Biomedical subjects

B S Hu

Publications and source records attributed to B S Hu.

60 records · Page 4Linked to original sources

PubMedDate not supplied

1991 I.I. Rabi Award. Estimating oxygen saturation of blood in vivo with MR imaging at 1.5 T.

The use of magnetic resonance (MR) imaging is investigated for noninvasively estimating the oxygen saturation of human blood (%HbO2) in vivo by means of relaxation characteristics identified in earlier MR spectrometry studies. To this end, a sequence is presented for determining the T2 of vascular blood in regions in which motions of the body and of the blood itself present a major challenge. With use of this sequence on a commercial 1.5-T whole-body imager, the relationship between the T2 and %HbO2 of blood is calibrated in vitro for the conditions expected in vivo. T2 varies predictably from about 30 to 250 msec as %HbO2 varies from 30% to 96%. T2 values measured in situ for vascular blood in the mediastinum of several healthy subjects qualitatively reflected the behavior observed in vitro. Estimates of %HbO2 for these vessels obtained with the in vitro calibration appear reasonable, particularly for venous blood, although difficulties arise in selecting the appropriate calibration factors. These encouraging initial results support a more systematic study of potential sources of error and an examination of the accuracy of in vivo measurements by comparison with direct measurements of %HbO2 in vessels.

Awards and Prizes↗

PubMedDate not supplied

Pulsed magnetization transfer spin-echo MR imaging.

Cross relaxation between macromolecular protons and water protons is known to be important in biologic tissue. In magnetic resonance (MR) imaging sequences, selective saturation of the characteristically short T2 macromolecular proton pool can produce contrast called magnetization transfer contrast, based on the cross-relaxation process. Selective saturation can be achieved with continuous wave irradiation several kilohertz off resonance or short, intense 0 degree pulses on resonance. The authors analyze 0 degree binomial pulses for T2 selective saturation, present design guidelines, and demonstrate the use of these pulses in spin-echo imaging sequences in healthy volunteers and patients. Using the phenomenologic Bloch equations modified for two-site exchange, the authors derive the analytic expressions for water proton relaxation under periodic pulsed saturation of the macromolecular protons. This relaxation is shown to be monoexponential, with a rate constant dependent on the saturation pulse repetition rate and the individual and cross-relaxation rates.

Brain↗

PubMedDate not supplied

Comparison of polymerase chain reaction and pulsed-field gel electrophoresis for the epidemiological typing of Campylobacter jejuni.

Seventeen sporadic Campylobacter jejuni enteritis cases occurred in Taichung City, Taiwan between July 1995 and September 1995. Pulsed-field gel electrophoresis (PFGE) and enterobacterial repetitive intergenic consensus (ERIC-1) primed polymerase chain reaction (PCR) techniques were compared for the epidemiological typing of the 17 C. jejuni isolates. Fourteen distinct PFGE fingerprint patterns were observed. Fifteen distinct PCR fingerprint patterns were demonstrated. Two clusters of isolates (isolates 5 and 6; isolates 10, 11 respectively) were found to be genetically indistinguishable by both methods. In conclusion, we consider that PFGE is a highly reproducible method for determining the relatedness among the C. jejuni isolates in this study, although their limited numbers of restriction fragments may reduce the discriminatory power. Although less reproducible than PFGE typing, ERIC-1 primed PCR can be used as a simple and rapid tool to discriminate different strains of C. jejuni.

Campylobacter Infections↗

PubMedDate not supplied

Use of pulsed-field gel electrophoresis in the analysis of recurrent Staphylococcus aureus infections in patients on continuous ambulatory peritoneal dialysis.

BACKGROUND/AIM: The purpose of this study was to evaluate pulsed-field gel electrophoresis (PFGE) for distinguishing between relapse and reinfection of Staphylococcus aureus infections in patients on continuous ambulatory peritoneal dialysis (CAPD). METHODS: Between July 1993 and May 1997, 4 patients with recurrent CAPD-associated infections caused by S. aureus we enrolled in this study. There were nine episodes of peritonitis, one episode of temporary double lumen catheter infection, and one episode of Hickman catheter infection. A total of eleven S. aureus isolates were collected from peritoneal fluid (n = 9) and blood (n = 2). PFGE typing was applied. RESULTS: In our study, from PFGE typing, the 11 S. aureus isolates were classified into seven patterns. Antibiogram profiling classified only four patterns. Patient A had a reinfection by another strain of S. aureus, and patient B had three episodes of peritonitis caused by the same strain of S. aureus due to exit site infections. Patient C had two episodes of CAPD peritonitis caused by two different strains, respectively. Patient D had four episodes of S. aureus infection (three CAPD peritonitis and one bacteremia); the first two episodes of peritonitis were caused by an identical strain of S. aureus, whereas the subsequent two infections were caused by other organisms. CONCLUSION: PFGE has a high discriminatory power and can be an assistant method to antibiogram profiling for distinguishing relapse from reinfection in CAPD-associated peritonitis.

Anti-Bacterial Agents↗

PubMedDate not supplied

Posttraumatic stress disorder in co-workers following exposure to a fatal construction accident in China.

To assess the mental disturbances induced by accidents at work, 41 male workers who had witnessed a fatal work accident were evaluated utilizing the criteria for posttraumatic stress disorder (PTSD) from the ICD-10 Classification of Mental and Behavioral Disorders. The Hamilton Depression Rating Scale (HDRS) was also administered to the exposed workers, as well as to 47 non-exposed construction-worker controls. The two groups were well matched with respect to age, years of employment, and years of education. They were all of Han sect; and lifestyles, incomes, and living conditions were similar. The exposed workers had a high rate of PTSD: 11 of 41 (26.8%) at one month and five of 39 (12.9%) four months after the fatal accident. The exposed groups' scores for depressive symptoms were significantly higher than those of the controls, including: 1) depressed mood, 2) guilt, 3) initial insomnia, 4) middle insomnia, 5) delayed insomnia, 6) decreased interest in work and other activities, 7) anxiety, 8) somatization, and 9) gastrointestinal symptoms (p < 0.05, p < 0.01, p < 0.001). Fatal work accidents, a major hazard in the construction industry, affect not only the victims but also the mental health of other workers. PTSD and associated emotional disorders related to exposure to serious work accidents deserve more attention for clinical and research purposes.

Accidental Falls↗

PubMedDate not supplied

A forward-viewing intravascular ultrasound catheter suitable for intracoronary use.

Current intravascular ultrasound (IVUS) catheters provide a transverse cross-sectional view of the blood vessel, thus limiting their ability to visualize severely stenosed or occluded vessels. Forward-viewing IVUS devices can overcome these limitations. Previously described forward-viewing IVUS catheters are mechanically complex, making them too bulky for use in coronary arteries. A new design for small-forward viewing IVUS catheters was developed. Using this design, flexible 5-Fr (1.6 mm diameter) and 8-Fr (2.6 mm diameter) prototype catheters up to 110 cm long, suitable for intravascular work, were constructed. Imaging of cadaver arterial segments was performed using these prototype catheters. Structures such as branches and plaque and features such as calcium were well seen with these catheters. Correlation of lumen dimensions measured with the IVUS catheters and by histology (HIST) was excellent: IVUS = 1.06 x HIST - 1.45 mm, r2 = 0.98. This new technology holds promise as a tool for guiding intravascular interventions.

Aorta↗