Beyond traditional therapy: Mucoadhesive polymers as a new frontier in oral cancer management

In recent times mucoadhesive drug delivery systems are gaining popularity in oral cancer. It is a malignancy with high global prevalence. Despite significant advances in cancer therapeutics, improving the prognosis of late-stage oral cancer remains challenging. Targeted therapy using mucoadhesive polymers can improve oral cancer patients' overall outcome by offering enhanced oral mucosa bioavailability, better drug distribution and tissue targeting, and minimizing systemic side effects. Mucoadhesive polymers can also be delivered via different formulations such as tablets, films, patches, gels, and nanoparticles. These polymers can deliver an array of medicines, making them an adaptable drug delivery approach. Drug delivery techniques based on these mucoadhesive polymers are gaining traction and have immense potential as a prospective treatment for late-stage oral cancer. This review examines leading research in mucoadhesive polymers and discusses their potential applications in treating oral cancer.     

Design and Development of Gliclazide Mucoadhesive Microcapsules: In Vitro and In Vivo Evaluation

In this study an attempt was made to prepare mucoadhesive microcapsules of gliclazide using various mucoadhesive polymers designed for oral controlled release. Gliclazide microcapsules were prepared using sodium alginate and mucoadhesive polymer such as sodium carboxymethyl cellulose (sodium CMC), carbopol 934P or hydroxy propylmethyl cellulose (HPMC) by orifice-ionic gelation method. The microcapsules were evaluated for surface morphology and particle shape by scanning electron microscope. Microcapsules were also evaluated for their microencapsulation efficiency, in vitro wash-off mucoadhesion test, in vitro drug release and in vivo study. The microcapsules were discrete, spherical and free flowing. The microencapsulation efficiency was in the range of 65–80% and microcapsules exhibited good mucoadhesive property in the in vitro wash off test. The percentage of microcapsules adhering to tissue at pH 7.4 after 6 h varied from 12–32%, whereas the percentage of microcapsules adhering to tissue at pH 1.2 after 6 h varied from 35–68%. The drug release was also found to be slow and extended for more than 16 h. In vivo testing of the mucoadhesive microcapsules in diabetic albino rats demonstrated significant antidiabetic effect of gliclazide. The hypoglycemic effect obtained by mucoadhesive microcapsules was for more than 16 h whereas gliclazide produced an antidiabetic effect for only 10 h suggesting that mucoadhesive microcapsules are a valuable system for the long term delivery of gliclazide.     

The effect of human serum albumin on the extended storage of human oral keratinocyte viability under mild hypothermia

Isolated oral keratinocytes in suspension provide a number of advantages for use in maxillofacial surgery, however, the poor stability of this cell preparation at physiological temperatures is an apparent barrier preventing their use. The purpose of the present study was to evaluate whether human serum albumin (HSA) could serve as an effective constituent of a storage medium to enhance human oral keratinocyte (HOK) viability under conditions of mild hypothermia. Primary human oral keratinocytes were isolated from small pieces of the non-inflamed gingival tissues obtained during the extraction of the third molars of patients. HOK were cultured on collagen type I-coated culture dishes in keratinocyte growth medium (KGM). After the trypsinization of a culture dish (passage 2 or 3), freshly isolated HOK were stored for 24, 48, and 72 h at 4 degrees C or at room temperature in KGM, saline, Dulbecco's modified Eagle's medium (DMEM), saline supplemented with 10% HSA or DMEM supplemented with 10% (v/v) HSA under one atmosphere pressure. After storage, HOK cell survival was determined by dye exclusion using trypan blue and colony-forming assay and cell cycle change was obtained by flow cytometry. Highest cell viability was obtained in saline supplemented with 10% HSA and DMEM supplemented with 10% (v/v) HSA at 4 degrees C and at room temperature. Under these conditions no significant decline in keratinocyte viability was observed for at least 48 h. The cell cycle profiles of these cells were also maintained for at least 48 h at room temperature. These observations demonstrate that HSA might be better at preserving the viability of HOK stored under hypothermic and mild hypothermic conditions up to 48 h.     

