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Biomedical subjects

Dong Zhang

Publications and source records attributed to Dong Zhang.

At least 55 records · Page 3Linked to original sources
PubMed2005

[Application of intraoperative real-time ultrasound in the surgical treatment of cerebral arteriovenous malformation].

OBJECTIVE: To investigate the value of intraoperative real-time ultrasound during surgery of cerebral arteriovenous malformations (AVMs). METHODS: Thirteen patients with cerebral AVMs, 12 supratentorial and 1 infratentorial, underwent microsurgical treatment. Intraoperative ultrasound (IOUS) with multimodality was performed before the starting of resection in order to: (1) localize and delineate the AVM, (2) differentiate the embolized and perfused parts of AVM, and (3) identify the feeding arteries and draining veins. After removal of the lesion, sonographic examination was repeated to detect the residual AVM tissue and the findings were compared with the intra- and/or post-operative angiographic finding. RESULTS: Total resection was achieved in all 13 patients with AVM under real-time ultrasonographic navigation. The niduses of AVM were localized and defined precisely by IOUS due to their dichromatic flow pattern. The embolized parts of AVM exhibited hyperechogenicity without blood signals. The feeding and draining vessels were distinguished from normal ones morphologically and hemodynamically. Complete removal of the AVM determined sonographically was then confirmed by angiography. CONCLUSIONS: Intraoperative real-time ultrasound allows accurate localization and navigation of the cerebral AVMs, provides valuable information during surgery, and helps determine the degree of removal of the cerebral AVM.

Adolescent↗
PubMed2005

Granzyme B binds to target cells mostly by charge and must be added at the same time as perforin to trigger apoptosis.

Perforin (PFN) delivery of granzymes (Gzm) into the target cell at the immunological synapse is the major pathway for inducing apoptosis of virus-infected cells and tumors. A validated model for how PFN delivers Gzm into the cytosol is still lacking. PFN was originally thought to work by forming pores in the target cell plasma membrane that allow Gzm entry. This model was questioned when it was shown that GzmB is endocytosed without PFN. Moreover, apoptosis could be triggered by adding PFN to washed cells that have previously endocytosed GzmB. In this study, we show that GzmB binds to the plasma membrane mostly via nonspecific charge interactions. Washing in saline does not remove bound Gzm. However, if externally bound GzmB is completely removed, subsequent addition of PFN does not release previously endocytosed GzmB and does not trigger apoptosis. Therefore, PFN must be coendocytosed with GzmB to deliver it into the cytosol.

Animals↗
PubMed2005

Ruthenium(III) chloride catalyzed oxidation of pyrene and 2,7-disubstitued pyrenes: an efficient, one-step synthesis of pyrene-4,5-diones and pyrene-4,5,9,10-tetraones.

Pyrene and 2,7-disubstituted pyrenes have been oxidized with ruthenium(III) chloride (RuCl3) and sodium periodate (NaIO4) under very mild conditions to 4,5-diones or 4,5,9,10-tetraones. Thus, the oxidation has been controlled by varying the amount of oxidant and reaction temperature to proceed exclusively at the pyrene 4- and 5-positions or at the 4-, 5-, 9-, and 10-positions.

Journal Article↗
PubMed2005

Improvement of tissue harmonic imaging using the pulse-inversion technique.

Harmonic imaging has brought about significant improvements in image quality by taking advantage of the second harmonic component, but it still has one shortcoming, namely, a low signal-to-noise ratio. In this paper, a pulse-inversion technique is used in second harmonic imaging for biologic tissues to increase the signal-to-noise ratio. Enhancement of the second harmonic component is theoretically analyzed based on the theory of the finite amplitude sound wave and confirmed by the measurement. Second harmonic imaging for biologic tissues is constructed with the pulse-inversion technique and compared with the traditional fundamental frequency and also with second harmonic imaging before the use of this technique. Results demonstrate that this technique yields a dramatically cleaner and sharper contrast between the different structures of biologic tissues in ultrasonic images.

Acoustics↗
PubMed2005

Effectiveness of adjuvant chemotherapy for node-positive operable breast cancer in older women.

