Comparison of the Kato-Katz method and ether-concentration technique for the diagnosis of soil-transmitted helminth infections in the framework of a randomised controlled trial.

Soil-transmitted helminth infections are a major public health problem. An accurate diagnosis is important in order to identify individuals and communities in need of intervention, and for monitoring drug efficacy and potential emergence of resistance. We compared the accuracy of the Kato-Katz method and ether-concentration technique for the diagnosis of soil-transmitted helminth infections within a randomised controlled trial. Quadruplicate Kato-Katz thick smears (duplicate Kato-Katz from two stool samples each) were examined before (baseline) and 3 weeks after treatment (follow-up). Additionally, at baseline and follow-up, the first stool sample was subjected to an ether-concentration method. We determined the prevalence, sensitivity, negative predictive value, diagnostic agreement and cure rates for single and duplicate Kato-Katz thick smears from the first stool sample, quadruplicate Kato-Katz thick smears produced from two stool samples and single ether-concentration as compared to our 'gold' standard (i.e. quadruplicate Kato-Katz plus ether-concentration). Quadruplicate Kato-Katz revealed a higher sensitivity than single ether-concentration for Trichuris trichiura at baseline (94.3 % vs. 88.5 %, p = 0.002) and follow-up (93.8 % vs. 83.5 %, p < 0.001). In contrary, at follow-up, ether-concentration showed a higher sensitivity than quadruplicate Kato-Katz for Ascaris lumbricoides diagnosis (86.7 % vs. 46.7 %, p = 0.012). The ether-concentration method showed similar or slightly higher sensitivity than the Kato-Katz technique based on a single stool sample for all soil-transmitted helminth infections. The estimated cure rates were heavily dependent on the diagnostic technique and sampling effort. In conclusion, data on the prevalence of soil-transmitted helminth infections and the efficacy of anthelminthics are greatly influenced by the diagnostic method and sampling effort. The ether-concentration technique is a valuable alternative to the Kato-Katz method for helminth diagnosis.

Activity of tribendimidine and praziquantel combination therapy against the liver fluke Opisthorchis viverrini in vitro and in vivo.

Opisthorchiasis, caused by the liver fluke Opisthorchis viverrini, a food-borne trematode, is an important public health problem; however, only a single drug, praziquantel is available. We investigated tribendimidine-praziquantel combinations against O. viverrini in vitro and in vivo. The IC50 values of 0.16 µg/ml and 0.05 µg/ml were determined for praziquantel and tribendimidine, respectively, against adult O. viverrini in vitro. When O. viverrini was exposed to both drugs simultaneously (using a drug ratio based on the IC50 (1:3.2)) a synergistic effect was calculated (combination index (CI) at the IC50= 0.7). A similar result was observed when drug addition in vitro was spaced by the respective half-lives of the drugs (a CI of 0.78 at the IC50 for tribendimidine followed by praziquantel and a CI of 0.47 at the IC50 for praziquantel followed by tribendimidine). In vivo median-effect dose (ED50) values of 191 mg/kg and 147 mg/kg were calculated for praziquantel and tribendimidine, respectively. Low to moderate worm burden reductions (38-62%) were observed in O. viverrini infected hamsters when both drugs were administered simultaneously or on subsequent days, pointing to antagonistic effects in vivo. Further studies are necessary to understand the striking differences between the in vitro and in vivo observations using combinations of praziquantel and tribendimidine on O. viverrini.

Schistosoma mansoni tetraspanning orphan receptor (SmTOR): a new vaccine candidate against schistosomiasis.

One approach to fight against schistosomiasis is to develop an efficient vaccine. Schistosoma mansoni tetraspanning orphan receptor (SmTOR) might be a vaccine candidate, as it is a tegument membrane protein expressed most highly in cercariae. In this study we characterized the recombinant first extracellular domain of SmTOR (rSmTORed1) as having the expected property to bind C2 of complement similarly to a smaller peptide of the same domain, and to produce specific and high-titre antibodies in BALB/c mice immunized using complete Freund's adjuvant/incomplete Freund's adjuvant (CFA/IFA). Immunization was protective against parasite infection, as demonstrated by a significant decrease in worm burden in immunized BALB/c mice versus the control groups over two independent trials [64 and 45% reduction for mean adult worm burden in immunized versus phosphate-bufferd saline (PBS) injected mice]. Interestingly, infection by itself did not lead to the generation of anti-rSmTORed1 antibodies, corresponding to the low frequency of specific anti-rSmTORed1 antibodies detected in the sera of patients infected with S. mansoni (2/20; 10%). These data suggest that, as opposed to the natural infection during which SmTOR induces antibodies only rarely, immunization with its smaller first extracellular domain might be more efficient.

