Proteinuria due to suboptimal hydration with high-dose methotrexate therapy

One of the major complications after high-dose methotrexate (HDMTX) infusions is renal damage. We investigated the occurrence of proteinuria after HDMTX administration in children with pediatric malignancies (acute lymphoid leukaemia, osteosarcoma Burkitt's lymphoma). In the period 1989–1990 we gave 52 HDMTX courses to 24 children. During this period, prehydration and extra urinary alkalisation were performed only if the urinary specific gravity was over 1010 or if the urinary pH fell below 7. Using this schedule the mean values obtained for protein extraction were: before the therapy, 0.12±0.03 g/m²; on day 1 after MTX treatment, 0.38±0.06 g/m²; and on day 2 after the MTX infusion, 0.39±0.11 g/m² (P<0.01). A significant increase in proteinuria (>0.2 g/m² post- vs pretreatment) was detectable in 54% of the patients. In the period 1991–1992 we modified the hydration-alkalisation schedule to include i. v. prehydration for 18–24 h at 3 l/m²/day with a 0.45% NaCl-5% glucose solution along with sodium bicarbonate and posthydration for 72 h with the same solution. On this protocol the mean values determined for the urinary protein content were all in the normal range (pretreatment, 0.03 g/m²/day; day 1, 0.05 g/m²/day; and day 2, 0.08 g/m²/day). These findings were significantly different from the previous results (P<0.05).     

Leukemic ophthalmopathy: A report of 21 pediatric cases

A multicentric retrospective study on leukemic ophthalmopathy (LO) is reported. It includes 21 patients, 16 males and 5 females, with acute leukemia (AL) observed in 10 SIOP centers. LO developed in three patients at the time of diagnosis of AL; five patients were in first complete remission (three off therapy); four patients were in second or third remission; and nine were in combined relapse. Most frequent symptoms were blurred vision, photophobia, and ocular pain. Two patients with acute nonlymphoblastic leukemia died before treatment; another underwent bone marrow transplantation; one patient with B-cell acute lymphoblastic leukemia (B-ALL) treated with chemotherapy and radiotherapy died 4 months after LO; the remaining 17 children were treated according to different schedules with (10) or without (7) radiotherapy on the affected eye. Twelve patients achieved ocular remission and four of these had a second ocular relapse. Complete remission after LO treatment lasting for more than 3, 7, 24, 29 months was observed in four patients. The authors conclude that cure is possible in patients who had LO in first complete remission treated with chemotherapy and radiotherapy at high dose on the affected eye. © 1994 Wiley-Liss, Inc.     

Development of a 32P-postlabelling method for the detection of 1,N 2-propanodeoxyguanosine adducts of crotonaldehyde in vivo

Crotonaldehyde is a genotoxic, mutagenic and carcinogenic alpha,beta-unsaturated carbonyl compound which forms 1,N2-propanodeoxyguanosine adducts. Humans are exposed to this compound at work places, and from tobacco smoke and air pollution, but also from food and beverages. Therefore crotonaldehyde can play a significant role in carcinogenesis. Since in vivo measurement of DNA adducts of crotonaldehyde can improve cancer risk assessment and contribute to the clarification of the role of crotonaldehyde in carcinogenicity, we developed, adapted and optimized a 32P-postlabelling technique for the adducts of crotonaldehyde based on nuclease P1 enrichment and on a polyethylene imine modified cellulose TLC to provide a detection sensitivity of three adducts per 10(9) nucleotides and a labelling efficiency of 80-90%. We also report a readily performable synthesis of adduct standards and demonstrated that DNA is completely digested to the 3'-monophosphate nucleotides under the conditions of our enzymatic DNA hydrolysis. We showed that the postlabelling method developed is appropriate for in vivo DNA-binding studies. Female Fischer 344 rats were treated by gavage with crotonaldehyde at doses of 200 and 300 mg/kg body weight, and 20 h after treatment adduct levels of 2.9 and 3.4 adducts per 10(8) nucleotides, respectively, were found in the liver DNA. Only 1.6 nucleotides per 10(8) nucleotides were found 12 h after treatment at 200 mg/kg body weight. Absolutely no adducts could be found in liver DNA of untreated rats with our method at the detection limit of three adducts per 10(9) nucleotides. In contrast to our group, the group of Chung have reported crotonaldehyde adduct levels in the range of 2.2 22 adducts per 10(8) nucleotides in DNA of untreated Fischer 344 rats. The clarification of this discrepancy is of importance for the elucidation of the role of crotonaldehyde in carcinogenicity, and both groups have decided to clarify this in cooperation in the near future.     

Mitogenic signaling of Ras is regulated by differential interaction with Raf isozymes

In the mitogenic signaling cascade interaction of Ras with Raf represents a critical step for the regulation of cell growth and differentiation. The major effector of Ras, the serine/threonine kinase Raf exists as three isoforms with different tissue distributions. We demonstrate that transient transfection of oncogenic Ha-Ras leads to a preferential activation of endogenous c-Raf-1 in HEK 293 cells as opposed to A-Raf. In vitro binding studies using purified Ras binding domains of Raf as well as in vivo bindings tests with full length molecules reveals significantly lower binding affinities of A-Raf to Ha-Ras as compared to other Raf isoforms. The Ras-binding interface of c-Raf differs from A-Raf by a conservative Arg to Lys exchange at residue 59 or 22 respectively. Mutational analysis reveals that this residue represents a point of isozyme discrimination: c-Raf-R59K binds Ha-Ras weaker than the wildtype, likewise A-Raf-K22R increases its affinity to Ha-Ras in vivo and in vitro. Differential binding affinities are reflected in downstream signaling. Immunecomplex kinase assays reveal that Ha-Ras mediated Raf activation is decreased for c-Raf-R59K and increased for A-Raf-K22R when compared to the respective wildtype forms. Thus our observations introduce a new level of isoform discrimination in Ras/Raf signaling as a functional consequence of a conservative amino acid exchange in the Ras binding domains.     

