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Biomedical subjects

Z Huang

Publications and source records attributed to Z Huang.

At least 271 records · Page 15Linked to original sources
PubMed1998

Automatic matching of homologous histological sections.

The role of neuroanatomical atlases is undergoing a significant redefinition as digital atlases become available. These have the potential to serve as more than passive guides and to hold the role of directing segmentation and multimodal fusion of experimental data. Key elements needed to support these new tasks are registration algorithms. For images derived from histological procedures, the need is for techniques to map the two-dimensional (2-D) images of the sectional material into the reference atlas which may be a full three-dimensional (3-D) data set or one consisting of a series of 2-D images. A variety of 2-D-2-D registration methods are available to align experimental images with the atlas once the corresponding plane of section through the atlas has been identified. Methods to automate the identification of the homologous plane, however, have not been previously reported. In this paper we use the external section contour to drive the identification and registration procedure. For this purpose, we model the contours by B-splines because of their attractive properties the most important of which are: 1) smoothness and continuity; 2) local controllability which implies that local changes in shape are confined to the B-spline parameters local to that change; 3) shape invariance under affine transformation, which means that the affine transformed curve is still a B-spline whose control points are related to the object control points through the transformation. In this paper we present a fast algorithm for estimating the control points of the B-spline which is robust to nonuniform sampling, noise, and local deformations. Curve matching is achieved by using a similarity measure that depends directly on the parameters of the B-spline. Performance tests are reported using histological material from rat brains.

Animals↗
PubMed1998

Digital radiology using active matrix readout of amorphous selenium: detectors with high voltage protection.

A flat-panel x-ray imaging detector is being investigated for digital radiography and fluoroscopy. The detector uses a layer of amorphous selenium (a-Se) to convert x rays to a charge image, which is then electronically read out with a two-dimensional array of thin film transistors (TFTs). In order to sensitize the a-Se layer to x rays, a high voltage (of the order of several thousand volts) is applied to its top surface. The TFTs, which are at the bottom surface of the a-Se layer, are not subjected to any high voltage under normal radiological operational conditions since the pixel potential is < 10 V. However under a fault condition where these two events occur simultaneously: (1) suspended detector scan; and (2) an x-ray exposure more than ten times higher than normal, the voltage on the TFTs could rise to a damaging value. This paper describes a method for protecting the TFTs from high voltage damage under this fault condition. It employs a dual-gate TFT structure, one gate is for scanning control and the other is connected to the pixel electrode for high voltage protection. Before the pixel potential reaches a damaging value, the protection gate turns on the TFT automatically and drains excess charge away from the pixel thus providing a safe pixel saturation potential. In this paper, the characteristic curves of dual-gate TFTs are studied both theoretically and experimentally. The pixel x-ray response for imaging detectors with high voltage protection are predicted, and it is shown that with practical TFT designs the detector can provide a safe pixel saturation potential as well as satisfy the dynamic range required for diagnostic x-ray imaging applications.

Equipment Design↗
PubMed1998

Signals transmitted along retinal axons in Drosophila: Hedgehog signal reception and the cell circuitry of lamina cartridge assembly.

The arrival of retinal axons in the brain of Drosophila triggers the assembly of glial and neuronal precursors into a 'neurocrystalline' array of lamina synaptic 'cartridges'. Hedgehog, a secreted protein, is an inductive signal delivered by retinal axons for the initial steps of lamina differentiation. In the development of many tissues, Hedgehog acts in a signal relay cascade via the induction of secondary secreted factors. Here we show that lamina neuronal precursors respond directly to Hedgehog signal reception by entering S-phase, a step that is controlled by the Hedgehog-dependent transcriptional regulator Cubitus interruptus. The terminal differentiation of neuronal precursors and the migration and differentiation of glia appear to be controlled by other retinal axon-mediated signals. Thus retinal axons impose a program of developmental events on their postsynaptic field utilizing distinct signals for different precursor populations.

Animals↗
PubMed1998

Dipyridamole thallium-201 single-photon emission computed tomography for prediction of perioperative cardiac events in patients with arteriosclerosis obliterans undergoing vascular surgery.

