Sodium reduction for hypertension prevention in overweight adults: further results from the Trials of Hypertension Prevention Phase II

Sodium reduction is efficacious for primary prevention of hypertension, but the feasibility of achieving this effect is unclear. The objective of the paper is detailed analyses of adherence to and effects of the sodium reduction intervention among overweight adults in the Trials of Hypertension Prevention, Phase II. Sodium reduction (comprehensive education and counselling about how to reduce sodium intake) was tested vs no dietary intervention (usual care) for 36-48 months. A total of 956 white and 203 black adults, ages 30-54 years, with diastolic blood pressure 83-89 mmHg, systolic blood pressure (SBP) <140 mmHg, and body weight 110-165% of gender-specific standard weight were included in the study. At 36 months, urinary sodium excretion was 40.4 mmol/24 h (24.4%) lower in sodium reduction compared to usual care participants (P<0.0001), but only 21% of sodium reduction participants achieved the targeted level of sodium excretion below 80 mmol/24 h. Adherence was positively related to attendance at face-to-face contacts. Net decreases in SBP at 6, 18, and 36 months of 2.9 (P<0.001), 2.0 (P<0.001), and 1.3 (P=0.02) mmHg in sodium reduction vs usual care were associated with an overall 18% lower incidence of hypertension (P=0.048); were relatively unchanged by adjustment for ethnicity, gender, age, and baseline blood pressure, BMI, and sodium excretion; and were observed in both black and white men and women. From these beneficial but modest results with highly motivated and extensively counselled individuals, sodium reduction sufficient to favourably influence the population blood pressure distribution will be difficult to achieve without food supply changes.

Efficacy of RTS,S/AS02 malaria vaccine against Plasmodium falciparum infection in semi-immune adult men in The Gambia: a randomised trial

BACKGROUND

RTS,S/AS02 is a pre-erythrocytic malaria vaccine based on the circumsporozoite surface protein of Plasmodium falciparum fused to HBsAg, incorporating a new adjuvant (AS02). We did a randomised trial of the efficacy of RTS,S/AS02 against natural P. falciparum infection in semi-immune adult men in The Gambia.

METHODS

306 men aged 18-45 years were randomly assigned three doses of either RTS,S/AS02 or rabies vaccine (control). Volunteers were given sulfadoxine/pyrimethamine 2 weeks before dose 3, and kept under surveillance throughout the malaria transmission season. Blood smears were collected once a week and whenever a volunteer developed symptoms compatible with malaria. The primary endpoint was time to first infection with P. falciparum. Analysis was per protocol.

FINDINGS

250 men (131 in the RTS,S/AS02 group and 119 in the control group) received three doses of vaccine and were followed up for 15 weeks. RTS,S/AS02 was safe and well tolerated. P. falciparum infections occurred significantly earlier in the control group than the RTS,S/AS02 group (Wilcoxon's test p=0.018). Vaccine efficacy, adjusted for confounders, was 34% (95% CI 8.0-53, p=0.014). Protection seemed to wane: estimated efficacy during the first 9 weeks of follow-up was 71% (46-85), but decreased to 0% (-52 to 34) in the last 6 weeks. Vaccination induced strong antibody responses to circumsporozoite protein and strong T-cell responses. Protection was not limited to the NF54 parasite genotype from which the vaccine was derived. 158 men received a fourth dose the next year and were followed up for 9 weeks; during this time, vaccine efficacy was 47% (4-71, p=0.037).

INTERPRETATION

RTS,S/AS02 is safe, immunogenic, and is the first pre-erythrocytic vaccine to show significant protection against natural P. falciparum infection.

Context processing in older adults: evidence for a theory relating cognitive control to neurobiology in healthy aging

A theory of cognitive aging is presented in which healthy older adults are hypothesized to suffer from disturbances in the processing of context that impair cognitive control function across multiple domains, including attention, inhibition, and working memory. These cognitive disturbances are postulated to be directly related to age-related decline in the function of the dopamine (DA) system in the prefrontal cortex (PFC). A connectionist computational model is described that implements specific mechanisms for the role of DA and PFC in context processing. The behavioral predictions of the model were tested in a large sample of older (N = 81) and young (N = 175) adults performing variants of a simple cognitive control task that placed differential demands on context processing. Older adults exhibited both performance decrements and, counterintuitively, performance improvements that are in close agreement with model predictions.

