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De Groot LM, Shearer K, Sambani C, Kaonga E, Nyirenda R, Mbendera K, Golub JE, Hoffmann CJ, Mulder C. Health care providers acceptance of default prescribing of TB preventive treatment for people living with HIV in Malawi: a qualitative study. BMC Health Serv Res 2024; 24:15. [PMID: 38178173 PMCID: PMC10768226 DOI: 10.1186/s12913-023-10493-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Accepted: 12/18/2023] [Indexed: 01/06/2024] Open
Abstract
BACKGROUND Tuberculosis (TB) preventive treatment (TPT) substantially reduces the risk of developing active TB for people living with HIV (PLHIV). We utilized a novel implementation strategy based on choice architecture (CAT) which makes TPT prescribing the default option. Through CAT, health care workers (HCWs) need to "opt-out" when choosing not to prescribe TPT to PLHIV. We assessed the prospective, concurrent, and retrospective acceptability of TPT prescribing among HCWs in Malawi who worked in clinics participating in a cluster randomized trial of the CAT intervention. METHODS 28 in-depth semi-structured interviews were conducted with HCWs from control (standard prescribing approach) and intervention (CAT approach) clinics. The CAT approach was facilitated in intervention clinics using a default prescribing module built into the point-of-care HIV Electronic Medical Record (EMR) system. An interview guide for the qualitative CAT assessment was developed based on the theoretical framework of acceptability and on the normalization process theory. Thematic analysis was used to code the data, using NVivo 12 software. RESULTS We identified eight themes belonging to the three chronological constructs of acceptability. HCWs expressed no tension for changing the standard approach to TPT prescribing (prospective acceptability); however, those exposed to CAT described several advantages, including that it served as a reminder to prescribe TPT and routinized TPT prescribing (concurrent acceptability). Some felt that CAT may reduce HCW´s autonomy and might lead to inappropriate TPT prescribing (retrospective acceptability). CONCLUSIONS The default prescribing module for TPT has now been incorporated into the point-of-care EMR system nationally in Malawi. This seems to fit the acceptability of the HCWs. Moving forward, it is important to train HCWs on how the EMR can be leveraged to determine who is eligible for TPT and who is not, while acknowledging the autonomy of HCWs.
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Affiliation(s)
- L M De Groot
- TB Elimination and Health System Innovations - KNCV Tuberculosis Foundation, The Hague, The Netherlands
| | - K Shearer
- Center for Tuberculosis Research, John Hopkins University, Baltimore, MD, USA
- Division of Infectious Diseases, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
| | - C Sambani
- Department of Research, Ministry of Health, Lilongwe, Malawi
| | - E Kaonga
- KNCV Tuberculosis Foundation, Lilongwe, Malawi
| | - R Nyirenda
- Department of HIV and AIDS, Ministry of Health, Lilongwe, Malawi
| | - K Mbendera
- National Tuberculosis and Leprosy Elimination Program, Ministry of Health, Lilongwe, Malawi
| | - J E Golub
- Center for Tuberculosis Research, John Hopkins University, Baltimore, MD, USA
- Division of Infectious Diseases, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - C J Hoffmann
- Center for Tuberculosis Research, John Hopkins University, Baltimore, MD, USA
- Division of Infectious Diseases, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
- Department of Health, Behavior and Society, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - C Mulder
- TB Elimination and Health System Innovations - KNCV Tuberculosis Foundation, The Hague, The Netherlands.
- Amsterdam Institute for Global Health and Development, Amsterdam University Medical Centres, Amsterdam, The Netherlands.
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Chimoyi L, Smith H, Hausler H, Fielding K, Hoffmann CJ, Herce ME, Charalambous S. Delivery of TB preventive therapy to incarcerated people living with HIV in southern African correctional facilities. Public Health Action 2021; 11:171-173. [PMID: 34956843 DOI: 10.5588/pha.21.0056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2021] [Accepted: 11/06/2021] [Indexed: 11/10/2022] Open
Abstract
TB preventive treatment (TPT) is recommended for high-risk and hard-to-reach populations such as incarcerated people living with HIV (PLHIV). To assess implementation of TPT delivery in correctional settings, we conducted an exploratory analysis of data from a multisite cohort study in South Africa and Zambia. From 975 participants, 648 were screened for TB, and 409 initiated TPT mostly within a month after initiation of antiretroviral therapy (190/409, 46.5%). We observed a median gap of one month (IQR 0.6-4.7) in TPT delivery to incarcerated PLHIV. Future research should examine standardised quality improvement tools and new strategies such as short-course regimens to improve TPT initiation in this population.
