Kinetics of Wnt-driven beta-catenin stabilization revealed by quantitative and temporal imaging

The Wnt/beta-catenin signal transduction pathway regulates a broad range of developmental processes. Aberrant activation of the Wnt pathway leads to cancer and degenerative diseases. beta-catenin is a key signaling molecule that is frequently used as a direct monitor of Wnt pathway activation. This paper describes a multi-parametric method for quantitative analysis of cellular beta-catenin protein levels in a rapid and high-throughput manner. The assay offers temporally resolved detection of Wnt-stimulated accumulation of beta-catenin, simultaneously detecting cell number, and it sheds light onto the kinetics of posttranslational stabilization of beta-catenin.     

The prevalence of consanguineous marriages in an underserved area in Lebanon and its association with congenital anomalies

Background: Consanguinity is a recognized common practice among marriages in the Middle East. Many studies have suggested a strong association between first cousin marriages and the incidence of autosomal recessive diseases and congenital anomalies. The objectives of this study were to study the prevalence of consanguinity among the marriages of Bekaa (a region in Lebanon) with its sociodemographic correlates, and to assess the prevalence of congenital anomalies associated with these marriages. Methods: This study was a cross-sectional study done in three of the major areas of the Bekaa region. The sample size consisted of 552 households chosen based on proportionate random sampling according to population size in each area. The survey was conducted based on face-to-face interview with a member of the couples of each household. Results: The overall prevalence of consanguineous marriages was reported to be 42% with first cousin marriage constituting around 31% of the total marriages. No association was found between different socioeconomic status (SES) correlates and first cousin marriages. Results showed a significant association between first cousin marriage and mental retardation, physical retardation, bilateral cleft lip +/- cleft palate, cystic fibrosis, and congenital blindness. Conclusion: In a population with a high degree of inbreeding, the formulation of a public health program with multiapproach strategy, including education about the anticipated genetic consequences, prenatal diagnosis, neonatal screening, and genetic counseling, is a necessity.     

Bilateral transverse sinus thrombosis secondary to a homozygous C677T MTHFR gene mutation

We describe the case of a previously healthy young man who presented with headache, diplopia, nausea, vomiting, and bilateral papilledema. Magnetic resonance venography of the brain revealed thrombosis of the right transverse sinus. Blood tests showed elevated homocysteine levels, and coagulation studies revealed a homozygous C677T mutation and a heterozygous A1298C mutation of the methylenetetrahydrofolate reductase (MTHFR) gene. The patient had no other etiology for venous thrombosis. We recommend screening patients who present with sinus thrombosis for MTHFR gene mutations.     

4-Aminopyrimidine tetrahydronaphthols: a series of novel vanilloid receptor-1 antagonists with improved solubility properties

8-(6-(4-(Trifluoromethyl)phenyl)pyrimidin-4-ylamino)-1,2,3,4-tetrahydronaphthalen-2-ol (4) and analogs (5-10) were shown to be potent inhibitors of human and rat TRPV1 in vitro with increased solubility over our previous series. Synthesis, SAR, and improvements in metabolic stability and absorption of these compounds are described herein.     

Design and synthesis of 6-phenylnicotinamide derivatives as antagonists of TRPV1

6-Phenylnicotinamide (2) was previously identified as a potent TRPV1 antagonist with activity in an in vivo model of inflammatory pain. Optimization of this lead through modification of both the biaryl and heteroaryl components has resulted in the discovery of 6-(4-fluorophenyl)-2-methyl-N-(2-methylbenzothiazol-5-yl)nicotinamide (32; SB-782443) which possesses an excellent overall profile and has been progressed into pre-clinical development.     

