Machine learning-based ABA treatment recommendation and personalization for autism spectrum disorder: an exploratory study

Autism spectrum is a brain development condition that impairs an individual's capacity to communicate socially and manifests through strict routines and obsessive-compulsive behavior. Applied behavior analysis (ABA) is the gold-standard treatment for autism spectrum disorder (ASD). However, as the number of ASD cases increases, there is a substantial shortage of licensed ABA practitioners, limiting the timely formulation, revision, and implementation of treatment plans and goals. Additionally, the subjectivity of the clinician and a lack of data-driven decision-making affect treatment quality. We address these obstacles by applying two machine learning algorithms to recommend and personalize ABA treatment goals for 29 study participants with ASD. The patient similarity and collaborative filtering methods predicted ABA treatment with an average accuracy of 81-84%, with a normalized discounted cumulative gain of 79-81% (NDCG) compared to clinician-prepared ABA treatment recommendations. Additionally, we assess the two models' treatment efficacy (TE) by measuring the percentage of recommended treatment goals mastered by the study participants. The proposed treatment recommendation and personalization strategy are generalizable to other intervention methods in addition to ABA and for other brain disorders. This study was registered as a clinical trial on November 5, 2020 with trial registration number CTRI/2020/11/028933.

Assessment of an ensemble of machine learning models toward abnormality detection in chest radiographs

Respiratory diseases account for a significant proportion of deaths and disabilities across the world. Chest X-ray (CXR) analysis remains a common diagnostic imaging modality for confirming intra-thoracic cardiopulmonary abnormalities. However, there remains an acute shortage of expert radiologists, particularly in under-resourced settings, resulting in severe interpretation delays. These issues can be mitigated by a computer-aided diagnostic (CADx) system to supplement decision-making and improve throughput while preserving and possibly improving the standard-of-care. Systems reported in the literature or popular media use handcrafted features and/or data-driven algorithms like deep learning (DL) to learn underlying data distributions. The remarkable success of convolutional neural networks (CNN) toward image recognition tasks has made them a promising choice for automated medical image analyses. However, CNNs suffer from high variance and may overfit due to their sensitivity to training data fluctuations. Ensemble learning helps to reduce this variance by combining predictions of multiple learning algorithms to construct complex, non-linear functions and improve robustness and generalization. This study aims to construct and assess the performance of an ensemble of machine learning (ML) models applied to the challenge of classifying normal and abnormal CXRs and significantly reducing the diagnostic load of radiologists and primary-care physicians.

A novel stacked generalization of models for improved TB detection in chest radiographs

Chest x-ray (CXR) analysis is a common part of the protocol for confirming active pulmonary Tuberculosis (TB). However, many TB endemic regions are severely resource constrained in radiological services impairing timely detection and treatment. Computer-aided diagnosis (CADx) tools can supplement decision-making while simultaneously addressing the gap in expert radiological interpretation during mobile field screening. These tools use hand-engineered and/or convolutional neural networks (CNN) computed image features. CNN, a class of deep learning (DL) models, has gained research prominence in visual recognition. It has been shown that Ensemble learning has an inherent advantage of constructing non-linear decision making functions and improve visual recognition. We create a stacking of classifiers with hand-engineered and CNN features toward improving TB detection in CXRs. The results obtained are highly promising and superior to the state-of-the-art.

B-24 Objective and Subjective Sleep Measures are Associated with Neurocognition in Middle-Aged and Older Adults With and Without HIV

Objective

Poorer sleep quality is related to worse cognitive functioning in the general population and people living with HIV; however, many studies use self-report sleep questionnaires that rely on retrospective recall. This study aimed to examine the relationship between objective (wrist actigraphy) and subjective sleep quality with neurocognitive functioning.

