A high throughput quantitation protocol is desired to determine the replication of various recombinant oncolytic viruses in vitro. Plaque assay is the classic method for viral infectivity quantitation but is laborious and time consuming; moreover it does not report the oncolytic efficacy of a virus. In this paper, three new imaging methods for quantitating viral infectivity are derived and evaluated: fluorescence intensity, infection counts, and infection degree. Infection of oncolytic Newcastle disease virus in human tumor and normal cells was followed over a time course by plaque assay and the imaging methods. For the latter, brightfield and green channel images were acquired at various fixed locations in the cell culture, and later analyzed. One of the imaging methods was found to be highly correlated with viral titer; the other methods are complementary to plaque assay and provide additional information like oncolytic efficacy, syncytium formation etc. The new methods significantly reduce the time and material costs required by plaque assay, and provide an efficient system for quantitating and characterizing infectivity and efficacy of oncolytic viruses.

The effect on the viscoelastic behaviour, of pressure-treating hydrated gum arabic samples (800 MPa) at different pH values (2.8, 4.2 and 8.0) was investigated, using controlled stress rheometry. The treated samples were analysed for their complex (G∗), storage (G′) and loss (G″) moduli as a function of frequency, using dynamic oscillatory testing. Significant changes in the rheological properties were observed in both the pressurised gum solutions and in those previously buffered at pH 2.8. The gum, at its natural pH (4.25) and at alkaline pH (8.0), was enhanced by pressure treatment, but only for the already "good" quality gum samples. High-pressure treatment had substantial effects on the frequency-dependence of the moduli of both the pressurised and the pressurised/pH-treated solutions, with the latter being more pronounced, suggesting differing structures or changes in the overall degree of interaction of the gum systems after pressure treatment.

ABSTRACTThe effects on the viscoelastic behavior of hydrated wheat gluten after treatment at different pressures (200–800 MPa), temperatures (20, 40, and 60°C), and holding times (20 and 50 min) were investigated by controlled stress rheometry. Because of the wide range of properties, four different torque amplitudes were used (0.5, 1.00, 3.00, and 6.00 mNm). Significant effects on rheological properties were observed, except when samples were analyzed at 0.5 mNm (limited heat and pressure treatments). Both storage modulus (G′) and loss modulus (G″) were more affected by temperature than pressure. The holding time had substantial effect on the slopes of both moduli at mild treatments; for the more severe treatments, the intercepts of the storage moduli in particular were extensively affected.

Fractionation and reconstitution/fortification techniques were utilised to study the role of gluten in Arabic bread. Glutens from two wheat cultivars of contrasting breadmaking quality were fractionated by dilute HCl into gliadin and glutenin. Gluten, gliadin and glutenin doughs from the good quality flour had higher G ′ and lower tan δ values than those from the poor quality flour at all the frequencies examined. Interchanging the gliadin and glutenin fractions between the reconstituted flours showed that the glutenin fraction is largely responsible for differences in the breadmaking performance. Fortification of an average quality flour with the gliadin and glutenin fractions from the poor and good quality flours, at the levels of 1% and 2% (protein to flour mass), induced marked differences in the mechanical properties of bread. The resilience of the loaves was not adversely affected by the addition of gliadins and increased, with a concomitant significant (p<0·05) improvement in quality, at the 2% level of fortification with gliadins from the good quality flour. Addition of glutenin resulted in loaves with leather-like properties that became particularly apparent at the higher level of fortification; the observed deterioration in quality paralleled the increase in the elastic character of the doughs. It is suggested that highly-elastic doughs are not compatible with the rapid expansion of gases at the high-temperature short-time conditions employed in the baking of Arabic bread and that there exists a threshold in dough elasticity beyond which a rapid decline in quality takes place.

The objective of this study was to evaluate the effect of calcium on minerals retention and cheesemaking parameters of milk during manufacture of a model soft cheese. Several batches of both reconstituted skim milk containing 9, 12 and 15% (w/v) and whole milk with 12, 15 and 18% (w/v) of total solids were used to prepare a soft ‘stretchable’ cheese of the mozzarella type. A small amount of added calcium (0.14 mM) influenced the level of minerals and some of the measured cheesemaking parameters (clotting time, weight of whey, protein and fat recovery), but the efficiency of the cheesemaking process was lower than would be expected in commercial terms.

Hydrated wheat gluten samples with moisture contents of about 62.5% ww were subjected to high pressure treatment. The experiments followed a three way factorial design which treated pressures at 200, 400, 600 and 800 MPa, temperatures at 20, 40 and 60°C and times of 20 and 50 minutes as the variables. The treated gluten samples were analysed for structural modifications by texture profile analysis (TPA) to measure hardness, initial moduli and solubility in sodium dodecyl sulphate and sodium dodecyl sulphate plus 2-mercaptoethanol. There was a strong correlation between hardness and the elastic modulus at (55%) strain (r = 0.98). Results obtained revealed that, at 20 °C and 40 °C, pressure could alter gluten structure but at these temperatures disulphide cross-linking only became significant when samples were held at 800 MPa for 50 minutes. Treatments at the highest temperature (60 °C) markedly increased hardness and the degree of disulphide bonding, especially in the pressure range of 400 to 800 MPa (p ≤ 0.001).

