Showing papers by "St. Jude Children's Research Hospital published in 2001"
TL;DR: Results show that expression of the Bcrp1/ABCG2 gene is an important determinant of the SP phenotype, and that it might serve as a marker for stem cells from various sources.
Abstract: Stem cells from bone marrow, skeletal muscle and possibly other tissues can be identified by the 'side-population' (SP) phenotype. Although it has been assumed that expression of ABC transporters is responsible for this phenotype, the specific molecules involved have not been defined. Here we show that expression of the Bcrp1 (also known as Abcg2 murine/ABCG2 human) gene is a conserved feature of stem cells from a wide variety of sources. Bcrp1 mRNA was expressed at high levels in primitive murine hematopoietic stem cells, and was sharply downregulated with differentiation. Enforced expression of the ABCG2 cDNA directly conferred the SP phenotype to bone-marrow cells and caused a reduction in maturing progeny both in vitro and in transplantation-based assays. These results show that expression of the Bcrp1/ABCG2 gene is an important determinant of the SP phenotype, and that it might serve as a marker for stem cells from various sources.
2,309 citations
TL;DR: The resultant primer set is suitable for all influenza A viruses to generate full-length cDNAs, to subtype viruses, to sequence their DNA, and to construct expression plasmids for reverse genetics systems.
Abstract: To systematically identify and analyze the 15 HA and 9 NA subtypes of influenza A virus, we need reliable, simple methods that not only characterize partial sequences but analyze the entire influenza A genome. We designed primers based on the fact that the 15 and 21 terminal segment specific nucleotides of the genomic viral RNA are conserved between all influenza A viruses and unique for each segment. The primers designed for each segment contain influenza virus specific nucleotides at their 3'-end and non-influenza virus nucleotides at the 5'-end. With this set of primers, we were able to amplify all eight segments of N1, N2, N4, N5, and N8 subtypes. For N3, N6, N7, and N9 subtypes, the segment specific sequences of the neuraminidase genes are different. Therefore, we optimized the primer design to allow the amplification of those neuraminidase genes as well. The resultant primer set is suitable for all influenza A viruses to generate full-length cDNAs, to subtype viruses, to sequence their DNA, and to construct expression plasmids for reverse genetics systems.
1,924 citations
TL;DR: Allelic variation in MDR1 is more common than previously recognized and involves multiple SNPs whose allelic frequencies vary between populations, and some of these SNPs are associated with altered P‐glycoprotein function.
Abstract: MDR1 (P-glycoprotein) is an important factor in the disposition of many drugs, and the involved processes often exhibit considerable interindividual variability that may be genetically determined. Single-strand conformational polymorphism analysis and direct sequencing of exonic MDR1 deoxyribonucleic acid from 37 healthy European American and 23 healthy African American subjects identified 10 single nucleotide polymorphisms (SNPs), including 6 nonsynonymous variants, occurring in various allelic combinations. Population frequencies of the 15 identified alleles varied according to racial background. Two synonymous SNPs (C1236T in exon 12 and C3435T in exon 26) and a nonsynonymous SNP (G2677T, Ala893Ser) in exon 21 were found to be linked (MDR1*2 ) and occurred in 62% of European Americans and 13% of African Americans. In vitro expression of MDR1 encoding Ala893 (MDR1*1 ) or a site-directed Ser893 mutation (MDR1*2 ) indicated enhanced efflux of digoxin by cells expressing the MDR1-Ser893 variant. In vivo functional relevance of this SNP was assessed with the known P-glycoprotein drug substrate fexofenadine as a probe of the transporter's activity. In humans, MDR1*1 and MDR1*2 variants were associated with differences in fexofenadine levels, consistent with the in vitro data, with the area under the plasma level-time curve being almost 40% greater in the *1/*1 genotype compared with the *2/*2 and the *1/*2 heterozygotes having an intermediate value, suggesting enhanced in vivo P-glycoprotein activity among subjects with the MDR1*2 allele. Thus allelic variation in MDR1 is more common than previously recognized and involves multiple SNPs whose allelic frequencies vary between populations, and some of these SNPs are associated with altered P-glycoprotein function.
