Use of quality indicators to evaluate the care of patients with localized prostate carcinoma

BACKGROUND The goal of quality assurance in health care is to preserve and improve patient care. Recently, RAND developed a set of evidence-based candidate indicators for evaluating the quality of care for patients with localized prostate carcinoma; however, the feasibility and sensitivity of these indicators have not been tested in a clinical setting. The objectives of this study were to evaluate the feasibility of measuring these quality indicators and to determine their sensitivity to change in practice patterns over time. METHODS One hundred sixty-eight men who presented in either 1995 or in 2000 and were treated for localized prostate carcinoma were selected randomly from the University of Michigan tumor registry. A combination of electronic data base review and explicit chart review was used to assess the feasibility of measuring compliance for each indicator. For each indicator in which assessment was feasible, compliance with the RAND indicators was determined for patients in both years. Multivariate regression analysis was used to adjust for potential confounding effects of disease stage, tumor grade, prostate specific antigen (PSA) level, patient age, and therapy. RESULTS Based on review of available clinical data, measurement of compliance was feasible for 19 of 22 RAND candidate quality indicators (86%). For five indicators, significant differences in documentation (compliance) were detected between 1995 and 2000 ( P < 0.05). Treatment received and higher PSA levels were associated independently with documentation of compliance for several indicators ( P < 0.05). CONCLUSIONS Measurement of the majority of the RAND quality indicators for the treatment of patients with localized prostate carcinoma was feasible, and improvements in several indicators were observed between 1995 and 2000. Demonstration of such variation, even within a single institution, suggests that the indicators are sufficiently sensitive to detect differences in practice patterns. Cancer 2003;97:1428–35. © 2003 American Cancer Society. DOI 10.1002/cncr.11216Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34367/1/11216_ftp.pd

The intracellular dynamic of protein palmitoylation

S-palmitoylation describes the reversible attachment of fatty acids (predominantly palmitate) onto cysteine residues via a labile thioester bond. This posttranslational modification impacts protein functionality by regulating membrane interactions, intracellular sorting, stability, and membrane micropatterning. Several recent findings have provided a tantalizing insight into the regulation and spatiotemporal dynamics of protein palmitoylation. In mammalian cells, the Golgi has emerged as a possible super-reaction center for the palmitoylation of peripheral membrane proteins, whereas palmitoylation reactions on post-Golgi compartments contribute to the regulation of specific substrates. In addition to palmitoylating and depalmitoylating enzymes, intracellular palmitoylation dynamics may also be controlled through interplay with distinct posttranslational modifications, such as phosphorylation and nitrosylation

Palmitoylation of the SNAP25 Protein Family: SPECIFICITY AND REGULATION BY DHHC PALMITOYL TRANSFERASES*

SNAP25 plays an essential role in neuronal exocytosis pathways. SNAP25a and SNAP25b are alternatively spliced isoforms differing by only nine amino acids, three of which occur within the palmitoylated cysteine-rich domain. SNAP23 is 60% identical to SNAP25 and has a distinct cysteine-rich domain to both SNAP25a and SNAP25b. Despite the conspicuous differences within the palmitoylated domains of these secretory proteins, there is no information on their comparative interactions with palmitoyl transferases. We report that membrane association of all SNAP25/23 proteins is enhanced by Golgi-localized DHHC3, DHHC7, and DHHC17. In contrast, DHHC15 promoted a statistically significant increase in membrane association of only SNAP25b. To investigate the underlying cause of this differential specificity, we examined a SNAP23 point mutant (C79F) designed to mimic the cysteine-rich domain of SNAP25b. DHHC15 promoted a marked increase in membrane binding and palmitoylation of this SNAP23 mutant, demonstrating that the distinct cysteine-rich domains of SNAP25/23 contribute to differential interactions with DHHC15. The lack of activity of DHHC15 toward wild-type SNAP23 was not overcome by replacing its DHHC domain with that from DHHC3, suggesting that substrate specificity is not determined by the DHHC domain alone. Interestingly, DHHC2, which is closely related to DHHC15, associates with the plasma membrane in PC12 cells and can palmitoylate all SNAP25 isoforms. DHHC2 is, thus, a candidate enzyme to regulate SNAP25/23 palmitoylation dynamics at the plasma membrane. Finally, we demonstrate that overexpression of specific Golgi-localized DHHC proteins active against SNAP25/23 proteins perturbs the normal secretion of human growth hormone from PC12 cells