Rat lung decellularization using chemical detergents for lung tissue engineering

Although pulmonary diseases account for a large number of deaths in the world, most have no treatment other than transplantation. New therapeutic methods for lung treatment include lung tissue engineering and regenerative medicine. Lung decellularization has been used to produce an appropriate scaffold for recellularization and implantation. We investigated 3-[(3-cholamidopropyl) dimethylammonio]-1-propanesulfonate (CHAPS) with sodium dodecyl sulfate (SDS) and Triton X-100 detergents for effecting rat lung decellularization. We evaluated using conventional histology, immunofluorescence staining and SEM methods for removing nuclear material while leaving intact extracellular matrix proteins and three-dimensional architecture. We investigated different concentrations of CHAPS, SDS and Triton X-100 for different periods. We found that 2 mM CHAPS + 0/1% SDS for 48 h was the best among the treatments investigated. Our method can be used to produce an appropriate scaffold for recellularization by stem cells and for investigations ex vivo and in vivo.     

Cryopreserved CD90+ cells obtained from mobilized peripheral blood in sheep: a new source of mesenchymal stem cells for preclinical applications

Mobilized peripheral blood (MPB) bone marrow cells possess the potential to differentiate into a variety of mesenchymal tissue types and offer a source of easy access for obtaining stem cells for the development of experimental models with applications in tissue engineering. In the present work, we aimed to isolate by magnetic activated cell sorting CD90+ cells from MPB by means of the administration of Granulocyte-Colony Stimulating Factor and to evaluate cell proliferation capacity, after thawing of the in vitro culture of this population of mesenchymal stem cells (MSCs) in sheep. We obtained a median of 8.2 ± 0.6 million of CD90+ cells from the 20-mL MPB sample. After thawing, at day 15 under in vitro culture, the mean CD90+ cells determined by flow cytometry was 92.92 ± 1.29 % and cell duplication time determined by crystal violet staining was 47.59 h. This study describes for the first time the isolation, characterization, and post-in vitro culture thawing of CD90+ MSCs from mobilized peripheral blood in sheep. This population can be considered as a source of MSCs for experimental models in tissue engineering research.     

Advantages of firefly luciferase as a reporter gene: application to the interleukin-2 gene promoter

The chloramphenicol acetyltransferase (CAT) gene is widely used in recombinant constructs employed to study promoter and enhancer control of gene expression. However, CAT-based assays require a laborious, multi-step procedure for quantitation of promoter activity. We have applied the recently described firefly luciferase (LUC) reporter gene to the study of the interleukin-2 (IL2) promoter and have further defined the properties of this reporter gene system. We find that IL2-LUC constructs have multiple advantages over IL2-CAT constructs. The LUC assay is highly sensitive and requires 1/10 the cells used in the CAT system. A final quantitative measure of promoter activity can be obtained within 25 h following transfection with IL2-LUC, compared to 108-160 h with IL2-CAT. Light emission significantly (fourfold) above background is detectable 3 h after induction in a direct assay of extracts from transfected cells. We have described the variability of the assay, the minimum number of transfected cells required to detect light, the stability of luciferase in cell extracts, the effect of Triton X-100 on the assay, and a rapid cell lysis procedure. The luciferase system is a simple, rapid, and sensitive method for the study of promoter activity in transfected cells, particularly for weakly expressed genes such as IL2 which give low activity in the CAT assay.     

A cytoskeleton-associated plasma membrane heparan sulfate proteoglycan in Schwann cells

Schwann cells cocultured with sensory neurons in a serum-free medium accumulate a single species of radiolabeled heparan sulfate proteoglycan (HS-PG) during incubation in medium containing 35SO4. This HS-PG was poorly extracted from cultures by solutions containing 1% Triton X-100 in low salt buffer or by solutions containing 1 M KCl, 4 M urea plus dithiothreitol, 1 mM Tris-HCl, 5 mM EDTA, or 100 micrograms/ml of heparin. The HS-PG was efficiently extracted, however, by 1% Triton X-100 in the presence of 1 M KCl or by 1% deoxycholate. These treatments solubilize both cell membranes and the Schwann cell cytoskeleton. In intact cells the HS-PG was digested by trypsin, indicating it was at least partially exposed on the cell surface. When solubilized HS-PG was applied to a column of octyl-sepharose CL-4B, more than 90% was retained by the column, but was quantitatively eluted by a solution containing 1% Triton X-100. In addition, the solubilized HS-PG could be incorporated into artificial phospholipid vesicles. These results indicate the HS-PG is an integral plasma membrane protein. The inability of low ionic strength solutions containing Triton X-100 to solubilize the HS-PG suggested it was bound to an additional structure. To determine whether the HS-PG was associated with the cytoskeleton we isolated cytoskeletons by detergent lysis of cells and centrifugation. The major protein components of isolated cytoskeletons were spectrin (Mr 225,000), vimentin (Mr 58,000), and actin (Mr 45,000). When 35SO4-labeled cells were used to prepare cytoskeletons approximately 80% of the total HS-PG was recovered in the cytoskeleton fraction. These results suggest the HS-PG is an externally exposed integral plasma membrane protein that is anchored to the Schwann cell cytoskeleton.     

