Rat Dorsal Skin Research Articles

Behavior of the different implant materials in acute infection and efficacy of antibiotherapy: Experimental study in rats

In this study, we propose a comparison of the behaviors of four different implant materials in case of acute infection: expanded polytetrafluoroethylene (e-PTFE), porous high density polyethylene (PHDPE), silicone, and autogenous cartilage tissue. The efficacy of prophylactic and therapeutic antibiotic therapies was also investigated in a rat model as four groups: group A, acute infection and no antibiotic therapy (n = 24); group B, acute infection and prophylactic antibiotic therapy (n = 24); group C, acute infection and therapeutic antibiotic therapy (n = 24); and control, no infection and no antibiotic therapy (n = 24). All materials with dimensions of approximately 1 x 1 cm(2) diameter were implanted separately under the dorsal skin of rats. Staphylococcus aureus was used as the infectious agent and antibiotic therapy was done with seftriaxone (Desefin, I.M., 20 mg/kg/day). Tissue specimens were obtained on postoperative days 14 and 21. Semiquantitative and qualitative alterations existing in the connective tissue neighboring the implant material (reaction zone-capsule tissue), fixation to the host tissue, cellular ingrowth (interstice qualitatively), and infection signs were assessed either macroscopically or microscopically. In group A, all materials were affected negatively that led to continuous regression in the wound healing process. Fixation of the cartilage to the surrounding tissue was weak compared with other groups. Fibrovascular tissue ingrowth in porous implants was delayed, and no regular capsule formation was observed around silicone implants. In group B, outcomes were similar to control groups. Porous materials showed tissue ingrowth into the pores as good as the control group. Regular capsular tissue formed around the silicone implants and cartilage tissues. In group C, where silicone had been used, wound healing was not as good as in group B and the control group. In the e-PTFE group, the granulation tissue forming through the pores did not show a good quality as the control group, and capsule formation around the material was irregular, leading to insufficient fixation. While the wound healing properties of the PHDPE group were not as good as the control group, there was no difference in terms of fixation to the wound bed. On the other hand, wound healing of the cartilage group was as satisfying as the control group.

Activation and sensitization of C and Aδ afferent fibers mediated by P2X receptors in rat dorsal skin

The present study investigated the activation and sensitization effects of local injection of P2X receptor agonist α,β-methylene ATP (αβ-meATP) into the receptive fields of afferent fibers innervating dorsal hairy skin in anesthetized rats. Single unit activities of afferent fibers were recorded by means of isolation of the fiber filaments from the dorsal cutaneous nerve branch. A total of 237 fibers were obtained. Of these, 67 were classed as C fibers, 104 as Aδ fibers and 66 as Aβ fibers. When αβ-meATP (0.1–100 μM, 10 μl) was injected subcutaneously into the receptive fields of these units, C and Aδ fibers demonstrated a dose-related increase in the discharge rates of the response. The activated proportion of C and Aδ fibers with a response to the drug also increased with dose. However, Aβ fibers did not exhibit significant activation. Furthermore, injection of αβ-meATP (10 μl) at a concentration of 100 μM resulted in a significant decrease of mechanical thresholds in C and Aδ fibers compared with pre-injection baseline ( P < 0.05). In control experiments, injection of the vehicle phosphate-buffered saline (PBS, 10 μl) had no effect on all units tested. αβ-meATP (100 μM, 10 μl) followed by pyridoxal phosphate-6-azophenyl-2′,4′-disulfonic acid (PPADS), a P2X receptor antagonist, successfully blocked the activation and sensitization effects of αβ-meATP on C and Aδ fibers tested. These results suggest that peripheral P2X receptors are involved in mediating peripheral excitation of C and Aδ fibers.

