Role of the Growth Hormone Receptor (GHR) Gene in Skeletal Class II Malocclusion and Its Significant Influence on the Skeletal Facial Profile in Both the Sagittal and Vertical Dimensions: A Systematic Review

This systematic review aims to determine the role of the growth hormone receptor (GHR) gene in skeletal malocclusion and its significant influence on the growth of the maxilla and the mandible in both sagittal and vertical dimensions. A search of the electronic databases of PubMed, Google Scholar, and Cochrane up to and including the year 2023 was made. In addition to this, a hand search of orthodontic and dentofacial orthopaedic journals was carried out. This search included randomized control trials. The Mesh terms used were "skeletal class II malocclusion", "mandibular retrognathism", "sagittal malocclusion", "genetic expression", "genetic factors", "genetic study", "genetic polymorphism", and "single nucleotide polymorphism". The inclusion criteria included studies such as clinical trials and orthopaedic appliances in the presurgical phase. The exclusion criteria for the study were studies not in the English language, case reports, case series, and studies with irrelevant data. It has been cited in various literature that polymorphic variations of the GHR gene could cause variations in mandibular morphogenesis affecting both the mandibular body length and ramal height. However, its effects are quite variable and are based on different population groups. Polymorphism of the GHR gene can be considered a reliable indicator predicting variations in affecting the growth of the mandible with greater significance in affecting the vertical ramal height compared to the body length of the mandible. Its effects on the maxillary skeletal base are rather limited comparatively.

Quantitative assessment of ramal bone width and the proximity of the inferior canal for the predictable insertion of ramal implants: Cone-beam computed tomography study

Objectives:

The study aimed to investigate the optimum level for the placement of ramal implants as a source of anchorage for disimpacting mandibular molars. The criteria in relation to the maximum transverse width of the ramal bone and proximity of the implant to the inferior alveolar canal (IAC) were evaluated using a three-dimensional cone-beam computed tomography scan for predictable placement of ramal implants.

Material and Methods:

The cone-beam computed tomographic scans of 53 untreated patients (aged between 18 and 48 years) were utilized in this study. The maximum transverse width of the ramus and the proximity to the IAC from the site of insertion were measured at six different levels above the central groove of the mandibular first molar. To measure the proximity to the IAC, the mid-point of the maximum transverse width of the ramus was selected as the site of insertion of the implant.

Results:

The maximum and minimum transverse ramal width was 12.48 ± 1.76 mm at 3 mm and 10.42 ± 2.08 mm at 8 mm above the central groove of the permanent mandibular first molar. An average clearance of 9.62 ± 2.59 mm was measured from the site of insertion to the IAC at the different levels evaluated.

Conclusion:

The ramus of the mandible can be a predictable site for implant placement provided the variations in the anatomical structures have been carefully analyzed. It can be concluded that the ramal implants can be safely placed at a level 3–8 mm above the permanent mandibular first molar in relation to the occlusal plane.

Platelet-rich derivatives for accelerating the rate of orthodontic tooth movement - a systematic review and meta-analysis

Objective:

The aim of this systematic review and meta-analysis was to report on the effects of using platelet-rich derivatives on the rate of tooth movement.

Material and Methods:

Both electronic and manual searches were performed with specific eligibility criteria based on population, intervention, comparison, outcome, and study design. Risk of bias (RoB) assessment was done using the Cochrane RoB tool 2, the data were pooled and analyzed using review manager 4.5, and certainty of the evidence was assessed using the Grading of Recommendations Assessment, Development, and Evaluation approach. Two independent reviewers performed the study selection, data extraction, and analysis. Nine studies were included for qualitative analysis and two of them were subjected to meta-analysis.

Results:

The standard mean difference for the rate of canine distal movement with platelet-rich derivatives was not significantly higher than controls at any of the time intervals (P > 0.0001). Rotation of canines, molar mesialization, and pain scores were not affected by the administration of platelet-rich derivatives for accelerating tooth movement. A moderate to high RoB was noted in the included studies and the certainty of the available evidence as assessed by the GRADE approach was moderate.

Conclusion:

The included studies presented with high heterogeneity and more high-quality studies with strict protocols are needed. Even though individual studies report significant acceleration of tooth movement following administration of PR derivatives, moderate certainty of evidence suggests no acceleratory effect on tooth movement.

Efficacy of clear aligners in producing molar distalization: Systematic review

Objectives:

The aim of this review is to systematically analyze the efficacy of molar distalization using clear aligners in non-growing Class II patients.

Materials and Methods:

A complete search across the electronic database through PubMed, Cochrane, Google scholar, LILACS, and manual search of orthodontic journals were done till 2019. Studies were selected on the basis of PRISMA guidelines.

Results:

A total of four articles were included in this review. The amount of molar distalization reported was 2–3 mm.

Conclusion:

Out of the four studies included. In all the studies a significant amount of distalization was reported. Three retrospective studies concluded that distalization with aligners is the most effective of all tooth movements. One study concluded that aligners effectively achieved distalization with an efficacy of 87%, other two studies concluded that aligners effectively distalized the molars with good control over vertical dimension and mesiodistal tipping.

Current overview for chemical disinfection of dental impressions and models based on its criteria of usage: A microbiological study

Objectives

The aims of this study were to compare the efficacy of two proven chemical disinfectants, glutaraldehyde and povidone iodine on dental impression and models by determining the reduction in the microbial load, and to compare changes in the physical properties of the models after adding the disinfectants.

Materials and Methods

Irreversible hydrocolloid upper impressions of 90 patients were made and divided into 3 groups of 30 samples each; Group A--Control group; Impressions were run under clean tap water before pouring the model. Group B--2% Glutaraldehyde sprayed on the impression and left in situ for 10 min before pouring the model. Group C -10 ml of (5%) povidone iodine incorporated into the gypsum before pouring the model. Models from all three groups were subjected to microbiological assessment at three different time intervals, T0--24 h, T1--1 month and T2--3 months of storage by comparing the colony forming units (CFUs) of bacteria and fungi. The compressive strength of 5 models from each group was also analyzed in Newton's/mm².

