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PubMed1991

Availability of fluoride from glass-ionomer luting cements in human saliva.

Fluoride availability from two glass-ionomer luting agents, Ketac-Cement and Aqua-Cement, was monitored after a 1-h treatment in distilled water at pH 7. The recorded results were then compared to the ones obtained from those same cements, after 1 h, in saliva, in water pretreated with saliva (pH 7 and 4.5), and in albumen and phosphate buffer solutions (pH 7). The Mann-Whitney two-sample rank test was utilized in order to identify the differences. The presence of proteins and phosphate reduced fluoride availability. A reduction in the pH from 7 to 4.5 resulted in an increased rate of fluoride release, in water, from glass-ionomers pretreated with saliva. The present study indicates that fluoride availability from glass-ionomers, in vivo, is pH controlled. The rate controlling factors appear to be phosphate and proteins.

Acrylic Resins↗

PubMed1995

Parents' attitudes and beliefs about HIV/AIDS prevention with condom availability in New York City public high schools.

In 1991, the New York City Board of Education expanded HIV/AIDS education to include condom availability in every public high school. The evaluation was designed to examine the impact of the program on students and monitor changes in parent's knowledge, attitudes, and beliefs. Findings are reported from the first wave of data from the parent survey, 716 parents from 12 randomly chosen NYC high schools and 81 parents from 12 focus groups held at six of the schools. Sixty-nine percent of parents believed students should be able to receive condoms at school, although nearly half felt they should have the right to keep their children from doing so. Most believed making condoms available would result in safer sex practices among students who were sexually active. Data suggest parents support the school's role in reducing HIV/AIDS transmission among adolescents and believe making condoms available represents an acceptable component of an HIV/AIDS prevention program.

Adolescent↗

PubMed1999

School violence, substance use, and availability of illegal drugs on school property among US high school students.

To determine if school violence is associated with substance use and availability of illegal drugs at school, this study examined data from the 1995 Youth Risk Behavior Survey, a nationally representative sample of 10,904 high school students. Adjusted odds ratios were calculated to describe the associations of tobacco, alcohol, and marijuana use (on and off school property), and availability of illegal drugs at school with five indicators of school violence--weapon-carrying, physical fighting, having property stolen or damaged, being threatened or injured, and being absent from school because of feeling unsafe. School violence indicators increased with the number of substances used and the location of use (on school property vs. off school property). School violence was associated with availability of illegal drugs at school, even among students who did not use substances. These findings suggest a need for coordinated violence and substance use prevention programs for youth in school and community settings.

Adolescent↗

PubMed2005

Competitive foods and beverages available for purchase in secondary schools--selected sites, United States, 2004.

School Health Profiles is conducted biennially to assess characteristics of school health programs. State and local departments of education and health select either all public secondary schools within their jurisdictions or a systematic, equal-probability sample of public secondary schools to participate in School Health Profiles. At each school, the principal and lead health education teacher were sent questionnaires to be self-administered and returned to the state or local agency conducting the survey. In 2004, a total of 27 states and 11 large urban school districts obtained weighted data from their survey of principals. The findings in this report indicate that the majority of secondary schools in 27 states and 11 large urban school districts allow students to purchase snack foods or beverages from vending machines or at the school store, canteen, or snack bar. The types of competitive foods and beverages available for purchase varied across states and large urban school districts. Overall, fruits or vegetables were less likely to be available for purchase than the other types of foods or beverages. Bottled water and soft drinks, sports drinks, or fruit drinks that are not 100% juice were most likely to be available for purchase.

Carbonated Beverages↗

PubMed2004

Acetyl group availability influences phosphocreatine degradation even during intense muscle contraction.

