Platelet interactions with viruses and parasites

Abstract

While the interactions between Gram-positive bacteria and platelets have been well characterized, there is a paucity of data on the interaction between other pathogens and platelets. However, thrombocytopenia is a common feature with many infections especially viral hemorrhagic fever. The little available data on these interactions indicate a similarity with bacteria-platelet interactions with receptors such as FcγRIIa and Toll-Like Receptors (TLR) playing key roles with many pathogens. This review summarizes the known interactions between platelets and pathogens such as viruses, fungi and parasites.     

Partial Portal Vein Ligation Plus Thioacetamide: A Method to Obtain a New Model of Cirrhosis and Chronic Portal Hypertension in the Rat

To obtain a new model of chronic portal hypertension in the rat, two classical methods to produce portal hypertension, partial portal vein ligation and the oral administration of thioacetamide (TAA), have been combined. Male Wistar rats were divided into four groups: 1 (control; n?=?10), 2 [triple partial portal vein ligation (TPVL); n?=?9], 3 (TAA; n?=?11), and 4 (TPVL plus TAA; n?=?9). After 3 months, portal pressure, types of portosystemic collateral circulation, laboratory hepatic function tests (aspartate aminotransferase, alanine aminotransferase, bilirubin, alkaline phosphatase, and gamma-glutamyl transpeptidase) and liver histology were studied. The animals belonging to group 2 (TPVL) developed extrahepatic portosystemic collateral circulation, associated with mesenteric venous vasculopathy without hepatic destructurization or portal hypertension. Animals from group 3 (TAA) developed cirrhosis and portal hypertension but not extrahepatic portosystemic collateral circulation, or mesenteric venous vasculopathy. Finally, the animals from group 4 (TPVL?+?TAA) developed cirrhosis, portal hypertension, portosystemic collateral circulation, and mesenteric venous vasculopathy. The association of TPVL and TAA can be used to obtain a model of chronic portal hypertension in the rat that includes all the alterations that patients with hepatic cirrhosis usually have. This could, therefore, prove to be a useful tool to study the pathophysiological mechanisms involved in these alterations.     

The nurse's work in the care plan for families in the mountains

In this investigation is demonstrated that the nurse needs, in order to carry out a successful work, to learn about the composition of the population of the area under her care. In Patana, a Maisí municipality with 165 inhabitants, 93 male and 72 females, prevailing ninth grade school level and an initial low hygienic culture level, which is considered as regular at the present time, intestinal parasitism and malnutrition are the main diseases in the zone. It is well demonstrated that there is a wide relationship between hygienic conditions at home and community and the incidence of the fore-mentioned diseases and that the educational work performed by the nurse in the area under her care exerts a positive influence, but the support of grassroot mass organizations is required.     

Non-linear tissue binding of amikacin in rats: the effect of renal impairment

Amikacin levels in serum and tissues were determined in 115 Wistar rats, 70 with normal renal function (NRF) and the remaining 45 with terminal renal impairment (TRI). The results obtained in the animals with NRF show an accumulation of the antibiotic in all the tissues studied as compared with plasma levels, specially in the renal cortex and medulla. In the rats with TRI important alterations in the plasma and tissue kinetics of the antibiotics were observed. The plasma kinetics of amikacin in rats with TRI are characterised by significant alterations in the pharmacokinetic parameters, specially those defining the distribution processes of the antibiotic. In the tissues of the latter, a significant increase in the antibiotic concentration takes place, particularly in the renal cortex. The average half-lives of the antibiotic in the tissues of rats with TRI increase compared with the group of rats with NRF, though the difference are not so significant as in the case of the plasma half-life. The use of a specific kinetic distribution model, with linear and non-linear tissue binding, showed that significant variations occur in the partition coefficient and in the Michaelis-Menten parameters, which characterize the saturable binding of Amikacin to tissue in rats with NRF and TRI.     

Parvalbumin immunoreactive neurons and fibres in the teleost cerebellum

Summary The distribution of parvalbumin-(PV) immunopositive cell bodies and fibres in the cerebellum of two species of freshwater teleosts (Salmo gairdneri and Barbus meridonalis) was studied using a monoclonal antibody and the avidin-biotin immunoperoxidase technique. A clear laminated pattern of PV immunoreactivity was observed. After PV-immunostaining, Purkinje cells were strongly labelled in their cell bodies, the initial segments of the axons and the dendritic trees. In the molecular layer, only the dendritic branches of the Purkinje cells were PV-positive. In the granule cell layer, extensive axonal plexuses and scattered cell bodies were observed. Most of the immunopositive perikarya were unequivocally identified as displaced Purkinje cells, whereas a reduced number of smaller neurons with unstained dendrites was also found. Eurydendroid cells, the efferent neurons of the teleost cerebellum, were negative; however, they were impinged upon by numerous PV-positive boutons, corresponding to terminals of Purkinje cell axons. Parallel fibres and climbing fibres, as well as stellate cells and granule cells were negative. Basket cells (or deep stellate cells) whose existence in the teleost cerebellum is discussed, were also not observed. The immunoreactivity distribution pattern for PV in the teleost cerebellum differs from previous observations on the localization of this protein in the cerebellum of amniotes.     

