Does supplementation of vitamin C, reduced glutathione or their association in semen extender reduce oxidative stress in bovine frozen semen? / A suplementação de vitamina C, glutationa reduzida ou sua associação no diluidor de sêmen reduz o estresse oxidativo no sêmen congelado bovino?

The aim of this study was to evaluate the addition of vitamin C, reduced glutathione and the association thereof to the bovine semen cryopreservation extender. The ejaculate from nine bulls were divided into four fractions, each corresponding to a treatment, namely: control group-semen diluted with Tris-yolk extender; vitamin C group-semen diluted in Tris-yolk extender supplemented with vitamin C (2.5mmol/mL); glutathione group-semen diluted in Tris-yolk extender supplemented with reduced glutathione (2.5mmol/mL) and associated group-semen diluted in Tris-yolk extender supplemented with vitamin C (1.25mmol/mL) and reduced glutathione (1.25mmol/mL). Afterwards, the semen was packed into French straws and submitted to cryopreservation using automated equipment. After cryopreservation, the semen was thawed and evaluated considering sperm motility, morphology, plasma membrane, acrosome, mitochondrial potential and oxidative stress, as well as the thermo resistance test. Extender's supplementation with the association of vitamin C and reduced glutathione showed benefic effects on sperm motility and preservation of plasma and acrosomal membranes during semen cryopreservation, being also the group that showed higher values of reactive oxygen species. Thus, the association of both antioxidants contributed to the preservation of sperm cells in every analyzed characteristic, suggesting its use on bovine semen cryopreservation.(AU)

O objetivo deste estudo foi avaliar a adição de vitamina C, glutationa reduzida e sua associação ao diluidor de criopreservação de sêmen bovino. O ejaculado de nove touros foi dividido em quatro frações, cada uma correspondendo a um tratamento, a saber: grupo controle - sêmen diluído em Tris-gema; grupo vitamina C - sêmen diluído em Tris-gema, suplementado com vitamina C (2,5mmol/mL); grupo glutationa - sêmen diluído em Tris-gema, suplementado com glutationa reduzida (2,5mmol/mL) e grupo sêmen associado - diluído em Tris-gema, suplementado com vitamina C (1,25mmol/mL) e glutationa reduzida (1,25mmol/mL ). Posteriormente, o sêmen foi envasado em palhetas francesas e submetido à criopreservação por meio de equipamento automatizado. Após a criopreservação, o sêmen foi descongelado e avaliado quanto à motilidade espermática, à morfologia, à membrana plasmática, ao acrossoma, ao potencial mitocondrial e ao estresse oxidativo, bem como pelo teste de resistência térmica. A suplementação de extensor com a associação de vitamina C e glutationa reduzida mostrou efeitos benéficos sobre a motilidade espermática e a preservação das membranas plasmática e acrossomal durante a criopreservação de sêmen, sendo também o grupo que apresentou maiores valores de espécies reativas de oxigênio. Assim, a associação de ambos os antioxidantes contribuiu para a preservação dos espermatozóides em todas as características analisadas, sugerindo sua utilização na criopreservação de sêmen bovino.(AU)

Supplementation of grazing beef cows during gestation as a strategy to improve skeletal muscle development of the offspring.

