A large multicenter cohort on the use of full-thickness resection device for difficult colonic lesions.

BACKGROUND: Introduction of the full-thickness resection device (FTRD) has allowed endoscopic resection of difficult lesions such as those with deep wall origin/infiltration or those located in difficult anatomic locations. The aim of this study is to assess the outcomes of the FTRD among its early users in the USA. METHODS: Patients who underwent endoscopic full-thickness resection (EFTR) for lower gastrointestinal tract lesions using the FTRD at 26 US tertiary care centers between 10/2017 and 12/2018 were included. Primary outcome was R0 resection rate. Secondary outcomes included rate of technical success (en bloc resection), achievement of histologic full-thickness resection (FTR), and adverse events (AE). RESULTS: A total of 95 patients (mean age 65.5 ± 12.6 year, 38.9% F) were included. The most common indication, for use of FTRD, was resection of difficult adenomas (non-lifting, recurrent, residual, or involving appendiceal orifice/diverticular opening) (66.3%), followed by adenocarcinomas (22.1%), and subepithelial tumors (SET) (11.6%). Lesions were located in the proximal colon (61.1%), distal colon (18.9%), or rectum (20%). Mean lesion diameter was 15.5 ± 6.4 mm and 61.1% had a prior resection attempt. The mean total procedure time was 59.7 ± 31.8 min. R0 resection was achieved in 82.7% while technical success was achieved in 84.2%. Histologically FTR was demonstrated in 88.1% of patients. There were five clinical AE (5.3%) with 2 (2.1%) requiring surgical intervention. CONCLUSIONS: Results from this first US multicenter study suggest that EFTR with the FTRD is a technically feasible, safe, and effective technique for resecting difficult colonic lesions.

Sphingosine-1-Phosphate Receptor Modulator, FTY720, Improves Diastolic Dysfunction and Partially Reverses Atrial Remodeling in a Tm-E180G Mouse Model Linked to Hypertrophic Cardiomyopathy.

BACKGROUND: Hypertrophic cardiomyopathy (HCM) is a genetic cardiovascular disorder, primarily involving mutations in sarcomeric proteins. HCM patients present with hypertrophy, diastolic dysfunction, and fibrosis, but there is no specific treatment. The sphingosine-1-phosphate receptor modulator, FTY720/fingolimod, is approved for treatment of multiple sclerosis. We hypothesize that modulation of the sphingosine-1-phosphate receptor by FTY720 would be of therapeutic benefit in sarcomere-linked HCM. METHODS: We treated mice with an HCM-linked mutation in tropomyosin (Tm-E180G) and nontransgenic littermates with FTY720 or vehicle for 6 weeks. Compared with vehicle-treated, FTY720-treated Tm-E180G mice had a significant reduction in left atrial size (1.99±0.19 [n=7] versus 2.70±0.44 [n=6] mm; P<0.001) and improvement in diastolic function (E/A ratio: 2.69±0.38 [n=7] versus 5.34±1.19 [n=6]; P=0.004) as assessed by echocardiography. RESULTS: Pressure-volume relations revealed significant improvements in the end-diastolic pressure volume relationship, relaxation kinetics, preload recruitable stroke work, and ejection fraction. Detergent-extracted fiber bundles revealed a significant decrease in myofilament Ca2+-responsiveness (pCa50=6.15±0.11 [n=13] versus 6.24±0.06 [n=14]; P=0.041). We attributed these improvements to a downregulation of S-glutathionylation of cardiac myosin binding protein-C in FTY720-treated Tm-E180G mice and reduction in oxidative stress by downregulation of NADPH oxidases with no changes in fibrosis. CONCLUSIONS: This is the first demonstration that modulation of S1PR results in decreased myofilament-Ca2+-responsiveness and improved diastolic function in HCM. We associated these changes with decreased oxidative modification of myofilament proteins via downregulation of NOX2. Our data support the hypothesis that modification of sphingolipid signaling may be a novel therapeutic approach in HCM.

Peroxisome proliferator-activated receptor-α expression induces alterations in cardiac myofilaments in a pressure-overload model of hypertrophy.

