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A national cohort study of community belonging and its influence on premature mortality. J Epidemiol Community Health 2024; 78:205-211. [PMID: 38182409 PMCID: PMC10958258 DOI: 10.1136/jech-2023-220688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Accepted: 12/09/2023] [Indexed: 01/07/2024]
Abstract
BACKGROUND Community belonging, an important constituent of subjective well-being, is an important target for improving population health. Ageing involves transitioning across different social conditions thus, community belonging on health may vary across the life course. Using a nationally representative cohort, this study estimates the life stage-specific impact of community belonging on premature mortality. METHODS Six cycles of the Canadian Community Health Survey (2000-2012) were combined and linked to the Canadian Vital Statistics Database (2000-2017). Respondents were followed for up to 5 years. Multivariable-adjusted modified Poisson regression models were used to estimate the relative risk of premature mortality for three life stages: early adulthood (18-35 years), middle adulthood (36-55 years) and late adulthood (56-70 years). RESULTS The final analytical sample included 477 100 respondents. Most reported a 'somewhat strong' sense of belonging (45.9%). Compared with their 'somewhat strong' counterparts, young adults reporting a 'somewhat weak' sense of belonging exhibited an increased relative risk (RR) of 1.76 (95% CI 1.27 to 2.43) for premature mortality, whereas middle-aged adults reporting the same exhibited a decreased RR of 0.82 (95% CI 0.69, 0.98). Among older adults, groups reporting a 'very strong' (RR 1.10, 95% CI 1.01, 1.21) or a 'very weak' sense (RR 1.14, 95% CI 1.01, 1.28) of belonging exhibited higher RRs for premature mortality. CONCLUSION The results demonstrate how community belonging relates to premature mortality differs across age groups underscoring the importance of considering life stage-specific perspectives when researching and developing approaches to strengthen belonging.
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"Whatever journey you want to take, I'll support you through": a mixed methods evaluation of a peer worker program in the hospital emergency department. BMC Health Serv Res 2024; 24:147. [PMID: 38287378 PMCID: PMC10826204 DOI: 10.1186/s12913-023-10532-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Accepted: 12/27/2023] [Indexed: 01/31/2024] Open
Abstract
BACKGROUND People who are unhoused, use substances (drugs and/or alcohol), and who have mental health conditions experience barriers to care access and are frequently confronted with discrimination and stigma in health care settings. The role of Peer Workers in addressing these gaps in a hospital-based context is not well characterized. The aim of this evaluation was to 1) outline the role of Peer Workers in the care of a marginalized populations in the emergency department; 2) characterize the impact of Peer Workers on patient care, and 3) to describe how being employed as a Peer Worker impacts the Peer. METHODS Through a concurrent mixed methods evaluation, we explore the role of Peer Workers in the care of marginalized populations in the emergency department at two urban hospitals in Toronto, Ontario Canada. We describe the demographic characteristics of patients (n = 555) and the type of supports provided to patients collected through a survey between February and June 2022. Semi-structured, in-depth interviews were completed with Peer Workers (n = 7). Interviews were thematically analyzed using a deductive approach, complemented by an inductive approach to allow new themes to emerge from the data. RESULTS Support provided to patients primarily consisted of friendly conversations (91.4%), discharge planning (59.6%), tactics to help the patient navigate their emotions/mental wellbeing (57.8%) and sharing their lived experience (50.1%). In over one third (38.9%) of all patient interactions, Peer Workers shared new information about the patient with the health care team (e.g., obtaining patient identification). Five major themes emerged from our interviews with Peer Workers which include: (1) Establishing empathy and building trust between the patient and their care team through self-disclosure; (2) Facilitating a person-centered approach to patient care through trauma-informed listening and accessible language; (3) Support for patient preferences on harm reduction; (4) Peer worker role facilitating self-acceptance and self-defined recovery; and (5) Importance of supports and resources to help Peer Workers navigate the emotional intensity of the emergency department. CONCLUSIONS The findings add to the literature on Peer Worker programs and how such interventions are designed to best meet the needs of marginalized populations.
