Left ventricular assist device exchange for persistent infection: a case series and review of the literature.

Left ventricular assist device (LVAD) exchange for control of infection may be an option for the treatment of persistent and severe infections of the LVAD. Data are limited regarding the indications for device exchange, methods for exchanging infected devices, post-exchange antimicrobial management, and outcomes of such patients. We report a series of cases in which an exchange was performed for persistent LVAD infection, review the literature on LVAD exchange and surgical techniques for these infectious complications, and suggest management strategies from a multidisciplinary perspective.

Biphasic effect of vanadium salts on in vitro tumor colony growth.

Vanadium is a trace element widely distributed in nature. It interferes with a variety of enzyme systems and is also reported to increase DNA-synthesis and in vitro clonal growth of human and mouse fibroblasts. The purpose of the present study was to determine the effect of vanadium salts on the in vitro growth of fresh human tumor specimens. Various concentrations of ammonium metavanadate (AMV), vanadyl sulfate trihydrate (VST) and ortho sodium vanadate (OSV) were tested in a human tumor cloning assay (HTCA). Thirty-four evaluable specimens were tested at concentrations of less than or equal to 10(-10) M of one or more vanadium salts. At this concentration, colony formation was increased by greater than or equal to 150% as compared to control at one or more concentrations in 16 specimens (47%). Twelve evaluable specimens were tested against various concentrations greater than 10(-10) M. Colony formation was inhibited by greater than or equal to 50% of the control at one or more concentrations in all specimens. In further experiments we performed a head-to-head comparison of OSV (10(-3)M) and our standard positive control for cell kill (chromomycin A3, 100 micrograms/ml) in 34 specimens. OSV led to a comparable or better cell kill in 28 tumors (82%). We conclude that vanadium salts at low concentrations (less than or equal to 10(-10)M) can stimulate in vitro colony formation from human tumors. At higher concentrations (greater than 10(-10)M) tumor colony formation is inhibited. OSV might be useful as a very inexpensive positive control in the HTCA. In addition, the value of vanadium salts as antitumor agents should be further investigated in vivo.

Assessment of biological activity of linear alpha-transforming growth factor and monospecific antibodies to alpha-transforming growth factor and linear alpha-transforming growth factor.

alpha-Transforming growth factors (TGFs) are low-molecular-weight polypeptides (Mr 5000-7000) which are secreted by a variety of human cancer cells in vitro. Their presence has also been reported in the urine of patients with malignancies, human tumor extracts, and in the conditioned medium of primary human tumor cell cultures. There is evidence that alpha-TGFs bind to membrane receptors of the secreting cells, thus stimulating cell growth in a positive feedback manner (autocrine secretion). We have used a synthetic linear alpha-TGF to study the biological activity of affinity-purified polyclonal sheep antibodies against the carboxyterminal part (17 amino acids) of synthetic rat alpha-TGF. The antigen was found to bind to epidermal growth factor receptors of target cells and to stimulate soft agarose colony formation of normal fibroblasts. Although the antibodies recognized the linear alpha-TGF molecule, they did not inhibit the binding to epidermal growth factor receptors. The antibodies also failed to inhibit alpha-TGF-stimulated colony formation of normal rat fibroblasts. In addition, essentially no cytotoxic activity of the antibodies was found against 41 fresh human tumor specimens in a human tumor cloning assay. Antibodies against the complete alpha-TGF molecule should be used in further attempts to interfere with the autocrine secretion of transforming growth factors.