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Biomedical subjects

M Rossi

Publications and source records attributed to M Rossi.

At least 505 records · Page 28Linked to original sources
PubMed1990

Use of the magnitude estimation technique for assessing the performance of text-to-speech synthesis systems.

As text-to-speech systems develop, it becomes necessary to compare various solutions and to evaluate whether a change in the synthesis procedure has an effect on the listener's attitude to the system. The possibility of directly scaling intelligibility, naturalness, and user's satisfaction (i.e., acceptability) with the magnitude estimation technique is investigated. A magnitude estimation protocol suitable for this purpose is described. In general, within the limits of the methodological constraints discussed in this paper, the procedure appears to be reliable and valid for quantifying the perceived attributes of synthesized speech.

Communication Devices for People with Disabilities↗
PubMed1990

Liver enzyme abnormalities in subacute thyroiditis.

In a retrospective study of liver function tests in subacute thyroiditis, 13 out of 22 patients with the disease demonstrated an elevation of alkaline phosphatase level. Less prevalent abnormalities were elevations in gamma-glutamyl transpeptidase (5 pts), alanine (4 pts) and aspartate (3 pts) aminotransferase activities. These enzyme alterations were not correlated with thyroid hormone levels, concomitant diseases, drugs or alcoholic intake, and normalized in six patients followed until recovery. A benign, short-lived and subclinical hepatic involvement is common in subacute thyroiditis.

Acute Disease↗
PubMed1990

The effect of membrane lipid molecular species on rat brain base-exchange reactions: an appraisal of phosphatidylserine and of polyunsaturated phosphatidylcholine.

Rat brain microsomal membranes were solubilized with octyl glucoside and reassembled by removing the detergent. The composition of reconstituted membranes was modified by adding exogenous lipid to the detergent-membrane mixtures. The base-exchange reactions were sensitive to these procedures. The inhibiting or activating capacity of added lipid was related to the charge of polar head groups; indeed, the addition of phosphatidylserine always resulted in inhibition and that of phosphatidylcholine very often in activation. The addition of phospholipid possessing unsaturated acyl chains inhibited less (or activated more) serine and choline base-exchange than the addition of saturated species. It is concluded that phosphatidylserine and polyunsaturated phosphatidylcholine have opposite effects on base-exchange.

Animals↗
PubMed1990

[Carcinoid tumor of the appendix].

The Authors report a case of tumour carcinoid of the appendix incidentally found at operation for appendicitis in a young patient. Diagnosis was confirmed at histologic analysis of the operating piece. Appendiceal carcinoid is the most frequent carcinoid tumor of the gastrointestinal tract and rarely becomes malignant. The Authors emphasize the importance of the knowledge of this not rare neoplasm.

Adult↗
PubMed1990

[The nuclear magnetic resonance in endocrinology. Spectroscopy and imaging, present and future].

The first part, after a brief historical reminder, gives an oversimplified and non-rigorous approach to the Nuclear Magnetic Resonance (NMR) phenomenon; this "physical" introduction leads the clinician to know the essential about the spectral and imaging techniques in NMR, just to understand what is done... The second part of this paper shows some medical applications of these two aspects of NMR, with help of some examples, taken from the literature, according to what is concerned with endocrinology. Pure bio chemical applications (enzymology), or those concerning isolated (and perfused) organs, or living animals, and even human beings, are numerous and complementary, and there is no doubt that the applications of NMR technologies to medicine will know a promising future...

Animals↗
PubMed1990

[Biphotonic absorptiometry of the foot: methodology and application to algodystrophy].

A simple methodology for the evaluation of the bone mineral content of the foot by biphotonic absorptiometry is described. From the study of a test population, a pathological demineralization threshold of 10%, given that the measurement is expressed in g, has been defined at the level of the forepart of the tarsus. This threshold enables the significant distinction between the test population and a population with algodystrophy. Biphotonic absorptiometry seems to provide a quantitative diagnostic argument to complement the radiographical and scintigraphical examinations.

Absorptiometry, Photon↗
PubMed1990

[Double filtration plasmapheresis in the treatment of vascular complications of hyperlipidemia].

Double-filtration plasmapheresis is a therapeutic procedure for the extracorporeal depuration of atherogenic lipoproteins, which does not require the administration to the patient of exogenous fluids. We have used it in two patients affected by hyperlipidemia with severe cardiovascular complications. Both patients presented a dramatic improvement of their symptoms (angina pectoris and claudicatio intermittens) shortly after the beginning of treatment. By the brisk reduction of circulating low-density lipoproteins, plasma-filtration may favor the removal of cholesterol from atheromatous plaques of vessel walls. Furthermore, this procedure may modify platelet aggregation and blood viscosity. Our observation suggests that plasma-filtration may be useful not only for delaying coronary heart disease in the rare cases of homozygous familial hypercholesterolemia, but also in the management of patients with other primary hyperlipoproteinemias and clinical manifestations of already established cardiovascular complications.

