Metabolic engineering of Caldicellulosiruptor bescii for hydrogen production

Hydrogen is an alternative fuel for transportation vehicles because it is clean, sustainable, and highly flammable. However, the production of hydrogen from lignocellulosic biomass by microorganisms presents challenges. This microbial process involves multiple complex steps, including thermal, chemical, and mechanical treatment of biomass to remove hemicellulose and lignin, as well as enzymatic hydrolysis to solubilize the plant cell walls. These steps not only incur costs but also result in the production of toxic hydrolysates, which inhibit microbial growth. A hyper-thermophilic bacterium of Caldicellulosiruptor bescii can produce hydrogen by decomposing and fermenting plant biomass without the need for conventional pretreatment. It is considered as a consolidated bioprocessing (CBP) microorganism. This review summarizes the basic scientific knowledge and hydrogen-producing capacity of C. bescii. Its genetic system and metabolic engineering strategies to improve hydrogen production are also discussed. KEY POINTS: • Hydrogen is an alternative and eco-friendly fuel. • Caldicellulosiruptor bescii produces hydrogen with a high yield in nature. • Metabolic engineering can make C. bescii to improve hydrogen production.

Hydrogen Production from Barley Straw and Miscanthus by the Hyperthermophilic Bacterium, Cadicellulosirupter bescii

This work aimed to evaluate the feasibility of biohydrogen production from Barley Straw and Miscanthus. The primary obstacle in plant biomass decomposition is the recalcitrance of the biomass itself. Plant cell walls consist of cellulose, hemicellulose, and lignin, which make the plant robust to decomposition. However, the hyperthermophilic bacterium, Caldicellulosiruptor bescii, can efficiently utilize lignocellulosic feedstocks (Barley Straw and Miscanthus) for energy production, and C. bescii can now be metabolically engineered or isolated to produce more hydrogen and other biochemicals. In the present study, two strains, C. bescii JWCB001 (wild-type) and JWCB018 (ΔpyrFA Δldh ΔcbeI), were tested for their ability to increase hydrogen production from Barley Straw and Miscanthus. The JWCB018 resulted in a redirection of carbon and electron (carried by NADH) flow from lactate production to acetate and hydrogen production. JWCB018 produced ~54% and 63% more acetate and hydrogen from Barley Straw, respectively than its wild-type counterpart, JWCB001. Also, 25% more hydrogen from Miscanthus was obtained by the JWCB018 strain with 33% more acetate relative to JWCB001. It was supported that the engineered C. bescii, such as the JWCB018, can be a parental strain to get more hydrogen and other biochemicals from various biomass.

Comprehensive Characterization of Mutant Pichia stipitis Co-Fermenting Cellobiose and Xylose through Genomic and Transcriptomic Analyses

The development of a yeast strain capable of fermenting mixed sugars efficiently is crucial for producing biofuels and value-added materials from cellulosic biomass. Previously, a mutant Pichia stipitis YN14 strain capable of co-fermenting xylose and cellobiose was developed through evolutionary engineering of the wild-type P. stipitis CBS6054 strain, which was incapable of cofermenting xylose and cellobiose. In this study, through genomic and transcriptomic analyses, we sought to investigate the reasons for the improved sugar metabolic performance of the mutant YN14 strain in comparison with the parental CBS6054 strain. Unfortunately, comparative wholegenome sequencing (WGS) showed no mutation in any of the genes involved in the cellobiose metabolism between the two strains. However, comparative RNA sequencing (RNA-seq) revealed that the YN14 strain had 101.2 times and 5.9 times higher expression levels of HXT2.3 and BGL2 genes involved in cellobiose metabolism, and 6.9 times and 75.9 times lower expression levels of COX17 and SOD2.2 genes involved in respiration, respectively, compared with the CBS6054 strain. This may explain how the YN14 strain enhanced cellobiose metabolic performance and shifted the direction of cellobiose metabolic flux from respiration to fermentation in the presence of cellobiose compared with the CBS6054 strain.

