Enteric viruses replicate in salivary glands and infect through saliva.

Enteric viruses like norovirus, rotavirus and astrovirus have long been accepted as spreading in the population through fecal-oral transmission: viruses are shed into feces from one host and enter the oral cavity of another, bypassing salivary glands (SGs) and reaching the intestines to replicate, be shed in feces and repeat the transmission cycle1. Yet there are viruses (for example, rabies) that infect the SGs2,3, making the oral cavity one site of replication and saliva one conduit of transmission. Here we report that enteric viruses productively and persistently infect SGs, reaching titres comparable to those in the intestines. We demonstrate that enteric viruses get released into the saliva, identifying a second route of viral transmission. This is particularly significant for infected infants, whose saliva directly transmits enteric viruses to their mothers' mammary glands through backflow during suckling. This sidesteps the conventional gut-mammary axis route4 and leads to a rapid surge in maternal milk secretory IgA antibodies5,6. Lastly, we show that SG-derived spheroids7 and cell lines8 can replicate and propagate enteric viruses, generating a scalable and manageable system of production. Collectively, our research uncovers a new transmission route for enteric viruses with implications for therapeutics, diagnostics and importantly sanitation measures to prevent spread through saliva.

Neurturin-containing laminin matrices support innervated branching epithelium from adult epithelial salispheres.

Cell transplantation of autologous adult biopsies, grown ex vivo as epithelial organoids or expanded as spheroids, are proposed treatments to regenerate damaged branching organs. However, it is not clear whether transplantation of adult organoids or spheroids alone is sufficient to initiate a fetal-like program of branching morphogenesis in which coordinated branching of multiple cell types including nerves, mesenchyme and blood vessels occurs. Yet this is an essential concept for the regeneration of branching organs such as lung, pancreas, and lacrimal and salivary glands. Here, we used factors identified from fetal organogenesis to maintain and expand adult murine and human epithelial salivary gland progenitors in non-adherent spheroid cultures, called salispheres. These factors stimulated critical developmental pathways, and increased expression of epithelial progenitor markers such as Keratin5, Keratin14, FGFR2b and KIT. Moreover, physical recombination of adult salispheres in a laminin-111 extracellular matrix with fetal salivary mesenchyme, containing endothelial and neuronal cells, only induced branching morphogenesis when neurturin, a neurotrophic factor, was added to the matrix. Neurturin was essential to improve neuronal survival, axon outgrowth, innervation of the salispheres, and resulted in the formation of branching structures with a proximal-distal axis that mimicked fetal branching morphogenesis, thus recapitulating organogenesis. Epithelial progenitors were also maintained, and developmental differentiation programs were initiated, showing that the fetal microenvironment provides a template for adult epithelial progenitors to initiate branching and differentiation. Further delineation of secreted and physical cues from the fetal niche will be useful to develop novel regenerative therapies that instruct adult salispheres to resume a developmental-like program in vitro and to regenerate branching organs in vivo.

On the structure-property relationship of sound and hypomineralized enamel.

Developmental defects in dental enamel pose significant clinical challenges which have highlighted our limited understanding of the structure and properties of this tissue. In this study, we first investigated the contact-size dependence of the physical properties of sound and hypomineralized enamel, and then examined the microstructure to establish a structural basis for their differing properties. Depth-sensing indentation tests were carried out over a wide range of peak loads in a direction perpendicular to the enamel prisms. Hypomineralized enamel demonstrated stronger penetration dependence for measured hardness and elastic modulus than sound enamel. The microstructure of sound and hypomineralized enamel was observed using field emission scanning electron microscopy and transmission electron microscopy with support of a focused ion beam milling system. Images of sound enamel showed barely distinguishable sheath regions with minimal organic presence. In contrast, hypomineralized enamel showed thicker sheath structures surrounding the prisms and higher levels of organic content within both the prisms and the sheath regions. It is argued that the higher organic content within prism structure was responsible for an initial lower hardness and elastic modulus of hypomineralized enamel under low-load indentation. As the indentation depth increased, the thicker organic-rich sheath regions played a more important role in reducing the mechanical properties of the hypomineralized enamel. On the basis of Spears finite element model [Spears IR. A three-dimensional finite element model of prismatic enamel: a re-appraisal of the data on the Young's modulus of enamel. J Dental Res 1997; 76(10):1690-97], elastic moduli of sound and hypomineralized enamel were predicted, which matched experimental results.

