Comprehensive Lifestyle Improvement Program for Prostate Cancer (CLIPP) is associated with improvement in weight and components of metabolic syndrome in men exposed to androgen deprivation therapy for prostate cancer.

BACKGROUND: Androgen deprivation therapy (ADT) for prostate cancer is associated with adverse effects, such as obesity and metabolic syndrome, which increase cardiovascular risk, the most common cause of non-cancer mortality in men diagnosed with prostate cancer. The Comprehensive Lifestyle Improvement Program for Prostate Cancer (CLIPP) was created to determine the feasibility of conducing a comprehensive lifestyle modification intervention in men on ADT for prostate cancer and determine its early efficacy in reducing obesity and metabolic syndrome. METHODS: A single-arm, open-label clinical trial was conducted by recruiting 31 men diagnosed with prostate cancer and exposed to ADT within the last 5 years. A multicomponent lifestyle modification program was delivered weekly for 16 weeks by a trained health coach. This was followed by 8 weeks of passive follow-up resulting in a total trial duration of 24 weeks. Feasibility was determined by calculating study recruitment, retention, and adherence rates. Weight and components of metabolic syndrome (waist circumference, triglycerides (TG), high-density lipoprotein (HDL), serum glucose, and blood pressure (BP)) were measured at baseline, 12, and 24 weeks. RESULTS: Recruitment, retention, and adherence rates were 47.1%, 90.3%, and 100%, respectively. Statistically significant improvements were noted between baseline and end of study measurements for weight (206.3 vs. 191.3 lbs, p < 0.001), waist (41.3 vs. 38.8 inches, p < 0.001), systolic BP (144.1 vs. 133.4 mm of Hg, p = 0.014), diastolic BP (83.3 vs. 76.2 mm of Hg, p = 0.0056), TG (146.0 vs. 113.8 mg/dl, p = 0.022), HDL (51.1 vs. 55.0 mg/dl, p = 0.012), and serum glucose (114.0 vs. 103.2 mg/dl, p = 0.013). CONCLUSION: CLIPP demonstrates feasibility and early efficacy of a multicomponent lifestyle modification intervention toward addressing obesity as well as components of metabolic syndrome in men on ADT for prostate cancer. This study provides strong preliminary data to develop future clinical trials in this population.

Protocol for a feasibility and early efficacy study of the Comprehensive Lifestyle Improvement Program for Prostate Cancer-2 (CLIPP2).

BACKGROUND: Although androgen deprivation therapy (ADT) for prostate cancer demonstrates improved overall and disease-free survival, it is associated with adverse effects such as obesity and metabolic syndrome that increase risk of cardiometabolic disease and diabetes type 2. ADT also leads to fatigue, depression and erectile dysfunction, which reduce quality of life (QoL). Lifestyle modification has shown promise in reducing obesity, metabolic syndrome and diabetes type 2 in other disease types. However, there is a paucity of data regarding the utility of lifestyle modification in men receiving ADT for prostate cancer. METHODS: The primary aim of the Comprehensive Lifestyle Improvement Program for Prostate Cancer-2 (CLIPP2) is to test the feasibility of conducting a 24-week lifestyle modification intervention in men on ADT for prostate cancer. Additionally, it will also determine the effect of this intervention on weight loss, cardiometabolic markers (secondary aim and markers of interest: serum glucose, insulin resistance, hemoglobin A1C and lipid panel), and QoL (tertiary aim). The intervention will be delivered weekly via telephone for the first 10 weeks and bi-weekly for the remaining 14 weeks. Questionnaires and serum samples will be collected at baseline, week 12, and week 24. Anthropometric measurements will be collected at baseline, week 6, week 12, week 18 and week 24. RESULTS: We hypothesize that the CLIPP2 intervention will produce a 7% weight loss that will result in improved markers associated with cardiometabolic disease and type 2 diabetes in the study population. CONCLUSION: Results will provide insight into the role of lifestyle modification in addressing ADT adverse effects as well as provide preliminary data to inform the development of future lifestyle interventions in this area. TRIAL REGISTRATION: NCT04228055 Clinicaltrials. gov.

SARS-CoV-2 and Plasmodium falciparum common immunodominant regions may explain low COVID-19 incidence in the malaria-endemic belt.

