Hairless Rat Research Articles

Fecundity difference is related to the production of reproductive pheromones in rats.

In rodents, male-derived pheromones play fundamental roles in reproduction. The Hirosaki hairless rat (HHR) is a mutant strain derived from the Sprague-Dawley rat (SDR). While investigating the natural mating between single males and females, (SDR♂ x SDR♀) or (HHR♂ x HHR♀), the HHRs showed higher fecundity than the SDRs; the mean period between mating and delivery was shorter and every HHR pair gave birth, whereas approximately half of the SDR pairs gave birth in the 3 months of experimental testing. By changing partners between the HHRs and SDRs, (SDR♂ x HHR♀) or (HHR♂ x SDR♀), we attributed the fecundity difference to males. However, no significant difference was observed in the litter size, the concentration, morphology, or motility of sperm in the cauda epididymis, or the testosterone concentration in the serum between the SDR and HHR males. When an SDR and HHR male were simultaneously mated with a single female, the HHR males always succeeded in leaving progeny. Therefore, we assumed that the reason for the fecundity difference was the difference in copulation efficiency and focused on male-derived pheromones that may induce reproductive behaviors in females. Whereas Darcin (MUP20), one of the pheromones produced in the liver, did not appear to be involved, the extraorbital lacrimal gland (ELG) was heavier in the HHR males and showed larger amounts of pheromones, namely exocrine gland-secreting peptide 1 (ESP1) and cystatin-related protein 1 (CRP1). These results suggest that the fecundity difference is due to the difference in amounts of ELG-derived pheromones.

Fluctuations in Detection Indicators and Their Significance for the Diagnosis of Early Pressure Injury in Rat Models.

The aim of this study was to identify the most meaningful diagnostic indicator for distinguishing blanchable erythema (BE) and stage 1 pressure injury (early PI) in an in vivo (rat) model. A prospective case-control design was used to complete a horizontal and vertical comparison of detection indicators during the process of fading of BE or the deterioration of early PI into ulcer in rat models. The sample comprised 5 hairless rats with 20 injuries, of which 10 were BE and the other 10 were early PI. Data were collected at Nagano College of Nursing in 2020 in Nagano, Japan. The BE and PI rat models were established by subjecting the dorsal skin of a hairless rat to compression between 2 neodymium magnets for 45 minutes and 3.45 hours, respectively. The affected skin was observed based on the following: (1) photography, (2) hardness, (3) temperature, (4) moisture, and (5) spectrophotometric (a* value and ultraviolet [UV] reflectance) measurements. All measurements of BE were performed at the beginning to 60 minutes after decompression, and those for early PI were performed until 48 hours after decompression. Multiple BE factors, such as the degree of erythema (macroscopy and a* value), hardness, temperature, and moisture, were found to have unstable fluctuations. Only UV reflectance gradually decreased from 6 hours and decreased significantly at 48 hours after decompression (P = .001 vs 1 hour). In contrast to early PI, erythema in BE obviously faded within 10 minutes. Study findings indicate that a continuous decrease in UV reflectance can reflect the worsening of hemorrhage in early (stage 1) PI. In contrast, other indicators including photography, skin hardness, temperature, and moisture fluctuated and did not prove predictive for PI progression. The obvious fading of erythema in BE a short time after decompression can be used for clinical observations.

Comparative evaluation of efficiency of burn wound healing with derma-based hydrogel: a preclinical experimental study

