The nonsense mutation stop+4 model correlates with motor changes in Duchenne muscular dystrophy

The aim was to assess 3-year longitudinal data using 6MWT in 26 ambulant boys affected by DMD carrying nonsense mutations and to compare their results to other small mutations. We also wished to establish, within the nonsense mutations group, patterns of change according to several variables. Patients with nonsense mutations were categorized according to the stop codon type newly created by the mutation and also including the adjacent 5′ (upstream) and 3′ (downstream) nucleotides. No significant difference was found between nonsense mutations and other small mutations (p > 0.05) on the 6MWT. Within the nonsense mutations group, there was no difference in 6MWT when the patients were subdivided according to: Type of stop codon, frame status of exons involved, protein domain affected. In contrast, there was a difference when the stop codon together with the 3′ adjacent nucleotide (“stop+4 model”) was considered (p < 0.05) with patients with stop codon TGA and 3′ adjacent nucleotide G (TGAG) having a more rapid decline. Our finding suggest that the stop+4 model may help in predicting functional changes. This data will be useful at the time of interpreting the long term follow up of patients treated with Ataluren that are becoming increasingly available.     

Internet Addiction Test (IAT): Which is the Best Factorial Solution?

Background

The Internet Addiction Test (IAT) by Kimberly Young is one of the most utilized diagnostic instruments for Internet addiction. Although many studies have documented psychometric properties of the IAT, consensus on the optimal overall structure of the instrument has yet to emerge since previous analyses yielded markedly different factor analytic results.

Objective

The objective of this study was to evaluate the psychometric properties of the Italian version of the IAT, specifically testing the factor structure stability across cultures.

Methods

In order to determine the dimensional structure underlying the questionnaire, both exploratory and confirmatory factor analyses were performed. The reliability of the questionnaire was computed by the Cronbach alpha coefficient.

Results

Data analyses were conducted on a sample of 485 college students (32.3%, 157/485 males and 67.7%, 328/485 females) with a mean age of 24.05 years (SD 7.3, range 17-47). Results showed 176/485 (36.3%) participants with IAT score from 40 to 69, revealing excessive Internet use, and 11/485 (1.9%) participants with IAT score from 70 to 100, suggesting significant problems because of Internet use. The IAT Italian version showed good psychometric properties, in terms of internal consistency and factorial validity. Alpha values were satisfactory for both the one-factor solution (Cronbach alpha=.91), and the two-factor solution (Cronbach alpha=.88 and Cronbach alpha=.79). The one-factor solution comprised 20 items, explaining 36.18% of the variance. The two-factor solution, accounting for 42.15% of the variance, showed 11 items loading on Factor 1 (Emotional and Cognitive Preoccupation with the Internet) and 7 items on Factor 2 (Loss of Control and Interference with Daily Life). Goodness-of-fit indexes (NNFI: Non-Normed Fit Index; CFI: Comparative Fit Index; RMSEA: Root Mean Square Error of Approximation; SRMR: Standardized Root Mean Square Residual) from confirmatory factor analyses conducted on a random half subsample of participants (n=243) were satisfactory in both factorial solutions: two-factor model (χ² ₁₃₂= 354.17, P<.001, χ²/df=2.68, NNFI=.99, CFI=.99, RMSEA=.02 [90% CI 0.000-0.038], and SRMR=.07), and one-factor model (χ² ₁₆₉=483.79, P<.001, χ²/df=2.86, NNFI=.98, CFI=.99, RMSEA=.02 [90% CI 0.000-0.039], and SRMR=.07).

Conclusions

Our study was aimed at determining the most parsimonious and veridical representation of the structure of Internet addiction as measured by the IAT. Based on our findings, support was provided for both single and two-factor models, with slightly strong support for the bidimensionality of the instrument. Given the inconsistency of the factor analytic literature of the IAT, researchers should exercise caution when using the instrument, dividing the scale into factors or subscales. Additional research examining the cross-cultural stability of factor solutions is still needed.     

