Showing papers by "University of Milan published in 1985"

A new approach to analysis of the arterial baroreflex.

Abstract: The arterial baroreflex is commonly evaluated by measuring the lengthening and shortening in pulse interval in response to changes in systolic (S) blood pressure (BP) induced by infusion of vasopressor and vasodepressor drugs. This method is simple but has important limitations: only a few observations can be made, reproducibility of the responses is far from optimal, interference by direct drug action on the sinus node and the baroreceptors cannot be excluded and the artificially induced stimuli only poorly mimic the naturally occurring pressor and depressor transients. A new approach was therefore pursued. Blood pressure was recorded intra-arterially for 3 +/- 0.4 h (mean +/- s.d) in 10 unanaesthetized, unrestrained cats and the recording was scanned by a computer to identify the spontaneous sequences of three or more consecutive beats in which SBP progressively rose and pulse interval progressively lengthened (type 1 sequence) or SBP progressively fell and pulse interval progressively shortened (type 2 sequences). Accurate beat-to-beat measurements of SBP and pulse interval were obtained by adopting a very narrow sampling interval of the BP trace, i.e. 1.6 ms real time. For each sequence the regression between the SBP values and the pulse internal values of the following cycle was calculated. In each cat a large number of three-beat sequences were found, the four-, five- and six-beat sequences being, however, progressively less common. All sequences had a high correlation coefficient (r > 0.9), type 1 having a greater slope than type 2 (14.1 +/- 2.5 versus 10.3 +/- 7.6 ms/mmHg, P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Histiocytic syndromes: A review

Abstract: Histiocytoses represent a large, puzzling group of rare skin diseases. The purpose of this review is to schematically outline the clinical, histologic, and ultrastructural features of the most important histiocytic syndromes and to provide the pertinent differential diagnoses. For convenience, we have followed the criterion suggested by Winkelmann, 1 distinguishing these conditions into X and non-X. Among the non-X histiocytoses the self-healing forms have been treated first; the progressive forms follow.

Prognostic Significance of Hyperglycemia in Acute Stroke

Abstract: • Prognostic significance of hyperglycemia on short-term survival was evaluated in 72 patients with acute hemispheric stroke. All patients were admitted within 48 hours of onset, and the neurologic deficit was assessed by means of a standardized score. A computed tomogram was taken in all cases on admission. Mortality was higher in hyperglycemic patients with no history of diabetes mellitus (78%) than in diabetic (45%) and in normoglycemic nondiabetic (29%) patients. In nondiabetic patients, the glucose level correlated with the neurologic score and with lesion size on computed tomogram. Reactive hyperglycemia due to a major stress response accounts for the worse prognosis of these patients. This correlation was not found in diabetic patients. Preexisting hyperglycemia, as well as systemic complications, could explain the higher mortality in these patients compared with normoglycemic nondiabetic patients.

Reliability of urinary creatinine as a parameter used to adjust values of urinary biological indicators.

Abstract: The values of biological indicators used in biological monitoring are usually determined on spot samples of urine. In order to reduce the variations due to dilution, it is common practice to correct the values according to reference parameters, such as urinary creatinine concentration and specific gravity. The aim of the present study was to verify whether creatinine possesses the necessary characteristics for adjustment. The levels of creatinine were not influenced by diuresis, but, contrary to what was expected, the values of the metabolite showed marked intra- and interindividual variations. These data raise serious doubts as to the validity of creatinine as a parameter that can be used for adjustment purposes, and suggest that it would be advisable to ascertain for each biological indicator whether in fact adjustment is of any use. Lastly, since there was only a slight correlation between creatinine levels and specific gravity values, it is concluded that these two parameters cannot be used indifferently for adjustment.

Energy-Level Statistics of Integrable Quantum Systems

Abstract: Using a simple example we show that the distribution for the energy levels for integrable systems is not the uncorrelated Poisson distribution as is commonly believed. In particular, the spectrum was found to be rather rigid. We conjecture that these are typical properties of the integrable quantum systems.

Temporal coincidence between synaptic vesicle fusion and quantal secretion of acetylcholine.

