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Biomedical subjects

C L Li

Publications and source records attributed to C L Li.

At least 19 recordsLinked to original sources
PubMed2006

Association of uncultivated oral phylotypes AU126 and X112 with periodontitis.

OBJECTIVE: To discuss the relationship between uncultivated pathogenic bacteria and periodontitis. SUBJECTS AND METHODS: Specific polymerase chain reaction (PCR) primers were designed for phylotypes AU126 and X112; PCRs were applied to determine the prevalence of these phylotypes in 35 patients with chronic periodontitis, 26 patients with plaque-induced gingivitis and 20 healthy control subjects. RESULTS: The specificity of each primer is validated on the basis of the results from sequence analysis of PCR products. AU126 and X112 were detected in the subgingival plaque samples in all the three groups. The prevalence of AU126 in subgingival plaque in chronic periodontitis (77.1%) and plaque-induced gingivitis (61.5%) is relatively higher than that in the healthy subjects (10.0%), and the difference is statistically significant (P < 0.01). The prevalence of X112 in subgingival plaque in periodontitis patients (85.7%) is higher than that in healthy subjects (30.0%), the difference (P < 0.01) being equally statistically significant. The difference between the chronic periodontitis group and the plaque-induced gingivitis group (50.0%) is statistically significant (P < 0.05). CONCLUSIONS: It might be assumed that the novel uncultivated AU126 phylotype could possibly be related to chronic periodontitis and plaque-induced gingivitis, and that X112 might play a role in the progress of lesion from gingivitis to periodontitis.

Bacterial Typing Techniques↗
PubMed2006

The development and characterization of an HEK293-derived cell line for use in an intratumoral cytokine delivery system.

As part of ongoing work to develop a method of cytokine delivery for use as an intratumoral depot, we noted that HEK293 cells, encapsulated in alginate, died within 24-48 h after in vivo, intratumoral implantation. We hypothesized that the highly hypoxic and acidic conditions found inside the tumor was the cause of the cells' premature demise. Therefore, we set out to develop a cell line, derived from HEK293, that would survive these hostile conditions. The HEK293 line was selected in 0.3-0.5% oxygen conditions over several weeks, followed by a further 6-week period of culture in alternating hypoxic and normoxic conditions. The most rapidly growing clones were selected and grown in normoxic conditions for several weeks to ensure their stability. The clones were then compared to the original line in terms of cell proliferation in normoxia and hypoxia, colony-forming efficiency, and morphological characteristics. The resulting line was able to proliferate in the harshest of conditions and continues to release its biological payload after alginate microencapsulation.

Animals↗
PubMed2005

Comparative evaluation of the cerebral state index and the bispectral index during target-controlled infusion of propofol.

BACKGROUND: Cerebral state index (CSI) has recently been introduced as an intra-operative monitor of anaesthetic depth. We compared the performance of the CSI to the bispectral index (BIS) in measuring depth of anaesthesia during target-controlled infusion (TCI) of propofol. METHODS: Twenty Chinese patients undergoing general anaesthesia were recruited. CSI and BIS, and predicted effect-site concentration of propofol were recorded. The level of sedation was tested by Modified Observer's Assessment of Alertness/Sedation Scale (MOAAS) every 20 s during stepwise increase (TCI, 0.5 microg ml(-1)) of propofol. The loss of verbal contact (LVC) and loss of response (LOR) were defined by MOAAS values of 2-3 and less than 2, respectively. Baseline variability and the prediction probability (P(K)) were calculated for the BIS and CSI. The values of BIS(05) and CSI(05), BIS(50) and CSI(50), BIS(95) and CSI(95) were calculated at each end-point (LVC and LOR). RESULTS: Baseline variability of CSI was more than that of BIS. Both CSI and BIS showed a high prediction probability for the steps awake vs LVC, awake vs LOR, and LVC vs LOR, and good correlations with MOAAS values. CONCLUSION: Despite larger baseline variation, CSI performed as well as BIS in terms of P(K) values and correlations with step changes in sedation.

Adult↗
PubMed2005

Quantitative analysis of the photodegradation of emitting CdTe nanocrystals dispersed in glass films.

