Search PubMed⌕ Search

Biomedical subjects

H Zhou

Publications and source records attributed to H Zhou.

At least 145 records · Page 8Linked to original sources
PubMed2001

Impact of polymer hydrophobicity on the properties and performance of DNA sequencing matrices for capillary electrophoresis.

To elucidate the impact of matrix chemical and physical properties on DNA sequencing separations by capillary electrophoresis (CE), we have synthesized, characterized and tested a controlled set of different polymer formulations for this application. Homopolymers of acrylamide and N,N-dimethylacrylamide (DMA) and copolymers of DMA and N,N-diethylacrylamide (DEA) were synthesized by free radical polymerization and purified. Polymer molar mass distributions were characterized by tandem gel permeation chromatography - laser light scattering. Polymers with different chemical compositions and similar molar mass distributions were selected and employed at the same concentration so that the variables of comparison between them were hydrophobicity and average coil size in aqueous solution. We find that the low-shear viscosities of 7% w/v polymer solutions decrease by orders of magnitude with increasing polymer hydrophobicity, while hydrophilic polymers exhibit more pronounced reductions in viscosity with increased shear. The performance of the different matrices for DNA sequencing was compared with the same sample under identical CE conditions. The longest read length was produced with linear polyacrylamide (LPA) while linear poly-N,N-dimethylacrylamide (PDMA) gave approximately 100 fewer readable bases. Read lengths with DMA/DEA copolymers were lower, and decreased with increasing DEA content. This study highlights the importance of polymer hydrophilicity for high-performance DNA sequencing matrices, through the formation of robust, highly-entangled polymer networks and the minimization of hydrophobic interactions between polymers and fluorescently-labeled DNA molecules. However, the results also show that more hydrophobic matrices offer much lower viscosities, enabling easier microchannel loading at low applied pressures.

Acrylamides↗
PubMed2001

Efficacy and mechanisms of action of rmB7.2-Ig as an antitumor agent in combination with Adriamycin and Cytoxan chemotherapy.

The efficacy of chemotherapy for cancer is often limited by toxicity. Immune approaches to cancer immunotherapy, while promising for specificity and long-term protection, have not typically proven potent enough to generate significant therapeutic responses. We have shown therapeutic benefit using recombinant murine B7.2-Ig (rmB7.2-Ig) in murine tumor models. Efficacy was dependent on immune activity and was not associated with toxicity. Recently, the efficacy of rmB7.2-Ig was demonstrated in leukemia tumor models in combination with chemotherapeutic agents. To further explore the potential of this approach, we evaluated the efficacy in solid tumor models of rmB7.2-Ig given in combination with chemotherapeutics commonly used in clinical practice, testing the effects of dose and schedule. RmB7.2-Ig in combination with some chemotherapeutics enhances the activity and efficacy of reduced chemotherapeutic doses. However, the relative timing of chemotherapy and rmB7.2-Ig dosing can be important. Investigation of mechanisms of action based on histological studies suggests that inflammatory as well as T cell mechanisms comprise the response. Additional studies of mice deleted of B7.1, B7.2, and CTLA-4 suggest that the enhanced response induced by rmB7.2-Ig may not be mediated through CD28 ligation alone. The efficacy suggests potential for recombinant human B7.2-Ig as an adjuvant to chemotherapy in promoting immune-mediated mechanisms to augment the activity of chemotherapy.

Animals↗
PubMed2001

A Cre-expressing cell line and an E1/E2a double-deleted virus for preparation of helper-dependent adenovirus vector.

