Biomedical subjects

L Lu

Publications and source records attributed to L Lu.

At least 289 records · Page 16Linked to original sources

PubMed1998

Nerve injection injury with botulinum toxin.

The therapeutic use of botulinum toxin (Botox) is increasing in popularity. Previous studies have shown that various drugs, especially when injected intrafascicularly, can cause major nerve damage. This study evaluates the potential for neurotoxicity of botulinum toxin in a rat sciatic nerve model. Lewis rats were randomly assigned to one of six groups (n = 10/group). Group 1, 2, and 3 rats received, respectively, an intrafascicular, extrafascicular, and extraneural injection of 50 microl of botulinum toxin (50 UI/ml). Group 4, 5, and 6 rats received 50 microl of 10% phenol as a positive control. Five animals received saline as a negative control. Animals were sacrificed at 2 and 7 weeks. Nerves were harvested and processed for histology and morphometry. Nerves in all botulinum toxin groups retained a normal architecture without cellular infiltration or demyelination. The number and diameter of fibers, the thickness of myelin, and the percentage of neural tissue were comparable with normal controls. Nerves injected intraneurally with phenol presented with severe damage, demyelination, and inflammation at 2 weeks and showed signs of early regeneration at 7 weeks. This study demonstrates that in a rat model, even direct intraneural injection of botulinum toxin caused no damage. This information should encourage the reconstructive surgeon to consider broader applications of this drug.

Animals↗

PubMed1998

A novel, rapid in cell RNA amplification technique for the detection of low copy mRNA transcripts.

Growing interest now focuses on improvements of in situ polymerase chain reaction (PCR) technology for the detection of DNA and RNA cellular sequences. In this study, reverse transcription PCR in situ hybridisation (RT PCR-ISH) was developed and used to determine gene expression of pyruvate dehydrogenase in a cell model system, using human peripheral blood lymphocytes (PBLs). The success of in cell RNA amplification depends on the type of cell/tissue fixation, cell permeabilisation, and the efficiency of reverse transcription and cDNA amplification. This paper presents new approaches to overcome the critical aspects of fixation, permeabilisation, and reverse transcription when performing in cell RNA amplification. A novel fixative, "Permeafix", possessing fixative and permeabilisation properties, was used for cell fixation procedures. "Permeafix" obviated the need for pre-amplification proteolysis, facilitating entry of PCR reagents to target sequences within the cell. In addition, a simple on step RNA in cell amplification protocol using recombinant Thermus thermophilus (rTth) DNA polymerase, which reverse transcribes mRNA efficiently to cDNA and then catalyses cDNA amplification, was used. The value of a semi-junctional primer system for in cell gene expression studies, without the need to perform DNase digestion, is demonstrated.

DNA Primers↗

PubMed1998

beta-adrenergic stimulation induces transient imbalance between myocardial substrate uptake and metabolism in vivo.

At steady state, a balance is expected between net myocardial uptake of the principal exogenous carbon substrates and the rate at which these substrates are metabolized. Such a balance is present when the sum of the oxygen extraction ratios (OERs) for glucose, lactate, and free fatty acids (FFA) is near unity. We have previously observed that systemic administration of the beta-adrenergic agonist isoproterenol (Iso) induces a state of excess myocardial substrate uptake relative to the rate of substrate metabolism, reflected by a sum of OERs significantly >1.0. This occurs in conjunction with an Iso-stimulated increase in circulating insulin levels. The goal of the present study was to determine whether this excess substrate uptake depends on the effects of insulin and time. In open-chest anesthetized pigs, myocardial blood flow, substrate uptake, and oxygen consumption were measured at baseline and during systemic administration of Iso (0.08 microgram. kg-1. min-1 iv) under the following conditions: group 1 (n = 10), normal endogenous insulin release; group 2 (n = 10), inhibition of endogenous insulin release with somatostatin; group 3 (n = 7), at 45 and 90 min Iso; group 4 (n = 7), at 45 and 90 min Iso, with exogenous insulin given during the latter measurement. In group 1, plasma insulin rose fivefold with Iso while the sum of the OERs for glucose, lactate, and FFA increased from 0.92 +/- 0.21 at baseline to 1.57 +/- 0.17 with Iso (P < 0.01). In group 2, somatostatin blunted the increase in insulin with Iso and there was no significant change in the sum of OERs between baseline and Iso. In group 3, the sum of OERs increased from 0.95 +/- 0.11 at baseline to 1.69 +/- 0.20 at 45 min Iso (P < 0.01), similar to the response of group 1. However, the state of excess substrate uptake was transient; by 90 min Iso the sum of OERs declined to 0.69 +/- 0.21 (P < 0.05 vs. 45 min Iso). In group 4, excess substrate uptake could not be sustained at 90 min Iso despite administration of exogenous insulin. Systemic beta-adrenergic stimulation causes a transient condition of myocardial substrate uptake in excess of metabolism. Increased plasma insulin is necessary to produce this condition, but a high insulin level does not prolong the condition.

