Individual differences in frequency and impact of daily memory lapses: results from a national lifespan sample

BACKGROUND

Everyday memory problems are believed to increase with age, leading many researchers to focus on older ages when examining reports of memory lapses. However, real world memory lapses are ubiquitous across the adult lifespan, though less is known about the types of problems and their impacts at younger ages. The current study examined occurrence and impacts of memory lapses using daily diaries in a broad age range and whether characteristics of lapses varied across age, gender, or education level.

METHODS

Using an 8-day daily diary protocol, 2,018 individuals (ages 25-91) provided reports of their experiences of two types of daily memory lapses (retrospective and prospective) as well as the impact those lapses had on their emotional and functional well-being that day. Using multilevel modeling, we examined the likelihood of reporting memory lapses and their impacts on daily life and whether these depended on age, gender, or education level.

RESULTS

Participants reported lapses on approximately 40% of days; retrospective memory lapses were significantly more likely than prospective lapses. Older ages and higher education level were related to greater likelihood of reporting retrospective lapses. Women (compared to men) were more likely to report prospective memory lapses. Women also tended to report greater impacts of their memory lapses. Lower education levels were related to greater impacts of memory lapses compared to higher education levels. Interestingly, age was not related to impacts of lapses.

DISCUSSION

Our results indicate that memory lapses are common across the lifespan and that those individuals more likely to report lapses are not necessarily those that experience the greatest impacts of those lapses on daily life. Additional work is needed to understand the daily experience of memory lapses and how they differentially affect individuals regardless of age, gender, and education.

CONCLUSIONS

Memory lapses are an important aspect of daily life across the lifespan and require measurement in an individual's real-world environments. Better measurement of these experiences will allow the development of more sensitive measures of changes in cognitive functioning that may impact an individual's ability to live independently.

Age Discrepancies Across Two Decades: Desiring to be Younger Is Associated with Daily Negative Affect Over Three Waves of Assessment

Negative perceptions of aging and older adulthood, including the idealization of youth, are common in the United States. Past work has found that holding negative perceptions of aging is closely associated with poor mental and physical health consequences, yet few studies have examined how these perceptions impact day-to-day experiences. The current study had two objectives: (1) investigate whether age discrepancy (specifically desiring to be younger than one's chronological age) was related to daily negative affect and (2) examine whether this relationship changed as participants aged over time. We utilized the Midlife in the United States (MIDUS) diary study, a longitudinal measurement burst study with three waves of 8-day daily diaries indexing approximately 20 years. Participants (N = 2398; Mage [baseline] = 46.85, SD = 12.24; 54.7% women; 92.4% White) reported their desired age as well as daily negative affect at each wave. Using multilevel modeling, we examined whether age discrepancy predicted daily negative affect across 3 waves of observation. Results supported a significant relationship between age discrepancy and daily negative affect. However, no interactions among age discrepancy and baseline age or time across study were found. This suggests that the relationship between age discrepancy and daily negative affect was consistent across waves and participants over a 20-year period and provides evidence for the pernicious effect of deidentifying with one's real age on daily life. Daily experiences can act as potential risk or protective factors and shape developmental trajectories. Reducing ageism through societal interventions or increasing personal acceptance of aging through targeted interventions are two potential pathways of promoting health and well-being across the lifespan.

How Does Exposure to Dementia Relate to Subjective Cognition? A Systematic Review

Background and Objectives

Subjective cognitive decline (SCD) may be indicative of future objective cognitive decline. However, factors other than objective cognitive performance may influence SCD. This review addresses whether family history or close, nonfamilial exposure to dementia is associated with self-reported SCD.

Research Design and Methods

Searches were conducted in PubMed, PsycINFO, Web of Science, and the Dissertations and Theses database. Eligible articles included measures of self-reported cognition for community-dwelling middle-aged or older adults (40+ years) not diagnosed with dementia, and who had either a family history of dementia, a family member, spouse, or close friend with dementia. The quality of evidence was evaluated using the LEGEND Appraisal Tool. Evidence was synthesized narratively.

Results

A total of 32 articles were included, with 28 rated as good quality. Across studies, the relationship between dementia exposure and SCD was inconsistent. A significant association between exposure and SCD was found in 6 studies; however, 17 reviewed studies found no evidence of a relationship. The remaining 9 studies found mixed associations. Modifying factors that could potentially influence these associations were exploratorily identified among studies to provide context to our results. These factors included dementia worry, emotional closeness, and measurement sensitivity.

Discussion and Implications

Findings of this review suggest that both first-degree relatives and spouses of persons with dementia may have an increased likelihood of reporting SCD, although the current heterogeneity in definitions of exposure to dementia and SCD may influence these findings. In addition to the relationship between dementia exposure and SCD, future research should examine potential modifiers, including meaning attributed to exposure, as identifying how these perceptions affect cognition may promote early intervention.

Daily Memory Lapses and Affect: Mediation Effects on Life Satisfaction

Memory lapses are a type of daily challenge that are common to most people and are associated with negative mood outcomes. How daily challenges are associated and linked to broad domains, like life satisfaction and well-being, has been underexamined. Life satisfaction is often assessed from a macro-level that emphasizes average differences over longer timeframes, yet daily experiences (i.e., micro-level) may accumulate to shape these characteristics. In the current study, we examined if daily memory lapses (e.g., difficulties with word-finding or forgetting a meeting) were associated with life satisfaction, and whether this relationship was mediated by the associated changes in positive and negative affect due to daily memory lapses. In a coordinated analysis of two datasets (N = 561, ages 25-93 years), we used multilevel structural equation modeling to assess how daily memory lapses may influence the broader outcome of global life satisfaction. The pattern of results was similar across datasets: memory lapses were associated with reduced positive affect and increased negative affect. Further, the daily affect associated with daily memory lapses significantly mediated the relationship between lapses and life satisfaction, while the direct relationship between memory lapses and life satisfaction was non-significant. This study provides support for the role of daily challenges, specifically memory lapses, influencing broader constructs such as psychological well-being by identifying the key factor of affective responses. Future work should identify other salient daily challenges, as well as explore if reducing the affective response to challenges through targeted interventions would mitigate impacts on distal functioning.

Measuring Memory Lapses and Their Impact on Daily Life: Results From Two Daily Diary Studies

Memory lapses (e.g., forgetting a medication) are common for most people, yet past methods of assessment relied upon retrospective reports from long recall windows. Recently, researchers have incorporated daily diary methods to capture memory lapse frequency closer to the experience in real-world environments. This study describes the utility of the Daily Memory Lapses Checklist using data from two 14-day diary studies (Combined Sample = 467; 66% women). Frequency and impact (i.e., irritation and interference) of prospective and retrospective memory lapses were assessed at both individual- and daily levels. Across studies, memory lapses occurred on more than one-third of assessment days. Retrospective lapses were reported more frequently than prospective; however, both lapses had a similar impact. The Daily Memory Lapses Checklist represents a flexible measure that separates the occurrence of a memory lapse from its impact on daily life: metrics that will enhance our understanding of daily experiences of cognitive functioning.

COVID-19-Related Daily Stress Processes in College-Aged Adults: Examining the Role of Depressive Symptom Severity

Exposure to daily stressors specific to the COVID-19 pandemic (e.g., threat of infection) is associated with emotional distress, heightened stress reactivity, and increased depressive symptomology. Herein, we examined whether current depressive symptomology modulates the association between COVID-19-related daily stressor exposure and negative affective reactivity in young, otherwise healthy, college-aged adults. Fifty-eight adults (21 men; 22±3years) completed a daily web-based interview for eight consecutive days to assess COVID-19-related daily stress exposure and emotional responsiveness (September–November 2020). Depressive symptom severity was assessed using the Patient Health Questionnaire-9 (PHQ-9), and a score of ≥10 (range: 0–27) was used to define adults with a depressive episode (n=20). Participants reported at least one COVID-19-related stressor on 35.8% of interview days. Depressive symptomology did not predict the likelihood of exposure to a COVID-19-related stressor (p=0.46; OR=1.52; 95% CI: 0.492–4.718). However, negative affect (NA) was greater on days with an exposure to any COVID-19-specific daily stressor in adults with moderate-to-severe depressive symptoms (b=0.28, SE=0.093, p=0.003) but not in those without (b=0.009, SE=0.074, p=0.90), such that negative affective reactivity to COVID-19-related stressors was amplified in adults with a current depressive episode (p=0.019). Depressive symptomology did not moderate positive affective reactivity (p=0.686). Taken together, these data suggest that exposure to daily stressors related to COVID-19 further worsens NA in adults with a current depressive episode, potentially rendering them more susceptible to adverse mental health outcomes during the pandemic.

