Post Grafting Research Articles

Canine eruption into grafted alveolar clefts: a retrospective study.

The contemporary treatment of cleft lip and palate involves a sequence of surgical procedures and orthodontic management. Alveolar bone grafting (ABG) is usually undertaken after orthodontic expansion of the maxillary segments between the ages of eight and 12 years. Two of the important goals of alveolar bone grafting are the provision of bony support for the eruption of the canine and the closure of residual oro-nasal fistulae. The purpose of this study was to retrospectively evaluate the root development and eruption of the canine following ABG. Group 1: radiographic and clinical records of a sample of 19 cleft patients who underwent alveolar bone grafting procedures, performed between 1996 and 1999 were reviewed. Group 2: a random sample of 15 cleft patients attending for routine dental review were clinically examined. The age of patient, degree of root development and eruption status of the canine, and presence of oronasal fistulae pre and post alveolar bone grafting were evaluated. Most cleft canines had continued root development and descended in the alveolus towards eruption following ABG. Four canine teeth (8 per cent) were impacted and required surgical exposure and orthodontic treatment following failure of eruption. Closure of anterior oro-nasal fistulae at the time of grafting was maintained post-operatively. This study demonstrated that canine root development and eruption continued satisfactorily through grafted alveolar clefts in most cases and closure of anterior oro-nasal fistulae was achieved in all cases.

The grafting of Rhodamine B onto sol-gel derived mesoporous silicas

Amorphous meseporous silica, silica foams and silica nanotubes have been prepared by the controlled hydrolysis of tetraethoxysilane in various environments. A self-similar structure was obtained in all cases. Rhodamine B was post grafted onto the meseporous silica foam which has been modified with γ-glycidyloxypropyl trimethoxysilane. The grafting and post grafting efficiency of γ-glycidyloxypropyl trimethoxysilane as well as the post grafting efficiency of Rhodamine B on meseporous silica foam were studied, respectively. Basic physicochemical properties of the modified particles are given. When the hybrid pigments were exposed to UV radiation pulses, the emission of the hybrid pigments was increased.

Tops and flops using cultured epithelial autografts in children

The goal of this article is to review the status of cultured epithelial autografts in clinical practice with particular focus on the pediatric subset of patients. The current indications include massive deep burns (>60 - 70% total body surface area), resurfacing-type postburn scar revisions, and skin defect coverage following excision of large skin lesions like giant nevi. Although this method can be lifesaving for massively burned patients, and although excellent functional and cosmetic results may be obtained under ideal circumstances, formidable problems continue to exist. Take is inconsistent, cultured grafts are extremely susceptible to infection, and skin breakdown during the first months post grafting may occur due to mechanical instability of the regenerating skin. It may take one more decade of concerted research, jointly performed by clinicians and tissue culture technology experts in order to fabricate more skin-like grafts which are robust, reliable, and less expensive. Then, "cultured skin" will conquer the world and benefit countless patients.

Vascular Endothelial Growth Pattern During Demineralized Bone Matrix Induced Osteogenesis

The purpose of the current study was to determine the timely ingrowth of blood vessels associated with demineralized bone matrix (DMB) induced osteogenesis. Critical-size (10 × 5mm), full thickness bony defects in rabbit parietal bone were implanted with DBM. Histological and ultrastructural changes were examined 1, 2, 3, 4, 5, 6, 7 and 14 days later. Neovascularization was assessed by immunohistochemical staining for factor VIII antigen (marker for vascular endothelium) and also confirmed by staining using pan-endothelial antibody (CD31) (a marker for endothelium). Immunohistochemical evaluation revealed a positive staining for CD31 and Factor VIII expressed by endothelial cells by day 3 post grafting. By day 4, small blood vessels were first seen budding from host bed towards the grafted DBM. Ultrastructural identification of cells in the early stages of healing revealed the presence of macrophages. The monocyte-derived macrophage appears to play a central role in the repair process using DBM. Results of this study demonstrated a rapid vascularization during the DBM induced osteogenesis. This rapid vascularization is vital to the healing and bone induction ability of the DBM.

