Organophosphorus pesticide degradation product in vitro metabolic stability and time-course uptake and elimination in rats following oral and intravenous dosing.

Levels of urinary dialkylphosphates (DAPs) are currently used as a biomarker of human exposure to organophosphorus insecticides (OPs). It is known that OPs degrade on food commodities to DAPs at levels that approach or exceed those of the parent OP. However, little has been reported on the extent of DAP absorption, distribution, metabolism and excretion. The metabolic stability of O,O-dimethylphosphate (DMP) was assessed using pooled human and rat hepatic microsomes. Time-course samples were collected over 2 h and analyzed by LC-MS/MS. It was found that DMP was not metabolized by rat or pooled human hepatic microsomes. Male Sprague-Dawley rats were administered DMP at 20 mg kg(-1) via oral gavage and i.v. injection. Time-course plasma and urine samples were collected and analyzed by LC-MS/MS. DMP oral bioavailability was found to be 107 ± 39% and the amount of orally administered dose recovered in the urine was 30 ± 9.9% by 48 h. The in vitro metabolic stability, high bioavailability and extent of DMP urinary excretion following oral exposure in a rat model suggests that measurement of DMP as a biomarker of OP exposure may lead to overestimation of human exposure.

Roles of uptake, biotransformation, and target site sensitivity in determining the differential toxicity of chlorpyrifos to second to fourth instar Chironomous riparius (Meigen).

Early life stages of aquatic organisms tend to be more sensitive to various chemical contaminants than later life stages. This research attempted to identify the key biological factors that determined sensitivity differences among life stages of the aquatic insect Chironomous riparius. Specifically, second to fourth instar larvae were exposed in vivo to both low and high waterborne concentrations of chlorpyrifos to examine differences in accumulation rates, chlorpyrifos biotransformation, and overall sensitivity among instars. In vitro acetylcholinesterase (AChE) assays were performed with chlorpyrifos and the metabolite, chlorpyrifos-oxon, to investigate potential target site sensitivity differences among instars. Earlier instars accumulated chlorpyrifos more rapidly than later instars. There were no major differences among instars in the biotransformation rates of chlorpyrifos to the more polar metabolites, chlorpyrifos-oxon, and chlorpyridinol (TCP). Homogenate AChE activities from second to fourth instar larvae were refractory to chlorpyrifos, even at high concentrations. In contrast, homogenate AChE activities were responsive in a dose-dependent manner to chlorpyrifos-oxon. In general, it appeared that chlorpyrifos sensitivity differences among second to fourth instar C. riparius were largely determined by differences in uptake rates. In terms of AChE depression, fourth instar homogenates were more sensitive to chlorpyrifos and chlorpyrifos-oxon than earlier instars. However, basal AChE activity in fourth instar larvae was significantly higher than basal AChE activity in second to third instar larvae, which could potentially offset the apparent increased sensitivity to the oxon.

Epithelioid sarcoma: clinical, MR imaging and pathologic findings.

OBJECTIVE: To report and describe the MR imaging features of eight new cases of this rare soft tissue sarcoma and correlate them with the clinical and histologic findings. DESIGN AND PATIENTS. Retrospective analysis was carried out for the MR imaging characteristics and histologic findings of eight patients with pathologically proven epithelioid sarcoma and the literature was reviewed. Findings were correlated in each case with the patient's clinical presentation and eventual outcome. RESULTS: The patients, whose primary tumors ranged from 2.5 cm to 19 cm in maximum dimension, were 1 to 90 years of age. Tumors involved the extremities ( n=5), the scalp ( n=2) and the paraspinal muscles ( n=1). Five tumors presented as well-defined, frequently painful, deeply situated masses and three as subcutaneous nodules or cutaneous ulcers with no palpable mass. Four patients had associated regional lymphadenopathy and one had distant metastases at diagnosis. MR imaging showed tumor infiltration of adjacent tissues in seven patients. Signal characteristics reflected varying degrees of cellularity, and the presence of necrosis, hemorrhage, fibrosis, hyalinization and inflammation. Bone marrow involvement was demonstrated in one patient. Clinical outcomes were generally poor. CONCLUSIONS: Epithelioid sarcoma is an aggressive soft tissue sarcoma with a varied clinical presentation, growth pattern, MR signal characteristics and histologic picture. The tumor favors the distal extremities and is commonly infiltrative and accompanied by enlarged regional lymph nodes. This neoplasm may present as an intramuscular mass but should also be suspected in patients with ulcerating cutaneous nodules with or without regional lymphadenopathy.

