Stimulator of interferon genes is required for Toll-Like Receptor-8 induced interferon response

The innate immune system is equipped with multiple receptors to detect microbial nucleic acids and induce type I interferon (IFN) to restrict viral replication. When dysregulated these receptor pathways induce inflammation in response to host nucleic acids and promote development and persistence of autoimmune diseases like Systemic Lupus Erythematosus (SLE). IFN production is regulated by the Interferon Regulatory Factor (IRF) transcription factor family of proteins that function downstream of several innate immune receptors such as Toll-like receptors (TLRs) and Stimulator of Interferon Genes (STING). Although both TLRs and STING activate the same downstream molecules, the pathway by which TLRs and STING activate IFN response are thought to be independent. Here we show that STING plays a previously undescribed role in human TLR8 signaling. Stimulation with the TLR8 ligands induced IFN secretion in primary human monocytes, and inhibition of STING reduced IFN secretion from primary monocytes from 8 healthy donors. We demonstrate that TLR8-induced IRF activity was reduced by STING inhibitors. Moreover, TLR8-induced IRF activity was blocked by inhibition or loss of IKKε, but not TBK1. Bulk RNA transcriptomic analysis supported a model where TLR8 induces transcriptional responses associated with SLE that can be downregulated by inhibition of STING. These data demonstrate that STING is required for full TLR8-to-IRF signaling and provide evidence for a new framework of crosstalk between cytosolic and endosomal innate immune receptors, which could be leveraged to treat IFN driven autoimmune diseases.

Background

High levels of type I interferon (IFN) is characteristic of multiple autoimmune diseases, and while TLR8 is associated with autoimmune disease and IFN production, the mechanisms of TLR8-induced IFN production are not fully understood.

Results

STING is phosphorylated following TLR8 signaling, which is selectively required for the IRF arm of TLR8 signaling and for TLR8-induced IFN production in primary human monocytes.

Conclusion

STING plays a previously unappreciated role in TLR8-induced IFN production.

Significance

Nucleic acid-sensing TLRs contribute to development and progression of autoimmune disease including interferonopathies, and we show a novel role for STING in TLR-induced IFN production that could be a therapeutic target.

Impact of an Ultrasound Demonstration on Vascular Surgery Interest in Pre-Clinical Medical Students

OBJECTIVES

One strategy to address the impending shortage of vascular surgeons is to augment interest in the trainee pipeline. Endovascular procedures are unique to vascular surgery (VS), and endovascular simulations have proven effective at generating VS interest in the past. Like endovascular techniques, the use of ultrasound (US) testing in VS is unique among medical specialties. We hypothesized that an interactive US demonstration would increase VS interest in pre-clinical medical students.

METHODS

We created a 5-point Likert scale survey assessing interest in VS, understanding of VS, likelihood to further investigate VS, choosing VS as a rotational elective, and pursuing VS shadowing and research opportunities. This survey was administered 1 day before and 1 day after the demonstration. Results were compared via paired T-test. A VS attending assisted by a senior registered vascular technologist (RVT) covered physics, B-mode, and continuous, pulsed wave, and color Doppler in an interactive, hands-on experience. Our dedicated ultrasound simulation lab enabled simultaneous interactive virtual broadcast and in-person learning. All first- and second-year students at our medical school were invited via email.

RESULTS

512 students were invited, 39 attended, and 19 students who completed surveys were included. 68% were female. Attendance at the ultrasound demonstration resulted in a significant increase in students' interest in vascular surgery (p=0.012), understanding of vascular surgery (p<0.001), likelihood to further investigate vascular surgery (p<0.001), likelihood to choose a vascular surgery rotation (p<0.001), and likelihood to pursue vascular surgery shadowing and research opportunities (p<0.001). Though only 2 of 6 in-person attendees returned surveys, their increase in average response to all questions was higher than virtual attendees (+1.80 vs +0.91, p=0.043).

CONCLUSIONS

Attending an interactive US demonstration significantly increased pre-clinical medical students' interest in and understanding of VS. In-person and virtual attendance both had positive impact. Such a demonstration may be an effective tool to recruit students. It is imperative that we continue innovating to address the future shortage of vascular surgeons.

Clinical Course and Cardiac Complications of Hospitalized COVID-19 Patients

Purpose

We describe the hospitalization course, cardiac complications and echocardiographic findings in a subset of acutely ill hospitalized patients with COVID-19.

Methods

Patients admitted to a large academic hospital in Ontario, Canada from March-June 2020 with COVID-19 and who had an echocardiogram within 4-weeks of their diagnosis were included in this study. Their demographics, hospitalization details and echocardiographic findings were analyzed.

Results

76 patients are included in our study, 83% of whom required ICU. Mean age was 58.9 years (+/-15.7 years). Cardiovascular comorbidities were common: diabetes (35.5%), hypertension (50%), CKD (11.8%), prior CAD (13.2%) or stroke (11.8%). Median length of admission was 25.5 days (IQR 22days). Overall, in-hospital mortality was high at 35.5%, with increased mortality in the ICU vs. non-ICU group (32.9% vs. 15.4%). A large number of patients required invasive support: intubation (77.6%), Extracorporeal life support (23.7%), or renal replacement therapy (19.7%). Cardiac complications included new AF (13.2%), hemodynamically significant VT (3.9%), moderate or more pericardial effusion (2.6%) and acute stroke (9.2%). Echocardiographic analysis demonstrated that 7.9% of patients developed moderate or more LV dysfunction on visual assessment. RV dysfunction was more common (27.6%) with 11.8% being visually classified as moderate or greater in severity. High sensitivity troponin was elevated in 59.2% of patients and was statistically higher in patients experiencing cardiac complications (Chi-Square 0.005). Although not achieving significance, there was a trend towards elevated troponin and development of moderate or greater LV/RV dysfunction (Chi-square 0.30).

