PubMed Health⌕ Search

Biomedical subjects

G Papadopoulos

Publications and source records attributed to G Papadopoulos.

At least 37 records · Page 2Linked to original sources
PubMed2000

Compound heterozygous hemochromatosis genotype predicts increased iron and erythrocyte indices in women.

BACKGROUND: Women who inherit heterozygosity for the C282Y mutation of the HFE gene may have increased serum iron indices and hemoglobin and are less likely to develop iron deficiency compared with women with the wild-type genotype. METHODS: We performed a cross-sectional analysis of 497 women 20-44 years of age and 830 women >51 years of age drawn from the Busselton (Australia) population study to assess the effects of the HFE genotype on serum iron and hematology indices. RESULTS: Heterozygosity for the C282Y mutation occurred in 13.8% of the study population, comprising 11.8% C282Y wild-type heterozygotes and 2.0% C282Y/H63D compound heterozygotes. In the younger age group, C282Y wild-type women did not have significantly increased serum iron, transferrin saturation, or hemoglobin values, and were not protected from developing iron deficiency, compared with women of the same age with the wild-type genotype. Young compound heterozygous women had higher means for serum iron (25.0 vs 16.9 micromol/L; P <0.001), transferrin saturation (42.0% vs 25.6%; P <0. 05), hemoglobin (139.4 vs 132.3 g/L; P <0.05), and corpuscular volume (91.1 vs 87.7 fL; P <0.05), and a higher median ferritin (53 vs 44 microg/L; P <0.05) compared with the wild-type genotype. Similar results were observed for compound heterozygotes in the >51 years age group. CONCLUSIONS: Women with the compound heterozygous HFE genotype C282Y/H63D, but not the C282Y wild-type genotype, had increased values for serum iron and transferrin saturation, and the younger age group also had increased hemoglobin values. We conclude that the compound heterozygous genotype may have a beneficial effect in protecting women from iron deficiency.

Adult↗
PubMed1999

Assessment of the performances of three oscillometric blood pressure monitors for neonates using a simulator.

BACKGROUND: The majority of monitors for non-invasive measurement of blood pressure in neonates and infants use the oscillometric method. OBJECTIVE: To use a simulator to investigate the overall system accuracy for three oscillometric blood pressure monitors. The tested devices are DINAMAP 8100 (Critikon), SpaceLabs M90426 (SpaceLabs Medical)and the module HP M 1008B (Hewlett-Packard). METHODS: The blood pressure values obtained by the three devices were compared with those of the invasive reference. A blood pressure simulator was used for testing the performance of the three blood pressure monitors. RESULTS: The Dinamap and SpaceLabs readings are generally in good agreement with the invasive reference. In contrast, the HP M 1008B readings for the diastolic and mean arterial pressures are inaccurate (the mean errors are 21 and 15mmHg, respectively). CONCLUSION: These results contradict our previously published data obtained when a different simulator (Cufflink)was used. These findings are important, because blood pressure values that are too low can result in a different therapeutic approach being applied, for newborn babies have only a small range of mean arterial pressure for the autoregulation of the cerebral blood flow.

Blood Pressure↗
PubMed1998

Selective deamidation by tissue transglutaminase strongly enhances gliadin-specific T cell reactivity.

Celiac disease (CD) is caused by gluten ingestion in susceptible individuals. Tissue transglutaminase (tTG)-specific Abs are characteristic of CD, and increased tTG activity has been observed in the jejunal biopsies of patients. Here we demonstrate that tTG selectively deamidates gluten peptides, which results in strongly enhanced T cell-stimulatory activity. To our knowledge, this is the first example of an enzymatic modification of a food protein that affects T cell recognition. Moreover, these modifications may lead to the amplification of gluten-specific T cell responses in the gut and consequently may be important for the development of CD.

Amides↗
PubMed1998

Huge non-functioning pancreatic cystic neuroendocrine tumour: a case report.

A case of an 18-cm large cystic, non-functioning endocrine (islet cell) tumour located at the tail of the pancreas in a 29-year-old Caucasian female is reported here. Pre-operative radioimmunoassays for pancreatic peptides were negative, while immunohistochemistry confirmed the neuroendocrine nature of the tumour. This is the largest cystic non-functioning islet-cell tumour so far described.