The appropriate supply of nutrients in pregnant cows has been associated with the optimal development of foetal tissues, performance of their progeny and their meat quality. The aim of this study was to evaluate supplementation effects of grazing cows in different stages of gestation on skeletal muscle development and performance of the progeny. Thereby, 27 Nellore cows were divided into three groups (n=9 for each group) and their progeny as follows: UNS, unsupplemented during gestation; MID, supplemented from 30 to 180 days of gestation; LATE, supplemented from 181 to 281 days of gestation. The percentage composition of the supplement provided for the matrices was the following: ground corn (26.25%), wheat bran (26.25%) and soya bean meal (47.5%). The supplement was formulated to contain 30% CP. Supplemented matrices received 150 kg of supplement (1 and 1.5 kg/day for cows in the MID and LATE groups, respectively). After birth, a biopsy was performed to obtain samples of skeletal muscle tissue from calves to determine number and size of muscle fibres and for messenger RNA (mRNA) expression analysis. The percentage composition of the supplement provided for the progeny was the following: ground corn grain (30%), wheat bran (30%), soya bean meal (35%) and molasses (5%). The supplement was formulated to contain 25% CP and offered in an amount of 6 g/kg BW. Performance of the progeny was monitored throughout the suckling period. Means were submitted to ANOVA and regression, and UNS, MID and LATE periods of supplementation were compared. Differences were considered at P0.10). Similarly, no differences were observed between calves for nutrient intake (P>0.10). However, greater subcutaneous fat thickness (P=0.006) was observed in the calves of LATE group. The ribeye area (P=0.077) was greater in calves born from supplemented compared with UNS cows. The supplementation of pregnant cows did not affect the muscle fibre size of their progeny (P=0.208). On the other hand, calves born from dams supplemented at mid-gestation had greater muscle fibre number (P=0.093) compared with calves from UNS group. Greater mRNA expression of peroxysome proliferator-activated receptor α (P=0.073) and fibroblast growth factor 2 (P=0.003) was observed in the calves born from MID cows. Although strategic supplementation did not affect the BW of offspring, it did cause changes in carcass traits, number of myofibres, and mRNA expression of a muscle hypertrophy and lipid oxidation markers in skeletal muscle of the offspring.

Análise microbiológia da casca do abacaxi (Ananás comosus) sob diferentes condições de higienização para obtenção de suco e chá / Microbiological analysis of pineapple bark (Ananás comosus) under different hygienic conditions to obtain juice and tea

A casca do abacaxi é um resíduo da agroindústria que pode auxiliar na dieta humana de forma complementar, permitindo sua utilização em alimentos de baixo valor nutricional. Percebendo que a casca do abacaxi é desprezada pelas indústrias de alimentos e devido à grande preocupação global atual de se minimizar os resíduos buscando uma melhoria do meio ambiente e de geração de lucros para empresas, neste estudo teve-se por objetivo avaliar os micro-organismos existentes na casca do abacaxi, antes e após a higienização e sanitização para o preparo de sucos e chás. Na higienização foi utilizada água corrente e na sanitização solução clorada a 200 ppm. Com os dados obtidos concluiu-se que os cuidados com a higienização adequada da casca são importantes, que a lavagem somente com água não é eficaz para a eliminação total dos micro-organismos presentes na casca do abacaxi, já a higienização com solução clorada é amplamente recomendada para retardar ou eliminar o crescimento microbiano.

Natural zeolites in diet or litter of broilers.

This study aims to analyse the influence of adding natural zeolites (clinoptilolite) to the diet or litter of broilers and their effects on growth performance, carcass yield and litter quality. Three consecutive flocks of broilers were raised on the same sawdust litter, from d 1 to d 42 of age, and distributed in three treatments (control with no added zeolites, addition of 5 g/kg zeolite to diet and addition of 100 g/kg zeolites to litter). The addition of zeolites to the diet or litter did not affect growth performance or carcass yield. The addition of zeolites to the diet did not influence moisture content of the litter, ammonia volatilisation was reduced only in the first flock and pH of litter was reduced in the second and third flock. However, the addition of zeolites to the litter reduced moisture content, litter pH and ammonia volatilisation in all flocks analysed. The addition of 5 g/kg zeolite to the diet in three consecutive flocks was not effective in maintaining litter quality, whereas the addition of 100 g/kg natural zeolites to sawdust litter reduced litter moisture and ammonia volatilisation in three consecutive flocks raised on the same litter.

Nutritional evaluation of young bulls on tropical pasture receiving supplements with different protein:carbohydrate ratios.

The objective of this work was to evaluate the nutritional parameters of young bulls supplemented with different ratios of protein: carbohydrate on tropical pastures from 4 until 18 months old. Fifty-five non-castrated beef calves (138.3±3.4 kg, 90 to 150 d of age) were used. The calves (young bulls) were subjected to a 430-d experimental period encompassing 4 seasons. The treatments were as follows: control, only mineral mixture; HPHC, high protein and high carbohydrate supplement; HPLC, high protein and low carbohydrate supplement; LPHC, low protein and high carbohydrate supplement; and LPLC, low protein and low carbohydrate supplement. The amount of supplement was adjusted every 28 d. Dry matter (DM) intake was higher in the dry-to-rainy transition and rainy seasons for all nutritional plans. Non-supplemented animals had lower intakes of DM and total digestible nutrients (TDN) than supplemented young bulls in all seasons. Although differences in DM intake were not observed between supplemented animals, the supplements with high carbohydrate (HPHC and LPHC) had lower forage intake during suckling (rainy-to-dry transition season) and in the rainy season. However, the HPHC treatment animals had higher intake and digestibility of neutral detergent fiber. It can be concluded that supplementation with high protein levels (supplying 50% of the crude protein requirement) provide the best nutritional parameters for grazing young bulls in most seasons, increasing intake and digestibility of diet, and these effects are more intense when associated with high carbohydrate levels level (supplying 30% TDN requirement).

