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Biomedical subjects

D Shen

Publications and source records attributed to D Shen.

At least 55 records · Page 3Linked to original sources
PubMed1999

[The effect of hepatitis B virus x protein on cell cycling].

OBJECTIVE: To study the effect of HBx protein on cell cycle progression and its molecular mechanism. METHODS: The eucaryotic expression vector pCEP4 of HBx gene was constructed and introduced into HepG2 cells. The HepG2 cells transfected with X gene (X cell) were synchronized in a quiescent state by culture of serum deprivation. Flow cytometry, immunohistochemical and Western Blot analysis were performed. RESULTS: 70% HepG2 cells transfected with pCEP4 (X0 cells) was induced in G0-G1 phase, only 56% X cells in G0-G1 phase, almost identical to its parental HepG2 cells cultured in serum medium. To further understand the molecular mechanism of cell cycle progression, the p21CIP1/WAF1 and PCNA were examined. HBx was found to strongly increase the level of PCNA in X cells (86 +/- 3)% compared with X0 cells (9 +/- 5)%, and greatly decrease the level of p21CIP1/WAF1 protein in X cells (16 +/- 6)% compared with X0 cells (86 +/- 8)% (P < 0.001). CONCLUSIONS: These data suggest a molecular mechanism by which HBx likely contributes to viral carcinogenesis. By deregulating cell cycle checkpoint control, HBx could participate in the selection of cells that are genetically unstable, some of which would accumulate unrepaired transforming mutations.

Adaptor Proteins, Signal Transducing↗
PubMed1999

[Investigation of the diplopia after intraocular lens implantation].

OBJECTIVE: To investigate the pathogenesis, mechanism and prognosis of diplopia after cataract extraction with intraocular lens implantation (IOL). METHODS: Besides routine ocular examinations, refraction, ocular position, ocular movement, fusional function and image of diplopia were examined on all the patients. Forced duction was examined on partial patients. RESULTS: Among 24 cases with diplopia after IOL implantation, there were 19 cases of binocular diplopia and 5 cases of monocular diplopia. Of the binocular diplopia, there were 17 cases of strabismic diplopia and 2 cases of diplopia due to central fusional impairment. Of the cases with monocular diplopia, there were 4 cases resulted from operative complication and one case with congenital iridocoloboma. CONCLUSIONS: The pathogenesis of strabismic diplopia resulted from dysfunction of ocular movement is unknown. Most of the patients can obtain binocular vision by early active treatment. Monocular diplopia is partly resulted from operative complication.

Adult↗
PubMed1999

[Cloning and sequencing analysis of rice stripe virus genome segment 4 of Chinese isolate Y].

The cDNA fragment covering full-length sequence of RStV RNA4 of Yunnan isolate in China was obtained by RT-PCR. The PCR-derived fragment was then cloned into vector pCRII. The cloned cDNA was sequenced. Comparison of the nucleotide and deduced amino acid sequences with those of the Japanese isolate T was made. The results showed that at the nucleotides level, vORF, vcORF and the intergenic region had 94.9%, 94.1% and 86.1% identity respectively, the 5'-untranslational region was exactly the same as that of Japanese isolate T, while the 3'-terminal sequence had 96.1% identity, differing by two nucleotides; at the amino acid level, vORF and vcORF had 99.4% and 98.3% identity respectively. Therefore, as well as being exactly the same size for the two isolates, the amino acid sequences of the coding regions and the 5'- and 3'-terminal sequences were well conserved. Our results indicated that the Chinese isolate is closely related to the Japanese isolate T.

Amino Acid Sequence↗
PubMed1999

[Isolation and identification of a saponine from Patrinia scabiosaefolia].

A saponine compound was isolated from the acetone extract of the roots and rhizomes of Patrinia scabiosaefolia Fish. ex Link. Its structure was identified by combination of chemical reaction and spectrum analysis as 3-O-alpha-L-rhamnopyranosyl-(1-2)-beta-D-xylopyranosyl oleanolic acid (giganteaside D), and part of its 13C-NMR data was revised by the 2D-NMR. The compound was found in the Patrinia for the first time.

Patrinia↗
PubMed1998

[Relationship between genotype of angiotensin converting enzyme gene and left ventricular hypertrophy in Chinese hypertensives].

