Association of urodynamics and lower urogenital tract nerve growth factor after synthetic vaginal mesh implantation on a rat model.

AIM: By investigating the association of urodynamics and urogenital nerve growth factor (NGF) levels in vaginal mesh surgery, we may be able to associate the likelihood of postoperative lower urinary tract symptoms developing as a result of synthetic mesh implanted for pelvic floor reconstructive surgery. METHODS: Thirty-eight female Sprague-Dawley rats were divided into three groups: mesh, sham (no mesh), and control. Urodynamic study and NGF analysis of the urogenital tissues were done and results were compared among all groups. The urodynamic studies of the mesh and sham groups were further divided into the 4th and 10th days. A P-value < 0.05 was considered statistically significant. RESULTS: All rats survived and no complications were observed during the post-implantation period. Histological evaluation showed intense acute inflammatory reaction on days 4 and 7 in the mesh and sham groups when compared to the control. The mesh group showed a larger area of inflammation as compared to the sham. The NGF levels increased significantly in the mesh and sham groups on the 4th and 10th days when compared to the control (P < 0.001, P < 0.001, respectively). Both the mesh and sham groups had shorter voiding interval and lower voiding volume on days 4 and 10 when compared to the control group (P < 0.001, P < 0.001, respectively). The magnitude on increasing NGF level and decreasing voiding interval and voiding volume was significantly more on the mesh group than the sham group. CONCLUSION: A higher level of NGF in the early days post-transvaginal mesh implantation is associated with a shorter voiding interval and a smaller bladder capacity, which represents abnormal lower urinary tract symptoms following transvaginal mesh implantation.

Proline cis-trans isomerization and its implications for the dimerization of analogues of cyclopeptide stylostatin 1: a combined computational and experimental study.

Cis and trans proline conformers are often associated with dramatic changes in the biological function of peptides. A slow equilibrium between cis and trans Ile-Pro amide bond conformers occurs in constrained derivatives of the native marine cyclic heptapeptide stylostatin 1 (cyclo-(NSLAIPF)), a potential anticancer agent. In this work, four cyclopeptides, cyclo-(NSTAIPF), cyclo-(KSTAIPF), cyclo-(RSTAIPF) and cyclo-(DSTAIPF), which are structurally related to stylostatin 1, are experimentally and computationally examined in order to assess the effect of residue mutations on the cis-trans conformational ratio and the apparent capacity to form dimeric aggregates. Primarily, cyclo-(KSTAIPF) and cyclo-(RSTAIPF) showed specific trends in circular dichroism, MALDI-TOF and HPLC purification experiments, which suggests the occurrence of peptide dimerization. Meanwhile, the NMR spectrum of cyclo-(KSTAIPF) indicates that this cyclopeptide exists in the two slow-exchange families of conformations mentioned above. Molecular dynamics simulations combined with quantum mechanical calculations have shed light on the factors governing the cis/trans conformational ratio. In particular, we have found that residue mutations affect the internal hydrogen bond pattern which ultimately tunes the cis/trans conformational ratio and that only trans conformers are capable of aggregating due to the shape complementarity of the two subunits.

Self-assembled trityl radical capsules--implications for dynamic nuclear polarization.

A new class of guest-induced, bi-radical self-assembled organic capsules is reported. They are formed by the inclusion of a tetramethylammonium (TMA) cation between two monomers of the stable trityl radical OX63. OX63 is extensively used in dissolution dynamic nuclear polarization (DNP) where it leads to NMR sensitivity enhancements of several orders of magnitude. The supramolecular properties of OX63 have a strong impact on its DNP properties. An especially relevant case is the polarization of choline-containing metabolites, where complex formation between choline and OX63 results in faster relaxation.

Comparison between Elevate anterior/apical system and Perigee system in pelvic organ prolapse surgery: clinical and sonographic outcomes.

