Stored Gelatinized Waxy Potato Starch Forms a Strong Retrograded Gel at Low pH with the Formation of Intermolecular Double Helices.

Waxy potato amylopectin has longer internal and external linear chains than rice or corn amylopectin that are capable of retrograding to a higher degree, but its molecular recrystallization is impeded by unprotonated phosphate groups. Here, we studied whether retrogradation and gel properties of waxy potato starch can be enhanced by lowering pH. The gel strength of waxy potato starch was strongly inversely correlated with pH, going from 10 to 4, and its magnitude was higher at pH values in which the ζ potential of the system was low. Waxy potato starch formed a strong aggregate gel driven by the formation of intermolecular double helices (G' drop25-95 °C ≈ 1358 Pa, melting ΔH = 9.5 J/g) when conditions that reduce electrostatic repulsion (pH 4, ζ = -1.7) are used, a phenomenon that was not observed in low-phosphorylated waxy cereal starches (i.e., waxy rice and corn).

Polymer nanoparticle hydrogels with autonomous affinity switching for the protection of proteins from thermal stress.

We report a new material design concept for synthetic, thermally responsive poly(N-isopropylacrylamide)-based copolymer nanoparticle (NP) hydrogels, which protect proteins from thermal stress. The NP hydrogels bind and protect a target enzyme from irreversible activity loss upon exposure to heat but "autonomously" release the enzyme upon subsequent cooling of the solution. Incorporation of the optimized amount of negatively charged and hydrophobic comonomers to the NP hydrogels was key to achieve these desired functions. As the NP hydrogels do not show a strong affinity for the enzyme at room temperature, they can remain in solution without adversely affecting enzymatic activity or they can be removed by filtration to leave the enzyme in solution. The results demonstrate the promise of this approach for improving the thermal tolerance of proteins.

Breast cancer development in transsexual subjects receiving cross-sex hormone treatment.

INTRODUCTION: Transsexual people receive cross-sex hormones as part of their treatment, potentially inducing hormone-sensitive malignancies. AIM: To examine the occurrence of breast cancer in a large cohort of Dutch male and female transsexual persons, also evaluating whether the epidemiology accords with the natal sex or the new sex. MAIN OUTCOME MEASURE: Number of people with breast cancer between 1975 and 2011. METHODS: We researched the occurrence of breast cancer among transsexual persons 18-80 years with an exposure to cross-sex hormones between 5 to >30 years. Our study included 2,307 male-to-female (MtF) transsexual persons undergoing androgen deprivation and estrogen administration (52,370 person-years of exposure), and 795 female-to-male (FtM) subjects receiving testosterone (15,974 total years of exposure). RESULTS: Among MtF individuals one case was encountered, as well as a probable but not proven second case. The estimated rate of 4.1 per 100,000 person-years (95% confidence interval [CI]: 0.8-13.0) was lower than expected if these two cases are regarded as female breast cancer, but within expectations if viewed as male breast cancer. In FtM subjects, who were younger and had shorter exposure to cross-sex hormones compared with the MtF group, one breast cancer case occurred. This translated into a rate of 5.9 per 100,000 person-years (95% CI: 0.5-27.4), again lower than expected for female breast cancer but within expected norms for male breast cancer. CONCLUSIONS: The number of people studied and duration of hormone exposure are limited but it would appear that cross-sex hormone administration does not increase the risk of breast cancer development, in either MtF or FtM transsexual individuals. Breast carcinoma incidences in both groups are comparable to male breast cancers. Cross-sex hormone treatment of transsexual subjects does not seem to be associated with an increased risk of malignant breast development.

Pressure generated by syringes: implications for hydrodissection and injection of dense connective tissue lesions.

OBJECTIVE: Hydrodissection and high-pressure injection are important for the treatment of dense connective tissue lesions including rheumatoid nodules, Dupuytren's contracture, and trigger finger. The present study determined the optimal syringes for high-pressure injection of dense connective tissue lesions. METHODS: Different sizes (1, 3, 5, 10, 20, and 60 mL) of a mechanical syringe (reciprocating procedure device) with a luer-lock fitting were studied. Twenty operators generated maximum pressure with each mechanical syringe size, and pressure was measured in pounds per square inch (psi). Subsequently, 223 dense connective tissue lesions were injected with different sizes of syringes (1, 3, or 10 mL). Outcomes included (i) successful intralesional injection and (ii) clinical response at 2 weeks. RESULTS: Smaller syringes generated significantly more injection pressure than did larger syringes: 1 mL (363 ± 197 psi), 3 mL (177 ± 96 psi), 5 mL (73 ± 40 psi), 10 mL (53 ± 29 psi), 20 mL (32 ± 18 psi), and 60 mL (19 ± 12 psi). Similarly, smaller syringes were superior to larger syringes for intralesional injection success: 10 mL: 34% (15/44) vs. 1 mL: 100% (70/70) (p < 0.001) and 3 mL: 91% (99/109) (p < 0.001). CONCLUSION: Smaller syringes (≤ 3 mL) are superior to larger syringes (≥ 5 mL) for successful hydrodissection and high-pressure intralesional injection of dense connective tissue lesions.

