Search PubMed⌕ Search

Biomedical subjects

Lili Wang

Publications and source records attributed to Lili Wang.

83 records · Page 5Linked to original sources
PubMed2002

Novel adeno-associated viruses from rhesus monkeys as vectors for human gene therapy.

Tissues from rhesus monkeys were screened by PCR for the presence of sequences homologous to known adeno-associated virus (AAV) serotypes 1-6. DNA spanning entire rep-cap ORFs from two novel AAVs, called AAV7 and AAV8, were isolated. Sequence comparisons among these and previously described AAVs revealed the greatest divergence in capsid proteins. AAV7 and AAV8 were not neutralized by heterologous antisera raised to the other serotypes. Neutralizing antibodies to AAV7 and AAV8 were rare in human serum and, when present, were low in activity. Vectors formed with capsids from AAV7 and AAV8 were generated by using rep and inverted terminal repeats (ITRs) from AAV2 and were compared with similarly constructed vectors made from capsids of AAV1, AAV2, and AAV5. Murine models of skeletal muscle and liver-directed gene transfer were used to evaluate relative vector performance. AAV7 vectors demonstrated efficiencies of transgene expression in skeletal muscle equivalent to that observed with AAV1, the most efficient known serotype for this application. In liver, transgene expression was 10- to 100-fold higher with AAV8 than observed with other serotypes. This improved efficiency correlated with increased persistence of vector DNA and higher number of transduced hepatocytes. The efficiency of AAV8 vector for liver-directed gene transfer of factor IX was not impacted by preimmunization with the other AAV serotypes. Vectors based on these novel, nonhuman primate AAVs should be considered for human gene therapy because of low reactivity to antibodies directed to human AAVs and because gene transfer efficiency in muscle was similar to that obtained with the best known serotype, whereas, in liver, gene transfer was substantially higher than previously described.

Amino Acid Sequence↗
PubMed2002

Chronic suppression of heart-failure progression by a pseudophosphorylated mutant of phospholamban via in vivo cardiac rAAV gene delivery.

The feasibility of gene therapy for cardiomyopathy, heart failure and other chronic cardiac muscle diseases is so far unproven. Here, we developed an in vivo recombinant adeno-associated virus (rAAV) transcoronary delivery system that allows stable, high efficiency and relatively cardiac-selective gene expression. We used rAAV to express a pseudophosphorylated mutant of human phospholamban (PLN), a key regulator of cardiac sarcoplasmic reticulum (SR) Ca(2+) cycling in BIO14.6 cardiomyopathic hamsters. The rAAV/S16EPLN treatment enhanced myocardial SR Ca(2+) uptake and suppressed progressive impairment of left ventricular (LV) systolic function and contractility for 28-30 weeks, thereby protecting cardiac myocytes from cytopathic plasma-membrane disruption. Low LV systolic pressure and deterioration in LV relaxation were also largely prevented by rAAV/S16EPLN treatment. Thus, transcoronary gene transfer of S16EPLN via rAAV vector is a potential therapy for progressive dilated cardiomyopathy and associated heart failure.

Adenosine Triphosphatases↗
PubMed2002

Application of electromodulated fluorescence to the study of the dynamics of single-strand oligonucleotides at modified gold surfaces.

Single-strand oligonucleotides with fluorescein labels were immobilized on modified gold electrodes and the surface fluorescence intensity was measured as a function of the potential applied to the electrode. The potential consisted of a constant and sinusoidal parts. The fluorescence was detected synchronously with the sinusoidal component of the potential. Large variation in the electromodulated fluorescence (EmF) was observed as a function of the constant component of the applied potential. In the potential range -0.2 to +0.2 V (vs Ag/AgCl) the EmF signal was quasi-reversible. A model for surface fluorescence was applied to the analysis of the EmF in this potential range. The model assumed that the adsorption-desorption process and quenching by the metal were the dominant mechanisms responsible for the observed EmF. For constant potential more negative than -0.5 V, the observed EmF response appeared to have a contribution from ssDNA in solution. This interpretation was suggested by comparison to EmF from solutions containing free fluorescein or labeled ssDNA. Large variation in the EmF response was observed for electrodes modified with amine and carboxyl groups. This suggests that electrostatic interactions play a dominant role.

Electrochemistry↗
PubMed2002

Introduction of audio gating to further reduce organ motion in breathing synchronized radiotherapy.

