Biomedical subjects

Ning Kang

Publications and source records attributed to Ning Kang.

24 records · Page 2Linked to original sources

PubMed2003

[Expression of type II collagen gene and structural change in bone tissues of rats with experimental fluorosis].

OBJECTIVE: To investigate the effects of excessive intake of fluoride on the expression of type II collagen gene and types and morphological change of collagen fiber in the bone tissues of rats. METHODS: A rat model with fluorosis was established by adding 221 mg/L of sodium fluoride (NaF) to drinking water for the rats for 15 days, 30 days and two months, respectively. Type II collagen alpha1 (II) cDNA probe was prepared, and cDNA-mRNA in-situ hybridization was employed to detect change in expression of type II collagen mRNA in the bone tissues of rats with excessive intake of fluoride (221 mg/L NaF). Picrosirius-polarization method was used to observe types of collagen and morphology of collagen fiber in the bone tissues. RESULTS: Chondroblasts were found in the femur and other bone tissues of the rats after exposure to fluoride. cDNA-mRNA in-situ hybridization showed that expression of type II collagen gene could be observed in the cytoplasm of chondrocytic lacuna and chondrified bone tissues. mRNA in collagen of chondrocytes of the rib cartilage reached the peak level 15 days after exposure to fluoride, and decreased gradually one month and two months after exposure. Polychromatic type II collagen, breakage of collagen fiber, disorder array and reduced content of type II collagen could be found in the bone tissues with picrosirius-polarization method. CONCLUSIONS: Excessive intake of fluoride could lead to changes in types and structure of collagen (cross-linkage) of bone tissues, which caused expression of type II collagen gene in the chondrified bone tissues and enhanced its expression in the rib cartilage tissues.

Animals↗

PubMed2003

[Cloning of differentially displayed cDNAs involved in NaF-treated osteoblasts].

OBJECTIVE: To explore the effects of excessive fluoride on the gene expression of rat osteoblasts. METHODS: Rat osteoblasts were treated with 2.0 mmol/L of sodium fluoride (NaF) for two weeks in vitro, and difference in the gene expression between the NaF-treated and normal osteoblasts was compared with mRNA differential display (DD-PCR) technique. RESULTS: Among the six differentially expressed gene fragments which had been cloned, expression of the ribosomal protein L5 gene, ATPase Na(+)K(+) transporting beta polypeptide 3 gene, karyopherin alpha 2 gene and cis-Golgi body p28 gene was lower and expression of ubiquitous-conjugating enzyme E2D 3 gene and a newly-discovered gene fragment in this study showed up-regulated in the NaF-treated osteoblasts of the rats. CONCLUSIONS: Expression of genes changed in the osteoblasts after treatment with fluoride for two weeks and most of them associated with synthesis, transportation and processing of protein. It suggested that excessive fluoride could affect the protein synthesis in osteoblasts by changing the expression of the related genes. A novel gene related to excessive fluoride exposure was also found.

Animals↗

PubMed2002

Effects of age and gender on finger coordination in MVC and submaximal force-matching tasks.

The objective of the study is to examine the effects of age and gender on finger coordination. Twelve young (24 +/- 8 yr; 6 men and 6 women) and 12 elderly (75 +/- 5 yr; 6 men and 6 women) subjects performed single-finger maximal contraction [maximal voluntary contraction (MVC)], four-finger MVC, and four-finger ramp force production tasks by pressing on individual force transducers. A drop in the force of individual fingers during four-finger MVC tasks compared with single-finger MVC tasks (force deficit) was larger, whereas unintended force production by other fingers during single-finger MVC tasks (enslaving) was smaller, in elderly than in young subjects and in women than in men. Force deficit was smaller and enslaving was larger in subjects with higher peak force. During the ramp task, the difference between the variance of total force and the sum of variances of individual forces showed a logarithmic relation to the level of total force, across all subject groups. These findings suggest that indexes of finger coordination scale with force-generating capabilities across gender and age groups.

Adult↗

PubMed2002

Finger coordination in persons with Down syndrome: atypical patterns of coordination and the effects of practice.

