A high-affinity folate binding protein in normal human leukocytes: Ligand binding characteristics,ionic charge and molecular size

High-affinity binding of [³H]folate to supernatant from homogenized human leukocytes containing large amounts of binding protein displayed apparent positive cooperativity. The DEAE-Sepharose^® CL-6B chromatographic profile of the supernatant at pH 6.3 contained a major peak of folate binding (M_r approx. 25 000) in the front effluent and a smaller more acidic peak (M_r approx. 25 000) that emerged after a rise in NaCl from 30 mmol/l to 1 mol/l. Triton X-100 solubilized ceil sediment from the leukocyte homogenate contained some high-affinity folate binding activity (M_r approx 25 000), typically 5–10% of the total binding activity.     

The secretion and action of the digestive enzymes of the salivary glands of the blowfly, Calliphora

The salivary glands of adult Calliphora contain enzymes which hydrolyze starch, sucrose and trehalose. Amylase and sucrase are shown to be secretory enzymes, while trehalase remains in the gland. Results of electrophoretic and ultrastructural studies suggest that protein secretion is confined to the abdominal region of the gland. Secretion of both fluid and protein occurs from a single type of cell. While a fly is feeding on solid sugar, amylase and sucrase are lost from the gland and appear in saliva, while the level of trehalase in the gland increases slightly. The mixture of food and saliva passes mainly to the crop where carbohydrate is digested by the salivary enzymes.     

A reduced model of the fluorescence from the cyanobacterial photosynthetic apparatus designed for the in situ detection of cyanobacteria

Fluorometric determination of the chlorophyll (Chl) content of cyanobacteria is impeded by the unique structure of their photosynthetic apparatus, i.e., the phycobilisomes (PBSs) in the light-harvesting antennae. The problems are caused by the variations in the ratio of the pigment PC to Chl a resulting from adaptation to varying environmental conditions. In order to include cyanobacteria in fluorometric analysis of algae, a simplified energy distribution model describing energy pathways in the cyanobacterial photosynthetic apparatus was conceptualized. Two sets of mathematical equations were derived from this model and tested. Fluorescence of cyanobacteria was measured with a new fluorometer at seven excitation wavelength ranges and at three detection channels (650, 685 and 720 nm) in vivo. By employing a new fit procedure, we were able to correct for variations in the cyanobacterial fluorescence excitation spectra and to account for other phytoplankton signals. The effect of energy-state transitions on the PC fluorescence emission of PBSs was documented. The additional use of the PC fluorescence signal in combination with our recently developed mathematical approach for phytoplankton analysis based on Chl fluorescence spectroscopy allows a more detailed study of cyanobacteria and other phytoplankton in vivo and in situ.     

A scapular coordinate frame for clinical and kinematic analyses

The aim of this study was to define a body-fixed coordinate frame for the scapula that minimises axes variability and is closely related to the clinical frame of reference. Medical images of 21 scapulae were used to quantify 14 different axes from identifiable landmarks. The plane of the blade of the scapula was defined. The orientations of the quantified axes were calculated. The angular relationships between axes were quantified and applied to grade the sensitivity of each axis to inter-scapular variations in the others. The volume of data required to define an axis was noted for its dependency on pathology and the three criteria were weighted according to relative importance. The two axes with the highest weighting were applied to define a body-fixed Cartesian coordinate frame for the scapula. A least square medio-lateral line through the centre of the spine root was the most optimal axis. The plane formed by the spine root line and a least square line through the centre of the lateral border ridge was the most optimal scapular plane. This body-fixed Cartesian coordinate frame is closely aligned to the cardinal planes in the anatomical position and thus is a clinically applicable, specimen invariant coordinate frame that can be used in patient-specific kinematics modelling.     

Macro nutrient cation uptake by plants

Summary In pot experiments with barley, mustard, leek, lettuce and spinach, and in a field experiment with 30 cultivars of barley uptakes of K, Mg, Ca, Na and N were studied at varying concentrations and activities of these cations in the soil solution.The sum of macro cations (K, Mg, Ca, Na) in meq per 100 g aerial plant parts were independent of the chemical composition of the soil solution, but dependent on plant species and on the N concentration in the plant.The ratios of mean net inflows of Mg, Ca and K into plants and corresponding cation activity ratios (a_Mg/a_Ca and ) in the soil solution were linearly related and highly correlated under conditions in which growth rate and/or rate of incorporation into new tissues constituted the rate determining step of cation uptake. Consequently, mean net inflows of K, Mg and Ca were independent of ion concentration and ion activity of K, Mg or Ca in the soil solution under the conditions of constant activity ratio.The results agree with the concept that plants have a finite cation uptake capacity, and that plants are in a equilibrium-like state with the activities of K, Mg, and Ca ions in the soil solution. The results indicate that both ratios and content of exchangeable cations should be considered in our evaluation of soil test data.     

