Ultrasound-assisted surface engineering of pharmaceutical powders

Effective processing of powdered particles can facilitate powder handling and result in better drug product performance, which is of great importance in the pharmaceutical industry where the majority of active pharmaceutical ingredients (APIs) are delivered as solid dosage forms. The purpose of this work was to develop a new ultrasound-assisted method for particle surface modification and thin-coating of pharmaceutical powders. The ultrasound was used to produce an aqueous mist with or without a coating agent. By using the proposed technique, it was possible to decrease the interparticular interactions and improve rheological properties of poorly-flowing water-soluble powders by aqueous smoothing of the rough surfaces of irregular particles. In turn, hydrophilic polymer thin-coating of a hydrophobic substance diminished the triboelectrostatic charge transfer and improved the flowability of highly cohesive powder. To determine the coating efficiency of the technique, the bioactive molecule β-galactosidase was layered onto the surface of powdered lactose particles. Enzyme-treated materials were analysed by assaying the quantity of the reaction product generated during enzymatic cleavage of the milk sugar. A near-linear increase in the thickness of the drug layer was obtained during progressive treatment. Using the enzyme coating procedure, it was confirmed that the ultrasound-assisted technique is suitable for processing labile protein materials. In addition, this pre-treatment of milk sugar could be used to improve utilization of lactose-containing formulations for populations suffering from severe lactose intolerance. Furthermore, the applicability of the thin-coating technique for improving homogeneity of low-dose solid dosage forms was shown. The carrier particles coated with API gave rise to uniform distribution of the drug within the powder. The mixture remained homogeneous during further tabletting, whereas the reference physical powder mixture was subject to segregation. In conclusion, ultrasound-assisted surface engineering of pharmaceutical powders can be effective technology for improving formulation and performance of solid dosage forms such as dry powder inhalers (DPI) and direct compression products.

Perception of surface brightness

The human visual system has adapted to function in different lighting environments and responds to contrast instead of the amount of light as such. On the one hand, this ensures constancy of perception, for example, white paper looks white both in bright sunlight and in dim moonlight, because contrast is invariant to changes in overall light level. On the other hand, the brightness of the surfaces has to be reconstructed from the contrast signal because no signal from surfaces as such is conveyed to the visual cortex. In the visual cortex, the visual image is decomposed to local features by spatial filters that are selective for spatial frequency, orientation, and phase. Currently it is not known, however, how these features are subsequently integrated to form objects and object surfaces. In this thesis the integration mechanisms of achromatic surfaces were studied by psychophysically measuring the spatial frequency and orientation tuning of brightness perception. In addition, the effect of textures on the spread of brightness and the effect of phase of the inducing stimulus on brightness were measured. The novel findings of the thesis are that (1) a narrow spatial frequency band, independent of stimulus size and complexity, mediates brightness information (2) figure-ground brightness illusions are narrowly tuned for orientation (3) texture borders, without any luminance difference, are able to block the spread of brightness, and (4) edges and even- and odd-symmetric Gabors have a similar antagonistic effect on brightness. The narrow spatial frequency tuning suggests that only a subpopulation of neurons in V1 is involved in brightness perception. The independence of stimulus size and complexity indicates that the narrow tuning reflects hard-wired processing in the visual system. Further, it seems that figure-ground segregation and mechanisms integrating contrast polarities are closely related to the low level mechanisms of brightness perception. In conclusion, the results of the thesis suggest that a subpopulation of neurons in visual cortex selectively integrates information from different contrast polarities to reconstruct surface brightness.

