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PubMed1983

The role of the proton-motive force and electron flow in light-driven solute transport in Rhodopseudomonas sphaeroides.

The initial rate of uptake of alanine was studied in whole cells of Rhodopseudomonas sphaeroides under conditions such that the proton-motive force generated by light-induced cyclic electron transfer, was composed of the membrane potential only. The proton-motive force was varied by varying the light intensity or by pretreatment of the cells with the uncoupler carbonylcyanide p-trifluoromethoxyphenylhydrazone. At constant light intensity a threshold delta psi is required before alanine uptake occurs. Above this threshold value the rate of alanine uptake increases with the delta psi. The threshold value of the delta psi is higher the lower the light intensity. Under conditions of constant delta psi the rate of alanine uptake increases linearly with the light intensity. At low delta psi values a threshold light intensity is required which is higher the lower the delta psi. These results demonstrate that both a proton-motive force and electron transfer are required for alanine uptake.

Alanine↗
PubMed1986

Measurements of the proton motive force generated by cytochrome c oxidase from Bacillus subtilis in proteoliposomes and membrane vesicles.

Cytochrome c oxidase from Bacillus subtilis was reconstituted in liposomes and its energy-transducing properties were studied. The reconstitution procedure used included Ca2+-induced fusion of pre-formed membranes. The orientation of the enzyme in liposomes is influenced by the phospholipid composition of the membrane. Negatively charged phospholipids are essential for high oxidase activity and respiratory control. Analyses of the proteoliposomes by gel filtration, density gradient centrifugation and electron microscopy indicated a heterogeneity of the proteoliposomes with respect to size and respiratory control. Cytochrome c oxidase activity in the proteoliposomes resulted in the generation of a proton motive force, internally negative and alkaline. In the presence of the electron donor, ascorbate/N,N,N',N'-tetramethyl-p-phenylenediamine/cytochrome c or ascorbate/phenazine methosulphate, the reconstituted enzyme generated an electrical potential of 84 mV which was increased by the addition of nigericin to 95 mV and a pH gradient of 32 mV which was increased by the addition of valinomycin to 39 mV. Similar results were obtained with beef-heart cytochrome c oxidase reconstituted in liposomes. The maximal proton motive force which could be generated, assuming no endogenous ion leakage, varied over 110-140 mV. From this the efficiency of energy transduction by cytochrome c oxidase was calculated to be 18-23%, indicating that the oxidase is an efficient proton-motive-force-generating system.

Bacillus subtilis↗
PubMed1987

Physiological adaptations of anaerobic bacteria to low pH: metabolic control of proton motive force in Sarcina ventriculi.

Detailed physiological studies were done to compare the influence of environmental pH and fermentation end product formation on metabolism, growth, and proton motive force in Sarcina ventriculi. The kinetics of end product formation during glucose fermentation in unbuffered batch cultures shifted from hydrogen-acetate production to ethanol production as the medium pH dropped from 7.0 to 3.3. At a constant pH of 3.0, the production of acetate ceased when the accumulation of acetate in the medium reached 40 mmol/liter. At a constant pH of 7.0, acetate production continued throughout the entire growth time course. The in vivo hydrogenase activity was much higher in cells grown at pH 7.0 than at pH 3.0. The magnitude of the proton motive force increased in relation to a decrease of the medium pH from 7.5 to 3.0. When the organism was grown at pH 3.0, the cytoplasmic pH was 4.25 and the organism was unable to exclude acetic acid or butyric acid from the cytoplasm. Addition of acetic acid, but not hydrogen or ethanol, inhibited growth and resulted in proton motive force dissipation and the accumulation of acetic acid in the cytoplasm. The results indicate that S. ventriculi is an acidophile that can continue to produce ethanol at low cytoplasmic pH values. Both the ability to shift to ethanol production and the ability to continue to ferment glucose while cytoplasmic pH values are low adapt S. ventriculi for growth at low pH.

Acids↗
PubMed1994

Proton motive force-driven and ATP-dependent drug extrusion systems in multidrug-resistant Lactococcus lactis.