Alterations in Gene Expression in Rat Skin Exposed to56Fe Ions and Dietary Vitamin A Acetate

The purpose of the present work was to examine gene expression patterns in rat skin exposed to a beam of (56)Fe ions, a surrogate for the high-energy, heavy-ion galactic radiation background, as a basis for obtaining a better understanding of the possible mechanism(s) behind the radioprotective activity of vitamin A. A 2 x 4-cm rectangle of dorsal rat skin was exposed to 1.01 GeV/nucleon (56)Fe ions generated by the Alternating Gradient Synchrotron at Brookhaven National Laboratory. Gene expression patterns were monitored in either the presence or absence of a 250-ppm dietary supplement of vitamin A acetate in powdered lab chow. Although vitamin A and other retinoids show anti-carcinogenic activity in several animal models, the underlying changes in gene expression have not been examined extensively. At either 1 or 7 day after irradiation, a 1-cm square of irradiated and control rat skin was excised and analyzed using the Affymetrix rat microarray (RG_U34A) system. Microarray responses were displayed and processed by GeneSpring 7.0 and GOTree software. At 1 day after 3 Gy of (56)Fe-ion irradiation, the expression of 110 genes was significantly up-regulated (P < = 0.05) in comparison to levels in control rat skin, while no genes were altered by the vitamin A acetate supplement alone. Combined with (56)Fe-ion radiation, the vitamin A acetate supplement blocked the expression of 88 (80%) of the 110 genes and eliminated 16 of 18 gene categories that were significantly altered (all increased) by the (56)Fe-ion radiation. Categories with large numbers of genes eliminated by the retinoid included response to stress, 33 genes; response to biotic stimulus, 38 genes; signal transduction, 35 genes; and regulation of cellular/physiological process, 40 genes. Even for immune response and response to biotic stimulus, the only two categories that remained significantly altered in the presence of the vitamin, the combined number of altered genes was reduced from 74 to 13. No significant alterations in gene expression were found at 7 days relative to the numbers in controls. The results indicate that at 1 day dietary vitamin A acetate strongly interfered with (56)Fe-ion-induced gene expression within the broad categories of stimulus- and stress-related genes, implying that the latter gene categories likely play a role in the radioprotective action of the vitamin.

Scallop shell extract promotes recovery from UV-B-induced damage in rat skin epidermal layer

It has been previously reported that scallop shell extract can protect keratinocyte cells against UV-B-induced damage in vitro by acting as an antioxidant and a growth promoter. To establish the growth promoting activity of scallop shell extract, the effect was investigated in vivo. Exposure of rat dorsal skin to UV-B caused the formation of erythema and eschar. Either the scallop shell extract or vehicle (water) was applied once a day for 5 days to the injured dorsal area and the area of the erythema and eschar was estimated using National Institute of Health (NIH) image software. Wound healing of the erythema and eschar was clearly promoted after application of scallop shell extract when compared to application of the vehicle control. Histological studies indicated that scallop shell extract promoted the recovery of the epidermal layer. These results suggest that scallop shell extract activates rat keratinocyte cells and promotes the turnover of skin stratum corneum. This conclusion was also supported by measurement of the turnover rate of the stratum corneum. Therefore, scallop shell extract may be effective in protecting skin against UV-B.

Basic Fibroblast Growth Factor (bFGF, FGF-2) Potentiates Leukocyte Recruitment to Inflammation by Enhancing Endothelial Adhesion Molecule Expression

Basic fibroblast growth factor (bFGF, FGF-2) is a potent angiogenic factor and endothelial cell mitogen. Although bFGF levels are increased in chronically inflamed tissue, its role in inflammation is unclear. We investigated the effect of bFGF on acute dermal inflammation and the recruitment of monocytes, T cells, and neutrophils. Leukocyte recruitment to inflamed sites was quantified with radiolabeled leukocytes. Intradermal injection of bFGF in rats did not induce leukocyte recruitment or inflammation. However, the recruitment of leukocytes to inflammation induced by tumor necrosis factor-alpha, interferon-gamma, C5a, or a delayed hypersensitivity reaction was enhanced by bFGF by 55 to 132% (P < 0.05). Either acute or prolonged bFGF treatment of dermal sites had this effect. The potentiating effect of bFGF on leukocyte recruitment was also seen in joints. There was no associated modulation of vascular permeability, blood flow, or angiogenesis in the sites by bFGF. However, the expression of the endothelial cell adhesion molecules (CAMs) for leukocytes, P-selectin, E-selectin, and ICAM-1, was significantly up-regulated in the inflamed tissue by bFGF, as quantified by radiolabeled anti-CAM antibody binding in vivo. Thus, although not directly proinflammatory, bFGF synergistically potentiates inflammatory mediator-induced leukocyte recruitment, at least in part, by enhancing CAM up-regulation on endothelium.

