PubMed Health⌕ Search

Biomedical subjects

D Wilhelm

Publications and source records attributed to D Wilhelm.

At least 37 records · Page 2Linked to original sources
PubMed1996

Chemokines in stored platelet concentrates.

BACKGROUND: Platelets contain several mediators, belonging to a family of proinflammatory cytokines named chemokines, that are stored in the organelles. Release and accumulation of these chemokines during storage of platelet concentrates (PCs) might be responsible for nonhemolytic transfusion reactions. STUDY DESIGN AND METHODS: Analysis was done of pH and the levels of platelet factor 4, beta-thromboglobulin, interleukin 8, RANTES, macrophage-inflammatory protein-1 alpha, lactate dehydrogenase, and serotonin in the supernatant of stored PCs on Days 1, 3, 5, and 8. PCs were prepared by apheresis or from pools of four buffy coats. Buffy coat PCs were filtered before storage. RESULTS: Nonfiltered apheresis PCs, which had a higher white cell contamination (p < 0.01), contained significantly more platelets than did buffy coat PCs (p = 0.02). The pH decreased significantly in apheresis PCs (p = 0.01), whereas there was a significant increase in lactate dehydrogenase (p < 0.001). In buffy coat PCs, pH remained stable and lactate dehydrogenase increased moderately. Concentrations of platelet factor 4 and beta-thromboglobulin increased steadily in both preparations over the storage period (p < 0.001). Macrophage-inflammatory protein-1 alpha was hardly detectable in the supernatant of both PCs, while RANTES levels increased significantly with storage time (p < 0.001). Interleukin 8 was not found in the supernatant of any PCs, with the exception of one apheresis PC with high white cell contamination (> 10(9)/ L). Serotonin levels were higher in apheresis PCs (p = 0.01), but the levels did not correlate with storage time. CONCLUSION: Platelet factor 4, beta-thromboglobulin, and RANTES were released from platelets during storage and accumulated over time in the PCs. These chemokines might play a causative role in nonhemolytic transfusion reactions because of their inflammatory potential, but the clinical effects of the transfusion of PCs with high chemokine contents remain to be investigated.

Blood Platelets↗
PubMed1995

Stimulation of c-Jun activity by CBP: c-Jun residues Ser63/73 are required for CBP induced stimulation in vivo and CBP binding in vitro.

The CBP protein mediates PKA induced transcription by binding to the PKA phosphorylated activation domain of CREB. Here we show that CBP also stimulates the activity of both c-Jun and v-Jun in vivo. The CREB binding domain of CBP is sufficient to contact to c-Jun in vitro. When this domain of CBP is linked to the activation domain of VP16 and expressed in vivo it stimulates c-Jun dependent transcription. Deletion analysis of c-Jun indicate that the CBP binding site is within the N-terminal activation domain. Loss of binding to CBP in vitro correlates with severely reduced transactivation capacity in vivo. Mutation of Ser63/73 in c-Jun, or the corresponding position in v-Jun (Ser36/46) leads to reduced binding to CBP in vitro and abolishes augmentation of transcription in vivo. These data are consistent with a mechanism by which CBP acts as a co-activator protein for Jun dependent transcription by interacting with the Jun N-terminal activation domain.

Binding Sites↗
PubMed1995

ATF-2 is preferentially activated by stress-activated protein kinases to mediate c-jun induction in response to genotoxic agents.

The major regulators of the c-jun promoter are ATF-2 and c-Jun. They act as pre-bound heterodimers on two 'AP-1-like' sites, and are preferentially addressed by different types of extracellular signals. The transactivating potential of ATF-2 is stimulated to a higher extent than that of c-Jun by a broad group of agents causing DNA damage and other types of cellular stress, such as short-wavelength UV, or the alkylating compounds N-methyl-N'-nitro-N-nitroso-guanidine (MNNG) or methylmethanesulphonate (MMS). In contrast, treatment with the phorbol ester TPA preferentially enhances c-Jun-dependent transactivation but does not affect ATF-2. Accordingly, UV and MMS but not TPA induce c-jun transcription in F9 cells, which express ATF-2, but not c-Jun. Stimulation of ATF-2-dependent transactivation by genotoxic agents requires the presence of threonines 69 and 71 located in the N-terminal transactivation domain. These sites are the target of p54 and p46 stress-activated protein kinases (SAPKs) which bind to, and phosphorylate ATF-2 in vitro. However, p46 and p54 kinase activity is not increased by phorbol ester, which strongly suggests that the protein kinase phosphorylating c-Jun in response to TPA is distinct from SAPKs and does not act on ATF-2. Our data demonstrate that distinct signal transduction pathways converge at c-Jun/ATF-2, whereby each subunit is individually addressed by a specific class of protein kinases. This allows fine tuned modulation of c-jun expression by a large spectrum of extracellular signals.