BACKGROUND: Randomized clinical trials have shown the efficacy of adjuvant chemotherapy in treating node-positive operable breast cancer in women aged < or = 69 years, but the benefit of chemotherapy in women aged > or = 70 is questionable. This study was to examine if adjuvant chemotherapy is effective for these women with breast cancer. METHODS: We studied a cohort of 5464 women diagnosed with node-positive operable breast cancer at age > or = 65 in 1992 through 1996 with last follow-up of December 31, 1999 in five states and six metropolitan areas. Hazard ratio (HR) for all-cause mortality was used for survival analysis with adjustment for patient and tumor characteristics; propensity analysis was used to control for observed factors; and sensitivity analysis was used to estimate potential effects of unmeasured confounders. RESULTS: After adjusting for propensity to receive chemotherapy, the chemotherapy-treated and untreated groups were not statistically significantly different for covariates except for age and hormone receptor status. Mortality was significantly reduced in women aged 65-69 who received adjuvant chemotherapy compared to those who did not, after adjusting for patient and tumor characteristics (HR = 0.70, 95% confidence interval [CI], 0.57-0.88) or after adjusting for propensity scores (HR = 0.76, 95% CI, 0.62-0.94). HR did not significantly differ between the treated and untreated women aged > or = 70 (HR = 0.96, 95% CI = 0.83-1.09, and HR = 0.99, 95% CI, 0.87-1.14). These results were relatively insensitive to changes in unmeasured confounders. CONCLUSIONS: Adjuvant chemotherapy is associated with improved survival in women with node-positive operable breast cancer aged 65-69 living in the community, but not in women aged > or = 70. These findings are consistent with those found in randomized controlled trials.

Aged↗
PubMed2005

Automatic analysis of multimodal group actions in meetings.

This paper investigates the recognition of group actions in meetings. A framework is employed in which group actions result from the interactions of the individual participants. The group actions are modeled using different HMM-based approaches, where the observations are provided by a set of audiovisual features monitoring the actions of individuals. Experiments demonstrate the importance of taking interactions into account in modeling the group actions. It is also shown that the visual modality contains useful information, even for predominantly audio-based events, motivating a multimodal approach to meeting analysis.

Algorithms↗
PubMed2005

[Qualitative and quantitative methods of betulonic acid in fruits of Liquidambar formosana].

OBJECTIVE: To develop the identification and assay methods for betulonic acid in fruits of Liquidambar formosana. METHOD: TLC method was used for identification with silica gel G plate and petroleum ether(60-90 degrees C)-acetone (17:3) as a developing solvent. Betulonic acid in ethanol extract was separated on the ODS column with methanol-water-glacial acetic acid (87:13:0.1) as mobile phase. Flow-rate was 1.0 mL x min(-1), and column temperature 35 degrees C. ELSD drift-tube temperature was 82 degrees C, and gas flow 1.25 L x min(-1). RESULT: The qualitative method is repeatable. Betulonic acid in ethanol extracts is well separated, relationship of logarithms of injection amount and peak area is linear (r = 0.9997) within the range of 0.65-3.25 microg. The average recovery is 98.0% and RSD of repeatability is 2.5%. 11 crude drugs purchased from different areas in the country were identified and quantified with the methods. CONCLUSION: The methods and data could be used for quality control of fruits of L. formosana.

Chromatography, Thin Layer↗
PubMed2005

[Study of the expression of integrin alphaV beta3 in mandibular distraction osteogenesis].

OBJECTIVE: To investigate the expression and distribution pattern of Integrin alphaV beta3 (ItgalphaV beta3) in course of distraction 44 adults New Zealand white osteogenesis and to quest for the function of ItgalphaV beta3 in distraction osteogenesis (DO). METHODS: rabbits were selected and divided randomly into 3 groups: DO, bone fracture and normal group. There were 20, 20 and 4 rabbits in each group separately. Animal models were established and animals were killed at different time points. Sections were stained by IHC method. Distribution and expression pattern of ItgalphaV beta3 were observed by semi-quantitative technique, and the results were managed with statistic methods. RESULTS: The expression of ItgalphaV beta3 was found both in the DO and bone fracture groups. The positive staining was seen mainly in vascular endothelial cells on cytomembrane and in cytoplasm. The staining intensity of group of DO was higher than that of the bone fracture group. CONCLUSION: ItgalphaV beta3 plays an important role in promoting the process of DO.

Animals↗
PubMed2004

C1 inhibitor prevents Gram-negative bacterial lipopolysaccharide-induced vascular permeability.

Gram-negative bacterial endotoxemia may lead to the pathological increase of vascular permeability with systemic vascular collapse, a vascular leak syndrome, multiple organ failure (MOF), and/or shock. Previous studies demonstrated that C1 inhibitor (C1INH) protects mice from lipopolysaccharide (LPS)-induced lethal septic shock via a direct interaction with LPS. Here, we report that C1INH blocked the LPS-induced increase in transendothelial flux through an endothelial monolayer. In addition, LPS-mediated detachment of cultured endothelial cells was prevented with C1INH. C1INH also inhibited LPS-induced endothelial cell apoptosis as demonstrated by suppression of DNA fragmentation and annexin V expression. As illustrated by laser scanning confocal microscopy, C1INH completely blocked the binding of fluorescein isothiocyanate (FITC)-LPS to human umbilical vein endothelial cells (HUVECs). C1INH protected from localized LPS-induced increased plasma leakage in C57BL/6J mice and in C1INH-deficient mice. Local vascular permeability in response to LPS was increased to a greater extent in C1INH-deficient mice compared with wild-type littermate controls and was reversed by treatment with C1INH. Systemic administration of LPS to mice resulted in increased vascular permeability, which was reduced by C1INH. Therefore, these studies demonstrate that C1INH, in addition to its role in suppression of LPS-mediated macrophage activation, may play an important role in the prevention of LPS-mediated increased vascular permeability, endothelial cell injury, and multiple organ failure.

