Identification and expression of cathepsin B from the freshwater mussel Cristaria plicata

Cathepsin B plays crucial roles in host immune defense against pathogen infection. In present study, a cathepsin B gene from the freshwater mussel, Cristaria plicata (CpCathB) was cloned and characterized. The full-length cDNA of CpCathB was 1825 bp, and contained a 5' untranslated region (UTR) of 36 nucleotides, an open reading frame (ORF) of 1044 bp and a 3' UTR of 745 bp with a poly (A) tail. The deduced CpCathB protein was encoded as a preproenzyme with 347 amino acid residues and predicted molecular weight of 38.55 kDa. Sequence alignment revealed that CpCathB protein shared 56% - 60.7% identity comparison with other species. The predicted tertiary structure of CpCathB protein was highly similar to that of human. The CpCathB mRNA was expressed in hemocytes, hepatopancreas, adductor muscle, gills and mantle tissues of healthy mussels, and the highest expression level was in hepatopancreas. The transcripts of CpCathB were increased in hemocytes and hepatopancreas from mussels after Aeromonas hydrophila challenge. Moreover, the recombinant CpCathB was expressed in the Escherichia coli Rosetta-gami (DE3) strain. The maximum titer of the anti-CpCathB polyclonal antibodies was 1:640,000.The CpCathB protein had a higher expression in hepatopancreas and mantle and a lower level in hemocytes.

Review article: Asia-Pacific consensus recommendations on endoscopic tissue acquisition for biliary strictures

BACKGROUND

Pre-operative tissue diagnosis for suspected malignant biliary strictures remains challenging.

AIM

To develop evidence-based consensus statements on endoscopic tissue acquisition for biliary strictures.

METHODS

The initial draft of statements was prepared following a systematic literature review. A committee of 20 experts from Asia-Pacific region then reviewed, discussed, and modified the statements. Two rounds of independent voting were conducted to reach a final version. Consensus was considered to be achieved when 80% or more of voting members voted "agree completely" or "agree with some reservation."

RESULTS

Eleven statements achieved consensus. The choice of tissue sampling modalities for biliary strictures depends on the clinical setting, the location of lesion, and availability of expertise. Detailed radiological and endoscopic evaluation is useful to guide the selection of appropriate tissue acquisition technique. Standard intraductal biliary brushing and/or forceps biopsy is the first option when endoscopic biliary drainage is required with an overall (range) sensitivity and specificity of 45% (26%-72%) and 99% (98%-100%), and 48% (15%-100%) and 99% (97%-100%), respectively, in diagnosing malignant biliary strictures. Probe-based confocal laser endomicroscopy and fluorescence in situ hybridisation using 4 fluorescent-labelled probes targeting chromosomes 3, 7, 17 and 9p21 locus may be added to improve the diagnostic yield. Cholangioscopy-guided biopsy and EUS-guided tissue acquisition can be considered after prior negative conventional tissue sampling with an overall (range) sensitivity and specificity of 60% (38%-88%) and 98% (83%-100%), and 80% (46%-100%) and 97% (92%-100%), respectively, in diagnosing malignant biliary strictures.

CONCLUSION

These consensus statements provide evidence-based recommendations for endoscopic tissue acquisition of biliary strictures.

[Anterior cervical discectomy and fusion to treat cervical spondylosis with sympathetic symptoms]

OBJECTIVE

To investigate the clinical effectiveness of polytheretherketone (PEEK) cages assisted anterior cervical discetomy and fusion (ACDF) to treat cervical spondylosis with sympathetic symptoms.

METHODS

Retrospective analysis was undertaken for 39 patients who were diagnosed as cervical spondylosis with sympathetic symptoms and underwent ACDF with PEEK cages. Radiographs obtained before surgery, after surgery, and at the final follow-up were assessed for quality of fusion. The following criteria were used for assessing radiographic success of fusion: (1) endplate obliterated with no lucent lines; (2) obliteration of disc space by bony trabeculae; (3) less than 2°of intervertebral motion or 2 mm of motion between the spinous processes at the operated segment on flexion-extension lateral radiographs. The sympathetic symptoms including vertigo, headache, tinnitus, nausea and vomiting, heart throb, hypomnesia and gastroenterological discomfort were scored by 20-point system preoperatively, 2 months postoperatively and at the final follow-up. The recovery rate and clinical satisfaction rate were also evaluated. Surgical complications were also assessed.

