Search PubMed⌕ Search

Biomedical subjects

G Di Pasquale

Publications and source records attributed to G Di Pasquale.

At least 19 recordsLinked to original sources
PubMed1995

[A transient decrease in heart rate variability in patients with sudden "ischemic" death during Holter monitoring].

BACKGROUND: Mechanisms precipitating sudden death are poorly known, in spite of the importance to detect functional factors which may contribute to such fatal event. Aim of the study was to investigate the relationship between "ischemic" sudden death (ISD: arrhythmic death preceded by acute myocardial ischemia) and autonomic nervous system activity. METHODS: We analysed the tapes of 6 patients (pts) (5 males; 67 +/- 12 yrs) suffering ISD during Holter monitoring (HM). One pt had recent onset angina, 2 had unstable and 3 stable angina; none was taking antiarrhythmic drugs. Arrhythmias, ST segment and heart rate variability (HRV) were analysed by a computerized interactive HM system, in order to obtain data on transient ischemia and sympatho-vagal balance. RESULTS: Five pts showed ventricular tachyarrhythmias (2 VF, 3 VT), and 1 had a bradyarrhythmia (advanced A-V block) as the terminal event; all pts showed ST shift (max: 0.37 +/- 0.28 mV; 1 with ST elevation; 4 with anginal pain) 53 +/- 35 min before ISD. SD of normal R-R intervals (SDNN) was 112 +/- 26 msec in the 11 +/- 8 hrs of HM, whereas it was 97 +/- 48 msec in the initial hour and 59 +/- 21 msec in the initial 5 min segment. Measurements of SDNN showed a marked decrease 5 min before the onset of fatal ischemic ST shift: 32 +/- 14 msec (p = 0.003). Also, pNN50 (percent of adjacent R-R differing > 50 msec: marker of vagal activity) was significantly reduced before ISD, when compared to the initial 5 min segment (from 10 +/- 5 to 7 +/- 4%; p < 0.03). Such changes were not observed before uncomplicated (that is not associated with malignant arrhythmias) ST shift episodes during HM. CONCLUSIONS: Autonomic dysfunction, as detected by a marked decrease of HRV, is present in the period (5 min) immediately preceding the onset of ST shift precipitating ISD; simultaneous measurements of vagal signals showed similar changes. These data suggest that sympatho-vagal unbalance may trigger fatal arrhythmias during acute myocardial ischemia, hence resulting in ISD.

Aged↗
PubMed1994

Preoperative noninvasive coronary risk stratification in candidates for carotid endarterectomy.

BACKGROUND AND PURPOSE: Patients with symptomatic carotid stenosis who are candidates for carotid endarterectomy are at high short- and long-term risk of coronary events. To stratify patients at different risk of coronary events we investigated the usefulness of a noninvasive preoperative cardiological workup. METHODS: We studied 172 consecutive patients admitted to the Neurosurgical Department for symptomatic high-grade (70% to 99%) carotid stenosis (age, 42 to 74 years; mean, 57.8 years). Patients without history of coronary artery disease (CAD) and able to exercise were submitted to exercise electrocardiographic testing (EET) and, if abnormal, to exercise thallium myocardial imaging (TMI). Patients were classified into four groups: group 1, patients without CAD: no history of CAD, normal EET, or normal TMI in the presence of indeterminant EET (n = 93, 54%); group 2, patients with silent CAD: no history of CAD and concordant abnormal EET and TMI (n = 28, 16%); group 3, patients unable to exercise: no history of CAD and inability to perform adequate EET because of previous stroke or claudication (n = 29, 17%); and group 4, patients with known CAD: history of angina or myocardial infarction (MI) (n = 22; 13%). RESULTS: The four groups were comparable in regard to age, sex, and computed tomographic scan of the brain. The prevalence of stroke was higher in patients unable to exercise; hypercholesterolemia was more frequent in patients with known CAD. During the perioperative period (< or = 30 days after carotid endarterectomy), coronary events occurred in 3 patients (2%): fatal MI in 2 patients in group 4 and 1 patient in group 3. One hundred percent of patients were followed up for 6.2 years. Coronary events occurred in 23 of the 168 patients discharged from the hospital (13.7%); these were fatal in 11 (6.5%): 3 patients of group 1 (3%; sudden death in 2, fatal MI in 1), 8 patients of group 2 (29%; fatal MI in 5, unstable angina in 3), 8 patients of group 3 (28%; fatal MI in 4, nonfatal MI in 4), and 4 patients of group 4 (18%; fatal MI in 2, sudden death in 1, unstable angina in 1). Kaplan-Meier estimated curves of survival free from fatal and nonfatal coronary events were 97%, 51%, 49%, and 59%, respectively (P < .001, group 1 versus groups 2 and 3; P < .01, group 1 versus group 4). CONCLUSIONS: Among patients undergoing carotid endarterectomy, coronary events occurred twice as often as cerebral recurrences. A preoperative noninvasive cardiac investigation, including EET, can adequately identify groups of patients with diverse short- and long-term prognoses. In addition to patients with known CAD, those with silent CAD or who are unable to exercise represent, without the need of further investigation, groups at high risk of coronary events in long-term follow-up.

