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Biomedical subjects

F Zhu

Publications and source records attributed to F Zhu.

At least 19 recordsLinked to original sources
PubMed2006

Metabolic consequences of body size and body composition in hemodialysis patients.

Small body mass index is associated with increased mortality in chronic hemodialysis patients. The reasons for this observation are unclear but may be related to body composition. This study aimed to investigate the body composition in chronic hemodialysis patients. The difference between body mass and the sum of muscle, bone, subcutaneous, and visceral adipose tissue masses, measured by whole body magnetic resonance imaging, was defined as the high metabolic rate compartment representing the visceral mass. Protein catabolic rate was calculated from urea kinetics. Forty chronic hemodialysis patients (mean age 54.7 years; 87.5% African Americans; 45% females) were studied. High metabolic rate compartment expressed in percent of body weight was inversely related to body weight (r=-0.475; P=0.002) and body mass index (r=-0.530; P<0.001). In a multiple linear regression model, protein catabolic rate was significantly correlated only with high metabolic rate compartment (r=0.616; P<0.001). Assuming that protein catabolic rate in addition to protein intake reflects urea and uremic toxin generation, it follows that high metabolic rate compartment is the major compartment involved in their generation. Consequently, uremic toxin production rate may be relatively higher in patients with low body weight and low body mass index as compared to their heavier counterparts. The poorer survival observed in smaller dialysis patients may be related to these relative differences.

Adult↗
PubMed2006

Measuring partial body potassium in the arm versus total body potassium.

Skeletal muscle (SM), the body's main structural support, has been implicated in metabolic, physiological, and disease processes in humans. Despite being the largest tissue in the human body, its assessment remains difficult and indirect. However, being metabolically active it contains over 50% of the total body potassium (TBK) pool. We present our preliminary results from a new system for measuring partial body K (PBK) that presently are limited to the arm yet provide a direct and specific measure of the SM. This uniquely specific quantification of the SM mass in the arm, which is shielded from the body during measurement, allows us to simplify the assumptions used in deriving the total SM, thereby possibly improving the modeling of the human body compartments. Preliminary results show that PBK measurements are consistent with those from the TBK previously obtained from the same subjects, thus offering a simpler alternative to computed tomography and magnetic resonance imaging used for the same purposes. The PBK system, which can be set up in a physician's office or bedside in a hospital, is completely passive, safe, and inexpensive; it can be used on immobilized patients, children, pregnant women, or other at-risk populations.

Adult↗
PubMed2006

Application of bioimpedance techniques to peritoneal dialysis.

Peritoneal dialysis (PD) has been used as a home dialysis therapy for renal replacement for more than 30 years. In a recent assessment of treatment quality, the mortality of patients on PD was referenced as being higher than of those on hemodialysis. Several reports suggest that a high proportion of PD patients are overhydrated. Clinical assessment of dry weight in PD patients is difficult and further complicated by the paucity of signs and symptoms indicative of dehydration (such as intradialytic hypotension or muscle cramps). Monitoring tools used for fluid status estimation during hemodialysis, e.g. online blood volume and blood pressure measurement, are not readily available in PD patients. Bioimpedance analysis technique has been considered as a potential tool to measure body fluid non-invasively, inexpensively and simply. Although Bioimpedance analysis has been used in clinical studies for more than 20 years, the knowledge of the electrical properties of body tissues is still evolving. In this review we aim to clarify the principles of different bioimpedance techniques and to introduce their applications in PD patients.

Body Composition↗
PubMed2006

Human platelet alloantigen systems in three Chinese ethnic populations.

