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1.
Med Mycol ; 60(5)2022 May 28.
Artículo en Inglés | MEDLINE | ID: mdl-35604675

RESUMEN

Although a high prevalence of COVID-19-associated pulmonary aspergillosis has been reported, it is still difficult to distinguish between colonization with Aspergillus fumigatus and infection. Concomitantly, similarities between severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and hypersensitivity pneumonitis were suggested. The objective of this study was to investigate retrospectively if precipitin assays targeting A. fumigatus could have been useful in the management of SARS-CoV-2 patients hospitalized in an Intensive Care Unit (ICU) in 2020. SARS-CoV-2 ICU patients were screened for Aspergillus co-infection using biomarkers (galactomannan antigen, qPCR) and culture of respiratory samples (tracheal aspirates and bronchoalveolar lavage). For all these patients, clinical data, ICU characteristics and microbial results were collected. Electrosyneresis assays were performed using commercial A. fumigatus somatic and metabolic antigens. ELISA were performed using in-house A. fumigatus purified antigen and recombinant antigens.Our study population consisted of 65 predominantly male patients, with a median ICU stay of 22 days, and a global survival rate of 62%. Thirty-five patients had at least one positive marker for Aspergillus species detection. The number of arcs obtained by electrosyneresis using the somatic A. fumigatus antigen was significantly higher for these 35 SARS-CoV-2 ICU patients (P 0.01, Welch's t-test). Our study showed that SARS-CoV-2 ICU patients with a positive marker for Aspergillus species detection more often presented precipitins towards A. fumigatus. Serology assays could be an additional tool to assess the clinical relevance of the Aspergillus species in respiratory samples of SARS-CoV-2 ICU patients. LAY SUMMARY: This study showed retrospectively that precipitin assays, such as electrosyneresis, could be helpful to distinguish between colonization and infection with Aspergillus fumigatus during the management of severe acute respiratory syndrome Coronavirus-2 (SARS CoV-2) patients in an intensive care unit.


Asunto(s)
COVID-19 , Aspergilosis Pulmonar Invasiva , Animales , Antígenos Fúngicos , Aspergillus , Aspergillus fumigatus , Biomarcadores , COVID-19/diagnóstico , COVID-19/veterinaria , Femenino , Aspergilosis Pulmonar Invasiva/diagnóstico , Aspergilosis Pulmonar Invasiva/veterinaria , Masculino , Precipitinas , Estudios Retrospectivos , SARS-CoV-2
2.
Med Mycol ; 59(2): 126-138, 2021 Feb 04.
Artículo en Inglés | MEDLINE | ID: mdl-32534456

RESUMEN

Interlaboratory evaluations of Mucorales qPCR assays were developed to assess the reproducibility and performance of methods currently used. The participants comprised 12 laboratories from French university hospitals (nine of them participating in the Modimucor study) and 11 laboratories participating in the Fungal PCR Initiative. For panel 1, three sera were each spiked with DNA from three different species (Rhizomucor pusillus, Lichtheimia corymbifera, Rhizopus oryzae). For panel 2, six sera with three concentrations of R. pusillus and L. corymbifera (1, 10, and 100 genomes/ml) were prepared. Each panel included a blind negative-control serum. A form was distributed with each panel to collect results and required technical information, including DNA extraction method, sample volume used, DNA elution volume, qPCR method, qPCR template input volume, qPCR total reaction volume, qPCR platform, and qPCR reagents used. For panel 1, assessing 18 different protocols, qualitative results (positive or negative) were correct in 97% of cases (70/72). A very low interlaboratory variability in Cq values (SD = 1.89 cycles) were observed. For panel 2 assessing 26 different protocols, the detection rates were high (77-100%) for 5/6 of spiked serum. There was a significant association between the qPCR platform and performance. However, certain technical steps and optimal combinations of factors may also impact performance. The good reproducibility and performance demonstrated in this study support the use of Mucorales qPCR as part of the diagnostic strategy for mucormycosis.


