Dimensionless index of the mitral valve for evaluation of degenerative mitral stenosis.

PURPOSE: Degenerative mitral stenosis (DMS) is an increasingly recognized cause of mitral stenosis. The goal of this study was to compare echocardiographic differences between DMS and rheumatic mitral stenosis (RMS), identify echocardiographic variables reflective of DMS severity, and propose a dimensionless mitral stenosis index (DMSI) for assessment of DMS severity. METHODS: This is a single-center, retrospective cohort study. We included patients with at least mild MS and a mean transmitral pressure gradient (TMPG) ≥4 mm Hg. Mitral valve area by the continuity equation (MVACEQ ) was used as an independent reference. The DMSI was calculated as follows: DMSI = VTILVOT / VTIMV. All-cause mortality data were collected retrospectively. RESULTS: A total of 64 patients with DMS and 24 patients with RMS were identified. MVACEQ was larger in patients with DMS (1.43 ± 0.4 cm2 ) than RMS (0.9 ± 0.3 cm2 ) by ~0.5 cm2 (P = <.001), and mean TMPG was lower in the DMS group (6.0 ± 2 vs 7.9 ± 3 mm Hg, P = .003). A DMSI of ≤0.50 and ≤0.351 was associated with MVACEQ ≤1.5 and MVACEQ ≤1.0 cm2 (P < .001), respectively. With the progression of DMS from severe to very severe, there was a significant drop in DMSI. There was a nonsignificant trend toward worse survival in patients with MVACEQ ≤1.0 cm2 and DMSI ≤0.35, suggesting severe stenosis severity. CONCLUSION: Our results show that TMPG correlates poorly with MVA in patients with DMS. Proposed DMSI may serve as a simple echocardiographic indicator of hemodynamically significant DMS.

Adherence to Discounting Guidelines: Evidence from Over 2000 Published Cost-Effectiveness Analyses.

Previous studies have shown that not all cost-effectiveness analyses (CEAs) adhere to recommended guidelines on intertemporal discounting. This analysis investigates adherence in a sample of over 2000 CEAs from seven countries. Guideline discount rates were retrieved for Australia, Belgium, Canada, Ireland, The Netherlands, New Zealand and the UK. Data on the rates applied in published CEAs were retrieved from the Tufts CEA Registry from the sample countries within the periods covered by the discounting guidelines. The relationship between adherence and candidate explanatory factors were assessed using logistic regression. The analysis appraised 2270 CEAs. The overall rate of adherence to discounting recommendations was 79%. Country-specific adherence ranged from 28% in New Zealand to 87% in Belgium and the UK. Adherence in Australia and Canada was 73% and 66%, respectively. Adherence is statistically significantly higher in more recent studies, countries currently applying differential discounting and manufacturer-sponsored studies. Relative to the reference case of Australia, adherence is statistically significantly higher in the UK and lower in Canada and New Zealand. There is notable variation in the rates of adherence to discounting recommendations between countries and over time. Incomplete adherence raises concerns regarding the comparability of evidence between studies. In turn, this raises concerns regarding equity of access to scarce healthcare resources. Journal editors should ensure that adherence to discounting recommendations is assessed as part of the peer review process.

Prognostic Implications of Left Ventricular Hypertrophy.

Left ventricular hypertrophy (LVH) was one of the earliest studied echocardiographic characteristics of the left ventricle. As the myriad of measurable metrics has multiplied over recent years, this reliable and relevant variable can often be overlooked. In this paper, we discuss appropriate techniques for accurate analysis, underlying pathophysiology, and the contributions from various risk factors. The prognostic implications of LVH on stroke, serious arrhythmias, and sudden cardiac death are reviewed. Finally, we examine the effect of therapy to reduce LVH and the resultant clinical outcomes.

Echocardiographic Assessment of Degenerative Mitral Stenosis: A Diagnostic Challenge of an Emerging Cardiac Disease.

