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Biomedical subjects

G Cheng

Publications and source records attributed to G Cheng.

At least 163 records · Page 9Linked to original sources
PubMed1997

[Determination of docosyl ferulate in extract of Pygeum africanton Hook. by high performance liquid chromatography (HPLC)].

This paper reports a method for the determination of docosyl ferulate in the extract of bark of pygeum africanum Hook. by HPLC. After the sample was pretreated, the docosyl ferulate was well separated and determined on a Spherisorb C18 column (250 x 4.6mm, 5microm) using a mobile phase of methanol with a flow rate of 1mL/min. The column temperature was selected at 40 degrees C to avoid tailing of peak. UV detection was performed at 326nm. In order to confirm the docosyl ferulate separated from sample, the peak apex at 10.4 minute was scanned from 195nm to 360nm by photodiode array detector. Its spectrum showed the maxium absorption peak at 240nm and 326nm corresponding with the spectrum of docosyl ferulate. The linear correlation was observed from the 10mg/L to 100mg/L of docosyl ferulate (r = 0.9995). The average recovery was 98.4% +/- 1.98%. Three batches of sample were determined.

Chromatography, High Pressure Liquid↗
PubMed1997

[Study on the interaction of metal ion in active center of superoxide dismutase with cobalt chloride by visible spectroscopy].

The direct interaction of metal ion in active center of copper-zinc superoxide dismutase (Cu2Zn2SOD) with inorganic cobalt chloride (CoCl2) in buffer has been first studied by visible spectroscopy. The effects of increasing amounts of CoCl2, changing pH,different acid salt and equilibrium time on the interaction have been discussed. It was found that the Co(II) of CoCl2 makes an exchanging interaction with Zn(II) in Cu2Zn2SOD and thus the partial Cu2Co2SOD is formed.

Buffers↗
PubMed1997

Expression of HBsAg gene in transgenic goats under direction of bovine alpha-S1 casein control sequence.

An expressive construct combining hepatitis B surface antigen gene and bovine alpha-S1 casein control sequence (a 16-kb fragment), lambda 106, was made successfully using DNA recombination technology. The construct was then introduced into fertilized goat eggs with a transgenic technique. As the eggs developed into adults which, in turn, began to secrete milk after parturition, ELISA assay demonstrated HBsAg in the milk, thus showing successful expression of the construct in the mammary gland of the G0 transgenic goats and the secretion of the expression product into the milk.

Animals↗
PubMed1997

[Relative contribution of ageing and menopause to the changes of lumbar bone density in 1,400 Beijing women].

OBJECTIVE: To study the pattern of bone mass changes in women's lumbar spine and obtain evidence to guide the prevention of postmenopausal osteoporosis. METHOD: Bone mineral content (BMC) and bone mineral density (BMD) of lumbar 1-4 in 1 400 Beijing women aged 20-85, were measured by dual energy X-ray absorptiometry. RESULTS: (1) Both BMC and BMD increased after age 20, reached the peak at the age of 30, and decreased significantly after the age of 50; (2) There was no significant change of BMC and BMD after the age of 25 in premenopausal women. Bone loss accelerated in the first 10 years after menopause. Women who experienced menopause early had lower bone mass. (3) The prevalence of osteoporosis in 1 121 postmenopausal women was 17.40%. CONCLUSION: Significant bone mass loss of lumbar spine occurs during the first decade following menopause, which is the key period for preventing osteoporosis.

Adult↗
PubMed1997

[Changes of NMDA receptor gene expression in infection brain injury induced by Bordetella pertussis in rats].

N-methyl-D-aspartate receptors (NMDAR) in cerebral cortexes of rat brain injury induced by Bordetella pertussis (Bp) were measured by methods of Northern blot analysis and [3H] MK-801 radioligand-receptor binding to study changes and effects of NMDAR1 of gene expression in the infection brain injury. The affinity (Kd) of NMDAR in Bp group was significantly decreased [30.5 +/- 3.0 nmol.L-1 (Bp), 43.1 +/- 4.2 nmol.L-1 (NS), P < 0.05], but expression of NMDAR1 mRNA and binding site density (Bmax) of NMDAR observed no significant differences between the experimental and the control group (P > 0.05), respectively. The results suggest that NMDAR1 was activated with high affinity functionally, but no changes in binding site density and transcriptional expression of NMDAR1 occured in the infection brain injury.

Animals↗
PubMed1996

The alpha(1,3)fucosyltransferase Fuc-TVII controls leukocyte trafficking through an essential role in L-, E-, and P-selectin ligand biosynthesis.

alpha(1,3)Fucosylated oligosaccharides represent components of leukocyte counterreceptors for E- and P-selectins and of L-selectin ligands expressed by lymph node high endothelial venules (HEV). The identity of the alpha(1,3)fucosyltransferase(s) required for their expression has been uncertain, as has a requirement for alpha(1,3)fucosylation in HEV L-selectin ligand activity. We demonstrate here that mice deficient in alpha(1,3) fucosyltransferase Fuc-TVII exhibit a leukocyte adhesion deficiency characterized by absent leukocyte E- and P-selectin ligand activity and deficient HEV L-selectin ligand activity. Selectin ligand deficiency is distinguished by blood leukocytosis, impaired leukocyte extravasation in inflammation, and faulty lymphocyte homing. These observations demonstrate an essential role for Fuc-TVII in E-, P-, and L-selectin ligand biosynthesis and imply that this locus can control leukocyte trafficking in health and disease.

