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Biomedical subjects

A Antoniadis

Publications and source records attributed to A Antoniadis.

At least 19 recordsLinked to original sources
PubMed2000

Acute endothelin-A receptor antagonism prevents normal reduction of myocardial ischemia on repeated balloon inflations during angioplasty.

BACKGROUND: Myocardial ischemia and reperfusion are associated with increased production of endothelin (ET)-1. METHODS AND RESULTS: We examined the effects of BQ-123, a selective ET(A) receptor antagonist, in 80 patients. All patients were randomly allocated to an intracoronary infusion of saline or BQ-123 (6 micromol/L over 20 minutes). The reference group consisted of 20 patients undergoing coronary angiography. BQ-123 produced a 10% (P:<0.005) increase in distal coronary artery diameter. The main study group consisted of 30 patients undergoing coronary angioplasty. All patients underwent a minimum of 3 balloon inflations (BIs). Surface and intracoronary electrocardiographic ST-segment shift as well as pain score were recorded at the end of each BI. BQ-123 or saline was given by intracoronary infusion between the second and the third BI in random allocation. In the saline group, intracoronary ST-elevation decreased from 1.26+/-0.55 mV during the first BI to 0.77+/-0.56 mV during the third BI (P:<0.05) and the surface ST elevation decreased from 0.20+/-0.15 to 0.10+/-0.07 mV (P:<0.05). In the BQ-123 group, the respective values were 1.22+/-0.48 mV and 1.13+/-0.62 mV (intracoronary) and 0.17+/-0.18 and 0.17+/-0.21 mV (surface) (both P:=NS). The decrease in pain score was significantly higher in the saline group (F:=5.97, P:=0.004). In 30 patients (collateral circulation group), the angioplasty protocol was repeated with the use of a pressure guide wire. BQ-123 produced a significant (F:=3.30, P:=0.04) decrease in coronary wedge pressure. CONCLUSIONS: Acute ET(A) receptor antagonism prevents the normal reduction of myocardial ischemia on repeated BIs during angioplasty. This may be explained by a "steal" effect through coronary collaterals.

Angioplasty, Balloon, Coronary↗
PubMed2000

Brain natriuretic peptide increases acutely and much more prominently than atrial natriuretic peptide during coronary angioplasty.

BACKGROUND: Increased levels of plasma brain natriuretic peptide (BNP) are observed in patients with congestive heart failure, hypertension, left ventricular hypertrophy, and acute myocardial infarction. However, there are no data on serial changes in plasma levels of BNP in patients undergoing coronary angioplasty. HYPOTHESIS: The study was undertaken to examine plasma concentrations of BNP together with those of atrial natriuretic peptide (ANP) in patients undergoing percutaneous transluminal coronary angioplasty (PTCA). METHODS: Plasma concentrations of BNP and ANP were examined in 13 patients with stable angina pectoris and good left ventricular function undergoing PTCA. Blood samples were taken from the femoral vein at baseline, after the first balloon inflation, after the end of the procedure, and 4 h thereafter. RESULTS: Plasma BNP levels were 14 +/- 4 at baseline, 22 +/- 10 after the first balloon inflation, 28 +/- 12 at the end of the procedure, and 15 +/- 4 pgr/ml 4 h thereafter (F = 13.05, p < 0.00001). Plasma ANP levels were 80 +/- 15, 86 +/- 14, 90 +/- 24, and 75 +/- 6 fmol/l (F = 5.95, p = 0.002), respectively. The increase of BNP at the end of the procedure was related to the increase of ANP (r = 0.78, p = 0.002). CONCLUSION: Plasma BNP levels increase acutely and much more prominently than those of plasma ANP during coronary angioplasty; however, plasma BNP levels return to baseline values shortly after the end of the procedure.

Angina Pectoris↗
PubMed2000

Combined treatment of hypercholesterolemia of renal transplant allograft recipients with fluvastatin and gemfibrozil.

