Mechanisms of gastrointestinal toxicity in neuromyelitis optica spectrum disorder patients treated with mycophenolate mofetil: insights from a mouse model and human study.

Mycophenolate mofetil (MMF) is commonly utilized for the treatment of neuromyelitis optica spectrum disorders (NMOSD). However, a subset of patients experience significant gastrointestinal (GI) adverse effects following MMF administration. The present study aims to elucidate the underlying mechanisms of MMF-induced GI toxicity in NMOSD. Utilizing a vancomycin-treated mouse model, we compiled a comprehensive data set to investigate the microbiome and metabolome in the GI tract to elucidate the mechanisms of MMF GI toxicity. Furthermore, we enrolled 17 female NMOSD patients receiving MMF, who were stratified into non-diarrhea NMOSD and diarrhea NMOSD (DNM) groups, in addition to 12 healthy controls. The gut microbiota of stool samples was analyzed using 16S rRNA gene sequencing. Vancomycin administration prevented weight loss and tissue injury caused by MMF, affecting colon metabolomes and microbiomes. Bacterial ß-glucuronidase from Bacteroidetes and Firmicutes was linked to intestinal tissue damage. The DNM group showed higher alpha diversity and increased levels of Firmicutes and Proteobacteria. The ß-glucuronidase produced by Firmicutes may be important in causing gastrointestinal side effects from MMF in NMOSD treatment, providing useful information for future research on MMF. IMPORTANCE: Neuromyelitis optica spectrum disorder (NMOSD) patients frequently endure severe consequences like paralysis and blindness. Mycophenolate mofetil (MMF) effectively addresses these issues, but its usage is hindered by gastrointestinal (GI) complications. Through uncovering the intricate interplay among MMF, gut microbiota, and metabolic pathways, this study identifies specific gut bacteria responsible for metabolizing MMF into a potentially harmful form, thus contributing to GI side effects. These findings not only deepen our comprehension of MMF toxicity but also propose potential strategies, such as inhibiting these bacteria, to mitigate these adverse effects. This insight holds broader implications for minimizing complications in NMOSD patients undergoing MMF therapy.

Neferine inhibits BMECs pyroptosis and maintains blood-brain barrier integrity in ischemic stroke by triggering a cascade reaction of PGC-1α.

Blood-brain barrier disruption is a critical pathological event in the progression of ischemic stroke (IS). Most studies regarding the therapeutic potential of neferine (Nef) on IS have focused on neuroprotective effect. However, whether Nef attenuates BBB disruption during IS is unclear. We here used mice underwent transient middle cerebral artery occlusion (tMCAO) in vivo and bEnd.3 cells exposed to oxygen-glucose deprivation/reoxygenation (OGD/R) injury in vitro to simulate cerebral ischemia. We showed that Nef reduced neurobehavioral dysfunction and protected brain microvascular endothelial cells and BBB integrity. Molecular docking, short interfering (Si) RNA and plasmid transfection results showed us that PGC-1α was the most binding affinity of biological activity protein for Nef. And verification experiments were showed that Nef upregulated PGC-1α expression to reduce mitochondrial oxidative stress and promote TJ proteins expression, further improves the integrity of BBB in mice. Intriguingly, our study showed that neferine is a natural PGC-1α activator and illustrated the mechanism of specific binding site. Furthermore, we have demonstrated Nef reduced mitochondria oxidative damage and ameliorates endothelial inflammation by inhibiting pyroptosis to improve BBB permeability through triggering a cascade reaction of PGC-1α via regulation of PGC-1α/NLRP3/GSDMD signaling pathway to maintain the integrity of BBB in ischemia/reperfusion injury.

Recent Progress on the Air-Stable Battery Materials for Solid-State Lithium Metal Batteries.

Solid-state lithium metal batteries (SSLMBs) offer numerous advantages in terms of safety and theoretical specific energy density. However, their main components namely lithium metal anode, solid-state electrolyte, and cathode, show chemical instability when exposed to humid air, which results in low capacities and poor cycling stability. Recent studies have shown that bioinspired hydrophobic materials with low specific surface energies can protect battery components from corrosion caused by humid air. Air-stable inorganic materials that densely cover the surface of battery components can also provide protection, which improves the storage stability of the battery components, broadens their processing conditions, and ultimately decreases their processing costs while enhancing their safety. In this review, the mechanism behind the surface structural degradation of battery components and the resulting consequences are discussed. Subsequently, recent strategies are reviewed to address this issue from the perspectives of lithium metal anodes, solid-state electrolytes, and cathodes. Finally, a brief conclusion is provided on the current strategies and fabrication suggestions for future safe air-stable SSLMBs.

