<Emphasis Type="Italic">In Vitro</Emphasis> Comparison of the Effect of Stent Configuration on Wall Shear Stress Using Time-resolved Particle Image Velocimetry

Time resolved particle image velocimetry was used to measure wall shear stress (WSS) and oscillatory shear index (OSI) within a 3.0 mm diameter compliant vessel model implanted with an Abbott Vascular XIENCE V^® stent in five configurations: baseline, over-expanded, increased vessel diameter, two overlapped stents, and increased stent length. Flow through unstented vessels was also tested for comparison. Flow conditions featured a realistic coronary pressure-flow offset and reversal at average flow rates corresponding to resting (Re = 160, f = 70 bpm) and exercise conditions (Re = 300, f = 120 bpm). Comparisons revealed that the WSS was similar for all cases behind the first strut and downstream of the device, indicating that changes in configuration have little effect downstream. However, there were notable differences within each stent revealing reduced WSS values for all cases due to the stent-imposed expansion of the vessel wall (0.20–9.29 dynes/cm² for Re = 160 and d = 3.0 mm). Over-expanding the stent with a second balloon affected the alignment of the stent geometry, and led to higher WSS at the inlet and lower values at mid-stent. The overlapped stents showed disturbed flow and a WSS deficit region downstream of the overlapped region. Analysis of the longer stent showed that the WSS within the vessel recovers with distance. An overall correlation was noted between decreased WSS values and elevated OSI. Results of this study are important because decreased WSS has been implicated in endothelial cell changes and increased restenosis, and clinical research has shown that a link exists between deployment configurations and negative patient outcomes.     

Genomic Signatures of the Haarlem Lineage of Mycobacterium tuberculosis: Implications of Strain Genetic Variation in Drug and Vaccine Development

Tuberculosis is the world''s leading cause of death due to a single infectious agent, and efforts aimed at its control require a better understanding of host, environmental, and bacterial factors that govern disease outcome. Growing evidence indicates that certain Mycobacterium tuberculosis strains of distinct phylogeographic lineages elicit unique immunopathological events. However, identifying the genetic basis of these phenotypic peculiarities has proven difficult. Here we report the presence of six large sequence polymorphisms which, together with two single-nucleotide changes previously described by our group, consistently differentiate Haarlem strains from the remaining M. tuberculosis lineages. The six newly found Haarlem-specific genetic events are four deletions, which altogether involve more than 13 kb, and two intragenic insertions of the element IS6110. The absence of the genes involved in these polymorphisms could have an important physiological impact on Haarlem strains, i.e., by affecting key genes, such as Rv1354c and cyp121, which have been recently proposed as plausible drug targets. These lineage-specific polymorphisms can serve as genetic markers for the rapid PCR identification of Haarlem strains, providing a useful tool for strain surveillance and molecular epidemiology studies. Strain variability such as that described here underscores the need for the definition of a core set of essential genes in M. tuberculosis that are ubiquitously present in all circulating lineages, as a requirement in the development of effective antituberculosis drugs and vaccines.Mycobacterium tuberculosis is the causative agent of tuberculosis, the leading cause of death by a single bacterial agent in the world (36). Infection with M. tuberculosis has historically shown to result in a variety of clinical outcomes that are usually associated with host inherited susceptibility and environmental risk factors (2, 31, 32). Moreover, increasing evidence suggests that genetic variation in the tubercle bacilli also plays an important role in the outcome of the disease (4, 19, 33). Due to the absence of exchange of genetic material with a global microbial gene pool, M. tuberculosis had long been considered to have a clonal population structure. However, a significant strain-to strain genetic variation within M. tuberculosis has recently been unveiled (11, 19).Changes in neutral regions of the chromosome, such as the direct repeat (DR) locus, and in the mycobacterial interspersed repetitive units (MIRUs) are useful in epidemiological and phylogenetic analyses and in describing the most conspicuous M. tuberculosis lineages (3, 21). In addition to the variation in neutral regions, genetic polymorphisms involving coding regions have been described to occur through single-nucleotide changes and through deletion and insertion events, the latter mediated mainly by the IS6110 element (23, 30). Although these genomic alterations are thought to be among the principal sources of phenotypic variation in M. tuberculosis, the specific genomic changes that define each lineage have not yet been fully defined.There are currently six phylogeographic lineages that make up the M. tuberculosis global population (10). One is the Euro-American group, which includes all the spoligotype families predominating in the Western world, such as Haarlem, LAM, and the ill-defined T group (3). In particular, the Haarlem genotype is ubiquitous worldwide (15) and represents about 25% of the isolates in Europe, Central America, and the Caribbean, suggesting a link with the post-Columbus European colonization (8). Haarlem strains are actively transmitted in urban settings in Colombia, causing major public health problems (N. E. Correa, E. Zapata, V. Gómez, G. E. Mejia, A. Restrepo, J. Robledo, and CCITB, presented at the 107th General Meeting of the American Society for Microbiology, Toronto, Canada, 2007) and have also been responsible for a prolonged outbreak of multidrug-resistant tuberculosis in Argentina (26, 29).An intriguing question is whether M. tuberculosis strains differ in terms of pathogenic characteristics as a consequence of long-standing interactions of particular lineages with specific human populations. Animal models that take advantage of an identical genetic background, and therefore a uniform host immune response, have given insight regarding the contribution of strain genetic diversity to the outcome of the infectious process (7, 20). It is currently accepted that genetically different M. tuberculosis strains produce markedly different immunopathological events in isogenic mice (4, 18). Thus, understanding genotypic differences and mechanisms underlying infection variability and identifying specific changes or genes associated with both virulence and immunopathogenicity of the different M. tuberculosis lineages have important implications for the future effective control of tuberculosis (7, 33).In a recent bioinformatic study using multiple genome alignments of six fully sequenced M. tuberculosis strains belonging to different lineages, we showed a trend toward accumulation of a limited number of genome-specific polymorphisms preferentially associated with circulating strains and underrepresented in laboratory strains. This suggests that such polymorphisms arise as active mechanisms of adaptation to the human host (5). We speculated that some of these genome-specific polymorphisms might be common to strains of a particular lineage rather than being an exclusive property of the isolate examined. To test this, in the present study we examined whether genome-specific polymorphisms previously identified in fully sequenced strains were present in a broader group of strains and could thus represent a lineage-wide condition. In particular, we explored whether polymorphisms identified as specific to the sequenced M. tuberculosis Haarlem strain (5) were prevalent in additional members of the Haarlem lineage and absent from other lineages. In the present paper, we report the presence of eight genomic signatures highly exclusive to the M. tuberculosis Haarlem lineage that can prove important for the rapid identification of these strains and also contribute to our understanding of the genetic variations underlying phenotypic differences among the various lineages of the tubercle bacilli.     