OBJECTIVE: The aim of this study was to assess the incidence of de novo stress urinary incontinence (SUI) and sonographic features of implanted transvaginal mesh in continent women treated with Elevate(™) anterior/apical [single-incision mesh (SIM-A)] or Perigee(™) [transvaginal mesh with sacrospinous fixation (TVM + SSF)] in extensive pelvic organ reconstruction surgery. METHODS: This prospective observational study was done from May 2010 to January 2013. Patients were recruited from two tertiary centers, and the Elevate(™) and Perigee(™) systems were compared. Patients who had overt or occult SUI, previous prolapse or mesh insertion were excluded. RESULT: Fifty-seven patients in the SIM-A group and sixty-one in the TVM + SSF group were analysed. All completed a minimum of 1-year follow-up. Groups were demographically and statistically similar. There was a significantly high incidence of de novo SUI postoperatively in the SIM-A group. The objective and subjective cure rate of pelvic organ prolapse (POP) were comparable between groups, with incidence of mesh erosion in the SIM-A group and three in the TVM + SSF group. Sonographic evaluation showed significant increase in mesh length in the SIM-A group. CONCLUSION: Elevate(™) a offered lower incidence of mesh erosion and comparable results on anatomical POP correction; however, incidence of de novo SUI was high. There is an apparent lengthening of implanted Elevate® mesh sonographically.

Anterior-apical single-incision mesh surgery (SIMS): surgical and functional outcomes at 1 year.

STUDY OBJECTIVES: To study the surgical and functional outcomes of single-incision mesh surgery for treatment of advanced pelvic organ prolapse (POP). DESIGN: Case series (Canadian Task Force classification II-3). SETTING: University hospital. PATIENTS: Sixty-five patients who underwent surgery to treat symptomatic POP greater than stage II according to the Pelvic Organ Prolapse Quantification System (POP-Q). INTERVENTION: All patients underwent anterior-apical single-incision mesh surgery using the Elevate Anterior and Apical Prolapse Repair System. MEASUREMENTS AND MAIN RESULTS: The primary objectives were anatomical correction of anterior and apical prolapse of POP stage I or greater and absence of voiding dysfunction reported via multi-channel urodynamic study at 6 months after surgery. Subjective outcome was measured via patient feedback using questions 2 and 3 of the Pelvic Organ Prolapse Distress Inventory 6 (POPDI-6). The secondary outcome was quality of life using the following: Urogenital Distress Inventory 6 (UDI-6), Incontinence Impact Questionnaire 7 (IIQ-7), POPDI-6, and Pelvic Organ Prolapse/Urinary Incontinence Sexual Questionnaire (PISQ-12). Two-dimensional introital ultrasonography was performed in the first and third months after surgery and at 1-year follow-up. Descriptive statistics were used for demographic and perioperative data. The paired-samples t test was used for comparison of preoperative and postoperative continuous data. For all comparisons, a value of p < .05 was considered statistically significant. All statistical methods were performed using commercially available software (SPSS version 17). Postoperative data were available for 64 patients. The objective outcome was 96.9%, and the subjective outcome was 93.8%. All patients demonstrated significant improvement in anatomical outcomes after prolapse surgery (p < .05), and none experienced recurrence requiring further surgery. There was concomitant significant improvement in POPDI-6, UDI-6, IIQ-7, and PISQ-12 scores after surgery. A subanalysis of POP quantification measurements immediately after surgery and at 1-year postoperative follow-up demonstrated deepening of the C point and total vaginal length. Ultrasound evaluation demonstrated a significant increase in the length and thickness of mesh at 1-year follow-up. There has been no documented mesh extrusion to date. However, the number of patients with stress urinary incontinence has increased. Four patients received treatment, whereas in the remaining patients the condition was not severe enough to require surgical intervention. CONCLUSIONS: Single-incision mesh surgery for treatment of advanced POP results in improvement in anatomical and quality-of-life outcomes. No mesh exposure was recorded in the first year after surgery; however, new onset of stress urinary incontinence may occur. Ultrasound evaluation demonstrated an increase in mesh length and thickness over time, with concurrent calculated lengthening of the C point and total vaginal length.

Outcome after conservative management for mixed urinary incontinence.

AIM: Recommended initial treatment for mixed urinary incontinence involves behavioral therapy, and drug and pelvic floor muscle exercises. Our objective is to evaluate the outcome of these conservative treatments in our patients with mixed urinary incontinence. METHODS: A retrospective review was conducted in patients with mixed urinary incontinence who were offered sequential conservative treatment modalities comprised of medication and physiotherapy. Outcome was defined as a score of 1 or less for questions 2 and 3 on the six-item Urodynamic Distress Inventory (UDI-6) and seven-item Incontinence Impact Questionnaire, in addition to clinical symptomatic improvement with no urgency, urge incontinence and voiding frequency of less than eight times per 24 h on a 3-day bladder diary after treatment. Treatment outcome of patients opting for medication plus physiotherapy (M + P) were analyzed against patients preferring medication only (M). RESULTS: Sixty-two mixed urinary incontinent patients received an initial treatment with conservative measures with mean follow-up of 14 months. A total of 61.2% (30/49) and 56.3% (9/13) subjects had improved symptoms in the M + P and M group, respectively. There was significant improvement in UDI-6 total score in the M + P group after conservative treatment, despite no significant difference when compared to the M group. Only 6.45% required subsequent anti-incontinence surgery after conservative treatment, amongst whom only half showed improvement after the surgery. CONCLUSION: Combined treatment with medication and physiotherapy is highly recommended for patients with mixed urinary incontinence. Conservative measures should still precede any surgical intervention. Further studies are needed to evaluate the long-term efficacy.

