Complement escape of human pathogenic bacteria by acquisition of complement regulators

Pathogenic micro-organisms employ a broad range of strategies to survive in and to persistently infect the human host. Far from being completely understood by which highly sophisticated means invading pathogens overcome the host's destructive immune defence, there is a growing body of evidence on particular mechanisms which play a pivotal role for immune evasion. This review focuses on evasion of medically and scientifically important bacteria by acquisition of host derived fluid-phase complement regulatory proteins, in particular factor H, FHL-1, and C4b binding protein. Expression of microbial surface molecules binding to human complement regulators and thus fixing them in a functionally active state allows pathogens to inhibit and finely regulate complement activation directly on their surface. Further studies on the utilization of host complement regulatory proteins will likely have a marked impact on a more efficient and specific clinical treatment.     

Culture-independent molecular subtyping of Mycoplasma pneumoniae in clinical samples

A new molecular subtyping approach was developed which is based on the amplification and sequencing of a repetitive region of the P1 gene of Mycoplasma pneumoniae. It allows the differentiation of all known subtypes and variants of M. pneumoniae as well as the identification of new subtypes directly in clinical samples to characterize endemic and epidemic M. pneumoniae infections.     

Diagnosis of mixed Plasmodium malariae and P. vivax infection in a development aid volunteer by examination of bone-marrow specimens by real-time PCR

Mixed Plasmodium malariae and P. vivax infections in humans are reported very infrequently. The case of a 27-year-old male who sustained malaria quartana/tertiana caused by an unbalanced mixed P. malariae-P. vivax infection is reported here. Conventional tests and serology for malarial parasites were uniformly negative. Identification and quantification of the parasites were accomplished by examining bone-marrow specimens using specific real-time TaqMan PCR.     

Prospects for clinical application of electronic-nose technology to early detection of Mycobacterium tuberculosis in culture and sputum

Ziehl-Neelsen (ZN) staining for the diagnosis of tuberculosis (TB) is time-consuming and operator dependent and lacks sensitivity. A new method is urgently needed. We investigated the potential of an electronic nose (EN) (gas sensor array) comprising 14 conducting polymers to detect different Mycobacterium spp. and Pseudomonas aeruginosa in the headspaces of cultures, spiked sputa, and sputum samples from 330 culture-proven and human immunodeficiency virus-tested TB and non-TB patients. The data were analyzed using principal-component analysis, discriminant function analysis, and artificial neural networks. The EN differentiated between different Mycobacterium spp. and between mycobacteria and other lung pathogens both in culture and in spiked sputum samples. The detection limit in culture and spiked sputa was found to be 1 x 10(4) mycobacteria ml(-1). After training of the neural network with 196 sputum samples, 134 samples (55 M. tuberculosis culture-positive samples and 79 culture-negative samples) were used to challenge the model. The EN correctly predicted 89% of culture-positive patients; the six false negatives were the four ZN-negative and two ZN-positive patients. The specificity and sensitivity of the described method were 91% and 89%, respectively, compared to culture. At present, the reasons for the false negatives and false positives are unknown, but they could well be due to the nonoptimized system used here. This study has shown the ability of an electronic nose to detect M. tuberculosis in clinical specimens and opens the way to making this method a rapid and automated system for the early diagnosis of respiratory infections.     

Reconstitution of paired T cell receptor alpha- and beta-chains from microdissected single cells of human inflammatory tissues

We describe a strategy to "revive" putatively pathogenic T cells from frozen specimens of human inflammatory target organs. To distinguish pathogenic from irrelevant bystander T cells, we focused on cells that were (i) clonally expanded and (ii) in direct morphological contact with a target cell. Using CDR3 spectratyping, we identified clonally expanded T cell receptor (TCR) beta-chains in muscle sections of patients with inflammatory muscle diseases. By immunohistochemistry, we identified those Vbeta-positive T cells that fulfilled the morphological criteria of myocytotoxicity and isolated them by laser microdissection. Next, we identified coexpressed pairs of TCR alpha- and beta-chains by a multiplex PCR protocol, which allows the concomitant amplification of both chains from single cells. This concomitant amplification had not been achieved previously in histological sections, mainly because of the paucity of available anti-alpha-chain antibodies and the great heterogeneity of the alpha-chain genes. From muscle tissue of a patient with polymyositis, we isolated 64 T cells that expressed an expanded Vbeta1 chain. In 23 of these cells, we identified the corresponding alpha-chain. Twenty of these 23 alpha-chains were identical, suggesting antigen-driven selection. After functional reconstitution of the alphabeta-pairs, their antigen-recognition properties could be studied. Our results open avenues for combined analysis of the full TCR alpha- and beta-chain repertoire in human inflammatory tissues.     

von Willebrand factor-cleaving protease (ADAMTS13) in the course of stem cell transplantation

Transplantation-associated microangiopathy (TAM) is a severe complication of stem cell transplantation. Although TAM shares many features with idiopathic thrombotic thrombocytopenic purpura or hemolytic uremic syndrome, the prognosis of TAM is worse. Clinical similarities and the observation that uncleaved ultralarge von Willebrand factor (ULVWF) multimers are found in the circulation of patients suffering from TAM suggest a defect in VWF proteolysis that may be due to a deficiency in ADAMTS13 activity. In this study the course of 28 consecutive patients, who received an allogeneic stem cell transplant was correlated to ADAMTS13 activity. Before stem cell transplantation, mean ADAMTS13 activity was within normal range. Within the first 8 weeks, mean activity declined to less than half the baseline activity. Furthermore, most of the patients showed normalization of ADAMTS13 activity. Low levels of ADAMTS13 activity were not correlated with clinical signs of thrombotic microangiopathy. However, two patients with clinical TAM had the lowest activity of all patients when suffering a severe bout of microangiopathy. Plasma exchange was not able to normalize ADAMTS13 deficiency in these patients, suggesting inactivation or consumption of ADAMTS13 activity in TAM.     

Small peripheral developing odontoma of the maxilla in a 3-year-old patient depicted on cone-beam tomograms

A 3-year-old male patient was referred to the Maxillofacial Surgery Clinic due to a painless swelling of the right palatal region. Conventional radiographs revealed no alteration of the dentition and did not delineate a lesion in the region of interest. Cone-beam tomography depicted small radiopaque, extraosseous deposits inside the palatal space. Histological examination revealed a minute mixed epithelial-mesenchymal lesion of odontogenic origin. We made the diagnosis of a peripheral developing odontoma, taking into consideration the components and arrangements of structures of the lesion. Early intervention is advisable to prevent these odontogenic lesions from eventually deforming the jaw and displacing adjacent teeth. Cone-beam tomography was a valuable pre-operative diagnostic tool to assess the lesion as being composed in part of hard tissue.     

Effect of visual restitution training on absolute homonymous scotomas

The authors examined 16 patients with stable homonymous visual field defects (HVFDs) with static automated perimetry (SAP). Training effect E was defined as difference of the proportions of absolutely defective locations in all test locations, before and after visual restitution training (VRT). E was 0.05 +/- 0.05 (mean +/- SD). The authors observed a relevant training effect (E >or= 0.12) in two subjects, but only monocularly. VRT has little effect on absolute HVFDs in SAP.