Huntington's Disease: Calcium Dyshomeostasis and Pathology Models

Huntington's disease (HD) is a severe inherited neurodegenerative disorder characterized by motor dysfunction, cognitive decline, and mental impairment. At the molecular level, HD is caused by a mutation in the first exon of the gene encoding the huntingtin protein. The mutation results in an expanded polyglutamine tract at the N-terminus of the huntingtin protein, causing the neurodegenerative pathology. Calcium dyshomeostasis is believed to be one of the main causes of the disease, which underlies the great interest in the problem among experts in molecular physiology. Recent studies have focused on the development of animal and insect HD models, as well as patient-specific induced pluripotent stem cells (HD-iPSCs), to simulate the disease's progression. Despite a sesquicentennial history of HD studies, the issues of diagnosis and manifestation of the disease have remained topical. The present review addresses these issues.

Experimental Study of Thermal Runaway Process of 18650 Lithium-Ion Battery

This study addresses the effects of the SOC (State of Charge) and the charging–discharging process on the thermal runaway of 18650 lithium-ion batteries. A series of experiments were conducted on an electric heating and testing apparatus. The experimental results indicate that 6 W is the critical heating power for 40% SOC. With a 20 W constant heating rate, the thermal runaway initial temperature of the lithium-ion battery decreases with the increasing SOC. The final thermal runaway temperature increases with the SOC when the SOC is lower than 80%. However, a contrary conclusion was obtained when the SOC was higher than 80%. Significant mass loss, accompanied by an intense exothermic reaction, took place under a higher SOC. The critical charging current, beyond which the thermal runaway occurs, was found to be 2.6 A. The thermal runaway initial temperature decreases with the increasing charging current, while the intensity of the exothermic reaction varies inversely. Mass ejection of gas and electrolytes exists during thermal runaway when the charging current is higher than 10.4 A, below which only a large amount of gas is released. The thermal runaway initial temperature of discharging is higher than that of non-discharging.

Potential impacts of climate change on carbon dynamics in a rain-fed agro-ecosystem on the Loess Plateau of China

Although many studies have been conducted on crop yield in rain-fed agriculture, the possible impacts of climate change on the carbon (C) dynamics of rain-fed rotation systems, particularly their direction and magnitude at the long-term scale, are still poorly understood. In this study, the sensitivity of C dynamics of a typical rotation system to elevated CO₂ and changed temperature and precipitation were first tested using the CENTURY model, based on data collected from a 30-year field experiment of a corn-wheat-wheat-millet (CWWM) rotation system in the tableland of the Loess Plateau. The possible responses of crop biomass C and soil organic C (SOC) accumulation were then evaluated under scenarios representing the Representative Concentration Pathways (RCPs) 4.5 and 8.5. The results indicated that elevated CO₂ and increased precipitation exerted positive effect on biomass C in CWWM rotation system, while increasing the temperature by 1°C, 2°C and 4°C had negative effects on biomass C due to opposite responses of corn and winter wheat to warming. SOC accumulation was enhanced by increased CO₂ concentration and precipitation but impaired by increased temperature. Under future RCP scenarios with dynamic CO₂, the biomass C of corn exhibited decrease during the period of 2046-2075 under RCP4.5 and the period of 2016-2075 under RCP8.5 due to reduced precipitation and a warmer climate. In contrast, winter wheat would benefit from increased CO₂ and temperature and was projected to have larger biomass C under both RCP scenarios. Although the climate condition had large differences between RCP4.5 and RCP8.5, the projected SOC had similar trends under two scenarios due to CO₂ fertilizer effect and precipitation fluctuation. These results implied that crop biomass C and SOC accumulation in a warmer environment are strongly related to precipitation, and increase in field water storage should be emphasized in coping with future climate.