Adenoma, Islet Cell↗
PubMed1997

Distinct central anticholinergic syndrome following general anaesthesia.

The purpose of this prospective study was to identify the incidence of a distinct central anticholinergic syndrome following routine anaesthesia. For 2 months, all inpatients aged more than 15 years scheduled for elective procedures and cared for in the recovery room were investigated for symptoms of the syndrome. Patients with neuropsychiatric disease or other disorders that could alter consciousness were excluded. Prolonged action of anaesthetics or relaxants, respiratory depression and metabolic disorder were ruled out before making the diagnosis. Out of 962 patients (366 men, 596 women), 18 (4 men, 14 women) developed the syndrome. The difference between men and women was not statistically significant. Six out of 60 women developed the syndrome after a hysterectomy with or without adnectomy/oophorectomy, and this high incidence was significantly different from that observed after all other procedures in women (P = 0.003) or all other gynaecological procedures (P = 0.013). The reason for this is unknown. In six of the 18 cases, untreated prolonged somnolence lasted for more than 2 h. All patients woke up after an injection of physostigmine, but six of them relapsed into somnolence and needed a second, and in one case a third, injection. The findings of the study emphasize that, when there is delayed recovery from anaesthesia, the diagnosis of central anticholinergic syndrome should be considered if other accessible causes for that condition have been excluded.

Adolescent↗
PubMed1996

[Intraoperative contrast echocardiography for detection of a patient foramen ovale using a provocation test and ventilation with PEEP respiration].

UNLABELLED: Intraoperative paradoxical air embolism may occur even if a patent foramen ovale (PFO) is excluded by contrast transoesophageal echocardiography (TEE) under 20 cm H2O positive airway pressure. It is questionable whether the combination of PEEP and ventilation with a large tidal volume increases the sensitivity of contrast TEE in detecting a PFO. METHODS: Eighty healthy patients (ASA status I, II) scheduled for surgery in the supine position and ranging from 25 to 72 years of age were investigated by TEE, which was performed in the biatrial viewing mode (short axis). Echocardiographic contrast (10 ml agitated gelatine solution) was injected during two different ventilation manoeuvres. Manoeuvre I: Contrast injection during the application of 20 cm H2O positive airway pressure for 5 s. The pressure was released when the right atrium became completely opacified by echo targets. The injected bolus was observed throughout the ventilatory cycle, with special attention being given to early expiration and systole. A right-to-left shunt was assumed if five echo targets were observed in the left atrium. Manoeuvre II: Contrast injection during ventilation with PEEP (15 cm H2O), a tidal volume of 1,200 ml, and a respiratory rate of 6/min. RESULTS: The frequency of a PFO causing a right-to-left interatrial shunt was 8.7% (7 cases) in manoeuvre I and 15% (12 cases) in manoeuvre II. In one case a PFO was diagnosed intraoperatively by chance. DISCUSSION: The use of provocation manoeuvres including ventilation with PEEP and high tidal volumes might improve the ability to detect a PFO presenting with right-to-left interatrial shunt by intraoperative contrast TEE, but does not have 100% sensitivity. However, our results clearly indicate that ventilation with PEEP and high tidal volumes may predispose to paradoxical embolism.

Adult↗
PubMed1996

[Evaluation of the oscillometric blood pressure monitors: Dinamap 1846 and HP M-1008B].

