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Transthyretin (TTR) tetramer dissociation is rate limiting for aggregation and subunit exchange. Slowing of TTR tetramer dissociation via kinetic stabiliser binding slows cardiomyopathy progression. Quadruplicate subunit exchange comparisons of the drug candidate AG10, and the drugs tolcapone, diflunisal, and tafamidis were carried out at 1, 5, 10, 20 and 30 µM concentrations in 4 distinct pooled wild type TTR (TTRwt) human plasma samples. These experiments reveal that the concentration dependence of the efficacy of each compound at inhibiting TTR dissociation was primarily determined by the ratio between the stabiliser's dissociation constants from TTR and albumin, which competes with TTR to bind kinetic stabilisers. The best stabilisers, tafamidis (80 mg QD), AG10 (800 mg BID), and tolcapone (3 x 100 mg over 12 h), exhibit very similar kinetic stabilisation at the plasma concentrations resulting from these doses. At a 10 µM plasma concentration, AG10 is slightly more potent as a kinetic stabiliser vs. tolcapone and tafamidis (which are similar), which are substantially more potent than diflunisal. Dissociation of TTR can be limited to 10% of its normal rate at concentrations of 5.7 µM AG10, 10.3 µM tolcapone, 12.0 µM tafamidis, and 188 µM diflunisal. The potency similarities revealed by our study suggest that differences in safety, adsorption and metabolism, pharmacokinetics, and tissue distribution become important for kinetic stabiliser clinical use decisions. [ABSTRACT FROM AUTHOR]

Background:Wild-type transthyretin amyloidosis (ATTRwt) is an age-related life-threatening condition. Prognosis is mainly dependent on cardiac involvement. Other organs and tissues may be affected. Their early recognition may increase awareness of physicians and positively affects the prognosis. Presbycusis is another age-related disorder. Whether this disease is associated to ATTRwt amyloidosis is unknown. Methods:Sixteen consecutive patients with confirmed diagnosis of ATTRwt amyloidosis at the Mondor Amyloidosis Network, France, underwent otoscopy and audiological tests including pure tone audiometry, speech reception threshold and speech discrimination score. Results:The mean age was 79 ± 5 years. All were male with an NYHA average of 2.5 ± 0.8. All the patients had sensorineural hearing loss that seemed to preexist to cardiac disorder with greater severity than expected for their age. For speech discrimination test, the mean speech reception threshold was 28 ± 15 dB and the mean speech discrimination score was 68 ± 16 at 40 dB. Ten patients (62.5%) failed to recognize 100% of the words. Compared to age-related expectations according to statistical distribution (ISO), hearing loss included all frequencies and was more severe in patients with ATTRwt amyloidosis. Conclusions:These findings suggest that amyloid deposits could infiltrate the various anatomical structures of the inner ear. Description of specific audiologic pattern of ATTRwt amyloidosis might be proposed as a “red flag” and could help for early identification of patients who may be at high risk of ATTRwt amyloidosis as specific treatments are available. [ABSTRACT FROM AUTHOR]

Background: Systemic wild-type ATTR (ATTRwt) amyloidosis is a prevalent aging-related disorder. However, a limited number of systemic ATTRwt amyloidosis patients have been diagnosed antemortem, and therefore, the prevalence of ATTRwt is underestimated. Here, we investigated clinical findings of a series of systemic ATTRwt amyloidosis patients with antemortem diagnosis. Methods: Thirty-one consecutive patients diagnosed with systemic ATTRwt amyloidosis at Shinshu University Hospital were included in this study. Systemic ATTRwt amyloidosis was diagnosed based on proven ATTR amyloid deposition in biopsy specimens and confirmation of wild-type TTR genotype. Results: The systemic ATTRwt amyloidosis patients consisted of 24 men and seven women, and mean age of onset was 69.8 ± 9.0 years. The most common initial symptom was carpal tunnel syndrome (CTS, 17 patients), followed by heart failure symptoms (14 patients). The mean age at diagnosis was 74.5 ± 8.3 years and the duration of illness from onset to diagnosis was 5.4 ± 4.4 years. Cardiogenic embolism and renal dysfunction are also frequently seen during the course of the disease. Conclusions: CTS is the most common initial symptom of systemic ATTRwt amyloidosis. Our results suggest the possibility of systemic ATTRwt amyloidosis diagnosis at an early stage by carefully examining patients with CTS. [ABSTRACT FROM PUBLISHER]

