Exploring the role of the dental hygienist in reducing oral health disparities in Canada: A qualitative study.

OBJECTIVES: Reducing oral health disparities has been an ongoing challenge in Canada with the largest burden of oral disease exhibited in vulnerable populations, including Aboriginal people, the elderly, rural and remote residents, and newcomers. Dental hygienists are a unique set of professionals who work with and within communities, who have the potential to act as key change agents for improving the oral health of these populations. The purpose of this qualitative study was to explore, from the dental hygiene perspective, the role of dental hygienists in reducing oral health disparities in Canada. METHODS: Dental hygienists and key informants in dental hygiene were recruited, using purposeful and theoretical sampling, to participate in a non-directed, semi-structured one-on-one in-depth telephone interview using Skype and Call Recorder software. Corbin and Strauss's grounded theory methodology was employed with open, axial, and selective coding analysed on N-Vivo Qualitative software. RESULTS: The resulting theoretical framework outlines strategies proposed by participants to address oral health disparities; these included alternate delivery models, interprofessional collaboration, and increased scope of practice. Participants identified variation in dental care across Canada, public perceptions of oral health and dental hygiene practice, and lack of applied research on effective oral health interventions as challenges to implementing these strategies. CONCLUSION: The research confirmed the important role played by dental hygienists in reducing oral health disparities in Canada. However, due to the fragmentation of dental hygiene practice across Canada, a unified voice and cohesive action plan is needed in order for the profession to fully embrace their role.

Epididymal mitochondrial status of hypothyroid rats examined by transmission electron microscopy.

Hypothyroid rats show alterations in the mobility of sperm recovered from their epididymides. The AgNOR technique, immunohistochemistry and transmission electron microscopy were used to investigate changes in epithelial cells from epididymides of rats treated with (131)I. Counting of NORs did not permit detection of changes in the proliferative capacity of epididymides of hypothyroid animals. Transmission electron microscopy revealed changes in the mitochondria of hypothyroid rats that probably are associated with incipient apoptosis.

AgNOR, p16 and human papillomavirus in low-grade squamous intra-epithelial lesions of the uterine cervix. Preliminary report.

It has been shown that infection with high-risk human papillomaviruses (HR-HPV) is related to the development of cervical cancer. The persistence of the virus in intra-epithelial lesions of cervix uteri (SILs) is the basis for the application of HPV testing for screening and management of patients. Most infections by HR-HPVs resolve spontaneously, however, and do not progress to dysplasia or cancer. p16INK4a is a useful biomarker of cervical intra-epithelial neoplasia and could be a marker for the progression of low-grade squamous intra-epithelial lesions (LSILs) to high-grade squamous intra-epithelial lesions (HSILs), because it correlates independently with increasing SIL grade. We conducted a preliminary histological study of 28 patients diagnosed with LSIL, HSIL or nondysplastic epithelium (NDE) from whom 28 biopsies of uterine cervix and 28 endocervical brushed biopsies were taken. Argyrophilic nucleolar organizer region (AgNOR) and p16INK4a assays were performed on the biopsies, and endocervical brushings were used for HPV typing. The high risk HPV group showed that the number of patients with AgNOR areas greater than 3.3 µm(2) and with expression of p16INK4a were statistically greater than the number of lower risk patients. None of the biopsies of LR-HPV carriers expressed p16 and AgNOR areas> 3.3 µm(2) simultaneously. Four LSILs and the NDE of this group expressed neither of the two markers. If the correlation between AgNOR areas and p16INK4a is good, we may be able to develop a low cost simple technology for studying patients infected with HR-HPV and diagnosed with LSIL of uncertain behavior.

Prevalence of early childhood caries among First Nations children, District of Manitoulin, Ontario.

