Crystal structure of the protein kinase domain of yeast AMP-activated protein kinase Snf1

AMP-activated protein kinase (AMPK) is a master metabolic regulator, and is an important target for drug development against diabetes, obesity, and other diseases. AMPK is a hetero-trimeric enzyme, with a catalytic (alpha) subunit, and two regulatory (beta and gamma) subunits. Here we report the crystal structure at 2.2A resolution of the protein kinase domain (KD) of the catalytic subunit of yeast AMPK (commonly known as SNF1). The Snf1-KD structure shares strong similarity to other protein kinases, with a small N-terminal lobe and a large C-terminal lobe. Two negative surface patches in the structure may be important for the recognition of the substrates of this kinase.

Informed consent in oral health care

BACKGROUND

Informed consent and autonomy are the major ethical principles that define the relationship between health workers and the patient. A patient should be given adequate information on the risks and benefits of treatment to be undertaken and also alternative treatment options.

OBJECTIVES

To investigate what and how much information dental patients perceived to had been given by oral health workers about treatment, benefits, risks and management alternatives in order to take decisions and give informed consent about their treatment.

DESIGN

Cross sectional descriptive survey.

SETTING

The study was conducted at Ann Latsky Nursing College, Johannesburg.

SUBJECTS

The sample size consisted of 173 student nurses in their first, second and third years of training. Only students who had treatment in the previous three years were included in the study.

RESULTS

The majority of the students were treated in the private sector (85.0%) by male oral health workers (61.6%) and dentists (89.5%) as opposed to dental therapists or oral hygienists. The study indicated that the majority of the respondents (75.6%) were given information about the treatment to be undertaken. The information appeared to have pertained to costs, pain, chances of success and duration of treatment. One hundred (74.07%) gave verbal consent and (16.30%) gave both verbal and written consent. Only 37.79% of the respondents were told of alternative options available, 47.17% of the benefits, and 38.6% of the risks of treatment.

CONCLUSION

These findings have ethical implications for oral health workers. There is an urgent need to sensitise oral health workers on the specifics of informed consent.

Dental caries in six, 12 and 15 year old Venda children in South Africa

BACKGROUND

Oral diseases is still a major problem in most developing countries. Within the Republic of South Africa, there remains areas where few or no studies have been done on the oral health status. The emerging district health system with decentralisation of health services to address past inequity in health care in South Africa also provides compelling case for data collection at regional levels.

OBJECTIVES

To assess the prevalence and severity of dental caries of school children; determine the caries patterns of the study population and to provide useful data for the planning of oral health services in this region.

DESIGN

Descriptive analytical study.

SETTING

School children in the Donald Fraser Health District, Venda in the Northern province, Republic of South Africa.

SUBJECTS/METHODS

A total of 519 school children in the age groups 6, 12 and 15 years were examined by a calibrated examiner for dental caries using WHO diagnostic criteria. Both the schools, which were divided into rural and peri-urban locations and the children that participated were randomly selected.

RESULTS

A mean dmft(sd) of 2.68(3.29) in six year olds and a mean DMFT (sd) scores of 0.61(1.50) and 1.26 (2.18) were recorded in the 12 and 15 year olds respectively. In the six year olds the upper anterior teeth showed highest susceptibility to caries, clearly indicating that black children suffer from early infant caries. At ages of 12 and 15 the mandibular molars were the teeth most affected. The decayed component constituted the main part of the dmft and DMFT scores. Ninety-nine percent of these lesions were untreated and the restorative care was almost nil.

CONCLUSION

An important finding was the doubling of the mean DMFT from the 12-year-olds to 15-year olds and the caries levels for all age groups was higher than the provincial average. The treatment required were mostly extractions and simple fillings, the majority of which could be managed by dental auxiliaries using the Atraumatic Restorative Treatment Technique. This study indicates that preventive oral health measures should be implemented on the younger age groups in order to control dental caries.

Minimal intervention dentistry (MI) for South Africa

The intention of Minimal Intervention Dentistry (MI) is to preserve as much tooth tissue as possible and to offer less threatening care to fearful patients. MI is based on a new understanding of cariology and the therapeutic value of biomimetic materials such as Glass lonomers. It has particular relevance to a new caries classification and employs treatment concepts such as selective caries removal and sealed restorations. The MI approach is appropriate for the vast majority of the population in South Africa; it addresses the public fear of dental treatment. It can be an effective private practice builder and is thus applicable to private and public services.

