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PubMed1998

Chlorophyll a availability affects psbA translation and D1 precursor processing in vivo in Synechocystis sp. PCC 6803.

Transcript accumulation and translation of psbA as well as processing of the D1 precursor protein were investigated in relation to chlorophyll availability in vivo in cyanobacterial strains lacking photosystem I (PS I). The psbA transcript level was almost independent of chlorophyll availability and was approximately 3-fold lower in darkness than in continuous light (5 microE m-2 s-1). Upon illumination, it reached a steady-state level within several hours. Upon growth under light-activated heterotrophic growth conditions (LAHG) in the PS I-less strain, D1 synthesis occurred immediately upon illumination. However, in PS I-less/chlL- cells, which lacked the light-independent chlorophyll biosynthesis pathway and had very low chlorophyll levels after LAHG growth, very little D1 synthesis occurred upon illumination, and the synthesis rate increased with time. This result suggests a translational control of D1 biosynthesis related to chlorophyll availability. Upon illumination, initially a high level of the nonprocessed D1 precursor was observed by pulse labeling and immunodetection in LAHG-grown PS I-less/chlL- cells but not in PS I-less cells. A significant amount of the D1 precursor eventually was processed to mature D1, and the half-life of the D1 precursor decreased as the chlorophyll content of the cells increased. The D1 processing enzyme CtpA was found to be present at similar levels regardless illumination or chlorophyll levels. We conclude that, directly or indirectly, chlorophyll availability is needed for D1 translation as well as for efficient processing of the D1 precursor.

Blotting, Western↗

PubMed1976

An improved procedure for the assay of available lysine and methionine in feedstuffs using Tetrahymena pyriformis W.

1. A study was made of the assay of available lysine and available methionine using Tetrahymena pyriformis W, as applied to a variety of protein-rich feedstuffs. 2. Results were strongly influenced by the conditions under which the analyses were done. With most of the test samples predigestion with papain caused a large increase in the values obtained. 3. An improved assay procedure was developed which included enzymic predigestion of the test samples, "all-in" sterilization of the medium constituents, and measurement of growth from extinction values. It gave results for available lysine that were broadly similar to those obtained in growth tests with rats, and in chemical tests by the method of Carpenter (1960). Values for available methionine agreed closely with those obtained in microbiological tests with Streptococcus zymogenes.

Animal Feed↗

PubMed2004

High vitamin D3 requirements in broilers for bone quality and prevention of tibial dyschondroplasia and interactions with dietary calcium, available phosphorus and vitamin A.

1. Two experiments were carried out to investigate responses in performance and bone compositional and structural characteristics in broilers fed diets containing 4 concentrations of vitamin D3 (5, 20, 125 and 250 microg cholecalciferol/kg) at different concentrations of calcium, available phosphorus and vitamin A. 2. In experiment 1, body weight and tibia breaking strength were maximised at 14d with 250 microg vitamin D3/kg, tibia ash was maximised with 125 microg vitamin D3/kg. A high incidence of tibial dyschondroplasia (TD) was decreased to very low levels with 125 microg vitamin D/kg. 3. At 42d, performance and bone characteristics showed no response to vitamin D3 concentrations above 20 microg/kg. 4. Dietary vitamin A within the range 2-4 to 4.5 mg retinol/kg did not show any interaction with vitamin D3 status at either age. 5. In experiment 2, responses to vitamin D3 were strongly influenced by dietary calcium/available phosphorus. With 13 g calcium and 5 g available phosphorus/kg, performance and bone characteristics responded to vitamin D3 concentrations up to 125 microg/kg but more was needed at less optimal concentrations of calcium and available phosphorus. TD incidence was minimised with 250 microg/kg. 6. This study shows that high dietary concentrations of vitamin D3 can prevent TD. It is concluded that the vitamin D3 requirement of broilers up to 14 d of age at optimal dietary calcium and available phosphorus concentrations may be in the range 35 to 50 microg/kg for cortical bone quality and up to 250 microg/kg for prevention of TD. The vitamin D3 requirement for cortical bone quality after 14 d is not higher than 20 microg/kg. These requirements are much higher than earlier estimates and may be related to higher calcium requirements of modern broiler genotypes. Current regulations limiting maximum vitamin D3 concentrations in broiler starter diets may need to be reviewed.

