Biomedical subjects

Yan Lu

Publications and source records attributed to Yan Lu.

At least 73 records · Page 4Linked to original sources

PubMed2005

A critical role for enhanced TGF-alpha and EGFR expression in the initiation of parathyroid hyperplasia in experimental kidney disease.

The parathyroid hyperplasia secondary to kidney disease is associated with enhanced expression of the growth promoter transforming growth factor-alpha (TGF-alpha). TGF-alpha stimulates growth through activation of its receptor, the epidermal growth factor receptor (EGFR), normally expressed in the parathyroid glands. Because enhanced coexpression of TGF-alpha and EGFR causes aggressive cellular growth, these studies utilized highly specific inhibitors of EGFR tyrosine kinase, a step mandatory for TGF-alpha-induced EGFR activation, to assess the contribution of growth signals from enhanced expression of TGF-alpha exclusively or both TGF-alpha and EGFR to the rapid parathyroid growth induced by kidney disease and exacerbated by high-phosphorus (P) and low-calcium (Ca) diets in rats. The enhancement in parathyroid gland weight and proliferating activity (proliferating cell nuclear antigen/Ki67) induced by kidney disease and aggravated by either high P or low Ca intake, within the first week after 5/6 nephrectomy, in rats, coincided with simultaneous increases (2- to 3-fold) in TGF-alpha and EGFR content. Conversely, prevention of the increases in both TGF-alpha and EGFR paralleled the efficacy of either P restriction or high-Ca intake in ameliorating uremia-induced parathyroid hyperplasia. More importantly, suppression of TGF-alpha/EGFR signaling, through prophylactic administration of potent and highly selective inhibitors of ligand-induced EGFR activation, completely prevented both high-P- and low-Ca-induced parathyroid hyperplasia as well as TGF-alpha self-upregulation. Thus enhanced parathyroid TGF-alpha/EGFR expression, self-upregulation, and growth signals occur early in kidney disease, are aggravated by low-Ca and high-P intake, and constitute the main pathogenic mechanism of the severity of parathyroid hyperplasia.

Animals↗

PubMed2005

A novel pathophysiological mechanism for osteoporosis suggested by an in vivo gene expression study of circulating monocytes.

Bone mineral density (BMD) is a major risk factor for osteoporosis. Circulating monocytes may serve as early progenitors of osteoclasts and produce a wide variety of factors important to bone metabolism. However, little is known about the roles of circulating monocytes in relation to the pathophysiology of osteoporosis. Using the Affymetrix HG-U133A GeneChip(R) array, we performed a comparative gene expression study of circulating monocytes in subjects with high and low BMD. We identified in total 66 differentially expressed genes including some novel as well as some already known to be relevant to bone metabolism. Three genes potentially contributing to bone metabolism, CCR3 (chemokine receptor 3), HDC (histidine decarboxylase, i.e. the histamine synthesis enzyme), and GCR (glucocorticoid receptor), were confirmed by quantitative real-time reverse transcriptase-PCR as up-regulated in subjects with lower BMD. In addition, significant negative correlation was observed between expression levels of the genes and BMD Z-scores. These three genes and/or their products mediate monocyte chemotaxis, histamine production, and/or sensitivity to glucocorticoids. Our results suggest a novel pathophysiological mechanism for osteoporosis that is characterized by increased recruitment of circulating monocyte into bone, enhanced monocyte differentiation into osteoclasts, as well as osteoclast stimulation via monocyte functional changes. This is the first in vivo microarray study of osteoporosis in humans. The results may contribute to identification of new genes and their functions for osteoporosis and suggest genetic markers to discern individuals at higher risk to osteoporosis with an aim for preventive intervention and treatment.

Aged↗

PubMed2005

Glutamate receptors within the nucleus of solitary tract contribute to pancreatic secretion stimulated by intraduodenal hypertonic saline.

