Double ventricular responses during extrastimulation of atrioventricular nodal reentrant tachycardia

In patients with dual atrioventricular (AV) nodal pathways,double ventricular responses to a single atrial depolarizationhave been shown to occur, but virtually only during a trialpacing in sinus rhythm. We report on a patient with a slow-fastform of AV nodal reentrant tachycardia who exhibited doubleventricular responses following extrastimulation during AV nodalreentrant tachycardia. The phenomenon of double ventricularresponses during the tachycardia was demonstrated by ex trastimulationfrom the proximal coronary sinus. Retrograde unidirectionalblock in the slow pathway, and an anterograde effective refractoryperiod that was shorter in the fast pathway than that in theslow pathway, are suggested.     

Class IC Antiarrhythmic Drugs, Flecainide and Pilsicainide, Produce ST Segment Elevation Simulating Inferior Myocardial Ischemia

ST Elevation with Flecainide and Pilsicainide . Flecainide and pilsicainide, Class IC antiarrhythmic drugs with slow kinetics, were administered to a 64-year-old man experiencing ventricular tachycardia. Both drugs suppressed the arrhythmia, but caused ST segment elevation in leads II, III, and aVF. No evidence of ischemic heart disease was detected. Withdrawal of the drugs eliminated the ST change. Because these drugs frequently are used to treat tachyarrhythmias in patients who may present with chest pain, this rare ECG manifestation of Class IC drugs should he recognized to avoid misdiagnosis of acute interior myocardial infarction.     

Suppression of Torsades de Pointes by Biventricular Pacing in a Patient with Long QT Syndrome

This report describes a case of a patient with long QT syndrome (LQTS) with recurrent episodes of torsades de pointes (TdP). Use of biventricular pacing (BiVP) resulted in a shorter QT interval and a shorter T‐peak‐end interval and prevented further episodes of TdP. These findings suggest that BiVP may be helpful in patients with LQTS and refractory TdP.     

The Acute and Chronic Toxicities of Nivalenol in Mice

The Acute and Chronic Toxicities of Nivalenol in Mice. Ryu,J.-C, Ohtsubo, K., Izumiy-ama, N., Nakamura, JL, Tanaka, T.,Yamamura, H., and Ueno, Y. (1988). Fundam. Appl Toxicol. 11,38–47. In an attempt to ascertain precisely the toxiceffects of nivalenol (N1V), we conducted the determination ofLD50 values, and interim kills during the carcinogenic studyin mice. LD50 values (mg/kg) of NIV in 6-week-old male ddY micewere determined as 38.9 (po), 7.4 (ip), 7.2 (sc), and 7.3 (iv).Seven-week-old female C57BL/6CrSlc SPF mice were fed diets containing0, 6, 12, and 30 ppm (mg/kg) NIV over 1 year, and were assessedfor effects on body weight gain, feed efficiency, terminai organweights, hematology, and histopathology. The rates of body weightgain and feed efficiency showed a good dose-dependent correlationin all experimental periods. Gross and histopathological evaluationof the liver, thymus, spleen, kidneys, stomach, adrenal glands,pituitary gland, ovaries, sternum, bone marrow, lymph node,brain, and small intestines with or without Peyer's patch portionfrom control and all NIV-exposed mice revealed that these tissueswere normal in appearance and in histopathological structure.Also, no changes were observed in the ultrastructural studieson the bone marrow. Dietary NIV did, however, cause dose-dependentdecreases of absolute organ weights (mg) and increases of relativeorgan weights (mg/g body weight) in the terminal organ weightsrecorded. A significant leukopenia was observed in the 30 ppmgroup at 6 months and in all NIV-treated groups at 1 year. Nomarked changes were observed in the other hematological parameters.These results indicated that 6 ppm or more of dietary NIV for1 year showed a characteristic toxic effect of trichothecenemycotoxins in mice.     

Synthesis and stabilization of amino and carboxy terminal constrained collagenous peptides

Short collagenous peptides cross-linked at their amino and carboxy termini with Lys-Lys-dimer template(s) were synthesized, and the effect of the cross-linking on their stabilities was investigated by thermal denaturation experiments. Two chemoselective ligations were used for the construction of the amino and the carboxy cross-linked peptides. The thermal transition temperature (T_m) and the standard free energies (ΔG°) of the cross-linked collagenous peptides increased, and the thermal stabilization effect corresponded to an elongation by two units of the Gly-Pro-Hyp triad. The van't Hoff enthalpy (ΔH°) and the entropy (ΔS°) values of the cross-linked peptides increased with chain elongation, although the increments were smaller than those of the linear peptides. When the same chain lengths were compared, the ΔH° was increased and the ΔS° was nearly the same or increased by the cross-linking. These results suggest that the cross-linking of the collagenous peptides with the Lys-Lys-dimer template(s) for stabilization contributes to the enthalpic effect, rather than the entropic effect.     

Expression of Lewis X-related antigens in adenocarcinomas of lung

Fifty primary lung adenocarcinomas were examined immunohistochemically using monoclonal antibodies to determine changes in the expression of N-acetyl-lactosamine (blood group type-2 chain), Le^x, Le^Y and sialyl Le^x-i. These antigens were expressed in 60%, 70%, 90% and 94% of carcinomas, respectively; in 8%, 12%, 56% and 86% of normal broncho-bronchiolar epithelium; and in 32%, 0%, 100% and 0% of normal alveolar epithelium. The greater the complexity of the antigenic structure, the greater the incidence of positive staining in the adenocarcinomas. Although the more complex antigens such as sialyl Le^x-i and Le^Y have also been demonstrated in the sera of lung cancer patients, they were not always cancer-selective in our immunohistochemical study. In contrast, the less complex antigens such as N-acetyl-lactosamine (type-2 chain) and Le^x seem to be cancer-selective, as they showed low positivity in normal lung tissue.