Coronavirus disease 2019 (COVID-19) has caused significant morbidity and mortality and new cases are on the rise globally, yet malaria-endemic areas report statistically significant lower incidences. We identified potential shared targets for an immune response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by immune determinants' shared identities with P. falciparum using the Immune Epitope Database and Analysis Resource Immune 9.0 browser tool. Probable cross-reactivity is suggested through HLA-A∗02:01 and subsequent CD8+ T-cell activation. The apparent immunodominant epitope conservation between SARS-CoV-2 (N and open reading frame (ORF) 1ab) and P. falciparum thrombospondin-related anonymous protein (TRAP) may underlie the low COVID-19 incidence in the malaria-endemic zone by providing immunity against virus infection to those previously infected with Plasmodium. Additionally, we hypothesize that the shared epitopes which lie within antigens that aid in the establishment of the P. falciparum erythrocyte invasion may be an alternative route for SARS-CoV-2 via the erythrocyte CD147 receptor, although this remains to be proven.

A Multicenter Pilot Study on the Clinical Utility of Computational Modeling for Flow-Diverter Treatment Planning.

BACKGROUND AND PURPOSE: Selection of the correct flow-diverter size is critical for cerebral aneurysm treatment success, but it remains challenging due to the interplay of device size, anatomy, and deployment. Current convention does not address these challenges well. The goals of this pilot study were to determine whether computational modeling improves flow-diverter sizing over current convention and to validate simulated deployments. MATERIALS AND METHODS: Seven experienced neurosurgeons and interventional neuroradiologists used computational modeling to prospectively plan 19 clinical interventions. In each patient case, physicians simulated 2-4 flow-diverter sizes that were under consideration based on preprocedural imaging. In addition, physicians identified a preferred device size using the current convention. A questionnaire on the impact of computational modeling on the procedure was completed immediately after treatment. Rotational angiography image data were acquired after treatment and compared with flow-diverter simulations to validate the output of the software platform. RESULTS: According to questionnaire responses, physicians found the simulations useful for treatment planning, and they increased their confidence in device selection in 94.7% of cases. After viewing the simulations results, physicians selected a device size that was different from the original conventionally planned device size in 63.2% of cases. The average absolute difference between clinical and simulated flow-diverter lengths was 2.1 mm. In 57% of cases, average simulated flow-diverter diameters were within the measurement uncertainty of clinical flow-diverter diameters. CONCLUSIONS: Physicians found computational modeling to be an impactful and useful tool for flow-diverter treatment planning. Validation results showed good agreement between simulated and clinical flow-diverter diameters and lengths.

Anopheles arabiensis in Sudan: a noticeable tolerance to urban polluted larval habitats associated with resistance to Temephos.

BACKGROUND: It has been documented that unplanned urbanization leads to the exposure of members of the Anopheles vectors to a range of water pollution in urban settings. Many surveys from African and Asian countries reported the presence of Anopheles larvae in polluted urban habitats. The present study documents an obvious tolerance of the melanic and normal forms of Anopheles arabiensis to urban polluted larval habitats accompanied by resistance to Temephos larvicide. METHODS: A cross-sectional survey was carried out to inspect apparently polluted An. arabiensis larval habitats during the hot dry season of 2015. Larval specimens were collected from only apparently polluted habitats after visual inspection from 5 localities in Khartoum State. After morphological and molecular identification of random samples of larvae the magnitude of water pollution was determined using nine abiotic factors. The susceptibility status of An. arabiensis larval forms from normal and polluted habitats to Temephos was tested using the WHO standard diagnostic concentration doses. RESULTS: Morphological and PCR analysis of anopheline larvae revealed the presence of An. arabiensis, a member of the Anopheles gambiae complex. Seven out of 9 physiochemical parameters showed higher concentrations in polluted larval habitats in comparison to control site. Anopheles arabiensis larvae were found in water bodies characterized by high mean of conductivity (1857.8 ± 443.3 uS/cm), turbidity (189.4 ± 69.1 NTU) and nitrate (19.7 ± 16.7 mg/l). The range of mortality rates of An. arabiensis larvae collected from polluted habitats in comparison to An. arabiensis larvae collected from non-polluted habitats was 6.7-64% (LD50 = 1.682) and 67.6-96% (LD50 = 0.806), respectively. CONCLUSIONS: The present study reveals that minor populations of An. arabiensis larval forms are adapted to breed in polluted urban habitats, which further influenced susceptibility to Temephos, especially for the melanic larval forms. This could have further implications on the biology of the malaria vector and on the transmission and epidemiology of urban malaria in Sudan.

The effect of PD-L1 testing on the cost-effectiveness and economic impact of immune checkpoint inhibitors for the second-line treatment of NSCLC.