It is well known that central transmission of vago-vagal reflex within the nucleus of solitary tract (NST) plays an important role in the regulation of gastrointestinal functions. The present study was designed to assess the role of NST glutamate receptor mechanism in pancreatic secretion evoked by intraduodenal hypertonic saline (HS) in anesthetized rats. Intraduodenal infusion of HS significantly (P<0.01) stimulated pancreatic protein output (from 2.60+/-0.09 to 4.18+/-0.24 mg/15 min). Bilaterally microinjected L-glutamate (5 nmol) into the medial nucleus of solitary tract (mNST) produced a significant increase of pancreatic protein secretion (from 2.65+/-0.12 to 4.80+/-0.34 mg/15 min, P<0.01). Bilateral injection of glutamate receptor antagonist kynurenic acid (KYN, 5 nmol) into the mNST completely abolished the increase of pancreatic protein output stimulated by intraduodenal HS (from 4.28+/-0.21 to 2.83+/-0.19 mg/15 min). Either NMDA receptor antagonist dl-2-amino-5-phosphonopentanoic acid (AP5, 1.5 nmol) or AMPA/Kainate receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX, 1.5 nmol) injected into the mNST markedly attenuated (P<0.05) the pancreatic protein secretion stimulated by intraduodenal HS. In conclusion, these findings showed that blockade of the NST glutamate receptors, including NMDA and AMPA/Kainate receptors antagonized pancreatic secretion evoked by intraduodenal osmolality factor, and suggested that glutamate receptor mechanism within the NST contributed to the central regulation of pancreatic secretion.

6-Cyano-7-nitroquinoxaline-2,3-dione↗

PubMed2005

Rainbow trout (Oncorhynchus mykiss) brain cells biosynthesize novel docosahexaenoic acid-derived resolvins and protectins-Mediator lipidomic analysis.

Docosahexaenoic acid (DHA; C22:6 n-3) is an abundant fatty acid in fish phospholipids. In the present study, we employed liquid chromatography-ultraviolet spectrometry-tandem mass spectrometry and dissociated rainbow trout (Oncorhynchus mykiss) brain cells to determine whether fish utilize endogenous DHA to produce the recently uncovered novel lipid mediators termed the resolvins and protectins, generated by mammalian cells [Serhan CN, Hong S, Gronert K, et al. Resolvins: a family of bioactive products of omega-3 fatty acid transformation circuits initiated by aspirin treatment that counter proinflammation signals. J Exp Med 2002; 196:1025-37; Hong S, Gronert K, Devchand P, Moussignac R-L, Serhan, CN. Novel docosatrienes and 17S-resolvins generated from docosahexaenoic acid in murine brain, human blood, and glial cells. J Biol Chem 2003;278:14677-87]. Trout brain cells biosynthesize a range of recently identified di- and tri-hydroxy-containing bioactive products from endogenous sources of DHA when challenged in vitro. We identified neuroprotectin D1, resolvin D5, resolvin D1 and resolvin D2 from trout brain cells. Each compound was identified on the basis of its characteristic physical chemical properties that included MS, MS-MS, UV spectra and chromatographic behavior. The monohydroxy products from DHA, signatures of DHA conversion by lipoxygenases, were also identified. These included both 14S-hydroxy-docosahexaenoic acid and 17S-hydroxy-docosahexaenoic acid. The biosynthesis of these novel bioactive lipid mediators, namely resolvins and protectins, by fish cells provides the first evidence for the conservation of these structures from fish to humans as chemical signals in diverse biological systems.

Animals↗

PubMed2005

Association tests of interleukin-6 (IL-6) and type II tumor necrosis factor receptor (TNFR2) genes with bone mineral density in Caucasians using a re-sampling approach.

