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Biomedical subjects

G Polizzi

Publications and source records attributed to G Polizzi.

At least 19 recordsLinked to original sources
PubMed2000

Recovery of visual field constriction following discontinuation of vigabatrin.

Epilepsy patients treated with vigabatrin may develop symptomatic or asymptomatic concentric visual field constriction due to GABA-associated retinal dysfunction. The prevalence and course of this side effect are not established yet; in previously reported adult patients the visual disturbances seem to be irreversible. We present two patients with a significant improvement of visual field constriction and retinal function after the discontinuation of vigabatrin. These findings suggest that vigabatrin-associated retinal changes are at least partly reversible in some patients, and that these patients may benefit significantly from a withdrawal of vigabatrin. Larger scale clinical studies are needed to identify predictive factors both for the occurrence and reversibility of vigabatrin-associated visual field defects.

4-Aminobutyrate Transaminase↗
PubMed2000

Long-term retention rates of lamotrigine, gabapentin, and topiramate in chronic epilepsy.

PURPOSE: We sought to determine the long-term retention rates of lamotrigine (LTG), gabapentin (GBP), and topiramate (TPM) therapy for patients at a tertiary referral clinic for chronic, refractory epilepsy. METHODS: We analyzed 424 consecutive patients with chronic, refractory partial and/or generalized epilepsy who were started on LTG, 158 patients who were started on GBP, and 393 patients who were started on TPM. The percentages of patients who continued therapy with LTG, GBP, and TPM were estimated with the use of Kaplan-Meier survival analysis. Factors that influence retention were analyzed with the use of Cox regression analysis. RESULTS: Kaplan-Meier survival analysis showed that at 3 years, 30% continued therapy on TPM compared with 29% on LTG and fewer than 10% on GBP. Adverse events resulted in therapy withdrawal in 40% of patients on TPM compared with GBP (37%) and LTG (22%). Perceived lack of efficacy led to treatment withdrawal in 39% of patients on GBP compared with 34% on LTG and 19% on TPM. Cox regression estimated that a fourth or fewer of patients with chronic partial epilepsy are likely to continue therapy with a new antiepileptic drug beyond 5 years. CONCLUSIONS: The impact of these new antiepileptic drugs on the long-term course of chronic partial epilepsy is likely to be small, as approximately three of four patients will discontinue therapy. More patients appear to continue on TPM compared with LTG or GBP, with a possible reason being better perceived efficacy of TPM, despite having the highest incidence of adverse events.

Acetates↗
PubMed2000

Brånemark System Wide Platform implants for single molar replacement: clinical evaluation of prospective and retrospective materials.

BACKGROUND: The use of oral implants for single tooth replacement has become a predictable treatment modality. As single tooth loss is most common in posterior areas of the jaws, the use of the protocol is of specific interest in those regions. New implant designs aimed at this purpose have also been introduced. PURPOSE: The aim of the study was to present the outcomes for wide diameter implant treatment when being used in posterior areas of the jaws. MATERIALS AND METHODS: This paper presents the 3-year results of a prospective multicenter study (three clinics; n = 38 implants) and the 1-year results from a retrospective multicenter study (two clinics; n = 20 implants) on wide diameter implants for single molar replacement. Based on the hypothesis that dense bone in posterior mandibles would benefit from careful surgery and longer remodeling time, the influences of surgical technique and healing time on implant success and bone resorption were particularly addressed. RESULTS: The outcome demonstrated a good predictability for Brånemark System Wide Platform implants, at least short term, when used as single molar support (prospective group cumulative success rate [CSR] = 92% after 3 years; retrospective group CSR = 95% after 1 year). The increased mechanical strength of the wide platform implant/abutment complex also turned out to be important for mechanical stability. CONCLUSIONS: The study indicated that it was important to carefully perform surgery in posterior mandibles in order to preserve and optimally use the existing dense bone. It was suggested that from bone healing and remodeling aspects, posterior mandibles may be more demanding to handle than corresponding areas of maxillae.

Adult↗
PubMed2000

Immediate and delayed implant placement into extraction sockets: a 5-year report.

