Emerging technologies for profiling extracellular vesicle heterogeneity

Extracellular vesicles (EVs) are membrane-bound vesicles secreted by most cell types and exist in virtually all bodily fluids. They carry on a wealth of proteomic and genetic information including proteins, lipids, miRNAs, mRNA, non-coding RNA and other molecules from parental cells. Increasing evidence shows that within populations of EVs, their biogenesis, physical characteristics (e.g. size, density, morphology) and cargos (e.g. protein, lipid content, nucleic acids) may vary substantially, which accordingly change their biological properties. To fully exploit the potential of EVs, it requires qualified methods to profile EV heterogeneity. In this review, we survey recent approaches for EV isolation with innovative discoveries in heterogeneity. The main challenges in EV heterogeneity research are identified, and the roles of single cell EV profiling and single EV imaging are highlighted. We further discuss promising opportunities for resolving the underlying complexity of EV heterogeneity.

Endosperm enrichment and physicochemical properties of superior and inferior grain starch in super hybrid rice

A significant asynchronous phenomenon exists in super hybrid rice because of the differences in spike and spikelet positions, which affect the accumulation and properties of starch. However, little is known about the endosperm enrichment and physicochemical properties of starch in superior and inferior grains in super hybrid rice. Rice YY2640 was selected as study material to investigate the enrichment and physicochemical properties of starch in superior and inferior grains in super rice using semi-thin sections, X-ray diffraction and related technologies. Superior grain filling was a continuous process, whereas inferior grain only started 8-10 days after anthesis. The order of starch accumulation starts in the central endosperm, then in the endosperm of the proximal vascular bundle and finally in the aleurone layer. Compared with the inferior grains, the superior grains have a higher 1000-grain weight, apparent amylose content, total starch content, average starch granule size, relative crystallinity, solubility and a resonance peak ratio at 1022/995 cm^-1 , whereas the swelling power and ratio of the resonance peak at 1045/1022 cm^-1 were lower. The final degree of hydrolysis of HCl, AAG and PPA of the superior grains were significantly lower than those of the inferior grains. The findings indicate that the different physicochemical properties of starch were mainly related to the development order of superior and inferior grains and the spatial enrichment of starch.

Optical Nanomaterials and Enabling Technologies for High-Security-Level Anticounterfeiting

Optical nanomaterials have been widely used in anticounterfeiting applications. There have been significant developments powered by recent advances in material science, printing technologies, and the availability of smartphone-based decoding technology. Recent progress in this field is surveyed, including the availability of optical reflection, absorption, scattering, and luminescent nanoparticles. It is demonstrated that advances in the design and synthesis of lanthanide-doped upconversion nanoparticles will lead to the next generation of anticounterfeiting technologies. Their tunable optical properties and optical responses to a range of external stimuli allow high-security level information encoding. Challenges in the scale-up synthesis of nanomaterials, engineering of assessorial devices for smart-phone-based decryption, and alignment to the potential markets which will lead to new directions for research, are discussed.

Genomic origin and EGFR-TKI treatments of pulmonary adenosquamous carcinoma

BACKGROUND

Adenosquamous carcinoma (ASC) of the lung is a heterogeneous disease that is composed of both adenocarcinoma components (ACC) and squamous cell carcinoma components (SCCC). Their genomic profile, genetic origin, and clinical management remain controversial.

PATIENTS AND METHODS

Resected ASC and metastatic tumor in regional lymph nodes (LNs) were collected. The ACC and SCCC were separated by microdissection of primary tumor. The 1021 cancer-related genes were evaluated by next-generation sequencing independently in ACC and SCCC and LNs. Shared and private alterations in the two components were investigated. In addition, genomic profiles of independent cohorts of adenocarcinomas and squamous cell carcinomas were examined for comparison. We have also carried out a retrospective study of ASCs with known EGFR mutation status from 11 hospitals in China for their clinical outcomes.

