The early postnatal development of the primary immune response in TNP-KLH-stimulated popliteal lymph node in the rat

Summary The popliteal lymph nodes were removed from young rats of various ages five days after a single immunization with TNP-KLH in the hind footpads. Cryostat sections of the lymph nodes were investigated by means of enzyme and immunohistochemical techniques at the light-microscopical level.The presence and localization of anti-TNP antibody-containing cells were examined using a new technique to visualize specific antibodies. Moreover, the development of the lymph nodes following exogenous antigenic stimulation was compared with that of unstimulated lymph nodes.Specific antibody-containing cells could not be found before day 15 after birth, in rats immunized at day 10. From that time these lymphoid cells were located primarily at the border between cortex and medulla. Younger popliteal lymph nodes showed only aspecific immunoglobulin-containing lymphoid cells. With age, the number of specific antibody-containing cells tended to increase. These cells were more mature, according to morphological criteria and were located nearer the medulla.The first primary follicles were seen at day 19, as was the case in unstimulated animals. The first secondary follicles, containing germinal centers, were detected at day 23, whereas in unstimulated popliteal lymph nodes they were never found.Trapping of immune complexes could not be demonstrated before day 33 after birth. The later appearance of this phenomenon might be a consequence of the techniques applied to demonstrate specific antibody-containing cells.Abbreviations PLN popliteal lymph node - FDC follicular dendritic cell - IDC interdigitating cell - HEV high endothelial venule - TNP trinitrophenyl - KLH keyhole limpet hemocyanin - PBS phosphate-buffered saline - GCPC germinal center precursor cell - sIg surface immunoglobulin - cIg cytoplasmic immunoglobulin     

Severe Metabolic Acidemia in Infants: Clinical and Therapeutic Aspects

A study of 10 infants in severe metabolic acidemia (pH below 7) led to the conclusion that the clinical signs—hyperventilation, coma or lethargy, peripheral vascular collapse, a significantly palpable liver, and abdominal distension—may all be directly related to the metabolic acidemia. In five of 10 infants, an initial erroneous diagnosis of congestive heart failure or pneumonia was made. Dramatic clinical improvement followed correction of the acidemia with rapid intravenous administration of sodium bicarbonate. This rapid administration of sodium bicarbonate was safe, provided hypocalcemia was recognized and treated in its early stages. In severe metabolic acidemia the measurement of blood bicarbonate alone does not reflect adequately the magnitude of the acid-base derangement and repeated measurements of hydrogen ion concentration, Pco₂ and bicarbonates are needed to evaluate and treat such infants correctly.     

Classical plant taxonomic ambiguities extend to the molecular level

Summary The molecular evolution of cytochrome c from angiosperms is compared to that from vertebrates. On the basis of a cladistic analysis from 26 plant species, compared to that from 27 vertebrate species, we find that although the vertebrate sequences yield reasonably well-defined minimal trees that are congruent with the biological tree, the plant sequences yield multiple minimal trees that are not only highly incongruent with each other, but none of which is congruent with any reasonably biological tree. That is, the plant sequence set is much more homoplastic than that of the animal. However, as judged by the relative rate test, the extent of divergence, and degree of functional constraint, cytochrome c evolution in plants does not appear to differ from that of vertebrates.     

Influence of oestradiol on protein expression and methionine utilization during morphogenesis of Paracoccidioides brasiliensis

