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The UV absorption spectrum of all-trans-octatetraene is reinvestigated theoretically, focussing on the strongly dipole-allowed 1 A g – 1 B u transition. The dynamical calculations rely on ab initio multistate CASPT2 (MS-CASPT2) computations of the underlying potential energy surfaces and coupling elements, and the multiconfiguration time-dependent Hartree (MCTDH) method for solving the time-dependent Schrödinger equation for the nuclear motion. The vibronic structure of the absorption band near 2700 Å is well reproduced, better than ever before by a purely ab initio approach. The C–C single bond and C = C double bond stretching modes dominate the vibrational structure of the transition. While the latter resembles nearly harmonic motion on weakly coupled potential energy surfaces, the time-dependent calculations reveal a subpicosecond electronic population transfer from the 1 B u state to the lower-lying 2 A g state proceeding on a time scale of ∼ 50 fs . The details of this internal conversion process and its relation to the conical intersection between the two excited states are discussed, paying particular attention to the impact of the 1 B u – 2 A g energy gap on the dynamics. [ABSTRACT FROM AUTHOR]

Uremic malnutrition and chronic inflammation are important comorbid conditions that predict poor clinical outcome in end-stage renal disease (ESRD) patients. These conditions are also closely associated with cardiovascular disease, the major cause of death in ESRD patients. A pathophysiologic link between malnutrition, inflammation, and atherosclerosis has been proposed in this patient population. Indeed, multiple lines of evidence suggest that chronic inflammation can predispose ESRD patients to a catabolic and atherogenic state. Malnutrition can also result from chronic inflammation and can accelerate the progression of cardiovascular disease. Whereas a single common etiology has not been identified in this complex process, nutritional and anti-inflammatory interventions provide potential treatment options to counter the high mortality and morbidity in ESRD patients. Key Words: end-stage renal disease, uremic malnutrition, chronic inflammation, atherosclerosis

Hemodialysis stimulates muscle and whole body protein loss and alters substrate oxidation. Am J Physiol Endocrinol Metab 282: E107-E116, 2002.--The hemodialysis (HD) procedure has been implicated as a potential catabolic factor predisposing the chronic HD (CHD) patients to protein calorie malnutrition. To assess the potential effects of HD on protein and energy metabolism, we studied 11 CHD patients 2 h before, during, and 2 h after HD by use of primed constant infusion of L-[1-[sup.13]C]leucine and L-[ring-[sup.2][H.sub.5]]phenylalanine. Our results showed that HD led to increased whole body (10%) and muscle protein (133%) proteolysis. Simultaneously, whole body protein synthesis did not change, and forearm synthesis increased (120%). The net result was increased net whole body protein loss (96%) and net forearm protein loss (164%). During the 2-h post-HD period, the muscle protein breakdown trended toward baseline, whereas whole body protein breakdown increased further. Substrate oxidation during the post-HD was significantly altered, with diminished carbohydrate and accelerated lipid and amino acid oxidation. These data demonstrate that hemodialysis is an overall catabolic event, decreasing the circulating amino acids, accelerating rates of whole body and muscle proteolysis, stimulating muscle release of amino acids, and elevating net whole body and muscle protein loss. catabolism; malnutrition; inflammation; energy expenditure; metabolism

A synthetic membrane used in dialysis treatments may be more effective than the standard cuprophane membrane in improving kidney function. A study of 72 patients with acute kidney failure undergoing hemodialysis to cleanse their blood found the synthetic polymethyl methacrylate membrane to be associated with a higher survival rate than the cuprophane membrane (80% versus 40%). The synthetic membrane may be more compatible with the body than the cuprophane membrane. This may enable patients with acute kidney failure to recover kidney function, and enable long-term dialysis patients to retain some kidney function for a longer period of time. The synthetic membrane may not activate the body's white blood cells as does the cuprophane membrane. This could may make a difference in the success of dialysis for patients with oliguria (reduced urine output). The synthetic membrane may cost more than the cuprophane membrane, but the improved treatment rate may more than pay for the difference.

Purpose: Mortality among first-year hemodialysis (HD) patients remains unacceptably high. To address this problem, we estimate the proportions of early HD deaths that are potentially preventable by modifying known risk factors. Methods: We included 15,891 HD patients (within 60 days of starting HD) from 21 countries in the Dialysis Outcomes and Practice Patterns Study (1996– 2015), a prospective cohort study. Using Cox regression adjusted for potential confounders, we estimated the fraction of first-year deaths attributable to one or more of twelve modifiable risk factors (the population attributable fraction, AF) identified from the published literature by comparing predicted survival based on risk factors observed vs counterfactually set to reference levels. Results: The highest AFs were for catheter use (22%), albumin < 3.5 g/dL (19%), and creatinine < 6 mg/dL (12%). AFs were 5%-9% for no pre-HD nephrology care, no residual urine volume, systolic blood pressure < 130 or ≥ 160 mm Hg, phosphorus < 3.5 or ≥ 5.5 mg/dL, hemoglobin < 10 or ≥ 12 g/dL, and white blood cell count > 10,000/μL. AFs for ferritin, calcium, and PTH were < 3%. Overall, 65% (95% CI: 59%-71%) of deaths were attributable to these 12 risk factors. Additionally, the AF for C-reactive protein > 10 mg/L was 21% in facilities where it was routinely measured. Conclusion: A substantial proportion of first-year HD deaths could be prevented by successfully modifying a few risk factors. Highest priorities should be decreasing catheter use and limiting malnutrition/inflammation whenever possible. [ABSTRACT FROM AUTHOR]