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Vesa Virtanen

Publications and source records attributed to Vesa Virtanen.

14 recordsLinked to original sources
PubMed2006

Reindeer beta-lactoglobulin crystal structure with pseudo-body-centred noncrystallographic symmetry.

Reindeer beta-lactoglobulin (betaLG) belongs to the lipocalin superfamily. Its DNA and protein sequences have been determined and showed that it had nine residue changes from bovine betaLG. Reindeer betaLG, the structure of which was finally determined at 2.1 A resolution in space group P1, crystallized in a unit cell that is both P2-like and P2(1)-like owing to the presence of an almost perfect (but noncrystallographic) body-centring vector. The non-body-centred data could only be observed using a very bright synchrotron beam and a novel refinement strategy was adopted to enable us to use the weak h + k + l = 2n + 1 reflections.

Animals↗
PubMed2006

Microplate screening assay for binding of ligands to bovine or reindeer beta-lactoglobulins.

Several analytical methods have been used to determine whether ligands bind to bovine beta-lactoglobulin (betaLG). The most common methods are based on fluorescence quenching. We have miniaturised this method from a quartz cell to a 96-well plate. The miniaturisation was evaluated using retinol. The binding constants between the two methods demonstrated a good correlation. The 96-well plate method is much faster and allows many references to be used in the same analysis. The miniaturised method was used to study the binding of three different ligands (4-HPR, arotinoid, warfarinyl palmitate) modelled to bind to betaLG. The binding data showed that all of these ligands bound to betaLG. The method was further used to demonstrate that reindeer betaLG could also bind the four ligands in the same way as bovine betaLG. Because one aim is to use bovine and reindeer betaLG as a binder molecule for aliments in e.g. functional food or for drugs, the influence of pH was also studied and demonstrated that short-term acidic conditions had only a slight effect on the binding properties.

Animals↗
PubMed2006

Prediction of coronary artery disease by transesophageal echocardiographic detection of thoracic aortic plaque in patients with chronic kidney disease.

BACKGROUND/AIMS: Our aim was to examine the significance of thoracic aortic plaque detected by transesophageal echocardiography (TEE) in the prediction of coronary artery disease (CAD) in patients with chronic kidney disease (CKD). METHODS: We examined 118 patients (mean age 52 +/- 12 years) with CKD and followed them for a mean of 3.4 +/- 0.8 years. The study group included 52 predialysis patients with moderate to severe CKD (plasma creatinine > or = 200 micromol/l), 32 patients on dialysis treatment, and 34 renal transplant recipients. At baseline, TEE was performed to evaluate thoracic aortic atherosclerosis. CAD was defined by a history of a documented myocardial infarction, a coronary angiogram or a post-mortem autopsy finding showing significant occlusive CAD by the end of the follow-up period. RESULTS: CAD was documented in 31 (26%) of the 118 study patients. The presence of thoracic aortic plaque had a sensitivity of 100% and a specificity of 37% for CAD and the positive and negative predictive values were 36 and 100%, respectively. In the subset of 36 patients with morphological findings of coronary arteries by angiogram or autopsy, the presence of large thoracic aortic plaques (> or = 3 mm in diameter) had a 73% sensitivity and 90% specificity for significant coronary artery stenosis. The positive and negative predictive values were 95 and 56%, respectively. CONCLUSION: TEE may be used for detecting high-risk patients with CKD; the absence of thoracic aortic plaque predicted the absence of CAD, and the presence of large aortic plaques predicted significant coronary artery stenosis.

Adult↗
PubMed2006

Enterocyte and M-cell transport of native and heat-denatured bovine beta-lactoglobulin: significance of heat denaturation.

The three-dimensional structure, digestibility, and immunological properties of bovine beta-lactoglobulin (beta-lg) are modified by heat treatments used in processing of liquid milk products. Because it is not known if such treatments also modify the intestinal transport properties of beta-lg, the transport of native and heat-denatured bovine beta-lg was investigated in experimental cell models using Caco-2 cells and M cells. Transport of beta-lg labeled with a fluorescent marker was followed with fluorometric measurements, electrophoretic analyses, and fluorescence microscopy. The data show that both cell types transported native beta-lg more efficiently than they did heat-denatured beta-lg. In addition, M cells transported native beta-lg more than Caco-2 cells. Transport of native and heat-denatured beta-lg was transcellular. The electrophoretic data also suggest that heat-denatured beta-lg may have degraded more than native beta-lg during the transport.

