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BACKGROUND: Cervical cancer poses a significant burden, particularly in low-and-middle income countries (LMIC) with limited access to healthcare. High-income countries have made progress in prevention, while LMIC face unacceptably high incidence and mortality rates, often lacking official screening recommendations. We analysed the presence and content of cervical cancer screening guidelines for the secondary prevention of cervical cancer in the Southern African Development Community (SADC) and compared it to the current World Health Organization (WHO) guidelines for screening and treatment of cervical pre-cancer lesions for cervical cancer prevention. METHODS: A review of national cervical cancer guidelines across the SADC region was conducted. Data was obtained from government websites, international cancer control platforms, and WHO resources. Search terms included "cervical cancer" and "cervical cancer control guidelines", amongst others. There were no limitations on publication years, and the most recent versions of the guidelines were analysed, regardless of language. Each guideline was assessed for specific screening and treatment recommendations, in relation to the current WHO guidelines. Points were assigned for each data element. RESULTS: While most countries contributed data to this analysis there was a notable absence of adherence to the WHO guidelines. The most common screening method was naked eye visual inspection. There was a consensus on the age of screening initiation. Most countries recommended treatment by cryotherapy and loop excision. CONCLUSION: Effective cervical cancer screening programmes, guided by evidence-based recommendations, can enhance early intervention and outcomes. This study highlights the need for standardized and evidence-based cervical cancer screening guidelines in the SADC region, to reduce the burden of cervical cancer and improve the health outcomes of women in these areas.
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Detección Precoz del Cáncer , Neoplasias del Cuello Uterino , Humanos , Neoplasias del Cuello Uterino/diagnóstico , Neoplasias del Cuello Uterino/prevención & control , Femenino , África Austral/epidemiología , Guías de Práctica Clínica como Asunto , Tamizaje Masivo , Adulto , Organización Mundial de la SaludAsunto(s)
Laboratorios , Mycobacterium tuberculosis , Humanos , Sudáfrica , Recolección de Muestras de SangreRESUMEN
BACKGROUND: Human papillomavirus (HPV)-based primary screening guidelines are based on screening test performance and prevalence data generated in high-resource areas with low HIV infection rates. There is an urgent need for local data on infection and disease prevalence, as well as screening test performance, among both HIV-positive and HIV-negative South African (SA) women, in order to inform updated screening guidelines. Objectives. This study describes the baseline characteristics of participants in the cross-sectional phase of the multicentric DIAgnosis in Vaccine And Cervical Cancer Screen (DiaVACCS) screening trial. The objective was to determine the prevalence of positive screening and pre-invasive disease using different tests and strategies in the SA HIV-positive and HIV-negative population. METHODS: A total of 1 104 women aged 25 - 65 years and eligible for screening were included, 465 HIV positive and 639 HIV negative. Visual inspection and molecular and cytological screening tests were done on self-sampled and healthcare worker-collected specimens. All participants who screened positive and 49.1% of those who screened negative were invited for colposcopy and biopsy, and those qualifying for treatment were recalled for large loop excision of the transformation zone as part of the trial. The worst histology result for each participant was used, and for untested women, multiple imputation was used to estimate verification biasadjusted histology values. RESULTS: Visual inspection was positive in 50.4% of HIV-positive v. 20.9% of HIV-negative women, cytology (atypical squamous cells of undetermined significance) in 39.9% v. 17.0%, and high-risk HPV DNA in 41.2% v. 19.6%. Overall, high-grade squamous intraepithelial lesion-positive cytology peaked in the age group 30 - 39 years at 16.7%. After adjustment for verification bias, histological diagnosis of cervical intraepithelial neoplasia (CIN)2+ was suspected in 44.7% v. 23.5% and CIN3+ in 23.3% v. 10.2% of HIV-positive and negative women, respectively. Invasive cancer was diagnosed in 15 women (1.95% of histological studies performed), and verification bias adjustment suggested 20 cases (1.8% of the study population). CONCLUSION: The baseline findings from the DiaVACCS trial confirm a high prevalence of HPV-related cervical pathology in the SA HIV-negative screening population, showing a clear need to reach these women with a screening programme. Among HIV-positive women, prevalence values were almost doubled. The prevalence of existing invasive cervical cancer was 1 - 2% of all women. Further analysis of the performance of single and multiple screening tests between the two subgroups will contribute to the choice of the most effective strategies to identify women at risk of developing invasive cancer.