The interplay between vaccination and social distancing strategies affects COVID19 population-level outcomes

Social distancing is an effective population-level mitigation strategy to prevent COVID19 propagation but it does not reduce the number of susceptible individuals and bears severe social consequences—a dire situation that can be overcome with the recently developed vaccines. Although a combination of these interventions should provide greater benefits than their isolated deployment, a mechanistic understanding of the interplay between them is missing. To tackle this challenge we developed an age-structured deterministic model in which vaccines are deployed during the pandemic to individuals who do not show symptoms. The model allows for flexible and dynamic prioritization strategies with shifts between target groups. We find a strong interaction between social distancing and vaccination in their effect on the proportion of hospitalizations. In particular, prioritizing vaccines to elderly (60+) before adults (20-59) is more effective when social distancing is applied to adults or uniformly. In addition, the temporal reproductive number R_t is only affected by vaccines when deployed at sufficiently high rates and in tandem with social distancing. Finally, the same reduction in hospitalization can be achieved via different combination of strategies, giving decision makers flexibility in choosing public health policies. Our study provides insights into the factors that affect vaccination success and provides methodology to test different intervention strategies in a way that will align with ethical guidelines.     

<Emphasis Type="Italic">MEFV</Emphasis> gene mutations spectrum among Lebanese patients referred for Familial Mediterranean Fever work-up: Experience of a major tertiary care center

Familial Mediterranean Fever (FMF) is an autosomal recessive inflammatory disorder predominantly affecting people living in or originating from areas around the Mediterranean Sea, mainly Jews, Armenians, Turks, and Arabs. It is characterized by recurrent attacks of inflammation of serosal membranes and fever resulting in acute abdominal, chest, or joint pain. Over 50 MEditerranean FeVer (MEFV) mutations and polymorphisms have been identified in FMF patients. The objective of this study was to analyze the distribution and frequencies of 12 MEFV mutations in 266 referred Lebanese patients using a reverse-hybridization assay. Of the 266 patients, 129 (48.5%) were positive for at least one mutation and 137 (51.5%) had no mutations detected. Of the 129 patients with mutations, 35 were homozygous, 41 were compound heterozygous and 53 were heterozygous. The five most common mutations M694V, E148Q, V726A, M694I and M680I (G/C) accounted for 26.1, 22.2, 21.3, 9.6 and 7.7%, respectively. The A744S, F479L, R761H and I692del were encountered in 2.9% of patients; P369S and M680I (G/A) were found in 1.2% of patients while K695R was absent. The spectrum of the MEFV mutations among our sampled Lebanese FMF patients shows the high heterogeneity at the allelic level when compared to Arab and non-Arab populations. The most important feature was the relatively high frequency of the E148Q in our study group that allows us to question it as a mutation rather than a polymorphism. Further studies should be conducted to evaluate the role of the E148Q allele.     

Frequency distribution of the <Emphasis Type="Italic">G/A</Emphasis> alleles of the β-fibrinogen gene in the Lebanese population

Fibrinogen is a plasma protein that has been reported to be associated with an increased risk of atherothrombotic diseases and venous thrombosis. The most common polymorphism that has been studied so far in different populations is the G-455-->A polymorphism in the promoter region of the beta-fibrinogen gene. We studied 160 healthy unrelated Lebanese individuals for the prevalence of -455G/G, -455G/A and -455A/A genotypes of the beta-fibrinogen gene and the frequency of G and A alleles using a reverse hybridization PCR assay. The prevalence of the G/G, G/A, and A/A genotypes were found to be 60.6, 31.9 and 7.5%, respectively. The frequency of the G and A alleles were found to be 0.77 and 0.23, respectively. As compared to other ethnic groups, the Lebanese individuals were found to have a relatively high prevalence of the A allele which may predispose them to develop cardiovascular diseases as well as thrombotic events. This study provides additional unique genetic information pertaining to the Lebanese population.     