RESULTS

The most frequent alterations in 28 surgically resected ASCs include EGFR (79%), TP53 (68%), MAP3K1 (14%) mutations, EGFR amplifications (32%), and MDM2 amplifications (18%). Twenty-seven patients (96%) had shared variations between ACC and SCCC, and pure SCCC metastases were not found in metastatic LNs among these patients. Only one patient with geographically separated ACC and SCCC had no shared mutations. Inter-component heterogeneity was a common genetic event of ACC and SCCC. The genomic profile of ASC was similar to that of 170 adenocarcinomas, but different from that of 62 squamous cell carcinomas. The incidence of EGFR mutations in the retrospective analysis of 517 ASCs was 51.8%. Among the 129 EGFR-positive patients who received EGFR-TKIs, the objective response rate was 56.6% and the median progression-free survival was 10.1 months (95% confidence interval: 9.0-11.2).

CONCLUSIONS

The ACC and SCCC share a monoclonal origin, a majority with genetically inter-component heterogeneity. ASC may represent a subtype of adenocarcinoma with EGFR mutation being the most common genomic anomaly and sharing similar efficacy to EGFR TKI.

Organic trace minerals improve eggshell quality by improving the eggshell ultrastructure of laying hens during the late laying period

The objective of this study was to investigate the effects of low inclusion levels of organic trace minerals (iron, copper, manganese, and zinc) on performance, eggshell quality, serum hormone levels, and enzyme activities of laying hens during the late laying period. A total of 405 healthy hens (HY-Line White, 50-week-old) were randomly divided into 3 treatments, with 9 replications per treatment and 15 birds per replication. The dietary treatments included a basal diet supplemented with inorganic trace minerals at commercial levels (CON), a basal diet supplemented with inorganic trace minerals at 1/3 commercial levels (ITM), and a basal diet supplemented with proteinated trace minerals at 1/3 commercial levels (TRT). The trial lasted 56 D (8 wk). Compared with the CON group, the ITM group showed decrease in (P < 0.05) egg production, eggshell strength, eggshell palisade layer, palisade layer ratio, serum estrogen, luteinizing hormone, glycosaminoglycan concentration, and carbonic anhydrase activity and increase in (P < 0.05) egg loss and mammillary layer ratio. However, the TRT group almost kept all the indices close to the CON group (P > 0.05). Furthermore, hens fed with low inclusion levels of organic trace minerals had smaller mammillary knobs (P < 0.05) than those in the CON and ITM groups. In conclusion, hens fed with low inclusion levels of proteinated trace minerals had better performance and eggshell strength than those fed with identical levels of inorganic compounds; organic trace minerals improved eggshell quality by improving the eggshell ultrastructure of laying hens during the late laying period.

Gradient-sized control of tumor spheroids on a single chip

Multicellular tumor spheroids are attracting more attention as a physiologically relevant in vitro tumor model for biomedical research. The size of spheroids is one of the critical parameters related to drug penetration and cellular responses. It remains challenging to generate a large number of gradient-sized spheroids in one culture vessel. Here, a liquid-dome method was used to simultaneously produce more than 200 gradient-sized spheroids on an agarose chip. Surface tension effect was used to modulate the liquid spatial distribution and achieve a range of spheroid sizes. MCF-7 cells formed multiple spheroids on the chips for concept validation. It showed that different configurations of the liquid domes exhibited different levels of size control. Relative to the smallest spheroids in the configuration, hemispheric and square domes produced spheroids up to 3.4 and 12.8-fold larger in area, respectively. In addition, the co-culture of MCF-7 and fibroblasts helped to elucidate the tendency of fibroblasts towards the spheroid center. Other size-dependent behaviors were profiled; larger spheroids behaved differently from smaller spheroids in terms of spheroid growth, drug penetration and cellular responses. This method breaks the boundary between the preparation of gradient-sized spheroids and significant time/labour demand. It can be useful for drug screening and in vitro tumor modelling.

