Importance of medicine quality in achieving universal health coverage

OBJECTIVE

To assess the importance of ensuring medicine quality in order to achieve universal health coverage (UHC).

METHODS

We developed a systems map connecting medicines quality assurance systems with UHC goals to illustrate the ensuing impact of quality-assured medicines in the implementation of UHC. The association between UHC and medicine quality was further examined in the context of essential medicines in low- and middle-income countries (LMICs) by analyzing data on reported prevalence of substandard and falsified essential medicines and established indicators for UHC. Finally, we examined the health and economic savings of improving antimalarial quality in four countries in sub-Saharan Africa: the Democratic Republic of the Congo (DRC), Nigeria, Uganda, and Zambia.

FINDINGS

A systems perspective demonstrates how quality assurance of medicines supports dimensions of UHC. Across 63 LMICs, the reported prevalence of substandard and falsified essential medicines was found to be negatively associated with both an indicator for coverage of essential services (p = 0.05) and with an indicator for government effectiveness (p = 0.04). We estimated that investing in improving the quality of antimalarials by 10% would result in annual savings of $8.3 million in Zambia, $14 million in Uganda, $79 million in two DRC regions, and $598 million in Nigeria, and was more impactful compared to other potential investments we examined. Costs of substandard and falsified antimalarials per malaria case ranged from $7 to $86, while costs per death due to poor-quality antimalarials ranged from $14,000 to $72,000.

CONCLUSION

Medicines quality assurance systems play a critical role in reaching UHC goals. By ensuring the quality of essential medicines, they help deliver effective treatments that lead to less illness and result in health care savings that can be reinvested towards UHC.

Falsified and Substandard Drugs: Stopping the Pandemic

Falsified and substandard medicines are associated with tens of thousands of deaths, mainly in young children in poor countries. Poor-quality drugs exact an annual economic toll of up to US$200 billion and contribute to the increasing peril of antimicrobial resistance. The WHO has emerged recently as the global leader in the battle against poor-quality drugs, and pharmaceutical companies have increased their roles in assuring the integrity of drug supply chains. Despite advances in drug quality surveillance and detection technology, more efforts are urgently required in research, policy, and field monitoring to halt the pandemic of bad drugs. In addition to strengthening international and national pharmaceutical governance, in part by national implementation of the Model Law on Medicines and Crime, a quantifiable Sustainable Development Goal target and an international convention to insure drug quality and safety are urgent priorities.

Monitoring the quality of medicines: results from Africa, Asia, and South America

Monitoring the quality of medicines plays a crucial role in an integrated medicines quality assurance system. In a publicly available medicines quality database (MQDB), the U.S. Pharmacopeial Convention (USP) reports results of data collected from medicines quality monitoring (MQM) activities spanning the period of 2003–2013 in 17 countries of Africa, Asia, and South America. The MQDB contains information on 15,063 samples collected and tested using Minilab^® screening methods and/or pharmacopeial methods. Approximately 71% of the samples reported came from Asia, 23% from Africa, and 6% from South America. The samples collected and tested include mainly antibiotic, antimalarial, and antituberculosis medicines. A total of 848 samples, representing 5.6% of total samples, failed the quality test. The failure proportion per region was 11.5%, 10.4%, and 2.9% for South America, Africa, and Asia, respectively. Eighty-one counterfeit medicines were reported, 86.4% of which were found in Asia and 13.6% in Africa. Additional analysis of the data shows the distribution of poor-quality medicines per region and by therapeutic indication as well as possible trends of counterfeit medicines.

Assessment of the performance of a handheld Raman device for potential use as a screening tool in evaluating medicines quality

The TruScan(®) handheld Raman device is used for testing finished pharmaceutical products in the field to detect counterfeit and substandard medicines. Present work reports on the device's ability to discriminate between a specific product and similar products from different manufacturers, unrelated medicines, and medicines with different strengths. This investigation evaluated its ability to differentiate between similar drug products of similar or different strengths, focusing on the specificity and precision of the testing. First, several units of the same medicine's dosage form were compared; then comparisons were made between unrelated products, similar products, and products with different strengths. The six pharmaceutical products used in testing were from commonly used analgesic, antimalarial, and antidiarrheal medicines. The results showed that the performance of the TruScan(®) device depends on the nature and the strength of the dosage form tested; while the device could be suitable for authentication of some finished pharmaceutical products and, hence, could be used to detect some counterfeit medicines, it could not be used to detect substandard medicines. Careful consideration should be given when using the device as a screening tool for counterfeit medicines.