Longitudinal Relationships Between Subjective Cognitive Decline and Objective Memory: Depressive Symptoms Mediate Between-Person Associations

BACKGROUND

Subjective cognitive decline (SCD) may be an early indicator of cognitive impairment, but depressive symptoms can confound this relationship. Associations may be influenced by differences between individuals (i.e., between-persons) or how each individual changes in their experiences over time (i.e., within-persons).

OBJECTIVE

We examined depressive symptoms as a mediator of the between- and within-person associations of SCD and objective memory in older adults.

METHODS

Coordinated analyses were conducted across four datasets drawn from large longitudinal studies. Samples (range: n = 1,889 to n = 15,841) included participants 65 years of age or older with no dementia at baseline. We used multilevel structural equation modeling to examine the mediation of SCD and objective memory through depressive symptoms, as well as direct relationships among SCD, objective memory, and depressive symptoms.

RESULTS

Older adults who were more likely to report SCD had lower objective memory on average (between-person associations), and depressive symptoms partially mediated this relationship in three of four datasets. However, changes in depressive symptoms did not mediate the relationship between reports of SCD and declines in objective memory in three of four datasets (within-person associations).

CONCLUSION

Individual differences in depressive symptoms, and not changes in an individual's depressive symptoms over time, partially explain the link between SCD and objective memory. Older adults with SCD and depressive symptoms may be at greater risk for poor cognitive outcomes. Future research should explore how perceived changes in memory affect other aspects of psychological well-being, and how these relationships influence cognitive decline and Alzheimer's disease risk.

Individual Differences and Features of Self-reported Memory Lapses as Risk Factors for Alzheimer Disease Among Adults Aged 50 Years and Older: Protocol for a Coordinated Analysis Across Two Longitudinal Data Sets

BACKGROUND

Increasing evidence has promoted the clinical utility of self-reported memory problems for detecting early impairment associated with Alzheimer disease (AD). However, previous studies investigating memory problems often conflated the types of problems (ie, retrospective and prospective) with their features (ie, frequency and consequences). This bias limits the specificity of traditional measures of memory problems and minimizes their ability to detect differential trajectories associated with cognitive decline. In this study, we use a novel measure of self-reported memory problems that uses daily reports of memory lapses to disentangle types from features for analyzing the impact of each dimension in two longitudinal data sets. Furthermore, this study explores the individual difference factors of age and gender as potential moderators of the relationships between self-reported memory lapses and objective cognitive decline.

OBJECTIVE

The aim of this study is to describe the protocol for a secondary data analysis project that explores the relationship between experiences of daily memory lapses and their associations with cognitive decline in middle-aged and older adults.

METHODS

This study uses multilevel, coordinated analyses across two measurement burst data sets to examine the links between features and consequences of memory lapses (retrospective and prospective) and their association with objective cognitive decline. This study's sample (N=392; aged 50-85 years; n=254, 64.8% women) is drawn from two ongoing, nationally funded research studies: The Effects of Stress on Cognitive Aging, Physiology, and Emotion study and the Einstein Aging Study. Both studies assess the daily experience of memory lapses, including the type as well as the emotional and functional outcomes, and objective measures of cognition, such as processing speed and episodic memory. We will use multilevel modeling to test our conceptual model demonstrating that differences in frequency and types of memory lapses show differential trends in their relationships with cognitive decline and that these relationships vary by the age and gender of participants.

RESULTS

This project was funded in August 2019. The approval for secondary data analysis was given by the institutional review board in February 2020. Data analysis for this project has not yet started.

CONCLUSIONS

The early and accurate identification of individuals most at risk for cognitive decline is of paramount importance. Previous research exploring self-reported memory problems and AD is promising; however, limitations in measurement may explain previous reports of inconsistences. This study addresses these concerns by examining daily reports of memory lapses, how these vary by age and gender, and their relationship with objective cognitive performance. Overall, this study aims to identify the key features of daily memory lapses and the differential trajectories that best predict cognitive decline to help inform future AD risk screening tools.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/25233.

Holding on to pieces of the past: Daily reports of nostalgia in a life-span sample

Nostalgia, the fond remembrance of one's past, is a common experience hypothesized to increase across the life span. Yet data on the specific features of nostalgia, such as daily frequency and associated affect, are scarce. This study sought to address this limitation by assessing the daily experience of nostalgia using experience-sampling methods. A life-span sample of 108 participants (47 young, 31 middle-aged, and 30 older adults) completed a 2-week, twice-daily experience-sampling study that yielded data describing the frequency and emotions of everyday nostalgia. Multilevel logistic regression analyses supported increased nostalgia frequency at every life stage: Young adults were 60% less likely to report nostalgia compared with middle-aged adults (odds ratio [OR] = .40), whereas older adults were 3 times more likely than middle-aged adults to report nostalgia (OR = 3.05). Additionally, the experience of nostalgia was associated with significant heterogeneity in positive and negative affect. Approximately 72% of participants experienced an increase in positive affect, and 51% experienced an increase in negative affect. For young and middle-aged adults, a change in positive affect was associated with a 2-times-larger increase in nostalgia likelihood, whereas a change in negative affect was more strongly associated with a nostalgia experience in older adults. The current study provides increased evidence for the affectively mixed nature of nostalgia and how the affective pattern differs for adults of different ages. Greater nostalgia frequency may be instrumental during life review when individuals make meaning of their lives, fulfilling developmental goals of late adulthood. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Age Differences in Preferences for Fear-Enhancing Vs. Fear-Reducing News in a Disease Outbreak

Older adults (OA) prefer positive over negative information in a lab setting, compared to young adults (YA; i.e., positivity effects). The extent to which OA avoid negative events or information relevant for their health and safety is not clear. We first investigated age differences in preferences for fear-enhancing vs. fear-reducing news articles during the Ebola Outbreak of 2014. We were able to collect data from 15 YA and 13 OA during this acute health event. Compared to YA, OA were more likely to read the fear-enhancing article, select hand-sanitizer over lip balm, and reported greater fear of Ebola. We further investigated our research question during the COVID-19 pandemic with 164 YA (18-30 years) and 171 OA (60-80 years). Participants responded to an online survey about the COVID-19 pandemic across 13 days during the initial peak of the pandemic in the United States (U.S.). Both YA and OA preferred to read positive over negative news about the coronavirus, but OA were even more likely than YA to prefer the positive news article. No age differences in the fear of contraction were found, but OA engaged in more health-protective behaviors compared to YA. Although OA may not always report greater fear than YA or seek out negative information related to a health concern, they still engage in protective health behaviors. Thus, although positivity effects were observed in attention and emotional reports (in the COVID-19 study), OA still modified their behaviors more than YA (giveaway in both studies, and health-protective behavior change in the COVID-19 study), suggesting that positivity effects did not hamper OA ability to respond to a health crisis.

