Biomedical subjects

P Korhonen

Publications and source records attributed to P Korhonen.

At least 19 recordsLinked to original sources

PubMed2002

Heart rate adjustment of magnetic field map rotation in detection of myocardial ischemia in exercise magnetocardiography.

AIMS: We studied the capability of heart rate (HR) adjusted change in multichannel magnetocardiogram (MCG) to detect exercise-induced ischemia. METHODS AND RESULTS: The MCG and 12-lead ECG were recorded simultaneously during supine exercise testing in 17 healthy controls and 24 patients with single vessel coronary artery disease (CAD). In the MCG analysis, we plotted the orientation of the magnetic field map (MFM) against the HR in each cardiac cycle during recovery. A regression line was fitted to the data and the line slope (degrees/bpm) was determined. In the ECG, the ST-segment depression vs HR (ST/HR) slope was evaluated. The HR adjusted MFM rotation was more extensive in the pooled CAD group, and in all subgroups with different stenosed vessel, than in the control group at the ST-segment (1.5 +/- 2.1 degrees/bpm vs 0.29 +/- 0.25 degrees/bpm, p < 0.0005) and at the T-wave apex (0.95 +/- 0.81 degrees/bpm vs 0.24 +/- 0.25 degrees/bpm, p < 0.0005). Areas under the receiver operating characteristic curves of the HR adjusted MFM rotation at the ST-segment (88.5%) and the T-wave (86.0%) were higher than the ones without HR adjustment (75.5% and 68.1%, respectively), and higher than the area of ST/HR slope in the ECG (80.2%). CONCLUSION: HR adjusted MFM rotation detects transient ischemia independent of the stenosed vessel. HR adjustment improves the performance of the MCG in ischemia detection by the analysis of the ST-segment and the T-wave. The MCG was superior to the 12-lead ECG.

Aged↗

PubMed2002

Isolated ultrafiltration affects dynamic vectorcardiographic ischemia monitoring parameters.

AIMS: The present study was undertaken to assess the role of isolated ultrafiltration (UF phase) and hemodialysis with minimal ultrafiltration (HD phase) in changes in parameters reflecting myocardial ischemia: QRS vector difference (QRS-VD), ST change vector magnitude (STC-VM) and ST vector magnitude (ST-VM6) registered by MIDA (myocardial infarction dynamic analysis). PATIENTS AND METHODS: Twelve patients on maintenance hemodialysis were first ultrafiltrated for 2.5 h without dialysis (UF) followed by a 2.5-hour session of hemodialysis with minimal ultrafiltration (HD). Computerized vectorcardiography (VCG) was used for on-line dynamic analysis of ST segment and QRS complex changes. Blood volume (BV) changes were monitored non-invasively and continuously with the CRIT-LINE instrument. Whole-body bioelectric impedance analysis (BIA) was used for extracellular water (ECW) estimation. RESULTS: During the UF phase QRS-VD and STC-VM showed a statistically significant increasing linear trend (time effect for both QRS-VD and STC-VM p < 0.0001, while no changes were noted in ST-VM6; time effect p = 0.986). During the HD phase none of these parameters changed (time effect for QRS-VD p = 0.855, for STC-VM p = 0.275 and for ST-VM6 p = 0.976). During the UF, phase changes in QRS-VD were in close relation to those in ECW. CONCLUSION: Isolated ultrafiltration leads to an increase in the VCG ischemia monitoring parameters QRS-VD and STC-VM. The increase of QRS-VD is related to changes in ECW. Hemodialysis with minimal ultrafiltration has no effect on VCG ischemia monitoring parameters.

Adult↗

PubMed2001

ST-segment level and slope in exercise-induced myocardial ischemia evaluated with body surface potential mapping.