Although alterations in fatty acid (FA) metabolism have been shown to have a negative impact on contractility of the hypertrophied heart, the targets of action remain elusive. In this study we compared the function of skinned fiber bundles from transgenic (Tg) mice that overexpress a relatively low level of the peroxisome proliferator-activated receptor α (PPARα), and nontransgenic (NTg) littermates. The mice (NTg-T and Tg-T) were stressed by transverse aortic constriction (TAC) and compared with shams (NTg-S and Tg-S). There was an approximate 4-fold increase in PPARα expression in Tg-S compared with NTg-S, but Tg-T hearts showed the same PPARα expression as NTg-T. Expression of PPARα did not alter the hypertrophic response to TAC but did reduce ejection fraction (EF) in Tg-T hearts compared with other groups. The rate of actomyosin ATP hydrolysis was significantly higher in Tg-S skinned fiber bundles compared with all other groups. Tg-T hearts showed an increase in phosphorylation of specific sites on cardiac myosin binding protein-C (cMyBP-C) and ß-myosin heavy chain isoform. These results advance our understanding of potential signaling to the myofilaments induced by altered FA metabolism under normal and pathological states. We demonstrate that chronic and transient PPARα activation during pathological stress alters myofilament response to Ca2+ through a mechanism that is possibly mediated by MyBP-C phosphorylation and myosin heavy chain isoforms.NEW & NOTEWORTHY Data presented here demonstrate novel signaling to sarcomeric proteins by chronic alterations in fatty acid metabolism induced by PPARα. The mechanism involves modifications of key myofilament regulatory proteins modifying cross-bridge dynamics with differential effects in controls and hearts stressed by pressure overload.

Green Tea Catechin Normalizes the Enhanced Ca2+ Sensitivity of Myofilaments Regulated by a Hypertrophic Cardiomyopathy-Associated Mutation in Human Cardiac Troponin I (K206I).

BACKGROUND: Hypertrophic cardiomyopathy (HCM) is the most common inherited cardiovascular disease characterized by thickening of ventricular walls and decreased left ventricular chamber volume. The majority of HCM-associated mutations are found in genes encoding sarcomere proteins. Herein, we set out to functionally characterize a novel HCM-associated mutation (K206I-TNNI3) and elucidate the mechanism of dysfunction at the level of myofilament proteins. METHODS AND RESULTS: The male index case was diagnosed with HCM after an out-of-hospital cardiac arrest, which was followed by comprehensive clinical evaluation, transthoracic echocardiography, and clinical genetic testing. To determine molecular mechanism(s) of the mutant human cardiac troponin I (K206I), we tested the Ca(2+) dependence of thin filament-activated myosin-S1-ATPase activity in a reconstituted, regulated, actomyosin system comparing wild-type human troponin complex, 50% mix of K206I/wildtype, or 100% K206I. We also exchanged native troponin detergent extracted fibers with reconstituted troponin containing either wildtype or a 65% mix of K206I/wildtype and measured force generation. The Ca(2+) sensitivity of the myofilaments containing the K206I variant was significantly increased, and when treated with 20 µmol/L (-)-epigallocatechin gallate (green tea) was restored back to wild-type levels in ATPase and force measurements. The K206I mutation impairs the ability of the troponin I to inhibit ATPase activity in the absence of calcium-bound human cardiac troponin C. The ability of calcium-bound human cardiac troponin C to neutralize the inhibition of K206I was greater than with wild-type TnI. CONCLUSIONS: Compromised interactions of K206I with actin and hcTnC may lead to impaired relaxation and HCM.

Expression of tropomyosin-κ induces dilated cardiomyopathy and depresses cardiac myofilament tension by mechanisms involving cross-bridge dependent activation and altered tropomyosin phosphorylation.