P5717Risk of QTC interval prolongation among cancer patients treated with tyrosine kinase inhibitors

Objective

QTc interval prolongation can lead to life-threatening complications such as torsade de pointes (TdP), ventricular tachycardia (VT), and sudden cardiac death (SCD). It can occur with various tyrosine kinase inhibitors (TKIs) but comparative analyses on the incidence and complication rates are scarce. We thus conducted a comprehensive analysis of TKI use and QTc prolongation in clinical practice.

Methods

We retrospectively reviewed the electronic medical records of all cancer patients who were treated with TKI between 01/2005 and 12/2018 at our institution. QTc prolongation was defined as a QTc ≥450 ms or 460 ms among male or female patients, respectively. For each type of TKIs, we determined the administration rate and incidence of QTc interval prolongation. We also studied the frequency of QTc prolongation ≥500 ms, the rate of increase of the QTc interval by ≥60 ms, and the development of complications (VT, TdP, and SCD).

Results

In the present study, we analyzed the data of 685 cancer patients (431 male and 254 female), including 299 patients with RCC, 188 with chronic leukemia, 55 with acute leukemia, 65 with thyroid cancer, 48 with lung cancer and 39 with GIST. These patients received 902 TKI administrations and QTc prolongation was reported in 1/3 of these (289 administrations). The highest frequency was seen with imatinib, nilotinib, and dasatinib (30, 40 and 50%). Among cases of QTc prolongation, a QTc interval ≥500 ms was documented in 53 (18.3%) and QTc progression ≥60 ms in 72 (25%). Complications were found in 14 cases (5%) including VT in 9, TdP in 2 and SCD in 3 administrations. Table 1 demonstrates the findings for each TKI.

Findings for TKIs in all patients Total Prolonged QTc QTc ≥500 QTc progression ≥60 VT SCD TdP Imatinib 165 54 13 10 2 Nilotinib 75 33 8 19 Dasatinib 115 58 10 16 2 1 Sunitinib 134 31 1 2 1 1 Pazopanib 165 36 5 6 2 1 Others 248 77 16 18 2 1 1

Conclusion

The current findings suggest that TKI therapy leads to QTc prolongation in 1/3 of patients on average and most commonly with the Bcr-Abl TKIs, imatinib, nilotinib, and dasatinib. While SCD is rare (1%) it can still evolve and in 5% of all QTc prolongations with TKIs are potentially life-threatening. These data support recommendations for serial ECGs in cancer patients undergoing TKI therapy.

Acknowledgement/Funding

None

P2601Trans-catheter or surgical mitral valve procedure versus conservative treatment in heart failure patients with preserved ejection fraction

Background

Secondary mitral regurgitation (SMR) impacts outcomes in heart failure with reduced ejection fraction (HFrEF) but whether it is a specific therapeutic target in heart failure patients with preserved ejection fraction (HFpEF) is less clear.

Purpose

The aims of this study were to investigate whether surgical or trans-catheter intervention reduces SMR and improves outcomes compared to optimal medical therapy in HFpEF patients.

Methods

We retrospectively identified 120 HFpEF patients with moderate-to-severe or greater SMR from January 1, 2007, until December 31, 2017. Moderate-to-severe SMR was defined as an effective regurgitant orifice area of >0.3cm2, and/or a regurgitation volume of >45ml per beat. Those with primary mitral regurgitation, endocarditis, HFrEF, hypertrophic cardiomyopathy, congenital heart disease, and history of valve intervention were excluded. All-cause mortality was analyzed and correlated to clinical and echocardiographic characteristics. Amongst the 120 patients, 36 received surgical or trans-catheter procedure in addition to medical therapy (procedure group) and 84 patients received optimal medical therapy only (conservative treatment group). The median follow-up period was 864 (15–3553) days.