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Towards a community-driven definition of community wellbeing: A qualitative study of residents. PLoS One 2023; 18:e0294721. [PMID: 37988338 PMCID: PMC10662708 DOI: 10.1371/journal.pone.0294721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Accepted: 11/06/2023] [Indexed: 11/23/2023] Open
Abstract
BACKGROUND Understanding what promotes or hinders a community's capacity to serve the priorities of its residents is essential for the alignment of citizen needs and governance. Participatory approaches that engage community residents on the topic of community wellbeing are useful methods for defining outcomes that reflect a community's goals and priorities. Using qualitative focus group methods, the aim of this study was to outline bottom-up definitions of community wellbeing from a diverse pool of community residents in Ontario, Canada. METHODS Semi-structured, two-hour group interviews were conducted with adult (≥18 years) participants (N = 15) residing in four communities across Canada's largest province of Ontario. Participants were purposively selected from a pool of screening questionnaires to ensure diverse group compositions based on race, gender, age, and educational attainment. Interviews were thematically analysed using descriptive and interpretive methods to characterize resident conceptions of community wellbeing. RESULTS Focus group participants were between 18 and 75 years of age and most had lived in their local community for 5 or more years. Four major themes emerged: (1) a sense of community belonging is cultivated through shared spaces, routines, support, and identities; (2) a community constitutes the amenities and social contexts that enable residents to thrive; (3) effective regional decision-making must be community-informed; and (4) the wellbeing of a community relies on equal opportunities for engagement and participation. CONCLUSIONS Residents described their communities and their associated wellbeing as a combination of accessible amenities and opportunities to engage without marginalization. This study underscores the value of participatory approaches in community wellbeing research, where the viewpoint and life experience of residents is used to inform local decision-making and service delivery. Future research will capture more diverse perspectives towards community belonging, particularly from community newcomers, for the development of regionally appropriate indicators of community wellbeing.
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Can the Healthcare System Improve Food Security? A Need for Collaborative Community Partnerships. Healthc Q 2022; 25:26-33. [PMID: 36153681 DOI: 10.12927/hcq.2022.26892] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
Abstract
The COVID-19 pandemic has heightened the food insecurity crisis in Canada, and existing supports have been largely insufficient to meet the food needs of communities. In response to increasing reports of food insecurity among Toronto residents during the pandemic, the Food RX program was developed as a collaborative initiative between FoodShare Toronto - a local, community-based food justice organization - and the University Health Network, a large university-affiliated hospital network in downtown Toronto, ON. This commentary describes the Food RX program, highlights the lessons learned during its early implementation and offers a set of recommendations for building community partnerships moving forward.
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Aberrant AZIN2 and polyamine metabolism precipitates tau neuropathology. J Clin Invest 2021; 131:126299. [PMID: 33586680 DOI: 10.1172/jci126299] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Accepted: 12/16/2020] [Indexed: 01/14/2023] Open
Abstract
Tauopathies display a spectrum of phenotypes from cognitive to affective behavioral impairments; however, mechanisms promoting tau pathology and how tau elicits behavioral impairment remain unclear. We report a unique interaction between polyamine metabolism, behavioral impairment, and tau fate. Polyamines are ubiquitous aliphatic molecules that support neuronal function, axonal integrity, and cognitive processing. Transient increases in polyamine metabolism hallmark the cell's response to various insults, known as the polyamine stress response (PSR). Dysregulation of gene transcripts associated with polyamine metabolism in Alzheimer's disease (AD) brains were observed, and we found that ornithine decarboxylase antizyme inhibitor 2 (AZIN2) increased to the greatest extent. We showed that sustained AZIN2 overexpression elicited a maladaptive PSR in mice with underlying tauopathy (MAPT P301S; PS19). AZIN2 also increased acetylpolyamines, augmented tau deposition, and promoted cognitive and affective behavioral impairments. Higher-order polyamines displaced microtubule-associated tau to facilitate polymerization but also decreased tau seeding and oligomerization. Conversely, acetylpolyamines promoted tau seeding and oligomers. These data suggest that tauopathies launch an altered enzymatic signature that endorses a feed-forward cycle of disease progression. Taken together, the tau-induced PSR affects behavior and disease continuance, but may also position the polyamine pathway as a potential entry point for plausible targets and treatments of tauopathy, including AD.
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Leveraging amino acid sensors as therapeutic targets for tauopathies and related dementias. Alzheimers Dement 2020. [DOI: 10.1002/alz.043859] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Impact of Surgeon's Experience on Vascular and Haemorrhagic Complications After Kidney Transplantation. J Vasc Surg 2019. [DOI: 10.1016/j.jvs.2018.12.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Large-Scale Production and Properties of a
Solvent-Detergent-Treated Factor IX Concentrate from
Human Plasma. Vox Sang 2017. [DOI: 10.1159/000461875] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Strategies to improve the outcome in locally advanced pancreatic cancer. MINERVA CHIR 2015; 70:97-106. [PMID: 25658301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Pancreatic cancer is associated with the worst prognosis of all gastrointestinal malignancies. The major reasons for the dismal outcome are late diagnosis due to unspecific symptoms and aggressive tumor biology. Although highly effective chemotherapeutic options have emerged within the last decade, radical resection offers the only chance of cure. Only 10-20% of patients are resectable at presentation, and 30-40% present with borderline resectable or locally advanced/unresectable tumors. Even if resectable, the 5-year-survival rate after complete resections remains unsatisfactory, with less than 25%. This article gives an overview on current therapy standards as well as on new approaches especially for locally advanced tumors and outlines the importance of ongoing research to improve prognosis.
