Splenic extramedullary hematopoietic proliferation in Philadelphia chromosome-negative myeloproliferative neoplasms: heterogeneous morphology and cytological composition.

We studied 24 spleens with extramedullary hematopoietic proliferation (EMHP), a key feature of advanced-stage Philadelphia chromosome-negative myeloproliferative neoplasms, obtained from 24 patients (14 primary myelofibrosis, 7 polycythemia vera and 3 unclassifiable). Hematoxylin and eosin, reticulin and trichrome stains, and immunohistochemical stains for myeloperoxidase, glycophorin-C, CD42b, CD34, CD117, CD8, nerve growth factor receptor and smooth muscle actin were evaluated. Clinical information was correlated with the morphological findings. Three distinct histological patterns of EMHP were recognized: diffuse (12), nodular (5), and mixed-nodular and diffuse (7). The preponderant lineage was granulocytic in diffuse, trilineage in nodular and erythroid in mixed EMHP. Erythropoiesis was largely intravascular, granulopoiesis was within the splenic cords and megakaryopoiesis was observed in both locations. The stromal changes paralleled the histological pattern with preservation of the splenic stromal and vascular architecture in the diffuse areas as opposed to areas of nodular EMHP. The morphological features of the splenic EMHP did not correlate with specific subtypes of myeloproliferative neoplasms. The mean duration of follow-up from initial diagnosis was 80 months. A total of 15 of the 24 patients died of disease: 8 of 12 (67%) with diffuse, 2 of 5 (40%) with nodular and 5 of 7 (71%) with mixed growth patterns. The mean duration from diagnosis to splenectomy was shorter in patients with diffuse (83 months) as compared with those with nodular EMHP (127 months). Our study demonstrates that splenic extramedullary hematopoietic proliferation in Philadelphia chromosome-negative myeloproliferative neoplasms shows distinct histological patterns that do not correlate with disease subtypes, but appear to suggest a trend between the histological patterns and clinical behavior. These results suggest a different biology of the disease in the nodular and diffuse extramedullary hematopoietic proliferation groups.

A20 (TNFAIP3) genetic alterations in EBV-associated AIDS-related lymphoma.

A20, a negative regulator of NF-κB, has been implicated as a tumor suppressor gene in multiple types of B-cell lymphoma. AIDS-related lymphomas (ARLs) are high-grade B-cell lymphomas that are frequently associated with EBV infection. We examined a panel of ARLs for A20 alterations. FISH showed A20 deletion in 6 of 33 cases (18%). A20 mutations were found in 3 of 19 cases (16%), including 2 cases with deletions of the comple-mentary allele. Immunohistochemistry showed the absence of A20 protein in 7 of 55 samples (13%). In contrast to reports in Hodgkin lymphoma in which EBV infection and A20 alteration are mutually exclusive, A20 inactivation was observed in both EBV(+) and EBV(-) cases. The EBV latent membrane protein 1, which activates NF-κB, was not expressed in 12 of 13 cases with A20 loss. In ARLs loss of A20 may be an alternative mechanism of NF-κB activation in the absence of latent membrane protein 1 expression.

17ß-estradiol increases astrocytic vascular endothelial growth factor (VEGF) in adult female rat hippocampus.

Vascular endothelial growth factor (VEGF) is critical to angiogenesis and vascular permeability. It is also important in the endocrine system, in which VEGF mediates the vascular effects of estrogens in target tissues such as the uterus, a response attributed to an estrogen response element on the VEGF gene. Here we asked whether 17ß-estradiol increases VEGF levels in the brain. We focused on the hippocampus, in which 17ß-estradiol and VEGF both have important actions, and used immunocytochemistry to evaluate VEGF protein. VEGF immunoreactivity was compared in adult female rats sampled during the estrous cycle when serum levels of 17ß-estradiol peak (proestrous morning) as well as when they are low (metestrous morning). In addition, adult rats were ovariectomized and compared after treatment with 17ß-estradiol or vehicle. The results demonstrated that VEGF immunoreactivity was increased when serum levels of 17ß-estradiol were elevated. Confocal microscopy showed that VEGF immunofluorescence was predominantly nonneuronal, often associated with astrocytes. Glial VEGF labeling was primarily punctate rather than diffuse and labile because glial VEGF immunoreactivity was greatly reduced if tissue sections were left in an aqueous medium overnight. We conclude that VEGF protein in normal female hippocampus is primarily nonneuronal rather than neuronal and suggest that glial VEGF immunoreactivity has been underestimated by past studies with other methods because there is a labile extracellular pool. We suggest that estrogens may exert actions on female hippocampal structure and function by increasing hippocampal VEGF.

Changes in hippocampal function of ovariectomized rats after sequential low doses of estradiol to simulate the preovulatory estrogen surge.

In adult female rats, robust hippocampal changes occur when estradiol rises on the morning of proestrus. Whether estradiol mediates these changes, however, remains unknown. To address this issue, we used sequential injections of estradiol to simulate two key components of the preovulatory surge: the rapid rise in estradiol on proestrous morning, and the slower rise during the preceding day, diestrus 2. Animals were examined mid-morning of simulated proestrus, and compared to vehicle-treated or intact rats. In both simulated and intact rats, CA1-evoked responses were potentiated in hippocampal slices, and presynaptic mechanisms appeared to contribute. In CA3, multiple population spikes were evoked in response to mossy fiber stimuli, and expression of brain-derived neurotrophic factor was increased. Simulation of proestrous morning also improved performance on object and place recognition tests, in comparison to vehicle treatment. Surprisingly, effects on CA1-evoked responses showed a dependence on estradiol during simulated diestrus 2, as well as a dependence on proestrous morning. Increasing estradiol above the physiological range on proestrous morning paradoxically decreased evoked responses in CA1. However, CA3 pyramidal cell activity increased further, and became synchronized. Together, the results confirm that physiological estradiol levels are sufficient to profoundly affect hippocampal function. In addition: (i) changes on proestrous morning appear to depend on slow increases in estradiol during the preceding day; (ii) effects are extremely sensitive to the peak serum level on proestrous morning; and (iii) there are striking subfield differences within the hippocampus.