Activating Transcription Factor 2↗
PubMed1995

Detection of the chemokine RANTES in cytokine-stimulated human dermal fibroblasts.

A novel family of structurally and functionally related polypeptides has recently been detected that are now referred to as chemokines. Within this family, a peptide with the acronym RANTES was shown to be chemotactic for memory T cells, monocytes, and eosinophilic and basophilic granulocytes, thus suggesting it plays an important role in chronic inflammatory and allergic diseases. Murine monoclonal antibodies as well as cDNA probes specific for human RANTES were raised and extensively characterized. With these antibodies, stimulated human dermal fibroblasts were shown to express intracellular RANTES peptide by immunocytochemistry. Furthermore, similar kinetics could be demonstrated in fibroblasts for both RANTES mRNA expression and secretion of RANTES peptide using Northern blot hybridization and sandwich-enzyme-linked immunosorbent assay, respectively. RANTES expression was induced upon stimulation with tumor necrosis factor-alpha as well as with interleukin-1 alpha and -beta in a concentration- and time-dependent manner. These results reinforce the role of both resident and circulating cells in the production and release of RANTES and their participation in inflammatory processes.

Antibodies, Monoclonal↗
PubMed1995

Cytokines in platelet concentrates prepared from pooled buffy coats.

Platelet concentrates (PC) prepared from pooled buffy coat (BC-PC) contain a variable number of leukocytes from different donors. We questioned whether storage of BC-PC can lead to a lymphocyte activation in the sense of a mixed lymphocyte reaction. BC-PC were prepared from four ABO-identical buffy coats and we undertook leukocyte analyses and measurement of different cytokines on days 1, 3 and 5 of PC storage (n = 72). Cytokine content was also determined in freshly prepared plasma (n = 48) and PC prepared by thrombapheresis (SD-PC) (n = 12). As control, we studied lymphoproliferation of pooled peripheral blood mononuclear cells from four individuals in 10 mixed lymphocyte cultures (MLCs) under optimal conditions. In the BC-PC, whole blood count and lymphocyte analysis showed a mean leukocyte contamination of 64 +/- 28 x 10(6) per unit with a proportion of lymphocytes of 66.7 +/- 13%. In the MLC, levels of interleukin-2 (IL-2) and interferon-gamma (IFN-gamma) were increased on day 3 and 5 of storage (p < 0.001). In a proportion of BC-PC, tumor necrosis factor-alpha (72.2%) and IL-2 (43.1%) were detectable immediately after preparation, whereas IFN-gamma (4.2%), interleukin-1 beta (4.2%) and interleukin-8 (11.1%) were only found in some BC-PC. In all cases, initial values of cytokines did not increase during storage. Cytokine measurement in FFP and SD-PC showed similar results. The study demonstrates that cytokines are detectable in a variety of blood products immediately after preparation.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Platelets↗
PubMed1995

Impact of allergy screening for blood donors: relationship to nonhemolytic transfusion reactions.

There has been some discussion whether the atopic disposition of a blood donor is associated with a potentially higher incidence of hypersensitivity nonhemolytic transfusion reactions (NHTRs). Serum samples from patients who had suffered from NHTRs and samples from the platelet concentrates (PCs) responsible for the reactions were examined for total and specific IgE as diagnostic markers for allergic events. In addition, the allergy prevalence among 1,088 blood donors was determined to analyze the allergy prevalence among our blood donors. Our results indicate that in 90% of cases, allergic NHTRs were associated with specific IgE antibodies in the recipient's serum, indicating the allergic disposition of the patient. In contrast, specific IgE antibodies were detected in only 22% in the transfused PCs. However, among all investigated NHTRs, there was not a single case in which specific IgE antibodies were detected exclusively in the PC. The allergy prevalence among our blood donors was about 26%. In our opinion, the few cases in which the allergic disposition of blood donors in combination with the allergic disposition of the recipients was associated with NHTRs reflects the allergy prevalence among our blood donors in general (26%). On the basis of these findings, we conclude that allergy diagnosis for blood donors is only of minor value in the prevention and prediction of NHTRs, whereas allergy diagnosis for patients who require multiple PC transfusion might be helpful.

