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Biomedical subjects

F Lu

Publications and source records attributed to F Lu.

At least 55 records · Page 3Linked to original sources
PubMed2001

Experimental study on the effect of perfluorodecalin on rabbit corneas.

PURPOSE: To study the effects of perfluorodecalin on the cornea of the rabbit eyes. METHODS: Perfluorodecalin (0.05 ml/each) was injected into the anterior chambers of eighteen rabbit eyes. Corneal morphology and endothelial cells were monitored clinically by slit-lamp biomicroscope and specular microscope for 26 weeks. Animals were sacrificed in 1st, 2nd, 4th, 10th, 16th, 22nd, and 26th week after injection, respectively, and the corneas were examined under the light microscope. RESULTS: Perfluorodecalin droplets looking like "fish eggs" were found at about 1/4-1/2 of the corneal height in the inferior anterior chamber. Corneal opacification on the area contacted with perfluorodecalin was observed in five eyes five weeks after injection, and all in the 22nd week. Mutton fat KPs in one eye were seen in the 6th week firstly, and in all eyes in the 7th week. Corneal pannus formation in one eye was present in the 4th week, two eyes in the 5th week and three eyes in the 6th week. Retrocorneal fibrous membrane in one eye was detected at the 6th week and 3 eyes at the 7th week respectively. After injection of perfluorodecalin, endothelial cell density was significantly decreased (2,789 +/- 192 vs. 2,341 +/- 658, P < 0.01) and corneal thickness was increased. CONCLUSIONS: Perfluorodecalin injected into anterior chamber can lead to corneal damage and inflammatory reaction.

Animals↗
PubMed2000

An epidemiological and ecological study of human alveolar echinococcosis transmission in south Gansu, China.

Human alveolar echinococcosis (AE) is usually a rare, highly pathogenic zoonotic disease, transmitted across the northern hemisphere between fox and rodent hosts. In China the first cases were described in 1965; however very few epidemiological studies have been undertaken since. Following identification in 1991 of a serious focus of human AE in south Gansu province, detailed village-based community and ecological studies were carried out between 1994 and 1997. Hepatic ultrasound mass screening with serological testing (five tests) identified 84/2482 new AE cases (3%). An overall prevalence of 4.1% (135/3331) was recorded for the area when previous cases were also included. Based on a seropositive result only, without an ultrasound scan indication, no additional AE cases were identified. Of the evolutive AE cases, 96% were seropositive in at least one test, while up 15-20% of individuals who exhibited hepatic calcified lesions and 12-15% exhibiting hepatic nodular lesions were seropositive for specific Em2 or Em18 antibodies. Village (n=31) human AE prevalence rates varied from 0 to 15.8%. Questionnaire analysis indicated that total number of dogs owned over a period was a risk factor (P<0.006), but not a history of red fox hunting (P>0.6). Rodent ecology studies revealed an association between density indices of voles (Microtus limnophilus) and village AE prevalence rates, on the one hand, and village landscape characterised by a ratio of scrub/grassland to total area above 50% (P<0.005). Long-term transmission of Echinococcus multilocularis and risk of zoonotic infection of south Gansu farmers may be related ultimately to a process of deforestation driven by agriculture. This in turn probably results in creation of optimal peri-domestic habitats for rodents that serve as intermediate host species (such as M. limnophilus) and subsequent development of a peri-domestic cycle involving dogs.

Adult↗
PubMed2000

Oxidative damage to mitochondrial DNA and activity of mitochondrial enzymes in chronic active lesions of multiple sclerosis.

Soluble products of activated immune cells include reactive oxygen species (ROS) and nitric oxide (NO) with a high potential to induce biochemical modifications and degenerative changes in areas of inflammation in the central nervous system (CNS). Previously, we demonstrated an increased production of ROS by activated mononuclear cells (MNC) of patients with multiple sclerosis (MS) compared to those of controls, and development of oxidative damage to total DNA in association with inflammation in chronic active plaques. The current study aimed to determine whether mitochondrial (mt)DNA is affected by oxidative damage, and whether oxidative damage to mitochondrial macromolecules (including mtDNA) is associated with a decline in the activity of mitochondrial enzyme complexes. Using molecular and biochemical methods we demonstrate a trend for impaired NADH dehydrogenase (DH) activity and a possible compensatory increase in complex IV activity in association with oxidative damage to mtDNA in chronic active plaques. Immunohistochemistry confirms the increase of oxidative damage to DNA predominantly located in the cytoplasmic compartment of cells in chronic active plaques. These observations suggest that oxidative damage to macromolecules develops in association with inflammation in the CNS, and may contribute to a decline of energy metabolism in affected cells. As observed in neurodegenerative diseases of non-inflammatory origin, decreased ATP synthesis can ultimately lead to cell death or degeneration. Therefore, elucidation of this pathway in MS deserves further studies which may identify neuroprotective strategies to prevent tissue degeneration and the associated clinical disability.

