Biomedical subjects

Jerome A Werkmeister

Publications and source records attributed to Jerome A Werkmeister.

9 recordsLinked to original sources

PubMed2006

MR three-dimensional molecular imaging of intramural biomarkers with targeted nanoparticles.

In this study, porcine carotid arteries were subjected to balloon overstretch injury followed by local delivery of paramagnetic nanoparticles targeted to alphavbeta3-integrin expressed by smooth muscle cells or collagen III within the extracellular matrix. Carotid T1-weighted angiography and vascular imaging was performed at 1.5T. While MR angiograms were indistinguishable between control and targeted vessel segments, alphavbeta3-integrin-and collagen Ill-targeted nanoparticles spatially delineated patterns and volumes of stretch injury. In conclusion, MR molecular imaging with alphavbeta3-integrin or collagen Ill-targeted nanoparticles enables the non-invasive, three-dimensional characterization of arterial pathology unanticipated from routine angiography.

Animals↗

PubMed2005

Repair of porcine articular cartilage defect with autologous chondrocyte transplantation.

Articular cartilage is known to have poor healing capacity after injury. Autologous chondral grafting remains the mainstay to treat well-defined, full-thickness, symptomatic cartilage defects. We demonstrated the utilization of gelatin microbeads to deliver autologous chondrocytes for in vivo cartilage generation. Chondrocytes were harvested from the left forelimbs of 12 Lee-Sung pigs. The cells were expanded in monolayer culture and then seeded onto gelatin microbeads or left in monolayer. Shortly before implantation, the cell-laden beads were mixed with collagen type I gel, while the cells in monolayer culture were collected and re-suspended in culture medium. Full-thickness cartilage defects were surgically created in the weight-bearing surface of the femoral condyles of both knees, covered by periosteal patches taken from proximal tibia, and sealed with a porcine fibrin glue. In total, 48 condyles were equally allotted to experimental, control, and null groups that were filled beneath the patch with chondrocyte-laden beads in gel, chondrocytes in plain medium solution, or nothing, respectively. The repair was examined 6 months post-surgery on the basis of macroscopic appearance, histological scores based on the International Cartilage Repair Society Scale, and the proportion of characteristic chondrocytes. Tensile stress-relaxation behavior was determined from uniaxial indentation tests. The experimental group scored higher than the control group in the categories of matrix nature, cell distribution pattern, and absence of mineralization, with similar surface smoothness. Both the experimental and control groups were superior to the null group in the above-mentioned categories. Viable cell populations were equal in all groups, but the proportion of characteristic chondrocytes was highest in the experimental group. Matrix stiffness was ranked as null > native cartilage > control > experimental group. Transplanted autologous chondrocytes survive and could yield hyaline-like cartilage. The application of beads and gel for transplantation helped to retain the transferred cells in situ and maintain a better chondrocyte phenotype.

Animals↗

PubMed2005

Bladder acellular matrix as a substrate for studying in vitro bladder smooth muscle-urothelial cell interactions.

The objective of this study was to evaluate the ability of bladder acellular matrix (BAM) to support the individual and combined growth of primary porcine bladder smooth muscle (SMC) and urothelial (UEC) cells. An in vitro co-culture system was devised to evaluate the effect of UEC on (i) SMC-mediated contraction of BAM discs, and (ii) SMC invasiveness into BAM. Cells were seeded onto BAM discs under 4 different culture conditions. Constructs were incubated for 1, 7, 14 and 28 days. Samples were then harvested for evaluation of matrix contraction. Immunohistochemistry (IHC) was utilized to examine cellular organization within the samples and conditioned media supernatants analyzed for net gelatinase activity. BAM contraction was significantly increased with co-culture. The same side co-culture configuration lead to a greater reduction in surface area than opposite side co-culture. IHC revealed enhanced SMC infiltration into BAM when co-culture was utilized. A significant increase in net gelatinase activity was also observed with the co-culture configuration. Enhanced infiltration and contractile ability of bladder SMCs with UEC co-culture may, in part, be due to an increase in gelatinase activity. The influence of bladder UECs on SMC behaviour in vitro indicates that BAM may contain some key inductive factors that serve to promote important bladder cell-cell and cell-matrix interactions.

Animals↗

PubMed2004

Cytotoxic properties of immunoconjugates containing melittin-like peptide 101 against prostate cancer: in vitro and in vivo studies.

BACKGROUND: Monoclonal antibodies (MAbs) can target therapy to tumours while minimising normal tissue exposure. Efficacy of immunoconjugates containing peptide 101, designed around the first 22 amino acids of bee venom, melittin, to maintain the amphipathic helix, to enhance water solubility, and to increase hemolytic activity, was assessed in nude mice bearing subcutaneous human prostate cancer xenografts. METHODS: Mouse MAbs, J591 and BLCA-38, which recognise human prostate cancer cells, were cross-linked to peptide 101 using SPDP. Tumour-bearing mice were used to compare biodistributions of radiolabeled immunoconjugates and MAb, or received multiple sequential injections of immunoconjugates. Therapeutic efficacy was assessed by delay in tumour growth and increased mouse survival. RESULTS: Radiolabeled immunoconjugates and antibodies showed similar xenograft tropism. Systemic or intratumoural injection of immunoconjugates inhibited tumour growth in mice relative to carrier alone, unconjugated antibody and nonspecific antibody-peptide conjugates and improved survival for treated mice. CONCLUSIONS: Immunoconjugates deliver beneficial effects; further peptide modifications may increase cytotoxicity.

Animals↗

PubMed2004

Collagen-hydroxyapatite composite prepared by biomimetic process.

