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Biomedical subjects

T Romo

Publications and source records attributed to T Romo.

At least 19 recordsLinked to original sources
PubMed2001

Endoscopic forehead lifting and contouring.

The concept of endoscopic foreheadplasty is based upon a sub- or supraperiosteal dissection of the parietal, occipital and frontal scalp, incision and release of the superior and lateral orbital periosteum, selective myotomies of the brow depressor muscles, and brow elevation into a desired position with fixation and healing. A significant limitation of this procedure appears to be the ability to predict the long-term forehead and brow elevation. We review the anatomy relevant to forehead rejuvenation surgery and present our surgical technique for permanent fixation endoscopic forehead lifting. We discuss the scientific rationale for permanent fixation to ensure long-term forehead and brow position and draw our conclusions based upon the results of animal and clinical studies that have been completed.

Endoscopy↗
PubMed2001

Augmentation of the cheeks, chin and pre-jowl sulcus, and nasolabial folds.

The demand for augmentation of central and lower facial features continues to increase. There are several safe and effective materials available for this purpose, and techniques have become highly refined. The relative strengths and weaknesses of silicone, expanded polytetrafluoroethylene (ePTFE), high-density polyethylene (HDPE), and merseline mesh are discussed for augmentation of the chin/pre-jowl sulcus and cheek. Materials for augmentation of the nasolabial folds (NLF) are also discussed. There are various forms of solid ePTFE that have been developed for soft tissue augmentation. These are particularly well suited for the NLF. Techniques for facial skeletal and soft tissue augmentation are presented.

Biocompatible Materials↗
PubMed2001

Collagen, human collagen, and fat: the search for a three-dimensional soft tissue filler.

As the body ages, not only are the soft tissues of the face subject to gravity but they also may undergo progressive atrophy. Suspensory procedures may return the tissues to a more youthful position, but the atrophic changes are left uncorrected and produce an aged appearance. Three-dimensional (3-D) soft tissue fillers ideally would replace the bulk that was lost. Safety, persistence, and verisimilitude to the native tissues should be optimal in useful 3-D fillers. To date, no such material has been described, but there has been a resurgence in natural materials for this purpose. This article serves as an update on human-derived soft tissue fillers.

Adipocytes↗
PubMed2000

Biology and chemistry of facial implants.

Facial implants have become increasingly more sophisticated in the past 10 to 15 years. The concept of "the ideal implant" has progressed from an inert material that interacts minimally with the host tissue to one that participates in the normal function of the tissues. A thorough understanding of their chemical properties is essential to understand the biologic events that occur around these materials after implantation. This article outlines the salient features of common materials encountered in facial implants used in plastic surgery.

Alloys↗
PubMed2000

Microtia reconstruction using a porous polyethylene framework.

We describe our method for reconstructing microtic auricles using a porous polyethylene framework in two stages. The first stage of the procedure involves rotating a superficial temporoparietal fascial (TPF) flap over the framework. The inferior two-thirds of this framework is next inset into a local temporal skin pocket, while the superior one-third is covered with a full thickness skin graft from the contralateral postauricular sulcus. Lobular transposition is commenced in a second stage procedure at the three-month postoperative period. Hearing restoration surgery is encouraged at a later date in selected patients with unilateral microtia. Use of the porous polyethylene framework permits a more expedient, less invasive, and more reliable method for auricular reconstruction than does the traditional method that employs costal cartilage.

Child↗
PubMed2000

Injectable fillers for facial soft tissue enhancement.

Soft tissue augmentation materials have been advocated for correction of post-surgical or post-traumatic facial defects, as well as for age-related folds and wrinkles. While autogenous tissues may be the safest option, they require a second operative site. Animal-derived or synthetic materials have been advocated since the late 19th century, and have waxed and waned in popularity. In recent years, we have gained a better understanding of the physical events that occur when material is placed within or below the skin. With this knowledge, we stand at the threshold of a new era, where soft tissue fillers can be designed and customized to suit the individual patient. This article will review the major materials that have been or are now advocated for use as soft tissue fillers, and will detail their relative strengths and weaknesses in order to give the clinician a better perspective when considering a material for soft tissue augmentation.

Adipose Tissue↗
PubMed2000

Nasal reconstruction using porous polyethylene implants.

Nasal reconstruction presents a significant challenge to the facial plastic surgeon. The dual goals of reconstruction are restoration of the desired aesthetic nasal contour and an improved nasal airway. Autologous cartilage and bone are considered optimal grafting material, but their supply is often limited and harvesting entails additional morbidity. Many synthetic materials have been introduced in nasal reconstruction, but high infection and extrusion rates limited their use. Porous high density polyethylene implants present an alternative to autologous material as they allow for fibrovascular ingrowth, leading to stability of the implant and decreased rates of infection. Herein we describe the use of porous high density polyethylene implants for reconstruction of the platyrrhine nose and in revision rhinoplasty. The use of preformed nasal-dorsal tip and alar batten implants are described, as well as the use of columellar strut and premaxillary plumper implants. We believe that porous high density polyethylene implants provide a safe, desirable alternative in functional and aesthetic nasal reconstruction.