Reshaping Zinc Plating/Stripping Behavior by Interfacial Water Bonding for High-Utilization-Rate Zinc Batteries.

Aqueous zinc batteries have emerged as promising energy storage devices; however, severe parasitic reactions lead to the exacerbated production of Zn dendrites that decrease the utilization rate of Zn anodes. Decreasing the electrolyte content and regulating the water activity are efficient means to address these issues. Herein, this work shows that limiting the aqueous electrolyte and bonding water to bacterial cellulose (BC) can suppress side reactions and regulate stable Zn plating/stripping. This approach makes it possible to use less electrolyte and limited Zn foil. A symmetric Zn cell assembles with the hydrogel electrolyte with limited electrolyte (electrolyte-to-capacity ratio E/C = 1.0 g (Ah)-1 ) cycled stably at a current density of 6.5 mA cm-2 and achieved a capacity of 6.5 mA h cm-2 and depth of discharge of 85%. Full cells with the BC hydrogel electrolyte delivers a discharge capacity of 212 mA h cm-2 and shows a capacity retention of 83% after 1000 cycles at 5 A g-1 . This work offers new fundamental insights into the effect of restricting water to reshape the Zn plating/stripping process and provides a route for designing novel hydrogel electrolytes to better stabilize and efficiently utilize the Zn anodes.

Revealing the reinforcing effect of a nanorod network on a polymer matrix through molecular dynamics simulations.

Controlling the spatial morphology of the nanorods (NRs) in a polymer matrix and understanding the structure-property relationship are crucial for fabricating high-performance polymer nanocomposites (PNCs). By employing molecular dynamics simulations, we systematically studied the structural and mechanical properties of NR filled PNCs. The simulated results showed that the NRs gradually self-assembled into a three-dimensional (3D) network upon increasing the NR-NR interaction strength. The generated 3D NR network transferred loads along the NR backbone, differing from the well dispersed system which transfers loads between NRs and nearby polymer chains. Increase of the nanorod diameter or NR content further enhanced the PNCs by improving the NR network integrity. These findings provide insights into the reinforcement mechanism of NRs toward polymer matrices and provide guidance for designing PNCs with excellent mechanical performance.

Phentolamine Significantly Enhances Macrolide Antibiotic Antibacterial Activity against MDR Gram-Negative Bacteria.

OBJECTIVES: Multidrug-resistant (MDR) Gram-negative bacterial infections have limited treatment options due to the impermeability of the outer membrane. New therapeutic strategies or agents are urgently needed, and combination therapies using existing antibiotics are a potentially effective means to treat these infections. In this study, we examined whether phentolamine can enhance the antibacterial activity of macrolide antibiotics against Gram-negative bacteria and investigated its mechanism of action. METHODS: Synergistic effects between phentolamine and macrolide antibiotics were evaluated by checkerboard and time-kill assays and in vivo using a Galleria mellonella infection model. We utilized a combination of biochemical tests (outer membrane permeability, ATP synthesis, ΔpH gradient measurements, and EtBr accumulation assays) with scanning electron microscopy to clarify the mechanism of phentolamine enhancement of macrolide antibacterial activity against Escherichia coli. RESULTS: In vitro tests of phentolamine combined with the macrolide antibiotics erythromycin, clarithromycin, and azithromycin indicated a synergistic action against E. coli test strains. The fractional concentration inhibitory indices (FICI) of 0.375 and 0.5 indicated a synergic effect that was consistent with kinetic time-kill assays. This synergy was also seen for Salmonella typhimurium, Klebsiella pneumoniae, and Actinobacter baumannii but not Pseudomonas aeruginosa. Similarly, a phentolamine/erythromycin combination displayed significant synergistic effects in vivo in the G. mellonella model. Phentolamine added singly to bacterial cells also resulted in direct outer membrane damage and was able to dissipate and uncouple membrane proton motive force from ATP synthesis that, resulted in enhanced cytoplasmic antibiotic accumulation via reduced efflux pump activity. CONCLUSIONS: Phentolamine potentiates macrolide antibiotic activity via reducing efflux pump activity and direct damage to the outer membrane leaflet of Gram-negative bacteria both in vitro and in vivo.

