Multi-qubit entanglement and algorithms on a neutral-atom quantum computer.

Gate-model quantum computers promise to solve currently intractable computational problems if they can be operated at scale with long coherence times and high-fidelity logic. Neutral-atom hyperfine qubits provide inherent scalability owing to their identical characteristics, long coherence times and ability to be trapped in dense, multidimensional arrays1. Combined with the strong entangling interactions provided by Rydberg states2-4, all the necessary characteristics for quantum computation are available. Here we demonstrate several quantum algorithms on a programmable gate-model neutral-atom quantum computer in an architecture based on individual addressing of single atoms with tightly focused optical beams scanned across a two-dimensional array of qubits. Preparation of entangled Greenberger-Horne-Zeilinger (GHZ) states5 with up to six qubits, quantum phase estimation for a chemistry problem6 and the quantum approximate optimization algorithm (QAOA)7 for the maximum cut (MaxCut) graph problem are demonstrated. These results highlight the emergent capability of neutral-atom qubit arrays for universal, programmable quantum computation, as well as preparation of non-classical states of use for quantum-enhanced sensing.

Validation of Mycobacterium tuberculosis dihydroneopterin aldolase as a molecular target for anti-tuberculosis drug development.

An early step of target validation in antimicrobial drug discovery is to prove that a gene coding for a putative target is essential for pathogen's viability. However, little attention has been paid to demonstrate the causal links between gene essentiality and a particular protein function that will be the focus of a drug discovery effort. This should be considered an important step in target validation since a growing number of proteins are found to exhibit multiple and unrelated tasks. Here, we show that the Mycobacterium tuberculosis (Mtb) folB gene is essential and that this essentiality depends on the dihydroneopterin aldolase/epimerase activities of its protein product, the FolB protein from the folate biosynthesis pathway. The wild-type (WT) MtFolB and point mutants K99A and Y54F were cloned, expressed, purified and monitored for the aldolase, epimerase and oxygenase activities using HPLC. In contrast to the WT MtFolB, both mutants have neither aldolase nor epimerase activities in the conditions assayed. We then performed gene knockout experiments and showed that folB gene is essential for Mtb survival under the conditions tested. Moreover, only the WT folB sequence could be used as a rescue copy in gene complementation studies. When the sequences of mutants K99A or Y54F were used for complementation, no viable colonies were obtained, indicating that aldolase and/or epimerase activities are crucial for Mtb survival. These results provide a solid basis for further work aiming to develop new anti-TB agents acting as inhibitors of the aldolase/epimerase activities of MtFolB.

Heparin-induced thrombocytopenia: a prospective study on the incidence, platelet-activating capacity and clinical significance of antiplatelet factor 4/heparin antibodies of the IgG, IgM, and IgA classes.

INTRODUCTION: Platelet-activating antiplatelet factor 4/heparin (anti-PF4/heparin) antibodies are the major cause of heparin-induced thrombocytopenia (HIT). However, the relative utility of functional (platelet activation) vs. antigen [enzyme-immunoassay (EIA)] assays, and the significance of assay discrepancies remain unresolved. METHODS: Consecutive patient sera (n = 1650) referred for diagnostic HIT testing were screened prospectively by both the heparin-induced platelet activation (HIPA) test and anti-PF4/heparin EIA - including individual classes (IgG, IgA, IgM) - with clinical correlations studied. Platelet microparticle and annexin-V-binding properties of the sera were also investigated. RESULTS: Only 205 (12.4%) sera tested positive in either the HIPA and/or EIA: 95 (46.3%) were positive in both, 109 (53.1%) were only EIA-positive, and, notably, only one serum was HIPA-positive/EIA-negative. Of 185 EIA-positive sera, only 17.6% had detectable IgM and/or IgA without detectable IgG. Among sera positive for EIA IgG, optical density values were higher when the sera were HIPA-positive (1.117 vs. 0.768; P < 0.0001), with widely overlapping values. Two HIPA-positive but EIA-IgG-negative sera became HIPA-negative following IgG depletion, suggesting platelet-activating antibodies against non-PF4-dependent antigens. Clinical correlations showed that HIPA-negative/EIA-positive patients did not develop thrombosis and had reasons other than HIT to explain thrombocytopenia. IgM/A antibodies did not increase microparticle penetration, but increased annexin-V binding. CONCLUSIONS: The anti-PF4/heparin EIA has high ( approximately 99%) sensitivity for HIT. However, only about half of EIA-positive patients are likely to have HIT. Anti-PF4/heparin antibodies of IgM/A class and non-PF4-dependent antigens have only a minor role in HIT.

