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Biomedical subjects

M Georgopoulos

Publications and source records attributed to M Georgopoulos.

35 records · Page 2Linked to original sources
PubMed1999

Fractionated stereotactic radiotherapy with linear accelerator for uveal melanoma--preliminary Vienna results.

PURPOSE: To study local tumor control and radiogenic side-effects after fractionated stereotactic radiotherapy for uveal melanoma. PATIENTS AND METHODS: Between June 1997 and February 1998, 21 patients suffering from uveal melanomas have been treated with stereotactic 6 MeV LINAC (Saturne 43, General Electric, France) in conjunction with a stereotactic frame system (BrainLAB, Germany). Immobilization of the eye was ensured with an optical fixation system which was proven reliable. During radiotherapy, movements of the irradiated eye were controlled on a monitor and documented by video recording. All patients co-operated very well with the optical fixation system. In 1164 measurements, the median value of horizontal deviation of the diseased eye during treatment was 0.3 mm (range: 0 to 1.3 mm). Median vertical deviation was 0.2 mm (range: 0 to 1.2 mm). For all patients, mean tumor prominence before treatment was 6.0 +/- 2.2 mm. In 20 patients, the total dose of 70 Gy (at 80%) was delivered in 5 fractions within 10 days. In one patient with a ciliary body tumor, the total dose of 70 Gy was divided into 7 fractions for better sparing of the anterior eye segment. RESULTS: After a follow-up of at least 6 months, local tumor control was seen in all eyes. Mean tumor thickness reduction after 3, 6 and 9 months was 7%, 13% and 31%, respectively. Up to now, only mild subacute side-effects located in the anterior eye segment have been noticed. CONCLUSION: Optical fixation of the eye allows high precision stereotactic radiotherapy with small safety margins. Fractionated stereotactic radiotherapy and 70 Gy total dose delivered in 5 fractions seems to be appropriate for local tumor control in uveal melanoma. Further long-term studies with extended number of patients will be necessary to conclude on the use of linac-based fractionated stereotactic radiotherapy for uveal melanoma.

Austria↗
PubMed1999

Effects of peribulbar anesthesia on ocular blood flow in patients undergoing cataract surgery.

PURPOSE: The effects of extraconal, peribulbar anesthesia on ocular blood flow may be caused by concomitant elevations in intraocular pressure or direct pharmacologic alteration of vascular tone. We quantified the effect on ocular circulation with a new technique for assessment of ocular hemodynamics. METHODS: In a prospective study, ocular hemodynamics were measured before and 1 and 5 minutes after peribulbar anesthesia in 22 eyes with age-related cataract. Measurements included fundus pulsation amplitude with a laser interferometric method assessing the pulsatile choroidal blood flow and mean blood flow velocity as well as resistive index in the ophthalmic and central retinal artery with Doppler sonography. Systemic blood pressure and pulse were monitored throughout the period of ocular hemodynamic measurements. RESULTS: Fundus pulsation amplitude decreased significantly after peribulbar anesthesia (after 1 minute and 5 minutes: -13% and -8%; P < .001). In the central retinal artery, mean blood flow velocity dropped (-15%; P < .001) and resistive index increased (+3%; P = .02) 1 minute after peribulbar anesthesia compared with baseline. There were no changes in ophthalmic artery hemodynamics. Intraocular pressure was elevated 1 minute after peribulbar anesthesia (+29%; P = .003) but reached baseline values after 5 minutes. CONCLUSION: Pulsatile choroidal blood flow and retinal blood flow velocities were reduced after peribulbar anesthesia. These reductions were still present 5 minutes after peribulbar anesthesia, when intraocular pressure had returned to baseline values. This supports the theory of drug-induced vasoconstriction after peribulbar anesthesia. A loss of vision may be a risk of peribulbar anesthesia in patients who have compromised ocular blood flow before surgery.

