Meta-analysis of effect of vegetarian diet on ischemic heart disease and all-cause mortality.

OBJECTIVE: To summarize the association between vegetarian versus non-vegetarian diet on mortality due to ischemic heart disease, cerebrovascular disease, or all-cause mortality. METHODS: We searched PubMed, Cochrane databases, and ClinicalTrials.Gov from the inception of the databases to October 2019 with no language restriction. Randomized controlled trials or prospective observational studies comparing the association between vegetarian versus non-vegetarian diets among adults and reporting major adverse cardiovascular outcomes were selected. We used Paule-Mandel estimator for tau2 with Hartung-Knapp adjustment for random effects model to estimate risk ratio [RR] with 95% confidence interval [CI].The primary outcome of interest was all-cause mortality. The secondary outcome was ischemic heart disease mortality. RESULTS: Eight observational studies (n = 131,869) were included in the analysis. Over a weighted mean follow-up of 10.68 years, very low certainty of evidence concluded that a vegetarian diet compared with a non-vegetarian diet was associated with similar risk of all-cause (RR: 0.84, 95% CI: 0.65-1.07, I2 : 97%) or cerebrovascular mortality (RR: 0.84, 95% CI: 0.63-1.14, I2 : 90%), but was associated with a reduced risk of ischemic heart disease mortality (RR: 0.70, 95% CI: 0.55-0.89, I2 : 82%). CONCLUSION: A vegetarian diet, compared with a non-vegetarian diet, was associated with a reduced risk of ischemic heart disease mortality, whereas it had no effect on all-cause and cerebrovascular mortality. However, the results are to be considered with caution considering the low certainty of evidence. Despite recent studies supporting no restriction on animal protein intake gaining wide media attention and public traction, consideration for vegetarianism amongst those with risk factors for coronary artery disease should be contemplated.

The variability in neurological deficits in Duchenne muscular dystrophy patients may be explained by differences in dystrophin glycoprotein complexes in the brain and muscle.

Duchenne muscular dystrophy (DMD) is an X-linked recessive genetic neuromuscular disorder. The variability in neurologic deficits in DMD patients may be explained by the fact that (1) dystrophin containing complexes in the brain are more stable than dystrophin containing complexes in the muscle (2) neurons are not affected by the same stresses as muscle and (3) neurons have a greater capacity to buffer increases in intracellular calcium levels. In the muscle, the loss of dystrophin and subsequent loss of dystrophin-associated proteins (DAPs) affects the stability of the dystrophin-glycoprotein complex and calcium ion channels. It causes the sarcolemma of the muscle to tear and calcium ion leak. The subsequent calcium influx leads to calcium dependant proteolysis. In the brain, the structure of the dystrophin-containing complexes is completely different from the muscle. There are several dystrophin isoforms that combine with a completely different set of proteins compared to the muscle to form several different dystrophin-containing complexes. In addition, the loss of dystrophin does not affect the expression of DAPs. The heterogeneity of dystrophin-containing complexes and the continued expression of DAPs will result in more stable dystrophin-containing complexes in the DMD brain. Muscles are under more stress than neurons as they undergo contractions. This combined with txhe fact that the neurons have a better ability to buffer increases in calcium would suggest that neurons are less likely to be damaged despite the loss of dystrophin.

Renal epithelial cells retain primary cilia during human acute renal allograft rejection injury.

OBJECTIVES: Primary cilia are sensory organelles which co-ordinate several developmental/repair pathways including hedgehog signalling. Studies of human renal allografts suffering acute tubular necrosis have shown that length of primary cilia borne by epithelial cells doubles throughout the nephron and collecting duct, and then normalises as renal function returns. Conversely the loss of primary cilia has been reported in chronic allograft rejection and linked to defective hedgehog signalling. We investigated the fate of primary cilia in renal allografts suffering acute rejection. RESULTS: Here we observed that in renal allografts undergoing acute rejection, primary cilia were retained, with their length increasing 1 week after transplantation and remaining elevated. We used a mouse model of acute renal injury to demonstrate that elongated renal primary cilia in the injured renal tubule show evidence of smoothened accumulation, a biomarker for activation of hedgehog signalling. We conclude that primary cilium-mediated activation of hedgehog signalling is still possible during the acute phase of renal allograft rejection.

The Extent of Mechanical Esophageal Deviation to Avoid Esophageal Heating During Catheter Ablation of Atrial Fibrillation.

