The FDA Reclassification of Cervical Pedicle and Lateral Mass Screws: A Case Study in Regulatory History

The classification of medical devices by the Food and Drug Administration (FDA) involves rigorous scrutiny from specialized panels that designate devices as Class I, II, or III depending on their levels of relative risk to patient health. Posterior rigid pedicle screw systems were first classified by the FDA in 1984 and have since revolutionized the treatment of many spine pathologies. Despite this early classification by the FDA, posterior cervical pedicle and lateral mass screws were not reclassified from unclassified to Class III and then to Class II until 2019, nearly 35 years after their initial classification. This reclassification process involved a decades-long interplay between the FDA, formal panels, manufacturers, academic leaders, practicing physicians, and patients. It was delayed by lawsuits and a paucity of data demonstrating the ability to improve outcomes for cervical spinal pathologies. The off-label use of thoracolumbar pedicle screw rigid fixation systems by early adopters assisted manufacturers and professional organizations in providing the necessary data for the reclassification process. This case study highlights the collaboration between physicians and professional organizations in facilitating FDA reclassification and underscores changes to the current classification process that could avoid the prolonged dichotomy between common medical practice and FDA guidelines.

The efficacy of the National Surgical Quality Improvement Program surgical risk calculator in head and neck surgery: A meta-analysis

BACKGROUND

The National Surgical Quality Improvement Program surgical risk calculator (SRC) estimates the risk for postoperative complications. This meta-analysis assesses the efficacy of the SRC in the field of head and neck surgery.

METHODS

A systematic review identified studies comparing the SRC's predictions to observed outcomes following head and neck surgeries. Predictive accuracy was assessed using receiver operating characteristic curves (AUCs) and Brier scoring.

RESULTS

Nine studies totaling 1774 patients were included. The SRC underpredicted the risk of all outcomes (including any complication [observed (ob) = 35.9%, predicted (pr) = 21.8%] and serious complication [ob = 28.7%, pr = 17.0%]) except mortality (ob = 0.37%, pr = 1.55%). The observed length of stay was more than twice the predicted length (p < 0.02). Discrimination was acceptable for postoperative pneumonia (AUC = 0.778) and urinary tract infection (AUC = 0.782) only. Predictive accuracy was low for all outcomes (Brier scores ≥0.01) and comparable for patients with and without free-flap reconstructions.

CONCLUSION

The SRC is an ineffective instrument for predicting outcomes in head and neck surgery.

Sociodemographic Factors Predict Long-Term Attrition from Multidisciplinary Cleft Clinic

OBJECTIVE

Identify and describe factors associated with retention and attrition of patients during longitudinal follow-up at multidisciplinary cleft clinic.

DESIGN

Retrospective cohort study.

SETTING

Single, tertiary care center.

PATIENTS, PARTICIPANTS

Patients born between 1995 and 2007 with a diagnosis of cleft palate with or without cleft lip attending multidisciplinary cleft clinic.

INTERVENTIONS

None tested, observational study.

MAIN OUTCOME MEASURE(S)

Age at last clinical appointment with a multidisciplinary cleft team provider. Attrition was defined as absence of an outpatient appointment following 15 years of age.

RESULTS

Six hundred seventy-eight patients were included. The average age at last appointment across the entire cohort was 13.1 years (IQR 6.6-17.2). Patients who were Black (HR 1.60, 95% CI 1.10-2.32, p = 0.014) and other races (HR 1.90, 95% CI 1.22-2.98, p = 0.004) were more likely to be lost to follow-up compared to white patients. Publicly insured patients were more likely to experience attrition than those who were privately insured (HR 1.30, 95% CI 1.03-1.65, p = 0.030). Estimated income was not significantly associated with length of follow-up (p = 0.259). Those whose residence was in the fourth quartile of driving distance from our center experienced loss to follow-up significantly more than those who lived the closest (HR 2.04, 95% CI 1.50-2.78, p < 0.001).

CONCLUSIONS

There is a high degree of follow-up attrition among patients with cleft lip and palate. Race, insurance status, and driving distance to our center were associated with attrition in a large, retrospective cohort of patients who have reached the age of cleft clinic graduation.

Clinical practice guidelines in the management of pediatric foreign body aspiration and ingestion: a systematic evaluation using the AGREE II instrument

PURPOSE

Several clinical practice guidelines (CPGs) have been produced to optimize the diagnosis and management of pediatric foreign body aspiration and ingestion. However, to date there have been no critical evaluations of their methodological rigor or quality. Herein, we address this need via the Appraisal of Guidelines for Research and Evaluation (AGREE II) instrument.

METHODS

A literature search of Embase, MEDLINE via PubMed, and Scopus was performed up until February 25, 2021. Identified CPGs were then assessed by four independent reviewers trained in AGREE II. A scaled domain score of >60% was indicated as satisfactory quality. Intraclass correlation coefficients (ICC) were calculated to assess inter-reviewer agreement.

RESULTS

11 guidelines were assessed with only one being classified as high quality and others being either average (two) or low quality (eight). Domain 4 (clarity of presentation) achieved the highest mean score (66.41 ± 13.33%), while domain 5 (applicability) achieved the lowest score (10.80 ± 10.37%). ICC analysis revealed generally strong agreement between reviewers with a range of 0.60-0.98.

CONCLUSION

Quality appraisal using the AGREE II instrument suggests that the methodologic rigor and quality of current guidelines for the diagnosis and management of pediatric foreign body aspiration and ingestion need significant improvement.

Management of the Difficult Airway: An Appraisal of Clinical Practice Guidelines

OBJECTIVE

Management of the difficult airway can be a challenging process, which necessitates actionable recommendations from well-established guidelines. Herein, clinical practice guideline (CPG) quality is evaluated using the Appraisal of Guidelines for Research and Evaluation (AGREE II) instrument.

STUDY DESIGN

A systematic literature search was performed using Scopus, EMBASE, and MEDLINE via PubMed.

SETTING

Literature database.

METHODS

Data were abstracted from relevant guidelines and appraised by 4 expert reviewers in the 6 domains of quality defined by AGREE II. Intraclass correlation coefficients (ICC) were calculated across domains to quantify interrater reliability.

RESULTS

Twelve guidelines met the inclusion criteria. With a mean quality score of 83.1%, the highest quality guideline was authored by the American Society of Anesthesiologists (ASA). Low-quality content was observed in CPGs authored by the Japanese Society of Anesthesiologists (JSA) and the Chinese Collaboration Group for Emergency Airway Management (CCGEAM). Overall, deficits were most pronounced in domains describing the involvement of stakeholders, developmental rigor, and editorial independence. These findings were consistent among the panel of independent reviewers, with high ICC inter-rater reliability scores of 58.0% to 70.0% for the referenced domains.

CONCLUSION

By providing a comprehensive appraisal of guidelines, this report may serve as a reference for clinicians seeking to understand and improve upon the developmental quality of difficult airway management resources. According to AGREE II criteria for the quality of the guideline creation process, the 2022 ASA guideline outperforms its predecessors.

Radioactive Iodine in Differentiated Thyroid Carcinoma: A Systematic AGREE II Clinical Practice Guideline Appraisal

OBJECTIVE

Identify and appraise clinical practice guidelines (CPGs) for radioactive iodine (RAI) indications in differentiated thyroid carcinoma (DTC), and the treatment for radioactive iodine refractory (RAI-R) DTC using the Appraisal of Guidelines for Research and Evaluation II tool.

DATA SOURCES

MEDLINE (Pubmed), Ovid (EMBASE), and Scopus.

REVIEW METHODS

A systematic literature search was conducted to identify CPGs addressing RAI in DTC. CPGs were appraised by 4 independent reviewers in 6 distinct areas of quality. Scaled domain scores were subsequently calculated for each domain. Intraclass correlation coefficients were calculated for each domain to assess interrater reliability.

