Depression and risk of sudden cardiac death after acute myocardial infarction: testing for the confounding effects of fatigue

OBJECTIVES: This study examined the impact of depressive symptoms and social support on 2-year sudden cardiac death (SCD) risk, controlling for fatigue symptoms. METHODS: Myocardial infarction (MI) patients (N = 671) participating in the Canadian Amiodarone Myocardial Infarction Arrhythmia Trial completed measures of depression, hostility, and social support. RESULTS: After controlling for significant biological predictors, psychosocial predictors of increased SCD risk in the survival analysis were greater social network contacts (RR = 1.04; 95% CI = 1.01-1.06; p < .007), lower social participation (RR = 0.98; 95% CI = 0.96-1.00; p < .05), and, in placebo-treated patients, elevated depressive symptoms (RR = 2.45; 95% CI = 1.14-5.35; p < .02). Fatigue was associated with SCD (RR = 1.31; 95% CI = 1.11-1.53; p < .001), and, when included in the model, diminished the influence of depression (RR = 1.73; 95% CI = 0.75-3.98; p = .20). When the cognitive-affective depressive symptoms were examined separately from somatic symptoms, there was a trend for an association between cognitive-affective symptoms and SCD in placebo-treated patients after controlling for fatigue (RR = 1.09; 95% CI = 0.99-1.19, p < .06). CONCLUSIONS: Symptoms of depression and fatigue overlap in patients with MI. The trend for the cognitive-affective symptoms of depression to be associated with SCD risk, even after controlling for dyspnea/fatigue, suggests that the association between depression and mortality after AMI cannot be entirely explained as a confound of cardiac-related fatigue. The independent contribution of social participation suggests a role of both depressive symptomatology and social factors in influencing mortality risk after MI.     

METHYLATION STATUS OF BCL6 DISTINGUISHES DNA SAMPLES FROM BENIGN AND MALIGNANT LYMPHOPROLIFERATIVE DISORDERS

INTRODUCTION: Core biopsy of the breast has become the method of choice for tissue diagnosis of screen detected microcalcifications and some mass lesions in many breast assessment centres. Biopsy results are not available until the following day. Imprint cytology of fresh breast core samples allows same-day reporting and patient counselling.
AIM: To determine the accuracy of core imprint cytology when compared with core biopsy diagnosis when used in a breast assessment centre setting.
METHODS: Core imprints (CI) were prepared and reported on all fresh core biopsies (CB) performed at the Sir Charles Gairdner Hospital Breast Centre from May to December 2000. Fresh core samples were placed on a glass microscope slide. Core radiographs were taken for microcalcification lesions (MC). A laboratory technician gently and quickly rolled the cores on the slide with fine forceps. The cores were fixed in formalin, processed and reported next day. The imprint slide was air dried and stained with DiffQuik. CI were reported using four categories: Insufficient, Benign, Indeterminate and Malignant. Counselling and planning for management were possible on the same day in women with malignant diagnoses. Clinicians were advised not to discuss negative or indeterminate CI results with women and to defer to the final CB report.
RESULTS: Cores were performed on 381 lesions. There were 83 carcinomas (38 in MC and 45 in masses) and 56 were called malignant on CI (absolute sensitivity 67.5%; 78.9% for MC and 57.8% for masses). 3 malignancies on CB were negative on CI giving a false negative rate of 3.6%. There were no false positive diagnoses. The predictive value of a benign diagnosis was 95.3%. There were no adverse effects in the histology of CB.
CONCLUSION: CI was an accurate method of providing an immediate diagnosis of malignancy in two thirds of malignancies confirmed on CB.     

