Biomedical subjects

J S Sun

Publications and source records attributed to J S Sun.

At least 55 records · Page 3Linked to original sources

PubMed1998

Rational design of a triple helix-specific intercalating ligand.

DNA triple helices offer new perspectives toward oligonucleotide-directed gene regulation. However, the poor stability of some of these structures might limit their use under physiological conditions. Specific ligands can intercalate into DNA triple helices and stabilize them. Molecular modeling and thermal denaturation experiments suggest that benzo[f]pyrido[3, 4-b]quinoxaline derivatives intercalate into triple helices by stacking preferentially with the Hoogsteen-paired bases. Based on this model, it was predicted that a benzo[f]quino[3,4-b]quinoxaline derivative, which possesses an additional aromatic ring, could engage additional stacking interactions with the pyrimidine strand of the Watson-Crick double helix upon binding of this pentacyclic ligand to a triplex structure. This compound was synthesized. Thermal denaturation experiments and inhibition of restriction enzyme cleavage show that this new compound can indeed stabilize triple helices with great efficiency and specificity and/or induce triple helix formation under physiological conditions.

Animals↗

PubMed1998

Influence of hydroxyapatite particle size on bone cell activities: an in vitro study.

Over the past decade, a large number of biomaterials have been proposed as artificial bone fillers for repairing bone defects. The material most widely used in clinical medicine is hydroxyapatite. The aim of our investigation was to study the effect of hydroxyapatite size mechanism on osteoblasts. The osteoblasts were cultured in vitro with 0.1% (1 mg/mL) of various sized hydroxyapatite particles (0.5-3.0, 37-63, 177-250, and 420-841 microm) for 1 h, 3 h, 1 day, 3 days, and 7 days. The results showed that adding hydroxyapatite particles to osteoblast cultures can significantly affect osteoblast cell count. Osteoblast populations decreased significantly. Osteoblast mean surface areas also changed significantly. Transforming growth factor-beta1 (TGF-beta1) concentrations in culture medium decreased significantly with the addition of hydroxyapatite particles. Prostaglandin E2 (PGE2) concentrations in medium increased significantly. The changes in TGF-beta1 and PGE2 concentration were more significant and persisted longer in smaller-particle groups. The inhibitory effects of hydroxyapatite particles on osteoblast cell cultures were mediated by the increased synthesis of PGE2. Caution should be exercised before using a hydroxyapatite product which could easily break down into fine particles.

Alkaline Phosphatase↗

PubMed1998

Biological effects and cytotoxicity of the composite composed by tricalcium phosphate and glutaraldehyde cross-linked gelatin.

The purpose of this study was to prepare and evaluate the feasibility and cytocompatibility of a composite (GTG) as a large defect bone substitute. The composite is combined with tricalcium phosphate ceramic particles and glutaraldehyde cross-linked gelatin. Gelatin had been reported as an adhesive and biocompatible binder that could accelerate the recovery of damaged soft tissue, but the effects of gelatin when acting on the bone tissue is not clear. Thus, it is necessary to determine if the substances released from the GTG composite can facilitate the growth of bone cells. The substances released from the GTG composites after being soaked in deionized distilled water were analyzed by gas chromatography (GC), ultraviolet and visible absorption spectroscopy (UV-VIS), and inductive-coupled plasma-atomic emission spectrometry (ICP-AES). The cytotoxicity of the GTG composites was assessed by coculture of rat osteoblasts in vitro. Extracts were obtained by soaking the GTG composites in deionized distilled water for 1, 2, 4, 7, 14, 28 and 42 d. The extract mixed with complete medium in a ratio of 1:1 was added into the cell culture wells containing 1 x 10(4) cells ml(-1) osteoblasts. After culturing for 2 days, the cells attached to the surface of wells were trypsinized and the number calculated by the Neubauer counting-chamber under the optical microscope. Finally, three samples in each GTG group were examined by scanning electron microscopy (SEM) to observe the morphology of the osteoblasts attached to the surfaces of GTG composites. The examinations of osteoblasts cocultured with the developed GTG composites were used to decide the ideal concentration of glutaraldehyde as a cross-linking agent. The results of extracts cocultured with osteoblasts showed that the extracts obtained from the 2, 4 and 8% glutaraldehyde cross-linked GTG composites would inhibit the growth of osteoblasts in the first 4 soaking days. During the 4-7 days soaking, the cell numbers quickly increased with the soaking time, thereafter, the cell numbers almost reached a constant value. In the analyses of substances released from the GTG composites, it was found that the gelatin and calcium were gradually released from the GTG composites, which were supposed to be nutritious for the growth of the osteoblast. The results of osteoblasts cocultured with the GTG composites showed that the concentration of glutaraldehyde used as a cross-linking agent should be lower than 8%. Compared to the GTF (composite combined with tricalcium phosphate ceramic particles and formaldehyde cross-linked gelatin), GTG composites were much suitable for a large defect bone substitute in the near future.