Altered patterns of migration of cytokine‐producing T lymphocytes in skin‐grafted naive or immune mice following in vivo administration of anti‐VCAM‐1 or ‐ICAM‐1

Naive or preimmunized (to B10.BR or BALB.k) C3H/HeJ mice received skin grafts from multiple minor histoincompatible B10.BR or BALB.k mice following antigen-specific portal venous (p.v.) pretransplant transfusion, a protocol known to produce prolongation of graft survival in naive animals. In addition, groups of mice received intravenous (i.v.) infusion following transplantation with a mixture of monoclonal antibodies (mAb) to vascular adhesion molecule-1L: very late activation antigen-4 (VCAM-1:VLA-4) or intracellular adhesion molecule-1:lymphocyte function-associated antigen-3 (ICAM-1:LFA-1). Cells were harvested from different tissues of the grafted mice at various times post grafting. RNA was extracted and analysed, using polymerase chain reaction, for expression of different cytokines potentially involved in the regulation of graft rejection [interleukin-2 (IL-2), IL-4, IL-6, IL-10, tumour necrosis factor-alpha, interferon-gamma and transforming growth factor-beta]. In addition, using limiting dilution analysis, we investigated the frequency of allo-specific and third-party reactive cells producing IL-2 and IL-4 in vitro in different tissues of grafted mice following these treatments. The mAb treatment protocol which produced optimum increases in graft survival in naive versus immune mice was different, with anti-LFA-1:ICAM-1 superior for naive mice compared with anti-VLA-4:VCAM-1, and vice versa for immune animals. However, in each case, increased survival was associated with increases local to the graft in the frequency of occurrence of antigen-specific type-2 cytokine-producing cells.

Side chain pendant non‐linear optically active polymers synthesised by grafting reactions on maleic anhydride copolymers

AbstractThe synthesis of well defined, high molecular weight polymers for non‐linear optical (NLO) applications has been carried out in an effort to improve the film properties of waveguides fabricated from these materials, Free radical methods of polymerisation result in molecular weight limitations due to the chain transfer nature of the NLO active chromophores, and therefore, in order to prepare a high molecular weight polymer, a post polymerisation grafting method was chosen to incorporate side chain pendant chromophores onto a preformed polymer. Alcoholysis of anhydride copolymers resulted in chromophore incorporation levels of up to 90% of available reactive sites. Additional branching of the linear anhydride prepolymers was also carried out using polytetrahydrofuran but this was not shown to improve the mechanical properties of the fabricated films. Since the anhydride opens to an ester and an acid, in order to reduce the ionic content of the final polymer, further reaction of the generated carboxylic acid group was attempted, resulting in partial diester formation, and an improvement in film quality. Electrical field poling at temperatures close to the glass transition was only successful at low electrical field strengths, allowing electrooptic coefficients of values of up to 2.4 pm/V at a poling field of 80 V/μm to be obtained.

Primary Amine Implantation Onto Polypropylene Surfaces from Melamine and Urea RF Plasmas.

The possibility of generating tailored surface characteristics (adhesion, biocompatibility, wettability, etc.) from plasma modified surfaces by derivatization and grafting reactions, opens up new possibilities for the creation of advanced materials. Implantation of reactive amine (primary amine) functionalities onto synthetic polymeric surfaces under cold plasma conditions- one of the potential approaches to surface functionalization has been the subject of numerous investigations of recent years. It has been shown that ammonia plasmas do not implant primary amine groups efficiently and consequently, a large number of amine-group containing compounds were tested as alternatives. However, the low volatilities of many of potential aminating agents limit considerably their plasma processing. In this contribution a novel approach of surface amination of PP samples from melamine and urea precoated surfaces is presented. ESCA, ATR-FTIR and ex-situ post plasma grafting reaction data indicate that simultaneous plasma induced evaporation, fragmentation and primary amine implantation processes can be successfully developed. The surface primary-amine concentrations were evaluated by chemical derivatization technique, and the influence of plasma treatment time on the amine group concentrations was investigated.

Histological, Biochemical, and Ultrastructural Studies on Hyperpigmented Human Skin Xenografts