Adult↗
PubMed1999

Changes in intraocular lens position after neodymium: YAG capsulotomy.

PURPOSE: To quantify changes in intraocular lens (IOL) position caused by neodymium: YAG (Nd:YAG) capsulotomy with 3 IOL styles. SETTING: Department of Ophthalmology, University of Vienna, Austria. METHODS: In a prospective study, anterior chamber depth (ACD) was measured by dualbeam partial coherence interferometry (PCI) in 32 pseudophakic eyes of 32 patients with posterior capsule opacification before and immediately after planned capsulotomy under mydriasis. Patients were divided into 3 groups with the following IOL styles: 1-piece poly(methyl methacrylate) (PMMA), 3-piece foldable, and plate haptic. RESULTS: The capsulotomy induced a backward IOL movement in all 32 eyes (mean 25 microns; range 9 to 55 microns). It was more pronounced in eyes with plate-haptic IOLs than in those with the other styles. Precision of ACD measurement by PCI was 4 microns. Changes in ACD correlated significantly with capsulotomy size but not with preoperative lens-capsule distance. CONCLUSION: Capsulotomy caused a backward movement of the IOL, which was more pronounced with plate-haptic IOLs than with 1-piece PMMA and 3-piece foldable IOLs. Since the magnitude of IOL movement in this study population was small, a hyperopic shift in refraction after capsulotomy will usually be small and not clinically relevant.

Adult↗
PubMed1999

Contact zone of piggyback acrylic intraocular lenses.

In a hyperopic cataract patient, surgery was performed with implantation of 2 foldable, acrylic, posterior chamber intraocular lenses (IOLs) in the bag. The IOLs showed a central contact zone during surgery. This contact zone remained after surgery and was documented 2 months postoperatively. The contact zone may induce multifocality similar to that seen with multifocal IOLs.

Acrylic Resins↗
PubMed1999

Effect of small incision cataract surgery on ocular blood flow in cataract patients.

PURPOSE: To evaluate the effect of small incision cataract surgery using peribulbar anesthesia on ocular blood flow in patients with senile cataract. SETTING: Department of Ophthalmology, University of Vienna, Vienna, Austria. METHODS: In 33 eyes of 33 consecutive patients scheduled for cataract surgery, ocular hemodynamics were measured preoperatively and 1 day, 1 week, and 1 month postoperatively. Measurements included fundus pulsation amplitude (FPA) with a laser interferometric method that assessed the pulsatile choroidal blood flow, mean blood flow velocity (MFV), and resistive index (RI) in the ophthalmic artery (OA) and the central retinal artery (CRA) with Doppler sonography. Systemic hemodynamics and intraocular pressure (IOP) also were measured. RESULTS: The FPA, MFV, and RI in the OA and the CRA did not change postoperatively from baseline values. Systemic hemodynamics, IOP, and as a consequence ocular perfusion pressure, also remained unchanged. CONCLUSION: Uneventful small incision cataract surgery using peribulbar anesthesia did not affect ocular blood flow in patients with senile cataract between 1 day and 1 month postoperatively.

Adult↗
PubMed1999

Effect of dorzolamide and latanoprost on intraocular pressure after small incision cataract surgery.