Knowledge of the prevalence of human platelet antigens (HPA) in different populations is important for effective diagnosis and management of immune-mediated platelet disorders. The purpose of this study was to determine HPA gene frequencies in the majority Han ethnic population of China and in ethnic She and Tajik minority populations. Using PCR sequence specific primers, HPA- 1, -2, -3, -4, -5, and -6, we determined genotypes for ethnic Han, She, and Tajik blood donors. HPA gene frequencies for Chinese Han were found to be similar to those of She, reflecting the historic affinities of these two populations. HPA gene frequencies for Tajik were closer to those for Caucasians than to Chinese Han, She, or other Asian populations, reflecting their disparate origin and historic geographic isolation. HPA gene frequencies in these Chinese populations reflect their historic origins. Knowledge of these findings may be used to better understand and treat immune-mediated platelet disorders in these populations.

Antigens, Human Platelet↗
PubMed2005

Segment-specific resistivity improves body fluid volume estimates from bioimpedance spectroscopy in hemodialysis patients.

Discrepancies in body fluid estimates between segmental bioimpedance spectroscopy (SBIS) and gold-standard methods may be due to the use of a uniform value of tissue resistivity to compute extracellular fluid volume (ECV) and intracellular fluid volume (ICV). Discrepancies may also arise from the exclusion of fluid volumes of hands, feet, neck, and head from measurements due to electrode positions. The aim of this study was to define the specific resistivity of various body segments and to use those values for computation of ECV and ICV along with a correction for unmeasured fluid volumes. Twenty-nine maintenance hemodialysis patients (16 men) underwent body composition analysis including whole body MRI, whole body potassium (40K) content, deuterium, and sodium bromide dilution, and segmental and wrist-to-ankle bioimpedance spectroscopy, all performed on the same day before a hemodialysis. Segment-specific resistivity was determined from segmental fat-free mass (FFM; by MRI), hydration status of FFM (by deuterium and sodium bromide), tissue resistance (by SBIS), and segment length. Segmental FFM was higher and extracellular hydration of FFM was lower in men compared with women. Segment-specific resistivity values for arm, trunk, and leg all differed from the uniform resistivity used in traditional SBIS algorithms. Estimates for whole body ECV, ICV, and total body water from SBIS using segmental instead of uniform resistivity values and after adjustment for unmeasured fluid volumes of the body did not differ significantly from gold-standard measures. The uniform tissue resistivity values used in traditional SBIS algorithms result in underestimation of ECV, ICV, and total body water. Use of segmental resistivity values combined with adjustment for body volumes that are neglected by traditional SBIS technique significantly improves estimations of body fluid volume in hemodialysis patients.

Algorithms↗
PubMed2005

Adhesiveness of dental resin-based restorative materials investigated with atomic force microscopy.

This study aimed to show that the polymerization contraction of dental methacrylate-based materials, when used as adhesives on hard substrate, produces voids at the material-substrate interface. This phenomenology is closely related with the nanoleakage and the sealing ability of these materials. One prime/bond system, three restorative composite resins, and one orthodontic bonding system were cured by using mirror-like glass slides as a compliance-free reference substrate. The adhesive surface was analyzed by atomic force microscopy, and the polymerization contraction of bulk material was tested by laser beam-scanning method. Nanoperiodic structure of three-dimensional (3D) images, section analysis, and roughness characteristics (R(a) and R(z)) indicated that polymerization contraction produced voids at the interface. When the adhesive surface was exposed to oral simulating fluids (water, ethanol, and lactic acid solutions), hydrolytic degradation involved some hundreds of nanometers in depth. In visible light-cured (VLC) materials, the interface porosity decreased when an irradiation pause ( approximately 2 min) was carried out during gelation.

Adhesiveness↗
PubMed2005

Proving the concept of a data broker as an emergent alternative to supra-enterprise EPR systems.

Electronic Patient Records systems configured into large enterprise models have become the assumed best route forward. In England, as in several other countries, this has expanded to a major meta-enterprise procurement programme. However, concerns are raised that such systems lack user ownership, and experience from other sectors shows difficulties with large enterprise systems. At a time of great change and once again shifting organizations, is this move simply building large and ponderous edifices with unstable materials? Latest software engineering research is now demonstrating the potential of an alternative model, enabling trusted information brokers to search out in real time at point of use data held in registered local and departmental systems. If successful, this could enable a new and less cumbersome paradigm. The data could move where needed whatever the service configuration. A concept demonstrator has been built set in the context of health and social care in England. It is important for all technological support to the health sector to be reviewed as new technologies emerge so as to identify and exploit new opportunities, and the results of this 3 year project show that the health record information broker route merits further investigative research.

