The fit of gold-alloy full-crown castings made with ceramic casting ring liners.

Measurements were made of the fit of gold-alloy full-crown castings produced with dry ceramic ring liners. When used with vacuum investing, these liners absorb relatively large amounts of water from the investment mix (thereby reducing its original W/P ratio) and then function as wet liners, thus increasing the investment's potential expansion and giving castings which are consistently larger than when air investing is used. With four of the five liners tested, investing in air produced many castings which were unacceptably undersized (inaccuracy worse than -0.2%). The fifth liner, an industrial material 2 mm thick, gave only one casting out of 12 which was outside this limit, although all castings were undersized to a lesser extent. Vacuum investing gave improved casting accuracy; with four of the five liners, the improvement was highly significant (p < 0.001), and with the fifth, probably significant (p < 0.05). Even with vacuum investing, however, with only two of the liners did all castings show inaccuracies within +/- 0.2%. With the other three liners, some castings (ranging from 2/10 to 7/9) had inaccuracies worse than -0.2%. With both air and vacuum investing, changing from one liner to another caused changes in relative casting accuracy which were often significant (p < 0.01) or highly significant (p < 0.001). In casting techniques where a ceramic ring liner is used, the choice of specific lining material and the choice between investing in air or under vacuum are important factors which can have a major effect on the fit of castings.     

Impact testing of a polysulphone denture base polymer

A bstract — The impact resistance of a polysulphone denture base polymer has been determined, and for comparison the impact resistance was also determined of a linear poly(methyl methacrylate) and four rubber-modified methacrylate denture base polymers. When tested under mouth conditions the polysulphone had an impact resistance more than four times as high as the poly(methyl methacrylate) and about twice as high as the most impact resistant rubber-modified methacrylate. Unlike some of the other materials tested, the polysulphone did not suffer a reduction in impact resistance on extended ageing under mouth conditions.     

Changes in Experiences With Discrimination Across Pregnancy and Postpartum: Age Differences and Consequences for Mental Health

Objectives. We aimed to contribute to growing research and theory suggesting the importance of examining patterns of change over time and critical life periods to fully understand the effects of discrimination on health, with a focus on the period of pregnancy and postpartum and mental health outcomes.Methods. We used hierarchical linear modeling to examine changes across pregnancy and postpartum in everyday discrimination and the resulting consequences for mental health among predominantly Black and Latina, socioeconomically disadvantaged young women who were receiving prenatal care in New York City.Results. Patterns of change in experiences with discrimination varied according to age. Among the youngest participants, discrimination increased from the second to third trimesters and then decreased to lower than the baseline level by 1 year postpartum; among the oldest participants, discrimination decreased from the second trimester to 6 months postpartum and then returned to the baseline level by 1 year postpartum. Within-subjects changes in discrimination over time predicted changes in depressive and anxiety symptoms at subsequent points. Discrimination more strongly predicted anxiety symptoms among participants reporting food insecurity.Conclusions. Our results support a life course approach to understanding the impact of experiences with discrimination on health and when to intervene.A large and ever-growing body of research has shown that experiences with discrimination are associated with a wide range of adverse mental and physical health outcomes and may help explain socioeconomic and racial/ethnic health disparities in the United States.1,2 Although the majority of this research has been cross-sectional, an increasing number of longitudinal studies have shown that discrimination predicts poorer health.3,4 Some studies have gone further to examine within-person changes over time in discrimination and the resulting health implications.5–7Recently, Gee et al.8 proposed a life course perspective, calling for more research on changes in experiences with discrimination during critical periods to fully understand discrimination’s health effects and inform interventions. We examined changes across pregnancy and 1 year postpartum in experiences with everyday discrimination and consequences in terms of subsequent changes in depressive and anxiety symptoms among predominantly Black and Latina, socioeconomically disadvantaged young women residing in New York City. In their recent theoretical article, Gee et al. asserted:

Exposure to racism can change in nature, importance, and intensity. Similarly, health and the factors that produce health can change. A growing body of research shows that health is not merely the result of risks that occur sporadically at one point in time. Failure to attend to these temporal changes not only shortchanges our knowledge base, but also can lead to missed opportunities for intervention.8^(p967)