Results

2% Glutaraldehyde proved more effective than povidone iodine after 24 h of storage (T1), however at the end of 1 month (T1) and 3 months (T2) the Povidone group showed the maximum disinfection. Both the disinfectants caused a reduction in the compressive strength of the model with the povidone iodine group showing the maximum reduction.

Conclusion

Although povidone iodine was the most effective disinfectant after 3 months, it showed a significant reduction in the compressive strength and caused discoloration of the model. 2% Glutaraldehyde proved to be the choice of disinfectant with minimal adverse effects.

Variation in condylar morphology in different malocclusion among Indians

Temporo-mandibular joint (TMJ) joint and the condyle of mandible are observed in the radiographs of the skull and the jaw. Therefore, it is of interest to assess the predictability of four different shapes of condyle in skeletal class I, II and III malocclusion. The four commonly visualized shapes are oval, bird beak, diamond and crooked were assessed using an ortho pantomogram (OPG). Each of the malocclusion was visualized for different shapes of the condyle. 987 OPGs were radiographically evaluated and the morphology of 1974 condylar heads was visualized. The shapes of the condyles were grouped under four different types. Data shows that oval shaped condyle was most common followed by bird beak. There was variability in the diamond and crooked shape and was lesser than the other types. Thus, the shapes of the condyle are useful predictable guide in deciding the nature of the occlusion.

P14.71 An assessment of the reporting and methodological quality of meningioma systematic reviews and meta-analyses

BACKGROUND

Systematic reviews and meta-analyses constitute the highest level of research evidence and for a disease with limited clinical trial activity, are often relied upon to help inform clinical practice. This review of reviews evaluates both the reporting & methodological quality of meningioma evidence syntheses.

MATERIAL AND METHODS

Potentially eligible meningioma reviews published between 1st January 1990 and 31st December 2020 were identified from eight electronic databases. Inclusion required the study to meet the Cochrane guideline definition of a systematic review or meta-analysis. Reviews concerning neurofibromatosis type 2, spinal and pediatric meningiomas were excluded. The reporting and methodological quality of articles were assessed against the following modified guidelines: Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA), A MeaSurement Tool to Assess Systematic Reviews (AMSTAR2) and the Risk of Bias in Systematic Reviews (ROBIS) guidelines.

RESULTS

117 systematic reviews were identified, 57 of which included meta-analysis (48.7%). The number of meningioma systematic reviews published each year has increased with 63 studies (53.9%) published between 01/2018 and 12/2020. A median of 17 studies (IQR 9–29) were included per review. Impact factor of journals publishing a systematic review with or without a meta-analysis was similar (median 2.3 vs 1.8, P=0.397). The mean PRISMA scores for systematic reviews with a meta-analysis was 21.11 (SD 4.1, 78% adherence) and without was 13.89 (SD 3.4, 63% adherence). Twenty-nine systematic reviews with meta-analysis (51%) and 11 without meta-analysis (18%) achieved greater than 80% adherence to PRISMA recommendations. Methodological quality assessment using AMSTAR2 revealed one study (0.9%) as high quality whilst 111 (94.8%) studies were graded as critically low. One hundred and two articles (87.2%) did not utilize a comprehensive search strategy as defined by the AMSTAR2 tool. Ninety-nine studies (84.6%) obtained a high level of concern for potential bias as per the ROBIS assessment. One hundred and eight articles (92.3%) failed to present information that a protocol had been established prior to study commencement and 76 articles (65.0%) did not conduct a risk of bias assessment. Across the three tools, domains relating to the establishment of a protocol prior to review commencement and conducting appropriate risk of bias assessments were frequently low scoring.

CONCLUSION

Overall reporting and methodological quality of meningioma systematic reviews was sub-optimal. Established critical appraisal tools and reporting guidelines should be utilized a priori to assist in producing high-quality systematic reviews.

OS09.7.A Quality of life outcomes in patients with incidental and operated meningiomas: the QUALMS study

BACKGROUND

Long-term Health-Related Quality of Life (HRQoL) is an important measure of patient wellbeing. There is a paucity of studies evaluating HRQoL in meningioma patients.

MATERIAL AND METHODS

Cross-sectional study of adult patients with an incidental or symptomatic intracranial meningioma. Patients with less than 5 years of follow-up, a history of craniospinal radiation or neurofibromatosis type 2 were excluded. HRQoL was evaluated with SF-36, EORTC QLQ-C30 and EORTC QLQ-BN20 questionnaires. Outcome determinants were evaluated using a multi-variable linear regression analysis, adjusted for patient, tumour and treatment characteristics, and duration of follow-up.

RESULTS

699 patients were invited to participate and 246 responded: 118 (48%) had an incidental meningioma. Mean age at diagnosis was 56.8 years (SD=13) and 81% were female. Median time from diagnosis to completion of questionnaire was 8.5 years (IQR 6.8–11.5). During follow-up, 158 patients (64.2%) had at least one operation for their meningioma and 47 patients (19.1%) had radiotherapy. Of those operated, 126 (79.7%) had WHO grade 1 and 24 (15.2%) had grade 2 meningiomas. Compared to normative population values, meningioma patients reported a worse SF-36 general health score (mean 61.9 vs 56.5, P=0.003) but a similar QLQ-C30 global health score (mean 62.3 vs 65.8, P=0.039), worse SF-36 and QLQ-C30 physical functioning scores (mean 74.1 vs 64.6, P<0.001 and mean 81.8 vs 76.5, P=0.007) and similar SF-36 and QLQ-C30 emotional health scores (mean 72.2 vs 70.9, P=0.367 and mean 71.0 vs 71.9, P=0.960). QLQ-C30 cognitive functioning was worse (mean 80.5 vs 71.4, P<0.001). Compared to the meningioma literature, QLQ-BN20 seizure burden was similar (mean 2.0 vs 1.6, P=0.760). A worse performance status at diagnosis was associated with an inferior QLQ-C30 global health score (β-coefficient=-4.9 [95% CI -9.1-(-)0.6] P=0.024). Number of surgeries was significantly associated with a worse QLQ-C30 cognitive functioning score (β-coefficient=-7.0 [95% CI -13.2-(-)0.9], P=0.025). Anti-epileptic drug use was associated with a significantly worse QLQ-C30 emotional health score (β-coefficient=-10.9 [95% CI -21.7-(-)0.01], P=0.050).

