Biodegradation of low aqueous concentration pentachlorophenol (PCP) contaminated groundwater.

Bioremedial treatment to remove low level organic contamination to regulatory standards has met with limited success. In this study source water from a contaminated surficial aquifer at a former wood treatment facility was used to evaluate the potential for indigenous microorganisms to degrade low level (< 1.0 mg) pentachlorophenol (PCP) to a regulatory drinking water standard of 0.001 mg/L. PCP degradation was evaluated in series of batch reactors in a two phase study to (a) determine the rate and extent of PCP removal and (b) evaluate the impact of nutrient amendment (N and P) on removal rate. All reactors with the exception of the abiotic control demonstrated PCP removal to a level < 0.002 mg/L within a maximum period of 32 d with and without nutrient amendment. A regression analysis of reactive phosphate (ortho-P) concentration versus removal rate produced an R2 of 0.94 (p = 0.006) indicating a significant correlation between the level of available phosphate and PCP degradation rate. Selective bacterial enumeration (for PCP degrading bacteria) revealed PCP-degrading bacteria increased in abundance prior to and in conjunction with the degradation phase to a density of between 10(3) to 10(4) CFU/ml. Isolates were also analyzed for total fatty acids using Fatty Acid Methyl Ester (FAME) methodology and the results indicated that PCP degrading bacteria were present in the aquifer and consisted of predominately fluorescent, oxidase positive Pseudomonas species. Overall, data indicate that autochthonous microbes are capable of removing low level PCP (< 1.0 mg/L) to approach if not reach the regulatory standard of 0.001 mg/L with the addition of oxygen, with or without nutrient amendment. Results of this research can be applied to full-scale implementation of in-situ or ex-situ bioremediation of groundwater at former wood treatment facilities.

Enhancement of repair in experimental calvarial bone defects using calcium sulfate and dextran beads.

Granular medical-grade calcium sulfate hemihydrate (MGCSH) and negatively charged dextran beads (DB) were evaluated both separately and in combination in cranial defects. Thirty-six rats received bilateral parietal inlay reconstructions using MGCSH, MGCSH plus DB, or DB alone or the defects were left unfilled. Postoperative evaluation at 45, 90, and 135 days was done by visual inspection, caliper measurements of defect thickness, and histologic examination. The best fibro-osseous repair of the defects occurred with the use of MGCSH in combination with DB. Repair tissue, which was confluent with the adjacent cranium, was noted to have good thickness, and a high bone content. By contrast, defects repaired with either DB or MGCSH alone had poorer quality repair tissue, with concavities, voids, bead migration, decreased thickness, and minimal bony replacement/ingrowth. Unfilled control defects showed only a thin, friable, translucent connective tissue layer of repair. No method produced complete bony closure.

Autologous facial fat transplantation: improved graft maintenance by microbead bioactivation.

An alternative approach to the management of free fat transplantation resorption was evaluated in a rat facial model. Fat grafts obtained from the inguinal region were transferred to subcutaneous lateral facial sites in 20 animals. The grafts were mixed with either basic fibroblast growth factor (bFGF) alone or dextran beads that had been pretreated with bFGF. The grafts were then compared by weight and histology at 1 and 6 months postoperatively. Although graft weights were nearly comparable at 1 month, substantial differences were seen at 6 months, with the bead-containing grafts exhibiting near complete weight maintenance and better overall graft form. Histologically, the bead-containing grafts had extensive intercellular collagen formation and a heterogeneity of adipocyte cell sizes, particularly after 1 month. These findings suggest that the addition of cell-specific bioactive peptides that affect either the preadipocyte cell line and/or the fibroblastic components of the recipient site improve postoperative fat graft weight maintenance. Delivery of the biochemical agent appears to require a carrier system to exert its effects.

Effects of nerve growth factor on craniofacial onlay bone graft survival: preliminary findings.

A study was undertaken to evaluate the effects of nerve growth factor (NGF), which had previously demonstrated bone formation around mandibular nerve regenerates, on resorption of onlay bone grafts to the rabbit skull. Iliac grafts were onlayed on the parietal bone bilaterally and immobilized with wire ligatures in 15 animals. NGF and a control solution were introduced into the grafts through subcutaneous osmotic pumps. After 60 days, graft survival was compared by weights, histology, and fluorochrome labels. NGF-treated grafts were characterized by an average of 88.4% weight retention, preservation of the outer cortical plate with firm fixation to the underlying calvarium, and fluorescent labels localized to the inner cortex. Conversely, control grafts had an average weight retention of 42.8% (p < 0.01), nearly complete outer cortical plate loss with increased mobility of the residual inner cortex, and a lack of fluorescence in any part of the grafts. Despite the incongruous name, NGF exhibited a beneficial effect on onlay bone graft volume maintenance in this study. Although the mechanism and the long-term effects are unknown, inhibition of graft resorption rather than enhancement of bone formation is suggested.

