The neural origin for asymmetric coding of surface color in the primate visual cortex

The coding privilege of end-spectral hues (red and blue) in the early visual cortex has been reported in primates. However, the origin of such bias remains unclear. Here, we provide a complete picture of the end-spectral bias in visual system by measuring fMRI signals and spiking activities in macaques. The correlated end-spectral biases between the LGN and V1 suggest a subcortical source for asymmetric coding. Along the ventral pathway from V1 to V4, red bias against green peaked in V1 and then declined, whereas blue bias against yellow showed an increasing trend. The feedforward and recurrent modifications of end-spectral bias were further revealed by dynamic causal modeling analysis. Moreover, we found that the strongest end-spectral bias in V1 was in layer 4C[Formula: see text]. Our results suggest that end-spectral bias already exists in the LGN and is transmitted to V1 mainly through the parvocellular pathway, then embellished by cortical processing.

Reirradiation vs. Systemic Therapy vs. Combination Therapy for Recurrent High-Grade Glioma: A Meta-Analysis of Survival and Toxicity

PURPOSE/OBJECTIVE(S)

To compare the effects of reirradiation, systemic therapy and combination therapy (reirradiation + systemic therapy) on overall survival (OS), progression-free survival (PFS) and adverse effects (AEs) in patients with recurrent high-grade glioma (rHGG).

MATERIALS/METHODS

A search was performed on PubMed, Scopus, Embase and CENTRAL on 18 March 2022, and repeated on 1 November 2022. Studies comparing OS, PFS and AEs in patients with rHGG, and encompassing the following four groups were included; reirradiation vs systemic therapy, combination therapy vs systemic therapy, combination therapy vs reirradiation, and reirradiation + bevacizumab-based systemic therapy vs reirradiation +/- non-bevacizumab-based systemic therapy. Risk of bias was assessed using the Cochrane RoB 2 tool for randomized control trials (RCTs) and the ROBINS-I tool for non-randomized studies. The logHR and SE (logHR) for OS and PFS, and logRR and SE (logRR) for AEs were extracted or estimated if not reported. Meta-analyses were performed for each comparator group using a random effects model. Subgroup analysis was performed on only RCTs if ≥ 2 studies were available.

RESULTS

Thirty-three studies comprising of 2201 participants were included. In the reirradiation vs systemic therapy group, there was no difference in PFS (2 studies, 185 participants; HR 0.87 (95% CI 0.61-1.22)) and OS (3 studies, 237 participants; HR 0.94 (95% CI 0.67-1.31)). In the combination therapy vs systemic therapy group, combination therapy improved PFS (6 studies, 605 participants; HR = 0.70 (95% CI 0.59-0.82)) and OS (6 studies, 537 participants; HR 0.73 (95% CI 0.56-0.96)), and there was no difference in grade 3+ AEs (4 studies, 398 participants; RR 1.03 (95% CI 0.57-1.86)). Subgroup analysis of only RCTs (2 studies, 205 participants) similarly showed no difference in grade 3+ AEs (RR 1.13 (95% CI 0.71-1.82)), though no significant improvements in PFS (HR 0.51 (95% CI 0.22-1.19)) or OS (HR 0.90 (95% CI 0.65-1.26)) were demonstrated. In the combination therapy vs reirradiation group, combination therapy improved PFS (5 studies, 259 participants; HR 0.50 (95% CI 0.37-0.69)) and OS (13 studies, 713 participants; HR 0.59 (95% CI 0.47-0.74)). In the reirradiation + bevacizumab-based systemic therapy vs reirradiation +/- non-bevacizumab-based systemic therapy group, combining reirradiation with bevacizumab improved PFS (2 studies, 104 participants; HR 0.46 (95% CI 0.27-0.77)) and OS (5 studies, 256 participants; HR 0.42 (95% CI 0.24-0.72)), and reduced radionecrosis (RN) (5 studies, 353 participants; RR 0.17 (95% CI 0.06-0.48)).

CONCLUSION

Combination therapy may improve OS and PFS with acceptable toxicity in select patients with rHGG. Further RCTs comparing systemic therapy to combination therapy, particularly with bevacizumab-based systemic therapy, are needed. The limitations of previous RCTs must be addressed; namely inadequate accrual of appropriate patients, and exclusion of FLAIR abnormalities from target delineation.

Dynamic Recruitment of the Feedforward and Recurrent Mechanism for Black-White Asymmetry in the Primary Visual Cortex

Black and white information is asymmetrically distributed in natural scenes, evokes asymmetric neuronal responses, and causes asymmetric perceptions. Recognizing the universality and essentiality of black-white asymmetry in visual information processing, the neural substrates for black-white asymmetry remain unclear. To disentangle the role of the feedforward and recurrent mechanisms in the generation of cortical black-white asymmetry, we recorded the V1 laminar responses and LGN responses of anesthetized cats of both sexes. In a cortical column, we found that black-white asymmetry starts at the input layer and becomes more pronounced in the output layer. We also found distinct dynamics of black-white asymmetry between the output layer and the input layer. Specifically, black responses dominate in all layers after stimulus onset. After stimulus offset, black and white responses are balanced in the input layer, but black responses still dominate in the output layer. Compared with that in the input layer, the rebound response in the output layer is significantly suppressed. The relative suppression strength evoked by white stimuli is notably stronger and depends on the location within the ON-OFF cortical map. A model with delayed and polarity-selective cortical suppression explains black-white asymmetry in the output layer, within which prominent recurrent connections are identified by Granger causality analysis. In addition to black-white asymmetry in response strength, the interlaminar differences in spatial receptive field varied dynamically. Our findings suggest that the feedforward and recurrent mechanisms are dynamically recruited for the generation of black-white asymmetry in V1.SIGNIFICANCE STATEMENT Black-white asymmetry is universal and essential in visual information processing, yet the neural substrates for cortical black-white asymmetry remain unknown. Leveraging V1 laminar recordings, we provided the first laminar pattern of black-white asymmetry in cat V1 and found distinct dynamics of black-white asymmetry between the output layer and the input layer. Comparing black-white asymmetry across three visual hierarchies, the LGN, V1 input layer, and V1 output layer, we demonstrated that the feedforward and recurrent mechanisms are dynamically recruited for the generation of cortical black-white asymmetry. Our findings not only enhance our understanding of laminar processing within a cortical column but also elucidate how feedforward connections and recurrent connections interact to shape neuronal response properties.

