Acquired and inherited thrombophilic factors and the risk for residual venous thrombosis

Acquired and inherited thrombophilic factors increase the risk for (recurrent) venous thrombotic disease. However, little is known about the pathophysiological mechanisms causing these recurrences, or the persistence of thrombosis despite adequate treatment. Because residual thrombosis has been associated with a worse prognostic outcome, we performed an explorative study in order to investigate the prevalence of residual thrombotic lesions after anticoagulant treatment in patients with deep venous thrombosis. Thrombotic parameters as assessed by ultrasonography after a 12-week course of anticoagulants were used. Both thrombophilia in general and acquired thrombophilia in particular were found to be associated with the extent of residual thrombosis. Of the individual thrombophilic factors, protein C deficiency, prothrombin 20210A mutation, active malignant disease and lupus anticoagulant were associated with an increased risk of residual thrombotic mass. Patients with inherited thrombophilia did not differ from patients without any thrombophilic abnormality with regard to residual thrombotic mass [relative risk (RR) 1.3, 95% confidence interval (CI) 0.9-1.8], while acquired thrombophilic disorders increased the risk for residual thrombotic mass as compared to patients without any defect (RR 1.7, 95% CI 1.2-2.2). Although these results should be confirmed in a larger study, they might help us form hypotheses concerning why patients with thrombophilia are more prone to recurrent venous thromboembolic disease.     

The effects of leukotrienes,thromboxane A2 and phospholipase A2 on human,porcine and guinea pig lung parenchyma

A comparison was made of the contractions, induced by LTD₄, histamine and phospholipase A₂ in parenchymal strips of guinea pig (GPLP), porcine and human lung in a cascade superfusion system. The effects of LTD₄ and phospholipase A₂ on the release of TxA₂ in these tissues and of TxA₂, 5-HT and acetylcholine on the GPLP were also determined.In the GPLP strip, the LTC₄-induced contractions are due for±80% to the release of TxA₂ and for±20% to the direct effect of LTC₄.The guinea pig tissue displayed the highest sentivity towards all substances, except to the contraction induced by histamine, which was most effective in the porcine tissue. Low activities wer found in the human tissue in all tests. The reason for these effects may be a difference in activities or number of cell types which participate in the reactions leading to the contractions.     

Ultraviolet light-induced modification of crosslinked hyaluronan gels

Hyaluronan (HA) gels (hylans) crosslinked with divinyl sulfone (DVS) are highly biocompatible and can be structurally modified to obtain desired mechanical properties that are attractive for their use as tissue-engineering scaffolds. However, unmodified hylan gels are not good substrates for cell attachment or infiltration, likely as a result of their smooth surface and the highly anionic nature of HA. This study investigated whether the cell-adhering characteristics of hylan gels could be enhanced by irradiation with ultraviolet (UV) light, with or without prior dehydration. The attachment and proliferation of neonatal rat smooth muscle cells atop these gels was compared with that on unmodified (control; C) or dehydrated (D) gels. UV-induced changes to gel structure and chemistry were characterized by confocal and electron microscopy, and fluorphore-assisted carbohydrate electrophoresis (FACE). Cell attachment was sparse on both unmodified (C) and dehydrated (D) gels. Significantly higher levels of cell attachment were observed on the surface of irradiated (UV) and dehydrated-irradiated (DUV) gels, likely because of texturing of the gel surface by UV light. In addition, dehydration of gels before UV irradiation created irregular pore-like structures through which cells appeared to migrate into the interior. FACE assays demonstrated that UV-irradiation alters the chemistry of HA, causing limited breakdown of HA chains and DVS crosslinks within gel and possibly creating new crosslinks that have not yet been identified. Because the hylan gels are altered structurally and chemically, binding of cells to the material is likely to be more permanent than possible by other approaches, such as coating of cell-adhesive matrix factors on the gel surface, described previously. The significance of this work is that we have developed a technique for the modification of DVS-crosslinked HA (hylans) to enhance their performance as a cellular scaffold for tissue-engineering applications.     

Mapping of MRX81 in Xp11.2-Xq12 suggests the presence of a new gene involved in nonspecific X-linked mental retardation

X-linked nonspecific mental retardation (MRX) accounts for approximately 25% of mental retardation in males. A number of MRX loci have been mapped on the X chromosome, reflecting the complexity of gene action in central nervous system (CNS) specification and function. Eleven MRX genes have been identified, but many other causative loci remain to be refined to the single gene level. In 21 MRX families, the causative gene is located in the pericentromeric region; and we report here the identification by linkage analysis of a further such locus, MRX81. The new MRX locus was identified by two- and multi-point parametric analysis carried out on a large Italian family. Tight linkage of MRX81 to DNA markers ALAS2, DXS991, and DXS7132 was observed with a maximum LOD score of 3.43. Haplotype construction delineates an MRX81 critical region of 8 cM, the smallest MRX pericentromeric interval so far described, between DXS1039 and DXS1216, and placing it in Xp11.2-Xq12. So far, automated sequencing of two candidates in the region, the MRX gene oligophrenin (OPHN1) and the brain-specific ephrinB1 (EFNB1) gene, in DNA from affected males excluded their candidacy for MRX81, suggesting a novel disease gene.     

