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Self-reported beta-lactam allergy in government and private hospitals in Cape Town, South Africa. S Afr Med J 2023; 113:69-74. [PMID: 36757070 DOI: 10.7196/samj.2023.v113i2.16760] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Indexed: 02/10/2023] Open
Abstract
BACKGROUND Up to a quarter of inpatients in high-income countries (HICs) self-report beta-lactam allergy (BLA), which if incorrect,increases the use of alternative antibiotics, worsening individual health outcomes and driving bacterial resistance. In HICs, up to 95% ofself-reported BLAs are incorrect. The epidemiology of BLA in low- and middle-income African countries is unknown. OBJECTIVES To describe the epidemiology and de-labelling outcomes of self-reported BLA in hospitalised South African (SA) patients. METHODS Point-prevalence surveys were conducted at seven hospitals (adult, paediatric, government and privately funded, district andtertiary level) in Cape Town, SA, between April 2019 and June 2021. Ward prescription records and in-person interviews were conductedto identify and risk-stratify BLA patients using the validated PEN-FAST tool. De-labelling was attempted at the tertiary allergy clinic atGroote Schuur Hospital. RESULTS A total of 1 486 hospital inpatients were surveyed (1 166 adults and 320 children). Only 48 patients (3.2%) self-reported a BLA,with a higher rate in private than in government-funded hospitals (6.3% v. 2.8%; p=0.014). Using the PEN-FAST tool, only 10.4% (n=5/48)of self-reported BLA patients were classified as high risk for true penicillin hypersensitivity. Antibiotics were prescribed to 70.8% (n=34/48)of self-reported BLA patients, with 64.7% (n=22/34) receiving a beta-lactam. Despite three attempts to contact patients for de-labelling atthe allergy clinic, only 3/36 underwent in vivo testing, with no positive results, and 1 patient proceeded to a negative oral challenge. CONCLUSION Unlike HICs, self-reported BLA is low among inpatients in SA. The majority of those who self-reported BLA were low risk fortype 1 hypersensitivity, but outpatient de-labelling efforts were largely unsuccessful.
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Prevalence and Perceived Usefulness of Assistive Technology in Mind at Home Dementia Cohort. Innov Aging 2020. [PMCID: PMC7740999 DOI: 10.1093/geroni/igaa057.632] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
Dementia is generally characterized by both an increasing dependence in activities of daily living over the course of the illness, and a decreasing ability to self-manage everyday tasks. This places persons at risk for a number of undesirable outcomes including increased risk for injury in the home, increased risk for medical and behavioral complications, risk of premature institutionalization, and excessive burden on family caregivers (CG).3,4 Assistive Technology Devices (AT-Devices) could represent an efficient resource for supporting daily tasks while reducing both CG care burden and adverse risk to the person with dementia (PWD).3,4 In the context of a larger dementia care intervention clinical trial (The MIND at Home program) that involved persons living with dementia at home and their family caregivers, we conducted a supplemental baseline survey on 59 participants and their CGs to better understand the current prevalence of AT-Device use and which devices would be perceived as “most helpful”. Our analysis showed that 51% of our study population used at least 1 of our listed AT-Devices. The most common AT-Device used at baseline were door guards (29%), tablets/smartphones (20%), and constant temperature shower nozzles (13%). Our survey demonstrated devices perceived as most useful included: shower nozzles, GPS locating devices, door guards, and Bluetooth tracking stickers. Individuals who endorsed African-American/Other race were significantly more likely to use at least one AT-Device than those who identified as Caucasian (OR: 4.80; 95% CI: 1.50-17.58). This significance was lost during adjustment for other demographic variables (sex, age, cohabitation status, and dementia severity).