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Infecciones por VIH , Infecciones por Papillomavirus , Neoplasias del Cuello Uterino , Vacunas , Estudios Transversales , Demografía , Detección Precoz del Cáncer/métodos , Femenino , Infecciones por VIH/diagnóstico , Infecciones por VIH/epidemiología , Humanos , Tamizaje Masivo/métodos , Papillomaviridae/genética , Infecciones por Papillomavirus/complicaciones , Infecciones por Papillomavirus/diagnóstico , Infecciones por Papillomavirus/epidemiología , Sudáfrica/epidemiología , Neoplasias del Cuello Uterino/diagnóstico , Neoplasias del Cuello Uterino/epidemiología , Neoplasias del Cuello Uterino/patología , Frotis VaginalRESUMEN
Current ecological understanding of plants with underground storage organs (USOs) suggests they have, in general, low rates of recruitment and thus as a resource it should be rapidly exhausted, which likely had implications for hunter-gatherer mobility patterns. We focus on the resilience (defined here as the ability of species to persist after being harvested) of USOs to human foraging. Human foragers harvested all visible USO material from 19 plots spread across six Cape south coast (South Africa) vegetation types for three consecutive years (2015-2017) during the period of peak USO apparency (September-October). We expected the plots to be depleted after the first year of harvesting since the entire storage organ of the USO is removed during foraging, i.e. immediate and substantial declines from the first to the second harvest. However, over 50% of the total weight harvested in 2015 was harvested in 2016 and 2017; only after two consecutive years of harvesting, was there evidence of significantly lower yield (p = 0.034) than the first (2015) harvest. Novel emergence of new species and new individuals in year two and three buffered the decline of harvested USOs. We use our findings to make predictions on hunter-gatherer mobility patterns in this region compared to the Hadza in East Africa and the Alyawara in North Australia.
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Plantas , Humanos , Sudáfrica , África Oriental , AustraliaRESUMEN
BACKGROUND: The impact of SARS-CoV-2 infection in pregnant women living with HIV (PLHIV) has not been described previously. OBJECTIVES: To describe the clinical presentation and outcomes of a cohort of women with high-risk pregnancies with confirmed COVID-19 to determine whether risk factors for disease severity and adverse outcomes of COVID-19 differed in pregnant women without HIV compared with PLHIV. METHODS: We prospectively enrolled pregnant women with COVID-19 attending the high-risk obstetric service at Tygerberg Hospital, Cape Town, South Africa, from 1 May to 31 July 2020, with follow-up until 31 October 2020. Women were considered high risk if they required specialist care for maternal, neonatal and/or anaesthetic conditions. Common maternal or obstetric conditions included hypertensive disorders, morbid obesity (body mass index (BMI) ≥40 kg/m2) and diabetes. Information on demographics, clinical features, and maternal and neonatal outcomes was collected and compared for PLHIV v. pregnant women without HIV. RESULTS: One hundred women (72 without HIV and 28 PLHIV) with high-risk pregnancies had laboratory-confirmed COVID-19. Among the 28 PLHIV, the median (interquartile range) CD4 count was 441 (317 - 603) cells/µL, and 19/26 (73%) were virologically suppressed. COVID-19 was diagnosed predominantly in the third trimester (81%). Obesity (BMI ≥30 in n=61/81; 75%) and hypertensive disorders were frequent comorbidities. Of the 100 women, 40% developed severe or critical COVID-19, 15% required intensive care unit admission and 6% needed invasive ventilation. Eight women died, 1 from advanced HIV disease complicated by bacteraemia and urosepsis. The crude maternal mortality rate was substantially higher in women with COVID-19 compared with all other deliveries at our institution during this period (8/91 (9%) v. 7/4 058 (0.2%); p<0.001). Neonatal outcomes were favourable. No significant differences in COVID-19 risk factors, disease severity, and maternal/neonatal outcome were noted for PLHIV v. those without HIV. CONCLUSIONS: In this cohort of high-risk pregnant women, the impact of COVID-19 was severe, significantly increasing maternal mortality risk compared with baseline rates. Virally suppressed HIV infection was not associated with worse COVID-19 outcomes in pregnancy.
