Recurrence rates following external valvular stenting of the saphenofemoral junction: a comparison with simultaneous contralateral stripping of the great saphenous vein.

OBJECTIVES: The incidence of recurrent varicose veins remains high despite the development of new ablative treatments for varicose veins associated with incompetence of the saphenofemoral junction. External valvular stenting (EVS) of the terminal and/or subterminal valves of the great saphenous vein (GSV) provides a reparative, physiological approach that requires long-term evaluation. The aim of this study was to compare recurrences following EVS with perforate invaginate (PIN) stripping of the GSV. METHODS: Included in the study were 193 patients (386 limbs) all of whom underwent simultaneous PIN-stripping of the GSV in one limb and EVS in the contralateral limb. Duplex scanning of the GSV and venous valves established suitability for each procedure. Only valves with visible, mobile cusps on ultrasound imaging are suitable for EVS. Stents were specifically designed Dacron reinforced silicone for left and right saphenofemoral junctions and for the subterminal valve. In a separate group of patients identified from a database where unilateral and bilateral stents had been implanted, 39 limbs with recurrent varices were examined clinically and ultrasonically to determine the aetiology of recurrences. RESULTS: Follow up was available to a maximum of 147 months. The total recurrence rate was 12.4%; stripping (22.2%) and EVS (4.6%) (P<0.01). The residual reflux as measured by postoperative Valsalva on duplex was 9% but rarely was associated with recurrences. The most common cause of recurrence was incompetent perforators and ovarian vein incompetence filling varices of the pudendal veins. CONCLUSION: This non-randomised study included more severely affected limbs in the PIN stripping limbs, favouring a better outcome in the EVS group. In those patients at an early stage of the disease process where venous valve structure is essentially intact, EVS is a physiological alternative to PIN stripping in the treatment of varicose veins.

A spontaneous murine melanoma lung metastasis comprised of host x tumor hybrids.

Cells from a lung metastasis, arising from Cloudman S91 melanoma cells implanted s.c. in the tail of a BALB/c nu/nu mouse, were comprised chiefly of host x tumor hybrids. These lung metastasis cells showed: (a) 30-40% increased DNA content; (b) resistance to 10(-4) M hypoxanthine, 4 x 10(-7) M aminopterin, and 1.6 x 10(-5) M thymidine (HAT) + G418; and (c) the presence in genomic DNA of genes for both wt and albino tyrosinase, reflecting the DBA/2J (Cloudman S91) and BALB/c mouse genotypes, respectively. Individual clones of lung metastasis cells expressed enhanced pigmentation, motility, and responsiveness to MSH/IBMX, a behavior similar to that recently reported for artificially generated melanoma x macrophage fusion hybrids. These similarities suggested that the host fusion partner generating the lung metastasis hybrids might have been a macrophage, although formal proof for this was not possible. The results provide the first direct evidence that host x tumor hybridization could serve as an initiating mechanism for melanoma metastasis.

Polymerization of 5,6-dihydroxyindole-2-carboxylic acid to melanin by the pmel 17/silver locus protein.

Recent advances in melanogenesis have focused on the role of dihydroxyindole-2-carboxylic acid[(HO)2IndCOOH]. For example, it has been shown that formation of (HO)2IndCOOH from dopachrome is catalyzed by dopachrome tautomerase, that the melanogenic protein tyrosinase-related protein (TRP)-1 can oxidize (HO)2IndCOOH to its indole quinone, that (HO)2IndCOOH-melanins can be synthesized chemically, that mammalian melanins are naturally rich in (HO)2IndCOOH subunits, and that (HO)2IndCOOH is incorporated into melanins of melanomas in mice. The question thus emerges as to the mechanism(s) by which (HO)2IndCOOH and other precursors become incorporated into melanins in vivo. Accordingly, an activity was partially purified that catalyzed melanin formation with (HO)2IndCOOH as a substrate. Analyses of the (HO)2IndCOOH polymerization factor from Cloudman melanoma cells revealed the following: it was proteinaceous in that it was heat labile and destroyed by proteinase K; it was a glycoprotein in that it adhered to wheat germ agglutinin and was eluted with N-acetyl glucosamine; it was located predominantly in the melanosomal fraction of cell homogenates; the activity was reduced by exposure to the metal chelators EDTA and EGTA, but not by phenylthiourea, a tyrosinase inhibitor; the (HO)2IndCOOH polymerization reaction was inhibited by superoxide dismutase. In addition, the activity was found with the mouse pmel 17/silver locus protein immunopurified from human melanoma cells, and was significantly reduced in extracts of mouse melanocytes cultured from silver (si/si) mice compared to extracts from Si/Si melanocytes. In summary, an activity has been identified in human and mouse melanoma cells that catalyzes the superoxide-dependent polymerization of (HO)2IndCOOH to melanin in vitro, and appears to be a function of the pmel 17/silver protein of the human pmel 17 gene and the mouse silver locus.

Melanoma x macrophage fusion hybrids acquire increased melanogenesis and metastatic potential: altered N-glycosylation as an underlying mechanism.

We recently reported that a majority of hybrids generated in vitro between weakly metastatic mouse Cloudman S91 melanoma cells and human or mouse macrophages showed enhanced metastatic potential. With few exceptions, hybrids with enhanced metastatic potential also had elevated basal melanin content and increased responsiveness to MSH compared to parental cells. Here we investigated the hybrid melanotic phenotype in more detail, comparing the pigmentary systems of hybrids and parental Cloudman S91 cells by several techniques. Cells were studied by electron microscopy, cell lysates were analyzed for tyrosinase (E.C.1.14.18.1) activity, and melanosomal proteins were analyzed by gel electrophoresis and immunoblotting. Melanosomes in parental Cloudman melanoma cells were few in number and relatively amorphous, whereas those in the hybrids were numerous and heavily pigmented, containing highly organized lattice structures. Both basal and MSH-inducible tyrosinase activities were elevated several fold in hybrids compared to parental cells. Tyrosinase, TRP-2, and LAMP-1 from hybrids migrated more slowly on gels compared to the same proteins from parental melanoma cells, consistent with increased glycosylation. Migration of LAMP-1 from hybrids was similar to that from peritoneal macrophages, which also appeared to be more heavily glycosylated than LAMP-1 from Cloudman cells. By using 3H-glucosamine as a marker of N-glycosylation, its incorporation into tyrosinase and LAMP-1 was found to be elevated in hybrids, suppressed by N-glycosylation inhibitors, and stimulated by MSH to a greater degree in hybrids compared to parental cells. These results indicate N-glycosylation as an important regulatory pathway for MSH-induced melanogenesis and further suggest that altered N-linked glycosylation may be an underlying mechanism for regulation of both melanogenesis and metastasis in macrophage x melanoma hybrids.