Biomedical subjects

L Yao

Publications and source records attributed to L Yao.

At least 37 records · Page 2Linked to original sources

PubMed2001

Improvement of left ventricular diastolic dynamics in prediabetic stage of a type II diabetic rat model after troglitazone treatment.

Troglitazone, an oral antidiabetic agent, has hypoglycemic effects in insulin-resistant animal models and humans. This study was conducted to evaluate its effect on left ventricular diastolic dynamics of a spontaneous diabetic (DM) rat model. Twenty DM rats and 20 age-matched nonDM rats were used, and 10 of each group were treated with troglitazone as a 0.2% food admixture for 10 weeks. At 5 and 15 weeks of age, Doppler echocardiography and M-mode echocardiography were performed. Troglitazone treatment significantly improved the left ventricular diastolic dynamics of DM rats: deceleration time (msec) of early diastolic inflow decreased significantly (treated 52 +/- 3 vs untreated 64 +/- 5, p = 0.0002), and peak velocity of early transmitral inflow (cm/sec) increased significantly (treated 96 +/- 7 vs untreated 86 +/- 8, p = 0.0216). The data suggest that troglitazone improves left ventricular diastolic dynamics of a DM rat model at prediabetic stage.

Animals↗

PubMed2001

Acute effect of human cardiotrophin-1 on hemodynamic parameters in spontaneously hypertensive rats and Wistar Kyoto rats.

There is considerable evidence to indicate that humoral factors play an important role in the development of left ventricular hypertrophy. Cardiotrophin-1 (CT-1) is a cytokine that has been shown to induce cardiac hypertrophy in a dose-dependent manner. The aim of the present study was to investigate the acute effect of CT-1 on hemodynamic parameters in spontaneously hypertensive rats (SHR) and Wistar Kyoto rats (WKY) and to study the relationship between the plasma concentration of CT-1 and its hemodynamic effect. Ten-week-old SHR and age-matched WKY were used. Blood pressure (BP), heart rate (HR) and plasma concentration of CT-1 were measured both before and for 60 min after intravenous bolus injection of human CT-1 (10 microg/kg). CT-1 injection significantly decreased BP and significantly increased HR in SHR and WKY. There were significant differences in BP and HR between the two groups at all time points after injection. The lowest BP, highest HR and maximal plasma concentrations of CT-1 were observed in both groups within 10 min after injection. However, after converting the values into the percentage change from their respective baselines, there were no significant differences between the two groups in BP or HR at any time point. There was also no significant difference between the two groups at any time point in the plasma concentration of CT-1. This study indicates that CT-1 decreases BP and increases HR in both SHR and WKY. The most obvious change occurred within 10 min after injection. However, there was no significant difference in the hypotensive effect of CT-1 on 10-week-old SHR and WKY.

Animals↗

PubMed2001

Influence of BOL on hyaluronic acid, laminin and hyperplasia in hepatofibrotic rats.

AIM: To study the anti-hepatofibrosis mechanism of Bie Jia Jian oral liquid (BOL). METHODS: The model was induced by subcutaneous injection of CCl(4). BOL was administered and the change of serum hyaluronic acid (HA) and laminin (LN) was observed and the degeneration of liver cells and the degree of fibre hyperplasia analyzed. Changes of ultra micro-structure in liver cells were observed in some samples. RESULTS: HA was reduced in both the groups with low and high dosage of BOL, which showed a remarkable difference as compared with that of the model group (low dosage group: 376.15 microg/L+/-35.48 microg/L vs 806.07 microg/L+/-98.49 microg/L P<0.05; high dosage group: 340.14 microg/L+/-30.18 microg/L vs 806.07 microg/L+/-98.49 microg/L P<0.05). The LN content of low and high dosage group of BOL was lower than that of model group (low dosage group: 71.99 microg/L+/-8.15 microg/L vs 133.94 microg/L+/-14.45 microg/L P <0.01; high dosage group: 71.68 microg/L+/-11.62 microg/L vs 133.94 microg/L+/-14.45 microg/L P<0.01) and colchicine group (low dosage group: 71.99 microg/L+/-8.15 microg/L vs 118.28 microg/L+/-16.13 microg/L P < 0.05; high dosage group: 71.68 microg/L+/-11.62 microg/L vs 118.28 microg/L+/-16.13 microg/L P <0.05). Examined by Ridit, BOL could reduce the degeneration and necrosis of liver cells (chi(2)=11.99 P<0.05), the degree of fibre hyperplasia (chi(2)=13.24 P<0.05) and the pathological change of ultra micro-structure as well. CONCLUSION: The BOL has certain therapeutic effect on the experiment hepatofibrosis. Its mechanisms might include: protecting the function of liver cells, inhibiting excessive synthesis and secretion of extracellular matrix from hepatic stellate cells, relieving the capillarization of hepatic sinusoid, improving liver micro-circulation, and regulating immune function.

