Nikolaos Papadopoulos

Prevalence of primary hyperaldosteronism in resistant hypertension: a retrospective observational study.

BACKGROUND Results of several studies published since 1999 suggest that primary hyperaldosteronism (also known as Conns syndrome) affects more than 10% of people with hypertension; however, such a high prevalence has also been disputed. Experts generally agree that resistant hypertension has the highest prevalence of primary hyperaldosteronism, on the basis of small studies. We aimed to assess the prevalence of primary hyperaldosteronism in a large group of patients with resistant hypertension. METHODS Patients with resistant hypertension (blood pressure >140/90 mm Hg despite a three drug regimen, including a diuretic) who attended our outpatient clinic were assessed for primary hyperaldosteronism. Serum aldosterone and plasma renin activity were determined and their ratio was calculated. Patients with a positive test (ratio >65.16 and aldosterone concentrations >416 pmol/L) underwent salt suppression tests with intravenous saline and fludrocortisone. Diagnosis of primary hyperaldosteronism was further confirmed by the response to treatment with spironolactone. FINDINGS Over 20 years, we studied 1616 patients with resistant hypertension. 338 patients (20.9%) had a ratio of more than 65.16 and aldosterone concentrations of more than 416 pmol/L. On the basis of salt suppression tests, 182 (11.3%) patients had primary hyperaldosteronism, and response to spironolactone treatment further confirmed this diagnosis. Hypokalaemia was seen only in 83 patients with primary hyperaldosteronism (45.6%). INTERPRETATION Although the prevalence of primary hyperaldosteronism in patients with resistant hypertension was high, it was substantially lower than previously reported. On the basis of this finding, we could assume that the prevalence of primary hyperaldosteronism in the general unselected hypertensive population is much lower than currently reported. Thus, the notion of an epidemic of primary hyperaldosteronism is not supported.

Glutathione-S-transferase M1 and T1 and cytochrome P1A1 genetic polymorphisms and susceptibility to cervical intraepithelial neoplasia in Greek women.

The aim of the study was to determine the importance of genetic polymorphisms of glutathione-S-transferase T1 and M1 and cytochrome P1A1 genes in the development of cervical intraepithelial neoplasia in Greek women. This was a prospective, case–control study conducted by the Cervical Pathology and Colposcopy Unit of a University Ob/Gyn Department from 1999 to 2003. Cervical smears from 114 controls without any cytological and/or colposcopical evidence of cervical pathology and from 166 women with history of cervical intraepithelial neoplasia (56 CIN I, 54 CIN II and 56 CIN III) were examined with polymerase chain reaction for the above-mentioned genetic polymorphisms, taking also in mind their smoking attitudes. Statistical analysis was performed to detect any association between the null genotype of GSTM1 and GSTT1 genes and the CYP1A1 m1 polymorphism and the severity of cervical intraepithelial neoplasia. The distributions of the GSTT1 and GSTM1 wild-type genotypes were 57.48 and 39.75%, respectively. No woman with homozygous GSTT1 and GSTM1 null/null genotype was identified. CYP1A1 m1 polymorphism frequency was 24.49%. No woman with homozygous CYP1A1 m1/m1 genotype was detected as well. No significant difference in the frequencies of the GSTM1 and GSTT1 null alleles, and the CYP1A1 m1 polymorphism, was found between cases and controls. After application of Mantel–Haenszel χ2 procedure, there was no linear severity of the lesion and the frequency of these polymorphisms. According to our results, glutathione-S-transferase T1 and M1 and cytochrome P1A1 genetic polymporphisms do not appear to be a risk factor for cervical disease irrespective of smoking habits.