In vitro and in vivo trematode models for chemotherapeutic studies.

Schistosomiasis and food-borne trematodiases are chronic parasitic diseases affecting millions of people mostly in the developing world. Additional drugs should be developed as only few drugs are available for treatment and drug resistance might emerge. In vitro and in vivo whole parasite screens represent essential components of the trematodicidal drug discovery cascade. This review describes the current state-of-the-art of in vitro and in vivo screening systems of the blood fluke Schistosoma mansoni, the liver fluke Fasciola hepatica and the intestinal fluke Echinostoma caproni. Examples of in vitro and in vivo evaluation of compounds for activity are presented. To boost the discovery pipeline for these diseases there is a need to develop validated, robust high-throughput in vitro systems with simple readouts.

Morphological effects and tegumental alterations induced by mefloquine on schistosomula and adult flukes of Schistosoma mansoni.

There is a pressing need to develop novel anti-schistosomal drugs, as current treatment relies largely on praziquantel (PZQ). To further strengthen current evidence of the anti-schistosomal properties of mefloquine (MQ), we studied the temporal effect of this compound in vitro and in vivo, and examined alterations on the tegumental surface of schistosomula and adults of S. mansoni by means of scanning electron microscopy (SEM). Schistosomula and adults were each incubated in vitro using MQ over a wide concentration range (1-100 microg/ml). In addition, mice infected with adult S. mansoni were treated with a single oral dose of 400 mg/kg MQ, and worms were recovered 24, 48, 72, 96 and 120 h following treatment. MQ showed a rapid onset of action on schistosomula in vitro; 100 and 75 microg/ml of MQ killed schistosomula immediately; the minimal lethal and effective concentrations of MQ on schistosomula after 1 h were 25 and 5 microg/ml, respectively. Adult worms incubated with 100 and 10 microg/ml of MQ were dead after 1 h and 24 h of incubation, respectively. A hepatic shift of adult schistosomes was observed in mice already 24 h after treatment, and 120 h following treatment >98% of all worms had translocated to the liver. SEM observations revealed extensive tegumental destruction, including blebbing, shrinking and sloughing, particularly following in vitro incubation and on the tegument of female worms.

Aluminum absorption and distribution: effect of parathyroid hormone.

In rats, gastrointestinal aluminum absorption and tissue distribution were altered by parathyroid hormone; the resultant tissue concentrations were similar to those observed in dialysis patients with a fatal encephalopathy. In dialysis patients, serum aluminum and endogenous parathyroid hormone concentrations are significantly correlated. These data suggest that aluminum toxicity in dialysis patients results from oral aluminum ingestion in the presence of hyperparathyroidism.

Electron microscopical study to assess the in vitro effects of the synthetic trioxolane OZ78 against the liver fluke, Fasciola hepatica.

Adult Fasciola hepatica were incubated for 48 h in vitro in the synthetic peroxide, OZ78 at a concentration of 100 microg/ml and then prepared for scanning and transmission electron microscopy. There was limited disruption to the external fluke surface, with only slight swelling and blebbing of the interspinal tegument in the midbody and ventral tail regions. By contrast, significant disruption was observed to the ultrastructure of the tegument and subtegumental tissues. There was severe swelling of the basal infolds in the tegumental syncytium and the flooding spread internally to affect the subtegumental tissues. In the tegumental system, there was swelling of the cisternae of granular endoplasmic reticulum and of the mitochondria, with the latter showing signs of breaking down. Autophagic vacuoles and lipid droplets were present and the synthesis of tegumental secretory bodies was much reduced. The gastrodermal cells were severely affected, with swelling and degeneration of the mitochondria and the presence of autophagic vacuoles and lipid droplets. The granular endoplasmic reticulum was swollen and vesiculated and the cells contained few secretory bodies. Both the vitelline and testis follicles showed evidence of extensive cellular disruption and degeneration. This study confirms previous data indicating the potential flukicidal activity of OZ78.