Three mutants of Lactococcus lactis subsp. lactis MG1363, termed EthR, DauR, and RhoR, were selected for resistance to high concentrations of ethidium bromide, daunomycin, and rhodamine 6G, respectively. These mutants were found to be cross resistant to a number of structurally and functionally unrelated drugs, among which were typical substrates of the mammalian multidrug transporter (P-glycoprotein) such as daunomycin, quinine, actinomycin D, gramicidin D, and rhodamine 6G. The three multidrug-resistant strains showed an increased rate of energy-dependent ethidium and daunomycin efflux compared with that of the wild-type strain. This suggests that resistance to these toxic compounds is at least partly due to active efflux. Efflux of ethidium from the EthR strain could occur against a 37-fold inwardly directed concentration gradient. In all strains, ethidium efflux was inhibited by reserpine, a well-known inhibitor of P-glycoprotein. Ionophores which selectively dissipate the membrane potential or the pH gradient across the membrane inhibited ethidium and daunomycin efflux in the wild-type strain, corresponding with a proton motive force-driven efflux system. The ethidium efflux system in the EthR strain, on the other hand, was inhibited by ortho-vanadate and not upon dissipation of the proton motive force, which suggests the involvement of ATP in the energization of transport. The partial inhibition of ethidium efflux by ortho-vanadate and nigericin in the DauR and RhoR strains suggest that a proton motive force-dependent and an ATP-dependent system are expressed simultaneously. This is the first report of an ATP-dependent transport system in prokaryotes which confers multidrug resistance to the organism.

Adenosine Triphosphate↗
PubMedDate not supplied

Female genital cutting: types, motives and perineal damage in laboring Egyptian women.

OBJECTIVES: To study the prevalence of female genital cutting (FGC) in a nulliparous population admitted for childbirth. In addition, the type of FGC, the motives supporting FGC and perineal damage associated with this practice were evaluated. SUBJECTS AND METHODS: A prospective cross-sectional study was conducted in the labor ward, Department of Obstetrics and Gynecology, Assiut University Hospital, Assiut, Egypt. Two hundred and fifty-four primigravid women in active labor were recruited over a period of 20 months. The subjects responded to a questionnaire and obstetric and pelvic examinations were carried out. The type of cut (circumcision) and extent of tissue removal were recorded. Data was gathered concerning possible motives for FGC, rates of episiotomy and incidence of perineal tears. RESULTS: All women recruited had been circumcised; 51% had type I cut and 49% had type II. Adherence to tradition was the most common motive for the operation (46.5%). Ninety-five percent of the study population had an episiotomy. The incidence of perineal tears was 1.6%. CONCLUSIONS: Female genital cutting (only types I and II) was confirmed in all patients in the study. There was a low incidence of perineal tears and a high episiotomy rate (95%). Episiotomy should be performed in all cases where FGC has made the vulva/vagina inelastic.

Adolescent↗
PubMed2005

Animal cruelty motivations: assessing demographic and situational influences.

Few studies have examined childhood and adolescent animal cruelty motives. Using a sample of 261 inmates surveyed at both medium and maximum security prisons ina southern state, the present study examined the impact of demographic attributes and situational factors relating specifically to a range of animal cruelty motivations. Almost half of the inmates who engaged in animal abuse reported committing some of the acts out of anger, whereas more than a third did so for fun. Regression analyses revealed that the most statistically salient variable in 7 of the 10 motivational models was whether animal cruelty was committed alone. Respondents who reported hurting or killing animals alone were more likely to commit the acts out of anger but less likely to have committed them to impress others, for sex, or to imitate others.

Adult↗
PubMed2006

The identification of sexual and violent motivations in men who assault women: implication for treatment.

A qualitative analysis of interview data with 41 rapists determined that five implicit theories (ITs) underlie rapists' offense supportive beliefs/feelings/motives: (a) dangerous world (DW)-where men have feelings of generalized anger and/or resentment toward others; (b) women are dangerous-where men hold a set of attitudes that are hostile toward women; (c) women as sexual objects (WSO)-where women are seen as primarily sexual objects; (d) male sex drive is uncontrollable-where sexual urges are seen all consuming; (e) entitlement-where men feel that they can do exactly what they want. Consideration of whether DW or WSO ITs were present or absent indicated that three main groups could be identified: Group 1: violently motivated-presence of DW and/or absence of WSO; Group 2: sexually motivated-presence of WSO and/or absence of DW; Group 3: sadistically motivated-presence of DW and WSO. These results are discussed in terms of treatment needs of rapists.

Adult↗
PubMed2006

Compliance and intimacy: young adults' attempts to motivate health-promoting behaviors by romantic partners.

