The association between genetic polymorphisms of coproporphyrinogen oxidase and an atypical porphyrinogenic response to mercury exposure in humans

Previous studies have demonstrated highly specific urinary porphyrin profile (UPP) changes in response to mercury (Hg) exposure in animals and human subjects and have defined the biochemical etiology of this effect as selective alteration of the heme pathway enzymes, uroporphyrinogen decarboxylase (UROD), and coproporphyrinogen oxidase (CPOX) by Hg in the kidney. Ongoing validation studies in a population of dental practitioners with low-level occupational Hg exposure have demonstrated the predicted UPP change among approximately 85% of subjects. This study focused on the genetic etiology of an atypical porphyrinogenic response (APR) seen among the remaining 15% of Hg-exposed subjects, characterized by excess excretion of 4- and 5-carboxyl porphyrins and also of the atypical ketoisocoproporphyrin (KICP). Automated DNA-sequencing-based assays were developed to examine the 7 exons and flanking intron-exon boundaries of the CPOX gene. Among several polymorphisms identified, an A814C variant in exon 4 encoding a N272H substitution was found to be predominant among subjects with the APR. Studies suggest that this variant CPOX preferentially converts the upstream 5-carboxylporphyrin (5-CP) to KICP. By partially inhibiting the 5- to 4-decarboxylation step of UROD, Hg promotes 5-CP accumulation, accounting for e xcess KICP excretion and the APR in Hg-exposed subjects carrying the variant CPOX gene. This finding represents the first report of a polymorphism in a human gene that modifies the effect of Hg on a biological process. The APR might serve as a biomarker of both Hg exposure and susceptibility to Hg toxicity.     

Influence of passive lower-body heating on muscle metabolic perturbation and high-intensity exercise tolerance in humans

The purpose of this investigation was to determine the influence of heat stress on the dynamics of muscle metabolic perturbation during high-intensity exercise. Seven healthy males completed single-legged knee-extensor exercise until the limit of tolerance on two separate occasions. In a randomized order the subjects underwent 40 min of lower-body immersion in warm water at 42°C prior to exercise (HOT) or received no prior thermal manipulation (CON). Following the intervention, muscle metabolism was measured at rest and throughout exercise using (31)P-MRS. The tolerable duration of high-intensity exercise was reduced by 36% after passive heating (CON: 474?±?146 vs. HOT: 303?±?76?s; P?=?0.005). Intramuscular pH was lower over the first 60?s of exercise (CON: 7.05?±?0.02 vs. HOT: 7.00?±?0.03; P?=?0.019) in HOT compared to CON. The rate of muscle [PCr] degradation during exercise was greater in the HOT condition (CON: -0.17?±?0.08 vs. HOT: -0.25?±?0.10%?s(-1); P?=?0.006) and pH also tended to change more rapidly in HOT (P?=?0.09). Muscle [PCr] (CON: 26?±?14 vs. HOT: 29?±?10%), [Pi] (CON: 504?±?236 vs. HOT: 486?±?186%) and pH (CON: 6.84?±?0.13 vs. HOT: 6.80?±?0.14; P?>?0.05) were not statistically different at the limit of tolerance (P?>?0.05 for all comparisons). These results suggest that the reduced time-to-exhaustion during high-intensity knee-extensor exercise following lower-body heating might be related, in part, to accelerated rates of change of intramuscular [PCr] and pH towards 'critical' values that limit muscle function.     

Lower extremity revascularization based on intraoperative arteriography

The traditional approach to patients with lower extremity ischemia involves "diagnostic" arteriography performed in a radiology angiography suite prior to a separate revascularization in an operating room suite. This time-honored and staged approach has the disadvantage of an associated significant angiographic complication rate. Furthermore, in view of the accuracy of noninvasive testing and the capacity for intraoperative arteriography, this separation of diagnostic and reparative techniques may be outdated and cost-ineffective. A combination of the two in a modern operating room is a more logical approach.     

