Vesicular nanostructures composed of oleic acid and phosphatidylcholine: Effect of pH and molar ratio

Phospholipids and fatty acids are the main building blocks of biological membranes. Oleic acid is a monounsaturated omega-9 fatty acid commonly found in many natural sources. Its characteristic kinked structure grants this molecule with a great number of biological properties. To better understand the role that this kind of fatty acids play into phospholipid membranes, nanostructured systems formed with hydrogenated soy phosphatidylcholine and oleic acid were studied in this work by means of cryo-electron microscopy, dynamic light scattering and differential scanning calorimetry. Differences concerning size, morphology and phase behavior were found when those systems were prepared at different conditions of pH and molar ratio between both compounds. Broadly, it was seen how alkaline mediums and high proportions of oleic acid reduced the size of the structures and increased the fluidity of the membranes. The ease of preparation of these lipid systems, and the response to pH suggests a future use of these systems as model membranes or delivery systems.

Synthesis and antiproliferative activity of sulfa-Michael adducts and thiochromenes derived from carbohydrates

The synthesis of new carbohydrate-derived 3-nitro-2H-thiochromenes with potential antiproliferative activity is described.

Effects on soil organic matter mineralization and microbiological properties of applying compost to burned and unburned soils

This study was undertaken in the context of a project of reclamation of a burned forest area applying municipal waste compost (MWC) and it consisted of an incubation experience carried out under laboratory conditions. The objectives of this research were to asses the effect of three doses of MWC added to burned and unburned calcareous soils on a) SOM mineralization and b) soil microbiological parameters. The laboratory incubation experience was carried out with three compost doses (1, 2 and 4% w/w) on a burned soil and another unburned one from an adjacent plot, besides the corresponding control samples. The mineralization kinetics of the organic matter was studied for 92 days. The kinetics data were adjusted to a double exponential model, showing two C pools of different degrees of resistance to mineralization and concentration, with half-life times of 1.9-4.9 and 34-76 days, respectively. In the unburned soil, the initial potential mineralization rate of the labile and stable C pools showed an opposed behavior, increased and decreased with the MWC dose, respectively. However in the burned soil no significant tendencies were observed. Although applying compost tended to increase the size of more labile pool with respect to total mineralizable C, however most of the soil or compost OM did not result mineralizable in the short and medium term. The compost amendment did not increase soil microbial activity.

Optimisation of mesenchymal stromal cells karyotyping analysis: implications for clinical use

PURPOSE

The aim of this study was to optimise the yield of metaphases in mesenchymal stromal cells (MSC) in vitro cultures and to study the karyotype of MSC expanded in good manufacturing practice (GMP) conditions for clinical use.

BACKGROUND

MSC are being increasingly used in clinical trials for a number of diseases. Biosafety demonstration in all cases is mandatory. Unfortunately, current standard karyotyping methods fail to obtain enough number of evaluable metaphases.

METHODS AND MATERIALS

In the present work, to optimise the yield of metaphases in MSC expanded in vitro, we have tested several conditions by modifying colcemid concentration (we have tested 0.01, 0.05 and 0.1 µg mL(-1) ) and exposure time (during 5, 15 and 24 h). We further applied these optimised conditions to 61 MSC expansions in GMP conditions for clinical use.

RESULTS

Our results show that the highest number of metaphases was obtained when MSC were incubated with 0.05 µg mL(-1) of colcemid overnight (15 h), compared to the remaining experimental conditions. In most cases (59/61 cases) enough number of metaphases was obtained. And what is more relevant, only in one case a karyotypic abnormality was found (trisomy of chromosome 10), and cells were subsequently discarded for clinical use.

CONCLUSION

We describe here an optimal method to obtain enough number of metaphases for karyotype analysis of in vitro expanded MSCs, what is essential for their clinical use in cell therapy programmes.

