Improving our chemistry: challenges and opportunities in the interdisciplinary study of floral volatiles.

The field of chemical ecology was established, in large part, through collaborative studies between biologists and chemists with common interests in the mechanisms that mediate chemical communication in ecological and evolutionary contexts. Pollination is one highly diverse and important category of such interactions, and there is growing evidence that floral volatiles play important roles in mediating pollinator behaviour and its consequences for plant reproductive ecology and evolution. Here we outline next-generation questions emerging in the study of plants and pollinators, and discuss the potential for strengthening collaboration between biologists and chemists in answering such questions.

Selection of trait combinations through bee and fly visitation to flowers of Polemonium foliosissimum.

Pollinators are known to exert natural selection on floral traits, but the extent to which combinations of floral traits are subject to correlational selection (nonadditive effects of two traits on fitness) is not well understood. Over two years, we used phenotypic manipulations of plant traits to test for effects of flower colour, flower shape and their interaction on rates of pollinator visitation to Polemonium foliosissimum. We also tested for correlational selection based on weighting visitation by the amount of conspecific pollen delivered per visit by each category of insect visitor. Although bumblebees were the presumed pollinators, solitary bees and flies contributed substantially (42%) to pollination. In manipulations of one trait at a time, insects visited flowers presenting the natural colour and shape over flowers manipulated to present artificial mutants with either paler colour or a more open or more tubular flower. When both colour and shape were manipulated in combination, selection on both traits arose, with bumblebees responding mainly to colour and flies responding mainly to shape. Despite selection on both floral traits, in a year with many bumblebees, we saw no evidence for correlational selection of these traits. In a year when flies predominated, fly visitation showed a pattern of correlational selection, but not favouring the natural phenotype, and correlational selection was still not detected for expected pollen receipt. These results show that flower colour and shape are subject to pollinator-mediated selection and that correlational selection can be generated based on pollinator visitation alone, but provide no evidence for correlational selection specifically for the current phenotype.

Where have all the blue flowers gone: pollinator responses and selection on flower colour in New Zealand Wahlenbergia albomarginata.

Although pollinators are thought to select on flower colour, few studies have experimentally decoupled effects of colour from correlated traits on pollinator visitation and pollen transfer. We combined selection analysis and phenotypic manipulations to measure the effect of petal colour on visitation and pollen export at two spatial scales in Wahlenbergia albomarginata. This species is representative of many New Zealand alpine herbs that have secondarily evolved white or pale flowers. The major pollinators, solitary bees, exerted phenotypic selection on flower size but not colour, quantified by bee vision. When presented with manipulated flowers, bees visited flowers painted blue to resemble a congener over white flowers in large, but not small, experimental arrays. Pollen export was higher for blue flowers in large arrays. Pollinator preference does not explain the pale colouration of W. albomarginata, as commonly hypothesized. Absence of bright blue could be driven instead by indirect selection of correlated characters.

A computer-assisted depression intervention in primary care.

BACKGROUND: The clinical benefit for depression of an interactive computer-assisted cognitive-behavioral program on CD-ROM, the Wellness Workshop (WW), was evaluated in a randomized controlled trial. METHOD: A total of 191 individuals referred by primary-care physicians were randomly assigned to a control group, where physician-directed treatment as usual (TAU) was provided, or to a treatment group, where TAU was supplemented with the WW CD-ROM, delivered by mail (WW+TAU). Data were collected at baseline, at 6 weeks' post-intervention, and at a 6-month follow-up assessment. Participants were given a strong incentive by a reimbursement of $75 for completion of each assessment. Measures included symptom ratings obtained via structured clinical diagnostic interviews, as well as a battery of self-report questionnaires on symptoms specifically targeted by the intervention. RESULTS: Analysis of results demonstrated evidence for skill acquisition for improving dysfunctional thinking and reducing anxiety. Among those who met diagnostic criteria for depression, WW+TAU participants were three times more likely to remit at 6 weeks' post-test than TAU participants. CONCLUSIONS: The evidence supports the conclusion that the WW intervention added benefit to traditional care for depression. No placebo comparison group was included and the WW+TAU participants received slightly more attention (a supportive telephone contact, ≤ 5 min from a psychologist 2 weeks after receiving the program). Overall, the findings add support to the accumulating evidence for the potential clinical benefit of computer-assisted behavioral health interventions.

