CRP Monitoring in Early Hospitalization: Implications for Predicting Outcomes in Patients with COVID-19.

Elevated C-reactive protein (CRP) levels have been associated with poorer COVID-19 outcomes. While baseline CRP levels are higher in women, obese individuals, and older adults, the relationship between CRP, sex, body mass index (BMI), age, and COVID-19 outcomes remains unknown. To investigate, we performed a retrospective analysis on 824 adult patients with COVID-19 admitted during the first pandemic wave, of whom 183 (22.2%) died. The maximum CRP value over the first five hospitalization days better predicted hospitalization outcome than the CRP level at admission, as a maximum CRP > 10 mg/dL independently quadrupled the risk of death (p < 0.001). Males (p < 0.001) and patients with a higher BMI (p = 0.001) had higher maximum CRP values, yet CRP levels did not impact their hospitalization outcome. While CRP levels did not statistically mediate any relation between sex, age, or BMI with clinical outcomes, age impacted the association between BMI and the risk of death. For patients 60 or over, a BMI < 25 kg/m2 increased the risk of death (p = 0.017), whereas the reverse was true for patients <60 (p = 0.030). Further impact of age on the association between BMI, CRP, and the risk of death could not be assessed due to a lack of statistical power but should be further investigated.

Trajectories of psychological distress among individuals exposed to the 9/11 World Trade Center disaster.

BACKGROUND: Individuals present in lower Manhattan during the 9/11 World Trade Center (WTC) disaster suffered from significant physical and psychological trauma. Studies of longitudinal psychological distress among those exposed to trauma have been limited to relatively short durations of follow-up among smaller samples. METHODS: The current study longitudinally assessed heterogeneity in trajectories of psychological distress among WTC Health Registry enrollees - a prospective cohort health study of responders, students, employees, passersby, and residents in the affected area (N = 30 839) - throughout a 15-year period following the WTC disaster. Rescue/recovery status and exposure to traumatic events of 9/11, as well as sociodemographic factors and health status, were assessed as risk factors for trajectories of psychological distress. RESULTS: Five psychological distress trajectory groups were found: none-stable, low-stable, moderate-increasing, moderate-decreasing, and high-stable. Of the study sample, 78.2% were classified as belonging to the none-stable or low-stable groups. Female sex, being younger at the time of 9/11, lower education and income were associated with a higher probability of being in a greater distress trajectory group relative to the none-stable group. Greater exposure to traumatic events of 9/11 was associated with a higher probability of a greater distress trajectory, and community members (passerby, residents, and employees) were more likely to be in greater distress trajectory groups - especially in the moderate-increasing [odds ratios (OR) 2.31 (1.97-2.72)] and high-stable groups [OR 2.37 (1.81-3.09)] - compared to the none-stable group. CONCLUSIONS: The current study illustrated the heterogeneity in psychological distress trajectories following the 9/11 WTC disaster, and identified potential avenues for intervention in future disasters.

A Data Science Approach to Estimating the Frequency of Driving Cessation Associated Suicide in the US: Evidence From the National Violent Death Reporting System.

Driving cessation is a common transition experienced by aging adults that confers both a symbolic and literal loss of independence due to the central role of automobiles for mobility in the US. Prior research has shown that driving cessation has negative implications for mental health, social participation, and access to healthcare. Given these sequelae of driving cessation and prior work showing that late-life transitions related to independence (e.g., transitioning into residential care) are associated with suicide, we sought to estimate the frequency of driving cessation associated suicide. Data include suicide (n = 59,080) and undetermined (n = 6,862) deaths aged ≥55 from the National Violent Death Reporting System (NVDRS, 2003-2017). Each case in the NVDRS has both quantitative data (e.g., demographic characteristics) and qualitative text narratives, derived from coroner/medical examiner reports, which describe the most salient circumstances and features of each death. To identify cases associated with driving cessation, we employed a supervised random forest algorithm to develop a Natural Language Processing (NLP) classifier. Identified driving cessation associated cases were then categorized and characterized using descriptive statistics and qualitative content analysis. From 2003 to 2017, there were an estimated 305 cases of suicide/undetermined deaths associated with driving cessation in the NVDRS, representing 0.04% of all cases. Cases associated with driving cessation were older, more likely to be male, more likely to have a physical health problem, more likely to have experienced a recent crisis, and more likely to have lived in a rural county than other decedents. Qualitative analysis identified functional impairment, alcohol-related driving limitations, loss of employment, and recent car accidents as common themes among cases associated with driving cessation. This analysis illustrates the utility of NLP in identifying novel correlates of suicide in later life. Although driving cessation associated suicide is a rare outcome, further research is warranted on understanding the conditions under which driving cessation is associated with suicidal behavior, and how to support the well-being of aging adults during these types of major life transitions.