Melatonin effect on endothelial cells reduces vascular permeability increase induced by leukotriene B 4

The aim of this study was to investigate the effect of melatonin on the inflammatory increase in vascular permeability. Vascular permeability was stimulated by a nonspecific pro-inflammatory agent (carrageenan), by drugs that disrupt endothelial cells junction (histamine, serotonin or bradykinin) or drugs that promote neutrophil recruitment (leukotriene B 4 or N-formyl-methionyl-leucyl-phenylalanine fMLP). Vascular permeability was measured by Evan's blue dye extravasation after simultaneous injection of melatonin and the pro-inflammatory drugs in rat dorsal skin. Melatonin only reduced the increase in vascular permeability induced by leukotriene B 4, which activates both neutrophil and endothelial cells. The neutrophil expression of CD18 induced by leukotriene B 4 or fMLP was not changed by melatonin. On the other hand, melatonin inhibited the leukotriene B 4-induced endothelial cells hyperadhesiveness. Our findings suggest that vascular permeability reduction induced by local melatonin injection is mediated by a reduction of endothelial cells ability to interact with neutrophils.

Efficacy and mechanism of adenovirus-mediated VEGF-165 gene therapy for augmentation of skin flap viability

Skin ischemic necrosis due to vasospasm and/or insufficient vascularity is the most common complication in the distal portion of the skin flap in reconstructive surgery. This project was designed to test our hypothesis that preoperative subdermal injection of adenoviral vectors encoding genes for vascular endothelial growth factor-165 (Ad.VEGF-165) or endothelial nitric oxide (NO) synthase (Ad.eNOS) effectively augments skin viability in skin flap surgery and that the mechanism of Ad.VEGF-165 gene therapy involves an increase in synthesis/release of the angiogenic and vasodilator factor NO. PBS (0.5 ml) or PBS containing Ad.VEGF-165, Ad.eNOS, or adenovirus (Ad.Null) was injected subdermally into the distal half of a mapped rat dorsal skin flap (4 x 10 cm) 7 days preoperatively, and skin flap viability was assessed 7 days postoperatively. Local subdermal gene therapy with 2 x 10(7)-2 x 10(10) plaque-forming units of VEGF-165 increased skin flap viability compared with PBS- or Ad.Null-injected control (P < 0.05). Subdermal Ad.VEGF-165 and Ad.eNOS gene therapies were equally effective in increasing skin flap viability at 5 x 10(8) plaque-forming units. Subdermal Ad.VEGF-165 therapy was associated with upregulation of eNOS protein expression, Ca2+ -dependent NOS activity, synthesis/release of NO, and increase in capillary density and blood flow in the distal portion of the skin flap. Injection of the NOS inhibitor Nomega-nitro-L-arginine (15 mg/kg im), but not the cyclooxygenase inhibitor indomethacin (5 mg/kg im), 45 min preoperatively completely abolished the increase in skin flap blood flow and viability induced by Ad.VEGF-165 injected subdermally into the mapped skin flap 7 days preoperatively. We have demonstrated for the first time that 1) Ad.VEGF-165 and Ad.eNOS mapped skin flap injected subdermally into the mapped skin flap 7 days preoperatively are equally effective in augmenting viability in the rat dorsal skin flap compared with control, 2) the mechanism of subdermal Ad.VEGF-165 gene therapy in augmenting skin flap viability involves an increase in NO synthesis/release downstream of upregulation of eNOS protein expression and Ca2+ -dependent NOS activity, and 3) the vasodilating effect of NO may predominantly mediate subdermal Ad.VEGF gene therapy in augmenting skin flap blood flow and viability.

