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PubMed1996

Effects of sugar availability on the blood-feeding behavior of Anopheles gambiae (Diptera:Culicidae).

Blood-feeding behavior and survivorship of individual Anopheles gambiae Giles females were observed daily in cohorts with either access to sugar (n = 76) or without sugar (n = 80). Individual mosquitoes were allowed to feed daily on an anesthetized mouse. Mosquitoes provided with sugar lived on average almost 3 d longer than females without sugar (19.0 versus 16.2 d). After stratification by age, mosquitoes in the youngest (5-12 d) and middle (13-19 d) age strata showed no differences in blood-feeding patterns relative to sugar availability. However, mosquitoes from the oldest age group and no access to sugar had more total blood feeds than long-lived females ( > or = 20 d) with access to sugar (9.8 versus 6.5). Furthermore, mosquitoes > or = 20 d old and without sugar available had a higher blood-feeding frequency than females that had sugar available (0.36 versus 0.25 blood meals per female per day). The enhanced blood-feeding capability among older sugar-deprived An. gambiae emphasized the close association between sugar-feeding and blood-feeding behavior and the potential consequences for the transmission of malaria parasites and other pathogens.

Animals↗

PubMed1975

Computer-based method for calculation of the available energy of proteins.

An aspect of protein nutrition that has not been resolved in a satisfactory manner is the utilizable energy equivalence of proteins. The existing methods overestimate the utilizable energy of proteins. A more accurate method fo calculating the utilizable energy of proteins is to calculate the moles of adenosine triphosphate formed during the complete oxidation of a given amount of proteins. The moles of adenosine triphosphate formed can be calculated from knowledge of the amino acid composition and knowledge of the metabolic pathway for each amino acid. A computer program is described that provides the bookkeeping required for these calculations. The available energy of a protein is calculated in this computer-based method by adjusting the energy value of the proteins so that it is equivalent to that of carbohydrates and fats in providing the energy for adenosine triphosphate formation. The computer-based method was used to calculate the available energy of a group of proteins of known amino acid composition. The available energy varied from 3.02 keal/g for colagen to 3

Adenosine Triphosphate↗

PubMed1977

Biohydrogenation and availability of linoleic acid in lactating cows.

Linoleic acid biohydrogenation, absorption and availability for maintenance and milk production in dairy cows fed high grain (60--85% of dry matter) diets were quantitatively estimated by isotope dilution, using two methods of dosing. [1-14C]Linoleic acid-labeled chylomicra and very low density lipoproteins (VLDL) were obtained from lymph of a calf fed [1-14C]linoleic acid and fitted with a thoracic duct-venous shunt. Labeled chylomicra were injected intravenously into two cows: a Jersey (trial 1), and a Holstein (trial 2). Labeled VLDL was injected intravenously into a Holstein cow (trial 3). In trials 4 and 5 the [1-14C]linoleic acid was placed into the omasal canal of two rumen-fistulated Holstein cows. Linoleic acid biohydrogenation (%), absorption (g/day), and availability above requirements for milk production (mg/kg body wt 3/4) were: 68.1 +/- 2.28, 52.1 +/- 2.92, and 244 +/- 19.4 (mean +/- SE), respectively. The biohydrogenation data indicate that both methods of dosing the cows were equally dependable. The estimates of linoleic acid biohydrogenation are consistent with limited data previously reported, indicating that the isotope dilution technique used is a reliable method to estimate linoleic acid absorption in lactating cows. Linoleic acid available to the lactating cow above milk production requirements was more than double the requirement of weanling female rats, when compared on the basis of metabolis body size.

Animal Feed↗

PubMed1978

Estimation of the fraction of the lactose in a high lactose diet available for fermentation in the cecum and colon of the rat.

Experiments were conducted to determine the amount of lactose which passed into the large intestine and the lactase activity in the small intestine of rats (200 g) fed a control diet or a diet containing 30% lactose. The fraction of lactose consumed in a single 1-hour meal that escaped hydrolysis in the small intestine was estimated by measuring the area under a smooth curve of a plot of lactose:marker ratio in the terminal ileum expressed as a fraction of intake, against the fraction of the total marker that passed into the large intestine. This amounted to approximately 30% and 31.5% of the lactose consumed for the rats fed the control and 30% lactose diets, respectively. In another experiment in which the rats were fed a diet containing 30% lactose and the Cr-EDTA marker ad libitum for 1 week, approximately 43% of the lactose consumed became available for fermentation in the large intestine. This work suggests that a substantial fraction of the lactose ingested is available for fermentation in the large intestine. The lactase activity of homogenates of the small intestine of rats fed the control or high lactose diet was 106 +/- 5 or 115 +/- 4 mg lactose/30 minutes/rat (P less than 0.05), respectively. The lactase activity in the small intestine homogenate (mucosa + contents) was significantly higher than that actually available in vivo (110 +/- 7 versus 69 +/- 4 mg/30 minutes/rat).

