Detection of Bm86 antigen in different strains of Boophilus microplus and effectiveness of immunization with recombinant Bm86

The control of tick populations by using conventional strategies poses several problems, including the appearance of organophosphate resistant strains, among others. The possibility of using alternative strategies such as vaccination with tick antigens has been suggested by several authors. One particular antigen (Bm86) has been described and shown to be able to induce a protective immunity against the cattle tick Boophilus microplus. In this paper we demonstrate by means of immunohistochemical staining that this antigen is conserved among several strains of this species. These results correlate with those showing that animals vaccinated with a preparation of recombinant Bm86 were protected against challenge with the four different strains tested, including one resistant to organophosphates. These results favour the immunization with recombinant Bm86 for the control of the cattle tick B. microplus.     

EFFECT OF THORACIC AND ABDOMINAL PRESSURE CHANGES ON THE EPIDURAL SPACE PRESSURE

The effect of changes in superior and inferior vena caval pressureson the pressure in the epidural space was studied in fifteenunpremedicated patients and in five dogs. It was found thatthe epidural space, unlike the subarachnoid compartment hadtwo types of pressure oscillations during spontaneous respiration.A superior vena caval-like pattern was found in the cervico-thoracicregion, whereas an inferior vena caval-like pattern was themost frequent finding in the lumbar epidural space. Manoeuvresproducing a generalized increase of venous pressure raised theepidural pressure all along the spine. Manoeuvres raising thevenous pressure in the superior or in the inferior vena cavalsystem were accompanied by a preferential increase in the pressureof the cervical or in the lumbar epidural space. As a consequence,it is suggested that the epidural space, unlike the subarachnoidcompartment, presents some degree of functional compartmentalizationinto three zones: cervico-thoracic, lumbar and sacral. It ispostulated that changes in visceral cavity pressures can betransmitted to the epidural space directly, through the intervertebralforamina and indirectly via both vena cava and the cerebrospinalfluid. It is concluded that factors increasing intrathoracicor intra-abdominal pressures will raise epidural space pressureand, as a consequence, may favour the spread of anaestheticsinjected into the epidural space.     

Why promote breastfeeding in diarrhoeal disease control programmes?

The improvement of case management practices is the cornerstoneof national programmes to control childhood diarrhoea and canlead to a rapid reduction in diarrhoeal mortality. There is,however, increasing interest in the development of interventionsthat can reduce diarrhoeal morbidity, especially in countrieswhere case management activities are well established. The DiarrhoealDisease Control Programme of the World Health Organization recommendsthat breastfeeding be promoted as one of the most importantmeasures for preventing diarrhoea. There is now conclusive evidencethat breastfeeding confers significant protection against illnessand death associated with diarrhoea, and minimizes its adversenutritional effects. Breastfeeding promotion has been demonstratedto be an efficient measure for preventing diarrhoea, and hasmany other important social, economic and health benefits. Thispaper summarizes the evidence and describes the Programme'songoing and planned activities in support of efforts to promotebreastfeeding.     

Ambient Fluid Velocity Influences Proximal Isovelocity Surface Area Calculations

Background: Recent reports have described a simplified mass balance equation designed to predict volumetric flow rate through regurgitant and shunt orifices. The proximal isovelocity surface area (PISA) technique relies on the assumption that constant velocity surfaces (isovels) that are hemispheric in shape can be constructed proximal to the orifice, and flow passing through these surfaces must also pass through the orifice by conservation of mass. The method has been validated in simplified in vitro models, but these models have been symmetric in design and do not consist of ambient crossflows that are found in the beating heart. This study addressed the hypothesis that ambient crossflow will affect the validity of the PISA method. Methods and Results: An in vitro model was designed to test the effect of crossflowing streams on the PISA calculation while maintaining control of volumetric flow through the orifice. PISA predicted flows showed a good correlation but overestimated actual flows by 10%–110% (Y = 2.16X-118, r = 0.96). Addition of low flow data slightly reduced the overestimation (Y = 1.89X-55.2, r = 0.97). Only under high output state conditions (high orifice and crossing flows) was good agreement found (Y = 0.92X + 9.78, r = 0.95). Conclusions: The presence of crossflowing streams in the vicinity of PISA images will distort the converging flow and its image in such a way that the simplified PISA theory may correlate with true flow but only rarely produces true agreement. Only when competing factors fortuitously cancel does the PISA method appear to be accurate. Since PISA images are readily obtained in patients and since the method has received extensive attention in the literature, systematic derivation of correction factors accounting for crossflow is indicated. In the meantime, caution should be exercised when interpreting PISA images in the presence of crossflowing streams .     

Phenotypic Analysis of Resident Lymphoid Cells in the Conjunctiva and Adnexal Tissues of Rat

The conjunctival associated lymphoid tissue is considered to be an integral part of the mucosal immune system. Under normal circumstances immune mechanisms in mucosal associated lymphoid tissue of the gut and bronchus can selectively suppress, rather than enhance, immune responsiveness to encountered antigens, inducing a state of tolerance. It is possible that conjunctival associated lymphoid tissue can also induce a state of tolerance to encountered antigens. Such a response may be exploited to modulate immune mediated ocular disease. Enhanced tolerance may protect the host against foreign antigen. Alternatively, under certain circumstances when the normal immune system is altered or disrupted the mucosal tissue may act to induce sensitisation and trigger immune mediated disease.The rat is frequently used as an animal model of immune mediated eye disease, but the normal profile of immune cells in the rat conjunctiva has not been studied. This information is essential for meaningful interpretation in the experimental situation. In this study we examined the immunophenotype of lymphoid tissue associated with the conjunctiva, lacrimal gland and Harderian gland of the Lewis rat. CD4⁺, Ia⁺and the monocyte/macrophage population of cells were found predominantly in the substantia propria of the conjunctiva and interstitial connective tissue of the glands. CD8⁺cells were distributed mainly in relation to the conjunctival and glandular epithelium. Goblet cells stained strongly with the monoclonal antibody (MAb) MRC OX-39, which is a marker for IL-2 receptors. The overall pattern of distribution of immunocompetent cells in the rat was found to be similar to that reported in humans.