Serum and cerebrospinal fluid urate levels in synucleinopathies versus tauopathies

BACKGROUND

Low levels of serum urate are associated with a higher risk of Parkinson's disease (PD). Higher serum and cerebrospinal fluid (CSF) urate levels are associated with slower rates of clinical decline in PD and in multiple system atrophy (MSA).

AIMS

To compare CSF and blood urate levels in healthy controls, patients with synucleinopathies and with tauopathies.

METHODS

We investigated urate levels in serum and CSF from 18 healthy controls, 19 patients with synucleinopathies (six patients with PD and 13 with MSA), and 24 patients with tauopathies (18 with progressive supranuclear palsy and six with corticobasal degeneration). None of the patients were treated with dopaminergic medications.

RESULTS

No significant differences were seen when comparing serum and CSF urate levels from controls across the parkinsonian diagnostic groups. However, in men, serum urate levels were significantly lower in the synucleinopathy group compared with the tauopathy group (P = 0.046), although with a broad overlap.

CONCLUSION

Our study suggests that urate levels might provide new insights into the potential pathophysiological mechanisms underlying Parkinsonism and thereby contribute to the future management of these disorders.

Interim analysis of long-term intraduodenal levodopa infusion in advanced Parkinson disease

BACKGROUND

This interim 12-month analysis is a part of an open-label, observational, prospective study on health outcomes and cost impact of levodopa/carbidopa intestinal gel (LCIG, Duodopa) in Parkinson disease (PD). The specific aim was to investigate clinical and health-related quality of life (HRQoL) effects in routine care.

METHODS

Unified PD rating scale (UPDRS) was the primary efficacy measurement. PD QoL questionnaire 39 (PDQ-39) assessed HRQoL. Subjects were assessed at baseline, ≥3 months after surgery, and then every 3 months.

RESULTS

Twenty-seven treatment-naïve subjects when started with LCIG showed a decrease in UPDRS score that was statistically significant throughout the year: UPDRS total score (mean ± SD), baseline = 52.1 ± 16.1, N = 27, month 0 (first visit; at least 3 months after permanent LCIG) = 43.1 ± 16.7, N = 27, P = 0.003; month 12 = 42.5 ± 22.6, n = 25, P = 0.017. PDQ-39 results also showed a tendency for improvement: PDQ-39 (mean ± SD), baseline = 33.6 ± 10.8, N = 27, month 0 = 27.1 ± 11.8, N = 27, P = 0.001; 12 months = 28.8 ± 12.8, n = 23, P = 0.126.

CONCLUSIONS

LCIG provides functional improvement beginning at first visit that is sustained for 12 months.

Anal sphincter electromyography in patients with newly diagnosed idiopathic parkinsonism

OBJECTIVES

The differential diagnosis of patients with idiopathic parkinsonism is difficult, especially early in the course of the disease. External anal sphincter electromyography (EAS-EMG) has been reported to be of value in the differential diagnosis between Parkinson's disease (PD) and multiple system atrophy (MSA). Patients with MSA are reported to have pathological EAS-EMG and patients with PD are reported to have significantly less pathological EAS-EMG results. Comparisons between patients with parkinsonian disorders have usually been made many years into the disease, and thus it is largely unknown if the results of EAS-EMG can be used to distinguish the different diagnoses in the early phase of the disease.

MATERIALS AND METHODS

We investigated 148 newly diagnosed patients with idiopathic parkinsonism from a population-based incidence cohort (100 definite PD, 21 probable PD, 16 MSA, 11 progressive supranuclear palsy, and 40 controls) with EAS-EMG within 3 months of their first visit and, in the majority of patients, before start of treatment with dopaminergic drugs. The clinical diagnoses were made using established clinical diagnostic criteria after a median follow-up of 3 years.

RESULTS

All patient groups had more pathological EAS-EMG results than controls. No EAS-EMG differences were found between the patient groups, especially not between PD and MSA.

CONCLUSIONS

External anal sphincter electromyography examination cannot separate the different parkinsonian subgroups from each other in early course of the diseases.

