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Biomedical subjects

Q Lai

Publications and source records attributed to Q Lai.

13 recordsLinked to original sources
PubMed2001

Long-term neuroprotective effect of inhibiting poly(ADP-ribose) polymerase in rats with middle cerebral artery occlusion using a behavioral assessment.

Poly(ADP-ribose) polymerase (PARP) can initiate an energy-consuming and inefficient repair cycle following cerebral ischemia/reperfusion by transferring ADP ribose units to nuclear proteins eventually leading to cellular dysfunction and neuronal death. 3-Aminobenzamide (3-AB) is a selective inhibitor of PARP that can significantly reduce brain damage after focal ischemia in rats and displays a low toxicity in vivo. The goals of this study were to determine if inhibiting PARP with 3-AB has a long-term neuroprotective effect and if functional outcome improves in rats following focal ischemia and treatment with 3-AB. Focal ischemia was induced by a 2-h occlusion of the middle cerebral artery (MCA), using an intraluminal filament. Motor functions were evaluated from 5 to 28 days after reperfusion in four groups of rats: stroke without treatment; stroke treated with 3-AB at doses of 15 mg/kg, stroke treated with 3-AB at doses of 55 mg/kg; and the non-ischemic control rats. Functional behaviors were tested by a series of motor function tasks (foot placing, parallel bar crossing, rope and ladder climbing), as well as a neurological examination. Infarct volume of stroke brain in the same rat was determined by Nissl staining 28 days after surgery. Comparison of the untreated stroke group (n=11) and the treated stroke groups indicates that impairment of motor function was significantly (P<0.001) reduced by administration of 3-AB at doses of 15 mg/kg (n=9) or 55 mg/kg (n=10). Neurological outcome was also improved significantly (P<0.001). Infarct volume was significantly (P<0.01) reduced in both treated groups. Long-term neuroprotection following ischemia/reperfusion injury to the brain can be obtained by administration of a PARP inhibitor. The motor tests employed in this study can be used as sensitive, objective and reproducible measurements of functional impairment in rats following an ischemic stroke.

Animals↗
PubMed2001

Consistent and variable practice conditions: effects on relative and absolute timing.

The authors conducted the present experiments to resolve the discrepancy between studies in which relative-timing learning has been found to be enhanced by consistent practice conditions and contextual interference experiments in which relative-timing learning has been found to be enhanced more by random practice than by blocked practice. There were 40 participants in Experiment 1 and 48 in Experiment 2. The results of Experiment 1 extended previous findings: The learning of the relative-timing pattern was systematically enhanced by the degree to which the practice conditions promoted movement consistency (constant > blocked > serial > random). Experiment 2 provided evidence that the discrepancy between the relative-timing effects in the 2 groups of studies was a product of the way in which relative-timing goals and feedback were presented. When the feedback was presented as segment times, random practice resulted in generally more stable relative-timing patterns during acquisition than blocked practice did. Thus, in both experiments, the learning of the relative-timing pattern was enhanced by more stable relative-timing conditions during acquisition. Absolute-timing learning, as indexed by the transfer tests, was enhanced by serial or random practice as compared with constant or blocked practice, and was relatively unaffected by feedback conditions directed at the relative-timing pattern. In terms of motor programming theory, those findings are taken as additional evidence for the disassociation of memories supporting generalized motor program (GMP) performance, as indexed by relative timing, and parameter performance, as indexed by absolute timing.

Computers↗
PubMed2001

Impaired motor learning in children with hydrocephalus.

Hydrocephalic (n = 19) and normal (n = 20) children in two age groups (averaged at 10 and 14 years old) were asked to learn 5 predetermined timing rhythm interval tasks (including timing duration and relative timing pattern) by pressing keys on a computer keyboard. In the acquisition phase, visual and auditory goal timing intervals, as well as visualized feedback were presented to all participants before and after their key presses, respectively. A retention test without the auditory information and visualized feedback was administered 1 day later. By using the computerized timing test, we demonstrated in this study that the hydrocephalic group had significantly (ANOVA analysis) increased relative timing errors; this function depends on the formation of an internal model or a motor program related to long-term memory disorders. These findings could lead to the formulation of training procedures with simplified movements that may help hydrocephalic children improve their motor skill learning.

Adolescent↗
PubMed2000

Optimizing generalized motor program and parameter learning.

