Search PubMed⌕ Search

Biomedical subjects

B Li

Publications and source records attributed to B Li.

At least 721 records · Page 40Linked to original sources
PubMed1993

[Preliminary report on the results of nutrition prevention trials of cancer and other common diseases among residents in Linxian, China].

To examine whether vitamin/mineral supplementation may lower mortality and incidence from human cancer and mortality from other diseases as well as to provide the scientific basis and feasible approach for human cancer prevention and control, between 1982-1991 scientists from China and USA conducted two randomized, double-blind, and placebo-controlled nutrition intervention trials in Linxian, China, where the esophageal/gastric cardia cancer mortality rates are among the highest in the world and there is suspicion that the population's chronic deficiencies of multiple nutrients are etiologically involved. In the first trial, the Dysplasia Trial, 3,318 individuals with a cytologic diagnosis of esophageal dysplasia received daily 26 vitamin/mineral supplements or placebos for 6 years; The second trial, the General Population Trial, involved 29,584 individuals and used an one-half replicate of a 2(4) fractional factorial design which randomized to 8 groups for testing the effects of daily supplementation of 4 different vitamin/mineral combinations and placebo for a period of 5 1/4 years. Compliance assessed by monthly pill counts and quarterly monitoring of biochemical assays indicated that the participant compliance was excellent. As endpoints of the trials, incident cancers and deaths were identified through all medical facilities in local areas, supplemented by special endoscopy and cytology examinations, and confirmed by 3-level review groups. A total of 323 deaths occurred during 6 year period among participants in the dysplasia trial, and 2,127 deaths from the general population trial during 5 1/4 years. Besides, an eye examination, which included detailed lens evaluations, was included in the extensive re-examination protocol to ascertain whether use of the supplements had affected the risk of developing age-related cataracts among participants in the two trials. Results from Dysplasia Trial indicated that after 6 years of daily supplementation with multiple vitamins and minerals, total mortality among those in the active treatment group was slightly (9%) lower than in the placebo group; and deaths of esophageal cancer also declined by 17%, as well as a sizeable reduction in cerebrovascular disease mortality (near 40%) was seen, though none was statistically significant. However, intervention had decreased prevalence of eye nuclear cataract (43%) (P < 0.01). The findings from the General Population Trial provide support for the hypothesis that intake of specific micronutrients may inhibit cancer development. Significant reduction of total mortality (9%), cancer mortality (13%), gastric cancer mortality (20%), and mortality of the other cancers (19%) occurred among those receiving beta-carotene/vitamin E/selenium supplementation (P < 0.05). Patterns of cancer incidence, based on 1307 cases, generally resembled those for cancer mortality.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1993

Ulnar neuropathy after median sternotomy.

Ulnar neuropathy is a known complication of median sternotomy surgery, and its precise cause is not clear. The authors hypothesize that a "double-crush" phenomenon caused by intraoperative compression of the brachial plexus occurs in a patient with preexisting, previously undiagnosed slowing of ulnar nerve conduction. Eighty-four arms in 42 patients scheduled for cardiac surgery were studied. Pre- and postoperative history and physical examinations were performed by separate blinded examiners; however, the nerve conduction studies were performed by a single examiner. Fifteen arms (18%) in 11 patients (26%) clinically demonstrated postoperative neuropathy. After surgery, all symptomatic patients had considerable slowing of their preoperative conduction studies. A direct correlation appears to exist between preoperative slowing of ulnar nerve conduction and postmedian sternotomy neuropathy. A careful preoperative evaluation including nerve conduction studies may detect the predisposed patient; the surgeon attempting postoperative cubital tunnel decompression is cautioned that the lesion may not be an isolated one.

Adult↗
PubMed1993

Skeletal muscle metabolic enzymes are altered by hyperbaric oxygenation treatments.