RESULTS

Sixteen guidelines were found addressing RAI indications for DTC. Of these 16, 9 also addressed the treatment of RAI-R DTC. A further 6 unique guidelines were identified that exclusively address RAI-R DTC, bringing the total number of guidelines to 22. The American Thyroid Association (ATA) guidelines for adult thyroid cancer were the highest scoring with a mean score of 83.5%. Two guidelines scored >60% in 5 or more domains, qualifying as "high" quality: ATA and British Thyroid Association. The highest scoring domain was domain 4: clarity of presentation (80.4%) while the lowest scoring domain was domain 5: applicability (38.6%).

CONCLUSION

Of the 22 guidelines identified, only two were "high quality." CPGs exclusively addressing the treatment of RAI-R DTC were weak with most guidelines scoring in the "low" quality range. This report reveals an unmet need for rigorously developed guidelines addressing indications for RAI in DTC, as well as the treatment for RAI-R DTC.

Medico-legal liability of injuries arising from laryngoscopy

OBJECTIVE

Dental and mucosal injuries from laryngoscopy in the peri-operative period are common medico-legal complaints. This study investigated lawsuits arising from laryngoscopy.

METHODS

Westlaw, a legal database containing trial records from across the USA, was retrospectively reviewed. Plaintiff and/or defendant characteristics, claimed injuries, legal outcomes and awards were extracted.

RESULTS

Of all laryngoscopy-related dental or mucosal injuries brought before a state or federal court, none (0 per cent) resulted in a defence verdict against the provider or monetary gain for the patient. Rulings in the patient's favour were observed only when laryngoscopy was found to be the proximate cause of multiple compounding complications that culminated in severe medical outcomes such as exsanguination, septic shock or cardiopulmonary arrest.

CONCLUSION

Proper laryngoscopy technique and a robust informed-consent process that accurately sets patients' expectations reduces litigation risk. Future litigation pursuits should consider the low likelihood of malpractice allegation success at trial.

Intraoperative angiography in neurosurgery: temporal trend, access site, and operative indication considerations from a 6-year institutional experience

BACKGROUND

Historically, the transfemoral approach (TFA) has been the most common access site for cerebral intraoperative angiography (IOA). However, in line with trends in cardiac interventional vascular access preferences, the transradial approach (TRA) and transulnar approach (TUA) have been gaining popularity owing to favorable safety and patient satisfaction outcomes.

OBJECTIVE

To compare the efficacy and safety of TRA/TUA and TFA for cerebral and spinal IOA at an institutional level over a 6-year period.

METHODS

Between July 2016 and December 2022, 317 angiograms were included in our analysis, comprising 60 TRA, 10 TUA, 243 TFA, and 4 transpopliteal approach cases. Fluoroscopy time, contrast dose, reference air kerma, and dose-area products per target vessel catheterized were primary endpoints. Multivariate regression analyses were conducted to evaluate predictors of elevated contrast dose and radiation exposure and to assess time trends in access site selection.

RESULTS

Contrast dose and radiation exposure metrics per vessel catheterized were not significantly different between access site groups when controlling for patient position, operative region, 3D rotational angiography use, and different operators. Access site was not a significant independent predictor of elevated radiation exposure or contrast dose. There was a significant relationship between case number and operative indication over the study period (P<0.001), with a decrease in the proportion of cases for aneurysm treatment offset by increases in total cases for the management of arteriovenous malformation, AVF, and moyamoya disease.

CONCLUSIONS

TRA and TUA are safe and effective access site options for neurointerventional procedures that are increasingly used for IOA.

Feasibility and safety of transradial intraoperative angiography for neurosurgery: An institutional experience

BACKGROUND

Transradial approach for neuroangiography is becoming increasingly popular because of the advantages demonstrated by interventional cardiology. Many advantages of radial access could be applied to intraoperative angiography.

OBJECTIVE

To report our institutional experience with transradial and transulnar intraoperative angiography, and evaluate its safety and feasibility.

METHODS

Intraoperative angiography through upper extremity vessels was attempted in 70 consecutive patients between April 2019 and December 2022. Data on patient characteristics and surgical indications, procedural variables, and complications were collected.

RESULTS

Of the 70 patients who underwent intraoperative angiography, 58.6% were female, and the mean age was 52.9 ± 14.0 years. The reason for surgery was aneurysm clipping in 42 (60.0%) cases. In total, 55 patients (78.6%) were positioned supine, 13 (18.6%) prone, and two (2.9%) were positioned three-quarters prone. Access was attempted via the radial artery in 60 (85.7%) patients and the ulnar artery in 10 (14.3%) patients. The procedure was successful in 69 of 70 cases (98.6%), as one required conversion to transfemoral approach due to significant spasm in the proximal right radial artery. The median fluoroscopy time was 8 min. No procedure was aborted, and no patient experienced access-site or angiography-related complications. Intraoperative angiography altered the surgical management in 3 (4.3%) cases. Re-access for follow-up angiography was unsuccessful in three (13.6%) of 22 due to radial artery occlusion.

CONCLUSIONS

Our institutional experience supports that transradial and transulnar intraoperative angiography is safe and feasible during neurovascular procedures for various indications and positions.

The impact of Verapamil for radial access in diagnostic cerebrovascular angiograms: A retrospective case-control study

INTRODUCTION

Different combinations of medications are utilized during wrist access for radial artery (RA) or ulnar artery (UA) catheterization in neuroendovascular procedures to preclude vasospasm. These "cocktails" commonly include the calcium channel blocker Verapamil, without established benefit. We analyze outcomes in patients with and without Verapamil in their "cocktail" by using a case-control cohort of our single-center experience.

METHODS

A prospective log of consecutive patients who underwent diagnostic cerebral angiograms using RA/UA access was retrospectively reviewed, and patients were grouped into Verapamil and non-Verapamil cohorts. The primary outcomes assessed were the presence of forearm skin rashes (hives) and RA/UA spasms. Our initial management included Verapamil (5 mg) in the cocktail, but Verapamil was removed after we noticed the development of hives in multiple patients immediately following its injection.

RESULTS

A total of 221 patients underwent 241 RA/UA diagnostic cerebral angiograms and were included in our analysis. One hundred and forty-nine patients (61.8%) underwent catheterization with Verapamil and 92 (38.2%) were catheterized without it. Four of the 149 patients in the Verapamil group (2.7%) developed hives during the procedure and were treated with Benadryl (25 mg). Of the 92 patients who did not receive Verapamil, there were zero (0%) cases of hives and one (1.1%) case of vasospasm.

CONCLUSION

Verapamil in the "cocktail" for wrist access diagnostic cerebral angiograms was associated with periprocedural hives, but not associated with a significant reduction in spasm compared to the non-Verapamil group. Our findings suggest that the administration of prophylactic Verapamil for these procedures may not be necessary.

