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We investigated the involvement of nitric oxide in Schistosoma-induced liver injury. We found that inducible nitric oxide synthase mRNA became detectable in the liver at the onset of parasite egg laying and levels then increased as the eggs accumulated in the organ. Enzyme concentration and activity paralleled mRNA levels. The event was a direct effect of egg deposition, as it occurred in the liver after natural infection, or in the lungs after i.v. injection of the eggs. However, nitric oxide seems to have no direct effect on the eggs since in vitro assays showed that the nitric oxide donor SIN-1 did not alter the ability of the eggs to hatch. L-Arginine and L-NAME, a nitric oxide synthase inhibitor, were administered to infected mice in an attempt to increase or reduce nitric oxide production, respectively. Arginine had no effect on the disease, whereas the inhibitor led to a marked decrease of hepatic injury with, in particular, reduced fibrosis and decreased lipid peroxidation. In conclusion, not only is inducible nitric oxide synthase activity unlikely to exert an anti-microbicidal effect against the egg stage of S. mansoni but it might lead to deleterious effects in the liver and therefore contribute to the pathology.

Lithostathine (pancreatic stone protein, Reg protein) is, in addition to albumin, the major nonenzymatic protein of the pancreatic juice. It has been assumed to inhibit calcium carbonate precipitation and therefore to prevent stone formation in the pancreatic ducts. This function is, however, debatable. The assumption is based on the inhibition of in vitro crystal nucleation and growth by lithostathine. Considering that these phenomena occur only under certain critical conditions, we re-examined the question using a protein preparation where the purity and folding have been tested by mass spectroscopy and NMR in the absence of nonprotein contaminants. Under these conditions, we showed conclusively that lithostathine does not inhibit calcium carbonate nucleation and crystal growth. We demonstrated that previous findings on the alleged inhibition can be attributed to the uncontrolled presence of salts in the protein preparation used. Moreover, the affinity of lithostathine to calcite crystals, expressed as the half-life of bound iodinated protein in the presence of unlabeled competitor, was significantly lower than that of bovine serum albumin (8.8 and 11.2 h, respectively). Using glass microspheres instead of crystals did not significantly change the half-life of bound lithostathine (8.0 h). These findings are incompatible with the hypothesis of a specific interaction of lithostathine with calcium carbonate crystals. In conclusion, considering that components of pancreatic juice such as NaCl and phosphate ions are powerful inhibitors of calcium carbonate crystal growth, the mechanism of stone formation in pancreatic ducts must be reconsidered. The presence in normal pancreatic juice of small amounts of the 133-residue isoform of lithostathine (PSP-S1), which precipitates at physiological pH, should be noted, and the possibility should be considered that they form micro-precipitates that aggregate and are progressively calcified.

• Intraoperative arteriography was carried out using a specially constructed operating table and long x-ray film changer that permitted rapid serial exposure of the arterial reconstruction and the distal arteries. During a ten-year period, this method was applied in 1,810 arterial reconstructions, with technical problems being detected in 82 (4.6%) of these patients. The incidence of problems was highest in patients undergoing endarterectomy, where 16.7% of the patients were found to have either residual debris in the cleared segment or areas of stenosis. When bypass grafts were used, technical problems were found in 2.2% of patients and included embolism or thrombosis, graft torsion in vein grafts, stenosis of the distal anastomosis, and the creation of an intimal flap. In the entire series, five patients needed reoperation in the early postoperative period. In three of these, the operative arteriograms had been initially misread.(Arch Surg 112:1115-1118, 1977)

Adult individuals of the SymphylaHanseniella ivorensishad their antennae cut off at the beginning of the first adult stage; this had the effect of triggering the following molt, which occurred 7.5 days after the treatment. We determined, by a radioimmunoassay method, that ecdysteroids were present in the Symphyla throughout the period studied. They were composed mainly of β-ecdysone but small amounts of α-ecdysone and of high polar products were also detected. During the artificially-induced molting process, the ecdysteroid level showed a smooth peak which took place 5 days after the amputation of the antennae. This indicates that ecdysones probably control the molt in the Symphyla as they do in insects or in crustacea. However, the increase in the hormonal level appears to be not the primary response to the treatment.

Ecdysone haemolymph levels have been analyzed in neck- or thorax-ligatedPierislarvae in order to explain the physiological significance of critical periods. It appeared that head critical period corresponds to an incomplete activation of prothoracic glands, while the thoracic critical period is related to the secretion of a minimal amount of ecdysone necessary for moulting. DuringPieris'last larval instar, there is no evidence for any noticeable synthesis of ecdysone in isolated abdomens.

RIA of ecdysones are made on nymphal extracts ofPisaura mirabilisduring the intermoulting cycle. The hormone level is low during exuviation and the greatest part of the intermoulting period but increases notably before and after ecdysis. The main hormonal peak or pre-ecdysial peak is due to β-ecdysone, characterized by combined TLC/RIA.

Embryos of the diapausing strain ofLepidosaphes ulmishowed a low ecdysteroid level at the onset of diapause whereas an ecdysteroid peak occurred at the same stage in the non-diapausing strain. This observation, together with the effects of 20-OH-ecdysone on diapausing eggs, strongly suggests that this hormone inhibits diapause in embryos.

Bursicon active hemolymph ofTenebrio, injected into host pupae deprived in bursicon, induces a 2-fold increase of cyclic AMP in the epidermis of the hosts 5 min after the injection. No increase is observed by injecting bursicon inactive hemolymph or insect Ringer. From these experiments it can be concluded that cyclic AMP is a second messenger of bursicon.