Establishment of CT diagnostic reference levels (DRLs) for a Singapore healthcare cluster.

INTRODUCTION: The use of computed tomography (CT) in healthcare institutions has increased rapidly in recent years. The Singapore Health Services (SingHealth) cluster of healthcare institutions has taken the first step in establishing a local cluster-wide CT Diagnostic Reference Levels (DRL) in Singapore. CT dose data from each institution were collected through two primary dosimetry metrics: volume CT dose index (CTDIvol measured in mGy) and dose-length product (DLP measured in mGy.cm). METHODS: Data from 19 CT scanners in seven institutions under one of Singapore healthcare cluster were retrospectively collected and analysed. The five common adult CT examinations analysed were CT Brain (non-contrast enhanced), CT Chest (IV contrast enhanced), CT Kidney-Ureter-Bladder (CT KUB, non-contrast enhanced), CT Pulmonary Angiogram (CT PA, IV contrast enhanced) and CT Abdomen-Pelvis (CT AP, IV contrast enhanced, single phase). Median CTDIvol and DLP values for the five CT examinations from each institution were derived, with the cluster DRLs determined as the 75th percentile of the distribution of the institution median dose values. RESULTS: A total of 2413 dose data points were collected over a six-month period from June to November 2020. The cluster CT DRLs for the five CT examinations were determined to be 47 mGy and 820 mGy.cm for CT Brain, 5.4 mGy and 225 mGy.cm for CT Chest, 6.7 mGy and 248 mGy.cm for CT PA, 4.6 mGy and 190 mGy.cm for CT KUB and 6.9 mGy and 349 mGy.cm for CT AP. CONCLUSION: The establishment of the cluster CT DRLs provided individual institutions with a better understanding if their CT doses are unusually high or low, while emphasising that these DRLs are not meant as hard dose limits or constraints to follow strictly.

Mutations in LAMB2 causing a severe form of synaptic congenital myasthenic syndrome.

BACKGROUND: We describe a severe form of congenital myasthenic syndrome (CMS) associated with congenital nephrosis and ocular malformations caused by two truncating mutations in the gene encoding the laminin beta2 subunit (LAMB2). METHODS AND RESULTS: Mutational analysis in the affected patient, who has a history of a serious untoward reaction to treatment with acetylcholinesterase inhibition, revealed two frame-shifting heteroallelic mutations, a maternally inherited 1478delG and a paternally inherited 4804delC. An anconeus muscle biopsy demonstrated a profound distortion of the architecture and function of the neuromuscular junction, which was strikingly similar to that seen in mice lacking laminin beta2 subunit. The findings included: pronounced reduction of the axon terminal size with encasement of the nerve endings by Schwann cells, severe widening of the primary synaptic cleft and invasion of the synaptic space by the processes of Schwann cells, and moderate simplification of postsynaptic folds and intact expression of the endplate acetylcholinesterase. The endplate potential quantal content was notably reduced, while the frequencies and amplitudes of miniature endplate potentials were only moderately diminished and the decay phases of miniature endplate potentials were normal. Western blot analysis of muscle and kidney tissue and immunohistochemistry of kidney tissue showed no laminin beta2 expression. CONCLUSION: This case, which represents a new type of synaptic CMS, exemplifies the wide variability of phenotypes associated with LAMB2 mutations and underscores the fundamental role that laminin beta2 plays in the development of the human neuromuscular junction.

Routine chest radiography in uncomplicated suspected acute coronary syndrome rarely yields significant pathology.

