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Biomedical subjects

C Papageorgiou

Publications and source records attributed to C Papageorgiou.

At least 55 records · Page 3Linked to original sources
PubMed1998

Evaluation of first-trimester screening by fetal nuchal translucency and maternal age.

The aim of this screening study was to evaluate first-trimester screening for chromosomal defects by fetal nuchal translucency thickness at 10-14 weeks of gestation in four Fetal Medicine Units in Greece. Estimates of the risk for trisomy 21 were calculated taking into account fetal nuchal translucency thickness and maternal age. There were 3550 cases; the median maternal age was 29 years (range 16-48 years); and 277 (7.8 per cent) were over 37 years. The median crown rump length was 60 mm (range 38-85 mm) and the fetal nuchal translucency thickness increased with crown rump length and measurements were above the 95th centile in 101 (2.9 per cent) of the cases. The adjusted risk was 1 in 300 or more in 172 (4.9 per cent) of the cases and the high-risk group contained ten of the 11 (91 per cent) fetuses with trisomy 21 and all 11 fetuses with other chromosomal defects. The findings of this study provide further evidence for the high efficacy of screening for chromosomal abnormalities by fetal nuchal translucency and maternal age.

Adolescent↗
PubMed1998

Correlation between denervation activity and compound muscle action potential amplitude in hereditary motor and sensory neuropathy I and II.

Studying the electrophysiological characteristics of the various types of Charcot-Marie-Tooth disease is important in the understanding of its pathophysiology. The purpose of this study was to identify the frequency of fibrillation potentials and positive sharp waves (FP/PWs) in HMSN I and II and, since they are indices of denervation, to elucidate whether they are correlated with the amplitude of compound muscle action potentials (CMAP). We reviewed the electrophysiological findings of 47 patients who have been studied in our hospital and found to suffer from Charcot-Marie-Tooth polyneuropathy. FP/PW were graded according to a 4-grade scale and the 38 m/sec criterion for motor conduction velocity (MCV) was used for distinction between HMSN I and II subgroups. Seventy percent of HMSN II patients and 81% of HMSN I patients showed fibrillation potentials in the upper or lower limbs. There was no difference in the frequency of FP/PW appearance between the two groups. In the HMSN II group the FP/PW grade correlated with CMAP amplitude in the upper limbs. In both groups there was no correlation between FP/PW grade and MCV. Our findings might indicate that in HMSN I there is a considerable axonal destruction that occurs concurrently with myelin loss.

Action Potentials↗
PubMed1997

Essential trace element alterations in amyotrophic lateral sclerosis.

Although trace elements have been implicated in the pathogenesis of amyotrophic lateral sclerosis (ALS) for a long time, new evidence has connected familial ALS with the metalloenzyme copper-zinc superoxide dismutase, thus reinforcing the study of their metabolism. This work presents the results of serum and cerebrospinal fluid levels of copper, zinc, manganese and magnesium, by atomic absorption spectrophotometry. Statistically significant decreased cerebrospinal fluid and serum copper levels were found in patients compared to the control group (20.25 +/- 7.09 vs. 30.86 +/- 16.02 SD micrograms/l and 913.21 +/- 165.55 vs. 1020.17 +/- 197.76 SD micrograms/l) while serum manganese levels were found to be increased in patients (3.59 +/- 0.89 SD micrograms/l) compared to controls (3.03 +/- 1.23 SD micrograms/l). Zinc and magnesium levels were unchanged. Our findings indicate an essential trace element imbalance in the disease.

Adult↗
PubMed1997

Changes of presaccadic cortical activity when performing horizontal, visually guided saccades.

When a visually guided saccade task is running, the presaccadic potential obtained in the initial period of the task differs from those obtained later, while the subject's oculomotor performance remains unaffected. These time-related changes of cortical activity consist both of an overall decreasing electrical activity as well as a selective one over certain cortical areas. The generalised reduced activity already described in earlier studies is considered as an unspecified effect such as fatigue or decreased motivation. On the contrary, the pronounced selective changes of cortical activity obtained over cortical areas such as the centro-parietal and frontal cortices, should be related with more specific, that is, visuomotor function. We assume that at the beginning of the task of the performance of the saccade needs the activation of several cortical areas but later on the same oculomotor plan runs sufficiently under subcortical control.

Adult↗
PubMed1997

Conformational control of cyclosporin through substitution of the N-5 position. A new class of cyclosporin antagonists.

Cyclosporin A (CsA) can be regiospecifically alkylated at the NH of Val-5 with reactive bromides in the presence of phosphazene-base P4-t-Bu to yield derivatives 2-5. These are devoid of immunosuppressive activity in vitro but they have binding affinity for cyclophilin A (CypA) similar to that of CsA and thus represent a new class of cyclosporin antagonists. 1H NMR (DMSO-d6) studies have shown that the compounds exist in a single, all trans conformation. A comparison of this NMR data with X-ray crystallographic analysis of a CypA/CsA derivative complex demonstrates that the solution structure does not correspond to the bioactive conformation.

