Wound healing in aged animals--effects of locally applied transforming growth factor beta 2 in different model systems.

Local application of a growth factor which could stimulate cell turnover, extracellular matrix synthesis and blood vessel formation in the skin should improve and accelerate wound healing processes which are often impaired in old age. We demonstrate the effects of TGF-beta 2 in promoting wound repair in old animals where normal healing responses are shown to be naturally slower. The potential use of TGF-beta s for the treatment of wound injuries, including chronic non-healing ulcers in the elderly, is discussed.

Improving survival in patients with cirrhosis undergoing major abdominal operations.

Fifty-one patients with cirrhosis underwent 65 major abdominal procedures, with an 8% mortality and a 28% complication rate. Preoperative and perioperative management was comparable to that rendered patients with cirrhosis undergoing portosystemic shunting procedures. Emergency operation, persistent coagulation defects (prothrombin time and partial thromboplastin time prolonged greater than 2 s), blood loss greater than 4 U, and exploration of the common bile duct were factors associated with increased mortality. Major surgical procedures can be safely performed in critically ill patients with cirrhosis with intensive preoperative care and with minimizing intraoperative blood loss.

The gap junctional channel.

Two distinct forms of intercellular communication have been found in animal tissues, one using the familiar, trans-membrane, extracellular route and the other using an entirely intracellular route. The intracellular route depends on specialized, permeable (gap) junctions which form at areas of contact between adjacent cells. The junctions contain aqueous channels which directly link the cytoplasms of the coupled cells. Small ions and molecules pass through these channels and move freely between all cells in coupled populations. The structural protein which forms the gap junctional channel has been isolated and characterized. It has an apparent M.Wt. of 16,000 and readily forms multimeric structures. In the membrane, six protein subunits surround the central aqueous pore. Addition of retinoic acid to cells appears to close the junctional channels. This effect of retinoic acid on the junctional pathway of intercellular communication may explain some of its biological activities.

von Hippel-Lindau disease (angiomatosis of the retina and cerebellum).

von Hippel-Lindau disease is a multi-system disorder characterized by hemangioblastic lesions of the central nervous system and visceral organs. Angiomatosis retinae is often the first observable manifestation of von Hippel-Lindau disease. Optometry may be the initial point of entry into the health care system for the von Hippel-Lindau patient. As such, the eye care practitioner should be aware of the diffuse nature of the disease and initiate the search for silent, possibly lethal, lesions associated with the disease. Management may involve consultation with a neurosurgeon, internist, and retinal specialist. The presentation and clinical course of a young man with von Hippel-Lindau disease is presented.

A factor from a transformed cell line that affects cell migration.

When a monolayer culture of normal Balb/c3T3 cells is wounded by scraping away part of the cell sheet, the cells do not migrate into the cleared area unless there is serum in the culture medium. By contrast, SV40-transformed Balb/c3T3 cells do migrate into the wound area without serum. A quantitative assay for the migration of Balb/c3T3 cells into wounds is described. This assay is used in the partial purification of a migration factor released into serum-free medium by SV28 cells. SV28 is a line of BHK21/13 hamster cells transformed by SV40 chosen for its malignancy. The most purified fractions have about 1500 times the specific activity of whole calf serum. These fractions have an activity that promotes overgrowth of Balb/c3T3 cells to high density and an activity that prolongs cell survival without serum. The SV28 migration factor is not extractable from the medium of untransformed BHK21/13 cells or from serum. This migration factor might contribute to the malignancy of SV28 cells.

Isolation and characterisation of milk growth factor, a transforming-growth-factor-beta 2-related polypeptide, from bovine milk.