Engineering of NEMO as calcium indicators with large dynamics and high sensitivity

Genetically encoded calcium indicators (GECIs) are indispensable tools for real-time monitoring of intracellular calcium signals and cellular activities in living organisms. Current GECIs face the challenge of suboptimal peak signal-to-baseline ratio (SBR) with limited resolution for reporting subtle calcium transients. We report herein the development of a suite of calcium sensors, designated NEMO, with fast kinetics and wide dynamic ranges (>100-fold). NEMO indicators report Ca²⁺ transients with peak SBRs around 20-fold larger than the top-of-the-range GCaMP6 series. NEMO sensors further enable the quantification of absolution calcium concentration with ratiometric or photochromic imaging. Compared with GCaMP6s, NEMOs could detect single action potentials in neurons with a peak SBR two times higher and a median peak SBR four times larger in vivo, thereby outperforming most existing state-of-the-art GECIs. Given their high sensitivity and resolution to report intracellular Ca²⁺ signals, NEMO sensors may find broad applications in monitoring neuronal activities and other Ca²⁺-modulated physiological processes in both mammals and plants.

V1-bypassing suppression leads to direction-specific microsaccade modulation in visual coding and perception

Microsaccades play a critical role in refreshing visual information and have been shown to have direction-specific influences on human perception. However, the neural mechanisms underlying such direction-specific effects remains unknown. Here, we report the emergence of direction-specific microsaccade modulation in the middle layer of V2 but not in V1: responses of V2 neurons after microsaccades moved toward their receptive fields were stronger than those when microsaccades moved away. The decreased responses from V1 to V2, which are correlated with the amplitude of microsaccades away from receptive fields, suggest topographically location-specific suppression from an oculomotor source. Consistent with directional effects in V2, microsaccades function as a guide for monkeys' behavior in a peripheral detection task; both can be explained by a dynamic neural network. Our findings suggest a V1-bypassing suppressive circuit for direction-specific microsaccade modulation in V2 and its functional influence on visual sensitivity, which highlights the optimal sampling nature of microsaccades.

Compensatory mechanism of attention-deficit/hyperactivity disorder recovery in resting state alpha rhythms

Alpha rhythms in the human electroencephalogram (EEG), oscillating at 8-13 Hz, are located in parieto-occipital cortex and are strongest when awake people close their eyes. It has been suggested that alpha rhythms were related to attention-related functions and mental disorders (e.g., Attention-deficit/hyperactivity disorder (ADHD)). However, many studies have shown inconsistent results on the difference in alpha oscillation between ADHD and control groups. Hence it is essential to verify this difference. In this study, a dataset of EEG recording (128 channel EGI) from 87 healthy controls (HC) and 162 ADHD (141 persisters and 21 remitters) adults in a resting state with their eyes closed was used to address this question and a three-gauss model (summation of baseline and alpha components) was conducted to fit the data. To our surprise, the power of alpha components was not a significant difference among the three groups. Instead, the baseline power of remission and HC group in the alpha band is significantly stronger than that of persister groups. Our results suggest that ADHD recovery may have compensatory mechanisms and many abnormalities in EEG may be due to the influence of behavior rather than the difference in brain signals.

Transesophageal echocardiography-guided implantation of totally implantable venous access devices via the internal jugular vein: retrospective analysis of 297 cases in pediatric patients

BACKGROUND

Accurately positioning totally implantable venous access device (TIVAD) catheters and reducing complications in pediatric patients are important and challenging. A number of studies have shown methods for locating the tip of the TIVAD catheter. We assessed the success and complications of TIVAD implantation guided by transesophageal echocardiography (TEE) via the internal jugular vein (IJV) for 294 patients in this retrospective study.

METHODS

From May 2019 to March 2021, 297 cases of TIVADs in our hospital were analyzed in this observational, non-randomized, single-center study. The position of the catheter tip under TEE and chest radiography and rates of periprocedural, early, and late complications were evaluated.

RESULTS

The implantation was successful in 242 (82.3%) cases which was in a proper position, and the results were consistent with those of postoperative chest radiography. A total of 72 complications were recorded. Of these, 1 case had a perioperative complication, 66 had early complications, and 5 had late complications after port implantation. The most common complications were local infection and catheter malposition, namely 10 (13.9%) cases of incision infection and 58 (80.6%) cases of catheter malposition. In total, 6 (8.3%) cases of port explantation were required.

CONCLUSION

Confirmation of proper TIVAD catheter positioning by TEE through an internal jugular approach in children was accurate and safe.

Cascaded normalizations for spatial integration in the primary visual cortex of primates

Spatial integration of visual information is an important function in the brain. However, neural computation for spatial integration in the visual cortex remains unclear. In this study, we recorded laminar responses in V1 of awake monkeys driven by visual stimuli with grating patches and annuli of different sizes. We find three important response properties related to spatial integration that are significantly different between input and output layers: neurons in output layers have stronger surround suppression, smaller receptive field (RF), and higher sensitivity to grating annuli partially covering their RFs. These interlaminar differences can be explained by a descriptive model composed of two global divisions (normalization) and a local subtraction. Our results suggest suppressions with cascaded normalizations (CNs) are essential for spatial integration and laminar processing in the visual cortex. Interestingly, the features of spatial integration in convolutional neural networks, especially in lower layers, are different from our findings in V1.

[Development of a Ranking Tool for Scientificity, Transparency and Applicability of Clinical Practice Guidelines]

Objective: To address the limitations of existing methods and tools for evaluating clinical practice guidelines, we aimed to develop a comprehensive instrument focusing on the three main dimensions of guideline development: scientificity, transparency, applicability. We will use it to rank the guidelines according to the scores. We abbreviated it as STAR, and its reliability, validity and usability were also tested. Methods: A multidisciplinary expert working group was set up, including methodologists, statisticians, journal editors, medical professionals, and others. Scoping review, Delphi methods and hierarchical analysis were used to determine the final checklist of STAR. Results: The new instrument contained 11 domains and 39 items. Intrinsic reliability of each domain was indicated by Cronbach's α coefficient, with a average value of 0.646. The Cohen's kappa coefficients for methodological evaluators and clinical evaluators were 0.783 and 0.618. The overall content validity index was 0.905. The R2 for the criterion validity analysis was 0.76. The average score for usability of the items was 4.6, and the mean time spent to evaluate each guideline was 20 minutes. Conclusion: The instrument has good reliability, validity and evaluating efficiency, and can be used for evaluating and ranking guidelines more comprehensively.