Valorization of CO2 to β-farnesene in Rhodobacter sphaeroides

The valorization of CO₂ into valuable products is a sustainable strategy to help overcome the climate crisis. In particular, biological conversion is attractive as it can produce long-chain hydrocarbons such as terpenoids. This study reports the high yield of β-farnesene production from CO₂ by expressing heterologous β-farnesene synthase (FS) into Rhodobacter sphaeroides. To increase the expression of FS, a strong active promoter and a ribosome binding site (RBS) were engineered. Moreover, β-farnesene production was improved further through the supply of exogenous antioxidants and additional nutrients. Finally, β-farnesene was produced from CO₂ at a titer of 44.53 mg/L and yield of 234.08 mg/g, values that were correspondingly 23 times and 46 times higher than those from the initial production of β-farnesene. Altogether, the results here suggest that the autotrophic production of β-farnesene can provide a starting point for achieving a circular carbon economy.

Regulation of Reactive Oxygen Species Promotes Growth and Carotenoid Production Under Autotrophic Conditions in Rhodobacter sphaeroides

Industrial demand for capture and utilization using microorganisms to reduce CO₂, a major cause of global warming, is significantly increasing. Rhodobacter sphaeroides is a suitable strain for the process of converting CO₂ into high-value materials because it can accept CO₂ and has various metabolic pathways. However, it has been mainly studied for heterotrophic growth that uses sugars and organic acids as carbon sources, not autotrophic growth. Here, we report that the regulation of reactive oxygen species is critical for growth when using CO₂ as a sole carbon source in R. sphaeroides. In general, the growth rate is much slower under autotrophic conditions compared to heterotrophic conditions. To improve this, we performed random mutagenesis using N-methyl-N’-nitro-N-nitrosoguanidine (NTG). As a result, we selected the YR-1 strain with a maximum specific growth rate (μ) 1.44 day^–1 in the early growth phase, which has a 110% faster growth rate compared to the wild-type. Based on the transcriptome analysis, it was confirmed that the growth was more sensitive to reactive oxygen species under autotrophic conditions. In the YR-1 mutant, the endogenous contents of H₂O₂ levels and oxidative damage were reduced by 33.3 and 42.7% in the cells, respectively. Furthermore, we measured that concentrations of carotenoids, which are important antioxidants. The total carotenoid is produced 9.63 g/L in the YR-1 mutant, suggesting that the production is 1.7-fold higher than wild-type. Taken together, our observations indicate that controlling ROS promotes cell growth and carotenoid production under autotrophic conditions.

Effects of Engineered Saccharomyces cerevisiae Fermenting Cellobiose through Low-Energy-Consuming Phosphorolytic Pathway in Simultaneous Saccharification and Fermentation

Until recently, four types of cellobiose-fermenting Saccharomyces cerevisiae strains have been developed by introduction of a cellobiose metabolic pathway based on either intracellular β-glucosidase (GH1-1) or cellobiose phosphorylase (CBP), along with either an energy-consuming active cellodextrin transporter (CDT-1) or a non-energy-consuming passive cellodextrin facilitator (CDT-2). In this study, the ethanol production performance of two cellobiose-fermenting S. cerevisiae strains expressing mutant CDT-2 (N306I) with GH1-1 or CBP were compared with two cellobiose-fermenting S. cerevisiae strains expressing mutant CDT-1 (F213L) with GH1-1 or CBP in the simultaneous saccharification and fermentation (SSF) of cellulose under various conditions. It was found that, regardless of the SSF conditions, the phosphorolytic cellobiose-fermenting S. cerevisiae expressing mutant CDT-2 with CBP showed the best ethanol production among the four strains. In addition, during SSF contaminated by lactic acid bacteria, the phosphorolytic cellobiose-fermenting S. cerevisiae expressing mutant CDT-2 with CBP showed the highest ethanol production and the lowest lactate formation compared with those of other strains, such as the hydrolytic cellobiose-fermenting S. cerevisiae expressing mutant CDT-1 with GH1-1, and the glucose-fermenting S. cerevisiae with extracellular β-glucosidase. These results suggest that the cellobiose-fermenting yeast strain exhibiting low energy consumption can enhance the efficiency of the SSF of cellulosic biomass.

