[Clinical efficacy of intraarticular vancomycin in preventing early periprosthetic joint infection after primary knee arthroplasty]

Objective: To investigate the clinical effect of intraarticular vancomycin on early periprosthetic joint infection (PJI) in knee arthroplasty and the incidence of postoperative complications. Methods: This is a retrospective cohort study. The clinical data of 1 867 patients who underwent primary knee arthroplasty at Department of Joint Surgery, the Affiliated Hospital of Qingdao University from April 2022 to June 2023 were retrospectively analysed, including total knee arthroplasty (TKA), robotic-assisted total knee arthroplasty (RA-TKA) and unicondylar knee arthroplasty (UKA). There were 687 males and 1180 females, aged (68.0±11.2)years(range:45 to 87 years). Patients were divided into the vancomycin group and the control group according to whether or not intra-articular injection of 1 g of vancomycin powder dissolved in 30 ml of saline was performed after intraoperative joint capsule closure. In the vancomycin group, 925 patients were included, including 782 TKA, 27 RA-TKA and 116 UKA.In the control group, 942 patients were included, including 767 TKA, 99 RA-TKA and 76 UKA. Early PJI, wound complications, and vancomycin-related toxicity including acute renal collapse, ototoxicity, and allergic reactions were assessed within 3 months postoperatively. Results: No PJI was found in all patients in the vancomycin group.Five cases (0.7%,5/767) of early PJI were found in TKA patients in the control group, with a statistically significant difference (P=0.030); 1 case of early PJI was found in each RA-TKA and UKA patients, with non-significant difference compared with vancomycin group (all P>0.05). Two cases (0.3%,2/782) of incisional complications were found in TKA patients in the vancomycin group, and 4 cases (0.5%, 4/767) of incisional complications were found in TKA patients in the control group, with non-significant difference(P=0.449); no incisional complications were found in RA-TKA patients in the vancomycin group, and 1 case (1.0%,1/99) of incisional complications were found in RA-TKA patients in the control group, the difference was not statistically significant (P>0.05); no incisional complications were found in both groups of UKA patients.No vancomycin-related acute kidney injury, ototoxicity, or allergic reactions was observed in all patients. Conclusion: Intra-articular injection of 1 g of vancomycin suspension after arthrotomy closure during TKA maybe lower the risk of early PJI without increasing the risk of wound complication and vancomycin-associated systemic toxicity.

A neural signature for the subjective experience of threat anticipation under uncertainty

Uncertainty about potential future threats and the associated anxious anticipation represents a key feature of anxiety. However, the neural systems that underlie the subjective experience of threat anticipation under uncertainty remain unclear. Combining an uncertainty-variation threat anticipation paradigm that allows precise modulation of the level of momentary anxious arousal during functional magnetic resonance imaging (fMRI) with multivariate predictive modeling, we train a brain model that accurately predicts subjective anxious arousal intensity during anticipation and test it across 9 samples (total n = 572, both gender). Using publicly available datasets, we demonstrate that the whole-brain signature specifically predicts anxious anticipation and is not sensitive in predicting pain, general anticipation or unspecific emotional and autonomic arousal. The signature is also functionally and spatially distinguishable from representations of subjective fear or negative affect. We develop a sensitive, generalizable, and specific neuroimaging marker for the subjective experience of uncertain threat anticipation that can facilitate model development.

Irritable Bowel Syndrome Is Associated With Brain Health by Neuroimaging, Behavioral, Biochemical, and Genetic Analyses

BACKGROUND

Irritable bowel syndrome (IBS) interacts with psychopathology in a complex way; however, little is known about the underlying brain, biochemical, and genetic mechanisms.

METHODS

To clarify the phenotypic and genetic associations between IBS and brain health, we performed a comprehensive retrospective cohort study on a large population. Our study included 171,104 participants from the UK Biobank who underwent a thorough assessment of IBS, with the majority also providing neuroimaging, behavioral, biochemical, and genetic information. Multistage linked analyses were conducted, including phenome-wide association analysis, polygenic risk score calculation, and 2-sample Mendelian randomization analysis.

RESULTS

The phenome-wide association analysis showed that IBS was linked to brain health problems, including anxiety and depression, and poor cognitive performance. Significantly lower brain volumes associated with more severe IBS were found in key areas related to emotional regulation and higher-order cognition, including the medial orbitofrontal cortex/ventromedial prefrontal cortex, anterior insula, anterior and mid-cingulate cortices, dorsolateral prefrontal cortex, and hippocampus. Higher triglycerides, lower high-intensity lipoprotein, and lower platelets were also related (p < 1 × 10-10) to more severe IBS. Finally, Mendelian randomization analyses demonstrated potential causal relationships between IBS and brain health and indicated possible mediating effects of dyslipidemia and inflammation.

CONCLUSIONS

For the first time, this study provides a comprehensive understanding of the relationship between IBS and brain health phenotypes, integrating perspectives from neuroimaging, behavioral performance, biochemical factors, and genetics, which is of great significance for clinical applications to potentially address brain health impairments in patients with IBS.

Fractionation of neural reward processing into independent components by novel decoding principle

How to retrieve latent neurobehavioural processes from complex neurobiological signals is an important yet unresolved challenge. Here, we develop a novel approach, orthogonal-Decoding multi-Cognitive Processes (DeCoP), to reveal underlying latent neurobehavioural processing and show that its performance is superior to traditional non-orthogonal decoding in terms of both false inference and robustness. Processing value and salience information are two fundamental but mutually confounded pathways of reward reinforcement essential for decision making. During reward/punishment anticipation, we applied DeCoP to decode brain-wide responses into spatially overlapping, yet functionally independent, evaluation and readiness processes, which are modulated differentially by meso‑limbic vs nigro-striatal dopamine systems. Using DeCoP, we further demonstrated that most brain regions only encoded abstract information but not the exact input, except for dorsal anterior cingulate cortex and insula. Furthermore, we anticipate our novel analytical principle to be applied generally in decoding multiple latent neurobehavioral processes and thus advance both the design and hypothesis testing for cognitive tasks.

Two neurostructural subtypes: results of machine learning on brain images from 4,291 individuals with schizophrenia

Machine learning can be used to define subtypes of psychiatric conditions based on shared clinical and biological foundations, presenting a crucial step toward establishing biologically based subtypes of mental disorders. With the goal of identifying subtypes of disease progression in schizophrenia, here we analyzed cross-sectional brain structural magnetic resonance imaging (MRI) data from 4,291 individuals with schizophrenia (1,709 females, age=32.5 years±11.9) and 7,078 healthy controls (3,461 females, age=33.0 years±12.7) pooled across 41 international cohorts from the ENIGMA Schizophrenia Working Group, non-ENIGMA cohorts and public datasets. Using a machine learning approach known as Subtype and Stage Inference (SuStaIn), we implemented a brain imaging-driven classification that identifies two distinct neurostructural subgroups by mapping the spatial and temporal trajectory of gray matter (GM) loss in schizophrenia. Subgroup 1 (n=2,622) was characterized by an early cortical-predominant loss (ECL) with enlarged striatum, whereas subgroup 2 (n=1,600) displayed an early subcortical-predominant loss (ESL) in the hippocampus, amygdala, thalamus, brain stem and striatum. These reconstructed trajectories suggest that the GM volume reduction originates in the Broca's area/adjacent fronto-insular cortex for ECL and in the hippocampus/adjacent medial temporal structures for ESL. With longer disease duration, the ECL subtype exhibited a gradual worsening of negative symptoms and depression/anxiety, and less of a decline in positive symptoms. We confirmed the reproducibility of these imaging-based subtypes across various sample sites, independent of macroeconomic and ethnic factors that differed across these geographic locations, which include Europe, North America and East Asia. These findings underscore the presence of distinct pathobiological foundations underlying schizophrenia. This new imaging-based taxonomy holds the potential to identify a more homogeneous sub-population of individuals with shared neurobiological attributes, thereby suggesting the viability of redefining existing disorder constructs based on biological factors.

