A study of lower hybrid wave propagation on the Versator II tokamak using microwave scattering

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 1986.Bibliography: leaves 114-115.by Rajeev Rajan Rohatgi.Ph.D

Effects of biomechanical forces on signaling in the cortical collecting duct (CCD)

An increase in tubular fluid flow rate (TFF) stimulates Na reabsorption and K secretion in the cortical collecting duct (CCD) and subjects cells therein to biomechanical forces including fluid shear stress (FSS) and circumferential stretch (CS). Intracellular MAPK and extracellular autocrine/paracrine PGE2 signaling regulate cation transport in the CCD and, at least in other systems, are affected by biomechanical forces. We hypothesized that FSS and CS differentially affect MAPK signaling and PGE2 release to modulate cation transport in the CCD. To validate that CS is a physiological force in vivo, we applied the intravital microscopic approach to rodent kidneys in vivo to show that saline or furosemide injection led to a 46.5 ± 2.0 or 170 ± 32% increase, respectively, in distal tubular diameter. Next, murine CCD (mpkCCD) cells were grown on glass or silicone coated with collagen type IV and subjected to 0 or 0.4 dyne/cm2 of FSS or 10% CS, respectively, forces chosen based on prior biomechanical modeling of ex vivo microperfused CCDs. Cells exposed to FSS expressed an approximately twofold greater abundance of phospho(p)-ERK and p-p38 vs. static cells, while CS did not alter p-p38 and p-ERK expression compared with unstretched controls. FSS induced whereas CS reduced PGE2 release by ∼40%. In conclusion, FSS and CS differentially affect ERK and p38 activation and PGE2 release in a cell culture model of the CD. We speculate that TFF differentially regulates biomechanical signaling and, in turn, cation transport in the CCD

The Golgin GMAP210/TRIP11 Anchors IFT20 to the Golgi Complex

Eukaryotic cells often use proteins localized to the ciliary membrane to monitor the extracellular environment. The mechanism by which proteins are sorted, specifically to this subdomain of the plasma membrane, is almost completely unknown. Previously, we showed that the IFT20 subunit of the intraflagellar transport particle is localized to the Golgi complex, in addition to the cilium and centrosome, and hypothesized that the Golgi pool of IFT20 plays a role in sorting proteins to the ciliary membrane. Here, we show that IFT20 is anchored to the Golgi complex by the golgin protein GMAP210/Trip11. Mice lacking GMAP210 die at birth with a pleiotropic phenotype that includes growth restriction, ventricular septal defects of the heart, omphalocele, and lung hypoplasia. Cells lacking GMAP210 have normal Golgi structure, but IFT20 is no longer localized to this organelle. GMAP210 is not absolutely required for ciliary assembly, but cilia on GMAP210 mutant cells are shorter than normal and have reduced amounts of the membrane protein polycystin-2 localized to them. This work suggests that GMAP210 and IFT20 function together at the Golgi in the sorting or transport of proteins destined for the ciliary membrane

Telenephrology: current perspectives and future?directions.

There is increasing interest in telemedicine among physicians and patients; however, the evidence regarding the quality of care delivered by telemedicine, and telenephrology in particular, compared with in-person care is limited. In this review, different electronic modalities used to deliver nephrology care are reviewed and critiqued, with a focused analysis from the Australian and United States perspectives. Both countries are geographically expansive with significant rural populations where access to nephrology care is limited. However, their health care systems are organized differently. The Australian health care system is a mostly nonprofit, single-payer system, whereas the United States system is more fractured with a greater proportion of patients covered by for-profit private insurance or no insurance coverage. Videoconferencing is widely used in Australia to manage kidney disease including chronic kidney disease, dialysis, pediatric nephrology, and post-kidney transplantation care. In contrast, the United States telenephrology experience is limited, with most reports originating from the Veterans Health Administration, a single-payer system providing care for nearly 9 million veterans, ?3 million of whom reside in rural communities. Preliminary reports from the Veterans Health Administration suggest that that delivery of nephrology care via videoconferencing results in clinical outcomes that are at least equivalent to in-person care and improved patient adherence to scheduled appointments. Nevertheless, large, adequately controlled studies are needed to identify patient populations that are most likely to benefit from telenephrology and to determine the optimal systems for the delivery of telenephrology care

