Effects of Particle Abrasion Media and Pressure on Flexural Strength and Bond Strength of Zirconia.

OBJECTIVES: To compare the effects of particle abrasion medium and pressure on shear bond strength and biaxial flexural strength of three generations of zirconia (Lava Frame, Lava Plus, and Lava Esthetic) with the goal of optimizing the bond to zirconia. METHODS: 280 discs (14 mm diameter; 1 mm thickness) of each zirconia were milled and sintered. Specimens of each material were randomly distributed into 14 groups (n=20); half were tested for shear bond strength and half were tested for biaxial flexural strength. The specimens were particle abraded on one surface by 2 different media (50 µm alumina particles or 50 µm glass beads) for 10 seconds at three different pressures (15, 30, and 45 psi or 0.1, 0.2, 0.3 MPa). Untreated specimens served as positive control. A tube (1.50 mm diameter) filled with dual cured resin cement (Panavia SA) was placed onto the surface and light cured. Specimens were stored in water (37°C for 24 hours) and shear bond strength was measured in a universal testing machine (Instron). Biaxial flexural strength of each specimen was measured according to ISO 6872. Shear bond strength and biaxial flexural strength were compared individually with a 2-way analysis of variance (ANOVA) for factors surface treatment and zirconia composition. RESULTS: Significant differences were seen between surface treatments (p<0.01), zirconia composition (p<0.01) and their interaction (p<0.01) for both bond strength and flexural strength. With alumina particle abrasion, higher pressure produced higher bonds for Lava Frame and Lava Plus zirconia while the bond of Lava Esthetic declined with increased pressure. Higher pressure (>0.2 MPa or 30 psi) with alumina decreased biaxial flexural strength with Lava Esthetic zirconia. CONCLUSIONS: Particle abrasion with alumina produced a significantly better combination of bond strength while maintaining biaxial strength of three zirconia materials than particle abrasion with glass beads. The bond strength also depended upon the pressure of particle abrasion and the generation of zirconia used.

Hot tea and tiny tots don't mix: A cross-sectional survey on hot beverage scalds.

OBJECTIVE: Hot beverage scalds are a leading cause of burns in young children. The aim of this study was to look at the circumstances surrounding these injuries in terms of setting, mechanism, supervision and first aid to inform a prevention campaign. METHODS: A cross-sectional study was delivered via iPad to parents and caregivers presenting with a child aged 0-36 months with a hot beverage scald at a major paediatric burns centre. RESULTS: Of the 101 children aged 0-36 months that presented with a hot beverage scald over a 12-month period, 54 participants were included. The scald aetiology was as expected with the peak prevalence in children aged 6-24 months, pulling a cup of hot liquid down over themselves. The majority of injuries occurred in the child's home and were witnessed by the caregiver or parent. The supervising adult was often in close proximity when the scald occurred. Less than a third (28%) of participants received recommended first aid treatment at the scene, with an additional 18% receiving this treatment with three hours of the injury-usually at an emergency department. CONCLUSIONS: While the aetiology of these scalds were as expected, the low use of recommended burn first aid was of concern. Although supervision was present in almost all cases, with the parent/caregiver close-by, this proximity still permitted injury. Attentiveness and continuity of supervision, which can be difficult with competing parental demands, appear to play a more important role role; as do considerations of other safety mechanisms such as hazard reduction through keeping hot drinks out of reach and engineering factors such as improved cup design. By incorporating the findings from this study and other research into a hot beverage scald prevention campaign, we hope to see a change in knowledge and behaviour in parents and caregivers of young children, and ultimately a reduction in the incidence of hot beverage scalds.

Temporal trends in thyroid-stimulating hormone (TSH) and thyroid peroxidase antibody (ATPO) testing across two phases of iodine fortification in Tasmania (1995-2013).

