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PubMed2005

Parent-child interaction using a mobile and wireless system for blood glucose monitoring.

BACKGROUND: Children with type 1 diabetes and their parents face rigorous procedures for blood glucose monitoring and regulation. Mobile telecommunication systems show potential as an aid for families' self-management of diabetes. OBJECTIVE: A prototype designed to automatically transfer readings from a child's blood glucose monitor to their parent's mobile phone was tested. In this formative stage of development, we sought insights into the appropriateness of the concept, feasibility of use, and ideas for further development and research. METHODS: During four months, a self-selected sample of 15 children (aged 9 to 15 years) with type 1 diabetes and their parents (n = 30) used the prototype approximately three times daily. Parent and child experiences were collected through questionnaires and through interviews with 9 of the parents. RESULTS: System use was easily integrated into everyday life, and parents valued the sense of reassurance offered by the system. Parents' ongoing struggle to balance control of their children with allowing independence was evident. For children who measured regularly, use appeared to reduce parental intrusions. For those who measured irregularly, however, parental reminders (eg, "nagging") appeared to increase. Although increased reminders could be considered a positive outcome, they can potentially increase parent-child conflict and thus also undermine proper metabolic control. Parents felt that system appropriateness tapered off with the onset of adolescence, partly due to a potential sense of surveillance from the child's perspective that could fuel oppositional behavior. Parental suggestions for further developments included similar alerts of irregular insulin dosages and automatically generated dietary and insulin dosage advice. CONCLUSIONS: User enthusiasm suggests that such systems might find a consumer market regardless of whether or not they ultimately improve health outcomes. Thus, more rigorous studies are warranted to inform guidelines for appropriate use. Potentially fruitful approaches include integrating such systems with theory-based parenting interventions and approaches that can aid in interpreting and responding to experiences of surveillance, virtual presence, and balances of power in e-mediated relationships.

Adolescent↗
PubMed2005

Interactions between the Fe(III)-reducing bacterium Geobacter sulfurreducens and arsenate, and capture of the metalloid by biogenic Fe(II).

Previous work has shown that microbial communities in As-mobilizing sediments from West Bengal were dominated by Geobacter species. Thus, the potential of Geobacter sulfurreducens to mobilize arsenic via direct enzymatic reduction and indirect mechanisms linked to Fe(III) reduction was analyzed. G. sulfurreducens was unable to conserve energy for growth via the dissimilatory reduction of As(V), although it was able to grow in medium containing fumarate as the terminal electron acceptor in the presence of 500 muM As(V). There was also no evidence of As(III) in culture supernatants, suggesting that resistance to 500 muM As(V) was not mediated by a classical arsenic resistance operon, which would rely on the intracellular reduction of As(V) and the efflux of As(III). When the cells were grown using soluble Fe(III) as an electron acceptor in the presence of As(V), the Fe(II)-bearing mineral vivianite was formed. This was accompanied by the removal of As, predominantly as As(V), from solution. Biogenic siderite (ferrous carbonate) was also able to remove As from solution. When the organism was grown using insoluble ferrihydrite as an electron acceptor, Fe(III) reduction resulted in the formation of magnetite, again accompanied by the nearly quantitative sorption of As(V). These results demonstrate that G. sulfurreducens, a model Fe(III)-reducing bacterium, did not reduce As(V) enzymatically, despite the apparent genetic potential to mediate this transformation. However, the reduction of Fe(III) led to the formation of Fe(II)-bearing phases that are able to capture arsenic species and could act as sinks for arsenic in sediments.

Arsenates↗
PubMed2006

DNA damage and L1 retrotransposition.

Barbara McClintock was the first to suggest that transposons are a source of genome instability and that genotoxic stress assisted in their mobilization. The generation of double-stranded DNA breaks (DSBs) is a severe form of genotoxic stress that threatens the integrity of the genome, activates cell cycle checkpoints, and, in some cases, causes cell death. Applying McClintock's stress hypothesis to humans, are L1 retrotransposons, the most active autonomous mobile elements in the modern day human genome, mobilized by DSBs? Here, evidence that transposable elements, particularly retrotransposons, are mobilized by genotoxic stress is reviewed. In the setting of DSB formation, L1 mobility may be affected by changes in the substrate for L1 integration, the DNA repair machinery, or the L1 element itself. The review concludes with a discussion of the potential consequences of L1 mobilization in the setting of genotoxic stress.

Journal Article↗
PubMed2000

Preclinical mobility disability predicts incident mobility disability in older women.