To test whether repeated HBO exposures would increase activity of skeletal muscle metabolic enzymes, 27 rabbits (3 groups) were exposed 90 min/day, 5 days/wk to either 100% O2 at 243 kPa (HBO), 100% O2 at 101 kPa (HIO), or 21% O2 at 101 kPa (CON). Four animals per group were killed after 2 wk treatment, and the remaining five per group were killed after 8 wk of treatment. Soleus, plantaris, and tibialis anterior muscles were removed, and the activities of adenylate kinase, alpha-glycerophosphate dehydrogenase, and citrate synthase were measured. After 8 wk there was no difference in enzyme activity between groups for either plantaris or tibialis anterior. In the soleus after 8 wk there was no difference between groups in adenylate kinase activity, but alpha-glycerophosphate dehydrogenase activity was 56% greater (P < 0.05) in HBO than in HIO and 50% greater than in CON, and citrate synthase activity in HBO was 24% greater (P < 0.05) than that in HIO and 36% greater than that in CON. Inasmuch as the soleus is a postural muscle, these results suggest that long-term HBO treatments can increase enzyme activity in an actively contracting muscle.

Adenylyl Cyclases↗
PubMed1993

Use of the two-hybrid system to identify the domain of p53 involved in oligomerization.

We used a yeast-based genetic assay, the two-hybrid system, to characterize the domain of the tumor-suppressor p53 involved in oligomerization. This assay relies on the reconstitution of the function of a transcriptional activator, the yeast GAL4 protein, via the interaction of a protein fused to the DNA-binding domain of GAL4 with a protein fused to the transcriptional activation domain of GAL4. We show by a reconstruction experiment that this approach could detect the interaction of p53 deleted for its N-terminal activation domain with SV40 large T antigen. We then searched a library of human proteins present as activation domain hybrids for proteins that can interact with the hybrid of p53 with the DNA-binding domain. This search identified 36 plasmids containing the p53 gene, representing 10 different classes. These results provide an additional in vivo demonstration of p53 oligomerization. The smallest p53 fragment identified from screening the library contained only amino acids 331-393, indicating that this small C-terminal fragment is sufficient to mediate oligomerization. In addition, a mutant p53 protein could bind to the wild-type protein in this assay, providing support for the idea that mutant forms of p53 act in a dominant-negative manner through C-terminal oligomerization with the wild type.

Antigens, Polyomavirus Transforming↗
PubMed1992

Laparoscopic cholecystectomy. A prospective study of outcome in 100 unselected patients.

OBJECTIVE: To describe the outcome of laparoscopic (percutaneous) cholecystectomy in the management of gallbladder stones. PATIENTS AND METHODS: One hundred unselected consecutive patients referred for cholecystectomy, or admitted as emergencies with complicated gallbladder disease. Ten patients had acute cholecystitis, three had empyema, three had gallstone pancreatitis, and 11 had a history of recent jaundice. Common bile duct stones were dealt with by endoscopic sphincterotomy. OUTCOME MEASURES: Intraoperative and postoperative complications, 30-day mortality rate, duration of hospital stay, and length of postoperative disability. RESULTS: Three patients were excluded and underwent open cholecystectomy. Laparoscopic cholecystectomy was attempted in the remaining 97, and successfully completed in 87; 10 were converted to open cholecystectomy. There were no significant intraoperative complications. Two patients had a postoperative haemorrhage and one had a transient bile leak; none required reoperation. There was one death from myocardial infarction 12 days after operation. Minor complications occurred in 12 patients. Mean operating time was 88 minutes. The average length of hospital stay was 72 hours, and most patients returned to normal activities after seven days. CONCLUSIONS: Laparoscopic cholecystectomy offers an outcome comparable to standard cholecystectomy and is applicable to 90% of patients requiring removal of the gallbladder. Laparoscopic cholecystectomy has significant advantages over open cholecystectomy in terms of reduced postoperative pain and disability.

Adolescent↗
PubMed1992

Collagen fibril structure of normal, aging, and osteoarthritic cartilage.