EBNA1 sequences in Argentinean pediatric acute and latent Epstein–Barr virus infection reflect circulation of novel South American variants

Epstein–Barr virus (EBV) is related to the development of lymphomas and is also the etiological agent for infectious mononucleosis (IM). Sequence variation of the EBNA1 gene, consistently expressed in all EBV‐positive cells, has been widely studied. Based on the amino acid at codon 487 five major EBNA1 variants have been described, two closely related prototypic variants (P‐ala and P‐thr) and three variant sequences (V‐leu, V‐val, and V‐pro). Sub‐variants were then further classified based on mutations other than the originally described. While several studies proposed associations with tumors and/or anatomical compartments, others argued in favor of a geographical distribution of these variants. In the present study, EBNA1 variants in 11 pediatric patients with IM and 19 pediatric EBV lymphomas from Argentina were compared as representatives of benign and malignant infection in children, respectively. A 3‐month follow‐up study of EBNA1 variants in peripheral blood cells and in oral secretions of patients with IM was performed. A new V‐ala variant which includes five V‐ala sub‐variants and three new V‐leu sub‐variants was described. These data favor the geographical association hypothesis since no evidence for a preferential compartment distribution of EBNA1 variants and sub‐variants was found. This is the first study to characterize EBNA1 variants in pediatric patients with infection mononucleosis worldwide. J. Med. Virol. 82:1730–1738, 2010. © 2010 Wiley‐Liss, Inc.     

Human caliciviruses detected in Mexican children admitted to hospital during 1998–2000, with severe acute gastroenteritis not due to other enteropathogens

Few studies exist regarding the frequency of human caliciviruses as single etiologic agents in sporadic cases, or in outbreaks occurring in children hospitalized for acute gastroenteritis. In this study, a total of 1,129 children of <5 years of age and hospitalized due to acute diarrhea were enrolled from three main hospitals in Mexico City during a period of 3 years (March 1998 to December 2000). After analyzing all fecal samples for several enteropathogens, 396 stools that remained negative were further screened for human caliciviruses by RT‐PCR using a primer set specific to norovirus and sapovirus. Human caliciviruses were detected in 5.6% (22/396) of the children. The minimum incidence rate for 1999 were 5.3% (7/132) for 1999 and 7.8% (13/167) for 2000, since only fecal specimens that tested negative to other enteric pathogens were examined. Positive samples were further characterized using specific GI and GII primers and sequencing. Norovirus GII was detected in 19/22 samples, most of them were GII/4, while sapovirus GI/2 was detected in one sample. Associations between the presence of human calicivirus and clinical and epidemiological data revealed that diarrhea occurred with a seasonal pattern, and that children hospitalized due to human calicivirus disease scored an average of 13 ± 3.2 (SD) points on the Vesikari scale, which corresponded to severe episodes. These results highlight that human caliciviruses, by themselves, are enteropathogens of acute severe diarrhea among young Mexican children requiring hospitalization and that their detection is important in order to reduce the diagnosis gap. J. Med. Virol. 82:632–637, 2010. © 2010 Wiley‐Liss, Inc.     

