Mediastinal tuberculous lymphadenitis: CT manifestations

An analysis was done of computed tomographic (CT) scans of 23 Korean patients who had presented with a mediastinal or hilar mass on plain chest radiographs and had subsequently been found to have tuberculous lymphadenitis. Most patients were young adults. Findings of pulmonary tuberculosis were seen on plain radiographs in 14 patients. On CT, findings were of an overwhelming preponderance of involvement of the right paratracheal and tracheobronchial nodes. After injection of contrast medium, nodes larger than 2 cm in diameter invariably showed central areas of relative low density and peripheral rim enhancement. Enhanced walls were usually irregular in thickness. Some smaller nodes did not show low-density areas, but instead showed varying degrees of homogeneous enhancement. Although metastatic nodes can be of low density, experience in this study suggests that mediastinal lymphadenopathy in a young adult with the CT findings described above is characteristic enough to support a diagnosis of tuberculosis.     

DDAVP enhances platelet adherence and platelet aggregate growth on human artery subendothelium

The effect of intravenous 1-deamino (8-D-arginine)vasopressin (DDAVP) administration on platelet interaction with human artery subendothelium was investigated with flowing blood from five normal individuals and 12 patients with von Willebrand's disease (vWD). Three of the patients were diagnosed as vWD subtype I, four as subtype IIa, and five as subtype IIb. DDAVP administration to normals enhanced platelet adherence, in parallel with increasing plasma levels of factor VIII- related antigen ( FVIIIR :Ag) and ristocetin cofactor activity ( FVIIIR :RCF). Platelet aggregate formation was transiently increased within 90 minutes. Platelet adherence in patient blood before DDAVP infusion was subnormal. In patients with subtype I, administration of DDAVP normalized the bleeding time, enhanced the platelet adherence, and transiently improved the platelet aggregate formation. The platelet adherence was more corrected than would have been expected on the basis of the FVIIIR :Ag and FVIIIR :RCF levels. In patients with subtype IIa, infusion of DDAVP increased the FVIIIR :Ag levels approximately threefold, without affecting the FVIIIR :RCF levels, and in only two of four patients was a transiently enhanced platelet adherence with a corresponding shortening of the bleeding time observed. In patients with subtype IIb, administration of DDAVP increased the FVIIIR :Ag levels about threefold and the FVIIIR :RCF levels five to tenfold, but decreased the platelet adherence significantly. The bleeding time values were not normalized. A close association between the bleeding time values and corresponding platelet adherence values before and after DDAVP infusion was observed. Normalization of the bleeding time was paralleled with normalization of platelet adherence. We conclude that DDAVP improves the primary hemostasis by causing enhanced FVIII- vWF-mediated platelet adherence. DDAVP has little or no effect on the bleeding time in patients with subtype IIa and subtype IIb, because the platelet adherence is not normalized.     

Evaluation of the biliary tract: The value of performing magnetic resonance cholangiopancreatography in conjunction with a 3‐D spoiled gradient‐echo gadolinium enhanced dynamic sequence

The 3‐D gradient‐echo (GRE) sequence allows thinner sections and better resolution of biliary obstruction. When the presence of biliary obstruction is identified using magnetic resonance cholangiopancreatography, the addition of the 3‐D GRE sequence may be helpful for diagnosing biliary obstruction. By showing the changes in the bile duct wall, within the duct lumen and around the bile duct, this technique can be helpful for distinguishing benign from malignant stricture as well as a stone from an enhancing intraluminal mass.     

Helicobacter pylori stimulates inducible nitric oxide synthase expression and activity in a murine macrophage cell line

BACKGROUND & AIMS: Helicobacter pylori uniquely colonizes the human stomach and produces gastric mucosal inflammation. High-output nitric oxide production by inducible nitric oxide synthase (iNOS) is associated with immune activation and tissue injury. Because mononuclear cells comprise a major part of the cellular inflammatory response to H. pylori infection, the ability of H. pylori to induce iNOS in macrophages was assessed. METHODS: H. pylori preparations were added to RAW 264.7 murine macrophages, and iNOS expression was assessed by Northern blot analysis, enzyme activity assay, and NO2- release. RESULTS: Both whole H. pylori and French press lysates induced concentration-dependent NO2- production, with peak levels 20-fold above control. These findings were paralleled by marked increases in iNOS messenger RNA and enzyme activity levels. iNOS expression was synergistically increased with interferon gamma, indicating that the H. pylori effect can be amplified by other macrophage-activating factors. Studies of lipopolysaccharide (LPS) content and polymyxin B inhibition of LPS suggested that the H. pylori effect was attributable to both LPS- dependent and -independent mechanisms. CONCLUSIONS: iNOS expression in macrophages is activated by highly stable H. pylori products and may play an important role in the pathogenesis of H. pylori-associated gastric mucosal disease. (Gastroenterology 1996 Dec;111(6):1524-33)