Results

Patients in the procedure group were younger (75±8 vs 81±10, P=0.0002) and with fewer comorbidities (Charlson Comorbidity Index 7.0±2.4 vs 8.0±2.0, P=0.022) compared to the conservative treatment group. In addition, the procedure group had larger left ventricular end-diastolic diameters and higher SMR volume at baseline. During follow-up, SMR decreased by ≥2 grades in 75% of patients (27/36) in the procedure group compared to 20% of patients (12/60) in the conservative treatment group. After adjusting for age and comorbidities, the procedure group showed better overall survival compared to the conservative treatment group (HR 0.37; 95% CI 0.17–0.80; P=0.011). On multivariate analysis for the different groups (procedure group vs. conservative treatment group) (HR 0.40; 95% CI 0.17–0.91; P=0.019), increasing Charlson Comorbidity Index (HR 1.16; 95% CI 1.02–1.32; P=0.028) and average mitral E/e' ratio (HR 1.06; 95% CI 1.01–1.11; P=0.031) were independent predictors of increased all-cause mortality.

Kaplan-Meier Survival Curve

Conclusion

Among heart failure patients with preserved ejection fraction and moderate-to-severe or severe SMR, surgical or trans-catheter mitral-valve repair or replacement resulted in lower all-cause mortality compared to conservative treatment after 9 years of follow-up.

Neuroimaging correlates of language network impairment and reorganization in temporal lobe epilepsy

Advanced, noninvasive imaging has revolutionized our understanding of language networks in the brain and is reshaping our approach to the presurgical evaluation of patients with epilepsy. Functional magnetic resonance imaging (fMRI) has had the greatest impact, unveiling the complexity of language organization and reorganization in patients with epilepsy both pre- and postoperatively, while volumetric MRI and diffusion tensor imaging have led to a greater appreciation of structural and microstructural correlates of language dysfunction in different epilepsy syndromes. In this article, we review recent literature describing how unimodal and multimodal imaging has advanced our knowledge of language networks and their plasticity in epilepsy, with a focus on the most frequently studied epilepsy syndrome in adults, temporal lobe epilepsy (TLE). We also describe how new analytic techniques (i.e., graph theory) are leading to a refined characterization of abnormal brain connectivity, and how subject-specific imaging profiles combined with clinical data may enhance the prediction of both seizure and language outcomes following surgical interventions.

[A mini-incision on the anterior hip for pediatric femur neck fractures of type Delbet Ⅱ]

Objective: To investigate the early clinical outcomes of hip anterior short incision and open reduction and internal fixation for the treatment of children with Delbet Ⅱ femoral neck fracture. Methods: A retrospective analysis of 12 children with DelbetⅡ femoral neck fractures was performed with the anterior short incision approach at Department of Pediatric Orthopaedic, Children's Hospital, Nanjing Medical University from January 2014 to August 2016. There were 7 males and 5 females including 8 cases at left side and 4 cases at right side,aged (11.5±0.8) years (range: 8-14 years).Patients underwent surgery in (12.0±0.9) hours (range: 6-20 hours) after the injury. Displaced fractures were treated by open reduction if closed reduction failed.The surgical incision was performed with the anterior inferior iliac spine centered on, extending along the groin crease, and the length was 3 to 4 cm. The interval between the sartorius and the tensor fascia latae was applied, and the direct and indirect head of rectus femoris were resected to visualize the hip joint capsule. T-shaped incision was made in the capsule. After the reduction was obtained, two or three compression canulated screws were used to fix the fracture site. The healing time, complications and corresponding record outcome by X-ray and clinical examination were recorded. At the latest follow-up,the results were analyzed using the Ratliff criteria and clinical outcomes were assessed by pain, restrictive hip movement, normal activity or the avoidance of games, and the femoral neck in the radiograph. Results: Twelve patients had been followed-up for (30.0±4.1)months(range: 24-36 months). X-ray showed the fractures' healing time was (8.0±0.4) weeks(range: 7-9 weeks). Ten of the 12 fractures healed after one operation and were associated with no evidence of osteonecrosis of the femoral head. One case occurred premature physeal closure. There were no cases with fracture relocation, coaxvara, delayed union and nonunion or any significant postoperative complications. There was no infection, flexible internal fixation or ruptures. According to Ratliff grade, 9 cases of 12 patients were fine and 3 cases was acceptable. Conclusions: Satisfactory short-term effects can be achieved by a mini-incision on the anterior hip for Delbet Ⅱ pediatric femur neck fractures. The anterior incision has the advantage of less trauma, smaller incision scar, better fracture reduction and fixation, and less wound complications.