Ageism and Behavior Change During a Health Pandemic: A Preregistered Study

The COVID-19 pandemic has led to a suspected surge of ageism in America and has imposed critical health and safety behavior modifications for people of all ages (Ayalon et al., 2020; Lichtenstein, 2020). Given that older adults are a high-risk group, maintaining their safety has been paramount in implementing preventive measures (i.e., more handwashing, social distancing); however, making such behavior modifications might be contingent on how one views older adults (i.e., ageist stereotypes). Therefore, the goal of the current pre-registered study was to explore if hostile and benevolent ageism relate to pandemic-related fear and behavior change. An online survey assessing responses to the pandemic was taken by 164 younger and 171 older adults. Higher hostile ageism predicted lower pandemic-related behavior modification. Those high in benevolent ageism reported lower behavior change, but also reported higher pandemic-related fear; however, when pandemic-related fear was considered a mediator between the two, the directionality between benevolent ageism and behavior change switched, indicating a suppression effect. These findings highlight that ageist attitudes do predict responses to the pandemic and that hostile and benevolent ageism are distinct facets that have unique implications during a health pandemic.

"We" Before "Me": Differences in Usage of Collectivistic and Individualistic Language Influence Judgments of Electability and Performance

OBJECTIVES

Older adults are often judged to be warm, but not competent, which contradicts their representation in positions of authority. This study sought to extend evidence of age differences in more individualistic (e.g., "I") and collectivistic (e.g., "we") language and explore their impact on judgments of performance and electability.

METHOD

Speeches from young and older adults who campaigned for a fictitious position were analyzed using Linguistic and Inquiry Word Count Software. Words fitting specified categories (e.g., pronouns, affect) were compared to outcome judgments obtained from trained coders on the dimensions of performance and electability.

RESULTS

Older adults used significantly more "we"-language. Young adults used more "I"-language, and more positive affect, achievement, and power language. Language choices and coder judgments were associated such that the more "I"-language that was used during the speech, the less electable the candidate was judged. This relationship was not found for "we"-language.

DISCUSSION

This study found no evidence for collectivistic language enhancing ratings of electability or performance; however, an age-invariable, negative relationship was obtained between increased individualistic language and reduced coder judgments of electability. This suggests that speakers should minimize "I"-statements to promote electability, a characteristic that is reflected more in older adults' speeches than young.

Age similarities in matching pro- and contra-hedonic emotional strategies to everyday scenarios

Older adults are motivated to maximize positive affect in the present. Young adults will purposely feel negative and high arousal emotions in order to achieve a goal. However, this type of contra-hedonic emotional alignment has not been extensively studied with older adults. We expected older adults are less likely than young adults to select high arousal and negative emotions within specific scenarios where those states could be useful. In two studies, participants selected the emotion they preferred in hypothetical problems that varied on the arousal and valence best suited for goal achievement. Young and older adults were equally likely to endorse affective strategies that matched both pro and contra-hedonic scenarios. While older adults may be generally motivated to avoid negative and high-arousing emotions, they are just as likely as young adults to indicate that these states could be helpful in certain situations.

YOUNG ADULTS STEREOTYPE OLDER SPEAKERS WHO ADOPTED A POWER POSE AS LESS COMPETENT COMPARED TO SUBMISSIVE OR CONTROL

Young adults (YA) frequently endorse age stereotypes (Levy, 2009). We examined whether older adult (OA) speakers influenced by embodied-cognition (“power posing”; Cuddy et al., 2015) would reduce YAs’ stereotype-related judgments. Following the Stereotype Content Model (SCM; Fiske et al., 2002), we hypothesized that OA who held a power pose prior to giving their speech would be rated as higher in Competency, Performance, and Electability, but not Warmth. Sixty-three YA viewed and rated 9 videos of OA performing speeches after modeling a pose (power, submissive, control). Within-subjects ANOVAs revealed embodiment condition differences for Performance (F2,124 = 207.76, ηp2 = .77). For ratings of Performance, speakers in the power condition were judged worse than either submissive or control (ps < .001). For Warmth ratings, power (M = 4.81, SD = .62) was worse than control (M = 5.07, SD = .89, p = .003, d = .34), but submissive (M = 4.97, SD = .87) was not significantly different from either group. These results suggest that YA may judge the Performance and Warmth of OA who adopted a power pose harsher because OA are not supposed to be powerful or adopt expansive postures (consistent with the SCM). In comparison, YA may be drawing upon the Representativeness Heuristic of OA in positions of power (e.g., Senators) when rating Electability and Competence.

An Age-Friendly University (AFU) assists with technology learning and social engagement among older adults and individuals with developmental disabilities

As an Age-Friendly University (AFU), University of Akron is striving to support lifelong learning. A collaborative research effort developed between aging researchers at the university and a government-sponsored pilot program aimed to provide learning opportunities for older adults (OA) and engagement for individuals with developmental disabilities (IDD). The present study assessed the success of a pilot program to increase comfort with technology and community engagement. OA and IDD participants met twice a month for 9 months to discuss how to use technology (e.g., an IPad). We assessed satisfaction, perceived changes in comfort with technology, perceived changes in connection with others, and motivations for participating with questionnaires and a structured interview. On average, participants reported very high satisfaction with the group, and moderate increases in comfort with technology and how connected they feel to others as a result of participating in the group. The most common motivations for participation were related to values, strengthening social ties, seeking to learn, and bringing joy to others. These findings suggest that the pilot was successful at improving community engagement. The involvement of the university in the assessment of this pilot program situates the university as an age-friendly partner for community efforts to support lifelong learning.

Lactobacillus accelerates ISCs regeneration to protect the integrity of intestinal mucosa through activation of STAT3 signaling pathway induced by LPLs secretion of IL-22

The regeneration of intestinal epithelial are maintained by continuous differentiation and proliferation of intestinal stem cells (ISCs) under physiological and pathological conditions. However, little is known about the regulatory effect of intestinal microbiota on its recovery ability to repair damaged mucosal barrier. In this study, we established intestinal organoids and lamina propria lymphocytes (LPLs) co-cultured system, plus mice experiments, to explore the protective effect of Lactobacillus reuteri D8 on integrity of intestinal mucosa. We found that only live L. reuteri D8 was effective in protecting the morphology of intestinal organoids and normal proliferation of epithelial stained with EdU under TNF-α treatment, which was also further verified in mice experiments. L. reuteri D8 colonized in the intestinal mucosa and ameliorated intestinal mucosa damage caused by DSS treatment, including improvement of body weight, colon length, pathological change, and proliferation level. The repair process stimulated by L. reuteri D8 was also accompanied with increased numbers of Lgr5+ and lysozyme+ cells both in intestinal organoids and mice intestine. Furthermore, we demonstrated that D8 metabolite indole-3-aldehyde stimulated LPLs to secret IL-22 through aryl hydrocarbon receptor (AhR) and then induced phosphorylation of STAT3 to accelerate proliferation of intestinal epithelial, thus recovering damaged intestinal mucosa. Our findings indicate L. reuteri protects intestinal barrier and activates intestinal epithelial proliferation, which sheds light on treatment approaches for intestinal inflammation based on ISCs with probiotics Lactobacillus and daily probiotic consumption in heath foods.

Ambient black carbon particulate matter in the coal region of Dhanbad, India

Light-absorbing, atmospheric particles have gained greater attention in recent years because of their direct and indirect impacts on regional and global climate. Atmospheric black carbon (BC) aerosol is a leading climate warming agent, yet uncertainties in the global direct aerosol radiative forcing remain large. Based on a year of aerosol absorption measurements at seven wavelengths, BC concentrations were investigated in Dhanbad, the coal capital of India. Coal is routinely burned for cooking and residential heat as well as in small industries. The mean daily concentrations of ultraviolet-absorbing black carbon measured at 370nm (UVBC) and black carbon measured at 880nm (BC) were 9.8±5.7 and 6.5±3.8μgm^-3, respectively. The difference between UVBC and BC, Delta-C, is an indicator of biomass or residential coal burning and averaged 3.29±4.61μgm^-3. An alternative approach uses the Ǻngstrom Exponent (AE) to estimate the biomass/coal and traffic BC concentrations. Biomass/coal burning contributed ~87% and high temperature, fossil-fuel combustion contributed ~13% to the annual average BC concentration. The post-monsoon seasonal mean UVBC values were 10.9μgm^-3 and BC of 7.2μgm^-3. Potential source contribution function analysis showed that in the post-monsoon season, air masses came from the central and northwestern Indo-Gangetic Plains where there is extensive agricultural burning. The mean winter UVBC and BC concentrations were 15.0 and 10.1μgm^-3, respectively. These higher values were largely produced by local sources under poor dispersion conditions. The direct radiative forcing (DRF) due to UVBC and BC at the surface (SUR) and the top of the atmosphere (TOA) were calculated. The mean atmospheric heating rates due to UVBC and BC were estimated to be 1.40°Kday^-1 and 1.18°Kday^-1, respectively. This high heating rate may affect the monsoon circulation in this region.

