STAT3 modulation to enhance motor neuron differentiation in human neural stem cells

Spinal cord injury or amyotrophic lateral sclerosis damages spinal motor neurons and forms a glial scar, which prevents neural regeneration. Signal transducer and activator of transcription 3 (STAT3) plays a critical role in astrogliogenesis and scar formation, and thus a fine modulation of STAT3 signaling may help to control the excessive gliogenic environment and enhance neural repair. The objective of this study was to determine the effect of STAT3 inhibition on human neural stem cells (hNSCs). In vitro hNSCs primed with fibroblast growth factor 2 (FGF2) exhibited a lower level of phosphorylated STAT3 than cells primed by epidermal growth factor (EGF), which correlated with a higher number of motor neurons differentiated from FGF2-primed hNSCs. Treatment with STAT3 inhibitors, Stattic and Niclosamide, enhanced motor neuron differentiation only in FGF2-primed hNSCs, as shown by increased homeobox gene Hb9 mRNA levels as well as HB9+ and microtubule-associated protein 2 (MAP2)+ co-labeled cells. The increased motor neuron differentiation was accompanied by a decrease in the number of glial fibrillary acidic protein (GFAP)-positive astrocytes. Interestingly, Stattic and Niclosamide did not affect the level of STAT3 phosphorylation; rather, they perturbed the nuclear translocation of phosphorylated STAT3. In summary, we demonstrate that FGF2 is required for motor neuron differentiation from hNSCs and that inhibition of STAT3 further increases motor neuron differentiation at the expense of astrogliogenesis. Our study thus suggests a potential benefit of targeting the STAT3 pathway for neurotrauma or neurodegenerative diseases.

[The vibrio-static test with niclosamide to identify bacteria of genus Vibrio]

The new vibrio-static niclosamide (CAS No 50-65-7) is revealed. The vibrio-static test with niclosamide (10 mkg/disc) to identify bacteria of genus Vibrio is developed. This test by its diagnostic sensitivity surpasses the vibrio-static test with vibrio-static O129 since it suppresses growth of vibrios having cross resistance to O129 and co-trimoxazole. The vibrio-static test with niclosamide made it possible to identify all examined strains of V. metschnikovii, V. vulnificus, V. parahaemolyticus, V. cholerae non O1/non O139.

[Effects of molluscicides at different environments on Oncomelania hupensis snail control in Danyang City]

OBJECTIVE

To evaluate the effects of continuous application of niclosamide ethanolamine salt on Oncomelania hupensis snail control in a marshland, river and channel.

METHODS

The Beiwei marshland in Houxiang Town, the Xiaoliang River in Lingkou Town and Laomiao channel in Yunyang Town in Danyang City were selected as study sites, and 4% niclosamide ethanolamine salt and 26% niclosamide powder were used to kill the snails. Based on the historical records and field investigations, the effects of continuous application of niclosamide ethanolamine salt on snail control were evaluated.

RESULTS

Compared with the first time of snail repetition, the snail areas decreased by 82.80%, 63.14% and 70.00% in the Beiwei marshland, Xiaoliang River and Laomiao channel, respectively, in 2013. There was a positive correlation between the area and density of snails (r = 0.931, 0.975 and 0.916, respectively; all P values < 0.05). The average densities of living snails decreased significantly by 92.34%, 87.91% and 97.66%, respectively. There was a negative correlation between the corrected mortality of snails and the average density of living snails in the following year, and a negative correlation between the reduction rate of living snail density and the average density of living snails in the following year.

CONCLUSION

Molluscicides plays an important role in compressing the snail area, reducing the snail density, and controlling the schistosomiasis transmission.

The anthelmintic drug niclosamide induces apoptosis, impairs metastasis and reduces immunosuppressive cells in breast cancer model

Breast carcinoma is the most common female cancer with considerable metastatic potential. Discovery of new therapeutic approaches for treatment of metastatic breast cancer is still needed. Here, we reported our finding with niclosamide, an FDA approved anthelmintic drug. The potency of niclosamide on breast cancer was assessed in vitro and in vivo. In this investigation, we found that niclosamide showed a dramatic growth inhibition against breast cancer cell lines and induced apoptosis of 4T1 cells in a dose-dependent manner. Further, Western blot analysis demonstrated the occurrence of its apoptosis was associated with activation of Cleaved caspases-3, down-regulation of Bcl-2, Mcl-1 and Survivin. Moreover, niclosamide blocked breast cancer cells migration and invasion, and the reduction of phosphorylated STAT3(Tyr705), phosphorylated FAK(Tyr925) and phosphorylated Src(Tyr416) were also observed. Furthermore, in our animal experiments, intraperitoneal administration of 20 mg/kg/d niclosamide suppressed 4T1 tumor growth without detectable toxicity. Histological and immunohistochemical analyses revealed a decrease in Ki67-positive cells, VEGF-positive cells and microvessel density (MVD) and an increase in Cleaved caspase-3-positive cells upon niclosamide. Notably, niclosamide reduced the number of myeloid-derived suppressor cells (MDSCs) in tumor tissues and blocked formation of pulmonary metastases. Taken together, these results demonstrated that niclosamide may be a promising candidate for breast cancer.

[Field evaluation of a novel plant molluscicide "Luo-wei" against Oncomelania hupensis IV molluscicidal effect in field of river beach in Dongzhi County, Anhui Province]

OBJECTIVE

To evaluate the field effect of the plant molluscicide "Luo-wei" (tea-seed distilled saponins, TDS) against the snail Oncomelania hupensis in the river beach in Anhui Province.

METHODS

The immersing and spraying experiments were carried out in the river beach in Dongzhi County, Anhui Province, to assess the molluscicidal effect of 4% TDS comparing with 50% wettable powder of niclosamide ethanolamine salt (WPN). The chi(2) test or Fish's exact test was used to examine the differences between or among the molluscicidal effects by different environments, molluscicides, application methods, or days after the intervention. Meanwhile, the cost-effectiveness of the two molluscicides was analyzed.

RESULTS

After 1, 2 , 3 d and 7 d of the immersion, the snail death rates in both TDS group and WPN group increased gradually, the snail death rates in the two groups after immersing for 7 d were 94.62% and 99.24%, respectively, and there was no significant difference between them ( chi(2) = 3.30, P > 0.05). After 1 , 3 , 7 d and 15 d of spraying, the snail death rates were 70.82%, 79.75%, 85.11% and 91.65% in the TDS group, and 77.71%, 84.27%, 91.90% and 95.58% in the WPN group, respectively, and the differences among the snail death rates of the two groups at each time point were statistically significant (all P values < 0.05). The costs of spraying were 316.71 yuan per 100 m2 for TDS and 309.71 for WPN.

CONCLUSIONS

The molluscicidal effect of TDS has reached the requirements of national standard on nature source pesticides in the river beach of the middle and lower reaches of the Yangtze River. It is necessary to further evaluate its cost-effectiveness in large-scale field experiments in the future.

