Fistulotomy with or without marsupialisation of wound edges in treatment of simple anal fistula: a randomised controlled trial.

BACKGROUND: Promotion of healing of the anal wound after fistulotomy may help accelerate recovery and return to work. The present study aimed to assess the effect of marsupialisation of the edges of the laid open fistula track on wound healing after anal fistulotomy for simple anal fistula. METHODS: This was a prospective randomised trial on patients with simple anal fistula. Patients were randomly assigned to one of two groups; group I underwent anal fistulotomy and group II underwent anal fistulotomy and marsupialisation of the edges of the laid open track. Outcomes of the study were time to achieve complete wound healing, operation time, postoperative pain and complications. RESULTS: Sixty patients of mean age of 40.8 years with simple anal fistula were randomly divided into two equal groups. No significant differences between the two groups regarding operation time (16.8 vs 18.4 minutes; P = 0.054), postoperative pain score (1.6 vs 1.2; P = 0.22), and complication rates were recorded. Group II achieved complete healing in a significantly shorter duration than group I (5.1 vs 6.7 weeks; P < 0.0001). CONCLUSION: Marsupialisation of the edges of the laid open fistula track after fistulotomy resulted in quicker wound healing with similar complication and recurrence rates to lay open fistulotomy alone.

Excision with primary midline closure compared with Limberg flap in the treatment of sacrococcygeal pilonidal disease: a randomised clinical trial.

BACKGROUND: Although several surgical techniques for treatment of sacrococcygeal pilonidal sinus (SPND) have been described, there is no consensus on the optimal surgical procedure. In this study we compared excision with primary closure and Limberg flap in the treatment of SPND. METHODS: This was a prospective randomised clinical trial in patients with SPND who were randomly allocated to one of two groups: group I (excision and primary closure) and group II (Limberg flap technique). The primary outcome of the trial was recurrence of SPND whereas postoperative complications, return to work and cosmetic results were the secondary outcomes. RESULTS: Sixty patients were included, with a mean age of 24.1 years and mean body mass index (BMI) of 26.8 kg/m2. Group 1 had significantly shorter operation time than group II. Both groups had similar hospital stay and comparable complication rates (43.3% vs 30%; P = 0.4). Group I had significantly higher recurrence rate (20% vs 0; P < 0.02) and significantly better cosmetic satisfaction score than group II. Being hairy (P = 0.04), positive family history (P = 0.03), diabetes mellitus (P = 0.005) and history of previous surgery for SPND (P = 0.01) were the significant predictors for recurrence. CONCLUSIONS: The Limberg flap is an effective technique for the treatment of SPND with very low recurrence rate and comparable complication rate and hospital stay to excision and primary closure. Excision and primary closure offered the advantages of quicker healing time, earlier resumption of daily activities, better cosmetic results, which may render it more suitable for patients with low risk for recurrence.

Osteoblast cell membrane hybrid bilayers for studying cell-cell interactions.

Osteoblast-like cells were grown on a surface that presents cell membrane components to the cells in culture. The culture surface was a bimolecular layer formed by the interaction of osteoblast plasma membrane vesicles with an alkanethiol monolayer. The potential of these osteoblast-membrane hybrid bilayers for promoting osteoblast adhesion, growth and differentiation was examined. UMR-106 osteoblast-like cells cultured on these surfaces are normal in appearance, and in the presence of serum, proliferate as well or better than on control surfaces. The level of alkaline phosphatase production in the presence and absence of serum suggests that the osteoblast-like cells retain their differentiated phenotype, and appear to respond to the cell surface ligands presented by the osteoblast-membrane biomimetic surface. These observations suggest that biomimetic membrane films prepared from osteoblast cell membranes support osteoblast cell growth, allow the cells to maintain their differentiation state and may be suitable as a model system to probe cell-cell interactions.

Tissue engineered bone-regeneration using degradable polymers: the formation of mineralized matrices.