Genetic and morphological patterns show variation in frequency of hybrids between Ipomopsis (Polemoniaceae) zones of sympatry.

Variation in rates of hybridization among zones of sympatry between a pair of species provides a useful window into the effect of local conditions on the evolution of reproductive isolation. We employed floral morphological traits and neutral genetic markers to quantify the frequency of individuals intermediate to the two parental species in two zones of sympatry between Ipomopsis aggregata and I. tenuituba, using clustering methods that make no a priori assumptions about population structure. The sites differed not only in the frequency of intermediate individuals, but also in climate, pollinator abundance and behavior and spatial structure of plant populations. Both floral traits, which are likely to be under natural selection and molecular markers, which are quasi-neutral, indicated more population structure at one site than the other, the pattern being more pronounced for floral morphology. One likely explanation for this difference between sites is that local ecological conditions, particularly pollinator choice of flowers, have promoted different rates of hybridization between these species. Hence, the evolution of reproductive isolation might depend in part on local conditions, and thus differ among populations of the same pair of species.

Sexual dimorphism and the genetic potential for evolution of sex allocation in the gynodioecious plant, Schiedea salicaria.

Sex allocation theory addresses how separate sexes can evolve from hermaphroditism but little is known about the genetic potential for shifts in sex allocation in flowering plants. We tested assumptions of this theory using the common currency of biomass and measurements of narrow-sense heritabilities and genetic correlations in Schiedea salicaria, a gynodioecious species under selection for greater differentiation of the sexes. Female (carpel) biomass showed heritable variation in both sexes. Male (stamen) biomass in hermaphrodites also had significant heritability, suggesting the potential for further evolution of dioecy. Significant positive genetic correlations between females and hermaphrodites in carpel mass may slow differentiation between the sexes. Within hermaphrodites, there were no negative genetic correlations between male and female biomass as assumed by models for the evolution of dioecy, suggesting that S. salicaria is capable of further changes in biomass allocation to male and female functions and evolution toward dioecy.

Significance of distal polyps detected with flexible sigmoidoscopy in asymptomatic patients.

BACKGROUND: Colorectal cancer is a frequent cause of death from cancer. To reduce the mortality associated with this disease, regular flexible sigmoidoscopy is recommended. However, the significance of diminutive polyps (adenomatous or hyperplastic) detected during flexible sigmoidoscopy remains controversial, as does the appropriate endoscope length (35 vs 60 cm) for colorectal cancer screening. METHODS: One hundred one consecutive patients with no history of colonic disease, gastrointestinal tract symptoms, or positive results of fecal occult blood testing underwent flexible sigmoidoscopy as part of a colorectal cancer screening program. All patients with distal polyps detected during flexible sigmoidoscopy underwent colonoscopy. RESULTS: More than 25% of these asymptomatic, predominantly male subjects had colonic neoplasms or polyps detected. Fifty percent more lesions could be detected with a 60-cm sigmoidoscope than with a 35-cm sigmoidoscope, and detection of any distal polyp, whether adenomatous or hyperplastic, was associated with at least one proximal colon adenoma in 20% of patients. "Extended flexible sigmoidoscopy" for colorectal cancer screening was well tolerated by patients, as evidenced by insertion to the hepatic flexure in 25% of patients, and provided significantly more information than could be obtained with a 35-cm sigmoidoscope. CONCLUSIONS: Colorectal cancer screening should be performed with a 60-cm flexible sigmoidoscope, and distal colonic polyps or neoplasms will be detected in 25% of asymptomatic patients.

Lansoprazole compared with ranitidine for the treatment of nonerosive gastroesophageal reflux disease.

