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Biomedical subjects

C Lamberti

Publications and source records attributed to C Lamberti.

85 records · Page 5Linked to original sources
PubMed1979

[Left ventricular volume measurement; the accuracy of the measurement].

Volume angiography is a widely diffused technique in hemodynamic laboratories despite several factors which limit the validity of the method. We have evaluated three of these factors: a) indefiniteness in the identification of the contour of the left ventricular cavity on the projected image; b) indefiniteness due to the reproducibility in tracing the contour of the left ventricular cavity by the same operator; c) indefiniteness related to the geometrical assumption (ellipsoid of revolution). The indefiniteness, given as per cent variation from the mean value, has been determined for the diastolic as well as systolic phase. The maximal possible indefiniteness, for diastole and systole, in contours identification in 15 cases has been found to be +/- 11.3% and +/- 24% of the mean volume. Intra observer reproducibility evaluated outlining 30 times the left ventricular contour has been equal to a mean difference from the mean volume of +/- 1.2% for diastole and +/- 4% for systole. The mean difference of the mean volume calculated with the area-lenght method (ellipsoid geometry) from the volume calculated with the Simpson rule has been, on 15 cases, equal to 4% in diastole and 11% in systole. This high level of indefiniteness, mainly for the systolic phase, must be considered before giving a value excessively precise to the volume data obtained with angiography. On the other hand, the method retains an orientative meaning extremely useful in clinical evaluation.

Angiocardiography↗
PubMedDate not supplied

Identification of the three-element windkessel model incorporating a pressure-dependent compliance.

A new one-step computational procedure is presented for estimating the parameters of the nonlinear three-element windkessel model of the arterial system incorporating a pressure-dependent compliance. The data required are pulsatile aortic pressure and flow. The basic assumptions are a steady-state periodic regime and a purely elastic compliant element. By stating two conditions, zero mean flow and zero mean power in the compliant element, peripheral and characteristic resistances are determined through simple closed form formulas as functions of mean values of the square of aortic pressure, the square of aortic flow, and the product of aortic pressure with aortic flow. The pressure across as well as the flow through the compliant element can be then obtained so allowing the calculation of volume variation and compliance as functions of pressure. The feasibility of this method is studied by applying it to both simulated and experimental data relative to different circulatory conditions and comparing the results with those obtained by an iterative parameter optimization algorithm and with the actual values when available. The conclusion is that the proposed method appears to be effective in identifying the three-element windkessel even in the case of nonlinear compliance.

Algorithms↗
PubMedDate not supplied

3D modeling of phased array generated ultrasounds in lossy media.

A general algorithm for three-dimensional (3D) modeling of acoustic fields generated by phased array transducers and propagating in uniformly lossy media is introduced and illustrated also with the help of specific examples. Applications of the method are foreseen in the analysis and the design of transducers for echographic applications in order to evaluate and/or optimize their performances.

Acoustics↗
PubMedDate not supplied

A new model to estimate the appropriate staff for a clinical engineering department.

This study points out that the Clinical Engineering Department (CED) can provide expertise for the improvement of healthcare services if the size of the CED is appropriately determined; that is when the number of engineers, technicians and administrative staff is suitable for the activities that they are intended to carry out and for the amount of equipment they must manage. The paper presents a simple and flexible model where the staff is estimated according to the activities that need to be carried out by the CED and according to the amount of biomedical equipment being managed. Several examples of application and comparisons with the results provided by other models are reported and discussed.

Biomedical Engineering↗
PubMedDate not supplied

A novel missense mutation in the DNA mismatch repair gene hMLH1 present among East Asians but not among Europeans.

In a search for germline mutations in the DNA mismatch repair genes hMSH2 and hMLH1 in Chinese patients with colorectal cancer we identified a novel missense mutation (V384D) in exon 12 of the hMLH1 gene in 4 out of 26 individuals. This mutation had not been observed in any of 109 German patients who either fulfill the clinical criteria of hereditary nonpolyposis colorectal cancer or had developed colorectal cancer at an early age. In a second series of experiments, DNA samples of 80 healthy. Japanese and 100 healthy Germans were examined for the presence of the V384D mutation. It was observed in 4 Japanese, but in none of the German individuals. Thus, the V384D mutation seems to be confined to the East-Asian population. Since this missense mutation occurs at a less conserved region of the hMLH1 gene, it may represent a nonfunctional polymorphism. However, a role in the pathogenesis of colorectal cancer cannot be ruled out from the present study.

Adaptor Proteins, Signal Transducing↗
PubMedDate not supplied

Cirrhosis negatively affects the efficiency of serologic diagnosis of Helicobacter pylori infection.

In cirrhosis, Helicobacter pylori infection may be implicated, together with portal hypertension, bile reflux and alcohol abuse, in damage to gastric mucosa. Aim of this study was to define the influence of non-alcoholic liver disease on the incidence of Helicobacter pylori infection and on the diagnostic accuracy of specific serology. Enrolled in the study were 232 individuals, 105 also had cirrhosis. Infection by Helicobacter pylori, diagnosed by a positive concordance of quick urease test and histology, was detected in 97 (48 with cirrhosis) out of 184 patients. Severe gastritis was more frequent in patients with Helicobacter pylori infection than in patients without. Cirrhosis did not significantly affect the prevalence of Helicobacter pylori infection or the histological features of gastritis. Specific anti-Helicobacter pylori IgG and IgA assay (Bio-Rad GAP test) was used for serological diagnosis. Anti-Helicobacter pylori IgG showed a high sensitivity (85% in cirrhotics, 89% in non-cirrhotics) and low specificity being more evident in cirrhotics (38% vs 56% non-cirrhotics). Serum specific IgA showed low sensitivity (approximately 25% in both groups) and specificity of 79% in cirrhotics vs 84% in non-cirrhotics. In conclusion, non-alcoholic cirrhosis does not affect the incidence of Helicobacter pylori infection and the histological features of chronic gastritis but does decrease diagnostic efficiency of serological tests for Helicobacter pylori.

Antibodies, Bacterial↗