Biomedical subjects

C Lamberti

Publications and source records attributed to C Lamberti.

At least 73 records · Page 4Linked to original sources

PubMed1996

Evaluation of differential optical flow techniques on synthesized echo images.

The performance of three methods for evaluation of motion on synthesized 2-D echo image sequences with features similar to real ones are examined. The selected techniques based on the computation of optical flow are of the differential type and assume that the image brightness pattern is constant over time. They differ in the choice of the smoothing term and in the local or global treatment of the domain. The images were synthesized by simulating the process of echo formation, considering the interaction between ultrasonic fields and human tissues. Moreover, two different approaches were followed to generate the sequences: 1) a known motion field was applied to the intensity distribution of the synthesized images; 2) a known motion field was applied directly to the point scatterer distribution of the tissue. Favorable results were obtained by applying Lucas-Kanade and Horn-Schunck techniques to the sequences of the first type, while all the techniques produced large errors when applied to the other type of sequences. A discussion about the suitability of the above-mentioned techniques for evaluation of motion on real echocardiographic images is also presented together with some results.

Algorithms↗

PubMed1994

Role of histamine in rodent antinociception.

1. Effects of substances which are able to alter brain histamine levels on the nociceptive threshold were investigated in mice and rats by means of tests inducing three different kinds of noxious stimuli: mechanical (paw pressure), chemical (abdominal constriction) and thermal (hot plate). 2. A wide range of i.c.v. doses of histamine 2HCl was studied. Relatively high dose were dose-dependently antinociceptive in all three tests: 5-100 micrograms per rat in the paw pressure test, 5-50 micrograms per mouse in the abdominal constriction test and 50-100 micrograms per mouse in the hot plate test. Conversely, very low doses were hyperalgesic: 0.5 microgram per rat in the paw pressure test and 0.1-1 microgram per mouse in the hot plate test. In the abdominal constriction test no hyperalgesic effect was observed. 3. The histamine H3 antagonist, thioperamide maleate, elicited a weak but statistically significant dose-dependent antinociceptive effect by both parenteral (10-40 mg kg-1) and i.c.v. (1.1-10 micrograms per rat and 3.4-10 micrograms per mouse) routes. 4. The histamine H3 agonist, (R)-alpha-methylhistamine dihydrogenomaleate was hyperalgesic, with a rapid effect (15 min after treatment) following i.c.v. administration of 1 microgram per rat and 3 microgram per mouse, or i.p. administration of 100 mg kg-1 in mice. In rats 20 mg kg-1, i.p. elicited hyperalgesia only 4 h after treatment. 5. Thioperamide-induced antinociception was completely prevented by pretreatment with a non-hyperalgesic i.p. dose of (R)-alpha-methylhistamine in the mouse hot plate and abdominal constriction tests. Antagonism was also observed when both substances were administered i.c.v. in rats. 6. L-Histidine HCl dose-dependently induced a slowly occurring antinociception in all three tests. The doses of 250 and 500 mg kg-1, i.p. were effective in the rat paw pressure test, and those of 500 and 1500 mg kg-1, i.p. in the mouse hot plate test. In the mouse abdominal constriction test 500 and 1000 mg kg-1, i.p. showed their maximum effect 2 h after treatment. 7. The histamine N-methyltransferase inhibitor, metoprine, elicited a long-lasting, dose-dependent antinociception in all three tests by both i.p. (10-30 mg kg-1) and i.c.v. (50-100 micrograms per rat) routes. 8. To ascertain the mechanism of action of the antinociceptive effect of L-histidine and metoprine, the two substances were also studied in combination with the histamine synthesis inhibitor (S)-alpha-fluoromethylhistidine and with (R)-alpha-methylhistamine, respectively. L-Histidine antinociception was completely antagonized in all three tests by pretreatment with (S)-alpha-fluoromethylhistidine HCl (50 mg kg-1, i.p.)administered 2 h before L-histidine treatment. Similarly, metoprine antinociception was prevented by(R)-alpha-methylhistamine dihydrogenomaleate 20 mg kg-1, i.p. administered 15 min before metoprine. Both(S)-alpha-fluoromethylhistidine and (R)-alpha-methylhistamine were used at doses which did not modify the nociceptive threshold when given alone.9. The catabolism product, 1-methylhistamine, administered i.c.v. had no effect in either rat paw pressure or mouse abdominal constriction tests.10. These results indicate that the antinociceptive action of histamine may take place on the postsynaptic site, and that its hyperalgesic effect occurs with low doses acting on the presynaptic receptor. This hypothesis is supported by the fact that the H3 antagonist, thioperamide is antinociceptive and the H3 agonist, (R)-alpha-methylhistamine is hyperalgesic, probably modulating endogenous histamine release.L-Histidine and metoprine, which are both able to increase brain histamine levels, are also able to induce antinociception in mice and rats. Involvement of the histaminergic system in the modulation of nociceptive stimuli is thus proposed.

