10-MV SBRT FFF IRRADIATION TECHNIQUE IS ASSOCIATED TO THE LOWEST PERIPHERAL DOSE: THE OUTCOME OF 142 TREATMENT PLANS FOR THE 10 MOST COMMON TUMOUR LOCATIONS

There is a growing interest in the combined use of Stereotactic Body Radiation Therapy (SBRT) with Flattening Filter Free (FFF) due to the high local control rates and reduced treatment times, compared to conventionally fractionated treatments. It has been suggested that they may also provide a better radiation protection to radiotherapy patients as a consequence of the expected decrease in peripheral doses. This work aims to determine this reduction in unattended out-of-field regions, where no CT information is available but an important percentage of second primary cancers occur. For that purpose, ten different cases suitable for SBRT were chosen. Thus, 142 different treatment plans including SBRT, as well as 3D-CRT, IMRT and VMAT (with standard fractionation) in low and high energies for Varian (FF and FFF), Siemens and Elekta machines were created. Then, photon and neutron peripheral dose in 14 organs were assessed and compared using two analytical models. For the prostate case, uncomplicated and cancer free control probability estimation was also carried out. As a general behavior, SBRT plans led to the lowest peripheral doses followed by 3D-CRT, VMAT and IMRT, in this order. Unflattened beams proved to be the most effective in reducing peripheral doses, especially for 10 MV. The obtained results suggest that FFF beams for SBRT with 10 MV represent the best compromise between dose delivery efficiency and peripheral dose reduction.

Bioactivity of essential oils in phytopathogenic and post-harvest fungi control

Commercial thyme and lavender essential oils were analysed by GC/MS. Sixty-six compounds accounting for 98.6-99.6% of total essential oil were identified. Thymol (52.14 ± 0.21%), followed by p-cymene (32.24 ± 0.16%), carvacrol (3.71 ± 0.01%) and γ-terpinene (3.34 ± 0.02%), were the main compounds in thyme essential oil, while large amounts of oxygenated monoterpenes linalool acetate (37.07 ± 0.24%) and linalool (30.16 ± 0.06%) were found in lavender one. In vitro antifungal activity of the essential oils was evaluated at 200 and 300 μg/mL against 10 phytopathogenic and post-harvest fungi, which significantly affect agriculture. Micelial growth inhibition was calculated for each tested fungus and dose. Thyme essential oil showed satisfactory results with 90-100% growth inhibition in almost all the assayed fungi at 300 μg/mL, while lavender essential oil showed no noteworthy inhibition data at either dose, and its growth was even enhanced. Thyme essential oil represents a natural alternative to control harvest and post-harvest fungi, and to extend the shelf-life of agriculture products.

Recombination in liquid-filled ionization chambers beyond the Boag limit

PURPOSE

The high mass density and low mobilities of charge carriers can cause important recombination in liquid-filled ionization chambers (LICs). Saturation correction methods have been proposed for LICs. Correction methods for pulsed irradiation are based on Boag equation. However, Boag equation assumes that the charge ionized by one pulse is fully collected before the arrival of the next pulse. This condition does not hold in many clinical beams where the pulse repetition period may be shorter than the charge collection time, causing overlapping between charge carriers ionized by different pulses, and Boag equation is not applicable there. In this work, the authors present an experimental and numerical characterization of collection efficiencies in LICs beyond the Boag limit, with overlapping between charge carriers ionized by different pulses.

METHODS

The authors have studied recombination in a LIC array for different dose-per-pulse, pulse repetition frequency, and polarization voltage values. Measurements were performed in a Truebeam Linac using FF and FFF modalities. Dose-per-pulse and pulse repetition frequency have been obtained by monitoring the target current with an oscilloscope. Experimental collection efficiencies have been obtained by using a combination of the two-dose-rate method and ratios to the readout of a reference chamber (CC13, IBA). The authors have also used numerical simulation to complement the experimental data.

RESULTS

The authors have found that overlap significantly increases recombination in LICs, as expected. However, the functional dependence of collection efficiencies on the dose-per-pulse does not change (a linear dependence has been observed in the near-saturation region for different degrees of overlapping, the same dependence observed in the nonoverlapping scenario). On the other hand, the dependence of collection efficiencies on the polarization voltage changes in the overlapping scenario and does not follow that of Boag equation, the reason being that changing the polarization voltage also affects the charge collection time, thus changing the amount of overlapping.