A novel bone graft substitute comprising a porous, collagenous scaffold was biomimetically coated with hydroxyapatite using a simulated body fluid solution chemistry method. The scaffold had a porosity of approximately 85%, with pore sizes between 30 microm and 100 microm. Glutaraldehyde vapor was used to stabilize the collagenous scaffold, giving a significantly increased thermal stability over an unstabilized scaffold, as shown by differential scanning calorimetry. A thin layer (<10 microm) of crystalline hydroxyapatite was deposited onto the stabilized collagenous scaffold by soaking the collagenous construct in simulated body fluid in the presence of calcium silicate glass. The presence of crystalline hydroxyapatite was confirmed by X-ray diffraction, energy-dispersive X-ray spectroscopy, and scanning electron microscopy. In vitro cytotoxicity testing of the composite construct using L-929 fibroblasts (ISO 10993-5) and rabbit periosteal cells revealed a cytocompatible material that supported cellular attachment and proliferation.

Animals↗

PubMed2002

Structure and activity of D-Pro14 melittin.

D-Pro14 melittin was synthesized to investigate the effect of increasing the angle of the bend in the hinge region between the helical segments of the molecule. Structural analysis by nuclear magnetic resonance indicated that, in methanol, the molecule consisted of two helices separated at Pro14, as in melittin. However, the two helices in D-Pro14 melittin were laterally displaced relative to each other by approximately 7 A, and in addition, there was a small rotation of the carboxyl-terminal helix relative to the amino-terminal helix around the long axis of the molecule. The peptide had less than 5% of the cytolytic activity of melittin. Modification of Arg22 with the 2,2,5,7,8-pentamethyl-chroman-6-sulphonyl (pmc) group restored hemolytic activity to close to that of unmodified melittin. Replacement of Arg22 with Phe was less effective in restoring hemolytic activity. Electron-paramagnetic resonance studies suggest that there is a positive correlation between hemolytic activity of the peptides and interaction with phospholipid bilayers.

Cell Death↗

PubMedDate not supplied

Collagen fibril formation in a wound healing model.

Control of tissue composition and organization will be a key feature in the development of successful products through tissue engineering. However, the mechanism of collagen fibril formation, growth, and organization is not yet fully understood. In this study we have examined collagen fibril formation in a wound healing model in which the newly formed fibrils were kept distinct from preexisting tissue through use of a porous tubular biomaterial implant. Samples were examined after 4, 6, 14, and 28 days by light microscopy, in situ hybridization, and immunofluorescence microscopy. These showed a normal wound healing response, with significant collagen formation at 14 and 28 days. Individual collagen fibrils were isolated from these samples by gentle extraction in a gentamicin-containing buffer which allowed extraction of a large proportion of intact fibrils. Examination by transmission electron microscopy showed that approximately 80% of the intact fibrils showed a single polarity reversal, with both ends of each fibril comprising collagen amino-terminal domains; the remaining fibrils had no polarity reversal. All fibrils had similar diameters at both time points. Immunoelectron microscopy showed that all labeled fibrils contained both type I and III collagens. These data indicate that this wound healing model provides a system in which collagen fibril formation can be readily followed.

Animals↗

PubMedDate not supplied

Characterization of a protein-based adhesive elastomer secreted by the Australian frog Notaden bennetti.

When provoked, Notaden bennetti frogs secrete an exudate which rapidly forms a tacky elastic solid ("frog glue"). This protein-based material acts as a promiscuous pressure-sensitive adhesive that functions even in wet conditions. We conducted macroscopic tests in air to assess the tensile strength of moist glue (up to 78 +/- 8 kPa) and the shear strength of dry glue (1.7 +/- 0.3 MPa). We also performed nanomechanical measurements in water to determine the adhesion (1.9-7.2 nN or greater), resilience (43-56%), and elastic modulus (170-1035 kPa) of solid glue collected in different ways. Dry glue contains little carbohydrate and consists mainly of protein. The protein complement is rich in Gly (15.8 mol %), Pro (8.8 mol %), and Glu/Gln (14.1 mol %); it also contains some 4-hydroxyproline (4.6 mol %) but no 5-hydroxylysine or 3,4-dihydroxyphenylalanine (L-Dopa). Denaturing gel electrophoresis of the glue reveals a characteristic pattern of proteins spanning 13-400 kDa. The largest protein (Nb-1R, apparent molecular mass 350-500 kDa) is also the most abundant, and this protein appears to be the key structural component. The solid glue can be dissolved in dilute acids; raising the ionic strength causes the glue components to self-assemble spontaneously into a solid which resembles the starting material. We describe scattering studies on dissolved and solid glue and provide microscopy images of glue surfaces and sections, revealing a porous interior that is consistent with the high water content (85-90 wt %) of moist glue. In addition to compositional similarities with other biological adhesives and well-known elastomeric proteins, the circular dichroism spectrum of dissolved glue is almost identical to that for soluble elastin and electron and scanning probe microscopy images invite comparison with silk fibroins. Covalent cross-linking does not seem to be necessary for the glue to set.

Adhesiveness↗

PubMedDate not supplied

Evaluation for collagen products for cosmetic application.

Collagen is an important component for cosmetic formulation, where it is an effective natural humectant with high substantivity. Commercial collagen preparations have a wide range of properties. In the present study, various techniques have been used to examine three distinct commercial collagens that illustrate the range of properties that are available. The usefulness of the various techniques for assessing collagen quality and batch-to-batch variation is discussed. The results indicate that there are several simple, cheap, and effective methods, such as gel electrophoresis, that provide excellent information on collagen quality. The appropriate selection of tests allows informed decisions on the choice of which collagen preparation to use to provide the desired functionality and shelf life of a formulation.

Amino Acids↗