Involvement of chemokine receptors in breast cancer metastasis

Breast cancer is characterized by a distinct metastatic pattern involving the regional lymph nodes, bone marrow, lung and liver. Tumour cell migration and metastasis share many similarities with leukocyte trafficking, which is critically regulated by chemokines and their receptors. Here we report that the chemokine receptors CXCR4 and CCR7 are highly expressed in human breast cancer cells, malignant breast tumours and metastases. Their respective ligands CXCL12/SDF-1alpha and CCL21/6Ckine exhibit peak levels of expression in organs representing the first destinations of breast cancer metastasis. In breast cancer cells, signalling through CXCR4 or CCR7 mediates actin polymerization and pseudopodia formation, and subsequently induces chemotactic and invasive responses. In vivo, neutralizing the interactions of CXCL12/CXCR4 significantly impairs metastasis of breast cancer cells to regional lymph nodes and lung. Malignant melanoma, which has a similar metastatic pattern as breast cancer but also a high incidence of skin metastases, shows high expression levels of CCR10 in addition to CXCR4 and CCR7. Our findings indicate that chemokines and their receptors have a critical role in determining the metastatic destination of tumour cells.

A model-based method for assessing insulin sensitivity from the oral glucose tolerance test

OBJECTIVE

Available insulin sensitivity (IS) methods based on the oral glucose tolerance test (OGTT) are empirical. We used a glucose-insulin model to derive an OGTT-based IS (oral glucose insulin sensitivity [OGIS]) index, which predicts glucose clearance in a glucose clamp. We validated OGIS against clamp data.

RESEARCH DESIGN AND METHODS

OGIS requires glucose and insulin concentrations from a 75-g OGTT at 0, 2, and 3 h (3-h OGTT) or at 0, 1.5, and 2 h (2-h OGTT). The formula includes six constants optimized to match the clamp results. For this purpose, 15 lean nondiabetic subjects (BMI < 25 kg/m2), 38 obese nondiabetic subjects (BMI > 25 kg/m2), and 38 subjects with type 2 diabetes randomly underwent an OGTT and a 120 mU x min(-1) x m(-2) insulin infusion euglycemic clamp. Glucose clearance (Cl CLAMP), calculated as the ratio of glucose infusion to concentration during the last hour of the clamp, was compared with OGIS. OGIS was also tested on an independent group of 13 subjects with impaired glucose tolerance (IGT).

RESULTS

OGIS and Cl CLAMP were correlated in the whole group (R = 0.77, P < 0.0001), in the subgroups (lean: R = 0.59; obese: R = 0.73; type 2 diabetes: R = 0.49; P < 0.02), and in the independent IGT group (R = 0.65, P < 0.02). Reproducibility of OGIS and Cl CLAMP were similar (coefficients of variation: OGIS 7.1%, Cl CLAMP 6.4%). OGIS was as effective as Cl CLAMP in discriminating between groups (for OGIS, lean vs. obese: 440 +/- 16 vs. 362 +/- 11 ml x min(-1) x m(-2), p < 0.001; lean vs. type 2 diabetes: 440 +/- 16 vs. 239 +/- 7, P < 0.0001; obese vs. type 2 diabetes: 362 +/- 11 vs. 239 +/- 7, P < 0.0001; results were similar for Cl CLAMP). The relationships between IS and BMI, fasting plasma insulin, and insulin secretion (calculated from the OGTT insulin concentration) were examined. OGIS yielded results similar to Cl CLAMP and fully consistent with established physiological principles. The performance of the index for the 3-h and 2-h OGTT was similar.

CONCLUSIONS

OGIS is an index of IS in good agreement with the clamp. Because of its simplicity (only three blood samples required), this method has potential use for clinical investigation including large-scale epidemiological studies.

IGIF does not drive Th1 development but synergizes with IL-12 for interferon-gamma production and activates IRAK and NFkappaB

In these studies, IFN gamma-inducing factor (IGIF), unlike IL-12, did not drive Th1 development in BALB/c or C57BL/6 mice, but like IL-1alpha, potentiated IL-12-driven Th1 development in BALB/c mice. IGIF and IL-12 synergized for IFN gamma production from Th1 cells. Unlike IL-1alpha, IGIF had no effect on Th2 cells. IGIF signaled through IRAK, IL-1 receptor-associated kinase, to induce nuclear translocation of p65/p50 NFkappaB in Th1 cells. IL-1alpha had no effect on proliferation, cytokine production, or NFkappaB activation in Th1 cells but activated NFkappaB and proliferation in Th2 cells. Thus, Th1 and Th2 cells may differ in responsiveness and receptor expression for IL-1 family molecules. IGIF and IL-1alpha may differentially amplify Th1 and Th2 effector responses, respectively.