Conclusion

In acute patients hospitalized with COVID-19, there was a high prevalence of cardiovascular co-morbidities. Troponin elevations was common and associated with a significantly increased risk of cardiovascular events and a trend towards moderate or greater ventricular dysfunction.

Prioritizing a Research Agenda of Transitional Care Interventions for Childhood-Onset Disabilities

Transitional care interventions have the potential to optimize continuity of care, improve health outcomes and enhance quality of life for adolescents and young adults living with chronic childhood-onset disabilities, including neurodevelopmental disorders, as they transition to adult health and social care services. The paucity of research in this area poses challenges in identifying and implementing interventions for research, evaluation and implementation. The purpose of this project was to advance this research agenda by identifying the transitional care interventions from the scientific literature and prioritize interventions for study. A modified-Delphi approach involving two rounds of online surveys followed by a face-to-face consensus meeting with knowledge users, researchers and clinician experts in transitional care (n = 19) was used. A subsequent virtual meeting concluded the formulation of next steps. Experts rated 16 categories of interventions, derived from a systematic review, on importance, impact, and feasibility. Seven of the 16 interventions categories received a mean score rating of ≥7 (out of 10) on all three rating categories. Participants then rank ordered the reduced list of seven interventions in order of priority and the top four ranked interventions advanced for further discussion at a consensus meeting. Using the Template for Intervention Description and Replication (TIDieR) checklist as a guide, the participants identified that a study of a peer system navigator was worthy of future evaluation. This study highlighted that transitional care interventions are complex and multifaceted. However, the presence of a peer to support system navigation, advocacy and individual and family education was considered the most ideal intervention addressing the current gap in care. Future research, which aims to engage patients and families in a co-design approach, is recommended to further develop this intervention.

Association Between Three-Dimensional Left Ventricular Outflow Tract Area and Gradients After Myectomy in Hypertrophic Obstructive Cardiomyopathy

OBJECTIVE

Determine whether the intraoperative three-dimensional left ventricular outflow tract cross-sectional area may be inversely correlated with pressure gradients as a determinant of surgical success after septal myectomy in hypertrophic cardiomyopathy patients.

DESIGN

Perioperative data were obtained by retrospective review.

SETTING

Toronto General Hospital, University of Toronto, Toronto, Canada, a tertiary hospital.

PARTICIPANTS

The study comprised 67 patients with hypertrophic obstructive cardiomyopathy.

INTERVENTIONS

Transthoracic and intraoperative transesophageal echocardiographic assessment of pressure gradients. Transesophageal measurement of the three-dimensional left ventricular outflow tract cross-sectional area.

MEASUREMENTS AND MAIN RESULTS

The smallest left ventricular outflow tract area increased on average 1.883 cm² (98.3%) after septal myectomy. There was a significant correlation between the increase in the area and the transesophageal pressure gradients (r = -0.32; p = 0.01) after myectomy, but none with postoperative transthoracic gradients at rest (r = -0.10; p = 0.42). Postoperative transesophageal and transthoracic gradients were significantly correlated (r = 0.26; p = 0.04). The best risk factors to predict high residual gradients were preoperative transesophageal gradient >97 mmHg, postoperative transesophageal area <3.16 cm², and moderate or more residual transesophageal mitral regurgitation (specificity 89%, 81%, and 78%, respectively).

CONCLUSIONS

Three-dimensional left ventricular outflow tract area measurements with transesophageal echocardiography after myectomy correlated fairly well with postoperative transesophageal pressure gradients. Patients with residual transthoracic elevated gradients after surgery at follow-up had a smaller transesophageal area and higher transesophageal pressure gradients immediately after the procedure. However, transesophageal pressure gradients after myectomy correlated poorly with follow-up transthoracic gradients at rest.

Transitional Care Interventions for Youth With Disabilities: A Systematic Review

CONTEXT

Transition from the pediatric to the adult health care system is a complex process that should include medical, psychosocial, educational, recreational, and vocational considerations.

OBJECTIVE

In this systematic review, we aim to synthesize the evidence on transitional care interventions (TCIs) to improve the quality of life (QoL) for adolescents and young adults with childhood-onset disabilities, including neurodevelopmental disorders.

DATA SOURCES

Four electronic databases (Medline, Embase, PsycINFO, and Cumulative Index to Nursing and Allied Health Literature) were searched.

STUDY SELECTION

In the included studies, researchers examined TCIs for adolescents and young adults (12-24 years of age) with childhood-onset disabilities. Studies were experimental, quasi-experimental, and observational studies published in the last 26 years.

DATA EXTRACTION

Two reviewers independently completed study screening, data extraction, and risk-of-bias assessment.

RESULTS

Fifty-two studies were included. Five studies reported on QoL, but statistically significant improvements were noted in only 1 of these studies. Significant improvements were also found in secondary outcomes including disability-related knowledge and transitional readiness. TCIs targeted patients, families and/or caregivers, and health care providers and exhibited great heterogeneity in their characteristics and components.

LIMITATIONS

Inconsistent reporting on interventions between studies hindered synthesis of the relationships between specific intervention characteristics and outcomes.

CONCLUSIONS

Although there is limited evidence on the impact of TCIs on the QoL for youth with childhood-onset disabilities, there is indication that they can be effective in improving patient and provider outcomes. The initiation of transition-focused care at an early age may contribute to improved long-term health outcomes in this population.

