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Biomedical subjects

L Fan

Publications and source records attributed to L Fan.

At least 109 records · Page 6Linked to original sources
PubMed1998

[Data cleaning in the 1995-1996 national smoking prevalence survey].

The authors introduced the procedure of data cleaning in the 1995-1996 national smoking prevalence survey, and the objectives, principles, procedures, quality evaluation and points for attention of data cleaning were summarized. Data cleaning must be carried out from the smallest investigative unit. The logical relationship among variables must be fully considered for the revision of incorrect values. In dealing with miss values, their roles in the statistical analyses must be evaluated. Comparing the differences in some important variables before and after cleaning is a useful method for assessing whether the representativeness of the data has been changed during the cleaning process.

China↗
PubMed1998

[Preparation of novel macroporous silica-based amide-polymer-bonded packing and its application to the separation of proteins].

A novel macroporous silica-based amide-polymer-bonded packing for protein separations in HPLC is described. The macroporous silica support was bonded with diethoxymethyl vinyl silane and then copolymerized with methylacrylamide and divinylbenzene to produce a tailored stationary phase with high resolution and inertness. The repeatability of packing preparation is good. They were characterized through the application of a standard protein mixture of pepsin, glucose oxidase, bean trypsinogen inhibitor and ribonuclease. The time for elution of these proteins is less than 12 minutes. It is suggested that the macroporous silica-based amide-polymer-bonded packing can be used to quickly separate biopolymer. This packing is a better alternative for the biopolymer separation.

Chromatography, High Pressure Liquid↗
PubMed1998

[Head trauma and brain auditory evoked potentials].

The study investigated brain auditory evoked potentials (BAEP) in patients complaining auditory disturbances after head trauma. The results showed that the incidence of hearing loses was 57.5% and the rate of abnormality of BAEP is 33.75%. The types of the abnormalities of BAEP varied and were related with the position and severity of the head trauma. The types of the abnormalities manifested as loses of I-II waves, prolongation of V latency and I-V interlatency.

Adolescent↗
PubMed1998

[Extra-anatomy axillary-femoral or femoro-femoral bypass grafting for the treatment of aorta-iliac occlusive disease].

OBJECTIVE: To study the result of extra-anatomy axillary-femoral or femoro-femoral bypass grafting which was performed to treat aorta-iliac arterial occlusive disease. METHOD: From 1978 through 1997, 32 patients with aorta-iliac occlusive disease underwent extra-anatomy axillary-femoral or femoro-femoral bypass grafting at our hospital. Eighteen patients with aorta or bilateral iliac artery occlusive lesion underwent axillary-femoral artery bypass, including axillary-bifemoral artery bypass (2 patients). Fourteen patients with one side iliac arterial occlusive lesion received femoro-femoral bypass grafting. In who had had axillary-femoral artery bypass 18 patients, 8 received, pure silk prosthesis, and 10 Gore-Tex prosthesis. In femoro-femoral arterial bypass, pure silk prosthesis was given to 8 patients, saphenous vein to one, and Gore-Tex prosthesis to 7. RESULT: Follow-up for 5 years, a patency rate of 78% was achieved in femoro-femoral artery bypass, in which no different patency rate was found between pure silk prosthesis and Gore-Tex prosthesis. In axillary-femoral bypass, eight pure silk prostheses were occluded after 5-year follow-up. One of 10 Gore-Tex prostheses was occluded, and false aneurysm in groin was found in another patient. CONCLUSION: This operation is easy and safe, it has less damage and no abdominal complication. The recovery of the patient is quick. Pure silk prostheses are only used in short segment femoro-femoral bypass grafting.

Adult↗
PubMed1997

Multiple sorting signals determine apical localization of a nonglycosylated integral membrane protein.

In polarized cells, newly synthesized proteins are sorted in the trans-Golgi network and from there delivered to either the apical or basolateral membranes. Madin-Darby canine kidney (MDCK) cells have been widely used as a model system to study sorting determinants to the apical and basolateral surfaces. Whereas sorting signals for basolateral transmembrane proteins seem to reside in their cytoplasmic domains, apical determinants appear to reside in the N-glycans of secretory proteins or in the glycolipid tails of glycosylphosphatidylinositol-linked proteins. We show in this study that a surface-expressed form of CD3-epsilon, a nonglycosylated type I membrane protein, is exclusively targeted to the apical membrane in MDCK cells by a glycolipid-independent transport pathway. Deletion of the cytoplasmic tail does not affect its distribution, whereas deletion of the transmembrane domain results in secretion from both surfaces although still predominantly through the apical membrane. The transmembrane domain of CD3-epsilon appended to rat growth hormone, a secretory protein that lacks apical and basolateral determinants, promotes basolateral localization of the chimeric protein. However, a growth hormone chimera containing both the transmembrane and cytoplasmic domains of CD3-epsilon resulted in localization to the apical and basolateral membranes. These results suggest there are multiple determinants in CD3-epsilon that affect its distribution in polarized MDCK cells. Whereas the transmembrane domain contains a basolateral determinant, the ectodomain and the cytoplasmic domain contain apical determinants.

