Biomedical subjects

L L Fu

Publications and source records attributed to L L Fu.

6 recordsLinked to original sources

PubMed2001

Intra-articular hyaluronic acid following knee immobilisation for 6 weeks in rabbits.

Thirty-two mature female New Zealand White rabbits were immobilised in an aluminium splint on one knee, using the contralateral non-treated knee as control. After 6 weeks the splints were removed and the rabbits allowed unrestricted movement. On a random basis, 16 rabbits were given an intra-articular injection of 5 mg in 0.5 ml of hyaluronic acid (HA) in the knee of the immobilised hindlimb at weekly intervals for 6 weeks, starting 1 week after the joint had been remobilised, for a total of six injections. In the other 16 rabbits no further intervention was conducted. At the end of the experiment the rabbits were killed, the area of degenerated joint surface of the distal femur, and water and proteoglycan content were measured, and the articular cartilage stained with haematoxylin and eosin and safranin O. Remobilisation without HA administration resulted in a significantly larger degenerated joint surface area. By the end of the experiment both remobilisation and remobilisation and intra-articular HA injections had produced a greater but non-significant water cartilage content compared to the control side. The average cartilage glycosaminoglycan content of the remobilisation and intra-articular HA injection group was significantly greater than in the remobilisation group. In conclusion, in the rabbits with one knee immobilised for 6 weeks, 6 weeks of remobilisation alone are not sufficient to recover from the moderate articular surface changes produced, and the intra-articular administration of HA may produce a morphologically and biochemically more normal cartilage. More extensive animal and human studies should be performed before the routine use of intra-articular administration of HA following musculoskeletal injuries that required immobilisation can be recommended.

Animals↗

PubMed2000

Geographic clustering of an outer surface protein A mutant of Borrelia burgdorferi. Possible implications of multiple variants for Lyme disease persistence.

DNA sequences encoding full-length outer surface protein (Osp) A were amplified from four joint fluid samples over 4.5 months from a patient with chronic Lyme arthritis, with a variant from wild type only found in sample 3. Rather than a mutation in vivo, these findings suggested a mixed infection in which BORRELIA: containing the wild-type and mutant ospA were waxing and waning in the patient's joint. If so, we reasoned that the mutant should be present in the community. We therefore took the novel epitope resulting from the mutation, expressed as a fusion protein in Escherichia coli, and performed Western blots on 80 high-titred stored sera; however, all except that of our index patient were negative. We then collected 36 stored sera from patients with Lyme disease residing within 10 miles of where the index patient had lived. An additional two sera from this circumscribed area were positive (P = 0.038). These findings show that results from single samples can be misleading, and suggest that the OspAs expressed in force late in Lyme arthritis are the same ones introduced initially into the host. Moreover, they allow a speculative mechanism for disease persistence not previously considered, in which antigenically distinct B. burgdorferi variant proteins present themselves serially to the immune system.

Antigens, Surface↗

PubMed1998

Articular cartilage lesions of the knee following immobilisation or destabilisation for 6 or 12 weeks in rabbits.

Eighty mature female New Zealand White rabbits were sacrificed 6 or 12 weeks after either section of the medial collateral and the anterior cruciate ligaments with removal of the anterior third of the medial meniscus of one knee, or immobilisation of one knee, using the contralateral non-treated knee as the control. The area of degenerated joint surface of the distal femur, and water and proteoglycan content were measured, and the articular cartilage stained using haematoxylin and eosin and safranin O. Destabilisation resulted in a significantly larger time-dependent degenerated joint surface area. Water content significantly increased after 6 weeks with no significant differences between immobilisation and destabilisation. Destabilisation resulted in a significantly greater decrease in proteoglycan content. At 12 weeks, the control knees of the animals undergoing destabilisation showed significant degenerative changes. There were more extensive lesions in destabilisation, while 6 weeks of immobilisation produced moderate degenerative joint disease.

Analysis of Variance↗

PubMed1998

[Involvement of endogenous opioids in cardioprotective effects of ischemic preconditioning in the isolated rat heart].

In the present study, the relationship between the blockade of kappa-opioid receptor and ischemic preconditioning (IP) was examined and the effect of IP and prolonged ischemia on levels of dynorphin A1-13 (Dyn A1-13) in cardiac muscle in isolated perfused rat heart was investigated. The results are as follows: (1) IP reduced the severity of ischemia/reperfusion arrhythmia (P < 0.05) and infarct size (P < 0.01), but had no significant effect on heart rate and coronary flow (P > 0.05); (2) MR2266, kappa opioid receptor antagonist, reduced the severity of ischemia/reperfusion arrhythmia (P < 0.05) and infarct size (P < 0.01), and also enhanced the recovery of coronary flow, but had no significant effect on heart rate (P > 0.05); and (3) prolonged ischemia decreased the levels of Dyn A1-13 (P < 0.05), which was more marked in the unpreconditioned hearts. The results suggest: (1) MR2266 can "mimic" cardioprotective effect of IP in reducing the severity of arrhythmias and limiting infarct size of cardiac muscle; (2) ischemia causes release of endogenous kappa opioids, which can be attenuated by IP; and (3) the cardioprotective effects of IP in rat heart involves endogenous kappa opioids.

Animals↗

PubMed1995

An ospA frame shift, identified from DNA in Lyme arthritis synovial fluid, results in an outer surface protein A that does not bind protective antibodies.

Passive immunization with murine or human Abs to outer surface protein A (OspA) can protect mice against Borrelia burgdorferi, but OspA Abs elicited during natural infection in mice or humans are unable to clear the spirochete from the infected host. To examine Ab binding by OspA during the course of human infection, we amplified the operon encoding full-length ospA and ospB from synovial fluids of a patient with chronic Lyme arthritis, the first such recoveries from human material, at four separate time points over 4.5 mo, and expressed OspA in Escherichia coli. OspA mAbs that passively protected mice from infection did not bind one of the expressed OspAs, because of a deletion in ospA that resulted in a frame shift and premature stop codon near the carboxyl terminus. However, expressed OspA from a later synovial fluid sample did not contain this deletion. Thus, although altered forms of OspA, which potentially can influence host immune effectiveness, do occur in the human host, they cannot be the only factors responsible for microbial persistence.

Adolescent↗

PubMedDate not supplied

Partial patellectomy induces a decrease in the proteoglycan content in the remaining patellar articular cartilage. An experimental study in rabbits.

We studied the alterations and distribution of the proteoglycan (PG) content of the remaining patellar articular cartilage after unilateral partial patellectomy in 13 rabbits. Sagittal sections of the patella were prepared and stained with Safranin O for quantification of changes in the PG content of the patellar articular cartilage using a commercially available imaging analysis system. Our findings suggest that partial patellectomy results in a decreased PG content in the remaining patellar articular cartilage. In addition, the postoperative development of metaplasia in the scar tissue next to the healing interface may represent a compensatory response, which could prevent a further reduction in the PG content and hence the development of osteoarthritis in the remaining patellar articular cartilage.

Animals↗