Animals↗

PubMed1987

Interactions between fats of differing chemical content: apparent metabolisable energy values and apparent fat availability.

1. Tallow (A) and rape oil (E) were obtained for evaluation. They were blended in the ratios A95:E5, A90:E10 and A80:E20. The three blends together with the two pure fats were each included at 40, 80 and 120 g/kg into a basal diet. 2. The experimental diets were evaluated for apparent metabolisable energy corrected to zero nitrogen retention (AMEN MJ/kg) and apparent fat availability (g/kg) using 6 replicates of a cage of two male broiler chicks 14 d old and 8 replicates of a cage of one Rhode Island cross cockerel approximately 1 year old. Diets were fed for 72 h then removed for 24 h. This was followed by a 48 h period when food was available ad libitum and a further 24 h of starvation. A total collection of excreta was undertaken each 24 h for the latter 72 h period. 3. Evaluation of AMEN and apparent fat availability for the individual fat blends was achieved through both linear and quadratic regression. 4. Synergism, as demonstrated by a higher determined than calculated AMEN value, was detected with fat blends fed to chicks but not cockerels and only at rates of inclusion beyond 80 g/kg. 5. No consistent differences between AMEN determined through calorimetry or AME determined with reference to apparent fat availability multiplied by fat gross energy were detected.

Animals↗

PubMed1992

Effects of Pointing Rate and Availability of Visual Feedback on Visual and Proprioceptive Components of Prism Adaptation.

While looking through laterally displacing prisms, subjects pointed 60 times straight ahead of their nose at a rate of one complete movement every 2 or 3 s, with visual feedback available early in the pointing movement or delayed until the end of the movement. Sagittal pointing was paced such that movement speed covaried with pointing rate. Aftereffect measures (obtained after every 10 pointing trials) showed that when the limb became visible early in a pointing movement, proprioceptive adaptation was greater than visual, but when visual feedback was delayed until the end of the movement, the reverse was true. This effect occurred only with the 3-s pointing rate, however. With the 2-s pointing rate, adaptation was predominately proprioceptive in nature, regardless of feedback availability. Independent of the availability of visual feedback, visual adaptation developed more quickly with 3-s pointing, whereas proprioceptive adaptation developed more rapidly with 2-s pointing. These results are discussed in terms of a model of perceptual-motor organization in which the direction of coordinative (guidance) linkage between eye-head (visual) and hand-head (proprioceptive) systems (and consequently the locus of discordance registration and adaptive recalibration) is determined jointly by pointing rate and feedback availability. An additional effect of pointing rate is to determine the rate of discordant inputs. Maximal adaptive recalibration occurs when the input (pointing) rate matches the time constant of the adaptive encoder in the guided system.

Journal Article↗

PubMed2005

Neighborhood racial composition and availability of asthma drugs in retail pharmacies.

This study investigated whether there may be differences in the availability of asthma drugs and equipment in retail pharmacies in nonwhite and white neighborhoods in the District of Columbia. We conducted a telephone survey of a random sample of 38 retail pharmacies in predominately black or white neighborhoods. No differences in the reported availability of asthma drugs and equipment by neighborhood were found, although there was variability in availability of certain asthma drugs and limited availability of asthma equipment. Low demand was the most frequent reason cited by pharmacists regarding why asthma drugs or equipment were not in stock.

Anti-Asthmatic Agents↗

PubMedDate not supplied

Comparative analysis of influence of promoters and inhibitors on in vitro available iron using two methods.