Wnt pathway in pulmonary fibrosis in the bleomycin mouse model

BACKGROUND

The Wnt/beta-catenin signaling pathway plays an important role in regulating cellular differentiation, proliferation, and polarity.

METHODS

We used bleomycin to induce lung fibrosis in a transgenic Wnt reporter mouse to characterize the expression pattern of cyclin D1, MMP-7, and TGF-beta in conjunction with the Wnt/beta-catenin signaling pathway. LacZ expression reveals the Wnt/beta-catenin signaling pathway through the activated (nuclear) beta-catenin and coactivation of LEF/TCF transcription factors. X-gal staining and immunohistochemical staining of beta-catenin, cyclin D1, MMP-7, and TGF-beta were assessed after bleomycin administration.

RESULTS

We observed LacZ expression in bronchiolar proliferative lesions and the epithelium in remodeled cystic and fibrotic areas at both 1 and 3 weeks. Nuclear beta-catenin staining was prominent in epithelial cells of remodeled and fibrotic areas at 3 weeks. MMP-7 was faint in basement membranes of airways and matrix zones in fibrotic areas at 3 weeks. Cyclin D1 was observed in alveolar macrophages (AM), alveolar epithelium, and fibrotic areas consistent with rapid cell turnover in these areas at both 1 and 3 weeks. TGF-beta was faintly staining in alveolar macrophages and epithelial cells at 3 weeks.

CONCLUSION

The Wnt/beta-catenin pathway is activated in bleomycin-induced lung fibrosis, and downstream genes were localized in AM, alveolar epithelium, and interstitium.

Chemokines induce matrix metalloproteinase-2 through activation of epidermal growth factor receptor in arterial smooth muscle cells

OBJECTIVE

Matrix metalloproteinases (MMP) are critical to smooth muscle cell (SMC) migration in vivo. MMP-2 dysregulation has been implicated in the pathogenesis of abnormal arterial remodeling, aneurysm formation, and atherosclerotic plaque structure and stability. The chemokine receptors CCR3 and CXCR4 are present and functional on SMC and are up-regulated in vascular diseases such as atherosclerosis. We sought to determine a potential mechanism for chemokine receptor-mediated effects on the vasculature by asking whether the chemokines eotaxin (CCL11), the ligand for CCR3, and stromal cell-derived cell factor (SDF-1, CXCL12), the ligand for CXCR4, induce MMP-2 in SMC. Studies were then performed to define the signaling pathways involved.

METHODS AND RESULTS

As determined by RT-PCR, Western blotting and zymography, SDF-1 and eotaxin induce MMP-2 mRNA, protein, and activity in SMC. An anti-CCR3 antibody and a CXCR4 antagonist blocked proMMP-2 induction by SDF-1 and eotaxin, the respective ligands for the chemokine receptors CXCR4 and CCR3, suggesting that the inductions by these chemokines are receptor-mediated. Receptor cross-talk between G-protein-coupled receptors (GPCR) and the epidermal growth factor receptor (EGFR) is a method of expanding the GPCRs' signaling repertoire. We demonstrate, for the first time to our knowledge, that in SMC, chemokine induction of proMMP-2 is dependent on activation of the EGFR. Interestingly, by blocking the ligand binding domain of EGFR, we demonstrate that activation of EGFR by SDF-1 and eotaxin occurs through different cellular pathways.

CONCLUSION

The pro-inflammatory chemokines eotaxin and SDF induce proMMP-2 activation of EGFR through two different pathways. SDF and eotaxin, as regulators of proMMP-2 expression and by engaging in receptor cross-talk, may play critical roles in atherosclerosis, restenosis, and plaque rupture. These ligands and their respective receptors, CXCR4 and CCR3, therefore may serve as future potential therapeutic targets.

cDNA microarray analysis of HBV transgenic mouse liver identifies genes in lipid biosynthetic and growth control pathways affected by HBV