Not discussed: Inequalities in narrative text data for suicide deaths in the National Violent Death Reporting System.

BACKGROUND: The rate of suicide in the US has increased substantially in the past two decades, and new insights are needed to support prevention efforts. The National Violent Death Reporting System (NVDRS), the nation's most comprehensive registry of suicide mortality, has qualitative text narratives that describe salient circumstances of these deaths. These texts have great potential for providing novel insights about suicide risk but may be subject to information bias. OBJECTIVE: To examine the relationship between decedent characteristics and the presence and length of NVDRS text narratives (separately for coroner/medical examiner (C/ME) and law enforcement (LE) reports) among 233,108 suicide and undetermined deaths from 2003-2017. METHODS: Generalized estimating equations (GEE) logistic and quasi-Poisson modeling was used to examine variation in the narratives (proportion of missing texts and character length of the non-missing texts, respectively) as a function of decedent age, sex, race/ethnicity, education, marital status, military history, and homeless status. Models adjusted for site, year, location of death, and autopsy status. RESULTS: The frequency of missing narratives was higher for LE vs. C/ME texts (19.8% vs. 5.2%). Decedent characteristics were not consistently associated with missing text across the two types of narratives (i.e., Black decedents were more likely to be missing the LE narrative but less likely to be missing the C/ME narrative relative to non-Hispanic whites). Conditional on having a narrative, C/ME were significantly longer than LE (822.44 vs. 780.68 characters). Decedents who were older, male, had less education and some racial/ethnic minority groups had shorter narratives (both C/ME and LE) than younger, female, more educated, and non-Hispanic white decedents. CONCLUSION: Decedent characteristics are significantly related to the presence and length of narrative texts for suicide and undetermined deaths in the NVDRS. Findings can inform future research using these data to identify novel determinants of suicide mortality.

Implicit and Explicit Beliefs About the Effectiveness of Psychotherapy vs. Medication: A Large-Scale Examination and Replication.

ABSTRACT: One exploratory study (N = 10,335) and one preregistered replication and extension study (N = 6648) evaluated implicit and explicit beliefs in the effectiveness of psychotherapy versus medication, and whether these beliefs vary as a function of demographics, mental health difficulties, and treatment experiences. Data were collected from a sample of visitors to a mental health research website who completed the Therapy vs. Medication Effectiveness Implicit Association Test (IAT). The IAT demonstrated evidence of convergent validity with two measures of explicit therapy versus medication effectiveness beliefs. Across both studies, individuals held greater implicit and explicit beliefs that therapy is more effective than medication, and individuals who were Black (versus all other races, excluding "other/unknown") and who had experienced past (versus current) mental health difficulties had stronger implicit and explicit beliefs in the effectiveness of therapy versus medication. More work is needed to understand how these differences in beliefs arise, as well as to evaluate the clinical utility of this novel measure.

State Variation in Long-Term Care Availability, Regulation, and Cost and Suicide Mortality Among Older Adults in the United States: 2010-2015.

OBJECTIVES: Residential long-term care (LTC) facilities may be key settings for the prevention of suicide among older adults; however, little is known about the relationship between statewide policies determining characteristics of LTC facilities and suicide mortality. The primary goal of this study was to evaluate the association between state policies regarding availability, regulation, and cost of LTC and suicide mortality among adults aged 55 and older in the United States over a 5-year period. DESIGN: Longitudinal ecological study. SETTING AND PARTICIPANTS: LTC residents from 16 states reporting mortality data to the National Violent Death Reporting System (NVDRS) from 2010 to 2015. METHODS: We linked suicide data from the NVDRS and data sources on LTC services and regulations for 16 states. We applied a natural language-processing algorithm to identify suicide deaths related to LTC. We used fixed effect regression models to assess whether state variation in LTC characteristics is related to variation in the rate of suicide (both overall and related to LTC) among older adults. RESULTS: There were 25,040 suicides among those aged 55 and older reported to the NVDRS during the study period; 382 suicides were determined to be associated with LTC in some manner. After adjusting for state-level characteristics, greater average nursing home capacity was significantly associated with increase in the cumulative incidence of suicide related to LTC (ß = 0.087, SE = 0.026, P < .01), but not overall suicide incidence. Neither cost nor regulation measures were significantly associated with state-level LTC-related suicide incidence. CONCLUSIONS AND IMPLICATIONS: State-level variations in LTC facility capacity are related to variation in LTC-related suicide incidence among older adults. Given the challenges of preventing suicide among older adults through facility- or individual-level interventions, policies governing the features and provision of LTC services may therefore serve as a means for public health suicide prevention.