We previously established that activation of the pyruvate dehydrogenase complex (PDC) using dichloroacetate (DCA) reduced the reliance on substrate-level phosphorylation (SLP) at the onset of exercise, with normal and reduced blood flow. PDC activation also reduced fatigue development during contraction with reduced blood flow. Since these observations, several studies have re-evaluated our observations. One study demonstrated a performance benefit without a reduction in SLP, raising a question mark over PDC's role in the regulation of ATP regeneration and our interpretation of fatigue mechanisms. Using a model of muscle contraction similar to the conflicting study (i.e. tetanic rather than twitch stimulation), we re-examined this question. Using canine skeletal muscle, one group was infused with saline while the other was pretreated with 300 mg (kg body mass)(-1) DCA. Muscle biopsies were taken at rest, peak tension (1 min) and after 6 min of tetanic electrical stimulation (75 ms on-925 ms off per second) and blood flow was limited to 25% of normal values observed during contraction. DCA reduced phosphocreatine (PCr) degradation by 40% during the first minute of contraction, but did not prevent the almost complete depletion of PCr stores at 6 min, while muscle fatigue did not differ between the two groups. During intermittent tetanic stimulation PCr degradation was 75% greater than with our previous 3 Hz twitch contraction protocol, despite a similar rate of oxygen consumption at 6 min. Thus, in the present study enhanced acetyl group availability altered the time course of PCr utilization but did not prevent the decline towards depletion. Consistent with our earlier conclusions, DCA pretreatment reduces muscle fatigue only when SLP is attenuated. The present study and our met-analysis indicates that enhanced acetyl group availability results in a readily measurable reduction in SLP when the initial rate of PCr utilization is approximately 1 mmol (kg dry mass)(-1) s(-1) or less (depending on intrinsic mitochondrial capacity). When measured early during an uninterrupted period of muscle contraction, acetyl group availability is likely to influence SLP under any condition where mitochondria are responsible for a significant proportion of ATP regeneration.

Adenosine Triphosphate↗

PubMed2006

Human skeletal muscle intracellular oxygenation: the impact of ambient oxygen availability.

Intracellular oxygen (O2) availability and the impact of ambient hypoxia have far reaching ramifications in terms of cell signalling and homeostasis; however, in vivo cellular oxygenation has been an elusive variable to assess. Within skeletal muscle the extent to which myoglobin desaturates (deoxy-Mb) and the extent of this desaturation in relation to O2 availability provide an endogenous probe for intracellular O2 partial pressure (P(iO2)). By combining proton nuclear magnetic resonance spectroscopy (1H NMRS) at a high field strength (4 T), assessing a large muscle volume in a highly efficient coil, and extended signal averaging (30 min) we assessed the level of skeletal muscle deoxy-Mb in 10 healthy men (30 +/- 4 years) at rest in both normoxia and hypoxia (10% O2). In normoxia there was an average deoxy-Mb signal of 9 +/- 1%, which, when converted to P(iO2) using an O2/Mb half-saturation (P50) of 3.2 mmHg, revealed an P(iO2) of 34 +/- 6 mmHg. In ambient hypoxia the deoxy-Mb signal rose to 13 +/- 3% (P(iO2) = 23 +/- 6 mmHg). However, intersubject variation in the defence of arterial oxygenation (S(aO2)) in hypoxia (S(aO2) range: 86-67%) revealed a significant relationship between the changes in S(aO2) and P(iO2)(r2 = 0.5). These data are the first to document resting intracellular oxygenation in human skeletal muscle, highlighting the relatively high P(iO2) values that contrast markedly with those previously recorded during exercise (approximately 2-5 mmHg). Additionally, the impact of ambient hypoxia on P(iO2) and the relationship between changes in S(aO2) and P(iO2) stress the importance of the O2 cascade from air to cell that ultimately effects O2 availability and O2 sensing at the cellular level.

Adult↗

PubMed2001

Available space and extracellular transport of macromolecules: effects of pore size and connectedness.

Molecular exclusion in tumor tissues is one of the limiting factors for drug delivery to tumor cells. It can be quantified by the available volume fraction of solutes (K(AV)). We found in a previous study that K(AV) of dextran in tumor tissues decreased sharply when the molecular weight (MW) of dextran was increased from 40,000 to 70,000. Outside this range, K(AV) was less sensitive to the MW of dextran. To understand the mechanisms of the MW dependence of K(AV), we investigated K(AV) in tissue phantoms composed of tumor cells in 1% agarose gels, and performed numerical simulations of the available volume fraction in pore networks. We found that the MW dependence of K(AV) in tissue phantoms was similar to that in tumor tissues when the volume fraction of cells in the former was approximately 30%. Our numerical simulations revealed that the sharp decrease in K(AV) required two necessary conditions: (i) the existence of at least two populations of pores and (ii) the lack of connectedness of available pores in the interstitial space. Furthermore, results in this study suggest that it is important to consider not only the local structures of pores but also their connectedness in analyses of molecular transport in tissues.

