Inflammatory bowel disease and predisposition to osteopenia

The prevalence of osteopenia in children with inflammatory bowel disease (IBD) is unknown. The effect of nutritional state, disease activity, and steroid therapy on bone mineral content (BMC) of whole body, lumbar spine, and left femoral neck measured by dual energy x ray absorptiometry in 32 children with IBD was assessed by comparison with 58 healthy local school children. Using the control data, a predicted BMC was calculated taking into account bone area, age, height, weight, and pubertal stage. The measured BMC in children with IBD was expressed as a percentage of this predicted value (% BMC). Mean (SD) % BMC was significantly reduced for the whole body and left femoral neck in the children with IBD (97.0 (4.5)% and 93.1 (12.0)% respectively, p < 0.05). Of the children with IBD, 41% had a % BMC less than 1 SD below the mean for the whole body and 47% at the femoral neck. Reduction in % BMC was associated with steroid usage but not with the magnitude of steroid dose, disease activity, or biochemical markers of bone metabolism. In conclusion, osteopenia is relatively common in childhood IBD and may be partly related to the previous use of steroids.     

Phenotypic diversity in siblings with partial androgen insensitivity syndrome

The androgen insensitivity syndrome is a heterogeneous disorder with a wide spectrum of phenotypic abnormalities, ranging from complete female to ambiguous forms that more closely resemble males. The primary abnormality is a defective androgen receptor protein due to a mutation of the androgen receptor gene. This prevents normal androgen action and thus leads to impaired virilisation. A point mutation of the androgen receptor gene affecting two siblings with partial androgen insensitivity syndrome is described. One had cliteromegaly and labial fusion and was raised as a girl, whereas the other sibling had micropenis and penoscrotal hypospadias and was raised as a boy. Both were shown to have the arginine 840 to cysteine mutation. The phenotypic variation in this family is thus dependent on factors other than abnormalities of the androgen receptor gene alone.     

Immunobiology of T helper cells and antigen-presenting cells in autoimmune thrombocytopenic purpura (ITP)

Autoimmune thrombocytopenic purpura (AITP) is a bleeding disease in which autoantibodies are directed against the individual's own platelets, resulting in enhanced Fc-mediated platelet destruction by macrophages in the reticuloendothelial system. Most research in AITP has focused on characterization of the autoantibodies, while little has been devoted to the cellular immune mechanisms leading to autoantibody production. This report summarizes the current state of the literature and argues that enhanced T helper cell/antigen-presenting cell interactions in patients with AITP are the primary stimulus for the development of antiplatelet autoantibody production. Understanding these events is important for eventually identifying disease-initiating platelet autoantigens and ultimately developing specific immunotherapies for AITP.     

Arylazido aminopropionyl ATP (ANAPP3): interaction with adenosine receptors in longitudinal smooth muscle of the guinea-pig ileum

Arylazido aminopropionyl ATP (ANAPP3), an ATP-receptor antagonist containing a photosensitive arylazido moiety coupled to the 3' hydroxyl of ATP, inhibited the twitch response of electrically stimulated ileal longitudinal muscle strips in a dose-dependent manner. These agonist responses to ANAPP3 were attenuated by the enzyme adenosine deaminase and antagonized by the adenosine receptor antagonist 8-phenyltheophylline. Schild analysis yielded similar pA2 values for ANAPP3 and adenosine suggesting a common receptor site. Several 3'-ribose-modified adenosine analogs were tested for agonist activity and found to be inactive. Results suggest that ANAPP3 interacts at the presynaptic adenosine receptor of the ileum following its metabolism to adenosine, which explains the lack of antagonism at adenosine receptors of ileal smooth muscle following photolysis of ANAPP3.     

Is the UK NICE “Reference Case” Influencing the Practice of Pediatric Quality-Adjusted Life-Year Measurement within Economic Evaluations?