In the development of 3-dimensional cell-polymer matrices for tissue engineering, the ability of osteoblast cells to maintain their phenotypic properties and form a mineralized matrix while seeded on the polymer surface is very important. Osteoblast cell differentiation and bone formation using rat calvaria cells were studied on the surface of a porous poly(lactide/glycolide)/hydroxyapatite (PLAGA/HA) 3-dimensional polymer matrix. Cell adhesion and proliferation were determined at 24 hr, 3, 7, 14, and 21 days. Cell attachment and proliferation were observed to increase throughout the first two weeks of the study, followed by a period of gradual plateauing of cell numbers. Environmental scanning electron microscopy demonstrated that cells grown on the surface of the 3-dimensional porous PLAGA/HA matrix retained their characteristic morphology and grew in a multi-layer fashion. Light microscopy observations of experiment cultures revealed active osteoblastic cells forming a characteristic mineralized matrix in the presence of beta-glycerophosphate as a phosphate donor. Mineralization did not occur in media either not supplemented with beta-glycerophosphate or when the matrix without cells was incubated with the reagents, indicating that the mineralization was due to the cells and not the HA in the matrix. These results suggest that the 3-dimensional PLAGA/HA matrix could provide a matrix for bone cell differentiation and mineralization in vitro and, therefore, may be a candidate as a synthetic implant for bone regeneration.

An in-vitro evaluation of coralline porous hydroxyapatite as a scaffold for osteoblast growth.

The purpose of this study was to determine the potential of coralline calcium phosphate ceramics to support osteoblast growth for a proposed bone-ceramic composite for skeletal tissue repair. The goal was the development of a matrix with both osteogenic and osteoconductive properties, as compared to ceramic alone, which is solely osteoconductive. MC3T3-E1 osteoblast-like cells were seeded onto sintered and non-sintered porous coralline hydroxyapatite (HA), and onto non-porous hydroxyapatite discs. These in-vitro studies demonstrated that coralline HA supported the growth of osteoblast-like cells. Porous discs supported higher numbers of cells than non-porous discs. Sintering encouraged cell growth, with higher numbers of cells adhered to sintered porous HA discs by day seven. The results suggest that HA can provide a support for osteoblast cells as part of a matrix which may prove to be osteogenic in vivo and may, accordingly, enhance the bone repair process.

Use of polyphosphazenes for skeletal tissue regeneration.

The hydrolytically unstable polyphosphazenes, poly [(imidazolyl) (methylphenoxy) phosphazenes] and poly [ethyl glycinato) (methylphenoxy) phosphazenes], were studied as potential polymeric supports for cells in tissue regeneration. For bone repair, their specific function would be to support osteoblast growth, forming a bone-polymer matrix. MC3T3-E1 cells (an osteogenic cell line) were seeded onto polymer matrices and cell adhesion and growth as well as polymer degradation were examined. Both imidazolyl- and ethyl glycinato-substituted polyphosphazenes supported the growth of MC3T3-E1 cells. An increase in the content of the imidazolyl side group resulted in a reduction in cell attachment and growth on the polymer surface and an increase in the rate of degradation of the polymer. In contrast, substitution with the ethyl glycinato group favored increased cell adhesion and growth and also an increase in the rate of degradation of the polymers. Thus, the polyphosphazenes represent a system whereby cell growth and degradation can be modulated by varying the nature of the hydrolytically unstable side chain. This in vitro evaluation suggests that the polyphosphazenes may be suitable candidate biomaterials for the construction of a cell-polymer matrix for tissue regeneration.

Osteoblast-like cell (MC3T3-E1) proliferation on bioerodible polymers: an approach towards the development of a bone-bioerodible polymer composite material.

An osteogenic cell line (MC3T3-E1) was used to study the potential of bioerodible polymers and ceramics to support osteoblast growth for a proposed bone-polymer composite for skeletal tissue repair. MC3T3-E1 cells were seeded on to 50:50 poly(lactide-co-glycolide), hydroxyapatite, 50:50 hydroxyapatite/poly(lactide-co-glycolide), and the poly(anhydride), poly(bis(p-carboxyphenoxy) propane surfaces. Cell attachment and growth on these surfaces was found to be highest on poly(lactide-co-glycolide), the least on hydroxyapatite and hydroxyapatite/poly(lactide-co-glycolide) combinations gave intermediate values. The order of adhesion and growth of MC3T3-E1 cells on the polymer and ceramic systems was poly(lactide-co-glycolide) is greater than hydroxyapatite/poly(lactide-co-glycolide) which is greater than hydroxyapatite. Negligible growth was found on poly(bis(p-carboxyphenoxy) propane. High alkaline phosphatase activity for the cells grown on poly(lactide-co-glycolide) and hydroxyapatite/poly(lactide-co-glycolide) confirmed retention of the osteoblast phenotype. This in vitro evaluation suggests that poly(lactide-co-glycolide) and hydroxyapatite/poly(lactide-co-glycolide) combinations may be candidate biomaterials for the construction of a cell-polymer matrix for skeletal tissue regeneration.