Structural neurodevelopment at the individual level - a life-course investigation using ABCD, IMAGEN and UK Biobank data

Adolescents exhibit remarkable heterogeneity in the structural architecture of brain development. However, due to the lack of large-scale longitudinal neuroimaging studies, existing research has largely focused on population averages and the neurobiological basis underlying individual heterogeneity remains poorly understood. Using structural magnetic resonance imaging from the IMAGEN cohort (n=1,543), we show that adolescents can be clustered into three groups defined by distinct developmental patterns of whole-brain gray matter volume (GMV). Genetic and epigenetic determinants of group clustering and long-term impacts of neurodevelopment in mid-to-late adulthood were investigated using data from the ABCD, IMAGEN and UK Biobank cohorts. Group 1, characterized by continuously decreasing GMV, showed generally the best neurocognitive performances during adolescence. Compared to Group 1, Group 2 exhibited a slower rate of GMV decrease and worsened neurocognitive development, which was associated with epigenetic changes and greater environmental burden. Further, Group 3 showed increasing GMV and delayed neurocognitive development during adolescence due to a genetic variation, while these disadvantages were attenuated in mid-to-late adulthood. In summary, our study revealed novel clusters of adolescent structural neurodevelopment and suggested that genetically-predicted delayed neurodevelopment has limited long-term effects on mental well-being and socio-economic outcomes later in life. Our results could inform future research on policy interventions aimed at reducing the financial and emotional burden of mental illness.

[Radiomics-based prediction of microsatellite instability in stage Ⅱ and Ⅲ rectal cancer patients based on T2WI MRI and diffusion-weighted imaging]

Objective: To examine the radiomics model based on high-resolution T2WI and diffusion weighted imaging (DWI) in predicting microsatellite stability in patients with stage Ⅱ and Ⅲ rectal cancer. Methods: From February 2016 to October 2020, 175 patients with stage Ⅱ and Ⅲ rectal cancer who met the inclusion criteria were retrospectively collected. There were 119 males and 56 females, aged (63.9±9.4) years (range: 37 to 85 years), including 152 patients with microsatellite stability and 23 patients with microsatellite instability. All patients were randomly divided into the training group (n=123) and the validation group (n=52) with a ratio of 7∶3. The region of interest was labeled on the T2WI and DWI images of each patient using the ITK-SNAP software, and PyRadiomics was used to extract seven kinds of radiomics features. After removing redundant features and normalizing features, the least absolute shrinkage and selection operation were used for feature selection. One clinical model, three radiomics models and one clinical-radiomics model were constructed in the training group based on a support vector machine. The area under receiver operating characteristic curve (AUC), sensitivity, specificity, and accuracy were used to evaluate the performance of the models in the verification group. Results: Three clinical features (age, degree of tumor differentiation, and distance from the lower edge of the tumor to the anal edge) and six radiomics features (two DWI-related features and four T2WI-related features) most related to microsatellite status of rectal cancer patients were selected. The AUC of the clinical-radiomics model in the training group was 0.95. In the validation group, the AUC was 0.81, better than the clinical model (0.68, Z=0.71, P=0.04), and equivalent to the T2WI+DWI model (0.82, Z=0.21, P=0.83). Conclusions: Radiomic features based on preoperative T2WI and DWI were related to microsatellite stability in patients with stage Ⅱ and Ⅲ rectal cancer and showed a high classification efficiency. The model based on the features provided a noninvasive and convenient tool for preoperative determination of microsatellite stability in rectal cancer patients.

Spectrally efficient multi-service fiber-wireless access in low-cost direct-detection THz system at 300 GHz

This Letter demonstrates a novel, to the best of knowledge, overlapping single-sideband (OSSB) transmission scheme for spectrally efficient multi-service fiber-wireless (FiWi) access in a low-cost direct-detection (DD) THz system. Utilizing the proposed OSSB scheme, user data from different services can share the same spectrum resource yet can be successfully demodulated via one cost-effective DD THz receiver in conjunction with the Kramers-Kronig (KK) based SSB field reconstruction and look-up table (LUT) enabled signal separation algorithms. A proof-of-principle experiment is conducted. Based on an IQ modulator and a single THz zero-bias diode (ZBD), two independent 10-GBd quadrature phase shift keying (QPSK) signals with an overlapped spectrum are successfully demodulated after 20-km fiber and up to 3-m wireless transmission at the 300-GHz band. To the best of our knowledge, this is the first demonstration of multi-service FiWi access with an OSSB format in a 300-GHz DD THz system.

Association between vmPFC gray matter volume and smoking initiation in adolescents

Smoking of cigarettes among young adolescents is a pressing public health issue. However, the neural mechanisms underlying smoking initiation and sustenance during adolescence, especially the potential causal interactions between altered brain development and smoking behaviour, remain elusive. Here, using large longitudinal adolescence imaging genetic cohorts, we identify associations between left ventromedial prefrontal cortex (vmPFC) gray matter volume (GMV) and subsequent self-reported smoking initiation, and between right vmPFC GMV and the maintenance of smoking behaviour. Rule-breaking behaviour mediates the association between smaller left vmPFC GMV and smoking behaviour based on longitudinal cross-lagged analysis and Mendelian randomisation. In contrast, smoking behaviour associated longitudinal covariation of right vmPFC GMV and sensation seeking (especially hedonic experience) highlights a potential reward-based mechanism for sustaining addictive behaviour. Taken together, our findings reveal vmPFC GMV as a possible biomarker for the early stages of nicotine addiction, with implications for its prevention and treatment.

Brain and molecular mechanisms underlying the nonlinear association between close friendships, mental health, and cognition in children

Close friendships are important for mental health and cognition in late childhood. However, whether the more close friends the better, and the underlying neurobiological mechanisms are unknown. Using the Adolescent Brain Cognitive Developmental study, we identified nonlinear associations between the number of close friends, mental health, cognition, and brain structure. Although few close friends were associated with poor mental health, low cognitive functions, and small areas of the social brain (e.g., the orbitofrontal cortex, the anterior cingulate cortex, the anterior insula, and the temporoparietal junction), increasing the number of close friends beyond a level (around 5) was no longer associated with better mental health and larger cortical areas, and was even related to lower cognition. In children having no more than five close friends, the cortical areas related to the number of close friends revealed correlations with the density of μ-opioid receptors and the expression of OPRM1 and OPRK1 genes, and could partly mediate the association between the number of close friends, attention-deficit/hyperactivity disorder (ADHD) symptoms, and crystalized intelligence. Longitudinal analyses showed that both too few and too many close friends at baseline were associated with more ADHD symptoms and lower crystalized intelligence 2 y later. Additionally, we found that friendship network size was nonlinearly associated with well-being and academic performance in an independent social network dataset of middle-school students. These findings challenge the traditional idea of 'the more, the better,' and provide insights into potential brain and molecular mechanisms.