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COVID-19/complicaciones , Infecciones por VIH/epidemiología , Complicaciones Infecciosas del Embarazo/epidemiología , Resultado del Embarazo , Adulto , Recuento de Linfocito CD4 , Estudios de Cohortes , Femenino , Humanos , Recién Nacido , Mortalidad Materna , Embarazo , Complicaciones Infecciosas del Embarazo/virología , Embarazo de Alto Riesgo , Estudios Prospectivos , SudáfricaAsunto(s)
Tuberculosis Resistente a Múltiples Medicamentos , Antituberculosos/uso terapéutico , Humanos , Tuberculosis Resistente a Múltiples Medicamentos/tratamiento farmacológico , Tuberculosis Resistente a Múltiples Medicamentos/epidemiología , Tuberculosis Resistente a Múltiples Medicamentos/prevención & controlAsunto(s)
Consumo de Bebidas Alcohólicas/efectos adversos , Complicaciones del Embarazo/etiología , Efectos Tardíos de la Exposición Prenatal/etiología , Fumar/efectos adversos , Adulto , Femenino , Humanos , Embarazo , Complicaciones del Embarazo/epidemiología , Resultado del Embarazo/epidemiología , Efectos Tardíos de la Exposición Prenatal/epidemiología , Efectos Tardíos de la Exposición Prenatal/prevención & controlRESUMEN
BACKGROUND: An increase in vulvar cancer in young women is attributed to infection with oncogenic human papillomavirus (HPV). South Africa (SA) has a high prevalence of HPV, and it was therefore hypothesised that women with vulvar cancer here would be younger than in high-income countries (HICs). OBJECTIVE: To describe age, cancer stage, treatment and outcome of patients with vulvar cancer at a tertiary referral centre in SA. METHODS: In a retrospective observational study, patient records of women diagnosed with vulvar cancer between 2001 and 2014 were reviewed and demographic and surgical details captured. Histology results of vulvar biopsies and resected specimens were checked for HPV changes, koilocytes and usual-type vulval intraepithelial neoplasia. Patients were restaged using the International Federation of Gynecology and Obstetrics (FIGO) 2009 staging system to allow for comparison of outcomes. Five-year disease-specific survival probability curves were generated using Kaplan-Meier analysis. RESULTS: The mean age of the 180 patients in the study was 52.5 years. Those who had documented HPV changes on histological specimens had a mean age of 50.4 years. More than 50% of the patients had advanced-stage disease, and 62.7% were treated with primary surgery. Five-year disease-specific survival probabilities were similar to those reported in the literature. CONCLUSIONS: Vulvar cancer should not be regarded as a disease of the elderly in SA, as women with vulvar cancer are 10 - 15 years younger than in HICs. A large proportion of patients present with advanced-stage disease. Health professionals should be alert to vulvar lesions, especially in women with abnormal Pap smears, to reduce the morbidity and mortality of this disease.
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ETHNOPHARMACOLOGICAL RELEVANCE: Extracts of plant species, used traditionally to treat malaria, have been extensively investigated for their activity against Plasmodium intraerythrocytic asexual parasites in search of new antimalarial drugs. However, less effort has been directed towards examining their efficacy in blocking transmission. Here, we report the results of the in vitro screening of extracts from eight selected plant species used traditionally to treat malaria in South Africa for activity against Plasmodium falciparum NF54 early and late stage gametocytes. The species used were Khaya anthotheca, Trichilia emetica, Turraea floribunda, Leonotis leonurus, Leonotis leonurus ex Hort, Olea europaea subsp. Africana, Catha edulis and Artemisia afra. AIM OF THE STUDY: To investigate the activities of extracts from plant species traditionally used for malaria treatment against P. falciparum gametocytes. MATERIAL AND METHODS: Air-dried and ground plant leaves were extracted using acetone. Primary two point in vitro phenotypic screens against both early and late stage gametocytes were done at 10 and 20µg/ml followed by full IC50 determination of the most active extracts. Inhibition of gametocyte viability in vitro was assessed using the parasite lactate dehydrogenase (pLDH) assay. RESULTS: Of the eight crude acetone extracts from plant species screened in vitro, four had good activity with over 50-70% inhibition of early and late stage gametocytes' viability at 10 and 20µg/ml, respectively. Artemisia afra (Asteraceae), Trichilia emetica (Meliaceae) and Turraea floribunda (Meliaceae) were additionally highly active against both gametocyte stages with IC50 values of less than 10µg/ml while Leonotis leonurus ex Hort (Lamiaceae) was moderately active (IC50<20µg/ml). The activity of these three highly active plant species was significantly more pronounced on late stage gametocytes compared to early stages. CONCLUSION: This study shows the potential transmission blocking activity of extracts from selected South African medicinal plants and substantiates their traditional use in malaria control that broadly encompasses prevention, treatment and transmission blocking. Further studies are needed to isolate and identify the active principles from the crude extracts of A. afra, T. emetica and T. floribunda, as well as to examine their efficacy towards blocking parasite transmission to mosquitoes.