CONCLUSIONS

These results have important consequences for saturation correction methods for LICs. On one hand, the two-dose-rate method, which relies on the functional dependence of the collection efficiencies on dose-per-pulse, can also be used in the overlapping situation, provided that the two measurements needed to feed the method are performed at the same pulse repetition frequency (monitor unit rate). This result opens the door to computing collection efficiencies in LICs in many clinical setups where charge overlap in the LIC exists. On the other hand, correction methods based on the voltage-dependence of Boag equation like the three-voltage method or the modified two-voltage method will not work in the overlapping scenario due to the different functional dependence of collection efficiencies on the polarization voltage.

SU-E-T-466: TCP and NTCP: Is That All?

PURPOSE

Concerns about the secondary cancer risks associated to the peripheral neutron and photon contamination in photon modern radiotherapy (RT) techniques (e.g., Intensity Modulated RT -IMRT- or Intensity Modulated Arc Therapy -IMAT) have been widely raised. Benefits in terms of better tumor coverage have to be balanced against the drawbacks of poorer organ at risk sparing and secondary cancer risk in order to make the decision on the optimum treatment technique. The aim of this study was to develop a tool which estimates treatment success taking into consideration the neutron secondary cancer probability.

METHODS

A methodology and benchmark dataset for radiotherapy real time assessment of patient neutron dose and application to a novel digital detector (DD) has been carried out (submitted to PMB, 2011). Our DD provides real time neutron equivalent dose distribution in relevant organs along the patient. This information, together with TCP and NTCP estimated from the DVH of target and organs at risks, respectively, have been built into a general biological model which allows us to evaluate the success of the treatments (Sánchez-Nieto et al., ESTRO meeting 2012). This model has been applied to make estimation of treatment success in a variety of treatment techniques (3DCRT, forward and inverse IMRT, RapidArc, Volumetric Modulated Arc Therapy and Helical Tomotherapy) to low and high energy.

RESULTS

MU-demanding techniques at high energies were able to deliver treatment plans with the highest complicated-free tumour control. Nevertheless, neutron peripheral dose must be taken into consideration as the associated risk could be of the same order of magnitude than the usually considered NTCPs.

CONCLUSIONS

The methodology developed to provide an online organ neutron peripheral dose can be successfully combined with biological models to make predictions on treatment success taking into consideration secondary cancer risks.

Inhibition of adult hippocampal neurogenesis disrupts contextual learning but spares spatial working memory, long-term conditional rule retention and spatial reversal

Neurogenesis in the adult dentate gyrus (DG) of the hippocampus has been implicated in neural plasticity and cognition but the specific functions contributed by adult-born neurons remain controversial. Here, we have explored the relationship between adult hippocampal neurogenesis and memory function using tasks which specifically require the participation of the DG. In two separate experiments several groups of rats were exposed to fractionated ionizing radiation (two sessions of 7 Gy each on consecutive days) applied either to the whole brain or focally, aiming at a region overlying the hippocampus. The immunocytochemical assays showed that the radiation significantly reduced the expression of doublecortin (DCX), a marker for immature neurons, in the dorsal DG. Ultrastructural examination of the DG region revealed disruption of progenitor cell niches several weeks after the radiation. In the first experiment, whole-brain and focal irradiation reduced DCX expression by 68% and 43%, respectively. Whole-brain and focally-irradiated rats were unimpaired compared with control rats in a matching-to-place (MTP) working memory task performed in the T-maze and in the long-term retention of the no-alternation rule. In the second experiment, focal irradiation reduced DCX expression by 36% but did not impair performance on (1) a standard non-matching-to-place (NMTP) task, (2) a more demanding NMTP task with increasingly longer within-trial delays, (3) a long-term retention test of the alternation rule and (4) a spatial reversal task. However, rats irradiated focally showed clear deficits in a "purely" contextual fear-conditioning task at short and long retention intervals. These data demonstrate that reduced adult hippocampal neurogenesis produces marked deficits in the rapid acquisition of emotionally relevant contextual information but spares spatial working memory function, the long-term retention of acquired spatial rules and the ability to flexibly modify learned spatial strategies.

Activated extracellular signal-regulated kinases: association with epidermal growth factor receptor/transforming growth factor alpha expression in head and neck squamous carcinoma and inhibition by anti-epidermal growth factor receptor treatments