Relation between extracellular [K+], membrane potential and contraction in rat soleus muscle: modulation by the Na+-K+ pump

An increased extracellular K⁺ concentration ([K⁺]₀) is thought to cause muscle fatigue. We studied the effects of increasing [K⁺]₀ from 4 mM to 8–14 mM on tetanic contractions in isolated bundles of fibres and whole soleus muscles from the rat. Whereas there was little depression of force at a [K⁺]₀ of 8–9 mM, a further small increase in [K⁺]₀ to 11–14 mM resulted in a large reduction of force. Tetanus depression at 11 mM [K⁺]_o was increased when using weaker stimulation pulses and decreased with stronger pulses. Whereas the tetanic force/resting membrane potential (E _M) relation showed only moderate force depression with depolarization from –74 to –62 mV, a large reduction of force occurred whenE _M fell to –53 mV. The implications of these relations to fatigue are discussed. Partial inhibition of the Na⁺-K⁺ pump with ouabain (10^–6 M) caused additional force loss at 11 mM [K⁺]₀. Salbutamol, insulin, or calcitonin gene-related peptide all stimulated the Na⁺-K⁺ pump in muscles exposed to 11 mM [K⁺ ₀] and induced an average 26–33% recovery of tetanic force. When using stimulation pulses of 0.1 ms, instead of the standard 1.0-ms pulses, force recovery with these agents was 41–44% which was significantly greater (P < 0.025). Only salbutamol caused any recovery ofE _M (1.3 mV). The observations suggest that the increased Na⁺ concentration difference across the sarcolemma, following Na⁺-K⁺ pump stimulation, has an important role in restoring excitability and force.     

Nucleolar organizer regions in transitional cell tumors of the bladder

The traditional silver staining technique that identifies nucleolar organizer region-associated proteins has recently been adapted and applied to paraffin sections, and used to examine changes in nucleolar organizer region numbers in a variety of benign and malignant conditions. We describe herein the enumeration of nucleolar organizer regions in a variety of benign and malignant conditions of the transitional epithelium of the urinary bladder. While there is a statistical separation between normal and neoplastic groups, there is a degree of overlap between normal, inflammatory, dysplastic, and neoplastic urothelium.     

Semiautomated determination of minimum bactericidal concentrations of antibiotics

Using a newly devised 50-channel photometer which records the opacity of growing bacterial cultures, it was shown that the time taken by cultures diluted 1/1000 in fresh broth to reach 50% of the opacity of a fully grown culture was inversely related to the concentration of organisms in the original culture. This relation was used to determine the numbers of survivors after exposure to benzylpenicillin and gentamicin alone and in combination. The procedure is commended as a labour-saving and potentially rapid method of obtaining comprehensive information on the bactericidal action and interaction of antibiotics.     

Changes of tension and [Ca2+]i during β-adrenoceptor activation of single,intact fibres from mouse skeletal muscle

-Adrenergic agonists increase tension production in fast-twitch skeletal muscle, but the underlying mechanism is unknown. In the present study we have exposed intact, single fibres from a mouse muscle to the ₂-adrenergic agonist terbutaline. Fibres were stimulated to produce 350-ms tetani at 20–100 Hz while measuring the myoplasmic Ca²⁺ concentration ([Ca²⁺]_i) and tension. The fluorescent indicator Indo-1 was used to measure [Ca²⁺]_i. Application of terbutaline resulted in marked increases of both tetanic [Ca²⁺]_i and tension. Terbutaline had no significant effect on myofibrillar function as judged from normal Ca²⁺ sensitivity and tension production at saturating [Ca²⁺]_i. The rate of [Ca²⁺]_i and tension decline during relaxation was not affected by terbutaline, thus indicating a normal function of the sarcoplasmic reticulum (SR) Ca²⁺ pumps. The effect of terbutaline developed gradually over 5–10 min when fibres were stimulated each minute; the full effect of terbutaline was also obtained after a 10-min rest period in terbutaline. The [Ca²⁺]_i at rest was not affected by terbutaline. In conclusion, -adrenergic stimulation increases tetanic tension by enhancing SR Ca²⁺ release.     

