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Biomedical subjects

M Arditi

Publications and source records attributed to M Arditi.

51 records · Page 3Linked to original sources
PubMed1988

Spiramycin alone and in combination with trimethoprim against Haemophilus influenzae.

Following determination of MICs and MBCs of spiramycin and trimethoprim by the broth microdilution method for 16 typable (including 13 type b) and 15 nontypable H. influenzae isolates, bactericidal synergy was tested by the chequerboard method and the time-kill curve methods. Nineteen (13 typable and six nontypable) of 31 strains demonstrated synergy by the chequerboard method. Ten strains showed indifference, and two manifested antagonism. In contrast, 12/13 strains tested by the time-kill method showed synergy and 1/13 demonstrated indifference. Of note was the finding that seven isolates that showed indifference by chequerboard method (three typable, four nontypable) manifested synergism by the kill-curve method. Of the two nontypable strains showing antagonism by chequerboard, one manifested synergy and the other indifference by the time-kill method. Our studies show that in-vitro synergy between spiramycin and trimethoprim against H. influenzae strains is frequently demonstrable. In-vivo studies may be helpful in confirming these in-vitro observations.

Drug Therapy, Combination↗
PubMed1988

Non-invasive measurement of internal diameter of peripheral arteries during the cardiac cycle.

An ultrasonic device was developed for continuous monitoring of the internal diameter of human peripheral arteries. The diastolic internal diameter of the radial artery measured in 10 supine normotensive subjects averaged 2.36 +/- 0.12 mm (mean +/- s.e.) and the change in diameter during the pulse wave was 0.037 +/- 0.003 mm. It was surprising to find that when the transducer was used to apply pressure on the radial artery, the difference between the systolic and the diastolic diameter was significantly increased while the diastolic diameter was reduced. This method therefore allows continuous, accurate and non-invasive measurement of the internal diameter of the human radial artery.

Arteries↗
PubMed1988

Pediatric cerebral abscess.

Fifty-four consecutive cases of children with cerebral abscess from 1958 to 1987 are reviewed. Their average age was 6.6 years, ranging from 3 days to 19 years. A wide range of organisms and underlying diseases was encountered. The predominant mode of surgical therapy was craniotomy with resection of the abscess. Aspiration and craniotomy with drainage-evacuation were also employed in our series. No underlying disease was found in 10 (19%) of the children. Cyanotic heart disease (CHD) was present in 13 (24%) of the children. Four children had dental abscesses and 1 had otitis media. Seven (13%) children had abscesses secondary to hydrocephalus/shunt infections. Sinusitis and otitis accounted for 5 cases (9%). Four children (7%) had tuberculomas. One abscess was associated with a nasal dermal sinus and one was congenital. Fourteen (26%) patients had negative cultures. Fourteen (26%) abscesses contained streptococci of various types. Staphylococci were found in only 5 (9%) of the abscesses. The congenital abscess was caused by salmonella. Two abscesses (7%) were fungal. Both of these patients died. Six children (11%) were treated without surgical intervention. Three of them died. Forty-eight children had surgical intervention; 12 underwent aspiration, 14 underwent open evacuation of the abscess, and 22 had abscesses resected. Mortality in the aspiration group was twice that of the evacuation or resection group (17, 7 and 9%), respectively). The factor which correlated best with mortality was the patient's clinical status on admission. The advent of CT scan at our facility improved mortality by facilitating accurate diagnosis and surgical intervention. Overall mortality rates decreased from 31 to 5.7% and surgical mortality fell from 21 to 2.9%.

Adolescent↗
PubMed1987

Imaging studies of the cadaver hand using transmission ultrasound.

Ultrasonic transmission imaging has already demonstrated potential for evaluating structures in the hand. In this study, a cadaver hand was imaged using a transmission scanner with improved imaging capability. The hand was then frozen and serially sectioned and comparisons were made between the sectional anatomy and the corresponding image. Bone (in silhouette), muscle, cartilage, and tendon were visualized with high resolution.

Bone and Bones↗
PubMed1985

Ultrasonic reflex transmission imaging.