CONTEXT: Tasmania is an island state of the Australian Commonwealth with a well-documented history of mild iodine deficiency. Between 2001 and 2009, Tasmania experienced two incremental phases of iodine fortification. OBJECTIVE: To examine trends in thyroid-stimulating hormone (TSH) and thyroid peroxidase antibody (ATPO) testing and their relationship to different phases of iodine nutrition in the Tasmanian population between 1995 and 2013. DESIGN: Retrospective longitudinal study. SETTING AND PARTICIPANTS: The major primary care and largest public hospital pathology providers in Tasmania submitted data for all TSH and ATPO tests performed between 1995 and 2013. Data linkage methodology was used to determine trends in TSH and ATPO testing. RESULTS: A total of 1.66 million TSH assessments, involving 389,910 individual patients, were performed in Tasmania between 1995 and 2013. There was approximately a fourfold increase in the overall rate of TSH testing during this period with the rate of incident TSH assessment remaining relatively stable over the study period. The incidence of overt suppression and elevation of TSH (TSH≤0.1 mIU/L and ≥10 mIU/L) declined 62.3% and 59.7%, respectively, with a trend for increased incidence of borderline TSH elevation ≥4.0 mIU/L. The incidence of thyroid autoimmunity as determined by the proportion of abnormal ATPO results remained stable, with the absolute number of positive test results increasing during the study period. CONCLUSION: Iodine supplementation of this mildly iodine-deficient population was not associated with an obvious increase in incidence of overt thyroid dysfunction or autoimmunity. Whilst the volume of TSH testing increased over the study period, the increase was driven by patients undergoing follow-up TSH assessments.

Omega-3 fatty acid supplementation provides an additional benefit to a low-dust diet in the management of horses with chronic lower airway inflammatory disease.

BACKGROUND: Omega-3 polyunsaturated fatty acid (PUFA) may benefit humans and animals with chronic inflammatory diseases. HYPOTHESIS: Omega-3 PUFA supplementation improves clinical signs, lung function, and airway inflammation in horses with recurrent airway obstruction (RAO) and inflammatory airway disease (IAD). ANIMALS: Eight research horses and 35 client-owned horses. METHODS: A pilot study examined the dose of PUFA that can alter plasma PUFA composition. Then, a randomized, controlled clinical trial was performed in horses with RAO and IAD. Horses were fed a complete pelleted diet with no hay and randomly assigned to 1 of 3 daily treatments for 2 months: 30 or 60 g of the supplement or 30 g of placebo. Clinical signs, lung function, plasma PUFA composition, and bronchoalveolar lavage fluid (BALF) cytology were evaluated. Data were expressed as median (25-75th percentiles). P < .05 was considered significant. RESULTS: Polyunsaturated fatty acid supplementation resulted in increased plasma docosahexaenoic acid (DHA) that peaked at 4 weeks. Clinical improvement was noted in all horses involved in the clinical trial, but the group that received PUFA had greater improvement in clinical signs (cough score improved 60%), lung function (respiratory effort decreased 48%), and BALF (neutrophils decreased from 23 to 9%) when compared to placebo (cough score improved 33%, respiratory effort decreased 27%, BALF neutrophils increased from 11 to 17%; P < .05). CONCLUSIONS AND CLINICAL IMPORTANCE: Feeding horses with RAO and IAD a PUFA supplement containing 1.5-3 g DHA for 2 months provides an additional benefit to low-dust diet.

Vitamin E nanoemulsions characterization and analysis.

The aims of this work were to characterize vitamin E/canola oil nanoemulsions and to develop a practical RP-HPLC method for vitamin E acetate estimation in the canola oil nanoemulsions. Currently available methods to analyze vitamin E in lipid-emulsions are time-consuming and do not allow adequate separation of vitamin E and its esters. The nanoemulsions were characterized for partition coefficient between emulsion phases, drug loading, free drug, micellar solubilization, encapsulation efficiency and vitamin E concentration in the emulsion external aqueous phase as a function of time. Formulation stability under stress conditions was also evaluated. The nanoemulsions were stable during the test period at 25 and 32 °C with no significant change in mean droplet diameter. The results suggest that prolonged release of lipophilic drugs can be achieved using nanoemulsions. The RP-HPLC method developed showed linearity, selectivity and efficiency. To the best of our knowledge, this is the first practical method for vitamin E analysis in lipid-emulsions. This method may also be applied to the analysis of vitamin E and its esters in other lipid formulations, and for quality control purposes.