Asunto(s)
Técnicas de Laboratorio Clínico/normas , ADN de Hongos/genética , Técnicas de Diagnóstico Molecular/normas , Mucorales/genética , Mucormicosis/sangre , Mucormicosis/diagnóstico , Reacción en Cadena en Tiempo Real de la Polimerasa/normas , Técnicas de Laboratorio Clínico/instrumentación , Técnicas de Laboratorio Clínico/métodos , Francia , Hospitales Universitarios/estadística & datos numéricos , Humanos , Variaciones Dependientes del Observador , Reproducibilidad de los Resultados
3.
Occup Med (Lond) ; 69(8-9): 632-634, 2019 Dec 31.
Artículo en Inglés | MEDLINE | ID: mdl-31504833

RESUMEN

Hypersensitivity pneumonitis (HP) is a chronic inflammatory lung disease caused by repeated inhalation of antigenic substances. We present a case of metalworking fluids (MWFs)-HP sensitized to Pseudomonas oleovorans in a cystic fibrosis patient. This case illustrates that HP diagnosis remains challenging, especially in patients with another pulmonary disease, and that serodiagnosis contributes to identifying the precise microorganism involved. It also demonstrates that P. oleovorans is an important secondary aetiological agent in MWF-HP, less known than Mycobacterium immunogenum.


Asunto(s)
Alveolitis Alérgica Extrínseca/diagnóstico , Fibrosis Quística/complicaciones , Enfermedades Profesionales/diagnóstico , Adulto , Alveolitis Alérgica Extrínseca/tratamiento farmacológico , Alveolitis Alérgica Extrínseca/etiología , Alveolitis Alérgica Extrínseca/microbiología , Antígenos Bacterianos , Francia , Humanos , Aceites Industriales/microbiología , Masculino , Metalurgia , Enfermedades Profesionales/inmunología , Enfermedades Profesionales/microbiología , Exposición Profesional , Pseudomonas oleovorans/inmunología
5.
Indoor Air ; 24(6): 652-61, 2014 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-24621176

RESUMEN

UNLABELLED: Contrary to hospital exposure, little is known about the indoor fungal exposure of hematology patients at home. The aim of our study was to investigate the mold exposure of hematology patients both at home and at hospital to assess their invasive aspergillosis (IA) risk. Fungal exposure was assessed by quantifying opportunistic molds at hospital during hospitalization and in homes of 53 hematology patients. IA was diagnosed in 13 of 53 patients and invasive fungal infection (IFI) in one patient. In hospital, no opportunistic species, or low levels of opportunistic species, were found in 98% of weekly controls. Only 2% of hematology intensive care unit (ICU) controls showed a high level of Aspergillus fumigatus spores in corridor air. Five patients IA were hospitalized during these periods. Seven dwellings of 53 (5/14 dwellings of patients with IA/IFI and 2/39 dwellings of non-IA patients) had a percentage of A. fumigatus and Aspergillus flavus to total mold (significant predictor variable of IA/IFI in our study, general linear model, P-value = 0.02) as high as 15%. Maintaining a 'zero Aspergillus' goal at hospital is essential, and establishing specific and individually opportunistic mold monitoring at home could help to further reduce the IA risk through continuous surveillance. PRACTICAL IMPLICATIONS: This study emphasizes the fact that preventive measures should not be aimed only at the hospital setting: among patients diagnosed with invasive aspergillosis/invasive fungal infection (IA/IFI), 5 of 14 (36%) were exposed to opportunistic fungal species at home exclusively. Moreover, four of these five patients were living in homes having the highest percentage of Aspergillus fumigatus and Aspergillus flavus (>15%), one of which had 48% of A. fumigatus. Therefore, our work supports the need for a counselor to carry out an environmental survey in patients' homes.


Asunto(s)
Microbiología del Aire , Huésped Inmunocomprometido , Aspergilosis Pulmonar Invasiva/etiología , Adolescente , Adulto , Anciano , Contaminación del Aire Interior/prevención & control , Aspergillus/aislamiento & purificación , Aspergillus/patogenicidad , Preescolar , Monitoreo del Ambiente , Femenino , Hematología , Vivienda , Humanos , Unidades de Cuidados Intensivos , Aspergilosis Pulmonar Invasiva/prevención & control , Masculino , Persona de Mediana Edad , Infecciones Oportunistas/etiología , Infecciones Oportunistas/prevención & control , Factores de Riesgo , Adulto Joven
6.
HNO ; 62(5): 350-7, 2014 May.
Artículo en Alemán | MEDLINE | ID: mdl-24633388