Body surface potential mapping (BSPM) is superior to 12-lead electrocardiography for detection of acute and old myocardial infarctions (MIs). We used BSPM to examine electrocardiographic criteria for acute reversible myocardial ischemia. BSPM with 123 channels was performed in 45 patients with coronary artery disease (CAD) and 25 healthy controls during supine bicycle exercise testing. Of the 45 patients, 18 patients had anterior, 14 had posterior, and 13 had inferior ischemia documented by coronary angiography and thallium scintigraphy. The ST amplitude was measured 60 ms after the J-point and the ST slope calculated by fitting a regression line from the J-point to 60 ms after it. The optimal locations for detecting ST depression and ST-slope decrease were identified. In the pooled CAD patient group, the optimal location for ST depression was 5 cm below standard lead V(5) (CAD group: -70 +/- 70 microV; controls: 70 +/- 80 microV, p <0.001). Using a cut-off value of -10 microV, the ST depression separated the patients with CAD from controls with a sensitivity of 84% and a specificity of 96%. The ST slope became more horizontal in the patient group than in the control group. The optimal location for ST-slope decrease was over the left side (CAD group: 20 +/- 20 microV/s; controls: 720 +/- 320 microV/s, p <0.001). Using a cut-off value of 320 microV/s, the ST slope separated patients with CAD from controls with a sensitivity of 93% at a specificity level of 88%. The area under the receiver operating characteristic curve of ST slope tended to be higher than the one of ST depression (97% vs 93%; p = 0.097). In conclusion, regions sensitive for ST depression and for ST-slope decrease could be identified in BSPM, despite variation in the location of ischemia and the presence or absence of a history of MI. ST slope is a sensitive and specific marker of transient myocardial ischemia, and might perform even better than ST depression.

Body Surface Potential Mapping↗

PubMed2001

Indoor radon concentrations caused by construction materials in 23 workplaces.

The aim of this study was to compare the measured and the calculated concentrations of indoor radon caused by building materials at 23 workplaces. The measured concentrations of radon were clearly higher than the calculated radon concentrations from the building materials, which indicated that the main source of indoor radon was the soil under and around the buildings. The highest means of continuously (933 Bq m(-3)) and integrated (169 Bq m(-3)) measured and calculated (from 70 to 169 Bq m(-3)) concentrations of radon were found in hillside locations. On the other hand, the median (27 and 43 Bq m(-3)) and maximum (626 and 1002 Bq m(-3)) values of calculated indoor radon concentrations exhaled from construction materials were the highest at the ground level places. On average, only 7-19% of the radon seemed to originate from the construction materials.

Air Pollution, Indoor↗

PubMed2001

Recording locations in multichannel magnetocardiography and body surface potential mapping sensitive for regional exercise-induced myocardial ischemia.

INTRODUCTION: This study aimed to identify the optimal locations in multichannel magnetocardiography (MCG) and body surface potential mapping (BSPM) to detect exercise-induced myocardial ischemia. METHODS: We studied 17 healthy controls and 24 coronary artery disease (CAD) patients with stenosis in one of the main coronary artery branches: left anterior descending (LAD) in 11 patients, right (RCA) in 7 patients, and left circumflex (LCX) in 6 patients. MCG and BSPM signals were recorded during a supine bicycle stress test. The capability of a recording location to separate the groups was quantified by subtracting the mean signal amplitude of the normal group from that of the patient group during the ST segment and at the T-wave apex, and dividing the resulting amplitude difference by the corresponding standard deviation within all subjects. RESULTS: In MCG the optimal location for ST depression was at the right inferior grid for the RCA, at the mid-inferior grid for the LCX, and in the middle of these locations for the LAD subgroup (mean ST amplitudes: CAD -80 +/- 360fT, controls 610 +/- 660fT; p < 0.001). In BSPM it was on the left upper anterior thorax for the LAD, left lower anterior thorax for the RCA, and on the lower back for the LCX subgroup (mean ST amplitudes: CAD -39 +/- 61 microV and controls 38 +/- 38 microV; p < 0.001). In MCG the optimal site for T-wave amplitude decrease was the same as the one for the ST depression. In BSPM it was on the middle front for the LAD, on the back for the LCX and on the left abdominal area for the RCA group. In accordance with electromagnetic theory, the largest ST segment and T-wave amplitude changes took place in MCG in locations orthogonal to those in BSPM. CONCLUSION: This study identified magnetocardiographic and BSPM recording locations which are sensitive for detecting transient myocardial ischemia by evaluation of the ST segment as well as the T-wave. These locations strongly depend on ischemic regions and are outside the conventional 12-lead ECG recording sites.

