Assuntos
Agonistas do Receptor A2 de Adenosina/farmacologia , Purinas/farmacologia , Pirazóis/farmacologia , Sistema Nervoso Simpático/efeitos dos fármacos , Idoso , Pressão Sanguínea , Eletrocardiografia , Teste de Esforço , Frequência Cardíaca/efeitos dos fármacos , Hemodinâmica/efeitos dos fármacos , Humanos , Masculino , Imagem de Perfusão do Miocárdio , Receptor A2A de Adenosina/metabolismo , Tomografia Computadorizada de Emissão de Fóton ÚnicoRESUMO
INTRODUCTION: Noxafil® (posaconazole; POS) is a potent, selective triazole antifungal approved for use in adults as an oral suspension, oral tablet and intravenous (IV) Solution. In support of pediatric administration of POS IV Solution to children
Assuntos
Envelhecimento/patologia , Antifúngicos/toxicidade , Ventrículos Cerebrais/efeitos dos fármacos , Imageamento por Ressonância Magnética , Triazóis/toxicidade , Animais , Antifúngicos/administração & dosagem , Ventrículos Cerebrais/patologia , Cães , Feminino , Injeções Intravenosas , Masculino , Soluções , Triazóis/administração & dosagemRESUMO
We report an extremely rare case of extrarenal testicular Wilms' tumor in a 3-year-old boy with intrabdominal undescended left testis. The patient was admitted because of pain and vomiting, with evidence of a huge abdominal mass. At surgery a large tumor arising from the intrabdominal testis was found. Histology showed the classical triphasic Wilms' tumor elements: epithelial, mesenchymal and blastemal areas. Extrarenal Wilms' tumors account for only 3% of all Wilms' tumors and just -100 cases have been reported in literature. Testicular origin is anecdotic. We present histomorphological, histogenetic, clinical, diagnostic, prognostic and therapeutic features of this rare tumor.
Assuntos
Neoplasias Testiculares/cirurgia , Tumor de Wilms/cirurgia , Pré-Escolar , Meios de Contraste , Seguimentos , Humanos , Masculino , Intensificação de Imagem Radiográfica/métodos , Neoplasias Testiculares/diagnóstico por imagem , Tomografia Computadorizada por Raios X/métodos , Ultrassonografia Doppler/métodos , Tumor de Wilms/diagnóstico por imagemRESUMO
Scrotal swelling suggesting testicular torsion is a rare urological emergency which requires a clinical urgent evaluation and most of the times must be managed surgically. In newborns it can occur in the postnatal period, usually within the twenty-eighth day of life, or more frequently in utero, during the descent of the testis into the scrotum. Usually its poor fixedness allows the testis an abnormal mobility inside the scrotum, configuring the framework of extravaginal torsion. On the contrary during the perinatal period a twist that takes place inside the tunica vaginalis, known as intravaginal torsion, is extremely uncommon and only few cases are well documented in the literature. Authors present a rare case of intravaginal testicular torsion occurred in perinatal period. In this situation only the early surgical exploration of the scrotum may allow the rescue of the gonad, although in rare cases. Timing of surgical treatment and need for contralateral testicular fixation remain controversial. However since the anatomical defect of the tunica vaginalis can be bilateral the surgical fixation even of the contralateral testis is important, now or later, in order to prevent any future torsion of this gonad. The authors also present a brief review of recent literature on the subject.
Assuntos
Torção do Cordão Espermático/cirurgia , Testículo/cirurgia , Humanos , Recém-Nascido , Masculino , Torção do Cordão Espermático/congênito , Testículo/patologia , Fatores de TempoRESUMO
Thoracic tumours of childhood arise either in the mediastinum, or from the chest wall and rarely from the lung parenchyma. Mediastinal teratoma occur in the anterior mediastinum and are usually very large at presentation; initial treatment is under discussion, but it appears that surgical excision and histological examination are the treatments of choice and it will determine whether the lesion is benign or malignant. The authors report a case of thoracic-abdominal teratoma, diagnosed in utero, and treated successfully with thoracoscopy and laparoscopy. No complication was described in short follow up, and the child was discharged in day 8th postoperative day. Histology showed mature teratoma. Follow-up at one year: no evidence of recurrence. Due to the rarity of multifocal teratoma in newborns, author believe that mini-invasive technique was useful to stage histological the mass, giving the opportunity to plans a second stage in treatment of the patient. Day of hospitalization resulted shorter in both surgical approaches, and discomfort less for the thoracic approach. This staging must be anyway planned, in the way of prenatal counselling and in the perinatal period, with the team involved in the procedure, that include anaesthetists, oncology staff, obstetricians, neonatologists and pediatric surgeons. It is mandatory in cases like the one reported that a multisciplinary team manage the patients and expert surgeons, especially in minimal invasive surgery, make the adequate plans.
