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PubMed1991

Effects of copper sources and dietary cation-anion balance on copper availability and acid-base status in dairy calves.

Twenty-four Holstein and Jersey calves (14 Holstein), 4 to 11 d of age, were assigned randomly to six treatments in a 2 x 3 factorial arrangement to examine the effects of Cu sources and dietary cation-anion balance on Cu availability and acid-base balance. Treatments were cationic basal diet (20 meq of dietary cation-anion balance on a DM basis), cationic basal diet supplemented with CuO, cationic basal diet supplemented with CuSO4, anionic basal diet (-10 meq), anionic basal diet supplemented with CuO, and anionic basal diet supplemented with CuSO4. Copper sources did not show any effect on growth of calves. The cationic diet increased calf growth compared with the anionic diet at wk 12 of the experiment. Blood pH was increased by the cationic diet in comparison with the anionic diet at wk 8 and 12. Blood pH also was increased by CuSO4 compared with CuO treatment in the early period of the treatment. Blood bicarbonate concentration was decreased by CuO and the anionic diet. Interactions between Cu sources and cation-anion balance were found for blood pH and bicarbonate concentration. Liver Cu concentration was increased by CuSO4 but not by CuO supplementation compared with control. Therefore, CuSO4 was found to be highly available, whereas CuO was a very poorly available source of Cu for young calves.

Acid-Base Equilibrium↗

PubMed1998

Estimating the available energy content of feeds for dairy cattle.

The available energy content of feeds must be known before diets can be formulated, but the difficulty in measuring energy availability requires that estimated values be used. Based on production data, the current system using net energy for lactation (NEL) or total digestible nutrients (TDN) over-valued the energy in feeds by 7 to 8%. A standard discount of 8 TDN units was used for both NEL and TDN. When the discount was calculated from actual intake (4 units per increment of maintenance), feed values for NEL and TDN were overestimated by 5 to 6%. Most feed values for NEL and TDN are estimated from acid detergent fiber. These models do not account for all sources of variation in digestibility, do not allow for variable discounts based on intake and associative effects, and are specific for a given population. Mechanistic models account for many sources of variation and can be modified to include variable discounts based on digestion and passage kinetics. The equation used to convert TDN to NEL does not consider the source of the digestible energy. The NEL of the fat that is contained within feeds is under-valued, and fiber is probably overvalued. Single-component equations are not adequate to describe the complex processes that determine energy availability. The current NEL and TDN systems overvalue the energy in feeds, but both systems still work remarkably well. These systems need to be modified to improve accuracy, but they should not be discarded.

Animal Feed↗

PubMed1980

Variation in the biological availability of xanthophyll within and among generic sources.

Xanthophyll depleted, fasted broilers were intubated with various xanthophyll sources in a series of six experiments. The increase in serum xanthophyll per milligram xanthophyll intubated per kilogram body weight was used to estimate exahtnophyll availability. Statistically significant differences among samples within and among generic sources were obtained. As a result, beta-apo-8'-carotenoic acid ethyl ester (apo-EE) was used as a reference standard in Experiments 4 to 6. When the availability of apo-EE was given a relative value of 100, the availability of xanthophyll from corn gluten meal ranged from 47.7 to 89.1% (four samples), from dehydrated alfalfa, 34.6 to 65.4% (eight samples), and from Coastal Bermudagrass, 18.8 to 27.9% (three samples).

Animal Feed↗

PubMed1984

Biological availability of manganese sources and effects of high dietary manganese on tissue mineral composition of broiler-type chicks.

An experiment was conducted with male broiler-type chicks to study tissue uptake of Mn as a measure of biological availability of Mn sources. A basal corn-soybean meal diet (116 ppm Mn) was supplemented with 0, 1000, 2000, or 4000 ppm Mn as either reagent grade sulfate, carbonate, or monoxide and fed ad libitum for 26 days. No toxic effects were noted as expressed by feed intake, weight gain, feed conversion, hematocrit, hemoglobin, or mortality. Analysis of Mn in tissues revealed a highly linear relationship between liver or bone Mn concentration and dietary Mn for all three sources. Manganese concentration in all tissues increased (P less than .01) as dietary Mn increased. Liver and bone Mn accumulation appeared to be excellent indicators of relative biological availability. On the basis of tissue uptake and solubility tests, MnSO4 X H2O was the most available, followed by MnO and MnCO3, respectively. There were no effects of Mn source or level on concentration of Ca, P, Mg, Cu, Zn, or Fe in tissues studied.