The expression of the activated mitogen-activated kinases/extracellular signal-regulated kinases (ERKs) ERK1 and ERK2 was characterized in 101 humanhead and neck squamous carcinoma specimens. Activated ERK1/2were detected at different levels in the majority of these tumors, as assayed by immunostaining with an antibody specific for the dually phosphorylated and activated ERK1 and ERK2. ERK1/2 activation levels were higher in tumors with advanced regional lymph node metastasis (P = 0.048) and in relapsed tumors (P = 0.021). The expression of epidermal growth factor (EGF) receptor (P = 0.037), transforming growth factor alpha (TGF-alpha; P < 0.001), and HER2 (P = 0.066; positive trend) correlated with activation of ERK1/2. In a multivariate analysis, both TGF-alpha (P < 0.0001) and HER2 (P = 0.045) were independently correlated with ERK1/2 activation. In turn, activation of ERK1/2 was associated with a higher Ki-67 proliferative index (P = 0.002). In EGF receptor-dependent model cells (A431 and DiFi), a specific EGF receptor tyrosine kinase inhibitor ("Iressa"; ZD1839) and a chimeric anti-EGF receptor antibody ("Cetuximab"; C225) inhibited ERK 1/2 activation at concentrations that inhibited autocrine cell proliferation. In patients on treatment with C225, the activation of ERK1/2 in skin, an EGF receptor-dependent tissue, was lower compared with control skin. Parallel changes were seen in keratinocyte Ki67 proliferation indexes in skin from C225-treated patients. Taken together, these studies provide support for a role of activation of ERK1/2 in head and neck squamous carcinoma and a correlation with EGF receptor/TGF-alpha expression. The inhibition of ERK1/2 activation in vitro and in vivo by compounds targeting the EGF receptor points to the interest of ERK1/2 as potential surrogate markers of EGF-receptor signaling in clinical therapeutic studies.

Salivary and lacrimal gland dysfunction (sicca syndrome) after radioiodine therapy

Salivary gland dysfunction has been described in patients undergoing radioiodine therapy but associated lacrimal gland dysfunction (sicca syndrome) has never been reported. We conducted a prospective cohort study with follow-up for up to 3 y in a tertiary care university center to determine the prevalence of sicca syndrome in patients after high-dose radioiodine treatment.

METHODS

From January 1990 to December 1995, all patients undergoing radioiodine therapy (n = 79) with a standard dose of 925 MBq to 18.5 GBq (25-500 mCi) were interviewed using a standardized questionnaire to determine subjective ocular and oral dryness and were examined for objective lacrimal and salivary gland dysfunction.

RESULTS

After radioiodine treatment, 32.9% of the patients reported subjective xerostomia and 25.3% reported subjective xerophthalmia in the first year of follow-up. Xerostomia persisted to the second year of follow-up in 20.3% of cases and was still present >3 y after the last dose of radioiodine in 15.2% of cases. Xerophthalmia persisted to the second year of follow-up in 17.7% of cases and was still present in the third year of follow-up in 13.9% of cases. Severe xerostomia occurred in 4 patients. Reduced salivary and lacrimal gland function was documented in 40 (50.6%) and 14 (17.7%) of the 79 cases, respectively, in the first year of follow-up. Objective xerostomia persisted in 13.9% of cases to the second year of follow-up and was still present in all patients >3 y after the last radioiodine application. Keratoconjunctivitis sicca persisted in 11 patients (13.9%) to the second year of follow-up but was only present in 6 patients (7.6%) >3 y after the last radioiodine application. Additionally, 28/79 patients (35.4%) who had a normal salivary gland scintigraphy previously showed reduced salivary gland function in the third year of follow-up. No significant dependence on cumulative treatment was found for objective xerostomia or xerophthalmia, but doses >11.1 GBq (300 mCi) were related to stage 3 dysfunction on salivary gland scintigraphy.

CONCLUSION

Salivary and lacrimal gland dysfunction (sicca syndrome) is relatively frequent after radioiodine therapy. In most cases this is a transient side effect, but in some patients it may persist for a long period or appear late.

[Antibiotic prophylaxis in oncologic pharyngolaryngeal surgery: ceftriaxone versus clindamycin and gentamycin]

There are many papers comparing two antibiotic protocols for the profilaxis of head and neck infections after laryngeal surgery. We present one prospective and randomised study in 60 patients comparing the efficacy of two protocols. The comparison was between ceftriaxone versus the association of clindamicyn and gentamicyn. In our database we included the risk factors for infection, the surgical approach, the duration of surgery and the patient characteristics. We observed an incidence of 28% of infection, with a 23.3% in the clindamicyn + gentamicyn group and a 33.3% in the ceftriaxone group. The differences between the two groups were not statistically significant. In this study we observed a small difference between the amount of alcohol comsuption, the effectiveness of the surgical drainage, the surgical approach and the presence of wound infection. The difference was not statistical significant due to the small group of patients. The profilaxis was adequate for the total laryngectomy and cordectomy group, with a higher incidence of wound infection in patients treated with a supraglottic laryngectomy.

[Analysis of factors associated with anticoagulant treatment indication in chronic atrial fibrillation. Prospective study of 170 patients admitted at an internal medicine service]

BACKGROUND

Anticoagulant therapy reduces the risk of stroke among patients with chronic atrial fibrillation. The objective of this study was to evaluate the use of anticoagulant therapy and to analyze the factors associated with the indication of anticoagulants in patients with chronic atrial fibrillation.