Biocompatible Materials↗
PubMed2000

Endoscopic foreheadplasty: a histologic comparison of periosteal refixation after endoscopic versus bicoronal lift.

Endoscopic brow lift techniques using temporary fixation rely on rapid readherence of the periosteum to calvarial bone. Little is known about the histologic events that occur during the early postoperative period after these procedures. An animal study was designed to compare and contrast periosteal fixation to bone and unelevated periosteum, with endoscopic and bicoronal brow lift techniques. One method of temporary fixation is the use of absorbable (polylactic/polyglycolic acid copolymer) LactoSorb screws; a histologic analysis of implanted LactoSorb screws was also performed. Sixteen rabbits underwent brow lifts; eight underwent endoscopic brow lift and fixation with LactoSorb screws without skin excision, and another eight underwent traditional bicoronal brow lift with skin excision and closure under tension. Animals were killed 1, 2, 6, and 12 weeks after the procedures were performed to evaluate the interaction of periosteum and bone and the normal, unelevated periosteum/calvarium interface at a site distant from the operative area. Histologic specimens were examined for the degree of apposition of periosteum to bone and for any fibrous or bony reaction at this interface. Histologic analysis showed various degrees of periosteal fibrosis and fixation to calvarial bone. After an initial phase of minimal periosteal adherence and moderate inflammation, the periosteum became progressively more adherent to bone in both groups, with no significant differences between treatment groups in rates of fixation. Fixation required at least 6 weeks. LactoSorb screws were surrounded by an area of mild inflammation and were progressively hydrolyzed and digested. Periosteal fixation increases over time for bicoronal and endoscopic brow lifts with minimal differences between the two techniques. With this animal model, periosteal adherence to calvarium requires at least 6 weeks with complete adherence by 12 weeks. In addition, the use of absorbable fixation screws seems to be both effective and well tolerated. The histologic changes associated with periosteal healing observed in this study suggest that permanent or semipermanent fixation may improve the accuracy and early postoperative maintenance of forehead advancement.

Absorption↗
PubMed1999

Protein-assisted pericyclic reactions: an alternate hypothesis for the action of quantal receptors.

The rules for allowable pericyclic reactions indicate that the photoisomerizations of retinals in rhodopsins can be formally analogous to thermally promoted Diels-Alder condensations of monoenes with retinols. With little change in the seven-transmembrane helical environment these latter reactions could mimic the retinal isomerization while providing highly sensitive chemical reception. In this way archaic progenitors of G-protein-coupled chemical quantal receptors such as those for pheromones might have been evolutionarily plagiarized from the photon quantal receptor, rhodopsin, or vice versa. We investigated whether the known structure of bacteriorhodopsin exhibited any similarity in its active site with those of the two known antibody catalysts of Diels-Alder reactions and that of the photoactive yellow protein. A remarkable three-dimensional motif of aromatic side chains emerged in all four proteins despite the drastic differences in backbone structure. Molecular orbital calculations supported the possibility of transient pericyclic reactions as part of the isomerization-signal transduction mechanisms in both bacteriorhodopsin and the photoactive yellow protein. It appears that reactions in all four of the proteins investigated may be biological analogs of the organic chemists' chiral auxiliary-aided Diels-Alder reactions. Thus the light receptor and the chemical receptor subfamilies of the heptahelical receptor family may have been unified at one time by underlying pericyclic chemistry.

Animals↗
PubMed1999

A brave new world: telemedicine and the facial plastic surgeon.

Telemedicine is defined by the American Medical Association (AMA) as "the provision of health-care consultation and education using telecommunication networks to communicate information." Properly used, telemedicine can provide rapid and easy access to general and specialized medical care. Most telemedical programs have focused on general medical care, but telemedicine can be utilized for subspecialty care. However, technical financial, and legal restrictions must be addressed before more widespread use of telemedicine in facial plastic surgery. This article describes the opportunities and impediments presented to the facial plastic surgeon by telemedicine.

Computer Security↗
PubMed1999

A graduated approach to the repair of nasal septal perforations.