Constipation-Predominant Irritable Bowel Syndrome Females Have Normal Colonic Barrier and Secretory Function

OBJECTIVES

The objective of this study was to determine whether constipation-predominant irritable bowel syndrome (IBS-C) is associated with changes in intestinal barrier and secretory function.

METHODS

A total of 19 IBS-C patients and 18 healthy volunteers (all females) underwent saccharide excretion assay (0.1 g ¹³C mannitol and 1 g lactulose), measurements of duodenal and colonic mucosal barrier (transmucosal resistance (TMR), macromolecular and Escherichia coli Bio-Particle translocation), mucosal secretion (basal and acetylcholine (Ach)-evoked short-circuit current (Isc)), in vivo duodenal mucosal impedance, circulating endotoxins, and colonic tight junction gene expression.

RESULTS

There were no differences in the in vivo measurements of barrier function between IBS-C patients and healthy controls: cumulative excretion of ¹³C mannitol (0-2 h mean (s.e.m.); IBS-C: 12.1 (0.9) mg vs. healthy: 13.2 (0.8) mg) and lactulose (8-24 h; IBS-C: 0.9 (0.5) mg vs. healthy: 0.5 (0.2) mg); duodenal impedance IBS-C: 729 (65) Ω vs. healthy: 706 (43) Ω; plasma mean endotoxin activity level IBS-C: 0.36 (0.03) vs. healthy: 0.35 (0.02); and in colonic mRNA expression of occludin, zonula occludens (ZO) 1-3, and claudins 1-12 and 14-19. The ex vivo findings were consistent, with no group differences: duodenal TMR (IBS-C: 28.2 (1.9) Ω cm² vs. healthy: 29.8 (1.9) Ω cm²) and colonic TMR (IBS-C: 19.1 (1.1) Ω cm² vs. healthy: 17.6 (1.7) Ω cm²); fluorescein isothiocyanate (FITC)-dextran (4 kDa) and E. coli Bio-Particle flux. Colonic basal Isc was similar, but duodenal basal Isc was lower in IBS-C (43.5 (4.5) μA cm^-2) vs. healthy (56.9 (4.9) μA cm^-2), P=0.05. Ach-evoked ΔIsc was similar.

CONCLUSIONS

Females with IBS-C have normal colonic barrier and secretory function. Basal duodenal secretion is decreased in IBS-C.

Pharmaceutical interventions for obesity: a public health perspective

The prevalence of obesity, a major risk factor for many chronic diseases, has risen in most developed countries over the past several decades. The economic burden for both public and private health care systems is substantial. Although certain non-pharmaceutical interventions have been proven efficacious in specific populations, the lack of scalability has caused many of these programmes to fail in sustainably decreasing the percent of patients who are overweight or obese. The benefits of other interventions, such as pharmaceutical agents, medical devices and surgery, should therefore be carefully considered: this article focuses on the first of these strategies. Various pharmaceutical products have been plagued with safety concerns or patient non-adherence because of unpleasant side effects. Therefore, the need for additional antiobesity drugs that are both safe and effective is considerable. This article discusses the regulatory landscape for the development of new antiobesity compounds in the United States and Europe and considers the ramifications of greater or lesser regulatory burdens.

THE PRESERVATION OF LIVING RED BLOOD CELLS IN VITRO : II. THE TRANSFUSION OF KEPT CELLS

In order to determine the availability for functional uses of red cells kept in vitro by our methods, transfusion experiments have been carried out with rabbits by which a large part of their blood was replaced with kept rabbit cells suspended in Locke's solution. It has been found that erythrocytes preserved in mixtures of blood, sodium citrate, saccharose, and water for 14 days, and used to replace normal blood, will remain in circulation and function so well that the animal shows no disturbance, and the blood count, hemoglobin, and percentage of reticulated red cells remain unvaried. Cells kept for longer periods, though intact and apparently unchanged when transfused, soon leave the circulation. Animals in which this disappearance of cells is taking place on a large scale, remain healthy save for the progressing anemia. The experiments prove that, in the exsanguinated rabbit at least, transfusions of cells kept for a long time in vitro may be used to replace the blood lost, and that when the cells have been kept too long but are still intact they are disposed of without harm. The indications are that kept human cells could be profitably employed in the same way.

THE PRESERVATION OF LIVING RED BLOOD CELLS IN VITRO : I. METHODS OF PRESERVATION

The erythrocytes of some species are much damaged when handled in salt solutions, as in washing with the centrifuge after the ordinary method. The injury is mechanical in character. It may express itself in hemolysis only after the cells have been kept for some days. It is greatest in the case of dog corpuscles, and well marked with sheep and rabbit cells. The fragility of the red cells, as indicated by washing or shaking them in salt solution is different, not only for different species, but for different individuals. It varies independently of the resistance to hypotonic solutions. The protection of fragile erythrocytes during washing is essential if they are to be preserved in vitro for any considerable time. The addition of a little gelatin ((1/8) per cent) to the wash fluid suffices for this purpose, and by its use the period of survival in salt solutions of washed rabbit, sheep, and dog cells is greatly prolonged. Plasma, like gelatin, has marked protective properties. Though gelatin acts as a protective for red cells it is not preservative of them in the real sense. Cells do not last longer when it is added to the fluids in which they are kept. Locke's solution, though better probably than Ringer's solution, or a sodium chloride solution, as a medium in which to keep red cells, is ultimately harmful. The addition of innocuous colloids does not improve it. But the sugars, especially dextrose and saccharose, have a remarkable power to prevent its injurious action, and they possess, in addition, preservative qualities. Cells washed in gelatin-Locke's and placed in a mixture of Locke's solution with an isotonic, watery solution of a sugar remain intact for a long time,-nearly 2 months in the case of sheep cells. The kept cells go easily into suspension free of clumps, they pass readily through paper filters, take up and give off oxygen, and when used for the Wassermann reaction behave exactly as do fresh cells of the same individual. The best preservative solutions are approximately isotonic with the blood serum. If the cells are to be much handled gelatin should be present, for the sugars do not protect against mechanical injury. Different preservative mixtures are required for the cells of different species. Dog cells last longest in fluids containing dextrin as well as a sugar. The mixture best for red cells is not necessarily best for leukocytes. A simple and practical method of keeping rabbit and human erythrocytes is in citrated whole blood to which sugar solution is added. In citrated blood, as such, human red cells tend to break down rather rapidly, no matter what the proportion of citrate. Hemolysis is well marked after little more than a week. But in a mixture of 3 parts of human blood, 2 parts of isotonic citrate solution (3.8 per cent sodium citrate in water), and 5 parts of isotonic dextrose solution (5.4 per cent dextrose in water), the cells remain intact for about 4 weeks. Rabbit red cells can be kept for more than 3 weeks in citrated blood; and the addition of sugar lengthens the preservation only a little. The results differ strikingly with the amount of citrate employed. Hemolysis occurs relatively early when the smallest quantity is used that will prevent clotting. The optimum mixture has 3 parts of rabbit blood to 2 of isotonic citrate solution. In the second part of this paper experiments are detailed which prove that cells preserved by the methods here recorded function excellently when reintroduced into the body.

Inflammatory bowel disease: is it really just another break in the wall?