1,000 citations
TL;DR: A complex signalling network that interconnects the activities of RB and p53 monitors oncogenic stimuli to provide a cell-autonomous mode of tumour surveillance.
Abstract: The retinoblastoma protein (RB) and p53 transcription factor are regulated by two distinct proteins that are encoded by the INK4a/ARF locus. Genes encoding these four tumour suppressors are disabled, either in whole or in part, in most human cancers. A complex signalling network that interconnects the activities of RB and p53 monitors oncogenic stimuli to provide a cell-autonomous mode of tumour surveillance.
953 citations
TL;DR: It is reported for the first time that impaired but not abolished NF-κB signaling in humans results in two related syndromes that associate specific developmental and immunological defects.
Abstract: The molecular basis of X-linked recessive anhidrotic ectodermal dysplasia with immunodeficiency (EDA-ID) has remained elusive. Here we report hypomorphic mutations in the gene IKBKG in 12 males with EDA-ID from 8 kindreds, and 2 patients with a related and hitherto unrecognized syndrome of EDA-ID with osteopetrosis and lymphoedema (OL-EDA-ID). Mutations in the coding region of IKBKG are associated with EDA-ID, and stop codon mutations, with OL-EDA-ID. IKBKG encodes NEMO, the regulatory subunit of the IKK (IκB kinase) complex, which is essential for NF-κB signaling. Germline loss-of-function mutations in IKBKG are lethal in male fetuses. We show that IKBKG mutations causing OL-EDA-ID and EDA-ID impair but do not abolish NF-κB signaling. We also show that the ectodysplasin receptor, DL, triggers NF-κB through the NEMO protein, indicating that EDA results from impaired NF-κB signaling. Finally, we show that abnormal immunity in OL-EDA-ID patients results from impaired cell responses to lipopolysaccharide, interleukin (IL)-1β, IL-18, TNFα and CD154. We thus report for the first time that impaired but not abolished NF-κB signaling in humans results in two related syndromes that associate specific developmental and immunological defects.
748 citations
TL;DR: During the past few years studies from several laboratories have utilized gene disruption approaches to define the function of members of the Stat family of transcription factors, and it has been demonstrated that each family member has unique, critical, non-redundant functions in signal transduction throughMembers of the cytokine receptor superfamily.
703 citations
TL;DR: The identification of reelin has challenged many of the authors' previous notions and has led to a new vision of the events involved in the migration of neurons.
Abstract: The neurological mutant mouse reeler has played a critical role in the evolution of our understanding of normal brain development. From the earliest neuroanatomic studies of reeler, it was anticipated that the characterization of the gene responsible would elucidate important molecular and cellular principles governing cell positioning and the formation of synaptic circuits in the developing brain. Indeed, the identification of reelin has challenged many of our previous notions and has led to a new vision of the events involved in the migration of neurons. Several neuronal populations throughout the brain secrete Reelin, which binds to transmembrane receptors located on adjacent cells triggering a tyrosine kinase cascade. This allows neurons to complete migration and adopt their ultimate positions in laminar structures in the central nervous system. Recent studies have also suggested a role for the Reelin pathway in axonal branching, synaptogenesis, and pathology underlying neurodegeneration.
661 citations
TL;DR: In vitro and in vivo, extracellularly orientated ceramide, released upon CD95-triggered translocation of ASM to the plasma membrane outer surface, enabled clustering of CD95 in sphingolipid-rich membrane rafts and apoptosis induction.
628 citations
TL;DR: Evidence is provided for a novel, noninvasive approach for targeting potential therapeutic factors to the central nervous system using genetically-modified hematopoietic cells enter the CNS and differentiate into microglia after bone-marrow transplantation.