Background. Burn wound healing is recognized as a complex process involving synergetic interactions between different cells, cytokines and growth factors. The adverse interactions can underlie chronicization of the process. Accordingly, the paper presents a relevant study into mechanisms of natural wound dressings, capable of influencing the processes of inflammation, angiogenesis, and skin resurfacing.Objective. To carry out a comparative evaluation of efficiency of burn wound healing with derma-based hydrogel according to the dynamics of proand anti-inflammatory factors.Methods. Development of a hydrogel material involved dermis samples of Landrace breed of pig, subjected to partial alkaline hydrolysis. In order to carry out a comparative evaluation of burn wound healing efficiency, the authors simulated direct thermal injury in three groups of sphinx (hairless) rats: group 1 (control group) — rats without treatment (n = 20), group 2 (comparison group) — rats treated with Levomekol ointment (n = 20), and group 3 (experimental group) — rats treated with hydrogel material (n = 20). Before and after injuring on days 1, 3, 7, 14, the content of cytokines interleukin-1β, interleukin-4, interleukin-6, interleukin-8, interleukin-10, tumor necrosis factor-α by enzyme immunoassay. The wound samples were explanted for histological examination on days 3, 7 and 14 after the beginning of the experiment. Statistical processing of the obtained results on DNA content in hydrogel, cytokine content in serum and morphometric data was performed using GraphPadPrism 6.04, Microsoft Excel 2016 (Microsoft, USA).Results. When determining the content dynamics of nonspecific markers of inflammation, an increase in the concentrations of interleukin-1β and tumor necrosis factor-α on day 1 after the hydrogel application was recorded, as well as an increase in interleukin-6 on days 3 and 7, while the concentrations of interleukin-8 did not change significantly throughout the experiment. Thus, dermal components are indicated to participate in the inhibition of acute-phase immune reactions. With regard to anti-inflammatory factors, the study revealed a decrease in the concentration of interleukin-10 on days 1 and 7, an increase in interleukin-4 on day 3 as compared to the control group, thereby indicating a pronounced anti-inflammatory effect and prolonged action of the hydrogel.Conclusion. Comparative analysis of the pro-inflammatory cytokines levels (interleukin-1β, interleukin-8) showed pronounced anti-inflammatory effects of the derma-based hydrogel material. Introduction of exogenous biological components of the extracellular matrix (collagen and its hydrolysates) had a significant influence on the regulation of anti-inflammatory cytokines synthesis, presumably contributing to faster successful epithelization and wound healing.

A comprehensive analysis of multi-circulatory disorders in early pressure injury and their diagnostic significance in rat models

Early pressure injury (PI) progression is associated with multi-circulatory disorders and they interplay with each other, resulting in a lack of a satisfactory diagnostic method. We generated early PI and blanchable erythema hairless rat models. Transparent disc method and capillary refilling time test (CRTT) results were recorded with ultraviolet camera to capture the dynamics changes, and the blanching index and refilling index were set for comprehensive analysis. The deteriorated areas of early PI showed non-blanchable erythema (NBE) and an increase in erythema at 0.5 and 6 h with the transparent disc method. CRTT showed a marked refilling delay at 12 h. The comprehensive analysis of blanching index and refilling index showed a significant change in erythema from NBE at 0.5 h and ischemia progressing to hemorrhage at 18 h. There was also a marked difference in the deteriorating and improving areas within the same erythema. Pathological analysis showed inflammatory cell infiltration, with marked edema accompanied by increased hemorrhage and tissue necrosis. Furthermore, small arteries and veins with thrombosis and microthrombi were observed. Consistent ischemia after decompression and subsequent hemorrhage are important indicators, and comprehensive analysis can help increase the positive diagnosis rate over that for other circulatory disorders alone.

A nude mutant rat derived from Sprague Dawley-National Institute of Nutrition rat colony with normal thymus: A potential model for noncommunicable diseases.

A spontaneous mutant rat with a hairless phenotype and an intact thymus was discovered in a long-standing Sprague Dawley-National Institute of Nutrition (SD/NIN) rat colony at a national animal resource facility. We conducted extensive phenotypic and biochemical analyses on this mutant strain to determine its suitability as a preclinical model for immunocompetent testing in noncommunicable disease research. We subjected the mutant rats to strict and frequent phenotypic and genetic surveillance to accomplish this objective. The animals were assessed for food intake, body weight, blood cell profile, clinical chemistry, adipose tissue deposition, and bone mineral density (BMD) using total electrical body conductance (TOBEC) and dual-energy X-ray absorptiometry (DXA) analysis. Initially, only two hairless mutant rats, a male and a female, were born from a single dam in the SD/NIN rat strain. However, the results indicate that the mutant colony propagated from these unique pups displayed distinct phenotypic features and exhibited differences in feeding behavior, weight gain, and clinical biochemistry. The food conversion rate was significantly higher in nude females (2.8-fold) while 26% lower in nude males. Both sexes of nude rats had significantly higher triglycerides and lower glucose levels in females. However, glucose levels did not change in male nude rats. Furthermore, nude female and male rats had significantly lower fat (TOBEC) and bone mineral content (DXA). Nonetheless, BMD was only slightly lower (7%-8%) compared to the heterozygous groups. These findings indicate that the spontaneous mutant rat has the potential to serve as an immunopotent and modulatory testing system in pharmacokinetics/pharmacodynamics and toxicology, which can be further explored for therapeutic drug discovery.

