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Biomedical subjects

M J Citardi

Publications and source records attributed to M J Citardi.

31 records · Page 2Linked to original sources
PubMed1994

Nonvascularized autogenous bone grafts for craniofacial skeletal augmentation and replacement.

Autogenous nonvascularized bone grafts play an important role in the reconstruction of complex craniomaxillofacial defects. Experimental animal data have demonstrated that grafts from membranous bone donor sites tend to undergo less resorption than grafts from endochondral donor sites, probably because of the different bony architecture of each of these types of grafts. Of all the potential donor sites, the harvest of bone graft from the calvarium is associated with the least overall morbidity. Surgeons should be aware of the biologic basis for the successful application of free autogenous bone grafts.

Alveolar Ridge Augmentation↗
PubMed1993

Sequence-dependent cytotoxic effects due to combinations of cisplatin and the antimicrotubule agents taxol and vincristine.

The antineoplastic activity that taxol has demonstrated in advanced ovarian cancer and other neoplasms in which the platinum analogues are among the most active agents has been the impetus for the development of taxol/platinum combination regimens. Since both classes of agents are known to induce cell-cycle-dependent effects and to delay cell-cycle traverse in specific phases of the cycle, an evaluation of drug sequence dependence was incorporated into initial clinical studies of the drug combination. To complement clinical studies, sequence-dependent interactions were assessed in vitro using L1210 leukemia. Cytotoxicity resulting from the combination of taxol and cisplatin was significantly increased over that achieved with cisplatin alone only when cisplatin was administered after taxol. This sequence was significantly superior to both the reverse sequence and to simultaneous drug treatment. Results achieved with sequence iterations of vincristine and cisplatin were nearly identical. In addition, alkaline-elution studies, using the optimal sequence of cisplatin and either taxol or vincristine, demonstrated that these antimicrotubule agents do not increase the formation of cisplatin-induced DNA interstrand and DNA-protein crosslinking over that produced by cisplatin alone. Although the mechanisms for the sequence-dependent cytotoxic interactions between cisplatin and the antimicrotubule agents have not been determined, it is likely that antagonistic interactions occur with the suboptimal sequences, probably because of cell-cycle-dependent phenomena.

Animals↗
PubMed1988

Ergothioneine, histidine, and two naturally occurring histidine dipeptides as radioprotectors against gamma-irradiation inactivation of bacteriophages T4 and P22.

Bacteriophages P22, T4+, and T4os (osmotic shock-resistant mutant with altered capsids) were diluted in 0.85% NaCl and exposed to gamma irradiation (2.79 Gy/min) at room temperature (24 degrees C). T4+ was more sensitive to inactivation than was P22, and the T4os mutant was even more sensitive than T4+. Catalase exhibited a strong protective effect and superoxide dismutase a weaker protection, indicating that H2O2 or some product derived therefrom was predominant in causing inactivation of plaque formation. Low but significant (0.1-0.3 mM) reduced glutathione (GSH) enhanced phage inactivation, but a higher (1 mM) GSH concentration protected. A similar effect was found for the polyamine, spermidine. In contrast, 0.1 mM L-ergothioneine (2-thiol-L-histidine betaine) exhibited strong protection and 1 mM afforded essentially complete protection. L-Ergothioneine is present in millimolar concentrations in some fungi and is conserved up to millimolar concentrations in critical tissues when consumed by man. L-Histidine and two histidine-containing dipeptides, carnosine and anserine, protected at a concentration of 1 mM, a level at which they are present in striated muscles of various animals.

Anserine↗
PubMedDate not supplied

The frontal sinus rescue procedure: early experience and three-year follow-up.

The frontal sinus rescue (FSR), first described in 1997, has now been performed on 24 patients (32 sides) over a period of three years. It is a functional endoscopic surgical approach to correct an iatrogenically scarred and obstructed frontal recess, which cannot be successfully opened via a normal endoscopic frontal sinusotomy approach. It is utilized primarily for patients whose only remaining option is either a Draf-type drill-out (modified intranasal Lothrop) procedure or frontal sinus obliteration. The FSR is a technically challenging procedure, but faster, less difficult, and less destructive for the patient than a "drill-out" or frontal sinus obliteration. Once learned, it can save the patient from undergoing the more radical drill-out or obliterative procedure. The early experience and three-year follow-up with this new endoscopic procedure is presented in our first 24 patients (32 sides).

Adult↗
PubMedDate not supplied

Acellular dermal allograft for sellar reconstruction after transsphenoidal hypophysectomy.