Transcription profiling-based identification of Staphylococcus aureus genes regulated by the agr and/or sarA loci

The advent of transcription profiling technologies has provided researchers with an unprecedented ability to study biological processes. Accordingly, a custom-made Affymetrix GeneChip, constituting >86% of the Staphylococcus aureus genome, was used to identify open reading frames that are regulated by agr and/or SarA, the two best-studied regulators of the organism's virulence response. RNA extracted from wild-type cells and agr, sarA, and agr sarA mutant cells in the early-, mid-, and late-log and stationary phases of growth was analyzed. Open reading frames with transcription patterns expected of genes either up- or downregulated in an agr- and/or SarA-dependent manner were identified. Oligonucleotide microarray and Northern blot analyses confirmed that the transcription of several known virulence genes, including hla (alpha-toxin) and spa (protein A), is regulated by each effector and provided insights about the regulatory cascades involved in both alpha-hemolysin and protein A expression. Several putative virulence factors were also identified as regulated by agr and/or SarA. In addition, genes that are involved in several biological processes but which are difficult to reconcile as playing a direct role in the organism's pathogenesis also appeared to be regulated by each effector, suggesting that products of both the agr and the sarA locus are more-global transcription regulators than previously realized.

K-ras is an essential gene in the mouse with partial functional overlap with N-ras

Mammalian ras genes are thought to be critical in the regulation of cellular proliferation and differentiation and are mutated in approximately 30% of all human tumors. However, N-ras and H-ras are nonessential for mouse development. To characterize the normal role of K-ras in growth and development, we have mutated it by gene targeting in the mouse. On an inbred genetic background, embryos homozygous for this mutation die between 12 and 14 days of gestation, with fetal liver defects and evidence of anemia. Thus, K-ras is the only member of the ras gene family essential for mouse embryogenesis. We have also investigated the effect of multiple mutations within the ras gene family. Most animals lacking N-ras function and heterozygous for the K-ras mutation exhibit abnormal hematopoietic development and die between days 10 and 12 of embryogenesis. Thus, partial functional overlap appears to occur within the ras gene family, but K-ras provides a unique and essential function.

A fluorescent indicator for measuring cytosolic free magnesium

The previously developed chelator O-aminophenol-N,N,O-triacetic acid (APTRA) (L. A. Levy, E. Murphy, B. Raju, and R. E. London. Biochemistry 27: 4041-4048, 1988) has been modified to yield a fluorescent analogue which can be utilized as an intracellular probe for ionized Mg2+. The fluorescent analogue, FURAPTRA, with a magnesium dissociation constant of 1.5 mM, is structurally analogous to the calcium chelator fura-2 and exhibits a similar excitation shift on magnesium complexation. Hence, data on the intracellular Mg2+ concentration can be obtained using an analogous ratio method. The acetoxymethyl form of the chelator is readily loaded into cells and has been used to determine a cytosolic free Mg2+ concentration of 0.59 mM for isolated rat hepatocytes. As a consequence of the relatively high levels of cytosolic Mg2+, the problem of ion buffering is much less severe than for the analogous calcium indicators.

Mental Health and Behavior of College Students During the Early Phases of the COVID-19 Pandemic: Longitudinal Smartphone and Ecological Momentary Assessment Study

BACKGROUND

The vast majority of people worldwide have been impacted by coronavirus disease (COVID-19). In addition to the millions of individuals who have been infected with the disease, billions of individuals have been asked or required by local and national governments to change their behavioral patterns. Previous research on epidemics or traumatic events suggests that this can lead to profound behavioral and mental health changes; however, researchers are rarely able to track these changes with frequent, near-real-time sampling or compare their findings to previous years of data for the same individuals.

OBJECTIVE

By combining mobile phone sensing and self-reported mental health data among college students who have been participating in a longitudinal study for the past 2 years, we sought to answer two overarching questions. First, have the behaviors and mental health of the participants changed in response to the COVID-19 pandemic compared to previous time periods? Second, are these behavior and mental health changes associated with the relative news coverage of COVID-19 in the US media?