Potential of temperate agricultural soils for carbon sequestration: A meta-analysis of land-use effects

Restoring depleted soil organic carbon (SOC) stocks of arable land to remove carbon from the atmosphere and offset fossil fuel emissions is a promising strategy for the mitigation of climate change. In agroecosystems conservational tillage practices and the abandonment of formerly plowed fields (ex-arable land) are shown to have the highest potential to sequester SOC. Nevertheless reported sequestration rates vary and the effects of environmental site conditions remain poorly understood. Our results are based on a meta-analysis of 273 paired SOC estimates from 65 publications which included only mineral soils from the temperate zone. SOC stocks of ex-arable grasslands with an average of 14years since abandonment were 18% larger compared to the SOC of arable land. Likewise, SOC stocks of never-plowed grassland plots were 11% larger than the SOC stocks of abandoned fields. The average sequestration rate was 0.72t Cha(-1)yr(-1). Semi-arid and sub-humid climate as well as low initial SOC stocks positively affected proportional SOC gains suggesting that the recovery of carbon stocks is not limited by low primary production. Therefore, the northward shift of cultivation areas in the temperate zone will lead to the abandonment of soils with high SOC recovery potential. However, if native soils are opened up elsewhere to compensate for yield losses due to abandonment the surplus of SOC in ex-arable land can easily be overcompensated by cultivation losses.

How do soil organic carbon stocks change after cropland abandonment in Mediterranean humid mountain areas?

The effects of land use changes on soil carbon stocks are a matter of concern stated in international policy agendas on the mitigation of greenhouse emissions. Afforestation is increasingly viewed as an environmental restorative land use change prescription and is considered one of the most efficient carbon sequestration strategies currently available. Given the large quantity of CO2 that soils release annually, it is important to understand disturbances in vegetation and soil resulting from land use changes. The main objective of this study is to assess the effects of land abandonment, land use change and afforestation practices on soil organic carbon (SOC) dynamics. For this aim, five different land covers (bare soil, permanent pastureland, secondary succession, Pinus sylvestris (PS) and Pinus nigra (PN) afforestation), in the Central Spanish Pyrenees, were analysed. SOC dynamics have been studied in the bulk soil, and in the fractions separated according to two methodologies: (i) aggregate size distribution, and (ii) density fractionation, and rates of carbon mineralization have been determined by measuring CO2 evolution using an automated respirometer. The results showed that: (i) SOC contents were higher in the PN sites in the topsoil (10cm), (ii) when all the profiles were considered no significant differences were observed between pastureland and PN, (iii) SOC accumulation under secondary succession is a slow process, and (iv) pastureland should also be considered due to the relative importance in SOC stocks. The first step of SOC stabilization after afforestation is the formation of macro-aggregates promoted by large inputs of SOC, with a high contribution of labile organic matter. However, our respiration experiments did not show evidence of SOC stabilization. SOC mineralization was higher in the top layers and values decreased with depth. These results gain insights into which type of land management is most appropriate after land abandonment for SOC.

A Rolling Stone Gathers No Moss-The Long Way from Good Intentions to Physical Activity Mediated by Planning, Social Support, and Self-Regulation

Background: Although many people know that an active lifestyle contributes to health they fail to translate their intentions into action. This has been explained by deficits in self-management and resources, such as enabling social support, planning, and self-regulation in the face of barriers. The present study examines the role of perceived social support, planning, and self-regulation in facilitating physical activity.

Methods: In a prospective online study, intention was assessed at baseline (Time 1), planning and social support at 4-week follow-up (Time 2), self-regulation and physical activity at 6-month follow-up (Time 3). A path analysis was conducted to shed light on mediating psychological mechanisms contributing to maintenance of physical activity.

Results: Perceived support (Time 2), planning (Time 2), and self-regulation (Time 3) mediated the link from intention (Time 1) to physical activity (Time 3); the specific and total indirect effects were significant.

Conclusions: Findings suggest that perceived social support, planning, and self-regulation can bridge the intention-behavior gap. Behavior change interventions should target those mechanisms in vulnerable individuals.

Recent developments in choledochoscopy: technical and clinical advances

Peroral cholangioscopy has become an important tool in the diagnosis and treatment of a variety of biliary diseases, ranging from indeterminate biliary strictures to bile duct stones. Although the first cholangioscopy was performed in the 1970s, recent technological advances have provided us with cholangioscopes that yield high-resolution images, possess single-operator capability, and have ultrathin design to allow easier maneuverability and detailed imaging of the biliary tract. We review here the currently available devices for peroral cholangioscopy, their clinical applications, limitations, and complications.