Light subunit of neurofilament triplet protein in the cerebrospinal fluid after subthalamic nucleus stimulation for Parkinson's disease

OBJECTIVES

Cerebrospinal fluid (CSF) levels of neurofilament triplet protein (NFL), a non-specific marker of neuronal damage, are normal in Parkinson's disease (PD) but increased after brain trauma and in several neurological disorders. Using longitudinal CSF-NFL measurements as an indicator of neuronal damage, this study investigated the impact of deep brain stimulation (DBS) of the subthalamic nucleus (STN) on the brain, directly following the surgical intervention and in chronically treated patients with PD.

MATERIALS AND METHODS

CSF-NFL levels were measured consecutively in eight patients with PD before and after STN-DBS treatment.

RESULTS

CSF-NFL levels were normal prior to STN-DBS and increased sharply during the first 2 weeks post-operatively, but normalized after 12 months or more.

CONCLUSION

The STN-DBS procedure leads to an acute but limited neuronal damage, as expected. However, normal CSF-NFL levels at 12 months post-operatively and beyond suggest the absence of any long-term neuronal damage caused by long-term STN-DBS stimulation.

A new automated implementation of the Posturo-Locomotion-Manual (PLM) method for movement analysis in patients with parkinson's disease

OBJECTIVE

The Posturo-Locomotion-Manual (PLM) test, which uses an optoelectronic laboratory system, has here been further developed into an automated, more user-friendly, standardized tool for movement analysis named the QbTestMotus. This paper compares the accuracy of QbTestMotus to the PLM test, in particular the automated data analysis.

METHODS

Both QbTestMotus and the PLM recorded data simultaneously from the same 61 patients. The correlation coefficients of movement time (MT), postural time (P), locomotion time (L), and manual time (M) were calculated between the systems. The absolute differences between the result parameters for each patient were also studied. Finally, the differences in MT between the systems were compared with the positive responses in the levodopa (L-dopa) challenges as measured in the PLM test for 11 patients.

RESULTS

The comparisons in all the 61 patients showed high correlation coefficients for all four parameters. The absolute differences between the parameters were small and had small standard deviations, and the decreases in MT because of L-dopa in the positive L-dopa responders were much larger than the absolute difference between the systems.

CONCLUSION

The PLM test and QbTestMotus are equivalent along all parameters, thus indicating that the test quality is equivalent between the PLM test and the automated QbTestMotus system.

Autonomic innervation in multiple system atrophy and pure autonomic failure

BACKGROUND

Pure autonomic failure (PAF) and multiple system atrophy (MSA) are both characterised by chronic dysautonomia although presenting different disability and prognosis. Skin autonomic function evaluation by indirect tests has revealed conflicting results in these disorders. Here, the authors report the first direct analysis of skin sympathetic fibres including structure and function in PAF and MSA to ascertain different underlying autonomic lesion sites which may help differentiate between the two conditions.

METHODS

The authors studied eight patients with probable MSA (mean age 60±5 years) and nine patients fulfilling diagnostic criteria for PAF (64±8 years). They underwent head-up tilt test (HUTT), extensive microneurographic search for muscle and skin sympathetic nerve activities from peroneal nerve and punch skin biopsies from finger, thigh and leg to evaluate cholinergic and adrenergic autonomic dermal annexes innervation graded by a semiquantitative score presenting a high level of reliability.

RESULTS

MSA and PAF patients presented a comparable neurogenic orthostatic hypotension during HUTT and high failure rate of microneurographic trials to record sympathetic nerve activity, suggesting a similar extent of chronic dysautonomia. In contrast, they presented different skin autonomic innervation in the immunofluorescence analysis. MSA patients showed a generally preserved skin autonomic innervation with a significantly higher score than PAF patients showing a marked postganglionic sympathetic denervation. In MSA patients with a long disease duration, morphological abnormalities and/or a slightly decreased autonomic score could be found in the leg reflecting a mild postganglionic involvement.

CONCLUSION

Autonomic innervation study of skin annexes is a reliable method which may help differentiate MSA from PAF.

Comparison of apomorphine and levodopa infusions in four patients with Parkinson's disease with symptom fluctuations

BACKGROUND

Motor fluctuations in patients with advanced Parkinson's disease may be successfully treated with subcutaneous apomorphine infusion or intraduodenal levodopa/carbidopa infusion. No comparative trials of these two alternatives were performed.

AIMS OF THE STUDY

We present a subanalysis from a randomized crossover clinical trial where levodopa infusion as monotherapy was compared with any other combination of pharmacotherapy in fluctuating patients. Four patients used apomorphine infusion and oral levodopa in the comparator arm. The results of these four patients are presented in detail.

