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The detection of regions of heterochromatin has been the subject of intense investigation. We investigated an adaptation of the commonly used technique by replacing the nonfluorescent dye, Giemsa, by a fluorescent one, propidium iodide. This adaptation produces greater contrast of the heterochromatic bands in metaphase chromosomes and can be especially valuable when the organisms studied possess heterochromatin that is pale and difficult to visualize. We discuss the interactions of these two dyes with DNA and the excitation of the fluorescent dye when irradiated with ultraviolet light.

A cemented Charnley total hip prosthesis was implanted in a 48-year-old man with mild haemophilia (factor VIII 4 IU dL-1) in his right spontaneously ankylosed hip. At the time of surgery he was anti-HCV positive, anti-HIV negative, and no circulating inhibitors were encountered. The indication for surgery was long-lasting intractable low back and ipsilateral knee pain. At 4-month follow-up, relief of pain was achieved as well as correction of limb-length discrepancy, with a good result according to the Mayo Clinic hip score. Doses of 50 IU kg-1 body weight of recombinant factor VIII (Recombinate; Baxter, Glendale, California, USA) was used during the 2 weeks of admittance to the hospital. The dosage was adjusted according to the recoveries of factor VIII, with an overall factor consumption of 68 000 IU. As far as we know this is the first case reported in the literature of a person with haemophilia in whom a spontaneous hip ankylosis has been satisfactorily converted in a total hip arthroplasty with a short-term follow-up. However, a much longer follow-up is still needed to ascertain the efficacy of this surgical procedure in haemophilia.

Atrial fibrillation (AF) and flutter are common following cardiac surgery, increasing costs and morbidity. Cardiologists need a method to discern those patients who are at high risk for this arrhythmia in order to attempt to treat them by either pharmacologic or non-pharmacologic means. We performed a retrospective analysis of 377 CABG patients, of which 94 developed AF post-operatively. Feature selection and AF occurrence prediction was performed using a multivariate regression model, and two rough set derived rule classifiers. The rough set derived feature subset performed best with an accuracy of 87%, a sensitivity of 58.5%, and a specificity of 96.5%. This shows the importance of testing feature subsets, thereby discouraging the practice of simply combining the best individual predictors. The utility of rough set theory in prediction of cardiac arrhythmia is also validated.

Polymerase chain reaction (PCR) amplification of T-cell receptor-gamma gene rearrangement was used for molecular staging in a case of primary cutaneous T-cell lymphoma (CTCL) with fatal evolution. Although initial evaluation was negative for systemic involvement, the patient died due to heart failure. Autopsy findings revealed lymphomatous myocardial infiltration, but other tissues and organs examined, including lymph nodes, liver, spleen, lung and bone marrow, appeared to be free of disease. Molecular analysis from frozen samples obtained during the initial evaluation, as well as paraffin-embedded material obtained during autopsy, revealed the presence of clonal rearranged bands in all tissues examined except the bone marrow. Subsequent hybridization of PCR products with a tumour-specific oligoprobe confirmed the PCR results, suggesting widespread dissemination of the lymphomatous process. The use of molecular analysis can add significant information about the extent of disease in patients with CTCL and may be helpful in the establishment of therapeutic options.

Retinoic acid (RA) plays major roles during nervous system development, and during regeneration of the adult nervous system. We have previously shown that components of the RA signaling pathway are upregulated after optic nerve injury, and that exogenous application of all-trans retinoic acid (ATRA) greatly increases the survival of axotomized retinal ganglion cells (RGCs). The objective of the present study is to investigate the effects of ATRA application on the macrophages in the optic nerve after injury, and to determine whether this affects axonal regeneration. The optic nerve was crushed and treated with PBS, ATRA and/or clodronate-loaded liposomes. Nerves were examined at one and two weeks after axotomy with light microscopy, immunocytochemistry and electron microscopy. ATRA application to the optic nerve caused transient increases in the number of macrophages and microglia one week after injury. The macrophages are consistently labeled with M2-type markers, and have considerable phagocytic activity. ATRA increased ultrastructural features of ongoing phagocytic activity in macrophages at one and two weeks. ATRA treatment also significantly increased the numbers of regenerating GAP-43-labeled axons. Clodronate liposome treatment depleted macrophage numbers by 80%, completely eliminated the ATRA-mediated increase in axonal regeneration, and clodronate treatment alone decreased axonal numbers by 30%. These results suggest that the success of axon regeneration is partially dependent on the presence of debris-phagocytosing macrophages, and that the increases in regeneration caused by ATRA are in part due to their increased numbers. Further studies will examine whether macrophage depletion affects RGC survival.

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