Seng-Teik Lee

Protective effects of curcumin against oxidative damage on skin cells in vitro: its implication for wound healing.

BACKGROUND Curcumin, isolated from turmeric, has been known to possess many pharmacologic properties. It has been proven to exhibit remarkable anticarcinogenic, anti-inflammatory, and antioxidant properties. Turmeric curcumin may be a good potential agent for wound healing. METHODS To further understand its therapeutic mechanisms on wound healing, the antioxidant effects of curcumin on hydrogen peroxide (H2O2) and hypoxanthine-xanthine oxidase induced damage to cultured human keratinocytes and fibroblasts were investigated. Cell viability was assessed by colorimetric assay and quantification of lactate dehydrogenase release. RESULTS Exposure of human keratinocytes to curcumin at 10 microg/mL showed significant protective effect against hydrogen peroxide. Interestingly, exposure of human dermal fibroblasts to curcumin at 2.5 microg/mL showed significant protective effects against hydrogen peroxide. No protective effects of curcumin on either fibroblasts or keratinocytes against hypoxanthine-xanthine oxidase induced damage were found in our present studies. CONCLUSION The findings indicate that curcumin indeed possessed powerful inhibition against hydrogen peroxide damage in human keratinocytes and fibroblasts.

Anatomic basis of cleft palate and velopharyngeal surgery: implications from a fresh cadaveric study.

&NA; The purpose of this investigation was to apply the findings of an anatomic study of the levator veli palatini, palatopharyngeus, and superior constrictor muscles in 18 fresh cadaveric specimens of normal adults to analyze current controversies in velopharyngeal function and cleft palate surgery. The levator veli palatini was observed to form a muscular sling, suspending the velum from the cranial base. Its fibers occupied the middle 50 percent of the velum, lying in transverse orientation and without significant overlap across the midline. It is well placed to function as the prime mover in the velar component of velopharyngeal closure. The velar component of the palatopharyngeus consisted of two heads clasping the levator and inserting into the latter just short of the midline. Its pharyngeal component inserted into the superior constrictor in the lateral and posterior pharyngeal walls. Together, these two muscles formed a sphincter around the velopharyngeal port, suggesting that both muscles are involved in the pharyngeal component of velopharyngeal closure. Based on the premise that the goal of palatoplasty is to restore normal anatomy, the intravelar veloplasty has a sound basis, and theoretically improves both velar and pharyngeal wall function because it corrects the dysmorphology of both the levator and palatopharyngeus. Although the Furlow palatoplasty also reorients these velar muscles correctly in the transverse position, the resulting overlap of the levator and palatopharyngeus across the midline is morphologically abnormal. In addition, the use of large Z‐plasty flaps in wide clefts may cause excessive lateral tension, increasing the risk of fistula formation and causing an impairment of velar stretch capacity. The raising of a vertical pharyngeal flap divides the fibers of the superior constrictor and has the potential to impair pharyngeal wall function. The sphincter pharyngoplasty interferes less with pharyngeal wall anatomy. The potential for an obstructive outcome seems to be related to the use of wide, long flaps and a tight, overlapping type of flap inset. In addition, the level of flap inset is important: an inset at the level of the uvula has the greatest risk of causing obstruction, whereas a higher inset at the level of attempted velopharyngeal closure seems to provide the best opportunity for achieving velopharyngeal competence while avoiding hyponasality and obstruction.

Suppression of transforming growth factor beta/smad signaling in keloid-derived fibroblasts by quercetin: implications for the treatment of excessive scars.

BACKGROUND Keloids are characterized by abnormal proliferation and overproduction of extracellular matrix. Quercetin, a dietary compound, has strong antioxidant and anticancer properties. Previous studies by the authors have shown that quercetin inhibits fibroblast proliferation, collagen production, and contraction of keloid and hypertrophic scar-derived fibroblasts. Quercetin also blocks the signal transduction of insulin-like growth factor-1 in keloid fibroblasts. This study assessed the effects of quercetin on the transforming growth factor (TGF)-beta/Smad-signaling pathway in keloid-derived fibroblasts, which may be an important biologic mechanism of this proliferative scarring. METHODS Keloid fibroblasts were isolated from keloid tissue specimens. Cells were treated with quercetin at different concentrations, then harvested, and subjected to immunoblotting analysis. RESULTS Quercetin significantly inhibited the expression of TGF-beta receptors 1 and 2 in keloid fibroblasts at three concentrations (low, medium, and high). Quercetin also strongly suppressed the basal expression of Smad2, Smad3, and Smad4 as well as the phosphorylation of Smad2 and Smad3 and the formation of the Smad2-Smad3-Smad4 complex. CONCLUSIONS Taken together, these data suggest that quercetin effectively blocks the TGF-beta/Smad-signaling pathway in keloid fibroblasts. These data indicate that quercetin-based therapies for keloids should be investigated further.

A fresh cadaveric study of the paratubal muscles: implications for eustachian tube function in cleft palate.