AIM: To determine the prevalence and nature of chest radiographic abnormalities in patients presenting to the emergency department (ED) with suspected acute coronary syndrome but without signs or symptoms of other pathology. METHODS: A retrospective study was undertaken of patients presenting to a tertiary referral ED between July 2005 and June 2006. Inclusion criteria were age > or = 18 years and suspected acute coronary syndrome (as defined). Exclusion criteria were any signs or symptoms consistent with other cardio/pulmonary pathology (as defined). The study end points were the proportion of patients who had a chest radiograph, the proportion who had an abnormal chest radiograph, the nature of the abnormality and whether the radiograph changed management. RESULTS: Of 158 patients who met the entrance criteria, 130 (82.2%, 95% CI 75.2% to 87.7%) underwent chest radiography. In 40 patients (30.8%, 95% CI 23.1% to 39.6%) an abnormality was reported by the radiologist, although most were of no consequence (eg, previous sternotomy). In three patients there was documented evidence that the chest radiograph altered management (one was treated for pulmonary oedema, one for pneumonia and one was investigated further for suspicious hilar nodes). In a further two patients (one with middle lobe collapse and consolidation and one with pulmonary oedema) the chest radiograph may have changed management, although this was not documented. CONCLUSION: In the patient group examined, chest radiography resulted in a low yield of unexpected chest pathology. Routine chest radiography for this group is questionable and needs further investigation.

Surface finish of resin-modified and highly viscous glass ionomer cements produced by new one-step systems.

This study investigated the surface finish of resin-modified (Fuji II LC, GC) and highly viscous (Fuji IX GP Fast, GC) glass ionomer cements after treatment with three one-step finishing/polishing systems (One-Gloss [OG], Shofu; Pogo [PG], Dentsply; Sof-Lex Brush [SB], 3M-ESPE). The surface roughness obtained was compared to that using a matrix strip [MS], a two-step rubber abrasive (CompoSite [CS], Shofu) and a graded abrasive disk (Super Snap [SS], Shofu) system. Eight specimens (3-mm long x 3-mm wide x 2-mm deep) of each material were made for the various treatment groups. With the exception of the MS group, all groups were roughened with 320 grit grinding paper using a lapping device prior to finishing/polishing with the different systems. The mean surface roughness (microm) was measured with a profilometer. Data was subjected to ANOVA/Scheffe's tests at significance level 0.05. Mean Ra ranged from 0.13 to 1.04 microm for Fuji II LC and 0.14 to 0.81 for Fuji IX GP. For both materials, the smoothest surface was obtained with MS and the roughest with OG. Depending on the materials, the surface finish produced by PG and SB was superior or comparable to that obtained with CS and SS. The effectiveness of one-step systems, when used to finish/polish resin-modified and highly viscous glass ionomer cements, is product dependent.

Comparison of surface finish of new aesthetic restorative materials.

This study compared the surface finish of eight different types of aesthetic restorative materials. The materials included resin-modified (Fuji II LC [FL], GC) and highly viscous (Fuji IX GP Fast [FN], GC) glass ionomer cements, a compomer (F2000 [FT], 3M-ESPE), minifilled (Z100 [ZO], 3M-ESPE) and microfilled (A110 [AO], 3M-ESPE) composites and materials based on recently introduced ormocer (Admira [AM], Voco), nanomer (Filtek Supreme Translucent [FST], 3M-ESPE) and nanocluster technology (Filtek Supreme [FS], 3M-ESPE). Sixteen specimens (3-mm long x 3-mm wide x 2-mm deep) of each material were divided into two equal groups. Specimens in Group 1 received no further treatment after polymerization against a matrix strip, while the specimens in Group 2 were roughened with 320 grit grinding paper using a lapping device and were finished/polished with a graded abrasive disk system (Super-Snap, Shofu). The mean roughness (Ra, microm) of materials was determined using a surface profilometry. Data was analyzed by ANOVA/Scheffe's test at significance level 0.05. Mean Ra values ranged from 0.04 to 0.16 microm for Group 1 specimens and 0.15 to 0.68 microm for Group 2 specimens. Results of statistical analysis were as follows: Group 1-FS, FST, FL, FN, AM > FT, AO, ZO; Group 2-FN, FT, FL > AO, FS, ZO, AM, FST (> indicates significantly greater Ra values). For the finished/polished composite materials, Ra values observed for AM and FST were significantly lower than for AO and FS. The surface finish of glass ionomers and compomer was significantly poorer than composites. Composite materials based on ormocer and nanomer technology were significantly smoother than those based on microfillers and nanoclusters.

Finishing/polishing of composite and compomer restoratives: effectiveness of one-step systems.

