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Biomedical subjects

V Falanga

Publications and source records attributed to V Falanga.

At least 19 recordsLinked to original sources
PubMed1992

The effects of endothelin-1 on human dermal fibroblast growth and synthetic activity.

Endothelin-1 (ET-1) is the most potent vasoconstricting substance known, and is believed to have a fundamental role in the regulation of blood flow. It is a peptide produced and secreted by endothelial cells in response to hypoxia and injury, as well as by macrophages. These properties suggest that ET-1 may play a role during tissue repair. In this study, we have examined the effects of ET-1 on the growth and synthetic activity of human dermal fibroblasts. ET-1 stimulated DNA synthesis in serum-deprived cultures: this effect reached a mean value of 64% more than control (P < 0.01) at 2.5 ng/ml (10(-9) M) of ET-1. In contrast, the addition of ET-1 to fibroblasts at different densities and in 0, 3, or 10% fetal bovine serum (FBS) failed to increase cell counts. In 1% FBS, a 41% mean increase in cell counts compared to control values was observed in cultures treated with 2.5 ng/ml of ET-1 (P < 0.01). Incubation of dermal fibroblast cultures at 37 degrees C for 1 hr with increasing concentrations of 125I-ET-1 resulted in saturable binding and a half-maximal specific binding of 27.5 pM. Scatchard plot analysis of the binding showed a Kd of 224 pM and 11,400 high-affinity binding sites per cell. ET-1 had no effect on [14C]-glucosamine incorporation by fibroblasts and caused no increase in collagen synthesis, as measured by collagenase-sensitive [3H]proline incorporation and by salt precipitation of 3H-labeled collagen at acid and neutral pH successively.(ABSTRACT TRUNCATED AT 250 WORDS)

Cell Division↗
PubMed1992

Features of an autoimmune process in mid-dermal elastolysis.

Mid-dermal elastolysis is a rare disorder that is manifested clinically by wrinkling and histologically by the selective absence of elastic fibers in the mid dermis. We describe a young woman who developed abnormal wrinkling after augmentation mammoplasty with silicone implants. Histologic examination confirmed the diagnosis of mid-dermal elastolysis. In addition, a positive antinuclear antibody titer and a false-positive Lyme titer were subsequently detected. In a previously reported case a patient who had mid-dermal elastolysis also had an unusual false-positive pattern for Lyme disease. Silicone mammoplasty has been associated with connective tissue diseases. This report adds mid-dermal elastolysis to the list of diseases associated with augmentation mammoplasty and, along with the presence of autoantibodies, supports autoimmune involvement in mid-dermal elastolysis.

Adult↗
PubMed1992

Skin distribution and differential expression of transforming growth factor beta 1 and beta 2.

Transforming growth factor beta (TGF-beta) 1 and 2 have both become increasingly important in cutaneous biology, but their expression and distribution in human skin are not entirely clear. In this report, normal forearm skin from four volunteers was investigated for TGF-beta 1 and beta 2 immunostaining with antibodies that detect preferentially either cell- or matrix-associated forms of these peptides. Marked cell-associated TGF-beta 1 was found in the dermis, particularly around blood vessels and ducts; cellular TGF-beta 2 immunostaining was less prominent, and was predominantly around blood vessels. Neither TGF-beta 1 nor -beta 2 could be detected in the epidermis or epithelial structures, and the dermal matrix contained minimally detectable amounts of the two isoforms. In all cases, dermal matrix and cells contained greater amounts of TGF-beta 1 than TGF-beta 2. Previous studies have shown that both TGF-beta 1 and -beta 2 can induce dramatic increases in extracellular matrix, and both peptides have been implicated in the pathogenesis of fibrosis. We therefore investigated TGF-beta 1 and -beta 2 immunostaining in involved forearm skin of four patients with systemic sclerosis. Compared to normal skin, fibrotic specimens showed increased amounts of matrix and epidermal TGF-beta 1, but not TGF-beta 2. We conclude that TGF-beta 1 and -beta 2 expression in human skin is differentially regulated, and that their distribution is varied and complex.

Adult↗
PubMed1992

Transforming growth factor-beta differentially regulates the adhesiveness of normal and psoriatic dermal microvascular endothelial cells for peripheral blood mononuclear cells.

