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OBJECTIVE: To assess the effect of driver dependent factors on the risk of causing a collision for two wheeled motor vehicles (TWMVs). DESIGN: Case control study. SETTING: Spain, from 1993 to 2002. SUBJECTS: All drivers of TWMVs involved in the 181 551 collisions between two vehicles recorded in the Spanish registry which did not involve pedestrians, and in which at least one of the vehicles was a TWMV and only one driver had committed a driving infraction. The infractor and non-infractor drivers constituted the case and control groups, respectively. MAIN OUTCOME MEASURES: Logistic regression analyses were used to obtain crude and adjusted odds ratio estimates for each of the driver related factors recorded in the registry (age, sex, nationality, psychophysical factors, and speeding infractions, among others). RESULTS: Inappropriate speed was the variable with the greatest influence on the risk of causing a collision, followed by excessive speed and driving under the influence of alcohol. Younger and older drivers, foreign drivers, and driving without a valid license were also associated with a higher risk of causing a collision. In contrast, helmet use, female sex, and longer time in possession of a driving license were associated with a lower risk. CONCLUSIONS: Although the main driver dependent factors related to the risk of causing a collision for a TWMV were similar to those documented for four wheeled vehicles, several differences in the pattern of associations support the need to study moped and motorcycle crashes separately from crashes involving other types of vehicles.

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Depression is a common symptom in Parkinson's disease (PD) and it is present in up to 40% of the patients. The cause of depression in PD is thought to be related to disturbance of monoamine neurotransmission. The endogenous cannabinoid system mediates different brain processes that play a role in the control of behaviour and emotions. Cannabinoid function may be altered in neuropsychiatry diseases, directly or through interactions with monoamine, GABA and glutamate systems. For this reason, we have investigated whether there is a genetic risk factor for depression in PD linked to the polymorphisms of CB1 receptor gene. Depression was more frequent in patients with PD than in controls with osteoarthritis. The presence of depression did not correlate with the stage of the disease but it was more frequent in patients with pure akinetic syndrome than in those with tremoric or mixed type PD. The CB1 receptor gene polymorphism (AAT)n is considered to modify the transcription of the gene and, therefore, it may have functional relevance. We analysed the length of the polymorphic triplet (AAT)n of the gene that encodes CB1 (CNR1) receptor in 89 subjects (48 PD patients and 41 controls). In patients with PD, the presence of two long alleles, with more than 16 repeated AAT trinucleotides in the CNR1 gene, was associated with a reduced prevalence of depression (Fisher's exact test: P=0.003). This association did not reach significant differences in the control group, but the number of control individuals with depression was too small to allow for statistical analysis. Since the alleles with long expansions may have functional impact in cannabinoid neurotransmission, our data suggest that the pharmacological manipulation of cannabinoid neurotransmission could open a new therapeutic approach for the treatment of depression in PD and possibly in other conditions.

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OBJECTIVE: To obtain empirical data that might support or refute the existence of a risk compensation mechanism in connection with voluntary helmet use by Spanish cyclists. DESIGN: A retrospective case series. SETTING: Spain, from 1990 to 1999. SUBJECTS: All 22 814 cyclists involved in traffic crashes with victims, recorded in the Spanish Register of Traffic Crashes with Victims, for whom information regarding helmet use was available. MAIN OUTCOME MEASURES: Crude and adjusted odds ratios for the relation between committing a traffic violation and using a helmet. RESULTS: Fifty four percent of the cyclists committed a traffic violation other than a speeding infraction. Committing a traffic violation was associated with a lower frequency of helmet use (adjusted odds ratio (aOR) 0.63, 95% confidence interval (CI) 0.58 to 0.69). Cycling at excessive or dangerous speed, a violation observed in 4.5% of the sample, was not significantly associated with helmet use either alone (aOR 0.95, 95% CI 0.56 to 1.61) or in combination with any other violation (aOR 0.97, 95% CI 0.79 to 1.20). CONCLUSIONS: The results suggest that the subgroup of cyclists with a higher risk of suffering a traffic crash are also those in which the health consequences of the crash will probably be higher. Although the findings do not support the existence of a strong risk compensation mechanism among helmeted cyclists, this possibility cannot be ruled out.

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BACKGROUND AND PURPOSE: To define the influence of the dose and time on the response to treatment in postoperatively irradiated head and neck cancer patients and to establish a good prediction of failure. METHODS AND MATERIALS: From January 1985 to December 1995, 214 patients with histologically proven head and neck squamous cell carcinomas were irradiated after radical surgery or single tumour resection according to surgical and histopathological findings. The total doses given ranged between 50 and 75 Gy to the primary bed tumour and between 42 and 56 Gy to the neck with fraction sizes of 1.7-2 Gy/day. The median length of the time interval between surgery and radiotherapy, time of irradiation and total treatment time were 81, 59 and 139 days, respectively. The end-point analyzed was the local-regional tumour control rate at the primary tumour bed and neck for 5 years from the beginning of radiotherapy. Univariate and multivariate analyses were used to determine predictors of failure from among the following studied variables: (i), clinical stage (T/N) of the patients; (ii), tumour grade; (iii), neck surgery; (iv), tumour margins; (v), histological tumour nodal extension; (vi), chemotherapy; (vii), normalized total dose; (viii), time interval between surgery and radiotherapy; (ix), time of irradiation; and (x), total treatment time. RESULTS: The actuarial 5-year tumour control rate for the entire group was 72%, and 92% of the patients who achieved local control are currently alive without disease. Tumour control was inversely related to T stage (83% for T2 vs. 57% for T4) and the probability of local control within each stage was dependent on the N status (> or =71% for T3-T4/N0 vs. 31-44% for T3-T4/N1-N3). Histological N status and tumour margins, but not tumour grade, impacted significantly on tumour control. When local control was analyzed as a function of the dose to the primary, a non-significant negative dose-response relationship was found. The total treatment time was a significant prognostic factor, and the time interval between surgery and irradiation proved to be an independent predictor of failure. CONCLUSIONS: Despite the absence of a statistically significant dose-response relationship, the present results suggest that postoperative irradiation treatment given to patients with head and neck squamous cell carcinomas should not be unduly prolonged, in order to minimize the amount of tumour cell proliferation. In these patients, nodal involvement, positive margins of the resected specimens and time interval between surgery and irradiation were the most important prognostic factors.