A test system to evaluate the susceptibility of Oregon, USA, native stream invertebrataes to triclopyr and carbaryl.

The susceptibility of six indigenous macroinvertebrate species representative of U.S. Pacific Northwest streams (Ameletus sp., Brachycentrus americanus, Calineuria californica, Cinygma sp., Lepidostoma unicolor, Psychoglypha sp. early and late instar) to formulated triclopyr ester (herbicide) and carbaryl (insecticide) was determined using laboratory bioassays. Acute toxicity was expressed as the lethal concentration to 50% (LC50) and 1% (LC1) of the test population based on a 96-h exposure duration. Carbaryl was found to be 1,000 times more toxic than triclopyr for all the organisms tested. The LCI values (7.5, 28.8, 9.0, 3.0, 9.5, 14.8, 33.8 microg/L, respectively, for carbaryl and 1.8, 3.9, 4.0, 4.2, 29.0, 16.1 mg/L, respectively, for triclopyr) were used in the calculation of hazardous concentration to 5% of the stream macroinvertebrate community (HC5) based on the lower 95% confidence limit (HC5/95). The hazardous concentration (HC5/95) for triclopyr was 0.11 mg/L and for carbaryl ranged from 0.43 to 0.66 microg/L, respectively. Triclopyr and carbaryl symptomology were analyzed for two organisms, C. californica and Cinygma sp. Carbaryl symptomology included knockdown and moribund states with severity and time of appearance being a function of dose. In triclopyr poisoning, death occurred suddenly with little or no symptomology. Time to 50% mortality (LT50) values were consistently higher for C. californica than for Cinygma sp. exposed to both chemicals at similar concentrations.

Effect of varying pesticide exposure duration and concentration on the toxicity of carbaryl to two field-collected stream invertebrates, Calineuria californica (Plecoptera: Perlidae) and Cinygma sp (Ephemeroptera: Heptageniidae).

The effect of exposure duration on the toxicity of a forest insecticide (carbaryl) was assessed under environmentally realistic exposure regimes against two stream invertebrates indigenous to the United States Pacific Northwest, Calineuria californica (Plecoptera: Perlidae) and Cinygma sp. (Ephemeroptera: Heptageniidae). Laboratory bioassays were conducted to evaluate the relationship between pulsed exposures of 15, 30, and 60 min and toxicity for a range of chemical concentrations (10.2-1,730 microg/L). For Cinygma sp., the 50% lethal concentration (LC50) values were calculated as 848 microg/L (15 min), 220 microg/L (30 min), and 165 microg/L (60 min). The C. californica consistently had lower mortality at a given concentration compared with Cinygma sp. Fifteen- and 30-min exposures did not elicit 50% mortality with C. californica, and it had a 60-min LC50 of 1,139 microg/L. Time to 50% mortality over 96 h after a 15-, 30-, or 60-min exposure, with the rest of the test period in freshwater (PLT50), was a function of exposure duration and concentration. Analysis of symptomology throughout the test period for C. californica gave evidence of recovery from the knockdown and moribund states, but this was not the case for Cinygma sp. The pulse duration resulting in 50% mortality was calculated as 43 min for Cinygma sp. exposed at 204 microg/L and 16 min at 408 microg/L. A three-dimensional probit plane model [Y = -10.86 + 4.83(ln C) + 3.0(ln T)], where Y is probit mortality, C is concentration in microg/L and T is time in hours, was used to explain the interaction between concentration (microg/L) and duration of exposure (hours) for Cinygma sp.

