DNA & Cromossomos

Gene Amplification

Clique em Interessante para acessar a referência bibliográfica:

• Interessante: Molecular pathology and future developments. Going JJ, Gusterson BA Department of Pathology, University of Glasgow, Glasgow Royal Infirmary. going@udcf.gla.ac.uk There has already been a 'molecular' revolution in pathology. Demonstrating transcription of specific single genes or small gene sets and their protein products by in situ hybridisation and immunocytochemistry is routine in diagnostic and experimental pathology. A perhaps-greater revolution is imminent with the application of more recently established and emergent technologies in pathology. These include new approaches to polymerase chain reaction (PCR); simultaneous studies of multiple genes and their expression using oligonucleotide and cDNA arrays; serial analysis of gene expression (SAGE); expressed sequence tag (EST) sequencing, subtractive cloning and differential display; high-throughput sequencing; comparative genomic hybridization, multiplex fluorescence in situ hybridisation (FISH) (spectral karyotyping); reverse chromosome painting; knockout and transgenic organisms; laser microdissection and micro-machining; and new methods in bio-informatics, 'data mining' and data visualisation. Molecular methods will profoundly change diagnosis, prognosis and treatment targeting in oncology and elucidate fundamental mechanisms of neoplastic transformation. Individual susceptibility to specific diseases will become assessable and screening will be refined. The new molecular biology will be most fruitful in partnership with classical approaches to pathology: the expectation that molecular methods alone will answer all pathological questions is unrealistic. A further challenge for the biomedical community in the 'genome era' will be to ensure that the benefits of these sophisticated technologies are enjoyed globally.
  
• Interessante: Bone marrow engraftment analysis after allogeneic bone marrow transplantation. Van Deerlin VM, Leonard DG Department of Pathology and Laboratory Medicine, University of Pennsylvania Medical Center, Philadelphia, USA. BME analysis of allo-BMT patients is used to confirm engraftment and detect MC after transplant. With frequent monitoring, the detection of MC by BME analysis may alert clinicians to a high risk of relapse and allow early intervention with a rapid taper of immunosuppression or DLI therapy. In pancytopenic patients BME analysis can help differentiate relapse from drug toxicity or infection. Although many methods have been used for BME analysis, PCR amplification of STR loci is the choice of many clinical laboratories because it is informative, quantitative, relatively rapid, and sensitive. The sensitivity of BME analysis is dependent upon many factors that need to be optimized by the laboratory performing the analysis. Although BME analysis is complex, the clinical significance for allo-BMT patients warrants the effort to develop, validate, and perform BME analysis in support of the allo-BMT service.
  
• Interessante: Clin Lab Med 2000 Mar;20(1):105-17, ix Related Articles, Books Minimal residual disease in acute promyelocytic leukemia. Weil SC Cancer Center in Population Science, Fox Chase Cancer Center, Philadelphia, Pennsylvania, USA. scw_mail_98@yahoo.com In the last decade our understanding of acute promyelocytic leukemia (APL) has advanced tremendously. The recognition of all-trans retinoic acid (ATRA) as a powerful therapeutic agent paralleled the cloning of the t(15;17) breakpoint. RtPCR for the PML-RARA hybrid mRNA has become the hallmark of molecular diagnosis and molecular monitoring in APL. Current techniques are useful in predicting complete remission and a possible cure in many patients who repeatedly test negative by PCR. Standardizing techniques and improving the sensitivity of the assay are important. Doing this in a way so that clinically relevant minimal residual disease can be distinguished from "indolent disease" remains among the future challenges in APL.
  
