Connective tissue changes in a mouse model of vein graft disease

AIM

The extracellular matrix plays an important physiological role in the architecture of the vascular wall. In arterialized vein grafts severe early changes, such as thrombosis and neointimal hyperplasia occur. Paclitaxel is in clinical use as antiproliferative coating of coronary stents. We aimed to investigate the early connective tissue changes in arterialized vein grafts and the influence of perivascular paclitaxel treatment in an in vivo model.

METHODS

C57 black mice underwent interposition of the vena cava into the carotid artery. Neointimal hyperplasia, thrombosis, acid mucopolysaccharides (Alcian), collagen fibers (trichrome Masson), elastic fibers, and apoptosis rate (TUNEL) were quantified in paclitaxel treated veins and controls.

RESULTS

In both, controls and paclitaxel treated vein grafts acid mucopolysaccharides and elastic fibers were found predominantly in the neointima, whereas collagen fibers were found mainly in the media and adventitia. At 4 weeks postoperatively the neointimal thickness in controls was 52 (13-130) microm, whereas in 0.6 mg/mL l paclitaxel treated veins it was 103 (43-318) microm (P=0.094). At 8 weeks postoperatively paclitaxel treated veins showed a significantly increased neointimal thickness of 136 (87-199) microm compared with 79 (62-146) microm in controls (P=0.032). There was no difference in apoptosis rate between the two groups (P=NS). Even with the lowest concentration of 0.008 mg/mL paclitaxel veins showed a neointimal thickness of 67 (46-205) microm at 4 weeks postoperatively (P=NS vs controls).

CONCLUSION

Early vein graft disease is characterised by an accumulation of acid mucopolysaccharides and elastic fibers in the thickened neointima. Paclitaxel treatment increases the neointimal hyperplasia in mouse vein grafts in vivo.

Intercomparison of measurement techniques for black or elemental carbon under urban background conditions in wintertime: influence of biomass combustion

A generally accepted method to measure black carbon (BC) or elemental carbon (EC) still does not exist. An earlier study in the Vienna area comparing practically all measurement methods in use in Europe gave comparable BC and EC concentrations under summer conditions (Hitzenberger et al., 2006a). Under summer conditions, Diesel traffic is the major source for EC or BC in Vienna. Under winter conditions, space heating (also with biomass as fuel) is another important source (Caseiro et al., 2007). The present study compares the response of thermal methods (a modified Cachier method, Cachier et al., 1989; a thermal-optical method, Schmid et al., 2001; and two thermal-optical (TOT) methods using Sunset instruments, Birch and Cary, 1996 and Schauer et al., 2003) and optical methods (a light transmission method, Hansen et al., 1984; the integrating sphere method, Hitzenberger et al., 1996; and the multiangle absorption photometer MAAP, Petzold and Schönlinner, 2004). Significant differences were found between the TOT methods on the one hand and all other methods on the other. The TOT methods yielded EC concentrations that were lower by 44 and 17% than the average of all measured concentrations (including the TOT data). The largest discrepancy was found when the contribution of brown carbon (measured with the integrating sphere method) was largest.

Study on the weed-crop competition for nutrients in maize

Considering the effect of crop-weed competition the rate of weed growing, the competitiveness of the occurring weed species and the duration of competition are determining factors. Experiments were carried out on fields in order to collect data on the effect of early weed competition on maize, including the competition for nutrients and the possible rate of nutrient removal by weeds. From 7 sampling areas of the 9.2 ha field weeds and maize samples were collected 1 month after the sowing of maize. We determined the total numbers and the species numbers of weeds by plots. The removed plant species and maize were weighed then dried until the weight balance was reached. The samples were tested for N, P, K and Ca. Comparison was done with the weight and nutrient element content of maize plants taken from the treated, weed-free area. At the same time comparative analyses were made with the mass and nutrient contents of maize plants. There were 12 occurring weed species in this experiment. Based on the rate of weed cover the following species were dominant: Datum stramonium L., Cannabis sativa L., Amaranthus chlorostachis Willd., Chenopodium album L., Chenopodium hybridum L. Our experiments revealed that in the areas being likely to produce high weed populations and showing a considerable high nutrient removal by weeds, the competition between weed plants and maize occurs at an earlier stage of the vegetation period of maize than on fields with moderate weed populations. Weeds have utilised significant amount of nutrients which has been many fold of maize in case of unit area.