Method

Eighty-five adults aged 50-74 years with and without HIV (HIV+ n = 53, HIV- n = 32) were recruited from the community and ongoing studies at UC San Diego. Participants completed comprehensive neuropsychological testing assessing global and domain-specific cognition. Participants wore actigraphy watches for 14 nights after neuropsychological testing to objectively assess sleep quality (i.e., total sleep time (TST), efficiency, wake after sleep onset, and sleep fragmentation). The Pittsburgh Sleep Quality Index assessed subjective sleep quality.

Results

After adjusting for demographic variables and use of sleep medications, there were no differences in any sleep quality measures by HIV status (p’s>0.05). In separate adjusted linear regression models, lower sleep efficiency (p = 0.02; 95% CI: -9.5, -1.1) and greater sleep fragmentation (p = 0.02; 95% CI: -0.82, -0.09) were associated with worse learning. Less TST was associated with worse working memory (p = 0.02; 95% CI: -9.2, -0.8). In contrast, worse subjective sleep quality was associated with worse executive function (p < 0.01; 95% CI: -1.18, -0.23) and working memory (p = 0.03; 95% CI: -1.22, -0.07).

Conclusion

Both objective and subjective sleep quality were associated with cognition in both persons with and without HIV; however, subjective and objective sleep quality were associated with different cognitive domains. Therefore, both objective and subjective sleep quality are important health behaviors to assess.

C-25 Neurocognitive Correlates of Chronological and Subjective Age Differences in Persons Living with HIV compared to those without HIV

Objective

Investigate the discrepancy between subjective and chronologic age by HIV-serostatus, and the association of this discrepancy with subjective neurocognitive functioning (NCF) and objective NCF.

Methods

One hundred nineteen persons living with HIV (PWLH) and 98 HIV-uninfected (HIV-) adults (Mage = 50.9; SDage = 7.9) completed a comprehensive neurobehavioral battery. Subjective age was assessed using a single-item question (i.e., “how old do you feel?”). The difference between chronologic and subjective age resulted in subjective age discrepancy scores (SADS). Subjective NCF was measured using the Patient’s Assessment of Own Functioning Inventory; objective NCF was measured using global demographically-corrected T-scores. Linear regressions examined the association between subjective and objective NCF with SADS, covarying for significant PLWH and HIV- group differences (i.e., education, sex, ethnicity, and lifetime Major Depressive Disorder).

Results

PLWH reported lower SADS (indicating closer correspondence between chronologic and subjective age) than their HIV- counterparts, who reported feeling much younger (p = .05; 95% CI: -5.4, .001). Among PLWH, better subjective NCF was significantly related to greater SADS (p = .0002; 95% CI: -.48, -.16). Objective NCF was not associated with SADS among persons with and without HIV.

Conclusions

Adults without HIV reported feeling younger than their chronologic age, whereas PLWH felt significantly closer to their chronologic age. SADS were negatively associated with only subjective NCF, among only PLWH. This suggests perceived cognitive functioning has a greater impact on psychological well-being among this group. Future research is warranted to delineate the relationship between HIV, subjective neurocognition, and psychosocial factors related to daily functioning to improve successful aging outcomes among this vulnerable population.

A prospective genome-wide study of prostate cancer metastases reveals association of wnt pathway activation and increased cell cycle proliferation with primary resistance to abiraterone acetate-prednisone

Background

Genomic aberrations have been identified in metastatic castration-resistant prostate cancer (mCRPC), but molecular predictors of resistance to abiraterone acetate/prednisone (AA/P) treatment are not known.

Patients and methods

In a prospective clinical trial, mCRPC patients underwent whole-exome sequencing (n = 82) and RNA sequencing (n = 75) of metastatic biopsies before initiating AA/P with the objective of identifying genomic alterations associated with resistance to AA/P. Primary resistance was determined at 12 weeks of treatment using criteria for progression that included serum prostate-specific antigen measurement, bone and computerized tomography imaging and symptom assessments. Acquired resistance was determined using the end point of time to treatment change (TTTC), defined as time from enrollment until change in treatment from progressive disease. Associations of genomic and transcriptomic alterations with primary resistance were determined using logistic regression, Fisher's exact test, single and multivariate analyses. Cox regression models were utilized for determining association of genomic and transcriptomic alterations with TTTC.