METHODS

The duration of the trial was 3 + 3 weeks. Patients were video-recorded half-hourly on two non-consecutive days of both treatment arms. Blinded video ratings were used. Patient self-assessments of motor function and quality-of-life (QoL) parameters were captured using an electronic diary.

RESULTS

Ratings in moderate to severe "off" state ranged 0-44% on apomorphine infusion and 0-6% on levodopa infusion. Moderate to severe dyskinesias were not recorded in any of the treatments. QoL was reported to be improved in all patients on duodenal levodopa infusion.

CONCLUSIONS

Monotherapy with duodenal infusion of levodopa was more efficacious and brought greater QoL than combination therapy with apomorphine infusion in these fluctuating patients.

Cytochrome P450 2E1 gene polymorphisms/haplotypes and Parkinson's disease in a Swedish population

Cytochrome P450 2E1 (CYP2E1), which inter alia is located in dopamine containing neurons in the substantia nigra, has been hypothesized to be of importance for the pathophysiology of Parkinson's disease (PD), either by its production of reactive oxygen species (ROS) or by its capability to detoxify putative neurotoxins. Numerous polymorphisms in the coding and non-coding regions of the gene for this enzyme have been reported. Different variants may account for inter-individual differences in the activity of the enzyme or production of ROS. In this study, the CYP2E1 gene was examined in a control population (n = 272) and a population with PD (n = 347), using a tag-single nucleotide polymorphism (tSNP) approach founded on HapMap Data. Six tSNPs were used in the analysis and haplotype block data were obtained. In case of significance, the SNP was further examined regarding early/late age of disease onset and presence of relatives with PD. We found an association between allele and genotype frequencies of the C/G polymorphism at intron 7 (rs2070676) of this gene and PD (P value of 0.026 and 0.027, respectively). Furthermore, analysis of the rs2070676 polymorphism in subgroups of patients with age of disease onset higher than 50 years and those not having a relative with PD also demonstrated a significant difference with controls. This was seen in both genotype (corresponding to P value = 0.039 and 0.032) and allele (P = 0.027 and 0.017 respectively) frequency. As a representative of many polymorphisms or in possible linkage disequilibrium with other functional variants, it is possible that rs2070676 could influence the regulation of the enzyme. In conclusion, our results display an association between the rs2070676 polymorphism and PD. Additional investigations are needed to elucidate the importance of this polymorphism for the activity of CYP2E1 and PD susceptibility.

Minimized weight gain between hemodialysis contributes to a reduced risk of death

The risk of death is higher in dialysis patients compared to age matched healthy subjects, the main reason being cardiovascular. This prospective study investigated if the extent of ultrafiltration was of importance for the outcome.

MATERIAL AND METHODS

88 hemodialysis patients were included and followed prospectively. The outcome was registered in regard to death, acute myocardial infarction or coronary vascular intervention. The extent of ultrafiltration needed at dialysis was calculated as a mean during the observation period as were other variables. The mean extent of ultrafiltration was compared for patients who had survived without end-points (group 1, n=53) versus those who reached any end-point during the period (group 2, n=35).

RESULTS

In total, 40% of the patients reached end-point during the observation period. There was no difference at baseline between the groups in regard to age, prevalence of diabetes mellitus or history of previous cardiovascular disease, KT/V, residual renal function ultrafiltration need, C-reactive protein, s-albumin, cholesterol, LDL-cholesterol, HDL-cholesterol, appetite or wellbeing, while triglyceride was lower in group 2 (p=0.035). The observation period for group 1 was at a mean 24.7 months (SD13.1) and for those in group 2 at a mean 13.8 (+/-11.7 months, p<0.001). Patients representing group 1 at 24 and 30 months had less need of ultrafiltration than those in group 2. Thus, the need of ultrafiltration was about 27% lower at 24 months (for 29 persons in group 1: 3.63+/-1.93 weight% versus 4.97+/-1.70 weight% for 9 patients from group 2, p=0.046) and 46% at 30 months (for 18 from group 1: 3.48+/-1.95 versus 6.45+/-1.55 for 3 from group 2, p=0.030). C-reactive protein did not differ significantly between the groups during the period.