Adrenergic beta-Agonists↗

PubMed1998

Retinal pigment epithelium cell culture on thin biodegradable poly(DL-lactic-co-glycolic acid) films.

Thin films of 50:50 and 75:25 poly(DL-lactic-co-glycolic acid) (PLGA) were manufactured with a controlled thickness of less than 10 microm. The effect of PLGA copolymer ratio on in vitro cell attachment, proliferation, morphology, and tight junction formation was evaluated using a human D407 retinal pigment epithelium (RPE) cell line. Almost complete cell attachment was achieved on both PLGA films after 8 h of cell seeding, which was comparable to that on tissue culture polystyrene (TCPS) controls. The initial cell seeding density affected attachment, and the optimal value for 50:50 PLGA was 25000 cells cm(-2). After 7 days of in vitro culture, cell density on 50:50 and 75:25 PLGA films increased 45 and 40 folds, respectively, and a 34-fold increase was observed on TCPS. The RPE cells cultured on PLGA films at confluence had a characteristic cobblestone morphology. Confluent RPE cells also developed normal tight junctions in vitro which were concentrated mainly at the apical surfaces of cell-cell junctions. These results demonstrated that thin biodegradable PLGA films can provide suitable substrates for human RPE cell culture, and may serve as temporary carriers for subretinal implantation of organized sheets of RPE.

Biocompatible Materials↗

PubMed1998

The utility of Hayashi's quantification theory type 2 for the rapid assessment of the epidemiological survey in the developing countries--in a case of the vaccine coverage survey in Yunnan Province, China.

It is difficult to conduct the epidemiological survey with accurate statistical theory in the developing countries due to the problems especially emerged in the developing countries such as no availability of the accurate population data, limitation of the time for survey, geographical obstacle and financial problems. In the consideration of the health needs in those countries, results of the epidemiological survey should be reflected in the present health projects as rapidly as possible. The authors conducted the survey for the immunization coverage of oral poliomyelitis vaccine(OPV) in China by the questionnaire and interview. The data was analyzed by using the Hayashi's quantification theory type 2 and made clear about the relationship between the health behaviors for immunization among residents and several factors. It is considered that this theorem can provide the obvious numeral materials about multi-factorial cause effect relationship for the decision making and is useful for the rapid assessment or initial survey in the developing countries.

Chi-Square Distribution↗

PubMed1998

Isolation of amelogenin-positive ameloblasts from rat mandibular incisor enamel organs by flow cytometry and fluorescence activated cell sorting.

The purpose of this study was to use amelogenin as a marker to examine the feasibility of isolating ameloblasts from enamel organ cell populations by fluorescence activated cell sorting. After treating dissected rat enamel organs with proteolytic enzymes to loosen cell attachments and labial connective tissues, dissociated cell suspensions were fixed, then immunostained with rabbit anti-rM179 recombinant amelogenin antibody and FITC-conjugated goat anti-rabbit Ig G antibody. Flow cytometry indicated that about 70% of the total cell sample and virtually all the larger cells therein were amelogenin-positive. Fluorescence activated cell sorting yielded a sample of amelogenin-positive cells at 97% purity. Immunofluorescence microscopy indicated that these isolated amelogenin-positive cells varied widely in size and morphology. This was attributed to loss of intercellular support for ameloblasts once they were dissociated from each other, and to some fragmentation caused when the cells were initially physically removed from the teeth. The results demonstrate that viable ameloblast cell fractions, especially representing cells at the secretory stage, can be purified from enzymic digests of rat enamel organ by sorting on the basis of cell size alone. From these fractions, subpopulations of ameloblasts may be identified when differentiation specific cell surface markers become available.

Ameloblasts↗

PubMed1998

[The characteristics of plasma--sprayed coatings of hydroxy apatite in vitro].