A shared neural basis underlying psychiatric comorbidity

Recent studies proposed a general psychopathology factor underlying common comorbidities among psychiatric disorders. However, its neurobiological mechanisms and generalizability remain elusive. In this study, we used a large longitudinal neuroimaging cohort from adolescence to young adulthood (IMAGEN) to define a neuropsychopathological (NP) factor across externalizing and internalizing symptoms using multitask connectomes. We demonstrate that this NP factor might represent a unified, genetically determined, delayed development of the prefrontal cortex that further leads to poor executive function. We also show this NP factor to be reproducible in multiple developmental periods, from preadolescence to early adulthood, and generalizable to the resting-state connectome and clinical samples (the ADHD-200 Sample and the Stratify Project). In conclusion, we identify a reproducible and general neural basis underlying symptoms of multiple mental health disorders, bridging multidimensional evidence from behavioral, neuroimaging and genetic substrates. These findings may help to develop new therapeutic interventions for psychiatric comorbidities.

Real-time 100-GbE fiber-wireless seamless integration system using an electromagnetic dual-polarized single-input single-output wireless link at the W band

This Letter demonstrates a real-time 100-GbE fiber-wireless seamless integration system operating at the whole W band (75-110 GHz). Based on a pair of commercial digital coherent optical modules, the real-time transparent transmission of 125-Gb/s dual-polarized quadrature phase-shift keying signal has been successfully achieved over two-spans of 20-km fiber and up to 150-m electromagnetic dual-polarized single-input single-output wireless link. To the best of our knowledge, this is the first real-time demonstration of 100-GbE signal transmission over >100-m wireless distance at the millimeter-wave band based on photonics. We believed this real-time and high-speed fiber-wireless seamless integration system with a wireless coverage up to hundreds of meters can significantly accelerate the progress of upcoming 6G.

Increased Dietary Niacin Intake Improves Muscle Strength, Quality, and Glucose Homeostasis in Adults over 40 Years of Age

BACKGROUND AND AIMS

Age-related loss of skeletal muscle mass and strength begins at 40 years of age, and limited evidence suggests that niacin supplementation increases levels of nicotinamide adenine dinucleotide in mouse muscle tissue. In addition, skeletal muscle has a key role in the body's processing of glucose. Therefore, this study aimed to investigate the relationship between dietary niacin and skeletal muscle mass, strength, and glucose homeostasis in people aged 40 years and older.

METHODS

This study was an American population-based cross-sectional analysis using data from the National Health and Nutrition Examination Survey (NHANES). Considering that some outcomes are only measured in specific survey cycles and subsamples, we established three data sets: a grip strength dataset (2011-2014, n=3772), a body mass components dataset (2011-2018, n=3279), and a glucose homeostasis dataset (1999-2018, n=9189). Dietary niacin and covariates were measured in all survey cycles. Linear regression or logistic regression models that adjusted for several main covariates, such as physical activity and diet, was used to evaluate the relationship between dietary niacin and grip strength, total lean mass, appendicular lean mass, total fat, trunk fat, total bone mineral content, homeostasis model assessment of insulin resistance (HOMA-IR), fasting blood glycose, fasting insulin and sarcopenia risk. Subgroup analyses, a trend test, an interaction test, and a restricted cubic spline were used for further exploration.

RESULTS

Higher dietary niacin intake was significantly correlated with higher grip strength (β 0.275, 95% confidence intervals [CI] 0.192-0.357), higher total lean mass (β 0.060, 95% CI 0.045-0.074), higher appendicular lean mass (β 0.025, 95% CI 0.018-0.033), and higher total bone mineral content (β 0.005, 95% CI 0.004-0.007). By contrast, higher dietary niacin intake was significantly associated with lower total fat (β -0.061, 95% CI -0.076 to -0.046), lower trunk fat (β -0.041, 95% CI -0.050 to -0.032) and lower sarcopenia risk (OR 0.460, 95% CI 0.233 to 0.907). In addition, dietary niacin significantly reduced HOMA-IR, fasting blood glucose (in participants without diabetes), and fasting insulin (p <0.05).

CONCLUSION

Niacin is associated with improved body composition (characterized by increased muscle mass and decreased fat content) and improved glucose homeostasis in dietary doses. Dietary niacin supplementation is a feasible way to alleviate age-related muscular loss.

Late-Night Overeating and All-Cause and Cardiovascular Disease Mortality in Adults Aged ≥ 50: A Cohort Study

BACKGROUND

Late-night overeating (LNOE) is closely associated with many health risk factors, but whether LNOE can increase the risk of death remains unknown. Thus, the prospective cohort study aimed to investigate the relationship between LNOE and mortality using data from the National Health and Nutrition Examination Survey.

METHODS

11,893 participants aged 50 years and older were included in the study. Dietary information was obtained through 24-h dietary recall interviews. Cox regression, subgroup, sensitivity, and restricted cubic spline analyses were used to assess the association between LNOE and mortality.

RESULTS

During a median follow-up of 8.3 years, 2,498 deaths occurred. After adjusting for major confounders, compared to the non-late-night eating (NLNE) group, the LNOE group was associated with higher risks of all-cause (HR = 1.47, 95% CI = 1.06-2.04) and cardiovascular disease (CVD) mortality (HR = 2.02, 95% CI = 1.13-3.60). No significant association was found between late-night eating (LNE) and mortality. Subgroup analyses showed that the LNOE group had a greater risk of all-cause and CVD mortality in participants older than 70 years, with alcohol consumption and hypertension and demonstrated an increased risk of all-cause mortality in males and higher CVD mortality in females.

CONCLUSION

The habit of LNOE was an independent risk factor for all-cause and CVD mortality in US adults aged 50 years and older, which was also influenced by age, sex, alcohol consumption, and hypertension.

Language abnormalities in schizophrenia: binding core symptoms through contemporary empirical evidence

Both the ability to speak and to infer complex linguistic messages from sounds have been claimed as uniquely human phenomena. In schizophrenia, formal thought disorder (FTD) and auditory verbal hallucinations (AVHs) are manifestations respectively relating to concrete disruptions of those abilities. From an evolutionary perspective, Crow (1997) proposed that "schizophrenia is the price that Homo sapiens pays for the faculty of language". Epidemiological and experimental evidence points to an overlap between FTD and AVHs, yet a thorough investigation examining their shared neural mechanism in schizophrenia is lacking. In this review, we synthesize observations from three key domains. First, neuroanatomical evidence indicates substantial shared abnormalities in language-processing regions between FTD and AVHs, even in the early phases of schizophrenia. Second, neurochemical studies point to a glutamate-related dysfunction in these language-processing brain regions, contributing to verbal production deficits. Third, genetic findings further show how genes that overlap between schizophrenia and language disorders influence neurodevelopment and neurotransmission. We argue that these observations converge into the possibility that a glutamatergic dysfunction in language-processing brain regions might be a shared neural basis of both FTD and AVHs. Investigations of language pathology in schizophrenia could facilitate the development of diagnostic tools and treatments, so we call for multilevel confirmatory analyses focused on modulations of the language network as a therapeutic goal in schizophrenia.