METHODS

Behaviors such as the number of locations visited, distance traveled, duration of phone usage, number of phone unlocks, sleep duration, and sedentary time were measured using the StudentLife smartphone sensing app. Depression and anxiety were assessed using weekly self-reported ecological momentary assessments of the Patient Health Questionnaire-4. The participants were 217 undergraduate students, with 178 (82.0%) students providing data during the Winter 2020 term. Differences in behaviors and self-reported mental health collected during the Winter 2020 term compared to previous terms in the same cohort were modeled using mixed linear models.

RESULTS

During the first academic term impacted by COVID-19 (Winter 2020), individuals were more sedentary and reported increased anxiety and depression symptoms (P<.001) relative to previous academic terms and subsequent academic breaks. Interactions between the Winter 2020 term and the week of the academic term (linear and quadratic) were significant. In a mixed linear model, phone usage, number of locations visited, and week of the term were strongly associated with increased amount of COVID-19-related news. When mental health metrics (eg, depression and anxiety) were added to the previous measures (week of term, number of locations visited, and phone usage), both anxiety (P<.001) and depression (P=.03) were significantly associated with COVID-19-related news.

CONCLUSIONS

Compared with prior academic terms, individuals in the Winter 2020 term were more sedentary, anxious, and depressed. A wide variety of behaviors, including increased phone usage, decreased physical activity, and fewer locations visited, were associated with fluctuations in COVID-19 news reporting. While this large-scale shift in mental health and behavior is unsurprising, its characterization is particularly important to help guide the development of methods to reduce the impact of future catastrophic events on the mental health of the population.

Reversibility of T helper 1 and 2 populations is lost after long-term stimulation

Commitment of T helper 1 (Th1) or Th2 populations developing during an immune response to a pathogen, or an inappropriate immune response to an allergen or autoantigen, may determine the difference between health and chronic disease. We show that strongly polarized Th1 and Th2 populations assessed by immunoassay are heterogeneous using flow cytometry to detect single cells producing interferon gamma (IFN-gamma) and interleukin 4 (IL-4). Th1 populations arising after 1 wk of stimulation in IL-12 plus anti-IL-4 antibodies could convert to Th2 cells when restimulated in IL-4. Th2 populations resulting from stimulation for 1 wk in IL-4 could give rise to Th1 cells upon restimulation in IL-12 plus anti-IL-4. In contrast, the cytokine profiles of long-term Th1 and Th2 populations arising originally from repeated stimulation in IL-12 or IL-4 appeared more homogeneous and were not reversible, although IL-4 dramatically reduced the number of IFN-gamma-producing Th1 cells. This may explain previous reports that Th1 cells can be converted to Th2 cells.

Elevation in cytosolic free calcium concentration early in myocardial ischemia in perfused rat heart

Changes in cytosolic free calcium concentration during myocardial ischemia were measured by 19F NMR in 5FBAPTA-loaded perfused rat hearts. The hearts were perfused with Krebs-Henseleit buffer containing 5 microM of the acetoxymethyl ester of 5FBAPTA, which was hydrolyzed by cytosolic esterases to achieve cytosolic concentrations of 5FBAPTA of 0.12 to 0.65 mM. Cytosolic free calcium concentrations were calculated as the product of the ratio of peak areas for bound and free 5FBAPTA in the NMR spectra and the dissociation constant (708 nM). The basal cytosolic calcium concentration, measured in potassium or magnesium arrested hearts, was 252 nM, and the time-average calcium concentration in beating hearts was 630 nM. Following the onset of total ischemia, there was no immediate substantial change in cytosolic calcium despite a rapid decline in creatine phosphate and ATP and a marked increase in inorganic phosphate as monitored by 31P NMR, but by 10 minutes, there was a substantial increase in free calcium concentration. The ratio of peak areas of bound and free 5FBAPTA returned to the preischemic value during reperfusion, and there was no detectable loss of 5FBAPTA from the heart. Creatine phosphate was also restored to its preischemic level during reperfusion. These results indicate that cytosolic free calcium increases during ischemia and is not immediately associated with lethal injury. This increase in cytosolic calcium may activate degradative enzymes that eventually could compromise myocyte viability.