Biological Transport, Active↗

PubMed1986

Availability of ferric iron for microbial reduction in bottom sediments of the freshwater tidal potomac river.

The distribution of Fe(III), its availability for microbial reduction, and factors controlling Fe(III) availability were investigated in sediments from a freshwater site in the Potomac River Estuary. Fe(III) reduction in sediments incubated under anaerobic conditions and depth profiles of oxalate-extractable Fe(III) indicated that Fe(III) reduction was limited to depths of 4 cm or less, with the most intense Fe(III) reduction in the top 1 cm. In incubations of the upper 4 cm of the sediments, Fe(III) reduction was as important as methane production as a pathway for anaerobic electron flow because of the high rates of Fe(III) reduction in the 0- to 0.5-cm interval. Most of the oxalate-extractable Fe(III) in the sediments was not reduced and persisted to a depth of at least 20 cm. The incomplete reduction was not the result of a lack of suitable electron donors. The oxalate-extractable Fe(III) that was preserved in the sediments was considered to be in a form other than amorphous Fe(III) oxyhydroxide, since synthetic amorphous Fe(III) oxyhydroxide, amorphous Fe(III) oxyhydroxide adsorbed onto clay, and amorphous Fe(III) oxyhydroxide saturated with adsorbed phosphate or fulvic acids were all readily reduced. Fe(3)O(4) and the mixed Fe(III)-Fe(II) compound(s) that were produced during the reduction of amorphous Fe(III) oxyhydroxide in an enrichment culture were oxalate extractable but were not reduced, suggesting that mixed Fe(III)-Fe(II) compounds might account for the persistence of oxalate-extractable Fe(III) in the sediments. The availability of microbially reducible Fe(III) in surficial sediments demonstrates that microbial Fe(III) reduction can be important to organic matter decomposition and iron geochemistry. However, the overall extent of microbial Fe(III) reduction is governed by the inability of microorganisms to reduce most of the Fe(III) in the sediment.

Journal Article↗

PubMed2002

Construction and characterization of a proU-gfp transcriptional fusion that measures water availability in a microbial habitat.

We constructed and characterized a transcriptional fusion that measures the availability of water to a bacterial cell. This fusion between the proU promoter from Escherichia coli and the reporter gene gfp was introduced into strains of E. coli, Pantoea agglomerans, and Pseudomonas syringae. The proU-gfp fusion in these bacterial biosensor strains responded in a quantitative manner to water deprivation caused by the presence of NaCl, Na(2)SO(4), KCl, or polyethylene glycol (molecular weight, 8000). The fusion was induced to a detectable level by NaCl concentrations of as low as 10 mM in all three bacterial species. Water deprivation induced proU-gfp expression in both planktonic and surface-associated cells; however, it induced a higher level of expression in the surface-associated cells. Following the introduction of P. agglomerans biosensor cells onto bean leaves, the cells detected a significant decrease in water availability within only 5 min. After 30 min, the populations were exposed, on average, to a water potential equivalent to that imposed by approximately 55 mM NaCl. These results demonstrate the effectiveness of a proU-gfp-based biosensor for evaluating water availability on leaves. Furthermore, the inducibility of proU-gfp in multiple bacterial species illustrates the potential for tailoring proU-gfp-based biosensors to specific habitats.

Amino Acid Transport Systems↗

PubMed2003

Evaluation of four commercially available Epstein-Barr virus enzyme immunoassays with an immunofluorescence assay as the reference method.

