True digestible phosphorus requirement for twenty- to forty-kilogram pigs

The objective of this study was to determine the true digestible P requirements of 20- to 40-kg pigs by the broken-line regression analysis of growth performance using 6 levels of true total-tract digestible P. In Exp. 1, 24 barrows (initial BW=25.2±1.0 kg) were used to determine the true total-tract digestibility (TTTD) of P in monocalcium phosphate using the regression method. The dietary treatments included a corn-soybean meal-based diet (2.96 g total P/kg) and 3 additional dietary treatments with incremental addition of 0.50 g P/kg through monocalcium phosphate. Limestone (37.2% Ca) was added to maintain a constant Ca to P ratio of 1.25 to 1 across all diets. A 5-d adjustment period preceded a 5-d total collection of feces. Ferric oxide was used as a marker to time the initiation and termination of fecal collection. In Exp. 2, 108 barrows and gilts (initial BW=20.1±1.2 kg) were used in a 3-wk growth performance trial. Monocalcium phosphate was added to a corn-soybean meal-based diet to set up 6 levels of TTTD-based digestible P, ranging from 1.31 to 4.64 g/kg of diet with increments of 0.67 g/kg digestible P. Limestone was added to maintain a constant Ca level across all diets. The results of Exp.1 showed that dietary P intake, fecal P output, digested P, and apparent total-tract digestibility of P increased linearly (P<0.05) with the increasing supplementation of monocalcium phosphate. Regressing daily digested P against daily P intake resulted in TTTD of 84.3% for P in monocalcium phosphate. In Exp. 2, ADG, ADFI, and G:F increased both linearly (P<0.01) and quadratically (P<0.05) with increasing P level in wk 1 and 3 and for the overall 3-wk duration. In wk 2, both linear and quadratic effects of P level were observed for ADG and ADFI (P<0.05) whereas the G:F only showed linear improvement (P<0.01). The true digestible P requirement, defined as the breakpoint using the overall 3-wk G:F as the response variable, was estimated to be 3.03, 2.98, and 3.08 g/kg of diet for pigs of mixed sex, barrows, and gilts, respectively. Using ADG, the corresponding estimates of P requirement were 3.09, 3.08, and 3.10 g/kg of diet. In conclusion, the mean true digestible P requirement of pigs from 20 to 40 kg BW was determined to be 3.06 g/kg of diet using the average of the estimates for barrows and gilts based on ADG.

True digestible phosphorus requirement of 10- to 20-kg pigs

The objective of this study was to determine the true digestible P requirement of 10- to 20-kg pigs by broken-line regression analysis of growth performance using 6 levels of true total-tract digestible P. In Exp. 1, 48 barrows were used to determine the true total-tract digestibility (TTTD) of P in monocalcium phosphate using the regression method. The dietary treatments included a negative control (3.30 g/kg total P) and 7 additional dietary treatments with incremental addition of 0.74 g/kg P through monocalcium phosphate, resulting in a dietary range of 3.30 to 8.45 g/kg total P. Limestone was added accordingly to maintain a constant Ca to P ratio of 1.25:1 across all diets. A 5-d adjustment period preceded a 5-d total collection of feces. Ferric oxide was used to time the initiation and termination of fecal collection. In Exp. 2, 108 barrows and gilts were used in a 3-wk growth performance study. Monocalcium phosphate was added to a corn-soybean meal-based diet to set up 6 levels of TTTD-based digestible P, ranging from 1.55 to 4.21 g/kg at an increment of 0.53 g/kg digestible P. Limestone was added accordingly to maintain a constant Ca level across all diets. The results of Exp.1 showed dietary P intake, fecal P output, and digested P increased linearly (P < 0.001) with the increasing P level, whereas the apparent total-tract digestibility of P increased both linearly and quadratically (P < 0.01). The regression of daily digested P against daily P intake gave a TTTD of 67.5% for P in monocalcium phosphate. In Exp. 2, ADG increased linearly (P < 0.001) with the increasing P level in wk 1. In wk 2, wk 3, and the overall 3-wk duration, both linear and quadratic effects of P level (P < 0.05) were observed for ADG. Average daily feed intake increased with the addition of monocalcium phosphate linearly in wk 2 (P < 0.05) and during the overall period (P < 0.001) and both linearly (P < 0.001) and quadratically (P < 0.05) in wk 3. For any period, the G:F was improved in both a linear (P < 0.001) and quadratic (P < 0.05) fashion. The true digestible P requirement, defined as the breakpoint using G:F of the overall duration, was estimated to be 3.22, 2.81, and 3.45 g/kg of diet with dietary DM averaged at 887 g/kg for pigs of mixed sex, barrows, and gilts, respectively. Using ADG, the corresponding P requirement was 3.19, 3.40, and 2.97 g/kg of diet. In conclusion, the true digestible P requirement of pigs from 10 to 20 kg BW was determined to be 3.2 g/kg of diet.