Cyclosporine↗
PubMed1997

Ascorbate in healthy subjects, amyotrophic lateral sclerosis and Alzheimer's disease.

The aim of the present study was to report the levels of ascorbic acid in amyotrophic lateral sclerosis (ALS) and Alzheimer's disease (AD) and the effectiveness of ascorbic acid homeostasis in the central nervous system. Plasma and CSF ascorbic acid levels were measured by high performance liquid chromatography in 19 ALS patients, 17 AD patients and 15 controls. No statistically significant difference was found between patients and controls. However, wide fluctuations of plasma concentrations were found to result in relatively stable CSF levels, by appropriate adjustments of CSF/plasma ratio. It appears that in normal subjects and in the disease under study, this ratio reflects the activity of the choroid plexus ascorbate transporter.

Alzheimer Disease↗
PubMed1997

Cognitive function in non-demented individuals complaining of short-term memory disturbances: a study with event-related potentials (P 300) and brain CT scan.

Event-related potentials (ERPs) were elicited in 30, non-consecutive, non-demented individuals, complaining of short-term memory disturbances. Fifteen of them had a moderate diffuse cerebral atrophy on their brain CT and the other 15 had a negative brain CT. ERPs were also elicited in 15 age-matched controls with no reported memory disturbances and negative brain CTs. The statistical analysis showed that the group of individuals with cerebral atrophy had a significantly prolonged P300 (P3) latency and a decreased P3 amplitude compared to controls. It is concluded that among persons complaining of short-term memory disturbances, the individuals who show cerebral atrophy, taken as a group, have a P3 latency prolongation and/or low P3 amplitude a finding which reflects an impaired information processing.

Adult↗
PubMed1996

Prenatal diagnosis of X-linked spinal and bulbar muscular atrophy in a Greek family.

X-linked spinal and bulbar muscular atrophy (SBMA) is a late-onset motor neuron disorder which is caused by an expansion of the trinucleotide repeat (CAG)n in the first exon of the androgen receptor gene. Two cases of prenatal testing for the disease in a Greek family are reported. An affected male died in his late 50s of this disorder and his 30-year-old daughter (an obligate carrier) asked for prenatal testing for SBMA. DNA analysis revealed that she indeed carried an expanded allele of 40 repeats, as well as a normal size allele of 24 repeats. Prenatal diagnosis of SBMA was performed when, on two successive pregnancies, two male fetuses with the expanded (CAG)n allele were found.

Adult↗
PubMed1996

Hereditary neuropathy with liability to pressure palsies: the same molecular defect can result in diverse clinical presentation.

Hereditary neuropathy with liability to pressure palsies (HNPP) is a peripheral nerve disorder characterized by autosomal dominant inheritance, recurrent pressure palsies, reduced motor and sensory conduction velocities and sausage-like swellings (tomacula) of myelin sheaths in nerve biopsy. Two young adult patients are reported as index cases of two families in which HNPP was diagnosed. The first patient presented with recurrent pressure palsies, whereas the second suffered from fasciculations and myokymias in his right hand, with difficulty in writing, and upper and lower limb paraesthesias of 3 years' duration. Electrodiagnostic studies revealed slowing of conduction primarily in common sites of compression in both patients. Sural nerve biopsy revealed the characteristic tomaculous swellings in both patients. DNA analysis showed that both patients have a deletion in chromosome 17p11.2 which is found in the majority of HNPP cases. In light of the common molecular defect, the different clinical symptomatology of the two patients is discussed.

Adult↗
PubMed1996

Tumour necrosis factor alpha is elevated in serum and cerebrospinal fluid in multiple sclerosis and inflammatory neuropathies.

Tumour necrosis factor alpha (TNFalpha) is a peptide that is derived from T lymphocytes and macrophages and is used as a marker of activated cellular immune responses. TNFalpha was measured in paired sera and cerebrospinal fluid (CSF) from 30 patients with multiple sclerosis (MS) with worsening disability, 54 patients with other neurological diseases, and 20 normal subjects. A sensitive enzyme-linked immunosorbent assay was used to determine the TNFalpha levels. We found significantly elevated serum and CSF levels in 12 (40%) and 6 (20%) MS patients, respectively, compared with healthy controls (P < 0.007 and P < 0.05). Among the 18 patients with neuropathy, we also found high serum and CSF TNFalpha values in 3 (17%) and 5 (28%) patients, respectively (P < 0.04 and P < 0.002). Our study shows that TNFalpha is probably involved in the pathogenetic mechanisms of MS and other inflammatory neurological diseases.

