Induction of chromosome aberrations and mitotic arrest by cytomegalovirus in human cells

Human cytomegalovirus (CMV) is potentially an effective but often overlooked genotoxic agent in humans. We report here evidence that indicates that infection by CMV can induce chromosome alterations and mitotic inhibition. The frequency of chromosome aberrations induced was dependent on the input multiplicity of infection (m.o.i.) for human lung fibroblasts (LU), but not for human peripheral blood lymphocytes (PBLs) when both cell types were infected at the GO phase of the cell cycle. The aberrations induced by CMV were mostly chromatid breaks and chromosome pulverizations that resembled prematurely condensed S-phase chromatin. Pulverized chromosomes were not observed in LU cells infected with virus stocks that had been rendered nonlytic by UV-irradiation at 24,000 ergs/mm2 or from infection of human lymphocytes. In LU cells infected with UV-irradiated CMV, the frequency of aberrations induced was inversely dependent on the extent of the exposure of the CMV stock to the UV-light. In permissive CMV infection of proliferating LU cells at 24 hr after subculture, a high percentage (greater than 40%) of the metaphase cells were arrested at their first metaphase and displayed severely condensed chromosomes when harvested 48 hr later. A significant increase (p less than 0.05) in the chromosome aberration frequency was also observed. Our study shows that CMV infection is genotoxic to host cells. The types and extent of damage are dependent on the viral genome expression and on the cell cycle stage of the cells at the time of infection. The possible mechanisms for induction of chromosome damage by CMV are discussed.     

Identification of MEN1 gene mutations in sporadic carcinoid tumors of the lung

Lung carcinoids occur sporadically and rarely in association with multiple endocrine neoplasia type 1 (MEN1). There are no well defined genetic abnormalities known to occur in these tumors. We studied 11 sporadic lung carcinoids for loss of heterozygosity (LOH) at the locus of the MEN1 gene on chromosome 11q13, and for mutations of the MEN1 gene using dideoxy fingerprinting. Additionally, a lung carcinoid from a MEN1 patient was studied. In four of 11 (36%) sporadic tumors, both copies of the MEN1 gene were inactivated. All four tumors showed the presence of a MEN1 gene mutation and loss of the other allele. Observed mutations included a 1 bp insertion, a 1 bp deletion, a 13 bp deletion and a single nucleotide substitution affecting a donor splice site. Each mutation predicts truncation or potentially complete loss of menin. The remaining seven tumors showed neither the presence of a MEN1 gene mutation nor 11q13 LOH. The tumor from the MEN1 patient showed LOH at chromosome 11q13 and a complex germline MEN1 gene mutation. The data implicate the MEN1 gene in the pathogenesis of sporadic lung carcinoids, representing the first defined genetic alteration in these tumors.      

Effect of Age on the Disposition and Tissue Clearances of Fluorinated Pyrimidines in Rats

The age dependency of the elimination and tissue clearances of 5-fluorouracil (FU) and its nucleoside analog, 5-deoxy-5-fluorouridine (dFUR), was investigated in 2 to 12 months old female Fischer rats. In all age groups, the blood clearances of dFUR at infusion rates of 500 and 750 mg kg^–1 day^–1 and of FU at 25 and 35 mg kg^–1 day^–1 were independent of the dose; however, the clearance of FU at a higher infusion rate of 50 mg kg^–1 day^–1 was significantly lower than at 25 mg kg^–1 day^–1. An inverse relationship between animal age and clearance was observed for dFUR at both 500 and 750 mg kg^–1 day^–1 doses, and for FU at the 50 mg kg^–1 day^–1 dose. By contrast, the FU clearance at the 25 and 35 mg kg^–1 day^–1 doses was independent of age. To examine the age effect on the metabolic activities of major eliminating organs, the metabolism of dFUR by liver and small intestine in young and old rats was compared using 13,000 × g supernatant fractions of the tissue homogenates. Data were computer-fitted to the Michaelis-Menten equation. The Km for both tissues of both age groups was approximately 120 µg ml^–1. The intrinsic clearance (Vmax/Km) of dFUR was 5 ml kg^–1 min^–1 in the liver and 8 ml kg^–1 min^–1 in the intestine. The intestinal intrinsic clearance was independent of animal age, but the hepatic intrinsic clearance was significantly decreased in the older rats. The blood concentrations of FU derived as a metabolite from dFUR were also dependent on the animal age; an elevated FU concentration was associated with a lower dFUR metabolic clearance in the old rats. These data indicate that the elimination of FU and dFUR in rats is age-dependent, and that the systemic concentration of FU, a determinant of dFUR selectivity, is elevated in older animals.     