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Telehealth Use in a Home-Based Dementia Care-Coordination Program. Innov Aging 2020. [PMCID: PMC7740289 DOI: 10.1093/geroni/igaa057.633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
In the coming decades, greater numbers of people will either have Alzheimer’s Disease or a related dementia or will take care of a family member with dementia. The dementia syndromes are associated with increased risk of medical, social, and behavioral complications in both the person with dementia (PWD) and the caregiver (CG), many of which are preventable. These complications, and the dementia itself, can impede access to care and ultimately hasten residential care placement, which can be both undesirable and costly. A nearly universal unmet need in PWD/CG dyads is dementia-specific education. Therefore, it is vital we find ways to support and provide education to CG/PWD dyads to manage dementia in the community and home setting. MIND at Home is a dementia-care model developed and tested at Johns Hopkins University School of Medicine to minimize dementia complications and delay institutionalization by training non-clinical Memory Care Coordinators (MCCs) working under clinical supervision to support and guide PWD/CG dyads in the community. MCCs collaborate with CGs and PWDs in the community using an individualized care plan structured around the dyads’ specific dementia-related needs. This presentation will describe how the MIND at Home team used handheld tablets to connect MCCs to clinicians from participants’ homes, and will report on challenges encountered, strategies to address them, and participant and caregiver satisfaction with the telehealth experience.
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Exploring the Experiences of Persons Living With Dementia and Their Care Partners in a Memory Café-Style Program. Innov Aging 2020. [PMCID: PMC7742065 DOI: 10.1093/geroni/igaa057.874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
Community-based supportive care interventions are needed to address unmet needs and maximize quality of life for persons living with dementias and their care partners (care dyad). Memory cafés and similar programs serve as a potentially important vehicle to reduce dementia stigmatization, improve inclusiveness, promote well-being, socialization and meaningful activity engagement, and disseminate dementia-related education and knowledge. Despite gaining popularity, little is known about how these programs impact participants or how they work best. The Club Memory® program in Washington, D.C. is an enhanced memory café-style program that delivers a normalizing environment, decreased negative stigma and a chance to experience a catalyst for change despite disease progression. Using qualitative methods, we investigated the perceived impact, benefits, and weaknesses of Club Memory from multi-stakeholder perspective, to explore how this program might be improved and standardized for broader implementation. We conducted two focus groups, one of care partners and one of persons living with dementia (N=12). Upon analyzing transcriptions, five common themes emerged among the focus groups: Atmosphere, Sense of Community, Skill-Building, Tools and Strength in Staff. Integrating perspectives from the care dyad revealed congruent thoughts on program perception, benefits and strengths, and opportunities for improvement. Club Memory® appears to be a valuable model that creates a stigma-free supportive environment, educates and engages the care dyad to foster understanding, confidence, curiosity and empowerment. Our findings contribute to a deeper understanding of the impact community-based strategies can positively impact the care dyad’s life.
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Small molecule of adiponectin receptor agonist-AdipoRon-for Alzheimer disease: abridged secondary publication. Hong Kong Med J 2020; 26 Suppl 7:29-32. [PMID: 33229616] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023] Open
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Adiponectin gene therapy for Alzheimer disease in a mouse model: abridged secondary publication. Hong Kong Med J 2020; 26 Suppl 8:27-33. [PMID: 33504675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023] Open
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Surgical management of a retroperitoneal pelvic desmoid tumour involving the sacrifice of external iliac vein and internal iliac vessels. Gynecol Oncol Rep 2017; 20:87-89. [PMID: 28386580 PMCID: PMC5374851 DOI: 10.1016/j.gore.2017.03.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 03/02/2017] [Accepted: 03/11/2017] [Indexed: 11/25/2022] Open
Abstract
Retroperitoneal pelvic desmoid tumours are rare with limited publications. A rare case of a retroperitoneal pelvic desmoid tumour is discussed. Excision was challenging requiring the sacrifice of some of the iliac vessels. No other case reports document a surgical excision requiring this. To date our patient suffers minimal morbidity and has had no recurrences.