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Affiliation(s)
- L Chimoyi
- The Aurum Institute, Parktown, Johannesburg, South Africa
| | - H Smith
- Centre for Infectious Disease Research in Zambia, Lusaka, Zambia.,School of Population Health, University of New South Wales, Sydney, NSW, Australia
| | - H Hausler
- TB HIV Care, Cape Town, South Africa
| | - K Fielding
- London School of Tropical Hygiene & Medicine, London, UK
| | - C J Hoffmann
- The Aurum Institute, Parktown, Johannesburg, South Africa.,Johns Hopkins University, Baltimore, MD, USA
| | - M E Herce
- Centre for Infectious Disease Research in Zambia, Lusaka, Zambia.,Institute for Global Health & Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, NC, USA
| | - S Charalambous
- The Aurum Institute, Parktown, Johannesburg, South Africa.,School of Public Health, University of the Witwatersrand, Johannesburg, South Africa
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Mabuto T, Holzman S, Kubeka G, Hoffmann CJ. Mobile HIV testing in South Africa: maximizing yield through data-guided site selection. Public Health Action 2021; 11:155-161. [PMID: 34567992 DOI: 10.5588/pha.21.0016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 06/30/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Mobile community HIV testing can effectively reach undiagnosed people living with HIV in southern Africa. Variable yield in HIV test positivity has been a challenge with high- and low-yield sites often being closely situated. We sought to test whether easy-to-identify, site-level characteristics were associated with HIV positivity yield in a routine mobile HIV testing program. METHODS We used routine testing program test data augmented with site-level characterization, either of the community or shopping site at which HIV testing was offered. Specifically, we described the local environment and interviewed key informants to gain additional information regarding the availability of HIV and other services in the locale. RESULTS We included 122 residential and 26 shopping sites with median HIV-positive test yields of 7.6% and 6.9%, respectively. The range for community sites was from 2 to 55% with high and low yields at geographically proximal sites. Factors related to lower income and marginalization, including informal housing and the absence of name-brand stores in shopping venues, were associated with higher HIV-positive testing yield. CONCLUSIONS Characterization of sites, particularly identifying factors related to marginalization, lack of services, and poverty, can aid in identifying sites with higher HIV-positive yield.
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Affiliation(s)
- T Mabuto
- Aurum Institute, Johannesburg, South Africa.,School of Public Health, University of the Witwatersrand, Johannesburg, South Africa
| | - S Holzman
- Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - G Kubeka
- Aurum Institute, Johannesburg, South Africa
| | - C J Hoffmann
- Aurum Institute, Johannesburg, South Africa.,Johns Hopkins University School of Medicine, Baltimore, MD, USA
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Rickman HM, Cohn S, Lala SG, Waja Z, Salazar-Austin N, Hoffmann J, Dooley KE, Hoffmann CJ, Chaisson RE, Martinson NA. Subclinical tuberculosis and adverse infant outcomes in pregnant women with HIV. Int J Tuberc Lung Dis 2021; 24:681-685. [PMID: 32718400 PMCID: PMC10111371 DOI: 10.5588/ijtld.19.0500] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND: Tuberculosis (TB) in pregnant women with HIV is associated with adverse maternal and infant outcomes. Previous studies have described a substantial prevalence of subclinical TB in this group, but little is known about the impact of subclinical TB on maternal and pediatric outcomes.METHODS: The Tshepiso Study recruited 235 HIV-infected pregnant women with TB (and matched HIV-positive, TB-negative pregnant controls), in Soweto, South Africa, from 2011 to 2014. During enrolment screening, some women initially recruited as controls were subsequently diagnosed with prevalent TB. We therefore assessed the prevalence of subclinical TB, associated participant characteristics and outcomes.RESULTS: Of 162 women initially recruited as TB-negative controls, seven (4.3%) were found to have TB on sputum culture. All seven had negative WHO symptom screens, and six (86%) were smear-negative. Of their seven infants, one was diagnosed with TB, and three (43%) experienced complications compared to zero infants with TB and 11% experiencing complications in the control group of TB-negative mothers (P = 0.045).CONCLUSION: We discovered an appreciable prevalence of subclinical TB in HIV-infected pregnant women in Soweto, which had not been detected by screening algorithms based solely on symptoms. Infants of HIV-infected mothers with subclinical TB appear to have a higher risk of adverse outcomes than those of TB-negative mothers.