Two experiments examined generalized motor program (GMP) and parameter learning. Experiment 1 examined the effects of bandwidth knowledge of results (KR) about relative timing in constant and variable practice. The purpose was to determine if movement stability created by the bandwidth manipulation is associated with increased GMP learning and if bandwidth KR interacts with constant and variable practice. Participants were asked to depress four keys sequentially, using the same relative timing structure. Constant practice had one absolute timing requirement, whereas variable practice had three different absolute timing requirements. The results indicated that GMP learning was enhanced by constant practice (independent of the bandwidth KR condition) and by bandwidth KR, when variable practice was used. The findings suggest practice conditions (bandwidth KR, constant practice) that increase movement stability during practice enhance GMP learning. Parameter learning (during transfer), however, was enhanced by variable practice. Experiment 2 attempted to determine how constant and variable practice conditions could be combined to enhance both GMP and parameter learning. The results indicated that developing a stable GMP early in practice--by providing learners with constant practice early in practice--and refining parameter learning later in practice--by providing them with variable practice late in practice--were effective for both GMP and parameter learning. This suggests a hierarchy in the development of programmed actions with a stable GMP being a requisite for developing an effective and stable parameter rule.

Adult↗
PubMed2000

Effects of modeled auditory information on a sequential timing task.

The purposes of the present experiment were to determine (a) whether an auditory model enhanced relative or absolute timing, (b) the extent to which the reduced frequency presentation of the auditory model resulted in enhanced retention, and (c) the degree to which executing the timing sequence was independent of the role of the effectors in carrying out the movement sequence. Participants (N = 45) were asked to alternately press two keys on a computer keyboard in an attempt to match the goal intervals presented on the computer monitor. Groups differed in terms of the frequency with which an auditory model (100, 50, or 0%) was presented. The results indicated that the auditory model (100% or 50% groups) enhanced relative timing performance and learning but not the learning of absolute timing. In addition, the 50% group did not appear to become dependent on the auditory model. However, significant decrements in performance were seen for the 100% group when the model was withdrawn. Last, participants were able to execute the timing sequences equally well when they reversed the hand used to execute the timing sequence. This was interpreted as strong evidence for the effector independence (Schmidt, 1975, 1988) and modularity of the timing sequence (Keele, Davidson, & Hayes, 1998).

Female↗
PubMed1999

The role of reduced frequency of knowledge of results during constant practice.

Two experiments were conducted to further examine the effects of reduced knowledge of results (KR) frequency on the learning of motor skills during constant practice. In Experiment 1, participants in five KR conditions (100% KR, 50% KR-fade, 50% KR-reverse fade, 50% KR-alternative, and 50% KR-random) practiced a movement timing task. In Experiment 2, participants in two KR conditions (100% KR and 50% KR-fade) practiced a waveform reproduction task. The results of both experiments failed to indicate that reduced KR frequency was more effective in promoting learning than the 100% KR conditions. The present study adds to the increasing number of experiments that do not find a benefit of reduced KR frequency on learning in constant practice.

Adult↗
PubMed1999

Evaluation of porous collagen membrane in guided tissue regeneration.

Porous collagen membrane was prepared with collagen protein, which was extracted from bovine tendon by enzyme digestion, by freeze-drying method. The animal, clinical experiments of the membrane used in artificial dental implant system were studied. In the animal experiments, pure titanium spiral implants, which were prepared according to Adell etc. method, were implanted in the mandibular dental alveus of adult hybrid dog and covered with collagen membrane. Then the animals were killed after 4, 18 weeks individually. In the clinical research, the implants (phi 3.3 mm) were used in 33 patients of different age groups. The implant was put on the buccal lateral deficiency of implantation cavity wall, and covered with collagen membrane on the buccal lateral, then observed after 3, 6 months individually. The results of animal experiments proved the collagen membrane could guide osseous tissue regeneration around the bone integral implant which was implanted in the fresh tooth extraction fossa, be helpful to repair the fissural bone deficiency produced when implanted the implant, increase the bone content around the implant significantly, and improve the structure of new bone to a certain extent. The results of clinical research proved that collagen membrane was used in the patients with density deficiency, irregularity of alveolar ridge, or artificial dental of shorter tooth extraction, could significantly improved the bone density of artificial implant's shoulder.

Adult↗
PubMed1999

[Expression of metastasis suppressor gene nm23-H1 in oral squamous cell carcinoma and its relation to tumor prognosis].