RESUMEN

BACKGROUND: Patients with antiplatelet and antithrombotic therapy (AP/AT) represent a substantial proportion of ear, nose and throat (ENT) patients. Despite the ubiquitous consideration of bleeding and ischemic/thrombembolic risk, no detailed assessment of the perioperative setting in an ENT cohort is available in the literature. OBJECTIVES: The goal of the present work is to give a detailed assessment of patients with AP/AT in an ENT cohort resulting in ENT-specific recommendations for daily routine. MATERIALS AND METHODS: In all, 400 randomized patients were asked regarding analgetic therapy in acute pain. Medical data of 5211 patients who underwent head and neck surgery were analyzed for AP/AT therapy. Therapeutic strategies, the perioperative AP/AT therapy, duration of intensive care treatment and hospitalization (ICT/H), application of erythrocytes and internistic/neurolocigal complication data were analyzed in patients with/without AP/AT. RESULTS: Nearly 75 % of our patients were taking AP/AT due to coronary heart disease (CHD), peripheral arterial disease (PAD), cardiac arrhythmia, or cardiovascular disease (CVD). Patients' questionnaire revealed that 31 % of our patients use acetylsalicylic acid in acute pain, which represents 10 % of the overall AP/AT cohort. Head and neck surgery in patients with AP/AT showed an elevated bleeding frequency (p = 0.006) without an elevated risk for internistic/neurological complications. ICT/H were remarkably prolonged (p = 0.006; p = 0.0004). DISCUSSION: Head and neck surgery in patients with AP/AT can be routinely performed. Indication for intensive care, endotracheal intubation, and tracheostomy should be made generously due to high requirements of airway management in ENT. Ischemic/thrombembolic and bleeding risk requires careful assessment in an interdisciplinary setting.


Asunto(s)
Anticoagulantes/efectos adversos , Anticoagulantes/uso terapéutico , Procedimientos Quirúrgicos Otorrinolaringológicos/efectos adversos , Procedimientos Quirúrgicos Otorrinolaringológicos/estadística & datos numéricos , Inhibidores de Agregación Plaquetaria/uso terapéutico , Hemorragia Posoperatoria/epidemiología , Hemorragia Posoperatoria/etiología , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Niño , Preescolar , Femenino , Alemania/epidemiología , Humanos , Incidencia , Lactante , Masculino , Persona de Mediana Edad , Hemorragia Posoperatoria/prevención & control , Factores de Riesgo , Resultado del Tratamiento , Adulto Joven
7.
J Mycol Med ; 34(4): 101508, 2024 Aug 28.
Artículo en Inglés | MEDLINE | ID: mdl-39216165

RESUMEN

A commercial loop-mediated isothermal amplification (LAMP) assay is available for the detection of Pneumocytis jirovecii (Eazyplex®, Amplex diagnostics, Germany). Few centers currently use this LAMP assay in France. Recently, the commercialization of reagents used to perform the P. jirovecii immunofluorescence assay (IFA) was stopped. This study aimed to assess the position of the commercial LAMP P. jirovecii assay in the diagnostic strategy for Pneumocystis pneumonia. Over 24 months (August 1, 2021, to September 1, 2023), all bronchoalveolar lavage fluid (BALF) samples with a request for P. jirovecii detection were analyzed with the commercial Eazyplex® LAMP assay, using a Genie 2® device (Amplex, diagnostics), in parallel with the techniques used for direct examination. Specific P. jirovecii quantitative real-time PCR (qPCR) was subsequently performed. In total, 346 BALF samples were analyzed by Diff-Quik coloration, IFA, and the commercial Eazyplex® LAMP assay for initial screening. Twenty-six cases of PCP were retained based on radiological, biological and clinical criteria. Among the 26 cases of PCP, 11 BALF samples were positive using the initial screening techniques: four with the three techniques, six by IFA and Eazyplex®, and one only by IFA. The eleven BALF samples were positive with the specific P. jirovecii qPCR assay, with a mean quantification cycle (Cq) of 27 [19-32]. The commercial Eazyplex® LAMP assay is able to provide a result in 25 min and its sensitivity is similar to that of BALF direct examination techniques, such as IFA, which is a technique no longer available on the European market. The sensitivity of the commercial Eazyplex® LAMP assay is however clearly inferior to that of the specific P. jirovecii qPCR assay and, therefore, cannot replace the specific qPCR, but may have a place in the diagnostic strategy.