Interleukin 6 (IL-6) and tumor necrosis factor (TNF) are important cytokines for bone turnover. In this study, a promoter C-174G single-nucleotide polymorphism (SNP) within the IL-6 gene affecting the transcription rate of IL-6 and an exon 6 T676G SNP of the TNF receptor 2 (TNFR2) gene causing an M196R amino-acid change were examined for their relationship with bone mineral density (BMD). Four hundred and five multi-offspring Caucasian families, including 389 male children and 744 female children, were used. One thousand re-samplings were conducted and in each data set, one child was randomly chosen from each family. For each data set, one-way analysis of variance (ANOVA) test was independently implemented using age, age2, sex, height and weight as covariates. There were 523, 288, 204 and 369 significant results out of 1,000-replicate re-samplings of the data of the IL-6 SNP (P<0.05) for one-third, mid-distal, ultradistal radius BMD, and the first principal component (PC1) extracted from the three radial BMDs, respectively, which means that the confidences for associations of the C-174G SNP in the IL-6 gene with one-third, mid-distal, ultradistal radius (totally called distal forearm) BMDs, and PC1, were 52.3, 28.8, 20.4 and 36.9%, respectively. For this SNP with BMD at other skeletal sites and the TNFR2 T676G SNP with BMD at any site, significant results were far less than 200 times out of 1,000 re-sampling replicates. The exceedingly consistent permutation results further improved the confidence of the associations. It may imply that the IL-6 C-174G SNP is associated with distal forearm BMD, but there is no evidence that the TNFR2 T676G SNP is related with BMD in US Caucasians. This is the first attempt to conduct association test utilizing a re-sampling approach. Our results may be more informative than other association analyses that were only based on one sampling result. The results also suggest that different samplings could produce significantly diverse results even for the same population and the results from one sampling are unlikely to be conclusive. Our results have significant implications for association studies and interpretation of non-reproducible association findings.

Body Weights and Measures↗

PubMed2005

Hotelling's T2 multivariate profiling for detecting differential expression in microarrays.

The most widely used statistical methods for finding differentially expressed genes (DEGs) are essentially univariate. In this study, we present a new T(2) statistic for analyzing microarray data. We implemented our method using a multiple forward search (MFS) algorithm that is designed for selecting a subset of feature vectors in high-dimensional microarray datasets. The proposed T2 statistic is a corollary to that originally developed for multivariate analyses and possesses two prominent statistical properties. First, our method takes into account multidimensional structure of microarray data. The utilization of the information hidden in gene interactions allows for finding genes whose differential expressions are not marginally detectable in univariate testing methods. Second, the statistic has a close relationship to discriminant analyses for classification of gene expression patterns. Our search algorithm sequentially maximizes gene expression difference/distance between two groups of genes. Including such a set of DEGs into initial feature variables may increase the power of classification rules. We validated our method by using a spike-in HGU95 dataset from Affymetrix. The utility of the new method was demonstrated by application to the analyses of gene expression patterns in human liver cancers and breast cancers. Extensive bioinformatics analyses and cross-validation of DEGs identified in the application datasets showed the significant advantages of our new algorithm.

Algorithms↗

PubMed2005

Linkage and association analyses of the UCP3 gene with obesity phenotypes in Caucasian families.

Uncoupling protein 3 (UCP3) uncouples ATP production from mitochondrial respiration, thereby dissipating energy as heat and affecting the efficiency of energy metabolism. Genetic variations in the UCP3 gene have been conceived to affect body weight in the general population. In this study, using the quantitative transmission disequilibrium test (QTDT), we assessed linkage and association between the UCP3 gene and obesity phenotypes in a large sample of 1,873 subjects from 405 United States Caucasian nuclear families. Obesity phenotypes tested include body mass index (BMI), fat mass, percent fat mass (PFM), and lean mass, with the latter three measured by dual-energy X-ray absorptiometry. We first selected five single nucleotide polymorphisms (SNPs) and then analyzed three highly polymorphic ones, namely, -55 C/T (promoter), Tyr99Tyr (exon 3), and Tyr210Tyr (exon 5), in the total sample. Significant linkage disequilibria (0.392 <or= D' <or= 0.940, P < 0.0001) were observed between pairs of SNPs. In single-locus analyses, we found statistically significant association (P = 0.034) and linkage (P = 0.031) between -55 C/T and BMI. This polymorphism explains 2.29% of BMI variation, and subjects carrying the T allele had an average of 3.5% lower BMI than those without it (P = 0.003). In haplotype analyses, we also observed evidence of linkage (P = 0.002) and association (P = 0.035) with BMI. In summary, our results suggest that UCP3 gene polymorphisms may contribute to BMI variation in this Caucasian population.

