Citations

AbstractAlthough useful palliation can often be achieved when external beam irradiation and chemotherapy are used to treat locally advanced gastrointestinal malignancies, local control and long‐term survival are infrequent in view of the limited tolerance of surrounding organs and tissues. In view of dose limitations of external beam irradiation, intraoperative irradiation (IORT) with electrons has been used as a supplement to external treatment in an attempt to improve the therapeutic ratio of local control versus complications. An IORT dose of 10 to 20 Gy has been combined with fractionated external beam doses of 45 to 55 Gy in 1.8 Gy fractions in studies performed in the United States, Japan, Europe, and Scandinavian countries. In this paper the indications for and the results of aggressive combined techniques that include IORT are discussed. Results obtained with external beam techniques alone or with chemotherapy and resection are presented by site to demonstrate the need for higher doses of irradiation. When results from IORT series are compared to standard treatment with regard to disease control and survival, local control appears better with locally advanced colorectal, gastric, and pancreatic cancer; and survival appears better with colorectal ± biliary cancers. With pancreatic cancer, improvements in local control do not translate into increased survival in view of the high incidence of subsequent liver and peritoneal failures. Implications for future strategies in all sites are discussed.

AbstractOur aim was to examine the long‐term success of cholecystoenterostomy performed for the relief of benign extrahepatic biliary obstruction. Concern about the ability of cholecystoenterostomy to provide reliable long‐term biliary decompression has led many to abandon its use for benign biliary obstruction. Thirty‐four patients who underwent cholecystoenterostomy for benign biliary obstruction over a 17‐year period were reviewed. Patients were followed until cholecystoenterostomy failure, death, or to date. Failure was defined as recurrent biliary obstruction or cholangitis requiring therapeutic intervention. Mean follow‐up was 8.0 years. Early postoperative morbidity occurred in 11 patients (32%), but only one early complication (cholangitis) was related directly to the cholecystoenteric anastomosis. Five patients (15%) experienced late biliary tract complications related directly to the cholecystoenterostomy including recurrent biliary stones with biliary obstruction in four and anastomotic stricture in one. All required reoperation and conversion to choledochoenterostomy at a mean of 112 months. Cholecystoenterostomy can provide reasonably effective long‐term biliary decompression in selected patients with benign biliary obstruction.

Background— Swimming is a relatively genotype-specific arrhythmogenic trigger for type 1 long-QT syndrome (LQT1). We hypothesize that mimickers of concealed LQT1, namely catecholaminergic polymorphic ventricular tachycardia (CPVT), may also underlie swimming-triggered cardiac events. Methods and Results— Between August 1997 and May 2003, 388 consecutive, unrelated patients were referred specifically for LQTS genetic testing. The presence of a personal and/or family history of a near-drowning or drowning was determined by review of the medical records and/or phone interviews and was blinded to genetic test results. Comprehensive mutational analysis of the 5 LQTS-causing channel genes, KCNQ1 (LQT1), KCNH2 (LQT2), SCN5A (LQT3), KCNE1 (LQT5), and KCNE2 (LQT6), along with KCNJ2 (Andersen-Tawil syndrome) and targeted analysis of 18 CPVT1-associated exons in RyR2 , was performed with the use of denaturing high-performance liquid chromatography and direct DNA sequencing. Approximately 11% (43 of 388) of the index cases had a positive swimming phenotype. Thirty-three of these 43 index cases had a “Schwartz” score (≥4) suggesting high clinical probability of LQTS. Among this subset, 28 patients (85%) were LQT1, 2 patients (6%) were LQT2, and 3 were genotype negative. Among the 10 cases with low clinical probability for LQTS, 9 had novel, putative CPVT1-causing RyR2 mutations. Conclusions— In contrast to previous studies that suggested universal LQT1 specificity, genetic heterogeneity underlies channelopathies that are suspected chiefly because of a near-drowning or drowning. CPVT1 and strategic genotyping of RyR2 should be considered when LQT1 is excluded in the pathogenesis of a swimming-triggered arrhythmia syndrome.

