Amodiaquine Resistance in Plasmodium falciparum Malaria in Afghanistan Is Associated with the pfcrt SVMNT Allele at Codons 72 to 76

Mutations in the Plasmodium falciparum genes pfcrt and pfmdr1 are selected by amodiaquine treatment in Africa. To examine the importance of these mutations in amodiaquine-treated Asian parasites, we determined pre- and posttreatment genotypes for amodiaquine treatment failures from a clinical trial in Afghanistan. The pfcrt codon 72 to 76 haplotype SVMNT was present in all samples tested, both before and after treatment. Amodiaquine did not clearly select for any pfmdr1 genotype, but a novel mutation, pfmdr1 N86F, was detected in four samples. We provide in vivo data to support the in vitro correlation between pfcrt SVMNT and increased resistance to the metabolite of amodiaquine.Amodiaquine (AQ), a 4-aminoquinoline related to chloroquine (CQ), has been used commonly as a monotherapy and now as a partner drug in artemisinin-based combination therapies (ACTs) for the treatment of uncomplicated Plasmodium falciparum malaria. In many countries, predominantly in Africa, the in vivo efficacy of AQ was found to be good even in the face of increasing CQ resistance (12). However, reports of AQ resistance have come from South America, Asia, and East Africa (7, 8, 10).Mutations in the P. falciparum chloroquine resistance transporter gene (pfcrt) and multidrug resistance gene 1 (pfmdr1) have been associated with clinical resistance to both CQ and AQ (13). The presence of the pfcrt codon 72 to 76 haplotype SVMNT (Ser-Val-Met-Asn-Thr) correlates with high-level resistance to the AQ metabolite desethylamodiaquine (DEAQ) in in vitro tests (14) and has been detected with a high prevalence in parasite populations from Brazil, Papua New Guinea, Laos, Iran, and India (9, 18). Clinical trials in East Africa have also demonstrated high levels of in vivo resistance to AQ; in those studies, the parasites carried pfcrt codon 72 to 76 haplotype CVIET, and pfmdr1 polymorphisms 86Y, 184Y, and 1246Y were found to be selected after AQ treatment failure (5, 6, 11).A clinical trial performed in Nangahar Province, East Afghanistan, in 2002 and 2003 to explore possible replacement treatments for CQ showed very poor efficacies of both CQ and AQ monotherapy (adequate clinical and parasitological responses were seen in 11% and 9% of cases, respectively, by day 42) (4). Our aim in this study was to evaluate pre- and posttreatment samples from patients treated with AQ for pfcrt and pfmdr1 mutations and to determine which, if any, polymorphisms are associated with AQ treatment failure in Afghanistan.     

Intermediate band solar cell materials through the doping of group-VA elements (N,P, As and Sb) in Cu2ZnSiSe4

The electronic structure and optical properties of group-VA (N, P, As, and Sb)-doped Cu₂ZnSiSe₄ alloys have been studied using a hybrid functional through density functional theory calculations. The minor lattice distortion and small formation energy indicate that synthesis of these alloys is highly possible in experiment. For each doped alloy, an isolated and partially filled intermediate band (IB) appears in its band structure. The doping-induced IB is mainly contributed by the s states of the doped group-VA atom and the p states of four neighboring Se atoms, and slightly by the d states of eight Cu atoms. The existence of an IB obviously enhances the absorption coefficient with two additional absorption peaks in the visible light range. For P, As and Sb-doped Cu₂ZnSiSe₄ alloys, not only the bandgap between the valence band maximum and the conduction band minimum but also the sub bandgap between the valence band maximum and the IB are very close to the optimal values for visible light absorption. Therefore, these alloys are recommended as good candidates for IB solar cell materials.

The doping of group-VA elements in Cu₂ZnSiSe₄ induces an intermediate band and enhances the absorption coefficient with two additional peaks.     

Anti-inflammatory and cytoprotective effects of selected Pakistani medicinal plants in Helicobacter pylori-infected gastric epithelial cells

Ethnopharmacological relevance

Helicobacter pylori infection is associated with gastritis, peptic ulcer, and gastric cancer. Due to its high global prevalence and uprising resistance to available antibiotics, efforts are now directed to identify alternative source to treat and prevent associated disorders. In the present study, effect of selected indigenous medicinal plants of Pakistan was evaluated on the secretion of interleukin-8 (IL-8) and generation of reactive oxygen species (ROS) in a bid to rationalize their medicinal use and to examine the anti-inflammatory and cytoprotective effects in gastric epithelial cells.

Materials and methods

AGS cells and clinically isolated Helicobacter pylori strain (193C) were employed for co-culture experiments. Anti-Helicobacter pylori activity and cytotoxic effects of the selected plants were determined by serial dilution method and DNA fragmentation assay respectively. ELISA and flow cytometry were performed to evaluate the effect on IL-8 secretion and ROS generation in Helicobacter pylori-infected cells.