[Effect of a novel plant molluscicide "Luo-wei" against Oncomelania hupensis in plateau mountain areas]

OBJECTIVE

To evaluate the effect of a novel plant molluscicide, 4%"Luo-wei" (Tea-seed distilled saponins, TDS) against Oncomelania hupensis snails in plateau mountain areas in Yunnan Province.

METHODS

The immersing and spraying experiments were carried out in the ditches and grassland of Xiaolian Administrative Village in Heqing County, Yunnan Province, to assess the molluscicidal effect of 4% TDS comparing with 50% wettable powder of niclosamide ethanolamine salt (WPN) in different environments and time.

RESULTS

After immersion for 24, 48 h and 72 h, the snail death rates were 70.67%, 87.33% and 98.67% in the TDS group, whereas being 77.33%, 96.67% and 100.00% in the WPN group, respectively. The differences of the death rates between the two groups 24 h and 72 h after immersing were not statistically significant ( chi2(24h) =1.73, chi2(72h) = 2.01, both P values > 0.05). Seven days after the immersing experiments, the occurrence rate of frames with living snails and the death rate of snails were 20.00% and 93.03% in the TDS group, while those were 13.33% and 95.76% in the WPN group, and there were no significant differences of the 2 indexes between the 2 groups ( chi(2)(Occurrence rate) = 2.27, chi(2)(Death rate) = 0.94, all P values > 0.05). After spraying for 1, 3, 7 d and 15 d, in both groups, the occurrence rates of frames with living snails and the average densities of living snails gradually declined, while the death rates of snails gradually increased with the extension of time. There were no statistically significant differences of the above 3 indexes between the 2 groups (all P values > 0.05). Fifteen days after the spraying experiment, the occurrence rate of frames with living snails and the adjusted death rate of snails were 15.00% and 87.39% in the TDS group and those were 16.67% and 89.32% in the WPN group, respectively.

CONCLUSION

The molluscicidal effect of TDS is satisfying in plateau mountain areas, and the molluscicide is worthy of further extension and application.

Identification of three antiviral inhibitors against Japanese encephalitis virus from library of pharmacologically active compounds 1280

Japanese encephalitis virus (JEV) can cause severe central nervous disease with a high mortality rate. There is no antiviral drug available for JEV-specific treatment. In this study, a cytopathic-effect-based, high-throughput screening assay was developed and applied to screen JEV inhibitors from Library of Pharmacologically Active Compounds 1280. The antiviral effects of three hit compounds including FGIN-1-27, cilnidipine, and niclosamide were evaluated in cells by western blotting, indirect immunofluorescence assay, and plaque reduction assay. A time-of-addition assay proved that all three compounds inhibited JEV at the stage of replication. The EC50s of FGIN-1-27, cilnidipine, and niclosamide were 3.21, 6.52, and 5.80 µM, respectively, while the selectivity indexes were 38.79, 30.67, and 7.49. FGIN-1-27 and cilnidipine have high efficiency and selectivity against JEV. This study provided two JEV antiviral inhibitors as candidates for treatment of JEV infection.

[Molluscicidal effects of nano-silver biological molluscicide and niclosamide]

OBJECTIVE

To evaluate the molluscicidal effect of a novel nano-silver biological molluscicide in the field and its toxicity to other aquatic organisms.

METHODS

A marshland of the Qiupu River was selected as the study site. Four 1 m3 pools were excavated. Four groups, including 300 g/m3 and 600 g/m3 nano-silver biological molluscicide groups, a 2 g/m3 50% niclosamide group, and a natural water (control) group were assigned to the four pools which had 100 Oncomelania hupensis snails and 100 crucian seedlings. The molluscicidal effects and toxicity to the aquatic organisms were observed.

RESULTS

The snail death rates were 100% and crucian seedling death rates were 6% in the 600 g/m3 nano-silver biological molluscicide group and 300 g/m3 nano-silver biological molluscicide group in 7 days and 14 days. The snail death rate was 100% in the niclosamide group in 7 days, and the crucian seedling death rate was 100% in the niclosamide group in 3 days. The snail death rates were 7% and 14% in the control group in 7 and 14 days respectively, and the crucian seedling death rate was 22% in the control group.

CONCLUSIONS

The novel nano-silver biological molluscicide possesses an excellent molluscicidal capability and non-toxicity to the other aquatic organisms. Therefore, it may become a new, efficient and environment-friendly bio-molluscicide for extensive application.

[Preparation and molluscicidal effect of 5% niclosamide ethanolamine granules]

OBJECTIVE

To explore the preparation of 5% niclosamide ethanolamine granules and evaluate its molluscicidal effect.

METHODS

The optimal formula was obtained by the selection of wetting agents, dispersants, adhesives and carriers. The molluscicidal effect of 5% niclosamide ethanolamine granules was measured by the spray methods in the laboratory and field.

RESULTS

The mixed 5% niclosamide ethanolamine, 0.2% sodium lauryl sulfate, and 1% alkylphenol sulfonic polyxyethylene ether sulfonate were crushed by gas flow, and then mixed with 93.7% quartz sand and 0.1% polyvinyl alcohol water solution, drying to 5% niclosamide ethanolamine granules. The density, bulk density, and moisture of 5% niclosamide ethanolamine granules were 1.4 g/ml, 1.3 g/ml, and 2.4%, respectively, and the hot storage stability was qualified. Under the lab condition, the death rates of Oncomelania hupensis snails sprayed with 0.5 g/m2 (7 d) or 1.0 g/m2 (1 d) of 5% niclosamide ethanolamine granules were higher than 95%. In the field, the death rates of the snails sprayed with 0.5 g/m2 (7 d) or 1.0 g/m2 (1 d) were higher than 85%.

CONCLUSION

There is a high molluscicidal effect of 5% niclosamide ethanolamine granules and it is suitable for field application.

[Field evaluation of a novel plant molluscicide "Luo-wei" against the snail Oncomelania hupensis III molluscicidal effect by spraying method in hilly regions]

OBJECTIVE

To evaluate the molluscicidal effect of a novel plant molluscicide "Luo-wei" (Tea-seed distilled saponins, TDS) against Oncomelania httpensis in billy regions.

METHODS

The molluscicidal effect of TDS at a dose of 5 g/m2 by the spraying method against Oncomelania snails was assessed in a setting with a high snail density in Husban Village, Jiangning District of Nanjing City, and the effect was compared with that of 50% wettable powder of niclosamide ethanolamine salt (WPN) at a dose of 2 gIm2 at different time after spraying.

