Characterization of T-cell immune responses of Echinococcus multilocularis-infected C57BL/6J mice

Specific and non-specific parasite-induced changes in lymphocyte responses were analysed in C57BL/6J mice after intrahepatic infection with Echinococcus multilocularis. Spleen cells harvested at selected times after infection were in vitro stimulated with mitogens or a crude soluble parasitic extract (EmAg) at an optimized dose. Cell proliferative responses to Con-A were not modified by the infection over the first 22 weeks. In contrast, LPS-induced responses were decreased from the 13th week. A strong CD4 ⁺ proliferative T-cell response to the parasitic extract of infected mouse spleen cells was observed at the early stage of infection. This response then progressively decreased but remained significantly higher than that of control mice until the 19th week of infection. Cytokine production was investigated after in vitro EmAg stimulation of spleen cells. IFN-γ, IL-2. IL-5 were produced within the first weeks after infection whereas the detection of IL-10 was slightly delayed. Thus, the promotion of the disease does not appear associated with the expansion of one rather than another T-cell subset in C57BL/6J mice. A general immunosuppression affecting both mitogenic and parasite-specific T-cell responses was observed at the end of the infection.     

Protection by Zinc-Metallothionein (ZnMT) against Cadmium-Metallothionein-Induced Nephrotoxicity

In contrast to inorganic Cd, acute iv administration of Cd boundto metallothionein (CdMT) concentrates in renal tissue. Thisuptake of CdMT produces functional and morphological changesin kidneys, similar to those observed after chronic exposureto inorganic Cd. In order to examine the importance of the metalcomponent of MT in the renal uptake of MT, the renal concentrationof ³⁵S after administration of [³⁵S]ZnMT and [³⁵S]CdMT was compared.Renal uptake of ³⁵S from both CdMT and ZnMT was very rapid,with peak concentrations observed 15–30 min after administration.³⁵S in kidneys increased in a dose-dependent manner after administrationof various doses of [³⁵S]ZnMT, up to 1.3 µmole MT/kg;however, higher doses did not further increase renal ³⁵S concentrations.A similar saturation of ³⁵S reabsorption was observed for therenal uptake of [³⁵S]CdMT. CdMT produced renal injury with dosesas low as 0.26 µmol MT/kg (0.2 mg Cd/kg). In contrast,with a dose of ZnMT as high as 5.12 µmol MT/kg (2 mg Zn/kg),no histopathological changes were observed. Therefore, ZnMTappears to be nontoxic even though ZnMT delivers more MT tothe kidney than does CdMT. Because ZnMT and CdMT are apparentlyhandled by the same renal transport mechanism, the effects ofZnMT on ¹⁰⁹CdMT renal uptake and nephrotoxicity were determined.One group of mice was given a nephrotoxic dose of ¹⁰⁹CdMT (0.51µmol MT/kg containing 0.4 mg Cd/kg, iv), and the othergroup received an equimolar dose of unlabeled ZnMT 1 min before¹⁰⁹CdMT administration. Renal function was evaluated by measuringurinary glucose and protein excretion, as well as histopathology.Marked renal toxicity was observed 24 hr after ¹⁰⁹CdMT administration.In contrast, renal function appeared normal in mice receivingZnMT before ¹⁰⁹CdMT. However, a similar concentration of ¹⁰⁹Cdwas found in kidneys of both groups. The present results demonstratethat ZnMT is not only nontoxic to the kidney at a dose as highas 5 µmol MT/kg, but can also protect against the nephrotoxiceffect of CdMT without decreasing renal Cd concentration.     

The Doctor and His Feelings: A Course for Residents in Family Medicine

A course on the doctor and his feelings was presented as partof a programme for family medicine residents. The course wasled by family physicians and behavioural science professionalswho taught as an integrated team. Various teaching techniqueswere utilized to highlight emotional aspects of the doctor-patientrelationship to inexperienced residents. Pre- and post-courseassessments suggested there were benefits in a short intensivecourse of this nature. Possible explanations for the findingsare discussed.     

Trypanosoma cruzi variants with reduced virulence obtained by mutagenesis

Summary Previous reports have indicated that by mutagen treatment of mouse tumour cells in vitro it is possible to obtain at high frequency stable tumour cell variants that fail to form tumours in syngeneic mice because of increased immunogenicity. By analogy with these tumour cell variants, we examined whether variants with reduced virulence could be obtained by mutagen treatment of trypomastigotes derived from a Trypanosoma cruzi strain that was adapted to culture and produced lethal infections in DBA/2 mice at a dose of 5 × 10⁴ parasites. A very large frequency of T. cruzi clones were obtained that failed to provoke an acute lethal infection after injection of 5 × 10⁵ parasites. Most of these variants with reduced virulence (vir^-) multiplied actively in normal mice until day 8 after injection. After that time the parasitaemia decreased gradually. For most variants a low level of residual parasitaemia persisted for more than 100 days. Unlike the situation encountered with mouse tumour cell variants it was not possible to demonstrate the presence of new antigens on the T. cruzi vir^- variants. However, these variants seemed to have acquired an increased immunogenicity since they provoked the rejection of virulent parasites injected concomitantly. Mice that had been immunized with living vir^- clones were protected against a challenge with a virulent clone derived from the original parasite population.     