• Interessante: Pediatr Clin North Am 2000 Feb;47(1):39-63 Related Articles, Books, LinkOut Diagnosis of HIV infection in children. Nielsen K, Bryson YJ Department of Pediatrics, University of California, Los Angeles, School of Medicine, USA. Many advances have been made in the area of HIV diagnostics. Commercially available virologic assays are sensitive and specific for the early detection of HIV in perinatal infection. The timing of the transmission of HIV from mother to child (in utero, at the time of birth, or postnatally by breast-feeding) is a critical consideration in the appropriate diagnosis of infants. Several algorithms can be used to define early infection and the potential timing of acquisition of infection that combine different assays and timing of specimens. The use of virologic assays, including HIV DNA PCR and HIV RNA detection methods and culture, can define and rule out infection in infants less than 18 months of age. Serologic diagnostic methods, including HIV ELISA, immunofluorescence, and western blot assays, can be used to diagnose infants more than 18 months of age, when transplacental antibody has disappeared in uninfected HIV-exposed infants. The challenge of the early and accurate diagnosis of perinatally HIV-exposed infants is the use of new assays to detect different HIV subtype infections that are prevalent in developing countries. Rapid, simple, and inexpensive serologic and virologic assays are being developed for worldwide use.
  
• Interessante: Urol Clin North Am 2000 Feb;27(1):115-23, x Related Articles, Books, LinkOut Telomerase in human bladder cancer. Liu BC, Loughlin KR Division of Urology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA. DrLiu@aol.com Biomarkers for human bladder cancer are currently available and more are being developed. However, the ultimate goal of diagnosing bladder cancer consistently in a noninvasive fashion has not yet been achieved. Telomerase is an enzyme that may play a role in maintaining telomere sequences in the ends of chromosomes and its activity may reflect the presence of immortal or cancer cells. In this article, we reviewed the potential applications of telomerase in the diagnosis, monitoring, and treatment of human bladder cancer.
  
• Interessante: nt J Biochem Cell Biol 2000 Feb;32(2):157-70 Related Articles, Books Role of reactive oxygen species in apoptosis: implications for cancer therapy. Mates JM, Sanchez-Jimenez FM Department of Molecular Biology and Biochemistry, Sciences Faculty, University of Malaga, Campus de Teatinos, Malaga, Spain. jmates@uma.es Reactive oxygen species are widely generated in biological systems. Consequently humans have evolved antioxidant defence systems that limit their production. Intracellular production of active oxygen species such as *OH, O2- and H2O2 is associated with the arrest of cell proliferation. Similarly, generation of oxidative stress in response to various external stimuli has been implicated in the activation of transcription factors and to the triggering of apoptosis. Here we review how free radicals induce DNA sequence changes in the form of mutations. deletions, gene amplification and rearrangements. These alterations may result in the initiation of apoptosis signalling leading to cell death, or to the activation of several proto-oncogenes and or the inactivation of some tumour suppressor genes. The regulation of gene expression by means of oxidants, antioxidants and the redox state remains as a promising therapeutic approach. Several anticarcinogenic agents have been shown to inhibit reactive oxygen species production and oxidative DNA damage, inhibiting tumour promotion. In addition, recombinant vectors expressing radical-scavenging enzymes reduce apoptosis. In conclusion, oxidative stress has been implicated in both apoptosis and the pathogenesis of cancer providing contrived support for two notions: free radical reactions may be increased in malignant cells and oxidant scavenging systems may be useful in cancer therapy.
  
• Interessante: Am J Surg Pathol 2000 Feb;24(2):296-301 Related Articles, Books Spontaneously relapsing clonal, mucosal cytotoxic T-cell lymphoproliferative disorder: case report and review of the literature. Ranheim EA, Jones C, Zehnder JL, Warnke R, Yuen A Department of Pathology, Stanford University Medical Center, CA 94305, USA. Primary T-cell lymphoma of the gastrointestinal tract is a rare and usually aggressive disorder that may be associated with celiac disease. The authors describe a unique case of a clonal proliferation of CD8+ T cells involving the oral mucosa, ileum, and colon of a 35-year-old man that has regressed spontaneously and recurred numerous times over a 9-year period without treatment. The patient's symptoms were limited to occasional rectal bleeding and recurring painful oral ulcers. Within the intestine, these collections of small T cells induced minimal architectural distortions and did not show extensive epitheliotrophism. Polymerase chain reaction and sequencing analyses revealed that the identical T-cell clone has been present for more than 9 years and in different mucosal locations in this patient. This may represent a unique T-cell lymphoproliferative process akin to a mucosal counterpart of lymphomatoid papulosis of the skin.
  