Clinical outcomes of mesh exposure/extrusion: presentation, timing and management.

BACKGROUND: The Food and Drug Administration has recently highlighted an increase in reported complications associated with the use of transvaginal mesh. AIMS: To describe the clinical outcomes, presentation, timing and management of mesh exposure/extrusion MATERIALS AND METHODS: Retrospective study from December 2006 to March 2012. A total of 40 women had vaginal mesh exposure/extrusion secondary to prior transvaginal mesh (TVM) surgery. Descriptive statistics were used for demographics and pre-operative data. Paired-samples t-test was applied for comparison of pre- and postoperation. A P value of <0.05 was considered statistically significant. RESULTS: The mesh exposure/extrusion rate was noted to be 2.64% (17/642). Vaginal bleeding in 29 of 40 (72.5%) and hispareunia in 12 of 13 (92.3%) were identified as the most common symptoms for mesh exposure/extrusion. The onset of complications occurred in two peaks: between 3 and 4 months and after 1-year of follow-up. Initial conservative treatment was given for 12.5% (5/40) of women, while 87.5% (35/40) had undergone repair for mesh exposure/extrusion (21 outpatient and 14 inpatient cases). Among those who had conservative treatment, 80% (4/5) had persistent mesh exposure. CONCLUSION: Persistent or new-onset abnormal vaginal bleeding and hispareunia after TVM surgery should be considered as 'red flag' symptoms for mesh exposure/extrusion. Frequent follow-up from the first 3-4 months up to 1 year postoperative may identify complications. Utilisation of mesh excision or trimming as the initial means of treatment may yield a better outcome.

Assessment of collagen-coated anterior mesh through morphology and clinical outcomes in pelvic reconstructive surgery for pelvic organ prolapse.

STUDY OBJECTIVE: To assess the morphologic features of anterior armed transobturator collagen-coated polypropylene mesh and its clinical outcomes in pelvic reconstructive surgery to treat pelvic organ prolapse. DESIGN: Evidence obtained from several timed series with intervention (Canadian Task Force classification II-3). SETTING: Chang Gung Memorial Hospital, Taoyuan, Taiwan, China. PATIENTS: Between April 2010 and October 2012, 70 patients underwent surgery to treat symptomatic pelvic organ prolapse, stage III/IV according to the POP-Q (Pelvic Organ Quantification System). INTERVENTION: Anterior armed transobturator collagen-coated mesh. MEASUREMENT AND MAIN RESULTS: Morphologic findings and clinical outcome were measured. Morphologic features were assessed via 2-dimensional introital ultrasonography and Doppler studies. Clinical outcome was measured via subjective and objective outcome. Objective outcome was assessed via the 9-point site-specific staging method of the International Continence Society Pelvic Organ Prolapse Quantification before the operation and at 1-year postoperative follow-up. Subjective outcome was based on 4 validated questionnaires: the 6-item UDI-6 (Urogenital Distress Inventory), the 7-item IIQ-7 (Incontinence Impact Questionnaire), the 6-item POPDI-6 (Pelvic Organ Prolapse Distress Inventory 6), and the 12-item PISQ-12 (Pelvic Organ Prolapse/Urinary Incontinence Sexual Questionnaire), at baseline and at 12 months after the operation. Data were obtained for 65 patients who underwent the combined surgery and were able to comply with follow-up for >1 year. Ultrasound studies reveal that mesh length tends to shorten and decrease in thickness over the 1-year follow-up. Vagina thickness also was reduced. Neovascularization through the mesh was observed in <8.5% of patients in the first month and at 1 year, and was evident in approximately 83%. The mesh exposure rate was 6.4%. The recorded objective cure was 90.8% (59 of 65 patients), and subjective cure was 89.2% (58 of 65 patients) at mean (SD) follow-up of 19.40 (10.98) months. At 2 years, UDI-6, IIQ-7, and POPDI-6 scores were all significantly decreased (p < .001), whereas the PISQ-12 score was significantly increased (p = .01). CONCLUSIONS: Ultrasound features suggest that the degeneration of collagen barrier may be longer than expected and that integration of collagen-coated mesh could occur up to 1 year. A substantially good clinical outcome was noted.

