Selection of rainbow trout resistant to viral haemorrhagic septicaemia virus and transmission of resistance by gynogenesis

In 1984 a programme of selection for resistance to viral haemorrhagic septicaemia virus (VHSV) in rainbow trout was initiated. The progenies of 14 males were submitted to a VHSV waterborne challenge. The mortality ranged from 30 to 95% and the heritability of resistance was estimated to be 0.63 +/- 0.26. One male consistently provided the most resistant offspring, and the second generation was produced from sires and dams selected among these families. The mean resistance improved and several females giving birth to resistant offspring were identified (0-10% mortality while the mortality in the controls was from 70 to 90%). The meiotic gynogenetic progeny of these females also demonstrated high resistance (mortality less than 10%). The role of superficial tissues in the resistance was confirmed and there was a striking difference in the growth of VHSV in fins excised and infected in vitro. The fins from resistant fish replicated the virus poorly as compared with the fins of susceptible fish.     

Complementary cancer treatments: hope or hazard?

Complementary therapies are frequently used by cancer patients, yet the area is a minefield of hazards and hopes. A distinction between cure and care seems helpful. There are no effective complementary cures and most options that are promoted carry a distinct and, in certain cases, fatal risk. Complementary cancer care is more acceptable and there are options that can be shown to ease suffering. Vis a vis the popularity of complementary cancer treatments, the lack of scientific evidence for most therapies seems unacceptable. The call for more rigorous research is loud and clear.     

Savings in relearning: II. On the formation of behavior-based trait associations and inferences.

Five experiments based on Carlston and Skowronski's (1994) relearning paradigm suggest that people spontaneously derive trait knowledge about actors from behaviors but that this knowledge may reflect either explicit trait inference processes or implicit actor–trait associations. Experiments 1 and 2 found that inference-instructed and control Ss showed equivalent savings in subsequent efforts to learn actor–trait pairs but not when instructed Ss initially inferred the wrong trait. Experiment 3 showed that savings were equivalent for stimuli from different sources, and Experiment 4 showed that savings effects persisted even when the target was only incidentally associated with a stimulus behavior. Finally, Experiment 5 suggests that after several days, even explicit trait inferences can become inaccessible to intentional retrieval, although the earlier experiments show that they continue to exert an implicit effect on learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Influence of impact-ionization-induced base current reversal onbipolar transistor parameters

In this paper we describe a set of measurements representing a complete characterization of impact-ionization effects in bipolar transistors. We demonstrate that impact-ionization significantly influences the dependence of base resistance on current and voltages applied to the device. A dc method for the simultaneous extraction of all parasitic resistances in bipolar transistors is presented. The method can separate the influence of current-crowding on the base resistance from that of base width and conductivity modulation; the collector parasitic resistance is measured in the active region. Starting from the parameters extracted by means of these techniques, a complete and accurate circuit-model of impact-ionization effects can be defined     

Si/SiGe epitaxial-base transistors. I. Materials, physics, andcircuits

A detailed review of SiGe epitaxial base technology is presented, which chronicles the progression of research from materials deposition through device and integration demonstrations, culminating in the first SiGe integrated circuit application. In part I of this paper, the requirements and processes for high-quality SiGe film preparation are discussed, with emphasis on fundamental principles. A detailed overview of SiGe HBT device design and implications for circuit applications is then presented     

Preferred strategies for secondary infrainguinal bypass: lessons learned from 300 consecutive reoperations

PURPOSE: To determine the optimal surgical strategies in reoperative infrainguinal bypass, we reviewed our results in 300 consecutive secondary bypasses in 251 patients operated on between Jan. 1, 1975, and Nov. 1, 1993. METHODS: There were 168 men (67%) and 83 women (33%), with a mean age of 64.8 years and a typical distribution of risk factors including smoking (76.4%), diabetes (33.7%), and coronary artery disease (47.1%). The indications for surgery were limb-threatening ischemia in 83.5% and severe claudication in 16.5% of patients. The majority of conduits (n = 213) were autogenous vein and were composed of a single segment of greater saphenous vein in 121 bypasses (57%) and various alternative veins including composite, arm, and lesser saphenous vein in 92 bypasses (43%). Prosthetic conduits included 69 polytetrafluoroethylene, 16 umbilical vein, and two Dacron grafts. RESULTS: There was one perioperative death (0.3%) and a 25% total morbidity rate including a 1.7% myocardial infarction rate. There was a 28.6% early (< 30 days) graft failure and 10.7% early amputation rate for prosthetic bypass grafts compared with 13.6% early graft failure and 5.6% early amputation rates for vein grafts. Autogenous vein bypasses had higher 5-year secondary patency rates than had prosthetic grafts (51.5% +/- 4.6% vs 27.4% +/- 6.1%, p < 0.001). Results with autogenous vein bypass improved significantly from the 1975 to 1984 to the 1985 to 1993 interval with 5-year secondary patency rates increasing from 38.3% +/- 6.9% to 59.1% +/- 5.8% (p = 0.017) and 5-year limb-salvage rates increasing from 40.4% +/- 7.6% to 72.4% +/- 6.6% (p < 0.001). Vein grafts to the popliteal and tibial outflow levels had equivalent long-term results. Vein grafts completed for claudication demonstrated results superior to those for limb salvage, with a 5-year secondary patency rate of 75.8% +/- 8.1% versus 52.3% +/- 7.9% (p = 0.048). Secondary autogenous vein bypass grafting performed after early primary graft failure (< 3 months) did particularly poorly, with only a 27.2% +/- 7.7% 4-year secondary patency rate. Greater saphenous veins tended to perform better than alternative vein bypasses, with a 5-year secondary patency rate of 68.5% +/- 6.0% compared with 48.3% +/- 10.5% (p = 0.09) and a 5-year limb-salvage rate of 77.8% +/- 7.4% versus 54.2% +/- 11.8% (p = 0.046). CONCLUSIONS: When patients suffer a recurrence of limb-threatening ischemia at the time of infrainguinal graft failure, aggressive attempts at secondary revascularization with autogenous vein are warranted based on the low surgical morbidity and mortality rates and the improved patency and limb salvage rates that are currently attainable.     