Benefits of relational intimacy on health may derive from its influence on the success of verbal attempts to motivate romantic partners' compliance with suggested protective behaviors. The intimacy levels of 209 participants' romantic relationships were assessed, as were motivations to change 4 health behaviors in response to 8 appeal strategies. Intimacy had significant impacts on the estimated effectiveness of several appeals. Also, as intimacy increased, caring replaced the provision of health information as the most efficacious strategy for motivating dietary modification. Overall, appeals seeking safer sex and those employing liking, caring, and threat strategies were rated as generally most effective.

Adult↗
PubMed1984

A revised measure of approval motivation and its relationship to social desirability.

Existing measures of approval motivation attempt to assess this dimension of personality indirectly through evaluation of socially desirable response tendencies. The Martin-Larsen Approval Motivation (MLAM) Scale takes a more direct approach by focusing on individual differences in need for social approval. Since the original version of the MLAM scale is subject to acquiescence response bias, fully balanced and partially balanced scales were created to minimize this response style. Results indicated that the revised measures arc equivalent to the original version and that balancing affects the magnitude but not the pattern of correlates with other scales. Comparisons with the Marlowe-Crowne Social Desirability (MCSD) Scale revealed a divergent pattern of correlates with several measures of personality suggesting a basic difference between the MLAM and MCSD in their conceptualization of approval motivation.

Journal Article↗
PubMed1997

Performance effects of motivational state: a meta-analysis.

Researchers (e.g., Butler, 1987; Elliott & Dweck, 1988; Grolnick & Ryan, 1987) have recently studied the impact of two different motivational states and have hypothesized that attempting to attain mastev (learning goal) leads to better performance than attempting to demonstrate that one has high ability (performance goal). This article presents a meta-analysis of research in which motivational states are manipulated and confirms that learning goals lead to better performance than do performance goals. The results also indicate that the learning goal advantage may be limited to relatively complex tasks and that the learning goal advantage is smaller for young children than for older individuals. Further, the learning goal advantage was larger when learning goals were moderately pressuring and when participants were tested alone. Theoretical integration of various theories of motivation and practical implications of the findings are discussed.

Journal Article↗
PubMed1999

Achievement goals and intrinsic motivation: a meta-analytic review.

This article presents a meta-analysis of the experimental literature that has examined the effect of performance and mastery achievement goals on intrinsic motivation. Summary analyses provided support for the hypothesis that the pursuit of performance goals has an undermining effect on intrinsic motivation relative to the pursuit of mastery goals. Moderator analyses were conducted in an attempt to explain significant variation in the magnitude and direction of this effect across studies. Results indicated that the undermining effect of performance goals relative to mastery goals was contingent on whether participants received confirming or nonconfirming competence feedback, and on whether the experimental procedures induced a performance-approach or performance-avoidance orientation. These findings provide conceptual clarity to the literature on achievement goals and intrinsic motivation and suggest numerous avenues for subsequent empirical work.

Journal Article↗
PubMed2004

Moving beyond disclosure: women's perspectives on barriers and motivators to seeking assistance for intimate partner violence.

To investigate women's perceptions of motivators and barriers to seeking help or accessing intimate partner violence (IPV), services six focus groups were conducted in rural and urban settings in North Carolina between June and August of 2002. Coding and theme analysis were used to summarize themes among the 67 focus group participants. The majority of participants were African-American (87%). Participants reported three main categories of motivators: gaining knowledge; reaching an emotional or physical breaking point; and growing concern about children's safety. Participants reported six main categories of barriers: pressure not to talk about, or address IPV; failure to recognize events as IPV, or that IPV was wrong; self-doubt and low self-esteem; fear of losses; fear of perpetrator; or desire to protect the perpetrator. This study documents the difficulties that women face accessing or using services related to IPV. We need to address perceived barriers and better use the opportunity when women experience motivation to seek help and access services.

Adult↗
PubMed1993

Using incentives to motivate women to seek prenatal care: an effective outreach strategy.

Expanded Medicaid eligibility and case-managed care have contributed to improved birth outcomes and reduced Medicaid expenditures in Alabama. In 1990, 26.5 percent of all women delayed entry to care until the fourth month of pregnancy or later. Additionally, more than 1,000 women in the state received no care at all. In many of these cases, women perceived prenatal care as unimportant or unnecessary until later in pregnancy. As a result, the Alabama Medicaid Agency developed Healthy Beginnings, an incentive and awareness program which utilizes coupons to motivate women to seek prenatal care. Pregnant women can receive the coupon book (worth about $300) simply by dialing a toll-free number. To take advantage of the free gifts and discounts, expectant mothers must visit a private physician or health clinic and have their coupons validated monthly. The project was initiated in August, 1990, and already there is clear evidence that the use of incentives represents a viable outreach strategy to motivate poor and uninsured women to seek care. In the program's first year, more than 20,000 women received the coupons, of which 78 percent were Medicaid recipients, uninsured or in a presumptive (Medicaid) eligibility period. Focus group studies, field visits and a survey were used to evaluate the effectiveness of the new program. Preliminary data analysis has revealed that the incentive program may be a significant factor in motivating women to seek early and continuous prenatal care.

