RESUMO
Zymoseptoria tritici is the causal agent of Septoria tritici blotch (STB), a disease of wheat (Triticum aestivum) that results in significant yield loss worldwide. Z. tritici's life cycle, reproductive system, effective population size, and gene flow put it at high likelihood of developing fungicide resistance. Succinate dehydrogenase inhibitor (SDHI) fungicides (FRAC code 7) were not widely used to control STB in the Willamette Valley until 2016. Field isolates of Z. tritici collected in the Willamette Valley at dates spanning the introduction of SDHI (2015 to 2017) were screened for sensitivity to four SDHI active ingredients: benzovindiflupyr, penthiopyrad, fluxapyroxad, and fluindapyr. Fungicide sensitivity changes were determined by the fungicide concentration at which fungal growth is decreased by 50% (EC50) values. The benzovindiflupyr EC50 values increased significantly, indicating a reduction in sensitivity, following the adoption of SDHI fungicides in Oregon (P < 0.0001). Additionally, significant reduction in cross-sensitivity among SDHI active ingredients was also observed with a moderate and significant relationship between penthiopyrad and benzovindiflupyr (P = 0.0002) and a weak relationship between penthiopyrad and fluxapyroxad (P = 0.0482). No change in cross-sensitivity was observed with fluindapyr, which has not yet been labeled in the region. The results document a decrease in SDHI sensitivity in Z. tritici isolates following the introduction of the active ingredients to the Willamette Valley. The reduction in cross-sensitivity observed between SDHI active ingredients highlights the notion that careful consideration is required to manage fungicide resistance and suggests that within-group rotation is insufficient for resistance management.
Assuntos
Fungicidas Industriais , Ascomicetos , Farmacorresistência Fúngica , Fungicidas Industriais/farmacologia , Norbornanos , Oregon , Doenças das Plantas , Pirazóis , Succinato Desidrogenase/genética , Ácido SuccínicoRESUMO
PURPOSE: To compare the accuracy of MR enterography (MRE) using combined T2-weighted and contrast-enhanced (CE) sequences with that of combined T2- and diffusion-weighted (DW) sequences for the detection of complex enteric Crohn's disease (CD). MATERIALS: Thirty-eight patients who underwent surgery for CD complications and preoperative MRE from 2011 to 2016 were included. MRE examinations were blindly analyzed independently by one junior and one senior abdominal radiologist for the presence of fistula, stenosis and abscesses. During a first reading session, T2-weighted images (WI), steady-state sequences and DW-MRE were reviewed (set 1). During a separate distant session, T2-WI, True-FISP and CE-MRE were reviewed (set 2). Performance of each reader was evaluated by comparison with the standard of reference established using intraoperative and pathological findings. RESULTS: Forty-eight fistulas, 43 stenoses and 11 abscesses were found. For the senior radiologist, sensitivity for the detection of fistula, stenosis and abscess ranged from 80% to 100% for set 1 and 88% to 100% for set 2 and specificity ranged from 56% to 70% for set 1 and 53% to 93% for set 2, with no significant difference between the sets (p = 0.342-0.429). For the junior radiologist, sensitivity ranged from 53% to 63% for set 1 and 64% to 88% for set 2 and specificity ranged from 0% to 25% for set 1 and 17% to 40% for set 2 (p = 0.001 and 0.007, respectively). CONCLUSION: For a senior radiologist, DW-MRE has similar sensitivity as CE-MRE for the detection of CD complications. For a junior radiologist, CE-MRE yields the best results compared with DW-MRE. KEY POINTS: ⢠For experienced readers, DWI has similar diagnostic capability as contrast-enhanced MR imaging for the diagnosis of Crohn's disease complications. ⢠For senior radiologists, gadolinium chelate injection could be waived for the diagnosis of Crohn's disease complications. ⢠The interpretation of DWI for Crohn's disease complications requires some experience.