Objective: A nationwide survey on systemic wild-type ATTR (ATTRwt) amyloidosis was conducted to elucidate the frequency, clinical picture and possible diagnostic issues of ATTRwt amyloidosis in Japan. Methods: A questionnaire was sent to 4629 clinical departments across Japan. A total of 2341 (50.6%) responses were returned completed for further analysis. Results: Fifty-one patients with ATTRwt amyloidosis (82% male) were identified between January 2012 and December 2014. The study subjects were identified in 11 departments at 10 institutes. The mean age of onset and diagnosis were 71.6 and 73.6 years, respectively. The main clinical findings were cardiac failure (76%), cardiac conduction defects/arrhythmia (59%), renal dysfunction (49%), carpal tunnel syndrome (45%) and spinal canal stenosis (22%). Conclusions: ATTRwt amyloidosis is diagnosed in a limited number of institutes in Japan and is therefore considered to be underdiagnosed. [ABSTRACT FROM AUTHOR]

Placebo-controlled clinical trials are useful for identifying the dose of a drug candidate that produces a meaningful clinical response in a patient population. Currently, Pfizer, Inc. is enrolling a 400-person clinical trial to test the efficacy of 20 or 80 mg of tafamidis to ameliorate transthyretin (TTR)-associated cardiomyopathy using clinical endpoints. Herein, we provide guidance for how to optimize the dose of tafamidis for each WT TTR cardiomyopathy patient using its mechanism of action as the key readout, i.e. we identify the dose of tafamidis that maximally kinetically stabilizes TTR in the blood. Tetramer dissociation is rate limiting for TTR aggregation, which appears to drive the pathology of the TTR amyloidoses. Hence, we measure the TTR tetramer dissociation rate (kinetic stability) in the patient's plasma as a function of tafamidis dose to optimize the dose employed to maximize kinetic stability. Historical data tell us that a subset of patients exhibiting higher tafamidis plasma concentrations are maximally kinetically stabilized at the 20-mg tafamidis dose, whereas the patient studied herein required a 60 mg once daily dose to achieve maximum kinetic stabilization. We anticipate that establishing the dose of tafamidis that achieves maximal TTR kinetic stabilization will translate into a maximal clinical effect, but that remains to be demonstrated. [ABSTRACT FROM AUTHOR]

Systemic amyloidosis is caused by extracellular deposition of insoluble fibrillar proteins arranged in β-pleated sheets. [11C]PIB has been used in PET studies to assess Aβ deposition in brain of patients with Alzheimer's disease (AD). The possibility to visualize other types of amyloid deposits with [11C]PIB would be of potential clinical importance in early diagnosis and for following therapeutic effects. In the present study, we evaluated in vitro binding of [3H]PIB to tissues containing transthyretin (ATTR), immunoglobulin light-chain (AL), amyloid protein A (AA) and Aβ amyloid. We found significantly higher binding of [3H]PIB in tissue from systemic amyloidoses than in control tissue, i.e. 4.7 times higher ( p < 0.05). [3H]PIB showed the highest affinity to cortex of AD brain (IC50 = 3.84 nM), while IC50 values were much higher for ATTR, AA and AL type of amyloidosis and large variations in affinity were observed even within tissues having the same type of amyloidosis. Extraction with guanidine-HCl, which disrupts the β-sheet structure, decreased the protein levels and, concomitantly, the binding of [3H]PIB in all four types of amyloidoses. [ABSTRACT FROM AUTHOR]