Effect of the microencapsulation of nanoparticles on the reduction of burst release.

The initial burst release is one of the major problems in the development of controlled release formulations including drug-loaded micro- and nanoparticles, especially with low molecular weight drugs. The objective of the present work was to encapsulate, by the W/O/W emulsion, polymeric nanoparticles into polymeric microparticles by using non-water soluble polymers and appropriate organic solvents for the preparation of these composite microparticles. They were characterized in vitro (encapsulation efficiency, mean diameter and release kinetics) and compared with nanoparticles and classical microparticles prepared by the same method. Poly-epsilon-caprolactone (PCL) dissolved in methylene chloride was used to make nanoparticles, whereas ethylcellulose and Eudragit RS dissolved in ethyl acetate, a non-solvent of poly-epsilon-caprolactone, were used for the preparation of microparticles. Ibuprofen and triptorelin acetate were chosen as lipophilic and hydrophilic model drugs, respectively. High entrapment efficiencies were obtained with ibuprofen whereas lower amounts of triptorelin acetate were encapsulated, mainly with formulations prepared with poly-epsilon-caprolactone and Eudragit RS used alone or blended with ethylcellulose. The burst was significantly lower with composite microparticles and may be explained by the slower diffusion of the drugs through the double polymeric wall formed by the nanoparticle matrix followed by another diffusion step through the microparticle polymeric wall.

Response of blood leukocytes to thrombin receptor peptides.

Thrombin has receptor-mediated effects on a variety of cell types. A recently cloned platelet thrombin receptor exerts its effects by a tethered-ligand mechanism. A similar receptor was shown in at least two nonplatelet cell types, fibroblasts and endothelial cells. Thrombin has biologically important effects on leukocytes, but the type of receptor mediating the effects is not known. Therefore, we examined the responses of monocytes, neutrophils, and lymphocytes to thrombin and to an agonist specific for the platelet-type thrombin receptor. We compared the effects of a peptide (SFLLRNPNDKYEPF) corresponding to residues 42-55 of the cloned platelet thrombin receptor on calcium flux in platelets and leukocytes. The thrombin receptor peptide induced increases in intracellular calcium in platelets and monocytes that reached a maximum at 5 microM peptide. The maximal increase was similar in magnitude to the response to thrombin. Lymphocytes showed a small and variable increase in intracellular calcium in response to thrombin or the thrombin receptor agonist. The thrombin receptor peptide had no effect on neutrophil calcium concentrations. When the amino acid corresponding to Arg 46 was replaced with Ala in the synthetic peptide, the ability to increase intracellular calcium was abolished for both platelets and monocytes. The peptide instead had thrombin antagonist activity. Thus, monocytes respond to thrombin receptor peptides similarly to platelets. We conclude that human monocytes possess a thrombin receptor similar to that present on platelets. Furthermore, the residue corresponding to Arg 46 of the thrombin receptor is critical for receptor agonist activity.

Oral evaluation in rabbits of cyclosporin-loaded Eudragit RS or RL nanoparticles.

