Perception of Patients with Amalgam Fillings about Toxicity of Mercury in Dental Amalgam

Objective: The objective of this study is to evaluate the awareness of patients with dental fillings about the toxicity of mercury in dental amalgam. Materials and methods: Adult patients having at least one amalgam filling in their mouth were recruited in the Oral Diagnosis Department of OAUTHC, Ile-Ife Dental Hospital. Participants were recruited consecutively as they report in the clinic. Data were collected using a structured questionnaire developed based on standard questions from relevant publications. They were asked to indicate the type of filling material in their mouth, ingredients of the material, previous knowledge of mercury in dental amalgam and ailments due to mercury. They were to indicate their level of agreement with filling their cavities with dental amalgam despite prior information about its mercury content. Results: There were about 446 respondents analyzed; male, 194 (43.5%); female 252 (56.5%). Six (1.4%) and 21 (4.7%) respondents were primary and secondary schools students respectively; 15(3.4%) had no formal education while about 410 (91.9%) were either undergraduate or graduate. All of them had at least one amalgam filling. 249 (55%) participants know the type of filling on their teeth; 156 (34.5%) had the knowledge of the presence of mercury in dental amalgam while 26.1% believed mercury can cause problems in human beings. About 90 (19.9%) participants claimed to have heard about adverse reactions to dental amalgams and 34 (7.5%) of them have heard about people recovering from an illness after removal of their filling. The level of agreement with filling their cavities with amalgam despite prior knowledge of its mercury content was 74% while 60% was observed for allowing just any material to be placed on their teeth. Conclusion: Awareness of toxicity of mercury in dental amalgam was slightly low among the respondents studied. This may be suggested to be a reflection of nonexistent of global amalgam controversy in Nigeria. Keywords: Patients, Toxicity, Mercury, Amalgam. How to cite this article: Bamise CT, Oginni AO, Adedigba MA, Olagundoye OO. Perception of Patients with Amalgam Fillings about Toxicity of Mercury in Dental Amalgam. J Contemp Dent Pract 2012;13(3):289-293. Source of support: Nil Conflict of interest: None declared.     

Structural basis of collagen fiber degradation by cathepsin K

Cathepsin K is the major collagenolytic protease in bone that facilitates physiological as well as pathological bone degradation. Despite its key role in bone remodeling and for being a highly sought-after drug target for the treatment of osteoporosis, the mechanism of collagen fiber degradation by cathepsin K remained elusive. Here, we report the structure of a collagenolytically active cathepsin K protein dimer. Cathepsin K is organized into elongated C-shaped protease dimers that reveal a putative collagen-binding interface aided by glycosaminoglycans. Molecular modeling of collagen binding to the dimer indicates the participation of nonactive site amino acid residues, Q21 and Q92, in collagen unfolding. Mutations at these sites as well as perturbation of the dimer protein–protein interface completely inhibit cathepsin-K–mediated fiber degradation without affecting the hydrolysis of gelatin or synthetic peptide. Using scanning electron microscopy, we demonstrate the specific binding of cathepsin K at the edge of the fibrillar gap region of collagen fibers, which suggest initial cleavage events at the N- and C-terminal ends of tropocollagen molecules. Edman degradation analysis of collagen fiber degradation products revealed those initial cleavage sites. We propose that one cathepsin K molecule binds to collagen-bound glycosaminoglycans at the gap region and recruits a second protease molecule that provides an unfolding and cleavage mechanism for triple helical collagen. Removal of collagen-associated glycosaminoglycans prevents cathepsin K binding and subsequently fiber hydrolysis. Cathepsin K dimer and glycosaminoglycan binding sites represent novel targeting sites for the development of nonactive site-directed second-generation inhibitors of this important drug target.Cathepsin K (CatK), a papain-like cysteine protease, is predominantly expressed in osteoclasts and held responsible for the degradation of bone collagen (1, 2). Among the 11 known human cysteine cathepsins, only CatK exerts a triple helical collagen hydrolase activity (3). It is capable of disintegrating compact collagen fibers into fragments and to further solubilize them into soluble peptides (4). Excessive CatK activity in humans is associated with osteoporosis, arthritis, and certain bone cancers (5–7). Knock-out studies in mice reveal an impairment of bone resorption reflected by an osteopetrotic bone phenotype (8). Similarly, human CatK deficiency leads to pycnodysostosis, a skeletal dysplasia characterized by dwarfism, generalized osteosclerosis, dysmorphic appearance, and pathologic fractures (9). The crucial role of this protease in collagen fiber degradation is underlined by the finding that osteoclasts as well as fibroblasts from pycnodysostosis specimens accumulate undigested collagen fibrils in their endosomal–lysosomal compartments (10). These findings identified CatK as a well sought-after antiresorptive drug target for the treatment of osteoporosis (11). Presently, several active site-directed small molecular weight inhibitors are in development, with odanacatib having advanced through phase III clinical trials (12).Although the pathophysiological role of CatK has been thoroughly characterized, little is known about the mechanism of collagen fiber degradation by this protease. In contrast with collagenases of the matrix metalloprotease (MMP) family (13, 14), CatK lacks any protein domains implicated in collagen unwinding or specific binding. Structurally, CatK is divided into the left (L) and right (R) domains linked at its center by an interdomain 2-strands beta sheet, creating a V-shaped cleft carrying the active site cysteine (C25) and histidine (H159) residues (15). These structural features are widely conserved among all papain-like cysteine proteases (16) and do not provide mechanistic insights into the collagenolytic activity of CatK. The entrance into the active site of CatK and other cysteine cathepsins is about 5 Å wide and thus too small to accommodate 15-Å-wide triple helical collagen molecules.We have previously shown that the unique and potent collagenase activity of CatK requires the presence of glycosaminoglycans (GAGs) with which it forms high molecular complexes. In the absence of GAGs, CatK only exerts a gelatinase and telopeptide cleaving activity similar to that of other cathepsins (17). This has fueled speculations about a possible role of GAG–CatK complexes in promoting triple helical collagen unfolding by CatK similar to the role the hemopexin domain plays in the hydrolysis of collagens by MMPs (13, 14). Our recently published structure of a complex between E64-inhibited CatK and chondroitin 4-sulfate (C4-S) revealed a “beads-on-a-strand”–like binding of multiple CatK molecules to a single GAG chain (18). However, analysis of the collagenase activity of CatK at the stoichiometric concentrations required to form a beads on a strand–like structure, did not display a significant collagenase activity (17), suggesting that different cathepsin K–GAG complexes must be responsible for collagen degradation.By using X-ray crystallography, mutagenesis, molecular modeling, and electron microscopy, we identified a unique CatK dimer with previously unidentified GAG binding sites and a specific binding site on collagen fibers that reveal a mechanism for the unique activity of this protease.     