Intestinal and systemic humoral immunological events in the susceptible Balb/C mouse strain after oral administration of Echinococcus multilocularis eggs

The aim of the study was to investigate the systemic and, for the first time, the intestinal humoral events in the susceptible Balb/C mouse strain after oral administration of Echinococcus multilocularis eggs. Thirty-one mice were divided into three groups; W-2 , W-8 and control group. Each mouse of the W-2 and W-8 groups was orally infected with 1,500 E. multilocularis eggs, two weeks and eight weeks before sacrifice respectively. Control group mice received phosphate buffer saline. Measurement of anti- E. multilocularis and non-specific IgG, IgA and IgM, and of a transudation marker, albumin, were performed in serum and intestinal washings by a time-resolved immunofluorometric assay. These results were complemented by microscopic examination of the intestinal mucosa. This infection model is well-suited to the study of mucosal immunity during alveolar echinococcosis. It showed a major specific intestinal response in the early stage of the disease whereas the systemic response predominated later in the disease. Histopathological studies and calculation of the relative coefficient of excretion of Ig also confirmed that the presence of the parasite, even during a short period, was responsible for a local immunological and inflammatory response and for a change in mucosal permeability. Mucosal immunity could thus play a role in tolerance induction against E. multilocularis that could be a prerequisite for the subsequent development of the larvae in the liver, and for the occurrence of the parasitic disease, alveolar echinococcosis .     

The Th1 to Th2 shift induced by Schistosoma mansoni does not exacerbate murine aids (MAIDS)

Schistosoma mansoni infection in mice is associated with a switch from a Th1 to a Th2-type cytokine response. The role of Th1 and Th2 responses in immune dysregulations associated with AIDS and murine AIDS (MAIDS) is controversial, but a Th2 bias could be associated with disease progression, raising the hypothesis that helminth infections might accelerate the retroviral disease progression. Here, we used the murine model of AIDS to evaluate the course of the viral disease during co-infection with S. mansoni . C57BL/6 mice were infected with S. mansoni cercariae 8 weeks before intravenous challenge with the LP-BM5 retroviral complex. MAIDS did not progress faster in co-infected mice, in terms of spleen and inguinal lymphadenopathy size, ecotropic virus titres in the spleen, or in vitro proliferative responses to mitogen. Th2 cytokine production was not enhanced in co-infected animals, except for an isolated increase in IL-4 production 21 weeks after LP-BM5 infection. Co-infected animals had significantly lower lymph node and spleen weights than mice infected with LP-BM5 only. MAIDS did not influence the granulomatous response to S. mansoni in the liver of co-infected mice. Finally, infection with S. mansoni neither enhanced Th2 cytokine production nor accelerated MAIDS progression in animals subsequently challenged with LP-BM5 .     

Defibrillation Energy Requirements Differ Between Anesthetic Agents

We examined the effect of anesthesia on the energy requirements for internal defibrillation (DF) in dogs anesthetized with pentobarbital (30 mg/kg IV followed by 2–3 mg/kg/hr constant infusion) (n = 20), fentanyl (25 μg/kg/hour) (n = 25), and enflurane (0.5%–1.5%) (n = 8). Multiple shocks of varying energies were applied through left and right ventricular epicardial patch electrodes to relate delivered energy to percent success in DF. The energies required for 50% success (E₅₀) and 80% success (E₈₀) in DF were estimated using logistic regression. E₅₀ in fentanyl anesthetized animals (3.8 ± 2.3 J) was significantly lower than in those given pentobarbital (6.9 ± 3.0 J) (P < 0.01), and lawer than those given enflurane (5.7 ± 2.8 J) (NS). E₈₀ with fentanyl (6.5 ± 4.0 J) was also lower than that of pentobarbital (10.4 ± 4.9 J) (P < 0.01) and enflurane (7.6 ± 4.3 J) (NS) animals. lawer defibrillation energy requirements (DER) with fentanyl anesthesia, when compared with pentobarbital, were associated with significantly longer ventricular effective refractory periods (VERP) (171 ± 20 versus 142 ± 15 msec: P < 0.01), lower mean arterial pressures (114 ± 20 vs 136 ± 25 mmHg: P < 0.01), and Iower heart rates (90 ± 37 versus 164 ± 19 b/m; P < 0.01).
Anesthetic agents may modify DER; their effects need to be taken into account in the assessment of DER in patients receiving implanted defibrillators and in the evaluation of the results of defibrillation research in anesthetized animals.     

Metabolic activity of human polymorphonuclear leucocytes: relation to ingestion rate

The ingestion rate and oxygen-dependent metabolic activities of normal human polymorphonuclear leucocytes were measured with heat-killed Klebsiella as the particle. Since the experimental conditions were similar for each measurement, it was possible to make direct correlations between each oxygen-dependent reaction and (1) ingestion rate and (2) the other oxygen-dependent reactions. In the controls, oxygen-uptake was more reliably correlated (r = 0.960) with ingestion rates than with (in order of reliability) hydrogen peroxide produced (r = 0.860) and iodination (r = 0.858 and 0.813 for 100 and 20 micromol/l iodide respectively). Hydrogen peroxide production (r = 0.988), nitroblue tetrazolium reduction (r = 0.969) and cytochrome c reduction (r = 0.862) were more reliably correlated to oxygen-uptake than to ingestion rate, and iodination was better related to hydrogen peroxide production (r = 0.90 and 0.819 for 100 and 20 micromol/l iodide respectively) than to ingestion rate. From these findings it was possible to locate primary defects in abnormal polymorphonuclear leucocytes from individual patients with pyogenic infections, idiopathic refractory anaemia or idiopathic oesteomyelofibrosis with splenomegaly, even when several deficiencies existed.