A framework for advancing sustainable magnetic resonance imaging access in Africa

Magnetic resonance imaging (MRI) technology has profoundly transformed current healthcare systems globally, owing to advances in hardware and software research innovations. Despite these advances, MRI remains largely inaccessible to clinicians, patients, and researchers in low-resource areas, such as Africa. The rapidly growing burden of noncommunicable diseases in Africa underscores the importance of improving access to MRI equipment as well as training and research opportunities on the continent. The Consortium for Advancement of MRI Education and Research in Africa (CAMERA) is a network of African biomedical imaging experts and global partners, implementing novel strategies to advance MRI access and research in Africa. Upon its inception in 2019, CAMERA sets out to identify challenges to MRI usage and provide a framework for addressing MRI needs in the region. To this end, CAMERA conducted a needs assessment survey (NAS) and a series of symposia at international MRI society meetings over a 2-year period. The 68-question NAS was distributed to MRI users in Africa and was completed by 157 clinicians and scientists from across Sub-Saharan Africa (SSA). On average, the number of MRI scanners per million people remained at less than one, of which 39% were obsolete low-field systems but still in use to meet daily clinical needs. The feasibility of coupling stable energy supplies from various sources has contributed to the growing number of higher-field (1.5 T) MRI scanners in the region. However, these systems are underutilized, with only 8% of facilities reporting clinical scans of 15 or more patients per day, per scanner. The most frequently reported MRI scans were neurological and musculoskeletal. The CAMERA NAS combined with the World Health Organization and International Atomic Energy Agency data provides the most up-to-date data on MRI density in Africa and offers a unique insight into Africa's MRI needs. Reported gaps in training, maintenance, and research capacity indicate ongoing challenges in providing sustainable high-value MRI access in SSA. Findings from the NAS and focused discussions at international MRI society meetings provided the basis for the framework presented here for advancing MRI capacity in SSA. While these findings pertain to SSA, the framework provides a model for advancing imaging needs in other low-resource settings.

Clinical practice guidelines on management of infantile hemangioma: a systematic quality appraisal using the AGREE II instrument

Infantile hemangiomas (IH) are the most common benign tumors of childhood. Timely diagnosis and management of higher-risk IH is key in avoiding permanent disfigurement, visual impairment, and life-threatening airway compromise. Here, we identify and critically appraise existing clinical practice guidelines (CPGs) for IH diagnosis and management. A systematic search of MEDLINE, SCOPUS, and EMBASE was conducted until August 2021. Four independent reviewers assessed each CPG utilizing the Appraisal of Guidelines for Research and Evaluation, 2nd edition (AGREE II). An scaled domain score of ≥60% demonstrated adequacy in a given domain. Intraclass correlation coefficients (ICC) assessed agreement and scoring consistency between the reviewers. Eight CPGs were eligible and included for critical appraisal. Only one CPG was classified as 'high quality', with the remaining seven guidelines being 'average' (n = 3) or 'low' (n = 4) quality. Six guidelines (75.0%) were conducted via nonsystematic literature searches. The 'Applicability' (40.4%±14.0) and 'Rigor of development' (46.9%±17.3) domains achieved the lowest scores, while the highest average scores were in 'Scope and purpose' (76.7%±11.3) and 'Editorial independence' (90.8%±13.0). We found high consistency between the four independent reviewers, with 'very good' (n = 5) or 'good' (n = 1) interrater reliability in all six AGREE II domains. Based on the AGREE II instrument, there is only one available high-quality consensus statement on the diagnosis and management of IH. Low scores in 'Rigor of development' and 'Applicability' suggest notable weaknesses in the development process and reporting quality of existing IH CPGs. Future guidelines should be backed by systematic literature searches and focus on guideline clinical translation.

Clinical Practice Guidelines on Sentinel Lymph Node Biopsy for Melanoma: A Systematic Review and Quality Appraisal Using the AGREE II Instrument

Sentinel lymph node biopsy (SLNB) is a minimally invasive surgical procedure that is standard of care for the evaluation of clinically negative regional lymph nodes in patients with cutaneous melanoma. As the presence of metastases dictates patient prognosis and determines the need for further regional disease control or adjuvant therapy, SLNB is invaluable to clinical decision-making in patients presenting with melanoma. However, the indications for SLNB, specifically among patients with thin (<1 mm) or thick (>4 mm) melanomas, remain unclear. A number of clinical practice guidelines (CPGs) have been developed outlining recommendations for the role of lymph node biopsy in the management of melanoma. However, to date, their quality has not been critically appraised. Our objective was to systematically evaluate all available CPGs on this topic using the validated Appraisal of Guidelines for Research and Evaluation (AGREE II) instrument. Four total guidelines met the inclusion criteria and underwent appraisal. Only one CPG achieved a "high" quality rating, indicating scores of >60% in at least five of the six AGREE II domains. Across all CPGs, the lowest scoring domains were "Applicability" and "Stakeholder involvement," which had average scores of 41.2% and 48.3%, respectively. Based on the AGREE II instrument, the quality of existing CPGs for the indications of SLNB for melanoma is low. Future guidelines should be pilot tested to evaluate barriers to application and should utilize multidisciplinary guideline development teams that include patients and key stakeholders in addition to clinical experts from all relevant disciplines.

Clinical practice guidelines for management of medullary thyroid carcinoma: An AGREE II appraisal

PURPOSE

Medullary thyroid carcinoma (MTC) is a rare and aggressive form of thyroid neoplasia that requires multidisciplinary collaboration for effective management. We systematically appraise the quality of clinical practice guidelines (CPG) for the diagnosis and treatment of MTC using the Appraisal of Guidelines for Research and Evaluation (AGREE II) instrument.

MATERIALS AND METHODS

A systematic literature search was performed to identify CPGs pertaining to the diagnosis and treatment of MTC. Data were abstracted from guidelines meeting inclusion criteria and appraised by four independent reviewers in the six domains of quality defined by the AGREE II. Intraclass correlation coefficients (ICC) were calculated across domains to qualify interrater reliability.

RESULTS

Fourteen guidelines met inclusion criteria. No guideline achieved a score of >60 % in five or more AGREE II quality domains, which is required to gain designation as 'high' quality. One "average quality" guideline authored by the British Thyroid Association achieved a score of >60 % in three quality domains. The remaining thirteen (92.9 %) CPGs demonstrated low quality content, with deficits most pronounced in domains 3, 5, and 6, suggesting a lack of rigorously developed, clinically applicable, and transparent information.

CONCLUSIONS

As the diagnosis and treatment of MTC continues to evolve, the development of high-quality guidelines becomes increasingly important; few existing meet appropriate standards.

Quality appraisal of clinical practice guidelines for the use of radiofrequency ablation in the treatment of thyroid nodules and cancer

INTRODUCTION

Radiofrequency ablation (RFA) has gained significant recent global interest in the treatment of benign thyroid nodules and thyroid cancer. It is a relatively new, minimally invasive, thermal ablation technique that is an alternative to surgery. Several clinical practice guidelines (CPGs), consensus statements, and recommendations currently exist for the use of RFA in the treatment of benign thyroid nodules and thyroid cancers. These documents have considerable variability amongst them, and to date, their quality and methodologic rigor have not been appraised.

OBJECTIVE

To identify and perform a quality appraisal of clinical practice guidelines for RFA in the treatment of benign thyroid nodules and thyroid cancer using the Appraisal of Guidelines for Research and Evaluation (AGREE II) tool.

METHODS

A comprehensive literature search was performed in MEDLINE (via PubMed), EMBASE, and SCOPUS databases from inception to November 1, 2021. Four reviewers independently evaluated each guideline using the AGREE II instrument. Scaled domain scores were generated and the threshold used for satisfactory quality was >60%. Additionally, intraclass correlation coefficients (ICCs) were calculated to determine level of agreement between reviewers.

RESULTS

Seven guidelines were selected for final evaluation based on inclusion/exclusion criteria. Two guidelines were classified "high" quality, one "average" quality, and the rest "low" quality. The "Clarity and Presentation" (65.68 ± 26.1) and "Editorial Independence" (61.32 ± 25.8) domains received the highest mean scores, while the "Applicability" (32.14 ± 22.8) and "Rigor of Development" (45.02 ± 29.8) domains received the lowest mean scores. ICC statistical analysis showed high magnitude of agreement between reviewers with a range of (0.722-0.944).

CONCLUSION

Reflecting upon our quality appraisal, it is evident that the quality and methodologic rigor of RFA guidelines can be improved upon in the future. Our findings also elucidate the existing variability/discrepancies amongst guidelines in the indications and use of RFA.