OBJECTIVE: To search into the relationship between genotype of angiotensin-converting enzyme (ACE) gene and left ventricular hypertrophy(LVH) in Chinese hypertensives. METHODS: ACE genotyping with polymerase chain reaction (PCR) was performed in 33 unrelated hypertensives with LVH, 55 hypertensives without cardio-cerebrovascular diseases and 62 healthy controls. RESULTS: The frequencies of DD genotype (0.394) and deletion allele (0.606) among hypertensives with LVH were significantly higher than those (0.129 and 0.387) among controls and those (0.128 and 0.400) among hypertensives without cardio-cerebrovascular diseases. CONCLUSION: A deletion polymorphism of ACE gene probably increases the risk for left ventricular hypertrophy in Chinese hypertensives.

Adult↗
PubMed1998

Structure and developmental expression of the mouse RGR opsin gene.

PURPOSE: The aim of this study is to isolate and characterize cDNA clones and the genes that encode mouse RPE retinal G protein-coupled receptor (RGR) and to analyze expression of the RGR gene in the developing mouse retina. The conserved amino acid sequences of RGR from various mammals can be compared to the amino acid sequence motif of G protein-coupled receptors. METHODS: Mouse RGR cDNA and gene clones were isolated from a retina cDNA library and 129SV genomic DNA library, respectively. The expression of RGR in the developing C57BL/6J mouse retina was analyzed by immunohistochemical staining with a polyclonal antipeptide antibody. RESULTS: The deduced amino acid sequence of mouse RGR is 78% and 81% identical to that of bovine and human RGR, respectively. The mouse RGR gene is split into seven exons and extends about 11 kb. Two predominant mRNA transcripts, 1.9 and 1.7 kb in length, and a third, relatively faint, 5.5-kb transcript were detected in mouse eye by hybridization to a RGR cDNA probe. Frozen sections of C57BL/6J mouse retina at various stages of development were incubated with a mouse RGR antipeptide antibody. RGR immunoreactivity was first seen at postnatal day 2 (P2) in centrally located RPE cells. From day P6 to P12, there was an increase in the number and intensity of immunoreactive RPE cells in the central and mid-peripheral regions of the retina, while the most peripheral RPE cells were still negative. By day P16, the length of the RPE monolayer was immunoreactive, and staining of the central RPE cells was markedly more intense than at younger ages. CONCLUSIONS: Mouse and human RGR are highly conserved. A gradient of RGR expression in RPE extends from the central to the peripheral retina during development. In reference to the appearance of melanin-positive differentiated RPE cells, the induction of RGR expression is a relatively late event in the maturation of the retina.

Aging↗
PubMed1998

In vitro studies of a new thrombus-specific ultrasound contrast agent.

Ultrasound is used as a primary diagnostic technique for the detection of deep venous thrombosis. The purpose of this study is to describe the development of a new thrombus-specific ultrasound contrast agent: The linear hexapeptide (lysine-glutamine-alanine-glycine-aspartate-valine) was synthesized and coupled to a lipid moiety. The targeted lipid was then incorporated into the lipid blend for the contrast agent Aerosomes (ImaRx, Tucson, AZ, USA). The lipid blend was used to entrap perfluorobutane microbubbles. The microbubbles were sized and studied in vitro for acoustic stability, binding to blood clot, and ultrasound enhancement in vitro of blood clot. The results showed the mean size of the specific ultrasound contrast agent (MRX-408) was about 2.0 microm. The microbubbles appeared as smooth spherical structures. Microscopy showed that the targeted bubbles bound to blood clot whereas control, nontargeted bubbles did not bind to blood clot. In vitro acoustic study showed similar stability of the microbubbles compared with control microbubbles. The targeted microbubbles enhanced blood clot in vitro whereas nontargeted microbubbles did not enhance clot. Thus this promising new thrombus-specific ultrasound contrast agent could potentially improve detection of thrombosis by ultrasound and might be useful for distinguishing between new and old thrombosis. In vivo studies are in progress.

Contrast Media↗
PubMed1998

[The relationship between angiotensin-converting enzyme gene polymorphism and brain infarction in Chinese hypertensives].