Preventive orientation and caries management by Iranian dentists

Ehkäisypainotteisuus karieksen hoidossa: iranilaishammaslääkärien hoitovalinnat Karies aiheuttaa hampaiden kovan pinnan ja hammasluun syöpymistä, joka lopulta näkyy ”reikänä”. Iästä riippumatta kariesvaara vaanii kaikkia hampaiden omistajia, vauvasta vaariin, ja lähes kaikilla aikuisilla on suussaan merkkejä karieksesta. Karies etenee yleensä hitaasti ja antaa siten aikaa ehkäisevälle hoidolle. Tämä etsikkoaika jää usein käyttämättä, ja karieksen hoito painottuu reikien paikkaamiseen. Karies voitaisiin pitää kurissa sen ehkäisyyn kehitetyillä monipuolisilla keinoilla. Hammaslääkärit ovat avainasemassa, sillä he tekevät kauaskantoisia valintoja — hoidetaanko kariesta paikkaamalla vai valitaanko ehkäisevä hoito? Valintojen taustalla ovat hammaslääkärin tietotaso, asenteet ja omat terveystavat sekä potilaiden ja vastaanoton aiheuttamiksi koetut esteet. Tämä kyselytutkimus selvitti karieksen hoitovalintoja ja niiden taustoja Iranissa. Kysymyslomakkeet jaettiin kahdessa hammaslääkärien kongressissa Teheranissa (2004─2005) ja palautettiin nimettöminä. Kysely kartoitti hammaslääkärien tietoja karieksen ehkäisykeinoista ja asenteita ehkäisyä kohtaan sekä koettuja esteitä sen toteuttamisessa. Hoitovalintoja selvitettiin tarkasti kuvattujen esimerkkipotilaiden avulla. Kysely kartoitti myös hammaslääkärien omat terveystavat: suun omahoidon, tupakoinnin ja hammaslääkärissä käynnin. Aineisto käsitti 980 iältään keskimäärin 37-vuotiasta hammaslääkäriä, joista 64 % oli miehiä. Iranilaishammaslääkärien tiedot karieksen ehkäisystä olivat fluorihammastahnan merkitystä lukuun ottamatta hyvät ja heidän asenteensa ehkäisyä kohtaan valtaosin myönteiset. Tästä huolimatta 77 % heistä olisi valinnut suuren kariesvaaran potilaalle hammaskiilteessä olevan reiän hoidoksi paikkauksen. Ehkäisyhoidoksi tarjotuista 8:sta keinosta lähes kaikki hammaslääkärit valitsivat suuren kariesvaaran potilaalle hoidoksi harjausopetuksen ja säännölliset hammastarkastukset, noin 80 % valitsi hampaiden puhdistamisen vastaanotolla ja ravintoneuvonnan, 70 % ohjeet fluorihuuhteluista kotona ja 53 % vastaanotolla tehtävän fluorikäsittelyn. Potilaiden vastustavat mielipiteet arvioitiin suurimmaksi esteeksi ehkäisevän hoidon toteuttamiselle. Hammaslääkäreistä 59 % ilmoitti harjaavansa hampaansa kahdesti päivässä; 76 % ei tupakoinut ja 56 % kertoi aina ehdottavansa tupakoivalle potilaalle tupakoinnin lopettamista. Hammaslääkärien ehkäisypainotteisuus karieshoidossa oli naisilla vahvempi kuin miehillä. Tulosten perusteella voi päätellä, että Iranissa tulisi nykyistä selvemmin suosia ehkäisevää linjaa karieksen hoitovalintoja tehtäessä ja hammaslääkäreitä koulutettaessa. Potilastyössä koettujen ehkäisyhoidon esteiden syvällisempi ymmärtäminen edesauttaisi niiden poistamisessa.

Arresting occlusal enamel caries lesions with pit and fissure sealants

The aim of this study was to evaluate the feasibility of pit and fissure sealants and the effectiveness of the two sealant methods applied in every-day practice in public dental health care in Finland. Two sealant methods were evaluated according to their effectiveness in preventing dentin caries and sealant retention. Application time with these sealant methods was compared. The survival rate of sealed first and second molars was followed for nine and 13 year periods, respectively. Caries risk evaluation and observed increased caries risk were the basis for considering sealant application. A questionnaire, sent to all public dental health centers in Finland, monitored the attitudes of the dental profession towards sealant application and explored the current policies used as well as changes noted in the sealant application protocol. DMFT (Decayed, Missing or Filled Teeth) index values collected from the health centers were evaluated. The difference in caries rate between two methods investigated was highly significant. When compared to the glass ionomer sealant method (GIC), the effectiveness of the resin-based method (RB) in preventing dentin caries was 74% and the rate difference 3%. The relative risk for RB-sealed surfaces vs. GIC-sealed surfaces of having detectable dentin caries was 0.3 (95% CI 0.12, 0.57). The retention rate of sealants was higher with RB than GIC (P<0.001). Application of RB sealant material was less time-consuming than application of GIC sealant. Occlusal dentin caries lesions were found in 4% and proximal caries in less than 2% of sealed teeth. The majority of respondents reported application of sealants on a systematic basis along with caries-risk evaluation. Those health centers sealing over suspected or detected enamel caries had lower average DMFT index values (1.0) when compared to DMFT values (1.2) of health centers applying sealants by alternative criteria. It is concluded that the RB sealant method is more effective than the GIC sealant method in preventing dentin caries. Sealant maintenance may increase the costs of a sealant program. Occlusal caries management may be improved if the applied sealant policies are changed towards an interceptive approach i.e. applying the sealants over detected or suspected enamel caries lesions instead of sealing sound teeth in a preventive manner.