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OBJECTIVE: To know and compare the beliefs, attitudes and motivations of donors and non-donors in relation with blood donation. MATERIAL AND METHODS: Transversal study by questionnaires administered to 197 blood donors and 303 non-donors. The questionnaires gathered: sociodemographic data, beliefs and attitudes (using a Likert scale), and motivations and demotivations (using upon questions). The responses were analysed using different descriptive analyses and bivariant tests, and factorial analysis and discriminant analysis were performed as multivariant analyses. RESULTS: The donor group had a mean age of 37.8 years, were 58.4 female and 41.6% male, and had made 6.02 donations. The non-donor group had a mean age of 39.8 years and were 53.8% female and 46.2 male. Regarding attitudes and beliefs, the donor group showed more confidence in the good conditions in which donations are performed, had less fears about the possibility that donation can affect health, their attitudes were generally less egotistical, and they had less fears about possible commercialisation of the blood. Both groups believed that blood banks and society itself give inadequate compensation to donors, but this belief was significantly greater among non-donors. Regarding the motivations of donors, the highest proportion were related with a sense of solidarity or duty (26.4%), followed by issues related with information or pressure (23.4%), and the possible personal or family benefits that donation might bring (21.8%). The initial motivations of most donors (75.9%) had not varied with the passage of time, and the factors found to be most demotivating for donation had to do with problems of access and comfort (74.6%). We would highlight that most non-donors denied any worries about blood donation (70.9%) and did not agree that those who need blood should be those who pay for it (92.8%). For non-donors, lack of information (43.6%) and different fears (32.3%) were the principal factors discouraging them from donating. Finally, discriminant analysis selected 11 of the items as providing 75.6% of correct discrimination between the one population and the other. CONCLUSIONS: Donors and non-donors reveal very different beliefs, attitudes and motivations towards blood donation, and the questionnaire employed in this study permits a high degree of discrimination between the two groups. The attitudes of non-donors towards donation are generally less favourable, but allow us to think that a high percentage of these could be changed with the right conditions.

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Synthetic hormone-disrupting chemicals may play a role in the increased frequency of cryptorchidism observed in some studies. We used a spatial ecological design to search for variations in orchidopexy rates in the province of Granada in Spain and to search for relationships between these differences and geographical variations in exposure to pesticides. Orchidopexy rates were estimated for the period from 1980 to 1991 in all municipalities and health care districts served by the University of Granada Hospital. A random sample of males of the same age (1-16 years) admitted for any reason during the same period was used to estimate inpatient control rates. Each municipality was assigned to one of four levels of pesticide use. We used Poisson homogeneity tests to detect significant differences in rates of orchidopexy between districts and between levels of pesticide use. Poisson and logistic regression models were also used to estimate the strength of association between orchidopexy and level of pesticide use. Orchidopexy rates tended to be higher in districts near the Mediterranean coast where intensive farming is widespread. The city of Granada, where the reference hospital is located, also had higher figures both for orchidopexy and inpatient control rates. Regression models showed that the strength of association between orchidopexy and level of pesticide use tended to increase with higher levels of use, with the exception of level 0 (mainly in the city of Granada). Our results are compatible with a hypothetical association between exposure to hormone-disruptive chemicals and the induction of cryptorchidism. Several methodological limitations in the design make it necessary to evaluate the results with caution.

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Diabetic patients commonly have increased urinary excretion of zinc, although blood concentrations may be normal, lowered, or raised. We analyzed zinc levels in plasma and urine after an intravenous overload of zinc sulphate (8 mg) in 22 patients with insulin-dependent diabetes mellitus (IDDM) and 22 healthy individuals. No significant differences were found in basal levels of serum zinc in either group (111 +/- 29 micrograms/dl in IDDM vs 119 +/- 19 micrograms/dl in controls), although urinary excretion of zinc was significantly raised in diabetics (1396 +/- 622 micrograms/24 h) versus controls (611 +/- 235 micrograms/24 h). After zinc overload, both serum and urinary levels of this element varied between the two groups. Serum zinc in IDDM patients initially increased more markedly, and subsequently showed a more significant decline, than in controls. Urinary zinc levels in IDDM patients, in contrast to control values, showed no increase after overload. These alterations in serum and urinary zinc concentrations suggest that our diabetic patients may be zinc-deficient.

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