Studies of multifunctional DNA polymerase I from the extremely radiation resistant Deinococcus radiodurans: Recombinant expression, purification and characterization of the full-length protein and its large fragment

Deinococcus radiodurans is a bacterium with extreme resistance to desiccation and radiation. Although the origins of this extreme resistance have not been fully elucidated, an efficient DNA repair machinery that includes the enzyme DNA polymerase I, is potentially crucial as part of a protection mechanism. Here we have cloned and performed small, medium, and large-scale expression of full-length D. radiodurans DNA polymerase I (DrPolI) as well as the large/Klenow fragment (DrKlenow). We then carried out functional characterization of 5' exonuclease, DNA strand displacement and polymerase activities of these proteins using gel-based and molecular beacon-based biochemical assays. With the same expression and purification strategy, we got higher yield in the production of DrKlenow than of the full-length protein, approximately 2.5 mg per liter of culture. Moreover, we detected a prominent 5' exonuclease activity of DrPolI in vitro. This activity and, DrKlenow strand displacement and DNA polymerase activities are preferentially stimulated at pH 8.0-8.5 and are reduced by addition of NaCl. Interestingly, both protein variants are more thermostable at pH 6.0-6.5. The characterization of DrPolI's multiple functions provides new insights into the enzyme's role in DNA repair pathways, and how the modulation of these functions is potentially used by D. radiodurans as a survival strategy.

Online gaming dependency, attention levels and sleep quality among online gamers

Introduction

The persistent and recurrent use of the internet to engage in games, often with other players, which leads to clinically considerable deficits and online dependency still lacks more research support its impact of attentional levels and Sleep Quality.

Objectives

To assess levels of Online Gaming Dependency, its impact on attention levels and quality of sleep among online gamers.

Methods

The following instruments were used: a sociodemographic questionnaire, as well as the Video Game Behavior Assessment Scale (α = .842) and the Portuguese version of Color and Words Stroop Test. The sample consists of 66 individuals, 92.3% male and 7.7% female, with an average age of 23.1 (SD ± 4.07).

Results

Mild levels of online gaming dependency were obtained. Male gamers presented higher motivation to play online games, and higher levels of Stroop interference. Regarding the association between gaming behaviors and quality of sleep, results show that individuals who have difficulty falling asleep show greater motivation to play online games, a greater degree of concern with daily life and a greater frequency of negative behaviors in relation to online gambling.

Conclusions

The results show the importance of an increase in investigations in this area, as well as to the development of psychological assessment instruments and psychological intervention strategies, based on scientific evidence, on the different variables under study, in order to improve the quality of life in of individuals.

Cytomegalovirus optic neuropathy in a young immunocompetent patient

Cytomegalovirus (CMV) infection is common worldwide, but is usually a subclinical or self-limited infection in immunocompetent patients. On the contrary, most of the ocular and central nervous system involvement occurs in immunosuppressed patient, and usually has severe consequences. Ocular manifestations of CMV infection are frequent in immunosuppressed patients (notably keratouveitis, retinitis and retinal branch angiitis), but a few cases of optic neuropathy (mostly papillitis) have been reported in the literature in immunocompetent patients. We report a case of a young and previously healthy female patient who developed a CMV optic neuropathy after a presumed CMV reinfection. Viral copies were detected in both blood and cerebrospinal fluid, as well as a high IgG titre and no evidence of immunosuppression was found. Clinical improvement was seen after high-dose corticosteroids and ganciclovir.

Metabolically healthy obesity in a young population assisted by the Family Health Strategy in Brazil

Background

Obesity is increasing in younger populations, and is associated with a high cardiovascular (CV) risk, however, it is not clear whether metabolically healthy obesity (MHO) may have a lower CV risk or if it is just an earlier stage of the disease.

Objective

To evaluate the prevalence and CV risk factors associated with MHO in a young population assisted by a Family Health Care unit in a large urban center in Brazil.

Methods

A cross-sectional population study for CV risk assessment in adults aged 20-50 years old from a FHC unit in Rio de Janeiro. Demographic, anthropometric data and CV risk factors were recorded. All underwent office blood pressure (OBP) measurements, laboratory evaluation (lipid and glycidic profile). Obesity was defined as a BMI ≥ 30 kg/m2 and MHO are those who have less than 3 of the following criteria: hypertension, diabetes, total cholesterol ≥ 200 mg/dL, HDL<40 mg/dL (men) and 50 mg/dL (women), triglycerides>150 mg/dL and increased waist circumference.

Results

A total of 632 individuals were evaluated (60% female; mean age 37 ± 9 years). The prevalence of obesity was 26%, of which 73% were classified as MHO. Obeses are older, with a higher prevalence of physical inactivity (51% vs 41%, p = 0.03), hypertension (44% vs 19%, p < 0.001), dyslipidemia (50% vs 36%, p = 0.002) and diabetes (7% vs 2%, p = 0.001) with higher systolic OBP. MHO compared to unhealthy ones are significantly younger and smoke less. Despite being obese, they have lower BMI (33.6 vs 35.2 kg/m2, p = 0.02) and abdominal circumference (102 vs 110 cm, p = 0.03), with lower diastolic BP.