Effects of cyclopiazonic acid and dexamethasone on serotonin-induced calcium responses in vascular smooth muscle cells

We previously observed that sarcoendoplasmic reticulum Ca(2+) ATPase (SERCA) blockade by cyclopiazonic acid (CPA) significantly potentiates serotonin (5-hydroxytryptamine (5-HT))-induced vascular contractions. Furthermore, 5-HT receptor antagonist methysergide partially inhibited CPA-potentiated 5-HT contractions. In the present study, we further investigated whether SERCA inhibition potentiates 5-HT-induced Ca(2+) responses along with attenuating the receptor antagonism by store-operated Ca(2+) (SOC) entry and protein kinase C (PKC)-mediated mechanisms. The effects of dexamethasone that was previously shown to induce SOC entry and enhance 5-HT responses were also tested. For this purpose, intracellular Ca(2+) levels were monitored in A7r5 embryonic rat vascular smooth muscle cells by spectrofluorometry using the fluorescent indicator fura-2. The results showed that CPA, although not dexamethasone, significantly potentiated 5-HT-induced Ca(2+) elevations. Ketanserin partially decreased 5-HT-induced and CPA-potentiated Ca(2+) elevations whereas both PKC inhibitor D-sphingosine and SOC entry blocker 2-aminoethoxydiphenyl borate (2-APB) abolished the remaining responses. The data suggests that diminished antagonistic effect on 5-HT-induced Ca(2+) elevations in the presence of SERCA inhibition is induced by SOC entry and PKC activation.

Polychlorinated naphthalenes (PCNs) in Chinese forest soil: Will combustion become a major source?

We collected O- and A-horizon soil samples in 26 Chinese mountainous forests to investigate the content, spatial pattern, and potential sources of polychlorinated naphthalenes (PCNs). Spatial patterns were influenced mainly by the approximation to sources and soil organic contents. High concentrations often occurred close to populated or industrialized areas. Combustion-related activities contributed to PCN pollution. Relatively high proportions of CN-73 in northern China may be attributed to coke consumption, while CN-51 could be an indicator of biomass burning in Southwest China. There are evidences that PCNs may largely derived from unintentional production. If uncontrolled, UP-PCN (unintentionally produced PCNs) emissions could increase with industrial development. The abnormally high concentrations at Gongga and Changbai Mountains appear to be associated with the high efficient of forest filter of atmospheric contaminants at these densely forested sites. We question whether this is caused by ecotones between forests, and raise additional questions for future analyses.

Stability of the 13-item sense of coherence (SOC) scale: a longitudinal prospective study in women treated for breast cancer

PURPOSES

To test the stability of the SOC scale over time and to test the stability of the latent construct in 417 breast cancer patients at the time of diagnosis, after 1 year and in a subsample (n = 80) also 2 and 3 years later.

METHODS

The 13-item SOC scale was firstly tested with mean values and ICC over time and secondly explored with cross-sectional factor analysis, separately for two time points (baseline and after 1 year), followed by a longitudinal factor analyses.

RESULTS

Our results provide support for the stability over time (ICC 0.68, effect size 0.06). The cross-sectional factor analysis revealed a modified three-factor and a second-order factor model meeting criteria for goodness of fit. The longitudinal modified second-order factor model confirmed the construct stability character of the SOC scale with an acceptable goodness-of-fit criteria; X (2)/df = 2.91; GFI = 0.87; RMSEA = 0.07; CFI = 0.84; AIC = 962.3. The proportion of variance (R (2)) was 0.42.

CONCLUSIONS

The SOC scale is stable over time when applied to women with breast cancer. The longitudinal factor analysis gives support of a stable latent construct in the second-order factor model, allowing for merging all items to one scale reflecting the theoretical construct of SOC. Measurement errors between some items challenge future studies on alternative factor structures.

Self-Regulatory Strategies in Daily Life: Selection, Optimization, and Compensation and Everyday Memory Problems

The effective use of self-regulatory strategies, such as selection, optimization, and compensation (SOC) requires resources. However, it is theorized that SOC use is most advantageous for those experiencing losses and diminishing resources. The present study explored this seeming paradox within the context of limitations or constraints due to aging, low cognitive resources, and daily stress in relation to everyday memory problems. We examined whether SOC usage varied by age and level of constraints, and if the relationship between resources and memory problems was mitigated by SOC usage. A daily diary paradigm was used to explore day-to-day fluctuations in these relationships. Participants (n=145, ages 22 to 94) completed a baseline interview and a daily diary for seven consecutive days. Multilevel models examined between- and within-person relationships between daily SOC use, daily stressors, cognitive resources, and everyday memory problems. Middle-aged adults had the highest SOC usage, although older adults also showed high SOC use if they had high cognitive resources. More SOC strategies were used on high stress compared to low stress days. Moreover, the relationship between daily stress and memory problems was buffered by daily SOC use, such that on high-stress days, those who used more SOC strategies reported fewer memory problems than participants who used fewer SOC strategies. The paradox of resources and SOC use can be qualified by the type of resource-limitation. Deficits in global resources were not tied to SOC usage or benefits. Conversely, under daily constraints tied to stress, the use of SOC increased and led to fewer memory problems.