[Correlation analysis between children and adolescents watching food TV advertising and fast food consumption]

Based on the open data of China Health and Nutrition Survey (CHNS), 249 children, adolescents and 249 heads of families who completed two rounds of surveys in 2011 and 2015 were selected in this study. According to the fast food consumption of children and adolescents, they were divided into fast food consumption group and non-fast food consumption group. Logistic regression model was used to analyze the relationship between children and adolescents watching Food TV advertising and fast food consumption. After adjusting relevant factors, the results showed that children and adolescents requiring their parents to buy food in TV advertisements (OR=3.122, P=0.001), parents buying food for their children in TV advertisements (OR=4.717, P=0.036), children and adolescents buying food in TV advertisements themselves (OR=3.728, P=0.041), children and adolescents' preference for food in TV advertisements (OR=2.946, P=0.044) and the frequency of children and adolescents reported by their parents asking their parents to buy food in TV advertisements (OR=3.113, P=0.002) were associated with children and adolescents' fast food consumption.

Coding strategy for surface luminance switches in the primary visual cortex of the awake monkey

Both surface luminance and edge contrast of an object are essential features for object identification. However, cortical processing of surface luminance remains unclear. In this study, we aim to understand how the primary visual cortex (V1) processes surface luminance information across its different layers. We report that edge-driven responses are stronger than surface-driven responses in V1 input layers, but luminance information is coded more accurately by surface responses. In V1 output layers, the advantage of edge over surface responses increased eight times and luminance information was coded more accurately at edges. Further analysis of neural dynamics shows that such substantial changes for neural responses and luminance coding are mainly due to non-local cortical inhibition in V1’s output layers. Our results suggest that non-local cortical inhibition modulates the responses elicited by the surfaces and edges of objects, and that switching the coding strategy in V1 promotes efficient coding for luminance.

How brightness is encoded in the visual cortex remains incompletely understood. By recording from macaque V1, the authors revealed a switch from surface to edge encoding that is mediated by widespread inhibition in the output layers of the cortex.

Multiple gamma rhythms carry distinct spatial frequency information in primary visual cortex

Gamma rhythms in many brain regions, including the primary visual cortex (V1), are thought to play a role in information processing. Here, we report a surprising finding of 3 narrowband gamma rhythms in V1 that processed distinct spatial frequency (SF) signals and had different neural origins. The low gamma (LG; 25 to 40 Hz) rhythm was generated at the V1 superficial layer and preferred a higher SF compared with spike activity, whereas both the medium gamma (MG; 40 to 65 Hz), generated at the cortical level, and the high gamma HG; (65 to 85 Hz), originated precortically, preferred lower SF information. Furthermore, compared with the rates of spike activity, the powers of the 3 gammas had better performance in discriminating the edge and surface of simple objects. These findings suggest that gamma rhythms reflect the neural dynamics of neural circuitries that process different SF information in the visual system, which may be crucial for multiplexing SF information and synchronizing different features of an object.

Dissecting cascade computational components in spiking neural networks

Finding out the physical structure of neuronal circuits that governs neuronal responses is an important goal for brain research. With fast advances for large-scale recording techniques, identification of a neuronal circuit with multiple neurons and stages or layers becomes possible and highly demanding. Although methods for mapping the connection structure of circuits have been greatly developed in recent years, they are mostly limited to simple scenarios of a few neurons in a pairwise fashion; and dissecting dynamical circuits, particularly mapping out a complete functional circuit that converges to a single neuron, is still a challenging question. Here, we show that a recent method, termed spike-triggered non-negative matrix factorization (STNMF), can address these issues. By simulating different scenarios of spiking neural networks with various connections between neurons and stages, we demonstrate that STNMF is a persuasive method to dissect functional connections within a circuit. Using spiking activities recorded at neurons of the output layer, STNMF can obtain a complete circuit consisting of all cascade computational components of presynaptic neurons, as well as their spiking activities. For simulated simple and complex cells of the primary visual cortex, STNMF allows us to dissect the pathway of visual computation. Taken together, these results suggest that STNMF could provide a useful approach for investigating neuronal systems leveraging recorded functional neuronal activity.

It is well known that the computation of neuronal circuits is carried out through the staged and cascade structure of different types of neurons. Nevertheless, the information, particularly sensory information, is processed in a network primarily with feedforward connections through different pathways. A peculiar example is the early visual system, where light is transcoded by the retinal cells, routed by the lateral geniculate nucleus, and reached the primary visual cortex. One meticulous interest in recent years is to map out these physical structures of neuronal pathways. However, most methods so far are limited to taking snapshots of a static view of connections between neurons. It remains unclear how to obtain a functional and dynamical neuronal circuit beyond the simple scenarios of a few randomly sampled neurons. Using simulated spiking neural networks of visual pathways with different scenarios of multiple stages, mixed cell types, and natural image stimuli, we demonstrate that a recent computational tool, named spike-triggered non-negative matrix factorization, can resolve these issues. It enables us to recover the entire structural components of neural networks underlying the computation, together with the functional components of each individual neuron. Utilizing it for complex cells of the primary visual cortex allows us to reveal every underpinning of the nonlinear computation. Our results, together with other recent experimental and computational efforts, show that it is possible to systematically dissect neural circuitry with detailed structural and functional components.

Superimposed gratings induce diverse response patterns of gamma oscillations in primary visual cortex

Stimulus-dependence of gamma oscillations (GAMMA, 30-90 Hz) has not been fully understood, but it is important for revealing neural mechanisms and functions of GAMMA. Here, we recorded spiking activity (MUA) and the local field potential (LFP), driven by a variety of plaids (generated by two superimposed gratings orthogonal to each other and with different contrast combinations), in the primary visual cortex of anesthetized cats. We found two distinct narrow-band GAMMAs in the LFPs and a variety of response patterns to plaids. Similar to MUA, most response patterns showed that the second grating suppressed GAMMAs driven by the first one. However, there is only a weak site-by-site correlation between cross-orientation interactions in GAMMAs and those in MUAs. We developed a normalization model that could unify the response patterns of both GAMMAs and MUAs. Interestingly, compared with MUAs, the GAMMAs demonstrated a wider range of model parameters and more diverse response patterns to plaids. Further analysis revealed that normalization parameters for high GAMMA, but not those for low GAMMA, were significantly correlated with the discrepancy of spatial frequency between stimulus and sites' preferences. Consistent with these findings, normalization parameters and diversity of high GAMMA exhibited a clear transition trend and region difference between area 17 to 18. Our results show that GAMMAs are also regulated in the form of normalization, but that the neural mechanisms for these normalizations might differ from those of spiking activity. Normalizations in different brain signals could be due to interactions of excitation and inhibitions at multiple stages in the visual system.

