Interpretation of low-level Plasmodium infection rates determined by ELISA for anophelines (Diptera: Culicidae) from Egyptian oases

Plasmodium infection rates determined by enzyme-linked immunosorbent assay (ELISA) were compared for Anopheles sergentii (Theobald) and An. multicolor Cambouliu in Siwa Oasis, Egypt, an area with low-level Plasmodium vivax transmission, and in Bahariya and Farafra, two other Egyptian oases which appear to be free of malaria. Initial testing indicated that 4.4% (23 of 518) and 0.8% (4 of 518) of the An. sergentii were positive for P. vivax and P. falciparum, respectively, and that 1.4% (1 of 71) of the An. multicolor were positive for P. falciparum. However, after two confirmational tests, only 1.2% (6 of 518) of the An. sergentii remained consistently positive for P. vivax. Initial ELISA absorbance was not a useful predictor of potential false positive reactions in the P. vivax assay. Paradoxically, the six ELISA-positive An. sergentii were from the two malaria-free oases. This study raises the question of whether ELISA-positive reactions for anopheline vector species provides unequivocal evidence for transmission in areas of low malaria endemicity.     

Elevated serum endostatin levels is associated with favorable outcome in acute myeloid leukemia

Introduction

Endostatin is the C-terminal antiangiogenic fragment of the extracellular matrix protein collagen XVIII, and is generated by tumor-derived proteases. The levels and the prognostic relevance of serum endostatin in AML patient is not fully clear.

Aim

To evaluate serum levels of endostatin in acute myeloid leukemia patients before chemotherapy and after achieving complete remission and to correlate endostatin levels with patients outcome.

Materials and methods

Serum samples from 30 adult patients (22 males and 8 females, median age 37, range 19–66 years) with AML had been taken before chemotherapy was administered. In addition 20 out of 30 patients were reinvestigated again at complete remission (CR). Ten samples from healthy normal persons of matched age and sex were evaluated as a reference control group. Serum endostatin levels were determined using enzyme linked immune sorbent assay (ELISA).

Results

Endostatin serum levels were not significantly different in the pretreatment AML patients as compared to that in normal controls (P>0.05). In AML patients the baseline endostatin levels were significantly lower than at CR (P=0.001). No significant correlation were detected between pretreatment serum endostatin levels and age, peripheral blood white cell counts, platelet counts, bone marrow blast cell counts, blast cell distribution ratio. The prognostic value of sE was also evaluated by dividing AML patients into high and low sE groups using the 75 percentile sE levels of the patients group as cutoff. The authors found that patients group in the high sE group survived for significantly longer time than those patients in the low sE group.

Conclusions

Elevated endostatin levels at AML diagnosis is a good prognostic marker for patients’ outcome. Wide scale study is recommended in order to establish the clinical value of this study.

     

Minimally invasive tricuspid valve surgery

Tricuspid valve disease carries a very unfavorable prognosis when medically treated. Despite that, surgical intervention is still underperformed for tricuspid valve disease due to the reported high morbidity and mortality from a sternotomy approach. This had led to a shift towards maximizing medical therapy for right ventricular failure and, as a result, a more significant delay in surgical referrals with surgical risks when patients are finally referred. Tricuspid valve patients usually have other co-morbidities resulting from their systemic venous congestion and low flow cardiac output. Minimally invasive tricuspid valve surgery provides less tissue injury and, as a result, less trauma during surgery. This provides a hope for both patients and treating doctors to be more open for providing this procedure with less complications. Isolated minimally invasive tricuspid valve surgery is still not performed as widely as expected. This can be partly due to the adverse outcomes historically labelled to tricuspid valve surgery or by the long journey of learning the surgical team would need to commit to with a minimal access approach. In this article we will review the perioperative pathway, and outcomes of isolated minimally invasive tricuspid valve surgery in the available English literature.     