Understanding the Pathogenesis of Lateral Supratentorial Neurenteric Cysts in Close Proximity to Other Vascular Pathologies: A Case Report and Review of Embryology

Several theories have been postulated to explain the embryogenesis of central nervous system (CNS) neurenteric cysts (NCs), but the exact mechanism remains poorly understood. Of those, the neurenteric canal migration hypothesis suggesting endodermal cell migration through the neurenteric canal and settling among ectodermal cells prior to neural tube closure might be the most robust as it explains, in contrast to other hypotheses, the existence of lateral supratentorial lesions, which are extremely rare, compared to their infratentorial counterparts. This mechanism might be supported by past medical history or the coexistence of CNS epidermoid cysts, which are thought to arise due to improper neural tube closure potentially increasing the probability of endodermal migration and subsequent NC development, yet there are no reported cases in the literature. We present a case of a patient with a history of a previously resected intracranial epidermoid cyst, representing three simultaneous pathologies including a laterally based right frontal NC along with a right corona radiata cavernous malformation lesion, and right middle cerebral artery bifurcation aneurysm. The three lesions were treated microsurgically in one operative session without complications. We discuss the case and review the relevant pathoembryology of laterally based supratentorial NC.

Quality appraisal of clinical practice guidelines for temporomandibular joint disorders using the AGREE II instrument

OBJECTIVE

We sought to systematically assess the quality of all clinical practice guidelines (CPGs) describing diagnosis and management of temporomandibular joint disorders (TMDs) using the Appraisal of Guidelines for Research and Evaluation instrument.

STUDY DESIGN

CPGs detailing all aspects of diagnosis and management (both conservative and nonconservative) for TMDs were reviewed.

RESULTS

Thirteen guidelines met inclusion criteria. The highest-scoring domain across guidelines was clarity of presentation (68.3%); the lowest-scoring domain was editorial independence (31.9%). The highest-scoring guideline described traditional Korean medicine approaches to the management of TMDs, earning a mean score of 79.2% across the six quality domains. Only three CPGs met a quality threshold of >60% in at least five domains, qualifying as 'high' per the Appraisal of Guidelines for Research and Evaluation criteria: these guidelines were the Korean medicine guidelines, Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) guidelines for diagnostic classification of TMDs, and the Japanese Society for the Temporomandibular Joint guidelines. An average intraclass correlation coefficient of 0.79 was calculated across all domains, denoting very strong agreement between independent reviewers.

CONCLUSION

We identified a significant lack of quality in multiple areas of CPG development for the diagnosis and therapeutic management of TMDs, suggesting a need for new comprehensive and rigorously developed guidelines addressing TMDs.

Safely performing percutaneous dilatational tracheostomies on COVID-19 patients in the intensive care unit: A standardized approach

BACKGROUND

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and the resulting coronavirus disease 2019 (COVID-19) have afflicted hundreds of millions of people in a worldwide pandemic. During this pandemic, otolaryngologists have sought to better understand risk factors associated with COVID-19 contamination during surgical procedures involving the airways such as tracheostomies.

OBJECTIVE

This study provides a standardized technique of performing an ultrasound (US)-guided percutaneous dilatational tracheostomy (PDT) on COVID-19 patients in the intensive care unit (ICU). It also outlines safety strategies for health care providers that includes proper use of personal protective equipment (PPE) and regular testing of otolaryngologists for COVID-19 contamination.

METHODS

This study analyzed data from 44 PDT procedures performed on COVID-19 patients in the ICU of hospitals in Sao Paulo and Santos, Brazil. The PDT procedures were conducted between April 2020 and August 2020, which coincided with a peak of the COVID-19 pandemic in São Paulo, Brazil. Surgeons were tested for COVID-19 using a two-stage serological enzyme-linked immunosorbent assay specific for SARS-CoV-2 antigens.

CONCLUSION

This study describes a safe standardized technique of US-guided PDT for COVID-19 patients in the ICU using a method that also decreases the risk of surgeon contamination.

Experimental analysis of the influence of cortical bone layers and bone quantity on implant primary stability

The systematic analysis of parameters impacting implant primary stability is difficult to achieve with human cadavers or animal models, particularly for complex trans-sinus procedures to determine the effects of cortical layers and bone engagement on implant stability before and after a simulated load in vitro. Solid rigid polyurethane blocks, partially intersected by an 8-mm-thick space, were created to imitate tri-cortical situations, the presence of the sinus cavity, and the posterior maxilla with different degrees of bone atrophy. Implants were inserted through the cavity at an angle of 30˚ (scenarios 1 and 2) to imitate the clinical protocol. Controls simulating uni-cortical anchorage and no sinus cavity were also included (controls 1 and 2). Four parameters were measured: peak insertion torque, insertion work, resistance to lateral bending loads and extraction torque. Scenarios 1 and 2 displayed similar peak insertion torque to control 2, where all three groups anchored equal amounts of bone surrogate. The distribution of surrogate bone in contact with trans-cavity implants influenced both extraction torque and the degree of lateral bending. Sufficient peak insertion torque can be attained with a trans-sinus tricortical implant anchorage providing sufficient apical and coronal bone is engaged.

Immediate full-arch rehabilitation of the severely atrophic maxilla supported by zygomatic implants: a prospective clinical study with minimum follow-up of 6 years

The aim of this study was to evaluate the outcomes of immediate full-arch prostheses supported by zygomatic implants alone or in combination with standard fixtures after a minimum of 6 years of loading. From October 2008 to April 2010, 15 patients with severely atrophic maxillae were treated using four zygomatic implants or two zygomatic implants in conjunction with two conventional fixtures. All subjects received a fixed screw-retained prosthesis within 3hours of surgery, while the final restoration was delivered after 6 months. Follow-up examinations were scheduled to evaluate zygomatic implant survival, conventional dental implant success, prosthetic success, plaque and bleeding scores, marginal bone loss for conventional dental implants, and patient satisfaction. Forty-two zygomatic fixtures and 18 standard implants were placed. Patients were followed up for a minimum of 79 months (range 79-97 months, average 90.61 months). No implant was lost, leading to implant and prosthetic survival rates of 100%. Bone loss for conventional implants averaged 1.39±0.10mm after 6 years of function, leading to a 100% implant success rate. High levels of patient satisfaction were recorded. These medium-term results indicate that immediate full-arch rehabilitation supported by zygomatic implants could be considered a viable treatment modality for the severely atrophic maxilla.

Immediate loading in the fully edentulous maxilla without bone grafting: the V-II-V technique

AIM

The aim of this prospective study was to evaluate a new surgical approach for the immediate rehabilitation of fully edentulous maxilla without any type of bone grafting.

METHODS

The technique named ''V-II-V'' consists of an immediately loaded full-arch bridge supported by six implants. Two distal implants engage the posterior wall of the maxillary sinus, being tilted 30-45 degrees relative to the occlusal plane. Two other tilted implants engage the anterior wall of the sinus, and finally two axial implants are inserted in the anterior maxilla. An acrylic provisional restoration is delivered within 4 hours of implant placement. At each follow-up, plaque and bleeding indexes were scored, marginal bone level change around tilted and axial implants were evaluated, and a questionnaire was compiled to assess patient's satisfaction for function and aesthetics.

RESULTS

Twenty-one patients were rehabilitated. A total of 126 implants were inserted. Nineteen prostheses were in function for more than 12 months. The average follow-up was 20 months (range 4-35 months). No implant failure occurred to date, leading to 100% survival rate and 100% prosthesis success. No complication was recorded. Peri-implant bone loss at axial and tilted fixtures was similar at one year, being 0.8 mm (SD 0.4, N.=28) and.0.9 mm (SD 0.5 mm, N.=56) respectively (P>0.05).