Results

At 12 weeks, 32 patients in the cohort had progressed (nonresponders). Median study follow-up was 32.1 months by which time 58 patients had switched treatments due to progression. Median TTTC was 10.1 months (interquartile range: 4.4-24.1). Genes in the Wnt/β-catenin pathway were more frequently mutated and negative regulators of Wnt/β-catenin signaling were more frequently deleted or displayed reduced mRNA expression in nonresponders. Additionally, mRNA expression of cell cycle regulatory genes was increased in nonresponders. In multivariate models, increased cell cycle proliferation scores (≥ 50) were associated with shorter TTTC (hazard ratio = 2.11, 95% confidence interval: 1.17-3.80; P = 0.01).

Conclusions

Wnt/β-catenin pathway activation and increased cell cycle progression scores can serve as molecular markers for predicting resistance to AA/P therapy.

The Role of “Liquid Biopsy” Repositories in Cancer Care in Low to Middle–Income Countries

Background and context: Translation of underlying individual genomic heterogeneity in cancer into precision medicine practice requires annotated cancer biorepositories. The potential for practice of precise medicine is also coupled to saving vital resources in low to middle–income countries. An overview of experience and outcomes from a tertiary level cancer center in a high-income country for liquid biobank established since 2009 is presented. Aim: To understand the challenges of building economically viable biorepositories that can be used for molecular diagnostics while delivering cancer care. Strategy/Tactics: An institutional ethics–approved prospective liquid biorepository was established in September of 2009 for advanced cancer patients. Informed consent–approved collection of 29.5 mL blood/urine was performed serially on enrolled patients and clinical annotation was obtained during follow-up including previous, current and future treatments and their outcomes. All specimens were processed using a uniform protocol in which extraction of germline DNA from buffy coats; serum for proteomics; platelet-poor and platelet-rich plasma (in citrate and EDTA anticoagulants) for microRNA and cell-free DNA extractions; and extraction of PAXgene RNA/DNA from whole blood was performed. Processing was done within 45 minutes of sample acquisition and storage in −80°C freezers with no freeze–thaw cycles. Program/Policy process: Biobanking for cancer care. Outcomes: Between September of 2009 and January of 2015, 535 advanced-stage prostate cancer patients in hormone-sensitive and castrate-resistant stage; 250 advanced kidney cancer patients; 110 testicular cancer patients were enrolled and 1550 collections were performed serially. This generated >60,000 plasma/serum/DNA/RNA aliquots. Nucleic acids (DNA/RNA) from buffy coats and whole blood of 500-1000 ng volume each were also extracted. Cell-free DNA for somatic mutational and copy number analysis; single nucleotide profiling from germline DNA; RNA expression profiling from whole blood and microRNA analysis in plasma has been performed from this cohort along with proteomics using tandem mass spectrometry. By 2017, this has resulted in >35 scientific publications; 5 patents; multiple national and international grant awards and enhanced precision cancer care for patient care. The cost burden for establishing the infrastructure was highly economical. What was learned: In our experience, liquid biopsy repositories can augment clinical cancer globally, but do not find this discussed in low to middle–income nations. Advancing and applying molecular oncology and team science to prospectively collected and retrospectively annotated biobanks can be a cost-efficient resource in a global cancer healthcare delivery system and a useful tool for scientific and economic opportunities and collaborations.

