A bacterial sense of touch: T4P retraction motor as a means of surface sensing by Pseudomonas aeruginosa PA14.

Most microbial cells found in nature exist in matrix-covered, surface-attached communities known as biofilms. This mode of growth is initiated by the ability of the microbe to sense a surface on which to grow. The opportunistic pathogen Pseudomonas aeruginosa (Pa) PA14 utilizes a single polar flagellum and type 4 pili (T4P) to sense surfaces. For Pa, T4P-dependent "twitching" motility is characterized by effectively pulling the cell across a surface through a complex process of cooperative binding, pulling, and unbinding. T4P retraction is powered by hexameric ATPases. Pa cells that have engaged a surface increase production of the second messenger cyclic AMP (cAMP) over multiple generations via the Pil-Chp system. This rise in cAMP allows cells and their progeny to become better adapted for surface attachment and activates virulence pathways through the cAMP-binding transcription factor Vfr. While many studies have focused on mechanisms of T4P twitching and regulation of T4P production and function by the Pil-Chp system, the mechanism by which Pa senses and relays a surface-engagement signal to the cell is still an open question. Here we review the current state of the surface sensing literature for Pa, with a focus on T4P, and propose an integrated model of surface sensing whereby the retraction motor PilT senses and relays the signal to the Pil-Chp system via PilJ to drive cAMP production and adaptation to a surface lifestyle.

Evidence for the Type IV Pilus Retraction Motor PilT as a Component of the Surface Sensing System in Pseudomonas aeruginosa.

Biofilm formation begins when bacteria contacting a surface induce cellular changes to become better adapted for surface growth. One of the first changes to occur for Pseudomonas aeruginosa after surface contact is an increase in the nucleotide second messenger 3',5'-cyclic AMP (cAMP). It has been demonstrated that this increase in intracellular cAMP is dependent on functional type IV pili (T4P) relaying a signal to the Pil-Chp system, but the mechanism by which this signal is transduced remains poorly understood. Here, we investigate the role of the type IV pilus retraction motor PilT in sensing a surface and relaying that signal to cAMP production. We show that mutations in PilT, and in particular those impacting the ATPase activity of this motor protein, reduce surface-dependent cAMP production. We identify a novel interaction between PilT and PilJ, a member of the Pil-Chp system, and propose a new model whereby P. aeruginosa uses its PilT retraction motor to sense a surface and to relay that signal via PilJ to increased production of cAMP. We discuss these findings in light of current T4P-dependent surface sensing models for P. aeruginosa. IMPORTANCE T4P are cellular appendages that allow P. aeruginosa to sense a surface, leading to the production of cAMP. This second messenger not only activates virulence pathways but leads to further surface adaptation and irreversible attachment of cells. Here, we demonstrate the importance of the retraction motor PilT in surface sensing. We also present a new surface sensing model in P. aeruginosa whereby the T4P retraction motor PilT senses and transmits the surface signal, likely via its ATPase domain and interaction with PilJ, to mediate production of the second messenger cAMP.

Evidence for the Type IV Pili Retraction Motor PilT as a Component of the Surface Sensing System in Pseudomonas aeruginosa.

Biofilm formation begins when bacteria contacting a surface induce cellular changes to become better adapted for surface growth. One of the first changes to occur for Pseudomonas aeruginosa after surface contact is an increase in the nucleotide second messenger 3',5'-cyclic adenosine monophosphate (cAMP). It has been demonstrated that this increase in intracellular cAMP is dependent on functional Type IV pili (T4P) relaying a signal to the Pil-Chp system, but the mechanism by which this signal is transduced remains poorly understood. Here, we investigate the role of the Type IV pili retraction motor PilT in sensing a surface and relaying that signal to cAMP production. We show that mutations affecting the structure of PilT and in particular ATPase activity of this motor protein, reduce surface-dependent cAMP production. We identify a novel interaction between PilT and PilJ, a member of the Pil-Chp system, and propose a new model whereby P. aeruginosa uses its retraction motor to sense a surface and to relay that signal via PilJ to increased production of cAMP. We discuss these findings in light of current TFP-dependent surface sensing models for P. aeruginosa . Importance: T4P are cellular appendages that allow P. aeruginosa to sense a surface leading to the production of cAMP. This second messenger not only activates virulence pathways but leads to further surface adaptation and irreversible attachment of cells. Here, we demonstrate the importance of the retraction motor PilT in surface sensing. We also present a new surface sensing model in P. aeruginosa whereby the T4P retraction motor PilT senses and transmits the surface signal, likely via its ATPase domain and interaction with PilJ, to mediate production of the second messenger cAMP.