BACKGROUND: As a complement to the earlier reported 3-year results from a prospective multicenter study of immediate and delayed placement of implants into fresh extraction sockets, the 5-year results are reported. PURPOSE: The purpose of this 5-year report was to evaluate the immediate and long-term success of implants placed into fresh extraction sockets, with respect to implant size and type, bone quality and quantity, implant position, initial socket depth, and reason for tooth extraction. MATERIALS AND METHODS: This paper presents the 5-year results of the original 12 centers that participated with 143 consecutively included patients. A total of 264 implants were placed either immediately after tooth extraction or after a short soft-tissue healing time (3-5 weeks). The patients were divided into five subgroups, depending on the type of insertion method used. RESULTS: The outcome demonstrated that the cumulative implant survival rate after 5 years of loading has not changed and remains 92.4% in the maxilla and 94.7% in the mandible. No difference in failure rates can be seen between the groups when relating the failures to insertion method. CONCLUSION: This prospective study demonstrated that placing Brånemark implants into fresh extraction sites can be successful over a period of 5 years of loading. One of the outcomes of the study shows that there is a clinical correlation between implant failure and periodontitis as a reason for tooth extraction, even if it is difficult to give it a casual association. It can be hypothesized that periodontitis affected tissues might have a negative local influence because of the presence of infrabony defects that could possibly increase the gap between bone and implant or jeopardize achievement of primary stability.

Bone Density↗
PubMed1999

Reproducible localization of interictal epileptiform discharges using EEG-triggered fMRI.

We report preliminary experiences using fMRI triggered by EEG to localize the site of interictal epileptiform activity. EEG was recorded in the scanner and monitored on-line; the recording quality was good enough to allow the clear identification of spikes in the EEG. Snap-shot EPI was performed 2-4 s after an epileptiform discharge ('spike') or after at least 10 s of background activity ('rest') was observed. A pixel-by-pixel t-test was performed between the 'rest' and the 'spike' images to determine areas of significant activation. Significant activation was obtained in a patient with epilepsy. To assess the reliability and reproducibility of the technique, the patient was scanned on four separate occasions with similar areas being activated in all the studies, confirming the validity of the result.

Brain↗
PubMed1998

Identification of EEG events in the MR scanner: the problem of pulse artifact and a method for its subtraction.

Triggering functional MRI (fMRI) image acquisition immediately after an EEG event can provide information on the location of the event generator. However, EEG artifact associated with pulsatile blood flow in a subject inside the scanner may obscure EEG events. This pulse artifact (PA) has been widely recognized as a significant problem, although its characteristics are unpredictable. We have investigated the amplitude, distribution on the scalp, and frequency of occurrence of this artifact. This showed large interindividual variations in amplitude, although PA is normally largest in the frontal region. In five of six subjects, PA was greater than 50 microV in at least one of the temporal, parasagittal, and central channels analyzed. Therefore, we developed and validated a method for removing PA. This subtracts an averaged PA waveform calculated for each electrode during the previous 10 s. Particular attention has been given to reliable ECG peak detection and ensuring that the average PA waveform is free of other EEG artifacts. Comparison of frequency spectra for EEG recorded outside and inside the scanner, with and without PA subtraction, showed a clear reduction in artifact after PA subtraction for all four frequency ranges analyzed. As further validation, lateralized epileptiform spikes were added to recordings from inside and outside the scanner: PA subtraction significantly increased the proportion of these spikes that were correctly identified and decreased the number of false spike detections. We conclude that in some subjects, EEG/fMRI studies will be feasible only using PA subtraction.

Adult↗
PubMed1998

Diagnosis of renovascular disease by extra- and intrarenal Doppler parameters.

It is still a matter of debate as to which parameters should be used for noninvasive diagnosis of renovascular disease by renal Doppler sonography (RDS). The accuracy of RDS in the detection of renal artery stenosis (RAS) was tested in 95 consecutive, moderate to severe hypertensive patients (I-II World Health Organization [WHO] stages). Reno-aortic ratio (RAR) for peak systolic velocity (PSV) was also calculated to assist in the diagnosis of significant (>50%) RAS. Paired receiver-operating characteristic (ROC) analysis was plotted for evaluating the relationship between sensitivity and specificity for each parameter. In a subset of 57 kidneys, the influence of blood pressure and age on intraparenchymal parameters was evaluated. Measurements of maximal peak systolic velocity (PSV) at the site of stenosis, RAR for PSV, and minimum acceleration index in the main renal artery showed high accuracy (areas under the ROC curve 0.97, 0.88, and 0.80, respectively). Among intraparenchymal parameters, early systolic acceleration showed the best area under the ROC curve (0.90), but provided a low positive predictive value (29%) and was significantly influenced by blood pressure (multiple r=0.56; p=0.001). Pulsatility and resistive indices were found to be less powerful as absolute values, and both significantly influenced by blood pressure and age (multiple r=0.60 and 0.50; p=0.001, p=0.02, respectively). However, interindividual variance of intrarenal indices should be minimized by calculation of side difference, although this procedure would become misleading or impossible in patients with bilateral RAS or a single kidney, respectively. These results support the use of extraparenchymal parameters for noninvasive detection of RAS, and emphasize that intrarenal parameters cannot be considered as absolute values.