Hepatitis B virus (HBV) transgenic mice that replicate HBV in the liver generally do not exhibit gross liver pathology, while maintaining a high level (10(7) or greater) of viral titer in the blood. We have used this model to determine the minimum effects of HBV replication in the liver on cellular gene transcription, using cDNA microarrays. cDNA microarray data from sets of HBV versus control cDNA microarrays revealed a very small impact of HBV on the cellular transcriptome. After deletion of genes that were variable in control cDNA microarrays and applying significance analysis of microarrays (SAM), an application to detect statistically significantly regulated genes, we identified 18 upregulated genes and 14 downregulated genes. Most of the regulated genes show a change in expression with respect to control of less than 40% in either direction, demonstrating small effects of HBV. The largest functional category for upregulated genes was lipid biosynthesis, in which ATP citrate lyase, fatty acid synthase, sterol regulatory element binding factor 2, and retinol binding protein 1 were all upregulated. The most strongly downregulated genes were in the cytochrome p450 group, particularly p450, 4a14. Several growth regulatory genes including cyclin D1, IGF binding protein 3, and PCNA were moderately upregulated. These data are the first to specifically identify enzymes involved in fatty acid and NADPH-electron transport pathways that are altered by the presence of HBV. The data also demonstrates that HBV is well adapted to non-cytopathic replication in hepatocytes. Cellular genes expected to be affected by viral secretion from membranes are clearly upregulated, and upregulation of growth regulatory genes may facilitate replacement of dying hepatocytes during persistent infection.

In vivo addition of poly(A) tail and AU-rich sequences to the 3' terminus of the Sindbis virus RNA genome: a novel 3'-end repair pathway

Alphaviruses are mosquito-transmitted RNA viruses that cause important diseases in both humans and livestock. Sindbis virus (SIN), the type species of the alphavirus genus, carries a 11.7-kb positive-sense RNA genome which is capped at its 5' end and polyadenylated at its 3' end. The 3' nontranslated region (3'NTR) of the SIN genome carries many AU-rich motifs, including a 19-nucleotide (nt) conserved element (3'CSE) and a poly(A) tail. This 3'CSE and the adjoining poly(A) tail are believed to regulate the synthesis of negative-sense RNA and genome replication in vivo. We have recently demonstrated that the SIN genome lacking the poly(A) tail was infectious and that de novo polyadenylation could occur in vivo (K. R. Hill, M. Hajjou, J. Hu, and R. Raju, J. Virol. 71:2693-2704, 1997). Here, we demonstrate that the 3'-terminal 29-nt region of the SIN genome carries a signal for possible cytoplasmic polyadenylation. To further investigate the polyadenylation signals within the 3'NTR, we generated a battery of mutant genomes with mutations in the 3'NTR and tested their ability to generate infectious virus and undergo 3' polyadenylation in vivo. Engineered SIN genomes with terminal deletions within the 19-nt 3'CSE were infectious and regained their poly(A) tail. Also, a SIN genome carrying the poly(A) tail but lacking a part or the entire 19-nt 3'CSE was also infectious. Sequence analysis of viruses generated from these engineered SIN genomes demonstrated the addition of a variety of AU-rich sequence motifs just adjacent to the poly(A) tail. The addition of AU-rich motifs to the mutant SIN genomes appears to require the presence of a significant portion of the 3'NTR. These results indicate the ability of alphavirus RNAs to undergo 3' repair and the existence of a pathway for the addition of AU-rich sequences and a poly(A) tail to their 3' end in the infected host cell. Most importantly, these results indicate the ability of alphavirus replication machinery to use a multitude of AU-rich RNA sequences abutted by a poly(A) motif as promoters for negative-sense RNA synthesis and genome replication in vivo. The possible roles of cytoplasmic polyadenylation machinery, terminal transferase-like enzymes, and the viral polymerase in the terminal repair processes are discussed.

RNA-RNA recombination in Sindbis virus: roles of the 3' conserved motif, poly(A) tail, and nonviral sequences of template RNAs in polymerase recognition and template switching