Atrazine remediation in wetland microcosms.

Laboratory wetland microcosms were used to study treatment of atrazine in irrigation runoff by a field-scale-constructed wetland under controlled conditions. Three experiments, in which 1 ppm atrazine was added to the water column of three wetland, one soil control, and one water control microcosm, were conducted. Atrazine dissipation from the water column and degradate formation (deethylatrazine [DEA]; deisopropylatrazine [DIA]; and hydroxyatrazine [HA]) were monitored. Atrazine dissipation from the water column of wetland microcosms was biphasic. Less than 12% of the atrazine applied to wetland microcosms remained in the water column on day 56. Atrazine degradates were observed in water and sediment, with HA the predominant degradate. Analysis of day 56 sediment samples indicated that a significant portion of the initial application was detected as the parent compound and HA. Most probable number (MPN) assays demonstrated that atrazine degrader populations were small in wetland sediment. Wetland microcosms were able to reduce atrazine concentration in the water column via sorption and degradation. Based on results from this study, it is hypothesized that plant uptake contributed to atrazine dissipation from the water column.

Use of reverse transcriptase polymerase chain reaction for diagnosis and staging of alveolar rhabdomyosarcoma, Ewing sarcoma family of tumors, and desmoplastic small round cell tumor.

PURPOSE: To compare the use of reverse transcriptase polymerase chain reaction (RT-PCR) with that of morphology-based methods for diagnosis, staging, and detection of metastatic disease in pediatric alveolar rhabdomyosarcoma (ARMS), Ewing sarcoma family of tumors (ESFT), and desmoplastic small round cell tumors (DSRCT). MATERIALS AND METHODS: RT-PCR assays for the EWS-FLII, EWS-ERG, PAX3-FKHR, PAX7-FKHR, and EWS-WTI fusion transcripts were performed on RNA extracted from the primary tumor tissue, bone marrow, and body fluids obtained at initial presentation and relapse. Molecular findings were compared with original histologic diagnoses and results of staging procedures. RESULTS: Eighty-eight samples from 47 patients with ARMS (n = 13), ESFT (n = 31), or DSRCT (n = 3) were analyzed. The detection rate of metastatic disease was significantly higher with RT-PCR (95%) as compared with the morphologic methods (70%) for the three pediatric sarcomas studied. In primary tumors with characteristic fusion transcript, RT-PCR was positive in all cases with morphologic evidence of metastatic disease. Moreover, in six patients (3 with ARMS, 2 with DSRCT, and 1 with ESFT) with metastatic disease, micrometastases in bone marrow (4) and other sites (2) were detected by RT-PCR alone. Importantly, none of the patients with localized disease diagnosed had micrometastases detected by RT-PCR in bone marrow. CONCLUSIONS: The high sensitivity and specificity of RT-PCR for the characteristic fusion transcripts of pediatric sarcomas make it an ideal method to aid in the routine staging of these patients. In addition, the 100% sensitivity of RT-PCR in detection of micrometastasis makes it useful for follow-up and detection of minimal residual disease. However, the clinical significance of molecularly-detectable disease remains unknown. Further studies should aim to elucidate the therapeutic and prognostic implications of micrometastases detected by RT-PCR alone.

Carboplatin/ifosfamide window therapy for osteosarcoma: results of the St Jude Children's Research Hospital OS-91 trial.