Multifocal central giant cell lesions of the maxillofacial skeleton: a case report.

The classification of giant cell lesions of the maxillofacial skeleton is one that remains controversial. Classifying giant cell lesions of the jaw as granulomatous based solely on location seems inappropriate. The categories of benign or malignant are more realistic. Benign lesions may then be subdivided into aggressive and nonaggressive. Multifocal giant cell lesions strongly suggest the brown tumor of hyperparathyroidism. Serum chemistry tests including calcium, phosphorus, ionized calcium, and PTH levels should routinely be obtained when a giant cell lesion is suspected. A case of benign, aggressive, multifocal central giant cell lesions of the maxillofacial skeleton, in the absence of either primary or secondary hyperparathyroidism is presented. Whether this represents metastasis from the initial lesion, metabolic osteoclastic dysfunction, or a new entity, craniofacial giant cell dysplasia, is unknown.

Experimental effects of graft revascularization and consistency on cervicofacial fat transplant survival.

An experimental study evaluating the contributions of graft composition (particulate vs. whole) and revascularization (immediate reanastomosis vs. delayed) to cervicofacial fat transplantation was conducted in rats. Distant (inguinal fat) grafts were bilaterally transplanted to a muscular bed in the cervicofacial region as a free flap (anastomosis to carotid and jugular vessels) or as a free graft (either particulate or whole). Postoperative assessment was made by comparison of pre- and post-operative weights and histologic examination of all specimens, and by acrylic microangiography in select animals of each group. The fat flaps exhibited minimal loss of tissue volume, and showed a normal histologic appearance of the adipocytes and extensive vascular elements within the grafts. Conversely, considerable volume loss occurred in both the particulate and whole fat grafts. Histologically, the free graft was characterized by cellular disruption, atrophic adipocytes, and areas of acellularity. Whole grafts had histologic evidence of vessels located primarily at the periphery, whereas particulate grafts had increased intragraft vessels. Only the fat flaps showed observable intragraft vasculature by microangiography. These findings suggest that reduction of fat grafts into smaller components, eg, by liposuction harvesting, does not improve graft survival or decrease posttransplant resorption.

Tumor vascular permeability factor stimulates endothelial cell growth and angiogenesis.

Vascular permeability factor (VPF) is an Mr 40-kD protein that has been purified from the conditioned medium of guinea pig line 10 tumor cells grown in vitro, and increases fluid permeability from blood vessels when injected intradermally. Addition of VPF to cultures of vascular endothelial cells in vitro unexpectedly stimulated cellular proliferation. VPF promoted the growth of new blood vessels when administered into healing rabbit bone grafts or rat corneas. The identity of the growth factor activity with VPF was established in four ways: (a) the molecular weight of the activity in preparative SDS-PAGE was the same as VPF (Mr approximately 40 kD); (b) multiple isoforms (pI greater than or equal to 8) for both VPF and the growth-promoting activity were observed; (c) a single, unique NH2-terminal amino acid sequence was obtained; (d) both growth factor and permeability-enhancing activities were immunoadsorbed using antipeptide IgG that recognized the amino terminus of VPF. Furthermore, 125I-VPF was shown to bind specifically and with high affinity to endothelial cells in vitro and could be chemically cross-linked to a high-molecular weight cell surface receptor, thus demonstrating a mechanism whereby VPF can interact directly with endothelial cells. Unlike other endothelial cell growth factors, VPF did not stimulate [3H]thymidine incorporation or promote growth of other cell types including mouse 3T3 fibroblasts or bovine smooth muscle cells. VPF, therefore, appears to be unique in its ability to specifically promote increased vascular permeability, endothelial cell growth, and angio-genesis.

Surgical repair of defects in the rabbit temporomandibular joint disc: a comparison of various techniques.

A study was designed to evaluate the effects of different types of repair (suture vs. graft), donor graft tissues (dermis vs. fascia), and methods of graft fixation (sutured vs. laser-assisted) on excisional defects of the rabbit TMJ disc made anterior to the retrodiscal tissue. Groups created to compare the different variables were assessed at 30 and 90 days postoperatively by macroscopic and histologic methods, microangiography, and mechanical strength testing. Without repair, all excisional defects of the disc failed to heal. Suturing of the reapproximated margins did not appear to promote healing or provide much strength beyond the properties of the suture material. Dermal grafts, fixed by suturing, induced healing by becoming incorporated into the disc, restoring discal continuity, and approximating normal disc strength. The use of laser-assisted tissue welding for dermal graft fixation was found to be inadequate and was subsequently abandoned. Fascial grafts could be fixed into position by both suture and laser-assistance, but consistently failed to exhibit successful transplantation and promote healing at the disc site.