Animals↗
PubMed1996

The exit from G(0) into the cell cycle requires and is controlled by sarco(endo)plasmic reticulum Ca2+ pump.

The intracellular calcium pump sarco(endo)plasmic reticulum Ca2+ (SERCA) is responsible for the formation of the Ca2+ gradient across the endoplasmic reticulum membrane, and this gradient is used to generate the Ca2- signal during agonist-stimulated cell growth. In the present study, the role of SERCA in both cell cycle and growth control was investigated using cultured rat aortic endothelial cells (RAEC). Using a novel DNA transfection approach, cell lines were established that showed varying degree of SERCA activity through the down-regulation of the endogenous SERCA gene (B. F. Liu, X. Xu, R. Fridman, S. Muallem, and T. H. Kuo, J. Biol. Chem. 271, 1--9, 1996). Cell proliferation studies indicated that the lower SERCA expressing cells exhibited a slower growth pattern without altering the doubling time which was similar for both parental and transfected RAEC lines. G1 to S phase transition was prolonged with a smaller proportion of cells entering DNA synthesis as indicated by thymidine incorporation assay. Comparison of transfected cell lines indicated a tight coupling of SERCA activity and the length of the G1 period. Down-regulation of SERCA gene expression was accompanied by increased mRNA levels of p21 (WAF1/CIP1), a universal cell cycle inhibitor. The delay in G1 to S progression also coincided with the up-regulation of p53 mRNA and underphosphorylation of the retinoblastoma protein. This study suggests that Ca2+ metabolism in the agonist mobilizable pool controls the cell cycle through the regulation of genes operating in the critical G1 to S checkpoint.

Animals↗
PubMed1996

TANK, a co-inducer with TRAF2 of TNF- and CD 40L-mediated NF-kappaB activation.

We describe a new signal mediator of NF-kappaB activation, TANK, that acts in a pathway common to two surface receptors CD40 and TNFR II. TRAF family members interact directly with these receptors. Using the yeast two-hybrid system, TANK was identified as an intracellular protein without previous homologs that interacts with all three known TRAF family members. In cotransfection experiments, TANK and TRAF2 activate NF-kappaB synergistically, requiring both the amino-terminal portion of TANK and the ring finger domain of TRAF2. TANK has a negatively acting carboxyl terminus and is constitutively inactive, but TRAF2 binding overcomes the internal inhibitory influence. We propose that ligand binding to CD40 or TNFR II leads to the formation of a TRAF2/TANK complex, mediating NF-kappaB activation.

Adaptor Proteins, Signal Transducing↗
PubMed1996

Establishing a reliable visual function test and applying it to screening optic nerve disease in onchocercal communities.

The computer Controlled Video Perimetry (CCVP) is a computer screening test for detecting visual function loss caused by onchocerciasis, glaucoma, etc. Installed on portable computers, the CCVP has been shown to be high acceptability in field community investigation. However, it is regarded to be difficult in obtaining reliable results from portable computer screening tests because of human behavioural variants and the lack of standard testing environment. In this paper, we propose an architecture for implementing a more reliable CCVP system. In particular, a self-organising neural network is applied to manage measurement noise caused by behavioural factors. A control unit is introduced to manage the overall behaviour of the system. The integrated test system has been used to screen optic nerve disease in onchocercal communities of rural Nigeria and the experimental results obtained from a large number of test records are very encouraging: reliable results from volatile test environments may be obtained using the proposed method.

Artifacts↗
PubMed1996

Salsalate, morphine, and postoperative ileus.