The Army Primary Health Care Service: from foundation to future.

Following the British Government's implementation of policies to improve quality and introduce clinical governance into healthcare delivery in the late 1990s, the British Army commissioned a study into how primary healthcare for the Regular Army should best be delivered in UK. The study recommended a unitary command structure, with more central control based upon a model of a main headquarters and seven regions. The change has been largely successful and has been subject to external scrutiny. Areas still to be developed include improving information management and benchmarking standards against the NHS, improvements in practice management, plus developments in occupational health and the nursing cadres. The forthcoming Strategic Defence and Security Review and other ongoing studies are likely to have a profound influence on how the current Army Primary Health Care Service develops.

Effects of natural (RRR alpha-tocopherol acetate) or synthetic (all-rac alpha-tocopherol acetate) vitamin E supplementation on reproductive efficiency in beef cows.

The objective was to determine the effects of natural- or synthetic-source vitamin E on reproductive efficiency in Angus-cross beef cows. In Exp. 1, one hundred fifty-two cows were fed hay and corn silage based diet and assigned to 1 of 3 dietary supplements (3 pens/treatment): 1) containing no additional vitamin E (CON), 2) formulated to provide 1,000 IU x d(-1) of synthetic-source vitamin E (SYN; all-rac or dl-alpha-tocopherol acetate), or 3) formulated to provide 1,000 IU x d(-1) of natural-source vitamin E (NAT; RRR or D-alpha-tocopherol acetate). In Exp. 2, seventy-five cows (2 reps/treatment) were assigned to similar treatments as Exp. 1; however, a vitamin-mineral supplement was offered for ad libitum intake and vitamin intake was calculated from predicted mineral intakes. Cows grazed pastures rather than being fed hay and corn silage as in Exp. 1. In Exp. 1 and 2, supplementation began 6 wk prepartum and continued until initiation of the breeding season. Blood samples were collected at calving (Exp. 1) or breeding (Exp. 2) to determine alpha-tocopherol concentration and weekly beginning 4 wk postpartum (Exp. 1) or 7 and 14 d before estrus synchronization (Exp. 2) to determine return to estrus via progesterone concentration. Cows were synchronized and bred by AI based on heat detection; nonresponding cows were time bred (AI) 66 h after PGF(2 alpha) injection, and cows returning to estrus after AI were bred by natural service. In Exp. 1, cows supplemented with NAT and SYN had greater (P < 0.001) serum concentrations of alpha-tocopherol at calving compared with CON cows. Dietary supplement did not affect (P >or= 0.55) the percentage of cows cycling before synchronization or the number of days to return to estrus by cows that resumed estrus before synchronization. Cows supplemented with SYN tended to have greater first service conception rates compared with CON and NAT (P = 0.09); however, first plus second services combined and overall conception rates were not affected (P >or= 0.23). In Exp. 2, NAT cows had greater (P = 0.002) concentrations of alpha-tocopherol at breeding, whereas there was no difference (P > 0.05) between SYN and CON. Supplementation of SYN or NAT did not affect (P >or= 0.17) days to resumption of estrus before breeding, first service, first plus second services combined, or overall conception rates. These data suggest that supplementation of SYN or NAT source vitamin E increased alpha-tocopherol concentration in cows; however, effects on reproductive efficiency are minimal.

Effects of maternal natural (RRR alpha-tocopherol acetate) or synthetic (all-rac alpha-tocopherol acetate) vitamin E supplementation on suckling calf performance, colostrum immunoglobulin G, and immune function.

