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In JoVE (1)

Other Publications (11)

Articles by Cynthia Cheng in JoVE

 JoVE Clinical and Translational Medicine

Non-invasive Assessment of Microvascular and Endothelial Function

1Department of Family and Community Medicine, Thomas Jefferson University, 2Department of Pharmacology and Experimental Therapeutics, Biostatistics Division, Thomas Jefferson University, 3Department of Internal Medicine, Thomas Jefferson University


JoVE 50008

Capillaroscopy is a non-invasive, relatively inexpensive methodology for directly visualizing the microcirculation. The forearm blood flow technique provides accepted non-invasive measures of endothelial function.

Other articles by Cynthia Cheng on PubMed

The Reliability of Patient Self-reported Blood Pressures

Self-monitoring of blood pressure actively involves patients in hypertension management. However, the usefulness of self-monitoring of blood pressure may be limited by inaccurate patient reporting. The study objective was to assess reliability of patient blood pressure reporting over 6 months. Forty-nine subjects with Joint National Committee stage 1 or 2 hypertension were enrolled. Unaware that the monitors electronically store readings, the subjects were asked to check and record outpatient blood pressures twice weekly. Stored and written readings were compared. On average, patient-recorded blood pressures were equivalent to stored monitor values 80% or more of the time. Reliability of patient self-reporting was sustained over the 6-month study period. Notably, patients did not selectively report lower blood pressure readings. The overall mean self-reported and stored monitor blood pressures were nearly identical: blood pressure (+/-SD) 134+/-16.8/78+/-11.6 mm Hg and 135+/-19.6/80+/-13.3 mm Hg, respectively. The reliability of self-reporting of blood pressures for many patients supports the potential usefulness of self-monitoring of blood pressure in hypertension management.

Primary Care Physician Beliefs Regarding Usefulness of Self-monitoring of Blood Pressure

Recent studies suggest that the self-monitoring of blood pressure (SMBP) may improve the identification and control of hypertension. Although endorsed by the Joint National Committee VII guidelines, home monitoring is not currently part of the standard care of hypertension.

Practical Therapeutics: an Innovative Residency Drug Education Curriculum

We developed and implemented a drug education curriculum for family medicine residents.

Correlation of Oral Glucose Tolerance Test-derived Estimates of Insulin Sensitivity with Insulin Clamp Measurements in an African-American Cohort

The purpose of this study was to determine which measures obtained from an oral glucose tolerance test (OGTT) are the best estimates of insulin sensitivity measured directly using the euglycemic hyperinsulinemic clamp procedure. Data were examined from a study conducted on 307 young adult African-American men and women. An OGTT with insulin measurements was conducted after a 12-hour overnight fast. The euglycemic hyperinsulinemic clamp was used to measure insulin-stimulated glucose uptake (M) directly. Pearson's correlation analyses were performed to examine the relationship of OGTT-derived parameters with insulin sensitivity measured using the clamp. There were consistent statistically significant correlations between calculated estimates of insulin sensitivity (fasting insulin/fasting glucose, summed insulin/summed glucose, homeostasis model assessment [HOMA], Quantitative Insulin Sensitivity Check Index [QUICKI]) with insulin sensitivity measured by the insulin clamp (P <.001). The calculated estimates that correlated most strongly with clamp measured insulin sensitivity were QUICKI and the logarithm of summed insulin during the OGTT. These data indicate that fasting and OGTT-derived plasma insulin and glucose concentrations can be used to estimate insulin sensitivity in young adult African-Americans when it is not feasible to conduct the insulin clamp procedure. Calculated indices that include log transformation of plasma insulin concentration improve the estimation of insulin sensitivity.

Cholesterol-lowering Effect of the Food for Heart Nutrition Education Program

The objective of this prospective, randomized controlled trial was to assess the effectiveness of the Food For Heart Program patient nutrition tool in hypercholesterolemic outpatients. The setting for this study was an urban academic primary-care practice; 175 hypercholesterolemic adults not taking cholesterol-lowering medications were enrolled as subjects. The study intervention involved four monthly dietary counseling visits, using the Food For Heart Program, conducted by the study research assistant. The main outcome measures were fasting serum lipids (primary); body weight (secondary); and change in Dietary Risk Assessment score (intervention group only), analyzed using Student's t test. Our results showed that total and low-density lipoprotein cholesterol decreased 0.40+/-0.65 mmol/L and 0.32+/-0.58 mmol/L, respectively, in the intervention group (n=91), compared with 0.06+/-0.57 mmol/L and 0.0088+/-0.56 mmol/L in the control group (n=84) ( P <.001). There was no significant change in high-density lipoprotein cholesterol. Intervention subjects lost a small but statistically significant amount of weight, 2.2+/-7.4 pounds ( P <.01), and decreased their Dietary Risk Assessment score 5.9+/-6.5 points ( P <.001). Based on these findings, we concluded that total and low-density lipoprotein cholesterol, weight, and dietary risk for coronary heart disease decreased significantly in hypercholesterolemic patients counseled using the Food For Heart Program.

Validation of the Dietary Risk Assessment Food Frequency Questionnaire Against the Keys Score for Saturated Fat and Cholesterol

The objective of this pilot study was to validate the Dietary Risk Assessment (DRA) food frequency questionnaire against the Keys score obtained from 2 2-day dietary recalls in a sample of subjects.

