scholarly journals Pfmdr1 Alleles and Response to Ultralow-Dose Mefloquine Treatment in Gabonese Patients

2002 ◽  
Vol 46 (1) ◽  
pp. 166-170 ◽  
Author(s):  
Denise P. Mawili-Mboumba ◽  
Jürgen F. J. Kun ◽  
Bertrand Lell ◽  
Peter G. Kremsner ◽  
Francine Ntoumi
Keyword(s):  
Point Mutations ◽  
Chloroquine Resistance ◽  
Low Grade ◽  
Wild Type ◽  
Multidrug Resistance Gene ◽  
Ultralow Dose ◽  
Group A ◽  
The Relationship

ABSTRACT The identification of parasite molecular markers involved in resistance to antimalarial compounds is of great interest for monitoring the development and spread of resistance in the field. Polymorphisms in Plasmodium falciparum multidrug resistance gene 1 (pfmdr1) have been associated with chloroquine resistance and mefloquine susceptibility. In the present study, carried out in Lambaréné, Gabon, we investigated the relationship between the presence of mutations at codons 86, 184, 1034, 1042, and 1246 in the pfmdr1 gene and the success of ultralow-dose mefloquine treatment (1.1 mg/kg of body weight). Sixty-nine patients were included in the study, and depending on the level of in vivo resistance to mefloquine, they were classified as sensitive responders (S), patients with low-grade resistance (RI), and nonresponders (NR). We found that the prevalences of the Tyr-86 mutation among isolates from patients in groups S, RI, and NR were 100, 96, and 90%, respectively, and that the prevalence of the Phe-184 mutation among the isolates was 80% in each group. A prevalence of about 10% point mutations at codons 1042 and 1246 was detected only in isolates from patients in groups RI and NR. There was no statistically significant association between the presence of the Tyr-86 mutation and the in vivo response (P = 0.79). Among the parasite isolates from patients with drug-resistant infections, 83% had the wild-type pfmdr1 genotype (S1034-N1042-D1246). No link between the presence of this genotype and parasite resistance was detected (P = 0.42). Among the isolates analyzed, 85 had double mutations (Y86-F184 or Y86-Y1246) and 11 had triple mutations (Y86-D1042-Y1246, Y86-F184-Y1246, or Y86-F184-D1042). These findings are not consistent with those of previous in vitro studies and suggest that further evaluation of pfmdr1 gene polymorphism and in vivo mefloquine sensitivity are needed.

scholarly journals Molecular Basis of In Vivo Resistance to Sulfadoxine-Pyrimethamine in African Adult Patients Infected withPlasmodium falciparum Malaria Parasites

1998 ◽  
Vol 42 (7) ◽  
pp. 1811-1814 ◽  
Author(s):  
Leonardo K. Basco ◽  
Rachida Tahar ◽  
Pascal Ringwald
Keyword(s):  
Dihydrofolate Reductase ◽  
Point Mutations ◽  
Gene Mutations ◽  
Adult Patients ◽  
Wild Type ◽  
Dihydropteroate Synthase ◽  
Reductase Gene ◽  
Parasite Populations

ABSTRACT In vitro sulfadoxine and pyrimethamine resistance has been associated with point mutations in the dihydropteroate synthase and dihydrofolate reductase domains, respectively, but the in vivo relevance of these point mutations has not been well established. To analyze the correlation between genotype and phenotype, 10 Cameroonian adult patients were treated with sulfadoxine-pyrimethamine and followed up for 28 days. After losses to follow-up (n = 1) or elimination of DNA samples due to mixed parasite populations with pyrimethamine-sensitive and pyrimethamine-resistant profiles (n = 3), parasite genomic DNA from day 0 blood samples of six patients were analyzed by DNA sequencing. Three patients who were cured had isolates characterized by a wild-type or mutant dihydrofolate reductase gene (with one or two mutations) and a wild-type dihydropteroate synthase gene. Three other patients who failed to respond to sulfadoxine-pyrimethamine treatment carried isolates with triple dihydrofolate reductase gene mutations and either a wild-type or a mutant dihydropteroate synthase gene. Three dihydrofolate reductase gene codons (51, 59, and 108) may be reliable genetic markers that can accurately predict the clinical outcome of sulfadoxine-pyrimethamine treatment in Africa.