CONCLUSION

After a prolonged period of 24 months the extent of ultrafiltration need seems to be important for the outcome of the patients. Thereby those with higher need of ultrafiltration had worse prognosis. It seems important to motivate patients to reduce the extent of fluid intake between dialysis to prolong survival.

Inadvertent malposition of a transvenous pacing lead in the left ventricle

We report the case of inadvertent malpositioning of a pacemaker lead in the left ventricle. The lead went through an open foramen ovale from the right to the left atrium and through the mitral valve into the left ventricle. After a review of the literature, we decided to anticoagulate the patient and leave the electrode in place. During a follow-up period of 16 months, there were no clinical complications.

Development of an spFRET method to measure structure changes in ion exchange proteins

AIM

Understanding the mechanism of tightly coupled ion exchange proteins, important effectors of cell volume regulation and other physiologically important transport processes requires means to observe dynamic changes in structure during the transport cycle. As a step towards this goal, we have applied single-pair fluorescence resonance energy transfer to a monomeric bacterial oxalate-formate exchanger (OxlT).

METHODS

A His-9 tagged OxlT mutant containing two cysteines at positions 17 and 224 was labelled with cyanine dye maleimides (Cy3 donor and Cy5 acceptor) and attached to glass coverslips for measurements of donor and acceptor emission from single molecules, as described (P. Pal et al. Biophys J89, L11, 2005).

RESULTS

Time-series data from 20 spots containing donor and acceptor provided evidence for single-pair energy transfer. From the efficiency of energy transfer, the mean donor-acceptor distance was determined to be 44.2 A. Considering the size of the probes, this is in good agreement with the Calpha distance of 39.6 A for the corresponding sites found in the OxlT structural (homology) model (Q. Yang et al. Proc Natl Acad Sci102, 8513, 2005).

CONCLUSION

These results demonstrate the feasibility of single-pair fluorescence resonance energy transfer to measure distances between known sites in single OxlT molecules. This technique provides a potential means to test models for transport-related conformational changes, as well as to detect real-time structure alterations during the catalytic transport cycle.

Safety and efficacy of atorvastatin in patients with severe renal dysfunction

OBJECTIVE

To investigate the efficacy and safety of a daily dose of 10 mg of atorvastatin in patients with chronic kidney disease (CKD) stages 4 and 5 and a glomerular filtration rate of <30 ml/min.

MATERIAL AND METHODS

This was an open, prospective, randomized study. A total of 143 patients were included: 73 were controls and 70 were prescribed 10 mg/day of atorvastatin. As efficacy variables, total cholesterol, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol and triglyceride levels were determined at the start of the study and at 1, 3, 6, 12, 18, 24, 30 and 36 months.

RESULTS

The follow-up period was a mean of 20+/-14.4 months (range 1-36 months) for those on atorvastatin versus 22+/-12.7 months (range 0.5-36 months) for the controls. Compared with baseline values, patients treated with atorvastatin had significantly lower concentrations of total cholesterol at Month 36 (5.8 vs 4.4 mmol/l; -23%; p<0.001), of LDL cholesterol at Month 36 (3.6 vs 2.2 mmol/l; -35%; p<0.001) and of triglycerides at Months 24 (2.5 vs 1.9 mmol/l) and 36 (2.5 vs 1.8 mmol/l). The controls had significantly reduced levels of total cholesterol at Month 36 (p<0.21) and of LDL cholesterol at Months 30 and 36. Compared with the controls, the atorvastatin group had lower levels of total cholesterol and LDL cholesterol at Months 1-30. Fifteen patients (21%) stopped taking their medication as they could not tolerate the side-effects, the most frequent complaints being gastrointestinal discomfort and headache.

CONCLUSION

Although the medication caused no severe adverse events, we recommend caution when using atorvastatin for severe CKD patients until further evidence of its safety and efficacy is verified.

Duodenal levodopa infusion monotherapy vs oral polypharmacy in advanced Parkinson disease

OBJECTIVES

To compare daytime intraduodenal levodopa/carbidopa infusion as monotherapy with individually optimized conventional combination therapies in patients with advanced Parkinson disease (PD) for motor fluctuations and quality of life (QoL).