Animals↗

PubMed1995

Relative biological availability of manganese from manganese proteinate, manganese sulfate, and manganese monoxide in broilers reared at elevated temperatures.

The relative biological availabilities of Mn from Mn proteinate, MnSO4, and MnO were compared under two different environmental conditions. Commercial broilers were reared in brooder batteries between Days 1 and 21 and fed diets containing 0, 1,000, 2,000, or 3,000 mg supplemental Mn/kg diet. On Day 22, birds were transferred to individual cages in two environmental chambers maintaining the same dietary Mn sources and supplemental levels. The temperature in one chamber cycled between 18 and 23.9 C (thermoneutral, TN), and in the other chamber cycled between 23.9 and 35 C (heat distress, HD). Birds in the HD environment were exposed to 8 h of 23.9 C, 4 h of 23.9 to 35 C, 4 h of 35 C, and 8 h of 35 to 23.9 C. Tibia Mn increased linearly (P < .05) with level of supplementation when measured on Days 22 and 47. Based on ratios of slopes from multiple linear regression analysis of bone Mn on Mn intake from various sources, the biological availabilities of Mn proteinate and MnO relative to MnSO4 (100%) were 120 and 91%, respectively, in 21-d-old chicks. In 49-d-old birds, corresponding relative biological availabilities of Mn from proteinate and oxide were 125 and 83%, respectively, in birds reared under TN, and 145 and 82%, respectively, for HD birds.

Animals↗

PubMed1995

Improving phosphorus availability in soybean meal for broilers by supplemental phytase.

A 21-d experiment was conducted with day-old male broilers (n=840) to evaluate the effectiveness of supplemental phytase for improving the availability of phytate P in soybean meal when varying levels of P were fed. The semi-purified basal diet (.18% phytate P) contained soybean meal as the only protein source. Seven levels of phytase (0, 200, 400, 600, 800, 1,000, and 1,200 U/kg diet) were added to diets formulated to contain .20, .27, or .34% nonphytate P (nP; or .38, .45, and .52% total P, respectively). The desired levels of nP in the three basal P diets were achieved by adding varying amounts of defluorinated phosphate. A 2:1 Ca:total P ratio was maintained in all diets. Body weight gains and feed intake were improved (P < .001) by phytase at all nP levels, but the magnitude of response was greatest at low nP levels, resulting in an nP by phytase interaction (P < .01). Gain:feed was unaffected by phytase addition. A high mortality (35 to 45%) was observed for the .20 and .27% nP diets without added phytase, but this declined to normal levels with the addition of 200 to 400 U phytase/kg diet. Ash percentage of toes and tibia and shear force and stress of tibia increased with added phytase. These responses clearly show that the phytate-bound P in soybean meal was made more available to broilers by microbial phytase, and the total response was related to the phytase and nP/total P levels. Based on the high R2 values for the second order translog equations, BW gain, feed intake, and toe ash percentage were the most sensitive indicators to assess P availability, followed by tibia force and ash percentage. Derived nonlinear and linear equations for BW gain and toe ash percentage at the two lower nP levels were used to calculate P equivalency values of phytase for inorganic P. Using the average function of P released ( gamma ) by microbial phytase ( chi ) derived with nP levels of .20 and .27% for BW gain and toe ash percentage, gamma = 1.120 - 1.102e-.0027chi, 1 g of P could be released with 821 U of phytase. The amount of P released increased with increasing levels of phytase, but the amount of P released per 100 U of phytase decreased. Released P ranged from 31 to 58% of phytate P for 250 to 1,000 U of phytase/kg of diet.

6-Phytase↗

PubMed2002

Biological availability of traffic-related platinum-group elements (palladium, platinum, and rhodium) and other metals to the zebra mussel (Dreissena polymorpha) in water containing road dust.