Analgesics↗

PubMed1994

Comparative evaluation of different methods to estimate urea distribution volume and generation rate.

Eight methods to estimate urea distribution volume and generation rate from blood urea samples measured in dialysis patients are reviewed. An analytical solution has been provided for a double-pool variable volume kinetic model to allow for faster and more accurate simulation and identification. The reliable parameter estimates provided by the double-pool kinetic model starting from seven samples, were assumed as references for the estimates obtained by the remaining methods. These include three kinetic models and four methods based on urea mass-balance. In particular, the estimation techniques differ in the number of compartments where urea is assumed distributed (double- and single-pool) or in the number of blood urea samples. Among the methods based on mass-balance, two techniques neglecting the weight loss or the urea generation during dialysis, were also analysed. The results obtained during hemofiltration sessions using three samples, usually available in clinical practice at the beginning and at the end of dialysis, demonstrate that a new method based on double-pool kinetics provides, on average, the most reliable estimates. Moreover, methods belonging to a single pool view and including both weight loss and urea generation during dialysis seem to underestimate by 1 divided by 2 liters the urea distribution volume. However, neglecting the weight loss or the urea generation can overcompensate this error, resulting in a significant overestimation of the distribution volume. Finally, it has been experimentally proved that the single-pool kinetic methods overestimate the urea production rate, while techniques based on mass balance provide more reliable values.

Adult↗

PubMed1994

ELISA method for evaluation of anti-A60 IgG in patients with pulmonary and extrapulmonary tuberculosis.

Several studies on the IgG mediated humoral immune response against the mycobacterial antigen A60 are available in the literature. However extensive variability in observed responses has been reported. In the present study we measured by ELISA the titers of IgG antibodies against A60 in 50 tuberculin negative healthy subjects, (Group I); 44 tuberculin positive healthy subjects, (Group II); 13 patients with healed Tuberculosis (Group III); 22 patients with a defined acute or chronic Non Tuberculous Pulmonary Pathology (Group IV); 42 patients suffering from sputum positive Active Pulmonary Tuberculosis, (Group V); 15 patients with sputum negative Active Pulmonary Tuberculosis (Group VI) and 16 patients with Active Extrapulmonary Tuberculosis (Group VII). The assay was performed at the time of recruitment into the study, corresponding for patients of Groups IV to VII to the day of hospital admission; in patients from Groups III to VII the assay was repeated two weeks later. The cut-off point was defined as mean +2SD of values found in Groups I-IV and was 0.372 (expressed in Optical Density). By using this cut-off, the test on first blood samples was positive in 1/50 subjects from Group I, 1/44 from Group II, 0/13 from Group III, 3/22 patients from Group IV, 35/42 from Group V, 9/15 from Group VI, 9/16 from Group VII. On second blood samples, kept 9-12 days after starting anti-TB chemotherapy in Groups V, VI and VII, the test resulted positive in 0/13 patients from Group III, 3/22 from Group IV, 39/42 from Group V, 13/15 from Group VI and 14/16 from Group VII.

Adolescent↗

PubMed1993

Circadian activity, nociceptive thresholds, nigrostriatal and mesolimbic dopaminergic activity in the Naples High- and Low-Excitability rat lines.

These experiments were designed to further characterize the differential phenotypic constellation of the Naples High- (NHE) and Naples Low-Excitability (NLE) lines. In order to determine possible differences between NHE and NLE rats in activity and circadian rhythms, besides reactivity to novelty (selection trait), adult male rats of both strains were tested during two 10-min exposures to a Làt-maze. They were then kept in activity cages continuously for 3 days. Moreover, nociceptive thresholds were measured with the hot-plate and the tail-flick test, to probe the possibility that these rats could be differentially sensitive to nociceptive stimuli. Further, the integrity of the nigro-striatal and mesolimbic system was investigated by measuring tyrosine-hydroxylase activity in the striatum and 3,4-dihydroxyphenylacetic acid (DOPAC) levels in the striatum as well as in the nucleus accumbens. In addition, TH activity was measured in the adrenals to probe the sympathetic section of the neurovegetative system. The results indicate that NHE and NLE rats differ by a factor of two in their phasic activity in a Làt-maze. In contrast, no differences in 24-h activity during the dark or light phase could be observed in the activity cages. However, NHE rats anticipated the light-on stimulus in the morning by reducing their activity 1 h earlier than NLE rats. Further, no difference could be found with the hot-plate and the tail-flick test. Finally, biochemical analyses revealed no difference in the NHE and NLE rats in the main terminal zone of mesolimbic system (n. accumbens) nor of nigrostriatal system (striatum) nor in the adrenal glands. In conclusion, since the only consistent difference between NHE and NLE rats appears to be reactivity to spatial novelty, an hippocampus-dependent behavioral trait (selection trait), independent of altered activity in the sympathetic system or dopaminergic activity in the major dopaminergic brain systems, the usefulness of these strains as genetic model to test current hypotheses of spatial processor device(s) in the mammalian brain is supported.