Antibody Specificity↗
PubMed1995

Immunocytochemical localization of the chemokines RANTES and MIP-1 alpha within human platelets and their release during storage.

The cytokines RANTES and MIP-1 alpha are 8-kD peptides which belong to the C-C subfamily of chemokines. They are both potent chemotactic factors for basophils and eosinophils. Apart from lymphocytes, the RANTES peptides was recently shown to be released from human platelets stimulated with thrombin [Kameyoshi et al: J Exp Med 1992;176:587-592]. Employing postembedding immunocytochemistry, we could detect RANTES and for the first time also MIP-1 alpha within the alpha-granules of human platelets. To date, MIP-1 alpha was not reported to occur in platelets. In slightly activated platelets, as found in stored platelet concentrates (PC), label for RANTES and MIP-1 alpha could also be observed within cisterns of the open canalicular system and on the plasma membrane, indicating a release of both peptides. These findings were confirmed by in vitro studies in PC, by investigation of RANTES and MIP-1 alpha release into the suspending medium. Over a period of 8 days, RANTES was steadily released in relatively high amounts, whereas MIP-1 alpha was measured in rather small amounts in the suspending medium. As RANTES and MIP-1 alpha, besides their chemotactic activity on eosinophils and basophils, are able to mediate the release of histamine, it is tempting to speculate about a participation of platelets in inflammatory reactions in which eosinophils and basophils are involved.

Animals↗
PubMed1995

Subclass typing of IgG paraproteins by immunofixation electrophoresis.

We present a simple method for subclass typing of IgG paraproteins, with which we have demonstrated a large number of paraproteins that were undetected by conventional immunofixation techniques. The types and distribution of IgG subclass paraproteins were analyzed in 92 human sera in which IgG paraproteins had been demonstrated. The IgG subclass paraproteins were separated by agarose gel electrophoresis rapidly and simply and then typed with the use of sheep anti-human monospecific IgG1-IgG4 antibodies. In 24 of the sera analyzed, IgG subclass typing revealed 25 additional monoclonal bands that were not detected by conventional immunofixation electrophoresis with anti-IgG antisera. Most of these belonged to a different subclass type. The overall subclass frequencies were 68% IgG1, 13% IgG2, 16% IgG3, and 3% IgG4. The distribution of paraprotein subclasses, however, was different in monoclonal gammopathies of undetermined significance in which more IgG3 was shown, whereas in non-Hodgkin lymphomas the number of IgG2 paraproteins was greater than expected; this finding may have diagnostic and prognostic significance.

Antibodies, Monoclonal↗
PubMed1994

[Sex and age-dependent gaps in tetanus immunization].

To test tetanus immunity, tetanus antitoxin titres were measured in the serum of 692 subjects (354 males, 338 females), aged one day (newborns) to 92 years (mean age 29 years). Those aged 18 to 65 years were first-time blood donors, the remainder were healthy newborns, while the children and those over 65 years were patients without immune-compromising disease. An inadequate protection (titre < 0.1 IU/ml) was found in 107 (15.5%), of whom 75 (70%) were females. Women aged 20 years and above also had significantly lower average antitoxin titres than men (1.7 vs. 3.5 IU/ml); P < 0.0001). The inadequate immunization protection of many young women is reflected in the lack of protective antibodies in 10 of the 49 examined newborns. In addition, 18% of children aged between 1 and 15 years had inadequate immunity against tetanus. In the whole group the titre level decreased with age, while the proportion of unprotected persons increased. Apart from the obvious age and sex dependency of the demonstrated inadequacy of immunological protection against tetanus, attention should also be paid to the lack of protective antibodies in newborns and the marked gaps of immunity among children.

