Molecular genetic methods in the diagnosis of hematologic neoplasms

Leukemias and lymphomas are monoclonal neoplasms that arise as a result of molecular abnormalities. These abnormalites are diverse but can be grouped into two general categories, chromosomal translocations that usually result in oncogene activation and inactivation of tumor suppressor genes. Recent advances in our understanding of chromosomal translocations have led to improved classification of leukemias and lymphomas. For example, the t(9;22)(q34;q11) is now considered a defining feature of chronic myeloid leukemia, and the t(2;5)(p23;q35) defines a clinically and biologically unique subset of anaplastic large cell lymphomas. In this review, we focus on chromosomal translocations in hematologic neoplasms and the techniques used for their detection. We also briefly discuss tumor suppressor genes and assessment of clonality in lymphoid neoplasms.     

GeneID in Drosophila

GeneID is a program to predict genes in anonymous genomic sequences designed with a hierarchical structure. In the first step, splice sites, and start and stop codons are predicted and scored along the sequence using position weight matrices (PWMs). In the second step, exons are built from the sites. Exons are scored as the sum of the scores of the defining sites, plus the log-likelihood ratio of a Markov model for coding DNA. In the last step, from the set of predicted exons, the gene structure is assembled, maximizing the sum of the scores of the assembled exons. In this paper we describe the obtention of PWMs for sites, and the Markov model of coding DNA in Drosophila melanogaster. We also compare other models of coding DNA with the Markov model. Finally, we present and discuss the results obtained when GeneID is used to predict genes in the Adh region. These results show that the accuracy of GeneID predictions compares currently with that of other existing tools but that GeneID is likely to be more efficient in terms of speed and memory usage.     

Experimental infection of immunomodulated NOD/LtSz-SCID mice as a new model for Plasmodium falciparum erythrocytic stages

The main objective of this study was to determine whether a chemical immunomodulation protocol could reduce the resistance of NOD/LtSz-SCID mice to Plasmodium falciparum infection and provide an improved mouse model for screening the antimalarial activity of new compounds. This model was compared with the presently used immunodeficient Beige/Nude/Xid (BNX) mouse model, using the same protocol, in terms of percentage of infected mice, parasite development, leukocyte response and phagocytosis of P. falciparum infected cells in various organs. Our results show that the combination of the chemical immune modulation protocol with the genetic background of NOD/LtSz-SCID mice results in the development of long-lasting P. falciparum infection in a high percentage of mice. A comparison of the results obtained in the histological study for both mouse models suggests that the higher rate of success in NOD/LtSz-SCID mice could be related to the reduced macrophage recruitment developed in different tissues to remove the parasite from blood.     

Myelolipoma: A New Adrenal Finding in Carney's Complex?

Pigmented nodular cortical hyperplasia, a rare cause of Cushing’s syndrome, is characterized by resistance to inhibition with dexamethasone and normal sized adrenal glands with multiple, small pigmented nodules. The disorder may be a component of a syndrome inherited as an autosomal dominant pattern that includes intra- and extracardiac myxomas, lentiginous lesions, blue nevi, other functional endocrine tumors, and peripheral nerve tumors (Carney’s complex). We report a patient in whom bilateral myelolipomas were found, in addition to the usual features of this complex. A 29-yr-old man was admitted to the hospital for Cushing’s syndrome of probably more than 15 yr duration. Physical examination showed diffuse facial hyperchromatic macules, 0.2–0.5 cm, predominantly around the lips and on the palmar surfaces of the fingers. Results with dexamethasone suppression nocturnal testing (1 and 8 mg) were compatible with an adrenal adenoma. The computed tomography (CT) of the sella turcica was normal. Adrenal CT showed a tumor in the left gland with a double component: one solid and another suggestive of fat, consistent with an angiomyelolipoma. Following 5 wk treatment with ketoconazole, 800 mg per day po, serum cortisol decreased to 5.9 μg/dL, morning and evening, respectively. Bilateral adrenalectomy was performed. Pathologic examination revealed pigmented nodular cortical hypersplasia and a dominant myelolipoma in the left adrenal. A microscopic myelolipoma was identified in the right adrenal. An echocardiogram showed a mass on the posterior wall of the left ventricle which was a myxoma. Study of the patient's family disclosed two sisters with facial lentigines. Echocardiograms were performed on all available first degree relatives: all were normal. Nocturnal inhibition with dexamethasone revealed that one of the patient’s sisters with lentigines also had hypercortisolism. Myelolipoma has been reported in association to Cushing syndrome in humans and experimentally after pituitary extracts in animals. The relationship between this finding and the Carney’s complex remain elusive.     