Adult↗
PubMed1994

Functional studies of E7 proteins from different HPV types.

We have performed comparative studies on the E7 proteins from malignant and non-malignant Human Papillomavirus types HPV 1, 6, 11, 16, 18, 33). GST/E7 fusion proteins from all these HPV types associate with Rb1, p107 and the cyclin A/CDK2 complex. As has been shown for Rb1, the association with p107 and Cyclin A was weaker for the 'low risk' HPV6 and 11 E7 proteins as compared to 'high risk' HPV16, 18 and 33 E7 proteins. In contrast the E7 protein of the benign type HPV1 bound Rb1, p107 and cyclin A with the same affinity as the 'high risk' E7 proteins. The affinities of the E7/Rb1 interaction have been confirmed in vivo by the 'two hybrid' method in the yeast Saccharomyces cerevisiae. Although HPV1 E7 showed the same affinity in vitro and in vivo for Rb1 as the high risk HPV E7s, it did not have the ability to activate the E2F-1 transcription factor inhibited by Rb1, nor did it have any transforming activity when coexpressed with activated ras in primary rodent cells.

Animals↗
PubMed1993

Cationic lipids improve antisense oligonucleotide uptake and prevent degradation in cultured cells and in human serum.

The power of antisense phosphodiester oligonucleotides (aODN) as regulatory molecules of gene expression is strongly limited by their low cellular uptake and very rapid nuclease-mediated degradation. This study deals with the effect of artificial cationic lipids on ODN cellular uptake and degradation in cell cultures and in human serum. At the ODN levels normally used in antisense-mediated gene regulation experiments, a cationic lipid, DOTAP, enhances the rate of ODN uptake more than 25 fold, but at lower ODN levels the effect of DOTAP is absent. These findings are consistent with a mechanism of ODN internalization by receptor-mediated saturable endocytosis that is bypassed by DOTAP. ODN degradation by nucleases is markedly prevented by DOTAP both in cultured cells and in human serum. Other cationic lipids, namely DOTMA and DOGS, exhibit very similar behaviour. The relatively slight cellular toxicity revealed by cationic lipids contribute to render these molecules very suitable for aODN vehiculation.

3T3 Cells↗
PubMed1993

New adenosine kinase inhibitors with oral antiinflammatory activity: synthesis and biological evaluation.

Several 5-iodotubercidin analogues in the pyrazolo[3,4-d]pyrimidine ring system were synthesized as potential inhibitors of adenosine kinase by a direct Lewis acid-catalyzed glycosylation procedure using both the preformed carbohydrate and the heterocyclic base as starting materials. The 5'-hydroxyl, -chloro, -azido, -deoxy, -amino, and -fluoro derivatives were prepared and evaluated in three systems for biological activity relative to adenosine, the true substrate, and 5-iodotubercidin, a known inhibitor. First, each compound was studied kinetically for inhibition of purified human placental adenosine kinase activity. The order of potency was: iodotubercidin > hydroxyl > amino > or = deoxy > fluoro > chloro >> azido. The Ki values for the 5'-hydroxyl and 5'-amino compounds, the two most potent inhibitors, were 80 and 150 nM, respectively. The inhibition appeared to be essentially competitive in nature, although a noncompetitive component of significance for the more potent inhibitors cannot be ruled out. Second, a bioassay was conducted in which the toxicity of 6-methylmercaptopurine riboside toward human CEM lymphoblasts was reversed by varying concentrations of the compounds. The order of effectiveness of the compounds in this system, representing a functional inhibition of adenosine kinase in cultured cells, was about the same as that with the purified enzyme, except that the 5'-chloro and 5'-fluoro compounds were ineffective. Third, the 5'-hydroxyl derivative was evaluated in vivo in a rat pleurisy inflammation model and displayed biological activity at a dose of 30 mg/kg given orally. Finally, the in vitro toxicity of each compound was assessed in CEM lymphoblasts. Results indicated that the two most potent inhibitors in the pyrazolo[3,4-d]pyrimidine ring system, the 5'-hydroxyl (7) and the 5'-amino (20), were 15-fold and 75-fold, respectively, less growth inhibitory than 5-iodotubercidin.

Adenosine Kinase↗
PubMed1993

A stromelysin assay for the assessment of metalloprotease inhibitors on human aggregated proteoglycan.

