Echinococcus granulosus: Diagnosis of human hydatid disease by the indirect haemoagglutination reaction with antigens from hydatid fluid and scoleces

Tassi Carmelo, Dottorini Silvio, Scalise Giorgio and Geranio Nadia. 1981. Echinococcus granulosus: diagnosis of human hydatid disease by the Indirect Haemoagglutination reaction with antigens from hydatid fluid and scoleces. International Journal for Parasitology11: 85–88. Various antigenic fractions were prepared from sheep hydatid fluid and scoleces of Echinococcus granulosus by ammonium sulphate salting out. Sheep red blood cells were sensitized with all antigenic preparations and tested, by Indirect Haemoagglutination reaction, against 63 sera from humans with hydatid disease and 163 controls. The greatest sensitivity was obtained with the ‘0·8 M fraction’ and ‘Band 7’ from hydatid fluid. The specificity was excellent for all antigens examined.     

Neural encoding schemes of tactile information in afferent activity of the vibrissal system

When rats acquire sensory information by actively moving their vibrissae, a neural code is manifested at different levels of the sensory system. Behavioral studies in tactile discrimination agree that rats can distinguish different roughness surfaces by whisking their vibrissae. The present study explores the existence of neural encoding in the afferent activity of one vibrissal nerve. Two neural encoding schemes based on “events” were proposed (cumulative event count and median inter-event time). The events were detected by using an event detection algorithm based on multiscale decomposition of the signal (Continuous Wavelet Transform). The encoding schemes were quantitatively evaluated through the maximum amount of information which was obtained by the Shannon’s mutual information formula. Moreover, the effect of difference distances between rat snout and swept surfaces on the information values was also studied. We found that roughness information was encoded by events of 0.8 ms duration in the cumulative event count and event of 1.0 to 1.6 ms duration in the median inter-event count. It was also observed that an extreme decrease of the distance between rat snout and swept surfaces significantly reduces the information values and the capacity to discriminate among the sweep situations.     

High Soluble Endoglin Levels Do Not Induce Endothelial Dysfunction in Mouse Aorta

Increased levels of a soluble form of endoglin (sEng) circulating in plasma have been detected in various pathological conditions related to cardiovascular system. High concentration of sEng was also proposed to contribute to the development of endothelial dysfunction, but there is no direct evidence to support this hypothesis. Therefore, in the present work we analyzed whether high sEng levels induce endothelial dysfunction in aorta by using transgenic mice with high expression of human sEng. Transgenic mice with high expression of human sEng on CBAxC57Bl/6J background (Sol-Eng ⁺) and age-matched transgenic littermates that do not develop high levels of human soluble endoglin (control animals in this study) on chow diet were used. As expected, male and female Sol-Eng ⁺ transgenic mice showed higher levels of plasma concentrations of human sEng as well as increased blood arterial pressure, as compared to control animals. Functional analysis either in vivo or ex vivo in isolated aorta demonstrated that the endothelium-dependent vascular function was similar in Sol-Eng ⁺ and control mice. In addition, Western blot analysis showed no differences between Sol-Eng ⁺ and control mice in the protein expression levels of endoglin, endothelial NO-synthase (eNOS) and pro-inflammatory ICAM-1 and VCAM-1 from aorta. Our results demonstrate that high levels of soluble endoglin alone do not induce endothelial dysfunction in Sol-Eng ⁺ mice. However, these data do not rule out the possibility that soluble endoglin might contribute to alteration of endothelial function in combination with other risk factors related to cardiovascular disorders.     