The Generation and Modulation of Distinct Gamma Oscillations with Local, Horizontal, and Feedback Connections in the Primary Visual Cortex: A Model Study on Large-Scale Networks

Gamma oscillation (GAMMA) in the local field potential (LFP) is a synchronized activity commonly found in many brain regions, and it has been thought as a functional signature of network connectivity in the brain, which plays important roles in information processing. Studies have shown that the response property of GAMMA is related to neural interaction through local recurrent connections (RC), feed-forward (FF), and feedback (FB) connections. However, the relationship between GAMMA and long-range horizontal connections (HC) in the brain remains unclear. Here, we aimed to understand this question in a large-scale network model for the primary visual cortex (V1). We created a computational model composed of multiple excitatory and inhibitory units with biologically plausible connectivity patterns for RC, FF, FB, and HC in V1; then, we quantitated GAMMA in network models at different strength levels of HC and other connection types. Surprisingly, we found that HC and FB, the two types of large-scale connections, play very different roles in generating and modulating GAMMA. While both FB and HC modulate a fast gamma oscillation (around 50-60 Hz) generated by FF and RC, HC generates a new GAMMA oscillating around 30 Hz, whose power and peak frequency can also be modulated by FB. Furthermore, response properties of the two GAMMAs in a network with both HC and FB are different in a way that is highly consistent with a recent experimental finding for distinct GAMMAs in macaque V1. The results suggest that distinct GAMMAs are signatures for neural connections in different spatial scales and they might be related to different functions for information integration. Our study, for the first time, pinpoints the underlying circuits for distinct GAMMAs in a mechanistic model for macaque V1, which might provide a new framework to study multiple gamma oscillations in other cortical regions.

Ultrasonic evaluation of systemic and renal perfusion in sepsis patients before and after fluid resuscitation

OBJECTIVE

This study aimed to explore the significance of renal Doppler ultrasound in evaluating systemic and renal perfusion in sepsis patients before and after fluid resuscitation.

PATIENTS AND METHODS

Forty sepsis patients admitted to the Department of Intensive Medicine and intensive care unit (ICU) of the Fourth Hospital of Hebei Medical University from June 2014 to December 2014 were enrolled in this study, and 35 patients were included in the final analysis. These patients were divided into positive and negative fluid responsiveness groups. They were also divided into an acute kidney injury (AKI) group and a non-AKI group according to changes in creatinine and urine volume. The correlations of the changes in hemodynamics before and after fluid resuscitation in each group with the changes in renal resistance index (RRI) and renal blood flow (RBF) grades were evaluated.

RESULTS

Before and after fluid resuscitation, the heart rate (HR), blood creatinine (Cre), and lactate (Lac) levels of all patients, including the patients in the positive fluid responsiveness group decreased, and the stroke volume (SV) and central venous pressure (CVP) increased. Only HR decreased in the negative fluid responsiveness group. In the AKI group, HR, Cre, and Lac decreased, while in the non-AKI group, HR decreased, but CVP and SV increased. There were differences between HR, Lac, and change rate of Lac (Lac%) after fluid resuscitation for the positive and negative fluid responsiveness groups. There was no statistical difference between the RRI values of each group before and after fluid resuscitation. The RRI values of the AKI group were higher than those of the non-AKI group, while the AKI group's RBF grades were lower than those of the non-AKI group. The change rate of RRI (RRI%) was higher in the AKI group than in the non-AKI group. Except for the negative fluid responsiveness group, the RBF grade of each group increased.

CONCLUSIONS

The approach of RBF classification based on Doppler ultrasound can be used to evaluate the systemic and renal perfusion of patients with severe sepsis before and after fluid resuscitation, while the RRI value cannot be used for evaluation. However, the RRI value can be used as a dynamic index for the evaluation of renal perfusion in patients with AKI.

[Experimental study on the effect of olfactory training on olfactory function in mice with olfactory dysfunction]

Objective: To observe the effect of olfactory training on mice with olfactory dysfunction induced by 3-methylindole (3-MI). Methods: Thirty-one male BALB/c mice were randomly divided into 3 groups by random digits table: control group (group A, n=10), olfactory dysfunction group (group B, n=10) and olfactory dysfunction+olfactory training group (group C, n=11). Mice in group B and group C were intraperitoneally injected with 150 mg/kg 3-MI to induce olfactory dysfunction model, while mice in group A were intraperitoneally injected with corn oil of the same volume. From the first day after injection, mice in group C were treated with 4 kinds of odors by inhalation, while mice in group B were treated with distilled water by inhalation, with 2 times/d, 30 min/time/kind of odor, and continuous training for 28 d. Group A was not treated. Buried food pellet tests were conducted before injection and at 7, 14, 21 and 28 days after injection, respectively. The olfactory epithelium was harvested for observation of the number of olfactory marker protein (OMP) and the thickness of olfactory epithelium on the 28th day after injection. SPSS 23.0 software was used for statistical analysis. Results: Before injection, all mice in each group had no olfactory dysfunction. At the 7th, 14th, 21st and 28th days after injection, the food finding time of mice in group C was shorter than that in group B, and the difference was statistically significant ((175.88±100.50) s vs (266.73±46.83) s, (132.00±84.62) s vs (264.10±48.50) s, (103.57±77.43) s vs (197.43±69.78) s, (67.79±32.54) s vs (176.63±61.06) s, all P<0.05), but food finding time of mice in group B and C was longer than that in group A (the food finding time of group A at the 7th, 14th, 21st and 28th days after injection was (27.13±5.36) s, (25.83±7.28) s, (23.13±2.72) s, (26.63±7.60) s, respectively, all P<0.05). At the 28th day after olfactory training, the number of OMP positive cells in group B and C were fewer than that in group A, and the difference was statistically significant ((108.00±28.19)/HP vs (288.22±84.06)/HP, (199.33±58.55)/HP vs (288.22±84.06)/HP, all P<0.05). The number of OMP positive cells in group C were higher than that in group B (P<0.05). The number of OMP positive cells had negative correlation with food finding time (r=-0.886, P<0.01). As for the thickness of the olfactory epithelium, the thickness of group B was thinner than that in group A and C, and the difference was statistically significant ((59.57±31.27) μm vs (114.55±40.70)μm vs (90.54±37.72) μm, all P<0.05). Conclusion: Olfactory training can accelerate the recovery of olfactory function in 3-MI-induced olfactory impaired mice.

The Abscopal Effect of Stereotactic Radiotherapy and Immunotherapy: Fool's Gold or El Dorado?

