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Biomedical subjects

X C Liu

Publications and source records attributed to X C Liu.

At least 19 recordsLinked to original sources
PubMed2001

Biocatalysis of isomerization of 1,2-benzisoxazole by bovine serum albumin in an organic solvent.

The catalytic properties of bovine serum albumin (BSA) have been studied rather extensively. The protein has shown catalytic activities toward a variety of reactions in aqueous media. However, there appears to be no reports of reactions catalyzed exclusively in organic media. In this study, we report the catalytic property of BSA on the isomerization of 1,2-benzisoxazole in an organic solvent. Kinetics were performed using a continuous flow system in a spectrophotometer at 330 nm. The catalysis showed a Michaelis-Menten behavior with an estimated catalytic efficiency (k(cat)/K(M)) of 8.77 M(-1)S(-1). The influence of water content and inhibitors was also studied. The activity of BSA in acetonitrile is approximately 20% of that in water under similar conditions. Inhibition studies show that the active site may be the pyridoxal binding site involving Lys-220.

Acetonitriles↗
PubMed2001

Functional classification of patients with idiopathic scoliosis assessed by the Quantec system: a discriminant functional analysis to determine patient curve magnitude.

STUDY DESIGN: A stepwise discriminant analysis was used to define a spinal deformity score based on three-dimensional measurements by the Quantec spinal image system (raster stereophotograph). OBJECTIVE: To provide functional classification of spinal deformity in patients with mild idiopathic scoliosis without using radiographs. SUMMARY OF BACKGROUND DATA: Most studies classify the degree of spinal deformity in terms of coronal plane radiograph without analyzing transverse rotation. To the authors' knowledge, no studies investigating classification of spinal deformity in idiopathic scoliosis using Quantec system measurements have been documented. METHODS: In this study, 129 patients with a single curve and 119 patients with a double curve were divided into three groups according to Cobb angle: Group 1 (less than 10 degrees ), Group 2 (10-20 degrees ), and Group 3 (greater than 20 degrees ). RESULTS: The patients were assigned to the group with the highest scores after application of a stepwise discriminant analysis. The accuracy of the classification system by functional scores for the patients with a single curve was 85% for Group 1, 63.5% for Group 2, and 71.7% for Group 3. The accuracy of classification by functional scores for the patients with a double curve was 87.1% for Group 2 and 76.1% for Group 3. CONCLUSION: The back surface image study is a method for providing a quantitative assessment of mild spinal deformity, allowing evaluation of patients by integrated three-dimensional parameters with no reference to radiographs.

Adolescent↗
PubMed2001

Direct measurement of nitric oxide release from saphenous vein: abolishment by surgical preparation.

BACKGROUND: Surgical preparation (distension) of the saphenous vein (SV) is applied routinely during harvesting in coronary artery bypass grafting (CABG). However, mechanical distension may impair the endothelium, which plays an important role in long-term patency. The present study investigated the effect of surgical preparation of the SV on nitric oxide (NO) release from the endothelium by direct measurement of NO. METHODS: Saphenous vein segments taken from CABG patients were cut open longitudinally and placed in an organ chamber. An NO-sensitive electrode and NO meter were used to directly measure NO release induced by acetylcholine (ACh) and bradykinin (BK) from the surgically prepared veins (PV) compared with the control (nondistended) veins. RESULTS: The basal release of NO in the PV group was significantly lower than that in the control group (3.4 +/- 1.4 nM, n = 9 versus 9.9 +/- 2.8 nM, n = 13, p = 0.002). The maximum concentrations of NO release induced by ACh and BK in the PV group were also significantly lower than those in the control veins (for ACh 10(-6) mol/L: 9.6 +/- 3.1 nM, n = 8 versus 41.9 +/- 11.2 nM, n = 12, p = 0.005; for BK 10(-8) mol/L: 8.3 +/- 3.7 nM, n = 7 versus 37.9 +/- 6.1 nM, n = 9, p = 0.003). Further, the duration of NO release in the PV group was significantly shorter than that in control veins (1.5 +/- 1.3 minutes, n = 8 versus 8.1 +/- 1.9 minutes, n = 8, p < 0.001). CONCLUSIONS: Surgical preparation almost abolishes NO release by the SV and this may significantly contribute to the low long-term patency rate of the vein graft.