Animals↗

PubMed1998

Preparation of high-temperature stabilized beta-tricalcium phosphate by heating deficient hydroxyapatite with Na4P2O7 x 10H2O addition.

In this paper, the high-temperature stabilized beta-tricalcium phosphate (betaTCP, beta-Ca3(PO4)2) were prepared by heating the deficient HAP (d-HAP, Ca10-x(HPO4)x(PO4)6-x(OH)2-x) with tetra-sodium diphosphate decahydrate (NP, Na4P2O7 x 10H2O) addition. The betaTCP, d-HAP and d-HAP doped with 2.5, 5, 7.5 and 10 wt % NP were heated to different temperatures and were investigated by X-ray diffraction analysis (XRD) and Fourier-transformed infrared spectroscopy (FTIR). The results demonstrated that the HPO4(2-) of d-HAP condensed into P2O7(4-) occurred before 650 degrees C. The P2O7(4-) ions could be traced in the FTIR spectrum when the d-HAP was heated up to 750 degrees C. The reaction of P2O7(4-) with OH- did not occur instantly but over a wide range of temperatures. The d-HAP doped with NP would decrease the decomposition temperature of d-HAP. NP doped into d-HAP not only induced the d-HAP decomposition at lower temperature but also stabilized the betaTCP crystal structure at higher-temperature. It could also increase the conversion temperature of betaTCP to alphaTCP from 1180 degrees C up to 1300 degrees C. We could successfully prepare high-temperature (up to 1300 C) stabilized ffTCP by heating NP doped d-HAP.

Calcium Phosphates↗

PubMed1998

Genetic organization of the HindIII-I region of the single-nucleocapsid nucleopolyhedrovirus of Buzura suppressaria.

In order to investigate the genomic organization of the single-nucleocapsid nucleopolyhedrovirus (SNPV) of Buzura suppressaria (BusuNPV), the HindIII-I fragment located at map units (mu) 26.6-29.4 of the viral genome was sequenced. The fragment contained two partial and three complete open reading frames (ORFs) representing the 3' end of a polyhedron envelope protein gene (pep), a homologue of the AcMNPV ORF117, a conotoxin-like protein gene (ctl), an inhibitor of apoptosis gene (iap) and a superoxide dismutase gene (sod), respectively. These five genes were identified for the first time in a SNPV. Sequence analysis further revealed that these ORFs have the same conserved motifs and gene structure as those observed in their homologues from other baculoviruses. Between ctl and iap, an intergenic region of about 700 basepairs with structure similar to non-hr origins of DNA replication was observed. The genomic arrangement of the ORFs in the BusuNPV HindIII-I fragment is very different from the arrangement of their homologues in the genome of Autographa californica multiple nucleocapsid (M) NPV and other baculoviruses to date. Our data suggest that on the basis of gene arrangement, BusuNPV belongs to a distinct taxon within the Baculoviridae family, corroborating our previous conclusions derived from phylogeny analysis of several BusuNPV genes.

Amino Acid Sequence↗

PubMed1998

An ultra-weak chemiluminescence study on oxidative stress in rabbits following acute thermal injury.

It is not easy to detect oxygen free radicals directly because of their very short half-life. In the present study, a sensitive ultra-weak chemiluminescence detector was used to detect the generation of oxygen free radicals following thermal injury. Twelve New Zealand white rabbits were used in this study. After anesthesia, the bilateral hind-limbs were exposed to 100 degrees C water for 30 s. Six control animals were exposed to 22 degrees C water to act as a control. The chemiluminescence of whole blood and visceral organs were measured with both luminol-amplified t-butyl hydroperoxide-initiated and lucigenin-initiated methods. The results showed that chemiluminescence of blood was affected significantly by acute thermal injury. The chemiluminescence of blood increased significantly at 1 h following acute thermal injury, reached a peak at 2 h, then decreased but still remained above the control level at 4 h following thermal injury. The results for TBHP-initiated chemiluminescence from visceral organs following acute thermal injury were much higher than that of the control rabbits. The effects of lucigenin-initiated tissue chemiluminescence following acute thermal injury were not statistically significant. It is suggested that the decreased vascular antioxidant activity following local thermal injury is partially contributed by the superoxide pathway; while, the remote pathophysiologic events are mediated by the defective scavenging defenses.