Lymphocytes adhere to dermal microvascular endothelial cells (DMEC) as the first step in their migration from the bloodstream into diseased skin. Psoriasis is characterized by an intense T-lymphocytic infiltrate in the dermis, which may be a consequence of the abnormal regulation of endothelial adhesiveness by cytokines released locally. In the present study, we investigated the effects of tumor necrosis factor-alpha (TNF), interleukin-1 (IL-1), IL-4, and transforming growth factor-beta 1 (TGF-beta) on the adhesiveness of DMEC isolated from psoriatic plaques or normal skin for human peripheral blood mononuclear cells (PBMC). The results showed that DMEC from both normal and psoriatic skin retain the capacity to adhere to 51Cr-labeled PBMC. Pretreatment of DMEC from normal skin with human recombinant IL-1 or TNF alone or in combination for 8 h significantly (p less than 0.01) enhanced their capacity to adhere to human PBMC. Similarly, treatment of normal DMEC with IL-4 also increased endothelial adhesiveness, although this cytokine required an incubation period of 24 h. In parallel studies, DMEC from psoriatic plaques were found to respond to the stimulatory effects of TNF, IL-1, and IL-4 in similar dose- and time-dependent manner. In contrast, although pretreatment of normal DMEC with TGF-beta (0.1 to 0.25 ng/ml) for 6 to 12 h significantly reduced (p less than 0.01) both the unstimulated and IL-1- and TNF-stimulated endothelial adhesiveness for normal PBMC, TGF-beta had no effect on the binding of unstimulated or cytokine-stimulated psoriatic DMEC to PBMC, even at concentrations as high as 2 ng/ml and incubation period of 36 h. These results suggest that cytokines stimulate the adhesiveness of DMEC through distinct pathways and provide evidence that TGF-beta may play an important regulatory role in the control of lymphocyte extravasation into normal skin. The altered responsiveness of psoriatic DMEC to TGF-beta may contribute to the intense dermal lymphocytic infiltrates in psoriasis.

Cell Adhesion↗
PubMed1992

Growth factors and chronic wounds: the need to understand the microenvironment.

The care of chronic wounds has become a major health issue in developed countries because of their increasingly elderly populations. There is hope that progress made in understanding and producing growth factors will lead to their successful use to induce faster and better healing of chronic wounds. This report will discuss growth factors in the context of their use in chronic wounds, and will focus on the importance of the wound microenvironment in determining the interactions between growth factors and wounds. We believe that a greater understanding of the chronic wound microenvironment will be of benefit in the optimal use of growth factors. In published studies, we have found that wound fluid taken from acute wounds stimulates fibroblast and endothelial cell proliferation, whereas fluid obtained from chronic non-healing wounds inhibits the growth of fibroblasts, endothelial cells, and keratinocytes. In this report, we describe the effect of these two types of wound fluid on the synthesis of extracellular matrix components. We hypothesize that the chronic wound microenvironment is generally non-conducive to cell growth, and that this may prevent a truly successful use of topical growth factors in chronic wounds. Novel approaches in the delivery of growth factors to wounds may be necessary to overcome these obstacles.

Cells, Cultured↗
PubMed1992

Topical use of human recombinant epidermal growth factor (h-EGF) in venous ulcers.

A great deal of interest has been focused recently on the potential use of synthetic polypeptide growth factors to stimulate healing of chronic wounds. In this pilot double-blind randomized study conducted at a single center, we used human recombinant epidermal growth factor (h-EGF) to treat 44 patients with venous ulceration of the lower extremities. An aqueous solution (10 micrograms/mL) of h-EGF was applied topically to the ulcers twice a day until healing occurred or for a maximum of 10 weeks. Patients were evaluated weekly for measurements of ulcer size and for the formation of granulation tissue suitable for grafting. Nine patients were excluded from efficacy evaluation because of protocol violations. Therefore, 35 patients (17 h-EGF, 18 placebo) were evaluable for efficacy, and 44 patients (22 h-EGF, 22 placebo) were available for safety. The median baseline ulcer size for all patients was 18.5 cm2, and was not significantly different between h-EGF and placebo group (12.9 cm2 versus 19.2 cm2, respectively, P = .27). By study end, six (35%) of h-EGF treated patients and two (11%) in the placebo group had healed completely (P = .10). Another 6 patients (2 of 17 h-EGF, 4 of 18 placebo; P = .50) developed healthy granulation tissue that was suitable for grafting. The median ulcer size reduction was 7% for h-EGF versus 3% for placebo per week (P = .29), and 73% versus 33% at study end (P = .32). No untoward side effects were related to the application of h-EGF. We conclude that topical application of h-EGF, in the dose and manner used in this study, was safe but failed to significantly enhance re-epithelialization of venous ulcers. However, a greater reduction in ulcer size and a larger number of healed ulcers with the use of h-EGF are encouraging results.

