Biomedical subjects

X Deng

Publications and source records attributed to X Deng.

At least 19 recordsLinked to original sources

PubMed2000

Influence of process parameters on the protein stability encapsulated in poly-DL-lactide-poly(ethylene glycol) microspheres.

Glucose oxidase (GOD) has been encapsulated as a model protein within poly-DL-lactide-poly(ethylene glycol) (PELA) microspheres to evaluate the activity retention during microencapsulation process. This paper was aimed to investigate the effect of process parameters, such as the preparation method, the used matrix polymer with different compositions, the solvent system and the addition of stabilizer on the structural integrity and activity retention of encapsulated protein. The stability of the protein released during in vitro assay was also assessed. The obtained results showed that the solvent extraction/evaporation method based on the formation of double emulsion w(1)/o/w(2) benefited the activity retention compared with the phase separation method based on the formation of w/o(1)/o(2). And in the emulsion-evaporation system most of the protein activity was lost during the first emulsification procedure to form primary emulsion w(1)/o (ca. 28%) and the second emulsification procedure to form the double emulsion w(1)/o/w(2) (ca. 20%), in contrast to other processes occurring during microspheres preparation. The matrix polymer and the solvent system in the oil phase had an impressive impact on the activity retention, while the addition of gelatin in the internal aqueous phase resulted in no major reduction of activity loss. GOD release from PELA microspheres exhibited a triphasic profile, that is, the initial burst release during the first day, the gradual release over about 1 month, and then the second burst release. The encapsulation of GOD in PELA microspheres was effective in reducing its specific activity loss. Sixty-seven per cent of the initial specific activity retention was detected for the released GOD from microspheres formulation during 1 week of incubation, but nearly all the activity was lost for GOD in solution incubated under the same condition. SDS-PAGE results showed that, although the activity loss was detected, no rough changes of molecular weight of GOD was observed during encapsulation procedure and the initial days of incubation into the in vitro release medium.

Absorbable Implants↗

PubMed2000

Mirk protein kinase is a mitogen-activated protein kinase substrate that mediates survival of colon cancer cells.

We have cloned a novel gene mirk (minibrain-related kinase) encoding a protein kinase that enables colon carcinoma cells to survive under certain stress conditions. Mirk is a mitogen-activated protein kinase substrate but is down-regulated by activated extracellular signal-regulated kinases (erks) in vivo. Mirk contains a PEST region characteristic of rapidly turned over proteins and is broken down to a Mr 57,000 form only in the nucleus. In each of three colon carcinoma cell lines, mirk levels were increased 20-fold when erk activation was blocked by the MEK inhibitor PD98059 in serum-free medium. Addition of IGF-I to activate erks blocked this increase. Mirk was stably overexpressed in two colon carcinoma cell lines to attain levels seen in colon cancers. Each of five mirk transfectants proliferated when switched to serum-free medium and regained rapid growth when serum was restored, whereas five vector control transfectants and three kinase-dead mutant mirk transfectants did not. mirk mRNA levels were elevated in several types of carcinomas, and mirk protein was detected in each of seven colon carcinoma cell lines. mirk was expressed at a higher protein level in Western blots from three of eight colon cancers compared with paired normal colon tissue, suggesting that mirk plays a role in the evolution of a subset of colon cancers. mirk is not mutated in colon carcinomas. Mirk may mediate tumor cell survival in mitogen-poor environments or early in colon cancer development before many autocrine growth factors have been induced.

Amino Acid Sequence↗

PubMed2000

Survival function of ERK1/2 as IL-3-activated, staurosporine-resistant Bcl2 kinases.