RESULTS

Afterl, 3, 7 and 15 day (days) of the spraying experiment, the snail death rates of the TDS group were 56.47%, 57.32%, 90.58% and 93.41% respectively, while those of the WPN group were 49.22%, 53.37%, 95.92% and 97.26%, respectively. The differences between the rates of the 2 groups 1, 7, 15 day (days) after the spraying were statistically significant (all P < 0.05). Fifteen days after the spraying, the density of living snails reduced from 20.30 +/- 16.20 snails/0.1 m2 and 23.67 +/- 21.22 snails/0.1 m2 to 2.28 +/- 2.17 snails/0.1 m2 and 1.27 +/- 0.76 snailsl0.1 m2 in the TDS group and WPN group, respectively, with the reduction rates of 88.77% and 94.63%, respectively.

CONCLUSION

TDS can be used as an alternative molluscicide for the control of Oncornelania snails in hilly areas, which deserves further popularization.

[Field evaluation of a novel plant molluscicide "Luo-wei" against Oncomelania hupensis snails II molluscicidal effect in the field of lake areas in Hanchuan City, Hubei Province]

OBJECTIVE

To evaluate the effect of a novel plant molluscicide "Luo-wei" (Tea-seed distilled saponins, TDS) against Oncomelania hupensis in the field of lake areas in Hanchuan City, Hubei Province.

METHODS

Immersing experiment and spraying experiment were carried out in 5 ditches and a beach land respectively in Hanchuan City, Hubei Province to compare the molluscicidal effects among 4% TDS, 50% wettable powder of niclosamide ethanolamine salt (WPN), and 26% suspension concentrate of metaldehyde and niclosamide (MNSC) by different dosages and time. The chi2 test or Fish's exact test was used to examine the differences of snail death rates among them.

RESULTS

After 72 h of immersing experiment, the snail death rates in the 2.5 g/m3 TDS group, 3.0 g/m3 TDS group, 2.0 g/m3 WPN group and 2.0 g/m3 MNSC group were 99.33%, 100%, 100%, and 100%, respectively, and there was no significant difference among them (P > 0.05). By the end of 15 d after the spraying experiments, the snail death rates were 91.86% in the 2.0 g/m2 MNSC group, 90.26% in the 5.0 g/m2 TDS group, 87.45% in the 2 g/m2 WPN group, and 86.10% in the 3 g/m2 TDS group. The differences between the 5.0 g/m2 TDS group and 2.0 g/m2 MNSC group, as well as the 3.0 g/m2 TDS group and the 2.0 g/m2 WPN group had no statistical significance (both P > 0.05).

CONCLUSIONS

The molluscicidal effect of TDS is similar to that of WPN or MNSC. The recommended dosage of TDS is 2.5 g/m3 for immersing or 5 g/ m2 for spraying in the field.

Drug screening identifies niclosamide as an inhibitor of breast cancer stem-like cells

The primary cause of death from breast cancer is the progressive growth of tumors and resistance to conventional therapies. It is currently believed that recurrent cancer is repopulated according to a recently proposed cancer stem cell hypothesis. New therapeutic strategies that specifically target cancer stem-like cells may represent a new avenue of cancer therapy. We aimed to discover novel compounds that target breast cancer stem-like cells. We used a dye-exclusion method to isolate side population (SP) cancer cells and, subsequently, subjected these SP cells to a sphere formation assay to generate SP spheres (SPS) from breast cancer cell lines. Surface markers, stemness genes, and tumorigenicity were used to test stem properties. We performed a high-throughput drug screening using these SPS. The effects of candidate compounds were assessed in vitro and in vivo. We successfully generated breast cancer SPS with stem-like properties. These SPS were enriched for CD44^high (2.8-fold) and CD24^low (4-fold) cells. OCT4 and ABCG2 were overexpressed in SPS. Moreover, SPS grew tumors at a density of 10³, whereas an equivalent number of parental cells did not initiate tumor formation. A clinically approved drug, niclosamide, was identified from the LOPAC chemical library of 1,258 compounds. Niclosamide downregulated stem pathways, inhibited the formation of spheroids, and induced apoptosis in breast cancer SPS. Animal studies also confirmed this therapeutic effect. The results of this proof-of-principle study may facilitate the development of new breast cancer therapies in the near future. The extension of niclosamide clinical trials is warranted.

Inhibition of STAT3 by niclosamide synergizes with erlotinib against head and neck cancer

Epidermal growth factor receptor (EGFR) is extensively expressed in head and neck cancer. However, EGFR-targeted therapy has only modest efficacy in head and neck cancer, through mechanisms that are not fully understood. Here, we found that inhibition of EGFR by erlotinib stimulated phosphorylation and activation of STAT3 leading to increased Bcl2/Bcl-XL expression in head and neck cancer cells, which may dampen the therapeutic efficacy of erlotinib against head and neck cancer. Erlotinib-enhanced STAT3 phosphorylation results, at least in part, from suppression of its physiological phosphatase, PTPMeg2. Specific knockdown of STAT3 by RNA interference significantly sensitized head and neck cancer cells to erlotinib treatment. Pharmacological inhibition of STAT3 by niclosamide not only blocked erlotinib-stimulated STAT3 phosphorylation but also synergistically repressed head and neck cancer growth in vitro and in vivo. Combined inhibition of EGFR and STAT3 by erlotinib and niclosamide more effectively induced apoptosis in tumor tissues without toxicity for normal tissues. Based on our findings, treatment with erlotinib combined with niclosamide may offer an effective therapeutic approach to improve the prognosis of head and neck cancer.

Small molecule modulators of Wnt/β-catenin signaling

The Wnt signal transduction pathway is dysregulated in many highly prevalent diseases, including cancer. Unfortunately, drug discovery efforts have been hampered by the paucity of targets and drug-like lead molecules amenable to drug discovery. Recently, we reported the FDA-approved anthelmintic drug Niclosamide inhibits Wnt/β-catenin signaling by a unique mechanism, though the target responsible remains unknown. We interrogated the mechanism and structure-activity relationships to understand drivers of potency and to assist target identification efforts. We found inhibition of Wnt signaling by Niclosamide appears unique among the structurally-related anthelmintic agents tested and found the potency and functional response was dependent on small changes in the chemical structure of Niclosamide. Overall, these findings support efforts to identify the target of Niclosamide inhibition of Wnt/β-catenin signaling and the discovery of potent and selective modulators to treat human disease.

Niclosamide is a proton carrier and targets acidic endosomes with broad antiviral effects

Viruses use a limited set of host pathways for infection. These pathways represent bona fide antiviral targets with low likelihood of viral resistance. We identified the salicylanilide niclosamide as a broad range antiviral agent targeting acidified endosomes. Niclosamide is approved for human use against helminthic infections, and has anti-neoplastic and antiviral effects. Its mode of action is unknown. Here, we show that niclosamide, which is a weak lipophilic acid inhibited infection with pH-dependent human rhinoviruses (HRV) and influenza virus. Structure-activity studies showed that antiviral efficacy and endolysosomal pH neutralization co-tracked, and acidification of the extracellular medium bypassed the virus entry block. Niclosamide did not affect the vacuolar H(+)-ATPase, but neutralized coated vesicles or synthetic liposomes, indicating a proton carrier mode-of-action independent of any protein target. This report demonstrates that physico-chemical interference with host pathways has broad range antiviral effects, and provides a proof of concept for the development of host-directed antivirals.

