Ultrastructural localization of intracellular immunoglobulins in Epon-embedded human lymph nodes. An immunoelectron microscopic investigation using the immunogold staining (IGS) and the avidin-biotin-peroxidase complex (ABC) methods

The ultrastructural localization of intracellular immunoglobulins on ultrathin sections of glutaraldehyde-fixed, postosmicated, and Epon-embedded human lymph nodes has been achieved using such highly sensitive immunocytochemical techniques as immunogold staining and avidin-biotin-peroxidase complex. These immunoelectron microscopic techniques allow the identification of intracellular immunoglobulins without affecting the ultrastructural morphology of the tissue, since they do not require any pretreatment of the sections with proteolytic enzymes or deresinating agents. Therefore, immunoglobulins can be precisely localized in the cell organelles; structures whose morphology is well preserved. The availability of a reliable postembedding staining procedure for the ultrastructural localization of immunoglobulins is of definite value for investigations on human lymphoid tissue, both normal and pathological.     

Iron deficiency differently affects metabolic responses in soybean roots

Iron deficiency responses were investigated in roots of soybean, a Strategy I plant species. Soybean responds to iron deficiency by decreasing growth, both at the root and shoot level. Chlorotic symptoms in younger leaves were evident after a few days of iron deficiency, with chlorophyll content being dramatically decreased. Moreover, several important differences were found as compared with other species belonging to the same Strategy I. The main differences are (i) a lower capacity to acidify the hydroponic culture medium, that was also reflected by a lower H(+)-ATPase activity as determined in a plasma membrane-enriched fraction isolated from the roots; (ii) a drastically reduced activity of the phosphoenolpyruvate carboxylase enzyme; (iii) a decrease in both cytosolic and vacuolar pHs; (iv) an increase in the vacuolar phosphate concentration, and (v) an increased exudation of organic carbon, particularly citrate, phenolics, and amino acids. Apparently, in soybean roots, some of the responses to iron deficiency, such as the acidification of the rhizosphere and other related processes, do not occur or occur only at a lower degree. These results suggest that the biochemical mechanisms induced by this nutritional disorder are differently regulated in this plant. A possible role of inorganic phosphate in the balance of intracellular pHs is also discussed.     

Differences in the organization and chromosomal allocation of satellite DNA between the European long tailed house miceMus domesticus andMus musculus

We compared the organization of satellite DNA (stDNA) and its chromosomal allocation inMus domesticus and inMus musculus. The two stDNAs show similar restriction fragment profiles after digestion (probed withM. domesticus stDNA) with some endonucleases of which restriction sequences are present in the 230–240 bp repetitive unit of theM. domesticus stDNA. In contrast, EcoRI digestion reveals thatM. musculus stDNA lacks most of the GAATTC restriction sites, particularly at the level of the half-monomer. The chromosome distribution of stDNA (revealed by anM. domesticus stDNA probe) shows different patterns in theM. domesticus andM. musculus karyotypes, with about 60% ofM. domesticus stDNA retained in theM. musculus genome. It is particularly noteworthy that the pericentromeric regions ofM. musculus chromosomes 1 and X are totally devoid ofM. domesticus stDNA sequences. In both groups, the differences in energy transfer between the stDNA-bound fluorochromes Hoechst 33258 and propidium iodide suggest that AT-rich repeated sequences have a much more clustered array in theM. domesticus stDNA, as if they are organized in tandem repeats longer than those ofM. musculus. Considering the data as a whole, it seems likely that the evolutionary paths of the two stDNAs diverged after the generation of the ancestral 230–240 bp stDNA repetitive unit through the amplification, in theM. domesticus genome, of a family repeat which included the EcoRI GAATTC restriction sequence.     

Atrial fibrillation and pacing algorithms

Pacing prevention algorithms have been introduced in order to maximize the benefits of atrial pacing in atrial fibrillation prevention. It has been demonstrated that algorithms actually keep overdrive atrial pacing, reduce atrial premature contractions, and prevent short-long atrial cycle phenomenon, with good patient tolerance. However, clinical studies showed inconsistent benefits on clinical endpoints such as atrial fibrillation burden. Factors which may be responsible for neutral results include an already high atrial pacing percentage in conventional DDDR, non-optimal atrial pacing site and deleterious effects of high percentages of apical ventricular pacing. Atrial antitachycardia pacing (ATP) therapies are effective in treating spontaneous atrial tachyarrhythmias, mainly when delivered early after arrhythmia onset and/or on slower tachycardias. Effective ATP therapies may reduce atrial fibrillation burden, but conflicting evidence does exist as regards this issue, probably because current clinical studies may be underpowered to detect such an efficacy. Wide application of atrial ATP may reduce the need for hospitalizations and electrical cardioversions and favorably impact on quality of life. Consistent monitoring of atrial and ventricular rhythm as well as that of ATP effectiveness may be extremely useful for optimizing device programming and pharmacological therapy.     