The hydrophobic cyclic undecapeptide cyclosporin A (CyA) used in the prevention of graft rejection and in the treatment of autoimmune diseases was encapsulated by nanoprecipitation within non-biodegradable polymeric nanoparticles. The effect of polymers (Eudragit RS or RL) and additives within the alcoholic phase (fatty acid esters and polyoxyethylated castor oil) on the size, zeta potential and the encapsulation efficiency of the nanoparticles was investigated. The mean diameter of the various CyA nanoparticles ranged from 170 to 310 nm. The size as well as the zeta potential increased by adding fatty acid ester and polyoxyethylated castor oil within the organic phase. No significant differences in surface potential were observed for all formulations tested. Probably due to the very low water solubility of the drug, high encapsulation efficiencies were observed in a range from 70 to 85%. The oral absorption of CyA from these polymeric nanoparticles was studied in rabbits and compared to that of Neoral capsule. Based on comparison of the area under the blood concentration-time curve values, the relative bioavailability of CyA from each nanoparticulate formulation ranged from 20 to 35%.

The antihypertensive effect of orally administered nifedipine-loaded nanoparticles in spontaneously hypertensive rats.

1. The therapeutic use of nifedipine is limited by the rapidity of the onset of its action and its short biological half-life. In order to produce a form devoid of these disadvantages we made nanoparticles of nifedipine from three different polymers, poly-epsilon-caprolactone (PCL), polylactic and glycolic acid (1:1) copolymers (PLAGA), and Eudragit RL/RS (Eudragit). Nifedipine in polyethylene glycol 400 (PEG) solution was used as a control. 2. The average diameters of the nanoparticles ranged from 0.12 to 0.21 micron; the encapsulation ratio was 82% to 88%. 3. In spontaneously hypertensive rats (SHR), the initial rapid fall in systolic arterial blood pressure following oral administration of nifedipine in PEG solution (from 193 +/- 3 to 102 +/- 2 mmHg) was not seen following administration of the same dose in Eudragit nanoparticles (from 189 +/- 2 to 156 +/- 2 mmHg); with PCL and PLAGA nanoparticles the initial fall in blood pressure was significantly reduced (nadirs PCL 124 +/- 2 and PLAGA 113 +/- 2 mmHg). Ten hours following administration, blood pressure in rats administered the nifedipine/PEG preparation had returned to normal (183 +/- 3 mmHg) whereas that of animals given nifedipine in nanoparticles (PCL 170 +/- 3, PLAGA 168 +/- 2, Eudragit 160 +/- 3 mmHg) was still significantly reduced. 4. All of the nanoparticle dosage forms decreased Cmax and increased Tmax and the mean residence time (MRT) values. Relative bioavailability was significantly increased with Eudragit nanoparticles compared to the nifedipine/PEG solution. 5. There was an inverse linear correlation between the fall in blood pressure and plasma nifedipine concentration with all preparations. 6. The nanoparticle nifedipine preparations represent sustained release forms with increased bioavailability, a less pronounced initial antihypertensive effect and a long-lasting action.

Stability study of nanoparticles of poly(epsilon-caprolactone), poly(D,L-lactide) and poly(D,L-lactide-co-glycolide).

The objective was to evaluate the stability of nanoparticles prepared with poly(epsilon-caprolactone), poly(D,L-lactide) and poly(D,L-lactide-co-glycolide) polymers and stored at different temperatures and in different media. The stability parameters studied were molecular weight and crystallinity of the polymer, nanoparticle size and pH. The results show that the stability of polymeric nanoparticles depends on (i) the type of polymers with the following increasing order of polymer stability: PLA25GA50 < PLA37.5GA25 < PLA50 = PCL, (ii) the storage temperature: PCL and PLA50 nanoparticles can be kept at 4 degrees C and RT during one year, while PLA37.5GA25 and PLA25GA50 nanoparticles have to be stored at 4 degrees C, and (iii) the storage conditions: buffering or freeze-drying nanoparticles improves stability.

The effect of fibrin polymerization inhibitors on quantitative measurements of plasma fibrinogen.