Endothelium, Vascular↗
PubMed2001

[Association of parameters of crossbreeding effect for traits of growth and meat-production with average band-sharing of RAPD markers in commercial crosses of Duroc, Landrace and large white pigs].

Parameters of crossbreeding effect have been estimated for average daily gain (ADG), dressing percentage (DRP), backfat thickness (BFT), percent of hind legs (HLP), and average band-sharing of RAPD markers, by using individual records of growth and meatproduction and genotypes of RAPD analysis in crosses of Duroc, Landrace and Large White pigs from 1996 through 1998. The results indicate that significant individual and maternal genetic effects exist for all the 4 traits of growth and meat-production (P < 0.05). Effects of individual heterosis and maternal heterosis have also been found to be significant for ADG (P < 0.05), but not significant for DRP, BFT, and HLP (P > 0.05). Maternal genetic effect is positive and the effects of individual heterosis and maternal heterosis are negative for RAPD-marker ABS. Correlation analysis reveals that the total correlation, which includes all parameters at a time, is low and not significant. The partial correlation, however, is more reasonable than total correlation, which consider 1 parameter each time, or 2 in case of heterosis. All 3 partial correlations between ADG and RAPD-marker ABS are significantly greater or smaller than zero (P < 0.05), among which the correlation for individual genetic effect is very significant (P < 0.01). It is therefore concluded that the efficiency of predicting heterosis is low by simply applying total correlation. Alternatively, estimation of parameters of crossbreeding effect for both economic traits and DNA markers provides a way of efficiently predicting heterosis for it dramatically increases the correlation between markers and traits of economical importance. Increasing QTL coverage (percent of markers linked to QTL) will as well contribute to improved accuracy of predicting heterosis. It is also implied from the partial correlations that, while genomic similarity of crosses increases, individual genetic effect would increase, but that of individual heterosis and maternal heterosis would decreases.

Animals↗
PubMed2000

Chemoenzymatic construction of a four-component Ugi combinatorial library.

The chemoenzymatic preparation of a nine-member Ugi condensation library is described. The carboxylic acid and amine precursors are based on 3-hydroxybutyrate and 4-amino-1-butanol, respectively, and have been acylated selectively using a variety of acyl donors catalyzed by porcine pancreatic lipase. The enzyme is selective for the hydroxyl functionalities on both precursors, thereby yielding 3-acyl-butyric acid and 4-amino-1-acyl compounds. These enzymatically generated derivatives were then subjected to a four-component Ugi condensation reaction in the presence of acetaldehyde and methyl isocyanoacetate. Isolated yields of the alpha-(acylamino)amide Ugi products ranged from 72-95%. The inherent chemoselectivity of enzymatic catalysis may play an increasingly important role in expanding the structural diversity that can be achieved by chemical multicomponent condensation reactions.

3-Hydroxybutyric Acid↗
PubMed2000

Three-dimensional rotations of the thoracic spine after distraction with and without rib resection: a kinematic evaluation of the apical vertebra in rabbits with induced scoliosis.

An experimental model of induced scoliosis in New Zealand rabbits was studied to evaluate the effects of rib resection on the apical vertebra during distraction for scoliosis surgery. After concave distraction, three-dimensional rotations of the apical vertebra were measured using a motion analysis system, which included three cameras and six reflective markers. Distraction with rib resection on the convexity produced minimal rotations in the coronal plane (0.77 degrees), sagittal plane (0.96 degrees), and transverse plane (0.61 degrees) compared with no rib resection. The distraction maneuver with rib resection has no significant effect on derotation of the apical vertebra in the coronal and transverse plane, but slightly greater forward rotation was apparent in the sagittal plane (p < 0.05). Resection of three convex ribs directly corrects the rib prominence and does not seem to improve derotation.