Animals↗

PubMed2001

Interleukin-18 expression induced by Epstein-Barr virus-infected cells.

Human Epstein-Barr virus (EBV)-negative Burkitt lymphomas cells usually grow as malignant subcutaneous tumors in athymic mice, but these tumors regress when the Burkitt cells are injected in conjunction with EBV-positive lymphoblastoid cells or when the Burkitt cells are transfected with the EBV latent membrane protein-1 (LMP-1) gene. Tumor regression is mediated, in part, by murine interferon gamma (IFN-gamma) and the IFN-gamma-induced murine chemokine IFN-gamma-inducible protein-10 (IP-10). The mechanisms by which EBV-LMP-1 promotes the expression of IFN-gamma has remained unclear. Here we show that murine interleukin (IL)-18 was consistently expressed in regressing Burkitt tumors but was either expressed at low levels or absent from progressively growing Burkitt tumors. By immunohistochemical methods, IL-18 protein was visualized in regressing but not in progressively growing Burkitt tumors. In contrast, IL-12 p35 and IL-12 p40 were only rarely expressed in regressing Burkitt tumors. In splenocyte cultures, EBV-infected lymphoblastoid cells and LMP-1-transfected Burkitt cells promoted the expression of IL-18 but not the expression of IL-12 p35 and IL-12 p40. A neutralizing antibody directed at murine IL-18 reduced murine IP-10 expression induced by EBV-immortalized cells in splenocyte cultures. These results provide evidence for IL-18 expression in response to a viral latency protein and suggest that IL-18 may play an important role as an endogenous inducer of IFN-gamma expression, thereby contributing to tumor regression.

Animals↗

PubMed2001

Dopamine D2 receptor inhibition of adenylyl cyclase is abolished by acute ethanol but restored after chronic ethanol exposure (tolerance).

Dopamine D2 (D2) receptors seem to mediate reinforcing responses to addicting drugs. A stably transfected NG108-15 cell line expressing the long form of the rat brain D2 receptor (D2L) was used to determine how ethanol modifies D2 receptor coupling to adenylyl cyclase. Activation of D2L receptors by the D2 receptor-specific agonist R-(-)-2,10,11-trihydroxy-N-propylnorapomorphine hydrobromide (NPA) inhibits both basal and receptor-stimulated cAMP production in these cells. Ethanol added acutely prevents D2L receptor inhibition of cAMP production. After chronic exposure to ethanol, however, D2L receptor coupling to adenylyl cyclase becomes tolerant to rechallenge with ethanol, i.e., ethanol no longer inhibits D2L receptor coupling and NPA inhibition of cAMP production is restored. Acute ethanol does not change NPA binding to D2 receptor in cell membranes but abolishes guanosine-5'-O-(3-thio)triphosphate induction of a lower-affinity state; chronic ethanol is without effect. The protein kinase A (PKA) inhibitor adenosine 3',5' cyclic monophosphorothioate, Rp-isomer, prevents acute ethanol inhibition of D2L receptor coupling. In contrast, the PKA activator adenosine 3',5' cyclic monophosphorothioate, Sp-isomer, reverses chronic ethanol-induced tolerance of D2L receptor coupling, restoring coupling to an ethanol-sensitive state. These results suggest that D2L receptor coupling to adenylyl cyclase via G(i) develops tolerance to ethanol inhibition, which appears to be influenced by PKA activity.

Adenylyl Cyclase Inhibitors↗

PubMed2001

[NIES-90 microcystin producing algae strain genome library construction and one isolated gene analysis].

