[Functional evaluation and quality of life in megaprostheses implanted by musculoskeletal tumors in the lower limb]. / Evaluación funcional y calidad de vida en megaprótesis implantadas por tumores musculoesqueléticos en miembro inferior.

INTRODUCTION: radical resection is the surgical treatment of choice in musculoskeletal malignancies, which often settle in the pelvis and lower limbs. Megaprothesis reconstruction has been imposed in recent years as the gold standard in limb preservation surgery. MATERIAL AND METHODS: descriptive retrospective study series of cases, including 30 patients operated between 2011 and 2019 of musculoskeletal pelvic and lower limb tumors at our institution that underwent limb-sparing reconstruction with the megaprosthesis. Functional results according to the MSTS (Musculoskeletal Tumor Society) index and complication rate were analyzed. RESULTS: the average follow-up was 40.8 months (12-101.7). Nine patients (30%) underwent pelvic resections and reconstructions, 11 patients (36.7%) underwent hip reconstruction with megaprothesis due to femoral involvement, in three patients (10%) complete femur resection was performed, and seven patients (23.3%) underwent prosthetic reconstruction of the knee. The mean MSTS score was 72.5% (range: 40-95%), and the complication rate was 56.7% (17 patients), being de tumoral recurrence (29%) the main complication. CONCLUSION: tumor megaprothesis give satisfying functional results, allowing the patients to realize a relatively normal life after a lower limb-sparing surgery.

INTRODUCCIÓN: la resección amplia es el tratamiento quirúrgico de elección en los tumores malignos musculoesqueléticos, que con frecuencia asientan en la pelvis y en los miembros inferiores. La reconstrucción mediante megaprótesis se ha impuesto en los últimos años como primera opción en la cirugía de preservación de la extremidad. MATERIAL Y MÉTODOS: estudio retrospectivo descriptivo serie de casos, incluye 30 pacientes intervenidos entre 2011 y 2019 de tumores musculoesqueléticos de pelvis y miembro inferior. En todos ellos valoramos la tasa de complicaciones y los resultados funcionales mediante el índice MSTS (Musculoskeletal Tumor Society). RESULTADOS: se realizó un seguimiento de 40.8 meses (12-101.7). En nueve pacientes (30%) se realizaron resecciones y reconstrucciones pélvicas, a 11 pacientes (36.7%) se les implantaron megaprótesis de cadera por afectación femoral, en tres de los pacientes (10%) se realizó resección del fémur completo y en siete pacientes (23.3%) reconstrucción protésica de la rodilla. El resultado funcional medio de la escala MSTS fue de 72.5% (rango: 40-95%) y la tasa de complicaciones de 56.7% (17 pacientes), siendo la recurrencia tumoral (29%) la principal complicación. CONCLUSIÓN: la reconstrucción mediante megaprótesis ofrece buenos resultados funcionales a los pacientes dentro de la cirugía de resección radical, permitiendo realizar una vida relativamente normal.

[Aneurysmal bone cyst located on the acetabular roof in an 11-year-old male]. / Quiste óseo aneurismático localizado en el techo acetabular en un varón de 11 años.

The aneurysmal bone cyst is a benign rare tumor, which usually develops during childhood and its more often found in limbs. The most accepted treatment consists in curetagge and filling with graft. However, certain locations may be inaccesible for surgery and represent therapeutical challenges. We present the case of an 11 year-old male patient with limping and right hip pain without any traumatic nor infectious record. In the image studies with CT and MRI a lytic and expansive lession was found in the upper part of the right acetabulum and right iliac wing, all of which suggested an aneurysmal bone cyst with an associated acetabular fracture. A biopsy was performed which confirmed the diagnosis. He was treated with a CT-guided embolization and, due to its size, curetagge and allograft filling afterwards. He was asymptomatic after1 year of follow-up.

El quiste óseo aneurismático es una tumoración benigna poco común, de aparición en la infancia generalmente y a nivel de extremidades. El tratamiento más habitual consiste en el curetaje y relleno con injerto. No obstante, localizaciones poco accesibles a la cirugía suponen un reto terapéutico. Se presenta el caso de un paciente de 11 años con cojera y dolor en cadera derecha sin antecedente traumático ni infeccioso. En los estudios de imagen con TAC y RM se evidencia una lesión lítica expansiva que ocupa todo el techo del acetábulo y pala ilíaca derecha, sugestiva de un quiste óseo aneurismático presentando fractura acetabular asociada. Se realizó una biopsia que confirmó el diagnóstico. Se trató mediante embolización guiada por angiografía debido al gran volumen y alto riesgo de fractura, después del curetaje y relleno con aloinjerto evolucionó satisfactoriamente y el paciente se encuentra asintomático al año de la intervención.