Animals↗

PubMed1989

Prolonged acetaminophen ingestion in mice: effects on the availability of methionine for metabolic functions.

The objective of this study was to determine the effect of prolonged ingestion of acetaminophen (ACAP) on the availability of methionine for its metabolic functions in mice. ACAP was fed to weanling mice at levels of 0.0, 0.3, 0.5 or 0.8% of the diet, with methionine provided at requirement (0.5%) or at twice the requirement (1.0%) level, for 2 wk to assess its effect on the availability of methionine for growth. In another study, ACAP was fed to adult mice at levels of 0.0, 0.4, or 0.6% of the diet, with methionine at 0.5 or 1.0% of the diet, for 2 wk to assess its effect on the availability of methionine for protein synthesis and methylation reactions. The growth rate of weanling mice decreased with increasing dietary ACAP in mice fed 0.5% methionine, but not in those fed 1.0%. Hepatic reduced glutathione (GSH) decreased and plasma glutamic-pyruvic transaminase activity increased in an ACAP dose-dependent manner in weanling mice fed 0.5% methionine. Protein synthesizing ability decreased in adult mice fed 0.5% methionine and 0.6% ACAP. Relative liver weight and liver lipid decreased with increasing dietary ACAP in mice fed methionine at or above requirement. Neither plasma creatinine or muscle creatine was affected by variations in dietary methionine or ACAP. Ingestion of ACAP for a prolonged period of time increased the methionine requirement for growth, maintenance of hepatic GSH level and protein synthesis, but did not affect the methionine requirement for methylation reactions.

Acetaminophen↗

PubMed2005

From treatment to prevention: the interplay between HIV/AIDS treatment availability and HIV/AIDS prevention programming in Khayelitsha, South Africa.

There is a paucity of research that illustrates the interplay between HIV/AIDS treatment and prevention programs. We describe the central role that public access to antiretroviral (ARV) medication has played in the development and efficacy of HIV/AIDS prevention programming in Khayelitsha, a resource-poor township in the Western Cape of South Africa. We document the range of preventive interventions and services available in Khayelitsha since the early 1990s and explore the impact of ARV availability on prevention efforts and disease stigma on the basis of extensive indepth interviews, supplemented by data collection. The information gathered suggests that the introduction of the mother-to-child-transmission (MTCT) prevention programs in 1999 and the three HIV treatment clinics run by Doctors Without Borders/Médecins Sans Frontières (MSF) in 2000 were turning points in the region's response to the HIV/AIDS epidemic. These programs have provided incentives for HIV testing, galvanized HIV/AIDS educators to reach populations most at risk, and decreased the HIV incidence rates in Khayeltisha compared to other areas in the Western Cape. Lessons learned in Khayelitsha about the value of treatment availability in facilitating prevention efforts can inform the development of comprehensive approaches to HIV/AIDS in other resource-poor areas.

Anti-HIV Agents↗

PubMed2006

The International Gene Trap Consortium Website: a portal to all publicly available gene trap cell lines in mouse.

Gene trapping is a method of generating murine embryonic stem (ES) cell lines containing insertional mutations in known and novel genes. A number of international groups have used this approach to create sizeable public cell line repositories available to the scientific community for the generation of mutant mouse strains. The major gene trapping groups worldwide have recently joined together to centralize access to all publicly available gene trap lines by developing a user-oriented Website for the International Gene Trap Consortium (IGTC). This collaboration provides an impressive public informatics resource comprising approximately 45 000 well-characterized ES cell lines which currently represent approximately 40% of known mouse genes, all freely available for the creation of knockout mice on a non-collaborative basis. To standardize annotation and provide high confidence data for gene trap lines, a rigorous identification and annotation pipeline has been developed combining genomic localization and transcript alignment of gene trap sequence tags to identify trapped loci. This information is stored in a new bioinformatics database accessible through the IGTC Website interface. The IGTC Website (www.genetrap.org) allows users to browse and search the database for trapped genes, BLAST sequences against gene trap sequence tags, and view trapped genes within biological pathways. In addition, IGTC data have been integrated into major genome browsers and bioinformatics sites to provide users with outside portals for viewing this data. The development of the IGTC Website marks a major advance by providing the research community with the data and tools necessary to effectively use public gene trap resources for the large-scale characterization of mammalian gene function.

