Predicting bone loss following orthotopic liver transplantation

BACKGROUND: Hepatic osteodystrophy occurs in the majority of patients with advanced chronic liver disease with the abnormalities in bone metabolism accelerating following orthotopic liver transplantation (OLT). AIMS: To examine changes in bone mineral density (BMD) following OLT and to investigate factors that lead to bone loss. METHODS: Twelve patients had BMD (at both the lumbar spine (LS) and femoral neck (FN)) and biochemical markers measured preoperatively and for 24 months following OLT. RESULTS: BMD was low in 75% of patients prior to OLT and decreased significantly from baseline at the LS at three months and the FN at six months. BMD began to increase thereafter at both sites, approaching baseline values at the LS by 12 months. Bone formation markers, osteocalcin and procollagen type I carboxy propeptide, decreased immediately post-OLT, with a concomitant increase seen in the resorption markers pyridinoline and deoxypyridinoline. This resulted in a negative uncoupling index early post-OLT, that rebounded to positive values after six months. There was a significant correlation between the change in the uncoupling index between six and three months which preceded the increase in BMD at 12 months. The decrease in BMD recorded early post-OLT correlated with vitamin D levels at three months. CONCLUSIONS: Results suggest that increased resorption and inadequate formation are the major contributors to additional bone loss following OLT. Non-invasive biochemical markers precede later changes in BMD in this patient group following OLT and may have a role in investigating and planning intervention strategies to prevent bone loss in future studies.     

Remodeling of myocyte gap junctions in arrhythmogenic right ventricular cardiomyopathy due to a deletion in plakoglobin (Naxos disease).

OBJECTIVES: We tested the hypothesis that defective interactions between adhesion junctions and the cytoskeleton caused by the plakoglobin mutation in Naxos disease lead to remodeling of gap junctions and altered expression of the major gap junction protein, connexin43. BACKGROUND: Naxos disease, a recessive form of arrhythmogenic right ventricular cardiomyopathy, is associated with a high incidence of arrhythmias and sudden cardiac death. Naxos disease is caused by a mutation in plakoglobin, a protein that links cell-cell adhesion molecules to the cytoskeleton. METHODS: Myocardial expression of connexin43 and other intercellular junction proteins was characterized in 4 patients with Naxos disease. Immunohistochemistry was performed in all 4 patients, and immunoblotting and electron microscopy were performed in 1 patient who died in childhood before overt arrhythmogenic right ventricular cardiomyopathy had developed. RESULTS: Connexin43 expression at intercellular junctions was reduced significantly in both right and left ventricles in all patients with Naxos disease. Electron microscopy revealed smaller and fewer gap junctions interconnecting ventricular myocytes. Mutant plakoglobin was expressed but failed to localize normally at intercellular junctions. Localization of N-cadherin, alpha- and beta-catenins, plakophilin-2, desmoplakin-1, and desmocollin-2 at intercalated disks appeared normal. CONCLUSIONS: Remodeling of gap junctions occurs early in Naxos disease, presumably because of abnormal linkage between mechanical junctions and the cytoskeleton. Gap junction remodeling may produce a coupling defect which, combined with the subsequent development of pathologic changes in myocardium, could contribute to a highly arrhythmogenic substrate and enhance the risk of sudden death in Naxos disease.     