Adult↗
PubMed1996

Raised plasma endothelin-1 concentrations in patients with primary hypercholesterolemia without evidence of atherosclerosis.

The present study was designed to investigate the pattern of circulating endothelin-1 (ET-1), a potent vasoconstricting mitogenic endothelium-derived peptide, in relation to primary increase in serum cholesterol in humans. We measured plasma ET-1 concentrations by radioimmunoassay (Amersham, UK) in 8 patients (6 females and 2 males, aged 42-62 years) with primary hypercholesterolemia, non-smokers, without evidence of cardiovascular disease, and in 8 healthy sex-and age-matched control subjects. The mean (+/- SD) values of serum total cholesterol, low-density-lipoprotein (LDL) cholesterol, high-density-lipoprotein (HDL) cholesterol and triglycerides in the hypercholesterolemic subjects were 7.2 +/- 1.1 mmol/L, 5.1 +/- 1.1 mmol/L, 1.0 +/- 0.1 mmol/L and 2.4 +/- 0.9 mmol/L, respectively. The lipid profile of the controls showed a total cholesterol of 4.6 +/- 0.3 mmol/L, LDL cholesterol of 3.0 +/- 0.2 mmol/L, HDL cholesterol of 1.0 +/- 0.1 mmol/L and triglycerides of 1.2 +/- 0.2 mmol/L. The mean ET-1 plasma levels in the hypercholesterolemic patients were significantly higher than in the controls (4.2 +/- 0.1 pmol/L and 2.2 +/- 0.7 pmol/L, respectively, p < 0.001). Our data of raised circulating ET-1 in hypercholesterolemic patients without evidence of atherosclerosis suggest that an exaggerated release of ET-1 could contribute: 1) to impair endothelium-dependent vasodilation; 2) to promote the atherogenic process in hypercholesterolemia. Finally, it could represent a marker for hypercholesterolemic endothelial damage.

Adult↗
PubMed1996

Vertical ridge augmentation: what is the limit?

The aim of this study is to show the possibility of achieving more than a 4-mm new vertical bone apposition on partially edentulous ridges. Six healthy, partially edentulous patients were treated from July 1993 to September 1993. After accurate radiographic investigation, all of the patients were treated using the Branemark System. After insertion, 14 fixtures were left circumferentially exposed for 37 mm. Autogenous bone graft harvested from a bone filter was placed around the exposed threads and completely covered with titanium-reinforced Gore-Tex augmentation membranes (TR-GTAM). Flaps were coronally displaced to passively cover the regenerative materials. Only one of the six membranes was exposed and it was removed immediately. After a 12-month healing period, the membranes were removed in conjunction with the second-stage surgical procedure. In the five cases where the membranes were kept covered, all of the available space underneath the TR-GTAM was filled with regenerative tissue. In all of the cases a histologic biopsy was performed. In one case all the space was filled with more than 7 mm of bone. In three cases all the space was filled with more than 5 mm of bone. In one case the most coronal part (approximately 1 mm) of the regenerative tissue was represented by connective tissue; the remaining tissue was represented by bone. The measurements demonstrated an average of vertical ridge augmentation of 4.95 mm. In the only case where the membrane underwent exposure and was then removed there was no regenerative tissue present.

Adult↗
PubMed1993

Atrial natriuretic peptide response to postural changes and upright exercise in patients with venous valvular insufficiency.