Lower gestational age is associated with lower cortical volume and cognitive and educational performance in adolescence

BACKGROUND

Gestational age (GA) is associated with later cognition and behavior. However, it is unclear how specific cognitive domains and brain structural development varies with the stepwise change of gestational duration.

METHODS

This large-scale longitudinal cohort study analyzed 11,878 early adolescents' brain volume maps at 9-10 years (baseline) and 5685 at 11-12 years (a 2-year follow-up) from the Adolescent Brain Cognitive Development (ABCD) study. According to gestational age, adolescents were divided into five categorical groups: ≤ 33 weeks, 34-35 weeks, 36 weeks, 37-39 weeks, and ≥ 40 weeks. The NIH Toolbox was used to estimate neurocognitive performance, including crystallized and fluid intelligence, which was measured for 11,878 adolescents at baseline with crystallized intelligence and relevant subscales obtained at 2-year follow-up (with participant numbers ranging from 6185 to 6310 depending on the cognitive domain). An additional large population-based cohort of 618,070 middle adolescents at ninth-grade (15-16 years) from the Danish national register was utilized to validate the association between gestational age and academic achievements. A linear mixed model was used to examine the group differences between gestational age and neurocognitive performance, school achievements, and grey matter volume. A mediation analysis was performed to examine whether brain structural volumes mediated the association between GA and neurocognition, followed with a longitudinal analysis to track the changes.

RESULTS

Significant group differences were found in all neurocognitive scores, school achievements, and twenty-five cortical regional volumes (P < 0.05, Bonferroni corrected). Specifically, lower gestational ages were associated with graded lower cognition and school achievements and with smaller brain volumes of the fronto-parieto-temporal, fusiform, cingulate, insula, postcentral, hippocampal, thalamic, and pallidal regions. These lower brain volumes mediated the association between gestational age and cognitive function (P = 1 × 10^-8, β = 0.017, 95% CI: 0.007-0.028). Longitudinal analysis showed that compared to full term adolescents, preterm adolescents still had smaller brain volumes and crystallized intelligence scores at 11-12 years.

CONCLUSIONS

These results emphasize the relationships between gestational age at birth and adolescents' lower brain volume, and lower cognitive and educational performance, measured many years later when 9-10 and 11-12 years old. The study indicates the importance of early screening and close follow-up for neurocognitive and behavioral development for children and adolescents born with gestational ages that are even a little lower than full term.

Learning Curve for Flow Diversion of Posterior Circulation Aneurysms: A Long-Term International Multicenter Cohort Study

BACKGROUND AND PURPOSE

Flow diversion has gradually become a standard treatment for intracranial aneurysms of the anterior circulation. Recently, the off-label use of the flow diverters to treat posterior circulation aneurysms has also increased despite initial concerns of rupture and the suboptimal results. This study aimed to explore the change in complication rates and treatment outcomes across time for posterior circulation aneurysms treated using flow diversion and to further evaluate the mechanisms and variables that could potentially explain the change and outcomes.

MATERIALS AND METHODS

A retrospective review using a standardized data set at multiple international academic institutions was performed to identify patients with ruptured and unruptured posterior circulation aneurysms treated with flow diversion during a decade spanning January 2011 to January 2020. This period was then categorized into 4 intervals.

RESULTS

A total of 378 procedures were performed during the study period. Across time, there was an increasing tendency to treat more vertebral artery and fewer large vertebrobasilar aneurysms (P = .05). Moreover, interventionalists have been increasingly using fewer overlapping flow diverters per aneurysm (P = .07). There was a trend toward a decrease in the rate of thromboembolic complications from 15.8% in 2011-13 to 8.9% in 2018-19 (P = .34).

CONCLUSIONS

This multicenter experience revealed a trend toward treating fewer basilar aneurysms, smaller aneurysms, and increased usage of a single flow diverter, leading to a decrease in the rate of thromboembolic and hemorrhagic complications.

A model-based approach to assess reproducibility for large-scale high-throughput MRI-based studies

Magnetic Resonance Imaging (MRI) technology has been increasingly used in neuroscience studies. Reproducibility of statistically significant findings generated by MRI-based studies, especially association studies (phenotype vs. MRI metric) and task-induced brain activation, has been recently heavily debated. However, most currently available reproducibility measures depend on thresholds for the test statistics and cannot be use to evaluate overall study reproducibility. It is also crucial to elucidate the relationship between overall study reproducibility and sample size in an experimental design. In this study, we proposed a model-based reproducibility index to quantify reproducibility which could be used in large-scale high-throughput MRI-based studies including both association studies and task-induced brain activation. We performed the model-based reproducibility assessments for a few association studies and task-induced brain activation by using several recent large sMRI/fMRI databases. For large sample size association studies between brain structure/function features and some basic physiological phenotypes (i.e. Sex, BMI), we demonstrated that the model-based reproducibility of these studies is more than 0.99. For MID task activation, similar results could be observed. Furthermore, we proposed a model-based analytical tool to evaluate minimal sample size for the purpose of achieving a desirable model-based reproducibility. Additionally, we evaluated the model-based reproducibility of gray matter volume (GMV) changes for UK Biobank (UKB) vs. Parkinson Progression Marker Initiative (PPMI) and UK Biobank (UKB) vs. Human Connectome Project (HCP). We demonstrated that both sample size and study-specific experimental factors play important roles in the model-based reproducibility assessments for different experiments. In summary, a systematic assessment of reproducibility is fundamental and important in the current large-scale high-throughput MRI-based studies.

The brain structure and genetic mechanisms underlying the nonlinear association between sleep duration, cognition and mental health

Sleep duration, psychiatric disorders and dementias are closely interconnected in older adults. However, the underlying genetic mechanisms and brain structural changes are unknown. Using data from the UK Biobank for participants primarily of European ancestry aged 38-73 years, including 94% white people, we identified a nonlinear association between sleep, with approximately 7 h as the optimal sleep duration, and genetic and cognitive factors, brain structure, and mental health as key measures. The brain regions most significantly underlying this interconnection included the precentral cortex, the lateral orbitofrontal cortex and the hippocampus. Longitudinal analysis revealed that both insufficient and excessive sleep duration were significantly associated with a decline in cognition on follow up. Furthermore, mediation analysis and structural equation modeling identified a unified model incorporating polygenic risk score (PRS), sleep, brain structure, cognition and mental health. This indicates that possible genetic mechanisms and brain structural changes may underlie the nonlinear relationship between sleep duration and cognition and mental health.