The uptake and bioaccumulation of 15 road dust metals by the zebra mussel (Dreissena polymorpha) were investigated in laboratory exposure studies with emphasis on the traffic-related platinum-group elements (PGEs) palladium (Pd), platinum (Pt), and rhodium (Rh). The biological availability of the metals may depend on water characteristics, so the mussels were maintained in two types of water: nonchlorinated tap water and humic water of a bog lake, both of which contained dust of a moderately frequented road. After an exposure period of 26 weeks, soft tissues of the mussels were freeze-dried and analyzed for the metals. The metal concentrations in the mussel soft tissue ranged from several hundred micrograms per gram (e.g., for iron [Fe]) to less than 10 ng/g (for PGEs). Metal uptake from the road dust by the mussels was found for the PGEs and silver (Ag), bismuth (Bi), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), Fe, lead (Pb), and antimony (Sb). After maintenance of mussels in road dust-contaminated tap water, bioaccumulation factors (BAF = (C(exposed mussels) - C(control mussels))/C(total metal, water), where c is concentration) decreased in the following order: Cu > Cd > Ag > Pd > Sb > Pb > Fe > Pt > Rh. The biological availability of most metals was enhanced by humic water as compared to tap water. Our results show a hitherto unrecognized high availability of Pd for the mussels. Thus, this metal should be monitored more intensively in the environment to assess its distribution in the biosphere.

Animals↗

PubMed1992

[The effect of additives on the availability of atropine in transdermal therapeutic systems].

The present paper investigates the effect of 13 liquid and semisolid additives on the pharmaceutical availability of atropine from dermal silicone matrices. The hydrophobic additives isopropylmyristate, linseed oil, methylsilicone oil, olive oil, liquid paraffin, the tensides Abil B 8842, Spans 20, 40, 60, Tweens 40 and 80, and the hydrophilic additives polyethylene glycol 200 and 400 were employed for the study. The additives were incorporated into the silicone matrices in the amount of 5%. The paper aimed to replace polyethylene glycol, used in dermal silicone matrices at present, with a different additive. When using liquid or semisolid additives, a 2 to 3.5-fold increase in pharmaceutical availability of atropine in contrast to the control sample was achieved. The highest values of pharmaceutical availability were obtained with the use of isopropylmyristate, polyethylene glycol 400, olive and linseed oils, and Span 20. The paper discusses the effect of the individual additives on the mechanism of release of atropine from silicone matrices.

Administration, Cutaneous↗

PubMed1988

Availability of body magnesium during magnesium deficiency.

Extensive experimental and clinical studies in animals and humans during the past 25 years have yielded considerable data regarding the availability of internal magnesium (Mg) stores for the maintenance of extracellular and critical tissue concentrations of Mg during periods of Mg deprivation. The bulk of body Mg is present in bone and skeletal muscle, and it is these two sites that provide essentially all the available Mg. In the rat, approximately 15% of bone Mg (equivalent to 1.5 mmol/kg body weight) can be lost, whereas less than one tenth of that amount is available from skeletal muscle. In the human, up to 35% of bone Mg can be lost, but the mean loss in extant studies is 18% (equivalent to 1.2 mmol/kg body weight). In contrast to the rat, up to 40% of human skeletal-muscle Mg can be lost with an average loss of 15% (equivalent to 0.45 mmol/kg). In the human, the bone and skeletal-muscle Mg pools can provide an average of 1.7 mmol/kg body weight equivalent to 15% of total body Mg. Release of Mg from these stores appears to depend on the presence of hypomagnesemia which may also result in small, significant and potentially adverse Mg losses from certain vital organs such as the heart, kidney and brain. The liver and other organs appear not to lose Mg despite Mg deprivation although intracellular Mg shifts of importance cannot be ruled out. These data indicate that the body reserve to combat Mg depletion is not designed to protect the extracellular Mg pool and certain critical organs from Mg deficiency. A continuous optimal intake of Mg is needed for good nutrition and health.

Animals↗

PubMed1987

Systemic availability of o,p'-DDD in normal dogs, fasted and fed, and in dogs with hyperadrenocorticism.