OBJECTIVE: To study the relation between the expression level of nm23-H1 protein and prognosis of oral squamous cell carcinoma (OSCC). METHODS: The expression of nm23-H1 protein in 75 cases of OSCC, 27 cases of oral mucosa, 9 cases of cervical lymph-node metastases by immunohistochemical technique (SABC), and the relation between nm23-H1 protein expression level and prognosis of OSCC was evaluated by chi-test and single-factor, multi-factor Cox proportional hazards regression model analysis. RESULTS: These immunoreactivities of nm23-H1 protein were mostly in the cytoplasm of tumor and epithelial cells. There was a significant difference of nm23-H1 protein expression level between three-year survival and seven-year survival group (P < 0.05), and there was a relation between nm23-H1 protein expression level and prognosis of OSCC in single-factor Cox analysis. But no relation was found between nm23-H1 protein expression level and prognosis in multi-factor Cox analysis. CONCLUSION: nm23-H1 protein expression level was probably not a valuable predictor of OSCC patients' prognosis. It may indirectly affect OSCC prognosis through its effect on OSCC metastasis.

Carcinoma, Squamous Cell↗
PubMed1996

[Expression of p53 gene in oral squamous cell carcinoma and its relations with clinical and pathological parameters and prognosis of patients].

One hundred and eleven cases of oral squamous cell carcinoma (OSCC) were examined for overexpression of p53 protein by using immunohistochemical technique. Association of p53 protein overexpression with clinical and pathological parameters as well as prognosis of patients were also analyzed, p53 protein overexpression was commonly observed (69.4%) in the OSCC patients and might be used as a marker of carcinogenesis of OSCC. The level of p53 protein overexpression was correlated with the decreased three and/or five-year survival rate of OSCC. The presence of p53 was not correlated with patient's sex and age, site and size of tumor, degree of differentiation, node status or clinical stage of OSCC. Single factor COX proportional hazards regression model analysis indicated that there was no significant relationship between p53 overexpression and prognosis of OSCC. Multivariable COX model analysis failed to establish effective life function or risk rate function. This showed that all the parameters analyzed in this study as well as p53 overexpression were not significant or effective risk factors to predict prognosis of OSCC patients.

Adult↗
PubMed1995

Expression of p53 gene in oral squamous cell carcinoma and its relation with clinical and pathological parameters and prognosis of patients.

One hundred and eleven cases of oral squamous cell carcinoma (OSCC) were examined for overexpression of p53 protein by using immunohistochemical technique. Association between p53 protein overexpression and clinical and pathological parameters as well as prognosis of patients were also analyzed. p53 protein overexpression was commonly observed (69.4%) in OSCC and may be used as a marker of carcinogenesis of OSCC. The level of p53 protein overexpression is correlated with the lower three and five-year survival rate of OSCC. The presence or absence of p53 overexpression was not correlated with sex, age, site of tumor, size of tumor, degree of differentiation, node status, and clinical stage in OSCC. Single factor COX proportional hazards regression model analysis indicated that there was no significant association between p53 overexpression and prognosis of OSCC. Multivariable COX model analysis failed to establish effective life function or risk rate function. These showed that all the parameters analyzed in this study as well as p53 overexpression were not significant and effective risk factors of prognosis for patients with OSCC.

Carcinoma, Squamous Cell↗
PubMedDate not supplied

Impaired motor learning and diffuse axonal damage in motor and visual systems of the rat following traumatic brain injury.

Cognitive-motor functioning or motor skill learning is impaired in humans following traumatic brain injury. A more complete understanding of the mechanisms involved in disorders of motor skill learning is essential for any effective rehabilitation. The specific goals of this study were to examine motor learning disorders, and their relationship to pathological changes in adult rats with mild to moderate closed head injury. Motor learning deficits were determined by comparing the ability to complete a series of complex motor learning tasks with simple motor activity. The extent of neuronal damage was determined using silver impregnation. At all post-injury time points (day 1 to day 14), statistically significant deficits were observed in parallel bar traversing, foot placing, ladder climbing, and rope climbing. Performance improved with time, but never reached control levels. In contrast, no deficits were found in simple motor activity skills tested with beam balance and runway traverse. Histologically, axonal degeneration was widely distributed in several brain areas that relate to motor learning, including the white matter of sensorimotor cortex, corpus callosum, striatum, thalamus and cerebellum. Additionally, severely damaged axons were observed in the primary visual pathway, including the optic chiasm, optic tract, lateral geniculate nuclei, and superior colliculus. These findings suggest that motor learning deficits could be detected in mild or moderate brain injury, and this deficit could be attributed to a diffuse axonal injury distributed both in the motor and the visual systems.

Animals↗