The objective of this study was to determine the effects of maternally supplemented natural- or synthetic-source vitamin E on suckling calf performance and immune response. In a 2-yr study, one hundred fifty-two 2- and 3-yr-old, spring-calving, Angus-cross beef cows were blocked by age, BW, and BCS into 1 of 3 isocaloric, corn-based dietary supplements containing 1) no additional vitamin E (CON), 2) 1,000 IU/d of synthetic-source vitamin E (SYN), or 3) 1,000 IU/d of natural-source vitamin E (NAT). Maternal supplementation began approximately 6 wk prepartum and continued until the breeding season. Colostrum from cows and blood from calves was collected 24 h postpartum for analysis of IgG concentration as an indicator of passive transfer and circulating alpha-tocopherol concentration. At 19 d of age, blood was collected from calves to determine the expression of CD14 and CD18 molecules on leukocytes. At 21 and 35 d of age, humoral immune response was measured by a subcutaneous injection, in the neck, with ovalbumin (20 mg; OVA) and blood samples collected weekly until d 63 of age to determine antibodies produced against OVA. At d 63 of age, calves were administered an intradermal injection of OVA (1 mg) in the neck to assess cell-mediated immunity, which was determined on d 65 of age by measuring nodule size with calipers. Circulating alpha-tocopherol concentrations were increased at both 24 h (P = 0.001) and at the day of initial OVA challenge (P < 0.001) in SYN and NAT compared with CON calves. No differences were detected (P > 0.05) for calf birth BW, ADG, or weaning BW. There were no differences (P > 0.05) in calf serum total IgG or cow colostrum total IgG at 24 h or presence of CD14 and CD18 receptors at d 19 of age. The NAT calves had a greater antigen response to OVA at d 63 than SYN calves (P = 0.01; treatment x day interaction). As an indicator of cell-mediated immunity to OVA, nodule size at 65 d of age was not affected (P = 0.92) by maternal dietary supplementation. In conclusion, calves suckling cows supplemented with natural- and synthetic-source vitamin E had increased circulating concentrations of alpha-tocopherol at 24 h, which appeared to continue throughout maternal supplementation; however, calf immune function and performance were not affected.

Beyond postural drainage and percussion: Airway clearance in people with cystic fibrosis.

BACKGROUND: Evidence indicates that there are no statistically significant differences in effectiveness among the airway clearance techniques (ACTs) of active cycle of breathing, autogenic drainage, positive expiratory pressure (PEP) or oscillating PEP in the short-term, but are there differences in the long-term (one year)? The objective of the study was to demonstrate non-inferiority in the long-term. METHODS: Seventy-five people with cystic fibrosis entered the prospective, randomised controlled trial of these five different ACTs. The primary outcome measure was forced expiratory volume in one second (FEV(1)). Secondary outcome measures included exercise capacity and health related quality of life. RESULTS: Using intention to treat, data were available on 65 subjects at the end of the study period. There were no statistically significant differences among the regimens in the primary outcome measurement of FEV(1) (p=0.35). CONCLUSION: In different countries either one or several airway clearance regimens are used. This study provides evidence in support of current practices.

Feeding conjugated linoleic acid partially recovers carcass quality in pigs fed dried corn distillers grains with solubles.

Dried corn distillers grains with solubles (DDGS) fed to swine may adversely affect carcass quality due to the high concentration of unsaturated fat. Feeding CLA enhances pork quality when unsaturated fat is contained in the diet. The effects of CLA on growth and pork quality were evaluated in pigs fed DDGS. Diets containing 0, 20, or 40% DDGS were fed to pigs beginning 30 d before slaughter. At 10 d before slaughter, one-half of each DDGS treatment group was fed 0.6% CLA or 1% choice white grease. Carcass data, liver- and backfat-samples were collected at slaughter. Longissimus muscle area, 10th-rib back-fat depth, last rib midline backfat depth, LM color, marbling, firmness and drip loss, and bacon collagen content were not altered by DDGS or CLA. Outer layer backfat iodine values were increased (P 0.05) for pigs fed DDGS. Feeding CLA decreased (P

Effect of dietary vitamin E supplementation and feeding period on pork quality.