Tropomyosin-kappa (TPM1-κ) is a newly discovered tropomyosin (TM) isoform that is exclusively expressed in the human heart and generated by an alternative splicing of the α-TM gene. We reported that TPM1-κ expression was increased in the hearts of patients with chronic dilated cardiomyopathy (DCM). To increase our understanding of the significance of this shift in isoform population, we generated transgenic (TG) mice expressing TPM1-κ in the cardiac compartment where TPM1-κ replaces 90% of the native TM. We previously showed that there was a significant inhibition of the ability of strongly bound cross-bridges to induce activation of TG myofilaments (Rajan et al., Circulation 121:410-418, 2010). Here, we compared the force-Ca(2+) relations in detergent extracted (skinned) fiber bundles isolated from non-transgenic (NTG) and TG-TPM1-κ hearts at two sarcomere lengths (SLs). Our data demonstrated a significant decrease in the Ca(2+) sensitivity of the myofilaments from TG-TPM1-κ hearts with no change in the maximum developed tension, length-dependent activation, and the ratio of ATPase rate to tension. There was also no difference in the affinity and cooperativity of Ca(2+)-binding to troponin in thin filaments reconstituted with either TPM1-κ or α-TM. We also compared protein phosphorylation in NTG and TG-TPM1-κ myofilaments. There was a decrease in the total phosphorylation of TPM1-κ compared to α-TM, but no significant change in other major sarcomeric proteins. Our results identify a novel mode of myofilament desensitization to Ca(2+) associated with a DCM linked switch in TM isoform population.

Molecular and functional characterization of a novel cardiac-specific human tropomyosin isoform.

BACKGROUND: Tropomyosin (TM), an essential actin-binding protein, is central to the control of calcium-regulated striated muscle contraction. Although TPM1alpha (also called alpha-TM) is the predominant TM isoform in human hearts, the precise TM isoform composition remains unclear. METHODS AND RESULTS: In this study, we quantified for the first time the levels of striated muscle TM isoforms in human heart, including a novel isoform called TPM1kappa. By developing a TPM1kappa-specific antibody, we found that the TPM1kappa protein is expressed and incorporated into organized myofibrils in hearts and that its level is increased in human dilated cardiomyopathy and heart failure. To investigate the role of TPM1kappa in sarcomeric function, we generated transgenic mice overexpressing cardiac-specific TPM1kappa. Incorporation of increased levels of TPM1kappa protein in myofilaments leads to dilated cardiomyopathy. Physiological alterations include decreased fractional shortening, systolic and diastolic dysfunction, and decreased myofilament calcium sensitivity with no change in maximum developed tension. Additional biophysical studies demonstrate less structural stability and weaker actin-binding affinity of TPM1kappa compared with TPM1alpha. CONCLUSIONS: This functional analysis of TPM1kappa provides a possible mechanism for the consequences of the TM isoform switch observed in dilated cardiomyopathy and heart failure patients.

Effect of type-1 diabetes mellitus on the regulation of insulin and endothelin-1 receptors in rat hearts.

This project assesses the treatment role with insulin and (or) angiotensin II receptor subtype-1 (AT1-R) blocker (ARB) on insulin receptor and endothelin-1 receptor subtype (ETA-R and ETB-R) regulation in rat hearts suffering from insulin-dependent diabetes mellitus (IDDM). Animals were divided into 6 groups: groups 1, 3, and 5 were controls consisting of normal, diabetic (streptozotocin-treated, once at 0 time), and diabetic supplemented daily with insulin, respectively, whereas groups 2, 4, and 6 were the controls treated daily with losartan. One month after enrollment, rats were sacrificed and samples of cardiac tissue were snapped frozen for immunostaining and Western blotting. Insulin receptor density was observed to be upregulated in the cardiomyocytes of diabetic animals, but downregulated with insulin supplementation alone. Cotreatment with insulin and an ARB resulted in drastic increase in insulin-receptor density in the diabetic rats. In addition, expression of ETA-R in cardiomyocytes was upregulated and was consistently maintained within the various treatment modalities. However, ETB-R expression was significantly reduced in the diabetic group treated with both insulin and an ARB. The changes in the expression of the insulin, the ETA-Rs, and the ETB-Rs at the various sites of the myocardium and the effect of both insulin treatment and blockade of the AT1-R explain the new benefits related to the halting of myocardial remodeling in IDDM rats.

Effect of insulin and angiotensin II receptor subtype-1 antagonist on myocardial remodelling in rats with insulin-dependent diabetes mellitus.