Application and use of isothermal calorimetry in pharmaceutical development.

There are many steps involved in developing a drug candidate into a formulated medicine and many involve analysis of chemical interaction or physical change. Calorimetry is particularly suited to such analyses as it offers the capacity to observe and quantify both chemical and physical changes in virtually any sample. Differential scanning calorimetry (DSC) is ubiquitous in pharmaceutical development, but the related technique of isothermal calorimetry (IC) is complementary and can be used to investigate a range of processes not amenable to analysis by DSC. Typically, IC is used for longer-term stability indicating or excipient compatibility assays because both the temperature and relative humidity (RH) in the sample ampoule can be controlled. However, instrument design and configuration, such as titration, gas perfusion or ampoule-breaking (solution) calorimetry, allow quantification of more specific values, such as binding enthalpies, heats of solution and quantification of amorphous content. As ever, instrument selection, experiment design and sample preparation are critical to ensuring the relevance of any data recorded. This article reviews the use of isothermal, titration, gas-perfusion and solution calorimetry in the context of pharmaceutical development, with a focus on instrument and experimental design factors, highlighted with examples from the recent literature.

A long-term follow-up study of mortality in transsexuals receiving treatment with cross-sex hormones.

OBJECTIVE: Adverse effects of long-term cross-sex hormone administration to transsexuals are not well documented. We assessed mortality rates in transsexual subjects receiving long-term cross-sex hormones. DESIGN: A cohort study with a median follow-up of 18.5 years at a university gender clinic. Methods Mortality data and the standardized mortality rate were compared with the general population in 966 male-to-female (MtF) and 365 female-to-male (FtM) transsexuals, who started cross-sex hormones before July 1, 1997. Follow-up was at least 1 year. MtF transsexuals received treatment with different high-dose estrogen regimens and cyproterone acetate 100 mg/day. FtM transsexuals received parenteral/oral testosterone esters or testosterone gel. After surgical sex reassignment, hormonal treatment was continued with lower doses. RESULTS: In the MtF group, total mortality was 51% higher than in the general population, mainly from increased mortality rates due to suicide, acquired immunodeficiency syndrome, cardiovascular disease, drug abuse, and unknown cause. No increase was observed in total cancer mortality, but lung and hematological cancer mortality rates were elevated. Current, but not past ethinyl estradiol use was associated with an independent threefold increased risk of cardiovascular death. In FtM transsexuals, total mortality and cause-specific mortality were not significantly different from those of the general population. CONCLUSIONS: The increased mortality in hormone-treated MtF transsexuals was mainly due to non-hormone-related causes, but ethinyl estradiol may increase the risk of cardiovascular death. In the FtM transsexuals, use of testosterone in doses used for hypogonadal men seemed safe.

Quantitative analysis of solid-state processes studied with isothermal microcalorimetry.

Quantitative analysis of solid-state processes from isothermal microcalorimetric data is straightforward if data for the total process have been recorded and problematic (in the more likely case) when they have not. Data are usually plotted as a function of fraction reacted (α); for calorimetric data, this requires knowledge of the total heat change (Q) upon completion of the process. Determination of Q is difficult in cases where the process is fast (initial data missing) or slow (final data missing). Here we introduce several mathematical methods that allow the direct calculation of Q by selection of data points when only partial data are present, based on analysis with the Pérez-Maqueda model. All methods in addition allow direct determination of the reaction mechanism descriptors m and n and from this the rate constant, k. The validity of the methods is tested with the use of simulated calorimetric data, and we introduce a graphical method for generating solid-state power-time data. The methods are then applied to the crystallization of indomethacin from a glass. All methods correctly recovered the total reaction enthalpy (16.6 J) and suggested that the crystallization followed an Avrami model. The rate constants for crystallization were determined to be 3.98 × 10(-6), 4.13 × 10(-6), and 3.98 × 10(-6) s(-1) with methods 1, 2, and 3, respectively.

