Biomedical subjects

Ling Qin

Publications and source records attributed to Ling Qin.

71 records · Page 4Linked to original sources

PubMed2004

Characteristics of long bone DXA reference data in Hong Kong Chinese.

With the increasing number of geriatric long bone fractures, the establishment of long bone reference BMD data is desirable for the accurate diagnosis of osteoporosis, study of fracture mechanics, implant design, and indications for augmentation of fracture fixation with biomaterials. We report the normal reference bone mineral density (BMD) and bone mineral content (BMC) at three femoral sites (proximal, diaphyseal, and distal) in 106 male and 93 female Hong Kong Chinese aged 12 to 80, measured with dual-energy X-ray absorptiometry (DXA). The length and width of the femur were also measured. The results suggest that males reached peak bone mass earlier than females and the value was also higher in all measured sites. After reaching the peak bone mass, bones lost BMD faster in females. The age-related annual bone loss (in BMD) calculated with a regression model in female subjects were, on average, 3.3, 4.0, and 3.0 times higher than those in males at the diaphyseal, proximal, and distal regions, respectively. The decrease in BMD and BMC occurred slightly earlier in the proximal and distal regions than the diaphysis in both sexes. The male femur was significantly longer than that of the female in all age groups after 20 yr of age and remained unchanged with advancing age. The femoral width in females showed an increasing trend from adolescence. Our study provides reference data for the changes in diaphyseal BMC and BMD associated with aging. The age-related changes in the femoral diameter in females might attenuate the negative impact on fracture risk as a result of decreasing BMD with age.

Absorptiometry, Photon↗

PubMed2004

[A molecular-epidemiologic study on TEM-1 genes of Neisseria gonorrhoeae in Wuxi area].

OBJECTIVE: In order to study the epidemiology of TEM-1 genes of Neisseria gonorrhoeae (Ng) in Wuxi area. METHODS: In the light from foreign literature that positive Ng strains of beta-lactamase contain plasmid sequences of TEM-1 genes, heminested PCR for TME-1 genes of Ng detection was self-designed. Ng of 195 strains were detected, that were isolated in Wuxi area from Jan to the Oct, 2002. RESULTS: There were 138 TEM-1 genes positive in 195 isolated strains with a positive rate of 70.8%. There was one case of heminested PCR product of TEM-1 genes which showed the homogeneity was 99% in Wuxi area, when comparing with pFA7 sequences of positive Ng plasmid of beta-lactase from register GenBank. CONCLUSION: Data showed that the Ng strains with TEM-1 genes were the prevalent ones in Wuxi area.

China↗

PubMed2004

[Study on the molecular epidemiology of beta-lactamase TEM gene in isolated Streptococcus pneumoniae].

OBJECTIVE: To investigate the beta-lactamase TEM gene of isolated Streptococcus pneumoniae (Sp) in Suzhou area. METHODS: Twenty-three strains of Sp were collected from respiratory tract secretions of children with respiratory diseases in Nov 2002 to Apr 2003 at Children's Hospital of Suzhou University (reference strain ATCC49619) to build TEM polymerase chain reaction (PCR) system (reference strain E. coli. 9-j53R1 with TEM gene) TEM gene of 23 strains was detected to comparo the sequences with published TEM gene sequences in GenBank for analyzing TEM gene model. RESULTS: Twenty-one strains had TEM gene with a positive rate of 91.3% (21/23). TEM-129 gene were confirmed from No.17 (SR017, penicillin resistance) TEM sequence. New discovered TEM-129 sequence had a modification (ATG[M]-->ATA[I]) at No.182 code and published (GenBank: www.ncbi.nlm.nih.gov/nucleotide, AY452662). TEM-1 genes were confirmed from other TEM sequences. New discovered TEM-1 gene of isolated Sp had been published (GenBank: www.ncbi.nlm.nih.gov/nucleotide, AY392531) too. CONCLUSION: Isolated Sp had TEM gene (TEM-129, EM-1 genotype) with a positive rate of 91.3%. The result enriched the understanding of isolated Sp with penicillin resistance.

Base Sequence↗

PubMed2003

The effects of verbascoside on plasma lipid peroxidation level and erythrocyte membrane fluidity during immobilization in rabbits: a time course study.