The mechanisms for hyperpigmentation observed in human cutaneous xenografts placed on athymic nude mice was investigated. Histologic, biochemical, histochemical, and ultrastructural examinations were performed on human skin prior to grafting and at various times ranging from 2 weeks to 30 weeks post-grafting (PG). Hyperpigmentation was macroscopically visible on the graft as early as 4-6 weeks. The number of Dopa-positive melanocytes per unit area was increased at 2 weeks PG and remained elevated until 20 weeks PG. The surface area of the melanocytes, a measure of the activity of the cells, also increased significantly and remained above the pre-grafting size throughout the study. Western blot analysis using tyrosinase specific antibody (alpha Ty-SP) revealed the presence of tyrosinase exclusively in the grafted skin from 2 weeks to 12 weeks PG tested. Histological and ultrastructural observations revealed the presence of numerous dendritic melanocytes, indeterminant clear cells suggestive of Langerhans cells, and dermal melanophages. The results of this study suggest that the observed hyperpigmentation in grafted tissue is caused by an increase in the number of Dopa-positive melanocytes and probably from enhanced melanin production. Extracts of proteins from the xenografts exhibited prominent differences in low and high molecular proteins between pre- and post-grafted skin. Among them, the exclusive appearance of a protein doublet with apparent mw approximately 14 kDa was found in grafted skin, and subsequent studies indicate it has potent effects on melanocyte function.

La numération des lymphocytes CD4 permet-elle de prévoir la survenue des pneumonies après transplantation rénale ?

Summary During an outbreak of Pneumocystis carinii pneumonia (PCP), we studied the correlation between CD4 counts and PCP (group 1, n = 10) or other infectious pneumonia (group 2, n = 9) occuring after renal transplantation in 42 patients. CD4 were counted every month post grafting and at the time of infection. CD4 counts were 3 at the time of PCP and during the preceding 30 days in all group 41 patients. Group 1 and group 2 patients had significantly lower counts than all other transplant patients (group 3) : 101 ± 102/mm 3 respectively vs 207 ± 134/mm 3 , p

Radiation initiated grafting onto fluoro polymers for membrane preparation II

A study has been made for the preparation of membranes by the post radiation grafting of acrylamide (AAm) onto poly(tetrafluoroethylene) (PTFE), films. The appropriate reaction conditions were selected under which the graft polymerization was carried out successfully. In this grafting system ammonium ferrous sulphate (Mohr's salt) was used as inhibitor to minimize the homopolymerization of AAm and a suitable concentration of the inhibitor to be added to the reaction medium was found to be 0.05 wt%. The effect of monomer concentration, radiation intensity and temperature on the rate and final degree of grafting was investigated. Increasing grafting temperature rises the initial grafting rate, whereas the final grafting yield increases with temperature up to 45°C, and then declines. This behaviour was described by the influence of glass transition on the rate of termination in the semicrystalline polymer. The overall activation energy for this grafting system was found to be 14.6 and 44.5 kcal/mol above and below 35°C, respectively. Some selected properties of the graft copolymer were studied. It was found that the grafted membranes possess good mechanical and electrical properties and excellent chemical and thermal stability which makes them very promising in practical applications.

The post radiation grafting on vinyl acetate onto poly(tetrafluoroethylene) films

The post radiation grafting of vinyl acetate onto poly(tetrafluoroethylene) film was studied over a wide range of reaction conditions. The effect of solvent, radiation intensity, monomer concentration and temperature on the grafting yield was investigated. The dependence of the grafting rate on radiation intensity and monomer concentration was found to be 0.49 and 1.7, respectively. The final degree of grafting was found to increase with radiation dose and monomer concentration. The overall activation energy for this grafting system was found to be 4.1 and -4.8 kcal/mol above and below 35°C, respectively. Some properties of the graft copolymer such as water uptake and electrical conductivity were also investigated. The graft copolymer films showed good thermal and chemical stability. The possibility of using these grafted membranes in practical applications is very promising.

Post radiation grafting of vinyl acetate onto low density polyethylene films: Preparation and properties of membrane

Reverse osmosis membranes were prepared by the post radiation grafting of vinyl acetate onto low density polyethylene films. The factors affecting the grafting process such as radiation dose, monomer concentration and temperature on the grafting yield were studied. It was found that the dependence of the grafting rate on radiation intensity and monomer concentration was found to be of 0.64 and 1.4 order, respectively. The activation energy for this grafting system was calculated and found to be 4.45 kcal/mol above 30°C. Some properties of the grafted films such as specific electric resistance, water uptake, mechanical properties and thermal and chemical stability were investigated. An improvement in these properties was observed which makes possible the use of these membranes in some practical applications. The use of such membranes for reverse osmosis desalination of saline water was tested. The effect of operating time, degree of grafting and applied pressure on the water flux and salt rejection were determined. The results showed salt rejection percent over 90% and a reasonable water flux. A suitable degree of grafting of the membrane was determined as well as the optimum applied pressure.