Although the critical factors necessary for IBD pathogenesis remain mysterious, interest in the potential role of defective epithelial barrier function continues to grow. New insight into the mechanisms responsible for barrier dysfunction in IBD may lead to understanding its contribution to disease development and progression.

Association of ventricular arrhythmias detected by implantable cardioverter defibrillator and ambient air pollutants in the St Louis, Missouri metropolitan area

BACKGROUND

It has previously been reported that the risk of ventricular arrhythmias is positively associated with ambient air pollution among patients with implantable cardioverter defibrillators (ICD) in Boston.

AIMS

To assess the association of community exposures to air pollution with ventricular arrhythmias in a cohort of ICD patients in metropolitan St Louis, Missouri.

METHODS

ICD detected episodes reported during clinical follow up were abstracted and reviewed by an electrophysiologist to identify ventricular arrhythmias. A total of 139 ventricular arrhythmias were identified among 56 patients. A case-crossover design was used with control periods matched on weekday and hour of the day within the same calendar month. Conditional logistic regression models were adjusted for temperature, barometric pressure, and relative humidity in the 24 hours preceding the event.

RESULTS

There was a significant (24%, 95% CI 7% to 44%) increase in risk of ventricular arrhythmias associated with each 5 ppb increase in mean sulphur dioxide and non-significantly increased risk (22%, 95% CI -6% to 60%; and 18%, 95% CI -7% to 50%) associated with increases in nitrogen dioxide (6 ppb) and elemental carbon (0.5 microg/m3), respectively in the 24 hours before the arrhythmia.

CONCLUSIONS

These results provide evidence of an association between ventricular arrhythmias and ambient air pollutants in St Louis. This is consistent with previous results from Boston, although the pollutants responsible for the increased risk are different.

Response of intestinal epithelial cells to Trichuris suis excretory-secretory products and the influence on Campylobacter jejuni invasion under in vitro conditions

We previously developed a swine animal model in which natural host resistance to Campylobacter jejuni is altered by experimental infection with low numbers of the nematode Trichuris suis. Pigs naturally colonized with C. jejuni experience colitis because of the invasion of the bacterium approximately 21 days after exposure to T. suis. To better understand the mechanism of T. suis-dependent C. jejuni colitis, we evaluated the effects of T. suis excretory-secretory products (ESPs) on intestinal epithelial cells (IECs) and the influence of ESP on C. jejuni invasion in IECs under in vitro conditions. Viability assays revealed a dose-dependent cytotoxic response in ESP-treated IECs, particularly IPEC-1 and INT407 cells. Transepithelial electrical resistance dropped significantly in IPEC-1 cells treated on apical and basolateral surfaces, but not in those treated only on apical surfaces. Using the gentamicin-killing assay, reduced numbers of intracellular C. jejuni were recovered from IECs treated with ESP at 1 mg protein/ml concentration. This observation can be at least partially explained by a novel antibacterial activity in ESP. Contrary to our hypothesis, ESP at subtoxic concentrations did not enhance invasion. In addition to mechanical damage from worms, these results suggest that soluble products released by T. suis contribute to IEC damage at the site of worm attachment.

2001 Harry M. Vars Research Award. Enteral nutrients alter enterocyte function within an in vitro model similar to an acute in vivo rat model during hypoxia

BACKGROUND

Early enteral nutrition in patients following traumatic injury is an important intervention. However, after shock-resuscitation, intestinal hypoperfusion persists despite adequate systemic resuscitation. Our previous in vivo rat studies indicate that hypoperfusion impairs mucosal function in the small intestine. Therefore, the current study sought to improve previous in vitro models by the following means: (1) We used Caco-2 monolayers stably transfected with the brush-border sodium-glucose co-transporter (SGLT-1); and (2) we created an environment that mimicked the physiologic enterocyte environment. We hypothesized that hypoxic alterations of epithelial function in an in vitro model are comparable to those of an in vivo rat model.

METHODS

After 21 days, monolayers were randomized to receive 24 hours of incubation in a normoxic or hypoxic environment. Cells were further randomized to receive 1 of 4 nutrient treatments: mannitol (an osmotic control), glucose (uses SGLT-1 and is metabolized), 3-O-methylglucose (3-O-mg; uses SGLT-1 and is not metabolized), or fructose (does not use SGLT-1 but can be metabolized).

RESULTS

Transepithelial resistance (p = .007) and short-circuit current (p = .05) were lower in hypoxic groups. When compared with normoxic groups, hypoxic groups had significantly impaired glucose (p < .001) but not glutamine transport, irrespective of nutrient treatment. Additionally, adenosine triphosphate/adenosine diphosphate ratio was reduced (p = .01) and lactate concentration was increased (p < .001) during hypoxia.

CONCLUSIONS

In summary, results from this in vitro study using Caco-2BBe cells stably transfected with SGLT-1 correspond to results obtained in the in vivo rat model. Therefore, this is an appropriate in vitro model in which to study cellular alterations caused by the hypoxic small intestine, with the goal of ensuring safe early enteral nutrition following traumatic injury.

Regulation of human jejunal transmucosal resistance and MLC phosphorylation by Na(+)-glucose cotransport

Na(+)- nutrient cotransport-dependent regulation of paracellular permeability has been demonstrated in rodent intestine and human intestinal epithelial cell lines. In cell lines this regulation is associated with phosphorylation of myosin II regulatory light chain (MLC). However, the subcellular localization of phosphorylated MLC during this regulation has not been studied and regulation of paracellular permeability and MLC phosphorylation has not been studied in isolated human intestine. To evaluate these events in human jejunum, isolated mucosa was mounted in Ussing chambers, characterized electrophysiologically, and then immunostained using anti-phosphorylated MLC and anti-total MLC antisera. MLC phosphorylation was assessed by calculating the ratio of anti-phosphorylated MLC signal to anti-total MLC signal within defined regions. Transmucosal resistance of mucosae without active Na(+)-glucose cotransport was 37 +/- 3% greater than that of mucosae with active Na(+)-glucose cotransport within 15 min. Quantitative double-label immunofluorescence showed that the phosphorylated MLC-to-total MLC ratio increased by 45 +/- 4% within the perijunctional actomyosin ring when Na(+)-glucose cotransport was active. Thus regulation of transmucosal resistance by Na(+)-glucose cotransport is accompanied by increased MLC phosphorylation within the perijunctional actomyosin ring. These data support the proposed critical role of the perijunctional cytoskeleton in physiological regulation of human small intestinal paracellular permeability.

NHE3-dependent cytoplasmic alkalinization is triggered by Na(+)-glucose cotransport in intestinal epithelia

Cytoplasmic pH (pH(i)) was evaluated during Na(+)-glucose cotransport in Caco-2 intestinal epithelial cell monolayers. The pH(i) increased by 0.069 +/- 0.002 within 150 s after initiation of Na(+)-glucose cotransport. This increase occurred in parallel with glucose uptake and required expression of the intestinal Na(+)-glucose cotransporter SGLT1. S-3226, a preferential inhibitor of Na(+)/H(+) exchanger (NHE) isoform 3 (NHE3), prevented cytoplasmic alkalinization after initiation of Na(+)-glucose cotransport with an ED(50) of 0.35 microM, consistent with inhibition of NHE3, but not NHE1 or NHE2. In contrast, HOE-694, a poor NHE3 inhibitor, failed to significantly inhibit pH(i) increases at <500 microM. Na(+)-glucose cotransport was also associated with activation of p38 mitogen-activated protein (MAP) kinase, and the p38 MAP kinase inhibitors PD-169316 and SB-202190 prevented pH(i) increases by 100 +/- 0.1 and 86 +/- 0.1%, respectively. Conversely, activation of p38 MAP kinase with anisomycin induced NHE3-dependent cytoplasmic alkalinization in the absence of Na(+)-glucose cotransport. These data show that NHE3-dependent cytoplasmic alkalinization occurs after initiation of SGLT1-mediated Na(+)-glucose cotransport and that the mechanism of this NHE3 activation requires p38 MAP kinase activity. This coordinated regulation of glucose (SGLT1) and Na(+) (NHE3) absorptive processes may represent a functional activation of absorptive enterocytes by luminal nutrients.