RESULTS

They were followed up for at least one year. The mean follow-up was 15.6 months. Radiographs of the cervical spine at the last follow-up revealed a solid fusion with no signs of a pseudoarthrosis in 36 cases. In two patients delayed union and bony fusion were achieved at the end of 9 and 11 months. Pseudoarthosis was found in 1 case but the patient had no symptoms. The score of sympathetic symptoms before surgery, 2 months after surgery and at the final follow-up were 8.4±1.0,2.2±0.3,and 2.4±0.3, respectively. There were 22 excellent cases, 15 good cases, 1 fair case and 1 bad case in terms of RR. Good to excellent results were attained in 95% of theses patients. The sympathetic symptoms improved in all the patients and the score was significantly improved after surgery. There was one patient who had cerebral spinal fluid leakage but he recovered one week after surgery. Two patients felt a mild swallowing discomfort, but it disappeared within one month after surgery. Subcutaneous hematoma occurred in one patient due to obstructed drainage. It was cleared two days after surgery.

CONCLUSION

Cervical spondylosis patients with sympathetic symptoms may be managed successfully with ACDF using PEEK cages. Successful clinical results regarding symptom improvement and general satisfaction with the surgical procedure depend not only on obtaining successful decompression and radiographic fusion but also on patient selection.

[Epidemiology related to soil-borne nematode disease in Danzhou city, Hainan province]

Objective: To understand the prevalence, trend and related factors on soil-borne nematode in Danzhou city to provide information for prevention and control of the disease. Methods: According to the guidelines set by the National National soil-borne nematode technical solutions, one village was randomly chosen from every township as the monitoring location, in the east, west, south and north parts of Danzhou city. A total of 200 residents aged 3 years and over were randomly selected in each monitoring site, with modified Kato thick smear and Cellophane tape anal swab used for microscopy. Results: In this survey, we retrospectively analyzed the rates on soil borne nematode infection in five monitoring locations of Danzhou city and the results showed that the overall positive rates of infection was 19.5% (195/1 000). Comparing with the previous surveys, rates on soil-borne parasites infection were decreasing. The main types of soil-borne nematode infection appeared as roundworm, whipworm, hookworm and pinworm in Danzhou city, with rate of hookworm-egg infection ranking the highest (42.5%, 85/200) in Dacheng. The infection rate was seen significantly higher in females than males. People aged over 60 and between 3-10, had a higher rates of infection. Rate on multiple infections reached 16.9%, including 5 triple infection cases. Conclusion: Rates of infection on soil-borne nematodes in Danzhou city showed a decreasing trend from 2013 to 2016 with hookworm and whipworm as the major ones.

Nicotine inhibits osteogenic differentiation of human periodontal ligament cells under cyclic tensile stress through canonical Wnt pathway and α7 nicotinic acetylcholine receptor

BACKGROUND AND OBJECTIVES

Nicotine, the main psychoactive component of tobacco, affects cell metabolism, proliferation, adhesion and, importantly, the osteogenic differentiation of fibroblasts. Approximately 15% of all orthodontic patients are adults among who one-fifth are smokers. Hence, it is necessary to have insight into the effects of nicotine on the osteogenic differentiation of hPDLCs during orthodontic tooth movement. This study aimed to investigate the effects and mechanisms of nicotine on the osteogenic differentiation of human periodontal ligament cells (hPDLCs) under the application of cyclic tensile stress.

MATERIAL AND METHODS

hPDLCs were obtained from donor third molars. The hPDLCs were treated with nicotine and/or cyclic tensile stress that was applied with a cell stress plus unit. The effect of nicotine on cell viability was analyzed using the MTT assay. The osteogenic differentiation of hPDLCs was detected by alkaline phosphatase staining, Alizarin Red S staining, quantitative real-time polymerase chain reaction and western blotting.

RESULTS

In combination with cyclic tensile stress, nicotine prevented the tensile stress-induced increase in alkaline phosphatase activity, formation of mineralization nodules and the upregulation of mRNA and protein expression of Runt-related transcription factor 2, transcription factor Sp7 and collagen type I; however, canonical Wnt pathway was activated. Furthermore, the addition of Dickkopf-related protein 1 and α-bungarotoxin counteracted the negative effect of nicotine and rescued the osteogenic differentiation of hPDLCs, respectively.

CONCLUSION

These results indicate that nicotine prevents the increased osteogenic potential of hPDLCs induced by cyclic tensile stress by binding to an α7 nicotinic acetylcholine receptor and activating the canonical Wnt pathway.