Bcl2 phosphorylation at Ser-70 may be required for the full and potent suppression of apoptosis in IL-3-dependent myeloid cells and can result from agonist activation of mitochondrial protein kinase C (PKC). Paradoxically, expression of exogenous Bcl2 can protect parental cells from apoptosis induced by the potent PKC inhibitor, staurosporine (stauro). High concentrations of stauro of up to 1 microM only partially inhibit IL-3-stimulated Bcl2 phosphorylation but completely block PKC-mediated Bcl2 phosphorylation in vitro. These data indicate a role for a stauro-resistant Bcl2 kinase (SRK). We show that aurintricarboxylic acid (ATA), a nonpeptide activator of cellular MEK/mitogen-activated protein kinase (MAPK) kinase, can induce Ser-70 phosphorylation of Bcl2 and support survival of cells expressing wild-type but not the phosphorylation-incompetent S70A mutant Bcl2. A role for a MEK/MAPK as a responsible SRK was implicated because the highly specific MEK/MAPK inhibitor, PD98059, also can only partially inhibit IL-3-induced Bcl2 phosphorylation, whereas the combination of PD98059 and stauro completely blocks phosphorylation and synergistically enhances apoptosis. p44MAPK/extracellular signal-regulated kinase 1 (ERK1) and p42 MAPK/ERK2 are activated by IL-3, colocalize with mitochondrial Bcl2, and can directly phosphorylate Bcl2 on Ser-70 in a stauro-resistant manner both in vitro and in vivo. These findings suggest a role for the ERK1/2 kinases as SRKs. Thus, the SRKs can serve to functionally link the IL-3-stimulated proliferative and survival signaling pathways and, in a novel capacity, may explain how Bcl2 can suppress stauro-induced apoptosis. In addition, although the mechanism of regulation of Bcl2 by phosphorylation is not yet clear, our results indicate that phosphorylation may functionally stabilize the Bcl2-Bax heterodimerization.

Animals↗

PubMed2000

Mechanism and rate of degradation of polyhydroxyoctanoate films in aqueous media: A long-term in vitro study.

The present study investigated the in vitro mechanism and degradation rate of polyhydroxyoctanoate (PHO). Solution-cast PHO films were incubated in either water or isoosmotic phosphate-buffered saline (PBS) for periods ranging from 1 to 24 months. Physical characterization included weight loss, water absorption, pH change, tensile strength, and scanning electron microscopy (SEM) studies. Analytical investigations including electron spectroscopy for chemical analysis, Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), wide-angle X-ray diffraction, and size exclusion chromatography were also performed to assess chemical and morphological changes to the structure of the PHO. The results show that the PHO-cast films incubated in either water or isoosmotic PBS underwent a simple hydrolytic degradation process characterized by water absorption, gradual molecular weight decrease, and negligible mass loss after 24 months of incubation. DSC results suggest that degradation occurred in the amorphous zone, followed by an attack in the crystalline domain. An increase in the vibration stretching of OH after 24 months of incubation, as revealed by FTIR, may indicate that the degradation process began internally, moving outwardly toward the surface of the PHO films. This process was more rapid in the films incubated in PBS than in those incubated in water. However, no significant changes in the morphology of the films were detected by SEM. This study demonstrated that the in vitro degradation of PHO in water or in PBS is a very slow hydrolytic process, exceeding 2 years. Our findings also suggest that the internal degradation mechanism is faster in PBS because of the ionic strength of the medium and that this internal process surface moves gradually toward the surface.

Biocompatible Materials↗

PubMed2000

Alternative blood conduits: assessment of whether the porosity of synthetic prostheses is the key to long-term biofunctionality.

The paper examines the effects of water permeability on solid particle (platelet) adhesion and lipid transport through the wall of a blood conduit. Also tested is the capacity of external supports to reduce lipid infiltration into venous grafts. The results indicate that water permeability not only facilitates particle adhesion, but also affects the spatial distribution of the adhesion. The presence of filtration flow leads to a concentration polarisation of atherogenic lipids at the blood/wall interface, with increased lipid concentration from the bulk value towards the interface, thus enhancing the drive potential for lipid infiltration into the vessel wall. An external support to a venous graft guards against excessive distention and significantly reduces lipid infiltration into the venous wall. These results strongly suggest that too high a water permeability or porosity can lead to the late failure of arterial grafting by affecting blood cell interaction with the graft and lipid infiltration into the wall. Therefore the pore structure of an arterial prosthesis is crucial to its long-term biofunctionality. Ideally, a synthetic prosthesis should display pores of adequate size and a structural network that promotes tissue ingrowth, while maintaining water porosity at a physiological level.

Blood Platelets↗

PubMed2000

Phagocytic and intestinal endothelial and epithelial barrier function during the early stage of small intestinal ischemia and reperfusion injury.