This study investigated the surface texture of composite (Z100, 3M ESPE) and compomer (F2000, 3M ESPE) restoratives after treatment with different one-step finishing/polishing systems (One-Gloss [OG], Shofu; PoGo [PG], Dentsply; Sof-Lex Brush [SB], 3M ESPE). The surface roughness obtained was compared to that using a matrix strip [MS], a two-step rubber abrasive (CompoSite [CS], Shofu) and a graded abrasive disk (Super Snap [SS], Shofu) system. Eight specimens (3-mm long x 3-mm wide x 2-mm deep) of each material were made according to manufacturer's instructions. With exception of the MS group, all groups were roughened with 320 grit grinding paper using a lapping device prior to finishing/polishing with the different systems. The mean surface roughness (microm) was measured with a profilometer. Data was subjected to ANOVA/Scheffe's tests and independent samples t-test at significance level 0.05. Mean Ra ranged from 0.22 to 0.32 microm for Z100 and 0.45 to 0.68 for F2000. For both materials, the smoothest surfaces were obtained with MS. The roughest surfaces were observed after treatment with SS and OG for Z100 and F2000, respectively. The effectiveness of the finishing/polishing systems was material dependent. The surface finish produced by PG and SB was superior or comparable to that obtained with CS, SS and OG.

Children's and parents' attitudes towards dentists' appearance, child dental experience and their relationship with dental anxiety.

AIM: To evaluate child and parental attitudes towards dentists' appearance, subsequently related to a child's dental experience and their association with child's anxiety levels. METHODS: 402 parent-child pairs were surveyed using interviewer-administered questionnaires at the School Dental Service, Health Promotion Board, Singapore. Standardised pictures of models with different attires, ages, genders and ethnicities were shown to the parent-child pairs. Information on each child's dental experience was obtained. Parental proxy was used to evaluate the children's dental fear levels based on the Children's Fear Survey Schedule-Dental Subscale (CFSS-DS). RESULTS: Personal protective equipment (PPE) was the attire of choice for both parents and children, followed by the paediatric coat. Formal and informal attire was least preferred by children and parents, respectively. Parents preferred female dentists to treat their child, whereas children preferred a dentist of the same gender (p < 0.001). Parent's and child's preferences for the child's dentist's appearance were shown to be significantly different (p < 0.001). CFSS-DS scores were also significantly associated with the number of previous dental visits (p = 0.002) as well as a history of extractions (p = 0.02), but not with child's demographics, dmft or preference for dentist's appearance (p > 0.05). CONCLUSION: Regardless of child anxiety levels, the PPE followed by paediatric coats were preferred over other choices of dentists' attire. Children tended to choose a dentist who was of a younger age, and of the same gender and ethnicity as themselves. Parents tended to choose younger, female dentists of the same ethnicity as themselves. Subjective experience of extractions, as well as multiple dental visits appeared to play a more significant role in the development of dental fear than dental caries experience per se.

An examination of HIV/AIDS patients who have excellent adherence to HAART.

This paper examines the attitudes and beliefs of HIV/AIDS patients with excellent adherence to highly active antiretroviral therapy (HAART) and how they differ from those with suboptimal adherence. Forty-four persons with HIV/AIDS, 28 men and 16 women, participated in a qualitative semi-structured interview which was based on the Health Belief Model. The main outcomes were themes consistent with several dimensions of this model, reflecting differences in the health-related attitudes and beliefs of the excellent adherers compared to the suboptimal adherers. Patients with excellent adherence voiced the following themes when compared to less adherent patients: (1) believed adherence rates needed to be 90-100% for medication efficacy; (2) trusted their primary providers greatly; (3) took medications even when actively using substances of abuse; (4) were open about their HIV status and received substantial social support; (5) cited staying healthy as their key motivator; (6) were not actively depressed; all had normal CESD scores. Our study suggests that patients with excellent adherence to HAART differ from their less adherent counterparts in terms of key health-related attitudes and beliefs. Identifying and studying excellent adherers provides new insights and strategies for enhancing adherence to HAART.