BACKGROUND: Traditionally, proton pump inhibitors are used primarily for patients with esophagitis. However, patients with nonerosive reflux disease may also benefit from these powerful medications. OBJECTIVE: To compare the safety and symptom relief efficacy of lansoprazole with ranitidine therapy and with placebo. METHODS: In 2 randomized, double-blind, multicenter trials of 901 patients with symptomatic reflux disease, which was confirmed by endoscopy to be nonerosive, received lansoprazole, 15 or 30 mg once daily; ranitidine, 150 mg twice daily; or placebo for 8 weeks. RESULTS: Analysis of daily diary data during the first 4 weeks and for the entire 8 weeks of treatment revealed that patients who were treated with either dosage of lansoprazole reported significantly (P<.05) lower percentages of days and nights with heartburn, less pain severity of both day and night heartburn, fewer days of antacid use, and smaller amounts of antacid use compared with patients who were treated with ranitidine or placebo. The incidence of possible or probable treatment-related adverse reactions was comparable among the treatment groups; abdominal pain and diarrhea were the most commonly reported adverse events. No statistically significant differences were noted between treatment groups in laboratory analyses. CONCLUSION: Lansoprazole therapy is more effective than standard dosages of ranitidine or placebo in relieving symptoms in patients with endoscopically confirmed non-erosive reflux esophagitis.

Superiority of lansoprazole vs ranitidine in healing nonsteroidal anti-inflammatory drug-associated gastric ulcers: results of a double-blind, randomized, multicenter study. NSAID-Associated Gastric Ulcer Study Group.

BACKGROUND: The usefulness of nonsteroidal anti-inflammatory drugs (NSAIDs) is limited by adverse gastrointestinal tract events. OBJECTIVE: To identify the optimal antisecretory therapy for healing of gastric ulcer in patients using NSAIDs and the impact of concurrent Helicobacter pylori infection on ulcer healing. DESIGN: Prospective, double-blind, multicenter, parallel-group study. SETTING: Gastroenterology practices in ambulatory and referral center settings. PATIENTS: Three hundred fifty-three patients with an active, nonmalignant gastric ulcer at least 5 mm in diameter confirmed by endoscopy and biopsy and who continued to receive stable doses of NSAIDs. INTERVENTION: Patients were randomized to receive ranitidine hydrochloride, 150 mg twice daily, or lansoprazole, 15 mg or 30 mg once daily, for 8 weeks. MEASUREMENTS: Healing was assessed by endoscopy at 4 and 8 weeks in an intent-to-treat population. Helicobacter pylori status was assessed by histological examination. RESULTS: After 8 weeks of treatment, healing was observed in 61 (53%) of 115, 81 (69%) of 118, and 85 (73%) of 117 patients receiving ranitidine lansoprazole, 15 mg, and lansoprazole, 30 mg, respectively (P<.05 for ranitidine vs both lansoprazole doses; 95% confidence interval, 3.2-28.0 for ranitidine vs lansoprazole, 15 mg, and 7.4-31.8 for ranitidine vs lansoprazole, 30 mg). The gastric ulcer healing rates were similar between H pylori-infected and -noninfected patients, with a statistically significant increase with the use of lansoprazole vs ranitidine. CONCLUSIONS: In patients who require continuous treatment with NSAIDs, lansoprazole is superior to ranitidine for healing of NSAID-associated gastric ulcers. Healing is not delayed by the presence of H pylori infection.

Psychosocial predictors of self-care behaviors (compliance) and glycemic control in non-insulin-dependent diabetes mellitus.

This study assessed potential psychosocial correlates of self-care behaviors (compliance) and of glycemic control in a community sample of 184 people diagnosed as having non-insulin-dependent (type II) diabetes mellitus. Four different diabetes self-care behaviors were studied (medication taking, glucose testing, diet, and exercise), and glycemic control was assessed by glycosylated hemoglobin analyses. Multiple measures were collected within each of several categories of psychosocial variables including knowledge, stress, depression, anxiety, diabetes-specific health beliefs, and social support. Findings indicate that approximately 25% of the variance in self-care behaviors can be explained by psychosocial and demographic variables. In contrast, psychosocial variables were not significant predictors of level of glycemic control. The diabetes-specific psychosocial measures of health beliefs and social support were the most consistent and strongest predictors of self-care behavior across the different regimen areas studied. Possible reasons for these findings, limitations of the study, and directions for future research are discussed.

Maximizing foot salvage by a combined approach to foot ischemia and neuropathic ulceration in patients with diabetes. A 5-year experience.