Cystathionine γ-Lyase Is Involved in the Renoprotective Effect of Brief and Repeated Ischemic Postconditioning After Renal Ischemia/Reperfusion Injury in Diabetes Mellitus

BACKGROUND

The aim of this study was to determine whether the protective effects of brief and repeated ischemic postconditioning (IPoC) are associated with the modulation of cystathionine γ-lyase (CSE) expression after renal ischemia/reperfusion (I/R) injury in diabetes mellitus (DM).

METHODS

We subjected diabetic rats to 45 minutes of ischemia followed by reperfusion at 24 hours. Before reperfusion, diabetic rats were treated with 3 cycles of 6 seconds of reperfusion, followed by 6 seconds of ischemia. DL-Propargylglycine (PAG, a CSE inhibitor) was administered to the diabetic rats to investigate its effects on the severity of renal I/R injury in diabetes mellitus (DM). Blood samples and left kidneys were collected for the measurement of blood urea nitrogen (BUN) and serum creatinine (SCr) levels and renal pathologic changes. Western blot and immunochemistry techniques were also performed for the localization of CSE. Levels of superoxidase dismutase (SOD), malonyldialdehyde (MDA), tumor necrosis-alpha (TNF-α), and hydrogen sulfide (H₂S) were quantified using commercially available kits.

RESULTS

The results showed that BUN and SCr levels increased on renal ischemia/reperfusion injury (RI/RI) in the DM group. Diabetic rats treated with IPoC exhibited significantly less renal damage on I/R. Kit measurements showed that IPoC could markedly inhibit the levels of MDA and TNF-α and also improve SOD and H₂S levels. Western blot and immunochemistry showed that expression of CSE was downregulated on I/R in the DM group and IPoC upregulated CSE expression, whereas PAG treatment resulted in opposite effects.

CONCLUSION

Our findings show that brief and repeated IPoC increased the expression of CSE after I/R in DM, and the modulation of CSE may underlie the renoprotective effect of IPoC.

A novel HLA-A*31 allele, A*31:126N, was identified by sequence-based typing

A novel allele A*31:126N was identified in a Chinese individual by sequence-based typing method.

[Phrenic nerve stimulation protects against mechanical ventilation-induced diaphragmatic dysfunction through myogenic regulatory factors]

Objective: To explore the protective effect of electrical stimulation of phrenic nerve on diaphragmatic function during mechanical ventilation. Methods: Forty healthy adult SD rats were randomly divided into 5 groups: blank control group (BC), spontaneous breathing group (SB), electrical stimulation group (ES), mechanical ventilation group (MV), and electrical stimulation and mechanical ventilation group (MS). The rats in each group were treated for 18 h except for the BC group. After treatment, the diaphragm muscle tissue was obtained and the diaphragm contractility including peak-to-peak value(Vpp) and maximum rate of contraction(+ dT/dt max) were measured. Expression of MyoD and myogenin were detected. Results: Except for the ES and the MS groups, there was a significant difference for peak-to-peak value (Vpp) between each 2 groups (P<0.05). Expression levels of MyoD in treatment groups were also significantly different (P<0.05). Expressions of MS(Q-PCR 2(-ΔΔCt) value: 11.66±2.80) and MV(Q-PCR 2(-ΔΔCt) value: 40.89±24.71) in the treatment group were significantly different (P<0.05). The expression of myogenin in the MS and the MV groups were significantly different from those of the BC group(P<0.05), however there was no significant difference between the MS(Q-PCR 2(-ΔΔCt) value: 2.58±2.75) and the MV group(Q-PCR 2(-ΔΔCt) value: 1.63±0.71). Conclusions: Electrical stimulation of the phrenic nerve can change the expression level of MyoD and myogenin to offset mechanical ventilation induced diaphragmatic function damage, and therefore plays a protective effect on the diaphragm.

Extracellular signal-regulated kinase activation in the spinal cord contributes to visceral hypersensitivity induced by craniofacial injury followed by stress

BACKGROUND

We previously developed an animal model to examine mechanisms that underlie the emergence of visceral hypersensitivity modeling pain characteristics of temporomandibular disorder (TMD) patients with comorbid irritable bowel syndrome (IBS). In ovariectomized (OVx) rats with estradiol (E2) replacement, visceral hypersensitivity developed subsequent to masseter muscle inflammation followed by repeated forced swim (FS) stress. The purpose of this study was to investigate whether activation of extracellular signal-regulated kinase (ERK) in the spinal cord contributes to visceral hypersensitivity in this overlapping pain model.