With breathing synchronized radiotherapy (BSRT), a voltage signal derived from an organ displacement detector is usually displayed on the vertical axis whereas the elapsed time is shown on the horizontal axis. The voltage gate window is set on the breathing voltage signal. Whenever the breathing signal falls between the two gate levels, a gate pulse is produced to enable the treatment machine. In this paper a new gating mechanism, audio (or time-sequence) gating, is introduced and is integrated into the existing voltage gating system. The audio gating takes advantage of the repetitive nature of the breathing signal when repetitive audio instruction is given to the patient. The audio gating is aimed at removing the regions of sharp rises and falls in the breathing signal that cannot be removed by the voltage gating. When the breathing signal falls between voltage gate levels as well as between audio-gate levels, the voltage- and audio-gated radiotherapy (ART) system will generate an AND gate pulse. When this gate pulse is received by a linear accelerator, the linear accelerator becomes "enabled" for beam delivery and will deliver the beam when all other interlocks are removed. This paper describes a new gating mechanism and a method of recording beam-on signal, both of which are, configured into a laptop computer. The paper also presents evidence of some clinical advantages achieved with the ART system.

Biophysical Phenomena↗
PubMed2002

Noninvasive gene transfer to the lung for systemic delivery of therapeutic proteins.

This study evaluates the use of vectors based on adeno-associated viruses (AAVs) to noninvasively deliver genes to airway epithelial cells as a means for achieving systemic administration of therapeutic proteins. We intranasally delivered AAV vectors to mice in which the same AAV2 genome encoding a cellular marker was packaged in capsids from AAV1, 2, or 5 (AAV2/1, AAV2/2, or AAV2/5, respectively). Gene expression levels achieved in both airways and alveoli were higher with AAV2/5 than with AAV2/1 and were undetectable with AAV2/2. The same set of vectors encoding a secreted therapeutic protein, erythropoietin (Epo), under the control of a lung-specific promoter (CC10) was intranasally delivered to mice, resulting in polycythemia with the highest levels of serum Epo obtained with AAV2/5 vectors. After a single intranasal administration of this vector, secretion of Epo was documented for 150 days. Similarly, intranasal administration of an AAV2/5-CC10-factor IX vector resulted in secretion of functional recombinant protein in the bloodstream of hemophiliac, factor IX-deficient mice. In addition, we demonstrate successful readministration of AAV2/5 to the lung 5 months after the first delivery of the same vector. In conclusion, we show that intranasal administration of AAV vectors results in efficient gene transfer to the lung only when the vector contains the AAV5 capsid and that this noninvasive route of administration results in sustained secretion of therapeutic proteins in the bloodstream.

Administration, Intranasal↗
PubMed2002

Effect of adenovirus-mediated overexpression of follistatin and extracellular domain of activin receptor type II on gonadotropin secretion in vitro and in vivo.

Activins are dimeric proteins that stimulate the synthesis and secretion of pituitary FSH by interacting with two classes of receptors, type I and type II, to initiate their intracellular signaling cascade. The extracellular domain of type II activin receptor (ActRII-ECD) contains all structural determinants sufficient for high affinity ligand binding. A soluble recombinant ActRII-ECD has been reported to attenuate FSH secretion from cultured rat anterior pituitary cells in response to exogenous activin A or endogenous activin B. Follistatin is a binding protein that acts as an extracellular factor to bind and inactivate activin. We constructed adenoviral vectors able to mediate expression of follistatin 288 (AdexCAFS288) and ActRII-ECD (AdexCAECD) and tested their biological activities both in vitro and in vivo. The data show that adenovirus-mediated overexpression of either ActRII-ECD or follistatin was able to attenuate FSH secretion by cultured rat anterior pituitary cells. However, AdexCAFS288 overexpression of follistatin was more effective than adenovirus-mediated overexpression of ActRII-ECD. In vivo, a single ip injection of AdexCAFS288 induced the expression of high levels of follistatin and resulted in the suppression of serum FSH levels in castrated male rats for up to 12 d postinjection. Infection with AdexCAFS288 had no effect on LH secretion in vitro or in vivo, demonstrating its selectivity. In conclusion, the results demonstrate the effectiveness of adenovirus-mediated overexpression of follistatin and ActRII-ECD to regulate FSH secretion and the potential of using this strategy as a tool to further define the critical role of activin/inhibin/follistatin circuitry in the modulation of the reproductive system.

Activin Receptors, Type II↗
PubMed2002

Frequency-domain measurement of the photodegradation process of fluorescein.

The frequency-domain technique is applied to measure the photodegradation rate of fluorescein in aqueous solutions. The illuminating light is modulated, and the changes in fluorescence from the illuminated region are detected synchronously. A constant flow rate is imposed on the fluorescein solution to control the mass transport of fluorescein into the illuminated region. The fluorescence response is described by a model that assumes that photodegradation occurs from the triplet excited state. The predictions of the model are consistent with the observed variations in the fluorescence response with flow rate, modulation frequency and incident power. We discuss in this article how the dependence of the model parameters on experimental conditions can be used to infer the photodegradation rate as well as some of the details of the photodegradation mechanism. The results are consistent with the known mechanism of photodegradation of fluorescein. The frequency-domain technique gives a photodegradation rate of 53 s(-1) in an air-saturated solution and 37 s(-1) in solutions purged with argon gas.