Animals↗
PubMed2006

SCN5A mutation associated with cardiac conduction defect and atrial arrhythmias.

INTRODUCTION: We aimed at identifying the molecular defect underlying the clinical phenotype of a Finnish family with a cardiac conduction defect and atrial arrhythmias. METHODS AND RESULTS: A large Finnish family was clinically evaluated (ECG, 24-hour ambulatory ECG, echocardiography). We performed linkage analysis with markers flanking the SCN5A gene and subsequently sequenced the SCN5A gene. Five family members had atrial arrhythmias and intracardiac conduction defects, and due to bradycardia needed a pacemaker when adolescents. No heart failure or sudden cardiac death was observed. Left ventricle dilatation was seen in one individual and three individuals had a slightly enlarged right ventricle. Premature death due to stroke occurred in one subject during the study, and two other members had suffered from stroke at young age. Linkage analysis favored the role of the SCN5A gene in disease pathogenesis, and direct sequencing disclosed D1275N mutation. This alteration was present not only in all six affected individuals, but also in two young individuals lacking clinical symptoms. CONCLUSIONS: Cardiac conduction defect and atrial arrhythmias in a large Finnish family appear to result from the SCN5A D1275N mutation. Although no sudden cardiac death was recorded in the family, at least three affected members had encountered brain infarction at the age of 30 or younger.

Atrial Fibrillation↗
PubMed2006

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Journal Article↗
PubMed2005

Atrial fibrillation in elderly patients after cardiac surgery: postoperative hemodynamics and low postoperative serum triiodothyronine.

OBJECTIVE: The purpose of this study was to evaluate serum triiodothyronine levels as a trigger of postoperative atrial fibrillation (AF) in elderly patients undergoing cardiac surgery and to study the possible association of serum triiodothyronine levels with preoperative and postoperative hemodynamics. DESIGN: Prospective study. SETTING: University hospital. PARTICIPANTS: Forty-six consecutive nonemergency patients 65 years or older undergoing cardiac surgery during 1999 to 2000 in Tampere University Hospital, Tampere, Finland. INTERVENTIONS: Free serum T3 concentration was used as a measure of serum triiodothyronine levels. Samples were taken preoperatively, on the fourth postoperative day, and at the 3-month follow-up. The hemodynamic state of the patients was estimated by whole-body impedance cardiography preoperatively, during the intensive care unit period, daily until the fourth postoperative day, and at the 3-month follow-up. MEASUREMENTS AND MAIN RESULTS: AF occurred in 43% of the patients. The patients in the AF group had significantly more grafts (3.9 v 3.1, p = 0.02), and there was a small difference in age between the AF and non-AF groups (73 years v 69 years, p = 0.06). The free T3 concentration on the fourth postoperative day was significantly lower in the AF group (3.5 nmol/L v 4.6 nmol/L, p = 0.04). In logistic regression analysis, the independent predictors of AF were age, number of grafts, and serum free T3 concentration on the fourth postoperative day. In the group with low T3 concentration, the cardiac index was lower (1.4 v 1.8, p = 0.05) and the systemic vascular resistance index was higher (4,064 v 2,969, p = 0.04) but only immediately after the operation. Although the AF mostly appeared during the second to fourth postoperative days, there were no longer any differences in the hemodynamic state at that time. CONCLUSIONS: In a group of elderly patients undergoing cardiac surgery, there was a strong association between a postoperative decrease of serum triiodothyronine levels and atrial fibrillation. The decrease of serum triiodothyronine levels was related to the changes of hemodynamic parameters only in the immediate postoperative period.

Aged↗
PubMed2005

Microvolt T-wave alternans during exercise and pacing in patients with acute myocardial infarction.