METHODS

In OVx with E2 replacement rats masseter muscle inflammation was followed by 3 day FS (comorbid condition). Depression-like behaviors were assessed by sucrose preference and in the elevated plus maze, and visceral sensitivity was measured by the visceromotor response (VMR) to colorectal distention. The protein level of ERK1/2 and phosphorylated ERK1/2 (p-ERK1/2) in the L6-S2 dorsal spinal cord was analyzed by western blot.

KEY RESULTS

FS stress decreased sucrose consumption in E2 replaced rats in sucrose preference test. The expression of p-ERK1/2 in the L6-S2 dorsal spinal cord increased significantly in E2 with comorbid rats. Intrathecal injection of mitogen-activated protein kinase (MAPK) kinase (MEK) inhibitor PD98059 blocked the visceral hypersensitivity induced by masseter muscle inflammation combined with FS stress.

CONCLUSIONS & INFERENCES

These data indicate that ERK1/2 activation contributes to the visceral hypersensitivity evoked by craniofacial inflammation pain combined with stress. The results may provide a new therapeutic avenue for alleviating overlapping pain conditions.

Non-alcoholic fatty liver disease is associated with stroke severity and progression of brainstem infarctions

BACKGROUND AND PURPOSE

Non-alcoholic fatty liver disease (NAFLD) is closely correlated to visceral obesity, dyslipidaemia, insulin resistance and type 2 diabetes mellitus. We sought to assess the association between a specific stroke subgroup, brainstem infarctions (BSIs) and NAFLD. Furthermore, we evaluated whether NAFLD is an independent risk factor in patients with BSIs.

METHODS

Non-alcoholic fatty liver disease was assessed in 306 patients with radiologically confirmed BSIs via liver ultrasound. Differences between patients with and without NAFLD were compared. Data associated with stroke severity and progression after admission were collected.

RESULTS

Non-alcoholic fatty liver disease was found in 130 (42.5%) patients with acute BSIs; 58 (19.0%) had National Institutes of Health Stroke Scale scores >7 and 57 (18.6%) had progression after admission. Initial National Institutes of Health Stroke Scale scores, incidence of progression and stroke severity, and modified Rankin Scale scores at discharge were significantly higher in patients with NAFLD than in those without NAFLD. NAFLD was associated with stroke severity [Cox regression: hazard ratio (HR), 2.243; 95% confidence interval (CI), 1.254-4.013, P < 0.01]. This risk remained statistically significant after controlling for age, gender, diabetes mellitus and C-reactive protein (HR, 2.327; 95% CI, 1.252-4.324, P < 0.01). In addition, NAFLD was associated with progression (HR, 2.155; 95% CI, 1.201-3.865, P < 0.05) and remained significant after controlling for age, gender, diabetes mellitus, fibrinogen and C-reactive protein (HR, 2.378; 95% CI, 1.260-4.486, P < 0.01).

CONCLUSIONS

These results suggest that NAFLD is a potential risk factor when evaluating the severity and progression of acute BSIs. This relationship is independent of classic risk factors and metabolic syndrome features.

Machine learning algorithms based on signals from a single wearable inertial sensor can detect surface- and age-related differences in walking

The aim of this study was to investigate if a machine learning algorithm utilizing triaxial accelerometer, gyroscope, and magnetometer data from an inertial motion unit (IMU) could detect surface- and age-related differences in walking. Seventeen older (71.5 ± 4.2 years) and eighteen young (27.0 ± 4.7 years) healthy adults walked over flat and uneven brick surfaces wearing an inertial measurement unit (IMU) over the L5 vertebra. IMU data were binned into smaller data segments using 4-s sliding windows with 1-s step lengths. Ninety percent of the data were used as training inputs and the remaining ten percent were saved for testing. A deep learning network with long short-term memory units was used for training (fully supervised), prediction, and implementation. Four models were trained using the following inputs: all nine channels from every sensor in the IMU (fully trained model), accelerometer signals alone, gyroscope signals alone, and magnetometer signals alone. The fully trained models for surface and age outperformed all other models (area under the receiver operator curve, AUC = 0.97 and 0.96, respectively; p ≤ .045). The fully trained models for surface and age had high accuracy (96.3, 94.7%), precision (96.4, 95.2%), recall (96.3, 94.7%), and f1-score (96.3, 94.6%). These results demonstrate that processing the signals of a single IMU device with machine-learning algorithms enables the detection of surface conditions and age-group status from an individual's walking behavior which, with further learning, may be utilized to facilitate identifying and intervening on fall risk.