Anterior cingulate cortex, conflict monitoring, and levels of processing

It has been hypothesized that the anterior cingulate cortex (ACC) contributes to cognition by detecting conflicts that might occur during information processing, to signal the need to engage top-down attentional processes. The present study was designed to investigate which levels of processing are being monitored by the ACC for the presence of conflict. Event-related fMRI was used to measure the response of the ACC during an interference task in which distracting information could be congruent, conflicting at the level of stimulus identification, or conflicting at the response level. Although both types of conflict caused reaction time interference, the fMRI data showed that the ACC is responsive only to response conflict, even when controlling for reaction times. These results suggest a highly specific contribution of the ACC to executive functions, through the detection of conflicts occurring at later or response-related levels of processing.

Sex differences in chest pain in patients with documented coronary artery disease and exercise-induced ischemia: Results from the PIMI study

BACKGROUND

Sex differences in the pathophysiologic course of coronary artery disease (CAD) are widely recognized, yet accurate diagnosis of coronary artery disease in women remains challenging.

METHODS

To determine sex differences in the clinical manifestation of CAD, we studied chest pain reported during daily activities, exercise, and mental stress in 170 men and 26 women. All patients had documented CAD (>50% narrowing in at least 1 major coronary artery or prior myocardial infarction) and all had 1-mm ST-segment depression on treadmill exercise. We collected psychologic test results, serum samples (potassium, epinephrine, norepinephrine, cortisol, b-endorphin, and glucose), and cardiac function, sensory threshold, and autonomic function data at specified times before, during, or after exercise and mental stress tests to assess measures of depression, anxiety, and neurohormonal and thermal pain perception.

RESULTS

Women reported chest pain more often than men during daily activities (P =.04) and during laboratory mental stressors (P =.01) but not during exercise. Men had lower scores than women on measures of depression, trait anxiety, harm avoidance, and reward dependence (P <.05 for all). Women had significantly lower plasma b-endorphin levels at rest (4.2 +/- 3.9 vs 5.0 +/- 2.5 pmol/L for men, P =.005) and at maximal mental stress (6.4 +/- 5.1 vs 7.4 +/- 3.5 pmol/L for men, P <.01). A higher proportion of women than men had marked pain sensitivity to graded heat stimuli applied to skin (hot pain threshold <41 degrees C, 33% vs 10%, P =.001).

CONCLUSIONS

Our results reflect sex differences in the affective and discriminative aspects of pain perception and may help explain sex-related differences in clinical presentations.

An fMRI investigation of emotional engagement in moral judgment

The long-standing rationalist tradition in moral psychology emphasizes the role of reason in moral judgment. A more recent trend places increased emphasis on emotion. Although both reason and emotion are likely to play important roles in moral judgment, relatively little is known about their neural correlates, the nature of their interaction, and the factors that modulate their respective behavioral influences in the context of moral judgment. In two functional magnetic resonance imaging (fMRI) studies using moral dilemmas as probes, we apply the methods of cognitive neuroscience to the study of moral judgment. We argue that moral dilemmas vary systematically in the extent to which they engage emotional processing and that these variations in emotional engagement influence moral judgment. These results may shed light on some puzzling patterns in moral judgment observed by contemporary philosophers.