CONCLUSION

Meningioma patients have long-term HRQoL impairments affecting their physical and cognitive functions. An understanding that multiple surgeries affects cognitive function, and the need for anti-epileptic drugs equate to poorer emotional health, could help target appropriate therapies and support in the future.

Efficacy of zirconium oxide nanoparticles coated onvstainless steel and nickel titanium wires in orthodontic treatment

It is of particular intrigue to synthesize, analyze anti-bacterial, anti-inflammatory activity, cytotoxicity effect of clove and cardamom reinforced zirconium oxide nanoparticles to coat the orthodontic archwires and study its ramifications. Characterization of nanoparticles was done using Transmission electron microscopic analysis (TEM). Antimicrobial activity was assessed using agar well diffusion method. Cytotoxic effect was assessed using Brine Shrimp Assay. Anti-inflammatory activity was completed using Bovine Serum Albumin (BSA). A Digital magnetic stirrer with a hot plate was used to coat orthodontic arch wires such as NiTi and SS. TEM spherical shape was of size 5 -20 nm. Minimal cytotoxicity was observed at 50 µL. Anti-inflammatory property was fair. Antimicrobial activity against Lactobacillus species, streptococcus mutans staphylococcus aureus and Candida albicans was recorded. NiTi and SS showed a colour shift from silver to orange red with a uniform surface coating on wires. Thus, green synthesized zirconium oxide nanoparticles have potent antimicrobial, anti-inflammatory properties with minimal cytotoxicity for further consideration as nano-coatings on orthodontic archwires such as NiTi and Stainless Steel.

Mini-implant Supported Lip Bumper

Patients with a skeletal class II malocclusion are usually associated with a prognathic maxilla with orthognathic mandible or a retrognathic mandible with orthognathic maxilla or a combination of both. Patients with severe prognathic maxilla are usually associated with increased overjet which results in a lower lip trap. The lip trap should be managed the earliest as it will lead to further proclination of the upper anterior teeth and also hinder the normal growth of the mandible. To overcome the limitations of a conventional lip bumper, we arrived at an idea of fixed lip bumper supported using mini-implants.

Antimicrobial activity of silymarin mediated zinc oxide and hydroxy apatite nanoparticles against oral pathogens

The nanoparticles such as hydroxyapatite, zinc oxide, titanium dioxide and zirconium nanoparticles have application in dentistry. Therefore, it is of interest to document the antimicrobial activity of silymarin mediated zinc oxide and hydroxy apatite nanoparticles against oral pathogens. Hence, we synthesized hydroxyapatie and zinc oxide nanoparticles with silymarin and characterized by UV-visible spectrophotometer. Data shows that silymarin mediated HAP and ZnO nanoparticles have antimicrobial activity against oral pathogens such as Pseudomonas sp, Staphylococcus aureus, Streptococcus mutans, Enterococcus faecalis and Candida albicans.

Primary cardiac myxofibrosarcoma with osteoid differentiation mimicking a left atrial myxoma: A rare entity

Cardiac myxofibrosarcoma (MFS) is an uncommon entity. It is among the most challenging conditions to diagnose due to its rarity, high variability, and non-specific findings. These tumors often simulate left atrial myxoma or mitral stenosis at clinical presentation. Although, the definitive diagnosis of cardiac tumors depends on histopathological examination, various imaging techniques are also useful to study tumor characteristics to plan an appropriate treatment strategy. Here we highlight a case of primary cardiac MFS of left atrium (LA) showing areas of transition to undifferentiated pleomorphic sarcoma (UPS) with bone or osteoid formation, which is extremely rare and not well described. <Learning objective: Primary cardiac myxofibrosarcoma (MFS) is a rare and aggressive cardiac tumor. It is often confused with benign myxoma, leading to a delay in initiation of treatment. This delay can often lead to poor clinical outcomes. Our study will guide clinicians in early diagnosis, treatment, and counseling of patients with this rare entity. Echocardiography, together with magnetic resonance imaging, histology, and immunohistochemistry are essential in the diagnosis of MFS.>.

Facial indices in lateral cephalogram for sex prediction in Chennai population - A semi-novel study

Background:

Osteological examination is a very reliable tool to determine the sex of the individual as the consolidation of the dimorphic characteristics concludes the sex of the individual. This study was performed with lateral cephalograms, which is a vital diagnostic tool for patients undergoing orthodontic treatment. An index was formed, which could be considered as a reliable sex determinant in forensic applications.

Materials and Methods:

This pilot study was performed on samples of the Dravidian population. Two-fifty individuals, whose age ranged between 25 and 40 years, were taken (125 subjects were males and 125 subjects were females). A total of ninety-nine cephalometric variables were compared, subjected to statistical analysis and tested for significance using the t-test.

Results:

Out of a total of 99 variables tested only twenty-four variables showed statistical significance. So, these twenty-four variables were then subjected to discriminant function analysis to evaluate the effectiveness of each variable in predicting the sex of an individual Individually, Ramus length (Ramus ln), Condylion to Gnathion (Co-Gn) and ramus height showed the highest sex determining dependability of 78%. On the flipside, lower anterior facial height (LAFH), with 52%, showed the lowest consistency.