The investigation was undertaken with the objective of comparing two in vitro techniques, measuring dialyzable iron (method A) and measuring ionizable iron (method B), for iron bioavailability in a model system. The effect of the time of introduction of the additives on the available iron was also determined. FeSO4 solution was used as the reference source of iron, to which a series of enhancers (ascorbic acid, citric acid, maleic acid and tartaric acid) and inhibitors (tannic acid, calcium oxalate, oxalic acid, calcium carbonate and sodium phytate) were added individually at various concentrations, and available iron was estimated. From FeSO4 solution, 0.1% (method A) and 3.9% (method B) of iron was available. The addition of ascorbic acid, citric acid and tartaric acid increased this by 33-50%, 28-57% and 23-90%, respectively, for method A and by 15-89%, 24-78% and 24-93% for method B. Tannic acid, sodium phytate and calcium oxalate exhibited an inhibitory effect irrespective of the concentrations, while oxalic acid and calcium carbonate exhibited a dose-dependent inhibitory pattern. The iron availability analyzed by both methods showed a positive correlation with seven out of nine additives. An inverse relation was seen between the inhibitory effect of calcium carbonate and calcium oxalate and their time of introduction into the system. The overall observations showed that although absolute values varied widely, a positive correlation existed between the methods.

Ascorbic Acid↗

PubMed1999

Carbohydrate availability of arroz caldo with lambda-carrageenan.

Total available carbohydrate (sugars and starches) and total dietary fiber (soluble and insoluble) make up the total carbohydrate content of a food. Soluble fiber decreases the availability of glucose by delaying its absorption in the proximal small intestine, thus reducing the postprandial glucose levels (Jenkins et al., 1978; Schneeman, 1987a). Carrageenan, a seaweed extract, is a good source of soluble fiber (Montaño et al., 1985). This study aimed to determine the effect of carrageenan incorporation into arroz caldo on carbohydrate availability by monitoring the postprandial blood glucose levels of normal subjects. Control and experimental arroz caldo samples were prepared and subjected to proximate analysis and feeding studies. The total dietary fiber (TDF) content of the experimental (2.03%) was about thrice that of the control (0.68%). Using randomized crossover design, preweighed 55 g available carbohydrate serving portions of control and experimental arroz caldo samples, with 3.45 and 14.84 g TDF, respectively, were fed to ten fasting normal subjects then their postprandial blood glucose levels were determined at 15, 30, 45, 60 and 90 min intervals. Results of the short-term in vivo study showed that the mean postprandial glycaemic responses of subjects after consuming the experimental sample were significantly lower than the levels after consuming the control at 15, 45, and 90 min (P < or = 0.05) and at 30 min (P < or = 0.001). Likewise, the mean glucose area under the curve was significantly lower (P < or = 0.01) after consumption of experimental (69.22 +/- 32.94) arroz caldo than control (147.29 +/- 53.34). The hypoglycaemic effect of carrageenan may prove useful in the prevention and management of metabolic conditions such as diabetes.

Adult↗

PubMed2005

Accessibility and availability of abortion in six European countries.

OBJECTIVES: The accessibility and availability of abortion are a reflection of abortion law and the accessibility and availability of abortion services. Experiences from six European countries with different political, cultural, social and religious backgrounds (the Netherlands, France, Great Britain, Slovenia, Hungary and Turkey) are presented. RESULTS: Abortion laws in Europe range from complete prohibition to complete liberalization of abortion. Some countries demand a waiting period for the procedure, pre-abortion counseling, parental approval for minors, and in the others there are no mandatory requirements. Abortions are generally performed in authorized facilities by gynecologists or general practitioners. Abortion services are easily accessible, in terms of the law, availability of facilities and health insurance coverage of the procedure in the Netherlands, France and Slovenia. Abortion service is less accessible in United Kingdom, Hungary and Turkey, as a result of limited accessibility to abortion services or a relatively high abortion fee. In some Eastern European countries there has been a tendency in the last decade to limit the availability and access to abortion. CONCLUSIONS: In Europe abortion is generally well accessible in terms of abortion laws. There are differences in accessibility to abortion services between the countries, and in some countries, also between different areas of the country.

Abortion, Induced↗

PubMed2004

Modulation of glycogen phosphorylase activity affects 5-phosphoribosyl-1-pyrophosphate availability in rat hepatocyte cultures.