The effects of intestinal ischemia and reperfusion (I/R) on small intestinal mucosal endothelial and epithelial barrier integrity and phagocytic function were assessed in rats subjected to 20- or 40-min mesenteric ischemia and a 3-h reperfusion. The results showed that human serum albumin (125I-HSA) flux through the endothelial layer to the interstitial space increased as did 125I-HSA clearance from blood to the gut lumen and 131I-HSA flux from the gut lumen to the interstitial space in rats with I/R. E. coli adhering to microvilli, invading and passing into the microvessels, were noted on the small intestinal mucosa in animals subjected to 40-min ischemia and a 3-h reperfusion. Phagocytic function increased, especially in the small intestinal wall, lungs, liver, and spleen in the groups with I/R, correlating with the length of ischemia. The results imply that both endothelial and epithelial barrier integrity is impaired in the early phase after I/R and that the epithelial barrier more effectively restricts macromolecular leakage compared with the endothelial barrier. I/R impairs the intestinal barrier not only by causing tissue hypoxia but also by activating the phagocytic system and aggravating barrier damage, which finally may result in bacterial translocation and remote organ dysfunction.

Animals↗

PubMed2000

Beneficial effects of lexipafant, a PAF antagonist on gut barrier dysfunction caused by intestinal ischemia and reperfusion in rats.

BACKGROUND: Platelet-activating factor (PAF) may play a pivotal role in the pathogenesis of intestinal ischemic injury. METHODS: The potential role of PAF in intestinal ischemia and reperfusion (I/R) and the development of gut endothelial and epithelial barrier dysfunction and distant organ injury were investigated by pretreatment with a PAF antagonist, lexipafant. Bidirectional permeability of the intestinal barrier, enteric bacterial translocation, protease-antiprotease balance and mucosal histology, and also changes in pulmonary and liver endothelial barrier permeability were measured following intestinal ischemia for 40 min with 6 h of reperfusion in rats. RESULTS: Intestinal mucosal endothelial and epithelial permeabilities significantly increased in animals with I/R. Lexipafant prevented the increase in albumin leakage from blood to the mucosal interstitium and the intestinal lumen during reperfusion, and the mucosal albumin leakage from the gut lumen to blood during I/R. Bacterial translocation was frequently noted in animals with I/R, while only a few positive cultures were obtained in animals with I/R administered lexipafant. Less leakage of fluorescein isothiocyanate dextran 70,000 into the interstitial space and gut lumen in I/R animals with lexipafant pretreatment was found under fluorescein microscopy. Lexipafant also partly prevented C1 inhibitor, prekallikrein, and factor X consumption in I/R animals and partly prevented changes in pulmonary and liver albumin leakage. CONCLUSIONS: PAF seems to play an important role in I/R-associated intestinal dysfunction and the development of distant organ dysfunction, probably by triggering endothelial and epithelial barrier dysfunction. Furthermore, PAF seems to be partly involved in activation of the protease-antiprotease system. The use of PAF antagonists may provide a mode of treatment against I/R-associated organ dysfunction.

Animals↗

PubMed2000

Body distribution of poly-DL-lactide-poly(ethylene glycol) microspheres with entrapped leptospira interrogans antigens following intravenous and oral administration to guinea-pigs.

Poly-DL-lactide-poly(ethylene glycol) (PELA) microspheres with entrapped antigens were administered intravenously and orally into guinea-pigs to quantitatively determine the in-vivo distribution and release profiles. PELA microspheres containing 125I-labelled outer-membrane protein Leptospira interrogans antigens (125I-OMP) were prepared by double-emulsion solvent extraction procedure, and characterized with respect to size, morphology and in-vitro release profiles. The fractured sections of liver and spleen were inspected by scanning electron microscopy, which indicated that microspheres had successfully been entrapped within the above tissues after intravenous injection and oral administration. At predetermined intervals, the blood and such tissues as the liver, spleen, kidney, thyroid, small intestine and mesentery were collected, and the radioactivity was measured by gamma scintillation counting. Following intravenous administration, 56.7% of administered microspheres were accumulated in immunization-related tissues, and 40.1% of microspheres were located in the liver and spleen. However, there was limited uptake efficiency (8.33%) following oral administration, and 49.5% of the absorbed microspheres were located in the intestinal mucosa. Compared with in-vitro release, the in-vivo release profiles of 125I-OMP from PELA microspheres, determined from the decreasing radioactivity in the above tissues, were much faster and the burst effect was higher. Antigen-loaded PELA microspheres were efficiently entrapped within immunization-related tissues after intravenous administration, but orally administered PELA microspheres showed limited uptake efficiency. Further investigation is needed to improve intestinal absorption.

