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Consensus-based framework for evaluating data modernization initiatives: the case of cancer registration and electronic reporting. JAMIA Open 2023; 6:ooad060. [PMID: 37638125 PMCID: PMC10448993 DOI: 10.1093/jamiaopen/ooad060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Revised: 05/16/2023] [Accepted: 07/24/2023] [Indexed: 08/29/2023] Open
Abstract
As part of its data modernization initiative (DMI), the Centers for Disease Control and Prevention, Division of Cancer Prevention and Control is testing and implementing innovative solutions to improve cancer surveillance data quality and timeliness. We describe a consensus-based effort to create a framework to guide the evaluation of cancer surveillance modernization efforts by addressing specific context, processes, and costs related to cancer registration. We drew on prior theories, consulted with experts, and sought feedback from cancer registry staff. We developed the cancer surveillance systems, context, outcomes, and process evaluation (CS-SCOPE) framework to explain the ways in which cancer registry data quality, timeliness, and efficiency are impacted by external and internal contextual factors and interrelated process and content factors. The framework includes implementation measures to understand acceptability of process changes along with outcome measures to assess DMI initiation and ongoing sustainability. The framework's components and structures can be tailored for use in other DMI evaluations.
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Operational Characteristics of Central Cancer Registries that Support the Generation of High-Quality Surveillance Data. JOURNAL OF REGISTRY MANAGEMENT 2022; 49:10-16. [PMID: 36968178 PMCID: PMC10036081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 03/29/2023]
Abstract
Objectives We aim to assess external and internal attributes and operations of the Centers for Disease Control and Prevention (CDC)'s National Program of Cancer Registries (NPCR) central cancer registries by their consistency in meeting national data quality standards. Methods The NPCR 2017 Program Evaluation Instrument (PEI) data were used to assess registry operational attributes, including adoption of electronic reporting, compliance with reporting, staffing, and software used among 46 NPCR registries. These factors were stratified by (1) registries that met the NPCR 12-month standards for all years 2014-2017; (2) registries that met the NPCR 12-month standards at least once in 2014-2017 and met the NPCR 24-month standards for all years 2014-2017; and (3) registries that did not meet the NPCR 24-month standards for all years 2014-2017. Statistical tests helped identify significant differences among registries that consistently, sometimes, or seldom/never achieved data standards. Results Registries that always met the standards had a higher level of electronic reporting and a higher compliance with reporting among hospitals than registries that sometimes or seldom/never met the standards. Although not a statistically significant finding, the same registries also had a higher proportion of staffing positions filled, a higher proportion of certified tumor registrars, and more quality assurance and information technology staff. Conclusions This information may be used to understand the importance of various factors and characteristics, including the adoption of electronic reporting, that may be associated with a registry's ability to consistently meet NPCR standards. The findings may be helpful in identifying best practices for processing high-quality cancer data.
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Pursuing Data Modernization in Cancer Surveillance by Developing a Cloud-Based Computing Platform: Real-Time Cancer Case Collection. JCO Clin Cancer Inform 2021; 5:24-29. [PMID: 33411623 DOI: 10.1200/cci.20.00082] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cancer surveillance is a field focused on collection of data to evaluate the burden of cancer and apply public health strategies to prevent and control cancer in the community. A key challenge facing the cancer surveillance community is the number of manual tasks required to collect cancer surveillance data, thereby resulting in possible delays in analysis and use of the information. To modernize and automate cancer data collection and reporting, the Centers for Disease Control and Prevention is planning, developing, and piloting a cancer surveillance cloud-based computing platform (CS-CBCP) with standardized electronic reporting from laboratories and health-care providers. With this system, automation of the cancer case collection process and access to real-time cancer case data can be achieved, which could not be done before. Furthermore, the COVID-19 pandemic has illustrated the importance of continuity of operations plans, and the CS-CBCP has the potential to provide such a platform suitable for remote operations of central cancer registries.
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Population Heath Informatics Can Advance Interoperability: National Program of Cancer Registries Electronic Pathology Reporting Project. JCO Clin Cancer Inform 2020; 4:985-992. [PMID: 33125274 PMCID: PMC7608601 DOI: 10.1200/cci.20.00098] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/30/2020] [Indexed: 01/31/2023] Open
Abstract
PURPOSE Given the reach, breadth, and volume of data collected from multiple clinical settings and systems, US central cancer registries (CCRs) are uniquely positioned to test and advance cancer health information exchange. This article describes a current Centers for Disease Control and Prevention (CDC) National Program of Cancer Registries (NPCR) cancer informatics data exchange initiative. METHODS CDC is using an established cloud-based platform developed by the Association of Public Health Laboratories (APHL) for national notifiable disease reporting to enable direct transmission of standardized electronic pathology (ePath) data from laboratories to CCRs in multiple states. RESULTS The APHL Informatics Messaging Services (AIMS) Platform provides an infrastructure to enable a large national laboratory to submit data to a single platform. State health departments receive data from the AIMS Platform through a secure portal, eliminating separate data exchange routes with each CCR. CONCLUSION Key factors enabling ePath data exchange from laboratories to CCRs are having established cancer registry data standards and using a single platform/portal to reduce data streams. NPCR plans to expand this approach in alignment with ongoing cancer informatics efforts in clinical settings. The 50 CCRs supported by NPCR provide a variety of scenarios to develop and disseminate cancer data informatics initiatives and have tremendous potential to increase the implementation of cancer data exchange.