Efficiency, Organizational↗
PubMed2005

ABO, Rh, MNS, Duffy, Kidd,Yt, Scianna, and Colton blood group systems in indigenous Chinese.

The frequencies of selected alleles in the ABO, Rh, MNS, Duffy, Kidd, Yt, Scianna, and Colton blood group systems were determined among four indigenous Chinese ethnic populations: Han, Tajik, She, and Yugu. Genotypes were determined by PCR or PCR with sequence specific primers (PCR-SSP). In the Han population, the frequencies of A1, A2, B, and O1 alleles were 0.189, 0.003, 0.170, and 0.638, respectively, and the O2 allele was not identified. Among D+ Hans, the frequencies of C and c alleles were 0.67 and 0.33 and the frequencies of E and e were 0.22 and 0.78, respectively. Among D- Hans, the frequencies of C and c alleles were 0.23 and 0.77 and the frequencies of E and e were 0.04 and 0.96, respectively. The frequencies of M and N alleles were 0.478 and 0.522 among Hans and 0.655 and 0.345 among Tajiks, respectively. The frequencies of Fya and Fyb alleles were 0.94 and 0.06 among Hans and 0.98 and 0.02 among Shes, respectively. The frequencies of Jka and Jkb alleles were 0.49 and 0.51 among Hans and 0.56 and 0.44 among Shes, respectively. The frequency of the Yta allele was 1.00 among Hans. The frequencies of Yta and Ytb alleles were 0.94 and 0.06 among Tajiks, respectively. The frequency of the Sc1 allele was 1.00 in both Han and Tajik ethnic populations. The frequency of the Coa allele was 1.00 in Han, She, and Tajik ethnic populations.

ABO Blood-Group System↗
PubMed2005

FCGR3B polymorphism in three ethnic Chinese populations.

Fc gamma RIIIb receptor is expressed primarily on neutrophils as three polymorphic antigens (HNA-1a, HNA-1b, and HNA-1c) that are encoded by alleles FCGR3B*1, FCGR3B*2, and FCGR3B*3, respectively. These antigens play an important role in immune neutropenia; their absence predisposes individuals who lack them to life-threatening infections. This study investigated the FCGR3B gene frequencies in three ethnic Chinese populations: Han, She, and Tajik. FCGR3B*1, FCGR3B*2, and FCGR3B*3 were genotyped by PCR using sequence specific primers (PCR-SSP). The results showed the gene frequencies were 0.55 for FCGR3B*1 and 0.45 for FCGR3B*2 in 177 Han individuals, 0.69 for FCGR3B*1 and 0.31 for FCGR3B*2 in 87 She individuals, and 0.35 for FCGR3B*1 and 0.65 for FCGR3B*2 in 99 Tajik individuals, respectively. The FCGR3Bnull genotype was not found, but the FCGR3B*3 allele was identified in only three individuals in the Tajik population. DNA clone and sequencing confirmed that these individuals had the C ==>A mutation at position 266 on exon 3. This study found that the gene frequencies in Han and She ethnic groups were similar to those previously reported in the Asian population, but the FCGR3B allele frequencies in the Tajik population were more similar to that of Caucasians.

Antigens, CD↗
PubMed2004

Adjustment of dry weight in hemodialysis patients using intradialytic continuous multifrequency bioimpedance of the calf.