Alleles↗

PubMed2005

Expression analysis of secreted and cell surface genes of five transformed human cell lines and derivative xenograft tumors.

BACKGROUND: Since the early stages of tumorigenesis involve adhesion, escape from immune surveillance, vascularization and angiogenesis, we devised a strategy to study the expression profiles of all publicly known and putative secreted and cell surface genes. We designed a custom oligonucleotide microarray containing probes for 3531 secreted and cell surface genes to study 5 diverse human transformed cell lines and their derivative xenograft tumors. The origins of these human cell lines were lung (A549), breast (MDA MB-231), colon (HCT-116), ovarian (SK-OV-3) and prostate (PC3) carcinomas. RESULTS: Three different analyses were performed: (1) A PCA-based linear discriminant analysis identified a 54 gene profile characteristic of all tumors, (2) Application of MANOVA (Pcorr < .05) to tumor data revealed a larger set of 149 differentially expressed genes. (3) After MANOVA was performed on data from individual tumors, a comparison of differential genes amongst all tumor types revealed 12 common differential genes. Seven of the 12 genes were identified by all three analytical methods. These included late angiogenic, morphogenic and extracellular matrix genes such as ANGPTL4, COL1A1, GP2, GPR57, LAMB3, PCDHB9 and PTGER3. The differential expression of ANGPTL4 and COL1A1 and other genes was confirmed by quantitative PCR. CONCLUSION: Overall, a comparison of the three analyses revealed an expression pattern indicative of late angiogenic processes. These results show that a xenograft model using multiple cell lines of diverse tissue origin can identify common tumorigenic cell surface or secreted molecules that may be important biomarker and therapeutic discoveries.

Analysis of Variance↗

PubMed2005

Modular organization of excitatory circuits between neurons of the spinal superficial dorsal horn (laminae I and II).

Neural circuitry of the spinal superficial dorsal horn (SDH) (laminae I and II) and its relationship to pain and other somatosensory phenomena remain poorly understood. To gain information on this issue, synaptic connections between identified SDH neurons were studied in rat spinal cord slices by simultaneous whole-cell recordings from pairs of cells. Both excitatory and inhibitory connections were noted. This report focuses on the observed excitatory linkages. Synaptic excitatory connections between SDH neurons proved highly selective and consistently were unidirectional. Two patterns repeatedly appeared (for neuron classification, see Materials and Methods) (Grudt and Perl, 2002). Lamina II central neurons, with dorsal root (DR) C-fiber input, monosynaptically excited lamina II vertical neurons with DR Adelta input. Lamina II outer vertical neurons with DR Adelta input monosynaptically excited lamina I neurons. Some of the postsynaptic lamina I cells were shown to project rostrally. In contrast to the usual case for connected neurons, in unconnected pairs, primary afferent input to the same type of neuron proved closely similar. Together, these observations indicate that the neural circuitry in the SDH, including its substantia gelatinosa (lamina II), has an explicit organization in which particular combinations of neurons comprise modules arranged to modify and transmit sensory information arriving from Adelta and C primary afferent fibers.

6-Cyano-7-nitroquinoxaline-2,3-dione↗

PubMed2005

RAGE limits regeneration after massive liver injury by coordinated suppression of TNF-alpha and NF-kappaB.

