Anti-angiogenic effects of the tubulysin precursor pretubulysin and of simplified pretubulysin derivatives

BACKGROUND AND PURPOSE

The use of tubulin-binding compounds, which act in part by inhibiting tumour angiogenesis, has become an integral strategy of tumour therapy. Recently, tubulysins were identified as a novel class of natural compounds of myxobacterial origin, which inhibit tubulin polymerization. As these compounds are structurally highly complex, the search for simplified precursors [e.g. pretubulysin (Prt)] and their derivatives is mandatory to overcome supply problems hampering clinical development. We tested the anti-angiogenic efficacy of Prt and seven of its derivatives in comparison to tubulysin A (TubA).

EXPERIMENTAL APPROACH

The compounds were tested in cellular angiogenesis assays (proliferation, cytotoxicity, cell cycle, migration, chemotaxis, tube formation) and in vitro (tubulin polymerization). The efficacy of Prt was also tested in vivo in a murine subcutaneous tumour model induced with HUH7 cells; tumour size and vascularization were measured.

KEY RESULTS

The anti-angiogenic potency of all the compounds tested ran parallel to their inhibition of tubulin polymerization in vitro. Prt showed nearly the same efficacy as TubA (EC₅₀ in low nanomolar range in all cellular assays). Some modifications in the Prt molecule caused only a moderate drop in potency, while others resulted in a dramatic loss of action, providing initial insight into structure–activity relations. In vivo, Prt completely prevented tumour growth and reduced vascular density to 30%.

CONCLUSIONS AND IMPLICATIONS

Prt, a chemically accessible precursor of some tubulysins is a highly attractive anti-angiogenic compound both in vitro and in vivo. Even more simplified derivatives of this compound still retain high anti-angiogenic efficacy.     

Associations of Adolescent Hopelessness and Self-Worth With Pregnancy Attempts and Pregnancy Desire

Objectives. We examined the associations of pregnancy desire (ambivalence or happiness about a pregnancy in the next year) and recent pregnancy attempts with hopelessness and self-worth among low-income adolescents.Methods. To evaluate independent associations among the study variables, we conducted gender-stratified multivariable logistic regression analyses with data derived from 2285 sexually experienced 9- to 18-year-old participants in the Mobile Youth Survey between 2006 and 2009.Results. Fifty-seven percent of youths reported a desire for pregnancy and 9% reported pregnancy attempts. In multivariable analyses, hopelessness was positively associated and self-worth was negatively associated with pregnancy attempts among both female and male youths. Hopelessness was weakly associated (P = .05) with pregnancy desire among female youths.Conclusions. The negative association of self-worth and the positive association of hopelessness with pregnancy attempts among young men as well as young women and the association of hopelessness with pregnancy desire among young women raise questions about why pregnancy is apparently valued by youths who rate their social and cognitive competence as low and who live in an environment with few options for material success.Rates of adolescent pregnancy and childbearing in the United States are among the highest in the developed world.1 Each year, approximately 750 000 women younger than 20 years become pregnant,2 and about 400 000 give birth.3 In the United States, adolescent pregnancy rates are about two thirds higher among non-White young women than among White young women, and childbearing rates are approximately one third higher2; 57% of births to adolescents in 2010 were to African American or Hispanic/Latino mothers.3 Surveillance data for 9th- to 12th-grade US students show that Blacks and Hispanics are more likely than Whites to engage in risk behaviors associated with pregnancy (e.g., vaginal intercourse at an early age, nonuse of hormonal contraceptives).4Race and ethnicity do not, in themselves, explain adolescent pregnancy risk. Kirby identified more than 100 antecedents of adolescent pregnancy, primarily related to the types of physical and social environments in which minority youths in the United States are disproportionately represented.5 He concluded that most risk factors, including poor school performance6 and residence in a socioeconomically disadvantaged neighborhood,7–9 reflected dysfunction, disadvantage, or disorganization. Offspring of adolescent parents or sisters of women who began childbearing in adolescence are at high risk for adolescent parenthood, suggesting a cultural or intergenerational component.8–10 Family quality, especially parent characteristics and relationships9,11–16; the quality of relationships with one’s school, residential community, and peers6,7,9,12,14; and substance use and mental health,9,17–22 are associated with pregnancy or pregnancy risk behaviors among both female and male adolescents.Youths who live in challenging social and physical environments typically have negative psychological and cognitive responses to their surroundings (e.g., low self-worth and hopelessness).23,24 Although the evidence is mixed,20–22,25,26 it is generally assumed that poor self-image, poor self-worth, and poor self-esteem in girls are associated with pregnancy or pregnancy risk markers, including early age at first vaginal intercourse and an inability to negotiate condom use. Hopelessness reflects negative expectations about future desired or valued outcomes and helplessness with respect to one’s ability to change the odds that negative outcomes will occur.27 Hopelessness has been identified as a risk marker for youth violence and self-harm and poor adult social trajectories.24,28–31 In industrialized countries, adolescent pregnancy (and the decision to continue a pregnancy) may be a consequence of a lack of hope and the perception of too few positive life options,32,33 although only a limited number of studies have directly examined hopelessness and pregnancy risk.Kogan et al. examined a related phenomenon, conventional future orientation, and found associations with decreased sexual risk taking at age 16 and avoidance of pregnancy at age 19 years.34 A 2013 study of Mobile Youth Survey (MYS) participants showed that having a positive feeling about the future was marginally associated with older age at first intercourse, a risk factor for adolescent pregnancy.35 Neither study examined female and male youths separately. Despite the health, social, and economic burdens associated with pregnancy involvement among boys,9,36,37 little is known about the psychological or cognitive correlates of adolescent paternity risk.Adolescent pregnancy and childbearing disproportionately occur among historically marginalized youths and present significant, and often lifelong, social and health risks to parents and their offspring.37 Many known antecedents, including poverty, neighborhood quality, and quality of the parental relationship, may be intractable. However, learned cognitive factors such as hopelessness and low self-worth may be modifiable.27Because of our overarching interest in identifying potentially intervenable correlates of pregnancy involvement among high-risk youths, we examined the hypotheses that hopelessness is positively associated and self-worth is negatively associated with 2 known risk markers of adolescent pregnancy: pregnancy attempts and pregnancy desire.15,26,38–42 Our analyses involved a cross-sectional sample of adolescent female and male participants in the MYS,43 a study of primarily African American and impoverished young people with little variation in their social risk for pregnancy. Because there may be gendered cultural meanings or consequences associated with early pregnancy and parenting (especially in communities where rates of adolescent pregnancy are disproportionately high) and because the psychological or cognitive correlates of pregnancy risk may vary according to gender,21,22 we examined female and male youths separately.     