Root bacterial endophytes confer drought resistance and enhance expression and activity of a vacuolar H+-pumping pyrophosphatase in pepper plants

It has been previously shown that the transgenic overexpression of the plant root vacuolar proton pumps H⁺-ATPase (V-ATPase) and H⁺-PPase (V-PPase) confer tolerance to drought. Since plant-root endophytic bacteria can also promote drought tolerance, we hypothesize that such promotion can be associated to the enhancement of the host vacuolar proton pumps expression and activity. To test this hypothesis, we selected two endophytic bacteria endowed with an array of in vitro plant growth promoting traits. Their genome sequences confirmed the presence of traits previously shown to confer drought resistance to plants, such as the synthesis of nitric oxide and of organic volatile organic compounds. We used the two strains on pepper (Capsicuum annuum L.) because of its high sensitivity to drought. Under drought conditions, both strains stimulated a larger root system and enhanced the leaves' photosynthetic activity. By testing the expression and activity of the vacuolar proton pumps, H⁺-ATPase (V-ATPase) and H⁺-PPase (V-PPase), we found that bacterial colonization enhanced V-PPase only. We conclude that the enhanced expression and activity of V-PPase can be favoured by the colonization of drought-tolerance-inducing bacterial endophytes.     

Changes of plasma insulin, urea, amino acids and rumen metabolites in somatotropin treated dairy cows

Summary An experiment was performed to evaluate the effects of somatotropin on plasma free amino acid, urea and insulin concentrations and rumen fermentation pattern and to assess their relationships. Four Italian Friesian dairy cows fitted with rumen cannulae were used in a switch-back design. Slow releasing recombinant bovine somatotropin (640 mg/cow) was injected every 28 days for two consecutive periods. Rumen fluid and blood samples were collected before and after feeding at 0, 7 and 21 days after rbST injection. Exogenous rbST increased plasma insulin concentration and the insulin response to feeding, and decreased plasma urea and free essential and branched chain amino acid concentrations. rbST did not affect rumen fermentation pattern. No correlation was found between rumen and plasma parameters measured after feeding. Our results are consistent with the notion that the main effect of somatotropin is post-absorptive.     

Immunohistochemical localization of human immunoglobulins and lysozyme in epoxy-embedded lymph nodes: effect of different fixatives and of proteolytic digestion

The postembedding immunoperoxidase staining technique for the localization of immunoglobulins (light and heavy chains) and of lysozyme has been successfully applied to epoxy-embedded human lymph nodes, after removal of the resin. Glutaraldehyde-containing fixatives appear to be suitable for the immunohistochemical localization of human immunoglobulins and lysozyme, provided that the masked antigenicity of these proteins is recovered by proteolytic digestion of the tissue sections using 0.4% pepsin or 0.1% trypsin. Nonglutaraldehyde-containing fixatives allow the immunolocalization of human immunoglobulins without any enzymatic pretreatment. This study shows that tissues routinely fixed in glutaraldehyde and embedded for ultrastructural investigations are actually suitable for immunohistochemical studies on human immunoglobulins and lysozyme.     

Structural patterns of swine ileal mucosa following L-glutamine and nucleotide administration during the weaning period. An histochemical and histometrical study

Dietary supplementations with L-glutamine and/or nucleotides were screened for their effects on intestinal mucosa in 16 female weaning piglets. The animals were transported to the university's facilities 24 hours after weaning. They were grouped four to a pen in controlled environmental conditions and fed one of the following four diets for 28 days: control diet (C); C+0.5% L-glutamine (G); C+0.05% "nucleotides" (N); and C+0.5 % L-glutamine+0.05% "nucleotides" (GN). Individual body weights and feed intake per group were recorded at the beginning and the end of the study as well as weekly during it. There were no significant performance differences among the groups. After 28 days the animals were slaughtered and the distal ileum and liver were examined histologically. Anti-proliferating cell nuclear antigen (PCNA) as well as anti-human macrophage immunostaining, and a modified TdT-mediated dUTP nick-end labeling technique (TUNEL) were performed, and intraepithelial lymphocyte percentage was evaluated to assess morpho-functional aspects of the ileum. Histometry was performed by assessing cell indices and counts of immuno-reactive structures. Feeding G and/or N resulted in an increase in villi (V) height, crypt (C) depth, and a decrease in V:C ratio (P<0.01). In addition, feeding G and/or N resulted in an increase in mitotic mucosal cells (M), and a decrease in apoptotic mucosal cells (A), thus decreasing the A:M index (P<0.01). The percentages of mucosal macrophages were greater in G and/or N groups (P<0.001) than in control piglets, and similarly among the groups the percentages of intraepithelial lymphocytes varied (P<0.01). Our data showed that the diet supplementation with G and/or N had positive effects on some morpho-functional characteristics of piglet ileal mucosa. These ameliorative effects may potentially be linked to a good responsiveness of piglets to a stressful period, like a precocious weaning is in this species.