Assuntos
Meios de Contraste/farmacologia , Doença de Crohn/diagnóstico por imagem , Aumento da Imagem/métodos , Intestino Delgado/diagnóstico por imagem , Imageamento por Ressonância Magnética/métodos , Complicações Pós-Operatórias/diagnóstico , Cuidados Pré-Operatórios/métodos , Adolescente , Adulto , Doença de Crohn/cirurgia , Imagem de Difusão por Ressonância Magnética/métodos , Procedimentos Cirúrgicos do Sistema Digestório/efeitos adversos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adulto JovemRESUMO
OBJECTIVES: Allergic fungal rhinosinusitis (AFRS) and eosinophilic mucin chronic rhinosinusitis (EMRS) are two forms of chronic sinusitis distinguished by the presence (AFRS) or absence (EMRS) of fungal elements in sinus mucin. Detection of the fungal elements, however, is complex and it is difficult to say whether EMRS is in fact an entity distinct from AFRS. The aim of the present study, based on a retrospective series of AFRS and EMRS, was to identify the specific clinical and radiological elements distinguishing between the two. MATERIALS AND METHODS: A 2-center retrospective observational study following STROBE guidelines included patients managed for AFRS or EMRS between 2009 and 2022. Clinical, mycological, pathologic and radiological data were collected. Type of treatment and disease progression were also analyzed. Intergroup comparison used Student's test for mean values of quantitative variables, with calculation of P-values, and Pearson's Chi2 test or Fisher's exact test for categoric variables, with calculation of relative risk and 95% confidence intervals. RESULTS: The AFRS group comprised 41 patients and the EMRS group 34. Demographic data were comparable between groups. EMRS showed a higher rate of asthma (79.4 vs. 31.4%; P<0.001), more severe nasal symptomatology (rhinorrhea, P=0.01; nasal obstruction, P=0.001), and more frequent bilateral involvement (85.3 vs. 58.5%; P=0.021). AFRS showed more frequent complications (19 vs. 0%; P=0.006). Radiologically, mucin accumulation was greater in AFRS, filling the sinus in 84.2% of cases, versus 26.3% (P<0.001), with more frequent sinus wall erosion (19 vs. 5.8%; P=0.073). The recurrence rate was higher in EMRS: 38.2 vs.21.9% (P=0.087). CONCLUSION: The present retrospective study found a difference in clinical and radiological presentation between AFRS and EMRS, with EMRS more resembling the presentation of severe nasal polyposis.
Assuntos
Sinusite Fúngica Alérgica , Micoses , Sinusite , Humanos , Doença Crônica , Mucinas , Micoses/complicações , Micoses/diagnóstico , Micoses/microbiologia , Estudos Retrospectivos , Sinusite/complicações , Sinusite/diagnósticoRESUMO
Distinctive hyaline inclusion bodies in the cytoplasm of neocortical astrocytes were observed in surgical resection specimens of a frontal epileptic focus, in 2 patients aged 16 and 10 who had suffered intractable partial seizures since the age of 2 years. One case had minimal neurological impairment and no brain malformation on MRI and recovered completely following surgery. The second case had mental retardation and surgery reduced the frequency and generalization of seizures. In both cases, the astrocytic inclusions were strongly eosinophilic, hyaline and refractile. They were PAS negative. Electron microscopy in the first case, confirmed their granular osmiophilic structure. By immunohistochemistry, the inclusions were strongly positive for filamin in the first case, only some were weakly positive in the second case. They also variably expressed other proteins such as alpha-B-crystallin, GFAP, S-100 protein and cytoglobin. We compare our findings with previously reported cases and discuss the clinical significance of the inclusions and the pathophysiologic relevance of filamin A and other proteins accumulation in astrocytes.
Assuntos
Astrócitos , Epilepsia do Lobo Frontal/patologia , Hialina , Corpos de Inclusão/patologia , Adolescente , Criança , Proteínas Contráteis , Epilepsia do Lobo Frontal/metabolismo , Epilepsia do Lobo Frontal/cirurgia , Feminino , Filaminas , Humanos , Corpos de Inclusão/metabolismo , Proteínas dos MicrofilamentosRESUMO
Chronic idiopathic granulomatous arteritis of the large vessels - and, specifically, "Takayasu's arteritis" and "giant cell arteritis" - is an unusual condition that rarely leads to stroke and is only occasionally associated with Crohn's disease. We report here on a unique case of a 56-year-old man with a 25-year history of Crohn's disease who also had a 4-year history of recurrent right-sided ischaemic strokes and partial seizures, and a unilateral progressive retrograde occlusion of the right internal and common carotid arteries. Biopsies of the temporal and carotid arteries showed large-vessel granulomatous arteritis, with features of both giant cell and Takayasu's arteritis.
