Laforin preferentially binds the neurotoxic starch-like polyglucosans, which form in its absence in progressive myoclonus epilepsy

Lafora disease (LD) is a fatal and the most common form of adolescent-onset progressive epilepsy. Fulminant endoplasmic reticulum (ER)-associated depositions of starch-like long-stranded, poorly branched glycogen molecules [known as polyglucosans, which accumulate to form Lafora bodies (LBs)] are seen in neuronal perikarya and dendrites, liver, skeletal muscle and heart. The disease is caused by loss of function of the laforin dual-specificity phosphatase or the malin E3 ubiquitin ligase. Towards understanding the pathogenesis of polyglucosans in LD, we generated a transgenic mouse overexpressing inactivated laforin to trap normal laforin's unknown substrate. The trap was successful and LBs formed in liver, muscle, neuronal perikarya and dendrites. Using immunogold electron microscopy, we show that laforin is found in close proximity to the ER surrounding the polyglucosan accumulations. In neurons, it compartmentalizes to perikaryon and dendrites and not to axons. Importantly, it binds polyglucosans, establishing for the first time a direct association between the disease-defining storage product and disease protein. It preferentially binds polyglucosans over glycogen in vivo and starch over glycogen in vitro, suggesting that laforin's role begins after the appearance of polyglucosans and that the laforin pathway is involved in monitoring for and then preventing the formation of polyglucosans. In addition, we show that the laforin interacting protein, EPM2AIP1, also localizes on the polyglucosan masses, and we confirm laforin's intense binding to LBs in human LD biopsy material.     

Quantifying myocardial perfusion using contrast echocardiography

There is a complex relation between what can be seen using perfusion imaging techniques, and what can be measured.     

Effect of treatment interruption monitored by CD4 cell count on mitochondrial DNA content in HIV-infected patients: a prospective study

BACKGROUND: HIV infection per se and HAART can alter mitochondrial functionality, leading to a decrease in mitochondrial DNA content. OBJECTIVE: To evaluate whether treatment interruption monitored by CD4 cell count can restore mitochondrial DNA content in peripheral blood lymphocytes. METHODS: Mitochondrial DNA content was measured in platelet-free CD4 and CD8 T cells by real-time polymerase chain reaction; flow cytometry was used to identify and quantify activated CD4 and CD8 T lymphocytes. RESULTS: The 30 patients had been treated for a mean of 107 months (range, 27-197). Median CD4 cell count at discontinuation was 702 cells/microl (range, 547-798). Median observational time from HAART discontinuation was 11.3 months (range, 4-26). Discontinuation of treatment provoked significant increases in mitochondrial DNA in CD8 T cells, which started only 6 months after therapy discontinuation [5.12 copies/cell per month from 0 to 6 months (P = 0.37) and 26.96 copies/cell per month from 6 to 12 months (P < 0.0001)]. CONCLUSIONS: This study is the first showing that mitochondrial DNA content can increase in peripheral blood lymphocytes during treatment interruption, but only after at least 6 months of interruption. Consequently, interruptions of shorter periods, whether by clinician or patient decision, are unlikely to allow restoration of mitochondrial DNA and so decrease HAART-related toxicity.     

Sequential swallows have no influence on esophageal contractions of patients with iron deficiency anemia

BACKGROUND: An experimental study showed that thyropharyngeal, cricopharyngeal and cervical esophageal muscles of rabbits with iron deficiency anemia had morphological changes similar to those observed in muscular dystrophy, causing myastenic changes in muscles involved in swallowing. Our hypothesis is that patients with iron deficiency anemia may have a decrease in esophageal contractions with successive swallows. PATIENTS AND METHOD: We studied the esophageal motility of 12 women with iron deficiency anemia aged 31 to 50 years (median 36 years) with serum iron from 11 to 40 mug/dL (median 21 mug/dL), and 13 asymptomatic women aged 26 to 49 years (median 35 years) with serum iron over 60 mug/dL. We used the manometric method with continuous perfusion. The esophageal contractions were measured at 3, 9 and 15 cm from the upper margin of a sleeve that straddled the lower esophageal sphincter. Each subject performed 10 swallows of a 2 mL bolus of water alternated with 10 swallows of a 7 mL bolus, with an interval of 30 seconds between swallows. We measured the amplitude, duration, velocity and area under the curve of contractions. RESULTS: There was no difference between the swallows of a 2 mL or 7 mL bolus. The amplitude, duration and area under the curve were lower in patients with iron deficiency than in asymptomatic volunteers, mainly in the proximal and middle esophageal body. There was no difference in velocity. Sequential swallows did not change contraction amplitude, duration, velocity or area under curve in patients and volunteers. CONCLUSION: Although the power of esophageal contractions was decreased in patients with iron deficiency anemia, sequential swallows did not cause further impairment.     