Transcutaneous partial pressure of oxygen (TcPO2) predicts wound healing in critical ischemia. However, no studies have controlled for the effect of wounds on TcPO2. In this study, in 24 hip or knee arthroplasty cases without vascular disease, TcPO2 was measured preoperatively at the incision site, contralaterally, and at a reference site on the chest wall. The measurements were repeated at 2 days and 2 months postoperatively and compared. TcPO2, normal preoperatively, decreased at all sites on the second postoperative day (p < 0.001), with a trend toward a greater decrease at the wound (p 1/4 0.09). All wounds healed, and TcPO2 returned to baseline at all sites 2 months postoperatively. In conclusion, acute surgical wounds are associated with a significant and widespread decrease in cutaneous TcPO2 in the setting of normal arterial perfusion. This decrease is likely multifactorial and deserves further investigation.

The mechanisms underlying CD4+ T cell depletion in human immunodeficiency virus (HIV) infection are not well understood. Comparative studies of lymphoid tissues, where the vast majority of T cells reside, and peripheral blood can potentially illuminate the pathogenesis of HIV-associated disease. Here, we studied the effect of HIV infection on the activation and depletion of defined subsets of CD4+ and CD8+ T cells in the blood, gastrointestinal (GI) tract, and lymph node (LN). We also measured HIV-specific T cell frequencies in LNs and blood, and LN collagen deposition to define architectural changes associated with chronic inflammation. The major findings to emerge are the following: the GI tract has the most substantial CD4+ T cell depletion at all stages of HIV disease; this depletion occurs preferentially within CCR5+ CD4+ T cells; HIV-associated immune activation results in abnormal accumulation of effector-type T cells within LNs; HIV-specific T cells in LNs do not account for all effector T cells; and T cell activation in LNs is associated with abnormal collagen deposition. Taken together, these findings define the nature and extent of CD4+ T cell depletion in lymphoid tissue and point to mechanisms of profound depletion of specific T cell subsets related to elimination of CCR5+ CD4+ T cell targets and disruption of T cell homeostasis that accompanies chronic immune activation.

Abstract Quantitative measurements of environmental factors greatly improve the quality of epidemiologic studies but can pose challenges because of the presence of upper or lower detection limits or interfering compounds, which do not allow for precise measured values. We consider the regression of an environmental measurement (dependent variable) on several covariates (independent variables). Various strategies are commonly employed to impute values for interval-measured data, including assignment of one-half the detection limit to nondetected values or of “fill-in” values randomly selected from an appropriate distribution. On the basis of a limited simulation study, we found that the former approach can be biased unless the percentage of measurements below detection limits is small (5–10%). The fill-in approach generally produces unbiased parameter estimates but may produce biased variance estimates and thereby distort inference when 30% or more of the data are below detection limits. Truncated data methods (e.g., Tobit regression) and multiple imputation offer two unbiased approaches for analyzing measurement data with detection limits. If interest resides solely on regression parameters, then Tobit regression can be used. If individualized values for measurements below detection limits are needed for additional analysis, such as relative risk regression or graphical display, then multiple imputation produces unbiased estimates and nominal confidence intervals unless the proportion of missing data is extreme. We illustrate various approaches using measurements of pesticide residues in carpet dust in control subjects from a case–control study of non-Hodgkin lymphoma.

AbstractAbnormalities of hemoglobin synthesis are usually inherited but may also arise as a secondary manifestation of another disease, most commonly hematologic neoplasia. Acquired hemoglobin disorders can be seen in any population and are not restricted to areas of the world with high incidences of inherited hemoglobinopathies. In fact, the acquired hemoglobinopathies may be more readily recognized where inherited hemoglobin abnormalities are rare and less likely to cause diagnostic confusion. Acquired α-thalassemia is the best characterized of the acquired red blood cell disorders in patients with hematologic malignancy, and it is almost always associated with a myelodysplastic syndrome (MDS). At least 2 molecular mechanisms for acquired α-thalassemia are now recognized: acquired deletion of the α-globin gene cluster limited to the neoplastic clone and, more commonly, inactivating somatic mutations of the trans-acting chromatin-associated factor ATRX, which cause dramatic down-regulation of α-globin gene expression. Here we review the clinical, hematologic, and molecular genetic features of α-thalassemia arising in a clonal myeloid disorder, and we discuss howATRX might affect gene expression in normal and abnormal hematopoiesis through epigenetic mechanisms.