Oral health knowledge and original practices of African traditional healers in Zonkizizwe and Dube, South Africa

Self reported oral health knowledge and practices of 83 traditional healers in Zonkizizwe (56) and Dube (27) Gauteng Province, South Africa were carried out using a questionnaire and clinical photographs of common oral conditions. The mean age for the total group was 49.5 with 35 males and 48 females. Although only 17 of the healers were members of a professional association, many indicated their willingness to join one. 40 (71%) of healers in Zonkizizwe kept written client records but far fewer 3 (11%) did so in Dube. More than 90% of traditional healers from both areas correctly identified photographs of gingival inflammation, dental caries and oral candidiasis. Over 50% of healers from both areas had patients who presented with mouth problems. Ninety percent of healers in Zonkizizwe referred patients to the formal health care sector but less than 50% in Dube did so. A vast majority of healers gave oral health advice to their patients, many of whom gave specific tooth brush instruction. The study provides an initial understanding of the practices of healers regarding oral health.

From didactic teaching to participatory learning. An innovative approach

A course in Public Oral Health is currently offered by the Division of Public Oral Health (POH) to students in their final (6th year) of study for the degree of Bachelor of Dental Science. A fundamental aspect of this project was to shift the teaching methods from didactic to a participatory, student-centred approach, based on current local and international trends in medical, dental and general education. In 1999 the course covering core Public Health topics was presented over a period of 20 weeks to 49 students who were divided into three groups. Staff members were trained in participatory, student-centred teaching methods. An evaluation of students and staff was conducted at the end of the course. Results show that students were satisfied with the teaching methods employed and commended the Division on the organisation of the course. Students were unhappy with the amount of reading required in preparation for weekly seminars. They felt that the course was inappropriately positioned in their final year of study, due to pressure of achieving quotas for the clinical courses. Nevertheless, the main objectives of the Public Oral Health course were achieved through the adoption of a participatory, student-centred teaching approach.

The 1.2 A structure of the human sulfite oxidase cytochrome b(5) domain

The molybdenum- and iron-containing enzyme sulfite oxidase catalyzes the physiologically vital oxidation of sulfite to sulfate. Sulfite oxidase contains three domains: an N-terminal cytochrome b(5) domain, a central domain harboring the molybdenum cofactor (Moco) and a C-terminal dimerization domain. Oxidation of the substrate sulfite is coupled to the transfer of two electrons to the molybdenum cofactor. Subsequently, these electrons are passed on, one at a time, to the b(5) heme of sulfite oxidase and from there to the soluble electron carrier cytochrome c. The crystal structure of the oxidized human sulfite oxidase cytochrome b(5) domain has been determined at 1.2 A resolution and has been refined to a crystallographic R factor of 0.107 (R(free) = 0.137). A comparison of this structure with other b(5)-type cytochromes reveals distinct structural features present in the sulfite oxidase b(5) domain which promote optimal electron transport between the Moco of sulfite oxidase and the heme of cytochrome c.

Structural studies of molybdopterin synthase provide insights into its catalytic mechanism

Molybdenum cofactor biosynthesis is an evolutionarily conserved pathway present in eubacteria, archaea, and eukaryotes, including humans. Genetic deficiencies of enzymes involved in cofactor biosynthesis in humans lead to a severe and usually fatal disease. The molybdenum cofactor contains a tricyclic pyranopterin, termed molybdopterin, that bears the cis-dithiolene group responsible for molybdenum ligation. The dithiolene group of molybdopterin is generated by molybdopterin synthase, which consists of a large (MoaE) and small (MoaD) subunit. The crystal structure of molybdopterin synthase revealed a heterotetrameric enzyme in which the C terminus of each MoaD subunit is deeply inserted into a MoaE subunit to form the active site. In the activated form of the enzyme, the MoaD C terminus is present as a thiocarboxylate. The present study identified the position of the thiocarboxylate sulfur by exploiting the anomalous signal originating from the sulfur atom. The structure of molybdopterin synthase in a novel crystal form revealed a binding pocket for the terminal phosphate of molybdopterin, the product of the enzyme, and suggested a binding site for the pterin moiety present in precursor Z and molybdopterin. Finally, the crystal structure of the MoaE homodimer provides insights into the conformational changes accompanying binding of the MoaD subunit.

