Taxonomy of \u3cem\u3eStreptanthus\u3c/em\u3e sect. \u3cem\u3eBiennes\u3c/em\u3e, the \u3cem\u3eStreptanthus morrisonii\u3c/em\u3e complex (Brassicaceae)

The Streptanthus morrisonii complex is a six-taxon group of closely related serpentine rock outcrop endemics from Lake, Napa, and Sonoma counties of California, USA. Two new subspecies (S. morrisonii subsp. kruckebergii and S. brachiatus subsp. hoffmanii) from Lake County, California, are described. The relationship of these taxa to others in the section is reviewed and descriptions and a key are provided

A Lower Limb Prosthesis with Active Alignment for Reduced Limb Loading

Over the past decade, the growing field of robotics has created new possibilities in lower limb prostheses. The focus of these new prostheses has been replicating the dynamics of the lost limb in order to restore gait of individuals with lower limb amputations to healthy norms. This places demanding loads on the residual limb. Compensation by the rest of body is high, causes overloading of intact joints and can lead to deterioration of mobility and overall health. Abnormalities remain present in the person’s gait, stemming from the loading of soft tissue and the altered anatomy of the affected limb. In this dissertation, an experimental prosthesis is developed with systematic, simulation based techniques. Kinematics and kinetics of the prosthesis design are altered in order to actively realign the limb in relation to the center of pressure during stance, allowing positive power to be generated by the prosthesis while actively reducing the magnitude of the sagittal moment transferred to the residual limb. Initial findings show that during walking with the experimental device compared to a daily use prosthesis, peak pressures on the residual limb are lowered by over 10% while maintaining walking speed

Model of Maladaptive Control: Understanding the Link between Parents’ Psychological Control and Youth Aggression Problems

Research shows that parental psychological control is associated with youth aggression in peer relationships. This includes various aggression roles (aggression and victimization), forms (overt and relational), and functions (proactive and reactive). The current study examined the role of two youth individual traits, Machiavellianism and dysregulation, in the association between psychological control and youth aggression. A sample of 142 participants (age M = 15.4, SD = 1.13, 93% male, 82% African-American) were recruited from several juvenile detention facilities in Louisiana. Participants completed a battery of questionnaires, including self-reports of Machiavellianism, dysregulation, aggression, victimization, and parental psychological control. Bootstrap analyses indicated youth Machiavellianism partially mediated the associations between psychological control and the aggression roles, forms, and functions. Youth dysregulation partially mediated the associations between psychological control and the aggression roles and forms. For the aggression functions, dysregulation partially mediated the association between psychological control and reactive aggression, and fully mediated the association between psychological control and proactive aggression. Regression analyses indicated psychological control and dysregulation were more strongly associated with reactive aggression than proactive aggression. Findings demonstrate the importance of the youth individual traits, Machiavellianism and dysregulation, in explaining the association between psychological control and youth aggression problems. These findings have implications for youth interventions, in that these individual traits may be useful targets to help decrease bullying and aggressive behaviors in peer relationships

Model of Maladaptive Control: Understanding the Link between Parents’ Psychological Control and Youth Aggression Problems

Research shows that parental psychological control is associated with youth aggression in peer relationships. This includes various aggression roles (aggression and victimization), forms (overt and relational), and functions (proactive and reactive). The current study examined the role of two youth individual traits, Machiavellianism and dysregulation, in the association between psychological control and youth aggression. A sample of 142 participants (age M = 15.4, SD = 1.13, 93% male, 82% African-American) were recruited from several juvenile detention facilities in Louisiana. Participants completed a battery of questionnaires, including self-reports of Machiavellianism, dysregulation, aggression, victimization, and parental psychological control. Bootstrap analyses indicated youth Machiavellianism partially mediated the associations between psychological control and the aggression roles, forms, and functions. Youth dysregulation partially mediated the associations between psychological control and the aggression roles and forms. For the aggression functions, dysregulation partially mediated the association between psychological control and reactive aggression, and fully mediated the association between psychological control and proactive aggression. Regression analyses indicated psychological control and dysregulation were more strongly associated with reactive aggression than proactive aggression. Findings demonstrate the importance of the youth individual traits, Machiavellianism and dysregulation, in explaining the association between psychological control and youth aggression problems. These findings have implications for youth interventions, in that these individual traits may be useful targets to help decrease bullying and aggressive behaviors in peer relationships