Blood Pressure and Heart Rate Alterations through Music in Patients Undergoing Cataract Surgery in Greece

INTRODUCTION

Music has been proposed as a safe, inexpensive, nonpharmacological antistress intervention. The purpose of this study was to determine whether patients undergoing cataract surgery while listening to meditation music experience lower levels of blood pressure and heart rate.

METHODS

Two hundred individuals undergoing cataract surgery participated in the study. Hundred individuals listened to meditation music, through headphones, before and during the operation (intervention group) and 100 individuals received standard care (control group). Patients stress coping skills were measured by the Sense of Coherence Scale (SOC Scale). Systolic and diastolic blood pressure and heart rate were defined as outcome measures.

RESULTS

According to the SOC Scale, both groups had similar stress coping skills (mean score: 127.6 for the intervention group and 127.3 for the control group). Before entering the operating room (OR) as well as during surgery the rise in systolic and diastolic pressures was significantly lower in the intervention group (P < 0.001). Among patients receiving antihypertensive therapy, those in the intervention group presented a lower increase only in systolic pressure (P < 0.001) at both time recordings. For those patients in the intervention group who did not receive antihypertensive treatment, lower systolic blood pressure at both time recordings was recorded (P < 0.001) while lower diastolic pressure was observed only during entry to the OR (P = 0.021). Heart rate was not altered between the two groups in any of the recordings.

CONCLUSIONS

Meditation music influenced patients’ preoperative stress with regard to systolic blood pressure. This kind of music can be used as an alternative or complementary method for blood pressure stabilizing in patients undergoing cataract surgery.

STIM1 and STIM2 proteins differently regulate endogenous store-operated channels in HEK293 cells

The endoplasmic reticulum calcium sensors stromal interaction molecules 1 and 2 (STIM1 and STIM2) are key modulators of store-operated calcium entry. Both these sensors play a major role in physiological functions in normal tissue and in pathology, but available data on native STIM2-regulated plasma membrane channels are scarce. Only a few studies have recorded STIM2-induced CRAC (calcium release-activated calcium) currents. On the other hand, many cell types display store-operated currents different from CRAC. The STIM1 protein regulates not only CRAC but also transient receptor potential canonical (TRPC) channels, but it has remained unclear whether STIM2 is capable of regulating store-operated non-CRAC channels. Here we present for the first time experimental evidence for the existence of endogenous non-CRAC STIM2-regulated channels. As shown in single-channel patch clamp experiments on HEK293 cells, selective activation of native STIM2 proteins or STIM2 overexpression results in store-operated activation of Imin channels, whereas STIM1 activation blocks this process. Changes in the ratio between active STIM2 and STIM1 proteins can switch the regulation of Imin channels between store-operated and store-independent modes. We have previously characterized electrophysiological properties of different Ca(2+) influx channels coexisting in HEK293 cells. The results of this study show that STIM1 and STIM2 differ in the ability to activate these store-operated channels; Imin channels are regulated by STIM2, TRPC3-containing INS channels are induced by STIM1, and TRPC1-composed Imax channels are activated by both STIM1 and STIM2. These new data about cross-talk between STIM1 and STIM2 and their different roles in store-operated channel activation are indicative of an additional level in the regulation of store-operated calcium entry pathways.

Interobserver agreement for evaluation of imaging with single operator choledochoscopy: what are we looking at?

BACKGROUND

Single operator choledochoscopy is a platform used to assist in the confirmation of diagnosis of biliary lesions. However, there are little data regarding the interobserver agreement of imaging interpretation. Our objective was to assess the interobserver agreement in single operator choledochoscopy interpretation.