Thermal preconditioning can reduce the incidence of intraoperatively acquired pressure injuries

Intraoperatively acquired pressure injuries (IAPIs) occur frequently among patients who undergo surgical procedures that last longer than 3 h. Several studies indicated that heat shock proteins (HSPs) play an important role in the protection of stress-induced damages in skin tissues. Hence, the aim of this study was to investigate the potential preventive effect of thermal preconditioning (TPC) on IAPIs in surgical patients and rats and to identify the differentially expressed HSP genes in response to the above treatment. TPC was performed on one group of hairless rats before the model of pressure injuries was established. Subsequently, the size of skin lesions was measured and the expression levels of mRNA and protein of HSPs of the pressured skin were detected by real-time polymerase chain reaction (RT-PCR), western blot, and immunohistochemical staining. For human studies, 118 surgical patients were randomly divided into the TPC group (n = 59) and the control group (n = 59), respectively. The temperature and pressure of sacral skin, as well as the incidence of pressure injury (PI) were detected and compared. In animal studies, TPC significantly reduced both the size and incidence of PI in rats on the second, third and fourth days post treatment. In addition, the expression levels of both mRNA and protein of HSP27 were increased in the TPC group, compared with the control group. Immunohistochemical staining showed that HSP27 was distributed in various types of dermal cells and increased in basal cells. In human studies, a significant reduction (75%) of IAPIs was observed among the patients in the TPC group. TPC can reduce the incidence of PI in rats and humans, and the upregulation of HSP27 may play an important role in this biological progress. Further studies are warranted to explore the molecular mechanism of the preventive effect in PI mediated by HSP27.

Semi-Solid Dosage Forms Containing Pranoprofen-Loaded NLC as Topical Therapy for Local Inflammation: In Vitro, Ex Vivo and In Vivo Evaluation.

Pranoprofen (PRA)-loaded nanostructured lipid carriers (NLC) have been dispersed into blank gels composed of 1% of Carbomer 940 (PRA-NLC-Car) and 3% of Sepigel® 305 (PRA-NLC-Sep) as a novel strategy to refine the biopharmaceutical profile of PRA, for dermal administration in the treatment of skin inflammation that may be caused by possible skin abrasion. This stratagem intends to improve the joining of PRA with the skin, improving its retention and anti-inflammatory effect. Gels were evaluated for various parameters such as pH, morphology, rheology, and swelling. In vitro drug release research and ex vivo permeation through the skin were carried out on Franz diffusion cells. Additionally, in vivo assays were carried out to evaluate the anti-inflammatory effect, and tolerance studies were performed in humans by evaluating the biomechanical properties. Results showed a rheological profile common of semi-solid pharmaceutical forms for dermal application, with sustained release up to 24 h. In vivo studies using PRA-NLC-Car and PRA-NLC-Sep in Mus musculus mice and hairless rats histologically demonstrated their efficacy in an inflammatory animal model study. No signs of skin irritation or modifications of the skin's biophysical properties were identified and the gels were well tolerated. The results obtained from this investigation concluded that the developed semi-solid formulations represent a fitting drug delivery carrier for PRA's transdermal delivery, enhancing its dermal retention and suggesting that they can be utilized as an interesting and effective topical treatment for local skin inflammation caused by a possible abrasion.

Rapid Manufacturing Approach of an Ultrathin Moisture Sensor for Health Monitoring.