CdTe nanocrystals (NCs, green- and red-emitting) prepared by an aqueous method were embedded into transparent glass films (15-20 microm thick) using a sol-gel method. Photodegradation of the NCs in the films due to UV irradiation (365 nm) was investigated quantitatively by measuring the PL efficiency as a function of the irradiation time for various irradiation intensities at several temperatures. Since CdTe NCs prepared by an aqueous method incorporate sulfur atoms from the surfactant (thioglycolic acid) during prolonged reflux in an alkaline region, the surface of red-emitting NCs (3.9 nm phi) is much more sulfur rich than that of green-emitting ones (2.6 nm phi), as previously reported. Due to this composition difference, the degradation behaviors of the two types of NCs differ significantly. The photodegradation of green-emitting glass films depended linearly on the irradiation intensity, whereas that of red-emitting ones showed a quadratic dependence. The activation energies of the photodegradation for both types of films were similar, 304 +/- 9 and 288 +/- 7 meV/particle, respectively. The NCs in the film were more than 2 orders of magnitude more robust than those in colloidal solutions. Comparison of the degradation of the glass films in air and in an Ar atmosphere revealed that the main mechanism of the photodegradation of the green-emitting NCs was oxidization from the first electronically excited state. The mechanism of the red-emitting NCs was not oxidization but a surface change probably related to a surfactant reaction.

Cadmium↗
PubMed2005

Highly photoluminescent multilayer QD-glass films prepared by LbL self-assembly.

A novel and facile preparation method for layer-by-layer (LbL) self-assembled films incorporating quantum dots (QDs) and having intense photoluminescence (PL) from blue to red is presented. Functional sol-gel-derived glass layers prepared by the hydrolysis of 3-aminopropyltrimethoxysilane (APS) or 3-mercaptopropyltrimethoxysilane (MPS) have been used as a linkage between QD layers. Absorption, PL spectroscopy, transmission electron microscopy, and atomic force microscopy were employed for characterization, which revealed that the QDs in the prepared films had a nearly close-packed coverage and were not aggregated. The PL efficiencies of the QDs (CdTe or ZnSe, both are thioglycolic acid-stabilized) dispersed in the films were roughly half that of the initial colloidal solutions but reached 24% before a refractive index correction. The thickness of the red-emitting film with 10 CdTe QD layers was approximately 50 nm. The concentration of QDs in the film derived from the first absorption peak was approximately 0.01 M. Because the PL starts to show a red shift, the obtained concentration is practically the ultimate one in the glass matrix. The mercapto, amino, and carboxyl groups play important roles in LbL self-assembling processes.

Cadmium Compounds↗
PubMed2005

A comparison of urinary albumin excretion rate and microalbuminuria in various glucose tolerance subjects.

AIMS: To investigate the difference of urinary albumin excretion rate (UAER) and microalbuminuria (MAU) in various glucose tolerance subjects, especially between isolated-impaired glucose tolerance subjects and isolated-impaired fasting glycaemia subjects. METHODS: A total of 2934 subjects were divided into five groups with various glucose tolerances, based on a 75-g oral glucose tolerance test. Microalbuminuria was defined when urinary albumin excretion rate was between 20 and 200 microg/min. RESULTS: (i) The UAER in the newly diagnosed Type 2 diabetes mellitus group, impaired glucose tolerance/impaired fasting glycaemia group and isolated-impaired glucose tolerance group were all higher than that in the isolated-impaired fasting glycaemia group and normal glucose tolerance group, but it was comparable between isolated-impaired fasting glycemia group and normal glucose tolerance group. The prevalence of MAU and the odds ratio for MAU with adjustment for age and sex in various glucose tolerance groups showed the same trend as the UAER. (ii) After adjusting for age and sex, there is a significant association between logUAER and independent risk factors (partial correlation coefficients: r = 0.26 for 2-h post-challenge blood glucose, r = 0.26 for systolic blood pressure, r = 0.27 for diastolic blood pressure, r = 0.27 for body mass index and r = -0.13 for high density lipoprotein-cholesterol, all P < 0.001). The risks for MAU were 2-h post-challenge blood glucose, body mass index and diastolic blood pressure, while high density lipoprotein-cholesterol was protective. CONCLUSIONS: The urinary albumin excretion rate and prevalence of microalbuminuria were higher in isolated-impaired glucose tolerance subjects than those in isolated-impaired fasting glycaemia subjects. At early abnormal glucose tolerance stage, the increasing post-challenge glycaemia might be a more important risk factor for urinary albumin excretion rate and microalbuminuria than increasing fasting glycaemia.

Adult↗
PubMed2004

Ciliary neurotrophic factor injected icv induces adipose tissue apoptosis in rats.