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Gutes Ansprechen eines therapierefraktären metastasierten Malignen Melanoms auf palliative Immuntherapie mit Ipilimumab. AKTUELLE DERMATOLOGIE 2012. [DOI: 10.1055/s-0032-1308918] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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A qualitative and quantitative analysis of von Willebrand factor contained in a very high-purity plasma-derived FVIII concentrate. Vox Sang 2012; 103:35-41. [DOI: 10.1111/j.1423-0410.2011.01576.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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Kongressnachlese – Deutscher Pankreasclub 2010. Zentralbl Chir 2011. [DOI: 10.1055/s-0031-1271556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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[Neonates in the pediatric emergency room. An epidemiological study]. Arch Pediatr 2006; 13 Suppl 1:S69-72. [PMID: 17370400] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
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Human pre-alpha-inhibitor: isolation from a by-product of industrial scale plasma fractionation and structural analysis of its H3 heavy chain. JOURNAL OF CHROMATOGRAPHY. B, BIOMEDICAL SCIENCES AND APPLICATIONS 1997; 692:281-91. [PMID: 9188816 DOI: 10.1016/s0378-4347(97)00012-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Pre-alpha-inhibitor (P alpha I) is a serine proteinase inhibitor from human plasma. It comprises bikunin (BK) responsible for antiprotease activity, covalently linked to a heavy chain H3. Here we describe its isolation from a side fraction of an industrial preparation of plasma clotting factors. By using a highly specific polyclonal antiserum prepared from rabbit immunized with a H3P polypeptide obtained in a bacterial expression system, we were able to identify the fractions containing P alpha I. Then, taking advantage of the differential affinity of the members of the inter-alpha-inhibitor family (I alpha I) for heparin-Sepharose and blue-Sepharose, we isolated P alpha I. Its specific antitryptic activity was 580 IU/g, higher than that of I alpha I: 420 IU/g. Its M(r), determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis, with or without prior reduction, was 130,000. Its peptide chains were identified by N-terminal sequencing. The H3 heavy chain was isolated from P alpha I by alkaline dissociation and anion-exchange chromatography. Its electrophoretic mobility was compared to that of the HI and H2 heavy chains of I alpha I. In reducing conditions, it was quite similar to that of H2 (M(r) 85,000) but clearly different from that of H1 (M[r] 78,000). Thus, the so-determined apparent M(r) of H3 was overestimated since its molecular mass determined by MALDI-TOF was 74,100. This result agrees with the proposed structure for H3. Indeed, by carbohydrate analysis and PNGase F digestion, we demonstrate that the two potential N-glycosylation sites present in the core-protein (theoretical mass: 69,454) are really occupied by two N-glycans, probably of biantennary type.
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Development of an enzyme-linked immunosorbent assay for human plasma inter-alpha-trypsin inhibitor (ITI) using specific antibodies against each of the H1 and H2 heavy chains. J Immunol Methods 1996; 190:61-70. [PMID: 8601712 DOI: 10.1016/0022-1759(95)00257-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Inter-alpha-trypsin inhibitor (ITI) is a serine-proteinase inhibitor of human plasma enzymes. ITI is composed of three polypeptide chains covalently linked: bikunin, responsible for the antiprotease activity and two heavy chains H1 and H2. Human plasma also contains other components immunologically related to ITI such as pre-alpha-trypsin inhibitor (paI), inter-alpha-like inhibitor (IalphaLI) and free bikunin. The ELISA procedure we propose exclusively measures native ITI within the range 12.5-200 microgram/l. The intra- and interassay coefficients of variation were less than 5.6% and 8.7%, respectively. When ITI was added to plasma samples, full recovery was obtained. EDTA-plasma from 30 healthy individuals revealed a mean level of 241.5 mg/l (range 145.5-506). The high specificity, sensitivity, reproducibility and accuracy of the present assay should facilitate the specific measurement of native ITI in blood and thus might represent a useful tool for further physiopathological studies.