True total-tract digestibility of phosphorus in corn and soybean meal for fifteen-kilogram pigs are additive in corn-soybean meal diet

The objective of this study was to verify the additivity of true total-tract P digestibility (TPD) in corn and soybean meal (SBM) for 15-kg pigs. Fifty-four barrows with an average initial BW of 14.7±1.6 kg were used in a randomized complete block design with a 3×2 factorial arrangement of 6 diets. Three P sources included corn, SBM, and their mixture at a ratio of 2:1. Each P source was provided at low or high level. The diets were fed for a 5-d adjustment period followed by a total collection period of 7 d with ferric oxide as a marker to determine the initiation and termination of fecal collection. The results showed the high P level of each P source increased (P<0.001) P intake, fecal P output, and digested P compared with the low P level. The respective apparent total-tract digestibility of P were 35.66 and 40.57% for low and high P levels in corn, 35.72 and 38.04% for low and high P levels in SBM, and 41.85 and 38.53% for low and high P levels in the corn-soybean meal mixture without significant difference between P levels within P sources. Regressing daily digested P against daily P intake, the TPD was estimated at 40.53, 35.96, and 37.52% for corn, SBM, and their mixture, respectively. The expected TPD in corn and SBM mixture was calculated to be 37.92% based upon the P contribution coefficient calculated to be 0.428 for corn and 0.572 for SBM. The determined TPD (37.52%) in the mixture was not statistically different from the expected (37.92%). In conclusion, the TPD in corn and SBM are additive in corn-soybean meal diet for pigs.

Apparent and standardized ileal digestibilities of amino acids for pigs fed corn- and soybean meal-based diets at varying crude protein levels

The objective of this study was to determine the effect of CP level in corn- and soybean meal-based diets on apparent (AID) and standardized ileal digestibility (SID) of AA. Six pigs (initial BW, 47.1 ± 1.0 kg) fitted with T-cannula at the distal ileum were fed 6 diets for 6 periods in a 6 × 6 Latin square design. The 6 diets consisted of a nitrogen-free diet and 5 corn- and soybean meal-based diets that contained CP of 68, 105, 141, 177, and 214 g/kg. Each period consisted of a 5-d adjustment period and 2 d of ileal digesta collection for 10 h on each of d 6 and 7. The ratio of corn:soybean meal was fixed at 3 to 2 by weight and cornstarch was added to dilute the CP concentration. Chromic oxide was added at 5 g/kg as an indigestible marker. The results showed basal endogenous loss ranged from 65 mg/kg of DMI for Met to 3,104 mg/kg of DMI for Pro. Proline and Gly (1,053 mg/kg of DMI) were the 2 most abundant AA in endogenous flow and together accounted for approximately 43% of the total endogenous AA flow. Of the basal ileal endogenous CP, total AA accounted for 82%. The AID were 80.9 to 84.7%, 85.1 to 87.4%, 72.9 to 79.5%, and 86.5 to 87.9% for Lys, Met, Thr, and Trp, respectively, with corresponding SID being 86.6 to 89.0%, 87.5 to 90.5%, 82.7 to 88.2%, and 90.2 to 94.6%, respectively, as dietary CP increased from 68 to 214 g/kg. There were linear increases in AID of N, Arg, Gly, Ile, Lys, Ser, Thr, Tyr, and Val (P ≤ 0.05) as CP increased and linear decreases in SID of N and all AA measured in this study except Lys, Met, and Pro (P ≤ 0.05). Both linear and quadratic effects were observed in AID for Pro (P < 0.05). In conclusion, the protein content of corn-soybean meal diets evaluated in the current study affected SID of most indispensable and dispensable AA, excluding Lys, Met, and Pro.