A number of reports have highlighted discrepancies between the DuPont aca and fibrometer-based methods for quantitating plasma fibrinogen levels. Although many authors have suggested that the presence of fibrin(ogen) degradation products are in some way responsible for the discrepancies, no direct test of this hypothesis has been carried out. In this report, the authors demonstrate that inhibitors of fibrin monomer polymerization have different effects on the aca and fibrometer assays of fibrinogen. Fibrin polymerization inhibitors allow short soluble fibrin polymers to assemble that can scatter light and are therefore detected by the aca method. However, these short polymers do not gel and thus are not detected by the fibrometer. Therefore, the fibrometer method gives lower fibrinogen values than the aca in the presence of fibrin polymerization inhibitors. The authors also assayed plasma from a patient whose fibrinogen did not polymerize normally and therefore was not measurable by the fibrometer assay. The dysfibrinogenemic plasma assayed by the aca method recorded normal fibrinogen levels. In conclusion, the DuPont aca fibrinogen assay is insensitive to alterations of fibrin polymerization whether from inhibitors or a defective fibrinogen molecule.

Evaluation of peroral silicone dosage forms in humans by gamma-scintigraphy.

Gastric emptying of oral silicone dosage forms was studied in humans by gamma-scintigraphy. To achieve a constant and predictable residence time in the stomach, three different formulations based on known concepts such as controlled swelling were investigated. The importance of physical parameters such as size or shape were also examined to assess the feasibility of designing a dosage form for gastric retention. Three shapes: minimatrices, extruded rods and moulded slabs were screened. To label the silicone polymer, two isotopes, used routinely in nuclear medicine departments, were selected: iodine-123 and indium-111. To select the most suitable isotope, the yield and the stability of the labelling were determined in vitro on the pharmaceutical dosage forms. The residence time of these silicone formulations, labelled with iodine and administered in hard gelatine capsules, was monitored in 12 subjects with a gamma camera. The study was performed under fed conditions after ingestion of a standardised meal labelled with indium. The minimatrices provided at least 3 h retention, slabs exhibited 4 h 40 min retention. For the rods the mean residence time in the stomach was around 4 h 20 min. In addition, a correlation was established between the gastric emptying of rods and the half-gastric residence time of meal. On the contrary, such a correlation was not observed for the slabs.

The preparation and evaluation of poly(epsilon-caprolactone) microparticles containing both a lipophilic and a hydrophilic drug.

An original dosage form for oral delivery based on the encapsulation of both, lipophilic and hydrophilic drugs, in poly(epsilon-caprolactone) (PCL) microparticles prepared either by the oil-in-water (o/w) or the water-in-oil-in-water (w/o/w) solvent evaporation method was developed. Microparticles were characterized in terms of morphology, size, encapsulation efficiency and drug release. The physical state of the drugs and the polymer was determined by scanning electron microscopy (SEM), X-ray powder diffractometry, and differential scanning calorimetry (DSC). Nifedipine (calcium antagonist) and propranolol HCl (beta-blocker), used for the treatment of hypertension, were chosen as lipophilic and hydrophilic drugs. The microparticles were spherical with diameters in the range of 191-351 microm by the o/w-method, and in the range of 302-477 microm by the w/o/w-method. The encapsulation efficiency (EE) was 91% for nifedipine and 37% for propranolol HCl with the o/w-method, and 83% for nifedipine and 57% for propranolol HCl with the w/o/w-method. DSC and X-ray diffraction studies showed that PCL maintained its semi-crystalline structure, while the drugs were either dispersed or dissolved in the polymer. In vitro release studies revealed a controlled release of nifedipine and propranolol HCl from microparticles prepared by the o/w-method; a burst release of propranolol HCl was observed from microparticles prepared by the w/o/w-method. In conclusion, microparticles containing both a hydrophilic and a lipophilic drug were successfully prepared.

A multi-station dental plaque microcosm (artificial mouth) for the study of plaque growth, metabolism, pH, and mineralization.