In order to investigate the stability of Hydroxyapatite (HA) coated material, the plasma-sprayed coatings of HA were divided into four groups: 1. Keeping in water vapour at 125 degrees C, with a pressure of 0.15 MPa for 6 hr; 2. Heating at 650 degrees C in air for half an hr; 3. Keeping in water vapour at 490 degrees C, with a pressure of 0.01 MPa for 2 hr; and 4. The control. The XRD, FTIR analysis and the dissolution test were carried out. The results showed: 1. The degree of crystalization in XRD analysis was 3. > 1. > 2. > 4.; 2. The ampitude of OH- peak in FTIR analysis was 3. > 1. > 2. > 4. and 3. The dissolution rate in tris-HCl buffer was 3. < 1. < 2. < 4. The conclusions were 1. The treating with water vapour could decrease the transformation temperature which was needed to convert the amorphous phase into cystalline phase; 2. Water vapour treatment could accelerate the transformation of Z-TCP, TCPM into crystalline HA; 3. Water vapour treatment could promote the structural integrity of plasma--sprayed coated of and HA and 4. Water vapour treatment could lower the dissolution rate of HA coated in Tris-HCl buffer.

Coated Materials, Biocompatible↗

PubMed1998

The stress-bearing ability of mucosa in complete denture-wearers.

OBJECTIVE: The purpose of this study was to investigate the stress-bearing ability of mucosa in complete denture-wearers. METHODS: The maximum bite force (MBF) was obtained in 31 voluntary complete denture-wearers with a miniature bite force instrument and a set of central bearing devices. The projective stress-bearing area in the mandible (PAM) was measured through the impression surface of the mandibular complete denture. The authors evaluated the stress-bearing ability (SBA) of mucosa in complete denture-wearers by the formula MBF/PAM. RESULTS: The results showed that there was a significant positive correlation between the MBF (the mean was 15.13 kg in men and 11.39 kg in women) and the PAM (the mean was 17.15 cm2 in men and 14.46 cm2 in women) and that there was no significant difference between the mean of the SBA in men (0.89 kg/cm2) and the mean of the SBA in women (0.79 kg/cm2). The mean value of the maximum pressure borne by the mandibular edentulous region was 82 kPa (0.84 kg/cm2). CONCLUSIONS: The SBA may become a valuable parameter for the design of both occlusion and reinforcement in the denture construction and for the selection of the maximum load in mechanical tests of complete dentures.

Aged↗

PubMed1998

[Study on certified reference material of germanium in Ganoderma lucidum].

Analytical reference material of Ge in Ganoderma lucidum is designed and prepared for accurete analysis, monitoration and evaluation in trades of farming, forestry, medicine and food hygiene for Ge. It is used in technical training, technical assessing, monitoring, data arbitrating and analytic method verifing for professional supervisors. This reference material has been certified by graphitic oven atomic absorption spectrometry, hydride spectrophotometry, polarography, chemical separation spectrophotometry, atomic fluorescence method and x-ray fluorescence method. According to Grubb's law to judge the data of each group, it is confirmed that all of seven groups certified crude data are normal distribution by checking normality D. The arithmatic mean value of all data is 0.38 microgram/g. Standard deviation is 0.08 microgram/g.

Drugs, Chinese Herbal↗

PubMed1998

[Diagnostic evaluation of magnetic resonance urography in urinary tract dilatation and obstruction].

OBJECTIVE: To evaluate the diagnostic value of magnetic resonance urography (MRU). METHODS: Two hundred and one patients were examined, 92 patients with urinary tract dilatation using a modified, heavily T2-weighted fast spin-echo pulse sequence and fat-suppression pulse aid. Postprocedure processing was performed with a maximum-intensity-projection (MIP) algorithm. RESULTS: In the 92 patients with urinary tract dilatation, 86 had obstructive urinary tract dilatation 6 non-obstructive urinary tract dilatation. In the 86 patients, 14 had ureteral carcinoma, 19 calculus, and 13 benign stricture, 23 congenital ureteral stricture/or with anomalies, 7 ureteral obstructive caused by extrinsic pelvis disease, and 10 bladder carcinoma involved ureter. In the 6 patients, 5 had nervous bladder. MR urography provided the high-resolution image of the urinary tract and determined the presence of obstruction. CONCLUSION: MR urography is a reliable noninvasive method for depicting the urinary tract.

Adolescent↗

PubMed1998

Induction of anti-DNA antibodies by immunization with activated lymphocytes and active chromatin.