OBJECTIVES: To assess the role of insulin or an angiotensin II receptor antagonist (losartan), or both, in preventing cardiomyocyte damage in rats suffering from insulin-dependent diabetes mellitus (IDDM), and to correlate it with insulin receptor modulation at the cardiomyocyte, coronary endothelium and skeletal muscle cell level. DESIGN: Animals were divided into groups of normal rats, diabetic rats, and diabetic rats given insulin, each subdivided into a control group and an experimental group treated with losartan. METHODS: The animals were killed 1 month after enrollment to the study. Perfusion of the heart with iodine-125-labelled insulin was carried out for all the groups and the binding kinetics of insulin to its receptors on the coronary endothelial cells and the cardiomyocytes were determined using a physical/mathematical model. In addition, tissue samples from the heart and intercostal skeletal muscle were snap frozen and used for histological, indirect immunofluorescence and western blot analysis. RESULTS: Cardiac muscle from diabetic animals exhibited diffuse cardiomyopathic changes consisting of widespread vacuolation, loss of striation and cellular hypertrophy, which were reduced and even prevented by treatment with insulin and losartan. In addition, losartan seemed to mediate the upregulation of insulin receptor density on cardiomyocytes and skeletal muscle, and increase insulin receptor affinity at the coronary endothelial site. Finally, treatment with losartan induced a significant decrease in glucose concentrations in the diabetic group compared with the appropriate controls. CONCLUSIONS: Addition of losartan to the standard insulin treatment in non-hypertensive animals with IDDM offers new benefits concerning cardiac protection and prevention of damage. This may be attributed, in part, to insulin receptor density and sensitization.

Effect of systemic insulin and angiotensin II receptor subtype-1 antagonist on endothelin-1 receptor subtype(s) regulation and binding in diabetic rat heart.

This study reports on the regulation and remodeling role of endothelin-1 (ET-1) and its receptor subtypes, ET(A)-Rs/ET(B)-Rs, at the coronary endothelium (CE) and cardiomyocyte (CM) sites. It is carried out in normal and normotensive rats with streptozotocin-induced diabetes mellitus receiving different treatment modalities. Normal rats were divided into two groups, namely a placebo (N) and a losartan-treated (NL), and diabetic rats into four groups receiving placebo (D), insulin-treated (DI), losartan-treated (DL), and insulin/losartan-treated (DIL) respectively. Binding kinetics of ET-1 to ET(A)-Rs/ET(B)-Rs on CE and CMs were assessed in the above groups to try to explain the effect of therapeutic doses of an angiotensin II receptor subtype-1 blocker on the dynamics of this ligand and its receptor in insulin supplemented diabetic animals. Each group was divided into two subgroups: CHAPS-untreated and CHAPS-treated rat hearts perfused with [125I]ET-1 to respectively estimate ET-1 binding affinity (tau = 1/k-n) to its receptor subtype(s) on CE and CMs using mathematical modeling describing a 1:1 reversible binding stoichiometry. Heart perfusion results revealed that insulin treatment significantly decreased tau on CE but not on CMs in diabetic rats. In diabetics treated with losartan, an increase in tau value on CE but not on CMs was noted. Cotreatment of diabetic rats with insulin and losartan normalized tau on CE but decreased it on CMs. Western blot, using snap-frozen heart tissues, revealed increase in ET(A)-R density in all diabetic groups. However, significant decrease in ET(B)-R density was observed in all groups compared to the normal, and was reconfirmed by immunohistochemical analysis. In conclusion, coadministration of insulin and losartan in nonhypertensive animals suffering from diabetes type 1 may offer new cardiac protection benefits by improving coronary blood flow and cardiomyocyte contractility through modulating ET-1 receptor subtypes density and affinity at CE and CM sites.

Intraocular pressure change measured by Goldmann tonometry after laser in situ keratomileusis.