Abstract: Gene therapy in the central nervous system (CNS) is hindered by the presence of the blood-brain barrier, which restricts access of serum constituents and peripheral cells to the brain parenchyma. Expression of exogenously administered genes in the CNS has been achieved in vivo using highly invasive routes, or ex vivo relying on the direct implantation of genetically modified cells into the brain. Here we provide evidence for a novel, noninvasive approach for targeting potential therapeutic factors to the CNS. Genetically-modified hematopoietic cells enter the CNS and differentiate into microglia after bone-marrow transplantation. Up to a quarter of the regional microglial population is donor-derived by four months after transplantation. Microglial engraftment is enhanced by neuropathology, and gene-modified myeloid cells are specifically attracted to the sites of neuronal damage. Thus, microglia may serve as vehicles for gene delivery to the nervous system.
621 citations
TL;DR: The results clarify the checkpoint roles for each of these three gene products, demonstrate that control of cell cycle arrests must now be included among the important functions of Brca1 in cellular responses to DNA damage, and suggest that Atm phosphorylation of BrCA1 is required for the G2/M checkpoint.
Abstract: Cell cycle arrests in the G(1), S, and G(2) phases occur in mammalian cells after ionizing irradiation and appear to protect cells from permanent genetic damage and transformation. Though Brca1 clearly participates in cellular responses to ionizing radiation (IR), conflicting conclusions have been drawn about whether Brca1 plays a direct role in cell cycle checkpoints. Normal Nbs1 function is required for the IR-induced S-phase checkpoint, but whether Nbs1 has a definitive role in the G(2)/M checkpoint has not been established. Here we show that Atm and Brca1 are required for both the S-phase and G(2) arrests induced by ionizing irradiation while Nbs1 is required only for the S-phase arrest. We also found that mutation of serine 1423 in Brca1, a target for phosphorylation by Atm, abolished the ability of Brca1 to mediate the G(2)/M checkpoint but did not affect its S-phase function. These results clarify the checkpoint roles for each of these three gene products, demonstrate that control of cell cycle arrests must now be included among the important functions of Brca1 in cellular responses to DNA damage, and suggest that Atm phosphorylation of Brca1 is required for the G(2)/M checkpoint.
556 citations
TL;DR: Differences within intragenic polymorphic markers demonstrated that at least some mutant alleles arose independently, thus eliminating a founder effect in pediatric ACC, and this inherited R337H p53 mutation represents a low-penetrance p53 allele that contributes in a tissue-specific manner to the development of pediatric ACC.
Abstract: The incidence of pediatric adrenal cortical carcinoma (ACC) in southern Brazil is 10–15 times higher than that of pediatric ACC worldwide. Because childhood ACC is associated with Li-Fraumeni syndrome, we examined the cancer history and p53 status of 36 Brazilian patients and their families. Remarkably, 35 of 36 patients had an identical germ-line point mutation of p53 encoding an R337H amino acid substitution. Differences within intragenic polymorphic markers demonstrated that at least some mutant alleles arose independently, thus eliminating a founder effect. In tumor cells, the wild-type allele was deleted, and mutant p53 protein accumulated within the nuclei. Although these features are consistent with Li-Fraumeni syndrome-associated adrenal tumors, there was no history of increased cancer incidence among family members. Therefore, this inherited R337H p53 mutation represents a low-penetrance p53 allele that contributes in a tissue-specific manner to the development of pediatric ACC.
TL;DR: Results indicate that Pten regulates neuronal size in vivo in a cell-autonomous manner and provide new insights into the etiology of Lhermitte-Duclos disease.
Abstract: Somatic inactivation of PTEN occurs in different human tumors including glioblastoma, endometrial carcinoma and prostate carcinoma. Germline mutations in PTEN result in a range of phenotypic abnormalities that occur with variable penetrance, including neurological features such as macrocephaly, seizures, ataxia and Lhermitte-Duclos disease (also described as dysplastic gangliocytoma of the cerebellum). Homozygous deletion of Pten causes embryonic lethality in mice. To investigate function in the brain, we used Cre-loxP technology to selectively inactivate Pten in specific mouse neuronal populations. Loss of Pten resulted in progressive macrocephaly and seizures. Neurons lacking Pten expressed high levels of phosphorylated Akt and showed a progressive increase in soma size without evidence of abnormal proliferation. Cerebellar abnormalities closely resembled the histopathology of human Lhermitte-Duclos disease. These results indicate that Pten regulates neuronal size in vivo in a cell-autonomous manner and provide new insights into the etiology of Lhermitte-Duclos disease.