METHODS

38 De-identified SPY Choledochoscopy video clips were sent to 7 interventional endoscopists. They were asked to score the videos on presence of four criteria selected by the investigators: growth, stricture, hyperplasia, and ulceration. Observers also chose a final diagnosis from the categories of cancer, hyperplasia, inflammation, or normal. Kappa scores were calculated for the scoring of the four criteria and for the selection of the final diagnosis.

RESULTS

The overall interobserver agreement was fair in scoring for the presence of a growth (K=0.28, SE 0.035) and stricture (K=0.32, SE 0.035). Scoring for ulceration was slight to fair (K=0.17, SE 0.035). There was only slight agreement for the presence of hyperplasia (K=0.11, SE 0.035); and presumed final diagnosis based on imaging (K=0.18, SE 0.022).

CONCLUSION

The results of this study support the need for an effort to identify and validate cholangioscopy imaging criteria for biliary pathology. This may assist in improving the reliability of the diagnostic value of cholangioscopy as its use becomes more widespread.

KCa and Ca(2+) channels: the complex thought

Potassium channels belong to the largest and the most diverse super-families of ion channels. Among them, Ca(2+)-activated K(+) channels (KCa) comprise many members. Based on their single channel conductance they are divided into three subfamilies: big conductance (BKCa), intermediate conductance (IKCa) and small conductance (SKCa; SK1, SK2 and SK3). Ca(2+) channels are divided into two main families, voltage gated/voltage dependent Ca(2+) channels and non-voltage gated/voltage independent Ca(2+) channels. Based on their electrophysiological and pharmacological properties and on the tissue where there are expressed, voltage gated Ca(2+) channels (Cav) are divided into 5 families: T-type, L-type, N-type, P/Q-type and R-type Ca(2+). Non-voltage gated Ca(2+) channels comprise the TRP (TRPC, TRPV, TRPM, TRPA, TRPP, TRPML and TRPN) and Orai (Orai1 to Orai3) families and their partners STIM (STIM1 to STIM2). A depolarization is needed to activate voltage-gated Ca(2+) channels while non-voltage gated Ca(2+) channels are activated by Ca(2+) depletion of the endoplasmic reticulum stores (SOCs) or by receptors (ROCs). These two Ca(2+) channel families also control constitutive Ca(2+) entries. For reducing the energy consumption and for the fine regulation of Ca(2+), KCa and Ca(2+) channels appear associated as complexes in excitable and non-excitable cells. Interestingly, there is now evidence that KCa-Ca(2+) channel complexes are also found in cancer cells and contribute to cancer-associated functions such as cell proliferation, cell migration and the capacity to develop metastases. This article is part of a Special Issue entitled: Calcium signaling in health and disease. Guest Editors: Geert Bultynck, Jacques Haiech, Claus W. Heizmann, Joachim Krebs, and Marc Moreau.

Everyday experiences of memory problems and control: the adaptive role of selective optimization with compensation in the context of memory decline

The present study examined the role of long-term working memory decline in the relationship between everyday experiences of memory problems and perceived control, and we also considered whether the use of accommodative strategies [selective optimization with compensation (SOC)] would be adaptive. The study included Boston-area participants (n = 103) from the Midlife in the United States study (MIDUS) who completed two working memory assessments over 10 years and weekly diaries following Time 2. In adjusted multi-level analyses, greater memory decline and lower general perceived control were associated with more everyday memory problems. Low perceived control reported in a weekly diary was associated with more everyday memory problems among those with greater memory decline and low SOC strategy use (Est. = -0.28, SE= 0.13, p = .036). These results suggest that the use of SOC strategies in the context of declining memory may help to buffer the negative effects of low perceived control on everyday memory.

Development and validation of two liquid chromatography-tandem mass spectrometry methods for the determination of silibinin and silibinin hemisuccinate in human plasma

