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Biomedical subjects

G Papadopoulos

Publications and source records attributed to G Papadopoulos.

At least 55 records · Page 3Linked to original sources
PubMed1993

[Does the photoplethysmographic technique show an improvement in the measurement of the indirect blood pressure in intensive care patients?].

In the present report we investigated whether oscillometric and plethysmographic arterial blood pressure measurement techniques yielded different results compared to invasive blood pressure measurements in 18 mechanically ventilated and 14 spontaneously breathing patients. METHODS. Blood pressure was recorded simultaneously with plethysmographic, oscillometric, and invasive systems (FINAPRES 2300, HP 78352A, and 78534A, respectively). Invasive measurements were obtained in the radial artery. Short tubing was chosen in order to avoid transmission errors. The finger cuff of the FINAPRES 2300 was placed on the ipsilateral middle phalanx of the middle finger. The cuff of the oscillometric system was located on the contralateral arm. Differences in arterial blood pressure had been excluded. RESULTS. Histograms of the differences in the various pressure measurements, linear regression, and correlation coefficients were determined for quantitative comparison. The two non-invasive measurement devices (FINAPRES 2300, HP 78352A) yielded similar results in spontaneously breathing patients. In ventilated patients the reliability of oscillometric measurements was worse than that of the photoplethysmographic, especially for diastolic and mean arterial blood pressure values (Table 1, Figs. 2-4). DISCUSSION. The reasons for the differences between invasive and non-invasive measurement techniques are most likely due to problems with cuff handling for the plethysmographic device and the principles of oscillometric measurement. Both methods have to be optimised in hardware and software. However, the photoplethysmographic results showed an improvement in blood pressure measurement in ventilated patients. Due to the remaining deviations between the non-invasive and invasive measurements, especially in critically ill patients in the intensive care unit, direct measurement cannot be replaced by either of the non-invasive methods.

Adult↗
PubMed1993

[The reliability of the measurement of non-invasive oscillometric blood pressure instruments].

METHODS: The performance of five oscillometric blood pressure monitors was tested by means of a simulator. The oscillometric signals of two healthy patients were replayed. These signals were superimposed by sinusoidal artefacts with increasing amplitude, to examine the influence of artefacts on the accuracy of the measurement. Each measurement was repeated 15 times. RESULTS: The artefacts taken for this examination did affect the scattering of each single measurement rather than the mean value of the repeated measurements. The results did get worse with decreasing signal-to-artefact ratio. However, some monitors are able to handle these artefacts better than others. CONCLUSION: It is obvious that the implemented software for the artefact treatment and the determination of blood pressure values differs from manufacturer to manufacturer. Some devices were able to separate relevant signals from artefacts better than others. The most critical point of the oscillometric method is the correct determination of the maximum amplitude of the oscillations, because it directly influences the accuracy of the displayed blood pressure values. The availability of a simulator to test automated sphygmomanometers has shown to be a good tool to examine the performance of these devices.

Artifacts↗
PubMed1992

Extraoral retention of an obturator prosthesis.

In this study, a technique is described by which large obturators can be retained with an acrylic resin head plate. The technique entails attaching the prosthesis to an acrylic resin plate with a 2-mm-diameter wire and then attaching the plate to the patient's forehead with skin tape.

Aged↗
PubMed1992

Organisation of veterinary public health in the Western Mediterranean region.

This paper describes the administrative organisation of veterinary public health (VPH) activities in seven countries of the Western Mediterranean region. These structures vary greatly, as a function of the national administrations overall and, in particular, as a result of assigning VPH to either the Ministry of Agriculture or Public Health. Whereas the VPH unit is generally involved in specific veterinary food hygiene activities, the control of zoonotic diseases is most often assigned to the Veterinary Services. In most countries of the region, VPH is still approached as too narrow a discipline, and the importance of VPH activities is often not recognised by decision-makers at the highest governmental levels.

Albania↗
PubMed1990

Oxytocinergic innervation of the rat spinal cord. An electron microscopic study.