Animals↗
PubMed1997

Activation of CPP32-like caspases contributes to neuronal apoptosis and neurological dysfunction after traumatic brain injury.

We examined the temporal profile of apoptosis after fluid percussion-induced traumatic brain injury (TBI) in rats and investigated the potential pathophysiological role of caspase-3-like proteases in this process. DNA fragmentation was observed in samples from injured cortex and hippocampus, but not from contralateral tissue, beginning 4 hr after TBI and continuing for at least 3 d. Double labeling of brain with terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) and an antibody directed to neuronal nuclear protein identified apoptotic neurons with high frequency in both traumatized rat cortex and hippocampus. Cytosolic extracts from injured cortex and hippocampus, but not from contralateral or control tissue, induced internucleosomal DNA fragmentation in isolated nuclei with temporal profiles consistent with those of DNA fragmentation observed in vivo. Caspase-3 mRNA levels, estimated by semiquantitative RT-PCR, were elevated fivefold in ipsilateral cortex and twofold in hippocampus by 24 hr after TBI. Caspase-1 mRNA content also was increased after trauma, but to a lesser extent in cortex. Increased caspase-3-like, but not caspase-1-like, enzymatic activity was found in cytosolic extracts from injured cortex. Intracerebroventricular administration of z-DEVD-fmk-a specific tetrapeptide inhibitor of caspase-3-before and after injury markedly reduced post-traumatic apoptosis, as demonstrated by DNA electrophoresis and TUNEL staining, and significantly improved neurological recovery. Together, these results implicate caspase-3-like proteases in neuronal apoptosis induced by TBI and suggest that the blockade of such caspases can reduce post-traumatic apoptosis and associated neurological dysfunction.

Animals↗
PubMed1997

Caveolin and MAL, two protein components of internal detergent-insoluble membranes, are in distinct lipid microenvironments in MDCK cells.

The MAL proteolipid and caveolin have been identified as components of internal detergent-insoluble membrane microdomains enriched in glycolipids and cholesterol. We have addressed the study of the glycolipid-enriched membranes in cells expressing endogenously only either MAL (Jurkat T cells) or caveolin (epithelial A498 cells) and in polarized MDCK cells which express both proteins simultaneously. Subcellular fractionation by centrifugation to equilibrium in sucrose gradients of Triton X-100 cell extracts from Jurkat and A498 cells revealed that MAL and caveolin are incorporated in detergent-insoluble buoyant membranes independently of the expression of each other and indicated the existence in these cells of insoluble membrane microdomains with either MAL or caveolin. Immunofluorescence analysis in MDCK cells indicated that both MAL and caveolin were located in the Golgi region, whereas caveolin was found in addition at the cell surface. Biochemical analysis in these cells revealed the existence of distinct membrane microenvironments differentially susceptible to detergent solubilization containing either internal MAL or internal plus surface caveolin. The observed heterogeneity within the internal glycolipid-enriched membrane fraction suggests the existence of distinct specialized lipid microenvironments in MDCK cells.

Animals↗
PubMed1997

The MAL proteolipid is a component of the detergent-insoluble membrane subdomains of human T-lymphocytes.

The human mal gene, identified during a search for cDNAs selectively expressed during T-cell development, encodes a highly hydrophobic protein belonging to a group of proteins, termed proteolipids, characterized by their unusual property of being soluble in organic solvents used to extract cell lipids. To study the localization of the MAL protein we have prepared stable transfectants expressing the MAL protein tagged with a c-myc epitope (MAL/c-myc) using human epithelial A-498 cells. Immunofluorescence analysis suggested that MAL/c-myc is localized mainly to cholesterol-enriched structures with a post-Golgi location and, at low levels, in early endosomes. Moreover, extraction of A-498 cell membranes with Triton X-100 (TX100) and fractionation by centrifugation to equilibrium in sucrose gradients demonstrated the presence of MAL/c-myc in the detergent-insoluble buoyant fraction, known to be enriched in glycolipids and cholesterol. To compare the behaviour of MAL in T-cells with that in epithelial A-498 cells, we prepared stably transfected cells expressing MAL/c-myc using human Jurkat T-cells. When TX100 extracts from Jurkat cells were subjected to centrifugation to equilibrium in sucrose gradients we found MAL exclusively in the floating fractions, together with molecules characteristic of the T-cell insoluble complexes, such as the tyrosine kinase p56lck, the glycosylphosphatidylinositol-anchored protein CD59 and the ganglioside GM1. These results, taken together, indicate that the MAL proteolipid is a component of the detergent-resistant membrane microdomains present in T-lymphocytes, and suggest that MAL might play a role in modulating the function of these microdomains during T-cell differentiation.