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Abstract
Inter-alpha-trypsin inhibitor (ITI) is a serine protease inhibitor found in human plasma. Its antiprotease activity is due to bikunin which is effective in various types of experimental shock and pancreatitis. Therefore ITI, which releases bikunin by proteolytic cleavage, could be of therapeutic interest. A method for the large-scale isolation of ITI from human plasma is described. ITI was purified from the prothrombin complex concentrate (PCC) by diethylaminoethyl-Sepharose fast-flow chromatography followed by a chromatographic step on immobilized heparin designed to remove C4, factor X and protein C. With this procedure, which was performed under mild conditions, a homogeneous preparation of native ITI was obtained, as demonstrated by electrophoretic and chromatographic analyses. ITI maintained its biological activity, as exhibited by its specific antitryptic activity of 420 +/- 65 IU/g. In order to decrease or eliminate the risk of transmission of viral disease due to lipid-enveloped viruses, the process incorporated a solvent-detergent treatment. Animal studies on the final product revealed no adverse side-effects in terms of toxicity, thrombogenicity or hypotension. This preparation appears suitable for therapeutic evaluation in animal experimental models.
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Chondroitin sulphate covalently cross-links the three polypeptide chains of inter-alpha-trypsin inhibitor. EUROPEAN JOURNAL OF BIOCHEMISTRY 1994; 221:881-8. [PMID: 7513643 DOI: 10.1111/j.1432-1033.1994.tb18803.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Inter-alpha-trypsin inhibitor (ITI) is a tight complex of three different proteins: bikunin and two heavy chains H1 and H2. In order to demonstrate that the three chains are covalently linked by a chondroitin sulphate chain as previously proposed [Enghild, J. J., Salvesen, G., Hefta, S. A., Thogersen, I. B., Rutherford, S. and Pizzo, S. V. (1991) J. Biol. Chem. 266, 747-751], ITI was extensively digested with thermolysin and the glycosaminoglycan-containing fragment was isolated from the digest by ion-exchange chromatography. Its peptide structural determination and mass spectrometry analysis both provide evidence that the different peptide chains constituting ITI are associated by the new cross-link described as the protein-glycosaminoglycan-protein cross-link.
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Human leucocyte elastase (HLE) preferentially cleaves the heavy chain H2 of inter-alpha-trypsin inhibitor (ITI). BIOLOGICAL CHEMISTRY HOPPE-SEYLER 1993; 374:895-901. [PMID: 7505589 DOI: 10.1515/bchm3.1993.374.7-12.895] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Inter-alpha-trypsin inhibitor (ITI) is a complex protein containing two heavy polypeptide chains (H1 and H2) and a light chain, which in the free state is known as bikunin. In vitro cleavage of ITI with different proteases releases bikunin, but does not abolish the antitryptic activity. To study the mechanism of bikunin release, ITI was incubated with human leucocyte elastase (HLE). The resulting ITI fragments were characterized by (i) their electrophoretic and chromatographic behavior. (ii) their immunological reactivity towards antibodies specific for each of the heavy chains H1 and H2, and (iii) their N-terminal sequences. Our results demonstrate that the H2 heavy chain of ITI is particularly sensitive to HLE, and that early cleavage products (M(r)-values 120-150,000) consist of H1 linked to bikunin. A scheme is proposed for the mechanism for ITI degradation.
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Interlaboratory evaluation of methods for the assay of Protein C in purified concentrates. JOURNAL OF THE INTERNATIONAL FEDERATION OF CLINICAL CHEMISTRY 1993; 5:106-11. [PMID: 10146222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
Determination of the quantity and activity of the Protein C molecule is of the utmost importance in highly purified concentrates prepared for replacement therapy. A multicenter study was undertaken to evaluate the comparability and accuracy of Protein C assays from commercial sources. Significant between-assay and interlaboratory differences were found for both functional and immunological assays. The interlaboratory variability is explained in part by the use of different control plasmas. The results also indicate the importance of the diluent used. This study emphasizes the need for standardized methods for determining the characteristics of Protein C concentrates.
