Schistosoma mansoni: schistosomulicidal activity of macrophages isolated from liver granulomas of infected mice

Mice infected with Schistosoma mansoni develop T cell-mediated granulomatous reactions around disseminated parasite eggs. In this study, granuloma-derived leucocytes have been examined for schistosomulicidal capacity by the use of in vitro cytotoxicity assays. Adherent macrophages, that were shown by electron microscopy to exhibit no gross morphological abnormalities, were unable to mediate significant mortality in the absence of serum factors. When cocultured with immune serum and complement, however, these cells killed +/- 26% of the larvae at a cell:target ratio of 5000:1. In contrast, granuloma-derived cell populations that were enriched for eosinophils (50-70% eosinophil content) showed only minimal cytotoxic potential. This may be related to observed structural changes in the eosinophil lysosomal granules, or perhaps to blocking of the cell-surface receptors by immune complexes. It is concluded that granuloma macrophages, activated by egg antigen-sensitised T lymphocytes, may serve as effector cells in immunity to schistosomules.     

Organ-dependent differences in composition and function observed in hepatic and intestinal granulomas isolated from mice with Schistosomiasis mansoni

In murine schistosomiasis mansoni, eggs deposited in the liver and intestines induce a cell-mediated granulomatous reaction. Previous studies have shown that maximal granuloma size differs in the liver and various segments of the gastrointestinal tract. The objective of this investigation was to isolate intestinal granulomas and to determine whether organ-dependent differences in cell composition and granuloma function exist. Intestinal granulomas representative of those in tissue were isolated by a combination of chemical and mechanical techniques. When dissociated by collagenase, these lesions yielded a viable heterogeneous population of inflammatory cells. Granulomas from the liver, colon, and ileum showed differences in cellular composition. Liver lesions contained the largest number of T and B lymphocytes, eosinophils, and mast cells whereas ileal granulomas comprised mostly macrophages. Immunofluorescence studies on frozen tissue sections revealed that T and B lymphocytes also displayed different patterns of distribution within granulomas from different tissues. In contrast to isolated cultured liver granulomas that produced MIF-like substances, isolated colonic and ileal granulomas had weak or no MIF activity. It thus appears that granuloma formation in various organs is influenced by local factors that could affect the ultimate resolution of the lesions.     

Synthesis of 6-deoxy-5-thio-d-glucose

Three routes were investigated for the conversion of d-glucose into the title compound. In the first approach, reduction of the 5,6-thürane ring of 5,6-dideoxy-5,6-epithio-1,2-O-isopropylidene α-d-glucofuranose (17) as well as that of its 3-O-allyl derivative (13) with lithium aluminium hydride was investigated; 17 afforded the corresponding 6-deoxy derivative besides di-, tri-, and poly-mers, whereas only polymers were formed from 13. In the second approach, the oxirane ring of was reduced by sodium borohydride and the resulting 6-deoxy derivative was converted into the 5-thiobenzoate; the corresponding hex-4-enofuranose was formed as a byproduct. In the third approach partial mesylation of methyl 5-thio-α-d-glucopyranoside was attempted, but the 6-mesylate 27 could be isolated only in modest yield (28%) together with rearranged 2,5-thioanhydromannofuranoside derivatives. The mechanism of this rearrangement is discussed in detail. The 6-mesylate 27 was converted via the 6-iodo derivative into the title compound.     

Appearance and some neurochemical features of nitrergic neurons in the developing quail digestive tract

Using immunocytochemistry, NADPH-diaphorase (NADPHd) histochemistry and electron microscopy, the appearance of nitrergic enteric neurons in different digestive tract regions of the embryonic, neonatal and adult quail was studied in whole mounts and sections. NADPHd was first expressed by embryonic day 4–5 in two distinct locations, namely the mesenchyme of the gizzard primordium and at the caeco-colonic junction. At embryonic day 6, nitrergic neurons had already begun to form a myenteric nerve network in the wall of the proventriculus, gizzard and proximal part of the large intestine and by embryonic day 9, a myenteric network was visualized along the entire digestive tract of the quail. At the level of the stomach, this network was confined to the area covered by the intermediate muscles. By embryonic day 12–13, the NADPHd-positive myenteric neurons in the wall of the distal parts of the blind-ending paired caeca also became organized into ganglia. From this developmental stage on, a submucous nitrergic nerve network, sandwiched between the lamina muscularis mucosae and the luminal side of the outer muscle layer, became prominent in the proventriculus and intestinal walls. In the adult quail, only a minority of the NADPHd-positive neurons stained for vasoactive intestinal polypeptide (VIP) along the intestine. VIP-immunoreactive (IR) cell bodies were frequent in the myenteric plexus but not in the submucous plexus, whereas there were considerable numbers of NADPHd-positive neurons in both these plexuses. Nitrergic fibres were also observed in the outer muscle layer, but were almost absent from the lamina muscularis mucosa and lamina propria, in contrast to the dense VIP-ergic innervation encircling the bases of the intestinal crypts.     

