Atomistic investigation of an Iowa Amyloid-β trimer in aqueous solution

The self-assembly of Amyloid beta (Aβ) peptides are widely accepted to associate with Alzheimer''s disease (AD) via several proposed mechanisms. Because Aβ oligomers exist in a complicated environment consisting of various forms of Aβ, including oligomers, protofibrils, and fibrils, their structure has not been well understood. The negatively charged residue D23 is one of the critical residues of the Aβ peptide as it is located in the central hydrophobic domain of the Aβ N-terminal and forms a salt-bridge D23-K28, which helps stabilize the loop domain. In the familial Iowa (D23N) mutant, the total net charge of Aβ oligomers decreases, resulting in the decrease of electrostatic repulsion between D23N Aβ monomers and thus the increase in their self-aggregation rate. In this work, the impact of the D23N mutation on 3Aβ_11–40 trimer was characterized utilizing temperature replica exchange molecular dynamics (REMD) simulations. Our simulation reveals that D23N mutation significantly enhances the affinity between the constituting chains in the trimer, increases the β-content (especially in the sequence 21–23), and shifts the β-strand hydrophobic core from crossing arrangement to parallel arrangement, which is consistent with the increase in self-aggregation rate. Molecular docking indicates that the Aβ fibril-binding ligands bind to the D23N and WT forms at different poses. These compounds prefer to bind to the N-terminal β-strand of the D23N mutant trimer, while they mostly bind to the N-terminal loop region of the WT. It is important to take into account the difference in the binding of ligands to mutant and wild type Aβ peptides in designing efficient inhibitors for various types of AD.

Amyloid beta peptide oligomers are believed to play key roles in Alzheimer''s disease pathogenesis. D23N mutation significantly changes their structure and how they bind potential inhibitors.     

MTHFR (methylenetetrahydrofolate reductase: EC 1.5.1.20) SNPs (single-nucleotide polymorphisms) and homocysteine in patients referred for investigation of fertility

Journal of Assisted Reproduction and Genetics - MTHFR, one of the major enzymes in the folate cycle, is known to acquire single-nucleotide polymorphisms that significantly reduce its activity,...     

A recessive major gene controls the mitsuda reaction in a region endemic for leprosy

BACKGROUND: Leprosy is a chronic infectious disease caused by Mycobacterium leprae. The Mitsuda reaction is a delayed granulomatous skin reaction elicited by intradermal injection of heat-killed M. leprae. Interestingly, results of the Mitsuda test are positive in the majority of individuals, even in areas not endemic for M. leprae. Like leprosy, the Mitsuda reaction is thought to be genetically controlled, but its mode of inheritance is unknown, although the role of the NRAMP1 gene has previously been reported. METHODS: We conducted a segregation analysis of quantitative Mitsuda reactivity in 168 Vietnamese nuclear families ascertained through patients with leprosy. RESULTS: We found strong evidence (P<10-9) for a major gene controlling the Mitsuda reaction independently of leprosy clinical status. Subsequent linkage analysis showed that this major gene was distinct from NRAMP1. Under the major-gene model, approximately 12% of individuals are homozygous for the recessive predisposing allele and are predicted to display high levels of Mitsuda reactivity (mean, approximately 10 mm, versus 5 mm in other individuals). CONCLUSION: We provide evidence that the Mitsuda reaction is controlled by a major gene. Our study paves the way for the identification of this gene and should provide novel insight into the mechanisms involved in granuloma formation, especially in M. leprae infection.     

杂交技术在法洛四联症中的应用

目的:总结杂交技术镶嵌治疗儿童法洛四联症(TOF)的经验。方法:外科术前介入治疗:3例有巨大体肺侧支(APCAs)的重症TOF在根治术前予以侧支血管堵塞术。外科术后镶嵌治疗:6例TOF根治术后残余分流,其中4例残余膜周部室间隔缺损,1例残余左室右房通道室间隔缺损,1例残余房间隔缺损,分别予以经导管残余心脏缺损封堵术。结果:3例有巨大APCAs的重症TOF在根治术前予以侧支血管堵塞术后随即进行外科手术,皆获得满意效果。6例TOF根治术后残余分流者行经导管封堵术封堵成功,随访无残余分流及心脏瓣膜异常,未出现心律失常。结论:杂交技术镶嵌治疗伴有巨大APCAs及术后存在残余分流的TOF安全、有效。     

Hepatitis C virus infection in systemic lupus erythematosus: a case-control study