OBJECTIVE: To identify the insertion/deletion(I/D) polymorphism of angiotensin-converting enzyme(ACE) gene in Chinese hypertensives complicated with brain infarction. METHODS: ACE genotyping with polymerase chain reaction(PCR) was performed in 62 unrelated healthy controls, 55 hypertensives without cardio-cerebrovascular diseases and 44 hypertensives complicated with brain infarction (all controls had no hypertension family history, while the cases had hypertension family history). RESULTS: No significant differences could be detected between ACE gene I/D polymorphism and hypertension. However,the frequencies of DD genotype and deletion allele among hypertensives complicated with brain infarction (29.6% vs 56.8%) were higher than those among healthy controls (12.9% vs 38.7%, P<0.05 and P<0.01) and those among hypertensive without cardio-cerebrovascular diseases(12. 8% vs 40%, P<0.05 and P<0.02). CONCLUSION: A deletion polymorphism of ACE gene is probably an important hereditary factor of brain infarction's morbidity in Chinese hypertensives. The detection of ACE genotypes in hypertensives would improve the early diagnosis of brain infarction.

Adult↗
PubMed1998

Cross-resistance to methotrexate and metals in human cisplatin-resistant cell lines results from a pleiotropic defect in accumulation of these compounds associated with reduced plasma membrane binding proteins.

Cross-resistance to a wide array of toxic chemicals is a common phenomenon in cisplatin-resistant cell lines. In this study, two independently isolated cisplatin-resistant cell lines derived from a human hepatoma and a cervical adenocarcinoma were shown to be cross-resistant to methotrexate (MTX) and several metal salts, such as sodium arsenite, sodium arsenate, antimony potassium tartrate, and cadmium chloride. A pleiotropic defect resulting in reduced accumulation of cisplatin, 3[H]MTX, 73As3+, and 73As5+ was found in both cisplatin-resistant cell lines. Analysis by immunoblot, indirect immunofluorescence, and Northern hybridization showed dramatically reduced expression of the folate binding protein that mediates MTX uptake in both human cisplatin-resistant cell lines. By photoaffinity labeling with UV irradiation, specific binding proteins of Mr 230,000 and Mr 48,000 for 73As3+ and Mr 190,000 for 73As5+ were found in enriched plasma membrane of both human cisplatin-sensitive parental cell lines. Expression of these specific binding proteins was decreased in cells selected for cisplatin resistance. A protein band at Mr 36,000 that binds to 73As3+ was overexpressed in both human cisplatin-resistant cell lines. The finding of loss of distinct binding proteins for MTX, arsenate, and arsenite in association with decreased accumulation of these agents in cisplatin-resistant cells suggests a pleiotropic, possibly regulatory, alteration in these cells.

Antineoplastic Agents↗
PubMed1998

Effect of SJAMP on human platelet cytoplasmic Ca2+.

Using the method of dual-wavelength measurement of platelet [Ca2+]i and Fura-2 as the Ca2+ fluorophore probe, we measured the effect of acidic Mucopolysaccharide from Sticopus Japonicus Selenka (SJAMP) on platelet [Ca2+]i. The results showed that the most significant increase in platelets [Ca2+]i was seen when the concentration of SJAMP was 100 micrograms/ml and the elevation of normal platelet [Ca2+]i was 93.96 +/- 10.24 nmol/L (n = 10). In the presence of extracellular Ca2+ (1 mmol/L), the magnitude of platelet [Ca2+]i response to SJAMP was increased and the [Ca2+]i could reach 116.72 +/- 10.66 nmol/L (n = 10). On the other hand, the magnitude of increased platelet [Ca2+]i induced by SJAMP was smaller and the duration of [Ca2+]i reaching the highest level was longer when compared with other platelet aggregation agents. In the mean time, if platelets were first incubated with cyclooxygenase inhibitor, the rise of [Ca2+]i evoked by SJAMP was inhibited. The results indicated that the mechanism of the rise of [Ca2+]i induced by SJAMP might be dependent upon the generation of prostaglandin endoperoxides and(or) TXA2.

Animals↗
PubMed1998

Experimental study on the treatment of diabetes by phloridzin in rats.