[Diagnostic value of platelet associated biomarkers in chronic periprosthetic joint infection]

Objective: To evaluate the diagnostic value of platelet count(PC),PC to mean platelet volume(MPV) ratio(PC/MPV) and plateletcrit(PCT) in chronic periprosthetic joint infection(PJI). Method: The medical records of 159 patients who underwent hip or knee revisions at Department of Joint Surgery,Affiliated Hospital of Qingdao University from August 2013 to June 2019 were retrospectively reviewed. There were 51 patients(26 knees and 25 hips) in the PJI group,which included 28 males and 23 females,aged (68.0±11.8)years (range:32 to 84 years)with a body mass index(BMI)of (26.1±3.6) kg/m².There were 116 patients(19 knees and 97 hips) in the aseptic loosening(AL) group,including 67 males and 49 females,aged (70.3±8.9)years(range:49 to 89 years)with a BMI of (25.0±3.6)kg/m².The plasma C-reactive protein(CRP),erythrocyte sedimentation rate(ESR),PC,MPV,PC/MPV and PCT levels of the two groups were recorded and analyzed. Receiver operating characteristic curve was used to calculate the sensitivity and specificity of each biomarker,expect for MPV,and the diagnostic value of each biomarker was compared according to the area under the curve(AUC).Independent-sample t test or Mann-Whitney U test were used for comparison between groups. Result: Compared with AL group,AJI group had significantly higher levels of CRP,ESR,PC,PC/MPV and PCT(all P<0.05),but lower level of MPV (P<0.05).The AUCs for CRP,ESR,PC,PC/MPV and PCT were 0.820, 0.829, 0.689, 0.668 and 0.676,respectively. Based on the Youden index,the optimal predictive cutoff for CRP was 11.12 mg/L,with a sensitivity of 74.4% and a specificity of 87.1%.The optimal predictive cutoff for ESR was 17.60 mm/1 h,with a sensitivity of 81.4% and a specificity of 75.3%.The optimal predictive cutoff for PC was 243.00×109/L,with a sensitivity of 60.6% and a specificity of 71.8%.The optimal predictive cutoff for PC/MPV was 24.95,the sensitivity was 58.1% and the specificity was 74.1%.And the optimal predictive cutoff for PCT was 0.24%,with a sensitivity of 69.8% and a specificity of 63.5%. Conclusion: PC,PC to MPV ratio and PCT were of limited value to diagnose PJI.

rTMS alleviates cognitive and neural oscillatory deficits induced by hindlimb unloading in mice via maintaining balance between glutamatergic and GABAergic systems

Microgravity, as a part of the stress of space flight, has several negative effects on cognitive functions. Repetitive transcranial magnetic stimulation (rTMS), as a novel non-invasive technique, could be an effective approach to alleviated cognitive decline, applied in both preclinical and clinical studies. Neural oscillations and their interactions are involved in cognitive functions and support the communication of neural information. The neural oscillation could be a window from which we may understand what happens in the brain. The current study aimed to explore if 15 Hz rTMS plays a neural modulation role in a mouse model of hindlimb unloading. We hypothezed that rTMS can improve the cognitive and neural oscillatory deficits induced by hindlimb unloading via maintaining the balance between glutamatergic and GABAergic systems. Our data show that rTMS can significantly alleviate behavior deficits, modulate theta oscillation, improve the disturbed power distribution of theta oscillation and the decreased strength of Cross-Frequency Coupling in the dentate gyrus region, and effectively mitigated the blocked communication of neural information in the perforant pathway (PP)-dentate gyrus (DG) neural pathway in Hu mice. Furthermore, biochemical analysis using high-performance liquid chromatography and Western blot assay confirmed that rTMS increases the low expression of glutamate (Glu) and N-Methyl d-Aspartate receptor subtype 2B (NR2B) and decreases the high expression of γ-aminobutyric acid (GABA), 67 KDa isoform of glutamate decarboxylase (GAD67), and GABA type A receptor subunit alpha1 (GABAAR_α1) in the hippocampus of Hu mice. Taken together, the results suggest that rTMS plays a significant neural modulation role in the hippocampal neural activity disorders induced by Hu, which possibly depends on rTMS maintaining the balance of glutamatergic and gamma-aminobutyric acidergic (GABAergic) systems.

Knockdown of Follistatin-like 1 disrupts synaptic transmission in hippocampus and leads to cognitive impairments

Follistatin-like 1 (FSTL1), also named transforming growth factor (TGF)-β1-inducible gene, is a secreted extracellular glycoprotein expressing widely in nervous system. Several recent studies have revealed that FSTL1 plays an essential role in neurological diseases including neuropathic pain and ischemic stroke. It proves that FSTL1 suppresses synaptic transmission by activating Na/K-ATPase in DRG neurons and inhibits neuronal apoptosis by phosphorylation AKT signaling. However, it is not clear whether FSTL1 can play a role in other type of neuron or neurodegenerative diseases. In this study, we found that the mice with Fstl1 genetic knockdown showed not only the impairments of learning and memory abilities, but also abnormal neural oscillations and synaptic plasticity in the hippocampus. Subsequently, we identified broad transcriptional changes including 55 up-regulated and 184 down-regulated genes in Fstl1 knockdown mice by RNA-Seq analysis, as well as neurotransmitter transport, synaptic transmission and disease-related genes. The expression changes of some DEGs were further validated via quantitative Realtime PCR (qRT-PCR). Further patch-clamp whole cell recording showed that Fstl1^+/- mice displayed a significant decrease in glutamatergic synaptic transmission and increase in GABAergic synaptic transmission, which were consistent with the RNA-Seq analysis. Taken together, our results provide an evidence and a possibly underlying mechanism for the critical role of FSTL1 in the hippocampus on learning and memory and normal neural oscillations, suggesting that FSTL1 may plays an important role in neurodegenerative diseases related to cognitive impairments.

Risk factors of perioperative complications and transfusion following total hip arthroplasty in systemic lupus erythematosus patients

BACKGROUND

In recent years, hip arthroplasty rates in systemic lupus erythematosus (SLE) patients have been increasing rapidly. Although patients with SLE generally show beneficial or desirable functional outcomes following total hip arthroplasty (THA), it has been reported that SLE patients after THA have increased risk of postoperative complications, especially during the period of hospitalization.

OBJECTIVES

In the present study, we aimed to identify possible factors associated with complications or transfusion of THA in SLE patients during hospitalization.

METHODS

The present study was a retrospective study conducted in Peking Union Medical College Hospital. Data were collected from medical records of patients who underwent THA from January 2012 to June 2018. The primary outcome variable was perioperative complications, which was defined as having one or more of the following conditions: high fever, infection, impaired wound healing, venous thrombosis of the lower extremities, hematoma, arrhythmia, implant complications. The secondary outcome was perioperative transfusion.

RESULTS

During January 2012 to June 2018, 100 patients had taken the surgery of THA. After multivariate analysis, independent risk factors for perioperative complications were: age ≥ 45 years (p = 0.001), SLE with other connective tissue diseases (p = 0.029), high temperature (p = 0.030), positive anti-dsDNA antibody (p = 0.043), and Systemic Lupus International Collaborative Clinics/American College of Rheumatology (SLICC/ACR) Damage Index ≥ 3 (p = 0.008). Independent risk factors for perioperative transfusion were bilateral THA (p = 0.029), low hemoglobin (p = 0.021) and abnormal renal function (p = 0.021).

CONCLUSION

For SLE patients following THA, age > 45 years, SLE with other connective tissue disease, high temperature, positive anti-dsDNA antibody and SLICC/ACR Damage Index ≥ 3 were the risk factors of complications during hospitalization and bilateral THA, low hemoglobin and abnormal renal function were the risk factors of transfusion.