Mucoadhesive bilayered tablets for buccal sustained release of flurbiprofen

The aim of this work was the design of sustained-release mucoadhesive bilayered tablets, using mixtures of mucoadhesive polymers and an inorganic matrix (hydrotalcite), for the topical administration of flurbiprofen in the oral cavity. The first layer, responsible for the tablet retention on the mucosa, was prepared by compression of a cellulose derivative and polyacrylic derivative blend. The second layer, responsible for buccal drug delivery, was obtained by compression of a mixture of the same (first layer) mucoadhesive polymers and hydrotalcite containing flurbiprofen. Nonmedicated tablets were evaluated in terms of swelling, mucosal adhesion, and organoleptic characteristics; in vitro and in vivo release studies of flurbiprofen-loaded tablets were performed as well. The best results were obtained from the tablets containing 20 mg of flurbiprofen, which allowed a good anti-inflammatory sustained release in the buccal cavity for 12 hours, ensuring efficacious salivary concentrations, and led to no irritation. This mucoadhesive formulation offers many advantages over buccal lozenges because it allows for reduction in daily administrations and daily drug dosage and is suitable for the treatment of irritation, pain, and discomfort associated with gingivitis, sore throats, laryngopharyngitis, cold, and periodontal surgery. Moreover, it adheres well to the gum and is simple to apply, which means that patient compliance is improved. Published: July 13, 2007     

Mucoadhesive bilayer tablets of propranolol hydrochloride

The purpose of this research was to study mucoadhesive bilayer buccal tablets of propranolol hydrochloride using the bioadhesive polymers sodium alginate (Na-alginate) and Carbopol 934P (CP) along with ethyl cellulose as an impermeable backing layer. The tablets were evaluated for weight variation, thickness, hardness, friability, surface pH, mucoadhesive strength, swelling index, in vitro drug release, ex vivo drug permeation, ex vivo mucoadhesion, and in vivo pharmacodynamics in rabbits. Tablets containing Na-alginate and CP in the ratio of 5∶1 (F2) had the maximum percentage of in vitro drug release without disinte-gration in 12 hours. The swelling index was proportional to Na-alginate content and inversely proportional to CP content. The surface pH of all tablets was found to be satis-factory (7.0±1.5), close to neutral pH; hence, buccal cavity irritation should not occur with these tablets. The mechanism of drug release was found to be non-Fickian diffusion and followed zero-order kinetics. The formulation F4 was optimized based on good biodhesive strength (28.9±0.99 g) and sustained in vitro drug permeation (68.65%±3.69% for 12 hours). The behavior of formulation F4 was examined in human saliva, and both the drug and the buccal tablet were found to be stable. The formulation F4 was applied to rabbit oral mucosa for in vivo studies. The formulation inhibited isoprenaline-induced tachycardia. The studies conducted in rabbits confirmed the sustained release as compared with intravenous administration. Published: September 21, 2007     

Use of resistant mutants to study the interaction of triton X-100 with Staphylococcus aureus.

