Overgrowth and DNA synthesis of neuroepithelium in embryonic stages of induced Long-Evans rat myeloschisis

Overgrowth of the myeloschisis, namely the excessive amount of the neural plate tissue, has been reported in the human myeloschisis. However, it is still debatable how the overgrowth develops and whether the overgrowth is the cause, or the secondary effect of spinal dysraphism. The author induced myeloschisis in the fetuses of Long-Evans rats by the administration of ethylenethiourea (ETU) to pregnant rats on day 10 of gestation. The fetuses were removed 1 hour after the treatment with bromodeoxyuridine (BrdU) to the dams on day 14 and 21. The fetuses were fixed in alcohol and embedded in paraffin. H-E staining and the immunohistologic examination were performed on the staining patterns to anti-neurofilament (NFP), anti-glial fibrillary acidic protein (GFAP) and anti-BrdU antibody by ABC method. On day 14, the lateral portion of everted neural plate showed a loose arrangement of cells and there was rosette formation in the mesoderm. On day 21, cell necrosis was observed at the dorsolateral portion of myeloschisis, although the ventral portion showed almost normal cytoarchitecture and was positive to NFP and GFAP. The cause of myeloschisis in this model is supposed to be the local and direct cytotoxic effect of ETU to neuro-ectodermal junction. On day 14, control animals contained few BrdU-incorporated cells at the basal plate of neural tube. In contrast, everted neural plate showed an active uptake of BrdU diffusely in the subependymal matrix layer cells. Overgrowth was not yet identified. On day 21, overgrowth of myeloschisis was found in spite of a few positive cells to BrdU which was identical to the control animals. These findings seem to suggest that cells in the myeloschisis retain their ability of DNA synthesis for longer periods of development and overgrowth found on day 21 is possibly a secondary effect of spinal dysraphism in this model.     

A rapid dot-blot method for species identification of bloodstains

A very simple and rapid test for species identification is reported. Extracts of bloodstains were applied to a synthetic porous membrane and dried. The membrane was then quenched with glycine buffered saline containing BSA and Tween 20. A suspension of colloidal gold particles (GP) coated with rabbit antiserum to human IgG was poured onto, gently whirled and aspirated through the membrane. Spots from the human and monkey bloodstains became red, whereas those from other species of animals remained unstained. This test was completed within 3 to 4 min, and the antibody-coated GP reagent was prepared within 20 min using a very small quantity of antiserum. Cellulose acetate membranes of 0.45 microns or more in pore size were appropriate to this test.     

Inhibition of G1 cyclin-dependent kinase activity during growth arrest of human breast carcinoma cells by prostaglandin A2

Prostaglandin A2 (PGA2) potently inhibits cell proliferation and suppresses tumor growth in vivo, but little is known regarding the molecular mechanisms mediating these effects. Here we demonstrate that treatment of breast carcinoma MCF-7 cells with PGA2 leads to G1 arrest associated with a dramatic decrease in the levels of cyclin D1 and cyclin-dependent kinase 4 (cdk4) and accompanied by an increase in the expression of p21. We further show that these effects occur independent of cellular p53 status. The decline in cyclin D and cdk4 protein levels is correlated with loss in cdk4 kinase activity, cdk2 activity is also significantly inhibited in PGA2-treated cells, an effect closely associated with the upregulation of p21. Immunoprecipitation experiments verified that p21 was indeed complexed with cdk2 in PGA2-treated cells. Additional experiments with synchronized MCF-7 cultures stimulated with serum revealed that treatment with PGA2 prevents the progression of cells from G1 to S. Accordingly, the kinase activity associated with cdk4, cyclin E, and cdk2 immunocomplexes, which normally increases following serum addition, was unchanged in PGA2-treated cells. Furthermore, the retinoblastoma protein (Rb), a substrate of cdk4 and cdk2 whose phosphorylation is necessary for cell cycle progression, remains underphosphorylated in PGA2-treated serum-stimulated cells. These findings indicate that PGA2 exerts its growth-inhibitory effects through modulation of the expression and/or activity of several key G1 regulatory proteins. Our results highlight the chemotherapeutic potential of PGA2, particularly for suppressing growth of tumors lacking p53 function.     