Four commercially available enzyme immunoassays (EIAs) (Novitec, Biotest, Virotech, and DiaSorin) were evaluated, with an indirect immunofluorescence assay as the reference method, for Epstein-Barr virus (EBV) VCA (viral capsid antigen) immunoglobulin G (IgG), VCA IgM, or EBNA (EBV nuclear antigen) IgG at three different locations (Homburg, Stuttgart, and Dresden). Serum samples from 66 immunocompetent patients with infectious mononucleosis, 73 patients without prior EBV infection, and 96 patients with past EBV infections and 29 serum samples with possible cross-reactions to other herpesviruses were included. In addition, 25 samples from an extensively pretested panel that is commercially available (Boston Biomedica) were tested. Each sample was tested at only one location. The four EIAs varied considerably in performance. When analyzing for EBV diagnosis, the Novitec assay performed the best, with 4.9% discrepant diagnoses, followed by the Biotest, Virotech, and DiaSorin assays, with 6.8, 11.7, and 14.0% discrepant diagnoses, respectively. On the basis of single-parameter analysis, the Novitec assay also showed the lowest number of discrepant results, with 3.5%, compared with the Virotech, Biotest, and DiaSorin assays, which produced 5.4, 6.4, and 8.6% discrepant results, respectively. VCA assays using affinity-purified native antigens performed better than assays with recombinant or synthetic antigens. The synthetic EBNA-1s showed the lowest concordance with the reference compared to recombinant p72. Commercially available EBV EIAs differed considerably in performance; however, some proved to be reliable and convenient alternatives to the indirect immunofluorescence assay for routine diagnostics. Native antigens, rather than synthetic peptides, are favored for EBV serology testing.

Antigens, Viral↗

PubMed1991

Relative availability of transferrin-bound iron and cell-derived iron to aerobactin-producing and enterochelin-producing strains of Escherichia coli and to other microorganisms.

A method is described for determination of the relative availability of transferrin-bound iron and cell-derived iron to microbial iron-scavenging mechanisms. This involved incubation of parallel cultures of microorganisms in dialysis tubes placed in RPMI 1640 tissue culture medium containing 30%-iron-saturated transferrin and K562 erythroleukemia cells. In one culture the transferrin was labelled with 59Fe and in the other the cells were labelled, and the relative uptake of radioiron by the microorganisms determined. The results showed that Staphylococcus epidermidis and Staphylococcus aureus acquired iron predominantly from cells, while Candida albicans and the enteropathogenic Escherichia coli NCTC 8623 tended to acquire iron from transferrin. E. coli K-12 strains W3110 and LG1705, which (like NCTC 8623) produce the siderophore enterochelin but not aerobactin, acquired predominantly transferrin-bound iron, whereas the related E. coli strains LG1315 and LG1628, which produce aerobactin but not enterochelin, showed a preference for cell-derived iron. When the cells were incubated in the presence of 59Fe-labelled transferrin and 55Fe-labelled ferritin, no difference in relative availability of iron to E. coli was observed, suggesting that differences in the ability of aerobactin and enterochelin to remove iron from intracellular ferritin were not responsible for this preference. These results may help to explain why production of aerobactin, despite its relatively low affinity for iron, is more closely associated with invasiveness in E. coli than is enterochelin production. Reduced availability of cell-bound iron during inflammation may contribute to antimicrobial defenses.

Candida albicans↗

PubMed2003

Accuracy of six commercially available systems for identification of members of the family vibrionaceae.

Six commercially available bacterial identification products were tested with Vibrio alginolyticus (12 strains), V. cholerae (30 strains), Photobacterium (Vibrio) damselae (10 strains), V. fluvialis (10 strains), V. furnissii (4 strains), V. hollisae (10 strains), V. metschnikovii (9 strains), V. mimicus (10 strains), V. parahaemolyticus (30 strains), and V. vulnificus (10 strains) to determine the accuracy of each system for identification. The products included API 20E, Crystal E/NF, MicroScan Neg ID2 and Rapid Neg ID3, and Vitek GNI+ and ID-GNB. Each product was tested only with those species that were listed in its database. Overall, the systems correctly identified 63.9, 80.9, 63.1, 73.6, 73.5, and 77.7% of the isolates to species level, respectively. Error rates ranged from 0.8% for the API 20E to 10.4% for the Rapid Neg ID3. The API 20E gave "no identification" for 13.1% of the isolates, while the Neg ID2, GNI+, ID-GNB, and Crystal were unable to identify 1.8, 2.9, 5.0, and 6.9%, respectively. For V. cholerae, specifically, accuracy ranged from 50.0 to 96.7%, with the API 20E having the worst performance and Crystal having the best. V. fluvialis presented the biggest challenge for the API 20E and the GNI+, with probabilities averaging 10%, while V. mimicus was a major problem with the Crystal E/NF, which identified none of the strains correctly. With the Neg ID2, correct answers were often obtained only after a modified inoculation of the panel with a bacterial suspension prepared with 0.85% NaCl. Additional tests required for identification often included growth in the absence of NaCl, which is not readily available in most clinical laboratories. The only product to correctly identify at least 90% of V. cholerae strains was the Crystal E/NF, and only three of the six products, the API 20E and both of the Vitek cards, correctly identified more than 90% of the V. parahaemolyticus strains. Thus, extreme care must be taken in the interpretation of answers from these six commercially available systems for the identification of Vibrio species.

