ABSTRACT
<p><b>OBJECTIVE</b>To explore the activation of phospho-p38 mitogen activated protein kinases (p-p38MAPK) and to evaluate the possible role of nerve growth factor (NGF) on neuronal protection and regeneration of injured nerve in a model of hypoglossal nerve injury in rats.</p><p><b>METHODS</b>Sixty healthy adult SD rats were divided randomly into three groups: NC control group, NS control group and NGF treatment group. The rats were allowed to survive for 1, 3, 5, 7 and 14 days after operation respectively. Frozen sections were processed for immunohistochemistry (IHC) to decide the p-p38MAPK expression level in the motoneurons of hypoglossal nucleus. Nissi's staining was used to evaluate cellular morphological and architectural changes in the hypoglossal nucleus. Transmission electron microscope (TEM) study was employed to investigate the subcellular structural alternations of the hypoglossal nerve distal to the injury site.</p><p><b>RESULTS</b>The expression level of p-p38MAPK was low in NC group and elevated in all operated animals. However, p-p3SMAPK immunoreactivity in the hypoglossal motoneurons in NGF group was lower than NS control group after injury. The survival rate of motoneurons in hypoglossal nucleus of injured side in NGF group was higher than that in NS group. Ultrastructural study revealed more regenerating myelinated axons which distributed homogenously in the distal site of the lesioned hypoglossal nerve from the NGF group than NS group.</p><p><b>CONCLUSION</b>p-p38MAPK was slightly expression in normal hypoglossal nucleus but intensively expression after injury. NGF can down-regulate p-p38MAPK expression in the motoneurons of hypoglossal nucleus after hypoglossal nerve was crushed. Exogenous NCF can protect damaged neurons and promote nerve regeneration after hypoglossal nerve crush injury in rats.</p>
Subject(s)
Animals , Rats , Hypoglossal Nerve , Motor Neurons , Nerve Growth Factor , Nerve Regeneration , Rats, Sprague-Dawley , p38 Mitogen-Activated Protein KinasesABSTRACT
<p><b>OBJECTIVE</b>To explore the feasibility of methyl thiazolyl tetrazolium (MTT) colorimetric method and the applied condition for the normal bacteria in the mouth, as Streptococcus mutans (S. mutans), Streptococcus sanguis (S. sanguis), Haemophilus actinomycetemcomitans (H. actinomycetemcomitans).</p><p><b>METHODS</b>Colony forming units (CFU) which was the standard antitheses was used to count bacteria. This study would gain some parameters by changing wavelength, reactive time, dosage and so on. MTT colorimetric method was applied in the counting of S. mutans, S. sanguis and H. actinomycetemcomitans.</p><p><b>RESULTS</b>When counting S. mutans, the best wavelength was 510 nm, the best range was 1.5 x 10(5) - 1.0 x 10(7) CFU x mL(-1). When counting S. sanguis, the best wavelength was 545 nm, the best range was 1.5 x 10(5) - 2.0 x 10(7) CFU x mL(-1). When counting H. actinomycetemcomitans, the best wavelength was 557 nm, the best range was 1.0 x 10(6) - 5.0 x 10(7) CFU x mL(-1). MTT colorimetric method can be used for different aged S. mutans, S. sanguis and H. actinomycetemcomitans.</p><p><b>CONCLUSION</b>Oral bacteria could be counted by MTT colorimetric method, which is fast and convenient.</p>