Conclusions

MHO was more prevalent in this young population and seems to have a lower CV risk, however it is not clear whether these younger and less obese individuals are only at an earlier stage of the disease. Perhaps the CV diseases onset is postponed for a few years. Even so, these individuals should not be excluded from public health policies as a form of primary prevention.

Key messages

In this young population, MHO was more prevalent and presented a lower CV risk. The follow-up of MHO will show if they are really healthy or if they are at an early stage of the disease.

Cardiovascular risk factors and social determinants in a population study in Rio de Janeiro, Brazil

Background

The association of cardiovascular (CV) diseases and their risk factors with socioeconomic status has been well described, but its influence is often underestimated in epidemiological studies in Brazil.

Objective

To evaluate the relationship between the main CV risk factors and socioeconomic indicators in a population of adults registered in a Family Health Care (FHC) unit in a great urban center - Rio de Janeiro, Brazil.

Methods

Cross-sectional population study that included adults aged between 20 and 50 years living in the area covered by the FHC unit in Rio de Janeiro. Demographic data (gender and age), socioeconomic data (education level, profession, employment), CV risk factors (smoking, sedentary lifestyle, obesity, hypertension, diabetes, dyslipidemia) were recorded. The metabolic profile is evaluated through laboratory tests. Those who studied up to high school were considered poorly educated.

Results

604 individuals were enrolled [39% male, mean age: 38.8 ± 8,9 years] The median of schooling was 12 years. 288 individuals had high schooling, 44.5% were male. A total of 130 individuals did not study or work. Women with low education had a higher risk of smoking, obesity and hypertension with no difference regarding labor or study activities. Otherwise, men with low education had a higher risk of sedentary lifestyle and hypertension. Among men, not working or studying increased the risk of smoking and hypertension.

Conclusions

We found an inverse association between socioeconomic conditions and the prevalence of CV risk factors. Women are more affected by low schooling, while men are more affected by their working occupation. The study suggests that socioeconomic factors influence the CV risk, affecting men and women differently, pointing to the need for more comprehensive public health policies that effectively reverse this situation.

Key messages

We found an inverse association between socioeconomic conditions and the prevalence of CV risk factors. Socioeconomic factors influence cardiovascular risk differently according to gender.

C-reactive protein as a predictor of mild cognitive impairment conversion into Alzheimer's disease dementia

BACKGROUND AND AIMS

Increasing evidence suggests that inflammation plays an important role in brain aging and neurodegeneration. Pathological studies demonstrate the presence of C-reactive protein (CRP) in the senile plaques and neurofibrillary tangles in Alzheimer's disease (AD) brain tissue suggesting that CRP may play a role in its neuropathological processes. Some findings suggest that midlife elevations of serum CRP are a risk factor for AD. However, others found lower CRP levels in mild or moderate AD than in controls, suggesting that CRP levels could be different in different stages of disease. We aimed to assess the role of CRP as a predictor of Mild cognitive impairment (MCI) conversion into AD dementia.

METHODS

We retrospectively reviewed the cohort of MCI patients followed at the Dementia Clinic, Neurology Department of University Hospital of Coimbra. We collected demographical, neuropsychological, genetic and laboratorial variables (including serum CRP measurements at the time of baseline laboratory tests). A Cox regression model was performed adjusted for the collected variables preconsidered to be predictors of dementia and the variable being studied (CRP) to assess for independent predictors of conversion.

RESULTS

We included 130 patients, 58.5% female, with a mean age of onset of 65.5 ± 9.1 years and age at first assessment of 69.3 ± 8.5 years. The mean CRP was 0.33 ± 0.58 mg/dl. At follow-up (mean, 36.9 ± 27.0 months) 42.3% of MCI patients converted to dementia. Lower CSF Aβ42 (HR = 0.999, 95%CI = [0.997, 1.000], p = 0.015), lower MMSE score (HR = 0.864, 95%CI = [0.510, 1.595], p = 0.008) and lower CRP quartile (HR = 0.597, 95%CI = [0.435, 0.819], p = 0.001) were independent predictors of conversion.

CONCLUSION

CRP may add information of risk of conversion in MCI patients. Patients with lower CRP levels appear to have a more rapid conversion to AD dementia.

P3563The influence of circadian patterand obstructive sleep apnean of blood pressure in nocturnal arrhythmias in hypertensive patients

Introduction

There is growing evidence suggesting hypertension is related to the occurrence of arrhythmias. When occurring predominantly during the night, two potential entities commonly present in hypertensive patients could be related with increased arrhythmogenesis: (1) the lack of normal nocturnal dipping of blood pressure (BP) (non-dipping pattern of hypertension) or (2) obstructive sleep apnea (OSA). Thus, nocturnal arrhythmias (NAs) can identify hypertensive patients with OSA and/or non-dipping pattern, both related with adverse outcomes.

Aims

To determine if NAs are related with non-dipping hypertension, OSA or both.