PATIENTS AND METHODS

Prospective study of all patients with chronic atrial fibrillation admitted to our Department of Internal Medicine from February 1997 to September 1998. From each patient data related to the cause of atrial fibrillation, other associated vascular risk factors, use of anticoagulant and/or antiplatelet agents and contraindication to anticoagulants were recorded.

RESULTS

A total of 170 patients with chronic atrial fibrillation were studied. The mean age of patients was 77 years (range: 49-94). One hundred and four patients (61%) were older than 75 years. Atrial fibrillation was the main cause for admission only in 11 patients (6.5%). One hundred and sixty-seven patients (98%) had indication for receiving anticoagulant therapy; however, it was indicated in only 67 patients (39%). In other 68 patients (40%), antiplatelet agents were used. Patients over 75 years received anticoagulants less frequently (p < 0.0001). Factors associated with the prescription of anticoagulants in the bivariate analysis included: diabetes mellitus (p = 0.046), high cholesterol level (p = 0.023), age < or = 75 years old (p < 0.0001), history of previous embolic events (p = 0.001) and valvular atrial fibrillation (p < 0.0001). The multivariate analysis showed that only two factors were indeed associated with the prescription of anticoagulants: age < or = 75 years (OR: 6.15) and valvular atrial fibrillation (OR: 4.24).

CONCLUSIONS

Anticoagulant therapy is underused in patients with chronic atrial fibrillation, particularly in elderly patients.

Modulation of vasoconstrictor and dilator pancreatic metabolites in streptozotocine diabetic rats: effect of bradykinin blockage and NO inhibition

This study was designed to investigate the effect of HOE 140 (a bradykinin beta2 receptor antagonist) and N(w)-nitro-L-arginine methyl-ester (L-NAME, a nitric oxide synthase inhibitor) on endothelial and beta-cell function in induced streptozotocine (Stz) diabetic rats. The decrease in the insulinogenic index after Stz effect (control 286.03+/-104.12 and Stz 18.22+/-10.77, P<0.001 vs. Control) was partially prevented by L-NAME (46.54+/-10.12, P<0.001) and HOE 140 (105.12+/-23.06, P<0.001). It was observed in diabetic rats: L-NAME increased the pancreatic endothelin-1 (ET-1) production and HOE 140 did not. L-NAME and HOE 140 decreased the nitric oxide (NO) synthesis, increased prostacyclin 1-2 (PGI2), and did not modify thromboxane A-2 (TxA2). These results indicate that L-NAME and HOE 140 had a protective effect on the development of diabetes in the rat. The protective effect of L-NAME and HOE 140 on the insulinogenic index could be related to ET-1, bradykinin, PGI2, and NO.

Adverse effects of chronic low level lead exposure on kidney function--a risk group study in children

BACKGROUND

Children have been considered a risk group for lead (Pb) toxicity, mainly because of neurophysiological or neuro-cognitive deficits following Pb exposure. Blood Pb levels (b-Pb) of 100 microg/l currently have been defined as the lowest adverse effect level. The aim of this study was to compare, with the help of urinary markers, the kidney function of children with b-Pb just above this threshold with that of unexposed children, to assess from a nephrological point of view whether the current threshold is justified and whether children really are a particularly vulnerable risk group in terms of Pb-induced kidney damage.

METHODS

In a cross-sectional study, 112 children, either from unexposed areas (controls, n=50) or Pb-contaminated areas (n=62), the latter partly with a known history of elevated b-Pb, were examined. Twenty nine urinary or serum markers mostly related to the function or integrity of specific nephron segments were determined (e.g. filtered plasma proteins, tubular enzymes, tubular antigens, eicosanoids).

RESULTS

b-Pb were 39+/-13 microg/l in controls and 133+/-62 microg/l in exposed children. The main findings were increased excretion rates of prostaglandins and thromboxane B2, epidermal growth factor, beta2-microglobulin and Clara cell protein in the exposed children. A relationship between b-Pb and the prevalence of values above the upper reference limits was observed.

CONCLUSIONS

With the help of urinary markers, nephron segment-specific effects of chronic low-level Pb exposure could be detected in children. The pattern of effects on glomerular, proximal and distal tubular and interstitial markers was similar to that previously observed in adults. The changes, however, occur at lower b-Pb levels than in adults. The current threshold appears to be justified also from a nephrological point of view, and children can indeed be considered a special risk group.

