Generation and novel distribution of matrix metalloproteinase-derived aggrecan fragments in porcine cartilage explants.

We have studied aggrecan catabolism mediated by matrix metalloproteinases (MMPs) in a porcine cartilage culture system. Using antibodies specific for DIPEN(341) and (342)FFGVG neoepitopes, we have detected MMP-derived fragments in conditioned medium and cultured cartilage, by radioimmunoassay, Western blotting, and immunolocalization. Radioimmunoassay revealed that the amount (pmol of epitope/mg of total glycosaminoglycan) of (342)FFGVG epitope released from cartilage remained constant over a 5-day culture period and was not increased by IL-1alpha or retinoate. However, the proportion (pmol of epitope/mg of released glycosaminoglycan) of (342)FFGVG epitope released was decreased upon stimulation, consistent with the involvement of a non-MMP proteinase, such as aggrecanase. The data suggest that in vitro MMPs may be involved in the base-line catabolism of aggrecan. Immunolocalization experiments showed that DIPEN(341) and ITEGE(373) epitopes were increased by treatment with IL-1alpha and retinoate. Confocal microscopy revealed that ITEGE(373) epitope was largely intracellular but with matrix staining in the superficial zone, whereas DIPEN(341) epitope was cell-associated and widely distributed in the matrix. Surprisingly, the majority of (342)FFGVG epitope, determined by radioimmunoassay and Western blotting, was retained in the tissue despite the absence of a G1 domain anchor. Interleukin-1alpha stimulation caused a marked increase in tissue DIPEN(341) and (342)FFGVG epitope, and the (342)FFGVG fragments retained in the tissue were larger than those released into the medium. Active porcine aggrecanase was unable to cleave (342)FFGVG fragments at the downward arrowGlu(373) downward arrowAla(374) bond but cleaved intact aggrecan at this site, suggesting that (342)FFGVG fragments are not substrates for aggrecanase. The apparent retention of large (342)FFGVG fragments within cartilage, and their resistance to N-terminal cleavage by aggrecanase suggests that (342)FF6V6 fragments may have a role in cartilage homeostasis.

A randomized, double-blind, placebo controlled comparison of droperidol, ondansetron, and metoclopramide for the prevention of vomiting following outpatient strabismus surgery in children.

STUDY OBJECTIVE: To compare the efficacy of ondansetron, droperidol, or metoclopramide with placebo in preventing postoperative vomiting following strabismus surgery. STUDY DESIGN: Randomized, double-blind, placebo-controlled clinical trial. SETTING: University outpatient surgery center. PATIENTS: 160 ASA physical status I and II children ages 1 to 12 years who were scheduled for strabismus surgery. INTERVENTIONS: Administration of either ondansetron 100 mcg/kg, metoclopramide 250 mcg/kg, droperidol 75 mcg/kg, or placebo intravenously after induction of anesthesia. MEASUREMENTS AND MAIN RESULTS: Both ondansetron and droperidol were superior to metoclopramide and placebo in preventing predischarge vomiting, with incidences of 5%, 5%, 32%, and 25%, respectively. However, there was no difference in the incidence of postdischarge vomiting among the groups (ondansetron 25%, droperidol 25%, metoclopramide 20%, and placebo 25%). CONCLUSIONS: While both ondansetron and droperidol are more effective than metoclopramide when compared with placebo in decreasing the incidence of predischarge vomiting, none of these drugs was more effective than placebo in decreasing the incidence of postdischarge vomiting. Recovery from anesthesia was not significantly different among the groups as assessed by time to awakening, initial Steward score, and time to discharge.

Small-dose propofol by continuous infusion does not prevent postoperative vomiting in females undergoing outpatient laparoscopy.

This study was designed to test the hypothesis that there is a direct prophylactic antiemetic effect of small-dose propofol given by continuous infusion. Sixty female patients undergoing outpatient laparoscopy under general anesthesia were randomized to receive, in a double-blind fashion, either a bolus of 0.1 mg/kg followed by a constant infusion of 1 mg.kg-1.h-1 of propofol or an equivalent volume of 10% Intralipid (placebo) beginning 30 min before induction of anesthesia and continuing until discharge from Stage I postanesthesia care unit (PACU). Anesthesia was induced and maintained in a standard fashion in all patients. The number of emetic episodes before and after discharge from PACU, nausea scores (11-point numerical scale), and time to discharge were evaluated. No significant differences between Intralipid and propofol were found for any of the outcome variables tested. While small-dose propofol is an effective adjuvant in reducing chemotherapy-induced emesis, we were unable to demonstrate any beneficial effect of propofol in reducing postoperative nausea and vomiting when used as the sole prophylactic medication in this patient population. Propofol may have a synergistic effect when administered with other antiemetics, or the specific antiemetic effect of propofol, if it exists, may be dose-dependent and the dose used in this study was below the efficacy threshold.