The Utility of Fasting Glucose for Detection of Prediabetes

Treatment of prediabetes attenuates progression to type 2 diabetes mellitus. The American Diabetes Association (ADA) previously defined prediabetes as either impaired fasting glucose (IFG) = 6.1 to 6.9 mmol/L (110-125 mg/dL) and/or impaired glucose tolerance (IGT) (2-hour postload glucose of 7.8-11.0 mmol/L [140-199 mg/dL]). For practical reasons, fasting plasma glucose (FPG) is commonly used for diabetes screening. Recently, the ADA lowered the fasting glucose threshold value for IFG from 110 to 100 mg/dL. Our objective was to determine the utility of FPG alone for detecting prediabetes in African Americans. Oral glucose tolerance test (OGTT) data from a cohort of 304 young adult African American men and women were examined. We calculated prediabetes prevalence using the previous ADA criteria and examined the effect of lowering the IFG threshold value for IFG to 100 mg/dL. The prediabetes prevalence in this cohort using the previous ADA criteria was 20.4% (n = 62). Of the 62 cases, 8 had IFG, 45 had IGT, and 9 had IFG together with IGT. Fasting plasma glucose testing alone detected 17 (27.4%) prediabetic cases, whereas a complete OGTT detected 54 (87.1%). Lowering the IFG threshold value to FPG = 100 mg/dL identified 13 of the 45 IGT-only cases. However, this lower IFG threshold increased prediabetes prevalence in the overall cohort from 20.4% to 31.9%. In conclusion, in young adult African Americans, an ethnic group at high risk for developing diabetes, FPG testing alone may be inadequate for diagnosing prediabetes. Until alternative strategies are identified, an OGTT is presently the best method for detecting the prediabetic condition in these high-risk patients.

Capillary Rarefaction in Treated and Untreated Hypertensive Subjects

This study aimed to determine if capillary rarefaction is detectable and associated with endothelial dysfunction in persons with mild systolic blood pressure (SBP) elevation. Capillary density and endothelial function were quantified for 150 nondiabetic participants, grouped by blood pressure (BP) as normotensive, untreated high BP, and treated high BP. Structural capillary rarefaction measures were not different between the three groups. Functional capillary rarefaction measures were significantly lower in both high BP groups compared to normotensives, and correlated inversely with endothelial function. The study findings indicate that the hypertensive vascular pathologic process is already underway at modest levels of blood pressure elevation.

Functional Capillary Rarefaction in Mild Blood Pressure Elevation

Capillary rarefaction is described in patients with moderate to severe hypertension. The study objective was to determine if structural and/or functional capillary rarefaction is detectable and associated with endothelial dysfunction in patients with mild blood pressure elevation (HBP: Systolic blood pressure 130 - 160 mm Hg). Capillary density was quantified by direct capillaroscopy in 110 nondiabetic black and non-black subjects. Endothelial function was quantified by plethysmographic measures of flow-mediated vasodilation. Compared to normotensives (NBP: N = 90), functional capillary rarefaction was detected in HBP (N = 20; P<0.001). Functional capillary density measures correlated with endothelial function (P<0.001). Functional, but not structural, capillary rarefaction is detectable and associated with endothelial dysfunction in both black and non-black individuals with mild blood pressure elevation.

Association of Capillary Density and Function Measures with Blood Pressure, Fasting Plasma Glucose, and Insulin Sensitivity

The pathophysiology underlying the association between hypertension and insulin resistance remains unclear. The study purpose was to determine whether reduced capillary density and/or function underlie, and may therefore explain, this association. The study was conducted on 115 black and non-black participants aged 18 to 55 years: 91 with normal blood pressure (systolic blood pressure [SBP] <130 mm Hg) and 24 with mild blood pressure elevation (SBP 130-159 mm Hg). Capillary density and function were quantified using direct capillaroscopy measures. Insulin sensitivity (IS) was estimated using the Quantitative Insulin Sensitivity Check Index (QUICKI). Endothelial function (EF) was measured using strain-gauge plethysmography. Data were analyzed by linear regression adjusted for age, sex, race, and body mass index (BMI). After adjustment for BMI, capillary density and function measures were significant predictors of SBP ( P<.01), fasting plasma glucose (P=.012, P=.03, and P=.004, respectively), and EF (P=.033, P=.001, and P=.009, respectively). However, none of the capillary measures were significant predictors of fasting insulin or IS. These capillaroscopy data demonstrated an association with SBP but not insulin resistance, suggesting that capillary measures are unlikely to explain the association between hypertension and insulin resistance, at least with modest degrees of blood pressure elevation.

Alterations in Capillary Morphology Are Found in Mild Blood Pressure Elevation

Remodeling of small resistance arteries is an early sign of target organ damage in hypertension. Peripheral capillary morphology abnormalities in hypertension are not well studied. The study objective was to determine whether altered capillary morphology is associated with SBP, DBP, or both in individuals without and with mild blood pressure elevation (SBP = 130-160 mmHg). Another objective was to determine whether capillary morphology is associated with minimum forearm vascular resistance, a measure of altered resistance artery structure.

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