Acridines↗

PubMed1998

New junction models for alternate-strand triple-helix formation.

BACKGROUND: [corrected] Oligonucleotide-directed triple-helix (triplex) formation can interfere with gene expression but only long tracts of oligopyrimidine*oligopurine sequences can be targeted. Attempts have been made to recognize short oligopurine sequences alternating on the two strands of double-stranded DNA by the covalent linkage of two triplex-forming oligonucleotides. Here we focus on the rational optimization of such an alternate-strand triplex formation on a DNA duplex containing a 5'-GpT-3'/3'-CpA-5' or a 5'-TpG-3'/3'-ApC-5' step by combination of (G,T)- and (G,A)-containing oligonucleotides that bind to the oligopurine strands in opposite orientations. RESULTS: The deletion of one nucleotide in the reverse Hoogsteen region of the oligonucleotide provides the best binding at the 5'GpT-3'/3'-CpA-5' step, whereas the addition of two cytosines as a linker between the two oligonucleotides is the best strategy to cross a 5'-TpG-3'/3'-ApC-5' step. Energy minimization and experimental data suggest that these two cytosines are involved in the formation of two novel base quadruplets. CONCLUSIONS: These data provide a rational basis for the design of oligonucleotides capable of binding to oligopurine sequences that alternate on the two strands of double-stranded DNA with a 5'-GpT-3'/3'-CpA-5' or a 5'-TpG-3'/3'-ApC-5' step at the junction.

Base Sequence↗

PubMed1998

A UV-crosslinkable interaction in human U6 snRNA.

U6 snRNA is the most conserved of all the snRNAs involved in pre-mRNA splicing, and likely plays an important role in splicing catalysis. Using a U6 snRNA fragment encompassing residues 25-99, we have identified a strong, UV-sensitive tertiary intramolecular interaction. A 5' deletion that removed sequences up to nt 37 only slightly reduced crosslinking, but further deletion of 11 bases, eliminating the nearly invariant ACAGAGA sequence, essentially abolished crosslinking, as did deletion of sequences 3' of 82A. The crosslinked residues were mapped to 44G in the ACAGAGA sequence and to 81C, the nucleotide at the base of the U6 intramolecular helix, opposite the G of the invariant AGC trinucleotide. This interaction is striking in that it has the potential to juxtapose invariant regions of U6 believed to play critical roles in splicing catalysis.

Base Sequence↗

PubMed1998

Distinct gene arrangement in the Buzura suppressaria single-nucleocapsid nucleopolyhedrovirus genome.

The genome organization of the Buzura suppressaria single-nucleocapsid nucleopolyhedrovirus (BusuNPV) was largely elucidated and compared to those of other baculoviruses. A detailed physical map was constructed for the restriction enzymes BamHI, BglI, BglII, EcoRI, HindIII, KpnI, PstI, XbaI and XhoI. The 120.9 kbp viral genome was cloned as restriction fragments into a plasmid library from which about 43.5 kbp of dispersed sequence information was generated. Fifty-two putative open reading frames homologous to those of other baculoviruses were identified and their location in the genome of BusuNPV was determined. Although the gene content of BusuNPV is similar to that of Autographa californica multiple-nucleocapsid nucleopolyhedrovirus, Bombyx mori nucleopolyhedrovirus and Orgyia pseudotsugata multiple-nucleocapsid nucleopolyhedrovirus, the gene order is, however, significantly different from that observed in the other viruses, which have a high degree of collinearity. A new approach (GeneParityPlot) was developed to represent the differences in gene order among baculoviruses when limited sequence information is available and to take advantage of the high degree of gene conservation. The data obtained show that BusuNPV is a distinct baculovirus species and the analyses suggest that gene distribution along baculovirus genomes may be used as a phylogenetic marker.

Animals↗

PubMed1998

Biochemical and histopathological changes in the mortality caused by acute ischemic limb injury: a rabbits' model.

