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Biomedical subjects

R Son

Publications and source records attributed to R Son.

15 recordsLinked to original sources
PubMed2001

Optical coherent reflectometry: a new technique to guide invasive procedures.

The success rate of percutaneous transluminal coronary angioplasty for chronic total arterial occlusions is still unsatisfactory. Inability to cross the lesion with a guidewire is a major cause of failure. Optical coherent reflectometry (OCR) is a new method of using laser light to measure the depth of tissue from the end of an optic fiber. This study tests whether an OCR prototype guidewire provides a guidance system that might be useful to assist reopening chronic total arterial occlusions. An OCR fiber optic within a 0.014" hypotube was developed using the interference pattern of two reflected light beams (wave length 1,300 nm). To determine if OCR can distinguish different tissue types, plaques of human lower extremity arterial segments were visually divided into three types (calcified, white, or yellow). The slope of the initial reflectance of the OCR curve was calculated and compared between the three groups. In six other arteries, the OCR wire was advanced longitudinally through occluded human artery segments in vitro. Guidewire position was determined by OCR and compared to the position of the guidewire tip observed simultaneously by intravascular ultrasound (IVUS) imaging. In 16 arterial surface segments, calcified plaques had a significantly steeper slope than white or yellow plaques (-227.2 +/- 82.2; -81.5 +/- 12.9; -103.6 +/- 19.6 dB/mm; P < 0.01). For the determination of the guidewire position, IVUS and OCR corresponded correctly in 82% of 28 measurements. Sensitivity and specificity of OCR for detection of plaque versus the media/adventitia boundary were 79% and 89%, respectively (P < 0.001). OCR can distinguish calcified from noncalcified plaque and may distinguish plaque from the media/adventitia boundary. This technology may be useful as a means to help navigate a guidewire safely through an occluded artery.

Arterial Occlusive Diseases↗
PubMed2000

Ultrastructural observation of nasal and pulmonary intracellular Pasteurella multocida A:3 in rabbits.

Sixteen 8- to 9-week-old Pasteurella multocida-free rabbits were divided into two equal groups. Eight rabbits in one group were inoculated intranasally with P. multoida type A:3. The other eight were inoculated intranasally with phosphate-buffered saline and used as controls. Nasal swabs taken before and after inoculation were cultured for bacterial isolation. Post-mortem nasal swabs and lung samples were cultured for bacteriological isolation. Nasal mucosa and lung samples were collected and processed for transmission electron microscopy. Pasteurella multocida was isolated from the nasal cavity of all infected rabbits and from the lungs of four infected rabbits. Degenerative ultrastructural changes in epithelial cells and endothelial cells were seen in the infected rabbits. Deciliation of the ciliated epithelium and hyperplasia of the goblet cells in the nasal mucosa were noted. Thickening of the alveolar septa due to hyperplasia of type II pneumocytes, swelling of the endothelial lining of capillaries and infiltration of inflammatory cells were also observed. Intracellular invasion of the nasal epithelial cells and of type II pneumocytes by the organism was observed. Coccobacilli were observed in membrane-bound vacuoles in the cytoplasm of these cells. The vacuoles were adjacent to the host-cell mitochondria and some of these vacuoles appeared to be fused to the mitochondrial membrane. Some type I pneumocytes with intracellular membrane-bound vacuoles containing bacterial cells showed protrusions, which appeared to detach into the alveolar lumina. These results indicated that P. multocida serotype A:3 in rabbits can invade the epithelial cell and cause structural changes in the interstitium, epithelium and endothelium. Heterophils and macrophages appear to play important roles in tissue injury.

Animals↗
PubMed2000

In vitro study of Pasteurella multocida adhesion to trachea, lung and aorta of rabbits.

In vitro experiments were undertaken to study the adhesion and colonization to tracheal mucosa, lung and aorta explants from freshly killed rabbits of two different strains of Pasteurella multocida. Serotype A:3 (capsulated, fimbriae +, haemagglutination -, dermonecrotic toxin -) isolated from a rabbit with rhinitis, and serotype D:1 (non-capsulated, fimbriae +, haemagglutination +, dermonecrotic toxin +) isolated from a dead rabbit with septicaemia, were used. When the explants were observed under the scanning electron microscope, the type D strain was highly adherent to trachea and aorta explants compared to the type A strain. Adhesion to lung explants was best achieved by the type A strain after 45 min incubation, but after 2 h incubation no significant difference was observed between the strains. Our data indicate that the presence of fimbriae and the absence of capsule seem to enhance the adherence of P. multocida type D strain to tracheal tissue. The capsular material of P. multocida type A strain and the toxin of the type D strain seem to influence the adherence to lung tissue in rabbit. Adhesion of strain D to aorta may indicate the expression of receptors on the endothelium to that strain and may also explain the ability of certain strains to cause septicaemia.

Animals↗
PubMed1999

Does use of intravascular ultrasound accelerate arteriopathy in heart transplant recipients?