Cardiac Arrhythmias and Risk Stratification after Myocardial infarction (CARISMA) is a prospective multicenter trial designed to document the incidence of cardiac arrhythmias after acute myocardial infarction (AMI), and to assess the predictive accuracy of various arrhythmic risk markers. In this substudy of the CARISMA trial, microvolt T-wave alternans (TWA) was assessed with specific equipment 6 weeks after AMI during bicycle exercise, atrial (A) pacing, and simultaneous ventricular and atrial (V + A) pacing in 80 patients with left ventricular ejection fraction (LVEF) <40%. The agreement between the acute test results was determined by overall proportion of concordance and the kappa statistic. Sustained TWA was observed in 24, 45, and 50% of the patients during the exercise test, A pacing, and V + A pacing, respectively. The number of indeterminate TWA was significantly lower during V + A pacing (n = 7) than exercise test (n = 34). The TWA concordance rate was 71% between exercise and V + A pacing (kappa= 0.53, P = 0.001), 79% between exercise and A pacing (kappa= 0.54, P < 0.001), and 95% between the two pacing modes (kappa= 0.89, P < 0.001). Patients with positive TWA in all tests had lower LVEF (28 +/- 7% vs 35 +/- 9%, P < 0.01) and wider QT dispersion (99 +/- 44 ms vs 67 +/- 38 ms, P < 0.01) than those with inconsistent test result. The low number of indeterminate tests and high concordance between the test results indicate that V + A pacing may provide a valuable means to assess TWA in patients who cannot complete the exercise test.

Cardiac Pacing, Artificial↗
PubMed2004

Seropositivity for Helicobacter pylori antibodies is associated with lower occurrence of venous bypass graft occlusion.

Common chronic infections including those caused by cytomegalovirus (CMV), herpes simplex viruses (HSV), Helicobacter pylori and Chlamydia pneumoniae have previously been related to increased risk of coronary heart disease (CHD). We investigated the association between serology of these chronic infections and coronary bypass graft occlusions in 61 patients. As a result, IgG seropositivity rate against H. pylori was higher among patients without occlusion (82%) than in those with occlusion (45%) or apparently healthy controls (57%) (p = 0.004 and p = 0.008, respectively). In conclusion, H. pylori infection, as judged by IgG seropositivity, is associated with lower occurrence of venous bypass graft occlusion in patients with CHD and may thus be connected with better outcome and prognosis of CHD patients after bypass graft surgery.

Adult↗
PubMed2004

The effect of isolated ultrafiltration on Doppler-derived indices of left ventricular diastolic function.

BACKGROUND: Haemodialysis (HD) is associated with acute changes simultaneously in fluid status (ultrafiltration) and in many biochemical parameters (dialysis). Reports on the effects of these changes on left ventricular (LV) diastolic function are scant. This study evaluated the effect of isolated ultrafiltration (UF) and subsequent HD with minimal fluid removal on Doppler-derived indices of LV diastolic function in patients who were asymptomatic and stable on HD. METHODS: In 11 HD cases, the 5 h treatment session was divided into a 2.5 h period of fluid removal without dialysis (UF phase) and 2.5 h of dialysis with minimal fluid removal (HD phase). We examined the following parameters of LV diastolic function echocardiographically: early rapid filling (Emax), atrial peak filling (Amax), Emax/Amax ratio, isovolumic relaxation time (IVRT) and deceleration time of the E-wave (DT). RESULTS: During the UF phase, Emax decreased from 0.82 +/- 0.2 to 0.62 +/- 0.2 m/s (P = 0.003), Amax decreased from 0.72 +/- 0.2 to 0.63 +/- 0.2 m/s (P = 0.042) and the ratio Emax/Amax did not change (P = NS). During the HD phase, Emax increased from 0.62 +/- 0.2 to 0.72 +/- 0.2 m/s (P = 0.018), Amax increased from 0.63 +/- 0.2 to 0.70 +/- 0.3 m/s (P = NS) and the Emax/Amax ratio remained unchanged (P = NS). IVRT was prolonged in 10 out of 11 patients at the start of the UF phase and it was further prolonged from 142 +/- 40 to 171 +/- 55 ms (P = 0.03) during the UF phase. IVRT did not alter during the HD phase (P = NS). During the UF phase, DT increased from 175 +/- 83 to 244 +/- 119 and it decreased from 244+/-119 to 209 +/- 98 in the HD phase, but both changes were statistically insignificant. No statistically significant correlations were observed between the changes in the Doppler indices of diastolic function and changes in biochemical parameters during the HD phase. CONCLUSIONS: UF affects the parameters Emax, Amax and IVRT used to evaluate LV diastolic function. The changes in Emax and Amax during the HD phase are due to fluid refilling from tissues into the blood space, HD as such having no effect on Doppler indices. However, isolated UF or HD does not affect the Emax/Amax ratio. Emax and IVRT seem to be the most volume-sensitive parameters.