IgG classification of anti-PF4/heparin antibodies to identify patients with heparin-induced thrombocytopenia during mechanical circulatory support.

Commercial immunoassays frequently detect anti-PF4/heparin antibodies during mechanical circulatory support (MCS), but only a small minority of patients develops heparin-induced thrombocytopenia (HIT). Whereas platelet functional tests can distinguish between platelet-activating and non-platelet-activating antibodies, commercial PF4-dependent immunoassays do not. Between 2003 and 2004, 113 patients were placed on MCS. Blood samples were obtained on postimplant day 5-7 for analyses by antibody assays and the functional heparin-induced platelet activation (HIPA) assay. Three distinct groups of patient sera were identified: platelet-activating anti-PF4/heparin antibodies (n = 10), non-platelet-activating anti-PF4/heparin antibodies (n = 53), and anti-PF4/heparin antibody negative (n = 50). Patients with platelet-activating antibodies had the highest risk for thromboembolic events (P < 0.005), whereas those with non-platelet-activating antibodies did not differ from antibody negative patients (P = 0.369). The enzyme-immunoassay and column agglutination assays, which cover all immunoglobulin classes, demonstrated adequate sensitivity and negative predictive value; yet, both lacked specificity with respect to the platelet-activating antibodies. If all antibody positive patients were further classified by an IgG-specific anti-PF4/heparin enzyme-immuno assay, specificity for platelet-activating antibodies increased. Whereas IgG-specific optical density (OD) values below 1.0 were likely for non-platelet-activating anti-PF4/heparin antibodies, higher values were progressively predictive for pathogenic platelet activation. The probability of the development of clinical HIT also increased steeply. In conclusion, platelet-activating anti-PF4/heparin antibodies are relatively common (about 9%) in patients on MCS and are associated with significantly higher thrombotic event rates. Low IgG-specific OD values (< 1.0) in the enzyme-immunoassay indicate low likelihood for the presence of platelet-activating antibodies. These results justify further validation so that anticoagulation during MCS becomes safer and adequate.

Evaluation of pretest clinical score (4 T's) for the diagnosis of heparin-induced thrombocytopenia in two clinical settings.

BACKGROUND: Heparin-induced thrombocytopenia (HIT) is a prothrombotic adverse drug reaction caused by heparin. As thrombocytopenia is common in hospitalized patients receiving heparin, it would be useful to have a clinical scoring system that could differentiate patients with HIT from those with other reasons for thrombocytopenia. AIM: To compare prospectively the diagnostic utility of a clinical score for HIT in two different clinical settings. METHODS: The pretest clinical scoring system, the '4 T's', was used to classify 100 consecutive patients referred for possible HIT in one hospital (Hamilton General Hospital, HGH) into high, intermediate, and low probability groups. This system was also used to classify likewise 236 patients by clinicians in Germany referring blood for diagnostic testing for HIT in Greifswald (GW). The clinical scores were correlated with the results of laboratory testing for HIT antibodies using the serologic criteria for HIT with high diagnostic specificity. RESULTS: In both centers, patients with low scores were unlikely to test positive for HIT antibodies [HGH: 1/64 (1.6%), GW: 0/55 (0%)]. Patients with intermediate [HGH: 8/28 (28.6%), GW: 11/139 (7.9%)] or high scores [HGH: 8/8 (100%), GW: 9/42 (21.4%)] were more likely to test positive for clinically significant HIT antibodies. The positive predictive value of an intermediate or high clinical score for clinically significant HIT antibodies was higher at one center (HGH). CONCLUSIONS: A low pretest clinical score for HIT seems to be suitable for ruling out HIT in most situations (high-negative predictive value). The implications of an intermediate or high score vary in different clinical settings.

Avoiding misclassification bias with the traditional Charnley classification: rationale for a fourth Charnley class BB.

