Combined immunotherapy encompassing intratumoral poly-ICLC, dendritic-cell vaccination and radiotherapy in advanced cancer patients.

Background: Combination immunotherapy has the potential to achieve additive or synergistic effects. Combined local injections of dsRNA analogues (mimicking viral RNA) and repeated vaccinations with tumor-lysate loaded dendritic cells shows efficacy against colon cancer mouse models. In the context of immunotherapy, radiotherapy can exert beneficial abscopal effects. Patients and methods: In this two-cohort pilot phase I study, 15 advanced cancer patients received two 4-week cycles of four intradermal daily doses of monocyte-derived dendritic cells preloaded with autologous tumor lysate and matured for 24 h with poly-ICLC (Hiltonol), TNF-α and IFN-α. On days +8 and +10 of each cycle, patients received intratumoral image-guided 0.25 mg injections of the dsRNA-analogue Hiltonol. Cyclophosphamide 600 mg/m2 was administered 1 week before. Six patients received stereotactic ablative radiotherapy (SABR) on selected tumor lesions, including those injected with Hiltonol. Expression of 25 immune-relevant genes was sequentially monitored by RT-PCR on circulating peripheral blood mononuclear cell (PBMCs) and serum concentrations of a cytokine panel were sequentially determined before and during treatment. Pre- and post-treatment PBMC from patients achieving durable stable disease (SD) were studied by IFNγ ELISPOT-assays responding to tumor-lysate loaded DC and by TCRß sequencing. Results: Combined treatment was, safe and well tolerated. One heavily pretreated castration-resistant prostate cancer patient experienced a remarkable mixed abscopal response to SABR+ immunotherapy. No objective responses were observed, while nine patients presented SD (five of them in the six-patient radiotherapy cohort). Intratumoral Hiltonol increased IFN-ß and IFN-α mRNA in circulating PBMC. DC vaccination increased serum IL-12 and IL-1ß concentrations, especially in patients presenting SD. IFNγ-ELISPOT reactivity to tumor lysates was observed in two patients experiencing durable SD. Conclusions: This radio-immunotherapy combination strategy, aimed at resembling viral infection in tumor tissue in combination with a dendritic-cell vaccine and SABR, is safe and shows immune-associated activity and signs of preliminary clinical efficacy.

Dual Task Performance Is Associated with Amyloidosis in Cognitively Healthy Adults.

BACKGROUND: Preclinical Alzheimer's disease (AD) provides an opportunity for the study and implementation of interventions and strategies aimed at delaying, mitigating, and preventing AD. While this preclinical state is an ideal target, it is difficult to identify efficiently and cost-effectively. Recent findings have suggested that cognitive-motor dual task paradigms may provide additional inference. OBJECTIVES: Investigate the relationship between dual task performance and amyloidosis, suggestive of preclinical Alzheimer's disease and whether dual task performance provides additional information beyond a cognitive composite, to help in the identification of amyloidosis. DESIGN: Cross-sectional. SETTING: Outpatient specialty brain health clinical research institution in the United States. PARTICIPANTS: 52 cognitively healthy adults. MEASUREMENTS: The data included demographics, amyloid standardized uptake value ratio obtained via florbetapir-PET, neuropsychological testing, apolipoprotien E genotype, and dual task performance measures. Data were analyzed via hierarchal multiple linear regression or logistic regression, controlling for age, education, and apolipoprotien E genotype. Receiver operating characteristic curves were plotted, and sensitivity and specificity calculated via 2x2 contingency tables. RESULTS: There was a moderate relationship (rs>.30) between motor and cognitive dual task effects and amyloid standardized uptake value ratio (ps<.042). A strong relationship (r=.58) was found between combined dual task effect, a measure of automaticity derived from dual task performance, and amyloid standardized uptake value ratio (p<.001). Additionally, combined dual task effect showed promise in its unique contributions to amyloid standardized uptake value ratio, accounting for 7.8% of amyloid standardized uptake value ratio variance beyond cognitive composite scores (p=.018). Additionally, when incorporated into the cognitive composite, combined dual task effect resulted in improved diagnostic accuracy for determining elevated amyloid standardized uptake value ratio, and increased the sensitivity and specificity of the cognitive composite. CONCLUSSION: Dual task performance using the combined dual task effect, a measure of automaticity, was a moderate predictor of cerebral amyloidosis, which suggests that it has utility in the screening and diagnosis of individuals for preclinical AD. Additionally, when combined with the cognitive composite, the combined dual task effect improves diagnostic accuracy. Further research is warranted.

