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R Miller

Publications and source records attributed to R Miller.

At least 55 records · Page 3Linked to original sources
PubMed2004

Dynamic surface properties of poly(N-isopropylacrylamide) solutions.

The dynamic surface elasticity of aqueous solutions of poly(N-isopropylacrylamide) (pNIPAM) has been measured by the oscillating barrier and capillary wave methods as a function of time and concentration. While the real and imaginary parts of the surface elasticity almost did not change with the concentration, their kinetic dependencies proved to be nonmonotonic. Simultaneous measurements of the film thickness and adsorbed amount by null-ellipsometry showed that the pNIPAM adsorption can be divided into two steps corresponding to the formation of a concentrated narrow region close to the air phase and a region of tails and loops protruding into the bulk liquid. The local maximum of the elasticity can be observed in the course of the first step when the adsorbed macromolecules do not form long loops and tails. The results are in agreement with recent data on the nonequilibrium surface properties of solutions of other nonionic homopolymers and the theory of dilational surface viscoelasticity.

Journal Article↗
PubMed2004

IL-15 is superior to IL-2 in the generation of long-lived antigen specific memory CD4 and CD8 T cells in rhesus macaques.

Using tetanus toxoid (TT) and influenza (Flu) immunization of rhesus macaques as a model, the effect of IL-2 and IL-15 on the generation and maintenance of antigen specific memory T cells was evaluated following primary and secondary immunization. Daily cytokine administration expanded primarily effector but not memory cells, while spacing cytokine administration to q3-7 days markedly enhanced TT and Flu specific memory responses. Following primary immunization, TT specific CD4 and influenza matrix protein (Flu-MP) specific CD8 effector responses were enhanced by IL-2 administration but CD8 specific memory responses were no different from cytokine non-treated monkeys. In contrast, expansion of Flu specific CD8 cells with IL-15 was only modest but resulted in significantly elevated levels of memory cells at 6 months. IL-15 also significantly enhanced early and late TT specific CD4 responses. The highest levels of primary effector and memory T cells were observed following alternate administration of both IL-2 and IL-15. Following booster immunization, however, only IL-15 appeared able to enhance CD8 T cell responses while IL-2 or IL2/IL-15 administration were less effective.

Adjuvants, Immunologic↗
PubMed2004

Determination of protein adsorption by comparative drop and bubble profile analysis tensiometry.

Proteins adsorb at a liquid interface at very low bulk concentrations which is significantly decreased due to the adsorbed amount. Depending on the surface area A to solution bulk volume V ratio this loss in protein can be significant. Using experimental methods with large differences in the A/V ratio the adsorbed amount can be determined from the measured quantities, for example the surface tension. For beta-casein and bovine and human serum albumin data from literature obtained by the Wilhelmy technique and own data measured by drop profile analysis tensiometry are used. The adsorbed amounts measured directly from ellipsometry agree very well with those determined by the proposed method.

Adsorption↗
PubMed2004

Interfacial tensiometry as a novel methodology for the determination of surfactant adsorption at a liquid surface.

At low surfactant concentration the loss of molecules in the bulk phase due to adsorption can be significant if the surface-area-to-bulk-volume ratio is large. This loss of molecules, however, can be used to determine the adsorption of a surfactant if the experiments are performed under well-controlled conditions. Experiments are performed with the model surfactant tridecyldimethylphosphine oxide (C13DMPO) using drop profile analysis and ring tensiometry. Taking into account the different area/volume ratios and the measured equilibrium surface tensions as a measure of the final surfactant bulk concentration, the adsorption of C13DMPO is determined.

Journal Article↗
PubMed2004

Competitive adsorption from mixed nonionic surfactant/protein solutions.

A thermodynamic model is derived which is suitable to describe adsorption from a mixed protein/surfactant solution. The comparison with experimental data for HSA mixed with the nonionic surfactant decyl dimethyl phosphine oxide shows good agreement. Some model calculations are discussed in terms of the competitive character of the process of adsorption from mixed protein/surfactant solutions. The behavior of globular (HSA) and flexible (beta-casein) proteins appears to be quite different due to the possibility of changing the molar area of adsorbed protein molecules.