BACKGROUND: Epidemiological studies of Aboriginal communities in Canada and Native American populations in the United States have reported that early childhood caries (ECC) is highly prevalent. The purpose of this study was to determine the prevalence of ECC and dental caries in the First Nations population of 3- and 5-year-old children in the District of Manitoulin, Ontario to assist in developing effective dental health promotion strategies. METHODS: All 3- and 5-year-old children in elementary schools and day-care centres in seven First Nation communities were eligible for the survey examination. Three-year-old children at home and 5-year-old children attending school off-reserve in six of the communities were also eligible for epidemiological survey examination of oral health status including caries, gingival and soft tissue conditions. Cases of ECC were defined as children with caries or restorations on two or more primary maxillary incisors or canines or those having a total decayed, missing, filled primary teeth (dmft) score of 4 or greater. RESULTS: A total of 87 children (59% 5 years old, 54% females) were examined. Seventy-four per cent of children had one or more carious lesions. Forty-five cases of ECC were found, a prevalence of 52%. The mean dmft score for cases was 7.5 (95% CI 6.5-8.4) and 0.8 (95% CI 0.5-1.1) for non-cases (P < 0.001). Boys in both age groups were more likely to be affected by ECC than girls. CONCLUSION: Our results indicate that dental caries and ECC are highly prevalent in this population, with ECC cases having 6.7 more dmft than non-cases.

Ultrastructural study of reaggregated culture of brainstem: synaptogenesis.

The synaptogenesis and the morphological differentiation of neural cells were studied in aggregating cultures. Brainstems of 14-15 days old rat embryos were removed and the area located between the mesencephalic flexure and the caudal portion of metencephalon was dissected and mechanically dissociated to single cells. These cells reassociated forming highly organized aggregates in which differentiation took place. Samples were harvested after different time periods, fixed and processed for electron-microscopic study. After one day in culture the aggregates were composed by rounded undifferentiated cells. These cells had a high nuclear/cytoplasmic relation, were devoid of processes and were separated by great intercellular spaces. At the end of the first week of culture cell differentiation and extension of processes were evident. A loose neuropil appeared: it was composed by abundant growing neurites and growth cones. Later, the neuropil became more compact and glial processes and synaptic terminals filled with vesicles appeared. The early appearance of vesicles in the synaptic endings was the first evidence of synaptogenesis. Post and presynaptic membrane densities appeared later, and fully mature synaptic contacts were seen by the end of the 3rd week in culture. Scarce myelin sheaths were observed after 35 days in vitro.

Ultrastructural study of reaggregated culture of brainstem: synaptogenesis

The synaptogenesis and the morphological differentiation of neural cells were studied in aggregating cultures. Brainstems of 14-15 days old rat embryos were removed and the area located between the mesencephalic flexure and the caudal portion of metencephalon was dissected and mechanically dissociated to single cells. These cells reassociated forming highly organized aggregates in which differentiation took place. Samples were harvested after different time periods, fixed and processed for electron-microscopic study. After one day in culture the aggregates were composed by rounded undifferentiated cells. These cells had a high nuclear/cytoplasmic relation, were devoid of processes and were separated by great intercellular spaces. At the end of the first week of culture cell differentiation and extension of processes were evident. A loose neuropil appeared: it was composed by abundant growing neurites and growth cones. Later, the neuropil became more compact and glial processes and synaptic terminals filled with vesicles appeared. The early appearance of vesicles in the synaptic endings was the first evidence of synaptogenesis. Post and presynaptic membrane densities appeared later, and fully mature synaptic contacts were seen by the end of the 3rd week in culture. Scarce myelin sheaths were observed after 35 days in vitro

