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Results for “Skin Window Technique”

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At least 271 records · Page 15Linked to original sources
PubMed2000

Initial stages of tumor cell-induced angiogenesis: evaluation via skin window chambers in rodent models.

BACKGROUND: There is a paucity of information about events that follow immediately after tumor cells are triggered to initiate the process of angiogenesis (the formation of new blood vessels). Such information is relevant to the issue of when micrometastases vascularize and has implications for the accessibility of micrometastases to various treatments. In this study, we attempted to monitor events at the initiation of angiogenesis at the earliest possible stage of tumor growth in vivo. METHODS: Two different rodent mammary tumor cell lines, R3230Ac from the Fischer 344 rat and 4T1 from the BALB/c mouse, were stably transfected with a gene that encodes an enhanced version of green fluorescence protein (GFP). GFP-labeled R3230Ac or 4T1 cells (about 20-50 cells) were implanted into dorsal skinfold window chambers of Fischer 344 rats or BALB/c mice, respectively. Tumor angiogenesis was then monitored serially and noninvasively for up to 4 weeks. RESULTS: Clear evidence of modification of the host vasculature was observed when tumor mass reached approximately 60-80 cells, and functional new blood vessels were seen when tumor mass reached roughly 100-300 cells. Individual tumor cells exhibited a chemotaxis-like growth pattern toward the pre-existing host vasculature. When ex-flk1 (a soluble, truncated vascular endothelial cell growth factor receptor protein known to be antiangiogenic) was injected with the tumor cells, the initial angiogenic and tumor growth activities were inhibited considerably, indicating that angiogenesis inhibitors may halt tumor growth even before the onset of angiogenesis. CONCLUSION: Angiogenesis induced by tumor cells after implantation in the host begins at a very early stage, i.e., when the tumor mass contains roughly 100-300 cells. Identification of chemotactic signals that initiate tumor cell migration toward the existing vasculature may provide valuable targets for preventing tumor progression and/or metastases.

Animals↗
PubMed1993

Decreased polymorphonuclear leukocyte exudation in critically ill anergic patients associated with increased adhesion receptor expression.

OBJECTIVE: To determine the mechanism for the reduced polymorphonuclear leukocyte exudation in critically ill anergic patients. DESIGN: Prospective consecutive patient study. SETTING: Tertiary care surgical intensive care unit. PATIENTS: Eighteen patients with intra-abdominal injections were studied. INTERVENTIONS: Critically ill patients were stratified based on their delayed type hypersensitivity response to ubiquitous antigens. Polymorphonuclear leukocytes were isolated from blood and from exudate blister type skin windows. Adhesion and chemotactic surface receptors were measured, as was cytokine content and chemoattraction capacity of skin window fluid for control neutrophils. MEASUREMENTS AND MAIN RESULTS: Circulating neutrophils from anergic patients have increased CR3 adherence receptors compared with those neutrophils from reactive patients. f-met-leu-phe receptors are equal in number and C5a receptors are either significantly reduced in number or occupied with ligand. This same receptor pattern is maintained after neutrophil exudation in both patient groups. Serum and skin window fluid from anergic patients attracted less neutrophils in vitro and in vivo. CONCLUSIONS: These data suggest two possible mechanisms for the reduced neutrophil delivery of critically ill anergic patients: a receptor-mediated increased adherence to vascular endothelium preventing diapedesis; reduced chemo-attraction potential of serum, and possibly, exudate fluid.

Adult↗
PubMedDate not supplied

Burn-induced alterations in vasoactive function of the peripheral cutaneous microcirculation.

Alterations in the cutaneous vasomotion function caused by scald burns to a large area on the flank were observed and quantified in a dorsal skin flap window with a hamster model. Subsequent to chronic implantation of the window chamber to provide direct microscopic observation of blood flow for an entire thickness of skin, control measurements of vasoactivity in a defined network of arterioles were taken by means of a digital video image splitter over a period of several days. A 100 degrees C, 5-second water scald was then effected over 17% to 55% of the total body surface area, and the vasoactivity was remeasured in the targeted set of sites at serial time intervals for 2 to 4 days. Data were acquired directly into a computer and analyzed for both the magnitude and time pattern of diameter fluctuations during 3-minute observation periods. Average and standard deviations of diameters were computed, and the Prony power spectral analysis method was applied to identify the presence and strength of fluctuation frequencies. In general, vasomotion was suppressed for several hours subsequent to the burn, and the activity was dominated by much slower contractions than control. No direction of vessel diameter changes prevailed uniformly throughout the peripheral microcirculation. Large alternate constrictions and dilations were also observed for some arteriolar and venular components, but others exhibited no significant change at all. The incidence and magnitude of peripheral microvascular response was proportional to the size of the injured area.

Anesthesia, Inhalation↗
PubMedDate not supplied

Local macromolecular extravasation in thermal burns quantified by fluorescent video microscopy and computer vision.

A dorsal skin flap chamber model was developed for analysis of the microvascular response to moderate intensity local thermal burns. Fluorescein isothiocyanate tagged 70,000 d dextran was introduced to visualize the extravasation and interstitial transport of macromolecules at the burn site. Contact burns 0.5 cm in diameter were affected by touching a thermostated metal rod onto the exposed epidermal side of the chamber preparation. All burns were of 5-second duration at temperatures between 55 degrees C and 70 degrees C. Postburn leakage of the fluorescein-labeled probed was monitored at numerous sites in the preparation on a fluorescent microscope equipped with a low-light-level intensified silicon intensified target video camera and recorded on tape for subsequent quantitative analysis. Selected scenes were digitized and subjected to a sequence of computer-image processing operations to extract quantitative information about the concentration distribution and net accumulation of dextran in the interstitial space as a function of postburn time. A diffusion model based on cylindrical geometry was fit to the concentration profile data at each site analyzed, and an apparent diffusion coefficient describing the interstitial transport process was determined. The interstitial transport increased with burn temperature up to a threshold of 70 degrees C, where other factors resulted in significant reduction in the loss of fluorescent macromolecule from the vasculature.

