Pro-megakaryoblasts in bone marrow tissue from patients with primary (idiopathic) osteo-myelofibrosis (agnogenic myeloid metaplasia). An immunomorphometric study on trephine biopsies

An immunomorphometric study was performed on bone marrow biopsies from 40 patients with primary osteomyelofibrosis--OMF, (agnogenic myeloid metaplasia) by employment of a monoclonal antibody against glycoprotein IIIa (Y2/51) to determine the number of pro-megakaryoblasts. Specimens from 15 individuals without any hematological disorder served as controls. With reference to the pertinent literature on megakaryocyte precursors and following a pilot study on corresponding smears, in tissue sections pro-megakaryoblasts were characterized by a size of 42.1 +/- 2.6 microns 2 (diameter 7.5 +/- 0.3 microns). In comparison with controls, in OMF no relevant increase in the number of pro-megakaryoblasts per square and cubic millimeter bone marrow was evaluable. The relative frequency of these precursors was significantly reduced due to an increase in the total amount of conspicuously large and abnormal megakaryocytes. Statistical analysis failed to reveal any correlations between counts for pro-megakaryoblasts or the total number of Y2/51--positive megakaryocytic elements with the density of argyrophilic fibers (determined by morphometry) or the platelet values. Our findings imply that in OMF the marked increase in circulating progenitor cells of the megakaryocyte lineage may be generated by extramedullary, probably splenic hematopoiesis. Moreover, the evolution of medullary fibrosis is thought to be associated with the striking predominance of large atypical, possibly overaged and hyperpolyploid megakaryocytes and not with an increase in precursor cells.     

Treatment of AIDS-related cutaneous Kaposi's sarcoma with topical alitretinoin (9-cis-retinoic acid) gel. Panretin Gel North American Study Group

BACKGROUND: Kaposi's sarcoma (KS) is the most frequent malignancy in patients with HIV. Given the promise that retinoids show in the treatment of various hyperproliferative skin disorders and in vitro evidence of inhibition of proliferation of KS cells, a randomized, controlled clinical trial was conducted. METHODS AND RESULTS: A 12-week, multicenter, randomized, double-blind, vehicle-controlled safety and efficacy evaluation of topical alitretinoin 0.1% gel applied to cutaneous KS lesions was conducted in HIV-infected patients. The primary efficacy endpoint was the patient's response rate, as determined by evaluating six index lesions representative of the patient's overall KS cutaneous disease using AIDS Clinical Trials Group (ACTG) response criteria applied to topical therapy. Of 268 patients entered in the blinded treatment phase of the study (alitretinoin group, n = 134; vehicle group, n = 134), 47 patients (35%) treated with alitretinoin 0.1% gel had a positive response, compared with 24 patients (18%) treated with vehicle gel. Of 184 patients receiving open-label alitretinoin treatment following the blinded phase of the trial, 90 patients (49%) met criteria for a positive response. This superior efficacy of alitretinoin gel over vehicle gel was maintained when the data were adjusted or analyzed for age, race, Kamofsky scores, baseline CD4+ lymphocyte counts, number of raised lesions at baseline, and aggregate area of index lesions. Alitretinoin 0.1% gel was superior to vehicle gel regardless of the number of concurrent antiretroviral therapies. Most adverse events were mild to moderate in severity, limited to the application site, and reversible on reduction in frequency or suspension of application. Relatively few patients (7%) discontinued alitretinoin therapy because of to related adverse events. CONCLUSIONS: The results show that alitretinoin gel application is safe and generally well tolerated, and they indicate the superiority of alitretinoin 0.1% gel over vehicle gel in the treatment of cutaneous AIDS-related KS lesions.     

