Evaluation of stool antigen test for Helicobacter pylori infection in asymptomatic children from a developing country using 13C-urea breath test as a standard

OBJECTIVE: Prevalence of asymptomatic Helicobacter pylori infection is very high in infants and children in developing countries. C urea breath test (UBT) is a reliable non-invasive diagnostic test for H. pylori infection in children that avoids invasive endoscopy. We compared a newly introduced H. pylori stool antigen test (with a high sensitivity and specificity in symptomatic children) with UBT in asymptomatic children mostly 1-5 years old, from a population with a high prevalence of infection. METHOD: Eighty six asymptomatic children (42 boys and 44 girls) were tested for H. pylori infection using the UBT and a stool antigen test (HpSA) based on a sandwich enzyme immunoassay for antigen detection. RESULTS: Forty five of the eighty-six (52.3%) children tested positive for H. pylori using the breath test. In 34 of these forty-five children, H. pylori antigen was detected in stool (sensitivity = 75.6%, 95% CI = 63 to 88%). Of the 50 of 86 (58%) children positive by HpSA test, 34 were positive for breath test. Of the 41 children with negative UBT test 25 were negative for stool antigen test (specificity = 61%, 95% CI = 46 to 76%). CONCLUSION: The sensitivity and specificity of the new stool antigen test are lower in asymptomatic children with high H. pylori prevalence rate compared to those reported for children with gastrointestinal symptoms. Its usefulness is limited for diagnosis in an asymptomatic child with H. pylori infection.     

A modular microfluidic architecture for integrated biochemical analysis

Microfluidic laboratory-on-a-chip (LOC) systems based on a modular architecture are presented. The architecture is conceptualized on two levels: a single-chip level and a multiple-chip module (MCM) system level. At the individual chip level, a multilayer approach segregates components belonging to two fundamental categories: passive fluidic components (channels and reaction chambers) and active electromechanical control structures (sensors and actuators). This distinction is explicitly made to simplify the development process and minimize cost. Components belonging to these two categories are built separately on different physical layers and can communicate fluidically via cross-layer interconnects. The chip that hosts the electromechanical control structures is called the microfluidic breadboard (FBB). A single LOC module is constructed by attaching a chip comprised of a custom arrangement of fluid routing channels and reactors (passive chip) to the FBB. Many different LOC functions can be achieved by using different passive chips on an FBB with a standard resource configuration. Multiple modules can be interconnected to form a larger LOC system (MCM level). We demonstrated the utility of this architecture by developing systems for two separate biochemical applications: one for detection of protein markers of cancer and another for detection of metal ions. In the first case, free prostate-specific antigen was detected at 500 aM concentration by using a nanoparticle-based bio-bar-code protocol on a parallel MCM system. In the second case, we used a DNAzyme-based biosensor to identify the presence of Pb(2+) (lead) at a sensitivity of 500 nM in <1 nl of solution.     

A partial atomic structure for the flagellar hook of Salmonella typhimurium

The axial proteins of the bacterial flagellum function as a drive shaft, universal joint, and propeller driven by the flagellar rotary motor; they also form the putative protein export channel. The N- and C-terminal sequences of the eight axial proteins were predicted to form interlocking alpha-domains generating an axial tube. We report on an approximately 1-nm resolution map of the hook from Salmonella typhimurium, which reveals such a tube made from interdigitated, 1-nm rod-like densities similar to those seen in maps of the filament. Atomic models for the two outer domains of the hook subunit were docked into the corresponding outermost features of the map. The N and C termini of the hook subunit fragment are positioned next to each other and face toward the axis of the hook. The placement of these termini would permit the residues missing in the fragment to form the rod-like features that form the core domain of the hook. We also fit the hook atomic model to an approximately 2-nm resolution map of the hook from Caulobacter crescentus. The hook protein sequence from C. crescentus is largely homologous to that of S. typhimurium except for a large insertion (20 kDa). According to difference maps and our fitting, this insertion is found on the outer surface of the hook, consistent with our modeling of the hook.     

New symptomatic vertebral compression fractures within a year following vertebroplasty in osteoporotic women

BACKGROUND AND PURPOSE: Percutaneous vertebroplasty has been performed in the United States in an increasing volume since the mid-1990s. The purpose of this study is to analyze the risk of a new symptomatic vertebral compression fractures within 1 year of having an acute/subacute fracture treated with vertebroplasty. METHODS: A retrospective analysis was performed in which 253 female patients were found to have acute/subacute vertebral compression fractures secondary to osteoporosis treated with percutaneous vertebroplasty. Occurrences of new symptomatic vertebral compression fractures were recorded for a year following initial vertebroplasty. RESULTS: Fifty-five patients (21.7%) of the 253 osteoporotic women with one or more initial fractures experienced a new symptomatic vertebral compression fracture within 1 year. CONCLUSION: Roughly one-fifth of osteoporotic women with acute/subacute fracture treated with vertebroplasty will have a subsequent fracture within 1 year.     

Intradiskal extravasation with low-volume cement filling in percutaneous vertebroplasty

BACKGROUND AND PURPOSE: Adjacent fracture formation after percutaneous vertebroplasty has been reported in literature. The purpose of this study was to determine whether intervertebral disk extravasation is related to adjacent fracture formation in low-volume cement-filling vertebroplasty. METHODS: A retrospective analysis of 308 patients having vertebroplasty was undertaken. Anteroposterior and lateral procedural fluoroscopy radiographs were analyzed for mild, moderate, or severe disk extravasation. Symptomatic refracture location relative to the presence or absence of extravasation was analyzed on follow-up fluoroscopy radiographs. RESULTS: Of the 308 patients in the study, 81 patients had disk extravasation at a total of 85 vertebral levels; 40 levels had mild extravasation, 38 levels had moderate extravasation, and 7 had severe extravasation. Of the 40 levels with mild extravasation, 6 new adjacent fractures occurred next to the disk leakage. Of the 38 with moderate extravasation, 6 new adjacent fractures occurred. Of the 7 levels of severe extravasation, only one new adjacent fracture occurred. Hence, a total of 13 adjacent fractures occurred next to disk extravasation; 13 nonadjacent fractures also occurred in the patients with disk extravasation. In the patients without disk extravasation, 28 adjacent and 24 nonadjacent subsequent fractures occurred. The average available cement volumes injected into vertebral bodies causing disk leakage ranged from 4.78 to 5.60 mL. CONCLUSIONS: With low-volume cement-filling percutaneous vertebroplasty, we cannot conclude (level of significance alpha = .05) that for patients who have a new fracture there is significance between the location of the fracture and the occurrence of disk extravasation.     

Fetal MRI : reviewing the history, indications, technique, safety and drawbacks

The ultrasound is undoubtedly the first-line diagnostic examination to identify prenatal congenital abnormalities. Fetal-MRI (FMRI) is a non-invasive, fast, highly informative examination that can shed immense information on anatomical abnormalities and affect decision-making. If, in spite of a significant pathology, the parents insist on continuing with the pregnancy, help of other interdisciplinary specialities can be sought for postnatal care. The article briefly describes different aspects of FMRI.