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Biomedical subjects

Y Liu

Publications and source records attributed to Y Liu.

At least 271 records · Page 15Linked to original sources
PubMed2002

Transplantation of genetically modified cells contributes to repair and recovery from spinal injury.

The effects of transplantation of fibroblasts genetically modified to produce brain derived neurotrophin factor (Fb/BDNF) on rescue of axotomized neurons, axonal growth and recovery of function was tested in a lateral funiculus lesion model in adult rats. Operated control animals included those in which the lesion was filled with gelfoam implant (Hx) and those in which the cavity was filled with unmodified fibroblasts (Fb). Both Fb/BDNF and Fb transplants survived and filled the lesion site. Unoperated control groups showed a marked retrograde death of Red nucleus neurons contralateral to the lesion; Fb/BDNF recipients showed a significant rescue effect. Anterograde and retrograde labeling studies indicated no regeneration of rubrospinal axons into the lesion/transplant in operated control animals, but regeneration into, around, and through the transplant into the host was seen in the Fb/BDNF recipients. All animals showed deficits on the more challenging behavioral tests but the Fb/BDNF recipients showed fewer deficits, particularly in tests of spontaneous vertical exploration, horizontal rope crossing and a sensory test (patch removal). The improved function on these tests in the Fb/BDNF recipients was abolished by a second lateral funiculus lesion rostral to the transport site. These results indicate that delivery of neurotrophic factors by grafting genetically modified cells can improve repair and function after spinal injury.

Animals↗
PubMed2002

Cleft lip with or without cleft palate and dermatoglyphic asymmetry: evaluation of a Chinese population.

OBJECTIVE: To determine if Chinese individuals with non syndromic cleft lip with or without cleft palate (CL/P) display more dermatoglyphic asymmetry than unaffected relatives or controls. DESIGN: Case-control study with two control groups (genetically related and unrelated). SETTING AND SAMPLE POPULATION: A total of 500 CL/P probands from Shanghai, China, 421 unaffected relatives, and 66 controls of Chinese heritage. METHODS: Finger and palm prints were collected, and pattern frequencies, total ridge counts (TRC), and atd angles were calculated. Asymmetry scores between right and left hands were defined for each of the three dermatoglyphic measures. Probands' asymmetry scores were compared statistically with the scores of unaffected relatives and controls. RESULTS: In general, the probands' asymmetry scores for TRC and atd angle did not differ significantly from the scores of either unaffected relatives or controls. However, probands with a positive family history of clefting showed significantly more asymmetry in their pattern types than either probands without a family history, unaffected relatives or controls. CONCLUSION: These results suggest that a unique genetic mechanism of developmental instability may obtain in CL/P individuals with a positive family history of clefting.

Analysis of Variance↗
PubMed2002

High organic loading influences the physical characteristics of aerobic sludge granules.

AIMS: The effect of high organic loading rate (OLR) on the physical characteristics of aerobic granules was studied. METHODS AND RESULTS: Two column-type sequential aerobic sludge blanket reactors were fed with either glucose or acetate as the main carbon source, and the OLR was gradually raised from 6 to 9, 12 and 15 kg chemical oxygen demand (COD) m(-3) d(-1). Glucose-fed granules could sustain the maximum OLR tested. At a low OLR, these granules exhibited a loose fluffy morphology dominated by filamentous bacteria. At higher OLRs, these granules became irregularly shaped, with folds, crevices and depressions. In contrast, acetate-fed granules had a compact spherical morphology at OLRs of 6 and 9 kg COD m(-3) d(-1), with better settling and strength characteristics than glucose-fed granules at similar OLRs. However, acetate-fed granules could not sustain high OLRs and disintegrated when the OLR reached 9 kg COD m(-3) d(-1). CONCLUSIONS: The compact regular microstructure of the acetate-fed granules appeared to limit mass transfer of nutrients at an OLR of 9 kg COD m(-3) d(-1). The looser filamentous microstructure of the glucose-fed granules and the subsequent irregular morphology delayed the onset of diffusion limitation and allowed significantly higher OLRs to be attained. SIGNIFICNACE AND IMPACT OF THE STUDY: High organic loading rates are possible with aerobic granules. This research would be helpful in the development of aerobic granule-based systems for high-strength wastewaters.