Degenerative mitral stenosis (DMS) is characterized by decreased mitral valve (MV) orifice area and increased transmitral pressure gradient due to chronic noninflammatory degeneration and subsequent calcification of the fibrous mitral annulus and the MV leaflets. The "true" prevalence of DMS in the general population is unknown. DMS predominantly affects elderly individuals, many of whom have multiple other comorbidities. Transcatheter MV replacement techniques, although their long-term outcomes are yet to be tested, have been gaining popularity and may emerge as more effective and relatively safer treatment option for patients with DMS. Echocardiography is the primary imaging modality for evaluation of DMS and related hemodynamic abnormalities such as increased transmitral pressure gradient and pulmonary arterial pressure. Classic echocardiographic techniques used for evaluation of mitral stenosis (pressure half time, proximal isovelocity surface area, continuity equation, and MV area planimetry) lack validation for DMS. Direct planimetry with 3-dimensional echocardiography and color flow Doppler is a reasonable technique for determining MV area in DMS. Cardiac computed tomography is an essential tool for planning potential interventions or surgeries for DMS. This article reviews the current concepts on mitral annular calcification and its role in DMS. We then discuss the epidemiology, natural history, differential diagnosis, mechanisms, and echocardiographic assessment of DMS.

Current Perspectives on Left Ventricular Geometry in Systemic Hypertension.

Hypertension (HTN) is a global health problem and a leading risk factor for cardiovascular disease (CVD) morbidity and mortality. The hemodynamic overload from HTN causes left ventricular (LV) remodeling, which usually manifests as distinct alterations in LV geometry, such as concentric remodeling or concentric and eccentric LV hypertrophy (LVH). In addition to being a common target organ response to HTN, LV geometric abnormalities are well-known independent risk factors for CVD. Because of their prognostic implications and quantifiable nature, changes in LV geometric parameters have commonly been included as an outcome in anti-HTN drug trials. The purpose of this paper is to review the relationship between HTN and LV geometric changes with a focus on (1) diagnostic approach, (2) epidemiology, (3) pathophysiology, (4) prognostic effect and (5) LV response to anti-HTN therapy and its impact on CVD risk reduction.

Development and Implementation of a Quality Improvement Process for Echocardiographic Laboratory Accreditation.

We describe our process for quality improvement (QI) for a 3-year accreditation cycle in echocardiography by the Intersocietal Accreditation Commission (IAC) for a large group practice. Echocardiographic laboratory accreditation by the IAC was introduced in 1996, which is not required but could impact reimbursement. To ensure high-quality patient care and community recognition as a facility committed to providing high-quality echocardiographic services, we applied for IAC accreditation in 2010. Currently, there is little published data regarding the IAC process to meet echocardiography standards. We describe our approach for developing a multicampus QI process for echocardiographic laboratory accreditation during the 3-year cycle of accreditation by the IAC. We developed a quarterly review assessing (1) the variability of the interpretations, (2) the quality of the examinations, (3) a correlation of echocardiographic studies with other imaging modalities, (4) the timely completion of reports, (5) procedure volume, (6) maintenance of Continuing Medical Education credits by faculty, and (7) meeting Appropriate Use Criteria. We developed and implemented a multicampus process for QI during the 3-year accreditation cycle by the IAC for Echocardiography. We documented both the process and the achievement of those metrics by the Echocardiography Laboratories at the Ochsner Medical Institutions. We found the QI process using IAC standards to be a continuous educational experience for our Echocardiography Laboratory physicians and staff. We offer our process as an example and guide for other echocardiography laboratories who wish to apply for such accreditation or reaccreditation.

Implementation of a standardized pathway for the treatment of cardiac arrest patients using therapeutic hypothermia: "CODE ICE".

Out-of-hospital cardiac arrest is common and is associated with high mortality. The majority of in-hospital deaths from resuscitated victims of cardiac arrest are due to neurologic injury. Therapeutic hypothermia (TH) is now recommended for the management of comatose survivors of cardiac arrest. The rapid triage and standardized treatment of cardiac arrest patients can be challenging, and implementation of a TH program requires a multidisciplinary team approach. In 2010, we revised our institution's TH protocol, creating a "CODE ICE" pathway to improve the timely and coordinated care of cardiac arrest patients. As part of CODE ICE, we implemented comprehensive care pathways including measures such as a burst paging system and computerized physician support tools. "STEMI on ICE" integrates TH with our regional ST-elevation myocardial infarction network. Retrospective data were collected on 150 consecutive comatose cardiac arrest victims treated with TH (n = 82 pre-CODE ICE and n = 68 post-CODE ICE) from 2007 to 2011. After implementation of CODE ICE, the mean time to initiation of TH decreased from 306 ± 165 minutes to 196 ± 144 minutes (P < 0.001), and the time to target temperature decreased from 532 ± 214 minutes to 392 ± 215 minutes (P < 0.001). There was no significant change in survival or neurologic outcome at hospital discharge. Through the implementation of CODE ICE, we were able to reduce the time to initiation of TH and time to reach target temperature. Additional studies are needed to determine the effect of CODE ICE and similar pathways on clinical outcomes after cardiac arrest.

