Influence of housing conditions on pregnancy outcome in cynomolgus monkeys (Macaca fascicularis).

Female cynomolgus monkeys (Macaca fascicularis) were kept under 3 different housing conditions: individually in type A cages (45 X 45 X 60 cm), individually in type B cages (70 X 70 X 100 cm) and as couples in type B cages. Primigravida did not show early embryonic mortality, differing significantly from 11.5% early losses in multigravida. Early embryonic mortality was not affected by housing condition. Further reproductive failure rates did not differ significantly for primigravid (18.5%) and multigravid females (24.0%), though abortion tended to occur more frequently in primigravida. Perinatal mortality (16.1%) accounted for most of the losses under each housing condition. More successful pregnancies (90%) were recorded for females housed individually in type B cages than for females housed in type A cages (68%). About 50% of the couples originally established remained until weaning of their infants, yielding 77% viable offspring. For multigravid females statistical evaluation showed a significant effect of housing conditions on reproductive outcome (X2-test 0.01 less than P less than 0.05) that could be entirely attributed to low losses in females housed individually in type B cages. It is concluded that housing conditions can have a profound influence on reproductive success in cynomolgus monkeys.

Comparison of radioimmunoassay and enzyme-linked immunosorbent assay in measurement of antibodies to Neisseria meningitidis group A capsular polysaccharide.

Antibodies to meningococcal group A polysaccharide were determined by radioimmunoassay (RIA) and enzyme-linked immunosorbent assay (ELISA) in serum samples from 16 adults vaccinated with bivalent meningococcal group A and C polysaccharide vaccine. The specific antibody levels in the serum samples were expressed as micrograms of antibody protein per milliliter of serum. For RIA the polysaccharide was radiolabeled extrinsically with 125I. Both native polysaccharide and polysaccharide labeled with 127I were used in ELISA. Because these antigens gave similar results, it can be concluded that the introduction of tyramine and iodine by the labeling procedure did not alter the antigenic activity of the polysaccharide. The reproducibility of RIA was clearly better than that of ELISA. The antibody levels detected by the methods were equal, which means that ELISA can be used satisfactorily to measure antibodies to meningococcal group A polysaccharide quantitatively. Some discrepant results were found due to an underestimation of immunoglobulin M antibodies in ELISA. This was shown by a correlation test in which a weakly significant negative correlation was found between the immunoglobulin M antibody level/immunoglobulin G antibody level ratio and the RIA antibody level/ELISA antibody level ratio.

Physicochemical and immunological characterization of meningococcal group A polysaccharide-tetanus toxoid conjugates prepared by two methods.

Two methods have been applied for the covalent binding of high molecular weight Neisseria meningitidis group A polysaccharide to tetanus toxoid. The first method used cyanogen bromide as the coupling reagent and the second used both glycine and 6-amino-n-hexanoic acid as spacers and N-ethyl-N'-(3-dimethylaminopropyl) carbodiimide as the coupling reagent. Each conjugation was performed twice. The conjugates were analysed by biochemical, physicochemical and immunochemical techniques. The immunogenic activities of the conjugates were studied in mice. The IgG responses to both components of the conjugates were measured by the enzyme-linked immunosorbent assay (ELISA). After the first dose differences in immunogenic activity of the tetanus toxoid component of the conjugates were seen, whereas after the second dose differences in activity of the polysaccharide component were observed. The second dose of all conjugates produced clear booster effects in the responses to both components. AlPO4 potentiated both the primary antibody responses and did not influence the booster effects. These data indicate that both components of the conjugates behaved as thymic-dependent immunogens. The second method of preparation resulted in conjugates with higher immunogenic activities. Significant differences in activity, however, were seen between conjugates prepared by the same method. These data indicate that the reproducibility of the method of preparation needs further consideration.

Preparation and physicochemical and immunological characterization of polysaccharide-outer membrane protein complexes of Neisseria meningitidis.

A crude complex containing group C polysaccharide, outer membrane proteins, and lipopolysaccharide (LPS) was isolated from the cell-free culture liquid of Neisseria meningitidis serogroup C, serotype 2a. Group C polysaccharide and LPS were removed from this complex, resulting in an outer membrane complex and a purified complex, respectively. Analysis by electron microscopy showed the outer membrane origin of the crude complex and the outer membrane complex, whereas such a structure was absent in the purified complex. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis patterns of the three complexes were identical. Pyrolysis-mass spectrometry data correlated well with those obtained by the biochemical assays and suggested a low LPS content in the purified complex and a low polysaccharide content in the outer membrane complex. The purified complex was shown to be nonpyrogenic and could be prepared with the same yield as that of purified polysaccharide. The immunogenic activities of the complexes were studied in mice. The antibodies were measured by the enzyme-linked immunosorbent assay; and the bactericidal antibody assay. All complexes induced immunoglobulin G antibodies to group C polysaccharide as well as to the serotype antigen, although the removal of polysaccharide and LPS resulted in a reduction of the immunogenic activities of outer membrane complex and purified complex, respectively. A second dose of all complexes produced a clear booster effect of both antibody responses. The antibodies were bactericidal.

Immunoglobulin M and G antibody responses and persistence of these antibodies in adults after vaccination with a combined meningococcal group A and group C polysaccharide vaccine.

Adult volunteers were injected with a combined meningococcal group A and group C polysaccharide vaccine. Immunoglobulin M (IgM) and IgG antibody levels against both polysaccharides were measured in serum samples taken 14 days as well as 3 years after vaccination. For both group A and group C polysaccharides, the IgM and IgG antibody levels at 14 days postvaccination were positively related. The IgM-to-IgG antibody ratio at 14 days postvaccination was an indicator for the persistence of both IgM and IgG antibodies during the next 3 years; a high ratio meant a short persistence, whereas a low ratio was associated with a long persistence.

The precision of clinical estriol and total estrogen estimations in pregnancy urine.

1. A study of the precision of clinical estriol- and total estrogen determinations in late pregnancy urine was carried out in collaboration with 26 clinical laboratories in the Netherlands and one laboratory in Suriname. 2. Ten urine samples were circulated twice with an interval of 2 weeks. 3. It was shown, that repeated analysis of the same sample in the same clinical laboratory in different assays can yield differences in results up to 40%. This interassay variation can be regarded as the main source of uncertainty of results of clinical estriol and total estrogen determinations. 4. The quantitative differences between results of total estrogen methods and a gas chromatographic method, which measures only estriol, were shown to be caused primarily by the lower recovery of the glucuronide of estriol (both native and added) in the latter method. 5. As expected, methods based on the principle of Ittrich (1960), Acta Endocrinol. 35, 34-48) proved to be more susceptible to the disturbing influence of glucose than a gas chromatographic method that measured estriol specifically. 6. Various recommendations to improve the precision of clinical estrogen determinations in pregnancy urine resulted from this study.