Arachidonic acid metabolites in CSF in hypoxic-ischaemic encephalopathy of newborn infants

The aim of this study was to evaluate the cerebral synthesis of eicosanoids in the asphyctic newborn and to investigate the relation between the prostanoid profiles in cerebrospinal fluid (CSF) and the appearance and severity of hypoxic-ischaemic encephalopathy (HIE). Levels of 6-keto-PGF(1-alpha), TXB2, PGE2 and PGF(2-alpha), in CSF were measured in 40 full term newborns during the first day of life. Thirty of these newborns had birth asphyxia and were divided into three groups: 10 without HIE, 12 with mild HIE and 8 with moderate-severe HIE. They were compared to a control group of 10 non-hypoxic newborns. Determinations of the metabolites in CSF were performed by RIA and expressed as pg/ml (mean +/- SD). The CSF TXB2 (thromboxane A2 metabolite) in asphyxiated newborns was always higher than in the control group (28.12 +/- 10.6), and related to the severity of HIE (p = 0.005): without HIE (50.84 +/- 16.4; p = 0.02), mild HIE (80.65 +/- 12.64; p < 0.01) and moderate-severe HIE (178.14 +/- 20.5; p < 0.01). The CSF 6-keto-PGF(1-alpha) (prostacyclin metabolite) in asphyxiated newborns was always higher than in the control group (80.55 +/- 12.56), but indirectly related to the severity of HIE: without HIE (240.95 +/- 28.12; p < 0.01), mild HIE (183.65 +/- 30.1; p < 0.01) and moderate-severe HIE (140.55 +/- 25.12; p < 0.01). In the moderate-severe HIE group, the increase in TXB2 was higher than the rise in 6-keto-PGF(1-alpha).

[Prevalence of arterial hypertension and other cardiovascular risk factors among hospital workers]

BACKGROUND

The attitude of sanitary workers is essential for the control of arterial hypertension (HT). The aim of the study was to identify the prevalence of HT and some cardiovascular risk factors in both sanitary and non-sanitary hospital workers and the knowledge, therapeutic compliance and control of hypertense individuals.

SUBJECTS AND METHODS

Two tensional measurements were obtained by using a manometer of mercury at the beginning and at the end of an epidemiological request. A logistic regression model was obtained to evaluate the association between HT and risk factors.

RESULTS

One thousand and one individuals (762 females) with a median age of 37.2 years were studied. Prevalence of HT was 9.7%. Men showed a higher age-related prevalence than women (19.7 vs 6.6%, p < 0.001). Body mass index was higher in HT individuals. Thirty eight per cent of the hospital workers were smokers. HT prevalence increased with alcohol consumption. Sex, mass body index and age were significantly associated with HT. Knowledge, therapeutic compliance and control of HT were 73.2, 19.7 and 28%, respectively, in the total group and 61, 26.3 and 0%, respectively, in the group of physicians and nurses.

CONCLUSIONS

Hospital workers showed a high prevalence of cardiovascular risk factors. Inadequate therapeutic and control measures were observed on both nurses and physicians with high blood pressure.

Prevention and control of nosocomial infections in Spain: current problems and future trends

Spain is a state member of the European Union, with more than 180,000 hospital beds and 800 public and private institutions. Only 6.9% of our gross national product is devoted to health expenditures. All citizens receive free health care through the National Health System. This system has given increasing attention to the prevention and control of nosocomial infections since 1986. In this article, results of serial prevalence surveys of antibiotic use and resistance patterns of microorganisms isolated from nosocomial infections are discussed. The needs for future development of infection control and quality assurance training programs in Spain also are discussed. Overall, a clinically and epidemiologically oriented approach to infection control is preferred, with greater emphasis in the role of infection control practitioners and infection control committees.

Improving survival of medulloblastoma: results in two groups of patients

This retrospective study compares the results obtained in 56 children with medulloblastoma treated with two different protocols at our center between 1975 and 1990. Since 1985 we have been enrolled in the medulloblastoma SIOP II protocol in which we have entered 27 patients. These patients from the SIOP group (SG) and the 29 children treated before 1985, the historical group (HG). When the two groups were compared for age and sex distribution, no differences were found; however, prognostic factors were worse in the HG than in SG: 21 versus 15 T3-T4 and 13 versus 8 high-risk, respectively. The relapse rate was 63% for the HG and 39% for the SG. Five-year disease-free survival was 31% for the HG and 56% for the SG (p = 0.037). Five-year survival was 52 and 70%, respectively (p = 0.055). When SG and HG were compared by stratifying for tumor size, surgical resection and the risk variable, better disease-free survival was obtained in SG than in HG. In a multivariate analysis, the HG and the high-risk proved to be variable independent predictors of poor survival. We observe an increase in survival in our patients with medulloblastoma.