OBJECTIVE: To construct a plasmid microcystis genome library for microcystin (MC) pertaining gene family screening or microcystis strain specific gene screening. METHODS: Extracting genome DNA from MC producing strain NIES-90, then digesting DNA by HindIII and ligating to CIPase treated pUC18/HindIII fragment which later transformed to JM109. After checking the library by Xgal/Antibiotics plate, clones isolation, a few clones were sequenced and specific primers synthesized; finally, PCR was used to testify clone's NIES-90 strain specificity. RESULTS: Successfully constructed a NIES-90 genome plasmid library with following functions: a) cloning efficiency more than 95% by comparing the white/blue clones ratio in Xgal Plate; b) 200-700 bp average insert length with 3 x 10(5) independent clones by independent clones analysis; c) 10 times more coverage of original NIES-90 genome; d) strong strain specificity by cross PCR analysis of some clone's sequence in two different microcystis strains compared with FACHB-469. CONCLUSION: We successfully constructed a NIES-90 MC producing microcystis strain's genome plasmid library which could be used for screening MC pertaining gene family because of high strain specificity of some clones.

DNA, Plant↗

PubMed2001

Detection of p53 gene mutations in sputum samples and their implications in the early diagnosis of lung cancer in suspicious patients.

OBJECTIVES: To evaluate the value of detecting p53 gene point mutations in sputum samples and its validity and reliability as a surveillance index in the early diagnosis of lung cancer in suspicious patients. METHODS: Sputum samples were collected from 54 cases identified as lung cancer and 114 cases identified as pulmonary benign disease. The polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) was performed for the detection of point mutations at exons 5-8 of the p53 gene, and sputum smears were also used for each sample. RESULTS: The detected mutation rate of 55.56% (30/54) in the lung cancer group was significantly higher than that of 1.75% (2/114) in the control group (P < 0.001). In the lung cancer group, the sensitivity, specificity, and positive likelihood ratio (PLR) of p53 mutations as a diagnostic marker for lung cancer were 55.56%, 98.25% and 31.75%, respectively. Also, the detection rates were 35.19% (19/54) by smears and 55.56% (30/54) by PCR-SSCP-silver stain, respectively. The differences both in rate and consistency were statistically significant (P < 0.01 and P < 0.05, respectively). Moreover, statistical analysis showed no significant relations between p53 mutations and clinical parameters such as gender, smoking habits, histotypes and stages, but the detection rate of p53 mutations in older patients (> or = 60 years old) was significantly higher than that in younger patients (P = 0.02). One case with p53 mutations at exon 5 in the control group was confirmed to be squamous cell carcinoma after 4 years of follow-up. CONCLUSION: Detection of p53 gene alterations in sputum samples by PCR-SSCP-silver stain can be used as a follow-up surveillance index for the early diagnosis of lung cancer in suspicious patients.

Adult↗

PubMed2001

[Detection of p53 gene alteration in sputum sample and its implications in early diagnosis of lung cancer].

OBJECTIVES: To evaluate the value of detecting point mutation of p53 gene in sputum sample and its validity and reliability as a surveillance index in early diagnosis of lung cancer in suspicious patients. METHODS: Sputum samples were collected from 54 cases identified as lung cancer and 114 cases as pulmonary benign disease. The polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) was performed for detection of point mutation at exon 5 - 8 of p53 gene and sputum smear also used for each sample. RESULTS: A detection rate of 55.56% (30/54) in the lung cancer group is significantly higher than that of 1.75% (2/114) in the control (P < 0.001). In the lung cancer group, the sensitivity, specificity, and positive likelihood ratio of p53 alterations as a diagnostic marker of lung cancer were 55.56%, 98.25% and 31.75 respectively. Moreover, the detection rates were 35.19% (19/54) by smears and 55.56% (30/54) by PCR-SSCP-silver stain; both the difference and consistency were statistically significant (P < 0.01 and P < 0.05 respectively). Statistic analysis did not show any significant relation between p53 alteration and clinical parameters such as gender, smoking habits, histotypes and stages, but the detection rate of p53 alteration in older patients (>or=60 years old) was significantly higher than that in younger (P = 0.02). One case with p53 alteration at exon 5 in the control group was confirmed to be squamous carcinoma after 4 years of follow-up. CONCLUSION: Detection of p53 gene alteration in sputum sample by PCR-SSCP-silver stain can be used as a follow-up surveillance index for early diagnosis of lung cancer in suspicious patients.

Adult↗

PubMed2001

[Correlation of tumor microvessel density with prognosis in laryngopharyngeal malignant melanoma].

