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Biomedical subjects

Feng Shen

Publications and source records attributed to Feng Shen.

8 recordsLinked to original sources
PubMed2003

Properties of a novel magnetized alginate for magnetic resonance imaging.

Implanting recombinant cells encapsulated in alginate microcapsules to secrete therapeutic proteins has been proven clinically effective in treating several murine models of human diseases. However, once implanted, these microcapsules cannot be assessed without invasive surgery. We now report the preparation and characterization of a novel ferrofluid to render these microcapsules visible with magnetic resonance imaging (MRI). The ferrofluid was prepared as a colloidal iron oxide stabilized in water by alginate. The presence of iron particles in the ferrofluid was verified with chemical titration, dynamic light scattering, and magnetization measurement. The microcapsules fabricated with various concentrations of the ferrofluid in the core, or on the surface of alginate microcapsules, or both, all produced microcapsules with smooth surfaces as shown with light and scanning electron microscopy. However, at the nanoscale level, as revealed with atomic force microscopy, the ferrofluid-fabricated microcapsules demonstrated increased granularity, particularly when the ferrofluid was used to laminate the surface. From the force spectroscopy measurements, these modified microcapsules showed increasing surface rigidity in the following order: traditional alginate < ferrofluid in the core < ferrofluid on the surface. Although the mechanical stability of low-concentration ferrofluid (0.1%) microcapsules was reduced, increasing concentrations, up to 20%, were able to improve stability. When these ferrofluid microcapsules were examined with MRI, their T(2) relaxation time was reduced, thereby producing increased contrast readily detectable with MRI, whereas the traditional alginate microcapsules showed no difference when compared with water. In conclusion, such ferrofluid-enhanced alginate is suitable for fabricating microcapsules that offer the potential for in vivo tracking of implanted microcapsules without invasive surgery.

Alginates↗
PubMed2003

Frequency interference between two mesa-shaped quartz crystal microbalances.

The multichannel quartz crystal microbalance (MQCM) is very attractive for biosensor applications. The principle of the MQCM design involves fabricating arrays of quartz microbalances on a single substrate, and it is important that the individual sensor performance is not influenced by the neighboring devices. Feasible ways to control the coupling of acoustical energy within a MQCM structure are to increase the difference in the resonance frequency between the electroded and unelectroded portions of the substrate; and a practical way to achieve this is to use mesa structures. In this paper, the frequency interference between two mesa-shaped quartz crystal microbalances is investigated using Mindlin's theory. The results show that even a very small mesa height (approximately 5% of the plate thickness) can greatly reduce the frequency interference and more effectively trap the acoustic energy. This allows for a broader design window and higher packing density for MQCM applications.

Biosensing Techniques↗
PubMed2003

Neurotization of oculomotor, trochlear and abducent nerves in skull base surgery.

OBJECTIVE: To anatomically reconstruct the oculomotor nerve, trochlear nerve, and abducent nerve by skull base surgery. METHODS: Seventeen cranial nerves (three oculomotor nerves, eight trochlear nerves and six abducent nerves) were injured and anatomically reconstructed in thirteen skull base operations during a period from 1994 to 2000. Repair techniques included end-to-end neurosuture or fibrin glue adhesion, graft neurosuture or fibrin glue adhesion. The relationships between repair techniques and functional recovery and the related factors were analyzed. RESULTS: Functional recovery began from 3 to 8 months after surgery. During a follow-up period of 4 months to 6 years, complete recovery of function was observed in 6 trochlear nerves (75%) and 4 abducent nerves (67%), while partial functional recovery was observed in the other cranial nerves including 2 trochlear nerves, 2 abducent nerves, and 3 oculomotor nerves. CONCLUSIONS: Complete or partial functional recovery could be expected after anatomical neurotization of an injured oculomotor, trochlear or abducent nerve. Our study demonstrated that, in terms of functional recovery, trochlear and abducent nerves are more responsive than oculomotor nerves, and that end-to-end reconstruction is more efficient than graft reconstruction. These results encourage us to perform reconstruction for a separated cranial nerve as often as possible during skull base surgery.

Abducens Nerve↗
PubMed2002

[The functional and phenotypic analysis of T lymphocytes under stimulation of THANK].