ARSCP: An antimicrobial residue surveillance cloud platform for animal-derived foods.

Antibiotics have been widely used for improving human and animal health and well-being for many decades. However, the enormous antibiotic usage in agriculture especially for livestock leads to considerable quantities of antibiotic residues in associated food products and can reach potentially hazardous levels for consumers. Therefore, timely detection and systematical surveillance on residual antibiotics in food materials are of significance to minimize the negative impact caused by such unwanted antibiotic leftovers. To this end, we constructed a cloud-platform-based system (ARSCP) for comprehensive surveillance of antibiotic residues in food materials. With the system, we collected 126,560 samples from 68 chicken farms across China and detected the antibiotic residues using a rapid detection colorimetric commercial (Explorer 2.0) kit and UPLC-MS/MS. Only 108 (0.085 %) of the samples contained residual antibiotics exceeding the MRLs and all data were subjected to ARSCP system to provide a landscape of antibiotic residues in China. As a proof-of-concept, we provided an overview of residual antibiotics based on data from China, but the system is generally applicable to track and monitor the antibiotic residues globally when the data from other countries are incorporated. We used the combined Explorer 2.0 and MS data to construct ARSCP, an antimicrobial residue surveillance cloud platform for raw chicken samples. ARSCP can be used for rapid detection and real-time monitoring of antibiotic residues in animal food and provides both data management and risk warning functions. This system provides a solution to improve the management of facilities that must monitor antibiotic MRLs in food animal products that can reduce the pollution of antibiotics to the environment.

Limited Lithium Loading Promises Improved Lithium-Metal Anodes in Interface-Modified 3D Matrixes.

Confining Li metal in a three-dimensional (3D) matrix has been proven effective in improving the Li-metal anodes; however, in most studies, the loading of Li in the 3D matrix is far excessive, resulting in a dense bulk Li-metal anode with a low Li-utilization rate, forfeiting the effect of the 3D matrix. Here, we show that limiting the loading of Li metal within an interface-modified 3D carbon matrix not only increases the Li-utilization rate but also improves the electrochemical performance of the Li-metal anode. We use lithiophilic Fe2O3 granules anchored on a 3D carbon fiber scaffold to guide molten Li dispersion onto the fibers with controlled Li loading. Limiting Li loading maximizes the interface lithiophilic effect of the Fe2O3 granules while preserving sufficient space for electrolyte infusion, collectively ensuring uniform Li deposition and fast Li+ transport kinetics. The Li anode with limited Li dosage achieves remarkably improved Li-anode performances, including long lifespan, low voltage polarization, and low electrochemical resistance in both the symmetric cells and full cells. The improved electrochemical performance of the limited Li anode substantiates the importance to reduce Li loading from a fresh perspective and provides an avenue for building practical Li-metal batteries.

MALDI-TOF MS for rapid detection and differentiation between Tet(X)-producers and non-Tet(X)-producing tetracycline-resistant Gram-negative bacteria.

The extensive use of tetracycline antibiotics has led to the widespread presence of tetracycline-resistance genes in Gram-negative bacteria and this poses serious threats to human and animal health. In our previous study, we reported a method for rapid detection of Tet(X)-producers using MALDI-TOF MS. However, there have been multiple machineries involved in tetracycline resistance including efflux pump, and ribosomal protection protein. Our previous demonstrated the limitation in probing the non-Tet(X)-producing tetracycline-resistant strains. In this regard, we further developed a MALDI-TOF MS method to detect and differentiate Tet(X)-producers and non-Tet(X)-producing tetracycline-resistant strains. Test strains were incubated with tigecycline and oxytetracycline in separate tubes for 3 h and then analyzed spectral peaks of tigecycline, oxytetracycline, and their metabolite. Strains were distinguished using MS ratio for [metabolite/(metabolite+ tigecycline or oxytetracycline)]. Four control strains and 319 test strains were analyzed and the sensitivity was 98.90% and specificity was 98.34%. This was consistent with the results obtained from LC-MS/MS analysis. Interestingly, we also found that the reactive oxygen species (ROS) produced by tetracycline-susceptible strains were able to promote the degradation of oxytetracycline. Overall, the MALDITet(X)-plus test represents a rapid and reliable method to detect Tet(X)-producers, non-Tet(X)-producing tetracycline-resistant strains, and tetracycline-susceptible strains.