T-2 Toxin and Apoptosis

T-2 toxin is a cytotoxic fungal secondary metabolite produced by various species of Fusarium. This paper reviews the reported data about the development and/or mechanisms of T-2 toxin-induced apoptosis in the hematopoietic, lymphoid and gastrointestinal tissues, dorsal skin and fetal tissues of mice and rats. Apoptosis occurs earlier in hematopoietic tissues than in lymphoid tissues, and moreover there is a difference among lymphocyte populations in the susceptibility to T-2 toxin. C-fos plays an important role in the early phase of T-2 toxin-induced apoptosis in hematopoietic and lymphoid tissues through mobilization of [Ca2+]i and the PKC-dependent pathway, but not through Fas/Fasligand or p53-related pathways. In the gastrointestinal tract, apoptosis develops earlier in the small intestine than in the stomach, and is more prominent in the small intestine than in the large intestine. In the dorsal skin topically treated with T-2 toxin, epidermal basal cell proliferating activity is first suppressed due to the elevated TGF-β1 expression, and then basal cell apoptosis develops concomitantly with the elevation of c-fos, c-jun and TNF- α mRNAs expression. In the fetuses, T-2 toxin-induced apoptosis is mainly observed in the central nervous and skeletal systems. In the fetal brain, T-2 toxin induces oxidative stress, followed by activation of the MAPK-JNK-c-Jun pathway, finally resulting in apoptosis. The TNF receptor pathway may also be involved in T-2 toxin-induced apoptosis in the fetal brain. Thus, the development and mechanisms of T-2 toxin-induced apoptosis differ somewhat depending on the tissues affected.

Doxepin by Topical Application and Intrathecal Route in Rats

The tricyclic antidepressant, doxepin, has been reported to be a potent local anesthetic in rat sciatic nerve blockade. We hypothesized that topical doxepin has significantly longer antinociception compared with control and intrathecally compared with bupivacaine. Solutions of 0.3 mL of doxepin at 50, 75, and 100 mM and control (only the vehicle solution) were applied as a patch to the shaved dorsal skin of rats. After a 2-h contact interval, the patch was removed, and the rats were tested by three sets of six pinpricks. Inhibition of withdrawal to pain and cutaneous trunci muscle reflex were graded. In the second investigation, 60 muL of doxepin at 10, 20, and 50 mM was injected through intrathecal catheters implanted in the lumbar region of rats, which were evaluated for motor function, proprioception, and nociception. Topical doxepin at concentrations of 75 mM and 100 mM was significantly more effective than control (P < 0.05). Complete recovery for the 100-mM concentration occurred at 60 h, although two of five rats demonstrated erythema and scarring. Intrathecally, 20 mM of doxepin was not significantly different for motor and proprioceptive function from 23 mM (0.75%) bupivacaine; however, neurotoxicity (defined as persistent neurological deficit) commenced at 50 mM.

Localization of Myosin and Actin in the Pelage and Whisker Hair Follicles of Rat

The combined effects of myosin II and actin enable muscle and nonmuscle cells to generate forces required for muscle contraction, cell division, cell migration, cellular morphological changes, the maintenance of cellular tension and polarity, and so on. However, except for the case of muscle contraction, the details are poorly understood. We focus on nonmuscle myosin and actin in the formation and maintenance of hair and skin, which include highly active processes in mammalian life with respect to the cellular proliferation, differentiation, and movement. The localization of nonmuscle myosin II and actin in neonatal rat dorsal skin, mystacial pad, hair follicles, and vibrissal follicles was studied by immunohistochemical technique to provide the basis for the elucidation of the roles of these proteins. Specificities of the antibodies were verified by using samples from the relevant tissues and subjecting them to immunoblotting test prior to morphological analyses. The myosin and actin were abundant and colocalized in the spinous and granular layers but scarce in the basal layer of the dorsal and mystacial epidermis. In hair and vibrissal follicles, nonmuscle myosin and actin were colocalized in the outer root sheath and some hair matrix cells adjoining dermal papillae. In contrast, most areas of the inner root sheath and hair matrix appeared to comprise very small amounts of myosin and actin. Hair shaft may comprise significant myosin during the course of its keratinization. These results suggest that the actin-myosin system plays a part in cell movement, differentiation, protection and other key functions of skin and hair cells.