Ultrastructural study of reaggregated culture of brainstem: synaptogenesis

The synaptogenesis and the morphological differentiation of neural cells were studied in aggregating cultures. Brainstems of 14-15 days old rat embryos were removed and the area located between the mesencephalic flexure and the caudal portion of metencephalon was dissected and mechanically dissociated to single cells. These cells reassociated forming highly organized aggregates in which differentiation took place. Samples were harvested after different time periods, fixed and processed for electron-microscopic study. After one day in culture the aggregates were composed by rounded undifferentiated cells. These cells had a high nuclear/cytoplasmic relation, were devoid of processes and were separated by great intercellular spaces. At the end of the first week of culture cell differentiation and extension of processes were evident. A loose neuropil appeared: it was composed by abundant growing neurites and growth cones. Later, the neuropil became more compact and glial processes and synaptic terminals filled with vesicles appeared. The early appearance of vesicles in the synaptic endings was the first evidence of synaptogenesis. Post and presynaptic membrane densities appeared later, and fully mature synaptic contacts were seen by the end of the 3rd week in culture. Scarce myelin sheaths were observed after 35 days in vitro (AU)

Ultrastructural study of reaggregated culture of brainstem: synaptogenesis.

The synaptogenesis and the morphological differentiation of neural cells were studied in aggregating cultures. Brainstems of 14-15 days old rat embryos were removed and the area located between the mesencephalic flexure and the caudal portion of metencephalon was dissected and mechanically dissociated to single cells. These cells reassociated forming highly organized aggregates in which differentiation took place. Samples were harvested after different time periods, fixed and processed for electron-microscopic study. After one day in culture the aggregates were composed by rounded undifferentiated cells. These cells had a high nuclear/cytoplasmic relation, were devoid of processes and were separated by great intercellular spaces. At the end of the first week of culture cell differentiation and extension of processes were evident. A loose neuropil appeared: it was composed by abundant growing neurites and growth cones. Later, the neuropil became more compact and glial processes and synaptic terminals filled with vesicles appeared. The early appearance of vesicles in the synaptic endings was the first evidence of synaptogenesis. Post and presynaptic membrane densities appeared later, and fully mature synaptic contacts were seen by the end of the 3rd week in culture. Scarce myelin sheaths were observed after 35 days in vitro.

A new case for a presynaptic role of dendrites: an immunocytochemical study of the n. raphé dorsalis.

The distribution of serotonin (5-HT) was determined by the application of the preembedding peroxidase-anti-peroxidase (PAP) technique in vibratome and ultrathin sections of the brain stem. The antiserum stained the neuronal groups B1 to B9. Somata, dendrites and axons of multipolar and bipolar neurons were recognized in the usual locations. The most commonly found profiles in the area of the n. raphe dorsalis were dendrites. The search for axon terminals was unsuccessful. The labeled dendrites appear in synaptic contact with unlabeled endings containing round or pleomorphic vesicles, and occasionally some large dense core vesicles. Contacts between two labeled dendrites or processes were not found. Occasionally a dendrodendritic junction between a 5-HT labeled dendrite and an unlabeled dendrite has been found. There are areas of the dendritic membrane free of synaptic junctions and free of glial insulation. Results are discussed in relation with the previously proposed presynaptic role of the dendrites in the neuronal circuitry of the n. raphé dorsalis.

Further evidence for the specificity of anti-5-HT (serotonin)-like antisera in immunocytochemistry. Existence of cyclic secondary amino groups in the immunogen.

The serotonin antigen (5-HT-BSA formaldehyde conjugate) used for obtaining anti-5-HT antibodies was studied to obtain additional data concerning the nature of its immunogen. Dialysis against 0.1 M acetic acid and then against distilled water proved to be the best way of removing 5-HT condensation products not bound to BSA. The hapten has the configuration of a tetrahydro-beta-carboline (THBC) ring structure that is coupled to protein most probably via the carbon(s) ortho to the phenolic hydroxyl group and the indole nitrogen. The cyclic secondary amine of the THBC remained unsubstituted and was not involved in the bridging to BSA. This functional group was effectively blocked by acetylation and was unreactive to glutaraldehyde. On the other hand, in 5-HT conjugates synthesized using glutaraldehyde as the coupling agent, no cyclization to THBC occurred, and the amino groups were blocked. The chemical reactivity of the secondary amino group of the hapten in the synthesized conjugates was compared to the immunoreactivity of 5-HT conjugates formed in tissues. Immunostaining of formaldehyde-fixed serotoninergic neurons of the raphe of rats was suppressed by acetylation and the use of glutaraldehyde as the primary fixative, but the staining was unaffected when glutaraldehyde was reacted with formaldehyde-fixed 5-HT neurons. It is concluded that the cyclic secondary amine of the THBC structure is not conjugated to protein and forms part of the 5-HT-antibody-binding site in immunogens formed in vitro and in tissues.

