Phylosymbiosis and metabolomics resolve phenotypically plastic and cryptic sponge species in the genus Agelas across the Caribbean basin

Fundamental to holobiont biology is recognising how variation in microbial composition and function relates to host phenotypic variation. Sponges often exhibit considerable phenotypic plasticity and also harbour dense microbial communities that function to protect and nourish hosts. One of the most prominent sponge genera on Caribbean coral reefs is Agelas. Using a comprehensive set of morphological (growth form, spicule), chemical and molecular data on 13 recognised species of Agelas in the Caribbean basin, we were able to define only five species (=clades) and found that many morphospecies designations were incongruent with phylogenomic and population genetic analyses. Microbial communities were also strongly differentiated between phylogenetic species, showing little evidence of cryptic divergence and relatively low correlation with morphospecies assignment. Metagenomic analyses also showed strong correspondence to phylogenetic species, and to a lesser extent, geographical and morphological characters. Surprisingly, the variation in secondary metabolites produced by sponge holobionts was explained by geography and morphospecies assignment, in addition to phylogenetic species, and covaried significantly with a subset of microbial symbionts. Spicule characteristics were highly plastic, under greater impact from geographical location than phylogeny. Our results suggest that while phenotypic plasticity is rampant in Agelas, morphological differences within phylogenetic species affect functionally important ecological traits, including the composition of the symbiotic microbial communities and metabolomic profiles.

Members of the Candidate Phyla Radiation are functionally differentiated by carbon- and nitrogen-cycling capabilities

BACKGROUND

The Candidate Phyla Radiation (CPR) is a recently described expansion of the tree of life that represents more than 15% of all bacterial diversity and potentially contains over 70 different phyla. Despite this broad phylogenetic variation, these microorganisms appear to feature little functional diversity, with members generally characterized as obligate fermenters. Additionally, much of the data describing CPR phyla has been generated from a limited number of environments, constraining our knowledge of their functional roles and biogeographical distribution. To expand our understanding of subsurface CPR microorganisms, we sampled four separate groundwater wells over 2 years across three Ohio counties.

RESULTS

Samples were analyzed using 16S rRNA gene amplicon and shotgun metagenomic sequencing. Amplicon results indicated that CPR members comprised between 2 and 20% of the microbial communities with relative abundances stable through time in Athens and Greene samples but dynamic in Licking groundwater. Shotgun metagenomic analyses generated 71 putative CPR genomes, representing roughly 32 known phyla and 2 putative new phyla, Candidatus Brownbacteria and Candidatus Hugbacteria. While these genomes largely mirrored metabolic characteristics of known CPR members, some features were previously uncharacterized. For instance, nitrite reductase, encoded by nirK, was found in four of our Parcubacteria genomes and multiple CPR genomes from other studies, indicating a potentially undescribed role for these microorganisms in denitrification. Additionally, glycoside hydrolase (GH) family profiles for our 71 genomes and over 2000 other CPR genomes were analyzed to characterize their carbon-processing potential. Although common trends were present throughout the radiation, differences highlighted potential mechanisms that could allow microorganisms across the CPR to occupy various subsurface niches. For example, members of the Microgenomates superphylum appear to potentially degrade a wider range of carbon substrates than other CPR phyla.

CONCLUSIONS

CPR members are present across a range of environments and often constitute a significant fraction of the microbial population in groundwater systems, particularly. Further sampling of such environments will resolve this portion of the tree of life at finer taxonomic levels, which is essential to solidify functional differences between members that populate this phylogenetically broad region of the tree of life.

Species differences and effects of soft coral extracts from Sinnularia maximus on the expression of cytochrome P4501A and 2N in butterflyfishes (Chaetodon spp.)