To investigate the effects of postural changes and upright exercise on atrial natriuretic peptide release and renin-angiotensin-aldosterone system behavior in patients with venous valvular insufficiency, plasma ANP, plasma renin activity and aldosterone were measured in 11 patients with venous disease and in 11 age-matched controls. In patients with large varicose veins and venous valvular dysfunction, standing was associated with a greater fall in circulating ANP levels (p < 0.05) and upright exercise was accompanied by a smaller rise in ANP concentrations (p < 0.05) as compared with controls. A significant (p < 0.001) inverse relationship was found between the number of venous segments with reflux and both upright and exercise plasma ANP concentrations (r = -0.91; r = -0.84, respectively). In the two groups the response of the renin-angiotensin-aldosterone system to upright position and physical stress was similar. These results suggest that a decreased atrial stretch, due to a reduced venous return, could account for the blunted ANP response to erect posture and exercise in patients with venous valvular incompetency.

Adult↗
PubMed1992

Transient myocardial ischemia stimulates atrial natriuretic factor release.

Atrial natriuretic factor release during transient myocardial ischemia was investigated in 29 patients with coronary artery disease and symptoms of angina (Canadian Cardiovascular Association classes II-III). Eleven patients (group I) underwent single-vessel percutaneous transluminal coronary angioplasty. Repeat determinations of mean pulmonary artery wedge pressure and blood sampling from pulmonary artery for atrial natriuretic factor measurements were performed at baseline, and at 2, 5, and 15 minutes after percutaneous transluminal coronary angioplasty was begun. Baseline atrial natriuretic factor levels (34.6 +/- 4.5 pg/ml) rose to 56.3 +/- 7.3 pg/ml (p = 0.02) and decreased at 5 minutes (43.7 +/- 5.7 pg/ml, not significant) and 15 minutes (35.3 +/- 4.4 pg/ml, not significant). Changes in atrial natriuretic factor concentrations were significantly correlated with those in mean pulmonary artery wedge pressure (2 minutes: r = 0.69, p = 0.02; 5 minutes: r = 0.90, p less than 0.001). In group II (n = 10) the increase in atrial natriuretic factor after dye load occurred later (baseline: 25.8 +/- 2.1; 60 minutes: 40.6 +/- 2.6 pg/ml; p = 0.005) than that observed in group I after percutaneous transluminal coronary angioplasty. In group III, atrial natriuretic factor during angina rose as early (baseline 11.3 +/- 1.3; 5 minutes: 20 +/- 2.3 pg/ml; p = 0.006) as after percutaneous transluminal coronary angioplasty. Results indicate that transient myocardial ischemia stimulates atrial natriuretic factor release, probably through changes in cardiac function.

Angina Pectoris↗
PubMed1992

Ischemia-induced changes in the immunoreactivity for endothelin and other vasoactive peptides in the brain of the Mongolian gerbil.

Immunoreactivity for vasoactive peptides [endothelin (ET); calcitonin gene-related peptide (CGRP); atrial natriuretic peptide (ANP); neuropeptide Y (NPY)] was investigated in nervous tissue of Mongolian gerbils in which the common carotid artery (CCA) was temporarily occluded (30 min-4 h) on one side, provoking transient unilateral ischemia at the forebrain level. Observations were carried out in a group of animals that were perfused promptly after CCA reopening, and in a group of animals that were perfused 12 h later. In animals of the first group, darker immunostaining was usually observed for most peptides in the forebrain ipsilateral to the CCA occlusion. Computer-assisted densitometric analysis showed that the asymmetry was relevant for ET, CGRP, and ANP, and almost undetectable for NPY. In animals of the second group, areas of tissue degeneration were observed. In these areas, ET immunoreactivity was markedly denser, whereas immunoreactivity for the remaining peptides was about at the background level. It is concluded that ischemia induces an increase in both vasoconstrictor and vasodilator peptides that in areas of moderate ischemia might maintain a residual tissue perfusion. In areas of severe hypoxia, a predominant ET-induced vasoconstriction would contribute to tissue damage.

Animals↗
PubMed1991

Osseointegrated implants for single tooth replacement: a 1-year report from a multicenter prospective study.

One hundred seven dental implants were inserted to support single tooth restorations in 92 patients participating in a prospective multicenter investigation. Only three implants (2.8%) were lost after 1 year of clinical function. Most of the remaining restorations were esthetically successful by using modified components. The gingival condition was healthy around the single crowns and coincided well with the clinical situation around the permanent teeth. The most obvious problem experienced during the first year was related to loose abutment screws. Twenty-six percent of the screws retaining crowns were retightened during the observation period, but the frequency of loose screws had a tendency to decrease as the study progressed.

Adult↗
PubMed1990

Comparison of ketanserin and enalapril in the treatment of mild-to-moderate essential hypertension.