The prognosis of depression in old age

The paper describes a one year prospective study of 124 elderly depressed patients. Only one third of the group had a good outcome. Poor outcome was associated with severity of initial illness, those with depressive delusions having a particularly poor outcome. Outcome was also influenced by physical health problems and severe life events in the follow-up year. Social class differences in outcome were thought to be due to class differences in the experience of severe life events. There was no evidence that an intimate relationship protected against relapse in the face of continuing life stress.

Genome-wide transcriptional profiling of the response of Staphylococcus aureus to cell-wall-active antibiotics reveals a cell-wall-stress stimulon

The molecular events following inhibition of bacterial peptidoglycan synthesis have not been studied extensively. Previous proteomic studies have revealed that certain proteins are produced in increased amounts upon challenge of Staphylococcus aureus with cell-wall-active antibiotics. In an effort to further those studies, the genes upregulated in their expression in response to cell-wall-active antibiotics have been identified by genome-wide transcriptional profiling using custom-made Affymetrix S. aureus GeneChips. A large number of genes, including ones encoding proteins involved in cell-wall metabolism (including pbpB, murZ, fmt and vraS) and stress responses (including msrA, htrA, psrA and hslO), were upregulated by oxacillin, D-cycloserine or bacitracin. This response may represent the transcriptional signature of a cell-wall stimulon induced in response to cell-wall-active agents. The findings imply that treatment with cell-wall-active antibiotics results in damage to proteins including oxidative damage. Additional genes in a variety of functional categories were upregulated uniquely by each of the three cell-wall-active antibiotics studied. These changes in gene expression can be viewed as an attempt by the organism to defend itself against the antibacterial activities of the agents.

Diazoxide-induced cardioprotection requires signaling through a redox-sensitive mechanism

Diazoxide, a selective opener of the mitochondrial ATP-sensitive potassium channel, has been shown to elicit tolerance to ischemia in cardiac myocytes and in perfused heart. However, the mechanism of this cardioprotection is poorly understood. Because reactive oxygen species (ROS) are recognized as important intracellular signaling molecules and have been implicated in ischemic preconditioning, we examined diazoxide-induced ROS production in adult cardiomyocytes. Cells treated with 50 micromol/L diazoxide showed a 173% increase in ROS production relative to baseline. 5-Hydroxydecanoate was found to attenuate the diazoxide-induced increase in ROS generation. The diazoxide-induced increase in ROS also was abrogated by the addition of either the antioxidant N-acetylcysteine (NAC) or N-mercaptopropionylglycine. We also examined the ability of NAC to block the protective effects of diazoxide in the perfused rat heart. After 20 minutes of global ischemia and 20 minutes of reflow, hearts perfused with 100 micromol/L diazoxide before ischemia showed significantly improved postischemic contractile function relative to untreated hearts (84% versus 29% of initial left ventricular developed pressure, respectively). Hearts treated with diazoxide in the presence of 4 mmol/L NAC recovered 53% of initial left ventricular developed pressure, whereas hearts treated with NAC alone recovered 46% of preischemic function. Using (31)P NMR spectroscopy, we found that, similar to preconditioning, diazoxide significantly attenuated ischemia-induced intracellular acidification and enhanced post- ischemic recovery of phosphocreatine levels, both of which were blocked by cotreatment with NAC. These data suggest that the cardioprotective actions of diazoxide are mediated by generation of a pro-oxidant environment.

Screening for multiple sclerosis cognitive impairment using a self-administered 15-item questionnaire

Since there is a need for cost-effective screening techniques to identify neuropsychological impairment in multiple sclerosis (MS) patients, and because existing methods require cognitive testing with subsequent interpretation by a neuropsychologist, a brief self-report procedure was developed to screen for neuropsychological impairment in MS. In the first phase of the study, a pool of 80 items was generated based on a literature review and consultation with healthcare professionals. The set was reduced to 15 via Rasch analysis. Using these items, a brief (five minute) MS Neuropsychological Screening Questionnaire (MSNQ), including patient- and informant-report forms, was composed. In phase II, 50 MS patients and their caregivers completed the MSNQ. A comprehensive neuropsychological test battery was also administered. Analyses covered the reliability of the MSNQ and correlations between both patient- and informant-report scores and objective neuropsychological testing. Cronbach's alpha coefficients were 0.93 and 0.94 for the patient- and informant-report forms, respectively, and both forms of the test were strongly correlated with a more general cognitive complaints questionnaire. The patient MSNQ form correlated significantly with measures of depression but not with objective tests of cognitive function. In contrast, the informant form was correlated with patient cognitive performance but not depression. A cut-off score of 27 on the informant form of the MSNQ optimally separated patients based on a neuropsychological summary score encompassing measures of processing speed and memory. There were two false-negatives and one false-positive, giving the test a sensitivity of 0.83 and a specificity of 0.97. It is concluded, therefore, that this self-administered neuropsychological screening test is reliable and predicts neuropsychological impairment in MS patients with a reasonable degree of accuracy.