Laparoscopic vs open resection of pT4 colon cancer: a propensity score analysis of 94 patients

AIM

Our aim was to compare short- and long-term oncological outcomes between laparoscopic and open colectomy in T4 colon cancer.

METHODS

We retrospectively analysed oncological outcomes of 94 patients who underwent surgery between December 2010 and December 2016 for pT4 colon cancer, with propensity score matching. All patients were treated with curative intent, by either laparoscopic or open en bloc resection.

RESULTS

The conversion rate in the laparoscopic group was 17.0%. Blood loss, time to flatus and postoperative hospitalization were significantly less in the laparoscopic group. Postoperative morbidity and mortality within 30 days did not significantly differ between the two groups. R0 resection rates and lymph node harvests were similar between the two groups. At 5 years, laparoscopic outcomes were not inferior to open outcomes (overall survival 56.8% vs 50.2%, P = 0.250; disease-free survival 59.7% vs 41.7%, P = 0.06).

CONCLUSION

The laparoscopic approach is safe and feasible for pathologically confirmed T4 colon cancer. It results in a faster postoperative recovery.

Turbulence generation from a stochastic wavelet model

This research presents a new turbulence generation method based on stochastic wavelets and tests various properties of the generated turbulence field in both the homogeneous and inhomogeneous cases. Numerical results indicate that turbulence fields can be generated with much smaller bases in comparison to synthetic Fourier methods while maintaining comparable accuracy. Adaptive generation of inhomogeneous turbulence is achieved by a scale reduction algorithm, which greatly reduces the computation cost and practically introduces no error. The generating formula issued in this research could be adjusted to generate fully inhomogeneous and anisotropic turbulence with given RANS data under divergence-free constraint, which was not achieved previously in similar research. Numerical examples shows that the generated homogeneous and inhomogeneous turbulence are in good agreement with the input data and theoretical results.

[Complications of 2 133 cases of pediatric long bone fracture undergoing elastic stable intramedullary nailing in a single medical center]

Objective: To summarize the clinical data of elastic stable intramedullary nailing(ESIN) in the treatment of long bone fracture of children in a single medical center, and to analyze the problems occurred after the ESIN surgery and corresponding solutions. Methods: A retrospective analysis was conducted regarding the clinical data of 2 133 pediatric long bone fractures conforming to inclusion and exclusion criteria from June, 2005 to December, 2017 in Department of Orthopedics, Children's Hospital of Nanjing Medical University.There were 1 191 boys and 942 girls, aged from 23 months to 14 years with mean age of (5.7 ± 3.1)years.There were 1 866 cases treated with closed reduction with ESIN, while 267 cases were treated with small incision assisted reduction with ESIN.Postoperative problems have been statistically analyzed. Results: There were altogether 2 133 children, including 603 cases of femur, 311 cases of tibia, 8 cases of fibula, 219 cases of humerus, and 992 cases of ulna/radius.The postoperative complications mainly consist of 62 cases of needle tail irritation reaction, 21 cases of misalignments of fracture alignment, 11 cases of intramedullary nail deformity or angular deformity, 7 cases of limb shortening, 14 cases of limited joint activity, 4 cases of nerve injury, 2 cases of tendon injury, 14 cases of difficult nail removal, 4 cases of cortical cleavage, 8 cases of delayed union, 1 case of nonunion, 6 cases of varus/valgus deformity, 5 cases of epiphyseal injury, 6 cases of ESIN exposure, and 2 cases of metal debris of ESIN' end. Conclusions: The complications of treatment for children with long bone fractures by ESIN cannot be ignored.To master the important biomechanical properties, to get familiar with the local anatomy and to avoid obvious technical errors can reduce the occurrence of postoperative complications.