All-optical inhibitory dynamics in photonic neuron based on polarization mode competition in a VCSEL with an embedded saturable absorber

An all-optical spike inhibition scheme based on polarization-mode competition (PMC) in a vertical-cavity surface-emitting laser (VCSEL) with an embedded saturable absorber is proposed and investigated numerically. The inhibitory dynamics is characterized by spike amplitude and first-spike latency (FSL) for the first time, to the best of our knowledge. The effects of time differences between inhibitory and excitatory inputs, inputs strengths, bias current, as well as noise on the spike amplitude and FSL are examined. The results show that a spike can be triggered in the y-polarization mode by excitatory input and can be inhibited in the presence of inhibitory input due to PMC.

A Novel Rodent Orthotopic Forelimb Transplantation Model That Allows for Reliable Assessment of Functional Recovery Resulting From Nerve Regeneration

Improved nerve regeneration and functional outcomes would greatly enhance the utility of vascularized composite allotransplantation (VCA) such as hand and upper extremity transplantation. However, research aimed at achieving this goal has been limited by the lack of a functional VCA animal model. We have developed a novel rat midhumeral forelimb transplant model that allows for the characterization of upper extremity functional recovery following transplantation. At the final end point of 12 weeks, we found that animals with forelimb transplantation including median, ulnar and radial nerve coaptation demonstrated significantly improved grip strength and forelimb function as compared to forelimb transplantation without nerve approximation (grip strength: 1.71N ± 0.57 vs. no appreciable recovery; IBB scale: 2.6 ± 0.7? vs. 0.8 ± 0.40; p = 0.0005), and similar recovery to nerve transection-and-repair only (grip strength: 1.71N ± 0.57 vs. 2.03 ± 0.42.6; IBB scale: 2.6 ± 0.7 vs. 2.8 ± 0.8; p = ns). Moreover, all forelimb transplant animals with nerve coaptation displayed robust axonal regeneration with myelination and reduced flexor muscle atrophy when compared to forelimb transplant animals without nerve coaptation. In conclusion, this is the first VCA small-animal model that allows for reliable and reproducible measurement of behavioral functional recovery in addition to histologic evaluation of nerve regeneration and graft reinnervation.

Similar enhancement of BK(Ca) channel function despite different aerobic exercise frequency in aging cerebrovascular myocytes

Aerobic exercise showed beneficial influence on cardiovascular systems in aging, and mechanisms underlying vascular adaption remain unclear. Large-conductance Ca(2+)-activated K(+) (BK(Ca)) channels play critical roles in regulating cellular excitability and vascular tone. This study determined the effects of aerobic exercise on aging-associated functional changes in BK(Ca) channels in cerebrovascular myocytes, Male Wistar rats aged 20-22 months were randomly assigned to sedentary (O-SED), low training frequency (O-EXL), and high training frequency group (O-EXH). Young rats were used as control. Compared to young rats, whole-cell BK(Ca) current was decreased, and amplitude of spontaneous transient outward currents were reduced. The open probability and Ca(2+)/voltage sensitivity of single BK(Ca) channel were declined in O-SED, accompanied with a reduction of tamoxifen-induced BK(Ca) activation; the mean open time of BK(Ca) channels was shortened whereas close time was prolonged. Aerobic exercise training markedly alleviated the aging-associated decline independent of training frequency. Exercise three times rather than five times weekly may be a time and cost-saving training volume required to offer beneficial effects to offset the functional declines of BK(Ca) during aging.

Metal-insulator transition in the quasi-one-dimensional transport of fractional quantum Hall states

We investigate edge state transmission in quantum point contacts (QPCs) in the fractional quantum-Hall regime, finding behavior reminiscent of a metal-insulator transition. The transition is suggested by an unusual behavior of the differential conductance in the fractional-quantum-Hall regime, and by the presence of a fixed point and universal scaling in the temperature dependence of the linear conductance. Noting that the 0.7 feature evolves continuously into a last fractional plateau at high magnetic fields, we suggest that this still unresolved feature may itself be viewed as a manifestation of a local, microscopic, metal-insulator transition.

Sensory processing differences and urinary incontinence in school-aged children

OBJECTIVE

Urinary Incontinence (UI) is a common problem among school-aged children (5-11 years). Symptoms such as urgency, diminished awareness of wetting, or apparent apathy may represent differences in sensory processing (SP). This study aims to describe the SP abilities of incontinent school-aged children with typical development to determine if they differ from established norms for continent children.

MATERIALS AND METHODS

The SP abilities of 209 school-aged children with UI were evaluated using the short sensory profile (SSP), a judgment-based caregiver questionnaire, then compared with established norms using descriptive and inferential statistics.

RESULTS

Forty-four percent of children showed significant differences in global SP with the greatest differences noted in tactile sensitivity. Higher section subscores were also noted in "seeks sensation/under responsive" and "auditory sensitivity". Children with dysfunctional voiding (DV) were more likely to show global differences (p = 0.015), differences in "seeks sensation" (p = 0.006), and auditory sensitivity (p = 0.041). The odds for low tactile sensitivity scores were five times greater for children with UI and DV (p = 0.006).

CONCLUSION

These results suggest that differences in SP may be found among typical school aged children with UI. Continued research is indicated to understand the significance of the study results.

On the zero-bias anomaly and Kondo physics in quantum point contacts near pinch-off

We investigate the linear and non-linear conductance of quantum point contacts (QPCs), in the region near pinch-off where Kondo physics has previously been connected to the appearance of the 0.7 feature. In studies of seven different QPCs, fabricated in the same high-mobility GaAs/AlGaAs heterojunction, the linear conductance is widely found to show the presence of the 0.7 feature. The differential conductance, on the other hand, does not generally exhibit the zero-bias anomaly (ZBA) that has been proposed to indicate the Kondo effect. Indeed, even in the small subset of QPCs found to exhibit such an anomaly, the linear conductance does not always follow the universal temperature-dependent scaling behavior expected for the Kondo effect. Taken collectively, our observations demonstrate that, unlike the 0.7 feature, the ZBA is not a generic feature of low-temperature QPC conduction. We furthermore conclude that the mere observation of the ZBA alone is insufficient evidence for concluding that Kondo physics is active. While we do not rule out the possibility that the Kondo effect may occur in QPCs, our results appear to indicate that its observation requires a very strict set of conditions to be satisfied. This should be contrasted with the case of the 0.7 feature, which has been apparent since the earliest experimental investigations of QPC transport.