Adsorption↗
PubMed2004

Maximum bubble pressure tensiometry--an analysis of experimental constraints.

The maximum bubble pressure tensiometry is the only technique that allows measurements of dynamic surface tensions of surfactant solutions in the short time range down to milliseconds and even below. To reach such extremely short adsorption times, many hydrodynamic and aerodynamic effects have to be taken into consideration in order to measure physical values or to correct for the respective influences. In particular, the design of the instruments, and essentially the geometry of the measuring cell and capillary, are of key importance for accurate experiments. Another important issue is the way of determination of the characteristic bubble times, such as bubble dead time and lifetime. Examples demonstrate that the bubble pressure technique provides a powerful tool for studies of adsorption dynamics even for solutions of higher viscosities.

Journal Article↗
PubMed2004

Adsorption and surface rheology of n-dodecanol at the water/air interface.

Adsorption layers of n-dodecanol at the water/air interface show phase transitions at low temperatures [Vollhardt, Fainerman, Emrich, J. Phys. Chem. B 104 (2000) 8536]. Using a drop shape technique it is shown that the dilational elasticity disappears in the coexistence region of the adsorption layer. The relaxation time between the condensed and liquid-like surface states is in the sub-second time range.

Adsorption↗
PubMed2004

Deterministic generation of single photons from one atom trapped in a cavity.

A single cesium atom trapped within the mode of an optical cavity is used to generate single photons on demand. The photon wave packets are emitted as a Gaussian beam with temporal profile and repetition rate controlled by external driving fields. Each generation attempt is inferred to succeed with a probability near unity, whereas the efficiency for creating an unpolarized photon in the total cavity output is 0.69 +/- 0.10, as limited by passive cavity losses. An average of 1.4 x 10(4) photons are produced by each trapped atom. These results constitute an important step in quantum information science, for example, toward the realization of distributed quantum networking.

Journal Article↗
PubMed2004

Interpretation of surface dilational elasticity data based on an intrinsic two-dimensional interfacial compressibility model.

The present analysis shows that the introduction of intrinsic two-dimensional compressibility of a surfactant adsorption layer allows a much better interpretation of experimental data on the limiting (high-frequency) elasticity and characteristic frequency of diffusional relaxation than models using Frumkin's or other adsorption isotherms. The proposed model describes experimental data on surface dilational elasticity, as well as on surface pressure, sufficiently well at low and high surfactant concentrations, assuming the Lucassen and van den Tempel model of surface dilational elasticity is realized.

Journal Article↗
PubMed2004

Dynamic surface tension and adsorption kinetics of beta-casein at the solution/air interface.

A diffusion model is proposed to describe the adsorption kinetics of proteins at a liquid interface. The model is based on the simultaneous solution of the Ward-Tordai equation and a set of recently developed equations describing the equilibrium state of the adsorption layer: the adsorption isotherm, the surface layer equation of state, and the function of adsorption distribution over the states with different molar areas. The new kinetics model is compared with dynamic surface tensions of beta-casein solutions measured with the drop/bubble profile and maximum bubble pressure methods. The adsorption process for low concentrations is governed by the diffusion mechanism, while at large protein concentrations this is only the case in the initial stage. The effective diffusion coefficients agree fairly well with literature data. The adsorption values calculated from the dynamic surface tension data agree very well with the used equilibrium adsorption model.

Journal Article↗
PubMed2004

Increased expression of minichromosome maintenance protein 2 in active inflammatory bowel disease.