Cross-sectional (or even longitudinal) studies examining between-subjects associations of discrimination with health outcomes cannot assess changes in discrimination over time. To advance understanding of the health effects of discrimination, taking a life course perspective and examining changes in discrimination over time are crucial. Gee et al.8 highlighted potential age-patterned exposures to discrimination, with certain critical periods during which changes are more drastic. Some research supports this perspective, with evidence that racial discrimination increases across adolescence5 among African American youths and increases over time6 among African American, Latino, and Asian American youths. Although Gee et al. focused on racism, we suggest that their framework applies to all forms of discrimination.Pregnancy and postpartum may be a critical period to study changes in discrimination, given that women’s experiences with discrimination during pregnancy increase their likelihood of adverse maternal and infant health outcomes such as having a low birth weight infant9,10 and contracting a sexually transmitted infection.11 Also, women experience changes in their bodies, social relationships, and emotions12 during pregnancy and postpartum and come into contact with a variety of new social institutions, including those related to obstetrics and child care; thus, as a result of these life changes, women may experience changes in exposure to discrimination during this time period.8Changes in experiences with discrimination may also vary according to factors such as age, race/ethnicity, nativity, and socioeconomic status. Socioeconomically disadvantaged women, women of color, and women born outside of the United States who may have experienced discrimination regularly throughout their lives might feel that they are treated better or face less discrimination during pregnancy and the postpartum period, when people may extend them courtesies (e.g., giving up a seat on a bus) and institutions may offer added support (e.g., ensuring prenatal and infant care).By contrast, some theories suggest that Black and Latina women in the United States may experience heightened discrimination during pregnancy and postpartum because of group stereotypes related to sexuality and motherhood (e.g., sexual promiscuity, single parenthood) and the societal devaluation of motherhood in women of color.13,14 Some of these negative stereotypes specifically target Black and Latina adolescents and young women14 and so may be particularly relevant for younger age groups. Thus, experiences with discrimination can increase or decrease during pregnancy and postpartum, and the pattern of change may vary on the basis of characteristics such as age, race/ethnicity, nativity, and socioeconomic status. It is therefore important to assess these characteristics as potential moderators of changes in discrimination during this period.Discrimination is an important determinant of mental health across different social groups.1,2 The majority of research on discrimination and mental health is cross sectional; as noted, however, an increasing amount of research has explored this association longitudinally. For example, individual differences in Black Americans’ experiences with racial discrimination have been found to predict depressive and anxiety symptoms at a later time point, but differences in depressive and anxiety symptoms have not been found to predict racial discrimination at a later point.4,15Studies have begun to explore whether experiences with discrimination change over time and whether these changes are associated with changes in mental health. Schulz et al.7 found that changes over 2 time points (spaced 5 years apart) in Black American women’s experiences with discrimination were positively associated with simultaneous changes in depressive symptoms and negatively associated with changes in self-rated health.Greene et al.6 found that changes in experiences with discrimination across 5 time points (over 3 years) were negatively associated with simultaneous changes in self-esteem and positively associated with changes in depressive symptoms among Black, Latino, and Asian American high school students. Similarly, Brody et al.5 found that changes in experiences with racial discrimination across 3 time points (over 5 years) were positively associated with simultaneous changes in conduct problems and depressive symptoms among Black adolescents. To the best of our knowledge, despite this existing research on discrimination and depressive symptoms, no work has examined associations between changes in discrimination and changes in anxiety or assessed these associations during pregnancy.Yet, pregnancy and postpartum may be a particularly important period during which to examine associations of discrimination with depressive and anxiety symptoms. During pregnancy, these symptoms have adverse consequences for birth outcomes (e.g., preterm birth and low birth weight) and infant development (e.g., cognitive and motor development).16 In the postpartum period, these symptoms have adverse consequences with respect to parenting behaviors (e.g., playing with and talking to the infant) and the health of both the mother and the child.17 In addition, although past research suggests that discrimination has adverse mental health consequences across diverse groups, much of this research has focused on specific groups (e.g., Black Americans), and thus it is important to examine whether these associations vary according to factors such as age, race/ethnicity, nativity, and socioeconomic status.The first aim of our study was to examine changes in experiences with discrimination across pregnancy and 1 year postpartum and assess whether age, race/ethnicity, nativity, or socioeconomic status moderated the pattern of change. Our second aim was to explore whether changes in experiences with discrimination over time predicted changes in depressive and anxiety symptoms at subsequent points and whether the sociodemographic factors just described moderated these associations.Given the competing theories described earlier, we did not have a specific expected pattern of change; rather, we hypothesized that experiences with discrimination would change across pregnancy and the postpartum period and that age, race/ethnicity, nativity, or socioeconomic status of participant might moderate that pattern. Also, consistent with past work showing associations between discrimination and mental health across diverse groups, we hypothesized that changes in experiences with discrimination across pregnancy and postpartum would significantly positively predict changes in depressive and anxiety symptoms at subsequent time points and that participants’ age, race/ethnicity, nativity, and socioeconomic status would not moderate those associations.     