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Properties of a highly purified human plasma factor IX:c therapeutic concentrate prepared by conventional chromatography. Vox Sang 1989; 57:225-32. [PMID: 2617959 DOI: 10.1111/j.1423-0410.1989.tb00832.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
We have characterized a highly purified (HP) factor IX concentrate intended for therapy of hemophilia B. The product has been prepared from pooled human plasma using a large-scale procedure combining three conventional chromatographic steps based on DEAE ion exchange and affinity on immobilized heparin. The specific activity of the product was 119 +/- 10 IU factor IX:c/mg protein (n = 15), corresponding to a purification factor of about 9,000. The concentrate was free of the vitamin K-dependent clotting factors II, VII and X and of proteins C and S. Most of the contaminants found in factor IX complex concentrate (PCC) were absent in this new product. High-molecular-weight kininogen, factors VIII, XI, XII or prekallikrein were not detected. There were no activated factors, such as factors IXa, and Xa, no thrombin and no phospholipids. Only two contaminants could be detected: C4 and inter-alpha-trypsin inhibitor (about 0.8 and 1.2 mg/1,000 IU factor IX:c, respectively). The purity of the product, as compared to PCC, was confirmed by sodium dodecylsulfate polyacrylamide gel electrophoresis, cellulose acetate electrophoresis, Grabar-Williams immunoelectrophoresis, and bidimensional immunoelectrophoresis. Thrombogenicity tests in rabbits revealed that the HP factor IX tested had a lower thrombogenic power than the PCC tested. The concentrate has been subjected to a 0.3% tri(n-butyl) phosphate-1% Tween 80 treatment for 6h at 25 degrees C during its production to reduce or eliminate the risk of transmission of plasma-borne lipid-enveloped viruses. These conditions inactivated more than 3.8 log10 of vesicular stomatitis virus and more than 4.3 log10 of sindbis virus within 1 and 2 h of treatment, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
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Properties of a Highly Purified Human Plasma Factor IX:c
Therapeutic Concentrate Prepared by Conventional Chromatography. Vox Sang 1989. [DOI: 10.1159/000461052] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Abstract
A human solvent-detergent (SD)-treated factor IX concentrate has been produced from cryoprecipitate-poor plasma using DEAE-Sepharose CL-6B and heparin-Sepharose CL-6B chromatography. The DEAE eluate was incubated with an SD mixture [0.3% tri(n-butyl) phosphate-1% Tween 80, 6-h at 24 degrees C] which was found to inactivate, in less than 1 h, more than 3.8 log10 of vesicular stomatitis virus and more than 4.8 log10 of Sindbis virus; the SD was removed by a subsequent heparin adsorption step. The specific activity of the concentrate was 10.9 +/- 1.3 IU factor IX: c/mg protein (n = 15). The factor IX coagulant to antigen ratio was 0.7 +/- 0.1. The concentrate was essentially free of factors II, VII and X, and protein C. The usual major contaminants of prothrombin complex concentrate (PCC) were absent: the concentrate contained about 94% alpha-1 proteins, and only 4 major proteins were resolved by SDS-PAGE (respective apparent molecular weight: 130, 86, 76 and 69 kilodaltons), and by crossed immunoelectrophoresis against an anti-PCC serum. The nonactivated partial thromboplastin time was equivalent to that of PCC; the product was devoid of factor IXa, of other activated procoagulant factors and of coagulant-active phospholipids (removed with SD in the heparin breakthrough fraction). Animal studies using the Wessler test and acute-toxicity test in rabbits revealed no adverse side effects. SD treatment could thus be used to inactivate viruses in factor IX concentrate and improve the safety of replacement therapy in hemophilia B.
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Reconstitution of the ubiquinol: cytochrome c reductase from a bc1 subcomplex and the 'Rieske' iron-sulfur protein isolated by a new method. EUROPEAN JOURNAL OF BIOCHEMISTRY 1983; 132:395-407. [PMID: 6301832 DOI: 10.1111/j.1432-1033.1983.tb07376.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
1. A method for preparing the 'Rieske' iron-sulfur protein and the bc1 subcomplex of complex III was developed. The new method is advantageous over the published ones in that: (a) the final yield and amount exceeds by far those obtained when employing the hitherto published methods; (b) the iron-sulfur protein as well as the bc1 subcomplex are obtained by one and the same preparation procedure from a common source; and (c) the preparation method is easier than the published ones. 2. The iron-sulfur protein obtained represents the first reconstitutively active preparation present in a monodisperse state. 3. The reconstitution of the ubiquinol:cytochrome c reductase from the two components is a reversible dissociation process. Full activity of ubiquinol:cytochrome c reductase is reached after saturation of the binding site of the bc1 subcomplex for iron-sulfur protein. 4. Full reduction of the constituent cytochrome c1 of the bc1 subcomplex can already be obtained with substoichiometric amounts of iron-sulfur protein, however. 5. The question might be raised whether the observed dissociation equilibrium represents merely a phenomenon occurring specifically with the proteins isolated in Triton X-100 and investigated in a Triton-containing buffer, or whether dissociation of the iron-sulfur protein also takes place in the mitochondrial membrane in the course of the electron-transfer reaction sequence.
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