OBJECTIVE: Viruses might be one of the elements that trigger systemic lupus erythematosus (SLE). Steroid therapy may influence the natural history of virus infections. The most frequent extrahepatic manifestations of hepatitis C virus (HCV) including arthralgia, myalgia, sicca syndrome, and antinuclear antibodies, may mimic a connective tissue disease, particularly SLE. Reports on the association between SLE and HCV infection are scarce. We investigated the association of HCV infection and SLE. METHODS: Retrospective case-control monocentric study of 19 patients with SLE and anti-HCV antibodies versus 42 randomized SLE patients without anti-HCV antibodies, matched for age and sex, coming from our cohort of 700 patients with SLE. SLE and HCV-infection features were reviewed. RESULTS: Mode of infection was blood product transfusion, drug addiction, or unknown. Prevalence of lupus clinical manifestations, antinuclear, anti-dsDNA, anti-extractable nuclear antigen antibodies, and complement levels was not different between HCV positive and negative SLE patients. Prevalence of cryoglobulin was higher in SLE patients with anti-HCV antibodies (p < 0.04), but none had a mixed cryoglobulinemia syndrome. ALT activity was increased in 11 HCV positive patients and 13 had detectable HCV RNA. Liver biopsy showed cirrhosis in 2 and mild fibrosis and activity in 5. One patient treated with interferon-alpha had a sustained virological response without SLE flare. Steroid therapy did not seem to alter HCV course. CONCLUSION: SLE in HCV positive patients shows higher prevalence of cryoglobulin without mixed cryoglobulinemia syndrome. HCV infection has moderate signs of biochemical and liver pathological severity. SLE by itself or treated with steroids does not seem to worsen HCV infection.     

Toxoplasmosis and lupus. A review of the literature apropos of 4 cases

The authors report 4 cases of toxoplasmosis in patients with acute disseminated lupus erythematosus (ADLE). In one case, a pregnant patient with serology indicative of chronic infection, infected the neonate who died of subacute toxoplasmosis. Although ADLE is a classical cause of immunodepression, toxoplasmosis is a rare complication; only 5 cases were found in a review of the literature. Toxoplasmosis infection may resemble an exacerbation of lupus; an accurate diagnosis is essential as the treatment of the two conditions is radically different. The problems of diagnosis of toxoplasmosis in immunodepressed patients are reviewed and the therapeutic approach, especially in pregnant patients, is discussed. In ADLE, the authors recommend checking toxoplasmosis serology before starting and during treatment with corticosteroids. Special attention should be paid to pregnant women with apparently chronic serological changes as neonatal infection may occur.     

Ovulation induction therapy and systemic lupus erythematosus

Improvement in the prognosis of SLE prognosis has led to considering infertility therapy. The earliest reports displayed complications such as SLE revealed by ovulation induction or thrombophlebitis. Fertility is known to be normal in women with SLE, excepting amenorrhea accompanying severe flare-ups, renal insufficiency-related hypofertility and ovarian failure secondary to cyclophosphamide therapy. Anti-phospholipid antibodies are suspected to cause defective nidation and placental ischemia. An exponential rise of serum estradiol is observed irrespective of the ovulation induction protocol used, leading to SLE flare-up and thrombosis. We have experience with 114 cycles in 21 women with SLE and/or APS. A complication (fetal loss, SLE flare-up, thrombophlebitis) revealed the underlying disease in 8 women. Eighteen pregnancies led to 9 live-births, 4 fetal deaths and 5 embryonic losses. Pregnancy rate was higher after ovulation induction using gonadotropins (25% per cycle), than clomiphene (4%). Pregnancy rate was similar after IVFETE, whether the protocol was planned or not. However, three-quarters of the pregnancies after unplanned IVFETE led to abortions. On the contrary, 6 out of 7 pregnancies after planned IVFETE led to live-births. Two women developed thrombophlebitis after gonadotropins therapy. A SLE flare-up appeared after 13 out of 62 cycles, with a flare-up rate higher after gonadotropins (27% per cycle) than clomiphene therapy (6%), and after an unplanned (30%) than a planned procedure (10%). In conclusion, ovulation induction therapy can reveal SLE or APS. Clomiphene complications are uncommon. When gonadotropin therapy is considered, a preventive anti-inflammatory therapy should be discussed in SLE patients, in conjunction with heparin and/or anti-aggregate therapy for those with asymptomatic anti-phospholipid antibodies or prior thrombotic events.