Human proteoglycan was aggregated to an immobilized hyaluronan solid phase on a 96-well ELISA plate. This complex was then degraded by recombinant human stromelysin. The remaining proteoglycan fragments were detected using a monoclonal antibody probe directed against the chondroitin sulfate (CS) region of the core protein. Stromelysin degraded the aggregate in a time and dose dependent manner as reflected by the loss of the CS epitope. Assay sensitivity was 0.125 U/well with total loss of the CS epitope occurring at 4 U/well. o-phenanthroline (IC50 = 52 microM) and U24522 (IC50 = 9 microM) inhibited degradation, while phosphoramidon did not. Serine and cysteine protease inhibitors had no effect. A comparative analysis of this assay with a reference method, substance P assay, gave similar inhibitor profiles. The use of aggregated human proteoglycan (native conformation) as a substrate, may better reflect how stromelysin inhibitors behave in the presence of complex substrates such as cartilage matrix.

Animals↗
PubMed1993

A comparison of chondrocyte proteoglycan metabolism in monolayer and agarose cultures.

Bovine chondrocyte cultures were established in agarose and in monolayers to compare the effects of cytokines and drugs on matrix metabolism. The production of sulfated glycosaminoglycans (S-GAG) from the medium and cell surface compartments were measured by a dimethylmethylene blue assay. In the agarose cultures most of the proteoglycan remained in the agar, but was continuously released into the medium for more than 50 days. In the monolayers, the cell surface compartment became saturated with S-GAG in 5-6 days. Then a time-dependent decrease of accumulation occurred in the medium after 8-10 days. The anabolic effects of insulin-like growth factor (IGF) and a protein kinase C activator (PMA) were measured in these cultures. IGF and PMA increased S-GAG accumulation in the medium from monolayers but not from agarose cultures. In the agarose cultures, S-GAG was released into the medium after these cultures were changed to serum-free test conditions. This release overshadowed any increase in S-GAG synthesis. The catabolic effect of IL-1 was more evident in the monolayers than in the agarose cultures. Agarose cultures maintain the chondrocyte phenotype longer than monolayers but for initial drug studies monolayer cultures appear to be more appropriate.

Animals↗
PubMed1993

Release of cell surface proteoglycan from chondrocytes by interleukin-1.

A cell culture model was developed to assess factors that can protect cartilage from recombinant human interleukin-1 alpha (IL-1)-induced breakdown. IL-1 (0.01-10 ng/ml) caused a dose-dependent release of cell surface proteoglycan into the medium of bovine and rabbit articular chondrocytes. Sulfated glycosaminoglycan (S-GAG) was detected in the medium and on the cell surface by a dimethlymethylene blue assay. The redistribution of the cell surface S-GAG to the medium compartment required protein synthesis because it was inhibited by cycloheximide and was time-dependent (> 5 h). Although the release was most likely due to de novo synthesis of proteases, standard protease inhibitors failed to prevent the release even when used in combination. TGF-beta and IGF-I increased the amount of S-GAG in both the medium and cell surface compartments, but did not protect from IL-1-induced release. This method has an advantage over a cartilage model of IL-1-induced matrix release because the drug and cytokine exposure time is reduced and the variability is less.

Animals↗
PubMed1993

[Atrial fibrillation: incidence and prognostic factors of embolic risk].

Atrial fibrillation (AF) carries a high risk of systemic embolism, in particular stroke. This is true not only when AF is associated with rheumatic valvular heart disease, but also in the so-called nonvalvular AF (NVAF). The recent randomized clinical trials assessing antithrombotic therapy as primary prevention in NVAF have shown that, untreated, disabling stroke occurs in 2.5%/year, ischemic stroke in 5%/year, stroke and transient ischemic attack in 7%/year, and stroke, transient ischemic attack and silent stroke in > 7%/year. All AF does not carry identical stroke risk. A risk stratification is important in order to decide long-term antithrombotic prophylaxis. A number of important clinical predictors of stroke have been identified. They include age, hypertension, congestive heart failure, previous arterial thromboembolism and previous myocardial infarction. Idiopathic or "lone" AF in patients < 60 years old, without hypertension and diabetes mellitus, carries an extremely low risk of stroke. Also in paroxysmal AF, when patients are < 60 years old and without organic heart disease, the embolic risk is low. The recent onset of AF does not seem to be associated with an excess of embolic risk, in comparison with long-standing AF. In conclusion, the underlying heart disease represents the main determinant of embolic risk. Within the broad spectrum of patients with NVAF a satisfactory risk stratification for thromboembolism can be accomplished by the analysis of clinical risk factors, possibly in association with echocardiographic variables.

Atrial Fibrillation↗
PubMed1993

Immunoradiometric assay of serum myosin as a marker of myocardial cell damage: methodological and clinical evaluation.