Policies and protocols for preventing transmission of HIV infection in oral health care in South Africa

Human immunodeficiency virus (HIV) infection constitutes an unparalleled public health challenge. The unique nature of most oral health procedures, instrumentation and patient-care settings requires specific strategies and protocols aimed at preventing the transmission of HIV/AIDS between oral health care providers and patients, as well as between patients themselves. The present study investigated the level of information and training about protocols and policies for preventing the transmission of HIV/AIDS in oral health care settings in South Africa. The data collection techniques utilised available information, in-depth interviews and an open-ended questionnaire. The respondents were 20 purposively selected key informants who were senior officers for HIV/AIDS programmes and/or oral health organisations. Sixteen (80%) of the respondents reported that there were no existing oral health policies on HIV/AIDS in their health care institutions or organisations. None of the interviewees knew of any specific protocols on HIV/AIDS in the oral health care setting that emanated from South Africa. In addition, none of the dental professional associations had established an infection control committee or a support system for members who might become infected with HIV and develop AIDS. Territorial boundaries existed between sectors within the medical disciplines, as well as between the medical and oral health disciplines. Numerous general impediments were identified, such as prejudice, denial and fear, inadequate training and/or information about the infection, lack of representation and resources for policy planning, a lack of interest from the business sector, and approaching HIV/AIDS in the workplace as a 'one-time issue' Other obstacles identified included unemployment, poverty, illiteracy, disempowerment of women and inadequate communication of policies to service providers. Additional issues raised included the migrant labour systeM, complexities of language and culture, the large unstructured sex industry, high prevalence of sexually transmitted infections and lack of funding. All of these have an impact on oral health. Future policy directions identified included 'increasing access to HIV information and postexposure prophylaxis' 'shift towards care and support for those living with HIV/AIDS with emphasis on community and home-based care' and 'improving intersectoral co-ordination and collaboration'. The study demonstrated gaps in availability and access to policies and protocols on HIV/AIDS by managers and health workers. Specific strategic recommendations are made for oral health.

Stereoselectivity of enoyl-CoA hydratase results from preferential activation of one of two bound substrate conformers

Enoyl-CoA hydratase catalyzes the hydration of trans-2-crotonyl-CoA to 3(S)- and 3(R)-hydroxybutyryl-CoA with a stereoselectivity (3(S)/3(R)) of 400,000 to 1. Importantly, Raman spectroscopy reveals that both the s-cis and s-trans conformers of the substrate analog hexadienoyl-CoA are bound to the enzyme, but that only the s-cis conformer is polarized. This selective polarization is an example of ground state strain, indicating the existence of catalytically relevant ground state destabilization arising from the selective complementarity of the enzyme toward the transition state rather than the ground state. Consequently, the stereoselectivity of the enzyme-catalyzed reaction results from the selective activation of one of two bound substrate conformers rather than from selective binding of a single conformer. These findings have important implications for inhibitor design and the role of ground state interactions in enzyme catalysis.

Undergraduate training in the atraumatic restorative treatment (ART) approach--an activity report

The Division of Public Oral Health at the University of the Witwatersrand conducted a 2-week ART training course for 5th year dental students in the School of Oral Health Sciences. Students were taught both theoretical knowledge and clinical skills in ART. Course evaluation showed that the course achieved its aims and objectives and was considered a worthwhile experience by students. However, there were some limitations to the format of the programme. We recommend that ART should be integrated as part of clinical student training in the BDS curriculum.

Implementation of the ART approach in South Africa: an activity report

The Atraumatic Restorative Treatment (ART) approach has been adopted in public dental services in South Africa as an appropriate and economical means to provide basic restorative care in communities where it was not possible before. The approach also offers a less-traumatic treatment concept for fearful patients and children in the private dental practice. In 2000, the Division of Community Dentistry, University of the Witwatersrand, implemented a training, research and service programme in the ART approach. The aim of these activities was the promotion of ART at various levels within the oral health care system in the Republic of South Africa. The objectives of the programme were to initiate and provide training of oral health workers in ART, to evaluate the outcome of training and service programmes and to disseminate results. This paper describes the Division's ART activities in 2000, regarding public, private and refugee health services.