Differential uptake of systemic fluorochrome Hoechst 33342 in lung and liver metastasis of B16 melanoma

Summary The growth and vascularization patterns of B16 melanoma colonies in the liver and lungs were measured and compared by histological techniques and dye diffusion patterns after injection of the fluorochrome Hoechst 33342. In the liver, the fluorescent pattern of dye diffusion revealed that uninodular tumours measuring up to 146 n in diameter were not functionally vascularized. However, when the nodules fused to give rise to multinodular tumours measuring between 256 and 366 n in diameter, a reticular dye diffusion pattern revealed functional tumour vascularization. In the lungs, subpleural, parenchymal and peritubular (i.e. surrounding blood vessels and airways) tumours were observed. The two former classes were vascularized down to thicknesses and diameters of 49 and 24 m respectively. In contrast, dye diffusion was never seen in peritubular tumour cuffs up to 609 m in thickness. The results indicate differences in vascularization patterns in B16 tumours in the liver and lungs, and differences between tumours growing in different sites within the lungs. If these results are applicable to metastases in these two organs, they indicate potential diffusion-mediated resistance to chemotherapy, and potential hypoxia-mediated resistance to radiotherapy of both metastases and micrometastases.     

Functional insights on the polarized redistribution of leukocyte integrins and their ligands during leukocyte migration and immune interactions

Summary:  Cell–cell and cell–matrix interactions are of critical importance in immunobiology. Leukocytes make extensive use of a specialized repertoire of receptors to mediate such processes. Among these receptors, integrins are known to be of crucial importance. This review deals with the central role of integrins and their counterreceptors during the establishment of leukocyte–endothelium contacts, interstitial migration, and final encounter with antigen-presenting cells to develop an appropriate immune response. Particularly, we have addressed the molecular events occurring during these sequential processes, leading to the dynamic subcellular redistribution of adhesion receptors and the reorganization of the actin cytoskeleton, which is reflected in changes in cytoarchitecture, including leukocyte polarization, endothelial docking structure formation, or immune synapse organization. The roles of signaling and structural actin cytoskeleton-associated proteins and organized membrane microdomains in the regulation of receptor adhesiveness are also discussed.     

Prevalence of obesity and hyperinsulinemia: its association with serum lipid and lipoprotein concentrations in healthy individuals from Maracaibo,Venezuela

The aim of this study was to analyse the prevalence of obesity and hyperinsulinemia and their association with lipid profile alterations on apparently healthy individuals from Maracaibo, Venezuela. We evaluated 306 men and 41 women, ages ranging from 33 to 65 years. All subjects underwent cardiovascular evaluation and laboratory examination after 10-12 h fasting, for glycaemia, total cholesterol, TG, VLDL-C, LDL-C and HDL-C as well as insulin. Seventy-four percent of men and 56.1% of women showed obesity (BMI > 25 Kg/m2). Men showed high concentrations of TG (48.3%), total cholesterol (40.2%), VLDL-C (48.3%) and LDL-C (33.9%) and low HDL-C levels (48%). The most frequent alteration on the lipid profile in women was high total cholesterol (46%) and LDL-C (51.2%). Men had significantly higher insulin concentrations than women (p < 0.005). After they were classified as obese or non obese, the obese subjects (men and women) showed higher prevalence of lipid profile alterations and insulin concentrations than non obese. The insulin concentration in obese men correlated with BMI, TG, VLDL-C and HDL and, in women with BMI, TG and VLDL-C. In conclusion, a high percentage of men and women in this study showed obesity and this obesity, specially in men, was strongly associated with lipid profile alterations and high insulin concentrations both well known cardiovascular risk factors.     

Learned immobility explains the behavior of rats in the forced swimming test

The rat forced-swimming test (FST) is widely used for screening substances with a potential antidepressant effect. The rat immobility shown in the FST has been interpreted as "behavioral despair" and has been suggested as an animal model of human depression. In the following series of experiments it is shown that measuring rat mobility by an automatic recording device is more accurate than measuring immobility time by direct observation (Experiment 1 and 5). The automatic recording procedure was tested with imipramine and mianserin showing similar results to those reported in the literature using a direct observation procedure by the researcher (Experiment 2). In Experiment 3 it was demonstrated that: (a) rat mobility decreased with experience, (b) switching water depth on Day 2 of the test increased mobility and (c) anisomycin acts as a false positive. In Experiment 4 the possible state dependent effect of imipramine in the FST was studied. The effect of imipramine on rat behavior in the FST is not state dependent. The imipramine-saline group shows greater mobility than the saline-saline group and does not differentiate from the imipramine-imipramine group. Thus, it was suggested that imipramine could interfere with the acquisition and/or consolidation processes. In Experiment 5, it is shown that a single dose of 25 mg/kg of imipramine, administered before or immediately after training on Day 1, increases rat's mobility on Day 2, thus suggesting that imipramine alters the consolidation process. From these results it is suggested that the behavioral process involved in the FST is "learning to be immobile" instead of "behavioral despair" as previously suggested in the literature.