Administration, Topical↗
PubMed1992

The effects of occlusive dressings on the recruitment of mononuclear cells by endothelial binding into acute wounds.

Mononuclear cell infiltration is a characteristic feature of wounds and may play an important role in the healing process. We have previously shown that the recruitment of peripheral blood mononuclear cells into wounded skin is an active, dynamic, and regulated process mediated at least in part by specific interactions between mononuclear leukocytes and specialized dermal microvascular endothelial cells in the wounded skin. The purpose of this study was to investigate the capacity of dermal microvascular endothelial cells in wounds exposed to air or covered with occlusive dressings to promote the adhesion of monocytes and lymphocytes. The results showed that dermal microvascular endothelial cells in both air-exposed and occluded wounds were capable of supporting peripheral blood mononuclear cell and monocyte adherence. However, in comparison with air exposed wounds, the level of peripheral blood mononuclear cell binding was significantly higher in occluded biopsies obtained at 0 to 9, 12, 15, and 21 days after wounding. In addition, monocyte and peripheral blood mononuclear cells binding to occluded wounds peaked earlier than peripheral blood mononuclear cell binding to air exposed wounds. These studies provide evidence that differences in the kinetics and magnitude of mononuclear cell adherence may account at least in part for the beneficial effects of occlusive dressing on wound healing.

Animals↗
PubMed1992

Pericapillary fibrin cuffs in venous ulceration. Persistence with treatment and during ulcer healing.

A recent hypothesis suggests that venous hypertension leads to ulceration through the formation of pericapillary fibrin cuffs, which are presumed to impede the exchange of oxygen and other nutrients. In this report, we evaluated by direct immunofluorescence the presence of pericapillary fibrin at the edge of venous ulcers during the course of treatment with elastic compression. In an initial group of 23 patients studied at baseline, pericapillary fibrin cuffs were detected in 20 (91%) of 22 patients. The intensity of fibrin staining, rated blindly on a scale of 0 to 3, could not be correlated with several baseline parameters, including the clinical presence and extent of lipodermatosclerosis, ulcer size, venous recovery time, and transcutaneous oxygen measurements (TcPO2) taken next to the ulcer. Eleven of this initial group of 23 patients were randomly selected to receive elastic compression treatment, and were evaluated for the persistence of pericapillary fibrin at 60 and 120 days. Although a reduction (mean +/- SD = 50.2% +/- 25.7) in ulcer size occurred in 10 of the 11 patients, pericapillary fibrin was still present at the ulcer edge and with undiminished intensity. We conclude that pericapillary fibrin cuffs in venous ulcers persist with compression treatment and in spite of healing, and are unlikely to be directly related to the development of ulceration.

Adult↗
PubMed1991

Stanozolol in treatment of leg ulcers due to cryofibrinogenaemia.

Five consecutive patients with cryofibrinogenaemia in association with painful leg ulcers and intravascular dermal thrombi were treated with stanozolol, an androgenic steroid with fibrinolytic properties. In all patients treatment was followed by rapid and striking pain relief and healing of the ulcers. Cryofibrinogenaemia was not detected on subsequent laboratory evaluation, and dermal intravascular thrombi had resolved on repeat histological examination.

Adult↗
PubMed1991

Human wound fluid from acute wounds stimulates fibroblast and endothelial cell growth.

