Biomedical subjects

V Salih

Publications and source records attributed to V Salih.

At least 19 recordsLinked to original sources

PubMed2006

Photodynamic therapy down-regulates the invasion promoting factors in human oral cancer.

Squamous cell carcinomas of the head and neck are characterized by their high tendency for invasion and metastasis. Several studies have identified the roles of matrix metalloproteinases (MMPs), vascular endothelial growth factors (VEGF) and urokinase plasminogen activators (uPA) in this process. Photodynamic Therapy (PDT) is an emerging treatment currently in clinical practice for the treatment of early cancer. Here we evaluate, in vitro, the influence of PDT on the expression of these molecules. A series of human keratinocyte cell lines derived from human oral squamous cell carcinomas (OSCC) were used as the PDT 'targets' in this study. Each cell line was subjected to sublethal dose of PDT. Activity of MMP-2, MMP-9, MMP-13, uPA and VEGF were evaluated at protein levels using zymography and ELISA on culture medium. For uPA, a chromogenic assay was performed. Gelatin zymography results revealed that, in control medium, MMP-9 and MMP-2 were secreted in proform. MMP-2 was highly expressed by H376 cells while VB6 and UP cells relatively show similar MMP-2 with comparatively low expression. For MMP-9, the latent type was highly expressed by VB6 cells and only slightly by H376, while active-MMP-9 was expressed by VB6 cell line only. Following PDT, both active and latent MMP-2 and MMP-9 were down regulated by UP and VB6 cells (p<0.001), while H376 showed an increase in active-MMP-2. These observations were supported by ELISA. This study has demonstrated that, PDT causes the suppression of factors responsible for tumour invasion which may be of therapeutic value.

Antineoplastic Agents↗

PubMed2006

Shedding of a soluble form of BMP receptor-IB controls bone cell responses to BMP.

Bone morphogenetic proteins (BMP) are members of the transforming growth factor beta (TGF-beta) superfamily and are involved in a wide variety of biological processes, including osteoblast differentiation and bone healing. The activities of the BMP are mediated by signal transduction via three BMP receptors (BMPR-IA, -IB and -II), which are thus essential for the biological actions of the BMP. Although the precise mechanisms which control the BMPR are not yet known, it is possible that post-translational regulation of these cell surface antigens by shedding could modulate their expression and thereby at least partly determine the response of the cells to the BMP. To test this possibility, the present study has examined whether soluble forms of the BMPR are produced by shedding from primary human bone cells in vitro. The results showed that human bone cells expressed both mRNA transcripts and antigens corresponding to BMPR-IA, -IB and -II. Incubation of the cells with phorbol 12-myristate 13-acetate (PMA), a potent inducer of proteolytic shedding, resulted in a pronounced decrease in cell surface expression of all three BMPR and, concurrently, the presence of "soluble" forms of these antigens in culture supernatants. Moreover, PMA treatment significantly reduced the level of BMP-2-induced Smad1/5 phosphorylation, a major early activation step in signal transduction initiated by BMP/BMPR interaction. It is notable that, while treatment of bone cells with interleukin-1beta (IL-1beta) also reduced the level of surface BMPR-IB, this inflammatory cytokine had no effect on BMPR-IA or -II levels, hence only the soluble form of BMPR-IB was detected. Furthermore, in addition to down-regulating BMP-2-induced Smad1/5 phosphorylation, IL-1beta also caused a reduction in the level of BMP-2-induced alkaline phosphatase activity and osteocalcin expression, both closely associated with bone cell differentiation. In conclusion, our study has provided evidence, for the first time, that BMPR can be modulated at the cell surface by the shedding of a soluble form of the antigen, resulting in a markedly diminished response to BMP-2 in vitro.

Blotting, Western↗

PubMed2006

Bone morphogenetic protein receptors and bone morphogenetic protein signaling are controlled by tumor necrosis factor-alpha in human bone cells.