Evaluation of FiberLoop sutures in locking and nonlocking tendon repair.

UNLABELLED: The FiberLoop suture has been developed as a double stranded, double-armed suture of FiberWire, but has not been previously studied. This is a comparison study of FiberLoop, FiberWire, and Ethibond. METHODS: Six groups of bovine tendons were randomly sorted for testing. They were cut and repaired using FiberWire, FiberLoop, and Ethibond with modified Kessler and modified Krackow repair techniques. A 4-0 core suture was used and tested to failure. RESULTS: Both FiberLoop and FiberWire were significantly stronger than Ethibond regardless of the repair technique used. There was no difference between the nonlocking and locking repair technique in any of the suture groups. However, the nonlocking technique failed by tissue pull through while the locking technique failed by suture breakage. CONCLUSIONS: The FiberLoop suture and the FiberWire suture were significantly stronger than the Ethibond suture. Additionally, this study shows that the 4-0 suture is of adequate strength to repair a tendon injury. The double-armed Fiberloop may translate into quicker tendon repairs without sacrificing strength.

Interleukin-15 affects serotonin system and exerts antidepressive effects through IL15Rα receptor.

Contrary to the reduction of depressive-like behavior observed in several strains of cytokine receptor knockout mice, mice lacking the specific receptor for interleukin (IL)-15 showed increased immobility in tail suspension and modified forced swimming tests. There was also a reduction in social interactions. The hippocampus of the IL15Rα knockout mice had decreased mRNA for 5-HT(1A), increased mRNA for 5-HT(2C), and region-specific changes of serotonin reuptake transporter (SERT) immunoreactivity. Fluoxetine (the classic antidepressant Prozac, which inhibits 5-HT(2C) and SERT) reduced the immobility of the IL15Rα knockout mice in comparison with their pretreatment baseline. Together with the unchanged performance of the IL15Rα knockout mice on the rotarod, this response to fluoxetine indicates that the immobility reflects depression. Wildtype mice responded to IL15 treatment with improvement of immobility induced by forced swimming, whereas the knockout mice failed to respond. Thus, the cognate IL15 receptor is necessary for the antidepressive activity of IL15. In ex vivo studies, IL15 decreased synaptosomal uptake of 5-HT, and modulated the expression of 5-HT(2C) and SERT in cultured neurons in a dose- and time-dependent manner. Thus, the effect of IL15 on serotonin transmission may underlie the depressive-like behavior of IL15Rα knockout mice. We speculate that IL15 is essential to maintain neurochemical homeostasis and thereby plays a role in preventing neuropsychiatric symptoms.

Identification and functional characterization of a stable, centrally active derivative of the neurotensin (8-13) fragment as a potential first-in-class analgesic.

The neurotensin hexapapetide fragment NT(8-13) is a potent analgesic when administered directly to the central nervous system but does not cross the blood-brain barrier. A total of 43 novel derivatives of NT(8-13) were evaluated, with one, ABS212 (1), being most active in four rat models of pain when administered peripherally. Compound 1 binds to human neurotensin receptors 1 and 2 with IC(50) of 10.6 and 54.2 nM, respectively, and tolerance to the compound in a rat pain model did not develop after 12 days of daily administration. When it was administered peripherally, serum levels and neurotensin receptor binding potency of 1 peaked within 5 min and returned to baseline within 90-120 min; however, analgesic activity remained near maximum for >240 min. This could be due to its metabolism into an active fragment; however, all 4- and 5-mer hydrolysis products were inactive. This pharmacokinetic/pharmacodynamic dichotomy is discussed. Compound 1 is a candidate for development as a first-in-class analgesic.