Bilateral clavicular attachment of omohyoid muscle

Omohyoid muscle present in cervical region is of particular importance to anatomists as it defines anteriorly the carotid triangle and divides the posterior cervical triangle. It has superior and inferior bellies and an intermediate common tendon. Like sternohyoid, sternothyroid and thyrohyoid muscles, omohyoid is also an infrahyoid muscle, but it differs from them in its course. The infrahyoid muscles are formed from a muscle primordium occurring in the anterior cervical area. Anderson (Anderson, 1881) theorized that the superior belly of the omohyoid muscle is a true infrahyoid muscle, whereas the inferior belly most likely shares a common embryology with the subclavius muscle. In the present study, during routine dissection in the neck region of an adult male cadaver of 50 years age, an anomalous origin of inferior belly of omohyoid with absence of intermediate tendon was observed bilaterally. It was arising from clavicle on both sides. Both the muscle bellies were measured from the lateral end of fascial sling. The inferior belly of omohyoid extending from the lateral margin of sling to clavicular surface was measured 3.3cm in length on left side and 3.6cm on right side. The omohyoid is important in neck dissections because it is considered as an ideal landmark for level III and IV lymph node metastases. Knowledge of variations of this muscle is very important for surgeries in neck region because of its close relation to the internal jugular vein and brachial plexus. Its crucial relationship to vascular structures in the neck makes it an important landmark during neck surgeries.

Pronator teres accessorius: A new variant in flexor antebrachial musculature

Muscles of flexor compartment of forearm have a common origin from medial epicondyle of humerus. Additional bellies of flexor muscles are commonly reported but presence of supernumerary muscles is an infrequent phenomenon. The present study describes an unusual muscle mass in flexor compartment of forearm simulating pronator teres. During routine dissection the upper limb of a 50 years old male cadaver, a supernumerary muscle was found on left side of the upper limb in the flexor compartment. The origin of the muscle was 2cm wide and aponeurotic in nature and attached to an oblique line extending from the inferior surface of the medial epicondyle and the medial surface of the trochlea. It was inserted on an oblique line 2.5cm wide on the radius in area between supinator superiorly and flexor digitorum profundus inferiorly. Existence of accessory muscles, which connect flexor muscles, could be explained embryologically by incomplete cleavage of flexor mass during development. The flexor muscles of the forearm develop from the flexor mass which subsequently divides into two layers: superficial and deep. The deep layer gives rise to flexor digitorum superficialis, flexor digitorum profundus and flexor pollicis longus. These supernumerary muscles are extremely rare entities and probably represent deranged embryological development or the process of atavism in which the anomalous part persist for a longer time in the tree of evolution.

Identification of hepatic microvascular adhesion-related genes of human colon cancer cells using random homozygous gene perturbation

Random homozygous gene perturbation (RHGP), in combination with liver sinusoidal endothelial cell (LSEC) adhesion screening of clonal colon cancer cells with perturbed genes, was used to identify genes contributing to the hepatic microvascular adhesion of colon cancer cells. Plasmid vector encoding transactivator and gene search vector were transfected into HT-29 human colorectal cancer cells to create a HT-29 RHGP cell library; the adhesion of these library cells to primary cultured mouse LSEC significantly decreased in the presence of RSL1 ligand (inducer), indicating that most of the genes contributing to HT-29 adhesion to LSEC were altered. Next, HT-29 RHGP cell library fractions with upregulated or silenced LSEC adhesion-related genes were isolated. Around 160 clones having altered expression in LSEC adhesion-related genes were obtained, and nine relevant protein-coding genes were identified. Some were proadhesive genes detected because of their overexpression in adherent HT-29 cells (DGCR8 and EFEMP1 genes) and their silenced status in nonadherent HT-29 cells (DGKE, DPY19L1, KIAA0753, PVR and USP11 genes). Others were antiadhesive genes detected because of their overexpression in nonadherent HT-29 cells (ITPKC gene) and their silenced status in adherent HT-29 cells (PPP6R2 gene). Silencing of PVR, DGCR8 and EFEMP1 genes decreased adhesion to LSEC and hepatic microvascular retention of HT-29 cells. The results conclude that RHGP was a valuable strategy for the discovery of mechanisms regulating microvascular adhesion of circulating colon cancer cells before hepatic metastasis formation. Identified genes may contribute to understand the metastatic process of colon cancer and to discovering molecular targets for hepatic metastasis therapeutics.