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Affiliation(s)
- H M Rickman
- The Center for TB Research, Johns Hopkins University School of Medicine, Baltimore, MD, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - S Cohn
- The Center for TB Research, Johns Hopkins University School of Medicine, Baltimore, MD
| | - S G Lala
- Department of Paediatrics and Child Health, Chris Hani Baragwanath Academic Hospital and University of the Witwatersrand, Johannesburg
| | - Z Waja
- Perinatal HIV Research Unit (PHRU), South African Medical Research Council Soweto, Matlosana Collaborating Centre for HIV/AIDS and TB, University of the Witwatersrand, Johannesburg South Africa
| | - N Salazar-Austin
- The Center for TB Research, Johns Hopkins University School of Medicine, Baltimore, MD
| | - J Hoffmann
- The Center for TB Research, Johns Hopkins University School of Medicine, Baltimore, MD
| | - K E Dooley
- The Center for TB Research, Johns Hopkins University School of Medicine, Baltimore, MD
| | - C J Hoffmann
- The Center for TB Research, Johns Hopkins University School of Medicine, Baltimore, MD
| | - R E Chaisson
- The Center for TB Research, Johns Hopkins University School of Medicine, Baltimore, MD, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - N A Martinson
- The Center for TB Research, Johns Hopkins University School of Medicine, Baltimore, MD, Perinatal HIV Research Unit (PHRU), South African Medical Research Council Soweto, Matlosana Collaborating Centre for HIV/AIDS and TB, University of the Witwatersrand, Johannesburg South Africa
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Caturegli G, Materi J, Lombardo A, Milovanovic M, Yende N, Variava E, Golub JE, Martinson NA, Hoffmann CJ. Choice architecture-based prescribing tool for TB preventive therapy: a pilot study in South Africa. Public Health Action 2020; 10:118-123. [PMID: 33134126 DOI: 10.5588/pha.20.0020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2020] [Accepted: 06/22/2020] [Indexed: 11/10/2022] Open
Abstract
Background All people with HIV who screen negative for active tuberculosis (TB) should receive isoniazid preventive therapy (IPT). IPT implementation remains substantially below the 90% WHO target. This study sought to further understanding of IPT prescription by piloting a simplified prescribing approach. Setting Primary care clinics in Matlosana, South Africa. Design This was a mixed-methods implementation study. Methods Nine providers were recruited and underwent training on 2018 WHO guidelines. A simplified prescribing tool containing antiretroviral therapy (ART) and IPT prescriptions was introduced into the workflow for 2 weeks. Prescription data were collected from file review. Interviews were conducted with prescribers. Results During the study period, 41 patients were evaluated for ART initiation; 34 (83%) files used the simplified prescribing tool. Thirty-seven (90%) patients were eligible for same-day ART and IPT initiation, of whom 36 (97%) received IPT prescription. Qualitative interviews identified the following barriers to IPT prescription: cognitive burden, extensive documentation, limited management support, paucity of training, stock-outs, and patient-related factors. Provider acceptability of the tool was favorable, with unanimous recommendation to colleagues on the basis of streamlining documentation and reminding to prescribe. Conclusions This simplified prescribing device for IPT was feasible to implement. Streamlining documentation and reminding providers to prescribe can reduce work-flow barriers to IPT provision.