c-KIT expression enhances the leukemogenic potential of 32D cells

The growth of human leukemic cells in culture and in vivo is dependent upon the presence of hematopoietic growth factors. Most populations of human leukemic acute myeloblastic leukemia (AML) cells express c-Kit on their surface and respond to Kit ligand (KL) in culture. To determine if this interaction was of potential significance in vivo we used a mouse model system. 32D cells, a murine IL-3-dependent myeloid cell line, were rendered KL responsive by transfection of the murine c-Kit. After injection of 32D or 32D-Kit cells into syngeneic hosts, animals bearing 32D-Kit cells, but not 32D cells, became moribund and were killed. These animals had circulating leukemic blast cells, infiltration of bone marrow, spleen, brain, liver, lung, and kidney. Cells recovered from some of the animals continued to be dependent upon IL-3 or KL for growth while in other cases the cells were factor independent. This model illustrates that the constitutive expression of c-Kit enhances the leukemic potential of 32D cells. The model will be useful for studying the progression of leukemia in vivo and testing whether interruption of the interaction of Kit and KL can affect the growth of leukemic cells.     

Successful surgical repair for a patient with atrial septal defect and severe pulmonary hypertension--its surgical indication and prostaglandin E1 use for postoperative pulmonary hypertensive crisis

A 45-year-old woman with atrial septal defect and pulmonary hypertension was admitted for surgical repair. Cardiac catheterization data revealed pulmonary to systemic flow ratio (Qp/Qs) of 1.81, pulmonary artery pressure (PAP) of 82/30 mmHg and pulmonary vascular resistance (PVR) of 10.8 unit. Open lung biopsy was added to evaluate pulmonary vascular obstructive disease (PVOD) which was shown Heath-Edwards grade 3 PVOD. Following closure of the defect, PAP (systolic) exceeded momentarily systemic level after cardiopulmonary bypass. Prostaglandin E1 drip was remarkably effective to bring down PAP during early postoperative period. Although PAP has not been shown significant decrease on catheterization of one year after surgery, great symptomatic improvement has been achieved.     

Idiopathic epilepsy in the dog

The authors present a brief history of the development of the Ilizarov external fixator, and the classic uses associated with it. A preliminary study of 3 patients using 56 frames is presented. The Ilizarov external fixator is successfully used in these cases in place of traditional fixation.     

Dynamic programming implementation on array processor architectures

Dynamic Programming (DP) applies to many signal and image processing applications including boundary following, the Viterbi algorithm, dynamic time warping, etc. This paper presents an array processor implementation of generic dynamic programming. Our architecture is a SIMD array attached to a host computer. The processing element of the architecture is based on an ASIC design opting for maximum speed-up. By adopting a torus interconnection network, a dual buffer structure, and a multilevel pipeline, the performance of the DP chip is expected to reach the order of several GOPS. The paper discusses both the dedicated hardware design and the data flow control of the DP chip and the total array.This work was supported in part by the NATO, Scientific and Environmental Affairs Division, Collaborative Research Grant SA.5-2-05(CRG.960201)424/96/JARC-501.     

A neural network-based power system stabilizer using power flowcharacteristics

A neural network-based power system stabilizer (neuro-PSS) is designed for a generator connected to a multi-machine power system utilizing the nonlinear power flow dynamics. The use of power flow dynamics provides a PSS for a wide range of operation with reduced size neural networks. The neuro-PSS consists of two neural networks: neuro-identifier and neuro-controller. The low-frequency oscillation is modeled by the neuro-identifier using the power flow dynamics, then a generalized backpropagation-through-time (GBTT) algorithm is developed to train the neuro-controller. The simulation results show that the neuro-PSS designed in this paper performs well with good damping in a wide operation range compared with the conventional PSS