Macrolides: A Canadian Infectious Disease Society position paper

Since the introduction of erythromycin in 1965, no new compounds from the macrolide antimicrobial class were licensed in Canada until the 1990s. Clarithromycin and azithromycin, since their introduction, have become important agents for treating a number of common and uncommon infectious diseases. They have become prime agents in the treatment of respiratory tract infections, and have revolutionized the management of both genital chlamydial infections, by the use of single-dose therapy with azithromycin, and nontuberculous mycobacterial infections, by the use of clarithromycin. The improvement of clarithromycin and azithromycin over the gastrointestinal intolerability of erythromycin has led to supplanting the use of the latter for many primary care physicians. Unfortunately, the use of these agents has also increased the likelihood for misuse and has raised concerns about a resultant increase in the rates of macrolide resistance in many important pathogens, such as Streptococcus pneumoniae. This paper reviews the pharmacology and evidence for the current indications for use of these newer agents, and provides recommendations for appropriate use.Key Words: Azithromycin, Clarithromycin, Erythromycin, Macrolides, Review, Therapeutic useErythromycin A is a naturally occurring, microbiologically active compound of the macrolide class of antibiotics. Chemical modification of erythromycin A''s 14-membered lactone ring has led to the formation of semisynthetic derivatives with not only improved bioavailability and tolerability, but also expanded spectrums of microbiological activity and improved pharmacokinetic profiles. Such modifications produced clarithromycin, classified as a macrolide because it retains the central 14-membered lactone ring (1,2), and azithromycin, classified as an azalide due to its 15-membered aglycone ring (1). The latter two compounds are the newest agents in the macrolide class licensed for use in Canada. Roxithromycin and dirithromycin are available in other countries.These compounds are clinically active against Gram-positive and Gram-negative cocci, and Gram-negative bacilli (primarily Haemophilus influenzae, Legionella species, Moraxella catarrhalis, Campylobacter jejuni, Bordatella pertussis and Helicobacter pylori). Azalides such as azithromycin have exhibited superior activity against Gram-negative pathogens and are generally less active against Gram-positive pathogens. Intracellular pathogens such as Chlamydia species, Mycoplasma species, Ureaplasma species, Borrelia species and nontuberculous mycobacteria species show varying susceptibilities. On the basis of their microbial activity, both the macrolides and azalides have been shown to be clinically useful in the treatment of uncomplicated skin and soft tissue infections, upper and lower respiratory tract infections, sexually transmitted Chlamydia trachomatis infection and peptic ulcer disease. Additionally, the improved pharmacokinetic profiles and acid stability exhibited by the newer agents may lead to enhanced patient adherence through less frequent dosing and improved bioavailability in the presence of food.     

Value Driven Outcomes (VDO): a pragmatic,modular, and extensible software framework for understanding and improving health care costs and outcomes

Objective To develop expeditiously a pragmatic, modular, and extensible software framework for understanding and improving healthcare value (costs relative to outcomes).Materials and methods In 2012, a multidisciplinary team was assembled by the leadership of the University of Utah Health Sciences Center and charged with rapidly developing a pragmatic and actionable analytics framework for understanding and enhancing healthcare value. Based on an analysis of relevant prior work, a value analytics framework known as Value Driven Outcomes (VDO) was developed using an agile methodology. Evaluation consisted of measurement against project objectives, including implementation timeliness, system performance, completeness, accuracy, extensibility, adoption, satisfaction, and the ability to support value improvement.Results A modular, extensible framework was developed to allocate clinical care costs to individual patient encounters. For example, labor costs in a hospital unit are allocated to patients based on the hours they spent in the unit; actual medication acquisition costs are allocated to patients based on utilization; and radiology costs are allocated based on the minutes required for study performance. Relevant process and outcome measures are also available. A visualization layer facilitates the identification of value improvement opportunities, such as high-volume, high-cost case types with high variability in costs across providers. Initial implementation was completed within 6 months, and all project objectives were fulfilled. The framework has been improved iteratively and is now a foundational tool for delivering high-value care.Conclusions The framework described can be expeditiously implemented to provide a pragmatic, modular, and extensible approach to understanding and improving healthcare value.     

Artificial intelligence in gastroenterology: A state-of-the-art review

The development of artificial intelligence (AI) has increased dramatically in the last 20 years, with clinical applications progressively being explored for most of the medical specialties. The field of gastroenterology and hepatology, substantially reliant on vast amounts of imaging studies, is not an exception. The clinical applications of AI systems in this field include the identification of premalignant or malignant lesions (e.g., identification of dysplasia or esophageal adenocarcinoma in Barrett’s esophagus, pancreatic malignancies), detection of lesions (e.g., polyp identification and classification, small-bowel bleeding lesion on capsule endoscopy, pancreatic cystic lesions), development of objective scoring systems for risk stratification, predicting disease prognosis or treatment response [e.g., determining survival in patients post-resection of hepatocellular carcinoma), determining which patients with inflammatory bowel disease (IBD) will benefit from biologic therapy], or evaluation of metrics such as bowel preparation score or quality of endoscopic examination. The objective of this comprehensive review is to analyze the available AI-related studies pertaining to the entirety of the gastrointestinal tract, including the upper, middle and lower tracts; IBD; the hepatobiliary system; and the pancreas, discussing the findings and clinical applications, as well as outlining the current limitations and future directions in this field.     