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Affiliation(s)
- G Caturegli
- Division of Infectious Disease, School of Medicine, Johns Hopkins University, Baltimore, Maryland, USA
| | - J Materi
- Division of Infectious Disease, School of Medicine, Johns Hopkins University, Baltimore, Maryland, USA
| | - A Lombardo
- Division of Infectious Disease, School of Medicine, Johns Hopkins University, Baltimore, Maryland, USA
| | - M Milovanovic
- Perinatal HIV Research Unit, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg South Africa
| | - N Yende
- Perinatal HIV Research Unit, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg South Africa
| | - E Variava
- Department of Medicine, Tshepong Hospital, Klerksdorp, South Africa
| | - J E Golub
- Division of Infectious Disease, School of Medicine, Johns Hopkins University, Baltimore, Maryland, USA.,Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, USA
| | - N A Martinson
- Perinatal HIV Research Unit, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg South Africa
| | - C J Hoffmann
- Division of Infectious Disease, School of Medicine, Johns Hopkins University, Baltimore, Maryland, USA
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Kim HY, Zishiri V, Page-Shipp L, Makgopa S, Churchyard GJ, Dowdy D, Charalambous S, Hoffmann CJ. Symptom and digital chest X-ray TB screening in South African prisons: yield and cost-effectiveness. Int J Tuberc Lung Dis 2020; 24:295-302. [PMID: 32228759 DOI: 10.5588/ijtld.19.0214] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND: Correctional inmates are at a high risk of tuberculosis (TB). The optimal approach to screening this population is unclear.METHODS: We retrospectively reviewed records from TB screening in 64 correctional facilities in South Africa between January 2015 and July 2016. Inmates received symptom screening (any of cough, fever, weight loss, or night sweats) combined with digital chest X-ray (CXR), when available. CXRs were assessed as 'abnormal' or with no abnormalities. Inmates with either a symptom or an 'abnormal' CXR were asked to provide a single spot sputum for Xpert® MTB/RIF testing. We estimated the incremental cost-effectiveness ratio (ICER) per additional TB case detected using CXR screening among asymptomatic inmates.RESULTS: Of 61 580 inmates, CXR screening was available for 41 852. Of these, 19 711 (47.1%) had TB symptoms. Among 22 141 inmates without symptoms, 1939/19 783 (9.8%) had an abnormal CXR, and 8 (1.2%) were Xpert-positive among those with Xpert tests done. Of 14 942 who received symptom screening only and had symptoms, 84% (12 616) had an Xpert result, and 105 (0.8%) were positive. The ICER for CXR screening was US$22 278.CONCLUSION: Having CXR in addition to symptom screening increased yield but added considerable cost. A major limitation of screening was the low specificity of the symptom screen.
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Affiliation(s)
- H-Y Kim
- Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA, KwaZulu-Natal Research Innovation and Sequencing Platform (KRISP), Durban
| | | | | | | | - G J Churchyard
- The Aurum Institute, Johannesburg, School of Public Health, University of Witwatersrand, Johannesburg, South Africa
| | - D Dowdy
- Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - S Charalambous
- The Aurum Institute, Johannesburg, School of Public Health, University of Witwatersrand, Johannesburg, South Africa
| | - C J Hoffmann
- The Aurum Institute, Johannesburg, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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7
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Fischbach W, Malfertheiner P, Lynen Jansen P, Bolten W, Bornschein J, Buderus S, Glocker E, Hoffmann CJ, Koletzko S, Labenz J, Mayerle J, Miehlke S, Mössner J, Peitz U, Prinz C, Selgrad M, Suerbaum S, Venerito M, Vieth M. [S2k-guideline Helicobacter pylori and gastroduodenal ulcer disease]. Z Gastroenterol 2016; 54:1. [PMID: 27168132 DOI: 10.1055/s-0035-1567086] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
In the line "bismuth-containing quadruple therapy" of Table 7 (p 342), in the column "dosage" incorrectly at the three antibiotics respectively 1-1-1-1. The correct is: 3-3-3-3.
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Zishiri V, Chihota V, McCarthy K, Charalambous S, Churchyard GJ, Hoffmann CJ. Pooling sputum from multiple individuals for Xpert® MTB/RIF testing: a strategy for screening high-risk populations. Int J Tuberc Lung Dis 2015; 19:87-90. [PMID: 25519796 DOI: 10.5588/ijtld.14.0372] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
SETTING Symptom-based screening for tuberculosis (TB) disease is limited by poor performance of symptom screening in several key populations. We tested the hypothesis that pooling sputum from multiple individuals for Xpert(®) MTB/RIF testing would reduce the number of tests required while retaining an acceptable sensitivity, thus allowing the use of Xpert for TB screening. METHODS We compared pooling ratios that would require the least number of assays using Xpert and determined that for a population with a TB prevalence of approximately 3%, a 1:5 pooling ratio is optimal. To evaluate sensitivity, we generated pools of one specimen with known Mycobacterium tuberculosis culture positivity (smear microscopy-positive or -negative) with four culture-negative specimens. RESULTS All 20 of the pools generated from a smear- and culture-positive sputum sample were positive using Xpert. Of the 22 pools with a smear-negative, culture-positive sample, we included 17 in the analysis, of which 13 (76%) were Xpert-positive. CONCLUSIONS Pooling of sputum samples using Xpert achieved reasonable sensitivity and warrants further evaluation of the systematic screening of high TB prevalence populations.