P2618Association of left ventricular ejection fraction with mortality and hospitalizations

Background

Although 2-dimensional echocardiography (2DE) is widely used to measure left ventricular ejection fraction (LVEF), the prognostic value of 2DE-derived LVEF has not been clearly demonstrated in a broad range of patients, including those acutely hospitalized as well as ambulatory patients. In particular, the prognostic value of echocardiographic LVEF has not been demonstrated for cardiovascular and heart failure hospitalizations.

Purpose

To determine if greater degrees of LV dysfunction are associated with progressively increasing risks of death or cardiovascular hospitalizations among patients undergoing echocardiography in hospital or outpatient settings.

Methods

We examined quantitative LVEFs from patient-level echocardiographic reports at 3 large hospital laboratories, which were linked to the Canadian Institute for Health Information hospitalization database and to death registries in Ontario, Canada. LVEF was categorized as <25%, 25–35%, 36–45%, or 46–55% (reference). Analyses were performed using cause-specific hazard competing risk models and stratified by: a) outpatient vs. inpatient echocardiogram, and b) if inpatient study, whether the reason for hospitalization was cardiac or noncardiac in nature.

Results

In the echocardiographic cohort of 27,323 patients (median age 68 [IQR: 58–77], 14,828 women [31.7%]), greater reductions in LVEF were associated with higher rates of all-cause mortality, with adjusted hazard ratios (95% CI) of 1.67 (1.57, 1.77) for LVEF <25%, 1.30 (1.24, 1.36) for LVEF 25–35%, and 1.17 (1.11, 1.23) for LVEF 36–45%, compared to LVEF 46–55% (all p<0.001). The cumulative incidence of cardiovascular death was higher as LVEF progressively worsened (Figure). The rate of heart failure hospitalizations was also increased with hazard ratios of 1.71 (1.59, 1.85) for LVEF <25%, 1.39 (1.31, 1.48) for LVEF 25–35%, and 1.21 (1.13, 1.29) for LVEF 36–45%, compared to LVEF 46–55% (all p<0.001). Cardiovascular hospitalizations were also increased with hazard ratios of 1.35 (1.27, 1.42), 1.21 (1.16, 1.27), and 1.13 (1.07, 1.18) for LVEFs <25%, 25–35%, and 36–45%, respectively (all p<0.001). The risk of mortality and hospitalizations increased comparably with greater reductions in LVEF during both inpatient cardiac or noncardiac admissions (p<0.001).

Cumulative incidence of CV death

Conclusions

Quantitative LVEF assessed by 2DE is potent prognostically and was able to stratify the risk of both death and hospitalization outcomes in a wide range of clinical settings. Patients with reduced LVEF measured on inpatient or outpatient echocardiograms, and even in the context of non-cardiac admission, should be considered an at-risk group in whom quality of care metrics could be evaluated in future studies.

Acknowledgement/Funding

Canadian Institutes of Health Research, Heart and Stroke Foundation, and the Ted Rogers Centre for Heart Research

Necrotising fasciitis in the North East of Scotland: a 10-year retrospective review

INTRODUCTION

Necrotising fasciitis is a life-threatening rapidly progressing bacterial infection of the skin requiring prompt diagnosis and treatment. Optimum care warrants a combination of surgical debridement, antibiotics and intensive care support. All cases of necrotising fasciitis in 10 years in the North East of Scotland were reviewed to investigate and improve patient care.

METHODS

Cases between August 2006 and February 2016 were reviewed using case notes and electronic hospital records. Data including mode of admission, clinical observations, investigations, operative interventions, microbiological and clinical outcomes was collected and reviewed. Analysis required multidisciplinary input including microbiology, infectious disease, trauma and orthopaedics, plastic surgery and intensive care teams.

RESULTS

A total of 36 cases were identified. The mean laboratory risk indicator for necrotising fasciitis (LRINEC) score was 7 and 86% of patients fulfilled the criteria for necrotising fasciitis. Patients were commonly haemodynamically stable upon admission but deteriorated rapidly; 36% of patients had a temperature of over 37.5 degrees C on initial observations; 29/36 patients were discharged, 6 patients died acutely (acute mortality rate of 17%); 18/31 of cases were polymicrobial with Streptococcus pyogenes, the common organism. Six amputations or disarticulations were performed from a total of 82 operations in this group, with radical debridement the usual primary operation. The mean time to theatre was 3.54 hours. Highly elevated admission respiratory rate (50 breaths/minute) was associated with increased mortality.

CONCLUSIONS

Necrotising fasciitis presents subtly and carries significant morbidity and mortality. A high index of suspicion allows early diagnosis and intervention. We believe that a pan-specialty approach is the cornerstone for good outcomes.

Abstract P2-06-01: Characterisation of C11orf67, an oncogenic driver in a new subtype of aggressive endocrine receptor positive breast cancer

The recent integration of both genomic and transcriptomic datasets have added a further dimension to the landscape of breast cancer (BrCa) subtyping, defining novel functional subgroups with distinctive oncogenic drivers that carry important implications for therapy. This integrative clustering has unveiled a novel subtype of hormone receptor positive (HR+) BrCa associated with high proliferation and very poor survival characterised by copy number amplification and overexpression of a cluster of candidate oncogenic drivers at the 11q13.5-14 locus (1). At the heart of this amplicon we have demonstrated the selective overexpression of C11orf67/AAMDC (Adipogenesis associated Mth938 domain containing) which encodes a hypothetical protein of 122 aa with unknown function. In a pilot tissue microarray of 75 BrCa cases C11orf67 amplification and expression were significantly correlated with hormone receptor positivity. These positive cases also demonstrated high risk features with 75% demonstrating lymph node involvement.