Aged↗

PubMed2001

Flavonol and flavone intake and the risk of cancer in male smokers (Finland).

OBJECTIVE: To study the associations between the intake of flavonols and flavones and the risk of cancer. METHODS: The study cohort consisted of 27,110 male smokers, aged 50-69 years, without history of cancer. They were participants of the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study in Finland. The men completed a validated dietary questionnaire at baseline. Incident cases of cancers were identified through national registers. During an average 6.1-year follow-up, 791 lung cancers, 226 prostate cancers, 156 urothelial cancers, 133 colorectal cancers, 111 stomach cancers, and 92 renal cell cancers were diagnosed. RESULTS: Intake of flavonols and flavones was inversely associated with the risk of lung cancer; multivariate relative risk in the highest vs. the lowest quartile 0.56, 95% confidence interval 0.45-0.69, p for trend 0.0001. The risk was similar in all histological types of lung cancer. No association was found between flavonol and flavone intake and the risk of other cancers. CONCLUSIONS: Intake of flavonols and flavones seemed to be inversely associated with the risk of lung cancer, but not with that of other cancers.

Aged↗

PubMed2001

Magnetocardiographic intra-QRS fragmentation analysis in the identification of patients with sustained ventricular tachycardia after myocardial infarction.

The aim of this study was to investigate if magnetocardiographic (MCG) analysis of cardiac micropotentials within the QRS complex can identity patients prone to ventricular arrhythmias, and to compare it to MCG time-domain, late-field analysis. The study population consisted of 136 patients with remote MI, 53 with and 83 without a history of VT. After averaging and high pass filtering of multichannel MCG signals, time-domain parameters describing the end-QRS activity and fragmentation index M and score S describing the whole QRS complex were computed. Fragmentation and time-domain parameters differed between the VT and control groups: fragmentation index M was 12 +/- 3 versus 9 +/- 2 (P <0.001), fragmentation score S was 83 +/- 42 versus 56 +/- 21 (P < 0.001), and filtered QRS duration was 144 +/- 32 versus 114 +/- 19 ms (P < 0.001) in VT and control groups, respectively. A combination of fragmentation parameters yielded 87% sensitivity and 61% specificity in VT identification. Corresponding figures for a time-domain parameter combination were 81% and 72%. Sensitivity of time-domain analysis was 88% and specificity was 75% in a subgroup with anterior MI. In multivariate analysis, fragmentation and time-domain analyses discriminated VT patients from controls independently of the extent of coronary artery disease or left ventricular dysfunction. MCG in postinfarction patients reveals pathology associated with propensity to ventricular arrhythmias inside and not only at the end of the QRS complex. MCG seems most accurate in the anterior infarct location.

Aged↗

PubMed2001

Insulin-like growth factor binding protein 5 and type-1 insulin-like growth factor receptor are differentially regulated during apoptosis in cerebellar granule cells.

Neuronal apoptosis is considered to play a significant role in several neuropathological conditions. However, the molecular mechanisms underlying neuronal apoptosis are poorly understood. Insulin-like growth factor (IGF) signalling is considered to be an important regulator of neuronal differentiation, survival and apoptosis. We have examined the expression of two members of the IGF system, insulin-like growth factor binding protein 5 (IGFBP-5) and the type-1 IGF receptor (IGF1R), during apoptosis of rat cerebellar granule cells (CGCs) in vitro. We describe a prominent downregulation of IGFBP-5 mRNA and protein expression. We also show that IGF-I increases IGFBP-5 expression in CGCs and that the downregulation of IGFBP-5 mRNA can be suppressed by inhibiting mRNA synthesis with actinomycin D. The expression of IGF1R mRNA showed a transient upregulation during potassium chloride (KCl) deprivation induced apoptosis, in contrast to the IGF1R protein level, which was downregulated during KCl deprivation. Our results provide insight into the expression of IGF-related genes during neuronal apoptosis, and indicate that they mediate a protective response to the withdrawal of trophic stimulation. It seems that the expression of IGFBP-5 and IGF1R is regulated to maximize the availability of IGF and the activity of IGF-triggered survival signalling.