Altered levels of urinary prostanoids in lead-exposed workers

This paper describes the alteration of the urinary excretion of prostanoids in workers occupationally exposed to lead. For this purpose, the following groups were studied: Group 1 (n = 62): controls; Group 2 (n = 29): risk group; and Group 3 (n = 69): exposed group. Urine samples were collected for prostanoid analysis and lead blood levels were analyzed. Our results demonstrate that urinary excretion of prostanoids is already altered even at levels of lead in blood = 200 micrograms/l. Owing to their sensitivity, urinary prostanoids could be useful markers of early renal changes associated with lead exposure. However, underlying mechanisms should be elucidated and the health significance of such changes should be assessed before any conclusion is drawn.

Markers of early renal changes induced by industrial pollutants. II. Application to workers exposed to lead

The present study has been carried out in the framework of a collaborative research project on the development of new markers of nephrotoxicity. A battery of more than 20 potential indicators of renal changes has been applied to 50 workers exposed to lead (Pb) and 50 control subjects. After application of selection criteria 41 exposed and 41 control workers were eventually retained for the final statistical analysis. The average blood Pb concentration of exposed workers was 480 micrograms/l and their mean duration of exposure was 14 years. The battery of tests included parameters capable of detecting functional deficits (for example, urinary proteins of low or high molecular weight), biochemical alterations (for example, urinary eicosanoids, glycosaminoglycans, sialic acid) or cell damage (for example, urinary tubular antigens or enzymes) at different sites of the nephron or the kidney. The most outstanding effect found in workers exposed to Pb was an interference with the renal synthesis of eicosanoids, resulting in lower urinary excretion of 6-keto-PGF1 alpha and an enhanced excretion of thromboxane (TXB2). The health significance of these biochemical alterations, detectable at low exposure to Pb is unknown. As they were not associated with any sign of renal dysfunction, they may represent reversible biochemical effects or only contribute to the degradation of the renal function from the onset of clinical Pb nephropathy. The urinary excretion of some tubular antigens was also positively associated with duration of exposure to Pb. Another effect of Pb that might deserve further study is a significant increase in urinary sialic acid concentration.

Markers of early renal changes induced by industrial pollutants. I. Application to workers exposed to mercury vapour

Several markers of renal changes have been measured in a cohort of 50 workers exposed to elemental mercury (Hg) and in 50 control workers. After application of selection criteria 44 exposed and 49 control workers were retained for the final statistical analysis. Exposed workers excreted on average 22 micrograms Hg/g creatinine and their mean duration of exposure was 11 years. Three types of renal markers were studied--namely, functional markers (creatinine and beta 2-microglobulin in serum, urinary proteins of low or high molecular weight); cytotoxicity markers (tubular antigens and enzymes in urine), and biochemical markers (eicosanoids, thromboxane, fibronectin, kallikrein, sialic acid, glycosaminoglycans in urine, red blood cell membrane negative charges). Several bloodborne indicators of polyclonal activation were also measured to test the hypothesis that an immune mechanism might be involved in the renal toxicity of elemental Hg. The main renal changes associated with exposure to Hg were indicative of tubular cytotoxicity (increased leakage of tubular antigens and enzymes in urine) and biochemical alterations (decreased urinary excretion of some eicosanoids and glycosaminoglycans and lowering of urinary pH). The concentrations of anti-DNA antibodies and total immunoglobulin E in serum were also positively associated with the concentration of Hg in urine and in blood respectively. The renal effects were mainly found in workers excreting more than 50 micrograms Hg/g creatinine, which corroborates our previous estimate of the biological threshold of Hg in urine. As these effects, however, were unrelated to the duration of exposure and not accompanied by functional changes (for example, microproteinuria), they may not necessarily represent clinically significant alterations of renal function.

Human and experimental studies on renal eicosanoid response to long-term cadmium exposure

In order to assess the effects of long-term exposure to cadmium (Cd) on the renal metabolism of eicosanoids, the urinary excretion of 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha), prostaglandin E2 (PGE2), prostaglandin F2 alpha (PGF2 alpha), and thromboxane B2 (TXB2) was determined in 37 workers exposed to Cd and in female Sprague-Dawley rats given 100 ppm Cd in drinking water for 10 months. Urinary output of sodium and calcium was also determined. The Cd-exposed workers showed an increased urinary concentration of 6-keto-PGF1 alpha, PGE2, sodium, and calcium. The rise of 6-keto-PGF1 alpha was related to Cd levels in blood and weakly correlated with urinary sodium. Calcium in urine was not related to the concentration of the metal in blood and urine. A slight elevation in urinary TXB2 was also observed in workers with blood Cd higher than 5 micrograms/liter. After 10 months of exposure to Cd, female Sprague-Dawley rats presented an enhanced urinary excretion of albumin, transferrin, beta 2-microglobulin, sodium, and PGE2 in urine. The latter was significantly correlated with albuminuria and transferrinuria. In conclusion the results show that chronic exposure to Cd induces changes in the urinary excretion of some eicosanoids. The possible relation of these changes to Cd-induced kidney dysfunction are discussed.