PURPOSE: To evaluate the effect of dorzolamide 2% and latanoprost 0.005% on intraocular pressure (IOP) after small incision cataract surgery. SETTING: Department of Ophthalmology, University of Vienna, Vienna, Austria. METHODS: This prospective study comprised 102 eyes of 102 consecutive patients scheduled for small incision cataract surgery. The patients were assigned preoperatively to 1 of 3 groups of 34 each: dorzolamide, latanoprost, and control (no treatment). One drop of the assigned medication was instilled immediately after surgery. Intraocular pressure was measured preoperatively and 6 and 20 to 24 hours postoperatively. RESULTS: Six hours after surgery, the mean increase in IOP was 1.9 mm Hg +/- 3.9 (SD) in the dorzolamide group (P = .004 versus control), 2.2 +/- 3.0 mm Hg in the latanoprost group (P = .005 versus control), and 4.8 +/- 5.2 mm Hg in the control group. Twenty to 24 hours postoperatively, IOP decreased a mean of -0.9 +/- 3.5 mm Hg in the dorzolamide group (P = .012 versus control) and increased a mean of 0.3 +/- 3.6 mm Hg in the latanoprost group (P = 0.24 versus control) and 1.3 +/- 4.2 mm Hg in the control group. One eye in the dorzolamide group, 1 eye in the latanoprost group, and 4 eyes in the control group had an IOP of 30 mm Hg or higher 6 hours postoperatively. CONCLUSION: Six hours postoperatively, dorzolamide and latanoprost were effective in reducing the IOP increase after small incision cataract surgery; however, at 20 to 24 hours, only dorzolamide was effective. Neither drug prevented IOP spikes of 30 mm Hg or higher.

Aged↗
PubMed1999

Ocular arterial blood flow of choroidal melanoma eyes before and after stereotactic radiotherapy using Leksell gamma knife: 2 year follow up.

AIMS: To evaluate the effect of high dose stereotactic radiotherapy on the ocular blood flow of patients with uveal melanoma. METHODS: Colour Doppler imaging (CDI) was used to measure blood flow velocity and vascular resistance in the ophthalmic, short posterior, and central retinal arteries of nine patients suffering from uveal melanoma. The measurements were taken before, 6 months, 1 year, and 2 years after stereotactic radiotherapy. Irradiation was performed with the Leksell gamma knife with the 59 (41-66.5) Gy total marginal dose divided in two equal fractions. CDI results were compared with age and sex matched healthy control eyes. RESULTS: At each time of measurement, blood flow velocity in the central retinal artery of the affected eyes was significantly reduced whereas vascular resistance was only increased at the 2 year follow up. Blood flow velocity and vascular resistance in the short posterior arteries of melanoma eyes were also only significantly altered at the 2 year follow up. Blood flow velocity and vascular resistance in the ophthalmic artery of melanoma eyes were not changed at all follow ups. CONCLUSIONS: In the melanoma eyes, blood flow velocity in the central retinal artery is reduced. High dose stereotactic radiotherapy with the Leksell gamma knife and a 59 (41-66.5) Gy total marginal dose in two fractions leads to a significant reduction of blood flow and a significant increase in resistance variables in the small ocular arteries within 2 years.

Adult↗
PubMed1999

[Idiopathic sclero-choroid calcification].

BACKGROUND: Idiopathic sclerochoroidal calcification (ISC) is an unusual, benign disorder occurring at the level of the posterior choroidea and sclera. Clinical differential diagnosis includes choroidal osteoma, choroidal metastasis, choroidal melanoma, choroidal amelanotic naevus and choroiditis. PATIENT: A 61-year old man was referred with the diagnosis of multifocal choroidal tumor in both eyes. Fundoscopy showed bilateral yellow lesions located near the superotemporal arcade. RESULTS: Fluorescein angiography shows the late staining of the choroidal lesions. Ultrasonographically highly reflective lesions (sclerochoroidal placoid lesions at the sclero-choroidal interface in the CT) confirms the clinical diagnosis. The serum calcium and phosphate metabolism is normal. CONCLUSION: The Idiopathic Sclerochoroidal Calcification (ISC) is a rare echographical differential diagnosis to the choroidal osteoma. ISC is a heterotopic calcification of the posterior pole in both eyes, usually located near the superotemporal arcade.

Calcinosis↗
PubMed1997

Bacterial growth in human vitreous humor.