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Antimaláricos/farmacología , Supervivencia Celular/efectos de los fármacos , Medicina Tradicional , Extractos Vegetales/farmacología , Plasmodium falciparum/efectos de los fármacos , Antimaláricos/química , Evaluación Preclínica de Medicamentos , Extractos Vegetales/química , SudáfricaRESUMEN
BACKGROUND: Cervical cancer is a preventable disease with a high prevalence in South Africa (SA), where screening is opportunistic. Primary prevention is now possible through HPV vaccination. In VACCS 1 the feasibility of linking cervical cancer with HPV vaccination was demonstrated. OBJECTIVES: To investigate the feasibility of linking HPV self-testing with a two-dose HPV vaccination schedule and to compare results with VACCS 1. METHODS: The project was conducted in five schools in the South-West District of Tshwane, Gauteng, SA. Leaflet information on cervical cancer and screening was provided, with requests for consent and assent for a two-dose HPV vaccination of schoolgirls. Female caregivers were invited to take part in HPV self-screening. RESULTS: Of 965 girls invited for vaccination, 519 (53.7%) had full consent and 518 (99.8%) received at least one vaccine dose. The invited uptake rate was 53.7% and 495 girls received both doses, giving a completion rate of 95.4% v. 82.6% in VACCS 1. Of 1 135 self-screen kits handed out, 560 (49.3%) were not returned. The mean age (standard deviation) of the 160 women who participated in self-screening was 38.7 (7.7) years. HPV testing was negative in 116 women (72.5%), 15 women (9.4%) tested positive for HPV 16 and/or 18, and 27 (16.9%) were positive for non-16/18 oncogenic HPV. CONCLUSION: Data from the VACCS projects suggest that school-based vaccine programmes can be successfully implemented. A two-dose schedule allowed for higher completion rates. Linking self-collected HPV screening to HPV vaccination is feasible, is a promising and viable screening strategy, and reached the appropriate age group for screening.
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Detección Precoz del Cáncer/métodos , Infecciones por Papillomavirus/prevención & control , Vacunas contra Papillomavirus/administración & dosificación , Neoplasias del Cuello Uterino/prevención & control , Adulto , Factores de Edad , Anciano , Niño , Estudios de Factibilidad , Femenino , Humanos , Esquemas de Inmunización , Persona de Mediana Edad , Papillomaviridae/aislamiento & purificación , Infecciones por Papillomavirus/complicaciones , Infecciones por Papillomavirus/diagnóstico , Prevención Primaria/métodos , Instituciones Académicas , Sudáfrica , Neoplasias del Cuello Uterino/virología , Vacunación/métodos , Adulto JovenRESUMEN
Cisplatin is used as a cytotoxic agent for the management of cervical cancer. However, the severity of the side-effects limits the use of this drug, particularly at high doses. Resistance to cisplatin is often attributed to a disruption in the normal apoptotic response via aberrant activation of pathways such as the mTOR pathway. Here we assess the role of mTOR and its effect on cell death sensitization and autophagy in response to a low concentration of cisplatin in cervical cancer cells. Additionally we measured the expression profile of mTOR in normal, low- and high-grade squamous intraepithelial (LSIL and HSIL) lesions and cancerous tissue. An in vitro model of cervical cancer was established using HeLa and CaSki cells. mTOR protein expression as well as autophagy-related proteins were evaluated through Western blotting. Inhibition of mTOR was achieved with the use of rapamycin and RNA silencing. A low concentration of cisplatin administered as a single agent induces autophagy, but not apoptosis. Cisplatin cytotoxicity was greatly enhanced in cancer cells when mTOR had been inhibited prior to cisplatin treatment which was likely due to autophagy being increased above cisplatin-induced levels, thereby inducing apoptosis. Cervical tissue samples revealed an increase in mTOR protein expression in LSIL and carcinoma tissue which suggests a change in autophagy control. Our data suggest that utilising a lower dose of cisplatin combined with mTOR inhibition is a viable treatment option and addresses the challenge of cisplatin dose-dependent toxicity, however future studies are required to confirm this in a clinical setting.