Ischemic preconditioning activates phosphatidylinositol-3-kinase upstream of protein kinase C

The present study is designed to test whether phosphatidylinositol 3-kinase (PI3-kinase) has a role in the signaling pathway in ischemic preconditioning (PC) and whether it is proximal or distal to protein kinase C (PKC). Before 20 minutes of global ischemia, Langendorff-perfused rat hearts were perfused for 20 minutes (control); preconditioned with 4 cycles of 5-minute ischemia and 5-minute reflow (PC); treated with either wortmannin (WM) or LY 294002 (LY), each of which is a PI3-kinase inhibitor, for 5 minutes before and throughout PC; treated with 1,2-dioctanoyl-sn-glycerol (DOG), an activator of PKC for 10 minutes (DOG); treated identically to the DOG group except with WM added 10 minutes before and during perfusion with DOG; or treated with either WM or LY for 25 minutes. Recovery of left ventricular developed pressure (LVDP; percentage of initial preischemic LVDP), measured after 30 minutes of reflow, was improved by PC (72+/-2% versus 36+/-4% in control; P<0.001), and this was blocked by WM and LY (41+/-4% and 43+/-5%, respectively; P<0.05 compared with PC). DOG addition improved postischemic LVDP (67+/-6%; P<0.001 compared with control), but in contrast to its effect on PC, WM did not completely eliminate the protective effect of DOG (52+/-4%; P>0.05 compared with DOG; P<0.05 compared with control). PC induced phosphorylation of protein kinase B and translocation of PKC epsilon, and it increased NO production, and these effects were blocked by WM, which suggests a role for PI3-kinase in PC upstream of PKC and NO.

Correlation between cytosolic free calcium, contracture, ATP, and irreversible ischemic injury in perfused rat heart

The relations between ATP depletion, increased cytosolic free calcium concentration [( Cai]), contracture development, and lethal myocardial ischemic injury, as evaluated by enzyme release, were examined using 19F nuclear magnetic resonance to measure [Cai] in 1,2-bis(2-amino-5-fluorophenoxy)ethane-N,N,N',N'-tetraacetic acid (5F-BAPTA)-loaded perfused rat hearts. Total ischemia at 37 degrees C was induced in beating hearts, potassium-arrested hearts, magnesium-arrested hearts, and hearts pretreated with 0.9 microM diltiazem to reduce but not abolish contractility. In the beating hearts, time-averaged [Cai], which is intermediate between the systolic and the basal [Cai], was 544 +/- 74 nM. In contrast, in the potassium- and magnesium-arrested hearts, the time-averaged values are lower than in beating hearts (352 +/- 88 nM for potassium arrest, 143 +/- 22 nM for magnesium arrest). During ischemia, ATP depletion, contracture, and a rise in [Cai] are delayed by cardiac arrest, but all occur more rapidly in the potassium-arrested hearts than in the magnesium-arrested hearts. The diltiazem-treated hearts were generally similar to the magnesium-arrested hearts in their response to ischemia. Under all conditions, contracture development was initiated after tissue ATP had fallen to less than 50% of control; invariably, there was a progressive rise in [Cai] during and following contracture development. Reperfusion with oxygenated perfusate shortly after peak contracture development resulted in a return of [Cai] to its preischemic level, resynthesis of creatine phosphate, no significant enzyme release, and no substantial loss of 5F-BAPTA from the heart. The data demonstrate that an increase in [Cai] precedes lethal myocardial ischemic injury. This rise in [Cai] may accelerate the depletion of cellular ATP and may directly contribute to the development of lethal ischemic cell injury.