Animals↗

PubMed2001

Repolarization abnormalities detected by magnetocardiography in patients with dilated cardiomyopathy and ventricular arrhythmias.

INTRODUCTION: Abnormal repolarization is one of the acknowledged mechanisms leading to malignant ventricular arrhythmias. We used a novel magnetocardiographic technique to investigate the role of inhomogeneous repolarization in patients with nonischemic dilated cardiomyopathy prone to sustained ventricular arrhythmias. METHODS AND RESULTS: Forty-nine dilated cardiomyopathy patients were studied, 18 with a history of sustained ventricular tachycardia (n = 6) or ventricular fibrillation (n = 12) and 31 with no ventricular arrhythmias. The magnetocardiogram was registered and QT apex and QT end intervals were determined by a computer algorithm. Inhomogeneity of repolarization was characterized with indices describing QT apex and QT end dispersion, and T wave end duration. In addition, time-domain late fields of the QRS complex in magnetocardiography and QT dispersion in 12-lead ECG were determined. T wave end was longer in the arrhythmia group in patients with sinus rhythm (87 +/- 15 msec vs 73 +/- 12 msec; P = 0.005) and in those not having bundle branch block. Magnetocardiographic late fields of the QRS complex were not different between groups. QT apex and end dispersion on magnetocardiography or 12-lead ECG showed no difference. CONCLUSION: Prolongation of the end part of the T wave revealed by magnetocardiography is related to malignant ventricular arrhythmias in dilated cardiomyopathy. The results suggest that abnormal repolarization rather than delayed conduction underlies the arrhythmias in this disease.

Adult↗

PubMed2001

Postmyocardial infarction patients susceptible to ventricular tachycardia show increased T wave dispersion independent of delayed ventricular conduction.

INTRODUCTION: Experimentally, both delayed ventricular conduction and nonhomogeneous ventricular repolarization contribute to reentrant arrhythmias. We tested the hypothesis that increased T wave dispersion is independent of delayed ventricular conduction associated with arrhythmia vulnerability in postmyocardial infarction (post-MI) patients. METHODS AND RESULTS: We studied 32 post-MI patients with clinical or inducible monomorphic ventricular tachycardia (VT group), 28 post-MI patients without arrhythmias (MI group), and 13 healthy controls, using magnetocardiographic (MCG) mapping with signal averaging. Twelve-lead ECG was the reference. Filtered QRS duration (fQRS) and T wave peak to T wave end interval (TPE) were used as measures of ventricular conduction and nonhomogeneity in ventricular repolarization, respectively. In MCG, the VT group showed the longest fQRS (135+/-34 msec vs 114+/-22 msec in the MI group; P = 0.012). Mean TPE and maximum TPE in VT versus MI groups were 78+/-9 msec versus 70+/-6 msec (P < 0.001) and 117+/-23 msec versus 104+/-19 msec (P = 0.020), respectively. Maximum TPE did not correlate with fQRS in the VT group (r = 0.063; P = NS) but did correlate in the MI group (r = 0.396; P = 0.037). For identification of post-MI patients prone to VT, selection of cutoff values for fQRS >140 msec and mean TPE >81 msec gave sensitivity and specificity of 41% and 89%, and 31% and 96%, respectively. Their combination increased sensitivity to 63% while maintaining 89% specificity. CONCLUSION: Post-MI patients susceptible to VT show increased T wave dispersion independent of delayed ventricular conduction.

Aged↗

PubMed2000

Expression of transcriptional repressor proteins mSin3A and 3B during aging and replicative senescence.