RESULTS

The ''V-II-V'' technique is a viable treatment modality for the immediate rehabilitation of the edentulous maxilla, avoiding bone grafting or sinus augmentation. Long-term evaluation is needed to confirm these encouraging preliminary

Sequential tamoxifen and aminoglutethimide versus tamoxifen alone in the adjuvant treatment of postmenopausal breast cancer patients: results of an Italian cooperative study

PURPOSE

To determine whether switching patients from tamoxifen to antiaromatase treatment would prevent some of the relapses or deaths that we assume would occur if tamoxifen were continued.

PATIENTS AND METHODS

Three hundred eighty postmenopausal breast cancer patients receiving adjuvant tamoxifen treatment for 3 years were randomized to either continue tamoxifen for 2 more years or to switch to low-dose aminoglutethimide (250 mg daily) for 2 years.

RESULTS

At a median follow-up of 61 months (range, 5 to 94 months), 59 events occurred in the tamoxifen group, and 55 occurred in the aminoglutethimide group. More treatment failures at distant sites, such as viscera (P =.02), were observed in the tamoxifen group. Although no differences in disease-free survival between the two groups have emerged so far, a significant trend favors aminoglutethimide in overall survival (P =.005) and breast cancer-specific survival (P =.06). Even if more patients in the antiaromatase group complained of drug-related side effects and more of them discontinued treatment (P =.0001), the number of cardiovascular events and, in general, of life-threatening adverse events was higher in the tamoxifen arm.

CONCLUSION

Switching patients from tamoxifen to aminoglutethimide treatment resulted in comparable event-free survival, but longer overall survival was achieved in patients who were switched to aminoglutethimide as compared with those who continued to receive tamoxifen. Should these preliminary results be confirmed by larger studies with a similar design, which are now testing the effectiveness of the new, more active, and tolerable aromatase inhibitors, sequencing tamoxifen with an aromatase inhibitor could become a preferable alternative to tamoxifen alone in early breast cancer patients.

Serial color-word test predicts outcome of pharmacological treatment for panic disorder

A group of 50 outpatients with Panic Disorder were given the Serial Color-Word Test at the beginning of a standard pharmacological treatment (selective serotonin reuptake inhibitors and benzodiazepines). A single treating psychiatrist, blind to test results, judged therapy outcome at a 5-mo. follow-up. Among the main types of adaptation to conflict assessed by the test (Stabilized, Cumulative, Dissociative, and Cumulative-Dissociative), the Stabilized pattern predicted a good therapy outcome. Response to therapy among the patients with a Stabilized pattern was judged as more often good and less often moderate or poor, compared with the members of the other three adaptation classes (p=.004), and specifically with the patients resorting to a Cumulative strategy (p=.005).

[The capacity of the rest-dobutamine gated SPECT protocol to predict contractile recovery after revascularization of myocardial dysinergic areas]

INTRODUCTION AND AIM

Gated-SPECT is a promising method to analyze myocardial viability. We have assessed the accuracy of a new protocol of rest/Dobutamine gated-SPECT, based on the evaluation of contractile reserve induced by 10 microg/kg/min of Dobutamine, to predict contractile recovery after revascularization of dysinergic myocardial territories.

PATIENTS AND METHODS

In a group of 36 patients submitted to percutaneous revascularization, we selected 40 vascular territories (21 left descending artery, 19 right coronary-circumflex) with severely depressed contractility (contrast ventriculography, center line method). Follow up evaluation at 6 months showed the absence of angiographic restenosis and control contrast ventriculography assessed the contractile changes of the selected territories, considering those with contractile restoration as viable. Before revascularization, rest/Dobutamine gated-SPECT study was applied and viability was defined as the presence of contractile reserve (positive or improvement [n = 21] and negative or impairment [n = 7]) with non viability being the absence of contractile reserve (n = 12). We analyzed the evolution of the ejection fraction in a group of 27 patients with impaired ventricular function and complete revascularization.

RESULTS

Gated-SPECT showed a sensitivity of 0.96 (95% CI 0.78-0.99) and a specificity of 0.78 (95% CI 0.48-0.94) in the diagnosis of viability. The ejection fraction (median [interquartile range]) increased after revascularization: 0.42 (0.15) vs 0.55 (0.22), Z = -3.9; p < 0. 001. The diagnosis of viability by gated-SPECT (p < 0.001) and the extent of severely depressed myocardium (p = 0.04) independently predicted the increase of the ejection fraction after revascularization.

CONCLUSIONS

The analysis of contractile reserve by rest/Dobutamine gated-SPECT is adequate to diagnose viability in territories with severely depressed contractility and independently predicts the increase of ejection fraction after revascularization.

Cyclophosphamide, methotrexate, and fluorouracil versus tamoxifen plus ovarian suppression as adjuvant treatment of estrogen receptor-positive pre-/perimenopausal breast cancer patients: results of the Italian Breast Cancer Adjuvant Study Group 02 randomized trial. boccardo@hp380.ist.unige.it

PURPOSE

To compare the efficacy of chemotherapy versus that of tamoxifen plus ovarian suppression in pre-/perimenopausal estrogen receptor-positive patients with early breast cancer.

PATIENTS AND METHODS

Patients were randomly assigned to receive either six cycles of a standard regimen of cyclophosphamide 100 mg/m(2) orally days 1 to 14, methotrexate 40 mg/m(2) intravenously (IV) days 1 and 8, and fluorouracil 600 mg/m(2) IV days 1 and 8 (CMF), with all drugs restarted on day 29, or 5 years of tamoxifen, 30 mg/d, plus ovarian suppression with surgical oophorectomy, ovarian irradiation, or monthly goserelin 3.6-mg injections. Disease-free survival was the main study end point. Overall survival and toxicity were additional end points.

RESULTS

Between 1989 and 1997, 120 patients were assigned to CMF and 124 to tamoxifen and ovarian suppression (oophorectomy, n = 6; ovarian irradiation, n = 31; and goserelin injections, n = 87). At the time of analysis (median follow-up time, 76 months; range, 9 to 121 months), 82 patients had relapsed and 39 had died. No difference between groups had emerged with respect to either disease-free or overall survival. Treatments were comparable even in respect to age, tumor size, and nodal status, although a nonsignificant trend favored patients with poorly differentiated tumors treated with CMF. Leukopenia, nausea, vomiting, stomatitis, and alopecia were significantly more common in patients treated with CMF. There were few patients who developed benign gynecologic changes in either group, and numbers were comparable.

CONCLUSION

The combination of tamoxifen with ovarian suppression seems to be safe and to yield comparable results relative to standard CMF.

Aspartic protease inhibitors. An integrated approach for the design andsynthesis of diaminodiol-based peptidomimetics

Aspartic proteases play key roles in a variety of pathologies, including acquired immunodeficiency syndrome. Peptidomimetic inhibitors can act as drugs to combat these pathologies. We have developed an integrated methodology for preparing human immunodeficiency virus (HIV)-1 aspartic protease diaminodiol inhibitors, based on a computational method that predicts the potential inhibitory activity of the designed structures in terms of calculated enzyme-inhibitor complexation energies. This is combined with a versatile synthetic strategy that couples a high degree of stereochemical control in the central diaminodiol module with complete flexibility in the choice of side chains in the core and in flanking residues. A series of 23 tetrameric, pentameric and hexameric inhibitors, with a wide range of calculated relative complexation energies (-47.2 to +117 kJ.mol-1) and predicted hydrophobicities (logPo/w = 1.8-8.4) was thus assembled from readily available amino acids and carboxylic acids. The IC50 values for these compounds ranged from 3.2 nM to 90 microM, allowing study of correlations between structure and activity, and individuation of factors other than calculated complexation energies that determine the inhibition potency. Multivariable regression analysis revealed the importance of side-chain bulkiness and rigidity at the P2, P2' positions, suggesting possible improvements for the prediction process used to select candidate structures.