scholarly journals Cubitus interruptus Requires DrosophilaCREB-Binding Protein To Activate wingless Expression in theDrosophila Embryo

2000 ◽  
Vol 20 (5) ◽  
pp. 1616-1625 ◽  
Author(s):  
Yang Chen ◽  
R. H. Goodman ◽  
Sarah M. Smolik
Keyword(s):  
Transcriptional Activation ◽  
Target Genes ◽  
Binding Protein ◽  
Point Mutations ◽  
Creb Binding Protein ◽  
Wild Type ◽  
Interaction Domain ◽  
Cubitus Interruptus

ABSTRACT CREB-binding protein (CBP) serves as a transcriptional coactivator in multiple signal transduction pathways. The Drosophilahomologue of CBP, dCBP, interacts with the transcription factors Cubitus interruptus (CI), MAD, and Dorsal (DL) and functions as a coactivator in several signaling pathways during Drosophiladevelopment, including the hedgehog (hh),decapentaplegic (dpp), and Tollpathways. Although dCBP is required for the expression of thehh target genes, wingless (wg) andpatched (ptc) in vivo, and potentiatesci-mediated transcriptional activation in vitro, it is not known that ci absolutely requires dCBP for its activity. We used a yeast genetic screen to identify several ci point mutations that disrupt CI-dCBP interactions. These mutant proteins are unable to transactivate a reporter gene regulated by cibinding sites and have a lower dCBP-stimulated activity than wild-type CI. When expressed exogenously in embryos, the CI point mutants cannot activate endogenous wg expression. Furthermore, a CI mutant protein that lacks the entire dCBP interaction domain functions as a negative competitor for wild-type CI activity, and the expression of dCBP antisense RNAs can suppress CI transactivation in Kc cells. Taken together, our data suggest that dCBP function is necessary forci-mediated transactivation of wg duringDrosophila embryogenesis.

scholarly journals Clonal expansion and epigenetic reprogramming following deletion or amplification of mutant IDH1

2017 ◽  
Vol 114 (40) ◽  
pp. 10743-10748 ◽  
Author(s):  
Tali Mazor ◽  
Charles Chesnelong ◽  
Aleksandr Pankov ◽  
Llewellyn E. Jalbert ◽  
Chibo Hong ◽  
...  
Keyword(s):  
Copy Number ◽  
Cpg Island ◽  
Clonal Expansion ◽  
Low Grade ◽  
Copy Number Alterations ◽  
Wild Type ◽  
Mutant Idh1

IDH1 mutation is the earliest genetic alteration in low-grade gliomas (LGGs), but its role in tumor recurrence is unclear. Mutant IDH1 drives overproduction of the oncometabolite d-2-hydroxyglutarate (2HG) and a CpG island (CGI) hypermethylation phenotype (G-CIMP). To investigate the role of mutant IDH1 at recurrence, we performed a longitudinal analysis of 50 IDH1 mutant LGGs. We discovered six cases with copy number alterations (CNAs) at the IDH1 locus at recurrence. Deletion or amplification of IDH1 was followed by clonal expansion and recurrence at a higher grade. Successful cultures derived from IDH1 mutant, but not IDH1 wild type, gliomas systematically deleted IDH1 in vitro and in vivo, further suggestive of selection against the heterozygous mutant state as tumors progress. Tumors and cultures with IDH1 CNA had decreased 2HG, maintenance of G-CIMP, and DNA methylation reprogramming outside CGI. Thus, while IDH1 mutation initiates gliomagenesis, in some patients mutant IDH1 and 2HG are not required for later clonal expansions.

scholarly journals Mutant alcohol dehydrogenase (ADH III) presequences that affect both in vitro mitochondrial import and in vitro processing by the matrix protease.