METHODS

Twenty-four patients with motor fluctuations and dyskinesia were studied in a randomized crossover design to compare individualized conventional treatment and intraduodenal infusion of a levodopa/carbidopa gel for 3 + 3 weeks. Video scoring of motor function was assessed by blinded assessors on a global Treatment Response Scale from -3 to 0 to +3 (from severe "off" to "on" to "on" with severe dyskinesia). Patient self-assessment of motor performance and QoL was done using an electronic diary.

RESULTS

Median percentage of ratings in a functional "on" interval (-1 to +1) was increased from 81 to 100% by infusion therapy (p < 0.01). This improvement was accompanied by a decrease in "off" state (p < 0.01) and no increase in dyskinesia. Median Unified Parkinson's Disease Rating Scale score decreased from 53 to 35 in favor of infusion (p < 0.05). QoL was improved, using the two instruments: Parkinson's Disease Questionnaire-39 and 15D Quality of Life Instrument (p < 0.01). Adverse events were similar for both treatment strategies.

CONCLUSIONS

Continuous intraduodenal infusion of the levodopa/carbidopa enteral gel as monotherapy is safe and clinically superior to a number of individually optimized combinations of conventional oral and subcutaneous medications in patients with motor fluctuations. Intraduodenal infusion of levodopa offers an important alternative in treating patients with advanced Parkinson disease.

Association between the estrogen receptor beta gene and age of onset of Parkinson's disease

The purpose of this study was to investigate the potential contribution of genetic variants in the estrogen receptor beta gene to the aetiology of Parkinson's disease (PD). Several lines of evidence from human and animal studies suggest a protective role for estrogen in PD. Recently the estrogen receptor beta subtype was reported to be an important mediator of estrogen actions in the nigrostriatal dopamine system. Two single nucleotide polymorphisms at position 1730 and 1082 in the ER beta gene were genotyped, using pyrosequencing, in 260 patients with PD and 308 controls recruited from the Swedish population. Neither of the two estrogen receptor beta polymorphisms was associated with an increased risk for PD. However, the G allele of the A1730G polymorphism was more frequent in patients with an early age of onset than in patients with a late age of onset of PD (P = 0.006). Patients carrying the GG genotype had an odds ratio of 2.2 for having an early onset of PD compared to non-carriers. In conclusion, our results indicate that genetic variation in the estrogen receptor beta gene may influence the age of onset of PD.

CSF-neurofilament and levodopa tests combined with discriminant analysis may contribute to the differential diagnosis of Parkinsonian syndromes

The differentiation between Parkinson's disease (PD), progressive supranuclear palsy (PSP) and multiple system atrophy (MSA) is important for prognostic and therapeutic purposes. In order to evaluate the diagnostic capability of two tests reflecting these items, patients fulfilling strict clinical criteria for PD (n=35), MSA (n=36) and PSP (n=14), were consecutively included. An analysis of neurofilament protein (NFL), a marker of axonal degeneration in the cerebrospinal fluid (CSF) and a levodopa test, recorded with optoelectronic technique were performed. Using discriminant analyses, the test's abilities to predict the clinical PD or non-PD (MSA and PSP) diagnoses were compared. Whereas the CSF-NFL and levodopa tests predicted 79 and 85% correct diagnoses respectively, the combined test predicted 90% correct diagnoses. We conclude that the CSF-NFL and levodopa tests provide detailed information of clinical variables on which the clinical diagnostic criteria are based. As they are pathologically unrelated, the diagnostic precision increases compared to clinical diagnoses when they are combined.

Cardiovascular reflex testing contributes to clinical evaluation and differential diagnosis of Parkinsonian syndromes

The differentiation between Parkinson's disease (PD), progressive supranuclear palsy (PSP), and multiple system atrophy (MSA) may be difficult but is important for prognostic and therapeutic purposes. Varying degrees of autonomic failure have been described in PD and MSA, whereas its involvement in PSP remains controversial. The aim of this study was to investigate autonomic function in patients fulfilling strict clinical diagnostic criteria for the disorders above, to evaluate the diagnostic capacity of laboratory autonomic tests. The study group was consecutively recruited among patients referred to a movement disorder unit. Thirty-four patients with PD, 15 patients with PSP, and 47 patients with MSA were compared with 18 healthy age-matched controls. Autonomic tests included analysis of heart rate variability (HRV) in temporal domain, at rest and during forced respiration, as well as blood pressure (BP) changes during 75 degrees head-up tilt. HRV did not differ between groups during quiet breathing but was significantly reduced during forced respiration in MSA (P < 0.01), while PD and PSP groups did not differ from controls. Hypotensive responses during orthostatic provocation were seen in PD (P < 0.01) and MSA (P < 0.001), whereas BP remained stable in most PSP patients, not differing from the healthy control group. On an individual basis, decreased HRV and severe hypotensive responses were seen in MSA patients regardless of age and disease duration, whereas PD patients showed this combination only at high age and long duration. In PSP, only a few cases with decreased HRV and limited hypotensive responses were found. We conclude that cardiovascular reflex tests can supplement the clinical differentiation of Parkinsonian syndromes.