HIV infection and associated risk factors among long-distance truck drivers travelling through Azerbaijan.

The aim of this study was to assess HIV prevalence and associated risk behaviours among international truck drivers (TDs) in Azerbaijan. The subjects signed consent and completed a questionnaire. Blood was tested using two rapid HIV tests: Determine and OraQuick. Genotyping was performed on 13 positives. Overall, 3763 TDs from 21 countries were enrolled. Fifty-eight (1.54%) were HIV-positive. Highest prevalence was among Russians (2.88%), Ukrainians (1.66%) and Azerbaijani (1.09%). On univariate analysis, highest prevalence (60%) was among injecting drug users (IDUs) compared with 0.4% among non-IDUs (P < 0.001). The prevalence in men who had sex with men (MSM) (42.9%) was high (P

Evaluation of an educational intervention for farming families to protect their children from pesticide exposure.

A culturally appropriate educational intervention was developed and directed towards farming families in Menoufia governorate, Egypt, to improve their knowledge and practices in protecting their children from exposure to pesticides. Parents were randomly assigned to either a lecture or videotape training group. Ability to recall information or improve practices among parents was evaluated in 3 sessions: pretraining and 2 weeks and 1 month after training. Knowledge and practice scores after training of younger and more educated participants were significantly higher than older, less educated participants. Knowledge and practice performance of the videotape group was better than the lecture group and in both groups the improvement of knowledge scores after training was significantly higher than that of practice scores.

Evaluation of an educational intervention for farming families to protect their children from pesticide exposure

A culturally appropriate educational intervention was developed and directed towards farming families in Menoufia governorate, Egypt, to improve their knowledge and practices in protecting their children from exposure to pesticides. Parents were randomly assigned to either a lecture or videotape training group. Ability to recall information or improve practices among parents was evaluated in 3 sessions: pretraining and 2 weeks and 1 month after training. Knowledge and practice scores after training of younger and more educated participants were significantly higher than older, less educated participants. Knowledge and practice performance of the videotape group was better than the lecture group and in both groups the improvement of knowledge scores after training was significantly higher than that of practice scores

Development of an isothermal heat-conduction photocalorimeter.

Assessing photostability (particularly of pharmaceuticals) is of growing importance, but hampered by a lack of reliable, rapid experimental testing protocols and instrumentation. In particular, most approaches require irradiation of the sample separately from the analytical measurement, which increases both experimental complexity and the number of assumptions that must be made when calculating stability. One technique that may obviate this is photocalorimetry, principally because the reporter of change (heat) is measured directly as a sample is irradiated. Although not a new idea, the design challenges of photocalorimeters are complex, primarily because light power is being introduced to the calorimeter which can thus both saturate the amplifiers and swamp the response of the sample. Careful instrument design is thus paramount. The aim of this work was to develop a robust, compact, and easy to use photocalorimeter with the immediate focus of developing photostability assays for pharmaceuticals. The final instrument design, arrived at through a series of iterative design modifications, is based on a twin differential heat-conduction principle and achieves an average base line deflection of -0.04+/-0.11 microW with light irradiating the sample cell. The performance capabilities of the instrument were demonstrated using a model system; the photodegradation of 2-nitrobenzaldehyde in solution.

Application of chemometric analysis to complexity in isothermal calorimetric data.

The interpretation of complexity in isothermal calorimetric data is demanding. The observed power signal is a composite of the powers arising from each of the individual events occurring (which can involve physical, as well as chemical, change). The challenge, therefore, lies in deconvoluting the observed data into their component parts. Here, we discuss the potential use of chemometric analysis, because it offers the significant advantage of being model-free, using principal component analysis to deconvolute data. Using model data, we discovered that the software required a minimum trivariate data matrix to be constructed. Two variables, power and time, were available from the raw data. Selection of a third variable was more problematic, but it was found that by running multiple experiments the small variation in the number of moles of compound in each experiment was sufficient to allow a successful analysis. In general we noted that it required a minimum 2n + 2 repeat experiments to allow analysis (where n is the number of reaction processes). The data outputted from the chemometric software were of the form intensity (arbitrary units) versus time, reflecting the fact that the software was written for analysis of spectroscopic data. We provide a mathematical treatment of the data that allows recovery of both reaction enthalpy and rate constants. The study demonstrates that chemometric analysis is a promising approach for the interpretation of complex calorimetric data.

A comparison of chemical reference materials for solution calorimeters.

