Comparative next-generation mapping of the Phytophthora infestans resistance gene Rpi-dlc2 in a European accession of Solanum dulcamara.

Phytophthora infestans, the causal agent of late blight, remains the main threat to potato production worldwide. Screening of 19 accessions of Solanum dulcamara with P. infestans isolate Ipo82001 in detached leaf assays revealed strong resistance in an individual belonging to accession A54750069-1. This plant was crossed with a susceptible genotype, and an F(1) population consisting of 63 individuals was obtained. This population segregated for resistance in 1:1 ratio, both in detached leaf assays and in an open-field experiment. Presence of the formerly mapped Rpi-dlc1 gene as the cause of the observed segregating resistance could be excluded. Subsequently, AFLP analyses using 128 primer combinations enabled identification of five markers linked to a novel resistance gene named Rpi-dlc2. AFLP markers did not show sequence similarity to the tomato and potato genomes, hampering comparative genetic positioning of the gene. For this reason we used next-generation mapping (NGM), an approach that exploits direct sequencing of DNA (in our case: cDNA) pools from bulked segregants to calculate the genetic distance between SNPs and the locus of interest. Plotting of these genetic distances on the tomato and potato genetic map and subsequent PCR-based marker analysis positioned the gene on chromosome 10, in a region overlapping with the Rpi-ber/ber1 and -ber2 loci from S. berthaultii. Pyramiding of Rpi-dlc2 and Rpi-dlc1 significantly increased resistance to P. infestans, compared with individuals containing only one of the genes, showing the usefulness of this strategy to enhance resistance against Phytophthora.

Early intravenous administration of metoprolol enhances myocardial salvage by thrombolysis with recombinant tissue-type plasminogen activator after thrombotic coronary artery occlusion in the dog by improvement of the collateral blood flow to the area at risk.

OBJECTIVES: We studied the effects of beta 1-adrenergic blockade preceding thrombolysis on hemodynamic variables, myocardial blood flow and infarct size in a canine model of thrombotic occlusion of the left anterior descending coronary artery. BACKGROUND: Previous work suggested a reduction in infarct size and improvement in left ventricular function by intravenous beta-blockade preceding thrombolysis. METHODS: Experiments were conducted in 34 anesthetized dogs; 17 received 0.975 mg/kg body weight of metoprolol intravenously starting 15 min after occlusion, and thrombolysis was initiated 60 min after occlusion. Seventeen dogs received saline solution followed by thrombolysis. Coronary blood flow was measured by radioactive microspheres, infarct size by a dye method, hemodynamic variables by catheter-tipped pressure transducers and cardiac output by the thermodilution method. RESULTS: Infarct size in metoprolol- and placebo-treated dogs was 23.62 +/- 18.04% and 41.50 +/- 16.03% of area at risk, respectively (p < 0.01). Before occlusion, myocardial blood flow and hemodynamic variables were similar. Sixty minutes after occlusion, cardiac output (1.94 +/- 0.41 vs. 2.32 +/- 0.68 liters/min, p < 0.01) was lower in the metoprolol-treated dogs. Collateral flow to the area at risk (17.27 +/- 7.44 vs. 10.25 +/- 5.33) and to its epicardial (21.68 +/- 8.04 vs. 11.5 +/- 6.10), midmyocardial (14.30 +/- 8.63 vs. 7.35 +/- 4.94) and endocardial (13.18 +/- 8.21 vs. 6.26 +/- 5.34 cm3/min per 100 g) layers was higher (p < or = 0.05) in the metoprolol-treated dogs. The ratio of epicardial flow area at risk/circumflex territory was inversely correlated to infarct size (r = -0.69, p < 0.01). After 5 min of occlusion, collateral flow was comparable in the five dogs of each group; over the next 55 min it remained constant in the metoprolol group but decreased in the placebo dogs. CONCLUSIONS: Intravenous metoprolol, administered before thrombolysis, enhances infarct size limitation, partly by improvement of collateral flow to area at risk.

Reduction in infarct size and enhanced recovery of systolic function after coronary thrombolysis with tissue-type plasminogen activator combined with beta-adrenergic blockade with metoprolol.

The effect of beta-adrenergic blockade on the salvage and functional recovery of reperfused myocardium was investigated in anesthetized dogs. Immediately after thrombotic occlusion of the left anterior descending coronary artery, the cardioselective beta-blocking agent metoprolol was given intravenously at a dose of 0.5 mg/kg infused over 10 min. One hour after the onset of occlusion, recanalization was initiated by intravenous infusion of recombinant human tissue-type plasminogen activator (rt-PA, 10 micrograms/kg/min for 30 min). Anatomic infarct size expressed as percent of the left ventricular mass (I/LV), global ejection fraction, and mean systolic shortening of the segmental radii (SS) of the infarcted area were measured either after 24 hr or 1 week in six groups of six dogs each: group I (rt-PA + metoprolol, evaluated at 24 hr), group II (rt-PA + metoprolol, evaluated at 1 week, group III (rt-PA alone, evaluated at 24 hr), group IV (rt-PA alone, evaluated at 1 week), group V (persistent occlusion, evaluated at 24 hr), and group VI (persistent occlusion, evaluated at 1 week). The smallest infarcts were found in reperfused dogs given metoprolol, but the differences from dogs receiving rt-PA alone were not statistically significant (I/LV, expressed as mean +/- SEM: 5.5 +/- 0.9% in group I, 6.7 +/- 1.9% in group II, 15.4 +/- 5.0% in group III, 11.4 +/- 3.5% in group IV, 23.6 +/- 2.5% in group V, and 26.9 +/- 2.3% in group VI).(ABSTRACT TRUNCATED AT 250 WORDS)

Surgical treatment of acute, massive lung embolism. Results and follow-up.

Between 1970 and 1984 the diagnosis of acute, massive lung embolism was made 30 times in our department. In 29 patients the clinical diagnosis was correct and a Trendelenburg operation under extra-corporeal circulation was performed. In 18 cases there was an operation in the immediate preoperative course. In 1 case there was a combination of operation and the use of contraceptives. 3 cases were immobilized by a plaster of Paris cast. In 4 cases the use of oral contraceptives and in 3 patients the history of chronic recurrent lung embolism were evident. The mean immobilisation time was 15 days. In 24 cases the diagnosis was made only on the base of the clinical anamnesis, and examination, E.C.G. and chest radiography. In 4 cases angiography and in 1 patient the scintigraphy confirmed the diagnosis. Preoperatively 28 patients were in severe shock. One patient was operated electively. 14 patients needed external cardiac massage. In all cases clots were found in the left pulmonary artery, 28 in the right pulmonary artery, in 3 cases clots in the right atrium, 3 in the right ventricle and three in the inferior caval vein. Nine De Weese caval vein clips were inserted and one Mobin-Uddin filter. Postoperatively 18 patients were alive and well without sequelae. Two patients developed a cerebro-vascular accident (CVA) with one complete recovery. Ten patients died. Postoperative treatment consisted of I.V. heparin administration immediately after surgery and 6 months of oral anticoagulants. Except for chronic recurrent lung embolism the pulmonary function tests were excellent postoperatively without recurrence of the disease.