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Competing Interests: None disclosed.

We have studied the reaction of allenylboronic acid pinacol ester with cyclopentadiene with experimental and computational methods. The reaction occurred efficiently with complete Diels-Alder periselectivity and regioselectivity at the proximal double bond. The concerted mechanism for the observed transformation was computed to be favored over competitive addition to the distal double bond, [3,3]-sigmatropic rearrangements, and stepwise radical mechanism. This unprecedented Diels-Alder reaction enables the construction of synthetically versatile boron-substituted cycloadducts.

Addressing access to oral health care in many low- to middle-income countries is a complicated issue. Oral and maxillofacial surgeons may help engage with vulnerable populations through carefully planned dentoalveolar mission trips. The process of planning a mission includes selecting a population and identifying their unique needs, designing clinic layouts and workflows, team preparation, collection of supplies, fundraising, and advertising. During the mission, methods for protecting privacy, delivering treatment that is standard of care, and sanitation/sterilization options are reviewed. Ethical considerations include avoiding exploitation of vulnerable populations, offending local hosts, need for data collection, and long-term mission sustainability., Competing Interests: Disclosure The authors have nothing to disclose., (Copyright © 2020 Elsevier Inc. All rights reserved.)

This article reviews evolving and lesser known technologies for tissue cutting and their application in oral and maxillofacial surgery., (Published by Elsevier Inc.)

The essential amino acid tryptophan is the precursor in the anabolic pathway of melatonin, a hormone with immunomodulatory properties. The present study shows the in vivo effect of tryptophan on the phagocytic function and oxidative metabolism of heterophils from Streptopelia roseogrisea of < 1 year of age, with a parallel evaluation of the plasma levels of melatonin. The L-tryptophan was administered orally (125 and 300 mg/kg b.w.) at 19:00, before the beginning of the period of darkness, for 7 days. At the end of the tryptophan treatment, determinations were made at 21:00 and 02:00 of the Phagocytosis Index, the Phagocytosis Percentage, the Phagocytic Efficiency and the superoxide anion levels in heterophils isolated from blood and of the plasma levels of melatonin. The results showed, for the determinations at 21:00 in the animals that had received 125 mg L-tryptophan/kg b.w., enhanced heterophil phagocytic function and raised levels of plasma melatonin, with no affect on the oxidative metabolism of the phagocytes. For the administration of the greater concentration of tryptophan (300 mg/kg b.w.), there were raised plasma melatonin levels together with increases in heterophil phagocytic capacity and phagocyte oxidative metabolism at 02:00. The results indicate that tryptophan administered orally at night to diurnal animals of less than 1 year in age affects the circulating levels of melatonin at the same time as inducing stimulation of the innate immune function.

During intensive exercise the stimulation of phagocytosis is mediated by "stress hormones". During moderate exercise, however, such mediation is less clear. The influence of moderate exercise (45 min at 55% maximal oxygen uptake) on the phagocytic capacity of neutrophils was evaluated in sedentary men. The exercise stimulated phagocytosis of Candida albicans, and the stimulation was maintained for at least 24 h. The possible neuroendocrine mediators were then investigated. Stimulation of phagocytosis was found after incubating neutrophils from sedentary individuals, who were in a basal state, with plasma from exercised individuals. Immediately after exercise, there was a significant increase in the concentration of norepinephrine, but not of epinephrine or cortisol. Incubation of neutrophils with this post-exercise physiological concentration of norepinephrine also stimulated phagocytosis, and the effect was blocked by both propranolol and phentolamine. The norepinephrine-augmented phagocytosis was accompanied by an increase in intracellular levels of cAMP, but not of cGMP or calcium. In conclusion, moderate exercise performed by sedentary people stimulates the phagocytic capacity of neutrophils, and the stimulation lasts for at least 24 h. Norepinephrine mediates the stimulation, although other mechanisms could be involved during the recovery period.

