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ObjectiveTurner Syndrome is associated with several phenotypic conditions associated with a higher risk of subsequent comorbidity. We aimed to evaluate the prevalence of congenital malformations and the occurrence of age-related comorbid conditions and to determine whether the frequencies of congenital and acquired conditions depend on X chromosome gene dosage, as a function of karyotype subgroup.Design and methodsThis national retrospective observational cohort study includes 1501 patients. We evaluated the prevalence of congenital malformations and the cumulative incidence of subsequent specific comorbidities at five-year intervals, from the ages of 10 to 30 years, with stratification by karyotype subgroup: 45,X (n = 549), 45,X/46,isoXq (n = 280), 46,X,r(X)/46,XX (n = 106), 45,X/46,XX (n = 221), presence of Y (n = 87).ResultsMedian age was 9.4 (3.7–13.7) years at first evaluation and 16.8 (11.2–21.4) years at last evaluation. Congenital heart (18.9%) malformations were more frequent in 45,X patients, and congenital renal (17.2%) malformations were more frequent in 45,X, 45,X/46,isoXq and 46,X,r(X)/46,XX patients than in those with 45,X/46,XX mosaicism or a Y chromosome (P ConclusionThese data suggest that X gene chromosome dosage, particularly for Xp genes, contributes to the risk of developing comorbidities.

Highlights • In myocardial ischemia, the integrity of the cardiac sarcolemma is severely stressed in the critical earliest moments upon reperfusion. Bolstering sarcolemma integrity improves myocyte survival. • This review focuses on cardiac sarcolemma stability and its role as a therapeutic target in ischemia-reperfusion injury. • Synthetic block copolymers have been shown to interface with the muscle membrane to confer membrane stabilization during stress. • Integrated multidisciplinary research teams, spanning cardiology, physiology, chemistry, and chemical engineering are essential to guide future mechanistic and translational studies of novel chemical-based membrane stabilizers for preserving viable heart muscle during ischemia-reperfusion injury in human patients., Summary The phospholipid bilayer membrane that surrounds each cell in the body represents the first and last line of defense for preserving overall cell viability. In several forms of cardiac and skeletal muscle disease, deficits in the integrity of the muscle membrane play a central role in disease pathogenesis. In Duchenne muscular dystrophy, an inherited and uniformly fatal disease of progressive muscle deterioration, muscle membrane instability is the primary cause of disease, including significant heart disease, for which there is no cure or highly effective treatment. Further, in multiple clinical forms of myocardial ischemia-reperfusion injury, the cardiac sarcolemma is damaged and this plays a key role in disease etiology. In this review, cardiac muscle membrane stability is addressed, with a focus on synthetic block copolymers as a unique chemical-based approach to stabilize damaged muscle membranes. Recent advances using clinically relevant small and large animal models of heart disease are discussed. In addition, mechanistic insights into the copolymer-muscle membrane interface, featuring atomistic, molecular, and physiological structure-function approaches are highlighted. Collectively, muscle membrane instability contributes significantly to morbidity and mortality in prominent acquired and inherited heart diseases. In this context, chemical-based muscle membrane stabilizers provide a novel therapeutic approach for a myriad of heart diseases wherein the integrity of the cardiac muscle membrane is at risk., Central Illustration

The scientific premise, design, and structure-function analysis of chemical-based muscle membrane stabilizing block copolymers are reviewed here for applications in striated muscle membrane injury. Synthetic block copolymers have a rich history and wide array of applications from industry to biology. Potential for discovery is enabled by a large chemical space for block copolymers, including modifications in block copolymer mass, composition, and molecular architecture. Collectively, this presents an impressive chemical landscape to leverage distinct structure-function outcomes. Of particular relevance to biology and medicine, stabilization of damaged phospholipid membranes using amphiphilic block copolymers, classified as poloxamers or pluronics, has been the subject of increasing scientific inquiry. This review focuses on implementing block copolymers to protect fragile muscle membranes against mechanical stress. The review highlights interventions in Duchenne muscular dystrophy, a fatal disease of progressive muscle deterioration owing to marked instability of the striated muscle membrane. Biophysical and chemical engineering advances are presented that delineate and expand upon current understanding of copolymer-lipid membrane interactions and the mechanism of stabilization. The studies presented here serve to underscore the utility of copolymer discovery leading toward the therapeutic application of block copolymers in Duchenne muscular dystrophy and potentially other biomedical applications in which membrane integrity is compromised.