Feeding increased levels of dietary vitamin E can inhibit lipid oxidation. The aim of this study was to investigate the effect of levels of dietary alpha-tocopherol acetate (VE) and feeding duration on meat quality and lipid oxidation. Eighty-one pigs were allocated to 1 of 3 diets containing 40, 200, or 400 IU of VE/kg of feed, and each diet group was divided into 3 feeding periods (3, 6, or 9 wk). Carcass characteristics and meat quality were evaluated. Oxidative stability of fresh and cooked pork patties and pork chops was determined after chilled or frozen storage. Increasing dietary concentrations of VE did not affect any growth performance parameter. Drip loss, however, decreased (P < 0.05) with increased dietary VE levels. Moreover, an increased duration of VE feeding improved (P < 0.05) pH and drip loss. Less lipid oxidation (P < 0.05) was detected in fresh ground pork from pigs fed greater concentrations of VE after 4 d of storage. A greater (P < 0.05) resistance to oxidation in cooked ground pork was observed in pigs fed 200 or 400 IU of VE/kg at 2 and 6 d of storage. Fresh and cooked pork patty oxidation decreased (P < 0.05) linearly as feeding duration increased from 3 to 9 wk. After 6 mo of freezer storage, lipid oxidation of pork chops from pigs fed 200 or 400 IU of VE/kg was lower (P < 0.05) than for pigs fed 40 IU of VE/kg. Likewise, lipid oxidation of pork chops of pigs fed VE for an extended period of time (6 wk) was lower (P < 0.05) after 9 mo of storage. Fatty acid profiles of neutral lipid fraction of the LM became more unsaturated (P < 0.05) with added VE to the feed. These results indicate an increased intake of dietary VE concentration, and prolonged feeding of VE can improve drip loss and reduce lipid oxidation in ground pork and pork chops. This study suggests that supplementation with 200 IU of VE/kg of feed for 6 wk before market is beneficial in improving lipid stability and pork quality.

Effects of dietary vitamin E and fat supplementation on pork quality.

The effects of dietary vitamin E (VE, alpha-tocopherol acetate) and fat supplementation on growth and carcass quality characteristics, oxidative stability of fresh and cooked pork patty in storage, fatty acid profiles of muscle and adipose tissue, and VE concentrations of plasma, muscle, and adipose tissue were studied. Six hundred pigs were allocated to 1 of 6 diets and fed for 63 d in a 3 x 2 factorial design. The dietary treatments included 3 fat levels (normal corn, high oil corn, high oil corn plus added beef tallow) and 2 levels of VE supplementation (40 IU/kg, normal VE supplementation; and 200 IU/kg, high VE supplementation). At 113 kg of BW, 54 pigs were slaughtered as a subsample to evaluate dietary effects on pork quality. Growth performance and meat quality characteristics did not differ (P > 0.05) among treatment groups. The high level of VE supplementation had a beneficial effect on the oxidative stability of pork as indicated by thiobarbituric acid reactive substance (TBARS) values. Lean tissue had lower (P < 0.05) TBARS in the group fed the high VE than in those fed the normal VE level. The TBARS values differed among storage periods (0 to 6 d) and also between fresh and cooked ground ham. Fat type did not significantly affect total saturated and unsaturated fatty acids proportions in the neutral and polar fraction of muscle. Adding VE acetate led to greater (P < 0.05) monounsaturated and total unsaturated fatty acid proportions in neutral lipids of muscle and adipose tissues. Increasing dietary levels of VE acetate increased the concentration of VE in plasma and muscle. These results indicate that dietary VE acetate supplementation increased (P < 0.05) lipid stability and the VE concentration of muscle.

Biodegradation of crude oil across a wide range of salinities by an extremely halotolerant bacterial consortium MPD-M, immobilized onto polypropylene fibers.

