Detection of <Emphasis Type="Italic">Pneumocystis</Emphasis>DNA in samples from patients suspected of bacterial pneumonia- a case-control study

Background  

Pneumocystis jiroveci (formerly known as P. carinii f.sp. hominis) is an opportunistic fungus that causes Pneumocystis pneumonia (PCP) in immunocompromised individuals. Pneumocystis jiroveci can be detected by polymerase chain reaction (PCR). To investigate the clinical importance of a positive Pneumocystis-PCR among HIV-uninfected patients suspected of bacterial pneumonia, a retrospective matched case-control study was conducted.     

Age-dependent deamidation of H1° histones in chromatin of mammalian tissues

The composition of the H1° histone subfractions was examined in different rat and mouse tissues. Using reverse-phase HPLC and hydrophilic-interaction liquid chromatography we have found that the relative proportions of all four forms of H1° differ from tissue to tissue and from species to species. In principle, we observed an age-dependent increase in the amount of both the N-terminally acetylated (H1°a Asn-3 and H1°a Asp-3) and the deamidated forms of H1° (H1°a Asp-3 and H1°b Asp-3). Compared with the proportion of N-terminally acetylated H1° forms in liver, kidney and brain of rats and mice 20 days of age, we found an increase in these H1° subfractions of up to 30% in the corresponding organs of 300-day-old animals. The proportion of deamidated H1° forms was 1.6- to 4-fold higher in the livers and 8- to 12-fold higher in the brains of 300-day-old mice and rats, respectively, than in 20-day-old animals. The tissue-specific nature of the ratio of H1° subfractions suggests that the different forms of histone H1° have specific individual functions. The possible biological significance of age-related accumulation of N-terminal acetylated and deamidated histone H1° forms is discussed in the light of our results. Received: 4 December 1998 / Accepted: 2 January 1999     

Comparison of GP IIB/IIIA Inhibitors and Their Activity as Measured by Aggregometry, Flow Cytometry, Single Platelet Counting, and the Rapid Platelet Function Analyzer

Background: GP IIb/IIIa inhibitors have primarily been used short-term e.g., during PTCA. They failed to show clinical benefit during long-term therapy. One reason might be the absence of a method to monitor inhibitor activity. This study compared platelet aggregometry, the rapid platelet function analyzer (RPFA) test, single platelet counting, and flow cytometric determination of receptor occupancy to measure GP IIb/IIIa-receptor inhibitor activity. Methods: Increasing doses of abciximab, tirofiban, and eptifibatide were added to whole blood in vitro. Whole blood was used for the RPFA, for single platelet counting and flow cytometry. Platelet rich plasma was prepared for aggregometry. Results: The correlation between aggregometry and RPFA results was linear for abciximab and eptifibatide. Tirofiban was a stronger inhibitor with the RPFA (IC₅₀ 7.7[emsp4 ]nM) than with aggregometry (IC₅₀ 19.6[emsp4 ]nM). The single platelet counting technique showed that even supratherapeutic concentrations of all three inhibitors could not completely suppress microaggregation. Abciximab concentrations that were equipotent to tirofiban with aggregometry were less potent with regards to the inhibition of microaggregation. This difference was more pronounced with TRAP induced microaggregation than with ADP. The flow cytometric receptor occupancy test showed that occupancy was 95[emsp4 ]% with 5[emsp4 ]g/ml abciximab and almost 97[emsp4 ]% with 10[emsp4 ]g/ml. Tirofiban reached a maximum receptor occupancy of 56[emsp4 ]%, eptifibatide 64[emsp4 ]%. Conclusions: While aggregometry is time consuming the RPFA provides results fast and with little variability. There is still a discrepancy between aggregometry and RPFA results for tirofiban. The single platelet counting technique detects the inhibition of microaggregation the relevance of which for the clinical outcome is not known. The flow cytometric receptor occupancy assay is best suited for abciximab.     

Mutations in Hepatitis D Virus Allow It to Escape Detection by CD8+ T Cells and Evolve at the Population Level

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Argatroban treatment for patients with intolerance to heparin and hirudin.

Argatroban is a synthetic thrombin inhibitor that acts independently of any cofactor. It inhibits free as well as fibrin- and clot-bound thrombin. The clinical history of two patients is presented, both with previous allergic reactions toward heparin and hirudin. In both patients, antibodies against hirudin were documented. Argatroban was successfully used in both patients without any side effects. We conclude argatroban to be the drug of choice in patients with intolerance to heparin and hirudin. Moreover, genetic variations affecting the hepatic catabolism of argatroban might exist, because very different dosages of argatroban were needed in the two patients.     

PPAR activators as antiinflammatory mediators in human T lymphocytes: implications for atherosclerosis and transplantation-associated arteriosclerosis

Activation of T lymphocytes and their ensuing elaboration of proinflammatory cytokines, such as interferon (IFN)-gamma, represent a critical step in atherogenesis and arteriosclerosis. IFNgamma pathways also appear integral to the development of transplantation-associated arteriosclerosis (Tx-AA), limiting long-term cardiac allograft survival. Although disruption of these IFNgamma signaling pathways limits atherosclerosis and Tx-AA in animals, little is known about inhibitory regulation of proinflammatory cytokine production in humans. The present study investigated whether activators of peroxisome proliferator-activated receptor (PPAR)alpha and PPARgamma, with their known antiinflammatory effects, might regulate the expression of proinflammatory cytokines in human CD4-positive T cells. Isolated human CD4-positive T cells express PPARalpha and PPARgamma mRNA and protein. Activation of CD4-positive T cells by anti-CD3 monoclonal antibodies significantly increased IFNgamma protein secretion from 0 to 504+/-168 pg/mL, as determined by ELISA. Pretreatment of cells with well-established PPARalpha (WY14643 or fenofibrate) or PPARgamma (BRL49653/rosiglitazone or pioglitazone) activators reduced anti-CD3-induced IFNgamma secretion in a concentration-dependent manner. PPAR activators also inhibited TNFalpha and interleukin-2 protein expression. In addition, PPAR activators markedly reduced cytokine mRNA expression in these cells. Such antiinflammatory actions were also evident in cell-cell interactions with medium conditioned by PPAR activator-treated T cells attenuating human monocyte CD64 expression and human endothelial cell major histocompatibility complex class II induction. Thus, activation of PPARalpha and PPARgamma in human CD4-positive T cells limits the expression of proinflammatory cytokines, such as IFNgamma, yielding potential therapeutic benefits in pathological processes, such as atherosclerosis and Tx-AA.