Reducing tetracycline antibiotics residues in aqueous environments using Tet(X) degrading enzymes expressed in Pichia pastoris.

Tetracycline antibiotics (TCs) are massively produced and consumed in various industries resulting in large quantities of residuals in the environment. In this study, to achieve safe and efficient removal of residual TCs, a Pichia pastoris (P. pastoris) was gained to stably express glycosylated TCs degrading enzyme Tet(X) followed codon and expression parameter optimization of tet(X4). As expected, glycosylated Tet(X) still maintains efficient capacity of degrading TCs. The expressed Tet(X) maintained efficient TCs degrading ability over a pH range of 6.5 - 9.5 and temperature range of 17 - 47 °C. We tested this recombinant protein for its ability to degrade tetracycline in pond water and sewage models of tetracycline removal at starting levels of 10 mg/L substrate. 80.5 ± 3.8% and 26.2 ± 2.6% of tetracycline was degraded within 15 min in the presence of 0.2 µM Tet(X) and 50 µM NADPH, respectively. More importantly, the direct use of a Tet(X) degrading enzymes reduces the risk of gene transmission during degradation. Thus, the Tet(X) degrading enzyme expressed by P. pastoris is an effective and safe method for treating intractable TCs residues.

Evolutionary Trajectory of the Tet(X) Family: Critical Residue Changes towards High-Level Tigecycline Resistance.

The emergence of the plasmid-mediated high-level tigecycline resistance mechanism Tet(X) threatens the role of tigecycline as the "last-resort" antibiotic in the treatment of infections caused by carbapenem-resistant Gram-negative bacteria. Compared with that of the prototypical Tet(X), the enzymatic activities of Tet(X3) and Tet(X4) were significantly enhanced, correlating with high-level tigecycline resistance, but the underlying mechanisms remain unclear. In this study, we probed the key amino acid changes leading to the enhancement of Tet(X) function and clarified the structural characteristics and evolutionary path of Tet(X) based upon the key residue changes. Through domain exchange and site-directed mutagenesis experiments, we successfully identified five candidate residues mutations (L282S, A339T, D340N, V350I, and K351E), involved in Tet(X2) activity enhancement. Importantly, these 5 residue changes were 100% conserved among all reported high-activity Tet(X) orthologs, Tet(X3) to Tet(X7), suggesting the important role of these residue changes in the molecular evolution of Tet(X). Structural analysis suggested that the mutant residues did not directly participate in the substrate and flavin adenine dinucleotide (FAD) recognition or binding, but indirectly altered the conformational dynamics of the enzyme through the interaction with adjacent residues. Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) and UV full-wavelength scanning experiments confirmed that each mutation led to an increase in activity without changing the biochemical properties of the Tet(X) enzyme. Further phylogenetic analysis suggested that Riemerella anatipestifer served as an important incubator and a main bridge vector for the resistance enhancement and spread of Tet(X). This study expands the knowledge of the structure and function of Tet(X) and provides insights into the evolutionary relationship between Tet(X) orthologs.IMPORTANCE The newly emerged tigecycline-inactivating enzymes Tet(X3) and Tet(X4), which are associated with high-level tigecycline resistance, demonstrated significantly higher activities in comparison to that of the prototypical Tet(X) enzyme, threatening the clinical efficacy of tigecycline as a last-resort antibiotic to treat multidrug-resistant (MDR) Gram-negative bacterial infections. However, the molecular mechanisms leading to high-level tigecycline resistance remain elusive. Here, we identified 5 key residue changes that lead to enhanced Tet(X) activity through domain swapping and site-directed mutagenesis. Instead of direct involvement with substrate binding or catalysis, these residue changes indirectly alter the conformational dynamics and allosterically affect enzyme activities. These findings further broaden the understanding of the structural characteristics and functional evolution of Tet(X) and provide a basis for the subsequent screening of specific inhibitors and the development of novel tetracycline antibiotics.

Recent Progress in Designing Stable Composite Lithium Anodes with Improved Wettability.