Cytostatic and genotoxic effect of temephos in human lymphocytes and HepG2 cells.

Temephos is an organophosphorus pesticide that is used in control campaigns against Aedes aegypti mosquitoes, which transmit dengue. In spite of the widespread use of temephos, few studies have examined its genotoxic potential. The aim of this study was to evaluate the cytotoxic, cytostatic and genotoxic effects of temephos in human lymphocytes and hepatoma cells (HepG2). The cytotoxicity was evaluated with simultaneous staining (FDA/EtBr). The cytostatic and genotoxic effects were evaluated using comet assays and the micronucleus technique. We found that temephos was not cytotoxic in either lymphocytes or HepG2 cells. Regarding the cytostatic effect in human lymphocytes, temephos (10 µM) caused a significant decrease in the percentage of binucleated cells and in the nuclear division index as well as an increase in the apoptotic cell frequency, which was not the case for HepG2 cells. The comet assay showed that temephos increased the DNA damage levels in human lymphocytes, but it did not increase the MN frequency. In contrast, in HepG2 cells, temephos increased the tail length, tail moment and MN frequency in HepG2 cells compared to control cells. In conclusion, temephos causes stable DNA damage in HepG2 cells but not in human lymphocytes. These findings suggest the importance of temephos biotransformation in its genotoxic effect.

Poly ICLC in the treatment of postinfectious demyelinating encephalomyelitis.

Three weeks after a mild and presumably infectious illness, a 21-year-old man developed a CNS disorder characterized by involvement of the cerebellum, cerebrum, and brainstem. It progressed, sometimes stepwise, without remission, over five months to being bedfast with total spastic paraplegia, severe ataxia, and unintelligible dysarthric speech. The CSF showed increased levels of protein, IgG, and myelin basic protein, as well as five oligoclonal bands. Because of failure of the patient's condition to respond to prolonged prednisone therapy, poly ICLC was given intravenously weekly for 20 weeks (median dose, 100 microgram/kg). Improvement, evident after the first dose, progressed to the point of ambulation with some assistance. Even though the relation of the patient's marked recovery to poly ICLC therapy remains unproved, this experience provides reason for considering a possible therapeutic role of the drug in postinfectious demyelinating encephalomyelitis and perhaps in multiple sclerosis.

Predicting posttraumatic epilepsy in penetrating head injury.

Using data derived from a 15-year follow-up study of 520 veterans surviving penetrating brain wounds received in the Vietnam war, we have developed a predictive formula and tables for posttraumatic epilepsy based on time elapsed postinjury and presence of specific clinical and computed tomographic scan risk factors. Such patients remain at some increased risk for epilepsy even ten to 15 years postinjury, although most can be 95% certain of avoiding epilepsy if they have been seizure free for three years posttrauma. Epilepsy onset latency was independent of any risk factors identified.

Isolated impairment of memory following a penetrating lesion of the fornix cerebri.

Persistent memory problems were reported by a 39-year-old man who suffered a penetrating brain wound while serving in Vietnam 15 years earlier. Neuropsychological testing indicated an unusually isolated memory impairment. Computed tomography revealed transection of the columns of the fornix cerebri with no temporal-lobe involvement and minimal thalamic damage. We suggest that the fornix cerebri has a role in the maintenance of information accessibility to both encoding and recall during post-working memory processing and in the organization of verbal information during encoding and/or retrieval for declarative (recall) purposes. These processes are not essential for verbal recognition but can result in decrements on specific laboratory tasks and in social adjustment.

Intrathecally administered natural human fibroblast interferon reduces exacerbations of multiple sclerosis. Results of a multicenter, double-blind study.