Anisotropic functionalization of upconversion nanoparticles

Despite significant advances toward accurate tuning of the size and shape of colloidal nanoparticles, the precise control of the surface chemistry thereof remains a grand challenge. It is desirable to conjugate functional bio-molecules onto the selected facets of nanoparticles owing to the versatile capabilities rendered by the molecules. We report here facet-selective conjugation of DNA molecules onto upconversion nanoparticles via ligand competition reaction. Different binding strengths of phosphodiester bonds and phosphate groups on DNA and the surfactant molecules allow one to create heterogeneous bio-chemistry surface for upconversion nanoparticles. The tailored surface properties lead to the formation of distinct self-assembly structures. Our findings provide insight into the interactions between biomolecules and nanoparticles, unveiling the potential of using nanoparticles as fundamental building blocks for creating self-assembled nano-architectures.

DNA-mediated anisotropic silica coating of upconversion nanoparticles

We report a facile approach of using DNA molecules as switches to selectively activate silica coating onto specific facets of upconversion nanoparticles.

High performance composites of spinel LiMn2O4/3DG for lithium ion batteries

A highly crystalline nanosized spinel LiMn₂O₄/3DG composite cathode material for high rate lithium ion batteries was successfully prepared by mixing spinel LiMn₂O₄ particles with reduced graphene oxide (3DG). Spinel LiMn₂O₄ and reduced three-dimensional graphene oxide were synthesized using a hydrothermal method and freeze-drying technology, respectively. The structure, morphology and electrochemical performance of the synthesized materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge–discharge techniques. The results showed that the LiMn₂O₄/3DG composites exhibited excellent rate capability and stable cycling performance. The discharge capacity was 131 mA h g⁻¹ and the capacity remains at 89.3% after 100 cycles at a 0.5 C rate, while the discharge capacity was 90 mA h g⁻¹ at 10 C. Compared with spinel LiMn₂O₄ materials, the LiMn₂O₄/3DG composites showed obvious improvement in electrochemical performance.

3DG/LiMn₂O₄ composites exhibit a high specific capacity and excellent rate performance.

Encoding Microreactors with Droplet Chains in Microfluidics

Droplet-based high throughput biomolecular screening and combinatorial synthesis entail a viable indexing strategy to be developed for the identification of each microreactor. Here, we propose a novel indexing scheme based on the generation of droplet sequences on demand to form unique encoding droplet chains in fluidic networks. These codes are represented by multiunit and multilevel droplets packages, with each code unit possessing several distinct signal levels, potentially allowing large encoding capacity. For proof of concept, we use magnetic nanoparticles as the encoding material and a giant magnetoresistance (GMR) sensor-based active sorting system supplemented with an optical detector to generate and decode the sequence of one exemplar sample droplet reactor and a 4-unit quaternary magnetic code. The indexing capacity offered by 4-unit multilevel codes with this indexing strategy is estimated to exceed 10⁴, which holds great promise for large-scale droplet-based screening and synthesis.

External Quality Assessment for Rubella Virus RNA Detection Using Armored RNA in China

BACKGROUND

Although tremendous efforts have been made to reduce rubella incidence, there are still 300 new cases of congenital rubella syndrome daily; thus, rubella infections remain one of the leading causes of preventable congenital birth defects. An effective surveillance system, which could be achieved and maintained by using an external quality assessment program, is critical for prevention and control of this disease.