Increasing the added-value of onions as a source of antioxidant flavonoids: a critical review.

Flavonoids are a large and diverse group of polyphenolic compounds with antioxidant effects. While the flavonoid content and composition profile clearly reflect the genetic background of the cultivar, environmental conditions and agronomic practices are also determinants for the composition of crops at harvest. Considerable research has been directed toward understanding the nature of polyphenols in different products and the factors influencing their accumulation. This review examines the flavonoids as a class of compounds, the role these compounds play in the plant, their contributions to product quality, and recent research on the impacts of environmental factors and cultural practices on flavonoid content in onions, highlighting how this knowledge may be used to modulate their polyphenolic composition at harvest or during post-harvest handling.

Aspectos botânicos, químicos, farmacológicos e terapêuticos do Hypericum perforatum L / Botanical, chemical, pharmacological and therapeutic aspects of Hypericum perforatum L

Estima-se que aproximadamente 25% das drogas prescritas em todo o mundo são oriundas de espécies vegetais. Dentre as plantas com alto potencial medicinal, se destaca o Hypericum perforatum L. (HP), planta herbácea perene, pertencente à família Hypericaceae. Extratos orgânicos e aquosos de HP têm sido utilizados na medicina popular e em testes pré-clínicos para o tratamento e prevenção de diversas doenças através de efeitos nefroprotetores, atividades antioxidante, antifúngica, ansiolítica, antiviral e cicatrizante. Estudos clínicos indicaram que esta espécie pode ser útil no tratamento de desordens originadas do sistema nervoso central, especialmente na depressão unipolar. HP contém, ao menos, dez classes de compostos biologicamente ativos, dentre eles antraquinonas/naftodiantronas, derivados de floroglucinol, flavonoides, biflavonas, xantonas, óleos voláteis, aminoácidos, vitamina C, cumarinas, taninos e carotenoides. Ao mesmo tempo em que os constituintes possuem relevantes efeitos farmacológicos, os mesmos podem prejudicar, por antagonismo farmacocinético (interação com algumas enzimas do citocromo), a eficácia de outros fármacos. Devido a relevante importância do HP como agente terapêutico, ressalta-se a importância do desenvolvimento de novos estudos com o intuito de elucidar questões ainda controversas acerca do extrato de HP, e.g., dose, melhor horário para colheita, padronização dos extratos, e possíveis efeitos tóxicos, podendo assim, definir claramente os riscos e benefícios da utilização desta planta.

It is estimated that approximately 25% of prescribed drugs are derived from plant species. Among the plants with high medicinal potential, it highlights the Hypericum perforatum L. (HP), perennial herbaceous plant belonging to the family Hypericaceae. Organic and aqueous extracts of HP have been used in folk medicine and in pre-clinical testing for the treatment and prevention of several diseases through effects nefroprotetores, antioxidant, antifungal, anxiolytic, wound healing and antiviral activities. Clinical studies indicated that this specie can be useful in the treatment of central nervous system disorders, especially to unipolar depression. HP contains at least ten classes of biologically active compounds, including anthraquinones/naftodiantronas, phloroglucinol derivatives, flavonoids, biflavones, xanthones, volatile oils, amino acids, vitamin C, coumarins, carotenoids and tannins. At the same time that the secondary metabolites have important pharmacological effects, they can impair the effectiveness of other drugs by pharmacokinetic antagonism.

Effect of forest fragmentation on microsporogenesis and pollen viability in Eugenia uniflora, a tree native to the Atlantic Forest.