Effect of cooking on the chemical composition of low-salt, low-fat Wakame/olive oil added beef patties with special reference to fatty acid content

Changes in chemical composition, with special reference to fatty acids, as affected by cooking, were studied in low-salt (0.5%)/low-fat patties (10%) with added Wakame (3%) and partial or total replacement of pork backfat with olive oil-in-water emulsion. The addition of Wakame and olive oil-in-water emulsion improved (P < 0.05) the binding properties and the cooking retention values of moisture, fat, fatty acids and ash, which were close to 100%. Partial and total replacement of animal fat with olive oil-in-water emulsion reduced (P < 0.05) saturated fatty acids (SFAs), while total replacement also reduced (P < 0.05) polyunsaturated fatty acid (PUFAs) contents. The fatty acid concentration in cooked patties was affected by product formulation. Unlike the case of all animal fat patties, when olive oil was added the cooking process increased (P < 0.05) SFAs, monounsaturated fatty acids (MUFAs) and PUFA n-3 (linolenic acid) and n-6 (linoleic acid) contents. Cooked formulated patties with seaweed and partial or total replacement of pork backfat by oil-in-water emulsion and with seaweed added were less calorie-dense and had lower SFAs levels, while samples with olive oil had higher MUFAs levels.

Liposomes as Alternative Vehicles for Sun Filter Formulations

The aim of our study was to determine the influence of several types of liposomes with a different lipid composition on the percutaneous absorption of one conventional sun filter with a lipophilic character (ethyl hexyl methoxycinnamate) using both in vitro and in vivo methodologies. Three different liposomes were prepared with unsaturated and saturated phosphatidylcholine (PC, HPC), and with a wool lipid mixture (IWL) with a composition similar to that of the stratum corneum lipids. Results showed that the liquid crystalline state associated with PC liposomes plays a key role in enhancing skin penetration. when liposomes with a composition and structural organization similar to that of the stratum corneum lipids (HPC and IWL) are used, the skin penetration is retarded, suggesting a certain reinforcement of the stratum corneum barrier. These two types of liposomes could be regarded as alternatives to conventional oil/water emulsions in the formulations of lipidic sun filters. Finally, an acceptable correlation was obtained using both in vitro and in vivo methodologies to evaluate the corresponding skin absorption profile.

Risk factors for multidrug-resistant tuberculosis in a tuberculosis unit in Madrid, Spain

The setting for this retrospective cohort study was a specialised tuberculosis unit in Madrid, Spain. The objective was to describe the risk factors for multidrug-resistant tuberculosis (MDR-TB). The medical records of all patients admitted to the unit were reviewed retrospectively to identify factors associated with multidrug resistance. Patients with positive culture for M. tuberculosis and with available drug-susceptibility tests were included. The variables assessed were age, gender, country of origin, homelessness, alcohol consumption, intravenous drug use, methadone substitution therapy, contact with a tuberculosis patient, sputum smear, site of disease, previous tuberculosis treatment, HIV infection, history of imprisonment, diabetes mellitus and chronic obstructive pulmonary disease. Thirty patients with MDR-TB and 666 patients with non-MDR-TB were included from the years 1997 to 2006. The only factors associated with MDR-TB in multivariate analysis were previous tuberculosis treatment (OR: 3.44; 95% CI: 1.58-7.50; p = 0.003), age group 45-64 years (OR: 3.24; 95% CI: 1.34-7.81; p = 0.009) and alcohol abuse (OR: 0.12; 95% CI: 0.03 to 0.55; p = 0.003). In our study, patients who had had previous treatment for tuberculosis, who were 45-64 years of age or who had no history of alcohol abuse were more likely to have MDR-TB.

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.

New arrangement of proteins and lipids in the stratum corneum cornified envelope

A new arrangement of proteins and lipids of stratum corneum (SC) cornified envelope (CE) is proposed. The chemical analysis of CE revealed the presence of free fatty acids (FFA), ceramides (Cer), and important percentages of glutamic acid/glutamine (Glx) and serine (Ser) residues. The molecular structure of these components suggests the existence of covalent links not only between Cer and Glx but also between FFA and Ser. The protein distribution of extracellular surface of CE, i.e., the proteins that could be involved in the bonds with lipids, was studied using post- and pre-embedding immunolabeling electron microscopy. Some loricrin (protein rich in Ser) was detected in the outermost part of the CE protein layer. The external arrangement of some domains of this protein may give rise to form linkages with FFA, yielding further insight into the CE arrangement in which Cer-Glx bonds and FFA-Ser bonds would be involved. Although the importance of fatty acids in the cohesion and barrier function of SC has been widely demonstrated, their role could be associated not only to the presence of these lipids in the intercellular lamellae but also in the CE, in the same way that Cer.