OBJECTIVE: To investigate the primary autoantigens which contribute to the production of anti-DNA antibodies. These antibodies are serological hallmark and pathogenic factor of systemic lupus erythematosus (SLE). METHODS: Nonautoimmune predisposed BALB/c mice were immunized with concanavalin A (Con A) activated, lipopolysaccharide (LPS) activated and nonactivated syngeneic spleen cells. Nuclei and chromatin from activated/nonactivated lymphocytes were isolated and syngeneic mice were immunized. Sera were taken after the third immunization. IgG anti-dsDNA antibody was determined by ELISA (calf thymus DNA treated with S1 nuclease was used as the coated antigen). The glomerular IgG deposition was observed by immunofluorescence one month after the third immunization. RESULTS: Con A activated T cells and LPS activated B cells induced anti-double stranded (ds) DNA antibody in syngeneic nonautoimmune BALB/c mice and formed the glomerular IgG deposition. Further studies showed that active chromatin isolated from activated lymphocytes induced anti-ds DNA antibody, but not resting chromatin isolated from nonactivated lymphocytes. CONCLUSIONS: Activated lymphocytes and their active chromatin could be the autoimmunogen(s) driving the anti-dsDNA antibodies. The change of chromatin's antigenicity by environmental factors and genetic background may be the common pathway to SLE pathogenesis.

Animals↗

PubMed1998

[Study on gene expression of TGF beta 1 and its receptor in leukemia cells and the serum TGF beta 1 level in the patients with acute leukemia].

OBJECTIVE: To investigate the mechanism by which TGF beta 1 inhibits the growth of leukemic cells and the significance of serum TGF beta 1 level in acute leukemia(AL) patients. METHODS: RT-PCR was used to detect gene expression of cytokines including IL-1, IL-3, IL-6, TGF beta 1 and their receptors (R) in leukemic and normal cells. Leukemic colony assay was carried out to determine the effect of TGF beta 1 on the growth of leukemic cells and the serum TGF beta 1 level in 33 AL patients were measured by ELISA. RESULTS: TGF beta 1 was found to significantly inhibit the proliferation of leukemia cells of HL-60, K562 and DAMI cell lines. Furthermore, a variety of leukemia cell lines including HEL, HL-60, K562, U937, DAMI, MEG-01, HUT78 and CA were found to express mRNAs for TGF beta 1 and its receptor. In addition, TGF beta 1 was found to be able to evidently down-regulate the expression of mRNAs for IL-6, IL-6R, IL-3, GM-CSFR in DAMI cells and, interestingly, up-regulate TGF beta 1 gene expression in the cells per se before the cells showed DNA fragmentation, a molecular hallmark for cell apoptosis. It was shown that serum TGF beta 1 levels were significantly decreased in leukemic patients, restored to normal in the patients achieved complete remission, and tended to decrease again in the recurrent patients. CONCLUSION: 1. TGF beta 1 may act as an inhibitory autocrine factor in the proliferation of leukemia cells; 2. the mechanism by which TGF beta 1 inhibits the growth of leukemia cells involves its down-regulating expression of positive cytokines and receptors and up-regulating TGF beta 1 expression in leukemia cells per se; 3. serum TGF beta 1 is a valuable parameter in monitoring the prognosis of leukemia and weakened control of TGF beta 1 on leukemia cells may play an important role in the pathogenesis of AL.

Adult↗

PubMed1998

Linear and nonlinear analysis of heart rate variability during lower body negative pressure.

In order to measure the changes of heart rate variability (HRV) under lower body negative pressure (LBNP), time and frequency domain parameters as well as the relative LZ Complexity were used to analyse HRV. Fifteen healthy male subjects in supine position were subjected to sequential LBNP (-2.7 kPa 2 min, -4.0 kPa 3 min, -5.3 kPa 5 min, -6.7 kPa 10 min). They were divided into two groups: intolerant group (group A) and tolerant group (group B). There was a similar decreasing trend for R-R interval at -5.3 kPa and -6.7 kPa in both groups. Spectral analysis showed no significant alternations in both groups. At -6.7 kPa, complexity showed significant differences from the baseline values in both groups. Furthermore, there was a more significant reduction of complexity in group A than that in group B. These results showed that LBNP is associated with a decrease of HRV complexity. In addition, this study suggests that nonlinear dynamics measurement of heart rate variability may provide a sensitive index in the regulation of cardiovascular system.

Adult↗

PubMed1998

[Anaerobic threshold as determined by gas metabolic parameters].

In order to demonstrate the possibility of evaluating anaerobic threshold (AT) by gas exchange parameters, treadmill exercise tests were made by 1-min increment protocol in 25 healthy young men. Ten parameters of gas exchange were collected when AT was reached. The analysis showed that correlation between VO2 and VE (r = 0.8004) or VCO2 (r = 0.9743) are high. While correlation between VO2 and RQ (r = 0.4491) or HR (r = 0.4666) are significantly lower. So the accuracy of VE and VCO2 is higher than that HR or RQ for the determination of AT.