Adolescent↗
PubMed2000

Isolation and characterization of Tn7 transposase gain-of-function mutants: a model for transposase activation.

Tn7 transposition has been hypothesized to require a heteromeric transposase formed by two Tn7-encoded proteins, TnsA and TnsB, and accessory proteins that activate the transposase when they are associated with an appropriate target DNA. This study investigates the mechanism of Tn7 transposase activation by isolation and analysis of transposase gain-of-function mutants that are active in the absence of these accessory proteins. This work shows directly that TnsA and TnsB are essential and sufficient components of the Tn7 transposase and also provides insight into the signals that activate the transposase. We also describe a protein-protein interaction between TnsA and TnsC, a regulatory accessory protein, that is likely to be critical for transposase activation.

Enzyme Activation↗
PubMed2000

Is the endogenous peroxyl-radical scavenging capacity of plasma protective in systemic inflammatory disorders in humans?

Systemic inflammatory response syndrome (SIRS) in humans is associated with heightened intravascular oxidative stress. The clinical significance of plasma endogenous antioxidative capability in SIRS remains undetermined. Time-sequence changes of plasma total radical-trapping antioxidant parameter (TRAP) and its components were measured in 135 patients with various clinical conditions leading to SIRS. The results were correlated with clinical parameters. Plasma TRAP significantly depressed upon diagnosis of SIRS (SIRS vs. healthy subjects (n = 50), 605.7 +/- 20.4 vs. 803.4 +/- 30.8 microM Trolox equivalent, p <.001). In survivors (n = 86), TRAP declined further during the course of SIRS, followed by a mild recovery at the end of follow-up. General linear mixed model analysis revealed that uric acid, vitamin C, vitamin E and unidentified antioxidants contributed to most of the changes in TRAP (each factor p <.001). In nonsurvivors (n = 49), TRAP increased steadily until death, and the increase was predominantly the result of the increased contribution of bilirubin (p <.01). Higher TRAP levels were not correlated with diminished blood oxidants formation (r = -0.13, p.05), lower intensity of lipid peroxidation (r = 0.261, p <.05) or lesser disease severity of SIRS. The results do not support the hypothesis that the endogenous peroxyl radical scavenging ability of plasma plays a protective role in the course of SIRS.

Aged↗
PubMed2000

Epidemiologic study of type 2 diabetes in Taiwan.