Gram-Negative Bacterial Infections↗

PubMed2005

A controlled study on batted ball speed and available pitcher reaction time in slowpitch softball.

OBJECTIVES: To investigate safety risks in slowpitch softball by conducting laboratory and experimental studies on the performance of high tech softball bats with polyurethane softballs. To compare the results with the recommended safety standards. METHODS: ASTM standard compression testing of seven softball models was conducted. Using these seven softball models, bat/ball impact testing was performed using seven adult male softball players and six high tech softball bat models to determine mean batted ball speeds. Over 500 bat/ball impact measurements were recorded and analysed. Available pitcher reaction time was calculated from the mean batted ball speed measurements. RESULTS: According to the United States Specialty Sports Association and the Amateur Softball Association, the maximum initial batted ball speed should be 137.2 km/h, which corresponds to a minimum pitcher reaction time of 0.420 second. These experiments produced mean batted ball speeds of 134.0-159.7 km/h, which correspond to available pitcher reaction times of 0.409-0.361 second. CONCLUSION: The use of high tech softball bats with polyurethane softballs can result in batted ball speeds that exceed the recommended safety limits, which correspond to decreased available pitcher reaction times.

Athletic Injuries↗

PubMed1979

Effects of stopping smoking for 48 hours on oxygen availability from the blood: a study on pregnant women.

The effects of stopping smoking for 48 hours on factors governing the availability of oxygen from the blood--that is, carboxyhaemoglobin (COHb), haemoglobin-oxygen (HbO2) affinity, and haemoglobin concentration--were measured in women in the last trimester of pregnancy. Three groups were studied: smokers, smokers who stopped smoking for 48 hours, and non-smokers. The 22 smokers had higher initial COHb values and greater HbO2 affinity than the 10 non-smokers, but their total haemoglobin concentrations were also higher, so that their oxygen availability was not significantly reduced. In the 11 smokers who stopped the reduction in COHb and decrease in HbO2 affinity led to a significant increase of 8% in "available oxygen" in 48 hours. Since even small improvements in oxygen delivery to the tissues may confer critical benefit to the fetus, particularly during labour or when exposed to general anaesthesia, smoking should be discouraged for 48 hours before elective deliveries. The same consideration might reasonably be applied to patients undergoing general anaesthesia for all elective operations.

Carboxyhemoglobin↗

PubMed1982

Availability of computed tomography for the management of head injuries in England and Wales.

Senior neuroradiologists or radiologists of 42 hospitals with computed tomography available for NHS patients in England and Wales were contacted by postal questionnaire about the use of this facility in the management of patients with acute head injuries. Replies were obtained from 39 hospitals. Requests for computed tomography from general surgeons or physicians and staff of accident and emergency departments received positive responses for scanning with only half to three-quarters the frequency of responses to requests from neurosurgeons. Continuous computed tomography facilities were available generally to neurosurgeons. The combined effect of partial responses to requests and the availability of the computed tomography service meant that only 44% of hospitals gave a continuous service for general surgeons or physicians. The percentage of hospitals giving a continuous service to accident and emergency departments was 54%. It appeared that computed tomography scanning was being used most often as a diagnostic/management instrument after clinical selection among patients with head injuries rather than as an instrument to be used in primary assessment.

Craniocerebral Trauma↗

PubMed1997

Relation between bed use, social deprivation, and overall bed availability in acute adult psychiatric units, and alternative residential options: a cross sectional survey, one day census data, and staff interviews.