An 'abscopal' effect if often used to refer to distant tumour regression after localised irradiation. Since the first report of the abscopal effect in the 1950s, well-documented cases with radiotherapy alone are very rare. It is widely accepted that the immune response plays an important role in the abscopal effect, although the mechanism is still unclear. With the recent success of cancer immunotherapy, there is growing interest in combining immunotherapy with radiotherapy to boost abscopal response rates. Compared with conventional radiotherapy, stereotactic ablative radiotherapy (SABR) not only delivers ablative dose to the tumour, but may also induce robust immune responses. In this review we examine studies that combine SABR and immunotherapy. We review the preclinical rationale for SABR and immunotherapy combinations, the case for and against abscopal effects, and the current landscape of clinical trials.

[Exploration on developing the diagnosis and treatment guidelines for osteoarthritis in primary care of China]

At present, several clinical practice guidelines for osteoarthritis have been developed. Although contradictions about some recommendations are still in dispute, large number of clinical practice guidelines recommended core treatments, namely education, weight loss and exercise therapy. Thus, the diagnosis and treatment of primary osteoarthritis should focus on the above three treatments. However, we have to develop the clinical practice guidelines for osteoarthritis in primary hospital, based on the characteristics of osteoarthritis in China, the burden of disease, the health literacy of patients and the clinical decision-making of diagnosis and treatment of primary osteoarthritis in primary medical care.We suggest to formulate guidelines for the diagnosis and treatment of osteoarthritis in primary medical care to regulate primary interventions.

Intra-articular injection of mesenchymal stem cells in treating knee osteoarthritis: a systematic review of animal studies

PURPOSE

Mesenchymal stem cells (MSCs) injection has emerged as a novel treatment for knee osteoarthritis (KOA) but with inconsistent results in the experimental studies. Thus, the purpose of the present study is to evaluate the preclinical animal studies of MSCs injection for KOA and to determine the evidence for a role for MSCs in further clinical trials.

METHODS

A systematic search of KOA animal studies published through Aug 2017 was conducted using the PubMed, Embase and Web of science. Criteria for eligibility were animal studies assessing the therapeutic effects of MSCs intra-articular injection to animals with KOA. The methodological quality of included studies was assessed by the SYRCLE tool for assessing risk of bias in animal intervention studies. Descriptive synthesis was performed. Evidence quality was evaluated based on the Confidence in the Evidence from Reviews of Qualitative research (CERQual) tool.

RESULTS

Twenty-three KOA animal studies were eligible for inclusion. According to the SYRCLE's tool, all included studies had high risk of bias. Between-study heterogeneity was substantial. The included studies varied in terms of species, modeling methods, MSCs origin, treatment timing, injections frequency, transplantation type and dose of MSCs. The following outcomes, gross morphology, histological analysis, immunohistochemical analysis, radiological evaluation or behavior analysis, were reported in the primary studies. For all outcomes, the evidence quality was low or very low.

CONCLUSIONS

We do not have absolute confidence to recommend use MSCs injection for KOA clinical trials. Based on the internal and external validity of current animal studies, high quality experimental studies and efforts for effective translation from preclinical studies to clinical trials are still required.

[Progress in methodological characteristics of clinical practice guideline for osteoarthritis]

At present, several clinical practice guidelines for the treatment of osteoarthritis have been developed by institutes or societies. The ultimate purpose of developing clinical practice guidelines is to formulate the process in the treatment of osteoarthritis effectively. However, the methodologies used in developing clinical practice guidelines may place an influence on the transformation and application of that in treating osteoarthritis. The present study summarized the methodological features of individual clinical practice guideline and presented the tools for quality evaluation of clinical practice guideline. The limitations of current osteoarthritis guidelines of China are also indicated. The review article might help relevant institutions improve the quality in developing guide and clinical transformation.

Abstract OT2-02-02: A randomized, open-label, multicenter, phase 1b/2 study of eribulin mesylate in combination with PEGylated recombinant human hyaluronidase in patients with human epidermal growth factor receptor 2-negative, high-hyaluronan metastatic breast cancer

Eribulin (ERI), a non-taxane microtubule inhibitor, is approved for treatment in patients (pts) with advanced or metastatic breast cancer (MBC) who have received ≥1 (European Union) or ≥2 (United States) prior chemotherapy regimens for metastatic disease, including an anthracycline and taxane in either the adjuvant or metastatic setting. In a phase 2 study, ERI has demonstrated single-agent activity in first line treatment of pts with human epidermal growth factor receptor 2-negative (HER2−) MBC. Hyaluronan (HA) is a major component of the tumor microenvironment, specifically within the stroma, and high levels of HA are associated with disease progression. In HA-High, triple-negative breast cancer (TNBC) xenografts, the anti-tumor effect of ERI was enhanced by addition of PEGylated recombinant human hyaluronidase (PEGPH20). PEGPH20 is an engineered enzyme under investigation for use in combination with anticancer therapies in pts with tumors that accumulate HA. PEGPH20 acts by temporarily degrading HA to reduce tumor interstitial pressure and decompress blood vessels, thus increasing access of anticancer agents and immune cells to tumor sites. This randomized, open-label, multicenter, study of ERI in combination with PEGPH20 vs ERI alone was designed to evaluate safety and tolerability and efficacy in pts with HER2−, HA-High, MBC previously treated with 0–1 systemic (cytotoxic or targeted) anticancer therapy.

The trial was activated in June 2016 and will enroll approximately 96 pts (aged ≥18 yrs; n=6–18 in phase 1b; n=84 randomized to obtain 80 evaluable pts in phase 2).Pts with measurable disease of ≥1 lesion ≥10 mm in long-axis diameter (nonlymph nodes) or ≥15 mm in short-axis diameter (lymph nodes) with ECOG PS of 0 or 1 will be included. Pts will be excluded for having had adjuvant chemotherapy within the past 6 months, hormonal/biological therapy within the past 3 wks, or radiation or small molecule targeted therapy within the past 2 wks. Pts will also be excluded if they were previously treated with ERI or any hyaluronidase agent.

Phase 1b includes at least 1 initial safety run-in cohort in which 6 pts (any HA level) will receive PEGPH20 3 μg/kg intravenous (IV) on days −1 and 7 of a 21-day cycle, each dose followed approximately 24 (±4) hours later with ERI 1.4 mg/m2 IV on days 1 and 8. Dose-limiting toxicity (DLT) will be assessed in the first cycle.The primary endpoint in phase 1b is the recommended phase 2 dose (RP2D) of the ERI and PEGPH20 combination, defined as the maximum dose at which ≤1 pt experiences a DLT.Alternatively, modified dose levels will be evaluated in additional cohorts.