Left ventricular outflow track obstruction and mitral valve regurgitation in a patient with takotsubo cardiomyopathy

Introduction: Takotsubo cardiomyopathy (TCM) can be complicated by left ventricular outflow tract (LVOT) obstruction and severe acute mitral regurgitation (MR), leading to hemodynamic instability in an otherwise benign disorder. Despite the severity of these complications, there is a paucity of literature on the matter. Because up to 20–25% of TCM patients develop LVOT obstruction and/or MR, it is important to recognize the clinical manifestations of these complications and to adhere to specific management in order to reduce patient morbidity and mortality. We report the clinical history, imaging, treatment strategy, and clinical outcome of a patient with TCM that was complicated with severe MR and LVOT obstruction. We then discuss the pathophysiology, characteristic imaging, key clinical features, and current treatment strategy for this unique patient population. Case report: A postmenopausal woman with no clear risk factor for coronary artery disease (CAD) presented to the emergency department with chest pain after an episode of mental/physical stress. Physical examination revealed MR, mild hypotension, and pulmonary vascular congestion. Her troponins were mildly elevated. Cardiac catheterization excluded obstructive CAD, but revealed severe apical hypokinesia and ballooning. Notably, multiple diagnostic tests revealed the presence of severe acute MR and LVOT obstruction. The patient was diagnosed with TCM complicated by underlying MR and LVOT obstruction, and mild hemodynamic instability. The mechanism of her LVOT and MR was attributed to systolic anterior motion of the mitral valve (SAM), which the transesophageal echocardiogram clearly showed during workup. She was treated with beta-blocker, aspirin, and ACE-I with good outcome. Nitroglycerin and inotropes were discontinued and further avoided. Conclusions: Our case illustrated LVOT obstruction and MR associated with underlying SAM in a patient with TCM. LVOT obstruction and MR are severe complications of TCM and may result in heart failure and/or pulmonary edema. Timely and accurate identification of these complications is critical to achieve optimal clinical outcomes in patients with TCM

Left ventricular outflow track obstruction and mitral valve regurgitation in a patient with takotsubo cardiomyopathy.

INTRODUCTION: Takotsubo cardiomyopathy (TCM) can be complicated by left ventricular outflow tract (LVOT) obstruction and severe acute mitral regurgitation (MR), leading to hemodynamic instability in an otherwise benign disorder. Despite the severity of these complications, there is a paucity of literature on the matter. Because up to 20-25% of TCM patients develop LVOT obstruction and/or MR, it is important to recognize the clinical manifestations of these complications and to adhere to specific management in order to reduce patient morbidity and mortality. We report the clinical history, imaging, treatment strategy, and clinical outcome of a patient with TCM that was complicated with severe MR and LVOT obstruction. We then discuss the pathophysiology, characteristic imaging, key clinical features, and current treatment strategy for this unique patient population. CASE REPORT: A postmenopausal woman with no clear risk factor for coronary artery disease (CAD) presented to the emergency department with chest pain after an episode of mental/physical stress. Physical examination revealed MR, mild hypotension, and pulmonary vascular congestion. Her troponins were mildly elevated. Cardiac catheterization excluded obstructive CAD, but revealed severe apical hypokinesia and ballooning. Notably, multiple diagnostic tests revealed the presence of severe acute MR and LVOT obstruction. The patient was diagnosed with TCM complicated by underlying MR and LVOT obstruction, and mild hemodynamic instability. The mechanism of her LVOT and MR was attributed to systolic anterior motion of the mitral valve (SAM), which the transesophageal echocardiogram clearly showed during workup. She was treated with beta-blocker, aspirin, and ACE-I with good outcome. Nitroglycerin and inotropes were discontinued and further avoided. CONCLUSIONS: Our case illustrated LVOT obstruction and MR associated with underlying SAM in a patient with TCM. LVOT obstruction and MR are severe complications of TCM and may result in heart failure and/or pulmonary edema. Timely and accurate identification of these complications is critical to achieve optimal clinical outcomes in patients with TCM