A plaque growth chamber was developed for long-term growth of five separate plaques from the same plaque or saliva sample under identical conditions of temperature and gas phase. Reagent addition and growth conditions for each plaque could be independently controlled, and each was accessible for sequential sampling and electrode insertion. Plaques were cultured for over six weeks on pellicle-coated Lux (TM) 25-mm diameter cover-slips at 35 degrees C under 5% CO2 in N2, and supplied with a medium containing 0.25% mucin (BMM) at 3.6 mL/h, and with periodic 5% sucrose. Electron microscopy and flora analysis of microcosm plaques showed that they had close similarities to reported characteristics of natural dental plaques. Diverse motile bacteria were present. Sucrose-induced Stephan pH curves and urea-induced pH rises were also similar to those reported for natural plaques. Changes in plaque urease, calcium, phosphate concentrations, and the flora were followed over five weeks in a plaque supplied with BMM containing additional 2.5 mmol/L calcium and 7.5 mmol/L phosphate. Despite this high environmental calcium phosphate concentration, there was no continuing increase in calcium levels, although plaque phosphate doubled. Urease levels fluctuated. Changes in the cultivable flora were minor. A urea-containing calcium phosphate/mono-fluorophosphate pH 5 solution, applied for six min every two h for seven days, increased plaque calcium, phosphate, and fluoride to high levels. Thus, plaques grown over several weeks in the multi-station artificial mouth exhibited metabolic and pH behavior typical of natural plaques, could be analyzed during development, and the system allowed manipulation of environmental variables important in plaque pH control and calcification.

Acute effects of ski waxing on pulmonary function.

The objective of this study was to determine whether pulmonary function is acutely affected by moderate exposure to ski waxing. Ten healthy nonsmoking young adult volunteers were exposed to 45 min of ski waxing in a small unventilated room. The exposure occurred in pairs with one individual performing the waxing while the other overlooked the waxing process. During the period of waxing, two pairs of cross-country skis were waxed with a paraffin wax and then scraped and brushed, and two pairs of cross-country skis were waxed with a fluorinated wax and then brushed. Spirometry and single-breath carbon monoxide lung diffusion capacity (DLCO) were measured immediately before and after exposure to ski waxing, and again 5-6 h after waxing. A subset of five subjects repeated the measurements on a separate day without receiving exposure to ski waxing. Data were analyzed with repeated measures ANOVA. Exposure to ski waxing induced no significant changes in spirometry and DLCO measurements. We conclude that moderate exposure to ski waxing has no significant acute effect on lung function.

Preparation and characterization of nanoparticles containing an antihypertensive agent.

Isradipine, an antihypertensive agent, was encapsulated by the nanoprecipitation method using polymers including poly(epsilon-caprolactone), poly(D,L-lactide) and poly(d, L-lactide-co-glycolide). In vitro scanning electron microscopy and differential scanning calorimetry were used to characterize the nanoparticles. The average diameters of the nanoparticles ranged from 110 nm to 208 nm. PCL nanoparticles were larger than nanoparticles prepared with the other polymers. The zeta potential of the nanoparticles was negative, with values of about -25 mV which promoted good stabilization of the particles. The amorphous state of PLA and PLAGA non-loaded nanoparticles and the semi-crystalline state of PCL were demonstrated with X-ray diffraction and differential scanning calorimetry. For all nanoparticles, isradipine was found to be totally amorphous in the polymer which suggested that the drug was molecularly dispersed in the matrix. The colloidal suspensions displayed a sustained release profile in comparison with the drug release profile of isradipine in a PEG solution. Results from this investigation suggest that these nanospheres will be a good candidate delivery system for oral administration, to reduce the initial hypotensive peak and to prolong the antihypertensive effect of the drug.

Transmission of a procoagulant signal from tissue factor-bearing cell to platelets.