&NA; The aims of this anatomic investigation were to examine the levator veli palatini, tensor veli palatini, and salpingopharyngeus muscles in relation to normal eustachian tube function and to analyze the clinical implications of these data for tubal physiology in cleft palate individuals. Detailed dissections under 3.2x loupe magnification were conducted on the paratubal muscles of 15 fresh human adult cadaveric head specimens, paying particular attention to their cranial base anatomy. Each half of the cadaveric heads was examined separately, giving a sample size of 30. The cranial base origin of the levator veli palatini was the junction of the cartilaginous and bony parts of the eustachian tube. Contrary to statements in the existing literature, it had no origin from the quadrate area of the petrous temporal bone. In its path toward the velum, it was related inferiorly and lay almost parallel to the tube. The tensor veli palatini originated from the scaphoid fossa of the sphenoid bone and the tube. In contrast to previous descriptions, it was found to consist of a single sheet of muscle with no bilaminar structure. Its axis was oblique to that of the tube. The salpingopharyngeus was a slender muscle attached to the posteroinferior aspect of the pharyngeal end of the tube. It inserted into the palatopharyngeus inferiorly. These morphologic characteristics and anatomic relationships suggest that (1) the levator veli palatini opens the eustachian tube by isotonic contraction that results in displacement of the medial tubal cartilage and the tubal membrane, (2) the tensor veli palatini opens the the tube directly by traction on the lateral tubal membrane and indirectly by rotation of the medial tubal cartilage by means of traction on the lateral tubal cartilage, (3) because of its consistently small size, the salpingopharyngeus is probably functionally the least important of the paratubal muscles, (4) the levator veli palatini is unable to cause tubal dilatation in cleft palate because it can only contract isometrically, and (5) tensor veli palatini function is probably unaffected by clefting. However, its mechanism of action may be disrupted iatrogenically by complete hamular fracture or division of its tendon. (Plast. Reconstr. Surg. 100: 833, 1997.)

Synchronous Activation of ERK and Phosphatidylinositol 3-Kinase Pathways Is Required for Collagen and Extracellular Matrix Production in Keloids

Keloid fibroproliferation appears to be influenced by epithelial-mesenchymal interactions between keloid keratinocytes (KKs) and keloid fibroblasts (KFs). Keloid and normal fibroblasts exhibit accelerated proliferation and collagen I and III production in co-culture with KKs compared with single cell culture or co-culture with normal keratinocytes. ERK and phosphatidylinositol 3-kinase (PI3K) pathway activation has been observed in excessively proliferating KFs in co-culture with KKs. We hypothesized that ERK and PI3K pathways might be involved in collagen and extracellular matrix production in KFs. To test our hypothesis, four samples of KFs were co-cultured in defined serum-free medium with KKs for 2–5 days. KF cell lysate was subjected to Western blot analysis. Compared with KF single cell culture, phospho-ERK1/2 and downstream phospho-Elk-1 showed up-regulation in the co-culture groups, as did phospho-PI3K and phospho-Akt-1, indicating ERK and PI3K pathway activation. Western blotting of the conditioned medium demonstrated increased collagen I–III, laminin β2, and fibronectin levels. Addition of the MEK1/2-specific inhibitor U0126 or the PI3K-specific inhibitor LY294002 (but not p38 kinase and JNK inhibitors) completely nullified collagen I–III production and significantly decreased laminin β2 and fibronectin secretion. In the presence of the MEK1/2 or PI3K inhibitor, fibronectin demonstrated changes in molecular mass reflected by faster in-gel migration. These data strongly suggest that synchronous activation of both the ERK and PI3K pathways is essential for collagen I–III and laminin β2 production. These pathways additionally appear to affect the side chain attachments of fibronectin. Modulation of these pathways may suggest a direction for keloid therapy.

dietary Compounds Inhibit Proliferation and Contraction of Keloid and Hypertrophic Scar-derived Fibroblasts In Vitro : therapeutic Implication for Excessive Scarring

BACKGROUND Keloid and hypertrophic scars commonly occur after injuries. Overproliferation of fibroblasts, overproduction of collagen, and contraction characterize these pathologic scars. Current treatment of excessive scars with intralesional corticosteroid injections used individually or in combination with other methods often have unsatisfactory outcome, frustrating both the patient and the clinician. The phytochemical compounds are well known as potential anticancer agents. We have investigated the inhibitory effects of compounds on keloid fibroblasts (KF) and hypertrophic scar-derived fibroblasts (HSF). METHODS Fibroblasts were cultured from nontreated earlobe keloids and burn hypertrophic scars. Ten compounds (three hydroxybenzoic and four hydroxycinnamic acid derivatives, two flavonols [quercetin and kaempferol], and turmeric curcumin) were tested with fibroblasts. The inhibitory effects of compounds on fibroblasts was assessed by proliferation assays, fibroblast-populated collagen lattice (FPCL) contraction, and electron microscopy. RESULTS The phytochemicals significantly inhibited KF and HSF proliferation in a dose- and time-dependent manner. In the hydroxybenzoic and flavonol groups, increasing inhibitory effects seemed to depend on increasing numbers of hydroxyl groups in their chemical structures. This phenomenon was not observed in the hydroxycinnamic acid group. The phytochemicals inhibited fibroblast proliferation by inducing cell growth arrest but not apoptosis. The reversibility of growth inhibition occurred when the compounds were removed from the culture and fresh media was replaced. Slower reversibility of growth inhibition was observed in the groups treated with quercetin, chlorogenic acid, or curcumin. The compounds quercetin, gallic acid, protocatechuic acid, and chlorogenic acid were the strongest inhibitors of FPLC contraction by HTFs. When the compounds were washed out of the lattices and replaced by fresh medium, the FPCL contraction was resumed. The resumption of FPCL contraction was slowest in the quercetin-treated group, indicating again the strong inhibitory effect of quercetin. CONCLUSION From this in vitro study, quercetin seemed to have good potent effects to inhibit proliferation and contraction of excessive scar-derived fibroblasts.

