Digested bacterial cell powder (DBCP) as a source of reduced-form folates for pigs: use of a trimethoprim-resistant strain and the bioavailability of folates in DBCP.
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The production of digested bacterial cell powder (DBCP) as a source of reduced-form folates for pigs was studied. Trimethoprim-resistant mutants of Brevibacterium lactofermentum ATCC 13869 accumulated a significantly higher amount of the reduced form of folate in the cells than the wild-type strain. DBCPs were prepared from the resistant mutant strain and the wild-type strain. The utilization of the reduced-form of folate in DBCP was evaluated by measuring the plasma folate level after orally administering DBCP to Gottingen minipigs. The folates in both DBCPs proved to have equally high bioavailability in the pigs. (+info)
Application of sintered titanium alloys to metal denture bases: a study of titanium powder sheets for complete denture base.
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The purpose of this study was the fabrication of titanium powder sheets to enable the application of sintered titanium alloys as metal denture bases. The effects of titanium particle shape and size, binder content, and plasticizer content on the surface smoothness, tensile strength and elongation of titanium powder sheets was investigated. To select a suitable ratio of powdered metal contents for application as a metal denture base, the effects of aluminum content in Ti sheets and various other powder metal contents in Ti-Al sheets on the density, sintering shrinkage, and bending strength were evaluated. Based on the results of the above experiments, we developed a mixed powder sheet composed of 83Ti-7Al-10Cr with TA45 titanium powder (atomized, -45 microm), and 8 mass% binder content. This titanium alloy sheet had good formability and ductility. Its sintered titanium alloy had a density of 3.2 g/cm3, sintering shrinkage of 3.8%, and bending strength of 403 MPa. The titanium alloy sheet is clinically acceptable for fabricating denture bases. (+info)
Evaluation of flow properties of dry powder inhalation of salbutamol sulfate with lactose carrier.
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The effects of the flow and packing properties of a drug/carrier powder mixture on emission of drug adhering to the carrier from capsules and inhalation devices were investigated. Model powder mixtures were designed consisting of lactose carriers with different particle shapes were prepared by surface treatment and micronized salbutamol sulfate. These powder mixtures were aerosolized by a Spinhaler, and in vitro deposition properties of salbutamol sulfate were evaluated by a twin impinger. The flow properties of the mixed powders were evaluated by the Carr's flowability index (FI) and Hausner's ratio (HR). The packing properties of the mixed powders were determined employing the tapping method. Compared with the powder mixed with the untreated lactose carrier, the FI, HR, and the constant K in Kawakita's equation of the powder mixture prepared using the surface-treated lactose carrier were significantly different, showing that the flow and packing properties of the drug/carrier powder mixture were improved. Using this surface-treated system, the handling of the powder mixture when packing into capsules is improved, which is desirable for handling dry powder inhalants. The fraction (%) of drug emitted from capsules and devices (EM) and the FI of the powder mixture were correlated. As the flow properties improved, the outflow of the powder mixture from capsules and devices became easier, and emission of drug adhering on the carrier from capsules and devices improved. Improvement of the inhalation process, such as the drug particles emitted from the inhalation system, is valuable for increasing inhalation properties of dry powder inhalation. (+info)
Effects of cocoa powder and dark chocolate on LDL oxidative susceptibility and prostaglandin concentrations in humans.
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BACKGROUND: Flavonoids are polyphenolic compounds of plant origin with antioxidant effects. Flavonoids inhibit LDL oxidation and reduce thrombotic tendency in vitro. Little is known about how cocoa powder and dark chocolate, rich sources of polyphenols, affect these cardiovascular disease risk factors. OBJECTIVE: We evaluated the effects of a diet high in cocoa powder and dark chocolate (CP-DC diet) on LDL oxidative susceptibility, serum total antioxidant capacity, and urinary prostaglandin concentrations. DESIGN: We conducted a randomized, 2-period, crossover study in 23 healthy subjects fed 2 diets: an average American diet (AAD) controlled for fiber, caffeine, and theobromine and an AAD supplemented with 22 g cocoa powder and 16 g dark chocolate (CP-DC diet), providing approximately 466 mg procyanidins/d. RESULTS: LDL oxidation lag time was approximately 8% greater (P = 0.01) after the CP-DC diet than after the AAD. Serum total antioxidant capacity measured by oxygen radical absorbance capacity was approximately 4% greater (P = 0.04) after the CP-DC diet than after the AAD and was positively correlated with LDL oxidation lag time (r = 0.32, P = 0.03). HDL cholesterol was 4% greater after the CP-DC diet (P = 0.02) than after the AAD; however, LDL-HDL ratios were not significantly different. Twenty-four-hour urinary excretion of thromboxane B(2) and 6-keto-prostaglandin F(1)(alpha) and the ratio of the 2 compounds were not significantly different between the 2 diets. CONCLUSION: Cocoa powder and dark chocolate may favorably affect cardiovascular disease risk status by modestly reducing LDL oxidation susceptibility, increasing serum total antioxidant capacity and HDL-cholesterol concentrations, and not adversely affecting prostaglandins. (+info)
Epidermal powder immunization induces both cytotoxic T-lymphocyte and antibody responses to protein antigens of influenza and hepatitis B viruses.