Suicide Among Older Adults Living in or Transitioning to Residential Long-term Care, 2003 to 2015.

Importance: Almost 25% of Medicare beneficiaries live in residential long-term care (LTC) (eg, independent or assisted living facility or nursing home). There are few reliable statistics on completed suicide in LTC, in part because of data limitations. Objectives: To estimate the number of suicides associated with residential LTC (ie, among persons in a facility, transitioning into or out of a facility, or otherwise associated with LTC) among adults 55 and older and, secondarily, to identify whether machine learning tools could improve the quality of suicide surveillance data. Design, Setting, and Participants: Cross-sectional epidemiologic study (conducted in 2018) of restricted-access data from the National Violent Death Reporting System (NVDRS) (2003-2015) using restricted-access case narratives from suicides and undetermined deaths among adults 55 years and older in 27 states. Participants were all suicides and undetermined deaths (N = 47 759) among persons 55 years and older. Exposure: Long-term care cited in the coroner/medical examiner case narrative, whether as a reason for self-harm or the injury location, identified using machine learning natural language processing (NLP) algorithms plus manual review of texts. Main Outcomes and Measures: Number and characteristics (eg, demographics, health history, and means of injury) of suicides associated with LTC. The κ statistic was used to estimate the reliability of the existing NVDRS injury location codes relative to cases identified by the algorithm. Results: Among 47 759 persons 55 years and older (median age, 64 years; 77.6% male; 90.0% non-Hispanic white), this study identified 1037 suicide deaths associated with LTC, including 428 among older adults living in LTC, 449 among older adults transitioning to LTC, and 160 otherwise associated with LTC. In contrast, there were only 263 cases coded with the existing NVDRS location code "supervised residential facility," which had poor agreement with cases that the algorithm identified as occurring in LTC (κ statistic, 0.30; 95% CI, 0.26-0.35). Conclusions and Relevance: Over a 13-year period, approximately 2.2% of suicides among adults 55 years and older were associated with LTC in some manner. Clinicians, administrators, and policy makers should consider ways to promote the mental health and well-being of older adults experiencing functioning limitations and their families. Natural language processing may be a useful way to improve abstraction of variables in the NVDRS.

Modification of cell vulnerability to oxidative stress by N-(3-oxododecanoyl)-L-homoserine-lactone, a quorum sensing molecule, in rat thymocytes.

N-(3-oxododecanoyl)-l-homoserine-lactone (ODHL), a quorum sensing molecule, affects intracellular Zn2+ concentration ([Zn2+]i) and cellular levels of nonprotein thiols ([NPT]i) of rat thymic lymphocytes, both of which are assumed to affect cell vulnerability to oxidative stress. Therefore, it is interesting to examine the effects of ODHL on the cells under oxidative stress. ODHL augmented the cytotoxicity of H2O2, but not calcium ionophore A23187. ODHL potentiated the H2O2-induced elevation of [Zn2+]i, wherein, it greatly attenuated the H2O2-induced increase in intracellular Ca2+ concentration. ODHL did not affect [NPT]i in the presence of H2O2. Therefore, we conclude that the elevation of [Zn2+]i is involved in the ODHL-induced potentiation of H2O2 cytotoxicity. Our findings suggest that ODHL modifies cell vulnerability to oxidative stress in host cells.

Personal Control Over Decisions to Participate in Research by Persons With Histories of Both Substance Use Disorders and Criminal Justice Supervision.

Individuals must feel free to exert personal control over decisions regarding research participation. We present an examination of participants' perceived personal control over, as well as reported pressures and threats from others, influencing their decision to join a study assessing the effectiveness of extended-release naltrexone in preventing opioid dependence relapse. Most participants endorsed a strong sense of control over the decision; few reported pressures or threats. Although few in number, participants' brief narrative descriptions of the pressures and threats are illuminating and provide context for their perceptions of personal control. Based on this work, we propose a useful set of tools to help ascertain participants' sense of personal control in joining research.