A Systematic Literature Review of the Relationship Between Alcohol Consumption and Highly Active Anti-Retroviral Therapy (HAART) in Patients Diagnosed with HIV/AIDS

According to the Global Information System on Alcohol and Health (GISAH), alcohol consumption causes more than 2.5 million deaths annually. This organization also attributes more than sixty different diseases in which alcoholism plays a significant role. Such diseases include the Human Immunodeficiency Virus (HIV) and Acquired Immune Deficiency Syndrome (AIDS) (WHO, 2014). There are over 50,000 new cases of HIV reported each year. In the United States, it is estimated that more than 1.1 million people are infected with HIV, and about one in six people are completely unaware that they are infected (CDC.gov, 2013). A systematic literature review was done on twenty different studies to see the effects that the consumption of alcohol may have on adherence to highly active antiretroviral therapy (HAART) and the progression of HIV. This literature review examined these effects by looking at CD4+ cell levels, viral load, disease progression, and early mortality rates. In the results, it was shown that there may be a possible correlation between the consumption of alcohol and HAART non-adherence, as well as the consumption of alcohol causing disease progression and early death. This review also found that several different studies considered HAART non-adherence to be a multifactorial issue, which should be further researched to help with the treatment of HIV. In conclusion, an assessment of the consumption of alcohol should be done in all patients diagnosed with HIV/AIDS. Patient teaching is needed to teach about the possible effects that alcohol may have on HAART, and referral to support groups is needed to help with adherence to HAART therapy. Prevention strategies should be formed to help decrease the spread of HIV/AIDS in the United States

Positive and Negative Parenting Strategies, Parental Psychopathology, and Relational Aggression in Youth

This study examined the mediating role of parental psychological control on the association between parental psychopathology and youth relational aggression in a community sample of 118 adolescents (aged 11-17) and their parents. Additionally, an analysis was conducted to examine the moderating role of positive parenting on the association between parental psychopathology and relational aggression. Further analyses controlled for overt aggression and examined effects of youth gender. Results suggest psychological control partially mediates the association between parental psychopathology and relational aggression. The overall mediation was not significant after controlling for overt aggression; however, the association between psychological control and relational aggression remained significant. The moderation was not significant. Parental psychopathology interacted with gender; specifically, psychopathology was significantly associated with relational aggression only for boys. Findings demonstrate the complexity of associations between different parenting variables and relational aggression, and the necessity of assessing the effects of overt aggression and gender

Positive and Negative Parenting Strategies, Parental Psychopathology, and Relational Aggression in Youth

This study examined the mediating role of parental psychological control on the association between parental psychopathology and youth relational aggression in a community sample of 118 adolescents (aged 11-17) and their parents. Additionally, an analysis was conducted to examine the moderating role of positive parenting on the association between parental psychopathology and relational aggression. Further analyses controlled for overt aggression and examined effects of youth gender. Results suggest psychological control partially mediates the association between parental psychopathology and relational aggression. The overall mediation was not significant after controlling for overt aggression; however, the association between psychological control and relational aggression remained significant. The moderation was not significant. Parental psychopathology interacted with gender; specifically, psychopathology was significantly associated with relational aggression only for boys. Findings demonstrate the complexity of associations between different parenting variables and relational aggression, and the necessity of assessing the effects of overt aggression and gender

Social construction of the middle class : class identification and class images of young Canadians