Conclusion:

From this study, it is clearly evident that cephalometric landmarks are reliable sex determinants to a good extent. All the statistically significant measurements, but one, showed acceptable percentages of reliability. This means the chosen variables can be used for the Dravidian population to robustly determine the sex of the individuals of interest.

Mutation in the vasopressin gene eliminates the sex difference in social reinforcement in adolescent rats

The neuropeptide, arginine vasopressin (AVP), is thought to contribute to sex differences in normative and pathological social development by regulating social motivation. Recent studies using Brattleboro rats that have a mutation in the Avp gene, however, have suggested that AVP impacts adolescent social behaviors of males and females in a similar manner through actions on behavioral state (i.e., arousal). In the present study, we made use of a recently developed operant conditioning paradigm to test whether the chronic, lifelong AVP deficiency caused by the Brattleboro mutation impacts the reinforcement value of social stimuli during adolescence. Operant responding for access to a familiar conspecific was assessed in male and female adolescent wild type (WT; normal AVP), heterozygous Brattleboro (HET), and homozygous Brattleboro (HOM) rats. Following the social reinforcement test, rats were tested in the same operant paradigm except that the social reinforcer was replaced with a light reinforcer to determine whether effects of the Brattleboro mutation were specific to social stimuli or a general characteristic of operant conditioning. WT males directed a greater proportion of their responding toward the social and light stimuli than WT females; only males exhibited a preference for these reinforcers over unreinforced ports. The sex difference in social reinforcement was absent in HOM rats, whereas the sex difference in light reinforcement was present in all genotypes. These data indicate that adolescent males are more sensitive to the reinforcing properties of social and light stimuli, and that the sex difference in social, but not light, reinforcement depends upon normal levels of AVP. These findings support the hypothesis that AVP plays a critical role in sex differences in social development by acting on factors that influence social motivation.

Abstract P2-02-09: Breast cancer subtype distribution and circulating tumor DNA in response to neoadjuvant chemotherapy: Experiences from a preoperative cohort within SCAN-B

Introduction: Preoperative chemotherapy in early breast cancer increases the rate of breast preservation and provides prognostic information. In the case of residual disease, a change in subtypes may be observed. Sensitive and reproducible biomarkers predicting treatment response early during the treatment course are needed in order to better exploit the potential benefit of an individualized preoperative treatment.

Material and Methods: In an ongoing prospective study within the population-based SCAN-B project (NCT02306096), patients undergoing preoperative chemotherapy for early or locally recurrent breast cancer have been treated with iv Epirubicin and Cyclophosphamide q3w x 3 in sequence with either Docetaxel q3w x 3 or Paclitaxel q1w x 9 with a preoperative intent. HER2-positive cases also received HER2-directed treatment. At baseline, patients were staged using sentinel node biopsy for clinically node-negative patients and CT scan for cytologically confirmed node-positive cases. A clinical core needle biopsy as well as tissue from the surgical specimen was collected for determination of conventional biomarkers including ER, PgR, HER2 and Ki67. Tumor biopsies for biomolecule-extraction and RNA-sequencing were taken using ultrasound guidance and collected fresh in RNAlater at baseline, after 2 treatment cycles, as well as at surgery. Blood plasma samples were collected at baseline, after one-, three-, and six- 3w treatment cycles, and post-surgery. Using RNA-sequencing data, somatic mutations were identified in the tumor biopsies and personalized analyses for circulating tumor DNA (ctDNA) were performed. A pathological complete remission (pCR) was defined as the complete disappearance of invasive breast cancer in the breast and axilla at time of definitive surgery. Subtyping was performed using modified St Gallen criteria (2013).

Results: Thus far, 45 patients aged 24-74 years have been included, of which 34 (76 %) were clinical stage 2 and 11 (24%) were stage 3. The subtype distribution at baseline was five Luminal A-like (11 %), 21 Luminal B-like (HER2 negative) (47 %), 8 HER2-positive (18 %) and 11 Triple-negative (ductal) (24 %). The rates of pCR in 38 operated cases to date were 0/3 Luminal A-like, 3/19 Luminal B-like (HER2 negative), 2/8 HER2-positive, and 4/7 Triple-negative (overall 24 % pCR rate). One patient did not undergo surgery due to clinically progressive disease. In 25 cases with evaluable residual disease at surgery, there was a shift in the subtype in 13 (52 %), the majority of which represented a transition from Luminal B to Luminal A. No Triple-negative cases underwent a change in subtype during treatment. Results of the ctDNA analyses will be presented at the meeting.

Discussion: We have established an infrastructure allowing for an extensive evaluation of preoperative chemotherapy in early breast cancer. The goal is to develop methods to refine response-guided treatment in early breast cancer using molecular responses in the tumor as well as in the blood circulation. The patients continue to be prospectively monitored with iterative ctDNA analyses during follow-up.

Citation Format: Loman N, Chen Y, Aaltonen K, Brueffer C, George AM, Zander L, Vallon-Christersson J, Häkkinen J, Förnvik D, Rigo R, Ehinger A, Malmberg M, Larsson C, Hegardt C, Borg Å, Rydén L, Saal LH. Breast cancer subtype distribution and circulating tumor DNA in response to neoadjuvant chemotherapy: Experiences from a preoperative cohort within SCAN-B [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P2-02-09.

Targeted sequencing of BRCA1 and BRCA2 across a large unselected breast cancer cohort suggests that one-third of mutations are somatic

We carried out targeted sequencing of BRCA1/2 in an unselected cohort of patients diagnosed with primary breast cancer within a population without strong founder mutations. Eleven percent of cases harbored a germline or somatic BRCA1/2 mutation, and the ratio of germline versus somatic mutation was 2 : 1. This has implications for treatment, genetic counseling, and interpretation of tumor-only testing.