African Americans with genotype 1 treated with interferon for chronic hepatitis C have a lower end of treatment response than Caucasians

African Americans as a group have a higher incidence of chronic hepatitis C (CHC) than Caucasians but are often under-represented in clinical trials used to define response rates to interferon therapy. The aim of this study was to compare African Americans with Caucasians with respect to end-of-treatment response to interferon. This retrospective study had 61 African Americans and 49 Caucasians with CHC. All patients were treated for at least 12 weeks with interferon-alpha2b (Intron A) thrice weekly. End-of-treatment response was defined as three consecutive nondetectable HCV RNA measurements at least 1 month apart. Sustained response was defined as a negative serum HCV RNA 6 months after end of treatment. Of the 110 patients, 19 achieved an end-of-treatment response (17%) but only four achieved a sustained response (4/110=4%). Of the patients achieving a sustained response, one was genotype 1 (male Caucasian), three were genotype 2/3 with four patients having no follow-up information. The end-of-treatment response was 7% for patients with genotype 1 and 71% for genotype non-1 (P < 0.005 for genotype non-1). The end-of-treatment response was significantly higher in Caucasians (14/49=31%) compared with African Americans (5/61=8%; P < 0.05). A lower response rate in African Americans with genotype 1 in contrast to Caucasians was the primary reason for the difference in end-of-treatment response (1/45=2% vs. 5/33=15%, P < 0.05). Hence, interferon treatment resulted in a poor sustained response rate in the group of patients representative of the urban populations with the highest prevalence of hepatitis C. A genotype other than type 1 was the strongest predictor of end-of-treatment response in patients treated but over 86% of patients in this urban clinic were genotype 1. Caucasians were more likely to respond than African Americans, especially in patients with genotype 1.

Cloning of a novel EGFR-related peptide: a putative negative regulator of EGFR

Although epidermal growth factor receptor (EGFR) plays a key role in regulating cell proliferation, differentiation, and transformation in many tissues, little is known about the factor(s) that may modulate its function. We have isolated a cDNA clone from the rat gastroduodenal mucosa whose full length revealed 1,958 bp that contained 227 bp of 5'-untranslated region (UTR) and an open-reading frame encoding 479 amino acids, followed by 290 bp of 3'-UTR. It showed ~85% nucleotide homology to the external domain of the rat EGFR. We refer to the product of the newly isolated cDNA as EGFR-related protein (ERRP). In Northern blot analysis with poly(A)(+) RNA from different rat tissues, ERRP cDNA hybridized to several mRNA transcripts with the strongest reaction noted with a transcript of approximately 2 kb. Maximal expression of the 2-kb mRNA transcript was observed in the small intestine, followed by colon, liver, gastric mucosa, and other tissues. Transfection of ERRP cDNA into a colon cancer cell line, HCT116, resulted in a marked reduction in proliferation in monolayer and colony formation in soft agar compared with the vector-transfected controls. In another colon cancer cell line, Caco-2, with a tetracycline-regulated promoter system, induction of ERRP expression in the absence of doxycycline was associated with a marked reduction in EGFR activation and proliferation. We conclude that the ERRP cDNA may represent a new member of the EGFR gene family and that ERRP plays a role in regulating cell proliferation by modulating the function of EGFR.

Clostridium difficile toxins disrupt epithelial barrier function by altering membrane microdomain localization of tight junction proteins

The anaerobic bacterium Clostridium difficile is the etiologic agent of pseudomembranous colitis. C. difficile toxins TcdA and TcdB are UDP-glucosyltransferases that monoglucosylate and thereby inactivate the Rho family of GTPases (W. P. Ciesla, Jr., and D. A. Bobak, J. Biol. Chem. 273:16021-16026, 1998). We utilized purified reference toxins of C. difficile, TcdA-10463 (TcdA) and TcdB-10463 (TcdB), and a model intestinal epithelial cell line to characterize their influence on tight-junction (TJ) organization and hence to analyze the mechanisms by which they contribute to the enhanced paracellular permeability and disease pathophysiology of pseudomembranous colitis. The increase in paracellular permeability induced by TcdA and TcdB was associated with disorganization of apical and basal F-actin. F-actin restructuring was paralleled by dissociation of occludin, ZO-1, and ZO-2 from the lateral TJ membrane without influencing the subjacent adherens junction protein, E-cadherin. In addition, we observed decreased association of actin with the TJ cytoplasmic plaque protein ZO-1. Differential detergent extraction and fractionation in sucrose density gradients revealed TcdB-induced redistribution of occludin and ZO-1 from detergent-insoluble fractions constituting "raft-like" membrane microdomains, suggesting an important role of Rho proteins in maintaining the association of TJ proteins with such microdomains. These toxin-mediated effects on actin and TJ structure provide a mechanism for early events in the pathophysiology of pseudomembranous colitis.

Altered myosin light-chain phosphorylation in resting platelets from premenopausal women with diabetes

Gender-related differences in the rate of coronary heart disease (CHD) between premenopausal women and men are greatly diminished in women with diabetes mellitus (DM). This may be related, in part, to altered platelet function in premenopausal diabetic women. Hyperglycemia may contribute to increase platelet aggregation through enhancement of oxidative stress, increased nitric oxide (NO) destruction, and increased myosin light-chain (MLC) phosphorylation (MLC-P). Accordingly, we investigated functional and biochemical parameters of platelet function in 32 women (14 premenopausal and postmenopausal controls and 18 age-matched patients with DM); platelet MLC-P and cyclic guanosine monophosphate ([cGMP] reflecting NO) were assessed. Other parameters including age, body mass index (BMI), waist to hip ratio, total cholesterol, and platelet count were not different in the control and diabetic groups. In the premenopausal women, baseline MLC-P was lower in women with DM versus the control group (P = .02). GMP levels were similar in the two groups at baseline (22.7 +/- 3 fmol/mL in controls v 23.1 +/- 3 fmol/mL in diabetic subjects) and 3 minutes after insulin exposure. The platelet content of ascorbic acid (AA), an endogenous antioxidant compound, was elevated in premenopausal women with DM (P = .02) compared with the controls. Despite similar estradiol (beta,E2) levels, platelets of premenopausal women with DM exhibited reduced MLC-P. This paradoxic difference may be accounted for by an increase in platelet AA, as this suggests decreased platelet oxidative stress in this patient population. These observations indicate that an altered redox state and associated MLC-P of platelets does not contribute to enhanced platelet aggregation and CHD in premenopausal women with DM.

Transepithelial resistance can be regulated by the intestinal brush-border Na(+)/H(+) exchanger NHE3

Initiation of intestinal Na(+)-glucose cotransport results in transient cell swelling and sustained increases in tight junction permeability. Since Na(+)/H(+) exchange has been implicated in volume regulation after physiological cell swelling, we hypothesized that Na(+)/H(+) exchange might also be required for Na(+)-glucose cotransport-dependent tight junction regulation. In Caco-2 monolayers with active Na(+)-glucose cotransport, inhibition of Na(+)/H(+) exchange with 200 microM 5-(N,N-dimethyl)- amiloride induced 36 +/- 2% increases in transepithelial resistance (TER). Evaluation using multiple Na(+)/H(+) exchange inhibitors showed that inhibition of the Na(+)/H(+) exchanger 3 (NHE3) isoform was most closely related to TER increases. TER increases due to NHE3 inhibition were related to cytoplasmic acidification because cytoplasmic alkalinization with 5 mM NH(4)Cl prevented both cytoplasmic acidification and TER increases. However, NHE3 inhibition did not affect TER when Na(+)-glucose cotransport was inhibited. Myosin II regulatory light chain (MLC) phosphorylation decreased up to 43 +/- 5% after inhibition of Na(+)/H(+) exchange, similar to previous studies that associate decreased MLC phosphorylation with increased TER after inhibition of Na(+)-glucose cotransport. However, NHE3 inhibitors did not diminish Na(+)-glucose cotransport. These data demonstrate that inhibition of NHE3 results in decreased MLC phosphorylation and increased TER and suggest that NHE3 may participate in the signaling pathway of Na(+)-glucose cotransport-dependent tight junction regulation.