Staphylococcus aureus mutants resistant to the nonionic detergent Triton X-100, isolated from the wild-type strain H and the autolysin-deficient strain RUS3, could grow and divide in broth containing 5% (vol/vol) Triton X-100, while growth of the parental strains was markedly inhibited above the critical micellar concentration (0.02%) of the detergent. Growth-inhibitory concentrations of Triton X-100 killed wild-type cells without demonstrable cellular lysis. Triton X-100 stimulated autolysin activity of S. aureus cells under nongrowing conditions, and this lytic response was markedly reduced in energy-poisoned cells. In contrast, the detergent had no effect on the activity of autolysins in cell-free systems, and growth in the presence of Triton X-100 did not alter either the cellular autolysin activity or the susceptibility of cell walls to exogenous lytic enzymes. Treatment with either Triton X-100 or penicillin G in the growth medium stimulated release of predominantly acylated intracellular lipoteichoic acid and sensitized staphylococci to Triton X-100-induced autolysis. There was no significant difference in the cell wall and membrane compositions or Triton X-100 binding between the parental strains and the resistant mutants. The resistant mutant TXR1, derived from S. aureus H, had a higher level of L-alpha-glycerophosphate dehydrogenase activity, and its oxygen uptake was more resistant to inhibition by a submicellar concentration (0.008%) of Triton X-100. Growth in the presence of subinhibitory concentrations of Triton X-100 rendered S. aureus H cells phenotypically resistant to the detergent and greatly stimulated the level of oxygen uptake. Membranes isolated from such cells exhibited enhanced activity of the respiratory enzymes succinic dehydrogenase and L-alpha-glycerophosphate dehydrogenase.     

T cell receptor can be recruited to a subset of plasma membrane rafts,independently of cell signaling and attendantly to raft clustering

The constitutive/inducible association of the T cell receptor (TCR) with isolated detergent-resistant, lipid raft-derived membranes has been studied in Jurkat T lymphocytes. Membranes resistant to 1% Triton X-100 contained virtually no CD3epsilon, part of the TCR complex, irrespective of cell stimulation. On the other hand, membranes resistant either to a lower Triton X-100 concentration (i.e. 0.2%) or to the less hydrophobic detergent Brij 58 (1%) contained (i) a low CD3epsilon amount (approximate 2.7% of total) in resting cells and (ii) a several times higher amount of the TCR component, after T cell stimulation with either antigen-presenting cells or with phytohemagglutinin. It appeared that CD3/TCR was constitutively associated with and recruited to a raft-derived membrane subset because (i) all three membrane preparations contained a similar amount of the raft marker tyrosine kinase Lck but no detectable amounts of the conventional membrane markers, CD45 phosphatase and transferrin receptor; (ii) a larger amount of particulate membranes were resistant to solubilization with 0.2% Triton X-100 and Brij 58 than to solubilization with 1% Triton X-100; and (iii) higher cholesterol levels were present in membranes resistant to either the lower Triton X-100 concentration or to Brij 58, as compared with those resistant to 1% Triton X-100. The recruitment of CD3 to the raft-derived membrane subset appeared (i) to occur independently of cell signaling events, such as protein-tyrosine phosphorylation and Ca(2+) mobilization/influx, and (ii) to be associated with clustering of plasma membrane rafts induced by multiple cross-linking of either TCR or the raft component, ganglioside GM(1). We suggest that during T cell stimulation a lateral reorganization of rafts into polarized larger domains can determine the recruitment of TCR into these domains, which favors a polarization of the signaling cascade.     

Acid Sphingomyelinase of Human Brain: Purification to Homogeneity

Abstract: Acid sphingomyelinase (sphingomyelin phosphodiesterase, EC 3.1.4.12) was purified from human brain by extraction with 0.1% Triton X-100, followed by sequential chromatography on Concanavalin A-Sepharose, octyl-Sepharose, hydroxylapatite, DEAE-cellulose, red A-agarose, Sephadex G-200, and DEAE-cellulose with ampholyte elution. Sphingomyelinase activity was purified more than 20,000-fold from the starting homogenate with a 1% yield. Specific activity of up to 800 μmol/h/mg protein could be achieved. Gel electrophoresis with 6% polyacrylamide containing sodium dodecyl sulfate gave a single protein band with a molecular weight of 70,000, in good agreement with the molecular weight previously estimated from sucrose density gradient centrifugation in 0.1% Triton X-100. Triton X-100 could be readily removed from the enzyme by sucrose density gradient centrifugation. The Triton-free enzyme showed the same K _m and pH optimum. Heat stability of the enzyme was reversibly affected by Triton X-100, in that removal of the detergent made the enzyme more heat labile. The K _m of purified enzyme for sphingomyelin was 36 μ M . It was unaffected by sulfhydryl reagents, but was inhibited by dithiothreitol at high concentrations. The preparation was free of all lysosomal hydrolase activities tested, including galactosylceramidase and α-mannosidase, which tended to copurify in our previous procedure. The enzyme was inactive toward sphingosylphosphorylcholine. It was active with bis[ p -nitrophenyll- and bis[4-methylumbelliferyl]phosphate and the chromogenic and fluorogenic sphingomyelin analogues.     