This study developed a rapid manufacturing approach for a moisture sensor based on contactless jet printing technology. A compact measurement system with ultrathin and flexure sensor electrodes was fabricated. The proposed sensor system focuses on continuous urine measurement, which can provide timely information on subjects to ensure efficient diagnosis and treatment. The obtained results verify that the proposed sensor system can exhibit a typical responsivity of up to -7.76 mV/%RH in the high-sensitivity range of 50-80 %RH. A preliminary field experiment was conducted on a hairless rat, and the effectiveness of the proposed ultrathin moisture sensor was verified. This ultrathin sensor electrode can be fabricated in the micrometer range, and its application does not affect the comfort of the user. The ultrathin electrode sensors can be printed directly on the diaper or undergarment of the user for in situ urine health monitoring, particularly of infants and the elderly.

Fluorapatite-Coated Percutaneous Devices Promote Wound Healing and Limit Epithelial Downgrowth at the Skin-Device Interface

A percutaneous osseointegrated device becomes deeply ingrown by endosteal bone and traverses the overlying soft tissues of the residual limb, providing a direct link to the bone-anchored artificial limb. Continuous wound healing around these devices can result in the formation of sinus tracts as “down-growing” epithelial cells are unable to recognize and adhere to the “nonbiological” implant surface. Such sinus tracts provide paths for bacterial colonization and deep infection. In order to limit adverse outcomes and provide a robust seal, it was hypothesized that by coating the titanium surface of the percutaneous post with the mineral component of dental enamel, down-growing epidermal cells might recognize the coating as “biological” and adhere to this nonliving surface. To test this hypothesis, sintered partially and fully fluoridated hydroxyapatite (HA) was chosen as coatings. Using an established surgical protocol, fluorapatite (FA), hydroxyfluorapatite (FHA), HA-coated percutaneous posts, and titanium controls were surgically placed under the dorsal skin in 20 CD hairless rats. The animals were sacrificed at four weeks, and implants and surrounding tissues were harvested and subjected to further analyses. Downgrowth and granulation tissue area data showed statistically significant reductions around the FA-coated devices. Moreover, compared to the control group, the FA- and HA-coated groups showed downregulation of mRNA for EGFr, EGF, and FGF-10. Interestingly, the FA-coated group had upregulation of TGF-α. These data suggest that FA could become an ideal coating material for preventing downgrowth, assuming the long-term stability of these coated surfaces can be verified in a clinically relevant animal model.

Avocado ( Persea americana Mill.) Seed Extract Cream 10% Inhibited The Increase MMP-12 Enzyme Levels And Elastosis In UVA Exposed Hairless Male Wistar Rats Skin

Background: Skin is the main target of environmental influences, especially chronic exposure to the suns UVA rays which will result in wrinkling, decreased skin elasticity, the appearance of loose skin, and a rough clinical appearance. In the dermal tissue, not only affects collagen fibers but also degradation of elastin fibers occurs through an increase in the MMP-12 enzyme levels called photoaging and is characterized by the accumulation of dystrophic elastin fibers throughout the dermal tissue in a process called Elastosis. Avocado seed (Persea americana Mill.) is a part of the fruit that contains high concentrations of flavonoids, phenols, and tannins, it has the potential as a powerful antioxidant. The aim of the present study is to evaluate the effectiveness of avocado (Persea americana Mill.) seed extract cream 10% inhibiting the increase in MMP-12 enzyme levels and elastosis in hairless male Wistar rats (Rattus norvegicus) which were exposed to ultraviolet A rays. Methods: A Randomized post-test-only control group design was conducted among 30 male Wistar rats for 10 consecutive days. They were divided into 3 groups as follows: group (K) as the negative control without any intervention, group (P1) with UVA rays exposure, and group (P2) with application of avocado (Persea americana Mill.) seed extraxt cream 10% and UVA rays exposure. The UVA dosage used is 5J/cm2 twice a day among P1 and P2 groups. Avocado (Persea americana Mill.) seed extract 10% was applied to the hairless Wistar rats 4 hours after the exposure of UVA rays. MMP-12 was calculated with Rat MMP-12 ELISA Test. Elastin fiber density was calculated by Imageraster software. Statistical analysis was carried out using SPSS version 25 in measure means, normality test, homogeneity test, and comparative test. Results: The results showed that the average MMP-12 enzyme level in the 10% avocado seed cream (P2) group 18.138 ± 0.168% was significantly different from the (K) group 1.073 ± 0.1553% as the negative control and the (P1) group 33.454 ± 1.068%. The mean density of elastin fiber in the cream of avocado seed extract group (P2) 12.42 ± 3.672% was significantly different from the group (K) 20.08 ± 4.994% and group (P1) 26.30 ± 6.822%. Comparative analysis using the Kruskal Wallis test for MMP-12 and the One Way Annova test for elastin fibers showed a p-value of < 0.05, thus indicating a significant difference between groups after treatment. The Least Significance Difference (LSD) test showed that there was a significant difference between the cream of avocado seed extract (P2) group and the other groups (p<0.05). Conclusions: The administration of avocado seeds (Persea americana Mill.) extract cream 10% effectively inhibits the increase in MMP-12 enzyme levels and elastosis in hairless male Wistar rat skin which was exposed to ultraviolet A irradiation.