Adult triclabendazole-resistant Fasciola hepatica: morphological changes in the tegument and gut following in vivo treatment with artemether in the rat model.

A study has been carried out to determine the morphological changes to the adult liver fluke, Fasciola hepatica after treatment in vivo with artemether. Rats were infected with the triclabendazole-resistant Sligo isolate of F. hepatica, dosed orally with artemether at a concentration of 200 mg/kg and flukes recovered at 24, 48 and 72 h post-treatment (p.t.). Surface changes were monitored by scanning electron microscopy and fine structural changes to the tegument and gut by transmission electron microscopy. Twenty-four hours p.t., the external surface showed minor disruption, in the form of mild swelling of the tegument. The tegumental syncytium and sub-tegumental tissues appeared relatively normal. Forty-eight and seventy-two hours p.t., disruption to the tegumental system increased, with isolated patches of surface blebbing and reduced production of secretory bodies by the tegumental cells being the main changes seen. The gastrodermal cells showed a relatively normal morphology 24 h p.t. By 48 h, large numbers of autophagic vacuoles and lipid droplets were present. Autophagy increased in magnitude by 72 h p.t. and substantial disruption to the granular endoplasmic reticulum was observed. Results from this study show that flukes treated in vivo with artemether display progressive and time-dependent alterations to the tegument and gut. Disruption to the gut was consistently and substantially more severe than that to the tegument, suggesting that an oral route of uptake for this compound predominates. This is the first study providing ultrastructural information on the effect of an artemisinin compound against liver fluke.

Effect of dengue vector control interventions on entomological parameters in developing countries: a systematic review and meta-analysis.

The aim of this review was to compare the effects of different dengue vector control interventions (i.e. biological control, chemical control, environmental management and integrated vector management) with respect to the following entomological parameters: Breteau index (BI), container index (CI), and house index (HI). We systematically searched PubMed, ISI Web of Science, Science Direct, the Dengue Bulletin of the World Health Organization and reference lists of retrieved articles on dengue vector control interventions in developing countries. We extracted data on the effectiveness of different dengue vector control interventions (defined as the relative reduction of an entomological measure caused by the intervention compared with the control or pre-intervention phase) and calculated a measure of combined relative effectiveness, with 95% confidence intervals (95% c.i.). We identified 56 publications covering 61 dengue vector control interventions. Integrated vector management was found to be the most effective method to reduce the CI, HI and BI, resulting in random combined relative effectiveness values of 0.12 (95% c.i. 0.02-0.62), 0.17 (95% c.i. 0.02-1.28) and 0.33 (95% c.i. 0.22-0.48), respectively. Environmental management showed a relatively low effectiveness of 0.71 (95% c.i. 0.55-0.90) for the BI, 0.49 (95% c.i. 0.30-0.79) for the CI and 0.43 (95% c.i. 0.31-0.59) for the HI. Biological control (relative effectiveness for the CI: 0.18) usually targeted a small number of people (median population size: 200; range 20-2500), whereas integrated vector management focused on larger populations (median: 12 450; range: 210-9 600 000). In conclusion, dengue vector control is effective in reducing vector populations, particularly when interventions use a community-based, integrated approach, which is tailored to local eco-epidemiological and sociocultural settings and combined with educational programmes to increase knowledge and understanding of best practice. New research should assess the density-dependent effectiveness of each control measure in order to estimate whether reducing vector numbers has an impact on dengue transmission when populations are at a critical threshold.

Electromagnetic guidance for catheter-based transendocardial injection: a platform for intramyocardial angiogenesis therapy. Results in normal and ischemic porcine models.