The bacterial consortium MPD-M, isolated from sediment associated with Colombian mangrove roots, was effective in the treatment of hydrocarbons in water with salinities varying from 0 to 180 g L(-1). Where the salinity of the culture medium surpassed 20 g L(-1), its effectiveness increased when the cells were immobilized on polypropylene fibers. Over the range of salinity evaluated, the immobilized cells significantly enhanced the biodegradation rate of crude oil compared with free-living cells, especially with increasing salinity in the culture medium. Contrary to that observed in free cell systems, the bacterial consortium MPD-M was highly stable in immobilized systems and it was not greatly affected by increments in salinity. Biodegradation was evident even at the highest salinity evaluated (180 g L(-1)), where biodegradation was between 4 and 7 times higher with immobilized cells compared to free cells. The biodegradation of pristane (PR) and phytane (PH) and of the aromatic fraction was also increased using cells immobilized on polypropylene fibers.

Macharistol, a new cytotoxic cinnamylphenol from the stems of Machaerium aristulatum.

A new cinnamylphenol, macharistol (1), along with a known pterocarpan, (+)-medicarpin (2), were isolated as cytotoxic constituents from the stems of Machaerium aristulatum. In addition, a known pterocarpan, (+)-maackiain (3), and a known isoflavone, formononetin (4), were identified as inactive constituents. Compound 1 was evaluated in the in vivo hollow fiber assay with KB, Col-2, and hTERT-RPE1 cells and found to be inactive at the highest dose (25 mg/kg body weight) tested.

Evaluation of two self-care treatments for prevention of vaginal candidiasis in women with HIV.

Vaginal candidiasis (VC) is a common concern for women living with HIV infection. The authors evaluated the effectiveness of two self-care approaches to prophylaxis of VC among HIV-infected women, weekly intravaginal application of Lactobacillus acidophilus or weekly intravaginal application of clotrimazole tablets, in a randomized, double-blind, placebo-controlled trial. VC was defined as a vaginal swab positive for Candida species in the presence of signs/symptoms of vaginitis and the absence of a diagnosis of Trichomonas vaginalis or bacterial vaginosis. Thirty-four episodes of VC occurred among 164 women followed for a median of 21 months. The relative risk of experiencing an episode of VC was 0.4 (95% CI = 0.2, 0.9) in the clotrimazole arm and 0.5 (95% CI = 0.2, 1.1) in the Lactobacillus acidophilus arm. The estimated median time to first episode VC was longer for clotrimazole (p = .03, log rank test) and Lactobacillus acidophilus (p = .09, log rank test) compared with placebo. Vaginal yeast infections can be prevented with local therapy. Education about self-care for prophylaxis of VC should be offered to HIV-infected women.

Vertebral deformities and low bone mineral density in adults with cystic fibrosis: a cross-sectional study.

Patients with cystic fibrosis (CF) have low bone mineral density (BMD). The clinical relevance of this is not clearly established. The aim of this study was to determine the prevalence of low BMD and vertebral deformities in CF adults with varied disease severity. One hundred and seven patients (58 men) aged 18-60 years underwent dual-energy X-ray absorptiometry scanning of the lumbar spine and hip, radiology of the spine and biochemical studies. Thirty-eight percent had a Z-score of < -1, with 13% having Z-scores < -2. Seventeen percent had evidence of vertebral deformity on radiography, mostly in the thoracic spine. Thirty-five percent reported past fractures, of which 9% were rib fractures. Percent predicted forced expiratory volume in 1 second (FEV1) and the amount of daily physical activity were positively related to BMD. The number of intravenous antibiotic courses in the previous 5 years was negatively related to BMD. Patients with a history of rib fracture and CF-related diabetes had significantly lower femoral neck BMD (p < 0.02). The median serum 25-hydroxyvitamin D was 28 nmol/l, with 36% of patients having levels below 25 nmol/l despite vitamin D supplementation. Forty-four percent had raised levels of urinary pyridinium crosslinks (NTx). In conclusion, fragility fractures and hypovitaminosis D occur commonly in adult patients with CF. Low BMD occurs in patients with more severe disease and significantly relates to FEV1, infective exacerbations and daily energy expended in physical activity.

Nutrient addition to enhance biological treatment of greywater.