OBJECTIVE: The combination of peripheral neuropathy and arterial insufficiency in patients with diabetes frequently results in chronic non-healing foot ulcers. These patients often have a protracted course that commonly ends in limb amputation. RESEARCH DESIGN AND METHODS: Since 1987, 39 diabetic patients presented with 42 neuropathic ulcerations beneath the lesser metatarsal heads, complicated by severe arterial insufficiency. A variety of vascular reconstructions were performed to improve circulation to the foot. After successful vascular reconstruction, 14 patients with deep ulcers underwent resection of the involved bone or joint through a plantar elliptical incision with excision of the ulcer and primary closure (33%). Five patients required a simultaneous panmetatarsal head resection (12%). For fifteen superficial ulcers, metatarsal osteotomy through a dorsal approach was performed (36%). Eight patients underwent a fifth metatarsal head resection through a dorsal approach (19%). RESULTS: In follow-up of 2-64 months (mean 21.2 months), 35 extremities with patent bypass grafts achieved and maintained primary healing of their local foot procedure (83%). Two feet required subsequent revision but ultimately healed (5%). Three feet (7%) developed a new plantar ulceration adjacent to the original one. In two extremities, the foot remained healed in spite of thrombosis of their grafts (5%). One patient with a thrombosed graft required a below-knee amputation. One patient died before the foot healed with a patent bypass graft. Overall, 40 of 42 extremities (95%) ultimately healed over the course of the follow-up period. CONCLUSIONS: We conclude that complex neuropathic ulcers in diabetic patients can be successfully treated by an aggressive surgical approach that removes infected bone and ulcers and corrects underlying structural abnormalities provided arterial insufficiency is corrected first.

Replication of "Prediction of antidepressant response to lithium": problems in generalizing to a clinical setting.

In another study, a simple procedure accurately predicting antidepressant response to lithium was developed in an experimental research setting. The present study failed to replicate these predictors in a clinical setting. The authors suggest using caution in applying these predictors.

Brief group psychotherapy with chronic hemodialysis patients.

The authors selected 11 chronic hemodialysis patients for a brief group psychotherapy program, the primary objective of which was to produce congnitive and affective changes pertaining to the illness. Each of the 10 therapy sessions lasted 1/2 hours and was conducted while the patients were actually on dialysis. Three therapists rated outcome as "good," "fair," or "poor" on 10 objective criteria, and subjective impressions of the group experience were obtained from each patient. The study demonstrated the benefical effects of group therapy, although there was no statistically significant difference between patients in the three outcome categories.

Genotype-by-environment interaction and the fitness of plant hybrids in the wild.

Natural hybrid zones between related species illustrate processes that contribute to genetic differentiation and species formation. A common viewpoint is that hybrids are essentially unfit, but they exist in a stable tension zone where selection against them is balanced by gene flow between the parent species. An alternative idea is that selection depends on the environment, for example, by favoring opposite traits in the two parental habitats or favoring hybrids within a bounded region. To determine whether selection of hybrids is environment dependent, we crossed plants of naturally hybridizing Ipomopsis aggregata and I. tenuituba in the Colorado Rocky Mountains and reciprocally planted the seed offspring into a suite of natural environments across the hybrid zone. All types of crosses produced similar numbers and weights of seeds. However, survival of the offspring after 5 years differed markedly among cross types. On average, the F1 hybrids had survival and growth rates as high as the average for their parents. But hybrid survival depended strongly on the direction of a cross, that is, on which species served as the maternal parent. This fitness difference between reciprocal hybrids appeared only in the parental environments, suggesting cytonuclear gene interactions that are environment specific. These results indicate that complex genotype-by-environment interactions can contribute to the evolutionary outcome of hybridization.

Effect of prolonged supplementation with daily supplements of selenomethionine and sodium selenite on glutathione peroxidase activity in blood of New Zealand residents.