The aim of this study was to investigate the capacity of human vitreous to support bacterial growth and to show differences in the growth kinetics of gram-positive and gram-negative bacteria. Vitreous gel of 70 keratoplasty donor eyes was sampled under sterile conditions, screened microscopically for cellular components and tested for sterility and levels of antibiotic drugs by bio-assay. The samples were inoculated with clinical isolates of Pseudomonas aeruginosa, Klebsiella pneumoniae, Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus viridans and Streptococcus pyogenes. As control each strain was added both to 0.9% sodium chloride solution and to Mueller-Hinton broth. In order to determine bacterial growth the number of colony forming units was determined 4, 6, 24, 48 and 72 hr after inoculation by viable count. Vitreous gel did not support bacterial growth; the tested strains could not be recovered after 48 hr. Similar results could be obtained with sodium chloride; whereas in Mueller Hinton broth the strains showed normal pattern of growth. It seems that vitreous humor has inherent antibacterial capacity in vitro, although the responsible factors remain unknown.

Aged↗
PubMed1996

Evaluation of asymptomatic microscopic haematuria--influence and clinical relevance of osmolality and pH on urinary erythrocyte morphology.

OBJECTIVE: To determine whether the morphological distinction between 'dysmorphic' and 'eumorphic' erythrocytes in urinary sediment differentiates microscopic haematuria (MH) from reno-parenchymal and post-renal bleeding. MATERIALS AND METHODS: The erythrocyte morphology of 2145 urinary sediments from 1391 patients with MH was evaluated by interference-contrast microscopy and compared with the osmolality, pH and specific gravity of the urine samples. RESULTS: Compared with more concentrated urine specimens, samples of < 700 mOsmol/kg showed significantly lower percentages of dysmorphic erythrocytes; there was a similar reduction in this percentage at a pH > or = 7. In addition, erythrocytes lysed in diluted or alkaline urine and therefore, under these conditions, no diagnosis could be made. CONCLUSION: The assessment of erythrocytes in urinary sediment should be performed only under 'standard conditions', i.e. in concentrated and acidic urine, > or = 700 mOsmol/kg and a pH < 7. The presence of > or = 90% dysmorphic erythrocytes in patients with asymptomatic MH, the absence of proteinuria, a normal blood pressure and normal radiological examination indicates 'reno-parenchymal MH', requiring a long-term follow-up with a routine evaluation twice a year, but no immediate treatment in most cases. In contrast, the presence of > or = 90% eumorphic erythrocytes or even 'mixed' results (10-90% eumorphic erythrocytes) indicates 'post-renal MH', requiring a complete urological evaluation.

Decision Trees↗
PubMed1992

Antibacterial activity of sparfloxacin against experimental renal infections in mice.

In a murine model of renal infection (Staphylococcus aureus and Escherichia coli), sparfloxacin was compared with ciprofloxacin and fleroxacin. After intrarenal inoculation, mice were treated orally for 5 days. The drugs were administered at five different dosages, ranging from 3.125 to 50 mg/kg of body weight per day for S. aureus and from 0.78 to 12.5 mg/kg/day for E. coli. Evaluation of efficacy was based on the proportional reduction of bacterial counts in the kidney tissues of treated animals compared with those of untreated control animals. For S. aureus, the doses required to clear the infection in 50% of mice were as follows: sparfloxacin, 10 mg/kg/day; ciprofloxacin, 33 mg/kg/day; and fleroxacin, 16 mg/kg/day. For E. coli renal infection, the corresponding dosages were as follows: sparfloxacin, 1.5 mg/kg/day; ciprofloxacin, 2.45 mg/kg/day; and fleroxacin, 1.8 mg/kg/day. Sparfloxacin and fleroxacin have a lower effective dose than ciprofloxacin in these models, probably because ciprofloxacin has a shorter serum half-life than the other two compounds.

Abscess↗
PubMed1991

[Epidemiology and pathogen spectrum of urinary tract infections].