Ziram, a dithiocarbamate fungicide, exhibits pseudo-cytoprotective actions against oxidative stress in rat thymocytes: Possible environmental risks.

Ziram, a dithiocarbamate fungicide, protects various vegetables and fruits against infections by fungus. Recently, there have been increasing anxieties about the risks in the use of dithiocarbamate fungicides. Our previous studies showed that Zn2+ was a determinant of Ziram cytotoxicity. In addition, Zn2+ is linked to H2O2 cytotoxicity. Therefore, in this study, we aimed to test the hypothesis that Ziram could augment the cytotoxicity of H2O2 by examining the changes induced by Ziram in some cellular parameters in rat thymic lymphocytes subjected to H2O2-induced oxidative stress using flow-cytometric methods with fluorescent dyes. Ziram significantly attenuated H2O2-induced cell death at sublethal concentrations. However, in the cells under oxidative stress elicited by H2O2, Ziram promoted the changing over from intact cells to living cells with exposed phosphatidylserine (PS) on plasma membranes, whereas it inhibited the transition from PS-exposed living cells to dead cells. Ziram significantly augmented H2O2 actions, including reduction of cellular glutathione levels and elevation of intracellular Zn2+ concentrations. Conversely, it attenuated H2O2-induced depolarization of mitochondrial membrane potential. Ziram at sublethal concentrations seems to exhibit promotive and suppressive actions on the process of cell death caused by H2O2. Ziram increased the number of living cells with exposed PS, a phenomenon characteristic of early stages of apoptosis. Thus, it is concluded that Ziram exhibits pseudo-cytoprotective actions against H2O2-induced oxidative stress. Ziram at sublethal concentrations exerts promotive and suppressive actions on the process of cell death caused by oxidative stress.

Assessing informed consent in an opioid relapse prevention study with adults under current or recent criminal justice supervision.

Concerns persist that individuals with substance use disorders who are under community criminal justice supervision experience circumstances that might compromise their provision of valid, informed consent for research participation. These concerns include the possibilities that desire to obtain access to treatment might lead individuals to ignore important information about research participation, including information about risks, or that cognitive impairment associated with substance use might interfere with attending to important information. We report results from a consent quiz (CQ) administered in a multisite randomized clinical trial of long-acting naltrexone to prevent relapse to opioid use disorder among adults under community criminal justice supervision-a treatment option difficult to access by this population of individuals. Participants were required to answer all 11 items correctly before randomization. On average, participants answered 9.8 items correctly (89%) at baseline first attempt (n=306). At week 21 (n=212), participants scored 87% (9.5 items correct) without review. Performance was equivalent to, or better than, published results from other populations on a basic consent quiz instrument across multiple content domains. The consent quiz is an efficient method to screen for adequate knowledge of consent information as part of the informed consent process. Clinical researchers who are concerned about these issues should consider using a consent quiz with corrected feedback to enhance the informed consent process. Overall, while primarily useful as an educational tool, employing a CQ as part of the gateway to participation in research may be particularly important as the field continues to advance and tests novel experimental treatments with significant risks and uncertain potential for benefit.

Zinc is a determinant of the cytotoxicity of Ziram, a dithiocarbamate fungicide, in rat thymic lymphocytes: possible environmental risks.

Ziram, one of the dithiocarbamate fungicides, is widely applied to agriculture because this agent protects various crops from fungal infections. Risks of dithiocarbamate biocide use are of concern. It was previously reported that Ziram increased the intracellular concentration of Zn2+. Therefore, we cytometrically studied the mechanism of Zn2+-dependent lethal actions of Ziram on rat lymphocytes at environmentally relevant Zn2+ levels. Membrane and cellular parameters of rat lymphocytes were estimated by flow-cytometric techniques with appropriate fluorescent probes. The Ziram-induced increase in cell lethality was completely attenuated by Zn2+ chelators. A significant increase of cell lethality was found on the simultaneous application of Ziram at a sublethal concentration and ZnCl2. The combination of Ziram and ZnCl2 increased the cellular superoxide anion content and decreased the cellular GSH content, which possibly caused the increase in cell lethality. The zinc concentrations under the present experimental conditions were comparable to the environmentally relevant concentrations found in rivers. Therefore, the environmental level of zinc may be critical in estimating the toxicity of Ziram to wild animals.

