Features of ST segment and T-wave in exercise-induced myocardial ischemia evaluated with multichannel magnetocardiography

BACKGROUND AND AIM: Magnetocardiography (MCG) is a novel, non-contact mapping technique to record cardiac magnetic field. We evaluated MCG criteria for myocardial ischemia in stress testing. METHODS: Multichannel MCG over frontal chest was performed in 44 patients with coronary artery disease (CAD) and 26 healthy controls during supine bicycle exercise test. Of the 44 patients 16 had anterior, 15 posterior, and 13 inferior ischemia documented by coronary angiography and exercise thallium scintigraphy. ST amplitude, ST slope, T-wave amplitude, and ST-T integral were measured. The optimal sites for detecting the ischemia-induced changes on MCG were sought. The orientation of the magnetic field was also determined. RESULTS: The optimal sites for the decrease of ST slope, ST amplitude, T-wave amplitude, and ST-T integral were over the abdomen. The reciprocal increase of these parameters was found over the left parasternal area. The optimal sites were approximately the same for all patient groups. In single-vessel disease patients without previous myocardial infarction (MI), ST slope increase and ST elevation performed the best (area under the receiver operating characteristic curve 92% and 90%, respectively). In post-MI patients with triple-vessel disease the decrease of T-wave amplitude and ST slope performed the best (area under curve 91%, for both). The magnetic field orientation at ST segment performed equally well as the other ST parameters. In stepwise logistic regression analysis, by use of the presence of CAD as the dependent parameter, ST slope increase and ST peak gradient orientation entered the model. CONCLUSIONS: Various ST segment and T-wave parameters detect ischemia in MCG. ST amplitude performs especially well in non-MI patients with less severe CAD. In advanced CAD late development of T-wave amplitude might be more sensitive to ischemia than ST amplitude.     

Cancer incidence and mortality among Finnish asbestos sprayers and in asbestosis and silicosis patients

Cohorts of Finnish asbestos sprayers and of asbestosis and silicosis patients were followed for cancer with the aid of the Finnish Cancer Registry in the period 1967–1994. Compared with the cancer incidence of the total Finnish population, asbestos sprayers had an increased risk for total cancer (standardized incidence ratio [SIR] 6.7, 95% confidence interval [95% CI] 4.2–10); lung cancer (SIR 17, 95% CI 8.2–31); and mesothelioma (SIR 263, 95% CI 85–614). The SIR of the asbestosis patients was 3.7 (95% CI 2.8–5.0) for all sites, 10 (95% CI 6.9–14) for lung cancer, and 65 (95% CI 13–188) for mesothelioma. The silicosis patients also had significantly high SIR values for all sites (1.5, 95% CI 1.0–2.1) and lung cancer (2.7, 95% CI 1.5–4.5). The values for the SIR and the standardized mortality ratio for all sites and lung cancer were very similar, and therefore it seems that both are reliable indicators of the occurrence of occupational cancer. It was concluded that pneumoconioses patients and asbestos-exposed workers have a markedly elevated risk for cancer. Asbestos-induced occupational cancers are not only diseases of the elderly, since the relative risk is high also for middle-aged people. Am. J. Ind. Med. 31:693–698, 1997. © 1997 Wiley-Liss, Inc.     

Differences in Acoustic Properties of Intact and Degenerated Human Patellar Cartilage During Compression