PURPOSE: To determine the activity of carboplatin/ifosfamide in patients with previously untreated osteosarcoma and to estimate patient outcomes after a multiagent chemotherapy protocol that eliminated cisplatin. PATIENTS AND METHODS: Sixty-nine patients with newly diagnosed, previously untreated osteosarcoma received three cycles of carboplatin (560 mg/m(2) x 1) and ifosfamide (2.65 g/m(2)/d x 3). Assessment of response was evaluated after two (week 6) and three (week 9) chemotherapy cycles. At week 9, histologic response was assessed. Adjuvant therapy comprised two additional carboplatin/ifosfamide cycles, doxorubicin, and high-dose methotrexate. Patients were stratified at enrollment: stratum A, resectable primary tumor without metastases; stratum B, unresectable primary tumor; and stratum C, metastatic disease at diagnosis. Week 6 response was compared with that of a historic group that received only ifosfamide during the initial window evaluation. RESULTS: The clinical and radiographic response rate to three cycles of carboplatin/ifosfamide was 67.7% (95% confidence interval, 55.0% to 78.8%). Compared with the historic population who received only ifosfamide, the combination of carboplatin and ifosfamide reduced the progressive disease rate at week 6 (31.9% v 9%, P: = .003). For patients in stratum A, the 3-year event-free survival and survival were 72.3% +/- 6.7% and 76.4% +/- 6.4%, respectively. Patients who received carboplatin-based therapy had less long-term renal toxicity and ototoxicity. CONCLUSION: This pilot trial suggests that carboplatin/ifosfamide combination chemotherapy has substantial antitumor activity. In the context of a multiagent chemotherapy protocol comprising high-dose methotrexate and doxorubicin, we found that the addition of carboplatin/ifosfamide resulted in patient outcomes comparable to trials using cisplatin-based therapy with less long-term toxicity.

Atrazine degradation by bioaugmented sediment from constructed wetlands.

The potential to establish pesticide biodegradation in constructed wetland sediment was investigated. Under microcosm conditions, bioaugmentation of sediment with small quantities of an atrazine spill-site soil (1:100 w/w) resulted in the mineralization of 25-30% of 14C ethyl atrazine (1-10 microg g(-1) sediment) as 14CO2 under both unsaturated and water-saturated conditions; atrazine and its common metabolites were almost undetectable after 30 days incubation. By comparison, unbioaugmented sediment supplemented with organic amendments (cellulose or cattail leaves) mineralized only 2-3% of 14C ethyl atrazine, and extractable atrazine and its common metabolites comprised approximately 70% of the original application. The population density of atrazine-degrading microorganisms in unbioaugmented sediment was increased from approximately 10(2)/g to 10(4)/g by bioaugmentation (1:100 w/w), and increased by another 60-fold (6.0x10(5) g(-1)) after incubation with 10 microg g(-1) of atrazine. A high population of atrazine degraders (approximately 10(6) g(-1)) and enhanced rates of atrazine mineralization also developed in bioaugmented sediment after incubation in flooded mesocosms planted with cattails (Typha latifolia) and supplemented with atrazine (3.2 mg l(-1), 1 microg g(-1) sediment). In the absence of atrazine, neither the population of atrazine degraders, nor the atrazine mineralizing potential of bioaugmented sediment increased, regardless of the presence or absence of cattails. Bioaugmentation might be a simple method to promote pesticide degradation in nursery run-off channeled through constructed wetlands, if persistence of degraders in the absence of pesticide is not a serious constraint.

Hepatitis C infection and hepatocellular carcinoma after treatment of childhood cancer.

The results of preliminary reports of childhood cancer survivors with hepatitis C infection (HCV) show that in none of these patients did the disease progress to liver failure or hepatocellular carcinoma (HCC). The authors describe two patients who were diagnosed with HCC more than 20 years after the treatment of childhood acute lymphocytic leukemia. Serologic testing, done at the time HCC was diagnosed, found HCV-directed antibodies, suggesting that chronic HCV infection contributed to the development of the subsequent neoplasm. Identification of infected patients will permit intervention to reduce the risk of progressive liver disease and will also assist in defining the risk of and variables contributing to progressive liver disease.

Non-hematopoietic cutaneous metastases in children and adolescents: thirty years experience at St. Jude Children's Research Hospital.