Animals↗

PubMed1995

The Swedish insemination act and the availability of donors.

Sweden was in 1985 the first country in the world to enact legislation concerned with the practice of donor insemination (DI). Included in this legislation was the requirement that information about the identity of the donors be kept and be made available to the resultant offspring upon 'maturity', should they seek this. This provision has attracted much interest, debate and criticism, and claims have been made that this has led to a decline in the numbers of men coming forward to donate semen in Sweden. This paper presents data covering the pre- and post-legislation period from one clinic, along with the only available data on all the Swedish clinics providing DI, which covers a more limited post-legislation period. This data shows that there has been an increase in number of donors being recruited, suggesting that the possibility of future contact by genetic offspring has not had the negative impact on the availability of donors predicted.

Confidentiality↗

PubMed1995

Psychological morbidity and the availability of assisted conception: a group comparison study.

BACKGROUND: Given its limited availability, it is worth while to explore the relationship between the non-availability of assisted conception and psychological morbidity among subfertile women, to see if those denied the procedure experience poorer health. METHODS: A non-randomized group comparison study was carried out in Bradford Health Authority, England. Sixty-six women who had reached the point at which assisted conception was deemed appropriate, but for whom such treatments were not available, were compared with 49 parous women, and 73 newly diagnosed subfertile women. The General Wellbeing Index (GWI) was used to measure their psychological wellbeing. RESULTS: Cases and subfertile controls have similar levels of wellbeing, whereas parous controls have significantly higher average levels than cases. This pattern is seen in the simple unadjusted comparison and also when adjustments are made for the distributions of age, life event score and social class. CONCLUSIONS: Subfertile women experience poorer psychological health than similar parous women. Subfertile women, for whom assisted conception is an appropriate but unavailable treatment option, appear to have similar psychological health to those who are being investigated and treated by other means.

Adaptation, Psychological↗

PubMed2002

Effects of density and perch availability on the immune status of broilers.

This study attempted to evaluate the effect of various housing densities and perch availability on the immune status of commercial broilers. Birds were raised from hatch to 42 d of age with 10, 15, and 20 birds/m2 in pens, with and without the availability of horizontal perches. The immune parameters that were assessed were lymphoid organ weights, antibody response to SRBC in the last 10 d of growth, heterophil:lymphocyte ratios at 32 and 42 d of age, and lymphocyte blastogenesis of peripheral blood lymphocytes collected at 32 and 42 d of age. As density increased, bursa weight and bursa/body weight ratios decreased significantly (P < 0.05). Addition of perches to the pens also significantly decreased the bursa weights and bursa/body weight index (P < 0.01). No other significant effects were observed for the flock performance, morphometric data, or immunological tests between treatments. We concluded that under the conditions of this study, which tried to simulate commercial conditions, the bursal weight was the best indicator of stress that was related to housing density. Addition of perches appeared to increase this level of stress because the birds used the perches infrequently, and therefore there might have been a further reduction in the availability of floor space to the birds.

Animal Husbandry↗

PubMed2003

Total and water-soluble phosphorus in broiler litter over three flocks with alum litter treatment and dietary inclusion of high available phosphorus corn and phytase supplementation.

Three pen trials were conducted to determine the main effect of alum addition to litter on form of poultry litter P using a 2 x 2 factorial structure of the subunit treatments: diets including high available phosphorus/low phytate corn (HAPC) and phytase (PHYT). Male broilers (1,760 per flock) were grown to 42 d having starter diets with 0.45% available P and grower diets with 0.35% available P. In the first trial, total litter P (tP) was greatest for the yellow dent corn (YDC) diet (12 g/kg) and least for the HAPC and PHYT combination (H&P) diet (6.9 g/kg) with the individual PHYT and HAPC diets falling in between at 9.1 g/kg and 9.4 g/kg tP. Also in the first trial, the litter water-soluble P (wP) was highest for PHYT (2.8 g/kg), least for the HAPC and H&P diets (1.5 g/kg) with the YDC diet falling between (2.2 g/kg). Alum was added to the litter after the first experiment. In the second and third experiments, alum inclusion significantly reduced the wP when compared with the treatments with no alum. In the third trial, the least wP was present in the alum-HAPC treatment. Phytase, YDC, and HAPC diets with no alum litter treatment generated the most wP. Since these diets appear to have little or no difference with respect to quantity of wP, this work suggests that form of litter P generated by alternative diets should be considered as criteria when attempting to reduce P in broiler litter applied to land.