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Using informatics to improve cancer surveillance. J Am Med Inform Assoc 2020; 27:1488-1495. [PMID: 32941600 PMCID: PMC7647312 DOI: 10.1093/jamia/ocaa149] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 05/19/2020] [Accepted: 06/19/2020] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVES This review summarizes past and current informatics activities at the Centers for Disease Control and Prevention National Program of Cancer Registries to inform readers about efforts to improve, standardize, and automate reporting to public health cancer registries. TARGET AUDIENCE The target audience includes cancer registry experts, informaticians, public health professionals, database specialists, computer scientists, programmers, and system developers who are interested in methods to improve public health surveillance through informatics approaches. SCOPE This review provides background on central cancer registries and describes the efforts to standardize and automate reporting to these registries. Specific topics include standardized data exchange activities for physician and pathology reporting, software tools for cancer reporting, development of a natural language processing tool for processing unstructured clinical text, and future directions of cancer surveillance informatics.
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Cancer collection efforts in the United States provide clinically relevant data on all primary brain and other CNS tumors. Neurooncol Pract 2019; 6:330-339. [PMID: 31555447 DOI: 10.1093/nop/npz029] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Cancer surveillance is critical for monitoring the burden of cancer and the progress in cancer control. The accuracy of these data is important for decision makers and others who determine resource allocation for cancer prevention and research. In the United States, cancer registration is conducted according to uniform data standards, which are updated and maintained by the North American Association of Central Cancer Registries. Underlying cancer registration efforts is a firm commitment to ensure that data are accurate, complete, and reflective of current clinical practices. Cancer registries ultimately depend on medical records that are generated for individual patients by clinicians to record newly diagnosed cases. For the cancer registration of brain and other CNS tumors, the Central Brain Tumor Registry of the United States is the self-appointed guardian of these data. In 2017, the Central Brain Tumor Registry of the United States took the initiative to promote the inclusion of molecular markers found in the 2016 WHO Classification of Tumours of the Central Nervous System into information collected by cancer registries. The complexities of executing this latest objective are presented according to the cancer registry standard-setting organizations whose collection practices for CNS tumors are directly affected.
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Natural language processing systems for capturing and standardizing unstructured clinical information: A systematic review. J Biomed Inform 2017; 73:14-29. [PMID: 28729030 DOI: 10.1016/j.jbi.2017.07.012] [Citation(s) in RCA: 259] [Impact Index Per Article: 37.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Revised: 06/07/2017] [Accepted: 07/14/2017] [Indexed: 12/24/2022]
Abstract
We followed a systematic approach based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses to identify existing clinical natural language processing (NLP) systems that generate structured information from unstructured free text. Seven literature databases were searched with a query combining the concepts of natural language processing and structured data capture. Two reviewers screened all records for relevance during two screening phases, and information about clinical NLP systems was collected from the final set of papers. A total of 7149 records (after removing duplicates) were retrieved and screened, and 86 were determined to fit the review criteria. These papers contained information about 71 different clinical NLP systems, which were then analyzed. The NLP systems address a wide variety of important clinical and research tasks. Certain tasks are well addressed by the existing systems, while others remain as open challenges that only a small number of systems attempt, such as extraction of temporal information or normalization of concepts to standard terminologies. This review has identified many NLP systems capable of processing clinical free text and generating structured output, and the information collected and evaluated here will be important for prioritizing development of new approaches for clinical NLP.
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TAK-228 (formerly MLN0128), an investigational dual TORC1/2 inhibitor plus paclitaxel, with/without trastuzumab, in patients with advanced solid malignancies. Cancer Chemother Pharmacol 2017; 80:261-273. [PMID: 28601972 DOI: 10.1007/s00280-017-3343-4] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Accepted: 05/20/2017] [Indexed: 11/28/2022]
Abstract
PURPOSE This phase I trial evaluated the safety, pharmacokinetic profile, and antitumor activity of investigational oral TORC1/2 inhibitor TAK-228 plus paclitaxel, with/without trastuzumab, in patients with advanced solid malignancies. METHODS Sixty-seven patients received TAK-228 6-40 mg via three dosing schedules; once daily for 3 days (QDx3d QW) or 5 days per week (QDx5d QW), and once weekly (QW) plus paclitaxel 80 mg/m2 (dose-escalation phase, n = 47) and with/without trastuzumab 2 mg/kg (expansion phase, n = 20). Doses were escalated using a modified 3 + 3 design, based upon dose-limiting toxicities in cycle 1. RESULTS TAK-228 pharmacokinetics exhibited dose-dependent increase in exposure when dosed with paclitaxel and no apparent differences when administered with or 24 h after paclitaxel. Dose-limiting toxicities were dehydration, diarrhea, stomatitis, fatigue, rash, thrombocytopenia, neutropenia, leukopenia, and nausea. The maximum tolerated dose of TAK-228 was determined as 10-mg QDx3d QW; the expansion phase proceeded with 8-mg QDx3d QW. Overall, the most common grade ≥3 drug-related toxicities were neutropenia (21%), diarrhea (12%), and hyperglycemia (12%). Of 54 response-evaluable patients, eight achieved partial response and six had stable disease lasting ≥6 months. CONCLUSION TAK-228 demonstrated a safety profile consistent with other TORC inhibitors and promising preliminary antitumor activity in a range of tumor types; no meaningful difference was noted in the pharmacokinetics of TAK-228 when administered with or 24 h after paclitaxel. These findings support further investigation of TAK-228 in combination with other agents including paclitaxel, with/without trastuzumab, in patients with advanced solid tumors. CLINICALTRIALS. GOV IDENTIFIER NCT01351350.
