Prominin-1 controls stem cell activation by orchestrating ciliary dynamics.

Proper temporal and spatial activation of stem cells relies on highly coordinated cell signaling. The primary cilium is the sensory organelle that is responsible for transmitting extracellular signals into a cell. Primary cilium size, architecture, and assembly-disassembly dynamics are under rigid cell cycle-dependent control. Using mouse incisor tooth epithelia as a model, we show that ciliary dynamics in stem cells require the proper functions of a cholesterol-binding membrane glycoprotein, Prominin-1 (Prom1/CD133), which controls sequential recruitment of ciliary membrane components, histone deacetylase, and transcription factors. Nuclear translocation of Prom1 and these molecules is particularly evident in transit amplifying cells, the immediate derivatives of stem cells. The absence of Prom1 impairs ciliary dynamics and abolishes the growth stimulation effects of sonic hedgehog (SHH) treatment, resulting in the disruption of stem cell quiescence maintenance and activation. We propose that Prom1 is a key regulator ensuring appropriate response of stem cells to extracellular signals, with important implications for development, regeneration, and diseases.

Binding of phosphorothioate oligonucleotides to zwitterionic liposomes.

Although double-stranded DNA (dsDNA) has been shown to bind to zwitterionic lipids, it has been reported that this association is stronger for disordered (L(alpha)) phase lipids than for well-ordered (L(beta)) lipids. In this work, the interaction of single-strand phosphorothioate oligonucleotides (ONs) with unilamellar liposomes of saturated and unsaturated zwitterionic phosphocholines (PCs) and phosphoroethylamine (PE) was investigated. It is shown that the association of phosphorothioate ONs to diacyl glycerophosphocholines is strong, but only for L(beta) phase or otherwise ordered bilayers. There is no measurable affinity for PE lipids. The apparent affinity of three different phosphorothioate ONs for L(beta) phase 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) has been measured and the dissociation constants were on the order of 10(-7) M. Purine-rich ON sequences had stronger binding to DPPC liposomes than did pyrimidine-rich sequences, but there were other sequence-dependent factors. This exceptionally high affinity could be an important consideration in ON uptake, delivery, and biodistribution.

Liposomal dry powders as aerosols for pulmonary delivery of proteins.

The purpose of this research was to develop liposomal dry powder aerosols for protein delivery. The delivery of stable protein formulations is essential for protein subunit vaccine delivery, which requires local delivery to macrophages in the lungs. Beta-glucuronidase (GUS) was used as a model protein to evaluate dry powder liposomes as inhaled delivery vehicles. Dimyristoyl phosphatylcholine:cholesterol (7:3) was selected as the liposome composition. The lyophilization of liposomes, micronization of the powders, aerosolization using a dry powder inhaler (DPI), and in vitro aerodynamic fine particle fraction upon collection in a twin-stage liquid impinger were evaluated. After lyophilization and jet-milling, the total amount of GUS and its activity, representing encapsulation efficiency and stability, were evaluated. The GUS amount and activity were measured and compared with freshly-prepared liposomes in the presence of mannitol, 43% of initial GUS amount, 29% of GUS activity after lyophilization and 36% of GUS amount, 22% of activity after micronization were obtained. Emitted doses from dry powder inhaler were 53%, 58%, 66%, and 73% for liposome powder:mannitol carrier ratios of 1:0, 1:4, 1:9, and 1:19. Fifteen percent of the liposome particles were less than 6.4 mum in aerodynamic diameter. The results demonstrate that milled liposome powders containing protein molecules can be aerosolized effectively at a fixed flow rate. Influences of different cryoprotectants on lyophilization of protein liposome formulations are reported. The feasibility of using liposomal dry powder aerosols for protein delivery has been demonstrated but further optimization is required in the context of specific therapeutic proteins.

[Fracture resistance of the all-ceramic posts in post-and-core system].