Animals↗
PubMed2004

Reduced expression of MAD2, BCL2, and MAP kinase activity in pig oocytes after in vitro aging are associated with defects in sister chromatid segregation during meiosis II and embryo fragmentation after activation.

This study was conducted to examine expression of centromere protein B (CENPB), spindle checkpoint protein MAD2 (mitotic arrest deficient protein), and antiapoptotic protein BCL2; activities of MAPK (mitogen-activated protein kinase) and mitochondria distribution in pig oocytes during aging, and their relationship with sister chromatid separation during meiosis II and embryo fragmentation and apoptosis after activation. After immature oocytes were cultured for 40-72 h, CENPB, MAD2, tubulin, BCL2, and MAPK in the oocytes were examined by immunoblotting. Spindles, chromosomes, kinetochores, and mitochondria were examined by immunofluorescence staining and apoptosis was examined by TUNEL assay. It was found that tubulin and CENPB was not changed during 40-72 h of culture. However, the expression of MAD2 and BCL2 and the activity of MAPK were gradually reduced during oocyte aging. The percentages of oocytes with normal spindle, chromosomes, and kinetochores were also reduced as oocyte aged from 9.5% at 40 h to 17.3%, 34.6%, and 42.9% at 48, 60, and 72 h, respectively. Aggregated mitochondria were found in the aged oocytes as compared with the uniform distribution in young oocytes. After activation, the proportions of oocytes with abnormal anaphase II were significantly increased in aged oocytes. More (P<0.001) oocytes cultured for 60-72 h fragmented and showed apoptosis after activation as compared with the oocytes cultured for 40-48 h. This study indicates that aging reduces expression in spindle checkpoint protein and antiapoptosis protein and MAPK activity in pig oocytes. These events in turn cause abnormal sister chromatid segregation during meiosis II, embryo fragmentation, and apoptosis.

Anaphase↗
PubMed2004

Localization of mitotic arrest deficient 1 (MAD1) in mouse oocytes during the first meiosis and its functions as a spindle checkpoint protein.

The present study was designed to investigate the localization of mitotic arrest deficient 1 (MAD1) in mouse oocytes during meiotic maturation and its relationship with kinetochores, chromosomes, and microtubules. Oocytes at various stages during the first meiosis were fixed and immunostained for MAD1, kinetochores, microtubules, and chromosomes. The stained oocytes were examined by confocal microscopy. Some oocytes were treated with nocodazole or Taxol before examination. The anti-MAD1 antibody was injected into the oocytes at the germinal vesicle (GV) stage for examination of chromosome alignment and spindle formation. It was found that MAD1 was present in the oocytes from the GV to prometaphase I stages around the nuclei. When the oocytes reached the metaphase I (M-I) to metaphase II (M-II) stages, MAD1 was mainly localized at the spindle poles. However, MAD1 relocated to the vicinity of the chromosomes when spindles were disassembled by nocodazole or cooling, and the relocated MAD1 moved back to the spindle poles during spindle recovery. Taxol treatment did not affect the MAD1 localization. Although anti-MAD1 antibody injection did not affect nuclear maturation, significantly higher proportions of injected oocytes had misaligned chromosomes when the oocytes reached the M-I to M-II stages. The results of the present study indicate that MAD1 is present in mouse oocytes at all stages during the first meiosis and that it participates in spindle checkpoint during meiosis. However, MAD1 could not check misaligned chromosomes during spindle recovery after the spindles were destroyed by drug or cooling, which caused some chromosomes to scatter in the oocytes.

Animals↗
PubMed2004

Photosensitized oxidative deprotection of oximes to their corresponding carbonyl compounds by platinum(II) terpyridyl acetylide complex.

Platinum(II) terpyridyl acetylide complex (1) photosensitizes the oxidation of aldoximes 2-4, aliphatic acyclic and cyclic ketoximes 5-7, and aromatic ketoximes 8-10 into their corresponding carbonyl compounds with good to excellent yields in acetonitrile solution. This deprotection of oximes proceeds via singlet oxygen ((1)O(2)) mechanism. The photosensitizer can be easily separated from the product and unreacted starting material by extraction with ethyl acetate and reused for photooxidation without loss of (1)O(2)-generation capacity.