Acetic Acid↗
PubMed2002

Aerobic granules: a novel zinc biosorbent.

AIMS: Aerobic granules are aggregates with a compact and porous microbial structure. In view of the potential use of aerobic granules as biosorbents for Zn(II) removal from industrial wastewater, this study investigated the effects of initial Zn(II) and aerobic granule concentrations on the kinetics of Zn(II) biosorption on the aerobic granule surface. METHODS AND RESULTS: Acetate-fed aerobic granules with a mean diameter of 1.0 mm were used as biosorbents. Results showed that the kinetics of Zn(II) biosorption on the aerobic granule surface were related to both initial Zn(II) and granule concentrations. It was found that the real driving force for Zn(II) biosorption on the aerobic granule surface could be described by the ratio of initial Zn(II) concentration (Co) to initial granule concentration (Xo), rather than individual Co or Xo. The Co/Xo ratio provides a unified basis for interpretation of the biosorption data obtained under different initial conditions. The maximum biosorption capacity of Zn(II) by aerobic granules was 270 mg g(-1). CONCLUSIONS: It appears that the aerobic granule can be used as an effective biosorbent for efficient removal of Zn(II) or other types of heavy metals from industrial wastewater. SIGNIFICANCE AND IMPACT OF THE STUDY: This study could lead to the development of a novel granular biosorbent for the removal of heavy metals from wastewater. A simple and compact aerobic granule-based biosorber could be expected.

Absorption↗
PubMed2002

HSP70 expression in skeletal muscle of patients with peripheral arterial occlusive disease.

OBJECTIVES: heat shock protein (HSP70) has been studied in the ischaemic myocardium and proven to provide protection against ischaemia. However, HSP70 in ischaemic skeletal muscle in patients with peripheral arterial occlusive disease (PAOD) has not been reported. METHODS: thirty-four patients with PAOD (Fontaine's criteria: stage II: 15; III: 9 and IV: 10, respectively) and ten non-PAOD controls were enrolled in the study. Calf muscle samples were taken. HSP70 was quantitated by SDS-PAGE using ultrasensitive silver staining with reference to a series of standard HSP70, and HSP70 mRNA was estimated using RT-PCR. RESULTS: in comparison with the controls [median with range: 24.8 (14.1-35.6) ng in 2.5 microg total protein], HSP70 was increased significantly in PAOD [stage II: 93.1 (62.7-114.3); stage III: 110.1 (89.7-134.5) and stage IV: 77.4 (67.3-101.1)]. Similar results were obtained with HSP70 mRNA. CONCLUSIONS: HSP70 is increased in the ischaemic skeletal muscle in patients with PAOD, and HSP70 expression is different with regard to clinical stages, and the upregulation of HSP70 mRNA implies that the expression of HSP70 seems to be regulated at transcriptional level.

Aged↗
PubMed2002

Training intensity influences leptin and thyroid hormones in highly trained rowers.

Leptin (L) is associated with body-weight-regulating and adipostatic functions. Its receptors also may be found centrally. Thyroid hormones regulate metabolic processes mainly by binding at peripheral receptors. Aim of this study was to show if there is a link between those central and peripheral regulation systems and to investigate the influence of different training intensities on L and the hypothalamic-thyroid-axis (HTA) in highly trained rowers. Six rowers (18.9 +/- 2.6 y; BMI 22.8 +/- 2.1 kg/m (2)) undertook high intensity resistance training (RT) for three weeks followed by three weeks of endurance training (ET). After each training cycle the subjects had one week for recovery (R1, R2). Blood samples were taken before and at the end of RT, R1, ET and R2. L, thyroid stimulating hormone (TSH), free T3 (fT3) and free T4 (fT4) were measured. After RT, a significant reduction in L, TSH and fT3 was found (p < 0.05). fT4 was unchanged. L remained decreased until the end of R1. After ET, a significant increase of TSH was found. L correlated to basal TSH levels (r = 0.49, p = 0.006) during R. BMI and body fat were unchanged throughout the study and were not correlated with hormonal levels. We speculate a high energy flux during intensified training (RT) caused the decrease of L and the HTA, independent of BMI or body fat. Thus, we conclude a depression of L and HTA is associated with training intensity.