Long-term follow up of patients with total hip arthroplasty (THA) revealed a marked deterioration of walking capacities in Charnley class B after postoperative year 4. We hypothesized that a specific group of patients, namely those with unilateral hip arthroplasty and an untreated but affected contralateral hip was responsible for this observation. Therefore, we conducted a study taking into consideration the two subclasses that make up Charnley class B: patients with unilateral THA and contralateral hip disease and patients with bilateral THA. A sample of 15,160 patients with 35,773 follow ups that were prospectively collected over 10 years was evaluated. The sample was categorized into four classes according to a new modified Charnley classification. Annual analyses of the proportion of patients with ambulation longer than 60 min were conducted. The traditionally labeled Charnley class B consists of two very different patient groups with respect to their walking capacities. Those with unilateral THA and contralateral hip disease have underaverage walking capacities and a deterioration of ambulation beginning 3 to 4 years after surgery. Those with bilateral THA have stable overaverage walking capacities similar to Charnley class A. An extension of the traditional Charnley classification is proposed, taking into account the two different patient groups in Charnley class B. The new fourth Charnley class consists of patients with bilateral THA and was labeled BB in order to express the presence of two artificial hip joints and to preserve the traditional classification A through C.

Anaphylactic and anaphylactoid reactions associated with lepirudin in patients with heparin-induced thrombocytopenia.

BACKGROUND: Lepirudin (Refludan) is a hirudin derivative. It is a direct thrombin inhibitor obtained by recombinant technology from the medicinal leech and is approved for treatment of heparin-induced thrombocytopenia complicated by thrombosis. Because 3 cases of fatal anaphylaxis possibly associated with use of lepirudin have been reported, we initiated an investigation of putative lepirudin-associated anaphylaxis. METHODS AND RESULTS: Aided by the manufacturer (Schering AG, Berlin, Germany), we used the lepirudin study databases to identify all patients in whom possible anaphylaxis/severe allergy was recorded from 1994 to September 2002. The 26 possible cases identified were reviewed independently by 2 investigators. After excluding patients with mild skin reactions, reactions likely caused by concomitant medications, poorly documented cases, and reactions that did not correspond temporally with lepirudin use, there remained 9 patients judged to have had severe anaphylaxis in close temporal association with lepirudin. All reactions occurred within minutes of intravenous lepirudin administration, with 4 fatal outcomes (3 acute cardiorespiratory arrests, 1 hypotension-induced myocardial infarction). In these 4 cases, a previous uneventful treatment course with lepirudin was identified (1 to 12 weeks earlier). We recorded high-titer IgG-anti-lepirudin antibodies in an additional patient with anaphylaxis. Because lepirudin has been used in approximately 35 000 patients, the risk of anaphylaxis is approximately 0.015% (5 of 32 500) on first exposure and 0.16% (4 of 2500) in reexposed patients (7.5% estimated reexposures). CONCLUSIONS: Lepirudin can cause fatal anaphylaxis, particularly in patients who are treated within 3 months of a previous exposure. The overall risk/benefit assessment of lepirudin as a treatment for heparin-induced thrombocytopenia remains favorable.

Lepirudin (recombinant hirudin) for parenteral anticoagulation in patients with heparin-induced thrombocytopenia. Heparin-Associated Thrombocytopenia Study (HAT) investigators.

BACKGROUND: We prospectively investigated lepirudin for further parenteral anticoagulation in patients with heparin-induced thrombocytopenia (HIT). METHODS AND RESULTS: Patients with confirmed HIT (n=112) received lepirudin according to need for 2 to 10 days (longer if necessary): A1, treatment: 0.4 mg/kg IV bolus, followed by 0.15 mg. kg(-1). h(-1) intravenous infusion, n=65; A2, treatment in conjunction with thrombolysis: 0.2 mg/kg, followed by 0.10 mg. kg(-1). h(-1), n=4; and B, prophylaxis: 0.10 mg. kg(-1). h(-1), n=43. Outcomes from 95 eligible lepirudin-treated patients were compared with those of historical control patients (n=120). Complete laboratory response (activated partial thromboplastin time ratio >1.5 with /=1 outcome (cumulative incidence 30.9% versus 52.1%; relative risk [RR] 0.71; P=0.12, log-rank test). Bleeding events were more frequent in the lepirudin group than the historical control group (cumulative incidence at 35 days, 44.6% versus 27.2%; RR 2.57; P=0.0001, log-rank test). No difference was observed in bleeding events requiring transfusion (cumulative incidence at 35 days, 12.9% versus 9.1%; RR 1.66; P=0.23, log-rank test); no intracranial bleeding was observed in the lepirudin group. CONCLUSIONS: Lepirudin effectively prevents death, limb amputations, and new thromboembolic complications and has an acceptable safety profile in HIT patients. Treatment should be initiated as soon as possible if HIT is suspected.