TL;DR: The authors found that H9N2 influenza A viruses from Hong Kong live bird markets have receptor specificity similar to that of human H3N2 viruses and the neuraminidase has mutations in its hemadsorbing site.
TL;DR: A strong size confounding effect is demonstrated and the results of previous object-oriented metrics validation studies are questioned, indicating that the metrics that are expected to be validated are indeed associated with fault-proneness.
Abstract: Much effort has been devoted to the development and empirical validation of object-oriented metrics. The empirical validations performed thus far would suggest that a core set of validated metrics is close to being identified. However, none of these studies allow for the potentially confounding effect of class size. We demonstrate a strong size confounding effect and question the results of previous object-oriented metrics validation studies. We first investigated whether there is a confounding effect of class size in validation studies of object-oriented metrics and show that, based on previous work, there is reason to believe that such an effect exists. We then describe a detailed empirical methodology for identifying those effects. Finally, we perform a study on a large C++ telecommunications framework to examine if size is really a confounder. This study considered the Chidamber and Kemerer metrics and a subset of the Lorenz and Kidd metrics. The dependent variable was the incidence of a fault attributable to a field failure (fault-proneness of a class). Our findings indicate that, before controlling for size, the results are very similar to previous studies. The metrics that are expected to be validated are indeed associated with fault-proneness.
TL;DR: New studies have filled in a missing link between the yeast and mammalian pathways by identifying changes in the ER that initiate the unfolded protein response pathway.
TL;DR: Prospective virological surveillance carried out in Hong Kong between March 1998 and June 2000 on pigs imported from southeastern China provides the first evidence of interspecies transmission of avian H9N2 viruses to pigs and documents their cocirculation with contemporary human H3N2 (A/Sydney/5/97-like, Sydney97- like) viruses.
Abstract: Pigs are permissive to both human and avian influenza viruses and have been proposed to be an intermediate host for the genesis of pandemic influenza viruses through reassortment or adaptation of avian viruses. Prospective virological surveillance carried out between March 1998 and June 2000 in Hong Kong, Special Administrative Region, People's Republic of China, on pigs imported from southeastern China, provides the first evidence of interspecies transmission of avian H9N2 viruses to pigs and documents their cocirculation with contemporary human H3N2 (A/Sydney/5/97-like, Sydney97-like) viruses. All gene segments of the porcine H9N2 viruses were closely related to viruses similar to chicken/Beijing/1/94 (H9N2), duck/Hong Kong/Y280/97 (H9N2), and the descendants of the latter virus lineage. Phylogenetic analysis suggested that repeated interspecies transmission events had occurred from the avian host to pigs. The Sydney97-like (H3N2) viruses isolated from pigs were related closely to contemporary human H3N2 viruses in all gene segments and had not undergone genetic reassortment. Cocirculation of avian H9N2 and human H3N2 viruses in pigs provides an opportunity for genetic reassortment leading to the emergence of viruses with pandemic potential.
TL;DR: This chapter provides an overview of the current pharmacogenomics literature and offers insights for the potential impact of this field on the safe and effective use of medications.
Abstract: It is well recognized that most medications exhibit wide interpatient variability in their efficacy and toxicity. For many medications, these interindividual differences are due in part to polymorphisms in genes encoding drug metabolizing enzymes, drug transporters, and/or drug targets (e.g., receptors, enzymes). Pharmacogenomics is a burgeoning field aimed at elucidating the genetic basis for differences in drug efficacy and toxicity, and it uses genome-wide approaches to identify the network of genes that govern an individual's response to drug therapy. For some genetic polymorphisms (e.g., thiopurine S-methyltransferase), monogenic traits have a marked effect on pharmacokinetics (e.g., drug metabolism), such that individuals who inherit an enzyme deficiency must be treated with markedly different doses of the affected medications (e.g., 5%-10% of the standard thiopurine dose). Likewise, polymorphisms in drug targets (e.g., beta adrenergic receptor) can alter the sensitivity of patients to treatment (e.g., beta-agonists), changing the pharmacodynamics of drug response. Recognizing that most drug effects are determined by the interplay of several gene products that govern the pharmacokinetics and pharmacodynamics of medications, pharmacogenomics research aims to elucidate these polygenic determinants of drug effects. The ultimate goal is to provide new strategies for optimizing drug therapy based on each patient's genetic determinants of drug efficacy and toxicity. This chapter provides an overview of the current pharmacogenomics literature and offers insights for the potential impact of this field on the safe and effective use of medications.
