Bilateral corneal perforation in familial amyloidotic polyneuropathy

Purpose We report the progression of bilateral central perforating ulceration in the cornea of a patient with familial amyloidotic polyneuropathy (FAP), also known as hereditary Portuguese amyloidosis, who received two corneal grafts in an interval of 6 years. The pathology of the original host and the grafted cornea is described.Methods Overall histology and immunolocalization of transthyretin, amyloid beta (A), and epithelial and inflammatory markers were performed.Results Corneal sensitivity and tear film were reduced. The grafted but not the original tissue contained amyloid deposits with transthyretin immunoreactivity. Epithelial and stromal thinning was accentuated in the graft, with epithelial dysplasia, hyperproliferation, and parakeratosis. Abundance of basement membrane material in hyperproliferative regions suggested recurrent attempts of wound healing. Activated keratocytes, ingrowth of vessels, infiltrated inflammatory, and immune cells reflect both acute and chronic inflammation.Conclusion Amyloid deposits may progressively reduce corneal sensitivity and damage epithelium and stroma. Corneal neuropathy, together with impaired tear film, may entail the pathology of dry eyes as a bystander effect, contributing to exacerbation of epithelial injury, deregulated proliferation, and parakeratosis. Once established, both acute and chronic inflammation may sustain progression of the corneal pathology.     

The transthyretin gene is expressed in human and rodent dorsal root ganglia

The transthyretin (TTR) gene is mainly expressed in the liver and choroid plexus of the brain. Most cases of familial amyloidotic polyneuropathy (FAP) are caused by TTR gene mutations, and characterized by amyloid deposition in the peripheral nervous system. We hypothesized that the TTR gene may be expressed in the peripheral nervous system. We analyzed TTR gene expression in several parts of the human, mouse and rat peripheral nervous systems using RT-PCR. To determine the sites of TTR synthesis in the dorsal root ganglia (DRG), mouse DRG were examined by in situ hybridization, laser capture microdissection and RT-PCR, and immunohistochemistry. TTR mRNA was detected in the DRG and cauda equina of humans and rodents by RT-PCR. TTR mRNA was not detected in the sural nerve, lumbar plexus or sympathetic ganglia in humans, or in the sciatic nerve in rodents. In mouse DRG, TTR mRNA was localized in the peripheral glial cells. No TTR-like immunoreactivity was observed in these tissues except for the perineurium. The TTR gene is probably expressed in the peripheral glial cells of the DRG. TTR synthesis in the DRG may be important for the involvement of the peripheral nervous system in FAP.     

Two transthyretin variants (TTR Ala-49 and TTR Gln-89) in two Sicilian kindreds with hereditary amyloidosis.

We report the biochemical and molecular characterization of two new transthyretin (TTR) variants in two Italian families with hereditary amyloidosis. Both families presented neuropathy and cardiomyopathy but they differ in other clinical features. These TTR variants were previously detected by isoelectric focusing (IEF); one is a neutral TTR variant and the other one is basic. By protein and DNA analysis the neutral variant was found to have a substitution of an alanine for a threonine residue at position 49 (TTR Ala-49) of the polypeptide chain. The basic variant has a glutamine residue replacing glutamate at position 89 (TTR Gln-89).     

Polineuropatía amiloidótica familiar I por mutación Val50Met (Val30Met) en el gen de la transtiretina

Introduction

Transthyretin-related familial amyloid polyneuropathy (TTR-FAP) typically arises as an autonomic neuropathy primarily affecting small fibres and it occurs in adult patients in their second or third decades of life. It progresses rapidly and can lead to death in approximately 10 years. Other phenotypes have been described in non-endemic areas.