Restoration of blood flow to an acute ischemic extremity may deteriorate the ischemic injury, lead to multiple organ dysfunction or even death. This paradox of continuing injury during reperfusion is not completely understood. The role of multi-organ damage in the mortality caused by ischemic limb injury is also still not clarified. The purpose of this study is to determine the biochemical and histopathological changes in the mortality caused by ischemic limb injury. After anesthesia, the hindlimbs of 14 New Zealand white rabbits were made ischemic and set into 8 hours or 12 hours of ischemia. Blood samples were obtained then the creatine kinase (CK) levels were determined and CK isoenzymes analyzed. All rabbits with 8 hours' ischemia survived well, and 5 of the 7 rabbits with 12 hours' ischemia expired within 8 hours after reperfusion. CK elevation was correlated most strongly with the time of the ischemic insults. The percentage of CK-MB isoenzyme remained unchanged after 8 hours' ischemia-reperfusion insult, while increased significantly after 12 hours' ischemia-reperfusion insult. Histologic examinations showed that the major systemic manifestation was massive destruction of the liver and kidney. The injuries are more obvious in areas with the greatest blood flow during reperfusion. We concluded that the ratio of CK-MB isoenzyme is most useful for distinguishing the risk of mortality caused by acute ischemic limb injury, and the cause of systemic complications are attributed to the multi-organ failure.

Acute Disease↗

PubMed1998

Wrist arthrodesis using a slab bone graft from the dorsal radius.

Arthrodesis is a well-established procedure for the management of wrist deformity, instability, and arthritis resulting from various causes. Several techniques, with or without internal fixation or heterotopic bone grafting, have been described, but no single procedure has gained general acceptance. We present our results using a simple and reliable technique that employs a local bone graft and light internal fixation. From 1987 to 1996, eight consecutive patients with wrist lesions were treated using a modified Gill procedure for arthrodesis. The average age of patients was 62 years and the mean follow-up period was 4 years. A slab corticocancellous bone graft harvested from the dorsal aspect of the distal radius was turned about to cover the fusion mass from the distal radius to the third metacarpal bone. Kirschner wires and tension band wires were used to fix the wrist and compress the bone graft. A long arm cast was applied for 6 weeks, followed by a short arm cast until arthrodesis was achieved. The wrist position was well maintained by the tension band wire alone thereafter. Pain relief, grip strength, and assessment of daily activities were documented. Solid fusion was achieved smoothly in all cases and all patients were satisfied with the results. We recommend this simple and reliable technique for wrist arthrodesis.

Aged↗

PubMed1997

The effects of calcium phosphate particles on the growth of osteoblasts.

With advances in ceramics technology, calcium phosphate bioceramics have been applied as bone substitutes for several decades. The focus of this work is to elucidate the biocompatibility of the particulates of various calcium phosphate cytotoxicities. Four different kinds of calcium phosphate powders, including beta-tricalcium phosphate (beta-TCP), hydroxyapatite (HA), beta-dicalcium pyrophosphate (beta-DCP), and sintered beta-dicalcium pyrophosphate (SDCP), were tested by osteoblast cell culture. The results were analyzed by cell count, concentration of transforming growth factor-beta 1 (TGF-beta 1), alkaline phosphatase (ALP), and prostaglandin E2 (PGE2) in culture media. The changes were most significant when osteoblasts were cultured with beta-TCP and HA bioceramics. The changes in cell population of the beta-TCP and HA were quite low in the first 3 days, then increased gradually toward the seventh day. The changes in TGF-beta 1 concentration in culture medium inversely related to the changes in cell population. The ALP titer in the culture media of the beta-TCP and HA were quite high in the first 3 days, then decreased rapidly between the third and seventh days. The concentrations of PGE2 in the culture media tested were quite high on the first day, decreased rapidly to the third day, and then gradually until the seventh day. The changes in the beta-DCP and SDCP were quite similar to those of HA and beta-TCP but much less significant. We conclude that HA and beta-TCP have an inhibitory effect on the growth of osteoblasts. The inhibitins effects of the HA and beta-TCP powders on the osteoblast cell cultures possibly are mediated by the increased synthesis of PGE2.

Alkaline Phosphatase↗

PubMed1997

Extension of the range of DNA sequences available for triple helix formation: stabilization of mismatched triplexes by acridine-containing oligonucleotides.