OBJECTIVE: To make a comparative study on the fracture resistance of the all-ceramic posts in post-and-core system where the ceramic core was combined with the post by direct sintering and by two other methods. METHODS: A total of 15 all-ceramic posts fabricated by alumina-zirconia nano-composite infiltrated ceramics were randomly divided into three groups. They were given the following treatments: Group A: forming and combining the ceramic core with the post by direct sintering; group B: combining the ceramic core with the post by use of 3M RelyX for adhesion; group C: forming composite resin core onto the post. Each specimen was placed into a special jig and subjected to a load perpendicular to the post axis on INSTRON 4302 universal testing instrument until failure. ANOVA was used for statistical analysis. RESULTS: There was no statistically significant difference between the groups (P>0.05). CONCLUSION: The findings indicate that the strength of the post remains uninfluenced during the combination of the core with the post by direct sintering.

Pulmonary immunization using antigen 85-B polymeric microparticles to boost tuberculosis immunity.

This study aims to evaluate immunization with polymeric microparticles containing recombinant antigen 85B (rAg85B) delivered directly to the lungs to protect against tuberculosis. rAg85B was expressed in Escherichia coli and encapsulated in poly(lactic-co-glycolic acid) microparticles (P-rAg85B). These were delivered as dry powders to the lungs of guinea pigs in single or multiple doses of homologous and heterologous antigens. Bacille Calmette-Guérin (BCG) delivered subcutaneously was employed as the positive control and as part of immunization strategies. Immunized animals were challenged with a low-dose aerosol of Mycobacterium tuberculosis (MTB) H37Rv to assess the extent of protection measured as reduction in bacterial burden (CFU) in the lungs and spleens of guinea pigs. Histopathological examination and morphometric analysis of these tissues were also performed. The heterologous strategy of BCG prime-P-rAg85B aerosol boosts appeared to enhance protection from bacterial infection, as indicated by a reduction in CFU in both the lungs and spleens compared with untreated controls. Although the CFU data were not statistically different from the BCG and BCG-BCG groups, the histopathological and morphometric analyses indicated the positive effect of BCG-P-rAg85B in terms of differences in area of tissue affected and number and size of granulomas observed in tissues. P-rAg85B microparticles appeared to be effective in boosting a primary BCG immunization against MTB infection, as indicated by histopathology and morphometric analysis. These encouraging observations are relevant to boosting adults previously immunized with BCG or exposed to MTB, commonly the case in the developing world, and should be followed by further assessment of an appropriate immunization protocol for maximum protection.

Screening for potential adjuvants administered by the pulmonary route for tuberculosis vaccines.

Tuberculosis (TB) infects one third of the world's population, and new infections occur at a rate of 1/s. Better vaccines are needed than the live mycobacterium Bacille Calmette-Guérin (BCG). Alveolar macrophages (AMPhis) play a central role in pulmonary manifestations of TB. Targeting immunomodulators to AMPhis, the first line of defense against Mycobacterium tuberculosis (Mtb), may initiate a potent cell-mediated immune response. Muramyl dipeptide (MDP) and trehalose dibehenate (TDB) have elicited strong immune response when delivered to the lungs as aerosols. AMPhis show toxicity in response to some immunomodulators. The objective of this work was to screen the immunomodulators MDP and/or TDB encapsulated in microparticles (MPs) and to evaluate certain indicators of toxicity in human AMPhi-like cells. Poly(lactide-co-glycolide) (PLGA) MPs containing MDP and/or TDB were prepared by spray-drying. The morphology, particle size distribution, and immunomodulator encapsulation efficiency of MPs were examined. THP-1 cells were exposed to these MPs for 24 h and characteristics of cell morphology, tumor necrosis factor-alpha (TNF-alpha) release, lactate dehydrogenase (LDH), N-acetyl-beta-D: -glucosaminidase (NAG) and alkaline phosphatase (ALP) activity in AMPhi culture supernatants were measured. MTT assay was used to assess the viability of cells. Spray-drying produced low-density MPs having volume median diameters between 4 and 6 microm as measured by laser diffraction and projected area diameter between 3 and 5 microm calculated by microscopy. More TNF-alpha was produced by THP-1 cells exposed to MPs composed of PLGA-MDP or PLGA alone than PLGA-TDB. LDH release following exposure to MPs of PLGA-MDP and PLGA alone was greater than controls. NAG release was higher following exposure to MPs of PLGA alone or PLGA-MDP 0.1% than PLGA-TDB (0.1% and 1.0%). Cells remained viable after exposure to MPs as per MTT assay. PLGA-MDP MPs demonstrated statistically elevated indicators of biochemical responses in cell culture compared to PLGA-TDB MPs, but the extent of their potential to elicit adverse effects in vivo must be studied independently.