Bone morphogenetic proteins (BMP) stimulate osteoblast differentiation by signal transduction via three BMP receptors (BMPR-IA, -IB and -II), whereas the inflammatory cytokine tumor necrosis factor-alpha (TNF-alpha) has been shown to suppress osteoblast differentiation. Although the mechanisms which regulate the BMPR are not yet known, it is possible that they may be negatively controlled by TNF-alpha, thereby inhibiting BMP-induced osteoblast differentiation. To test this hypothesis, we have examined the effects of TNF-alpha on BMPR-IA, -IB and -II expression and the functional consequences of this cytokine on BMPR-mediated functions in human bone cells. The results showed that although TNF-alpha down-regulated BMPR-IA and -II transcripts, it increased the level of BMPR-IB mRNA via a MAPK-dependent pathway. In marked contrast, however, TNF-alpha nevertheless caused marked down-regulation of the expression of the BMPR-IB surface antigen specifically. Moreover, the cytokine-induced decrease in BMPR-IB expression was found to be associated with the concurrent presence of a 'soluble' form of this antigen in supernatants of TNF-alpha-treated cultures. Furthermore, the TNF-alpha-induced loss of BMPR-IB was found to ablate BMP-2-stimulated bone cell functions, including phosphorylation of Smad1/5/8, alkaline phosphatase activity and osteocalcin expression. In conclusion, our study has provided evidence, for the first time, that BMPR can be differentially modulated by TNF-alpha at both the post-transcriptional and post-translational levels, with the TNF-alpha-induced shedding of the BMPR-IB antigen associated with a significantly diminished response to BMP-2 in vitro.

Antigens↗

PubMed2006

Fluorescence spectroscopy combined with 5-aminolevulinic acid-induced protoporphyrin IX fluorescence in detecting oral premalignancy.

BACKGROUND: Early detection of premalignant/malignant lesions in the oral cavity can certainly improve the patient's prognosis. This study presents fluorescence imaging with the topical application of 5-aminolevulinic as a way to improve detection of various oral tissue pathologies. This procedure depends mainly on comparing the intensity of red and green fluorescence emitted from tissues during examination. MATERIALS AND METHODS: Seventy-one patients who presented with clinically suspicious oral leukoplakia were recruited for this study. Each of the patients was required to have 5-aminolevulinic acid in the form of mouth rinse prior to fluorescence imaging. Following this a surgical biopsy was acquired from the exact examination site. The results of the fluorescence spectroscopy have been compared with histopathology. RESULTS: A Student's t-test was applied to test the viability of the ratio between red and green fluorescence. The red-to-green ratio was found to increase significantly when the lesion was identified as dysplastic or carcinoma in situ. By applying a threshold line to discriminate between normal and dysplastic lesions; a sensitivity of 83-90% and specificity of 79-89% were obtained. CONCLUSION: Fluorescence spectroscopy combined with 5-aminolevulinic acid-induced protoporphyrin IX was found as a valuable tool in the diagnosis of oral premalignancy. This technique offers the potential to be advantageous over other non-optical techniques in terms of providing real-time diagnosis, in situ monitoring, cost effectiveness and more tolerated by patient compared to surgical biopsy.

Adult↗

PubMed2006

Assessment of oral premalignancy using elastic scattering spectroscopy.

Optical spectroscopy systems have been involved in various clinical fields; however the main interest is still in the diagnosis of premalignant/malignant lesions. The aim of this study was to compare findings of Elastic Scattering Spectroscopy (ESS) with histopathology of oral tissues to see if this technique could be used as an adjunct or alternative to histopathology in identifying dysplasia. The technique involves the use of Mie scattering and is a simple non-invasive method of tissue interrogation. Twenty-five oral sites from 25 patients who presented with oral leukoplakia were examined by ESS using a pulsed xenon-arc lamp. Surgical biopsies were acquired from each of the examination sites. The results of the acquired spectra were then compared with histopathology. Two sets of spectra were obtained, and by using a linear discriminant analysis, a sensitivity of 72% and a specificity of 75% were obtained. These results are promising and could suggest that ESS may be able to identify dysplasia in oral tissues. To prove the usefulness of the ESS in dysplasia detection in oral tissues conclusively, a larger body of data is needed. We aim to continue this study to obtain more data in an attempt to increase the accuracy of the technique. Large, multi-centre trails are needed for each anatomical site, in order to gather more information about the differences between normal and dysplastic tissue.

Adult↗

PubMed2005

Effects of ultrasound on transforming growth factor-beta genes in bone cells.

Therapeutic ultrasound (US) is a widely used form of biophysical stimulation that is increasingly applied to promote fracture healing. Transforming growth factor-beta (TGF-beta), which is encoded by three related but different genes, is known to play a major part in bone growth and repair. However, the effects of US on the expression of the TGF-beta genes and the physical acoustic mechanisms involved in initiating changes in gene expression in vitro, are not yet known. The present study demonstrates that US had a differential effect on these TGF-beta isoforms in a human osteoblast cell line, with the highest dose eliciting the most pronounced up-regulation of both TGF-beta1 and TGF-beta3 at 1 hour after treatment and thereafter declining. In contrast, US had no effect on TGF-beta2 expression. Fluid streaming rather than thermal effects or cavitation was found to be the most likely explanation for the gene responses observed in vitro.

