The incubation period of kuru

BACKGROUND: Kuru is a transmissible spongiform encephalopathy that was identified in Papua New Guinea in the late 1950s. Several thousand cases of the disease occurred during a period of several decades. Epidemiologic investigations implicated ritual endocannibalistic funeral feasts as the likely route through which the infectious agent was spread. METHODS: We estimated the incubation period distribution of kuru using a back-calculation model and explored the relation among sex, age at infection, and incubation period. Key assumptions in the model were that the number of new kuru infections in a year was proportional to the number of kuru cases dying that year, and that the epidemic arose from a single case of sporadic Creutzfeldt-Jakob Disease occurring around 1900. RESULTS: The mean incubation period of kuru was estimated at between 10.3 and 13.2 years. Point estimates of the 90th percentile ranged from 21.1 to 27.0 years. The incubation period in females was estimated to be shorter than that in males. The shortest incubation periods were estimated in adult women, who may have been exposed to the largest doses of infectious material. CONCLUSIONS: Our findings suggest that the relatively young age of cases of variant Creutzfeldt-Jakob disease probably reflects increased levels of exposure in young people, rather than age-dependency in the incubation period.     

Polymorphism of the codon 129 of the prion protein (PrP) gene and neuropathology of cerebral ageing

We studied whether codon 129 polymorphism of the PrP gene modulates the presence of tau- and Abeta-associated lesions among 188 patients over 70 years of age without evidence of dementia. Val allele carriers, either heterozygotes or homozygotes, were more frequently affected by Abeta-associated lesions than non Val allele carriers, whereas there were no differences for tau-positive neurones. Val allele carriers also had more focal and diffuse Abeta deposits. This association was most significant in the highest Braak's stages for neurofibrillary tangles (>/=III). In this group, cases with at least one Val allele had nearly twice as many Abeta-associated lesions. The most affected areas were the entorhinal cortex, TF-TH and the superior temporal cortex, where odds ratios for focal Abeta deposits ranged from 3.5 to 4.6.     

Bias in association studies resulting from gene-environment interactions and competing risks

The etiology, particularly the genetic basis, of multifactorial late-onset diseases is the subject of many genetic epidemiologic studies. The authors' aim in this paper was to investigate the circumstances under which competing risks can lead to bias in studies of genetic susceptibility to late-onset diseases. The authors used a model built in an epidemiologic framework to show that when a genetic risk factor and an environmental risk factor interact to cause a frequent competing risk of death, the measure of the association between the disease under investigation and the genetic risk factor will be biased if the environmental risk factor is also associated with the latter disease and is omitted from the analysis. This is an example of confounding bias, and it is the consequence of an association between the genetic risk factor and the environmental risk factor that appears over time. Numerical examples show that under certain conditions this bias can be substantial. The authors present several patterns of association in favor of such a bias. Because competing risks of death are likely to be present in older subjects, researchers studying the etiology of late-onset diseases should be aware of the possibility of this bias.     

Approaches to the reversal of malnutrition,inflammation, and atherosclerosis in end-stage renal disease

Uremic malnutrition and chronic inflammation are important comorbid conditions that predict poor clinical outcome in end-stage renal disease (ESRD) patients. These conditions are also closely associated with cardiovascular disease, the major cause of death in ESRD patients. A pathophysiologic link between malnutrition, inflammation, and atherosclerosis has been proposed in this patient population. Indeed, multiple lines of evidence suggest that chronic inflammation can predispose ESRD patients to a catabolic and atherogenic state. Malnutrition can also result from chronic inflammation and can accelerate the progression of cardiovascular disease. Whereas a single common etiology has not been identified in this complex process, nutritional and anti-inflammatory interventions provide potential treatment options to counter the high mortality and morbidity in ESRD patients.     

Proprioception of the ankle: a comparison between female teenaged gymnasts and controls

Proprioceptive mechanisms appear to play a role in stabilizing the joints and may serve as a means for interplay between static stabilizers and dynamic muscular restraints. The purpose of our study was to investigate whether or not gymnastic training has any effect on the balance and on proprioception in an ankle, as seen in gymnasts and in nongymnasts. We evaluated the proprioceptive ability of the ankle using four different tests (a one-leg-standing test, a single-limb-hopping test, an active angle-reproduction test, and a passive angle-reproduction test). Proprioception of the ankle was measured in 40 subjects who were assigned to two experimental groups. Group 1 (n: 20) were healthy control subjects, and group 2 (n: 20) were teenaged female gymnasts. The sense of position of a joint was actively measured using a Cybex NORMTM isokinetic dynamometer and measured passively with a proprioception-testing device. A Mann-Whitney U test was used to compare mean values of the gymnasts to the controls. Results revealed statistically significant differences (p<0.05) between two groups. We found no statistically significant differences between the dominant and nondominant ankle in volunteers or in gymnasts, in all tests. The results of this study suggest that gymnastic training has a positive influence on sense of position of the ankle joint and on balance, in addition to increasing muscle tone.     