In a double-blind 3-month study in mild-to-moderate essential hypertensive patients over 50 years of age, ketanserin, a selective S2-serotoninergic antagonist with additional alpha 1-adrenergic blocking properties, has been compared with enalapril, an angiotensin-converting enzyme inhibitor. Supine and upright blood pressures and heart rates were recorded for placebo and during active treatment (-4, -2, 0, 2, 4, 6, 8, 10, and 12 weeks). Metabolic profile (plasma glucose, creatinine, sodium, potassium, total and HDL-cholesterol, triglycerides, uric acid) was monitored during treatment with placebo and at the end of the study. Mean blood pressure was equally and significantly (p less than 0.001) lowered by both drugs from 2 weeks of treatment, whereas no changes occurred in mean heart rate or in biochemical variables. Dizziness was observed in three patients on ketanserin and in one patient on enalapril, whereas headache occurred in only one patient on enalapril. These data indicate that ketanserin is as effective and well tolerated as enalapril in hypertensive patients over 50 years of age.

Aged↗
PubMed1990

Baseline and post-atrial pacing release of atrial natriuretic factor in mitral stenosis.

To investigate the release of atrial natriuretic factor (ANF) in mitral stenosis and the influence of the increase on the frequency of atrial contraction or atrial distention on ANF secretion, we studied 10 patients with symptoms of congestive heart failure (New York Heart Association classes II and III) in sinus rhythm, who were undergoing cardiac catheterization as part of an evaluation workup for mitral stenosis. Echocardiographic tracings, repeat determinations of mean pulmonary artery wedge pressure (MPAWP) and mean right atrial pressure, and blood sampling from the pulmonary artery for measurements of ANF were performed at baseline, during atrial pacing (pacing rate of 125 beats/min for 5 minutes), and 5 minutes after the pacing protocol was completed. Baseline ANF levels were closely related to right atrial pressure (r = 0.89; p less than 0.001) and increased markedly after atrial pacing from 205.6 +/- 39.8 (SEM) to 343.9 +/- 57.9 (SEM) pg/ml. A similar pacing-induced increase was shown for MPAWP and left atrial size. Our data indicate that pacing-induced increases in atrial distention and intracavitary pressure further stimulate release of ANF. However, an independent effect of frequency of atrial pacing on plasma ANF in humans could not be identified.

Adult↗
PubMed1989

Evidence for a further stimulation of atrial natriuretic factor release by atrial pacing in patients with mitral stenosis.

To investigate the release of atrial natriuretic factor (ANF) in mitral stenosis and the effect of an increased atrial contraction frequency on atrial distension and ANF secretion, we studied 14 patients [New York Heart Association (NYHA) grades II-III] in sinus rhythm, undergoing cardiac catheterization for mitral stenosis. Echocardiographic tracings, repeat determinations of mean pulmonary artery wedge pressure and blood samples from the pulmonary artery for ANF measurements were taken at baseline, during atrial pacing (125 beats/min for 5 min) and 5 min after pacing. After pacing, ANF levels rose markedly with a parallel increase in mean pulmonary artery wedge pressure and left atrial size. These data indicate that atrial pacing is capable of further stimulating ANF release, even in patients with elevated baseline ANF and left atrial pressure and an increased left atrial dimension.

Adult↗
PubMed1988

Epidermal growth factor receptor in human breast cancer: correlation with steroid hormone receptors and axillary lymph node involvement.

Epidermal growth factor (EGF-R) estrogen (ER) and progesterone (PR) receptors were evaluated in 89 primary breast cancers and 23 axillary lymph node metastases. About 57% of primary and 72.2% of metastatic tumors were EGF-R positive and median EGF-R levels were higher in metastatic deposits than in primary breast tumors (P less than 0.05). An inverse distribution of EGF-R and steroid hormone receptor positive tumors was found (chi 2 = 10.87; P less than 0.001 for PR and chi 2 = 5.01; P less than 0.05 for ER) and an interesting correlation between EGF-R expression in primary tumor and axillary lymph node involvement was demonstrated (chi 2 = 21.4; P less than 0.001). Immunohistochemical studies with a monoclonal antibody against EGF-R revealed the presence of EGF-R only in malignant cells. Our data suggest that EGF-R could identify a class of more aggressive breast tumors endowed with a higher metastatic potential and may therefore represent an unfavorable prognostic parameter in breast cancer.

Adult↗