Sin3 proteins have a key role in transcriptional repression mediated by histone deacetylation. Mammalian Sin3 proteins, mSin3A and 3B, act as adapter molecules which bind both to repressive transcription factors and to the methyl-CpG-binding proteins (MeCPs) and recruit histone deacetylases to assemble a multiprotein repressor complex. We have recently observed (Biochem. Biophys. Res. Commun. 252, 274-277, 1998) that the expression of mSin3A but not mSin3B protein is induced during neuronal apoptosis. The purpose of this study was to find out whether aging and replicative senescence affect the expression levels of mSin3A and 3B repressor proteins. We studied the expression levels of mSin3A and 3B mRNAs and proteins both in replicative senescence model of WI-38 fibroblasts and in liver and brain tissues of young (4-6 months) and old (26-30 months) male Wistar rats. Replicative senescence of human WI-38 fibroblasts did not affect the expression levels of mSin3A and 3B mRNAs. However, the late passage WI-38 fibroblasts showed a significant decline in the expression level of mSin3A protein. Immortalization of WI-38 fibroblasts with SV-40 transformation increased the expression level of 6.0 kb mSin3A mRNA. Aging of Wistar rats did not affect the expression levels of either mSin3A or mSin3B mRNAs in the liver and frontal cortex. Similarly, the protein levels of mSin3A and 3B were unaffected in the hippocampus, cerebellum and liver tissues during aging. These results show that aging in vivo, in contrast to replicative senescence, does not affect the expression levels of mSin3A and 3B repressor proteins. However, this does not exclude the possible age-related functional changes mediated by mSin3-histone deacetylase complexes.

Animals↗

PubMed2000

Magnetocardiographic QT dispersion during cardiovascular autonomic function tests.

QT dispersion is considered to reflect nonhomogeneity of ventricular repolarization. The autonomic nervous system modulates QT interval duration, but the effect may not be spatially homogenous. Magnetocardiography (MCG) registers the weak magnetic fields generated by myocardial electric currents with high localizing accuracy. We studied the effects of rapid cardiovascular autonomic nervous adjustment on QT dispersion in MCG. Ten healthy male volunteers were monitored during deep breathing, the Valsalva maneuver, sustained handgrip, hyperventilation, the cold pressor test and mental stress. 67 MCG channels and 12 ECG leads were recorded simultaneously. A computer algorithm was used for QT interval measurements. QT dispersion was defined as maximum - minimum or standard deviation of the QTpeak and QTend intervals. In MCG the QT(end) dispersion increased during deep inspiration compared with deep expiration (96+/-19 ms v. 73+/-27 ms, p = 0.05). Magnetic QT dispersion tended to increase during the bradycardia phase of the Valsalva maneuver, but the change was obvious only for QT(end) (55+/-26 ms v. 76+/-29 ms, p<0.05). Other tests had no significant effect on QT dispersion, not even the cold pressor test, although it causes strong sympathetic activation. Magnetic and electric QT(peak) and QT(end) intervals correlated closely (r = 0.93 and 0.91), whereas the QT dispersion measures showed no correlation. In conclusion, magnetic QT dispersion is not modified by rapid changes in autonomic tone, but maneuvers involving deep respiratory efforts and changes in ventricular loading affect QT dispersion measurements.

Adult↗

PubMed2000

Vitamin A and infant mortality: beyond intention-to-treat in a randomized trial.

This paper investigates the effect of one dose of vitamin A on subsequent 4 month mortality in children under 6 months of age in a randomized, double-blind placebo-controlled community trial in Nepal. An earlier published intention-to-treat analysis showed no benefit, but ignored the information on actual receipt of treatment. Structural failure time models (Robins and Tsiatis, '91) use randomization based inference and incorporate compliance information which is possibly selective. The data presented here offer some new challenges for this approach: ward-based randomization induces correlation between survival outcomes; and the actual receipt of vitamin A dose is not always recorded. To tackle the problem of the clustered survival data we consider a robust version of the structural parameter vector estimator. A sensitivity analysis captures boundaries for the estimated structural parameters reflecting a range of potential values of children whose true receipt of treatment is unknown. The analysis suggests that the effect of vitamin A was beneficial in the beginning of the trial but towards the end of the trial there was a reversal of this effect.

Double-Blind Method↗

PubMed2000

Effects of cardiovascular autonomic function tests on QT dispersion in the 12-lead electrocardiogram of healthy patients.