In functional elucidation studies knockdown of C11orf67 in the highly expressing T47D cell line lead to decreased cell proliferation, cell migration, anchorage independent cell growth and induction of senescence. T47D xenografts with stable shRNA-induced C11orf67 knockdowns introduced into BALB/c mice showed significantly lower tumour volumes relative to T47D with empty vector. A genome wide analysis of these T47D-C11orf67 shRNA cells compared to T47D-empty vector cells using the Illumina HumanHT-12 platform demonstrated 40 differentially expressed genes. Network analysis revealed a proliferation node, enriched in cell cycle proteins, and a metabolic node comprising several biosynthetic enzymes such as MTHFD1L involved in one-carbon folate metabolism. Supporting this link and pointing to potential utility in chemotherapy selection, induction of ectopic C11orf67 expression in MCF7 cells increased sensitivity to fluorouracil and methotrexate but not to paclitaxel.

Investigating potential novel binding partners and effectors, in yeast two hybrid screening C11orf67 was a found to associate strongly with RABGAP1L, a protein involved in controlling GTPase signalling, protein trafficking, and autophagy.

Exploring the molecular cues that control C11orf67 expression, our data suggest the locus is regulated by transcription factors associated with high proliferation and metabolic control, notably Myc and NFkB, as well as HRs. E2 lead to a significant down-regulation of C11orf67 in T47D cells, which was reversed by the antiestrogen drug tamoxifen, whereas PG significantly increased C11orf67 levels. In keeping with this MCF7 cells ectopically expressing C11orf67 were resistant to the anti-proliferative effects of tamoxifen compared to the parent cell line.

These observations endorse C11orf67 as a novel oncogenic driver with exciting therapeutic potential, which could serve to distinguish the HR+ tumours at high risk of relapse and guide both the selection of current chemotherapeutical and endocrine treatments as well as the design of future precision therapeutics, notably anti-folate/one carbon drugs and novel endocrine agents.

References

1. Curtis et al. Nature. 2012 Jun 21;486 (7403):346-52.

Citation Format: Redfern A, Rashwan R, Sorolla A, Ratajska M, Kardas I, Kuzniacka A, Parry J, Curtis C, Woo A, Sgro A, Biernat W. Characterisation of C11orf67, an oncogenic driver in a new subtype of aggressive endocrine receptor positive breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P2-06-01.

Hardware failure and spinal pseudoarthrosis causing autonomic dysreflexia: a report of two cases

STUDY DESIGN

Case report.

OBJECTIVES

To describe two cases of hardware failure with pseudoarthrosis causing autonomic dysreflexia. The first patient was a 24-year-old woman with T3 ASIA (American Spinal Injury Association)-A paraplegia who developed complete failure and breakage of the Luque rods at the T11-12 region. The second woman was a 36-year-old T5 ASIA-A complete paraplegic who fractured her Harrington rods at T12 and L1 bilaterally.

SETTING

Saskatoon City Hospital, Saskatchewan, Canada.

METHODS AND RESULTS

Both patients underwent operation for surgical fixation. In both cases, stabilization and fusion of the spinal deformity abolished the autonomic dysreflexia.

CONCLUSION

Owing to the failure of spine-stabilizing hardware, sitting upright may cause an afferent stimulus that triggers the onset and worsening of symptoms associated with autonomic dysreflexia. Therefore, in contrast to current acute treatment regimes, lying down may be preferred to sitting upright (to decrease blood pressure) as a means to relieve the afferent stimulus. Surgical correction and hardware replacement alleviated the symptoms in these two patients.

Mutations of the beta myosin heavy chain gene in hypertrophic cardiomyopathy: critical functional sites determine prognosis

OBJECTIVES

To assess patients with different types of mutations of the beta myosin heavy chain (beta MHC) gene causing hypertrophic cardiomyopathy (HCM) and to determine the prognosis of patients according to the affected functional domain of beta MHC.

DESIGN AND SETTING

Cohort study of subjects referred to an HCM clinic at an academic hospital.

PATIENTS

70 probands from the HCM clinic were screened for mutations of the beta MHC gene and 148 family members of the genotype positive probands were further assessed. The control group for the genetic studies consisted of 106 healthy subjects.

MAIN OUTCOME MEASURES

Direct DNA sequencing was used to screen 70 probands for mutations of the beta MHC gene. Family members underwent genotypic and detailed clinical, ECG, and echocardiographic assessments. The survival of genotype positive subjects was evaluated according to the type of functional domain affected by the missense mutation and according to phenotypic characteristics.

RESULTS

A mutation of the beta MHC gene was detected in 15 of 70 probands (21%). Of 148 family members studied in these 15 families, 74 were identified with a beta MHC defect. Eleven mutations were detected, including four novel mutations: Ala196Thr, Pro211Leu, Val404Leu, and Arg870Cys. Median survival was 66 years (95% confidence interval (CI) 64 to 77 years) in all affected subjects. There was a significant difference in survival between subjects according to the affected functional domain (p = 0.02). Significant independent predictors of decreased survival were the non-conservative (that is, associated with a change in the amino acid charge) missense mutations that affected the actin binding site (hazard ratio 4.4, 95% CI 1.6 to 11.8; p = 0.003) and those that affected the rod portion of beta MHC (hazard ratio 4.8, 95% CI 1.2 to 19.4; p = 0.03). No phenotypic characteristics were associated with decreased survival or cardiovascular morbidity.

CONCLUSIONS

The type of beta MHC functional domain affected by the missense mutation is predictive of overall prognosis in HCM.