We studied the changes in the level of plasma lipid peroxidation indicated by malondialdehyde (MDA) level and erythrocyte membrane fluidity expressed by the value of order parameter (S) during single hindlimb immobilization of 21 days using thiobarbituric acid - reactive substances method and spin label electron spin resonance method, respectively. The impacts of verbascoside that has been proved its antioxidative activity on the measured parameters were examined. 11 New Zealand white rabbits were immobilized and divided into two groups. The rabbits in the verbascoside group were administrated with 0.8 mg/kg of verbascoside twice a day orally throughout the immobilization. The rabbits in the placebo group were treated with normal saline. In placebo group, the results showed that the level of MDA significantly increased on day 3, peaked on day 7, and was still significantly higher on day 14 of immobilization, compared with the value measured before immobilization. The value of S reached the highest on day 7 and subsequently lowered but still higher on day 14 than those measured before immobilization. Compared with placebo group, there were lower MDA level (P < 0.05, 0.001, and 0.05 for days 3, 7, and 14, respectively) and higher erythrocyte membrane fluidity (P < 0.05, 0.001, and 0.001 for days 3, 7, and 14, respectively) in verbascoside group. The data indicated that immobilization caused temporal changes of increase in plasma lipid peroxidation and decrease in erythrocyte membrane fluidity. Verbascoside might have the effects to moderate oxidative stress and erythrocyte membrane fluidity during immobilization.

Administration, Oral↗

PubMed2003

Gene expression profiles and transcription factors involved in parathyroid hormone signaling in osteoblasts revealed by microarray and bioinformatics.

Parathyroid hormone (PTH) binds to its receptor PTH1R (parathyroid hormone 1 receptor) in osteoblastic cells to regulate bone remodeling and calcium homeostasis. While prolonged exposure to PTH causes increased bone resorption, intermittent injections of PTH have an anabolic effect on bone. The molecular mechanisms regulating these processes are still largely unknown. Here, we present our results on gene expression profile changes in the PTH-treated osteoblastic cell line, UMR 106-01, using DNA microarray analysis. A total of 125 known genes and 30 unknown expressed sequence tags (ESTs) were found to have at least 2-fold expression changes after PTH treatment at 4, 12, and 24 h. 14 genes were previously known to be PTH-regulated but many were unknown to be regulated by PTH prior to our experiments. Real-time reverse transcriptase-PCR confirmed that 90 and 50% of the genes are regulated more than 2-fold by PTH in UMR 106-01 and rat primary osteoblastic cells, respectively. Most genes belong to the following protein families: hormones, growth factors, and receptors; signal transduction pathway proteins; transcription factors; proteases; metabolic enzymes; structural and matrix proteins; transporters; etc. These results provide a comprehensive and deeper knowledge about PTH regulation of osteoblastic gene expression. Next, we designed a computational method to extract information about transcription factors likely involved in regulating these genes. These factors include those previously known to be involved in PTH signaling (AP-1 and the cAMP response element-binding protein), those that were identified by microarray data (C/EBP), and some novel transcription factors (AP-2, AP-4, SP1, FoxD3, etc.). Our results suggest that a reliable bioinformatics approach can be easily applied for other systems.

Animals↗

PubMed2003

Comparative promoter analysis and its application in analysis of PTH-regulated gene expression.

Taking advantage of the "working draft" of the human genome and the MIT shotgun assembly of the mouse genome, we performed a comparative promoter analysis of human RefSeq mRNA (sequences from GenBank's RefSeq database). By combining this analysis with a transcription factor (TF) binding site analysis using a TRANSFAC position weight matrix (PWM) search, 86% of non-specific TF sites were removed. Using a set of genes that are regulated by parathyroid hormone (PTH), a statistical analysis was performed on the conserved TF binding sites among a set of eight human and mouse genes. From among the eight genes tested, we obtained a set of 31 TFs, suggesting possible roles for associated genes in PTH-mediated pathways. All three known PTH-responsive TFs (AP1, RUNX2, CREB) were correctly predicted by this analysis as well as two other potential TFs (VDR and CEBP Delta). Additionally, a model was made to describe the TF site characteristic module of PTH-regulated genes. This model was then used to search all human RefSeq gene promoters with established human-mouse ortholog relationships to identify other PTH-regulated genes. This comparative approach combined with statistical analysis proved to be sufficiently specific to decipher critical TFs involved in PTH-regulated pathways.

