Functional Assessment of TSC2 Variants Identified in Individuals with Tuberous Sclerosis Complex

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder caused by mutations in the TSC1 or TSC2 genes. The TSC1 and TSC2 gene products, TSC1 and TSC2, form a complex that inhibits the mammalian target of rapamycin (mTOR) complex 1 (TORC1). Here, we investigate the effects of 78 TSC2 variants identified in individuals suspected of TSC, on the function of the TSC1–TSC2 complex. According to our functional assessment, 40 variants disrupted the TSC1–TSC2‐dependent inhibition of TORC1. We classified 34 of these as pathogenic, three as probably pathogenic and three as possibly pathogenic. In one case, a likely effect on splicing as well as an effect on function was noted. In 15 cases, our functional assessment did not agree with the predictions of the SIFT amino acid substitution analysis software. Our data support the notion that different, nonterminating TSC2 mutations can have distinct effects on TSC1–TSC2 function, and therefore, on TSC pathology.     

Myocardial perfusion,oxidative metabolism,and free fatty acid uptake in patients with hypertrophic cardiomyopathy attributable to the Asp 175Asn mutation in the α-tropomyosin gene: A positron emission tomography study

Background  The relationship between myocardial metabolic changes and the severity of left ventricular (LV) hypertrophy in patients with hypertrophic cardiomyopathy (HCM) is largely unknown. We characterized metabolic abnormalities in patients with a genetically identical cause for HCM but with variable LV hypertrophy. Methods and Results  Eight patients with HCM attributable to the Asp175Asn mutation in the α-tropomyosin gene underwent myocardial perfusion, oxidative, and free fatty acid (FFA) metabolism measurements via positron emission tomography and oxygen 15-labeled water, carbon 11 acetate, and fluorine 14(R,S)-[18F] Fluoro-6-thia-heptadecanoic acid (18 FTHA). LV mass, work, and efficiency were assessed by echocardiography. Thirty-six healthy volunteers served as control subjects. Compared with control subjects, HCM patients had increased myocardial oxidative metabolism and FFA uptake (P<.05). However, in patients, LV mass was inversely related to global myocardial perfusion, oxidative metabolism, and FFA uptake (all P<.03), and regional wall thickness was inversely related to regional perfusion (P<.01), oxidative metabolism (P<.001), and FFA uptake (P<.01). Therefore patients with mild (LV mass less than median of 177 g) but not advanced LV hypertrophy were characterized by increased perfusion, oxidative metablism, and LV efficiency as compared with control subjects (P<.05). Conclusions  In HCM attributable to the Asp 175Asn mutation in the α-tropomyosin gene, myocardial oxidative metabolism and FFA metabolism are increased and inversely related to LV hypertrophy at both the whole heart and regional level. Increased metabolism and efficiency characterize patients with mild myocardial hypertrophy. These hypermetabolic alterations regress with advanced hypertrophy. Dis Tuunanen and Kuusisto contributed equally to this work This study was financially supported by an EVO grant (Kuopio University Hospital), as well as the Turunen Foundation, Instrumentarium Foundation, and Finish Cultural Foundation.     

Efficacy and safety outcomes in vitamin D supplement users in the fingolimod phase 3 trials

Background

Low serum levels of 25-hydroxyvitamin D have been associated with worse outcomes in multiple sclerosis (MS) patients treated with interferon-beta. Association of vitamin D nutrition on the outcomes of other MS therapies has been studied less.

Objective

Whether patients in the phase 3 fingolimod trials using vitamin D supplements have better clinical, MRI and safety outcomes than non-users.

Materials and methods

Pooled data from phase 3 FREEDOMS trials was analyzed post hoc. Vitamin D use was defined as ‘non-users’ (n = 562), ‘casual users’ (n = 157) and ‘daily users’ (usage 100% time in the study, n = 110).

Results

Expanded Disability Status Scale change from baseline to month 24, and annual relapse rate and proportion of patients with relapses were similar across the vitamin D user groups. Proportion of patients free of new/enlarging T2 lesions significantly favored vitamin D ‘daily users’ versus ‘non-users’. Mean number of lesions were lower and proportion of patients free of gadolinium-enhanced T1-lesions were higher in the ‘daily users’. At month 12, percent brain volume change was significantly lower in the ‘daily users’ versus ‘non-users’ and remained low at month 24 (non-significant). Incidence of depression was lower for vitamin D ‘daily users’ (non-significant).