In phase 2, HA-High pts will be stratified by TNBC vs other HER2− status and randomized to receive RP2D combination treatment or ERI alone. Pts with clinical benefit will remain on ERI or both study drugs until unacceptable toxicity or disease progression. The primary endpoint in phase 2 is objective response rate. Secondary endpoints include progression-free survival and overall survival. Exploratory endpoints include clinical benefit rate, disease control rate, and duration of response.

Citation Format: Alvarez RH, Savulsky C, Almonte A, Xing D, Lokker N, Chondros D. A randomized, open-label, multicenter, phase 1b/2 study of eribulin mesylate in combination with PEGylated recombinant human hyaluronidase in patients with human epidermal growth factor receptor 2-negative, high-hyaluronan metastatic breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr OT2-02-02.

Estrogen alone or in combination with parathyroid hormone can decrease vertebral MEF2 and sclerostin expression and increase vertebral bone mass in ovariectomized rats

The study is about the regulatory effects of estrogen and parathyroid hormone (PTH) on sclerostin, a protein that inhibits the Wnt/β-catenin pathway. The results indicate that estrogen may down-regulate sclerostin expression and that estrogen displays synergistic action with PTH. These results provide a new perspective on the relationship between estrogen and bone.

PURPOSE

To investigate whether estrogen can down-regulate SOST and MEF2 (myocyte enhancer factor 2) expression and whether co-treatment with estrogen and PTH has a stronger effect on suppressing SOST than PTH applied alone in ovariectomized rats.

METHODS

Forty-three-month-old virgin female Sprague-Dawley (SD) rats were ovariectomized and divided into four groups (n = 10). Another ten age-matched rats received sham operations as controls. After allowing 8 weeks for the development of vertebral osteopenia, the rats were administered the drug intervention. For this intervention, the estrogen group was subcutaneously injected with 17β-estradiol at 25 μg/kg body weight, the PTH group was injected with 80 μg/kg synthetic human PTH (1-34), and the co-treatment group was concurrently treated with PTH and estrogen at the above dosage. The OVX group and sham group were treated with vehicle. The drug treatment was conducted for 12 weeks. After the lumbar spine bone mineral density (BMD) was measured, the rats were sacrificed, and the lumbar spine and blood were collected for qPCR, Western blot, immunohistochemistry and other tests.

RESULTS

Estrogen can down-regulate MEF2 and sclerostin expression, and co-treatment with estrogen and PTH has a stronger effect on suppressing MEF2 and SOST mRNA than PTH alone. The co-treatment group displayed slightly higher bone mass and biomechanical properties than the PTH group, but the differences were not significant.

CONCLUSIONS

Estrogen appears to be a regulator of sclerostin, and the effect may involve suppressing MEF2s. Combined treatment with PTH and estrogen is not more beneficial for vertebral bone mass and strength than treatment with PTH alone in ovariectomized rats.

Association between use of benzodiazepines and risk of fractures: a meta-analysis

Benzodiazepines (BZDs) are some of the most commonly prescribed drugs in the world. It has been shown that BZD use could be associated with increased fracture risk. However, studies on the use of BZDs and fracture risk have yielded inconsistent results. Results from the present meta-analysis show that BZD use is associated with a moderate and clinically significant increase in the risk of fractures.

INTRODUCTION

The relationship between the use of BZDs and fracture risk has been neither well identified nor summarized. This meta-analysis reports on the use of BZDs, especially short-acting BZDs, and their correlation with a moderate and clinically significant increase in fracture risk. This analysis will provide evidence for clinicians to consider fracture risk when prescribing BZDs among the elderly population. This study was conducted to determine whether people who take BZDs are at an increased fracture risk.

METHODS

A systematic search of studies published through January 2013 was conducted using MEDLINE, EMBASE, OVID, and ScienceDirect. Case-control and cohort studies that assessed the relationship between BZD use and the risk of fractures were identified. Literature searches, study selections, methodological assessments, and data mining were independently conducted by two reviewers. Disagreements were resolved by consensus. STATA 12.0 software was used for the meta-analysis. Random effects models were used for pooled analysis due to heterogeneity among the studies.

RESULTS

There were 25 studies, including 19 case-control studies and 6 cohort studies, that met the inclusion criteria. Overall, the results of the meta-analysis indicated that BZD use was associated with a significantly increased fracture risk (relative risk (RR) = 1.25; 95% confidence intervals (CI), 1.17-1.34; p < 0.001). Increased fracture risk associated with BZD use was observed in participants aged ≥65 years old (RR = 1.26; 95% CI, 1.15-1.38; p < 0.001). When only hip fractures were included as the outcome measure, the RR increased to 1.35. However, subgroup meta-analyses showed that there was no significant association between BZD use and fracture risk in Eastern countries (RR = 1.27; 95% CI, 0.76-2.14; p = 0.362) as well as between long-acting BZD use and risk of fractures (RR = 1.21; 95% CI, 0.95-1.54; p = 0.12). After accounting for publication bias, we observed that the overall association between BZD use and fracture risk to be slightly weaker (RR = 1.21; 95% CI, 1.13-1.30) but still significant.

CONCLUSION

The results of this meta-analysis demonstrate that the use of BZD, especially short-acting BZD, is associated with a moderate and clinically significant increase in fracture risk. However, large prospective studies that minimize selection bias are necessary to determine a more accurate fracture risk associated with BZD use.

Association between aspartic acid repeat polymorphism of the asporin gene and susceptibility to knee osteoarthritis: a genetic meta-analysis

OBJECTIVE

Knee osteoarthritis (KOA) is a common disease that is characterized by the degeneration of joint cartilage in the knee. Genetic factors have been implicated in KOA. Recently, several genetic studies have suggested that susceptibility to KOA is affected by the number of aspartic acid (D) residues in the amino-terminal of the asporin protein, but evidence remains conflicting. Therefore, the objective of the present meta-analysis was to investigate whether or not the D-repeat polymorphism is associated with susceptibility to KOA.

METHODS

A systematic search of all relevant studies published through Dec 2012 was conducted using the MEDLINE, EMBASE, OVID, and ScienceDirect. Allelic counts were evaluated for the D14 and D13 alleles respectively. The included studies were only assessed in the analysis of the following allele model: D14 allele vs others alleles combined, D13 allele vs others alleles combined, and D14 allele vs D13 allele.

RESULTS

Seven studies (eight comparisons) with 5515 total participants (2334 KOA patients and 3181 controls), which involved four Caucasian and four Asian populations, were eligible for inclusion. Meta-analysis was conducted for genotype D14 vs others combined, D13 vs others combined, and D14 vs D13. In the stratification based on ethnicity, studies were divided into Caucasian and Asian populations. We did not detect positive association between KOA and the D14 allele in Asian populations (OR = 1.527, 95% CI: 0.879-2.653) and in Caucasian populations (OR = 1.053, 95% CI: 0.905-1.225). There was also no positive association between susceptibility to KOA and D13 allele in Asian populations (OR = 0.950, 95% CI: 0.732-1.233) and in Caucasian populations (OR = 0.866, 95% CI: 0.723-1.037).