Tape stripping on a human nail: quantification of removal

BACKGROUND/PURPOSE

Tape stripping is commonly used to investigate the stratum corneum (SC). This study assesses if protein quantitative tape stripping method was suitable for human nails.

METHOD

We used a colorimetric method to quantify proteins removed by the tape. Water barrier functions as a result of tape stripping were also observed by changes in transonychial water loss (TOWL) from the baseline.

RESULTS

Using tape stripping, we observed no difference between nails in the protein quantity removed by tape stripping (P=0.39). The mean TOWL before and after tape stripping were 6.9 and 9.3 g/m2/h, respectively; this was significantly increased in tape stripped nails (P<0.0001).

CONCLUSION

Tape stripping seems to be an effective method to extract proteins from human nail plate and may aid the study of nail structure and function. Further studies are needed to extend our results in terms of age, gender, ethnicity and disease.

Skin decontamination of glyphosate from human skin in vitro

This study compared three model decontaminant solutions (tap water, isotonic saline, and hypertonic saline) for their ability to remove a model herbicide (glyphosate) from an in vitro human skin model. Human cadaver skin was dosed (approximately 375microg) of [14C]-glyphosate on 3cm2 per skin. After each exposure time (1, 3, and 30min post-dosing, respectively), the surface skin was washed three times (4ml per time) with each solution. After washing, the skin was stripped twice with tape discs. Lastly, the wash solutions, strippings, receptor fluid, and remainder of skin were liquid scintillation analyzer counted to determine the amount of glyphosate. There were no statistical differences among these groups at any time points. The total mass balance recovery at three time exposure points was between 94.8% and 102.4%. The wash off rates (glyphosate in wash solutions) at three different exposure times is 79-101.2%. Thus the three tested decontaminants possess similar effectiveness in removing glyphosate from skin. This in vitro model is not only economic and rapid, but also provides quantitative data that may aid screening for optimal decontaminants.

Percutaneous Penetration Enhancers: An Overview

Transdermal drug delivery is the controlled release of drugs through the skin to obtain therapeutic levels systematically. Several technological advances have been made in the recent decades to enhance percutaneous drug penetration. This overview focuses on the physical, biochemical, and chemical means of penetration enhancement, as well as the classification and mechanisms of chemical penetration enhancers, their application in transdermal drug delivery, and trends and development in penetration enhancement.

In vitro model for decontamination of human skin: Formaldehyde

Decontamination of a chemical from skin is often an emergency measure. This study utilized an in vitro model to compare the decontamination capacity of three model decontaminant solutions (tap water, isotonic saline, and hypertonic saline). Human cadaver skin was dosed (approximately 0.25 microg on 3 cm(2) per skin) with radio-labeled [(14)C]-formaldehyde. After a defined exposure time (1, 3, and 30 min post-dosing, respectively), the surface skin was washed three times (4ml per time) with each solution. After washing, the skin was stripped with tape discs twice. Lastly, the wash solutions, strippings, receptor fluid, and remainder of skin were liquid scintillation analyzer counted to determine the amounts of formaldehyde. Additionally, an evaporation test at different exposure times (1min, 3min, 15min, 30min, and 60min, respectively) was conducted to monitor formaldehyde % evaporation. There were no statistical differences among these groups except isotonic saline, at 3min post-exposure (in wash solutions), showed a significantly difference (p<0.05) when compared to tap water. Formaldehyde % evaporation increased linearly with extending application times, and were 7.7%, 13.6%, 19.7%, 24.4%, and 35.9% (1min, 3min, 15min, 30min, and 60min, respectively). This data suggests that isotonic saline may be effective in removing formaldehyde from skin. However, results from this model need validation in vivo. The model may provide a facile and robust method of accelerating knowledge of decontamination mechanism and lead to enhanced efficacy.