Conclusions

We observed improved MRI outcomes on percent brain volume change and proportion of patients free of new/enlarging T2 lesions, and a trend of less depression in the ‘daily users’ of vitamin D supplement in patients in the FREEDOMS trials.

     

Toll-like receptor 7 (TLR7)-driven accumulation of a novel CD11c⁺ B-cell population is important for the development of autoimmunity

Females are more susceptible than males to many autoimmune diseases. The processes causing this phenomenon are incompletely understood. Here, we demonstrate that aged female mice acquire a previously uncharacterized population of B cells that we call age-associated B cells (ABCs) and that these cells express integrin α(X) chain (CD11c). This unexpected population also appears in young lupus-prone mice. On stimulation, CD11c(+) B cells, both from autoimmune-prone and healthy strains of mice, secrete autoantibodies, and depletion of these cells in vivo leads to reduction of autoreactive antibodies, suggesting that the cells might have a direct role in the development of autoimmunity. We have explored factors that contribute to appearance of ABCs and demonstrated that signaling through Toll-like receptor 7 is crucial for development of this B cell population. We were able to detect a similar population of B cells in the peripheral blood of some elderly women with autoimmune disease, suggesting that there may be parallels between the creation of ABC-like cells between mice and humans.     

Abdominal visceral findings in patients with Marfan syndrome.

PURPOSE: Marfan syndrome is an autosomal dominant disorder historically defined by well-characterized features in the cardiovascular, ocular, and skeletal systems. To date, there have been no reports concerning abdominal visceral findings in this disorder. The purpose of this study was to determine the prevalence of abdominal visceral findings in patients with Marfan syndrome. METHODS: Computed tomography or magnetic resonance studies of 69 patients with Marfan syndrome and an age- and sex-matched cohort of control subjects were reviewed. The presence of abdominal visceral findings was noted. Chi-square and Student t tests were used to determine significance of differences between the patient and control groups. This retrospective study was approved by the local institutional review board and determined to be exempt from Health Insurance Portability and Accountability Act reporting requirements. RESULTS: Renal cysts were present in 41 Marfan patients (59.4%) versus 21 control subjects (30.4%), P=0.001. The average number of renal cysts was greater in Marfan patients than controls (2.4 vs. 0.9, P=0.005). Hepatic cysts were present in 24 Marfan patients (34.8%) versus 12 control patients (17.3%), P=0.02. The average number of hepatic cysts was also greater in Marfan patients than controls (0.9 vs. 0.3, P=0.027). Cholelithiasis was present in 12 Marfan patients (18.1%) versus one control patient (1.5%), P<0.001. CONCLUSIONS: Marfan syndrome patients have liver and renal cysts more often, in increased number, and at an earlier age than controls, in addition to an increased prevalence of cholelithiasis. Further study will be needed to relate these findings to recent developments concerning the underlying molecular genetics of this disorder.     

A role of diffusion tensor imaging in movement disorder surgery

The safe and reversible nature of deep brain stimulation (DBS) has allowed movement disorder neurosurgery to become commonplace throughout the world. Fundamental understanding of individual patient’s anatomy is critical for optimizing the effects and side effects of DBS surgery. Three patients undergoing stereotactic surgery for movement disorders, at the institution’s intraoperative magnetic resonance imaging operating suite, were studied with fiber tractography. Stereotactic targets and fiber tractography were determined on preoperative magnetic resonance imagings using the Schaltenbrand–Wahren atlas for definition in the BrainLab iPlan software (BrainLAB Inc., Feldkirchen, Germany). Subthalamic nucleus, globus pallidus interna, and ventral intermediate nucleus targets were studied. Diffusion tensor imaging parameters used ranged from 2 to 8 mm for volume of interest in the x/y/z planes, fiber length was kept constant at 30 mm, and fractional anisotropy threshold varied from 0.20 to 0.45. Diffusion tensor imaging tractography allowed reliable and reproducible visualization and correlation between frontal eye field, premotor, primary motor, and primary sensory cortices via corticospinal tracts and corticopontocerebellar tracts. There is an apparent increase in the number of cortical regions targeted by the fiber tracts as the region of interest is enlarged. This represents a possible mechanism of the increased effects and side effects observed with higher stimulation voltages. Currently available diffusion tensor imaging techniques allow potential methods to characterize the effects and side effects of DBS. This technology has the potential of being a powerful tool to optimize DBS neurosurgery.     