Acoustics↗

PubMed2005

Soluble phosphate glass fibres for repair of bone-ligament interface.

Phosphate-based fibres of the generic composition (CaO)0.46-(Na2O)n-(Fe2O3)y-(P2O5)0.50 have been evaluated, in vitro, as three dimensional scaffolds for tissue engineering of the hard-soft tissue interface by assessing the fibre solubility and growth and functional gene expression of human cells. Primary human osteoblasts and fibroblasts were seeded onto scaffolds and maintained in culture for up to 21 days. Fluorescent immunolabeling revealed the spread cell morphology and significant proliferation pattern on these fibres, particularly on the 3 mol% Fe2O3-containing formulation. Real-time quantitative Polymerase Chain Reaction (rtQ-PCR) analysis of gene expression using TaqMan Probes was preformed and it has been established that committed cell differentiation was maintained by both cell types, and was strongly related to the 3 mol% Fe2O3 glass composition. These novel, readily manufactured, soluble glass fibres offer a biocompatible and biochemically favourable alternative in the search for suitable degradable materials used in Tissue Engineering.

Bone and Bones↗

PubMed2004

Gene expression profiling of bone cells on smooth and rough titanium surfaces.

Titanium (Ti) and Ti alloys are widely used as dental and orthopaedic implants, but the effects of the surface characteristics of these materials on the response of cells and target tissues is not well understood. The present study has therefore examined the effects of a rough Ti (RT) and a smooth Ti (ST) surface on human bone cells in vitro. Scanning electron microscopy showed attachment and spreading of cells on both surfaces. Expression profiling using ATLAS gene arrays showed marked differences in gene responses after 3 h of culture. A number of osteoblast genes were identified as "roughness response" genes on the basis of changes in expression on the RT compared with the ST surfaces. The surface roughness of Ti was thus found to have a profound effect on the profile of genes expressed by the bone cells, and suggests that improvements in the biological activity and possibly the clinical efficacy of these materials could be achieved by selective regulation of gene expression mediated by controlled modification of Ti surface.

Adult↗

PubMed2004

Roughness response genes in osteoblasts.

Titanium (Ti) and Ti alloys are widely used as dental and orthopedic implants, but the effects of the surface characteristics of these materials, including roughness, on the response of target tissues in vivo are not well understood. The present study has therefore examined the effects of a moderately rough (sand-blasted, acid-etched; SLA) Ti surface, a highly rough (plasma-sprayed; TPS) surface, and a smooth surface (SMO) on bone cells in vitro. X-ray photoelectron spectroscopy showed that these surfaces had similar surface chemistry, while scanning electron microscopy suggested that the SLA provided a transiently less biocompatible surface, with initially less well-attached cells. SLA also delayed bone cell growth compared with SMO, whereas the TPS surface elicited the greatest increase in cell numbers. In addition, expression profiling using the ATLAS gene array showed marked differences in gene responses after 3 h of incubation; this increased further after 24 h, with TPS generating the largest number of up- and down-regulated genes compared with SLA and SMO. A number of osteoblast genes were also identified as 'roughness' genes on the basis of their similar response on SLA and TPS, compared with SMO. These findings show, for the first time, that the surface roughness of Ti has a profound effect on the profile of genes expressed by bone cells and suggest that improvements in the biological activity and possibly the clinical efficacy of these materials could be achieved by selective regulation of gene expression mediated via modification of surface roughness.

Adult↗

PubMed2002

The effect of MgO on the solubility behavior and cell proliferation in a quaternary soluble phosphate based glass system.

This paper presents a systematic study of the MgO-CaO-Na(2)O-P(2)O(5) glass system, which has great potential to be used as temporary hard and soft tissue implant materials. An overall study of solubility behavior of ternary and quaternary-based phosphate glass system have been carried out in order to understand the out-leaching progress of different ions and to determine their effect on cell proliferation. Originally, soluble phosphate based glasses within the ternary glass system of Na(2)O-CaO-P(2)O(5) have been developed to create a simple baseline system. This paper, however, presents the development of this system by introducing magnesium oxide as a partial calcium oxide substitute and solubility behaviors as well as cell studies have been carried out to check the effect on magnesium ions. Glasses have been prepared via standard glass melting techniques and their solubility behavior has been tested in distilled water via simple weight loss, pH and ion measurements. The way the glasses dissolve is an inverse exponential behavior which is mirrored by the calcium ion release. Other ions show a less exponential behavior. The MTT test has been used to check preliminary in vitro studies on a human MG63 cell line and the result indicates that cell proliferation is increased for glasses with minimal CaO substitution.