Dithiocarbamate fungicides increase intracellular Zn(2+) levels by increasing influx of Zn(2+) in rat thymic lymphocytes.

Dithiocarbamate fungicides are used as alternative antifouling agents to highly toxic organotin antifouling agents, such as tri-n-butyltin and triphenyltin. There are some concerns regarding their environmental and health risks. It has been shown that tri-n-butyltin increases intracellular Zn(2+) levels of mammalian lymphocytes. Therefore, we examined the effects of dithiocarbamate fungicides (Ziram, Thiram, and Zineb) on rat thymic lymphocytes using a flow-cytometric technique to elucidate how these fungicides affect intracellular Zn(2+) levels. We further determined whether the agents increase intracellular Zn(2+) and/or Ca(2+), because both Zn(2+) and Ca(2+) are intracellular signals in lymphocytes, and excessive increases in their intracellular concentrations can have adverse effects. Dithiocarbamate fungicides increased intracellular Zn(2+) levels, without affecting intracellular Ca(2+) levels. Ziram was the most potent compound, increasing intracellular Zn(2+) levels via Zn(2+) influx. Ziram (1µM) greatly decreased the cellular nonprotein thiol content, and Zn(2+) chelators attenuated the Ziram-induced decrease. Ziram increased the population of annexin V-positive cells in a Zn(2+)-dependent manner. Therefore, we propose that dithiocarbamate fungicides induce Zn(2+) influx, resulting in an excessive elevation of intracellular Zn(2+) levels, leading to the induction of apoptosis. This study gives a basic insight into the mechanisms of dithiocarbamate fungicide-induced adverse events.

Clioquinol-induced increase and decrease in the intracellular Zn2+ level in rat thymocytes.

AIMS: Clioquinol is emerging as a potential therapy for some diseases, such as Alzheimer disease and cancer. This agent is a lipophilic chelator of Zn(2+). In this study, the effect of clioquinol on the intracellular Zn(2+) level was examined in order to gain insights into the toxicological profile of clioquinol. MAIN METHODS: The effect of clioquinol was estimated using a flow cytometer and FluoZin-3, a fluorescent indicator for Zn(2+), in rat thymocytes. KEY FINDINGS: Clioquinol, at concentrations ranging from 10 to 300 nM, augmented FluoZin-3 fluorescence in a concentration-dependent manner. However, the effect induced by 1 µM clioquinol was less than that by 300 nM clioquinol. Removal of extracellular Zn(2+), using the membrane impermeable Zn(2+)-chelator diethylenetriamine-N,N,N',N″,N″-pentaacetic acid (DTPA), abolished the clioquinol-induced augmentation of FluoZin-3 fluorescence. Clioquinol did not augment Fluo-3 fluorescence, an indicator of intracellular Ca(2+), in the presence of DTPA. The results suggested that clioquinol caused an extracellular Zn(2+)-dependent increase in the intracellular Zn(2+) concentration. However, in the presence of DTPA, clioquinol at micromolar concentrations (1-10 µM) attenuated FluoZin-3 fluorescence in a concentration-dependent manner. Clioquinol even at 10 µM did not affect FluoZin-3 fluorescence under cell-free condition. The concentration-response relationship for the clioquinol induced change in Zn(2+) level appeared to be bell-shaped. These results indicate that micromolar concentrations of clioquinol, without chelated Zn(2+), decrease intracellular Zn(2+) concentration. SIGNIFICANCE: The effect of clioquinol on the intracellular Zn(2+) level varies, depending on the extracellular Zn(2+) concentration and the clioquinol concentration. Clioquinol may therefore exert various types of Zn(2+)-dependent cytotoxicity.

Nanomolar concentrations of zinc pyrithione increase cell susceptibility to oxidative stress induced by hydrogen peroxide in rat thymocytes.