Cytochrome P450 (CYP) has been shown to confer resistance in numerous terrestrial insects that consume potentially toxic secondary metabolites in plants, but fewer studies have examined the role of critical biotransformation enzymes in allowing marine organisms to consume chemically defended foods. This study examined the expression of CYP1A and CYP2N mRNAs in several butterflyfish species, which can feed on numerous chemically defended soft and hard corals. In addition, the effect of an extract from a soft coral (Sinnularia maxima) on expression of hepatic CYP1A and CYP2 mRNAs was also examined. Fish were fed extracts on days 1, 3 and 5, and expression was examined on day 5. Phylogenetic analyses of the CYP1A cDNA from 12 species of butterflyfish (DNA, amino acid) indicate well-separated groupings according to their feeding strategies. The non-coralline feeding Chaetodon xanthurus exhibited a 7-fold higher basal expression of CYP2N8 relative to the other species studied. Although induction of CYP2N7 expression was observed in C. punctatofasciatus, CYP1A and CYP2N was largely unaffected or diminished by extract treatment in the other species of butterflyfish. These results indicated groupings of feeding strategy with CYP1A phylogeny in Chaetodon, but generally unaltered expression of CYP1A and CYP2N following dietary treatment with an extract from a chemically defended soft coral suggesting an inconclusive role of these isoforms in the detoxification of chemicals in these extracts.

Aplysina red band syndrome: a new threat to Caribbean sponges

A substantial and increasing number of reports have documented dramatic changes and continuing declines in Caribbean coral reef communities over the past 2 decades. To date, the majority of disease reports have focused on scleractinian corals, whereas sponge diseases have been less frequently documented. In this study, we describe Aplysina red band syndrome (ARBS) affecting Caribbean rope sponges of the genus Aplysina observed on shallow reefs in the Bahamas. Visible signs of disease presence included 1 or more rust-colored leading edges, with or without a trailing area of necrotic tissue, such that the lesion forms a contiguous band around part or all of the sponge branch. Microscopic examination of the leading edge of the disease margin indicated that a cyanobacterium was consistently responsible for the coloration. Although the presence of this distinctive coloration was used to characterize the diseased state, it is not yet known whether this cyanobacterium is directly responsible for disease causation. The prevalence of ARBS declined significantly from July to October 2004 before increasing above July levels in January 2005. Transmission studies in the laboratory demonstrated that contact with the leading edge of an active lesion was sufficient to spread ARBS to a previously healthy sponge, suggesting that the etiologic agent, currently undescribed, is contagious. Studies to elucidate the etiologic agent of ARBS are ongoing. Sponges are an essential component of coral reef communities and emerging sponge diseases clearly have the potential to impact benthic community structure on coral reefs.

Hormone replacement therapy and colorectal adenoma recurrence among women in the Polyp Prevention Trial

BACKGROUND

Epidemiologic studies have suggested that estrogen may protect against the development of colorectal cancers and adenomatous polyps. We conducted a prospective study to evaluate the association between hormone replacement therapy (HRT) and adenoma recurrence among perimenopausal and postmenopausal women participating in the Polyp Prevention Trial, a randomized dietary intervention study of individuals with colorectal adenomas.

METHODS

We used a questionnaire and interviews to collect detailed information, at baseline and at each of four annual study visits, from 620 women regarding hormone use, menopausal status, diet, alcohol consumption, and other risk factors. Adenoma recurrence was ascertained by complete colonoscopy at baseline and after 1 and 4 years. Logistic regression models were used to evaluate the association between hormone use and adenoma recurrence after adjusting for intervention group and for age and body mass index at baseline. All statistical tests were two-sided.

RESULTS

Adenomas recurred in 200 women. There was no overall association between adenoma recurrence and either overall hormone use (odds ratio [OR] = 1.01; 95% confidence interval [CI] = 0.70 to 1.45), combined estrogen and progestin use (OR = 0.94; 95% CI = 0.57 to 1.56), or unopposed estrogen use (OR = 1.04; 95% CI = 0.68 to 1.59). HRT use was associated with a reduction in risk for recurrence of distal adenomas (OR = 0.56; 95% CI = 0.32 to 1.00) and a statistically nonsignificant increase in risk for recurrence of proximal adenomas (OR = 1.39; 95% CI = 0.85 to 2.26). We observed a statistically significant interaction between the HRT-adenoma recurrence association and age (P =.02). HRT was associated with a 40% reduced risk of adenoma recurrence among women older than 62 years (OR = 0.58; 95% CI = 0.35 to 0.97) but with an increased risk among women younger than 62 years (OR = 1.99; 95% CI = 1.11 to 3.55).

CONCLUSIONS

HRT was not associated with a reduced risk for overall adenoma recurrence in this trial cohort, although there was a suggestion of an age interaction. The effect of age on the association needs to be confirmed in other adenoma recurrence trials.