Low-dose recombinant properdin provides substantial protection against Streptococcus pneumoniae and Neisseria meningitidis infection

Modern medicine has established three central antimicrobial therapeutic concepts: vaccination, antibiotics, and, recently, the use of active immunotherapy to enhance the immune response toward specific pathogens. The efficacy of vaccination and antibiotics is limited by the emergence of new pathogen strains and the increased incidence of antibiotic resistance. To date, immunotherapy development has focused mainly on cytokines. Here we report the successful therapeutic application of a complement component, a recombinant form of properdin (P_n), with significantly higher activity than native properdin, which promotes complement activation via the alternative pathway, affording protection against N. menigitidis and S. pneumoniae. In a mouse model of infection, we challenged C57BL/6 WT mice with N. menigitidis B-MC58 6 h after i.p. administration of P_n (100 µg/mouse) or buffer alone. Twelve hours later, all control mice showed clear symptoms of infectious disease while the P_n treated group looked healthy. After 16 hours, all control mice developed sepsis and had to be culled, while only 10% of P_n treated mice presented with sepsis and recoverable levels of live Meningococci. In a parallel experiment, mice were challenged intranasally with a lethal dose of S. pneumoniae D39. Mice that received a single i.p. dose of P_n at the time of infection showed no signs of bacteremia at 12 h postinfection and had prolonged survival times compared with the saline-treated control group (P < 0.0001). Our findings show a significant therapeutic benefit of P_n administration and suggest that its antimicrobial activity could open new avenues for fighting infections caused by multidrug-resistant neisserial or streptococcal strains.Pneumococcal and meningococcal infectious diseases remain a serious threat to public health. Streptococcus pneumoniae is the leading cause of community-acquired pneumonia and a major cause of otitis media, septicemia, and meningitis (1, 2). S. pneumoniae is responsible for ∼1.2 million deaths per year worldwide, with young children and immunocompromised patients at particular risk (3). Neisseria meningitidis causes epidemic bacterial meningitis and septicemia, with high mortality in children and young adults (4). The impact of meningococcal disease on human health is defined by both the risk and the severity of invasive meningococcal infections, with unacceptably high mortality rates, ranging from 10% in patients under optimal clinical therapy with the latest generation of antibiotics to up to 40% in patients with untreated septicemia. Almost one-third of those who survive invasive infections are left with long-term disabilities and long-term morbidity. Globally, the World Health Organization estimates that ∼1.2 million cases of invasive meningococcal infections occur annually, leading to more than 135,000 fatalities (5).Vaccination programs have reduced the rates of infection in developed countries, but neonates and elderly adults remain especially vulnerable (6, 7). The efficacy of vaccination is further limited by the emergence of new strains of S. pneumoniae and N. meningitidis.The complement system plays a major role in the host resistance to both pathogens (8–13). Complement is activated via three routes: the classical pathway, the lectin pathway, and the alternative pathway. Activation of the classical and lectin pathways is mediated by specific recognition molecules. Binding of C1q to the bacterial surface or the Fc region of antibody initiates the classical pathway. The lectin pathway is initiated by carbohydrate recognition molecules, including mannan-binding lectin, ficolins, and collectin 11, which bind directly to bacterial polysaccharides. Activation of the classical or lectin pathway leads to the formation of a C3 convertase (C4b2a), which splits C3 into the biologically active fragments, C3b and C3a. C3b can bind covalently to an activating surface, and hundreds of molecules of C3b can be deposited in close proximity to the C3 convertase complex. Accumulation of C3b close to C4b2a forms the classical pathway C5 convertase C4b2a(3b)_n, in which C4b and C3b form a binding site for C5, orienting it for cleavage by C2a (14, 15).The mechanisms initiating the alternative pathway are less well understood. It is widely accepted that the alternative pathway maintains a continuous state of low-rate activation, which