Glutathione peroxidase (EC 1.11.1.9, GSH-Px) activities and selenium (Se) concentrations in blood of 12 New Zealand residents were followed during prolonged supplementation with physiological doses (100 microgram Se) of sodium selenite (selenite-Se) or selenomethionine (Semet-Se). GSH-Px activities increased in all subjects but at 17 wk the mean increase was not significantly greater for Semet-Se (6.2 +/- SD 3.2 units/g Hb) than for selenite-Se (3.7 +/- 1.8 units/g Hb). After dosing ceased, GSH-Px activities for most subjects returned to predosing values in 17 to 40 wk, but in some subjects activities remained high. Increases in Se concentrations in whole blood, erythrocytes, and plasma were greater after Semet-Se than after selenite-se. Se concentrations tended to plateau after selenite-Se while after Semet-Se they continued to rise as long as dosing continued. Enzyme activity of one of four subjects supplemented daily with 500 microgram selenite-Se was unchanged, despite a great increase in plasma Se. Blood Se and GSH-Px of 23 New Zealand residents who ingest regular large doses (0.5 to 3 mg Se) mainly of selenite-Se showed that those who dosed weekly had greater values than the less frequent dosers. Three subjects showed extremely high values. It is suggested that each individual might have an optimal level of GSH-Px activity, so that the level reached is a balance between Se intake and other factors, including possible stressor effect of selenite.

Cerebrospinal fluid ferritin levels in screening for meningism.

To evaluate the potential diagnostic value of the ferritin concentration in cerebrospinal fluid (CSF), measurements were performed with an immunoradiometric assay in 23 control patients and in 65 patients with various neurologic disorders. The geometric mean ferritin level of 3.5 micrograms/L in controls was approximately 10% of the level in normal serum with an upper cutoff level of 10 micrograms/L. Only modest elevations in CSF ferritin concentration were observed in patients with viral meningitis and in those with various non-infectious neurologic disorders. On the other hand, marked elevations ranging between 27 and 322 micrograms/L (geometric mean, 90 micrograms/L) were observed in patients with bacterial or fungal meningitis. Results of the study indicate that CSF ferritin levels are a valuable adjunct in the early evaluation of patients presenting with meningism.

Plasma carotenoids as biomarkers of vegetable and fruit intake.

Higher intakes of vegetables and fruits are associated with a lower risk of certain human cancers. A biomarker of vegetable and fruit intake would be a valuable research tool. A cross-sectional study assessed the association between plasma carotenoid concentrations and intakes of vegetables and fruits. Plasma carotenoids (alpha-carotene, beta-carotene, lutein, beta-cryptoxanthin, and lycopene) were measured in 50 male and 49 female participants, aged 18-37 years, with a wide range of habitual vegetable and fruit intakes. Dietary intakes were assessed via a food frequency questionnaire. Intake of vegetables and fruits and high carotenoid foods were measured. The sum of the plasma carotenoids (excluding lycopene) was highly correlated with intake of total vegetables and fruits (r = 0.59). Of the individual plasma carotenoids, plasma alpha-carotene had the highest correlation with intakes of both total vegetables (r = 0.50) and total fruits (r = 0.58). Intakes of foods with high carotenoid contents were correlated with their corresponding plasma concentrations as follows: high beta-carotene foods (r = 0.41); high lutein foods (r = 0.46); and high lycopene foods (r = 0.11). Multiple regression analyses showed that intake of total vegetables and fruits was the most significant determinant of each plasma carotenoid except lycopene. The utility of combining the plasma carotenoids as biomarkers of vegetable and fruit intake was assessed by a stepwise regression of total vegetable and fruit intake on plasma carotenoids. Significant determinants of intake of total vegetables and fruits were alpha-carotene, beta-cryptoxanthin, lutein, and energy intake (R2 = 0.53).(ABSTRACT TRUNCATED AT 250 WORDS)

Dietary modulation of serum platelet-derived growth factor-AB levels.

Epidemiological studies have demonstrated that diets high in vegetables and fruit are associated with a decreased risk of cancer and, possibly cardiovascular disease. Certain constituents of vegetables and fruit inhibit the in vitro activity of platelet-derived growth factor (PDGF), a potent mitogen implicated in both cancer and cardiovascular disease. Few studies have measured PDGF in relationship to diet in vivo. Specifically, there are no data regarding the changes in PDGF levels of mitogenic activity after a dietary intervention. In this study, 19 young, healthy individuals consumed four (9-day) experimental diets in random order: (a) control diet alone; (b) control diet plus carotenoid-rich vegetables; (c) control diet plus cruciferous vegetables; and (d) control diet plus soy foods. Compared to the control diet, there was a significant elevation in PDGF-AB serum levels when the individuals were consuming the soy diet (P = 0.016). Increased PDGF-AB levels were also noted for the carotenoid diet. There was no change from baseline levels when individuals were consuming the cruciferous diet. Overall, mitogenic activity did not change on any of the experimental diets. This study suggests that high soy and carotenoid diets increase serum levels of PDGF-AB. This may represent an additional mechanism by which diet influences individual risk of cancer; further investigation into the role of diet and growth factors is warranted.