Effect of ultrasound treatment of the skin on activation of Langerhans cells and antibody production in rodents.

In this study, we investigated whether stimulating the skin with ultrasound (US) could activate Langerhans cells (LCs) - antigen-presenting cells in the epidermis and stimulate antibody production following the subcutaneous and intradermal injection of ovalbumin (OVA) in hairless rats and BALB/c mice. Three different US frequencies (20 kHz, 1, and 3 MHz) were used and the expression of langerin was monitored as a marker for the activation of LCs in the epidermal sheet. In hairless rats, the langerin signal peaked at 12 h post-US treatment and returned to control levels at 24 h. Its expression increased with increasing irradiation time, up to 20 min, and 20 kHz US induced the highest langerin expression among the three frequencies tested. These results were reproduced in BALB/c mice. When the skin was pretreated with 20 kHz US at 0.41 W/cm2 for 10 min, the production of OVA-specific immunoglobulin G1 in mice increased by 2.8- and 3.4-fold 28 days after subcutaneous or intradermal OVA injections, respectively. These findings indicate that stimulating the skin with US can trigger skin immune responses, leading to effective antigen-specific antibody production. US-assisted transdermal vaccine delivery delivers antigens to the skin and evokes an immune response, providing an effective noninvasive immunization strategy.

Components Analysis of Bioactive Essential Oil Combinations (Lavender, Lemon, and Cinnamon) by Gas Chromatography-Mass Spectrometry and their Activities against In Vitro Photoaging on Hairless Rat Dorsal Skin

The essential oil of lavender, lemon, and cinnamon (LaLC) combination is rich in antioxidants and potentially be used as an anti-wrinkle and strengthens the collagen tissue. Ultraviolet B (UVB) radiation is a free radical source that accelerates the aging process and reduces collagen production. This study aims to characterize the chemical components of each oil and determine the best combination as an anti-wrinkle substance. The test was conducted on twenty-four Wistar male rats (Mus musculus) that were divided into six experimental groups consisting of the normal (N), control (C), vehicle control (V), first treatment (T1), second treatment (T2), and third treatment (T3) groups. Each sample was rubbed upon, and the UVB irradiation was administered frequently to each subject. The embedded skin specimen was analyzed using a digital-capable microscope. Data were analyzed through the Kolmogorov-Smirnov normality test, one-way analysis of variance (ANOVA), and the post-hoc Tukey's Honest Significant Difference test. Lavender, lemon, and cinnamon essential oils contained each most significant component, which was linalool (41.46% peak area), dl limonene (44.74% peak area), and 2-propenal, 3-phenyl- (CAS) (53.89% peak area), respectively according to the Gas Chromatography-Mass Spectrometry (GC-MS) analysis. The T1 showed the best score of all parameters and did not show significant significance compared to the N group. In conclusion, the 1:1:3 combination of LaLC is better in preventing in vitro photoaging than other treatment groups.

Novel topical esmolol hydrochloride improves wound healing in diabetes by inhibiting aldose reductase, generation of advanced glycation end products, and facilitating the migration of fibroblasts.