Adenoviral vectors are attractive for the delivery of transgenes into mammalian cells because of their efficient transduction, high titer, and stability. The major concerns with using E1-deleted adenoviral vectors in gene therapy are the pathogenic potential of the virus backbone and the leaky viral protein synthesis that leads to host immune responses and a short duration of transgene expression. Helper-dependent (HD) adenoviral vectors that are devoid of all viral protein-coding sequences have significantly increased the safety and reduced the immunogenicity of these vectors. Currently available HD vectors depend on an E1-deleted adenovirus as a helper to provide viral proteins in trans. As a consequence, contamination with helper virus cannot be avoided in the HD vector preparation though it can be decreased to 0.01% using a Cre/loxP mechanism. Since the presence of E1-deleted helper virus may have substantial unwanted effects, we have developed a new Cre-expressing cell line based on an E1- and E2a-complementing cell. This new cell line can efficiently cleave the packaging region in the helper virus genome. We have also developed an E1 and E2a double-deleted helper virus. By using the CreE cell with the helper virus deleted in both the E1 and the E2a genes it may be possible to further improve the safety of the vectors.

Adenoviridae↗
PubMed2001

The binding ability analysis of the normal VLDL receptor and its mutant.

The ligand-binding domain of VLDL receptor contains eight imperfectly similar repeats. To discuss the contribution of each repeat to ligand binding, the RT-PCR technique was used to clone the VLDLR-cDNA from the heart muscle of Chinese people. Two recombinants were further constructed, which contained the full-length cDNA of VLDLR and the mutant lacking repeats 1-5. CHO cell line was transfected with two recombinants. The expression of VLDLR gene could be detected by RT-PCR from the CHO cells transfected with pCD-VR. The results of binding experiments showed that the ability of the CHO cells transfected with the full-length cDNA of VLDL-R binding DiI-labeled beta-VLDL was higher than that of the CHO cells transfected with the mutant. Our findings indicated that human VLDL-R gene could be expressed effectively on CHO cells, and the receptor was almost inactivated when repeats 1-5 were deleted.

Animals↗
PubMed2001

The mechanical study of vascular endothelial growth factor on the prevention of restenosis after angioplasty.

The mechanism of vascular endothelial growth factor (VEGF) on the prevention of restenosis after angioplasty was investigated. The cultured vascular endothelial cells (VEC) were incubated with the conditioned medium (CM) from vascular smooth muscle cells (VSMC) infected with recombinant adenoviruses containing the hVEGF165 gene. To observe the effects of VEGF on proliferation and NO, ET, 6-keto-PGF1 alpha secretion of VEC, WST-1 method, Griess method and radioimmunoassay were used respectively. The PDGF-B mRNA transcription in VECs was detected by RT-PCR. It was showed that NO, 6-keto-PGF1 alpha and OD value were markedly increased in a dose-dependent manner in the VEGF-treated groups as compared with those in the control group, while ET and PDGF-B mRNA were significantly decreased in the VEGF-treated groups (P < 0.05 or P < 0.01). Adenovirus vector mediated hVEGF165 gene could promote the proliferation of VECs and improve NO, PGI2 secretion, inhibit ET secretion and PDGF-B mRNA transcription in the VECs. The above results offered further theoretical evidence for VEGF on the prevention of restenosis after angioplasty.

6-Ketoprostaglandin F1 alpha↗
PubMed2001

Postnatal development of presynaptic receptors that modulate noradrenaline release in mice.