1990 ◽  
Vol 10 (6) ◽  
pp. 2801-2808 ◽  
Author(s):  
D T Mooney ◽  
D B Pilgrim ◽  
E T Young
Keyword(s):  
Point Mutations ◽  
Wild Type ◽  
Urea Treatment ◽  
Amino Terminal ◽  
In Vitro Processing ◽  
The Matrix ◽  
Terminal Amino ◽  
Processing Protease

Point mutations in the presequence of the mitochondrial alcohol dehydrogerase isoenzyme (ADH III) have been shown to affect either the import of the precursor protein into yeast mitochondria in vivo or its processing within the organelle. In the present work, the behavior of these mutants during in vitro import into isolated mitochondria was investigated. All point mutants tested were imported with a slower initial rate than that of the wild-type precursor. This defect was corrected when the precursors were treated with urea prior to import. Once imported, the extent of processing to the mature form of mutant precursors varied greatly and correlated well with the defects observed in vivo. This result was not affected by prior urea treatment. When matrix extracts enriched for the processing protease were used, this defect was shown to be due to failure of the protease to efficiently recognize or cleave the presequence, rather than to a lack of access to the precursor. The rate of import of two ADH III precursors bearing internal deletions in the leader sequence was similar to those of the point mutants, whereas a deletion leading to the removal of the 15 amino-terminal amino acids was poorly imported. The mature amino terminus of wild-type ADH III was determined to be Gln-25. Mutant m01 (Ser-26 to Phe), which reduced the efficiency of cleavage in vitro by 80%, was cleaved at the correct site.

scholarly journals Specific protein binding to the simian virus 40 enhancer in vitro.

1986 ◽  
Vol 6 (6) ◽  
pp. 2098-2105 ◽  
Author(s):  
A G Wildeman ◽  
M Zenke ◽  
C Schatz ◽  
M Wintzerith ◽  
T Grundström ◽  
...  
Keyword(s):  
Point Mutations ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
Specific Protein ◽  
Dnase I ◽  
Wild Type ◽  
Dnase I Footprinting ◽  
Nuclear Extracts

HeLa cell nuclear extracts and wild-type or mutated simian virus 40 enhancer DNA were used in DNase I footprinting experiments to study the interaction of putative trans-acting factors with the multiple enhancer motifs. We show that these nuclear extracts contain proteins that bind to these motifs. Because point mutations which are detrimental to the activity of a particular enhancer motif in vivo specifically prevent protection of that motif against DNase I digestion in vivo, we suggest that the bound proteins correspond to trans-acting factors involved in enhancement of transcription. Using mutants in which the two domains A and B of the simian virus 40 enhancer are either separated by insertion of DNA fragments or inverted with respect to their natural orientation, we also demonstrate that the trans-acting factors bind independently to the two domains.

scholarly journals Mice Lacking Components of Adaptive Immunity Show Increased Brucella abortus virB Mutant Colonization

2007 ◽  
Vol 75 (6) ◽  
pp. 2965-2973 ◽  
Author(s):  
Hortensia García Rolán ◽  
Renée M. Tsolis
Keyword(s):  
Adaptive Immunity ◽  
Brucella Abortus ◽  
Mononuclear Phagocytes ◽  
Wild Type ◽  
Adaptive Immune ◽  
Type Iv ◽  
Absolute Requirement ◽  
The Relationship