9.
HNO ; 61(1): 52-4, 2013 Jan.
Artículo en Alemán | MEDLINE | ID: mdl-22532278

RESUMEN

One week after an acute sinusitis, a male patient developed a hypernasal voice, dysphagia, diplopic images, ataxia and paresthesias. He had paresis of the glossopharyngeal and abducens nerves, weakness of the arms and legs, and reflex deficiency. The neurography showed a motor axonal demyelinating neuropathy, so that the diagnosis of Guillain-Barré syndrome was made. After five courses of plasmapheresis, the symptoms improved rapidly.


Asunto(s)
Trastornos de Deglución/diagnóstico , Sinusitis Frontal/diagnóstico , Síndrome de Guillain-Barré/diagnóstico , Enfermedades del Nervio Abducens/diagnóstico , Enfermedades del Nervio Abducens/terapia , Adulto , Trastornos de Deglución/terapia , Diplopía/diagnóstico , Diplopía/terapia , Estudios de Seguimiento , Sinusitis Frontal/terapia , Enfermedades del Nervio Glosofaríngeo/diagnóstico , Enfermedades del Nervio Glosofaríngeo/terapia , Síndrome de Guillain-Barré/terapia , Humanos , Interpretación de Imagen Asistida por Computador , Masculino , Examen Neurológico , Proteínas Nucleares , Plasmaféresis , Proteínas de Unión al ARN , Proteínas Represoras , Tomografía Computarizada por Rayos X , Parálisis de los Pliegues Vocales/diagnóstico , Parálisis de los Pliegues Vocales/terapia , Trastornos de la Voz/diagnóstico , Trastornos de la Voz/terapia
10.
Neurochem Res ; 37(5): 1063-73, 2012 May.
Artículo en Inglés | MEDLINE | ID: mdl-22327943

RESUMEN

Social isolation during postnatal development leads to behavioral and neurochemical changes, and a particular susceptibility of the prefrontal cortex to interventions during this period has been suggested. In addition, some studies showed that consumption of a palatable diet reduces some of the stress effects. Therefore, our aim is to investigate the effect of isolation stress in early life on some parameters of oxidative stress and energy metabolism (Na(+),K(+)-ATPase activity, respiratory chain enzymes activities and mitochondrial mass and potential) in prefrontal cortex of juvenile and adult male rats. We also verified if the consumption of a palatable diet during the prepubertal period would reduce stress effects. The results showed that, in juvenile animals, isolation stress increased superoxide dismutase and Complex IV activities and these effects were still observed in the adulthood. An interaction between stress and diet was observed in catalase activity in juveniles, while only the stress effect was detected in adults, reducing catalase activity. Access to a palatable diet increased Na(+),K(+)-ATPase activity in juveniles, an effect that was reversed after removing this diet. On the other hand, isolation stress induced a decreased activity of this enzyme in adulthood. No effects were observed on glutathione peroxidase, total thiols and free radicals production, as well as on mitochondrial mass and potential. In conclusion, isolation stress in the prepubertal period leads to long-lasting changes on antioxidant enzymes and energetic metabolism in the prefrontal cortex of male rats, and a palatable diet was not able to reverse these stress-induced effects.


Asunto(s)
Corteza Prefrontal/metabolismo , Aislamiento Social , Estrés Psicológico , Animales , Catalasa/metabolismo , Transporte de Electrón , Glutatión Peroxidasa/metabolismo , Masculino , Potenciales de la Membrana , Mitocondrias/metabolismo , Corteza Prefrontal/enzimología , Ratas , Ratas Wistar , ATPasa Intercambiadora de Sodio-Potasio/metabolismo
11.
J Clin Microbiol ; 49(3): 1058-63, 2011 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-21227993