Corn oil intake favorably impacts lipoprotein cholesterol, apolipoprotein and lipoprotein particle levels compared with extra-virgin olive oil.

BACKGROUND: Corn oil (CO) and extra-virgin olive oil (EVOO) are rich sources of unsaturated fatty acids (UFA), but UFA profiles differ among oils, which may affect lipoprotein levels. OBJECTIVES: The objective of this study was to assess the effects of CO versus EVOO intake on fasting lipoprotein and subfraction cholesterol levels, apolipoprotein (apo) A1, apo B, and low-density lipoprotein particle concentrations in men and women. SUBJECTS/METHODS: As part of a weight maintenance diet, men and women were provided with food items prepared with 54 g per day of CO or EVOO (21-day treatment, 21-day washout) in a randomized, double-blind, controlled-feeding, crossover trial. Fasting lipoprotein cholesterol and related variables were determined with density gradient ultracentrifugation. RESULTS: Among the 54 completers, CO reduced total cholesterol, low-density lipoprotein cholesterol (LDL-C), very low-density lipoprotein cholesterol (VLDL-C), non-high-density lipoprotein cholesterol (non-HDL-C), apo B and LDL particle concentration to a greater extent compared with EVOO intake. Changes in LDL-C and VLDL-C contributed to the larger reduction in non-HDL-C with CO compared with EVOO intake (-0.39 mmol/l vs -0.04 mmol/l; P<0.001). The larger reduction in LDL-C by CO intake was attributable to changes (P<0.05) caused by CO vs EVOO in large LDL1+2-C (-0.22 mmol/l) and intermediate-density lipoprotein cholesterol (-0.12 mmol/l). HDL-C responses did not differ between treatments, but apo A1 increased more with EVOO compared with CO intake (4.6 versus 0.7 mg/dl, respectively, P=0.016). CONCLUSIONS: CO intake reduced atherogenic lipoprotein cholesterol and particle concentrations to a larger extent than did EVOO, which may have implications for cardiovascular disease risk.

Communicating dietary guidelines for Americans: room for improvement.

This qualitative study examines consumers' attitudes about key messages, alternative messages, and various formats of the 1995 US Dietary Guidelines for Americans. Five focus groups were conducted using a discussion guide based on previous research and the research concerns of the 1995 Dietary Guidelines Advisory Committee. The presentation orders of the guidelines, guideline alternatives, and formats were varied to prevent bias. Forty consumers (age range, 25 to 43 years) participated: 3 groups of women and 2 groups of men. Participants were not familiar with the Dietary Guidelines but had heard some messages. Consumers were confused by several guideline messages. First, the messages to "Maintain or improve your weight" and "Balance the food you eat with physical activity" did not make sense to them. Second, respondents were confused by the term "balance" in several different contexts. The participants most preferred a shortened format, followed by a 2-tiered or grouped format, with the 1995 list of Dietary Guidelines falling last. Most of the Dietary Guidelines could be better communicated to the public using shorter, clearer messages, especially for the weight and physical activity, and fat guidelines. Decreasing the number of guidelines or using a tiered/grouped format could make the Dietary Guidelines more useful to consumers.

Genetics, surnames, grandparents' nationalities, and ethnic admixture in Southern Brazil: do the patterns of variation coincide?

A total of 2,708 individuals from the European-derived population of Rio Grande do Sul, divided into seven mesoregions, and of 226 individuals of similar origin from Santa Catarina were studied. Seventeen protein genetic systems, as well as grandparents' nationalities, individuals' surnames, and interethnic admixture were investigated. The alleles which presented the highest and lowest differences were GLO1*2 (16 per cent) and PGD*A (2 per cent), respectively, but in general no significant genetic differences were found among mesoregions. The values observed were generally those expected for individuals of European descent, with the largest difference being a lower prevalence (34-39per cent) of P*1. Significant heterogeneity among mesoregions was observed for the other variables considered, and was consistent with historical records. The Amerindian contribution to the gene pool of European-derived subjects in Rio Grande do Sul was estimated to be as high as 11 per cent. Based on the four data sets, the most general finding was a tendency for a northeast-southwest separation of the populations studied. Seven significant phenotype associations between systems were observed at the 5 per cent level (three at the 0.1 per cent level). Of the latter, the two most interesting (since they were also observed in other studies) were MNSs/Duffy and Rh/ACP.

Health claims: history, current regulatory status, and consumer research.