Use of high-pressure freeze fixation and freeze fracture electron microscopy to study the influence of the phospholipid molar ratio in the morphology and alignment of bicelles.

The high-pressure freeze fixation and freeze fracture electron microscopy techniques were combined with the (31)P nuclear magnetic resonance to study the morphological transitions of two different dimyristoyl-phosphatidilcholine/dihexanoyl-phosphocholine aggregates by the effect of temperature. Through these techniques, the relationship between magnetic alignment and the morphology of alignable and non-alignable aggregates was evaluated. The micrographs related to the non-alignable dimyristoyl-phosphatidilcholine/dihexanoyl-phosphocholine sample presented rounded objects at a temperature below the dimyristoyl-phosphatidilcholine phase transition (T(m)) and, above this temperature an increase of viscosity was followed by the appearance of large elongated aggregates. The micrographs related to the alignable dimyristoyl-phosphatidilcholine/dihexanoyl-phosphocholine sample presented discoidal objects below T(m). Above T(m), when the best alignment was achieved, the images showed large areas of lamellar stacked bilayers and the presence of some multilamellar vesicles. Our results reveal that the composition of the aggregates is a key factor determining the morphological transitions of the bicellar systems. Understanding of the rules governing these transitions is crucial to modulate characteristics of these systems and to adequate them for different applications.

Resonance energy transfer in the solution phase photophysics of -Re(CO)3 L+ pendants bonded to poly(4-vinylpyridine).

Polymers with general formula ([(vpy) 2vpyRe(CO) 3(tmphen) (+)]) n ([(vpy) 2vpyRe(CO) 3(NO 2-phen) (+)]) m (NO 2-phen = 5-nitro-1,10-phenanthroline; tmphen = 3,4,7,8-tetramethyl-1,10-phenanthroline); vpy = 4-vinylpyridine) were prepared and their morphologies were studied by transmission electron microscopy (TEM). Multiple morphologies of aggregates from these Re I polymers were obtained by using different solvents. Energy transfer between MLCT Re-->tmphen and MLCT Re-->NO 2 -phen excited states inside the polymers was evidenced by steady state and time-resolved spectroscopy. Current Forster resonance energy transfer theory was successfully applied to energy transfer processes in these polymers.

Clinical Relevance and Treatment Selection of Ureteral Injury After Cesarean Section.

INTRODUCTION: The aim of this case series was to report the clinical relevance and management outcomes of ureteral injuries acquired secondary to cesarean section. METHODS: This was a retrospective case series from January 2007 to September 2014. Description of the patients' characteristics, diagnostic tools for investigation, management, and postoperative follow-up was conducted on postcesarean section patients who developed symptoms of urine leakage after cesarean section and necessitated secondary surgery for ureteral injury. Descriptive statistics was used for demographics and operative data. RESULTS: A total of 5619 cases were managed by cesarean section during the study period. Six (0.107%; 95% confidence interval [CI], 0.1069%-0.1071%) patients had ureteral injury related to the cesarean section. Of 6 cases, 3 (0.053%; 95% CI, 0.0529%-0.0531%) had ureterouterine fistula. Three cases were managed by ureteroneocystostomy, 1 by ureteroneocystostomy with Boari flap, 1 by transureteroureterostomy, and the other one by ureteral stenting via ureterocystoscopy. Three patients had immediate operation because of an acute abdomen and 3 patients had delayed operation. The left ureter was the most common site of ureteral injury (5/6). The postoperative course was uneventful for all cases. CONCLUSIONS: Continuous urinary leakage and acute abdominal distention associated with fluid accumulation after emergency cesarean section should be considered as "red flag" symptoms of ureteral injury and ureterouterine fistulae complications. Delayed management for ureteral repair may not be associated with bad outcomes for management of ureterouterine fistula. Delayed management was associated with less blood loss, less operating time, and acceptable outcome among patients with ureterouterine fistulae when the renal function is not compromised.

Assessment of collagen versus non collagen coated anterior vaginal mesh in pelvic reconstructive surgery: prospective study.