RESUMEN

The aim of the present study was to assess the diagnostic efficacy of a combination of two quantitative Aspergillus PCR assays, targeting a mitochondrial and a ribosomal target, in patients with risk factors for invasive aspergillosis (IA) and positive galactomannan (GM) antigen. Forty-four patients with hematological malignancies and risk factors for IA according to revised European Organization for Research on Treatment of Cancer and the Mycoses Study Group criteria (EORTC/MSG) criteria and presenting at least two sequential GM-positive sera were included in the study. Mitochondrial PCR was carried out prospectively on all GM-positive serum samples. Ribosomal PCR was carried out retrospectively on frozen stored sera. The sensitivities of mitochondrial and ribosomal PCRs were 58% and 50%, respectively. The diagnostic test performance was improved by using a combination of both PCR assays and by considering a patient PCR positive when at least two positive results were obtained. The sensitivity, specificity, and positive and negative likelihood ratios were 65%, 94%, and 11.8 and 0.37, respectively. A significant association between fatal outcome at 90 days and positive results of ribosomal PCR assays was observed (adjusted hazard ratio = 8.2; 95% confidence interval [CI] = 1.0 to 65.8; P = 0.048). Our results showed that the combination of two PCR assays targeting mitochondrial and ribosomal Aspergillus DNA improves the sensitivity of PCR in the diagnosis of IA in hematological patients with risk factors and positive GM results. This study also confirms that a positive PCR result is associated with a poor prognosis in these patients and should lead to specific antifungal therapy being introduced immediately.


Asunto(s)
Aspergillus/aislamiento & purificación , ADN de Hongos/genética , ADN Mitocondrial/genética , ADN Ribosómico/genética , Aspergilosis Pulmonar Invasiva/diagnóstico , Micología/métodos , Reacción en Cadena de la Polimerasa/métodos , Adolescente , Adulto , Anciano , Aspergillus/genética , Niño , ADN de Hongos/aislamiento & purificación , ADN Mitocondrial/aislamiento & purificación , ADN Ribosómico/aislamiento & purificación , Femenino , Galactosa/análogos & derivados , Humanos , Masculino , Mananos/sangre , Persona de Mediana Edad , Sensibilidad y Especificidad , Adulto Joven
12.
Science ; 293(5530): 683-7, 2001 Jul 27.
Artículo en Inglés | MEDLINE | ID: mdl-11474108

RESUMEN

Well-defined constants of radioactive decay are the cornerstone of geochronology and the use of radiogenic isotopes to constrain the time scales and mechanisms of planetary differentiation. Four new determinations of the lutetium-176 decay constant (lambda176Lu) made by calibration against the uranium-lead decay schemes yield a mean value of 1.865 +/- 0.015 x 10(-11) year(-1), in agreement with the two most recent decay-counting experiments. Lutetium-hafnium ages that are based on the previously used lambda176Lu of 1.93 x 10(-11) to 1.94 x 10(-11) year(-1) are thus approximately 4% too young, and the initial hafnium isotope compositions of some of Earth's oldest minerals and rocks become less radiogenic relative to bulk undifferentiated Earth when calculated using the new decay constant. The existence of strongly unradiogenic hafnium in Early Archean and Hadean zircons implies that enriched crustal reservoirs existed on Earth by 4.3 billion years ago and persisted for 200 million years or more. Hence, current models of early terrestrial differentiation need revision.

13.
Lett Appl Microbiol ; 49(2): 260-6, 2009 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-19486284

RESUMEN

AIMS: The aim of our study was to compare, using real-time (Rt) PCR, quantitative levels of five fungal species in three kinds of dwellings. METHODS AND RESULTS: Three groups of homes were recruited: moisture-damaged homes (MDH, n = 30), allergic patient homes (APH, n = 25) and paired control homes (CH, n = 55). Five moulds with allergenic compounds or mycotoxin production characteristics (Cladosporium sphaerospermum, Penicillium chrysogenum, Aspergillus versicolor, Alternaria alternata and Stachybotrys chartarum) were quantified using Rt-PCR. Cycle threshold results were expressed in spore equivalent per volume or surface unit using a direct calculation based on a spore standard curve. MDH presented significantly higher amounts of DNA from C. sphaerospermum in both air and surface samples than CH (P < 0.001). APH presented slightly elevated amounts of DNA from A. versicolor in both air and surface samples, compared to CH (P < 0.05). CONCLUSION: Rt-PCR quantification of targeted fungal species is a rapid, reliable tool that could be included in a global indoor mould evaluation. SIGNIFICANCE AND IMPACT OF THE STUDY: Quantification of C. sphaerospermum using Rt-PCR can help to better target social service intervention in MDH. Quantification of A. versicolor DNA could be informative for characterization of APH.