HOX A10 and HOX A11 mutation scan in congenital malformations of the female genital tract

Homeobox (HOX) genes encode a number of transcription factors, expressed along the developmental axis of the female genital tract during the embryonic period. Because HOX A10 and HOX A11 genes are expressed in the embryonic paramesonephric (Müllerian) ducts, abnormally low expression by mutant HOX A10 and HOX A11 genes might cause genital tract anomalies. This case-control study examined if one or more mutations in the HOX A10 and HOX A11 genes are included in the pathogenesis of the female genital tract anomalies. Blood samples were obtained from 30 women diagnosed with malformations of the genital tract (18 with septate uterus, three with bicornuate uterus, two with didelphys uterus, two with unicornuate uterus and five with aplasia/dysplasia) and 100 normal controls. DNA samples prepared from blood leukocytes were used as templates for polymerase chain reaction amplification of DNA fragments from HOX A10 and HOX A11 genes. The gene fragments were tested for DNA sequence differences using single-strand conformation polymorphism analysis and sequenced when genetic variation was detected. No subject showed a plausible causative mutation in HOX A10 or HOX A11; the sole variant observed (P38R) found in a patient with septate uterus was also present in her clinically normal mother.

Platelet Activation in Essential Hypertension During Exercise: Pre- and Post-Treatment Changes With an Angiotensin II Receptor Blocker

BACKGROUND Acute exercise may exert deleterious effects on the cardiovascular system through a variety of pathophysiological mechanisms, including increased platelet activation. However, the degree of exercise-induced platelet activation in untreated hypertensive (UH) individuals as compared with normotensive (NT) individuals has yet to be established. Furthermore, the effect of antihypertensive treatment on exercise-induced platelet activation in essential hypertension (EH) remains unknown. METHODS Study 1 consisted of 30 UH and 15 NT subjects. UH subjects who received treatment were included in study 2 and were followed-up after a 3-month treatment period with an angiotensin II receptor blocker (ARB; valsartan). Circulating monocyte-platelet aggregates (MPA) and platelet P-selectin were measured as platelet activation markers at baseline, immediately after a treadmill exercise test, and 10, 30, and 90 minutes later. RESULTS Maximal platelet activation was observed at 10 minutes after peak exercise in both groups. In UH subjects, MPA levels remained increased at 30 minutes after peak exercise, despite BP fall to baseline levels. MPA levels were significantly higher in UH subjects than NT subjects at maximal exercise and at 10 and 30 minutes of recovery. Post-treatment MPA levels increased significantly only at 10 minutes into recovery and were similar to those of NT subjects. CONCLUSIONS Acute high-intensity exercise exaggerates platelet activation in untreated patients with EH compared with NT individuals. Angiotensin II receptor blockade with adequate BP control greatly improves exercise-induced platelet activation in EH. Further studies are needed to clarify whether this phenomenon depends purely on BP lowering or benefits also from the pleiotropic effects of ARBs.

Atypical atrial myxomas in two asymptomatic patients: a case report

BackgroundAtypical cardiac myxomas are a rare occurrence and may present with a variety of clinical manifestations depending on the morphology and location.Case presentationTwo cases of cardiac myxomas atypically located in asymptomatic patients, diagnosed by transthoracic and transoesophageal echocardiography, are presented. In the first case a myxoma is located under the anterior mitral valve leaflet and in the second case a myxoma is located in the right atrium.ConclusionWe emphasize the leading role of transthoracic and transoesophageal echocardiography in the diagnosis of intracavitary cardiac tumours.

Simultaneous Determination of Herbicide Terbuthylazine and Its Major Hydroxy and Dealkylated Metabolites in Typha latifolia L. Wetland Plant Using SPE and HPLC-DAD