Hierarchical Bayesian modeling of heterogeneous variances in average daily weight gain of commercial feedlot cattle

Variability in ADG of feedlot cattle can affect profits, thus making overall returns more unstable. Hence, knowledge of the factors that contribute to heterogeneity of variances in animal performance can help feedlot managers evaluate risks and minimize profit volatility when making managerial and economic decisions in commercial feedlots. The objectives of the present study were to evaluate heteroskedasticity, defined as heterogeneity of variances, in ADG of cohorts of commercial feedlot cattle, and to identify cattle demographic factors at feedlot arrival as potential sources of variance heterogeneity, accounting for cohort- and feedlot-level information in the data structure. An operational dataset compiled from 24,050 cohorts from 25 U. S. commercial feedlots in 2005 and 2006 was used for this study. Inference was based on a hierarchical Bayesian model implemented with Markov chain Monte Carlo, whereby cohorts were modeled at the residual level and feedlot-year clusters were modeled as random effects. Forward model selection based on deviance information criteria was used to screen potentially important explanatory variables for heteroskedasticity at cohort- and feedlot-year levels. The Bayesian modeling framework was preferred as it naturally accommodates the inherently hierarchical structure of feedlot data whereby cohorts are nested within feedlot-year clusters. Evidence for heterogeneity of variance components of ADG was substantial and primarily concentrated at the cohort level. Feedlot-year specific effects were, by far, the greatest contributors to ADG heteroskedasticity among cohorts, with an estimated ∼12-fold change in dispersion between most and least extreme feedlot-year clusters. In addition, identifiable demographic factors associated with greater heterogeneity of cohort-level variance included smaller cohort sizes, fewer days on feed, and greater arrival BW, as well as feedlot arrival during summer months. These results support that heterogeneity of variances in ADG is prevalent in feedlot performance and indicate potential sources of heteroskedasticity. Further investigation of factors associated with heteroskedasticity in feedlot performance is warranted to increase consistency and uniformity in commercial beef cattle production and subsequent profitability.

Oscillation of clock and clock controlled genes induced by serum shock in human breast epithelial and breast cancer cells: regulation by melatonin

This study investigates differences in expression of clock and clock-controlled genes (CCGs) between human breast epithelial and breast cancer cells and breast tumor xenografts in circadian intact rats and examines if the pineal hormone melatonin influences clock gene and CCG expression. Oscillation of clock gene expression was not observed under standard growth conditions in vitro, however, serum shock (50% horse serum for 2 h) induced oscillation of clock gene and CCG expression in MCF-10A cells, which was repressed or disrupted in MCF-7 cells. Melatonin administration following serum shock differentially suppressed or induced clock gene (Bmal1 and Per2) and CCG expression in MCF10A and MCF-7 cells. These studies demonstrate the lack of rhythmic expression of clock genes and CCGs of cells in vitro and that transplantation of breast cancer cells as xenografts into circadian competent hosts re-establishes a circadian rhythm in the peripheral clock genes of tumor cells.

Combined hepatocellular cholangiocarcinoma originating from hepatic progenitor cells: immunohistochemical and double-fluorescence immunostaining evidence

AIMS

Combined hepatocellular cholangiocarcinoma (CHC) is a rare form of primary liver cancer, showing a mixture of hepatocellular and biliary features. Data suggest that most CHC arise from hepatic progenitor cells (HPCs). The aim was to investigate the origin of CHC.

METHODS AND RESULTS

Twelve cases of CHC were studied by immunohistochemistry for hepatocytic (hepPar1, alpha-fetoprotein), cholangiocytic cytokeratin [(CK) 7, CK19], hepatic progenitor cell (OV-6), haematopoietic stem cell (c-kit, CD34), as well as CD45 and chromogranin-A markers. The combination of double-fluorescence immunostaining consisted of HepPar1 with CK19, and c-kit with OV-6. All 12 cases demonstrated more or less transitional areas, with strands/trabeculae of small, uniform, oval-shaped cells including scant cytoplasm and hyperchromatic nuclei embedded within a thick, desmoplastic stroma; however, two cases were found to consist entirely of such transitional areas. Simultaneous co-expression of hepPar1 and CK7, or CK19, was demonstrated in 10/12 (83.3%) cases of CHC. c-kit expression was noted in 10/12 (83.3%) cases, of which 7/10 (70%) showed co-expression of OV-6.

CONCLUSIONS

The results suggest that CHC are of HPC origin, supporting the concept that human hepatocarcinogenesis may originate from the transformation of HPCs.

Entropy maximization constrained by solvent flatness: a new method for macromolecular phase extension and map improvement

A practical generally applicable procedure for exponential modeling to maximum likelihood of macromolecular data sets constrained by a moderately large basis set of reliable phases and a molecular envelope is described, based on the computer program MICE [Bricogne & Gilmore (1990). Acta Cryst. A46, 284-297]. Procedures were first tested with simulated data sets. Exact and randomly perturbed amplitudes and phases were generated, together with a known envelope for solvent-free protein and for protein in an electron-dense crystal mother liquor typical of many real protein crystals. These experiments established useful guidelines and values for various parameters. Tests with basis sets chosen from the largest amplitudes indicate that exponential models with considerable correct extrapolated phase and amplitude information can be constructed from as few as 16% of the total number of reflections, with mean phase errors of about 30 degrees, at resolution limits of either 5 or 3 A. When the shape of the solvent channels in macromolecular crystals is known, it offers an important additional source of information. MICE was, therefore, adapted to average the density outside the molecular boundary defined by an input envelope. This flattening process imposes a uniform density distribution in solvent-filled channels as an additional constraint on the exponential model and is analogous to the treatment of solvent in conventional solvent flattening. Experimental data for cytidine deaminase, a structure recently solved by making extensive use of conventional solvent flattening, provides an example of the performance of maximum-entropy methods in a real situation and a compelling comparison of this method to standard procedures. Exponential models of the electron density constrained by the most reliable phases obtained by multiple isomorphous replacement with anomalous scattering (MIRAS) (figure of merit > 0.7, representing 34% of the total number of reflections) and by the envelope give rise to centroid electron-density maps which are quantitatively superior by numerous statistical criteria to conventionally solvent-flattened density. Similarity of these maps to the 2F(obs) - F(calc) map calculated with phases obtained after crystallographic refinement of the model implies that maximum-entropy extrapolation provides better phases for the remaining 66% of the reflections than the original centroid MIRAS distributions. Importantly, the solvent-flattened electron density, although it did permit interpretation of the map which was not readily accomplished with the MIRAS map, contains substantial errors. It is proposed that errors of this sort may account for previously noted deficiencies of the solvent-flattening method [Fenderson, Herriott & Adman (1990). J. Appl. Cryst. 23, 115-131] and for the occasional tendency of incorrect interpretations to be 'locked in' by crystallographic refinement [Brändén & Jones (1990). Nature (London), 343, 687-689, and references cited therein]. Solvent flattening with combined maximization of entropy and likelihood represents a phase-refinement path independent of atomic models, using the experimental amplitudes and the most reliable phases. It should, therefore, become a valuable and generally useful procedure in macromolecular crystal structure determination.

MR Quantification of Flow in Children with Vein of Galen Malformations

SUMMARY

Vein of Galen vascular malformations are either Vein of Galen Aneurysmal malformations (VGAMs) or Vein of Galen Aneurysmal Dilatations (VGADs). VGAMs may be of the choroidal or mural type and are fistulas associated with the precursor of the vein of Galen. The treatment of VGAMs is aimed at controlling the size of the vascular shunt since it is believed that the shunt is responsible for venous hypertension, cardiac stress, delayed development and may be so large as to damage the brain. In VGAMs as noted by Berenstein and Lasjaunias. Absolute measures of flow may contribute to our understanding of CNS disease and permit objective measures of the success or failure of therapeutic interventions (5). MR phase contrast cine angiographic techniques can be employed to measure bulk flow in intracranial vessels. Vein of Galen vascular malformations are an ideal model to measure venous flow as the draining vein is large and angiographic evaluation is limited. Thus our goal was to develop an objective non-invasive method of measuring vascular flow in VGAMs and VGADs (6) . Herein we report our experience using this technique in a group of patients with Vein of Galen vascular malformations. We also hypothesized that the degree of shunting would correlate to the degree of cardiac stress and be an indicator of optimal timing for intervention. We believe that we have succeeded in our goal to develop an objective, non-invasive method of shunt quantification using velocity encoded MR sequences. This promises new insight into the hemodynamics, natural history and treatment response of vascular malformations.