TL;DR: In this paper, the authors show that capping of Fas is essential for optimal function and capping is ceramide-dependent, and they show that the presence of intact sphingolipid-enriched membrane domains may be essential for Fas capping since their disruption with cholesterol-depleting agents abrogated capping.
TL;DR: The crystal structures of Newcastle disease virus HN alone and in complex with either an inhibitor or with the β-anomer of sialic acid reveal a typical neuraminidase active site within a β-propeller fold.
Abstract: Paramyxoviruses are the main cause of respiratory disease in children. One of two viral surface glycoproteins, the hemagglutinin-neuraminidase (HN), has several functions in addition to being the major surface antigen that induces neutralizing antibodies. Here we present the crystal structures of Newcastle disease virus HN alone and in complex with either an inhibitor or with the β-anomer of sialic acid. The inhibitor complex reveals a typical neuraminidase active site within a β-propeller fold. Comparison of the structures of the two complexes reveal differences in the active site, suggesting that the catalytic site is activated by a conformational switch. This site may provide both sialic acid binding and hydrolysis functions since there is no evidence for a second sialic acid binding site in HN. Evidence for a single site with dual functions is examined and supported by mutagenesis studies. The structure provides the basis for the structure-based design of inhibitors for a range of paramyxovirus-induced diseases.
TL;DR: Enhanced hepatocellular concentrations of bile acids, due to the down-regulation of BSEP/SPGP-mediated efflux in FXR nullizygous mice, result in an alternate but apparent compensatory up- regulation of CYP3A, CYP2B, and some ABC transporters that is consistent with activation of PXR/SXR by bile acid.
TL;DR: The hypothesis that MB patients demonstrate a decline in IQ values because of an inability to acquire new skills and information at a rate comparable to their healthy same-age peers, as opposed to a loss of previously acquired information and skills is supported.
Abstract: PURPOSE: To examine two competing hypotheses relating to intellectual loss among children treated for medulloblastoma (MB): Children with MB either: (1) lose previously learned skills and information; or (2) acquire new skills and information but at a rate slower than expected compared with healthy same-age peers. PATIENTS AND METHODS: Forty-four pediatric MB patients were evaluated who were treated with postoperative radiation therapy (XRT) with or without chemotherapy. After completion of XRT, a total of 150 examinations were conducted by use of the child version of the Wechsler Intelligence Scales. These evaluations provided a measure of intellectual functioning called the estimated full-scale intelligence quotient (FSIQ). Changes in patient performance corrected for age (scaled scores) as well as the uncorrected performance (raw scores) were analyzed. RESULTS: At the time of the most recent examination, the obtained mean estimated FSIQ of 83.57 was more than one SD below expected population norms. A s...
TL;DR: The results validate the use of a genomic approach for the identification of novel microbial targets that elicit a protective immune response and may play a role in the development of improved vaccines against S. pneumoniae.
Abstract: Microbial targets for protective humoral immunity are typically surface-localized proteins and contain common sequence motifs related to their secretion or surface binding. Exploiting the whole genome sequence of the human bacterial pathogen Streptococcus pneumoniae, we identified 130 open reading frames encoding proteins with secretion motifs or similarity to predicted virulence factors. Mice were immunized with 108 of these proteins, and 6 conferred protection against disseminated S. pneumoniae infection. Flow cytometry confirmed the surface localization of several of these targets. Each of the six protective antigens showed broad strain distribution and immunogenicity during human infection. Our results validate the use of a genomic approach for the identification of novel microbial targets that elicit a protective immune response. These new antigens may play a role in the development of improved vaccines against S. pneumoniae.
