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A national survey of health risk perception among 1,503 Canadians was conducted in 2004. The current survey follows-up a previous national survey conducted in 1992 and documents changes in risk perception since that time and investigates new risk issues not previously examined. This article presents a description of the ratings of perceived risk of thirty specific hazards to the Canadian population, sources of information about health issues and risk, and confidence in these information sources. Of the specific hazards considered, behavioral risks such as cigarette smoking, obesity, and unprotected sex were seen to present the greatest risk to the health of Canadians. Hazards related to the social environment (e.g., homelessness, street crime, unemployment) were seen as posing moderately high health risks. Medical devices or therapies (e.g., prescription drugs, vaccines, laser eye surgery) tended to rank the lowest in terms of health risk. Women, older respondents, and those with less education reported risks as being higher than men, younger respondents, and those with more education respectively. Large geographical differences in risk perception were also observed. Participants described receiving "a lot" of information from the news media, medical doctors, and the Internet but reported the greatest amount of confidence in medical doctors, university scientists/scientific journals, and health brochures/pamphlets.

A series of five experiments was carried out in which fear of context caused by exposure to shocks was manipulated by signaling the shocks with a discrete stimulus, signaling the days during which shocks occurred with a session-long stimulus, or switching the context between exposure and the subsequent test. All these manipulations influenced fear of the context in the manner predicted by the Rescorla-Wagner associative model. Following this, all the rats were given conditioning trials with shock and a different discrete stimulus. All preexposure treatments produced consistent and reliable interference with conditioning with the exception of signaling the shocks with a discrete stimulus, which greatly reduced interference. These results are interpreted as being consistent both with a cognitive explanation of the US exposure effect, which claims that animals learn that shocks are unpredictable during conditioning and this knowledge retards future conditioning when they are predictable, and with an adaptation explanation, which claims that unpredictable shocks produce chronic fear and this fear through either a change in adaptation level or through emotional exhaustion renders the shocks less reinforcing during the conditioning test.

HLA DR4 antigens have been considered as a risk factor in periodontal disease. The aim of this "case control" study was to verify and to provide fuller clarification of such data. "Cases" or patients had to be aged between 20 and 48 years. They presented at least 5 sites spread over several teeth with an attachment loss equal or greater than 6 mm, and 10 sites spread over several teeth with periodontal pockets equal to or greater than 5 mm. Verification with a WHO probe showed an individual CPITN score of 4. Moreover, subjects whose average CPITN score for the 6 sextants was less than 3 were excluded from the study. Among these "severe periodontitis" patients, a subgroup was distinguished composed of subjects aged 20-35 years who presented, in accordance with the cases by Katz and co-workers, 5 or more teeth showing pocket depths of 6 mm or more. The dental chartings of these subjects showed an attachment loss of more than 3 mm on certain teeth over an inter-exam period of 1-3 years. They all displayed obvious loss of bony support in the affected sites. This constituted the "rapidly progressive periodontitis" subgroup. The "controls" were all over 20 years of age, and it was clinically verified that they were free of periodontal disease. There were 48 "cases" and 55 "controls". HLA typing of patients and controls was performed using "sequence oligoprobe hybridization after polymerase chain reaction" in accordance with the 11th International Workshop. This method allowed the detection of DR4 alleles as well as DR4 subtypes. The ethno-geographic origin of the subjects, considered as a confounding variable, was neutralized by stratified analysis. Subtypes 0401, 0404, 0405 and 0408 tended to be more frequent (p=0.08) in the cases (Severe Periodontitis). Focusing on analysis of "rapidly progressive periodontitis" in subjects aged 20-35 years, a very significant Mantel-Haenszel chi2 was obtained (p=0.0058) which led to a Mantel-Haenszel standardized odds ratio (OR) equal to 17. The 95% confidence interval was 1.03<0.R.<180.10. In conclusion, this supports previous reports and gives further clarification: in particular subtypes 0401, 0404, 0405 and 0408 can be considered as a risk factor for "rapidly progressive periodontitis". It should be noted that these determinants have been implicated in rheumatoid arthritis.

Background: Scoliosis is the most common type of spinal deformity. In North American children, adolescent idiopathic scoliosis (AIS) makes up about 90% of all cases of scoliosis. While its prevalence is about 2% to 3% in children aged between 10 to 16 years, girls are more at risk than boys for severe progression with a ratio of 3.6 to 1. The aim of the present study was to test the hypothesis that idiopathic scoliosis interferes with the mechanisms responsible for sensoryreweighting during balance control.

In conclusion, HLA-DRB1*0101, DRB1*0102, and DRB1*1001, which share a common DRB1 sequence, appeared to be overrepresented in Jk(a)-immunized patients.

Summary K immunisation is observed in some polytransfused patients and pregnant women but does not occur in all cases of K incompatibility. This study analysed the role of genetic background in this selective response to K antigen by investigating HLA‐DRB1 alleles associated with K immunisation in a southern European population. HLA‐DRB1 genotyping was performed by polymerase chain reaction sequence‐specific oligonucleotide/sequence‐specific primer procedures in 54 K immunised patients and 200 healthy controls. The frequency of HLA‐DRB1*11 was significantly higher in K immunised patients than healthy controls: 31 of 54 (57%) vs. 56 of 200 (28%) (Pc < 0·001). In the remaining K immunised HLA‐DRB1*11‐negative patients, the frequency of HLA‐DRB1*13 was increased: 14 of 23 (61%) vs. 49 of 144 in healthy controls (34%) (P < 0·02). The combined frequency of the two HLA‐DRB1 alleles (HLA‐DRB1*11 and HLA‐DRB1*13) was 83% in K immunised patients when compared with 52% in healthy controls (Pc < 0·001). K and k differ by a single amino acid T193 (M). The DRB1*11 and DRB1*13 alleles share a HLA‐DRB1 gene sequence containing S in position 13, D in 70 and A in 74, and coding for the P4 pocket within the HLA‐DR binding groove. This feature of the HLA‐DRB1 gene could be involved in the K peptide presentation through a polymorphism ligand specific for the T193 (M) of K. In conclusion, this study demonstrated a high frequency of HLA‐DRB1*11 or HLA‐DRB1*13 alleles in K immunised patients, which could be due to specific K peptide presentation by HLA‐DR molecules.

Balance control is influenced by the availability and integrity of sensory inputs as well as the ability of the balance control mechanisms to tailor the corrective action to the gravitational torque. In this study, to challenge balance control, visual and ankle proprioceptive information were perturbed (eyes closed and/or tendon vibration). We masked sensory inputs in order: (1) to test the hypothesis that adolescent idiopathic scoliosis (AIS), compared to healthy adolescent, relies more on ankle proprioception and/or visual inputs to regulate balance and (2) to determine whether it is the variation or the amplitude of the balance control commands of AIS that leads to greater body sway oscillations during sensory deprivation. By manipulating the availability of the sensory inputs and measuring the outcomes, center of pressure (CP) range and velocity variability, we could objectively determine the cost of visual and/or ankle proprioception deprivation on balance control. The CP range was larger and the root mean square (RMS) of the CP velocity was more variable for AIS than for control participants when ankle proprioception was perturbed. This was observed regardless of whether vision was available or not. The analysis of the sway density curves revealed that the amplitude rather than the variation of the balance control commands was related to a larger CP range and greater RMS CP velocity for AIS. The present results suggest that AIS, compared to control participants, relies much more on ankle proprioception to control the amplitude of the balance control commands.