Adult↗
PubMed1989

Stability and activity of a thermostable malic enzyme in denaturants and water-miscible organic solvents.

A study was made of the effects of common protein denaturants and water-miscible organic solvents on both the stability and activity of the malic enzyme [(S)-malate:NADP+ oxidoreductase (oxaloacetate-decarboxylating); EC 1.1.1.40] from the extreme thermoacidophilic archaebacterium Sulfolobus solfataricus. At 25 degrees C, the enzyme was not inactivated in 4 M urea or 0.05% SDS over 24 h, while the half-life was 30 min in 6 M guanidine hydrochloride and 5 h in 0.075% SDS. The enzyme stability in water-miscible organic solvents at 25 degrees C is somewhat surprising: after a 24-h incubation, the enzyme was completely active in 50% dimethylformamide; it lost 15% of its initial activity in 50% methanol or 15% ethanol. However, the resistance to organic solvents was greatly reduced at higher temperatures. The enzyme was able to catalyze the malate conversion even in the presence of 1.5% Triton X-100 or sodium deoxycholate. A number of solvents were found to stimulate the malic activity independent of time. Studies with 50% methanol revealed that the activation was reversible and inversely related to the temperature; moreover, the solvent was demonstrated to exclusively affect the maximal velocity of catalysis, the Km values for both substrates being unchanged. Investigation was made to find out whether there was a correlation between enzyme stability, as well as activation, and hydrophobicity of the organic medium. The residual malic activity after incubation in the water/organic medium correlated inversely with the logarithm of the partition coefficient in octanol/H2O of the mixture used as a hydrophobicity index. On the other hand, the extent of activation depended directly on the logarithm of the molar concentration of the organic solvent required for maximal enzymatic activation. Because of its remarkable resistance to organic solvents required for maximal enzymatic activation. Because of its remarkable resistance to organic solvents and protein denaturants in general, the malic enzyme from Sulfolobus solfataricus can be considered suitable for biotechnological applications.

Archaea↗
PubMed1989

Conformation and ion binding properties of peptides related to calcium binding domain III of bovine brain calmodulin.

The conformational and ion binding properties of the sequences 93-104, 96-104, and 93-98 of domain III of bovine brain calmodulin (CaM) have been studied by CD and Tb3+-mediated fluorescence. In aqueous solution the interaction of all fragments with Ca2+ and Mg2+ ions is very weak and without any effect on the peptide conformation, which remains always random. In trifluoroethanol the interaction is very strong and the different fragments exhibit very distinct binding properties. In particular, the dodecapeptide fragment 93-104, and its N-terminal hexapeptide 98-104, bind calcium and magnesium with a very high binding constant (Kb greater than 10(5) M-1), undergoing a substantial conformational change. The structural rearrangement is particularly evident in the hexapeptide fragment, which tend to form a beta-bend. The C-terminal nonapeptide fragment 96-104 interacts with calcium and magnesium more weakly, and the binding process causes a decrease of ordered structure. These results suggest that, even in the entire dodecapeptide sequence corresponding to the loop of domain III of CaM, the calcium binding site is shifted toward the N-terminal hexapeptide segment. This interpretation is consistent with the results of crystallographic studies of CaM, which show that the calcium ions are located toward the amino terminal portion of the loop.

Amino Acid Sequence↗
PubMed1989

Effects of imipramine on the autonomic responses of obsessive-compulsives to auditory tones.

It has been argued that a mechanism of clomipramine's efficacy for obsessive-compulsive disorder is its reduction of excessive autonomic reactivity. The present study evaluated this proposed mechanism of action by assessing the effect on autonomic responding of imipramine, which is structurally similar to clomipramine, but lacks therapeutic efficacy for obsessive-compulsives. Twenty-three obsessive-compulsive patients received three sessions of 20 unsignalled 1000-Hz, 100-dB tones of 1-sec duration and 100-msec rise-time. Skin conductance level, response frequency and magnitude, and heart rate were scored for an adaptation period and for each tone onset. Six weeks after the first tone session, during which half of the subjects received imipramine while the remainder received placebo, the second tone assessment was performed. A third tone assessment was performed after an additional 4 weeks of medication. Percentage of nonresponders was also evaluated for each group. Imipramine reduced electrodermal activity and increased heart rate. Skin conductance level and both number and amplitude of responses decreased significantly after 6 weeks of imipramine, compared with placebo, with further attenuation of electrodermal activity after 10 weeks of the drug. Electrodermal nonresponding increased dramatically for the imipramine group as compared to the nondrug group. These results reveal effects of imipramine on autonomic responding, and cast doubt on the hypothesis that a mechanism for successful drug treatment of obsessive-compulsive disorder is decreased autonomic reactivity.