Diabetes mellitus (DM) in adults is a global health problem, although its prevalence varies widely between different populations and the rate has generally increased worldwide. In Taiwan, the mortality rate from DM has almost doubled over the past 10 years. The prevalence of DM in Taiwan was established between 1985 and 1996 and the rates were between 4.9 and 9.2%. The prevalence of impaired glucose tolerance (IGT) was 15.5% (men 15% and women 15.9%). The prevalence of DM and IGT increased significantly with age for both genders. The significant factors associated with newly diagnosed DM were age, BMI, family history of DM, systolic blood pressure (hypertension), physical activity and serum triglyceride levels. The prevalence of large vessel disease (LVD) in DM and non-diabetic subjects were 20.0 and 12.9%, respectively. Among diabetics, 15.8% had ischemic heart disease (IHD), 1.7% leg vessel disease (leg VD), and 2.5% stroke. In non-diabetics, the prevalence of the aforementioned macroangiopathies were 11.5, 0.2 and 1.2%, respectively. The diabetics had a significantly higher prevalence of macrovascular disease than non-diabetic subjects. The most significantly associated with the LVD was serum cholesterol levels. Serum cholesterol and HbA1(c) were significantly associated with the development of IHD. Cigarette smoking and female gender were significantly associated with the leg VD. The prevalence of diabetic retinopathy (DR) was 35.0%. (background DR 30%, preproliferative DR 2.8% and proliferative DR 2.2%, respectively.) The prevalence of DR for previously and newly diagnosed diabetics were 45.2 and 28.3% (men 42.8 vs. 33.3% and women 47.5 vs. 24.8%), respectively. From multiple logistic regression analysis, duration of DM was the most important risk factor related to DR. Diabetic subjects treated with insulin had a higher risk of developing retinopathy than those treated with dietary control. The prevalence of nephropathy and neuropathy were 12.9 and 23.5%, respectively. For those patients with and those without nephropathy and neuropathy, the duration of DM, percentage of insulin treatment, percentage of hypertension, and fasting plasma glucose were significantly different. Diabetic duration, hypertension, insulin treatment and glycemic control consistently correlated with nephropathy and neuropathy. In conclusion, the prevalence of DM in Taiwan was between 4.9 and 9.2%, and the prevalence of IGT was 15.5%. The possible risk factors of newly diagnosed diabetes were age, family history of DM, BMI, SBP (hypertension), physical activity and triglyceride levels. Diabetes in Chinese subjects share many characteristics similar to other Asian populations. The burden imposed by the chronic complications of diabetes is massive. In Taiwan, the mortality rates from DM have increased greatly over the past 10 years. Reduction of the modificable risk factors such as BMI, hypertenion and dyslipidemia, and increase of physical activity and good glycemic control through public health efforts may help to reduce the risk of DM and its chronic complications.

Adult↗
PubMed2000

Is Chlamydia pneumoniae present in brain lesions of patients with multiple sclerosis?

We investigated the presence of Chlamydia pneumoniae in 81 normal and pathological specimens obtained from postmortem brain tissues of patients with multiple sclerosis and with other neurological or nonneurological diseases. The assays used included PCR amplification of all DNA samples in the initial study. Culture and a second PCR amplification of the organism in a subset of 19 brain specimens were also performed in two separate laboratories. All results were negative. Thus, this study on a large number of brain tissues suggests that C. pneumoniae is not involved in inflammatory demyelination.

Brain↗
PubMed2000

Improved PCR-based subtractive hybridization strategy for cloning differentially expressed genes.

An improved PCR-based subtractive hybridization strategy was used to clone apoptosis-related genes induced by all-trans retinoic acid (ATRA) from human promyelocytic leukemia cell line HL-60 cells. The protocol used the cap-finder method, long-distance PCR, streptavidin magnetic bead-mediated subtraction and spin column chromatography. Twenty-seven clones related to apoptosis were identified by reverse dot blot assay. Seventeen were known genes, of which seven have been reported to be apoptosis related. The remaining 10 were unknown genes, five of which were sequenced and named apr-1 to apr-5. apr-1, apr-2, apr-3 and TNF were reidentified by reverse dot blot, and it is suggested that they might be related to apoptosis. The results suggest that this strategy might be efficient for large-scale cloning of differentially expressed genes in target cells.

Apoptosis↗
PubMed2000

[Foundational study of subcritical water chromatography].

AIM: To study the subcritical water chromatographic discipline of compounds with medium and high polarity on the capillary and packed column. METHODS: A packed and capillary subcritical water chromatography-FID detection system was built up. Six alcohols were well separated on a C18 column and the influence of temperature on chromatographic behavior of alcohols with different polarity was studied. The influence of temperature and pressure on chromatographic behavior of benzoic acid and gensenoside Rg1 on a SE-54 capillary column were also studied. RESULTS: Increasing temperature resulted in the decreasing polarity of mobile phase, shortened retention times of components separated, narrowed peak shape and improved tailing as well. CONCLUSION: Temperature programming could be used successfully to separate compounds with various polarity selectively. Thermostable capillary column could enlarge the range of temperature even more.

Chromatography, Liquid↗
PubMed2000

Evidence for voltage-gated potassium channel beta-subunits with oxidoreductase motifs in human and rodent pancreatic beta cells.