Is suppression of apoptosis a new therapeutic target in sepsis?

Sepsis remains as a leading cause of death in critically ill patients. Unfortunately, there have been very few successful specific therapeutic agents that can significantly reduce the attributable mortality and morbidity of sepsis. Developing novel therapeutic strategies to improve outcomes of sepsis remains an important focus of ongoing research in the field of critical care medicine. Apoptosis has recently been identified as an important mechanism of cell death and evidence suggests that prevention of cell apoptosis can improve survival in animal models of sepsis and endotoxaemia. In this review article, we summarise the critical role of apoptosis of the immune cells in the pathophysiology of sepsis and propose that blocking cell-signaling pathways leading to apoptosis may present a promising specific therapy for sepsis. Various methods to inhibit apoptosis including the cell surface Fas receptor pathway inhibitors, caspase inhibitors, over-expression of anti-apoptotic genes and small interfering ribonucleic acid therapy are discussed.

Variation in UDP glucouronyltransferase (UGT) genes associated with prostate cancer mortality

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Background: We investigated the association of germline genetic variation in hormone biosynthesis and metabolism genes with prostate cancer specific mortality in a cohort of advanced prostate cancer patients.

Methods: We successfully genotyped 852 single nucleotide polymorphisms (SNPs) from 97 genes in a cohort of 267 advanced prostate cancer patients at the time of progression to castration recurrence (CRPC) during on-going androgen ablation. Tagging SNPs with minor allele frequency (MAF) of >5% and r2 ≥0.8 were selected from HapMap, NIEHS and Seattle SNP databases. Medical records were queried for cause of death. The primary endpoint of time to prostate cancer specific mortality (PCSM), was pre-defined as time from development of CRPC to death from prostate cancer progression. Principle components analysis was used for gene-levels tests, and to account for multiple testing, we calculated the false discovery rate (FDR). For SNP level results, hazard ratios (HR) and 95% confidence intervals (CI) were estimated using cox regression.

Results: The median age of the cohort was 72 years at CRPC. 43% had a Gleason score (GS)=8-10, 33% a GS=7, and 24% a GS<7. After a median follow-up of 1.8 years (IQ range: 0.8–3.3 years), 139 patients died, of which 107 were due to prostate cancer progression. In unadjusted gene level analyses, UGT1A7 (p=0.0059; FDR=0.19), UGT1A10 (p=0.0017; FDR=0.17) and UGT1A3 (p=0.0037; FDR=0.18) were associated with PCSM. After adjusting for age and GS, SNPs strongly associated with PCSM are listed in the Table .

Conclusions: Variation in UGT genes involved in hormone metabolism yield prognostic information in CRPC. Further validation is needed to develop these as prognostic biomarkers.

[Table: see text]

No significant financial relationships to disclose.

Use of variation in sex steroid methyl transferases to predict efficacy of androgen-deprivation therapy (ADT) in advanced prostate cancer

14

Background: We evaluated the association of germline variation in genes regulating hormonal pathways with duration of treatment response in prostate cancer patients receiving ADT, focusing on genes in the androgen biosynthesis (the C4 Δ; C5 Δ; C21 CYP pathways and the alternate “backdoor pathway”) and metabolism pathways.

Methods: We successfully genotyped 747 single nucleotide polymorphisms (SNPs) from 84 genes in a cohort of 304 patients with advanced prostate cancer who progressed on ADT. Tagging SNPs with a minor allele frequency (MAF) of >5% and r2 ≥0.8 were selected from HapMap, NIEHS and Seattle SNP databases. The primary endpoint was time to ADT failure, and we conducted a gene-level test (principal components), along with individual SNP level tests adjusted for patient age and Gleason score. To account for multiple testing, we calculated the false discovery rate (FDR), and FDRs of 0.10 were considered noteworthy.