Photoacoustic Diagnosis of Burns in Rats

Accurate burn depth assessment is important for determining the appropriate treatment plan for severe burn patients. However, conventional methods of diagnoses, such as visual observation and pinprick test, are often inaccurate. We previously proposed a new method for burn diagnosis in which photoacoustic signals originating from the blood in healthy tissue under the injured tissue are measured. In this study, we investigated the validity of this method by an experiment using rat scald burn models. Superficial dermal burns (SDBs), deep dermal burns (DDBs), and deep burns (DBs) were made in the dorsal skin of rats by using a Walker-Mason template. Wounds were irradiated with low-energy, 550-nm, nanosecond pulsed light, and photoacoustic signals induced were measured with a piezoelectric film as a function of postburn time. Measurement in normal skin as a control was also performed. Temporal profiles of the photoacoustic signals were converted into depth profiles using sound velocity of tissue, and for each profile, a peak showing highest signal intensity was selected. For this peak, the depth at which the signal rose (signal rise depth) and the depth that gave a peak value (signal peak depth) were recorded. Statistical analysis was performed to clarify the difference in depth information of signals between burn groups. Depth profiles of photoacoustic signals showed unique features depending on the degree of burn; pronounced peaks shifted to deeper tissue as the burn severity increased. This indicates that the zone of stasis formed due to injuries can be monitored. There were significant differences in both the signal rise depth and the peak depth between the control and SDB groups, SDB and DDB groups, and DDB and DB groups (p < 0.001). SDBs, DDBs, and DBs can be differentiated by photoacoustic signals, suggesting that the method proposed is useful for diagnosing burn injuries.

Enhancement of ultraviolet-induced apoptosis by NF-kappaB decoy oligonucleotides

A decoy strategy utilizing oligonucleotides (ODN) containing the specific binding sequence of a certain transcription factor has been developed and is considered to be a potential new class of antigene therapy. However, the application of this new therapeutic modality to skin diseases has not been fully documented. The aim of this work was to examine the effects of the nuclear factor (NF)-kappaB decoy ODN on UV-elicited skin change. Mouse keratinocyte Pam 212 cells were transfected with NF-kappaB decoy ODN to examine the effects of the decoy ODN on ultraviolet (UV) B-induced apoptosis. Tape-stripped rat dorsal skin was treated with an ointment containing NF-kappaB decoy ODN for the examination of the in vivo impact of the decoy ODN on sunburned cell (SBC) formation and UVB erythema. NF-kappaB decoy ODN specifically induced apoptosis of Pam 212 cells and SBC formation was significantly enhanced by topical NF-kappaB decoy ODN ointment, while UV-induced erythema was not affected. These data suggest that enhancement of UV-induced apoptosis by NF-kappaB decoy ODN may play a cancer-preventive role by further eliminating photodamaged keratinocytes.