is held in check by potent negative regulators of activation on nonactivating surfaces, such as the surface of host cells. Turnover of the alternative pathway is initiated either by the provision of C3b via the classical pathway, the lectin pathway, or complement-independent proteolysis of C3 or by the spontaneous hydrolysis of C3 to form C3(H₂O). C3b or C3(H₂O) bind factor B to form either the C3bB or C3(H₂O)B zymogen complex. In this complex, factor B is cleaved by factor D, releasing a Ba fragment. The activated C3bBb or C3(H₂O)Bb fragments are themselves C3 convertases, which in turn cleave more C3 into C3a and C3b. Unchecked, the accumulation of C3b rapidly leads to the formation of more alternative pathway convertase complexes, resulting in a physiologically critical positive feedback mechanism—the amplification loop of complement activation (16). The alternative pathway thus amplifies complement activation initiated by any of the three pathways, making it an attractive target for therapeutic intervention designed to modulate complement-mediated immunity and/or inflammatory processes (17).Deposition of C3b and iC3b on the bacterial surface is a key step in the immune response against S. pneumoniae, because complement-mediated opsonisation is essential for clearance of S. pneumoniae through phagocytosis (8). Lysis of bacteria, owing to formation of the membrane attack complex complex, is the critically important biological activity of complement in the defense against N. meningitidis (10). Inherited or acquired deficiencies of the alternative pathway are associated with a high risk of recurrent bacterial infection. Factor B deficiencies significantly increase the risk of S. pneumoniae and Pseudomonas aeruginosa infection (9, 18). In a mouse model of properdin deficiency, the severity of polymicrobial peritonitis was significantly greater in deficient mice compared with their WT littermates (19). Properdin deficiency in humans has been associated with a high risk of meningococcal infections, especially with unusual infective serotypes, such as W-135 and Y (10, 20, 21). In addition, opsonophagocytosis of S. pneumoniae was found to be severely compromised in properdin-deficient sera, and reconstitution of properdin-deficient sera with purified properdin restored the opsonic activity and killing of S. pneumoniae by polymorphonuclear leukocytes (22, 23).Properdin is the only known positive physiological regulator of complement activation. It stabilizes and extends the half-life of the surface-bound C3 convertase C3bBb, and inhibits its degradation by factor I (24–26). In their pioneering 1954 work, Pillemer et al. (26) first described properdin as a serum protein that mediates complement activation and antimicrobial activity in absence of antibodies.Properdin is present in serum at a concentration of ∼5–15 μg/mL (27). Unlike most other complement components, properdin is not synthesized in the liver but rather is expressed by other cells, including monocytes, T cells, mast cells, and granulocytes (19, 28–30). Properdin monomers can assemble into dimers (P₂), trimers (P₃), and tetramers (P₄), formed by head-to-tail association of monomers (each ∼53 kDa) (31, 32). Properdin aggregates, so-called “activated” properdin (P_n), are considered artificial higher-order oligomers formed during the purification of properdin from plasma or during subsequent freeze–thaw cycles (33). The functional activity of properdin increases with the size of the polymers formed (34). By increasing the half-life of the alternative pathway C3 convertase, properdin antagonizes the functional activity of complement factor H, an abundantly expressed plasma component, which promotes inactivation of the alternative pathway C3 convertase and of all C5 convertases of complement by accelerating the decay of these enzyme complexes through binding to complex-bound C3b and by serving as a cofactor in the factor I-mediated conversion of C3b to its inactive form, termed iC3b (35). Interestingly, the two pathogens used in this study were previously shown to express distinct microbial surface components that sequester factor H from host plasma, leading to resistance to the complement-mediated immune clearance of these pathogens (36, 37).In the present study, we addressed the role of the alternative pathway and the effect of administration of recombinant properdin as a tool for boosting alternative pathway activity to augment the immune response against S. pneumoniae or N. meningitidis.     