Purpose: The aim of this study was to evaluate our experience and complication rate with the use of a 3-dimensional 2.0-mm curved angle strut plate for mandibular angle fracture fixation., Patients and Methods: This was a retrospective evaluation of 37 patients with noncomminuted mandibular angle fractures fixated with a transorally placed curved 2.0-mm strut plate. Postoperative intermaxillary fixation was used in 5 patients for a mean period of 22 days. A nonchewing diet was prescribed for 6 weeks. Records were reviewed for demographic information, medical history, fracture characteristics, operative management, and complications., Results: Two patients developed infections requiring plate removal and reapplication of fixation. Both of these patients had a molar in the fracture line that was left in place during the first operation. One patient developed a mucosal wound dehiscence without consequence. After a mean follow-up period of 10 weeks, 39.4% of patients with a postinjury/pretreatment inferior alveolar nerve deficit reported a return to normal sensation. All patients who developed a sensory deficit as a result of surgery reported full recovery of sensation. A persistent sensory deficit appeared to be related to fracture displacement., Conclusion: Fixation of noncomminuted mandibular angle fractures with a 2.0-mm curved angle strut plate was predictable. This plate is low in profile, strong yet malleable, facilitating reduction and stabilization at both the superior and inferior borders. Development of a postoperative infection appeared to be related to failure of removal of a molar in the fracture line. The infection rate of 5.4% found in this study compares favorably with that seen with reconstruction plates. Use of this plate did not appear to cause a permanent sensory deficit in this study.

Purpose: The aims of this study were to evaluate the complication rate, the recovery, and the experience in patients undergoing tibial bone harvesting under intravenous sedation., Patients and Methods: This was a prospective study of 10 consecutive patients who underwent unilateral or bilateral sinus grafting with tibial bone grafts under intravenous sedation in a 3-month period in the oral and maxillofacial surgery outpatient clinic. All medications used perioperatively were recorded. Postoperative analgesic requirements were evaluated, along with patient recovery and complications and the patients' subjective experiences., Results: All patients underwent unilateral tibial bone harvesting using a nontrephination technique under sedation with meperidine and methohexital. On average, 11.3 mL of compressed marrow was harvested. All patients described a sensation of scraping intraoperatively but not of severe pain. On average, patients required narcotic analgesics for 1.2 days postoperatively and non-narcotic analgesics for 10.2 days. Discomfort and a gait disturbance were present for an average of 9 to 10 days. There were no wound complications, and all patients were satisfied with the recovery and donor site., Conclusions: Tibial bone harvesting under intravenous anesthesia in an office setting is well tolerated and well accepted. The postoperative recovery and complication rate also seem to compare favorably with those of tibial grafting under general anesthesia., (Copyright 2002 American Association of Oral and Maxillofacial Surgeons)

The possible relationship between the circadian rhythm of blood levels of melatonin and corticosterone in ring dove (Streptopelia risoria) subjected to both immobilization stress and immobilization stress plus dexamethasone treatment were studied. The results show changes in the circadian rhythm of melatonin, with increased daytime levels in situations of stress accompanied by increased corticosterone levels. The highest blood melatonin levels over the 24 h of the study were obtained when the animals were treated with dexamethasone and then subjected to stress. Given the antioxidant role of melatonin, our results support the idea ofmelatonin-corticosterone coupling with the possibility that melatonin released in situations of stress counteracts the adverse effects of glucocorticoids on the organism.