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Caring for Dying Patients in the Nursing Home: Voices From Frontline Nursing Home Staff. J Pain Symptom Manage 2017; 53:198-207. [PMID: 27815169 PMCID: PMC5463275 DOI: 10.1016/j.jpainsymman.2016.08.022] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Revised: 08/24/2016] [Accepted: 08/26/2016] [Indexed: 12/18/2022]
Abstract
CONTEXT Nursing homes are an important site for end-of-life care, yet little is known about the perspectives of the frontline staff who provide a majority of this care. OBJECTIVE To describe, from the staff perspective, positive/negative experiences related to caring for dying residents. METHODS Qualitative analysis using survey data from staff working in 52 Indiana nursing homes. RESULTS A total of 707 frontline staff who provide nursing, nurse aide, and social work services responded to open-ended prompts. Study data included responses to open-ended prompts asking participants to describe one positive experience and one negative experience caring for a dying patient. A thematic content analysis was conducted using the constant-comparative method. Respondents were largely female (93%), white (78%), 31-50 years (42%), and 53% had >5 years of nursing home work experience. Experiences were described from three perspectives: 1) first-hand experiences, 2) observed experiences of dying patients, and 3) observed experiences of family members. Selected themes for positive experiences include the following: creating close bonds; good patient care; involvement of hospice; being prepared; and good communication. Selected themes for negative experiences consisted of the following: challenging aspects of care; unacknowledged death; feeling helpless; uncertainty; absent family; painful emotions; and family discord. CONCLUSION Findings reveal the richness and many complexities of providing end-of-life care in nursing homes and have implications for improving staff knowledge, coordination of care with hospice, and social support for patients.
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Patient Reluctance to Discuss Pain: Understanding Stoicism, Stigma, and Other Contributing Factors. JOURNAL OF SOCIAL WORK IN END-OF-LIFE & PALLIATIVE CARE 2017; 13:27-43. [PMID: 28271970 DOI: 10.1080/15524256.2017.1282917] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Some patients are hesitant to disclose when they are experiencing pain. However, the reasons for this, such as stoicism and concern about being a bother to others, are poorly understood. If patient pain goes unrecognized during clinical encounters, patients may also be at greater risk for pain-related crises, use of hospice/palliative care on-call services, and in-patient transfers. This is an evidence-informed development of a practice-oriented conceptual model to understand and address patient reluctance to admit pain. We used a review of the available evidence to better understand the various factors that contribute to an unwillingness to disclose one's pain, create a conceptual model, and identify relevant assessment measures that may be useful to practitioners. Our review identified six primary attitudes and beliefs that contribute to patient reluctance to openly admit pain: (a) stigma; (b) stoicism; (c) cautiousness; (d) fatalism; (e) bother; and (f) denial. Four assessment measures that address elements of barriers to pain-related communication and four measures of nonverbal signs of pain were also identified and reviewed. Based on the model, social workers and other palliative care providers should consistently and vigilantly inquire about how comfortable patients are about discussing their own pain. Implications for practice and research are presented.
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Abstract
Hospital social workers are often the fulcrum of communication between physicians, patients, and families especially when patients are facing life-threatening illness. This study aims to understand the impact of a brief training for hospital social workers. The training is designed to improve communication skills and self-efficacy, as well as lessen fears of death and dying. Repeated-measures tests were used to assess outcomes across three time points. Twenty-nine university-based hospital social workers participated. Results trended in the desired directions. Communication self-efficacy improved immediately following the training, and this was sustained 1 month following training completion. Although participants were relatively experienced, improvement was still demonstrated and maintained suggesting brief communication training is promising for hospital social workers across the career.
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The Maverick ideas of red Toryism could give Cameron a potent edge. Chest 2009. [DOI: 10.5840/chesterton2009353/4100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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The quality of operative notes at a general surgery unit. S Afr Med J 2008; 98:726-728. [PMID: 19113057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023] Open
Abstract
AIM With the increasingly litigious nature of medical practice, accurate documentation is critical. This is particularly true for operative procedures, and medical councils have identified this and published guidelines to aid surgeons. However, these remain a frequently cited weakness in their defence in medico-legal cases. This study assessed the accuracy of operative notes in a general surgery unit in order to improve our practice. METHOD An audit of 100 consecutive operative notes was performed, and notes were assessed using the Royal College of Surgeons guidelines. The quality of note-taking of trainees was compared with that of consultant surgeons. A series of operation note pro formas was designed in response to the findings. RESULTS Of the notes, 66% were completed by trainees. The vast majority of notes had no diagram to demonstrate the surgical findings or illustrate the actions. Specialist surgeons were more likely to describe the actions accurately, but less likely to describe wound closure methods or dressings used. They were also less likely to complete adequate postoperative orders. CONCLUSIONS This study identifies key areas of weakness in our operative note-keeping. Pro formas should be introduced and made available for commonly performed procedures, and diagrams should be used wherever possible.