Adolescent↗
PubMed2002

Erythropoiesis and performance after two weeks of living high and training low in well trained triathletes.

The purpose of our study was to evaluate hematologic acclimatization during 2 weeks of intensive normoxic training with regeneration at moderate altitude (living high-training low, LHTL) and its effects on sea-level performance in well trained athletes compared to another group of equally trained athletes under control conditions (living low - training low, CONTROL). Twenty-one triathletes were ascribed either to LHTL (n = 11; age: 23.0 +/- 4.3 yrs; VO 2 max: 62.5 +/- 9.7 [ml x min -1 x kg -1]) living at 1956 m of altitude or to CONTROL (n = 10; age: 18.7 +/- 5.6 yrs; VO 2 max: 60.5 +/- 6.7 ml x min -1 x kg -1) living at 800 m. Both groups performed an equal training schedule at 800 m. VO 2 max, endurance performance, erythropoietin in serum, hemoglobin mass (Hb tot, CO-rebreathing method) and hematological quantities were measured. A tendency to improved performance in LHTL after the camp was not significant (p < 0.07). Erythropoietin concentration increased temporarily in LHTL (Delta 14.3 +/- 8.7 mU x ml -1; p < 0.012). Hb tot remained unchanged in LHTL whereas was slightly decreased from 12.5 +/- 1.3 to 11.9 +/- 1.3g x kg -1 in CONTROL (p < 0.01). As the reticulocyte number tended to higher values in LHTL than in CONTROL, it seems that a moderate stimulation of erythropoiesis during regeneration at altitude served as a compensation for an exercise-induced destruction of red cells.

Acclimatization↗
PubMed2002

Characteristics of aerobic granules grown on glucose and acetate in sequential aerobic sludge blanket reactors.

Aerobic granules were cultivated in two column-type sequential aerobic sludge blanket reactors fed with glucose and acetate, respectively. The characteristics of aerobic granules were investigated. Results indicated that the glucose- and acetate-fed granules have comparable characteristics in terms of settling velocity, size, shape, biomass density, hydrophobicity, physical strength, microbial activity and storage stability. Substrate component does not seem to be a key factor on the formation of aerobic granules. However, microbial diversity of the granules is closely associated with the carbon sources supplied to the reactors. Compared with the conventional activated sludge flocs, aerobic granules exhibit excellent physical characteristics that would be essential for industrial application. This research provides a complete set of characteristics data of aerobic granules grown on glucose and acetate, which would be useful for further development of aerobic granules-based compact bioreactor for handling high strength organic wastewater.

Aerobiosis↗
PubMed2002

Genotype associations of factor VII gene with plasma factor VII coagulant activity and antigen levels in healthy Chinese.

A raised plasma factor VII (FVII) level is one of the risk factors for coronary artery disease. The R353Q polymorphism at codon 353 and the 10 base pair (bp) insertion (0/10 bp) polymorphism of the FVII gene have been reported to be associated with plasma FVII levels in several populations. We investigated these two polymorphisms in 209 male and 214 female healthy Chinese. The allele frequencies of 10 bp and Q were 0.036 and 0.045, respectively. Strong linkage disequilibrium was observed between these two sites (Delta = 0.85, P < 0.001). There were significant genotype associations of these two loci with FVII coagulant activity (FVIIc) and antigen (FVIIAg) levels. Heterozygous individuals had lower FVIIc and FVIIAg levels than those homozygous for the common alleles. When analyzed separately by gender, the 0/10 bp polymorphism was strongly associated with FVIIAg levels in males and females. However, both polymorphisms were significantly associated with FVIIc levels only in the females. The effect of 0/10 bp polymorphism predominated over that of the R353Q polymorphism in a two-way analysis of variance procedure. In the Chinese, the 10 bp insertion may reduce transcription of the FVII gene, leading to the decreased synthesis of FVII protein and thus FVIIc.