Administration, Oral↗

PubMed2000

Fast algorithm for chirp transforms with zooming-in ability and its applications.

A general fast numerical algorithm for chirp transforms is developed by using two fast Fourier transforms and employing an analytical kernel. This new algorithm unifies the calculations of arbitrary real-order fractional Fourier transforms and Fresnel diffraction. Its computational complexity is better than a fast convolution method using Fourier transforms. Furthermore, one can freely choose the sampling resolutions in both x and u space and zoom in on any portion of the data of interest. Computational results are compared with analytical ones. The errors are essentially limited by the accuracy of the fast Fourier transforms and are higher than the order 10(-12) for most cases. As an example of its application to scalar diffraction, this algorithm can be used to calculate near-field patterns directly behind the aperture, 0 < or = z < d2/lambda. It compensates another algorithm for Fresnel diffraction that is limited to z > d2/lambdaN [J. Opt. Soc. Am. A 15, 2111 (1998)]. Experimental results from waveguide-output microcoupler diffraction are in good agreement with the calculations.

Algorithms↗

PubMed2000

Comparison of two PCR techniques used in amplification of microdissected plant chromosomes from rice and wheat.

Linker adaptor-mediated PCR (LAM-PCR) and degenerate oligonucleotide primed PCR (DOP-PCR) are major ways to generate chromosome-specific libraries. In this study, these two PCR techniques were used to amplify the microdissected mitotic and meiotic chromosomes from rice and wheat. The results of amplifications were compared, and the advantages and limitations between the two techniques are presented.

Blotting, Southern↗

PubMed2000

Correlation between bone mineral density and sexual hormones in healthy Chinese women.

Osteoporosis is a common disease in women, but not in men. It is usually induced by the deficiency of estrogen after menopause. The lumbar spine is most often affected. We examined 74 healthy Chinese women in whom we measured serum estradiol (E2), estriol (E3), and total testosterone (TTT) by radioimmunoassay (RIA). The bone mineral density (BMD) of the total lumbar spine in the anterior (TLS-A) and lateral (TLS-L) position, the region of interest (ROI) of lateral spine (M-IALS), the forearm, and the total hip (TH) were scanned by a dual-energy X-ray absorptiometer. We found that (1) E2 and all BMD determinations declined significantly after menopause (p < 0.05 for all), except the BMD of TH; (2) the BMD of TLS-L, TH, and forearm correlated significantly with E2 (r = 0.2986, p < 0.05), E3 (r = 0.3380, p < 0.05), and TTT (r = 0.2867, p < 0.05), respectively, by partial correlation analysis. In conclusion, BMD at different sites of the skeleton correlated with the level of different sex hormones. It seems that BMD at different sites of the body is controlled by different sex hormones. Whether this phenomenon should be considered in the choice of hormone replacement therapy, or in improving the BMD diagnostic standard, needs further study.

Adult↗

PubMed1999

Methamphetamine administration causes overexpression of nNOS in the mouse striatum.

The accumulated evidence suggests that the overproduction of nitric oxide (NO) is involved in methamphetamine (METH)-induced neurotoxicity. Using NADPH-diaphorase histochemistry, neuronal nitric oxide synthase (nNOS) and inducible nitric oxide synthase (iNOS) antibody immunohistochemistry, the possible overexpression of nNOS and iNOS was investigated in the brains of mice treated with METH. The number of positive cells or the density of positive fibers was assessed at 1 h, 24 h and 1 week after METH injections. There were no clear positive iNOS cells and fibers demonstrated in the brains of mice after METH treatment. In contrast, METH caused marked increases in nNOS in the striatum and hippocampus at 1 and 24 h post-treatment. The nNOS expression normalized by 1 week. There were no statistical changes in nNOS expression in the frontal cortex, the cerebellar cortex, nor in the substantia nigra. These results provide further support for the idea that NO is involved in the neurotoxic effects of METH.

Animals↗

PubMed1999

Null mutation of c-fos causes exacerbation of methamphetamine-induced neurotoxicity.