Background

A mutation found in the BRCA1 or BRCA2 gene of a breast tumor could be either germline or somatically acquired. The prevalence of somatic BRCA1/2 mutations and the ratio between somatic and germline BRCA1/2 mutations in unselected breast cancer patients are currently unclear.

Patients and methods

Paired normal and tumor DNA was analyzed for BRCA1/2 mutations by massively parallel sequencing in an unselected cohort of 273 breast cancer patients from south Sweden.

Results

Deleterious germline mutations in BRCA1 (n = 10) or BRCA2 (n = 10) were detected in 20 patients (7%). Deleterious somatic mutations in BRCA1 (n = 4) or BRCA2 (n = 5) were detected in 9 patients (3%). Accordingly, about 1 in 9 breast carcinomas (11%) in our cohort harbor a BRCA1/2 mutation. For each gene, the tumor phenotypes were very similar regardless of the mutation being germline or somatically acquired, whereas the tumor phenotypes differed significantly between wild-type and mutated cases. For age at diagnosis, the patients with somatic BRCA1/2 mutations resembled the wild-type patients (median age at diagnosis, germline BRCA1: 41.5 years; germline BRCA2: 49.5 years; somatic BRCA1/2: 65 years; wild-type BRCA1/2: 62.5 years).

Conclusions

In a population without strong germline founder mutations, the likelihood of a BRCA1/2 mutation found in a breast carcinoma being somatic was ∼1/3 and germline 2/3. This may have implications for treatment and genetic counseling.

Prediction of protective sensory loss, neuropathy and foot ulceration in type 2 diabetes

OBJECTIVES

To prospectively determine clinical and biochemical characteristics associated with the development of peripheral neuropathy, loss of protective sensation, and foot ulceration in persons with type 2 diabetes mellitus (DM) over 7 years.

RESEARCH DESIGN AND METHODS

Graded monofilament (MF) testing, vibration perception threshold, and neuropathy symptom questionnaires were undertaken in 206 participants with type 2 DM without peripheral vascular disease or history of foot ulceration and 71 healthy participants without DM at baseline and after 7 years. 6 monthly glycosylated hemoglobin (HbA1c) levels and annual serum lipid profiles were measured during follow-up of those with DM. Incident foot ulceration was recorded at follow-up.

RESULTS

Taller stature and higher quartiles of serum triglyceride and HbA1c levels were associated with neuropathy at follow-up (p=0.008). Remission of baseline neuropathy was observed in 7 participants at follow-up. 9 participants with type 2 DM developed foot ulcers by the end of the study, only 1 at low risk. Mean HbA1c levels were higher in those who developed foot ulceration (p<0.0001). 1 participant with neuropathy throughout developed a Charcot foot. Failure to perceive 2 or more 2, 4 and 6 g MF stimuli at baseline predicted loss of protective sensation at follow-up.

CONCLUSIONS

Tall stature and worse metabolic control were associated with progression to neuropathy. Mean HbA1c levels were higher in those who developed foot ulcers. Graded MF testing may enrich recruitment to clinical trials and assignation of high risk for foot ulceration.

Effect of various commercially available mouthrinses on shear bond strength of orthodontic metal brackets: an in vitro study

CONTEXT

Alcohol is known to degrade and dissolve the bisphenol A glycidyl methacrylate present in the composite resin. The effect of alcohol containing mouthrinses on the shear bond strength of orthodontic metal brackets bonded with composite resin has not been verified until date and is the purpose of this study.

AIMS

The aims and objectives of the present study were to evaluate (1) Whether there is a significant difference in the shear bond strength of metal orthodontic brackets after the 1 year (12 h) and 2 years simulation (24 h) of mouth rinsing with 4 different commercially available mouthrinses (2 alcoholic and 2 alcohol-free mouthrinses) when compared to the control. (2) Whether alcohol containing mouthrinses have more adverse effect on the shear bond strength when compared with alcohol-free mouthrinses. (3) To assess the site of bond failure using adhesive remnant index.

SETTING AND DESIGN

Experimental - laboratory based.

MATERIALS AND METHODS

A total of 100 upper premolars extracted for orthodontic purpose were collected immediately after extraction, cleared soft-tissue debris and blood and immediately stored in distilled water with 0.1% thymol crystals added to inhibit bacterial growth. Two alcohol containing mouthrinses and two alcohol-free mouthrinses were used and the bonded teeth were placed in the mouthrinses for a stipulated period of time (1 year simulation and 2 years simulation) and shear bond strength were tested using Lloyd Universal Testing Machine.

STATISTICAL ANALYSIS USED

The data were analyzed using analysis of variance and paired samples t-test.

RESULTS

After the 1 year and 2 years simulation time, samples stored in alcohol containing mouthrinses showed lower bond strength (P < 0.05) when compared to samples stored in alcohol free mouthrinses and distilled water (control).

CONCLUSION

Alcohol containing mouthrinses affect the shear bond strength of the metal orthodontic brackets bonded with composite resin (Transbond XT in the present study), more when compared with alcohol-free mouthrinses. It is, therefore, highly advisable to avoid alcohol containing mouthrinses in patients undergoing orthodontic treatment and use alcohol-free mouthrinses as adjuncts to regular oral hygiene procedures for maintaining good enamel integrity and periodontal health, without compromising the shear bond strength of the bonded metal brackets.

Microdeletions in 16p11.2 and 13q31.3 associated with developmental delay and generalized overgrowth

Chromosome microarray analysis of patients with developmental delay has provided evidence of small deletions or duplications associated with this clinical phenotype. In this context, a 7.1- to 8.7-Mb interstitial deletion of chromosome 16 is well documented, but within this interval a rare 200-kb deletion has recently been defined that appears to be associated with obesity, or developmental delay together with overgrowth. We report a patient carrying this rare deletion, who falls into the latter clinical category, but who also carries a second very rare deletion in 13q31.3. It remains unclear if this maternally inherited deletion acts as a second copy number variation leading to pathogenic variation, or is non-causal and the true modifiers are yet to be determined.