BACKGROUND: Intravascular ultrasound (IVUS) is a sensitive method for assessing allograft vasculopathy in heart transplant recipients, but it is not known whether this instrumentation traumatizes the transplanted arteries and affects progression of arteriopathy. METHODS AND RESULTS: Yearly coronary angiograms were obtained in 86 patients who underwent heart transplantation between January 1991 and May 1995. Patients were divided into 3 groups: (1) no IVUS performed after transplantation (group 1, n = 47); (2) IVUS of the left anterior descending artery (LAD) performed only at year 1 (group 2, n = 13); and (3) IVUS of the LAD performed at both baseline (within 2 months after transplantation) and year 1 after transplantation (group 3, n = 26). Coronary angiography measurements of lumen diameter were performed at 5 segments along the length of the LAD and left circumflex artery (LCX) from baseline through the second-year studies except in group 2, which did not receive a baseline angiogram; IVUS measurements were obtained at 10 cross sections from each artery. At baseline, there was no significant difference in vessel diameter for either the LAD or the LCX artery between the IVUS (group 3) and no IVUS (group 1) groups. Within each group, the lumen of both the LAD and LCX narrowed from baseline to year 1 (group 1: 3.3 +/- 0.6 mm to 2.8 +/- 0.5 mm in LAD, P =.001; 3. 3 +/- 0.6 mm to 3.0 +/- 0.5 mm in LCX, P =.006; group 3: 3.5 +/- 0.7 mm to 3.1 +/- 0.6 mm in LAD, P =.01; 3.1 +/- 0.6 mm to 2.8 +/- 0.5 mm in LCX, P = 0.07), but there were no significant differences between the instrumented artery (LAD) and control artery (LCX) or further changes observed at year 2. There were also no significant differences in the percent reductions at year 1 and year 2 between arteries or between groups. By IVUS, from baseline to year 1 in group 3, the plaque cross-sectional area (CSA) increased (1.6 +/- 1. 9 to 2.3 +/- 1.7 mm(2), P <.0001), the lumen CSA decreased (12.7 +/- 3.7 to 11.7 +/- 3.3 mm(2), P =.04), and the maximum lumen diameter decreased (4.2 +/- 0.6 to 4.0 +/- 0.6 mm, P =.04). CONCLUSIONS: The use of IVUS is not associated with acceleration of arteriopathy in heart transplantation recipients. Luminal narrowing occurs predominantly during the first year after transplantation. There was no significant change in lumen dimensions during the second year.

Adult↗
PubMed1999

Isolation and molecular characterization of vancomycin-resistant Enterococcus faecium in Malaysia.

Nineteen strains of vancomycin-resistant Enterococcus faecium isolated from 10 of 75 (13.3%) tenderloin beef samples were examined for resistance to selected antibiotics, presence of plasmids, and genetic diversity by random amplification of polymorphic DNA analysis. All strains showed multiple resistant to the antibiotics tested. Multiple antibiotic indexing of the vancomycin-resistant E. faecium strains showed that all (100%) originated from high risk contamination environments where antibiotics were often used. Plasmids ranging in size from 1.5 to 36 megadalton were detected in 15 of 19 (79%) strains. Thus, three plasmid profiles and eight antibiotypes were observed among the E. faecium strains. A high degree of polymorphism was obtained by combining the results of the two primers used; with the 19 E. faecium strains being differentiated into 19 RAPD-types. These preliminary results suggest that RAPD-PCR has application for epidemiologic studies and that resistance patterns and plasmid profiling could be used as an adjunct to RAPD for the typing of E. faecium in the study area.

Animals↗
PubMed1999

Video networking of cardiac catheterization laboratories.

BACKGROUND: The purpose of this study was to assess the feasibility and accuracy of a video telecommunication network to transmit coronary images to provide on-line interaction between personnel in a cardiac catheterization laboratory and a remote core laboratory. METHODS: A telecommunication system was installed in the cardiac catheterization laboratory at Kaiser Hospital, Los Angeles, and the core laboratory at the University of California, Irvine, approximately 40 miles away. Cineangiograms, live fluoroscopy, intravascular ultrasound studies and images of the catheterization laboratory were transmitted in real time over a dedicated T1 line at 768 kilobytes/second at 15 frames/second. These cases were performed during a clinical study of angiographic guidance versus intravascular ultrasound (IVUS) guidance of stent deployment. During the cases the core laboratory performed quantitative analysis of the angiograms and ultrasound images. Selected images were then annotated and transmitted back to the catheterization laboratory to facilitate discussion during the procedure. RESULTS: A successful communication hookup was obtained in 39 (98%) of 40 cases. Measurements of angiographic parameters were very close between the original cinefilm and the transmitted images. Quantitative analysis of the ultrasound images showed no significant difference in any of the diameter or cross-sectional area measurements between the original ultrasound tape and the transmitted images. The telecommunication link during the interventional procedures had a significant impact in 23 (58%) of 40 cases affecting the area to be treated, the size of the inflation balloon, recognition of stent underdeployment, or the existence of disease in other areas that was not noted on the original studies. CONCLUSIONS: Current video telecommunication systems provide high-quality images on-line with accurate representation of cineangiograms and intravascular ultrasound images. This system had a significant impact on 58% of the cases in this small clinical trial. Telecommunication networks between hospitals and a central core laboratory may facilitate physician training and improve technical skills and judgement during interventional procedures. This project has implications for how multicenter clinical trials could be operated through telecommunication networks to ensure conformity with the protocol.