BACKGROUND: The spectrum of cutaneous metastasis of non-hematopoietic neoplasms in the pediatric population is not well documented. We report the histologic diversity of this unusual process over a 30-year period at a tertiary care center for pediatric malignancy (St. Jude Children's Research Hospital, Memphis, TN, USA). METHODS: Of 1,971 pathology accessions which included histologic material on skin (1,604 surgical cases and 367 autopsy cases) we found 40 cases (2% of total skin accessions) coded for metastatic non-hematopoietic malignancy. RESULTS: The patients (n=34) ranged in age from 1 month to 20 years (mean=9.8 years) and had a male:female ratio of 1:1. The histologic diagnoses were as follows: rhabdomyosarcoma NOS (6 cases), embryonal rhabdomyosarcoma (4 cases), alveolar rhabdomyosarcoma (4 cases), neuroblastoma (8 cases), osteosarcoma (2 cases), choriocarcinoma (2 cases), peripheral neuroepithelioma or Ewing's sarcoma (2 cases), malignant rhabdoid tumor (1 case), paraganglioma (1 case), nasopharyngeal carcinoma (1 case), sarcoma NOS (1 case), colon adenocarcinoma (1 case), and malignant melanoma (1 case). CONCLUSIONS: Cutaneous or subcutaneous metastasis of non-hematopoietic malignancies in children and adolescents is a rare occurrence but in a high percentage of cases may be the first manifestation of disease. The tumors most likely to metastasize to the skin in children are rhabdomyosarcoma and neuroblastoma and they are more likely than adult malignancies to disseminate to multiple distant sites.

A fatal case of pancreatic panniculitis presenting in a young patient with systemic lupus.

BACKGROUND: Subcutaneous fat necrosis associated with pancreatic disease is a rare event. The clinical cutaneous findings are non-specific erythematous nodules with central softening located predominantly on the lower extremities. The histopathologic features of these lesions are very characteristic and diagnostic. METHODS: We present an unusual case of pancreatic panniculitis associated with lupus pancreatitis in a 21-year-old African American female. The patient presented with lower extremity skin nodules, arthralgia, and serositis prior to the diagnosis of systemic lupus and pancreatitis. The skin lesions progressed despite normalization of serum pancreatic enzymes. Following femoral vein catheterization for renal dialysis, she developed a large indurated area over the left lower quadrant, flank, groin, and upper thigh measuring 25 cm. She was treated with repeated debridement, tissue grafts, and hyperbaric oxygen because of a clinical suspicion of necrotizing fasciitis. RESULTS: Examination of skin biopsies and debrided tissue revealed the pathognomonic features of pancreatic panniculitis without any evidence of necrotizing fasciitis. Organisms were not detected by tissue examination or microbiologic cultures. CONCLUSIONS: This case illustrates the potential role of vascular trauma in the pathogenesis of pancreatic panniculitis.

Childhood carcinoid tumors: the St Jude Children's Research Hospital experience.

BACKGROUND/PURPOSE: To better characterize childhood carcinoid tumors, the authors reviewed the clinical presentation, treatment, and outcomes of pediatric patients with these rare tumors. METHODS: A retrospective review was conducted of medical records and pathologic materials of all children with carcinoid tumors treated at St Jude Children's Research Hospital between December 1977 and March 1999. RESULTS: Eight patients (median age, 12.7 years) were identified; 2 were boys, and 7 were white. Primary tumor sites were the appendix (n = 5), small intestine (n = 1), bronchus (n = 1), and 1 unknown site. In 7 cases, carcinoid tumor was not suspected at the time the tumor was identified. Seven patients had localized disease; 5 remain disease-free after complete resection, and 2, whose carcinoid tumors were identified incidentally, died of metastatic mucinous adenocarcinoma of the colon. One patient who presented with symptoms of carcinoid syndrome had metastatic disease that responded poorly to cytotoxic chemotherapy and remains alive with active disease. CONCLUSIONS: Although most pediatric carcinoid tumors arise in the appendix, these tumors also occur in other primary sites. Clinical awareness and early diagnosis are important factors in preventing morbidity and mortality. Outcomes are excellent for patients with localized disease that is completely resected, but those with metastatic disease fare poorly. New therapeutic strategies are needed for these patients.