Early Childhood Caries and a Community Trial of its Prevention in Tehran, Iran

Varhaislapsuuden karies ja sen ehkäisy kehittyvän terveydenhuollon maassa Varhaislapsuuden karies on merkittävä kansanterveysongelma varsinkin lapsirikkaissa maissa ja väestöissä. Karieksen hoitaminen vie paljon voimavaroja ja aiheuttaa mittavia taloudellisia seuraamuksia. Karies voi ilmaantua lapselle jo vauvaikäisenä, pian ensimmäisten maitohampaiden puhjettua suuhun. Alle 3-vuotiaiden karieksesta on kuitenkin niukasti tilastotietoja. Maailman terveysjärjestökin suosittaa tietojen keräämistä vasta 3-vuotiaiden ikäryhmästä. Heistä kariesta sairastaa Suomessa 16 %, Yhdysvalloissa 25 %, Englannissa 30 %, Iranissa 46 % ja Saudi-Arabiassa 61 %. Tämä väitöstutkimus selvitti karieksen esiintymistä ja sen vaaratekijöitä 1─3-vuotiailla Teheranissa. Lisäksi tutkimus arvioi perusterveydenhuoltoon sisällytetyn karieksen ehkäisyn tuloksellisuutta. Tutkimuskohteiksi arvottiin Teheranista 18 neuvolaa. Jokaisessa oltiin 4 päivää, jolloin kaikkia rokotuksiin tulleita 1─3-vuotiaita äiteineen pyydettiin osallistumaan tutkimukseen. Kahta lukuun ottamatta kaikki äidit suostuivat, ja aineistoon tuli kaikkiaan 504 lasta äiteineen. Kaikki 1-vuotiaat, 242 lasta äiteineen, valittiin karieksen ehkäisykokeiluun. Sitä varten neuvolat jaettiin kolmeen ryhmään, joista kaksi (A ja B) oli koeryhmiä ja yksi (C) oli vertailuryhmä. Tutkimus alkoi äidin haastattelulla. Siinä selvitettiin perheen koulutus- ja tulotaso sekä lapsen ruokinnasta imetyksen kesto, yösyötöt ja päiväaikaan nautitut makeat. Vielä kysyttiin lapsen ja äidin suuhygieniatavoista ja äidin kokemuksista lapsen suun puhdistamisessa. Sitten hammaslääkäri tutki lapsen suun ja kirjasi karieksen ja hammasplakin esiintymät. Suun tutkimuksen jälkeen äiti ja lapsi siirtyivät rokotushuoneeseen. Koeryhmissä (A ja B) äidit saivat terveydenhoitajalta suunterveyttä koskevan esitteen ja kehotuksen lukea se huolellisesti. Lisäksi ryhmässä A terveydenhoitaja kertoi suun ja hampaiden terveydenhoidosta saman esitteen avulla, ja neuvolan henkilökunta muistutti suunhoidon tärkeydestä puhelimitse kahdesti seuraavan puolen vuoden kuluessa. Vertailuryhmässä äideille ei annettu suunhoidon ohjeita. Kaikissa ryhmissä äitejä muistutettiin seuraavan rokotuskerran ajankohdasta, muttei mainittu tulevaa toista hammastarkastusta. Varhaislapsuuden kariesta sairasti ikäryhmästä riippuen 3─26 % tutkituista 1─3-vuotiaista, ja 65─76 %:lla oli hammasplakkia. Äideistä 68 % harjasi hampaansa päivittäin ja 39 % puhdisti lapsensa suun päivittäin. Mitä useammin äiti harjasi omat hampaansa, sitä paremmin hän huolehti lapsen suun puhtaudesta. Rintaruokinta oli yleistä eikä lisännyt kariesvaaraa. Yöllä pullomaitoa saavilla karies oli 5 kertaa yleisempää kuin muilla. Neuvolassa saatu ohjeistus ehkäisi selvästi karieksen syntyä puolen vuoden kokeessa.

Modifications of surface materials and their effects on cleanability as studied by radiochemical methods

Modifications of surface materials and their effects on cleanability have important impacts in many fields of activity. In this study the primary aim was to develop radiochemical methods suitable for evaluating cleanability in material research for different environments. Another aim was to investigate the effects of surface modifications on cleanabilitity and surface properties of plastics, ceramics, concrete materials and also their coatings in conditions simulating their typical environments. Several new 51Cr and 14C labelled soils were developed for testing situations. The new radiochemical methods developed were suitable for examining different surface materials and different soil types, providing quantitative information about the amount of soil on surfaces. They also take into account soil soaked into surfaces. The supporting methods colorimetric determination and ATP bioluminescence provided semi-quantitative results. The results from the radiochemical and supporting methods partly correlated with each other. From a material research point of view numerous new materials were evaluated. These included both laboratory-made model materials and commercial products. Increasing the amount of plasticizer decreased the cleanability of poly(vinyl chloride) (PVC) materials. Microstructured surfaces of plastics improved the cleanability of PVC from particle soils, whereas for oil soil microstructuring reduced the cleanability. In the case of glazed ceramic materials, coatings affected the cleanability. The roughness of surfaces correlated with cleanability from particle soils and the cleanability from oil soil correlated with the contact angles. Organic particle soil was removed more efficiently from TiO2-coated ceramic surfaces after UV-radiation than without UV treatment, whereas no effect was observed on the cleanability of oil soil. Coatings improved the cleanability of concrete flooring materials intended for use in animal houses.