The effect of modulation of the rate of glycogenolysis on the availability of 5-phosphoribosyl-1-pyrophosphate (PRPP) was investigated in rat hepatocyte cultures. Dibutyryl cyclic AMP (dbcAMP), forskolin and glucagon, activating glycogen phosphorylase through activation of protein kinase A (PKA), were found to raise PRPP availability by 44%-56%. Arg-vasopressin and phenylephrine, activating glycogen phosphorylase through the phosphoinositide cascade, did not affect PRPP availability. dbcAMP, but not phenylephrine, increased the degradation of pre labeled glycogen by 57%. Caffeine and CP-91149, inhibitors of glycogen phosphorylase, decreased PRPP availability by 33% and 43%, respectively. The finding that induction of glycogenolysis enhances, and inhibition of glycogenolysis decelerates PRPP generation suggests that glycogenolysis is a major contributor to PRPP generation in liver tissue in the basal (postabsorptive) state.

Amides↗

PubMedDate not supplied

The role of energy availability in Mammalian hibernation: a cost-benefit approach.

Hibernation is widely regarded as an adaptation to seasonal energy shortage, but the actual influence of energy availability on hibernation patterns is rarely considered. Here we review literature on the costs and benefits of torpor expression to examine the influence that energy may have on hibernation patterns. We first establish that the dichotomy between food- and fat-storing hibernators coincides with differences in diet rather than body size and show that small or large species pursuing either strategy have considerable potential scope in the amount of torpor needed to survive winter. Torpor expression provides substantial energy savings, which increase the chance of surviving a period of food shortage and emerging with residual energy for early spring reproduction. However, all hibernating mammals periodically arouse to normal body temperatures during hibernation. The function of these arousals has long been speculated to involve recovery from physiological costs accumulated during metabolic depression, and recent physiological studies indicate these costs may include oxidative stress, reduced immunocompetence, and perhaps neuronal tissue damage. Using an optimality approach, we suggest that trade-offs between the benefits of energy conservation and the physiological costs of metabolic depression can explain both why hibernators periodically arouse from torpor and why they should use available energy to minimize the depth and duration of their torpor bouts. On the basis of these trade-offs, we derive a series of testable predictions concerning the relationship between energy availability and torpor expression. We conclude by reviewing the empirical support for these predictions and suggesting new avenues for research on the role of energy availability in mammalian hibernation.

Adipose Tissue↗

PubMed1983

Effects of pH and chelating agents on iron binding by dietary fiber: implications for iron availability.

Iron binding by isolated dietary fiber in the presence of iron ligands was measured. Iron-ligand solutions were mixed with isolated fiber and incubated. Bound and polymerized iron were estimated by centrifugation and ultrafiltration, respectively. Results showed that iron binding varied greatly with ligand used and with pH. Based on these studies, it was predicted that ligands would influence iron availability in the order ascorbate less than citrate = nitrolotriacetic acid less than EDTA. When added to a complex meal containing beef, bread, green beans, and milk, iron availability (measured by an in vitro method) was little affected by fiber, citrate, and ascorbate, but enhanced by nitrolotriacetic acid and EDTA. When added to a semisynthetic meal, fiber, ascorbate, citrate, nitrolotriacetic acid, and EDTA increased iron availability. It appears that the effect of dietary fiber on iron availability is greatly dependent on the ligands present in the meal.

Ascorbic Acid↗

PubMed1998

Tools, information sources, and methods used in deciding on drug availability in HMOs.

The use and importance of specific decision-making tools, information sources, and drug-use management methods in determining drug availability and use in HMOs were studied. A questionnaire was sent to 303 randomly selected HMOs. Respondents were asked to rate their use of each of four formal decision-making tools and its relative importance, as well as the use and importance of eight information sources and 11 methods for managing drug availability and use, on a 5-point scale. The survey response rate was 28%. Approximately half of the respondents reported that their HMOs used decision analysis or multiattribute analysis in deciding on drug availability. If used, these tools were rated as very important. There were significant differences in levels of use by HMO type, membership size, and age. Journal articles and reference books were reported most often as information sources. Retrospective drug-use review was used very often and perceived to be very important in managing drug use. Other management methods were used only occasionally, but the importance placed on these tools when used ranged from moderately to very important. Older organizations used most of the management methods more often than did other HMOs. Decision analysis and multiattribute analysis were the most commonly used tools for deciding on which drugs to make available to HMO members, and reference books and journal articles were the most commonly used information sources. Retrospective and prospective drug-use reviews were the most commonly applied methods for managing HMO members' access to drugs.

