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3,459 result(s) for "Lee, Samuel S."
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β-blockers in advanced cirrhosis: More friend than enemy
Nonselective beta-adrenergic blocker (NSBB) therapy for the prevention of initial and recurrent gastrointestinal bleeding in cirrhotic patients with gastroesophageal varices has been used for the past four decades. NSBB therapy is considered the cornerstone of treatment for varices, and has become the standard of care. However, a 2010 study from the group that pioneered β-blocker therapy suggested a detrimental effect of NSBBs in decompensated cirrhosis, especially in patients with refractory ascites. Since then, numerous additional studies have incompletely resolved whether NSBBs are deleterious, although more recent evidence weighs against a harmful effect. The possibility of a “therapeutic window” has also been raised. We aimed to review the literature to analyze the pros and cons of using NSBBs in patients with cirrhosis, not only with respect to bleeding or mortality but also to other potential benefits and risks. β-blockers are highly effective in preventing first bleeding and recurrent bleeding. Furthermore, NSBBs improve congestion/ischemia of the gut mucosa, decrease intestinal permeability, and therefore indirectly alleviate systemic inflammation. β-blockers shorten the electrocardiographic prolonged QTc interval and may also decrease the incidence of hepatocellular carcinoma. On the other hand, the possibility of deleterious effects in cirrhosis has not been completely eliminated. NSBBs may be associated with an increased risk of portal vein thrombosis, although this could be correlational artifact. Overall, we conclude that β-blockers in cirrhosis are much more of a friend than enemy.
Role of Galectin in Cardiovascular Conditions including Cirrhotic Cardiomyopathy
Abnormal cardiac function in the setting of cirrhosis and in the absence of a primary cardiac disease is known as cirrhotic cardiomyopathy. The pathogenesis of cirrhotic cardiomyopathy is multifactorial but broadly is comprised of two pathways. The first is due to cirrhosis and synthetic liver failure with abnormal structure and function of many substances, including proteins, lipids, hormones, and carbohydrates such as lectins. The second is due to portal hypertension which invariably accompanies cirrhosis. Portal hypertension leads to a leaky, congested gut with resultant endotoxemia and systemic inflammation. This inflammatory phenotype comprises oxidative stress, cellular apoptosis, and inflammatory cell infiltration. Galectins exert all these pro-inflammatory mechanisms across many different tissues and organs, including the heart. Effective therapies for improving cardiac function in patients with cirrhosis are not available. Conventional strategies for other noncirrhotic heart diseases, including vasodilators, are not feasible because of the significant baseline vasodilation in cirrhotic patients. Therefore, exploring new treatment modalities for cirrhotic cardiomyopathy is of great importance. Galectin-3 inhibitors such as modified citrus pectin, N-acetyllactosamine, TD139 and GB0139 exert anti-apoptotic, anti-oxidative and anti-inflammatory effects and thus have potential therapeutic interest. This review briefly summarizes the physiological and pathophysiological role of galectin and specifically examines its role in cardiac disease processes. We present a more detailed discussion of galectin in cardiovascular complications of cirrhosis, particularly cirrhotic cardiomyopathy. Finally, therapeutic studies of galectin-3 inhibitors in cirrhotic cardiomyopathy are reviewed.
Oxidative stress triggers hyperdynamic circulation via central neural activation in portal hypertensive rats
Background Hyperdynamic circulation in portal hypertension (PHT) depends on central neural activation. However, the initiating mechanism that signals PHT to the central neural cardiovascular-regulatory centers remains unclear. We aimed to test the hypothesis that oxidative stress in the gut initiates the signal that activates central cardiovascular nuclei in portal hypertensive rats. Methods Two groups of rats were used. One had portal hypertension produced by partial portal vein ligation, while controls underwent sham operation. Hemodynamics including portal pressure, cardiac output, mean arterial pressure (MAP) and peripheral vascular resistance were measured. Activation of central cardiovascular nuclei was determined by immunohistochemical Fos expression in the paraventricular nucleus (PVN) of the hypothalamus. Myeloperoxidase activity, an oxidative stress marker, was measured in the jejunum. Hydrogen peroxide, the antioxidant N -acetyl-cysteine (NAC) or saline controls were administered for 12–14 days by gavage or osmotic minipumps placed in the peritoneal cavity. Results Compared with controls, PHT rats showed increased cardiac output (54.2 ± 9.5 vs 33.6 ± 2.4 ml/min/100 g BW, p  < 0.01), decreased MAP (96.2 ± 6.4 mmHg vs 103.2 ± 7.8, p  < 0.01) and systemic vascular resistance (1.84 ± 0.28 vs 3.14 ± 0.19 mmHg/min/ml/100 g BW, p  < 0.01). PHT rats had increased jejunal myeloperoxidase and PVN Fos expression. NAC treatment eliminated the hyperdynamic circulation, decreased jejunal myeloperoxidase and PVN Fos expression in PHT rats, but had no effect on sham controls. H 2 O 2 significantly increased PVN Fos expression and decreased MAP. Conclusion These results indicate that in PHT, mesenteric oxidative stress is the initial signal that activates chemoreceptors and triggers hyperdynamic circulation by central neural cardiovascular-regulatory centers.