An integrative theory of prefrontal cortex function

The prefrontal cortex has long been suspected to play an important role in cognitive control, in the ability to orchestrate thought and action in accordance with internal goals. Its neural basis, however, has remained a mystery. Here, we propose that cognitive control stems from the active maintenance of patterns of activity in the prefrontal cortex that represent goals and the means to achieve them. They provide bias signals to other brain structures whose net effect is to guide the flow of activity along neural pathways that establish the proper mappings between inputs, internal states, and outputs needed to perform a given task. We review neurophysiological, neurobiological, neuroimaging, and computational studies that support this theory and discuss its implications as well as further issues to be addressed

Hematologic masquerade of rhabdomyosarcoma

We present the case of a 12-year-old boy admitted with the diagnosis of acute leukemia, but found to have an infiltration of the marrow by an alveolar rhabdomyosarcoma (RMS) as determined by the cytogenetic demonstration of a t(2;13)(q25;q14). A primary tumor could not be found. With this case as a basis, we have tabulated features of all similar cases in the literature and discuss the possible optimal approaches to establishing the correct diagnosis in such patients.

Conflict monitoring and cognitive control

A neglected question regarding cognitive control is how control processes might detect situations calling for their involvement. The authors propose here that the demand for control may be evaluated in part by monitoring for conflicts in information processing. This hypothesis is supported by data concerning the anterior cingulate cortex, a brain area involved in cognitive control, which also appears to respond to the occurrence of conflict. The present article reports two computational modeling studies, serving to articulate the conflict monitoring hypothesis and examine its implications. The first study tests the sufficiency of the hypothesis to account for brain activation data, applying a measure of conflict to existing models of tasks shown to engage the anterior cingulate. The second study implements a feedback loop connecting conflict monitoring to cognitive control, using this to simulate a number of important behavioral phenomena.

Relation of prefrontal cortex dysfunction to working memory and symptoms in schizophrenia

OBJECTIVE

The dorsolateral prefrontal cortex has been implicated in both working memory and the pathophysiology of schizophrenia. A relationship among dorsolateral prefrontal cortex activity, working memory dysfunction, and symptoms in schizophrenia has not been firmly established, partly because of generalized cognitive impairments in patients and task complexity. Using tasks that parametrically manipulated working memory load, the authors tested three hypotheses: 1) patients with schizophrenia differ in prefrontal activity only when behavioral performance differentiates them from healthy comparison subjects, 2) dorsolateral prefrontal cortex dysfunction is associated with poorer task performance, and 3) dorsolateral prefrontal cortex dysfunction is associated with cognitive disorganization but not negative or positive symptoms.

METHOD

Seventeen conventionally medicated patients with schizophrenia and 16 healthy comparison subjects underwent functional magnetic resonance imaging while performing multiple levels of the "n-back" sequential-letter working memory task.

RESULTS

Patients with schizophrenia showed a deficit in physiological activation of the right dorsolateral prefrontal cortex (Brodmann's area 46/9) in the context of normal task-dependent activity in other regions, but only under the condition that distinguished them from comparison subjects on task performance. Patients with greater dorsolateral prefrontal cortex dysfunction performed more poorly. Dorsolateral prefrontal cortex dysfunction was selectively associated with disorganization symptoms.

CONCLUSIONS

These results are consistent with the hypotheses that working memory dysfunction in patients with schizophrenia is caused by a disturbance of the dorsolateral prefrontal cortex and that this disturbance is selectively associated with cognitive disorganization. Further, the pattern of behavioral performance suggests that dorsolateral prefrontal cortex dysfunction does not reflect a deficit in the maintenance of stimulus representations per se but points to deficits in more associative components of working memory.

Conflict monitoring and cognitive control

A neglected question regarding cognitive control is how control processes might detect situations calling for their involvement. The authors propose here that the demand for control may be evaluated in part by monitoring for conflicts in information processing. This hypothesis is supported by data concerning the anterior cingulate cortex, a brain area involved in cognitive control, which also appears to respond to the occurrence of conflict. The present article reports two computational modeling studies, serving to articulate the conflict monitoring hypothesis and examine its implications. The first study tests the sufficiency of the hypothesis to account for brain activation data, applying a measure of conflict to existing models of tasks shown to engage the anterior cingulate. The second study implements a feedback loop connecting conflict monitoring to cognitive control, using this to simulate a number of important behavioral phenomena.