The aim of the study was to determine whether or not dipyridamole thallium-201 single-photon emission computed tomography (201Tl-SPECT) has significant additive value for predicting perioperative cardiac events in patients with arteriosclerosis obliterans (ASO) undergoing vascular surgery. Routine preoperative 201Tl-SPECT was performed in 106 consecutive patients with ASO (age 68+/-8.9 years; 91 men and 15 women). The frequency of reversible defects in a clinical high-risk group (n=44) was significantly higher than in a low-risk group (n=62; 55% vs 24%, p<0.01). Perioperative cardiac events occurred in 9 patients, including 4 cardiac deaths, 1 non-fatal myocardial infarction, and 4 cases of unstable angina. Although clinical risk stratification was useful in predicting cardiac events (19% in the high-risk group vs 2% in the low-risk group, p<0.01), the positive predictive value was low. When considering a combination of 2 or more than 2 risk factors and a large reversible defect as a predictor, the positive predictive value and specificity increased from 19% to 47% and from 64% to 91%, respectively, whereas the sensitivity remained unchanged (89%). These results suggest that the addition of 201Tl-SPECT data to clinical risk-stratified patients with ASO allows better prediction of perioperative cardiac events.

Adult↗
PubMed1998

Redesigning nucleic acids.

A research program has applied the tools of synthetic organic chemistry to systematically modify the structure of DNA and RNA oligonucleotides to learn more about the chemical principles underlying their ability to store and transmit genetic information. Oligonucleotides (as opposed to nucleosides) have long been overlooked by synthetic organic chemists as targets for structural modification. Synthetic chemistry has now yielded oligonucleotides with 12 replicatable letters, modified backbones, and new insight into why Nature chose the oligonucleotide structures that she did.

Catalysis↗
PubMed1998

Coupling of calcium receptors to inositol phosphate and cyclic AMP generation in mammalian cells and Xenopus laevis oocytes and immunodetection of receptor protein by region-specific antipeptide antisera.

Ca2+ and other divalent cations modulate parathyroid hormone secretion by interacting with cell-surface Ca2+-sensing receptors (CaRs). We assessed the ability of these receptors to couple to Ca2+ mobilization, inositol phosphate (InsP) accumulation, and cyclic AMP production in different expression systems. In Xenopus laevis oocytes injected with bovine parathyroid CaR cRNA, the addition of extracellular cations to 1.5 mM Ca2+, 5.5 mM Mg2+, or 10 microM Gd3+ significantly increased 45Ca efflux (p < 0.01). InsP accumulation also increased dramatically when adding these cations to human embryonic kidney (HEK) 293 cells stably transfected with wild-type bovine parathyroid CaR cDNA. Raising the extracellular [Ca2+] ([Ca2+]o) from 0.1 to > 1.4 mM in oocytes and to > 1.0 mM in HEK 293 cells stimulated significant increments in 45Ca efflux and InsP accumulation, respectively (p < 0.05). In contrast, Ca2+ and Mg2+ increased InsPs to a lesser extent in COS 7 cells transiently transfected with CaR cDNA. In HEK 293 cells stably expressing CaR cDNA, there were significant reductions in cAMP content when adding high Ca2+, Mg2+, Gd3+, or the CaR modulator NPS R-467. Three region-specific anti-CaR peptide antisera immunoblotted bands of approximately 140 and 155 kDa in membranes from CaR-transfected HEK 293 cells and bovine parathyroid tissue. Immunocytochemistry demonstrated strong cell-surface staining in CaR-transfected HEK 293 cells and parathyroid tissue, which was absent when antisera were preabsorbed with CaR peptides. These results indicate that the activation of the recombinant CaR by extracellular Ca2+ can couple negatively to adenylate cyclase but positively to phospholipase C (PLC), the latter at physiological [Ca2+]o.

Amino Acid Sequence↗
PubMed1998

[The effects of hypertonic saline/mannitol resuscitation on the myocardiac contractility and blood pressure of rabbits with hemorrhagic shock].