Aims/ObjectivesWound healing in people with diabetes is delayed secondary to impaired nitric oxide generation, advanced glycation end products (AGE), and poor migration of epithelial cells. We developed a novel topical esmolol hydrochloride (Galnobax) and assessed its efficacy for wound healing in streptozocin-induced diabetic hairless rat.MethodsAll experiments were performed at an animal laboratory and tertiary-care research facility. Ex vivo aldose reductase inhibition was assessed from enzymes obtained from a bacterial culture (spectrophotometer), sorbitol content in homogenized red blood cells, and AGE in glucose and bovine serum by fluorometry following the addition of esmolol in varying concentrations. A scratch assay of human fibroblasts, endothelial cells, and keratinocytes was assessed under a high-glucose environment and after esmolol by phase-contrast microscopy. The efficacy evaluation of the topical application of Galnobax (14 and 20%) or vehicle was conducted in streptozotocin-induced diabetic hairless rats, and endogenous nitrite and hydroxyproline from homogenized wound tissue were measured along with pharmacokinetic and dermal toxicity in Hanford miniature swine.ResultsEsmolol inhibited the formation of sorbitol by 59% in erythrocytes in comparison to glucose-induced sorbitol levels. AGE generation in bovine serum albumin was reduced at 1 mM esmolol concentrations (2.6 ± 1.7) compared with control (p < 0.05) and similar to that of diclofenac (2.5 ± 1.3). Esmolol at 1 and 10 µM enhanced the migration of fibroblasts, epithelial cells, and keratinocytes compared with control. The nitric oxide levels (day 7) were 44 and 112% higher with Galnobax (14%) than those of the diabetic group (p < 0.05) and the vehicle control group (p < 0.05), respectively. The days 7 and 14 hydroxyproline in the wound was higher by 22 and 44% following Galnobax (14%) compared with the diabetic and vehicle control groups. The wound area exhibited better reduction with Galnobax at 14% up to day 10 follow-up compared with the controls. The pharmacokinetic and dermal toxicity in miniature swine suggested no significant adverse event with Galnobax.ConclusionsTopical esmolol hydrochloride is a novel, safe, and effective treatment modality that acts through pleotropic mechanisms to hasten wound healing in diabetes.

Formulation and Evaluation of Transdermal Gel Containing Tacrolimus-Loaded Spanlastics: In Vitro, Ex Vivo and In Vivo Studies.

Our goal was to prepare Span 60-based elastic nanovesicles (spanlastics (SPLs)) of tacrolimus (TCR) using the adapted ethanol injection method, characterize them, and evaluate their ability to improve the transdermal permeation of the active substance. The impact of two different concentrations of penetration enhancers, namely, propylene glycol and oleic acid, on the entrapment efficiency, vesicle size, and zeta potential was assessed. Moreover, in vitro release through a semipermeable membrane and ex vivo penetration through hairless rat skin were performed. Morphological examination and pharmacokinetics were performed for one selected formulation (F3OA1). TCR-loaded SPLs were effectively formulated with two different concentrations of permeation enhancers, and the effect of these enhancers on their physicochemical properties differed in accordance with the concentration and kind of enhancer used. The results of in vitro release displayed a considerable (p < 0.05) enhancement compared to the suspension of the pure drug, and there was a correlation between the in vitro and ex vivo results. The selected TCR-loaded nanovesicles incorporated into a gel base showed appreciable advantages over the oral drug suspension and the TCR-loaded gel. Additionally, the pharmacokinetic parameters were significantly (p < 0.05) improved based on our findings. Moreover, the AUC0–7 ng·h/mL form F3 OA1 was 3.36-fold higher than that after the administration of the TCR oral suspension.