Methods

We studied hypertensive patients who performed ambulatory blood pressure monitoring (ABPM) and also polysomnography and 24-hour Holter monitoring. Non-dipping pattern was considered when nocturnal BP reduction was inferior to 10%. Based on Holter monitoring, NAs were present when atrial fibrillation, frequent premature atrial contractions (PACs) (>30 PACs/hour), runs of >4 consecutive PACs, frequent premature ventricular contractions (PVCs) (>30PVCs/hour) or runs of >4 consecutive PVCs were present predominantly during sleeping hours. During polyssonography, apnoea/hypopnoea index (AHI) and oxygen saturation (SaO2) were analysed. Moderate to severe OSA was considered when AHI >15.

Results

We studied 104 patients [median age 62 (54–70) years, 65% male): 42 (40%) had moderate to severe OSA (median AHI=11 (6–26), mean SaO2=94% (92–95)] and 64 (61%) were non-dippers. NAs occurred in 18 patients (17%) and they were independently associated with AHI (Odds Ratio (OR) for a one unit increase 1.04, 95% confidence interval (CI) 1.01–1.07, p=0.03) but not with SaO2 (OR 0.96, CI 0.78–1.19, p=0.73) nor non-dipping pattern (OR 1.23, CI 0.38–3.98, p=0.72). No interaction was found between OSA and non-dipping hypertension (p=0.35). In patients with dipping pattern (n=40), AHI was higher in NAs patients comparing with no NAs patients (median AHI 29 versus 10, p=0.04), while in those with non-dipping pattern (n=64), AHI was not statistically different between patients with and without NAs (21 versus 11, p=0.12) (figure).

Figure 1

Conclusion

In this population of hypertensive patients, the presence of NAs was associated with OSA severity (i.e AHI), but not with the non-dipping pattern of hypertension. The importance of obstructive events in arrhythmogenesis seemed to be more pronounced in dipping patients, suggesting the abnormal high blood pressure during the night may also have some impact on NAs in non-dipping patients. Overall, our results suggest that OSA screening should be considered when nocturnal arrhythmias are detected in hypertensive patients, but ABPM should not be forgotten since multiple mechanisms can be involved in nocturnal arrhythmogenesis.

Dedo Azul Não-Isquémico: Caso Raro e Benigno

O dedo azul não-isquémico espontâneo consiste no aparecimento súbito de uma coloração violácea digital isolada, sem outros sintomas associados e de resolução rápida e espontânea. É um fenómeno raro e benigno e constitui um diagnóstico de exclusão, sendo importante realizar o diagnóstico diferencial com outras etiologias mais frequentes, nomeadamente eventos trombóticos, isquémicos ou patologia autoimune. Descreve-se o caso de uma mulher de 83 anos, que recorreu à consulta de uma unidade de saúde por início súbito de cor violácea e edema do terceiro dedo da mão direita, indolor e sem envolvimento da extremidade distal. A avaliação analítica para trombofilias e autoimunidade revelou-se negativa, assim como a investigação imagiológica de isquemia ou trauma. Ao fim de sete dias a doente foi reavaliada, havendo resolução completa do quadro. Este caso assume importância devido à sua semelhança com patologias de prognóstico potencialmente mais grave.

Ventricular Arrhythmias in Patients with Obstructive Sleep Apnea

Obstructive Sleep Apnea (OSA) is a prevalent condition thought to increase in the future. Being mostly undiagnosed, the most serious complications are cardiovascular diseases, among which are arrhythmias. Controversy remains as to whether OSA is a primary etiologic factor for ventricular arrhythmias, because of the high incidence of cardiovascular comorbidities in OSA patients. Howev-er, there is mostly a strong evidence of a relation between OSA and ventricular arrhythmias. A few mechanisms have been proposed to be responsible for this association and some electrocardiographic changes have also been demonstrated to be more frequent in OSA patients. Treatment of OSA with Continuous Positive Airway Pressure (CPAP) has the potential to reduce arrhythmias and confer a mortality benefit.

Design of gamma-ray spectrometers optimized for fast particle studies at ITER

A set of gamma ray spectrometers has been designed for ITER within the Radial Gamma Ray Spectrometer (RGRS) project. The aim of this project is designing a system, integrated with the ITER radial neutron camera, which is able to measure the gamma-rays emitted from the plasma with a good energy resolution (about 1.5% at 4.44 MeV) and at high counting rates (in excess of 1 MHz). The RGRS will be able to operate both in the D phase and in the full-power DT phase and will measure gamma rays from (i) reactions between fast ions, such as α particles, and light impurities and (ii) bremsstrahlung emission generated by runaway electron interactions with both plasma bulk and tokamak walls. The RGRS detectors are arranged in nine lines of sights (able to cover a radial region with r < a/3), each featuring a large LaBr₃ scintillator crystal. Due to the high neutron flux and magnetic field, several solutions have been adopted to guarantee a good signal to background ratio and MHz counting rate capabilities. The RGRS is capable to combine space and energy distribution measurements of α particles and runaway electrons, which will help the study of the fast particle physics in a burning plasma.