Growth regulatory factors and bone.
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Animals↗
Biomedical subjects
C Xu
Publications and source records attributed to C Xu.
Apparent fat digestibility in rats fed different diets is negatively correlated with faecal bile acid excretion.
Seventy-two rats were fed one out of 9 diets differing as to protein source and calcium concentration. For the individual rats apparent fat digestibility and faecal bile acid excretion were negatively correlated. It is suggested that a high solubility of bile acids in the small intestinal digesta, which is associated with little loss of bile acids with faeces, stimulates the process of fat digestion.
Animals↗
Feeder-free growth of undifferentiated human embryonic stem cells.
Previous studies have shown that maintenance of undifferentiated human embryonic stem (hES) cells requires culture on mouse embryonic fibroblast (MEF) feeders. Here we demonstrate a successful feeder-free hES culture system in which undifferentiated cells can be maintained for at least 130 population doublings. In this system, hES cells are cultured on Matrigel or laminin in medium conditioned by MEF. The hES cells maintained on feeders or off feeders express integrin alpha6 and beta1, which may form a laminin-specific receptor. The hES cell populations in feeder-free conditions maintained a normal karyotype, stable proliferation rate, and high telomerase activity. Similar to cells cultured on feeders, hES cells maintained under feeder-free conditions expressed OCT-4, hTERT, alkaline phosphatase, and surface markers including SSEA-4, Tra 1-60, and Tra 1-81. In addition, hES cells maintained without direct feeder contact formed teratomas in SCID/beige mice and differentiated in vitro into cells from all three germ layers. Thus, the cells retain fundamental characteristics of hES cells in this culture system and are suitable for scaleup production.
Cell Culture Techniques↗
Linkage analysis in multiple sclerosis of chromosomal regions syntenic to experimental autoimmune disease loci.
Multiple sclerosis is a demyelinating disorder of the central nervous system with a putative autoimmune aetiology in which several genes are thought to be involved. Four published genomic screens have confirmed that a gene influencing MS resides within or close to the HLA class II region in 6p21. Still, this locus is likely to confer only a part of the genetic susceptibility in MS. Further, all four studies identified a number of other regions with possible linkage. We have investigated eight chromosomal intervals syntenic to loci of importance for experimental autoimmune model diseases in the rat in 74 Swedish MS families. Possible linkage (a non-parametric linkage NPL score of 1.16 by GENEHUNTER computer package) was observed with markers in 12p13.3, a region syntenic to the rat Oia2 locus which is importance for oil induced arthritis (OIA). Four markers in the T cell receptor beta chain gene region in 7q35 showed possible linkage (highest NPL score of 1.16). This locus is syntenic to the rat Cia3 locus (collagen induced arthritis). These two loci at least partially overlap with chromosomal regions showing indicative evidence for linkage in the previous MS genomic screens. Indeed, both Oia2 and Cia3 were recently found to be linked also with experimental autoimmune encephalomyelitis, a commonly used model for MS. Markers in 2p12, 3p25, 10q11.23, 17q21-25, 19q13.1, and 22q12-13 failed to provide evidence for linkage. We conclude that evidence is amounting that 12p13-12 and 7q34-36 may harbour genes with an importance for MS. The synteny with experimental loci may eventually facilitate their identification.
Alleles↗
Linkage analysis suggests a region of importance for multiple sclerosis in 3p14-13.
Four genomic screens for linkage in multiple sclerosis (MS) have been reported. They confirmed the established role of the human leucocyte antigen (HLA) complex genes in MS and, in addition, suggested the importance of a few other chromosomal segments. Here we report evidence for the importance of 3p14-13 region identified by suggestive linkage in genomic screens from Canada and the United Kingdom. When studying 146 Nordic MS multiplex families, mostly affected sib-pairs, with eight microsatellite markers, spanning a 36-cM region, we observed a two-point non-parametric linkage (NPL) score of 2.39 (P = 0.007) by the GENEHUNTER package for marker D3S1285 and a multipoint NPL score of 1.20 in the same region. Association studies in Swedish MS patients revealed modest allelic associations of uncertain significance not supported by transmission analysis. Analysis of the trinucleotide repeat sequence of the SCA7 gene in Swedish index cases did not reveal expansions. We conclude that support was obtained for the location of a gene or genes with importance for MS susceptibility in 3p14-13 region.
Alleles↗
Electrochemical detection of sequence-specific DNA using a DNA probe labeled with aminoferrocene and chitosan modified electrode immobilized with ssDNA.