Effect of Cog Threads under Rat Skin

The aging face loses the tensile strength of structural integrity. Cog threads have been used recently to tighten lax skin and soft tissue. A comparative study of the effects of cog, monofilament, and multifilament threads under rat skin. Each cog, monofilament, and multifilament thread was inserted under the facial skin of a cadaver and the panniculus carnosus of rat dorsal skin. The maximum holding strength (MHS) of the thread and the tearing strength of the skin around the thread were measured with a tensiometer. The thickness of the capsule around the thread and the myofibroblasts was observed histologically. In the cadaver, the MHS of the cog thread was 190.7 +/- 65.6 g. It was greater than that of the monofilament (22.4 +/- 7.7 g) or multifilament (40.4 +/- 19.7 g) thread. In the rat, the MHS of the cog thread was 95.1 +/- 18.8 g. It was greater than that of the monofilament (4.3 +/- 1.3 g) or multifilament (10.9 +/- 2.1 g) thread in the second week. The thickness of the capsule around the cog thread was 93.0 +/- 3.2 microm. It was thicker than the monofilament thread's capsule, 39.2 +/- 12.1 microm, in the fourth week. The number of myofibroblasts presented significantly more in the cog (96.0 +/- 72.4) than in the monofilament thread (4.3 +/- 4.4). The rumpled in-between skin suspended by each of the three different threads returned to its original state in 2 weeks. The cog thread placed under the rat skin immediately pulled the skin and subcutaneous tissue. The myofibroblasts around the thread played a role in fibrous tissue contracture 4 weeks postinsertion of the thread. These findings could be the basis for clinical application.

Expression pattern and intensity of protoporphyrin IX induced by liposomal 5-aminolevulinic acid in rat pilosebaceous unit throughout hair cycle

We have developed liposomal formulation of 5-aminolevulinic acid (ALA) to enhance topical delivery and examined ALA-induced protoporpyrin (PpIX) expression in rat pilosebaceous unit throughout hair cycle. Two types of liposomes--glycerol dilaulate (GDL) and phosphatidylcholine (PC)--were formulated and both liposomal ALA increased PpIX expression in rat dorsal skin and pilosebaceous units when compared with free ALA. However, iontophoresis combined with liposomal ALA reduced the expression intensity of PpIX in hair bulbs although it achieved deeper and wider expression of PpIX through transfollicular pathway. After topical application in intact or depilated rat skin, liposomal ALA produced excellent PpIX expression in pilosebaceous units. The expression pattern and intensity of PpIX changed in hair cycle-dependent manner: specific expression only in sebaceous glands was observed at telogen; strong expression in whole pilosebaceous units was shown at anagen with intense expressions in hair bulbs and sebaceous glands; and a pattern similar to anagen but reduced intensity in the hair bulbs was seen at catagen. Throughout hair cycle, the expression pattern and intensity were dramatically changed in hair follicular epithelial cells depending on the cell density and proliferation activity of those cells, whereas those were consistent in sebaceous glands regardless of hair cycle. Little expression was shown in dermis. Photoactivation effect of 20% liposomal ALA-PDT using a red filtered-halogen lamp damaged sebaceous glands, hair follicles and epidermal layers. Formation of a thicker epidermal layer was observed, and hair induction after depilation was inhibited along with damage in sebaceous glands.

Local application of morphine suppresses glutamate-evoked activities of C and Aδ afferent fibers in rat hairy skin

Behavior studies have demonstrated that local application of morphine in peripheral tissues resulted in a significant antinociceptive effect, but there has been no electrophysiological evidence to support the peripheral mechanism of opioid antinociception. The purpose of the present study was to investigate whether local application of morphine suppressed the glutamate-evoked activities of C and Aδ primary afferent fibers in dorsal hairy skin of rat in vivo. The single unit activities of the C and Aδ afferent fibers were recorded by means of isolation of the fiber filaments from the dorsal cutaneous nerve branches, and the effects of glutamate and glutamate plus morphine injected into the receptive field on these activities were determined. The results revealed that most of the C and Aδ fibers were excited significantly by local injection of glutamate (0.3 mM), with the percentage being 81% (22/27, for C fibers) and 73% (36/49, for Aδ fibers), respectively. The glutamate-induced excitatory response was significantly suppressed by co-injection of morphine (1.0 mM). The mean discharge rates of C fibers and Aδ fibers decreased from 28.96 ± 6.85, 28.99 ± 3.79 impulses/min to 4.40 ± 1.76, 2.72 ± 0.71 impulses/min, respectively. The suppressing effect of morphine was reversed by pretreatment with opioid receptor antagonist naloxone (1.0 mM). These findings suggest that local application of morphine can suppress the glutamate-evoked activities of the fine fibers in rat hairy skin and thus provide an electrophysiological evidence for peripheral antinociception of opioids.