3,4-Dihydroxyphenylacetic Acid↗

PubMed1992

Differential regulation of the nerve growth factor and brain-derived neurotrophic factor genes in L929 mouse fibroblasts.

Nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) are structurally related survival and differentiation factors for distinct sets of peripheral and central neurons. The regulation of NGF gene expression has been extensively studied in L929 mouse fibroblasts. L929 cells also express the BDNF gene. Northern blot hybridization analysis revealed 4 discrete BDNF mRNA species in L929 cells and rat hippocampus after induction of seizures with kainic acid. Serum as well as 12-O-tetradecanoyl phorbol-13-acetate (TPA) stimulated NGF and all 4 BDNF mRNAs in L929 cells. Treatment with both agents induced NGF mRNA to a much larger extent than the BDNF mRNAs. The induction of the BDNF mRNAs was rapid, with nearly maximal levels by 1 hr. In contrast, NGF mRNA induction occurred later and peaked at 4-6 hr. Both NGF and BDNF mRNA induction were inhibited by actinomycin D. Cycloheximide, on the other hand, inhibited only NGF but not BDNF mRNA induction. Corticosterone rapidly decreased NGF mRNA but not the BDNF mRNAs, and had no effect on seizure-induced NGF or BDNF mRNAs. Forskolin did not stimulate NGF or BDNF mRNAs. In contrast to NGF mRNA, forskolin did not interfere with the serum induction of BDNF mRNAs. These results demonstrate that 2 genes which encode closely related neurotrophic factors are differentially regulated in L929 cells. The molecular mechanisms which bring about this differential regulation remain to be elucidated.

Animals↗

PubMed1990

Transcriptional activation by the papillomavirus E6 zinc finger oncoprotein.

The introduction of the bovine (BPV) or human papillomavirus E6 gene into susceptible cells can result in their transformation, but there are few clues to the mechanism of action of the E6 gene. The characteristic features of E6 proteins are their small size (approximately 150 amino acids) and the potential to form two large zinc fingers. To determine if E6 can function as a transcription factor, the BPV E6 gene was fused to the sequence specific DNA binding peptide encoded by the BPV E2 gene. This chimeric E6-E2 protein trans-activated promoters that incorporated E2 binding elements in both rodent cells and Saccharomyces cerevisiae. In the absence of E6-E2 localization to the target promoter, trans-activation did not occur. Alteration of the cysteine residues at the base of each finger abrogated the transcriptional activity of the E6-E2 hybrids. These data demonstrated that the BPV E6 gene encodes a transcription activation domain and imply that a specific structure of the protein, most likely the zinc fingers, is critical for this function. Since these cysteine mutants are also transformation defective, E6 transcriptional functions may be required for its oncogenic activity.

Amino Acid Sequence↗

PubMed1990

Information system for biomedical equipment management in a wide-area environment.

An information system used in managing the inventory of equipment at the local health units (LHUs) of the Emilia Romagna region is presented. The system aims at efficient management of information on medical equipment and at supporting regional administrators in financial planning. The system uses 'classification files' and 'working files'. The classification files can be either defined at national (classification of producers, models and equipment types) or local (classification of suppliers and hospital departments) level. The working files are used to store all information necessary for the inventory of equipment in the local health unit (equipment inventory file) and results of automatic annual economic computations (residual values and amortisation quota file). Starting from data stored in the above-mentioned files the system can perform several procedures, such as control on data entry, economic computations and report printings. The main aspects of these operations are described in detail. Finally, some information on biomedical equipment of one of the largest local health units of the Emilia Romagna region, obtained from elaboration of system data, is shown and discussed.

Financial Management, Hospital↗

PubMed1990

A workstation-based system for 2-D echocardiography visualization and image processing.