The goal of the current study was to examine the mechanism by which factor VIIa/tissue factor (TF) activity leads to platelet activation as the first step in initiation of coagulation. Adherent, endotoxin-treated monocytes were used as a cellular source of TF. The processes that led to platelet activation were rapid, since incubation of coagulation factors and platelets with TF for as little as 15 s initiated platelet activation. Further, direct contact between the TF source and platelets was not required since incubation of plasma levels of coagulation zymogens and inhibitors with TF generated the initiating signal for platelet activation. We hypothesized that thrombin generation on the cells that contained TF was the initiating signal for platelet activation. To test this hypothesis, factor VIIa, inhibitors, and different combinations of coagulation zymogens were incubated with TF-bearing cells. The supernatants were then transferred to a suspension of unactivated platelets with plasma concentrations of zymogen factors and inhibitors. Platelet activation was much more efficient when all the elements of the IIase complex (factors II, V and X) were preincubated with factor VIIa/TF than when only factor X was incubated with factor VIIa/TF. Finally, TF was incorporated into lipid vesicles containing phosphatidyl choline either with or without phosphatidyl serine. Vesicles without phosphatidyl serine have no IIase activity. Platelets were incubated with TF, coagulation zymogens and inhibitors. Platelet activation only occurred when the lipid vesicles could support IIase activity. We conclude that sufficient thrombin generation occurs on the TF-bearing cell (or TF-bearing vesicle) in the absence of platelets, to provide the procoagulant signal that leads to platelet activation. The activated platelet surface then provides sites for TF-activated factor IXa to recruit factor Xa to bind and assemble into functional Xase and IIase complexes.

Comparison of the biodistribution in mice of 111indium oxine encapsulated into poly(lactic-co-glycolic)-D,L-85/15 and poly(epsilon caprolactone) nanocapsules.

Poly(lactic-co-glycolic)-D,L-85/15 (PLAGA) nanocapsules and poly(epsilon caprolactone) (PCL) nanocapsules were labeled with a relatively long half-life compound that is usually used in humans; that is, 111In-labelled oxine (111In oxine). This labeling technique led to a high 111In oxine entrapment efficiency and good stability during dialysis against phosphate buffer and phosphate buffered albumin solution. Because of these characteristics, the nanocapsules biodistribution was followed up after intravenous administration for up to 96 h by determining the gamma activity in the tissues after sampling. The administration of the PCL-encapsulated 111In oxine led to a decrease in the blood radioactivity and an increase in the liver radioactivity compared with the solution. This effect was even more pronounced with the PLAGA nanocapsules. Finally, the activity level in other tissues, such as the kidneys, the lungs, and the spleen, appeared to be rather low and only slightly affected by the encapsulation into one or the other polymer.

Studies on platelets: XXVIII: acute thrombocytopenic purpura due to lidocaine (Xylocaine)-mediated antibody. Report of a case.

A patient developed severe thrombocytopenia three days after the administration of lidocaine (Xylocaine) for dental extractions. Petechial bleeding and thrombocytopenia regressed promptly, probably aided by treatment with adrenocorticotropic hormone (ACTH) and prednisone. The patient is well one year after her experience and has received other drugs with impunity. The thrombocytopenia appeared related to the presence of a specific antibody, predominantly immunoglobulin M (IgM), heat labile, in the patient's plasma and serum. The antibody was lytic in action and needed complement. It probably coupled to the drug, forming an antigen-antibody complex able to fix itself to and cause the lysis of platelets. Thrombocytopenia was induced with the parenteral administration of a small dose of lidocaine to the patient. This case may represent the first recorded example of hematologic complication related to the use of lidocaine.

The influence of morphological variation on Candida albicans adhesion to denture acrylic in vitro.