Gas chromatographic/mass spectrometric analysis of high-performance liquid chromatographic fractions reflecting arachidonic acid metabolism in mouse peritoneal macrophages

Mouse peritoneal macrophages are used as a model for studies undertaken around the oxidative metabolism of arachidonic acid elicited by xenobiotics (N-phenyllinoleamide, related to the toxic oil syndrome, has been used as an example). A high-performance liquid chromatographic method for cyclo- and lipoxygenase metabolite fractionation has been developed. Gas chromatographic/mass spectrometric analysis of the high-performance liquid chromatographic fractions thus obtained show that the major products detected in the incubates correspond to three principal structures: monohydroxy acids (12-hydroxyeicosatetraenoic acid being the major component), epoxyhydroxy acids and trihydroxy acids. Other minor compounds such as 12-hydroxyheptadecatrienoic acid, various dihydroxy acids and prostaglandins were also detected. Cells pre-exposed to N-phenyllinoleamide show selectively enhanced levels of 6-keto prostaglandin F1 alpha, as measured by both gas chromatography/mass spectrometry and radioimmunoassay of the corresponding high-performance liquid chromatographic fraction.

Systemic prostacyclin in cirrhotic patients. Relationship with portal hypertension and changes after intestinal decontamination

The total body production of prostacyclin was shown to be increased in cirrhotic patients, suggesting that its synthesis by blood vessels of the systemic circulation is enhanced. However, the mechanism by which the synthesis of systemic prostacyclin is stimulated is not known. The present study investigated the urinary excretion of 2,3-dinor-6-keto-PGF1 alpha, an index of total body prostacyclin synthesis, first, in cirrhotics with portal hypertension (n = 19) as compared with cirrhotics with reduced portal pressure after portacaval shunt surgery (n = 18) and with control noncirrhotic subjects (n = 11), and; second, in cirrhotics before and after intestinal decontamination by oral nonabsorbable antibiotics (n = 9 antibiotic treated patients, n = 10 control nontreated cirrhotics). Control noncirrhotic subjects showed lower urinary excretion of 2,3-dinor-6-keto-PGF1 alpha than both groups of cirrhotics (P less than 0.001). Interestingly, urinary excretion of 2,3-dinor-6-keto-PGF1 alpha was significantly higher in cirrhotics with portacaval shunt than in those with portal hypertension (P less than 0.01). The urinary excretion of 2,3-dinor-6-keto-PGF1 alpha decreased significantly after intestinal decontamination in the antibiotic-treated group (580.1 +/- 232.4 vs. 431.2 +/- 219.2 pg/mg creatinine; P less than 0.05) but not in nontreated patients (543.9 +/- 214.4 vs. 581.2 +/- 281.4 pg/mg creatinine; P = NS). These data suggest that the increased urinary excretion of 2,3-dinor-6-keto-PGF1 alpha observed in cirrhotics is not directly related to portal hypertension itself but to portal blood factors that bypass the liver. Some such factors may be of intestinal bacterial origin.

Cyclooxygenase products of metabolism of arachidonic acid in mouse macrophages exposed to N-phenyllinoleamide from toxic oil samples

N-phenyllinoleamide (NPLA), one of the major extraneous constituents of Spanish toxic oil samples, appears to enhance the cyclooxygenase metabolic pathway of arachidonic acid by peritoneal mouse macrophages. Results reported herein show an increased biosynthesis of 6-oxo-PGF1 alpha and TXB2 by macrophages exposed to NPLA. However, light and electron microscopy failed to show cellular alterations in macrophages incubated with NPLA for two hours at 27 degrees C. These data suggest a possible involvement of cyclooxygenase arachidonic acid metabolism in the etiopathogenesis of the Spanish Toxic Oil Syndrome.

Modern high-performance liquid chromatographic-radioimmunoassay strategies for the study of eicosanoids in biological samples

An evaluation of the most recent literature on the determination of eicosanoids by immunoassay methods confirms that owing to the inherent lack of specificity of many of the antibodies used for this purpose, immunological assays (radioimmunoassay or enzyme immunoassay) are often preceded by solid-phase extraction followed by further purification of the antigens of interest by routine reversed-phase high-performance liquid chromatographic methods. In this way the analytical potential of radioimmunoassay is remarkably enhanced and accuracy and precision of the assay are ensured.