Fundamental rheological tests were carried out on wheat flour dough containing protein disulphide isomerase (PDI, E.C. 5.4.3.1.) and compared with their respective controls. The Controlled Stress Rheometer (CSR) and the Dynamic Mechanical Thermal Analyzer (DMTA) were used. Results from these instrumental tests which are essentially non-destructive were compared with results obtained when using a traditional Extensometer. The possibility of PDI duplicating the effect of potassium bromate was evaluated. Fundamental testing provided more information about the structure of the dough when used under a wide range of different testing conditions. The Extensometer, under the conditions used in this work, was better than the CSR and the DMTA for showing the effect of PDI (50ppm, flour basis), which seemed to make the dough more elastic the longer the resting time. Although the effect was basically the same as that produced by potassium bromate, it was not of the same magnitude.

The effects of calcium on the rheology of a model soft cheese at different stages of manufacture have been assessed. Several batches of reconstituted skim milk with 9% w/v and four calcium concentrations (0.14, 0.35, 0.88, 2.2 mM) were used to make a soft stretchable cheese whose rheological characteristics, G' (storage modulus or elastic component) and G' (loss modulus or viscous component), at different stages of manufacture, were measured using a Stress Controlled Rheometer. Calcium had a significant effect on the rheology of the soft cheese; however, it affected each rheological parameter differently.

ABSTRACTThe effect of six techniques for the elevation of the total solids on the rheological properties of labneh were investigated using controlled‐stress dynamic rheometer. All samples exhibited a weak viscoelastic gel structure with the storage modulus (G′) higher than the loss modulus (G″) over all of the measured range. None of the experimental materials produced the same overall gel strength as the control made by draining with traditional cloth‐bags. The changes in the storage modulus (G′) as a function of amplitude sweep were mirrored by changes in the loss modulus (G″). Considerable differences in the loss tangent (G”/G′) values of the various materials were observed at higher stress amplitudes. Rheological differences in the overall gel strength at low amplitude and frequency suggest that, although the type of protein interactions in each case may be similar, there are differences in the degree of interactions. Subsequent breakdown at higher amplitudes and frequencies suggests that the overall domains of the treated proteins may have been reduced, and that different methods of manufacture may be producing materials that have different space occupancy in the gel.

The dynamic rheological properties of glutens and gluten fractions (gliadin and glutenin) of two U.K.-grown wheat cultivars, Hereward and Riband, having good and poor bread quality, respectively, were studied. Gluten and glutenin doughs from cv. Hereward had higher G' and lower tan δ values than those from cv. Riband at all frequencies studied. A more pronounced difference in G' and tan δ was observed between the glutenin doughs of the two wheats than between their respective gluten doughs. The rheological properties, i.e. G' and tan δ values, of gliadin doughs were similar for both wheats. Varying the gliadin/glutenin ratio by adding the isolated gliadin or glutenin sub-fractions to the parent glutens showed that the G' values decreased and the tan δ values increased as the gliadin/glutenin ratio was increased for both cultivars, indicating a considerable decrease in elasticity as the gliadin/glutenin ratio increased. The decrease in G' may be attributed to a plasticising effect of gliadin and ‘interference’ of gliadin with glutenin-glutenin interactions. The reduction in G' was much more pronounced when the gliadin/glutenin ratio was increased between 0.15 and 1.0 than between 1.0 and above. Gluten from cv. Hereward had higher G' and lower tan δ values than cv. Riband gluten at all gliadin/glutenin ratios, indicating that cv. Hereward gluten had greater elastic character than cv. Riband gluten. Although significant effects of other non-protein hydrocolloid components cannot be discounted, these observations are consistent with the view that the viscoelasticity of the glutenin sub-fraction of gluten and differences in the ratio of gliadin to glutenin are the main factors governing inter-cultivar differences in the viscoelasticity of wheat gluten.

Bovine and caprine milk gels were made by GDL‐acidification and yogurt fermentation (using ‘ropy’ and ‘non‐ropy’ starter cultures). The respective gelation processes were monitored rheologically using dynamic oscillatory testing. The bovine fermented systems produced gel structures with about half the strength of the equivalent chemically acidified gels. The fermented caprine milk systems produced gel structures some eight to 10 times weaker than the equivalent acidified systems. In all cases the caprine systems were weaker than the bovine gels despite having higher protein contents. In all cases the ‘ropy’ milk systems followed somewhat different gelation patterns and formed weaker gels than the equivalent ‘non‐ropy’ and GDL‐acidified systems. These data suggested that the starter culture material (biomass and extracellular polysaccharides) may have interfered with the protein–protein interactions during yogurt fermentation. This produced weaker gel structures, possibly by a modified gelation mechanism.