Effect of different surgical repair modalities on regeneration of the rabbit mandibular nerve.

A study was designed to evaluate the ability of the rabbit mandibular nerve to regenerate when exposed to crush and resection injuries, as well as to determine how differently sized resection injuries healed when repaired with either autogenous grafts or laminin-lined collagen tubulization. The nerve demonstrated a regenerative capacity over a 1-cm defect, with morphology and function that approximated normals, but could not span a 2-cm gap defect unaided. Crush injuries produced findings that were inferior to both those in normal nerves and in those with resections. In 1-cm defects, both grafting and tubular repairs produced similar results, with substantial recovery of neural function after 16 weeks. In 2-cm defects, autogenous grafting was superior to tubulization by both morphologic and functional assessment. Replacement of the lateral cortex of the mandible after nerve repair was shown to be unnecessary. The implications of these findings as they relate to nerve injury and repair in humans is discussed.

Facial nerve graft repair: suture versus laser-assisted anastomosis.

An experimental study was conducted to evaluate the effectiveness of laser-assisted versus conventional suture repair of facial nerve grafts in the rabbit. Electrophysiologic assessment of function revealed no significant difference between the two techniques. Histological differences were apparent, however, early postoperatively from the effects of heat energy on the perimeter of fascicular morphology. At a later stage, this effect had disappeared. The laser technique was also associated with an apparent decreased escape and entrapment of axons.

Bilateral nasopalatine ducts of the premaxilla.

An unusual case involving the development of patency of the nasopalatine ducts after orthopedic expansion of the premaxilla in a young child is described. The embryogenesis, clinical presentation and surgical repair is discussed.

Surgical treatment of internal derangements of the temporomandibular joint: evaluation of two techniques.

One hundred ten cases of internal derangement of the temporomandibular joint were treated by high condylectomy (47) and eminectomy (63) in combination with discorrhaphy and disc repair. Preoperative and postoperative findings (greater than 24 months follow-up) relating to mandibular mobility, pain, and stability of occlusion were compared. Both procedures resulted in a reduction in symptoms, but differences in postoperative findings were observed. Each procedure resulted in increased translation, with eminectomy patients exhibiting greater opening distances at endstage evaluation. In addition, a greater incidence of residual deviation to the affected side occurred in the majority of high condylectomy patients. Although pain was reduced in both groups, less residual pain was observed in the eminectomy group. Alteration in maxillomandibular centric relation was a rare finding, seen only in two high condylectomy patients. Possible factors contributing to these differences are discussed.

Collagen tube repair of the mandibular nerve: a preliminary investigation in the rat.

A technique for repair of the inferior alveolar nerve of the rat involving a collagen tube conduit with laminin gel lining was compared with unguided regeneration in both large and small nerve gaps. No significant morphologic differences were noted between the groups with small defects. With large defects, however, only the tubular repairs were effective in restoring neural continuity. The implications of the results of this study are discussed.

Secondary management of the premaxilla in bilateral cleft lip and palate patients.

Bilateral clefts of the palate pose difficult and unique problems in surgical rehabilitation. The premaxilla traditionally has been a controversial subject with a historic lack of uniformity in treatment protocol. Based on a review of facial growth and the evolution of premaxillary cleft surgery, principles of management and secondary reconstruction of the premaxilla are discussed. Timely surgical intervention combining osteotomies and bone grafting in conjunction with closure of soft tissue defects is shown to result in satisfactory functional and aesthetic results.

An animal model for advanced microsurgical training.

A model for advanced microsurgical training that uses the cervical neurovascular structures of the rat is presented. Various uses and technical considerations are discussed.

Radiographic and surgical evaluation of internal derangements of the temporomandibular joint.

A prospective study of 287 patients who underwent temporomandibular surgery for disc dysfunction was conducted. The patients were evaluated by combinations of polydirectional tomography, microfocus magnification, and arthrographic radiographic modalities. Abnormalities of the hard and soft tissue structures of the joints were determined radiographically and compared with the findings of surgical examination. Polydirectional tomography and microfocus magnification compared favorably with each other, as well as in their ability to show the actual abnormalities. Arthrography had a high degree of correlation with actual pathologic disc alterations, except for the 15% incidence of false-positive findings of perforation. The combination of either polydirectional tomography or microfocus magnification with arthrography is recommended for complete evaluation of the painful temporomandibular joint that shows evidence of limited range of motion.