Global regulation of Staphylococcus aureus genes by Rot

Staphylococcus aureus produces a wide array of cell surface and extracellular proteins involved in virulence. Expression of these virulence factors is tightly controlled by numerous regulatory loci, including agr, sar, sigB, sae, and arl, as well as by a number of proteins with homology to SarA. Rot (repressor of toxins), a SarA homologue, was previously identified in a library of transposon-induced mutants created in an agr-negative strain by screening for restored protease and alpha-toxin. To date, all of the SarA homologues have been shown to act as global regulators of virulence genes. Therefore, we investigated the extent of transcriptional regulation of staphylococcal genes by Rot. We compared the transcriptional profile of a rot agr double mutant to that of its agr parental strain by using custom-made Affymetrix GeneChips. Our findings indicate that Rot is not only a repressor but a global regulator with both positive and negative effects on the expression of S. aureus genes. Our data also indicate that Rot and agr have opposing effects on select target genes. These results provide further insight into the role of Rot in the regulatory cascade of S. aureus virulence gene expression.

Mechanism of preconditioning. Ionic alterations

The mechanism by which preconditioning (brief intermittent periods of ischemia and reflow) improves recovery of function and reduces enzyme release after a subsequent 30-minute period of ischemia was investigated in perfused rat hearts. Specifically, it was hypothesized that ischemia after preconditioning would result in a decreased production of H+ and therefore a smaller rise in [Na+]i and [Ca2+]i via Na(+)-H+ and Na(+)-Ca2+ exchange. To test this hypothesis we measured pHi, [Na+]i, [Ca2+]i, and cell high-energy phosphates during ischemia and reflow, and we correlated this with recovery of contractile function and release of creatine kinase during reflow. 31P nuclear magnetic resonance (NMR) was used to measure pHi and cell phosphates. [Na+]i was measured by 23Na NMR using the shift reagent thulium 1,4,7,10-tetraazacyclododecane-N,N,'N",N"'-tetramethylenephosph onate to distinguish intracellular from extracellular sodium. [Ca2+]i was measured by 19F NMR using hearts loaded with 1,2-bis(2-amino-5-fluorophenoxy)ethane-N,N,N',N'-tetraacetic acid, termed 5F-BAPTA. Basal time-averaged levels of pHi, [Na+]i, and [Ca2+]i were 7.07 +/- 0.08, 9.4 +/- 0.8 mM, and 715 +/- 31 nM, respectively. After 30 minutes of ischemia, in preconditioned hearts, pHi was 6.5 +/- 0.06, [Na+]i was 2.09 +/- 4.4 mM, [Ca2+]i was 2.1 +/- 0.4 microM, and ATP was negligible. In untreated hearts, after 30 minutes of ischemia, pHi was 6.3 +/- 0.08, [Na+]i was 26.7 +/- 3.8 mM, [Ca2+]i was 3.2 +/- 0.6 microM, and ATP was undetectable. During reperfusion after 30 minutes of ischemia, preconditioned hearts had significantly better recovery of contractile function than untreated hearts (71 +/- 9% versus 36 +/- 8% initial left ventricular developed pressure), and after 60 minutes of ischemia, preconditioned hearts had significantly less release of the intracellular enzyme creatine kinase (102 +/- 12 versus 164 +/- 17 IU/g dry wt). We also found that unpreconditioned hearts arrested with 16 mM MgCl2 (to inhibit calcium entry via calcium channels and Na(+)-Ca2+ exchange) before 30 minutes of ischemia recover function on reflow to the same extent as preconditioned hearts with or without magnesium arrest. Thus, preconditioning has no additional benefit in addition to magnesium arrest. In addition, in hearts that received 16 mM MgCl2 just before the 30-minute period of ischemia, preconditioning had no effect on the rise in [Ca2+]i during the 30-minute period of ischemia. These data support the hypothesis that preconditioning attenuates the increase in [Ca2+]i, [Na+]i, and [H+]i during ischemia, most likely because of reduced stimulation of Na(+)-H+ and Na(+)-Ca2+ exchange.(ABSTRACT TRUNCATED AT 400 WORDS)

Social origins of depression in old age

In a comparison between elderly depressed subjects and normal elderly people in the general population, an association was found between severe life events, major social difficulties, poor physical health and the onset of depression. Working class subjects within the general population had a higher incidence of depression and this appeared to be explained by their poorer health and greater social difficulties. Those elderly people who lacked a confiding relationship were more vulnerable to depression. Evidence is presented that the lack of a confidant was a reflection of life-long personality traits.