Three-dimensional tissue engineering of hyaline cartilage: comparison of adult nasal and articular chondrocytes

Adult chondrocytes are less chondrogenic than immature cells, yet it is likely that autologous cells from adult patients will be used clinically for cartilage engineering. The aim of this study was to compare the postexpansion chondrogenic potential of adult nasal and articular chondrocytes. Bovine or human chondrocytes were expanded in monolayer culture, seeded onto polyglycolic acid (PGA) scaffolds, and cultured for 40 days. Engineered cartilage constructs were processed for histological and quantitative analysis of the extracellular matrix and mRNA. Some engineered constructs were implanted in athymic mice for up to six additional weeks before analysis. Using adult bovine tissues as a cell source, nasal chondrocytes generated a matrix with significantly higher fractions of collagen type II and glycosaminoglycans as compared with articular chondrocytes. Human adult nasal chondrocytes proliferated approximately four times faster than human articular chondrocytes in monolayer culture, and had a markedly higher chondrogenic capacity, as assessed by the mRNA and protein analysis of in vitro-engineered constructs. Cartilage engineered from human nasal cells survived and grew during 6 weeks of implantation in vivo whereas articular cartilage constructs failed to survive. In conclusion, for adult patients nasal septum chondrocytes are a better cell source than articular chondrocytes for the in vitro engineering of autologous cartilage grafts. It remains to be established whether cartilage engineered from nasal cells can function effectively when implanted at an articular site.     

Synthesis of amphiphilic star-shaped and graft copolymers based on polystyrene and poly(ethylene oxide)

Amphiphilic block macromonomers possessing a central unsaturation were synthesized by condensation of polystyrene half-ester of maleic acid {α-[2-(3-carboxyacryloyloxy)ethyl]-ω-sec-butylpoly[1-phenylethylene]} with poly(ethylene glycol) monoether or polystyrene-block-poly(ethylene oxide). In the radical monomer cis-trans-isomerization homopolymerization of the diblock macromonomers, four-to eight-armed amphiphilic star-shaped copolymers were obtained. Radical copolymerization of the diblock macromonomers with styrene led to graft copolymers with low degree of grafting. The triblock macromonomers proved to be unable to polymerize.     

Localizing a putative mutation as the major contributor to the development of sporadic Hirschsprung disease to the RET genomic sequence between the promoter region and exon 2

Hirschsprung disease (HSCR), a congenital disorder characterized by intestinal obstruction due to absence of enteric ganglia along variable lengths of the intestinal tract, occurs both in familial and sporadic cases. RET mutations have been found in approximately 50% of the families, but explains only a minority of sporadic cases. This study aims at investigating a possible role of RET in sporadic HSCR patients. Haplotypes of 13 DNA markers, within and flanking RET, have been determined for 117 sporadic HSCR patients and their parents. Strong association was observed for six markers in the 5' region of RET. The largest distortions in allele transmission were found at the same markers. One single haplotype composed of these six markers was present in 55.6% of patients versus 16.2% of controls. Odds ratios (ORs) revealed a highly increased risk of homozygotes for this haplotype to develop HSCR (OR>20). These results allowed us to conclude that RET plays a crucial role in HSCR even when no RET mutations are found. An unknown functional disease variant(s) with a dosage-dependent effect in HSCR is likely located between the promoter region and exon 2 of RET.     

Identification and distribution ofEchinostoma lindoense,E. audyi andE. revolutum (Trematoda; Echinostomatidae)

The closely relatedEchinostoma lindoense, E. audyi andE. revolutum can be differentiated by morphological characteristics of their adults and cercariae. We have foundE. lindoense andE. audyi in Southeast and Southwest Asia and Central Europe and the former species also in South America. However, using the morphological characteristics described by Beaver (1937) forE. revolutum which is assumed to be cosmopolitan, we did not find this species in these regions.     

Heart development in the spotted dolphin (Stenella attenuata)

Marine mammals show many deviations from typical mammalian characteristics due to their high degree of specialization to the aquatic environment. In Cetaceans, some of the features of limbs and dentition resemble very ancestral patterns. In some species, hearts with a clearly bifid apex (a feature normally present during mammalian embryogenesis prior to completion of ventricular septation) have been described. However, there is a scant amount of data regarding heart development in Cetaceans, and it is not clear whether the bifid apex is the rule or the exception. We examined samples from a unique collection of embryonic dolphin specimens macroscopically and histologically to learn more about normal cardiac development in the spotted dolphin. It was found that during the dolphin's 280 days of gestation, the heart completes septation at about 35 days. However, substantial trabecular compaction, which normally occurs in chicks, mice, and humans at around that time period, was delayed until day 60, when coronary circulation became established. At that time, the apex still appeared bifid, similarly to early fetal mouse or rat hearts. By day 80, however, the heart gained a compacted, characteristic shape, with a single apex. It thus appears that the bifid apex in the adult Cetacean heart is probably particular to certain species, and its significance remains unclear.