[Distribution of niclosamide spreading oil on water surface and its efficacy against cercariae of Schistosoma japonicum]

OBJECTIVE

To investigate the distribution and spreading speed of niclosamide spreading oil, as well as its effect against cercariae of Schistosoma japonicum.

METHODS

The foamed plastic with a diameter of 4 mm served as a buoyage, which was placed at the center of the still water surface. The niclosamide spreading oil was dropped at 0.5 cm from the buoyage, the floating distance of the buoyage was observed, and the spreading speed and area of the niclosamide spreading oil were measured. A cylindrical bucket (at a diameter of 40 cm and height of 50 cm) was filled with de-chlorinated water at a temperature of 25 +/- 1 degrees C, and then 60 microl of the spreading oil was dropped at the center of the water surface. At 10 cm and 20 cm from the center, 1 ml water was sampled at water depths of 10, 20, 30, 40 cm and 50 cm, respectively, and the niclosamide concentrations were determined by using high-performance liquid chromatography in each sample. The niclosamide spreading oil was diluted into solutions at effective concentrations of 1.25 mg/L and 0.63 mg/L with ethanol, and then 10 microl of each solution was added to 24-well plates which contained S. japonicum cercariae to yield the niclosamide concentration of 6.25 x 10(-3) mg/L and 3.13 x 10(-3) mg/L per well, respectively. The survival of the cercariae was observed at different time.

RESULTS

The spreading speeds and areas were 59, 55, 71, 90, 111, 122 cm/s and 153 cm/s, and 5.31, 5.89, 7.07, 10.06, 12.56, 15.20 m2 and 16.61 m2, respectively, while dropping 20, 30, 40, 50, 60, 70 microl and 80 microl of the niclosamide spreading oil on water surface. The spreading showed an accelerating trend with the increasing dropping volume, and there was a good linear relationship observed between them. In addition, the spreading area also enlarged with the increase in the dropping volume. After dropping 60 microl of the niclosamide spreading oil on water surface, the peak concentration of niclosamide reached 1.27 mg/L on water surface, and remained more than 0.07 mg/L 2 h later. However, the concentration of niclosamide was all lower than 0.04 mg/L at 10 cm under surface or more. Following the treatment with 6.25 x 10(-3) mg/L of niclosamide spreading oil for 1 min, all the cercariae were dead, while the mortality rates of the cercariae were 0, 1.39%, 13.89%, 19.44%, 43.06%, 69.44% and 79.17% at 1, 2, 3, 5, 10, 20 min and 30 min, respectively, after the treatment with 3.13 x 10(-3) mg/L of the drug.

CONCLUSIONS

The niclosamide spreading oil is fast to spread and is kept retention for a long time on water surface, and exhibits high activity against S. japonicum cercariae, and it can be used for killing the cercariae on water surface and interrupting the transmission of schistosomiasis in the endemic field.

[Effect of niclosamide spreading oil on killing schistosome cercariae]

Dechlorinated water (100 ml, 30 degrees C) was put into a plate (diameter 15 cm), and 1% niclosamide spreading oil 5 microl was added, then a ring of Schistosoma japonicum cercariae were picked up to the plate. The time of killing all the cercariae was observed at three time points (immediately, 24, 48 h), and the dechlorinated water was used as control. The results showed that schistosome cercariae were all killed in three minutes by 1% niclosamide spreading oil at the three time points. The cercaria-killing effects of each time point were not significantly different (F = 0.062, P > 0.05). The cercariae were alive in the control in 48 h.

[Effect of snail control of niclosamide by soil mixing and spraying methods in high dam of terrace]

The snail control efffect of niclosamide by soil mixing and spraying method were compared, and the results showed that the effects of the two methods were similar. Though there was difficulties in getting soil and mixing durg with soil, and the cost was high, the effect of soil mixing method in some special environment such as stone ditches and terraces.

[Studies on standardization of methods for screening molluscicides in laboratory IV sensitivity of Oncomelania snails from different months to niclosamide]

OBJECTIVE

To understand the sensitivity of Oncomelania snails collected from different months to niclosamide, so as to provide the scientific evidence for the standardization of methods for molluscicide screening and efficacy evaluation in laboratory.

METHODS

The snails collected from the marshland of Zhenjiang City, Jiangsu Province month by month from June 2010 to May 2011. After being raised in laboratory for 24 h, the snails were randomly grouped, and then immersed in different concentrations of 50% wettable powder formulation of niclosamide ethanolamine salt at (25 +/- 1) degrees C with a humidity of 60%. The dead snails were identified and counted, and the mortality rate of snails and median lethal concentration (LC50) were calculated.

RESULTS

When the snails were immersed in the solutions of niclosamide at concentrations of more than 0.5 mg/L for 24 h, all the snails collected from different months were dead, while 60%-100% of the snail mortality was achieved for 0.250 mg/L niclosamide, 3%-27% for 0.125 mg/L niclosamide, and 3%-20% for 0.062 5 mg/L niclosamide. When the concentration was lower than 0.032 mg/L, the niclosamide was not toxic to the snails within 24 h. The LC50 value was 0.140-0.209 mg/L for 24 h. When the snails were immersed in the solutions of niclosamide at concentrations of more than 0.5 mg/L for 48 h, all the snails collected from different months were dead, while 90%-100% of the snail mortality was achieved for 0.250 mg/L niclosamide, 3%-57% for 0.125 mg/L niclosamide, 3%-13% for 0.062 5 mg/L niclosamide, and 0-10% for 0.032 mg/L niclosamide. When the concentration was lower than 0.016 mg/L, the niclosamide was not toxic to the snails within 48 h. The LC50 value was 0.112-0.170 mg/L for 48 h. There were no significant differences in the mortality of snails caused by niclosamide treatment observed at 24 and 48 h (P values = 0.374 and 0.267, respectively).

CONCLUSIONS

There are little changes in the sensitivity of snails collected from different months to niclosamide, with minor fluctuations in LC50 values. Such a finding indicates that the snails collected from different months have few effects on screening of molluscicides and efficacy evaluation.