Animals↗
PubMed2004

Microhemodynamic and cellular mechanisms of activated protein C action during endotoxemia.

OBJECTIVE: To characterize microcirculatory actions of activated protein C in an endotoxemia rodent model that allows in vivo studies of microvascular inflammation and perfusion dysfunction. DESIGN: Animal study using intravital microscopy. SETTING: Animal research facility. SUBJECTS: Male Syrian golden hamsters, 6-8 wks old with a body weight of 60-80 g. INTERVENTIONS: In skinfold preparations, endotoxemia was induced by intravenous administration of 2 mg/kg endotoxin (lipopolysaccharide, Escherichia coli). Intravital microscopy allowed quantitative analysis of arteriolar and venular leukocyte adhesion and functional capillary density (cm) that served as a measure of microvascular perfusion failure. Activated protein C (APC group, n = 8, 24 microg/kg intravenously) was substituted continuously during 8 hrs after lipopolysaccharide, whereas endotoxemic buffer-treated animals (control, n = 7) served as controls. MEASUREMENTS AND MAIN RESULTS: Lipopolysaccharide increased leukocyte adhesion and decreased functional capillary density to 50% of baseline values (p <.01 vs. baseline). Activated protein C treatment inhibited (p <.05) lipopolysaccharide-mediated leukocytic response and attenuated (p <.05) endotoxic perfusion failure in nutritive capillaries. CONCLUSIONS: Activated protein C-induced protection from lipopolysaccharide-mediated microcirculatory dysfunction was characterized in vivo for the first time. The impressive modification of leukocyte cross-talk indicates systemic anti-inflammatory activated protein C effects on leukocytes and the endothelium, subsequently improving capillary perfusion. These actions could represent the in vivo mechanism of activated protein C interactions observed in patients with severe sepsis.

Animals↗
PubMed2003

Wound fluid bacterial levels exceed tissue bacterial counts in controlled porcine partial-thickness burn infections.

In the present study, an established controlled burn wound model was used to test the hypothesis that controlled surface contamination with is capable of generating a noninvasive method for the creation of a reproducible deep tissue burn wound infection. Using a liquid tight-wound chamber in Yorkshire pigs, partial-thickness burns were inoculated with saline-immersed for 24 hours. Noninoculated burns and unwounded skin immersed in normal saline served as controls. Bacterial cultures of wound fluid were performed daily, and tissue biopsies for bacteriological and histological evaluations were performed on days 1, 3, and 5. was only recovered from -inoculated wounds (tissue and fluid), whereas all controls contained endogenous only. The number of colony-forming units per gram of wound tissue did not correlate with the bacterial counts found in the overlying wound fluid for any wounds. Fluid counts were consistently higher than tissue counts by two logs. -inoculated wounds showed three times deeper tissue destruction than control wounds. Obtaining consistently deep tissue colonization without cross-contamination among wounds, this study introduces a noninvasive model for controlled burn wound infection suitable for future investigations regarding the efficacy of topical antibiotic wound treatment in experimental burns.

Animals↗
PubMed1985

Leukotriene- and histamine-induced increases in vascular permeability and interstitial transport in the skin.

The aim of the present study was to investigate the edema induced by leukotriene D4 (LTD4). Edema is the gross effect of increased blood flow and capillary permeability. Our objective was to elucidate the effect of LTD4 on edema generation without the influence of the concomitantly increased blood flow induced by this potent vasodilator. A new method was outlined measuring the exudation through skin windows of a macromolecular tracer [( 131I]albumin) and a micromolecular tracer [( 99Tc]pertechnetat). Exudation of [131I]albumin is a function of enhanced vascular permeability and interstitial transport and blood flow, whereas that of [99Tc] pertechnetat is mainly a function of blood flow. Thus a ratio of the 2 exudate measurements gives a specific estimate of the changes in vascular permeability and interstitial transport. Histamine was employed to establish the method. A dose-response relation was found for histamine in the dose range of 10(-4) to 10(-7) M. The effect of 10(-5) M LTD4 on vascular permeability and interstitial transport of macromolecules was indistinguishable from that of histamine in the same concentration. This property together with their well-known vasodilatory capabilities indicate that the leukotrienes of the slow-reacting substance of anaphylaxis may play a role in the vascular changes in the allergic-inflammatory reaction.

Adult↗
PubMed1979

Transcutaneous leukocyte migration in vivo: cellular kinetics, platelet and C5a dependent activity.

A simple quantitative method for the measurement of leukotaxis in vivo is described. Duplicate skin chambers are placed over tape-stripped skin with 50% autologous serum--50% Hank's balanced salt solution as the attractant. Neutrophils predominate throughout 24 hr in this method with no change to mononuclear cells. A recommended modification of our original method is that chambers are sampled and removed after 8 hr rather than 24 hr since the majority of leukocyte migration occurs within the first 8 hr. Analysis of serum factors showed that heat-inactivation of the serum (56degreesC for 30 min) had no effect. However, depleting platelets or C5 from the serum removed approximately 90% of chemotactic activity for human neutrophils in vivo. Platelets, presumably through activity of their granules, enzymatically cleaves C5a from C5 in plasma. We conclude that C5a, after cleavage from C5, accounts for the majority of chemattractant activity in vivo.

Blood Platelets↗