The electrochemical detection of sequence-specific DNA using a DNA probe labeled with aminoferrocene (AFC) is reported. Sample ssDNA was immobilized on a chitosan modified glassy carbon electrode. A sequence-known DNA with 256 bp [obtained by polymerase chain reaction (PCR)] was successfully labeled with the electro-active reagent AFC by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide for the first time. This DNA probe labeled with AFC was applied to hybridize with a sequence-unknown DNA sample. Only the complementary sequence (cDNA) could form a double-stranded DNA (dsDNA) with the DNA probe labeled with AFC. The anodic peak currents (ipa) of the AFC bound to the dsDNA by differential pulse voltammetry were used for the determination of cDNA. The ipa of AFC was linearly related to the concentration of cDNA sequence between 1.0 x 10(-8) and 6.0 x 10(-6) mol L-1. The detection limit was 2.0 x 10(-9) mol L-1 using 3 sigma (where sigma is the standard deviation of blank solution, n = 11). The probe showed high sensitivity and selectivity.
Animals↗
C1q-bearing immune complexes induce IL-8 secretion in human umbilical vein endothelial cells (HUVEC) through protein tyrosine kinase- and mitogen-activated protein kinase-dependent mechanisms: evidence that the 126 kD phagocytic C1q receptor mediates immune complex activation of HUVEC.
Endothelial cells play a pivotal role in the initiation and perpetuation of inflammation. C1q, the first component of the classical pathway of complement, is a potent stimulus leading to endothelial cell activation and cytokine production. The specific cellular mechanisms through which endothelial cells are stimulated by C1q are not known. We stimulated human umbilical vein endothelial cells (HUVEC) with either monomeric C1q or C1q-bearing immune complexes (C1q-IC) in the presence or absence of inhibitors of protein tyrosine kinases (PTK) or mitogen-activated protein kinases (MAPK). C1q-IC, but not monomeric C1q, induced IL-8 production in dose- and time-dependent fashion. R3, a cross-linking monoclonal IgM antibody against the 126 kD phagocytic C1q receptor (C1qR), also stimulated IL-8 production. IL-8 mRNA accumulation was detected by Northern blot analysis within 2 h of stimulation by the immune complexes and was enhanced by the addition of cycloheximide. Secretion of IL-8 by C1q-IC stimulated HUVEC was completely blocked by the PTK inhibitor, genistein or the MAPK inhibitor, UO126. These experiments demonstrate that C1q-IC-induced production of IL-8 in HUVEC is dependent upon the activation of PTK and MAPK. These findings also support a role for the phagocytic C1qR as an important activator of HUVEC by immune complexes.
Antigen-Antibody Complex↗
Determination of peripheral blood stem cells by the Sysmex SE-9500.
The Sysmex SE-9500 automated haematology analyser provides an estimate of immature cells, referred to as 'haematopoietic progenitor cells' (HPC). The aim of this study was to evaluate the reliability and usefulness of the SE-9500 HPC parameter as compared with the CD34 + cell count and to determine whether the HPC count was of value in predicting the optimal harvesting time for peripheral blood stem cells (PBSC). Studies were performed on 112 samples from 21 patients with haematological malignancies and 13 healthy donors undergoing progenitor cell mobilisation. Coefficients of variation for the HPC count were 30%, 23.8%, 12.4% and 8.3% respectively for samples with low (4 x 106/l), medium (13 x 106/l), high (250 x 106/l) and very high (2413 x 106/l) counts. There was good linearity for HPC measurement in both peripheral blood (PB) and purified CD34 + cell suspensions (r > 0.995), and no detectable carryover was observed. There was an acceptable correlation between HPC and CD34 + cell counts for PB samples (r=0.669) and for CD34 + cell suspensions (r=0.859). Analysis of purified CD34 + cells using the SE-9500 HPC mode revealed that they appear both in the blast cell area and the immature granulocyte area of the analyser cell display. Quantitation of CD34 + cells and HPC during PBSC mobilisation showed good agreement between these parameters with regard to the optimal time for PBSC harvesting. These findings suggest that HPC counting with the Sysmex SE-9500 may be clinically useful for optimising the timing of PBSC collection.
Antigens, CD34↗
Pressure-exploration of the 33-kDa protein from the spinach photosystem II particle.