A Closer Look at Racism and Heterosexism in Medical Students’ Clinical Decision-Making Related to HIV Pre-Exposure Prophylaxis (PrEP): Implications for PrEP Education

Social biases among healthcare providers could limit PrEP access. In this survey study of 115 US medical students, we examined associations between biases (racism and heterosexism) and PrEP clinical decision-making and explored prior PrEP education as a potential buffer. After viewing a vignette about a PrEP-seeking MSM patient, participants reported anticipated patient behavior (condomless sex, extra-relational sex, and adherence), intention to prescribe PrEP to the patient, biases, and background characteristics. Minimal evidence for racism affecting clinical decision-making emerged. In unadjusted analyses, heterosexism indirectly affected prescribing intention via all anticipated behaviors, tested as parallel mediators. Participants expressing greater heterosexism more strongly anticipated increased risk behavior and adherence problems, which were associated with lower prescribing intention. The indirect effect via condomless sex remained significant adjusting for background characteristics. Prior PrEP education did not buffer any indirect effects. Heterosexism may compromise PrEP provision to MSM and should be addressed in PrEP-related medical education.     

Mechanisms of checkpoint inhibition-induced adverse events

Immune checkpoint inhibition has revolutionized the treatment of several solid cancers, most notably melanoma and non-small-cell lung cancer (NSCLC). Drugs targeting cytotoxic T lymphocyte antigen (CTLA)-4 and programmed cell death 1 (PD-1) have made their way into routine clinical use; however, this has not been without difficulties. Stimulation of the immune system to target cancer has been found to result in a reduction of self-tolerance, leading to the development of adverse effects that resemble autoimmunity. These adverse effects are erratic in their onset and severity and can theoretically affect any organ type. Several mechanisms for immune-related toxicity have been investigated over recent years; however, no consensus on the cause or prediction of toxicity has been reached. This review seeks to examine reported evidence for possible mechanisms of toxicity, methods for prediction of those at risk and a discussion of future prospects within the field.     

Differential expression of DNA topoisomerases I and II during the eukaryotic cell cycle.

We have utilized antibody probes to examine the expression of DNA topoisomerases I and II and chromosome scaffold protein Sc-2 in normal and transformed cells. Neither topoisomerase I nor Sc-2 shows significant fluctuations in content or stability across the cell cycle. In contrast, topoisomerase II undergoes significant cell cycle-dependent alterations in both amount and stability. As cells progress from mitosis into G1, much of the topoisomerase II is degraded. During the first 2 hr of G1, the half life of topoisomerase II is decreased from that measured in asynchronous cell populations by a factor of 7. This suggests that the chromosome condensation/decondensation cycle is coupled to a parallel cycle of synthesis and degradation of topoisomerase II. In control experiments, we also found that the half-life of topoisomerase II is shorter in normal cells than in transformed cells by a factor of 4. Since the number of copies of topoisomerase II per cell is also lower in normal cells, this suggests that control of topoisomerase II stability is altered upon transformation. The stability of topoisomerase I and Sc-2 does not differ significantly between normal and transformed cells.