First 100 liver transplants at the medico-surgical research center (CIMEQ)

In July 1999 we began a liver transplant program that to October 2005 has included 100 liver transplants in 92 patients, eight retransplants, and two combined liver and kidney grafts. Twelve transplants were in pediatric patients, who showed a 92% survival rate in the first year. Fifty-four percent of the patients were male and 46% female. The most frequent etiologies of cirrhosis were 27% hepatitis virus C, 18% alcoholic, 13% cryptogenic, and 11% autoimmune. In 95% of the patients, we preserved the retrohepatic vena cava. The bile duct was reconstructed with a Kehr tube in 46% of patients with 31% using end-to-end suture with a tutor and 15% an end-to-end suture without a tutor. A hepaticojejunostomy was performed in 8%. The immunosuppression included cyclosporine (Neoral) or Prograf combined with mycophenolate mofetil or mycophenolate sodium and steroids. The most frequent biliary complications were local anastomosis leaks (6%) and stenosis (10%). The overall 1-year survival rate was 72%.

Solid mesenchymal hamartoma in an adult: a case report

Mesenchymal hamartoma of the liver (MHL) is an uncommon tumour composed of architecturally abnormal bile ducts in an uncommitted myxoid stroma. Most MHL are diagnosed in childhood and few cases have been reported in adults. This report describes a case of a well defined solid mass in the right lobe of the liver in a 51 year old man. Preoperative radiological examination revealed a large completely solid mass. Biopsy showed a dense fibrous stroma with hyalinisation and some bile ducts. A provisional diagnosis of MHL was made. Surgical excision was impossible and liver transplantation was undertaken. Definitive pathology confirmed the diagnosis. Review of published reports shows this to be the fourth case of MHL treated by liver transplantation.

Large volume peripheral blood progenitor cell (PBPC) harvest in 27 pediatric solid tumor patients weighing less than 20 Kg

9061

While PBPC collection has become a safe and common procedure in adults, fewer reports exist about its efficacy and safety in low weight pediatric patients. PBPC harvest might be difficult in this patient population and extracorporeal separator line priming with red blood cells is usually required to improve hemodynamic stability and effectiveness of the collection. We present our experience in 27 children (11 females, 16 males) weighing less than 20 kg and autografted between May 2001 and December 2005. Median age and weight at the time of apheresis were 2.7 years (0.7 to 8) and 14.3 kg (9.7 to 20), respectively. Diagnosis were neuroblastoma in 15, brain tumor in 10, and others in 2. Harvest of PBPC started after mobilization with G-CSF 10 ug/kg/day SC for 4 days. A double lumen (Arrow 7Fr) central venous catheter was surgically placed under sedation in the OR. Collections were performed using a COBE Spectra separator primed with irradiated, white cell-depleted and CMV-negative packed red cells. A median of 2 (1 to 7) procedures were performed, resulting in the harvest of 12.9 (3.6–33.1) × 108/kg mononuclear cells and 4.98 (2.33–12.69) × 106/kg CD34 (+) cells. The apheresis were performed in the presence of the parents and did not require sedation. Only 1 patient had as side-effect perioral paresthesias with normal serum calcium. No patient had vasovagal reactions. A median platelet count reduction of 66% was observed, comparing pre and post apheresis values. All patients completed the procedure with a median of 71.800 platelets (25.000 to 152.000) and a median hemoglobin of 10.8 g/dl (8.2 to13.6). All children were successfully transplanted with myeloid engraftment (ANC >500 × 109/L) at a median of 11 days (9 to 14) and independence from platelet transfusions (> 20,000x × 109/L) at a median of 17 days (8 to 39) after PBPC infusion. Median of hospitalization days was 23 (18 to 42). We conclude that PBPC harvesting using large volume continuous flow cell separation was safe, even in this low-weight pediatric population. This procedure shortens the total number of apheresis, providing an adequate number of CD34 + cells, resulting in satisfactory hematological recovery and duration of hospitalization.

No significant financial relationships to disclose.