[Lymphedema of the upper extremity in patients operated for carcinoma of the breast: clinical experience with coumarinic extract from Melilotus officinalis]

OBJECTIVES

The aim of this clinical study was to verify the therapeutic activity of cumarinic extract of Melilotus officinalis (CEMO) in patients with chronic lymphedema of the upper arm caused by lymphadenectomy for breast cancer. Cumarine, in fact, has antiedemic properties due to macrophagic action that stimulates proteolysis in the tissues affected by chronic lymphedema.

PATIENTS AND METHODS

In an open clinical study we enrolled 24 patients with chronic upper arm lymphedema due to post-lymphadenectomy of the axilla for breast cancer. 21 patients were eligible to receive 400 mg of CEMO containing 8 mg of cumarine in a sole daily administration for 6 months. We measure the circumference of the upper arm at 3 and 6 months from treatment. We evaluated the symptoms and tolerability through a questionnaire given to the patients at every clinical control.

RESULTS

Of the 21 (87.5%) patients eligible, only 14 (66.6%) were treated with CEMO according to protocol. Of these 11 patients (52.3%) had a reduction of the circumference of the affected arm of 5% with respect to base values. Three patients (14.2%) had no change. In 12 patients (57.1%) symptoms improved. As for tolerability: 3 patients (14.2%) had transitory gastrointestinal side-effects. There was worsening of lymphedema and symptoms in 4 patients (19%) that did not receive CEMO and were followed as controls. Three patients (14.2%) were not evaluable because they were lost to follow-up.

CONCLUSIONS

Cumarinic extract of Melilotus officinalis (CEMO) was effective in reducing lymphedema in 79% of the pts treated for a period of six months. The median reduction of the upper arm circumference was modest (5% with respect to initial values) but statistically significant (p = 0.048). Treatment with CEMO for lymphedema could be associated to the physiotherapy given to these patients such as manual lymph drainage (MLD).

[Validation of the three-dimensional method of sestamibi gated-SPECT in the calculation of the left ventricular ejection fraction in patients with ischemic heart disease. Comparison with contrast ventriculography]

INTRODUCTION AND OBJECTIVE

Tomography with acquisition synchronized with electrocardiography, gated-tomography, allows the assessment of left ventricular contractile function. The accuracy of a new method of gated-tomography, based on the three dimensional representation of the left ventricle to calculate the ejection fraction was validated by means of comparison with contrast ventriculography.

METHODS

We studied 85 patients with ischemic cardiopathy, and ejection fraction was calculated by contrast ventriculography and sestamibi-gated-tomography, at rest and throughout 10 micrograms/kg/min of dobutamine. Furthermore, we assessed the extent of perfusion defect, as well as the number of segments with activity below 50% of the total 13 segments in which the tomographic slices were divided.

RESULTS

Gated-tomography was significantly correlated to contrast ventriculography in the calculation of ejection fraction, both with acquisition at rest (r = 0.80) and throughout Dobutamine (r = 0.82). The average underestimation of gated-tomography calculation of ejection fraction was significantly greater for the rest study (-0.12 [IC 95% 0.04, -0.30]) than the dobutamine study (-0.07 [IC 95% 0.09, -0.24]). Patients with greater perfusion defects (4 o more segments) had no differences in underestimation of ejection fraction (-0.13 [IC 95% 0.03, -0.30] versus -0.11 [IC 95% 0.07, -0.29]).

CONCLUSIONS

The three-dimensional method of gated-tomography accurately assesses the ejection fraction. The underestimation determined by this method was lower in the study done with viable doses of dobutamine. The extent of perfusion defect had no deleterious effect on gated-tomography in the calculation of ejection fraction.

Rational design of inhibitors for drug-resistant HIV-1 aspartic protease mutants

This report describes a method for the assessment of inhibitor binding affinities to wild type HIV-1 aspartic protease and to its drug-resistant mutant forms. We have elaborated a refined method for molecular modeling of the 3D structures of mutant enzymes and enzyme-inhibitor complexes based on the crystal structure of the wild type form, which employs a full thermodynamic cycle. Model complexes of four HIV-1 aspartic protease mutants with ten analogs of the A77003 inhibitor were considered. Predictions of inhibition efficiency, resistance potential, and hydrophilicity of the redesigned A77003 analogs were obtained by employing molecular mechanics for the evaluation of enzyme-inhibitor complexation energy and the polarizable continuum model for the estimation of solvent effects. Simple qualitative indicators for structural modifications aimed at overcoming the emergence of HIV resistance to protease inhibitors and at increasing the bioavailability of pseudopeptide inhibitors are examined. A semi-quantitative method for the description of enzyme-ligand binding and its implications for the rational design of inhibitors with higher binding affinity towards emerging HIV PR mutants is presented.

Identification of the start sites for the 1.9- and 1.4-kb rat transforming growth factor-beta1 transcripts and their effect on translational efficiency

Three distinct transforming growth factor-beta1 (TGF-beta1) transcripts of 2.5, 1.9 and 1.4kb have been described, but the start sites and functional significance of the shorter transcripts are unknown. Here, we have cloned and sequenced a rat genomic fragment encoding approximately 1250 bases upstream of the start of the TGF-beta1 open reading frame. Using a combination of ribonuclease protection and 5' RACE-PCR analysis, we have mapped the start sites for the two shorter TGF-beta1 transcripts in NRP152 cells, a rat prostatic epithelial cell line that expresses all three transcripts at high levels. The 1.4-kb mRNA starts 25 bases upstream of the initiator AUG, whereas the 1.9-kb mRNA has two start sites 366 and 401 bases upstream of the AUG. Polysome analysis of the NRP152 cells indicates that the 1.9-kb transcript is very efficiently translated, whereas the 2.5- and 1.4-kb transcripts appear to be poorly translated. Differential regulation of TGF-beta1 transcript size may therefore represent an important mechanism for regulating TGF-beta1 protein levels.

Wide-spectrum antibiotic activity of synthetic, amphipathic peptides

PGYa and PGAa are synthetic, amphipathic, alpha-helical peptides that were designed using a novel "sequence template" approach. Their antimicrobial activity was tested against several pathogenic clinical isolates, most of which were multiply resistant to conventional antibiotics. PGYa appeared to be more active towards Gram-positive species (MIC = 0.5-4 microM), towards such Gram negative species as P. aeruginosa, X. maltophilia, E. coli, K. pneumoniae and S. enteritidis (MIC = 1.4 microM), and towards the filamentous fungus A. niger (MIC = 8 microM). Conversely, PGAa showed the greater activity towards three Candida species (MIC = 2.16 microM). The peptides were shown to have a bactericidal activity, resulting in a decrease of viability for both Gram-positive and -negative bacteria of 3-6 logs within 60 min. Scanning electron microscopy of S. aureus and E. coli treated with PGYa shows considerable roughening and blebbing of the bacterial surfaces providing conclusive evidence that the peptide is membrane active.

A computational study of the resistance of HIV-1 aspartic protease to the inhibitors ABT-538 and VX-478 and design of new analogues

Recent experimental findings with HIV-1 protease (HIV-1 PR) mutants containing variations at four residues, M46I, L63P, V82T and I84V, have shown that only mutants containing the latter two exhibit cross resistance to the inhibitors ABT-538 and VX-478. The V82T and I84V modifications in fact concern residues in the active site while the other two are in the flap (M46I) and hinge (L63P) domains of the enzyme. We have modelled the M46I/L63P, V82T/I84V and M46I/L63P/ V82T/I84V (4X) mutants of HIV-PR and computed their complexation energies with these two inhibitors. A good correlation was found between these complexation energies and the trend in published inhibition constants for these inhibitors. Reasons for the decrease in binding affinities with the two critical mutants (V82T/I84V and 4X) have also been elucidated in detail. Based on these findings, we have designed several analogues of ABT-538 and VX-478, some of which show a better calculated binding affinity towards both mutant and wild type PR.

