ManagementHandbuch für die psychotherapeutische Praxis – MHP.

Ohne Zusammenfassung     

Extensive cytocidal replication of lactate dehydrogenase-elevating virus in cultured peritoneal macrophages from 1-2-week-old mice

Indirect fluorescent antibody staining was used to examine the replication of lactate dehydrogenase-elevating virus (LDV) in primary cultures of peritoneal macrophages from BALB/c mice of different ages. Up to 80% of the total peritoneal macrophages from 1-2-week-old mice were susceptible to productive infection by LDV, though only 1-2% of the cells expressed detectable levels of IA antigen. The proportion of LDV-permissive peritoneal macrophages progressively decreased to 5-15% between 2 and 5 weeks of age of the mice. Macrophages from 9-day-old mice, when cultured in the presence of L cell conditioned medium, retained undiminished LDV permissiveness for at least 10 days in culture. The maximum proportion of LDV antigen-positive cells was detected between 8-10 h post infection of macrophages cultured from both 1-2-week-old and adult mice, concomitant with maximum LDV RNA synthesis. The LDV antigen positive macrophages disappeared between 12 and 48 h post infection. In cultures of macrophages from 9-10-day-old mice, the loss of infected cells was clearly due to cell killing, proving unequivocally that LDV replication is cytocidal. Disintegration of LDV-infected macrophages or phagocytosis of killed macrophages by surviving macrophages must be very sudden and complete since infected cells disappeared without the appearance of trypan blue-stainable cells in the culture. Ten cell lines established from macrophages of 2, 9, and 10-day-old mice all contained a small proportion of LDV-permissive cells (1-4%). Individual clones of one of the lines contained a similar small proportion of LDV-permissive cells.     

Polyclonal B cell activation of IgG2a and IgG2b production by infection of mice with lactate dehydrogenase-elevating virus is partly dependent on CD4+ lymphocytes

Concentrations of IgM and IgG isotypes were determined by capture ELISA in plasma of Swiss, BALB/c and C58/M mice. Plasma IgG isotype concentrations, especially of IgM, IgG1 and IgG2a, varied considerably between mouse strains, batches of mice of the same strain and individual mice and as a function of age. Infection of the mice with LDV, which is known to replicate primarily in a subpopulation of macrophages, consistently resulted in a rapid elevation of plasma IgG2a (or of IgG2b in some Swiss nu/+ mice), but no plasma IgG increases were observed in mice immunized with inactivated LDV. Plasma IgG2a elevation after LDV infection was greatly delayed and reduced by depletion of the mice of CD4+, but not of CD8+, T cells by administration of protein-G-purified anti-CD4 or anti-CD8 mAbs, and completely inhibited by repeated treatment of the mice with cyclophosphamide. Treatment with anti-CD4 mAbs, or cyclophosphamide also greatly reduced the production of anti-LDV antibodies, while not significantly affecting the replication of LDV in these mice. Nude Swiss mice also failed to produce anti-LDV antibodies, though supporting normal LDV replication. Plasma IgM, IgG1, IgG2a and IgG2b levels increased in LDV-infected nu/nu mice, but similar changes were observed in uninfected mice. The results indicate that the LDV-induced polyclonal activation of B cells requires productive LDV infection of mice and is, at least partly, dependent on functioning CD4+ cells. They suggest that productive infection of the LDV-permissive subpopulation of macrophages leads to the activation of CD4+ T lymphocytes of subset 1 and their Spleen cells from 5-day LDV-infected BALB/c mice incorporated [3H]thymidine 2-3 times more rapidly in vitro than spleen cells from companion uninfected mice, whereas their responses to concanavalin A and lipopolysaccharide were reduced 60-70%.     

Hydrophobic IgG-containing immune complexes in the plasma of autoimmune MRL/lpr mice, lactate dehydrogenase-elevating virus-infected mice, and pigs: association with transforming growth factor-beta and pH-dependent amplification

Persistent infection of mice with lactate dehydrogenase-elevating virus (LDV) is associated with polyclonal B cell activation, autoimmunity, and circulating hydrophobic IgG-containing immune complexes (ICs), which bind to the surfaces of uncoated ELISA plates in the presence of 0.05% Tween 20. We demonstrate here that hydrophobic IgG-containing ICs also appear naturally in the plasma of autoimmune MRL/lpr mice. These and the similar hydrophobic ICs of LDV-infected mice as well as pigs coincide on ELISA plate surfaces with TGF-beta, apparently in the form of an IgG-TGF-beta complex. Circulating hydrophobic IgG-containing ICs are also susceptible to considerable amplification in vitro by exposure to alkaline conditions. By this latter method, the fraction of in vivo hydrophobic IgG, relative to the maximum in vitro chemically inducible IgG, was found to be about 20% in the plasma of LDV-infected mice, 5% in normal mouse plasma, and less than about 2% in pig plasma. These results indicate the potential for both chemically induced and protein-binding contributions to the generation of hydrophobic IgG-containing molecules, and have implications for immunopathological mechanisms in autoimmunity and persistent virus infections.     