Lepirudin in patients with heparin-induced thrombocytopenia - results of the third prospective study (HAT-3) and a combined analysis of HAT-1, HAT-2, and HAT-3.

OBJECTIVES: To assess efficacy and safety of lepirudin in patients with heparin-induced thrombocytopenia (HIT) in a prospective study (HAT-3) as well as in a combined analysis of all HAT study data. PATIENTS/METHODS: Patients with laboratory-confirmed HIT were treated with lepirudin in three different aPTT-adjusted dose regimen and during cardiopulmonary bypass (CPB). Endpoints were new thromboembolic complications (TEC), limb amputations, and death and major bleeding. A historical control group (n = 120) was used for comparison. RESULTS: After start of lepirudin in 205 patients treated in HAT-3, the combined endpoint occurred in 43 (21.0%). Thirty (14.6%) patients died, 10 (4.9%) underwent limb amputation, and 11 (5.4%) new TECs occurred. Major bleeding occurred in 40 patients (19.5%) (seven during CPB surgery). Combining all prospective HAT trials (n = 403), after start of lepirudin treatment, the combined endpoint occurred in 82 patients (20.3%), with 47 deaths (11.7%), 22 limb amputations (5.5%), 30 new TECs (7.4%), and 71 (17.6%) major bleedings. Compared with the historical control group (log-rank test), the combined endpoint after start of treatment was reduced (29.7% vs. 52.1%, P = 0.0473), primarily because of reduction in new thromboses (11.9% vs. 32.1%, P = 0.0008). Mean lepirudin maintenance doses ranged from 0.07 to 0.11 mg kg(-1) h(-1). Major bleeding was more frequent in the lepirudin-treated patients (29.4% vs. 9.1%, P = 0.0148). CONCLUSIONS: The rate of new TECs in HIT patients is low after start of lepirudin treatment. The rate of major bleeding of 17.6% might be reduced by reducing the starting dose to 0.1 mg kg(-1) h(-1).

A comparison of danaparoid and lepirudin in heparin-induced thrombocytopenia.

Heparin-induced thrombocytopenia (HIT) is a hypercoagulable syndrome strongly associated with thrombosis that is usually treated with drugs that inhibit factor Xa (danaparoid) or thrombin (lepirudin). In the present study the outcome of HIT-patients treated with danaparoid or lepirudin was compared using the single or combined endpoints of new thromboembolic complications (new TECs), amputations and/or death, and major bleeding. HIT-patients treated with lepirudin were enrolled in two prospective trials and patients, who were identified in the same two laboratories during the same time period, who were not enrolled into these studies but treated with danaparoid, were assessed retrospectively according to a standardized questionnaire. 126 danaparoid (60.3% female) and 175 lepirudin treated patients (58.3% female) fulfilled the same inclusion and exclusion criteria. In a time-to-event-analysis the cumulative risk of combined endpoint was higher in HIT-patients without thromboembolic complication at baseline treated with danaparoid (usually in prophylactic dose 750 anti-factor Xa units b.i.d. or t.i.d.s.c.) as compared to lepirudin (aPTT adjusted) (P = 0.020). Whereas HIT-patients with TEC at baseline who were usually treated with therapeutic dose had a similar outcome in both treatment groups (P = 0.913). Major bleeding occurred in 2.5% (95% CI 0.5-7.0%) of danaparoid treated patients as compared to 10.4% (95% CI 6.3-15.9%) of lepirudin treated patients until day 42 (P = 0.009). This indicates that the efficacies of therapeutic doses of danaparoid or lepirudin in preventing death, amputation or new TEC in HIT-patients do not differ largely, but the risk of bleeding seems to be higher in lepirudin treated patients. The prophylactic dose of danaparoid approved in the European Union for HIT without TEC at baseline seems suboptimal. A prospective comparative trial is required to verify these preliminary conclusions.

First workshop for detection of heparin-induced antibodies: validation of the heparin-induced platelet-activation test (HIPA) in comparison with a PF4/heparin ELISA.