Appendectomy in patients undergoing laparoscopic surgery for pelvic pain

STUDY OBJECTIVE

To evaluate pathologic findings in appendixes of women undergoing laparoscopic surgery for pelvic pain.

DESIGN

Retrospective study (Canadian Task Force classification II-2).

SETTING

Private practice specializing in gynecologic endoscopic surgery.

PATIENTS

One hundred ninety women.

INTERVENTION

Prophylactic appendectomy.

MEASUREMENTS AND MAIN RESULTS

On pathologic evaluation, 154 appendixes were diagnosed as having one or more abnormal findings, such as endometriosis, carcinoid, chronic appendicitis, periappendicitis, fibrous obliteration, and lymphoid hyperplasia.

CONCLUSION

Women undergoing laparoscopic surgery for pelvic pain should be counseled on the high frequency of abnormal findings in the appendix, including endometriosis. Prophylactic appendectomy appears to be a worthwhile consideration in these patients.

Risk factors for heterotopic ossification in total hip arthroplasty

This study prospectively evaluated 928 patients with 1318 primary total hip replacements for heterotopic ossification (HO). The mean clinical and radiological follow-up was 2.5 years (range 1.5-3.6 years). HO was noted in 44.6% of all total hips replaced. It was graded as mild (Brooker 1) in 29.2%, moderate (Brooker 2) in 10.5%, and severe (Brooker 3 and 4) in 4.2%. The following factors showed a significantly increased risk of HO: hypertrophic osteoarthritis, HO after contralateral total hip replacement, trochanteric osteotomy, lateral or anterolateral approach, previous hip surgery, subtrochanteric femoral osteotomy, and male gender (p < 0.05 in chi-square analysis of independence and multivariable analysis). Patients with rheumatoid arthritis showed less HO. A combination of any of these factors resulted in a significant increase in the risk of developing HO.

Maxillary sagittal and vertical displacement induced by surgically assisted rapid palatal expansion

The purpose of this study was to investigate the sagittal and vertical effects on the maxilla induced by surgically assisted rapid palatal expansion. Twenty patients (average age, 25.6 years) who required a surgically assisted rapid palatal expansion procedure were available for this study. Each patient was banded with a Haas-type palatal expander, maxillary surgery was performed, and the expander was activated. Presurgical and postexpansion lateral cephalograms were taken for each patient. The measurements of SNA, Frankfort horizontal-nasion-A point, sella-nasion-palatal plane, A-point-nasion-perpendicular (in millimeters), 1-nasion-A-point, 1-sella-nasion, 1-nasion-perpendicular (in millimeters) were made on each cephalogram, and the presurgical and postexpansion tracings were superimposed on the cranial base to determine the changes in the anterior nasal spine and posterior nasal spine positions. Results showed that from the presurgical cephalogram to the postexpansion cephalogram SNA, Frankfort horizontal-nasion-A point and A-point-nasion-perpendicular had a mean increase of 0.60 degrees (P <.05), 0.65 degrees (P <.05), and 0.55 mm (P <.05), respectively; 1-nasion-A-point decreased 2.18 degrees (P <.05) and 1-sella-nasion decreased 1.53 degrees (P <.05). No significant maxillary vertical displacement was noted from the first cephalogram to the second. In conclusion, surgically assisted RPE did not significantly affect the maxilla vertically; however, it did induce a slight forward movement of the maxilla and a slight retroclination of the maxillary incisors sagittally (P <.05).

Gluteus minimus-induced femoral head deformation in dysplasia of the hip

Lateral notching of the femoral head is considered pathognomonic for spastic subluxation of the hip. Less frequently, flattening is seen with extrusion of the femoral head in nonspastic hip dysplasia. The aim of this study was to throw light on its underlying pathomechanism. On the radiographs of 297 hips with developmental dysplasia, lateral flattening of the femoral head was seen in 18 hips (6%), but notching was present in only 1. Of 7 dysplasias due to cerebral palsy, 6 showed lateral notching. The gluteus minimus was felt to be responsible for the lateral femoral head changes as the muscle counteracts lateral migration of the femoral head. Intraoperative dissection of 3 hips supported this view. 1 hip with developmental dysplasia and lateral notching was subjected to a periacetabular osteotomy. At surgery, the tendon of the gluteus minimus was found to fit tightly into the notch. Of 2 hips with spastic dysplasia, 1 presented with and the other without lateral notching. In the hip with lateral notching, the gluteus minimus had a normal appearance and it lay in the defect of the femoral head. In the hip without notching, the gluteus minimus was atrophied with signs of fatty degeneration. We therefore believe that lateral notching is a sign of hypertonicity of the gluteus minimus muscle.

Modulation of glutathione S-transferase alpha by hepatitis B virus and the chemopreventive drug oltipraz

Persistent infection by hepatitis B virus (HBV) and exposure to chemical carcinogens correlates with the prevalence of hepatocellular carcinoma in endemic areas. The precise nature of the interaction between these factors is not known. Glutathione S-transferases (GST) are responsible for the cellular metabolism and detoxification of a variety of cytotoxic and carcinogenic compounds by catalysis of their conjugation with glutathione. Diminished GST activity could enhance cellular sensitivity to chemical carcinogens. We have investigated GST isozyme expression in hepatocellular HepG2 cells and in an HBV-transfected subline. Total GST activity and selenium-independent glutathione peroxidase activity are significantly decreased in HBV transfected cells. On immunoblotting, HBV transfected cells demonstrate a significant decrease in the level of GST Alpha class. Cytotoxicity assays reveal that the HBV transfected cells are more sensitive to a wide range of compounds known to be detoxified by GST Alpha conjugation. Although no significant difference in protein half-life between the two cell lines was found, semi-quantitative reverse transcription-polymerase chain reaction shows a reduced amount of GST Alpha mRNA in the transfected cells. Because the HBV x protein (HBx) seems to play a role in HBV transfection, we also demonstrated that expression of the HBx gene into HepG2 cells decreased the amount of GST Alpha protein. Transient transfection experiments using both rat and human GST Alpha (rGSTA5 and hGSTA1) promoters in HepG2 cells show a decreased CAT activity upon HBx expression, supporting a transcriptional regulation of both genes by HBx. This effect is independent of HBx interaction with Sp1. Treatment with oltipraz, an inducer of GST Alpha, partially overcomes the effect of HBx on both promoters. Promoter deletion studies indicate that oltipraz works through responsive elements distinct from AP1 or NF-kappaB transcription factors. Thus, HBV infection alters phase II metabolizing enzymes via different mechanisms than those modulated by treatment with oltipraz.