Noninvasive in vivo analysis of human small intestinal paracellular absorption: regulation by Na+-glucose cotransport

Activation of intestinal Na+-glucose cotransport increases paracellular movement of inert tracers in cultured monolayers, isolated rodent intestinal mucosae, and in rodents in vivo. However, not all studies have demonstrated comparable effects on human intestinal paracellular absorption. We sought to assess the effects of Na+-glucose cotransport on paracellular absorption in human beings using a simple noninvasive assay. Study subjects drank six 200-ml doses of test solution, composed of 0.8% w/v creatinine (sufficient to overwhelm endogenous creatinine) in 277 mM glucose or mannitol and urine was collected. Intestinal creatinine absorption is paracellular. Once absorbed, creatinine is cleared into the urine. Therefore, urinary creatinine recovery reflects intestinal paracellular creatinine absorption. Total urinary creatinine recovery was 55% +/- 4% of creatinine ingested with glucose and 38% +/- 9% of creatinine ingested with mannitol (p < 0.001). Thus, intestinal paracellular absorption of creatinine is increased by the presence of luminal glucose. Our results are consistent with in vivo human regulation of mucosal permeability by Na+-glucose cotransport.

Molecular physiology and pathophysiology of tight junctions. IV. Regulation of tight junctions by extracellular stimuli: nutrients, cytokines, and immune cells

The epithelial lining of the gastrointestinal tract forms a regulated, selectively permeable barrier between luminal contents and the underlying tissue compartments. Permeability across the epithelium is, in part, determined by the rate-limiting barrier of the paracellular pathway-the most apical intercellular junction referred to as the tight junction (TJ). The TJ is composed of a multiprotein complex that affiliates with the underlying apical actomyosin ring. TJ structure and function, and therefore epithelial permeability, are influenced by diverse physiological and pathological stimuli; here we review examples of such stimuli that are detected at the cell surface. For example, luminal glucose induces an increase in paracellular permeability to small molecules. Similarly, but by other means, cytokines and leukocytes in the vicinity of the epithelium also regulate TJ structure and paracellular permeability by influencing the TJ protein complex and/or its association with the underlying actin cytoskeleton.

Mink cell focus-forming murine leukemia virus infection induces apoptosis of thymic lymphocytes

In a previous study we identified the subpopulations of thymus cells that were infected by the lymphomagenic MCF13 murine leukemia virus (MLV) (F. K. Yoshimura, T. Wang, and M. Cankovic, J. Virol. 73:4890-4898, 1999) and observed an effect on thymus size by virus infection. In this report we describe our results which demonstrate that MCF13 MLV infection of thymuses reduced the number of T lymphocytes in this organ. Histological examination showed diffuse lymphocyte depletion, which was most striking in the CD4(+) CD8(+) lymphocyte-enriched cortical zone. Consistent with this, flow cytometric analysis showed that the lymphocytes which were depleted were predominantly the immature CD3(-) CD4(+) CD8(+) and CD3(+) CD4(+) CD8(+) cells. A comparison of the percentages of live, apoptotic, and dead cells of the gp70(+) and gp70(-) thymic lymphocytes suggested that this effect on thymus cellularity is a result of virus infection. Studies of the survival of thymic T lymphocytes in culture showed that cells from MCF13 MLV-inoculated mice underwent greater apoptosis and death than cells from control animals. Assays for apoptosis included 7-amino-actinomycin D staining, DNA fragmentation, and cleavage of caspase-3 and poly(ADP-ribose) polymerase proenzymes. Our results suggest that apoptosis of thymic lymphocytes by virus infection is an important step in the early stages of MCF13 MLV tumorigenesis.

'Putting the squeeze' on the tight junction: understanding cytoskeletal regulation

The apical perijunctional actomyosin ring of epithelia is structurally associated with the tight junction. The functional association between the tight junction and the perijunctional actomyosin ring was initially described in studies using pharmacological agents that disrupt microfilaments. More recently, this interaction has been studied in physiological, pathophysiological, and molecular models of tight junction regulation. These studies have demonstrated the central role of actomyosin contraction in tight junction regulation. With the identification of novel tight junction proteins and characterization of their protein:protein interactions comes the promise of detailed understanding of the molecular interactions that mediate tight junction regulation.

Show me the pathway! Regulation of paracellular permeability by Na(+)-glucose cotransport

The physiological impact of Na(+)-nutrient cotransport-dependent regulation of intestinal tight junction permeability has been controversial. Nonetheless, increased permeability of small intestinal mucosae and enterocyte tight junctions as a consequence of Na(+)-nutrient cotransport has been documented by a significant number of in vivo and in vitro studies. Some details of the intracellular signaling events that regulate this process have been described recently. The aims of this article are to: (i) review studies of tight junction regulation and paracellular nutrient absorption in mammalian intestine, (ii) identify potential applications of tight junction regulation, and (iii) summarize recent progress in defining molecular mechanisms that lead to altered tight junction permeability.

Pericolonic tumor deposits in patients with T3N+MO colon adenocarcinomas: markers of reduced disease free survival and intra-abdominal metastases and their implications for TNM classification

BACKGROUND

A pericolonic tumor deposit (PTD) is a grossly palpated adenocarcinomas within pericolonic adipose tissue not within a lymph node. The source and prognostic significance of PTDs has not been well defined.

METHODS

The authors studied 418 T3N+M0 colon adenocarcinomas to determine the frequency and significance of PTDs. They also step-sectioned 30 PTDs to determine their origin and assist in their optimum TNM classification.

RESULTS

Seventy-one (18%) of 400 consecutively examined cases had PTDs. The actuarial 1-, 2-, and 5-year disease free survival rates were significantly lower among patients with a PTD. PTDs, regardless of size, significantly impacted disease free survival. Increasing numbers of PTDs was associated with shorter disease free survival. Adenocarcinoma grade, a PTD, increasing numbers of PTDs, and number of lymph node metastases were independently associated with shorter disease free survival. The likelihood of extrahepatic abdominal failure was proportionally greater with increasing numbers of PTDs. Adenocarcinoma was observed in perineural, peri-large vessel, or intravascular locations in step-sectioned PTDs.

CONCLUSIONS

A PTD is a perineural, perivascular, or intravascular tumor extension beyond the muscularis propria. They are distinct from lymph node metastases and should not be considered their prognostic equivalent. The disease free survival impact of even small PTDs was significant, suggesting that PTDs of all sizes should be considered a single entity. TNM classification of PTDs as lymph node metastases or discontinuous tumor extension is probably not accurate. The number and greatest dimension of PTDs should be reported separately from lymph node metastases.

Pericolonic tumor deposits in patients with T3N+MO colon adenocarcinomas: markers of reduced disease free survival and intra-abdominal metastases and their implications for TNM classification

BACKGROUND

A pericolonic tumor deposit (PTD) is a grossly palpated adenocarcinomas within pericolonic adipose tissue not within a lymph node. The source and prognostic significance of PTDs has not been well defined.

METHODS

The authors studied 418 T3N+M0 colon adenocarcinomas to determine the frequency and significance of PTDs. They also step-sectioned 30 PTDs to determine their origin and assist in their optimum TNM classification.

RESULTS

Seventy-one (18%) of 400 consecutively examined cases had PTDs. The actuarial 1-, 2-, and 5-year disease free survival rates were significantly lower among patients with a PTD. PTDs, regardless of size, significantly impacted disease free survival. Increasing numbers of PTDs was associated with shorter disease free survival. Adenocarcinoma grade, a PTD, increasing numbers of PTDs, and number of lymph node metastases were independently associated with shorter disease free survival. The likelihood of extrahepatic abdominal failure was proportionally greater with increasing numbers of PTDs. Adenocarcinoma was observed in perineural, peri-large vessel, or intravascular locations in step-sectioned PTDs.