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Abstract P5-14-04: A phase 2 study evaluating orteronel, an inhibitor of androgen biosynthesis, in patients with androgen receptor (AR)-expressing metastatic breast cancer: Interim analysis. Cancer Res 2016. [DOI: 10.1158/1538-7445.sabcs15-p5-14-04] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Background: The frequency of AR expression varies in the different breast cancer subtypes with 88%, 59%, and 32% expression reported in ER+, HER2+, and triple negative tumors, respectively. AR expression is associated with resistance to endocrine therapy in ER+ breast cancer. Androgen levels frequently increase following treatment with aromatase inhibitors suggesting a role for androgen synthesis inhibitors in ER+ breast cancer. AR signaling and expression are seen in triple negative breast cancer (TNBC), and a distinct AR TNBC subtype can be identified by gene expression profiling. AR expression in TNBC offers a potential therapeutic target. Preclinical and clinical studies demonstrated anti-androgen agent activity in breast cancer cell lines; preliminary clinical data suggests activity in TNBC. Orteronel is a novel, oral, selective, nonsteroidal inhibitor of 17, 20-lyase, a key enzyme in androgen biosynthesis that is being evaluated as endocrine therapy in various hormone-sensitive cancers. In this phase 2 study we are evaluating single agent orteronel in AR+ MBC.
Methods: Pts with AR expressing MBC (≥10% staining by central immunohistochemistry) were eligible. Pts were grouped into 2 cohorts for analysis: Cohort 1-TNBC and Cohort 2-ER+ (HER2 could be +/- in this cohort). Pts must have been previously treated with standard therapy for MBC (1-3 chemotherapy regimens for TNBC, 1-3 hormonal therapies + 1 chemotherapy for ER+ patients, ≥2 HER2-targeted regimens for HER2+ patients). A 6 pt lead-in for safety and tolerability of orteronel in AR+ female MBC pts was followed by open enrollment to either cohort. All pts received 300 mg orteronel PO BID over a 4 week cycle and underwent response assessment every 2 cycles. Treatment was continued until disease progression or unacceptable toxicity. The hypothesized response rate for Cohort 1 was 10% and 13% for Cohort 2. We present the results of a protocol-specified interim analysis of the ER+ MBC pts (Cohort 2).
Results: From 3/2014 to 4/2015, a total of 29 pts were enrolled on cohort 2. Median age was 65 years (range, 39-79); 90% ECOG ≤1; 90% HER2-/10% HER2+; median of 7 prior therapies (range 3-11). 93% had prior chemotherapy. Pts received a median of 2 cycles of orteronel treatment (range 1-4) and 3 pts (10%) are still on treatment. Of the 26 pts (90%) pts that have discontinued, 19 (66%) discontinued due to disease progression, 4 (14%) due to pt decision, 2 (7%) due to adverse event (AE), and 1 (3%) due to non-compliance. The most common treatment-related G 3/4 AEs were increased lipase [3 pts (10%)] and hypertension [2 pts (7%)]. There were no treatment-related SAEs or deaths on study. Three pts (10%) had stable disease as their best response. Further response evaluation is underway.
Conclusions: Orteronel monotherapy was well tolerated but appears to have limited single-agent activity in this heavily pre-treated ER+ MBC pt population. The full results from this interim analysis will be presented.
Citation Format: Yardley DA, Peacock N, Young RR, Silber A, Chung G, Webb CD, Jones SF, Shastry M, Midha R, DeBusk LM, Hainsworth JD, Burris HA. A phase 2 study evaluating orteronel, an inhibitor of androgen biosynthesis, in patients with androgen receptor (AR)-expressing metastatic breast cancer: Interim analysis. [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 P5-14-04.
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A phase IB trial of the oral MEK inhibitor trametinib (GSK1120212) in combination with everolimus in patients with advanced solid tumors. Ann Oncol 2015; 26:58-64. [PMID: 25344362 DOI: 10.1093/annonc/mdu482] [Citation(s) in RCA: 96] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
BACKGROUND This phase Ib trial investigated the safety, tolerability, and recommended phase II dose and schedule of the MEK inhibitor trametinib in combination with the mammalian target of rapamycin (mTOR) inhibitor everolimus. Secondary objectives included pharmacokinetic (PK) characterization and evaluation of clinical activity. PATIENTS AND METHODS A total of 67 patients with advanced solid tumors were enrolled in this open-label, single-arm, dose-escalation study. Dose escalation followed a 3 + 3 design. Patients were assigned to one of 10 different cohorts, involving either daily dosing with both agents or daily dosing with trametinib and intermittent everolimus dosing. This included an expansion cohort comprising patients with pancreatic tumors. PKs samples were collected predose, as well as 1, 2, 4, and 6 h post-dose on day 15 of the first treatment cycle. RESULTS Concurrent treatment with trametinib and everolimus resulted in frequent treatment-related adverse events, including mucosal inflammation (40%), stomatitis (25%), fatigue (54%), and diarrhea (42%). PK assessment did not suggest drug-drug interactions between these two agents. Of the 67 enrolled patients, 5 (7%) achieved partial response (PR) to treatment and 21 (31%) displayed stable disease (SD). Among the 21 patients with pancreatic cancer, PR was observed in 1 patient (5%) and SD in 6 patients (29%). CONCLUSIONS This study was unable to identify a recommended phase II dose and schedule of trametinib in combination with everolimus that provided an acceptable tolerability and adequate drug exposure.