An Isolated Working Heart System for Large Animal Models

Since its introduction in the late 19^th century, the Langendorff isolated heart perfusion apparatus, and the subsequent development of the working heart model, have been invaluable tools for studying cardiovascular function and disease^1-15. Although the Langendorff heart preparation can be used for any mammalian heart, most studies involving this apparatus use small animal models (e.g., mouse, rat, and rabbit) due to the increased complexity of systems for larger mammals^1,3,11. One major difficulty is ensuring a constant coronary perfusion pressure over a range of different heart sizes – a key component of any experiment utilizing this device^1,11. By replacing the classic hydrostatic afterload column with a centrifugal pump, the Langendorff working heart apparatus described below allows for easy adjustment and tight regulation of perfusion pressures, meaning the same set-up can be used for various species or heart sizes. Furthermore, this configuration can also seamlessly switch between constant pressure or constant flow during reperfusion, depending on the user’s preferences. The open nature of this setup, despite making temperature regulation more difficult than other designs, allows for easy collection of effluent and ventricular pressure-volume data.     

Different affinity states of CCK1 receptors on pancreatic acini and gastric smooth muscle in the rat

It has recently been shown that—after chronic cholecystokinin (CCK) treatment—an adaptation of pancreatic secretory but not gastric motor function does occur. Recent studies indicate that the CCK₁-receptor exists in two (i.e. high and low) affinity states, which could be distinguished by the CCK-analogue JMV-180. CCK occupancy of high and low affinity sites is thought to be related to the initiation of different intracellular events and consequent biological responses. Affinity states of CCK₁-receptors on pancreas and gastrointestinal (GI) smooth muscle could be different and this can offer an explanation for the different effects of CCK on pancreatic and gastric growth. We therefore studied the affinity states of CCK₁-receptors on isolated rat pancreatic acini and gastric smooth muscle preparations. When acini were incubated with increasing concentrations of CCK-8, a biphasic (i.e. stimulation followed by inhibition) effect on amylase release was observed. JMV-180 caused only stimulation of enzyme release and combined JMV-180 and CCK stimulation (at submaximal doses) resulted in an additive secretory response. CCK-8 induced contractions of pyloric, antral and fundic muscle in a concentration-dependent manner. The response was monophasic, reaching a plateau. JMV-180 had only a very weak effect on these preparations. On the contrary, it inhibited CCK-induced contractions in a competitive manner, the concentration–response curve to CCK being shifted to the right by the CCK analogue. Our data suggest that the affinity states of CCK₁-receptors on rat pancreatic and gastric tissue are different. On pancreatic acini CCK₁-receptors exist in both high- and low-affinity states whose occupation is followed by the sequence of intracellular events leading to growth. In contrast, occupation of low affinity receptors (the only ones present in the GI smooth muscle) does not lead to cell proliferation. This difference therefore explains the different adaptive response of the pancreas and the stomach to chronic CCK administration. Furthermore, different affinity states of CCK₁-receptors may mediate different functions of the digestive tract.     

Activity of plasma membrane H+-ATPase and expression of PMA1 and PMA2 genes in Saccharomyces cerevisiae cells grown at optimal and low pH

Cells of Saccharomyces cerevisiae grown in media with an initial pH of 2.5–6.0, acidified with a strong acid (HCl), exhibited the highest plasma membrane H⁺-ATPase-specific activity at an initial pH of 6.0. At a lower pH (above pH 2.5) ATPase activity (62–83% of the maximum level) still allowed optimal growth. At pH 2.5, ATPase activity was about 30% of the maximum value and growth was impaired. Quantitative immunoassays showed that the content of ATPase protein in the plasma membrane was similar across the entire pH range tested, although slightly lower at pH 2.5. The decrease of plasma membrane ATPase activity in cells grown at low pH was partially accounted for by its in vitro stability, which decreased sharply at pH below 5.5, although the reduction of activity was far below the values expected from in vitro measurements. Yeast growth under acid stress changed the pattern of gene expression observed at optimal pH. The level of mRNA from the essential plasma-membrane-ATPase-encoding gene PMA1 was reduced by 50% in cells grown at pH 2.5 as compared with cells grown at the optimal pH 5.0, although the content of ATPase in the plasma membrane was only modestly reduced. As observed in response to other kinds of stress, the PMA2 promoter at the optimal pH was up to eightfold more efficient in cells grown at pH 2.5, although it remained several hundred times less efficient than that of the PMA1 gene. Received: 22 April 1996 / Accepted: 6 August 1996