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Cytotoxic T lymphocytes (CTL) play a vital role in host defense against viral and intracellular bacterial infections. However, nonreplicating vaccines administered by intramuscular injection using a syringe and needle elicit predominantly humoral responses and not CTL responses. Here we report that epidermal powder immunization (EPI), a technology that delivers antigens on 1.5- to 2.5-microm gold particles to the epidermis using a needle-free powder delivery system, elicits CTL responses to nonreplicating antigens. Following EPI, a majority of the antigen-coated gold particles were found in the viable epidermis in the histological sections of the target skin. Further studies using transmission electron microscopy revealed the intracellular localization of the gold particles. Many Langerhans cells (LCs) at the vaccination site contained antigen-coated particles, as revealed by two-color immunofluorescence microscopy, and these cells were found in the draining lymph nodes 20 h later. Immune responses to several viral protein antigens after EPI were studied in mice. EPI with hepatitis B surface antigen (HBsAg) and a synthetic peptide of influenza virus nucleoprotein (NP peptide) elicited antigen-specific CTL responses as well as antibody responses. In an in vitro cell depletion experiment, we demonstrated that the CTL activity against HBsAg elicited by EPI was attributed to CD8(+), not CD4(+), T cells. As controls, needle injections of HBsAg or the NP peptide into deeper tissues elicited solely antibody, not CTL, responses. We further demonstrated that EPI with inactivated A/Aichi/68 (H3N2) or A/Sydney/97 (H3N2) influenza virus elicited complete protection against a mouse-adapted A/Aichi/68 virus. In summary, EPI directly delivers protein antigens to the cytosol of the LCs in the skin and elicits both cellular and antibody responses. (+info)
The influence of microcrystalline cellulose grade on shape and shape distributions of pellets produced by extrusion-spheronization.
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In this study, five microcrystalline cellulose (MCC) grades were physically characterized and their extrusion-spheronization behaviours were characterized in terms of water requirements and pellet shape profiles. It was found that the MCC grades differed significantly in the physical properties investigated. Physical properties of MCC were found to influence the water requirement for extrusion-spheronization. MCC grades of higher bulk densities, lower porosities and water retentive capacities required less water to produce pellets of equivalent size. These MCC grades were also found to produce pellets of lower sphericity and wider shape distributions. Packing of MCC particles within the agglomerate played a role in determining amount of water retention and pellet rounding during spheronization. However, there was a limit to the influence of packing density on the rate of pellet rounding because poor packing resulted in higher water retentive capacity, which also limited the rate of rounding. (+info)
Release from or through a wax matrix system. I. Basic release properties of the wax matrix system.
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Release properties from a wax matrix tablet was examined. To obtain basic release properties, the wax matrix tablet was prepared from a physical mixture of drug and wax powder (hydrogenated caster oil) at a fixed mixing ratio. Properties of release from the single flat-faced surface or curved side surface of the wax matrix tablet were examined. The applicability of the square-root time law and of Higuchi equations was confirmed. The release rate constant obtained as g/min(1/2) changed with the release direction. However, the release rate constant obtained as g/cm2 x min(1/2) was almost the same. Hence it was suggested that the release property was almost the same and the wax matrix structure was uniform independent of release surface or direction at a fixed mixing ratio. However, these equations could not explain the entire release process. The applicability of a semilogarithmic equation was not as good compared with the square-root time law or Higuchi equation. However, it was revealed that the semilogarithmic equation was available to simulate the entire release process, even though the fit was somewhat poor. Hence it was suggested that the semilogarithmic equation was sufficient to describe the release process. The release rate constant was varied with release direction. However, these release rate constants were expressed by a function of the effective surface area and initial amount, independent of the release direction. (+info)
Effect of rise in simulated inspiratory flow rate and carrier particle size on powder emptying from dry powder inhalers.
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The purpose of this study was to evaluate the effect of carrier particle size and simulated inspiratory flow increase rate on emptying from dry powder inhalers (DPIs). Several flow rate ramps were created using a computer-generated voltage signal linked to an electronic proportioning valve with a fast response time. Different linear ramps were programmed to reach 30, 60, 90, and 120 L/minute over 1, 2, or 3 seconds. At the lower flow rates, 100-ms and 500-ms ramps were also investigated. Three DPIs, Spinhaler, Rotahaler, and Turbuhaler, were used to test the effect of flow rate ramp on powder emptying. To test the effect of carrier particle size, anhydrous lactose was sieved into 3 particle sizes, and 20 mg of each was introduced into #2 and #3 hard gelatin capsules for Spinhaler and Rotahaler, respectively. Emptying tests were also carried out using the on/off solenoid valve described in the United States Pharmacopeia (USP) (resulting in no ramp generation). Powder emptying increased from 9% to 46% for Rotahaler and 69% to 86% for Spinhaler from the shallowest (3 seconds to reach peak flow) to the 100-ms ramp for the 53- to 75 microm lactose size range at 30 L/minute. Similar trends were observed for larger particle size fractions at the same flow rate. However, at higher airflow rates (60, 90, and 120 L/minute), there was no significant increase in percentage of emptying within the ramps for a particular particle size range. Trends observed were similar for placebo-filled Turbuhaler and commercially available Rotacaps used with Rotahaler, with the steepest ramp demonstrating more complete emptying. Percentage of powder emptying determined by the USP solenoid valve overestimated the emitted dose compared with the ramp method at 30 L/minute for all 3 devices. Results indicate that there is a significant difference in powder emptying at 30 L/minute from the shallowest to the steepest ramp within a particular size range. Within a particular particle size range, the USP method produced more complete emptying than even the steepest ramp, especially at the lower flow rates. Thus, when the USP device is used to estimate DPI emptying at lower flow rates, the results are likely to overestimate DPI performance significantly. (+info)