BACKGROUND: Physical disability and dependency are serious, and frequent, adverse health outcomes associated with aging and resulting from chronic disease. Reasoning has suggested that there might be a preclinical, intermediate phase of disablement which might develop in parallel with progression of underlying disease and precede and predict disability. Definition of this stage could provide a basis for screening and early intervention to prevent disability. The objective of this study was to determine preclinical functional predictors of incident mobility difficulty and provide evidence for a preclinical stage of disability. METHODS: A prospective, population-based cohort study was carried out in Baltimore, Maryland, with two evaluations 18 months apart. The participants were 436 community-dwelling women, 70-80 years of age at baseline, not cognitively impaired, and reporting difficulty in no areas, or only one area, of physical function (primarily mobility), who were participating in the Women's Health and Aging Study II. Participants were recruited from a population-based, age-stratified random sample. Incident mobility disability was studied in the subset without such disability at baseline. The main outcome measure was self-reported incident difficulty walking 1/2 mile or climbing up 10 steps. RESULTS: At baseline, 69.3% of the cohort reported no difficulty with mobility. After 18 months, 16.0 and 11.7% of this group reported incident difficulty walking 1/2 mile or climbing up 10 steps, respectively. Those reporting baseline task modification due to underlying health problems, our measure of preclinical disability, were at three- to fourfold higher odds of progressing to difficulty than were those without such modification. In multivariate logistic regression analyses, this self-report measure, task modification without difficulty, and objective measures of performance were independently and jointly predictive of incident mobility difficulty. Specifically, for incident difficulty walking 1/2 mile, self-reported task modification odds ratio (OR) = 3.67, walking speed (.5 m/s difference) OR = 2.16; for incident difficulty climbing up 10 stairs, OR for task modification = 3.84, for stair climb speed (1/3 step/s difference) = 2.08 (95% CI did not include 1 for any). Covariates, age, living alone, number of chronic diseases, depression score, knee strength, and balance by functional reach, were not significant predictors in either model. CONCLUSIONS: Two indicators of functional changes in older women without mobility difficulty, self-report of modification of method of doing a task in the absence of difficulty and performance measures, are independent and strong predictors of risk of incident mobility disability. The self-report measure provides substantial strength in predicting risk of incident disability across the full range of performance, and may identify a vulnerable point at which other risk factors act to cause transitions to disability. Together, the preclinical indicators identify a subset of high-functioning older women who are at high risk of mobility disability, and provide a potential basis for screening for disability risk and targeting interventions to prevent mobility disability.

Activities of Daily Living↗
PubMed2004

Arsenic and heavy metal mobility in iron oxide-amended contaminated soils as evaluated by short- and long-term leaching tests.

Several iron-bearing additives were evaluated for their effectiveness in the attenuation of arsenic (As) in various contaminated soils. These were selected for their known or potential ability to adsorb As anions, thus changing the speciation of As in a soil system. Three soils with different sources of As contamination were investigated (canal dredgings, coal fly ash deposits, and low-level alkali waste). The amendments used were goethite (alpha-FeOOH), iron grit, iron (II) and (III) sulphates (plus lime), and lime, applied to the soils at a rate of 1% w/w. A series of leachate extraction tests (UKEA, ASTM and modified Dutch column leaching test) were conducted on the equilibrated amended soils. These were used to firstly evaluate the potential of the amendments as immobilising agents, and secondly to compare the short- and long-term durability of their effects. Column tests demonstrated the efficiency of iron oxides over the longer time scale; these treatments significantly reduced concentrations of arsenic in leachates from all treated soils. Amended soils were also observed to contain higher levels of lead (Pb) and cadmium (Cd) in their leachates, signifying that certain Fe-oxides potentially increased heavy metal mobility in treated soils. The conclusions were that whilst Fe-oxides may be used as effective in situ amendments to attenuate As in soils, their effects on other trace elements, such as Pb and Cd, require careful consideration.

Adsorption↗
PubMed1987

Potentiation by glucose metabolites of inositol trisphosphate-induced calcium mobilization in permeabilized rat pancreatic islets.

Saponin-permeabilized rat pancreatic islets degraded exogenously added inositol 1,4,5-trisphosphate (IP3), and degradation was inhibited in the presence of either fructose 1,6-bisphosphate or diphosphoglycerate. The addition of either fructose-1,6-P2 or diphosphoglycerate to 45Ca2+-labeled permeabilized islets potentiated 45Ca2+ release caused by IP3 (by either exogenously added IP3 or IP3 generated endogenously in the presence of carbachol or guanosine 5'-3-O-(thio)triphosphate (GTP gamma S). The effect of diphosphoglycerate and fructose-1,6-P2 on 45Ca2+ release correlated well with the effects of these agents on the recovery of radioactivity in IP3. These results further support our previous proposal that in pancreatic islets intracellular calcium mobilization may be sustained in part via the inhibition of IP3 degradation by metabolites produced during stimulation with insulinotropic concentrations of glucose (Rana, R.S., Sekar, M.C., Hokin, L.E., and MacDonald, M.J. (1986) J. Biol. Chem. 261, 5237-5240).