The primary neutralization epitope of porcine respiratory and reproductive syndrome virus strain VR-2332 is located in the middle of the GP5 ectodomain

Summary.  Pigs infected with porcine respiratory and reproductive syndrome virus (PRRSV) strain VR-2332 were found to generate high levels of antibodies (Abs) that bound in an indirect ELISA to synthetic peptides representing segments of the primary envelope glycoprotein (GP5) ectodomain of this virus. Use of overlapping GP5 ectodomain peptides of various length indicated that the epitope recognized by the Abs was located in the middle of the ectodomain (amino acids 36-52), in the same relative segment that contains the single linear neutralization epitope of the closely related mouse arterivirus, lactate dehydrogenase-elevating virus (LDV). The VR-2332 GP5 segment exhibits 77% amino acid homology with the corresponding GP5 ectodomain segments of both the European PRRSV strain Lelystad virus (LV) and LDV. This explains some observed crossreaction between the pig Abs and neutralizing anti-LDV monoclonal Abs with peptides representing the GP5 ectodomains of VR-2332, LV and LDV. The GP5 binding Abs of pigs seem to be the primary PRRSV neutralizing Abs, since the well timed appearance in sera of all VR-2332 infected pigs of GP5 peptide binding Abs correlated 100% with the appearance of neutralizing Abs and earlier studies indicated that GP5 of PRRSV, like that of other arteriviruses, contains the main neutralization epitope of PRRSV. In addition, one neutralizing anti-LDV monoclonal Ab that is specific for the GP5 ectodomain epitope of LDV also strongly neutralized both PRRSV strains, VR-2332 and LV. The PRRSV GP5 epitope is associated with an N-glycan that is conserved in both PRRSV genotypes and all LDV isolates. This N-glycan may impede the humoral immune control of PRRSV in infected pigs and might be responsible for the low immunogenicity of PRRSV when injected into mice. Received April 2, 2002; accepted July 9, 2002     

Elevation of hypothalamic neuropeptide Y-neurons in adult offspring of diabetic mother rats

We recently reported on an elevation of neurons expressing the main orexigenic peptide neuropeptide Y (NPY) in the arcuate hypothalamic nucleus (ARC) of neonatally hyperinsulinaemic offspring of gestational diabetic mother rats (GD) at weaning. To investigate possible consequences, the long-term outcome of those animals was examined. At adult age, GD offspring showed hyperphagia (p < 0.001), basal hyperinsulinaemia (p < 0.05) and impaired glucose tolerance (p < 0.05), and were overweight (p < 0.01). This was accompanied by an elevated number of NPY neurons (p < 0.001) and galanin neurons (p < 0.001) in the ARC in adult GD offspring under basal conditions. These findings support our hypothesis on perinatally acquired, persisting malformation and/or malprogramming of peptidergic hypothalamic neurons in the offspring of GD mothers, possibly promoting the development of overweight and diabetogenic disturbances during life.     

Duration of breastfeeding and risk of overweight: a meta-analysis

Observational studies suggest a longer duration of breastfeeding to be associated dose dependently with a decrease in risk of overweight in later life. The authors performed a comprehensive meta-analysis of the existing studies on duration of breastfeeding and risk of overweight. Studies were included that reported the odds ratio and 95% confidence interval (or the data to calculate them) of overweight associated with breastfeeding and that reported the duration of breastfeeding and used exclusively formula-fed subjects as the referent. Seventeen studies met the inclusion criteria. By meta-regression, the duration of breastfeeding was inversely associated with the risk of overweight (regression coefficient=0.94, 95% confidence interval (CI): 0.89, 0.98). Categorical analysis confirmed this dose-response association (<1 month of breastfeeding: odds ratio (OR)=1.0, 95% CI: 0.65, 1.55; 1-3 months: OR=0.81, 95% CI: 0.74, 0.88; 4-6 months: OR=0.76, 95% CI: 0.67, 0.86; 7-9 months: OR=0.67, 95% CI: 0.55, 0.82; >9 months: OR=0.68, 95% CI: 0.50, 0.91). One month of breastfeeding was associated with a 4% decrease in risk (OR=0.96/month of breastfeeding, 95% CI: 0.94, 0.98). The definitions of overweight and age had no influence. These findings strongly support a dose-dependent association between longer duration of breastfeeding and decrease in risk of overweight.