Down-regulation of murine B lymphocyte growth: arrest of B cells in G1 underlies immunosuppression induced by an IgM antibody.

Previous studies have demonstrated that culture supernatants of LPS-stimulated murine splenic B lymphocytes (BLPSSN) are able to inhibit the growth of freshly isolated B cells via an IgM antibody. In this work we investigated the progress of LPS-activated B lymphocytes through the cell cycle in the presence of this antibody. We found that the regulatory IgM did not affect the entry of LPS-stimulated B lymphocytes into G0*, as assessed by the increased expression of I-A antigens. Events that characterize the early G1 phase (G1A), such as cell enlargement and increased RNA synthesis, also occurred in the presence of the antibody. In contrast, events which mark the G1B phase, such as further cell enlargement and late RNA synthesis were inhibited. Moreover, a significant portion of the cells failed to incorporate [3H]thymidine and did not progress through S, G2, or M, as revealed by their DNA content. Therefore, our work points toward a well-defined stage of the early G1 phase at which the antibody inhibits the progression of B lymphocyte activation. This result shows a new insight into the mechanism of antibody-mediated down-regulation of polyclonal B cell responses.     

Usefulness of antiendomysial antibodies as a serological marker in coeliac children

The new diagnostic criteria of coeliac disease (CD) give more importance to serological markers. Immunoglobulin A antiendomysial antibodies (IgA-EmA) were determined in 138 sera from 79 coeliac children and the antibody levels compared to IgG and IgA antigliadin antibodies (IgG-AGA, IgA-AGA) in the sera. The assessment was also carried out in 29 children with other gastrointestinal diseases, 29 with non-gastrointestinal diseases and 35 healthy children. The IgA-EmA had a 91.4% specificity and a 88.4% sensitivity for active CD. The corresponding figures were 89.8% and 64.4% for IgA-AGA and 73.7% and 86.2% for IgG-AGA, respectively. The results of IgA-EmA determinations were concordant with the intestinal biopsy findings in 90% of cases, versus 80% for IgA-AGA and 83% for IgG-AGA. In most of the discordant cases the biopsy showed only minor changes, making the classification difficult. All patients with positive IgA₂-EmA also had positive IgA₁ EmA antibodies. IgA-EmA are an excellent serological marker of CD activity in children and they are useful to decrease the number of intestinal biopsies which are needed to confirm the diagnosis in coeliac patients.     

Distribution of calbindin D-28K and parvalbumin immunoreactivities in the nucleus olfactorius anterior of the rat

The distributions of calbindin D-28K (CaBP) and parvalbumin (PV) in the rat nucleus olfactorius anterior (NOA) were described using monoclonal antibodies and the avidin-biotin-peroxidase method. The NOA showed a high immunoreactivity for CaBP, with a rostrocaudal increase in the positive neurons and fibres. Pars externa (NOAe) was the only subdivision which showed a low CaBP immunostaining. PV-positive elements were less abundant than those CaBP immunostained. The main difference in the distributions for both proteins was observed in the pars medialis which was practically PV negative. PV- and CaBP-stained neurons showed similar morphologies in the subdivisions where they were present. In NOAe, we observed a characteristic PV- and CaBP-positive neuronal type, with an oriented dendritic pattern. Transition areas were clearly observable in both CaBP- and PV-labelled sections.     

Inmunoferon (Am3) Enhances the Activities of Early-Type Interferon Inducers and Natural Killer Cells.

The “in vivo” effect of Inmunoferon (AM3) on the production of interferon (IFN) and natural killer (NK) activity in young and old mice was studied. Although AM3 is not an IFN inducer by itself, enhancements in the serum IFN levels were produced when drug was associated to Newcastle disease virus or bacterial lipopo-lysaccharides as IFN inducers. This effect appeared to be dependent on the time lapsed between the inducer agent and drug. In addition, a significant stimulating effect on NK cell activity was also produced by AM3 treatments. This effect could be a consequence of a marked IFN induction and/or a modifying effect in prostaglandin synthesis.