Niclosamide suppresses cancer cell growth by inducing Wnt co-receptor LRP6 degradation and inhibiting the Wnt/β-catenin pathway

The Wnt/β-catenin signaling pathway is important for tumor initiation and progression. The low density lipoprotein receptor-related protein-6 (LRP6) is an essential Wnt co-receptor for Wnt/β-catenin signaling and represents a promising anticancer target. Recently, the antihelminthic drug, niclosamide was found to inhibit Wnt/β-catenin signaling, although the mechanism was not well defined. We found that niclosamide was able to suppress LRP6 expression and phosphorylation, block Wnt3A-induced β-catenin accumulation, and inhibit Wnt/β-catenin signaling in HEK293 cells. Furthermore, the inhibitory effects of niclosamide on LRP6 expression/phosphorylation and Wnt/β-catenin signaling were conformed in human prostate PC-3 and DU145 and breast MDA-MB-231 and T-47D cancer cells. Moreover, we showed that the mechanism by which niclosamide suppressed LRP6 resulted from increased degradation as evident by a shorter half-life. Finally, we demonstrated that niclosamide was able to induce cancer cell apoptosis, and displayed excellent anticancer activity with IC₅₀ values less than 1 µM for prostate PC-3 and DU145 and breast MDA-MB-231 and T-47D cancer cells. The IC₅₀ values are comparable to those shown to suppress the activities of Wnt/β-catenin signaling in prostate and breast cancer cells. Our data indicate that niclosamide is a unique small molecule Wnt/β-catenin signaling inhibitor targeting the Wnt co-receptor LRP6 on the cell surface, and that niclosamide has a potential to be developed a novel chemopreventive or therapeutic agent for human prostate and breast cancer.

[Snail control effect of film covering method in fish ponds and ditches]

OBJECTIVE

To evaluate the snail control effect of a film covering method in fish ponds and ditches.

METHODS

Two fish ponds and 2 ditches with Oncomelania snails were selected as pilots, and 1 fish pond as Group A1 and I ditch as Group B1 received niclosamide spraying + film covering, and another fish pond as Group A2 and another ditch as Group B2 received niclosamide spraying only. The snail control effects were observed at 15, 30, 90 d and 360 d after the test, and the fish and other aquatic were also observed.

RESULTS

In Group A1, the adjusted mortality rates of snails were 92.31%, 99.36% and 100% at 15, 30 d and 90 d after the test, respectively; in Group B1, the adjusted mortality rates of snails were 91.45%, 95.84% and 100% at 15, 30 d and 90 d after the test, respectively; and there was no death of fish. The densities of snails were 0 and 0.07 snails/0.1 m2 one year after the test, respectively. In Group A2, the adjusted mortality rates of snails were 75.36%, 72.59% and 65.76% at 15 d, 30 d and 90 d after the test, respectively; in Group B2, the adjusted mortality rates of snails were 70.36%, 72.87% and 75.82% at 15, 30 d and 90 d after the test, respectively; and there was death of fish. The densities of snails were 0.11 snails/0.1 m2 and 0.13 snails/0.1 m2 one year after the test, respectively.

CONCLUSION

In ponds and ditches with snails, the niclosamide spraying + film covering method is very effective and safe.

[Surveillance and forecast system of schistosomiasis in Jiangsu Province. IV. Establishment of Schistosoma japonicum cercaria-killing method by spraying niclosamide suspension on water surface]

OBJECTIVE

To investigate the effect of suspension concentrate of niclosamide (SCN) on killing cercariae of Schistosoma japonicum on water surface, optimization and impact on fish, so as to establish an emergency-treatment intervention for rapidly killing cercariae and eliminating water infectivity.

METHODS

SCN was formulated into different concentrations of solutions, and then the solutions were sprayed on the surface of water containing S. japonicum cercariae. The water infectivity was determined by using mice at 0, 10, 30 min after spraying SCN. SCN was formulated into a solution of 100 mg/L and then sprayed on the surface of the water by using the spraying values of 0.01, 0.02, 0.03 g/m2 and 0.04 g/m2. At 30 min and 60 min after spraying, the water infectivity was determined by using mice. Zebra fish were transferred into the static water, then 100 mg/L SCN (s), using spraying values of 0.01, 0.02, 0.03 g/m2 and 0.04 g/m2, were sprayed on water surface. At 0, 10, 30, 60 min after spraying, the samples were collected at water depths of 0, 10, 20, 30, 40 cm, and niclosamide was determined by using high-performance liquid chromatography. The death of zebra fish was continually observed within 96 h after spraying SCN.

RESULTS

At 0, 10, 30 min after spraying 1 000, 100, 10, 1, 0.1 mg/L SCN on water surface, the infectivity of water significantly decreased. At 30 min after spraying 1 000 mg/L and 100 mg/L SCN, no schistosome infectivity was detected in the water. At 30 min after spraying 100 mg/L SCN, with spraying values of 0.01, 0.02, 0.03, 0.04 g/m2, the water infectivity significantly reduced, and no infectivity was found 60 min after spraying SCN. After the surface of static water was sprayed with 100 mg/L SCN, the peak concentration was found at 0 min, and the solution diffused to site with a water depth of 10 cm after 10 min, and 30 min later, SCN diffused to the whole water body, and distributed evenly. After spraying 100 mg/L SCN on the surface of water with a volume of (3.14 x 20(2) x 50) cm3, by using the spraying value of 0.02 g/m2, 96 h later, no death of zebra fish was found.

CONCLUSIONS

From 30 to 60 min after spraying 100 mg/L SCN, with the value of 0.02 g/m2, on the surface of S. japonicum-infested water, the water infectivity can be eliminated, and there is no evident toxicity to fish. This cercaria-killing method, as an emergency-treatment intervention for infested water, can be applied in those surveillance and forecast sites.

Niclosamide prevents the formation of large ubiquitin-containing aggregates caused by proteasome inhibition

Background

Protein aggregation is a hallmark of many neurodegenerative diseases and has been linked to the failure to degrade misfolded and damaged proteins. In the cell, aberrant proteins are degraded by the ubiquitin proteasome system that mainly targets short-lived proteins, or by the lysosomes that mostly clear long-lived and poorly soluble proteins. Both systems are interconnected and, in some instances, autophagy can redirect proteasome substrates to the lysosomes.

Principal Findings

To better understand the interplay between these two systems, we established a neuroblastoma cell population stably expressing the GFP-ubiquitin fusion protein. We show that inhibition of the proteasome leads to the formation of large ubiquitin-containing inclusions accompanied by lower solubility of the ubiquitin conjugates. Strikingly, the formation of the ubiquitin-containing aggregates does not require ectopic expression of disease-specific proteins. Moreover, formation of these focused inclusions caused by proteasome inhibition requires the lysine 63 (K63) of ubiquitin. We then assessed selected compounds that stimulate autophagy and found that the antihelmintic chemical niclosamide prevents large aggregate formation induced by proteasome inhibition, while the prototypical mTORC1 inhibitor rapamycin had no apparent effect. Niclosamide also precludes the accumulation of poly-ubiquitinated proteins and of p62 upon proteasome inhibition. Moreover, niclosamide induces a change in lysosome distribution in the cell that, in the absence of proteasome activity, may favor the uptake into lysosomes of ubiquitinated proteins before they form large aggregates.

Conclusions

Our results indicate that proteasome inhibition provokes the formation of large ubiquitin containing aggregates in tissue culture cells, even in the absence of disease specific proteins. Furthermore our study suggests that the autophagy-inducing compound niclosamide may promote the selective clearance of ubiquitinated proteins in the absence of proteasome activity.