Cardiac magnetic resonance imaging of myocardial contrast uptake and blood flow in patients affected with idiopathic or familial dilated cardiomyopathy

Idiopathic dilated cardiomyopathy (IDC) is characterized by left ventricular (LV) enlargement with systolic dysfunction, other causes excluded. When inherited, it represents familial dilated cardiomyopathy (FDC). We hypothesized that IDC or FDC would show with cardiac magnetic resonance (CMR) increased myocardial accumulation of gadolinium contrast at steady state and decreased baseline myocardial blood flow (MBF) due to structural alterations of the extracellular matrix compared with normal myocardium. CMR was performed in nine persons affected with IDC/FDC. Healthy controls came from the general population (n = 6) or were unaffected family members of FDC patients (n = 3) without signs or symptoms of IDC/FDC or any structural cardiac abnormalities. The myocardial partition coefficient for gadolinium contrast (lambda(Gd)) was determined by T1 measurements. LV shape and function and MBF were assessed by standard CMR methods. lambda(Gd) was elevated in IDC/FDC patients vs. healthy controls (lambda(Gd) = 0.56 +/- 0.15 vs. 0.41 +/- 0.06; P = 0.002), and correlated with LV enlargement (r = 0.61 for lambda(Gd) vs. end-diastolic volume indexed by height; P < 0.01) and with ejection fraction (r = -0.80; P < 0.001). The extracellular volume fraction was higher in IDC patients than in healthy controls (0.31 +/- 0.05 vs. 0.24 +/- 0.03; P = 0.002). Resting MBF was lower in IDC patients (0.64 +/- 0.13 vs. 0.91 +/- 0.22; P = 0.01) than unaffected controls and correlated with both the partition coefficient (r = -0.57; P = 0.012) and the extracellular volume fraction (r = -0.56; P = 0.019). The expansion of the extracellular space correlated with reduced MBF and ventricular dilation. Expansion of the extracellular matrix may be a key contributor to contractile dysfunction in IDC patients.     

Importance of collagen orientation and depth-dependent fixed charge densities of cartilage on mechanical behavior of chondrocytes

The collagen network and proteoglycan matrix of articular cartilage are thought to play an important role in controlling the stresses and strains in and around chondrocytes, in regulating the biosynthesis of the solid matrix, and consequently in maintaining the health of diarthrodial joints. Understanding the detailed effects of the mechanical environment of chondrocytes on cell behavior is therefore essential for the study of the development, adaptation, and degeneration of articular cartilage. Recent progress in macroscopic models has improved our understanding of depth-dependent properties of cartilage. However, none of the previous works considered the effect of realistic collagen orientation or depth-dependent negative charges in microscopic models of chondrocyte mechanics. The aim of this study was to investigate the effects of the collagen network and fixed charge densities of cartilage on the mechanical environment of the chondrocytes in a depth-dependent manner. We developed an anisotropic, inhomogeneous, microstructural fibril-reinforced finite element model of articular cartilage for application in unconfined compression. The model consisted of the extracellular matrix and chondrocytes located in the superficial, middle, and deep zones. Chondrocytes were surrounded by a pericellular matrix and were assumed spherical prior to tissue swelling and load application. Material properties of the chondrocytes, pericellular matrix, and extracellular matrix were obtained from the literature. The loading protocol included a free swelling step followed by a stress-relaxation step. Results from traditional isotropic and transversely isotropic biphasic models were used for comparison with predictions from the current model. In the superficial zone, cell shapes changed from rounded to elliptic after free swelling. The stresses and strains as well as fluid flow in cells were greatly affected by the modulus of the collagen network. The fixed charge density of the chondrocytes, pericellular matrix, and extracellular matrix primarily affected the aspect ratios (height/width) and the solid matrix stresses of cells. The mechanical responses of the cells were strongly location and time dependent. The current model highlights that the collagen orientation and the depth-dependent negative fixed charge densities of articular cartilage have a great effect in modulating the mechanical environment in the vicinity of chondrocytes, and it provides an important improvement over earlier models in describing the possible pathways from loading of articular cartilage to the mechanical and biological responses of chondrocytes.