Relative Bioavailability of Chlorothiazide from Mucoadhesive Compacts in Pigs

The relative bioavailability of chlorothiazide from mucoadhesive polymeric compacts is compared to commercial oral suspension in pigs. A single-dose randomized study was conducted in 12 healthy pigs that are 9–10 weeks old. After overnight fasting, pigs were divided into two groups of six animals. To the first group, a reference product containing 50 mg of chlorothiazide suspension, and in the second group, test product (mucoadhesive compacts) chlorothiazide (50 mg) was administered with 75 mL of water via gastric tubes. Blood samples were collected between 0 to 24 h using catheters inserted into the jugular vein. Plasma was separated by protein precipitation, and chlorothiazide concentrations were determined using a high-performance liquid chromatography method. The mean T_max and the C_max of chlorothiazide following the administration of oral suspension and mucoadhesive compacts were 0.58 ± 0.20 h and 682.97 ± 415.69 ng/mL and 2.17 ± 0.98 h and 99.42 ± 124.08 ng/mL, respectively. The K_el and T_1/2 of chlorothiazide were found to be 1.06 ± 0.28 h⁻¹ and 0.70 ± 0.21 h from suspension and 0.95 ± 1.11 h⁻¹ and 2.05 ± 1.90 h from the compacts, respectively. The T_max of mucoadhesive compacts were significantly longer (p < 0.05; 2.17 h) than the reference products (0.58 h), whereas the C_max of compacts were significantly lower (99 ng/mL) than the reference product (683 ng/mL; p < 0.05). The area under the curve (AUC) of compacts accounts only 50.15% (404.32 ± 449.93 ng h/mL) of the reference product’s AUC (806.27 ± 395.97 ng h/mL). The relative bioavailability of the compacts was lower than that of the suspension, and this may be due to the narrow window of absorption for chlorothiazide.Key words: bioavailability, chlorothiazide, mucoadhesive compacts, pigs     

Mucoadhesive Bilayered Patches for Administration of Sumatriptan Succinate

The purpose of this study was to develop and optimize formulations of mucoadhesive bilayered buccal patches of sumatriptan succinate using chitosan as the base matrix. The patches were prepared by the solvent casting method. Gelatin and polyvinyl pyrrolidone (PVP) K30 were incorporated into the patches, to improve the film properties of the patches. The patches were found to be smooth in appearance, uniform in thickness, weight, and drug content; showed good mucoadhesive strength; and good folding endurance. A 3² full factorial design was employed to study the effect of independent variables viz. levels of chitosan and PVP K30, which significantly influenced characteristics like swelling index, in-vitro mucoadhesive strength, in vitro drug release, and in-vitro residence time. Different penetration enhancers were tried to improve the permeation of sumatriptan succinate through buccal mucosa. Formulation containing 3% dimethyl sulfoxide showed good permeation of sumatriptan succinate through mucosa. Histopathological studies revealed no buccal mucosal damage. It can be concluded that buccal route can be one of the alternatives available for administration of sumatriptan succinate.     

Lyophilized Sustained Release Mucoadhesive Chitosan Sponges for Buccal Buspirone Hydrochloride Delivery: Formulation and In Vitro Evaluation