High-dose vincristine, fractionated total-body irradiation and cyclophosphamide as conditioning regimen in allogeneic and autologous bone marrow transplantation for childhood acute lymphoblastic leukaemia in second remission: a 7-year Italian multicentre study

We investigated the feasibility and efficacy of high-dose vincristine (4 mg/m² over 4 d) combined with fractionated total body irradiation (F-TBI) (200 cGyx2 over 3 d) and cyclophosphamide (60 mg/kg for 2 d) as a preparative regimen in allogeneic (AlloBMT) and autologous (ABMT) bone marrow transplantation for 75 consecutive children (median age at transplant 8-5 years) with acute lymphoblastic leukaemia in second complete remission (CR). Median duration of first CR was 26 and 25 months in the AlloBMT and ABMT group, respectively. Of the 46 patients who underwent AlloBMT, 33 had isolated or combined marrow relapse and 13 isolated extramedullary relapse. Of the 29 patients given ABMT, 23 had preBMT isolated or combined marrow relapse and six isolated extramedullary relapse. 44/75 patients are alive and in CR at a median follow-up of 35 months (range 10-90 months). Seven children given AlloBMT (15.8%) and two given ABMT (7%) died from transplant-related causes. No major early organ toxicity, including vincristine-related toxicity, was recorded. The overall 3-year EFS estimate (95% CL) was 53.8% (42-66%): in particular, 58.2% (40-76%) for AlloBMT and 27.6% (9-46%) for ABMT patients who experienced a marrow relapse before transplant. The overall 3-year relapse rate estimate (95% CL) was 39.2% (27-51%): in particular, 30.1% (12-49%) in the AlloBMT group and 72% (54-91%) in the ABMT group ( P < 0.01) who presented a preBMT isolated or combined marrow relapse. We conclude that the conditioning regimen with high-dose vincristine combined with cyclophosphamide and F-TBI is feasible and promising, although its therapeutic advantage should be tested in larger series of patients enrolled in randomized studies.     

Bradykinin and angiotensin-converting enzyme inhibition in cardioprotection

OBJECTIVES:

To show that angiotensin-converting enzyme (ACE) inhibition potentiates subthreshold ischemic preconditioning (IPC) via the elevation of bradykinin activity, leading to a fully delayed cardioprotective response.

METHODS:

On day 1 of the experiment, pigs were subjected to sham (group 1, controls) or IPC protocols. In groups 2 and 3, 4×5 min and 2×2 min of IPC, respectively, were elicited by occluding the left anterior descending coronary artery with percutaneous transluminal coronary angioplasty inflatable balloon catheter. Group 4 was subjected to the ACE inhibitor perindoprilate only. In group 5, the pigs were pretreated with perindoprilate (0.06 mg/kg) and then subjected to 2×2 min IPC. In group 6, intracoronary HOE 140 (a selective bradykinin B₂ receptor antagonist) was added before the perindoprilateaugmented subthreshold (2×2 min) PC stimulus. On the second day, all animals underwent 40 min left anterior descending coronary artery ligation and 3 h reperfusion, followed by infarct size analysis using triphenyl tetrazolium chloride staining.

RESULTS:

The rates of infarct size and risk zone were the following in the experimental groups: group 1, 42.8%; group 2,19.5% (P<0.05); group 3, ischemia/reperfusion (I/R) 33.4%; group 4, I/R 18.4% (P<0.05); group 5, I/R 31.2%; and group 6, I/R 36.3%. A significant increase of nuclear factor kappa B activation in groups 2 and 4 was seen.

CONCLUSIONS:

Results confirm that ACE inhibitors do not give total pharmacological IPC, but they enhance the induction effect of small ischemic insults, which raises the ischemic tolerance of myocardium. It was determined that enhanced bradykinin activity leads to downstream nuclear factor kappa B activation in this model.     

