8-Geranyloxypsoralen

2945163

A series of yeast mitochondrial mit- mutants with defects in the oli2 gene, coding for subunit 6 of the mitochondrial ATPase complex, has been analyzed at the DNA sequence level. Fifteen of sixteen primary mit- mutants were shown to contain frameshift or nonsense mutations predicting truncated subunit 6 polypeptides, in various strains ranging from about 20% to 95% of the wild-type length of 259 amino acids. In only one strain could the defect in subunit 6 function be assigned to amino acid substitution in an otherwise full-length subunit 6. Many mutants carried multiple base substitutions or insertions/deletions, presumably arising from the manganese chloride mutagenesis treatment. Revertants from three of the mit- mutants were analyzed: all contained full-length subunit 6 proteins with one or more amino acid substitutions. The preponderance of truncated proteins as opposed to substituted full-length proteins in oli2 mit- mutants is suggested to reflect the ability of subunit 6 to accommodate amino acid substitutions at many locations, with little or no change in its functional properties in the membrane FO-sector of the ATPase complex.

Biogenesis of mitochondria: DNA sequence analysis of mit- mutations in the mitochondrial oli2 gene coding for mitochondrial ATPase subunit 6 in Saccharomyces cerevisiae.

U P John, T A Willson, A W Linnane, and P Nagley

1986 Sep 25

28774932

Background Clinical outcomes after surgical treatment of mitral regurgitation (MR) are worse if intervention occurs after deterioration of left ventricular (LV) size and function. Trans-thoracic echocardiographic (TTE) surveillance of patients with MR is indicated to avoid adverse ventricular remodeling. Overly frequent TTEs can impair patient access and reduce value in care delivery. This balance between timely surveillance and over-utilization of TTE in valvular disease provides a model to study variation in the delivery of health care services. We investigated patient and provider factors contributing to variation in TTE utilization, and hypothesized that variation was attributable to provider practice even after adjustment for patient characteristics. Methods and Results We obtained records of all TTEs from 2001-2016 ordered at a large echocardiography laboratory. The outcome variable was time interval between TTEs. We constructed a mixed-effects linear regression model with the individual physician as the random effect in the model, and used intra-class correlation coefficient (ICC) to assess the proportion of outcome variation due to provider practice. Our study cohort was 55,773 TTEs corresponding to 37,843 intervals ordered by 635 providers. The mean interval between TTEs was 12.4 months, 17.0 months, 18.3 months, and 17.4 months for severe, moderate, mild, and trace MR respectively, with 20% of providers deemed over-utilizers of TTEs, and 25% under-utilizers. Conclusions We conclude that there is substantial variation in follow-up intervals for TTE assessment of MR, despite risk-adjustment for patient variables, likely due to provider factors.

Mitral Regurgitation, Quality of Care and Outcomes, Variation, Echocardiography

Variation in the echocardiographic surveillance of primary mitral regurgitation

Varsha K. Tanguturi, MD,1,3 Michael K. Hidrue, PhD,2 Michael H. Picard, MD,1,2,3 Steven J. Atlas, MD, MPH,2,3 Jeffrey B. Weilburg, MD,2 Timothy G. Ferris, MD, MPH,2 Katrina Armstrong, MD, MPH,3 and Jason H. Wasfy, MD, MPhil1,2

2018 Aug 1.