Adult↗
PubMed2002

Overtime work, insufficient sleep, and risk of non-fatal acute myocardial infarction in Japanese men.

OBJECTIVES: To examine the relation between working hours and hours of sleep and the risk of acute myocardial infarction (AMI), with special reference to the joint effect of these two factors. METHOD: Case-control study in Japan. Cases were 260 men aged 40-79 admitted to hospitals with AMI during 1996-8. Controls were 445 men free from AMI matched for age and residence who were recruited from the resident registers. Odds ratios of AMI relative to mean weekly working hours and daily hours of sleep in the past year or in the recent past were calculated. RESULTS: Weekly working hours were related to progressively increased odds ratios of AMI in the past year as well as in the past month, with a twofold increased risk for overtime work (weekly working hours >or=61) compared with working hours <or=40. Short time sleep (daily hours of sleep <or=5) and frequent lack of sleep (2 or more days/week with <5 hours of sleep) were also associated with a two to threefold increased risk. Frequent lack of sleep and few days off in the recent past showed greater odds ratios than those in the past year. CONCLUSIONS: Overtime work and insufficient sleep may be related to increased risk of AMI.

Adult↗
PubMed2002

Bradykinin does not mediate cutaneous active vasodilation during heat stress in humans.

To test the hypothesis that bradykinin effects cutaneous active vasodilation during hyperthermia, we examined whether the increase in skin blood flow (SkBF) during heat stress was affected by blockade of bradykinin B(2) receptors with the receptor antagonist HOE-140. Two adjacent sites on the forearm were instrumented with intradermal microdialysis probes for local delivery of drugs in eight healthy subjects. HOE-140 was dissolved in Ringer solution (40 microM) and perfused at one site, whereas the second site was perfused with Ringer alone. SkBF was monitored by laser-Doppler flowmetry (LDF) at both sites. Mean arterial pressure (MAP) was monitored from a finger, and cutaneous vascular conductance (CVC) was calculated (CVC = LDF/MAP). Water-perfused suits were used to control body temperature and evoke hyperthermia. After hyperthermia, both microdialysis sites were perfused with 28 mM nitroprusside to effect maximal vasodilation. During hyperthermia, CVC increased at HOE-140 (69 +/- 2% maximal CVC, P < 0.01) and untreated sites (65 +/- 2% maximal CVC, P < 0.01). These responses did not differ between sites (P > 0.05). Because the bradykinin B(2)-receptor antagonist HOE-140 did not alter SkBF responses to heat stress, we conclude that bradykinin does not mediate cutaneous active vasodilation.

Adult↗
PubMed2002

Effect of porcine fetal enamel matrix derivative on chondrocyte proliferation, differentiation, and local factor production is dependent on cell maturation state.

Recent studies have shown that porcine fetal enamel matrix derivative (EMD) can enhance the osteoinductive ability of demineralized freeze-dried bone allograft (DFDBA) in a nude mouse muscle implantation model. This suggests that one or more components of EMD can regulate the process of endochondral ossification initiated by DFDBA. To substantiate this hypothesis, in the current study, chondrocytes in the endochondral pathway at two stages of maturation were tested for their response to EMD. Chondrocytes were isolated from the resting zone and growth zone (prehypertrophic and upper hypertrophic cell zones) of the costochondral growth plate cartilage of adolescent rats. The results showed that the relatively immature resting zone cells responded to EMD with an increase in proliferation and a decrease in differentiation as measured by alkaline-phosphatase-specific activity. In addition, EMD stimulated a fivefold increase in PGE(2) production, but was without effect on collagen synthesis, proteoglycan sulfation, and TGF-beta(1) production. The more mature growth zone cells also responded to EMD with increased proliferation, but alkaline-phosphatase-specific activity was unchanged, and there was only a modest increase in PGE(2) production. In contrast to resting zone cells, growth zone cells exhibited a decrease in collagen synthesis, proteoglycan sulfation, and TGF-beta(1) production. These observations indicate that EMD has prominent effects on cells in the endochondral pathway. In particular, EMD stimulates the production of more cells, but inhibits their maturation. This would increase the pool of cells available for subsequent differentiation in response to other factors.