OBJECTIVE: To evaluate the sonologic and clinical outcome of collagen coated (CC) versus non-collagen coated (NC) anterior vaginal mesh (AVM) for pelvic organ prolapse (POP) surgery. STUDY DESIGN: The study is a prospective observational study which included 122 patients who had symptomatic POP stage III and IV. AvaultaPlus™ (collagen coated, CC group) was compared to Perigee™ (non collagen coated, NC group). Introital ultrasound morphology, measure of neovascularization by color Doppler and clinical outcomes were assessed. Student t test was used for comparison of pre- and post-operation continuous data (p value of <0.05). RESULTS: A total of 110 (CC group=50, NC group=60) women completed the study. A woman in the CC group developed ureteral injury. Both groups had comparable morphologic and clinical outcomes however, the onset of changes in mesh thickness and neovascularization occurred earlier in the NC group (1 month) compared to the CC group (6 months to 1 year). CONCLUSION: CC group was comparable to the NC group in terms of erosion rate, ultrasound and clinical assessment. Collagen coating may induce delayed inflammatory response however may also delay tissue integration. The onset of changes in mesh thickness and neovascularization may give us an insight toward utilization of collagen coated mesh for host-tissue integration.

Surface changes induced by osmotic stress and its influence on the glycerol permeability in lipid bilayers.

The penetration rate of glycerol across lipid bilayers can be assayed dispersing liposomes filled with a 0.1 M glucose solution in an isotonic or a hypertonic solution of glycerol. The kinetic of glycerol permeation is found to be different in each of those cases. Liposomes dispersed above the phase transition temperature in hypertonic solutions show an increase in the surface polarization as measured by means of merocyanine 540. Under this condition, the permeation of glycerol shows a two-step kinetic which is indicative of a non-fickean diffusion process. In contrast, liposomes dispersed in isotonic solutions of the permeant show a fickean behavior. The changes in polarization of the membrane interface are ascribed to variations in the surface potential due to the osmotic collapse and the glycerol concentration in contact with the outer surface. The permeability of polar molecules can, in consequence, be considered as a function of the surface potential of the liposome which is congruent with previous data in literature reporting that water permeability increases as a function of the zeta potential of liposomes shrunken in hypertonic solutions.

Effect of dolichyl monophosphate on the permeability properties of lipid membranes.

The effect of dolichyl monophosphate on the permeability properties of dimyristoylphosphatidylcholine bilayers to alkaline cations, Ca2+ and glucose has been determined by stop-flow spectrophotometry. The results show that, in contrast to free dolichol effects, the monophosphate derivative increased the permeability following a decreasing order of the permeating particle size. Phase diagrams indicate that dolichyl monophosphate is fully incorporated into the phosphatidylcholine bilayer around 0.75% weight/weight ratio. For these ratios, the permeation of ions is higher in the gel than in the liquid crystalline state.

Properties of gel phase lipid-trehalose bilayers upon rehydration.

When dipalmitoylphosphatidylcholine bilayers dried under vacuum in different concentrations of trehalose are rehydrated in buffer without the sugar they show different physicochemical properties in the gel state in comparison to the normal gel state. Dry DPPC/trehalose mixtures are readily dispersed in buffer below the phase transition showing by electron microscopy a morphology similar to liposomes prepared by dispersing the lipids in buffer above the phase transition temperature. In these conditions, an increase in the peak at 570 nm of merocyanine after the dehydration-rehydration process in the presence of the sugar is observed and the water permeation increases to values comparable to those found in the fluid state as indicated by the activation energy values and the osmotic volume. The trehalose-dried liposomes rehydrated in buffer show a similar osmotic response to hypertonic gradient as DPPC liposomes without sugar near the phase transition temperature. In accordance with this behavior the trehalose-dried liposomes are lysed below the phase transition temperature by lysoderivatives. These modifications of the gel state of hydrated phospholipids by trehalose can only be achieved if a drastic dehydration is performed in the presence of the sugar. After rehydration the changes in the gel state can be detected after dyalizing the rehydrated membranes in media without trehalose during at least 24 h. These results suggest that trehalose is still intercalated between the phospholipids after restoring water to the dried liposomes either at temperatures below or above the phase transition.

Charge-Transfer Processes in (4-Nitrobenzoate)Re(CO)(3)(azine)(2) Complexes. Competitive Reductions of 4-Nitrobenzoate and Azine in Thermally and Photochemically Induced Redox Processes.