Initial evaluation of a continuous speech recognition program for radiology

The aims of this work were to measure the accuracy of one continuous speech recognition product and dependence on the speaker's gender and status as a native or nonnative English speaker, and evaluate the product's potential for routine use in transcribing radiology reports. IBM MedSpeak/Radiology software, version 1.1 was evaluated by 6 speakers. Two were nonnative English speakers, and 3 were men. Each speaker dictated a set of 12 reports. The reports included neurologic and body imaging examinations performed with 6 different modalities. The dictated and original report texts were compared, and error rates for overall, significant, and subtle significant errors were computed. Error rate dependence on modality, native English speaker status, and gender were evaluated by performing ttests. The overall error rate was 10.3 +/- 3.3%. No difference in accuracy between men and women was found; however, significant differences were seen for overall and significant errors when comparing native and nonnative English speakers (P = .009 and P = .008, respectively). The speech recognition software is approximately 90% accurate, and while practical implementation issues (rather than accuracy) currently limit routine use of this product throughout a radiology practice, application in niche areas such as the emergency room currently is being pursued. This methodology provides a convenient way to compare the initial accuracy of different speech recognition products, and changes in accuracy over time, in a detailed and sensitive manner.     

Differential effect of nerve fiber structure on block by local anesthetic

The incidence of conduction block by lidocaine 0.3 mmol/l (8.1 mg/dl) in several successive lengths of individual afferent axons of rabbit was compared. The conduction velocity of the axons was either "slow," "intermediate" (1.3-4 m/s), or "fast." The "intermediate" group showed a higher incidence of proximal acceleration of conduction (P less than 0.001) and a greater incidence of block (P less than 0.001) than the "slow" and "fast" fiber groups. The results were interpreted as indicating that the fibers of the "intermediate" group had an unmyelinated peripheral and a myelinated proximal length, with a junctional heminodal region that was the seat of the high sensitivity to block. The potential clinical significance of the observation is discussed in terms of the known distribution of heminodes in the peripheral nervous system.     

Effects of chronic chlorpromazine or lithium administration on ageing-related lipopigment in rat Purkinje neurones

Ageing-related accumulation of neuronal lipopigment is considered to be debris from processes of renewal of cellular constituents, but can also reflect cell damage and certain diseases. Chlorpromazine (an example of a class of drug chronically administered in psychiatric practice) has been reported to reduce neuronal lipopigment accumulation, and the present study investigated the effects of 28 weeks of chlorpromazine administration on lipopigment in rat Purkinje neurones. The effects of 26 weeks of lithium administration (also chronically administered in psychiatric practice) were also studied. Lipopigment was identified by fluorescence microscopy and the area enclosed by an outline of each discrete region of lipopigment was measured. While lithium administration was not associated with significant changes in lipopigment variables, chlorpromazine administration was associated with a significant (p=0.001) reduction in the number of discrete lipopigment regions and with significant (p=0.001) differences in the numbers of discrete lipopigment regions in various size categories. The findings are similar to those associated with the administration of acetyl-L-carnitine (which has been reported to reduce some morphological and behavioural associations of brain ageing) and are compatible with a reduction in the rate of lipopigment formation. This could reflect an adverse effect of chlorpromazine administration (i.e. reduced functional activity of neurones) or a beneficial effect (i.e. a reduction in ageing-related changes).     

Evaluating the hazard of dodecyl alkyl sulphate to natural ecosystems using indigenous protistan communities

The effect of the surfactant dodecyl alkyl sulphate (C12AS) on the structure and function of lotic protistan assemblages was examined using the Experimental Stream Facility (ESF) operated by the Procter and Gamble Company. Population- and community-level responses to C12AS were monitored on introduced substrates placed in the channels 28 days prior to dosing (mature communities) as well as those placed in the channels on day 0 of dosing (immature communities), to allow for a broad assessment of the effect of the chemical on processes contributing both to community development and maintenance. C12AS appeared to elicit a subsidy response from the native protistan assemblage which may have resulted from both positive and negative responses at trophic levels above and below the assemblage. Protistan responses to the surfactant tended to occur more rapidly and be more sensitive than those documented for invertebrates and fish. C12AS elicited a modest response (i.e. a 20% change) from several reliable parameters including community respiration (reduced dissolved oxygen at 289 g per L), protozoan species richness (increased at 63 g per L) and protozoan community composition (increased dissimilarity at 1254 g per L). Responses to C12AS exceeded expected exposures in the real world by a factor of six or greater thereby indicating that the hazard of exposure to C12AS to stream communities is low. The results of this study support the use of mesocosms as decisive tools for evaluating the hazard posed by consumer product chemicals to natural communities and ecosystems