Effect of sodium dodecyl sulfate at different hydration conditions on dioleoyl phosphatidylcholine bilayers studied by grazing incidence X-ray diffraction

The effect of the surfactant content and hydration conditions in the phases of dioleoyl phosphatidylcoline (DOPC)/sodium dodecyl sulfate (SDS) mixtures was studied. To this end, surface X-ray diffraction experiments have been performed on bilayers of the mixtures deposited on hydrophobic silicon wafers by dip coating. To investigate the effect of relative humidity (RH) on bilayer organization, a humidity chamber with dry-wet air control was used, and RH values were fixed between 1 and 65%. Our results showed, in addition to the lamellar phase, a rhombohedral phase in mixtures at low hydration conditions (RH < 30%). The d spacing between lamellae increased with the RH and SDS content. This fact could be associated with a swelling effect that is probably due to the localization of water molecules between the polar headgroups of the DOPC and SDS forming the bilayers. The electron-density profiles calculated by Fourier reconstruction of the lamellar stacking for the different samples also confirmed this fact. In addition, the increase in d spacing could be related to the increase in the hydrophilic character of the mixture when the SDS content increases. The rhombohedral phase was more clearly observed in mixtures with high SDS content. Thus, the stalk structure of the rhombohedral phase could be facilitated because of the SDS contribution to inverse structures.

Study and formation of vesicle systems with low polydispersity index by ultrasound method

The formation of liposomes with low polydispersity index by application of ultrasounds was investigated considering methodology specifications such as sonication time and sonication power. Phosphatidylcholine (PC) liposomes were formed by the evaporation-hydration method. The vesicles were sonicated using several sonication conditions. The liposomes were then characterized by dynamic light scattering (DLS) and freeze-fracture electron microscopy (FFEM). Correlation functions from DLS were treated by cumulants method and GENDIST to obtain the mean radius and polydispersity index. These calculations allowed to fix an optimal sonication time (3000 s) and a useful interval of ultrasound power between 39 and 91 W. DLS and FFEM results confirmed that vesicle size, lamellarity and the polydispersity index decreased with the increase of sonication power. Thus, we propose a systematic method to form liposomes in which the physical characteristics of the vesicles may be controlled as a function of sonication time and power.

Liver Transplantation at the Cuban Center for Medical and Surgical Research

From July 4, 1999, when a liver transplantation program was started in Cuba, to October 2003, 66 procedures had been performed in 60 patients. The most frequent reason was cirrhosis caused by hepatitis C virus (29%), and alcoholic cirrhosis (22%). Two patients received simultaneous liver-kidney transplants. Half of the patients were men. Patient ages ranged from 12 to 62 years; the average surgical time was 6 hours; and cold ischemia time was 4 to 14 hours. The average blood consumption was 2033 mL; 2900 mL of plasma and 8 units of platelets were used in 7 cases. Immunosuppression was mainly cyclosporine (Neoral), mycophenolate mofetil or azathioprine, and prednisone. Acute cellular rejections were treated in almost all cases with 3 doses of methylprednisolone. The most frequent complications were biliary (24%), hepatic arterial thrombosis (12%), post-surgical bleeding (10%), acute cellular rejection (24%), and ductopenic rejection (2%). The overall 1-year survival rate was 73.7%.

Real-time deformable models for surgery simulation: a survey

Simulating the behaviour of elastic objects in real time is one of the current objectives of computer graphics. One of its fields of application lies in virtual reality, mainly in surgery simulation systems. In computer graphics, the models used for the construction of objects with deformable behaviour are known as deformable models. These have two conflicting characteristics: interactivity and motion realism. The different deformable models developed to date have promoted only one of these (usually interactivity) to the detriment of the other (biomechanical realism). In this paper, we present a classification of the different deformable models that have been developed. We present the advantages and disadvantages of each one. Finally, we make a comparison of deformable models and perform an evaluation of the state of the art and the future of deformable models.