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Antineoplásicos/farmacología , Autofagia/efectos de los fármacos , Cisplatino/farmacología , Lesiones Intraepiteliales Escamosas de Cuello Uterino/enzimología , Serina-Treonina Quinasas TOR/metabolismo , Neoplasias del Cuello Uterino/enzimología , Antineoplásicos/toxicidad , Protocolos de Quimioterapia Combinada Antineoplásica/farmacología , Apoptosis/efectos de los fármacos , Ciclo Celular/efectos de los fármacos , Cisplatino/toxicidad , Relación Dosis-Respuesta a Droga , Femenino , Regulación Neoplásica de la Expresión Génica , Células HeLa , Humanos , Inhibidores de Proteínas Quinasas/farmacología , Interferencia de ARN , Transducción de Señal/efectos de los fármacos , Sirolimus/farmacología , Lesiones Intraepiteliales Escamosas de Cuello Uterino/genética , Lesiones Intraepiteliales Escamosas de Cuello Uterino/patología , Serina-Treonina Quinasas TOR/antagonistas & inhibidores , Serina-Treonina Quinasas TOR/genética , Transfección , Neoplasias del Cuello Uterino/patologíaAsunto(s)
Tamizaje Masivo/métodos , Infecciones por Papillomavirus/prevención & control , Vacunas contra Papillomavirus/administración & dosificación , Neoplasias del Cuello Uterino/prevención & control , Vacunación/métodos , Adolescente , Adulto , Niño , Femenino , Humanos , Incidencia , Infecciones por Papillomavirus/complicaciones , Sudáfrica/epidemiología , Neoplasias del Cuello Uterino/epidemiología , Neoplasias del Cuello Uterino/virologíaRESUMEN
BACKGROUND: The incidence of cervical cancer in South Africa (SA) remains high, and the current screening programme has had limited success. New approaches to prevention and screening tactics are needed. OBJECTIVES: To investigate acceptance of school-based human papillomavirus (HPV) vaccination, as well as the information provided, methods of obtaining consent and assent, and completion rates achieved. METHODS: Information on cervical cancer and HPV vaccination was provided to 19 primary schools in Western Cape and Gauteng provinces participating in the study. Girls with parental consent and child assent were vaccinated during school hours at their schools. RESULTS: A total of 3 465 girls were invited to receive HPV vaccine, of whom 2 046 provided written parental consent as well as child assent. At least one dose of vaccine was delivered to 2 030 girls (99.2% of the consented cohort), while a total of 1 782 girls received all three doses. Sufficient vaccination was achieved in 91.6% of the vaccinated cohort. Of all invited girls, 56.9% in Gauteng and 50.7% in the Western Cape were sufficiently vaccinated. CONCLUSION: This implementation project demonstrated that HPV vaccination is practical and safe in SA schools. Political and community acceptance was good, and positive attitudes towards vaccination were encountered. During the study, which mimicked a governmental vaccine roll-out programme, high completion rates were achieved in spite of several challenges encountered.
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Infecciones por Papillomavirus/prevención & control , Vacunas contra Papillomavirus/administración & dosificación , Aceptación de la Atención de Salud , Neoplasias del Cuello Uterino/prevención & control , Vacunación/métodos , Niño , Femenino , Humanos , Infecciones por Papillomavirus/complicaciones , Consentimiento Paterno , Instituciones Académicas , Sudáfrica , Neoplasias del Cuello Uterino/virología , Vacunación/estadística & datos numéricosRESUMEN
ACCESSIBLE SUMMARY: In the previous paper we described a model explaining differences in rates of conflict and containment between wards, grouping causal factors into six domains: the staff team, the physical environment, outside hospital, the patient community, patient characteristics and the regulatory framework. This paper reviews and evaluates the evidence for the model from previously published research. The model is supported, but the evidence is not very strong. More research using more rigorous methods is required in order to confirm or improve this model. ABSTRACT: In a previous paper, we described a proposed model explaining differences in rates of conflict (aggression, absconding, self-harm, etc.) and containment (seclusion, special observation, manual restraint, etc.). The Safewards Model identified six originating domains as sources of conflict and containment: the patient community, patient characteristics, the regulatory framework, the staff team, the physical environment, and outside hospital. In this paper, we assemble the evidence underpinning the inclusion of these six domains, drawing upon a wide ranging review of the literature across all conflict and containment items; our own programme of research; and reasoned thinking. There is good evidence that the six domains are important in conflict and containment generation. Specific claims about single items within those domains are more difficult to support with convincing evidence, although the weight of evidence does vary between items and between different types of conflict behaviour or containment method. The Safewards Model is supported by the evidence, but that evidence is not particularly strong. There is a dearth of rigorous outcome studies and trials in this area, and an excess of descriptive studies. The model allows the generation of a number of different interventions in order to reduce rates of conflict and containment, and properly conducted trials are now needed to test its validity.