Changes in autonomic tone modulate QT interval duration. How cardiovascular autonomic reflexes affect QT dispersion, a suggested marker of arrhythmia risk, is not well established. We studied 10 healthy young adult volunteer men during quiet and deep breathing, the Valsalva maneuver, sustained handgrip, hyperventilation, the cold pressor test, and mental stress. An automated method was used for measurement of QT-peak and QT-end intervals, and QT dispersion was defined as maximum-minimum of the measured intervals. QT-peak dispersion was greater on deep expiration than deep inspiration (49 +/- 20 ms vs 37 +/- 14 ms, P < .05). QT-end dispersion decreased in the tachycardia phase of the Valsalva maneuver (45 +/- 23 ms vs 35 +/- 21 ms, P < .05), but QT dispersion did not change during the other interventions. Rapid cardiovascular autonomic reflex adjustment does not change QT dispersion in healthy young adult men. However, large intrathoracic volume and intrathoracic pressure changes during forced respiratory movements might confound QT dispersion measurements.

Adult↗

PubMed2000

Late fields of the magnetocardiographic QRS complex as indicators of propensity to sustained ventricular tachycardia after myocardial infarction.

INTRODUCTION: Magnetocardiographic (MCG) mapping is a new method to record cardiac signals. This study examined the association of MCG late fields with the propensity to sustained ventricular tachycardia (VT) after myocardial infarction (MI). METHODS AND RESULTS: One hundred patients with remote MI were studied, 38 with and 62 without history of VT. High-resolution MCG and signal-averaged ECG (SAECG) as a comparative method were recorded. Time-domain parameters describing the abnormal low-amplitude end QRS activity, MCG late fields, and SAECG late potentials were analyzed. Late field parameters differed significantly between the patient groups: filtered QRS duration was 137 +/- 26 msec in the VT group and 110 +/- 18 msec in the control group (P < 0.001), and root mean square amplitude of the last 40 msec was 260 +/- 170 and 510 +/- 360 fT (P < 0.001), respectively. The optimal MCG parameter combination yielded a sensitivity of 92% and a specificity of 61% in classification to the VT group, whereas those for SAECG were 63% and 66%. In a subgroup of 63 patients with marked left ventricular dysfunction and comparable stage of coronary heart disease, only MCG (sensitivity 73%, specificity 67%) but not SAECG could assign a patient to the VT group. CONCLUSION: Late fields of the MCG QRS complex indicate propensity to life-threatening arrhythmias in post-MI patients. This discriminative ability persists in the presence of severe left ventricular dysfunction where ECG late potentials lose their informative value. MCG late field analysis is a potential new method for noninvasive risk assessment in post-MI patients.

Electrocardiography↗

PubMed2000

Intake of flavonoids, carotenoids, vitamins C and E, and risk of stroke in male smokers.

BACKGROUND AND PURPOSE: Antioxidants may protect against atherosclerosis and thus prevent cerebrovascular disease. We studied the association between dietary antioxidants and subtypes of stroke. METHODS: The study cohort consisted of 26 593 male smokers, aged 50 to 69 years, without a history of stroke. They were participants of the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study in Finland. The men completed a validated dietary questionnaire at baseline. Incident cases were identified through national registers. RESULTS: During a 6.1-year follow-up, 736 cerebral infarctions, 83 subarachnoid hemorrhages, and 95 intracerebral hemorrhages occurred. Neither dietary flavonols and flavones nor vitamin E were associated with risk for stroke. The dietary intake of beta-carotene was inversely associated with the risk for cerebral infarction (relative risk [RR] of highest versus lowest quartile 0.74, 95% CI 0.60 to 0. 91), lutein plus zeaxanthin with risk for subarachnoid hemorrhage (RR 0.47, 95% CI 0.24 to 0.93), and lycopene with risks of cerebral infarction (RR 0.74, 95% CI 0.59 to 0.92) and intracerebral hemorrhage (RR 0.45, 95% CI 0.24 to 0.86). Vitamin C intake was inversely associated with the risk for intracerebral hemorrhage (RR 0.39, 95% CI 0.21 to 0.74). After simultaneous modeling of the antioxidants, a significant association remained only between beta-carotene intake and risk for cerebral infarction (RR 0.77, 95% CI 0.61 to 0.99). CONCLUSIONS: Dietary intake of beta-carotene was inversely associated with the risk for cerebral infarction. No association was detected between other dietary antioxidants and risk for stroke.