Pre- and postembedding immunocytochemical procedures were used, together with antisera raised against oxytocin or its neurophysin, to characterize oxytocinergic pathways in the rat spinal cord, at the electron microscopic level. Pre-embedding immunoperoxidase staining performed on vibratome sections revealed oxytocin- and neurophysin-positive axonal profiles and terminals scattered predominantly in laminae I and II of the dorsal horn and in the central gray (lamina X). They were also visible, but to a lesser extent, in the intermediolateral columns, at thoracic and lumbar levels. Postembedding immunogold staining performed directly on ultrathin sections of the same areas, fixed in osmium and embedded in resin, permitted to show clearly that the oxytocinergic axons made symmetrical and asymmetrical synaptic contacts onto dendritic profiles. It also allowed subcellular localization of the neuropeptide immunoreactivities which were restricted to relatively large, electron-dense vesicles in the immunopositive terminals. Oxytocinergic terminals were never seen to participate in glomerular configurations in the superficial layers of the dorsal horn nor were immunoreactive cell bodies visible in any spinal area. Our results provide direct morphological evidence that oxytocinergic pathways make synapses in several regions of the spinal cord, thus supporting the contention that oxytocin may exert neurotransmitter/neuromodulator actions in this area of the CNS.

Animals↗
PubMed1990

Solvent extraction of test plasmas for improved recovery of lupus anticoagulant activity.

Phospholipid procoagulant material mainly derived from platelets interferes or "bypasses" the more specific tests for lupus anticoagulants. Such material in test plasmas can be inactivated with recovery of lupus anticoagulant activity by simple extraction with chloroform. This solvent treatment damages mainly factors VIII, V, VII and IX. Ether and various other solvents were less damaging to these clotting factors but not quite as effective as chloroform in the recovery of lupus anticoagulant activity.

Autoantibodies↗
PubMed1990

Light- and dark-adapted bacteriorhodopsin, a time-resolved neutron diffraction study.

Recently, neutron diffraction experiments have revealed well-resolved and reversible changes in the protein conformation of bacteriorhodopsin (BR) between the light-adapted ground state and the M-intermediate of the proton pumping photocycle (Dencher, Dresselhaus, Zaccai and Büldt (1989) Proc. Natl. Acad. Sci. USA 86, 7876-7879). These changes are triggered by the light-induced isomerization of the chromophore retinal from the all-trans to the 13-cis configuration. Dark-adapted purple membranes contain a mixture of two pigment species with either the all-trans- or 13-cis-retinal isomer as chromophore. Employing a time-resolved neutron diffraction technique, no changes in protein conformation in the resolution regime of up to 7 A are observed during the transition between the two ground-state species 13-cis-BR and all-trans-BR. This is in line with the fact that the conversion of all-trans BR to 13-cis-BR involves an additional isomerization about the C15 = N Schiff's base bond, which in contrast to M formation minimizes retinal displacement and keeps the Schiff's base in the original protein environment. Furthermore, there is no indication for large-scale redistribution of water molecules in the purple membrane during light-dark adaptation.

Bacteriorhodopsins↗
PubMed1990

Water molecules and exchangeable hydrogen ions at the active centre of bacteriorhodopsin localized by neutron diffraction. Elements of the proton pathway?

Neutron diffraction is used to localize water molecules and/or exchangeable hydrogen ions in the purple membrane by H2O/2H2O exchange experiments at different values of relative humidity. At 100% relative humidity, differences in the hydration between protein and lipid areas are observed, accounting for an excess amount of about 100 molecules of water in the lipid domains per unit cell. A pronounced isotope effect was observed, reproducibly showing an increase in the lamellar spacing from 60 A in 2H2O to 68 A in H2O. At 15% relative humidity, the positions of exchangeable protons became visible. A dominant difference density peak corresponding to 11 +/- 2 exchangeable protons was detected in the central part of the projected structure of bacteriorhodopsin at the Schiff's base end of the chromophore. A difference density map obtained from data on purple membrane films at 15% relative humidity in 2H2O, and the same sample after complete drying in vacuum, revealed that about eight of these protons belong to four water molecules. This is direct evidence for tightly bound water molecules close to the chromophore binding site of bacteriorhodopsin, which could participate in the active steps of H+ translocation as well as in the proton pathway across this membrane protein.

Bacteriorhodopsins↗
PubMed1990

Dose to patients through nuclear medicine procedures in a department in northern Greece.

