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Biomedical subjects

J Zuniga

Publications and source records attributed to J Zuniga.

17 recordsLinked to original sources
PubMed2001

Treatment of fibrous dysplasia of the mandible with radical excision and immediate reconstruction: case report.

Monostotic fibrous dysplasia of the mandible is an unusual manifestation of the disease that is usually benign, occurs in young individuals, and is managed by conservative curettage or debridement. We present a case of persistent fibrous dysplasia complicated by pain and intraoral bony exposure that was successfully managed by radical resection and reconstruction with a free fibular flap. Although mandibular fibrous dysplasia is preferentially managed conservatively, treatment of this disease has evolved to a point where total excision and immediate reconstruction may be the treatment of choice and offer the best outcome.

Adult↗
PubMed2001

Comparing efficacy and safety of four intravenous sedation regimens in dental outpatients.

BACKGROUND: Management of patients' fear and anxiety during dental treatment is a primary concern of dental practitioners. Pharmacological strategies used in outpatient dental settings must be both safe and effective. Regimens of intravenously administered sedative drugs were evaluated in a collaborative, multicenter study of outpatients undergoing removal of impacted third molars. METHODS: A total of 997 patients randomly received one of five treatments: placebo; midazolam administered to a clinical endpoint of conscious sedation (mean dose, 8.6 milligrams); midazolam plus additional midazolam as needed during the procedure (mean total dose, 12.2 mg); fentanyl (1.4 micrograms/kilogram) plus midazolam to achieve the same endpoint of conscious sedation (mean dose, 5.7 mg); or fentanyl (1.4 (micrograms/kg), midazolam (mean dose, 5.8 mg) and methohexital as needed during the procedure (mean dose, 61.0 mg). RESULTS: Each drug regimen reduced anxiety during surgery in comparison with placebo, with the combination of midazolam, fentanyl and methohexital resulting in significantly less anxiety in comparison with the other treatment groups. Pain reports by patients during surgery also were reduced significantly by the combination of fentanyl, midazolam and methohexital. Patients' global evaluations of the efficacy of sedation ranked midazolam with supplemental midazolam and the combination of fentanyl, midazolam and methohexital as significantly more efficacious than the other two drug regiments. The authors noted transient respiratory depression in patients in the two opioid-treated groups, but no other physiological changes were detected. CONCLUSIONS: These data provide evidence that the drugs and doses evaluated resulted in therapeutic benefit to dental outpatients, with minimal incidence of potentially serious adverse effects. CLINICAL IMPLICATIONS: The results of this large-scale study provide assurance to both the public and the dental profession of the safety of parenteral sedation with these drugs and combinations of these drugs when titrated slowly in the recommended doses by appropriately trained dentists.

Ambulatory Surgical Procedures↗
PubMed1996

Augmented reality environment for temporomandibular joint motion analysis.

The principles of interventional video tomography were applied for the real-time visualization of temporomandibular joint movements in an augmented reality environment. Anatomic structures were extracted in three dimensions from planar cephalometric radiographic images. The live-image fusion of these graphic anatomic structures with real-time position data of the mandible and the articular fossa was performed with a see-through, head-mounted display and an electromagnetic tracking system. The dynamic fusion of radiographic images of the temporomandibular joint to anatomic temporomandibular joint structures in motion created a new modality for temporomandibular joint motion analysis. The advantages of the method are its ability to accurately examine the motion of the temporomandibular joint in three dimensions without restraining the subject and its ability to simultaneously determine the relationship of the bony temporomandibular joint and supporting structures (ie, occlusion, muscle function, etc) during movement before and after treatment.

Adult↗
PubMed1993

Inhibition of morphine-induced tolerance and dependence by a benzodiazepine receptor agonist midazolam in the rat.

