Biomedical subjects

Feng Mao

Publications and source records attributed to Feng Mao.

6 recordsLinked to original sources

PubMed2005

Synthetic erythropoietic proteins: tuning biological performance by site-specific polymer attachment.

Chemical synthesis in combination with precision polymer modification allows the systematic exploration of the effect of protein properties, such as charge and hydrodynamic radius, on potency using defined, homogeneous conjugates. A series of polymer-modified synthetic erythropoiesis proteins were constructed that had a polypeptide chain similar to the amino acid sequence of human erythropoietin but differed significantly in the number and type of attached polymers. The analogs differed in charge from +5 to -26 at neutral pH and varied in molecular weight from 30 to 54 kDa. All were active in an in vitro cell proliferation assay. However, in vivo potency was found to be strongly dependent on overall charge and size. The trends observed in this study may serve as starting points for the construction of more potent synthetic EPO analogs in the future.

Amino Acid Sequence↗

PubMed2004

Resistance index in differential diagnosis of liver lesions by color doppler ultrasonography.

AIM: To investigate the specific value of resistance index (RI) in color Doppler ultrasonography in the diagnosis of focal hepatic lesions. METHODS: Eight hundred patients with 893 hepatic solid lesions were studied with color Doppler flow imaging (CDFI) and pulsed Doppler, including 644 malignant cases (596 primary malignant liver tumors, and 48 metastatic liver tumors), 156 benign cases. All were confirmed by operation and pathology. RESULTS: The detection rate of arterial flow in malignant tumors was 92%, and 52% in benign lesions. Doppler spectrum analysis showed that the resistance index in primary malignant tumors was 0.75+/-0.12, 0.73+/-0.09 in metastatic tumors, and was below 0.6 in benign lesions. The difference was significant (P<0.001). This difference was related with its histopathologic structure. CONCLUSION: The arterial flow with RI > or =0.6 identified by CDFI within the liver lesion can be regarded as a criterion of malignant tumors, RI<0.6 can be regarded as benign disorders. RI is useful in differential diagnosis of liver neoplasms.

Adolescent↗

PubMed2003

Design and chemical synthesis of a homogeneous polymer-modified erythropoiesis protein.

We report the design and total chemical synthesis of "synthetic erythropoiesis protein" (SEP), a 51-kilodalton protein-polymer construct consisting of a 166-amino-acid polypeptide chain and two covalently attached, branched, and monodisperse polymer moieties that are negatively charged. The ability to control the chemistry allowed us to synthesize a macromolecule of precisely defined covalent structure. SEP was homogeneous as shown by high-resolution analytical techniques, with a mass of 50,825 +/-10 daltons by electrospray mass spectrometry, and with a pI of 5.0. In cell and animal assays for erythropoiesis, SEP displayed potent biological activity and had significantly prolonged duration of action in vivo. These chemical methods are a powerful tool in the rational design of protein constructs with potential therapeutic applications.

Amino Acid Sequence↗

PubMed2003

Theoretical calculation and experimental study on the third-order nonlinearity parameter C/A for organic liquids and biological fluids.

In the present paper we deal with calculating and measuring the third-order nonlinearity parameter C/A for organic liquids and biological fluids. For the organic liquids, the second-order derivative of sound speed with respect to pressure at constant entropy is discussed in terms of thermodynamic parameters, and a formula for calculating C/A is established. Calculated results of C/A for various organic liquids demonstrate that omitting the second-order derivative of sound speed with respect to sound pressure in an isentropic process, could overestimate the value of C/A about 20%-30%. For measuring C/A, the finite-amplitude insert substitution technique is employed. A theoretical description of the sound pressure amplitude for the third-order harmonics is obtained using the perturbation method, in which the sound pressure amplitude of the third-order harmonics is shown approximately as a parabolic function of the propagation distance in the medium. By measuring and comparing the sound pressure amplitudes of the third-order harmonics when inserting a test sample, the reference liquid, and a comparative liquid, respectively, the value of C/A for the sample liquid is determined with reference to known C/A values of reference and comparative liquids. An experimental setup is developed, and the measured values of C/A for the organic liquids agree with the predicted ones calculated by the thermodynamic methods. Furthermore, the finite-amplitude method is extended to measure the C/A parameter for biological fluids, and the measured values of C/A for several biological fluids are also presented.

Body Fluids↗

PubMed2003

Characterization of focal hepatic lesions with contrast-enhanced C-cube gray scale ultrasonography.

AIM: To characterize enhancement patterns of focal hepatic lesions using C-cube gray scale sonography with a microbubble contrast agent and to evaluate its usefulness in differential diagnosis of hepatic lesions. METHODS: Fifty-four patients with 58 focal hepatic lesions were examined with Levovist-enhanced C-cube gray scale sonography. The final diagnosis of hepatic lesions was 29 primary liver cancers, 4 metastases, 8 hemangiomas, 12 focal nodular hyperplasias, 2 inflammatory pseudotumors of the liver and 3 angiomyolipomas. The initiation time of enhancement in various lesions and enhancement duration after administration of contrast agent were compared. Vascular findings in lesions were classified as peripheral enhancement, homogenous enhancement, mosaic enhancement and no enhancement depending on microbubble signals in the lesion relative to the liver parenchyma. RESULTS: The initiation time of enhancement in hemangioma (48+/-12 s) was significantly later compared to other lesions (P<0.05). The enhancement duration of malignancies (69+/-33 s in primary liver cancer, 61+/-23 s in metastasis) was significantly shorter compared to benign lesions (P<0.05). Intranodular enhancement appearing at arterial phase and decreasing at portal venous phase was considered characteristic for malignancy. Intranodular enhancement did not appear earlier than the liver parenchyma, and peripheral enhancement pattern was regarded as positive findings for hemangioma. Intranodular enhancement appeared in the arterial phase, and homogenous enhancement pattern sustained in the whole portal venous phase were regarded as positive findings for focal nodular hyperplasia. No microbubble signals appeared in two inflammatory pseudotumors of the liver. CONCLUSION: C-cube gray scale sonography can demonstrate dynamic intranodular enhancement in various focal hepatic lesions. The information provided by this methodology may be useful in the differential diagnosis of hepatic lesions.

Adult↗

PubMed2003

[Treatment of premenopausal patients with advanced or recurrent breast cancer by chemical ablation].

OBJECTIVE: To evaluate the clinical efficacy and safety of luteinizing hormone releasing hormone (LH-RH) analog in premenopausal patients with advanced or recurrent breast cancer. METHODS: LH-RH analog (enantone 3.75 mg/2 ml) were administered to 28 premenopausal patients with advanced recurrent breast cancer and its efficacy and side effect were observed. RESULTS: The response rate (complete response and partial response) was 42.9%, and after 8 weeks of treatment, the plasma estrogen in all patients decreased to the level of postmenopause. No major adverse events were observed. CONCLUSIONS: LH-RH analog is effective and safe for premenopausal breast cancer with low adverse reaction and its administration method is easy.

Adult↗