Brain-Specific Rescue of Clock Reveals System-Driven Transcriptional Rhythms in Peripheral Tissue
The circadian regulatory network is organized in a hierarchical fashion, with a central oscillator in the suprachiasmatic nuclei (SCN) orchestrating circadian oscillations in peripheral tissues. The nature of the relationship between central and peripheral oscillators, however, is poorly understood. We used the tetOFF expression system to specifically restore Clock function in the brains of Clock(Δ19) mice, which have compromised circadian clocks. Rescued mice showed normal locomotor rhythms in constant darkness, with activity period lengths approximating wildtype controls. We used microarray analysis to assess whether brain-specific rescue of circadian rhythmicity was sufficient to restore circadian transcriptional output in the liver. Compared to Clock mutants, Clock-rescue mice showed significantly larger numbers of cycling transcripts with appropriate phase and period lengths, including many components of the core circadian oscillator. This indicates that the SCN oscillator overcomes local circadian defects and signals directly to the molecular clock. Interestingly, the vast majority of core clock genes in liver were responsive to Clock expression in the SCN, suggesting that core clock genes in peripheral tissues are intrinsically sensitive to SCN cues. Nevertheless, most circadian output in the liver was absent or severely low-amplitude in Clock-rescue animals, demonstrating that the majority of peripheral transcriptional rhythms depend on a fully functional local circadian oscillator. We identified several new system-driven rhythmic genes in the liver, including Alas1 and Mfsd2. Finally, we show that 12-hour transcriptional rhythms (i.e., circadian \"harmonics\") are disrupted by Clock loss-of-function. Brain-specific rescue of Clock converted 12-hour rhythms into 24-hour rhythms, suggesting that signaling via the central circadian oscillator is required to generate one of the two daily peaks of expression. Based on these data, we conclude that 12-hour rhythms are driven by interactions between central and peripheral circadian oscillators.
Galectin-3 inhibits cardiac contractility via a tumor necrosis factor alpha-dependent mechanism in cirrhotic rats
Background/Aims: Galectin-3 plays a key pathogenic role in cardiac hypertrophy and heart failure. The present study aimed to investigate the effects of galectin-3 on cardiomyopathy – related factors and cardiac contractility in a rat model of cirrhotic cardiomyopathy.Methods: Rats were divided into two sets, one for a functional study, the other for cardiac contractile-related protein evaluation. There were four groups in each set: sham operated and sham plus N-acetyllactosamine (N-Lac, a galectin-3 inhibitor; 5 mg/kg); bile duct ligated (BDL) and BDL plus N-Lac. Four weeks after surgery, ventricular level of galectin-3, collagen I and III ratio, tumor necrosis factor alpha (TNFα), and brain natriuretic peptide (BNP) were measured either by Western blots or immunohistochemistry or enzyme-linked immunosorbent assay. Blood pressure was measured by polygraph recorder. Cardiomyocyte contractility was measured by inverted microscopy.Results: Galectin-3 and collagen I/III ratio were significantly increased in cirrhotic hearts. TNFα and BNP were significantly increased in BDL serum and heart compared with sham controls. Galectin-3 inhibitor significantly decreased galectin-3, TNFα, and BNP in cirrhotic hearts but not in sham controls. N-Lac also significantly improved the blood pressure, and systolic and diastolic cardiomyocyte contractility in cirrhotic rats but had no effect on sham controls.Conclusion: Increased galectin-3 in the cirrhotic heart significantly inhibited contractility via TNFα. Inhibition of galectin-3 decreased the cardiac content of TNFα and BNP and reversed the decreased blood pressure and depressed contractility in the cirrhotic heart. Galectin-3 appears to play a pathogenic role in cirrhotic cardiomyopathy.
The Burden of Large and Small Duct Primary Sclerosing Cholangitis in Adults and Children: A Population-Based Analysis
The epidemiology of primary sclerosing cholangitis (PSC) has been incompletely assessed by population-based studies. We therefore conducted a population-based study to determine: (a) incidence rates of large and small duct PSC in adults and children, (b) the risk of inflammatory bowel disease on developing PSC, and (c) patterns of clinical presentation with the advent of magnetic resonance cholangiopancreatography (MRCP). All residents of the Calgary Health Region diagnosed with PSC between 2000 and 2005 were identified by medical records, endoscopic, diagnostic imaging, and pathology databases. Demographic and clinical information were obtained. Incidence rates were determined and risks associated with PSC were reported as rate ratios (RR) with 95% confidence intervals (CI). Forty-nine PSC patients were identified for an age- and gender-adjusted annual incidence rate of 0.92 cases per 100,000 person-years. The incidence of small duct PSC was 0.15/100,000. In children the incidence rate was 0.23/100,000 compared with 1.11/100,000 in adults. PSC risk was similar in Crohn's disease (CD; RR 220.0, 95% CI 132.4-343.7) and ulcerative colitis (UC; RR 212.4, 95% CI 116.1-356.5). Autoimmune hepatitis overlap was noted in 10% of cases. MRCP diagnosed large duct PSC in one-third of cases. Delay in diagnosis was common (median 8.4 months). A minority had complications at diagnosis: cholangitis (6.1%), pancreatitis (4.1%), and cirrhosis (4.1%). Pediatric cases and small duct PSC are less common than adult large duct PSC. Surprisingly, the risk of developing PSC in UC and CD was similar. Autoimmune hepatitis overlap was noted in a significant minority of cases.