6-Phytase↗

PubMed2001

Commercially available folic acid supplements and their compliance with the British Pharmacopoeia test for dissolution.

A recent report suggested that some folic acid preparations available in the United States failed to meet the specifications for dissolution specified by the US Pharmacopoeia (USP), of 70 per cent drug release in the first hour of testing. The Teratology Society recommends that women of childbearing age should take a daily supplement of 400 microg folic acid when they are trying to conceive, to reduce the risk of foetal neural tube defects. The consequence of this failure to meet the USP requirements may be that an inadequate dose of folate may be absorbed and thus the expected level of protection against neural tube defects not afforded. The purpose of the present study was to examine a number of brands of folic acid (400 microg), available commercially in the United Kingdom, for compliance with the British Pharmacopoeia (BP) test for dissolution. Ten tablets (or capsules) from each of 11 brands were tested using dissolution apparatus compliant with BP requirements, using 0.1 M sodium hydroxide as the dissolution medium. The results indicated that four of the brands failed to release 70 per cent of the nominal drug content in the first hour of test and thus did not comply with the test. Two of the seven brands that passed the test went on to release more than 150 per cent of the nominal 400 microg drug content. These results highlight the problems of dose uniformity and the potential health risks of slow dissolution and under-dosing in commercially available folic acid dosage forms.

Absorption↗

PubMed2006

Range of self-tests available to buy in the United Kingdom: an Internet survey.

We aimed to describe the availability in the United Kingdom of self-tests that are used to diagnose or screen for conditions without involving a health professional. A systematic Internet search identified 104 unique self-tests related to 24 named conditions including cancers, chronic conditions and infections. These self-tests require various samples including blood obtained using a lancet. The samples are processed at home with results available in minutes or sent to a laboratory for processing with results returned to the individual by e-mail or post. Prices per self-test and condition range from < Pounds 1 to Pounds 76. Self-tests are readily available, and further work is needed to assess their impact.

Diagnostic Equipment↗

PubMed1997

Evaluation of commercially available tests for Chlamydia nucleic acid detection in synovial fluid of patients.

Since the presence of Chlamydia nucleic acids has been shown in synovial fluid (SF) from some patients with Chlamydia reactive arthritis, we investigated whether commercially available tests, developed to detect Chlamydia nucleic acids in urogenital samples, could also be used for their detection in SF samples. We therefore tested SF samples, found positive with at least two different systems of DNA amplification in a previous study, with three commercially available kits. No positive results were obtained. It is concluded that the commercially available tests Gen-Probe PACE 2, Amplicor (developed by Roche Molecular Systems) and LCx (developed by Abbott Laboratories) do not have sufficient sensitivity to detect reliably Chlamydia RNA or DNA in SF.

Antibodies, Bacterial↗

PubMed1993

Growth and photosynthesis of tropical forest tree seedlings (Bischofia javanica Blume) as influenced by a change in light availability.

Acclimation in seedlings of Bischofia javanica Blume, which are commonly found in canopy gaps in the moist forests of tropical Asia, to a change in light availability was examined in a controlled environment simulating forest shade and daylight. Seedlings were grown in a high (1000 micro mol m(-2) s(-1); red/far-red, 1.45) or low (40 micro mol m(-2) s(-1); red/far-red, 0.10) light regime and then transferred to the contrasting light environment for nine weeks. Control seedlings were maintained in the same light regime throughout the study. The availability of light influenced relative growth rate through morphological and physiological adjustments. Transferred seedlings retained the leaves that had been developed before transfer, and no leaf-shedding was observed till the end of the experiment. Leaves formed in the new light regime were physiologically and morphologically identical to those of the corresponding controls. High-light seedlings transferred to low light displayed significantly lower relative growth rate than the low-light controls because of a lower leaf area ratio carried over from the previous high-light environment. A reverse pattern of response with respect to relative growth rate was observed for the low-light seedlings transferred to high light compared to the high-light controls. The higher relative growth rate in the low-light seedlings transferred to high light was the result of higher net assimilation rate and higher leaf area ratio. The higher leaf area ratio in the low-light seedlings transferred to high light was the consequence of the effects of previous environment, and the relatively lower net assimilation rate in the high-light control seedlings was, at least partly, due to the effects of self-shading rather than to the photosynthetic capacity of the leaves. The results suggest that the species has a wide acclimation potential to a change in light availability that might occur in nature following gap creation or canopy closure.

Journal Article↗

PubMed1996

Fine root respiration in northern hardwood forests in relation to temperature and nitrogen availability.