Assuntos
Doenças das Artérias Carótidas/patologia , Doença de Crohn/patologia , Vasculite do Sistema Nervoso Central/patologia , Doenças das Artérias Carótidas/complicações , Angiografia Cerebral , Doença de Crohn/complicações , Lateralidade Funcional/fisiologia , Humanos , Imuno-Histoquímica , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Transtornos dos Movimentos/etiologia , Recidiva , Acidente Vascular Cerebral/complicações , Acidente Vascular Cerebral/patologia , Vasculite do Sistema Nervoso Central/complicaçõesRESUMO
There is no standard treatment in patients with high risk metachronous peritoneal carcinomatosis (PC) in colonic cancer, as perforated tumour or synchronous ovarian metastasis. Icodextrin 4% (ICDX), presently used to prevent postoperative abdominal adhesions, could inhibit the coactivation of the tumour cells and the microenvironment cells, associated with the development of PC. The aim of this study was to inhibit the formation of the PC in a murine model mimicking surgical situation using ICDX and intraperitoneal (IP) prophylactic chemotherapy. We created a model of growing PC in mice using cells of murine colonic cancer CT26. Cells and treatments were injected simultaneously. Five groups were created: CT26 (control group), CT26 + ICDX (ICDX group), CT26 + chemotherapy (oxaliplatin and 5FU) (chemo group), CT26 + chemotherapy + ICDX (ICDX chemo group), ICDX (toxicity group). At day 15, PC was evaluated with rodents PCI. In the chemo group, PCI was significantly lower than in the control group (3.2 versus 8.4, p = 0.02). ICDX had a synergetic effect on PC with chemotherapy; indeed PCI in ICDX chemo group was lower than in chemo group (1.4 versus 3.2, p = 0.04). There was no morbidity linked to ICDX in toxicity group. Safety of ICDX needs to be verified, particularly on colonic anastomosis before ICDX associated to IP chemotherapy could be used as a preventive treatment of PC in high risk patients. This prophylactic treatment is easy to use and would be administrated at the end of a curative surgery for a colonic cancer.
Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/farmacologia , Carcinoma/tratamento farmacológico , Neoplasias do Colo/tratamento farmacológico , Soluções para Diálise/farmacologia , Glucanos/farmacologia , Glucose/farmacologia , Neoplasias Peritoneais/tratamento farmacológico , Animais , Protocolos de Quimioterapia Combinada Antineoplásica/administração & dosagem , Carcinoma/secundário , Linhagem Celular Tumoral , Movimento Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Neoplasias do Colo/patologia , Soluções para Diálise/uso terapêutico , Modelos Animais de Doenças , Fluoruracila/administração & dosagem , Fluoruracila/farmacologia , Glucanos/uso terapêutico , Glucose/uso terapêutico , Icodextrina , Infusões Parenterais , Camundongos , Compostos Organoplatínicos/administração & dosagem , Compostos Organoplatínicos/farmacologia , Oxaliplatina , Neoplasias Peritoneais/secundárioRESUMO
BACKGROUND: Pseudomyxoma peritonei (PMP) is a rare carcinomatosis limited to the peritoneal cavity, mainly supplied by the superior mesenteric artery (SMA). The only curative treatment is cytoreductive surgery (CRS) associated with hyperthermic intraperitoneal chemotherapy. This study aimed to evaluate the ability of blood flow volume (BFV) recorded in the SMA using Doppler ultrasonography pre-operatively to predict the extent and resectability of the disease and post-operatively to assess clinical outcome. METHODS: BFV was measured in the SMA of forty-nine patients before and the year following CRS. Patients were categorized in 3 groups according to clinical and surgical outcomes: group-1 (n = 22): patient with completed CRS, group-2 (n = 16): incomplete resection with slowly progressive disease (alive at 2 years without severe clinical symptoms), group-3 (n = 11): incomplete resection and with severe clinical symptoms or dead within two years. RESULTS: Pre-operative mean SMA BFV was higher in group-2 (510 mL/min, p = 0.027) and in group-3 (572 mL/min, p = 0.004) than in group-1 (378 mL/min). After surgery, BFV dropped to normal values (203 mL/min, p = 0.001) in group-1, and to 423 mL/min (p = 0.047) in group-2. It remained elevated in group-3 (626 mL/min, p = 0.566). BFV allowed stratification of 1) resectability before CRS (group-2 and -3 vs group-1, area under the ROC curve: 0.794 [0.650-0.939]), and 2) non progression after incomplete CRS (group-3 vs group-2, area under the ROC curve: 0.827 [0.565-1.00]. CONCLUSIONS: Pre-operative BFV in the SMA correlates with extent and resectability of PMP. After incomplete surgery, post-operative BFV might aid in identifying patients who may benefit of post-operative therapy.