Female↗
PubMed2003

Risk factors for aortic atherosclerosis determined by transesophageal echocardiography in patients with CRF.

BACKGROUND: The significance of various risk factors for cardiovascular disease (CVD) in the pathogenesis of atherosclerosis in patients with chronic renal failure (CRF) is, to a great deal, unresolved. The high risk for CVD in patients with CRF may be caused by the high prevalence of recognized risk factors for CVD or by factors characteristic of CRF in these patients. In this prospective cross-sectional study, we examined risk factors for thoracic aortic atherosclerosis in a population of patients with CRF consisting of predialysis and dialysis patients, as well as renal transplant recipients. METHODS: Of 118 patients, 52 patients had moderate to severe predialysis CRF, 32 patients were on dialysis treatment, and 34 patients were renal transplant recipients. Mean age was 52 +/- 12 years, and 35 patients (30%) had diabetes. Multiplane transesophageal echocardiography (TEE) was performed using local anesthesia. RESULTS: Large aortic plaques (LAPs; > or = 3.0 mm in diameter) were found in 39 patients (33%). In univariate analysis, age, duration of hypertension, pulse pressure, low diastolic blood pressure, elevated fibrinogen level, C-reactive protein level, total cholesterol level, low-density lipoprotein cholesterol level, and duration of dialysis or a functioning renal transplant were significantly associated (P < 0.05) with LAP. In multivariate analysis, age, duration of hypertension, and total cholesterol level were associated with LAP. CONCLUSION: Results of the present TEE study suggest that in addition to duration of hypertension and renal disease, hypercholesterolemia has a role in the pathogenesis of atherosclerosis in patients with CRF.

Aged↗
PubMed2002

Association of mannan-binding lectin deficiency with venous bypass graft occlusions in patients with coronary heart disease.

We investigated the effect of mannan-binding lectin (MBL) deficiency on the susceptibility to bypass graft occlusion in 62 patients with coronary heart disease. MBL deficiency appeared to be associated with occlusion (p = 0.0099). A high level of anti-cardiolipin IgG as well as the number of venous bypass grafts were also involved (p = 0.0018 and p = 0.0104, respectively). Since early occlusion (<5 years after surgery) of a venous bypass graft is considered to be caused by thrombosis or fibro-intimal hyperplasia superimposed by thrombosis, our finding also implies an association of MBL deficiency with thrombotic events. It remains unclear whether the previously confirmed effect of MBL deficiency in coronary disease is mediated through this possible thrombotic mechanism, or whether plaque formation is also involved in the process. Further studies are clearly warranted.

Adult↗
PubMed1998

Influence of Pulsed-Doppler Sample Volume Location and Upper Body Tilt on Left Ventricular Filling Indices in Healthy Persons.

Doppler echocardiographic analysis of mitral flow is a noninvasive tool for analyzing left ventricular diastolic function. Changes in preload alter both normal and abnormal Doppler patterns of left ventricular filling. The velocities of mitral flow measured by transthoracic pulsed-Doppler echocardiography are different when measured at the mitral leaflet tips and at the mitral annulus. Transesophageal echocardiography provides an excellent image of cardiac anatomy whereby it is possible to place the Doppler sample volume exactly at the mitral annulus or at the tips of mitral leaflets. We studied with the use of transesophageal echocardiography how changes in preload and measurement at the annulus or valve tips affect the velocities of mitral flow. Upper body-up tilting (60 degrees ) decreased maximum E wave velocity by 16% and, hence, E/A ratio by 15%. A wave did not change by tilt. E wave velocity was 13%-15% lower at the annulus than at the tips of the mitral valve in both the supine and tilt position. E/A ratio was significantly higher at the tips than at the annulus of the mitral valve (supine, P = 0.048; tilt, P = 0.001). E/A ratio was 38% lower if the measurements were done at the annulus in the tilt position than at the tips with the patient lying horizontal. It may be important for pulsed-Doppler mitral flow-velocity measurements to be standardized for sample volume location and for body position.

Journal Article↗