Assuntos
Neoplasias Abdominais/cirurgia , Neoplasias do Mediastino/cirurgia , Neoplasias Primárias Múltiplas/cirurgia , Teratoma/cirurgia , Neoplasias Abdominais/diagnóstico , Feminino , Seguimentos , Humanos , Recém-Nascido , Laparoscopia , Masculino , Neoplasias do Mediastino/diagnóstico , Estadiamento de Neoplasias , Neoplasias Primárias Múltiplas/diagnóstico , Gravidez , Reoperação , Teratoma/diagnóstico , Toracoscopia , Resultado do Tratamento , Ultrassonografia Pré-NatalRESUMO
Neck masses are rare in newborns and can represent a big challenge for the paediatric surgeons. Different histological types are reported in the recent literature; while 80% of neck masses are benign, the pediatric surgeon is often called upon to assist in the evaluation, diagnosis and treatment. A two-month old baby was evaluated for an asymptomatic left sided cervical mass, presented at birth, which slowly increased in size. A magnetic resonance imaging scan was performed, with evidence of capsulated solid neck mass, lateral to the sternocleidomastoid muscle, not including the major vassel structures of the neck. The patient underwent surgical excision in the criteria to define the histology of the mass. A well capsulated mass was detected at surgery. At histology, an ectopic cervical thymus tissue was reported. The ectopic cervical thymus is an uncommon entity with only 91 cases reported; only nine occurred in infants, two in the neonatal period. According to the authors, in case of enlarging solid neck mass with unclear imaging or clinical data, complete surgical resection is the only and safe procedure to perform.
Assuntos
Coristoma , Pescoço , Timo , Coristoma/diagnóstico , Humanos , Lactente , MasculinoRESUMO
AIM: To verify a possible correlation between cell lipid composition, expression of key genes in lipid metabolism and fermentative behaviour of Saccharomyces cerevisiae wine strains. METHODS AND RESULTS: The fermentative abilities of two commercial wine strains of S. cerevisiae were tested under stressful conditions. Cell number, glucose and fructose concentrations, expression of ACS1, ACS2, ACC1, OLE1, ERG9, ERG10, ARE1 and ARE2 and lipid content were evaluated. The strain that failed to complete the fermentation had lower amounts of C16:1 and C16:0 fatty acids at the beginning of fermentation (0 h) and late logarithmic phase (72 h). While the amount of C18:1 in this strain was lower than that in the strain that completed the fermentation at 0 h, same levels were observed for both strains at 72 h. The sterol levels were generally higher in the strain that failed to complete the fermentation. Gene expression generally increased from the beginning of the fermentation to the late logarithmic phase in both strains. CONCLUSION: A positive correlation between good fermentative ability, elevated fatty acid content and ACC1 gene expression has been identified. SIGNIFICANCE AND IMPACT OF THE STUDY: The cell lipid content at the time of inoculum and expression of ACC1 gene of starter strains should be carefully considered in order to identify the possible stuck/sluggish fermentations.
Assuntos
Microbiologia Industrial , Lipídeos/análise , Saccharomyces cerevisiae/metabolismo , Vinho , DNA Fúngico/análise , Ácidos Graxos/biossíntese , Fermentação , Expressão Gênica , Regulação Fúngica da Expressão Gênica , Saccharomyces cerevisiae/química , Saccharomyces cerevisiae/genéticaRESUMO
PER.C6, a cell line derived from human embryonic retinal cells transformed with the Adenovirus Type 5 (Ad5) E1A and E1B genes, is used to produce E1-deleted Ad5 vectors such as the MRKAd5 HIV-1 gag vaccine. While whole, live PER.C6 cells are capable of growing as tumours when transplanted subcutaneously into immunodeficient nude mice at a high dosage, the process for vaccine production includes filtration steps and other methods which effectively preclude contamination by intact viable substrate cells. However, because of the neoplastic nature of this cell line, we carried out a series of investigations to assess the tumorigenic risk posed by residuals from the cell substrate in a vaccine. To address concerns about transmission of oncogenic DNA, we demonstrated that purified PER.C6 cellular DNA does not induce tumours in newborn hamsters or nude mice. To address concerns about other potential residuals, including hypothetical adventitious tumour viruses, we demonstrated that a PER.C6 cell lysate and a MRKAd5 HIV-1 gag vaccine produced on PER.C6 cells do not induce tumours in newborn hamsters or newborn rats. These results, in conjunction with the wide panel of viral safety tests performed on these cells, support the safety of the PER.C6 as a cell substrate for vaccine production.