Comparative Evaluation of Safety and Efficacy of a Novel Hyaluronic Acid-polynucleotide/Poly-L-lactic Acid Composite Dermal Filler

Poly-L-lactic acid (PLLA) is widely used in tissue engineering. The natural polymer hyaluronic acid (HA) shows excellent biocompatibility and affects cell signaling, proliferation, and differentiation. In addition, a polynucleotide (PN) induces cell growth of human skin fibroblasts and osteoblasts. In this study, we evaluated the properties, safety, and efficacy of a novel composite filler consisting of cross-linked HA with PN in combination with monodisperse PLLA microspheres manufactured using Inventage Lab Precision Particle Fabrication method. The composition of the filler and characteristics of the microspheres were examined via scanning electron microscopy, particle size analysis, gel permeation chromatography, and rheology and osmolality measurement. Additionally, safety and efficacy of HA-PN/PLLA composite filler were conducted in in vitro and in vivo. Analysis of PLLA microspheres revealed spherical surfaces and a narrower particle size distribution than that in PLLA filler. HA-PN/PLLA composite filler had higher viscosity and elasticity values and similar osmolality as compared to those of HA and PN fillers. The nontoxicity in in vitro and in vivo tests reflected that the composite filler may be safe for human use. In addition, the composite filler maintained a more stable volume than did HA filler for 24 weeks after administration in HWY/Slc hairless rats. Furthermore, the results support the effect of HA-PN/PLLA in restoring skin structure. Altogether, these data suggest that the novel composite filler might be a safe and effective option in terms of tissue integration, clinical management during delivery and high esthetic durability. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

ACUTE AND CHRONICAL BIOLOGICAL EFFECTS OF W BAND MILLIMETRIC WAVES EXPOSURE IN RATS

The biological effects of millimetric waves systems, MMW (e.g. 5G communications, automotive radars, or crowd control systems, ADS) systems are still scarcely investigated. Hairless rats were exposed to 2 94GHz continuous wave (MMW, CW), under acute high power conditions (3sec at10kW/m ) and under 2 environmental/professional lower power exposure (4 hours a day, for 5 days a week, for 6 months at 10mW/cm ). It was found that the 94 GHz acute exposure provoked the disappearance of the epidermis upper corneal layers and the increase of the inammatory gene expression SOCS-3 after 3Hrs. Besides, neither histological nor genetic modication could be observed after chronic 94 GHz exposure and after an acute and a chronic capsaicin exposure. Conclusions :After a powerful acute exposition a thermal effect is observable, associated with a localized inammatory response. After chronic, low power exposition, an hypoalgesia effect was found, possibly related with an increase in brain plasticity. Mechanistically, the hypothesis is based on low noise stimulation of thermal pain receptors at subthreshold level. Conversely, neither inammation nor no direct change in was found.

Formulation development and evaluation of drug-in-adhesive-type transdermal patch of metoclopramide HCl

The objective was to design and develop a drug-in-adhesive-type transdermal patch formulation of metoclopramide HCl, which is used as an effective antiemetic, dopaminergic antagonist agent. In DIA patches, drug is directly embedded in the polymeric adhesive layer and permeates through the skin to provide systemic effect, avoiding gastrointestinal tract complications, including the first-pass metabolism. Six different patch formulations were prepared by a solvent evaporation method using varying metoclopramide HCl concentrations using acrylate polymer DURO-TAK® 387/2510 for adhesive support. In vitro permeation profiles and parameters were obtained by using the skin of hairless albino Wistar rats. The influence of drug content on the rate of permeation was investigated, and patch formulation was optimized based on Q12, flux, and lag time. The effect of permeation enhancers (EO and PG) on the permeation rate of metoclopramide HCl was also studied. The skin irritation study was performed to observe the hypersensitivity against the patch component. Stability studies of the optimized formulation of a transdermal patch for three months at three different temperatures were investigated. The transdermal patch formulation containing 10% w/w metoclopramide HCl was capable of effectively delivering metoclopramide HCl for systemic effect without any skin irritation. It has Q12 of 3.892 ± 0.0043 mg/cm2, flux rate of 0.2501 mg/cm2 h, and the coefficient of permeability of 6.25E−02 cm/h with a lag time of 0.442 h. The stability data revealed that the optimized patch formulation could be stored at 4 °C in the refrigerator with a shelf life of 3.53 months. This newly developed metoclopramide transdermal DIA patch is an effective alternative to oral delivery with desirable antiemetic activity.