BACKGROUND: No data exist regarding the inter-laboratory reproducibility of the heparin-induced-platelet-activation (HIPA) test, the most widely used functional assay in Germany for the detection of heparin-induced thrombocytopenia (HIT) antibodies. METHODS: Nine laboratories used an identical protocol to test eight different sera with the HIPA test. Five laboratories also tested the sera with a platelet factor 4 (PF4)/heparin-complex ELISA. Cross-reactivity with danaparoid-sodium was assessed using 0.2 aFXa units instead of heparin in the HIPA test. RESULTS: Two of nine laboratories had no discrepant HIPA test results. Four laboratories differed in one sample, one reported two discrepant results, and two laboratories reported more than two discrepant results. Cross-reactivity with danaparoid-sodium test results differed among laboratories. PF4/heparin ELISA results were identical in all five laboratories. CONCLUSION: The HIPA test requires strict quality control measures. Using both a sensitive functional assay (HIPA test) and a PF4/heparin ELISA will allow detection of antibodies directed to antigens other than PF4/heparin complexes as well as detection of IgM and IgA antibodies with PF4/heparin specificity.

Very low platelet counts in post-transfusion purpura falsely diagnosed as heparin-induced thrombocytopenia. Report of four cases and review of literature.

Differential diagnosis between post-transfusion purpura (PTP) and heparin-induced thrombocytopenia (HIT) can be difficult in the initial stages of thrombocytopenia, as the early clinical presentations are often similar. Four patients are described who were suspected clinically of suffering from HIT. All four patients had recent blood transfusions and platelet alloantibodies, thus the diagnosis of PTP was made. One lethal gastrointestinal and one retroperitoneal hemorrhage developed in two of the four patients. Unusually, one patient was male and two different platelet alloantibodies were present in his serum; in another patient platelet alloantibodies and HIT-antibodies were detectable. To arrive at the right diagnosis as quickly as possible is vitally important since treatment, which has to be initiated promptly, is very different for the two syndromes. Thus, we suggest that in patients where HIT is suspected, additional information should be sought. If features consistent with PTP (such as a recent blood transfusion or a marked drop in platelet count to below 15 Gpt/L) are present, we recommend parallel testing for platelet alloantibodies to rule out PTP.

A prospective study on the incidence and clinical relevance of heparin-induced antibodies in patients after vascular surgery.

The heparin-platelet factor 4-antibody assay, polyanion-platelet factor 4-antibody assay and heparin-induced platelet activation test are used for laboratory diagnosis of the immune form of heparin-induced thrombocytopenia. Fifty consecutive patients receiving heparin treatment for more than 5 days after vascular surgery were prospectively screened for heparin-induced thrombocytopenia antibodies, thrombocytopenia (daily platelet counts), deep-vein thrombosis (color-coded duplex sonography), and arterial reocclusion (clinical assessment). None of the patients developed thrombocytopenia or thrombosis in association with formation of heparin-induced thrombocytopenia antibodies. Despite the absence of clinical evidence of heparin-induced thrombocytopenia, many patients formed heparin-induced thrombocytopenia antibodies: 34% of the patients were positive in the heparin-platelet factor 4-antibody assay, 28% in the polyanion-platelet factor 4-antibody assay, 14% in the heparin-induced platelet activation test, and 54% with any of these tests. Patients predominantly developed IgM (24%) and IgA antibodies (16%), whereas IgG antibodies were found in 12% of patients. Whereas the majority of patients with positive ELISA assays had IgM and IgA antibodies, patients with a positive functional assay (heparin-induced platelet activation test) predominantly had IgG antibodies. We conclude that a high percentage of patients develop heparin-induced antibodies after vascular surgery without any clinical symptoms of heparin-induced thrombocytopenia. None of the assays therefore is predictive of the clinical manifestation of heparin-induced thrombocytopenia in asymptomatic patients. Therefore, the diagnostic specificity of both antigen and activation assays for heparin-induced thrombocytopenia appears to be relatively low in the vascular surgery patient population.

Drug-induced and drug-dependent immune thrombocytopenias.