Second-Line Treatment after Failure of Immune Checkpoint Inhibitors in Hepatocellular Carcinoma: Tyrosine Kinase Inhibitor, Retrial of Immunotherapy, or Locoregional Therapy?
Abstract Background: Immune checkpoint inhibitor (ICI)-based therapy such as atezolizumab plus bevacizumab or durvalumab plus tremelimumab became mainstream first-line systemic treatment in advanced hepatocellular carcinoma (HCC) patients since remarkably superior efficacy of ICI-based therapy compared to tyrosine kinase inhibitors (TKIs) was reported in two recent randomized controlled trials (RCTs) (IMbrave150, HIMALAYA). However, the optimal second-line therapy after treatment failure of first-line ICI-based therapy remains unknown as no RCT has examined this issue. Summary: Therefore, at present, most clinicians are empirically treating patients with TKIs or retrial of ICI or locoregional treatment (LRT) modality such as transarterial therapy, radiofrequency ablation, and radiation therapy in this clinical setting without solid evidence. In this review, we will discuss current optimal strategies for second-line treatment after the failure of first-line ICI-based therapy by reviewing published studies and ongoing prospective trials. Key Messages: Clinicians should consider carefully whether to treat the patients with TKI, other ICI-based therapy, or LRT in this situation by considering several factors including liver function reserve, performance status, adverse events of previous therapy, and presence of lesion that can consider LRT such as oligoprogression and vascular invasion. In the meantime, we await the results of ongoing prospective trials to elucidate the best management options.
Dysregulated Calcium Handling in Cirrhotic Cardiomyopathy
Cirrhotic cardiomyopathy is a syndrome of blunted cardiac systolic and diastolic function in patients with cirrhosis. However, the mechanisms remain incompletely known. Since contractility and relaxation depend on cardiomyocyte calcium transients, any factors that impact cardiac contractile and relaxation functions act eventually through calcium transients. In addition, calcium transients play an important role in cardiac arrhythmias. The present review summarizes the calcium handling system and its role in cardiac function in cirrhotic cardiomyopathy and its mechanisms. The calcium handling system includes calcium channels on the sarcolemmal plasma membrane of cardiomyocytes, the intracellular calcium-regulatory apparatus, and pertinent proteins in the cytosol. L-type calcium channels, the main calcium channel in the plasma membrane of cardiomyocytes, are decreased in the cirrhotic heart, and the calcium current is decreased during the action potential both at baseline and under stimulation of beta-adrenergic receptors, which reduces the signal to calcium-induced calcium release. The study of sarcomere length fluctuations and calcium transients demonstrated that calcium leakage exists in cirrhotic cardiomyocytes, which decreases the amount of calcium storage in the sarcoplasmic reticulum (SR). The decreased storage of calcium in the SR underlies the reduced calcium released from the SR, which results in decreased cardiac contractility. Based on studies of heart failure with non-cirrhotic cardiomyopathy, it is believed that the calcium leakage is due to the destabilization of interdomain interactions (dispersion) of ryanodine receptors (RyRs). A similar dispersion of RyRs may also play an important role in reduced contractility. Multiple defects in calcium handling thus contribute to the pathogenesis of cirrhotic cardiomyopathy.
Hepatitis C Diagnosis and Treatment Among Indigenous People in a Canadian Context: Challenges and Community-Led Solutions
The historical and ongoing impacts of the influence of colonization are experienced by Indigenous people in systemic racism, inequity in healthcare access, and intergenerational trauma; originating in the disruption of a way of life and seen in a grief response, with links to disparate hepatitis C virus (HCV) prevalence. Despite this, the focus often remains on the increased incidence without a strengths-based lens. Although HCV is a global concern that can result in cirrhosis, liver failure, or cancer, diagnosing and linking people to care and treatment early can prevent advanced liver disease. Efforts to engage certain priority populations are occurring; however, historical context and current practices are often forgotten or overlooked. This is especially true with respect to Indigenous people in Canada. This review considers the published literature to elucidate the context of historical and ongoing colonizing impacts seen in the current HCV treatment gaps experienced by Indigenous people in Canada. In addition, we highlight strengths-based and Indigenous-led initiatives and programming that inspire hopefulness and steps toward community-engaged solutions to meet the World Health Organization Goals of eliminating HCV as a public health threat.