An antisense oligonucleotide targeting TGF-ß2 inhibits lung metastasis and induces CD86 expression in tumor-associated macrophages.

BACKGROUND: The transforming growth factor (TGF)-ß pathway is a well-described inducer of immunosuppression and can act as an oncogenic factor in advanced tumors. Several preclinical and clinical studies show that the TGF-ß pathway can be considered a promising molecular target for cancer therapy. The human genome has three TGF-ß isoforms and not much is known about the oncogenic response to each of the isoforms. Here, we studied the antitumor response to ISTH0047, a recently developed locked nucleic acid-modified antisense oligonucleotide targeting TGF-ß2. MATERIALS AND METHODS: We have studied the anticancer response to ISTH0047 using gymnotic delivery in tumor cell cultures and in in vivo preclinical orthotopic mouse models for primary tumors (breast and kidney tumors) and lung metastasis. RESULTS: We observed that ISTH0047 is able to significantly reduce TGF-ß2 mRNA and protein levels without altering the levels of TGF-ß1 and TGF-ß3. ISTH0047 prevented lung metastasis in syngeneic orthotopic renal cell carcinoma (RENCA) and breast cancer (4T1) tumor models. In addition, using an orthotopic xenograft model of a lung cancer cell line (CRL5807) that mainly expresses TGF-ß2, we observed that ISTH0047 had an important effect on the lung microenvironment inhibiting the growth of lung lesions. ISTH0047 treatment re-educated macrophages in the lung parenchyma to express the tumor-suppressive factor, CD86. CONCLUSION: Overall, our data point to TGF-ß2 as a therapeutic target and ISTH0047 as a novel anticancer drug to prevent lung metastasis by impacting on the tumor niche, in part, through the induction of CD86 in tumor-associated macrophages.

[Surgical treatment of malignant primary tumors of the pelvis on Ennekings zone II]. / Tratamiento quirúrgico de los tumores primarios malignos de pelvis de la zona II de Enneking.

INTRODUCTION: Surgical treatment of malignant bone tumors of the pelvis with periacetabular involvement is constantly evolving. Even though acetabular reconstructions improve quality of life without impairing cancer control, they are not complication free. Our purpose is to describe the functional outcomes and surgical complications of different reconstructive techniques for Enneking zone II tumors. MATERIAL AND METHODS: Fifteen patients underwent surgery for malignant pelvic bone tumors between 2002 and 2012. Seven patients were retrospectively evaluated according to the Enneking and Dunham classification and were found to have periacetabular involvement, as follows: 3 were type II; 1 types I + II; 2 types II + III, and one types I + II + III. Five patients had a standard chondrosarcoma and 2 osteosarcoma. Patients included 4 males and 3 females; mean age was 43 years. The minimum follow-up period was 12 months (mean 6.14 years). All of them underwent cancer resection with periacetabular reconstruction: massive osteochondral allograft in 3 patients, structural allograft and hip arthroplasty in 2 patients, and prosthesis with iliac anchoring in 2. They were clinically, radiologically and functionally evaluated with the MSTS scale (1993). RESULTS: The mean MSTS score 6 months after surgery was 20.71 (69%). Five patients (71.4%) had surgical complications: 2 dislocations of the native femoral head on the allograft; one aseptic prosthetic dislodgement, and 2 deep infections. All patients had free intraoperative borders. CONCLUSIONS: Acetabular reconstructions after oncologic resection for malignant bone tumors seem to provide good functional outcomes. However, only selected cases should undergo surgeries associated with a high complication rate.

El tratamiento quirúrgico de los tumores óseos malignos de pelvis con afectación periacetabular está en continua evolución. Las reconstrucciones acetabulares mejoran la calidad de vida sin perjudicar el control oncológico; sin embargo, no están exentas de complicaciones. Nuestro objetivo es describir los resultados funcionales y las complicaciones quirúrgicas de diferentes técnicas reconstructivas de la zona II de Enneking.