ObjectivesTo report findings from a systematic review, this article sought to address two related questions. First, how has the practice of UK pediatric cost-utility analyses evolved over time, in particular how are health-related outcomes assessed and valued? Second, how do the methods compare to the limited guidance available, in particular, the National Institute for Health and Care Excellence (NICE) reference case(s)?MethodsElectronic searches of MEDLINE, Embase, and Cochrane databases were conducted for the period May 2004 to April 2012 and the Paediatric Economic Database Evaluation database for the period May 2004 to December 2010. Identified studies were screened by three independent reviewers.ResultsForty-three studies were identified, 11 of which elicit utility values through primary research. A discrepancy was identified between the methods used for outcome measurement and valuation and the methods advocated within the NICE reference case. Despite NICE recommending the use of preference-based instruments designed specifically for children, most studies that were identified had used adult measures. In fact, the measurement of quality-adjusted life-years is the aspect of economic evaluation with the greatest amount of variability and the area that most digressed from the NICE reference case.ConclusionsRecommendations stemming from the review are that all studies should specify the age range of childhood and include separate statements of perspective for costs and effects as well as the reallocation of research funding away from systematic review studies toward good quality primary research measuring utilities in children.     

Analytical and simulation methods for estimating the potential predictive ability of genetic profiling: a comparison of methods and results

Various modeling methods have been proposed to estimate the potential predictive ability of polygenic risk variants that predispose to various common diseases. However, it is unknown whether differences between them affect their conclusions on predictive ability. We reviewed input parameters, assumptions and output of the five most common methods and compared their estimates of the area under the receiver operating characteristic (ROC) curve (AUC) using hypothetical data representing effect sizes and frequencies of genetic variants, population disease risk and number of variants. To assess the accuracy of the estimated AUCs, we aimed to reproduce the AUCs of published empirical studies. All methods assumed that the combined effect of genetic variants on disease risk followed a multiplicative risk model of independent genetic effects, but they either assumed per allele, per genotype or dominant/recessive effects for the genetic variants. Modeling strategy and input parameters differed. Methods used simulation analysis or analytical formulas with effect sizes quantified by odds ratios (ORs) or relative risks. Estimated AUC values were similar for lower ORs (<1.2). When AUCs were larger (>0.7) due to variants with strong effects, differences in estimated AUCs between methods increased. The simulation methods accurately reproduced the AUC values of empirical studies, but the analytical methods did not. We conclude that despite differences in input parameters, the modeling methods estimate similar AUC for realistic values of the ORs. When one or more variants have stronger effects and AUC values are higher, the simulation methods tend to be more accurate.     

A method of limb elevation during burn surgery

Elevation of limbs during burns surgery to access the posterior aspect is routinely required. We describe a method of limb holding during burns surgery using sharp towel clips fixed to the distal phalanges of a patient's hands or feet. The limb is held in elevation using a sterile crepe bandage from the towel clips to a hook hung on a rail fixed to the theatre ceiling. We have used this technique for patients with extensive severe burns for many years with no significant damage to the nail beds or the tips of fingers and toes. This technique is convenient for surgeons as it allows easy access to hands and feet and the posterior aspects of arms and thighs. It is cost effective and safe as it spares an assistant and decreases the risk of potential occupational injury. Level of Evidence: Level V, therapeutic study.     

Laotian (delta beta) degree-thalassemia: molecular characterization of a novel deletion associated with increased production of fetal hemoglobin

We have identified and molecularly characterized a novel deletion in the beta-globin gene cluster that increases fetal hemoglobin (HbF) synthesis in a 24-year-old Laotian man who is heterozygous for this mutation. The patient is asymptomatic with a mild anemia, hypochromia, and microcytosis (Ht = 39%, MCH = 22.8 pg, MCV = 71 fl), normal levels of HbA2 (3.0%) and 11.5% HbF (G gamma A gamma ratio 60 to 40), with heterocellular distribution (52% F cells). Extensive restriction endonuclease mapping defined the 5' breakpoint within the IVS II of the delta-globin gene, between positions 775 to 781 very similar to the 5' breakpoint of the Sicilian delta beta-thalassemia. However, the 3' breakpoint was localized between two Pst I sites 4.7 kb 3' of the beta- globin gene, thus ending about 0.7 kb upstream from the 3' breakpoint of the Sicilian delta beta-thalassemia. This results in a 12.5 kb deletion of DNA. It is of interest that the 5' breakpoint of the deletion residues within an AT-rich region which has been proposed as a specific recognition signal for recombination events, while the 3' breakpoint lies within a cluster of L1 repetitive sequences (formerly known as Kpn I family repeats). The presence of the 3' breakpoints of several other deletions within this region of L1 repeats also suggests that such sequences might serve as hot spots for recombination and eventually lead to thalassemia deletions. The similarity of the 5' and 3' breakpoints of these delta beta-thalassemias underscores the putative regulatory role of the deleted and juxtaposed sequences on the expression of the gamma-globin genes in adult life.