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Affiliation(s)
- V Zishiri
- The Aurum Institute, Johannesburg, South Africa
| | - V Chihota
- The Aurum Institute, Johannesburg, South Africa
| | - K McCarthy
- The Aurum Institute, Johannesburg, South Africa
| | | | - G J Churchyard
- The Aurum Institute, Johannesburg, South Africa; School of Public Health, University of Witwatersrand, Johannesburg, South Africa
| | - C J Hoffmann
- The Aurum Institute, Johannesburg, South Africa; Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
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Hoffmann CJ, Dayal D, Cheyip M, McIntyre JA, Gray GE, Conway S, Martinson NA. Prevalence and associations with hepatitis B and hepatitis C infection among HIV-infected adults in South Africa. Int J STD AIDS 2013; 23:e10-3. [PMID: 23104758 DOI: 10.1258/ijsa.2009.009340] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
We assessed prevalence and factors associated with hepatitis B in a cross section of HIV-infected primary care and antinatal clinic patients in South Africa and evaluated a rapid hepatitis B surface antigen (HBsAg) assay. We enrolled 998 patients; 88% were women, median age was 29 years and median CD4 count was 354 cells/mm(3). HBsAg enzyme-linked immunosorbent assay (ELISA), anti-hepatitis B core (HBc) antibodies and hepatitis C virus antibody were positive among 4.2%, 37% and 0.1% of subjects, respectively. Univariate and multivariate associations were assessed using logistic regression. Anti-HBc antibodies were associated with alcohol use, traditional medicines and higher CD4 counts; HBsAg positivity was associated with lower CD4. Compared with the HBsAg ELISA, a rapid HBsAg test had a sensitivity of 75.0% and specificity of 99.6%. In conclusion, we identified a moderate prevalence of both HBsAg and anti-HBc. Importantly, we found that subjects with HBsAg positivity had lower CD4 counts.
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Affiliation(s)
- C J Hoffmann
- Perinatal HIV Research Unit, University of the Witwatersrand, Johannesburg, South Africa.
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10
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Abstract
Emphysematous cystitis is an uncommon condition in which pockets of gas are formed in and around the bladder wall by gas-forming organisms. Persons with diabetes, neurogenic bladder and chronic urinary infection are predisposed to the disease. Severity of illness ranges from an asymptomatic condition to life-threatening cystitis. We present 2 cases of emphysematous cystitis. One case was an incidental finding on evaluation of abdominal discomfort with resolution upon removal of predisposing factors. The other patient presented with an acute abdomen that progressed to severe necrotizing cystitis ultimately requiring cystectomy. The initial involvement of the urologist as a consultant is emphasized. A complete review of the literature describes the incidence, various presentations, associated diseases and organisms, pathogenesis, and available methods for diagnosis and treatment reported for this disease. Successful management depends on early diagnosis with correction of underlying causes, administration of appropriate antibiotics, establishment of adequate bladder drainage and surgical excision of involved tissue when required. Early detection and prompt treatment are encouraged.
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Affiliation(s)
- H J Quint
- Department of Surgery, University of Arizona, Tucson
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Haeffner EW, Seibicke S, Hoffmann CJ. Altered 5'-nucleotidase specific activity and distribution between two plasma membrane domains of ascites tumor cells with modified lipid composition. Int J Biochem 1988; 20:55-60. [PMID: 2830154 DOI: 10.1016/0020-711x(88)90010-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
1. The cholesterol and phospholipid content of the surface membranes of ascites tumor cells cultivated in lipid-depleted medium was reduced to about 60(70)% of the control, but the relative composition of the individual phospholipids was not altered. 2. Differences in lipid composition were also observed between the two plasma membrane domains isolated from the cells cultured in normal and lipid-depleted medium respectively. 3. The fatty acid spectrum of the lipid-depleted membranes showed a greater fraction of saturated vs unsaturated acids. 4. The membrane lipid fluidity measured by fluorescence polarization was decreased in the modified surface membranes. 5. The 5'-nucleotidase specific activity was drastically reduced (46-66%) in the lipid-deleted membranes, and in addition its distribution between the two vesicle fractions was altered.
