Increased lipolysis and altered lipid homeostasis protect γ-synuclein–null mutant mice from diet-induced obesity

Synucleins are a family of homologous proteins principally known for their involvement in neurodegeneration. γ-Synuclein is highly expressed in human white adipose tissue and increased in obesity. Here we show that γ-synuclein is nutritionally regulated in white adipose tissue whereas its loss partially protects mice from high-fat diet (HFD)–induced obesity and ameliorates some of the associated metabolic complications. Compared with HFD-fed WT mice, HFD-fed γ-synuclein–null mutant mice display increased lipolysis, lipid oxidation, and energy expenditure, and reduced adipocyte hypertrophy. Knockdown of γ-synuclein in adipocytes causes redistribution of the key lipolytic enzyme ATGL to lipid droplets and increases lipolysis. γ-Synuclein–deficient adipocytes also contain fewer SNARE complexes of a type involved in lipid droplet fusion. We hypothesize that γ-synuclein may deliver SNAP-23 to the SNARE complexes under lipogenic conditions. Via these independent but complementary roles, γ-synuclein may coordinately modulate lipid storage by influencing lipolysis and lipid droplet formation. Our data reveal γ-synuclein as a regulator of lipid handling in adipocytes, the function of which is particularly important in conditions of nutrient excess.Understanding the link between increased adiposity and the development of metabolic disease may reveal novel therapeutic targets to counter the rising pandemic of obesity. Inhibiting adipose tissue expansion alone is likely to worsen metabolic outcome, as evidenced by human syndromes of lipodystrophy, whereby inappropriately decreased adipose mass causes severe metabolic disorders (1). Indeed, adipose tissue dysfunction and/or exceeded adipose storage capacity may underlie ectopic lipid accumulation and lipotoxicity in obesity (2). Therefore, a major challenge is to identify pathways via which adiposity can be reduced without concomitant increases in circulating lipids and attendant metabolic disease. Achieving this goal requires a better understanding of the molecular mechanisms that regulate lipid metabolism and storage in adipocytes, particularly in times of energy surplus.γ-Synuclein belongs to the synuclein family of proteins, whose founder member α-synuclein is best known for its links with neurodegenerative diseases, most notably Parkinson disease (3). To date, no clear cellular role is attributed to γ-synuclein, and ablation of γ-synuclein causes only minor changes in the nervous system (4–7). Recently, we and others have reported high levels of γ-synuclein expression in adipose tissue of humans and other mammals (8, 9). Moreover, expression of γ-synuclein is increased in the adipose tissue of obese humans and decreased during caloric restriction (8).Here we demonstrate that γ-synuclein–null mice display significantly reduced adiposity and fewer metabolic derangements compared with WT mice following high-fat feeding. This appears to result from increased adipocyte lipolysis coupled to enhanced whole-body lipid oxidation and energy expenditure. At a molecular level, we identify dual roles for γ-synuclein independently regulating lipid droplet fusion and adipocyte lipolysis to coordinately regulate triglyceride (TG) storage in adipocytes. Together, our observations reveal that γ-synuclein is a regulator of lipid metabolism and, hence, a potential therapeutic target for treatment of obesity and associated metabolic diseases.     

Functional capacity of Brazilian patients with Parkinson's disease (PD): relationship between clinical characteristics and disease severity

The present study had three objectives: (a) to characterize the functional capacity of patients with PD, (b) to assess the relationship between the physical fitness components of functional capacity with clinical characteristics and disease severity, and (c) to compare the physical fitness components of functional capacity with clinical characteristics according to disease severity. The study included 54 patients with idiopathic PD who were distributed into two groups according to PD severity: unilateral group (n=35); and bilateral group (n=19). All patients underwent psychiatric assessment by means of the Hoehn and Yahr (HY) staging of PD, the Unified Parkinson's Disease Rating Scale (UPDRS), the Hospital Anxiety and Depression Scale (HADS-A and HADS-D, respectively), and The Mini-Mental State Examination (MMSE). The physical fitness components of functional capacity were evaluated over a 2-day period, using recommendations by the American Alliance for Health, Physical Education, Recreation and Dance, and the Berg Balance Scale (BBS). Pearson correlation coefficients and multiple regressions were calculated to test the correlation between functional capacity and clinical characteristics, and to predict clinical scores from physical performance, respectively. Clinical variables and physical component data were compared between groups using analysis of variance to determine the effects of disease severity. Patients with advanced disease showed low levels of functional capacity. Interestingly, patients with good functional capacity in one of the physical fitness components also showed good capacities in the other components. Disease severity is a major factor affecting functional capacity and clinical characteristics. Medical providers should take disease severity into consideration when prescribing physical activity for PD patients, since the relationship between functional capacity and clinical characteristics is dependent on disease severity.     

Enamel defects associated with coeliac disease: putative role of antibodies against gliadin in pathogenesis

Enamel defects in the permanent teeth of patients with coeliac disease (CD) are often reported as an atypical manifestation, sometimes being suggestive of an undiagnosed atypical disease. We proposed to explore the pathogenesis of these oral defects, which are poorly studied. Sequence analyses of proteins from gluten (gliadins) and of proline-rich enamel proteins (amelogenin and ameloblastin) suggested the presence of common antigenic motifs. Therefore, we analyzed, by ELISA and western blotting, the reactivity of sera from patients with CD against gliadin and enamel-derived peptides. Correlation analyses between the levels of specific antibodies against gliadin and enamel derived peptides and inhibition experiments confirmed the presence of cross-reactive antibodies. Immunoblot analysis revealed that the most prominent component in enamel matrix derivative (of approximately 18.6 kDa), identified by an amelogenin-specific antibody, is recognized by sera from patients with CD; in addition, several fractions of pure gliadin were recognized by amelogenin-specific antibody. In agreement, sera from mice immunized with enamel matrix-derived proteins generated antibodies that recognized a peptide (of approximately 21.2 kDa) derived from gliadin. In conclusion, antibodies against gliadin generated in patients with CD can react in vitro with a major enamel protein. The involvement of anti-gliadin serum in the pathogenesis of enamel defects in children with untreated CD can be hypothesized on the basis of these novel results.     