BACKGROUND: Immune checkpoint inhibitors improve outcomes compared with chemotherapy in lung cancer. Tumor PD-L1 receptor expression is being studied as a predictive biomarker. The objective of this study was to assess the cost-effectiveness and economic impact of second-line treatment with nivolumab, pembrolizumab, and atezolizumab with and without the use of PD-L1 testing for patient selection. DESIGN: We developed a decision-analytic model to determine the cost-effectiveness of PD-L1 assessment and second-line immunotherapy versus docetaxel. The model used outcomes data from randomized clinical trials (RCTs) and drug acquisition costs from the United States. Thereafter, we used epidemiologic data to estimate the economic impact of the treatment. RESULTS: We included four RCTs (2 with nivolumab, 1 with pembrolizumab, and 1 with atezolizumab). The incremental quality-adjusted life year (QALY) for nivolumab was 0.417 among squamous tumors and 0.287 among non-squamous tumors and the incremental cost-effectiveness ratio (ICER) were $155 605 and $187 685, respectively. The QALY gain in the base case for atezolizumab was 0.354 and the ICER was $215 802. Compared with treating all patients, the selection of patients by PD-L1 expression improved incremental QALY by up to 183% and decreased the ICER by up to 65%. Pembrolizumab was studied only in patients whose tumors expressed PD-L1. The QALY gain was 0.346 and the ICER was $98 421. Patient selection also reduced the budget impact of immunotherapy. CONCLUSION: The use of PD-L1 expression as a biomarker increases cost-effectiveness of immunotherapy but also diminishes the number of potential life-years saved.

Molecular cloning, polymorphism, and functional activity of the bovine and water buffalo Mx2 gene promoter region.

BACKGROUND: Bovine Mx2 gene sequences were already reported, but further information about the gene properties is not yet available. The objective of the current study was to elucidate the structural properties of the bovine Mx2 gene mainly the promoter region and its possible functional role. If available, such information would help in assessing the functional properties of the gene, which was reported to confer antiviral action against recombinant VSV. RESULTS: Examinations on the bovine genomic BAC clone-confirmed to contain the Mx2 gene-revealed 883-bp sequences. A computer scan unequivocally identified a 788-bp promoter region containing a typical TATA box, three ISREs and other promoter-specific motifs. Comparative analysis of nine bovine genomic DNA samples showed 19 nucleotide substitutions suggesting the existence of five different genotypes in the promoter region. The water buffalo Mx2 promoter region was determined by using primers based on the bovine Mx2 promoter region disclosing 893-bp, with 56 substitutions, two insertions, 9 and 1 nt at two different sites. A functional analysis of the putative ISRE indicated that ISRE played a synergetic role in the activation of bovine Mx2 gene transcription. CONCLUSION: Bovine and water buffalo Mx2 promoter region was identified disclosing, the conserved ISRE, located in the proximal end of the promoter region like other members of the antiviral family, suggesting functional activity under interferon stimulation.

Ellagic acid protects against cisplatin-induced nephrotoxicity in rats: a dose-dependent study.

BACKGROUND: The anticancerdrug cisplatin (CP) causes nephrotoxicity through different mechanisms, including generation of free radicals. Ellagic acid (EA) is a polyphenolic antioxidant found in fruits and nuts. AIM: This study aimed to investigate the ability of different doses of EA to ameliorate CP nephrotoxicity in rats. MATERIALS AND METHODS: Animals were randomly divided into six groups and treated with saline; CP alone (6 mg/kg); two doses of EA, both alone (10 and 30 mg/kg) or with CP. RESULTS: Treatment with CP alone reduced body weight, water intake, urine output, and renal total antioxidant and reduced glutathione (GSH) concentrations (p < 0.01). In addition, it increased relative kidney weight, plasma creatinine, and blood urea nitrogen (BUN) concentrations (p < 0.01). However, a dose of 30 mg/kg EA mitigated most of the CP-induced actions, but no effect was seen for the 10 mg/kg dose. Histopathologically, rats given CP+EA30 showed < 25% necrotic lesions in the renal cortical area compared with > 60% in rats treated with CP alone. Molecular analysis showed that clusterin (Clu) mRNA and protein were expressed in all treated groups, meanwhile kidney injury molecule-1 (Kim-1) mRNA and protein were only expressed in the CP and CP+EA treated rats. CONCLUSIONS: EA (30 mg/kg) ameliorated most of the physiological, histological, and biochemical markers of CP nephrotoxicity. The molecular findings in this work did not completely tally with the conventional method used. The overexpression of the molecular markers may be related to the EA induced repair mechanism.