Voltage-gated K(+) channel alpha subunits (K(V) alpha) have been previously identified in pancreatic islet beta-cells where it has been suggested they have a role in membrane repolarization and insulin secretion. Here we report the cloning of the three mammalian K(V) beta subunits, including splice variants of these subunits, from both human and rat pancreatic islets and from the rat insulinoma cell line INS-1. Two of the splice variants, K(V) beta1a and K(V) beta3, previously reported to be neuronal tissue specific, are expressed in islets and INS-1 cells. In addition, a splice variant of K(V) beta2 that lacks two potential protein kinase C phosphorylation sites at the amino terminus is present. Immunoblot analysis suggests a high level of K(V) beta2 subunit protein in rat pancreatic islets and immunoprecipitation with anti-K(V) beta2 antibody pulls down a protein from INS-1 cells that reacts with anti-aldose reductase antibody. The K(V) beta subunits, which are attached to the cytoplasmic face of the alpha subunits and are members of the aldose reductase superfamily of NADPH oxidoreductases, may have an as yet undetermined role in the regulation of insulin secretion by the intracellular redox potential. Finally, we suggest that a systematic nomenclature for K(V) beta subunits first proposed by McCormack et al. be adopted for this family of potassium channel subunits as it corresponds with the nomenclature used for their cognate K(V) alpha subunits.

Aldehyde Reductase↗
PubMed2000

Dysregulation of apoptosis: a possible mechanism leading to chronic progressive renal histological changes in lupus nephritis.

OBJECTIVE: To evaluate apoptosis in lupus nephritis and the relationship between the existence of apoptotic cells in renal tissue and histopathological or clinical changes. METHODS: Apoptosis was detected by in situ nick-end labeling techniques (TUNEL) in renal biopsies from 25 patients with type IV lupus nephritis (LN), 12 patients with IgA nephropathy IgAN, 4 patients with idiopathic mesangioproliferative glomerulonephritis (MsPGN) and 3 patients with acute poststreptococcal glomerulonephritis (APGN). Normal renal tissue obtained at nephrectomy for hypernephroma in 4 adults was used as control. Proliferating cells were identified by proliferating cell nuclear antigen (PCNA) in these patients. RESULTS: Compared to other proliferative glomerulonephritis and controls, the patients with lupus nephritis had less apoptotic cells, a higher ratio of PCNA + cells/TdT + cells (P/T) in renal tissues; and their P/T ratio in glomeruli and tubulointerstitium correlated with the chronicity index, r = 0.4983 (P = 0.0132), r = 0.8399 (P < 0.001), r = 0.6614 (P = 0.0033), respectively. P/T ratios in the glomerulus and tubule had a positive correlation with 24-hour urinary protein, r = 0.8554 (P < 0.001) and r = 0.7134 (P = 0.001); and a negative correlation with creatinine clearance (Ccr), r = -0.4880 (P = 0.0133) and r = -0.7229 (P = 0.001), which in tubules positively correlated with serum creatinine (Scr), r = 0.4107 (P = 0.0414). CONCLUSIONS: Apoptosis is reduced in proliferative lupus nephritis. Intense proliferation without a commensurate increase in apoptosis is a possible mechanism that leads to chronic progressive renal histopathological changes.

Adult↗
PubMed2000

[The distrubution of cell cycle on fibrolasts derived from the pathlogical scars and analysis of Fas gene mutations in keloids using polymerse chain Reaction-based single-strand conformation polymorphism].

OBJECTIVE: To explore the concrete mechanism which accounts for the different growth characteristics of normal skins and pathlogical scars and to identify if the mutations of Fas gene exist. METHODS: Six samples of normal skin, hypertrophic scars and keloids were collected. The means of cell culture was used, and only 6 - 10 passages fibroblasts were selected for experiment. The distribution of cell cycle and expression of protein p53 were analysed with flow cytometry, adherant cell analysis and sorting interactive laser coytometry (ACAS 570). Keloids and hypertrophic scar tissue and the peripheral blood of each patient were collected. After DNA was isolated from the samples, we used the single-stranded conformation polymorphism (SSCP) analysis and DNA sequencing to examine the structure of Fas gene. RESULTS: The expression of p53 protein on the fibroblasts derived from normal skin was significantly elevated in comparison to the hypertrophic scars with lowest propagative fibroblasts. A large percent of fibroblasts derived from the peripherial areas of keloids distributed in G(2), S and M periods with low levels of p53 protein. On the other hand, fibroblasts derived from the central areas of keloids distributed mostly in G(0) and G(1) periods with higher expression of p53 protein. Mutation in Fas gene was identified and confirmed in keloid tissue of 20% (2/10) of keloid patient, which may cause loss of function and contribute to the pathogenesis of keloid. A deletion of the nucleotide "A" at the same position was found, which caused a frameshift mutation in exon 9. CONCLUSION: The difference of the distributions of cell cycle and expression of protein p53 may account for the different growth characteristics in pathlogical scar and normal skin. Mutations in Fas gene may lead to abnormal apoptosis of fibroblasts in keloids, and may contribute to the pathogenesis and progression of keloids.

