Biomedical subjects
Publications and source records attributed to J L Bao.
Rotor-like ZnO was grown from a mixture of rod-like ZnO powder and a saturated Zn(OH)(4)(2-) solution under moderate hydrothermal conditions at 100 degree C, in which the precursor rod-like ZnO crystal plane acts as a matrix core, and the branched nanorods showed fast epitaxial growth on the six directions around the prism core.
Magnetic fields (MFs) of various characteristics can lead to plethora effects in biological system. From a molecular point of view, we hypothesized that there must be a fundamental difference in gene expression between the MF exposed and the unexposed cell. To identify the classes of genes that are regulated, 0.8 mT 50 Hz MF-induced changes in gene expression were examined in a Daudi cell culture using differential display and reverse transcriptase-polymerase chain reaction. A candidate cDNA (signatured as MF-CB) that was observed in the sham-exposed but not in MF-exposed cultures was recovered and reamplified. After verification by Northern blot, the cDNA was cloned and sequenced. It was found that 254-base pair of 5'-end MF-CB cDNA clone was identical to gcs in open reading frame (ORF) range. Based on the preliminarily sequence, the prolonged length of 5'-end MF-CB cDNA was obtained by PCR amplification and its sequence analysis showed the same results as its original fragment. In order to further determine whether MF-CB cDNA is from gcs, two Northern blots were probed with gcs and MF-CB cDNA, respectively, and the data revealed signals of the same size and expression pattern on the two probe filters, which demonstrated that MF-CB is an EST (expression sequence tag) of gcs. gcs is a gene, identified recently (GenBank accession number D89866), encoding ceramide glucosyltransferase (GCS), which has been implicated as a causal element in human cell growth and differentiation. In an additional experiment, time-dependent changes in the transcription of gcs induced by 0.8 mT MF were observed by Northern blot with a sharp and reproducible inhibition effect after 20 min exposure and a reduction after 20-24 h exposure. The study demonstrates for the first time that 50 Hz MF can lead to changes in gcs transcription, which provides a new clue to elucidate the mechanism by which MF influence cell growth and differentiation.
Based on the experimental observations, an electrical circuitry model for a rectifying gap junction was developed in previous work. In order to show the physiological function for each element in the model, a theoretical analysis is carried out in this report. The results indicate that the gap junctional capacitance Cj newly introduced into the model plays a major role in determining the duration increase, the peak attenuation, and the peak delay on the postmembrane action potential. Also, a comparison between the newly proposed model and the widely accepted kinetic model by Giaume is made. The results show that the electrical circuitry model can not only describe the characteristics of Giaume's model but also allow the interpretation of some experimental phenomena that were not reflected in other gap junctional models.
Experimental observation on the relation between the apposition of scaphoid fracture surfaces and wrist position showed that fracture reduction could be achieved when the wrist was placed in a position from 15 degrees radial deviation to 15 degrees ulnar deviation provided that the wrist assumed certain amount of extension. The principle was that the more the wrist was radially deviated, the more the extension was needed. Fracture displacement occurred regularly and could be classified into three types, which were related to different loading patterns on the distal scaphoid.
Rationale and plans are described for a collaborative case-control study of large bowel cancer among Chinese-Americans in Los Angeles and the San Francisco Bay Area and among Chinese in Zhejiang Province, People's Republic of China. A common protocol and questionnaire will be used during personal interviews of approximately 400 Chinese and 300 Chinese-American patients with histologically confirmed adenocarcinoma of the colon or rectum and 2,100 Chinese and Chinese-American controls. Controls will be matched to patients on age, sex, and community of residence. The information requested from subjects will permit testing of hypotheses relating colorectal cancer risk to: dietary factors, including intake of fat (saturated and unsaturated), animal protein, fiber, and vitamins A and E and ascorbic acid; physical activity levels and body mass index; reproductive factors among women; history of bowel disease; and family history of cancer. The information requested of Chinese-American subjects will also permit testing of hypotheses relating cancer risk to such migrant factors as United States versus Chinese nativity, duration of residence in the United States, and Chinese province of ancestry. These factors will be tested for associations with cancers of the colon and rectum separately and with cancers of the large intestine as a whole. We will examine sex and geographic differences in relative risks for etiologic factors, location of tumors within the large bowel, histologic subtype of adenocarcinoma, and frequency of accompanying polyps.