Habitat fragmentation, caused by the expansion of agriculture in natural areas, may be one of the strongest impacts humans have on the ecosystem. These changes can decrease the number of individuals in a population, leading to endogamy. In allogamous species, endogamy can have a negative effect on reproductive capacity. In this study, we analyzed the effects of forest fragmentation on microsporogenesis and pollen viability in Eugenia uniflora L., a tree species native to the Atlantic Forest. We analyzed 4 populations, 3 of which were connected by forest corridors and 1 of which was isolated by agricultural fields on all sides. For microsporogenesis analysis, 9000 meiocytes representing all stages of meiosis were evaluated. To perform the pollen viability test, we evaluated 152,000 pollen grains. Microsporogenesis was stable in plants from populations that were connected by forest corridors (abnormalities, less than 6%), while microsporogenesis in plants from the isolated population showed a higher level of abnormalities (13-29%). Average pollen viability was found to be more than 93% in the non-isolated populations and 82.62% in the isolated population. The χ(2) test showed that, in the isolated population, the meiotic index was significantly lower than that in the non-isolated populations (P = 0.03). The analysis of variance for the percentage of viable pollen grains confirmed the significant difference between the isolated and non-isolated populations. Our data show that forest fragmentation has a direct effect on microsporogenesis and pollen viability in E. uniflora and can directly influence the reproductive capacity of isolated populations of this species.

Microbiota benefits after inulin and partially hydrolized guar gum supplementation: a randomized clinical trial in constipated women.

INTRODUCTION: Prebiotics positively affect gut microbiota composition, thus improving gut function. These properties may be useful for the treatment of constipation. OBJECTIVES: This study assessed the tolerance and effectiveness of a prebiotic inulin/partially hydrolyzed guar gum mixture (I-PHGG) for the treatment of constipation in females, as well as its influence on the composition of intestinal microbiota and production of short chain fatty acids. METHODS: Our study enrolled 60 constipated female health worker volunteers. Participants reported less than 3 bowel movements per week. Volunteers were randomized to treatment with prebiotic or placebo. Treatment consisted of 3 weeks supplementation with 15 g/d IPHGG (fiber group) or maltodextrin (placebo group). Abdominal discomfort, flatulence, stool consistency, and bowel movements were evaluated by a recorded daily questionnaire and a weekly interview. Changes in fecal bacterial population and short chain fatty acids were assessed by real-time PCR and gas chromatography, respectively. RESULTS: There was an increased frequency of weekly bowel movements and patient satisfaction in both the fiber and placebo groups with no significant differences. Total Clostridium sp significantly decreased in the fiber group (p = 0.046) and increased in the placebo group (p = 0.047). There were no changes in fecal short chain fatty acid profile. CONCLUSIONS: Consumption of I-PHGG produced clinical results comparable to placebo in constipated females, but had additional protective effects on gut microbiota by decreasing the amount of pathological bacteria of the Clostridium genera.

Microbiota benefits after inulin and partially hydrolized guar gumsupplementation - a randomized clinical trial in constipated women / Beneficios en la microbiota intestinal después de la suplementación con inulina y la goma guar parcialmente hidrolizada - un ensayo clínico aleatorizado en mujeres con estreñimiento

Introduction: Prebiotics positively affect gut microbiota composition, thus improving gut function. These properties may be useful for the treatment of constipation. Objectives: This study assessed the tolerance and effectiveness of a prebiotic inulin/partially hydrolyzed guargum mixture (I-PHGG) for the treatment of constipation in females, as well as its influence on the composition of intestinal microbiota and production of short chain fattyacids. Methods: Our study enrolled 60 constipated female health worker volunteers. Participants reported less than3 bowel movements per week. Volunteers were randomized to treatment with prebiotic or placebo. Treatment consisted of 3 weeks supplementation with 15 g/d IPHGG (fiber group) or maltodextrin (placebo group).Abdominal discomfort, flatulence, stool consistency, and bowel movements were evaluated by a recorded daily questionnaire and a weekly interview. Changes in fecal bacterial population and short chain fatty acids were assessed by real-time PCR and gas chromatography, respectively. Results: There was an increased frequency of weekly bowel movements and patient satisfaction in both the fiber and placebo groups with no significant differences. Total Clostridium sp significantly decreased in the fibergroup (p = 0.046) and increased in the placebo group (p =0.047). There were no changes in fecal short chain fatty acid profile. Conclusions: Consumption of I-PHGG produced clinical results comparable to placebo in constipated females, but had additional protective effects on gut microbiota by decreasing the amount of pathological bacteria of the Clostridium genera (AU)