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Audit of appendicectomies at Frere Hospital, Eastern Cape. S AFR J SURG 2008; 46:74-77. [PMID: 18807302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
OBJECTIVE We sought to evaluate the surgical service in the central part of the Eastern Cape Province by reviewing the practice of appendicectomy at Frere Hospital. Specifically, it was our aim to compare the service to those patients who reside in and outside the East London metropolitan area and the outcomes of patients according to their operative finding. PATIENTS AND METHODS A retrospective study was performed on the medical records of all patients who underwent appendicectomy in a 26-month period. This entailed a thorough review of demographic factors, mode of presentation, operation factors and findings, and the postoperative course. RESULTS . In the study period, 436 appendicectomies were performed, of which 81% were performed after hours, with a consultant surgeon present in only 6% of cases. Of the group, 51% had a perforated appendix at surgery, and 12% a normal appendix. There was a significantly increased risk of perforation at the extremes of age and in patients from outside East London (63% v. 35% in East London). Those with perforated appendices stayed an average of 7.3 days in hospital, compared with 5 days for those with earlier appendicitis. Of the perforated group, 21% developed a complication, with 86% of all complications occurring in this group. The hospital stays were longer in those perforated appendices that were drained (10.7 days v. 6.1 days), and the rate of complications higher in this subgroup. Four patients died (1%)--all in the perforated group. DISCUSSION The perforation rate in our setting is significantly higher than other published results. Patients with perforated appendices have longer hospital stays and are more likely to develop significant complications, including re-operation. Patients from outside East London, males and those at the extremes of age are more likely to have perforated appendices. This study lends little support to the advocates of drains, and recommends the use of non-absorbable sutures for skin closure. The majority of procedures are performed after hours by medical officers and registrars, but there is no evidence to suggest that this practice be altered, particularly in light of the high perforation rate. The main factor identified as contributing to the huge discrepancy between perforation rates (and hence morbidity) is delay in presentation to the operating surgeon for the region. Patient factors may contribute, but service factors are regarded as significant, including poor access to clinics and hospitals, transport and ambulance services, and the expertise of the referring medical staff. The need to improve the quality of patient care in the under-serviced rural areas of the Eastern Cape is highlighted.
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A Preliminary Note on Tetramitus, a Stage in the Life Cycle of a Coprozoic Amoeba. Proc Natl Acad Sci U S A 2006; 8:294-300. [PMID: 16586900 PMCID: PMC1085151 DOI: 10.1073/pnas.8.10.294] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Abstract
BACKGROUND A 5-year experience with the modified sandwich-vacuum pack technique, using an opened 3-litre urological irrigation bag and continuous high-pressure suction, for temporary abdominal wall closure is presented. METHODS The records of all patients who underwent temporary abdominal wall closure using this method from January 1996 to December 2000 were examined. RESULTS The modified sandwich-vacuum pack was used 139 times in 55 patients. Forty patients sustained penetrating trauma while 15 patients sustained blunt trauma. The mean Injury Severity Score was 19 (range 9-34). Intra-abdominal sepsis (51 per cent) was the commonest indication, followed by visceral oedema (18 per cent), abdominal compartment syndrome (16 per cent), intra-abdominal packing (11 per cent) and abdominal wall defects (4 per cent). The overall mortality rate was 45 per cent. Three patients (5 per cent) developed enterocutaneous fistula. Of the 30 survivors, 16 patients underwent primary fascial closure. CONCLUSION The modified sandwich-vacuum pack technique of temporary abdominal wall closure is easy and rapid, cost effective and provides an effective means of containing abdominal wall contents.