Influence of chemical and freezing fixation methods in the freeze-fracture of stratum corneum

A comparison between two fixation techniques for freeze-fracture was established. Stratum corneum (SC) samples from pig epidermis were fixed using high-pressure freezing (HPF) and using plunging in propane freezing; the latter after chemical fixation. Then, frozen samples were freeze-fractured, coated with platinum-carbon, and visualized using a high-resolution low-temperature scanning electron microscope and a transmission electron microscope. Our results indicate that the plane of freeze-fracture was different depending on the fixation and freezing methodology used. In the samples frozen by HPF without chemical fixation, the fracture plane laid mainly between the lipid lamellae. However, when chemical fixation and plunging in propane freezing was used, the fracture plane did not show preference to a specific way. Plunging in propane freezing of chemically fixed samples, on the other hand, provides a more homogeneous fracture behaviour. Thus, depending on the methodology used, we can favour a visualization of either lipid or protein domains of the SC. These results could be very useful in future ultrastructural studies in order to facilitate the microscopic visualization and interpretation of the complex images such as those of SC and even of other samples in which different domains coexist.

Cystic echinococcosis: analysis of the serological profile related to the risk factors in individuals without ultrasound liver changes living in an endemic area of Tacuarembó, Uruguay

Cystic echinococcosis (CE) is a high prevalence zoonosis among the rural population of Tacuarembó (Uruguay). The correlation between serological data and the incidence of risk factors was studied in a survey carried out in 1998 among rural communities where 480 individuals were examined by means of abdominal sonography (local prevalence=0·8%). Serum samples (305) were analysed by ELISA to determine specific IgG against crude antigens from Echinococcus granulosus. A total of 27 individuals exhibiting no detectable changes in abdominal sonographic examination were found to be seropositive (‘ultrasound normal group’). Of these individuals 9 were seroreactive against purified antigen B. A significant degree of correlation was found between seroreactivity and the incidence of some risk factors (CE antecedent in the family, P<0·005 and use of rural water, P<0·0001) among this group. Follow-up of individuals of the ‘ultrasound normal group’ was carried out after 2 years to evaluate the implications of this serological reactivity. No predictive value for cyst development was assessed with complementary image study; in contrast transient antibodies were observed with both crude and purified antigen as approximately 60% of individuals became negative when re-sampled.

Environmental enrichment-behavior-oxidative stress interactions in the aged rat: issues for a therapeutic approach in human aging

The effects of environment enrichment on motor activity, exploration, and cognitive performances were studied in aged rats. Both nonimpaired (NI) and impaired (I) rats were submitted to daily training in a complex-enriched environment (cEE) for 60 days. Animals were examined at spatial water maze task, passive avoidance test, open-field test, and sensorimotor coordination tasks (bridges test and Marshall scales). At the end of experiments, animals were killed for brain biochemical determinations (gluthatione content and specific-ChAT activity). Results after the first evaluation (before training) corroborate that the aged rat population showed a heterogeneity in behavioral patterns like that observed in humans. Also, cEE modified exploration activity, cognition, motor functions, and biochemical markers in both NI and I groups, but changes reached significant relevance for the last group. It is significant that neurotrophins, "novo" synthesis of neurotransmitters, and oxidative stress levels may mediate the observed changes, indicating that the aged brain still has appreciable plasticity in response to well-manipulated environmental stimulation. Finally, our results also support the novel concepts and programs in prevention/reduction both in incidence/severity and outcome of age-associated neurodegenerative conditions.

Effect of the electrostatic charge on the mechanism inducing liposome solubilization: a kinetic study by synchrotron radiation SAXS

The anionic surfactant sodium dodecyl sulfate (SDS) was used to induce the initial steps of the solubilization of liposomes. The structural transformations as well as the kinetics associated with this initial period were studied by means of time-resolved small-angle X-ray scattering (SAXS) using a synchrotron radiation source. Neutral and electrically charged (anionic and cationic) liposomes were used to investigate the effect of the electrostatic charges on the kinetics of these initial steps. The mechanism that induces the solubilization process consisted of adsorption of surfactant on the bilayers and desorption of mixed micelles from the liposomes surface to the aqueous medium. In all cases the time needed for desorption of the first mixed micelles was shorter than that for complete adsorption of the surfactant on the liposomes surface. The present work demonstrates that adsorption of the SDS molecules on negatively charged liposomes was slower and release of mixed micelles from the surface of these liposomes was faster than for neutral liposomes. In contrast, in the case of positively charged liposomes, the adsorption and release processes were, respectively, faster and slower than those for neutral vesicles.