The aim of this study was to investigate the safety and efficacy of combined treatment with fluvastatin (F) and gemfibrozil (G) in hypercholesterolemic renal transplant recipients (RTR). Ten hypercholesterolemic (total cholesterol [TC] > 220 mg/dl) RTR (7 men) with mean age 44 years (range 25-56 years) who remained hypercholesterolemic after 3 months of treatment (period A) with fluvastatin (40 mg/d) continued taking the same dose of F plus G (600 mg/dl) for another 3-month period (B). Serum total cholesterol, high density lipoprotein cholesterol (HDL-C), LDL cholesterol (LDL-C), triglyceride, serum creatinine (creatinine phosphokinase (CPK), serum glutamic-oxaloacetic transaminase (SGOT), and serum glutamate pyruvate transaminase (SGPT) were measured before treatment and at the end of periods A and B. Mean TC levels were 360.30 +/- 62.42 mg/dl, 324.10 +/- 100.53 mg/dl, 270.80 +/- 67.77 mg/dl; mean LDL-C levels were 259.33 +/- 71.43 mg/dl, 219.60 +/- 81.31 mg/dl, 189.70 +/- 65.51 mg/dl; mean HDL-C levels were 37.10 +/- 11.68 mg/dl, 39.80 +/- 13.21 mg/dl, 41.00 +/- 12.94 mg/dl; mean triglyceride levels were 354.60 +/- 183.29 mg/dl, 349.30 +/- 242.94 mg/dl, 207.00 +/- 85.35 mg/dl before treatment and at the end of periods A and B, respectively. There was a statistically significant fall of serum TC (P = 0.002), LDL-C (P = 0.016), and triglyceride (P = 0.029) levels at the end of periods A and B. Kidney and liver function did not change. F and G combined treatment is safe and useful in patients who do not respond satisfactorily to monotherapy with F. Gemfibrozil augments the effect of F on TC, LDL-C, and triglyceride levels.

Adult↗
PubMed2000

Genetic heterogeneity of HIV-1 in Greece.

The aim of this study was to detect and determine the genetic variation of HIV-1 in Greece and to analyze the phylogenetic relationships and transmission dynamics of identified variants. Eighty-six blood samples from HIV-1 seroconverted patients of different risk groups were collected from the AIDS clinic, AHEPA Hospital, Thessaloniki, Greece. Retroviral DNA was extracted from uncultured peripheral blood mononuclear cells. HIV-1 DNA sequences encoding a 500-bp fragment of the gp120 C2-C3 region were amplified from each study subject, and they were genetically subtyped by heteroduplex mobility assay and DNA sequencing. Genetic distances and phylogenetic relationships of DNA sequences were estimated using PHYLIP software. Our results revealed that 82 out of 86 (95.3%) subjects carried subtype B sequences, while four (4.7%) carried subtype A sequences. Subtype A in Greek individuals not having traveled abroad was documented. An average of intrasubtype B genetic divergence of 15% was noted. Our findings demonstrate the presence of at least two genetic subtypes of HIV-1 in northern Greece--subtype B and subtype A. The predominant subtype is subtype B, which was transmitted into Greece by multiple sources. Our observations lend support to the argument that the distribution of HIV-1 subtypes is determined by founder effects or other processes rather than any tropism for particular cell types or mode of transmission.

Adult↗
PubMed2000

Outbreak of infections in a Greek university hospital involving a single clone of high-level aminoglycoside-resistant Enterococcus faecalis.

Among 145 Enterococcus faecalis isolates recovered during a 15-month period (April 1997-June 1998) in AHEPA University Hospital, Thessaloniki, Greece, 94 (65%) exhibited high-level resistance to gentamicin or streptomycin and 61 (42%) to both aminoglycosides; 73% of the high-level aminoglycoside-resistant E. faecalis isolates belonged to a single clone carrying the gene aac(6')-Ie-aph(2")-Ia. These findings differ from those of other regions, where high-level aminoglycoside-resistance genes are dispersed into genetically unrelated strains.