Antegrade and retrograde endoscopy for treatment of esophageal stricture.

Total or near-total esophageal stricture results from multiple processes. Traditional treatment with wire cannulation followed by serial dilation is often contraindicated due to poor visualization and the risk of perforation. We seek to demonstrate that combined antegrade and retrograde endoscopy are useful for treatment of total or near-total esophageal strictures. The gastrostomy tube is removed and the tract dilated. A standard endoscope is passed retrograde to the stricture. An antegrade endoscope is advanced until transillumination across the stricture is visualized. A biopsy forceps or needle is used to traverse the stricture in an antegrade fashion. The tract is cannulated with a stiff wire that is then brought out through the gastrostomy site. The stricture is serially dilated. The gastrostomy tube is replaced, and a nasogastric tube is left across the stricture for 3 to 4 weeks. The endoscope is withdrawn and an 18 or 20 Fr gastrostomy tube is left in place. A total of three patients with total esophageal strictures were treated using combined antegrade and retrograde esophagoscopy. All three patients regained the ability to swallow secretions. Importantly, there were no instances of esophageal perforation. This technique has broader application, including combination with minilaparotomy for patients without retrograde access. Further research is needed to determine durability of stricture dilation.

Excited state tautomerization of azaindole.

Fluorescent tryptophan analogs, like azatryptophan, offer an advantage for exploring protein and peptide structure and dynamics. The chromophoric moieties, azaindole, of the azatryptophan analogs are investigated for their potential as fluorescent probes. The photophysical properties of 4-azaindole (4AI) and 5-azaindole (5AI) and their tautomers are characterized through computational and experimental methods. Both 4AI and 5AI undergo excited state tautomerization in the presence of 1 M NaOH. The protonated forms of 4AI and 5AI have a fluorescence emission of 415 and 410 nm, respectively, while the tautomers of 4AI and 5AI have a fluorescent emission of 480 and 450 nm, respectively. Gas phase computations (B3LYP/6-31+G**) show that the N1H azaindole tautomer is lower in energy in the ground state by as much as 12.5 kcal mol(-1), while the N(n)H azaindole tautomer is lower in energy in the excited state by as much as 18.1 kcal mol(-1). Solvent effects on the tautomer energy differences were computed using the isodensity polarized continuum model (IPCM). The polarity of the solvent helps to reduce the energy difference between the tautomers in the ground state by as much as 5.8 kcal mol(-1), but not enough to reverse the ground state tautomer preference.

Structural analysis of xyloglucans in the primary cell walls of plants in the subclass Asteridae.

The structures of xyloglucans from several plants in the subclass Asteridae were examined to determine how their structures vary in different taxonomic orders. Xyloglucans, solubilized from plant cell walls by a sequential (enzymatic and chemical) extraction procedure, were isolated, and their structures were characterized by NMR spectroscopy and mass spectrometry. All campanulids examined, including Lactuca sativa (lettuce, order Asterales), Tenacetum ptarmiciflorum (dusty miller, order Asterales), and Daucus carota (carrot, order Apiales), produce typical xyloglucans that have an XXXG-type branching pattern and contain alpha-d-Xylp-, beta-D-Galp-(1-->2)-alpha-D-Xylp-, and alpha-L-Fucp-(1-->2)-beta-D-Galp-(1-->2)-alpha-D-Xylp- side chains. However, the lamiids produce atypical xyloglucans. For example, previous analyses showed that Capsicum annum (pepper) and Lycopersicon esculentum (tomato), two species in the order Solanales, and Olea europaea (olive, order Lamiales) produce xyloglucans that contain arabinosyl and galactosyl residues, but lack fucosyl residues. The XXGG-type xyloglucans produced by Solanaceous species are less branched than the XXXG-type xyloglucan produced by Olea europaea. This study shows that Ipomoea pupurea (morning glory, order Solanales), Ocimum basilicum (basil, order Lamiales), and Plantago major (plantain, order Lamiales) all produce xyloglucans that lack fucosyl residues and have an unusual XXGGG-type branching pattern in which the basic repeating core contains five glucose subunits in the backbone. Furthermore, Neruim oleander (order Gentianales) produces an XXXG-type xyloglucan that contains arabinosyl, galactosyl, and fucosyl residues. The appearance of this intermediate xyloglucan structure in oleander has implications regarding the evolutionary development of xyloglucan structure and its role in primary plant cell walls.