ABSTRACT The Brucella abortus type IV secretion system (T4SS), encoded by the virB genes, is essential for survival in mononuclear phagocytes in vitro. In the mouse model, a B. abortus virB mutant was initially able to colonize the spleen at the level of the wild type for approximately 3 to 5 days, which coincided with the development of adaptive immunity. To investigate the relationship between survival in macrophages cultivated in vitro and persistence in tissues in vivo, we tested the ability of mutant mice lacking components of adaptive immunity to eliminate the virB mutant from the spleen during a mixed infection with the B. abortus wild type. Ifng −/− or β 2 m −/− mice were able to clear the virB mutant to the same degree as control mice. However, spleens of Rag1 −/− mice and Igh6 −/− mice were more highly colonized by the virB mutant than control mice after 14 to 21 days, suggesting that, in these mice, there is not an absolute requirement for the T4SS to mediate persistence of B. abortus in the spleen. Macrophages isolated from Igh6 −/− mice killed the virB mutant to the same extent as macrophages from control mice, showing that the reduced ability of these mice to clear the virB mutant from the spleen does not correlate with diminished macrophage function in vitro. These results show that in the murine model host, the T4SS is required for persistence beyond 3 to 5 days after infection and suggest that the T4SS may contribute to evasion of adaptive immune mechanisms by B. abortus.

scholarly journals The return of chloroquine-sensitive Plasmodium falciparum parasites in Jazan Region, Southwestern Saudi Arabia over a decade after the adoption of artemisinin-based combination therapy: analysis of genetic mutations in the pfcrt gene

2021 ◽  
Author(s):  
Aymen M. Madkhali ◽  
Ahmed A. Abdulhaq ◽  
Wahib M. Atroosh ◽  
Ahmad Hassn Ghzwani ◽  
Khalid Ammash Zain ◽  
...  
Keyword(s):  
Saudi Arabia ◽  
Point Mutations ◽  
Chloroquine Resistance ◽  
Wild Type ◽  
Chloroquine Resistance Transporter ◽  
Pfcrt Gene ◽  
Wild Allele ◽  
Parasitaemia Level ◽  
Single Allele

Abstract This study investigated the polymorphism in the P. falciparum chloroquine resistance transporter (pfcrt) gene 11 years after chloroquine (CQ) cessation in Jazan region, southwestern Saudi Arabia. Two hundred and thirty-five P. falciparum isolates were amplified to detect mutations in the pfcrt gene. The pfcrt 76T molecular marker for CQ resistance was detected in 66.4% (156/235) of the isolates, while the K76 CQ-sensitive wild type was detected in 33.6%. The pfcrt 74I and pfcrt 75E point mutations were each found to be present in 56.2% of isolates, while only four isolates (1.7%) were found to carry the pfcrt 72S mutation. Moreover, four pfcrt haplotypes were identified: the CVIET triple-allele (56.2%), SVMET double-allele (1.7%), and CVMNT single-allele (8.5%) mutant haplotypes, and the CVMNK wild haplotype (33.6%). The analysis also revealed significant associations between the prevalence of mutant pfcrt alleles and haplotypes and the age group, governorate, and nationality of the patients as well as the parasitaemia level (P < 0.05). The findings provide evidence of the potential re-emergence of CQ-susceptible P. falciparum strains in Jazan region over a decade after CQ discontinuation, with about one third of the isolates analysed carrying the pfcrt K76 CQ-sensitive wild allele and the CVMNK ancestral wild haplotype. Although the reintroduction of CQ cannot be recommended at present in Saudi Arabia, these findings support the rationale for a potential future role for CQ in malaria treatment. Therefore, continuous molecular and in-vitro monitoring mutations of pfcrt polymorphism in Jazan region is highly recommended.

scholarly journals Why Does Escherichia coli Grow More Slowly on Glucosamine than on N-Acetylglucosamine? Effects of Enzyme Levels and Allosteric Activation of GlcN6P Deaminase (NagB) on Growth Rates

2005 ◽  
Vol 187 (9) ◽  
pp. 2974-2982 ◽  
Author(s):  
Laura I. Álvarez-Añorve ◽  
Mario L. Calcagno ◽  
Jacqueline Plumbridge
Keyword(s):  
Escherichia Coli ◽  
Growth Rates ◽  
Sugar Transport ◽  
Point Mutations ◽  
Sole Source ◽  
Wild Type ◽  
Phosphotransferase System ◽  
Allosteric Activation