Assessment of coronary stenoses of graded severity by myocardial contrast echocardiography.

BACKGROUND: Myocardial contrast echocardiography (MCE) has potential value in the assessment and quantitation of myocardial perfusion defects. However, the severity of stenosis detectable by MCE and its diagnostic accuracy remain undefined. Thus, we produced coronary stenoses of variable severity and quantified their effect on MCE. METHODS AND RESULTS: Three grades of left anterior descending (LAD) obstructions were produced in 7 open-chest swine. The stenoses were nonflow-limiting at rest, but decreased coronary hyperemia by 31.3% +/- 4.7%, 69.9% +/- 5.3% and 98.9% +/- 1.1%, respectively. Regional myocardial blood flow (RBF) was measured with fluorescent microspheres and was expressed as the ratio of LAD and control (LCx) beds. MCE was performed with 0.3 mg/kg intravenous AF0150 during ECG-gated harmonic imaging in short-axis view. Background-subtracted peak intensity (PI) was expressed as the ratio of LAD/LCx beds. Both RBF and PI ratios progressively decreased with increasing grades of stenosis. MCE showed a significant correlation with RBF (r = 0.74; P <.0001). Ratios of both PI and RBF differed significantly from baseline when coronary hyperemia was reduced more than 50%. An LAD/LCx ratio less than 0.6 by MCE yielded 61% and 83% sensitivity and 85% and 76% specificity with stenosis that reduced coronary hyperemia more than 50% and more than 75%, respectively. CONCLUSION: MCE with intravenous AF0150 during vasodilation correctly depicted the progressive reduction of flow ratios produced by graded coronary stenoses. A significant reduction of PI ratio was observed with stenosis causing more than 50% reduction of coronary hyperemia. An MCE ratio in stenosed/control beds could be selected, which exhibited good sensitivity and specificity in the identification of coronary stenosis.     

Evaluation of long-term efficacy and tolerability of irbesartan in elderly hypertensive patients with renal impairment in an open-label study

Background: Hypertension, left untreated, can lead to serious complications, including stroke myocardial infarction, and renal failure. Because lowering blood pressure correlates with slowing of renal disease progression, the control of hypertension in the presence of renal disease is essential.Objective: We evaluated the efficacy, tolerability, and safety of irbesartan alone or in combination with other antihypertensive agents in elderly patients with hypertension and chronic renal insufficiency.Methods: Patients > 65 years of age with hypertension (sitting diastolic blood pressure [SiDBP] 90-115 mm Hg) and chronic renal sufficiency that was mild (creatinine clearance [CrCL] 30-60 mL/min per 1.73 m²) or moderate to severe CrCL 10-29 mL/min per 1.73 m²) were enrolled. After a 3-week placebo run-in period, irbesartan was administered for 12 months at 150 mg/d. After 4 weeks of therapy, patients whose blood pressure was not adequately controlled (ie, SiDBP ≥90 mm Hg or <5 mm Hg decrease from baseline) had an additional antihypertensive agent added to their daily irbesartan regimen; dosage adjustment of the second drug was permitted after 2 weeks to optimize blood pressure control. Twenty-four-hour CrCL was determined, and renal clearance studies of inulin and p-aminohippurate were performed in a subset of patients.Results: A total of 32 patients (21 men, 11 women; mean age, 70.4 years) were enrolled. Thirty patients had mild renal insufficiency (mean CrCL, 44.45 mL/min per 1.73 m²) and 2 patients had moderate to severe renal insufficiency (mean CrCL 21.32 mL/min per 1.73 m²). Trough sitting blood pressures were reduced at the end of the first week of treatment in all groups. After 8 weeks, 12 weeks, and 1 year of treatment, the mean reductions in systolic blood pressure (SBP)/DBP were −11.9/−8.7 mm Hg, −10.8/−9.4 mm Hg, and −14.7/−12.1 mm Hg, respectively, in patients with mild renal insufficiency and −7.7/−6.3 mm Hg, −13.1/−11.8 mm Hg, and −14.1/−10.6 mm Hg in patients with moderate to severe renal insufficiency. CrCL, glomerular filtration rate, and effective renal plasma flow, as measured in a subset of 11 patients, were stable. Treatment was discontinued for 3 patients because of a clinical adverse event or laboratory parameter abnormality. Hyperkalemia (>6 mEq/L) requiring discontinuation of irbesartan occurred in 1 patient with moderate to severe renal insufficiency.Conclusion: The results of this study suggest that irbesartan, as monotherapy (150 mg once daily) or in combination with other antihypertensive drugs, is effective in reducing blood pressure in elderly hypertensive patients with chronic renal impairment and that irbesartan regimens are well tolerated in this population.     