Animals↗
PubMed2001

Determination of growth hormone-releasing hexapeptide by reversed-phase high-performance liquid chromatography with electrochemical detection.

A novel HPLC method with electrochemical detection is described for the determination of a growth-hormone-releasing hexapeptide (GHRP-6). HPLC conditions, such as the column, mobile phase, and oxidation potential, were optimized for sensitivity and selectivity of analysis. GHRP-6 was separated on a reversed-phase CN column with 37% acetonitrile in 100 mM phosphate buffer (pH 7.0) as the mobile phase. The optimum electrochemical oxidation signal was obtained at 0.85 V vs. Ag/AgCl in a glassy carbon working electrode due to two electroactive tryptophans and a histidine residue. Solid-phase extraction using octadecyl cartridges was optimized for sample cleanup of GHRP-6 from serum samples and the method was successfully applied over the concentration range of 5 to 100 ng/ml of analyte. reserved.

Chromatography, High Pressure Liquid↗
PubMed2004

Conceptual and numerical model of uranium(VI) reductive immobilization in fractured subsurface sediments.

A conceptual model and numerical simulations of bacterial U(VI) reduction in fractured subsurface sediments were developed to assess the potential feasibility of biomineralization at the fracture/matrix interface as a mechanism for immobilization of uranium in structured subsurface media. The model envisions flow of anaerobic groundwater, with or without acetate as an electron donor for stimulation of U(VI) reduction by dissimilatory metal-reducing bacteria (DMRB), within mobile macropores along a one-dimensional flow path. As the groundwater moves along the flow path, U(VI) trapped in the immobile mesopore and micropore domains (the sediment matrix) becomes desorbed and transferred to the mobile macropores (fractures) via a first-order exchange mechanism. By allowing bacterial U(VI) reduction to occur in the mesopore domain (assumed to account for 12% of total sediment pore volume) according to experimentally-determined kinetic parameters and an assumed DMRB abundance of 10(7) cells per cm3 bulk sediment (equivalent to 4 mg of cells per dm3 bulk sediment), the concentration of U(VI) in the macropore domain was reduced ca. 10-fold compared to that predicted in the absence of mesopore DMRB activity after a 6-month simulation period. The results suggest that input of soluble electron donors over a period of years could lead to a major redistribution of uranium in fractured subsurface sediments, converting potentially mobile sorbed U(VI) to an insoluble reduced phase (i.e. uraninite) in the mesopore domain that is expected to be permanently immobile under sustained anaerobic conditions.

Adsorption↗
PubMed2000

Hydrodynamic and Colloidal Interactions in Concentrated Charge-Stabilized Polymer Dispersions.

Hydrodynamic and colloidal interactions are explored in concentrated, charge-stabilized colloidal dispersions by measuring the dependence of rheology (e.g., low and high-shear viscosity, high-frequency viscosity, and modulus) and self-diffusivity on salt content, particle size, and concentration. Model, sulfonated polystyrene lactices of varying diameter are prepared and investigated by shear rheology, high-frequency torsional resonance, electrophoresis, titration, and dynamic light scattering. The high-frequency and high-shear viscosity both are dominated by hydrodynamic interactions, but are shown not to be identical, due to the microstructure distortion resulting from high shear rates. The short-time self-diffusion is also shown to be insensitive to direct particle interactions, but has a different concentration dependence than the high-frequency viscosity, further illustrating a predicted violation of a generalized Stokes-Einstein relationship for these properties. The apparent colloidal surface charge is extracted from the high-frequency elastic modulus measurements on concentrated dispersions. The surface charge is in good agreement with results from critical coagulation concentration measurements and perturbation theories, but disagrees with electrophoretic mobility experiments. This indicates that the effective surface charge determined by torsional high-frequency measurements is a more reliable predicter of the salt stability of charge-stabilized dispersions, in comparison to zeta-potentials determined from electrophoretic mobilities. Further, we demonstrate by direct comparison that measurements of the apparent plateau modulus by rotational rheometry underestimate the true, high-frequency modulus and provide unreliable estimates for the surface charge. Copyright 2000 Academic Press.