Abstract The worldwide application of s-Triazines as herbicides for agricultural and nonagricultural purposes, results in a significant environmental pollution. It is necessary to develop sustainable and environmental friendly techniques in order to remediate surface water from the aforementioned organic substances. Phytoremediation with the wetland plant Typha latifolia L. is a technique that could potentially aid the restoration of polluted surface water. However, there is no analytical method for the determination of terbuthylazine (TER) and its metabolites in Typha latifolia L. and the assessment of the effectiveness of such a procedure. For this reason a method based on high performance liquid chromatography with diode array detection was developed and validated for the simultaneous determination of terbuthylazine (TER) and its major degradation products, desethyl-terbuthylazine, desisopropy-atrazine, hydroxy-terbuthylazine, desethyl-hydroxy-atrazine, and desethyl-hydroxy-terbuthylazine. This method includes both a cleanup and a solid phase extraction step (using Florisil and MCX cartridges, respectively) with adequate overall recovery efficiency (71–96%). The statistical evaluation of the method reveals good linearity, accuracy, and precision for the compounds determined, with RSD values not exceeding 10.5%, while the limit of detection for all analytes was found to be 17 ng g−1. This method can be employed in phytoremediation studies of TER by Typha latifolia L. in constructed wetlands.

Effects of Swirl Velocities From Fan Assemblies Mounted on Lifting Surfaces

The penetration of a jet of fluid into a traversal moving stream is a basic configuration of a wide range of engineering applications, such as film cooling and V/STOL aircrafts. This investigation examines experimentally the effect of blowing ratio of fans in crossflow, and numerically, the effect of the swirl velocity of jets in crossflow, downstream of the injection hole. The experimental results indicated an agreement with typically straight jets in crossflow (no vorticity), illustrating that the trace of the jet, remains close to the wall and subsequently enhance cooling at low blowing ratios in the case of turbine blade applications. However, the rotation of the jet results in an imparity between the two parts of the counter rotating vortex pair and as a consequence, the injected fluid not only bends in the direction of the main stream but also diverts in the direction of the rotation in order to conserve its angular momentum. The induction of the swirl velocity on the injected jet destructs one of the two parts of the kidney vortex, which entrains fluid from the crossflow to the jet promoting the mixing between the two fluids while the trace of a swirled jet remains closer to the wall downstream of the injection hole. Finally, the use of contrarotating jet or fan configurations reduces the wall shear stress in a very great extent, leading to better thermal protection of turbine blades, as well as cancels out the yaw torques of each fan separately, resulting in better flight control of typical lift surface. [DOI: 10.1115/1.4002099]

Built-in current sensor with reduced voltage drop using thin-film transistors

A simple current. mirror using TFTs with input terminals which are capacitively coupled to the TFT gate, is used in this work, to design a built-in current sensor (BICS). The important feature in this application is that the voltage drop across the sensing TFT device can be reduced to almost zero value, while preserving transistor operation in the saturation region. This makes the proposed BICS appropriate for TFT applications without affecting the circuit operation. It also results in adequate linearity for the current monitoring, making the structure applicable to digital as well as to analog and mixed-signal circuit testing.

A built-in current sensor using thin-film transistors

A simple current mirror using TFTs with input terminals which are capacitively coupled to the TFT gate, is used in this work, to design a built-in current sensor (BICS). The important feature in this application is that the voltage drop across the sensing TFT device can be reduced to almost zero value, while preserving transistor operation in the saturation region. This makes the proposed BICS appropriate for TFT applications without affecting the circuit operation. It also results in adequate linearity for the current monitoring, making the structure applicable to digital as well as to analog and mixed-signal circuit testing.

Testing Parametric and Catastrophic Faults in Mixed-Signal Integrated Circuits Using Wavelets

In this paper a test method for testing both parametric and catastrophic faults in analog and mixed signal Integrated Circuits (ICs) is presented. It is based on the wavelet transformation of the measured signal, be it supply current (IPS) or output voltage (VOUT) waveform. The tolerance limit for the good or reference IC is set by statistical processing data obtained from a set of fault-free ICs. In the wavelet analysis, two test metrics one named discrimination factor and one utilizing Mahalanobis distances are introduced. Both metrics rely on wavelet energy computation. Results from the application of the proposed method in testing known analog and mixed signal IC benchmarks are presented showing the effectiveness of the proposed testing scheme.