Animals↗
PubMed1997

Modifications in the B10 and B26-30 regions of the B chain of human insulin alter affinity for the human IGF-I receptor more than for the insulin receptor.

Inversion of the natural sequence of the B chain of human insulin (HI) from ProB28LysB29 to LysB28ProB29 generates an insulin analogue with reduced tendency to self-associate. Since this substitution increases the homology of insulin to insulin-like growth factor-I (IGF-I), we have examined the affinity of a series of insulin analogues with the general modified structure XaaB28ProB29 HI for binding to both human placental insulin and IGF-I receptors. The XaaB28ProB29 HI series is approximately equipotent to HI in binding to the insulin receptor with the exception of when Xaa = Phe, Trp, Leu, Ile, and Gly (40-60% relative to HI). Substitution with basic residues in the B28 position increased the relative affinity to the IGF-I receptor approximately 1.5-2-fold (ArgB28ProB29 > OrnB28ProB29 = LysB28ProB29). Substitution with acidic residues reduced relative affinity for the IGF-I receptor approximately 2-fold (CyaB28ProB29 = GluB28ProB29 > AspB28ProB29). Combination of AspB10 substitution in conjunction with a modification in the B28-29 position (e.g. AspB10LysB28ProB29 HI) showed an additional 2-fold selective increase in affinity for the IGF-I receptor, suggesting that these two effects are additive. Addition of Arg residues at B31-32, on the backbone of either HI or AspB10 HI, increased affinity for the IGF-I receptor 10 and 28 fold, respectively, compared to HI, confirming the significance of enhanced positive charge at the C-terminal end of the insulin B-chain in increasing selectivity for the IGF-I receptor. This relative increase in IGF-I receptor affinity correlated largely, but not completely, with enhanced growth promoting activity in human mammary epithelial cells. In the case of LysB28ProB29 HI, growth activity correlated with dissociation kinetics from the insulin receptor which were shown to be identical with those of human insulin.

Amino Acid Sequence↗
PubMed1997

Estimation of total collagen and types I and III collagen in canine rotator cuff tendons.

The collagen composition of the supraspinatus, infraspinatus, and subscapularis tendons, which form part of the rotator cuff of the shoulder, was determined. Tendons were obtained from adult, male beagle dogs and total collagen was estimated by measurement of hydroxyproline. There was little variation in collagen content among the three major cuff tendons and the quantity approximated that cited in the literature for other tendons. However, the collagen content in the insertion zone of the supraspinatus tendon was significantly higher than in the tendon proper. NaCl fractionation of supraspinatus collagen indicated that type I was the predominant collagen but significant amounts of type III and possibly some type II and type V were also present. Interestingly, there appeared to be more type III collagen in the insertion zone than in the tendon proper, cyanogen bromide digestion and peptide mapping confirmed this finding. The differential collagen composition of the supraspinatus tendon may contribute to the high incidence of tear that is associated with this rotator cuff tendon.

Animals↗
PubMed1997

Laparoscopic fundoplication to enhance pulmonary function in children with severe reactive airway disease and gastroesophageal reflux disease.

BACKGROUND: The relationship between severe reactive airway disease (RAD) and gastroesophageal reflux disease (GERD) has been noted but the relationship is poorly understood. This study reports our experience with laparoscopic fundoplication and its effect on the pulmonary status of children with severe steroid-dependent reactive airway disease. METHODS: Fifty-six patients with severe steroid-dependent RAD and medically refractory GERD underwent laparoscopic Nissen fundoplications. Mean age was 7 years and mean weight was 20 kg. All patients had the procedure completed successfully laparoscopically with an average operative time of 62 min. Average hospital stay was 1.6 days. RESULTS: Forty-eight of 56 patients noted significant improvement in their respiratory symptoms in the first week. Fifty of 56 patients have been weaned off their oral steroids and four others have had a greater than 50% decrease in their dose. Sixteen patients had a documented increase in their FEV1 in the initial postoperative period (avg. 26%). CONCLUSION: Patients with steroid-dependent RAD and GERD refractory to medical management show improvement in their respiratory status following fundoplication and the majority can be weaned off of their oral steroids. Laparoscopic techniques allow this procedure to be performed safely even in this high-risk group of patients.

Adolescent↗
PubMed1997

Antisense suppression of phospholipase D alpha retards abscisic acid- and ethylene-promoted senescence of postharvest Arabidopsis leaves.