Septal perforation is an avoidable complication of septal surgery, but it can also occur because of a variety of traumatic, iatrogenic, caustic, or inflammatory reasons. Symptoms usually are related to disruption of the normally laminar flow of air through the nasal passages. Crusting, bleeding, parosmia, and neuralgia can develop, leading the patient to seek medical care. When local hygiene and conservative care are unsuccessful in relieving symptoms, closure of the perforation is considered. Repair is often difficult because of the limited exposure and limited amounts of friable mucosa with impaired vascular supply. The failure of attempted closure of septal perforations can be as high as 80 percent. The authors have developed a graduated approach to the closure of septal perforations that tailors the surgical approach to the size and location of the defect. Perforations 0.5 to 2.0 cm in size were closed in 92.9 percent (13 of 14) of patients using an extended external rhinoplasty approach and bilateral posteriorly based mucosal flaps. Larger perforations (2.0 to 4.5 cm) were closed in 81.8 percent (18 of 22) of patients by a two-staged technique, using a midfacial degloving approach to medially advance posteriorly based, expanded mucosal flaps. With careful preoperative management and selection of the appropriate surgical technique, even moderate-to-large perforations can be repaired reliably with limited operative morbidity.

Humans↗
PubMed1998

Characterizing global substates of myoglobin.

BACKGROUND: The massive amount of information generated from current molecular dynamics simulations makes the data difficult to analyze efficiently. Principal component analysis has been used for almost a century to detect and characterize data relationships and to reduce the dimensionality for problems in many fields. Here, we present an adaptation of principal component analysis using a partial singular value decomposition (SVD) for investigating both the localized and global motions of macromolecules. RESULTS: Configuration space projections from the SVD analysis of a variety of myoglobin simulations are used to characterize the dynamics of the protein. This technique reveals new dynamical motifs, which quantify proposed hierarchical structures of conformational substates for proteins and provide a means by which configuration space sampling efficiency may be probed. The SVD clearly shows that solvent effects facilitate transitions between global conformational substates for myoglobin molecular dynamics simulations. Lyapunov exponents calculated from the configuration space divergence of 15 trajectories agree with previous predictions for the chaotic behavior of complex protein systems. CONCLUSIONS: Configuration space projections provide invaluable information about protein motions that would be extremely difficult to obtain otherwise. While the configuration space for myoglobin is quite large, it does have structure. Our analysis of this structure shows that the protein hops between a number of distinct global conformational states, much like the local behavior observed for an individual residue.

Computer Simulation↗
PubMed1998

Reconstruction of the major saddle nose deformity using composite allo-implants.

The major saddle nose deformity leaves a patient with an obvious aesthetic deficit as well as an equally disturbing functional handicap. Reconstructing the collapsed dorsum and tip and simultaneously restoring nasal function present a formidable challenge which has elicited a wide variety of solutions ranging from the use of a toothbrush handle to split calvarial grafting. As Murakami et al pointed out, the "variability exists to a large extent, because the saddle nose deformity is not a single entity but rather a spectrum of abnormalities." Attempts to categorize saddle nose deformities are useful; however, they often lack the simple impact and clarity of the pre-operative photograph. Moreover, the categorizations have not led to a uniform approach to this complicated problem. Nevertheless, Tardy's classification of minimal, moderate, and major saddle nose deformities provides a helpful framework for discussion of reconstructive options. Minimal deformities demonstrate a supratip depression of 1 to 2 mm and are easily corrected with cartilage or fascial overlays. Moderate saddle nose deformities are characterized by a significant loss of dorsal height as well as columellar retraction and broadening of the bony pyramid. A major deformity demonstrates "all of the stigmata of the moderately saddled nose, only to a more marked degree." In Tardy's opinion, an open approach may be warranted in these cases. We offer one solution to the major saddle nose deformity using a composite allo-implant of porous high-density polyethylene (PHDPE) (Medpor surgical implants, Porex Surgical, Inc., College Park, GA) and purified acellular human dermal graft (Alloderm, Life Cell Corp., TX.). While we readily admit that autogenous tissue is the preferred grafting material, we have encountered patients in whom this is not an option. Major saddle nose deformities typically require more augmentation than stacked septal or auricular cartilage can provide. Additionally, in patients seeking revision rhinoplasty, sufficient donor septal or auricular cartilage is often lacking. Resorption of irradiated cadaveric rib grafts has led us away from this material. Split calvarial bone grafts are our next recommendation for these patients; however, many patients refuse this option. In these patients we have turned to a composite allo-implant of PHDPE and acellular human dermal graft for reconstruction of the collapsed dorsum and tip.

Biocompatible Materials↗
PubMed1998

The IL-2/IL-2-receptor complex in the maturation of rat T-cell progenitors.

On the basis of both the interleukin-2-receptor (IL-2R) alpha-chain expression on 16-day-old fetal rat thymocytes and the occurrence of interleukin-2 (IL-2) mRNA-containing cells early during rat thymus ontogeny, we have investigated the possible role of IL-2/IL-2R complex in rat T-cell maturation. For this purpose, we analyzed the effects of the addition of either recombinant rat IL-2 or anti-CD25 (OX-39)-blocking monoclonal antibodies to fetal thymus organ cultures (FTOC), established from 16-day-old rat embryos. IL-2 stimulated the growth of thymocytes and, as a result, induced T-cell differentiation, whereas OX-39 mAb blocked the maturation of thymic-cell progenitors. Accordingly, these results support the involvement of IL-2/IL-2R complex in rat T-cell development.