Introducción: Los prebióticos influyen positivamente en la composición de la microbiota intestinal, mejorando así la función intestinal. Estas propiedades pueden ser útiles para el tratamiento del estreñimiento. Objetivos: Este estudio evaluó la tolerancia y la eficacia de una mezcla de prebiótico inulina con la goma guar parcialmente hidrolizada (I-PHGG) para el tratamiento de mujeres con estreñimiento, así como su influencia en la composición de la microbiota intestinal y la producción de ácidos grasos de cadena corta. Métodos: Nuestro estudio contó con la participación de60 mujeres voluntarias con estreñimiento y profesionales de la salud. Las participantes informaron tener menos de tres evacuaciones por semana y fueron asignadas aleatoriamente a tratamiento con prebióticos o placebo. El tratamiento consistió en 3 semanas de suplementación con 15 gd I-PHGG (grupo de fibras) o maltodextrina (grupo placebo). Malestar abdominal, flatulencia, consistencia de las heces, y los movimientos intestinales se evaluaron mediante un cuestionario de registro diario y una entrevista semanal. Cambios en la población de bacterias fecales y los ácidos grasos de cadena corta fueron evaluados por PCR entiempo real y cromatografía de gases, respectivamente. Resultados: Hubo un aumento en la frecuencia de las evacuaciones intestinales por semana y la satisfacción del paciente, tanto en la fibra y el grupo placebo, sin diferencias significativas. El total de Clostridium sp disminuyó significativamente en el grupo de fibras (p = 0,046) y aumentó en el grupo placebo (p = 0,047). No hubo cambios en el perfil fecal de ácidos grasos de cadena corta. Conclusiones: El consumo de I-PHGG ha producido resultados clínicos comparables a placebo en mujeres con estreñimiento, pero ofreció otros efectos protectores sobre la microbiota intestinal al disminuir la cantidad de bacterias patológicas de lo género Clostridium (AU)

Pharmacokinetics of rifampin and clarithromycin in patients treated for Mycobacterium ulcerans infection.

In a randomized controlled trial in Ghana, treatment of Mycobacterium ulcerans infection with streptomycin (SM)-rifampin (RIF) for 8 weeks was compared with treatment with SM-RIF for 4 weeks followed by treatment with RIF-clarithromycin (CLA) for 4 weeks. The extent of the interaction of RIF and CLA combined on the pharmacokinetics of the two compounds is unknown in this population and was therefore studied in a subset of patients. Patients received CLA at a dose of 7.5 mg/kg of body weight once daily, rounded to the nearest 125 mg. RIF was administered at a dose of 10 mg/kg, rounded to the nearest 150 mg. SM was given at a dose of 15 mg/kg once daily as an intramuscular injection. Plasma samples were drawn at steady state and analyzed by liquid chromatography-tandem mass spectroscopy. Pharmacokinetic parameters were calculated with the MW/Pharm (version 3.60) program. Comedication with CLA resulted in a 60% statistically nonsignificant increase in the area under the plasma concentration-time curve (AUC) for RIF of 25.8 mg x h/liter (interquartile ratio [IQR], 21.7 to 31.5 mg x h/liter), whereas the AUC of RIF was 15.2 mg x h/liter (IQR, 15.0 to 17.5 mg x h/liter) in patients comedicated with SM (P = 0.09). The median AUCs of CLA and 14-hydroxyclarithromycin (14OH-CLA) were 2.9 mg x h/liter (IQR, 1.5 to 3.8 mg x h/liter) and 8.0 mg x h/liter (IQR, 6.7 to 8.6 mg x h/liter), respectively. The median concentration of CLA was above the MIC of M. ulcerans, but that of 14OH-CLA was not. In further clinical studies, a dose of CLA of 7.5 mg/kg twice daily should be used (or with an extended-release formulation, 15 mg/kg should be used) to ensure higher levels of exposure to CLA and an increase in the time above the MIC compared to those achieved with the currently used dose of 7.5 mg/kg once daily.

Effect of intrauterine position on sex differences in the gabaergic system and behavior of rats.