We investigated whether midazolam administration influenced morphine-induced antinociception and tolerance and dependence in the rat. Antinociception was assessed by the tail-flick (TF) and the hot-plate test (HP 52 degrees C). Morphine tolerance developed after daily single injections of morphine for 11 days. The effect of midazolam on morphine-induced antinociception and tolerance was assessed by giving daily injections of various doses of midazolam for 11 days. The first injection of saline or midazolam was given intraperitoneally and 30 min later morphine (10 mg/kg body weight) was administered subcutaneously. Antinociception was monitored by measuring TF and HP latencies 60 min after the second injection. Midazolam was injected at four different concentrations: 0.03, 0.1, 0.3, and 3 mg/kg body weight. Chronic administration of morphine resulted in the development of tolerance to antinociception in both TF and HP tests, with rats exhibiting baseline antinociception on Day 9. Animals treated with midazolam alone showed little antinociception on Days 3-9. However, midazolam administration in morphine-treated animals attenuated morphine-induced tolerance to antinociception on Days 1-11 as measured by the tail-flick test. Midazolam also decreased the jumping behavior following naloxone injections in morphine-dependent rats. These results suggest that midazolam may prolong the effects of morphine by delaying morphine-induced development of tolerance to antinociception. Midazolam also attenuated a decrease in weight gain induced by chronic injections of morphine.

Animals↗
PubMed1992

Multiphasic effect of morphine on the release of substance P from rat trigeminal nucleus slices.

It is generally accepted that morphine acts presynaptically to inhibit substance P (SP) release from afferent terminals in the trigeminal nucleus. Recent studies, however, provide evidence that opioids produce both inhibitory and excitatory effects on SP release which are concentration- and receptor subtype-dependent. In the present study, we have examined a wide range of morphine concentrations on K(+)-evoked SP release from rat trigeminal nucleus caudalis slices. Immunoreactive SP was measured in perfusates. Morphine produced multiphasic effects on K(+)-evoked SP release without affecting basal release. A very low nanomolar concentration (1 nM) suppressed release, higher nanomolar concentrations (100-300 nM) facilitated release, a low micromolar concentration (3 microM) suppressed release, and a higher micromolar concentration (30 microM) facilitated release. These effects were abolished by opioid receptor blockade with naloxone (30 nM). Thus, morphine produces a complex bi-directional modulation of SP release from TNC which is concentration- and possibly receptor subtype-dependent.

Animals↗
PubMed1987

Nitrous oxide analgesia: partial antagonism by naloxone and total reversal after periaqueductal gray lesions in the rat.

Analgesia induced by nitrous oxide was examined using radiant heat tail flick and electrical evoked foot flick tests in rats. Rats exposed to 80 and 60% nitrous oxide expressed statistically significant elevations of percent analgesia (% MPE) compared to air exposed rats. Rats exposed to 30% nitrous oxide showed no significant difference in percent analgesia. Pretreatment with naloxone (10 mg/kg s.c.) produced a significant decrease in %MPE and an increase in variance of response after exposures to 80% nitrous oxide in a double blind study. Kainic acid lesions of the ventral and caudal periaqueductal grey (PAG) reversed analgesia produced by 80% nitrous oxide in a crossover blink study compared to saline lesions. In conclusion, this evidence suggests that the caudal-PAG-raphe mangus-dorsal horn pain inhibition pathway is in part involved in the analgesia induced by nitrous oxide.

Analgesics↗
PubMedDate not supplied

Effect of contrast media on beta-endorphin secretion. An in vitro study.

The central nervous system may be highly susceptible to the toxic effects of contrast media (CM). Previous experiments demonstrated that vasopressin is released after the intravenous administration of CM. The present study examined the response of the opiocortin system to CM. Neurons of the rat basal hypothalamus, dispersed and attached to Cytodex-3 beads, were perfused with sodium diatrizoate, metrizamide or iohexol (3 mg iodine/ml). The effluent was collected, and the beta-endorphin (B-E) content was measured by a radioimmunoassay technique. Results, normalized to the internal positive control, were compared with release from normal saline (negative control) by analysis of variance. Diatrizoate and metrizamide caused significant release of B-E (p less than 0.03). Iohexol did not stimulate release of B-E. These results suggest that diatrizoate and metrizamide, but not iohexol, can stimulate the release of hormones from hypothalamic neurons. The phenomenon may play a role in some reactions to intravascular CM administration since these neurons are not protected by a blood-brain barrier.

Animals↗