• Interessante: Acta Medica (Hradec Kralove) 1999;42(3):85-8 Related Articles, Books Minimal residual disease, its detection and significance in hairy-cell leukemia. Zak P, Chrobak L, Dedic K Department of Clinical Haematology, University Teaching Hospital, Hradec Kralove. zakpavel@fnhk.cz As minimal residual disease (MRD) is considered the detection of hairy cells (HCs) in a patient with hairy cell leukemia (HCL) in complete remission with the absence of detectable HCs by routine morphology of peripheral blood, aspirates and bone marrow core sections, using more sensitive methods of identification as immunohistological staining or polymerase chain reaction (PCR) to detect immunoglobulin heavy chain genes rearrangement. Various monoclonal antibodies (MoAbs) as CD20, DBA.44, B ly-7, HC2, CD25 and CD11c have been applied using immunological staining. There is no standardized technique for identification of MRD. According to the technique used the MRD has been detected in 13% to 100% of patients in complete remission (CR). It may be concluded that many patients, if not all, in stable CR may have residual HCs. Whether MRD will have impact on early relapse or on long term outcome, or whether patients in CR with persistent MRD will remain so, is a matter of a longer follow-up.
  
• Interessante: Mol Diagn 1999 Dec;4(4):353-64 Related Articles, Books Clinical, genetic, and pharmacogenetic applications of the Invader assay. Kwiatkowski RW, Lyamichev V, de Arruda M, Neri B Third Wave Technologies, Inc, Madison, Wisconsin 53719, USA. bkwiatkowski@twt.com The Invader technology has been developed for the detection of nucleic acids. It is a signal amplification system able to accurately quantify DNA and RNA targets with high sensitivity. Exquisite specificity is achieved by combining hybridization with enzyme recognition, which provides the ability to discriminate mutant from wild-type at ratios greater than 1/1000 (mutant/wt). The technology is isothermal and flexible and incorporates a homogeneous fluorescence readout. It is therefore readily adaptable for use in clinical reference laboratories, as well as high-throughput applications using 96-, 384-, and 1,536-well microtiter plate formats. The molecular mechanism of the system and specific applications for use in clinical and research laboratories are described. These include direct analysis of unamplified human genomic DNA to detect mutations and single-nucleotide polymorphisms associated with factor V Leiden, factor II, cystic fibrosis, and apolipoprotein E, and gene expression assays that quantify messenger RNA levels in cells using direct lysates.
  
• Interessante: Neoplasma 1999;46(5):257-66 Related Articles, Books Tumor necrosis factor-alpha: molecular-biological aspects minireview. Szatmary Z Institute of Preventive and Clinical Medicine, Department of Clinical Immunology, Bratislava, Slovak Republic. Tumor necrosis factor-alpha (TNF-alpha) a proinflammatory cytokine with multiple actions was first identified for its anticancer activity. However, TNF-alpha has a beneficial function in activation of host defense, its uncontrolled production can lead to pathological consequences. At the cellular level, it is able to exert obviously opposing effects: apoptosis and activation. It modulates survival and activates genes through various intermediates, including protein kinases, protein phosphatases, reactive oxygen intermediates, phospholipases, proteases, sphingomyelinases and transcription factors. In this review, the INF-alpha is characterized at the molecular and cellular level (TNF-alpha mediated signal transduction is discussed in the first part, regulation of its expression in the second one), as well as methods of its determination in biological materials, giving special emphasis to the molecular-biological approach. The full understanding of the molecular mechanism of TNF-alpha will provide the basis for a pharmacological approach intended to inhibit or potentiate selected biological actions of this cytokine.

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