Solution calorimeters are based on semi-adiabatic or isothermal heat-conduction principles and differ in the way they record data. They also have different measuring sensitivities and require different quantities of solute and solvent. As such, the choice of chemical test substance is not straightforward. Usually the dilution of KCl is recommended; it is possible to purchase a reference sample of KCl that has a certified enthalpy of solution and this standard material is usually used to test semi-adiabatic instruments. Here, we review the suitability of a range of chemical test substances (KCl, sucrose and Tris) for an isothermal heat-conduction solution calorimeter. It was found that KCl was not the best test material because its relatively high enthalpy of solution (DeltasolH) necessitated the use of small samples (2 mg), resulting in a relatively large standard deviation (sigman-1) in the values recorded (DeltasolH=17.14+/-0.49 kJ mol-1); furthermore, KCl data must be corrected to account for the effect of dilution, although the correction was found to be small (0.07 kJ mol-1) under the experimental conditions employed here. Sucrose appears to be a much more robust test material for isothermal heat-conduction instruments because its lower enthalpy of solution allows the use of much larger samples (20 mg), which minimises experimental errors. The DeltasolH value returned (6.14+/-0.08 kJ mol-1) is in excellent agreement with the literature. It is also cheap, readily available and requires minimal preparation although its widespread use would require the preparation of a certified reference sample.

Crystal structure of the flagellar rotor protein FliN from Thermotoga maritima.

FliN is a component of the bacterial flagellum that is present at levels of more than 100 copies and forms the bulk of the C ring, a drum-shaped structure at the inner end of the basal body. FliN interacts with FliG and FliM to form the rotor-mounted switch complex that controls clockwise-counterclockwise switching of the motor. In addition to its functions in motor rotation and switching, FliN is thought to have a role in the export of proteins that form the exterior structures of the flagellum (the rod, hook, and filament). Here, we describe the crystal structure of most of the FliN protein of Thermotoga maritima. FliN is a tightly intertwined dimer composed mostly of beta sheet. Several well-conserved hydrophobic residues form a nonpolar patch on the surface of the molecule. A mutation in the hydrophobic patch affected both flagellar assembly and switching, showing that this surface feature is important for FliN function. The association state of FliN in solution was studied by analytical ultracentrifugation, which provided clues to the higher-level organization of the protein. T. maritima FliN is primarily a dimer in solution, and T. maritima FliN and FliM together form a stable FliM(1)-FliN(4) complex. Escherichia coli FliN forms a stable tetramer in solution. The arrangement of FliN subunits in the tetramer was modeled by reference to the crystal structure of tetrameric HrcQB(C), a related protein that functions in virulence factor secretion in Pseudomonas syringae. The modeled tetramer is elongated, with approximate dimensions of 110 by 40 by 35 Angstroms, and it has a large hydrophobic cleft formed from the hydrophobic patches on the dimers. On the basis of the present data and available electron microscopic images, we propose a model for the organization of FliN subunits in the C ring.

Interaction of phloretin and 6-ketocholestanol with DPPC-liposomes as phospholipid model membranes.

Phloretin and 6-ketocholestanol are penetration enhancers for percutaneous delivery of certain topically applied drugs. In the present study some physicochemical experiments have been performed to elucidate the mechanism of action of phloretin and 6-ketocholestanol. The penetration enhancing effect of phloretin and 6-ketocholestanol is believed to be due to their increase of the fluidity of the intercellular lipid bilayers of the stratum corneum. Phospholipid vesicles were chosen as a simple model to represent these bilayers. The effect of phloretin and 6-ketocholestanol on phase transition temperature and enthalpy was studied using differential scanning calorimetry. Beside of that the size of liposomes was monitored when the amount of penetration enhancer in the liposome preparation was changed. Addition of increasing amounts of phloretin and 6-ketocholestanol to the bilayer resulted in lowering of phase transition temperatures and increasing the enthalpy. Additionally the size of the liposomes was increased when penetration enhancer was added. The results suggest that phloretin as well as 6-ketocholestanol would interact with stratum corneum lipids in a similar manner, both reduce the diffusional resistance of the stratum corneum to drugs with balanced hydrophilic-lipophilic characteristics.

Stability assessment of pharmaceuticals by isothermal calorimetry: two component systems.