Analysis of cervical smears obtained within three years of the diagnosis of invasive cervical cancer

The cytologic histories of 376 women presenting with invasive carcinoma of the cervix were analyzed. In total, 202 (53.7%) of these women had had 355 smears taken during the three years preceding presentation. All 320 smears with an original cytologic diagnosis of less than cancer were reviewed. The original cytologic diagnosis was low in 95 (30.6%) of 310 adequate smears. Originally, 96 (30.9%) of the adequate smears were evaluated as negative; at review, only 55 (17.5%) of the adequate smears were evaluated as negative. Comparing the review diagnoses to the 355 total smears, the rates of negative smears were 13.5% (42 of 310) for squamous-cell carcinoma, 30.0% (12 of 40) for adenocarcinoma and 20.0% (1 of 5) for adenosquamous carcinoma (P less than .05). The cellular composition of the smear was significantly related to the cytologic detection of abnormalities: endocervical cylindrical and/or metaplastic cells were seen in only 45.5% of smears diagnosed as negative, but in 84.4% and 97.8% of smears diagnosed as atypia and cervical intraepithelial neoplasia, respectively P less than .00001). Smears without endocervical cells should be considered inadequate and should be repeated.     

A Binding Domain on Mesothelin for CA125/MUC16

Ovarian cancer and malignant mesothelioma frequently express both mesothelin and CA125 (also known as MUC16) at high levels on the cell surface. The interaction between mesothelin and CA125 may facilitate the implantation and peritoneal spread of tumors by cell adhesion, whereas the detailed nature of this interaction is still unknown. Here, we used truncated mutagenesis and alanine replacement techniques to identify a binding site on mesothelin for CA125. We examined the molecular interaction by Western blot overlay assays and further quantitatively analyzed by enzyme-linked immunosorbent assay. We also evaluated the binding on cancer cells by flow cytometry. We identified the region (296–359) consisting of 64 amino acids at the N-terminal of cell surface mesothelin as the minimum fragment for complete binding activity to CA125. We found that substitution of tyrosine 318 with an alanine abolished CA125 binding. Replacement of tryptophan 321 and glutamic acid 324 with alanine could partially decrease binding to CA125, whereas mutation of histidine 354 had no effect. These results indicate that a conformation-sensitive structure of the region (296–359) is required and sufficient for the binding of mesothelin to CA125. In addition, we have shown that a single chain monoclonal antibody (SS1) recognizes this CA125-binding domain and blocks the mesothelin-CA125 interaction on cancer cells. The identified CA125-binding domain significantly inhibits cancer cell adhesion and merits evaluation as a new therapeutic agent for preventing or treating peritoneal malignant tumors.Ovarian cancer largely is confined to the peritoneal cavity for much of its natural history (1). Peritoneal mesothelioma is a highly invasive tumor originating from the mesothelial linings of the peritoneum (2). The development of effective drug regimens against ovarian cancer and mesothelioma has proven extremely difficult.Mesothelin was first identified in 1992 by the monoclonal antibody (mAb)² K1 that was generated by the immunization of mice with human ovarian carcinoma (OVCAR-3) cells (3). The mesothelin gene encodes a 71-kDa precursor protein that is processed to a 40-kDa protein termed mesothelin, which is a glycosylphosphatidylinositol (GPI)-anchored glycoprotein present on the cell surface (4). Mesothelin is a differentiation antigen that is present on a restricted set of normal adult tissues such as the mesothelium. In contrast, it is overexpressed in a variety of cancers including mesothelioma, ovarian cancer, and pancreatic cancer (5). In addition, mesothelin is also expressed on the surface of non-small cell lung cancer cells (6, 7), especially most lung adenocarcinomas (8).We and others have shown that mesothelin is shed from tumor cells (9, 10), and antibodies specific for mesothelin are elevated in the sera of patients with mesothelioma and ovarian cancer (11). Shed serum mesothelin has been approved by the United States Food and Drug Administration (FDA) as a new diagnostic biomarker in mesothelioma. In a Phase I clinical study of an intrapleural interferon-β gene transfer using an adenoviral vector in patients with mesotheliomas, we found that antitumor immune responses targeting mesothelin were elicited in several patients (12). A recent study indicated that anti-mesothelin antibodies and circulating mesothelin relate to the clinical state in ovarian cancer patients (13). Pastan and colleagues (14) developed an immunotoxin (SS1P) with a Fv for mesothelin. Two Phase