During the past 13 years regulatory and consumer communications policies on health claims have been hotly debated and have evolved from a nonregulatory action policy by which health claims were written by manufacturers to one in which claims are carefully proscribed and legally allowed by regulatory agencies. Unfortunately, health claims are not used to full public health potential. This review examines the scientific literature to determine the most effective way to communicate health claims to consumers. The results of health claims studies suggest an evolution in consumer preferences: from complete non-product-specific information in the middle to late 1980s to shorter product-specific claims in 1995 and 1996. Comprehension research suggests that shorter health claims communicate most effectively. Related label research shows that effective messages suggest action, contain text, and graphics, and are placed on the front panel. In conclusion, effective health claims: Are concise Relate to a consumer need or task to be solved Appear on the front panel Combine text and graphics using color Provide an additional benefit beyond the label (e.g., increase the production and availability of more nutritious products and increase consumers' knowledge of nutrition and health).

Peer counselor program increases breastfeeding rates in Utah Native American WIC population.

Lack of breastfeeding promotion and support hinder successful breastfeeding. In this study, a breastfeeding peer counselor program improved both the initiation rate and duration of breastfeeding up to three months postpartum among Native American WIC participants. Trained peer counselors contacted subjects prenatally, and at one, two, and four to six weeks postpartum. Breastfeeding rates for the experimental group were compared to historical controls. Women in the peer counselor group who had complete data for three months (n = 41) had a higher rate of breastfeeding than the control group (n = 67) at initiation (84 percent vs. 70 percent; p = 0.05) and at three months postpartum (49 percent vs. 36 percent; p = 0.08).

Effect of dronabinol on nutritional status in HIV infection.

OBJECTIVE: To examine the effect of dronabinol (delta-9-tetrahydrocannabinol) on appetite and nutritional status in patients with symptomatic HIV infection and weight loss. DESIGN: Double-blind, randomized, placebo-controlled, crossover trial with two five-week treatment periods separated by a two-week washout period. Patients received dronabinol 5 mg twice daily before meals or placebo. SETTING: A university-based HIV/AIDS clinic and a large infectious disease private practice largely devoted to care of patients with HIV. PARTICIPANTS: Twelve HIV-infected patients who had had at least a 2.25-kg weight loss participated in the study. Five patients completed the protocol, and seven withdrew (two because of drug intolerance, two because of disease progression, two because of noncompliance, and one because of experimental antiretroviral therapy). MAIN OUTCOME MEASURES: Main outcome measures included caloric intake, weight, percent body fat, serum prealbumin, and symptom distress. RESULTS: During dronabinol treatment, subjects experienced increased percent body fat (one percent, p = 0.04); decreased symptom distress (p = 0.04); and trends toward weight gain (0.5 kg, p = 0.13), increased prealbumin (29.0 mg/L, p = 0.11), and improved appetite score (p = 0.14). CONCLUSIONS: In a selected group of HIV-infected patients with weight loss, short-term treatment with dronabinol may result in improvement in nutritional status and symptom distress.

Nutrition labels in bar graph format deemed most useful for consumer purchase decisions using adaptive conjoint analysis.

This study estimated the effects of changing multiple levels and combinations of nutrition information format, load, expression, and order on consumers' perceptions of label usefulness in purchase decisions using adaptive conjoint analysis. A shopping mall intercept survey, which was administered by a marketing research firm, assessed consumer preferences for 12 label alternatives produced on Campbell's soup cans to portray nutrition information realistically; 252 of 258 respondents completed the computer interactive interview. Consumers significantly preferred the bar graph format to the bar graph/nutrient density and traditional label formats. Consumers considered the bar graph/nutrient density format to be as useful as the traditional label format. There was a highly significant difference among the three levels of information load; the most information load was preferred regardless of nutrient importance. Consumers significantly preferred nutrition information stated in absolute numbers and percentages vs in absolute numbers only in traditional, or in percentages only expressions. There was a significant difference between consumer preferences for the two types of information order. The findings indicate that consumers clearly preferred the nutrition label that displayed all nutrient values using a bar graph format, offered the most information load, and expressed nutrient values using both absolute numbers and percentages. Consumers also preferred nutrition information rearranged in an order that grouped nutrients that should be consumed in adequate amounts on the top, calories in the middle, and nutrients that should be consumed in lesser amounts on the bottom of the label.

Review of nutrition labeling formats.