Bovine and caprine yogurt gels made using ‘ropy’ (extracellular polysaccharide‐producing starters) and ‘non‐ropy’ starter cultures were examined using dynamic (oscillatory) testing. The storage (G¸) and loss (G˝) moduli of the ropy gels were found to be lower than those of the equivalent non‐ropy ones. Both moduli of the ropy gels declined on storage (at 4°C). On the other hand, the loss tangents of the gels made using the ropy starters were higher than those of the non‐ropy gel systems. Caprine yogurt gels were some eight times weaker than the equivalent bovine systems, the ropy gels again being weaker that the non‐ropy systems. These data suggest that the secreted polysaccharide may well interfere with the gel structure and development.

Non-destructive dynamic oscillatory testing using a controlled stress rheometer (CSR) was carried out on wheat flour doughs. The doughs were mixed (and tested destructively) using the traditional farinograph method. The rheology of doughs mixed for different times and doughs prepared with potassium bromate were compared using both instruments. Doughs mixed for 2 and 30 min on the farinograph were shown to have similar ‘consistency’ when tested by the CSR, whereas the farinogram taken during mixing suggested that the structure of the doughs mixed for 30 min had been destroyed. Non-destructive testing of the doughs subjected to mixing for 30 min unexpectedly showed greater variation than doughs mixed for 2 min.

The effect of the addition of potassium bromate (KBrO3) on the rheological properties of wheat flour dough were studied using a controlled stress rheometer (CSR). Differences in the storage modulus (G′) were observed when a range of frequencies and torque measurements were used between dough samples containing 50 ppm KBrO3 and their corresponding controls. It was not possible to observe such differences using the conventional farinograph techniques.

An in vitro model was developed to assess particle deposition from aerosol formulations. The model consisted of a glass “mouth” and “trachea”, the latter being bifurcated at the lower end. These were designed to reproduce the anatomical dimensions of an average healthy human airway. One of the bifurcated ‘primary bronchi’ was connected to a multi-stage cascade impactor and the other to a vacuum pump. Air was drawn independently through these branches at 28.3 1 · min−1 giving a combined air flow at the ‘mouthpiece’ of 56.6 1 · min−1. This accomodated the operating flow rate of the impactor and simulates an inspiration rate typical of asthmatic patients. The model was completely enclosed in an environmental chamber in which temperature could be controlled at 37 ° C. Air was drawn through the model from a second chamber, also heated to 37 ° C, or taken from a humidifying chamber when the air was counterflowed over a heated water area of 1 m2. The deposition of salbutamol as base or sulphate from a metered pressurised inhaler (MDI) and a dry powder inhaler (DPI), respectively, was examined at relative humidities of 30% and 97.5%. The percentage of the deposited dose from the MDI and DPI within the potential therapeutically active size range decreased significantly (P < 0.02) from 45.4 and 25.4 to 38.0 and 18.0, respectively as the humidity was increased from 30% to 97.5%.

Journal Article A Realistic Approach to Optical Methods of Ciliary Beat Frequency Measurement Get access A E Bell, A E Bell Department of Pharmacy, Brighton Polytechnic, Brighton, UK Search for other works by this author on: Oxford Academic Google Scholar C Marriott, C Marriott Department of Pharmacy, Brighton Polytechnic, Brighton, UK Search for other works by this author on: Oxford Academic Google Scholar I P Tansey I P Tansey Riker Laboratories, Loughborough, UK Search for other works by this author on: Oxford Academic Google Scholar Journal of Pharmacy and Pharmacology, Volume 34, Issue Supplement_12, December 1982, Page 92P, https://doi.org/10.1111/j.2042-7158.1982.tb00923.x Published: 12 April 2011

The chapter explains how field electron microscopy has established itself as a powerful tool for elucidating a variety of phenomena occurring at metal and semiconductor surfaces. The quasielectron momentum components perpendicular to the tunneling direction are conserved during electron tunneling through a finite potential barrier. The chapter talks about the many-body approach that involves the thermodynamic Green's function method to treat field emission from superconductors, and nonideal metals in which electrons collide with phonons, impurities, and lattice imperfections. The method was also applied to the effect of a finite analyzer resolution. The atomic potential was represented both by a square well with an attractive core parameterized by its depth and width, and by a repulsive delta function potential that was equivalent to orthogonalization of the tunneling electron wavefunction to the occupied, tightly bound adsorbate electron orbitals. Plausible forms for the pseudopotential for both metallic and neutral adsorbates were suggested. The chapter also states that a Stark splitting of an electron–phonon transition can be envisioned in the case of degenerate vibrational, rotational, or bending modes.

A study has been made of the promoted field desorption of the adsorbates H 2 , CH 4 and Xe by He and of H 2 and CH 4 by Ar. In each case, the presence of the gas significantly lowers the desorption evaporation field of the adsorbate; in the presence of He, the fields for onset of field desorption of H 2 , CH 4 and Xe converge to 3.0 V A ̊ . Promoted field desorption is discussed in terms of energy transfer to the adsorbate by gas atom impact and by electronic excitation which is thought to be the dominant mechanism. A third mechanism involving formation of heteronuclear complexes of the type HeXe + is not ruled out.