There is a contradiction between some of the theoretical issues regarding class and the results of subjective class identification research in the United States and in Canada. Arguments concerning the decline of the middle class and debates regarding the validity of the concept of class are met by a consistent self-identification of a majority of the population as middle-class. The aim of this thesis is to help us understand the apparent contradiction by considering how some young Canadians identify as and construct images of the middle class. Two hundred and forty nine undergraduate students from two Ontarian Universities completed a questionnaire comprised of open-ended and multiple choice questions. Results indicate that: 1) Participants in this study have vivid and salient images of who is and who is not, in their view, a member of the middle class; 2) Economic criteria are frequently used, but these are most often stated in qualified terms and combined with criteria concerning social and cultural capital or life style and values; 3) Some redundant economic criteria construct what could be seen as the "middle-class cocoon," a composite image of financial well-being, conservative spending patterns, feelings of security, and a strong work ethic; 4) Criteria regarding social and cultural capital or life style and values construct an image of a large and dominant middle class from which, on the other hand most of the population would be excluded, according to judgmental criteria; 5) Indications of a relationship between class and other aspects of social identity such as gender and ethnicity were not conclusive, but responses to a few of the questions indicate a need for further investigation. At the end of this process, we find a three-level class structure in which the middle class distinguishes itself from the upper class on the basis of ascribed criteria and from the lower class on the basis of achieved criteria. The middle class earns its status above the lower class and is not part of the upper class only because of fate. By the combination of a claim to size and inclusion with a set of selective and judgmental criteria, the middle class is socially constructed as an "exclusive majority.