OBJECTIVE: To investigate the relationship between microvessel density and clinicopathology, as well as the prognosis in pharyngo-laryngeal malignant melanoma. METHODS: Specific endothelial cell markers with immunohistochemistry and microvessel density with morphometry in 28 cases of laryngopharyngeal malignant melanoma. RESULTS: There was no correlation between the microvessel density (MVD) and the tumor size, Clark grade, as well as Breslow grade; however, significant correlation was found between the MVD and the AJC's grade, as well as the proliferating cell nuclear antigen (PCNA) labelling index. Microvessel counts were associated with overall survival by Kaplan-Meier analysis. An average vessel count of less than 36.5 (x 200) suggested a better survival, but a higher vessel count of more than 36.5 (x 200) showed a trend to worse the overall survival. CONCLUSION: The results suggest a significant relationship between MVD and prognosis; moreover, MVD may be a useful prognostic indicator in laryngopharyngeal malignant melanoma.

Adult↗

PubMed2000

Unusual renal features of Lowe syndrome in a mildly affected boy.

The oculocerebrorenal syndrome of Lowe (OCRL) is an X-linked disorder characterized by congenital cataracts, mental retardation, and renal tubular dysfunction. The gene responsible for OCRL was identified by positional cloning and encodes a lipid phosphatase, phosphatidylinositol 4,5, bisphosphate [PtdIns(4,5)P2]5-phosphatase, which localizes to the Golgi apparatus and is suspected to play a role in Golgi vesicular transport [Suchy et al., 1995]. In addition to the ocular and renal manifestations, most boys with OCRL have cognitive problems and maladaptive behaviors including tantrums and stereotypies. We report a boy with a history of congenital cataracts and mild developmental delay who was also found to have hematuria with proteinuria but minimal signs of renal tubular dysfunction. Subsequent renal biopsy was compatible with a diagnosis of a noncomplement fixating chronic glomerulonephritis. Despite the atypical renal findings, skin fibroblast analysis for PtdIns (4,5)P2 5-phosphatase was performed, and enzyme activity was low, consistent with the diagnosis of OCRL. Western blot analysis from cell lysates showed the ocrl protein was decreased in size and amount. Our report shows atypical renal features of OCRL in a mildly affected boy. The possibility of OCRL should be considered in boys with cataracts and glomerular disease, even in the absence of renal tubular defects and frank mental retardation usually associated with the syndrome. Am. J. Med. Genet. 95:461-466, 2000. Published Wiley-Liss, Inc.

Acidosis, Renal Tubular↗

PubMed2000

Human glioma cell BT325 expresses a proteinase that converts human plasminogen to kringle 1-5-containing fragments.

Angiostatin, a specific angiogenesis inhibitor, is an internal fragment of plasminogen, and can be generated in many systems mediated by different enzymes in vitro. The mechanism of angiostatin generation in vivo has not been well defined. Here we demonstrated that human glioma cell line BT325 can express an enzyme that can convert purified plasminogen to angiostatin-like fragments with molecular masses of 65, 60, and 58 kDa, respectively. These fragments have an identical N-terminal as KVYLS, which starts from Lys(98) of the plasminogen precusor. According to their molecular mass, the three fragments should comprise kringle domain 1 to kringle domain 5 (kringle 1-5). The proteolytic fragments obtained as above can inhibit the growth of bovine aortic endothelial (BAE) cells specifically. The proteolysis process can be completely inhibited by serine proteinase inhibitors, and partially inhibited by EDTA. The molecular weight of the peptide, which contains an enzymatic activity responsible for the proteolysis, was 13 kD determined by gel filtration and SDS-PAGE. The present data suggest that glioma cell BT325 can produce a novel proteinase to generate kringle 1-5 of plasminogen as an angiogenesis inhibitor.

Amino Acid Sequence↗

PubMed2000

Interleukin 21 and its receptor are involved in NK cell expansion and regulation of lymphocyte function.

Cytokines are important in the regulation of haematopoiesis and immune responses, and can influence lymphocyte development. Here we have identified a class I cytokine receptor that is selectively expressed in lymphoid tissues and is capable of signal transduction. The full-length receptor was expressed in BaF3 cells, which created a functional assay for ligand detection and cloning. Conditioned media from activated human CD3+ T cells supported proliferation of the assay cell line. We constructed a complementary DNA expression library from activated human CD3+ T cells, and identified a cytokine with a four-helix-bundle structure using functional cloning. This cytokine is most closely related to IL2 and IL15, and has been designated IL21 with the receptor designated IL21 R. In vitro assays suggest that IL21 has a role in the proliferation and maturation of natural killer (NK) cell populations from bone marrow, in the proliferation of mature B-cell populations co-stimulated with anti-CD40, and in the proliferation of T cells co-stimulated with anti-CD3.