Design of synthetic antimicrobial peptides based on sequence analogy and amphipathicity

Novel alpha-helical antimicrobial peptides have been devised by comparing the N-terminal sequences of many of these peptides from insect, frog and mammalian families, extracting common features, and creating sequence templates with which to design active peptides. Determination of the most frequent amino acids in the first 20 positions for over 80 different natural sequences allowed the design of one peptide, while a further three were based on the comparison of the sequences of alpha-helical antimicrobial peptides derived from the mammalian cathelicidin family of precursors. These peptides were predicted to assume a highly amphipathic alpha-helical conformation, as indicated by high mean hydrophobic moments. In fact, circular dichroism experiments showed clear transitions from random coil in aqueous solution to an alpha-helical conformation on addition of trifluoroethanol. All four peptides displayed a potent antibacterial activity against selected gram-positive and gram-negative bacteria (minimum inhibitory concentrations in the range 1-8 microM), including some antibiotic resistant strains. Permeabilization of both the outer and cytoplasmic membranes of the gram-negative bacterium, Escherichia coli, by selected peptides was quite rapid and a dramatic drop in colony forming units was observed within 5 min in time-killing experiments. Permeabilization of the cytoplasmic membrane of the gram-positive bacterium, Staphylococcus aureus, was instead initially quite slow, gathering speed after 45 min, which corresponds to the time required for significant inactivation in time-killing studies. The cytotoxic activity of the peptides, determined on several normal and transformed cell lines, was generally low at values within the minimum inhibitory concentration range.

Recharacterization of the start sites for the major human transforming growth factor-beta 1 mRNA

The start sites for the major human TGF-beta 1 transcripts have been reexamined. A comparison of ribonuclease and S1 nuclease protection analyses on native TGF-beta 1 mRNA and in vitro transcribed human TGF-beta 1 transcripts of defined sizes places the most 5' start site for the native TGF-beta 1 message approx. 50 nucleotides upstream from the previously published start site at base +1. Furthermore, the same techniques indicate that the apparent downstream start site at base +271 is an artefact due to the presence of an A + T-rich island in the middle of an otherwise highly G + C-rich sequence. This is not apparent if S1 nuclease protection is used alone, which emphasizes the importance of using the two techniques in combination for this type of analysis. Thus the major 2.5 kb TGF-beta 1 band seen on Northern blots comprises only mRNA transcribed from the more upstream of the two previously characterized promoters. This has important implications both for the transcriptional and translational regulation of this growth factor.

Healthcare decisions and product labeling: results of a consumer comprehension study of prototype labeling for proposed over-the-counter cholestyramine

This study was designed to determine whether randomly selected subjects could comprehend prototype consumer-oriented package labeling and inserts for over-the-counter cholestyramine, a nonsystemic lipid-lowering agent. The primary messages communicated in the label were that consumers should see their doctor before taking cholestyramine and should read the full package insert. In addition, the label communicated indication, dosage, and preparation, as well as key warnings about use with other medications. The insert reinforced the message about seeing the doctor before taking cholestyramine and before taking concurrent medications, further explained the purpose of the drug and its correct use, and provided information about the two types of cholesterol, risk factors for heart disease, and the importance of diet and exercise. A total of 1,806 randomly selected subjects were interviewed in their homes in 40 geographic regions. After examining the product container with one of the three labels being tested, they were given a questionnaire to test their understanding of the label communication points. They were then asked to read the package insert and tested on their understanding of the messages it communicated. Responses were analyzed by gender, age, and education level, as well as by label format. For the education-level subgroup analysis, the high-school-nongraduate group was supplemented by 419 subjects, for a total of 2,225 subjects. Statistical analyses were performed on completed questionnaires by an independent data analysis company. The net correct response to the two primary communication objectives was 99% among the total population. Responses to questions addressing the use of concurrent medications; types of cholesterol; purpose, dosage, and preparation of the medication; and diet and exercise were also clearly understood. This study showed a high level of comprehension of the purpose and correct use of cholestyramine among both high-school graduates and nongraduates.

Purification and structural characterization of bovine cathelicidins, precursors of antimicrobial peptides

Cathelicidins are a novel family of antimicrobial peptide precursors from mammalian myeloid cells. They are characterized by a conserved N-terminal region while the C-terminal antimicrobial domain can vary considerably in both primary sequence and length. Four cathelicidins, proBac5, proBac7, prododecapeptide and proBMAP-28, have been concurrently purified from bovine neutrophils, using simple and rapid methodologies. The correlation of ES-MS data from the purified proteins with their cDNA-deduced sequences has revealed several common features of their primary sequence, such as the presence of N-terminal 5-oxoproline (pyroglutamate) residues and two disulfide bridges in a 1-2, 3-4 arrangement. The N-terminal domains of the cathelicidins present one or two Asp-Pro bonds, which are particularly acid-labile in proBac5 and proBac7, but stable in prododecapeptide. This suggests that the spatial organization around these bonds may vary in different cathelicidins, and favour hydrolysis in some cases. An unexpected feature of the prododecapeptide is that it exists as dimers formed by three possible combinations of its two isoforms. The isolation of a truncated, monomeric form of this protein, lacking the cysteine-containing antimicrobial dodecapeptide, indicates that dimerization occurs via disulfide bridge formation at the level of the C-terminal domain and that the dodecapeptide is likely released as a dimer from its precursor. Sequence-based secondary structure predictions and CD results indicate for cathelicidins a 30-50% content of extended conformation and <20% content of alpha-helical conformation, with the alpha-helical segment placed near the N-terminus. Finally, similarity searching and topology-based structure prediction underline a significant sequential and structural similarity between the conserved N-terminal domain of cathelicidins and cystatin-like domains, placing this family within the cystatin superfamily. When assayed against cathepsin L, unlike the potent cystatin inhibitors, three of the four cathelicidins show only a poor inhibitory activity (Ki = 0.6-3 microM).

Development of pseudopeptide inhibitors of HIV-1 aspartic protease: analysis and tuning of the subsite specificity

HIV-1 aspartic protease (PR) is a promising target for acquired immunodeficiency syndrome (AIDS) therapy, and the development of PR inhibitors can be accelerated by computer-aided design methods. We describe an approach for the design of new inhibitors, based on the modification of a known reference inhibitor, and the calculation of relative binding energies, taking into account contributions from all species in the binding equilibrium (inhibitor, PR and inhibitor/PR complex), as well as their solvation. This allows for a rational selection of new structures that are likely to have increased inhibition potency. We have analyzed reduced amide bond hexapeptides (Ac-P3-P2-P1-phi[CH2-NH]-P1'-P2-P3'-NH2), based on the structure of the known inhibitor MVT-101. A maximum gain in binding energy (approximately -55 kcal/mol) is observed when Phe or Tyr are present in positions P1 and P1', Glu in position P2' and aromatic residues (Phe, Trp or Tyr) in positions P3 and P3', while, in general, the presence of positively charged residues is destabilizing. This specificity is explained in terms of the interaction of individual inhibitor residues with proximal and distal PR residues. The validity of this computational approach has been confirmed by solid-phase synthesis of several of the designed pseudopeptides, followed by in vitro enzyme inhibition assaying. The best candidate structures show IC50 values in the low nanomolar range.

Cathelicidins: a novel protein family with a common proregion and a variable C-terminal antimicrobial domain

A novel protein family, showing a conserved proregion and a variable C-terminal antimicrobial domain, and named cathelicidin, has been identified in mammalian myeloid cells. The conserved proregion shows sequence similarity to members of the cystatin superfamily of cysteine proteinase inhibitors. Cathelicidins are stored in the cytoplasmic granules of neutrophil leukocytes and release the antimicrobial peptides upon leukocyte activation. Some of these peptides can assume an alpha-helical conformation, others contain one or two disulfide bonds, still others are Pro- and Arg-rich, or Trp-rich. In addition to bacterial killing, some of these peptides exert additional functions related to host defense such as LPS-neutralization and promotion of wound healing.