Thrombocytopenia is a frequent comorbid condition in many in hospital patients. In some patients, drugs are the cause of low platelet counts. While cytotoxic effects of anti-tumor therapy are the most frequent cause, immune mechanisms should also be considered. This review addresses thrombocytopenias in four groups. Heparin-dependent thrombocytopenia (HIT), by far the most frequent drug-induced immune-mediated type of thrombocytopenia, has a unique pathogenesis and clinical consequences. HIT is a clinicopathological syndrome in which antibodies mostly directed against a multimolecular complex of platelet factor 4 and heparin cause paradoxical thromboembolic complications. The mechanisms through which heparin can enhance thrombin generation are discussed and treatment alternatives for affected patients are presented in detail. It is of primary importance to recognize these patients as early as possible and to substitute heparin with a compatible anticoagulatory drug, such as hirudin, danaparoid or argatroban. Patients seem to benefit from therapeutic doses of alternative treatment rather than from low-dose prophylactic doses. With the increasing use of glycoprotein (GP) IIb/IIIa inhibitors in patients with acute coronary syndromes, thrombocytopenias are increasingly recognized as an adverse effect of these drugs. Up to 4% of treated patients are affected. Most important, pseudothrombocytopenia, a laboratory artefact, is as frequent as real drug-induced thrombocytopenia and must be excluded before changes in treatment are considered. The pathogenesis of these thrombocytopenias is still debated; an immune mechanism involving preformed antibodies is likely. However, since these antibodies are also detectable in a high percentage of normal controls and of patients not developing thrombocytopenia, their impact is still unclear. Patients with real thrombocytopenia are at an increased risk of bleeding; treatment consists of cessation of the GP IIb/IIIa inhibitor and platelet transfusions in cases of severe hemorrhage. Classic immune thrombocytopenia can be induced by some drugs, e.g. gold, which trigger anti-platelet antibodies indistinguishable from platelet autoantibodies found in autoimmune thrombocytopenia. Drug-induced and drug-dependent immune thrombocytopenia is induced by antibodies recognizing an epitope on platelet GP formed after binding of a drug to a platelet glycoprotein. Still unresolved is whether antibody binding is the consequence of a conformational change of the antigen, the antibody, or both. These antibodies typically react with monomorphic epitopes on platelet GP, but only in the presence of the drug or a metabolite. Although several platelet GP have been identified as antibody target (GPIb/IX, GPV, GP IIb/IIIa), antibodies in an individual patient are highly specific for a single GP. Clinically, these patients present with very low platelet counts and acute, sometimes severe, hemorrhage. Treatment is restricted to withdrawal of the drug and symptomatic treatment of bleeding.

Atypical heparin-induced thrombocytopenia complicated by intracardiac thrombus, effectively treated with ultra-low-dose rt-PA lysis and recombinant hirudin (Lepirudin).

A serious retroperitoneal bleeding occurred in a 56-year-old male patient receiving unfractionated heparin due to multiple pulmonary embolism. After reducing the heparin dose, the patient developed a new pulmonary embolism and a large thrombus in the right atrium. Concomitantly, the platelet count dropped to a value of 29 g/l. Heparin-induced thrombocytopenia (HIT) was confirmed by a functional assay, the heparin-induced platelet activation (HIPA) assay, whereas the results of a platelet factor 4/heparin complex ELISA were repeatedly negative. This indicated that the patient's HIT antibodies were directed towards an antigen other than platelet factor 4/heparin complexes. For treatment of the atrial thrombus, an ultra-low-dose lysis with rt-PA (2 mg/h, intravenously) was administered for a period of 52 h, overlapping with systemic treatment with recombinant hirudin (Lepirudin, Refludan, 0.06-0.14 mg/kg/h intravenously). The aim was to enhance lysis of the thrombus without increasing the haematoma, and at the same time keep the risk of fulminant pulmonary embolism due to thrombus fragmentation as low as possible. The cardiac thrombus disappeared within 48 h, without new signs of pulmonary embolism. Platelet counts normalized within nine days.

[Difficulties of fungus detection in corneal culture medium]. / Schwierigkeiten beim Pilznachweis in Hornhautkulturmedium.

UNLABELLED: It is not always possible to prevent the growth of microorganisms in organ culture for cornea preservation, despite many prophylactic measures. It is especially difficult to prove the presence of fungi in the cultural medium. MATERIALS AND METHODS: A culture medium was examined for sterility after 8 days' storage of cornea in organ culture. To prove the presence of fungi a culture of Sabouraud 2% glucose-agar was prepared and its growth examined by light microscopy. RESULTS: After 8 days of preservation we noticed a color change in the cultural medium and suspected contamination with fungi. Coagulase-negative Staphylococci could be cultivated from the conjunctival smear obtained before preparation of the cornea only. Routine screening of microbiological contamination did not show any results. We were able to identify an Aspergillus species only after preparing a special culture. The conjunctival smear as well as the cultural medium of the other eye of the same donor showed no contamination. CONCLUSIONS: In spite of the fact that microbiological contamination can be seen macroscopically, it is difficult to prove the presence of a specific microorganism and even more so when dealing with fungus. Especially in these cases the incubation of the cornea in media might have an advantage because contamination can be suspected by just looking at the medium. By excluding these preparations from transplantation we can possibly prevent infections, even when routine examinations show negative results.