Ultrasound indentation measurements have been shown to provide means to assess cartilage integrity and mechanical properties. To determine cartilage stiffness in the ultrasound indentation geometry, cartilage is compressed with an ultrasound transducer to determine the induced strain from the ultrasound signal using the time-of-flight principle. As the ultrasound speed in cartilage has been shown to vary during compression, the assumption of constant speed generates significant errors in the values of mechanical parameters. This variation in ultrasound speed has been investigated in intact cartilage, however, its existence and significance in degenerated tissue is unknown. In the present study, we investigate this issue with both intact and spontaneously degenerated human tissue. To accomplish this aim, we determined ultrasound speed and attenuation in human patellar cartilage (n = 68) during mechanical loading. For reference, cartilage mechanical properties and proteoglycan, collagen and water contents were determined. The acoustic properties were related to the composition and mechanical properties of the samples. Ultrasound speed showed significant, site-dependent variation and it was significantly associated (r = 0.79–0.81, p < 0.01) with the mechanical properties of cartilage. The compression related decrease in ultrasound speed showed statistically significant variation between different stages of degeneration. Error simulations revealed that changes in ultrasound speed during 2% compression could generate errors up to 15% in the values of elastic moduli of samples with early degeneration, if determined with the ultrasound indentation technique. In samples with advanced degeneration, the error was significantly (p < 0.05) smaller being 2% on average. As the compression related variation in ultrasound speed was lower in more degenerated samples, the mechanical parameters could be diagnosed more reliably in tissue showing advanced degeneration. The present results address the need to consider possible uncertainties in mechano-acoustic measurements of articular cartilage and call for methods to correct the effect of variable sound speed during compression. (E-mail: panu.kiviranta@uku.fi)     

Corticosteroids for the prevention of atrial fibrillation after cardiac surgery: a randomized controlled trial

Context  Atrial fibrillation (AF) is the most common arrhythmia to occur after cardiac surgery. An exaggerated inflammatory response has been proposed to be one etiological factor. Objective  To test whether intravenous corticosteroid administration after cardiac surgery prevents AF after cardiac surgery. Design, Setting, and Patients  A double-blind, randomized multicenter trial (study enrollment August 2005–June 2006) in 3 university hospitals in Finland of 241 consecutive patients without prior AF or flutter and scheduled to undergo first on-pump coronary artery bypass graft (CABG) surgery, aortic valve replacement, or combined CABG surgery and aortic valve replacement. Intervention  Patients were randomized to receive either 100-mg hydrocortisone or matching placebo as follows: the first dose in the evening of the operative day, then 1 dose every 8 hours during the next 3 days. In addition, all patients received oral metoprolol (50-150 mg/d) titrated to heart rate. Main Outcome Measure  Occurrence of AF during the first 84 hours after cardiac surgery. Results  The incidence of postoperative AF was significantly lower in the hydrocortisone group (36/120 [30%]) than in the placebo group (58/121 [48%]; adjusted hazard ratio, 0.54; 95% confidence interval, 0.35-0.83; P = .004; number needed to treat, 5.6). Compared with placebo, patients receiving hydrocortisone did not have higher rates of superficial or deep wound infections, or other major complications. Conclusion  Intravenous hydrocortisone reduced the incidence of AF after cardiac surgery. Trial Registration  clinicaltrials.gov Identifier: NCT00442494      

Noise amplification in parallel whole‐head ultra‐low‐field magnetic resonance imaging using 306 detectors

In ultra‐low‐field magnetic resonance imaging, arrays of up to hundreds of highly sensitive superconducting quantum interference devices (SQUIDs) can be used to detect the weak magnetic fields emitted by the precessing magnetization. Here, we investigate the noise amplification in sensitivity‐encoded ultra‐low‐field MRI at various acceleration rates using a SQUID array consisting of 102 magnetometers, 102 gradiometers, or 306 magnetometers and gradiometers, to cover the whole head. Our results suggest that SQUID arrays consisting of 102 magnetometers and 102 gradiometers are similar in g‐factor distribution. A SQUID array of 306 sensors (102 magnetometers and 204 gradiometers) only marginally improves the g‐factor. Corroborating with previous studies, the g‐factor in 2D sensitivity‐encoded ultra‐low‐field MRI with 9 to 16‐fold 2D accelerations using the SQUID array studied here may be acceptable. Magn Reson Med 70:595–600, 2013. © 2012 Wiley Periodicals, Inc.     

Association between type 2 diabetes and exposure to persistent organic pollutants

OBJECTIVE

The prevalence of type 2 diabetes is increasing alarmingly in both developed and developing countries. Recently, exposure to persistent organic pollutants (POPs) has been associated with the prevalence of type 2 diabetes. The purpose of this cross-sectional study is to examine the association between type 2 diabetes and POP exposure in the Helsinki Birth Cohort Study.