Effect of denture cleansers, surface finish, and temperature on Molloplast B resilient liner color, hardness, and texture

PURPOSE

The purpose of this study was to compare color, texture, and Shore A hardness of a resilient silicone denture liner with as-polymerized, roughened, or pumiced surfaces after treatment with perborate-, persulfate-, or hypochlorite-containing denture cleansers at 25 degrees or 55 degrees.

MATERIALS AND METHODS

Fifty-eight specimens that each exhibited an as-polymerized, a roughened, and a pumiced area were exposed to 5 different commercially available perborate-, persulfate-, or hypochlorite-containing denture cleansers at 25 degrees or 55 degrees continuously for 4 (1/2) months. The solutions were replaced twice a day. Control specimens were soaked in water with no cleanser. Before and after the 4 (1/2) -month cleaning regimen, the color, hardness, and texture of resilient liner surfaces were evaluated using a color densitometer, a Shore A durometer (Shore Instrument & Mfg Co, Freeport, NY), and a surface profilometer, respectively. Differences among groups after the cleanser treatment were determined using a repeated measures analysis of variance (alpha = 0.05) and a Tukey's Honestly Significant Difference post hoc test.

RESULTS

Roughened specimen surfaces after 25 degrees or 55 degrees cleanser treatment exhibited significant color loss with some perborate-containing cleansers compared with the control. Roughened specimens treated at 55 degrees with perborate-containing cleansers also exhibited significantly greater color loss than those treated with the persulfate-containing cleanser. With roughened surfaces, significantly greater hardness was found with some perborate-containing cleanser compared with a hypochlorite-containing cleanser after treatment at 25 degrees. No differences were observed in surface texture based upon cleanser treatment.

CONCLUSION

After silicone resilient denture liner treatment with certain perborate-containing denture cleansers, a greater amount of components could leach from the liner leading to a loss of color if the liner surface is rough.

Identification of the Yc1 glutathione S-transferase mRNA as the overexpressed species in a nitrogen mustard-resistant rat mammary carcinoma cell line

Glutathione transferase (GSTs) have been shown to be overexpressed in a number of tumor cell lines selected for resistance to chemotherapeutic drugs and have been implicated in some studies of clinical specimens. In tumor cell lines selected for resistance to chemicals that alkylate DNA, the isoform most frequently overexpressed is GST-Yc, a member of the alpha class GSTs. To date, two variations of the cDNA designated Yc1 with subtle differences have been described, and Yc2 is shown to be clearly distinct. Transfection of a Yc1 cDNA constitutively expressed in rat liver into rat mammary cancer cells confers resistance to alkylators, however, to a lesser extent than is observed in the cells selected for resistance. It has therefore been widely suggested that the GST that is overexpressed in selected resistant cells represents a distinct and novel isoform. We have previously described a rat mammary carcinoma cell line (MLNr) that is resistant to alkylating agents, and overexpresses a GST with characteristics similar to GST-Yc1 and not Yc2. It has many features common to the several other GST-Yc overexpressing alkylator resistant cell lines. We have cloned the specific Yc cDNA overexpressed in MLNr and analyzed it in detail and found that it is identical to one of the previously reported Yc1 cDNAs, suggesting that there is no additional Yc gene specifically induced by nitrogen mustards. Another hypothesis to explain the difference in the level of resistance in selected versus GST-Yc transfected cells is the lack of concurrent increased glutathione (GSH) in the transfectants, which is a common feature in the selected resistant cells. Experiments in which we modulated GSH levels suggest that this is not likely. These studies add to our speculation that other mechanisms may be involved in alkylator resistance.

Enhanced host cell reactivation capacity and expression of DNA repair genes in human breast cancer cells resistant to bi-functional alkylating agents

Human breast carcinoma (MCF7-MLNr) cells resistant to the bifunctional drugs L-phenylalanine mustard (L-PAM, 5-fold resistance), mechlorethamine (9-fold), cisplatin (3-fold), and BCNU (3-fold) were used to investigate the role of DNA repair in the development of resistance to alkylating agents. We have previously shown that neither L-PAM transport and metabolism nor glutathione-associated enzymes were altered in MCF7-MLNr cells, compared to the sensitive cells MCF7-WT. This study shows that treatment of pRSV-CAT plasmid with L-PAM at concentrations up to 1 microM proportionally inhibit the expression of chloramphenicol acetyl transferase (CAT) activity, while higher concentrations abolished CAT activity. pRSV-CAT reactivation was significantly increased when plasmid was transfected into MCF7-MLNr cells, compared to MCF7-WT cells. This indicates that resistant cells have more efficient capacity to recognize and repair L-PAM induced DNA damage. The mRNA expression of DNA nucleotide excision repair genes ERCC1, XPD (ERCC2), XPB (ERCC3), and polymerase beta was found to be similar in both the MCF7-WT and MCF7-MLNr cells. Western blot analysis also reveals no difference in the expression of ERCC1, AP endonuclease, poly (ADP-ribose) polymerase, and alkyl-N-purine-DNA glycosylase proteins. The lack of correlation between enhanced host cell reactivation capacity in resistant cells, and the expression of these specific DNA repair genes suggests that proteins encoded by these genes are not rate limiting steps for resistance to bi-functional alkylating drugs in human breast cancer cells.