Mammary tumours in Sprague-Dawley rats after initiation with DMBA followed by exposure to 50 Hz electromagnetic fields in a promotional scheme

In order to test whether a transient-producing intermittent magnetic field (MF) acts as a promoter in rat mammary tumour development, a study of a 50 Hz sinusoidal MF with flux densities of 0.25 and 0.5 mT was performed on female Sprague-Dawley rats. A single administration of 7 mg of 7,12-dimethyl-benz[a]anthracene (DMBA) was given by gavage to 52-day-old animals. After 1 week, exposure to an intermittent (15 s on/15 s off) transient-associated magnetic field was started. MF exposure was performed for 19 or 21 h per day up to 25 weeks, when the study was terminated. Twice a week a careful examination with palpation for tumours was done. Tumour incidence, the number of tumours per animal, tumour volume and tumour weight were recorded. A total of 70% of MF-exposed animals developed tumours. For animals exposed to DMBA alone the correspondent figure was 71.7%. No statistical differences were seen either for tumour-bearing animals or for the total number of tumours. A slightly larger total tumour weight and tumour volume was seen for animals exposed to 0.25 mT MF. These differences were not statistically significant.

Increased cerebrospinal fluid levels of neurofilament protein in progressive supranuclear palsy and multiple-system atrophy compared with Parkinson's disease

More reliable tools are needed for the differentiation of Parkinson's disease (PD) from other parkinsonian disorders. The neurofilament protein (NFL) and the glial fibrillary acidic protein (GFAP) are main structural proteins of axons and fibrillary astroglial cells. By using enzyme-linked immunosorbent assays, these proteins were quantified in the cerebrospinal fluid (CSF) of 49 patients referred to the Department of Neurology for diagnostic consideration or treatment of parkinsonism of different etiologies. All patients were first diagnostically evaluated by strict clinical criteria. The procedure included a neurologic and neuro-ophthalmologic examination as well as computed tomography or magnetic resonance imaging. These were performed independently and in advance of the CSF analysis. A total of 19 patients were diagnosed as having PD, 12 had progressive supranuclear palsy (PSP), and 10 had multiple-system atrophy (MSA). Eight were diagnosed as having other diseases, such as arteriosclerotic parkinsonism and undefined parkinsonian syndromes. The content of NFL was significantly higher both in the PSP group (p < 0.001) and in the MSA group (p < 0.0001) compared with the PD group. The high values of NFL indicate an ongoing neuronal degeneration affecting mainly the axonal compartment in the PSP and MSA groups, whereas there was no difference in glial involvement as measured by GFAP in the PD, PSP, and MSA groups. There was a relation between high CSF levels of NFL in the various patient groups and the occurrence of pyramidal symptoms (p < 0.001), possibly reflecting the axonal damage to the corticospinal tract. Furthermore, mortality at 24-month follow up was associated with high NFL levels (p < 0.01). We conclude that analysis of NFL in CSF may become useful in the differential diagnosis of parkinsonian syndromes.

Exposure to extremely low frequency electromagnetic fields and the risk of malignant diseases--an evaluation of epidemiological and experimental findings

Epidemiological and experimental studies concerning extremely low frequency electromagnetic field exposure and malignant diseases published up to 1 July 1994 were evaluated to assess the possible carcinogenicity of electromagnetic fields and the scientific basis for environmental and occupational standard setting. We concluded that there are possible associations between (i) an increased risk of leukaemia in children and the existence of, or distance to, power lines in the vicinity of their residence, (ii) an increased risk of chronic lymphatic leukaemia and occupational exposure to low frequency electromagnetic fields and (iii) an increased risk of breast cancer, malignant melanoma of the skin, nervous system tumours, non-Hodgkin lymphoma, acute lymphatic leukaemia or acute myeloid leukaemia and certain occupations. There is no scientific basis for occupational or environmental standard setting for low frequency electric or magnetic fields.