OBJECTIVES: To test the feasibility of myocardial angiogenic gene expression using a novel catheter-based transendocardial injection system. BACKGROUND: Angiogenesis has been induced by direct injection of growth factors into ischemic myocardium during open-heart surgery. Catheter-based transendocardial injection of angiogenic factors may provide equivalent benefit without need of surgery. METHODS: A new guidance system for intramyocardial therapy utilizes magnetic fields and catheter-tip sensors to locate a position in space and reconstruct three-dimensional left ventricular (LV) electromechanical maps without using fluoroscopy. A retractable 27G needle was coupled with the guidance system for LV transendocardial injection. In 12 pigs, the catheter was used to inject 0.1 ml of methylene-blue (MB) dye and 8 pigs had myocardial injections of adenoviral vector (1 x 10(10) particles per site) containing the LacZ transgene. Ten pigs underwent catheter-based transendocardial injection and six pigs were injected using transepicardial approach with the gene encoding adenovirus vascular endothelial growth factor-121 (Ad.VEGF121; 1 x 10(10) viral particles x 6 sites) and sacrificed at 24 h. Injection sites were identified with ultraviolet light by coinjection of fluorescent beads. RESULTS: Overall, 138 of 152 attempted injection MB tracks (91%) were found after sacrifice. Tissue staining was 7.1+/-2.1 mm in depth and 2.3+/-1.8 mm in width. No animal had pericardial effusion or tamponade. In Ad.LacZ injected animals, gross pathology showed positive staining in injected zones, and histology confirmed positive myocyte staining. Adenovirus vascular endothelial growth factor-121 injected sites showed high levels of VEGF121 production that was of similar magnitude whether injected using the transendocardial (880.4+/-412.2 pg VEGF121/mg protein) or transepicardial (838.3+/-270 pg VEGF121/mg protein) delivery approach (p = 0.62). CONCLUSIONS: Using this magnetic guidance catheter-based navigational system, transgenes can effectively be transfected into designated myocardial sites. Thus, if it is determined that direct intramyocardial injection of angiogenic factors enhances collateral function in patients, this less invasive catheter-based system offers a similar gene delivery efficiency and, thus, may have clear advantages compared with the surgically-based transepicardial injection approach.

Flavimonas oryzihabitans (Pseudomonas oryzihabitans; CDC group Ve-2) bacteremia in the immunocompromised host.

Flavimonas oryzihabitans, known previously as Pseudomonas oryzihabitans, and a member of the Centers for Disease Control group Ve-2, is a gram-negative organism that has rarely been implicated as a human pathogen. Flavimonas oryzihabitans appears to be a soil and saprophytic organism that survives in moist environments and is indigenous to rice paddles. To our knowledge, only seven cases of human infection caused by this organism have been reported; they involved four patients with bacteremia and three patients with peritonitis who were receiving continuous ambulatory peritoneal dialysis. In this report, we describe three immunocompromised patients with catheter-associated bacteremia: a patient with cancer, a patient with acquired immunodeficiency syndrome, and a patient with sickle cell disease. There is emerging clinical evidence that F oryzihabitans should be recognized as an organism that is capable of causing human disease, particularly in immunocompromised patients and with the increased usage of permanent catheters.

Detection of cytomegalovirus proteins by flow cytometry in the blood of patients undergoing hematopoietic stem cell transplantation.

Cytomegalovirus (CMV) infection and associated diseases continue to be a major complication encountered by patients undergoing high-dose chemoradiotherapy and hematopoietic stem cell transplantation (HSCT). A number of studies revealed that identification of CMV in the blood of HSCT patients was a predictor of future CMV disease. The purpose of this study was to determine if CMV proteins detected by flow cytometry could be a rapid and more quantitative way to monitor CMV infections and CMV antigenemia in HSCT patients. Preliminary studies showed that CMV immediate early (IE), early (E), and late (L) tegument proteins were specifically identified in CMV-infected cell lines and not in uninfected cells. We evaluated CMV antigen detection by flow cytometry in blood samples collected before and after transplantation in 56 serially collected blood samples from 17 HSCT patients and CMV protein expression was compared to CMV isolation. CMV IE and E proteins were not detected in any of the samples analyzed. However, CMV L protein detection by flow cytometry correlated with virus isolation in serially collected blood samples. Samples from 14 patients were evaluated by both techniques, at the same time intervals. There was a 100% correlation (8/8) between the lack of CMV antigen detection by flow cytometry and the failure to isolate infectious virus. Moreover, 5 of 6 patients who were positive for CMV L antigen by flow cytometry also were positive by virus isolation techniques. When flow cytometry and virus isolation did not detect CMV antigen on the same day, CMV positivity was first detected by flow cytometry. Then, 1-2 weeks later, positive virus isolation was documented. This study indicates that flow cytometric identification of CMV antigenemia correlates with isolation of CMV in HSCT patients and may be a predictive test for the rapid detection of CMV in the blood.