Anti-Epstein-Barr virus (EBV) activity of beta-L-5-iododioxolane uracil is dependent on EBV thymidine kinase

beta-L-5-Iododioxolane uracil was shown to have potent anti-Epstein-Barr virus (EBV) activity (50% effective concentration = 0.03 microM) with low cytotoxicity (50% cytotoxic concentration = 1,000 microM). It exerts its antiviral activity by suppressing replicative EBV DNA and viral protein synthesis. This compound is phosphorylated in cells where the EBV is replicating but not in cells where the EBV is latent. EBV-specific thymidine kinase could phosphorylate beta-L-5-iododioxolane uracil to the monophosphate metabolite. The K(m) of beta-L-5-iododioxolane uracil with EBV thymidine kinase was estimated to be 5.5 microM, which is similar to that obtained with thymidine but about fivefold higher than that obtained with 2' fluoro-5-methyl-beta-L-arabinofuranosyl uracil, the first L-nucleoside analogue discovered to have anti-EBV activity. The relative V(max) is seven times higher than that of thymidine. The anti-EBV activity of beta-L-5-iododioxolane uracil and its intracellular phosphorylation could be inhibited by 5'-ethynylthymidine, a potent EBV thymidine kinase inhibitor. The present study suggests that beta-L-5-iododioxolane uracil exerts its action after phosphorylation; therefore, EBV thymidine kinase is critical for the antiviral action of this drug.     

Effects of short-term exposure to 0.2 ppm ozone on biomarkers of inflammation in sputum, exhaled nitric oxide, and lung function in subjects with mild atopic asthma

To gain further insight into the kinetics of airway inflammatory response and explore the possibility of nitric oxide as a surrogate marker of the lower airway inflammatory response to ozone, nine subjects with mild atopic asthma were exposed to filtered air or 0.2 ppm ozone for 2 hours with intermittent exercise. Lung function was measured at baseline and immediately after exposures. Sputum induction was performed at 6 hours and at 24 hours after exposures, and exhaled nitric oxide levels were measured at baseline, immediately, 6, and 24 hours after both exposures. A significant decline in forced expiratory volume in one second and inspiratory capacity was detectable following exposure to ozone. In addition, a 2-fold increase was observed in the percentage of polymorphonuclear leukocytes 6 hours after exposure to ozone, with no changes in other biomarkers at this time point. By 24 hours after ozone exposure, the neutrophilia had subsided but there was an increase in albumin, total protein, myeloperoxidase, and eosinophil cationic protein. Exhaled nitric oxide levels, histamine, interleukin-8, and growth-related oncogene-alpha in sputum did not change significantly following ozone exposure. It was concluded that short-term ozone exposure induces an acute inflammatory response in asthmatic airways, characterized by early polymorphonuclear leukocyte influx followed by plasma extravasation and activation of eosinophils and neutrophils. Exhaled nitric oxide is not a useful marker for detecting inflammatory response to ozone in persons with mild asthma.     

A case of ring 14 chromosome with ocular manifestations

BACKGROUND: Ring 14 chromosome has been reported to be associated with mental retardation, craniofacial dysmorphology, and epilepsy. Flecked and/or pigmented retina are also ocular manifestations of this disease. CASE: A 29-year-old female suffered from seizures and developmental and growth delay. Narrow palpebral fissura, broad flat nose, large auricula, high arched palate, and short neck were present. Chromosomal analysis disclosed her ring 14 chromosome (p 11.2 q 32.3). Ophthalmologically, cortical cataract, refractive error (right--3.00 D, left--1.50 D), and yellow-white flecks in the macula and yellow-white spots in the mid-peripheral retina in both eyes were present. CONCLUSIONS: To date, ophthalmic changes concomitant to a breakpoint at 14 q 32.2 have been reported. We report a case of ring 14 chromosome with breakpoint at 14 q 32.3 which showed yellow flecks in the macula and mid-peripheral retina.