Enhancement of Skin Permeation of a Hydrophilic Drug from Acryl-Based Pressure-Sensitive Adhesive Tape

Penetration enhancers are necessary to overcome a formidable barrier function of the stratum corneum in the development of topical formulations. Recently, non-lamella liquid crystal (NLLC)-forming lipids such as glycerol monooleate and phytantriol (PHY) are gaining increasing attention as a novel skin permeation enhancer. In the present study, fluorescein sodium (FL-Na) was used as a model hydrophilic drug, and acryl-base pressure-sensitive adhesive (PSA) tape containing NLLC forming lipids, mono-O-(5,9,13-trimethyl-4-tetradecenyl) glycerol ester (MGE) or PHY, was prepared to enhance drug permeation through the skin. A PSA patch containing FL-Na was prepared by mixing FL-Na entrapped in NLLC and acrylic polymer. FL permeation through excised hairless rat skin, and also human skin, was investigated. Changes in lipid structure, folding/unfolding state of keratin in the stratum corneum, and penetration of MGE into the stratum corneum were investigated using confocal Raman microscopy. Enhanced FL permeation was observed by the application of a PSA patch containing MGE and PHY. Especially, dramatically enhancement effect was confirmed by 15% of MGE contained formulation. Penetration of MGE provided diminished orthorhombic crystal structure and a peak shift of the aliphatic CH3 vibration of keratin chains toward lower wavenumbers. The present results suggested that the formulation development by adding MGE may be useful for improving the skin permeation of mal-permeable drugs such as hydrophilic drugs.

Pharmacological evaluation and safety of a donepezil patch.

Our aim was to assess the feasibility of transdermal delivery of donepezil and evaluate the pharmacokinetics (PK), pharmacodynamics (PD), and safety of donepezil patch in vitro and in vivo. Donepezil patches were applied to the skin of rabbits and humans for 7 days, then, the PK profiles were observed in a dose-dependent manner. Donepezil was continuously released from the patch for 7 days as compared to oral administration in hairless rats and rabbits. In hairless rats, peak acetylcholinesterase (AChE) inhibition of 34.7±2.0% was observed within 8 h after oral administration of 4 mg/head donepezil, and lasted for less than 24 h, consistent with changes in the plasma donepezil concentration. Peak AChE inhibition by the donepezil patch was equivalent to that in the orally administered group. Donepezil was released continuously from the patch for 7 days with a linear PK in both rats and rabbits. AChE activity inhibition was dependent on donepezil plasma concentration. The data exhibited excellent PK/PD correlation. There was no dermal irritation (erythema/edema) in placebo or donepezil patch group during the study period in minipigs. Thus, Dong-A's donepezil patch appeared to be generally safe and was well tolerated.

Novel Recombinant Tropoelastin Implants Restore Skin Extracellular Matrix

Elastin is an essential component of the dermis, providing skin with elasticity and integrity. Elastin and other dermal components are gradually lost through aging, sun damage, and following injury, highlighting a need to replace these components to repair the skin. Tropoelastin (TE) in monomeric form was previously shown to be utilized as a substrate by dermal fibroblasts during the production of elastin fibers in vitro. To analyze coaccumulation of elastin and collagen and gene expression of biomarkers associated with elastin production, examine the ex vivo effects of recombinant human TE (rhTE) and hyaluronic acid (HA) on epidermal and dermal structures, and evaluate the in vivo response following intradermal injections of rhTE and HA. Human dermal fibroblasts and 3-D skin patch models were cultured for in vitro analysis. Ex vivo analysis was performed using skin explants. In vivo studies were done in 6-week-old male CD Hairless rats. Different formulations of rhTE, soluble or crosslinked using derivatized HA (dHA), were tested and analyzed. rhTE in monomeric form was utilized as a substrate by dermal fibroblasts during the production of branched elastin and fibrous collagen networks in vitro. Formulations of rhTE crosslinked with dHA demonstrated increased expression of hyaluronic acid synthase 1 and ex vivo results revealed increased moisture content and glycosaminoglycan (GAG) deposition versus dermal filler control. Intradermal rhTE‒dHA injection produced colocalized human‒rat elastin fibers in vivo. These results suggest that the novel rhTE‒dHA matrix is an attractive material to support skin tissue repair.J Drugs Dermatol. 2020;19(12): doi:10.36849/JDD.2020.5375.