Journal Article↗

PubMed2001

Retroviral transduction of alveolar bone cells with a temperature-sensitive SV40 large T antigen.

We have transduced adult human alveolar bone (AB) cells with a gene construct encoding a temperature-sensitive mutation of the SV40 large T antigen (tsT). Such cells divided rapidly, for more than 50 passages thus far, at a permissive low temperature (34.5 degrees C), comparable to the non-transduced parental cells at 37 degrees C. However, the tsT-transduced AB cells failed to grow at a non-permissive high temperature (39 degrees C) at which the T antigen is inactivated. Nevertheless, the cells formed mineralised nodules in vitro at both the low and high temperatures. Flow cytometry analysis showed that the transduced cells cultured at 34.5 degrees C, like the parental cells at 37 degrees C, were smaller and less granular than the transduced cells incubated at 39 degrees C. Moreover, the transduced cells grown at 34.5 degrees C were also found to express bone sialoprotein, osteopontin and type I collagen at levels similar to those of the parental cells at 37 degrees C, although osteonectin and fibronectin were down-regulated. When the transduced cells were incubated at 39 degrees C, the expression of all antigens was up-regulated, particularly osteonectin. Thus, we have obtained long-term cultures of tsT-transduced AB cells whose growth is temperature-dependent and which express certain features characteristic of bone-derived cells.

Antigens, Polyomavirus Transforming↗

PubMed2001

Glass reinforced hydroxyapatite for hard tissue surgery--part II: in vitro evaluation of bone cell growth and function.

Hydroxyapatite (HA)-based materials are considered to be potentially useful as bone implant materials, particularly those reinforced with glass to improve mechanical strength. However, the precise effects of glass-reinforced HA on the growth and functions of bone cells are still unclear. The present study has therefore examined the response of human osteoblast-like cells to HA and HA reinforced with two different proportions of glass, namely 2.5% and 5%. All materials enabled the cells to attach and proliferate during 7 days in culture and, although the growth was less than on control plastic surfaces, there was no deleterious effect of the 5% glass composite compared with HA alone. Flow cytometry analysis showed that there was no effect on cell size and granularity, but there were marked and highly selective changes in the expression of certain connective tissue proteins. Thus, while bone sialoprotein and osteonectin were down-regulated on HA alone, the expression of these antigens was relatively enhanced on the composite materials, and collagen type I was also up-regulated on the glass-reinforced HA. Thus, modulation of the glass composition of HA materials could be used to produce not only improved mechanical strength, but also enhanced biocompatibility.

Biocompatible Materials↗

PubMed2001

Effects of ultrasound on the growth and function of bone and periodontal ligament cells in vitro.

The effects of therapeutic ultrasound (US) on tissue healing processes in vivo are likely to involve US-induced changes in key cellular functions. However, these have not yet been clearly delineated and the present study has, therefore, examined the effects of a single 5-min CW exposure of 3.00-MHz US on the growth and functional activity of a human osteoblast-like cell line (MG63 cells) and human periodontal ligament (PDL) cells in vitro. Although cell proliferation was found to be largely unaffected by spatial average intensity (I(SA)) values of between 140-990 mW/cm(2), flow cytometry (FCM) analysis showed that there were pronounced and differential effects on cell function. Thus, bone-associated proteins were down-regulated, whereas collagen type I (COL I) was unaffected and fibronectin (FN) was up-regulated at low intensities in MG63 cells. In contrast, bone protein expression was found to be dose-dependent, and FN and COL I were down-regulated in PDL cells. These results show that US has potentially important effects on the functional activities of connective tissue cells in vitro, which could markedly influence tissue repair and regeneration processes in vivo.

Cell Division↗

PubMed2000

Development of soluble glasses for biomedical use Part II: the biological response of human osteoblast cell lines to phosphate-based soluble glasses.

Soluble glasses are considered to be of potential clinical value in orthopaedic and dental surgery. However, the biological response to these materials is not well understood. To determine the effects of these glasses, two human osteoblast cell lines, MG63 and HOS (TE85), were incubated in vitro in the presence of increasing concentrations of extracts of the glasses. The effects of the extracts on cell growth was measured using the MTT assay and an ELISA assay was used to measure the expression of bone sialoprotein (BSP), osteonectin (ON) and fibronectin (FN), antigens which play a fundamental part in the integrity and function of hard connective tissue. The results showed that the proliferation of the cells was adversely affected only by the more soluble glasses, which also down-regulated the expression of the bone-associated proteins. In contrast, the extract of the glass with the lowest dissolution rate, which contains relatively elevated levels of Ca2+, was found to enhance bone cell growth and antigen expression. These findings suggest that the compositions of these glasses at least partly determine the response of cells and thus, that the glasses could be modified to elicit a more optimal biological response and clinical efficacy.

