Ryuichi Takano

Circulating endothelial progenitor cells are reduced in hemodialysis patients

SUMMARY Objective: The risk of cardiovascular disease in hemodialysis patients is far greater than in the general population. Endothelial progenitor cells (EPCs) circulating in the peripheral blood contribute to neovascularization in the ischemic tissue. EPCs are considered to be included in CD34 positive (CD34+) or AC133 positive (AC133+) mononuclear cells (MNCs). This studys aim was to determine the number and functional activity of EPCs in hemodialysis patients and age-matched control subjects. Methods: The numbers of CD34+ MNCs and AC133+ MNCs in the peripheral blood were quantified by flow cytometry. The peripheral blood EPCs were also examined by an in vitro culture assay. The levels of serum vascular endothelial growth factor (VEGF) were measured by sandwich enzyme immunoassay. Results: The numbers of CD34+ MNCs and AC133+ MNCs were significantly reduced by 56% and 49%, respectively, in hemodialysis patients (n = 50) compared with control subjects (n = 36). The number of EPCs determined by the culture assay was also significantly reduced by 41% in hemodialysis patients compared with control i subjects. Multivariate analysis revealed that none of the atherosclerotic risk factors were independent predictors of reduced CD34+ MNC counts. The serum VEGF levels in hemodialysis patients were not different from those in control subjects and did not correlate with CD34+ MNC counts. Conclusion: Circulating EPCs are significantly reduced in hemodialysis patients, which might be related to impaired neovascularization and cardiovascular disease in these patients.

Texture analysis with a new method in which the region of interest is segmented into multiple layers for radiofrequency amplitude histogram analysis of fibrous rat livers.

PurposeThe aim of this study was to estimate the severity of fibrosis without a biopsy.MethodsThe signal-to-noise ratio (SNR), skewness, and kurtosis were measured using a 10-MHz transducer with the texture analysis in conjunction with an alternative method for evaluating fibrous rat livers. This method segments the region of interest (ROI) into multiple layers (sub-ROIs). In each sub-ROI of a homogeneous medium, the histogram of enveloped amplitude of radiofrequency (RF) backscattered echoes resembles a Rayleigh distribution. In theory, SNR, skewness, and kurtosis for Rayleigh statistics are constant and independent of the mean scattering intensity, which is enhanced by such undesirable effects as tissue attenuation, beam diffraction, and incident waveforms. Thus, these values, which are averages of the corresponding sub-ROI values, constitute an unbiased estimator. All fibrous liver specimens were induced using the dimethylnitrosamine method. Fiber content was estimated quantitatively as the fibrosis index by computer processing of pathological images obtained by light microscopy.ResultsThe SNR, skewness and kurtosis, expressed as averages of corresponding values from each sub-ROI, correlated closely with the fibrosis index.ConclusionThese results make it possible to predict the severity of liver fibrosis from data obtained without resorting to biopsy. The data, obtained from our earlier study on rats, may be used to evaluate human hepatitis quantitatively by measuring these three values. The method may make it possible to estimate the degree of severity of chronic liver disease noninvasively.

Measurement of renal blood flow in human subjects using the ultrasound velocity profiling technique.

PurposeTo (1) assess the accuracy of the ultrasound velocity profiling (USVP) technique of renal blood flow (RBF) measurement in normal subjects and (2) compare renal blood flow measurements obtained using USVP and renal clearance rate in patients with renal diseases.MethodsFirst, we calculated unilateral renal blood flow (unil-RBF) using USVP and the clearance rate of para-aminohippuric acid (CPAH) simultaneously in six healthy male subjects. We then compared unil-RBFUSVP and unil-RBFPAH in nine patients with chronic glomerulonephritis (CGN).ResultsIn the first study, the limits of agreement in a Bland-Altman plot ranged from −325.3 to 32.0 ml/min per 1.48 m2. The mean bias was −146.7 ml/min per 1.48 m2. Subdivision for values of unil-RBFUSVP by flow showed small discrepancies in values above 280 ml/min per 1.48 m2: mean bias, −98.2 ml/min per 1.48 m2; limits of agreement, −223.3 to 26.8 ml/min per 1.48 m2. The three patients in the second study had immunoglobulin A (IgA) nephropathy, in whom unil-RBFPAH was estimated as being markedly lower than unil-RBFUSVP, contrary to the primary result.ConclusionDespite its consistent negative bias, USVP may be a reliable method of quantifying renal blood flow noninvasively when measured values exceed 280 ml/min per 1.48 m2. We assumed that the p-aminohippurate extraction rate (EPAH) was profoundly impaired in the three patients with IgA nephropathy.