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P Paoletti

Publications and source records attributed to P Paoletti.

At least 91 records · Page 5Linked to original sources
PubMed1988

Ventilation-perfusion heterogeneity and gas exchange variables in acute pulmonary embolism evaluated by two different computerized techniques.

The mechanisms by which the disturbances of gas exchange develop in human pulmonary embolism are unknown. We investigated whether the inequality of ventilation-perfusion ratio is associated with the abnormalities of pulmonary gas exchange as evaluated by two different computerized techniques. We measured the alveolar to arterial gradients of oxygen and carbon dioxide by means of a computer based system with a mass spectrometer and the ventilation-perfusion distributions by the multiple inert gas technique in 5 patients with acute pulmonary embolism. In these subjects there was a marked ventilation-perfusion inhomogeneity, as detected from inert gases and this finding was in agreement with the impairment of the alveolar to arterial gradients and of their derived indexes. Consideration on the responsible mechanisms for the disturbances of gas exchange are also reported. In conclusion these two computerized techniques provide a useful assessment of the ventilation-perfusion relationships in order to explain the disturbances of gas exchange in critically ill patients.

Acute Disease↗
PubMed1988

A study on cisternal CSF levels of arachidonic acid metabolites after aneurysmal subarachnoid hemorrhage.

Arachidonic acid (AA) metabolites may play an important role in the pathogenesis of cerebral vasospasm which complicate subarachnoid hemorrhage. Authors have studied levels of 4 major AA metabolites in lumbar CSF samples and in CSF collected from perianeurismatic cisterns of 40 patients admitted with diagnosis of subarachnoid hemorrhage. Lumbar levels of AA metabolites are significantly higher in SAH patients than in control cases; moreover, cisternal CSF levels of PGD2, TxB2 and LTC4 are significantly higher than lumbar levels. Cisternal CSF levels (expressed in pg/ml +/- SEM) are in the "spasm" group: PGD2: 1129.62 +/- 146.33; 6-keto-PGF1 alpha: 214.2 +/- 19.96; TxB2: 4350.25 +/- 656.87; LTC4: 2582.19 +/- 381.83. In the "no spasm" group: PGD2 460.1 +/- 55.89; 6-keto-PGF1 alpha: 306.37 +/- 88.74; TxB2: 5752.5 +/- 899.25; LTC4: 812.92 +/- 142.06. Statistical analysis (paired t-test) shows values significantly higher for cisternal levels of PGD2 (P less than 0.005) and LTC4 (P less than 0.005) in patients presenting vasospasm. This suggests the importance of the subarachnoidal clot as a source of vasoactive compounds. Higher levels of leukotriene C4 in patients presenting vasospasm suggest a role for the compound in the genesis of local inflammatory processes and morphological changes of the arterial wall.

6-Ketoprostaglandin F1 alpha↗
PubMed1988

Cell kinetics of human brain tumors: in vivo study with bromodeoxyuridine and flow cytometry.

Bromodeoxyuridine (BUDR) is a thymidine analog which is incorporated into the DNA of proliferating cells. Since the dose of BUDR needed to label cells is not toxic, cell labelling can be accomplished in vivo, by infusing the substance in patients. A monoclonal antibody against BUDR is then used to identify BUDR-labelled cells. The same cell population can also be stained for DNA content with propidium iodide (PI). Using bivariate flow cytometry (FCM) for measurements, both the percentage of BUDR-labelled cells and their total DNA content can be evaluated. This technique allows one to obtain the labelling index (LI) and the DNA synthesis time (TS). The potential doubling time (Tpot) and the fractional turnover rate (FTR) can be mathematically derived, so that a complete picture of tumor growth can be obtained. Our aim was to ascertain whether this method is clinically applicable and whether the kinetic values obtained are reliable. We studied 22 patients with benign and malignant brain tumors, and observed no immediate toxicity from BUDR administration. The BUDRLI obtained ranged from 0.9% to 3.9% (median: 2.0%) in meningiomas and from 3.8% to 7.6% (median: 6.3%) in malignant gliomas (P less than 0.01). The fraction of S-phase cells determined with the BUDR FCM technique was statistically similar to that found by single DNA flow cytometric analysis performed on duplicate samples of both benign and malignant brain tumors. The TS obtained in malignant gliomas ranged from 10.5 to 227 h (median: 12.8). The calculated Tpot ranged from 7.6 to 26.8 days (median: 11.6), and the calculated FTR ranged from 3.7 to 13.1 cells/100 cells/day (median: 8.8). These data suggest that in vivo BUDR infusion coupled with FCM can be performed in clinical settings, and it is reliable and can easily be used for kinetic studies in clinical trials aimed at evaluating the prognostic relevance of proliferative parameters and in planning tumor treatment.