Selective deficits in prefrontal cortex function in medication-naive patients with schizophrenia

BACKGROUND

Previously we proposed that dorsolateral prefrontal cortex (PFC) supports a specific working memory (WM) subcomponent: the ability to represent and maintain context information necessary to guide appropriate task behavior. By context, we mean prior task-relevant information represented in such a form that it supports selection of the appropriate behavioral response. Furthermore, we hypothesized that WM deficits in schizophrenia reflect impaired context processing due to a disturbance in dorsolateral PFC. We use functional magnetic resonance imaging to examine PFC activation in medication-naive, first-episode patients with schizophrenia during a WM, task-isolating context processing.

METHODS

Fourteen first-episode, medication-naive patients with schizophrenia and 12 controls similar in age, sex, and parental education underwent functional magnetic resonance imaging during performance of an A-X version of the Continuous Performance Test.

RESULTS

Patients with schizophrenia demonstrated deficits in dorsolateral PFC activation in task conditions requiring context processing but showed intact activation of posterior and inferior PFC. In addition, patients demonstrated intact activation of the primary motor and somatosensory cortex in response to stimulus processing demands.

CONCLUSIONS

These results demonstrate selectivity in dorsolateral PFC dysfunction among medication-naive first-episode patients with schizophrenia, suggesting that a specific deficit in PFC function is present at illness onset, prior to the administration of medication or the most confounding effects of illness duration. Furthermore, these results are consistent with the hypothesis that WM deficits in patients with schizophrenia reflect an impairment in context processing due to a disturbance in dorsolateral PFC function.

A role for flavin monooxygenase-like enzymes in auxin biosynthesis

Although auxin is known to regulate many processes in plant development and has been studied for over a century, the mechanisms whereby plants produce it have remained elusive. Here we report the characterization of a dominant Arabidopsis mutant, yucca, which contains elevated levels of free auxin. YUCCA encodes a flavin monooxygenase-like enzyme and belongs to a family that includes at least nine other homologous Arabidopsis genes, a subset of which appears to have redundant functions. Results from tryptophan analog feeding experiments and biochemical assays indicate that YUCCA catalyzes hydroxylation of the amino group of tryptamine, a rate-limiting step in tryptophan-dependent auxin biosynthesis.

[Association of Kaposi sarcoma--multiple myeloma. A new case]

INTRODUCTION

Kaposi's disease is an angiogenic multifocal cancer process that has several forms, namely Mediterranean, African, HIV-associated, and secondary to a preexisting immunodepressive state (hematological disorder, corticosteroid therapy, immunodepressive treatment). Whatever its form, Kaposi's sarcoma is probably associated with a chronic viral human herpes type 8 infection (HHV8).

EXEGESIS

This virus has been implicated in the pathogenesis of multiple myeloma (17 cases recorded to date). In the present study, a further case of Kaposi's sarcoma associated with multiple myeloma has been reported. However, Epstein-Barr virus, cytomegalovirus, hepatitis B and C, HIV and HHV8 serologies were negative. Radiotherapy on the lower limbs was initiated.

CONCLUSION

It is concluded that HHV8 does not appear to play a pathogenic role in cases of multiple myeloma, given the rarity of the association between Kaposi's sarcoma/multiple myeloma/HHV8.

Effects of isradipine or enalapril on blood pressure in salt-sensitive hypertensives during low and high dietary salt intake. MIST II Trial Investigators