Asunto(s)
Microbiología Ambiental , Hongos/clasificación , Hongos/aislamiento & purificación , Reacción en Cadena de la Polimerasa/métodos , Recuento de Colonia Microbiana/métodos , Hongos/genética , Vivienda , Humanos
14.
HNO ; 57(8): 808-11, 2009 Aug.
Artículo en Alemán | MEDLINE | ID: mdl-19618128

RESUMEN

A 56-year-old female patient presented with a 3-day-old odynophagy and a painful swelling in the left side of the neck. In addition to reddening and swelling of the left side of the neck, which was painful on palpation, leukocytosis and increased C-reactive protein (CRP) and fibrinogen levels were also found. Enlarged lymph nodes along the left vessel-nerve sheath and thrombosis of the internal jugular vein were detected by sonography and computed tomography. The patient could be identified as a heterozygote carrier of the factor V Leiden mutation. This mutation has a thrombotic characteristic due to resistance to activated protein C (APC). Subacute lymphadenitis was an additional disruptive factor and led to thrombosis in the internal jugular vein. The patient received antibiotic treatment and Marcumar, which is planned to be given for a 3-month period.


Asunto(s)
Linfadenitis/complicaciones , Linfadenitis/diagnóstico , Dolor de Cuello/diagnóstico , Dolor de Cuello/etiología , Cuello , Femenino , Humanos , Persona de Mediana Edad
15.
HNO ; 57(9): 959-63, 2009 Sep.
Artículo en Alemán | MEDLINE | ID: mdl-19696974

RESUMEN

We report on a 48-year old female patient suffering from recurrent suppurative sialo-adenitis. Resections of both parotid and the left submandibular glands had to be performed due to abscesses. The woman had suffered from recurrent swelling of the salivary glands as well as xerostomia and xerophthalmia for years. Sjögren's syndrome was diagnosed with a delay of 17 years. The current case implicates recurrent bacterial suppurative sialo-adenitis caused by longstanding Sjögren's syndrome. In every case rheumatic disorders have to be considered in the differential diagnosis of recurrent suppurative parotitis. A detailed anamnesis, ultrasound, a differential hemogram, testing for rheumatoid factor and anti-nuclear antibodies (ANA) as well as SS-A and SS-B ENAs can give early information years before Sjögren's syndrome becomes clinically apparent.


Asunto(s)
Absceso/diagnóstico , Absceso/cirugía , Enfermedades de las Parótidas/diagnóstico , Enfermedades de las Parótidas/cirugía , Síndrome de Sjögren/diagnóstico , Síndrome de Sjögren/cirugía , Femenino , Humanos , Persona de Mediana Edad , Prevención Secundaria , Resultado del Tratamiento
16.
Clin Exp Immunol ; 154(1): 6-14, 2008 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-18761662

RESUMEN

From 19 to 21 May 2008 an important meeting was held at the Pasteur Institute in Paris to mark the 25th Anniversary of the discovery of HIV as the aetiological agent of AIDS. This review summarizes the historical findings, recent work and future directions presented at this meeting.


Asunto(s)
Infecciones por VIH/virología , VIH/patogenicidad , Vacunas contra el SIDA/uso terapéutico , Fármacos Anti-VIH/uso terapéutico , Terapia Antirretroviral Altamente Activa , Genes Virales , Predisposición Genética a la Enfermedad , VIH/genética , Infecciones por VIH/inmunología , Infecciones por VIH/prevención & control , Humanos
19.
Cancer Res ; 37(6): 1702-8, 1977 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-870184