Adolescent↗
PubMed1994

Expression of sCD23 in atopic and nonatopic blood donors: correlation with age, total serum IgE, and allergic symptoms.

Although structure, biologic activities, and expression of the low-affinity IgE receptor (FceRII, CD23) have been investigated, the diagnostic value for allergies of this molecule and its soluble circulating fragment (sCD23) remains unclear. Therefore, serum sCD23 levels were measured in 203 blood donors. They were divided into atopic and nonatopic subjects by allergy history, physical findings of allergic symptoms, and corresponding specific circulating IgE antibodies. The group consisting of nonatopic subjects was divided into four age categories in order to exclude age-dependent variations in the expression of the low-affinity IgE receptor. In our study population, sCD23 serum levels were not influenced by age. Furthermore, no significant differences, especially no decrease in serum sCD23 levels, between the four nonatopic age groups were detected. There was no significant increase of sCD23 serum levels in atopic subjects in comparison with nonatopic blood donors. In addition, no correlation between total IgE levels and sCD23 serum levels could be detected, in either the group of atopic donors or the group of nonatopics. Our data suggest that the circulating low-affinity IgE receptor does not appear to be an additional general marker for the diagnosis of allergies, as previously suggested.

Adult↗
PubMed1994

[Cytokines, immunoglobulins, and IgG subclasses in patients with IgG plasmacytomas].

Cytokines play an essential role in normal and malignant B-cell proliferation and isotype-switching. Therefore we determined serum levels of different B-cell activating cytokines including IFN gamma, IL-4 and IL-10, IgG subclasses, further immunoglobulins and the soluble B-cell activation marker sCD23 in 68 patients with recently diagnosed and previously untreated IgG myelomas in comparison with age- and sex-matched healthy controls. Our results demonstrated that 16% of the myeloma patients had elevated IL-10 levels up to 1000 pg/ml and 8% showed increased IFN gamma serum concentrations. By contrast, only 7% of the controls showed detectable IL-10 levels and 3% had measurable IFN gamma levels. While in men 67% of the paraproteins were of the kappa light chain type, we found an equal occurrence of kappa and lambda light chains in women. In addition, the distribution of IgG subclasses differed in men and women. In comparison with the controls, no alteration of sCD23 was detected in myeloma patients. We found an apparent correlation of elevated IL-10 levels and the IgG1 subclass.

Aged↗
PubMed1994

Immediate-type hypersensitivity reactions after platelet transfusion.

Non-febrile non-haemolytic transfusion reactions (NHTR) after platelet substitution vary from severe (anaphylactic shock) to mild (urticaria) forms. Although the symptoms of these immediate-type hypersensitivity reactions are well documented, little is known about their pathophysiology. We therefore examined sera from patients suffering from different forms of NHTR regarding total serum IgE, specific IgE antibodies and complement activity. Our results show that specific IgE antibodies in the recipients' sera were clearly associated with immediate-type hypersensitivity NHTR and conclude that atopic patients have a higher risk of suffering from these forms of transfusion reactions than non-atopic patients. Allergy diagnostic for patients who require platelet transfusions should be considered in case of multiple platelet substitution.

Complement System Proteins↗
PubMed1993

Functional study on the effects of nifedipine, cromakalim, and the absence of extracellular Ca2+ on alpha 1-adrenoceptor-mediated excitation-contraction coupling in isolated rat portal vein: comparison with depolarization-mediated excitation-contraction coupling.