The collagen architecture in normal, aging, and osteoarthritic articular cartilage was studied optically using a new silver staining technique based on specimens from 50 autopsy cases, four amputated limbs, and six osteoarthritic knees. In the normal articular cartilage, the collagen fibrils in the superficial zone were compactly arranged into layers of decussating flat ribbons mostly parallel to the artificial split lines. The fibrils showed a tendency to condense into vertical arcade columns undergirded by tangential bundles in the intermediate zone. In the deep zone, the fibrils formed a random meshwork with a slight preponderance of vertical fibrils in the perilacunar region. Three types of early degradative lesions involving the collagen network were identified. Type I lesions consisted of focal superficial disruptions related to age and friction. Type II lesions consisted of focal disruptions of tangential fibrils in the intermediate zone leading to cyst formation, probably representing a form of local stress failure. Type III lesions were found in the patella and consisted of marked swelling of the superficial zone, the cause of which was unknown. Lesions of varying severity were seen within each of the three types; the morphological changes of the more severe lesions overlapped with those of clinically overt osteoarthritis.

Adolescent↗
PubMed1992

Field-testing the new DECtalk PC system for medical applications.

Synthesized human speech has now reached a new level of performance. With the introduction of DEC's new DECtalk PC, the small system developer will have a very powerful tool for creative design. It has been our privilege to be involved in the beta-testing of this new device and to add a medical dictionary which covers a wide range of medical terminology. With the inherent board level understanding of speech synthesis and the medical dictionary, it is now possible to provide full digital speech output for all medical files and terms. The application of these tools will cover a wide range of options for the future and allow a new dimension in dealing with the complex user interface experienced in medical practice.

Artificial Intelligence↗
PubMed1992

Laparoscopic anatomy of the cystic artery.

Uncontrolled arterial bleeding during laparoscopic cholecystectomy is a serious problem and may increase the risk of bile duct damage. Therefore, accurate identification of the anatomy of the cystic artery is important. We reviewed the anatomy of the cystic artery and its variations as seen through the video laparoscope. A "normal" cystic artery was found in only 72% of patients. The most important laparoscopically noted variations were doubling of the cystic artery (22%) and an artery that ran inferior to the cystic duct (6%). Small branches of the cystic artery, which we suggest be named Calot's arteries, supply the cystic duct and may cause troublesome bleeding during laparoscopic dissection in the hepatobiliary triangle. A scissor dissection technique was found most useful for identifying the arterial anatomy. Careful identification of arterial anomalies should help to reduce the incidence of bile duct injuries during laparoscopic cholecystectomy.

Arteries↗
PubMed1992

Conserved regulatory elements in the promoter region of the N-CAM gene.

Genomic clones containing 5'-flanking sequences, the first exon, and the entire first intron from the chicken N-CAM gene were characterized by restriction mapping and DNA sequencing. A > 600-bp segment that includes the first exon is very G + C-rich and contains a large proportion of CpG dinucleotides, suggesting that it represents a CpG island. SP-1 and AP-1 consensus elements are present, but no TATA- or CCAAT-like elements were found within 300 bp upstream of the first exon. Comparison of the chicken promoter region sequence with similar regions of the human, rat, and mouse N-CAM genes revealed that some potential regulatory elements including a "purine box" seen in mouse and rat N-CAM genes, one of two homeodomain binding regions seen in mammalian N-CAM genes, and several potential SP-1 sites are not conserved within this region. In contrast, high CpG content, a homeodomain binding sequence, an SP-1 element, an octomer element, and an AP-1 element are conserved in all four genes. The first intron of the chicken gene is 38 kb, substantially smaller than the corresponding intron from mammalian N-CAM genes. Together with previous studies, this work completes the cloning of the chicken N-CAM gene, which contains at least 26 exons distributed over 85 kb.

Animals↗
PubMed1992

The effect of enteral carnitine administration in humans.

We previously determined that the L-carnitine uptake by human duodenal tissue occurs by both active (KT 558 mumol/L) and passive mechanisms. The effects of enteral carnitine was studied in humans. A hamburger meal (345 mumol total carnitine) induced peak jejunal fluid free (unesterified) and short-chain acylcarnitine concentrations (SCAC) of 209 and 130 mumol/L, respectively. Plasma carnitine concentrations and the percent renal reabsorption remained unchanged. By contrast, a pharmacologic dose of free carnitine (25,298 mumol) raised peak intraluminal free and SCAC to 20,660 and 4204 mumol/L. Plasma total carnitine concentrations doubled to 93 mumol/L, and the percent renal reabsorption of free and SCAC declined to 76% and 52%, respectively. In triple-lumen perfusions, 200 mumol carnitine/L was absorbed at 484 nmol.min-1.30 cm-1 jejunum, a rate sufficient for prandial but not pharmacologic assimilation. Our findings indicate that absorption of physiologic and pharmacologic amounts of carnitine occurs predominantly by active transport and passive diffusion, respectively.