The exquisite ability of the liver to regenerate is finite. Identification of mechanisms that limit regeneration after massive injury holds the key to expanding the limits of liver transplantation and salvaging livers and hosts overwhelmed by carcinoma and toxic insults. Receptor for advanced glycation endproducts (RAGE) is up-regulated in liver remnants selectively after massive (85%) versus partial (70%) hepatectomy, principally in mononuclear phagocyte-derived dendritic cells (MPDDCs). Blockade of RAGE, using pharmacological antagonists or transgenic mice in which a signaling-deficient RAGE mutant is expressed in cells of mononuclear phagocyte lineage, significantly increases survival after massive liver resection. In the first hours after massive resection, remnants retrieved from RAGE-blocked mice displayed increased activated NF-kappaB, principally in hepatocytes, and enhanced expression of regeneration-promoting cytokines, TNF-alpha and IL-6, and the antiinflammatory cytokine, IL-10. Hepatocyte proliferation was increased by RAGE blockade, in parallel with significantly reduced apoptosis. These data highlight central roles for RAGE and MPDDCs in modulation of cell death-promoting mechanisms in massive hepatectomy and suggest that RAGE blockade is a novel strategy to promote regeneration in the massively injured liver.

Animals↗

PubMed2005

Mediator-lipidomics: databases and search algorithms for PUFA-derived mediators.

Lipid mediators (LMs) derived from PUFAs play important roles in health and disease. Databases and search algorithms are crucial, but currently unavailable, for accurate and prompt analysis of LMs via liquid chromatography-ultraviolet-tandem mass spectrometry (LC-UV-MS/MS). A novel algorithm and databases, cognoscitive-contrast-angle algorithm and databases (COCAD), were developed for the identification of LMs based on the integration of standard MS/MS spectra with chromatograms and UV spectra. Segment naming and empirical fragmentation rules were introduced to determine MS/MS ion identities, along with ion intensities used by COCAD in matching the unknown to those of authentic standards. The structures of potential LMs without synthetic and/or authentic products as standards were identified by developing theoretical databases and algorithms based on virtual LC-UV-MS/MS spectra and chromatograms. The performance of these databases and algorithms was tested by identifying LMs in murine tissues. These results indicate that COCAD has many advantages for profiling and identification of LMs compared with the conventional dot-product algorithm.

Algorithms↗

PubMed2005

Functional identification of kinases essential for T-cell activation through a genetic suppression screen.

Activation of T-cells by antigens initiates a complex series of signal-transduction events that are critical for immune responses. While kinases are key mediators of signal transduction networks, several of which have been well characterized in T-cell activation, the functional roles of other kinases remain poorly defined. To address this deficiency, we developed a genetic screen to survey the functional roles of kinases in antigen mediated T-cell activation. A retroviral library was constructed that expressed genetic suppressor elements (GSEs) comprised of peptides and antisense nucleotides derived from kinase cDNAs including members of the STE, CAMK, AGC, CMGC, RGC, TK, TKL, Atypical, and Lipid kinase groups. The retroviral library was expressed in Jurkat T-cells and analyzed for their effect on T-cell activation as monitored by CD69 expression. Jurkat cells were activated by antigen presenting cells treated with superantigen, and sorted for a CD69 negative phenotype by flow cytometry. We identified 19 protein kinases that were previously implicated in T-cell signaling processes and 12 kinases that were not previously linked to T-cell activation. To further validate our approach, we characterized the role of the protein kinase MAP4K4 that was identified in the screen. siRNA studies showed a role for MAP4K4 in antigen mediated T-cell responses in Jurkat and primary T-cells. In addition, by analyzing multiple promoter elements using reporter assays, we have shown that MAP4K4 is implicated in the activation of the TNF-alpha promoter. Our results suggest that this methodology could be used to survey the function of the entire kinome in T-cell activation.

Antigens, CD↗

PubMed2005

E-cadherin gene C-160A promoter polymorphism and risk of non-cardia gastric cancer in a Chinese population.