Noninvasive evaluation of flow reserve in the left anterior descending coronary artery in patients with cardiac syndrome X

Data on coronary flow reserve (CFR) in patients with syndrome X are still controversial. Further, noninvasive evaluation of epicardial and microvascular flow reserves in these patients has never been performed. In 17 patients with syndrome X and in 17 age- and gender-matched control subjects, CFR in the mid left anterior descending coronary artery (LAD) was evaluated by transthoracic color and pulse-wave Doppler using a 7-mHz probe (Sequoia, Siemens). Peak diastolic LAD flow was calculated at rest and at peak adenosine (140 microg/kg/min intravenously in 90 seconds). Myocardial contrast echocardiography (MCE) was performed at rest and during adenosine use by real-time cadence pulse sequencing and intravenous SonoVue (Bracco; 5 ml at 1 ml/min) and microvascular blood volume (A), velocity (beta), and flow (Axbeta) by replenishing curves (y = A[1 - e(betat)]). CFR was measured by Doppler echocardiography as an adenosine/rest velocity ratio and by MCE as a microvascular volume, velocity, and flow adenosine/rest ratio. Compared with controls, patients with syndrome X demonstrated lower LAD CFR and velocity and flow microvascular flow reserves (p <0.01, <0.005, and <0.005, respectively). In patients with syndrome X, those with angina and ST-segment depression during adenosine testing had even lower LAD CFR and velocity and flow microvascular flow reserves compared with those with no symptoms (p <0.0001, <0.0001, and <0.005, respectively). LAD CFR demonstrated a significant linear correlation with velocity microvascular flow reserve (r = 0.92, p <0.0001) and flow microvascular flow reserve (r = 0.77, p <0.0001). In conclusion, CFR in the LAD, successfully evaluated by transthoracic Doppler echocardiography and MCE, is significantly decreased in patients with syndrome X and even more in those with angina pectoris and ST-segment depression during adenosine testing. Thus, noninvasive evaluation of CFR by echocardiography is feasible and provides information on the severity of microvascular impairment.     

Comparison of diagnostic accuracy between three different rules of interpreting high sensitivity troponin T results

With the introduction of high sensitivity troponin-T (hs-TnT) assay, clinicians face more patients with 'positive' results but without myocardial infarction. Repeated hs-TnT determinations are warranted to improve specificity. The aim of this study was to compare diagnostic accuracy of three different interpretation rules for two hs-TnT results taken 6 h apart. After adjusting for clinical differences, hs-TnT results were recoded according to the three rules. Rule1: hs-TnT >13 ng/L in at least one determination. Rule2: change of >20 % between the two measures. Rule3: change >50 % if baseline hs-TnT 14-53 ng/L and >20 % if baseline >54 ng/L. The sensitivity, specificity and ROC curves were compared. The sensitivity analysis was used to generate post-test probability for any test result. Primary outcome was the evidence of coronary critical stenosis (CCS) on coronary angiography in patients with high-risk chest pain. 183 patients were analyzed (38.3 %) among all patients presenting with chest pain during the study period. CCS was found in 80 (43.7 %) cases. The specificity was 0.62 (0.52-0.71), 0.76 (0.66-0.84) and 0.83 (0.74-0.89) for rules 1, 2 and 3, respectively (P < 0.01). Sensitivity decreased with increasing specificity (P < 0.01). Overall diagnostic accuracy did not differ among the three rules (AUC curves difference P = 0.12). Sensitivity analysis showed a 25 % relative gain in predicting CCS using rule 3 compared to rule 1. Changes between two determinations of hs-TnT 6 h apart effectively improved specificity for CCS presence in high-risk chest pain patients. There was a parallel loss in sensitivity that discouraged any use of such changes as a unique way to interpret the new hs-TnT results.