Bovine and water buffalo Mx2 genes: polymorphism and antiviral activity.

Millennia-long selective pressure of single-strand RNA viruses on the bovine Mx locus has increased the advantages of using the bovine Mx protein to evaluate the ultimate significance of the antiviral role of Mx proteins. The conclusions of research based only on the bovine Mx1 protein showed the need for comprehensive studies that demonstrate the role of all isoforms, individually or together, especially in the presence of a second isoform, the bovine Mx2 gene. This study provides information about bovine and water buffalo Mx2 genes, as well as their allelic polymorphism and basic antiviral potential. Observation of an Mx2 cDNA sequence (2,381 bp) obtained from 15 animals from 11 breeds using primers based on a previous sequence (NCBI accession no. AF335147) revealed several nucleotide substitutions, with eight different alleles and two amino acid exchanges: Gly to Ser at position 302 and Ile to Val at position 354, though the latter was found only in the NCBI database. A water buffalo Mx2 cDNA sequence was identified for the first time, revealing 46 nucleotide substitutions with 12 amino acid variations, in addition to a 9-bp insertion in the 5' untranslated region UTR, compared with the bovine Mx2 cDNA. Transfected 3T3 cells expressing bovine Mx2 mRNAs coding Gly or Ser at position 302, water buffalo Mx2 mRNA, positive control bovine Mx1 mRNA-expressing cells, and negative control parental 3T3 were subjected to infection with recombinant vesicular stomatitis virus (VSVDeltaG*-G), as were empty pCI-neo vector-transfected cells. The positive control and all cells expressing Mx2 mRNAs displayed significantly higher levels of antiviral activity against VSVDeltaG*-G (P < 0.01) than did the negative controls.

Genetic complexity and gametocyte production of Plasmodium falciparum in Fulani and Mossi communities in Burkina Faso.

We have examined Plasmodium falciparum gametocyte prevalence, density and their genetic complexity among children of 2 sympatric ethnic groups (Mossi and Fulani) in villages in Burkina Faso. The 2 groups are known to have distinct differences in their susceptibility and immune responses to malaria. We used RT-PCR and sequence-specific probes to detect and type RNA of the gametocyte-specific protein Pfs48/45. There were no differences in detection rates of asexual forms and gametocytes among the 2 groups, using PCR and RT-PCR, respectively. However, there were significant differences in densities of asexual forms and gametocytes, which were both higher among Mossi than Fulani. Both asexual forms and gametocyte densities were influenced by age and ethnicity. Multiple-clone infections with more than 1 gametocyte genotype were equally prevalent among Fulani and Mossi. These differences can most probably be attributed to genetic differences in malaria susceptibility in the 2 ethnic groups.

Local differentiation in Plasmodium falciparum drug resistance genes in Sudan.

Studies of population genetic structure of parasites can be used to infer which parasite genes are under selection. Here, the population structure of 4 genes associated with drug resistance of Plasmodium falciparum (the chloroquine resistance transporter, pfcrt, dihydrofolate reductase, dhfr, dihydropteroate synthase, dhps, and multi-drug resistance, pfmdr-1) were examined in parasite populations in 3 villages in eastern Sudan and in an urban area of Khartoum, the capital. In order to differentiate the effects of drug selection from neutral influences on population structure, parasites were also genotyped for 3 putatively neutral microsatellite loci (polyalpha, TA81 and pfg377), and for 2 antigenic loci that are either under balancing selection or neutral, merozoite surface protein 1 and 2, (MSP-1 and MSP-2). Cross-sectional surveys were carried out during the peak transmission (wet) season and in the ensuing dry season. No significant variation in frequencies of MSP-1 and MSP-2 alleles was seen among villages in the eastern region and between the villages and Khartoum, nor between the wet and dry season. However, the drug resistance genes, pfmdr-1, pfcrt and dhfr and to a lesser extent the microsatellite loci showed high FST values when comparing villages with Khartoum, indicating strong geographical differentiation at these loci. Moreover, variation in frequencies of the drug resistance genes, pfmdr-1, pfcrt and dhfr, was observed between the wet and dry season. These differences most probably reflect the variation in drug pressure between each region, and in drug usage between the wet and dry season in a given region.

Critical comparison of molecular genotyping methods for detection of drug-resistant Plasmodium falciparum.