Assuntos
Vacinas contra a AIDS/biossíntese , Adenovírus Humanos/genética , Vacinas contra a AIDS/normas , Animais , Animais Recém-Nascidos , Sequência de Bases , Testes de Carcinogenicidade , Linhagem Celular Transformada , Cricetinae , Primers do DNA , Vetores Genéticos , Células HeLa , Humanos , Camundongos , Camundongos Nus , Neoplasias/epidemiologia , Neoplasias/etiologia , Reação em Cadeia da Polimerase , Ratos , Retina/virologiaRESUMO
Sardinian sherry strains of S. cerevisiae form a biofilm on the surface of wine at the end of the ethanolic fermentation, when grape sugar is depleted and when further growth becomes dependent on access to oxygen. A point mutation in HSP12 or deletion of the entire gene results in inability to form this film. HSP12 encodes a heat-shock protein previously foundby others to be active during stationary phase, in cells depleted for glucose, and in cells metabolizing ethanol and fatty acids, all conditions associated with sherry biofilms.
Assuntos
Biofilmes/crescimento & desenvolvimento , Proteínas de Choque Térmico/genética , Saccharomyces cerevisiae/genética , Alelos , Sequência de Bases , Elementos de DNA Transponíveis , DNA Fúngico/genética , Proteínas de Choque Térmico/metabolismo , Dados de Sequência Molecular , Mutagênese , Reação em Cadeia da Polimerase , Saccharomyces cerevisiae/crescimento & desenvolvimento , Proteínas de Saccharomyces cerevisiae , Homologia de Sequência do Ácido Nucleico , VinhoRESUMO
Chronic beryllium disease (CBD) appears to arise from a combination of both exposure and genetic risk factors. A distinguishing feature of CBD is beryllium hypersensitivity, which can be measured in vitro by a lymphocyte proliferation test. The objective of this study was to determine whether certain allelic variations of the HLA-DPB1 gene, which had been observed previously in CBD, could be found in a group of individuals having beryllium hypersensitivity, but no symptoms of CBD. A flow cytometry-based Lymphocyte Proliferation Test combined with immunophenotyping (Immuno-LPT) was used to detect CD4+ and CD8+ T cell proliferation in response to in vitro stimulation with beryllium. The HLA-DPB1 haplotypes of the same individuals were determined by automated DNA sequencing. Twenty-two out of 25 beryllium-sensitive, non-CBD individuals were found to be carriers of the HLA-DPB1 gene having a substitution of a glutamic acid at position 69 in Exon 2 (Glu69), and a significantly high percentage (24%) were Glu69 homozygotes. Most of the CD4+ responders on the Immuno-LPT (10/14) carried rare, non-*0201 Glu69 DPB1 alleles; while most of the non-CD4+ responders (9/11) were common Glu69 carriers (*0201 or *0202) or non-Glu69 individuals (non-Glu69/non-Glu69). This is the first direct evidence that HLA-DP genotype is linked to a phenotypic response that occurs in beryllium sensitization in the absence of clinical CBD.
Assuntos
Beriliose/genética , Antígenos HLA-DP/genética , Divisão Celular/efeitos dos fármacos , Doença Crônica , DNA/química , DNA/genética , Genótipo , Humanos , Linfócitos/efeitos dos fármacos , Fenótipo , Valor Preditivo dos Testes , Subpopulações de Linfócitos TRESUMO
The behaviour of the fungicide, fenhexamid, on grapes, and during wine-making, as well as its effect on the microflora of alcoholic and malolactic fermentation has been studied. After treatment, the residue on grapes decreased rapidly to one-third of the initial level after the first week, while it remained constant during the following two weeks. At harvest, in the wine obtained by vinification without skins, the fungicide residue decreased on average by 49%, while in the wine obtained by vinification with skins, the decrease was on average 62%. The presence of this fungicide on grapes and in the wine did not affect alcoholic and malolactic fermentation, nor did fermentation cause any degradation of the fungicide. A simple and rapid gas chromatograhic method (GC-NPD) for the determination of fenhexamid residues in grapes, must and wine is described.