Using denture acrylic pieces coated with either whole human stimulated saliva or oral streptococci, the binding ability of three different Candida albicans strains was investigated. The C. albicans strains include a clinical isolate with the commonly observed, smooth, round colonial morphology (strain 613p), a morphological variant spontaneously derived from the clinical isolate strain 613p (strain 613m1BK) and a clinical isolate from an oral lesion that was also a morphological variant upon primary isolation (strain 228). Levels of adhesion to the acrylic pieces were determined radiometrically using C. albicans cells metabolically labelled with [35S]-methionine. Whole stimulated saliva significantly increased the binding of all strains compared to uncoated acrylic. However, the level of binding of strain 613p to saliva-coated acrylic was significantly greater than the levels observed for the morphological variant strain 613m1BK. Coating acrylic pieces with either Streptococcus sanguis NCTC 10904, Strep. mutans GS-5 or Strep. sobrinus ATCC 27352 instead of saliva resulted in significantly greater binding by strain 613p compared to uncoated acrylic. Pre-coating the acrylic with the oral streptococci did not significantly increase the binding of morphological variant strains 613m1BK and 228 compared to uncoated acrylic. In general, preincubation of adherent streptococci with sucrose to induce the synthesis of extracellular carbohydrate polymers did not significantly increase the binding levels of the C. albicans strains above those observed using streptococci in buffer alone. Compared to its parental strain 613p, morphological variant strain 613m1BK adhered poorly to denture acrylic coated with either salivary constituents or oral streptococci, while strain 228 adhered to the same substrates at an intermediate level. Furthermore, physical disaggregation of clusters of the morphological variant strain 613m1BK did not appear to increase its binding capacity to saliva-coated denture acrylic. The effect of whole stimulated saliva on the adherence of C. albicans 613p to a variety of plastic substrates in addition to denture acrylic was examined. Overall, saliva pre-coating of the various plastics promoted C. albicans 613p adhesion. The adhesion of strain 613p to denture acrylic coated with whole stimulated saliva from each of five different donors or with parotid and submandibular/sublingual saliva from each of two donors was also examined. Regardless of donor, a coating of whole stimulated saliva significantly increased the binding of strain 613p to denture acrylic compared to uncoated acrylic. In addition, a coating of parotid saliva significantly increased the binding of strain 613p to denture acrylic compared to submandibular/sublingual saliva.

Influences of process parameters on nanoparticle preparation performed by a double emulsion pressure homogenization technique.

The preparation of nanoparticles (NP) as an improved colloidal carrier system for proteins was investigated. Bovine serum albumin (BSA) was used as model drug. Owing to the high solubility of the protein in water, the double emulsion technique has been chosen as one of the most appropriate method. In order to both reaching submicron size as well as increasing the grade of monodispersity compared to previous preparation techniques, a microfluidizer as homogenization device was used. All experiments were performed using two biodegradable polymers, poly[D,L-lactic-co-glycolic acid] 50/50 (PLGA) and poly[epsilon-caprolactone] (PCL). The homogenization procedure has been optimized with regard to particle size and monodispersity by studying the influence of the homogenization time as well as the amount of polymer and surfactant in the external aqueous phase. The drug loading has been improved by varying the concentration of the protein in the inner aqueous phase. By increasing the protein concentration in the inner aqueous phase the polydispersity was slightly higher, while the particle size was not influenced significantly. The BSA encapsulation efficiency decreased with higher protein concentration in the inner aqueous phase. All release profiles were characterized by a initial burst effect, a higher release rate was obtained after 4 weeks for PLGA NP (60%) compared with PCL NP (47%).

Biodegradable monodispersed nanoparticles prepared by pressure homogenization-emulsification.

The aim of the present work was to investigate the preparation of nanoparticles (NP) as potential drug carriers for proteins. The hydrophilic protein bovine serum albumin (BSA) was chosen as the model drug to be incorporated within NP. Owing to the high solubility of the protein in water, the double emulsion technique has been chosen as one of the most appropriate method. In order to reach submicron size we used a microfluidizer as a homogenization device with a view to obtaining NP with a very high grade of monodispersity. Two different biodegradable polymers, poly[D, L-lactic-co-glycolic acid] 50/50 (PLGA) and poly[epsilon-caprolactone] (PCL) has been used for the preparation of the NP. The drug loading has been optimized by varying the concentration of the protein in the inner aqueous phase, the polymer in the organic phase, the surfactant in the external aqueous phase, as well as the volume of the external aqueous phase. The BSA encapsulation efficiency was high (>80%) and release profiles were characterized by a substantial initial burst release for both PLGA and PCL NP. A higher release was obtained at the end of the dissolution study for PLGA NP (92%) compared with PCL NP (72%).