We have critically evaluated 3 techniques for the detection of mutations conferring drug resistance of Plasmodium falciparum, using samples containing known numbers of well-characterized parasites and artificial mixtures of these parasites at known proportions. We compared the sensitivity and specificity of mutation-specific polymerase chain reaction (MS-PCR), polymerase chain reaction followed by restriction enzyme digestion at polymorphic sites (PCR/RFLP), and a dot-blot/probe hybridization technique, for detection of point mutations at nucleotide 323 of the P. falciparum dihydrofolate reductase gene (dhfr) that confer resistance to the antimalarial drug pyrimethamine. We have also investigated the benefits in terms of sensitivity and reproducibility of the incorporation of radiolabelled nucleotides into the PCR/RFLP assay. We found that MS-PCR was very sensitive--at least 10 parasites could be detected in a sample--but non-specific amplification resulted in erroneous typing of some samples. PCR/RFLP was less sensitive; 10 parasites per sample could not always be detected, but the technique was specific. The addition of radiolabelled nucleotides to the assay did not markedly improve the sensitivity but the results were easier to read and there was less subjectivity in scoring the results. The dot-blot/probe hybridization technique was specific and sensitive, with similar levels of specificity and sensitivity to PCR/RFLP. On balance, the dot-blot/probe hybridization technique seems best suited to large-scale epidemiological surveys of genes associated with antimalarial drug resistance.

Diversity of Plasmodium falciparum clones infecting children living in a holoendemic area in north-eastern Tanzania.

The diversity of Plasmodium falciparum clones and their role in progression from asymptomatic to symptomatic condition in children have been investigated. Attempts to identify whether particular parasite genotypes were associated with the development of clinical symptoms have been made. A cohort of 34 initially asymptomatic parasitaemic children aged 1-5 years were followed daily for 31 days. Clinical examinations were made each day for signs and symptoms of clinical malaria, followed by parasitological investigation. Nineteen children developed symptoms suggestive of clinical malaria during this period. Daily blood parasite samples from 13 children who developed clinical malaria symptoms and 7 who remained asymptomatic were genotyped by PCR-amplification of the polymorphic regions of the merozoite surface proteins 1 and 2 (MSP1 and MSP2) and the glutamate rich protein (GLURP) genes. Infections were found to be highly complex in both groups of children. Every isolate examined from both groups had a mixture of parasite clones. Daily changes were observed in both parasite density and genotypic pattern. The mean number of genotypes per individual was estimated at 4.9 and 2.7 for asymptomatic and symptomatic groups of children, respectively. Analysis of allele frequency distributions showed that these differed significantly for the MSP1 locus only.

Efficacy of Sulphadoxine and Pyrimethamine, Doxycycline and their combination in the treatment of chloroquine resistant Falciparum Malaria.

OBJECTIVE: The present in vivo study evaluates the efficacy of sulphadoxine/pyrimethamine, doxycycline and their combination in the treatment of Sudanese patients infected by chloroquine resistant falciparum malaria. METHODS: Febrile patients with positive blood smears of Plasmodium falciparum were given chloroquine 25mg-base/kg body weight and followed up for 3 days. Patients with recrudescence due to chloroquine resistance were readmitted for test treatment. Using simple number randomization patients were divided into groups, A, B and C. These were treated with doxycycline, sulphadoxine/ pyrimethamine and a combination therapy of sulphadoxine/pyrimethamine plus doxycycline. Doxycycline was initially administered as a single dose of 200mg followed by 100mg daily for 6 days whereas sulphadoxine/pyrimethamine was given as a single dose of sulphadoxine 1500mg and pyrimethamine 75mg. Patients of group C received the combination therapy of sulphadoxine/pyrimethamine and doxycycline. Clinical observations and examination of blood films were carried out for each patient daily for 6 days and thereafter weekly for 4 weeks. RESULTS: A high level of chloroquine resistance (75%) was documented amongst 280 patients (age 15-53 years) visiting Omdurman Hospital of Endemic Diseases during 1996-1998. The study demonstrated that only 46% and 78% of the patients were cured after 4 days of treatment by doxycycline and sulphadoxine/pyrimethamine. Patients treated with sulphadoxine/pyrimethamine in combination with doxycycline had a cure rate of 90% and 100% after 3-4 days of treatment, a single recrudescent case was detected on day 6. No relapses occurred during the follow up period. All patients were successfully treated by all regimens with the exception of one case treated by doxycycline. All treatments were well tolerated but a few cases had complaints of nausea. CONCLUSION: The combination therapy of doxycycline/sulphadoxine/pyrimethamine appeared to be significantly effective in the treatment of patients with chloroquine resistant falciparum malaria without causing any serious side effects. Such a combination regimen has the advantages of being available at a reasonable cost and less prone to development of resistance.