Journal Article↗
PubMed1980

[Effect of 22Na on the zeta potential of malignant cells].

Membrane changes of Yoshida tumor ascites cells, "in toto" or centrifuged, were studied means of cytopherometric and istoautoradiographic techniques, by using various specific activities of 22 NaCl for different time intervals. This study shows the existence of a relationship between cellular membranes and cytoplasm labelled electrophoretic mobility and the Zeta potentials of the tumor cells. The presence of ascites liquid appears to be critical.

Animals↗
PubMed2005

Determination of high mobility group A1 (HMGA1) expression in hepatocellular carcinoma: a potential prognostic marker.

Our objective was to investigate the expression of HMGA1 mRNA and protein in hepatocellular carcinoma (HCC) and the correlation between its expression and clinical pathological characteristics and prognosis. HMGA1 expression was determined at both the mRNA level and the protein level in 30 HCC tissues and their corresponding paracancer liver tissues (PCLTs) and 2 normal liver tissues by RT-PCR and IHC. Follow-up study was done on the 30 patients involved in this research. HMGA1 mRNA was detected in nine cases of HCC tissues and two PCLTs, for a positivity rate of 30% and 6.7%, respectively (P < 0.05), whereas no HMGA1 mRNA expression was found in normal liver tissues. Clinicopathological analysis revealed that HMGA1 mRNA expression was significantly correlated with Edmondson's grade (P < 0.05). HMGA1 protein was detected in four HCC tissues by IHC and located mainly in the nuclei; no positive staining was found in PCLTs. Follow-up study showed that HMGA1 mRNA-positive patients had a higher risk of recurrence/metastasis and a shorter survival than negative cases (P < 0.05). Our findings indicate that HMGA1 may be involved in the carcinogenesis and invasiveness of HCC and the determination of HMGA1 can be of great value in predicting the prognosis of patients with HCC.

Carcinoma, Hepatocellular↗
PubMed2001

Microbial populations associated with the reduction and enhanced mobilization of arsenic in mine tailings.

Microbial reduction of arsenate [As(V)] to arsenite [As(III)] and the subsequent effects on As mobilization in contaminated mine tailings were studied under transport conditions. Molecular analysis of bacterial populations and traditional isolation techniques were used in conjunction with column experiments designed to observe relationships among pH (limed vs unlimed treatments), redox potential (Pt electrode), and mobilization of As. Liming increased pH values from approximately 4 to 8, resulting in a 5-fold increase in total As eluted from sterile columns. Elution of As from limed columns was further enhanced by microbial activity. As(III) was the predominant As species eluted from oxic, nonsterile columns. Conversely, in sterile treatments, As(V) was the predominant valence state in column effluent. Denaturing gradient gel electrophoresis coupled with sequence and phylogenetic analysis of 16S rRNA gene segments revealed that liming of the mine tailings stimulated specific Caulobacter-, Sphingomonas-, and Rhizobium-like populations. Pure culture isolates of these bacteria demonstrated the ability to rapidly reduce As(V) in aerated serum bottles. An intracellular As detoxification pathway was implicated in the reduction of As(V) by these isolates. These results indicate that microbial reduction of As(V) in As-contaminated soils may occur under aerobic conditions over relatively short time scales resulting in enhanced As mobilization.

Arsenic↗
PubMed1995

Effect of chloride ion on the sedimentation volume and zeta potential of zinc insulin suspensions in neutral pH range.

When zinc insulin suspensions of different pH values were prepared in the presence of sodium chloride, an unusually high sedimentation volume was found at about pH 6.9. An experimental investigation was conducted in an effort to understand this phenomenon. The experiments involved measurements of electrophoretic mobilities to calculate zeta potentials and sedimentation volumes of zinc insulin suspensions prepared at different NaCl concentrations (0, 17, and 120 mM) and at various pH values from 5 to 8. The general trend observed was that the magnitude of the zeta potential increased with pH when it was higher than the isoelectric point of 5.3. When the sodium chloride concentration was 120 mM, a very rapid change in zeta potential was observed in the pH range of 6.6 to 7.2, with a maximum magnitude of zeta potential at about pH 6.9, the same pH that was observed to yield the largest sedimentation volume. Our experimental results indicate that the greatest adsorption of chloride ion on the zinc insulin suspension particles occurred in the same pH range, which appeared to be responsible for the rapid change of zeta potential in that pH range. The experimental data were interpreted by DLVO (Derjaguin, Landau, Vervey, and Overbeek) theory, which involves a comparison of the forces of electrostatic repulsion and of the van der Waals attraction.