Cyanolide A, a glycosidic macrolide with potent Molluscicidal activity from the Papua New Guinea cyanobacterium Lyngbya bouillonii

Over the last 50 years, molluscicides have played a critical role in the control of schistosomiasis transmission. Cyanolide A (2), isolated from extracts of a Papua New Guinea collection of Lyngbya bouillonii, is a new and highly potent molluscicidal agent against the snail vector Biomphalaria glabrata (LC(50) = 1.2 microM). The structure of cyanolide A (2) was elucidated through extensive NMR spectroscopic analyses, yielding a symmetrical dimer that represents the newest addition to the family of glycosidic macrolides from cyanobacteria.

A novel method for oral delivery of apolipoprotein mimetic peptides synthesized from all L-amino acids

Administered subcutaneously, D-4F or L-4F are equally efficacious, but only D-4F is orally efficacious because of digestion of L-4F by gut proteases. Orally administering niclosamide (a chlorinated salicylanilide used as a molluscicide, antihelminthic, and lampricide) in temporal proximity to oral L-4F (but not niclosamide alone) in apoE null mice resulted in significant improvement (P < 0.001) in the HDL-inflammatory index (HII), which measures the ability of HDL to inhibit LDL-induced monocyte chemotactic activity in endothelial cell cultures. Oral administration of L-[113-122]apoJ with niclosamide also resulted in significant improvement (P < 0.001) in HII. Oral administration of niclosamide and L-4F together with pravastatin to female apoE null mice at 9.5 months of age for six months significantly reduced aortic sinus lesion area (P = 0.02), en face lesion area (P = 0.033), and macrophage lesion area (P = 0.02) compared with pretreatment, indicating lesion regression. In contrast, lesions were significantly larger in mice receiving only niclosamide and pravastatin or L-4F and pravastatin (P < 0.001). In vitro niclosamide and L-4F tightly associated rendering the peptide resistant to trypsin digestion. Niclosamide itself did not inhibit trypsin activity. The combination of niclosamide with apolipoprotein mimetic peptides appears to be a promising method for oral delivery of these peptides.

[Molluscicidal effect and toxicity of META-Li on Oncomelania snails in the mountain area]

The molluscicidal effect and toxicity of META-Li were evaluated and compared with niclosamide in Yushan county of Jiangxi Province in August 2008. There are four groups named as META-Li ridge group (1 g/m2), META-Li field group (1 g/m2), niclosamide group (2 g/m2) and control group. At 3 d, 7 d, 15 d and 2 months after drugs sprayed, the corrected mortalities of snails in the 3 groups were considerably higher than those of control (P<0.05). The corrected mortalities in META-Li field group were significantly lower than those of META-Li ridge group and niclosamide group (P<0.05). No adverse effect was observed to non-target organisms in META-Li groups, while fishes, snails and frogs all died at the first day after treated with niclosamide.

Efficacy of temperature, and two commonly used molluscicides and fertilizers on Fasciola gigantica eggs

This study evaluated the effect of temperature, molluscicides (Copper sulphate and Niclosamide), fertilizers (Superphosphate and Ammonium sulphate) on the hatchability of Fasciola gigantica eggs. The results showed that hatchability decreased to 4% when eggs were incubated in bile secretion at 37 degrees C for 5 days and to 1.4% for 10 days, but few eggs incubated in water at 37 degrees C hatched. Bile secretion at 37 degrees C was a poor medium for in-vitro egg preservation. But, hatching occurred only when eggs were transferred to water at 26 degrees C. Temperature fluctuation from 26-4 degrees C or from 32-4 degrees C had an inhibitory effect on embryos development (35.2% & 32.3%, respectively) as compared to controls (60% & 63.9%, respectively). The incubation period (19 & 17 days) was higher than controls (14 & 12 days, respectively). The LC50 & LC90 of Copper sulphate and Niclosamide against Biomphalaria alexandrina and Lymnaea natalenesis had no toxic effect on Fasciola eggs. The higher concentrations of Copper sulphate (30 ppm) and Niclosamide (1 ppm) slightly lower eggs hatchability rate than controls. The rate decreased by increasing the exposure time from 3 to 6 hours with both molluscicides. Ammonium sulphate had a lethal effect on eggs, but Superphosphate had some inhibitory effect on egg development, which increased by increasing Superphosphate concentration or with the prolongation of the exposure time.

In vitro trypanocidal activity of the anti-helminthic drug niclosamide

Only a few drugs are available for chemotherapy of African trypanosomiasis and there is an urgent need for the development of new anti-trypanosomal agents. In this study, the anti-helminthic drug niclosamide was tested for its trypanocidal activity in vitro using culture-adapted bloodstream forms of Trypanosoma brucei brucei and Trypanosoma congolense. The concentrations of niclosamide to reduce the growth rate by 50% and to kill all cells were in the low- and mid micromolar ranges for T. b. brucei and T. congolense, respectively. The very low toxicity of niclosamide for mammals makes the compound interesting for drug development for African trypanosomiasis.

[Study on molluscicidal effect of chlorosalicylicamide]

OBJECTIVE

To observe the molluscicidal effect of chlorosalicylicamide on Oncomelania hupensis and toxicity on fishes.

METHODS

Different concentrations of chlorosalicylicamide were prepared, and immersion and spraying methods were used to test its molluscicidal effect and toxicity to fishes. Niclosamide ethanolamine salt was used as control.

RESULTS

Under water temperature of 28 C with the dose of chlorosalicylicamide at 0.25 mg/L and 0.4 mg/L, the mortality rate of snails by immersion was 97.8% and 100% respectively after 48 h, and the LC50 was 0.0674 mg/L. While for niclosamide at the same doses, the mortality rate of snails was 22.2% and 66.7% respectively, and the LC50 was 0.397 6 mg/L. With the concentration of 0.4 mg/L for 72 h, the fish death rate in chlorosalicylicamide and niclosamide was 50.0% and 100% respectively.

CONCLUSION

Chlorosalicylicamide shows a molluscicidal effect on Oncomelania snails and a lower toxicity to fishes than that of niclosamide.

A studies on chemical control of S. mansoni intermediate host

This study was conducted to screen different snail species to determine their susceptibility for different parasitic infections and also to determine LC50 and LC90 values. The screening of snail species infected with Schistosome parasite and mean number of cercariae shed by individual infected snail was 184+12. The experiment on relationship of snail size and dose of Niclosamide showed that juvenile snails were more susceptible to chemical when compared with adult snails. A series of seven experiments indicated that concentration of 0.067 and 0.109 mg L(-1) were required to kill 50 and 90% snails, respectively in an exposure period of 24 h and no death occurred in recovery period.