This work aims to prepare sustained release buccal mucoadhesive lyophilized chitosan sponges of buspirone hydrochloride (BH) to improve its systemic bioavailability. Chitosan sponges were prepared using simple casting/freeze-drying technique according to 3² factorial design where chitosan grade was set at three levels (low, medium, and high molecular weight), and concentration of chitosan solution at three levels (0.5, 1, and 2%). Mucoadhesion force, ex vivo mucoadhesion time, percent BH released after 8 h (Q8h), and time for release of 50% BH (T_50%) were chosen as dependent variables. Additional BH cup and core buccal chitosan sponge were prepared to achieve uni-directional BH release toward the buccal mucosa. Sponges were evaluated in terms of drug content, surface pH, scanning electron microscopy, swelling index, mucoadhesion strength, ex vivo mucoadhesion time, and in vitro drug release. Cup and core sponge (HCH 0.5E) were able to adhere to the buccal mucosa for 8 h. It showed Q8h of 68.89% and exhibited a uni-directional drug release profile following Higuchi diffusion model.KEY WORDS: buspirone HCL, casting/freeze-drying technique, chitosan, cup and core sponge, mucoadhesive buccal sponges     

The effect of short-term, high glucose concentration on endothelial cells and leukocytes in a 3D in vitro human vascular tissue model

Efforts to determine a link between diabetes and atherosclerosis have involved examining the effect of high glucose levels on the adhesion and migration of circulating leukocytes, mostly monocytes and T lymphocytes. Leukocyte differentiation and proliferation within the subendothelial space can also be investigated by the use of a 3D in vitro human vascular tissue model. This model was used to study the effect of short-term, high glucose concentration on certain cell behavior associated with the early stages of atherosclerosis. Samples were exposed to either a 30- or 5.6-mM glucose concentration for 9 h to represent either hyperglycemic or normoglycemic conditions, respectively. There was a significant increase in vascular cell adhesion molecule-1 expression on the endothelial cells exposed to a 30-mM compared to a 5.6-mM glucose concentration. There was no significant difference in either intercellular adhesion molecule-1 or E-selectin expression on the endothelial cells exposed to a 30-mM compared to a 5.6-mM glucose concentration. After the endothelium was exposed to 30 mM glucose concentration, there was a 70% increase in the number of monocytes (CD14⁺) migrating across the endothelium and a 28% increase in the number of these monocytes differentiating into macrophages, compared to cell migration and differentiation across the endothelium exposed to 5.6 mM glucose concentration. Also, for the endothelium exposed to 30 mM glucose concentration, there were nearly 2.5 times more T lymphocytes that migrated across the endothelium, along with significant cell proliferation, compared to cell migration across the endothelium exposed to 5.6 mM glucose concentration.     

Mucoadhesive nanoparticles may disrupt the protective human mucus barrier by altering its microstructure

Mucus secretions typically protect exposed surfaces of the eyes and respiratory, gastrointestinal and female reproductive tracts from foreign entities, including pathogens and environmental ultrafine particles. We hypothesized that excess exposure to some foreign particles, however, may cause disruption of the mucus barrier. Many synthetic nanoparticles are likely to be mucoadhesive due to hydrophobic, electrostatic or hydrogen bonding interactions. We therefore sought to determine whether mucoadhesive particles (MAP) could alter the mucus microstructure, thereby allowing other foreign particles to more easily penetrate mucus. We engineered muco-inert probe particles 1 μm in diameter, whose diffusion in mucus is limited only by steric obstruction from the mucus mesh, and used them to measure possible MAP-induced changes to the microstructure of fresh human cervicovaginal mucus. We found that a 0.24% w/v concentration of 200 nm MAP in mucus induced a ～10-fold increase in the average effective diffusivity of the probe particles, and a 2- to 3-fold increase in the fraction capable of penetrating physiologically thick mucus layers. The same concentration of muco-inert particles, and a low concentration (0.0006% w/v) of MAP, had no detectable effect on probe particle penetration rates. Using an obstruction-scaling model, we determined that the higher MAP dose increased the average mesh spacing ("pore" size) of mucus from 380 nm to 470 nm. The bulk viscoelasticity of mucus was unaffected by MAP exposure, suggesting MAP may not directly impair mucus clearance or its function as a lubricant, both of which depend critically on the bulk rheological properties of mucus. Our findings suggest mucoadhesive nanoparticles can substantially alter the microstructure of mucus, highlighting the potential of mucoadhesive environmental or engineered nanoparticles to disrupt mucus barriers and cause greater exposure to foreign particles, including pathogens and other potentially toxic nanomaterials.     