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Affiliation(s)
- E W Haeffner
- Institute of Cell and Tumor Biology, German Cancer Research Center, Heidelberg, F.R.G
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Haeffner EW, Zimmermann HP, Hoffmann CJ. Influence of triethyl lead on the activity of enzymes of the ascites tumor cell plasma membrane and its microviscosity. Toxicol Lett 1984; 23:183-8. [PMID: 6150565 DOI: 10.1016/0378-4274(84)90124-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The influence of triethyl lead (TriEL) on the activity of plasma membrane-bound enzymes of Ehrlich ascites tumor cells and on membrane fluidity has been investigated. TriEL completely inhibits the (Na+-K+)-ATPase in its membrane-bound and even more pronounced in its solubilized form between 5 and about 20 microM. It also alters the microviscosity of the isolated plasma membrane up to a temperature of about 30 degrees C, but it does not have any influence on the fluidity of the membrane-derived liposomes. From these data it is concluded that the inhibitor may interact directly with the catalytic subunit of the (Na+ + K+)-ATPase, and may not exert its influence by interfering with the membrane lipids.
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Haeffner EW, Hoffmann CJ, Stoehr M, Scherf H. Cholesterol-induced growth stimulation, cell aggregation, and membrane properties of ascites tumor cells in culture. Cancer Res 1984; 44:2668-76. [PMID: 6722800] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Ascites tumor cells can be cultivated at a reduced serum concentration if cholesterol (2.50 mg per 100 ml of medium) is added to the culture medium. At serum concentrations of 3%, optimal growth properties are obtained; below 3%, cell cultures usually perish after a few days. Cells grown in the presence of added cholesterol have an elevated content of this molecule per cell as well as in the plasma membrane, and they also show a cholesterol concentration-dependent rate of proliferation. Precursors of the cholesterol-biosynthetic pathway like mevalonic acid, added in mM amounts, or squalene and lanosterol cannot be substituted for cholesterol itself. This is due to the observation that the biosynthetic pathway is blocked at the stage of lanosterol conversion to cholesterol. Cholesterol de novo synthesis from acetate is regulated by the cholesterol content of the cells, which also affects the production of ubiquinone and dolichol. Growth factors such as insulin, prostaglandin F2 alpha, and transferrin added to the medium do not mimic the cholesterol-induced effect. Distribution of DNA during cell cycle and the cell density-dependent reduction in macromolecule synthesis is very similar to the control cells. In contrast, cells without added cholesterol show reduced growth properties accompanied by the accumulation of cells in the mitotic and G2 phase. The cholesterol/phospholipid ratio of the plasma membranes of cholesterol-rich cells is about 15% lower than of the control cells and 40% higher compared to the cholesterol-poor cells, which, however, does not significantly alter the membrane fluidity between the cholesterol-rich and -poor cells as revealed by fluorescence polarization measurements. The most dramatic behavior of the cholesterol-rich cells is their tendency to form aggregates, which is demonstrated either by concanavalin A-induced agglutination or by cell density-dependent aggregation shown by interference microscopy in vivo.
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14
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Hoffmann CJ, Paweletz N, Friedel R, Haeffner EW. Structural and functional alterations of lipid-depleted ascites tumor cells in culture. Eur J Cell Biol 1984; 33:66-74. [PMID: 6538135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Ascites tumor cells growth-arrested in lipid-depleted medium were modified with respect to their lipid composition, i.e. mainly cholesterol and the phospholipid fraction. These so-called lipid-depleted cells were generally smaller, had a surface area reduced by 55% compared to the control cells and had an altered cell surface architecture with large parts being smooth, interrupted by isolated bundles of microvilli and blebs as revealed by scanning electron microscopy. This deorganization process of the cells. Lectin-induced agglutination and receptor binding capacity was reduced, and also the receptor distribution was changed resulting in a cap-like formation on the surface as shown with FITC-labelled concanavalin A. The reduction in lipid content yielding a lower C/P ratio profoundly decreased the plasma membrane fluidity which was determined by fluorescence polarization measurements. Studies on fatty acid and cholesterol de novo synthesis revealed only small increases under lipid-free conditions not sufficient to meet the requirements of the lipid-depleted cells for these substances. It is therefore concluded that ascites tumor cells need exogenous preformed lipids for adequate functioning of the cell.
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15
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Haeffner EW, Hoffmann CJ. Direct quantitation of free cholesterol in total serum lipid extracts by computer-assisted gas--liquid chromatography. J Chromatogr 1982; 228:268-72. [PMID: 7076748 DOI: 10.1016/s0378-4347(00)80439-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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