Objective: To investigate histological features of deposited amyloid in the synovial tissue and its clinical significance in knee joint osteoarthritis (OA) patients. Methods: We prospectively enrolled 232 consecutive patients who underwent arthroplasty or total replacement of the knee joint for treatment of OA. Congo red staining and immunohistochemistry were performed in the synovial tissue obtained at surgery. When transthyretin (TTR)-derived amyloid was positive, we analyzed all 4 exons of the TTR gene using the direct DNA sequencing method in order to detect mutations. Results: We analyzed 322 specimens in this study. Twenty-six specimens (8.1%) obtained from 21 patients (5 men and 16 women; mean, 79.0 ± 4.6 years) showed deposition of amyloid, which was positively stained with the anti-TTR antibody. Eighteen patients showed inhomogeneous accumulations of amyloid in the loose connective tissue under the synovial epithelia sometimes with nodule formation, while in the remaining three, small vessels in the adipose tissue were involved. Medical records of these patients revealed nothing remarkable in the clinical course, laboratory data or macroscopic intraarticular findings at surgery. No mutations were detectable in the TTR gene analysis. Conclusion: Wild-type TTR-derived amyloid may affect the synovial tissue as a result of long-term mechanical stress or as a part of senile systemic amyloidosis in approximately 8% of knee joint OA patients. No obvious clinical significance was found in synovial deposition of amyloid. [ABSTRACT FROM AUTHOR]

We describe a rare complication, systemic arterial thromboembolism, seen in two patients with senile systemic amyloidosis (SSA). Case 1 was a 73-year-old man who was tentatively diagnosed as having cardiac amyloidosis. Five months later, he was afflicted by severe left flank pain. CT disclosed renal infarction and then he received endomyocardial biopsy and the transthyretin (TTR) gene analysis, leading to the final diagnosis of SSA. Case 2 was an 88-year-old woman who had been definitively diagnosed as having SSA-related heart failure with atrial fibrillation two years before. She was transferred to the emergency room in our hospital and enhanced CT revealed complete occlusions of the left internal carotid and left vertebral arteries, both subclavian arteries, and the left renal and left internal iliac arteries. Paying much attention to intracardiac thrombosis might be necessary in taking care of SSA patients. [ABSTRACT FROM AUTHOR]

Spinal amyloidosis can occur as a part of systemic amyloidosis or as localized amyloidomas. However, the exact pathogenesis of the spinal amyloidosis remains to be fully understood. Transthyretin (TTR) is an amyloidogenic protein causing two kinds of amyloid diseases. One is senile systemic amyloidosis (SSA), which is caused by wild-type (WT) TTR and primarily affects cardiac functions. The other type is familial amyloidosis, which is mainly induced by mutated TTR. We report here the first case of multifocal spinal TTR amyloidosis derived from WT TTR with radiculomyelopathy and destructive spondylosis. The data and clinical manifestations suggest that the patient may develop SSA. Clinical manifestations of TTR-related amyloidosis may vary more than we previously thought. In spinal amyloidosis, WT TTR is one of the candidate precursor proteins for the disease. [ABSTRACT FROM AUTHOR]

Two male patients aged 72 and 77 were found to have transthyretin (TTR) immunoreactive amyloid deposits in their gastrointestinal tracts when they underwent surgery for gastric and sigmoid colon cancer, respectively. They had no cardiac symptoms and there was no mutation in their TTR gene. Amyloid deposits were seen mainly on vascular walls in submucosal layers of the stomach and colon, while the muscularis mucosae, which is invariably affected in familial amyloid polyneuropathy (FAP), was completely free of amyloid deposition. The pattern of TTR-derived amyloid deposition in the gastrointestinal tract in SSA and in FAP are quite different. [ABSTRACT FROM AUTHOR]