Poly (lactide-co-glycolide) microspheres in respirable sizes enhance an in vitro T cell response to recombinant Mycobacterium tuberculosis antigen 85B.

PURPOSE: To investigate the use of poly (lactide-co-glycolide) (PLGA) microparticles in respirable sizes as carriers for Antigen 85B (Ag85B), a secreted protein of Mycobacterium tuberculosis, with the ultimate goal of employing them in pulmonary delivery of tuberculosis vaccine. MATERIALS AND METHODS: Recombinant Ag85B was expressed from two Escherichia coli strains and encapsulated by spray-drying in PLGA microspheres with/without adjuvants. These microspheres containing rAg85B were assessed for their ability to deliver antigen to macrophages for subsequent processing and presentation to the specific CD4 T-hybridoma cells DB-1. DB-1 cells recognize the Ag85B(97-112) epitope presented in the context of MHC class II and secrete IL-2 as the cytokine marker. RESULTS: Microspheres suitable for aerosol delivery to the lungs (3.4-4.3 microm median diameter) and targeting alveolar macrophages were manufactured. THP-1 macrophage-like cells exposed with PLGA-rAg85B microspheres induced the DB-1 cells to produce IL-2 at a level that was two orders of magnitude larger than the response elicited by soluble rAg85B. This formulation demonstrated extended epitope presentation. CONCLUSIONS: PLGA microspheres in respirable sizes were effective in delivering rAg85B in an immunologically relevant manner to macrophages. These results are a foundation for further investigation into the potential use of PLGA particles for delivery of vaccines to prevent M. tuberculosis infection.

[Microwave sintering of nanometer powder of alumina and zirconia-based dental ceramics].

OBJECTIVE: The objective of the present study was to investigate the feasibility and reliability of sintering alumina and zirconia-based all-ceramic materials through a recently introduced microwave heating technique. The variation of crystal phases, the growth of grain sizes and microstructural features of these materials were evaluated after sintering. METHODS: Four different groups of powder (l00%Al2O3, 60%Al2O3+40%ZrO2, 40% Al2O3+60%ZrO2, 100% ZrO2) were respectively press-compacted to fabricate green disk samples, 5 specimen of each group were prepared. All the samples were surrounded by refractory materials for heat containment and processed at 1 600 degrees C in a domestic microwave oven (850 W, 2 450 MHz), 1 600 degrees C/5 min for heating rate, 10 min for holding time. After sintering, the phase composition and average grain size of these ceramics were examined using X-ray diffraction (XRD). Their microstructure characteristics were studied by scanning electron microscopy (SEM). RESULTS: All the specimens were successfully sintered with the application of microwave heating system in combination with a suitable thermal insulator. No phase change was found in alumina while monoclinic-zirconia was found to be transformed to tetragonal-zirconia. A little grain size growth of Al2O3 and ZrO2 has been observed with Al2O3 24.1 nm/before and 51.8 nm/after; ZrO2 25.3 nm/before and 29.7 nm/after. The SEM photos indicated that the microwave-sintered Al2O3-ZrO2 ceramics had a uniform crystal distribution and their crystal sizes could be maintained within the range of nanometers. CONCLUSION: It is expected that in the near future microwave heating system could be a promising substitute for conventional processing methods due to its unparalled advantages, including more rapid heating rate, shortened sintering time, superfine grain size, improved microstructure and much less expensive equipment.