Parameters of cardiac function can be drawn from the analysis of echocardiographic image sequences, especially the motion of the ventricular wall, heart wall thickness, and shape parameters. Automatic image analysis and visualization allows reduced manual operations and, above all, ensures objectivity and repetition of analysis, which is essential when one wishes to calculate parameters based on variations, i.e., on image sequence analysis. In this paper, a system and the related software package for interactive echocardiographic image analysis and visualization are illustrated and discussed. Furthermore, the full model for smoothing, edge enhancement, and contour detection is discussed and a new technique based on the heat anisotropic diffusion model is presented. The results of automatic detection of the left ventricle contours are presented and discussed.

Computer Systems↗

PubMed1990

Differential requirement for adenovirus type 12 E1A gene products in oncogenic transformation.

During the early period of infection, adenovirus type 12 E1A gene is expressed as overlapping, spliced mRNAs of 12 and 13S, which encode in-frame proteins of 235 and 266 amino acid residues (235R and 266R), respectively. To define the functions of these related products in the infection of human cells and transformation of rodent cells, we created single T-to-C transitions at the second base of each mRNA intron which specifically prevent splicing of the respective mRNAs. Mutant pm712 expresses only the 13S mRNA and 266R protein, while pm713 expresses only the 12S mRNA and 235R protein. By using these mutants, we showed that only the larger product is required for growth in human cells, including growth-arrested W138 cells, that the capacity to activate other viral genes (in human cells, at least) lies primarily with that protein, and that the 266R product is not required for autoregulation of its own transcription. In the presence of the 266R protein the 235R product was not required for complete and efficient transformation of a variety of rodent cells or for direct induction of tumors in rats, whereas in its absence the smaller product was insufficient for transformation or tumor induction. Finally, we showed that transformants resulting from infection of rodent cells with pm712 possess a fully-transformed phenotype and are tumorigenic. Previous studies with group C adenoviruses led to the conclusion that both E1A products are required for complete transformation; we conclude that with oncogenic serotype 12, only the 266R product is required for this process.

Adenovirus Early Proteins↗

PubMed1988

Continuous computerized monitoring of hemodynamic parameters during acetate dialysis, bicarbonate dialysis, and acetate-free biofiltration.

The effects of continuous, computerized, non-invasive hemodynamic monitoring on the appearance of intradialytic symptoms, aided by preventive therapeutic maneuvers, were evaluated in 30 critically ill patients undergoing regular acetate dialysis. The hemodynamic behavior was assessed by a system that interfaces a personal computer with a blood pressure monitor and to a transthoracic electrical impedance-measuring instrument. Monitoring allowed us to reduce significantly the frequency of some important intradialytic symptoms such as nausea, vomiting, and hypotension. The same monitoring system was used acutely to characterize differing hemodynamic behaviors during acetate dialysis (AD), bicarbonate dialysis (BD), and acetate-free biofiltration (AFBF). AD showed a prevalent vasodilation effect with a compensatory increase in heart rate and higher cardiac output values, which were not sufficient to maintain blood pressure stability. BD and AFBF were characterized by a more efficient vasoconstrictor effect and good hemodynamic stability. AFBF, despite a 1 h reduction in session length compared to BD, did not present significant differences in hemodynamic response resulting from session shortness or other technical changes.

Acetates↗

PubMed1988

Adenovirus type 12 E1B 19-kilodalton protein is not required for oncogenic transformation in rats.

The adenovirus type 12 mutants in700 and pm700 carry site-specific mutations within the reading frame encoding the E1B 19-kilodalton protein (19K protein) which prevent the production of the intact 19K protein. In cultures of human A549 cells, these mutants grow just as well as the wild-type virus does, but they display a large-plaque (lp), cytocidal (cyt) phenotype. DNA in these infected cells is not degraded, but at late times in human KB cells infected by the mutants, the mutants display a DNA degradation (deg) phenotype. The transformation phenotype of these mutants is also host range. Although the mutants are defective for transformation of the 3Y1 rat cell line, they transform rat and mouse primary kidney cells in vitro at wild-type efficiency and are capable of inducing tumors in rats. These results support the view that the type 12 E1B 19K protein is not obligatory for oncogenic transformation.

Adenovirus Early Proteins↗

PubMed1988

A digital computer model for optimal programming of hemodialytic treatment.

A mathematical model of hydroelectrolyte exchanges and arterial pressure regulation in the human body during dialysis has been set up. It is conceived as a tool for a new dialysis unit which will be able to "interpret" the signals supplied by suitable instruments connected to the patient and modify the machine set-points in real time in order to obtain clinical results defined by the physician. The main aim is the prevention of hypotensive episodes during treatment. An experimental protocol has been developed for parameter estimation of each patient during a single dialysis. Clinical tests illustrated the model's ability to fit the patient's state during dialysis. This is the first step in the more general task of validation of the model, necessary for the achievement of a closed-loop dialysis unit.

Computer Simulation↗

PubMed1985