Isothermal calorimetry offers the potential to determine rapidly the stability of formulated pharmaceuticals because it is indifferent to physical form and sensitive enough to detect extremely small powers; ca. 50 nW at 25 degrees C. However, its use in this area is not widespread, principally because the power-time data obtained often comprise contributions from more than one process and are thus difficult to analyse quantitatively. In this work, we demonstrate how power-time data recorded for systems in which two components are degrading in parallel (in this case, binary mixtures of selected parabens) can be analysed using a kinetic-based model; the methodology allows the determination of the first-order rate constant and reaction enthalpy for each process, so long as one rate constant is at least twice the magnitude of the other. It was found that the reactions did not need to run to completion in order for the analysis to be successful; a minimum of 15 min of data were required for samples with one degrading component and a minimum of 4 h of data were required for samples with two degrading components. It was observed that the rate constants for paraben degradation in binary systems were significantly lower than expected. This was ascribed to the fact that the parabens degrade to a common product and is an important factor that should be accounted for when the two or more parabens are formulated together.

Antimicrobial properties of silver-containing wound dressings: a microcalorimetric study.

The studies reported here have been undertaken to assess the potential use of isothermal microcalorimetry in studying the antimicrobial efficacy of wound dressings that contain antimicrobial agents. The microcalorimetric technique allows non-invasive and non-destructive analysis to be performed directly on a test sample, regardless of whether it is homogeneous or heterogeneous in nature. Microcalorimetry is an established procedure that offers quantitative measurements and has the distinct advantage over traditional antimicrobial test methodologies in that calorimetric measurements are made continuously over real-time, thus the dynamic response of microorganisms to an antimicrobial agent is observed in situ. The results described in this paper are for interaction of two silver-containing wound care products AQUACEL Ag Hydrofiber (ConvaTec, Deeside, UK) and Acticoat 7 with SILCRYST (Smith and Nephew Healthcare, UK) with the wound pathogenic organisms Staphylococcus aureus and Pseudomonas aeruginosa. Both dressings are shown, microcalorimetrically, to have the capacity to kill these common wound pathogens within 1-2 h of contact. A dose-response study was conducted with the AQUACEL Ag dressing. Microcalorimetry is shown to be rapid, simple and effective in the study of the antimicrobial properties of gel forming wound dressings.

Is primary haemostasis controlled by a 'platelet delay time'? Formulation of a new hypothesis.

A simple physical model is able to adequately describe platelet thrombus formation during primary haemostasis ex vivo, under the assumption of a 'platelet delay time' (Pdel), which is defined as the difference between the moment of platelet adhesion (to collagen or to another adherent platelet) and the time when the newly adherent platelet allows another platelet to adhere. Pdel was estimated with an ex vivo model of primary haemostasis (modified PFA-100, Dade Behring, Marburg). ADP and epinephrine test cartridges were perfused with human anticoagulated blood of control persons using a pressure/flow clamp technique (Kretschmer V, et al. Platelets 2001; 12: 462-9). Platelets gradually occluded the aperture in the test system. Pressure (p) across and flow (Q) through the aperture were measured versus time. The change of the aperture radius versus time (dr/dt) was calculated from p and Q using the Law of Hagen-Poiseuille. The surprising result was a constant decay of dr/dt (Rsqu approximately 0.996), in spite of a 5-fold increase in the shear- and transport-rates of platelets. This can be explained by postulating the existence of a Pdel, which was estimated as 2.89 s for collagen/ADP and 4.62 s in collagen/epinephrine test cartridges. This new hypothesis explains for the first time the relative independence of in vivo and ex vivo bleeding time on blood platelet concentrations, a well known observation at platelet counts higher than 40,000/microl. If the described physical model is correct, platelet thrombus growth rate is strongly decreased as a consequence of Pdel in extreme arterial flow conditions. A preliminary report of these experiments has been published (Kratzer MAA, Platelets 2002; 13: 344).

Disease concepts and treatment practices relating to schistosomiasis haematobium in Upper Egypt.

Disease concepts and medical treatment practices surrounding schistosomiasis haematobium were studied among males in Upper Egyptian villages and towns using interview methods. Most informants considered bilharzia to be a serious disease for which they commonly sought treatment. Its occurrence was attributed primarily to natural causes, particularly various aquatic worms and insects, dirts, excrement, dead animals, toxins and stagnant and vegetated waters, mostly large canals. Contact with water from the Nile river was generally thought to be quite safe. Drug treatment was weakly associated with amount of education. All groups reported use of antischistosomal drugs and plant medicines. Seventy-four per cent of the sample had a treatment history, 64% having taken oral drugs and/or injections, 40% plant medicines and 29% both. Drinking decoctions of damsissa (Ambrosia maritima) was the most commonly used household remedy. Plant materials were usually obtained from fields, gardens and local markets and patent medicines from nearby clinics and private physicians in towns. Recommendations are made for the national mass chemotherapy programme.