Chiral Extrapolations of the ρ(770) Meson in Nf = 2 + 1 Lattice QCD Simulations

Several lattice QCD simulations of meson-meson scattering in p-wave and Isospin = 1 in Nf = 2 + 1 flavours have been carried out recently. Unitarized Chiral Perturbation Theory is used to perform extrapolations to the physical point. In contrast to previous findings on the analyses of Nf = 2 lattice data, where most of the data seems to be in agreement, some discrepancies are detected in the Nf = 2 + 1 lattice data analyses, which could be due to different masses of the strange quark, meson decay constants, initial constraints in the simulation, or other lattice artifacts. In addition, the low-energy constants are compared to the ones from a recent analysis of Nf = 2 lattice data.

Space-Time Approach for Disturbance Detection and Classification

A major challenge facing future grid systems is to identify the source of abnormal behaviors caused by faults or voltage instability. In this paper Phasor Measurement Units (PMUs) have been considered for detecting disturbances and degradation in the grid. Considering that the source of voltage instability mainly impacts neighboring areas, we present a simple and yet efficient algorithm that can identify affected areas. The algorithm is based on K-Mean optimization that classifies PMUs into different classes of power quality. We introduce the concept of a space-time solution to identify multiple faults. Since this is a multi-objective problem, we extend the K-mean algorithm to achieve space-time optimization in two successive stages (i.e., time and space). As an alternative approach to the space-time solution, we also present a hierarchical network that is based on a distributed mapping technique. This approach may only require time-based clustering as it limits the PMU population search to a small local region. We used our real-time Virtual PMU (VPMU) embedded into our software in the loop testbed to verify the performance of the proposed schemes. For the IEEE 39-bus transmission system, it is shown that the proposed space-time synchrophasor data classification scheme is capable of detecting and isolating areas in the grid that suffer from multiple disturbances, such as faults.

A Fast Recursive Algorithm For Spectrum Tracking in Power Grid Systems

A major challenge for future wide area measurement systems is how to efficiently monitor and control the power system, which requires accurate and real-time tracking of the phase, frequency, and Power Factor (PF) of the system. The presence of inter and sub harmonics, especially in a distribution system caused by widely used non-linear power loads, rectifiers, and inverters, will distort estimation of phase/frequency and make it difficult to track the voltage, current and frequency variations. In this paper we present a new approach to identify and track the harmonics, sub-harmonics and inter-harmonics, as well as observe their impact on the power system. We propose a two-stage processing approach that consists of a subspace-based estimation method to detect and identify all harmonic components, followed by a low-complexity fast tracking algorithm to monitor frequency variations of voltage and current signals in real-time with great accuracy. The simulation results show that the proposed approach can provide highly reliable estimation and fast tracking of the harmonic components, while avoiding the impact of time variance.

[The role and significance of digital reconstruction technique in liver segments based on portal vein structure]

Objective: To study the segment of liver according to the large amount of three-dimensional(3D) reconstructive images of normal human livers and the vascular system, and to recognize the basic functional liver unit based on the anatomic features of the intrahepatic portal veins. Methods: The enhanced CT primitive DICOM files of 1 260 normal human livers from different age groups who treated from October 2013 to February 2017 provided by 16 hospitals were analyzed using the computer-aided surgery system.The 3D liver and liver vascular system were reconstructed, and the digital liver 3D model was established.The vascular morphology, anatomical features, and anatomical distributions of intrahepatic portal veins were statistically analyzed. Results: The digital liver model obtained from the 3D reconstruction of CAS displayed clear intrahepatic portal vein vessels of level four.Perform a digital liver segments study based on the analysis of level four vascular distribution areas.As the less anatomical variation of left hepatic portal vein, the liver was classified into four types of liver segmentation mainly based on right hepatic portal vein.Type A was similar to Couinaud or Cho's segmentation, containing 8 segments(537 cases, 42.62%). Type B contained 9 segments as there are three ramifications of right-anterior portal vein(464 cases, 36.82%). The main difference for Type C was the variation of right-posterior portal vein which was sector shape(102 cases, 8.10%). Type D contained the cases with special portal vein variations, which needs three-dimensional simulation to design individualized liver resection plan(157 cases, 12.46%). These results showed that there was no significant difference in liver segmental typing between genders(χ(2)=2.179, P=0.536) and did not reveal any significant difference in liver segmental typing among the different age groups(χ(2)=0.357, P=0.949). Conclusions: The 3D digital liver model can demonstrate the true 3D anatomical structures, and its spatial vascular variations.The observation of anatomic features, distribution areas of intrahepatic portal veins and individualized liver segmentation achieved via digital medical 3D visualization technology is of great value for understand the complexity of liver anatomy and to guide the precise hepatectomy.