CONCLUSION

The present results suggest that the D-repeat of asporin gene (ASPN) may not be a major susceptibility locus in the Caucasian and Asian populations with KOA. Because of the limitations of the present meta-analysis, accurate conclusions could not be drawn based on the current evidence, and further studies with large sample size are required.

Shifted encoding strategy in retinal luminance adaptation: from firing rate to neural correlation

Neuronal responses to prolonged stimulation attenuate over time. Here, we ask a fundamental question: is adaptation a simple process for the neural system during which sustained input is ignored, or is it actually part of a strategy for the neural system to adjust its encoding properties dynamically? After simultaneously recording the activities of a group of bullfrog's retinal ganglion cells (dimming detectors) in response to sustained dimming stimulation, we applied a combination of information analysis approaches to explore the time-dependent nature of information encoding during the adaptation. We found that at the early stage of the adaptation, the stimulus information was mainly encoded in firing rates, whereas at the late stage of the adaptation, it was more encoded in neural correlations. Such a transition in encoding properties is not a simple consequence of the attenuation of neuronal firing rates, but rather involves an active change in the neural correlation strengths, suggesting that it is a strategy adopted by the neural system for functional purposes. Our results reveal that in encoding a prolonged stimulation, the neural system may utilize concerted, but less active, firings of neurons to encode information.

Open reduction and internal fixation versus external fixation for unstable distal radial fractures: a meta-analysis

PURPOSE

To compare the clinical outcomes of open reduction and internal fixation (ORIF) versus the ones of closed reduction and external fixation (EF) in the treatment of distal radial fractures.

METHODS

We performed a meta-analysis of randomized controlled trials that compared the clinical results of ORIF to EF in the treatment of distal radial fractures. A systemic retrieve from PubMed, EMBASE, OVID and Cochrane Collaboration CENTRAL database resulted in 11 studies with 824 patients. We thus performed data synthesis using RevMan (version 5.1).

RESULTS

Superior statistical differences were observed for DASH scores (at 3, 6 and 12 months follow-up) grip strength (at 3 months follow-up), volar tilt (at 12 months follow-up), flexion and supination (at 3 months follow-up), and extension (at 3 and 6 months follow-up) in ORIF patients group, compared with those in EF group. We also found a significantly higher risk of infection associated with EF. There was no significant difference in the incidence of malunion and median nerve dysfunction.

CONCLUSION

Regarding surgical fixation of unstable distal radius fractures, ORIF yields significantly better subjective outcome (DASH scores) the first year after operation, restoration of anatomic volar tilt, and forearm flexion and extension at the end of the follow-up period. However, EF results in higher incidence of infection compared to ORIF. ORIF is equal to EF for either grip strength, or range of motion of the injured wrist, or incidence of malunion or median nerve dysfunction at the end of the follow-up period.

LEVEL OF EVIDENCE

Level II. Therapeutic study.

The percutaneous compression plate versus the dynamic hip screw for treatment of intertrochanteric hip fractures: a systematic review and meta-analysis of comparative studies

BACKGROUND

The use of a percutaneous compression plate (PCCP) provides a minimally invasive technique for the fixation of stable intertrochanteric femoral fractures. It has several theoretically potential advantages over the dynamic hip screw (DHS) such as shorten incision and lower incidence of wound infection.

HYPOTHESIS

PCCP have several advantages than DHS, such as reduced blood loss, transfusion, mortality, shorter operative time, and lower incidence of complications. This systematic review and meta-analysis was performed to identify the clinical outcomes and safety of patients with stable intertrochanteric hip fractures operated on using PCCP compared with DHS.

MATERIALS AND METHODS

A systematic search of all studies published through April 2012 was conducted using the Medline, Embase, Sciencedirect, OVID and the Cochrane Central database. The randomized controlled trials (RCTs) and quasi-randomised control trials (qRCTs) that compared PCCP with DHS in treating adult patients with stable intertrochanteric hip fractures and provided data on safety and clinical effects were identified. Demographic characteristics, adverse events and clinical outcomes were manually extracted from all of the selected studies.

RESULTS

Nine studies encompassing 914 patients met the inclusion criteria. Overall, the result of meta-analysis indicated that over DHS, PCCP allowed significantly shorter operative time, reduced blood loss as well as transfusion, diminished incidence of cardiovascular events. However, there were no significant differences in length of hospitalization, rate of walking without help, early mortality and other complications.

DISCUSSION

Significant differences favoring PCCP were found with regard to operative time, blood loss, transfusion and lower incidence of cardiovascular events. However, owing to the limitations of this systematic review, future RCTs are still needed to confirm this data and the clinical efficiency of PCCP.

LEVEL OF EVIDENCE

Level II: low-powered prospective randomized trial.

Local circuit inhibition in the cerebral cortex as the source of gain control and untuned suppression

Theoretical considerations have led to the concept that the cerebral cortex is operating in a balanced state in which synaptic excitation is approximately balanced by synaptic inhibition from the local cortical circuit. This paper is about the functional consequences of the balanced state in sensory cortex. One consequence is gain control: there is experimental evidence and theoretical support for the idea that local circuit inhibition acts as a local automatic gain control throughout the cortex. Second, inhibition increases cortical feature selectivity: many studies of different sensory cortical areas have reported that suppressive mechanisms contribute to feature selectivity. Synaptic inhibition from the local microcircuit should be untuned (or broadly tuned) for stimulus features because of the microarchitecture of the cortical microcircuit. Untuned inhibition probably is the source of Untuned Suppression that enhances feature selectivity. We studied inhibition's function in our experiments, guided by a neuronal network model, on orientation selectivity in the primary visual cortex, V1, of the Macaque monkey. Our results revealed that Untuned Suppression, generated by local circuit inhibition, is crucial for the generation of highly orientation-selective cells in V1 cortex.