Structure-Based design, synthesis and sAR of a novel series of thiopheneamidine urokinase plasminogen activator inhibitors

The serine protease urokinase plasminogen activator (uPA) is thought to play a central role in tumor metastasis and angiogenesis. Molecular modeling studies suggest that 5-thiomethylthiopheneamidine inhibits uPA by binding at the S1 pocket of the active site. Further structure based elaboration of this residue resulted in a novel class of potent and selective inhibitors of uPA.

Synthesis of thiophene-2-carboxamidines containing 2-aminothiazoles and their biological evaluation as urokinase inhibitors

The serine protease urokinase (uPa) has been implicated in the progression of both breast and prostate cancer. Utilizing structure based design, the synthesis of a series of substituted 4-[2-amino-1,3-thiazolyl]-thiophene-2-carboxamidines is described. Further optimization of this series by substitution of the terminal amine yielded urokinase inhibitors with excellent activities.

Crystal structure of molybdopterin synthase and its evolutionary relationship to ubiquitin activation

Molybdenum cofactor (Moco) biosynthesis is an evolutionarily conserved pathway present in eubacteria, archaea and eukaryotes, including humans. Genetic deficiencies of enzymes involved in Moco biosynthesis in humans lead to a severe and usually fatal disease. Moco contains a tricyclic pyranopterin, termed molybdopterin (MPT), that bears the cis-dithiolene group responsible for molybdenum ligation. The dithiolene group of MPT is generated by MPT synthase, which consists of a large and small subunits. The 1.45 A resolution crystal structure of MPT synthase reveals a heterotetrameric protein in which the C-terminus of each small subunit is inserted into a large subunit to form the active site. In the activated form of the enzyme this C-terminus is present as a thiocarboxylate. In the structure of a covalent complex of MPT synthase, an isopeptide bond is present between the C-terminus of the small subunit and a Lys side chain in the large subunit. The strong structural similarity between the small subunit of MPT synthase and ubiquitin provides evidence for the evolutionary antecedence of the Moco biosynthetic pathway to the ubiquitin dependent protein degradation pathway.

Clinical evaluation of the ART approach and materials in peri-urban farm schools of the Johannesburg area

In this study, 1,325 school children from 7 farm schools were examined. Their mean age (+/- SD) was 10.5 +/- 3.0 (range 6-11) years. At baseline, the mean DMFT score was 1.1 +/- 1.7 and 36.4% of the children had caries. The prevalence of fluorosis among the children was 12.6%. Curative treatment was offered to all the children. A total of 113 children (8.5%) with one-surface cavities on permanent teeth and without fluorosis were treated using the atraumatic restorative treatment (ART) approach. A total number of 163 cavities were included in the study, of which 82 were treated with Fuji IX glass-ionomer cement and 81 with Ketac-MOLAR (hand mix). One year after treatment, restoration and sealant parts of ART fillings were examined. Caries status was also determined. The placing of the ART fillings and their evaluation were performed by different practitioners. A total number of 108 restorations (58 with Fuji IX, 50 with Ketac-MOLAR) were evaluated. Results of ART fillings showed a survival rate of 93.1% with Fuji and 94.0% with Ketac-MOLAR. Retention of the sealant parts of ART fillings was observed in 81% of restorations with Fuji IX and 76% with Ketac-MOLAR, not connected to the filled cavity. Caries was absent on all teeth restored with Fuji IX and noted in only one tooth restored with Ketac-MOLAR, not connected to the filled cavity. The retention rate after a 12-month period was acceptable and ART approach proved to be an appropriate technique for restoring teeth in this population group. There were no statistically significant differences between the survival rates of the two glass-ionomer restorative materials (P > 0.05).

Oral health status in an institutionalised elderly Jewish population

The oral health status and treatment needs of 95 institutionalised elderly Jewish persons were determined. The mean DMFT was 23.4, with the M component increasing with age. Untreated carious lesions were identified in men and women of all ages. A relatively small percentage (10.5%) of subjects were affected by root caries. In 75% of cases of identified periodontal disease, the condition presented as bleeding or calculus. All subjects were in need of oral hygiene instruction and 64 (67.3%) required scaling and root planing. Complex treatment formed only a small percentage of the overall treatment needs. A low prevalence of temporomandibular joint problems, denture stomatitis and angular cheilitis was noted. A relatively high prevalence of untreated oral disease of low severity was observed, indicating the need for a comprehensive form of preventive and basic oral care.