To investigate the pharmacokinetics of silibinin and silibinin hemisuccinate in human plasma, two high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) methods were developed and validated. The methods require a small volume of sample (100μL), and the recovery of the analytes was complete with a good reproducibility (CV% 1.7-9.5), after a simple protein precipitation. Naringenin was used as internal standard. The chromatographic methods provided a good separation of diastereoisomers A and B of both silibinin and silibinin hemisuccinate onto a Chromolith Performance RP18e 100mm×3mm column, with a resolution of peaks from plasma matrix in less than 6min. The methods precision values expressed as CV% were always ≤6.2% and the accuracy was always well within the acceptable 15% range. Quantification was performed on a triple-quadrupole tandem mass spectrometer by Selected Reaction Monitoring (SRM) mode, in a negative ion mode, via electrospray ionization (ESI). The lower limit of quantitation was set at 5.0ng/mL (silibinin) and 25.0ng/mL (silibinin hemisuccinate), and the linearity was validated up to 1000.0 and 12,500.0ng/mL, for silibinin and silibinin hemisuccinate, respectively, with correlation coefficients (R(2)) of 0.991 or better. The methods were suitable for pharmacokinetic studies and were successfully applied to human plasma samples from subjects treated intravenously with Legalon(®) SIL at the dose of 20mg/kg, expressed as silibinin.

STIM1 Protein Activates Store-Operated Calcium Channels in Cellular Model of Huntington's Disease

We have shown that the expression of full-length mutated huntingtin in human neuroblastoma cells (SK-N-SH) leads to an abnormal increase in calcium entry through store-operated channels. In this paper, the expression of the N-terminal fragment of mutated huntingtin (Htt138Q-1exon) is shown to be enough to provide an actual model for Huntington's disease. We have shown that Htt138Q-1exon expression causes increased store-operated calcium entry, which is mediated by at least two types of channels in SK-N-SH cells with different reversal potentials. Calcium sensor, STIM1, is required for activation of store-operated calcium entry in these cells. The results provide grounds for considering the proteins responsible for the activation and maintenance of the store-operated calcium entry as promising targets for developing novel therapeutics for neurodegenerative diseases.

Protein engineering of Cas9 for enhanced function

CRISPR/Cas systems act to protect the cell from invading nucleic acids in many bacteria and archaea. The bacterial immune protein Cas9 is a component of one of these CRISPR/Cas systems and has recently been adapted as a tool for genome editing. Cas9 is easily targeted to bind and cleave a DNA sequence via a complementary RNA; this straightforward programmability has gained Cas9 rapid acceptance in the field of genetic engineering. While this technology has developed quickly, a number of challenges regarding Cas9 specificity, efficiency, fusion protein function, and spatiotemporal control within the cell remain. In this work, we develop a platform for constructing novel proteins to address these open questions. We demonstrate methods to either screen or select active Cas9 mutants and use the screening technique to isolate functional Cas9 variants with a heterologous PDZ domain inserted within the protein. As a proof of concept, these methods lay the groundwork for the future construction of diverse Cas9 proteins. Straightforward and accessible techniques for genetic editing are helping to elucidate biology in new and exciting ways; a platform to engineer new functionalities into Cas9 will help forge the next generation of genome-modifying tools.

Sense of coherence, health problems, and presenteeism in Japanese university students

AIM

Sense of coherence (SOC) is thought to be a major determinant in maintaining health. SOC gained attention recently in the fields of psychiatry after it was reported to be associated with a lowered risk of various health problems. However, the effect of SOC as a buffer against performance impairment caused by health problems is not well known. Thus, we aimed to examine the relationships among health problem, the degree of presenteeism (performance loss due to health problems), and SOC in adolescents.

METHODS

Participants were 2824 university students (1855 males, mean age; 18.35±0.84 years). SOC and self-reported health problems were assessed using an SOC scale (29 items) and the presenteeism scale for students, respectively.

RESULTS

SOC scores differed between students with and without health problems (t(2822)=5.75, P<0.001). The effect size (Cohen's d) was 0.22 for this difference. In a multiple logistic regression analysis, male gender (odds ratio [OR]=0.62; 95% confidence interval [CI]=0.53-0.73), moderate SOC (within ±1 SD; OR=0.59; 95% CI=0.47-0.72), and high SOC (>1 SD; OR=0.43; 95% CI=0.33-0.58) were independently associated with a lower frequently of health problems. In addition, SOC showed a significant inverse correlation with presenteeism (r=-0.27, P<0.001).

CONCLUSION

These results suggest that application of the concept of SOC might aid in the prevention of health problems among university students. Students with a strong SOC might be less prone to a decline in performance when health problems arise.

Longitudinal assessment of liver stiffness in patients undergoing antiviral treatment for hepatitis C

BACKGROUND

Liver stiffness has been suggested as a parameter of fibrosis progression/regression in hepatitis C virus (HCV) patients.