[Treatment of a recalcitrant hip infection with a vastus lateralis muscle flap]. / Tratamiento de la infección recalcitrante de cadera mediante colgajo de músculo vasto lateral.

BACKGROUND: Recalcitrant hip infection after arthroplasty presents a reconstructive challenge to orthopedic surgeons. The aim of this study is to evaluate the results with a vastus lateralis muscle flap used to treat these recalcitrant hip infections in our Department. MATERIAL AND METHODS: A retrospective descriptive study was conducted on five patients with deep hip infections by transposition of the vastus lateralis muscle flap. Average age: 70.5 years. Mean follow-up: 30 months (range, 25-34 months). All patients had previously undergone other major surgical procedures (mean of 3.7 previous procedures). All had multiple microbial infections before surgery. The pathogens involved using cultures of the fistula, the outcome of the wound and laboratory results, including C-reactive protein (CRP), were analysed. RESULTS: Healing was achieved in the five patients who underwent surgery without requiring any further procedures or inflammatory signs of infection. CRP returned to normal one month after surgery, and there was no morbidity or mortality related to surgical technique. CONCLUSION: In our experience, the vastus lateralis muscle flap as a treatment for recalcitrant deep infection after arthroplasty has presented good results, provided there is appropriate antibiotic therapy and surgical debridement, thus achieving wound healing and a return to normal of the CRP.

PI3K inhibition results in enhanced HER signaling and acquired ERK dependency in HER2-overexpressing breast cancer.

There is a strong rationale to therapeutically target the phosphatidylinositol 3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/AKT/mTOR) pathway in breast cancer since it is highly deregulated in this disease and it also mediates resistance to anti-HER2 therapies. However, initial studies with rapalogs, allosteric inhibitors of mTORC1, have resulted in limited clinical efficacy probably due to the release of a negative regulatory feedback loop that triggers AKT and ERK signaling. Since activation of AKT occurs via PI3K, we decided to explore whether PI3K inhibitors prevent the activation of these compensatory pathways. Using HER2-overexpressing breast cancer cells as a model, we observed that PI3K inhibitors abolished AKT activation. However, PI3K inhibition resulted in a compensatory activation of the ERK signaling pathway. This enhanced ERK signaling occurred as a result of activation of HER family receptors as evidenced by induction of HER receptors dimerization and phosphorylation, increased expression of HER3 and binding of adaptor molecules to HER2 and HER3. The activation of ERK was prevented with either MEK inhibitors or anti-HER2 monoclonal antibodies and tyrosine kinase inhibitors. Combined administration of PI3K inhibitors with either HER2 or MEK inhibitors resulted in decreased proliferation, enhanced cell death and superior anti-tumor activity compared with single agent PI3K inhibitors. Our findings indicate that PI3K inhibition in HER2-overexpressing breast cancer activates a new compensatory pathway that results in ERK dependency. Combined anti-MEK or anti-HER2 therapy with PI3K inhibitors may be required in order to achieve optimal efficacy in HER2-overexpressing breast cancer. This approach warrants clinical evaluation.

Lapatinib, a HER2 tyrosine kinase inhibitor, induces stabilization and accumulation of HER2 and potentiates trastuzumab-dependent cell cytotoxicity.

Lapatinib is a human epidermal growth factor receptor 2 (HER2) tyrosine kinase inhibitor (TKI) that has clinical activity in HER2-amplified breast cancer. In vitro studies have shown that lapatinib enhances the effects of the monoclonal antibody trastuzumab suggesting partially non-overlapping mechanisms of action. To dissect these mechanisms, we have studied the effects of lapatinib and trastuzumab on receptor expression and receptor signaling and have identified a new potential mechanism for the enhanced antitumor activity of the combination. Lapatinib, given alone or in combination with trastuzumab to HER2-overexpressing breast cancer cells SKBR3 and MCF7-HER2, inhibited HER2 phosphorylation, prevented receptor ubiquitination and resulted in a marked accumulation of inactive receptors at the cell surface. By contrast, trastuzumab alone caused enhanced HER2 phosphorylation, ubiquitination and degradation of the receptor. By immunoprecipitation and computational protein modeling techniques we have shown that the lapatinib-induced HER2 accumulation at the cell surface also results in the stabilization of inactive HER2 homo- (HER2/HER2) and hetero- (HER2/EGFR and HER2/HER3) dimers. Lapatinib-induced accumulation of HER2 and trastuzumab-mediated downregulation of HER2 was also observed in vivo, where the combination of the two agents triggered complete tumor remissions in all cases after 10 days of treatment. Accumulation of HER2 at the cell surface by lapatinib enhanced immune-mediated trastuzumab-dependent cytotoxicity. We propose that this is a novel mechanism of action of the combination that may be clinically relevant and exploitable in the therapy of patients with HER2-positive tumors.