Acoustic Stimulation↗
PubMed1989

Relationship between phasic changes in human skin blood flow and autonomic tone.

Heart rate beat-to-beat oscillations synchronous with respiration and blood pressure waves, have been found to be a marker of sympathovagal interaction in man and animals. Oscillations of heart rate, respiration, and cutaneous blood flow were simultaneously recorded to assess the relationship between autonomic nervous control and cutaneous circulation in a group of 21 healthy subjects and in a group of 6 healthy patients after brachial plexus anesthesia and consequent sympathetic blockade. In the first group, changes in posture were employed to modify autonomic tone. Relative changes in cutaneous blood flow were recorded by laser-Doppler flowmetry. Spectral analysis techniques (cross-correlation) were used to quantify the relationship between oscillations common to the recorded signals. A standing maneuver induced a significant decrease of the cross-correlation between respiratory and heart rate fluctuations (from 4.93 +/- 0.16 to 4.44 +/- 0.16 a.u.; P less than 0.001), and a significant increase of the cross-correlation between heart rate and skin blood flow fluctuations (from 0.64 +/- 0.31 to 1.33 +/- 0.21 a.u.; P less than 0.001), but did not modify the cross-correlation between respiratory and skin blood flow fluctuations (from 2.87 +/- 0.15 to 3.04 +/- 0.14 a.u.; NS). After the standing maneuver the maximum correlation between heart rate and skin blood flow was always due to oscillations in the range of 0.1 Hz (or 10-sec period), similar to the oscillations described in large arteries. Sympathetic blockade reduced significantly the cross-correlation between heart rate and skin blood flow (P less than 0.001). These results suggest that the cross-correlation between skin blood flow and heart rate at 10-sec period fluctuations can be used as an index of the influence of the autonomic tone on skin blood circulation.

Adolescent↗
PubMed1989

5-Aza-2'-deoxycytidine as inducer of differentiation and growth inhibition in mouse neuroblastoma cells.

We studied the effect of 5-aza-2'-deoxycytidine (5-AZA-CdR) on the differentiation of murine 41A3 neuroblastoma cells. Neuroblastoma cells treated with 0.1-1.0 microM 5-AZA-CdR underwent differentiation; markers of neuronal functions, such as acetylcholinesterase activity and growth of nerve fibers, were expressed at a higher level in the drug-treated cells than in the controls. This increased expression was accompanied by significant hypomethylation of newly synthesized DNA. A secondary event seemed to be a partial inhibition of DNA synthesis, cell proliferation and colony-forming activity. These effects were more pronounced than those caused by the related cytidine analog, 1-beta-D-arabinosil-cytosine (ARA-C). The results obtained suggest that 5-AZA-CdR may be an effective agent for the growth control of human neuroblastoma cells.

Acetylcholinesterase↗
PubMed1989

Cardiac autonomic dysfunction in obese subjects.

1. The prevalence of cardiac autonomic alterations was evaluated in 23 obese subjects with body mass index 37.2 +/- 3.03 kg/m2 (mean +/- SD), compared with 78 controls with body mass index 22.5 +/- 2.6 kg/m2 (P less than 0.001). 2. Cardiac autonomic function was assessed by four standard tests (heart rate response to deep breathing and to the Valsalva manoeuvre, systolic blood pressure fall after standing and diastolic pressure rise during handgrip) and by the cross-correlation test, a new method of computerized analysis of respiratory sinus arrhythmia based on spectral analysis of electrocardiographic and respiratory signal. 3. Considering tests indicative of parasympathetic function, only the heart rate response to the deep breathing and the cross-correlation test were significantly lower in the obese than in the control group [deep breathing = 13.95 +/- 8.65 beats/min (mean +/- SD) vs 24.5 +/- 7.65, P less than 0.001; cross-correlation 4.28 +/- 0.74 units vs 5.14 +/- 0.63, P less than 0.001]. Deep breathing and/or cross-correlation were abnormal in 10 (43.5%) obese subjects (deep breathing: seven subjects, cross-correlation: eight subjects). No significant difference between groups was found for the response to the Valsalva manoeuvre: the Valsalva ratio was 1.69 +/- 0.45 in obese subjects and 1.88 +/- 0.33 in controls (P = NS). The Valsalva ratio was abnormal in three obese subjects. 4. No significant differences were found between groups for tests indicative of sympathetic function.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