This large multicenter study, tested the antihypertensive effects of isradipine, a dihydropyridine calcium channel blocker and enalapril, an angiotensin-converting enzyme inhibitor, in salt-sensitive hypertensive patients under low and high salt intake diets. After a 3-week (weeks -9 to -6) of ad lib salt diet, those patients who had a sitting diastolic blood pressure (SDBP) of > or =95 but < or =115 mm Hg qualified to enter a 3-week (weeks -6 to -3) placebo run-in low salt diet (50 to 80 mmol Na+/day). Then high salt (200 to 250 mmol Na+/day) was added to the placebo treatment for 3 weeks (weeks -3 to 0). Those patients who demonstrated an increase in SDBP > or =5 mm Hg from the low to high salt diet were considered salt sensitive and were randomized into a 4-week (weeks 0 to 4) double-blind treatment period of either isradipine 2.5 to 10 mg twice a day, enalapril 2.5 to 20 mg twice a day, or placebo. Then they entered a 3-week (weeks 4 to 7) placebo washout phase of low salt diet (50 to 80 mmol Na+/day). After week 7 and while the low salt diet was continued the patients were restarted on their double-blind treatment for 4 more weeks (weeks 7 to 11) and the study was completed. Of 1,916 patients screened, 464 were randomized into the double-blind treatment phase and 397 completed the study. Both isradipine and enalapril decreased the sitting systolic blood pressure (SSBP) and SDBP during the high salt diet, to a similar degree, whereas enalapril caused a greater reduction in SSBP and SDBP than isradipine during the low salt diet (11.3 +/- 1.2/7.7 +/- 0.7 mm Hg v 7.7 +/- 0.9/4.8 +/- 0.6 mm Hg, mean +/- SEM, respectively, P < .02). Within drugs, the effect of isradipine on blood pressure (BP) was higher during the high than the low salt diet (14.9 +/- 1.5 v 7.6 +/- 1.3 mm Hg for SSBP and 10.1 +/- 0.6 v 4.8 +/- 0.9 mm Hg for SDBP, P < .001), but enalapril exerted a similar effect during both diets. Because salt restriction lowered both SSBP and SDBP, the lowest BP achieved with both drugs were during the salt restriction phase.

Dissociating the role of the dorsolateral prefrontal and anterior cingulate cortex in cognitive control

Theories of the regulation of cognition suggest a system with two necessary components: one to implement control and another to monitor performance and signal when adjustments in control are needed. Event-related functional magnetic resonance imaging and a task-switching version of the Stroop task were used to examine whether these components of cognitive control have distinct neural bases in the human brain. A double dissociation was found. During task preparation, the left dorsolateral prefrontal cortex (Brodmann's area 9) was more active for color naming than for word reading, consistent with a role in the implementation of control. In contrast, the anterior cingulate cortex (Brodmann's areas 24 and 32) was more active when responding to incongruent stimuli, consistent with a role in performance monitoring.

Working memory for letters, shapes, and locations: fMRI evidence against stimulus-based regional organization in human prefrontal cortex

Investigations of working memory (WM) systems in the frontal cortex have revealed two stimulus dimensions along which frontal cortical representations may be functionally organized. One hypothesized dimension dissociates verbal from nonverbal WM processes, dividing left from right frontal regions. The second hypothesized dimension dissociates spatial from nonspatial WM, dividing dorsal from ventral frontal regions. Here we used functional magnetic resonance imaging to probe WM processes associated with three different types of stimuli: letters (verbal and nonspatial), abstract shapes (nonverbal and nonspatial), and locations (nonverbal and spatial). In a series of three experiments using the "n-back" WM paradigm, direct statistical comparisons were made between activation patterns in each pairwise combination of the three stimulus types. Across the experiments, no regions that demonstrated responses to WM manipulations were discovered to be unique to any of the three stimulus types. Therefore, no evidence was found to support either a left/right verbal/nonverbal dissociation or a dorsal/ventral spatial/nonspatial dissociation. While this could reflect a limitation of the present behavioral and imaging techniques, other factors that could account for the data are considered, including subjects' strategy selection, encoding of information into WM, and the nature of representational schemes in prefrontal cortex.

[Elective repair of infra-renal aortic aneurysm in octogenarians]