Reflex Transmission Imaging (RTI) is a new imaging method by which orthographic transmission images can be made using augmented B-mode equipment. Conventional transmission imaging requires acoustic coupling to large areas on both sides of the body, whereas RTI can be performed from one side with a single, small transducer probe. In this mode, transmission images in a plane normal to the beam are made by integrating the reverberations from beyond the focal zone of the transducer. These reverberations provide, in essence, a source of incoherent insonification from behind the focal plane. Preliminary in-vitro images have been made using a computer-interfaced rectilinear scanner with a 1-inch diameter f/2.8 transducer. The images have good resolution and signal-to-noise ratio, and a short depth-of-field. Backscatterer inhomogeneity is well smoothed. Transmission images provide information that is complementary to B-scans. RTI will allow both to be made with the same instrument and presented on the same display. A time-gated reflection C-scan could be generated simultaneously. Other RTI modes, including an attenuation B-mode, also are discussed.

Animals↗
PubMed1983

Computer simulations of speckle in B-scan images.

The granularity or speckle in medical ultrasound images tends to mask the presence of small lesions. As well, artifactual filling in of anechoic regions such as cysts, reduces the diagnostic potential of the images. These effects depend not only on the acoustic properties of the tissue but also are strongly influenced by the imaging system, especially the transducer geometry. To study the effect of the transducer on the final B-scan image, a computer model has been developed simulating the interaction of ultrasound with a simple scattering medium. This model, incorporating the position dependence of the point response of the transducer, is based on single scattering from a collection of points positioned randomly in a three-dimensional volume. Using this approach, B-scan images showing speckle have been generated for different transducer geometries. Inclusion of a 2.6 mm void mimicking a cyst within the three-dimensional scattering volume has allowed us to predict the cyst contrast in the image for the different transducer systems. Experimental B-scan images of a scattering phantom were obtained using the different pulse echo systems. Quantitative assessment using first and second order statistics of the images shows good agreement between experiment and theory.

Acoustics↗
PubMedDate not supplied

Breast imaging with a conical transducer/annular array hybrid scanner.

A hybrid conical scanner consisting of a 37.5 degrees, 4 MHz conical receiver and a five element 5 cm dia. 4 MHz annular array transmitter has been developed for breast imaging. The ultrasound fields and imaging characteristics of three interesting geometries are compared. These are: (1) the annular array used in conventional pulse-echo mode, (2) the conical transducer used in combination with the full annular array and (3) the conical transducer used in combination with the center element of the annular array (simple conical scanner). Both conical systems provide extremely narrow (0.3 mm) beamwidths at -6dB but the cone/annular array combination has significantly improved sidelobe characteristics compared with the simple conical scanner. The combination of high resolution and reasonable sidelobe levels for the cone/annular array hybrid results in images with very fine speckle patterns and good definition of small structures. Breast images from young normal volunteers show that this approach has considerable potential for clinical application.

Adult↗
PubMedDate not supplied

Group C beta-hemolytic streptococcal infections in children: nine pediatric cases and review.

Streptococci of Lancefield group C colonize healthy individuals but infrequently cause invasive disease. Eight pediatric cases of infection due to group C streptococci were identified in a retrospective survey of a recent 6-year period at a children's hospital. An additional case of group C meningitis diagnosed in 1975 was included. These nine cases and 22 pediatric cases from the literature are presented to illustrate important points with respect to clinical presentations and complications and to show that these organisms can cause serious, sometimes fatal infection: pneumonitis, sinusitis, septicemia, endocarditis, osteomyelitis, and meningitis. Group C streptococci are described in terms of their biochemical properties, the infections they cause in animals, and their tendency to produce disease in humans. With increasingly frequent serologic grouping of non-group A beta-hemolytic streptococci, recognition of the role of specific non-group A streptococci is likely to increase. The antimicrobial agent of choice for infections due to group C streptococci is penicillin G. The minimum inhibitory and minimum bactericidal concentrations for the organism should be determined since penicillin tolerance may occur and may be responsible for the slow response to penicillin therapy in some cases.

Adolescent↗