Observation of Cellodextrin Accumulation Resulted from Non-Conventional Secretion of Intracellular β-Glucosidase by Engineered Saccharomyces cerevisiae Fermenting Cellobiose

Although engineered Saccharomyces cerevisiae fermenting cellobiose is useful for the production of biofuels from cellulosic biomass, cellodextrin accumulation is one of the main problems reducing ethanol yield and productivity in cellobiose fermentation with S. cerevisiae expressing cellodextrin transporter (CDT) and intracellular β-glucosidase (GH1-1). In this study, we investigated the reason for the cellodextrin accumulation and how to alleviate its formation during cellobiose fermentation using engineered S. cerevisiae fermenting cellobiose. From the series of cellobiose fermentation using S. cerevisiae expressing only GH1-1 under several culture conditions, it was discovered that small amounts of GH1-1 were secreted and cellodextrin was generated through trans-glycosylation activity of the secreted GH1-1. As GH1-1 does not have a secretion signal peptide, non-conventional protein secretion might facilitate the secretion of GH1-1. In cellobiose fermentations with S. cerevisiae expressing only GH1-1, knockout of TLG2 gene involved in non-conventional protein secretion pathway significantly delayed cellodextrin formation by reducing the secretion of GH1-1 by more than 50%. However, in cellobiose fermentations with S. cerevisiae expressing both GH1-1 and CDT-1, TLG2 knockout did not show a significant effect on cellodextrin formation, although secretion of GH1-1 was reduced by more than 40%. These results suggest that the development of new intracellular β-glucosidase, not influenced by non-conventional protein secretion, is required for better cellobiose fermentation performances of engineered S. cerevisiae fermenting cellobiose.

Different effects on right ventricular function in different etiology of secondary tricuspid regurgitation

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Ministry of Science and Technology, Excutive Yuan, Taiwan

Background

Tricuspid regurgitation (TR) is traditionally classified as primary or secondary TR. The effects of TR on right ventricular (RV) function were not consistent. We hypothesized that secondary TR is not a unique group, sophisticated sub-grouping can be useful for studying effects of TR on RV function.

Methods

207 consecutive patients identified as significant TR (moderate and severe) by echocardiography were recruited. Standard measurements for right heart were done according to guideline. Lateral tricuspid annulus systolic tissue velocity (S’) and RV fractional area change (FAC) were used for RV function. We classified these patients into primary TR and 6 subgroups of secondary TR according to a new systemic approach.

Results

Mean age of subjects was 71.2 ± 14.7 years, and there were 84 (40.6%) male. There were 29 (14%) primary TR. Secondary TR was further classified into 6 groups included 18 (8.7%) pacemaker related, 81 (39.1 %) left heart diseases, 6 (2.9%) congenital heart diseases, 3 (1.4%) RV myopathy, 27 (13.0%) pulmonary hypertension, and 43 (20.8%) idiopathic TR. Among 4 major groups (congenital heart disease and RV myopathy were not included in analysis due to low numbers) of secondary TR, S’ was significant higher in idiopathic TR and RV FAC were higher in pacemaker related and idiopathic TR. RV dysfunction was defined as FAC < 35%. RV dysfunction presented mostly in pulmonary hypertension related TR and leastly in idiopathic TR (59.3% vs. 14%, p <0.001). Multivariate analysis using idiopathic TR as reference and controlled TR maximal velocity, RV end-diastolic area, right atrial area, and severity of TR, left heart disease related TR had higher risk of RV dysfunction (OR 4.178, 95% CI 1.490-11.703, p = 0.007).

Conclusions

Effects of TR on RV function were different among different subgroups of secondary TR. Left heart disease related TR had highest risk for RV dysfunction. Secondary TR should not be regarded as a single disease.

Characteristics of idiopathic tricuspid regurgitation

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Ministry of Science and Technology, Executive Yuan, Taiwan

Background

Tricuspid regurgitation (TR) were traditionally classified as primary and secondary TR. Recently a new category of TR was developed and named as idiopathic TR. However, diagnosis and characteristics of idiopathic TR were not consisted. We tried to identify idiopathic TR by a new systemic approach and studied its characteristics.

Methods

207 consecutive patients (mean age 71.2 ± 14.7 years, 40.6% male) identified as significant TR (moderate and severe) by echocardiography were recruited. We classified TR by a new systemic approach. The classification process started from identified primary TR, then pacemaker related TR, left heart disease related TR, congenital heart related TR, right ventricular (RV) myopathy, pulmonary hypertension and, finally idiopathic TR step by step.