Sindbis virus (SIN), a mosquito-transmitted animal RNA virus, carries a 11.7-kb positive-sense RNA genome which is capped and polyadenylated. We recently reported that the SIN RNA-dependent RNA polymerase (RdRp) could initiate negative-strand RNA synthesis from a 0.3-kb 3'-coterminal SIN RNA fragment and undergo template switching in vivo (M. Hajjou, K. R. Hill, S. V. Subramaniam, J. Y. Hu, and R. Raju, J. Virol. 70:5153-5164, 1996). To identify and characterize the viral and nonviral sequences which regulate SIN RNA synthesis and recombination, a series of SIN RNAs carrying altered 3' ends were tested for the ability to produce infectious virus or to support recombination in BHK cells. The major findings of this report are as follows: (i) the 3'-terminal 20-nucleotides (nt) sequence along with the abutting poly(A) tail of the SIN genome fully supports negative-strand synthesis, genome replication, and template switching; (ii) a full-length SIN RNA carrying the 3'-terminal 24 nt but lacking the poly(A) tail is noninfectious; (iii) SIN RNAs which carry 3' 64 nt or more without the poly(A) tail are infectious and regain their poly(A) tail in vivo; (iv) donor templates lacking the poly(A) tail do not support template switching; (v) full-length SIN RNAs lacking the poly(A) tail but carrying 3' nonviral extensions, although debilitated to begin with, evolve into rapidly growing poly(A)-carrying mutants; (vi) poly(A) or poly(U) motifs positioned internally within the acceptor templates, in the absence of other promoter elements within the vicinity, do not induce the jumping polymerase to reinitiate at these sites; and (vii) the junction site selection on donor templates occurs independently of the sequences around the acceptor sites. In addition to furthering our understanding of RNA recombination, these studies give interesting clues as to how the alphavirus polymerase interacts with its 3' promoter elements of genomic RNA and nonreplicative RNAs. This is the first report that an in vitro-synthesized alphavirus RNA lacking a poly(A) tail can initiate infection and produce 3' polyadenylated viral genome in vivo.

Nonhomologous RNA-RNA recombination events at the 3' nontranslated region of the Sindbis virus genome: hot spots and utilization of nonviral sequences

The mechanism of RNA-RNA recombination at the 3' nontranslated region (3'NTR) of the Sindbis virus (SIN) genome was studied by using nonreplicative RNA precursors. The 11.7-kb SIN genome was transcribed in vitro as two nonoverlapping RNA fragments. RNA-1 contained the entire 11.4-kb protein coding sequence of SIN and also carried an additional 1.8-kb nonviral sequence at its 3' end. RNA-2 carried the remaining 0.26 or 0.3 kb of the SIN genome containing the 3'NTR. Transfection of these two fragments into BHK cells resulted in vivo RNA-RNA recombination and release of infectious SIN recombinants. Eighteen plaque-purified recombinant viruses were sequenced to precisely map the RNA-RNA crossover sites at the 3'NTR. Sixteen of the 18 recombinants were found to be genetically heterogeneous at the 3'NTR. Two major clustered sites within the 3'NTR of RNA-2 were found to be fused to multiple locations on the nonviral sequence of RNA-1, resulting in insertions of 10 to 1,085 nucleotides at the 3'NTR. Sequence analysis of crossover sites suggested only limited homology and heteroduplex-forming capability between substrate RNAs. Analysis of additional 23 recombinant viruses generated by mutagenized donor and acceptor templates supports the occurrence of recombination hot spots on donor templates. Introduction of a 17-nucleotide rudimentary replicase recognition signal in the acceptor template alone did not induce the polymerase to reinitiate at the 17-nucleotide signal. Interestingly, deletion of a 24-nucleotide hot spot locus on the donor template abolished crossover events at one of the two sites and allowed the polymerase to reinitiate at the 17-nucleotide replicase recognition signal inserted at the acceptor template. The possible roles of RNA-protein and RNA-RNA interactions in the differential regulation of apparent pausing, template selection, and reinitiation are discussed.

Genesis of Sindbis virus by in vivo recombination of nonreplicative RNA precursors

Genetically engineered RNA transcripts coding for various Sindbis virus (SIN) genes were used to study structure and sequence requirements of RNA recombination in BHK cells. Three different groups of RNA transcripts were made: (i) RNAs which retain the ability to replicate and which carry sequences coding for either viral polymerase or viral structural proteins; (ii) RNAs which lack the complete 3' end of the SIN genome and thus are incapable of replicating; and (iii) RNAs which lack the complete 5' end of the SIN genome and also are incapable of replicating. BHK cells were transfected with specific combinations of these precursor RNAs, and virus production and RNA synthetic abilities of the released virus were determined. We demonstrate in vivo generation of infectious SIN by fusion of (i) replicative RNAs to nonreplicative RNAs and (ii) two nonreplicative RNA precursors. Both homologous and nonhomologous types of recombinations were observed. In the homologous type of recombination, a 694-nucleotide overlap at the crossover region of the first pair of precursors resulted in the addition of an A residue converting the UAG stop codon of nonstructural protein P4 to a UAA stop codon. In the nonhomologous type of recombination, the crossover sites contained deletion of up to 76 nucleotides from one of the precursors and complete preservation of junction sequence from the other precursor. This is also the first report that a cytoplasmic RNA virus can be generated from biologically nonreplicative RNA precursors. These results have implications for initiation of viral RNA synthesis and recombination between RNA viral genomes in general. We favor template switching as a mechanism for the fusion events described here and suggest inclusion of polymerase scanning of diverse nonreplicative RNAs as an inherent feature of the copy choice model of RNA recombination. Very importantly, the facile nature of RNA recombination occurring between nonreplicative RNA precursors should speed up the production and analysis of targeted mutants of SIN and possibly other RNA viruses.