PURPOSE: To assess the accuracy of Goldmann tonometry after laser in situ keratomileusis (LASIK). SETTING: University-based refractive surgery group (Clinique du Laser Visuel). METHOD: The database of patients who had LASIK was retrospectively reviewed. Preoperative and postoperative intraocular pressure (IOP) was measured in 145 patients. The correlation between decrease in IOP and various preoperative and intraoperative parameters was evaluated by regression analysis. Only one eye in patients having bilateral surgery was used for statistical analysis. RESULTS: Laser in situ keratomileusis was associated with a mean decrease in IOP of 1.9 mm Hg +/- 2.9 (SD). There was no significant correlation between the decrease and any parameter evaluated. CONCLUSION: Intraocular pressure after LASIK decreased by a mean of 1.9 +/- 2.9 mm Hg. The cause of the decrease remains unknown.

Urethral lengthening and reimplantation: incidence and management of catheterization problems.

PURPOSE: Creation of a 1-way catheterizable valve has resulted in dryness for a large group of children with intractable urinary incontinence. We document the incidence, time course and management of catheterization problems in 49 children who underwent urethral lengthening and reimplantation for intractable incontinence. MATERIALS AND METHODS: We reviewed the records of 21 boys and 28 girls who underwent urethral lengthening and reimplantation between 1982 and 1995. Catheterization problems were defined as the inability of the patient or a family member to pass the catheter, and divided into early only, late only, recurrent and persistent problems. RESULTS: Of the 49 patients 46 had neurogenic incontinence secondary to myelomeningocele and 35 (72%) never had difficulty catheterizing. Of the 14 children (28%) who had difficulty 7 (50%) were boys and 7 (50%) were girls. Two children (4%) with early only difficult catheterization have had no further difficulties during the last 14 and 6 years, respectively. In 3 children (6%) late only difficult catheterization began 17, 24 and 35 months, respectively, after the original bladder neck surgery. These problems were solved by changing to a Coudé catheter and/or avoiding over distension. The 7 patients (14%) with recurrent catheterization problems, some with long intervals between episodes, now catheterize easily. The 2 children (4%) with persistent problems required alternate access to the bladder. CONCLUSIONS: The majority of children (72%) who undergo urethral lengthening and reimplantation never have any difficulty catheterizing. Those in whom difficult catheterization develops can be treated with minimally invasive methods without compromising the goals of the original surgery.

A V1-vascular vasopressin antagonist suitable for radioiodination and photoaffinity labeling.

We have previously characterized the V1-vascular arginine vasopressin (AVP) receptors of human platelets (Thibonnier M, J Biol Chem 1987;262: 10960-10964). We now report on a radiomonoiodinated and photoreactive V1-vascular AVP antagonist (V1-ag) to be used for the purification of human V1-vascular AVP receptors. The V1-ag, d(CH2)5Tyr(Me)Tyr(NH2)AVP was modified by radiomonoiodination of d(CH2)5-Tyr(Me)Tyr(NH2)AVP with the Iodogen technique, and derivatization of d(CH2)5Tyr(Me)Tyr[125I](NH2)-AVP with the photoreactive crosslinker, N-hydroxysuccinimidyl-4-azidobenzoate (HSAB) (each step included HPLC purification). In competition experiments, the affinity of these V1-ag for the human platelet AVP receptors remained excellent: [table: see text] Irreversible photoaffinity labeling of the platelet V1-vascular AVP receptor was successfully achieved by UV lamp exposure (365 nm, 20 min). Thus, AzBz-d(CH2)5Tyr(Me)Tyr[125I](NH2)AVP is a promising tool to use for the purification of human V1-vascular AVP receptors.

Recording of brain potentials with FET-circuits: hazard of inadvertent lesions.

Head-mounted field-effect transistors are frequently used for electrophysiological recording of brain potentials in freely moving animals. The low output impedance of these transistors reduces noise pickup and artifacts caused by movement of the cable that connects the animal to the amplifier. However, inadvertent brain lesions can occur if the positive pole of the DC power supply is disconnected, without simultaneous interruption of the connections to the negative pole and ground.

Mycobacterium chelonei keratitis following penetrating keratoplasty.

Atypical mycobacteria are responsible for an increasing number of skin and soft-tissue infections. We present a case of Mycobacterium chelonei keratitis that developed 3 months after penetrating keratoplasty. Our case illustrates how early diagnosis of M. chelonei keratitis and aggressive therapy with appropriate antibiotics can lead to a complete cure, with excellent functional results.