A randomized, double-blinded, placebo-controlled, two-year multicenter study demonstrated that natural human fibroblast interferon (interferon beta) administered intrathecally (IT) is effective in reducing the exacerbations of exacerbating-remitting multiple sclerosis (MS). The mean reduction in exacerbation rate of 34 patients with MS who received interferon beta administered IT was significantly greater during the study than that of 35 control patients who received placebo. The prestudy exacerbation rates were comparable for both patients who received interferon beta and control patients, but the exacerbation rate of patients receiving interferon beta at the end of the study was significantly lower than that of the control patients. Interferon beta was administered by nine or ten lumbar punctures for the first six months of the study, and observations were continued for two years. In 95% of the recipients, interferon beta therapy was well tolerated, and the side effects experienced were clearly acceptable for the benefits achieved. Low doses of indomethacin dramatically reduced the toxicity of interferon beta therapy and played an important role in successful double blinding. This study confirms a preliminary report on 20 patients that initially suggested that interferon beta administered IT was of benefit in patients with MS. The number of treatments was fewer and the dosage of interferon beta administered was less in the present study than in the preliminary one. It is possible that even fewer treatments with lower doses of interferon beta administered might provide a similar degree of prophylaxis against exacerbations.

Amyotrophic lateral sclerosis and parkinsonian syndromes in high incidence among the Auyu and Jakai people of West New Guinea.

Amyotrophic lateral sclerosis (ALS) and parkinsonism-dementia (PD) occur in the highest recorded incidence among primitive Auyu and Jakai people on the southern coastal plain of West New Guinea, in association with a heretofore unrecognized subacute, often recurrent, paralytic "poliomyeloradiculitis" (PMR). Ninety-seven cases of ALS, 19 cases of PD and 18 cases of PMR were recorded, with mean ages of onset of 33, 43, and 26, respectively, in a small affected population of only about 7000. The ecology, culture, and diet of the remote, primitive ALS- and PD-affected people are indistinguishable from that of their unaffected neighbors, except for a remarkable deficiency of calcium and magnesium in their soil and drinking water. The distribution of affected and nonaffected villages indicates that communicable infectious or genetic etiology is unlikely. As a result of the isolation and primitive technology, domestic animals (except dogs and pigs) were not found among the Auyu and Jakai, and no manufactured products (including metals, ceramics, textiles, petrochemicals, medicines, food additives, condiments, paints, dyes, or solvents) were available to them.

Residual impairments and work status 15 years after penetrating head injury: report from the Vietnam Head Injury Study.

We investigated the relationship of neurologic, neuropsychological, and social interaction impairments to the work status of a large sample of penetrating head-injured patients wounded some 15 years earlier during combat in Vietnam. Extensive standardized testing of neurologic, neuropsychological, and social functioning was done at follow-up on each head-injured patient (N = 520), as well as on a sample of uninjured controls (N = 85). Fifty-six percent of the head-injured patients were working at follow-up compared with 82% of the uninjured controls. Seven systematically defined impairments proved to be most correlated with work status. These were post-traumatic epilepsy, paresis, visual field loss, verbal memory loss, visual memory loss, psychological problems, and violent behavior. These disabilities had a cumulative and nearly equipotent effect upon the likelihood of work. We suggest that a simple summed score of the number of these seven disabilities can yield a residual "disability score" which may prove to be a practical tool for assessing the likelihood of return to work for patients in this population and perhaps in other brain-injured populations. These findings may also help to focus rehabilitation efforts on those disabilities most likely to affect return to work.

Frontal lobe injuries, violence, and aggression: a report of the Vietnam Head Injury Study.

Knowledge stored in the human prefrontal cortex may exert control over more primitive behavioral reactions to environmental provocation. Therefore, following frontal lobe lesions, patients are more likely to use physical intimidation or verbal threats in potential or actual confrontational situations. To test this hypothesis, we examined the relationship between frontal lobe lesions and the presence of aggressive and violent behavior. Fifty-seven normal controls and 279 veterans, matched for age, education, and time in Vietnam, who had suffered penetrating head injuries during their service in Vietnam, were studied. Family observations and self-reports were collected using scales and questionnaires that assessed a range of aggressive and violent attitudes and behavior. Two Aggression/Violence Scale scores, based on observer ratings, were constructed. The results indicated that patients with frontal ventromedial lesions consistently demonstrated Aggression/Violence Scale scores significantly higher than controls and patients with lesions in other brain areas. Higher Aggression/Violence Scale scores were generally associated with verbal confrontations rather than physical assaults, which were less frequently reported. The presence of aggressive and violent behaviors was not associated with the total size of the lesion nor whether the patient had seizures, but was associated with a disruption of family activities. These findings support the hypothesis that ventromedial frontal lobe lesions increase the risk of aggressive and violent behavior.

Consciousness and amnesia after penetrating head injury: neurology and anatomy.