Urinary tract infections still are a diagnostic as well as a therapeutical problem. The knowledge on the frequency of the causative organisms and their sensitivity to antibiotics and the different modes of urinary tract infections as well are very important, especially because of remaining organizational and medical-technical problems to identify the organisms. E. coli-bacteria are up to now the most frequent pathogens of urinary tract infections, with a resistance rate of 30% against aminopenicillins. An increase of resistant Enterobacter- and Pseudomonas-aeruginosa-strains against quinolones is known and could be observed also in our hospital. The demand for knowledge of sensitivity pattern of the causative organisms still remain for a successful antibiotic therapy.

Adolescent↗
PubMed1990

The persistent trigeminal artery and its topographical relations.

The topographical relation of a persistent trigeminal artery (PTA) to neighboring structures was investigated. The vessel belongs to Saltzman's type I. It originates from segment C5 of the internal carotid artery and opens into the basilar artery, 8 mm before the bifurcation into the two posterior cerebral arteries. The 6th cranial nerve winds around the first part of the PTA which is situated within Parkinson's triangle.

Aged↗
PubMed1989

Value of urinary erythrocyte morphology in assessment of symptomless microhaematuria.

To assess the value of microscopic analysis of urinary erythrocyte morphology as the initial step in the investigation of patients with isolated symptomless microhaematuria, 316 consecutive patients were grouped according to whether they excreted eumorphic or mixed forms of erythrocytes or only dysmorphic forms. The former group was investigated fully, and urological disease was found in 85% of 123 patients. The 192 patients with exclusively dysmorphic erythrocytes in their urine and normal renal function (benign renal microhaematuria) were assigned to annual follow-up examinations of urinary red cell morphology and renal function, and subjected to invasive diagnostic procedures when a change was noted. In only 2 of the 132 patients followed up for at least 2 years did a new disease develop; this was easily identified at one of the annual examinations. Microscopic analysis of urinary erythrocyte morphology is therefore an effective method for identifying patients with symptomless microhaematuria needing specific diagnostic investigation.

Adolescent↗
PubMed1988

In-vitro activity of fleroxacin.

Fleroxacin is a new synthetic fluorinated quinolone antimicrobial agent. The in-vitro activity of fleroxacin and five comparative quinolones against 541 clinical isolates was studied. Minimum inhibitory concentrations (MIC90) of fleroxacin were less than or equal to 2.0 mg/l for Enterobacteriaceae, less than or equal to 8.0 mg/l for Pseudomonas aeruginosa and 1.0 mg/l for Acinetobacter calcoaceficis and 8 mg/l for streptococci. The activity of fleroxacin was comparable with that of ofloxacin, pefloxacin and norfloxacin, but less than that of ciprofloxacin. All quinolones showed little difference between MIC and minimum bactericidal concentrations (MBCs).

Anti-Infective Agents↗
PubMedDate not supplied

Antimicrobial activity of josamycin against erythromycin-resistant staphylococci as compared to roxythromycin and clarithromycin.

In an in vitro study 246 clinical isolates of erythromycin-resistant staphylococci from six hospitals in Austria were investigated for susceptibility to josamycin and other, newer macrolide antibiotics, e.g. roxithromycin and clarithromycin. 71 strains of Staphylococcus aureus showed an MIC > or = 4 mg/l and 100 strains of S. aureus showed an MIC > or = 256 mg/l. In addition, 25 strains of coagulase-negative staphylococci resistant to erythromycin at an MIC of > or = 4 mg/l were investigated. At an MIC of 2 mg/l 57% of the erythromycin-resistant strains of S. aureus were inhibited by josamycin, 25% by clarithromycin and 11.6% by roxithromycin. At an MIC of 2 mg/l 13.3% of erythromycin-resistant coagulase-negative staphylococci were inhibited by josamycin, 10.7% by clarithromycin and 9.3% by roxithromycin. This study suggests that josamycin is still active in vitro against more than 50% of erythromycin-resistant strains of S. aureus. This drug is also more active than roxithromycin and clarithromycin against erythromycin-resistant S. aureus.

Clarithromycin↗