Nonsurgical Delay of Dorsal Rat Cutaneous Flap Using a Long-Pulsed 1064-nm Nd:YAG Laser with a Contact Cooling Device

This study evaluated the efficiency of a long-pulsed neodymium:yttrium-aluminum-garnet laser, operating at 1064 nm and equipped with a contact cooling device, in the delay of a caudally based dorsal rat skin flap (10 x 3 cm). This laser has deeper tissue penetration and has not been used for this purpose before. Twelve male Sprague-Dawley rats were used in each of six groups. The delay effects of three different laser treatment patterns (only longitudinal borders, cephalic and longitudinal borders, and entire surface of the 10 x 3-cm flap) were compared with an acute untreated control flap as well as two surgical delay methods (incision of longitudinal borders and incision of longitudinal borders plus flap undermining). The laser effects on the cutaneous vasculature and perfusion were assessed by intravenous fluorescein injection, histologic study, microangiography, and in vivo real-time video monitoring. Selective thermocoagulation of subdermal vessels was achieved using a 6-mm spot, 140-J/cm fluence, and 40-msec pulse width. In the cephalic and longitudinal borders laser-treated group, a delay effect was achieved. The maximum delay effect was achieved by the surgical delay group that used the method of incision of the longitudinal borders plus flap undermining. Laser treatment of only the longitudinal borders did not improve flap survival, whereas treatment of the entire flap surface significantly reduced flap survival. Nonsurgical delay of a dorsal rat cutaneous flap is possible by selective occlusion of the subdermal plexus at the longitudinal and cephalic borders of the planned flap using a long-pulsed 1064-nm neodymium:yttrium-aluminum-garnet laser equipped with a contact cooling device.

Effect of Viscous Injectable Pure Alginate Sol on Cultured Fibroblasts

Alginates have a wide variety of potential clinical applications, including use in cell encapsulation, drug delivery, and tissue engineering. Although the compounds are typically used in the form of a calcium hydrogel, alginates in this form possess several disadvantages, including low biodegradability, induction of foreign body reactions, and cytotoxicity secondary to Ca2+ efflux and contamination with bioincompatible substances. Thus, the goal of the present study was to develop a new method of obtaining sterilized, pure, highly viscous alginate sol from seaweed alginates and to determine its utility as an injectable antiadhesion drug. Viscous injectable pure alginate sol was produced from a commercially available sodium alginate, and its molecular and physical characteristics were analyzed. The biological properties of the viscous injectable pure alginate sol were analyzed using cultured fibroblasts prepared from the dorsal skin of neonatal rats to determine its biocompatibility and its effects on cell proliferation, cell migration, and collagen lattice contraction. The mannuronic acid-to-glucuronic acid ratio of viscous injectable pure alginate sol, as determined by nuclear magnetic resonance studies, was 1.2, and its viscosity at 5 percent was 17,800 mPa. Purification used to produce viscous injectable pure alginate sol decreased contamination by insoluble particles by 20 percent and decreased polyphenol concentration by 17 percent. In vitro analyses with cultured fibroblasts demonstrated that viscous injectable pure alginate sol had excellent biodegradability and biocompatibility and that viscous injectable pure alginate sol inhibited fibroblast proliferation and migration. Furthermore, assessment of collagen contraction with floating fibroblast-loaded collagen lattices indicated that viscous injectable pure alginate sol enhanced wound healing in surrounding connective tissues. The authors conclude that viscous injectable pure alginate sol can inhibit scar formation by presenting a physical barrier to invading fibroblasts and by enhancing wound healing of surrounding tissues.