Monoclonal antibodies against a 62 kDa proteinase of Trichomonas vaginalis decrease parasite cytoadherence to epithelial cells and confer protection in mice

Trichomonas vaginalis infects the epithelium of the genital tract. The mechanism by which it invades the tissue leading to the disease is not thoroughly understood. However, results of several studies seem to agree that parasite adhesion to epithelium cells is the initial step leading to infection in women. T. vaginalis is associated with high levels of proteolytic activity. The role of some of these proteinases in the development of infection has been demonstrated. The current study establishes the role of a 62 kDa excretion-secretion proteinase in parasite cytoadherence. Monoclonal antibodies (MAbs) against this enzyme were tested for their ability to inhibit this process. Three stable hybrid producers of IgG(1)class MAbs (4D8, 1A8, 3C11) against the 62 kDa proteinase were obtained. Two of them (4D8 and 1A8) showed parasite recognition by immunofluorescence. Parasite cytoadherence to a monolayer of HeLa cells was inhibited by the 4D8, 1A8 and 3C11 antibodies. MAb 4D8 administered 24 h before a challenge with T. vaginalis by the intraperitoneal route was able to protect the majority of mice. Nitric oxide levels in the serum of animals inoculated with MAb 4D8 and challenged with the parasite were significantly different from those recorded in mice treated with an unrelated MAb. These studies show that an appropriate antibody against 62 kDa proteinase can help the host resist a challenge by the intraperitoneal route with T. vaginalis.

Transcranial Doppler sonography in fulminant hepatic failure

The clinical course of patients with fulminant hepatic failure (FHF) is often worsened by the presence of cerebral edema and endocranial hypertension. In spite of the multiple studies using Transcranial Doppler Sonography (TCDS), few have shown the cerebral blood flow (CBF) pattern among patients with encephalopathy resulting from FHF.

OBJECTIVE

Our objective was to characterize the CBF pattern in these patients through the use of TCDS to provide therapeutic strategies.

METHOD

The TCDS pattern was assessed in five patients diagnosed with FHF and compared with a control group who displayed critical neurologic conditions not associated with FHF. Pulsatile index, systolic, diastolic, and mean velocity of the middle cerebral artery were measured.

RESULTS

The mean age of patients with FHF was 45.4 years. One hundred percent were women, with viral hepatitis as the predominant etiology. A cerebral hypoperfusion pattern was found in 80% of the FHF group and 40% of the control group. In the former group there was no evidence of hyperemia, as there was among 20% of the control group. The mean values of velocity and pulsatile index were 36.6 cm/sec and 2.4, respectively, in the FHF group and 47.8 cm/s and 1.8 in the control group (P=0.268, P=0.402).

CONCLUSIONS

FHF patients show a predominance of cerebral hypoperfusion pattern with mean velocities lower than normal values and an increased pulsatile index. We recommend that clinicians take appropriate measures to improve cerebral perfusion and avoid hypoxia. Hyperventilation as a first level measure is contraindicated.

The transplantation donation process in the Centro de Investigaciones Medico Quirurgicas of Cuba: 1999-2002

OBJECTIVE

In 1998 in the Centro de Investigaciones Medico Quirurgicas the Transplant Coordination Office (TCO) was created, with the aim to organize a system to support a hepatic transplantation program. This organization, which changed the transplantation-donation process not only in our center but in the whole country, is described in this article.

METHOD

The files of donors generated in our hospital were studied together with the transplant coordination records, from 1999 till the first half of 2002.

RESULTS

In the period studied, 21 potential donors were diagnosed with brain death, yielding a donation rate of 71.4%. Brain death was most frequently caused by vascular brain disease; however, in the realized donor group, the cranioencephalic trauma predominated. The typical donor was a man of average age 39.2 years (range, 18-86 years). Among the potential donors, 24% were excluded based on medical criteria, and 5% due to family objections. Forty liver transplantation were performed in 36 patients including 1 liver-kidney simultaneous procedure. The principal etiologies for transplant included hepatitis C virus cirrhosis, 22%; alcoholic, 19%; and acute hepatic failure, 13%. Kidney transplantations were performed in 70 patients, including 41 from cadaveric donors (53.6%) and 29 from living related donors (41.4%). In 2001, a pancreas-kidney transplantation program was started.

CONCLUSION

The creation of the TCO has been of paramount importance to optimize transplantation program functions.