Recurrent Transmission of a 17q12 Microdeletion and a Variable Clinical Spectrum

The relatively rare proximal microdeletion of 17q12 (including deletion of the HNF1B gene) is associated with the renal cysts and diabetes syndrome. Recent reports have suggested that there may also be an association between this microdeletion and learning difficulties/autism. This case report describes one of only a few reported families segregating the 17q12 microdeletion, but which highlights the nonpenetrance and variable expressivity of multiple features of this condition.

Chlorhexidine varnishes effectively inhibit Porphyromonas gingivalis and Streptococcus mutans - an in vivo study

Background:

Chlorhexidine varnish (Cervitec- Ivoclar Vivadent- Liechtenstein) is a sustained-release delivery system that can provide protection against white spots and gingivitis, which are common iatrogenic side effects of orthodontic treatment. Chlorhexidine in varnish form does not depend on patient compliance, does not stain teeth or alter taste sensation like the mouth rinse.

Materials and Methods:

A split-mouth technique was followed in the treatment of 30 patients selected by stringent selection criteria, evaluating a single application of the test varnish on two randomly allotted quadrants along with a placebo on the other two quadrants. Streptococcus mutans counts responsible for white spots and P. gingivalis count [using PCR test] responsible for gingivitis were done at the start of the study, and then 1 and 3 months later.

Results:

The chlorhexidine varnish reduced the Streptococci mutans count at the end of 1 month, and this reduction was statistically significant. At the end of 3 months, there was no difference in the S. mutans counts between the two groups. There was a statistically significant reduction in the P. gingivalis count at the end of both 1 and 3 months in comparison to the placebo group.

Conclusion:

Chlorhexidine varnishes are capable of reducing S. mutans and P. gingivalis and gingivitis, thus improving the overall oral health of the patient. The side effects of chlorhexidine mouth rinses are not seen with this varnish. An application schedule of at least once a month is recommended as the effectiveness is reduced comparatively at the end of 3 months.

Clinical trial: renzapride therapy for constipation-predominant irritable bowel syndrome--multicentre, randomized, placebo-controlled, double-blind study in primary healthcare setting

BACKGROUND

Relatively few pharmacological treatment options are available for treating patients with irritable bowel syndrome. New and effective medicines are urgently required.

AIM

To identify an appropriate dosage of renzapride (a 5-HT(4) receptor full agonist/5-HT(3) receptor antagonist) to treat abdominal pain/discomfort in patients with constipation-predominant irritable bowel syndrome.

METHODS

In this randomized, placebo-controlled, phase IIb study in the primary care setting, men and women were randomized to placebo or renzapride (1, 2 or 4 mg/day) for 12 weeks. The primary outcome measure was patient self-assessed relief of abdominal pain/discomfort during weeks 5-12. Secondary efficacy measures included patients' assessment of their bowel habits, stool consistency and quality of life.

RESULTS

Although there were no statistically significant differences between renzapride and placebo for relief from abdominal pain/discomfort, responder rates in the renzapride treatment groups increased dose dependently, with the 4 mg/day group being consistently numerically greater than placebo. Importantly, a larger numerical treatment difference vs. placebo was observed in women (8% and 12% respectively). Statistically significant improvements in bowel movement frequency and stool consistency were observed in the 4 mg/day group relative to placebo. Renzapride was well tolerated at all doses.

CONCLUSIONS

This study confirms the gastrointestinal prokinetic effects of renzparide. The data also suggested a potentially beneficial effect on abdominal pain/discomfort in women with constipation-predominant irritable bowel syndrome.

Dissociation of water on defective carbon substrates

Using calculations from first principles, we found that water can dissociate over defective sites in graphene or nanotubes following many possible reaction pathways, some of which have activation barriers lower than half the value for the dissociation of bulk water. This reduction is caused by spin selection rules that allow the system to remain on the same spin surface throughout the reaction.

Multidrug resistance in parasites: ABC transporters, P-glycoproteins and molecular modelling

Parasitic diseases, caused by protozoa, helminths and arthropods, rank among the most important problems in human and veterinary medicine, and in agriculture, leading to debilitating sicknesses and loss of life. In the absence of vaccines and with the general failure of vector eradication programs, drugs are the main line of defence, but the newest drugs are being tracked by the emergence of resistance in parasites, sharing ominous parallels with multidrug resistance in bacterial pathogens. Any of a number of mechanisms will elicit a drug resistance phenotype in parasites, including: active efflux, reduced uptake, target modification, drug modification, drug sequestration, by-pass shunting, or substrate competition. The role of ABC transporters in parasitic multidrug resistance mechanisms is being subjected to more scrutiny, due in part to the established roles of certain ABC transporters in human diseases, and also to an increasing portfolio of ABC transporters from parasite genome sequencing projects. For example, over 100 ABC transporters have been identified in the Escherichia coli genome, but to date only about 65 in all parasitic genomes. Long established laboratory investigations are now being assisted by molecular biology, bioinformatics, and computational modelling, and it is in these areas that the role of ABC transporters in parasitic multidrug resistance mechanisms may be defined and put in perspective with that of other proteins. We discuss ABC transporters in parasites, and conclude with an example of molecular modelling that identifies a new interaction between the structural domains of a parasite P-glycoprotein.

The ABC transporter structure and mechanism: perspectives on recent research

ATP-binding cassette (ABC) transporters are multidomain integral membrane proteins that utilise the energy of ATP hydrolysis to translocate solutes across cellular membranes in all phyla. ABC transporters form one of the largest of all protein families and are central to many important biomedical phenomena, including resistance of cancers and pathogenic microbes to drugs. Elucidation of the structure and mechanism of ABC transporters is essential to the rational design of agents to control their function. While a wealth of high-resolution structures of ABC proteins have been produced in recent years, many fundamental questions regarding the protein's mechanism remain unanswered. In this review, we examine the recent structural data concerning ABC transporters and related proteins in the light of other experimental and theoretical data, and discuss these data in relation to current ideas concerning the transporters' molecular mechanism.