Serum transthyretin (TTR) levels are reduced in familial amyloidotic polyneuropathy (FAP). A single study of patients with senile systemic amyloidosis (SSA) in Sweden found that those individuals also had a significantly lower mean serum TTR concentration than age- and gender-matched controls. To determine if the same phenomenon prevailed in an ethnically more heterogeneous population, we compared the serum TTR levels, as determined by ELISA, in 45 documented SSA patients with congestive heart failure, 20 AL patients with congestive heart failure and population controls. Serum TTR concentrations in the controls were influenced in a statistically significant manner by age, gender and ethnicity. Although it is unlikely that such differences are clinically relevant, they must be considered when assessing the meaning of serum TTR concentrations in any clinically defined population. The serum concentrations in patients with SSA did not differ from age, gender and ethnically matched controls or from a group of AL patients with significant clinical cardiac involvement. We also compared TTR concentrations in 12 African-Americans carrying the TTR V122I allele with those in 826 African-Americans who were homozygous wild type at the TTR locus. The TTR V122I carriers had significantly lower serum TTR concentrations than appropriate controls even though the majority of such individuals had not reached the age of clinical or anatomic risk, i.e. over 60. Thus, as in carriers of other TTR mutations the serum TTR level is lower than normal, despite having a much later appearance of clinical disease. [ABSTRACT FROM AUTHOR]

Senile systemic amyloidosis (SSA) and cerebral amyloid angiopathy (CAA) are amyloid disorders, which typically manifest with old age. The aim of our study was to examine the possible association of these disorders in very old Finns. We performed a prospective, population-based post mortem study and used histological and immunohistochemical staining methods to verify the presence of these types of amyloid. All 63 subjects (59% of the 107 individuals 95 years of age or more, who died during the 10-year follow-up study), 53 women and 10 men), had been neurologically examined. The prevalence of SSA and its association with CAA, dementia, and neuropathologically verified AD was analyzed. Overall SSA occurred in 23 (37%) and CAA in 28 (44%) of the 63 subjects. At clinical examination 41 individuals (65%) were demented; 24 (38%) had Alzheimer's disease. SSA showed no association with the presence of CAA (P = 0.45), clinical dementia (P = 0.09), or Alzheimer's disease (P = 0.21), or sex (P = 0.53). Our prospective population based study shows that SSA and CAA are frequent in very old Finns, but they do not associate. [ABSTRACT FROM AUTHOR]

Background: Cardiac amyloidosis had been considered to be an incurable disease; however, new disease-modifying therapeutic approaches have succeeded in ameliorating the disease. Therefore, early and precise diagnosis based on the amyloid precursor protein is extremely important. Objective: To determine the prevalence rates of systemic amyloidoses underlying cardiac amyloidosis. Methods: The types of amyloidosis in 53 consecutive patients with endomyocardial biopsy-proven cardiac amyloidosis were analyzed by Congo red and immunohistochemical staining. If staining for TTR was positive, direct DNA sequencing of the entire TTR gene was performed. Results: ATTR amyloidosis was the most common (32/53 patients, 60.4%). The ATTR amyloidosis subtypes were senile systemic amyloidosis (SSA) 11, familial ATTR 10, and genotype unknown 11. AL amyloidosis was the next most frequent (19/53, 35.8%). Conclusions: ATTR amyloidosis, especially SSA, might be much more common than previously thought. With the development of new drugs targeting the ATTR amyloidosis, major efforts should be made to increase awareness of senile systemic amyloidosis among cardiologists. [ABSTRACT FROM AUTHOR]

Amyloid deposits in the heart derived from transthyretin are commonly seen at autopsy in elderly patients. Massive deposition, causing senile systemic amyloidosis (SSA), is considered to be relatively uncommon and reported series suggest that SSA is considerably less common than amyloid light-chain (AL) amyloidosis. This article reviews the autopsy prevalence of transthyretin-derived cardiac amyloid, addresses whether there is definitive evidence for regional or ethnic differences and argues that the reported prevalence of SSA significantly underrepresents the true prevalence of the disease which may be as common, or commoner, than AL amyloidosis. [ABSTRACT FROM AUTHOR]