The 33-kDa protein isolated from the spinach photosystem II particle is an ideal model to explore high-pressure protein-unfolding. The protein has a very low free energy as previously reported by chemical unfolding studies, suggesting that it must be easy to modulate its unfolding transition by rather mild pressure. Moreover, the protein molecule consists of only one tryptophan residue (Trp241) and eight tyrosine residues, which can be conveniently used to probe the protein conformation and structural changes under pressure using either fluorescence spectroscopy or fourth derivative UV absorbance spectroscopy. The different experimental methods used in the present study indicate that at 20 degrees C and pH 6, the 33-kDa protein shows a reversible two-state unfolding transition from atmospheric pressure to about 180 MPa. This value is much lower than those found for the unfolding of most proteins studied so far. The unfolding transition induces a large red shift of the maximum fluorescence emission of 34 nm (from 316 nm to 350 nm). The change in standard free energy (DeltaGo) and in volume (DeltaV) for the transition at pH 6.0 and 20 degrees C are -14.6 kJ.mol-1 and -120 mL.mol-1, respectively, in which the DeltaGo value is consistent with that obtained by chemical denaturation. We found that pressure-induced protein unfolding is promoted by elevated temperatures, which seem largely attributed to the decrease in the absolute value of DeltaGo (only a minor variation was observed for the DeltaV value). However, the promotion of the unfolding by alkaline pH seems mainly related to the increase in DeltaV without any significant changes in DeltaGo. It was also found that NaCl significantly protects the protein from pressure-induced unfolding. In the presence of 1 M NaCl, the pressure needed to induce the half-unfold of the protein is shifted to a higher value (shift of 75 MPa) in comparison with that observed without NaCl. Interestingly, in the presence of NaCl, the value of DeltaV is significantly reduced whilst that of DeltaGo remains as before. The unfolding-refolding kinetics of the protein has also been studied by pressure-jump, in which it was revealed that both reactions are a two-state transition process with a relatively slow relaxation time of about 102 s.
Anilino Naphthalenesulfonates↗
Aneurysmal and occlusive atherosclerosis of the human abdominal aorta.
PURPOSE: The purpose of this study was to assess atherosclerotic plaque deposition and aortic wall responses in the abdominal aorta in relation to the development of aneurysmal and occlusive disease in the infrarenal aorta. METHODS: Morphologic differences at five standardized locations in the infrarenal aorta in 67 pressure perfusion-fixed male cadaver aortas (aged, 41-98 years; mean, 66 years) were studied and compared with the supraceliac segment. Quantitative computer-assisted morphometry of histologic sections included measurement of plaque area, lumen area, lumen diameter, media thickness, number of medial elastic lamellae, and the area encompassed by the internal elastic lamina that best represents the artery size of each segment. The ratio of the supraceliac segment to the midabdominal segment (normally greater than 1.3) was used to define three groups: Group I (normal): ratio greater than or equal to 1.30 (n = 31); Group II (intermediate): ratio greater than or equal to 1.20 but less than 1.30 (n = 20); and Group III: ratio less than 1.20 (n = 16), which represented dilated midabdominal aortas. There was no significant difference in age among the groups. RESULTS: Group I had minimal intimal plaque and little gross evidence of atherosclerosis. Group II had increased intimal plaque compared with Group I (P <.01) and gross evidence of atherosclerosis, which was maximally localized in the distal aorta; there was no aortic enlargement or thinning of the media underneath the plaque. Group III had more intimal plaque than Group I (P <.01) and Group II (P <.01) and was associated with localized aortic enlargement and media thinning compared with Group I (P <.05) and Group II (P <.01). Increasing intimal plaque in Group III correlated with an increase in lumen diameter (r = 0.61, P <.05), but this relationship was not significant in Group I and Group II. The aortic media in Group III had a reduced number of medial elastic lamellae, was reduced in thickness, and was more exposed to increased wall stress than the aortas in Groups I and II. CONCLUSION: These results suggest that there may be different local responses to atherosclerosis in the abdominal aorta in human beings. Plaque deposition associated with localized dilation, thinning of the media, and loss of medial elastic lamellae may predispose that segment of aorta to subsequent aneurysm formation. Plaque deposits without media thinning, without loss of elastic lamellae, and without artery wall dilation may predispose the aorta, in the event of continuing plaque accumulation, to the development of lumen stenosis.
Adult↗
Molecular mechanisms of aortic wall remodeling in response to hypertension.