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Implementation of the National Breast and Cervical Cancer Early Detection Program: the beginning. Cancer 2014; 120 Suppl 16:2540-8. [PMID: 25099896 DOI: 10.1002/cncr.28820] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Revised: 03/07/2014] [Accepted: 03/10/2014] [Indexed: 11/10/2022]
Abstract
In 1990, Congress passed the Breast and Cervical Cancer Mortality Prevention Act because of increases in the number of low-income and uninsured women being diagnosed with breast cancer. This act authorized the Centers for Disease Control and Prevention (CDC) to establish the National Breast and Cervical Cancer Early Detection Program (NBCCEDP) to provide high-quality and timely breast and cervical cancer screening and diagnostic services to low-income, uninsured women. The program started in 1991, and, in 1993, Congress amended the act to allow the CDC to fund American Indian and Alaska Native tribes and tribal organizations. By 1996, the program was providing cancer screening across the United States. To ensure appropriate delivery and monitoring of services, the program adopted detailed policies on program management, evidence-based guidelines for clinical services, a systematized clinical data system to track service quality, and key partnerships that expand the program's reach. The NBCCEDP currently funds 67 programs, including all 50 states, the District of Columbia, 5 US territories, and 11 tribes or tribal organizations.
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Abstract P5-06-06: The Safety and Tolerability of Panobinostat (LBH589) in Combination with Capecitabine +/− Lapatinib: A Phase I Study in HER2+ Breast Cancer. Cancer Res 2010. [DOI: 10.1158/0008-5472.sabcs10-p5-06-06] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Background: Panobinostat is a histone deacetylase (HDAC) inhibitor, for which in vitro studies have suggested activity in breast cancer lines. This phase I study was designed to assess the safety, tolerability, and efficacy of panobinostat in combination with lapatinib and capecitabine in 3 parts. Part 1, for which we have previously reported findings (Peacock et al, ASCO 2010), established the maximum tolerated dose (MTD) of panobinostat (30mg twice weekly) in combination with capecitabine (1000mg/m2 BID). Part 2, reported here, was designed to assess the QTc prolongation and overall toxicity of panobinostat in combination with lapatinib in patients with HER2+ breast cancer. Part 3 will assess the tolerability and efficacy of the triplet combination based on doses defined in Parts 1 and 2. Method: Patients aged ≥18 years with incurable, locally recurrent or metastatic HER2+ breast cancer were eligible. Additional eligibility criteria included: < 3 prior treatments in the metastatic setting; ECOG PS 0-1; measurable disease by RECIST; no impairment of cardiac function; no prior treatment with HDAC inhibitors; informed consent. Lapatinib doses of 1000mg daily were administered with panobinostat doses of 15mg and 20mg three times weekly, following 1 week of 2 doses of panobinostat alone to assess QTc prolongation. Cycles were repeated every 21 days until disease progression or toxicity warranted drug discontinuation. Patients were reevaluated for response every 2 cycles.
Results: 5 female patients with HER2+ metastatic breast cancer were accrued to Part 2, with a median age of 66 years (range: 64 — 67); 80% of patients were ECOG PS 0. To date, patients have received 17 cycles of treatment (median 4 cycles), and 2 patients have stable disease (progression1, unevaluable 1, and too early to assess 1), with one patient remaining on treatment. There have been no dose-limiting toxicities. One patient was hospitalized for grade 3 peripheral neuropathy (unrelated). No grade 2/3/4 toxicities have occurred in >1 patient; no QTc prolongation has been observed.
Conclusions: Our preliminary findings suggest that the combination of panobinostat and lapatinib is safe and tolerable. No QTc prolongation or cardiotoxicity has been observed. Part 3 will evaluate the triplet combination using the dosages established in Parts 1 and 2.
Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P5-06-06.
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PRIMARY SARCOMA OF THE LOWER END OF THE FEMUR INVOLVING THE SYNOVIAL MEMBRANE: WITH A CRITICAL REVIEW OF THE LITERATURE OF SYNOVIAL SARCOMA REPORT OF ONE CASE WITH COMPLETE PATHOLOGICAL AND RADIOGRAPHIC EXAMINATION. Ann Surg 2007; 60:440-50. [PMID: 17863247 PMCID: PMC1406584 DOI: 10.1097/00000658-191410000-00002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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The mechanics of landing when stepping down in unilateral lower-limb amputees. Clin Biomech (Bristol, Avon) 2006; 21:184-93. [PMID: 16274904 DOI: 10.1016/j.clinbiomech.2005.09.015] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2005] [Revised: 09/01/2005] [Accepted: 09/27/2005] [Indexed: 02/07/2023]
Abstract
BACKGROUND The ability to successfully negotiate stairs and steps is an important factor for functional independence. While work has been undertaken to understand the biomechanics of gait in lower-limb amputees, little is known about how amputees negotiate stairs and steps. This study aimed to determine the mechanics of landing in unilateral lower-limb amputees when stepping down to a new level. A secondary aim was to assess the effects of using a shank-mounted shock-absorbing device (Tele-Torsion Pylon) on the mechanics of landing. METHODS Ten unilateral amputees (five transfemoral and five transtibial) and eight able-bodied controls performed single steps down to a new level (73 and 219 mm). Trials were repeated in amputees with the Tele-Torsion Pylon active and inactive. The mechanics of landing were evaluated by analysing peak limb longitudinal force, maximal limb shortening, lower extremity stiffness, and knee joint angular displacement during the initial contact period, and limb and ankle angle at the instant of ground-contact. Data were collected using a Vicon 3D motion analysis system and two force platforms. FINDINGS Amputees landed on a straightened and near vertical limb. This limb position was maintained in transfemoral amputees, whereas in transtibial amputees knee flexion occurred. As a result lower extremity stiffness was significantly greater in transfemoral amputees compared to transtibial amputees and able-bodied controls (P<0.001). The Tele-Torsion Pylon had little effect on the mechanics of landing in transtibial amputees, but brought about a reduction in lower extremity stiffness in transfemoral amputees (P<0.05). INTERPRETATION Amputees used a stepping strategy that ensured the direction of the ground reaction force vector was kept anterior of the knee joint centre. Using a Tele-Torsion Pylon may improve the mechanics of landing during downward stepping in transfemoral amputees.