Algorithms↗

PubMed2003

pQCT bone strength index may serve as a better predictor than bone mineral density for long bone breaking strength.

Bone mineral density (BMD) is commonly used to predict osteoporotic fracture risk without considering the geometry of the bone. However, geometric parameters are also important in determination of bone strength. An index including both material and geometric properties may be therefore more relevant in prediction of fracture risk. We studied the correlation between parameters measured by noninvasive peripheral quantitative computed tomography (pQCT) and bone bending strength of the diaphysis of 45 fresh goat humeri and 27 femora. Multislice pQCT was used for measuring volumetric diaphyseal cortical BMD, total BMD, diaphyseal and cortical cross-sectional area (CSA), and cross-sectional moment of inertia (CSMI) and their derived bone strength indices (BSIs), including BSI(CSMI) (cortical BMD x CSMI) and BSI(CSA) (cortical BMD x cortical CSA). Conventional dual-energy absorptiometry (DXA) was also conducted to measure areal BMD of diaphysis for comparison. Ultimate fracture load was obtained via three-point bending test. Results showed that for femora, fracture load was correlated better with BSI(CSA) ( r = 0.697, P < 0.001) than cortical BMD ( r = 0.304, P > 0.05) and total BMD ( r = 0.387, P > 0.05) measured using pQCT and areal BMD ( r = 0.612, P < 0.001) measured using DXA. For humeri, fracture load was also correlated with BSI(CSA) ( r = 0.579, P < 0.001) but not with other pQCT parameters including cortical BMD and total BMD ( r = 0.282 and 0.305, respectively; P > 0.05, both). The best correlation was found with areal BMD measured by DXA ( r = 0.760, P < 0.001). In conclusion, pQCT noninvasive BSI(CSA) derived from cortical BMD (material) and its cortical CSA (bone geometry or distribution) may serve as an important noninvasive index for predicting long bone bending strength. The bending strength was also predicted by bone mass (areal BMD) measured by DXA, an integration of bone mineral and geometry. Further clinical studies are needed to validate the predictive value of BSI in long bone osteoporotic fracture.

Animals↗

PubMed2003

Time course of tonal frequency-response-area of primary auditory cortex neurons in alert cats.

Cells in the A1 auditory cortex of alert animals show various response time-courses during pure-tone stimuli: tonic, phasic-tonic, and phasic. Previously the time course of the spike firing rates was examined at a characteristic frequency (CF) or in a range of frequencies including CF. We investigated time-course of the frequency-response-area (FRA) during pure-tone stimuli in A1 cells of alert cats. The short rise/fall time (0.1-2 ms) and long stimulus duration (0.5 s) was used for investigation of the time course. FRA changed with time drastically in the phasic cells, mildly in the phasic-tonic cells, but not in the tonic cells. The best-response frequency (BF) within FRA was constant throughout the stimulus duration in the tonic and phasic-tonic cells, but was difficult to define in the phasic cells. The phasic firing properties of the phasic cells were preserved even during the bandnoise stimuli at various bandwidth and spectral locations. The variability of FRA time-course between cell types may play a role for analyzing auditory spectral cues that vary with a wide range of time constant.

Acoustic Stimulation↗

PubMed2003

Healing of bone-tendon junction in a bone trough: a goat partial patellectomy model.