Rectal artesunates, their utilization, and parental perception in the management of malaria in children from Abeokuta, southwestern Nigeria

Utilization, efficacy, perception, and acceptability of rectal artesunates for treatment of malaria were assessed in 264 children below 5 years attending two tertiary health facilities in Abeokuta, Nigeria. The children systematically selected were 136 from State Hospital Ijaye and 128 from Federal Medical Centre (FMC), Idi-Aba. Body weights and vital statistics of the children were measured; and blood samples were collected before and 24?h after administration of the rectal artesunates (Plasmotrim-50/200?mg Artesunate) to evaluate the efficacy of the suppository. The first dose of rectal artesunate suppository was administered at a dose of 5-10?mg/kg of body weight per rectum. Giemsa thin and thick films were employed to determine parasite species, malaria parasite count/μL (MPC/μL), and percentage of parasitized red blood cells (PPRBCs). Data were analyzed using SPSS version 16.0. Plasmodium falciparum was the malaria parasite identified by blood examination, with a pretreatment prevalence of 98.9%. Male children had higher infection rate (55%) than females (45%), and infection among age groups and weight groups varied. Chi-square analysis revealed a significant difference between weight and malaria parasite count (p<0.05). Post-treatment analysis after 24?h showed that prevalence dropped by 73%, with females having higher crash rate (77%) than males (69%) but with no statistical difference (p>0.05) among the sexes. Chi-square analysis of pre- and post-treatment revealed a significant difference between MPC/μL and PPRBC at p<0.05. This confirmed the efficacy of rectal artesunate in reducing the parasite density (parasitaemia) within 24?h of treatment. On acceptability, 99.60% of parents accepted to use the suppository. However, 87.1% of parents preferred its usage, as it is easy to administer with no adverse effects when administered on their children. If health officials increase more public knowledge on the use of rectal artesunates, the high mortality now experienced in children under 5 years due to malaria disease would be greatly reduced.     

Awareness and use of medication management services in relation to medication adherence prior to hospitalisation among older adults in Regional Australia

International Journal of Clinical Pharmacy - Background Ageing is associated with changes in physiology, functional ability, declined in cognition and multiple co-morbidities. Alterations in...     

Pulpal sequelae after trauma to anterior teeth among adult Nigerian dental patients

Background  

Epidemiological studies show that about 11.6% to 33.0% of all boys and about 3.6% to 19.3% of all girls suffer dental trauma of varying severity before the age of 12 years. Moderate injuries to the periodontium such as concussion and subluxation are usually associated with relatively minor symptoms and hence may go unnoticed by the patient or the dentist, if consulted. Patients with these kinds of injuries present years after a traumatic accident most of the time with a single discoloured tooth. This study sets out to document the incidence of various posttraumatic sequelae of discoloured anterior teeth among adult Nigerian dental patients.     

Die proximale Humerusschaftfraktur als Komplikation nach der Schlüssellochplastik

Six weeks after operative treatment of a rupture of the long head of biceps brachii using keyhole tenodesis on the left arm in a man 69 years old a fracture of the upper arm happened. The reason seems to be the localization of keyhole osteotomy being probably to much distal.     

Ocular and cerebral metastases in the VX2 rabbit tumor model: contrast- enhanced MR imaging

Ocular and cerebral metastases developed after the inoculation of a VX2 tumor cell suspension into the internal carotid artery of 15 rabbits. The hematogenous spread of tumor cells resulted in ocular metastases in 13 of 15 animals (86.7%) and cerebral system metastases in 14 of 15 animals (93%). Magnetic resonance (MR) imaging with Gd-DTPA demonstrated early disruption of the blood-ocular barrier and blood-brain barrier 5-7 days after infusion of tumor cells. Quantitative assessment of contrast enhancement revealed a mean increase in signal intensity of 145% +/- 51% in the anterior chambers, 102% +/- 70% for choroidal metastases, and 51% +/- 29% for central nervous system (CNS) metastases. These results indicate that contrast-enhanced MR imaging can be used to demonstrate a loss of blood-ocular barrier integrity that is similar to the breakdown of the blood-brain barrier associated with metastatic tumors to the CNS and eye.