Mónica López-Peña

Melatonin stimulates osteointegration of dental implants.

Abstract:  The aim of this study was to evaluate the effect of the topical application of melatonin on osteointegration of dental implants in Beagle dogs 14 days after their insertion. In preparation for subsequent insertion of dental implants, upper and lower premolars and molars were extracted from 12 Beagle dogs. Each mandible received cylindrical screw implants of 3.25 mm in diameter and 10 mm in length. The implants were randomly assigned to the mesial and distal sites on each side of the mandible. Prior to implanting, 1.2 mg lyophylized powdered melatonin was applied to one bone hole at each side of the mandible. None was applied at the control sites. Eight histological sections per implant were obtained for histomorphometric studies. After a 2‐wk treatment period, melatonin significantly increased the perimeter of bone that was in direct contact with the treated implants (P < 0.0001), bone density (P < 0.0001), new bone formation (P < 0.0001) and inter‐thread bone (P < 0.05) in comparison with control implants. Topical application of melatonin may act as a biomimetic agent in the placement of endo‐osseous dental implants.

Induction and Inhibition of Apoptosis by Pseudorabies Virus in the Trigeminal Ganglion during Acute Infection of Swine

ABSTRACT We examined the ability of pseudorabies virus (PRV) to induce and suppress apoptosis in the trigeminal ganglion during acute infection of its natural host. Eight pigs were intranasally inoculated with a virulent field strain of PRV, and at various early times after inoculation, the trigeminal ganglia were assessed histologically. PRV-infected cells were detected by use of immunohistochemistry and in situ hybridization, and apoptosis was identified by in situ terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling. Light and electron microscopy was also used for morphological studies. Apoptosis was readily detected among infiltrating immune cells that were located surrounding PRV-infected neurons. The majority of PRV-infected neurons did not show morphological or histochemical evidence of apoptosis, even including those neurons that were surrounded by numerous inflammatory cells and exhibited profound pathological changes. However, neuronal virus-induced apoptosis also occurred but at a sporadic low level. These findings suggest that PRV is able to block apoptosis of infected trigeminal ganglionic neurons during acute infection of swine. Furthermore, our results also suggest that apoptosis of infiltrating inflammatory cells may represent an important viral mechanism of immune evasion.

Topical Application of Melatonin and Growth Hormone Accelerates Bone Healing around Dental Implants in Dogs

BACKGROUND Growth hormone (GH) and melatonin belong to the group of growth factors. These substances have been proposed to improve and accelerate osseous healing using topical applications. PURPOSE The aim of this study was to evaluate the effect of the topical administration of GH and melatonin on osseointegration of dental implants in Beagle dogs 2, 5, and 8 weeks after their insertion. MATERIALS AND METHODS Twelve adult Beagle dogs and 48 implants were used in the study. The maxillary and mandibular premolars and molars were extracted. Each mandible received cylindrical screw implants of 3.25 mm in diameter and 10 mm in length. Prior to implanting, 4 IU of recombinant human GH and 1.2 mg of lyophilized powdered melatonin was applied to one osteotomy at each side of the mandible. None was applied at the control sites. The implants were retrieved at 2, 5, and 8 weeks for light microscopic examination, energy-dispersive x-ray microanalysis, and histomorphometric measurements in ground sections. RESULTS At week 2, BIC was significantly higher in the melatonin-growth hormone group than in the implant control one (34.20 vs 25.05%; p = .010). The M-GH group also increased significantly the peri-implant bone area (64.72 vs 53.20%; p = .038) and interthread bone area (35.62 vs 25.08%; p = .02). At weeks 5 and 8, BIC and bone density around implants were similar to both groups. Significant differences were detected in bone neoformation at 8 weeks in ML-GH group (9.04 vs 7.53%; p = .05). Regarding the mineral composition, in ML-GH group increments in concentrations of phosphorus (10.70 vs 10.34; p = .013) were observed at 2 weeks and of magnesium (0.29 vs 0.25; p = .019) 5 weeks after implantation. CONCLUSION The present study confirms that GH and melatonin synergistically enhance new bone formation around titanium implants in early stages of healing.