One proposed mechanism for the beneficial effect of occlusive dressings on healing is the maintenance of contact between the wound bed and accumulated wound fluid, which is thought to contain growth stimulatory substances. We have examined the effect of human wound fluid on the in vitro growth of human dermal fibroblasts and umbilical vein endothelial cells. Acute wound fluid was collected from six patients undergoing split-thickness skin grafting. The acute wound fluid was sterilely collected daily from underneath a vapor-permeable membrane applied to the donor site and changed every 24 hours for 3 days postoperatively. After seeding in optimal growth media (control) on day 0, cultures of human dermal fibroblasts and umbilical vein endothelial cells were supplemented with or without acute wound fluid on the next day (day 1) and on day 3. As determined by cell counts, 2% acute wound fluid stimulated the growth of human dermal fibroblasts (p less than 0.05) and umbilical vein endothelial cells (p less than 0.01) when these cells were cultured in 2% fetal bovine serum and endothelial growth medium, respectively. Wound fluid from postoperative days 1 or 3 caused the same level of stimulation. The addition of an anti-platelet-derived growth factor antibody to wound fluid resulted in a 45% mean reduction in its stimulatory effect on fibroblast growth (p less than 0.02), suggesting that platelet-derived growth factor contributes to the observed effect.(ABSTRACT TRUNCATED AT 250 WORDS)

Cell Count↗
PubMed1991

Proliferation and collagen synthesis by human dermal fibroblasts cultured from different body sites.

Distal areas in systemic sclerosis (scleroderma), such as the dorsal skin of the hand are more frequently involved and more indurated than proximal areas. On the contrary, the observation often made after surgical excision or trauma is that distal body areas heal more slowly than proximal areas. A possible explanation may be that dermal fibroblasts from distal body parts are more capable, when stimulated, to synthesize greater or lesser amounts of collagen and proliferate at different rates than dermal fibroblasts from more proximal skin. In this study, cultures of dermal fibroblasts from three different body sites (arm, forearm, and hand) of healthy volunteers were investigated for their proliferative activity and collagen synthesis after stimulation in 3% or 10% fetal bovine serum. No significant differences were observed in cell proliferation or in the relative or absolute collagen synthesis by fibroblasts cultured from the hand, forearm or upper arm. We conclude that other in vivo factors are responsible for the observed differences in fibrosis and healing at different body sites. Moreover, if clonal expansion of different fibroblast phenotypes occurs in these physiologic or disease states, it must be of a magnitude that overcomes the fundamental proliferative and biosynthetic baseline.

Adult↗
PubMed1991

Fibrin and fibrinogen-related antigens in systemic sclerosis (scleroderma)

Abnormalities in fibrin deposition are implicated in the pathogenesis of vascular occlusion in systemic sclerosis. We have used a technique that involves electrophoresis and densitometric analysis of captured fibrin- and fibrinogen-related antigens to measure the concentration of the individual fibrin and fibrinogen degradation products in 13 patients with systemic sclerosis and in 15 healthy control subjects. As a group, patients with systemic sclerosis had markedly elevated levels of total fibrin-related antigen (p = 0.0007) and D-dimer (p = 0.0004), the terminal degradation product of cross-linked fibrin. The levels of fibrin monomer, an intermediate product in the conversion of fibrinogen to cross-linked fibrin, and of D-monomer, a terminal breakdown fragment of fibrinogen and fibrin monomer, were also elevated (p less than 0.005). We conclude that patients with systemic sclerosis have evidence of enhanced fibrin formation and degradation.

Adult↗
PubMed1991

Transforming growth factor-beta regulates the adhesive interactions between mononuclear cells and microvascular endothelium.

Adhesion of leukocytes to the vascular endothelium is essential for the movements of cells from the bloodstream into inflammatory sites. In the present study, dermal microvascular endothelial cells (DMEC) isolated from normal porcine skin retained the capacity to adhere 51Cr-labeled porcine peripheral blood mononuclear cells (PBMC), nylon-wool-purified T cells, and isolated monocytes. Transforming growth factor-beta 1 (TGF-beta) decreased the capacities of DMEC to support the adhesion of these cells in a dose-dependent manner. Maximal inhibition was observed with a TGF-beta dose of 0.25 ng/ml and an incubation time of 6-12 h. TGF-beta did not affect the morphology of DMEC and had no adverse effect on the viability of the treated cells. The blocking effects of TGF-beta on PBMC adhesion to DMEC was neutralized by a polyclonal turkey anti-TGF-beta antiserum but not by control turkey serum. Although pretreatment of PBMC with TGF-beta decreased the capacity of these cells to adhere to normal DMEC monolayers, kinetic studies demonstrated that these effects required between 4 and 8 h incubation time. In addition, preincubation of DMEC with TGF-beta completely blocked their response to the stimulating effects of TNF-alpha, IL-1-beta, or both cytokines. Furthermore, TGF-beta also abrogated the enhanced adhesiveness of DMEC pretreated with TNF-alpha and IL-1-beta. These findings suggest that TGF-beta may play an important role in the down-regulation of inflammatory responses by decreasing vascular endothelial adhesiveness for mononuclear cells and monocytes.