The temporal sequence of cytosolic protein expression during phase transition of Paracoccidioides brasiliensis was examined. Electrophoretic analysis of cytosol proteins by one-dimensional SDS-PAGE revealed numerous differences between the mycelial and yeast forms as well as alterations induced by 17 beta-oestradiol. Using either protein staining or fluorography of [35S]methionine-labelled proteins 30 phase-specific bands were detected, 12 mycelial-associated bands (range 30 to 140 kDa) and 18 yeast-associated bands (range 22 to 127 kDa). In cells undergoing mycelial to yeast transition after a shift from 25 degrees C to 37 degrees C, the protein patterns showed a temporal progression toward the yeast profile with the accumulation of yeast bands prior to observable morphogenesis. Five novel protein bands (range 23 to 50 kDa) were detected by silver staining during transition. Treatment of temperature-shifted mycelial cultures with 2.6 x 10(-7) M-oestradiol altered observed profiles; 4 of 12 mycelial-associated bands were maintained whereas the appearance of the 5 novel transition bands and 9 of 18 yeast-associated bands was blocked or delayed. Analysis of [35S]methionine-labelled proteins revealed that oestradiol induced label uptake by mycelial cells, blocked the synthesis of a 92 kDa yeast-specific band 72 h into transition, and diminished label incorporation 120 h into transition. In conjunction with these steroid-induced alterations of protein expression, little or no morphological transformation occurred. These results support our hypothesis that, analogous to mammalian steroid receptor action, the functional responses of P. brasiliensis to oestradiol are related to regulation of protein expression, presumably mediated via a specific binding protein-ligand complex.     

Modulation of antibody-mediated glomerular injury in vivo by bacterial lipopolysaccharide, tumor necrosis factor, and IL-1

We have investigated the effects of LPS, human rTNF (hrTNF) and human rIL-1 beta (hrIL-1 beta) pretreatment on the intensity of antibody-mediated injury in vivo by using a passive model of anti-glomerular basement membrane (GBM) antibody-mediated nephritis in rats. The experiments show that all three pretreatments exacerbate injury in this model whether judged by albuminuria or the prevalence of glomerular capillary thrombi. The effect on albuminuria was dose dependent with all three treatments. The lowest effective dose of LPS was 0.025 microgram while those for hrTNF and hrIL-1 beta were 0.4 microgram and 0.5 microgram, respectively. All three pretreatments also increased the prevalence of glomerular capillary thrombi which were rare in rats injected with anti-GBM antibodies without pretreatment. LPS pretreatment appeared to be more effective in causing glomerular capillary thrombi than hrTNF or hrIL-1 beta and this was reflected in the correlations between albuminuria and the proportion of glomeruli with capillary thrombi. This relation was linear for all three pretreatments but the slope was appreciably greater for rats pretreated with LPS (0.37) when compared with results from rats given either hrTNF (0.22) or hrIL-1 beta (0.29). Pretreatment of nephritic rats with both cytokines increased the slope to 0.42 demonstrating a synergistic effect. The synergism of hrTNF with hrIL-1 beta was also demonstrated by the effective doses needed to induce albuminuria which was evident in rats treated with 0.05 microgram of IL-1 beta and 0.4 microgram of TNF. Neither the cytokines nor LPS caused clinical, morphologic, or biochemical evidence of renal toxicity when given alone in the dose used here but they did cause a transient increase in the number of neutrophils marginated in glomerular capillaries. Pretreatment of rats with LPS or cytokines increased the glomerular neutrophil influx after anti-GBM antibodies by roughly sixfold. Our experiments show that TNF and IL-1 can increase the severity of glomerular injury in nephritis; they may be important in modulating glomerular injury clinically.     

Genotype-specific response of cultured broccoli (Brassica oleracea var. italica) anthers to cytokinins

Anther culture medium was prepared with different types and concentrations of cytokinins to gain greater insight into the control of embryo formation during Brassica oleracea L. var. italica (broccoli) anther culture. The independent addition of the four cytokinins tested had widely divergent effects dependent upon cytokinin concentration and the genetic background of the test plants. All cytokinins were generally inhibitory at high concentrations, however, individual plants showed significant stimulation of embyro formation at typical physiological levels. The influence of cytokinins was highly cultivar-specific, some lines were stimulated, others inhibited and still other test lines were largely unaffected. Although the addition of cytokinins was needed for embryo formation for some plants, in no instance were cytokinins able to replace the inductive effect of high-temperature treatments.