Amino Acid Sequence↗

PubMed2000

Effective targeting of tumor vasculature by the angiogenesis inhibitors vasostatin and interleukin-12.

Solid tumors are dependent on preexisting vasculature and neovascularization for their growth. Successful cancer therapies targeting the tumor vasculature would be expected to block the existing tumor blood supply and to prevent tumor neovascularization. We tested the antitumor activity of experimental therapy with 2 distinct antiangiogenic drugs. Vasostatin inhibits endothelial cell growth and neovascularization, and interleukin-12 (IL-12) targets the tumor vasculature acting through interferon-gamma (IFN-gamma) and the downstream chemokines interferon-inducible protein-10 (IP-10) and monokine induced by IFN-gamma. Individually, vasostatin and IL-12 produced distinct efficacy profiles in trials aimed at reducing tumor growth in athymic mice. In combination, these inhibitors halted the growth of human Burkitt lymphoma, colon carcinoma, and ovarian carcinoma. Thus, cancer therapy that combines distinct inhibitors of angiogenesis is a novel, effective strategy for the experimental treatment of cancer. (Blood. 2000;96:1900-1905)

Angiogenesis Inhibitors↗

PubMed2000

Alteration in left ventricular diastolic filling and accumulation of myocardial collagen at insulin-resistant prediabetic stage of a type II diabetic rat model.

BACKGROUND: Considerable controversy exists regarding impairment of cardiac function in diabetes mellitus (DM). We investigated the serial changes in left ventricular (LV) histopathology and LV filling dynamics in Otsuka Long-Evans Tokushima Fatty (OLETF) rats, which have been established as an animal model of type II DM. METHODS AND RESULTS: In 54 OLETF and 54 non-DM rats, body weight, blood pressure, heart rate, and transmitral pulsed Doppler examinations were performed from 5 to 47 weeks of age. An oral glucose tolerance test was performed at 10, 20, and 30 weeks of age. The hearts were excised for histopathology, including immunohistochemistry and histomorphometry of collagen, and measurement of hydroxyproline at baseline and each stage of developing DM. In the prediabetic stage (15 weeks of age), in which fast blood glucose remained normal, OLETF rats manifested mild obesity, postprandial hyperglycemia, and hyperinsulinemia, and early diastolic transmitral inflow exhibited prolonged deceleration time (OLETF, 59+/-10 ms versus non-DM, 49+/-8 ms, P<0.01) and low peak velocity (OLETF, 73+/-11 cm/s versus non-DM, 88+/-11 cm/s, P<0.01). Histopathology revealed extracellular fibrosis and abundant transforming growth factor-beta(1) receptor II in LV myocytes of OLETF rats. At 15 weeks of age, the ratio of collagen area/visual field of LV wall in OLETF rats (8.3+/-1.3%) was larger than that in non-DM rats (4.9+/-1.8%, P<0.0001), and the collagen content/dry tissue weight ratio of heart was significantly higher in OLETF (2. 0+/-0.5 mg/g) than non-DM (1.3+/-0.2 mg/g, P<0.01) rats. CONCLUSIONS: A metabolic abnormality present in the prestage of type II DM may produce LV fibrosis and alteration in cardiac function.

Animals↗

PubMed2000

Use of a 13C tracer to quantify the plasma appearance of a physiological dose of lutein in humans.

Increased intake of lutein from vegetables promotes increased density of the macular pigment and therefore may protect against age-related macular degeneration. Our objective was to use a 13C tracer and high-precision gas chromatography-combustion interfaced-isotope ratio mass spectrometry (GC-C-IRMS) to investigate metabolism of a lutein dose equivalent to that absorbed from vegetables. Biosynthetic per-labeled (>99% 13C) lutein was purified from a commercially available extract of algal biomass. Subjects (n = 4) ingested 3 mg of [13C]lutein with a standardized low-carotenoid breakfast. Blood samples were collected at baseline and then hourly for 12 h; additional blood samples were drawn at 16, 24, 48, 72, 96, 192, 360, and 528 h. To produce perhydro-beta-carotene suitable for analysis by GC-C-IRMS, the plasma lutein fraction was hydrogenated on palladium-on-carbon catalyst with acid-catalyzed hydrogenolysis. The stable carbon isotope (13C/12C) ratio measured by GC-C-IRMS was used to calculate the plasma concentration of [13C]lutein. There was a rapid increase in [13C]lutein in plasma until peak enrichment at 16 h followed by a decline to the next measurement at 24 h. At 528 h, small changes in 13C enrichment from baseline could still be measured in plasma lutein. High-precision GC-C-IRMS enables complete definition of the appearance and disappearance of [13C]lutein in plasma after ingestion of a dose similar to that absorbed from foods.