Fractal correlation properties of R-R interval dynamics in asymptomatic relatives of patients with dilated cardiomyopathy

BACKGROUND AND AIM: asymptomatic relatives of patients with familial dilated cardiomyopathy who have left ventricular enlargement [LVE] are at risk for progression to dilated cardiomyopathy. A novel index of the fractal correlation properties of heart rate variability (HRV), the short-term scaling component (proportional, variant(1)) in detrended fluctuation analysis, is a promising prognostic tool in left ventricular dysfunction. The aim of this study was to compare values of proportional, variant(1) and conventional HRV indices in LVE relatives with dilated cardiomyopathy patients and normal controls. METHODS: time-domain and spectral HRV measures, and the short-term scaling component ( proportional, variant(1)) were assessed from 24-h Holter recordings from 22 LVE relatives (left ventricular end-diastolic dimension >112% predicted, normal fractional shortening), 24 dilated cardiomyopathy patients and 14 controls. RESULTS: the time domain index SDNN was lower in dilated cardiomyopathy patients [101.8(+/-44.0)] than in LVE relatives [161.7(+/-53.9)] or controls [152.9(+/-51.4)], P=0.01. Similarly, triangular index and spectral measures were reduced in dilated cardiomyopathy patients but not in LVE relatives or controls. In contrast, the short term scaling component ( proportional, variant(1)) in detrended fluctuation analysis was reduced in both dilated cardiomyopathy patients [1.06(+/-0.33)] and in LVE relatives [1.15 (+/-0.20)], compared with controls [1.32(+/-0.16)], P=0.01. Among DCM patients the short-term scaling component ( proportional, variant(1)) was significantly associated with echocardiographic deterioration during follow-up (3.7+/-2.1 year) (P=0.004). CONCLUSION: the short-term scaling component ( proportional, variant(1)) is reduced in asymptomatic relatives of dilated cardiomyopathy patients who have LVE.     

Ventricular tachycardia of left bundle branch block configuration in patients with isolated right ventricular dilatation. Clinical and electrophysiological features

Electrophysiological studies showed ventricular tachycardia in five patients (four male, one female) with isolated right ventricular dilatation. All had been asymptomatic before the onset of palpitation which had developed in adolescence or early adult life. Tachycardia had been associated with syncope in four patients, and three had been resuscitated from ventricular fibrillation before investigation. The electrocardiogram during ventricular tachycardia showed a left bundle branch block pattern, and endocardial mapping at electrophysiological study confirmed the right ventricular origin. The presenting tachycardia could be induced in all patients by programmed stimulation, and in three patients ventricular tachycardia of differing configuration could be induced, but the right ventricular origin and left bundle branch block pattern were maintained. In two patients ventricular tachycardia degenerated into ventricular fibrillation. Cineangiography, cross sectional echocardiography, and multigated radionuclide angiography confirmed the dilated abnormal right ventricle while indicating that left ventricular function was normal. On resting electrocardiograms T wave inversion over the right precordial leads was the sole abnormality. There were no signs of right heart failure and exercise tolerance was normal. Four patients have received maintenance treatment with antiarrhythmic drugs, and one had undergone operative mapping and ablative surgery. Thus ventricular tachycardia complicating right ventricular dilatation may be associated with serious symptoms and ventricular electrical instability; and in adults it may be suspected on clinical grounds by inverted T waves in the right precordial leads.     

Comparison of clinical, morphological, and prognostic features in hypertrophic cardiomyopathy between Japanese and western patients

Apical hypertrophic cardiomyopathy appears to be more common in Japan than in the West. Explanations for this difference include variable methods and criteria for the diagnosis. To assess morphological, clinical, and prognostic differences, 45 consecutive Japanese and 45 age- and gender-matched Western patients with hypertrophic cardiomyopathy were evaluated in two referral institutions by the same individuals. The diagnosis of hypertrophic cardiomyopathy was based on the echocardiographic demonstration of unexplained left ventricular hypertrophy. Patients were aged 8 to 64 years (mean 50); there were 66 males and 24 females. The pattern of left ventricular hypertrophy was similar in Japanese and Western patients: asymmetric septal 64 vs. 76%, concentric 22 vs. 13%, and apical 13 vs. 11% (p = NS). The incidence of an echocardiographic or Doppler calculated left ventricular gradient of > 30 mmHg was similar (11 vs. 18%; p = NS). The maximal left ventricular wall thickness was greater in Western patients (23 +/- 7 vs. 20 +/- 4 mm; p = 0.03), but was not different when adjusted for body surface area. Clinical features including incidence of family history and ventricular tachycardia during 24-h ambulatory electrocardiography were similar. During follow-up (4.9 +/- 4.0 years for Western vs. 4.4 +/- 2.0 years for Japanese), disease-related mortality was worse in Western patients (p < 0.05; 10 versus 2 patients). This evaluation, using the same diagnostic methods and criteria, reveals a worse prognosis in Western patients despite a similar clinical and morphological spectrum of hypertrophic cardiomyopathy.