Tissue factor pathway inhibitor can interact with platelets

Tissue factor pathway inhibitor (TFPI) regulates the extrinsic pathway of blood coagulation. However, there is no report on interaction between TFPI and platelets other than that by Tsuji, who found that whole blood anticoagulated with TFPI exhibited remarkable decrease in platelet count. Our study revealed that washed platelets suspended in modified Tyrode's buffer (8 mM CaCl2) containing TFPI exhibit platelet aggregation. However, platelets aggregation was observed without TFPI, but its increase and intensity were slow and weak, compared to that in the presence of TFPI. This aggregation was inhibited by anti-CD41 (anti-GPIIb) antibody. This finding suggested that TFPI promotes platelet aggregation.     

Malignant peripheral nerve sheath tumor of small round cell type with pleomorphic spindle cell sarcomatous areas

An unusual case of malignant peripheral nerve sheath tumor (MPNST) arising in the posterior mediastinum of a 59-year-old man is reported. Histopathologically, the tumor showed an admixture of a dense proliferation of small round cells resembling a primitive neuroectodermal tumor (PNET) and a pleomorphic spindle cell sarcomatous area. Abortive rosettes, primitive neural tube-like structures, and a few glandular structures were found in the small round cell area. Small round cells were immunoreactive for neural cell adhesion molecule and synaptophysin, but were not immunoreactive for MIC2 and neuron-specific enolase. Pleomorphic spindle cells were occasionally arranged in a storiform pattern and were diffusely immunoreactive for S-100 protein. The MPNST of small round cell type is distinguishable from PNET by its negative immunoreactivity for MIC2, and the present tumor is assumed to be derived from primitive neuroectodermal cells in the peripheral nerve capable of bidirectional (neuron and Schwann cell) differentiation.     

The Serum Factor from Patients with Ulcerative Colitis that Induces T Cell Proliferation in the Mouse Thymus Is Interleukin-7

The disturbance of immune regulatory T cells is related to the pathogenesis of ulcerative colitis. Here we demonstrated and characterized the serum factor from ulcerative colitis patients that induced proliferation of intrathymic T cells. The factor isolated from the patient sera by a combination of gel filtration and anion-exchange chromatography induced proliferation of CD4⁺CD8^– intrathymic T cells in the organ-cultured embryonic mouse thymus. Purification and amino acid sequence analysis of the serum factor demonstrated that the N-terminal 12 sequence was homologous to that of interleukin-7. SDS-PAGE and Western blot confirmed that purified serum factor was interleukin-7. Enzyme immunoassay demonstrated that the serum interleukin-7 concentration was significantly increased in the patients. PCR and Southern blot hybridization demonstrated that interleukin-7 mRNA expression was increased in the thymus tissues from patients but decreased in the colonic mucosa. Since interleukin-7 is a crucial cytokine for proliferation and differentiation of T cells in the thymus, the present study indicates that interleukin-7 may contribute to the disturbance of immune regulatory T cells in ulcerative colitis.     

Isolation and mapping of a polymorphic CA repeat sequence at the human VRK1 locus

VRK1 is a novel human putative serine/threonine kinase, and is located on chromosome 14 at band q32 where an autosomal recessive congenital microphthalmia (CMIC) is mapped. We isolated a polymorphic dinucleotide CA repeat marker from a genomic clone containing the human VRK1 gene. This polymorphism will be useful in genetic studies of disorders localized at the 14q32 region, such as CMIC. Received: October 8, 1998 / Accepted: October 16, 1998     

Histopathologic study of partial hydatidiform moles and DNA triploid placentas

Sixty-two placentas with a triploid DNA content, which were analyzed by flow cytometry using paraffin-embedded tissues, were histologically investigated. These placentas were histologically classified as follows: 51 partial hydatidiform moles (PM), two hydropic abortuses and nine non-hydropic placentas. The DNA indices of the triploid peaks were between 1.41 and 1.60. Histologically, two populations of normal and edematous villi, vesicular villous edema with cistern formation, focal syncytiotrophoblastic hyperplasia with vacuola-tion, and villous scalloping with trophoblastic inclusion were almost always observed in the PM, but no single pathologic feature was specific for PM. The two entities, PM and triploid placenta, overlapped. Not all triploid gestations are PM and not all PM moles are triploid as shown in previously reported diploid or tetraploid PM. Although no patient with triploid PM developed persistent disease in this series, follow up of triploid PM is required as long as its true biological potential remains unclear. Flow cytometry is a reliable aid in the diagnosis of PM.     

Activation of natural killer T cells by alpha-galactosylceramide impairs DNA vaccine-induced protective immunity against Trypanosoma cruzi

Innate immunity as a first defense is indispensable for host survival against infectious agents. We examined the roles of natural killer (NK) T cells in defense against Trypanosoma cruzi infection. The T. cruzi parasitemia and survival of CD1d-deficient mice exhibited no differences compared to wild-type littermates. NK T-cell activation induced by administering alpha-galactosylceramide (alpha-GalCer) to T. cruzi-infected mice significantly changed the parasitemia only in the late phase of infection and slightly improved survival when mice were infected intraperitoneally. The combined usage of alpha-GalCer and benznidazole, a commercially available drug for Chagas' disease, did not enhance the therapeutic efficacy of benznidazole. These results suggest that NK T cells do not play a pivotal role in resistance to T. cruzi infection. In addition, we found that the coadministration of alpha-GalCer with DNA vaccine impaired the induction of epitope-specific CD8(+) T cells and undermined the DNA vaccine-induced protective immunity against T. cruzi. Our results, in contrast to previous reports demonstrating the protective roles of NK T cells against other infectious agents, suggest that these cells might even exhibit adverse effects on vaccine-mediated protective immunity.     