The photochemically and thermally induced redox reactions of the (4-nitrobenzoate)Re(CO)(3) (azine) (azine = 1,10-phenanthroline, 2,2'-bipyridine, and (4-phenylpyridine)(2)) were investigated by flash photolysis and pulse radiolysis. Processes characterized as intramolecular charge transfers from coordinated azine radicals to the 4-nitrobenzoate ligand and vice versa were observed in a 1-100 &mgr;s time scale by pulse radiolysis. In photochemical experiments, the conversion among metal to ligand charge-transfer excited states, i.e., from the Re to azine to the Re to 4-nitrobenzoate charge-transfer excited state, involves intermediates with lives of picoseconds. A mechanism for the conversions that incorporates intraligand excited states is discussed.

The effect of dolichol on the permeability properties of phosphatidylcholine bilayers.

The permeability of liposomes to water, glucose, Ca2+ and alkaline cations was monitored by recording the change in absorbance at 450 nm using a rapid reaction stopped-flow spectrophotometer. Liposomes were prepared with egg phosphatidylcholine and concentrations of dolichol ranging from 0.1% to 9% (w/w). Net permeability of phosphatidylcholine bilayers to alkaline cations was induced by the incorporation of dolichol. This effect was not observed in the case of non-charged solutes like glucose or in that of alkaline earth cations such as calcium. Permeation of K+ was significantly increased above the phase transition temperature. These results suggest that dolichols may play a role in biological membranes, besides the well-known glycosyl carrier function in the biosynthesis of glycoproteins.

Ultrasonography and clinical outcomes following surgical anti-incontinence procedures (Monarc vs Miniarc).

OBJECTIVE: To evaluate the ultrasound morphology and its clinical outcome among women who had undergone Miniarc™ vs Monarc™ in the treatment of stress urinary incontinence (SUI). STUDY DESIGN: This was a prospective study on 140 patients with USI and undergone either Miniarc or Monarc surgery. From March 2010 to December 2011, patients with clinically SUI and urodynamic stress incontinence (USI) were included in the study. Objective cure of SUI was defined as no urinary leakage on provocative filling cystometry and 1-h pad test of <2 g. Subjective cure of SUI was the negative response to UDI-6. Introital ultrasound at one-year explored the sling and bladder neck's position, mobility, sling tension, percentile of urethra where the sling was located and urethral kinking. RESULTS: Postoperative data was available from 130 women. The ultrasound objective data for successful treatment post-operative follow-up was available from 119 women (46 Monarc, 73 Miniarc), the rest failed to follow-up. A bladder perforation was diagnosed in the Monarc group and 15 cases (7.1% of Monarc and 16.3% of Miniarc, p=0.082) of urinary retention was reported due to over-tensioning of the sling, majority of cases came from the Miniarc group. At rest and during Valsalva, analogous distances of the bladder neck and sling as well as the center of the urethral core were similar for both procedures. In both groups, shortest (Us) and longest diameters (Ul) of the urethral core were comparable at Valsalva which was significantly shorter and longer, respectively, compared to the values at rest. Sling position and percentage of urethral kinking were similar. Statistical analysis failed to detect any significant difference between the two groups with regards to the objective and subjective cure (p>0.05). CONCLUSIONS: In conclusion, a Miniarc and Monarc exhibit similar mechanism of action with comparable subjective and objective clinical outcomes. Majority of urethral impingement was noted in the Miniarc group. A higher maximum urethral closure pressure (MUCP), longer resting Ul, and shorter resting Us suggested these observations. Postoperative ultrasonographic evaluation may give a promising future perspective for the evaluation of sling tension.

Penetration and growth of DPPC/DHPC bicelles inside the stratum corneum of the skin.

The effect of dipalmitoyl phosphatidylcholine (DPPC)/dihexanoyl phosphatidylcholine (DHPC) bicelles on the microstructure of pig stratum corneum (SC) in vitro was evaluated. The physicochemical characterization of these nanoaggregates revealed small disks with diameters around 15 nm and a thickness of 5.4 nm. Upon dilution, the bicelles grow and transform into vesicles. Cryogenic scanning electron microscopy (cryo-SEM) images of the SC pieces treated with this system showed vesicles of about 200 nm and lamellar-like structures in the intercellular lipid areas. These vesicles probably resulted from the growth and molecular rearrangement of the DPPC/DHPC bicelles after penetrating the SC. The presence of lamellar-like structures is ascribed to the interaction of the lipids from bicelles with the SC lipids. The bicellar system used is suitable to penetrate the skin SC and to reinforce the intercellular lipid areas, constituting a promising tool for skin applications.