Bone-tendon junction healing in a bone trough was investigated in a goat partial patellectomy model. Histologic evaluation and biomechanical tests were done at 6, 12, and 24 weeks. Irregular fibrous tissue seen at the healing bone-tendon junction at 6 weeks gradually assumed longitudinal alignment and remodeled toward a direct bone-tendon junction. Type III collagen deposition was diffuse at 6 weeks, but became localized to the healing interface at 12 weeks. Thickness of newly formed bone increased progressively with time. Bridging collagen fibers were formed at the junction, with fibrochondrocytic cells and a basophilic tidemark detected at 24 weeks. The trabecular line remained discontinuous and there was no safranin O uptake. Most specimens failed at the junctions under tensile loads. The ultimate failure stress increased from 4.78 +/- 0.50 N/mm2 at 6 weeks to 7.99 +/- 0.33 N/mm2 at 24 weeks (mean +/- standard error of the mean), only reaching 15% of normal. Cartilage from the articular cut surface extended into the healing interface, later forming an area of fibrocartilage with densely packed collagen fibers aligned along the direction of force, containing proteoglycans. Cartilage may enhance restoration of a transition zone in bone-tendon junction healing. The sequence of events outlined formed a basis to guide clinical practice regarding bone-tendon junction reattachment.

Animals↗

PubMed2003

Cysteine-scanning analysis of the dimerization domain of EnvZ, an osmosensing histidine kinase.

EnvZ and OmpR are a transmembrane sensor and its cognate response regulator, respectively, regulating the transcription of porin genes in response to medium osmolarity in Escherichia coli. The cytoplasmic domain of EnvZ (EnvZc) possesses both kinase and phosphatase activities and can be dissected into two functional domains, A and B. Here, we performed a cysteine-scanning analysis of domain A, a 67-residue central dimerization and phosphatase domain containing His-243 as the phosphorylation site, and we examined the effects of the cysteine substitution mutations on the enzymatic activities of domain A. The substitution mutations were made at 31 residues, from which 24 mutant domain A proteins were biochemically characterized. From the analysis of the phosphatase activity of purified mutant proteins, it was found that there are two regions in domain A which are important for this activity. Cysteine mutations in these regions dramatically reduce or completely abolish the phosphatase activity of domain A. The mutations that have the most-severe effects on domain A phosphatase activity also significantly reduce the phosphatase activity of EnvZc containing the same mutation. Using an in vitro complementation system with EnvZc(H243V), these cysteine mutants were further characterized for their autophosphorylation activities as well as their phosphotransfer activities. The results indicate that some mutations are specific either for the phosphatase activity or for the kinase activity.

Amino Acid Sequence↗

PubMed2002

Tonal response patterns of primary auditory cortex neurons in alert cats.

The firing rates of primary auditory cortex (A1) neurons are known to be modulated only at the onset, offset, and change of a tonal stimulus in anesthetized animals. The tonal response pattern has been rarely investigated in alert animals. We investigated the time-course of A1 neuron responses to a steady tonal stimulus in alert cats. We found four types of firing responses based on statistical evaluation of the time course of the firing rate. The tonic cells (38 cells) showed a significant (P<0.05) firing increase throughout the stimulus period after a relatively long latency (mean, 25.3 ms) with little tendency of adaptation. The phasic-tonic cells (22 cells) showed a significant firing increase throughout the stimulus period after a medium latency (19.8 ms) with tendency of adaptation to less than a half of the maximum excitation level. Phasic cells (15 cells) responded, after a short latency (10.2 ms), at onset and offset of the stimuli. The unresponsive cells (26 cells) did not show a significant firing increase during stimuli. The findings suggest that there is a functional difference between each type of cells: the tonic cells encode information of static auditory signals in their firing rates; the phasic-tonic cells, of the changing auditory signal during the stimulus period; and the phasic cells, of rapid change of the auditory signal at onset and offset.

Acoustic Stimulation↗

PubMed2002

Ultrasound detection of trypsin-treated articular cartilage: its association with cartilaginous proteoglycans assessed by histological and biochemical methods.