Assuntos
Procedimentos Cirúrgicos de Citorredução/métodos , Artéria Mesentérica Superior/fisiopatologia , Neoplasias Peritoneais/cirurgia , Pseudomixoma Peritoneal/cirurgia , Fluxo Sanguíneo Regional/fisiologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Seguimentos , França/epidemiologia , Humanos , Masculino , Artéria Mesentérica Superior/diagnóstico por imagem , Pessoa de Meia-Idade , Neoplasias Peritoneais/diagnóstico , Neoplasias Peritoneais/mortalidade , Valor Preditivo dos Testes , Pseudomixoma Peritoneal/diagnóstico , Pseudomixoma Peritoneal/mortalidade , Estudos Retrospectivos , Taxa de Sobrevida/tendências , Fatores de Tempo , Resultado do Tratamento , Ultrassonografia Doppler/métodosRESUMO
BACKGROUND: Patients treated with chemotherapy for microsatellite unstable (MSI) and/or mismatch repair deficient (dMMR) cancer metastatic colorectal cancer (mCRC) exhibit poor prognosis. We aimed to evaluate the relevance of distinguishing sporadic from Lynch syndrome (LS)-like mCRCs. PATIENTS AND METHODS: MSI/dMMR mCRC patients were retrospectively identified in six French hospitals. Tumour samples were screened for MSI, dMMR, RAS/RAF mutations and MLH1 methylation. Sporadic cases were molecularly defined as those displaying MLH1/PMS2 loss of expression with BRAFV600E and/or MLH1 hypermethylation and no MMR germline mutation. RESULTS: Among 129 MSI/dMMR mCRC patients, 81 (63%) were LS-like and 48 (37%) had sporadic tumours; 22% of MLH1/PMS2-negative mCRCs would have been misclassified using an algorithm based on local medical records (age, Amsterdam II criteria, BRAF and MMR statuses when locally tested), compared to a systematical assessment of MMR, BRAF and MLH1 methylation statuses. In univariate analysis, parameters associated with better overall survival were age (P < 0.0001), metastatic resection (P = 0.001) and LS-like mCRC (P = 0.01), but not BRAFV600E. In multivariate analysis, age (hazard ratio (HR) = 3.19, P = 0.01) and metastatic resection (HR = 4.2, P = 0.001) were associated with overall survival, but not LS. LS-like patients were associated with more frequent liver involvement, metastatic resection and better disease-free survival after metastasectomy (HR = 0.28, P = 0.01). Median progression-free survival of first-line chemotherapy was similar between the two groups (4.2 and 4.2 months; P = 0.44). CONCLUSIONS: LS-like and sporadic MSI/dMMR mCRCs display distinct natural histories. MMR, BRAF mutation and MLH1 methylation testing should be mandatory to differentiate LS-like and sporadic MSI/dMMR mCRC, to determine in particular whether immune checkpoint inhibitors efficacy differs in these two populations.
