Abstract-To evaluate the clinical application of the second derivative of the fingertip photoplethysmogram waveform, we performed drug administration studies (study 1) and epidemiological studies (study 2). In study 1, ascending aortic pressure was recorded simultaneously with the fingertip photoplethysmogram and its second derivative in 39 patients with a meanϮSD age of 54Ϯ11 years. The augmentation index was defined as the ratio of the height of the late systolic peak to that of the early systolic peak in the pulse. The negative d/a reflects the late systolic pressure augmentation in the ascending aorta and may be useful for noninvasive evaluation of the effects of vasoactive agents. In study 2, the second derivative of the plethysmogram waveform was measured in a total of 600 subjects (50 men and 50 women in each decade from the 3rd to the 8th) in our health assessment center. The b/a ratio increased with age, and c/a, d/a, and e/a ratios decreased with age. Thus, the second derivative aging index was defined as b-c-d-e/a. The second derivative wave aging index (y) increased with age (x) (rϭ0.80, PϽ0.001, yϭ0.023xϪ1.515). The second derivative aging index was higher in 126 subjects with any history of diabetes mellitus, hypertension, hypercholesterolemia, and ischemic heart disease than in age-matched subjects without such a history (Ϫ0. Key Words: photoplethysmography Ⅲ second derivative wave Ⅲ augmentation index Ⅲ vasoactive agents Ⅲ vascular aging Ⅲ angiotensin Ⅲ nitroglycerin N oninvasive pulse wave analysis is useful for evaluation of vascular load and vascular aging. 1 It is usually measured at the palpable artery, including carotid, femoral, and radial arteries.2 These pulse wave tracings provide more precise information concerning blood pressure changes than systolic and diastolic pressures only. 3 The basic idea of the augmentation index was first described by Murgo et al 4 in 1980 in relation to the reflection return point in the ascending aorta. Kelly et al 2 first used the term "augmentation index" in their 1989 study evaluating age-related changes in AIs. They showed age-related increase in AIs at carotid and radial arteries. Ascending aortic pressure can be divided into 2 components at the anacrotic notch, where maximal flow velocity is observed.2 The early systolic component is caused mainly by left ventricular ejection, and the second component is augmented by peripheral reflection wave.5 PTG detects the changes in the amount of light absorbed by hemoglobin, which reflects changes in blood volume. Wiederhelm et al 6 showed pulsatile pressure changes in vessel down to metaarteriole size that corresponded to pulse tracing. PTG has been used to evaluate arterial compliance in relation to changes in the amplitude of wave, 7 but the wave contour itself is not usually used. The SDPTG has been developed to allow more accurate recognition of the inflection points on the original plethysmographic wave, ie, anacrotic or dicrotic notches. In 1972, Ozawa recorded the first and second derivative waves of P...

Meis1 and Hoxa9 expression is upregulated by retroviral integration in murine myeloid leukemias and in human leukemias carrying MLL translocations. Both genes also cooperate to induce leukemia in a mouse leukemia acceleration assay, which can be explained, in part, by their physical interaction with each other as well as the PBX family of homeodomain proteins. Here we show that Meis1-deficient embryos have partially duplicated retinas and smaller lenses than normal. They also fail to produce megakaryocytes, display extensive hemorrhaging, and die by embryonic day 14.5. In addition, Meis1-deficient embryos lack well-formed capillaries, although larger blood vessels are normal. Definitive myeloerythroid lineages are present in the mutant embryos, but the total numbers of colony-forming cells are dramatically reduced. Mutant fetal liver cells also fail to radioprotect lethally irradiated animals and they compete poorly in repopulation assays even though they can repopulate all hematopoietic lineages. These and other studies showing that Meis1 is expressed at high levels in hematopoietic stem cells (HSCs) suggest that Meis1 may also be required for the proliferation/self-renewal of the HSC.

No abstract