Recent findings show that ciliary neurotrophic factor (CNTF) and leptin have similar effects on food intake and body weight, suggesting possible overlapping mechanisms. Intracerebroventricular (icv) injection of leptin results in adipose tissue apoptosis. To determine if CNTF has similar activity, male Sprague Dawley rats implanted with lateral cerebroventricular cannulas were randomly assigned to four treatment groups ( N = 8), including control (aCSF), 10 microg/day leptin, 1 microg/day CNTF, and 5 microg/day CNTF. Rats received daily icv injections for 4 successive days. Both leptin and CNTF (5 microg) decreased BW (8.6% and 11.77%, respectively, p <.05) and cumulative food intake was decreased 43% by leptin ( p <.05). Leptin and CNTF (5 microg) reduced adipose tissue mass in epididymal adipose (Epi) by 30 and 33.5%, ( p <.05), in inguinal adipose (Ing) by 51 and 55% ( p <.05), in retroperitoneal adipose (Rp) by 65 and 64% ( p <.05), and in intrascapular brown adipose (iBAT) by 34 and 25% ( p <.05), respectively. Gastrocnemius muscle was not affected. Leptin and CNTF (5 microg) increased apoptosis in Epi by 84 and 150%, respectively ( p <.05) and in Rp by 121 and 146%, respectively ( p <.05). Loss of adipocytes by apoptosis may provide an explanation for the unexpected delay in return to initial energy status following CNTF treatments.

Adipose Tissue↗
PubMed2004

Sentinel lymph node biopsy in breast cancer patients after overnight migration of radiolabelled sulphur colloid.

OBJECTIVE: To evaluate the performance and feasibility of sentinel lymph node biopsy in breast cancer patients using technetium-99m (99mTc) sulphur colloid and gamma probe. METHODS: From May 2000 to March 2001, 70 patients with a tumour less than 5 cm with clinically negative axillary lymph nodes underwent sentinel node biopsy followed by standard axillary dissection. 99mTc sulphur colloid was injected around the primary tumour the day before surgery and a gamma probe was used to detect the sentinel lymph node during the surgical procedure. Sentinel lymph node biopsy was compared with standard axillary dissection for its ability to accurately reflect the final pathological status of the axillary nodes. RESULTS: The sentinel lymph node was successfully identified in 67 of 70 patients (95.71%). The number of sentinel lymph nodes ranged from 1-5 (mean 1.5) and non-sentinel nodes ranged from 5-22 (mean 13.3). Of the 67 patients with successfully identified sentinel lymph nodes, 43.28% (29/67) were histologically positive. Sensitivity of the sentinel lymph node to predict axilla was 82.75%; specificity was 100%. Positive and negative predictive values were 100% and 88.3% respectively. The sentinel lymph node was falsely negative in five patients, yielding an accuracy of 92.53%. Sentinel lymph node biopsy was more accurate for T1 tumours than for T2 tumours. CONCLUSIONS: The gamma probe guided method after overnight migration of 99mTc sulphur colloid is technically feasible for detecting sentinel lymph nodes in most breast cancer patients, accurately predicting the axillary lymph node status, and appears more accurate for T1 lesions than for larger lesions. This minimally invasive axillary staging procedure represents a major advance in the surgical treatment of breast cancer.

Adult↗
PubMed2003

Anatomical study on the morphology and blood supply of the falciform ligament and its clinical significance.

The purpose of this study was to understand the clinical significance of the morphology and blood supply of the falciform ligament in laparoscopic surgery. The structure, blood vessel distribution and anastomoses of the falciform ligament were observed in 20 cases of living laparoscopy, 30 cadaveric specimens injected with latex and five cadaveric specimens with Indian ink and hyaline. The falciform ligament was formed by two sides of peritoneum and its length, largest and smallest width were 8.3+/-1.6 cm, 4.9+/-0.8 cm and 1.1+/-0.3 cm, respectively. The left inferior phrenic artery and middle segment artery of the liver formed a vessel that arched and gave off 6-12 branches to the falciform ligament. The veins of the falciform ligament drained into the left inferior phrenic vein, and were not accompanied by any artery. In conclusion, the vessels of the falciform ligament anastomose with multiple vessels and form a significant pathway of the collateral circulation in the liver. The falciform ligament is an important landmark in laparoscopic surgery.

Cadaver↗
PubMed2003

Bone marrow-derived stem cells and "plasticity".