Inhibition of Intestinal Pyrimidine Nucleoside Phosphorylases

The activity of 5-deoxy-5-fluorouridine (dFUR) depends on its activation to 5-fluorouracil (FU) by pyrimidine nucleoside phosphorylases. These enzymes are found in tumors and normal tissues, with the highest activity in the small intestines. The present study examined the inhibition of dFUR phosphorolysis in intestinal tissues. dFUR metabolism in intestinal homogenates was inhibited by uracil (U), uridine (UR), and thymidine (TdR), which are the normal substrates for the phosphorylases. Conversely dFUR reduced the metabolism of these inhibitors. A good agreement was found between the observed data and the computer-fitted data using the equations for competitive inhibition between dFUR and the inhibitors. In the absence of inhibitors, the V _max of dFUR phosphorolysis was 47.1 ± 4.9 µM/min and the apparent K _m was 910 ± 167 µM. The V _max was unaltered by the inhibitors, while the K _m was increased with increasing inhibitor concentrations. The maximal inhibition of dFUR metabolism by UR and TdR was about 80%. The K _i,'s were 372 µM for U, 87.2 µM for UR, and 112 µM for TdR and are orders of magnitude higher than their reported endogenous serum concentrations. The rate of dFUR phosphorolysis to FU in the intact intestinal epithelial crypt cells, indicated by the ratio of FU to dFUR in the intracellular fluid, was reduced by UR in a concentration-dependent fashion. These data indicate that the naturally occurring pyrimidines inhibit competitively the dFUR metabolism by the intestinal phosphorylases, that this inhibition occurs at concentrations much higher than the circulating endogenous levels, and that phosphorolysis is the major route of dFUR metabolism.     

Emergency surgery comparison of right versus left acute colonic diverticulitis: A 10-year outcome analysis

IntroductionThe difference in outcome between right (RCD) and left colonic diverticulitis (LCD) is not well established. The aim of this study was to analyse the presentation and surgical outcome of RCD versus left-sided disease following emergency surgery.MethodWe conducted a retrospective review of patients presenting with acute diverticulitis over a 10-year period from 2004 to 2014 to a tertiary unit. Patient demographics, Hinchey classification, need for emergency surgery, perioperative outcome and recurrence were evaluated.ResultsIn total 360 patients presented with acute diverticulitis, 218 (61%) were right-sided and 142 (39%) were left-sided. The mean age (57 yrs vs 68 yrs) and median length of stay (4 days vs 5 days) were significantly less in RCD (p < 0.001). The need for emergency surgery was similar between RCD and LCD (30.7% vs 23.2%, p = 0.12). Sixty-seven (31%) patients with RCD required emergency surgery, 42 (62.7%) of these were based on a presumptive diagnosis of appendicitis and underwent laparoscopic appendicectomy only. Operative morbidity (10.4% vs 51.5%, p < 0.001) and mortality were significantly higher in LCD (1.5% v 15.2%, p = 0.007). Subgroup analysis of non-appendicectomy, RCD patients, showed LCD were more likely to require surgery (11.5% vs 23.2%, p = 0.003). There was no difference in recurrence (p = 0.6).ConclusionRight colonic diverticulitis patients are younger and disease course is more benign compared to LCD. Presentation can be confused with appendicitis without proper imaging. In the rare cases where emergency surgery is required, RCD is associated with a lower operative morbidity and mortality compared to left-sided disease.     

Suture patterns and corneal graft rotation in the cadaver eye

Torque and antitorque running sutures as described by Eisner are commonly used in penetrating keratoplasty. We tested the rotational effect of three different 16-bite running suture patterns on eight cadaver eyes, with the following results: (1) the torque pattern rotates the corneal graft counterclockwise by 0.7 +/- 0.1 mm at the wound or 11 degrees; (2) the antitorque pattern rotates the corneal graft clockwise by 0.7 +/- 0.1 mm at the wound or 11 degrees; (3) an intermediate "no torque" pattern, the bites of which form an isosceles triangle, produces no rotational effect. We recommend the use of a "no torque" pattern to minimize corneal graft rotation.     

带有蛋白转导结构域的bcr/abl癌蛋白片段表达及其跨膜转运

0　引言　人类免疫缺陷病毒 (human immunodeficiencyvirus,HIV) - 1编码的反式激活蛋白 TAT具有独特的跨膜运转方式 ,而且有转导速度快 ,效率高的特点 ,被称为蛋白转导结构域 (protein transduction domain,PTD) [1 ,2 ] .本研究用PCR扩增了慢性粒细胞白血病慢粒 bcr/ abl融合蛋白的基因片段 ,在其 5′端融合 PTD结构域的编码区后在大肠杆菌中进行了表达 .表达产物经纯化后 ,加入培养的 HL 6 0细胞 ,表达的蛋白可直接进入细胞内 .这一结果为用外源蛋白负载(L oading)免疫细胞提供了新的途径 .1　材料和方法1.1　 DNA重组　人工合…     

Use of Drug Kinetics in Dermis to Predict in VivoBlood Concentration After Topical Application

Purpose. To use the drug kinetics in dermis to predict the in vivo blood concentration after topical administration. Methods. A two-step pharmacokinetic model was established. The first step was to calculate the drug input rate or flux from the skin to the systemic circulation using the drug kinetic parameters in dermis. These parameters include (a) distance over which the drug concentration declines by 50%, (b) drug concentration at the epidermal-dermal junction, and (c) minimal plateauing drug concentration in the muscle layer. These parameters were experimentally determined from the drug concentration-tissue depth profiles in the dermis, after the application of a topical dose of ddI (200 mg/kg) to rats. The second step was to use the drug input rate together with the systemic disposition pharmacokinetics of ddI in rats to predict the plasma concentration-time profiles. The model-predicted plasma concentration-time profiles were compared with the observed profiles, to determine the validity of the proposed pharmacokinetic model. Results. The observed steady state concentration (C_ss) in individual animals (n = 6) deviated from the predicted values by 3 to 55% with 3 of 6 rats showing a <15% deviation. The mean observed C_ss of all animals deviated from the mean predicted values by less than 15%. Conclusions. The close agreement between the observed and the model-predicted drug concentrations indicates that the systemic drug input can be calculated from the drug kinetics in the dermis.