METHODS

Armored RNAs, which are noninfectious and RNase-resistant, were used for encapsulation of the E1 gene of rubella virus and for preparation of a 10-specimen panel for external quality assessment. Thirty-two laboratories across mainland China that used nucleic acid tests for rubella virus RNA detection were included in the external quality assessment program organized by the National Center for Clinical Laboratories of China.

RESULTS

Different kinds of commercial kits were used by the laboratories for nucleic acid extraction and TaqMan real-time reverse-transcription PCR for rubella virus RNA detection; 99.2% sensitivity and 100% specificity were achieved in this external quality assessment program.

CONCLUSIONS

Most of the participating laboratories obtained accurate results for rubella nucleic acid tests, thereby achieving the quality required for regional rubella and congenital rubella syndrome elimination.

The immunoproteasome: An old player with a novel and emerging role in alloimmunity

Modern treatment strategies for the maintenance of allograft acceptance frequently target ubiquitously-expressed pathways, leading to significant side-effects and poor long-term allograft outcomes. Constitutive proteasome inhibitors, which have recently been introduced for the treatment of antibody-mediated rejection, target the ubiquitously-expressed proteasome. To limit off-target effects and serious mechanism-based toxicity, however, these inhibitors are administered intermittently and suboptimally. Immunoproteasomes, which are an inducible subset of proteasomes enriched in immune cells, replace constitutive proteasomes after cell exposure to proinflammatory cytokines such as interferon-γ. While immunoproteasomes were first described as processors of antigen for presentation by major histocompatibility complex molecules, recent findings point to its broader biological roles. These vary from activating different subsets of the immune system, by controlling transcriptional activators and downstream cytokines, to affecting their differentiation and survival. These emerging roles of the immunoproteasome in activated immune cells have made it a rational candidate for the targeted treatment of immune-mediated diseases. Preclinical studies have established its role in maintaining allograft acceptance without significant short- or long-term toxicity. This review provides a brief background of the immunoproteasome and outlines its role in immunological pathways and its potential in alloimmunity.

Canine GM2-Gangliosidosis Sandhoff Disease Associated with a 3-Base Pair Deletion in the HEXB Gene

BACKGROUND

GM2-gangliosidosis is a fatal neurodegenerative lysosomal storage disease (LSD) caused by deficiency of either β-hexosaminidase A (Hex-A) and β-hexosaminidase B (Hex-B) together, or the GM2 activator protein. Clinical signs can be variable and are not pathognomonic for the specific, causal deficiency.

OBJECTIVES

To characterize the phenotype and genotype of GM2-gangliosidosis disease in an affected dog.

ANIMALS

One affected Shiba Inu and a clinically healthy dog.

METHODS

Clinical and neurologic evaluation, brain magnetic resonance imaging (MRI), assays of lysosomal enzyme activities, and sequencing of all coding regions of HEXA, HEXB, and GM2A genes.

RESULTS

A 14-month-old, female Shiba Inu presented with clinical signs resembling GM2-gangliosidosis in humans and GM1-gangliosidosis in the Shiba Inu. Magnetic resonance imaging (MRI) of the dog's brain indicated neurodegenerative disease, and evaluation of cerebrospinal fluid (CSF) identified storage granules in leukocytes. Lysosomal enzyme assays of plasma and leukocytes showed deficiencies of Hex-A and Hex-B activities in both tissues. Genetic analysis identified a homozygous, 3-base pair deletion in the HEXB gene (c.618-620delCCT).

CONCLUSIONS AND CLINICAL IMPORTANCE

Clinical, biochemical, and molecular features are characterized in a Shiba Inu with GM2-gangliosidosis. The deletion of 3 adjacent base pairs in HEXB predicts the loss of a leucine residue at amino acid position 207 (p.Leu207del) supporting the hypothesis that GM2-gangliosidosis seen in this dog is the Sandhoff type. Because GM1-gangliosidosis also exists in this breed with almost identical clinical signs, genetic testing for both GM1- and GM2-gangliosidosis should be considered to make a definitive diagnosis.