Data Collection↗

PubMed2002

Effect of the Bamako-Initiative drug revolving fund on availability and rational use of essential drugs in primary health care facilities in south-east Nigeria.

OBJECTIVES: To compare the level of availability and rational use of drugs in primary health care (PHC) facilities where the Bamako Initiative (BI) drug revolving fund programme has been operational, with PHC centres where the BI-type of drug revolving fund programme is not yet operational. METHODS: The study was undertaken in 21 PHC centres with BI drug revolving funds and 12 PHC centres without BI drug revolving funds, all in Enugu State of Nigeria. Data were collected on the essential and non-essential drugs stocked by the facilities. Drug use was determined through analyses of prescriptions in each health centre. Finally, the proportion of consumers that were able to remember their dosing schedules was determined. FINDINGS: An average of 35.4 essential drugs was available in the BI health centres compared with 15.3 in the non-BI health centres (p < 0.05). The average drug-stock was adequate for 6.3 weeks in the BI health centres, but for 1.1 weeks in non-BI health centres (p < 0.05). More injections (64.7 vs. 25.6%) and more antibiotics (72.8 vs. 38%) were prescribed in BI health centres than in the non-BI health centres (p < 0.05). The BI health centres had an average of 5.3 drugs per prescription against 2.1 in the non-BI health centres. However, the drugs prescribed by generic name and from the essential drug list were higher in the BI health centres (80 and 93%) than the non-BI health centres (15.5 and 21%, respectively) (p < 0.05). CONCLUSION: It was observed that the BI facilities had a better availability of essential drugs both in number and in average stock. However, the BI has given rise to more drug prescribing, which could be irrational. The findings call for strategies to ensure more availability of essential drugs especially in the non-BI PHC centres as a strategy to decrease medical costs and improve the quality of PHC services, while promoting rational drug use in all PHC centres. More detailed studies (for example, by focus group discussion or structured interviews) should be undertaken to find out reasons for the over-prescription and to develop future interventions to correct this.

Developing Countries↗

PubMed2005

Availability, distribution and use of emergency obstetric care in northern Tanzania.

The objective of this study is to determine the availability, distribution and quality of facilities providing delivery services, as well as their use by pregnant women. The study is a survey of all facilities providing delivery services (n = 129) in six districts in northern Tanzania. The framework provided by the UNICEF/UNFPA/WHO (UN) Guidelines is applied. An attempt is made to answer the first three questions in this audit outline: are there enough emergency obstetric care (EmOC) facilities? Are they well distributed? And are enough women using them? The results show that there is a very low availability of basic emergency obstetric care (BEmOC) units (1.6/500,000), and a relatively high availability of comprehensive emergency obstetric care (CEmOC) units (4.6/500,000), both with large urban/rural variation. The percentage of expected deliveries in EmOC facilities is 36%, compared with the UN Guidelines minimum accepted threshold of 15%. Nevertheless, the distribution shows a much higher utilization in urban districts compared with rural, indicating that mothers have to travel long distances to receive adequate services when in need of them. The paper also discusses the provisional context of the services in terms of level of facilities providing them and their public/private mix. Most facility deliveries are conducted at CEmOC facilities. Pregnant women tend to utilize the services of voluntary agencies to a greater degree than government services in rural areas, while the government services have a higher burden of the workload in urban areas. A majority (86%) of the deliveries occurring in voluntary agency facilities occur in a qualified EmOC facility. Against a backdrop of a large availability of any facility regardless of their emergency obstetric care status (41.9/500,000), this paper argues that given the large number of potential BEmOC facilities, it seems more efficient to shift resources within the BEmOC level, compared with from CEmOC level down to BEmOC level, to improve access to quality services. There is a large potential for quality improvement, in particular at dispensary and health centre levels. We argue that the main barrier to access to quality care is not the mother's ignorance or their ability to get to a facility, but the actual quality of care meeting them at the facility.