On the relationship between protein stability and folding kinetics: a comparative study of the N-terminal domains of RNase HI, E. coli and Bacillus stearothermophilus L9

There is currently a great deal of interest in proteins that fold in a single highly cooperative step. Particular attention has been focused on elucidating the factors that govern folding rates of simple proteins. Recently, the topology of the native state has been proposed to be the most important determinant of their folding rates. Here we report a comparative study of the folding of three topologically equivalent proteins that adapt a particularly simple alpha/beta fold. The folding kinetics of the N-terminal domain of RNase HI and the N-terminal domain of the ribosomal protein L9 from Escherichia coli (eNTL9) were compared to the previously characterized N-terminal domain of L9 from Bacillus stearothermophilus (bNTL9). This 6.2 kDa protein, which is one of simplest examples of the ABCalphaD motif, folds via a two-state mechanism on the millisecond to submillisecond time scale. The RNase HI domain and bNTL9 have very similar tertiary structures but there is little similarity in primary sequence. bNTL9 and eNTL9 share the same biological function and a similar primary sequence but differ significantly in stability. Fluorescence-detected stopped-flow experiments showed that the three proteins fold in a two-state fashion. The folding rates in the absence of denaturant were found to be very different, ranging form 21 s(-1) to 790 s(-1) at 10 degrees C. The diverse folding rates appear to reflect large differences in the stability of the proteins. When compared at an isostability point, the folding rates converged to a similar value and there is a strong linear correlation between the log of the folding rate and stability for this set of proteins. These observations are consistent with the idea that stability can play an important role in dictating relative folding rates among topologically equivalent proteins.

Binding of low density lipoproteins to lipoprotein lipase is dependent on lipids but not on apolipoprotein B

Lipoprotein lipase (LPL) efficiently mediates the binding of lipoprotein particles to lipoprotein receptors and to proteoglycans at cell surfaces and in the extracellular matrix. It has been proposed that LPL increases the retention of atherogenic lipoproteins in the vessel wall and mediates the uptake of lipoproteins in cells, thereby promoting lipid accumulation and plaque formation. We investigated the interaction between LPL and low density lipoproteins (LDLs) with special reference to the protein-protein interaction between LPL and apolipoprotein B (apoB). Chemical modification of lysines and arginines in apoB or mutation of its main proteoglycan binding site did not abolish the interaction of LDL with LPL as shown by surface plasmon resonance (SPR) and by experiments with THP-I macrophages. Recombinant LDL with either apoB100 or apoB48 bound with similar affinity. In contrast, partial delipidation of LDL markedly decreased binding to LPL. In cell culture experiments, phosphatidylcholine-containing liposomes competed efficiently with LDL for binding to LPL. Each LDL particle bound several (up to 15) LPL dimers as determined by SPR and by experiments with THP-I macrophages. A recombinant NH(2)-terminal fragment of apoB (apoB17) bound with low affinity to LPL as shown by SPR, but this interaction was completely abolished by partial delipidation of apoB17. We conclude that the LPL-apoB interaction is not significant in bridging LDL to cell surfaces and matrix components; the main interaction is between LPL and the LDL lipids.

The distinct roles of T cell-derived cytokines and a novel follicular dendritic cell-signaling molecule 8D6 in germinal center-B cell differentiation

Germinal center-B (GC-B) cells differentiate into memory B cells and plasma cells (PC) through interaction with T cells and follicular dendritic cells (FDC). Activated T cell and FDC play distinct roles in this process. The detailed kinetic experiments revealed that cytokines secreted by activated T cells determined the pathway of GC-B cell differentiation. IL-4 directs GC-B cells to differentiate into memory B cells, whereas IL-10 steers them into PC. FDC/HK cells do not direct either pathway, but provide signals for proliferation of GC-B cells. A novel FDC-signaling molecule 8D6 (FDC-SM-8D6) produced by FDC augments PC generation in the GC. FDC-SM-8D6-specific mAb blocked PC generation and IgG secretion but not memory B cell proliferation. COS cells expressing FDC-SM-8D6 enhanced GC-B cell proliferation and Ab secretion, which was blocked by mAb 8D6. In the cultures with B cell subsets, PC generation was inhibited by mAb 8D6 in the cultures with CD27(+) B cells but not in the culture with CD27(-) B cells, suggesting that CD27(+) PC precursor is the specific target of FDC-SM-8D6 stimulation.

The crystal structure of Escherichia coli MoeA and its relationship to the multifunctional protein gephyrin

BACKGROUND

Molybdenum cofactor (Moco) biosynthesis is an evolutionarily conserved pathway present in archaea, eubacteria, and eukaryotes. In humans, genetic abnormalities in the biosynthetic pathway result in Moco deficiency, which is accompanied by severe neurological symptoms and death shortly after birth. The Escherichia coli MoeA and MogA proteins are involved in the final step of Moco biosynthesis: the incorporation of molybdenum into molybdopterin (MPT), the organic pyranopterin moiety of Moco.

RESULTS

The crystal structure of E. coli MoeA has been refined at 2 A resolution and reveals that the highly elongated MoeA monomer consists of four clearly separated domains, one of which is structurally related to MogA, indicating a divergent evolutionary relationship between both proteins. The active form of MoeA is a dimer, and a putative active site appears to be localized to a cleft formed between domain II of the first monomer and domains III and IV of the second monomer.

CONCLUSIONS

In eukaryotes, MogA and MoeA are fused into a single polypeptide chain. The corresponding mammalian protein gephyrin has also been implicated in the anchoring of glycinergic receptors to the cytoskeleton at inhibitory synapses. Based on the structures of MoeA and MogA, gephyrin is surmised to be a highly organized molecule containing at least five domains. This multidomain arrangement could provide a structural basis for its functional diversity. The oligomeric states of MoeA and MogA suggest how gephyrin could assemble into a hexagonal scaffold at inhibitory synapses.

Non-Hodgkin Lymphomas of Mice

Studies of lymphoid neoplasms occurring in normal or genetically engineered mice have revealed parallels and differences to non-Hodgkin lymphomas (NHL) of humans. Some mouse lymphomas have strong histologic similarities to the human NHL subsets including precursor B- and T-cell lymphoblastic, small lymphocytic, splenic marginal zone, and diffuse large-cell B-cell lymphomas (DLCL); whether molecular parallels also exist is under study. Others mouse types such as sIg+ lymphoblastic B-cell lymphoma have no histologic equivalent in human NHL even though they share molecular deregulation of BCL6 with human DLCL. Finally, Burkitt lymphoma does not appear to occur naturally in mice, but it can be induced with appropriately engineered transgenes.