Journal Article↗

PubMed1997

Effect of normal synovial fluid on the metabolism of articular chondrocytes in vitro.

It is thought that articular cartilage gains most of its nutrition in vivo, via diffusion, from synovial fluid. There have been few studies investigating the effect of synovial fluid on chondrocyte metabolism in vitro. In the current study, bovine articular chondrocytes were isolated and cultured in agarose using normal allogenic synovial fluid as culture medium. Dulbecco's minimal essential medium + 20% fetal calf serum and Earle's balanced salt solution were used as control media. Cell viability at the end of the experiment showed that neither synovial fluid nor Earle's balanced salt solution had a significant effect on viability when compared with Dulbecco's minimal essential medium + 20% fetal calf serum during the period assessed. Results indicate that levels of glycosaminoglycan synthesis can be maintained when Dulbecco's minimal essential medium + 20% fetal calf serum is diluted with Earle's balanced salt solution to levels of 80% Earle's balanced salt solution. When Dulbecco's minimal essential medium + 20% fetal calf serum was diluted with synovial fluid, glycosaminoglycan synthesis was stimulated in a dose dependent manner to 80% synovial fluid. Even at 100% synovial fluid, synthesis levels were significantly higher than for Dulbecco's minimal essential medium + 20% fetal calf serum. Tritiated thymidine uptake decreased with increasing concentrations of either Earle's balanced salt solution or synovial fluid. The results suggest that culture in synovial fluid induces a state similar to that seen in vivo, with high levels of glycosaminoglycan synthesis and low levels of cell division.

Animals↗

PubMed1993

Effect of vascular clamp on endothelial integrity of the internal mammary artery.

The preservation of endothelial integrity is essential for maintaining patency of vascular grafts. The internal mammary artery flow is often interrupted with the application of a soft vascular clamp to achieve a bloodless field during the anastomosis. We investigated the effect of the vascular clamp on the internal mammary artery endothelium using the scanning electron and light microscope. The endothelium was examined before and at 15 and 30 minutes after clamping in both the pedicled and the skeletonized arteries. Endothelial integrity was breached by clamping with early evidence of platelet adhesion to the damaged areas. The severity of the endothelial damage was related to the clamp time, but there was no difference in the degree of damage between the pedicled and the skeletonized arteries. We conclude that the vascular clamp causes injury to the internal mammary artery endothelium and may be implicated in early postoperative graft failure.

Constriction↗

PubMed1993

Myofibroblasts in hollow visceral myopathy: the origin of gastrointestinal fibrosis?

A patient with hollow visceral myopathy is reported in whom light microscopical studies of the small and large intestine showed typical features of degeneration, thinning, and fibrous replacement of smooth muscle of the gastrointestinal tract. Electron microscopy showed a striking increase in collagen with minimal fibroblast proliferation. Smooth muscle fibres had a range of ultrastructural abnormalities including myofilament disarray, electron lucency of the cytoplasm, and proliferation of the endoplasmic reticulum. Some fibres seemed to have typical ultrastructural characteristics of myofibroblasts, and others to be transition forms between typical smooth muscle cells and typical myofibroblasts. It seems likely that the fibrosis typical of this disorder has its origin in the transformation of smooth muscle fibres from a purely contractile to a myofibroblast collagen synthetic phenotype.

Adolescent↗

PubMed1993

Pathological sequelae of implantation of intracorporeal left ventricular assist devices in the calf.

Thromboembolic complications have previously been a major pathological complication of left ventricular assist device (LVAD) insertion and appear to be a consequence of the use of smooth polyurethane linings. Textured biomaterial surfaces are designed to attract a stable coagulum which becomes organized to form a neointima. We describe the pathological changes following experimental implantation of textured-surface LVADs in calves. The incidence of systemic embolization from such linings appears to be low. Surface modifications with cell seeding offer the possibility of further reduction in incidence of this problem. However, degradation of prosthetic valves may be a potential source of emboli and infection. With these complications minimized, the most significant pathological changes observed appear to relate to the device haemodynamics. At present renovascular changes associated with systemic hypertension appear to be the greatest potential problem for the long-term use of these devices.

Animals↗