Animals↗
PubMed2000

[Genetic epidemiologic study of mitochondrial DNA 7445A-->G mutation among non-syndromic deafness in Chinese population].

OBJECTIVE: To study the Mitochondrial DNA 7445A-->G mutation in nonsyndromic deafness patients in Chinese population. METHOD: Polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) were used to screen the mitochondrial DNA 7445A-->G mutation among 128 nonsyndromic deafness individuals from 32 pedigrees, 135 sporadic nonsyndromic deafness patients and 100 normal subjects. RESULT: The 7445A-->G mutation did not appear in the experiment. CONCLUSION: Incidence of the mitochondrial 7445A-->G mutation was lower than that of mtDNA 1555A-->G mutation in nonsyndromic deafness patients in China.

China↗
PubMed1999

Self-reported depressive symptoms among Chinese adolescents.

Previous reports on the prevalence and features of depression among adolescents have been inconsistent. The purpose of the current study was to estimate the prevalence of depression among Chinese adolescents with a standardized instrument. A total of 2462 students, aged 13-22, were sampled from the Shandong province of China. The Zung Self-Rating Depression Scale (SDS) was administered to the subjects in their classrooms. It was shown that the mean SDS score was 44.8 (SD 9.9) and it decreased significantly from the age of 18 upward (F = 31.73, df = 9, P < 0.01). No significant difference was found between males and females (t = 0.70, P > 0.05). Taking 55 as a cut-off score, the prevalence rate of depression was 16.9% (95% CI = 15.4-18.4%). Logistic regression showed that increasing age appeared to decrease the risk for depression. Most of the individual items differed between ages, except for weight loss and constipation. Principal components factor analysis revealed that the characteristics of adolescent depression were depressive/anxious mood, psychomotor retardation, loss of self-esteem, somatic symptoms and decreased appetite and libido. Although the study was based on a large sample using an established instrument, the sample was not from a general adolescent population and case ascertainment was not by clinical diagnosis.

Adolescent↗
PubMed1999

Doxorubicin overproduction in Streptomyces peucetius: cloning and characterization of the dnrU ketoreductase and dnrV genes and the doxA cytochrome P-450 hydroxylase gene.

Doxorubicin-overproducing strains of Streptomyces peucetius ATCC 29050 can be obtained through manipulation of the genes in the region of the doxorubicin (DXR) gene cluster that contains dpsH, the dpsG polyketide synthase gene, the putative dnrU ketoreductase gene, dnrV, and the doxA cytochrome P-450 gene. These five genes were characterized by sequence analysis, and the effects of replacing dnrU, dnrV, doxA, or dpsH with mutant alleles and of doxA overexpression on the production of the principal anthracycline metabolites of S. peucetius were studied. The exact roles of dpsH and dnrV could not be established, although dnrV is implicated in the enzymatic reactions catalyzed by DoxA, but dnrU appears to encode a ketoreductase specific for the C-13 carbonyl of daunorubicin (DNR) and DXR or their biosynthetic precursors. The highest DXR titers were obtained in a dnrX dnrU (N. Lomovskaya, Y. Doi-Katayama, S. Filippini, C. Nastro, L. Fonstein, M. Gallo, A. L. Colombo, and C. R. Hutchinson, J. Bacteriol. 180:2379-2386, 1998) double mutant and a dnrX dnrU dnrH (C. Scotti and C. R. Hutchinson, J. Bacteriol. 178:7316-7321, 1996) triple mutant. Overexpression of doxA in a doxA::aphII mutant resulted in the accumulation of DXR precursors instead of in a notable increase in DXR production. In contrast, overexpression of dnrV and doxA jointly in the dnrX dnrU double mutant or the dnrX dnrU dnrH triple mutant increased the DXR titer 36 to 86%.

Acyl Carrier Protein↗
PubMed1999

[A preliminary study of developmental genetics of polymorphic serum esterase in domestic fowls].