Cosmetic effectiveness of topically applied hydrolysed keratin peptides and lipids derived from wool.

BACKGROUND/PURPOSE: Skin moisturisation, elasticity, feel and appearance can all be improved through the topical application of protein hydrolysates. Recent studies suggest that supplementing intercellular lipids of the stratum corneum can enhance the functioning of the skin. METHODS: In this study, a hydrolysed keratin peptide (molecular weight <1000 Da) was prepared from wool and tested on skin in two different formulations: an aqueous solution and an internal wool lipids (IWL) liposome suspension. In vivo long-term studies were performed to evaluate the water barrier function of the skin after topical application of different formulations. During the treatment period, hydration and elasticity were determined. A sorption-desorption test was also performed to assess the hygroscopic properties and water-holding capacity of the different treated skin sites. RESULTS: Significant differences were found between the control and treated sites, with the treated areas showing an increase in hydration and elasticity as a result of keratin peptide application. Measurements also indicated that the keratin formulations reinforce the skin barrier integrity, improving its water-holding capacity. CONCLUSION: A combination of the keratin peptide with the IWL showed beneficial effects, indicating that this combination is suitable for designing new cosmetics products.

Wool peptide derivatives for hand care.

Hands experience much greater wear and tear during normal daily routines compared with most other parts of the body, and thereby demand specific needs from cosmetics targeted at hand care. Keratin proteins are the major structural component of the outer layers of the skin. In this work a novel keratin fraction from wool, which has high cystine content present in the S-sulphonated form, has been developed to target hand care applications. In vivo long-term studies were performed to evaluate the water-holding capacity and elasticity of hand skin following topical application of keratins. Moreover, protection of healthy skin against detergent-induced dermatitis was evaluated after topical application of the keratin-active formulation. Significant results in the measured biophysical parameters were found, which indicated an improvement in the skin's water-holding capacity, hydration, and elasticity for volunteers with dry skin as a result of the keratin peptide treatment. Results also indicated that the keratin peptide treatment can prevent some of the damaging effects associated with surfactant exposure.

Percutaneous absorption of flavan-3-ol conjugates from plant procyanidins.

Catechins (flavanols) are strong antioxidants, free radical scavengers and inhibitors of lipid peroxidation. New bio-based antioxidant compounds obtained by depolymerization of plant polymeric flavanols (procyanidins) in the presence of cysteine or cysteamine, as well as their underivatized counterpart, (-)-epicatechin, were evaluated in terms of their percutaneous absorption profiles taking into account their free radical scavenging efficiency. The evaluation of the percutaneous absorption of flavanols was carried out by an in vitro methodology using both pig and human skin. A good correlation was obtained using both skins in the evaluation of the skin absorption profiles. It can be deduced that 4beta-(S-cysteinyl)epicatechin (Cys-Ec) has a tendency to be located mainly in the outermost layers of the skin, whereas 4beta-(2-aminoethylthio)epicatechin (Cya-Ec) has a pronounced percutaneous absorption capacity. Their antioxidant properties and their skin penetration profiles support their potential cosmetic or pharmacological applications.

Diagnostic laparoscopy.

Since the early part of the 20th century, diagnostic laparoscopy has become an important tool in the armamentarium of surgeons and gastroenterologists alike. Its indications have expanded from initial attempts at tamponading internal hemorrhage to avoidance of unnecessary laparotomies with accurate staging of malignancies, treatment of a multitude of intra-abdominal pathologies, and even as a resource for evaluating blunt abdominal trauma and chronic abdominal pain. Its accuracy has been demonstrated in the evaluation of chronic liver diseases, in comparison with other diagnostic modalities. Many further technical advances have been introduced in recent years. Gastroenterology training programs should include formal diagnostic laparoscopy training as part of their curriculum.