Diagnostic nuclear medicine procedures in a large hospital in northern Greece during 1984-1988 have been surveyed in order to estimate the radiation burden to the patients. The mean effective dose equivalent (EDE) was found to be 1.96 mSv/examination and 2.46 mSv/patient, allowing for the fact that a number of patients underwent more than one examination. Apart from EDE, absorbed dose has been calculated for bone marrow, thyroid, gonads, kidneys and bladder. Patients undergoing multiple examinations have been used to calculate true 'patient dose distribution' as well as 'patient time-weighted dose distribution'. Because of the predominance of renal examinations, 8.5 fatal renal malignancies are expected per 100,000 patients.

Greece↗
PubMed1990

Use of a simplified dilute Russell's viper venom time (DRVVT) confirms heterogeneity among 'lupus anticoagulants'.

A simplified dilute Russell's viper venom time (DRVVT) test--in which the venom, trace phospholipid and calcium were combined into a single reagent--was evaluated for the detection of lupus anticoagulants (LA) in 28 plasma samples containing non-specific circulating anticoagulants. In agreement with previous studies, the DRVVT was found to be insensitive to defects in contact and haemophilic factors and was only marginally affected by antibodies directed against factor VIII. Thus, the use of a DRVVT test in investigations of anticoagulants reduces the risk of confusing a haemorrhagic inhibitor of factor VIII with a non-haemorrhagic LA. In comparisons of sensitivity against activated partial thromboplastin time tests (APTT-Actin FSL and Organon-Teknika reagents) the simplified DRVVT was prolonged slightly more than the APTT in most of the test plasmas containing various non-specific circulating anticoagulants. Three anticoagulants affecting APTTs more than the DRVVT were found to be associated with anticardiolipin IgMs. APTT-prolonging anticoagulants, whether prolonging DRVVT tests or not, showed similar 'correction' of their APTTs by the addition of platelets or phospholipid. Thus, phospholipid-dependent or LA show heterogeneity. Those affecting only the APTT and not DRVVT should perhaps be classified differently.

Adult↗
PubMed1990

Intrahospital transport of critically ill patients.

Severe complications sometimes occur in critically ill patients during intrahospital transport. Possible causes may be inadequate ventilation, insufficient monitoring, interrupted application of vasoactive drugs, or disconnections and accidental extubation. We constructed a transport unit equipped with a respirator; capnometer; monitor to measure ECG, arterial and intracranial pressures, and temperature; and two syringe pumps that can be connected easily to the patient's bed. Gas is supplied by cylinders with oxygen and air. Electrical power is supplied by two accumulators connected to recharger and transformer devices that deliver 220 V (110 V). Since this transfer unit was introduced, we have had no unanticipated problems during intrahospital ICU patient transport.

Critical Care↗
PubMed1989

Effect of lasalocid sodium and molasses on performance of fattening lambs and on rumen liquor and blood parameters.

Two experiments were conducted to evaluate the effects of sugar beet molasses (0, 8 and 16%) with or without lasalocid sodium (33 ppm) on rumen liquor and blood parameters of sheep, and on fattening reared Karagouniko breed lambs. In Expt. 1 six adult Karagouniko fistulated wethers were fed six different pelleted diets. The results showed that lasalocid decreased (P less than 0.01) total VFAs concentration in the rumen (7.1%) by reducing (P less than 0.001) acetic, n-butyric and iso-valeric acids while increased (P less than 0.001) propionic acid concentrations. The same trends were observed in molar proportions of the individual VFAs. The total VFAs production was also depressed by 13.75% when molasses were used at the level of 16%. No interaction among the main treatments was observed with the exception of L X M with 16% molasses where the propionic acid concentration decreased, and those of butyric and iso-valeric acids increased. Lasalocid did not alter the mean values of rumen liquor pH and ammonia nitrogen concentration while molasses increased the later parameter. No significant differences on dietary protein degradability were observed among treatments. Lasalocid reduced the beta-HBA concentration by 13% in the blood while molasses increased it (P less than 0.001). Free fatty acids' concentration was decreased by the molasses inclusion to the diets, while lasalocid didn't alter blood glucose concentration. Finally, the number of protozoa in the rumen liquor was reduced by 49 and 70% at 0 and 5 hours post feeding respectively with the addition of lasalocid to the diets, regardless of the use of molasses. In Expt. 2 utilized 86 weaned male Karagouniko fattening lambs, with initial mean LW 13 kg, for 60 days. They were assigned to six groups and fed ad libitum with diets of the same composition as in Exp 1. Lasalocid increased the growth rate by 8.6%, reduced feed consumption by 4.8% (P less than 0.005) and improved feed conversion by 11.8%. Molasses also improved growth rate by 16-34% and increased feed consumption by 15-22%. The interaction of L X M to feed consumption was significant (P less than 0.001). None of the treatments had an effect on carcass characteristics. Finally lasalocid showed its positive action when it was used in combination with molasses in ruminants' diets.