Chemical Phenomena↗
PubMed1990

Dental implant abutment resembling the two-phase tooth mobility.

Natural teeth and dental implants have differing degrees of mobility thus causing a potential biomechanical problem when connected by fixed bridgework. The clinical follow-up often discloses marginal bone loss around an implant neck probably due to high stress factors. An implant with a built-in compliance resembling the tooth mobility could be advantageous for stress distribution. With axial loading the proposed 'elastic'-test model accomplishes this demand. By means of theoretical and experimental studies this 'elastic'-test model is optimized and compared with a stiff implant-model. The results show a 20 times reduction of stress accumulation in bone with the 'elastic'-test model.

Biocompatible Materials↗
PubMed1983

[Effect of the electrochemical sodium gradient on alanine transport in 3T6 and CHO cells].

The dependence of L-alanine uptake by 3T6 and CHO-K1 cells on Na+ electrochemical gradient has been studied. The Na+ chemical gradient was changed by a short-term (partial or complete) replacement of Na+ for choline. The membrane potential change was achieved by addition of potassium ionophore--valinomycin (10 microM) into the medium. It is determined that the value of Km for alanine uptake by 3T6 cells increases from 2 mM, with 140 mM Na+ in the medium, up to 30 mM, if the replacement of Na+ for choline is complete. Similar results are obtained for CHO cells. The membrane potential increase under the influence of valinomycin leads to the increase in the value of Vmax of the uptake. The data obtained are interpreted on the basis of the well known scheme of Na+ alanine complex transfer, where Na+ increases the affinity of the carrier to the amino acid, and the membrane potential increases the carrier mobility.

Alanine↗
PubMed1989

Membrane fluidity and cancer metastasis.

The membrane fluidity of murine B16 melanoma and L5178 lymphoma variants is examined in relation to their metastatic potential. A higher lateral mobility of membrane proteins in metastasis is indicated by lectin receptor-mediated agglutination studies, but these do not constitute incontrovertible evidence that higher fluidity might be relevant in the metastatic process. The membranes of tumour cells with higher metastatic potential have a lower cholesterol/phospholipid ratio but greater unsaturated phospholipid content. This is partly supported by partition characteristics of metastatic variants in aqueous two-polymer phases. Steady-state fluorescence polarisation, which measures lipid order and the degree of rotational motion of lipids, does not suggest marked differences in bulk 'fluidity' of metastatic variants. Transbilayer fluidity differences have been described and these may be of some significance in the control of activity of membrane-associated enzymes and other membrane properties. The plasma membrane is a mosaic of domains possessing different degrees of microviscosity and this mosaicism may be relevant in the context of metastatic dissemination of tumours.

Animals↗
PubMed1998

Disrupted mobile aortic plaques are a major risk factor for systemic embolism in the elderly.

Protruding aortic plaques--especially those with mobile properties--on transesophageal echocardiography (TEE) are a potential source of stroke and systemic embolism in the elderly. Whether the various morphologies of atheromas with mobile components represent potential differences in the risk for embolic events has not been thoroughly elucidated. The goal of the present study was to determine the association between embolic events and the various types of mobile lesions in the thoracic aorta. Our population consisted of 569 consecutive patients (age 18-83 years) referred for TEE over 27 months; 108 (19%) of them were referred to evaluate recent embolism (cerebral in 97 and peripheral or both in 11; group I) and the remaining 461 were admitted for reasons unrelated to embolism (group II). In group I, 35 patients (32%) exhibited protruding plaques; those were fixed in 10 (9%) and with a mobile component in 25 (23%). In group II, plaques were found in only 13 patients (3%); fixed in 9 (2%) and mobile in 4 (1 %). Twenty-four patients with mobile lesions in group I were > 50 years old, and 21 of them (88%) were > 60 years old. While the presence of fixed plaques was associated with a moderate increase in the risk for systemic embolism (adjusted odds ratio 4.1; 95% confidence interval 1.3-56.4), mobile lesions were linked to a striking augmentation of this risk (odds ratio 30.1; 95% confidence interval 7.8-132.6). The majority of mobile lesions (76%) in group I represented disrupted atheromas with characteristic ulcerations or echolucency within the plaque suggestive of intraatheroma hemorrhage, whereas these TEE features were not observed in 89% of the mobile lesions in group II (p = 0.0003). We conclude that among the various types of mobile aortic lesions, the disrupted protruding plaques are a major risk factor for stroke and embolic events in the elderly.

Adolescent↗