Male rats at six weeks of age were divided into 5 groups at random: in group I, the rats with diabetes received 70% pancreatectomy; group II had sham-operation serving as controls; diabetic rats in group III were treated with phloridzin; In group IV rats received sham-operation and phloridzin treatment and group V were phloridzin-treated diabetic rats to be studied after discontinuance of phloridzin. 70 days after surgery, the weights and insulin contents of operated remnant pancreas were markedly higher than the expected value of 30%, reaching 44% (48.2% +/- 15.2%), demonstrating that the remnant pancreas still had capacities of compensatory regeneration and proliferation capacities. Phloridzin-treated diabetic rats completely returned to normal in terms of oral glucose tolerance and insulin sensitivity. Discontinuation of phloridzin treatment in diabetic rats resulted in the recurrence of insulin resistance. These results suggested that normalization of hyperglycemia could ameliorate insulin resistance under diabetic conditions.

Animals↗
PubMed1998

Identification of altered expression of ADP/ATP translocase during cellular senescence in vitro.

In this study, we have used the mRNA differential display technique to investigate the changes in gene expression that occur in the process of cellular aging. A number of cDNAs whose corresponding mRNAs are either increasingly or decreasingly expressed in senescent cells were thereby isolated. Through DNA sequencing, one of these differentially displayed mRNAs was identified as mitochondrial ADP/ATP translocase. The altered expression of ADP/ATP translocase in different stages of senescent fibroblasts was further confirmed by Northern blots and semiquantitative RT-PCR. Our results demonstrate that expression of ADP/ATP translocase is progressively decreased during the process of in vitro cellular senescence. Further analyses with MTT assays indicate that the decreased expression of ADP/ATP translocase in senescent cells is in parallel with the decline of mitochondrial functions, suggesting that altered expression of this important mitochondrial enzyme might play an active role in the process of cellular senescence.

Base Sequence↗
PubMed1998

Association of serum Rituximab (IDEC-C2B8) concentration and anti-tumor response in the treatment of recurrent low-grade or follicular non-Hodgkin's lymphoma.

BACKGROUND: Monoclonal antibodies are being utilized for treatment of patients with low-grade non-Hodgkin's lymphoma as well as other cancers. Results from phase I and II clinical studies has shown that the chimeric monoclonal antibody Rituximab has minimal toxicity and significant therapeutic activity in low grade non-Hodgkin's lymphoma. PATIENTS AND METHODS: We have recently reported on a multicentre pivotal phase III clinical trial involving 166 patients with recurrent low-grade lymphoma who were treated with four infusions of Rituximab. Eighty patients (48%) achieved objective responses including 10 patients (6%) with complete responses. Overall, 126 patients (76%) had a > or = 20% reduction in overall tumor size. The median response duration and time to progression are 11.6 and 13.2 months, respectively. The infusional and long term toxicities were limited. RESULTS: In this report we describe the pharmacokinetic data obtained on these patients. Measurable concentrations of Rituximab were detected in all patients after the first infusion and increased throughout the treatment course. The half-life of the monoclonal antibody increased from 76.3 hours after the first infusion to 205.8 hours after the fourth infusion and was concomitant with a four-fold decrease in the antibody clearance. At three months and six months post-treatment, the median Rituximab serum levels were 20.3 micrograms/ml (range 0.0 to 96.8 micrograms/ml in 104 patients) and 1.3 micrograms/ml (range 0.0-28.7 micrograms/ml in 13 patients), respectively. A statistically significant correlation was found between the median antibody concentration and response for multiple time points during the treatment and followup. The mean serum antibody concentration was also inversely correlated with measurements of tumor bulk and with the number of circulating B cells at baseline. CONCLUSIONS: We conclude that Rituximab is therapeutically effective against B-cell lymphoma. Pharmacokinetic data suggests that certain subsets of patients may possibly benefit from increased dosing and studies to address this are currently underway.

Antibodies, Monoclonal↗
PubMed1998

Progesterone receptor subtype B is differentially regulated in human endometrial stroma.