Assuntos
Biomarcadores Tumorais/genética , Neoplasias Colorretais Hereditárias sem Polipose/genética , Neoplasias Colorretais/genética , Metilação de DNA , Reparo de Erro de Pareamento de DNA , Instabilidade de Microssatélites , Proteína 1 Homóloga a MutL/genética , Mutação , Proteínas Proto-Oncogênicas B-raf/genética , Adulto , Idoso , Neoplasias Colorretais/mortalidade , Neoplasias Colorretais/patologia , Neoplasias Colorretais/terapia , Neoplasias Colorretais Hereditárias sem Polipose/mortalidade , Neoplasias Colorretais Hereditárias sem Polipose/patologia , Neoplasias Colorretais Hereditárias sem Polipose/terapia , Diagnóstico Diferencial , Intervalo Livre de Doença , Feminino , França , Predisposição Genética para Doença , Hereditariedade , Humanos , Estimativa de Kaplan-Meier , Masculino , Pessoa de Meia-Idade , Técnicas de Diagnóstico Molecular , Análise Multivariada , Metástase Neoplásica , Linhagem , Fenótipo , Valor Preditivo dos Testes , Modelos de Riscos Proporcionais , Estudos Retrospectivos , Fatores de Risco , Fatores de Tempo , Resultado do TratamentoRESUMO
The Abraham solvation parameter model is used to construct mathematical correlations for describing the nonspecific toxicity of organic compounds to three protozoas (Entosiphon sulcantum, Uronema parduczi and Chilomonas paramecium). The derived mathematical correlations describe the observed published toxicity data to within an overall average standard deviation of approximately 0.35 log units. The correlations can be used to estimate aquatic toxicities of organic chemicals to the three aquatic organisms studied, and to help in identifying compounds whose toxic mode of action might involve chemical specific reactivity, rather than nonpolar or polar narcosis. A principal component analysis of the correlation equations found in this work shows that no water-solvent system we have investigated is a good model for nonspecific aquatic toxicity towards the three protozoas. Furthermore, correlation equations for nonspecific aqueous toxicity towards various biological systems, that we have found in this work and in previous studies, cover such a wide range that no single water-solvent system could ever be a good model for all the biological systems.
Assuntos
Cilióforos/efeitos dos fármacos , Criptófitas/efeitos dos fármacos , Euglênidos/efeitos dos fármacos , Compostos Orgânicos/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Cilióforos/crescimento & desenvolvimento , Criptófitas/crescimento & desenvolvimento , Euglênidos/crescimento & desenvolvimento , Modelos Biológicos , Análise de Componente PrincipalRESUMO
The narcotic and lethal concentrations of organic compounds have been compiled for several tadpole species (Rana temporaria, Rana pipiens, Rana japonica, Xenopus laevis and Rana brevipoda porosa). The narcotic and lethal concentrations have been correlated using the Abraham solvation parameter model to yield an equation that can be used to predict the narcotic concentrations of additional nonpolar and polar narcotic compounds to R. temporaria, and a more general correlation that should be applicable to different species of tadpoles. The more general equation is based on 240 experimental data points. A training set of 123 compounds could be fitted with the Abraham solvation parameters with R(2)=0.931 and S.D.=0.343 log units. The training equation predicted the test set of 122 values with AE=-0.022 log units, S.D.=0.300 log units and an average absolute error, AAE, of 0.227 log units. The structural features that are important in narcosis of tadpoles have been examined; it is concluded that hydrogen bond basicity reduces narcotic activity of compounds and that compound size increases narcotic activity. The solvation parameter model enables narcosis of tadpoles to be compared to various other biological processes and to physicochemical processes that might be used as models for narcosis.
Assuntos
Anuros/crescimento & desenvolvimento , Modelos Biológicos , Compostos Orgânicos/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Larva/efeitos dos fármacos , Larva/crescimento & desenvolvimento , Compostos Orgânicos/química , SoluçõesRESUMO
Radiation-induced sarcoma is a long-term complication of radiation therapy. The most common secondary neoplasia is the undifferentiated pleomorphic sarcoma, which is usually described in the deep soft tissue of the trunk or extremities. Radiation-induced sarcomas have a poor prognosis. An early diagnosis and management are needed to improve the survival rate of such patients. We presently report a case of a radiation-induced undifferentiated pleomorphic sarcoma of the left gluteus maximus muscle, which developed 25 years after an initial diagnosis of aggressive fibromatosis and 21 years after a tumour recurrence. This case study illustrates the risk of developing a sarcoma in a radiation field and the need for long-term follow-up after radiation therapy. Unnecessary radiation therapy, in particular in the case of benign conditions in young patients, should be avoided.