Some investigations on the post radiation grafting of acrylamide onto polyethylene films

A study has been made on the post radiation grafting of aqueous acrylamide onto low density polyethylene film. It was found that the addition of 0.05 wt % Mohr's salt reduced effectively the homopolymerization of acrylamide and the grafting process was successfully achieved. The dependence of the grafting rate on the preirradiation dose and monomer concentration was found to be of 1.43 and 1.4 order, respectively. The overall activation energy for the graft polymerization was found to be 13.5 and 1.95 Kcal/mol below and above 45°C, respectively. Some properties of the graft copolymer such as swelling behaviour, electrical conductivity, and reverse osmosis desalination of saline water (water flux and salt rejection), were also investigated and the possibility of its uses in the practical applications was discussed.

Preparation and selected properties of ion-containing reverse osmosis membranes

Ion-containing reverse osmosis membranes were prepared by the post radiation grafting of 4-vinylpyridine onto low density polyethylene films, followed by quaternization of the pyridine rings in the graft chains to confer ionic character to the membranes. The effect of some preparation conditions on the grafting yield was investigated. Different quaternizing agents such as methyl iodide, allyl bromide, and hydrochloric acid were used for the quaternization of the graft chains. The effect of quaternizing agent and degree of grafting on the properties of the membranes such as swelling behaviour, specific electric resistance, water flux and salt rejection, was investigated. The complete quaternization of pyridine rings in the graft chains with methyl iodide and allyl bromide was achieved and the membranes, thus obtained, possess good hydrophilic properties. It was found that the methyl iodide and allyl bromide quaternized membranes gave reasonable water flux and salt rejection. HCl-quaternized membrane, however, gave higher water flux and somewhat lower salt rejection as compared with those obtained for methyl iodide and allyl bromide quaternized ones. The properties of these ionic membranes did not deteriorate with the operation time and they show a great promise for the use in the field of reverse osmosis desalination of sea water.

Post gamma-irradiation grafting of polypropylene film—I: Butadiene: grafting process

The post γ-irradiation grafting of gaseous butadiene to isotactic polypropylene film has been continuously monitored by monomer uptake. Grafting is most efficient to prior annealed polymer in the temperature range 35–45°C. At higher temperatures, competition by radical termination leads to lower graft content. The effect of dose is small initially but increases markedly with conversion. For example after 30 hr at 45°C, the rate is close to second order in dose. The results are compatible with a model for post irradiation grafting to semi-crystalline polymers developed from the literature. Some properties of the copolymer are described.

Use of cyclosporin A in allogeneic bone marrow transplantation in the rat.

ALLOGENEIC bone marrow transplantation (BMT) has become the therapy of choice for the treatment of severe aplastic anaemia and severe combined immunodeficiency diseases and is considered beneficial for the treatment and possible cure of malignant diseases, especially lymphohaematopoietic malignancies1. Several serious complications, however, prevent the full realisation of the therapeutic potential of this procedure. To accept an allogeneic marrow graft, patients (even those treated for aplastic anaemia) have to be conditioned with cytoreductive agents like cyclophosphamide (Cy) or total body irradiation (TBI), agents that have relatively low therapeutic indices for immunosuppression and marked toxicities. Furthermore, patients, even if matched with their respective donors at the major histocompatibility complex (MHC), have after engrafting successfully, a high incidence of potentially fatal graft-versus-host disease (GvHD). Third, patients, who successfully engraft have a severe immunodeficiency for several months after transplantation that apparently contributes to potentially fatal opportunistic infections in the post-grafting period2. Attempts to overcome these complications have had only limited success. Cyclosporin A (Cs A), an undecapeptide of fungal origin3, has been reported to have very profound antilymphocytic activities with very low degrees of myelotoxicity4. It has been shown to suppress a variety of humoral and cellular immune phenomena5, including the rejection of renal allografts in rabbits.6 It seemed reasonable, therefore, to study its effects in an animal model of bone marrow transplantation. Cs A permits the full establishment of a rat marrow graft across the major histocompatibility barrier. Given post grafting it prevents GvHD in an AgB mismatched donor–recipient combination and allows recovery of T-dependent immune functions as early as 28 d after transplantation. Thus, Cs A seems to be a promising agent for use in clinical marrow transplantation.

Closing the Burn Wound

With recent advances in supportive therapy and surgical care, closure of the burn wound now can be accomplished earlier and more effectively than previously. Only by keeping the patient in a state of positive nitrogen balance, immunologically competent, and in equilibrium with the bacteria colonizing the burn wound can early wound closure be carried out with a minimal number of postburn complications.