L-Particle Production during Primary Replication of Pseudorabies Virus in the Nasal Mucosa of Swine

ABSTRACT Different tissue culture cell lines infected with a number of alphaherpesviruses produce, in addition to virions, light particles (L particles). L particles are composed of the envelope and tegument components of the virion but totally lack the proteins of the capsid and the virus genome; therefore, they are noninfectious. In this electron microscopy report, we show that L particles are produced during primary replication of the alphaherpesvirus pseudorabies virus (PRV) in the nasal mucosa of experimentally infected swine, its natural host. Although PRV infected different types of cells of the respiratory and olfactory mucosae, PRV L particles were found to be produced exclusively by epithelial cells and fibroblasts. We observed that formation of noninfectious particles occurred by budding of condensed tegument at the inner nuclear membrane and at membranes of cytoplasmic vesicles, resulting in intracisternal and intravesicular L particles, respectively. Both forms of capsidless particles were clearly distinguishable by the presence of prominent surface projections on the envelope and the higher electron density of the tegument, morphological features which were only observed in intravesicular L particles. Moreover, intravesicular but not intracisternal L particles were found to be released by exocytosis and were also identified extracellularly. Comparative analysis between PRV virion and L-particle morphogenesis indicates that both types of virus particles share a common intracellular pathway of assembly and egress but that they show different production patterns during the replication cycle of PRV.

Visceral leishmaniasis with cardiac involvement in a dog: a case report

A dog presented with cutaneous nodules, enlarged lymph nodes and oedema in limbs, face and abdomen. The diagnosis of visceral leishmaniasis was established by identification of Leishmania amastigotes within macrophages from skin and popliteal lymph node biopsies. At necropsy, lesions were found in different organs, but it was particularly striking to observe large areas of pallor in the myocardium. Histological examination revealed an intense chronic inflammatory reaction in many organs, and numerous macrophages were found to contain amastigote forms of Leishmania. The inflammatory reaction was especially severe in the heart, where large areas of the myocardium appeared infiltrated with huge numbers of mononuclear immune cells, causing cardiac muscle atrophy and degeneration. Despite the severe inflammation, the number of parasitized macrophages was low in the myocardium, as revealed by immunohistochemical staining of Leishmania amastigotes. Because cardiac involvement is not usually described in this condition, this dog represents a very rare case of canine visceral leishmaniasis with affection of the myocardium.

Bone turnover markers for early detection of fracture healing disturbances: A review of the scientific literature

Imaging techniques are the standard method for assessment of fracture healing processes. However, these methods are perhaps not entirely reliable for early detection of complications, the most frequent of these being delayed union and non-union. A prompt diagnosis of such disorders could prevent prolonged patient distress and disability. Efforts should be directed towards the development of new technologies for improving accuracy in diagnosing complications following bone fractures. The variation in the levels of bone turnover markers (BTMs) have been assessed with regard to there ability to predict impaired fracture healing at an early stage, nevertheless the conclusions of some studies are not consensual. In this article the authors have revised the potential of BTMs as early predictors of prognosis in adult patients presenting traumatic bone fractures but who did not suffer from osteopenia or postmenopausal osteoporosis. The available information from the different studies performed in this field was systematized in order to highlight the most promising BTMs for the assessment of fracture healing outcome.

Evaluation of bone turnover markers and serum minerals variations for predicting fracture healing versus non-union processes in adult sheep as a model for orthopedic research

Bone turnover markers (BTMs) have been considered as an auxiliary method of following the fracture healing process and for early prediction of impaired bone healing. A better understanding of the potential of BTMs in this application could allow for earlier interventions and improved patient care. The aim of this study with a large animal experimental model was to assess the variation of bone formation markers - namely the total alkaline phosphatase (ALP) and its bone-specific isoform (BALP), serum concentration of intact osteocalcin (OC), N-terminal propeptide type III procollagen (PIIINP) and of bone resorption markers - namely tartrate resistant acid phosphatase (TRAP) and deoxypyridinoline crosslink (DPD) during the first stages of a normal fracture healing process and of a segmental critical size defect (CSD), which progresses to a non-union process. Thirty healthy female sheep (Portuguese Churra-da-Terra-Quente breed), approximately 4-years-old, were enrolled in this study. Jugular venous blood samples were collected pre-operatively and at 1, 2, 3, 4, 6, 8, 10 and 12 post-operative weeks. The animals of the CSD group showed significant lower serum levels of BALP, OC and significant higher serum PIIINP levels at early stages of the fracture healing process, compared with animals that progressed in a normal fracture healing process. Serum BALP, OC and PIIINP levels could be useful as non-invasive auxiliary tools with other complementary methods for predicting the outcome of traumatic bone fractures.