Effect of niclosamide on the tegumental surface of Haplorchis taichui using scanning electron microscopy

The effect of niclosamide on the tegument of adult Haplorchis taichui (Trematoda: Heterophyidae) exposed in vitro was observed by scanning electron microscope. Adult worms were incubated in Tyrode's solution containing 0.01, 0.1, 1.0, and 10 microg ml(-1) of niclosamide for 30 min, 1, 6, 12 and 24 h. Control groups were incubated in Tyrode's solution without niclosamide and worms remained active until 24 h. In 0.01 microg ml(-1) of niclosamide, worms showed slightly active movements up to 1 h after incubation, while in 0.1 microg ml(-1) solution a few worms showed only slightly active movements after 30 min. Tegumental changes were determined by scanning electron microscopy. Swelling and blebbing of the tegument were observed on both ventral and dorsal sides. After longer periods, extensive swelling and blebbing of the tegument became more severe and there was a loss of the apical plasma membrane in some regions. Empty spine sockets occurred, and small perforations penetrated the basal lamina, followed by some lesions. Destruction of both surfaces was more pronounced on the posterior compared with the anterior regions.

[Synergic effects of synthesis arecoline in combination with snail-killing drugs niclosamide]

OBJECTIVE

To prove that synthetic Are combination with snail-killing drug Nic can increase the effects of snail-killing remarkably.

METHODS

In indoor immersing experimentation, the experiments were divided into 4 groups, 30 snails in each group, to observe the rate of opening operculum, the rate of climbing adhesion and the rate of death at 3, 6 and 24 hours respectively. In field experimentation, we intermixed 0.1 mg/L Are with 0.2 mg/L Nic as sample as contrasted with 2 mg/L Nic and non-drug group. Immersing method (we chose three slots each size were 10 m x 2 m x 1 m.) and insufflation method (we chose three patch of bottomlands each area were 10 m x 5 m.) were used to kill snails separately and the death rate of fish, at the same time was observed.

RESULTS

In the room, as we added 0.1 mg/L Are to the solution of 0.1 mg/L and 0.2 mg/L Nic separately, the opening operculum rate for 6 hours was increased from 20% and 12% to 100% and 95%, the climbing adhesion rate for 6 hours decreased from 17% and 53% to 3% and 5%, the death rate for 24 hours increased from 25% and 40% to 90% and 100%. In the field, the snails death rate in sample group and in contrastive group applied with immersing method and insufflation method for 72 hours were 95.9%, 93.3% and 100%, 95.8%; only one small fish (2 cm long) died in sample group, and all fishes died in Nic group, and all fish were alive in non-drug group.

CONCLUSION

It proved that synthetic Are combination with snail-killing drug Nic might decrease Nic dosage and toxicity and increase the effects of snail-killing.

Field trials of low dose Bayluscide on snail hosts of schistosome and selected non-target organisms in sahelian Cameroon

More than 85% of all cases of schistosomiasis in Cameroon occur in the northern sahelian half of the country representing 20% of the population. Several workers have advocated the integrated approach to schistosomiasis control, including snail control, but the death and decay of aquatic organisms, and fish kill that often follows Bayluscide application at the dose of 1 g/m3 decrease its acceptability. The present study was designed to assess the effect of lower Bayluscide doses on snail host and non-target fish, frog, the tadpole kill. Bayluscide was applied to study ponds at concentrations of 0, 0.25, 0.5, and 1 g/m3 (ppm). Pre and post application assessment of snails hosts of schistosomes, fish, frog, and tadpole kill were carried out. All 0.25, 0.5, and 1 g/m3 Bayluscide concentrations reduced snail population significantly. Bayluscide concentration of 0.50 g/m3 applied in two rounds of 0.25 g/m3 resulted in high snail mortality and low lethality to fish, frogs, and tadpoles. Further studies are needed to assess the cost-effectiveness of Bayluscide in the control of schistosomiasis following the simplified approach.

Impact of certain plants and synthetic molluscicides on some fresh water snails and fish

The LC50 (78, 85 ppm) and LC90 (88, 135 ppm) of Anagalis arvensis and Calendula micrantha respectively against Biomphalaria alexandrina were higher than those of the non-target snails, Physa acuta, Planorbis planorbis, Helisoma duryi and Melanoides tuberculata. In contrast, the LC50 of Niclosamide (0.11 ppm) and Copper sulphate (CuSO4) (0.42 ppm) against B. alexandrina were lower than those of the non-target snails. The mortalities percentage among non-target snails ranged between 0.0 & 20% when sublethal concentrations of CuSO4 against B. alexandrina mixed with those of C. micrantha and between 0.0 & 40% when mixed with A. arvensis. Mortalities ranged between 0.0 & 50% when Niclosamide was mixed with each of A. arvensis and C. micrantha. A. arvensis induced 100% mortality on Oreochromis niloticus after 48 hrs exposure and after 24 hrs for Gambusia affinis. C. micrantha was non-toxic to the fish. The survival rate of O. niloticus and G. affinis after 48 hrs exposure to 0.11 ppm of Niclosamide were 83.3% & 100% respectively. These rates were 91.7% & 93.3% respectively when each of the two fish species was exposed to 0.42 ppm of CuSO4. Mixture of sub-lethal concentrations of A. arvensis against B. alexandrina and those of Niclosamide or CuSO4 at ratios 10:40 & 25:25 induced 66.6% mortalities on O. niloticus and 83.3% at 40:10. These mixtures caused 100% mortalities on G. affinis at all ratios. A. arvensis CuSO4 mixtures at 10:40 induced 83.3% & 40% mortalities on O. niloticus and G. affinis respectively and 100% mortalities on both fish species at ratios 25:25 & 40:10. A mixture of sub-lethal concentrations of C. micrantha against B. alexandrina and of Niclosamide or CuSO4 caused mortalities of O. niloticus between 0.0 & 33.3% and between 5% & 35% of G. affinis. The residue of Cu in O. niloticus were 4.69, 19.06 & 25.37 mg/1kgm fish after 24, 48 & 72 hrs exposure to LC0 of CuSO4 against B. alexandrina respectively.

Transport of Schistosoma japonicum cercariae and the feasibility of niclosamide for cercariae control

Field experiments were conducted in southwestern China to estimate the distances over which cercariae of Schistosoma japonicum are transported and remain infective in village irrigation ditches and to determine the feasibility of interrupting this transport using niclosamide, the molluscicide commonly used for snail control in this environment. The number of worms recovered from bioassay mice downstream from experimentally introduced cercariae, but without niclosamide, decreased about 90% over the first 100 m of ditch and then remained essentially constant for the remaining 300 m of the ditch that was monitored. The niclosamide experiments resulted first in the finding that it was possible to achieve ditch average concentrations close to the target values of 0.25 ppm, but that concentrations at any particular location varied by a factor of up to 3. There was no correlation between water turbidity and niclosamide concentration. An average water concentration of 0.29 ppm resulted in no viable cercariae after a contact time of about 1 min and a travel distance of only 10 m. We regard these results as proof of the feasibility of chemical interruption of transport of S. japonicum cercariae although the toxicity of niclosamide to fish at the levels used here make it a questionable candidate for routine use.