Lithium (Li) is a promising battery anode because of its high theoretical capacity and low reduction potential, but safety hazards that arise from its continuous dendrite growth and huge volume changes limit its practical applications. Li can be hosted in a framework material to address these key issues, but methods to encage Li inside scaffolds remain challenging. The melt infusion of molten Li into substrates has attracted enormous attention in both academia and industry because it provides an industrially adoptable technology capable of fabricating composite Li anodes. In this review, the wetting mechanism driving the spread of liquefied Li toward a substrate is discussed. Following this, various strategies are proposed to engineer stable Li metal composite anodes that are suitable for liquid and solid-state electrolytes. A general conclusion and a perspective on the current limitations and possible future research directions for constructing composite Li anodes for high-energy lithium metal batteries are presented.

Rapid Detection of High-Level Tigecycline Resistance in Tet(X)-Producing Escherichia coli and Acinetobacter spp. Based on MALDI-TOF MS.

The emergence and spread of the novel mobile Tet(X) tetracycline destructases confer high-level tigecycline and eravacycline resistance in Escherichia coli and Acinetobacter spp. and pose serious threats to human and animal health. Therefore, a rapid and robust Tet(X) detection assay was urgently needed to monitor the dissemination of tigecycline resistance. We developed a rapid and simple assay to detect Tet(X) producers in Gram-negative bacteria based on matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). This MALDITet(X) test was based on the inactivation of tigecycline by a Tet(X)-producing strain after a 3-h incubation of bacterial cultures with tigecycline. Culture supernatants were analyzed using MALDI-TOF MS to identify peaks corresponding to tigecycline (586 ± 0.2 m/z) and a tigecycline metabolite (602 ± 0.2 m/z). The results were calculated using the MS ratio [metabolite/(metabolite + tigecycline)]. The sensitivity of the MALDITet(X) test with all 216 test strains was 99.19%, and specificity was 100%. The test can be completed within 3 h. Overall, the MALDITet(X) test is an accurate, rapid, cost-effective method for the detection of Tet(X)-producing E. coli and Acinetobacter spp. by determining the unique peak of an oxygen-modified derivative of tigecycline.

Nitrofurantoin Combined With Amikacin: A Promising Alternative Strategy for Combating MDR Uropathogenic Escherichia coli.

Urinary tract infections (UTI) are common infections that can be mild to life threatening. However, increased bacterial resistance and poor patient compliance rates have limited the effectiveness of conventional antibiotic therapies. Here, we investigated the relationship between nitrofurantoin and amikacin against 12 clinical MDR uropathogenic Escherichia coli (UPEC) strains both in vitro and in an experimental Galleria mellonella model. In vitro synergistic effects were observed in all 12 test strains by standard checkerboard and time-kill assays. Importantly, amikacin or nitrofurantoin at half of the clinical doses were not effective in the treatment of UPEC infections in the G. mellonella model but the combination therapy significantly increased G. mellonella survival from infections caused by all 12 study UPEC strains. Taken together, these results demonstrated synergy effects between nitrofurantoin and amikacin against MDR UPEC.

Guiding Uniform Li Plating/Stripping through Lithium-Aluminum Alloying Medium for Long-Life Li Metal Batteries.

The uncontrolled growth of Li dendrites upon cycling might result in low coulombic efficiency and severe safety hazards. Herein, a lithiophilic binary lithium-aluminum alloy layer, which was generated through an in situ electrochemical process, was utilized to guide the uniform metallic Li nucleation and growth, free from the formation of dendrites. Moreover, the formed LiAl alloy layer can function as a Li reservoir to compensate the irreversible Li loss, enabling long-term stability. The protected Li electrode shows superior cycling over 1700 h in a Li|Li symmetric cell.

Positive association of CC2D1A and CC2D2A gene haplotypes with mental retardation in a Han Chinese population.

The CC2D1A and CC2D2A genes are involved in Ca(2+)-regulated signaling pathways and have recently been implicated in the etiology of mental retardation (MR). The aim of this study was to investigate whether CC2D1A and CC2D2A polymorphisms are associated with susceptibility to MR in a Han Chinese population using a family based association approach. The sample included 172 trios (parents and offspring), and all subjects were genotyped for several single-nucleotide polymorphisms covering CC2D1A and CC2D2A. Linkage disequilibrium (LD) analysis revealed that the rs6511901 and rs10410239 polymorphisms of CC2D1A were in strong LD (D'=0.865), and haplotype analysis showed evidence for over-transmission from parents to MR offspring (p=0.0009). The LD analysis also revealed that CC2D2A single-nucleotide polymorphisms rs10025837, rs13116304, and rs7661102 were in strong LD (D'=0.848), and haplotype analysis showed significant transmission disequilibrium (p=0.0004). The results suggest the involvement of CC2D1A and CC2D2A in MR in the Han Chinese population, and some specific haplotypes may be susceptible or protective.