We have studied the circadian rhythm of melatonin in the ring dove (Streptopelia risoria) for different age groups: young (1-1.5 years), mature (3-4 years) and old animals (>8 years). Melatonin levels were determined by radioimmunoassay. Results showed a significant decline in plasma melatonin levels in old animals when compared with the concentrations observed in the other two age groups, in which maximum (nocturnal) concentrations were 300 pg/ml and minimum (diurnal) concentrations were 50 pg/ml. We analyzed the in vitro effect of the physiological concentrations found in young and mature animals on the heterophils obtained from old animals, evaluating the capacity for ingestion and destruction of Candida albicans, and the oxidative metabolism associate to phagocytosis by determining the superoxide anion levels. Melatonin induced an increase in both the phagocytosis index and the candidicide capacity. This effect was dose-dependent. In relation with the oxidative metabolism, a decline in superoxide anion levels after incubation with both concentrations of the hormone was observed. Thus our results corroborate in this avian species the decline in plasma melatonin levels with advanced age, as well as the enhancing effect of physiological concentrations of melatonin on the phagocytic function.

Flow cytometer measurements were made of the basal variations in peripheral blood functional monocytes and granulocytes over the course of a training season (January to November) of a cycling team. Parallel determinations were made of plasma concentration of catecholamines (chromatography) and cortisol (RIA) in a search for neuroendocrine markers. The results showed the greatest phagocytic capacity to occur in the central months (March, May, and July), coinciding with the greatest number and highest level of competitive events with good correlation with a peak in epinephrine during these months (r(2) = 0.998 for monocytes and r(2) = 0.674 for granulocytes). No good correlations were found between phagocytosis and norepinephrine or cortisol. The highest values for phagocytosis and epinephrine concentration were found in May. These results suggest that blood epinephrine concentration could be a good neuroendocrine marker of sportspeople's phagocytic response.

Purpose: The aim of this study was to document the variability in the position of the infraorbital foramen with relation to the facial midline, infraorbital rim, supraorbital notch, and maxillary teeth., Materials and Methods: Forty-seven cadavers (94 sides) were dissected, exposing the infraorbital foramen, supraorbital foramen, and orbital floor bilaterally. Measurements made included (A) distance between the infraorbital foramen and inferior orbital rim; (B) distance of the infraorbital foramen from the facial midline; (C) distance of the supraorbital foramen from the facial midline; (D) distance between the infraorbital foramen and supraorbital foramen. Means, standard deviations, and ranges were determined, and statistical differences were calculated between the left and right orbits and sexes by use of an unpaired sample t-test (P < .05)., Results: In men, the mean distance between the infraorbital foramen and the inferior orbital rim was 8.5 +/- 2.2 mm. In women, this was 7.8 +/- 1.6 mm. The distance between the infraorbital foramen from the facial midline was 27.7 +/- 4.3 mm in males and 26.2 +/- 3.2 mm in females. The mean distance between the infraorbital foramen and supraorbital notch in males was 43.3 +/- 3.1 mm and in females was 42.2 +/- 2.4 mm. The average distance of the supraorbital notch from the midline was 26.5 +/- 3.5 mm in males and 26.3 +/- 3.3 mm in females. There were no statistically significant differences between the left and right sides or between sexes. The maxillary tooth most commonly found in the same vertical plane as the infraorbital foramen was the first premolar. Multiple ipsilateral foramina were found in 15% of cadavers., Conclusion: These anatomic characteristics may have important implications for surgical and local anesthetic planning.

There have been several findings recently concerning melatonin as a free radical scavenger and general antioxidant. For instance, in bird heterophils we found that 100 microM of melatonin decreases superoxide anion levels and modulates superoxide dismutase activity. This paper sought to study the effect of melatonin upon induced oxidative damage in heterophils of the ring dove (Streptopelia risoria). The concentration of malonaldehyde (MDA) as an index of induced oxidative damage to lipid membranes was tested by colorimetric assay. A heterophil suspension was co-incubated with and without inert particles (latex beads) as material to be phagocytosed, both alone and in combination with 100 microM of melatonin. Measurements were made at the basal time (0 min), as well as at 15, 30, 45, and 60 min. Protein concentrations were determined by a standardized method using bovine serum albumin as standard. Results are expressed as nmol MDA/mg prot. Melatonin clearly reduced the production of MDA, an index of lipid peroxidation. It also annulled the enhancement of MDA levels produced by latex beads. Both effects were observed at all the times studied. In conclusion, our findings again show that the neurohormone melatonin could be useful as an effective pharmacological antioxidant.