New CYP1 genes in the frog Xenopus (Silurana) tropicalis: induction patterns and effects of AHR agonists during development

The Xenopus tropicalis genome shows a single gene in each of the four cytochrome P450 1 (CYP1) subfamilies that occur in vertebrates, designated as CYP1A, CYP1B1, CYP1C1, and CYP1D1. We cloned the cDNAs of these genes and examined their expression in untreated tadpoles and in tadpoles exposed to waterborne aryl hydrocarbon receptor agonists, 3,3′,4,4′,5-pentachlorobiphenyl (PCB126), β-naphthoflavone (βNF), or indigo. We also examined the effects of PCB126 on expression of genes involved in stress response, cell proliferation, thyroid homeostasis, and prostaglandin synthesis. PCB126 induced CYP1A, CYP1B1, and CYP1C1 but had little effect on CYP1D1 (77-, 1.7-, 4.6- and 1.4-fold induction versus the control, respectively). βNF induced CYP1A and CYP1C1 (26- and 2.5-fold), while, under conditions used, indigo tended to induce only CYP1A (1.9-fold). The extent of CYP1 induction by PCB126 and βNF was positively correlated to the number of putative dioxin response elements 0-20 kb upstream of the start codons. No morphological effect was observed in tadpoles exposed to 1 nM-10 μM PCB126 at two days post-fertilization (dpf) and screened 20 days later. However, in 14-dpf tadpoles a slight up-regulation of the genes for PCNA, transthyretin, HSC70, Cu-Zn SOD, and Cox-2 was observed two days after exposure to 1 μM PCB126. This study of the full suite of CYP1 genes in an amphibian species reveals gene- and AHR agonist-specific differences in response, as well as a much lower sensitivity to CYP1 induction and short-term toxicity by PCB126 compared with in fish larvae. The single genes in each CYP1 subfamily may make X. tropicalis a useful model for mechanistic studies of CYP1 functions.     

类风湿关节炎患者血清转甲状腺素蛋白化学修饰的蛋白质组学分析

目的通过检测类风湿关节炎（RA）患者血清转甲状腺素蛋白（TTR）的化学修饰类型和含量,探讨其在RA早期诊断中的潜在作用。方法采用酶联免疫吸附试验（ELISA）测定39名RA患者[早期（〈1年）16例,中晚期（〉2年）23例]、20名骨性关节炎（OA）患者及20名健康体检者血清TTR含量;采用Western blot测定血清TTR分子聚合体比例;采用基质辅助激光解吸离子化飞行时间质谱（MALDI-TOF-MS）技术鉴定血清中TTR蛋白的化学修饰类型和比例。结果 RA早期患者血清TTR含量为（502.46±109.25）mg/L,明显高于正常对照组[（424.98±118.52）mg/L]（P〈0.05）;RA中晚期患者[（440.67±94.15）mg/L]也有增高趋势,但与正常对照组比较差异无统计学意义（P=0.733）;OA组TTR含量为（363.91±106.41）mg/L,与正常对照组比较差异无统计学意义（P=0.072）。血清TTR化学修饰有4种蛋白峰：质荷比（m/z）13 749.86±1.48、m/z 13 829.63±2.76、m/z 13 870.70±2.70、m/z 13 927±5.77,分别对应野生型TTR（native TTR）、磺化TTR（sul-TTR）、半胱氨酰化TTR（cys-TTR）和半胱氨酰甘氨酰化TTR（cysgly-TTR）,且TTR修饰比例随病程发生变化。结论 RA患者血清TTR质谱分析发现4个TTR蛋白峰,且修饰比例随病程不同而发生改变;早期RA患者血清TTR含量增加,血清TTR水平有可能作为RA早期诊断的潜在指标。     

Transthyretin mutations in health and disease

To date, over 40 different mutations in transthyretin (TTR) have been associated with amyloid deposition. The major unresolved problem is the correlation between the clinical heterogeneity and the genetic heterogeneity. For instance, whereas some mutations produce neuropathy and some give rise to cardiomyopathy, others produce vitreous opacities, the vast majority being neuropathic. Moreover, some mutations are not amyloidogenic but are responsible to hyperthyroxinemias (by virtue of the protein function in thyroid transport), whereas others are apparently nonpathogenic. The study of TTR variants is very important to the understanding of the amyloid formation process and to establish a relationship between the structure and function of the molecule. The results of current TTR mutation screening programs and their characterization are summarized. © 1995 Wiley-Liss, Inc.