Response from lieberman and colleagues

Respond on comments on Lieberman's article: Cyclosiloxanes Produce Fatal Liver and Lung Damage in Mice. Environ Health Perspect 107:161-165     

Associations of weight loss and changes in fat distribution with the remission of hypertension in a bi-ethnic cohort: the Atherosclerosis Risk in Communities Study

BACKGROUND: To examine associations of weight loss and changes in fat distribution with changes in blood pressure and the remission of hypertension in a community-based sample. METHODS: Participants were 3245 white and African-American men and women, 45-64 years of age, who participated in the Atherosclerosis Risk in Communities Study over an average of 9 years. Mixed models analyses were used to examine the associations of weight loss and changes in fat distribution with changes in blood pressure. Proportional hazard models with time-dependent covariates were used to examine the associations of weight loss and changes in fat distribution with the remission of hypertension. RESULTS: Weight loss was associated with a decrease in systolic blood pressure and diastolic blood pressure and with an increased rate of remission of hypertension. Hazard ratios of the remission of hypertension associated with 1-kg increment in annual weight loss were 2.04 (95% confidence interval [CI]: 1.62-2.59), 1.38 (95% CI: 1.14-1.67), 1.84 (95% CI: 1.47-2.29), and 1.53 (95% CI: 1.14-2.05) for white women, African-American women, white men, and African-American men, respectively. Changes in fat distribution were associated with the remission of hypertension in younger (45-54 years) participants. CONCLUSIONS: Weight loss was associated with a decrease in blood pressure and with remission of hypertension in white and African-American men and women.     

Expenditures in caring for patients with dementia who live at home.

OBJECTIVES. Given the national interest in progressive dementia, we estimated expenditures incurred in caring for dementia patients who live at home. METHODS. Primary caregivers of 264 patients from a university-based memory disorders clinic were interviewed at baseline and asked to keep service use diaries for 6 months; 141 caregivers who returned the diaries are the focus of this report. We examined both formal and informal services (distinguished by whether money was exchanged) and associated expenditures. RESULTS. Neither caregivers returning diaries nor their patients differed at baseline from those not returning diaries and their patients. Expenditures incurred over 6 months were extensive for both formal ($6986) and informal ($786) services. Out-of-pocket expenditures were high (e.g., in-home companion or sitter, adult day care, visiting nurse). Multivariable analyses indicated that patients with more severe symptoms of dementia and families with higher incomes reported significantly higher expenditures. CONCLUSIONS. The expense of caring for patients with progressive dementia living at home may be higher than previously estimated and frequently involves expenses paid directly by patients and their families.     

