Melatonin: an antioxidant at physiological concentrations.
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Animals↗
Biomedical subjects
J M Marchena
Publications and source records attributed to J M Marchena.
Phagocytic function in cyclists: correlation with catecholamines and cortisol.
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.
Adult↗
Anatomic characteristics of the infraorbital foramen: a cadaver study.
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.
Cephalometry↗
Suppression of both basal and antigen-induced lipid peroxidation in ring dove heterophils by melatonin.
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.
Animals↗
Correlation between the circadian rhythm of melatonin, phagocytosis, and superoxide anion levels in ring dove heterophils.
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.
Animals↗
Sensory abnormalities associated with mandibular fractures: incidence and natural history.
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.
Adult↗
EPR studies of spin-labeled bovine plasma amine oxidase: the nature of the substrate-binding site.
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.
Amine Oxidase (Copper-Containing)↗
Melatonin and aging: in vitro effect of young and mature ring dove physiological concentrations of melatonin on the phagocytic function of heterophils from old ring dove.
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.
Aging↗