We studied the correlation between histological imaging quantification and the biochemical assessment of proteoglycan (PG) content in articular cartilage in vitro, which served as a basis for the validation of ultrasound detection as a noninvasive tool in the assessment of PG changes in full-thickness articular cartilage. Articular cartilage of 14 intact fresh bovine femoral condyles was used for trypsin digestion. Full-thickness articular cartilage cylinders, 3 mm in diameter, were harvested at time intervals of 0.5, 1, 2, and 3 h after trypsin digestion. Each cartilage cylinder was then cut into two equal parts for either histomorphometric quantification of the PG area fraction stained with Safranine O or conventional biochemical assessment of uronic acid content. In addition, five fresh mature bovine patellae were used for the validation of an ultrasound compression system developed for testing the potential layered biomechanical properties of articular cartilage, including the equilibrium compressive modulus, i.e., the slope of the linear regression of the equilibrium stress-strain curve. Results showed that PG content in the articular cartilage was significantly decreased with increasing time of trypsin digestion, both histologically and biochemically, with a significant correlation of r = 0.502 ( P < 0.001). Ultrasound measurements demonstrated differences in the equilibrium compressive moduli of the digested zone, the undigested zone, and the entire articular cartilage layer, as well as a characteristically large ultrasound reflection signal detected in the interface of the trypsin digestion front of articular cartilage. The results of this study suggested that the histomorphometric quantification of PG content could be used to reflect not only PG quantity but also its spatial distribution; also, the ultrasound compression system might have potential for the non-invasive detection of pathological changes in articular cartilage.

Animals↗

PubMed2002

Critical spectral regions for vowel identification.

The first two formant frequencies (F1 and F2) are the cues important for vowel identification. In the categorization of the naturally spoken vowels, however, there are overlaps among the vowels in the F1 and F2 plane. The fundamental frequency (F0), the third formant frequency (F3) and the spectral envelope have been proposed as additional cues. In the present study, to investigate the spectral regions essential for the vowel identification, untrained subjects performed the forced-choice identification task in response to Japanese isolated vowels (/a, o, u, e, i/), in which some spectral regions were deleted. Minimum spectral regions needed for correct vowel identification were the two regions including F1 and F2 (the first and fourth in the quadrisected F1-F2 regions in Bark scale). This was true even when phonetically different vowels had a similar combination of F1 and F2 frequency components. F0 and F3 cues were not necessarily needed. It is concluded that the relative importance in the spectral region is not equivalent, but weighted on the two critical spectral regions. The auditory system may identify the vowels by analyzing the information of the spectral shapes and the formant frequencies (F1 and F2) in these critical spectral regions.

Female↗

PubMed2002

A comparative study of bone to bone repair and bone to tendon healing in patella-patellar tendon complex in rabbits.

OBJECTIVES: To study the healing quality of bone to bone and bone to tendon repair in a patella-patellar tendon complex. DESIGN: In vivo animal experiment in 60 mature 32-week-old female rabbits. BACKGROUND: Injuries of patella-patellar tendon complex are not uncommon. However, no studies are available to compare the healing quality between bone to bone and bone to tendon surgical reconstructions used for repair of patella-patellar tendon complex. METHODS: A standard transverse osteotomy was performed at the distal one-third of patella of one hindlimb. Both patellar fragments were reattached for bone to bone group while the patellar tendon was reattached to the remaining patella after removing the distal one-third of patella for bone to tendon group. Patella-patellar tendon complex was harvested at 8, 12 and 24 weeks postoperatively for biomechanical and histological evaluations, with n=8 and n=2 at each healing time points in both groups. The contralateral knee served as a control. RESULTS: No significant differences in the failure loads were found between two groups. However, greater ultimate stress was found in bone to bone group as compared with bone to tendon group at week 8 and 24 (both P<0.05). On average, the ultimate stress of the bone to tendon and bone to bone group only reached 20.6(4.2)% and 28.6(6.7)% of the control values at week 24, respectively. The discrepancy between findings in failure load and failure stress might be explained by an overall larger cross-sectional area of the healing interface in bone to tendon group as compared with bone to bone group. Histology revealed that the bone to bone healing was via endochondral ossification at the healing interface. In bone to tendon group, extensive scar tissue was formed to overbridge the healing interface and remodeled with healing over time. The structural integration at the tendon and bony healing interface was poor and no typical intermitted fibrocartilage zone as seen in normal bone to tendon junction was formed. CONCLUSION: Failure load of bone to bone and bone to tendon healing interface did not differ during repair of patella-patellar tendon complex. However, the healing interface of bone to bone repair in terms of material properties as reflected by failure stress was superior to that of the bone to tendon healing. RELEVANCE: The findings of this experimental study may suggest that the anatomical reconstruction of patella-patellar tendon complex injury may be the primary concern in decision making for selecting either bone to bone or bone to tendon repair. However whenever possible, to initial fracture (bone-to-bone) fixation for ensuring better and predictable repair at the healing interface.