Acute iridocyclitis in a patient with AIDS diagnosed as toxoplasmosis by PCR.

PURPOSE: To study the etiology of an acute iridocyclitis in a patient with AIDS using polymerase chain reaction (PCR) analysis of aqueous humor. METHODS: Case report describing a patient diagnosed with toxoplasmic retinochoroiditis in his left eye. He stopped his treatment after three weeks and subsequently developed an acute iridocyclitis without chorioretinitis in the fellow eye. Anterior chamber paracentesis was performed and aqueous humor was assayed by PCR. RESULTS: PCR of the aqueous humor showed positivity for Toxoplasma gondii. The iridocyclitis responded to topical dexamethasone and oral treatment with pyrimethamine and sulfadiazine. CONCLUSION: PCR is an effective method to diagnose toxoplasmic iridocyclitis in a patient with AIDS.

Influence of ceramides in the solubilization of stratum corneum lipid liposomes by C(12)-betaine/sodium dodecyl sulfate mixtures.

The solubilization of liposomes modeling the stratum corneum (SC) lipid composition and those obtained varying the proportion of ceramides by means of dodecyl betaine (C(12)-Bet)/sodium dodecyl sulfate (SDS) mixtures was studied. The surfactant/lipid molar ratios (Re) and the bilayer/aqueous phase partition coefficients (K) were determined by monitoring the changes in the static light scattering of the system during solubilization. The fact that the free surfactant concentration was always similar to its critical micelle concentration (CMC) indicates that the liposome solubilization was mainly ruled by the formation of mixed micelles. The mole fraction of the zwitterionic component (X(zwitter)) of 0.4 showed the lowest ability to saturate or solubilize liposomes, although exhibiting the highest degree of partitioning into liposomes. This X(zwitter) corresponded to the highest derivation of the CMCs of these mixtures (negative synergism) and to the highest reduction in the skin irritation with respect to the anionic component. Higher and lower proportion of ceramides in the mixture led to a fall and to a rise in both the activity and the partitioning of a specific surfactant mixture (X(zwitter)=0.4). This finding could be related to the recently reported dependences of the level of ceramides in skin and function barrier abnormalities. Comparison of the present Re and K values with those reported for phosphatidylcholine (PC) liposomes shows that, although SC liposomes were more resistant to the action of surfactant mixtures, the surfactant partitioning into SC bilayers was similar to that reported for PC ones in all cases.

Influence of the level of ceramides on the permeability of stratum corneum lipid liposomes caused by a C12-betaine/sodium dodecyl sulfate mixture.

The sublytic interactions of a mixture of N-dodecyl-N, N-dimethylbetaine dodecyl betaine (C12-Bet)/sodium dodecyl sulfate (SDS) (mole fraction of the zwitterionic surfactant=0.6) with stratum corneum (SC) lipid liposomes varying the proportion of ceramides type III (Cer) were investigated. The surfactant/lipid molar ratios (Re) and the bilayer/aqueous phase partition coefficients (K) were determined by monitoring the changes in the fluorescence intensity of liposomes due to the 5(6) carboxyfluorescein (CF) released from the interior of vesicles. The fact that the free surfactant mixture concentration was always lower than its critical micelle concentration indicates that permeability changes were ruled by the action of surfactant monomers in all cases. Higher and lower Cer proportions than that of the SC lipids led to a fall and to a rise in the activity of the surfactant mixture on these bilayer structures. However, the surfactant partitioning into liposomes (or affinity with these bilayer structures) increased as the proportion of Cer increased up to the highest value was achieved for a Cer proportion similar to that in the SC lipids (about 40-45%). Thus, at low Cer proportions the ability of the surfactant mixture to alter the permeability of these bilayer structures was higher than that for liposomes approximating the SC lipid composition despite their reduced partitioning into liposomes. These findings are in agreement with the recently reported dependencies of the level of ceramides in skin lipids and function barrier abnormalities and could explain in part these dependencies.

Solubilization of phosphatidylcholine liposomes by the amphoteric surfactant dodecyl betaine.