Detection and widespread distribution of sodium channel alleles characteristic of insecticide resistance in Culex pipiens complex mosquitoes in China

Culex pipiens complex mosquitoes are widely distributed throughout China and are known to be important disease vectors. Two pyrethroid resistance associated mutations have been identified in Cx. pipiens complex (Diptera: Culicidae), but there is little information on the diversity and distribution of kdr alleles in pyrethroid resistance in Cx. pipiens complex mosquitoes in China. In the present study, we report on a modified three tube allele-specific (AS)-PCR method for detecting the 1014F and 1014S alleles. The new technique was applied to identify the distribution of the two alleles in natural Cx. pipiens complex populations in China. The results confirmed that the new method is both sensitive and specific. The 1014F allele was found in all 14 of the field populations tested (frequency ranged from 6.8 to 76.2%) and the 1014S allele was found in almost two-thirds (frequency from 2.4 to 28.6%), indicating that the genotypes known to be associated with pyrethroid resistance are widespread in China. The resistance-associated alleles were more common in southern Chinese sampling sites than in northern sites. The coexistence of the two resistant mutations in individual mosquitoes was also observed in five of the field populations. Two alternative mutations within the L1014 codon were identified in Culex pipiens molestus Forskal, 1775, including a non-synonymous mutation resulting in a 1014C substitution.

Satisfaction with continuous glucose monitoring in adults and youths with Type 1 diabetes

AIMS

To describe satisfaction with continuous glucose monitoring in Type 1 diabetes; to correlate continuous glucose monitoring satisfaction scores with usage; and to identify common themes in perceived benefits and barriers of monitoring reported by adults, youths and the parents of youths in the Juvenile Diabetes Research Foundation continuous glucose monitoring trials.

METHODS

The Continuous Glucose Monitoring Satisfaction Scale questionnaire was completed after 6 months of monitoring. Participants also answered open-ended queries of positive and negative attributes of continuous glucose monitoring.

RESULTS

More frequent monitoring was associated with higher satisfaction for adults (n = 224), youths (n = 208) and parents of youths (n = 192) (all P < 0.001) in both the 'benefits' and 'hassles' sub-scales of the Continuous Glucose Monitoring Satisfaction Scale, but the greatest differences between the two groups involved scores on hassle items. Common barriers to monitoring use included insertion pain, system alarms and body issues; while common benefits included glucose trend data, opportunities to self-correct out-of-range glucose levels and to detect hypoglycaemia.

CONCLUSIONS

As frequent use of continuous glucose monitoring is associated with improved glycaemic control without increased hypoglycaemia it is important to overcome barriers, reinforce benefits and set realistic expectations for this technology in order to promote its more consistent and frequent use in individuals with Type 1 diabetes.

Effect of water deficit on biomass production and accumulation of secondary metabolites in roots of Glycyrrhiza uralensis

Two-year-old seedlings of licorice plant (Glycyrrhiza uralensis Fisch) were exposed to three degrees of water deficit, namely weak (60-70%), moderate (40-50%), and strong (20-30%) relative water content in soil, whereas control plants were grown in soil with 80-90% water content. Moderate and strong water deficit decreased the net photosynthetic rate, stomatal conductance, and biomass production. Water use efficiency and the root-to-shoot ratio increased significantly in response to water deficit, indicating a high tolerance to drought. Weak water deficit did not decrease root biomass production, but significantly increased the production of glycyrrhizic acid (by 89%) and liquiritin (by 125%) in the roots. Therefore, a weak water deficit can increase the yield of root medical compounds without negative effect on root growth.

Evaluation of fourth international standard for whole cell pertussis vaccine

Whole cell pertussis vaccine is still widely used in many countries. An International Standard is needed for its potency control. The Third International Standard for Pertussis Vaccine was prepared about 40 years ago and its replacement was recommended by the Expert Committee for Biological Standardisation (ECBS) of the WHO. Material in ampoules coded 94/532 was prepared as a candidate replacement and has been evaluated in international collaborative studies which consisted of two parts. The first part, to assess the suitability of the candidate standard by comparing it with the Second International Standard for Pertussis Vaccine (IS2) involved 14 laboratories in 11 countries. The second part to compare the candidate standard with the Third International Standard for Pertussis Vaccine (IS3) involved 16 laboratories in 14 countries. Since 1995 various other studies have included the international standards and the results of these are also considered in assessing likely continuity of the IU for potency of whole cell pertussis vaccine. The preparation in ampoules coded 94/532 was adopted by the WHO ECBS in October 2006 as the 4th International Standard for whole cell pertussis vaccine and assigned an activity of 40 IU per ampoule on the basis of the studies reported here.

Collaborative study for the standardisation of the histamine sensitizing test in mice and the CHO cell-based assay for the residual toxicity testing of acellular pertussis vaccines

The European Pharmacopoeia (Ph. Eur.) and the World Health Organisation (WHO) require the performance of extensive quality and safety control testing before the release on the market of vaccine products for human use. Safety testing with regard to residual pertussis toxin (PT) in acellular pertussis combination vaccines is performed through assessment of fatal sensitisation of mice to histamine challenge by the vaccine product under test. Currently, use of different in-house procedures and no requirement for the inclusion of a standard reference in each assay render comparisons of results obtained for identical vaccine batches between different control laboratories very difficult. At the initiative of the European Directorate for the Quality of Medicines and HealthCare (EDQM), an international collaborative study was organised for the standardization of the Histamine Sensitizing Test (HIST) in mice and the Chinese Hamster Ovary (CHO)-cell-based assay (performed at the bulk product level) for the residual toxicity testing of acellular pertussis vaccines or acellular pertussis-based combination vaccines. The study was run under the aegis of the Biological Standardisation Programme, jointly supported by the Council of Europe and the European Commission under the project code BSP076. Ten (10) laboratories participated in the study and were requested to perform 3 independent Histamine Sensitizing Tests in mice and to report results of the lethal end-point measurement as prescribed by the Ph. Eur. monographs. Some of them also reported data from an in-house validated CHO-cell-based assay. In addition, some of the laboratories reported concomitantly data obtained by measurement of the drop in temperature induced after the histamine challenge, a method currently under investigation to be added as an alternative end-point for the HIST in the Ph. Eur. monographs for acellular pertussis-based combination vaccines in order to alleviate animal suffering (in application of the 3Rs principle). Based on the results of the collaborative study, a potency of 7500 IU/vial (International Units per vial) was assigned to the current Ph. Eur. Biological Reference Preparation (BRP) for PT. The results of the study also show that 1) intra- and inter-laboratory variations can be improved by the use of a validated standard operating procedure; 2) inclusion in each assay of a standard reference sample, calibrated in IU, can increase comparability of results among laboratories and thus help to reduce repeat testing; 3) a correlation between mortality data and temperature data was observed although, due to the limited number of data sets and the lack of a common method for the temperature end-point, further investigation of this point is required; 4) the CHO-cell-based assay did not yield comparable results and further standardisation of the assay procedure may be investigated in a follow-up project.