Qualitative and quantitative detection of human pathogenic Yersinia enterocolitica in different food matrices at retail level in Bavaria

Yersinia enterocolitica is a major foodborne pathogen and the third most important bacteriological cause of diarrhea in Germany. However, studies investigating the occurrence of human pathogenic Y. enterocolitica in food at the retail level are very rare. Most of the studies published so far show qualitative but not quantitative data concerning the prevalence of this human pathogen. In this study the qualitative and quantitative assessment of human pathogenic Y. enterocolitica in different food matrices was investigated. For the qualitative analysis we used an enrichment method according to the International Organisation of Standardization (ISO) standard in combination with a real-time polymerase chain reaction (PCR) method detecting the ail gene of Y. enterocolitica. After detecting Y. enterocolitica in a sample, a quantitative investigation on Cefsulodin-Irgasan-Novobiocin (CIN) Agar was done to get information about the contamination level of the different samples. During the years 2008 and 2009, 446 samples of pork and pork products, 51 samples of game meat, and 61 raw milk samples were investigated for the presence of human pathogenic Y. enterocolitica. The samples were collected at the retail level in Bavaria. From the pork samples investigated, 81 samples (18%) were positive for the ail gene by real-time PCR, but human pathogenic Y. enterocolitica O:3 were found only in 46 (10%) pork samples by culture; the concentration in the samples ranged between 0.04 cfu/g and 2.30?×?10(5) cfu/g. Three game meat samples were positive by real-time PCR, but not by the cultural detection. All raw milk samples were negative by real-time PCR and culture.     

Abdominal obesity and coronary artery calcification in young adults: the Coronary Artery Risk Development in Young Adults (CARDIA) Study

BACKGROUND: Whether abdominal obesity is related to coronary artery calcification (CAC) is not known. OBJECTIVE: We investigated the relations of waist girth and waist-hip ratio (WHR) to CAC in 2951 African American and white young adults from the Coronary Artery Risk Development in Young Adults Study. DESIGN: The present study was a cross-sectional and observational cohort study. Using standardized protocols, we measured CAC in 2001-2002 by using computed tomography and measured waist and hip girths in 1985-1986 (baseline), 1995-1996 (year 10), and 2001-2002 (year 15, waist girth only). CAC was classified as present or absent, whereas waist girth and WHR were placed in sex-specific tertiles. RESULTS: After adjustment for age, sex, race, clinical center, physical activity, cigarette smoking, education, and alcohol intake, baseline waist girth and WHR were directly associated with a higher prevalence of CAC 15 y later (P for trend < 0.001 for both). The odds ratios (ORs) for CAC in the highest versus lowest tertiles of waist girth and WHR were 1.9 (95% CI: 1.36, 2.65) and 1.7 (1.23, 2.41), respectively. Waist girth and WHR at year 10 and waist girth at year 15 similarly predicted CAC. These associations persisted after additional adjustment for systolic blood pressure, fasting insulin concentrations, diabetes, and antihypertensive medication use but became nonsignificant after additional adjustment for blood lipids. CONCLUSIONS: Abdominal obesity measured by waist girth or WHR is associated with early atherosclerosis as measured by the presence of CAC in African American and white young adults. This is consistent with an involvement of visceral fat in the occurrence of coronary artery calcium in young adults.     

An improved cost-effective, reproducible method for evaluation of bone loss in a rodent model

Aim: This study was designed to investigate the utility of two "new" definitions for assessment of bone loss in a rodent model of periodontitis.
Material and Methods: Eighteen rats were divided into three groups. Group 1 was infected by Aggregatibacter actinomycetemcomitans (Aa), group 2 was infected with an Aa leukotoxin knock-out, and group 3 received no Aa (controls). Microbial sampling and antibody titres were determined. Initially, two examiners measured the distance from the cemento-enamel-junction to alveolar bone crest using the three following methods; (1) total area of bone loss by radiograph, (2) linear bone loss by radiograph, (3) a direct visual measurement (DVM) of horizontal bone loss. Two "new" definitions were adopted; (1) any site in infected animals showing bone loss >2 standard deviations above the mean seen at that site in control animals was recorded as bone loss, (2) any animal with two or more sites in any quadrant affected by bone loss was considered as diseased.
Results: Using the "new" definitions both evaluators independently found that infected animals had significantly more disease than controls (DVM system; p <0.05).
Conclusions: The DVM method provides a simple, cost effective, and reproducible method for studying periodontal disease in rodents.     

Purpura

Purpura is a cutaneous manifestation of a wide variety of diseases. These include such diverse entities as platelet defects, vasculitides, and disorders of connective tissue. Uncovering the underlying disorder in a patient with purpura is a stimulating challenge to the clinician's diagnostic abilities.