Zinc pyrithione is used as an antifouling agent. However, the environmental impacts of zinc pyrithione have recently been of concern. Zinc induces diverse actions during oxidative stress; therefore, we examined the effect of zinc pyrithione on rat thymocytes suffering from oxidative stress using appropriate fluorescent probes. The cytotoxicity of zinc pyrithione was not observed when the cells were incubated with 3 µM zinc pyrithione for 3 h. However, zinc pyrithione at nanomolar concentrations (10 nM or more) significantly increased the lethality of cells suffering from oxidative stress induced by 3 mM H(2)O(2). The application of zinc pyrithione alone at nanomolar concentrations increased intracellular Zn(2+) level and the cellular content of superoxide anions, and decreased the cellular content of nonprotein thiols. The simultaneous application of nanomolar zinc pyrithione and micromolar H(2)O(2) synergistically increased the intracellular Zn(2+) level. Therefore, zinc pyrithione at nanomolar concentrations may exert severe cytotoxic action on cells simultaneously exposed to chemicals that induce oxidative stress. If so, zinc pyrithione leaked from antifouling materials into surrounding environments would be a risk factor for aquatic ecosystems. Alternatively, zinc pyrithione under conditions of oxidative stress may become more potent antifouling ingredient.

Putative role of intracellular Zn(2+) release during oxidative stress: a trigger to restore cellular thiol content that is decreased by oxidative stress.

Although the ability of zinc to retard the oxidative process has been recognized for many years, zinc itself has been reported to induce oxidative stress. In order to give some insights into elucidating the role of intracellular Zn(2+) in cells suffering from oxidative stress, the effects of N-ethylmaleimide (NEM) and ZnCl(2) on cellular thiol content and intracellular Zn(2+) concentration were studied by use of 5-chloromethylfluorescein diacetate (5-CMF-DA) and FluoZin-3 pentaacetoxymethyl ester (FluoZin-3-AM) in rat thymocytes. The treatment of cells with NEM attenuated 5-CMF fluorescence and augmented FluoZin-3 fluorescence in a dose-dependent manner. These NEM-induced phenomena were observed under external Zn(2+)-free conditions. Results suggest that NEM decreases cellular thiol content and induces intracellular Zn(2+) release. Micromolar ZnCl(2) dose-dependently augmented both FluoZin-3 and 5-CMF fluorescences, suggesting that the elevation of intracellular Zn(2+) concentration increases cellular thiol content. Taken together, it is hypothesized that intracellular Zn(2+) release during oxidative stress is a trigger to restore cellular thiol content that is decreased by oxidative stress.

Low micromolar zinc exerts cytotoxic action under H2O2-induced oxidative stress: excessive increase in intracellular Zn2+ concentration.

The ability of zinc to retard oxidative processes has been recognized for many years. However, zinc is cytotoxic under certain oxidative stress. In this study, we investigated the effect of H2O2 on intracellular Zn2+ concentration of rat thymocytes and its relation to the cytotoxicity. Experiments were cytometrically performed by the use of fluorescent probes, propidium iodide, FluoZin-3-AM, and 5-chloromethylfluorescein diacetate. ZnCl2 potentiated cytotoxicity of H2O2 while TPEN, a chelator for intracellular Zn2+, attenuated it. Results suggested an involvement of intracellular Zn2+ in the cytotoxicity of H2O2. H2O2 at concentrations of 30microM or more (up to 1000microM) significantly increased intracellular Zn2+ concentration. There were two mechanisms. (1) H2O2 decreased cellular content of nonprotein thiols, possibly resulting in release of Zn2+ from thiols as cellular Zn2+ binding sites. (2) H2O2 increased membrane Zn2+ permeability because external ZnCl2 application further elevated intracellular Zn2+ concentration. Micromolar H2O2 may induce excessive elevation of intracellular Zn2+ concentration that is harmful to cellular functions. However, the incubation with micromolar ZnCl2 alone increased cellular content of nonprotein thiols, one of the factors protecting cells against oxidative stress. Though zinc is generally considered to be protective with its antioxidant property, this study reveals the toxic effect of zinc even in micromolar range under oxidative stress induced by H2O2.

Zinc at clinically-relevant concentrations potentiates the cytotoxicity of polysorbate 80, a non-ionic surfactant.