Population genetic analysis of the Plasmodium falciparum erythrocyte binding antigen-175 (eba-175) gene.

The Plasmodium falciparum erythrocyte binding antigen-175 gene (eba-175) has highly divergent allelic segments (Cseg and Fseg) in one part of the gene (region III), but only a small number of single nucleotide polymorphisms (SNPs) in the rest of the sequence. Here, evidence for the possible importance of the Cseg/Fseg dimorphism was sought in a molecular population genetic analysis of the gene. First, allele frequency distributions were determined for the Cseg/Fseg dimorphism and five SNPs in a sample of five populations in Africa. The inter-population variance in frequencies was higher for Cseg/Fseg (F(ST)=0.18) than for the SNPs (F(ST) values from 0.03 to 0.10), but these values were entirely dependent on the inclusion of one particularly divergent population (Sudan). Second, linkage disequilibrium was measured among the intragenic loci. There was the expected trend of declining linkage disequilibrium with increasing molecular distance, but it is notable that the Cseg allele was in absolute linkage disequilibrium with the two flanking SNPs, whereas the Fseg allele was associated with a broader range of SNP haplotypes. Finally, there was no association between the Cseg/Fseg alleles of eba-175 in parasites and the M/N alleles of the glycophorin A erythrocyte receptor in the human subjects.

Chlorinated alkaloids in Menispermum dauricum DC: root culture.

Feeding experiments using (36)Cl showed that Menispermum dauricum root culture produces four alkaloids containing chlorine. They included the novel alkaloids dauricumine and dauricumidine as well as the known alkaloids acutumine and acutumidine. The structures of novel alkaloids were established by spectroscopic, crystallographic, and chemical methods. These four alkaloids were labeled with (36)Cl, isolated, and fed independently to root cultures. Mutual conversion between acutumine and acutumidine, and between dauricumine and dauricumidine by N-methylation and N-demethylation, was demonstrated. Moreover, dauricumine was converted to acutumine and acutumidine. Epimerization of acutumidine to dauricumidine or vice versa was not observed. These results suggest that dauricumine is the first chlorinated alkaloid formed in cultured M. dauricum roots. Skewed distribution of radioactivity derived from labeled dauricumine is proof that epimerization at C-1 proceeds at a lower rate than N-demethylation.

Genotyping of Plasmodium falciparum infections by PCR: a comparative multicentre study.

Genetic diversity of malaria parasites represents a major issue in understanding several aspects of malaria infection and disease. Genotyping of Plasmodium falciparum infections with polymerase chain reaction (PCR)-based methods has therefore been introduced in epidemiological studies. Polymorphic regions of the msp1, msp2 and glurp genes are the most frequently used markers for genotyping, but methods may differ. A multicentre study was therefore conducted to evaluate the comparability of results from different laboratories when the same samples were analysed. Analyses of laboratory-cloned lines revealed high specificity but varying sensitivity. Detection of low-density clones was hampered in multiclonal infections. Analyses of isolates from Tanzania and Papua New Guinea revealed similar positivity rates with the same allelic types identified. The number of alleles detected per isolate, however, varied systematically between the laboratories especially at high parasite densities. When the analyses were repeated within the laboratories, high agreement was found in getting positive or negative results but with a random variation in the number of alleles detected. The msp2 locus appeared to be the most informative single marker for analyses of multiplicity of infection. Genotyping by PCR is a powerful tool for studies on genetic diversity of P. falciparum but this study has revealed limitations in comparing results on multiplicity of infection derived from different laboratories and emphasizes the need for highly standardized laboratory protocols.

High-level chloroquine resistance in Sudanese isolates of Plasmodium falciparum is associated with mutations in the chloroquine resistance transporter gene pfcrt and the multidrug resistance Gene pfmdr1.

Polymorphisms were examined in 2 Plasmodium falciparum genes, as were chloroquine responses of clones and isolates from a village in eastern Sudan. There was a significant association between an allele of the P. falciparum chloroquine resistance transporter gene (pfcrt-T76) and both in vitro and in vivo resistance. There was a less significant association with the multidrug resistance gene pfmdr1-Y86 allele. A significant association between pfmdr1-Y86 and pfcrt-T76 was apparent among resistant isolates, which suggests a joint action of the 2 genes in high-level chloroquine resistance.