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Microsc Res Tech. 2000 Oct 15;51(2):191-203.
Matrix-specific FAK and MAPK reorganization during Caco-2 cell motility.
Yu CF, Basson MD.
Departments of Surgery, Yale University School of Medicine and CT VA Health Care System, New Haven, Connecticut 06511, USA.
We have previously reported that Caco-2 cell motility redistributes FAK, paxillin, and activates p38. However, the subcellular organization of these intracellular signals during cell migration is unclear. We, therefore, investigated the organization of actin, FAK, paxillin, and activated ERK and activated p38 during Caco-2 motility across collagen I, fibronectin, laminin, and tissue culture treated glass. Differential density seeding generated homogeneous static and migrating populations. Expression of actin, FAK, paxillin, phospho-ERK, and phospho-p38 were examined by immunofluorescent staining in static and motile cells. Actin was concentrated toward the peri-nuclear central area of cells migrating on matrix proteins studied. Actin immunoreactivity was decreased in the leading edge of lamellipodia. FAK immunoreactivity was weaker in migrating cells than in static cells on the same matrix. FAK was expressed along cell-cell contacts of both cell populations, but absent in migrating lamellipodia of matrix-cultured cells. Paxillin staining was diffuse in static cells but organized toward migrating lamellipodia in a radial manner. Like FAK, phosphorylated ERK was expressed in the central region of migrating cells but was dramatically decreased at areas of cell-cell contact and free lamellipodia. Fibronectin exerted the greatest effect on ERK activation in all matrix proteins studied. In contrast, phosphorylated p38 staining was stronger in migrating cells on matrix than in static cells on the same matrix. Phosphorylated p38 was expressed in the nuclear of migrating cells and disappeared in the cell-cell contact side and free lamellipodia. Interestingly, the reorganization of these proteins was distinctly different on tissue culture treated glass without a physiologic matrix substrate. For instance, FAK staining increased rather than decreased in motile cells on plastic, and lamellipodial FAK staining could be discerned. Matrix may influence Caco-2 biology during migration not only by triggering intracellular phosphorylation events but also by reorganizing the cytoskeleton and the subcellular localization of these intracellular signals. 2000 Wiley-Liss, Inc.
online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11054869&dopt=Abstract
Biomaterials. 2000 Dec;21(23):2427-31.
Extracellular matrix protein gene expression of bovine chondrocytes cultured on resorbable scaffolds.
Saldanha V, Grande DA.
Department of Surgeon, Division of Orthopaedics, North Shore University Hospital, Manhasset, NY 11030, USA.
It has been demonstrated that using cultured chondrocytes that have been seeded onto various biomatrices can enhance the quality of the articular cartilage repair tissue. As tissue-engineering becomes increasingly more complex there is a need to understand how a specific biomaterial may influence gene expression. In this study several commonly used scaffold materials for cartilage tissue engineering were evaluated with respect to their influence on matrix gene expression. Primary cultures of bovine chondrocytes were established in monolayer then seeded onto polylactic acid (PLLA), polyglycolic acid (PGA), collagen matrices. The induction of collagen type I, collagen type II, and aggrecan was observed at various time points on these biomaterials using RT-PCR. The collagen type I gene was upregulated on collagen scaffolds throughout the culture period. PLLA and PGA showed initial induction followed by downregulation. Monolayer culture did not induce collagen I message. Collagen II genes were selectively upregulated after 72 and 96 h post seeding depending the scaffold material. Monolayer culture had strong induction of collagen II. The aggrecan protein was consistently expressed in all scaffold materials cultures and monolayer.
online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11055290&dopt=Abstract
Biomaterials. 2000 Dec;21(23):2461-74.
Analysis of retrieved polymer fiber based replacements for the ACL.
Guidoin MF, Marois Y, Bejui J, Poddevin N, King MW, Guidoin R.
Department of Surgery, Laval University, Quebec, QC, Canada.