Results

There were 29 (14%) primary TR, 18 (8.7%) pacemaker related, 81 (39.1 %) left heart diseases, 6 (2.9%) congenital heart diseases, 3 (1.4%) RV myopathy, 27 (13%) pulmonary hypertension, and 43 (20.8%) idiopathic TR. Mean age of idiopathic TR was 72.9 ± 11.4 years and 39.5% was male which were not different from other groups. Atrial fibrillation was presented highest in patients with pacemaker related TR (77.8%) and left heart disease (55.6%), lowest in primary TR (24.1%) and pulmonary HT (25.9%), and modest in idiopathic TR (44.2%). Among the echocardiographic characteristics of right heart measurements, idiopathic TR had lowest TR maximal velocity (3.0 ± 0.3 m/s), pulmonary (41.2 ± 8.7 mmHg) and right atrium pressure (5.3 ± 0.3 mmHg; all p <0.001). Idiopathic TR had smallest RV wall thickness (4.5 ± 1.4 mm; p = 0.008), tricuspid annulus diameter (3.2 ± 0.7 cm; p = 0.001), and right atrial area (18.9 ± 8.4 cm2; p <0.001). RV function represented as tricuspid annulus velocity S’ (12.8 ± 3.3 cm/s; p = 0.011) and RV fractional area change FAC (42.6 ± 16.0 %; p <0.001) were best in idiopathic TR. RV dysfunction (FAC < 35%) was lowest (14%) in idiopathic TR.

Conclusions

Idiopathic TR had better RV function then other types of TR. Idiopathic TR can be regarded as a unique disease category in studying TR.

Constraints on Lorentz Invariance Violation from HAWC Observations of Gamma Rays above 100 TeV

Because of the high energies and long distances to the sources, astrophysical observations provide a unique opportunity to test possible signatures of Lorentz invariance violation (LIV). Superluminal LIV enables the decay of photons at high energy. The high altitude water Cherenkov (HAWC) observatory is among the most sensitive gamma-ray instruments currently operating above 10 TeV. HAWC finds evidence of 100 TeV photon emission from at least four astrophysical sources. These observations exclude, for the strongest of the limits set, the LIV energy scale to 2.2×10^{31}  eV, over 1800 times the Planck energy and an improvement of 1 to 2 orders of magnitude over previous limits.

Multiple Galactic Sources with Emission Above 56 TeV Detected by HAWC

We present the first catalog of gamma-ray sources emitting above 56 and 100 TeV with data from the High Altitude Water Cherenkov Observatory, a wide field-of-view observatory capable of detecting gamma rays up to a few hundred TeV. Nine sources are observed above 56 TeV, all of which are likely galactic in origin. Three sources continue emitting past 100 TeV, making this the highest-energy gamma-ray source catalog to date. We report the integral flux of each of these objects. We also report spectra for three highest-energy sources and discuss the possibility that they are PeVatrons.

P1771 Gender differences of the blood pressure effects on early changes of left ventricle mechanics in untreated hypertension

Background

Left ventricular (LV) diastolic dyssynchrony and global and layer-specific strain can be used for evaluation of early myocardial changes in hypertension. We tried to investigate the gender differences in these early changes in untreated uncomplicated hypertension.

Methods

This study included 43 consecutive patients (mean age 51.3 ±12.5 years, 56% men) with newly diagnosed hypertension from an out-patient clinic. All subjects were free of complications including renal dysfunction, LV hypertrophy, and diabetes. Comprehensive transthoracic echocardiography (E9, GE, USA) was conducted before treatment of hypertension. Diastolic and systolic parameters were measured by two-dimension (2D), Doppler, tissue Doppler imaging and 2D speckle tracking echocardiography (STE). The time-to-peak early diastolic myocardial annulus velocity (Te) at 6 LV segments from apical-4-chamber, apical-2-chamber and apical-3-chamber views were measured with reference to the QRS complex. The time to peak early diastolic strain rate (TDSr), global longitudinal strain (GLS), layer-specific longitudinal strain included sub-epicardial strain (EpiLS) and sub-endocardial strain (EndLS) were measured from 18 LV segments by STE. Diastolic dyssynchrony parameters were defined as the standard deviation (SD) of Te of all LV segments (Te-SD), SD of TDSr of 18 LV segments (TDSr-SD), and the maximal difference between any two TDSr of the 18 LV segments (MaxD-TDSr).