RESEARCH DESIGN AND METHODS

The cohort consists of 8,760 people born in Helsinki during 1934–1944, before the global POP emission peak. In 2003, a clinical examination was performed, including blood sampling for laboratory analyses of serum lipids and POPs. Complete data from the examination were available for 1,988 participants. The concentrations of each POP were categorized into four groups on the basis of percentile intervals, and logistic regression was performed to examine diabetes prevalence across the POP categories, adjusting for sex, age, waist circumference, and mean arterial pressure and using the lowest category as the reference group.

RESULTS

Among the participants with the highest exposure to oxychlordane, trans-nonachlor, 1,1-dichloro-2,2-bis-(p-chlorophenyl)-ethylene (p,p’-DDE, and polychlorinated biphenyl 153, the risk of type 2 diabetes was 1.64–2.24 times higher than that among individuals with the lowest exposure (P_lin = 0.003–0.050, where P_lin is the P value for linear trend across POP categories). In the stratified analysis, the associations between type 2 diabetes and oxychlordane and trans-nonachlor remained significant and were strongest among the overweight participants. Exposure to 2,2′,4,4′-tetrabromodiphenyl ether (BDE 47) and 2,2′,4,4′,5,5′-hexabromodiphenyl ether (BDE 153) was not associated with type 2 diabetes.

CONCLUSIONS

This study confirms the association between type 2 diabetes and adult-only exposure to organochlorine pesticides in a general urban population.The prevalence of type 2 diabetes is increasing alarmingly in both developed and developing countries. The disease has traditionally been regarded as a multifactorial disorder, with a strong genetic component and lifestyle influences. Lately, it has been suggested that, in addition to the conventional risk factors, which include genetic susceptibility, obesity, physical inactivity, and an unhealthy diet, environmental factors may have a significant contribution. Specifically, exposure to persistent organic pollutants (POPs) has been shown to have a strong positive association with type 2 diabetes and related metabolic conditions (1–8).POPs are a diverse group of ubiquitous environmental contaminants, characterized by toxicity, slow degradation, lipid solubility, and accumulation in the food chain. In numerous cross-sectional studies performed during the last decade, associations between type 2 diabetes and exposure to polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs), brominated flame retardants (polybrominated diphenylethers [PBDEs]), and some organochlorine pesticides (OCPs) were observed (1–8). So far, the strongest indications regarding the positive association between POPs and type 2 diabetes within the general population have been obtained from a cross-sectional study in the U.S. (the National Health and Nutrition Examination Survey [NHANES]) (5–7). Lee et al. (5) observed that the prevalence of type 2 diabetes among the most exposed subgroup was 38 times higher than that among the least exposed group. It is striking that obesity was found to be a risk factor for type 2 diabetes and insulin resistance only in association with increased concentrations of POPs (5). The association between POPs and impaired glucose regulation was confirmed in in vitro and in vivo (9–11) studies.Human exposure to the majority of POPs occurs mainly through diet and, especially, foods of animal origin. In Finland, the most important source of POPs is Baltic Sea fatty fish, such as Baltic herring (Clupea harengus membras) and salmon (Salmo salar) (12). Although human exposure to POPs such as PCDD/Fs and PCBs in the Baltic region has been declining during the last 3 decades (13), these compounds are still detectable in human samples. In contrast to PCDD/Fs and PCBs, the concentrations of many emerging chemicals that hold a potential for health threat such as PBDEs, which are widely used as flame retardants, have recently increased in humans (14). POPs are persistent in the body, and measurements from serum are assumed to reflect lifetime exposure.The purpose of the present cross-sectional study is to examine the association between type 2 diabetes and POP exposure in the Helsinki Birth Cohort Study, which represents a general adult urban Finnish population. The cohort consists of people who were born in the 1930s and 1940s, well before the global POP emissions peaked, and their exposure during the fetal and childhood period has probably been very low. However, during their adulthood, they experienced a steep increase in environmental POP concentrations (15). Therefore, this population provides an excellent opportunity to study the association between adult exposure to POPs and type 2 diabetes.