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Abstract
Approximately one-third of patients with porphyria cutanea tarda (PCT), the most common porphyria in humans, inherit a single mutant allele of the uroporphyrinogen decarboxylase (URO-D) gene. PCT associated with URO-D mutations is designated familial PCT. The phenotype is characterized by a photosensitive dermatosis with hepatic accumulation and urinary excretion of uroporphyrin and hepta-carboxylic porphyrins. Most heterozygotes for URO-D mutations do not express a porphyric phenotype unless hepatic siderosis is present. Hemochromatosis gene (HFE) mutations are frequently found when the phenotype is expressed. We used homologous recombination to disrupt one allele of murine URO-D. URO-D(+/-) mice had half-wild type (wt) URO-D protein and enzymatic activity in all tissues but did not accumulate hepatic porphyrins, indicating that half-normal URO-D activity is not rate limiting. When URO-D(+/-) mice were injected with iron-dextran and given drinking water containing delta-aminolevulinic acid for 21 days, hepatic porphyrins accumulated, and hepatic URO-D activity was reduced to 20% of wt. We bred mice homozygous for an HFE gene disruption (HFE(-/-)) to URO-D(+/-) mice, generating mice with the URO-D(+/-)/HFE(-/-) genotype. These animals developed a porphyric phenotype by 14 weeks of age without ALA supplementation, and URO-D activity was reduced to 14% of wt. These data indicate that iron overload alone is sufficient to reduce URO-D activity to rate-limiting levels in URO-D(+/-) mice. The URO-D(+/-) mouse serves as an excellent model of familial PCT and affords the opportunity to define the mechanism by which iron influences URO-D activity.
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Abstract
A procedure is described that directs the self-induced deletion of DNA sequences as they pass through the male germ line of mice. The testes-specific promoter from the angiotensin-converting enzyme gene was used to drive expression of the Cre-recombinase gene. Cre was linked to the selectable marker Neor, and the two genes flanked with loxP elements. This cassette was targeted to the Hoxa3 gene in mouse ES cells that were in turn used to generate chimeric mice. In these chimeras, somatic cells derived from the ES cells retained the cassette, but self-excision occurred in all ES-cell-derived sperm.
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Abstract
Diacylglycerol kinases (DGKs) terminate signalling from diacylglycerol by converting it to phosphatidic acid. Diacylglycerol regulates cell growth and differentiation, and its transient accumulation in the nucleus may be particularly important in this regulation. Here we show that a fraction of DGK-zeta is found in the nucleus, where it regulates the amount of nuclear diacylglycerol. Reducing nuclear diacylglycerol levels by conditional expression of DGK-zeta attenuates cell growth. The nuclear-localization signal of DGK-zeta is located in a region that is homologous to the phosphorylation-site domain of the MARCKS protein. This is, to our knowledge, the first evidence that this domain, which is a major target for protein kinase C, can localize a protein to the nucleus. Two isoforms of protein kinase C, but not others, regulate the localization of DGK-zeta. Our results define a cycle in which diacylglycerol activates protein kinase C, which then regulates the metabolism of diacylglycerol by alternating the intracellular location of DGK-zeta. This may be a general mechanism to control mitogenic signals that depend on nuclear diacylglycerol.
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Alpha toxin from Clostridium perfringens induces proinflammatory changes in endothelial cells. J Clin Invest 1997; 100:565-74. [PMID: 9239403 PMCID: PMC508223 DOI: 10.1172/jci119566] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Alpha toxin from Clostridium perfringens type A, a phospholipase C, has been implicated in many of the localized and systemic features of gas gangrene. We demonstrated that human endothelial cells synthesize two vasoactive lipids, platelet-activating factor (PAF) and prostacyclin, in response to alpha toxin treatment. The stimulated synthesis of PAF required the enzymatic activity of the toxin and subsequent protein kinase C activation. Alpha toxin-treated endothelial cells accumulated the products of the phospholipase C reaction, diacylglycerol and ceramide, and exhibited a decrease in the enzymatic precursors phosphatidylcholine and sphingomyelin. Furthermore, the temporal accumulation of PAF depended on the concentration of the toxin in the overlying medium and was blocked in the presence of a neutralizing antibody. The cultured endothelial cells also exhibited enhanced neutrophil adhesion in response to alpha toxin which was mediated through the PAF receptor and P-selectin. P-selectin expression by endothelial cells and extravascular neutrophil accumulation were also observed in tissue sections from alpha toxin-injected Sprague-Dawley rats. These endothelial cell-mediated processes are important in maintaining vascular homeostasis and, when activated in a dysregulated manner by C. perfringens alpha toxin, may contribute to localized and systemic manifestations of gas gangrene including enhanced vascular permeability, localized neutrophil accumulation, and myocardial dysfunction.