Abstract: We applied the quick-freezing technique to investigate the precise temporal coincidence between the onset of quantal secretion and the appearance of fusions of synaptic vesicles with the prejunctional membrane. Frog cutaneous pectoris nerve-muscle preparations were soaked in modified Ringer's solution with 1 mM 4-aminopyridine, 10 mM Ca2+, and 10(-4) M d-Tubocurarine and quick-frozen 1-10 ms after a single supramaximal shock. The frozen muscles were then either freeze-fractured or cryosubstituted in acetone with 13% OsO4 and processed for thin section electron microscopy. Temporal resolution of less than 1 ms can be achieved using a quick-freeze device that increases the rate of freezing of the muscle after it strikes the chilled copper block (15 degrees K) and that minimizes the precooling of the muscle during its descent toward the block. We minimized variations in transmission time by examining thin sections taken only from the medial edge of the muscle, which was at a fixed distance from the point of stimulation of the nerve. The ultrastructure of the cryosubstituted preparations was well preserved to a depth of 5 - 10 micron, and within this narrow band vesicles were found fused with the axolemma after a minimum delay of 2.5 ms after stimulation of the nerve. Since the total transmission time to this edge of the muscle was approximately 3 ms, these results indicate that the vesicles fuse with the axolemma precisely at the same time the quanta are released. Freeze-fracture does not seem to be an adequate experimental technique for this work because in the well-preserved band of the muscle the fracture plane crosses, but does not cleave, the inner hydrophobic domain of the plasmalemma. Fracture faces may form in deeper regions of the muscle where tissue preservation is unsatisfactory and freezing is delayed.

Finitely additive conditional probabilities

Abstract: This paper includes a concise survey of the work done in order to extend de Finetti's coherence condition to the prevision of conditional random quantities. Sections 1 and 2 deal with the equivalence among different formulations of the extended condition and analyse the relations between it and the usual axiomatic treatment of finitely additive probabilities and previsions. Sections 3 and 4 include some results and remarks about the extensibility of a coherent conditional prevision. Finally, Sections 5 and 6 consider conglomerative previsions in order to frame Kolmogorov's theory of conditional probability and expectation into the more general approach sketched in the previous sections.

Lack of alerting reactions to intermittent cuff inflations during noninvasive blood pressure monitoring

Abstract: Intermittent noninvasive blood pressure monitoring is becoming increasingly popular because of the belief that a daytime blood pressure profile can provide a better clinical evaluation of hypertension than that provided by casual blood pressure measurements. This approach has potential limitations, however, one of which is that the cuff inflations permitting blood pressure to be repeatedly measured may induce an alerting reaction and a pressor response in the patients and lead to an overestimation of their daytime blood pressure. Blood pressure in 22 subjects was invasively recorded for 24 hours by the Oxford method. During the day of the recording blood pressure was also measured by a noninvasive device (Vita-Stat 901), which had its cuff applied to the opposite arm from which the intra-arterial signal was derived. For 2 hours the device provided automatic cuff inflations at 10-minutes intervals. For another 2 hours it was programmed to provide cuff inflations only following patients' commands, also at 10-minute intervals. Analysis of the intra-arterial blood pressure trace during the periods preceding and following the automatically or semiautomatically induced cuff inflations showed that these procedures caused no increment in systolic and diastolic blood pressure. This finding applied not only to the mean data but also to each individual measurement considered separately, including the initial one. Our results indicate that automatic and semiautomatic blood pressure monitorings do not induce an alarm reaction and a blood pressure rise and thus do not overestimate daytime blood pressure values.

Dopamine uptake is differentially regulated in rat striatum and nucleus accumbens.

Abstract: Active uptake of 3,4-dihydroxyphenylethylamine (dopamine) is sodium- and temperature-dependent, strongly inhibited by benztropine and nomifensine, and present in corpus striatum and nucleus accumbens. In rat striatum dopamine uptake is related to a receptor that is specifically labelled by [3H]cocaine in the presence of Na+ and is located on dopaminergic terminals. The dopamine uptake is differentially affected in the two areas by single or repeated injections of cocaine. Cocaine inhibits dopamine uptake in slices of corpus striatum. Moreover Na+-dependent [3H]cocaine binding is not detectable in nucleus accumbens. Nomifensine inhibits [3H]dopamine uptake by interacting with low- and high-affinity sites in corpus striatum, but shows only low affinity for dopamine uptake in nucleus accumbens. The present data indicate that different mechanisms are involved in the regulation of dopamine uptake in corpus striatum and nucleus accumbens.

Cutaneous abnormalities in uremic patients.

Abstract: 94 uremic patients, 68 on regular hemodialysis treatment (RHT) and 26 on chronic ambulatory peritoneal dialysis (CAPD), were followed for up to 20 months in search of dermatological manifestations 79

Non‐linear pH courses with immobilized pH gradients

Abstract: Examples of increased resolution obtained with non-linear pH gradients are presented. Discussed in detail is the “ideal” pH course in the range 4–10, based on the statistical distribution of isoelectric points of protein from data in the literature.

Public attitudes toward epilepsy in Italy: results of a survey and comparison with U.S.A. and West German data.