Analysis of Variance↗

PubMed2002

Formation of the stoichiometric complex of EnvZ, a histidine kinase, with its response regulator, OmpR.

EnvZ, a histidine kinase, and its cognate response regulator OmpR of Escherichia coli are responsible for adaptation to external osmotic changes by regulating the levels of the outer membrane porin proteins, OmpF and OmpC. The osmosensor, EnvZ, has dual enzymatic functions with OmpR kinase and OmpR-P phosphatase. Here, we demonstrate that the cytoplasmic kinase domain of EnvZ (EnvZc) and OmpR are able to form a 1:1 complex detected by native PAGE. This indicates that two OmpR molecules can bind to one EnvZc dimer. As this 1:1 EnvZc/OmpR complex is formed even in the presence of a large excess of EnvZc, OmpR binding to EnvZc is co-operative. The complex formation is also observed between EnvZc and phosphorylated OmpR for the phosphatase reaction. OmpR-P bound to EnvZc was readily released upon the addition of OmpR, indicating that OmpR and OmpR-P can compete for the binding to EnvZ. On the basis of these results, a model is discussed to explain how cellular OmpR-P concentrations are regulated in response to medium osmolarity.

Adenosine Triphosphate↗

PubMed2002

Regular Tai Chi Chuan exercise may retard bone loss in postmenopausal women: A case-control study.

OBJECTIVE: To evaluate the potential benefits of regular Tai Chi Chuan exercise on the weight-bearing bones of postmenopausal women. DESIGN: Case-control study. SETTING: University medical school in Hong Kong. PARTICIPANTS: Postmenopausal women (age range, 50-59y), including 17 self-selected regular Tai Chi Chuan exercisers (TCE) with over 4 years of regular exercise, and 17 age- and gender-matched nonexercising controls (CON). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Bone mineral density (BMD) in the lumbar spine and proximal femur was measured at baseline and at follow-up 12 months later by using dual-energy x-ray absorptiometry (DXA) and in the distal tibia using multislice peripheral quantitative computed tomography (pQCT). RESULTS: Baseline results showed that the TCE group had significantly higher BMD (10.1%-14.8%, all P<.05) than the CON group in the lumbar spine, proximal femur, and the ultradistal tibia. The follow-up measurements showed generalized bone loss in both groups. Although both DXA and pQCT measurements revealed decelerated rates of bone loss in the TCE group, only the more sensitive pQCT showed significantly reduced rate of bone loss in trabecular BMD of the ultradistal tibia (TCE vs CON: -1.10%+/-1.26% vs -2.18%+/-1.60%, P<.05) and of cortical BMD of the distal tibial diaphysis (TCE vs CON: -0.90%+/-1.36% vs -1.86%+/-0.93%, P<.05). CONCLUSION: This is the first case-control study to show that regular Tai Chi Chuan exercise may help retard bone loss in the weight-bearing bones of postmenopausal women.

Bone Density↗

PubMed2002

Immobilization-induced changes in erythrocyte membrane fluidity in rabbits: a spin-label electron spin resonance study.

It has been shown that many diseases are linked to abnormalities of the erythrocyte membrane. This study observed the changes in erythrocyte membrane fluidity during an immobilization period of 21 days. The right hindlimbs of male adult New Zealand white rabbits were immobilized for 21 days. Blood samples were collected and heparinized prior to immobilization and on days 1, 3, 7, 14, and 21 of immobilization. The membrane fluidity of erythrocytes was measured by spin-label electron spin resonance (ESR). The membrane fluidity was expressed by the value of order parameter (S). The results showed a significant increase of S on days 7 and 14 of immobilization (p <0.01). The highest value of S was found on day 7 of immobilization; thereafter, S gradually declined. Compared with the value measured before immobilization, there was no significant difference in the value of S on day 21. The results show that immobilization significantly affected erythrocyte membrane fluidity, indicating a systemic and temporal response ofthe immobilized body. This study is the first to document the time-course of changes in erythrocyte membrane fluidity in rabbits with single hindlimb immobilization during 21 days. These results may be helpful in studying the pathophysiology of immobilization.

Animals↗