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Alternative splicing of the human diacylglycerol kinase zeta gene in muscle. Proc Natl Acad Sci U S A 1997; 94:5519-24. [PMID: 9159104 PMCID: PMC20810 DOI: 10.1073/pnas.94.11.5519] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/1997] [Accepted: 03/24/1997] [Indexed: 02/04/2023] Open
Abstract
Diacylglycerol can function as a second messenger, and one mechanism for the attenuation of this signal is its conversion to phosphatidic acid, which is catalyzed by diacylglycerol kinase (DGK). We screened a cDNA library from human skeletal muscle and isolated two DGKzeta cDNAs that differed from the 3.5-kb clone originally identified in endothelial cells. One transcript, which was 3.4 kb long, was shown to be nonfunctional; it had a 77-bp deletion that included the translation initiation site. The other was 4.1 kb long with a unique 5' sequence of 853 bp. We also isolated a genomic clone of DGKzeta and determined its organization and location; it contains 32 exons, spans approximately 50 kb of genomic sequence, and maps to chromosome 11p11.2. The protein encoded by the 4.1-kb transcript contains two cysteine-rich regions, a catalytic domain, and ankyrin repeats like the endothelial form of DGKzeta, as well as a unique N-terminal domain. The coding sequence was shown to be derived from alternative splicing of the DGKzeta gene. In cells transfected with the 4.1-kb clone, we detected a 130-kDa protein with an antibody to DGKzeta and demonstrated that it was localized predominantly in the nucleus. We conclude that alternative splicing generates tissue-specific variants of DGKzeta that share some properties but may have unique ones as well.
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Molecular cloning and characterization of a novel human diacylglycerol kinase zeta. J Biol Chem 1996; 271:10230-6. [PMID: 8626588] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Diacylglycerol (DAG) occupies a central position in the synthesis of complex lipids and also has important signaling roles. For example, DAG is an allosteric regulator of protein kinase C, and the cellular levels of DAG may influence a variety of processes including growth and differentiation. We previously demonstrated that human endothelial cells derived from umbilical vein express growth-dependent changes in their basal levels of diacylglycerol and diacylglycerol kinase activity (Whatley, R. E., Stroud, E. D., Bunting, M., Zimmerman, G. A., McIntyre, T. M., and Prescott, S. M. (1993) J. Biol. Chem. 268, 16130-16138). To further explore the role of diacylglycerol metabolism in endothelial responses, we used a degenerate reverse transcription-polymerase chain reaction method to identify diacylglycerol kinase isozymes expressed by human endothelial cells. We report the isolation of a 3.5-kilobase cDNA encoding a novel diacylglycerol kinase (hDGKzeta) with a predicted molecular mass of 103.9 kDa. Human DGK zeta contains two zinc fingers, an ATP binding site, and four ankyrin repeats near the carboxyl terminus. A unique feature, as compared with other diacylglycerol kinases, is the presence of a sequence homologous to the MARCKS phosphorylation site domain. From Northern blot analysis of multiple tissues, we observed that hDGKzeta mRNA is expressed at highest levels in brain. COS-7 cells transfected with the hDGKzeta cDNA express 117-kDa and 114-kDa proteins that react specifically with an antibody to a peptide derived from a unique sequence in hDGK zeta. The transfected cells also express increased diacylglycerol kinase activity, which is not altered in the presence of R59949, an inhibitor of human platelet DGK activity. The hDGKzeta displays stereoselectivity for 1,2-diacylglycerol species in comparison to 1,3-diacylglycerol, but does not exhibit any specificity for molecular species of long chain diacylglycerols.
