Wound microenvironment plays a major role in the process of wound healing. It contains various external and internal factors that participate in wound pathophysiology. The pH is an important factor that influences wound healing by changing throughout the healing process. Several previous studies have investigated the role of pH in relation to pathogens but studies concentrating on the effects of pH on wound healing itself are inconclusive. The purpose of this study was to comprehensively and in a controlled fashion investigate the effect of pH on wound healing by studying its effect on human primary keratinocyte and fibroblast function in vitro and on wound healing in vivo. In vitro, primary human keratinocytes and fibroblasts were cultured in different levels of pH (5.5-12.5) and the effect on cell viability, proliferation, and migration was studied. A rat full-thickness wound model was used to investigate the effect of pH (5.5-9.5) on wound healing in vivo. The effect of pH on inflammation was monitored by measuring IL-1 α concentrations from wounds and cell cultures exposed to different pH environments. Our results showed that both skin cell types tolerated wide range of pH very well. They further demonstrated that both acidic and alkaline environments decelerated cell migration in comparison to neutral environments and interestingly alkaline conditions significantly enhanced cell proliferation. Results from the in vivo experiments indicated that a prolonged, strongly acidic wound environment prevents both wound closure and reepithelialization while a prolonged alkaline environment did not have any negative impact on wound closure or reepithelialization. Separately, both in vitro and in vivo studies showed that prolonged acidic conditions significantly increased the expression of IL-1 α in fibroblast cultures and in wound fluid, whereas prolonged alkaline conditions did not result in elevated amounts of IL-1 α.
This study confirms the presence of distinct subcutaneous fat compartments and provides evidence for an individual behavior when soft-tissue fillers are applied: inferior displacement of the superficial nasolabial, middle cheek, and jowl compartments, in contrast to an increase in volume without displacement (i.e., an increase in projection) of the medial cheek, lateral cheek, and both superficial temporal compartments.
Background: Injection of soft-tissue fillers into the facial fat compartments is frequently performed to ameliorate the signs of facial aging. This study was designed to investigate the functional anatomy of the deep facial fat compartments and to provide information on the effects of injected material in relation to age and gender differences. Methods: Forty fresh frozen cephalic specimens of 17 male and 23 female Caucasian body donors (mean age, 76.9 ± 13.1 years; mean body mass index, 23.6 ± 5.3 kg/m2) were investigated. Computed tomographic and magnetic resonance imaging procedures were carried out using colored contrast-enhanced materials with rheologic properties similar to commercially available soft-tissue fillers. Anatomical dissections were performed to guide conclusions. Results: No statistically significant influences of age or gender were detected in the investigated sample. Increased amounts of injected contrast agent did not correlate with inferior displacement of the material in any of the investigated compartments: deep pyriform, deep medial cheek, deep lateral cheek, deep nasolabial (located within the premaxillary space), and the medial and lateral sub–orbicularis oculi fat. Conclusions: Increasing volume in the deep midfacial fat compartments did not cause inferior displacement of the injected material. This underscores the role of deep soft-tissue filler injections (i.e., in contact with the bone) in providing support for overlying structures and resulting in anterior projection.
The results of this study support the use of cannula versus needle and the proximal-to-distal fanning technique. The underlying anatomy supports the positioning of the material into the subdermal space, which can be identified less than 1 mm deep to the skin surface, and is termed the dorsal superficial lamina.
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