Risk factors for the formation of a steinstrasse after extracorporeal shock wave lithotripsy: a statistical model

PURPOSE: We studied the various stone, renal and therapy factors that could affect steinstrasse formation after extracorporeal shock wave lithotripsy (ESWL), Dornier Medical Systems Inc., Marietta, Georgia to define the predictive factors for its formation. Thus, steinstrasse could be anticipated and prophylactically avoided. MATERIALS AND METHODS: Between February 1989 and May 1999, 4,634 patients were treated with a Dornier MFL 5000 lithotriptor (Dornier Med Tech, GmbH, Germany). Renal stones were encountered in 3,403 patients and ureteral stones in 1,231. Steinstrasse were recorded in 184 patients, of whom 74 required intervention and formed the "complicated group." All patient data, stone and renal characteristics, and data of ESWL were reviewed. Univariate and multivariate statistical analyses of patients, stones and therapy characteristics in correlation with the incidence of steinstrasse formation were performed to assign the factors that had a significant impact on steinstrasse formation. RESULTS: The overall incidence of steinstrasse was 3.97%. The steinstrasse was in the pelvic ureter in 74% of the cases, lumbar ureter in 21.7% and iliac ureter in 4.3%. Steinstrasse incidence significantly correlated with stone size and site, the power level (kV.) used during therapy and radiological renal features. Steinstrasse was more common with renal stones more than 2 cm. in diameter in a dilated system, especially with the use of high power (greater than 22 kV.) for disintegration. A statistical model was constructed to estimate the risk of steinstrasse formation accurately. CONCLUSIONS: Stone size and site, renal morphology and shock wave energy are the significant predictive factors controlling steinstrasse formation. If a patient has a high probability of steinstrasse formation, close followup with early intervention or prophylactic pre-ESWL ureteral stenting is indicated.     

Indirect determination of captopril by AAS

An indirect method is described for the determination of captopril (KPL) in pharmaceutical preparations by atomic absorption spectrometry (AAS). The procedure is based on the complexation of KPL with an excess of Pd(II) ion. The unreacted Pd(II) was resoluted on a cationic ion-exchanger resin, while Pd(II)-KPL sequestrate was not retained. The effluent Pd(II) sequestrade was measured by AAS. The absorbance is found to increase linearly with increasing KPL concentration, because the amount of Pd(II) is related to the concentration of KPL, which is corroborate by the calculated correlation coefficient value of 0.9939. The system obeys Beer's law for 1-40 microg ml(-1), S.D. was found to be 0.039 (n = 5). The Pd(II)-KPL complex was obtained in the solid phase. Characterization of the complex was performed by elemental analysis, TG, conductance measurements and IR, 1H-NMR spectroscopy.     

Antiulcerogenic effect of some gastrointestinally acting plant extracts and their combination

Extracts from the plants Iberis amara, Melissa officinalis, Matricaria recutita, Carum carvi, Mentha x piperita, Glycyrrhiza glabra, Angelica archangelica, Silybum marianum and Chelidonium majus, singly and combined in the form of a commercial preparation, STW 5 (Iberogast) and a modified formulation, STW 5-II, lacking the last 3 constituents, were tested for their potential anti-ulcerogenic activity against indometacin induced gastric ulcers of the rat as well as for their antisecretory and cytoprotective activities. All extracts produced a dose dependent anti-ulcerogenic activity associated with a reduced acid output and an increased mucin secretion, an increase in prostaglandin E2 release and a decrease in leukotrienes. The effect on pepsin content was rather variable and did not seem to bear a relationship with the anti-ulcerogenic activity. The most beneficial effects were observed with the combined formulations STW 5 and STW 5-II in a dose of 10 ml/kg b.w., comparable with cimetidine in a dose of 100 mg/kg b.w. The anti-ulcerogenic activity of the extracts was also confirmed histologically. The cytoprotective effect of the extracts could be partly due to their flavonoid content and to their free radical scavenging properties.     

Anopheles population dynamics in two malaria endemic villages in Faiyum Governorate, Egypt

Anopheles populations were monitored for one year in 2 neighboring villages in Faiyum Governorate, Egypt, to study factors causing differences in malaria prevalence. Both villages contained the following species: Anopheles pharoensis, An. sergentii, An. multicolor and An. tenebrosus. Abundant larval breeding sites in Abheet, the village with the higher malaria rate, accounted for the higher adult densities observed from human and animal biting collections and from indoor resting collections. Anopheles pharoensis and An. sergentii were the dominant species in Abheet with seasonal biting activity extending from May to December, reaching a peak in November. In El Zawya, the village with the lower malaria rate, An. pharoensis dominated, reaching seasonal peaks in June and August. Inside houses, An. sergentii was common from May to January in Abheet, but rare in El Zawya. Anopheles pharoensis and An. sergentii were both incriminated as malaria vectors based upon their seasonal abundance and the finding of sporozoite positive specimens during the peak malaria season.