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Molecular cloning of a novel human diacylglycerol kinase highly selective for arachidonate-containing substrates. J Biol Chem 1996; 271:10237-41. [PMID: 8626589] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Diacylglycerol (DAG) is a second messenger that activates protein kinase C and also occupies a central role in phospholipid biosynthesis. Conversion of DAG to phosphatidic acid by DAG kinase regulates the amount of DAG and the route it takes. We used degenerate primers to amplify polymerase chain reaction products from cDNA derived from human endothelial cells. A product with a novel sequence was identified and used to clone a 2.6-kilobase cDNA from an endothelial cell library. When transfected with a truncated version of this cDNA, COS-7 cells had a marked increase in DAG kinase activity, which demonstrated clear selectivity for arachidonoyl-containing species of diacylglycerol. The open reading frame of this clone has 567 residues with a predicted protein of 64 kDa. This enzyme, which we designated DGK epsilon, has two distinctive zinc finger-like structures in its N-terminal region, but does not contain the E-F hand motifs found in several other mammalian DGKs. The catalytic domain of DGK epsilon, which is related to other DGKs, contains two ATP-binding motifs. Northern blotting demonstrated that DGK epsilon is expressed predominantly in testis. This unique diacylglycerol kinase may terminate signals transmitted through arachidonoyl-DAG or may contribute to the synthesis of phospholipids with defined fatty acid composition.
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Growth-dependent changes in arachidonic acid release from endothelial cells are mediated by protein kinase C and changes in diacylglycerol. J Biol Chem 1993; 268:16130-8. [PMID: 8344898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
When stimulated, endothelial cells release arachidonic acid from phospholipids and oxidize it to eicosanoids. The rate-limiting step in this pathway is the initial release step, catalyzed by phospholipase(s), a process that exhibits growth-dependent changes. We examined the role of protein kinase C (PKC) as a regulator of this process. Activators and inhibitors of protein kinase C, used at different growth states, demonstrated distinct differences in their effects on arachidonic acid release, consistent with a growth-dependent change in PKC activity (with greater activity in proliferating cells compared with quiescent cells). Although immunoreactive PKC was slightly greater in the proliferating cells, there was a more striking redistribution of PKC activity between cytosol and membrane. To identify the cause, we measured the diacylglycerol (DG) content and found that DG concentrations decreased as cells progressed from preconfluence to confluence. Further studies demonstrated increases in DG kinase and DG lipase in confluent compared with preconfluent cells, consistent with the alterations in DG content. These findings suggest that growth-dependent changes in DG lipase and DG kinase activities regulate basal DG levels and PKC activity. The consequent alteration in PKC activity regulates the growth-dependent changes in arachidonic acid release.
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Abstract
The recent determination of the site-specific DNA binding properties of several proteins related to the ets oncoprotein has allowed the definition of a novel DNA binding domain, designated the ETS domain. In Drosophila, an ETS domain is present in the early ecdysone-induced E74A protein, which binds DNA in a site-specific manner and interacts with many ecdysone-induced polytene chromosome puffs at the onset of metamorphosis. As a first step toward determining the function of ETS-domain proteins during Drosophila development, we have used PCR amplification with degenerate oligonucleotides to isolate five other ets-related genes. Two of these genes, D-ets-2 and D-elg, have been previously identified. The proteins encoded by these genes are highly related to one another and to the seven identified vertebrate ETS-domain proteins, within the approximately 85-amino-acid DNA binding domain. In situ hybridization to polytene chromosomes revealed that these ets-related genes are not clustered in the genome and that only E74 corresponds to an ecdysone-inducible puff locus. These five ets-related genes are distinguished further from E74 in that they are transcribed through most of development, suggesting that they do not perform a stage-specific function. They are, however, expressed in a variety of patterns in early embryos, suggesting roles in the development of specific cell types. D-ets-2 is expressed in a complex pattern that changes dynamically during early embryogenesis. D-ets-3 and D-ets-6 are expressed in the ventral nervous system. The expression of D-ets-3 is higher in the three thoracic segments and lower in the abdominal segments. The high levels of expression in the thoracic segments are dependent on the presence of the bithorax complex. D-ets-4 and D-elg are expressed at their highest levels in the pole cells, suggesting a role in the development of the germline. This study represents the first effort in any organism to systematically isolate members of the ets gene family. The identification of six independent ets-related genes demonstrates that the ETS-domain proteins constitute a new family of potential transcriptional regulators encoded by the Drosophila genome.
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