Studies describing plasticity of somatic stem cells have become a focus of interest because clinical applications in the treatment of degenerative diseases would be at hand. In particular, bone marrow-derived cells and their potential to contribute to skeletal and cardiac muscle, liver, neurons and epithelium have recently been studied extensively. Nevertheless, results of these studies have not always been consistent with each other, and yet it remains to be resolved whether plasticity of adult stem cells truly exists. This review will discuss the role of bone marrow-derived stem cells in the field of experimental and clinical plasticity studies. Observations compatible with the concept of stem cell plasticity will be weighed against limitations of the experimental systems employed.

Adult↗
PubMed2002

Identification and characterization of mutations underlying Sanfilippo syndrome type A (mucopolysaccharidosis type IIIA).

Sanfilippo syndrome type A (mucopolysaccharidosis type IIIA; MPS IIIA) is caused by a deficiency of the lysosomal enzyme haparan N-sulphatase (NS). The genomic DNA segments of the NS gene from two Chinese patients with MPS IIIA were amplified by polymerase chain reaction, followed by DNA sequencing to study the molecular lesions. Four mutations (i.e. N42K, D235N, P293S and R377C) and five polymorphisms (i.e. IVS2-72A --> G, IVS2-26T --> C, IVS5+17C --> T, IVS5-37GC --> CTGT and R456H) were identified. Transfection of COS-7 cells with cDNA mutagenized to the corresponding mutations did not yield active enzyme, demonstrating the deleterious nature of the mutations. Western blot analysis revealed a 62-kDa precursor and 56-kDa mature forms for cells transfected with wild-type and polymorphic R456H enzymes. For cells transfected with mutant enzymes, the reduction in precursor and mature forms suggests an increased degradation of the mutant enzymes. The polymorphic DNA haplotype of the NS gene was analysed in 52 unrelated subjects. All five polymorphisms were in Hardy-Weinberg equilibrium. The strong non-random association among the five polymorphisms suggests little or no recombination in the NS gene.

Adolescent↗
PubMed2002

A role for CCN3 (NOV) in calcium signalling.

AIMS: In animals and humans increased expression of CCN3 (NOV) is detected in tissues where calcium is a key regulator, such as the adrenal gland, central nervous system, bone and cartilage, heart muscle, and kidney. Because the multimodular structure of the CCN proteins strongly suggests that these cell growth regulators are metalloproteins, this study investigated the possible role of CCN3 in ion flux and transport during development, control of cell proliferation, differentiation, and pathobiology. METHODS: The isolation of CCN3 partners was performed by means of the two hybrid system. Yeasts were cotransfected with an HL60 cDNA library fused to the transactivation domain of the GAL4 transcription factor, and with a plasmid expressing CCN3 fused to the DNA binding domain of GAL4. Screening of the recombinant clones selected on the basis of leucine, histidine, and tryptophan prototrophy was performed with a beta-galactosidase assay. After the interaction between CCN3 and its putative partners was checked with a GST (glutathione S-transferase) pull down assay, the positive clones were identified by cloning. To establish whether the CCN3 protein affected calcium ion flux, a dynamic imaging microscopy system was used, which allowed the fluorometric measurement of the intracellular calcium concentration. The proteins used in the assays were GST fused with either CCN3 or CCN2 (CTGF) and GST alone as a control. RESULTS: The two hybrid system identified the S100A4 (mts1) calcium binding protein as a partner of CCN3 and the use of the GST fusion proteins showed that the addition of CCN3 and CCN2 to G59 glioblastoma and SK-N-SH neuroblastoma cells caused a pronounced but transient increase of intracellular calcium, originating from both the entry of extracellular calcium and the mobilisation of intracellular stores. CONCLUSIONS: The interaction of CCN3 with S100A4 may account, in part, for the association of CCN3 with carcinogenesis and its pattern of expression in normal conditions. The increased intracellular calcium concentrations induced by CCN3 and CCN2 both involve different processes, among which voltage independent calcium channels might be of considerable importance in regulating the calcium flux associated with cell growth control, motility, and spreading. These observations assign for the first time a biological function to the CCN3 protein and point out a broader role for the CCN proteins in calcium ion signalling.

Amino Acid Sequence↗
PubMed2001

Heat shock inhibits IL-12 p40 expression through NF-kappa B signalling pathway in murine macrophages.