OBJECTIVE: The molecular basis of vascular response to hypertension is largely unknown. Both cellular and extracellular components are critical. In the current study we tested the hypothesis that there is a balance between vascular cell proliferation and cell death during vessel remodeling in response to hypertension. METHODS: A midthoracic aortic coarctation was created in rats to induce an elevation of blood pressure proximal to the coarctation. The time course was 1 and 3 days and 1, 2, and 4 weeks for the study of the proximal aorta. Ribonuclease protection assay and Western blot analysis were used to evaluate gene expression of growth and apoptosis-related cytokines with two sets of multiple probes, rCK-3 and rAPO-1. Cell proliferation was determined with BrdU (5-bromo-2'-deoxyuridine) incorporation. Apoptosis was examined with TUNEL (transferase-mediated dUTP nick end-labeling). Morphometry was performed on histologic sections. RESULTS: Coarctation produced hypertension in the proximal aorta, 118 +/- 9 mm Hg versus 94 +/- 6 mm Hg in controls (P <.002). Both messenger RNA and protein levels of transforming growth factor (TGF)-beta1 and TGF-beta3 were increased (P <.005 vs controls). Messenger RNA and protein of Bcl-xS and Fas ligand, known as proapoptotic factors, were both reduced after coarctation (P <.005 vs controls). There was increased BrdU incorporation at 3 days and 1 and 2 weeks (P <.001 vs controls). There were no remarkable changes in the apoptosis rate until 4 weeks later. CONCLUSION: Cell proliferation was stimulated at 3 days, and apoptosis was halted until 4 weeks. These changes were associated with upregulation of TGF-beta and downregulation of Bcl-xS and Fas ligand gene expression. These findings suggest that a coordinated regulation of cell proliferation and cell death contributes to arterial remodeling in response to acute sustained elevation of blood pressure. Cell proliferation precedes apoptosis by 2 weeks in this procedure.
Animals↗
Pneumatic lithotripsy versus laser lithotripsy in the endoscopic treatment of ureteral calculi.
PURPOSE: To compare the efficacy, safety, and features of pneumatic lithotripsy (PL) with those of laser lithotripsy (LL) and present our clinical experience in the endoscopic management of ureteral calculi. PATIENTS AND METHODS: From August 1994 to February 2000, 285 consecutive patients underwent endoscopic lithotripsy with either the Swiss Lithoclast pneumatic lithotripter (145 patients) or the Ho:YAG laser lithotripter (140 patients) for the treatment of ureteral calculi. RESULTS: In one single session, the overall successful stone fragmentation rate of LL was higher than that of PL (95.7% v 69.7%; P < 0.01). The average time to stone-free status was shorter for LL than for PL (18 days v 31 days; P < 0.01). No major complications were observed in LL, while five ureteral perforations were encountered in PL. CONCLUSIONS: Laser lithotripsy has advantages over PL in high efficiency of stone fragmentation and a low complication rate. Laser lithotripsy is a powerful, effective, and safe treatment modality for ureteral calculi.
Adolescent↗
CordyMax Cs-4 improves steady-state bioenergy status in mouse liver.
OBJECTIVE: To evaluate effects of CordyMax Cs-4, a mycelial fermentation product of Cordyceps sinensis, on energy metabolism. DESIGN: An in vivo pharmacology study using 31P nuclear magnetic resonance (NMR) spectroscopy. SUBJECTS AND STUDY INTERVENTIONS: Adult male C57-BL/6 mice were given an aqueous extract of CordyMax, 200 or 400 mg/kg per day or placebo for 7 days. OUTCOME MEASUREMENTS: Using 31P-NMR spectroscopy to measure cellular triphosphates and inorganic phosphate, expressed as a ratio to a reference peak, and calculate tissue pH. RESULTS: Steady-state beta adenosine triphosphate (ATP) increased in the liver of mice that received CordyMax (200 or 400 mg/kg per day) for 7 days, by 12.3% +/- 0.8% and 18.4% +/- 0.9%, respectively, compared to placebo controls (both p < 0.001), suggesting a higher hepatic bioenergy status in CordyMax-treated animals. Hepatic inorganic phosphate (Pi) decreased by 24.5% +/- 0.9% and 17.6% +/- 1.7% in the two treatment groups, respectively, compared to placebo controls (p < 0.001). The ratio of beta-ATP:Pi increased by 47.7% +/- 1.6% and 41.4% +/- 2.4%, respectively, in the treatment groups (both p < 0.001 compared to placebo). After discontinuation of CordyMax for 7 days, beta-ATP and Pi returned towards baseline. CONCLUSION: CordyMax is effective in improving bioenergy status in the murine liver, suggesting a mechanism underlying the known clinical effectiveness of CordyMax in alleviating fatigue and improving physical endurance, especially in elderly subjects.