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The gait initiation process in unilateral lower-limb amputees when stepping up and stepping down to a new level. Clin Biomech (Bristol, Avon) 2005; 20:405-13. [PMID: 15737448 DOI: 10.1016/j.clinbiomech.2004.11.018] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2004] [Revised: 11/25/2004] [Accepted: 11/26/2004] [Indexed: 02/07/2023]
Abstract
BACKGROUND Unilateral lower-limb amputees lead with their intact limb when stepping up and with their prosthesis when stepping down; the gait initiation process for the different stepping directions has not previously been investigated. METHODS Ten unilateral amputees (5 transfemoral and 5 transtibial) and 8 able-bodied controls performed single steps up and single steps down to a new level (73 and 219 mm). Duration, a-p and m-l centre of mass and centre of pressure peak displacements and centre of mass peak velocity of the anticipatory postural adjustment and step execution phase were evaluated for each stepping direction by analysing data collected using a Vicon 3D motion analysis system. FINDINGS There were significant differences (in the phase duration, peak a-p and m-l centre of pressure displacement and peak a-p and m-l centre of mass velocity at heel-off and at foot-contact) between both amputee sub-groups and controls (P<0.05), but not between amputee sub-groups. These group differences were mainly a result of amputees adopting a different gait initiation strategy for each stepping direction. INTERPRETATION Findings indicate the gait initiation process utilised by lower-limb amputees was dependent on the direction of stepping and more particularly by which limb the amputee led with; this suggests that the balance and postural control of gait initiation is not governed by a fixed motor program, and thus that becoming an amputee will require time and training to develop alternative neuromuscular control and coordination strategies. These findings should be considered when developing training/rehabilitation programs.
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The 'redefinition of death' debate: western concepts and western bioethics. SCIENCE AND ENGINEERING ETHICS 2001; 7:63-75. [PMID: 11214385 DOI: 10.1007/s11948-001-0024-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Biomedicine is a global enterprise constructed upon the belief in the universality of scientific truths. However, despite huge scientific advances over recent decades it has not been able to formulate a specific and universal definition of death: In fact, in its attempt to redefine death, the concept of death appears to have become immersed in ever increasing vagueness and ambiguity. Even more worrisome is that bioethics, in the form of principlism, is also endeavouring to become a global enterprise by claiming neutrality. It appears that the discourse within both disciplines have similarly manipulated the boundaries of death to include the "dying". This paper argues that the redefinition of death debate in biomedicine reveals a concept of personhood which is profoundly western in origin and which is in accordance to the concept adhered to within principlism. Biomedicine and bioethics do not appear to acknowledge the limitations of their own world view and hence lack an understanding of their applicability and appropriateness in diverse social and cultural contexts; a situation which adds credence to claims as to the hegemonic and imperialistic nature of all such global enterprises.
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A phase I trial of vinorelbine in combination with mitoxantrone in patients with refractory solid tumors. Invest New Drugs 1998; 16:37-43. [PMID: 9740542 DOI: 10.1023/a:1016075126007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Vinorelbine (Navelbine) is a unique semi-synthetic vinca-alkaloid with a favorable safety profile that has demonstrated significant antitumor activity in patients with non-small cell lung cancer, advanced breast cancer, advanced ovarian cancer and Hodgkin's disease. The most common dose-limiting toxicity is neutropenia, while other reported toxicities are minimal. Mitoxantrone (Novantrone) is an anthracene derivative that has demonstrated antitumor activity in patients with breast cancer, ovarian cancer, acute leukemia, and lymphoma. Mitoxantrone also has a very favorable toxicity profile with significantly less nausea and vomiting, alopecia, and stomatitis as compared with anthracyclines. The dose-limiting toxicity for mitoxantrone is leukopenia. The study was designed to determine the safety and maximally tolerated dose of IV vinorelbine used in combination with a fixed dose of mitoxantrone for the treatment of patients with refractory solid tumors. Vinorelbine was administered on days 1 and 8 of the treatment regimen as a short IV infusion. The starting dose was 15 mg/m2. Mitoxantrone was administered as a 20-min infusion on day 1 only at a fixed dose of 10 mg/m2. Seventeen patients with solid malignancies were entered in the study. For personal reasons, one patient decided to discontinue the treatment after day 1 of cycle 1. Therefore, 16 patients were evaluable for toxicity. The main toxicity was myelosuppression which was dose-limiting and resulted in dose reductions and delays. The use of G-CSF had a minimal overall impact on this regimen. Stable disease was observed in three cases. In patients previously treated with chemotherapy, the maximally tolerated dose was defined as vinorelbine 20 mg/m2 on days 1 and 8 and mitoxantrone 10 mg/m2 on day 1 without growth factor support. These doses can be recommended for phase II study of the regimen as salvage treatment.
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Abstract
Orofacial granulomatosis is a condition that may be difficult to diagnose for those unfamiliar with the entity. This paper describes two cases and addresses the presentation, pathogenesis and treatment. The clinical recognition of this condition is important as is the subsequent investigation by an appropriate specialist. Management of patients needs to take into account the results of further investigations, the patient's expectations, and the severity of the condition.