AIM: To test the hypothesis that E-cadherin gene (CDH1) C-160A promoter variant genotype is associated with an increased risk for developing gastric cancer. METHODS: In this population-based case-control study of gastric cancer in Jiangsu Province, China, we performed polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) to genotype the C-160A polymorphism of CDH1 promoter in 206 non-cardia gastric cancer patients and 261 age- and sex-matched but unrelated cancer-free controls. RESULTS: The frequencies of genotypes CC, CA and AA were 57.8%, 36.4% and 5.8% in gastric cancer cases, respectively, and 58.2%, 34.9% and 6.9% in controls respectively. The distributions of CDH1 genotypes were not significantly different between gastric cancer cases and controls (P = 0.87 for genotype frequency and P = 0.92 for allele frequency). Compared with the CC genotype, the CA and AA genotypes were not associated with an increased risk for non-cardia gastric cancer (adjusted odds ratios (OR) = 1.15, and 95% confidence interval (95% CI) = 0.78-1.72 for CA genotype, and OR = 0.90 and 95% CI = 0.42-2.01 for AA genotype). CONCLUSION: E-cadherin gene C-160A promoter polymorphism may not play a major role in the etiology of non-cardia gastric cancer in Chinese population.

Adult↗

PubMed2005

Effects of Rebixiao granules on blood uric acid in patients with repeatedly attacking acute gouty arthritis.

OBJECTIVE: To observe the clinical effect of Rebixiao granule (RBXG) in treating repeatedly attacking acute gouty arthritis and through experimental study on blood uric acid to explore RBXG's therapeutic mechanism. METHODS: Ninety repeatedly attacking acute gouty arthritis patients were divided into the treated group (n = 60) and control group (n = 30). The treated group was treated with RBXG, and the control group was treated with Futalin tablets (diclofenac sodium). The baseline treatment including good rest, low purine diet, sufficient water drinking and urine alkalization, etc. was then given to both groups. Hypoxanthine 600 mg/kg and niacin 100 mg/kg was applied to hyperuricemic mice by gastrogavage to establish the animal models. RESULTS: The clinical effective rate of the treated group was 95.0% and that of the control 90.0%. Good therapeutic effects were won, insignificant difference (P > 0.05)was shown between the two groups. However, the cure rate of the treated group was 26.7% while that of the control group was 10.0%, with significant difference (P < 0.01) shown between them. The treated group had its blood uric acid lowered, which was significantly different (P < 0.05) from that of the control group. The animal experiment indicated that all the three groups treated with different dosages of RBXG, as well as the Ash bark and Smilax glabra rhizome groups had their blood uric acid content reduced in the hyperuricemic mice. CONCLUSION: RBXG has a quicker initiation and better treatment effects than sole anti-inflammatory and analgesic agents on the treatment of repeatedly attacking acute gouty arthritis, showing no obvious toxic or adverse reactions and therefore good for long-term administration and likely to be a safe TCM preparation to control the symptoms and reduce the onsets of repeatedly attacking of acute gouty arthritis. The animal experiment shows that both the compound preparation and part of the single ingredients in the recipe have the function of reducing blood uric acid. However, the compound recipe has better therapeutic effects, proving to be superior to single drugs.

Acute Disease↗

PubMed2005

Effect of simulated shoulder thermal capsulorrhaphy using radiofrequency energy on glenohumeral fluid temperature.

