Americans' Awareness, Knowledge, and Behaviors Regarding Fats: 2006-2007

In recent years, epidemiologic and clinical studies, public and regulatory policy activity, and media coverage have focused on issues related to trans fats. To help increase awareness and understanding of trans fats and other fats, the American Heart Association (AHA) launched the “Face the Fats” national consumer education campaign in April 2007. The AHA commissioned a quantitative tracking survey between 2006 and 2007 to measure changes in consumer awareness, knowledge, and behaviors related fats and oils and their perceived impact on heart disease. The survey was conducted by Cogent Research. Data were collected during March 2006 and May 2007. At both time points, the survey included a representative sample of the American population age 18 to 65 years (n=1,000). The sampling plan for the survey was designed based on the 2000 and 2003 US Census. The margin of error was ±3.10 percentage points. Awareness of trans fats increased during the 1-year study period. In 2007, 92% of respondents were aware of trans fats, an increase from 84% in 2006 (P<0.05). The 2007 level was similar to the awareness of saturated fats (93%). Perceptions that certain fats and oils heighten the risk of heart disease increased for trans fats (73% in 2007 vs 63% in 2006; P<0.05), saturated fats (77% in 2007 vs 73% in 2006; P<0.05), and partially hydrogenated oils (56% in 2007 vs 49% in 2006; P<0.05). Knowledge about food sources of different fats remained low. On an unaided basis, 21% could name three food sources of trans fats in 2007, up from 17% in 2006 (P<0.05). Knowledge of food sources of saturated fat remained unchanged at 30% in 2007. Significantly more respondents in 2007 reported behavioral changes related to trans fat information, such as buying food products because they show “zero trans fat” on labels or packages (37% in 2007 vs. 32% in 2006; P<0.05). Between 2006 and 2007, consumer awareness about trans fats increased and attained awareness levels similar to saturated fats. The increased awareness is associated with improved self-reported behaviors in grocery shopping. Nonetheless, overall knowledge, especially regarding food sources of saturated and trans fats, remains relatively low, underscoring the need for heightened consumer education activities. The positive change in consumer awareness about trans fats is likely attributable to the wide range of messages available to them, including the AHA “Face the Fats” national consumer education campaign.     

Microcirculatory changes in livers of mice infected with murine hepatitis virus. Evidence from microcorrosion casts and measurements of red cell velocity

Hepatitis has been considered, classically, as a diffuse hepatocellular necrosis, and little attention has been paid to the relationship of lesions to the microvasculature. In livers of mice (Balbc/J) infected with murine hepatitis virus (MHV-3), microcorrosion casts showed spherical cavities where casting compound was unable to fill sinusoids. At 48 hr postinfection such "lesions" had a mean diameter of 83 micron +/- 26 (SD) and their number/mm2 (at the surface of casts) was 0.95 +/- 1.3. Blind-ended sinusoids formed a distinct boundary between perfused and nonperfused areas, and concave impressions at their ends indicated cells blocking the lumen. In vivo microscopy of transilluminated livers in infected mice showed localized rounded areas without flow, corresponding to lesions seen in casts. RBC velocity measurements in sinusoids adjacent to lesions demonstrated that velocities fall from normal values to zero over a narrow border zone. Beginning with the most proximal sinusoid with visible flow and moving outward from the lesion to the second and third sinusoids, mean RBC velocities (micron/sec, +/- SD) were 17.4 +/- 6.7, 33.9 +/- 8.7, 66.6 +/- 27.3, respectively; this last value was not significantly different from velocities in normal liver (69.2 +/- 30.6). Transmission electron microscopy of livers of infected mice confirmed the presence of sinusoidal lumens blocked by protruding lining cells, RBCs, platelets, swollen hepatocytes, and cellular debris. This study demonstrates that the lesions are focal in origin, microvascular blockage leading to gradually increasing necrosis in all directions.     

Spontaneous cyclic contractions of the capillary wall in vivo, impeding red cell flow: a quantitative analysis. Evidence for endothelial contractility

We have videorecorded spontaneous cyclic contractions of capillary walls which often stopped the flow of blood cells, in spleens of rat and mouse. An inverted microscope and oblique lighting were key elements in obtaining images in which the boundaries of cells composing vessel walls were clearly distinguishable. Using slow motion replay, we measured the widths of endothelial cells (C), pericytes (P, when present) and capillary lumens (L; at the site of constriction; U; 15-20 micron upstream), throughout 11-12 min sequences containing many contraction/relaxation cycles. In roughly 50% of contractions L decreased to 0-1 micron, such luminal "closures" occurring within 2-12 sec and lasting for less than 1 sec to greater than 1 min. Intervals between contractions ranged from 12 sec to 3 min (average 1 min). Documentation of one such cycle by sequential photographs from the video monitor is presented, showing dramatic bulging of an endothelial cell into the lumen. Comparison of records of L and C versus time showed that almost invariably when L decreased C increased, and vice versa; highly significant correlations existed between C and L in every case (P less than 0.0005). Multiple linear regression analysis showed that changes in C were responsible for 18-77% of the total variance in L, whereas P contributed only 0-4%; changes in U, covariance between C, P, and U, and unexplained variance were responsible for 0-20, 11-30, and 11-53%, respectively, of the total variance in L. We conclude that these spontaneous capillary contractions were primarily due to endothelial contractility.