We evaluated the performance and analytical parameters of a one-step magnetic IRMA kit for the measurement of myosin in serum. The method uses two monoclonal antibodies selected for their high affinity to the heavy chains of human ventricular myosin. The first antibody is coupled to a magnetic solid phase and the second one is labeled with 125I. The working range of the IRMA (range of myosin concentrations measured with an imprecision < 10% CV) was 250-3600 microU/L and the sensitivity 20.8 +/- 7.2 microU/L. The between-assay variability, evaluated from replicate measurements in different runs of two serum pools was 14.6 CV% for the first pool (259.1 +/- 37.8 microU/L) and 14.3 CV% for the second pool (442.0 +/- 63.1 microU/L), respectively. To evaluate the clinical usefulness of myosin as a marker of myocardial cell damage, serum myosin was measured in patients with acute myocardial infarction (AMI) (n = 9) or subarachnoid hemorrhage (n = 20). The results obtained with the myosin assay were compared with those of two other markers considered specific for myocardial necrosis (CK-MB and myoglobin). In eight patients with AMI, serum myosin was elevated 24-36 hours after the onset of chest pain and reached a maximum at 4-7 days, returning to control levels at 8-11 days. The one remaining AMI patient showed two subsequent peaks in serum CK-MB and myoglobin concentrations (thus suggesting an extension of myocardial necrosis), the myosin concentrations reaching their peak only after 9 days.(ABSTRACT TRUNCATED AT 250 WORDS)

Biomarkers↗
PubMed1992

Frequency and prognostic significance of silent coronary artery disease in patients with cerebral ischemia undergoing carotid endarterectomy.

To evaluate the prevalence and prognostic role of silent coronary artery disease (CAD) in patients with symptomatic high-grade carotid stenosis (70 to 99%) undergoing carotid endarterectomy, and with neither history nor symptoms of CAD, 106 patients (76 men, 30 women, mean age 58.7 years [range 42 to 71]) with recent cerebral ischemia were prospectively studied. Patients were stratified as to the presence (n = 27, 25%) or absence (n = 79, 75%) of silent CAD defined by concordant abnormal exercise electrocardiographic testing and thallium-201 myocardial scintigraphy. The male sex, the severity of the symptomatic carotid lesion (greater than 90%), and the coexistence of contralateral carotid disease identified patients with higher probability of coexisting CAD. The 106 patients underwent 121 operations (bilateral in 15). In the perioperative period, no deaths or cardiac events occurred, 1 patient suffered a recurrent stroke and 3 had a transient ischemic attack. During a mean follow-up period of 5.4 years, 9 patients died (1.7%/year): fatal myocardial infarction occurred in 5 (all in the silent CAD group), cancer in 3 and vertebrobasilar stroke in 1. Nonfatal events occurred in 9 patients: myocardial infarction in 1 (without silent CAD), unstable angina in 3 (with silent CAD), and cerebral ischemic attacks in 5. After 7 years, the Kaplan-Meier estimated survival free from coronary events was 51% in patients with silent CAD, and 98% in patients without CAD (p less than 0.01). In conclusion, among patients with symptomatic high-grade carotid stenosis undergoing carotid endarterectomy, even in absence of history or symptoms of CAD, a silent CAD is detectable in one fourth of the patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Heart-brain interactions in cerebral ischaemia: a non-invasive cardiologic study protocol.

The cardiologic evaluation of patients with cerebral ischaemia should be aimed at: (1) identifying potential cardiac sources for cerebral emboli, (2) detecting a coexisting ischaemic heart disease, even asymptomatic. The present data concerns a ten-year experience of a systematic cardiologic evaluation of patients admitted to the 1st Division of Neurosurgery, Bellaria Hospital, Bologna, Italy, for cerebral ischaemia. A two-dimensional echocardiography was carried out in 344 consecutive patients (mean age 53 years), cardiac abnormalities were observed in 92 (28%) out of the 328 cases with technically adequate examination, embologenic lesions in 57 (17%). In 18 cases the cardiac lesion was unknown before the cerebral event. An exercise ECG testing was carried out in 322 patients (mean age 56 years), resulting in abnormal in 69 out of the 258 with adequate examination (17%). A subsequent exercise 201Tl myocardial scintigraphy confirmed the presence of ischaemic heart disease in 58 cases. Among patients unable to perform an adequate exercise, a dipyridamole 201Tl myocardial scintigraphy was performed in 38 cases showing perfusional defects in 23 (60%), while a dipyridamole echocardiography was performed in 25 cases showing wall motion abnormalities in 9 (36%). A 24-h Holter monitoring was performed in 65 cases: arrhythmias were detected in 27 patients (41%), but a correlation with the cerebral event was suggested only in 3 cases with atrial fibrillation. According to our experience patients with recent ischaemia should be submitted to the following non-invasive cardiologic screening: (1) exercise ECG testing followed, if abnormal or indeterminant, by 201Tl myocardial scintigraphy in all patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Brain Ischemia↗