Evaluation of the Antioxidant Capacity and Preventive Effects of a Topical Emulsion and Its Vehicle Control on the Skin Response to UV Exposure

Supplying topical exogenous antioxidants to the skin may prevent or minimize free radical-induced damaging. This study determines antioxidative capacity of a topical skin care emulsion (an oil-in-water vitamin E-containing formulation) versus its vehicle on human skin that was exposed to ultraviolet radiation (UVR) by utilizing a photochemiluminescence device and biophysical methods. Ten healthy Caucasians (3 male and 7 female; mean age 47 +/- 10 years) were enrolled. In a randomized and double-blind manner, a pH-balanced vitamin E emulsion or its vehicle control was applied onto predesignated forearm prior to UVR exposure. Thirty minutes after application, these test sites were exposed to a UV light to induce the minimal erythema dose. One untreated site served as a blank control. Visual scoring and instrumental measurements were recorded at baseline and at 24 h and 48 h thereafter. At day 3, after completing instrumental measurements, each test site was stripped three times in a consecutive manner with a proprietary adhesive tape disc. These tapes were quantified for antioxidant capacity using a photochemiluminescence device. Vitamin E emulsion and vehicle control significantly (p < 0.05) suppressed visual scores when compared with blank control at day 2 and day 3 after UV exposure. However, vitamin E emulsion showed significantly (p < 0.05) lower visual scores when compared with vehicle control at day 2 and day 3 after UV exposure.Also,vitamin E emulsion and its vehicle control significantly (p < 0.05) diminished skin color measurement (a*) values when compared with blank control at day 2 and day 3 after UV exposure. At day 2 after UV exposure, only vitamin E emulsion significantly (p < 0.05) reduced skin blood flow volume when compared with blank control. Vitamin E emulsion and its vehicle control showed significant (p < 0.05) reduction of blood flow volume when compared with blank control at day 3 after UV exposure. Vitamin E emulsion and its vehicle control proved effective in preventing induction of erythema and reducing inflammatory damage caused by UV exposure. The effect of vitamin E emulsion exceeded that of an 'active control'.

Cutaneous bioassay of salicylic acid as a keratolytic

Keratolytic efficacy of topical preparations containing salicylic acid was studied in humans utilizing adhesive tape stripping and quantifying SC removal by protein analysis. In combination with tape stripping, squamometry was used to evaluate the influence of salicylic acid on skin surface scaliness and desquamation. Furthermore, skin barrier perturbation and skin irritancy was recorded and related to the dermatopharmacological effect of the preparations. In contrast to squamometry, tape stripping combined with protein analysis was sensitive in detecting keratolytic effect of salicylic acid within hours of application. Importantly, whereas the pH of the preparations only minimally influenced efficacy, local dermatotoxicity was significantly increased at acidic pH. This indicates that the quest to increase the amount of free, non-dissociated SA is, in fact, counterproductive as the more acidic preparations resulted in skin irritation and barrier disruption.

Hydrating effects of a corticoid oil formulation and its vehicle on human skin

Factors in the treatment of atopic dermatitis include restoring skin moisture and reducing inflammation. This study evaluated a corticoid oil formulation and its components with respect to their skin hydration potential. Ten healthy Caucasians were enrolled. Five test sites on the left and right forearm of each subject were tested: one site served as a normal skin control (without treatment), whereas four were wetted by spraying distilled water (approximately 0.1 ml) over a 3-cm2 skin surface area, and spraying was repeated every 5 min for a total of three applications. Five minutes after the final application, 0.2 ml of the corticoid oil formulation, moisturizing vehicle, and plain peanut oil were applied to each pre-designated site (3 cm2); one site was kept as a blank control (water saturation only). Thirty minutes later, test sites were gently wiped with paper tissues, and visual scoring, transepidermal water loss (TEWL), and capacitance were recorded and repeated at 2 and 3 h. The corticoid oil formulation, plain peanut oil, and moisturizing vehicle significantly increased skin hydration 30 min after each single application, with no statistically significant difference among the treatments at any point. The corticoid oil formulation and plain peanut oil slightly but not significantly elevated TEWL 30 min after application. The results support intuitive dermatologic judgment of advising patients to apply moisturizing medicaments after bathing.