Oxygen administration during transport and recovery after outpatient surgery does not prevent episodic arterial desaturation.

STUDY OBJECTIVE: To compare the efficacy of two different oxygen (O2) delivery systems in preventing episodic arterial desaturation in the immediate postoperative period. STUDY DESIGN: Randomized, prospective, nonblinded comparison in patients. SETTING: Operating room and postanesthesia care unit (PACU) of a university outpatient surgery center. PATIENTS: 100 ASA status I and II adults, male and female, age greater than 18 years, undergoing outpatient surgical procedures not involving the upper airway. INTERVENTIONS: Group I received supplemental O2 administered by bag-valve-mask during transport, followed by 40% face shield in the PACU. Group 2 received supplemental O2 by nasal cannula at 4 L/min both during transport and during PACU stay. MEASUREMENTS AND MAIN RESULTS: Arterial O2 saturation (SpO2) was collected by computer from a recording pulse oximeter at 15-second intervals beginning before extubation and continuing until O2 administration was discontinued in PACU. Neither mode of therapy was successful in completely eliminating arterial desaturation defined as SpO2 less than 90%, nor was there any difference in efficacy between the two treatment groups. Group 1 had 8 patients desaturate on 9 different occasions (5 times during transport, 4 times in PACU). Group 2 had 5 patients desaturate on 9 different occasions (4 times during transport, 5 times in PACU). CONCLUSION: Routine O2 administration during transport and PACU stay did not abolish episodic desaturation, even in healthy patients undergoing minor surgical procedures. Given the marked difference in acquisition cost, it would appear that O2 administration by nasal cannula is a more cost-effective alternative for routine postoperative O2 administration in certain groups of patients undergoing general anesthesia for outpatient surgery.

Surgical coverage of exposed root surfaces: a review of available techniques and applications.

Exposed root surfaces often create esthetic problems with less-than- satisfactory restorative solutions. Gingival recession may result in thermal and tactile sensitivity that is unresponsive to treatment with desensitizing agents. Surgical procedures for the coverage of exposed root surfaces have provided successful and highly predictable results even in deep, wide areas of recession. This article reviews the available procedures and discusses the indications for periodontal plastic surgery. Clinical cases are presented that demonstrate solutions to commonly encountered clinical problems that result from gingival recession.

Proximal large-bore jet ventilation for laryngeal laser surgery.

The carbon dioxide surgical laser has made many open upper airway operations obsolete. However, new laser-related hazards have been encountered, the most serious of which is fire in the airway. Venturi jet ventilation removes that risk and provides an unobstructed surgical field. Indications and techniques for the use of jet ventilation with carbon dioxide laser surgery remain controversial, particularly whether jet ventilation should be used in papillomatosis or in the severely obstructed airway, and whether proximal and distal catheter techniques are equally safe and effective. We report the successful use of proximal large-bore Venturi jet ventilation in 327 consecutive patients undergoing microlaryngeal laser surgery. The technique is ideal for pediatric patients with subglottic stenosis or recurrent respiratory papillomas and has not caused distal seeding in the latter group. We recommend the use of low-pressure ventilation, even in relatively obstructed airways. The experimental evidence reported here corroborates the clinical viewpoint expressed; the technique is safe, simple, and uncomplicated if used with care.

Laboratory investigation of six artificial noses for use during endotracheal anesthesia.

The performances of six commercially available heat and moisture exchangers (HMEs) or "artificial noses," were evaluated in the laboratory. Each HME was studied with both a semiclosed anesthesia circuit (SCAC) and a nonrebreathing anesthesia system (NRS). Our results suggest that the Servohumidifier 150 and the Engström Edith are suitable for replacing nasopharyngeal humidification mechanisms bypassed during endotracheal ventilation in all patients because they provided at least 20 mg of water per liter of minute ventilation (mg/L) in an NRS and 28 mg/L in an SCAC during inspiration. While the other four units were suitable for small tidal volumes, they only marginally satisfied minimal suggested humidity levels in the presence of larger tidal volumes.