BACKGROUND: Current concepts of dry weight (DW) prescription are largely based on clinical symptoms because of the difficulty in assessing extracellular fluid volume (ECV) during dialysis. Intradialytic changes in ECV can be recorded as changes in extracellular resistance [Re] by continuous regional calf multifrequency bioimpedance spectroscopy (BIS). We hypothesized that relative changes in calf Re (Re at time '0' over Re at time 't' [R(e-0)/R(e-t)]) will become very small when ECV is reduced towards normal and individual dry weight is reached. METHOD: Intradialytic continuous calf BIS was recorded repeatedly in 15 hemodialysis (HD) patients. The first measurement was performed at the prevailing clinical dry weight (CDW). Next measurements were made after post-HD body weight was gradually decreased by 0.2-0.3 kg per treatment. This procedure was iterated over several subsequent treatments until a treatment was observed where changes in R(e-0)/R(e-t) were < 1%. The weight at the end of this treatment was defined as "achieved dry weight (ADW)". Each R(e-0)/R(e-t) curve was fitted using a Matlab program (curve fitting toolbox) to obtain the exact weight at 20 min after beginning of the flattening of the R(e-0)/R(e-t) slope ('dry' weight estimated from BIS, DW-BIS). RESULTS: Both mean ADW (80.5 +/- 34.1 kg) and mean DW-BIS (80.6 +/- 34.1) were significantly lower than CDW (81.4 +/- 32.0 kg, p < 0.001), but there was no difference between ADW and DW-BIS. However, the average weight reduction from CDW to ADW (0.80 +/- 0.15 kg) was significantly higher than from CDW to DW-BIS (0.66 +/- 0.14 kg, p < 0.001, paired t-test). When ADW was achieved, pre-dialysis systolic blood pressure (SBP) was lower than at CDW (139.3 +/- 32.5 mmHg, vs. 129.4 +/- 33 mmHg, p < 0.05), post-HD SBP did not differ. The incidence of clinical symptoms of underhydration was similar at CDW (15%) and DW-BIS (15%), but higher at ADW (46%). CONCLUSION: Intradialytic continuous calf BIS allows the assessment of changes in extracellular calf resistance as an indicator of changes in extracellular fluid volume. Recording of a continuous R(e-0)/R(e-t) slope during dialysis appears to be a promising new tool for the prediction of dry weight in hemodialysis patients.

Analysis of Variance↗
PubMed2004

Experimental studies of the material properties of the forewing of cicada (Homóptera, Cicàdidae).

Detailed investigations on the structural and mechanical properties of the forewing of the cicada were carried out. Measurement of the structures of the wings showed that the thickness of the membrane of each cell and the diameter of each vein were non-uniform in both the longitudinal and transverse directions, and their means were approximately 12.2 and 133.3 microm, respectively. However, the aspect ratios of the wings and the bodies were quite uniform and were approximately equal to 2.98 and 2.13, respectively. Based on the measured thickness, mass and area of the membranes of the cells, the mean density and the mean area density of the wing were approximately 2.3 g cm(-3) and 2.8x10(-3) g cm(-2), respectively. In addition, the diameters of the veins of the wings, including the diameters of the holes in the vein of the leading edge, were examined. The mechanical properties of the wing were investigated separately by nanoindentation and tensile testing. The results indicated that the mean Young's modulus, hardness and yield stress of the membranes of the wings were approximately 3.7 GPa, 0.2 GPa and 29 MPa, respectively, and the mean Young's modulus and strength of the veins along the direction of the venation of wings were approximately 1.9 GPa and 52 MPa, respectively. Finally, the relevant results were briefly analyzed and discussed, providing a guideline to the biomimetic design of the aerofoil materials of micro air vehicles.

Animals↗
PubMed2001

Molecular dynamics study of aquaporin-1 water channel in a lipid bilayer.

The aquaporin-1 water channel was modeled in a palmitoyl-oleoyl-phosphatidyl-choline lipid bilayer, by means of molecular dynamics simulations. Interaction of the protein with the membrane and inter-monomer interactions were analyzed. Structural features of the channel important for its biological function, including the Asn-Pro-Ala (NPA) motifs, and the diffusion of water molecules into the channels, were investigated. Simulations revealed the formation of single file water inside the channels for certain relative positions of the NPA motifs.