Assuntos
Aminofenóis/análise , Fungicidas Industriais/análise , Resíduos de Praguicidas/análise , Rosales/química , Vinho/análise , Aminofenóis/farmacocinética , Análise de Variância , Cromatografia Gasosa , Fermentação , Fungicidas Industriais/farmacocinética , HumanosRESUMO
In this study, three flor strains of Saccharomyces cerevisiae were genetically characterized. They were isolated from biofilms on Sardinian sherry-like wines produced at family-run wineries where pure cultures of yeasts were not used. The study aimed to investigate the life cycle of these naturally-occurring flor strains, using a genetic procedure supplemented by analysis of subsequent meiotic generations. A semi-homothallic life cycle was found in three strains that could be helpful in a genetic improvement programme.
Assuntos
Saccharomyces cerevisiae/genética , Vinho/microbiologia , Itália , Saccharomyces cerevisiae/isolamento & purificação , Esporos FúngicosRESUMO
Quinoxyfen is a new fungicide that belongs to the family of the quinolines, recently introduced to control powdery mildew (Uncinula necator). In this paper the fate of quinoxyfen residues from vine to wine and in their processing products was studied. After the last of four applications at the recommended rate, 0.38 mg/kg of residue was found on the grapes, which is under the legal limit fixed in Italy (0.5 mg/kg). The degradation rate was according to a pseudo-first-order kinetics (r = 0.964) and the half-life was 7.24 days. Vinification was carried out with and without maceration. During the vinifications without maceration <50% of the residues passed from the grapes to the musts. Separation of the lees (8%) from the must by centrifugation caused no detectable residues in centrifuged must. At the end of fermentation with and without maceration no quinoxyfen residues were determinable in the wine. No effect on the alcoholic or malolactic fermentation was observed even in the presence of higher quinoxyfen concentrations than those found in the grapes at harvest time. During fermentation, the yeasts partially degraded the pesticides and completly adsorbed them. Bacteria, on the other hand, do not have any degradative effect on the pesticides. The raisins obtained by sun-drying did not contain any residues, whereas those obtained by oven-drying show the same amount of residues as in the fresh grapes. During the sun-drying process the fruit weight decreased by a factor of 4; the decrease in the oven-drying was equivalent. Samples of dregs and liquid lees, fortified with high levels of quinoxyfen. were double-distilled. The first dregs distillate, with an alcohol content of 32.1%, did not show any residues, whereas the first lees distillate, with an alcohol content of 34.5%, showed 7% of the initial residues. After the second lees distillation, the obtained product showed an alcoholic content of 81.2% and no residues of quinoxyfen (<0.01 mg/kg).
Assuntos
Manipulação de Alimentos , Resíduos de Praguicidas/análise , Rosales/química , Vinho/análise , Fungicidas Industriais/análise , QuinolinasRESUMO
Measurement of lymphocyte proliferation to detect hypersensitivity to beryllium (Be-LPT) in vitro is done presently using a method based on tritiated thymidine incorporation. Although this method is sensitive it gives no information on cell viability or responding lymphocyte subsets. We have developed reliable and simple flow cytometric assays for lymphocyte proliferation testing (Immuno-Be-LPT) by combining immunophenotyping with bromodeoxyuridine (BrdU) incorporation or DNA content using propidium iodide (PI) or 4'6'-diimidazolin-2-phenylindole (DAPI). Evaluation of beryllium-induced lymphocyte proliferation in blood cells from seven patients with chronic beryllium disease (CBD) and 120 beryllium workers by both the Bc-LPT and the Immuno-Be-LPT showed agreement between the tests. The Immuno-Bc-LPT provided additional information about the specific type of lymphocytes responding. CD4+ lymphocytes proliferated in response to beryllium in blood samples from all seven CBD individuals and CD8+ lymphocytes proliferated in six of the seven. Four beryllium workers without CBD had positive responses to beryllium primarily in the CD8+ cells. The use of the individual's own plasma supported a greater beryllium or tetanus-induced proliferation of CD4+ lymphocytes when compared to commercial human serum. The response of CD4+ lymphocytes measured in the Immuno-Be-LPT may provide a new marker for the diagnosis of CBD.
