Brain tissue water comes in two pools: evidence from diffusion and R2' measurements with USPIOs in non human primates.

Diffusion-weighted MRI of non-human primates revealed that USPIO Bulk Magnetic Susceptibility (BMS) T2' effects of Ultrasmall Superparamagnetic Particles with Iron Oxide (USPIO) in the brain cannot be explained by a single compartment model, as diffusion and T2' effects appear coupled: Apparent Diffusion Coefficient (ADC) values depend on USPIO concentration and relaxivity effects of USPIO decrease with the b value. On the other hand, USPIO and diffusion effects could be well uncoupled using a model consisting in a fast and a slow diffusion pool with different relaxivities. Diffusion-weighting acts as a filter which emphasizes the contribution of the slow pool when increasing b values (apparent decrease in ADC and R2'). Those results have implications for human studies using BMS contrast agents, as well as BOLD and diffusion fMRI.

Dark tobacco and lung cancer in Cuba.

PIP: A retrospective case control study of lung cancer was conducted in Havana, Cuba to investigate whether Cuban high lung cancer mortality rates could be explained by cigarette and cigar consumption habits, including the smoking of dark tobacco cigarettes. The cases were drawn from patients admitted from 1978 to 1980 to the city's 12 main general hospitals with a tentative diagnosis of lung cancer. Only patients whose final diagnosis was confirmed by cytology and/ or histology according to the World Health Organization's Classification of Lung Cancer were included. A hospital control selected from patients with a current admission for a nonsmoking-related disease was matched to each case by sex, age, hospital of admission, and admission date. Data on 826 confirmed lung cancer cases (219 females and 607 males), 979 hospital controls, and 539 neighborhood controls were analyzed with procedures for matched and unmatched studies. Lung cancer patients ranged in age from 23 to 89 years; approximately 1/2 were females and 2/3 of the males were 60 years or older at diagnosis. Education level was similar in all groups. 167 of the 219 female cases (76.3%) and 595 of the 607 male cases (98%) ever smoked regularly, compared with 31% and 80.3%, respectively, of female and male controls. The corresponding proportions for female hospital and neighborhood controls were 30.5 and 31.8%, whereas for males they were 80.5% and 80.1%. The overall relative risk (RR) of lung cancer in cigarette smokers was 7.3 for females and 14.1 for males. Most smokers consumed the local dark tobacco ciagrettes exclusively. There were increased risks of lung cancer in both sexes associated with smoking both tobaccos, but the excess was greater for dark tobacco. The differences were reduced after adjustment for amount smoked. With either dark or light tobacco, the longer the duration of smoking or the greater the total number of cigarettes consumed, the higher the risk, all trends being highly significant. Cigarette smoking was associated with all 4 histologic types of lung cancer. A separate analysis was done on the 216 male cases and 389 controls who smoked either cigars only or cigars plus cigarettes. The risk of lung cancer in both groups was greater than those in nonsmokers. Based on attributable risk, it is estimated that a maximum of 66% of female and 91% of male lung cancer cases in Cuba are due to smoking.^ieng

Dark tobacco and lung cancer in Cuba.

A retrospective epidemiologic study of 826 cytologically and/or histologically confirmed lung cancer cases (219 females and 607 males), 979 hospital controls, and 539 neighborhood controls was undertaken in Havana, Cuba, to investigate whether the high lung cancer mortality rates in this country could be explained by the cigarette and cigar consumption habits, including the smoking of dark-tobacco cigarettes. Relative risk(s)(RR) of lung cancer among cigarette smokers were 7.3 in women and 14.1 in men and increased consistently with various measures of exposure to smoke. The findings suggested that duration of smoking, daily number of cigarettes consumed, and inhalation practices have independent effects. Most Cubans smoked dark tobacco. RR were higher for dark-tobacco users than for light-tobacco users (RR = 8.6 vs. 4.6 for women and 14.3 vs. 11.3 for men), but the differences were reduced after adjustment for amount smoked. Cigarette smoking was associated with all histologic types of lung cancer, although the risk for adenocarcinoma was lower than that for the other types. Men who smoked exclusively cigars had a fourfold risk of lung cancer. Mixed smokers (i.e., cigar and cigarette smoker) had a greater RR than cigarette-only smokers (15.0 vs. 14.1), which was perhaps related to the unusually deep and frequent inhalation of cigar smoke. The data support the hypothesis that smoking patterns account for the higher lung cancer mortality in Cuba than in other Latin American countries.