Implementation of a 4-y, high-fiber, high-fruit-and-vegetable, low-fat dietary intervention: results of dietary changes in the Polyp Prevention Trial

BACKGROUND

The Polyp Prevention Trial (PPT) was a multicenter randomized clinical trial designed to determine the effects of a high-fiber (4.30 g/MJ), high-fruit-and-vegetable (0.84 servings/MJ), low-fat (20% of energy from fat) diet on the recurrence of adenomatous polyps in the large bowel.

OBJECTIVE

Our goal was to determine whether the PPT intervention plan could effect change in 3 dietary goals and to examine the intervention's effect on the intake of other food groups and nutrients.

DESIGN

Participants with large-bowel adenomatous polyps diagnosed in the past 6 mo were randomly assigned to either the intervention (n = 1037) or the control (n = 1042) group and remained in the trial for 4 y. Three dietary assessment instruments were used to measure dietary change: food-frequency questionnaires (in 100% of the sample), 4-d food records (in a 20% random cohort), and 24-h dietary recalls (in a 10% random sample).

RESULTS

Intervention participants made and sustained significant changes in all PPT goals as measured by the dietary assessment instruments; the control participants' intakes remained essentially the same throughout the trial. The absolute differences between the intervention and control groups over the 4-y period were 9.7% of energy from fat (95% CI: 9.0%, 10.3%), 1.65 g dietary fiber/MJ (95% CI: 1.53, 1.74), and 0.27 servings of fruit and vegetables/MJ (95% CI: 0.25, 0.29). Intervention participants also reported significant changes in the intake of other nutrients and food groups. The intervention group also had significantly higher serum carotenoid concentrations and lower body weights than did the control group.

CONCLUSION

Motivated, free-living individuals, given appropriate support, can make and sustain major dietary changes over a 4-y period.

The efficacy of functional foot orthoses in the control of pain in ankle joint disintegration in hemophilia

Sixteen subjects with hemophilia A of levels 1-5 stage of joint damage were tested over a 6-week period to evaluate the efficacy of functional foot orthoses. The level of ankle bleeds (hemarthrosis) before and after the intervention with functional foot orthoses was determined by evaluating pain, disability, and activity levels. All subjects reported a significant reduction of ankle bleeds coinciding with the intervention of functional foot orthoses. The use of a foot-pain disability measure clearly showed significant reduction in the level of pain experienced by the subjects and in their overall index score. However, the disability and activity index scores showed no significant improvement after the intervention with orthoses. This finding would support the use of functional foot orthoses to treat patients with hemophilia A, as significant reduction in pain levels appears to greatly improve the lives of the patients.

Competition-Mediated Antibiotic Induction in the Marine Bacterium Streptomyces tenjimariensis

Microbial competition for limiting natural resources within a community is thought to be the selective force that promotes biosynthesis of antimicrobial compounds. The marine bacterium Streptomyces tenjimariensis produces the antibiotics istamycin A and B under select laboratory culture conditions; presumably these compounds serve an ecological role under natural conditions. Here we report results of a novel marine microbial competition experiment that examined the impact of co-culture of marine bacteria on istamycin production by S. tenjimariensis. Twelve of the 53 bacterial species tested (i.e., 22.6%) induced Istamycin production; this antibiotic also inhibited growth of the competitor colonies. These results suggest that marine bacterial metabolites serve an ecological role in countering competitive species.

PCR bias toward the wild-type k-ras and p53 sequences: implications for PCR detection of mutations and cancer diagnosis

PCR-based cancer diagnosis requires detection of rare mutations in k-ras, p53 or other genes. The assumption has been that mutant and wild-type sequences amplify with near equal efficiency, so that they are eventually present in proportions representative of the starting material. Work on factor IX suggests that this assumption is invalid for one case of near-sequence identity. To test the generality of this phenomenon and its relevance to cancer diagnosis, primers distant from point mutations in p53 and k-ras were used to amplify wild-type and mutant sequences from these genes. A substantial bias against PCR amplification of mutants was observed for two regions of the p53 gene and one region of k-ras. For k-ras and p53, bias was observed when the wild-type and mutant sequences were amplified separately or when mixed in equal proportions before PCR. Bias was present with proofreading and non-proofreading polymerases. Mutant and wild-type segments of the factor V, cystic fibrosis transmembrane conductance regulator and prothrombin genes were amplified and did not exhibit PCR bias. Therefore, the assumption of equal PCR efficiency for point mutant and wild-type sequences is invalid in several systems. Quantitative or diagnostic PCR will require validation for each locus, and enrichment strategies may be needed to optimize detection of mutants.