Eighteen healthy adult male rabbits were hemorrhaged to shock and treated with hypertonic-hyperoncotic solutions in 3 groups (6 per group): hypertonic saline/dextran(HSD), hypertonic saline/mannitol(HSM) and hypertonic acetate/mannitol(HAM). The results showed that HSM. HAM and HSD could raise the left ventricular pressure(LVP), maximum change rate of LVP (+/- dp/dt max) and the arterial blood pressure of hemorrhagic shock rabbits quickly at small dose. The efficiency of HSM was better than that of HSD and HAM (P < 0.05), and the time of blood pressure rise was in accordance with that of LVP and +/- dp/dt max, which may partly explain the mechanism of shock resuscitation by hypertonic-hyperoncotic solution.

Animals↗
PubMed1998

[Protection of hypertonic saline/mannitol to thymic cell apoptosis induced by endotoxin (LPS) in mice].

To observe the effect of HSM (hypertonic saline/mannitol) on thymic cell apoptosis induced by endotoxin (LPS) in mice, twenty-four mice were divided into three groups (8 mice/each group): 1. Control group, each mouse was intraperitonealy injected with normal saline; 2. LPS group, each mouse was intraperitonealy injected with LPS; 3. LPS + HSM group, each mouse was intraperitonealy injected with HSM before and after injection of LPS. The results showed that the percentage of apoptosis of HSM + LPS group was lower than that of LPS group (P < 0.01); the ladder of nucleosomal DNA fragments by agarose gel eletrophoresis of HSM group was not typical as compared with that of LPS group. It is suggested that HSM might protect the apoptosis of mouse thymic cell induced by LPS and may improve the immune function.

Adjuvants, Immunologic↗
PubMed1998

[Data cleaning in the 1995-1996 national smoking prevalence survey].

The authors introduced the procedure of data cleaning in the 1995-1996 national smoking prevalence survey, and the objectives, principles, procedures, quality evaluation and points for attention of data cleaning were summarized. Data cleaning must be carried out from the smallest investigative unit. The logical relationship among variables must be fully considered for the revision of incorrect values. In dealing with miss values, their roles in the statistical analyses must be evaluated. Comparing the differences in some important variables before and after cleaning is a useful method for assessing whether the representativeness of the data has been changed during the cleaning process.

China↗
PubMed1998

[Immunoprotection in guinea pigs using DNA recombinant plasmid rpDJt and expressed protein P68 in L. interrogans serovar lai].

Immunoprotection against the infection by Leptospira interrogans serogroup Icterohemorrhagiae serovar lai strain 017 was demonstrated in guinea pigs vaccinated with DNA recombinant plasmid rpDJt and expressed protein P68 derived from genomic library of Leptospira strain 017. Thirty days after active immunization, each group received intraperitoneally (1/2 dose) and subcutaneously (1/2 dose) inoculum of L. interrogans serovar lai stain 017; cultures were adjusted to 5 x 10(8) cells/ml. All guinea pigs were observed for 10 days after challenge. Survival (%) of P68 group was 100(7/7); P23 group was 75(3/4); group rpDJt was 77(10/13); group lack recombinant (control) pT7-7 was 25 (3/12), and group with whole-cell inactivated vaccine was 93(13/14). Although the protective antigen in the leptospires has yet to be determined, it is evident that expressed protein P68 conferred a high degree of immunoprotection in guinea pigs.

Animals↗
PubMed1998

[Study on nuclear matrix protein in leukemia cells].

OBJECTIVE: To compare the composition of nuclear matrix proteins (NMP) between leukemia cells and normal bone marrow cells. METHODS: NMP was isolated by high-salt extration and identified by SDS-PAGE and western blotting. RESULTS: Increase in NMP was demonstrated in acute and chronic myelogenous leukemic cells as well as in the blast phase of chronic leukemia. On SDS-PAGE, NMPs with molecular weight different from what were seen in normal bone marrow cells were present in both acute and chronic myelogenous leukemias. CONCLUSION: Marked changes of NMP, not only in contents but also in compositions, exist in leukemic cells compared with normal bone marrow cells. NMP may serve as a target of chemotherapeutic drugs against leukemia.

Antigens, Nuclear↗
PubMed1998

[Gene expression in vivo mediated by adenoviral vector after direct gene transfer into anastomotic rat carotid arteries].