OBJECTIVES: This study sought to determine the extent of lateral esophageal displacement required during mechanical esophageal deviation (MED) and to eliminate luminal esophageal temperature elevation (LETElev) during pulmonary vein (PV) isolation. BACKGROUND: MED is a conceptually attractive strategy of minimizing esophageal injury while allowing uninterrupted energy delivery along the posterior left atrium during PV isolation. METHODS: MED was performed using a malleable metal stylet within a plastic tube placed within the esophagus. Barium was instilled to characterize the trailing esophageal edge. For each MED attempt, the MEDEffective, defined as the distance from the trailing esophageal edge-to-ablation line, was correlated to occurrences of LETElev. RESULTS: In 114 consecutive patients/221 PV pairs undergoing MED (age 62.1 ± 11 years, 75% men, 62%/38% paroxysmal/persistent AF), esophageal stretching invariably occurred such that the esophageal edge trailed behind the plastic tube. MEDEffective distances of 0 mm to 10 mm, 10 mm to 15 mm, 15 mm to 20 mm or >20 mm were achieved in 60 (27.1%), 64 (29%), 48 (21.7%), and 49 (22.2%) attempts, respectively. Overall, LET elevation >38°C occurred in 81 of 221 (36.7%) PV pairs. The incidence of LETElev among the 4 groups was 73.3%, 35.9%, 25%, and 4.1%, respectively. MEDEffective distances were 9.1 ± 6.5 mm and 18 ± 7.6 mm in patients with and without LETElev, respectively (p < 0.0001). Three patients (2.6%) experienced clinically significant MED-related trauma, albeit only with a stiffer stylet. CONCLUSIONS: Mechanical esophageal deviation >20 mm from the PV ablation line prevents significant esophageal heating during PV isolation, but this level of displacement was difficult to safely achieve with this off-the-shelf mechanical stylet approach.

Increased calcium in neurons in the cerebral cortex and cerebellum is not associated with cell loss in the mdx mouse model of Duchenne muscular dystrophy.

Duchenne muscular dystrophy (DMD) is a fatal neuromuscular disease resulting from mutation of the X-linked dystrophin gene. In addition to skeletal muscle pathology, cognitive deficits have been identified in patients with DMD. There is a lack of research investigating the pathological mechanisms underlying the neurological deficits apparent in DMD. The current study assessed whether increases in calcium contributed towards neuronal cell loss or histopathological changes in the genetically homologous mdx mouse model of DMD in sections from the cerebral cortex, hippocampus and cerebellum at 24 days, 12 weeks and 9 months of age. Alizarin S staining showed a significant increase in calcium-positive neurons in the mdx cerebral cortex at 24 days and 9 months and the cerebellum at 24 days, 12 weeks and 9 months compared with age-matched controls. However, neuronal cell counts of haemotoxylin and eosin-stained sections showed that altered calcium levels did not lead to neuronal cell loss. A better understanding of how the disruption of calcium regulation affects the function of neurons may explain the neurological deficits apparent in mdx mice and patients with DMD.

Visualizing renal primary cilia.

Renal primary cilia are microscopic sensory organelles found on the apical surface of epithelial cells of the nephron and collecting duct. They are based upon a microtubular cytoskeleton, bounded by a specialized membrane, and contain an array of proteins that facilitate their assembly, maintenance and function. Cilium-based signalling is important for the control of epithelial differentiation and has been implicated in the pathogenesis of various cystic kidney diseases and in renal repair. As such, visualizing renal primary cilia and understanding their composition has become an essential component of many studies of inherited kidney disease and mechanisms of epithelial regeneration. Primary cilia were initially identified in the kidney using electron microscopy and this remains a useful technique for the high resolution examination of these organelles. New reagents and techniques now also allow the structure and composition of primary cilia to be analysed in detail using fluorescence microscopy. Primary cilia can be imaged in situ in sections of kidney, and many renal-derived cell lines produce primary cilia in culture providing a simplified and accessible system in which to investigate these organelles. Here we outline microscopy-based techniques commonly used for studying renal primary cilia.

The fate of bone marrow-derived cells carrying a Polycystic Kidney Disease mutation in the genetically normal kidney.

BACKGROUND: Polycystic Kidney Disease (PKD) is a genetic condition in which dedifferentiated and highly proliferative epithelial cells form renal cysts and is frequently treated by renal transplantation. Studies have reported that bone marrow-derived cells give rise to renal epithelial cells, particularly following renal injury as often occurs during transplantation. This raises the possibility that bone marrow-derived cells from a PKD-afflicted recipient could populate a transplanted kidney and express a disease phenotype. However, for reasons that are not clear the reoccurrence of PKD has not been reported in a genetically normal renal graft. We used a mouse model to examine whether PKD mutant bone marrow-derived cells are capable of expressing a disease phenotype in the kidney. METHODS: Wild type female mice were transplanted with bone marrow from male mice homozygous for a PKD-causing mutation and subjected to renal injury. Y chromosome positive, bone marrow-derived cells in the kidney were assessed for epithelial markers. RESULTS: Mutant bone marrow-derived cells were present in the kidney. Some mutant cells were within the bounds of the tubule or duct, but none demonstrated convincing evidence of an epithelial phenotype. CONCLUSIONS: Bone marrow-derived cells appear incapable of giving rise to genuine epithelial cells and this is the most likely reason cysts do not reoccur in kidneys transplanted into PKD patients.

In vitro investigation of renal epithelial injury suggests that primary cilium length is regulated by hypoxia-inducible mechanisms.