Alkaline Phosphatase↗
PubMed2002

Aerobic granulation in sequential sludge blanket reactor.

Aerobic granulation was studied in a column-type of sequential sludge blanket reactor. Reactor was operated 4 hours per cycle under a chemical oxygen demand (COD) loading rate of 6.0 kg/m3/d by using acetate as substrate. Results showed that aerobic granules with a mean diameter of 0.35 mm were observed at cycle 42. With granulation proceeding, the sludge volume index (SVI) value gradually decreased, and to an average value of 50 mL/g at stable granulation period. Observation of granules' microstructure by scanning electron microscopy (SEM) showed that rod bacteria were dominant in granules with lots of cavities presented. An increase in cell hydrophobicity was observed after the appearance of aerobic granules. The cell hydrophobicity of sludge was found to be about 50% higher after granulation. It appears that high hydrophobicity could induce cell attachment and further strengthen cell-cell interaction; cell hydrophobicity might therefore play a major role in the formation of aerobic granules.

Bacteria, Aerobic↗
PubMed2002

Developments in reduction and replacement of in vivo toxicity and potency tests for pertussis vaccines.

The regulatory control of pertussis vaccines, as for other biological products, requires that they conform to specified standards of safety and efficacy. The current potency test for whole cell vaccines, the intracerebral mouse protection test (AMPT) is still the only such assay that has shown a correlation with protection in children. An alternative in vivo assay based on non-lethal aerosol challenge of mice has been assessed as a replacement for the current AMPT. An in vitro assay based on determination of reactive nitrogen/oxygen intermediates produced as a result of macrophage activation has also been investigated as a potential replacement for the in vivo challenge test. On the other hand, for safety testing, an enzymatic-HPLC coupled assay using a fluorescein-labelled G alpha(i3)C20 peptide to measure the enzymatic ribosylation activity of active pertussis toxin was evaluated for its suitability as a replacement for the current histamine sensitisation test (HIST). An assay for adenylate cyclase toxin (ACT)-related toxicity, based on measuring the ACT-induced oxidative burst in macrophage-like cell cultures has also been investigated. Although some questions still need to be answered in relation to the development of suitable replacements for in vivo tests of pertussis vaccines, the prospects for further improvements are promising.

Animal Testing Alternatives↗
PubMed2001

Construction of a square-planar molecular box: self-assembly of palladium(II) complexes of 3,6,9,16,19,22-hexaazatricyclo[22.2.2.2(11,14)]triacon-11,13,24,26(1),27,29-hexaene through hydrogen-bonding interactions.

Binuclear palladium(II) complexes of the macrocyclic polyamine 3,6,9,16,19,22-hexaazatricyclo[22.2.2.2(11,14)]triacon-11,13,24,26(1),2 7,29-hexaene (L) are used to construct molecules having special shapes. In this study two binuclear palladium(II) complexes [Pd(2)LI(2)]I(2)and [Pd(2)LCl(2)](NO(3))(2).H(2)O are synthesized and structurally characterized. X-ray crystallography shows that both complexes exist as one-dimensional chains formed via intermolecular hydrogen-bonding N(3)-H(3C)---X in which X is I and Cl. Moreover, the ligands in both complexes adopt a boatlike conformation that may facilitate the formation of the tetranuclear complex. The cationic aqua complex [Pd(2)L(H(2)O)(m)(NO(3))(n)]((4-n)+, obtained by the treatment of [Pd(2)LI(2)]I(2)and [Pd(2)LCl(2)]Cl(2) with AgNO(3), is used as a building block for the construction of a tetranuclear palladium(II) complex [Pd(4)L(2)(C(2)O(4))(2)](NO(3))(4).6H(2)O. X-ray crystallography shows that the tetranuclear complex forms an open, hydrophobic box. These molecular boxes are connected via the hydrogen bond N(3)-H(3C)---O(4B) (symmetry code B: x, 1 + y, z) into a one-dimensional chain. A two-dimensional structure is formed via pi-pi stacking of the plane defined by C6 to C11 in the one chain and its symmetry-related plane (symmetry code C: -x, -1 - y, 2 - z) in another chain. This study exemplifies a new method for the assembly of molecular boxes using a macrocyclic ligand.