Among 342 men who survived severe penetrating brain wounds, only 15% had prolonged unconsciousness and 53% had no or momentary unconsciousness after injury, emphasizing the focal nature of these wounds. The left (or language-dominant) hemisphere was dominant for the "wakefulness" component of consciousness. The areas most associated with unconsciousness included the posterior limb of the left internal capsule, left basal forebrain, midbrain, and hypothalamus. Left dominance was not seen for posttraumatic amnesia after elimination of the wakefulness variable, suggesting that wakefulness may be linked to the role of the left hemisphere in verbal memory.

Epilepsy after penetrating head injury. I. Clinical correlates: a report of the Vietnam Head Injury Study.

Of 421 veterans who had penetrating brain wounds in Vietnam 15 years ago, 53% had posttraumatic epilepsy, and one-half of those still had seizures 15 years after injury. The relative risk of developing epilepsy dropped from about 580 times higher than the general age-matched population in the first year to 25 times higher after 10 years. Patients with focal neurologic signs or large lesions had increased risk of epilepsy, and site of the lesion may have been more important than size in determining occurrence. Family history of epilepsy or preinjury intelligence had no effect on seizure occurrence. Seizure frequency in the first year predicted future severity of seizures. Phenytoin therapy in the first year after injury did not prevent later seizures.

Penetrating war injuries of the basal forebrain: neurology and cognition.

We compared the neurologic and cognitive performance of 15 young veterans who suffered unilateral penetrating missile wounds to the basal forebrain 15 years ago in the Vietnam War with uninjured controls and patients with lesions elsewhere in the brain. The subjects performed worse on tests of episodic memory, reasoning, and arithmetic and had more prolonged unconsciousness after injury; but their performance usually compared favorably with that of uninjured controls on tests of intelligence, attention, and language and was not consistent with that of a demented patient. The data suggest that the basal forebrain is functionally related to the reticular formation and to the basal forebrain is functionally related to the reticular formation and to the limbic-hippocampal memory system.

Preliminary trial of poly ICLC in chronic progressive multiple sclerosis.

Eighteen patients with chronic progressive multiple sclerosis (MS) were treated in an open preliminary trial of the interferon inducer and immune modulator, poly ICLC. All patients produced substantial interferon levels and experienced acute side effects, including fever and transient worsening of neurologic symptoms. Of nine patients with rapid neurologic deterioration at the time of entry into the study, only three had disease progression during treatment. We conclude that poly ICLC can be administered safely to MS patients, and that a controlled trial will be necessary to determine efficacy.

A longitudinal study of T1 hypointense lesions in relapsing MS: MSCRG trial of interferon beta-1a. Multiple Sclerosis Collaborative Research Group.

BACKGROUND: T1 hypointense lesions (T1 black holes) are focal areas of relatively severe CNS tissue damage detected by MRI in patients with MS. OBJECTIVE: To determine the natural history of T1 hypointense lesions in relapsing MS and the utility of T1 hypointense lesions as outcome measures in MS clinical trials. METHODS: MR studies were from the Multiple Sclerosis Collaborative Research Group trial. Longitudinal results are reported in 80 placebo- and 80 interferon beta-1a (IFNbeta-1a)-treated patients with mild to moderate disability relapsing-remitting MS. RESULTS: There was a small but significant correlation between T1 hypointense lesion volume and disability at baseline and on trial (r = 0.22, r = 0.28). In placebo patients there was a 29.2% increase in the mean volume of T1 hypointense lesions (median 124.5 mm3) over 2 years (p < 0.001 for change from baseline), as compared to an 11.8% increase (median 40 mm3) in the IFNbeta-1a-treated patients (change from baseline not significant). These treatment group comparisons did not quite reach significance. The most significant contributor to change in T1 hypointense lesions was the baseline number of enhancing lesions (model r2 = 0.554). Placebo patients with more active disease, defined by enhancing lesions at baseline, were the only group to show a significant increase in T1 hypointense lesion volume from baseline. CONCLUSION: The development of T1 hypointense lesions is strongly influenced by prior inflammatory disease activity, as indicated by enhancing lesions. These results suggest that treatment with once weekly IM IFNbeta-1a (30 mcg) slows the 2-year accumulation of these lesions in the brain.

A longitudinal study of brain atrophy in relapsing multiple sclerosis. The Multiple Sclerosis Collaborative Research Group (MSCRG).