Managed health care and dentists in the Gauteng province

Managed health care (MHC) has emerged in South Africa as an alternative system to control the cost of health care. Fears, negative perceptions and much uncertainty have surrounded this issue since its introduction in South Africa. The purpose of this study was to assess the understanding, perceptions and opinions of dentists residing in the Gauteng province about the emergence, benefits, impact, and future of MHC in South Africa. Eighty-six dentists (21.5%) out of the sample population of 400 responded to the questionnaire. The majority (66.7%) of the respondents perceived MHC to be a threat to their practices, with most feeling that MHC will interfere with the doctor-patient relationship. Forty-two per cent of the respondents were of the opinion that MHC will not succeed in South Africa. The results suggest that this sample of dentists do not consider MHC to be an alternative to the existing fee-for-service system. The introduction of MHC in South Africa is mostly based on models used in the USA, which might not be appropriate in the unique South African environment.

HIV infection and oral health care in South Africa

This study determined the knowledge, attitude and practice of oral health care workers in public clinics in South Africa towards HIV/AIDS and investigated the implementation of infection control measures. A total of 727 questionnaires were distributed to dentists, dental therapists, oral hygienists and chairside assistants in the public dental clinics of 9 provinces, of which 276 were returned from 8 provinces, giving a response rate of 38%. The questionnaire covered demographic factors and assessed issues such as knowledge, infection control practices, continuing education, legal, ethical and psychosocial issues and available support for HIV/AIDS. The common oral manifestations seen by respondents were candidiasis, acute necrotising ulcerative gingivitis (ANUG), hairy leukoplakia and Kaposi's sarcoma. Of the 174 who had a previous HIV test, 48% were for insurance purposes and 21% for post-needle-stick injury. Over 10% of the respondents indicated that gloves were not available at all, that there was an inadequate supply of water, and that there was no autoclave in their clinic. Nearly 50% of the clinicians had not had hepatitis B vaccination in the last 3 years. Fifteen respondents (5.4%) were not willing to treat HIV-positive patients. Only 48% had access to a written post-exposure management protocol and post-exposure medication was available to only 36.6%. The vast majority of the respondents clearly expressed a need for additional education on HIV/AIDS. The study demonstrated a need to add knowledge, enhance personal skills and improve the application of universal precautions.

An oral health promotion module for the primary health care nursing course in Acornhoek, South Africa

The severe personnel shortage in the health professions in most developing communities is well documented. This dearth of health workers and the widespread adoption of the primary health care approach (PHCA), requires that health professionals be trained to understand and effectively utilize the skills offered by other disciplines in the health care field. Nurses are expected to play active roles in the promotion of health including oral health, particularly in the rural under-served communities. There is a paucity of oral health education in nursing curricula. This article describes a 4-day module on oral health promotion developed and delivered to 36 nurses as part of a 12-month primary health care nursing (PHCN) training course. The module utilized a variety of educational methods and materials to facilitate and encourage both individual and group learning. The module was evaluated using both student academic attainment and perceptions as outcome measures. The evaluation and the experience of facilitating this module show that an oral health promotion module of short duration can sensitize nurses to the importance of oral health and increase oral health knowledge and skills.

Oral health care--the perceptions and self-reported practices of nurses

A structured, 40-item, self-administered questionnaire was distributed to 290 nurses attending an international health care conference held in Pretoria, South Africa. The questionnaire focused on; personal and demographic details of the respondents, history of dental disease and dental attendance, exposure to oral health during and after basic nurse training, opinions on oral health and the nursing curriculum, perceptions on the relationship between nurses and oral health personnel, perceived ability to promote oral health and self-reported contributions to oral health. The 153 respondents were predominantly female (140, 93.3%) with a mean age (+/- Standard deviation) of 43.0 +/- 7.5 years. One hundred and twenty one (79.1%) had previously visited a dental clinic for personal care and 105 (68.6%) had suffered from dental disease, dental pain, bleeding gums or bad breadth. Only 71 (46.4%) were exposed to experiences in assessing and caring for clients with oral disease during their training. Significant positive correlation were found between exposure (during training) to experiences in assessing and caring for clients with oral diseases and some factors. One hundred and forty-eight (96.7%) agreed oral health should be integrated into the nursing curriculum. Forty-one (26.8%) indicated they have not been contributing to the oral health of their clients or community while 92 (60.1%) described their personal contributions as fair. One hundred and thirty six respondents (88.9%) wished to be able to do more for their clients in the area of oral health.