Anatomic basis of safe percutaneous subclavian venous catheterization.

BACKGROUND The technique of percutaneous catheterization of the subclavian vein by the infraclavicular approach is dependent on the location of the subclavian vein in relation to the clavicle. The purpose of this study was to analyze the anatomic relationship between these two structures and how it is influenced by changes in shoulder positioning. METHODS Dissections of the infraclavicular region were performed in seven fresh cadavers and linear measurements made to determine the extent of overlap between the vein and the clavicle in different shoulder positions. RESULTS When the shoulder was in neutral position, the subclavian vein was overlapped by the medial third or more of the clavicle and this segment of bone was able to serve as a landmark for the vein. However, shoulder elevation displaced the clavicle cephalad and reduced the degree of overlap. Mild shoulder retraction increased the area of contact between the vein and the undersurface of the clavicle, whereas protraction lifted the clavicle off the vein. CONCLUSION Infraclavicular subclavian venipuncture should be performed with shoulders in a neutral position and also in slight retraction. An appreciation of the anatomic relationship between the clavicle and the subclavian vein is the key to successful execution of this technique.

Differences in collagen production between normal and keloid-derived fibroblasts in serum-media co-culture with keloid-derived keratinocytes

Keloids are characterized by the deposition of excessive extracellular-matrix collagen by abnormal fibroblasts in response to cutaneous injury. Studies to date have largely concentrated on the role of the keloid fibroblast in the pathogenesis of this lesion. Recent studies have highlighted the important concept of epithelial-mesenchymal interactions in normal skin biology. Extrapolating this to keloids in two recent serum-free in vitro studies, we demonstrated increased growth and proliferation, as well as induction of keloid-like collagen secretory characteristics in normal fibroblasts co-cultured with keloid-derived keratinocytes. Most fibroblast culture work to date has been performed in nutrient and growth factor-rich serum media. To investigate how a serum co-culture system might influence epithelial-mesenchymal interactions, [3H] proline incorporation was examined in normal and keloid fibroblasts co-cultured in serum with keratinocytes derived either from normal skin or keloid tissue. Results showed increased [3H] proline incorporation when normal fibroblasts were co-cultured with keloid keratinocytes, which was significantly increased when keloid fibroblasts were co-cultured with keloid keratinocytes. Taken with previous results, this study demonstrates a good correlation between both serum and serum-free co-culture systems, and supports the significance of epithelial-mesenchymal interactions in keloid pathogenesis.

Structure of the Musculus Uvulae: Functional and Surgical Implications of an Anatomic Study

OBJECTIVE The role of the musculus uvulae in velopharyngeal function, its morphologic status in cleft palate, and its fate in palatoplasty procedures are subjects of controversy. The aims of this investigation were to re-examine this velar muscle to clarify its anatomic characteristics, to analyze its role in speech physiology, and to study the surgical implications of this information for cleft palate repair. METHODS Its attachments, morphology, and relations were examined in 18 fresh human adult cadavers by detailed dissection under 3.2x magnification and light microscopy. RESULTS The musculus uvulae was observed to be a paired midline muscle extending between the tensor aponeurosis anteriorly and the base of the uvula posteriorly along the nasal aspect of the velum. It had no attachments to the hard palate. CONCLUSIONS These findings suggest that its action is to increase midline bulk on the nasal aspect of the velum, thus contributing to the levator eminence. It may also have an extensor effect on the nasal aspect of the velum, displacing it toward the posterior pharyngeal wall. Both of these actions would serve to maximize midline velopharyngeal contact. One clinical application of this anatomic information is that the muscle should be preserved in the dissection performed during intravelar veloplasty. Furthermore, it should be recognized that the musculus uvulae is invariably divided and reoriented incorrectly in the Furlow double opposing Z-plasty.

Suppression of insulin-like growth factor signalling pathway and collagen expression in keloid-derived fibroblasts by quercetin: its therapeutic potential use in the treatment and/or prevention of keloids

Summary Background Keloids are characterized by abnormal proliferation of fibroblasts and overproduction of collagen. Insulin‐like growth factor (IGF)‐I is mitogenic for fibroblasts and a stimulatory factor for collagen synthesis.