Catalytic site studies on tuna (Thunnus albacares) pyloric caeca aminopeptidase

Tuna pyloric caeca aminopeptidase (tAP) is a glycosylated zinc-metalloenzyme containing apparently two identical subunits. The enzyme is reversibly inhibited in a time-dependent manner by amastatin. Slow development of tAP inhibition by this inhibitor could be demonstrated. Dissociation of the complex of tAP with amastatin is also slow. Two molar equivalents of the inhibitor are bound by the enzyme suggesting the presence of one catalytic site in each subunit. Chemical modification of tAP with 1-cyclohexyl-3-(2-morpholinoethyl) carbonyl-metho-p-toluene sulfonate and N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinone revealed the presence of essential acidic amino acid residues probably located at the active site. Compatible with the presence of arginine and tyrosine residues at the catalytic site of most metalloproteinases, tAP is reversibly inhibited by phenylglyoxal and inactivated by tetranitromethane in a time-dependent fashion. The rate of inhibition by these modifiers could be significantly decreased if the enzyme was previously treated with amastatin suggesting that the modified amino acid residues are located at the catalytic site. Diethylpyrocarbonate did not affect the activity of both native and zinc-depleted tAP suggesting that histidine is not involved in the zinc-ligand formation.

Purification and characterization of an aminopeptidase from tuna (Thunnus albacares) pyloric caeca

An aminopeptidase was purified from a water soluble fraction of tuna pyloric caeca by heat treatment, Zn2+ fractionation, ion exchange on a DEAE cellulose column, gel filtration on Fractogel TSK-55, and immobilized metal ion affinity chromatography (IMAC) on IDA(Cu2+/Zn2+)-Sepharose 6B. The molecular mass of the enzyme was estimated to be 150,000 on Sephacryl S-300 HR, and was found to be near 72,000 by SDS-PAGE. The aminopeptidase, which is a glycoprotein rich in acidic amino acids, is optimally active at pH 8.8 and 65 degrees C. The enzyme activity was not affected by Mg2+, Zn2+, Ca2+, Mn2+, Co2+, PMSF, iPr2FP, 4-hydroxymercuribenzoic acid, iodoacetamide, puromycin, and cysteine but it was strongly inhibited by metal chelators (EDTA and o-phenanthroline), amastatin, Hg2+, Cd2+, and Cu2+. The enzyme was also inhibited by some L-amino acids. Kinetic parameters of the enzyme were determined with some aminoacyl-p-nitroanilides and aminoacyl-beta-naphthylamides. L-Alanine-p-nitroanilide and L-alanine-beta-naphthylamide were hydrolysed most rapidly while the highest hydrolytic coefficient (kcat/Km) value was obtained with L-methionine-p-nitroanilide. The apoaminopeptidase was prepared and reconstitution of an active enzyme was carried out using metal chelating interaction chromatography on an IDA-Sepharose 6B column charged with a metal ion. Full activity was restored with Zn2+, Co2+, Cu2+ and Al3+. Zn(2+)-Enzyme was the most thermostable form of the aminopeptidase. Reversal inhibition by Cu2+ and Cd2+ was also examined. When the aminopeptidase was partially deglycosylated by a treatment with N-glycosidase F some of its physical properties differed from that of the native enzyme: its electrophoretic mobility was reduced and its stability to denaturation by SDS and by ionic strength were lower than those of the untreated enzyme. All together, our results indicate that the tuna pyloric caeca aminopeptidase is distinct from the peptide hydrolases characterized in the literature.