Location of the complement factor H binding site on streptococcal M6 protein

The surface M protein of group A streptococci binds factor H, a regulatory protein of the alternative complement pathway, which may contribute to the antiphagocytic activity of the M molecules. To locate the factor H binding domain in the alpha-helical coiled-coil structure of the M molecule, the M protein was cleaved with pepsin at pH 5.8, which separates the molecule approximately in half. Western blot (immunoblot), amino acid sequence, and mass spectrometric analyses revealed that factor H bound to a 14.6-kDa C-terminal fragment of the M molecule. Competitive inhibition of factor H binding to the 14.6-kDa fragment with M protein peptides localized the binding site to amino acids 256 to 292. This segment is located within the surface-exposed region of the M6 protein, identified as the C-repeat region, whose sequence is conserved among heterologous M and M-like molecules. These studies also identified a second pepsin-susceptible site with the sequence ELAK located within the cell wall-associated region of the M molecule.     

Replacement of tyrosine 1251 in the carboxyl terminus of the insulin-like growth factor-I receptor disrupts the actin cytoskeleton and inhibits proliferation and anchorage-independent growth

Insulin-like growth factor (IGF)-I signaling through the IGF-I receptor modulates cellular adhesion and proliferation and the transforming ability of cells overexpressing the IGF-I receptor. Tyrosine phosphorylation of intracellular proteins is essential for this transduction of the IGF-I-induced mitogenic and tumorigenic signals. IGF-I induces specific cytoskeletal structure and the phosphorylation of proteins in the associated focal adhesion complexes. The determination of the exact pathways emanating from the IGF-I receptor that are involved in mediating these signals will contribute greatly to the understanding of IGF-I action. We have previously shown that replacement of tyrosine residues 1250 and 1251 in the carboxyl terminus of the IGF-I receptor abrogates IGF-I-induced cellular proliferation and tumor formation in nude mice. In this study, replacement of either tyrosine 1250 or 1251 similarly reduces the cells ability to grow in an anchorage-independent manner. The actin cytoskeleton and cellular localization of vinculin are disrupted by replacement of tyrosine 1251. Tyrosine residues 1250 and 1251 are not essential for tyrosine phosphorylation of two known substrates; insulin receptor substrate-1 and SHC, nor association of known downstream adaptor proteins to these substrates. In addition, these mutant IGF-I receptors do not affect IGF-I-stimulated p42/p44 mitogen-activated protein kinase activation or phosphatidylinositol (PI) 3'-kinase activity. Thus, it appears that in fibroblasts expressing tyrosine 1250 and 1251 mutant IGF-I receptors, the signal transduction pathways impacting on mitogenesis and tumorigenesis do not occur exclusively through the PI 3'-kinase or mitogen-activated protein kinase pathways.     

Caffeine and other predictors of bone density among pre- and perimenopausal women

Cryopreservation has proved to be a highly successful method for long-term storage of viable embryos. The objective of this study on rat blastocysts was to define conditions for their cryopreservation. Three cryoprotectants, dimethyl sulfoxide, glycerol, and propanediol/sucrose, were compared in two cooling programs (to -30 or -80 degrees C) and two thawing protocols. The cooling was followed by immersion in liquid nitrogen. Programmed thawing was at the rate of 8 degrees C per minute; fast thawing consisted of direct exposure of the frozen embryos to the ambient laboratory temperature. The survival after the freeze/thaw was assessed from the post-thaw embryo morphology and ability to develop into apparently normal offspring in uteri of foster mothers (embryonic survival). The best method for preservation of rat blastocysts proved to be programmed cooling to -80 degrees C followed by fast thawing with glycerol as cryoprotectant (embryonic survival of 28.1%). In all the experimental groups, the proportion of embryos with good to excellent preservation of morphology was high. With dimethyl sulfoxide, after programmed cooling to -80 degrees C, embryonic survival was 9.9% (programmed thawing) and 17.5% (fast thawing). No embryos survived after programmed cooling to -30 degrees C. However, when the cryoprotectant was propanediol/sucrose, no difference was observed between programmed cooling to -80 degrees C with either method of thawing and programmed cooling to -30 degrees C and fast thawing (12.3, 6.2, and 8.0%, respectively).     