In cardiac muscle, the troponin (cTn) complex is a key regulator of myofilament calcium sensitivity because it serves as a molecular switch required for translating myocyte calcium fluxes into sarcomeric contraction and relaxation. Studies of several species suggest that ectotherm chordates have myofilaments with heightened calcium responsiveness. However, genetic polymorphisms in cTn that cause increased myofilament sensitivity to activating calcium in mammals result in cardiac disease including arrhythmias, diastolic dysfunction, and increased susceptibility to sudden cardiac death. We hypothesized that specific residue modifications in the regulatory arm of troponin I (TnI) were critical in mediating the observed decrease in myofilament calcium sensitivity within the mammalian taxa. We performed large-scale phylogenetic analysis, atomic resolution molecular dynamics simulations and modeling, and computational alanine scanning. This study provides evidence that a His to Ala substitution within mammalian cardiac TnI (cTnI) reduced the thermodynamic potential at the interface between cTnI and cardiac TnC (cTnC) in the calcium-saturated state by disrupting a strong intermolecular electrostatic interaction. This key residue modification reduced myofilament calcium sensitivity by making cTnI molecularly untethered from cTnC. To meet the requirements for refined mammalian adult cardiac performance, we propose that compensatory evolutionary pressures favored mutations that enhanced the relaxation properties of cTn by decreasing its sensitivity to activating calcium.

Muscle membrane vulnerability is a hallmark of Duchenne Muscular Dystrophy (DMD), an X-linked disease that results in progressive skeletal muscle weakness and cardiomyopathy. Cardiac disease is an increasing cause of death in DMD and there is currently no cure for DMD. One unique therapeutic approach is the use of membrane sealants to protect the fragile dystrophic muscle membranes from mechanical stress. We propose a structure-function strategy in understanding the mechanism by which block copolymers may protect dystrophic cardiac and skeletal muscles. Poloxamer 188 (P188) is a membrane sealant that has been shown by us and others to protect the fragile dystrophic myocardium under physiological stress but appears to have reduced efficacy in affecting the skeletal myopathy. P188 belongs to the tri-block copolymer family, which comprises molecules made of a hydrophobic polypropylene oxide (PPO) core flanked by hydrophilic chains of polyethylene oxide (PEO) moieties. These copolymers exist at various molecular weights and PPO to PEO ratios and it is unknown what structural properties of P188 confer its membrane protecting functionality. Mechanistic knowledge is requisite for a deeper understanding of muscle membrane protection by copolymer sealants to enable therapeutic application. Interestingly, our data shows that P188 is efficacious in isolated dystrophic skeletal myofibers suggesting that poor delivery and low diffusion into the core of dystrophic whole muscle in vivo limits P188 effectiveness. Ultimately, fully effective therapeutic strategies must simultaneously target both cardiac and skeletal muscle tissues. We will present data on copolymer structure-function understanding and discuss how these new data will shed light into the structural requisite for more efficacious and potent membrane sealants for dystrophic skeletal muscle in vivo.

Troponin I (TnI) has a central, isoform-dependent role in ischemic contractile failure. The fetal heart expresses the slow skeletal TnI (ssTnI) isoform which confers protection from ischemia-mediated contractile failure relative to the adult expressed cardiac TnI (cTnI) isoform. A single codon substitution in cTnI, A164H, reverts significantly to an ssTnI phenotype, in specifics, conferring protection from ischemia-mediated contractile failure. Importantly, unlike ssTnI, cTnI A164H does not alter contractile performance under baseline conditions. The molecular mechanisms for the marked enhancement in myocyte function under pathophysiological conditions with no detected effects under baseline conditions have yet to be determined. Isoform specific residues in helix 4 of TnI were investigated through structure/function analysis to gain insight into this mechanism. Molecular dynamics simulation for cTnI, Q157R/A164H/E166V/H173N cTnI (QAEH), A164H cTnI, and ssTnI in complex with cTnC, showed that substitution of cTnI with the ssTnI residues alters the intermolecular interactions between TnI and cTnC. These findings suggest that these residues are important for the conformation of helix 4 in regards to cTnC. To investigate if these substitutions alter function, adult cardiac myocytes were transduced with adenovirus expressing QAEH cTnI and sarcomere dynamics were analyzed. QAEH cTnI showed a similar phenotype to ssTnI, increasing sarcomere shortening and slowing relaxation at pH 7.4 while maintaining normal contractile function under acidic conditions. To elucidate this further, double and triple mutants were analyzed to determine the importance of each of the three residues to baseline contractility. The data show that H173 and Q157 are necessary for the reduced contractility at baseline while E166 exerts the opposite effect. Taken together, these new findings suggests that the conformation of helix 4 in TnI is an important determinate of contractility in ischemia.