Expression of a rat glutathione-S-transferase complementary DNA in rat mammary carcinoma cells: impact upon alkylator-induced toxicity

The role of glutathione-S-transferase (GST) in alkylator drug resistance has been studied in MatB rat mammary carcinoma cells. A series of GST transfectant cell lines was established by using an expression vector containing the complementary DNA for the rat GST Yc gene under regulation of the SV40 early region promoter and the antibiotic resistance plasmid pSV2neo. Transfectant cell lines expressing up to 4-fold higher total GST activity than in the parental wild type cell line were identified. Southern blot analysis confirmed a DNA fragment corresponding in size to the transfected GST Yc complementary DNA. Wild type MatB cells contain very low levels of Yc protein, whereas the Yc+ clones showed greatly increased amounts of the Yc subunit. The effect of increased GST Yc activity on the sensitivity of the transfected clones to various cytotoxic agents was assessed by using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide cell survival assay. The clones expressing recombinant GST Yc were more resistant to melphalan (6- to 12-fold), mechlorethamine (10- to 16-fold), and chlorambucil (7- to 30-fold). In late passage populations of the GST Yc+ clones that had been grown over a period of 14 months under continuous selection in G418, GST activity was decreased and it was paralleled by a decrease in Yc protein. These late passage clones with diminished GST Yc content also demonstrate a partial reversion toward the wild type phenotype as determined by cytotoxicity assays using melphalan, mustargen, and chlorambucil. Interstrand DNA cross-links induced by mechlorethamine were significantly lower at 0, 2, and 20 h posttreatment in one of the GST Yc+ clones when compared to wild type MatB cells. These studies indicate that GST Yc overexpression can confer resistance to alkylating agents and that this correlates with inhibition of DNA cross-link formation.

Drug resistance in cultured rat liver epithelial cells spontaneously and chemically transformed

Cultured rat liver epithelial cells (RLE) transformed with repeated treatments of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) demonstrate many features of the common biochemical phenotype of multidrug resistance (MDR) seen in vivo in 'resistant hepatocytes'. The cells have increased glutathione-S-transferase placental subunit (GST-Yp), gamma-glutamyltranspeptidase (GGT), glutathione (GSH) and glutathione peroxidase and are resistant to MNNG. Phenotypically identical RLE cells spontaneously transformed by selective culture conditions showed low levels of GGT and GST and were not resistant to MNNG. Both chemical and spontaneous transformants are cross resistant to doxorubicin although resistance is consistently greater in chemical transformants. No direct correlation was found between the degree of resistance to doxorubicin and MDR gene expression in either of the chemically or spontaneously transformed RLE cells. These observations suggest that in chemical carcinogenesis, other mechanisms of drug detoxification are involved and that MDR expression is not a consistent feature.

Effect of proliferative state on glutathione S-transferase isoenzyme expression in cultured rat liver epithelial cells

A specific biochemical phenotype is expressed during chemical hepatocarcinogenesis, which includes increased activity of the various isoenzyme forms of glutathione S-transferase (GST) composed of class alpha (Ya/Yc), class mu (Yb) and class pi (Yp) gene products. In vitro cell lines of normal and chemically transformed rat liver epithelial cells provide an opportunity to examine the regulation of expression of GST isoenzymes. We have studied the effect of the state of proliferation in culture on both the enzymic activity and the isoenzyme-specific mRNA expression. In normal rat liver epithelial cells (WB-F344), basal expression of the Yp subunit decreases, and of the Yb subunit increases, in cells at confluence compared with those in logarithmic-phase growth. In a subline of WB-F344 cells that has been chemically treated in vitro (GN6), there was greater Yp expression; however, the effect of growth status on both subunits was the same as in the nontransformed WB-344 cells, and the Ya subunit was not expressed. Inhibition of RNA synthesis with actinomycin D was limited, demonstrating pronged half-lives of the GST mRNAs, and shows a slightly greater decrease in GST-Yp specific mRNA levels in the confluent cells. Also nuclear run-off experiments demonstrate identical transcription rate in confluent and pre-confluent cells. These data suggest that the increase in Yp steady-state RNA in preconfluent cells is due to increased stability of the GST-Yp mRNA. In tumor cells derived from GN6 cells, the regulatory effects of growth status on the Yb and Yp expressions were absent. However, in these cells Ya subunit was expressed and this was subject to the effects of cell proliferation. We conclude that the growth status of cells in culture exerts a significant regulatory control on the GST isoenzyme gene expression. The effects are probably mediated at independent regulatory sites in each gene. The state of transformation of rat liver epithelial cells may determine responsiveness to this effect.