Endothelin antagonists improve renal function in spontaneously hypertensive rats.

Hypertension in the spontaneously hypertensive rat (SHR) is associated with reduced renal excretory function, low renal plasma flow, reduced glomerular filtration rate, and reduced renal interstitial hydrostatic pressure. The mechanisms responsible for these abnormalities in renal function are unknown. The purpose of this study was to determine the role of intrarenal endothelin in altering renal hemodynamic and excretory function in the SHR. Both PD 145065 (an endothelin A and B receptor antagonist) and FR 139317 (a selective endothelin A receptor antagonist) or saline was infused into the renal interstitium of 14- to 16-week-old SHR (n = 7) and age-matched Wistar-Kyoto rats (WKY) (n = 7). Renal perfusion pressure in some SHR was reduced to that of the WKY by a servocontrol system. At a renal perfusion pressure of 124 +/- 4 mm Hg, infusion of PD 145065. (0.03 mg.kg-1.min-1) and FR 139317 (0.02 mg.kg-1.min-1) significantly increased glomerular filtration rate (delta 22%), renal plasma flow (delta 37%), and renal interstitial hydrostatic pressure (from 3.2 +/- 0.5 to 5.4 +/- 0.6 mm Hg) in the SHR. These changes were associated with significant increases in urine flow, absolute sodium excretion, and fractional excretion of sodium. Similar improvements in renal plasma flow, renal interstitial hydrostatic pressure, and renal excretory function were obtained in the SHR whose renal perfusion pressure was not reduced (n = 7). Renal interstitial infusion of endothelin receptor antagonists had no effect on renal hemodynamic or excretory function in the WKY. These data demonstrate that endothelin receptor blockade within the kidney improves renal hemodynamic and excretory function in the SHR.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin II and renal functional reserve in rats with Goldblatt hypertension.

We have previously demonstrated that loss of renal functional reserve (renal response to protein loading) in two-kidney, one clip Goldblatt hypertension is characterized by no change in glomerular filtration rate or single nephron glomerular filtration rate and decreased absolute proximal tubular reabsorption during glycine administration. Captopril restores proximal reabsorption and renal functional reserve in this condition. Because captopril suppresses angiotensin II generation and increases bradykinin, prostaglandins, and potentially nitric oxide, we have investigated the role of angiotensin II blockade in restoring proximal reabsorption and renal functional reserve by comparing captopril with DuP 753, an angiotensin II receptor antagonist, in Goldblatt rats. One month after clipping, two period micropuncture studies (control and glycine) were performed on the unclipped kidney. Normal rats and three groups of clipped rats were studied: an untreated group (HYP), a group treated with captopril (CEI), and a group treated with DuP 753 (DuP) 5 days before micropuncture. Glycine increased glomerular filtration rate, nephron plasma flow, and single nephron glomerular filtration rate in normal rats. Systemic and glomerular hypertension in HYP rats was associated with loss of renal functional reserve and a decrease in absolute proximal reabsorption during glycine. Captopril and DuP 753 normalized systemic and glomerular capillary pressure and prevented the decrease in proximal reabsorption during glycine; however, only CEI rats increased single nephron glomerular filtration rate and glomerular filtration rate after glycine. In conclusion, abnormal responses of both glomerular and tubular function are responsible for the loss of renal functional reserve in Goldblatt rats. Inhibitory angiotensin II activity is responsible for decreasing proximal reabsorption during glycine; however, factors other than angiotensin II limit the glomerular response to glycine.(ABSTRACT TRUNCATED AT 250 WORDS)

Role for endothelin-1 in angiotensin II-mediated hypertension.