Animals↗
PubMed1997

Porous high-density polyethylene implants in auricular reconstruction.

OBJECTIVE: To evaluate the ability of porous high-density polyethylene (Medpor) implants to tolerate exposure and support skin grafts when used to reconstruct defects in auricular cartilage in an animal model. DESIGN: Polyethylene implants placed in surgically created defects in auricular cartilage and covered with a skin flap were then exposed at either 4, 7, or 21 days after implantation. The exposed implants were then allowed to heal secondarily or received a skin graft 1 week later. The ability of polyethylene implants to tolerate exposure and support skin grafts was observed clinically and via histological study of the implantation sites. SUBJECTS: Nine adult New Zealand rabbits. RESULTS: Polyethylene implants demonstrated excellent ability to tolerate wound exposure as early as 4 days after implantation, with extrusion of 1 of the 36 implants placed. The degree of secondary wound healing increased as the interval from implantation to exposure increased from 4 to 21 days. Exposed polyethylene implants in all groups also supported all 18 skin grafts placed 1 week after exposure of the implant surface. CONCLUSIONS: Polyethylene implants are well tolerated as replacements for native cartilage in auricular reconstruction. Polyethylene implants tolerated wound exposure as early as 4 days after implantation and demonstrated the ability to heal by secondary intention and support skin grafts. This is likely because of the extent of fibrovascular ingrowth from surrounding tissue, which allows the material to behave more like native tissue and less like a foreign body in this setting.

Animals↗
PubMed1997

Role of IL-2 in rat fetal thymocyte development.

Early during rat thymus ontogeny, an important proportion of thymocytes expresses IL-2R and contains IL-2 mRNA. To investigate the role of the IL-2-IL-2R complex in rat T cell maturation, we supplied either recombinant rat IL-2 or blocking anti-CD25 mAb to rat fetal thymus organ cultures (FTOC) under several experimental conditions. The IL-2 treatment initially stimulated the growth of thymocytes and, as a result, induced T cell differentiation, but the continuous addition of IL-2 to rat FTOC, as well as the anti-CD25 administration, resulted in cell number decrease and inhibition of thymocyte maturation. These results indicate that immature rat thymocytes bear functional high-affinity IL-2R and that IL-2 promotes T cell differentiation as a consequence of its capacity to stimulate cell proliferation. Modifications in TCR alpha beta repertoire and increased numbers of NKR-P1+ cells, largely NK cells, were also observed in IL-2-treated FTOC. Furthermore, IL-2-responsiveness of different thymocyte subsets changed throughout thymic ontogeny. Immature CD4-CD8-cells responded to IL-2 in two stages, early in thymus development and around birth, in correlation with the maturation of two distinct waves of thymic cell progenitors. Mature CD8+ thymocytes maximally responded to IL-2 around birth, supporting a role for IL-2 in the increased proliferation of mature thymocytes observed in vivo in the perinatal period. Taken together, these findings support a role for IL-2 in rat T cell development.

Animals↗
PubMed1997

Septal-myocutaneous flap technique for lower lid blepharoplasty.

Lower lid blepharoplasty can present a significant challenge to the facial plastic surgeon. Routine findings of periorbital fat herniation and dermatochalasia of the lower lid are often associated with the presence of more occult findings, e.g., tarsoligamentous laxity and ectropion. Traditional surgical approaches to the aging lower eyelid utilize the skin flap, the skin-muscle flap, and the transconjunctival technique. The limitation of any one of these procedures alone is that of not addressing the multiple problems of the aging eyelid; this may lead to common postoperative problems of lower lid blepharoplasty, including lid retraction, lagopthalmos, scleral show, rounding of the lateral canthus, and ectropion. We present an integrated surgical solution to the functional and anatomical defects of both the anterior and posterior lamellae, and, when indicated, lateral canthal support. The procedure incorporates a small lateral subciliary and lateral canthal incision with a myocutaneous advancement flap developed in a plane deep to the orbital septum, combined with transconjunctival blepharoplasty for removal of herniated orbital fat. It allows for simultaneous management of the multiple defects of the aging lower eyelid and complete restoration of the relevant anatomy, while avoiding the common pitfalls of lower lid blepharoplasty. We present our experience of 64 patients who underwent bilateral combined septal-myocutaneous advancement flap and transconjunctival blepharoplasty. Indications and postoperative results are reviewed. No complications, including scleral show or ectropion, have been noted over the 4-year postoperative period.

Adipose Tissue↗