Basis for the specificity of anti-5-HT-like antisera in immunocytochemistry applied to the central nervous system.

Recently (Pecci Saavedra et al. 1982; Brusco et al. 1982, 1983) we have showed that the actual specificity of the rabbit anti-5-HT antibodies, is for the beta-carboline derivatives of 5-HT as a result of cyclization of the lateral chain. We explained this as resulting from the use of formaldehyde which acted both as a fixative in the preparation of the tissues, and as the coupling agent in the preparation of the immunogen. Following this line we have fixed several brain stem specimens with 0.5% p-benzoquinone; 3% glutaraldehyde; 4% paraformaldehyde plus 0.25% glutaraldehyde and compare the results with tissues fixed in 4% paraformaldehyde. Glutaraldehyde and p-benzoquinone do not produce cyclization of 5-HT but immobilize monoamines in situ. As expected, the antibodies applied according to the PAP technique did not stain the neuronal bodies of the raphe system, known to contain 5-HT when 3-4% glutaraldehyde or 0.5% p-benzoquinone were used. Good staining was obtained with 4% paraformaldehyde alone or with 4% paraformaldehyde plus 0.25% glutaraldehyde. A quantitative assay of the spot test of Larsson (1981) was devised for measuring in vitro the inhibitory effects of 5-HT, of the 5-HT-BSA complex and of the cyclic derivative, 6-OH-1,2,3,4-tetrahydro-beta-carboline. The results confirmed that the avidity of the antiserum is much greater for the cyclic derivatives contained in the 5-HT-BSA complex and for 6-OH-1,2,3,4-tetrahydro-beta-carboline than for 5-HT. It is concluded that the formation of a new ring by the lateral chain of 5-HT is responsible of the in-vitro and in the tissue immunoreactivity of the anti-5-HT-antibodies.

Serotonin-like immunoreactivity and anti-5-hydroxytryptamine (5-HT) antibodies: ultrastructural application in the central nervous system.

Serotonin immunoreactivity of rat neurons was studied using antibodies to 5-hydroxytryptamine (5-HT) raised in rabbits and the peroxidase-antiperoxidase (PAP) technique. The brains were fixed by perfusion with 4% paraformaldehyde + 0.25% glutaraldehyde. Vibratome sections were incubated in 1:1,000 to 25,000 antiserum dilutions. Specificity of 5-HT immunoreactivity was investigated following immunochemical and immunocytochemical criteria. Ultrastructural analysis of the raphe neurons allowed intracellular localization of 5-HT immunoreactivity in somata, dendrites, and synaptic terminals. Granular reaction product deposits were found attached to microtubules, endoplasmic reticulum membranes, synaptic vesicles, and outer mitochondrial membranes. In all cases the reaction product was confined within the limits of the plasma membrane. It is proposed that binding of 5-HT molecules to tissue proteins via a Mannich reaction and formation of intramolecular condensation products (fluorophores) result from aldehyde fixation. The immunogen (5-HT-bovine serum albumin (BSA) complex) exhibits spectrofluorometric emission and excitation maxima similar to those previously described for the 5-HT fluorophore studied in protein films and in fixed tissue. It is concluded that our antibody detects 5-HT-like immunoreactivity preserved in the tissue with the configuration of the fluorophore (i.e., 3,4-dihydrocarboline). Close agreement between the results and previous studies of 5-HT neurons with other techniques (formaldehyde-induced fluorescence, biochemical assays) support the potential value of this antibody.