Overview and Future Potential of Buccal Mucoadhesive Films as Drug Delivery Systems for Biologics

The main route of administration for drug products is the oral route, yet biologics are initially developed as injectables due to their limited stability through the gastrointestinal tract and solubility issues. In order to avoid injections, a myriad of investigations on alternative administration routes that can bypass enzymatic degradation and the first-pass effect are found in the literature. As an alternative site for biologics absorption, the buccal route presents with a number of advantages. The buccal mucosa is a barrier, providing protection to underlying tissue, but is more permeable than other alternative routes such as the skin. Buccal films are polymeric matrices designed to be mucoadhesive properties and usually formulated with permeability enhancers to improve bioavailability. Conventionally, buccal films for biologics are manufactured by solvent casting, yet recent developments have shown the potential of hot melt extrusion, and most recently ink jet printing as promising strategies. This review aims at depicting the field of biologics-loaded mucoadhesive films as buccal drug delivery systems. In light of the literature available, the buccal epithelium is a promising route for biologics administration, which is reflected in clinical trials currently in progress, looking forward to register and commercialize the first biologic product formulated as a buccal film.     

Solubilization of pituitary receptors for thyrotropin-releasing hormone

Receptors for thyrotropin-releasing hormone were solubilized by Triton X-100. Membrane fractions from GH₃ pituitary tumor cells were incubated with thyrotropin-releasing hormone in order to saturate specific receptor sites before the addition of detergent. The amount of protein-bound hormone solubilized by Triton X-100 was proportional to the fractional saturation of specific membrane receptors. Increasing detergent: protein ratios from 0.5 to 20 led to a progressive loss of hormone · receptor complex from membrane fractions with a concomitant increase in soluble protein-bound hormone. The soluble hormone · receptor complex was not retained by 0.22 μm filters and remained soluble after ultracentrifugation. Following incubation with high (2.5–10%) concentration of Triton X-100 and other non-ionic detergents, or following repeated detergent extraction, at least 18% of specifically bound thyrotropin-releasing hormone remained associated with particulate material. Unlike the hormone receptor complex, the free hormone receptor was inactivated by Triton X-100. A 50% loss of binding activity was obtained with 0.01% Triton X-100, corresponding to a detergent: protein ratio of 0.033.The hormone · receptor complex was included in Sepharose 6B and exhibited an apparent Stokes radius of 46 Å in buffers containing Triton X-100. The complex aggregated in detergent-free buffers. Soluble hormone receptors were separated from excess detergent and thyrotropin-releasing hormone by chromatography on DEAE-cellulose. Thyrotropin-releasing hormone dissociated from soluble receptors with a half-time of 120 min at 0°c, while the membrane hormone · receptor complex was stable for up to 5 h at 0°C.     

Expression of genomic AtCYCD2;1 in Arabidopsis induces cell division at smaller cell sizes: implications for the control of plant growth

The Arabidopsis (Arabidopsis thaliana) CYCD2;1 gene introduced in genomic form increased cell formation in the Arabidopsis root apex and leaf, while generating full-length mRNA, raised CDK/CYCLIN enzyme activity, reduced G1-phase duration, and reduced size of cells at S phase and division. Other cell cycle genes, CDKA;1, CYCLIN B;1, and the cDNA form of CYCD2;1 that produced an aberrantly spliced mRNA, produced smaller or zero increases in CDK/CYCLIN activity and did not increase the number of cells formed. Plants with a homozygous single insert of genomic CYCD2;1 grew with normal morphology and without accelerated growth of root or shoot, not providing evidence that cell formation or CYCLIN D2 controls growth of postembryonic vegetative tissues. At the root apex, cells progressed normally from meristem to elongation, but their smaller size enclosed less growth and a 40% reduction in final size of epidermal and cortical cells was seen. Smaller elongated cell size inhibited endoreduplication, indicating a cell size requirement. Leaf cells were also smaller and more numerous during proliferation and epidermal pavement and palisade cells attained 59% and 69% of controls, whereas laminas reached normal size. Autonomous control of expansion was therefore not evident in abundant cell types that formed tissues of root or leaf. Cell size was reduced by a greater number formed in a tissue prior to cell and tissue expansion. Initiation and termination of expansion did not correlate with cell dimension or number and may be determined by tissue-wide signals acting across cellular boundaries.