OBJECTIVE: To determine if progressive brain atrophy could be detected over 1- and 2-year intervals in relapsing MS, based on annual MR studies from the Multiple Sclerosis Collaborative Research Group (MSCRG) trial of interferon beta-1a (Avonex). METHODS: All subjects had mild to moderate disability, with baseline expanded disability status scores ranging from 1.0 to 3.5, and at least two relapses in the 3 years before study entry. Atrophy measures included third and lateral ventricle width, brain width, and corpus callosum area. RESULTS: Significant increases were detected in third ventricle width at year 2 and lateral ventricle width at 1 and 2 years. Significant decreases in corpus callosum area and brain width were also observed at 1 and 2 years. Multiple regression analyses suggested that the number of gadolinium-enhancing lesions at baseline was the single significant contributor to change in third ventricle width. Atrophy over 1 and 2 years as indicated by enlargement of the third and lateral ventricle and shrinkage of the corpus callosum was greater for patients entering the trial with enhancing lesions. Greater disability increments over 1 and 2 years were associated with more severe third ventricle enlargement. CONCLUSION: In patients with relapsing MS and only mild to moderate disability, significant cerebral atrophy is already developing that can be measured over periods of only 1 to 2 years. The course of cerebral atrophy in MS appears to be influenced by prior inflammatory disease activity as indicated by the presence of enhancing lesions. Brain atrophy measures are important markers of MS disease progression because they likely reflect destructive and irreversible pathologic processes.

Incidence and significance of neutralizing antibodies to interferon beta-1a in multiple sclerosis. Multiple Sclerosis Collaborative Research Group (MSCRG)

BACKGROUND: Interferon beta is an effective treatment for relapsing multiple sclerosis (MS). As with other protein drugs, neutralizing antibodies (NAB) can develop that reduce the effectiveness of treatment. OBJECTIVES: To determine the incidence and biological significance of NAB to interferon beta-la (IFN-beta-1a; Avonex; Biogen, Cambridge, MA) in MS patients. METHODS: A two-step assay for NAB to IFN-beta-1a was developed and used to assay serum samples from participants in the phase III clinical trial of IFN-beta-1a, and from patients in an ongoing open-label study of IFN-beta-1a. The biological significance of NAB to IFN-beta-1a was determined by relating the NAB assay result to in vivo induction of the IFN-inducible molecules neopterin and beta-2 microglobulin, and the clinical significance was determined by comparing clinical and MRI measures of disease activity after 2 years of IFN-beta-1a therapy in patients who were NAB+ and NAB-. The incidence of NAB was compared in MS patients who had used only IFN-beta-1a with the incidence in MS patients who had used only IFN-beta-1b. RESULTS: In patients in the open-label study, development of NAB to IFN-beta-1a resulted in a titer-dependent reduction in neopterin induction after interferon injections. In patients in the phase III study, development of NAB was associated with a reduction in beta-2 microglobulin induction. In the phase III study, a trend toward reduced benefit of IFN-beta-1a on MRI activity in NAB+ versus NAB- patients was observed. The incidence of NAB to IFN-beta-1a in the open-label study was approximately 5% over 24 months of treatment of IFN-beta-1a therapy, but was four- to sixfold higher using the same assay for patients exposed only to IFN-beta-1b for a similar duration. There were no clinical, MRI, or CSF characteristics that were predictive of which patients would develop NAB. CONCLUSIONS: NAB directed against IFN-beta have in vivo biological consequences in patients with MS. The frequency with which MS patients develop NAB against IFN-beta is significantly greater with IFN-beta-1b therapy compared with IFN-beta-1a therapy. Treatment decisions in MS patients treated with IFN-beta should take into account development of NAB.

Impact of interferon beta-1a on neurologic disability in relapsing multiple sclerosis. The Multiple Sclerosis Collaborative Research Group (MSCRG).