Angioplasty, Balloon, Coronary↗
PubMed1998

Comparison of the sheath delivery system versus bare stenting for coronary stent implantation.

Outside the United States, Palmaz-Schatz coronary stents are implanted by hand-crimping the stent to a high pressure balloon without the use of a protective sheath. This lowers the delivery profile, increases the ease of deployment, and ensures that the postdilatation balloon is centered on the stent. To assess this bare stenting technique, 209 patients were retrospectively analyzed: 92 patients (107 lesions) with the sheath protected stent delivery system (SDS) and 117 patients (150 lesions) with the bare stent approach. The number of balloons used per lesion in the bare stent group was significantly less than in the SDS group (1.9 +/- 0.6 vs. 3.8 +/- 1.2, P < 0.0001). In addition, the procedure time in the bare stent group was significantly shorter than in the SDS group (106 +/- 55 vs. 134 +/- 60 min, P = 0.001). There was no difference in frequency of adverse events or stent displacement during the procedure. The bare stenting technique decreases the procedure time, reduces the number of balloons used, and is as safe as the SDS approach.

Aged↗
PubMed1998

Note: characterization of Vibrio cholerae O139 Bengal isolated from water in Malaysia.

Four Vibrio cholerae O139 Bengal strains isolated from surface water were characterized by antibiotic resistance, plasmid profile, presence of cholera toxin gene and random amplification of polymorphic DNA (RAPD) analysis. All four strains exhibit multiple resistance towards the antibiotics tested with a multiple antibiotic resistance index of 0.5-0.66, and harboured a 2.0 MDa non-conjugative plasmid. The Vibrio cholerae O139 Bengal were positive for the cholera toxin gene. Antibiotyping and random amplification of polymorphic DNA analysis with four primers proved to be useful in discriminating the isolates. RAPD proved to be more sensitive. These results reveal that there is significant genetic diversity among the Vibrio cholerae O139 Bengal strains studied.

Malaysia↗
PubMed1997

Video networking of cardiac catheterization laboratories.

UNLABELLED: A video telecommunication network was established to transmit coronary images between a cardiac catheterization laboratory and a remote core laboratory. In 40 patients during interventional procedures, cine angiograms, live fluoroscopy, intravascular ultrasound studies, and images of the cath lab were transmitted in real time over a T1 line at 768 kbits/second at 15 frames/second. RESULTS: Measurements of angiographic and intravascular ultrasound parameters were very close between the original studies and the transmitted images. The telecommunication link up during the interventional procedures had a significant affect in 58% of cases.

Cardiac Catheterization↗
PubMed1997

Antibiotic resistance and plasmid profile of Aeromonas hydrophila isolates from cultured fish, Telapia (Telapia mossambica).

Strains of Aeromonas hydrophila isolates from skin lesions of the common freshwater fish, Telapia mossambica, were screened for the presence of plasmid DNA by agarose gel electrophoresis and tested for susceptibility to 10 antimicrobial agents. Of the 21 fish isolates examined, all were resistant to ampicillin and sensitive to gentamycin. Most isolates were resistant to streptomycin (57%), tetracycline (48%) and erythromycin (43%). While seven of 21 isolates harboured plasmids, with sizes ranging from 3 to 63.4 kilobase pair (kb), it was only possible to associate the presence of a plasmid with antibiotic resistance (ampicillin and tetracycline) in strain AH11. Both the plasmid and the associated antimicrobial resistance could be transferred to an Escherichia coli recipient by single-step conjugation at a frequency of 4.3 x 10(-3) transconjugants per donor cell.

Aeromonas hydrophila↗
PubMed1997

Conjugal transfer of plasmids and antibiotic resistance among Escherichia coli isolated from animals in a rural area in Sarawak (Malaysia).

Thirty-six strains of Escherichia coli isolated from animals in Bario, a remote area in Sarawak, Malaysia, were examined for presence of plasmid DNA and their susceptibility to nine antimicrobial agents. Of the total 36 isolates, five bovine and six canine isolates were found to contain plasmid DNA ranging in sizes from 2.6 to 70 kilobases. All were susceptible to chloramphenicol, erythromycin, gentamicin, nalidixic acid and neomycin but resistance to ampicillin (47%), erythromycin (19%), streptomycin (25%) and tetracycline (11%) was observed. Resistance was associated with carriage of a 47 kb (SC98), 70 kb, (SC133) and 56 and 4.6 kb (SC119) plasmids which were transmissible to the Escherichia coli K12 recipient. It is concluded that animals form a potential reservoir of R plasmids carrying E. coli in the study area.

Animals↗
PubMed1996

[Shone's syndrome].

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Aortic Coarctation↗