Melatonin membrane receptors in peripheral tissues: distribution and functions

Many of melatonin's actions are mediated through interaction with the G-protein coupled membrane bound melatonin receptors type 1 and type 2 (MT1 and MT2, respectively) or, indirectly with nuclear orphan receptors from the RORα/RZR family. Melatonin also binds to the quinone reductase II enzyme, previously defined the MT3 receptor. Melatonin receptors are widely distributed in the body; herein we summarize their expression and actions in non-neural tissues. Several controversies still exist regarding, for example, whether melatonin binds the RORα/RZR family. Studies of the peripheral distribution of melatonin receptors are important since they are attractive targets for immunomodulation, regulation of endocrine, reproductive and cardiovascular functions, modulation of skin pigmentation, hair growth, cancerogenesis, and aging. Melatonin receptor agonists and antagonists have an exciting future since they could define multiple mechanisms by which melatonin modulates the complexity of such a wide variety of physiological and pathological processes.     

A single pentylenetetrazole-induced clonic-tonic seizure episode is accompanied by a slowly developing cognitive decline in rats

According to different studies, between 5% and 10% of people suffer a single isolated seizure episode at some time in their life. However, little is known about the effects of a single seizure episode on cognitive function, and clinical investigations of this issue are not easy to perform. In this situation, animal models may be a reasonable choice. The aim of our study was to follow the time course of delayed effects of generalized clonic-tonic convulsions on learning and memory functions in rats. A clonic-tonic seizure episode was induced by a single i.p. injection of pentylenetetrazole (70 mg/kg). Different behavioral tests were performed between days 10 and 100 after the convulsant administration. A single seizure episode resulted in a gradual decline in short-term memory function as assessed by novel object recognition and social recognition tests. The seizure episode induced a quick increase in hippocampal cell proliferation; however, the excessive newly generated cells seemed to be eliminated by the time of obvious cognitive impairment. These observations are indicative of a slowly developing and long-lasting influence of a single seizure episode on cognitive function. A rather long time period between the seizure episode and the manifestations of cognitive decline provides a window for a possible therapeutic intervention, and an elaboration of such “post-conditioning” treatments may be a promising opportunity to prevent subsequent mental impairments in patients.     

Challenges and strategies in recruiting, interviewing, and retaining recent Latino immigrants in substance abuse and HIV epidemiologic studies

The growth of immigrant populations in the United States over the past 20 years has increased the need to enhance understanding about the risk factors that influence their substance abuse and HIV risk behaviors. Today, Latinos account for the largest majority of immigrants gaining entry into the United States. As the largest and fastest growing minority subgroup in the United States, they bear a disproportionate burden of disease and death compared to non-Latinos. Latinos are confronted with escalating HIV and substance-abuse problems, particularly Latinos between the ages of 18-34. This paper is based on our longitudinal study on the drug using and HIV risk behaviors of 527 recent Latino immigrants between the ages of 18-34 who have lived in the United States less than 1 year. The data collection activities of this study have provided insights in identifying, recruiting, interviewing, and retaining Latinos in community-based studies. Strategies, such as utilizing a combination of translation techniques, ensured the development and implementation of culturally appropriate questionnaires. Respondent-driven sampling facilitated identifying participants. Establishing rapport and trust was critical for interviewing, and maintaining a tracking protocol was most important for retention. The lessons learned from this study can guide substance abuse and HIV researchers when recruiting, interviewing, and retaining recent Latino immigrants in future epidemiologic studies.     

Post-ablation prolongation of atrioventricular nodal refractory period is correlated with long-term success of cryoablation for atrioventricular nodal reentrant tachycardia in the case of the persistence of a residual jump

Purpose

A residual slow pathway after successful cryoablation for atrioventricular nodal reentrant tachycardia (AVNRT) is correlated with a higher recurrence rate. We described determinants of recurrence in subjects with a residual jump.

Methods

We analyzed the data of subjects with acute successful slow pathway cryoablation for AVNRT using a 6-mm-tip cryocatheter. Success was defined as AVNRT non-inducibility. Patients with no baseline elicitable jump, no inducible AVNRT, and transient first atrioventricular (AV) block at the last site were excluded.

Results

From 371 patients who underwent cryoablation from May 2002 to March 2011, 303 fulfilled the entry criteria (mean age, 41?±?16; 222 women). Baseline AV nodal effective refractory period (ERP) was 272?±?57?ms, postprocedural 331?±?64 (P?P?=?0.01). In patients with a jump, only ?? AV nodal ERP was correlated with recurrence (37?±?41 vs. 68?±?47?ms; P?30?ms (P?Conclusions Suppression of slow pathway conduction is the optimal endpoint for AVNRT cryoablation. A residual jump can be tolerated if AV nodal ERP postcryoablation is prolonged >30?ms.