A functional role for melatonin is its relationship to circadian timing mechanisms. In addition, there has recently been assumed to be a functional connection between the pineal gland and the immune system in mammals and birds, with some findings showing melatonin to be a free radical scavenger and general antioxidant. The present study investigates the possible relationship between the circadian rhythm of melatonin and the ingestion capacity as well as superoxide anion levels of ring dove (Streptopelia risoria) heterophils. In birds, heterophils, with their ability to ingest and kill different antigens, play a central role in the host defence mechanism. All determinations were made during 24 hr periods at 2 hr intervals. Radioimmunoassay showed an increase of melatonin serum levels during the dark period (from 20:00 to 07:00 hr) with a maximum at 04:00 hr, and a significant decline during the hours of light with a minimum at 16:00 hr. Similarly, the phagocytic index was enhanced during the night, with the maximum at approximately 04:00 hr and the minimum at approximately 18:00 hr. The same was the case in relation to phagocytic percentage. However, the superoxide anion levels were lower during darkness (minimum at 04:00 hr) and higher during the light period (maximum at 14:00 hr). In conclusion, our findings show that one pineal-mediated effect on the immune system may be a direct action of melatonin on phagocytosis and the phagocytic biochemical process, and that this neurohormone might act as an antioxidant.

Purpose: The aims of this study were to determine the incidence of inferior alveolar nerve (IAN) abnormalities in patients with mandibular fractures and to document the natural history and spontaneous recovery rate in patients with a sensory disturbance., Patients and Methods: This was a retrospective evaluation of patients (n = 150) with mandibular fractures at risk for IAN injury admitted to the Oral and Maxillofacial Surgery Service between 1985 and 1995. The inclusion criteria were: 1) fractures between the mandibular and mental foramina, 2) availability of the results of a post-injury, preoperative sensory examination, and 3) at least 1 year follow-up. Fracture characteristics, physical examination findings, hospital course, operative treatment, and follow-up were documented. Patient interviews were conducted to determine the incidence of long-term sensory disturbance and associated morbidity. The results were evaluated with chi-square analysis., Results: Fifty-six percent of patients (84 of 150) had a post-injury/pretreatment IAN abnormality. Patients with sensory disturbance had a significantly higher frequency of displaced fractures than those without sensory disturbance (P < .001). Sixteen of 24 patients (66.7%) with an abnormal post-injury/ pretreatment sensory examination reported a permanent sensory deficit (mean follow-up, 74.3 months); 55% of these patients complained of impairment., Conclusions: The incidence of postinjury IAN deficits in patients with mandibular fractures was greater than 50% and was related to fracture displacement. One third of these patients regained normal sensation; the remaining two thirds reported a persistent sensory deficit. A significant number of these patients complained of discomfort and impairment after a mean follow-up of greater than 6 years.

The carbonyl cofactor of bovine plasma amine oxidase (EC 1.4.3.6), recently shown to be 6-hydroxydopa (also known as topa), has been spin labeled to the extent of one label per enzyme dimer molecule, using 4-amino-2,2,6,6-tetramethylpiperidine-N-oxyl (4-amino-TEMPO) and 4-hydrazino-TEMPO followed by reduction with borohydride. By studying the EPR spectra of the labeled enzyme, it has been deduced that there is no magnetic interaction between the copper and the spin label, and that the spin label is at least 1.3 nm distant from the copper(II) ion in the resting enzyme. The bound label is strongly immobilized, is in a sterically constricted environment, and is not accessible to small anions. Removal of the copper does not alter the EPR spectrum of the label. The results are similar to results for porcine plasma amine oxidase, and show that the copper is not close to, and does not directly interact with, the topa-bound substrate.