OBJECTIVE: Minichromosome maintenance protein 2 (Mcm2) is an accurate indicator of cell cycle entry in tissue samples, but its expression in inflammatory bowel disease (IBD) has not previously been investigated. We have used immunohistochemistry to assess the expression of Mcm2, in comparison to the existing proliferation marker Ki-67, in active IBD and IBD without inflammatory activity. MATERIALS AND METHODS: For this experimental study, sections from colonic biopsy and resection specimens of 48 patients with IBD (5 inactive/quiescent Crohn's disease (CD), 13 active CD, 19 inactive/quiescent ulcerative colitis (UC) and 11 active UC) and 15 normal controls were immunostained with antibodies to Mcm2 and Ki-67. The percentage of immunopositive epithelial nuclei was determined by calculating a labelling index (LI) for entire glands and for gland thirds (superficial, middle and basal). RESULTS: The Mcm2 LI was significantly increased in the superficial third of glands in active vs. inactive/quiescent UC (P < 0.0001) and active vs. inactive/quiescent CD (P = 0.001). The Mcm2 LI was significantly greater than the Ki-67 LI in active IBD, both in entire glands (P < 0.0001) and in the superficial third of glands (UC, P = 0.001; CD, P = 0.0002). Mcm2 LIs for entire glands were significantly higher in UC (all cases) compared to CD (all cases) (P = 0.032). CONCLUSIONS: There is increased cell cycle entry, as indicated by expression of Mcm2 and to a lesser extent Ki-67, in the superficial third of colonic glands in active IBD compared to inactive/quiescent IBD. Detection of Mcm2 may contribute to improved histological assessment of small tissue biopsies and may enable the development of a direct stool-based test for detection of active IBD and potentially for assessment of disease activity.

Cell Cycle Proteins↗
PubMed2004

Herpes simplex virus infection of the central nervous system in human immunodeficiency virus-type 1-infected patients.

We report clinical, radiological and virological data from nine consecutive HIV-infected patients with herpes simplex virus (HSV) infection of the central nervous system (CNS). Three patients presented with confusion, two with fever and headache, two with anxiety and depression, one with slow mentation and memory loss and one with expressive dysphasia. Five patients had previous AIDS-defining diagnoses: four of these five patients had previous cutaneous HSV infection. HSV DNA was detected by the polymerase chain reaction (PCR) on cerebrospinal fluid (CSF) in seven patients. HSV infection was diagnosed by brain biopsy (after negative PCR on CSF) in one patient and at autopsy in one patient (after negative CSF PCR and brain biopsy). Seven patients received specific anti-viral therapy; two died of unrelated causes and the other five recovered. Two patients were not treated, in one the diagnosis was made at autopsy and the other recovered spontaneously. HIV-infected patients with CNS HSV infection have a varied presentation. Diagnosis by PCR on CSF identified the majority of cases. With specific treatment the outcome was good.

Adult↗
PubMed2004

The use of KIT and tryptase expression patterns as prognostic tools for canine cutaneous mast cell tumors.

Cutaneous mast cell tumors (MCTs) are one of the most common tumors in dogs. Currently, prognostic and therapeutic determinations for MCTs are primarily based on the histologic grade of the tumor, but a vast majority of MCTs are of an intermediate grade, and the prognostic relevance is highly questioned. A more detailed prognostic evaluation, especially of grade 2 canine MCTs, is greatly needed. To evaluate the prognostic significance of KIT and tryptase expression patterns in canine cutaneous MCTs, we studied 100 cutaneous MCTs from 100 dogs that had been treated with surgery only. The total survival and disease-free survival time and the time to local or distant recurrence of MCTs were recorded for all dogs. Using immunohistochemistry, 98 of these MCTs were stained with anti-KIT and antitryptase antibodies. Three KIT- and three tryptase-staining patterns were identified. The KIT-staining patterns were identified as 1) membrane-associated staining, 2) focal to stippled cytoplasmic staining with decreased membrane-associated staining, and 3) diffuse cytoplasmic staining. The tryptase-staining patterns were identified as 1) diffuse cytoplasmic staining, 2) stippled cytoplasmic staining, and 3) little to no cytoplasmic staining. Based on univariate and multivariate survival analysis, increased cytoplasmic KIT staining was significantly associated with an increased rate of local recurrence and a decreased survival rate. The tryptase-staining patterns were not significantly associated with any survival parameter. On the basis of these results, we propose a new prognostic classification of canine cutaneous MCTs, according to their KIT-staining pattern, that can be used for the routine prognostic evaluation of canine cutaneous MCTs.

Animals↗