A Rare Complication of Adjustable Gastric Banding:Wernicke's Encephalopathy

Background:Wernicke'sencephalopathy is an uncommon complication seen after morbid obesity surgery. Neurological and cardiac symptoms can occur. Early and adequate replacement of thiamin is crucial. Methods: A patient, who was operated by adjustable silicone gastric banding had severe vomiting 1 week after the operation. Physical examination showed no abnormalities except neurological signs consisting of ataxia, disorientation and diplopia. All radiological and biochemical parameters were in the normal range. Result: After replacement of vitamin B₁ (thiamin) intravenously 20 mg twice daily, all the neurological signs regressed day by day. Oral thiamin pills have been continued. Conclusion: Wernicke's encephalopathy which occurs as a result of thiamin deficiency is a rare complication that has serious morbidity with rapidly progressing neurologic symptoms, and must be treated immediately. Surgeons who treat morbidly obese patients must follow the metabolic and nutritional status of the patient.     

Longitudinal study of blood pressure and white matter hyperintensities: the EVA MRI Cohort

OBJECTIVE: To investigate the relationship between baseline hypertension and severity of white matter hyperintensities (WMH) at 4-year follow-up in a sample of subjects aged 59 to 71 years old at entry. METHODS: Subjects were participants in the Epidemiology of Vascular Ageing study, a longitudinal study on vascular aging and cognitive decline. At 4-year follow-up, 845 subjects had a cerebral MRI. MRI examinations were read by a single rater to determine the severity of WMH, ranging from absent to severe. Hypertension at each wave of the study was defined as systolic blood pressure > or =160 mm Hg, diastolic blood pressure > or =95 mm Hg, or use of antihypertensive medication. RESULTS: Hypertension at baseline was significantly associated with an increased risk of having severe WMH at 4-year follow-up. When taking into account both blood pressure levels and antihypertensive drug intake, analysis showed that the risk of having severe WMH was significantly reduced in subjects with normal blood pressure taking antihypertensive medication compared with those with high blood pressure taking antihypertensive agents. Cross-sectional relationships between hypertension and WMH at 4-year follow-up showed that the frequency of severe WMH was significantly higher in people who were hypertensive at both baseline and 4-year follow-up than those who were hypertensive only at 4-year follow-up. CONCLUSIONS: Hypertension is a major risk factor for severe WMH. Subjects taking antihypertensive drugs and who have controlled blood pressure had a reduced risk of severe WMH. Longitudinal studies are needed to investigate whether reduction of the development of WMH, by treatment and prevention of hypertension, might reduce the subsequent risk of cognitive deterioration or stroke.     

Low-Dose Aspirin Does Not Increase Implantation Rates in Patients Undergoing Intracytoplasmic Sperm Injection: A Prospective Randomized Study

Purpose: The aim was to evaluate the effect of aspirin on pregnancy and implantation rates in an unselected group of patients undergoing intracytoplasmic sperm injection (ICSI). Methods: Two hundred and seventy-nine patients were randomized to receive 80 mg of aspirin (n = 139) or no treatment (r = 136) starting from the first day of controlled ovarian hyperstimulation. Results: Duration of stimulation, gonadotropin consumption, peak estradiol, number of oocytes retrieved, fertilization rate, cleavage rate, and number of embryos transferred were similar in the two groups. Implantation and clinical pregnancy rates were 15.6% and 39.6% versus 15.1% and 43.4% in aspirin treated and untreated groups, respectively (P > 0.05). Conclusions: Low-dose aspirin administration does not improve implantation and pregnancy rates in an unselected group of patients undergoing ICSI.     

Colonoscopy and bacteraemia.

A prospective study was performed on 35 patients undergoing colonoscopy. Aerobic and anaerobic blood cultures before, during and after the investigation failed to demonstrate bacteraemia in any instance.