Increased synthesis and production of prostaglandin E2 by monocytes from drug addicts with AIDS

We analysed the production of prostaglandin E2 (PGE2) by monocytes in 11 drug addicts with AIDS and opportunistic infections and in 13 controls. In three patients and six controls we isolated the PGE2 fraction from culture supernatants of purified monocytes (greater than 95%) incubated in medium containing (3H) arachidonic acid, using silicic acid columns. In two of three patients PGE2-fraction values (21.9 and 21.6 pmol/g protein) were significantly higher than controls (10 +/- 4). In eight AIDS patients and seven controls, PGE2 levels were determined by high-performance liquid chromatography and radioimmunoassay (HPLC and RIA). In three out of eight patients PGE2 levels were markedly higher (736, 419 and 208 pg/ml) than the mean + 2 s.d. values from controls (73 +/- 51). We tested the effect of PGE2 on the production of interleukin-2 by normal phytohemagglutinin-stimulated peripheral blood lymphocytes (PBL). There was a significant suppression of interleukin-2 production by PGE2 released from AIDS monocytes. PGE2 may be one of the factors involved in the severe immune dysfunction associated with AIDS.

PGE2 and PGF2 alpha in the nasal lavage fluid from healthy subjects: methodological aspects

Prostaglandins E2 and F2 alpha were estimated in nasal secretions from ten healthy volunteers by high performance liquid chromatography and radioimmunological assay. Prostaglandin concentrations determined in five consecutive nasal washes with saline at room temperature showed that the nasal mucosa was stimulated after instillation. A substantial increase of basal levels was associated with the second nasal lavage. In all volunteers aspirin treatment inhibited prostaglandin release.

Determination of oxidation products of N-phenyllinoleamide: Spanish toxic oil syndrome studies

The early identification of fatty acid anilides in suspect oils directed attention to their possible role in the Spanish toxic oil syndrome. These anilides or their oxidized derivatives could have been spontaneously formed during the handling and/or storage of the oil. The exact cause of the intoxication is still unknown but free radical and peroxidative mechanisms have been implicated in its etiology. Epoxy-hydroxylated derivatives from linoleic acid anilide were obtained using a model of accelerated oxidation. Their mass spectral patterns agree with the trimethylsilyl ethers of N-phenyl-9,10-epoxy-11-hydroxy-12-octadecenamide and N-phenyl-12,13-epoxy-11-hydroxy-9-octadecenamide, respectively. These compounds were also identified is rapeseed oil samples supplemented with N-phenyl-linoleamide and submitted to the reported accelerated oxidation method.

Cyclooxygenase and lipoxygenase-like activity in Drosophila melanogaster

To determine the possible activity of cyclooxygenase and lipoxygenase like enzymes in Drosophila melanogaster, we have investigated whether fly homogenates can biosynthesize prostaglandins and HETEs. Incubation of fly extracts with AA yields a mixture of 15- 12- 9- and 8-HETE as detected by selected ion monitoring GC-MS. Also the combination of HPLC-RIA using a PGE antibody shows the presence of endogenous PGE2 immunoreactivity in the extracts (405 pg/g in males and 165 pg/g in females). We have also detected the presence of lipoxygenase like immunoreactivity in the reproductive male system by using immunocytochemical techniques in whole body sections of the fly as well as reactivity in the digestive system of both males and females. Finally, we have not been able to detect endogenous AA in the fly by GC-MS methods. However, estimates by GC-MS of the total body fatty acids indicate substantial amounts of potential AA precursors.

Quantitative profiling of the metabolic cascade of arachidonic acid by capillary gas chromatography mass spectrometry

The analytical approach described allows for the rapid screening and concurrent quantitative determination of all of the major metabolites of the cyclooxygenase pathway of arachidonic acid, including the primary prostaglandins PGE2, PGD2 and PGF2 alpha in addition to the stable end-products of short-lived prostacyclin and thromboxane A2 (6-keto-PGF1 alpha and TXB2, respectively), generated by incubating arachidonic acid with mouse peritoneal macrophage cells. After derivatization into the corresponding methyl ester-methoxime-TMS derivative, the extracted endogenous compounds were analysed by combined high efficiency glass capillary column chromatography and selected ion monitoring. Comparatively lower detection limits can be achieved with the methyl ester-butylboronate-TMS derivatives (e.g. 10 pg for 6-keto-PGF1 alpha). A brief account is also presented on a new type of mixed methyl ester-pentafluorobenzyloxime-butylboronate-TMS derivative of TXB2 and 5-keto-PGF1 alpha.