Aminoglycosides↗
PubMed2000

Pheromone responses and high-level aminoglycoside resistance of conjugative plasmids of Enterococcus faecalis from Greece.

Fifteen of 22 clinical isolates of Enterococcus faecalis with high-level aminoglycoside resistance isolated in Greece, which were tested for mating ability, co-transferred pheromone response genes together with aminoglycoside resistance determinants to a sensitive recipient strain. Nine of them belonged to the same pulsotype, while the remaining six isolates were genetically unrelated. The prgB gene, which encodes aggregation substance, was detected in all the clinical isolates and transconjugants by both PCR and DNA hybridization but prgA, which encodes the surface exclusion protein, was only detected in two isolates, whereas it is present in most pheromone response plasmids from other sources.

Aminoglycosides↗
PubMed2000

Relation between heart rate variability and training load in middle-distance runners.

PURPOSE: Monitoring physical performance is of major importance in competitive sports. Indices commonly used, like resting heart rate, VO2max, and hormones, cannot be easily used because of difficulties in routine use, of variations too small to be reliable, or of technical challenges in acquiring the data. METHODS: We chose to assess autonomic nervous system activity using heart rate variability in seven middle-distance runners, aged 24.6 +/- 4.8 yr, during their usual training cycle composed of 3 wk of heavy training periods, followed by a relative resting week. The electrocardiogram was recorded overnight twice a week and temporal and frequency indices of heart rate variability, using Fourier and Wavelet transforms, were calculated. Daily training loads and fatigue sensations were estimated with a questionnaire. Similar recordings were performed in a sedentary control group. RESULTS: The results demonstrated a significant and progressive decrease in parasympathetic indices of up to -41% (P < 0.05) during the 3 wk of heavy training, followed by a significant increase during the relative resting week of up to +46% (P < 0.05). The indices of sympathetic activity followed the opposite trend, first up to +31% and then -24% (P < 0.05), respectively. The percentage increasing mean nocturnal heart rate variation remained below 12% (P < 0.05). There was no significant variation in the control group. CONCLUSION: This study confirmed that heavy training shifted the cardiac autonomic balance toward a predominance of the sympathetic over the parasympathetic drive. When recorded during the night, heart rate variability appeared to be a better tool than resting heart rate to evaluate cumulated physical fatigue, as it magnified the induced changes in autonomic nervous system activity. These results could be of interest for optimizing individual training profiles.

Adult↗
PubMed2000

HIV-1 co-receptor CCR5 and CCR2 mutations among Greeks.

The frequency of CCR5 and CCR2 alleles in human immunodeficiency virus (HIV)-positive and HIV-negative populations of Northern Greece was investigated. The frequency of the CCR5Delta32 allele among the HIV-negative subjects was 0.052, while it was approximately two-fold lower among the seropositives, suggesting that the heterozygous genotype confers a partial resistance to the HIV infection. No significant difference in CCR2 allele frequency between the two groups was observed.

Alleles↗
PubMed2000

Endogenous endothelin maintains coronary artery tone by endothelin type A receptor stimulation in patients undergoing coronary arteriography.

OBJECTIVE: To examine the contribution of endothelin type A (ET(A)) receptor stimulation by endogenously generated endothelin-1 (ET-1) to the maintenance of coronary vascular tone in humans. DESIGN: Controlled clinical study. SETTING: Tertiary cardiovascular referral centre. PATIENTS: 14 subjects were studied, seven with normal coronary arteries and seven with coronary artery disease, mean (SEM) age, 53 (2) years. INTERVENTIONS: After diagnostic coronary arteriography, BQ-123 (a selective ET(A) receptor antagonist; 100 nmol/min) in 0.9% saline, was infused into the left coronary artery at a rate of 1 ml/min for 60 minutes. Eight control subjects received saline alone. MAIN OUTCOME MEASURES: Blood flow velocity in the left anterior descending coronary artery, measured using a Doppler flow guidewire; coronary arteriography performed at baseline and immediately at the end of the BQ-123 or saline infusion to measure the diameter of proximal and distal left anterior descending coronary artery segments. RESULTS: The diameter of the proximal segment increased by 6 (2)%, while that of the distal segment increased by 12 (3)% after BQ-123 (both p < 0.05 v baseline). Coronary blood flow increased from 75 (10) to 92 (10) ml/min and coronary vascular resistance decreased from 1.99 (0.36) to 1.44 (0. 22) mm Hg/ml/min after BQ-123 (both p < 0.05 v baseline). The response to BQ-123 of patients with and without coronary artery disease was similar. There was no effect of saline in the controls. CONCLUSIONS: Endogenously produced ET-1 contributes to the maintenance of basal coronary artery tone in humans by ET(A) receptor stimulation. The role of ET(B) receptors remains to be defined.