Multidrug and Mupirocin Resistance in Environmental Methicillin-Resistant Staphylococcus aureus (MRSA) Isolates from Homes of People Diagnosed with Community-Onset MRSA Infection

Patients with community-onset (CO) methicillin-resistant Staphylococcus aureus (MRSA) infections contribute to MRSA contamination of the home environment and may be reexposed to MRSA strains from this reservoir. This study evaluates One Health risk factors, which focus on the relationship between humans, animals, and the environment, for the increased prevalence of multiple antimicrobial-resistant MRSA isolates in the home environment. During a trial of patients with CO-MRSA infection, MRSA was isolated from the household environment at the baseline and 3 months later, following randomization of patients and household members to mupirocin-based decolonization therapy or an education control group. Up to two environmental MRSA isolates collected at each visit were tested. MRSA isolates were identified in 68% (65/95) of homes at the baseline (n = 104 isolates) and 51% (33/65) of homes 3 months later (n = 56 isolates). The rates of multidrug resistance (MDR) were 61% among isolates collected at the baseline and 55% among isolates collected at the visit 3 months later. At the baseline, 100% (14/14) of MRSA isolates from rural homes were MDR. While antimicrobial use by humans or pets was associated with an increased risk for the isolation of MDR MRSA from the environment, clindamycin use was not associated with an increased risk for the isolation of MDR MRSA. Incident low-level mupirocin-resistant MRSA strains were isolated at 3 months from 2 (5%) of 39 homes that were randomized to mupirocin treatment but none of the control homes. Among patients recently treated for a CO-MRSA infection, MRSA and MDR MRSA were common contaminants in the home environment. This study contributes to evidence that occupant use of antimicrobial drugs, except for clindamycin, is associated with MDR MRSA in the home environmental reservoir. (This study has been registered at ClinicalTrials.gov under registration no. NCT00966446.)IMPORTANCE MRSA is a common bacterial agent implicated in skin and soft tissue infections (SSTIs) in both community and health care settings. Patients with CO-MRSA infections contribute to environmental MRSA contamination in these settings and may be reexposed to MRSA strains from these reservoirs. People interact with natural and built environments; therefore, understanding the relationships between humans and animals as well as the characteristics of environmental reservoirs is important to advance strategies to combat antimicrobial resistance. Household interactions may influence the frequency and duration of exposure, which in turn may impact the duration of MRSA colonization or the probability for recurrent colonization and infection. Therefore, MRSA contamination of the home environment may contribute to human and animal recolonization and decolonization treatment failure. The aim of this study was to evaluate One Health risk factors that may be amenable to intervention and may influence the recovery of MDR and mupirocin resistance in CO-MRSA isolates.

A novel missense mutation in AIFM1 results in axonal polyneuropathy and misassembly of OXPHOS complexes

BACKGROUND AND PURPOSE

Apoptosis-inducing factor mitochondrion-associated-1 (AIFM1) in mitochondria has captured a great deal of attention due to its well-described function in apoptosis. Mutations in AIFM1 have resulted in multiple clinical phenotypes, including X-linked Charcot-Marie-Tooth disease type 4. These syndromes usually involve multiple locations within the nervous system and/or multiple organs. This study describes a novel missense mutation in AIFM1 and its associated peripheral nerve disease.

METHODS

Patients with AIFM1 mutation were characterized clinically, electrophysiologically, genetically and by magnetic resonance imaging. The fibroblasts were isolated from the patients to study mitochondrial OXPHOS complexes.

RESULTS

We identified a family with a novel missense mutation (Phe210Leu) in AIFM1 who developed an isolated late-onset axonal polyneuropathy in which the central nervous system and other organs were spared. Interestingly, this Phe210Leu mutation resulted in abnormal assembly of mitochondrial complex I and III, and failed to disrupt AIFM1 binding with mitochondrial intermembrane space import and assembly protein 40 (MIA40) in the patients' cells. Deficiency of either AIFM1 or MIA40 is known to impair the assembly of mitochondrial complex I and IV. However, levels of both AIFM1 and MIA40 were unchanged.

CONCLUSIONS

Phe210Leu mutation in AIFM1 induces an axonal polyneuropathy that might be contributed by the misassembly of mitochondrial complex I and III. This misassembly appears to be independent of the traditional mechanism via AIFM1/MIA40 deficiency.