Animals↗
PubMed1991

Hypoxia upregulates the synthesis of TGF-beta 1 by human dermal fibroblasts.

In this report, we have investigated the secretion and synthesis of transforming growth factor-beta 1 (TGF-beta 1) by human dermal fibroblast cultures in response to hypoxia (2% oxygen), and have compared it to standard oxygen culture conditions (15% oxygen at the cell surface). Sandwich enzyme-linked immunosorbent assay (SELISA) showed a selective and progressive increase in secretion of the TGF-beta 1 isoform in response to hypoxia, up to ninefold after cultures were exposed to low oxygen for 72 h; TGF-beta 2 peptide levels were not increased. We then investigated the transcriptional regulation of the TGF-beta 1 gene in response to low and standard oxygen tensions. In the first 24-48 h, TGF-beta 1 mRNA levels decreased steadily in both oxygen environments. This mRNA decline continued for up to 72 h in standard oxygen but not in cultures exposed to low oxygen tension. At 72 h, steady-state TGF-beta 1 mRNA levels were 8 times greater in low compared to standard oxygen, and this increase was reversible upon re-exposure of fibroblast cultures to standard oxygen tension for 24 h. Elevated TGF-beta 1 m-RNA levels in both low and standard oxygen declined steadily and with the same half-life after the addition of actinomycin D, suggesting that hypoxia increased TGF-beta 1 transcription rather than mRNA stability. We conclude that low oxygen tension upregulates the synthesis of TGF-beta 1 by human dermal fibroblasts, and leads to increased secretion of this peptide.

Cell Hypoxia↗
PubMed1991

The effect of topical nitroglycerin on transcutaneous oxygen.

The use of topical nitroglycerin has been reported to aid the healing of chronic skin ulcers. In this study, the effect of 2% nitroglycerin ointment on transcutaneous oxygen pressure (TcPO2) was investigated in skin adjacent to the area of ointment application. Topical nitroglycerin caused a two-fivefold decrease in TcPO2 in skin next to or up to 9 cm away from the site of application of the ointment.

Administration, Topical↗
PubMed1991

Heterogeneity in oxygen diffusion around venous ulcers.

The pathogenesis of venous ulceration is thought to involve the formation of fibrin cuffs around dermal capillaries. Consistent with a barrier effect of fibrin, it has been shown that the dermal diffusion of oxygen, as measured by transcutaneous oxygen pressure (TcPO2), is decreased in limbs affected by venous ulcer. However, it is unknown whether oxygen diffusion around the perimeter of venous ulcers is uniformly affected. In this study, we investigated TcPO2 values at four different quadrants around the ulcers of 14 patients, the contralateral leg of five patients with unilateral ulcers, and the leg of six normal individuals. These values were also compared to TcPO2 measurements at the chest. Our results indicate that, whereas TcPO2 values in limbs affected by venous ulcers are much lower than normal, there is a great deal of variability in oxygen diffusion around individual ulcers. These findings may represent a heterogeneity in the disease process affecting the leg.

Adult↗
PubMed1991

Recruitment of mononuclear cells into wounded skin: mechanism and modulation.

In conclusion, we have shown that the development of specialized endothelium that supports lymphocyte and monocyte adherence may be a common biologic event associated with tissue injury or disease processes in the skin. We have shown that the adherence process is potentially regulated by cytokines that are secreted by infiltrating mononuclear cells. Studies are now in progress to identify the putative endothelial ligands, their interactions with the receptors and the factors that lead to the expression of the adhesion molecules.

Animals↗