OBJECTIVE: To study the function of THANK in T lymphocyte immune regulation. METHODS: On the basis of THANK gene cloning and expression, isolated T and B lymphocytes were stimulated by purified THANK protein and its function in immune regulation was investigated by (3)HTdR incorperation and flow cytometric analysis. RESULTS: In addition to the costimulation on B cell growth, THANK promoted CD3-mediated T cells proliferation, activated resting peripheral blood T lymphocytes and induced apoptosis and the phenotypic change of activated T lymphocytes. CONCLUSION: THANK is involved in the modulation of T cells phenotype and function.

Antigens, CD↗
PubMed2002

[The effect of postoperative transcatheter hepatic arterial chemoembolization on disease-free survival after hepatectomy for hepatocellular carcinoma].

OBJECTIVE: To evaluate postoperative transcatheter hepatic arterial chemoembolization (TACE) for improving the disease-free survival of HCC patients after hepatectomy. METHODS: 1 725 HCC patients were followed up after hepatectomy retrospectively. Of 1 457 patients who were followed-up completely, 209 had postoperative TACE. The 1 457 patients were divided into ten groups according to tumor thrombus, small HCC, capsular invasion, vascular invasion and cirrhosis. The disease-free survival was analyzed between subgroups of weather postoperative TACE was performed in every group. Software SAS 6.12 and EGRET package were used. Kaplan-Meier estimation was used to calculate the disease-free survival rates. RESULTS: There were no difference of the disease-free survival between the subgroups in no capsular invasion and in no hepatic cirrhosis groups. CONCLUSION: Postoperative TACE is helpful in improving the disease-free survival of HCC patients after hepatectomy except those with integrated tumor envelope or no hepatocirrhosis. It is important to prolong the long-term results of operation.

Adolescent↗
PubMed2002

[Injection of NKG5SV gene to inhibit growth and metastasis of hepatocellular carcinoma].

OBJECTIVE: To study the injection of NKG5SV gene to inhibit growth and metastasis of hepatocellular carcinoma (HCC). METHODS: NKG5SV gene was inserted into retroviral vector pLXSN by normal methods. LacZ gene was used as control. LCI-D20 tumor together with saline, pLXSN-LacZ DNA or pLXSN-NKG5SV was subcutaneously inoculated to the nude mice. Tumor formation rate and tumor size were noted 35 days after inoculation. LCI-D20 tumor was inoculated subcutaneously. Saline, pLXSN-LacZ DNA or pLXSN-NKG5SV was intratumorally injected respectively 10 days after inoculation. Tumor growth was observed 35 days after inoculation. Liver cancer was resected 22 days after intrahepatic inoculation. Saline, pLXSN-LacZ DNA or pLXSN-NKG5SV was respectively injected at incisal margin or intraspleen. Mice were killed 35 days after inoculation to observe tumor recurrence at incisal margin, intrahepatic metastasis and extrahepatic metastasis. RESULTS: Tumor formation rate and tumor diameter(cm) were 1.76 +/- 0.11, 1.51 +/- 0.34, 0.33 +/- 0.04 in the control group, LacZ group, NKG5SV group respectively when tumor and different cDNA were inoculated together. Tumor diameter(cm) and weight(g) were 0.87 +/- 0.08, 0.83 +/- 0.05, 0.26 +/- 0.04; 0.43 +/- 0.06, 0.38 +/- 0.04, 0.08 +/- 0.06 in the control group, LacZ group, NKG5SV group respectively when different cDNA were injected into the LCI-D20 tumor. Sites with extrahepatic metastasis nidi, incisal margin recurrence tumor size(cm), intrahepatic metastasis nidi, metastasis involved hepatic lobes in the control group, LacZ group, NKG5SV group were 4.25 +/- 1.48, 4.25 +/- 1.04, 0.63 +/- 0.51; 1.51 +/- 0.27, 1.35 +/- 0.17, 0.81 +/- 0.17; 2.50 +/- 1.41, 2.38 +/- 1.06, 1.25 +/- 0.71; 2.13 +/- 0.99, 2.00 +/- 0.75, 1.38 +/- 0.74 respectively when NK cells were injected at incise margin. They were 4.38 +/- 1.85, 4.25 +/- 1.48, 1.00 +/- 0.75; 1.13 +/- 0.23, 0.97 +/- 0.29, 0.76 +/- 0.16; 2.50 +/- 1.41, 2.05 +/- 1.12, 0; 2.13 +/- 0.83, 1.75 +/- 0.88, 0 respectively when NK cell were injected intrasplenicly. CONCLUSIONS: NKG5SV gene can inhibit HCC growth and postoperative metastasis and recurrence.

Animals↗