Adult↗
PubMed1988

Objective radiographic criteria to differentiate cardiac, renal, and injury lung edema.

To assess the value of the chest radiograph in differentiating various types of pulmonary edema, we retrospectively analyzed 119 films of patients with pulmonary edema caused by left heart decompensation (group 1;N = 56), renal failure (group 2; N = 19), and lung microvascular injury (group 3; N = 44). Chest radiographs were examined independently by two trained observers, unaware of the clinical diagnosis, according to a standardized reading table. The two observers assigned chest films to the corresponding group with an accuracy of 86% and 90%, respectively. To test the observers' objectivity, we used radiographic findings as input variables for discriminant analysis. Computer-generated numerical functions identified pulmonary edema etiology with an accuracy of 88% when considering the three groups together. When groups were compared as pairs, percentages of correct classification were 91% (group 1 vs. group 2), 93% (group 1 vs. group 3), and 100% (group 2 vs. group 3). Thus, a standardized reading of chest radiographs may be considered a reliable clinical method for identifying pulmonary edema etiology.

Heart Failure↗
PubMed1988

Bioenergetics of different brain areas after experimental subarachnoid hemorrhage in rats.

We studied energy metabolism after experimental subarachnoid hemorrhage in rats. Four different cerebral areas were tested: frontal cortex, occipital cortex, hippocampus, and brainstem. Vmax of the following enzymatic activities was evaluated: in the homogenate: hexokinase, phosphofructokinase, and lactate dehydrogenase for the glycolytic pathway, and glucose-6-phosphate dehydrogenase for the hexose monophosphate shunt; in the purified nonsynaptic mitochondria: NAD+-isocitrate dehydrogenase, citrate synthase, and succinate dehydrogenase for the Krebs cycle, and cytochrome oxidase for the electron transfer chain. We also evaluated some parameters related to the respiration of nonsynaptic mitochondria (State 3, State 4, uncoupled state, respiratory control ratio, and ADP:O ratio). Subarachnoid hemorrhage did not significantly affect Vmax of the enzymatic activities related to anaerobic and aerobic metabolism; however, mitochondrial respiration was affected, particularly in the presence of NADH-producing substrates (glutamate + malate).

Adenosine Diphosphate↗
PubMed1988

Single breath nitrogen test in an epidemiologic survey in North Italy. Reliability, reference values and relationships with symptoms.

The usefulness of single breath nitrogen test (SBN2) was evaluated in a cross-sectional epidemiologic survey on a general population sample (n = 3,289) of North Italy. Each subject was submitted to CNR standardized questionnaire and to lung function testing using automated equipment (Hewlett-Packard 47804S). Acceptable closing volume (CV) and slope of alveolar plateau (DN2%/L) tracings were performed by only 1,370 and 1,982 subjects respectively, in comparison with the 2,638 diffusing capacity and the 3,079 forced vital capacity acceptable maneuvers. Prediction equations were computed on normal subjects for CV indices, with the exception of DN2%/L: they were similar to those found in other studies. Significant differences among smoking categories were found for all the SBN2 parameters in males, but only for DN2%/L in females. The latter was also able to distinguish either subjects with airway obstruction from those without it or symptomatic from asymptomatic individuals, but DN2%/L did not give more information than Vmax75, a sensitive index of flow volume curve. Our results suggest that the place of SBN2 in large scale epidemiologic testing has not been justified.

Adolescent↗
PubMed1988

CSF leukotriene C4 following subarachnoid hemorrhage.