The systemic availability of o,p'-DDD was studied in 12 normal dogs and seven dogs with pituitary-dependent hyperadrenocorticism (PDH). The drug was given by mouth at 50 mg kg-1 and plasma o,p'-DDD concentrations were determined by gas-liquid chromatography. First, six normal dogs were given the drug three times at intervals of one week in a Latin square pattern. Systemic drug availability was found to be very poor from intact tablets in fasted dogs, better with pure drug dissolved in maize oil given by stomach tube, and best with ground tablets mixed in oil poured on dog food. Then six normal dogs and five with PDH were given one dose of o,p'-DDD as intact tablets in dog food. Systemic drug availability was good in the normal animals and, for unknown reasons, better in dogs with PDH. The half-time of elimination was shorter in dogs with PDH than in normal ones. There was evidence of a gradual rise in plasma o,p'-DDD concentrations in seven dogs with PDH treated with 25 mg kg-1 every 12 hours for 14 or 20 days. The interaction between food and o,p'-DDD probably contributes to the variation in clinical response of dogs treated with the drug. The efficiency of therapy with o,p'-DDD should be improved considerably by administering the drug with food.

Administration, Oral↗

PubMed1985

The availability of fluoride from NaF and phosphorus supplements.

The availability of fluoride (F) from dicalcium phosphate (DCP), defluorinated phosphate (DFP), and raw rock phosphate (RRP) has been assessed and compared to the availability of F as NaF. Diets containing 50-55 ppm F were fed to lambs and rats and skeletal F retention determined. The relative availability of F in the different phosphate sources measured by this technique compared to that of NaF was about 50% (DCP), 20% (DFP), and 65% (RRP). Digestibility of F in goats fed similar diets was determined in a 4 x 4 Latin Square design experiment and found to be 38% (DCP), 34% (DFP), 65% (RRP), and 75% (NaF).

Animal Feed↗

PubMed1984

Biopharmaceutical investigations of rectal suppositories. Part 1: Pharmaceutical and biological availability of theophylline.

The influence of suppository base and some tensides on the release and resorption of theophylline from model rectal suppositories was investigated in a preliminary way. It was established that the original Bulgarian suppository base Novosup ensures higher pharmaceutical and biological availability of theophylline in comparison with other investigated lipophilic bases. The preliminary inclusion of Tween 80 in Witepsol H 15 increased the pharmaceutical and biological availability of the drug. A linear relationship between the pharmaceutical and biological availability was observed after administration of model suppositories in rabbits.

Animals↗

PubMed1993

[Determination of drug availability from commercial topical formulations with a multilayer membrane model].

Using the multilayer membrane system (MMS) the drug availability of four drugs from commercial topical formulations are determined. It was found that the availability differs when commercial formulations of beta-methasone-17-valerate, hydrocortisone, diclofenac-Na and clotrimazole were studied. It is shown that the drug availability for characterizing topical formulations has to be taken into account. The MMS applied in this study can be used for the determination of this parameter.

Administration, Topical↗

PubMedDate not supplied

Condom availability programs in U.S. schools.

School condom availability programs have been promoted as a promising approach for increasing condom use among students, for reducing the risk of infections with the human immunodeficiency virus and with other sexually transmitted diseases and for preventing unintended pregnancy. Data from a telephone survey of key individuals at school condom programs across the United States suggest that as of January 1995, at least 431 public schools in 50 U.S. school district made condoms available-2.2% of all public high schools and 0.3% of high school districts. In about half of the schools that were surveyed, students obtained more than one condom per student per year, on average, and in 14% students obtained more than six. Students in alternative schools, in smaller schools, in schools that made condoms available in baskets and in schools with health clinics obtained more condoms per student per year than did students in other schools.

Adolescent↗

PubMed1977

The bio-availability of beta-acetyldigoxine alone and combined with aluminum hydroxide and magnesium hydroxide (Alucol).

The bio-availability of Novodigal (beta-acetyldigoxine) alone and applied together with Alucol (aluminum hydroxide, magnesium hydroxide) was studied in six healthy probands. Bio-availability parameters were calculated from the areas under the plasma concentration curves and from the comparison of the blood levels after absorption during steady state. There was no significant difference between the bio-availability of beta-acetyldigoxine alone and that of the combination with Alucol. Thus, beta-acetyldigoxine combined with antacids of the aluminum hydroxide and magnesium hydroxide type can be applied in the same dosage as usual since no decrease of effect has to be apprehended.

Adult↗

PubMedDate not supplied

Impact of a high school condom availability program on sexual attitudes and behaviors.