Influence of the temperature in the adsorption of sodium dodecyl sulfate on phosphatidylcholine liposomes

The influence of the temperature on the adsorption of monomeric and micellar solutions of the anionic surfactant sodium dodecyl sulfate (SDS) on phosphatidylcholine (PC) liposomes was investigated using the fluorescent probe 2-(p-toluidinyl)-naphthalene-6-sodium sulfonate (TNS). The number of adsorbed molecules was quantified by measuring changes in the electrostatic potential (Psi(o)) of the liposomes/probe during an incubation with SDS at varying temperatures. At low surfactant concentrations (from 0.05 to 0.25 mM), the increase in temperature reduced the number of surfactant molecules incorporated per vesicle regardless of the incubation time, whereas at high surfactant concentrations (from 0.50 to 1.0 mM) the incubation time has an opposite effect on this process. Thus, after 10s, the surfactant adsorption decreased with temperature, yet it increased progressively with time. The adsorption was linear with temperature below critical micellar concentration (CMC) of SDS and this linear tendency did not change above CMC. This suggests an adsorption of SDS monomers regardless of the surfactant concentration.

In vitro susceptibility of Cryptococcus neoformans serotypes to GM 237354 derivative of the sordarin class

In vitro susceptibility to the sordarin derivative GM 237354 and amphotericin B were tested in a total of 190 Cryptococcus neoformans clinical isolates from different geographical areas of Spain and South American countries. Minimal inhibitory concentrations (MICs) were obtained using the NCCLS reference microbroth dilution method and analysed according the serotypes of Cr. neoformans. The MICs for amphotericin B were lower than 1.0 microg ml(-1) (MIC90% 0.5 microg ml(-1) , MIC50% 0.125 microg ml(-1)) but five isolates showed MICs of 2.0 microg ml(-1) to GM 237354 (MIC90% 1.0 microg ml(-1), MIC50% 0.5 microg ml(-1)). Cryptococcus neoformans var. gattii serotype B, was significantly less susceptible than A and AD serotypes (P = 0.047 and P = 0.022, respectively).

Assembly properties and applications of a new exopolymeric compound excreted by Pseudoalteromonas antarctica NF3

The self assembly properties and applications of an exopolymeric compound (EC) of a glycoprotein character excreted by a new gram-negative species, Pseudoalteromonas antarctica NF3, have been reviewed. This compound exhibited surface-active properties in water, with a concentration of 0.20 mg ml(-1) being the key value associated with its physicochemical properties. Unsonicated EC aqueous dispersions showed the coexistence of concentric multilamellar and small unilamellar aggregates by transmission electron microscopy (TEM). Sonication of these dispersions revealed that each lamellae of the initial multilamellar structures were made up of various subunits coiled coils. As for the ability of this exopolymeric biomaterial to coat phosphatidylcholine (PC) liposomes and to protect these vesicles against different surfactants, freeze-fracture TEM micrographs of liposome/EC aggregates revealed that the addition of the EC to liposomes led to the formation of a film (polymer adsorbed onto the bilayers) that coated very well the PC bilayers. The complete coating was already achieved at a PC:EC weight ratio of about 9:1. An increasing resistance of PC liposomes to surfactants (in particular sodium dodecyl sulfate) occurred as the proportion of EC in the system rose, although this effect was more effective at low EC proportions (PC:EC weight ratios from 9:1 to 8:2). Although a direct dependence was found between the growth of the enveloping structure and the resistance of the coated liposomes to be affected by the surfactants, the best protection occurred when this structure was a thin film of about 20-25 nm formed by nine to ten layers of about 2-3 nm.

Partitioning of SDS in liposomes coated by the exopolymer excreted by Pseudoalteromonas antarctica NF3 as a measure of vesicle protection against this surfactant