OBJECTIVES: To examine the relation between bed use, social deprivation, and overall bed availability in acute adult psychiatric units and to explore the range of alternative residential options. DESIGN: Cross sectional survey, combined with one day census data; ratings by and interviews with staff; examination of routine data sources. SETTINGS: Nationally representative sample of acute psychiatric units. SUBJECTS: 2236 patients who were inpatients on census day. MAIN OUTCOME MEASURES: Bed occupancy levels, judged need for continuing inpatient care, reasons preventing discharge, scores on the Health of the Nation outcome scales. RESULTS: Bed occupancy was related to social deprivation and total availability of acute beds (r = 0.66, 95% confidence interval 0.19 to 0.88, F = 8.72, df = 2.23; P = 0.002). However, 27% (603/2215) of current inpatients (61% (90/148) of those with stays of > 6 months) were judged not to need continuing admission. The major reasons preventing discharge were lack of suitable accommodation (37% (176/482) of patients in hospital < 6 months v 36% (31/86) of those in hospital > 6 months); inadequate domiciliary based community support (23% (113) v 9% (8)); and lack of long term rehabilitation places (21% (100) v 47% (40)). Scores on the Health of the Nation outcome scale were generally consistent with these staff judgments. CONCLUSIONS: The shortage of beds in acute psychiatric units is related to both social deprivation and the overall availability of acute beds. Patients currently inappropriately placed on acute admission wards should be relocated into more suitable accommodation, either in hospital or in the community. A range of provisions is required; simply providing more acute beds is not the answer.

Acute Disease↗

PubMed2005

Impact on contraceptive practice of making emergency hormonal contraception available over the counter in Great Britain: repeated cross sectional surveys.

OBJECTIVE: To examine the impact on contraceptive practice of making emergency hormonal contraception available over the counter. DESIGN: Analysis of data on contraceptive practice for women aged 16-49 years in the period 2000-2 from the Omnibus Survey, a multipurpose survey in which around 7600 adults living in private households are interviewed each year. SETTING: Private households in Great Britain. MAIN OUTCOME MEASURES: Use of different types of contraception and rates of unprotected sex. RESULTS: After emergency hormonal contraception was made available over the counter, levels of use of different types of contraception by women aged 16-49 remained similar. No significant change occurred in the proportion of women using emergency hormonal contraception (8.4% in 2000, 7.9% in 2001, 7.2% in 2002) or having unprotected sex. A change did, however, occur in where women obtained emergency hormonal contraception; a smaller proportion of women obtained emergency hormonal contraception from physicians and a greater proportion bought it over the counter. No significant change occurred in the proportion of women using more reliable methods of contraception, such as the oral contraceptive pill, or in the proportion of women using emergency hormonal contraception more than once during a year. CONCLUSIONS: Making emergency hormonal contraception available over the counter does not seem to have led to an increase in its use, to an increase in unprotected sex, or to a decrease in the use of more reliable methods of contraception.

Adolescent↗

PubMed2005

Effects on alcohol related fatal crashes of a community based initiative to increase substance abuse treatment and reduce alcohol availability.

OBJECTIVE: This analysis tested whether comprehensive community interventions that focus on reducing alcohol availability and increasing substance abuse treatment can reduce alcohol related fatal traffic crashes. INTERVENTION: Five of 14 communities awarded Fighting Back grants by The Robert Wood Johnson Foundation to reduce substance abuse and related problems attempted to reduce availability of alcohol and expand substance abuse treatment programs (FBAT communities). Program implementation began on 1 January 1992. DESIGN: A quasi-experimental design matched each program community to two or three other communities of similar demographic composition in the same state. MAIN OUTCOME MEASURES: The ratio of fatal crashes involving a driver or pedestrian with a blood alcohol concentration of 0.01% or higher, 0.08% or higher, or 0.15% or higher were examined relative to fatal crashes where no alcohol was involved for 10 years preceding and 10 years following program initiation. RESULTS: Relative to their comparison communities, the five FBAT communities experienced significant declines of 22% in alcohol related fatal crashes at 0.01% BAC or higher, 20% at 0.08% or higher, and 17% at 0.15% or higher relative to fatal crashes not involving alcohol. CONCLUSIONS: Community interventions to reduce alcohol availability and increase substance abuse treatment can reduce alcohol related fatal traffic crashes.

Accidents, Traffic↗