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Abstract
OBJECTIVE To review the chemistry, pharmacology, pharmacokinetics, clinical activity, adverse effects, and dosage and administration guidelines for vinorelbine in the treatment of non-small-cell lung cancer (NSCLC). DATA SOURCES A MEDLINE search (1989-1995) using the terms vinorelbine and Navelbine was conducted. Additional unpublished data were provided by Glaxo Wellcome Drug Information. STUDY SELECTION AND DATA EXTRACTION The articles chosen for inclusion all appeared in peer-reviewed journals. Pertinent abstracts, as judged by the authors, were also included. DATA SYNTHESIS Vinorelbine is a new semisynthetic vinca alkaloid approved by the Food and Drug Administration for the first-line treatment of patients with advanced NSCLC. The drug demonstrated a broad spectrum of antitumor activity in preclinical studies and produced dose-limiting neutropenia in Phase I trials. In Phase II studies, an overall response rate of approximately 30% was reported with single-agent vinorelbine. Furthermore, in large, multicenter, randomized Phase III trials, treatment with vinorelbine alone and in combination with cisplatin resulted in improved survival compared with controls. The drug was well tolerated, with granulocytopenia being the most commonly reported adverse effect. However, the incidence of fever and hospitalization associated with this granulocytopenia was exceptionally low. The recommended dose is 30 mg/m2 weekly administered by intravenous injection or infusion. CONCLUSIONS As no specific chemotherapy regimen has previously been regarded as standard therapy for advanced NSCLC, vinorelbine is a promising new treatment for this patient population. It has been shown in several randomized, controlled trials to increase survival without compromising quality of life.
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Topoisomerase I inhibitors: topotecan and irinotecan. CANCER PRACTICE 1996; 4:51-3. [PMID: 8788772] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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Air embolism from needle-less infusion ports. THE NEW ZEALAND MEDICAL JOURNAL 1995; 108:280. [PMID: 7637935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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Evaluation of intravenous ketorolac administered by bolus or infusion for treatment of postoperative pain. A double-blind, placebo-controlled, multicenter study. Anesthesiology 1994; 80:1277-86. [PMID: 8010474 DOI: 10.1097/00000542-199406000-00015] [Citation(s) in RCA: 94] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
BACKGROUND Ketorolac is a nonsteroidal analgesic that may provide postoperative analgesia without opioid-related side effects. This double-blind, randomized, multicenter study evaluated the analgesic efficacy and safety of intravenous ketorolac in 207 patients during the first 24 h after major surgery. METHODS Subjects were assigned to receive one of three analgesic regimens: a ketorolac infusion, ketorolac boluses, or placebo. All subjects had access to intravenous morphine via patient-controlled analgesia (PCA). Evaluations included PCA morphine used, pain assessment (categorical pain intensity scores and visual analogue pain scores), pain relief (categorical pain relief scores), sedation, presence of adverse events, and overall rating of regimens by study observers and patients. RESULTS Patients in the ketorolac infusion group (but not the ketorolac bolus group) used less morphine (average 33 mg) than did the placebo group (44 mg) (P = 0.009). Significant differences favoring both ketorolac groups were seen in the pain intensity and the categorical pain relief scores at various time points during the study. At the termination of the study, compared with the placebo group, categorical pain intensity scores were lower in the ketorolac bolus group; visual analogue pain scores were lower in both ketorolac groups; and pain relief scores were higher in the ketorolac bolus group. The incidence of vomiting was significantly greater in the placebo group (27%) than in the ketorolac infusion group (12%) or bolus group (9%) (P = 0.032 and P = 0.005, respectively). The incidence of postoperative fever was 10% in the ketorolac bolus group and 25% in the placebo group (P = 0.013). Study observers noted less nursing difficulty while caring for patients in the ketorolac infusion group (P = 0.015). Study observers and patients in both ketorolac groups reported statistically significant overall drug superiority compared with placebo. CONCLUSIONS It is concluded that intravenous boluses or infusions of ketorolac in conjunction with PCA morphine provide effective, safe analgesia after major surgery and improve on the response to PCA morphine alone.
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NSAIDs. Can J Anaesth 1994; 41:548-9. [PMID: 8069998 DOI: 10.1007/bf03011554] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
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Ketorolac and renal impairment. Anaesth Intensive Care 1994; 22:113-4. [PMID: 7909207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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The OSHA bloodborne pathogens standard. AAOHN JOURNAL : OFFICIAL JOURNAL OF THE AMERICAN ASSOCIATION OF OCCUPATIONAL HEALTH NURSES 1993; 41:218. [PMID: 8390264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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Abstract
The analgesic efficacy of single doses of oral morphine sulphate solution (10 mg) and ibuprofen 600 mg was compared in 12 volunteers using a double-blind, double-dummy, placebo-controlled design on the cold pressor experimental pain model. Measurement of pain intensity was made before medication and then at 30, 60, 90, 120 and 180 min; blood samples were taken at these times for measurement of morphine and glucuronide metabolites by radioimmunoassay. Sessions were at least 5 days apart. Correlations were sought between analgesic effect and plasma concentrations of either morphine or morphine-6-glucuronide. Morphine produced significant reduction in both peak pain intensity and area under the pain intensity curve compared with placebo; the threshold time was significantly increased by morphine compared with placebo. Ibuprofen was statistically indistinguishable from placebo on all three measures of analgesia. Analgesic effect and plasma concentrations of morphine showed significant correlation (P = 0.053). The study confirmed reports of the opiate sensitivity of the cold pressor model, and the apparent insensitivity of the model to non-steroidal anti-inflammatory drugs.
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Analgesia following femoral neck surgery. Lateral cutaneous nerve block as an alternative to narcotics in the elderly. Anaesthesia 1985; 40:682-5. [PMID: 3896019 DOI: 10.1111/j.1365-2044.1985.tb10952.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
In a prospective controlled randomised trial on patients undergoing operative repair of fractured neck of femur via a lateral incision, the postoperative analgesic requirements of one group of patients who received a lateral cutaneous nerve block were compared with a second group who received no block. The former group were found to need significantly less intramuscular pethidine in the first 24 hours, and 44% required no supplementary analgesia whatsoever during this period. The time to first dose of opioid in the remainder was greatly increased. No untoward sequelae associated with the nerve block were seen.