Case report: cutaneous nontuberculous mycobacterial abscesses associated with insulin injections

Nontuberculous mycobacterial (NTM) infections are on the rise and often cause skin diseases that are misdiagnosed. The authors present three cases of atypical mycobacterial infections in insulin-dependent diabetics occurring in sites of subcutaneous insulin injections. One of the patients was vitamin D deficient at the time of infection with NTM. The history and clinical presentation of the cases are presented; pathogenesis and treatment are discussed in conjunction with the correlation of mycobacterial disease susceptibility with vitamin D deficiency.     

Validity of criteria for establishing maximal O<Subscript>2</Subscript> uptake during ramp exercise tests

The incremental or ramp exercise test to the limit of tolerance has become a popular test for determination of maximal O₂ uptake However, many subjects do not evidence a definitive plateau of the -work rate relationship on this test and secondary criteria based upon respiratory exchange ratio (RER), maximal heart rate (HR_max) or blood [lactate] have been adopted to provide confidence in the measured We hypothesized that verification of using these variables is fundamentally flawed in that their use could either allow underestimation of (if, for any reason, a test were ended at a sub-maximal ), or alternatively preclude subjects from recording a valid Eight healthy male subjects completed a ramp exercise test (at 20 W/min) to the limit of tolerance on an electrically braked cycle ergometer during which pulmonary gas exchange was measured breath-by-breath and blood [lactate] was determined every 90 s. Using the most widely used criterion values of RER (1.10 and 1.15), as determined during the ramp test (4.03 ± 0.10 l/min) could be undermeasured by 27% (2.97 ± 0.24 l/min) and 16% (3.41 ± 0.15 l/min), respectively (both P < 0.05). The criteria of HR_max (age predicted HR_max ± 10 b/min) and blood [lactate] (≥8 mM) were untenable because they resulted in rejection of 3/8 and 6/8 of the subjects, most of whom (5/8) had demonstrated a plateau of at These findings provide a clear mandate for rejecting these secondary criteria as a means of validating on ramp exercise tests.     

Systematic variation of microtopography, surface chemistry and elastic modulus and the state dependent effect on endothelial cell alignment

We examined how variations in elastic modulus, surface chemistry and the height and spacing of micro-ridges interact and effect endothelial cell (EC) alignment. Specifically, we employed independent control of the surface properties in order to elucidate the relative importance of each factor. Polydimethylsiloxane elastomer (PDMSe) was fabricated with 1.5 or 5 microm tall, 5 microm spaced and 5, 10, or 20 microm wide ridge microtopographies. Elastic modulus was varied from 0.3, 1.0, 1.4, and 2.3 MPa by controlling oligomeric additives and crosslink density. Surface chemistry was left untreated, argon plasma treated, coated with fibronectin (Fn) or patterned with Fn tracks on flat PDMSe or the tops of micro-ridges. Primary porcine vascular ECs were cultured on the PDMSe substrates and nuclear form factor (NFF) was used to determine cell orientation relative to surface microtopography. Experimental results showed that microtopographical variation strongly altered EC alignment on Fn coated surfaces, but not on plasma treated surfaces. Interestingly, similar alignment was achieved with different orientation cues, either micropatterned chemistry (2D) or microtopography (3D). In total, the effect of varying one of the experimental parameters depended strongly on the state of the others, highlighting the need for multi-factor analysis of surface properties for applications where cells and tissue will contact synthetic materials.     

Potential distribution of two species in the medically important Anopheles minimus complex (Diptera: Culicidae)