In multiparous species such as the rat (in this case the albino Wistar strain), steroid influence during fetal growth is affected by the relative intrauterine position of male and female fetuses and is stronger when the potential effects of contiguity and caudal position are combined. The effect of intrauterine position on gonadal steroid levels in neonatal and adult animals was examined using radioimmunoassay techniques. Since the organizing effect of prenatal steroids may influence the postnatal GABA content, HPLC was used to determine the gabaergic content in several hypothalamic and limbic areas in the adult rat. The effects of intrauterine position on adaptive behavior were examined by recording exploratory behavior (using the corridor and hole board tests) and intraspecific aggression (induced by isolation). Female pups influenced by males during development produced more testosterone. In adult males, those that developed closer to the cervix (and with no influence from other fetuses) produced more testosterone and less estradiol. The same animals also produced more hypothalamic GABA and showed greater exploratory capacity. No significant differences were seen between any experimental groups with respect to aggression. These results show increased variability between males with respect to adult exploratory behavior, and in the neurochemical and endocrine systems involved, due to intrauterine position during development. The effect of this physiological phenomenon on the structure of rodent populations is discussed.

A cólera no Estado do Rio Grande do Norte--Brasil--perfil sorológico e de sensibilidade do Vibrio cholerae a diferentes antimicrobianos / Cholera in Rio Grande do Norte State--Brazil: sorology and sensitivity of Vibrio cholerae to different antimicrobials

PURPOSE: The emergence of multiple resistance to antimicrobials in Vibrio cholerae isolated in the state of Ceará, Brazil, alerted researchers in this area to the sensitivity to antimicrobials of strains isolated in Rio Grande do Norte (RN), Brazil. METHODS: One hundred and four strains of V. cholerae of human origin, isolated by Laboratório Central de Saúde Pública Dr. Almino Fernandes, were serologically typified and evaluated for in vitro sensitivity to eight antibiotics belonging to different groups (polymyxine, tetracycline, chloramphenicol, nitrofurantoin, sulphazotrin, pefloxacine, erythromycine, ampicillin). The strains were collected from patients suspected of contracting choleric diarrhea in the year 1999, in Natal/RN/Brazil. RESULTS: From the sample total, 100 were identified as V. cholerae, serogroup O:1, biotype El Tor, with 99 (95.3%) belonging to serovar Ogawa and only 1 (0.9%) to serovar Inaba. The 4 remaining were characterized as non O:1 V. cholerae, with 3 (2.9%) biochemically identified as Heiberg type I and 1 (0.9%) as type II. All the V. cholerae serogroup O:1 strains were sensitive to tetracycline, chloramphenicol, sulphazotrin, pefloxacine, erythromycine and resistant to polymyxine. In relation to nitrofurantoin, only 1 was sensitive. Only 1 was resistant to ampicillin. The non O:1 V. cholerae strains were resistant to polymyxine. CONCLUSIONS: The results showed sensitivity in 100% of the V. cholerae serogroup O:1 strains to tetracycline, an elective drug in the treatment of cholera, and an absence of multiple resistant strains in our environment. An interesting finding was the frequency of serovar Ogawa in 1999, considering the greater incidence of serovar Inaba in other years of cholera outbreaks in RN.

Pollen and mold exposure impairs the work performance of employees with allergic rhinitis.

BACKGROUND: Although quality of life studies suggest that allergic rhinitis has a substantial impact on work impairment, national survey estimates of the magnitude of this impairment have varied widely. Retrospective recall bias is likely to be a major cause of this variability. OBJECTIVE: This study used a nationally representative daily diary sample to obtain prospective data that improve on previous estimates of the work impairment because of allergic rhinitis. METHODS: The MacArthur Foundation National Survey of Daily Experience is a daily diary survey that included a nationally representative subsample of 739 employed people, each of whom provided daily reports on work performance for 1 randomly assigned week of the calendar year. National Allergy Bureau monitoring station data were merged with the survey data to study the association of time-space variation in pollen/mold exposure with impaired daily work quality and quantity. RESULTS: National Allergy Bureau pollen/mold counts are significantly related to work impairments only among respondents with self-reported allergic rhinitis. The average estimated monthly salary-equivalent work impairment costs associated with pollen/mold exposure for each allergy sufferer is between $109 and $156, with an annualized national projection of between $5.4 billion and $7.7 billion. CONCLUSIONS: The extent to which these costs can be recovered by increasing the proportion of allergy sufferers who are successfully treated remains unknown and can only be evaluated definitively in effectiveness trials.