Rapid and selective detection of fatty acylated proteins using ω-alkynyl-fatty acids and click chemistry[S]

Progress in understanding the biology of protein fatty acylation has been impeded by the lack of rapid direct detection and identification methods. We first report that a synthetic ω-alkynyl-palmitate analog can be readily and specifically incorporated into GAPDH or mitochondrial 3-hydroxyl-3-methylglutaryl-CoA synthase in vitro and reacted with an azido-biotin probe or the fluorogenic probe 3-azido-7-hydroxycoumarin using click chemistry for rapid detection by Western blotting or flat bed fluorescence scanning. The acylated cysteine residues were confirmed by MS. Second, ω-alkynyl-palmitate is preferentially incorporated into transiently expressed H- or N-Ras proteins (but not nonpalmitoylated K-Ras), compared with ω-alkynyl-myristate or ω-alkynyl-stearate, via an alkali sensitive thioester bond. Third, ω-alkynyl-myristate is specifically incorporated into endogenous co- and posttranslationally myristoylated proteins. The competitive inhibitors 2-bromopalmitate and 2-hydroxymyristate prevented incorporation of ω-alkynyl-palmitate and ω-alkynyl-myristate into palmitoylated and myristoylated proteins, respectively. Labeling cells with ω-alkynyl-palmitate does not affect membrane association of N-Ras. Furthermore, the palmitoylation of endogenous proteins including H- and N-Ras could be easily detected using ω-alkynyl-palmitate as label in cultured HeLa, Jurkat, and COS-7 cells, and, promisingly, in mice. The ω-alkynyl-myristate and -palmitate analogs used with click chemistry and azido-probes will be invaluable to study protein acylation in vitro, in cells, and in vivo

Palmitoylation and Membrane Interactions of the Neuroprotective Chaperone Cysteine-string Protein*S⃞

Cysteine-string protein (CSP) is an extensively palmitoylated DnaJ-family chaperone, which exerts an important neuroprotective function. Palmitoylation is required for the intracellular sorting and function of CSP, and thus it is important to understand how this essential modification of CSP is regulated. Recent work identified 23 putative palmitoyl transferases containing a conserved DHHC domain in mammalian cells, and here we show that palmitoylation of CSP is enhanced specifically by co-expression of the Golgi-localized palmitoyl transferases DHHC3, DHHC7, DHHC15, or DHHC17. Indeed, these DHHC proteins promote stable membrane attachment of CSP, which is otherwise cytosolic. An inverse correlation was identified between membrane affinity of unpalmitoylated CSP mutants and subsequent palmitoylation: mutants with an increased membrane affinity localize to the endoplasmic reticulum (ER) and are physically separated from the Golgi-localized DHHC proteins. Palmitoylation of an ER-localized mutant could be rescued by brefeldin A treatment, which promotes the mixing of ER and Golgi membranes. Interestingly though, the palmitoylated mutant remained at the ER following brefeldin A washout and did not traffic to more distal membrane compartments. We propose that CSP has a weak membrane affinity that allows the protein to locate its partner Golgi-localized DHHC proteins directly by membrane “sampling.” Mutations that enhance membrane association prevent sampling and lead to accumulation of CSP on cellular membranes such as the ER. The coupling of CSP palmitoylation to Golgi membranes may thus be an important requirement for subsequent sorting