Anopheles minimus Theobald (=An. minimus A) and possibly Anopheles harrisoni Harbach & Manguin (=An. minimus C) are important malaria vector species in the Minimus Complex in Southeast Asia. The distributions of these species are poorly known, although detailed information could benefit malaria vector incrimination and control. We used published collection records of these species and environmental geospatial data to construct consensus ecological niche models (ENM) of each species' potential geographic distribution. The status of the Indian taxon An. fluviatilis S as a species distinct from An. harrisoni has been debated in the literature, so we tested for differentiation in ecological niche characteristics. The predicted potential distribution of An. minimus is more southerly than that of An. harrisoni: Southeast Asia is predicted to be more suitable for An. minimus, and China and India are predicted more suitable for An. harrisoni, so An. harrisoni seems to dominate under cooler conditions. The distribution of An. minimus is more continuous than that of An. harrisoni: disjunction in the potential distribution of the latter is suggested between India and Southeast Asia Anopheles fluviatilis S occurrences are predicted within the An. harrisoni ecological potential, so we do not document ecological differentiation that might reject conspecificity. Overall, model predictions offer a synthetic view of the distribution of this species complex across the landscapes of southern and eastern Asia.     

Genomic and mutational profiling of ductal carcinomas in situ and matched adjacent invasive breast cancers reveals intra-tumour genetic heterogeneity and clonal selection

The mechanisms underlying the progression from ductal carcinoma in situ (DCIS) to invasive ductal carcinoma (IDC) of the breast are yet to be fully elucidated. Several hypotheses have been put forward to explain the progression from DCIS to IDC, including the selection of a subpopulation of cancer cells with specific genetic aberrations, and the acquisition of new genetic aberrations or non-genetic mechanisms mediated by the tumour microenvironment. To determine whether synchronously diagnosed ipsilateral DCI and IDCs have modal populations with distinct repertoires of gene copy number aberrations and mutations in common oncogenes, matched frozen samples of DCIS and IDC were retrieved from 13 patients and subjected to microarray-based comparative genomic hybridization (aCGH) and Sequenom MassARRAY (Oncocarta v 1.0 panel). Fluorescence in situ hybridization and Sanger sequencing were employed to validate the aCGH and Sequenom findings, respectively. Although the genomic profiles of matched DCI and IDCs were similar, in three of 13 matched pairs amplification of distinct loci (ie 1q41, 2q24.2, 6q22.31, 7q11.21, 8q21.2 and 9p13.3) was either restricted to, or more prevalent in, the modal population of cancer cells of one of the components. Sequenom MassARRAY identified PIK3CA mutations restricted to the DCIS component in two cases, and in a third case the frequency of the PIK3CA mutant allele reduced from 49% in the DCIS to 25% in the IDC component. Despite the genomic similarities between synchronous DCIS and IDC, our data provide strong circumstantial evidence to suggest that in some cases the progression from DCIS to IDC is driven by the selection of non-modal clones that harbour a specific repertoire of genetic aberrations.     

Impact of Nissen fundoplication on laryngopharyngeal reflux symptoms

The reliability of Nissen fundoplication for the successful treatment of laryngopharyngeal reflux (LPR) symptoms remains in question. The purpose of this study was to assess the effect that antireflux surgery has on a variety of LPR symptoms as well as the patient's perceived success of surgical intervention. A retrospective review of all antireflux surgeries between 1998 and 2008 provided a patient base for a survey in which patients ranked pre- and postoperative LPR symptoms in addition to patient satisfaction with the outcome. Of the 611 patients identified and sent the evaluation forms, 244 responses (40%) were obtained. The percentage of patients with symptom improvement after surgery were: heartburn (90.1%), regurgitation (92.6%), voice fatigue (75.2%), chronic cough (76.3%), choking episodes (83.1%), sore throat (82.9%), lump in throat (77.4%), repetitive throat clearing (72.8%), and adult-onset asthma (59.6%). Twenty per cent with repetitive throat clearing and 30 per cent with adult-onset asthma had no improvement in symptoms. Eighty-one per cent considered surgery to be a success. Comparison of those who claimed the operation was successful with those who claimed it was not revealed no difference in demographics, primary diagnosis, procedure type, or reflux symptom index score. There was a statistically significant difference in patient-perceived outcome according to the length of time since surgery. More than 88 per cent in the "not successful" group had an operation greater than 4 years prior as compared with only 70 per cent in the "successful" group (P = 0.020). Nissen fundoplication is an effective treatment for most LPR symptoms, although patients with adult-onset asthma and repetitive throat clearing appear to benefit least from surgical intervention.