1,994 research outputs found

    The heart in orthostatic hypotension

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    The green chemistry and Filipino approach to high school experiments in Saint Paul College Pasig

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    This paper is a call for teachers to initiate measures in improving the quality of high school chemistry education in the Philippines and that is by going back to practical laboratory work. The experiment presented in this paper is a proof to the possibility of tailor-made experiments that integrate principles of green chemistry. Integrating green chemistry concepts in the design of high school chemistry experiments makes students aware of the responsibility that goes with the use and production of chemicals. Moreover, the experiment was designed to consciously integrate aspects of Filipino culture, values, and traditions. Such enculturation of chemistry by giving it a Filipino flavor aims to make the students own the science and not view it as something that is highly foreign. When students can relate to the chemical concepts illuminated in their culture they become more appreciative and receptive of the science giving them meaningful and lasting learning

    CGH Figure Testing of Aspherical Mirrors in Cold Vacuums

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    An established method of room-temperature interferometric null testing of mirrors having simple shapes (e.g., flat, spherical, or spheroidal) has been augmented to enable measurement of errors in the surface figures of off-axis, non-axisymmetric, aspherical mirrors when the mirrors are located inside cryogenic vacuum chambers. The established method involves the use of a computer-generated hologram (CGH), functionally equivalent to a traditional null lens, to modify the laser beam of an imaging interferometer to obtain a reference wavefront that matches the ideal surface figure of a mirror under test. The CGH is inserted at the appropriate position and orientation in the optical path of the imaging interferometer, which, in turn, is appropriately positioned and oriented with respect to the mirror under test. Deviations of the surface figure of the mirror from the ideal surface figure manifest themselves as interference fringes. Interferograms are recorded and analyzed to deduce figure errors

    The metabolic cost of lowering blood pressure with hydrochlorothiazide

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    Abstract Background The landmark Antihypertensive and Lipid-Lowering treatment to prevent Heart Attack Trial (ALLHAT) placed a new spotlight on thiazide diuretics as the first-line therapy for hypertension. This is concerning as thiazide-diuretics may contribute to comorbidities associated with the current epidemic of obesity. Previous randomized clinical trials have linked thiazide diuretic treatment to insulin resistance, metabolic syndrome, and increased incidence of type 2 diabetes. Methods This proof of concept, longitudinal, randomized, double–blind study evaluated the effects of the angiotensin II receptor blocker Valsartan and the specific thiazide diuretic Hydrochlorothiazide (HCTZ) on hepatic triglyceride level (primary outcome), as well as triglyceride levels within other organs including the heart, skeletal muscle, and pancreas. Additionally, we evaluated whether myocardial function, insulin sensitivity, and insulin secretion were affected by these treatments. Results Hepatic TG levels increased by 57% post HCTZ treatment: ∆hTG HCTZ = 4.12% and remained unchanged post Valsartan treatment: ∆hTG V = 0.06%. The elevation of hepatic TG levels after HCTZ treatment was additionally accompanied by a reduction in insulin sensitivity: ∆SI HCTZ = -1.14. Treatment with Valsartan resulted in improved insulin sensitivity: ∆SI V = 1.24. Treatment-induced changes in hepatic TG levels and insulin sensitivity were statistically significant between groups (phTG = 0.0098 and pSI = 0.0345 respectively). Disposition index, DI, remained unchanged after HCTZ treatment: ∆DI HCTZ = -141 but it was increased by a factor of 2 after treatment with Valsartan: ∆DI V =1018). However, the change between groups was not statistically significant. Both therapies did not modify abdominal visceral and subcutaneous fat mass as well as myocardial structure and function. Additionally, myocardial, pancreatic, and skeletal muscle triglyceride deposits remained unchanged in both therapeutic arms. Conclusions Our findings are two-fold and relate to hepatic steatosis and insulin sensitivity. HCTZ treatment worsened hepatic steatosis measured as hepatic triglyceride content and reduced insulin sensitivity. Valsartan treatment did not affect hepatic triglyceride levels and improved insulin sensitivity. The results of this study reinforce the message that in patients at risk for type 2 diabetes it is particularly important to choose an antihypertensive regimen that lowers blood pressure without exacerbating patient’s metabolic profile

    Left ventricular hypertrophy is more prevalent in blacks than whites in the general population: The Dallas heart study

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    Although recent studies have suggested that blacks compared with whites have an increased prevalence of left ventricular hypertrophy, it remains uncertain whether this is true despite adjustment for body composition (fat mass and fat-free mass) and when assessed by cardiac MRI in the general population. The Dallas Heart Study is a population-based study of Dallas County in which 1335 black and 858 white participants 30 to 67 years of age underwent detailed assessment including dual-energy x-ray absorptiometry scan to measure body composition and cardiac MRI. Left ventricular hypertrophy, whether defined by indexation to body surface area (P\u3c0.001), fat-free mass (P=0.002), or height2.7 (P\u3c0.001) was 2- to 3-fold more common in black versus white women. Similar results were seen when comparing black and white men (P\u3c0.001 when left ventricular hypertrophy was indexed to body surface area or height2.7 and P=0.05 when indexed to fat-free mass). Ethnic disparities in left ventricular mass persisted in multivariable models despite adjustment for fat mass, fat-free mass, systolic blood pressure, age, gender, and measures of socioeconomic status. We conclude that blacks compared with whites have increased left ventricular mass and a 2-to 3-fold higher prevalence of left ventricular hypertrophy in the general population, as assessed by cardiac MRI. The ethnic differences in left ventricular mass are independent of differences in body composition. © 2005 American Heart Association, Inc

    Elevated glutamatergic compounds in pregenual anterior cingulate in pediatric autism spectrum disorder demonstrated by 1H MRS and 1H MRSI.

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    Recent research in autism spectrum disorder (ASD) has aroused interest in anterior cingulate cortex and in the neurometabolite glutamate. We report two studies of pregenual anterior cingulate cortex (pACC) in pediatric ASD. First, we acquired in vivo single-voxel proton magnetic resonance spectroscopy ((1)H MRS) in 8 children with ASD and 10 typically developing controls who were well matched for age, but with fewer males and higher IQ. In the ASD group in midline pACC, we found mean 17.7% elevation of glutamate + glutamine (Glx) (p<0.05) and 21.2% (p<0.001) decrement in creatine + phosphocreatine (Cr). We then performed a larger (26 subjects with ASD, 16 controls) follow-up study in samples now matched for age, gender, and IQ using proton magnetic resonance spectroscopic imaging ((1)H MRSI). Higher spatial resolution enabled bilateral pACC acquisition. Significant effects were restricted to right pACC where Glx (9.5%, p<0.05), Cr (6.7%, p<0.05), and N-acetyl-aspartate + N-acetyl-aspartyl-glutamate (10.2%, p<0.01) in the ASD sample were elevated above control. These two independent studies suggest hyperglutamatergia and other neurometabolic abnormalities in pACC in ASD, with possible right-lateralization. The hyperglutamatergic state may reflect an imbalance of excitation over inhibition in the brain as proposed in recent neurodevelopmental models of ASD
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