Alabama↗
PubMedDate not supplied

Biological motivations in the neurodynamic structure of psychopathological states (experimental approach).

Some trigger mechanisms of pathological and biological motivations were investigated in experimental models of animal behavior (feeding, drinking, stereotypic acts, experimental alcoholism, and so on), as well as high level of brain-specific molecular synthesis responsible for development of pathological motivations. Neurophysiological processes transforming some biological drives to pathological motivations are described and discussed.

Alcoholism↗
PubMed2001

[The significance of a reminder and physician's motivation for the response rate of a questionnaire survey in general practice].

The use of a mailed reminder to improve the response rate in a questionnaire survey was analysed in a general practice multicentre survey in Denmark, Norway, and the Netherlands. In total 14 general practitioners (GP's) handed out the questionnaire to 650 adult patients. A randomized sample of the patients who did not respond after three weeks received a reminder including a new questionnaire. In the group that received a reminder the response rate was significantly higher compared with the group that did not (79% vs. 62%). In Denmark, two of the four participating GP's were specially motivated. The response rate for these GP's was significantly higher compared to the normally motivated GP's (91% vs. 71%). Specially motivated GP's can increase the response rate and thereby minimise the effect of the reminder.

Adult↗
PubMed2001

Consumer motivation towards purchasing fruit from integrated production in Belgium.

Consumer concerns about food safety have been steadily growing during the last decade. Along with the recognition of the increasing power from the consumer side of food chains, this has forced agricultural producers to innovate and adapt their production methods. One of those developments is integrated production of pip fruit (IFP). This research analyses and presents motivational structures of consumers towards purchasing IP fruit in Belgium. The research methodology builds on means-end-chain (MEC) theory, with data collected through personal laddering interviews with consumers. A hierarchical value map, indicating motivational structures for farm shop purchase of IP-labelled apples, is presented. IP-apple buyers pursue typical values, with health being paramount. The findings reveal interactions between market channel characteristics and product attributes, including characteristics that refer to production methods. Also, the study shows how outlet choice influences the perception and the motivation structure of the respondents for the specific product, fresh fruit in this case. From the findings, two sets of implications are set forth. First, marketing implications pertaining to advertising through the application of the "Means-End Conceptualization of the Components of Advertising Strategy" or MECCAS model. Second, implications to producers with respect to adapting their production methods to the needs and wants of the present end consumers.

Advertising↗
PubMed2004

[Communication strategies to motivate patients to follow doctor's advice].

The growing attention to the preventive aspects of health care has raised the question how to motivate patients to modify potentially health damaging habits such as smoking, alcohol abuse, wrong diet or poor exercise. The present paper examines the theory and the techniques of the motivational interview and proposes practical examples which illustrate how the physician may overcome patient's resistance. The authors describe the principal aspects of the process of motivational change and some of the corresponding attitudes and skills which the physician has to adopt in each phase of this process. The basic assumptions are that the patient is the main agent of change and that the physician's task is to facilitate this process and to sustain the patient's efforts.

Communication↗
PubMed2004

[Evoked activity of the cat hypothalamus and amygdala under food motivation and in emotional stress].

Amplitude-latency characteristics of auditory evoked potentials (EPs) recorded in bilateral points of the lateral hypothalamus and amygdala were studied under food motivation, in emotional stress (presentation of dogs) and tentative reactions. In the state of hunger, as compared with safety, the latencies of P1, N2 components of EP in hypothalamus, and P1, N2, N3 in amygdala were decreased and their amplitudes were changed. Changes in the left side of both structures were more pronounced. During presentation of dogs, decreases of latencies of all EP components including N1 occurred in hypothalamus and amygdala, changes in hypothalamic potentials were more pronounced on the right side, whereas in the amygdala--on the left side. During tentative responses to emotional-neutral stimuli, the latency of EP increased. It was concluded that sensory reactivity of hypothalamus and amygdala increased in motivational-emotional states. It was supposed that the side of dominance of structure may be related both to the factors of active or passive behavior during fear and the genesis of emotion (motivational or informational).

Amygdala↗