TL;DR: It is shown that distinct domains of ETO contact the mSin3A and N-CoR corepressors and define two binding sites within ETO for each of these core Pressors, and that the murine homologue of MTG16, ETO-2, is a transcriptional corepressor that works through a similar but distinct mechanism.
Abstract: t(8;21) and t(16;21) create two fusion proteins, AML-1-ETO and AML-1-MTG16, respectively, which fuse the AML-1 DNA binding domain to putative transcriptional corepressors, ETO and MTG16. Here, we show that distinct domains of ETO contact the mSin3A and N-CoR corepressors and define two binding sites within ETO for each of these corepressors. In addition, of eight histone deacetylases (HDACs) tested, only the class I HDACs HDAC-1, HDAC-2, and HDAC-3 bind ETO. However, these HDACs bind ETO through different domains. We also show that the murine homologue of MTG16, ETO-2, is also a transcriptional corepressor that works through a similar but distinct mechanism. Like ETO, ETO-2 interacts with N-CoR, but ETO-2 fails to bind mSin3A. Furthermore, ETO-2 binds HDAC-1, HDAC-2, and HDAC-3 but also interacts with HDAC-6 and HDAC-8. In addition, we show that expression of AML-1-ETO causes disruption of the cell cycle in the G(1) phase. Disruption of the cell cycle required the ability of AML-1-ETO to repress transcription because a mutant of AML-1-ETO, Delta469, which removes the majority of the corepressor binding sites, had no phenotype. Moreover, treatment of AML-1-ETO-expressing cells with trichostatin A, an HDAC inhibitor, restored cell cycle control. Thus, AML-1-ETO makes distinct contacts with multiple HDACs and an HDAC inhibitor biologically inactivates this fusion protein.
TL;DR: Fusion of ALK with the clathrin heavy chain (CTLC) gene localized to 17q23 was detected in two cases of IMT, and one of these cases exhibited a 2;17 translocation in addition to other karyotypic anomalies.
Abstract: Inflammatory myofibroblastic tumor (IMT) is a rare, but distinctive mesenchymal neoplasm composed of fascicles of bland myofibroblasts admixed with a prominent inflammatory component. Genetic studies of IMTs have demonstrated chromosomal abnormalities of 2p23 and rearrangement of the anaplastic lymphoma kinase (ALK) gene locus. In a subset of IMTs, the ALK C-terminal kinase domain is fused with a tropomyosin N-terminal coiled-coil domain. In the current study, fusion of ALK with the clathrin heavy chain (CTLC) gene localized to 17q23 was detected in two cases of IMT. One of these cases exhibited a 2;17 translocation in addition to other karyotypic anomalies [46,XX,t(2;17)(p23;q23),add(16)(q24)].
Journal Article•
TL;DR: A dramatic increase in the incidence and accelerated development of medulloblastoma in mice heterozygous for Ptc that lack p53 is reported, a consequence of increased genomic instability associated with loss of p53 function that may enhance the rate of acquisition of secondary mutations.
Abstract: Brain malignancies represent the most common solid tumors in children, and they are responsible for significant mortality and morbidity. The molecular basis of the most common malignant pediatric brain tumor, medulloblastoma, is poorly understood. Mutations in several genes including the human homologue of the Drosophila segment polarity gene, patched (PTCH), the adenomatous polyposis coli gene (APC), beta-catenin, and p53 have been reported in subsets of hereditary and sporadic medulloblastoma. Inactivation of one Ptc allele in mice results in a 14% incidence of medulloblastoma. Here, we report a dramatic increase in the incidence (>95%) and accelerated development (prior to 12 weeks of age) of medulloblastoma in mice heterozygous for Ptc that lack p53. The acceleration of tumorigenesis in Ptc+/- mice is specific for loss of p53, because no change in tumor incidence was observed in Ptc+/- mice carrying a mutation in APC (Min+/-) or in Ptc+/- mice deficient in p19ARF. Thus, there is a specific interaction between p53 loss and heterozygosity of Ptc that results in medulloblastoma. This may be a consequence of increased genomic instability associated with loss of p53 function that may enhance the rate of acquisition of secondary mutations. Ptc+/- p53-/- mice provide a useful model for investigation of the molecular bases of medulloblastoma and for evaluation of the efficacy of therapeutic intervention strategies in a spontaneously arising endogenous brain tumor.