Adolescent↗
PubMed1996

Cortical potentials with antisaccades.

The term antisaccade refers to saccades that are performed towards the side opposite to that of target appearance. The performance of antisaccades is considered to be determined by intact frontal inhibitory areas as patients with frontal, and especially prefrontal, lesions show a striking impairment in suppressing an unwanted protarget saccade. We recorded cortical slow potentials from subjects performing saccades and antisaccades in a task, antitask and no move conditions in order to investigate possible topographic differences between these two types of eye movement. Our main findings concern both movement related as well as sensory related potentials. With regard to the saccadic potentials, performance of an antisaccade is preceded by a much more pronounced activity during the last 100 ms prior to the eye movement onset over central-anterior leads with a slight ipsilateral lateralization. As for the sensory potentials, the target related with antisaccade performance is followed by smaller, but nonstatistically significant, exogenous responses while at 300-350 ms after target appearance, the activity associated with the antisaccade's target is clearly larger over central midline leads. Although we could not precisely relate the electrical activity obtained with well circumscribed cortical function, the results support the view that the anterior and slightly ipsilateral cortical activation which precedes the performance of an antisaccade could reflect the frontal mechanisms of suppression of the unwanted saccade.

Adult↗
PubMed1996

Two more secondary headaches mimicking chronic paroxysmal hemicrania. Is this the exception or the rule?

Two patients with headaches meeting the criteria of chronic paroxysmal hemicrania, as defined by the International Headache Society classification, are presented. Further investigations revealed a parasellar pituitary microadenoma in the first patient and a maxillary cyst in the second. Surgical removal of the lesions resulted in complete relief from headaches. The clinical features of this rare syndrome are discussed and suggest that a more detailed laboratory study and clinical follow-up is necessary in patients with chronic paroxysmal hemicrania.

Adenoma↗
PubMed1996

GHQ-28 as an aid to detect mental disorders in neurological inpatients.

The prevalence of mental disorders (DSM-IIIR criteria) among 107 neurological inpatients was estimated, as well as the extent to which disorders were detected by neurologists. The validity of the scaled version of the General Health Questionnaire (GHQ-28) was evaluated using Receiver Operating Characteristic (ROC) analysis and DSM-IIIR as external criteria. Of the 107 patients who submitted to a structured psychiatric interview (SCID-R), 56 (52.3%) showed evidence of a mental disorder. Major depressive episode (n = 16), generalized anxiety disorders (n = 13) and dysthymia (n = 12) were the most frequent diagnoses. The neurologists recognized only 13/107 cases (12.1%). Significantly more women than men exhibited some form of mental disorder. The validation of GHQ-28 in the series of 107 neurological inpatients indicated that the best trade-off between sensitivity and specificity was the cut-off score of 5/6. The high occurrence of mental disorder, in association with the low rate of detection by the neurologists, points to the need for special attention to be paid to this problem by staff and experts.

Adjustment Disorders↗
PubMed1996

Exclusion of one pedigree affected by adult onset primary open angle glaucoma from linkage to the juvenile glaucoma locus on chromosome 1q21-q31.

A locus for autosomal dominant juvenile onset primary open angle glaucoma (POAG) was recently assigned to chromosome region 1q21-q31. In the present study, a large Greek family with autosomal dominant adult onset POAG was investigated using microsatellite markers. Exclusion of linkage of the adult onset POAG gene to the region D1S194-D1S191 was obtained in this pedigree. Therefore, the data provide evidence that juvenile and adult onset POAG are genetically distinct disease entities.

Adult↗
PubMed1995

The role of water molecules in the structure-based design of (5-hydroxynorvaline)-2-cyclosporin: synthesis, biological activity, and crystallographic analysis with cyclophilin A.

Analysis of the contact surface of the cyclophilin A (CypA)/cyclosporin A (CsA, 1) crystal structure delineates a unique cavity between both molecules in the vicinity of the Abu-2 side chain atoms of 1 (Abu pocket). Therefore, (5-hydroxynorvaline)-2-cyclosporin (2) was designed and prepared as a CsA derivative which could mediate additional interactions within the pocket. The X-ray crystal structure of the CypA/2 complex at 1.76 A resolution shows that 1 and 2 have identical backbone conformations and that the introduced hydroxypropyl chain makes indeed the expected supplemental interactions with CypA. However, 2 has 8-9-fold lower binding affinity than 1 for CypA. This results from a presumed unfavorable free energy change associated with the displacement of one of the tightly bound water molecules within the pocket and a change in prebinding equilibria. The role of the later was assessed by comparing the conformation distribution of 1 and 2 to that of norvaline-2-cyclosporin (3) and norvaline-2-(D-MeSer)-3-cyclosporin (4).

Amino Acid Isomerases↗