Adult↗

PubMed2000

A comparison of lycopene and astaxanthin absorption from corn oil and olive oil emulsions.

The effect of different oils on the absorption of carotenoids was investigated in mesenteric lymph duct cannulated rats. Sixteen treatment emulsions containing increasing concentrations of either lycopene (LYC) or astaxanthin (AST) (5, 10, 15, 20 micromol/L) were prepared with olive oil or corn oil and continuously infused into the duodenum of the rat. Absorption of carotenoids into the mesenteric lymph duct was determined. Absorption of LYC and AST from both oils increased with the amount infused into the duodenum. The average recovery of AST in the lymph from the olive oil emulsion was 20% but was decreased to 13% from emulsions containing corn oil. Lycopene was not as well absorbed as AST. The average recovery of LYC was 6% from olive oil emulsions but only 2.5% when infused with corn oil. The LYC used in this study was isolated from tomato paste and was primarily in the all-trans form. We did not observe any significant isomerization of all-trans LYC to 9-cis LYC during absorption. We conclude that the type of oil with which a carotenoid is consumed can influence its absorption.

Animals↗

PubMed2000

Improving the quality of care through routine teleradiology consultation.

RATIONALE AND OBJECTIVES: The hypotheses of this study were as follows: (a) University subspecialty radiologists can provide consultations effectively to general radiologists as part of routine clinical operations; (b) these consultations will improve the quality of the final radiologic report; and (c) the consultations will improve the care process and may save money, as well. MATERIALS AND METHODS: For 2,012 consecutive computed tomographic or magnetic resonance (MR) imaging studies, the initial interpretations provided by radiology generalists were subsequently reviewed by specialists, with a final consensus report available. "Truth" was established by final consensus reports. To control for potential bias, 150 adult MR imaging and 250 pediatric radiologic studies were interpreted initially by specialists and then by generalists. Again, truth was established by final consensus reports. RESULTS: There was disagreement between generalist and specialist radiologist interpretations in 427 (21.2%) of the cases reviewed. These disagreements were stratified further by independent specialists, who graded them as important, very important, or unimportant. Differences were considered important or very important in 99% of the cases reviewed. CONCLUSION: Consultations by subspecialty radiologists improved the quality of the radiology reports studied and, at least in some cases, improved the process of care by eliminating unnecessary procedures or suggesting more specific follow-up examinations. The consultation services can be provided cost-effectively from the payer's perspective and may save additional costs when unnecessary procedures can be eliminated.

Humans↗

PubMed2000

Imaging the microcirculatory proton fraction of muscle with diffusion-weighted echo-planar imaging.

RATIONALE AND OBJECTIVES: The diagnosis of exertional compartment syndrome is challenging. In this feasibility study, diffusion-weighted echo-planar magnetic resonance imaging was performed in human subjects to determine whether alterations in the circulating blood volume of muscle secondary to exercise or changes in compartment pressure could be visualized. MATERIALS AND METHODS: The calf muscles of six subjects were studied before and after exercise and also during the application of external pressure to the calf. Gated, single-shot, diffusion-weighted echo-planar imaging (1.5 T) was implemented with signal averaging. Parametric images of the "perfusion" fraction (f) were generated, and regions of interest from anatomic compartments were analyzed. The precision of f was estimated by using propagation of error analysis. RESULTS: Parametric images depicted visible increases in the microcirculatory proton fraction (f) of calf muscle after exercise (mean change, +0.016) and visible decreases in f on the application of 40 mm Hg to the calf after exercise (mean change, -0.023). Mean changes in f were only significantly different from zero for the group, however, under conditions of applied pressure to the calf after exercise. Changes in f were not significantly different across muscle compartments. The error variance in f was approximately 0.01. CONCLUSION: Parametric images of f generated by diffusion-weighted echo-planar imaging may depict alterations in the circulating blood volume of muscle induced by exercise and changes in compartment pressure. The inherent imprecision of this technique, however, appears to limit its clinical utility.

Adult↗