Effects of atomic short-range order on the properties of perovskite alloys in their morphotropic phase boundary

The effects of atomic short-range order on the properties of Pb(Zr(1-x)Ti(x))O3 alloy in its morphotropic phase boundary (MPB) are predicted by combining first-principles-based methods and annealing techniques. Clustering is found to lead to a compositional expansion of this boundary, while the association of unlike atoms yields a contraction of this region. Atomic short-range order can thus drastically affect properties of perovskite alloys in their MPB, by inducing phase transitions. Microscopic mechanisms responsible for these effects are revealed and discussed.

Anomalous properties in ferroelectrics induced by atomic ordering

Complex insulating perovskite alloys are of considerable technological interest because of their large dielectric and piezoelectric responses. Examples of such alloys include (Ba1-xSrx)TiO3, which has emerged as a leading candidate dielectric material for the memory-cell capacitors in dynamic random access memories; and Pb(Zr1-xTix)O3 (PZT), which is widely used in transducers and actuators. The rich variety of structural phases that these alloys can exhibit, and the challenge of relating their anomalous properties to the microscopic structure, make them attractive from a fundamental point of view. Theoretical investigations of modifications to the atomic ordering of these alloys suggest the existence of further unexpected structural properties and hold promise for the development of new functional materials with improved electromechanical properties. Here we report ab initio calculations that show that a certain class of atomic rearrangement should lead simultaneously to large electromechanical responses and to unusual structural phases in a given class of perovskite alloys. Our simulations also reveal the microscopic mechanism responsible for these anomalies.

Symmetry and structure in P-glycoprotein and ABC transporters what goes around comes around

The ABC superfamily of membrane transporters is one of the largest classes of proteins across all species and one of the most intensely researched. ABC proteins are involved in the trafficking of a diverse variety of biological molecules across cell membranes, with some members implicated in medical syndromes such as cystic fibrosis and multidrug resistance to anti-cancer drugs. In the absence of X-ray crystallographic data, structural information has come from spectroscopy, electron microscopy, secondary structure prediction algorithms and residue substitution, epitope labelling and cysteine cross-linking studies. These have generally supported a model for the topology of the transmembrane domains of ABC transporters in which a single aqueous pore is formed by a toroidal ring of 12 alpha helices, deployed in two arcs of six helices each. Although this so-called 6 + 6 helix model can be arranged in either mirror or rotational symmetry configurations, experimental data supports the former. In this review, we put forward arguments against both configurations of this 6 + 6 helix model, based on what is known generally about symmetry relationships in proteins. We relate these arguments to P-glycoprotein, in particular, and discuss alternative models for the structure of ABC transporters in the light of the most recent research.

A dengue outbreak among camp participants in a Caribbean island, 1995

BACKGROUND

Dengue, a mosquito-transmitted viral disease, is a risk for visitors in tropical and subtropical areas. Several participants in a community-assistance program in Tortola, British Virgin Islands, in August, 1995, reported dengue-like symptoms either before or soon after leaving the island.

METHODS

We conducted a retrospective cohort study to determine the extent of the outbreak, risk factors for illness, and the proportion of inapparent infections. Program participants were interviewed by telephone or mail, and asked to submit a serum sample for dengue diagnosis. A clinically-diagnosed case of dengue was defined as a person with fever and two or more of the following: headache, retro-orbital pain, myalgia, arthralgia, rash, or hemorrhagic manifestations. Serum specimens were tested for virus isolation, polymerase chain reaction (PCR), plaque-reduction neutralization (PRNT) or anti-dengue IgM and IgG antibody.

RESULTS

Thirty-two (97%) of the 33 program participants responded; 21 of the 32 (66%) provided at least one serum sample for study. The median age was 17 years; 20 (62%) were women. Of 32 respondents, 22 (69%) met the clinical case definition for dengue: 15 of them (68%) had a positive IgM antibody response and 7 did not submit a serum sample. Dengue 1 virus (DEN-1) was identified by PCR in one case and all 11 positive PRNT results. No asymptomatic infections were identified. No respondent used effective mosquito repellent, and only 2 (6%) used bednets.

CONCLUSIONS

A DEN-1 outbreak with a high attack rate (69%) occurred in a group of young short-term community aid workers. There were no asymptomatic infections documented. Participants' rare use of bednets or effective mosquito repellent highlights the importance of providing travelers to tropical areas with information about dengue fever and the recommended precautions to protect against infection.

Subunit interactions in ABC transporters: towards a functional architecture

The ABC superfamily is a diverse group of integral membrane proteins involved in the ATP-dependent transport of solutes across biological membranes in both prokaryotes and eukaryotes. Although ABC transporters have been studied for over 30 years, very little is known about the mechanism by which the energy of ATP hydrolysis is used to transport substrate across the membrane. The recent report of the high resolution crystal structure of HisP, the nucleotide-binding subunit of the histidine permease complex of Salmonella typhimurium, represents a significant breakthrough toward the elucidation of the mechanism of solute translocation by ABC transporters. In this review, we use data from the crystallographic structures of HisP and other nucleotide-binding proteins, combined with sequence analysis of a subset of atypical ABC transporters, to argue a new model for the dimerisation of the nucleotide-binding domains that embraces the notion that the C motif from one subunit forms part of the ATP-binding site in the opposite subunit. We incorporate this dimerisation of the ATP-binding domains into our recently reported beta-barrel model for P-glycoprotein and present a general model for the cooperative interaction of the two nucleotide-binding domains and the translocation of mechanical energy to the transmembrane domains in ABC transporters.