Absorption↗
PubMed1992

Inhibition of interleukin 2 receptor expression in normal human T cells by cyclosporine. Demonstration at the mRNA, protein, and functional levels.

In view of the importance of the IL-2 receptors in the expression of antiallograft immunity and the currently existing controversy regarding the effect of CsA on the induction of IL-2 receptors, we explored the effect of cyclosporine on the induction of interleukin-2 receptor alpha and beta in normal human T cells. The effect of CsA on the induction of IL-2 receptors was examined at the levels of mRNA expression (with the aid of the polymerase chain reaction), protein (by SDS-PAGE analysis of chemically crosslinked 125I-IL-2 membrane protein complexes and by FACS), and function (by Scatchard analysis of 125I-IL-2 binding to T cells). The T cells were signaled with sn-1,2-dioctanoylglycerol and ionomycin or with crosslinked anti-CD3 and anti-CD2 mAbs. Our experimental design revealed that (A) CsA inhibits the induction of IL-2 receptor alpha and beta in normal human T cells, (B) the inhibitory activity is realized by a direct effect on T cells, and (C) the inhibitory activity is detectable at the pretranslational level--CsA significantly reduced the induction of mRNA encoding IL-2 receptor alpha and IL-2 receptor beta. These observations together persuasively demonstrate the ability of CsA to interrupt the emergence of IL-2 receptors on the surface of normal human T cells.

Antibodies, Monoclonal↗
PubMed1992

Characterization and subcellular localization of debranching enzyme and endoamylase from leaves of sugar beet.

Sugar beet leaves (Beta vulgaris L.) contained up to five endoamylases, two exoamylases, and a single debranching enzyme. Four of the endoamylases and the debranching enzyme were present in the chloroplast. The chloroplastic starch-debranching enzyme and an apoplastic endoamylase were copurified from mature leaves of sugar beet by 35 to 50% ammonium sulfate precipitation and chromatography on diethylaminoethyl-Sephacryl, beta-cyclodextrin Sepharose 6B, and Sephadex G-150. The debranching enzyme, which was purified to homogeneity, had a molecular mass of 100 kilodaltons and a pH optimum of 5.5. It showed a high activity with pullulan as a substrate, low activity with soluble starch and amylopectin, and no activity with native starch grains isolated from sugar beet leaves. The endoamylase, which was partially purified, had a molecular mass of 43,000 kilodaltons, a pH optimum of 6.5, required calcium for activity and thermal stability, and showed an ability to hydrolyze native starch grains.

Journal Article↗
PubMed1992

Evidence for circadian regulation of starch and sucrose synthesis in sugar beet leaves.

Starch accumulation and sucrose synthesis and export were measured in leaves of sugar beet (Beta vulgaris L.) during a period of prolonged irradiance in which illumination was extended beyond the usual 14-hour day period. During much of the 14-hour day period, approximately 50% of the newly fixed carbon was distributed to sucrose, about 40% to starch, and less than 10% to hexose. Beginning about 2 hours before the end of the usual light period, the portion of newly fixed carbon allocated to sucrose gradually increased, and correspondingly less carbon went to starch. By the time the transition ended, about 4 hours into the extension of the light period, nearly 90% of newly fixed carbon was incorporated into sucrose and little or none into starch. Most of the additional sucrose was exported. Gradual cessation of starch accumulation was not the result of a futile cycle of simultaneous starch synthesis and degradation. Neither was it the result of a decrease in the extractable activity of adenosine diphosphoglucose pyrophosphorylase or phosphoglucose isomerase, enzymes important in starch synthesis. Nor was there a notable change in control metabolites considered to be important in regulating starch synthesis. Starch accumulation appeared to decrease markedly because of an endogenous circadian shift in carbon allocation, which occurred in preparation for the usual night period and which diverted carbon from the chloroplast to the cytosol and sucrose synthesis.

Journal Article↗