The present retrospective analysis of 117 surgically excised anterior cruciate ligament (ACL) prostheses was designed to elucidate the etiology and mechanisms of failure of synthetic ligamentous prostheses. They were harvested from young and active patients (26 +/- 7 yrs) at various orthopaedic centers in France between 1983 and 1993. The average duration of implantation of augmentation and replacement prostheses were 21.5 +/- 12.6 and 33.2 +/- 25.3 months, respectively. The principal causes for their excision were ruptures and synovitis. Each ACL prosthesis was examined macroscopically, histologically, and, after tissue removal, by scanning electron microscopy (SEM) to determine the model, manufacturer, surgical technique used at implantation, the extent of healing, the site of rupture, and the morphology of the damaged fibers. Fourteen types of ACL prostheses were analysed, each fabricated using a different combination of polymers, fibers and textile constructions. Consequently, they generated a variety of healing characteristics and mechanical responses in vivo. SEM observations revealed that abrasion of the textile fibers as a result of yarn-on-yarn and/or yarn-on-bone contact was a common phenomenon to almost all models, and was the primary cause of prosthetic failure. Healing inside the synthetic ACL was poorly organized, incomplete and unpredictable as the extent of collagenous infiltration into the textile structure did not increase with the duration of implantation. In fact, the collagenous infiltration into certain models appeared to be more detrimental than beneficial since it caused deterioration and fraying of the textile structure rather than serving as a reinforcing matrix around the prosthesis. In conclusion, the present study shows that three mechanisms may be involved in the failure of ACL prostheses: (1) inadequate fiber abrasion resistance against osseous surfaces; (2) flexural and rotational fatigue of the fibers, and (3) loss of integrity of the textile structure due to unpredictable tissue infiltration during healing.
online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11055294&dopt=Abstract
Clin Chem Lab Med. 2002 Sep;40(9):941-5.
Infrequent somatic deletion of the 5' region of the COL1A2 gene in oesophageal squamous cell cancer patients.
Dietzsch E, Parker MI.
Division of Medical Biochemistry, Faculty of Health Sciences, University of Cape Town, South Africa.
Oesophageal squamous cell cancer is the leading cause of cancer death amongst African males in South Africa. DNA was isolated from normal and tumour biopsies of the oesophagi of 33 African patients with squamous cell carcinoma of the oesophagus and was analysed with two dinucleotide repeat polymorphisms, a GT repeat sequence in the first intron, and a CA repeat in the promoter of the human alpha2(I) procollagen gene (COL1A2), using the polymerase chain reaction (PCR). Normal and tumour DNAs from each individual were compared to identify changes present in the tumour DNA, but absent in normal DNA. Twenty two cases were informative (heterozygous) for the promoter polymorphism and 24 cases were informative for the intronic polymorphism. Loss of heterozygosity (LOH) was seen in 2/22 (9.1%) for the promoter and 3/24 (12.5%) for the intronic polymorphism. These changes involved a total of three patients: two patients displayed the lost allele incorporating both the CA repeat and GT repeat loci; the third patient revealed LOH at the intronic polymorphism, but was non-informative (homozygous) for the promoter polymorphism. Deletions within the procollagen genes may represent an as yet unrecognised but rare event in the multistep process of carcinogenesis.
online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12435113&dopt=Abstract
Blood Press. 2000;9(4):227-38.
Testosterone increases blood pressure and cardiovascular and renal pathology in spontaneously hypertensive rats.
Seachrist D, Dunphy G, Daneshvar H, Caplea A, Milsted A, Ely D.
Department of Biology, The University of Akron, Ohio 44325-3908, USA.
The objective of this paper was to test the hypothesis that testosterone (T) raises blood pressure (BP), which is associated with increased coronary adventitial collagen, whereas the hemodynamic force of BP increases the coronary media:lumen ratio. Five treatment groups of spontaneously hypertensive rat (SHR) were established (n = 8-10 per group): controls; hydralazine (HYZ); castration; castration + HYZ; and castration + HYZ + T + captopril. At 12 weeks of age, the castrate + HYZ group was divided so that the mean BP was the same in both groups (162 mmHg). Both groups continued to receive HYZ treatment; however one group received T implants. Also, at 12 weeks of age the castrate + HYZ + T + captopril group received T implants. BP in the HYZ group was reduced compared with controls (192 mmHg vs 218 mmHg, p < 0.01). Castration lowered BP to 170 mmHg (p < 0.01) compared with controls. However, T implants increased BP by 15 mmHg (p < 0.02) in the castrate + HYZ group and by 44 mmHg in the castrate + HYZ + captopril group (p < 0.01). Captopril in combination with HYZ significantly reduced BP compared with controls but T replacement increased BP and coronary collagen deposition in spite of HYZ and captopril treatment.
online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11055476&dopt=Abstract
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