Priming effects with drugs and other reinforcers.

Abstinent drug users often report that taking even a small amount of their previously abused drug increases their desire for the drug and can lead to a full relapse. This apparent "priming" effect of drugs has been studied in both laboratory animals and humans. In animals trained to self-administer drugs, small amounts of a previously self-administered drug readily reinstate responding. In humans, administration of a previously abused drug increases self-reported craving and desire for the drug. Priming effects also occur with other reinforcers (e.g., presentation of a food stimulus increases food-reinforced responding). This article examines the generality of priming phenomena, and it examines some of the learned or unlearned processes that underlie the effect. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Melanoma in pregnancy

The incidence of pregnancy complicated by melanoma of the skin, calculated from data of the Netherlands Cancer Registry, is 1 per 10,000 pregnancies. The prognosis of a melanoma is not affected by prior or subsequent pregnancy. A melanoma diagnosed during pregnancy does appear to have a more unfavourable prognosis, due not to a less favourable clinical course, but to a delay in diagnosing melanoma during pregnancy and (or) a less favourable site. When a pregnancy is complicated by malignancy, in case of a melanoma there is a higher risk of placental metastasis compared with other malignancies. In nearly 50% of the cases reported in literature of placental metastasis there was foetal involvement.     

Preface

The diffusion of platinum and gold in nickel at relatively low temperatures (250–725 °C) was measured by Rutherford backscattering spectrometry (RBS). The diffusion profile of the noble metal in nickel was calculated from RBS spectra. This method takes fully into account the dependence of the energy losses of the backscattered particle along the inward and outward paths on the changing energy of the particle and the changing composition of the target. Diffusion coefficients are calculated from the measured diffusion profile. The dependence of the diffusion coefficient on temperature obeys the Arrhenius law. The activation enthalpies are 78.2 kJ mol^-1 and 119.6 kJ mol^-1 for the diffusion of platinum and gold respectively into nickel. The frequency factors are respectively 2.6 × 10^?9cm²s^?1 and 1.4 × 10^?7cm²s^?1. Experimental data suggest that diffusion along the grain boundaries is 2–3 times as fast as bulk diffusion.     

An alternative route for multistep tumorigenesis in a novel case of hereditary renal cell cancer and a t(2;3)(q35;q21) chromosome translocation

Through allele-segregation and loss-of-heterozygosity analyses, we demonstrated loss of the translocation-derivative chromosome 3 in five independent renal cell tumors of the clear-cell type, obtained from three members of a family in which a constitutional t(2;3)(q35;q21) was encountered. In addition, analysis of the von Hippel-Lindau gene, VHL, revealed distinct insertion, deletion, and substitution mutations in four of the five tumors tested. On the basis of these results, we conclude that, in this familial case, an alternative route for renal cell carcinoma development is implied. In contrast to the first hit in the generally accepted two-hit tumor-suppressor model proposed by Knudson, the familial translocation in this case may act as a primary oncogenic event leading to (nondisjunctional) loss of the der(3) chromosome harboring the VHL tumor-suppressor gene. The risk of developing renal cell cancer may be correlated directly with the extent of somatic (kidney) mosaicism resulting from this loss.     

Preoperative biliary drainage, colonisation of bile and postoperative complications in patients with tumours of the pancreatic head: a retrospective analysis of 241 consecutive patients

OBJECTIVE: To analyse the outcome of preoperative biliary drainage in patients being operated on for a tumour in the pancreatic head. DESIGN: Retrospective study. SETTING: University hospital, The Netherlands. SUBJECTS: Consecutive series of 241 patients. MAIN OUTCOME MEASURES: Decline in bilirubin concentrations and bacterial contamination of bile as a result of preoperative drainage. Incidence of postoperative complications in patients who underwent preoperative drainage and those who did not. RESULTS: 184/241 patients underwent preoperative biliary drainage. Endoscopic drainage was the most effective, shown by a median reduction in bilirubin concentrations of 82%, 74%, and 50% after endoscopic drainage (n = 149), papillotomy (n = 25) and external drainage (n = 10), respectively. Bacterial contamination of bile was significantly more common when an endoprosthesis was used, but did not result in a higher rate of infective complications. 163 Whipple's resections, 33 total pancreatectomies, and 45 biliary-enteric bypasses were performed. 137/241 (57%) patients had postoperative complications. There was no significant difference in the incidence of postoperative complications between patients who had preoperative biliary drainage and those who did not (p = 0.4).     

Determination of the ash yield and the mineral matter content of brown coals by density measurements

A method of measuring the density of bed-moist brown coals based on their plastic properties is described and the feasibility of using the method for determination of the ash yield of the coal is evaluated.     

Image buildup for the rectangular waveguide tensor Green's function

Tensor Green's functions, of both electric and magnetic type, are produced for the rectangular waveguide through summation of a doubly infinite series of free-space contributions obtained from endless imaging across (perfectly conducting) guide walls. The requisite summation is facilitated by resorting to a Fourier integral representation for the basic free-space kernel, followed by appeal to the Poisson summation formula. That latter, in particular, engenders, through Dirac delta function appearance, an automatic decomposition into waveguide modes. Indication is further made as to how the imaging method may naturally be extended to assemble mode-decomposed Green's functions in an axially bounded, rectangular cavity.     

Immunological and functional characterization of Mycobacterium leprae protein antigens: an overview

A major focus of leprosy research in the last 10 years has been the identification and characterization of antigens of Mycobacterium leprae that interact with antibodies and T cells of the host's immune response. Through the combined efforts of many different laboratories, a substantial number of protein antigens have been identified and characterized. In this MicroReview we present an updated list of M. leprae protein antigens, and, with emphasis on recent developments, summarize what is known regarding their functional and immunological features.