CONCLUSIONS

A PTD is a perineural, perivascular, or intravascular tumor extension beyond the muscularis propria. They are distinct from lymph node metastases and should not be considered their prognostic equivalent. The disease free survival impact of even small PTDs was significant, suggesting that PTDs of all sizes should be considered a single entity. TNM classification of PTDs as lymph node metastases or discontinuous tumor extension is probably not accurate. The number and greatest dimension of PTDs should be reported separately from lymph node metastases.

Ethnicity and socioeconomic status: impact on cardiovascular activity at rest and during stress in youth with a family history of hypertension

OBJECTIVE

The purpose of the present study was to examine the potential interaction of ethnicity and SES on hemodynamic functioning at rest and during acute stress in normotensive adolescents with a family history of essential hypertension (EH).

DESIGN

The influences of ethnicity and socioeconomic status (SES) on cardiovascular function were evaluated at rest and in response to five different laboratory stressors.

METHODS

110 (50 female) Caucasian and 162 (85 female) African-American normotensive youth (initial age 11.2+/-2.4 years) with a family history of essential hypertension (EH) were tested on two occasions, an average of 2.5 years apart. Based on previous findings, it was predicted that African Americans, particularly those of low SES, would exhibit higher resting blood pressure (BP) and greater cardiovascular reactivity to acute laboratory stressors than would Caucasians.

RESULTS

As predicted, African-American youth exhibited higher resting diastolic blood pressure (DBP) and total peripheral resistance (TPR) than Caucasians on both visits (both Ps<.04). African Americans exhibited greater systolic blood pressure (SBP) reactivity than did Caucasians to the video game stressor during both lab visits (both Ps<.02) and greater heart rate reactivity during the first lab visit (P<.01). African Americans exhibited greater SBP and/or DBP, and TPR reactivity to the cold pressor during the first lab visit and the parent-child discussion during the second visit (all Ps<.03).

CONCLUSION

As predicted, African Americans exhibited higher resting BP and TPR, and greater cardiovascular reactivity than Caucasians. Although not in the predicted direction, a pattern of interactions began to emerge on the second evaluation. For example, upper SES youth exhibited greater heart rate reactivity compared to all other groups on the social competence interview and parent-child discussion stressors. Further study is needed to clarify the role cardiovascular reactivity may play in the link between ethnicity, SES, and cardiovascular disease risk.

Aging alters gastric mucosal responses to epidermal growth factor and transforming growth factor-alpha

Administration of pharmacological doses of epidermal growth factor (EGF) or transforming growth factor-alpha (TGF-alpha) in young rats stimulates gastric mucosal proliferation, but, in aged rats, the same treatment inhibits proliferation. This may be due to enhanced ligand-induced internalization of EGF receptor (EGFR). In support of this, we demonstrated that although a single injection of EGF (10 microg/kg) or TGF-alpha (5 microg/kg) in young (4-6 mo old) rats greatly increased membrane-associated EGFR tyrosine kinase activity, the same treatment slightly inhibited the enzyme activity in aged (24 mo old) rats. This treatment also produced a greater abundance of punctate cytoplasmic EGFR staining in gastric epithelium of aged rats, consistent with EGFR internalization. In vitro analyses demonstrated that exposure of isolated gastric mucosal cells from aged but not young rats to 100 pM TGF-alpha resulted in marked increases in intracellular EGFR tyrosine kinase activity and that induction of EGFR tyrosine kinase activity in mucosal membranes from aged rats occurred at doses 1,000-fold less than those required in young rats. Our data suggest that aging enhances sensitivity of the gastric mucosa to EGFR ligands. This may partly explain EGFR-mediated inhibition of gastric mucosal proliferation in aged rats.

Preoperative chemoradiotherapy alters the expression and prognostic significance of adhesion molecules in Barrett's-associated adenocarcinoma

A variety of prognostic markers have been related to decreased patient survival in patients with epithelial malignancies. These include expression of the homotypic adhesion molecule E-cadherin (ECAD) and the hyaluronic acid receptor CD44. Expression of ECAD and CD44 was evaluated in Barrett's-associated adenocarcinoma (BAd) from 67 patients. Expression was determined by immunoperoxidase staining and graded semiquantitatively based on the proportion of positively stained cells. These data were then correlated with clinical and pathological parameters, including the presence or absence of chemoradiotherapy (chemrad) and patient survival. There were 56 men and 11 women (mean age, 62 years). Thirty-nine (58%) patients received preoperative chemrad. ECAD expression was detected in all (100%) tumors. The ECAD staining grade did not correlate with other pathological features of the tumors. However, ECAD staining was significantly increased in BAd of patients who received chemrad (P = .003), in comparison with those who did not, and in individual patients when prechemrad biopsies and postchemrad resection specimens were compared (P = .04). In terms of prognosis, increased ECAD expression was associated with shortened patient survival only in BAd patients who had received chemrad (univariate analysis of chemrad patients with stage I and II BAd, P = .02). ECAD expression was not significantly associated with survival in BAd patients who did not receive chemrad. CD44 expression was detected in 88% of cases. CD44 expression did not correlate with any of the pathological features of the tumors or with chemrad status. Increased expression of CD44 was significantly associated with shortened patient survival in chemrad patients only (univariate analysis P = .03, multivariate analysis P = .04), although a strong trend was observed when all patients were analyzed regardless of chemrad status (P = .07). The results of this study indicate that chemrad alters the expression of ECAD in BAd. Thus, the prognostic utility of ECAD expression must be evaluated in the context of chemrad status. CD44 also may be a valuable prognostic marker in BAd.

Pathologic prognostic factors in esophageal squamous cell carcinoma: a follow-up study of 74 patients with or without preoperative chemoradiation therapy

One of the primary goals of pathologic examination of esophageal squamous cell carcinoma resection specimens is to provide information regarding morphologic features which can help prognosticate and guide management of affected patients. The purpose of this study was to determine the prognostic utility of a variety of histopathologic prognostic factors in patients with esophageal squamous cell carcinoma with and without preoperative chemotherapy and radiotherapy (chemrad). Multiple clinical and histologic features such as peri-tumoral lymphocytic infiltrate, Crohn's-like lymphoid reaction, degree of residual tumor, mitosis per 1000 cells, tumor differentiation, lymphatic/vascular invasion, perineural invasion, desmoplastic reaction, and tumor growth pattern were evaluated in patients with (53) and without (21) preoperative chemrad and correlated with survival (mean follow-up, 25 mo). Data were analyzed for the entire cohort and for each separate treatment group by univariate and multivariate analysis. Patients who received chemrad showed no significant survival benefit (hazard ratio = 2.5, P = .10). In the whole cohort of patients, higher pathologic stage (P = .04), poor tumor differentiation (P = .003), increased mitotic count (P = .005), perineural invasion (P = .01), lymphatic/vascular invasion (P = .002), tumor size (P = .05), and absence of a Crohn's-like lymphoid reaction (P = .05) were significantly associated with poor survival by univariate analysis. In multivariate analysis, poor tumor differentiation (P = .005), high mitotic count (P = .01), and vascular invasion (P = .03) were important prognostic features, independent of pathologic stage, for the entire cohort. In the chemrad group only, tumor size (in patients with macroscopic residual tumor) (P = .05), lymph node metastasis (P = .03), mitotic count (P = .01), and lymphatic/vascular invasion (P = .02) were significant prognostic indicators by univariate analysis. Upon multivariate analysis, only lymphatic/vascular invasion (P = .02) and mitotic rate (P = .01) were independent predictors of survival. In the nonchemrad group, only tumor differentiation was significant by both univariate (P = .008) and multivariate analysis (P = .03). The differences in pathologic prognostic factors between chemrad and nonchemrad treated cases suggests that chemrad has a significant effect on the biologic properties of these tumors.