Provocative use test of nickel coins in nickel-sensitized subjects and controls

BACKGROUND

Consensus exists on levels of nickel release that are well tolerated in exposure to nickel-containing items in direct and continuous contact with skin (e.g. watches). The clinical relevance of nickel-containing coins eliciting nickel dermatitis associated with extensive occupational exposure (e.g. coins handled by cashiers) has not been determined.

OBJECTIVES

To examine whether nickel-containing coins might be an elicitor of allergic contact dermatitis (ACD) in occupational settings with extensive exposure to coins (i.e. cashiers).

METHODS

Eighteen subjects (10 nickel sensitized and eight non-nickel sensitized) completed this study after screening of history, physical examination and diagnostic patch testing (5% nickel sulphate). Each volunteer handled 10 coins (nickel-containing coins or non-nickel-containing coins) in a cross-over design at 5-min intervals (5 min handling followed by 5 min rest) for 8 h per day, for a total of 12 days excluding the weekend. One hand was gloved while the other was not during coin handling. Visual scoring and bioengineering measurements were recorded at each of four predetermined sites at baseline (day 1), end of day 5 and day 12 (last day of exposure).

RESULTS

There were no statistical differences for either visual or bioengineering data comparing: (i) nickel-sensitized vs. non-nickel-sensitized subjects handling nickel-containing coins at day 1, day 5 and day 12; (ii) day 12 vs. day 1 (baseline) for nickel-sensitized subjects handling nickel-containing coins; (iii) handling of nickel-containing coins vs. non-nickel-containing coins by nickel-sensitized subjects at day 5 and day 12; (iv) gloved hand vs. ungloved hand of nickel-sensitized subjects handling nickel-containing coins at day 12. Limitations of the method and clinical extrapolation are detailed.

CONCLUSIONS

Individuals handling these nickel-containing coins daily did not develop ACD, as judged by visual signs or bioengineering parameters.

Multidrug-resistance-associated protein MGr1-Ag is identical to the human 37-kDa laminin receptor precursor

We report the isolation and functional characterization of the gene encoding MGr1-Ag, a multidrug-resistance-associated protein. A lambdagt11 cDNA library derived from colorectal carcinoma SW480 cells was screened with monoclonal antibody MGr1. DNA homology analysis of 22 positive clones (designated R1-R22) suggested human 37-kDa laminin receptor precursor (37LRP, R7/R9/R15/R16/R19/R20) and a novel gene (R22) as candidate genes encoding MGr1-Ag. Western blot analysis showed that anti-R20 serum reacted with a unique protein band that was consistent with MGr1-Ag, while anti-R22 serum could not react with MGr1-Ag. The coding gene for MGr1-Ag was amplified using reverse transcription-PCR. Sequence analysis revealed that the MGr1-Ag and 37LRP genes shared the same coding sequence. An in vitro drug sensitivity assay indicated that down-regulation of 37LRP by an antisense technique could significantly enhance the cytotoxicity of anticancer drugs to gastric cancer cells. Thus we draw the conclusion that MGr1-Ag is identical to 37LRP.

Barrier creams - skin protectants: can you protect skin?

Barrier creams (BC) are used in hand care to protect the user against damage from surfactants and other irritants; their clinical value remains debatable; some reports indicate that inappropriate BC application might induce a deleterious rather than a beneficial effect. Since many cosmetic formulations contain 'skin protectants', we review concept, application, and efficacy from the pertinent scientific literature.