Age over 80 years is generally considered an independent risk factor in elective surgery for abdominal aortic aneurysm (AAA). As the general population increases in age, more elderly are likely to be candidates for such surgery. We studied prospectively 100 consecutive patients undergoing elective AAA surgery between 1992-1995. All were operated on by the same team of anesthetists and surgeons and all were transferred to the general ICU for at least the first 24 hours. 16 were above the age of 80 (Group I) and 84 below (Group II). We recorded preoperative factors (demographics, medical history, risk factor indices, EKG findings, as well as left ventricular ejection fraction (LVEF) and stress imaging when indicated); intraoperative factors (duration of surgery, size of aneurysm, complications and units of blood transfused); postoperative factors (length of ICU stay, duration of ventilation, APACHE II [Acute Physiological and Chronic Health Evaluation] and TISS [Therapeutic Intervention Scoring System] scores; complications in the ICU, need for readmission to the ICU, and mortality). In Group I LVEF was greater (p = 0.03) and aneurysm size significantly larger (p = 0.036), but there were no other significant differences between the 2 groups with regard to pre- and intraoperative data. Group I patients were not ventilated as long (p = 0.038), but there were no significant differences in outcome factors. Mortality for the whole group was 5% and was not significantly different in the 2 groups (1/16 in Group I and 4/84 in Group II). We conclude that there is no excess morbidity or mortality in octogenarians undergoing AAA surgery. However risk of the aneurysms rupturing is significantly greater since they are larger. We suggest that age not be considered the sole criterion for aneurysm repair, or at least not in selected patients with normal LVEF.

Benefits of lipid lowering on vascular reactivity in patients with coronary artery disease and average cholesterol levels: a mechanism for reducing clinical events?

BACKGROUND

The favorable effects of lowering low-density lipoprotein (LDL)-cholesterol on reducing clinical events in patients with coronary disease have been well established. The mechanisms responsible for this benefit, however, have not been fully understood. This study examined the impact of lipid-lowering therapy on endothelium-dependent vasoreactivity in a subgroup of patients after myocardial infarction with average cholesterol levels who participated in the Cholesterol Recurrent Events (CARE) study to determine whether an effect on endothelial function is a viable mechanism for the observed reduction in clinical events.

METHODS AND RESULTS

Participants were recruited from among volunteers in the CARE trial at 2 university-based outpatient cardiology clinics. Patients were randomly assigned to pravastatin or placebo. Plasma lipids were measured at baseline and semiannually thereafter. During the final 6 months of the trial, vasoreactivity was assessed by change in ultrasound-determined brachial artery diameter in response to blood pressure cuff-induced ischemia (endothelium-dependent) and to nitroglycerin, a direct vasodilator. Differences in response were examined between the 2 randomized groups. The relation between change in LDL-cholesterol from baseline to year 5 and the magnitude of endothelium-dependent vasodilation also was examined. There was significantly greater endothelium-dependent vasodilation observed in the pravastatin group compared with the placebo group (13% vs 8%, P =.0002), with no difference between the groups in their response to the endothelium-independent vasodilator nitroglycerin. The magnitude of the endothelium-dependent vasodilation was significantly correlated with the percent change in LDL-cholesterol from baseline to final visit (r = 0.49, P =.015).

CONCLUSIONS

These findings indicate that the use of pravastatin in patients after myocardial infarction with average cholesterol levels is associated with greater endothelium-dependent vasodilation compared with those who received placebo. The magnitude of this vasodilatory response is correlated to the reduction in LDL-cholesterol. This improvement in endothelium-dependent vasoreactivity may be a likely mechanism, at least in part, for the reduction in recurrent clinical events observed and reported in the CARE study.

The "benefits" of distractibility: mechanisms underlying increased Stroop effects in schizophrenia

Recent studies of selective attention in schizophrenia patients suggest a particular pattern of single-trial Stroop performance: increased facilitation but not interference in reaction times (RTs), combined with increased error interference. Our Stroop task analysis suggests that this pattern can be explained by a selective attention deficit if one accounts for (1) performance in the congruent condition; (2) the nature of the neutral stimulus; (3) the relationship between accuracy and RT; and (4) response set effects. To test these hypotheses, we examined Stroop performance in 40 DSM-IV schizophrenia patients and 20 healthy control subjects, using a range of neutral stimuli (color patches, noncolor words, color words not in the response set). The findings confirmed several of our predictions and the results were consistent with the hypothesis that abnormal Stroop performance in schizophrenia reflects a failure to adequately attend to the task-appropriate stimulus dimension (color). This inattention affects both the congruent and incongruent conditions and multiple points in the information processing pathway.