PURPOSE: To determine joint fluid temperatures at different time intervals during treatment with radiofrequency energy (RFE) applied in intermittent and continuous treatment manners under flow or no-flow conditions using a simulated shoulder joint model. TYPE OF STUDY: In vitro measurement of simulated joint fluid temperature during RFE treatment. METHODS: A custom-built jig with a chamber (volume size, 25 mL) was used to mimic the adult human shoulder. Three RFE systems: Vulcan EAS plus TAC-S probe (Smith & Nephew Endoscopy, Andover, MA); VAPR II plus End-Effect Electrode (Mitek, Westwood, MA); and ArthroCare 2000 plus TurboVac 90 degrees probe (ArthroCare, Sunnyvale, CA) were tested in the chamber with saline solution initially set at 23 degrees C. Each RFE probe was applied in a paintbrush pattern on the capsular tissue in the chamber and a fluoroptic thermometry probe was placed 1 cm above the RFE treatment probe to record the fluid temperature. Both intermittent and the continuous treatment manners were tested under flow and no-flow conditions. For each probe/manner/flow combination, 6 bovine capsular tissue specimens were tested (n = 6). All data were recorded using a HyperTerminal software program (Hilgraeve Inc, Monroe, MI) into a personal computer. RESULTS: When using intermittent and continuous treatment manners with flow, all recorded chamber fluid temperatures for all tested RFE probes at each time interval were below 40 degrees C. Under no-flow conditions, with intermittent treatment, the ArthroCare probe caused joint fluid temperatures to exceed 50 degrees C after 70 seconds of RFE treatment. With the continuous treatment, the ArthroCare caused chamber fluid temperatures to exceed 65 degrees C after 2 minutes of treatment. The highest mean recorded chamber fluid temperature was caused by ArthroCare probe, which reached 80 degrees C at 3 minutes. For all probes, continuous treatment caused significantly higher chamber fluid temperatures than intermittent treatment. CONCLUSIONS: The results of this study indicate that using flow during thermal capsulorrhaphy could lower joint fluid temperature to prevent heated joint fluid from killing chondrocytes of articular cartilage, and the intermittent treatment manner caused lower fluid temperature compared with continuous treatment within the RFE-treated shoulder joint. CLINICAL RELEVANCE: Articular cartilage of the humeral head may suffer potential thermal injury from heating of joint fluid during RFE thermal capsulorrhaphy.

Animals↗

PubMed2005

In vivo transplantation of neonatal ovine neocartilage allografts: determining the effectiveness of tissue transglutaminase.

Following transplantation of ovine neocartilage allografts, 26 sheep were divided into groups according to the following weight-bearing schedule: 8-week nonweight bearing (8NWB, n=14), and 8-week nonweight bearing+4-week weight bearing (8NWB+4WB, n=12). In addition, 7 and 6 sheep, respectively, in the 8NWB and 8NWB+4WB groups received tTG treatment after allograft transplantation, whereas the remaining 13 sheep in these groups did not receive tTG. Finally, 8 sheep served as sham-operated controls without allograft transplantation. After euthanasia, stifle joints were harvested for the analysis of gross appearance, chondrocyte viability, histology, and biomechanical testing. No significant differences were noted in macroscopic graft survival and union with host tissue in both 8NWB and 8NWB+4WB groups between the tTG treated and non-tTG treated animals. Analysis of histological scores demonstrated no significant difference between tTG and non-tTG treatments in both 8NWB and 8NWB+4WB groups. Confocal laser microscopic analysis of the explanted defects revealed 70%-100% cell viability in all treatment groups. This study shows that allogeneic chondrocytes harvested from neonatal donors provide sufficient metabolic activity to affect repair. Use of tTG to augment resorbable suture fixation of neocartilage grafts provided no advantage over suture alone in this pilot study.

Animals↗

PubMed2005

Blood pressure responses of endothelin-1 1-31 within the rostral ventrolateral medulla through conversion to endothelin-1 1-21.