Membrane disruption has been proposed to be a key event in plant senescence, and phospholipase D (PLD; EC 3.1.4.4) has been thought to play an important role in membrane deterioration. We recently cloned and biochemically characterized three different PLDs from Arabidopsis. In this study, we investigated the role of the most prevalent phospholipid-hydrolyzing enzyme, PLD alpha, in membrane degradation and senescence in Arabidopsis. The expression of PLD alpha was suppressed by introducing a PLD alpha antisense cDNA fragment into Arabidopsis. When incubated with abscisic acid and ethylene, leaves detached from the PLD alpha-deficient transgenic plants showed a slower rate of senescence than did those from wild-type and transgenic control plants. The retardation of senescence was demonstrated by delayed leaf yellowing, lower ion leakage, greater photosynthetic activity, and higher content of chlorophyll and phospholipids in the PLD alpha antisense leaves than in those of the wild type. Treatment of detached leaves with abscisic acid and ethylene stimulated PLD alpha expression, as indicated by increases in PLD alpha mRNA, protein, and activity. In the absence of abscisic acid and ethylene, however, detached leaves from the PLD alpha-deficient and wild-type plants showed a similar rate of senescence. In addition, the suppression of PLD alpha did not alter natural plant growth and development. These data suggest that PLD alpha is an important mediator in phytohormone-promoted senescence in detached leaves but is not a direct promoter of natural senescence. The physiological relevance of these findings is discussed.

Abscisic Acid↗
PubMed1997

[Application of the myringoscope and myringophotography in forensice medical identification].

In analysis of tympanitio membrane injury, we have compared conventional otoscope with myringoscope and found that the myringoscope has an advantage over the conventional otoscope. The myringoscope can show the whole tympanitic membrane, the positions, shapes and characteristics of tympanitic membrane injuries more clearly. The pictures of myringophotography could be preserved and offered to court as an important forensic medical evidence.

Adult↗
PubMed1997

[cDNA cloning, sequencing and expression of recombinant human prorelaxin].

In order to accelerate the development of biological recombinant human prorelaxin in our country, direct cloning of human prorelaxin gene from freshly prepared corpus luteum of Chinese woman by RT-PCR method was conducted. Isolated prorelaxin gene contains B, A chains and connective peptide. The amplified products were cloned and confirmed by DNA sequencing using Sanger Dideoxy method. It was subcloned into LKB2, a prokaryotic expression vector offering promoter LacI control, and highly expressed in E. coli. The results suggest that the PCR amplified DNA fragment shared identical sequence with known prorelaxin gene reported abroad. The SDS-PAGE analysis revealed that the expressed protein accounted for about 30% of the total cell protein, its MW was approximately 20 kD and conformed soluble protein.

Cloning, Molecular↗
PubMed1997

[Analysis of hexamethylene bisacetamide in biological fluids and tissues by RP-HPLC].

This paper describes the analysis of anticancer drug hexamethylene bisacetamide (HMBA) in biological fluids and tissues by RP-HPLC. The samples of plasmas, urine and tissues from cancer mice and rabbits were first used with methanol for pretreatment to remove protein impurity, then analyzed by RP-HPLC on an ODS column. The mobile phase was methanol/water (70/30, V/V), UV detection is employed at 210 nm. 153 samples were analyzed and good results were obtained. The recoveries of 93.3%-104% with a relative standard deviation of 0.04%. The regression equation is: Y = 0.32X - 1.07, with a linear correlation coefficient of 0.998 and the linear range of HMBA is 0 to 1000 mg/L. A sample analysis can be completed within 13 minutes. This method could be satisfactorily applied not only for the analysis of HMBA but probably also for the analysis of other drugs in biological fluids and tissues.

Acetamides↗
PubMed1997

[Association of pregnancy induced hypertension with human leucocyte antigen system].

OBJECTIVE: To examine whether pregnancy induced hypertension (PIH) is correlated with a polymorphism of human leucocyte antigen (HLA)-DRB1 in the Shanghai population. METHODS: We determined the HLA-DRB1 types of 17 PIH families and 14 normotension families by DNA typing utilizing the polymerase chain reaction (PCR) and hybridization of Dig-labeled sequence specific oligonucleotide (PCR-SSO). RESULTS: The antigens frequency and feto-material sharing of HLA-DR4 in PIH were increased and relative to that of the controls, and furthermore the 0405 allele occurred more often in PLH patients. CONCLUSION: These results suggest that a PIH susceptibility gene is associated with HLA-DRB1 0405. We therefore propose the following working hypothesis; 0405 allele is presumably due to linkage disequilibrium or the possibility that it acts directly as an immune response gene; PIH is correlated with DR4 compatibility between PIH mother and fetus which leads to failure of the mother's nonresponsiveness to fetal antigen. Lack of blocking factor increases the risk for PIH.

Adult↗