Emergency Medical Services↗

PubMed2006

Bactericidal activity of orally available agents against methicillin-resistant Staphylococcus aureus.

BACKGROUND: The recent proliferation of community-acquired (CA) methicillin-resistant Staphylococcus aureus (MRSA) has led to a marked increase in the need for outpatient treatment of MRSA infections. Many oral agents active against MRSA have been available for years, and a paucity of literature compares them, leaving physicians with little guidance for choosing among them. The purpose of the present study was to compare the bactericidal effects of orally available antibiotics against MRSA and to determine whether there were differences in antimicrobial killing activity against CA-MRSA and hospital-acquired (HA) MRSA isolates. METHODS: A total of 12 unique patient MRSA isolates were studied. Six strains were CA, carrying the staphylococcal chromosomal cassette (SCCmec) type IVa, while six were HA and carried SCCmec type II. Time-kill methods were used to study the bactericidal activity of the orally available antimicrobials linezolid, rifampicin, trimethoprim/sulfamethoxazole, clindamycin, minocycline, and moxifloxacin alone and in combination in vitro. RESULTS: Trimethoprim/sulfamethoxazole was rapidly bactericidal resulting in >2 log(10) cfu/mL decrease at 8 h and >3 log(10) cfu/mL decrease at 24 h in vitro. No antibiotic combination exhibited better killing than trimethoprim/sulfamethoxazole alone. Adding rifampicin to trimethoprim/sulfamethoxazole showed a trend towards antagonism in vitro. There were no differences in the bactericidal activity of any antimicrobial or antimicrobial combination against MRSA isolates carrying SCCmec type IVa versus those carrying SCCmec type II. CONCLUSION: Trimethoprim/sulfamethoxazole is rapidly bactericidal against MRSA in vitro when compared with most other orally available antimicrobials. No differences in bactericidal activity were detected when activities against CA-MRSA and HA-MRSA were compared.

Administration, Oral↗

PubMed1977

Effects of oxalic acid on availability of zinc from spinach leaves and zinc sulfate to rats.

Some effects of dietary oxalic acid on availability of zinc from organic and inorganic sources were assessed. Male rats fed zinc-deficient diets with and without added sodium oxalate were orally dosed once with either 65Zn-labeled spinach leaves or 65Zn-labeled zinc sulfate. Spinach plants (Spinacia oleracea, var. "Winter Bloomsdale") were grown in 65Zn-labeled nutrient solutions that contained 0.033, 0.131 or 0.262 ppm zinc. Increasing zinc supply to the plants increased zinc concentration in the leaves. Oxalic acid content in all leaves was about 7% dry weight. Dietary oxalate enhanced the availability of 65Zn from zinc sulfate, but had no effect on absorption and retention of 65Zn from spinach leaves. Regardless of dietary oxalate levels, absorption and retention of 65Zn was greater from spinach leaves than from zinc sulfate. We concluded that endogenous zinc in spinach leaves was readily available to zinc-deficient rats, and that dietary oxalate was not deleterious to zinc availability.

Absorption↗

PubMed2003

Plant growth-promoting bacteria and nitrate availability: impacts on root development and nitrate uptake.

Plant growth-promoting bacteria (PGPB) and NO-3 availability both affect NO-3 uptake and root architecture. The presence of external NO-3 induces the expression of NO-3 transporter genes and elicits lateral root elongation in the part of the root system exposed to the NO-3 supply. By contrast, an increase in NO-3 supply leads to a higher plant N status (low N demand), which represses both the NO-3 transporters and lateral root development. The effects of PGPB on NO-3 uptake and root development are similar to those of low NO-3 availability (concomitant stimulation of NO-3 uptake rate and lateral root development). The mechanisms responsible for the localized and long-distance regulation of NO-3 uptake and root development by NO-3 availability are beginning to be elucidated. By contrast, the signalling and transduction pathways elicited by the rhizobacteria remain totally unknown. This review will compare the effects of NO-3 availability and PGPB on root morphogenesis and NO-3 uptake, in order to determine whether interactions exist between the NO-3-dependent and the PGPB-dependent regulatory pathways.

Bacteria↗