AIM

To evaluate stiffness before and after peginterferon-ribavirin treatment.

METHODS

Stiffness was prospectively measured in 74 HCV patients, 32 genotypes 1/4 (43.25%) and 42 genotypes 2/3 (56.75%), before, at end of treatment, and after 3 years of follow-up (49 patients). On the same study day, 21 patients underwent liver biopsy.

RESULTS

In 55 patients with sustained virological response (74.32%), liver stiffness decreased significantly at end of therapy (6.8±4.9kPa) vs. baseline (9.5±6.9kPa, p=0.04). The decrease vs. baseline was maintained in 30 sustained virological response patients after 3 years follow-up (6.8±4.6kPa vs. 10.8±8.5kPa, p=0.0141). No difference was found at end of treatment vs. baseline (10.1±4.7kPa vs. 9.7±4.2kPa, p=0.825) and after 3 years of follow-up vs. baseline (10.2±3.4kPa vs. 9.7±4.2kPa, p=0.765) in null responders. Similar results were found in relapsers at end of treatment vs. baseline (13.7±7.7kPa vs. 15.2±8.2kPa, p=0.74), and after 3 years of follow-up vs. baseline (16.9±10.0kPa vs. 15.2±8.2kPa, p=0.734). Pre-treatment stiffness >12kPa was significantly associated with no SVR (p<0.025), RR=2.44 (95%C.I. 1.17-5.07).

CONCLUSION

Liver stiffness may be useful to assess long-term antiviral treatment response.

Short-term reduction in intrinsic heart rate during biventricular pacing after cardiac surgery: a substudy of a randomized clinical trial

BACKGROUND

The Biventricular Pacing After Cardiac Surgery trial investigates hemodynamics of temporary pacing in selected patients at risk of left ventricular dysfunction. This trial demonstrates improved hemodynamics during optimized biventricular pacing compared with atrial pacing at the same heart rate 1 and 2 hours after bypass and reduced vasoactive-inotropic score over the first 4 hours after bypass. However, this advantage of biventricular versus atrial pacing disappears 12 to 24 hours later. We hypothesized that changes in intrinsic heart rate can explain variable effects of atrial pacing in this setting.

METHODS

Heart rate, mean arterial pressure, cardiac output, and medications depressing heart rate were analyzed in patients randomized to continuous biventricular pacing (n = 16) or standard of care (n = 18).

RESULTS

During 30-second testing periods without pacing, intrinsic heart rate was lower in the paced group 12 to 24 hours after bypass (76.5 ± 17.5 vs 91.7 ± 13.0 beats per minute; P = .040) but not 1 or 2 hours after bypass. Cardiac output (4.4 ± 1.2 vs 3.6 ± 1.9 L/min; P = .054) and stroke volume (53 ± 2 vs 42 ± 2 mL; P = .051) increased overnight in the paced group. Vasoactive medication doses were not different between groups, whereas dexmedetomidine administration was prolonged over postoperative hours 12 to 24 in the paced group (793 ± 528 vs 478 ± 295 minutes; P = .013).

CONCLUSIONS

These observations suggest that hemodynamic benefits of biventricular pacing 12 to 24 hours after cardiopulmonary bypass lead to withdrawal of sympathetic drive and decreased intrinsic heart rate. Depression of intrinsic rate increases the apparent benefit of atrial pacing in the chronically paced group but not in the control group. Additional study is needed to define clinical benefits of these effects.

Chemical constituents of fine particulate air pollution and pulmonary function in healthy adults: the Healthy Volunteer Natural Relocation study

The study examined the associations of 32 chemical constituents of particulate matter with an aerodynamic diameter ≤2.5 μm (PM₂.₅) with pulmonary function in a panel of 21 college students. Study subjects relocated from a suburban area to an urban area with changing ambient air pollution levels and contents in Beijing, China, and provided daily morning/evening peak expiratory flow (PEF) and forced expiratory volume in 1s (FEV₂₁) measurements over 6 months in three study periods. There were significant reductions in evening PEF and morning/evening FEV₂₁ associated with various air pollutants and PM₂.₅ constituents. Four PM₂.₅ constituents (copper, cadmium, arsenic and stannum) were found to be most consistently associated with the reductions in these pulmonary function measures. These findings provide clues for the respiratory effects of specific particulate chemical constituents in the context of urban air pollution.