems were suitable for the generation of stably transfected DS-2 cell-lines secreting high levels of HBsAg. The quantities of HBsAg expression from polyclonal DS-2 cells correlated strictly with the concentration of the transfected S gene expression vector. Clonal cell-lines selected from the most efficient HBsAg producing polyclonal cell-populations were examined in more detail. All of the transfected S genes were found to be integrated and the copy numbers per genome varied extremely between 10 and 240. Furthermore, the levels of secreted HBsAg varied greatly between different clones and in best they reached up to 7 microg/ml under serum-free cell culture conditions. Thus, DS-2 cells transfected stably provide an alternative source for the production of HBsAg particles for diagnostic purposes and vaccine development.

Animals↗

PubMed1999

Purification and characterization of hepatitis B virus surface antigen particles produced in Drosophila Schneider-2 cells.

The small surface antigen of hepatitis B virus (HBV) was produced in Drosophila melanogaster Schneider-2 (DS-2) cells transfected stably using an inducible Drosophila metallothionein promoter. Selected clonal DS-2 cell-lines expressed and secreted large quantities of HBsAg particles consisting exclusively of non-glycosylated 25 kDa proteins. HBsAg produced by DS-2 cells had physical and biochemical properties very similar to 22 nm particles derived from the human hepatoma cell-line PLC/PRF/5. DS-2 cell-derived HBsAg particles were purified near homogeneity by a strategy based on protein concentration, precipitation and ultracentrifugation. The resulting HBsAg product was < 98% pure. A single immunisation of BALB/c mice with both DS-2 and yeast-cell derived purified HBsAg particles without adjuvants elicited a substantial humoral antibody and class-I restricted cytotoxic T lymphocyte (CTL) response. Adsorption of HBsAg particles to aluminium hydroxide resulted in increased levels of HBsAg-specific antibodies. However, CTLs were not elicited by HBsAg/Alum combinations. Thus, stably transfected DS-2 cells provide a useful source for the production of HBV subviral particles for diagnostic and research purposes as well as for novel vaccine development.

Animals↗

PubMed1999

Accelerated clearance of SHIV in rhesus monkeys by virus-like particle vaccines is dependent on induction of neutralizing antibodies.

Recombinant, insect cell derived SIV Pr56(gag) virus-like particles (VLPs) have been modified either by inserting HIV-1 Gp160 derived peptides into the Pr56(gag) precursor or by integrating the complete HIV-1 gp120 in the particle membrane. To investigate the protective efficacy of these particulate antigens, rhesus macaques were immunized with VLPs both adjuvant-free or adsorbed to alum. In addition, recombinant Semliki Forest viruses (SFV) expressing proteins corresponding to the VLP constructs were established and administered as live vaccines in combination with particulate antigens. Vaccination induced specific humoral responses irrespective of the immunization regimen. However, in contrast to Pr56(gag)-specific antibodies, Env-specific antibody titers could not be increased by booster immunizations in this study. Cell-mediated immune responses were detected following vaccination with VLP-preparations as well as recombinant SFVs. A tendency towards stimulating both enhanced cell mediated as well as humoral immune responses was observed following priming with recombinant SFVs. Upon challenge with SHIV-4 all vaccinated monkeys became infected. However, animals, that were vaccinated with VLPs presenting the complete gp120, managed to clear virus faster than nonimmunized controls. The observed virus elimination significantly correlated with an anamnestic antibody response and an accelerated appearance of neutralizing antibodies postchallenge.

AIDS Vaccines↗

PubMed1999

School performance and behaviour in extremely preterm growth-retarded infants.

OBJECTIVE: To describe school performance and behaviour of extremely preterm, growth-retarded infants. DESIGN: Cohort study at two tertiary care centres. Included were all surviving, singleton infants (N= 127) with fetal growth retardation due to placental insufficiency. All were delivered by caesarean section because of signs of fetal distress before the beginning of labour at a gestational age of 26 to 32 weeks during the years 1984-1989. Main outcome measures were special education, mainstream education below the appropriate age level and behaviour according to attention-deficit hyperactivity criteria at school age (4 1/2-10 1/2 yrs). The children were divided into two subgroups according to age at follow-up (> or =7 1/2 and <7 1/2 yr). A logistic regression analysis was performed with special school or repeating a grade and behavioural disturbance as dependent variables and gestational age, birth weight, sex of the infant, neonatal complications (intra cerebral haemorrhage, respiratory distress syndrome, bronchopulmonary dysplasia or sepsis), age category at follow-up and sociodemographic factors as independent variables. RESULTS: 114 (90%) had a complete follow-up. Special education was found in 14% of the assessed children. More children in the older age group than in the younger age group were placed in special school (20% versus 10%). Behavioural problems were scored in 39% of the assessed children attending mainstream education. Special education was related to neonatal complications (bronchopulmonary dysplasia), behavioural problems to the absence of either parent. CONCLUSION: This specific group of growth-retarded children is at serious disadvantage for adequate performance in school, although the incidence of special education and behavioural problems was comparable to other preterm infants. Both special education and behavioural problems were not related to obstetric variables as gestational age and/or birth weight.