Antral gastritis in chronic alcoholism. Role of cirrhosis and Helicobacter pylori

OBJECTIVES: Antral gastritis is frequent in alcoholics. The role of H. pylori in the pathogenesis of gastritis in these patients is not well known. The aim of our study was to study the role of H. pylori and cirrhosis in the pathogenesis of antral gastritis in alcoholic patients. METHODS: Seventy-nine patients were included in the study. All underwent upper gastrointestinal tract endoscopy with antral biopsies, independently of the presence of abdominal pain, and had serological examination for H. pylori antibodies. RESULTS: Cirrhosis and gastritis were present in 50 and 40 patients respectively, H. pylori serological assay and histological identification of the bacterium were positive in 35 (44%) and 19 (24%) patients respectively. Discrepancy between the 2 tests were observed more frequently in cirrhotic patients. A positive serology with a negative histologic examination for H. pylori was present for 18 cirrhotic and 4 noncirrhotic patients (p < 0.05). A gastritis without evidence of H. pylori was more frequent in cirrhotic than in noncirrhotic patients. H. pylori was histologically present in 11 of 29 cirrhotic patients and in 8 of the 11 noncirrhotic patients with a gastritis (p < 0.05). CONCLUSIONS: Discrepancies between histological examination and H. pylori serology in patients with cirrhosis might be due to the inhospitable environment for H. pylori in case of portal hypertension; the positive serology could be in relation with a past infection.     

P2U-purinergic receptor activation mediates inhibition of cAMP accumulation in cultured renal mesangial cells

Extracellular ATP has been reported to exert mitogenic and contractile effects on cultured renal mesangial cells (MCs). Since it is possible that these actions involve changes in the cAMP second messenger system, we examined the effect of extracellular nucleotides on the accumulation of cAMP in rat MCs. ATP, UTP and adenosine 5'-0-(3-thio)triphosphate (ATP gamma S) (100 microM) had no significant effects on baseline cAMP levels, but inhibited forskolin-stimulated accumulation of cAMP by 21-75% in the presence of the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX). Maximal inhibitory effects were observed at 100 microM of ATP gamma S with a threshold dose of 1 microM. ATP gamma S, ATP and UTP were the most potent inhibitors indicating stimulation of the P2u receptor. The P2x agonists adenosine 5'-(alpha, beta-methylene) triphosphate and adenosine 5'-(beta, gamma-methylene) triphosphate, and the P2y agonist 2-methylthio-ATP did not affect cAMP accumulation. Treatment with the P2 receptor antagonist suramin (200 microM) reduced the inhibition by 58%. The inhibitory effects of the nucleotides were significantly attenuated by preincubation with pertussis toxin (10-100 ng/ml). Inhibition of phospholipase C and protein kinase C did not prevent the inhibitory effect of the nucleotides. Inhibitors of forskolin-stimulated cAMP accumulation had different effects on DNA synthesis in cultured MCs as measured by 3H-thymidine uptake at 48 h: ATP, ATP gamma S and the inhibitor of adenylyl cyclase, SQ 22536, stimulated DNA synthesis in MCs, while UTP showed no significant mitogenic effect. Agents which increased baseline levels of intracellular cAMP (forskolin, IBMX, dibutyryl-cAMP) significantly diminished DNA synthesis in MCs. The results indicate that the P2u-purinergic receptor mediates inhibition of forskolin-induced cAMP accumulation which is likely due to inhibition of adenylyl cyclase. This effect appears to be partially mediated by PTX-sensitive G proteins. While the increase in cAMP accumulation is anti-mitogenic, inhibition of cAMP accumulation by P2u receptors is not correlated with MC growth control. Thus, additional mechanisms other than inhibition of cAMP accumulation by P2u receptors are likely to be involved in the mitogenesis of extracellular ATP.