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Control de la Conducta/normas , Conflicto Psicológico , Hospitales Psiquiátricos/normas , Modelos de Enfermería , Enfermería Psiquiátrica/normas , Adulto , Femenino , Humanos , Masculino , Investigación Metodológica en EnfermeríaRESUMEN
To determine factors that influence excision treatment outcome and recurrence of cervical squamous intraepithelial lesions (SIL) in women living with HIV infection, we analysed 1848 women who underwent excision treatment of cervical SIL at Tygerberg Hospital, Cape Town, South Africa. We compared treatment failure defined as presence of cervical intraepithelial neoplasia (CIN) I (presence of CIN I or higher at first follow-up after excision treatment) and post-excision recurrence of lesions (at one year or later) between women of HIV-positive, -negative or unknown status and examined factors associated with excision treatment outcome and recurrence. HIV-infected women experienced higher treatment failure than uninfected women (53.8% versus 26.9%, P < 0.001). At treatment failure, more HIV-infected women had low-grade squamous intraepithelial lesion (LSIL) compared with uninfected women (64.9% versus 37.3%, P < 0.001). Treatment failure did not differ with the type of excision used in HIV-infected women. HIV-infected women were more likely to experience recurrence of lesions after excision treatment than uninfected women (hazard ratio 1.95, 95% confidence interval [CI] 1.59-2.39; P < 0.001). Antiretroviral therapy (ART) initiated before excision biopsy had a strong protective effect against recurrence (hazard ratio 0.70, 95% CI 0.55-0.89; P = 0.006). Our data suggest that women with cervical SIL initiated on ART earlier may be expected to have better long-term excision treatment outcome. Close follow-up should be maintained after cervical excision treatment, especially in a setting of high HIV prevalence.
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Antirretrovirales/administración & dosificación , Infecciones por VIH/complicaciones , Infecciones por VIH/tratamiento farmacológico , Displasia del Cuello del Útero/complicaciones , Displasia del Cuello del Útero/virología , Neoplasias del Cuello Uterino/cirugía , Neoplasias del Cuello Uterino/virología , Adulto , Estudios de Cohortes , Femenino , Infecciones por VIH/epidemiología , Humanos , Estimación de Kaplan-Meier , Recurrencia , Estudios Retrospectivos , Sudáfrica/epidemiología , Estadísticas no Paramétricas , Resultado del Tratamiento , Neoplasias del Cuello Uterino/epidemiología , Displasia del Cuello del Útero/epidemiologíaAsunto(s)
Antibacterianos/uso terapéutico , Infecciones Bacterianas/tratamiento farmacológico , Farmacorresistencia Bacteriana , Promoción de la Salud/organización & administración , Medicamentos bajo Prescripción/uso terapéutico , Atención Primaria de Salud/organización & administración , Infecciones Bacterianas/epidemiología , Humanos , Programas Nacionales de Salud/organización & administración , SudáfricaAsunto(s)
Control de Enfermedades Transmisibles/métodos , Enfermedades Transmisibles/epidemiología , Farmacorresistencia Bacteriana , Promoción de la Salud/organización & administración , Vigilancia de Guardia , Antibacterianos/uso terapéutico , Enfermedades Transmisibles/tratamiento farmacológico , Humanos , Programas Nacionales de Salud/organización & administración , SudáfricaRESUMEN
Extensive structural and functional remodelling of Plasmodium falciparum (malaria)-infected erythrocytes follows the export of a range of proteins of parasite origin (exportome) across the parasitophorous vacuole into the host erythrocyte. The genome of P. falciparum encodes a diverse chaperone complement including at least 43 members of the heat shock protein 40kDa (Hsp40) family, and six members of the heat shock protein 70kDa (Hsp70) family. Nearly half of the Hsp40 proteins of P. falciparum are predicted to contain a PEXEL/HT (Plasmodium export element/host targeting signal) sequence motif, and hence are likely to be part of the exportome. In this review we critically evaluate the classification, sequence similarity and clustering, and possible interactors of the P. falciparum Hsp40 chaperone