Dietary calcium as a possible anti-promoter of colon carcinogenesis

SUMMARYColon cancer is the second-most common malignancy in both males and females and is strongly related to environmental factors of which diet seems to be the most important one. Dietary fat is positively correlated with the incidence of colon cancer whereas dietary fibre and dietary calcium seem to be negatively associated with the risk of colon cancer. The development of colon cancer can genetically and histologically be characterized in different phases which may offer several oppertunities for dietary intervention. A high intake of dietary fat promotes colon cancer in tumor-induction models whereas dietary calcium counteracts this promotive effect of dietary fat. The promotive effect of dietary fat may be mediated by bile acids and fatty acids in colon which induce hyperproliferation of the colonic epithelium. Colonic hyperproliferation is generally considered as a biomarker of an increased susceptibility to colon cancer. The mechanism by which the surface-active bile acids and fatty acids induce hyperproliferation consists probably of damage of the cell-membrane resulting in cytolysis and cell-death. Luminal binding of these surfactants by insoluble calcium phosphate may decrease the solubility of these surfactants, their cytotoxic effects and the induction of hyperproliferation (Figure 1).The experimental studies described in this thesis investigated this hypothesized mechanism by which dietary calcium inhibits proliferation of the colonic epithelium and the risk of colon cancer using the following step-wise approach. First, in in vitro studies (chapter 3) it was shown that bile acids and fatty acids are toxic for erythrocytes and for colonic epithelial cells in vitro (CaCo-2 cells). Moreover, cytotoxicity of these surfactants was similar in both cell-types. Fatty acids were as cytotoxic as bile acids with a similar dependency on hydrophobicity, but in contrast to bile acids, cytotoxicity of fatty acids was apparently not associated with micelle-formation. Low submicellar, sublytic concentrations of bile acids synergistically stimulated fatty acid-induced cytotoxicity. Cytotoxicity of these mixtures of bile acids and fatty acids was, analogous to cytotoxicity of bile acids alone, dependent on micelle formation. The synergistic effect of bile acids on fatty acid-induced cytotoxicity was stimulated by an increasing hydrophobicity of the bile acids. Lowering of the fatty acid concentration of these mixtures drastically decreased their cytotoxic effects. This in vitro study showed that physiologically relevant mixtures of bile acids and fatty acids are toxic to enterocytes as well as erythrocytes.Secondly, it was investigated in rats whether a diet-induced increase in colonic bile acids stimulated cytotoxicity of fecal water and colonic proliferation (chapter 4). Therefore, fecal water was isolated from feces. Fecal water is that fraction of feces which contains the soluble surfactants which are assumed to damage cells. A dietinduced increase in colonic bile acids drastically stimulated cytotoxicity of fecal water analogous to the increase in concentration of bile acids in fecal water. Also an increase in colonic proliferation measured as [ 3H]-incorporation into DNA was observed. Cytotoxicity of fecal water and colonic proliferation were highly correlated (r=0.85, n=24, P4 stimulated the intestinal formation of insoluble CaP i , decreased the concentrations of soluble surfactants and lowered cytotoxicity of fecal water, was investigated (chapter 5). Supplemental CaHPO 4 resulted in a dosedependent decrease in bile acid concentration of fecal water and an increased precipitated fraction of bile acids. Consequently a drastic, dose-dependent fall in cytotoxicity was observed. Correlations between precipitated bile acids and cytotoxicity with precipitated calcium and inorganic phosphate (r>0.90) showed that theseparameters were closely associated. Thus, dietary supplementation with CaHPO 4 decreased cytotoxicity of fecal water by intestinal precipitation of bile acids.Because bile acids and fatty acids are products of fat digestion, the type of dietary fat may influence the cytotoxic effects of the intestinal contents and the interaction with calcium phosphate. Therefore, three different purified types of dietary fat (milk fat, palm oil and corn oil) were used each at a low (25 μmol CaHPO 4 /g diet) and a high (225 μmol CaHPO 4 /g diet) level (chapter 6). Milk fat contains rather large amounts of short- and medium-chain triglycerides (C 4:0 -C 12:0 ), palm oil contains triglycerides rich in palmitate (Ca 16:0 ) and oleate (C 18:1 ) and corn oil contains linoleate (C 18:2 ) rich triglycerides. The excretion of fatty acids was dependent on the type of dietary fat and increased in the order corn oil 4 drastically stimulated fatty acid excretion with the same fat-type dependency. In contrast, concentrations of soluble fatty acids and bile acids were drastically decreased by supplemental CaHPO 4 . This effect was dependent on the type of dietary fat with palm oil resulting in the highest concentration of fatty acids. Cytotoxicity of fecal water decreased analogous to the decrease in concentrations of soluble surfactants with the same fat-type dependency. Multiple regression analysis showed that the concentrations of soluble bile acids and fatty acids are equally important determinants of cytotoxicity and explain 80% (R = 0.89) of the cytotoxicity of fecal water. Intestinal alkaline phosphatase activity in fecal water as a marker of intestinal epitheliolysis showed that the effects on cytotoxicity of fecal water were reflected in effects on intestinal epitheliolysis (r=0.92, PTo investigate whether the luminal effects of dietary calcium resulted in a change in response of the colonic epithelium, the anti-proliferative effect of calcium was studied in rats fed Western-type high risk diets containing low CaHPO 4 (25 μmol Ca/g), low fibre and high fat (40 en-%) levels (chapter 7). It should be noted that this low calcium diet mimicked a human diet with a calcium consumption of 500 mg/day (mean intake in The Netherlands is about 1000 mg/day). Types of fat used were commercially available fats: butter, mimicking a diet with a high saturated mediumchain triglycerides content, saturated margarine, reflecting a diet with a high long-chain saturated fat content, and polyunsaturated margarine, ressembling a diet with a high polyunsaturated fat content. Diets were also supplemented with CaHP0 4 to 225 μmol/g diet. Dietary calcium