Arg-Gly-Asp-dependent occupancy of GPIIb/IIIa by applaggin: evidence for internalization and cycling of a platelet integrin

Using indirect immunofluorescence microscopy we examined the distribution and cycling of GPIIb/IIIa after binding to applaggin, a high-affinity Arg-Gly-Asp (RGD)--containing ligand. Resting, unfixed platelets were incubated with applaggin for 30 minutes at 37 degrees C, and bound applaggin was detected by an affinity-purified rabbit anti- applaggin antibody. Examination of intact cells showed a rim pattern for applaggin, consistent with its binding to the platelet surface. Staining of Triton X-100--permeabilized cells showed an intracellular pool of applaggin. Competition of applaggin binding by either AP-2, an anti-GPIIb/IIIa monoclonal antibody (MoAb) that blocks fibrinogen binding, or the synthetic peptide RGDW eliminated both surface and intracellular staining, indicating that applaggin is binding to GPIIb/IIIa in an RGD-dependent manner. Inhibition of platelet activation by PGE1 and theophylline had no effect on the observed staining patterns, indicating that cellular activation is not required for surface binding and subsequent internalization. To evaluate whether occupancy of functional binding sites on GPIIb/IIIa is required for internalization, we used mAb15, an anti-GPIIIa antibody that neither blocks fibrinogen binding nor induces the expression of ligand-induced binding sites on GPIIb/IIIa. In these studies mAb15 was internalized in a manner analogous to both AP-2 and applaggin, showing that occupancy of the RGD binding site is not required to initiate receptor internalization. To estimate the size of the newly internalized pool of applaggin, 125I-applaggin--binding studies were performed. Displacement of bound 125I-applaggin by excess unlabeled applaggin or EDTA showed that at least 17% of bound applaggin was nondisplaceable when binding was performed under conditions permitting membrane flow and internalization. These data indicate that GPIIb/IIIa is internalized in unstimulated platelets independent of cellular activation or occupancy of the functional binding site(s) of GPIIb/IIIa by RGD-containing ligands. Thus, internalization of GPIIb/IIIa may represent a mechanism by which the surface expression of this adhesion receptor is regulated.     

Heterogeneity of breakpoints of 11q23 rearrangements in hematologic malignancies identified with fluorescence in situ hybridization

Twenty-four patients whose cells contained a variety of 11q23 rearrangements, including translocations, insertions, and an inversion, were studied using fluorescence in situ hybridization with cosmid, phage, and plasmid probes mapped to 11q22-24. In 17 patients, the breakpoints of the common 11q23 translocations involving chromosomes 4, 6, 9, and 19 as well as some uncommon translocations involving 3q23, 17q25, 10p11, and an insertion 10;11 were all located in the breakpoint cluster region of the MLL gene, regardless of age, phenotype of disease, or involvement of a third chromosome. The breakpoints in 11q23 in the other 7 patients with a t(7;11)(p15;q23), inv(11)(p11q23), t(4;11)(q23;q23), der(5)t(5;11)(q13;q23), ins(10;11)(p11;q23q24), t(11;14)(q23;q11), or t(11;18;11) (p15;q21;q23) were located either centromeric to CD3D or telomeric to THY1. Thus, although most 11q23 rearrangements, involve the same breakpoint cluster region of MLL, there is heterogeneity in the breakpoint in some of the rare rearrangements.     

A selective cyclooxygenase 2 inhibitor suppresses the growth of H-ras-transformed rat intestinal epithelial cells

BACKGROUND & AIMS: Constitutive expression of cyclooxygenase 2 (COX-2) has been found in 85% of colorectal cancers. Ras mutations are found in 50% of colorectal adenocarcinomas. The aim of this study was to determine the role of COX-2 in ras-induced transformation in rat intestinal epithelial (RIE) cells. METHODS: Cell growth was determined by cell counts. The expression of COX-2 was examined by Northern and Western analyses. For tumorigenicity assays, cells were inoculated into dorsal subcutaneous tissue of athymic nude mice. DNA-fragmentation assays were performed to detect apoptosis. RESULTS: The expression of COX-2 was increased in RIE-Ras cells at both messenger RNA (9-fold) and protein (12-fold) levels. Prostaglandin I2 levels were elevated 2.15-fold in RIE-Ras cells. Serum deprivation further increased COX-2 expression 3.8-fold in RIE-Ras cells. Treatment with a selective COX-2 antagonist (SC58125) inhibited the growth of RIE-Ras cells through inhibition of cell proliferation and by induction of apoptosis. SC-58125 treatment reduced the colony formation in Matrigel by 83.0%. Intraperitoneal administration of SC-58125 suppressed RIE-Ras tumor growth in nude mice by 60.3% in 4 weeks. SC-58125 treatment also induced apoptosis in RIE-Ras cells as indicated by increased DNA fragmentation. CONCLUSIONS: Overexpression of COX-2 may contribute to tumorigenicity of ras-transformed intestinal epithelial cells. Selective inhibition of COX-2 activity inhibits growth of ras-transformed intestinal epithelial cells and induces apoptosis. (Gastroenterology 1997 Dec;113(6):1883-91)     

Cytogenetic and molecular delineation of a region of chromosome 7 commonly deleted in malignant myeloid diseases