Tracing latitudinal gradient, river discharge and water masses along the subtropical South American coast using benthic Foraminifera assemblages.

More than 30% of Buccella peruviana (D'Orbigny), Globocassidulina crassa porrecta (Earland & Heron-Allen), Cibicides mackannai (Galloway & Wissler) and C. refulgens (Montfort) indicate the presence of cold Sub Antarctic Shelf Water in winter, from 33.5 to 38.3º S, deeper than 100 m, in the southern part of the study area. In summer, the abundance of this association decreases to less than 15% around 37.5-38.9º S where two species (Globocassidulina subglobosa (Brady), Uvigerina peregrina (Cushman) take over. G. subglobosa, U. peregrina, and Hanzawaia boueana (D'Orbigny) are found at 27-33º S in both seasons in less than 55 m deep in the northern part, and are linked with warm Subtropical Shelf Water and Tropical Water. Freshwater influence was signalized by high silicate concentration and by the presence of Pseudononion atlanticum (Cushman), Bolivina striatula (Cushman), Buliminella elegantissima (D'Orbigny), Bulimina elongata (D'Orbigny), Elphidium excavatum (Terquem), E. poeyanum (D'Orbigny), Ammobaculites exiguus (Cushman & Brönnimann), Arenoparrella mexicana (Kornfeld), Gaudryina exillis (Cushman & Brönnimann), Textularia earlandi (Parker) and thecamoebians in four sectors of the shelf. The presence of Bulimina marginata (D'Orbigny) between 34.1-32.8º S in the winter and 34.2-32.7º S in the summer indicates that the influence of the Subtropical Shelf Front on the sediment does not change seasonally, otherwise, the presence of Angulogerina angulosa (Williamson) in the winter, only in Mar del Plata (38.9º S), show that Malvinas currents are not influencing the sediment in the summer.

Clonal distribution of superantigen genes in clinical Staphylococcus aureus isolates.

Staphylococcus aureus is both a successful human commensal and a major pathogen. The elucidation of the molecular determinants of virulence, in particular assessment of the contributions of the genetic background versus those of mobile genetic elements (MGEs), has proved difficult in this variable species. To address this, we simultaneously determined the genetic backgrounds (spa typing) and the distributions of all 19 known superantigens and the exfoliative toxins A and D (multiplex PCR) as markers for MGEs. Methicillin- sensitive S. aureus strains from Pomerania, 107 nasal and 88 blood culture isolates, were investigated. All superantigen-encoding MGEs were linked more or less tightly to the genetic background. Thus, each S. aureus clonal complex was characterized by a typical repertoire of superantigen and exfoliative toxin genes. However, within each S. aureus clonal complex and even within the same spa type, virulence gene profiles varied remarkably. Therefore, virulence genes of nasal and blood culture isolates were separately compared in each clonal complex. The results indicated a role in infection for the MGE harboring the exfoliative toxin D gene. In contrast, there was no association of superantigen genes with bloodstream invasion. In summary, we show here that the simultaneous assessment of virulence gene profiles and the genetic background increases the discriminatory power of genetic investigations into the mechanisms of S. aureus pathogenesis.

Post-transfusion purpura in a patient with HPA-1a and GPIa/IIa antibodies.

Post-transfusion purpura is a rare bleeding disorder characterized by severe and sudden thrombocytopenia within 3-12 days after blood transfusion. Typically, preformed antibodies directed against human platelet antigens, especially HPA-1a, are associated with the clinical symptoms. A 46-year-old female presenting to the hospital with acute progressive kidney insufficiency and anaemia received two units of packed red blood cells (RBC) within 2 days. On day 7, platelet count felt from 414 to 189 x 10(9) L(-1) and 1 day later dropped to 4 x 10(9) L(-1). Four platelet concentrates were applied without success. After serological confirmation of an HPA-1a antibody, the patient was treated with intravenous gamma immunoglobulin (ivIgG), and the platelet count increased to normal values on day 17. In addition to the persisting HPA-1a alloantibody, an antibody reactive with GPIa/IIa of HPA-5a- and HPA-5b-positive platelets was detected during the acute phase of thrombocytopenia. After complete remission, the patient was transfused with four units of packed RBC from HPA-1a-negative donors, and platelet counts remained normal.