Polymorphism of serum esterase was examined in 3 Super-Y 2000 broiler breeding populations differing in developmental stages (i.e. day 120, 180 and 300) using vertical polyacrylamide gel electrophoresis. The results indicated that both Es-1 and Es-2 loci exhibited polymorphism. Two to three polymorphic enzyme bands were detected at zone Es-1, and one band at zone Es-2 after electrophoresis. It was first discovered in this work that obvious developmental difference in products of Es-1 alleles existed with female birds, polymorphic bands of which disappeared after onset of lay. An individual tracing experiment conducted in a Super-Y 380 commercial layer population and an extensive experiment carried out in 2 ISA B380 parent CD stocks supported the previous finding. It could thus be inferred that phenotype "O" (no band at Es-1) discovered in hens was not genetically controlled by the recessive allele Es-1(0), which itself did not exist, but might be an evidence of gene regulation at laying period. For female birds, expression of Es-1 alleles was active before sexual maturity, and depressed after onset of lay, to meet their physiological need of high level of blood esterase for laying. It could also be inferred that this developmental difference in serum esterase polymorphism might be a common phenomenon in all avian species. If this hypothesis were true, the synthesis of esterase inside avian bodies could be a desirable model for investigating expression, and regulation of expression, of genes in avian populations.

Animals↗
PubMed1999

Gait pattern in patients with spastic diplegic cerebral palsy who underwent staged operations.

Fifteen patients with spastic diplegic cerebral palsy (CP) were monitored for a mean length of 9.5 years after they underwent staged operations and were evaluated by gait analysis, including joint motion in the sagittal plane and the ground reaction force (GRF) in three dimensions. Results showed an increased hip flexion (132%) at midstance, a reduction of peak knee flexion (PKF) during swing (45%) accompanied by an augmented time of PKF during swing (50%), and an increased dorsiflexion of the ankle during swing (293%) as well as its time during the gait cycle, in comparison with normal values. Moreover, significant decreases of the vertical GRF at the terminal stance and the forward and backward GRF were present. Additionally, it was found that a bilateral popliteal angle < 20 degrees is acceptable in spastic CP. Staged operations gave unpredictable results in the correction of contracture of the hamstrings, the Achilles tendon, and the iliopsoas. The authors are convinced that gait analysis is useful in evaluating these patients and enhances the results of operative treatment, and they have since changed their approach toward multilevel simultaneous corrections.

Adolescent↗
PubMed1997

Life events and anxiety in Chinese medical students.

The authors studied a sample of 537 Chinese medical students aged 15-21 years using Zung's Self-Rating Anxiety Scale (SAS) and a life events checklist. The results showed that test pressure, less free time, peer competition, failure in a test, and financial problems were the most common stressful experiences for medical students during the previous 12 months. Social and personal problems were rated the highest on scores of perceived stress. Of all students, 12.5% scored over the cut-off point on the SAS previously established to indicate risk of psychiatric disorder. Using a stepwise regression analysis, it was shown that poor health status, little physical exercise, financial problems in the family, test pressure, conflict with classmates, the personality trait of introversion, getting up late in the morning, and freshman status were independently associated with the presence of anxiety.

Adolescent↗
PubMed1997

A new technique for the three-dimensional study of the spine in vitro and in vivo by using a motion-analysis system.

We introduce a new method with a motion-analysis system (MAS) to study the vertebral model in vitro. Compared with the currently most accurate technique, roentgen stereophotogrammetric analysis (RSA), the difference between the RSA and the MAS is 0.12 degree +/- 1.64 degrees. An accuracy with an error of 0.08 degree +/- 1.15 degrees is determined by means of an angle gauge. Although a significant difference between the MAS and the goniometer (p = 0.04) is found around the X-axis (theta; transverse plane), it is limited to < 1 degree. The MAS provides an in-depth insight into the mechanism of the three-dimensional rotation at each vertebra in vivo. The backward inclination of the apical vertebra (AV) and forward inclination of the upper-end vertebra (UEV) around the Y-axis (phi) results in a correction of the hypokyphosis shown by the Cobb angle in the sagittal plane. The clockwise rotation of the UEV in the Z-axis (psi) leads to a reduction of the Cobb angle in the frontal plane. Additionally, the MAS as an intraoperative alternative shows different results of the derotation maneuver by the Cotrel-Dubousset instrumentation (CDI) compared with the computed tomography (CT) scan. Our method gives more direct details of the derotation not influenced by patient posture, as observed in the CT scan.