Chronic graft versus host disease of oral mucosa: review of available therapies

The use of hematopoetic stem cell transplantation (HSCT) has greatly expanded in the recent years for many neoplastic and hematological disorders. Chronic graft versus host disease (cGVHD) is a major complication of allogeneic HSCT and a major cause of morbidity and mortality. Oral mucosal involvement is frequent in cGVHD and contributes significantly to the overall burden of the condition. Oral medicine professionals should be familiar with various treatment options for oral cGVHD. This review discusses treatment modalities available for the management of oral mucosal manifestations of cGVHD. Available evidence for efficacy and safety of various systemic and topical agents, including corticosteroids, calcineurin antagonists, mycophenolate mofetil, and extracorporeal photopheresis, is reviewed.     

Benfotiamine prevents macro- and microvascular endothelial dysfunction and oxidative stress following a meal rich in advanced glycation end products in individuals with type 2 diabetes

OBJECTIVE: Diabetes is characterized by marked postprandial endothelial dysfunction induced by hyperglycemia, hypertriglyceridemia, advanced glycation end products (AGEs), and dicarbonyls (e.g., methylglyoxal [MG]). In vitro hyperglycemia-induced MG formation and endothelial dysfunction could be blocked by benfotiamine, but in vivo effects of benfotiamine on postprandial endothelial dysfunction and MG synthesis have not been investigated in humans until now. RESEARCH DESIGN AND METHODS: Thirteen people with type 2 diabetes were given a heat-processed test meal with a high AGE content (HAGE; 15.100 AGE kU, 580 kcal, 54 g protein, 17 g lipids, and 48 g carbohydrates) before and after a 3-day therapy with benfotiamine (1,050 mg/day). Macrovascular flow-mediated dilatation (FMD) and microvascular reactive hyperemia, along with serum markers of endothelial disfunction (E-selectin, vascular cell adhesion molecule-1, and intracellular adhesion molecule-1), oxidative stress, AGE, and MG were measured during both test meal days after an overnight fast and then at 2, 4, and 6 h postprandially. RESULTS: The HAGE induced a maximum reactive hyperemia decrease of -60.0% after 2 h and a maximum FMD impairment of -35.1% after 4 h, without affecting endothelium-independent vasodilatation. The effects of HAGE on both FMD and reactive hyperemia were completely prevented by benfotiamine. Serum markers of endothelial dysfunction and oxidative stress, as well as AGE, increased after HAGE. These effects were significantly reduced by benfotiamine. CONCLUSIONS: Our study confirms micro- and macrovascular endothelial dysfunction accompanied by increased oxidative stress following a real-life, heat-processed, AGE-rich meal in individuals with type 2 diabetes and suggests benfotiamine as a potential treatment.     

Pleomorphic basal cell carcinoma: case reports and review

Pleomorphic basal cell carcinoma is a pathologic variant of basal cell carcinoma characterized by the presence of atypical-appearing, mononuclear or multinucleated giant cells. Including our 3 patients, a total of 52 pleomorphic basal cell carcinomas have been described in 48 individuals. The tumors usually present as a nodule on the head or neck. The nuclei of the giant tumor cells are irregularly shaped, hyperchromatic, and 2 to 10 times larger than the nuclei of the surrounding cancer cells. Atypical mitoses may be present. The pathogenesis of pleomorphic basal cell carcinoma remains to be determined; however, investigations utilizing electron microscopy, immunohistochemistry, image analysis, and flow cytometry have provided additional insight regarding the features of the giant tumor cells and the etiology of this cancer. All of these tumors are aneuploid. Although these aneuploid tumors have alarming microscopic features, their clinical course is similar to that of basal cell carcinomas without pleomorphic giant tumor cells. Therefore, appropriate therapy to ensure adequate treatment of the tumor is recommended. Our patients' pleomorphic basal cell carcinomas were successfully treated by excision using the Mohs micrographic surgical technique.     

The p.T191M mutation of the CBS gene is highly prevalent among homocystinuric patients from Spain, Portugal and South America

Classical homocystinuria is due to cystathionine -synthase (CBS) deficiency. More than 130 mutations, which differ in prevalence and severity, have been described at the CBS gene. Mutation p.I278T is very prevalent, has been found in all European countries where it has been looked for with the exception of the Iberian peninsula, and is known to respond to vitamin B₆. On the other hand, mutation p.T191M is prevalent in Spain and Portugal and does not respond to B₆. We analysed 30 pedigrees from Spain, Portugal, Colombia and Argentina, segregating for homocystinuria. The p.T191M mutation was detected in patients from all four countries and was particularly prevalent in Colombia. The number of p.T191M alleles described in this study, together with those previously published, is 71. The prevalence of p.T191M among CBS mutant alleles in the different countries was: 0.75 in Colombia, 0.52 in Spain, 0.33 in Portugal, 0.25 in Venezuela, 0.20 in Argentina and 0.14 in Brazil. Haplotype analyses suggested a double origin for this mutation. No genotype–phenotype correlation other than the B₆-nonresponsiveness could be established for the p.T191M mutation. Additionally, three new mutations, p.M173V, p.I429del and c.69_70+8del10, were found. The p.M173V was associated with a mild, B₆-responsive, phenotype.