Results

There were no differences between men (56%) and women (44%) regarding age, initial blood pressure, hypertension duration, LV mass index, LV ejection fraction, and early mitral velocity to average early annulus velocity ratio. Regarding diastolic dyssynchrony parameters, men were significantly higher than women including Te-SD (22.3 ± 13.8 vs. 14.7 ± 4.2 ms; p = 0.016), TDSrSD (46.0 ± 13.3 vs. 35.3 ± 11.4 ±ms; p = 0.008), and MaxD-TDSr (162.0 ± 40.3 vs. 128.1 ± 50.7 ms; p = 0.019). Men also had worse GLS (-17.6 ± 1.9 vs. -19.5 ± 2.5 %; p = 0.007), EpiLS (-15.1 ± 1.7 vs. -17.0 ± 2.3, p = 0.003), and EndLS (-20.5 ± 2.2 vs. -22.4 ± 2.8 %; p = 0.018) than women. After multivariate analysis controlling age, systolic blood pressure, and LV mass index, TeSD (p = 0.039), TDSrSD (p = 0.018), MaxD-TDSr (p = 0.035) were still significantly higher than women. GLS (p = 0.046), and EpiLS (p = 0.025) were still worse in men.

Conclusion

In the same age, blood pressure, hypertension duration and LV mass index, men have more diastolic dyssynchrony and worse myocardial strain in untreated hypertension.

An extra copy of the β-glucosidase gene improved the cellobiose fermentation capability of an engineered Saccharomyces cerevisiae strain

In a previously engineered Saccharomyces cerevisiae recombinant, the cellobiose fermentation rate was significantly lower than the glucose fermentation rate. Thus, we implemented a genome-wide perturbation library to find gene targets for improving the cellobiose fermentation capability of the yeast strain. Unexpectedly, we discovered a transformant that contained an additional β-glucosidase gene (gh1-1), possibly through homologous recombination between the plasmids. The additional β-glucosidase led to the fastest cellobiose fermentation activity among all the transformants evaluated, and the strain demonstrated significantly higher β-glucosidase activity than the control strain, especially during the initial exponential growth phase. The present work revealed the benefit of the extra gh1-1 copy for efficient cellobiose fermentation in the engineered S. cerevisiae strain.

Publisher Correction: Very-high-energy particle acceleration powered by the jets of the microquasar SS 433

In this Letter, owing to a production error, the penultimate version of the PDF was published. The HTML version was always correct. The PDF has been corrected online.

Preservation of fruit and vegetable discards with sodium metabisulfite

Two series of experiments were performed to investigate the aerobic preservation of fruit and vegetable discards (FVD) using sodium metabisulfite (SMB). In Exp. 1, metabisulfite was applied at 0, 2, 4, 6, and 8 g/kg FVD for 0, 3, 6, 9, and 12 d. Metabisulfite treatment at 6 and 8 g/kg FVD was highly effective in controlling putrefaction and preserving the nutrient components for 6 and 9 d, respectively. In the pilot-scale experiment (Exp. 2), SMB was applied at 0 and 8 g/kg FVD in a 600-L bucket for 0, 6, and 9 d in an outdoor environment. The SMB treatment was highly effective in maintaining the integrity and freshness of FVD, suppressing microbial proliferation, and preserving the nutrient constituents. Under the conditions of this study, SMB effectively preserved FVD in an aerobic environment, enabling their more efficient long-term recycling through livestock feed or development of value-added products.

Extended gamma-ray sources around pulsars constrain the origin of the positron flux at Earth

The unexpectedly high flux of cosmic-ray positrons detected at Earth may originate from nearby astrophysical sources, dark matter, or unknown processes of cosmic-ray secondary production. We report the detection, using the High-Altitude Water Cherenkov Observatory (HAWC), of extended tera-electron volt gamma-ray emission coincident with the locations of two nearby middle-aged pulsars (Geminga and PSR B0656+14). The HAWC observations demonstrate that these pulsars are indeed local sources of accelerated leptons, but the measured tera-electron volt emission profile constrains the diffusion of particles away from these sources to be much slower than previously assumed. We demonstrate that the leptons emitted by these objects are therefore unlikely to be the origin of the excess positrons, which may have a more exotic origin.