Adult↗
PubMed2000

[Effect of sample solvents on retention in packed column supercritical fluid chromatography].

Factors affecting the retention in supercritical fluid chromatography(SFC) on C18 and NH2 packed columns have been studied. These factors include the sampling solvent, continuous injection, stationary phase type and concentration of modifier. When supercritical carbon dioxide or low concentration(less than 0.5%) of methanol is employed as the mobile phase, retention time increases with the polarity of the solvent on NH2 column, while it keeps almost constant on C18 column. Methanol will cover the active sites on the surface of the bonded phase, forming the "pseudo" stationary phase, which will lower the interaction between the analytes and the stationary phase, hence the shorter will be the retention time. The hydrogen bond between stationary phase (including the amino group and the remaining hydroxyl group) and methanol is the most obvious. So it's quite more evident on NH2 column than on C18 column that the delaying effect of the solvent, with methanol, acetone and chloroform in decreasing sequence, encourages the elution of the analytes during continuous injections. The elution will recover to the first injection after adequate interval has passed, i.e., more than 10 column volumes. When the methanol concentration is greater than 1.0% in carbon dioxide, the effect decreases and becomes negligible. The solvent effect is significant to the reasonable injection and reproducible chromatographic data in packed column SFC.

Carbon Dioxide↗
PubMed2000

[The clinical analysis of 260 combined surgery of glaucoma and cataract].

PURPOSE: To evaluate the efficacy of the combined surgery of glaucoma and cataract. METHODS: We reviewed 260 consecutive cases (279 eyes) who underwent the combined procedure of glaucoma and cataract. The patients were divided into three groups: group 1: extracapsular cataract extraction combined with trabeculectomy; group 2: extracapsular cataract extraction and intraocular lens implantation combined with trabeculectomy; group 3: cataract phacoemulsification and intraocular lens implantation combined with trabeculectomy; We analyzed and compared the postoperative visual acuity (VA), intraocular pressure(IOP) and complications among three groups. RESULTS: 16.2%, 32.4% and 43.5% of patients in three groups achieved 0.3 or better VA. The VA improved rate were 46.6%, 70.4% and 78.3% respectively. The mean postoperative IOP of three groups were 12.72 +/- 6.66 mmHg(1 mmHg = 0.133 kPa), 13.01 +/- 5.26 mmHg, 12.63 +/- 4.66 mmHg(compared with preoperative IOP, P < 0.01). The complications of group 3 were much less than those of the other two groups. CONCLUSION: The combined surgery can control the IOP effectively; The triple procedure can improve the VA rapidly and the phacoemulsification technique can decrease the complications.

Adult↗
PubMed1999

Myoglobin-containing carbon-paste enzyme microelectrodes for the biosensing of glucose under oxygen-deficit conditions.

The response of first-generation glucose oxidase (GOx) amperometric glucose biosensors is strongly dependent on the concentration of the oxygen cosubstrate. The incorporation of the natural oxygen binder myoglobin into a GOx-containing carbon-paste matrix is shown to satisfy the oxygen demand of the enzymatic reaction and to provide convenient biosensing of glucose in oxygen-free solutions. Such use of myoglobin-containing mineral oil thus offers an attractive alternative to the use of oxygen-rich fluorocarbon pasting liquids. Further improvements are observed upon doping the fluorocarbon oil with myoglobin. Factors affecting the oxygen independence of the new enzyme microelectrodes, including the myoglobin loading or length of the oxygen reservoir, have been optimized. The myoglobin-doped mineral oil or Kel-F-based carbon-paste enzyme microelectrodes display a highly stable glucose response over prolonged (6-7 h) operations in oxygen-free solutions, indicating no depletion of the internal oxygen supply.

Biosensing Techniques↗