Using the PTB simulator, which emits real signals from patients, we examined the precision of the oscillometric blood pressure measurement with the Dinamap 1846 (Critikon) and the HP M-1008B (Hewlett Packard). For this purpose we simultaneously registered invasive arterial pulsewave, cuff pressure and cuff pressure oscillations of 20 patients from our intensive care unit and stored them in the database of the simulator. The invasive reference blood pressure values were determined following the recommendations given by the Association for the Advancement of Medical Instrumentation. The invasive system showed a cut-off frequency of 35 Hz; the damping constant was 0.21. With 49 record signals from patients we carried out 15 simulated measurements each. From a total of 49 bio-signals from patients the Dinamap 1846 was able to process 41 signals and the HP M-1008B 47 signals. The mean error of the oscillometric blood pressure measurement of the systolic, diastolic and mean arterial pressure amounted to -2.50 mmHg, 3.35 mmHg (P < 0.05) and 1.51 mmHg with the Dinamap 1846 and to -8.5 mmHg (P < 0.001), -5.15 mmHg (P < 0.001) and -5.58 mmHg (P < 0.001) for the HP M-1008B. The 95% confidence limit for the systolic, diastolic and the mean arterial pressure amounts to 56 mmHg, 30 mmHg and 35 mmHg for the Dinamap 1846 and 50 mmHg, 38 mmHg and 35 mmHg for the HP M-1008B. The differences between that two instruments could be caused by the different algorithms for the calculation of blood pressure values and different artefact detection and elimination techniques. The results of the performance tests we achieved with the PTB simulator correspond to the results of other clinical examinations. The American Association for the Advancement of Medical Instrumentation recommends a maximum mean error of 5 +/- 8 mmHg. None of the examined instruments lay within these limits. Due to the systematic and stochastic errors, we think that the Dinamap 1846 (Critikon) and the HP M-1008B (Hewlett Packard) do not achieve performance levels that are adequate for measuring critically ill patients.

Adult↗
PubMed1996

Surgical treatment of the divided flexor digitorum profundus tendon in zone 2, delayed more than 6 weeks, by tendon grafting in 50 cases.

The surgical treatment of the divided FDP tendon, more than 6 weeks old, in zone 2 is reviewed in 50 patients. The method used was the excision of the divided FDP tendon and the insertion of a thin tendon graft. There were 50 patients in this study; 36 were male and 14 female, aged from 18 to 60 years. All patients were markedly disabled because of loss of strength of the involved finger. Follow-up ranged from 1 to 25 years following tendon grafting. In 35 patients plantaris tendon was used and in 15 patients palmaris longus. Definite advantages were found in using the tendon grafting procedure; strength, dexterity, pinch and grasp were markedly improved. Functional results were evaluated by the Boyes method, with the Pulvertaft method as a secondary assessment. Among the 50 patients, 80% had excellent and good results (excellent 32%, good 48%) and 20% fair.

Adult↗
PubMed1996

Frequency of HLA antigens in Graves' hyperthyroidism and mitral valve prolapse.

BACKGROUND AND AIMS OF THE STUDY: An association between Graves' hyperthyroidism (G) and mitral valve prolapse (MVP) has been reported, but possible genetic linkage between the two disorders has not. METHODS: One hundred and five patients (pts) with G were studied after therapy, in a euthyroid state. MVP (auscultatory plus echocardiographic findings) was present in 33 pts (31%). Frequency of human lymphocyte antigens (HLA) in pts with G and in pts with G plus MVP was compared to 170 normal subjects (NL). There was no difference in HLA-A antigens among the three groups. RESULTS: The frequency of HLA B-15 was greater in pts with G plus MVP (18.9%) compared to NL (3%) and to G without MVP (4.2), p < 0.01. The frequency of HLA-B39 was greater in G without MVP (13.8%) compared to NL (4.1%), p < 0.01. The HLA DRB1*1601-2 was more frequent in G with (30.3%) or without (29.2%) MVP compared to NL (13.5%), p < 0.01. The frequency of HLA DRB1*1401-10 and DQA1*0104 were greater in NL (16.5%) compared to G with (3.0%) or without (4.2%) MVP, p < 0.01. CONCLUSIONS: The data confirmed previous observations that the frequency of MVP is high in pts with G. Further, the data indicated a possible genetic linkage between the two abnormalities.

Adolescent↗
PubMed1995

[Loss of brain stem auditory evoked potential waves I and II during controlled hypotension].