Feasibility of assimilating ASCAT surface winds into a Limited Area Model

Sea-surface wind observations of previous generation scatterometers have been successfully assimilated into Numerical Weather Prediction (NWP) models. Impact studies conducted with these assimilation implementations have shown a distinct improvement to model analysis and forecast accuracies. The Advanced Scatterometer (ASCAT), flown on Metop-A, offers an improved sea-surface wind accuracy and better data coverage when compared to the previous generation scatterometers. Five individual case studies are carried out. The effect of including ASCAT data into High Resolution Limited Area Model (HIRLAM) assimilation system (4D-Var) is tested to be neutral-positive for situations with general flow direction from the Atlantic Ocean. For northerly flow regimes the effect is negative. This is later discussed to be caused by problems involving modeling northern flows, and also due to the lack of a suitable verification method. Suggestions and an example of an improved verification method is presented later on. A closer examination of a polar low evolution is also shown. It is found that the ASCAT assimilation scheme improves forecast of the initial evolution of the polar low, but the model advects the strong low pressure centre too fast eastward. Finally, the flaws of the implementation are found small and implementing the ASCAT assimilation scheme into the operational HIRLAM suite is feasible, but longer time period validation is still required.

Surface Proteins of Lactobacillus crispatus: Adhesive Properties and Cell Wall Anchoring

Bacterial surface-associated proteins are important in communication with the environment and bacteria-host interactions. In this thesis work, surface molecules of Lactobacillus crispatus important in host interaction were studied. The L. crispatus strains of the study were known from previous studies to be efficient in adhesion to intestinal tract and ECM. L. crispatus JCM 5810 possess an adhesive surface layer (S-layer) protein, whose functions and domain structure was characterized. We cloned two S-layer protein genes (cbsA; collagen-binding S-layer protein A and silent cbsB) and identified the protein region in CbsA important for adhesion to host tissues, for polymerization into a periodic layer as well as for attachment to the bacterial cell surface. The analysis was done by extensive mutation analysis and by testing His6-tagged fusion proteins from recombinant Escherichia coli as well as by expressing truncated CbsA peptides on the surface of Lactobacillus casei. The N-terminal region (31-274) of CbsA showed efficient and specific binding to collagens, laminin and extracellular matrix on tissue sections of chicken intestine. The N-terminal region also contained the information for formation of periodic S-layer polymer. This region is bordered at both ends by a conserved short region rich in valines, whose substitution to leucines drastically affected the periodic polymer structure. The mutated CbsA proteins that failed to form a periodic polymer, did not bind collagens, which indicates that the polymerized structure of CbsA is needed for collagen-binding ability. The C-terminal region, which is highly identical in S-layer proteins of L. crispatus, Lactobacillus acidophilus and Lactobacillus helveticus, was shown to anchor the protein to the bacterial cell wall. The C-terminal CbsA peptide specifically bound to bacterial teichoic acid and lipoteichoic acids. In conclusion, the N-terminal domain of the S-layer protein of L. crispatus is important for polymerization and adhesion to host tissues, whereas the C-terminal domain anchors the protein to bacterial cell-wall teichoic acids. Lactobacilli are fermentative organisms that effectively lower the surrounding pH. While this study was in progress, plasminogen-binding proteins enolase and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) were identified in the extracellular proteome of L. crispatus ST1. In this work, the cell-wall association of enolase and GAPDH were shown to rely on pH-reversible binding to the cell-wall lipoteichoic acids. Enolase from L. crispatus was functionally compared with enolase from L. johnsonii as well as from pathogenic streptococci (Streptococcus pneumoniae, Streptococcus pyogenes) and Staphylococcus aureus. His6-enolases from commensal lactobacilli bound human plasminogen and enhanced its activation by human plasminogen activators similarly to, or even better than, the enolases from pathogens. Similarly, the His6-enolases from lactobacilli exhibited adhesive characteristics previously assigned to pathogens. The results call for more detailed analyses of the role of the host plasminogen system in bacterial pathogenesis and commensalism as well of the biological role and potential health risk of the extracellular proteome in lactobacilli.