Prostaglandin-dependent phosphatidylinositol signaling during embryonic chick myogenesis.

Previous investigations suggested that binding of prostaglandin to a myoblast membrane receptor initiates a second messenger cascade which is essential for subsequent myogenesis. Initial evidence of the sensitivity of myogenesis to lithium suggested the involvement of inositol phosphate metabolism. That possibility is investigated here. The accumulation of inositol monophosphate in response to prostaglandin binding was studied in aggregate cultures of chick embryo myoblasts in vitro. At 22 or 28 h in culture mononucleated myoblasts were labeled with [3H]inositol, which was then incorporated into phosphoinositides. After experimental manipulations of prostaglandin metabolism and the addition of Li+ prior to prostaglandin binding at 33 h, [3H]inositol monophosphate accumulation was measured by anion-exchange chromatography between 33 and 37 h. Inositol monophosphate was found to accumulate rapidly following 33 h. However, after 36 h of myogenesis, no inositol monophosphate accumulation was observed. The accumulation was dependent on prostaglandin as indomethacin, which also blocks subsequent membrane events in myogenesis, blocked inositol phosphate accumulation. Like subsequent myogenesis, inositol phosphate accumulation was restored by the addition of exogenous prostaglandin. Finally, the accumulation of inositol phosphate began only after the binding of prostaglandin. The results demonstrate that an inositol phosphate signal transduction mechanism connects prostaglandin binding to membrane events in embryonic chick myogenesis.

Requirement for G protein activity at a specific time during embryonic chick myogenesis.

Signaling between embryonic myoblasts involves prostaglandin metabolism, the activation of a membrane receptor and changes in polyphosphatidyl inositol metabolism. Many of these membrane-localized events occur between 33 to 35 h of differentiation, concomitant with a dramatic change in membrane organization, in myoblast aggregates in culture. Since many receptors affect inositol phosphate metabolism by activating a GTP-binding protein (G protein), we asked if there was evidence for such a protein in myogenic signaling. We show that during the period of differentiation in culture when prostaglandin is needed to bind to a transient receptor, a pertussis toxin-sensitive but cholera toxin-insensitive G protein must act. If this activation is blocked, the characteristic change in myoblast cell adhesion and subsequent membrane fusion do not occur. We suggest that a G protein couples the activated prostaglandin receptor and the change in polyphosphatidyl inositol metabolism and that this membrane transduction step is necessary for subsequent membrane differentiation events during myogenesis.

Rescue of the Li+-induced delay of embryonic myogenesis in vitro by added inositol.

Signaling between embryonic myoblasts to coordinate gene expression is part of normal skeletal muscle development in the embryo. An unanswered question is the nature of the second messengers carrying the information to the nucleus. We have investigated the cell membrane events associated with the binding of prostaglandin to a transient receptor on the embryonic chick myoblast membrane in vitro. The membrane events include a transient change in membrane order seen by electron paramagnetic resonance (EPR), a change in cell-cell adhesion, a rapid decrease in membrane permeability and fusion of the membrane bilayers. The addition of 20 mM Li+, an inhibitor of inositol phosphate phosphatase, perturbed the transient change in membrane order and delayed the change in cell-cell adhesion and conductivity for 2-6 h. Other alkali metal ions had no such effects. The addition of inositol to the culture medium in the continued presence of Li+ restored the normal timing of the two latter events. We interpret this as evidence for an inositol phosphate second messenger system which might connect the activation of the prostaglandin receptor with the change in cell-cell adhesion, the changes in membrane conductivity and perhaps bilayer fusion. We suggest that Li+, by blocking the regeneration of polyphosphatidylinositol from inositol phosphate, reduced the efficiency of the second messenger system such that further differentiation of the myoblast membrane was delayed. The exogenous inositol provided an alternative source and membrane differentiation was unaffected.