For surgical removal of a malignant choroid melanoma, it is necessary to reduce systolic blood pressure to around 50-60 mmHg in order to prevent choroidal haemorrhages. However, blood pressure reduction is associated with the risk of cerebral ischaemia. We report a patient with a malignant choroid melanoma in whom waves I and II of the brainstem auditory evoked potentials (BAEP) disappeared during surgery under controlled arterial hypotension and hypothermia (31.1 degrees C). The waves could be recorded again immediately after the mean arterial pressure was increased from 48 to 77 mmHg. The oesophageal temperature had dropped by 0.3 degrees C at this time. The 2-channel electroencephalogram (EEG) showed no irregularities during this time period. A bilateral, reversible, apparently blood-pressure-dependent loss of waves I and II during arterial hypotension despite a normal EEG has to our knowledge not been previously described in the literature. The isolated loss of waves I and II with maintenance of waves III, IV, and V is unusual. The literature contains reports of acoustic neurinoma patients in whom only wave V could be recorded. This is regarded as an indication of continued impulse conduction despite the loss of waves I to IV. Others have observed a patient with temporary and reversible loss of BAEP wave I due to vasospasm of the internal auditory artery that apparently occurred during or shortly after manipulation of the internal auditory meatus. Assuming anatomic peculiarities in the blood supply to the generators of the BAEP waves, a stenosis of the basilar artery could be considered as the cause of the bilateral reversible loss of waves I and II. Another potential source could be induced hypothermia, but this does not seem very likely because the patient's temperature was 0.3 degrees C lower at the return of the waves than at their loss.

Choroid Neoplasms↗
PubMed1994

Venous and paradoxical air embolism in the sitting position. A prospective study with transoesophageal echocardiography.

This prospective study investigates the frequency of patent foramen ovale (PFO), venous air embolism (VAE) and paradoxical air embolism (PAE) by transoesophageal echocardiography (TOE) in neurosurgical patients operated on in the sitting position. The risk of PAE after exclusion of PFO is assessed. A PFO was identified by pre-operative TOE and VAE and PAE by continuous intraoperative TOE. Sixty-two patients were divided into two groups, 22 patients were studied in group 1 (posterior fossa surgery) and group 2 (cervical surgery) contained 40 patients. Pre-operative TOE demonstrated a PFO in 5 of the 22 patients in group 1 (23%). Patients with proven PFO were excluded from the sitting position. Two further patients of this group (12% of 17 patients), in whom a PFO had been excluded pre-operatively, nevertheless had PAE, air occurring in all cavities of the heart. In group 2 the incidence of PFO was 4 out of 40 patients (10%). No PAE was observed in this group. Three morphological types of VAE with different haemodynamic and ventilation changes were demonstrated. VAE was observed in 76% of all posterior fossa operations and in 25% of cervical laminectomies. We conclude that a pre-operative search for PFO is mandatory considering its incidence of 23% in group 1 and of 10% in group 2, and the risk of PAE. If a PFO is detected, the sitting position should be avoided. A residual risk for PAE remains despite exclusion of PFO because the reliability of TOE is limited. TOE is the method of choice for detecting VAE and PAE.

Adult↗
PubMed1994

[Arterial blood pressure measurement with oscillometric instruments in newborns and infants].