Child↗

PubMed1999

Quartz crystal microbalance (QCM) as a device for the screening of phage libraries.

An immunosensing system based on a quartz crystal microbalance (QCM) is presented for the selection of both antigen specific recombinant antibodies and antigen specific human pancreatic secretory trypsin inhibitor (hPSTI) mutants isolated from large phage libraries. The QCM was integrated into a flow injection analysis system for the straightforward analysis of large sample numbers. Measurements were performed using a biotinylated antigen immobilized by streptavidin onto the gold surface of the quartz crystal and phages displaying recombinant antibodies or hPSTI mutants. The results obtained by the QCM were in accordance to those of a well established enzyme linked immunosorbent assay (ELISA). Therefore, the QCM is well suited for the detection of single high affinity clones isolated from large phage display libraries.

Bacteriophages↗

PubMed1999

Acute parvovirus B19 infection in connection with a flare of systemic lupus erythematodes in a female patient.

BACKGROUND: Since its discovery parvovirus B19-infections could be linked to a growing variety of diseases. Besides the harmless exanthema erythema infectiosum perferentially observed with B19-infections in childhood a panel of rather serious and also chronic courses that may be associated with anemia, thrombocytopenia, arthritis and others have been described. OBJECTIVE: In a 26-year-old female patient an acute parvovirus B19-infection was followed by a serious episode of systemic lupus erythematosus (SLE). Here we demonstrate the clinical and serological parameters which were observed in the patient during that episode in addition to the nucleotide sequence of the virus isolate. RESULTS AND CONCLUSION: In this patient parvovirus B19 was not the initial causative agent for SLE. However the B19 infection was followed by a severe flare of SLE and therefore may be considered as an enhancer of the autoimmune disease. The amount of nucleotide variability observed in the viral genome was in the range known from other B19 isolates. An elevated degree of mutations in antigenic domains was not detectable. Therefore, we would like to emphasize the possible role of parvovirus B19 in the aetiology or the enhancement of autoimmune diseases like SLE and the necessity of an according differential diagnosis.

Adult↗

PubMed1999

Induction of abortive and productive proliferation in resting human T lymphocytes via CD3 and CD28.

How the T-cell receptor (TCR)/CD3 complex mediates positive as well as negative signals for T-cell regulation is not fully understood. We have previously described the induction of anergy in resting human T lymphocytes after mitogenic, high-dose CD3 triggering with monoclonal antibodies. Here we report the concomitantly occurring cell death to be largely caused by apoptosis, which mainly affects the CD4+ T-helper population. Because cell death becomes detectable after initial cell proliferation, it appears that a high-dose CD3 stimulus constitutes a negative signal for resting T cells leading to an 'abortive proliferation' that is followed by anergy and/or apoptosis of the cells. In contrast, if initial proliferation is induced by a low dose of anti-CD3 in the presence of an accessory signal via the CD28 receptor, anergy and cell death are markedly reduced and 'productive proliferation' may occur. Productive proliferation is characterized by an increased secretion of various cytokines measured (interleukin (IL)-2, IL-4, IL-6, IL-10, tumour necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma)). A low-dose submitogenic CD3 stimulus induced neither anergy nor cell death, supporting the view that negative CD3 signalling requires proliferation of resting cells.

Apoptosis↗

PubMed1999

[Dosage reduction in computed tomography by anatomy-oriented attenuation-based tube-current modulation: the first clinical results].

PURPOSE: To examine the feasibility of reducing exposition in CT examinations by applying a prototype device for tube current modulation with the image quality remaining unchanged. PATIENTS AND METHODS: The prototype device for tube current modulation was integrated into a Somatom Plus 4 CT scanner (Siemens). The method is based on anatomy-oriented modulation of the tube current. The attenuation of the X-ray beam by the patient's body was determined online, the tube current was adapted to changing anatomy after a delay of 180 degrees. In ten patients undergoing radiotherapy, four identical scans of the shoulder region were carried out with and without tube current modulation. For determining dose reduction, mAs product of both scans were compared. The evaluation of noise artifacts, low contrast detectability and overall image quality was performed by four radiologists in a blinded fashion. RESULTS: Patient doses could be reduced by 38% on an average. Scans with tube current modulation were superior to scans without it as to noise (75%), low contrast detectability (51%), artifacts (69%), and overall image quality (71%). CONCLUSIONS: A significant reduction in exposition during CT can be achieved by anatomy-oriented tube current modulation without image degradation.

Artifacts↗