The interaction of the amphoteric surfactant N-dodecyl-N,N-dimethylbetaine (C12-Bet) with phosphatidylcholine (PC) liposomes was investigated. Permeability alterations were detected as a change in 5(6)-carboxyfluorescein (CF) released from the interior of vesicles and bilayer solubilization as a decrease in the static light-scattering (SLS) of the system. At sublytic level a initial maximum in the bilayer/water partitioning (K) followed by an abrupt decrease of this parameter occurred as the surfactant to lipid molar ratio (Re) rose. At lytic level a direct dependence was established between both parameters. The fact that the free surfactant concentration at sublytic and lytic levels showed values lower than and similar to its critical micelle concentration indicates that permeability alterations and solubilization were determined, respectively, by the action of surfactant monomer and by the formation of mixed micelles. A direct correlation occurred in the initial interaction steps (up to 50% CF release) between the growth of vesicles their fluidity and Re. A similar direct dependence was established during solubilization (up to 30% SLS) between the fall in both the surfactant-lipid aggregate size, the SLS of the system and Re. This surfactant showed higher capacity to solubilize PC liposomes than that reported by the commonly used non-ionic surfactants octyl glucoside and Triton X-100 and by the anionic one sodium dodecyl sulfate.

Antegrade nailing for fractures of the distal femur.

Thirty-five fractures of the distal femur were treated by antegrade intramedullary nailing. All of the fractures were treated by a closed technique. In the cases in which there was extension of the fracture to the knee joint, the fracture initially was stabilized with percutaneous lag screws. Four patients died before fracture healing was complete and 11 were lost to followup. There were 14 extraarticular (Type A) and six intraarticular (Type C1 and Type C2) fractures. All of these fractures healed in a mean time of 17.27 weeks. Functional outcome using the Hospital for Special Surgery knee score was 87. Complications were infrequent with one (5%) pseudarthrosis and no infections. Although this is a very demanding technique, antegrade intramedullary nailing is an efficient procedure compared with other methods of open reduction and internal fixation for difficult distal femoral fractures.

[Paratesticular tumor. Liposarcoma of the spermatic cord]. / Tumor paratesticular. Liposarcoma del cordón espermático.

Liposarcoma of the spermatic cord is a rare tumour typically presenting in elderly people. It tends to grow around blood vessels. Most of them have a low level of malignancy and relapses tend to be localized. Metastasis, when present, occur through the haematological route, lymph spread being very unusual. Pre-operative diagnosis is infrequent and overall prognosis is good. The choice treatment is radical orchidectomy, while long-term follow-up of these patients is mandatory. When local relapses become evident, the choice treatment is extensive local excision, followed by optional adjuvant radiotherapy. Chemotherapy has not proven to be effective. This paper reviews the current literature and contributes one case of mixed liposarcoma of the spermatic cord.

[Neoplasm invasion of the renal vein by transitional cell carcinoma of the kidney pelvis]. / Invasión neoplásica de la vena renal por Ca. de células transicionales de pelvis renal.

We present two cases of renal pelvis transitional cell carcinoma with invasion of the renal vein. We emphasize the importance of preoperative diagnosis and review the diagnostic methods available for revealing this uncommon eventuality. Owing to the prognostic importance and subsequent surgical treatment, this possibility should be evaluated in those cases of renal pelvis transitional cell carcinoma with extensive parenchymatous invasion or in those cases in which kidney function cancellation occurs in the excretory urograph.

[Urologic complication during total hip replacement. Apropos of a case and review of the literature]. / Complicación urológica en el transcurso de reemplazamiento total de la cadera. A propósito de un caso y revisión de la bibliografía.

The authors present a case of vesical lesion during the recovery of a total loose hip prosthesis, without any type of endopelvic instrumentation being carried out. They show the cause of the perforation and warn against this type of complication in the above-mentioned surgery.

Reactivity of hair cystine in microemulsion media.

Synopsis Reduction of keratin cystine by thioglycolic acid incorporated in microemulsions of the water/sodium dodecilsulphate/n-pentanol/n-dodecane system has been determined. The results obtained have been interpreted in relation to the properties of the reaction media. Microemulsions with constant oil-to-surface active mixture weight ratios (R(o/s)) and different concentrations of water were chosen as reaction media. At low water concentrations a steep increase in reactivity with the increase of water was observed at all values of R(o/s). However it was more pronounced the higher the oil content. A relation between maximum cysteine formation and percolative behaviour of the microemulsion was found at high R(o/s) values.