Natural history of "high-risk" bundle-branch block: final report of a prospective study

We conducted a prospective study in which 554 patients with chronic bifascicular and trifascicular conduction abnormalities were followed for an average of 42.4 +/- 8.5 months. Heart block occurred in 19 patients, and 17 were successfully treated. The actuarial five-year mortality from an event that could conceivably have been a bradyarrhythmia was 6 per cent (35 per cent from all causes). Of the 160 deaths 67 (42 per cent) were sudden; most of these were not ascribable to bradyarrhythmia but to tachyarrhythmia and myocardial infarction. Mortality was higher in patients with coronary-artery disease (P less than 0.01) and congestive heart failure (P less than 0.05). Patients in whom syncope developed before or after entry into the study had a 17 per cent incidence of heart block (2 per cent in those without syncope)(P less than 0.05); however, no single variable was predictive of which patients were at high risk of death from a bradyarrhythmia. The predictors of death were increasing age, congestive heart failure, and coronary-artery disease; the predictors of sudden death were coronary-artery disease and increasing age. The risks of heart block and of death from a bradyarrhythmia are low; in most patients, heart block can be recognized and successfully treated with a pacemaker.

Amiloride delays the ischemia-induced rise in cytosolic free calcium

An increase in cytosolic free calcium (Cai) has been shown to occur early during ischemia in perfused rat, ferret, and rabbit hearts. It has been proposed that this increase in Cai may occur as a result of exchange of Nai for Cao, which occurs as a result of an increase in Nai arising from exchange of Nao for H+i. The latter exchange is stimulated by the intracellular acidification that occurs during ischemia. To test this hypothesis, we examined Cai, Nai, ATP, and pHi during ischemia in rats in the presence and absence of 1 mM amiloride, a Na-H exchange inhibitor. Cai was measured using 19F nuclear magnetic resonance (NMR) of 1,2-bis(2-amino-5-fluorophenoxy)ethane-N,N,N',N'-tetra-acetic acid (5F-BAPTA)-loaded rat hearts. Nai was measured using 23Na NMR, and the shift reagent 1,4,7,10-tetraazacyclododecane-N,N',N",N"'-tetramethylenephosph onate (Tm[DOTP]-5) was used to separate Nai and Nao. ATP and pH were determined from 31P NMR measurements. During 20 minutes of ischemia, amiloride did not significantly alter the ATP decline but did significantly attenuate the rise in Nai and Cai. After 20 minutes of ischemia, time-averaged Cai was 1.0 +/- 0.2 microM (mean +/- SEM) in amiloride-treated hearts compared with 2.3 +/- 0.9 microM in nontreated hearts. After 20 minutes of ischemia, Nai in the untreated heart was threefold greater than control, whereas in the amiloride-treated heart, Nai was not significantly different from control. These data are consistent with the involvement of Na-Ca exchange in the rise in Cai during ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Molecular cloning, expression, and functional significance of a cytochrome P450 highly expressed in rat heart myocytes