BACKGROUND AND OBJECTIVE: A phase III double-blind, placebo-controlled clinical trial demonstrated that interferon beta-1a (IFN beta-1a) (Avonex, Biogen) significantly delayed progression of disability in relapsing MS patients. The primary clinical outcome was time from study entry until disability progression, defined as > or = 1.0 point worsening from baseline Kurtzke Expanded Disability Status Scale (EDSS) score persisting for at least two consecutive scheduled visits separated by 6 months. The objective of this study was to examine the magnitude of benefit on EDSS and its clinical significance. METHODS: Post hoc analyses related to disability outcomes using data collected during the double-blind, placebo-controlled phase III clinical trial. RESULTS: (1) Clinical efficacy related to disability did not depend on the definition of disability progression. A significant benefit in favor of IFN beta-1a was observed when > or = 2.0 point worsening from baseline EDSS was required or when worsening was required to persist for > or = 1.0 year. (2) Placebo recipients who reached the primary clinical outcome worsened by a larger amount from baseline EDSS than did IFN beta-1a recipients who reached the primary study outcome. (3) Significantly fewer IFN beta-1a recipients progressed to EDSS milestones of 4.0 (relatively severe impairment) or 6.0 (unilateral assistance needed to walk). (4) Cox proportional hazards models demonstrated that the only baseline characteristic strongly correlated with longer time to disability progression was IFN beta-1a treatment. CONCLUSIONS: The primary clinical outcome for the IFN beta-1a clinical trial underestimated clinical benefits of treatment. Results in this report demonstrate that IFN beta-1a treatment is associated with robust, clinically important beneficial effects on disability progression in relapsing MS patients.

Cerebrospinal fluid abnormalities in a phase III trial of Avonex (IFNbeta-1a) for relapsing multiple sclerosis. The Multiple Sclerosis Collaborative Research Group.

BACKGROUND AND OBJECTIVE: This report provides results of CSF analyses done in a subset of relapsing remitting MS patients participating in a placebo-controlled, double-blind, phase III clinical trial of IFNbeta-Studies supported by the National Multiple Sclerosis Society (grants RG2019, RG2827),a (Avonex , Biogen). The clinical trial demonstrated that IFNbeta-1a treatment resulted in significantly reduced disability progression, annual relapse rate, and new brain lesions visualized by cranial magnetic resonance imaging. The objectives of the current study were to determine: (a) whether CSF abnormalities in MS patients correlated with disease or MRI characteristics, and (b) effects of IFNbeta-1a therapy on these CSF abnormalities. METHODS: CSF was analyzed from 262 (87%) of the 301 study subjects at entry into the clinical trial, and a second CSF sample was analyzed from 137 of these 262 subjects after 2 years of therapy. CSF cell counts, oligoclonal bands (OCB), IgG index, and free kappa light chains were measured using standard assays. Baseline CSF results were compared with demographic, disease, and MRI parameters. Differences in on-study relapse rate, gadolinium enhancement, and EDSS change according to baseline CSF status was used to determine the predictive value of CSF for subsequent clinical and MRI disease activity. Change in CSF parameters after 104 weeks were used to determine the effects of treatment. RESULTS: (1) At study baseline, 37% of the subjects had abnormal CSF WBC counts, 61% had abnormal levels of CSF free kappa light chains, 84% had abnormal IgG index values, and 90% were positive for OCB. (2) Baseline IgG index, kappa light chains, and OCB showed weakly positive, statistically significant correlations with Gd-enhanced lesion volume and T2 lesion volume. WBC showed a statistically significant correlation with Gd-enhancing lesion volume but was uncorrelated with T2 lesion volume. (3) There was an associated between baseline CSF WBC counts and on-study clinical and MRI disease activity in placebo recipients. (4) IFNbeta-1a treatment resulted in significantly reduced CSF WBC counts, but there was no treatment-related change in CSF IgG index, kappa light chains, or OCB, which remained relatively stable over time in both patient groups. CONCLUSIONS: The current study documents significant reductions in CSF WBC counts in patients treated with IFNbeta-1a for 104 weeks. This finding is considered relevant to the therapeutic response, since CSF WBC counts were found to be positively correlated with subsequent clinical and MRI disease activity in placebo-treated relapsing MS patients.

Genotoxic monitoring of workers at a hazardous waste disposal site in Mexico.

Chromosomal aberration and sister chromatid exchange (SCE) frequencies were determined in lymphocytes cultured from 12 high-risk individuals working at a landfill for hazardous waste disposal. Cell proliferation kinetics (CPK) was also determined. Compared with 7 control individuals, no effects were observed with respect to SCE nor on CPK. However, the workers exhibited significantly higher frequencies of chromatid and chromosomal deletions, the magnitude of which was related with exposure time. This study suggests that when high-risk exposure is suspected, determining biomarkers of genotoxic damage (e.g., chromosomal aberrations), is useful for risk assessments.