The impact of the ART approach on the treatment profile in a mobile dental system (MDS) in South Africa

The changing profile of oral care rendered through the Mobile Dental System (MDS), after the introduction of the Atraumatic Restorative Treatment (ART) approach is described. During the first year of introduction of ART, the percentages of amalgam restorations and tooth extractions decreased significantly (P < 0.0001). This is partly ascribed to a change in choice of treatment by dental operators in favour of ART and also due to an increase in acceptance by patients because of the reduced fear, and the patient-friendly nature of the ART approach. The reduction in amalgam restorations was 16.0 per cent for permanent and 1.4 per cent for primary posterior teeth. Extraction of posterior teeth was reduced by 17.4 per cent in the permanent and 35.7 per cent in the primary dentitions. The restorative component of oral care increased by 33.4 per cent in the permanent and 37.1 per cent in primary posterior teeth. The one-year survival of one-surface ART restorations using Fuji IX and KetacMolar was 93.6 per cent. Full and partial (more than 90 per cent) retention of the sealant part of the ART restoration was obtained in 75 per cent of the cases after one-year. During the one-year period, infection control was made more simple and this facilitated easier maintenance of mobile dental equipment. The introduction of the ART approach reduced extraction, restored more teeth and made oral care in the MDS more preventive, less threatening and thus more patient-friendly.

Oral health among Liberian refugees in Ghana

OBJECTIVE

To promote community involvement in the provision of oral health services.

DESIGN

The project consisted of a four-week training course in oral health for selected refugees, an oral health survey based on WHO guidelines and conducted by the refugees themselves and the provision of oral health care services to the community by the trained refugees.

SETTING

Liberian refugee camp, Gomoa Buduburam in Ghana.

SUBJECTS

Liberian refugees of all ages.

INTERVENTIONS

Twelve refugees were given short term training in oral health. In the oral health survey, 196 refugees were clinically examined for dental caries, periodontal disease and malocclusion.

MAIN OUTCOME MEASURES

DMFT (for dental caries), CPITN (for periodontal disease), and malocclusion scores for selected subjects. Also clinical services rendered.

RESULTS

Oral health survey revealed a mean age (+/- SD) of 25.7 (+/- 9.5) years. Only thirty nine (19.9%) of the subjects were caries-free, and total DMFT was 2.5 +/- 2.2. Based on the CPITN, 107 (54.6%) required oral hygiene instructions (OHI), and 41 (20.9%) required prophylactic scaling with OHI. Forty four (22.5%) of the subjects had normal occlusion and 152 (77.5%) mild to severe malocclusion. Periodontal (75.5%), prosthetic (52.5%) interventions and extractions (34.2%) constituted the bulk of the treatment needs required. Clinical treatment was rendered by the trained refugees to 846 patients over a twelve month period.

CONCLUSION

Relief programmes for refugees should emphasise a primary health care approach, focusing on prevention, based on appropriate technology, and promoting involvement by the refugee community in the provision of services.

Utilisation of oral health services, oral health needs and oral health status in a peri-urban informal settlement

Interviews were conducted with 294 black residents (155 females and 138 males) of a peri-urban informal settlement in Gauteng to ascertain utilisation of oral health services, oral health needs and oral health status. Only 37 per cent of the sample had consulted a dentist or medical practitioner, usually for extractions. Teenagers and employed persons were significantly less likely to utilise dentists than the older age groups and unemployed persons. Forty per cent were currently experiencing oral health problems such as a sore mouth, tooth decay and bleeding/painful gums. Two hundred and twelve (73 per cent) interviewees wanted dental treatment or advice. Residents who rated their oral health status as fair or poor appeared to have the greatest need for oral health services. The use of interviews appears to be a cost-effective method of determining oral morbidity.