Palisading subcutaneous fibrous histiocytoma

A case of palisading subcutaneous fibrous histiocytoma, a very rare variant of fibrous histiocytoma (dermatofibroma), arising in the wrist of a 41-year-old man is presented. An unencapsulated subcutaneous tumor measuring 0.8 x 0.8 x 0.7 cm was histologically characterized by predominant nuclear palisading and a peripheral area with a pattern quite characteristic of conventional fibrous histiocytoma. Immunohistochemically, the tumor cells were strongly positive for vimentin, alpha-smooth muscle, and muscle actin, but negative for S-100 protein, indicating a fibroblastic or myofibroblastic nature. The patient has been well without recurrence for 6 years and 8 months after the excision. This neoplasm should be differentiated from benign and malignant skin or soft tissue tumors with a palisading pattern. Pathologists and clinicians should know of the existence of this type of fibrous histiocytoma and should avoid overdiagnosis and overtreatment.     

Immunohistochemical characterization of p57(KIP2) expression in early hydatidiform moles

The differentiation of complete mole (CM), an aberrant androgenetic conceptus, from partial mole (PM) and hydropic abortion (HA) in early gestations is very important for patient management. In this study, 10 diploid voluntary artificial abortions (ABs), 20 diploid HAs, 20 triploid PMs, and 44 diploid CMs (including 4 persistent diseases), all of which were in the first trimester, were evaluated by immunohistochemistry of formalin-fixed tissues using a monoclonal antibody against p57(KIP2) protein (p57), a putative paternally imprinted inhibitor gene. DNA ploidy in all cases was analyzed by flow cytometry. In all ABs, nuclear p57 was strongly expressed in cytotrophoblasts, intermediate trophoblasts, villous stromal cells, and decidual stromal cells but was absent in syncytiotrophoblast. In diploid CMs, p57 expression in cytotrophoblasts and villous stromal cells was either absent (37 cases) or very low (7 cases). Villous intermediate trophoblasts stained for p57 in 12 cases of CM. On the other hand, 16 HAs and 19 PMs showed p57 levels comparable to those observed in ABs. Decidual stromal cells provided a reliable internal control in all cases. These findings support the hypothesis that misexpression of p57 is involved in the abnormal development of androgenetic CMs. This immunohistochemical analysis is a useful tool for the differential diagnosis of CMs.     

Molecular targeting for epidermal growth factor receptor expressed on breast cancer cells by human fusion protein

Recombinant human ribonuclease 1 (RNasel) was chemically linked to recombinant human epidermal growth factor (EGF). The cytotoxicity of this conjugate was assayed using MTT assay. The EGF-RNase conjugate showed dose-dependent cytotoxicity against breast and squamous cell carcinomas overexpressing the EGF receptor (EGFR). The cytotoxicity of the conjugate correlated positively with the level of EGFR expression by each cell line. These results suggest that the EGF-RNase conjugate is a more effective anticancer agent with less immunogenicity and toxicity than conventional chimeric breast cancer toxins.     

Preparation and Characterization of Dextran Magnetite-Incorporated Thermosensitive Liposomes: An on-line Flow System for Quantifying Magnetic Responsiveness

Purpose. Dextran magnetite (DM)-incorporated thermosensitive liposomes, namely thermosensitive magnetoliposomes (TMs), were prepared and characterized in order to investigate their possibility for magnetic drug targeting. Methods. TMs containing calcein were prepared at various DM concentrations by reverse-phase evaporation of dipalmitoylphosphatidylcholine (DPPC). They were evaluated for their physicochemical properties including size, DM capture, magnetite distribution within liposomes, and temperature-dependent calcein release. Moreover, a novel on-line flow apparatus with a sample injector, a coil of tubing placed in an electromagnet, and a fluorescence detector was developed for quantifying the magnetic responsiveness of TMs. This device allowed us a real-time measurement of percentage holding of TMs by magnetic field. Results. Due to water-soluble property of DM, higher contents of magnetite up to 490 mg per mmol DPPC were successfully incorporated into the liposomes with DM than with conventional magnetite (Fe₃O₄). Thermosensitivity and lipid integrity of TMs were not influenced by inclusion of DM. Using the on-line flow system, percentage holding of TMs by magnetic field was shown to vary with several factors; it increases as the magnetic field strength increases, the fluid flow rate decreases, the magnetite content increases, and the liposome concentration increases. Typically, at 490 mg incorporated magnetite per mmol DPPC, 0.5 ml/min-fluid flow rate, and high magnetic field strength (10 kiloGauss), approximately 100% of TMs were found to be held. Conclusions. The TMs were suggested to be useful in future cancer treatment by magnetic targeting combined with drug release in response to hyperthermia.