Results: The median age of the cohort at ADT failure was 72 years (range 65-78 years), and the overall median time to ADT failure was 3.21 years (IQ [25-75]: 1.54-6.20 years). At the gene level, TRMT11 (tRNA methyltransferase 11 homologue) showed the strongest association with time to ADT failure (p<0.0008; adjusted p-value for FDR-0.068). Two of four TRMT11 tag SNPs were associated with time to ADT failure. The first was the intronic SNP rs1268121 (A>G) with a MAF of 15%, for which there was a positive association of median time to ADT failure with the number of variant alleles (p=0.023): 3.1 years for 0, 4.1 years for 1, and 5.9 years for 2 variant alleles. The second was the SNP rs6900796 (A>G) in the 3' untranscribed region with a MAF of 49%, for which the median time to ADT failure was 2.6 years for 0, 2.5 years for 1, and 3.8 years for 2 variant alleles (p=0.023). Four additional genes showed an association with ADT response at the p<0.10 level, including LOC390956, PRMT3, SLC7A6OS, and WBSCR22, although all FDRs were >0.95.

Conclusions: Variation in TRMT11 was associated with time to ADT failure. Confirmation of these findings in an independent cohort is needed.

No significant financial relationships to disclose.

Properties of Piezoelectric Pzt Thin Films for Microactuator Applications

The piezoelectric properties of lead zirconate titanate (PZT) thin films deposited on thick silicon substrates and thin silicon membranes were investigated using optical interferometry. The effect of the geometrical constraints and clamping effects on the piezoelectric response is discussed. The study of the dielectric permittivity and the loss as a function of the amplitude of the alternating electric field reveals that extrinsic contributions to the dielectric permittivity become active at large fields. The DC electric field has the effect of freezing out the extrinsic contributions. The influence of the dielectric loss on the piezoelectric properties is discussed.

Ecotoxicity of a brominated flame retardant (tetrabromobisphenol A) and its derivatives to aquatic organisms

The large use of tetrabromobisphenol A (B(4)BPA) in common products (plastics, electric and electronic equipments) has raised concern about its ecotoxicity. Physical and bio-degradations may lead to the formation of tetrabromobisphenol A derivatives like tri- (B(3)BPA), di- (B(2)BPA), monobromobisphenol A (B(1)BPA) and bisphenol A (BPA). However, little is known about the toxicity of these brominated derivatives. An appraisal on the ecotoxicity of B(4)BPA and its derivatives was carried out with several bioassays representing organisms (bacteria, algae, micro-invertebrates and fish) of different taxonomic groups present in aquatic ecosystems. Endpoint values showed that B(4)BPA was significantly less toxic than the other chemicals when tested with the Microtox and algal asssays. A similar trend was observed with other bioassays for BPA. One of the brominated derivatives was particularly toxic: B(2)BPA. The LuminoTox assay and the rainbow trout hepatocytes assay reported the most significant toxicity for this derivative. Its toxicity was also significantly higher than the other compounds barring B(3)BPA when tested with the micro-crustacean test.

TSG101 exposure on the surface of HIV-1 infected cells: implications for monoclonal antibody therapy for HIV/AIDS

HIV infection remains a major global public health problem, in part because of the ability of the virus to elude antiretroviral therapies. Most conventional drugs were designed to directly target virus-encoded mechanisms. However, there is increasing appreciation that certain host-encoded molecules are comparably important for the viral life cycle and could therefore represent potential antiviral targets. Prominent among these is TSG101, a cytoplasmic molecule that is "hijacked" by HIV and used to facilitate viral budding and release. In our present report, we demonstrate thatTSG101 is uniquely exposed on the surface of HIV-infected cells and is available to antibody-based therapies. We also characterize the development of a monoclonal antibody, CB8-2, which reduces virus production from infected cells. These studies demonstrate the potential of TSG101-directed antibodies to combat HIV/AIDS.