Performance of a new blood pressure monitor in children and young adults: the difficulties in clinical validation

The aim of this study was to assess the performance of a new ambulatory blood pressure monitor (Dynapulse 5000A) in children and young adults. The reference methods, i.e. the mercury-Doppler (Hg-D) method of blood-pressure measurement (recommended for less than 5-year-old children by the British Hypertension Society criteria) and the mercury-auscultation (Hg-A) technique (recommended for 5 years and above) were initially compared utilizing 132 concomitant systolic blood pressure (SBP) readings taken among 44 subjects (3 in each) aged 2-30 years. Hg-D over-read SBP above that of the conventional Hg-A by a mean of 5.25 mmHg (95% confidence interval (CI) 4.11, 6.4). This difference in measurement between the two techniques was also significantly (p = 0.01) related to age. [Difference in mmHg = 7.83 (95% CI 5.53, 10.12) -0.30 (95% CI -0.54, -0.07) age in years.] The Dynapulse 5000A was therefore validated only against Hg-D throughout the age range and was undertaken utilizing 468 concomitant resting SBP measurements taken among 59 subjects (supine or sitting) using a 'T' system. The Dynapulse was found to give higher SBP readings (average 13.5 mmHg) than Hg-D sphygmomanometry. Although the differences were not dependent on the age of the child, the pulse rate or the body mass index, there was a significant drift in the differences with time (-0.05 mmHg/day). Repeatability of each of the measurement methods calculated utilizing two or three consecutive recordings taken at 1-min intervals showed that variability between repeated measurements made with the Dynapulse (14.8%) was greater than for Hg-D. Repeatability coefficient of the Hg-D (11.2%) was also less than ideal for a reference method. We conclude that Dynapulse 5000A over-reads SBP above that detected by Hg-D, but cannot be fairly graded by British Hypertension Society criteria due to the inconsistency and poor repeatability of the recommended reference methods.

Indexes of food and nutrient intakes as predictors of serum concentrations of nutrients: the problem of inadequate discriminant validity. The Polyp Prevention Trial Study Group

Nutrient indexes derived from food-frequency questionnaires have generally been regarded as acceptably valid for epidemiologic purposes. Evaluations of these indexes, however, have considered only their convergent validity. We suggest that discriminant validity, or the ability to distinguish among exposures to different nutrients, is also important. Using baseline data from a large clinical trial, we tested the discriminant validity of indexes of intake of vitamin E, alpha-carotene, and beta-carotene. Our results suggest that the vitamin E index possesses neither convergent not discriminant validity, the alpha-carotene index adequate convergent and discriminant validity, and the beta-carotene index adequate convergent but no discriminant validity.

Four Corners Research Consortium for Native Americans and cancer research

Cancer morbidity and mortality in Native Americans in the Southwestern four-corners region of the United States (Arizona, Colorado, New Mexico, and Utah) is of critical concern to public health workers, health care providers, cancer researchers, and Native American communities of the region. As a follow-up to the national conference in Seattle, Washington, representatives from the Arizona, Colorado, New Mexico, and Utah Cancer Centers, the AMC Cancer Research Center, and the Indian Health Service participated in a regional conference on September 26, 1995. The primary reason for the "Four Corners Consortium" meeting was to assess cancer research activities in each state and to determine how Native American cancer research could be organized in the four-state region. One interest of the group was to determine strategies to explore why some cancers are more or less prevalent among Southwest Native American populations and to evaluate how the group might jointly establish research that would address the cancer needs of Southwestern tribes.