Association of azinphos-methyl with rat erythrocytes and hemoglobin.

To investigate whether hemoglobin might serve as a biomarker of exposure to azinphos-methyl (AZM) encountered by agricultural workers, we exposed rats to [14C]azinphos-methyl ([14C]AZM). We administered single doses of 1.5 mg/kg, 3 mg/kg, or 6 mg/kg of [14C]AZM by gavage to rats and collected blood 3 days later. We found a dose-dependent association between radioactivity and erythrocytes and hemoglobin (measured by liquid scintillation spectrometry). In another experiment, we administered a single dose of 3 mg/kg [14C]AZM by gavage to rats and collected blood 3, 11, 15, and 22 days after administration. Radioactivity continued to be associated with erythrocytes and hemoglobin at all time-points. Brain and plasma acetylcholinesterase (AChE) activities were not significantly inhibited, nor did we observe signs of acute toxicity in any of the treated animals. Loss of radioactivity associated with erythrocytes and hemoglobin over the study period was consistent with the expected kinetics of erythrocyte turnover, indicating adduct stability. Approximately 0.49%, 0.43%, 0.39%, and 0.32% of the original radioactivity was recovered in the hemoglobin 3 11, 15, and 22 days, respectively, after administration. These data support our hypothesis that AZM may form a hemoglobin adduct and may be useful as a biomarker of AZM exposure.

Multiple genomic alterations including N-myc amplification in a primary large cell medulloblastoma.

The large cell (LC) subtype is a recently described histologic variant of medulloblastoma (Mb) associated with a rapid and aggressive clinical course. We describe the genomic profile of a LC-Mb tumor obtained from a patient who developed recurrent and fulminant disease despite 'good-risk' features at diagnosis and state- of-the-art multidisciplinary therapy. The tumor sample was analyzed using comparative genomic hybridization (CGH) and complementary molecular approaches. CGH revealed amplicons at chromosome bands 2p24-25, 2q12-22, and 17p11; losses of chromosomes 11q and 18; and low-level gains of 3q, 11p, 13q and 14q. Southern blot analysis confirmed N-myc amplification. No evidence of p53 mutation was detected. The genomic profile of this LC-Mb tumor sample revealed a distinctive pattern of genetic alterations including amplification of N-myc and anonymous oncogenes at chromosome bands 2q12-22 and 17p11. These genomic abnormalities are uncommon in other subtypes of Mb.

Molecular evidence of ocular Epstein-Barr virus infection.

Ocular manifestations have been attributed to the Epstein-Barr virus (EBV), largely on the basis of seroepidemiologic data. Two patients who developed conjunctival disease as the presenting feature of EBV infection are reported, each confirmed by in situ hybridization of EBV genome in affected tissue biopsy specimens. Recognition of EBV-induced ocular disease as an initial presentation of clinical EBV infection is important to the practitioner because of the ubiquitous nature of this herpesvirus.

Partial phonological marking facilitates the acquisition of noun subclasses: a replication.

This is a partial replication of Brooks, Braine, Catalano, Brody, and Sudhalter (1993). 32 participants learned a miniature linguistic system (MLS). Vocabulary of the MLS consisted of an actor subject, two sets of 19 object nouns, and two sets of three suffixes. In the experimental language, 60% of the nouns were phonologically marked with a common ending for each class; in the control, these endings were distributed across the classes. Participants were trained using pictures. Sentences about the pictures combined the actor's name with an object and an appropriate suffix that described the actor-object relation. A subset of possible sentences and objects was reserved for later testing. During generalization tests, participants had to produce sentences for pictures they had not seen during training. The experimental group was markedly superior to the control. The replication supports the earlier finding that learning of seemingly arbitrary linguistic classes can be facilitated by partial phonological cues.