Duchenne muscular dystrophy (DMD) is a fatal disease of striated muscle deterioration. A unique therapeutic approach for DMD is the use of synthetic membrane stabilizers to protect the fragile dystrophic sarcolemma against contraction-induced mechanical stress. Block copolymer-based membrane stabilizer poloxamer 188 (P188) has been shown to protect the dystrophic myocardium. In comparison, the ability of synthetic membrane stabilizers to protect fragile DMD skeletal muscles has been less clear. Because cardiac and skeletal muscles have distinct structural and functional features, including differences in the mechanism of activation, variance in sarcolemma phospholipid composition, and differences in the magnitude and types of forces generated, we speculated that optimized membrane stabilization could be inherently different. Our objective here is to use principles of pharmacodynamics to evaluate membrane stabilization therapy for DMD skeletal muscles. Results show a dramatic differential effect of membrane stabilization by optimization of pharmacodynamic-guided route of poloxamer delivery. Data show that subcutaneous P188 delivery, but not intravascular or intraperitoneal routes, conferred significant protection to dystrophic limb skeletal muscles undergoing mechanical stress in vivo. In addition, structure-function examination of synthetic membrane stabilizers further underscores the importance of copolymer composition, molecular weight, and dosage in optimization of poloxamer pharmacodynamics in vivo.

Muscle membrane vulnerability is a hallmark of Duchenne Muscular Dystrophy (DMD), an X-linked neuromuscular disease that results in progressive skeletal muscle weakness and significant cardiomyopathy. We propose the use of membrane-sealant copolymers as an innovative and unique potential therapeutic for DMD. The tri-block copolymer family comprises molecules made of a hydrophobic polypropylene oxide (PPO) core flanked bilaterally by linear chains of hydrophilic polyethylene oxide (PEO) chemical moieties. Block copolymers exist at various molecular weights and PPO/PEO ratios and it is currently not known what structural properties confer membrane sealing capacity to copolymers of this family. We and other groups have shown that one such sealant, poloxamer P188, protects dystrophic hearts in vitro and in vivo in both small and large animal models of DMD but its apparent efficacy is significantly reduced in skeletal muscle in vivo. This underscores the importance of discovering more potent membrane sealants to treat all striated muscles in DMD. We have initiated a collaborative structure-function approach by implementing and refining an in vitro membrane injuring osmotic and shear stress assay to analyze the membrane sealing functions of these tri-block copolymer family members on dystrophic skeletal muscle to systematically determine the effects of PPO/PEO ratio and molecular weight on membrane protection. We will present progress on copolymer structure-function understanding and discuss how these new data will shed light into the structural requisite for more efficacious and potent membrane sealants.

Computerized axial tomographic scans (CAT scans) of thorax and abdomen were used as part of the initial staging procedure of 50 consecutive patients with small-cell bronchogenic carcinoma (SCBC). The aims were to define the extent of the primary tumor and metastatic spread, and to compare the information obtained from CAT scans with conventional staging procedures. With CAT scanning, spread of the primary tumor was found to be far more extensive than originally believed when defined by conventional assessment. Of 35 patients conventionally staged as localized T1 or T2 tumors, 27 (77%) had their stage increased to extensive T3 disease. similarly, subcarinal lymph nodes were found in one patient when conventional methods were used (2%), but 16 patients (32%) were found when CAT scan was used. Unsuspected adrenal metastases were found in eight patients (16%) and retrocrural nodes in four patients (8%). Thirty-seven patients (74%) were found to have Stage III tumors when conventional staging was used; 47 patients (94%) were found to be Stage III following CAT scanning, demonstrating that, within the thorax, localized tumors are very uncommon. CAT scanning demonstrates the degree of intrathoracic spread very clearly, and has a valuable role in the initial investigation of patients with SCBC if the planned treatment includes radiotherapy.

The clinical outcomes of seven girls presenting with pseudosexual precocity caused by isolated autonomous ovarian follicular cysts are presented. Six of the seven girls, aged 11 months to 6.9 years, had a unilateral ovarian cyst detected by ultrasound at the first acute episode. Plasma oestradiol was raised in only five of the cases, but all had a low response to luteinising hormone releasing hormone stimulation. Follow up lasted for up to eight years with recurrent episodes of variable frequency and severity in all seven patients. Evidence of McCune-Albright syndrome appeared later in only three patients. It could not be predicted from the initial symptoms or the clinical course. Mutations of the G(s)alpha protein leading to activation were investigated in the lymphocytes and ovarian and bone tissues of four patients. Only one patient showed a mutation in bone tissue. Close follow up with repeated searches for skeletal lesions remains necessary since the distribution of somatic mutations cannot be assessed by molecular studies. Most patients with recurrent ovarian cysts require a conservative approach.