Magnetic fields and cancer: animal and cellular evidence--an overview

A few animal studies on the possible carcinogenic effect of magnetic fields have been published. They have been designed to reveal a possible tumor promotion obtained by applying continuous or pulsed alternating fields at flux densities varying between 0.5 microT and 30 mT on mice or rats initiated with different initiators. One study with 2 mT applied on DMBA-initiated mice may suggest a copromotive effect together with the promoter TPA. Another study on rats suggests an inhibitory effect by a magnetic field on rat liver foci formation, induced with DENA. Cell studies show that magnetic fields at some frequencies, amplitudes, and wave forms interact with biological systems. Thus effects have been seen, e.g., on enzymes related to growth regulation, on calcium balance in the cell, on gene expression, and on pineal metabolism and its excretion of the oncostatic melatonin. Cellular and physiologic studies thus suggest effects that may be related to cell multiplication and tumor promotion.

The effects of long-term oral administration of ethanol on Sprague-Dawley rats--a condensed report

For a period of 2 years Sprague-Dawley rats received 3% and 1% ethyl alcohol or an equicaloric amount of glucose in a semisynthetic liquid diet. Thereafter the tumour incidence was recorded. For male rats no neoplastic lesions were observed to be related to ethanol exposure. For females, when individual group comparisons were made, an increase in mammary gland tumours was seen for females receiving the low ethanol containing diet. In some tumour frequency comparisons the opposite, namely a decrease in the rate of incidence, was obtained. The overall information seems to indicate the absence of a carcinogenic activity of ethyl alcohol per se after long-term oral administration. Liver and bile duct injury was seen among males. Inflammatory reactions were seen among males in pancreas and for females in the clitoral gland. Hyperplasia was observed in the thyroid gland in both sexes and in the adrenal glands among females. Peripheral nerve degeneration was common in both sexes.

Intermittent 50 Hz magnetic field and skin tumor promotion in SENCAR mice

A number of epidemiological studies have indicated association between exposure to extremely low frequency electromagnetic fields and a variety of cancers, including leukaemia and brain tumours among residentially exposed children and among occupationally exposed adults. In order to test if intermittent magnetic fields (MF) act as a tumour promoter, a long-term skin carcinogenicity study of 50 Hz sinusoidal MF with flux densities of 50 muT and 0.5 mT, continuous as well as with an intermittence of 15 s on/off, was performed. Female SENCAR mice were divided into eight groups of 50 animals in each and treated according to an initiation- promotion scheme. 7,12-dimethylbenz[a] anthracene (DMBA) in acetone was applied to the dorsal skin at a subcarcinogenic dose, as an initiator and exposure to MF was performed for 19-21 h/day during 104 weeks starting 1 week after the initiator treatment. The phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) was used as a positive control for skin tumour promoting activity. Two animals from each group were assigned for skin hyperplasia analysis at 2, 6, 12, 18 and 21 months. The animals were observed daily. The appearance of skin lesions and neoplasms were carefully followed and histopathological diagnosis was made for all neoplasms present at death. The experiment was terminated after 105 weeks. DMBA-treatment alone yielded altogether two skin tumours in two tumour-bearing animals and the animals exposed to acetone alone had one skin tumour. The animals exposed to continuous fields showed no skin tumour. Five animals exposed to 0.5 mT on/off had a total of 13 skin tumours and in the group exposed to 50 microT on/off four animals had a total of four skin tumours. The on/off exposed groups differed significantly from the continuously exposed groups (P = 0.014) but the difference between the on/off exposure groups and the DMBA group was not statistically significant when tumour-bearing animals and cumulated skin tumours were compared. There was a statistically significant dose trend (P = 0.045) with flux density and Tesla-h for intermittent MF exposure for cumulated skin tumours per tumour-bearing animals. The epithelial thickness of DMBA + MF-treated animals was of the same magnitude as for DMBA-treated animals indicating that, in the case of a promoting effect being present, another mechanism than one involving sustained hyperplasia may be involved.