Assuntos
Neoplasias Musculares/patologia , Neoplasias Induzidas por Radiação/patologia , Sarcoma/patologia , Nádegas , Feminino , Fibromatose Agressiva/radioterapia , Humanos , Pessoa de Meia-Idade , Recidiva Local de Neoplasia/radioterapia , Neoplasias de Tecidos Moles/radioterapiaAssuntos
Fissura Anal/patologia , Granuloma de Células Gigantes/patologia , Doença Granulomatosa Crônica/patologia , Doenças Inflamatórias Intestinais/patologia , Colonoscopia , Diagnóstico Diferencial , Fissura Anal/etiologia , Doença Granulomatosa Crônica/complicações , Humanos , Masculino , Adulto JovemRESUMO
The ambulant recording of the electrocardiogram by the Holter technique has become one of the non invasive examinations widely used in two indications: paroxysmal arrhythmias and coronary disease. However, the technical limitations of the method and the occasionally improper extension of the indications of Holter recording lead to disappointing results. The aim of this work is an estimation of the usefulness of Holter as a function of the desired information by a statistical study. Of 646 consecutive recordings, 200 were taken at random; 169 usable ones were classed in 7 categories according to the clinical requirement; the overall usefulness amounts to 27.5 percent of the cases in which Holter permits a diagnosis. As far as paroxysmal disturbances of rhythm are concerned, Holter is more efficacious than the standard electrocardiogram. However, the efficiency of the method is low: 17.4 percent of cases when it was required to find a cardiac arrhythmia causing a cerebral vascular accident, and even lower, 5.1 percent, when a malaise was concerned. In 20 percent of the cases was a useful tool in diagnosing thoracic pain. In 9.5 percent of the cases the tracings were not interpretable owing to their poor quality. These findings urge more rigor in the choice of indications and a better control of technical problems if the efficacy of the method is to be improved.
Assuntos
Eletrocardiografia/métodos , Cardiopatias/diagnóstico , Monitorização Fisiológica , Idoso , Assistência Ambulatorial , Arritmias Cardíacas/fisiopatologia , Doença das Coronárias/fisiopatologia , Estudos de Avaliação como Assunto , Feminino , Coração/fisiopatologia , Humanos , Masculino , Pessoa de Meia-Idade , Estatística como Assunto , Síncope/fisiopatologiaRESUMO
Transjugular liver biopsy is a safe, effective and well-tolerated technique to obtain liver tissue specimens in patients with diffuse liver disease associated with severe coagulopathies or massive ascites. Transjugular liver biopsy is almost always feasible. The use of ultrasonographic guidance for percutaneous puncture of the right internal jugular vein is recommended to decrease the incidence of local cervical minor complications. Semiautomated biopsy devices are very effective in obtaining optimal tissue samples for a precise and definite histological diagnosis with a very low rate of complication. The relative limitations of transjugular liver biopsy are the cost, the radiation dose given to the patient, the increased procedure time by comparison with the more common percutaneous liver biopsy, and the need of a well-trained interventional radiologist.
Assuntos
Biópsia por Agulha/métodos , Fluoroscopia/métodos , Veias Jugulares , Hepatopatias/patologia , Fígado/patologia , Ultrassonografia de Intervenção/métodos , Biópsia por Agulha/efeitos adversos , Biópsia por Agulha/instrumentação , Desenho de Equipamento , Fluoroscopia/efeitos adversos , Fluoroscopia/instrumentação , Humanos , Ultrassonografia de Intervenção/efeitos adversos , Ultrassonografia de Intervenção/instrumentaçãoAssuntos
Neoplasias da Vesícula Biliar/diagnóstico , Imagem Multimodal , Tumores Neuroendócrinos/diagnóstico , Feminino , Neoplasias da Vesícula Biliar/diagnóstico por imagem , Neoplasias da Vesícula Biliar/patologia , Humanos , Masculino , Pessoa de Meia-Idade , Tomografia Computadorizada Multidetectores , Tumores Neuroendócrinos/diagnóstico por imagem , Tumores Neuroendócrinos/patologia , UltrassonografiaRESUMO
The Abraham solvation parameter model is used to construct mathematical correlations for describing the nonspecific aquatic toxicity of organic compounds to the fathead minnow, guppy, bluegill, goldfish, golden orfe, and high-eyes medaka. The derived mathematical correlations describe the observed published toxicity data to within an overall average standard deviation of approximately 0.28 log units. In the case of ester solutes, the descriptions were improved by introducing an indicator variable into the basic model. Derived correlations can be used to estimate aquatic toxicities of organic chemicals to the six fish species studied and to help in identifying compounds whose toxic mode of action might involve chemical specific reactivity, rather than nonpolar or polar narcosis. A principal component analysis of the correlation equations shows that the water-octanol system is a poor model for nonspecific aquatic toxicity but that the water-isobutanol and water-pentanol systems are much better models.