The chance finding at multislice computed tomography coronary angiography of myocardial bridging

Myocardial bridging is present when a segment of a major epicardial coronary artery, the ‘tunnelled artery’, runs intramurally through the myocardium. With each systole, the coronary artery is compressed. The pathophysiology of myocardial bridging is incompletely understood. With each systole, the coronary artery is compressed. Moreover, intravascular ultrasound analysis revealed a delayed relaxation after systolic compression, which may extend significantly into diastole. This explains both the impaired coronary flow reserve and ischemia. Evidence indicates that the intima beneath the bridge is protected from atherosclerosis, and the proximal segment is more susceptible to the development of atherosclerotic lesions because of haemodynamic disturbances. Myocardial bridging is sometimes associated with overt pathology, as well as it can just be an incidental finding without any significance. Myocardial bridging may cause angina pectoris, myocardial infarction, life threatening arrhythmias and even sudden cardiac death but most of them are harmless. Furthermore depressed left ventricular function, myocardial stunning, early death after cardiac transplantation has been also reported. Although the exact management is not well known, beta blockers seem to be the first choice. Stenting is controversial and one must think “twice” before stenting the bridged coronary artery. We report a case of chance finding at multislice computed tomography coronary angiography of two myocardial bridging. Also this case focuses attention on myocardial bridging and it confirms that multislice computed tomography coronary angiography technology represents a useful, noninvasive imaging method of its assessment.     

ANT1 is reduced in sporadic inclusion body myositis

To investigate ANT1 and NF-κB expression in inclusion body myositis (IBM) muscle and to verify their possible roles in the pathogenesis of the disease, we collected muscle samples from five patients with IBM, polimyositis (PM) and controls. p65 form of NF-κB was analyzed using immunocytochemistry, Western blot and EMSA. Western blot of ANT1 was performed and confirmed by gene expression study. Mann–Whitney test was used for groups comparisons. NF-κB (p65) was found over-expressed both with western blot and EMSA, either in IBM or PM patients versus controls (p < 0.01). Expression of ANT1 were lower in IBM samples versus both PM and controls (p < 0.01). ANT1 reduction and NF-κB over-expression in IBM muscle could explain the lack of apoptosis in such disease. Normal ANT1 expression in PM could be related to the scarcity of mitochondrial abnormalities in the disease, but it could also suggest that these two conditions diverge in activating different anti-apoptotic pathways.     

Proteolytic processing of osteopontin by PHEX and accumulation of osteopontin fragments in Hyp mouse bone,the murine model of X‐linked hypophosphatemia

X‐linked hypophosphatemia (XLH/HYP)—with renal phosphate wasting, hypophosphatemia, osteomalacia, and tooth abscesses—is caused by mutations in the zinc‐metallopeptidase PHEX gene (phosphate‐regulating gene with homologies to endopeptidase on the X chromosome). PHEX is highly expressed by mineralized tissue cells. Inactivating mutations in PHEX lead to distal renal effects (implying accumulation of a secreted, circulating phosphaturic factor) and accumulation in bone and teeth of mineralization‐inhibiting, acidic serine‐ and aspartate‐rich motif (ASARM)‐containing peptides, which are proteolytically derived from the mineral‐binding matrix proteins of the SIBLING family (small, integrin‐binding ligand N‐linked glycoproteins). Although the latter observation suggests a local, direct matrix effect for PHEX, its physiologically relevant substrate protein(s) have not been identified. Here, we investigated two SIBLING proteins containing the ASARM motif—osteopontin (OPN) and bone sialoprotein (BSP)—as potential substrates for PHEX. Using cleavage assays, gel electrophoresis, and mass spectrometry, we report that OPN is a full‐length protein substrate for PHEX. Degradation of OPN was essentially complete, including hydrolysis of the ASARM motif, resulting in only very small residual fragments. Western blotting of Hyp (the murine homolog of human XLH) mouse bone extracts having no PHEX activity clearly showed accumulation of an ～35 kDa OPN fragment that was not present in wild‐type mouse bone. Immunohistochemistry and immunogold labeling (electron microscopy) for OPN in Hyp bone likewise showed an accumulation of OPN and/or its fragments compared with normal wild‐type bone. Incubation of Hyp mouse bone extracts with PHEX resulted in the complete degradation of these fragments. In conclusion, these results identify full‐length OPN and its fragments as novel, physiologically relevant substrates for PHEX, suggesting that accumulation of mineralization‐inhibiting OPN fragments may contribute to the mineralization defect seen in the osteomalacic bone characteristic of XLH/HYP. © 2013 American Society for Bone and Mineral Research.