생체내 예측 및 흰쥐를 이용한 니코틴 패취의 약물동력학적 평가

Nicotine transdermal therapeutic systems have been regarded as an effective mean to aid smoking cessation. However, most of nicotine in the market have some problems such as unpleasant side effects and skin irritation due to the excess amount of the drug permeated and the properties of the additives employed. In order to solve these problems, new nicotine were formulated using biocompatible additives. The optimized formula of the drug layer consisted of nicotine, propylene glycol and poloxamer 188 at the ratio of 1.2: 17.0: 2.0. The drug layer had the sickness of , the pH of 8.12. The skin permeation rate of nicotine from optimized nicotine patch (NP) was . Transdermal administration of nicotine patch has been carried out for the determination of pharmacokinetic parameters in rats. Steady-state plasma concentration of nicotine following transdermal application of NP (area of patch = ) on the dorsal skin of rats was 143.2 ng/ml and AUC for 24 hrs was 3,022 ng h/ml. In case of and Nicotinell , the steady-state plasma concentration of nicotine and ACU for 24 hrs were 428.9 ng/ml, and 155.3 ng/ml, , respectively. NP showed the experimental plasma nicotine concentration profile was very similar to the simulated one and had an appropriate skin permeation rate and a steady-state concentration of nicotine, which can show therapeutic blood levels of the drug for 24 hrs without severe side effects.

Evaluation of Flashlamp-Pumped Pulsed-Dye Laser (585 nm) in Nonsurgical Delay of Dorsal Rat Cutaneous Flaps

This study evaluated the efficiency of a flashlamp-pumped pulsed-dye laser operating at 585 nm in the delay of a caudally based, 10 x 3-cm dorsal rat skin flap. Two different laser treatment patterns (only longitudinal borders and the entire surface of the proposed flap) for two different fluences (6 J/cm and 8 J/cm) were compared with an acute untreated control flap as well as two surgical delay methods (incision of longitudinal borders and incision of longitudinal borders plus flap undermining). Twelve male Sprague-Dawley rats were used in each of seven groups. Two additional rats were used for histologic evaluation and two rats were used for in vivo real-time video monitoring studies. Two weeks after delay procedures, the flaps were raised and sutured on the primarily closed flap donor area. After 5 days, the length of flap survival was measured. The effects of the laser on the cutaneous vasculature and perfusion were assessed by intravenous fluorescein injection, histologic analysis, microangiography, and in vivo real-time video monitoring. No statistically significant improvement in flap survival was observed in any of the laser treatment groups. The overall findings indicate that the flashlamp-pumped pulsed-dye laser operating at 585 nm did not penetrate deep into skin and coagulate the subdermal plexus with tested laser settings and did not induce the delay phenomenon.

Gene transfer of bFGF to recipient bed improves survival of ischemic skin flap

The recipient bed is a promising target of angiogenic therapy to treat ischemic skin flaps. We delivered basic fibroblast growth factor (bFGF) gene to the recipient bed by a plasmid-based method with electroporation, and assessed the effects on flap viability in a rat dorsal skin flap model. A 25 x 90 mm(2) axial skin flap was elevated on the back of male Sprague-Dawley rats. Two days before flap elevation, an expression plasmid vector containing the bFGF gene with the signal sequence was injected into the dorsal muscles beneath the skin flap, and then electroporation was delivered (FGF-E(+) group). As control, rats were injected with a plasmid vector containing LacZ gene (LacZ-E(+) group), instead of bFGF gene. Other groups of animals received plasmid vector containing bFGF (FGF-E(-) group) or LacZ (LacZ-E(-) group) gene without electroporation. Seven days later, the area of necrosis and neovascularisation of the skin flap were evaluated. The bFGF gene was successfully transferred to the dorsal muscles, and bFGF was expressed in muscle tissue. The area of flap necrosis (%) in the FGF-E(+) group (21.7+/-5.3%) was significantly smaller than that in the LacZ-E(+) (28.3+/-4.1%), FGF-E(-) (29.7+/-3.3%), and LacZ-E(-) (28.1+/-2.5%) groups. Postmortem angiograms and histological analyses showed that vascularisation in the distal part of the skin flap was significantly increased in the FGF-E(+) group compared with the other groups. These findings suggested that gene delivery of bFGF to the recipient bed muscles enhanced vascularity and viability of an ischemic skin flap, and that plasmid-based gene delivery with electroporation was a suitable delivery method.