Geometrically based optimization for extracranial radiosurgery

For static beam conformal intracranial radiosurgery, geometry of the beam arrangement dominates overall dose distribution. Maximizing beam separation in three dimensions decreases beam overlap, thus maximizing dose conformality and gradient outside of the target volume. Webb proposed arrangements of isotropically convergent beams that could be used as the starting point for a radiotherapy optimization process. We have developed an extracranial radiosurgery optimization method by extending Webb's isotropic beam arrangements to deliverable beam arrangements. This method uses an arrangement of N maximally separated converging vectors within the space available for beam delivery. Each bouquet of isotropic beam vectors is generated by a random sampling process that iteratively maximizes beam separation. Next, beam arrangement is optimized for critical structure avoidance while maintaining minimal overlap between beam entrance and exit pathways. This geometrically optimized beam set can then be used as a template for either conformal beam or intensity modulated extracranial radiosurgery. Preliminary results suggest that using this technique with conformal beam planning provides high plan conformality, a steep dose gradient outside of the tumour volume and acceptable critical structure avoidance in the majority of clinical cases.     

Effects of transgenes for human and bovine growth hormones on age-related changes in ovarian morphology in mice

The expression of human growth hormone (GH) in female transgenic mice (TM) is accompanied by sterility, whereas females expressing the bovine GH gene are fertile. A light and electron microscopic study was conducted to examine whether expression of these foreign GH genes in mice is associated with structural changes in the ovaries of young adult (3-month-old) or middle-aged (7-month-old) mice. One ovary was serially sectioned for light microscopy, and the contralateral ovary was used for electron microscopy. The numbers of preantral (PAF) and antral (AF) follicles, with and without signs of atresia, as well as the number of corpora lutea (CL), were determined. As expected, body weights of both young and middle-aged TM of either kind were significantly increased over those of their normal littermates. However, the ovarian weights of TM and control mice did not differ. In the 3-month-old TM, the ovaries were grossly normal at the light microscopic level. However, significantly more CL were counted in the ovaries of human GH-TM than in those of the other two groups. The percentage of PAF with signs of atresia was significantly reduced in ovaries of bovine GH-TM compared with the other groups, while the percentages of AF undergoing atresia were significantly different in all groups, with the highest values in normal animals, intermediate ones in human GH-TM, and the lowest in bovine GH-TM. In the ovaries of 7-month-old human GH-TM, conspicuous clusters of large, foamy light cells were present in the cortex and the medulla. Ultrastructurally, these cells appeared as interstitial cells in various stages of degeneration, accumulating cholesterol crystal-like inclusions. Although degeneration of interstitial cells was observed also in the other types of animals, it involved usually only single cells and no cytoplasmic crystal inclusions. Moreover, in the ovaries of 7-month-old human GH-TM the percentages of PAF were significantly reduced and the percentages of AF significantly increased compared with those in the two other groups, which did not differ from each other with respect to these parameters. No significant differences in the numbers of CL were found between the groups. Percentages of atretic PAF were significantly reduced in bovine GH-TM and comparable in the other two groups, while percentages of atretic AF were not different between normal and bovine GH-TM, but were significantly increased in human GH-TM.(ABSTRACT TRUNCATED AT 400 WORDS)     

Hematopoietic progenitor cells and cellular microenvironment: behavioral and molecular changes upon interaction

Cell-cell contact between stem cells and cellular determinants of the microenvironment plays an essential role in controlling cell division. Using human hematopoietic progenitor cells (CD34+/CD38-) and a stroma cell line (AFT024) as a model, we have studied the initial behavioral and molecular sequel of this interaction. Time-lapse microscopy showed that CD34+/CD38- cells actively migrated toward and sought contact with stroma cells and 30% of them adhered firmly to AFT024 stroma through the uropod. CD44 and CD34 are colocalized at the site of contact. Gene expression profiles of CD34+/CD38- cells upon cultivation with or without stroma for 16, 20, 48, or 72 hours were analyzed using our human genome cDNA microarray. Chk1, egr1, and cxcl2 were among the first genes upregulated within 16 hours. Genes with the highest upregulation throughout the time course included tubulin genes, ezrin, c1qr1, fos, pcna, mcm6, ung, and dnmt1, genes that play an essential role in reorganization of the cytoskeleton system, stabilization of DNA, and methylation patterns. Our results demonstrate directed migration of CD34+/CD38- cells toward AFT024 and adhesion through the uropod and that upon interaction with supportive stroma, reorganization of the cytoskeleton system, regulation of cell division, and maintenance of genetic stability represent the most essential steps.