Restriction endonuclease analysis of the transducing bacteriophage lambda rif d18

The rif d18 bacteriophage carries essential parts of the E. coli genome which can not be mapped by conventional methods. The phage DNA was analysed with four restriction endonucleases (endo R. BamHI, Sall, HpaI and EcoRI) and a physical map was constructed.     

Physical map of the seven ribosomal RNA genes of Escherichia coli.

Escherichia coli DNA was digested with restriction endonucleases BamHI, PstI, EcoRI, SalI, HindIII, XhoI, BglII, SmaI, HpaI and with selected double and triple combinations of the same enzymes. The digests were electrophoresed and hybridized with 32P-labelled ribosomal RNA by using the Southern blotting technique. The resulting bands could be arranged into seven groups, and it was possible to construct a unique physical map of the seven rRNA genes (operons) of the bacterial chromosome. Mapping information obtained on several transducing phages and recombinant plasmids carrying rRNA genes, and mapping data published in the literature helped to determine the final map. The results suggest that phage lambda daroE152 carries a "hybrid" rRNA gene which was probably formed by recombination between two different chromosomal rRNA genes.     

Scavenging behaviour and size-dependent carcass consumption of the black bullhead (Ameiurus melas)

This study examined the size-dependent scavenging behaviour of black bullheads Ameiurus melas under laboratory conditions, using common bleak Alburnus alburnus and pumpkinseed Lepomis gibbosus carcasses. Video camera observations showed that the activity of A. melas was higher at night, but substantial daytime activity was also recorded. Larger A. melas were more active than their smaller conspecifics, especially at night. All size classes exhibited a well-defined sequence of consuming different parts of the carcasses independent of size, but larger individuals tended to consume carcasses more efficiently. Carcasses of the softer-bodied A. alburnus were consumed more readily than those of the bonier L. gibbosus, independent of size. This scavenging behaviour of A. melas might facilitate the invasion success of the species.     

Inhaled Methane Limits the Mitochondrial Electron Transport Chain Dysfunction during Experimental Liver Ischemia-Reperfusion Injury

Background

Methanogenesis can indicate the fermentation activity of the gastrointestinal anaerobic flora. Methane also has a demonstrated anti-inflammatory potential. We hypothesized that enriched methane inhalation can influence the respiratory activity of the liver mitochondria after an ischemia-reperfusion (IR) challenge.

Methods

The activity of oxidative phosphorylation system complexes was determined after in vitro methane treatment of intact liver mitochondria. Anesthetized Sprague-Dawley rats subjected to standardized 60-min warm hepatic ischemia inhaled normoxic air (n = 6) or normoxic air containing 2.2% methane, from 50 min of ischemia and throughout the 60-min reperfusion period (n = 6). Measurement data were compared with those on sham-operated animals (n = 6 each). Liver biopsy samples were subjected to high-resolution respirometry; whole-blood superoxide and hydrogen peroxide production was measured; hepatocyte apoptosis was detected with TUNEL staining and in vivo fluorescence laser scanning microscopy.

Results

Significantly decreased complex II-linked basal respiration was found in the normoxic IR group at 55 min of ischemia and a lower respiratory capacity (~60%) and after 5 min of reperfusion. Methane inhalation preserved the maximal respiratory capacity at 55 min of ischemia and significantly improved the basal respiration during the first 30 min of reperfusion. The IR-induced cytochrome c activity, reactive oxygen species (ROS) production and hepatocyte apoptosis were also significantly reduced.

Conclusions

The normoxic IR injury was accompanied by significant functional damage of the inner mitochondrial membrane, increased cytochrome c activity, enhanced ROS production and apoptosis. An elevated methane intake confers significant protection against mitochondrial dysfunction and reduces the oxidative damage of the hepatocytes.