NMR characterization of endogenously O-acetylated oligosaccharides isolated from tomato (Lycopersicon esculentum) xyloglucan.

Eight oligosaccharide subunits, generated by endoglucanase treatment of the plant polysaccharide xyloglucan isolated from the culture filtrate of suspension-cultured tomato (Lycopersicon esculentum) cells, were structurally characterized by NMR spectroscopy. These oligosaccharides, which contain up to three endogenous O-acetyl substituents, consist of a cellotetraose core with alpha-D-Xylp residues at O-6 of the two beta-D-Glcp residues at the non-reducing end of the core. Some of the alpha-D-Xylp residues themselves bear either an alpha-L-Arap or a beta-D-Galp residue at O-2. O-Acetyl substituents are located at O-6 of the unbranched (internal) beta-D-Glcp residue, O-6 of the terminal beta-D-Galp residue, and/or at O-5 of the terminal alpha-L-Arap residue. Structural assignments were facilitated by long-range scalar coupling interactions observed in the high-resolution gCOSY spectra of the oligosaccharides. The presence of five-bond scalar coupling constants in the gCOSY spectra provides a direct method of assigning O-acetylation sites, which may prove generally useful in the analysis of O-acylated glycans. Spectral assignment of these endogenously O-acetylated oligosaccharides makes it possible to deduce correlations between their structural features and the chemical shifts of diagnostic resonances in their NMR spectra.

The reaction of indole with the aminoacrylate intermediate of Salmonella typhimurium tryptophan synthase: observation of a primary kinetic isotope effect with 3-[(2)H]indole.

The bacterial tryptophan synthase alpha(2)beta(2) complex catalyzes the final reactions in the biosynthesis of L-tryptophan. Indole is produced at the active site of the alpha-subunit and is transferred through a 25-30 A tunnel to the beta-active site, where it reacts with an aminoacrylate intermediate. Lane and Kirschner proposed a two-step nucleophilic addition-tautomerization mechanism for the reaction of indole with the aminoacrylate intermediate, based on the absence of an observed kinetic isotope effect (KIE) when 3-[(2)H]indole reacts with the aminoacrylate intermediate. We have now observed a KIE of 1.4-2.0 in the reaction of 3-[(2)H]indole with the aminoacrylate intermediate in the presence of monovalent cations, but not when an alpha-subunit ligand, disodium alpha-glycerophosphate (Na(2)GP), is present. Rapid-scanning stopped flow kinetic studies were performed of the reaction of indole and 3-[(2)H]indole with tryptophan synthase preincubated with L-serine, following the decay of the aminoacrylate intermediate at 350 nm, the formation of the quinonoid intermediate at 476 nm, and the formation of the L-Trp external aldimine at 423 nm. The addition of Na(2)GP dramatically slows the rate of reaction of indole with the alpha-aminoacrylate intermediate. A primary KIE is not observed in the reaction of 3-[(2)H]indole with the aminoacrylate complex of tryptophan synthase in the presence of Na(2)GP, suggesting binding of indole with tryptophan synthase is rate limiting under these conditions. The reaction of 2-methylindole does not show a KIE, either in the presence of Na(+) or Na(2)GP. These results support the previously proposed mechanism for the beta-reaction of tryptophan synthase, but suggest that the rate limiting step in quinonoid intermediate formation from indole and the aminoacrylate intermediate is deprotonation.

Simultaneous pancreas-kidney transplantation utilizing a common arterial conduit: early experience and potential applications.

Simultaneous pancreas-kidney transplantation has gained acceptance as a therapeutic modality for patients with end-stage renal disease secondary to diabetes mellitus. In some instances, performing the procedure as conventionally described with renal revascularization from the left iliac vessels and pancreatic arterial inflow from the right iliac vessels may be difficult or undesirable. We describe our experience with an alternate operative technique utilizing a single arterial conduit to vascularize both organs. We believe that this technique may be of use in certain patients undergoing simultaneous pancreas-kidney transplantation.