Loss of a whole chromosome 7 or a deletion of the long arm, del(7q), are recurring abnormalities in malignant myeloid diseases. To determine the location of genes on 7q that are likely to play a role in leukemogenesis, we examined the deleted chromosome 7 homologs in a series of 81 patients with therapy-related or de novo myelodysplastic syndrome or acute myeloid leukemia. Our analysis showed that the deletions were interstitial and that there were two distinct deleted segments of 7q. The majority of patients (65 of 81 [80%]) had proximal breakpoints in bands q11-22 and distal breakpoints in q31-36; the smallest overlapping deleted segment was within q22. The remaining 16 patients had deletions involving the distal q arm with a commonly deleted segment of q32-33. To define the proximal deleted segment at 7q22 at a molecular level, we used fluorescence in situ hybridization with a panel of mapped yeast artificial chromosome (YAC) clones from 7q to examine 15 patients with deletion breakpoints in 7q22. We determined that the smallest overlapping deleted segment is contained in a well- defined YAC contig that spans 2 to 3 Mb. These studies delineate the region of 7q that must be searched to isolate a putative myeloid leukemia suppressor gene, and provide the necessary cloned DNA for more detailed physical mapping and gene isolation.     

Efficacy and safety of benralizumab in Japanese patients with severe,uncontrolled eosinophilic asthma

Background

In the Phase III CALIMA trial, benralizumab significantly reduced asthma exacerbations, increased lung function, and alleviated symptoms for patients with severe, uncontrolled eosinophilic asthma. The aim of this subgroup analysis was to evaluate the efficacy and safety of benralizumab for Japanese patients in the CALIMA trial.

Endoscopic duodenal stent versus surgical gastrojejunostomy for gastric outlet obstruction in patients with advanced pancreatic cancer

Background

Malignant gastric outlet obstruction (GOO) often develops in patients with advanced pancreatic cancer (APC). It is not clear whether endoscopic duodenal stenting (DS) or surgical gastrojejunostomy (GJJ) is preferable as palliative treatment.

Strong association between serum hepatocyte growth factor and metabolic syndrome

Hepatocyte growth factor (HGF) is one of the adipocytokines. We evaluated whether serum levels of HGF are related to the metabolic syndrome. A total of 1474 subjects of a general population free of liver, kidney, and lung diseases received a health examination. We measured blood pressure, waist circumference, body mass index, fasting plasma glucose, lipid profiles, serum insulin, liver enzymes, and HGF concentrations. Uni- and multivariate analyses for determinant of HGF were performed. In univariate analysis, all of the components (waist circumference, triglycerides, high-density lipoprotein-cholesterol, blood pressure, and fasting plasma glucose) of the metabolic syndrome and liver enzymes were significantly related to HGF levels. By the use of multiple stepwise regression analysis, HGF levels were significantly related to waist circumference (P < 0.001), high-density lipoprotein-cholesterol (P < 0.05, inversely), and liver enzymes (P < 0.001). HGF levels were higher (P < 0.05) in proportion to the accumulation of the number of the component of the metabolic syndrome. A significant association (P < 0.05) was shown between quartiles of HGF levels and the degree of abnormality of the component of the metabolic syndrome. In conclusion, our results indicate that serum HGF levels are strongly associated with the metabolic syndrome, independent of liver function.     

Patients preferences in chemotherapy for advanced non-small-cell lung cancer

OBJECTIVE: To determine how Japanese patients with lung cancer weigh potential survival, chemotherapy response rate, and symptom relief against the potential toxicity of different treatments in cancer chemotherapy. METHODS AND PATIENTS: We used a questionnaire describing a hypothetical situation about stage IV non-small-cell lung cancer. Seventy-three patients with lung cancer who had received chemotherapy and 120 patients with other respiratory disease as the control group were asked to rate the minimal benefit that would make two hypothetical treatments acceptable. For "chance of cure," "response but not cure," and "symptom relief," the subjects could give answers from 1% to 100% and for prolonging life could give answers from 1 to 60 months. RESULTS: Patients with lung cancer were significantly more likely than were patients with other respiratory diseases to accept either intensive or less-intensive treatments for a potentially small benefit for "chance of cure," "response but not cure," and "symptom relief". The degree of survival advantage that patients require before accepting cancer treatment with its associated toxicity varied widely. If their lives were prolonged 3 months, 19% and 21% of patients with lung cancer would choose to receive intensive and less-intensive treatment, respectively. When the chance of symptom relief was 70%, 73% of patients with lung cancer were willing to choose intensive chemotherapy. Factor associated with patients' choice of chemotherapy in both groups was age. CONCLUSION: Oncologists must consider the substantial range of attitudes to chemotherapy among patients when making treatment decisions and they must give patients the opportunity to be included in this process.     

Refractory proctosigmoiditis probably caused by inferior mesenteric vein ligation at sigmoidectomy

A case of refractory proctosigmoiditis is reported in a 65-year-old female post-sigmoidectomy patient. She had bloody diarrhea and abdominal pain 2 years after sigmoidectomy, in which the inferior mesenteric vein was ligated close to the inferior mesenteric artery root during the lymph node dissection, while the inferior mesenteric artery trunk and the last branch of the sigmoid arteries was preserved. The biopsied specimen obtained by a fiber optic colonoscopy was diagnosed as proctitis. Antidiarrheals, 5-aminosalicylic acid and steroid enemas showed only limited therapeutic effects. An angiography revealed a mild degree of rectal artery dilatation and tiny venous angiogenesis detected on the delayed phase images. Because the inferior mesenteric vein had been ligated, collateral veins developed to drain the blood on the distal side of the anastomosis to bilateral internal iliac veins. The venous blood of the descending colon (oral side of anastomosis) drained to left colic vein. The cause of rectosigmoiditis was considered to be venous congestion due to the inferior mesenteric vein ligation. A rectosigmoidectomy with reanastomosis using a double-stapling technique was performed, and the patient was discharged without symptoms.