DNA probes specific for Aeromonas hydrophila (HG1)

Aeromonas hydrophila (HG1)-specific RAPD-PCR fragments were investigated for their potential as DNA probes. From 20 RAPD-PCR fragment bands, it was found that two were specific to all isolates of Aeromonas hydrophila (HG1) tested. Cloning and nucleotide sequence determination of one of these bands showed that co-migration of similar sized amplicons had occurred and that this band (designated '7e') contained at least four fragments of different sequences. Three of these individual amplicons had a sequence specific to Aer. hydrophila (HG1) isolates. The sequence of one of these amplicons ('7e5') was used to design primers for a specific polymerase chain reaction (PCR). The specificity of the PCR was achieved using a modified hot-start procedure. The identity of the PCR amplicons was confirmed by high stringency hybridization with a digoxygenin-labelled 7e5 probe.

A new structural model for P-glycoprotein

Multidrug resistance to anti-cancer drugs is a major medical problem. Resistance is manifested largely by the product of the human MDR1 gene, P-glycoprotein, an ABC transporter that is an integral membrane protein of 1280 amino acids arranged into two homologous halves, each comprising 6 putative transmembrane alpha-helices and an ATP binding domain. Despite the plethora of data from site-directed, scanning and domain replacement mutagenesis, epitope mapping and photoaffinity labeling, a clear structural model for P-glycoprotein remains largely elusive. In this report, we propose a new model for P-glycoprotein that is supported by the vast body of previous data. The model comprises 2 membrane-embedded 16-strand beta-barrels, attached by short loops to two 6-helix bundles beneath each barrel. Each ATP binding domain contributes 2 beta-strands and 1 alpha-helix to the structure. This model, together with an analysis of the amino acid sequence alignment of P-glycoprotein isoforms, is used to delineate drug binding and translocation sites. We show that the locations of these sites are consistent with mutational, kinetic and labeling data.

Co-migration of RAPD-PCR amplicons from Aeromonas hydrophila

Random amplified polymorphic DNA polymerase chain reaction (RAPD-PCR) uses arbitrary primers and low stringency annealing conditions to amplify anonymous DNA fragments which are then depicted in agarose gels. RAPD-PCR fingerprints have been used for typing and differentiation of bacteria and, increasingly, for the study of genetic relationships between strains and species of microorganisms, plants and animals. The analysis of such fingerprints is based upon the assumption that co-migration of amplicons does not occur and that any given band contains a single amplicon. This report shows that co-migration of fragments of nearly identical size, but different nucleotide sequences, occurs between different isolates and within single RAPD-PCR bands from Aeromonas hydrophila. The possibility of the same phenomenon occurring for other prokaryotic or eukaryotic genomes argues for caution in the interpretation of RAPD-PCR fingerprints.

23Na chemical shifts and local structure in crystalline, glassy, and molten sodium borates and germanates

A simple correlation between average Na-O bond length and 23Na isotropic chemical shift in crystalline germanates and borates has been established, similar to existing correlations for sodium in silicates and carbonates. This empirical trend is discussed in terms of a decreasing paramagnetic contribution to the chemical shift with increasing average bond length. The correlation is then applied to data for sodium borate and germanate glasses and melts from room temperature to 1200 degrees C, where both structural and compositional effects on the chemical shift are apparent.

The XRCC2 DNA repair gene: identification of a positional candidate

The human XRCC2 gene, complementing a hamster cell line (irs1) hypersensitive to DNA-damaging agents, was previously mapped to chromosome 7q36.1. Following radiation reduction of human/hamster hybrids, the gene was found to be associated with the marker D7S483. Yeast artificial chromosomes (YACs) carrying D7S483 were fused to the irs1 cell line to identify a YAC that complemented the sensitivity defect. Transcribed sequences were isolated by direct cDNA selection using the complementing YAC, and these were mapped back to the YAC and hybrids to define a 400-kb region carrying XRCC2. Sequencing of cDNAs led to the identification of both known and novel gene sequences, including a candidate for XRCC2 with homology to the yeast RAD51 gene involved in the recombinational repair of DNA damage. Strong support for the candidacy of this gene was obtained from its refined map position and by the full complementation of irs1 sensitivity with a 40-kb cosmid carrying the gene.

Functional expression of the human MDR1 gene in Escherichia coli

In this preliminary study, we report the cloning of the human MDR1 cDNA into a prokaryotic expression vector and the consequent functional expression of heterologous P-glycoprotein in Escherichia coli. We demonstrate increased resistance to the P-glycoprotein substrates TPA+, TPP+, and puromycin; reduced accumulation of TPP+ and tetracycline by resistant cells; and the expression of a full-length immunoreactive P-glycoprotein molecule in the membrane fraction of resistant cells. The obvious structural and functional similarities of P-gp to prokaryotic ABC transporters and other efflux transporters argues for a more complete study of the consequences pertaining to the expression of human P-glycoprotein in E. coli.

Multidrug resistance in enteric and other gram-negative bacteria

In Gram-negative bacteria, multidrug resistance is a term that is used to describe mechanisms of resistance by chromosomal genes that are activated by induction or mutation caused by the stress of exposure to antibiotics in natural and clinical environments. Unlike plasmid-borne resistance genes, there is no alteration or degradation of drugs or need for genetic transfer. Exposure to a single drug leads to cross-resistance to many other structurally and functionally unrelated drugs. The only mechanism identified for multidrug resistance in bacteria is drug efflux by membrane transporters, even though many of these transporters remain to be identified. The enteric bacteria exhibit mostly complex multidrug resistance systems which are often regulated by operons or regulons. The purpose of this review is to survey molecular mechanisms of multidrug resistance in enteric and other Gram-negative bacteria, and to speculate on the origins and natural physiological functions of the genes involved.