OBJECTIVE: To observe the efficiency and time course of gene expression in vivo mediated by adenoviral vector after direct gene transfer into anastomotic rat carotid arteries. METHODS: After being soaked in high concentration of glucose solution containing Adv5-CMV (control group) or Adv5-CMV/LacZ (treatment group) for 30 minutes, soluble stents were inserted into the lumina of cut rat carotid arteries and end-to-end anastomoses were performed. On the 2nd, 7th, 14th, 28th, 60th and 90th day after surgery, the anastomotic carotid arteries of the two groups were explanted. All samples were analyzed for the presence of beta-galactosidase activity and histochemical staining. RESULTS: beta-galactosidase activity was not detected in the carotid arteries of the control group. Microscopic examination of sections from vessels of the control group revealed no X-gal staining. The treatment group revealed bluestaining in all anastomotic arteries and in all layers of the arterial wall explanted including the intima, media, and adventitia on the 7th, 14th day postoperatively. CONCLUSIONS: Adenoviral vector could make foreign effectively transfer into rat carotid arteries in vivo. Mediated by adenoviral vector after direct gene transfer into anastomotic rat carotid arteries, the high level of gene expression only persisted about one month.

Adenoviruses, Human↗
PubMed1998

[Studies of tumor necrosis factor-alpha and red cell immunity state in multiple myeloma].

OBJECTIVE: To explore factors in the pathogenesis of multiple myeloma (MM). METHODS: The plasma level of tumor necrosis factor-alpha (TNF alpha) was measured by immunoassay in 21 MM patients, and red cell immunologic function was assayed in 16 patients. RESULTS: There was no difference in TNF alpha levels among patients with either fulminant MM or stable MM and normal controls. The rosette formation rate of red cell C3 bR and red cell immune complex was significantly lower in MM patients than in the controls. CONCLUSION: MM patients might have impaired monocyte-phagocyte system and red cell immune function.

Adult↗
PubMed1998

[Analysis of MDMA and its metabolites in urine by GC and GC/MS].

The purpose of this study is to investigate the metabolism of MDMA in the person and establish the methods for the determination of MDMA and its metabolites in urine. MDMA and its metabolite were isolated from urine by liquid-liquid extraction after acidic or enzymatic hydrolysis and were determined by GC/MS(EI, PCI) and GC/FID. The results showed that MDMA was metabolized to MDA and HMMA in man. MDA in the urine after MDMA administration was approximately 0.10-0.14 that of the parent drug. The sensitivity limits of methods were 2-50 ng/ml, and the recoveries were greater than 85%(CV < 10%). It is concluded that the methods were simple, quick and accurate for determining urine concentration of MDMA addicts. MDA/MDMA Ratio can be used to indicate whether the parent drug is taken alone or in combination with its active metabolite.

3,4-Methylenedioxyamphetamine↗
PubMed1998

[The role of pro-UK gene in protecting vein graft from thrombosis].

OBJECTIVE: To study the role of Pro-UK gene in protecting vein graft from thrombosis. METHODS: 42 Wister rats underwent implantation of reversed autologous jugular vein interposition grafts in the common carotid artery. Jugular veins were exercised and distended with solution containing either Adv5-CMV(control group) or Adv5-CMV/Pro-UK(treatment group) for 30 minutes, then the jugular veins were reversed and interposed into the divided carotid arteries. Proximal and distal anastomoses were performed in an end to end fashion with interrupted 11-0 polypropylene sutures. 14 days after surgery, the vein graft of two groups were explanted to examine the presence of Pro-UK gene expression. The amount of 51 Cr-labeled platelet of the two groups was counted 24 hours postoperatively. Segment of grafts of both group was explanted 14 days after surgery for histologic analysis. RESULTS: Pro-UK activity was not detected in the vein graft of the control group. In the treatment group, the amount of Pro-UK gene express was 308 IU/g tissue. The amount of 51Cr-labeled platelet of the two groups was (123.7 +/- 19.4) x 10(6)/gdrywt. (34.4 +/- 5.3) x 10(6)/gdrywt. The amount of the control group was prominent over the treatment group(P < 0.01). On the 14th day after surgery, the thrombosis rate and occlusion rate of the vein graft in the control group were 30%, 10% respectively. In the treatment group, all vein grafts were patent and free of thrombosis. CONCLUSIONS: Mediated by adenoviral vector after direct gene transfer into vein graft, Pro-UK gene expression could protect graft from thrombosis. Therefore, this method could effectively enhance venous graft patency.

Animals↗