RESUMEN

On the basis of the multi-hit concept of cancer formation, the relationships between tumor incidence and dose and time of administration of carcinogen have been analyzed. Simple mathematics have been used, since the available data, in our opinion, hardly justify more sophisticated formularization. The exponential relationship between the cumulative tumor incidence and the dose and time of administration of carcinogen can be described as l(d,t) approximately dmtr. With use of Druckrey's formula, dtn=k, it was derived that the exponent of time, r, is equal to m-n, in which m is the power of the dose dependency of tumor formation [l(d) approximately dm measured at a fixed time] and n is the autonomous time factor featured in the former formula. The factor m is interpretable in terms of the number of discrete events (hits) required for tumor formation, whereas the factor n is mainly determined by the rate of proliferation of intermediate cell populations participating in the carcinogenic process. Since r and n can be experimentally determined, the formula allows the calculation of the exponent (m) of the dose dependency of tumor formation. Analysis of malignant liver tumor formation in the rat by continuous administration of diethylnitrosamine yeilded m = 7, from which it was concluded that seven hits were instrumental in the induction of these liver-cell tumors. Analysis of the formation of less malignant liver tumors after one pulse exposure to the same carcinogen suggested that the process was initiated by at most two concomitant hits in a liver cell and brought to completion by three spontaneous events (changes). The view was advanced that tumor formation in general may result from hits inflicted by the carcinogen applied and from "background" hits (i.e., spontaneous changes and/or hits by carcinogenic stimuli from the environment or present endogenously) and that the relative contribution of these two types of hits to the end effect may depend on dose level and potency of the carcinogen under consideration. It was pointed out that the direct measurement of the dose-response relation (l(d) approximately dm) yields only the number of hits contributed by the carcinogen applied anose rate is low or very low, the contribution of background process becomes significant, and these hits contribute to the power of time, r, of the incidence-time relation. Under these conditions, the formula m-n=r becomes (mex + mb)n=r, where mex and mb denote the number of hits scored by extrinsic carcinogen and background processes, respectively. It is argued that the epidemiological data on lung cancer caused by smoking [l(d) approximately d with respect to smoke dose, mex= 1; l(t) approximately t5 with respect to duration of smoking] are not compatible unless at least one additional background hit (mb greater than or equal to 1) is postulated...


Asunto(s)
Neoplasias Hepáticas/inducido químicamente , Neoplasias Pulmonares/inducido químicamente , Animales , Carcinógenos/administración & dosificación , Transformación Celular Neoplásica , Dietilnitrosamina/administración & dosificación , Relación Dosis-Respuesta a Droga , Humanos , Cinética , Matemática , Neoplasias Experimentales/inducido químicamente , Fumar/complicaciones
20.
Cancer Res ; 36(7 PT 2): 2544-54, 1976 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-132270

RESUMEN

A single application of various hepatocarcinogens to rats results in the formation of islands of enzyme-deficient liver cells, which are mainly irreversible and very probably represent the first cellular stage involved in the process of liver cancer formation. Comparison of the island-size distributions obtained for different carcinogens indicated that proliferation is a common property of islands that is independent of the inducing carcinogen and does not need any further presence of carcinogen or other stimulating factors. Toxic doses resulted in all cases in an enhanced island size. The number of islands induced by a single dose of carcinogen was enhanced by a prior partial hepatectomy only in the case of the dialkylnitrosamines, dimethylnitrosamine, and diethylnitrosamine. Dose-response relationships measured with diethylnitrosamine, the carcinogen with the lowest toxicity as compared with the carcinogenic action, indicated that island formation is due to a one-hit process, i.e., that one specific alteration in the target cell is responsible for the precancerous transformation. These kinetics and the low probability of transformation might indicate that the crucial hit is scored at the genetic level. The irreversible action of carcinogen (memory effect) and the influence of time on cancer formation (time effect) are discussed in terms of induction and proliferation of irreversible cell populations serving as precursor of the cancer cell. The number of specific alterations (hits) involved in the development of the malignant cancer cell is also briefly discussed.


Asunto(s)
Adenosina Trifosfatasas/deficiencia , Neoplasias Hepáticas/enzimología , Lesiones Precancerosas/enzimología , Animales , Carcinógenos , ADN Nucleotidiltransferasas/fisiología , Dietilnitrosamina/administración & dosificación , Relación Dosis-Respuesta a Droga , Hiperplasia/enzimología , Cinética , Neoplasias Hepáticas/inducido químicamente , Neoplasias Hepáticas/etiología , Mutación , Neoplasias Experimentales , Fenotipo , Lesiones Precancerosas/inducido químicamente , Lesiones Precancerosas/patología , Ratas
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