Adolescent↗
PubMed1995

The ground reaction force in the gait of intoeing children.

One hundred twenty-four intoeing and 80 age-matched normal children were studied using the Kistler force plate. Intoeing gait was usually caused by increased femoral anteversion (IFA), internal tibial torsion (ITT), or metatarsus adductus (MAD). Thirty-five children showing spontaneous correction and a return to normal gait (COR) were singled out. Our results confirmed that there were variations of the ground reaction force (GRF) in three directions in the different groups, particularly in the vertical and medial-lateral components. Alterations of magnitude of GRF or duration of stance phase was found to be significant compared with normal subjects. On this basis, we suggest that dynamic forces are related to the remodeling of the epiphyseal plate or respond to actions of the plantar flexors, although we could not discern a specific correlation between them.

Biomechanical Phenomena↗
PubMed1994

Experimental studies on immune-complex in situ type glomerulonephritis in rabbits treated with mai-luo-tong and natural indigo.

By injection of C-BSA, immune-complex in situ type glomerulonephritis was duplicated in rabbits and treated with Mai-Luo-Tong and natural Indigo. The results showed that proteinuria in the treated groups M and Q was decreased. The difference between group M and control group is statistically significant (P < 0.05). Under light and electron microscope, although glomerular basement membrane was irregularly thickened and subepithelial dense electron deposited in the treated group, but microthrombus, erythrocytes and platelets aggregation and leukocytes impaction were not seen within glomerular capillaries. Also in groups C, Q, M, mesenteric cell count was 99.40 +/- 18.53, 92.87 +/- 17.89, 66.55 +/- 7.75 respectively, the M. Q groups are compared with group C, the result is of statistical significance (P < 0.05) and there is no apparent glomerular fibrosis in the treated groups.

Animals↗
PubMed1994

[Injection of 5-fluorouracil in the treatment of tubal pregnancy through salpingo-catheter under hysteroscopy].

Seventeen women with unruptured tubal pregnancy were given 5-FU through salpingo-catheter under hysteroscopy. In one case the injection failed because the tube opening could not be found. The success rate of salpingo-catheterization was 94.12% (16/17). The cure rate for the tubal pregnancies was 88.24% (15/17). 12 cases received injection once and 3 cases twice. The dose of 5-FU per injection was 250 mg in 10 ml solution. Serum beta-hCG test became negative in 7 to 14 days after the treatment, and signs and symptoms disappeared. Salpingography were done in 8 cases after 2 to 3 months, and all the diseased tubes were found patient. There was little side effects due to this treatment, which is more effective, convenient and less traumatic than injecting 5-FU to the affected site through laparoscopy or systemic administration. It may turn out to be an effective, simple, safe and acceptable new method for treating early tubal pregnancy.

Adult↗
PubMed1989

[Influence of electroacupuncture on ACh content and AChE activity in the spinal ganglia of rat].

The spinal ganglion a cell body storage of somatic primary-sensory neurons, is considered as an important region for neurochemical research of primary afferent nerves. The present experiment aims at the observation on the Ach content and its changes in the ganglia of 128 rats by means of biochemical methods under the effect of administration of Neostigmini and application of electroacupuncture. It is found that there are evidence of existence of Ach in the ganglia and when the AchE activity in the periphery nerve system is inhibited, the Ach content of ganglia rose. In addition, during acupuncture (applied at acupoint "Huantiao") analgesia, no apparent changes of Ach content can be visualized in spinal ganglia, however, the level of AchE activity goes up evidently. The foregoing results indicate that in the somatic primary-sensory neuron Ach is one of important neurotransmitters which may influence and take part in the transmission of sensory information through primary afferent nerves.

Acetylcholine↗