Non-invasive blood pressure measurements by the auscultatory method do not provide reliable, reproducible blood pressure values in many neonates because the Korottkoff sounds are often very difficult to detect. This resulted in the development of many alternative indirect methods. Devices utilizing the Doppler ultrasound technique have not found wide acceptance. Since the introduction of automated oscillometric blood pressure monitors, arterial blood pressure has been increasingly brought into discussion as an indicator of the circulatory state. This is the first study to investigate the similarity and reproducibility of the data obtained with five oscillometric devices for measurement of blood pressure in neonates. MATERIALS AND METHODS. Since investigations on the technical performance are not practical in the clinical setting of a neonatal or pediatric ward, we used two simulators, the CuffLink (Dynatech, Nevada, USA) and a device developed by the PTB (Physikalisch-Technische Bundesanstalt). While the latter uses oscillations originally obtained from neonates, the CuffLink uses artificial and therefore ideal signals for the blood pressure monitors. The signals used for the PTB simulator were obtained from three neonates with an average age of 2 months and a weight of 3.5 kg, 4.4 kg, and 7.8 kg. The following blood pressure monitors were studied: Hoyer/Colin, BP-1001; Datex, Cardiocap II; SpaceLabs, model no. 90426; Hewlett-Packard, NBP M1008A; Critikon, Dinamap 1846. Before the measurements were started, the cuff pressure display of each monitor was checked according to a verification procedure. Although the 4 mmHg margin of error was not exceeded, the results were corrected. RESULTS. The results of the measurements show significant differences between the blood pressure monitors from the various manufacturers, with the differences for the ideal signals of the CuffLink-Simulator being less pronounced than those for the PTB simulator. Direct comparison of results is therefore often impossible. The standard deviation, taken from 20 measurements per monitor and simulation, is below 4 mmHg for both simulators. We can therefore conclude that the reproducibility of data is satisfactory and the emerging trend is reliable. DISCUSSION. The difference between the results of the PTB simulator and the CuffLink are probably due to the method of evaluation and the identification of artifacts of each blood pressure monitor. This is also confirmed by the studies of Mieke et al. The manufacturers should provide devices that display comparative results and improve the algorithms for detection of artefacts, increasing the accuracy of their blood pressure monitors. This could be done with the help of simulators. Considering the pathophysiological characteristics of neonates and infants, the systematic differences between the five monitors have to be regarded as serious.

Blood Pressure Monitors↗
PubMed1994

[Intraoperative transesophageal versus preoperative transthoracic contrast echocardiography. A method for detection of patent foramen ovale in neurosurgical patients].

Preoperative detection of a patent foramen ovale (PFO) may be achieved employing either transthoracic echocardiography (TTE) with the Valsalva manoeuvre in the awake patient or trans-oesophageal echocardiography (TEE) in the anaesthesised patient. Our study was undertaken to validate these methods with regard to their efficacy in identifying patients at risk for paradoxical air embolism (PAE). METHODS. In 67 patients ranging from 28 to 70 years of age, TTE was performed utilising the Valsalva manoeuvre prior to surgery. The patients were informed about all procedures and agreed to take part in the study. After induction of anaesthesia the patients were evaluated with TEE in the supine and sitting positions. At end-inspiration 10 ml agitated gelatine solution (Gelafundin) was injected through a central venous catheter into the right atrium after airway pressure of 20 cm H2O had been maintained for 5 s. The injected bolus was observed throughout the ventilatory cycle, with special attention being given to early expiration and systole. A right-to-left shunt was assumed if five echo targets were observed in the left atrium. RESULTS. The prevalence of PFO detected by TTE/Valsalva was 9%. The diagnosis was confirmed by TEE in 2 patients in the supine and 1 in the sitting position. An echocardiogram in these patients showed bulging of the septum to the left, which was not seen in those patients in whom PFO was detected only by TTE. DISCUSSION. The reason for the lower incidence of PFO detected by TEE during airway pressure 20 cm H2O may have been an insufficient increase of pressure in the right atrium with a negative right-to-left atrial pressure gradient. A standardised ventilation manoeuvre with supra-atmospheric airway pressure of 20 cm H2O is not sufficient. Bulging of the intra-atrial septum from right to left during airway pressure is a possible indication of the efficacy of the manoeuvre, regardless of the influence of the breathing pattern.

Adult↗
PubMed1993

The emergence of the cortical GABAergic neuron: with particular reference to some peptidergic subpopulations.

The technical developments which have led to our present ability to make predictions about neurochemical identity from morphological observations are retraced with particular reference to the GABAergic neuron and its many subdivisions. The synaptology of four peptidergic sub-populations in the cerebral cortex is examined and described in detail. It is concluded that the recognition of Gray Type 1 and Type 2 synapse types continues to provide a key element in our analysis and understanding of the connectivity of the CNS.

Animals↗
PubMed1993

[The action of atracurium and vecuronium in chronically hemodialyzed patients].