CONTEXT: While making condoms available in high schools has provoked much debate, evidence on the actual effects of such programs on students' attitudes and behavior is sparse. METHODS: Prior to implementation of a condom availability program in a Los Angeles County high school, 1,945 students in grades 9-12 (98% of eligible students) completed a self-administered anonymous survey on their sexual behavior and on related knowledge and attitudes; one year later, 1,110 students (59% of eligible students) completed a follow-up survey. RESULTS: There was no significant change over time in the percentage of males or females who had ever had vaginal intercourse or who had had vaginal intercourse during the year prior to the survey. The percentage of males who reported using condoms every time they engaged in vaginal intercourse during the past year increased significantly, from 37% to 50%, and the percentage of males who reported condom use at recently initiated first vaginal intercourse increased from 65% to 80%. On the other hand, female respondents showed no significant change in their condom use. The self-reported likelihood of using a condom for vaginal intercourse during the following year did not change significantly for students who had had vaginal intercourse, but it increased dramatically for those who, had never had vaginal intercourse. The students' attitudes toward sex and condom use either remained the same between surveys or changed in a direction favoring less sexual behavior and greater risk prevention. CONCLUSIONS: The condom availability program appears not to have produced an increase in sexual activity among high school students, and it appears to have led to improved condom use among males. The apparent strong effect on students' intention to use condoms and on males' use at first vaginal intercourse suggests that such programs may have a particular impact on the least sexually experienced adolescents.

Adolescent↗

PubMed1994

Childhood immunization availability in primary care practices. Effects of programs providing free vaccines to physicians.

OBJECTIVE: To examine state immunization distribution programs, along with physician practice, training, and attitudinal factors that influence the availability of childhood immunizations in community practices. DESIGN: Multistate survey stratified by rural and urban practice. PARTICIPANTS: Family physicians in community practices in three states that offer free vaccines to physicians for use in Medicaid recipients (n = 287) and three geographically matched states that do not offer free vaccines (n = 266). RESULTS: Physicians practicing in states that offer free vaccines for use in Medicaid populations were more likely to offer immunizations to patients in their practices (92% vs 75%, respectively; P < .001). This difference persisted even after adjusting for other practice variables that are associated with immunization availability. Physicians who did not offer immunizations cited cost factors as the primary reason for not offering this service. Public health departments were used as the referral site for immunization services, but only 59% of the physicians performed follow-up to determine whether patients received immunizations. CONCLUSIONS: State immunization programs that provide vaccines free to physicians are highly associated with practice policies that increase immunization availability.

Child↗

PubMed1999

Impact of same-day screening mammography availability: results of a controlled clinical trial.

BACKGROUND: We conducted a prospective controlled clinical trial in an urban academic general medicine practice to test the effect of same-day mammography availability on adherence to physicians' screening mammography recommendations. PATIENTS AND METHODS: Participants were a consecutive sample of 920 female patients aged 50 years or older who had received a physician's recommendation for screening mammography at an office visit and had no active breast symptoms, history of breast cancer, or a mammogram within the previous 12 months. Women were assigned to same-day screening mammography availability (intervention group) or usual screening mammography scheduling (control group). MAIN OUTCOME MEASURES: Three-, 6-, and 12-month rates of adherence to physicians' recommendations for screening mammography. RESULT: Twenty-six percent of women in the intervention group obtained a same-day screening mammogram. At 3 months, 58% of the women in the intervention group underwent the recommended screening mammography compared with 43% of the women in the control group (P<.001), increasing to 61% and 49% at 6 months (P<.001), and 268 (66%) of 408 vs 287 (56%) of 512 at 12 months (P = .003). The difference between the intervention and control groups 3-month adherence rates was most marked among women aged 65 years or older (58% vs 34%; P<.001), women who were not employed (54% vs 36%; P<.001), and women with a history of having had either no mammograms (39% vs 20%; P = .02) or only 1 to 2 mammograms (57% vs 38%; P<.001) within the last 5 years. CONCLUSIONS: Same-day mammography availability increased 3-, 6-, and 12-month screening mammography adherence rates in this urban academic general medicine practice. The effect was most marked among women aged 65 years or older, women who were not employed, and those who had had fewer than 3 mammograms in the last 5 years. The efficacy of this intervention in other settings still needs to be demonstrated.

Academic Medical Centers↗