A cDNA encoding a P450 monooxygenase was amplified from reverse transcribed rat heart and liver total RNA by polymerase chain reaction using primers based on the 5'- and 3'-end sequences of two rat pseudogenes, CYP2J3P1 and CYP2J3P2. Sequence analysis revealed that this 1,778-base pair cDNA contained an open reading frame and encoded a new 502 amino acid protein designated CYP2J3. Based on the deduced amino acid sequence, CYP2J3 was approximately 70% homologous to both human CYP2J2 and rabbit CYP2J1. Recombinant CYP2J3 protein was co-expressed with NADPH-cytochrome P450 oxidoreductase in Sf9 insect cells using a baculovirus expression system. Microsomal fractions of CYP2J3/NADPH-cytochrome P450 oxidoreductase-transfected cells metabolized arachidonic acid to 14,15-, 11,12-, and 8, 9-epoxyeicosatrienoic acids and 19-hydroxyeicosatetraenoic acid as the principal reaction products (catalytic turnover, 0.2 nmol of product/nmol of cytochrome P450/min at 37 degrees C). Immunoblotting of microsomal fractions prepared from rat tissues using a polyclonal antibody raised against recombinant CYP2J2 that cross-reacted with CYP2J3 but not with other known rat P450s demonstrated abundant expression of CYP2J3 protein in heart and liver. Immunohistochemical staining of formalin-fixed paraffin-embedded rat heart tissue sections using the anti-CYP2J2 IgG and avidin-biotin-peroxidase detection localized expression of CYP2J3 primarily to atrial and ventricular myocytes. In an isolated-perfused rat heart model, 20 min of global ischemia followed by 40 min of reflow resulted in recovery of only 44 +/- 6% of base-line contractile function. The addition of 5 microM 11, 12-epoxyeicosatrienoic acid to the perfusate prior to global ischemia resulted in a significant 1.6-fold improvement in recovery of cardiac contractility (69 +/- 5% of base line, p = 0.01 versus vehicle alone). Importantly, neither 14,15-epoxyeicosatrienoic acid nor 19-hydroxyeicosatetraenoic acid significantly improved functional recovery following global ischemia, demonstrating the specificity of the biological effect for the 11, 12-epoxyeicosatrienoic acid regioisomer. Based on these data, we conclude that (a) CYP2J3 is one of the predominant enzymes responsible for the oxidation of endogenous arachidonic acid pools in rat heart myocytes and (b) 11,12-epoxyeicosatrienoic acid may play an important functional role in the response of the heart to ischemia.

The dose-effect relationships between torture and psychiatric symptoms in Vietnamese ex-political detainees and a comparison group

The purpose of this study was to determine in Vietnamese ex-political detainees newly arrived into the United States a) the prevalence of torture and psychiatric symptoms and b) the dose-effect relationships between cumulative torture experience and the psychiatric symptoms of posttraumatic stress disorder (PTSD) and major depression. The study population included Vietnamese ex-political detainees (N = 51) and a comparison group (N = 22). All respondents received culturally validated instruments with known psychometric properties including Vietnamese versions of the Hopkins Symptom Checklist-25 and the Harvard Trauma Questionnaire. The ex-political detainees, in contrast to the comparison group, had experienced more torture events (12.2 SD = 4.2 vs. 2.6 SD = 3.1) and had higher rates of PTSD (90% vs. 79%) and depression (49% vs. 15%). Dose-effect relationships between cumulative torture experience and psychiatric symptoms were positive with the PTSD subcategory of "increased arousal" revealing the strongest association. These findings provide evidence that torture is associated with psychiatric morbidity in Vietnamese refugees. The demonstration of significant dose-effect responses supports the hypothesis that torture is a major risk factor in the etiology of major depression and PTSD. The generalizability of these results to other torture survivor groups is unknown. The interaction between torture and other pre- and post-migration risk factors over time in different cultural settings still needs to be examined.

Effects of changes in body weight on carbohydrate metabolism, catecholamine excretion, and thyroid function

BACKGROUND

Weight gain and loss increases and decreases energy expenditure, respectively, out of proportion to changes in metabolic mass.

OBJECTIVE

We hypothesized that changes in energy expenditure associated with weight gain or loss were due in part to changes in catecholamine release, thyroid hormones, carbohydrate utilization, or a combination thereof.

METHODS

Urinary catecholamine excretion, serum thyroid hormone concentrations, and results of 3-h oral-glucose-tolerance tests were examined in obese and never-obese subjects at their usual weights, during weight loss or gain, and at stable weights 10-20% below or 10% above usual.

RESULTS

Urinary norepinephrine excretion decreased significantly during and after weight loss and increased during and after weight gain. Serum concentrations of reverse triiodothyronine increased significantly during and after weight loss, whereas serum concentrations of triiodothyronine increased significantly (by approximately 0%) during and after weight gain. Serum insulin and glucose concentrations during the oral-glucose-tolerance test increased significantly after weight gain in obese subjects. The percentage change in urinary norepinephrine excretion and in serum concentrations of triiodothyronine were significantly correlated with percentage changes in energy expenditure and with each other.

CONCLUSIONS

Changes in body weight were associated with changes in catecholamine excretion and thyroid hormones, which might-by virtue of the effects on energy expenditure-have favored a return to usual body weight. Weight gain induced more apparent insulin resistance in the obese than the never-obese subjects, suggesting a threshold effect of total body fat on this phenomenon.