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Abstract
1. Miniature end-plate potentials (m.e.p.p.s) were intra- and extracellularly recorded from neuromuscular junctions in rat phrenic nerve-diaphragm preparations in vitro.2. Statistical analysis of the intervals between m.e.p.p.s showed that when the mean number of events in time t was plotted as a function of the variance of the events in time t there was a significant deviation from the straight line relationship expected for a Poisson process. Computer simulation showed that this deviation is explicable if release was generated by the random phasing of the activity of a number of releasing sites.3. There was no indication that release of one quantum influences the probability of release of remaining quanta (drag, clustering). It is suggested that m.e.p.p.s whose amplitude is larger than the mode result from the release of the contents of vesicles whose volume is also supramodal.4. The effects of depolarization of nerve terminals upon the variance-mean curve suggest an increase in the activity of sites rather than an increase in their number.5. Statistical analysis indicated at least 200 +/- 100 (mean +/- 1 S.E.) releasing sites. This number is of the same order as the number of sites of vesicle aggregation and presynaptic membrane density seen in electron micrographs of nerve terminals of this preparation.
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The effect of temperature change upon transmitter release, facilitation and post-tetanic potentiation. J Physiol 1971; 216:591-609. [PMID: 4327694 PMCID: PMC1331924 DOI: 10.1113/jphysiol.1971.sp009542] [Citation(s) in RCA: 126] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
1. End-plate potentials (e.p.p.s) and miniature end-plate potentials (m.e.p.p.s) were intracellularly recorded from rat diaphragm phrenic nerve preparations in vitro at temperatures between 7 degrees and 40 degrees C.2. The quantal content of e.p.p.s and the frequency of m.e.p.p.s showed broadly similar relationships with temperature, with maxima about 20 degrees and above 39 degrees C.3. Analysis of the change in e.p.p. quantal content showed that the maximum about 20 degrees C was accompanied by a similar maximum of p, the probability of release of quanta. The maximum above 39 degrees C was associated with a rise in n, a presynaptic store of material needed for release.4. The rate at which transmitter could be mobilized was linear in an Arrhenius plot with an apparent activation energy of 25 kcal deg(-1).5. Facilitation and post-tetanic potentiation (PTP) were shown to be entirely attributable to changes in p.6. It is suggested that facilitation and PTP have a common basis and that the (temperature-dependent) rate of Ca removal from intracellular sites at which it exerts its action is as important a determinant of the magnitude of quantal release as is the amount of Ca combining with these sites.
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Abstract
Guinea-pigs were immunized with antigen prepared from calf thymus and muscle, and from guinea-pig thymus, and rats were immunized with antigen prepared from rat thymus and rat muscle. There was an increased incidence of delayed hypersensitivity and circulating thymus antibodies in the immunized guinea-pigs and an increased incidence of thymitis in the immunized guinea-pigs and rats. However, when compared with control animals, there was no electrophysiological evidence of impairment of neuromuscular transmission in the immunized animals.
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The effects of nerve stimulation and hemicholinium on synaptic vesicles at the mammalian euromuscular junction. J Physiol 1970; 207:31-50. [PMID: 5503879 PMCID: PMC1348690 DOI: 10.1113/jphysiol.1970.sp009046] [Citation(s) in RCA: 129] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
1. Electron micrographs of nerve terminals in rat phrenic nerve-diaphragm preparations have been studied. This has been done before and after prolonged nerve stimulation. The effectiveness of nerve stimulation has been monitored by intracellular micro-electrode recordings from the muscle cells.2. Characteristic changes in the form and distribution of the nerve terminal mitochondria were noted after nerve stimulation.3. Synaptic vesicle numbers in the region of nerve terminal less than 1800 A from the synaptic cleft were significantly greater in tissue taken 2 and 3 min after nerve stimulation, than in unstimulated preparations.4. The long and short diameters of the synaptic vesicle profiles less than 1800 A from the synaptic cleft were measured. Analysis of the distribution of the diameters indicated synaptic vesicles to be basically spherical structures. Estimates of synaptic vesicle volume were made from the measurements. Synaptic vesicle volume was significantly reduced in tissue taken 2 and 4 min following nerve stimulation.5. If hemicholinium, a compound which inhibits acetylcholine synthesis, was present during the period of nerve stimulation, much greater reductions in synaptic vesicle volume occurred. Synaptic vesicle numbers in the region of nerve terminal less than 1800 A from the synaptic cleft were also reduced, compared with unstimulated control preparations.6. These results are regarded as support for the hypothesis that the synaptic vesicles in nerve terminals at the mammalian neuromuscular junction represent stores of the transmitter substance, acetylcholine.
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Some effects of nerve stimulation andhemicholinium on quantal transmitter release at the mammalian neuromuscular junction. J Physiol 1970; 207:51-61. [PMID: 4323273 PMCID: PMC1348691 DOI: 10.1113/jphysiol.1970.sp009047] [Citation(s) in RCA: 50] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
1. Rat phrenic nerve-diaphragm preparations have been used to assess some effects of prolonged nerve stimulation on transmitter release.2. The amplitude of the end-plate potentials evoked by prolonged repetitive nerve stimulation fell gradually during stimulation. Most of this fall was due to a reduction in the number of transmitter quanta released by each nerve impulse; however there was also a small reduction in the muscle cell depolarization produced by each quantum of transmitter.3. Repetitive nerve stimulation also produced a small reduction in the amplitude of the miniature end-plate potentials. Recovery of amplitude occurred within about 7-8 min of ceasing stimulation.4. A much greater reduction in miniature end-plate potential amplitude accompanied prolonged nerve stimulation if hemicholinium was present in the bathing solution.5. Estimates of the ;readily available transmitter' (Elmqvist & Quastel, 1965b) were made at intervals following prolonged nerve stimulation. Readily available transmitter was reduced, and recovered over approximately 15 min.6. The relationship of these changes to the changes in nerve terminal synaptic vesicle numbers and volumes induced by similar prolonged nerve stimulation (Jones & Kwanbunbumpen, 1970) is discussed.