Experiments in cultured vascular smooth muscle cells have shown that angiotensin II (Ang II) stimulates expression of endothelin-1. We sought to examine role of endothelin-1 in the effects of Ang II in vivo. Ang II infusion in rats (0.7 mg/kg per day for 5 days) was associated with marked increases in vascular smooth muscle endothelin-1 levels, as assessed by immunostaining. Administration of the selective endothelin type A (ET(A)) receptor antagonist PD 155080 (50 mg/kg per day) abrogated the hypertensive response to a 5-day infusion of Ang II (0.7 mg/kg per day), as did losartan (25 mg/kg per day). ET(A) receptor blockade during Ang II-mediated hypertension was associated with marked elevations of plasma endothelin-1 levels. Ang II-mediated hypertension was associated with heightened vascular responsiveness to a variety of vasoconstrictor agents except endothelin-1. Blockade of ET(A) receptor invariably corrected this vasoconstrictor hyperresponsiveness. We conclude that some of the vascular effects of Ang II thought to be unique to this hormone are likely mediated by endothelin-1.

Subclasses of cyclic GMP-specific phosphodiesterase and their role in regulating the effects of atrial natriuretic factor.

Two subclasses of cyclic guanosine monophosphate (GMP)-specific phosphodiesterases were identified in vascular tissue from several beds. The activity of one subclass (phosphodiesterase IB) was stimulated severalfold by calmodulin and selectively inhibited by the phosphodiesterase inhibitor TCV-3B. The activity of the other subclass (phosphodiesterase IC) was not stimulated by calmodulin and was selectively inhibited by the phosphodiesterase inhibitor M&B 22,948. To assess the involvement of both subclasses in regulating cyclic GMP-dependent responses, the ability of TCV-3B and M&B 22,948 to potentiate the in vitro and in vivo responses to the endogenous guanylate cyclase stimulator atrial natriuretic factor (ANF) was evaluated. Both TCV-3B and M&B 22,948 relaxed isolated rabbit aortic and pulmonary artery rings and also potentiated the relaxant effect of ANF. In addition, both inhibitors produced small increases in urine flow and sodium excretion in anesthetized rats and potentiated the diuretic and natriuretic responses to exogenous ANF. M&B 22,948 (30 micrograms/kg/min) produced a threefold increase in the natriuretic response to simultaneously administered ANF, and TCV-3B (10 micrograms/kg/min) produced a twofold increase in the response to ANF. The results of the present experiments suggest that both the calmodulin-sensitive and calmodulin-insensitive subclasses of cyclic GMP-specific phosphodiesterase play a role in regulating the in vitro and in vivo response to ANF.

New drugs for the treatment of human African trypanosomiasis: research and development.

Chemotherapy of human African trypanosomiasis is problematic because of the high frequency of severe adverse events, the long duration and high cost of treatment, and an increasing number of treatment-refractory cases. New cost-efficient, easy-to-use drugs are urgently needed. Whereas basic research on potential drug targets is anchored in academia, the complex, highly regulated and very expensive process of preclinical and clinical drug development is almost exclusively in the hands of pharmaceutical companies. Jennifer Keiser, August Stich and Christian Burri here review, from the angle of industrial drug research and development, the past ten years of research activities at different stages of the development of trypanocidal drugs, and assess future prospects. The absence of compounds in clinical development Phases I-III indicates no new drugs will become available in the next few years.

Investigations of the metabolites of the trypanocidal drug melarsoprol.

BACKGROUND: Melarsoprol remains the first-choice drug for trypanosomiasis (human African sleeping sickness). To contribute to the sparse pharmacologic data and to better understand the cause of the frequent serious adverse reactions, we investigated the metabolism of this 50-year-old organoarsenic compound. RESULTS: The half-life of melarsoprol determined by HPLC was <1 hour compared with 35 hours determined by bioassay and atomic absorption spectroscopy, indicating the existence of active metabolites. One metabolite, melarsen oxide, was identified by ultraviolet HPLC after incubation of melarsoprol with microsomes. The maximum plasma concentration of melarsenoxide was reached 15 minutes after administration; the clearance was 21.5 mL/min/kg and the half-life of free melarsen oxide was 3.9 hours. Either melarsen oxide or a yet-undiscovered active metabolite is irreversibly bound to proteins, as shown by ultrafiltration, precipitation experiments, and atomic absorption spectroscopy. Because of the poor pharmaceutical properties of melarsoprol, the therapeutic potential of melarsen oxide was investigated. In a rodent model of acute infection, 20 of 20 mice were cured (0.1 to 1 mg/kg intravenously or 2.2 mg/kg intraperitoneally). In a rodent model of central nervous system infection, five of six mice survived for more than 180 days (5 mg/kg intravenously), indicating a sufficient melarsen oxide penetration across the blood-brain barrier. CONCLUSION: The prospects for the future of trypanosomiasis treatment are deplorable. Investigations on the improvement of the use of the old drugs are therefore required. The results of this study may build a basis for further research on the cause of severe adverse reactions.