Journal Article↗
PubMed2001

Crystallization and preliminary X-ray crystallographic studies of a macromolecular antitumour antibiotic, C1027.

C1027 is a macromolecular antitumour antibiotic produced by Streptomyces globispourus C1027 and consists of an apoprotein and a non-protein labile chromophore. Little is known about how the thermally unstable chromophore is stabilized by the apoprotein. The purified C1027 was monodisperse according to dynamic light-scattering measurements and crystallized in two different crystal forms from two different starting conditions using the vapour-diffusion method. Condition I yielded hexagonal prism crystals having space group P3(1)/P3(2) and unit-cell parameters a = b = 66.8, c = 55.4 A. Diffraction data were collected to 2.1 A resolution using an in-house Rigaku rotating Cu anode X-ray generator. Another condition produced rod-like crystals with space group P3(1)21/P3(2)21 and unit-cell parameters a = b = 55.15, c = 55.87 A. A data set to 1.8 A resolution was collected from a rod-like crystal using a MAR CCD detector at the SRS synchrotron source.

Aminoglycosides↗
PubMed2001

Strain differences in the toxicity of cadmium to trigeminal ganglia in mice.

Cadmium (Cd) is toxic to sensory ganglia in many animal species. Cadmium uptake is low in the central nervous system, but it distributes preferentially to peripheral sensory and autonomic ganglia. Strain differences have been demonstrated in the sensitivity of mice to Cd-induced hepatotoxicity, testicular toxicity, and teratogenicity. To study the sensitivity of different mouse strains to Cd toxicity in sensory ganglia, eight strains of mice (four sensitive to testicular toxicity: 129/SVIM, AKR/J, DBA/1J, and C57BR/J; and four resistant: Balb/C, C3H/HeJ, A/J, and C57BL/6J) were given 15 micromol CdCl(2)/kg iv. Trigeminal ganglia (TG) were harvested 24 h later and examined by light microscopy for pathologic lesions. Cadmium induced degeneration of ganglion cells in five strains, namely 129/SVIM, AKR/J, DBA/1J, C57BR/J, and C3H/HeJ mice. These are the same strains that show sensitivity to testicular toxicity, except for C3H/HeJ, which is resistant to testicular toxicity. Cd also induced focal hemorrhages around the ganglion cells and nerve fibers in two of these strains (129/SVIM and AKR/J) and scattered foci of necrosis in C3H/HeJ and 129/SVIM strains. There was no morphologic abnormality in three strains, namely Balb/C, A/J, and C57BL/6J. To examine the mechanism of these strain differences in toxicity, all eight strains of mice were given a nontoxic dose of Cd (0.4 micromol CdCl(2)/kg, 20 microCi (109)Cd/kg iv). Cadmium distribution to the brain and trigeminal ganglia was determined 30 min later by gamma scintillation spectrometry. Cadmium content in the brain was very low and did not differ among the eight strains. In contrast, Cd content was higher in trigeminal ganglia of four of the five strains showing trigeminal ganglia sensitivity than in the three strains showing resistance. In conclusion, the toxicity of Cd to trigeminal ganglia is different among various strains of mice. This strain difference in toxicity appears to be due, at least in part, to differences in the distribution of Cd to the ganglia, but it is clearly not the only factor.

Animals↗