[Anassociation study between OPHN1 gene rs492933 polymorphism and mental retardation in children of the Qinba Mountain region.].

The OPHN1 gene encodes a Rho-GTPase activating protein (RhoGAP), and mutations in OPHN1 are responsible for non-specific X-linked mental retardation (NSMR). A SNP located in the 5'-untranslated region (UTRs) of OPHN1 (rs492933) was examined by PCR-RFLP to assess its contribution to cognitive ability in 234 unrelated healthy and MR children in the Qinba Mountain region in Shaanxi. The allelic frequencies of rs492933 were 0.826 for the C allele and 0.174 for the T allele. Genotype frequencies and allelic frequencies were not significantly different between the MR and the controls, or between the borderline group and the controls. In conclusion, there is no association between the OPHN1 gene polymorphism and NSMR in the Qinba Mountain region children.

[Relationship between the polymorphisms of GDI1, children NSMR and their intelligence in Qinba region].

The subjects of this study were recruited from Zha Shui and An Kang counties in the Qinba mountain region located in Middle-west China. The present study discussed the relationship between the variations of GDI1 with the children NSMR and their intelligence levels. The case-control association analysis method was used to analyze the association between the polymorphisms of two functional SNPs (rs2276462 and rs11549300) located in splicing site of the seventh exon and the eighth exon respectively, with NSMR and their different intelligence levels. It does not find out the polymorphism of rs2276462, because of its conservation. The results of case-control analysis indicated that, no association between the rs11549300 polymorphisms and children NSMR (P >0.05), but its polymorphisms may be related to intelligence levels of children in Qinba region (P =0.03). And a further work should be done to verify the conclusion of this study using the more genetic markers of GDI1 in a larger sample.

Association between a functional COMT polymorphism, mental retardation and cognition in Qinba area children.

Catechol-O-methyl transferase (COMT) plays an important role in the metabolism of neurotransmitters. Two alleles of the COMT gene as a result of a G/A transition in the exon 4 can lead to different COMT enzymatic activities. Much genetic research has revealed that this COMT functional polymorphism was related to human psychiatric disorders. Polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) methods were used to discern the relationships among the functional polymorphism of COMT, mental retardation (MR), and general cognitive ability of children. The results of the case-control analysis showed that there was no association between the frequencies of genotypes of COMT and MR (chi2=0.776, P>0.05) or between the frequency of COMT alleles and MR (chi2=0.335, P>0.05). COMT polymorphism was found in children whose intelligence quotient (IQ) was above 55. In normal children (IQ> or =85), the frequencies of high-activity allele COMTH and the homozygote genotype COMTHH were 60.98% and 79.28%, respectively. Both were higher than those of the borderline group (46.67% and 70.67%, 0.10 > P>0.05). Therefore, the result of this study suggests that this functional polymorphism is not an important risk factor for MR, but the COMTHH genotype may have a positive effect on cognitive performance in normal children in the Qinba area.

An association study between the transthyretin (TTR) gene and mental retardation.

It is known that in the pathogenesis of mental retardation (MR), both genetic and environmental factors (particularly iodine deficiency) appear to play a critical role. Transthyretin (TTR) transports between 20% and 30% of serum thyroxine in normal individuals and it is the main T(4)-binding protein in CSF. Variability in the TTR gene may influence risk for iodine-deficiency-based MR. The SNPs we selected from dbSNP were detected and identified using ARMS-PCR and sequencing methods, and we identified five novel sequence variants. Singular-locus association analysis indicated no association between the TTR gene and MR. In haplotype analysis, however, we found a haplotype CGTG+ (rs723744/G+6649C/T+6690C/rs2276382/del9) showed a weak positive association with MR (chi(2) = 6.699, p = 0.035). Finally, we concluded that the weak positive result is more likely to be due to sampling error and the small size of this haplotype resulting from its relative low frequency. Our negative results provide no evidence that variants of TTR gene influence susceptibility to MR in the iodine-deficient areas of China and suggest that there may be a compensatory mechanism(s) in humans and mice, which work(s) to compensate the effect of mutation in the TTR gene on MR.