Assuntos
Berílio/toxicidade , Linfócitos/efeitos dos fármacos , Anticorpos Monoclonais , Antígenos CD/biossíntese , Antígenos de Diferenciação de Linfócitos T/biossíntese , Biomarcadores , Bromodesoxiuridina/metabolismo , Divisão Celular/efeitos dos fármacos , Doença Crônica , DNA/biossíntese , DNA/metabolismo , Citometria de Fluxo , Corantes Fluorescentes , Humanos , Lectinas Tipo C , Luz , Doenças Profissionais/imunologia , Fenótipo , Espalhamento de Radiação , Linfócitos T Auxiliares-Indutores/efeitos dos fármacos , Linfócitos T Auxiliares-Indutores/imunologia , Linfócitos T Reguladores/efeitos dos fármacos , Linfócitos T Reguladores/imunologia , Toxoide Tetânico/farmacologiaRESUMO
The influence of six fungicides (azoxystrobin, cyprodinil, fludioxonil, mepanipyrim, pyrimethanil, and tetraconazole) on the fermentative activity of two yeasts (Saccharomyces cerevisiae and Kloeckeraapiculata) and two lactic bacteria (Leuconostoc oenos and Lactobacillus plantarum) was studied. The possibility of their being degraded by these yeasts and bacteria was also investigated. The presence of the pesticides did not affect alcoholic fermentation, not even with levels higher than those normally found in grapes in field experiments. On the contrary, their presence stimulated the yeast, especially K. apiculata, to produce more alcohol. The fermentative process did not affect the amount of pesticides either by degradation or by adsorption. During malolactic fermentation by Le. oenos, malic acid decreased slightly less (by approximately 15%) in the presence of all pesticides, except mepanipyrim. A lower effect ( approximately 5%) was found during the fermentative process with La. plantarum. The bacteria studied did not show a degradative effect on pesticides during malolactic fermentation.
Assuntos
Resíduos de Drogas/farmacologia , Manipulação de Alimentos , Fungicidas Industriais/farmacologia , Vinho , Dioxóis/farmacologia , Fermentação , Lactobacillus/efeitos dos fármacos , Leuconostoc/efeitos dos fármacos , Pirimidinas/farmacologia , Pirróis/farmacologia , Saccharomyces cerevisiae/efeitos dos fármacos , Leveduras/efeitos dos fármacosRESUMO
The 1990 Clean Air Act Amendments require that oxygenates be added to automotive fuels to reduce emissions of carbon monoxide and hydrocarbons. One potential oxygenate is the aliphatic ether ethyl tertiary butyl ether (ETBE). Our objective was to provide data on the potential toxic effects of ETBE. Male and female Fisher 344 rats and CD-1 mice were exposed to 0 (control), 500, 1750, or 5000 ppm of ETBE for 6 h/day and 5 days/wk over a 13-week period. ETBE exposure had no effect on mortality and body weight with the exception of an increase in body weights of the female rats in the 5000-ppm group. No major changes in clinical pathology parameters were noted for either rats or mice exposed to ETBE for 6 (rats only) or 13 weeks. Liver weights increased with increasing ETBE-exposure concentration for both sexes of rats and mice. Increases in kidney, adrenal, and heart (females only) weights were noted in rats. Degenerative changes in testicular seminiferous tubules were observed in male rats exposed to 1750 and 5000 ppm but were not seen in mice. This testicular lesion has not been reported previously for aliphatic ethers. Increases in the incidence of regenerative foci, rates of renal cell proliferation, and alpha2u-globulin containing protein droplets were noted in the kidneys of all treated male rats. These lesions are associated with the male rat-specific syndrome of alpha2u-globulin nephropathy. Increases in the incidence of centrilobular hepatocyte hypertrophy and rates of hepatocyte cell proliferation were seen in the livers of male and female mice in the 5000-ppm group, consistent with a mitogenic response to ETBE. These two target organs for ETBE toxicity, mouse liver and male rat kidney, have also been reported for methyl tertiary butyl ether and unleaded gasoline.