The capacity of glycoprotein (GP) excreted by Pseudoalteromonas antarctica NF3, to protect phosphatidylcholine (PC) liposomes against the action of the anionic surfactant sodium dodecyl sulfate (SDS) was studied in detail. To this end, changes in the surfactant partitioning between the lipid bilayer and the aqueous phase (partition coefficients, K) and in the effective surfactant to PC molar ratios (Re) were determined as a function of the amount of GP assembled with liposomes. The permeability of liposomes was determined by monitoring the changes in the fluorescence intensity of liposomes due to the release of the fluorescent dye 5(6)-carboxyfluorescein (CF) from the interior of vesicles to the bulk aqueous phase. Increasing GP amounts in the system resulted in the same interaction step as a rise in Re and a fall in the surfactant partitioning between the lipid bilayer and water. Hence, the higher the proportion of GP, the lower the surfactant ability to alter the permeability of liposomes and the lower its affinity with these bilayer structures. In addition, increasing GP proportions resulted in the same interaction step as a progressive increase of the free surfactant concentration (S(W)). The fact that the S(W) was always lower than the surfactant critical micelle concentration indicates that the interaction of SDS with coated liposomes was mainly ruled by the action of surfactant monomers in all cases.

Interleukin-3 receptor alpha chain (CD123) is widely expressed in hematologic malignancies

BACKGROUND AND OBJECTIVES

The hematopoietic system is controlled by growth factors (cytokines) which can influence cell survival, proliferation, differentiation and functional activation. The study of cytokine receptor expression by flow cytometry could allow us to differentiate between normal and tumoral cells.

DESIGN AND METHODS

We analyzed the expression of the interleukin-3 (IL-3) receptor a chain (CD123) in 22 normal samples and in a wide panel of hematologic malignancies using flow cytometry. We found that CD123 was expressed in the myeloid progenitor subpopulation but in contrast, normal lymphoid progenitors lacked CD123. We analyzed the CD123 expression pattern in 64 patients with acute leukemia, 45 with acute myeloid leukemia (AML) and 19 with acute lymphocytic leukemia (ALL) (13 B-cell lineage ALL and 6 T-cell lineage ALL).

RESULTS

All the AML cases except two patients with M7 and all the B-cell lineage ALL patients were CD123 positive. In contrast, all the T-cell lineage ALL cases tested were CD123 negative. We also studied the CD123 expression pattern in 122 patients with a B-cell chronic lymphoproliferative disease (B-CLPD). CD123 was positive in three situations: 1) typical cases of hairy cell leukemia showed a specific, strong CD123 expression, 2) a subgroup of atypical chronic lymphocytic leukemia with a marked CD11c expression was also CD123 positive, and finally 3) transformed B-CLPD showed the phenomenon of transition from CD123 negativity to CD123 positivity simultaneuosly with morphologic changes.

INTERPRETATION AND CONCLUSIONS

In summary, our data show high expression of IL-3 receptor a chain in hematologic malignancies. Given the high frequency of CD123 reactivity in blast cells in contrast to in normal precursors, this antigen could be applied to the study of minimal residual disease in acute leukemia. CD123 is expressed with a characteristic pattern in cases of hairy cell leukemia.

Use of a fluorescence spectroscopy technique to study the adsorption of sodium dodecylsulfonate on liposomes

The fluorescent probe 2-(p-toluidinyl)-naphthalene-6-sodium sulfonate was used to study the surface adsorption of sublytic concentrations of the anionic surfactant sodium dodecylsulfonate (C(12)-SO(3)) on phosphatidylcholine bilayers. The number of adsorbed molecules was quantified by determination of the electrostatic potential (psi(0)) of the bilayers. The abrupt decrease in the fluorescence intensity already detected 10 s after the surfactant addition and the slight fluorescence variations with time indicated that the surfactant adsorption was very fast and almost complete. For a given number of monomers adsorbed, a linear dependence between the lipid and C(12)-SO(3) concentrations was obtained, indicating a similar adsorption mechanism regardless of the surfactant concentration. Hence, a monomeric adsorption is assumed even in systems with a C(12)-SO(3) concentration above its critical micellar concentration (CMC). In addition, this linear correlation allowed us to determine the surfactant/lipid molar ratios (Re) (inversely related to the C(12)-SO(3) ability to be adsorbed on liposomes) and the bilayer/aqueous phase coefficients (K). The fact that the lowest values for Re were always reached after 10 s of incubation corroborates the rapid kinetic of the process. The decrease in the C(12)-SO(3) partitioning (K) when the number of surfactant molecules exceeded 15000 was possibly due to the electrostatic repulsion between the free and the adsorbed monomers, which could hinder the incorporation of new monomers on the charged surface of liposomes.