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An examination of the effects of osmotic pressure changes upon transmitter release from mammalian motor nerve terminals. J Physiol 1968; 197:639-57. [PMID: 4299014 PMCID: PMC1351753 DOI: 10.1113/jphysiol.1968.sp008579] [Citation(s) in RCA: 93] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
1. When the frequency of miniature end-plate potentials (m.e.p.p.s) was measured at neuromuscular junctions in rat diaphragm nerve preparations in vitro bathed in solutions having osmolarities between 200 and 700 m-osmoles/l. it was found that m.e.p.p. frequency was transiently increased by exposure to osmotic gradients exceeding 75 m-osmoles/l., and then declined, within 1 hr, to a steady level slightly higher than the control level of frequency. Smaller osmotic gradients caused a maintained increase in m.e.p.p. frequency. E.p.p. quantal content was initially increased and later profoundly decreased upon exposure of preparations to solutions with an osmotic pressure of 500 or 600 m-osmoles/l. but was unaffected by less hypertonic solutions.2. Variation of the Ca or Mg content of the bathing solutions did not alter these effects of osmotic pressure on the early transient increase in m.e.p.p. frequency or e.p.p. quantal content but affected the late steady increase in m.e.p.p. frequency.3. The value of the transient increase in m.e.p.p. frequency was exponentially related to the osmotic gradient in the range 0-300 m-osmoles/l. with a Q(10) of 1.95 (range 11-34 degrees C). Greater osmotic gradients did not further increase m.e.p.p. frequency. Variation of the ionic strength of the bathing medium did not influence osmotic effects upon frequency.4. The discrepancy between the effects of osmotic gradients upon spontaneous and nerve-impulse induced transmitter release was explained by an occlusion of the osmotic effects by depolarization of nerve terminals. Time-course studies showed that in the presence of 20 mM-KCl the m.e.p.p. frequency increase in response to an increase in osmotic pressure was small and was followed by a reduction in frequency to below control levels while osmotic pressure changes had no immediate effect upon m.e.p.p. frequency in solutions containing 30 mM-KCl.5. It was concluded that increased osmotic gradients could release transmitter by a mechanism independent of Ca and of nerve terminal depolarization.6. It is suggested that the initial transient effects of changes of osmotic gradient upon transmitter release are related to flow of water through the nerve terminal membrane, while the later effects are related to nerve terminal volume changes.
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Abstract
1. The relationship between the quantal content of end-plate potentials (e.p.p.s) and the bathing [Ca] and [Mg] was determined at neuromuscular junctions in the rat diaphragm in vitro.2. E.p.p.s were recorded intracellularly from preparations exposed to solutions with [Ca] between 0.05 and 10 mM and [Mg] between 0.1 and 12.5 mM. The quantal content of e.p.p.s was increased by raising the [Ca] over this range and decreased by raising the [Mg]. There appeared to be competition of Mg with Ca at three sites in the nerve terminal membrane.3. A kinetic scheme based on competition of Ca and Mg at three sites could quantitatively explain the effects of Ca and Mg upon the quantal content of e.p.p.s and also the effects of these ions upon miniature end-plate potential frequency.
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On the mechanism by which calcium and magnesium affect the spontaneous release of transmitter from mammalian motor nerve terminals. J Physiol 1968; 194:355-80. [PMID: 4295698 PMCID: PMC1365798 DOI: 10.1113/jphysiol.1968.sp008413] [Citation(s) in RCA: 183] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
1. The frequency of miniature end-plate potentials (m.e.p.p.s) was recorded from neuromuscular junctions in rat diaphragm phrenic nerve preparations in vitro after preparations had soaked in solutions containing Ca in concentrations between 10(-10) and 10(-2)M and a similar range of [Mg].2. Ethylenediamine tetra-acetate (EDTA) and ethyleneglycol bis (beta-aminoethyl ether) tetra-acetate (EGTA) buffers were added to prepare solutions with [Ca] and [Mg] below 10(-4)M. A computer program was used to estimate the free [Ca(2+)] in these solutions, and it was shown that the effects of Ca could be attributed to the free [Ca(2+)] in the bathing solution.3. M.e.p.p.s could still be detected without difficulty after soaking preparations for 6-8 hr in solutions containing EDTA or EGTA buffers and no added Ca. The basal frequency was unchanged upon exhibition of Ca in concentrations up to 10(-5)M and/or Mg in concentrations up to 10(-3)M.4. Ca in concentrations of and above 10(-4)M accelerated m.e.p.p. frequency from the basal level. This effect reached a maximum in [Ca] of 10 mM and raising the [Ca] above this level did not further change frequency. These effects were explained by the combination of Ca molecules with a nerve terminal receptor site. It was postulated that this combination allosterically activated the spontaneous release mechanism.5. Mg could accelerate m.e.p.p. frequency in the absence of added Ca. The interactions of Ca and Mg upon m.e.p.p. frequency indicated that Ca and Mg competed for the same sites.6. Raising the [H(+)] of the bathing medium accelerated m.e.p.p. frequency. This effect was thought to be exerted partly by combination with the same receptor sites as Ca and Mg and partly by variation of the ionization of the CaCl(2) of the bathing solution.
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The relationship between the state of nerve-terminal polarization and liberation of acetylcholine. Ann N Y Acad Sci 1967; 144:459-70. [PMID: 4295405 DOI: 10.1111/j.1749-6632.1967.tb53787.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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