Simultaneous Orthotopic Liver and Kidney Transplant with Repair of Abdominal Aortic Aneurysm: Operative Timing

In the case of coexisting abdominal aortic aneurysm (AAA) and liver/renal failure, the controversial issue is the timing of the AAA repair and the transplantation of the affected organs. The question is whether to repair the AAA first and perform the double transplantation at a later time, or to perform all three procedures in the same operative session. This patient was affected by hepatic/renal failure and had also developed AAA. We describe the operative strategies utilized to perform the cadaver donor and recipient operations in this setting. In our patient, a combined liver/kidney transplantation with simultaneous aneurysm repair using arterial allografts was successfully performed. In a patient affected by end-stage liver, kidney, and aneurysmatic disease, a simultaneous liver/kidney transplant and AAA repair may represent the safest and most efficient treatment solution.     

Regional myocardial dysfunction: evaluation of patients with prior myocardial infarction with fast CT

A prototype ultrafast cine computed tomographic (CT) scanner, designed specifically for cardiac imaging, was used to evaluate a preliminary series of patients with prior myocardial infarction (n = 21) and a control group without coronary artery disease (n = 5). Multilevel 50-msec CT scan exposures were obtained during peripheral intravenous bolus injections of contrast medium. A comparison was made between cine-CT scans and standard left ventriculographic images in assessing segmental left ventricular motion. Results indicate that cine CT, performed at sufficiently rapid speeds (20 scans per second) to allow useful analysis of regional ventricular wall motion, can provide adequate image quality. Analysis of 110 segments revealed a good correlation (90.9%) between the two techniques in characterizing normal from abnormal regional wall motion. Cine CT, based on this initial study, demonstrates considerable potential for evaluating not only cardiac chamber dimensions but also segmental wall dynamics.     

Effects of Crude Oil and Diesel Exposures on Biochemical Activities of Polymorphonuclear Leukocytes in Cattle

Cattle exposed to low doses of an Alberta crude oil, Pembina Cardium crude oil (PCCO), or a winter diesel oil no. 2 (WDO-2) were assessed for their biochemical activities in polymorphonuclear leukocyte (PMNL) cells (mainly neutrophils). The study used a randomized block design containing five treatment groups (8 animals/group). The animals were dosed per gavage with the test substance on study days 0, 14, 28, and 42. The dosages given (on per kg body weight) were: Group 1 (control), 10 mL/kg of potable water; Group 2, 5 mL/kg WDO-2; Group 3, 2.5 mL/kg PCCO; Group 4, 5 mL/kg PCCO; and Group 5, 10 mL/kg PCCO. Blood was collected at the specified intervals during the pre- and post-exposure periods, and the biochemical activities of isolated PMNL were analyzed. Cattle groups exposed to WDO-2 and PCCO showed moderate and statistically significant reductions (p < 0.01) in the activities of (1) phorbol myristate acetate (PMA) stimulated cellular respiration (respiratory burst), (2) NADPH-oxidase (PMA-stimulated production of superoxide anion), (3) myeloperoxidase, and (4) n-acetylglucosidase as compared to the control group. These biochemical parameters also showed statistically significant (p < 0.01) dose-related periodic (study day) trends. In general, these biochemical activities were decreased after each dosing; however, they subsequently recovered to near the pre-dosing levels. Such a biochemical response in PMNL provides a valuable biological tool to follow exposure effects in cattle accidentally exposed to low doses of petroleum hydrocarbons.     

Joint Toxicity of Triazine Herbicides and Organophosphate Insecticides to the Midge Chironomus tentans

A series of recent studies demonstrated that the triazine herbicide atrazine, although not itself acutely toxic, potentiated the toxicity of certain organophosphate insecticides (OPs) to the midge Chironomus tentans. In the current study, a series of triazine herbicides and triazine herbicide degradation products were tested to determine if other triazines potentiate OP toxicity to midges. Chlorpyrifos and diazinon were the OPs tested. Toxicity tests were conducted using a factorial design and analysis of variance to statistically determine if each triazine had an effect on expected toxicity. Log-probit procedures were also used to evaluate the magnitude of change in median effective concentration (EC₅₀) values during coexposure with each triazine. All of the triazine herbicides tested (atrazine, simazine, cyanazine, and hexazinone) were capable of potentiating the toxicity of the OPs, whereas the degradation products (s-triazine, deethylatrazine, and deisopropylatrazine) had less effect. In most cases, a triazine concentration of 100 μg/L was necessary to significantly increase OP toxicity, and higher concentrations of triazine caused a greater degree of potentiation. Changes in EC₅₀ values ranged from no change to a 2.5-fold increase in toxicity. Generally, EC₅₀ values changed by less than a factor of 2, indicating that the effect may be of limited concern in regard to future risk assessments of OPs.