Blood Flow Velocity↗
PubMed1999

Intracoronary ketanserin augments coronary collateral blood flow and decreases myocardial ischemia during balloon angioplasty.

AIMS: To test the hypothesis that ketanserin augments coronary collateral blood flow and decreases myocardial ischemia during balloon angioplasty. METHODS AND RESULTS: Forty-four patients with single vessel disease and stable angina were studied. Collateral flow was determined during balloon inflations, based on the distal velocity time integral (13 patients) or on coronary wedge/mean arterial pressure measurements (10 patients). The 2nd and 3rd inflations lasted the same time and between them 1.5 mg intracoronary ketanserin in 10 ml normal saline was administered over 3 min. In 21 control subjects normal saline alone was given. In the flow velocity group the velocity time integral was 78.5+/-53.1 mm during the 2nd inflation and 106.0+/-43.2 mm during the 3rd (p<.05), while the ST deviation was 1.1+/-.7 and .7+/-.7 mm, respectively (p<.05). In the intracoronary pressure group the CWP/MBP was .40+/-.10 during the 2nd inflation and .45+/-.11 during the 3rd (p<.05), while the ST deviation was 1.2+/-.8 and .8+/-.8 mm respectively (p<.05). In the controls no variables changed during the tested inflations. CONCLUSION: Intracoronary administration of ketanserin augments coronary collateral flow and decreases myocardial ischemia during balloon angioplasty. This could be of clinical significance in the management of acute ischemic syndromes.

Angioplasty, Balloon↗
PubMed1999

In-vitro activity of antibiotics against Legionella pneumophila isolates from water systems.

The activity of five antibiotics was tested against 82 isolates of Legionella pneumophila obtained from water systems in nine European countries. All isolates were susceptible to clarithromycin (MICs 0. 03-0.5 mg/L), erythromycin (MICs 0.125-2.0 mg/L), ciprofloxacin (MICs 0.06-0.25 mg/L), pefloxacin (MICs 0.06-0.5 mg/L) and rifampicin (MICs < or = 0.007-0.015 mg/L). It seems that antibiotics used for legionellosis continue to exhibit good activity against L. pneumophila isolates from environmental sources in European countries.

Anti-Bacterial Agents↗
PubMed1999

Wavelet transform to quantify heart rate variability and to assess its instantaneous changes.

Heart rate variability is a recognized parameter for assessing autonomous nervous system activity. Fourier transform, the most commonly used method to analyze variability, does not offer an easy assessment of its dynamics because of limitations inherent in its stationary hypothesis. Conversely, wavelet transform allows analysis of nonstationary signals. We compared the respective yields of Fourier and wavelet transforms in analyzing heart rate variability during dynamic changes in autonomous nervous system balance induced by atropine and propranolol. Fourier and wavelet transforms were applied to sequences of heart rate intervals in six subjects receiving increasing doses of atropine and propranolol. At the lowest doses of atropine administered, heart rate variability increased, followed by a progressive decrease with higher doses. With the first dose of propranolol, there was a significant increase in heart rate variability, which progressively disappeared after the last dose. Wavelet transform gave significantly better quantitative analysis of heart rate variability than did Fourier transform during autonomous nervous system adaptations induced by both agents and provided novel temporally localized information.

Adrenergic beta-Antagonists↗