Journal Article↗
PubMed2002

Effect of substance P released from peripheral nerve ending on endogenous expression of epidermal growth factor and its receptor in wound healing.

OBJECTIVE: To explore the relationship between substance P (SP) released from peripheral nerve endings and the expression of epidermal growth factor (EGF) and epidermal growth factor receptor (EGFR) during wound healing. METHODS: Fifty Wistar rats were randomly divided into 2 groups, injury group and capsaicin group. In the injury group, a full-thickness skin wound on the back of the rat was taken. The wound edge and granulation tissues were taken on the 1st, 3rd, 6th, 9th, 12th days after injury, respectively. In the capsaicin group, capsaicin was injected subcutaneously on the back of the rats to destroy the sensory nerve to prevent the secretion of SP, then a wound and sample was made in the same way. Immunohistochemistry and in situ hybridization were employed to detect the expression of SP, EGF/EGFR, and EGF mRNA/EGFR mRNA in the granulation tissues. RESULTS: In the injury group, immunohistochemical stain of SP and EGF/EGFR was located on the hair follicles and sebaceous glands at the 1st day. And the stain of SP was obvious at the 3rd day in the granulation tissues, then decreased gradually. EGF/EGFR was at low level at the 3rd day, then increased gradually and reached the peak at the 9th day, then declined. In the capsaicin group, the immunohistochemical stain of SP and EGF/EGFR was faint and without obvious change during the wound healing process. The tendency of the EGF mRNA/EGFR mRNA expression was similar to that of EGF/EGFR. CONCLUSIONS: During wound healing, SP may promote the healing process by affecting the expression of EGF/EGFR in the granulation tissues.

Animals↗
PubMed2002

Effect of seawater soaking on explosive cornea injury.

OBJECTIVE: To observe the changes in corneal tissue after explosive corneal injury and the effect of seawater soaking on the healing of cornea after explosive injury with the help of optical microscope. METHODS: Make 10 similar explosive injury models of rabbit's eyeball using 10 adult grey rabbits. For each rabbit, both eyes are artificially injured through explosion; its right eye is the comparison eye and after the injury the left eye is soaked in seawater for 30 minutes. (Conduct slit lamp examinations, fluorescein dyeing, and ultrasonic cornea thickness metering on the corneas at intervals, that is, before the injury, 1, 2, 3, 4, 5, 7, 9, 12, 15 days after the injury respectively. Examine the corneas under the optical microscope and make comparisons. RESULTS: The corneal thickness of the experiment eye becomes apparently thicker than that of the comparison eye after the injury. The corneal clouding of the former apparently aggravates compared with the latter. The healing of corneal epithelium in the injured eye is slower compared with that in the comparison eye. Comparative examination under the optical microscope shows: after the injury, the corneal tissue of the experiment eye changes distinctly, its healing is delayed and the vascularization degree becomes high in corneal stroma. CONCLUSION: Scars and vascularization of various degrees will appear in corneal stroma after explosive injuries. Seawater soaking will have bad effects on the healing of the cornea injured in explosions.

Animals↗
PubMedDate not supplied

A multistate model for the fluorescence response of R-phycoerythrin.

Although strong fluorescence makes the R-phycoerythrin (R-PE) proteins increasingly useful in biological and clinical assays, they are subject to nonlinear effects including transitions to collective dark states and photodegradation, which complicate quantitative applications. We report measurements of R-PE fluorescence intensity as a function of incident power, duration of illumination and temperature. Emission intensity in the band at 570 nm is proportional to incident power for low power levels. At higher incident power, the emission at 570 nm is smaller than expected from a linear dependence on power. We propose that R-PE undergoes both reversible emission cessation on a millisecond time scale attributed to transitions to a collective dark state, and irreversible photodegradation on a time scale of minutes. Singlet oxygen scavengers such as dithiothreitol and n-propyl gallate have protective effects against the latter effect but not the former. Electrophoretic analysis of irradiated solutions of R-PE indicates that significant noncovalent aggregation is correlated with photodegradation. A multistate model based on fluorescence measurements and geometric analysis is proposed for the fluorophores in R-PE. The phycobilin fluorophores are partitioned into three groups: the phycourobilins (PUB) absorbing at 490 nm, one group of phycoerythobilins (PEB) absorbing at 530 nm (PEB-530) and another group of PEB absorbing at 560 nm (PEB-560). The two processes that result in the loss of fluorescence intensity are most likely associated with the PEB-560 group.

Fluorescence↗