Cortical abnormalities in bipolar disorder: an MRI analysis of 6503 individuals from the ENIGMA Bipolar Disorder Working Group

Despite decades of research, the pathophysiology of bipolar disorder (BD) is still not well understood. Structural brain differences have been associated with BD, but results from neuroimaging studies have been inconsistent. To address this, we performed the largest study to date of cortical gray matter thickness and surface area measures from brain magnetic resonance imaging scans of 6503 individuals including 1837 unrelated adults with BD and 2582 unrelated healthy controls for group differences while also examining the effects of commonly prescribed medications, age of illness onset, history of psychosis, mood state, age and sex differences on cortical regions. In BD, cortical gray matter was thinner in frontal, temporal and parietal regions of both brain hemispheres. BD had the strongest effects on left pars opercularis (Cohen's d=-0.293; P=1.71 × 10^-21), left fusiform gyrus (d=-0.288; P=8.25 × 10^-21) and left rostral middle frontal cortex (d=-0.276; P=2.99 × 10^-19). Longer duration of illness (after accounting for age at the time of scanning) was associated with reduced cortical thickness in frontal, medial parietal and occipital regions. We found that several commonly prescribed medications, including lithium, antiepileptic and antipsychotic treatment showed significant associations with cortical thickness and surface area, even after accounting for patients who received multiple medications. We found evidence of reduced cortical surface area associated with a history of psychosis but no associations with mood state at the time of scanning. Our analysis revealed previously undetected associations and provides an extensive analysis of potential confounding variables in neuroimaging studies of BD.

Effective acute care handover to GP: optimising the structure to improve discharge documentation

Time and resource constraints have often led to the use of assessment records as discharge communications from acute and emergency departments. However, whether this addresses the primary care needs has not been demonstrated. This study examined the optimal structure that can impart key discharge information effectively using feedback from general practitioners (GP). We implemented an electronic assessment template that focused on the most relevant headings. Prespecified process measures were examined and qualitative thematic analysis of free-text comments from GP surveys were conducted to optimise the document. Our findings suggest that the structure of a discharge summary can influence the quality of information, users' compliance and readers' perceptions of the length of the letter.

Dynamic Internet-Mediated Team-Based Case Management of High-Frequency Emergency Department Users

Introduction

We assessed whether a strategy using dynamic, internet-mediated, team-based case management could reduce the number of subsequent emergency department (ED) visits by frequent ED users.

Methods

Patients who attended the ED three or more times within 72 hours in June 2010 were identified. These cases were divided into the pain management or chronic disease group according to their chief complaint. Patients were assessed by expert panels, and initial care plans were developed and posted on an internal website. Thereafter, each emergency physician could follow or adjust the care plans dynamically via the internal website according to the patient's condition and use the website to communicate results. Care plans were revised by the team according to the patient's clinical situation as it changed. Patient ED visits over the subsequent six months were monitored.

Results

Fourteen cases were enrolled in the study, seven in each group. The mean number of visits per patient per month in the pain management and chronic disease groups decreased from 14.9 to 5.79 (p=0.031) and 6.1 to 2.9 (p<0.001) visits per month after the intervention, respectively. The overall mean number of visits per patient per month decreased from 10.5 to 4.36 (p=0.004), a decrease of 6.14 visits (58.27%).

Conclusions

Dynamic internet-mediated team-based case management may help to reduce subsequent visits in patients who frequently visit the ED. (Hong Kong j.emerg.med. 2014;21:161-166)

Neural correlates of affective and non-affective cognition in obsessive compulsive disorder: A meta-analysis of functional imaging studies

Obsessive compulsive disorder (OCD) is characterized by intrusive thoughts and repetitive ritualistic behaviors and has been associated with diverse functional brain abnormalities. We sought to synthesize current evidence from functional magnetic resonance imaging (fMRI) studies and examine their alignment to pathogenetic models of OCD. Following systematic review, we identified 54 task-fMRI studies published in the last decade comparing adults with OCD (n=1186) to healthy adults (n=1159) using tasks of affective and non-affective cognition. We used voxel-based quantitative meta-analytic methods to combine primary data on anatomical coordinates of case-control differences, separately for affective and non-affective tasks. We found that functional abnormalities in OCD cluster within cortico-striatal thalamic circuits. Within these circuits, the abnormalities identified showed significant dependence on the affective or non-affective nature of the tasks employed as circuit probes. In studies using affective tasks, patients overactivated regions involved in salience, arousal and habitual responding (anterior cingulate cortex, insula, caudate head and putamen) and underactivated regions implicated in cognitive and behavioral control (medial prefrontal cortex, posterior caudate). In studies using non-affective cognitive tasks, patients overactivated regions involved in self-referential processing (precuneus, posterior cingulate cortex) and underactivated subcortical regions that support goal-directed cognition and motor control (pallidum, ventral anterior thalamus, posterior caudate). The overall pattern suggests that OCD-related brain dysfunction involves increased affective and self-referential processing, enhanced habitual responding and blunted cognitive control.