Adenosine Triphosphate↗
Blood flow decrease induces apoptosis of endothelial cells in previously dilated arteries resulting from chronic high blood flow.
We investigated apoptosis of endothelial cells during the arterial narrowing process in response to reduction in flow. The decrease in flow was created in the carotid artery by closure of an arteriovenous fistula (AVF), which had been established for 28 days in rabbits. The endothelial cell apoptosis in the carotid artery was studied at 1, 3, 7, and 21 days of flow reduction after closure of the AVF by use of terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) with laser scanning confocal microscopy and transmission and scanning electron microscopy. After AVF closure, arterial lumen diameter was reduced by 36%, and compared with endothelial cells before the closure, the number of endothelial cells was decreased by 45% at 21 days. Endothelial cell apoptosis was observed at 1 day, peaked at 3 days (381.3+/-87.1 cells per square millimeter), and decreased at 7 days. These cells had irregular protrusions under scanning electron microscopy and were characterized by fragmented nuclei under transmission electron microscopy. Apoptotic cells were mainly beneath the endothelium and were occasionally within smooth muscle cells and endothelial cells. The results suggest that apoptosis of endothelial cells may play a role in the arterial remodeling in response to a reduction in flow.
Animals↗
DNA sequencing by hybridization with arrays of samples or probes.
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Oligonucleotide Array Sequence Analysis↗
Photosensitization of the sunscreen octyl p-dimethylaminobenzoate by UVA in human melanocytes but not in keratinocytes.
Sunscreens penetrate human epidermis and modify the biology of proliferating cells. This study addressed the question whether the UV response of cultured human cells is affected by direct treatment with nontoxic levels of sunscreens. Cell survival following exposure to UVC or unfiltered UBV was not altered by preincubation with 25 micrograms/mL of octyl p-dimethylaminobenzoate (o-PABA), 2-ethylhexyl p-methoxycinnamate (EHMC) or oxybenzone. However, UVA or UVB filtered to reproduce the solar UV spectrum penetrating to the basal layer of the epidermis, highly sensitized cells to killing by o-PABA but not by its hydrolysis product, 4-dimethylaminobenzoic acid. Sensitization was found in all cell types tested, except normal keratinocytes, and could be prevented by certain antioxidants particularly pyruvate and the hydroxyl radical scavenger mannitol. o-PABA and EHMC applied without UV reduced the adherence of cells. The results indicate that sunscreens may increase cell mobility and the combination of o-PABA with solar UV may selectively damage melanocytes in the skin.
4-Aminobenzoic Acid↗
Fluorescence determination of hydrogen peroxide using hemoglobin as a mimetic enzyme of peroxidase.
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Animals↗
Amphetamine normalizes the electrical activity of dopamine neurons in the ventral tegmental area following prenatal ethanol exposure.
Prenatal ethanol exposure has been shown to produce a persistent reduction in the spontaneous activity of ventral tegmental area (VTA) dopamine (DA) neurons and in DA neurotransmission. Amphetamine-like stimulants are effective in treating attention deficit/hyperactivity disorder (ADHD), which is a major symptom in fetal alcohol syndrome. Because there is a link between reduced DA neurotransmission and ADHD, we investigated the possibility that amphetamine could restore the spontaneous activity of VTA DA neurons. Pregnant rats were administered 0 or 6 g/kg/day ethanol via intragastric intubation during gestation days 8 to 20. The spontaneous activity of VTA neurons was studied in 6- to 8-week-old male offspring using extracellular single-unit recording in unanesthetized (paralyzed, locally anesthetized) or chloral hydrate-anesthetized rats. Prenatal ethanol exposure reduced the number of spontaneously active DA neurons without changing the firing rate or firing pattern in both groups of animals. Acute amphetamine administration (2 mg/kg, i.v.) increased the number of spontaneously active DA neurons after prenatal ethanol exposure. Because amphetamine inhibited DA neuron firing rate in ethanol-exposed animals, it is possible that amphetamine restored the number of spontaneously active neurons by alleviating the depolarization block. These results show that the reduction in the number of spontaneously active DA neurons resulting from prenatal ethanol exposure is not confounded by using general anesthesia. Furthermore, acute amphetamine treatment can normalize the activity of DA neurons after prenatal ethanol exposure. This mechanism may contribute to the therapeutic effects of amphetamine-like stimulants in attention problems observed in children with fetal alcohol syndrome.
Action Potentials↗