The polyp prevention trial II: dietary intervention program and participant baseline dietary characteristics

The Polyp Prevention Trial (PPT) is a multicenter randomized controlled trial to evaluate whether a low-fat, high-dietary fiber, high-fruit and -vegetable eating pattern will reduce the recurrence of adenomatous polyps of the large bowel. Men and women who had one or more adenomas removed recently were randomized into either the intervention (n = 1037) or control (n = 1042) arms. Food frequency questionnaire data indicate that PPT participants at the beginning of the trial consumed 36.8% of total energy from fat, 9.7 g of dietary fiber/1000 kcal, and 3.8 daily servings of fruits and vegetables. Baseline dietary characteristics, including intake of fat, fiber, and fruits and vegetables, as well as other macro- and micronutrients, were similar in the two study groups. The intervention participants receive extensive dietary and behavioral counseling to achieve the PPT dietary goals of 20% of total energy from fat, 18 g/1000 kcal of dietary fiber, and 5-8 daily servings (depending on total caloric intake) of fruits and vegetables. Control participants do not receive such counseling and are expected to continue their usual intake. Dietary intake in both groups is mentioned annually using a 4-day food record (also completed at 6 months by intervention participants only) and a food frequency questionnaire, with a 10% random sample of participants completing an annual unscheduled 24-h telephone recall. Blood specimens are drawn and analyzed annually for lipids and carotenoids. This article provides details on the rationale and design of the PPT dietary intervention program and describes the participant baseline dietary intake data characteristics.

Identification of the major brown shrimp (Penaeus aztecus) allergen as the muscle protein tropomyosin

Shrimp, a major seafood allergen, was investigated as a model food allergen. Extracts from both shrimp (Penaeus aztecus) meat and cooking fluid contain a substantial and similar amount of allergenic activity. A 36-kD allergen, demonstrated in both extracts by SDS-PAGE/Western blot analysis, reacted with 28/34 (82%) sera from shrimp-sensitive, skin test and RAST-positive, individuals. This allergen, named Pen a I, was isolated by SDS-PAGE; its amino acid composition was rich in aspartic and glutamic acids. A 21-residue peptide, obtained from endoproteinase Lys-C digested Pen a I by high-performance liquid chromatography, demonstrated significant homology (60-87%) with the muscle protein tropomyosin from various species and origins. The greatest homology (87%) was noted with tropomyosin of the fruit fly (Drosophila melanogaster) reflecting the phylogenic relationship between these two arthropods. These studies demonstrate that tropomyosin is the major shrimp allergen. Although the amino acid sequence of this shrimp muscle protein shares considerable homology with tropomyosins of other species including man, significant differences remain in allergenic activity.

The CARDIA dietary history: development, implementation, and evaluation

To meet the objectives for dietary assessment in the Coronary Artery Risk Development in Young Adults (CARDIA) prospective study, we developed a dietary history to provide accurate and reliable quantitative data on habitual individual nutrient intakes at baseline. The CARDIA dietary history was an interviewer-administered method that included a short questionnaire regarding general dietary practices followed by a comprehensive food frequency questionnaire about typical intake of foods using the previous month as a reference for recall. For each broad category of foods, participants were questioned in detail about specific foods only if they indicated that they consumed foods from that category. Follow-up questions for selected foods concerned serving size, frequency of consumption, and common additions to these foods. Provision was made for reporting foods not found in the food frequency list. The interview took approximately 45 minutes. Cue cards prompted responses and plastic food models assisted in estimating usual amounts consumed. A precoded format standardized coding for reported items and established the detail needed for recall during the interview. Baseline nutrient analyses from the CARDIA dietary history provided estimates that agreed reasonably well with expected caloric intake for body mass index according to the age- and sex-specific Recommended Dietary Allowances, but were higher than those reported from 24-hour recalls for comparable age, sex, and race groups in the second National Health and Nutrition Examination Survey. The CARDIA dietary history is a comprehensive assessment tool that can provide a dietitian with detailed information regarding habitual eating patterns and nutrient intakes among adults.

Postnatal development of neuropeptide Y-like immunoreactivity in area 17 of normal and visually deprived rhesus monkeys