3-Hydroxybutyric Acid↗
PubMed1989

The frequency of chromosome anomalies in human preimplantation embryos after in-vitro fertilization.

Previous studies have reported chromosome aberrations in human pre-embryos after in-vitro fertilization (IVF). Although the reason for these abnormalities is not clear, there is evidence that they can arise during gametogenesis, fertilization or cleavage. The present study has examined further the incidence of chromosome abnormalities in human pre-embryos after IVF, using oocytes recovered from normal volunteer women and from women undergoing infertility treatment in an embryo-replacement programme. Chromosome preparations were performed for 75 pre-embryos. Of these 35 (47%) gave at least one metaphase in which analysis was possible. The overall incidence of abnormal pre-embryos was 40% (14/35). The absolute frequency of aberrations was 9% for trisomies, 3% for polyploidies, 26% for structural anomalies and 3% for hypodiploidies. Five pre-embryos were found to be mosaics, three of which had each one trisomic metaphase. In five of the pre-embryos multiple anomalies were found. In 13 of the 14 abnormal pre-embryos the aberrations were found in only one metaphase. The present study demonstrates that trisomic mosaicism may not be a rare event in human pre-embryos. Further evidence is provided that mitotic non-disjunction is important for the production of aberrations in human pre-embryos.

Blastocyst↗
PubMed1989

The frequency of chromosome anomalies in human unfertilized oocytes and uncleaved zygotes after insemination in vitro.

Data on first trimester human abortions have shown chromosome aberrations in approximately 50% of the cases, most of which were trisomies. More than 80% of these trisomies have been attributed to an error in the oocyte. In this study we investigated the frequency of chromosome anomalies in 44 human unfertilized oocytes and 13 uncleaved zygotes after insemination in vitro. The oocytes were aspirated from preovulatory follicles in parous volunteer donors and patients participating in an embryo replacement programme. Thirty cases could be analysed, 18 of which (60%) carried a chromosome abnormality. There were two hyperhaploidies (6.7%), four hypohaploidies (13.3%), three polyploidies (10%), six with structural aberrations (20%) and five diploidies (16.7%). The incidence of these abnormalities, except for the structural anomalies, was similar to that reported previously. The higher frequency of structural aberrations in the present study may be related to delayed cytogenetic analysis for up to 48 h after insemination.

Abortion, Spontaneous↗
PubMed1989

Valvuloplasty with large trefoil balloons for the treatment of congenital pulmonary stenosis.

Percutaneous balloon valvuloplasty was performed in 16 children, 1 1/2 to 14 years old, with congenital pulmonary stenosis with teh use or trefoil balloons. These balloons, which consist of 3 identical angioplasty balloons, do not interrupt completely the blood flow during inflation. The size of the trefoil balloons used was 30 to 50% larger than the valve anulus. A obtain an effective pulmonary valvuloplasty in two patients with large valve anulus. The mean prevalvuloplasty systolic gradient fo 78.2 +/- 28.9 mmHg (range 40 to 140 mmHg) was reduced to 20.3 +/- 5.7 (range 10 to 30 mmHg) after valvuloplasty. No patient developed significant hypotension or bradycardia or other complications as a result of the procedure. The findings demonstrate that percutaneous balloon valvuloplasty with oversized trefoil balloons effectively treated congenital pulmonary stenosis without complications in the cases studied. The use of large trefoil instead of single balloons of a similar diameter is advantageous since they cause no significant compromise of the cardiac output during valvuloplasty.

Adolescent↗