This article examines nutrition labeling history as well as the findings of nine research studies of nutrition labeling formats. Nutrition labeling regulations were announced in 1973 and have been periodically amended since then. In response to requests from consumers and health care professionals for revision of the labeling system, the Food and Drug Administration initiated a three-phase plan for reform of nutrition labeling in 1990. President Bush signed the Nutrition Labeling and Education Act in November 1990. Literature analysis revealed that only nine studies with an experimental design have focused on nutrition labeling since 1971. Four were conducted before 1975, which was the year that nutrition labeling was officially implemented, two were conducted in 1980, and three were conducted after 1986. Only two of the nine studies supported the traditional label format mandated by the Code of Federal Regulations, and one study partially supported it. Four of the nine studies that evaluated graphic presentations of nutrition information found that consumer comprehension of nutrition information was improved with a graphic format for nutrition labeling: three studies supported the use of bar graphs and one study supported the use of a pie chart. Full disclosure (ie, complete nutrient and ingredient labeling) was preferred by consumers in two of the three studies that examined this variable. The third study supported three types of information disclosure dependent upon socioeconomic class. In those studies that tested graphics, a bar graph format was significantly preferred and showed better consumer comprehension than the traditional format.

Consumers' knowledge, understanding, and attitudes toward health claims on food labels.

The purpose of this study was to assess consumers' knowledge of current fiber recommendations and their attitudes, understanding, and awareness of health claims on breakfast cereal labels. An incidental sample of 241 respondents was drawn from four grocery stores of a local chain in Utah. Data were collected using a computerized interviewing system. The results suggested that consumers with higher education levels had a better understanding of diet-disease-related messages and a more positive attitude toward health messages on food labels. Knowledge of fiber was significantly correlated with positive attitudes toward health messages and understanding of health messages. Overall, attitudes toward placing diet-disease-related messages on food labels were positive. On a scale of 1 through 250, the mean score was 182.5 +/- 37.5 standard deviation (73%). Consumer knowledge of fiber was low. Out of 15 possible points, the mean score for fiber knowledge questions was 8.8 +/- 2.1 (59%). Consumers were more familiar with the role fiber may play in the prevention or treatment of certain diseases or conditions than with sources, classifications, and recommended intakes of fiber. Understanding of health messages was relatively low (45%). Whereas consumer attitudes toward health messages on food labels were positive, consumers (especially less-educated consumers) did not appear to understand the messages well. These results reiterate the concern for public policymakers to exercise caution and ensure that health messages on food labels are responsible and accurate. The results should also remind dietetic practitioners, who are the nutrition experts, of their continual role in providing and ensuring accurate nutrition education to the public.

Relationship between nutrient intake, body mass index, menstrual function, and ballet injury.

The effects of inadequate nutrition, menstrual dysfunction, and low body weight on the injury rate of ballerinas were studied. Forty-nine female ballet dancers, mean age 18.7 years, completed food frequency and injury questionnaires. Subjects were placed in one of two groups: those with an intake less than 70% of the Recommended Dietary Allowances (RDA) for key nutrients and those with an intake greater than 70% of the RDA for key nutrients. Sixty-nine percent of the dancers had intakes less than 70% of the RDA and were randomly assigned to either a vitamin/mineral supplement or to placebo for 6 months. The remaining dancers with diets adequate (greater than 70% RDA) in key nutrients received no treatment. All groups were questioned monthly about the incidence, severity, and nature of ballet injuries. Information regarding menses and height and weight was obtained. There were no significant differences in the severity or type of injuries among the dancers in the supplement, placebo, or no treatment groups. Dancers with abnormal menses had more bone injuries (mean = 15.00) than normally menstruating dancers (mean = 4.97) (p less than .05). Dancers with a Body Mass Index less than 19.0 spent more days with a low-grade injury (mean = 24.05) than dancers with a greater BMI (mean = 11.63) (p less than .05). There appears to be a relationship between dance injuries and both BMI and menstrual function.

What characterizes elderly women who overuse vitamin and mineral supplements?

This study has identified some potentially important characteristics of elderly women who overuse vitamin and mineral supplements. These women tended to live alone and to have medical problems. The supplements were usually self-prescribed and purchased in a drugstore. The sources of information that supported supplement use were primarily the print media and family and friends rather than health professionals. Other studies have made similar findings. The degree of IHLC orientation failed to predict the amount of supplement use, although IHLC was shown to be useful in a recent study that included both young and elderly women. Thus, from our perspective, the identification of possible overusers of supplements should begin with elderly women who have health problems and live alone; point-of-purchase information should be targeted to drugstores. In this study and in other, either the actual reasons for supplement use were often inappropriate or the diets were adequate in many of the vitamins taken by supplements, such as vitamins A and C. Thus, education for elderly women that stresses the appropriate reasons for nutrient supplement use is clearly needed so that a correct link between nutrition need and use always is maintained. The high IHLC scores suggest that the majority of women in this study want to make their own decisions about their health. Given better information, overusers of supplements might instead choose a more reasonable approach for improving their diets. Dietitians/nutritionists were not usually used as a source of nutrition information by the elderly women in this study.(ABSTRACT TRUNCATED AT 250 WORDS)