Inhibition of severe acute respiratory syndrome coronavirus replication by niclosamide

Antiviral agents are urgently needed to fight severe acute respiratory syndrome (SARS). We showed that niclosamide, an existing antihelminthic drug, was able to inhibit replication of a newly discovered coronavirus, SARS-CoV; viral antigen synthesis was totally abolished at a niclosamide concentration of 1.56 microM, as revealed by immunoblot analysis. Thus, niclosamide represents a promising drug candidate for the effective treatment of SARS-CoV infection.

The Hymenolepis diminuta–Golden Hamster (Mesocricetus auratus) Model for the Evaluation of Gastrointestinal Anticestode Activity

A novel laboratory anticestode assay was developed using Hymenolepis diminuta in the hamster. The commercial anticestode compounds, praziquantel, bunamidine, and niclosamide were active against patent infections of Hymenolepis diminuta in golden hamsters (Mesocricetus auratus) when given orally at 3.125, 100, and 200 mg/kg, respectively. The gastrointestinal nematode anthelmintics, cambendazole and mebendazole, were active at 50 mg/kg. Rafoxanide (fasciolicide) was active at 25 mg/kg, the lowest level tested. The coccidiostat, nicarbazin, was active at experimental levels (800 mg/kg and up). The anthelmintic-ectoparasiticide (endectocide), ivermectin, was inactive against the tapeworm at 0.5 mg/kg, as expected.

[Sensitivity of Oncomelania snail to niclosamide in China]

OBJECTIVE

To understand the variation in response of Oncomelania hupensis to niclosamide.

METHODS

Snails were collected from 37 sampling areas distributed in 10 provinces (municipalities) using random environmental sampling methods in accordance with the different types and categories of snail habitats. In laboratory the snails were immersed in solutions of niclosamide for 24 and 48 hours at 25 degrees C.

RESULTS

1.0 mg/L niclosamide showed 100% killing effect on snails in 24 hours. The LC50 concentrations for snails immersed for 24 hours ranged from 0.0320 to 0.1689 mg/L with a mean value of 0.0920 mg/L. 0.5 mg/L niclosamide showed 100% killing effect on snails in 48 hours. The LC50 values for snails immersed for 48 hours ranged between 0.0299 and 0.1114 mg/L with a mean of 0.0627 mg/L. There is a significant difference in snail sensitivity to niclosamide between sampling areas.

CONCLUSION

The sensitivity to niclosamide varied in snails from different sampling fields, but the chemical in a concentration of 1.0 mg/L showed 100% effect of killing snails, which is consistent to the manual of schistosomiasis control.

Measures for the prevention and control of Taenia solium taeniosis and cysticercosis

Taeniosis and cysticercosis due to Taenia solium are public health problems in many developing countries. Many studies of this parasitic zoonosis have focused on clinical features, diagnosis, treatment, surveillance, epidemiology and risk factors analysis. More recently projects on community and mass intervention strategies had been conducted in several rural areas worldwide focused on pig vaccination, pig cysticercosis treatment, human mass treatment, infrastructure development, as well as health education campaigns. Their advantages, disadvantages and public health impact have been published. This document discusses the feasibility and limitations of these interventions in order to assist countries in selection the best strategy for the prevention and control of this disease; we emphasized the specific strategies that might be recommended in different demographical situations.

[Climbing-upward inhibition of Oncomelania hupensis by niclosamide combination]

OBJECTIVE

To develop a combination of molluscicide/insecticide with a good molluscicidal effect, especially an inhibitory effect on climbing-upward of Oncomelania hupensis.

METHODS

Experiments on molluscicidal and snail-climbing inhibition effect of the combination of niclosamide and shachongding [(dimethylamine) trithacyclohexane hydrochloride] were conducted by immersion and spraying in laboratory.

RESULTS

The combination of niclosamide (0.2 mg/L) and shachongding (0.1 mg/L) showed an inhibition of 92.67% of snails to climb up. There was no significant difference in molluscicidal effect between the combination (LC90 0.198 mg/L) and niclosamide alone (LC90 0.207 mg/L).

CONCLUSION

The combination showed an effective inhibition on the climbing-upward of snails in water so as to improve the molluscicidal effect and reduce the cost of mollusciciding.

Evaluation of different means of control of snail intermediate host of Schistosoma mansoni

Four water courses having the same conditions and snail density were chosen for this study. All methods were applied simultaneously in April. Snails were collected monthly to evaluate the malacological effect. A single application of 100 ppm dried A. maritima decreased the snail density significantly within one month. Snail density was maintained very low until the end of the year. Fresh Azolla pinnata applied in a dose of 280 ppm lowered snail density to a level intermediate between Ambrosia maritima and Bayluscide. Snail population began to build 5 months later. Bayluscide applied once at a dose of 1 ppm lowered significantly the snail density. This lowering was maintained for 4 months after which snails began to build up and remained high until the end of the study period. Clearing of vegetations was followed by abrupt lowering of snail density which was maintained for a period longer than that following Bayluscide and Azolla.

The effects of clofazimine, niclosamide & amphotericin B, on electron transport of Leishmania donovani promastigotes

BACKGROUND & OBJECTIVES

The study was undertaken to explore the locus of interaction of clofazimine and niclosamide which showed substantial growth inhibition property in Leishmania donovani promastigotes.

METHODS

The uptake of final electron acceptor oxygen and 2,6-dichlorophenolindophenol (DCPIP) reduction in the electron transport chain were measured by constant volume Warburg respirometer and monitoring absorbance at 600 nm, respectively. Irreversibility of O2 uptake inhibition by clofazimine and niclosamide was determined by dilution of cell suspension followed by centrifugation.

RESULTS

Clofazimine and niclosamide showed their minimum inhibitory concentration (MIC) at 33 and 150 micrograms/ml, respectively. Oxygen uptake inhibition by clofazimine and niclosamide was not reversed by removal of the drug by centrifugation. Rotenone, a potent inhibitor of mammalian electron transport chain showed no inhibition on the electron transport chain of L. donovani promastigotes. Cyanide at 1 mM concentration showed partial inhibition in L. donovani promastigotes. Oxygen uptake and DCPIP reduction by L. donovani promastigotes were highly sensitive to sulphhydryl group inhibitors. Strong inhibition of oxygen uptake (80-100%) by L. donovani promastigotes was achieved by clofazimine, niclosamide and amphotericin B. Amphotericin B failed to inhibit DCPIP reduction by L. donovani promastigotes, whereas DCPIP reduction was inhibited by clofazimine and niclosamide, respectively.

INTERPRETATION & CONCLUSION

DCPIP reduction was mediated by transplasma membrane electron transport as evidenced by its inhibition with membrane impermeable quinone 1,2-naphthoquinone-4-sulphonic acid (NQSA). Transplasma membrane electron transport requires b-cytochromes and sulphhydryl groups for its function and was inhibited by clofazimine and niclosamide.