Endothelin-1 1-31 (ET-1 1-31), a novel member of the endothelin family comprising 31 amino acids and derived from the selective hydrolysis of big ET-1 by chymase, directly activates endothelin receptors or converts to ET-1 1-21 by ET converting enzyme (ECE). The cardiovascular effects of central ET-1 1-31 are not identified. The present study was designed to investigate the cardiovascular actions of ET-1 1-31 within the rostral ventrolateral medulla (RVLM) in anesthetized rats. Bilateral injection of ET-1 1-31 (0.5, 1, and 2 pmol for each side) into the rostral ventrolateral medulla produced an initial pressor and/or a long-lasting hypotensive action but did not affect HR. Unilateral microinjection of 2 and 4 pmol of ET-1 1-31 into the rostral ventrolateral medulla only produced a significant (P < 0.05) transient increase in blood pressure by an average of 13 and 12 mm Hg, respectively, whereas unilateral microinjection of 8 pmol of ET-1 1-31 produced a sustained fall in blood pressure (from 92 +/- 6 to 69 +/- 8 mm Hg, P < 0.05). The transient pressor effect of unilaterally injecting ET-1 1-31 (4 pmol) into the rostral ventrolateral medulla was completely abolished by pretreatment with either ETA receptor antagonist BQ123 (83 +/- 2 versus 84 +/- 5 mm Hg, P > 0.05) or ET converting enzyme inhibitor phosphoramidon (99 +/- 5 versus 99 +/- 7 mm Hg, P > 0.05) but not ETB receptor antagonist IRL1038 (89 +/- 6 versus 96 +/- 7 mm Hg, P < 0.05). In addition, prior injection of phosphoramidon also completely abolished the long-lasting hypotension of intra-RVLM ET-1 1-31 (8 pmol) but did not modify the depressor action of intra-RVLM ET-1 1-21 (from 100 +/- 6 to 76 +/- 8 mm Hg, P < 0.05). In conclusion, the current results suggest that the cardiovascular effects of intra-RVLM ET-1 1-31 might be the result of conversion of ET-1 1-31 to ET-1 1-21 through activation of ETA receptors.

Animals↗

PubMed2005

Effects of radiofrequency energy on human chondromalacic cartilage: an assessment of insulation material properties.

The objective of this study was to establish guidelines for the selection of an insulation material used to surround the electrode of radiofrequency energy (RFE) probes used for thermal chondroplasty. These guidelines were established by identifying which insulation materials resulted in the least amount of chondrocyte death while smoothing the surface of chondromalacic cartilage. RFE causes electrolyte oscillation and molecular friction in the tissue to heat it and subsequently smooth the surface. Material properties investigated included the coefficient of thermal expansion (CTE), thermal conductivity (TC), and volume resistivity (VR). Fresh human chondromalacic cartilage samples of Outerbridge grades II and III were obtained from patients undergoing total knee arthroplasty. Stiffness measurements were taken pretreatment and posttreatment. RFE was applied to a 1-cm2 area for 15 s in a paintbrush treatment pattern. The insulation materials evaluated included Macor (decrease CTE, decrease TC, increase VR; in relation to CTE = 10 x 10(-6)/degrees C at 20 degrees C, TC = 3 W/mK, VR=1 x 10(14) ohm x cm), zirconia toughened alumina (ZTA) and 99.5% alumina (decrease CTE, increase TC, increase VR), aluminum nitride (decrease CTE, increase TC, decrease VR), Teflon (PTFE) (increase CTE, decrease TC, increase VR), partially stabilized zirconia (YTZP) (decrease CTE, decrease TC, decrease VR), and Ultem (increase CTE, decrease TC, decrease VR). There were no significant differences between pretreatment and posttreatment stiffness of the cartilage for any material investigated. Subjectively scored scanning electron microscopy (SEM) images revealed that the surfaces of all samples treated with RFE were relatively smooth with melted fronds. Prototype probes made with Macor, 99.5% alumina, and ZTA had TC < or = 30 W/mol x K and resulted in a mean of 35% less cell death (176+/-56 microm, 130+/-48 microm, and 114+/-33 microm, respectively) than aluminum nitride, PTFE, and YTZP (246+/-68 microm, 231+/-108 microm, and 195+/-89 microm, respectively). Macor, 99.5% alumina, and ZTA prototype probes all had VR > or = 1 x 10(14) ohm x cm and resulted in a mean 37% less cell death than aluminum nitride or YTZP. There was no apparent relationship between CTE and the depth of chondrocyte death.

Biocompatible Materials↗