A strategy was developed for the purification of a biologically active polypeptide growth and migration factor from skimmed bovine milk. This 25-kDa dimeric molecule, termed milk growth factor (MGF), was isolated by a method consisting of a combination of strong cation-exchange chromatography, low-pressure hydrophobic-interaction chromatography, hydrophobic-interaction HPLC and size-exclusion HPLC steps, which separated the protein according to its properties of charge, hydrophobicity and size, respectively. On average, a total purification of 10(6)-10(7)-fold and a yield of approximately 115 +/- 78 ng/MGF/milk was obtained using the method described. All purification steps were performed with novel combinations of ethanol and volatile acidic salt (ammonium acetate) solutions in order to retain biological activity of the protein. These conditions, together with the easy removal of salt by lyophilization, facilitated the detection of biological activity in fractions collected at each step of the purification by means of a sensitive in vitro fibroblast-migration assay in which the half-maximal activity was obtained at a concentration of approximately 17 +/- 4 pg/ml (i.e. approximately 1 pM) of the pure protein. Biological activity of the dimeric protein was unaffected by heat treatment or exposure to acid (pH 2.0), but was lost upon reduction to its monomeric form. Amino acid composition and sequence analyses demonstrate that MGF is related to transforming growth factor type beta 2.

Mechanism of inhibition of junctional communication between animal cells by phorbol ester.

The tumour promotor 4 beta-phorbol 12-myristate 13-acetate (TPA) reduces the rate of junction formation between V79 Chinese hamster lung cells in culture but not between BHK21/13 Syrian hamster fibroblasts. TPA may act on all cells but only affect junction formation in those situations where the rate of junction formation is already low.

Deficiency in the ability of serum from pigs on an atherogenic diet to stimulate the migration of 3T3 cells in culture.

The serum of pigs developing atherosclerosis is deficient in the ability to stimulate the migration of Balb/c-3T3-A31 cells in culture. This deficiency appears to be due to the presence of an inhibitor located in lipoprotein-free serum. The migration assay was used to follow the changing migration activity of the serum of pigs on a changing diet.

In vivo and in vitro studies on endothelial regeneration.

Endothelial regeneration was studied in rabbit aorta after intra-arterial balloon catheterization. Most of the regenerated endothelium originated from existing branches which was assessed by the Evans-blue uptake pattern and confirmed by transmission and scanning electron microscopy. Glucocorticoid treatment enhanced re-endothelialization whereas hyperlipemic diet inhibited. Sera from minipigs fed an atherogenic diet consistently have less ability than sera from control pigs to stimulate in vitro the regeneration of wounded endothelium-like monolayers of 3T3-B cells. The deficiency is probably due to an inhibitor which appears and disappears with changes in the diet.

Expression of the c-sis gene and secretion of a platelet-derived growth factor-like protein by simian virus 40-transformed BHK cells.

SV40-transformed BHK cells were shown to express two transcripts, of 3.5 kb and 2.0 kb, that hybridised to a human c-sis probe. Antibodies directed against human PDGF specifically recognized a 31 kDa protein in SV40/BHK cell conditioned medium, which upon reduction was split into 16 kDa species. Unfractionated conditioned medium and one of two growth factors isolated from SV40/BHK cells competed with 125I-PDGF for binding to its receptor. The present communication thus provides compelling evidence that an SV40/BHK cell-derived growth factor is a hamster equivalent to human PDGF.

Retinoic acid inhibits junctional communication between animal cells.

Retinoic acid inhibits junctional communication between a variety of vertebrate cell types in culture. It reduces the intercellular transfer of 3H-nucleotides between Syrian hamster kidney fibroblasts (BHK 21/13), Chinese hamster lung fibroblasts (V79), rat liver epithelial cells (BRL), Swiss mouse embryo fibroblasts (3T3), rainbow trout gonadal fibroblasts (RTG2) and Xenopus embryo fibroblasts (Xen). It also reduces metabolic cooperation between hypoxanthine-guanine phosphoribosyl transferase deficient mutant and wild-type BHK cells. The inhibition is rapid (intercellular transfer of iontophoretically injected Lucifer Yellow CH between BRL cells is completely blocked after the cells have been exposed to 10(-4) M retinoic acid for 5 min), and is fully reversed when the drug is removed. Based on these results and the observation that the amount of gap junctional protein isolated from cells grown in the presence of retinoic acid for 1 h is the same and after 24 h is increased (1.3- to 3.1-fold) compared with the amount isolated from untreated cells, we suggest that the inhibitory effect is mediated by the reversible closure of junctional channels.