phosphate decreased soluble surfactant concentrations and cytotoxicity of fecal water. These luminal effects of dietary calcium resulted in a lower intestinal epitheliolysis. On the butter and saturated margarine diets, these protective effects of calcium resulted in a decreased colonic proliferation. On the polyunsaturated diet, proliferation was not decreased by supplemental calcium which may suggest an additional mechanism in the induction of hyperproliferation. Multiple regression analysis of soluble surfactants with cytotoxicity, epitheliolysis and colonic proliferation showed highly significant associations. Cytotoxicity and epitheliolysis as well as epitheliolysis and colonic proliferation were highly correlated (resp. r=0.97 and r=0.88) for control and Ca-supplemented groups. This is consistent with the proposed mechanism and may indicate cause-and-effect relationships. Thus the anti-proliferative effect of dietary calcium is mediated by luminal surfactants and dependent on the type of dietary fat.Finally, the luminal effects of supplemental dietary calcium were studied in a pilot intervention trial with young healthy volunteers. In this study supplemental calcium complexated with phosphate to insoluble calcium phosphate, but in contrast to the animal studies the (already low) concentration of soluble bile acids was not further decreased. The free fatty acid concentration in fecal water was lowered by supplemental calcium. Gaschromatographic analysis of fecal water showed that the composition of the bile acids in fecal water was altered from hydrophobic to hydrophilic. The overall effect of dietary calcium supplementation was a decrease in hydrophobicity of fecal water measured as a decrease in free fatty acid concentration, hydrophobic bile acids and neutral sterols. This resulted in a significant decrease in cytotoxicity of fecal water in these healthy volunteers. Thus, luminal effects of dietary calcium supplementation in humans are analogous to the effects in rats. These effects may offer a molecular explanation of the protective effects of dietary calcium supplementation on colonic epithelial proliferation in patients at risk for colon cancer.CONCLUDING REMARKSThe experimental studies described in this thesis lead to the following conclusions:1. Bile acids and fatty acids are cytotoxic surfactants which cause damage of cellular membranes resulting in cell-death. Lysis of erythrocytes is a convenient and relevant model system to determine cytotoxicity of these surfactants (chapter 3).2. Diet may modulate the proliferative behavior of the colonic epithelium by luminal effects. Cytotoxicity of fecal water measured as lysis of erythrocytes providesrelevant information about the luminal effects of diet (chapter 4 & 5).3. The type of dietary fat influences the concentrations of luminal surfactants, cytotoxicity, intestinal epitheliolysis (chapter 6 & 7) and colonic proliferation (chapter 7). Dietary calcium phosphate supplementation causes precipitation of luminal surfactants. As a consequence, concentrations of soluble cytotoxic surfactants are lowered, which results in a decreased cytotoxicity of fecal water (chapter 5-7). These luminal effects of dietary calcium phosphate decrease intestinal epitheliolysis (chapter 6 & 7) and lower colonic epithelial proliferation (chapter 7).4. In humans, supplemental calcium lowers the hydrophobicity of fecal water and consequently decreases cytotoxicity of fecal water.With regard to these conclusions some remarks have to be made concerning the protective effects of calcium. It should be stressed that cytotoxicity is not a measure of intestinal cell-damage. Luminal cytotoxicity only refers to the potency of the intestinal contents to damage cells. Cytotoxicity is therefore solely determined by the physicochemical characteristics of the luminal surfactants. Lysis of epithelial cells is dependent on this cytotoxicity, but also on the susceptibility of the plasmamembrane to the luminal surfactants. Determinants of this epithelial susceptibility are at present largely unknown. In rats consuming identical diets only differing in the amount of CaHPO 4 and type of dietary fat, the proposed sequence of effects (figure 1) has been demonstrated. However, in the experiment with human volunteers only the luminal effects of dietary calcium supplementation were studied (chapter 8). Whether the observed protective effects result, analogous to the effects in rats, in alower colonic proliferation is at present unknown. Therefore, the results of chapter 8 should only be interpreted as a first indication how dietary calcium in humans could decrease the risk of colon cancer.Further investigations regarding calcium and colon cancer should focuss on the effects of calcium supplementation on colonic epithelial proliferation using a combined biochemical and physiological design. Only these combined efforts may shed some light on the complex role of diet in colorectal carcinogenesis. Many questions have still to be answered. Dose-response and time-relationships need to be ascertained. Whether an optimal dose of calcium supplementation exists, is not clear. Whether dairy products, which are rich in calcium, have the same effects should also be ascertained. Possible interactions not only influenced by the the type of dietary fat, but also interactions between the protective agents fibre and calcium in the intestinal lumen may be important. It should be clear that luminal colonic effects of diet are very complex to study, because of intestinal interactions between the different dietary components. However, these interactions are important in the dietary prevention of colon cancer.In conclusion, the experiments described in this thesis show that dietary supplementation with CaHPO 4 decreases cytotoxicity of fecal water resulting in a decreased colonic epithelial proliferation. The relative importance of dietary calcium as an anti-promoter of colon carcinogenesis has to be established in the following years. Several multi-center intervention trials have started during the last few years studying the effects of calcium supplementation on proliferation-markers and recurrence of polyps. However, one should be cautious not to neglect biochemical and animal studies to investigate mechanisms how calcium could affect the risk of colon cancer. Dietary advice with regard to calcium-intake and the prevention of colon cancer has to await knowledge of relevant mechanisms combined with consistent results in in vitro studies, experiments with animals and human intervention trials