Tumor cell procoagulant and urokinase expression in carcinoma of the ovary

BACKGROUND: An association between cancer and increased blood coagulation has been observed for many years. Generally, there is an equilibrium between the coagulation system (fibrin deposition) and the fibrinolytic system (degradation of fibrin by enzymes). However, in malignant disease such as ovarian carcinoma, this equilibrium is disrupted, resulting in the abnormal activation of coagulation or hypercoagulability. Also, evidence indicates that various components of these pathways may contribute to the disorderly characteristics of malignancy, such as proliferation, invasion, and metastasis. PURPOSE: Our purpose was to define the mode of interaction of tumor cells in ovarian carcinoma with both the coagulation (procoagulant-initiated) and fibrinolysis (urokinase-type plasminogen activator-initiated) (u-PA) pathways. METHODS: Studies were performed on acetone-methylbenzoate-xylene-fixed tissue prepared from fresh resected primary tumor specimens from 15 patients with cystic epithelial ovarian carcinoma. None of the patients had received prior treatment. Antibodies were tested on control and tumor tissues in concentrations that provided maximum staining intensity with minimum background staining. Laboratory immunohistochemical techniques used purified, monospecific antibodies to detect coagulant antigens. Tests were performed utilizing antibodies to recombinant human tissue factor; factor VII; factor X; factor XIIIA; high-molecular-weight and low-molecular-weight forms of u-PA; tissue-type plasminogen activator; plasminogen; and the plasminogen activator inhibitors 1, 2, and 3. Monoclonal antibodies used for specific antigen detection included 1-8C6 (fibrinogen), T2G1 (fibrin), and EBM-11 (macrophage-specific). RESULTS: The ovarian tumor cells expressed urokinase-type plasminogen activator in a pattern that was variable in intensity and distribution. Tumor cell plasminogen was not detected. Tumor cells also expressed tissue factor and coagulation pathway intermediates that resulted in local thrombin generation as evidenced by the conversion of fibrinogen (present in tumor connective tissue) to fibrin that was found to hug the surfaces of tumor nodules and individual tumor cells. Detected fibrin could not be accounted for on the basis of necrosis or a local inflammatory cell infiltrate. CONCLUSIONS: These results are consistent with the existence of a dominant tumor cell-associated procoagulant pathway that leads to thrombin generation and hypercoagulability in carcinoma of the ovary. IMPLICATIONS: In ovarian carcinoma the procoagulant pathway may contribute to tumor progression. Clinical trials of therapeutic drugs capable of limiting local coagulability (anticoagulants, protease inhibitors) are indicated in this tumor type.     

Parameter estimation technique for sensitive elements of microaccelerometers and micromirrors

The results on the application of the research technique developed for measuring micromechanical element parameters are reported. This technique was used in combination with calculation results to determine the parameters of micromirror prototypes.     

Anesthesiological support, postoperative care and the results of the surgical treatment of patients with tumors of the base of the posterior cranial fossa

Problems of anesthesiological maintenance, measures of the postoperative management and results of surgical treatment of 76 patients with an oncological process on the base of the posterior cranial fossa are discussed. An analysis of informative-regulatory and adaptational reactions of organism is made on the basis of the intervalogram in the course of operative interventions near by the cerebral trunk. The results are estimated.     

Chronic nonspecific endometritis

To assess the proliferative activity of glands and stroma in nonspecific chronic endometritis (NCE), we evaluated the plasma and morphologic features. We examined 25 endometrial sections that were coded as inactive for the morphologic features of NCE other than plasma cells and 25 proliferative endometria (PE) as controls. Furthermore, the sections were stained with methyl green pyronin (MGP) to demonstrate plasma cells and proliferative cell nuclear antigen (PCNA) for proliferative activity. The number of plasma cells and the grade of proliferative activity were determined by a semiquantitative scale. The results were compared by using the Mann-Whitney-U-test. Of the 25 inactive endometria cases, 11 were NCE and 14 were either early proliferative endometria (seven cases), lower uterine segments (five cases), or under hormone effect (two cases). The number of plasma cells in NCE was significantly higher than in PE. However, there were cases of NCE without plasma cells and cases of PE containing plasma cells. Proliferative activity was significantly lower in NCE cases than in the PE group (p < 0.05). The diagnosis of NCE should rely more on morphologic abnormalities than on plasma cell criteria. Identification of plasma cells may be useful for diagnosis.