Leukotrienes derive from arachidonic acid metabolism via the lipoxygenase pathway and modulate several cellular events. In the central nervous system, leukotrienes are mainly synthesized in the gray matter and in vascular tissues. Their production is enhanced in ischemic conditions and in experimental subarachnoid hemorrhage (SAH). Previous studies have indicated the ability of the leukotrienes C4 and D4 to constrict arterial vessels in vivo and in vitro and have suggested their involvement in the pathogenesis of cerebral arterial spasm. In the present study, the authors measured lumbar and cisternal cerebrospinal fluid (CSF) levels of leukotriene C4 in 48 patients who had suffered aneurysmal SAH. In 12 of the cases, symptomatic and radiological spasm was evident. The mean lumbar CSF level of immunoreactive-like activity of leukotriene C4 (i-LTC4) was significantly higher (p less than 0.005) than in control cases, while the cisternal CSF level was higher than the lumbar mean concentration (p less than 0.005). Patients presenting with vasospasm had significantly higher levels of i-LTC4 compared to patients without symptomatic vasospasm. This is the first report concerning monitoring of i-LTC4 levels in the CSF after SAH. The results of this study suggest that: 1) metabolism of arachidonic acid via the lipoxygenase pathway is enhanced after SAH; 2) the higher cisternal CSF levels of i-LTC4 may be part of the biological response in the perianeurysmal subarachnoid cisterns after the hemorrhage; and 3) the higher CSF levels of i-LTC4 in patients presenting with vasospasm suggest that a relationship exists between this compound and arterial spasm and/or reflect the development of cerebral ischemic damage.

Cisterna Magna↗
PubMed1988

Prevalence of respiratory symptoms in an unpolluted area of northern Italy.

Using a multistage stratified geographic cluster sample of households living in an unpolluted area of Northern Italy (near Venice), we enrolled 3289 inhabitants (aged 8-64 yr) for a longitudinal respiratory study. During the first cross-sectional survey, before the start of operation of a large oil-burning thermoelectric power plant, they completed a standardized administered questionnaire and performed several lung function tests. In the whole sample, dyspnoea grade 1 (11%), chronic cough and chronic phlegm (9%) were the most frequent respiratory symptoms; all the symptoms except dyspnoea were more prevalent in males than in females. Smokers (S) showed higher prevalence rates than ex-smokers (ES) and nonsmokers (NS), especially in males. In both sexes, the frequency of respiratory symptoms increased with increasing smoking as assessed by pack-years. An inverse relationship between prevalence of symptoms and socio-economic status was also observed. All tests of lung function were significantly impaired in S compared with NS in males; single-breath CO diffusing capacity and slope of alveolar plateau but not spirometric indices were significantly impaired in female S compared to female ES and NS. Finally, our prevalence rates were lower than in other epidemiological surveys: this result may be ascribed to the low levels of air pollution measured in the area.

Age Factors↗
PubMed1988

Plasma-exchange in myasthenia gravis: a study in 20 patients.

Twenty patients with myasthenia gravis (MG) of generalized 2A and 2B types according to the Ossermann classification were treated with a course of nine plasma exchanges (PE) every two days. Before starting of the course, at the fourth exchange, and at the end of the course, the muscle balance was assessed following a special protocol. Other functions, such as respiratory function, stapedial reflex, phonation, and electro-oculographic activity were assessed and a Desmedt test was done. Three patients showed complete remission of symptoms, 8 showed good improvement and 6 mild improvement. Three showed no improvement. In total 85% of patients gained from PE. The onset of improvement was rapid in all patients but in some it lasted only a short time while in others it persisted for several weeks and even months, without the need for immunosuppressive therapy.

Adult↗
PubMed1987

Respiratory effects of non-tobacco cigarettes.

Data from the Tucson epidemiological study of airways obstructive disease on smoking of non-tobacco cigarettes such as marijuana were analysed to determine the effect of such smoking on respiratory symptoms and pulmonary function. Among adults aged under 40, 14% had smoked non-tobacco cigarettes at some time and 9% were current users. The prevalence of respiratory symptoms was increased in smokers of non-tobacco cigarettes. After tobacco smoking had been controlled for men who smoked non-tobacco cigarettes showed significant decreases in expiratory flow rates at low lung volumes and in the ratio of the forced expiratory volume in one second to the vital capacity. This effect on pulmonary function in male non-tobacco cigarette smokers was greater than the effect of tobacco cigarette smoking. These data suggest that non-tobacco cigarette smoking may be an important risk factor in young adults with respiratory symptoms or evidence of airways obstruction.

Adolescent↗
PubMed1987

Arachidonic acid metabolic profiles in human meningiomas and gliomas.