Triple helix formation usually requires an oligopyrimidine*oligopurine sequence in the target DNA. A triple helix is destabilized when the oligopyrimidine*oligopurine target contains one (or two) purine*pyrimidine base pair inversion(s). Such an imperfect target sequence can be recognized by a third strand oligonucleotide containing an internally incorporated acridine intercalator facing the inverted purine*pyrimidine base pair(s). The loss of triplex stability due to the mismatch is partially overcome. The stability of triplexes formed at perfect and imperfect target sequences was investigated by UV thermal denaturation experiments. The stabilization provided by an internally incorporated acridine third strand oligonucleotide depends on the sequences flanking the inverted base pair. For triplexes containing a single mismatch the highest stabilization is observed for an acridine or a propanediol tethered to an acridine on its 3'-side facing an inverted A*T base pair and for a cytosine with an acridine incorporated to its 3'-side or a guanine with an acridine at its 5'-side facing an inverted G*C base pair. Fluorescence studies provided evidence that the acridine was intercalated into the triplex. The target sequences containing a double base pair inversion which form very unstable triplexes can still be recognized by oligonucleotides provided they contain an appropriately incorporated acridine facing the double mismatch sites. Selectivity for an A*T base pair inversion was observed with an oligonucleotide containing an acridine incorporated at the mismatched site when this site is flanked by two T*A*T base triplets. These results show that the range of DNA base sequences available for triplex formation can be extended by using oligonucleotide intercalator conjugates.

Acridines↗

PubMed1997

Induction of DNA topoisomerase II-mediated DNA cleavage by beta-lapachone and related naphthoquinones.

Recent studies have suggested that 3,4-dihydro-2,2-dimethyl-2H-naphtho[1,2-b]pyran-5,6-dione (beta-lapachone) inhibits DNA topoisomerase I by a mechanism distinct from that of camptothecin. To study the mechanism of action of beta-lapachone, a series of beta-lapachone and related naphthoquinones were synthesized, and their activity against drug-sensitive and -resistant cell lines and purified human DNA topoisomerases as evaluated. Consistent with the previous report, beta-lapachone does not induce topoisomerase I-mediated DNA breaks. However, beta-lapachone and related naphthoquinones, like menadione, induce protein-linked DNA breaks in the presence of purified human DNA topoisomerase IIalpha. Poisoning of topoisomerase IIalpha by beta-lapachone and related naphthoquinones is independent of ATP and involves the formation of reversible cleavable complexes. The structural similarity between menadione, a para-quinone, and beta-lapachone, an ortho-quinone, together with their similar activity in poisoning topoisomerase IIalpha, suggests a common mechanism of action involving chemical reactivity of these quinones. Indeed, both quinones form adducts with mercaptoethanol, and beta-lapachone is 10-fold more reactive. There is an apparent correlation between the rates of the adduct formation with thiols and of the topoisomerase II-poisoning activity of the aforementioned quinones. In preliminary studies, beta-lapachone and related naphthoquinones are found to be cytotoxic against a panel of drug-sensitive and drug-resistant tumor cell lines, including MDR1-overexpressing cell lines, camptothecin-resistant cell lines, and the atypical multidrug-resistant CEM/V-1 cell line.

Antineoplastic Agents, Alkylating↗

PubMed1997

In vitro cell behavior of osteoblasts on Pyrost bone substitute.

BACKGROUND: Pyrost bone substitute has been shown to be a promising orthopedic biomaterial. However, little is known about mechanisms that are responsible for the genesis and development of the bond between bone and the Pyrost bone substitute. The purpose of this study is to elucidate the in vitro cell behavior of osteoblasts on Pyrost bone substitute. METHODS: By using primary culture of rat osteoblasts, the changes in cell morphology during adhesion and flattening onto the surface of Pyrost bone substitute were studied in vitro. At 1 hour, at 3 hours, and at days 1, 3, and 7 after layering, the cell behavior was observed with scanning electron microscope. RESULTS: The processes of trypsinized osteoblast adhesion and spreading on Pyrost bone substitute consisted of 1) contact of rounded osteoblasts with the Pyrost substrate; 2) attachment of osteoblasts at point of contact; 3) centrifugal growth of filopodia; 4) flattening and spreading of the osteoblasts on the Pyrost substrate; 5) division and growth of osteoblasts; and 6) suspension of the osteoblasts across the pores by their processes. CONCLUSIONS: These results demonstrated that Pyrost can form a physico-chemical bond with osteoblasts. The Pyrost bone substitute not only supports osteoblasts attachment but also allows proliferation of the osteoblasts.