Primary cilia are non-motile sensory organelles that project from cells in many tissues. The role of renal primary cilium-based signalling in regulating epithelial cell proliferation and differentiation is highlighted by studies showing that defects of the cilium lead to epithelial de-differentiation, over proliferation and polycystic kidney disease. Recent studies show that renal primary cilia may also play a role in controlling epithelial differentiation during renal repair. After injury, renal cilium length increases dramatically and then undergoes a normalization that coincides with structural and functional repair in both human patients and mouse models of renal injury. These changes in cilium length are likely to modulate cilium-based signalling, but the injury-related factors that influence renal primary cilium length have yet to be determined. Here, we investigated the effect of three factors commonly associated with renal injury on renal cilium length in an in vitro setting. MDCK (Madin Darby canine kidney) cell cultures bearing primary cilia were treated with BSA to simulate albuminuria, cobalt chloride to simulate hypoxia and the inflammation-related cytokine tumour necrosis factor α. Primary cilium length was only increased in cultures treated with cobalt chloride. Our results suggest a role for hypoxia and the induction of HIF-1α (hypoxia-inducible factor 1α) in increasing renal primary cilium length following renal injury.

Renal primary cilia lengthen after acute tubular necrosis.

Renal primary cilia are sensory antennas required for the maintenance of normal epithelial differentiation and proliferation in the kidney, but they also have a potential role in epithelial differentiation during renal injury and repair. In mice, tubular damage causes an increase in the length of renal cilia, which may modify their sensory sensitivity during repair. Here, we investigated whether the alteration of renal cilium length during renal injury is clinically relevant. Using biopsies of human renal transplants that suffered acute tubular necrosis during transplantation, we compared the length of renal primary cilia with renal function. Serial biopsies showed that acute tubular necrosis resulted in more than a doubling of cilium length throughout the nephron and collecting duct approximately 1 wk after injury. Allografts displayed a trend toward normalization of cilium length in later biopsies, and this correlated with functional recovery. A mouse model of renal ischemia-reperfusion confirmed the increase and subsequent regression of cilium length during renal repair, displaying complete normalization of cilium length within 6 wk of injury. These findings demonstrate that the length of renal cilia is a clinically relevant indicator of renal injury and repair.

Alterations in renal cilium length during transient complete ureteral obstruction in the mouse.

The renal cilium is a non-motile sensory organelle that has been implicated in the control of epithelial phenotype in the kidney. The contribution of renal cilium defects to cystic kidney disease has been the subject of intense study. However, very little is known of the behaviour of this organelle during renal injury and repair. Here we investigate the distribution and dimensions of renal cilia in a mouse model of unilateral ureteral obstruction and reversal of ureteral obstruction. An approximate doubling in the length of renal cilia was observed throughout the nephron and collecting duct of the kidney after 10 days of unilateral ureteral obstruction. A normalization of cilium length was observed during the resolution of renal injury that occurs following the release of ureteral obstruction. Thus variations in the length of the renal cilium appear to be a previously unappreciated indicator of the status of renal injury and repair. Furthermore, increased cilium length following renal injury has implications for the specification of epithelial phenotype during repair of the renal tubule and duct.

Renal cilia display length alterations following tubular injury and are present early in epithelial repair.

BACKGROUND: Renal cilia are flow sensors that are required for the maintenance of normal kidney architecture. Defects in this organelle are frequently associated with polycystic kidney disease, but the role of renal cilia during acute tubular injury has not been investigated. METHODS: We have analysed the presence and dimensions of renal cilia following renal ischaemia-reperfusion and ureteral obstruction injury in the mouse, and related these results to injury and repair of the renal tubule. The expression of genes encoding cilium-localized proteins was measured following ischaemia-reperfusion injury. RESULTS: Ischaemia-reperfusion injury was demonstrated to affect the length of cilia in the renal tubule and duct. The average length of renal cilia in the proximal tubule decreases 1 day (2.8 +/- 0.4 microm) and 2 days (3.0 +/- 0.2 microm) after injury, as compared to the control uninjured proximal tubule (4.2 +/- 0.3 microm). Later in the injury and repair process at 4 and 7 days, the average length of cilia increases in both the proximal (7 days = 6.2 +/- 0.3 microm) and distal tubule/collecting duct (4 days = 4.4 +/- 0.3 microm; 7 days = 5.5 +/- 0.4 microm; control 2.5 +/- 0.1 microm). The expression level of genes encoding cilium-localized products did not correlate with the increase in cilium length following ischaemia-reperfusion injury. Ureteral obstruction for 8 days also caused lengthening (8 days UUO = 5.8 +/- 0.3 microm; control 2.5 +/- 0.1 microm) of renal cilia in the distal tubule/collecting duct. During the repair process that follows ischaemia-reperfusion injury, cilia were present on the dedifferentiated cells that proliferate and adopt an epithelial phenotype to facilitate the repair of the ischaemic renal tubule. CONCLUSIONS: We propose roles for the renal cilium in responding to changes in the renal environment caused by injury, and in the repair process that re-establishes the epithelial layer of the damaged renal tubule.