Kunitz-type proteinase inhibitors derived by limited proteolysis of the inter-alpha-trypsin inhibitor, X. The amino-acid sequences of the trypsin-released inhibitors from horse and pig inter-alpha-trypsin inhibitors

The amino-acid sequences of the acid-resistant inhibitors released from horse and pig inter-alpha-trypsin inhibitor (ITI) by tryptic proteolysis were determined. They are composed of two covalently linked Kunitz-type domains. In both cases the reactive site of their C-terminal antitryptic domains is occupied by arginine as in the homologous human and bovine inhibitors. The reactive site of their N-terminal domain exhibits only a weak interaction with polymorphonuclear granulocytic elastase and is occupied by leucine as in the strong elastase inhibitor released from bovine ITI. The differences between inhibitory activities of the ITI-derived inhibitors from horse, pig, and cattle are discussed on the basis of sequence differences in position P'2.

Human inter-alpha-trypsin inhibitor: localization of the Kunitz-type domains in the N-terminal part of the molecule and their release by a trypsin-like proteinase

The N-terminal amino-acid sequence of human ITI has been found to be identical with that of the acid-stable human 30-kDa inhibitors (HI-30) from urine, serum, and those released from inter-alpha-trypsin inhibitor by trypsin or chymotrypsin. Serum HI-30 and HI-30 released by trypsin differ from the urinary inhibitor by an additional C-terminal arginine residue. Compared to these two inhibitors the inhibitor released by chymotryptic proteolysis is elongated C-terminally by an additional phenylalanine residue. These results strongly favour HI-30 as the N-terminus of the inter-alpha-trypsin inhibitor and its release from this inhibitor in vivo by cleavage of the Arg123-Phe124 peptide bond by trypsin-like proteinases.

Isolation of acid-resistant urinary trypsin inhibitors by high performance liquid chromatography and their characterization by N-terminal amino-acid sequence determination

Two crude fractions of acid-resistant trypsin inhibitors (apparent molecular masses 44 and 20 kDa, respectively) were prepared from human urine by gel permeation chromatography. From both preparations the pure inhibitors were isolated by high performance liquid chromatography (HPLC). Their N-terminal amino-acid sequences were determined and compared with those of HI-30 and HI-14 as isolated by reversible binding to either immobilized trypsin or immobilized chymotrypsin. The N-terminal amino-acid sequence of the high-molecular mass inhibitor UI-I isolated by HPLC was identical with those of HI-30 and UI-C-I isolated via immobilized trypsin or chymotrypsin, respectively. The low-molecular mass inhibitors UI-II and UI-C-II differ from HI-14 by the N-terminal extension Glu-Val-Thr-Lys-when obtained by HPLC or by the extension Thr-Lys-when obtained via immobilized chymotrypsin, respectively. The comparison of these N-termini with the amino-acid sequence of HI-30 (Ala1-...-Val16-Thr-Glu-Val-Thr-Lys-HI-14) defines the low molecular urinary trypsin inhibitors as proteolytic degradation products of the high-molecular urinary inhibitor. Proteolysis may occur at different bonds. The existing discrepancies in molecular architecture and in molecular masses of the urinary trypsin inhibitors are discussed.

Hemocyanins in spiders, XIX. Complete amino-acid sequence of subunit d from Eurypelma californicum hemocyanin, and comparison to chain e

The complete primary structure of subunit d of the hemocyanin from the tarantula Eurypelma californicum was determined by manual micro sequencing. Subunit d of Mr = 73000 is split about in the middle of the chain during limited trypsinolysis, only one single bond being attacked. The whole chain contains 14 methionine residues and after cyanogen bromide cleavage 15 peptides could be isolated by gel and ion exchange chromatography and high pressure liquid chromatography. The cyanogen bromide peptides and the large (Mr = 34000 and 37000, respectively) fragments resulting from limited trypsinolysis, were further cleaved with trypsin, chymotrypsin, Staphylococcus aureus proteinase, formic acid, and Astacus fluviatilis proteinase, the latter being very useful in obtaining certain overlapping peptides. The total chain length is 627 residues. Carbohydrate side chains were not found. The sequence is discussed with respect to the gross physical properties of the subunit, to homologies with subunit e and the cleavage specifities of the enzymes employed.

The effect of nisin on murein synthesis

Nisin inhibits murein synthesis with concomitant accumulation of undecaprenyl-pyrophospho-MurHAc(pentapeptide) (lipid intermediate I). This inhibition is caused by the formation of a complex between the antibiotic and lipid intermediate I. Undecaprenyl-pyrophospho-MurNAc(pentapeptide)-GlcNAc (lipid intermediate II) also forms a complex with nisin. However, when murein synthesis is inhibited by nisin, this latter complex is not formed since lipid intermediate II is not longer synthesized.