Passive immunization protects guinea pigs from lethal toxoplasma infection

Abstract The cellular and humoral interactions that contribute to protective immunity in toxoplasmosis were studied by adoptive transfer of selective cell populations or immune serum and its fractions into normal syngeneic strain 2 guinea pigs. The results of this study with the RH strain of Toxoplasma gondii confirm and extend the findings of previous studies by showing that the passive transfer of parasite-sensitized T cells or of immune serum from previously infected donors protected recipient guinea pigs against lethal toxoplasmosis. An additional key finding was that similar levels of complete protection against lethal infection occurred in guinea pigs receiving partially purified anti- Toxoplasma immunoglobulins or immune cells that had been enriched for B cells prior to transfer. Cells residing in the spleen, lymph nodes and peritoneal cavity, but not the thymus, were equally effective in conferring immunity to challenged recipients. In addition, cell titration experiments revealed that guinea pigs could survive T. gondii infection by infusing them with as little as 2 × 10⁷ sensitized T cells or B cells. Unlike protection mediated by T cells, protection against lethal disease occurring in the B cell recipients was associated with the formation of Toxoplasma antibodies. These findings illustrate the major role of both humoral and cell-mediated immunity in affording protection against toxoplasmosis based on a guinea pig model of the human disease.     

Enzyme-linked immunosorbent assays for detecting antibodies to Shiga-like toxin I,Shiga-like toxin II,andEscherichia coli O157:H7 lipopolysaccharide in human serum

Shiga-like toxin-producingEscherichia coli O157:H7 are important causes of bloody diarrhea and hemolytic uremic syndrome. To facilitate the epidemiologic study of these organisms, we developed enzyme-linked immunosorbent assays (ELISAs) for antibodies to Shiga-like toxin I (SLT I), Shiga-like toxin II (SLT II), andE. coli O157 lipopolysaccharide (LPS). We tested serum samples from 83 patients in two outbreaks ofE. coli O157:H7 diarrhea and from 66 well persons. Forty-three patients (52%) had at least one serum sample positive for anti-O157 LPS antibodies; among 26 culture-confirmed patients, 24 (92%) had at least one positive serum sample. Two (3%) of 66 control sera had positive anti-O157 LPS titers. ELISA results for SLT I and II were compared with those of HeLa cell cytotoxicity neutralization assays on both patient and control sera. Neutralization assays detected anti-SLT I antibodies in at least one serum sample from each of 17 (20%) patients and 7 (10.6%) controls, while 16 (19%) patients and 7 controls had positive titers by anti-SLT I ELISA. Although all serum samples, including control sera, showed nonspecific neutralization of SLT II, no antibody titers to SLT II were detected by either neutralization or ELISA. These results indicate that ELISAs for SLT I and SLT II antibodies are comparable to HeLa cell cytotoxicity neutralization assays. Both the ELISAs and neutralization assays are insensitive in detecting infected patients. However, the ELISA for antibodies toE. coli O157 LPS is both sensitive and specific, and may be more useful than assays for antitoxic antibodies in detecting persons withE. coli O157:H7 infection.     

Glycosylation of the human erythrocyte glucose transporter is essential for glucose transport activity

The human erythrocyte glucose transporter is a fully integrated membrane glycoprotein having only one N-linked carbohydrate chain on the extracellular part of the molecule. Several authors have suggested the involvement of the carbohydrate moiety in glucose transport, but not definitive results have been published to date. Using transport glycoproteins reconstituted in proteoliposomes, kinetic studies of zero-trans influx were performed before and after N-glycanase treatment of the proteoliposomes: this enzymatic treatment results in a 50% decrease of the Vmax. The orientation of transport glycoproteins in the lipid bilayer of liposomes was investigated and it appears that about half of the reconstituted transporter molecules are oriented properly. Finally, it could be concluded that the release of the carbohydrate moiety from the transport glycoproteins leads to the loss of their transport activity.     

Antiviral Activities of β-Enantiomers of 3′-Substituted-3′-deoxythymidine Analogs

Abstract

Several β-L-3′-substituted-3′-deoxythymidine were stereospecifically synthesized. None of these analogs inhibited HIV-1 nor HBV replication in vitro suggesting that these β-L-pyrimidine derivatives may not be efficiently phosphorylated inside the cells.     

A new small mammal assemblage from the M013 Terre Rosse fissure filling (Gargano,South-Eastern Italy)

The taxonomic study of the small mammal assemblage from fissure M013, sampled by a team of the University of Torino during the 2005–2009 excavations in the Dell’Erba Quarry (Apricena, Foggia) is presented. The assemblage includes the Echinosoricinae Apulogalerix cf. pusillus and the Crocidosoricinae ?Lartetium cf. dehmi; the Myomiminae species Stertomys simplex and Stertomys lyrifer; a new genus and species of Cricetodontinae and a single specimen of Hattomys cf. nazarii. Muridae include Mikrotia cf. parva, Mikrotia sp. 1 and a new genus and species of Murinae, phylogenetically related to Mikrotia. The occurrence of the new Murinae, the new Cricetodontinae, the two species of glirids and the Crocidosoricinae, as well as the absence of Apodemus and Prolagus, indicates M013 as the oldest Gargano's faunal assemblage known to date, despite the occurrence of Hattomys cf. nazarii, Mikrotia cf. parva and Mikrotia sp. 1, which most probably results from infiltrations from younger fissure fillings. The M013 assemblage is an absolute novelty for the Abruzzo-Apulian Palaeobioprovince, opening new perspectives for the timing and mode of dispersal of the forerunners of the Gargano fauna.     

Stimulation of Neuropeptide Y Overflow in the Rat Paraventricular Nucleus by Corticotropin-Releasing Factor

Abstract: Neuropeptide Y (NPY) and corticotropin-releasing factor (CRF) are present at high concentrations in the hypothalamus where they mediate important endocrine and autonomic functions. Morphological and physiological studies have suggested an interaction between these peptides, and opposing actions of CRF and NPY have been reported on feeding and other behaviors. This study investigated the effect of CRF on NPY release in vivo, measured by push-pull techniques, in the anesthetized rat. Push-pull probes implanted into the paraventricular nucleus of the hypothalamus (PVN) were perfused with modified Ringer solution containing bovine serum albumin at 15 µl/min, and the perfusate was lyophilized prior to NPY radioimmunoassay. NPY overflow from the rat PVN was increased threefold by perfusion of a depolarizing concentration of potassium (50 mmol/L KCI). When CRF was administered into the PVN via the push-pull cannula at 1 or 5 µg/ml, dose-dependent increases in NPY overflow of two- and fivefold were observed ( p < 0.05). These increases were abolished by prior intracerebroventricular (i.c.v.) administration of the CRF antagonist [ d -Phe¹²,Nle^21,38,C^αMeLeu³²]CRF (12–41) at 1 or 5 µg/µl, respectively. NPY overflow returned promptly to resting levels following CRF administration. In contrast, when CRF was administered by i.c.v. bolus at a similar total dose (2 µg), no significant effect on NPY overflow was observed. These data provide in vivo evidence for an interaction between CRF and NPY at the level of the PVN.