Glutathione depletion in human and in rat multi-drug resistant breast cancer cell lines

The effects of GSH depletion in a human breast cancer cell line and a multi-drug resistant subline (ADRr) were determined in a number of experimental conditions. The ADRr cells contained lower GSH concentration which cannot be explained solely on the basis of differences in cell kinetics, and yet the rate-limiting synthetic enzyme gamma-glutamylcysteine synthetase was increased 2-fold. Inhibition of GSH synthesis by BSO resulted in more rapid and more pronounced GSH depletion in ADRr compared to the wild-type cells, suggesting that enhanced GSH utilization and efflux in the resistant cells account for the lowered basal concentration. In addition, the gamma-glutamyl moiety salvage enzyme gamma-glutamyltranspeptidase was reduced markedly in the ADRr cell line. Since these cells have overexpression of the efflux pump protein P-glycoprotein, we examined the effects on cellular GSH of inhibition of the pump's function by verapamil. We found that verapamil significantly depleted cellular GSH. In a rat mammary carcinoma cell line selected in Adriamycin for multi-drug resistance, a similar molecular phenotype has been described including diminished cellular GSH concentration. Verapamil treatment of these cells also resulted in significant depletion of cellular GSH. These results are consistent with the recent report that combined treatment of BSO and verapamil has an additive effect on cytotoxicity. It is likely that decreased basal GSH concentration is due to oxidation and conjugation of it in reactions catalyzed by the enhanced peroxidase and GST found in these cells.

Expression of transforming growth factor-alpha in primary human colon and lung carcinomas

The expression of TGF-alpha in human colon and lung carcinoma cell lines has been reported previously, but its expression in primary tumours has not been described in detail. We have used the radio-immunoassay method to measure the specific content of immunoreactive TGF-alpha in the acid ethanol extracts of normal and cancerous tissues of human colon and lung. The average TGF-alpha content of colon carcinomas is 4 times that of the normal mucosa, and for non-small cell lung carcinomas it is twice that of the normal parenchyma. Because of variability in the TGF-alpha expression among individuals and in different segments of colon and lobes of lung, the ratio of TGF-alpha content of paired tumour and normal tissue was also calculated. On average, the tumour/normal ratio for colon carcinoma is higher than that for lung carcinoma. Although 55% of colon tumours show a ratio 4 times, or greater, only 33% of lung carcinomas demonstrate this ratio. The level of TGF-alpha in both colon and lung carcinomas does not correlate with histological type stage, grade nor degree of desmoplasia of these tumours. Northern blot analysis of total cellular RNA confirms the expression of an approximately 4.8 kb TGF-alpha mRNA in normal colonic mucosa and lung parenchyma. However, in contrast to the results of radio-immunoassay, significant over-expression of TGF-alpha mRNA is uncommon in primary human colon carcinomas.

Nosocomial legionellosis in surgical patients with head-and-neck cancer: implications for epidemiological reservoir and mode of transmission

A prospective pneumonia study was conducted simultaneously on head-and-neck surgery wards at two hospitals over 2 years; one hospital had a water supply contaminated with Legionella pneumophila but no record of having had a case of legionella pneumonia, and the other had just decontaminated its water supply because of known endemic nosocomial legionellosis. Special laboratory tests for legionella were done on all cases of nosocomial pneumonia irrespective of clinical impression. Over the first 18 months, the rate of nosocomial legionellosis was 30% at the first hospital and 0% at the second. Patients who underwent laryngectomy did not acquire the disease. Hyperchlorination at the first hospital was followed by a fall (p less than 0.01) in legionella pneumonias. Thus legionella pneumonias can be overlooked if special laboratory tests are not applied routinely, and surgical patients with head-and-neck cancer may be at high risk of nosocomial legionellosis because of the potential for pulmonary aspiration of contaminated water or orophyaryngeal microflora and/or frequent manipulation of the respiratory tract. This study demonstrates the benefits of examining the environment for legionella despite the absence of documented disease.

Discrimination between Rb+ and K+ by Escherichia coli

1. The K+ requirment of Escherichia coli is only partially fulfilled by Rb+. The molar growth yield on Rb+ was about 5% of that on K+ and the growth rate in Rb+-supplemented media is lower thatn in K+ influx by any of the four K+ transport systems of E. coli. The high-affinity Kdp system (Km = 2 micron) is poorly traced by 86Rb+. It discriminates against a 86Rb+ tracer at least 1000-fold. The two moderate affinity systems, the high-rate TrkA system (Km = 1.5 mM) and the moderate rate TrkD system (Km = 0.5 mM), discriminate against a 86Rb+ tracer by approximately 10-fold and 25-fold, respectively. 86Rb+ is preferred by the low-rate TrkF system and overestimates its K+ influx by 40%.

Tyrosine transaminase: development of daily rhythm in liver of neonatal rat

The development of the 24-hour rhythm in tyrosine transaminase activity was studied in the liver of the neonatal rat. A recognizable rhythm appears within 48 hours after birth, but it is opposite in phase to that observed in the adult rat. The reversal of the adult pattern occurs 21 to 23 days after birth and may represent a response to a change both in the eating pattern and in the amount of protein eaten.

Cytodifferentiation and membrane transport properties in LK sheep red cells

Young cells produced in LK sheep during rapid hematopoiesis after massive hemorrhage contain more K than the cells which are normally released into the circulation. The K content in these new cells falls to that characteristic of mature LK cells after a few days in the circulation. K transport properties in young and old cells before and after massive bleeding were studied. Young and old cells were separated by means of a density gradient centrifugation technique. Evidence showing that younger cells are found in the lower density fractions is presented. Active transport of K in the lightest fraction as measured by strophanthidin-sensitive influx was four to five times greater in red cells drawn 6 days after massive bleeding while the K leak as measured by strophanthidin-insensitive influx was only slightly larger. No change after bleeding was observed in older cells which had been present in the circulation prior to the hemorrhage. It is concluded that the high K content of young cells produced in LK sheep after bleeding is due to temporary retention of membrane K transport properties characteristic of HK cells. Thus, genetically determined modification of membrane transport properties has been shown to occur in nondividing circulating red cells.