Journal Article↗
PubMed2004

[Application of the neuro-endoscope to the intracranial aneurismal surgery].

OBJECTIVE: To study the role of neuro-endoscope in the intracranial aneurismal surgery, analyzing its benefits, and disadvantages. METHODS: Endoscopy was used as an adjunct in the microsurgical treatment of clipping aneurysms on 88 patients with 89 aneurysms, of which 82 aneurysms in 81 patients were located in the anterior circulation and 7 were located in the posterior circulation. Keyhole approach was performed on all patients, and micro-Doppler ultrasound technique was used before and after clipping. In 84 aneurysms, endoscope-assisted microneurosurgery (EAM) was used in addition to microsurgical dissection and clipping so as to observe the neck anatomic features and perforators and to verify the optimal clipping position. Endoscope-controlled microneurosurgery was used for 5 aneurysms to observe the anatomy around aneurysm, such as the posterior communicating artery and the opposite anterior communicating artery behind the internal carotid artery. RESULTS: Postoperative angiography performed on 86 patients showed satisfactory aneurysm clipping. Operative mortality was 0. There were 7 cases of postoperative complications, with an incidence rate of 7.95%, and none case was directly related to endoscopy. CONCLUSION: Improving observation of regional anatomy because of its ability in magnification, illumination, and looking around dead angle, neuro-endoscopy is very useful for complex aneurysms.

Adult↗
PubMed2004

Intra-oocyte localization of MAD2 and its relationship with kinetochores, microtubules, and chromosomes in rat oocytes during meiosis.

The present study was designed to investigate subcellular localization of MAD2 in rat oocytes during meiotic maturation and its relationship with kinetochores, chromosomes, and microtubules. Oocytes at germinal vesicle (GV), prometaphase I (ProM-I), metaphase I (M-I), anaphase I (A-I), telophase I (T-I), and metaphase II (M-II) were fixed and immunostained for MAD2, kinetochores, microtubules and chromosomes. The stained oocytes were examined by confocal microscopy. Some oocytes from GV to M-II stages were treated by a microtubule disassembly drug, nocodazole, or treated by a microtubule stabilizer, Taxol, before examination. Anti-MAD2 antibody was also injected into the oocytes at GV stage and the injected oocytes were cultured for 6 h for examination of chromosome alignment and spindle formation. It was found that MAD2 was at the kinetochores in the oocytes at GV and ProM-I stages. Once the oocytes reached M-I stage in which an intact spindle was formed and all chromosomes were aligned at the equator of the spindle, MAD2 disappeared. However, when oocytes from GV to M-II stages were treated by nocodazole, spindles were destroyed and MAD2 was observed in all treated oocytes. When nocodazole-treated oocytes at M-I and M-II stages were washed and cultured for spindle recovery, it was found that, once the relationship between microtubules and chromosomes was established, MAD2 disappeared in the oocytes even though some chromosomes were not aligned at the equator of the spindle. On the other hand, when oocytes were treated with Taxol, MAD2 localization was not changed and was the same as that in the control. However, immunoblotting of MAD2 indicated that MAD2 was present in the oocytes at all stages; nocodazole and Taxol treatment did not influence the quantity of MAD2 in the cytoplasm. Significantly higher proportions of anti-MAD2 antibody-injected oocytes proceeded to premature A-I stage and more oocytes had misaligned chromosomes in the spindles. The present study indicates that MAD2 is a spindle checkpoint protein in rat oocytes during meiosis. When the spindle was destroyed by nocodazole, MAD2 was reactivated in the oocytes to overlook the attachment between chromosomes and microtubules. However, in this case, MAD2 could not check unaligned chromosomes in the recovered spindles, suggesting that a normal chromosome alignment is maintained only in the oocytes without any microtubule damages during maturation.

Animals↗
PubMed2004

Study of acoustic nonlinearity parameter imaging methods in reflection mode for biological tissues.

Three novel methods for acoustic nonlinearity parameter B/A imaging in reflection mode are developed in this paper. They are: (1) the acoustic nonlinearity parameter B/A tomography by detecting reflective second harmonic wave, (2) the B/A tomography in reflection mode via the measurement of the difference frequency wave generated by a parametric array, and (3) the C-scan imaging of B/A via the measurement of the echo second-harmonic signal. A theoretical analysis and the experimental imaging of normal and pathological biological tissues by using these methods are also present and discussed. Results show that using the acoustic nonlinearity parameter imaging we can more easily distinguish the diseased tissue from the normal one than using the linear acoustic parameters.

Adipose Tissue↗