Animals↗

PubMed1997

Effects of calcium phosphate bioceramics on skeletal muscle cells.

With advances in ceramics technology, calcium phosphate bioceramics have been applied as bone substitutes. The effects of implants on bony tissue have been investigated. The effects upon adjacent skeletal muscles have not been determined. The focus of this work is to elucidate the biological effects of various calcium phosphate bioceramics on skeletal muscles. Four different kinds of powder of calcium phosphate biomaterials including beta-tricalcium phosphate (beta-TCP), hydroxyapatite (HA), beta-dicalcium pyrophosphate (beta-DCP) and sintered beta-dicalcium pyrophosphate (SDCP), were tested by myoblast cell cultures. The results were analyzed by cell count, cell morphology and concentration of transforming growth factor beta 1 (TGF-beta 1) in culture medium. The cell population and TGF-beta 1 concentration of the control sample increased persistently as the time of culture increased. The changes in cell population and TGF-beta 1 concentration in culture medium of the beta-TCP and HA were quite low in the first 3 days of culture, then increased gradually toward the seventh day. The changes in cell population and TGF-beta 1 concentration in culture medium of the silica, beta-DCP, and SDCP were quite similar. They were lower during the first day of culture but increased and reached that of the control medium after 7 days' culture. Most cells on B-TCP and HA diminished in size with radially spread, long pseudopods. We conclude that HA and beta-TCP are thought to have an inhibitory effect on growth of the myoblasts. The HA and beta-TCP may interfere with the repair and regeneration of injured skeletal muscle after orthopedic surgery.

Animals↗

PubMed1997

Menadione-induced cytotoxicity to rat osteoblasts.

Oxygen-derived free radical injury has been associated with several cytopathic conditions. Oxygen radicals produced by chondrocytes is an important mechanism by which chondrocytes induce matrix degradation. In the present study, we extend these observations by studying oxidative processes against osteoblasts. Osteoblasts were mixed in in vitro culture with 200 microM menadione. The cytotoxic effect of menadione-induced oxidative stress was monitored by lucigenin- or luminol-amplified chemiluminescence, tetrazolium assay and immunocytochemical study. Results showed that adding menadione induces an oxidative stress on osteoblasts, via superoxide and hydrogen peroxide production, that can be eradicated by superoxide dismutase (SOD) and catalase in a dose-dependent manner. Catalase and the appropriate concentration of dimethyl sulfoxide have a protective effect on cytotoxicity induced by menadione, whereas SOD does not. Menadione-treated osteoblasts have a strong affinity for annexin V, and the nuclei are strongly stained by TUNEL (TdT-mediated dUTP nick-end labelling). The results suggest that menadione-triggered production of reactive oxygen species leads to apoptosis of osteoblasts.

Acridines↗

PubMed1997

Effect of hydroxyapatite particle size on myoblasts and fibroblasts.

After surgery, the bone and soft tissues around integrated biomaterials can be adversely affected by implant-related factors acting over a period of years. However, few studies have directly addressed the effects upon the adjacent soft tissue. The present study was designed to test the biological effects of various sized hydroxyapatite (HA) particles on myoblasts and fibroblasts. Both the myoblasts and fibroblasts were mixed in in vitro culture with 0.1% (1 mg ml(-1)) of various sized HA particles (0.5-3.0, 37-63, 177-250, 420-841 microm) for 1 h, 3 h, 1 day, 3 days and 7 days to test their effects on the cell culture. The results show that adding HA particles into a cell culture can decrease the cell count significantly. The transforming growth factor-beta1 (TGF-beta1) concentrations in the culture medium decreased significantly on addition of HA particles. When calculated as a ratio to the cell number, the TGF-beta1 titre increased most significantly in the groups of medium-sized particles. The prostaglandin E2 (PGE2) concentrations in the medium increased significantly. The changes in TGF-beta1 and PGE2 concentrations with the smallest particles were most significant and persisted longer. The inhibitory effects of the HA particles on the cell culture were mediated by the increased synthesis of PGE2. Caution should be exercised before considering the use of an HA product which could easily break down into a fine powder.

Animals↗