UNLABELLED: Reports on the duration of action of atracurium (Atr) and vecuronium (Vec) in patients with renal failure are contradictory. It is either stated that the duration is equal for both relaxants or that Atr acts for a longer duration. Because of these conflicting results, we measured the times for latency (tL), onset (tA), duration of action (tW), and recovery (tE) for both agents. METHODS: Fourty patients with end-stage renal failure on chronic haemodialysis were randomly assigned to receive either Atr (0.4 mg.kg-1 BW) or Vec (0.08 mg.kg-1 BW). After induction with thiopentone and 0.1 mg fentanyl, anaesthesia was maintained with nitrous oxide and 1 vol.% ethrane and expiratory CO2 partial pressure was kept between 4.6 and 4.9 kPa. If the twitch height of T1 regained 25% of the pre-relaxation value, 20% of the initial relaxant bolus was injected. Relaxation was monitored with a relaxograph after calibration of the device. After testing for a normal distribution, statistical analysis was done by Student's t-test. A value of P < or = 0.05 was chosen for statistical significance. RESULTS: There were no significant differences regarding tL (Atr: 1.0 +/- 0.5 min; Vec: 1.1 +/- 0.5 min) and tA (Atr: 5.5 +/- 2.1 min; Vec 4.1 +/- 2.4 min); tW (Atr: 21.3 +/- 13.1 min; Vec 31.7 +/- 15.6 min) and tE (Atr: 19.0 +/- 9.0 min; Vec 30.1 +/- 19.0) were significantly different. DISCUSSION: Our results are not in accordance with those authors who found in comparison with Atr an equal or shorter duration of action for Vec in patients with renal failure. If the duration of action is equal in subjects with no renal insufficiency, our measurements are in accordance with kinetic evaluations showing the same clearance and half-life for Atr in patients with and without renal insufficiency, but 40% diminished clearance and 60% prolonged half-life for Vec in renal insufficiency.

Adult↗
PubMed1993

[Postoperative air embolism caused by pneumatocephalus following occlusion of the posterior fossa. A rare complication indicative of a bridging vein disruption].

Many neurosurgeons prefer the sitting position for patients undergoing surgery in the posterior fossa because of the easier access and better conditions for haemostasis. Pneumatocephalus is a possible consequence of surgery in the posterior fossa with the patient in the sitting position. When this occurs air may enter the subarachnoid space, the cisternae, the ventricular system or the subdural space; it becomes more likely when any of the following is/are present: loss of CSF, a large cavity resulting from surgery, external or internal drainage of CSF, osmotic diuresis, and hyperventilation. Distances of 1-2 cm between cranium and brain may be found. The rupture of bridging veins may cause a subsequent subdural haematoma. Air embolism due to pneumatocephalus via the same vein after closure of the cranium is in this paper for the first time. Case report. A 37-year-old man with known Hippel-Lindau disease presented for posterior fossa surgery for treatment of a haemangioblastoma of the right cerebellar hemisphere. Surgery was done with the patient in a sitting position. Apart from one short episode of air embolism without haemodynamic changes no intraoperative complications occurred. After closure of the cranium and galea an unexpected and inexplicable air embolism of 10 min duration occurred again. TEE demonstrated the air looking like a string of beads in the right atrium. As complete skin had already been closure no explanation for the air embolism could be found. The patient was positioned supine, and air was no longer detectable in the right heart after 1 min. Approximately 1 h later both pupils were dilated and unreactive to light.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Chloral hydrate for pediatric ophthalmologic examinations.

Although chloral hydrate sedation has been recommended as an alternative to general anesthesia for pediatric examinations, we have had inconsistent effects after rectal applications for ophthalmologic examinations. A retrospective analysis of rectal chloral hydrate for computer-assisted tomographic (CT) examinations on 20 pediatric patients revealed that after a single application, sedation was sufficient in only 4 cases. In 14 cases, additional doses and/or drugs were required. Altogether, 6 examinations were canceled because of insufficient sedation. Therefore, the safety and effectiveness of oral chloral hydrate (60-100 mg/kg) was studied prospectively in 32 pediatric ophthalmologic examinations of 20 patients. The unpalatable taste of chloral hydrate may result in inconsistent intake, but all intended examinations and manipulations could be carried out with only minimal side effects. Oral chloral hydrate seems to be safe and effective for painless pediatric examinations and may be more reliable than rectal chloral hydrate.

Anesthesia, General↗