Two anti-progesterone receptor (PgR) antibodies, a new one specific to PgRB, the other to PgR subtypes A + B, have been used to examine the cellular location of PgR subtypes A and B in normal endometrium throughout the menstrual cycle and in early human decidua by standard immunohistochemical techniques. PgR(A+B) is the receptor detected by the antibody recognizing both isoforms of the receptor. PgRB is the receptor detected by the new antibody specific to the B isoform. Since it is not possible to raise antibody specific to PgR subtype A, all immunohistochemical analysis of the PgRA subtype is by subtractive inference. Thus we refer to PgRA as the subtype responsible for positive immunoreactivity when the PgRB subtype cannot be specifically detected. Endometrial biopsies were collected from 40 women with regular menses (n = 5 each stage of cycle: menstrual; early, mid and late proliferative; ovulatory; early, mid, and late secretory). Decidual tissue was obtained from 10 women undergoing first trimester surgical termination of pregnancy. As previously reported, the PgR(A+B) antibody stained glandular and stromal nuclei during the proliferative phase but only stromal nuclei during the secretory phase and early pregnancy. The new PgRB antibody also stained both cell types intensely during the proliferative phase, but failed to stain either stromal or glandular nuclei strongly during the secretory phase and early pregnancy. We concluded that, while both PgR subtypes were present in glands and stroma in the proliferative phase, and both subtypes were dramatically reduced in the glands during the secretory phase, PgRA remained as the predominant type in the stroma during the secretory phase and early pregnancy. The profound effects of progesterone on endometrium during the secretory phase and early pregnancy appear to be mediated primarily by PgRA in the stroma.

Adult↗
PubMed1998

Binding and lysing of blood clots using MRX-408.

RATIONALE AND OBJECTIVES: A thrombus-specific ultrasound contrast agent, MRX-408, has been developed recently. This agent consists of phospholipid-coated microbubbles with a ligand capable of targeting the GPIIb/IIIa receptor, thereby allowing the microbubbles to bind with thrombi rich in activated platelets. In vitro and in vivo animal experiments have been conducted to examine imaging enhancement and sonothrombolysis using this agent compared with a nontargeted agent. METHODS: For clot binding, blood-smeared slides were incubated with microbubbles and examined under a light microscope. Change in backscatter signals from the blood clots after binding was examined by both an ultrasound scanner and two single-element transducers arranged in a transmitter-receiver pair. For clot lysis, either 1-MHz or 20-KHz ultrasound was used to enhance the lysing effects of MRX-408 with or without urokinase. RESULTS: Evidence of binding was demonstrated under a microscope. In vitro experiments showed that the "acoustic signature", or properties, of blood clots changed after binding. Clots became more echogenic and nonlinear. In vivo fundamental ultrasound imaging confirmed that as a result of binding, blood clots were more visible, the area of detection was improved, and shadowing behind clots was more noticeable. Under 1-MHz ultrasound and 30 minutes of treatment, lysis efficiency reached 34% with MRX-408, whereas there was no visible clot lysis with saline. CONCLUSION: The results of these preliminary studies show that as a contrast agent, MRX-408 enhanced clots under ultrasound imaging and facilitated sonothrombolysis with or without thrombolytic drugs.

Animals↗
PubMed1998

Rituximab chimeric anti-CD20 monoclonal antibody therapy for relapsed indolent lymphoma: half of patients respond to a four-dose treatment program.

PURPOSE: The CD20 antigen is expressed on more than 90% of B-cell lymphomas. It is appealing for targeted therapy, because it does not shed or modulate. A chimeric monoclonal antibody more effectively mediates host effector functions and is itself less immunogenic than are murine antibodies. PATIENTS AND METHODS: This was a multiinstitutional trial of the chimeric anti-CD20 antibody, IDEC-C2B8. Patients with relapsed low grade or follicular lymphoma received an outpatient treatment course of IDEC-C2B8 375 mg/m2 intravenously weekly for four doses. RESULTS: From 31 centers, 166 patients were entered. Of this intent-to-treat group, 48% responded. With a median follow-up duration of 11.8 months, the projected median time to progression for responders is 13.0 months. Serum antibody levels were sustained longer after the fourth infusion than after the first, and were higher in responders and in patients with lower tumor burden. The majority of adverse events occurred during the first infusion and were grade 1 or 2; fever and chills were the most common events. Only 12% of patients had grade 3 and 3% grade 4 toxicities. A human antichimeric antibody was detected in only one patient. CONCLUSION: The response rate of 48% with IDEC-C2B8 is comparable to results with single-agent cytotoxic chemotherapy. Toxicity was mild. Attention needs to be paid to the rate of antibody infusion, with titration according to toxicity. Further investigation of this agent is warranted, including its use in conjunction with standard chemotherapy.

Adult↗