Effects of temperature on granulocyte preservation

With the increasing use of granulocyte transfusion it is becoming important to determine if granulocytes can be preserved for a few days. If so, the optimum storage conditions must be identified. We studied the function in vitro of granulocytes collected as they would be for transfusion by continuous-flow centrifuge leukapheresis (CFCL) and filtration leukapheresis (FL). Granulocytes collected by CFCL maintained normal ability to phagocytose and kill bacteria after 48 hr and normal chemotaxis after 24 hr of storage at 20 degrees--24 degrees C. Neither 1 degrees--6 degrees C nor 37 degrees C were as effective in preserving chemotactic response. Agitation of the granulocyte suspension during storage caused reduced bacterial killing and chemotaxis. Granulocytes collected by FL functioned very poorly after 24 hr storage at all temperatures studied. These studies suggest that it may be possible to store CFCL granulocytes at 20 degrees--24 degrees C for 24 hr. FL granulocytes should not be stored at all.     

Phenotypic heterogeneity of spontaneous lymphomas of CWD mice

Animals of the inbred mouse strain, CWD, express endogenous murine leukemia viruses early in life and have a high incidence of spontaneous neoplasms. We found that approximately one half of these animals died of malignant lymphoma by the age of 16 months. Splenic enlargement was seen in all mice, but thymic involvement was unusual. One half of the CWD tumors were diffuse lymphoblastic or immunoblastic lymphomas while the remainder were large cell, small cell, or mixed cell lymphomas. Analysis of DNAs from 12 tumors for immunoglobulin and T-cell receptor gene rearrangements revealed that all six of the lymphoblastic and immunoblastic lymphomas were of T-cell origin, as was one tumor of small cleaved cells. Four of the others were clonal B-cell lymphomas and one was of uncertain lineage. Assays of a limited number of tumors for the expression of the Thy 1.2 and IgM molecules confirmed the diversity in the cellular phenotype. The results indicate that CWD mice develop primarily splenic lymphomas with an unusual degree of heterogeneity in the tumor cell phenotypes as compared with the thymic lymphomas found in other high leukemia strains. The CWD strain is a useful new model for studies of retroviral leukemogenesis and the relationship between the histopathology and immunophenotype of malignant lymphomas.     

Point mutations in the conserved box 1 region inactivate the human granulocyte colony-stimulating factor receptor for growth signal transduction and tyrosine phosphorylation of p75c-rel

The human granulocyte colony-stimulating factor receptor (hG-CSFR) belongs to the cytokine receptor superfamily. As with other members of this family, the cytoplasmic domain of hG-CSFR lacks intrinsic tyrosine kinase activity. To identify critical regions mediating growth signal transduction by hG-CSFR, deletions or site-directed amino acid substitutions were introduced into the cytoplasmic domain of hG-CSFR, and the mutant cDNAs were transfected into the murine interleukin-3 (IL- 3)-dependent Ba/F3 and FDCP cell lines. Truncation of the carboxy- terminal end of the receptor to the membrane-proximal 53 amino acids of the cytoplasmic domain, which retained the conserved Box 1 and Box 2 sequence motifs, decreased the ability of hG-CSFR to transduce G-CSF- mediated growth signals without an associated loss in receptor binding affinity. Substitution of proline by alanine at amino acid positions 639 and 641 within Box 1 completely abolished the G-CSF-mediated growth signal. Rapid induction of tyrosine phosphorylation of several cellular proteins, including a 75-kD protein (p75) identified as c-rel, was an early event associated with transduction of proliferative signals by hG- CSFR in Ba/F3 transfectants. Mutant receptors containing Pro-to-Ala substitutions that inactivated the receptor for mitogenic activity also inactivated the receptor for tyrosine-specific phosphorylation of p75. These results show that the conserved Box 1 sequence motif (amino acids 634 to 641) is critical for mitogenesis and activation of cellular tyrosine kinases by hG-CSFR.     

Receptor specificity of clinical Plasmodium falciparum isolates: nonadherence to cell-bound E-selectin and vascular cell adhesion molecule-1

The pathogenicity of Plasmodium falciparum is due largely to the parasite's unique ability to adhere to capillary and postcapillary venular endothelium during the second-half of the 48-hour life cycle. The resulting sequestration of infected erythrocytes (IRBC) in deep vascular beds leads to tissue hypoxia, metabolic disturbances, and organ dysfunction which characterize severe falciparum malaria. Several endothelial receptors of cytoadherence have been identified, but their clinical relevance remains controversial. In the present report, the receptor specificity of 60 clinical P falciparum isolates was determined using transfectants each expressing one of CD36, intercellular adhesion molecule-1 (ICAM-1), E-selectin, and vascular cell adhesion molecule-1 (VCAM-1). All isolates tested adhered to CD36 and ICAM-1, but the adherence to CD36 was at least 10-fold higher. Seven isolates adhered to E-selectin whereas none of 19 isolates adhered to VCAM-1. From a population standpoint, about 30% of IRBC in each isolate adhered to CD36, and 2% to 3% adhered to ICAM-1. The percentage adherent to E-selectin and VCAM-1 was negligible. IRBC selected on CD36 adhered almost exclusively to CD36 whereas 80% to 90% of IRBC selected on ICAM-1 could also adhere to CD36. Selected IRBC did not adhere to E-selectin or VCAM-1. These findings indicate that cytoadherence to multiple endothelial receptors is a rare occurrence with natural P falciparum isolates, but do not exclude a role for the adhesion molecules in promoting other IRBC-endothelial interactions such as rolling under flow conditions. Receptor specificity in vivo may be dictated by the ligand-receptor combination which provides the best survival potential for the parasite.     