Current progress in the development and use of artemether for chemoprophylaxis of major human schistosome parasites.

Human schistosomiasis, a chronic and debilitating parasitic disease of the tropics, is ranked second after malaria in terms of public health importance. At present, there is no vaccine available, and chemotherapy is the cornerstone of schistosomiasis control. Praziquantel is the drug of choice. Oxamniquine has become difficult to obtain and metrifonate has recently been withdrawn from the market. Rapid re-infection following treatment and concern about praziquantel resistance called for the search of novel drugs for prevention and cure of schistosomiasis. Significant progress has been made with artemether, the methyl ether of dihydroartemisinin, already widely used for the treatment of malaria. The present article reviews the literature that led to the development of artemether for chemoprophylaxis in schistosomiasis, and it summarises the experiences so far obtained with its use to control schistosomiasis in different endemic settings. Topics covered include an overview of the global burden of schistosomiasis and approaches for its control; the nature and features of artemisinin and related derivatives, initially discovered as antimalarials, other bioactivities, and their recent discovery of antischistosomal properties; a historic account disclosing the antischistosomal activity of artemether; in vivo assessment of drug susceptibility of different developmental stages of schistosome parasites; artemether-induced pathology evidenced by scanning and transmission electron microscopy; the possible mechanism of action; in vivo studies with combination therapy of artemether and praziquantel; results of randomised controlled clinical trials of oral artemether for the prevention of patent infection and morbidity; and, ultimately the translation of this knowledge into public health action in different endemic settings towards a more integrated approach of schistosomiasis control.

Influence of lipoprotein(a) plasma concentration on neointimal growth in a monkey model of vascular injury.

Lipoprotein(a) [Lp(a)] has been proposed as a risk factor for both restenosis and coronary heart disease. Recently, we identified Lp(a) in the arterial wall during the initial rapid neointimal growth phase that occurs after balloon injury in cynomolgus monkeys. The purpose of this study was to determine the relationship between circulating Lp(a) levels and the extent of early neointimal formation. Initially, 348 cynomolgus monkeys were screened to identify 15 monkeys that had either high or low circulating Lp(a) levels. In the 15 monkeys, circulating Lp(a) levels were confirmed by two separate measurements over 6 weeks using an immunoturbidimetric assay. Cohorts were identified with plasma Lp(a) levels that differed by four fold. Lp(a) levels expressed as total mass averaged 32 +/- 4 (N = 8) and 136 +/- 12 (N = 7) mg/dl in the low and high groups, respectively. Between the two assays absolute Lp(a) levels differed by less than 6%. Iliac arteries were harvested 14 days after injury induced by expansion of the internal vessel diameter 1.4 times its initial size with an angioplasty balloon. The neointimal area in the high Lp(a) monkeys was 16% greater (0.49 +/- 0.12 mm2, N = 8 versus 0.57 +/- 0.10 mm2, N = 7) than in the low animals; however, this difference was not statistically significant (P = 0.63). Medial areas averaged 1.27 +/- 0.11 and 1.44 +/- 0.20 mm2 (P = 0.48) in these groups, respectively. Tissue Lp(a) quantification, using a mouse monoclonal anti-Lp(a) antibody, indicated that the percent total area staining positive for Lp(a) was 1.7-fold higher in the high versus the low Lp(a) group (2.7 +/- 0.4% versus 1.6 +/- 0.4%, N = 6-8); this difference was not statistical significant (P = 0.28). In summary, a four-fold increase in circulating plasma Lp(a) levels did not result in a statistically significant enhanced neointimal formation at 14 days after balloon injury. This finding suggests that studies of longer duration may be needed to amplify the trend toward increased neointimal growth observed in this study.