We report the effect of heat shock on lipopolysaccharide (LPS)-induced interleukin 12 (IL-12) expression. The augmentation of LPS-induced IL-12 p40 mRNA and p70 protein was significantly suppressed in both peritoneal macrophages and RAW264.7 cells after heat shock at 43 degrees C. The binding activity of nuclear factor kappa B (NF-kappa B) was reduced by prior heat shock. LPS did not induce degradation of the inhibitory protein I-kappa B alpha in the shocked cells, which might be a potential mechanism to block NF-kappa B activation. Furthermore, transient transfection assay in RAW264.7 cells demonstrated that LPS-induced activation of DM703 and DM138 (contains NF-kappa B motif) was highly sensitive to heat shock. These data suggest that heat shock influences expression of IL-12 through the I-kappa B/NF-kappa B pathway.

Animals↗
PubMed2001

Highly activated Fgfr3 with the K644M mutation causes prolonged survival in severe dwarf mice.

Several gain-of-function mutations in a receptor tyrosine kinase, fibroblast growth factor receptor 3 (FGFR3), cause dwarfism in humans. Two particularly severe dwarfisms, thanatophoric dysplasia type II (TDII) and severe achondroplasia with developmental delay and acanthosis nigricans (SADDAN), are associated with glutamic acid (E) and methionine (M) substitutions at the K650 residue in the kinase domain. TDII is lethal at birth, whereas most of the SADDAN patients survive the perinatal period. However, FGFR3 with the SADDAN mutation is more activated than FGFR3 with the TDII mutation in vitro. To find out whether the K650M mutation also causes the SADDAN phenotype, we introduced the corresponding point mutation (K644M) into the mouse Fgfr3 gene. Heterozygous mutant mice show a phenotype similar to human SADDAN, e.g. the majority of the SADDAN mice survive the perinatal period. This suggests that the survival of SADDAN patients is indeed attributed to the K650M mutation in FGFR3. The long bone abnormalities in SADDAN mice are milder than the TDII model. In addition, overgrowth of the cartilaginous tissues is observed in the rib cartilage, trachea and nasal septum. The FGF ligand at the low concentration differentially activates Map kinase in primary chondrocyte cultures from wild-type and SADDAN mice. Comparisons of the molecular bases of the phenotypic differences in SADDAN and TDII mice may increase our understanding of the factors that influence the severity in these two related skeletal dysplasias.

Acanthosis Nigricans↗
PubMed2001

A new noninvasive method for evaluation of coronary endothelial function in hypertensive patients based on change in diameter of the left main coronary artery induced by cold pressor test using echocardiography.

BACKGROUND: Coronary endothelial function is frequently studied by measuring the vasodilator response of coronary arteries to acetylcholine or to cold pressor test by invasive quantitative coronary angiography. Because invasive methods have substantial inherent limitations, studies should attempt to evaluate coronary endothelial function noninvasively. HYPOTHESIS: We attempted to evaluate the accuracy of measurement of the percent change in diameter of the left main trunk induced by cold pressor test with two-dimensional (2-D) echocardiography. Furthermore, we applied this method to the evaluation of coronary artery endothelial function in hypertensive patients. METHODS: We measured the left main trunk diameter in 21 subjects (51 +/- 4 years) before and after cold pressor test using quantitative coronary angiography followed immediately by 2-D echocardiography. The accuracy of measurement of the left main trunk diameter and its percent change by echocardiography was evaluated by comparing the values obtained by the two methods. In addition, using echocardiography, we compared left main trunk diameter responses to cold pressor test in 16 hypertensive patients [51 +/- 5 years (mean +/- standard deviation)] and 16 matched healthy subjects (50 +/- 4 years). RESULTS: Although there was only a weak correlation between the absolute values of the left main trunk diameter measured by the two methods (r = 0.61; p = 0.04), a strong correlation was found between the percent change in diameter measured by the two methods (r = 0.93; p = 0.0001). The percent change in diameter of the left main trunk induced by cold pressor test in hypertensive patients (-3.7 +/- 10.6%) was significantly lower than that in control subjects (13.2 +/- 6.8%, p = 0.0001). CONCLUSIONS: Percent change in diameter of the left main trunk induced by cold pressor test can be evaluated accurately using 2-D echocardiography. Our study showed reduced vasodilation or vasoconstriction of the left main trunk after cold pressor test in hypertensive patients compared with healthy subjects, indicating impaired coronary endothelial function in hypertensive patients. The present echocardiographic method is a potentially useful new noninvasive method for evaluating coronary endothelial function.

Adult↗