BACKGROUND: Previously, we demonstrated that ketorolac, a nonsteroidal antiinflammatory drug (NSAID), prevented postoperative small bowel ileus in a rodent model. The aim of this study was to evaluate the effect of salsalate, an NSAID without antiplatelet effect, on postoperative ileus alone or in combination with morphine. METHODS: Forty-eight rats underwent placement of duodenal catheters and were then randomly assigned to one of eight groups (n = 6). Four groups had standardized laparotomy following drug administration, whereas 4 groups underwent the same treatment without laparotomy: control and morphine animals received 0.1 mL alcohol via the catheter, whereas salsalate and salsalate-plus-morphine animals received salsalate (15 mg/kg) dissolved in 0.1 mL alcohol. The animals also received 0.5 mg/kg morphine (morphine and salsalate plus morphine) or the same volume of saline (control and salsalate) subcutaneously. Transit was measured following the injection of a nonabsorbed marker via the duodenal catheter and is defined as the geometric center (GC) of distribution. An additional 20 rats had serosal electrodes placed on the jejunum, and were assigned to one of four treatment groups (control, salsalate, morphine, and salsalate plus morphine; n = 5 each group). Myoelectric activity was recorded until the reappearance of the migrating myoelectric complex (MMC) following laparotomy. RESULTS: Laparotomy and morphine independently reduced small bowel transit (P = 0.0006 and 0.006, respectively, by three-way analysis of variance [ANOVA]; GC 4.3 +/- 0.2 control versus 2.2 +/- 0.3 laparotomy versus 3.6 +/- 0.4 morphine), but morphine did not further worsen postoperative transit (GC 2.4 +/- 0.4; P = 0.42). Although salsalate did not alter baseline transit, pretreatment improved postoperative transit (P = 0.0002; GC 3.6 +/- 0.4). This effect was lost with the addition of morphine (GC 2.7 +/- 0.2; P = 0.21). The MMCs returned earlier after laparotomy in salsalate-pretreated rats (63 +/- 18 minutes salsalate versus 160 +/- 12 minutes laparotomy; P < 0.01, one-way ANOVA). However, this effect was also lost in animals receiving morphine (106 +/- 16 min; P > 0.05). CONCLUSION: Salsalate improves postoperative small bowel motility in a rodent model; however, this effect is masked by morphine.

Animals↗
PubMed1996

Targeted disruption of TRAF3 leads to postnatal lethality and defective T-dependent immune responses.

TRAF3 was found as a protein that binds to the cytoplasmic tail of CD40 but is part of a family of proteins with common structure and activity. To clarify the physiological roles of TRAF3, we introduced a TRAF3 null mutation in mice through homologous recombination. TRAF3-deficient mice appear normal at birth but become progressively runted, correlating with progressive hypoglycemia and depletion of peripheral white cells. The mutant mice die by 10 days of age. Fetal liver cells from TRAF3-deficient embryos can reconstitute all hematopoietic lineages in lethally irradiated mice. However, these reconstituted mice are impaired in their immune responses to T-dependent antigen, and their T cells are functionally defective. These findings indicate that TRAF3 is required for postnatal development and for a competent immune system.

Animals↗
PubMed1996

The effects of a self-educating blood component request form and enforcements of transfusion guidelines on FFP and platelet usage. Queen Mary Hospital, Hong Kong. British Committee for Standards in Hematology (BCSH).

Despite establishment of transfusion guidelines and feedback intervention, FFP and platelet transfusion were still inappropriate in many clinical situations at our hospital. Many physicians never read or referred to the guidelines when they were ordering FFP and platelet transfusion. A new blood component request form with the guidelines printed on it was designed to facilitate physician education and enforcement of these transfusion guidelines. The form was well accepted by junior house staff and inappropriate transfusion was significantly reduced.

Attitude of Health Personnel↗
PubMed1996

Provision of an out-of-hours blood banking service at a satellite hospital without blood bank staff.

With limited health care resources and financial constraints, many hospitals have to reduce their service. Computer crossmatching has been accepted as a safe crossmatching procedure for patients without clinically significant alloantibodies. We report here a novel way of providing an out-of-hours blood banking service at a satellite hospital. The system is easy to introduce and can provide a safe transfusion service to small hospitals without stationing blood banking staff at these hospitals after regular working hours.

Blood Banks↗
PubMed1996

The 'market' for medical and health information in transition: the case of the Hong Kong Hospital Authority libraries.

The last few years have been a period of transition not only for hospitals and their governance but also for post-graduate medical education in Hong Kong. Both trends have a direct impact on the information market place. This article starts by studying the provision of medical and health-related information in Hong Kong. The two university medical and dental libraries, together with the hospital and health sciences libraries in government hospitals and the Department of Health, house the major collections on medicine and health care. The demand for medical and health care information is increasingly felt with the takeover of 39 hospitals by the statutory Hong Kong Hospital Authority in 1991. The major problems and issues in planning for library information services are the historically uneven development of libraries, discrepancies in funding, the changes in organizational and management structure, and the competition with higher development priorities within the organization. In view of current technology and the availability of rich external resources, the adopted strategies tend towards the formation of 10 library service networks, development of integrated library information systems on the Health Authority-wide area network, and the devolution of management responsibilities. The future challenges in store for the information professional are examined.

Community Networks↗
PubMed1996

From maximum surgical blood ordering schedule to unlimited computer crossmatching: evolution of blood transfusion for surgical patients at a tertiary hospital in Hong Kong.

The maximum surgical blood ordering schedule (MSBOS) was developed to permit efficient use of blood stocks and reduce blood wastage due to outdating. Success of the MSBOS required full cooperation between surgeons, anaesthetists, blood bankers and house officers. However, clinical staff sometimes disregarded the system or distrusted the ability of the laboratory to provide blood in an emergency. This led to frustration and wastage of laboratory staff effort. We developed a computer crossmatch system that could overcome the shortcomings of the MSBOS. The advantages of this system are reported.

Antibodies↗