We determined arachidonic acid (AA) cyclooxygenase metabolic profiles in specimens of human intracranial tumors (gliomas and meningiomas) and, when available, normal brain tissue. Samples were collected at surgery and immediately frozen in liquid nitrogen. The five stable metabolites of AA (PGE2, PGD2, PGF2 alpha, 6-keto-PGF1 alpha and TXB2) were measured by high-resolution gas chromatography-mass spectrometry after ex vivo metabolism of endogenous AA by tissue homogenates. The absolute amounts of AA metabolites varied widely between samples, though meningiomas and gliomas showed characteristic profiles. Compared to the slow-growing benign meningiomas, the rapidly-growing infiltrating gliomas had higher synthesis of TXA2 (reported as a procancer metabolite) and lower synthesis of PGD2 and PGI2 (reported as anticancer metabolites). A higher overall synthesis capacity, preferentially toward TXA2, was found in glioblastomas than in non-pathological brain tissue.

Arachidonic Acid↗
PubMed1987

Cisternal and lumbar CSF levels of arachidonate metabolites after subarachnoid haemorrhage: an assessment of the biochemical hypothesis of vasospasm.

Several naturally occurring compounds have been identified in human cerebrospinal fluid (CSF) after subarachnoid haemorrhage (SAH) as possible vasoactive agents involved in the biochemical mechanism of vasospasm. The authors have measured, in 30 patients admitted for SAH, CSF concentrations of two arachidonic acid metabolites. Prostacyclin and Prostaglandin D2, as representative of vasodilator and vasoconstrictor compounds. CSF samples were made available by lumbar punctures and intraoperative cisternal punctures. Nine patients presented with symptomatic vasospasm: lumbar CSF Prostaglandin D2 levels are significantly higher than in patients without vasospasm. The Cisternal Prostaglandin D2 level is significantly higher than the lumbar CSF concentration; CSF Prostacyclin levels do not significantly differ in the two groups of patients. These data suggest the presence of an imbalanced biochemical situation responsible for promoting vasospasm. The evaluation of cisternal levels of arachidonate metabolites support the hypothesis of the clotting phenomenon around the ruptured aneurysm wall as an important predictive pattern of vasospasm onset after SAH, as shown in computed tomography.

6-Ketoprostaglandin F1 alpha↗
PubMed1987

Comparison of algorithms for determining the end-point of the forced vital capacity maneuver.

The criteria of the American Thoracic Society (ATS) for determining the end-point of the forced vital capacity (FVC) maneuver were compared with an algorithm employed by a computer system (Hewlett-Packard), which yields a later end-point. The 150 subjects tested were divided into five groups of 30 on the basis of the following spirometric diagnoses: normal; small airways' obstruction (SAO); mild airways' obstruction (MAO); severe chronic obstructive pulmonary disease (COPD); or restrictive disease. The subjects performed a minimum of three maneuvers according to ATS standards, and the flow-volume curves with the greatest sum of FVC and forced expiratory volume in one second (FEV) were chosen for analysis by the two algorithms. Hewlett-Packard (HP) values for FVC and FVC time were always higher than the corresponding ATS values, and the HP values for flows were always lower than the corresponding ATS values. The higher differences were observed in the SAO group. In the group with severe COPD, high FVC differences and low flow differences were observed; on the contrary, in the restrictive group, low FVC differences and high flow differences were present. These results, in addition to the different location of the FVC end point, may be explained by the different morphology of the flow-volume curves. In conclusion, the ATS algorithm caused a systematic underevaluation of FVC and a systematic overevaluation of flows, which cause practical consequences only in the SAO group. In fact, 28 percent (17/60) of the subjects with SAO characteristics were considered "normal" using ATS criteria for the end-point.

Adult↗
PubMed1987

Plasma-exchange in idiopathic radiculopolyneuropathies: a study in 62 patients.

The effectiveness of plasma exchange (PE) in the treatment of acute and chronic idiopathic radioculopolyneuropathies (IR) is discussed on the basis of the literature and personal data. Results of controlled trials by Swedish, French and North American groups are favourable to the use of PE in acute forms, whereas one English group found no significant differences between treated patients and controls. Dick et al. (1986) reported significant improvement also in patients with chronic forms after PE. Personal data from a non-controlled series of 62 acute and chronic IR and from a trial group of 12 acute patients and 12 controls indicated that PE--though helpful in Guillain-Barré syndrome--was not so useful in chronic forms.

Chronic Disease↗