machinery. In addition to the types I, II and III Hsp40 proteins all exhibiting the signature J-domain, the P. falciparum genome also encodes a number of specialized Hsp40 proteins with a J-like domain, which we have categorized as type IV Hsp40 proteins. Analysis of the potential P. falciparum Hsp40 protein interaction network revealed connections predominantly with cytoskeletal and membrane proteins, transcriptional machinery, DNA repair and replication machinery, translational machinery, the proteasome and proteolytic enzymes, and enzymes involved in cellular physiology. Comparison of the Hsp40 proteins of P. falciparum to those of other apicomplexa reveals that most of the proteins (especially the PEXEL/HT-containing proteins) are unique to P. falciparum. Furthermore, very few of the P. falciparum Hsp40 proteins have human homologs, except for those proteins implicated in fundamental biological processes. Our analysis suggests that P. falciparum has evolved an expanded and specialized Hsp40 protein machinery to enable it successfully to invade and remodel the human erythrocyte, and we propose a model in which these proteins are involved in chaperone-mediated translocation, folding, assembly and regulation of parasite and host proteins.
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Apicomplexa/fisiología , Proteínas del Choque Térmico HSP40/fisiología , Interacciones Huésped-Parásitos/genética , Chaperonas Moleculares/fisiología , Plasmodium falciparum/fisiología , Animales , Apicomplexa/genética , Secuencia Conservada , Eritrocitos/metabolismo , Evolución Molecular , Proteínas del Choque Térmico HSP40/clasificación , Proteínas del Choque Térmico HSP40/genética , Proteínas del Choque Térmico HSP40/metabolismo , Proteínas HSP70 de Choque Térmico/metabolismo , Humanos , Modelos Biológicos , Filogenia , Plasmodium falciparum/genética , Unión Proteica , Homología de Secuencia de AminoácidoRESUMEN
Both prokaryotic and eukaryotic cells contain multiple heat shock protein 40 (Hsp40) and heat shock protein 70 (Hsp70) proteins, which cooperate as molecular chaperones to ensure fidelity at all stages of protein biogenesis. The Hsp40 signature domain, the J-domain, is required for binding of an Hsp40 to a partner Hsp70, and may also play a role in the specificity of the association. Through the creation of chimeric Hsp40 proteins by the replacement of the J-domain of a prokaryotic Hsp40 (DnaJ), we have tested the functional equivalence of J-domains from a number of divergent Hsp40s of mammalian and parasitic origin (malarial Pfj1 and Pfj4, trypanosomal Tcj3, human ERj3, ERj5, and Hsj1, and murine ERj1). An in vivo functional assay was used to test the functionality of the chimeric proteins on the basis of their ability to reverse the thermosensitivity of a dnaJ cbpA mutant Escherichia coli strain (OD259). The Hsp40 chimeras containing J-domains originating from soluble (cytosolic or endoplasmic reticulum (ER)-lumenal) Hsp40s were able to reverse the thermosensitivity of E. coli OD259. In all cases, modified derivatives of these chimeric proteins containing an His to Gln substitution in the HPD motif of the J-domain were unable to reverse the thermosensitivity of E. coli OD259. This suggested that these J-domains exerted their in vivo functionality through a specific interaction with E. coli Hsp70, DnaK. Interestingly, a Hsp40 chimera containing the J-domain of ERj1, an integral membrane-bound ER Hsp40, was unable to reverse the thermosensitivity of E. coli OD259, suggesting that this J-domain was unable to functionally interact with DnaK. Substitutions of conserved amino acid residues and motifs were made in all four helices (I-IV) and the loop regions of the J-domains, and the modified chimeric Hsp40s were tested for functionality using the in vivo assay. Substitution of a highly conserved basic residue in helix II of the J-domain was found to disrupt in vivo functionality for all the J-domains tested. We propose that helix II and the HPD motif of the J-domain represent the fundamental elements of a binding surface required for the interaction of Hsp40s with Hsp70s, and that this surface has been conserved in mammalian, parasitic and bacterial systems.