Methamphetamine neurotoxicity has been demonstrated in rodents and nonhuman primates. These neurotoxic effects may be associated with mechanisms involved in oxidative stress and the activation of immediate early genes (IEG). It is not clear, however, whether these IEG responses are involved in a methamphetamine-induced toxic cascade or in protective mechanisms against the deleterious effects of the drug. As a first step toward clarifying this issue further, the present study was thus undertaken to assess the toxic effects of methamphetamine in heterozygous and homozygous c-fos knock-out as well as wild-type mice. Administration of methamphetamine caused significant reduction in [(125)I]RTI-121-labeled dopamine uptake sites, dopamine transporter protein, and tyrosine hydroxylase-like immunohistochemistry in the striata of wild-type mice. These decreases were significantly exacerbated in heterozygous and homozygous c-fos knock-out mice, with the homozygous showing greater loss of striatal dopaminergic markers. Moreover, in comparison with wild-type animals, both genotypes of c-fos knock-out mice showed more DNA fragmentation, measured by the number of terminal deoxynucleotidyl transferase-mediated dUTP nick-end-labeled nondopaminergic cells in their cortices and striata. In contrast, wild-type mice treated with methamphetamine demonstrated a greater number of glial fibrillary acidic protein-positive cells than did c-fos knock-out mice. These data suggest that c-fos induction in response to toxic doses of methamphetamine might be involved in protective mechanisms against this drug-induced neurotoxicity.

Animals↗

PubMed1999

A synthetic peptide derived from human immunodeficiency virus type 1 gp120 downregulates the expression and function of chemokine receptors CCR5 and CXCR4 in monocytes by activating the 7-transmembrane G-protein-coupled receptor FPRL1/LXA4R.

Because envelope gp120 of various strains of human immunodeficiency virus type 1 (HIV-1) downregulates the expression and function of a variety of chemoattractant receptors through a process of heterologous desensitization, we investigated whether epitopes derived from gp120 could mimic the effect. A synthetic peptide domain, designated F peptide, corresponding to amino acid residues 414-434 in the V4-C4 region of gp120 of the HIV-1 Bru strain, potently reduced monocyte binding and chemotaxis response to macrophage inflammatory protein 1beta (MIP-1beta) and stromal cell-derived factor 1alpha (SDF-1alpha), chemokines that use the receptors CCR5 and CXCR4, respectively. Further study showed that F peptide by itself is an inducer of chemotaxis and calcium mobilization in human monocytes and neutrophils. In cross-desensitization experiments, among the numerous chemoattractants tested, only the bacterial chemotactic peptide fMLF, when used at high concentrations, partially attenuated calcium mobilization induced by F peptide in phagocytes, suggesting that this peptide domain might share a 7-transmembrane, G-protein-coupled receptor with fMLF. By using cells transfected with cDNAs encoding receptors that interact with fMLF, we found that F peptide uses an fMLF receptor variant, FPRL1, as a functional receptor. The activation of monocytes by F peptide resulted in downregulation of the cell surface expression of CCR5 and CXCR4 in a protein kinase C-dependent manner. These results demonstrate that activation of FPRL1 on human moncytes by a peptide domain derived from HIV-1 gp120 could lead to desensitization of cell response to other chemoattractants. This may explain, at least in part, the initial activation of innate immune responses in HIV-1-infected patients followed by immune suppression.

Acquired Immunodeficiency Syndrome↗

PubMed1999

Ceramide induces Bcl2 dephosphorylation via a mechanism involving mitochondrial PP2A.

Phosphorylation of Bcl2 at serine 70 is required for its potent anti-apoptotic function. We have recently shown that Bcl2 phosphorylation is a dynamic process that involves the protein kinase C alpha and protein phosphatase 2A (PP2A) (Ruvolo, P. P., Deng, X., Carr, B. K., and May, W. S. (1998) J. Biol. Chem. 273, 25436-25442; and Deng, X., Ito, T., Carr, B. K., Mumby, M. C., and May, W. S. (1998) J. Biol. Chem. 273, 34157-34163). The potent apoptotic agent ceramide can activate a PP2A, suggesting that one potential component of the ceramide-induced death signal may involve the inactivation of Bcl2. Results indicate that C2-ceramide but not inactive C2-dihydroceramide, was found to specifically activate a mitochondrial PP2A, which rapidly and completely induced Bcl2 dephosphorylation and correlated closely with ceramide-induced cell death. Using a genetic approach, the gain-of-function S70E Bcl2 mutation, which mimics phosphorylation, fails to undergo apoptosis even with the addition of high doses of ceramide (IC50 > 50 microM). In contrast, cells overexpressing exogenous wild-type Bcl2 were sensitive to ceramide at dosages where PP2A is fully active and Bcl2 would be expected to be dephosphorylated (IC50 = 14 microM). These findings indicate that in cells expressing functional Bcl2, the mechanism of death action for ceramide may involve, at least in part, a mitochondrial PP2A that dephosphorylates and inactivates Bcl2.