Arterial Embolism Occurring During Percutaneous Thrombectomy of Dialysis Graft

PURPOSE

To evaluate the incidence, management methods and follow-up results of arterial embolism during percutaneous thrombectomy of hemodialysis grafts.

MATERIALS AND METHODS

After Institutional Review Board approval, the radiologic database of our department for percutaneous thrombectomy procedure in hemodialysis access was retrospectively reviewed. Between 1998 and June 2014, 2975 percutaneous thrombectomy procedures using thromboaspiration technique were performed in 1524 patients with thrombosed hemodialysis grafts. After thrombectomy, angioplasty was performed for significant stenoses. The incidence of arterial embolism was analyzed according to the location/shape of the arteriovenous graft. Percutaneous management methods of arterial embolism and long-term follow-up results by fistulography were also evaluated.

RESULTS

Arterial embolism was documented by angiography in 117 cases (3.9%). Of these, three were symptomatic and subsided after embolectomy. The incidence was significantly correlated with the location/shape of the graft (p = 0.001). Arterial emboli were retrieved using occlusion balloon/Fogarty balloon (n = 58), guiding catheter-assisted aspiration (n = 36), sheath-assisted aspiration (n = 2) and back-bleeding technique (n = 3). Others were observed without intervention (n = 17) or surgically removed (n = 1). Arterial emboli were completely retrieved in 86 cases and partially retrieved in 13 cases. Ulnar artery rupture occurred in one case due to over-inflation of the occlusion balloon. Follow-up fistulography performed in 60 patients among whom 99 percutaneous embolectomies were done revealed arterial stenosis/occlusion in 7 and residual emboli in one patient. In observed patients without intervention, follow-up documented complete resolution of the emboli without arterial stenosis in 9 patients.

CONCLUSION

Radiologically perceivable arterial embolism is uncommon during percutaneous thrombectomy of thrombosed dialysis grafts. The majority of the emboli can be retrieved by percutaneous techniques, but may induce arterial damage in some patients. Clinical observation can be another option for patients without ischemic symptoms.

Amelioration of the Behavioral Phenotype in Genetically Ataxic Mice through Bilateral Intracerebellar Grafting of Fetal Purkinje Cells

We have previously applied neural grafting to “Purkinje cell degeneration” mutant mice (gene symbol pcd, mouse chromosome 13), a model of recessively inherited cerebello-olivary atrophy, to create appropriate interactions between wild-type and mutant cells in elucidating gene effects on the involved neuron populations and to address issues of the structural integration of donor Purkinje cells into the disrupted cerebellar loop. Behaviorally, pcd homozygotes manifest ataxic signs beginning at 3-4 wk of age. The functional effects of cerebellar transplants on motor performance have long remained an open question. The aim of the present study was to determine the recovery of motor responses in pcd mutants in a battery of behavioral tasks after bilateral transplantation of cerebellar cell suspensions (prepared from wild-type mice) into the parenchyma of the deep cerebellar nuclei of the hosts, according to a protocol that emphasizes the reconstruction of the missing inhibitory cortico-nuclear projection. With this approach, the denervated deep nuclei of the host receive a new Purkinje axonal innervation; further, most transplanted Purkinje cells end up occupying cortical localities anyway and display a correct dendritic tree orientation toward the pia. Motor coordination and fatigue resistance were assessed in a rotarod treadmill apparatus, a behavioral paradigm useful in studying various brain abiotrophies and treatments, including developmental perturbations of the cerebellar cytoarchitecture. Locomotor activity was quantified by the number of squares mice crossed as they moved about in an open-field matrix. Grafted pcd mice performed significantly better than sham-operated mutants in both of these tasks. Moreover, graft-recipient mice were able to sustain their abdomen above the floor on their limbs during movement, contrasting to the typical lowered, widened stance of sham-operated pcd mutants. These findings clearly demonstrate that bilateral transplants of fetal Purkinje cells have functional effects on motor performance in the pcd model of hereditary cerebellar ataxia.