The effects of Ca(2+)-entry blockade by nifedipine, K+ channel opening by cromakalim, and of omitting extracellular Ca2+ on the contractile response elicited by a supramaximum concentration of the "full" and selective alpha 1-adrenoceptor agonist phenylephrine (10(-4) M) were compared with those elicited by a supramaximal concentration of KCl (50 mM) in isolated rat portal vein. The contractile response to phenylephrine appeared to be biphasically composed of an early "transient" phase and a slowly developing "sustained" phase that reached maximum values after 30 s and 5 min after initiation of contraction, respectively. The contractile response to KCl (50 mM) exhibited a triphasic pattern consisting of "spike," "transient", and "sustained" components that peaked after 8 s, 25 s, and 10 min, respectively. Nifedipine was able to eliminate all components of the contractions in response to both phenylephrine and KCl almost completely. Nifedipine was approximately 10 times more potent at suppressing the slowly developing sustained components of the contractions in response to both stimuli than the early transient components. The spontaneous myogenic contractions were inhibited by nifedipine with intermediate potency. Cromakalim, in contrast to nifedipine, selectively eliminated the early transient components of the contractions in response to both phenylephrine and KCl. The sustained components of the contractions in response to both stimuli were relatively resistant to K+ channel opening, although higher concentrations (> 1 microM) of cromakalim were capable of antagonizing the sustained response to phenylephrine accompanied by oscillations in tone. Cromakalim was most potent in counteracting spontaneous myogenic contractions. When phenylephrine and KCl were added with or without external Ca2+ after different periods of equilibration in nominally Ca(2+)-free medium, different washout kinetics for the different components of the contractions in response to both stimuli were observed. The early transient phases of tension development in response to both stimuli were completely lost after approximately 6 min of equilibration in nominally Ca(2+)-free medium, whereas the slowly developing sustained components of the contractions were immediately lost after the change to nominally Ca(2+)-free medium. Externally added Ca2+, when administered together with phenylephrine or KCl after the preparations had been exposed for different times to nominally Ca(2+)-free medium, could not restore the early transient components.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1993

T cells and their role in allergies.

The molecular and cellular mechanisms which up-regulate IgE synthesis in most atopic patients are only incompletely understood. There is no doubt that T cells play a prominent role in the B cell immunoglobulin switch to IgE. T-cell-derived interleukin (IL)-4 is a specific inducer of IgE synthesis which activates B cells to proliferate and, furthermore, induces other cells to release cytokines which enhance IgE synthesis. Additional costimulatory signals are required, however, for B cell activation and the consequent immunoglobulin switch to IgE. Besides physical B/T cell interaction, direct B cell activation through anti-CD40 provides such a signal. IL-4-induced B cell activation is amplified by other cytokines such as IL-5, IL-6, IL-3, probably IL-9, and tumor necrosis factor-alpha, whereas interferon (IFN)-gamma, IFN-alpha, transforming growth factor-beta and IL-12 are able to inhibit IL-4-induced IgE synthesis. These different IgE-synthesis-modulating lymphokines are secreted by different T cell subsets, TH1 and TH2. While IgE synthesis is activated by TH2-derived lymphokines, TH1 cell clones exhibit cytolytic activity. The detection of allergen-specific T cells in peripheral blood mononuclear cells (PBMNCs) of atopic patients, with a lymphokine profile similar to TH2, and the predominance of TH2 cells in PBMNCs of these patients might be one explanation for increased serum IgE concentrations in atopic individuals. It is not known, however, which stimulus leads to a predominant expression of TH2 cells over TH1 cells in atopic patients with consequently increased IgE synthesis.

B-Lymphocytes↗
PubMed1993

[Interferon alpha antibodies show no cross reactions with typical autoantibodies].

Patients treated with natural human interferon alpha develop anti-interferon antibodies (IFN-AB) only in very rare cases. By contrast, patients with autoimmune disorders are able to generate high-titered IFN-AB against endogenous interferon alpha. One explanation for the development of auto-IFN-AB could be cross-reactivity with typical autoimmune antigens. We investigated the cross-reactivity of 3 high-titered IgG IFN-AB of female autoimmune patients (aged 32, 36, 74 years; two severe cases of SLE, one case of autoimmune thyroiditis) as well as 25 low-titered natural IgM IFN-AB of healthy blood donors (aged 19-48 years). Typical autoimmune antigens including dsDNA, ENA, as well as natural interferon beta and recombinant interferon gamma are not able to inhibit binding of IFN-AB to interferon alpha in an ELISA test system. Preincubation of sera containing either dsDNA antibodies (dsDNA-AB) (24 patients), thyroid peroxidase (TPO-AB) (9 patients) or thyroglobulin (TG-AB) (12 patients) with interferon alpha resulted in no change in the respective autoantibody titer. These data suggest that there is no cross-reactivity between IFN-alpha-AB and dsDNA-AB, TPO-AB or TG-AB. Thus, an explanation for the occurrence of IFN-AB in autoimmune disorders cannot be found in a cross-reaction between interferon alpha with typical autoimmune antigens.

Adult↗