This study compares the chemical oxygen demand (COD) removal and respiration rates of a microbial population treating real and synthetic greywaters dosed with nutrient supplements. The nutrient composition of the real and synthetic greywaters was analysed and the dosing regime for nitrogen, phosphorus and a range of trace metals planned accordingly. The doses consisted of eight single additives (macronutrients and trace metals) to the control greywater and six trace metal additions to C: N : P balanced greywater. The COD removal for the control real and synthetic greywater in lab-scale activated sludge systems (0.038 and 0.286 kg COD kg MLSS(-1) d(-1), respectively) confirmed nutrient limitation and the poor degree of greywater treatment. Nutrient dosing increased the COD removal rate and oxygen uptake rate in many cases. The greatest stimulation of microbial activity was observed with zinc additions to C: N: P balanced real greywater (1.291 kg COD kg MLSS(-1) d(-1) over 30 times the control). Inhibitory effects to various extents were rare and limited mainly to the additions of metals to synthetic greywater. The dominance of chemicals effects was observed on addition of some micronutrients; notably iron and aluminium, metals on which many coagulants for use in biotreatment of other wastewaters are based. The data indicate that the impact of understanding microbial processes and the nutrients required for wastewater treatment can only serve to optimise process efficiency for the proposed treatment of greywater.

Selected mechanical properties of fluoride-releasing restorative materials.

Mechanical properties, diametral tensile strength (DTS) and flexural strength (FS) of six fluoride releasing materials were measured and compared. The samples were prepared and tested according to ISO specifications. The materials included a glass ionomer (Fuji IX), a resin-modified glass ionomer (Photac-Fil), two compomers (F 2000; Dyract AP) and two composites (Solitaire; Tetric Ceram). The tests were performed after the materials were stored in distilled water (DTS) and phosphate buffered saline solution (FS) at 37 degrees C for 24 hours and one week. Fluoride-releasing composite resin had the highest flexural and diametral tensile strengths and were statistically stronger than compomers, followed by resin-modified glass ionomer and conventional glass ionomer. However, a notable exception to this general trend was Solitaire, a fluoride-releasing composite resin.

NADH and NADPH-dependent reduction of coenzyme Q at the plasma membrane.

High affinity for NADH, and low affinity for NADPH, for reduction of endogenous coenzyme Q10 (CoQ10) by pig liver plasma membrane is reported in the present work. CoQ reduction in plasma membrane is carried out, in addition to other mechanisms, by plasma membrane coenzyme Q reductase (PMQR). We show that PMQR-catalyzed reduction of CoQ0 by both NADH and NADPH is accompanied by generation of CoQ0 semiquinone radicals in a superoxide-dependent reaction. In the presence of a water-soluble vitamin E homologue, Trolox, this reduction leads to quenching of the Trolox phenoxyl radicals. The involvement of PMQR versus DT-diaphorase under the conditions of vitamin E and selenium sufficiency and deficiency was evaluated for CoQ reduction by plasma membranes. The data presented here suggest that both nucleotides (NADH and NADPH) can be accountable for CoQ reduction by PMQR on the basis of their physiological concentrations within the cell. The enzyme is primarily responsible for CoQ reduction in plasma membrane under normal (nonoxidative stress-associated) conditions.

Protective role of ubiquinone in vitamin E and selenium-deficient plasma membranes.

We have studied the effects of dietary depletion of vitamin E and selenium on endogenous ubiquinone-dependent antioxidant system. Deficiency induced an increase in both coenzyme Q9 and Q10 in liver tissue, reaching a maximum between 4 and 7 weeks of deficient diet consumption. Cytochrome b5 reductase polypeptide was also enriched in membranes after 5 weeks of deficient diet consumption. Substantial DT-diaphorase activity was found in deficient, but not in control plasma membranes. Deficient membranes were very sensitive to lipid peroxidation, although a great protection was observed after incubation with NAD(P)H. Our results show that liver cells can boost endogenous ubiquinone-dependent protective mechanisms in response to deficiency in vitamin E and selenium.