Assuntos
Poluentes Atmosféricos/toxicidade , Etil-Éteres/toxicidade , Administração por Inalação , alfa-Globulinas/metabolismo , Animais , Câmaras de Exposição Atmosférica , Peso Corporal/efeitos dos fármacos , Medula Óssea/efeitos dos fármacos , Medula Óssea/patologia , Bromodesoxiuridina/metabolismo , Divisão Celular/efeitos dos fármacos , Feminino , Rim/efeitos dos fármacos , Rim/metabolismo , Rim/patologia , Nefropatias/induzido quimicamente , Nefropatias/metabolismo , Nefropatias/patologia , Fígado/efeitos dos fármacos , Fígado/metabolismo , Fígado/patologia , Masculino , Éteres Metílicos/toxicidade , Camundongos , Tamanho do Órgão/efeitos dos fármacos , Ratos , Ratos Endogâmicos F344 , Túbulos Seminíferos/efeitos dos fármacos , Túbulos Seminíferos/patologia , Testes de ToxicidadeRESUMO
A transgenic mouse line (Tg.AC) carrying an activated v-Ha-ras oncogene fused to the embryonic zeta-globin promoter develops an array of spontaneous epithelial and mesenchymal neoplasms. In this report we describe the morphological, immunophenotypic, and molecular features of a unique hematopoietic neoplasm in these mice. The cardinal lesion of this disease is marked hepatomegaly due to leukemic proliferation and infiltration. In the peripheral blood, there is a marked increase in the number of metarubricytes and other less differentiated erythroid progenitor cells. Leukemic cells stain positively with an erythroid-associated nuclear transcription factor (GATA-1). Using a reverse transcription polymerase chain reaction assay, co-expression of GATA-1 and endogenous zeta-globin genes is detected in hematopoietic tissues of nonleukemic transgenic and nontransgenic mice. ras transgene expression is, however, detected only in normal bone marrow and leukemic tissues of transgenic mice, and 5' mapping experiments using S1 protection analysis of total RNA from leukemic tissue indicates that transcription of the transgene mRNA is initiated from the natural zeta-globin promoter start site, supporting the belief that the zeta-globin promoter directs v-Ha-ras expression in erythroid progenitor cells, ultimately leading to leukemic transformation.
Assuntos
Genes ras/genética , Leucemia Eritroblástica Aguda/genética , Leucemia Eritroblástica Aguda/patologia , Animais , Contagem de Células Sanguíneas , Células Sanguíneas/metabolismo , Medula Óssea/metabolismo , Proteínas de Ligação a DNA/metabolismo , Fatores de Ligação de DNA Eritroide Específicos , Fator de Transcrição GATA1 , Globinas/metabolismo , Leucemia Eritroblástica Aguda/metabolismo , Fígado/metabolismo , Fígado/patologia , Camundongos , Camundongos Transgênicos , Tamanho do Órgão , Reação em Cadeia da Polimerase , Baço/metabolismo , Baço/patologia , Fatores de Transcrição/metabolismo , Transcrição Gênica , Proteínas ras/metabolismoRESUMO
The inhalation of benzene is toxic to various components of the immunologic system in rodents. Spleen and thymus weights, total spleen and femur marrow cell counts, enumeration of spleen B- and T-lymphocytes, and an assessment of humoral immunocompetence, were used to evaluate the immunotoxicity of benzene in male Sprague-Dawley rats. Rats were exposed to 0, 30, 200 or 400 ppm benzene for 6 h/day, 5 days/week for 2 or 4 weeks. An early indicator of immunotoxicity was a reduction in the number of B-lymphocytes after 2 weeks of 400 ppm. After 4 weeks of 400 ppm, there was a reduction in thymus weight and spleen B-, CD4+/CD5+ and CD5+ T-lymphocytes. Rats exposed to 30, 200 or 400 ppm benzene for 2 or 4 weeks and challenged with sheep red blood cells developed a humoral response comparable to that of the control (0 ppm) animals. Enumeration of spleen T- and B-lymphocytes in rats exposed to benzene and challenged with SRBC showed only a transient reduction in spleen B-lymphocytes after 2 weeks of exposure to 400 ppm. These data suggest that there are no immunotoxicological effects of exposure to 200 ppm benzene or less, in rats exposed for 6 h/day, 5 days/week for 2 or 4 weeks.