Plasma carotenoids as biomarkers of vegetable intake: the University of Minnesota Cancer Prevention Research Unit Feeding Studies.

High vegetable intake has been associated with a decreased risk for various human cancers in epidemiological studies. Carotenoids are plant compounds that may both possess chemopreventive activity and be useful biomarkers of vegetable and fruit intake. Nineteen men and women were randomized into a controlled cross-over feeding study to measure the effect of vegetable intake on plasma carotenoid concentrations. Participants consumed each of 4 experimental diets for 9 days. The control diet consisted of commonly consumed foods and was essentially carotenoid free. High vegetable diets (carotenoid, cruciferous, and soy) consisted of the control diet plus carrots and spinach (carotenoid), broccoli and cauliflower (cruciferous), and tofu and FriChik (soy). Plasma carotenoid concentrations were highest on the carotenoid and cruciferous diets. When compared to the control, mean plasma alpha-carotene, beta-carotene, and lutein concentrations were 5.2, 3.3 and 2.2 times higher on the carotenoid diet, respectively (P < 0.001). Mean plasma lutein concentrations were 2.1 times higher on the cruciferous versus the control diet (P < 0.001). There were no differences between diets in plasma beta-cryptoxanthin and lycopene concentrations. These data indicate that plasma alpha-carotene, beta-carotene, and lutein may be useful biomarkers of carotenoid-rich food intake and that lutein may act as an intake biomarker of commonly consumed vegetables in the Cruciferae family. These findings should prove useful in undertaking dietary intervention trials because they suggest the feasibility of monitoring intake of some plant foods and of distinguishing among plant food groups.

N-acetyltransferase 1 genetic polymorphism, cigarette smoking, well-done meat intake, and breast cancer risk.

N-Acetyltransferase 1 (NAT1), encoded by the polymorphic NAT1 gene, has been shown to be one of the major enzymes in human breast tissue that activates aromatic and heterocyclic amines. Humans are mainly exposed to these carcinogens through cigarette smoking and consumption of well-done meat. To test the hypothesis that variations in the NAT1 gene are related to breast cancer risk, particularly among women who smoke or consume high levels of well-done meat, a nested case-control study was conducted in a prospective cohort study of 41,837 postmenopausal Iowa women. Information on cigarette smoking and other breast cancer risk factors was obtained at the baseline survey conducted in 1986. DNA samples and information on the consumption of well-done meat were obtained, in the case-control study, from breast cancer cases diagnosed from 1992 to 1994 and a random sample of cancer-free cohort members. Genomic DNA samples obtained from 154 cases and 330 controls were assayed for 11 NAT1 alleles (NAT1*3, *4, *5, *10, *11, *14, *15, *16, *17, *19, and *22). The NAT1*4 allele was the predominant allele observed in this study population, accounting for 73.2% (72.4% in cases versus 73.8% in controls) of the total alleles analyzed. Compared to controls, breast cancer cases had a slightly higher frequency of the NAT1*10 allele (18.8% in cases versus 17.3% in controls) and a substantially higher frequency of the NAT1*11 allele (3.6% versus 1.2%). In multivariate analyses, we found a 30% [95% confidence interval (CI) = 0.8-1.9] elevated risk of breast cancer associated with the NAT1*10 allele and a nearly 4-fold (95% CI = 1.5-10.5) elevated risk associated with the NAT1*11 allele. The positive association of breast cancer with the NAT1*11 allele was more evident among smokers [odds ratio (OR) = 13.2, 95% CI = 1.5-116.0] and those who consumed a high level of red meat (OR = 6.1, 95% CI = 1.1-33.2) or consistently consumed their red meat well done (OR = 5.6, 95% CI = 0.5-62.7). The association of the NAT1*10 allele with breast cancer was mainly confined to former smokers (OR = 3.3, 95% CI = 1.2-9.5). These findings are consistent with a role for the NAT1 gene in the etiology of human breast cancer.