Animals↗

PubMed1999

T20/DP178, an ectodomain peptide of human immunodeficiency virus type 1 gp41, is an activator of human phagocyte N-formyl peptide receptor.

Human immunodeficiency virus type 1 (HIV-1) envelope protein gp41 mediates viral fusion with human host cells. The peptide segment T20/DP178, located in the C-terminus of the ectodomain of gp41, interacts with the N-terminal leucine zipper-like domain on gp41 to establish the fusogenic conformation of the virus. Synthetic T20/DP178 peptide is highly efficacious in inhibiting HIV-1 infection in vitro by disrupting the transformation of fusogenic status of viral gp41; thus, it has been proposed for clinical trial. We report that synthetic T20/DP178 is a chemoattractant and activator of human peripheral blood phagocytes but not of T lymphocytes. We further demonstrate that T20/DP178 specifically activates a seven-transmembrane, G-protein-coupled phagocyte receptor for N-formylated chemotactic peptides, formyl peptide receptor (FPR). Moreover, synthetic T20/DP178 analogs lacking N-terminal amino acids acted as FPR antagonists. Our results suggest that gp41 peptides regulate phagocyte function via FPR and identify a novel mechanism by which HIV-1 may modulate innate immunity.

Cells, Cultured↗

PubMed1999

Investigation on process parameters involved in preparation of poly-DL-lactide-poly(ethylene glycol) microspheres containing Leptospira Interrogans antigens.

Block copolymer, poly-DL-lactide-poly(ethylene glycol) (PELA) with 11.5% of poly(ethylene glycol) (PEG) content was prepared by bulk ring-opening polymerization using stannous chloride as initiator. PELA microspheres with entrapped Leptospira Interrogans antigens, outer membrane protein (OMP) were elaborated by solvent extraction method based on the formation of multiple w/o/w emulsion, and the resulting microspheres were characterized with respect to particle size, OMP entrapment and morphology characteristics. The purpose of the present study is to perform the optimization of preparative parameters for OMP-loaded PELA micropsheres to control particle size and improve the OMP encapsulation efficiency. Of all the parameters investigated, the polymer concentration of organic phase and the external aqueous phase volume play major roles on particle size, while the organic phase volume, internal aqueous phase volume and the addition of surfactant into the internal aqueous phase display considerable effects on OMP loading efficiency. A small volume of internal aqueous phase and intermediate volumes of organic phase and external aqueous phase were favorable to achieve micropsheres with a size of 1-2 microns and high antigen encapsulation efficiency (70-80%). In vitro OMP release profiles from PELA microspheres consist of a small burst release followed by a gradual release phase. The OMP release rate shows some relations with the porous and water-swollen inner structure of the microspheres matrix. The presence of surfactant in microspheres accelerates OMP release, but the OMP entrapment within microspheres shows limited effects on the release profile.

Antigens, Bacterial↗

PubMed1999

[A DNA probe suitable for the detection of chromosome 21 copy number in human interphase nuclei by fluorescence in situ hybridization].

OBJECTIVE: To prepare DNA probe which can be used to accurately detect chromosome 21 copy number in human interphase nuclei by fluorescence in situ hybridization (FISH). METHODS: A probe was produced by universal primer PCR from YAC clone 881D2 and characterized by FISH to metaphases and interphase nuclei of peripheral lymphocytes from 8 normal individuals and 5 patients suffering from trisomy 21. RESULTS: A DNA probe was produced and its characteristics were :(1) Most of the probes ranged in size from 350bp to 750bp; (2) The hybridization signals of the probes were located near centromere on long arm of human chromosome 21; (3) In 1524 metaphases scored, about 99.95% of hybridization signals were located on chromosome 21; (4) The signals were very bright and recognizable easily in both metaphases and interphases nuclei; (5) The expected copy number of chromosome 21 was detected by FISH with the probe in more than 98.40% of interphase nuclei and 99.60% of metaphases. CONCLUSION: The DNA probe reported here is suitable for the detection of chromosome 21 copy number in interphase nuclei and for the study of segregation of chromosome 21 during mitoses of human lymphocytes in culture.

Cell Nucleus↗