Identification of novel host-oriented targets for Human Immunodeficiency Virus type 1 using Random Homozygous Gene Perturbation

Background

Human Immunodeficiency Virus (HIV) is a global threat to public health. Current therapies that directly target the virus often are rendered ineffective due to the emergence of drug-resistant viral variants. An emerging concept to combat drug resistance is the idea of targeting host mechanisms that are essential for the propagation of the virus, but have a minimal cellular effect.

Results

Herein, using Random Homozygous Gene Perturbation (RHGP), we have identified cellular targets that allow human MT4 cells to survive otherwise lethal infection by a wild type HIV-1_NL4-3. These gene targets were validated by the reversibility of the RHGP technology, which confirmed that the RHGP itself was responsible for the resistance to HIV-1 infection. We further confirmed by siRNA knockdowns that the RHGP-identified cellular pathways are responsible for resistance to infection by either CXCR4 or CCR5 tropic HIV-1 variants. We also demonstrated that cell clones with these gene targets disrupted by RHGP were not permissible to the replication of a drug resistant HIV-1 mutant.

Conclusion

These studies demonstrate the power of RHGP to identify novel host targets that are essential for the viral life cycle but which can be safely perturbed without overt cytotoxicity. These findings suggest opportunities for the future development of host-oriented therapeutics with the broad spectrum potential for safe and effective inhibition of HIV infection.

Function-first approaches to improve target identification in cancer

Target discovery for cancer is undergoing a sort of revival with an increasing need for improved therapeutics. Likewise, the strategies to discover new and better therapeutic targets have come full circle, with greater emphasis placed upon targets that are functionally relevant to the disease process. In this article, we review the evolution of cancer target discovery and discuss random homozygous gene perturbation, an emerging technology that combines the practicality of screening for new targets by emphasizing function as the primary criterion, with cutting-edge advances in gene-based screening of all potential targets in a cell.

Incidence and factors related to flare-ups in a graduate endodontic programme

AIM

To investigate the incidence and factors related to endodontic flare-ups in nonsurgical root canal treatment (NSRCT) cases completed by graduate endodontic residents at University of Pennsylvania, USA.

METHODOLOGY

Residents at University of Pennsylvania enter all clinical patient records into an electronic database called PennEndo database. Analysis of records of 6580 patients treated from September 2000 to July 2005 revealed a total of 26 patients with flare-ups (0.39%). Patients were categorized to have undergone flare-up when they attended for an unscheduled visit and active treatment, and when they suffered from severe pain and or swelling after initiation or continuation of NSRCT. SAS software was used to develop a logistic regression model with flare-up as a dependent variable. Independent variables included in the model were: history of previous pain, one vs. two visit NSRCT, periapical diagnosis, tooth type, rotary versus hand instrumentation, and lateral versus vertical compaction of gutta-percha.

RESULTS

The odds for developing a flare-up in teeth with a periapical radiolucency were 9.64 times greater than teeth without a periapical radiolucency (P = 0.0090). There was no statistically significant difference in flare-ups between one and two visits NSRCT. The odds of developing a flare-up increased 40 fold when NSRCT was completed in three or more visits. However, this result may have been confounded by addition of an unscheduled visit in patients suffering from flare-ups. Other independent variables did not have any statistically significant correlations.

CONCLUSIONS

A low percentage of patients experienced flare-ups during NSRCT procedures. The presence of a periapical lesion was the single most important predictor of flare-ups during NSRCT.

Mandibular canal variant: a case report

The mandibular canal transmits the inferior alveolar artery, vein and the inferior alveolar nerve. From an embryological perspective, there might be three inferior dental nerves innervating three groups of mandibular teeth. During rapid prenatal growth and remodeling in the ramus region there is spread of intramembranous ossification that eventually forms the mandibular canal. Occurrence of bifid/trifid mandibular canals in some patients is secondary to incomplete fusion of these three nerves. Various types of bifid mandibular canals have been classified according to anatomical location and configuration. This case report highlights an unusual variant of the mandibular canal.