Obliteration of the sphenoid sinus using fat is often used after transsphenoidal hypophysectomy. The morbidity of this approach includes donor site complications, fat necrosis, and delayed mucocele formation. As obliteration with fat is intended to prevent cerebrospinal fluid (CSF) leakage, an alternative for this technique would be techniques used for CSF rhinorrhea repair. Instead of sinus obliteration, these defects are repaired with fascial autografts, which are unfortunately associated with donor site complications. To avoid sinus obliteration and donor site complications, we have reconstructed the sella with acellular dermal allograft in lieu of sinus obliteration. Transsphenoidal hypophysectomy was performed under combined microscopic and endoscopic visualization. For closure, the sellar anterior wall was reconstructed with acellular dermal allograft, septal cartilage/bone autograft, and fibrin glue. The sinus mucosa was then draped over the reconstruction and held in place with microfibrillar collagen hemostat slurry. The sphenoid sinus was not obliterated. Postoperatively, all patients underwent serial nasal endoscopy. Thirteen patients underwent the procedure as described for removal of pituitary adenoma. Postoperative discomfort and pain were minimal. Intraoperative CSF leaks were identified in five patients; none of these patients experienced a postoperative CSF leak. The microfibrillar collagen hemostat was cleared by sphenoid mucociliary clearance. One patient developed acute sphenoid sinusitis several weeks after surgery; this patient did not develop meningitis. One postoperative CSF leak occurred in an obese patient, in whom an intraoperative CSF leak was not identified; this leak resolved with bedrest and delayed lumbar drainage alone. Sellar reconstruction with acellular dermal allograft may eliminate the need for sphenoid sinus obliteration after transsphenoidal hypophysectomy. Acellular dermal allograft sellar reconstruction ultimately provides for an aerated, functioning sphenoid sinus without increased CSF leak risk or potential donor site morbidity.

Female↗
PubMedDate not supplied

The endoscopic management of chronic frontal sinusitis associated with frontal sinus posterior table erosion.

Expansile inflammatory diseases of the frontal sinuses may produce erosion of the posterior table of the frontal sinus. In these instances, the bone between sinus mucosa and intracranial dura is absent. Over the past decade, endoscopic frontal sinusotomy has emerged as the preferred technique for the treatment of refractory chronic frontal sinusitis. Endoscopic approaches also have a role in the most advanced instances of frontal sinusitis. A retrospective chart review of patients who were treated for frontal sinusitis with erosion of the frontal sinus posterior table was performed. Eight patients were identified. All patients underwent endoscopic frontal sinusotomy; some patients required multiple endoscopic procedures. Complete frontal recess dissection with identification of the frontal ostium was achieved for all involved frontal sinuses. In all cases, this postoperative result was monitored by CT scans (where indicated) and serial nasal endoscopy, which demonstrated good frontal sinus aeration and normal mucociliary clearance. Antibiotics were administered for culture-documented bacterial exacerbations, and systemic steroids were given for management of allergic fungal sinusitis and sinonasal polyposis associated with asthma. No patient underwent frontal sinus obliteration or cranialization. No suppurative intracranial complications were noted during the postoperative period. Endoscopic frontal sinusotomy can be used safely for the definitive management of frontal sinusitis associated with posterior table erosion. In fact, endoscopic techniques may represent the preferred approach for the treatment of this problem. Such an approach avoids the morbidity of more destructive alternatives (such as obliteration), and serves to create a frontal sinus with normal mucociliary clearance.

Adult↗
PubMedDate not supplied

Leukotriene B4 levels in rabbit maxillary sinusitis: limitations of the current model.

Since the late 1980s, the rabbit model for sinusitis has been widely used for experimental studies on sinusitis; however, the clinical relevance of these experimental data has been questioned. To elucidate the role of leukotrienes in the pathogenesis of sinusitis, leukotriene B4 (LTB4) levels were determined in acute Streptococcus pneumoniae sinusitis in this model. The rabbit model for acute maxillary sinusitis was utilized. Briefly, the right maxillary ostium of each New Zealand white rabbit was occluded with cyanoacrylate under general anesthesia. Twenty-four hours after occlusion, the occluded sinus received an inoculation of 10(8) Streptococcus pneumoniae (ATCC 10813) or a sham inoculation of saline alone. Rabbits were then sacrificed one week later, and the maxillary sinus mucosae were harvested. Leukotriene B4 levels were determined by ELISA assay. LTB4 levels in the sinuses inoculated with bacteria tended to be higher; however, statistical analysis did not reveal significant differences between the experimental and control groups. It is possible to reliably assess leukotriene B4 levels in this model of sinusitis. Although the data suggest a trend for elevated LTB4 levels, statistical analysis did not support this conclusion. The study also demonstrated significant limitations in the current rabbit model for sinusitis; that is, the standard human sinus bacterial pathogens are minimally pathogenic in rabbit sinuses and the small size of the sinus limits the material available for assay. Further modifications of the model are necessary. After such adjustments, the role of leukotrienes in sinusitis may be further explored.

Acute Disease↗
PubMedDate not supplied

Endoscopically guided frontal sinus beclomethasone instillation for refractory frontal sinus/recess mucosal edema and polyposis.

Despite its metabolic complications, systemic corticosteroid therapy remains a mainstay in the treatment of refractory polyposis after endoscopic frontal sinusotomy. Furthermore, topical nasal corticosteroids often fail, presumably due to the relatively small dosage actually absorbed by the polyps. In order to minimize steroid complications while increasing the locally absorbed dose, beclomethasone (approximately 1 cc, 84 mcg/100 microliters) was instilled under endoscopic guidance directly into the frontal sinus in 31 instances in 16 patients with postoperative frontal recess/sinus polyposis and mucosal edema. The frontal recess/sinus polyposis/edema resolved completely in 9 frontal sinuses, improved considerably in 7 frontal sinuses, improved minimally in 5 frontal sinuses, and remained unchanged in 10 frontal sinuses. No complications were noted. AM cortisol levels remained in the normal range. Endoscopically guided frontal sinus beclomethasone instillation should be considered for the treatment of refractory postoperative frontal sinus/recess polyposis/edema. Further basic and clinical research into the pathophysiology of the nasal mucosa is also warranted.

Absorption↗