Aged↗

PubMed2000

Hemodialysis causes changes in dynamic vectorcardiographic ischemia monitoring parameters.

AIMS: The aim of this study was to establish whether changes in parameters reflecting myocardial ischemia QRS vector difference (QRS-VD), ST change vector magnitude (STC-VM) and ST vector magnitude (ST-VM6) during hemodialysis (HD) registered by MIDA (myocardial infarction dynamic analysis) are related to changes in blood volume (BV), extracellular water (ECW) and blood biochemistry. PATIENTS AND METHODS: Fifteen hemodialysis (HD) patients were studied. Computerized vectorcardiography was used for on-line dynamic analysis of ST segment and QRS complex changes. BV changes were monitored non-invasively and continuously with the CRIT-LINE instrument. Bioelectric impedance analysis (BIA) was used for ECW estimation. Blood samples were taken before and after hemodialysis for hemoglobin (B-Hb), hematocrit (B-Hcr), sodium (P-Na), chloride (P-Cl), magnesium (P-Mg), potassium (P-K), ionized calcium (P-iCa), phosphate (P-Pi) and astrup measurement. RESULTS: During dialysis treatment QRS-VD, ST-VM6 and STC-VM did not change in parallel. According to the linear mixed model, no statistically significant changes were noted in ST-VM6 during dialysis (time effect p = 0.5635). On the other hand, QRS-VD and STC-VM showed a statistically significant linear trend (time effect for QRS-VD p = 0.0001 and for STC-VM p = 0.0004). Changes in both ECW and BV affected the change in QRS-VD and in STC-VM. CONCLUSION: During HD treatment changes in the vectorcardiographic ischemia monitoring parameters QRS-VD and STC-VM are mostly related to ECW and BV changes and may give a false positive impression of myocardial ischemia. The ST-VM6 trend is less markedly influenced by volume changes.

Adult↗

PubMed1999

Regulation of PTEN expression in neuronal apoptosis.

PTEN phosphatase is a tumor suppressor gene that dephosphorylates phosphatidylinositol phosphates. PTEN restrains the function of a major antiapoptotic and survival pathway involving phosphoinositide 3-kinase and Akt kinase. Our purpose was to find out whether apoptotic inducers affect the expression of PTEN in cerebellar granule neurons and neuroblastoma 2a cells (Neuro-2a). PTEN mRNA expression showed a major 5.5-kb and a lower abundance 2.5-kb transcripts. In Neuro-2a cells, serum withdrawal induced a prominent, continuous decrease both in 5.5- and 2.5-kb transcripts of PTEN mRNA. Simultaneously, the expression level of 56-kDa PTEN protein decreased in Neuro-2a cells. The decrease in PTEN expression precedes apoptotic changes observed after serum withdrawal. On the contrary, okadaic acid and etoposide only slightly affected the expression of PTEN although they induce a prominent apoptosis in Neuro-2a cells. In cerebellar granule neurons, okadaic acid treatment induced a prominent increase in PTEN mRNA expression after 6-h treatment, both at the 5.5- and 2.5-kb transcripts. The early response in PTEN mRNA expression disappeared in 5.5-kb transcripts already at 12 h and in the case of 2.5-kb transcripts it lasted up to 24 h. Potassium deprivation, known to induce apoptosis in cerebellar granule cells, did not affect PTEN mRNA expression but together with serum deprivation induced a clear decrease in the 5. 5-kb PTEN transcripts. It seems that the changes in PTEN expression level and neuronal apoptosis are not related to each other in general but the expression of PTEN phosphatase seems to regulate certain apoptotic signals affecting phosphoinositide 3-kinase function.

Animals↗