Shear-dependent changes in the three-dimensional structure of human von Willebrand factor

The three-dimensional tertiary structure of human von Willebrand Factor (vWF) on a hydrophobic surface under aqueous conditions and different shear stress regimes was studied by atomic force microscopy (AFM). vWF was imaged by AFM at molecular level resolution under negligible shear stress, under a local applied shear force (7.4 to 19 nN) using the AFM probe in contact mode scanning, and after subjecting vWF to a range of shear stress (0 to 42.4 dyn/cm2) using a rotating disk system. The results demonstrate that vWF undergoes a shear stress-induced conformational transition from a globular state to an extended chain conformation with exposure of intra-molecular globular domains at a critical shear stress of 35 +/- 3.5 dyn/cm2. The globular vWF conformation (149 nm by 77 nm and height 3.8 nm) is representative of native vWF after simple diffusion to the hydrophobic surface, followed by adhesion and some spreading. In a shear stress field above the critical value, protein unfolding occurs and vWF is observed in extended chain conformations oriented in the direction of the shear stress field with molecular lengths ranging from 146 to 774 nm and 3.4 nm mean height. The shear stress-induced structural changes to vWF suggest a close conformation-function relationship in vWF properties for thrombogenesis in regions of high shear stress.     

Characterization of 25 monoclonal antibodies to factor VIII-von Willebrand factor: relationship between ristocetin-induced platelet aggregation and platelet adherence to subendothelium

We have studied the role of factor VIII-von Willebrand factor (FVIII- vWF) in both platelet adherence to subendothelium and ristocetin- induced platelet aggregation using monoclonal antibodies to human FVIII- vWF. Twenty-five monoclonal antibodies were obtained, two of which were directed to the factor VIII moiety of FVIII-vWF; one of these two completely inhibited the procoagulant activity (FVIII:C). The remaining 23 monoclonal antibodies were directed to the von Willebrand factor moiety of FVIII-vWF. The ability of the latter monoclonal antibodies to inhibit platelet adherence to arterial subendothelium was investigated with a perfusion model. According to the number of platelets adhering to the subendothelium, three groups of monoclonal antibodies could be discerned: (A) antibodies not affecting platelet adherence; (B) antibodies that inhibited platelet adherence to the level as observed when von Willebrand's disease plasma was tested; and (C) antibodies that completely inhibited both platelet adherence to subendothelium and ristocetin-induced platelet aggregation. The two antibodies present in group C competed for the same or closely related epitope(s) present on FVIII-vWF. These results demonstrate that a domain is present on the FVIII-vWF molecule that is associated both with ristocetin-induced aggregation and with the ability of FVIII-vWF to support platelet adherence to the subendothelium. Based on these observations, it is concluded that ristocetin-induced binding of FVIII-vWF to platelets reflects, at least in part, a physiologic mechanism regulating the function of FVIII-vWF in primary hemostasis.     

Serological confirmation of human T-lymphotropic virus type I infection in healthy blood and plasma donors

We wished to develop criteria for serological confirmation of human T- lymphotropic virus type I (HTLV-I) infection in healthy donors. Selected serum or plasma samples reactive by HTLV-I enzyme immunosorbent assay or gel-agglutination assays with at least one viral- specific band on Western immunoblot (WIB) were tested in six laboratories by four WIBs and four radioimmunoprecipitation assays (RIPAs) for antibodies to HTLV-I proteins encoded by gag (p19 and p24), env (gp46 and/or gp61), and tax (p40x) genes. One hundred forty-two donor sera were obtained from 38 Japanese, 69 American, and 35 Caribbean blood or plasma donors. Among these samples, WIB assays appeared more sensitive to p24 antibodies, whereas RIPAs were significantly more sensitive to gp61 antibodies. All sera (137) with gp61 antibodies had p24 antibodies. Of the 137 sera positive for p24 and gp61 antibodies, p19 antibodies were detected in 129 sera, and p40x antibodies were detected in 108. In sera with p19 antibodies and antibodies to env- or tax-encoded proteins, p24 antibodies were always present. Antibodies to p40x were not found in the absence of gp61 antibodies. Virological evidence of infection was found in seven American donors by lymphocyte coculture (one HTLV-I, one HTLV-II) or by polymerase chain reaction (three HTLV-I, two HTLV-II). Sera from all seven donors showed p24 and gp46 and/or gp61 antibodies. We suggest that seroreactivity to both p24 and gp46 and/or gp61 by WIB or RIPA or both are suitable criteria to confirm but not to distinguish HTLV-I and HTLV-II infections.     

Abnormal erythroid progenitor cells in human preleukemia

Ten patients with preleukemia were studied by the erythroid cell clonal culture technique. In nine of these patients, erythroid colonies derived from peripheral blood BFU-E were not observed, while the other patient had markedly decreased peripheral blood BFU-E-derived erythroid colonies in vitro. In three patients, marrow cells were also cultured and no BFU-E-derived erythroid colonies were detected. These studies indicate that immature erythroid progenitor cells, BFU-E, in patients with preleukemia are either markedly decreased in number or grossly defective in their proliferative or differentiative capacities.     

大环骨架结构的倍半萜化合物——Ⅵ.马兜铃新内酯的化学结构测定

自绵毛马兜铃(Aristolochia mollissima Hance)根茎中分得九个化合物,其中已报道的七个化合物是尿囊素、马兜铃内酯、绵毛马兜铃内酯、β-谷甾醇、马兜铃酸A、9-乙氧基马兜铃内酯和9-乙氧基马兜铃内酰胺,本文报道结晶K₃的化学结构,经光谱分析(IR,¹H-NMR,¹³C-NMR,2D-NMR和MS),化学反应及X-衍射晶体分析,确证K₃为一个新骨架结构的倍半萜化合物,命名为马兜铃新内酯。