We examined fine-root (< 2.0 mm diameter) respiration throughout one growing season in four northern hardwood stands dominated by sugar maple (Acer saccharum Marsh.), located along soil temperature and nitrogen (N) availability gradients. In each stand, we fertilized three 50 x 50 m plots with 30 kg NO(3) (-)-N ha(-1) year(-1) and an additional three plots received no N and served as controls. We predicted that root respiration rates would increase with increasing soil temperature and N availability. We reasoned that respiration would be greater for trees using NO(3) (-) as an N source than for trees using NH(4) (+) as an N source because of the greater carbon (C) costs associated with NO(3) (-) versus NH(4) (+) uptake and assimilation. Within stands, seasonal patterns of fine-root respiration rates followed temporal changes in soil temperature, ranging from a low of 2.1 micro mol O(2) kg(-1) s(-1) at 6 degrees C to a high of 7.0 micro mol O(2) kg(-1) s(-1) at 18 degrees C. Differences in respiration rates among stands at a given soil temperature were related to variability in total net N mineralized (48-90 micro g N g(-1)) throughout the growing season and associated changes in mean root tissue N concentration (1.18-1.36 mol N kg(-1)). The hypothesized increases in respiration in response to NO(3) (-) fertilization were not observed. The best-fit model describing patterns within and among stands had root respiration rates increasing exponentially with soil temperature and increasing linearly with increasing tissue N concentration: R = 1.347Ne(0.072T) (r(2) = 0.63, P < 0.01), where R is root respiration rate ( micro mol O(2) kg(-1) s(-1)), N is root tissue N concentration (mol N kg(-1)), and T is soil temperature ( degrees C). We conclude that, in northern hardwood forests dominated by sugar maple, root respiration is responsive to changes in both soil temperature and N availability, and that both factors should be considered in models of forest C dynamics.

Journal Article↗

PubMed1986

Uptake of carbon and nitrogen at decreased nutrient availability in small birch (Betula pendula Roth.) plants.

Uptake of carbon and nitrogen in relation to mineral nutrient supply was investigated in small birch (Betula pendula Roth.) plants grown in solution culture. A step-decrease in nutrient availability (from near-optimal to a low rate of supply) caused an immediate and temporary cessation in net uptake of nitrogen to leaves and a sharp reduction in rate of leaf expansion. Both net uptake of nitrogen to leaves and leaf area expansion subsequently resumed but at a rate matching the decreased nutrient supply. Whole plant- and root-relative growth rates also decreased with mineral nutrient supply, although root growth rate decreased more slowly than that of the whole plant, resulting in an increased fraction of plant dry matter in the roots. During the lag phase, net shoot photosynthesis exceeded carbon use in structural growth and respiration as indicated by high starch concentrations in the whole plant. Over a wide range of mineral nutrient availabilities, the stable ratios of leaf area and plant growth rate to plant nitrogen content remained unchanged. Starch concentrations were higher at the lower nutrient availabilities, suggesting that carbon uptake was not regulated solely by the rate of carbon use in structural growth and respiration. It was calculated that net photosynthetic and transpiration rates were such that the intercellular-CO(2) concentration of leaves was largely independent of plant nutrient supply.

Journal Article↗

PubMed2001

Physiological variation among Populus fremontii populations: short- and long-term relationships between delta13C and water availability.

Different populations of widely distributed species can experience dramatically different climatic conditions that may influence physiological activity, specifically carbon assimilation and water use. Populus fremontii Wats. (Fremont cottonwood) populations are found near rivers of varying size along a precipitation gradient from New Mexico to northern California. Climatic differences among populations may lead to physiological differences because P. fremontii is sensitive to water availability. To assess physiological variation among populations, we collected foliage and wood samples from 13 populations that experience different precipitation and stream flow regimes and analyzed the samples for carbon isotope composition (delta13C). Wood delta13C served as a lifetime-averaged indicator of water-use efficiency (WUE), whereas foliage delta13C provided as an estimate of WUE during the growing season of collection. We found approximately 3.4 per thousand variation in delta13C among populations for both foliage (-31.1 to -27.9 per thousand) and wood (-28.3 to -24.7 per thousand). Wood delta13C was, on average, 2.8 per thousand more enriched than foliage. Some of the variation in wood delta13C can be explained by variation in elevation of the study sites. We constructed total precipitation and mean stream flow variables based on the length of the growing season at each study site and analyzed for a relationship between delta13C, precipitation and stream flow. A significant relationship between foliage delta13C and precipitation was found, but water availability did not explain a significant fraction of the variation in wood delta13C. The data suggest that water availability can account for some of the delta13C variation among populations but, given the large residual variances, other factors are important.

California↗