Abstract: In May 1983, the Italian Institute of Public Opinion DOXA ran, for the Italian League Against Epilepsy, a survey to evaluate public attitudes toward epilepsy in Italy. Eight questions were addressed to a sample of 1,043 adults. Twenty-seven percent did not know what epilepsy was. The least knowledge was observed among elderly people, in the southern regions and the islands, in villages more than in cities, and, in particular, among the poorest social classes. Sixty-one percent had known someone who had epilepsy, and 52% had seen someone having a seizure. When those familiar with epilepsy were asked if they would object to having their children in school or at play associate with persons with seizures, only 11% replied they would object. Seventy percent thought that persons with epilepsy should be employed in jobs like other people, and only 8% thought epilepsy to be a form of insanity. When those familiar with epilepsy were asked if epilepsy is a curable illness, one-third answered negatively, one-third answered affirmatively, and one-third had no personal opinion. The Italian data seem to fall within the standard of the American (1979) and West German (1978) surveys.

The proton pumps of the plasmalemma and the tonoplast of higher plants.

Abstract: Studies on intact cells, membrane vesicles, and reconstituted proteoliposomes have demonstrated in higher plants the existence of an ATP-driven electrogenic proton pump operating at the plasmalemma. There is also evidence of a second ATP-driven H+ pump localized at the tonoplast. The characteristics of both these ATP-driven pumps closely correspond to those of the plasmalemma and tonoplast proton pumps ofNeurospora and yeasts.

Membrane protein analysis by isoelectric focusing in immobilized pH gradients

Abstract: Non-ionic detergents (NP-40, Triton X-100) have poor solubilizing properties on membrane proteins, as demonstrated by separating NP-40-extracted proteins by isoelectric focusing also in the absence of carrier ampholytes (Ampholine), i. e. in immobilized pH gradients (IPG). Addition of 4% Ampholine to the sample and to the IPG gels results in an increase in membrane solubility, from 40% in NP-40 alone to 60% in NP-40 with 4% Ampholine, when both extractions were in the absence of 8 M urea. If the latter solvent is used, these values are increased to 85% for the former and to 100% for the latter extraction conditions. In presence of carrier ampholytes sharp bands are obtained on isoelectric focusing. It is hypothesized that neutral detergents in presence of Ampholine form mixed micelles, mimicking the properties of natural zwitterionic surfactants.

Effects of L-carnitine loading on the aerobic and anaerobic performance of endurance athletes.

Abstract: l-Carnitine (l-c), a well known physiological carrier across the inner mitochondrial membrane of activated long chain fatty acids and acceptor of acyl groups from acyl-CoA, has been recently synthesised industrially. This has made it possible to study the effects ofl-c loading (4 g·d−1 by mouth over a period of 2 weeks) on the aerobic and anaerobic performance of 6 long distance competitive walkers. As a result of the treatment: 1) mean total, free and esterified seruml-c both at rest and shortly after completing a 120 min walk at about 65% of the individual maximal aerobic power\((\dot V_{O_{2\max } } )\) were significantly increased; 2)\(V_{O_{2\max } } \) increased 6%, from 54.5±3.7 (S.D.) to 57.8±47 mlO2·kg−1·min−1 (P<0.02); 3) blood lactate concentration (Lab) as a consequence of short bouts of repeated exercise (series of 10, 15 and 20 jumps off both feet on a force platform) was unchanged; 4) heart rate, pulmonary ventilation, oxygen consumption, and respiratory quotient in the same conditions as for 1) were unchanged. It is concluded that, in trained athletes, as a consequence ofl-c loading\(\dot V_{O_{2\max } } \) is slightly but significantly raised, probably as a result of an activation of substrate flow through the TCA cycle, whereas the lipid contribution to metabolism in prolonged submaximal exercise remains unchanged.

Hypertension in Man with a Kidney Transplant: Role of Familial versus Other Factors

Abstract: Genetic factors are clearly involved in the pathogenesis of essential hypertension in man. In at least three rat models of genetic hypertension it is possible to transplant the hypertension with the k

Mean airway pressure vs. positive end-expiratory pressure during mechanical ventilation.

Abstract: To investigate the effects of both positive end-expiratory pressure (PEEP) and mean airway pressure (Paw) on gas exchange, we used lung lavage to induce severe respiratory insufficiency in six lambs. The animals were then mechanically ventilated at constant tidal volume, respiratory rate, and inspired O2 fraction. PEEP levels were varied -5, +5 and +10 cm H2O around the pressure (Pflex) corresponding to a major change in slope of the inspiratory limb of the respiratory volume-pressure curve. In each animal the effects of the three PEEP levels were studied at two Paw levels, differing by 5 cm H2O. Increasing Paw significantly improved PaO2 and reduced venous admixture. A 5-cm H2O PEEP increase from +5 to +10 did not affect oxygenation; however, oxygenation was significantly better when PEEP was greater than Pflex. Both PaCO2 and anatomic dead space were higher at higher PEEP, and decreased with increasing Paw. Hence, Paw was a major determinant of oxygenation, although a PEEP greater than Pflex appeared necessary to optimize oxygenation at a constant Paw.