ABSTRACT Wild-type Escherichia coli grows more slowly on glucosamine (GlcN) than on N-acetylglucosamine (GlcNAc) as a sole source of carbon. Both sugars are transported by the phosphotransferase system, and their 6-phospho derivatives are produced. The subsequent catabolism of the sugars requires the allosteric enzyme glucosamine-6-phosphate (GlcN6P) deaminase, which is encoded by nagB, and degradation of GlcNAc also requires the nagA-encoded enzyme, N-acetylglucosamine-6-phosphate (GlcNAc6P) deacetylase. We investigated various factors which could affect growth on GlcN and GlcNAc, including the rate of GlcN uptake, the level of induction of the nag operon, and differential allosteric activation of GlcN6P deaminase. We found that for strains carrying a wild-type deaminase (nagB) gene, increasing the level of the NagB protein or the rate of GlcN uptake increased the growth rate, which showed that both enzyme induction and sugar transport were limiting. A set of point mutations in nagB that are known to affect the allosteric behavior of GlcN6P deaminase in vitro were transferred to the nagB gene on the Escherichia coli chromosome, and their effects on the growth rates were measured. Mutants in which the substrate-induced positive cooperativity of NagB was reduced or abolished grew even more slowly on GlcN than on GlcNAc or did not grow at all on GlcN. Increasing the amount of the deaminase by using a nagC or nagA mutation to derepress the nag operon improved growth. For some mutants, a nagA mutation, which caused the accumulation of the allosteric activator GlcNAc6P and permitted allosteric activation, had a stronger effect than nagC. The effects of the mutations on growth in vivo are discussed in light of their in vitro kinetics.

scholarly journals SH-1028, An Irreversible Third-Generation EGFR TKI, Overcomes T790M-Mediated Resistance in Non-Small Cell Lung Cancer

2021 ◽  
Vol 12 ◽  
Author(s):  
Luwei Han ◽  
Xiaomeng Zhang ◽  
Zhiqiang Wang ◽  
Xian Zhang ◽  
Liwen Zhao ◽  
...  
Keyword(s):  
Third Generation ◽  
Wild Type ◽  
Egfr Inhibition ◽  
Erk Phosphorylation ◽  
Xenograft Models ◽  
The Relationship ◽  
Egfr Tki ◽  
Resistant Mutation

SH-1028 is an irreversible third-generation EGFR TKI. Both SH-1028 and osimertinib have a pyrimidine structure (a typical mutant-selective EGFR TKI structure). Compared with osimertinib, SH-1028 is modified on the indole ring, thus resulting in a more stable 6,7,8,9-tetrahydro-pyrrolo [1, 2-a] indol structure. In this study, we explored the anti-tumor effect of SH-1028 in vitro and in vivo, the inhibition of cell signal, such as EGFR and ERK phosphorylation, and verified the relationship between the pharmacokinetics and pharmacodynamic responses. Firstly, SH-1028 selectively inhibited EGFR sensitive and resistant mutations, with up to 198-fold more effective compared with wild-type EGFR cells. Then, in mouse xenograft models, oral administration of SH-1028 at a daily dose of 5 mg/kg significantly inhibited proliferation of tumor cells with EGFR sensitive mutation (exon 19 del) and resistant mutation (T790 M) for consecutive 14 days, with no TKI-induced weight loss. Moreover, SH-1028 exhibited good bioavailability, and was distributed extensively from the plasma to the tissues. The main metabolite of SH-1028, Imp3, was tested and showed no wild-type EGFR inhibition or off-target effects. In conclusion, SH-1028 is a new third-generation EGFR inhibitor that exhibits potent activity against EGFR sensitive and resistant (T790 M) mutations.

Sign in / Sign up

Export Citation Format

Share Document