A rat liver foci promotion study with 50-Hz magnetic fields

To investigate the possible tumor-promoting effect of magnetic fields (MF), we have performed two liver foci bioassays in rats which were exposed to MF at four flux density levels (0.5 microT, 5 microT, 0.05 mT, and 0.5 mT). The MF were generated in exposure equipment consisting of copper coils surrounding racks with animal cages and giving homogenous horizontal 50-Hz magnetic fields. Rats previously submitted to partial hepatectomy and diethylnitrosamine treatment were exposed to MF for 12 weeks. Exposed and control rats were kept in separate rooms. As a positive control phenobarbital (PB) was administered for 12 weeks. The number, area, and volume of foci expressing gamma-glutamyl transpeptidase (GGT) and glutathione S-transferase (GST-p) were evaluated. The body weight gains and relative liver weights of MF-exposed rats were not different as compared to control rats. There was a slight increase in GGT-staining foci, but not in GST-p-staining foci, in the groups exposed to flux densities of 0.5 microT and 0.05 mT compared to the control group in the first experiment. The number of both GGT- and GST-p-staining foci in the livers of all MF-exposed groups were, however, within the control range when the results of the two experiments were considered together.

Lymphoma development among mice exposed to X-rays and pulsed magnetic fields

CBA mice were exposed to a total of 5.24 Gy X-rays (260 kV, 11 mA, 0.45 Gy/min), divided into four exposures, and to saw-tooth 15 microT (peak to peak) pulsed vertical 200 kHz magnetic fields for their life-time. In parallel, series with magnetic fields only or non-exposed animals were run. The animals were observed for their life-time. The frequency of lymphomas was 65.7% in the X-ray group and 71.4% in the groups exposed to both X-ray and magnetic field. Of the non-exposed control animals, and of the animals exposed to magnetic fields only 6.4 and 5.7% had lymphomas, respectively. There were no statistically significant differences between the magnetic field series and the corresponding controls for lymphomas. Blood cell counts and haemoglobin data did not show differences between the X-irradiated, and X-ray and magnetic field-exposed groups. Mononuclear cells and total leukocytes were elevated for pulsed magnetic fields-exposed animals compared with the non-exposed controls. This difference was due to two animals with extreme values. In the pulsed magnetic fields treated group there was a statistically significant increase of the carcass weight compared with the non-treated control group.

A study on skin tumour formation in mice with 50 Hz magnetic field exposure

In order to test the possibility that magnetic fields (MF) act as a tumour promoter, a long-term skin carcinogenicity study of 50 Hz sinusoidal MF with flux densities of 50 microT and 0.5 mT was performed in female NMRI mice. 7,12-dimethylbenz[a]anthracene (DMBA) in acetone was applied to the dorsal skin, as an initiator, and exposure to MF was performed for 19 (weekdays) or 21 h/day (weekends and holidays) for 103 weeks starting one week after the initiator treatment. The phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) was used as a positive control for skin tumour promoting activity. MF was also evaluated for complete carcinogenic action in groups of mice that were treated with acetone only. Six animals from each group were taken for skin hyperplasia analysis and were killed after 9, 26 and 52 weeks. The appearance of skin lesions were carefully followed and histopathological diagnosis was made for all neoplasms present at death. The statistical analyses on occurrence of skin tumour bearing animals and cumulated skin tumours, with corrections for survival did not reveal a difference between the controls and the MF exposed groups. The epithelial thickness of DMBA + MF-treated animals was of the same magnitude as for DMBA-treated animals. Leukaemia was a little more frequent among animals exposed to 0.5 mT MF compared to the control animals. However this difference was not statistically significant.

Mortality and cancer incidence among PVC-processing workers in Sweden

The mortality pattern and the cancer incidence were investigated among 717 men who had been employed for at least 3 months during 1964-1974 in three Swedish PVC-processing plants. The mortality was followed 1964-1986 and the cancer incidence 1964-1984. Expected figures were calculated from Swedish national rates. Among Swedish citizens, the observed mortality and cancer incidence was close to the expected in most diagnoses. Among immigrants, mostly from Finland, there was a marked excess of circulatory deaths. This finding was probably due to the higher incidence of coronary mortality in Finland compared to Sweden. In the whole cohort, five cases of malignant melanoma had occurred as compared to 1.5 expected (SMR = 3.4, 95% confidence limit 1.1-7.9). This may be due to chance but merits further investigation since an increased incidence of malignant melanoma has previously been found among Norwegian PVC-manufacturing workers.