Adolescent↗

PubMed1998

[Heart rate variability analysis under lower body negative pressure].

In order to assess the changes of HRV in relation to hemodynamic responses to LBNP, 40 healthy male volunteers were exposed to progressively increasing LBNP. Changes of SV, CO and BP were measured and HRV was analyzed. Thirty-four subjects (Group A, with good tolerance) were able to tolerate all stages of LBNP, and other 6 subjects (Group B, with poor tolerance) showed presyncopal signs and symptoms during the last 5min of LBNP exposure. In both groups, HRV, SV, CO decreased significantly during LBNP. Group B had lower HRV, SV, CO than group A pre-LBNP, during-LBNP and post-LBNP. The LF/HF ratio increased during LBNP in both groups, but increased more apparently in group B than group A at -6.7 kPa LBNP. The results showed that, when SV decreased to a certain degree, the sympathetic activity increased to the utmost. The onset of presyncopal signs could be attributed to the rapid withdrawal of sympathetic tone, and LBNP tolerance of a subject is closely related to both ejecting capability of the heart and the function of autonomic nervous system.

Adult↗

PubMed1998

[SEM and TEM observation on behaviour of invasion of squamous cell carcinoma of the tongue].

OBJECTIVE: To study the invasive behaviour of squamous cell carcinoma of the tongue. METHODS: The cryofracture technique for scanning electron microscope (SEM) and transmission electron microscope (TEM) was used. RESULTS: Cancer cells invaded surrounding tissues by proliferation and penetration en masse, and projected with pseudopodia and lamellipodia. The tensile fibers along and under the cell membrane protruded into the interdigitated filopodia. There were dilatation of intercellular spaces, less number of desmosomes and few gap junctions. All the properties above-described together with increase of cell motility, lytic activity, and decrease of intercellular adhesion were likely to contribute to invasiveness. CONCLUSION: In addition, it was identified that highly dense lymphocytes enclosed cancer nest, which could inhibit invasive action of cancer cells.

Adult↗

PubMed1998

[Effect of TNF-alpha monoclonal antibody on tissue lipopolysaccharide-binding protein mRNA expression in rats after thermal injury].

OBJECTIVE: To explore the effects of tumor necrosis factor-alpha (TNF-alpha) monoclonal antibody (MAb) on tissue TNF-alpha and lipopolysaccharide-binding protein (LBP) mRNA expression, and multiple organ dysfunction in rats after thermal injury. METHOD: 24 male Wistar rats were subjected to a 35% total body surface area full-thickness thermal injury. RESULT: The tissue TNF-alpha and LBP mRNA expressions of liver, lung, intestine, and kidney were markedly increased (P < 0.05 approximately equal 0.01) after thermal injury. Treatment with TNF-alpha MAb could significantly lower TNF-alpha mRNA expression of lung, intestine and kidney, but had no effect on liver TNF-alpha mRNA expression (P > 0.05). Similarly, the tissue LBP mRNA expression also decreased significantly (36.0% - 72.9%), and returned to normal in lung, intestine and kidney. In addition, biochemical parameters including GPT, TBiL, BUN, CK-MB, and LDH were markedly elevated after thermal injury, and decreased significantly after treatment with TNF-alpha MAb. CONCLUSION: The increase of tissue TNF-alpha gene expression caused by thermal injury might be associated with a marked elevation of tissue LBP mRNA expression, which could contribute to the development of multiple organ dysfunction. The early use of TNF-alpha MAb seems to be effective in inhibiting significant LBP mRNA expression in various tissues and ameliorating multiple organ damage after major thermal injury.

Acute-Phase Proteins↗

PubMed1998

[Reconstructive lacrimal gland with free submandibular gland transfer for management of xerophthalmia].

OBJECTIVE: In order to seek more efficient surgical method to treat total xerophthalmia. METHOD: Microvascular submandibular gland transfer was used to reconstruct lacrimal gland for management of the dry eye. 5 cases (6 eyes) with total xerophthalmia were operated with this method. RESULTS: All the patients were followed up for 1 - 30 months. The results were satisfactory, the submandibular salivary gland relieved the dryness and improved visual acuities with negligible side effect. CONCLUSION: Microvascular submandibular gland transfer is potentially the best surgical solution to total xerophthalmia.

Adolescent↗