Polysorbate 80, a non-ionic surfactant, is used in the formula of water-insoluble anticancer agents for intravenous application. In our recent studies, this surfactant decreased cellular thiol content and the chemicals decreasing cellular thiol content increased intracellular Zn(2+) concentration. In this study using rat thymocytes, the effect of polysorbate 80 on FluoZin-3 fluorescence, an indicator for intracellular Zn(2+), and the influence of ZnCl(2) on cytotoxicity of polysorbate 80 were examined in order to test the possibility that Zn(2+) is involved in cytotoxic action of polysorbate 80. The surfactant at concentrations of 10 microg/ml or more significantly augmented FluoZin-3 fluorescent in a concentration-dependent manner, indicating an increase in intracellular Zn(2+) concentration. The increase by polysorbate 80 was also observed after removing extracellular Zn(2+), suggesting an intracellular Zn(2+) release. The simultaneous application of polysorbate 80 (30 microg/ml) and ZnCl(2) (10-30 microM) significantly increased cell lethality. The simultaneous application of ZnCl(2) accelerated the process of cell death induced by polysorbate 80 and the combination increased oxidative stress. Results may indicate that the cytotoxicity of polysorbate 80 at clinical concentrations is modified by micromolar zinc. Although there is no clinical report that polysorbate 80 and zinc salt are simultaneously applied to human as far as our knowledge, it may be speculated that zinc induces some diverse actions in cancer treatment with water-insoluble anticancer agent including nanoparticle drug of which the solvent is polysorbate 80.

Micromolar Zn(2+) potentiates the cytotoxic action of submicromolar econazole in rat thymocytes: possible disturbance of intracellular Ca(2+) and Zn(2+) homeostasis.

Econazole, one of imidazole antifungals, has been reported to exhibit an inhibitory action on Mycobacterium tuberculosis and its multidrug-resistant strains under in vitro and ex vivo conditions. There is a chemotherapeutic potential of econazole against tuberculosis. We have revealed that Zn(2+) at micromolar concentrations potentiates the cytotoxicity of imidazole antifungals by increasing membrane Zn(2+) permeability. It is reminiscent of a possibility that econazole exhibits harmful action on human in the presence of Zn(2+) at a physiological range when the agent is systemically administered. Because it is necessary to characterize the cytotoxic action of econazole in the presence of Zn(2+), we have cytometrically examined the effects of econazole, ZnCl(2), and their combination on rat thymocytes. ZnCl(2) at concentrations ranging from 1 microM to 30 microM significantly increased the lethality induced by 10 microM econazole in a concentration-dependent manner. Econazole at a sublethal concentration of 1 microM significantly augmented the intensity of side scatter in the presence of micromolar ZnCl(2), suggesting the change in an intracellular circumstance by the combination of econazole and ZnCl(2). Econazole at 0.3 microM or more in the presence of ZnCl(2) increased the intensity of Fluo-3 fluorescence, an indicator for intracellular Ca(2+). Furthermore, the intensity of FluoZin-3 fluorescence, an indicator for intracellular Zn(2+), was also augmented by econazole at 0.1 microM or more in the presence of ZnCl(2). Results suggest that the combination of submicromolar econazole with micromolar ZnCl(2) may increase the intracellular concentration of Ca(2+) and Zn(2+), leading to disturbance of intracellular Ca(2+) and Zn(2+) homeostasis that triggers cytotoxic action.

Tri-n-butyltin increases intracellular Zn(2+) concentration by decreasing cellular thiol content in rat thymocytes.

Effect of tri-n-butyltin (TBT), an environmental pollutant, on intracellular Zn(2+) concentration was tested in rat thymocytes to reveal one of cytotoxic profiles of TBT at nanomolar concentrations using a flow cytometer and appropriate fluorescent probes. TBT at concentrations of 30 nM or more (up to 300 nM) significantly increased the intensity of FluoZin-3 fluorescence, an indicator for intracellular Zn(2+) concentration, under external Ca(2+)- and Zn(2+)-free condition. Chelating intracellular Zn(2+) completely attenuated the TBT-induced augmentation of FluoZin-3 fluorescence. Result suggests that nanomolar TBT releases Zn(2+) from intracellular store site. Oxidative stress induced by hydrogen peroxide also increased the FluoZin-3 fluorescence intensity. The effects of TBT and hydrogen peroxide on the fluorescence were additive. TBT-induced changes in the fluorescence of FluoZin-3 and 5-chloromethylfluorescein, an indicator for cellular thiol content, were correlated with a coefficient of -0.962. Result suggests that the intracellular Zn(2+) release by TBT is associated with TBT-induced reduction of cellular thiol content. However, chelating intracellular Zn(2+) potentiated the cytotoxicity of TBT. Therefore, the TBT-induced increase in intracellular Zn(2+) concentration may be a type of stress responses to protect the cells.