Aquaporin 1↗
PubMed2001

Structure of dental glass-ionomer cements by confocal fluorescence microscopy and stereomicroscopy.

The microstructure of four cements, setting by different mechanisms (acid-base, dual cure, triple cure), was studied. The porosity of unpolymerized materials was detected by stereomicroscopy. After polymerization and storage in water or lactic acid solution, the porosity, filler distribution and gel layer, which was formed at the filler/matrix interface of polymerized materials, were examined by confocal laser microscopy. For this purpose, the specimens were treated with fluorescent dye solution before the test. The results showed that hydrolytic degradation (pH 7) mainly involved the resin matrix, and the acid erosion (pH 3.5) involved the gel layer too. As regards the filler, materials with different setting mechanism released the glass particles in different times. The loss of the filler particles occurred quicker in acid-base setting cements, and slower in triple-cured material.

Fluorescent Dyes↗
PubMed2001

cDNA transfection of amino-terminal fragment of urokinase efficiently inhibits cancer cell invasion and metastasis.

Focusing of urokinase-type plasminogen activator (uPA) to the cell surface via binding to its specific receptor (uPAR, CD87) is critical for tumor invasion and metastasis. Consequently, the inhibition of uPA-uPAR interaction on the cell surface might be a promising anti-invasion and anti-metastasis strategy. We examined the effects of cDNA transfection of the human uPA amino-terminal fragment (ATF) on invasion and metastasis of cancer cells. First, a highly metastatic human lung giant-cell carcinoma cell line (PG), used as the target cell for evaluation of this effect, was demonstrated to express both uPA and uPAR. Then, ATF, which contains an intact uPAR binding site but is catalytically inactive, was designed as an antagonist of uPA-uPAR interaction and was transfected into PG cells. [(3)H]-Thymidine incorporation and cell growth curves indicated that expressed ATF did not affect the proliferation of transfected cells. However, analysis by scanning electron microscopy revealed that ATF changed the host cells from the typical invasive phenotype to a noninvasive one. Correspondingly, the modified Boyden chamber test in vitro showed that ATF expression significantly decreased the invasive capacity of transfected cells. Furthermore, in the spontaneous metastasis model, it was confirmed in vivo that expressed ATF remarkably inhibited lung metastasis of implanted ATF-transfected PG cells. In summary, autocrine ATF could act as an antagonist of uPA-uPAR interaction, and ATF cDNA transfection could efficiently inhibit the invasion and metastasis of the cancer cells. Inhibition of uPA-uPAR interaction on the cell surface might be a promising anti-invasion and anti-metastasis strategy.

Animals↗
PubMed2001

[Experimental study of anti-metastasis effect of urokinase amino-terminal fragment gene on human breast cancer cells].

OBJECTIVE: To explore the suppressive effects of urokinase amino-terminal fragment (ATF) gene on metastatic potential of human breast cancer cell line MCF-7. METHODS: A pcDNA3-ATF plasmid containing ATF cDNA under CMV promotor/enhancer control was constructed and transfected into MCF-7 cells by lipofectin. The expression of of uPA/uPAR and ATF in MCF-7 cells were analyzed by RT-PCR and Western blot. The effect of ATF expression on invasiveness in vitro, tumorigenesis and metastasis in vivo of MCF-7 cell was investigated. RESULTS: MCF-7 cells displayed an overexpression of uPA/uPAR. Expression of ATF was detected after ATF gene-transfection. The invasive capacity of ATF gene-transfected MCF-7 cells was decreased significantly. Although the tumorigenesis was not affected, the in vivo metastasis of ATF gene-transfected MCF-7 cells was remarkably inhibited. CONCLUSION: Suppression of invasiveness and metastasis of ATF-transfected MCF-7 cells is perhaps due to a competitive inhibition of interaction with endogenous uPA/uPAR.

3T3 Cells↗