Molecular cloning of Bac7, a proline- and arginine-rich antimicrobial peptide from bovine neutrophils

Bac7 is a 7 kDa proline- and arginine-rich antimicrobial peptide which was purified from bovine neutrophils. We have used PCR to clone the cDNA of Bac7 precursor, a polypeptide of 21,569 Da. This cDNA is highly conserved in the 5' region, with respect to the corresponding region in the precursors of several other structurally unrelated myeloid antimicrobial peptides. Furthermore, a 148 nt non-coding region at the 3' end is 75% homologous to a corresponding region of the cDNA of the precursor of PR-39, a porcine antibacterial peptide which is also proline- and arginine-rich.

Transforming growth factor-beta: expression in normal and pathological conditions

Expression of the various isoforms of transforming growth factor-beta (TGF-beta) is differentially controlled both in vivo and in vitro. Characterization of the molecular mechanisms governing expression of TGF-beta isoforms now provides a basis for understanding the selective regulation of expression of the TGF-beta s by a variety of factors including oncogenes and tumor suppressor genes. In addition to transcriptional control, data suggest that expression of TGF-beta s is also regulated posttranscriptionally. Regulation of TGF-beta s by steroids and retinoids appears to involve predominantly posttranscriptional mechanisms. Identification of these mechanisms may contribute to the understanding of the regulatory events controlling cellular proliferation and differentiation by TGF-beta s and steroids/retinoids.

Antimicrobial activity of two bactenecins against spirochetes

Bac5 and Bac7 are antimicrobial peptides of bovine neutrophils that act on enteric gram-negative bacteria. We report here that these two peptides immobilize and kill Leptospira interrogans and Leptospira biflexa with MBCs of 6 to 25 micrograms/ml. Conversely, although both peptides bind to Borrelia burgdorferi, the organism is resistant to their action.

Characterization of bovine neutrophil antibacterial polypeptides which bind to Escherichia coli

Bovine neutrophils contain several cationic polypeptides which exert potent microbicidal effects in vitro. To better characterize the repertoire of these polypeptides, we have incubated extracts of bovine neutrophils or neutrophil granules at pH 4 or 7 with either a smooth strain of Escherichia coli or a rough one. Only a few polypeptides interacted with the bacterial surface and were subsequently desorbed with 200 mM MgCl2, as revealed by gel electrophoresis and analysis of Western blots (immunoblots) with appropriate antibodies. Two of the main proteins appearing in Coomassie blue-stained gels have molecular masses of 53 and 15 kDa and correspond to the heavy and light chains of myeloperoxidase. Another prevailing protein band with a molecular mass of 31 kDa was purified and shown to be 87% identical to human azurocidin/CAP37 in its 22-amino-acid N-terminal sequence. Proteins separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and blotted to nitrocellulose did not react with an antiserum to human bactericidal/permeability-increasing protein. Conversely, immunoglobulin G against Bac7 or Bac5, two members of the antimicrobial proline- and arginine-rich polypeptide family, recognized in Western blots both the inactive precursor molecules, proBac7 and proBac5, and the mature polypeptides.

Chemotactic and protease-inhibiting activities of antibiotic peptide precursors

We have recently shown that two antimicrobial peptides (Bac5 and Bac7) and/or their immature forms (proBac5 and proBac7) can be released extracellularly from activated neutrophils. In the present study we have investigated the biological activities of the immature forms, which do not exhibit antimicrobial effects. We show that proBac7 is a monocyte-selective chemoattractant, potentially contributing to the recruitment of these cells to infection sites, whereas proBac5 efficiently inhibits the in vitro activity of cathepsin L, a cysteine proteinase thought to contribute to tissue injury in inflammation.

The cDNA of the neutrophil antibiotic Bac5 predicts a pro-sequence homologous to a cysteine proteinase inhibitor that is common to other neutrophil antibiotics

Bac5 is a 5-kDa proline- and arginine-rich antibiotic, stored as inactive precursor (proBac5) in the large granules of bovine neutrophils. A full-length cDNA encoding the precursor form of Bac5 has been cloned. The encoded protein (pre-proBac5) has a calculated mass of 20,031 Da and a pI of 9.21. This comprises a putative signal peptide of 29 amino acid residues and a 101-residue pro-sequence that precede the mature antibiotic. The pro-sequence is acidic and may neutralize the highly cationic Bac5, thus accounting for the inactivation of the antibiotic activity observed in in vitro experiments. The structure of mature Bac5 agrees closely with the amino acid sequence previously determined, with an additional tripeptide tail predicting carboxyl-terminal amidation. A valyl residue is deduced at the cleavage site for the proteolytic maturation of proBac5, consistent with a previous observation showing elastase as the enzyme involved in this processing step. The region upstream of Bac5 reveals high identity to corresponding regions of two neutrophil antimicrobial polypeptides, CAP18 from rabbit and bovine indolicidin. The COOH-terminal sequences of these antibiotics are completely unrelated. The proregion also exhibits remarkable similarity to pig cathelin, an inhibitor of cathepsin L, indicating a common evolutionary origin.

Treatment of sphingomyelinase deficiency by repeated implantations of amniotic epithelial cells

Five young patients with Niemann-Pick disease type B were treated with repeated implantations of amniotic epithelial cells, as a source of exogenous sphingomyelinase. This treatment abolished the recurrent infections, mainly of the respiratory tract, and led to other improvements of the general conditions of the patients. In particular, we noticed a disappearance of vomiting, a recovery from muscular hypotrophy, and significantly reduced pulmonary distress. In four subjects, who were in a prepuberal state, there was a puberal spurt with a concomitant burst of growth. In two cases, characterized by a greater than normal content of sphingomyelin in urinary sediments, a single implantation caused a sustained normalization of sphingomyelin and total phospholipids in the urine. Finally, sphingomyelinase activity of peripheral leukocytes, when assayed 0.5 to 4 months after some of the implantations, showed a rise to heterozygous values in 30-40% of the assays.

Proteolytic cleavage by neutrophil elastase converts inactive storage proforms to antibacterial bactenecins

Bac5 and Bac7, antibiotics of the bactenecin (proline/arginine-rich peptide) family, are stored as proforms in the large granules of bovine neutrophils [Zanetti, M., Litteri, L., Gennaro, R., Horstmann, H. and Romeo, D. (1990) J. Cell Biol. 111, 1363-1371]. These proforms have been purified to homogeneity from granule extracts by immunoaffinity and reverse-phase chromatography. While mature bactenecins efficiently kill Escherichia coli, Klebsiella pneumoniae and Salmonella typhimurium with minimal inhibitory concentrations of 6-12 micrograms/ml, proBac5 and proBac7 do not affect the growth of the same microorganisms, even at 500 micrograms/ml. Previous investigations have suggested that the conversion of probactenecins into mature antimicrobial peptides is catalyzed by a neutral serine protease stored in the azurophil granules. Purified proBac5 and proBac7 were thus treated with elastase, cathepsin G or proteinase 3, which constitute the pool of neutral serine proteases of the azurophils, and the reaction products were identified by Western blot analysis, mass spectrometry, and N-terminal sequence analysis. Of the three proteases, only elastase is able to catalyze the stepwise cleavage of probactenecins into the corresponding mature peptides, which have the same mass, N-terminal sequence and antibiotic activity of authentic Bac5 and Bac7. These results point to the importance of cooperation between azurophils and large granules in mounting a defense reaction.