The study addresses an issue of possible relations between the apparent "clumsiness" of persons with Down syndrome (DS) and changes in indices of finger coordination. We hypothesized that persons with DS would prefer less challenging, safer motor strategies reflected in finger coordination patterns. Maximal single- and multi-finger force production (MVC) tasks and multi-finger tasks that required the production of a controlled time pattern (ramp) of total force were studied. As compared to typical persons, persons with DS showed lower peak forces, lower force deficit (loss of finger force in multi-finger tasks as compared to single-finger tasks), and higher enslaving (involuntary force production by fingers that are not required to produce force). They showed higher variance of total force computed across several trials for ramp tasks. Their total force variance was higher than the sum of the variances of individual finger forces over the ramp duration, while in control participants the relation was opposite during the middle and late thirds of the ramp. Persons with DS practiced force production tasks over 3 days, one group practicing only one of the tasks (the ramp task with all four fingers acting together) while the other group practiced MVC and ramp tasks (variable practice). Practice led to an increase in MVC, force deficit, and enslaving. The relation between the total force variance and the sum of the variances of individual finger forces became closer to the one observed in typical persons. The effects of practice were more pronounced in the variable practice group. We conclude that persons with DS have a deficit in control of both single fingers and multi-finger groups. They use a less challenging, suboptimal strategy of multi-finger coordination which does not take advantage of the possibility of error compensation among the fingers. Practice is an effective way of improving finger coordination in DS, particularly when using variable tasks.

Adolescent↗

PubMed2002

[Homozygous deletion of p16 and p15 genes in laryngeal squamous cell carcinoma].

OBJECTIVE: To assess the relationship of homozygous deletion status of p16 (MTS1/INK4a/CDKN2A), p15(MTS2/INK4b/CDKN2B) genes and laryngeal squamous cell carcinoma(LSCC) progression. METHODS: DNA was extracted from fresh tumors. Homozygous deletion of p16 exon 2(p16E2) in 80 cases of LSCC and p15 exon 2(p15E2) in 67 cases of LSCC were detected by the polymerase chain reaction technique. RESULTS: The p16E2 deletion rate in 80 cases was 12.5%(10/80); the p15E2 deletion rate in 67 cases was 11.94%(8/67); the p16E2 and p15E2 codeletion rate in 67 cases was 5.97%(4/67). CONCLUSION: Homozygous deletion of p16E2 and p15E2 is related with LSCC oncogenesis, and it may play a role to some extent in LSCC malignant progression.

Carcinoma, Squamous Cell↗

PubMed2002

[Study on the silica-induced cytotoxicity and hprt gene mutagenisis in rat lung fibroblasts and alveolar type II epithelial cells].

OBJECTIVE: To explore the differences of the silica-induced inhibition on cellular proliferation and hprt gene mutagenesis between lung fibroblasts and alveolar type II cells. METHODS: The proliferation inhibitive cytotoxicity was detected by MTT (3-[4,5-Dimethylthiazolzyl]-2,5-Diphenyl Tetrazolium Bromide) colorimetric method. Mutation in the hprt gene was screened by culture in the presence of the toxic purine analog, 6-thioguanine (6-TG). RESULTS: Under the same circumstances of silica exposure, alveolar type II cells was more sensitive than lung fibroblasts for proliferation inhibition. The median proliferation inhibition concentration (IC50) of silica on epithelial was 140 micrograms/cm2, whereas IC50 of silica on fibroblasts was 282 micrograms/cm2. At the same doses of silica, the hprt gene mutation frequency in type II cells (84.2 x 10(-6))-156.6 x 10(-6) was statistically higher than that in fibroblasts (67.6 x 10(-6)-114.3 x 10(-6), P < 0.05). CONCLUSION: There were significant differences of both silica-induced cell proliferation inhibition and hprt gene mutation between rat lung fibroblasts and type II epithelial cells. In vitro, cultured rat alveolar type II cells were more sensitive in cytotoxicity and hprt gene mutagenesis to silica dust than lung fibroblasts were.

Animals↗