TL;DR: The site of action of isoniazid, used in the treatment of tuberculosis for 50 years, and the consumer antimicrobial agent triclosan were revealed recently to be the enoyl-ACP reductase of the type II FAS, which contrasts sharply with the type I FAS of eukaryotes.
Journal Article•
TL;DR: The current status of work in pharmacogenomics is highlighted, and strategies that hold promise for future advances in this field are addressed.
Abstract: There is great heterogeneity in the way humans respond to medications, often requiring empirical strategies to find the appropriate drug therapy for each patient (the "art" of medicine). Over the past 50 years, there has been great progress in understanding the molecular basis of drug action and in elucidating genetic determinants of disease pathogenesis and drug response. Pharmacogenomics is the burgeoning field of investigation that aims to further elucidate the inherited nature of interindividual differences in drug disposition and effects, with the ultimate goal of providing a stronger scientific basis for selecting the optimal drug therapy and dosages for each patient. These genetic insights should also lead to mechanism-based approaches to the discovery and development of new medications. This review highlights the current status of work in this field and addresses strategies that hold promise for future advances in pharmacogenomics.
TL;DR: Hemagglutinin affinity for receptors is an essential feature of influenza virus susceptibility to NA inhibitors, both in cell culture and in humans.
Abstract: Volunteers experimentally infected with influenza A/Texas/36/91 (H1N1) virus and treated with the neuraminidase (NA) inhibitor oseltamivir were monitored for the emergence of drug-resistant variants. Two (4%) of 54 resistant viruses were detected by NA inhibition assay among last-day isolates recovered from 54 drug recipients. They bore a substitution His274Tyr in the NA. Hemagglutinin (HA) variants detected in the placebo group differed from the egg-adapted inoculum virus by virtue of amino acid substitutions at residues 137, 225, or both. These variants had a higher affinity for Neu5Ac(alpha2-6)Gal-containing receptors, which are characteristic of human respiratory epithelium, than for Neu5Ac(alpha2-3)Gal-containing receptors, which are typical of chicken egg allantoic membrane. Although appearing to be more sensitive to oseltamivir in humans, the variants with increased affinity for Neu5Ac(alpha2-6)Gal receptors were less sensitive than the Neu5Ac(alpha2-3)Gal-binding variants in Madin-Darby canine kidney cells. Thus, HA affinity for receptors is an essential feature of influenza virus susceptibility to NA inhibitors, both in cell culture and in humans.
TL;DR: Rasburicase is safe and highly effective for the prophylaxis or treatment of hyperuricemia in patients with leukemia or lymphoma, and none of the patients required dialysis.
Abstract: PURPOSE: To improve the control of hyperuricemia in patients with leukemia or lymphoma, we tested a newly developed uricolytic agent, recombinant urate oxidase (SR29142; Rasburicase; Sanofi-Synthelabo, Inc, Paris, France), which catalyzes the oxidation of uric acid to allantoin, a highly water-soluble metabolite readily excreted by the kidneys. PATIENTS AND METHODS: We administered Rasburicase intravenously, at 0.15 or 0.20 mg/kg, for 5 to 7 consecutive days to 131 children, adolescents, and young adults with newly diagnosed leukemia or lymphoma, who either presented with abnormally high plasma uric acid concentrations or had large tumor cell burdens. Blood levels of uric acid, creatinine, phosphorus, and potassium were measured daily. The pharmacokinetics of Rasburicase, the urinary excretion rate of allantoin, and antibodies to Rasburicase were also studied. RESULTS: At either dosage, the recombinant enzyme produced a rapid and sharp decrease in plasma uric acid concentrations in all patients. The media...