I clinical trials were completed at the National Cancer Institute (National Institutes of Health, Bethesda, MD) and there was sufficient antitumor activity of SS1P to justify a Phase II trial. A chimeric antibody containing the mouse SS1 Fv for mesothelin was also developed and is currently examined in a Phase I clinical trial for ovarian cancer, mesothelioma, pancreatic cancer, and non-small cell lung cancer (15).Mucins are heavily glycosylated proteins found in the mucus layer or at the cell surface of many epitheliums (16). There are two structurally distinct families of mucins, secreted and membrane-bound forms. CA125 (also known as MUC16) was first identified in 1981 by OC125, a mAb that had been developed from mice immunized with human ovarian cancer cells (17). The first cDNA clones were reported in 2001 (18, 19). CA125 is a very large membrane-bound cell surface mucin, with an average molecular mass between 2.5 and 5 million daltons. It is also heavily glycosylated with both O-linked and N-linked oligosaccharides (20). The peptide backbone of CA125 is composed of the N-terminal region, extensive Ser/Thr/Pro-rich tandem repeats (TR) with 156 amino acids each with both N- and O-glycosylations, a SEA domain with high levels of O-glycosylation and a C-terminal region with a short cytoplasmic tail (19). The SEA domain was first identified as a module commonly found in sea urchin sperm protein, enterokinase and agrin (21, 22). The significance of the SEA domain in CA125 is not clear.CA125 was originally used as a biomarker in ovarian cancer due to its high expression in ovarian carcinomas and that it is shed into the serum (23). A majority (88%) of mesotheliomas are also CA125 positive on the cell membrane (24). It was shown that 25% of peritoneal mesotheliomas have high CA125 expression (25). The intensity of CA125 membranous expression is indistinguishable between ovarian carcinomas and peritoneal mesotheliomas. Gene expression analysis using the SAGE tag data base has shown that mesothelioma has the second highest co-expression of CA125 and mesothelin after ovarian cancer (26). Rump and colleagues (26) have shown that mesothelin binds to CA125 and that this interaction may mediate cell adhesion. Scholler et al. (27) recently showed that CA125/mesothelin-dependent cell attachment could be blocked with anti-CA125 antibodies. Because mesothelin is present on peritoneal mesothelium, there may be an important role for the mesothelin-CA125 interaction in the tumorigenesis of ovarian cancer and mesothelioma in the peritoneal cavity. The mesothelin binding site on CA125 may lie within the 156-amino acid TR units, indicating multimeric binding of mesothelin to CA125. It has been found that the extraordinarily abundant N-glycans on CA125, presumably in the TR region, are required for binding to both glycosylated and non-glycosylated mesothelin (28).Here, we identified the binding site of CA125 on mesothelin by use of truncated mutagenesis and alanine replacement approaches. We measured binding qualitatively by Western blot overlay assays and quantitatively by enzyme-linked immunosorbent assay (ELISA). We also evaluated the interaction of CA125 and mesothelin on cancer cells by flow cytometry. Furthermore, we have shown that a single chain mAb (SS1) recognized the CA125-binding domain and blocked the mesothelin-CA125 interaction on cancer cells. The identified CA125-binding domain-Fc fusion protein also significantly inhibited cancer cell adhesion. Our results suggest that conformation-sensitive structures of the region (296–359) are required and sufficient for specific binding of mesothelin to CA125. The domain proteins or the antibodies that block the mesothelin-CA125 interaction merit evaluation as new therapeutic agents in treating peritoneal malignant tumors.     

CEA-related cell adhesion molecule 1: a potent angiogenic factor and a major effector of vascular endothelial growth factor

CEA-related cell adhesion molecule 1 (CEACAM1) exhibits angiogenic properties in in vitro and in vivo angiogenesis assays. CEACAM1 purified from granulocytes and endothelial cell media as well as recombinant CEACAM1 expressed in HEK293 cells stimulate proliferation, chemotaxis, and capillary-like tube formation of human microvascular endothelial cells. They increase vascularization of chick chorioallantoic membrane and potentiate the effects of vascular endothelial growth factor (VEGF)165. VEGF165 increases CEACAM1 expression both on the mRNA and the protein level. VEGF165-induced endothelial tube formation is blocked by a monoclonal CEACAM1 antibody. These data suggest that CEACAM1 is a major effector of VEGF in the early microvessel formation. Since CEACAM1 is expressed in tumor microvessels but not in large blood vessels, CEACAM1 may be a target for the inhibition of tumor angiogenesis.