Immunocytochemical methods were used to examine neuropeptide Y (NPY) immunoreactive neurons and fibers in area 17 of rhesus monkeys during the first year of life. NPY-immunoreactive (+) neurons are nonpyramidal cells which are either multipolar, bipolar, or bitufted in shape. They occur most frequently in layer 6 and the subjacent white matter, are sparser in the supragranular layers, and absent from layer 4C. Labeled somata in the supragranular layers are smaller compared to those in layer 6 and the white matter. A typical axon originates from the NPY+ soma or from a primary dendrite and frequently is varicose. Distribution and morphologies of NPY+ neurons in area 17 of infants are similar to those of adult monkeys. Thus, it seems that NPY+ neurons in rhesus monkeys are mature from birth. NPY+ fibers occur in area 17 from birth; however, they differ in density and distribution from those of older infant and adult monkeys. At birth, a prominent fiber plexus is found in the deepest part of layer 1, and another in the white matter. Immunoreactive processes are sparse in the remaining cortical gray, except for some vertical fibers extending from pia to white matter. By 4 months of age, labeled fibers form a coarse network in layers 2, 3, 5, and 6. In addition, a distinct plexus extends through layers 4B, 4A, and the lowest aspect of layer 3. Also, a thin immunoreactive fiber band is found at the bottom of layer 4C. In the remainder of layer 4C, NPY+ fibers are scant. The supragranular layers also exhibit a unique immunoreactive "snarl" of fibers. Increases in density of NPY+ processes in the older infants are gradual so that between 7 and 13 months of age, NPY+ fibers appear to have achieved adultlike densities. These observations indicate that NPY+ fibers in area 17 of newborn rhesus monkeys undergo postnatal maturation which reaches a plateau around 4 months of age. After monocular visual deprivation from birth to 4 months of age, either by eyelid suture or by occlusion with an opaque contact lens, density and distribution of NPY+ neurons and fibers, including snarls, appear similar to those of age-matched undeprived infants. Thus, disruption of the normal binocular input does not seem to arrest the maturation of the NPY system in area 17 of rhesus monkeys during a sensitive period of early postnatal development.

The occupational risks of alcoholism

The occupations of 6,596 psychiatric admissions with alcoholism were analyzed and their admission rates compared with occupational death rates due to cirrhosis of the liver. Two thirds of occupations with high admission rates had correspondingly high cirrhosis death rates but a dozen occupations had low admission rates and high liver cirrhosis death rates, suggesting a degree of heavy drinking which is not treated. Low-risk occupations are identified and their characteristics discussed.

Local differences in the amount of early cell death in neocortex predict adult local specializations

The amount of early cell loss in five neocortical areas was inversely related to adult numbers of neurons in those areas. Differential cell death predicted particularly the thickness of the upper cortical laminae; it was not related to neuron numbers in the lower laminae. Cell loss thus determines some features of local neocortical differentiation.

Clinical application of human-placental-lactogen values in late pregnancy

Human-placental-lactogen (H.P.L.) levels were measured in the blood of 1000 women in the third trimester of pregnancy to see how measurement of H.P.L. could help in the management of an obstetric population in Britain. It was found that in the 93% of the population with a mean H.P.L. level of 4.3 mg/l or above, only 1.1% would have a poor pregnancy and 4.8% a compromised pregnancy. Of the 7% with levels below 4.3 mg/l, 57% woul have a normal outcome and 43% a poor or indifferent outcome. The false-positive rate was considerable, but the results of the study indicate nevertheless that H.P.L. levels are useful in predicting the outcome of pregnancy and that their measurement should be included as part of routine screening in the third trimester.

Twice weekly prophylactic therapy in haemophilia A

Factor VIII-containing materials were administered to four severely affected haemophiliacs twice weekly in doses calculated to raise the factor VIII level to either 15% or 30% of average normal. The pooled results from those patients with statistically similar baseline bleeding frequencies showed a significant reduction in bleeding frequency on both doses in the first 48 hours. The 30% dose produced a more significant reduction than the 15% dose in the first 24 hours, but there was no significant difference between the two doses in the second 24 hours. It appears that to reduce the bleeding frequency of severely affected haemophiliacs by 60% would require a two-and-a-half-fold increase in therapeutic materials. A 90% reduction would need nine times the amount of material currently in use.

Prophylaxis in haemophilia: a double-blind controlled trial

A double-blind controlled trial of prophylactic factor VIII therapy has been carried out on nine severe haemophiliacs at the Lord Mayor Treloar College. Infusions were given once weekly and calculated to give a post-infusion plasma concentration of at least 0.25 I.U./ml of factor VIII. This regime reduced the overall bleeding frequency by 15%. The bleeding frequency in the first 3 days post-infusion was reduced by 66%. A moderate overall reduction in morbidity was also achieved. It is calculated that to reduce the incidence of bleeding in severe haemophiliacs by 15% would require a 73% increased usage of therapeutic materials. More than twice this amount of material is likely to be needed to reduce the bleeding frequency of the same group by 66%.