Results

At 100 μg/ml, extracts of Alpinia galangal, Cinnamomum cassia, Cinnamomum tamala, Mentha arvensis, Myrtus communis, Oligochaeta ramose, Polygonum bistorta, Rosa damascena, Ruta graveolens, Syzygium aromaticum, Tamarix dioica, and Terminalia chebula exhibited strong inhibitory activity against IL-8 secretion. Of these, four extracts of Cinnamomum cassia, Myrtus communis, Syzygium aromaticum, and Terminalia chebula markedly inhibited IL-8 secretion at both 50 and 100 μg/ml. Cinnamomum cassia was further assessed at different concentrations against Helicobacter pylori and TNF-α stimulated IL-8 secretion, which displayed significant suppression of IL-8 in a concentration-dependent-manner. Among the plants examined against ROS generation, Achillea millefolium, Berberis aristata, Coriandrum sativum, Foeniculum vulgare, Matricaria chamomilla and Prunus domestica demonstrated significant suppression of ROS from Helicobacter pylori-infected cells (p < 0.01).

Conclusion

Results of the study revealed anti-inflammatory and cytoprotective effects of selected medicinal plants which could partially validate the traditional use of these plants in GI disorders particularly associated with Helicobacter pylori. Furthermore, results obtained may lead to possible future candidates of chemoprevention against peptic ulcer or gastric cancer.     

Randomized controlled trials of 5- and 14-days primaquine therapy against relapses of vivax malaria in an Afghan refugee settlement in Pakistan

Primaquine is the only drug available that can eliminate hypnozoites from the liver and prevent relapses of vivax malaria. The World Health Organization recommends a course of 14-21 days depending on region and strain. The National Malaria Control and Eradication Programmes of Pakistan and India have adhered to a 5-day course as their standard as it is deemed more practical to implement and because facility for detecting glucose 6-phosphate dehydrogenase (G6PD) deficiency is seldom available at the periphery. Evidence for the efficacy of the 5-day regimen is controversial or lacking. Two, year-long, randomized controlled trials were undertaken in an Afghan refugee camp in north-western Pakistan using a process of passive case detection and treatment at the camp's clinic: the first trial compared treatment with chloroquine alone versus chloroquine plus 5-days primaquine, the second trial compared chloroquine alone versus chloroquine plus 14-days primaquine. Chloroquine is not hypnozoitocidal and was administered to eliminate the erythrocytic stages and to alleviate clinical symptoms. The daily primaquine dose was 0.25 mg/kg bodyweight and the total chloroquine dose was 25 mg/kg over 3 days. During the first trial 52% (129/250) of the non-primaquine group recorded a 2nd clinical-parasitaemic episode and 23% recorded a 3rd, whereas 51% (128/250) of the 5-days primaquine group reported a 2nd episode and 21% recorded a 3rd. During the second trial 49% (49/100) of the non-primaquine group recorded a 2nd episode and 25% recorded a 3rd, whereas only 32% (32/100) of the 14-days primaquine group recorded a 2nd and only 2% recorded a 3rd. The 5-days primaquine regimen has no value as an anti-relapse therapy and should be abandoned. In extended tests in vivo in which vivax cases (n = 31) were treated with chloroquine 25 mg/kg and 14-days primaquine, there was no parasite recrudescence within 28 days and hence no evidence of resistance to chloroquine.     

In vitro and in vivo evaluations of increased effective beam width for heat deposition using a split focus high intensity ultrasound (HIFU) transducer

Purpose: To develop a novel and efficient, in vitro method for characterizing temporal and spatial heat generation of focused ultrasound exposures, and evaluate this method to compare a split focus and conventional single focus high intensity focused ultrasound transducer.

Materials and methods: A HIFU tissue-mimicking phantom was validated by comparing respective temperature elevations generated in the phantoms and in murine tumors in vivo. The phantom was then used in combination with IR thermography to spatially and temporally characterize differences in low-level temperature elevation (e.g. 3–5°C) produced by a single focus and split focus HIFU transducer, where the latter produces four simultaneous foci. In vivo experiments with heat sensitive liposomes containing doxorubicin were then carried out to determine if the larger beam width of the split focus transducer, compared to the single focus, could increase overall deployment of the drug from the liposome.

Results: Temperature elevations generated in the HIFU phantom were not found to be different from those measured in vivo when compensating for disparities in attenuation coefficient and specific heat, and between the two transducers by increasing the energy deposition. Exposures with the split focus transducer provided significant increases in the area treated compared to the single focus, which then translated to significant increases in drug deposition in vivo.

Conclusions: Preliminary evidence was provided indicating the potential for using this novel technique for characterizing hyperthermia produced by focused ultrasound devices. Further development will be required for its suitability for correlating in vitro and in vivo outcomes.     

Peripapillary choroidal neovascularisation in sarcoidosis

Purpose : To describe a rare manifestation of sarcoidosis. Methods : Case report of a patient with histologically proven sarcoidosis, who developed peripapillary choroidal neovascularisation in the absence of uveitis or optic nerve disease. Results : Oral corticosteroids achieved reduction in the size of the peripapillary choroidal neovascularisation. Laser treatment was effective in treating the remaining peripapillary choroidal neovascularisation, resulting in improvement of visual acuity. Conclusions : Isolated peripapillary choroidal neovascularisation is a previously unreported complication of sarcoidosis. A combination of oral corticosteroids and laser can be successful in treating this type of lesion, thereby preventing permanent visual loss.