The objective of the study was to clarify the postnatal development of the following transmitter release-modulating receptors of noradrenergic neurons in mice: alpha2-adrenoceptors, muscarinic, opioid and cannabinoid receptors (inhibitory), beta-adrenoceptors and receptors for angiotensin II and bradykinin (facilitatory). Wildtype (NMRI) and in some cases alpha2A/D-adrenoceptor-deficient mice aged 1 day (P1) or 8-16 weeks (adults) were used. Hippocampal and occipito-parietal cortex slices and sympathetically innervated tissues (atria and vas deferens) were preincubated with [3H]-noradrenaline and then superfused and stimulated electrically. Stimulation led to distinct increases in tritium efflux which were abolished by tetrodotoxin or removal of calcium. Concentration-response curves of appropriate agonists and in the case of alpha2-autoreceptors antagonists were determined. For beta-adrenoceptors and angiotensin receptors, the interaction of agonists with antagonists was also examined. Results demonstrate that alpha2A/D-autoreceptors operate already at P1 whereas nonalpha2A/D-autoreceptors, presumably alpha2C, develop later. Of the various heteroreceptors, those of brain noradrenergic neurons (OP3 and ORL1) modulate the release of [3H]-noradrenaline at least as effectively at P1 as in adults. Those of peripheral sympathetic neurons (muscarinic, probably mainly M2, OP1, OP2, OP3, CB1, AT1 and B1), in contrast, operate less effectively or not at all at P1, with one exception: beta2-adrenoceptors increase the release of [3H]-noradrenaline (atria) to the same extent, irrespective of age. Overall, results indicate that brain and peripheral noradrenergic neurons release their transmitter already shortly after birth. Presynaptic receptor mechanisms mature differentially in the brain and the periphery. Moreover, the various presynaptic receptors differ in their postnatal development and may play differential roles at different ages.

Animals↗
PubMed2001

Lumbar vertebral cancellous bone is capable of responding to PGE2 treatment by stimulating both modeling and remodeling-dependent bone gain in aged male rats.

Previously we found that PGE2 3 mg/kg in 20-month-old male rats induced massive bone formation mainly by modeling dependent bone gain in cortical bone. It is not known whether cancellous bone will respond similarly; thus, we evaluated the effect of PGE2 on cancellous bone of the same aged rats. Thirty-four 20-month-old Wistar male rats were given PGE2 (3 mg/kg/day) or vehicle subcutaneously for 10 and 30 days. Double fluorescent labels were injected 9 and 2 days prior to the sacrifice. Histomorphometry was performed on 1% toluidine blue stained and unstained sagittal sections of lumbar vertebral bodies. The results demonstrated that 10-day PGE2 treatment increased osteoprogenitor cells, osteoblasts (x 2-fold), osteoid (x 4.5-fold), woven bone formation (0.04%), and 40% more trabecular area; it stimulated modeling (x 2-fold) and remodeling-dependent (x 1.5-fold) bone formation with increase of mineralization lag time (MLT, x 7.5-fold). Thirty-day treatment sustained increases in osteoblast numbers, modeling and remodeling-dependent bone formation and further stimulated woven bone formation (6.6%), turnover (x 3-fold), and trabecular area and number (x 2-fold). Osteoprogenitor cells were undetectable along with 70% less osteoid area compared with 10-day treatment but still was 1.5-fold higher than aging controls. MLT returned to aging control level. It was concluded that the aged cancellous bone of 20-month-old male Wistar rat retains a capability of responding to the anabolic effect of PGE2. Osteoblastogenesis and enhanced modeling and remodeling-dependent woven or lamellar formation contribute to this anabolic action. Bone formation differed in that the endocortical surface of cortical bone was stimulated mainly by modeling whereas both modeling and remodeling-dependent bone gain were equally stimulated at the trabecular surface of the lumbar vertebral body.

Animals↗
PubMed2001

Solid-cystic papillary tumor of the pancreas in children.

Solid-cystic papillary tumor (SCPT) of the pancreas is a rare neoplasm in children. The current study attempted to estimate the incidence and possible pathological origin of the tumor. Clinicopathologic features of the children under the age of 16 years with pancreatic tumors managed in a single institution between January 1993 and November 1999 were reviewed. Representative blocks of SCPT specimens were immunostained for neuron-specific enolase (NSE) chromogrannin, synaptophysin, insulin, glucagon, somatostatin, and gastrin. There were three SCPTs, two pancreatic endocrine tumors, and one acinar cell carcinoma during the study period. The estimated yearly incidence in the referral area of 2 million population is about 0.01 pediatric SCPT per year per 100,000 population. The children underwent surgical removal of the tumors. Postoperatively, they were followed up for 6 months to 4 years and were well. Immunostaining for NSE, chromogranin, synaptophysin, insulin, somatostatin, and gastrin was negative in all cases. SCPT may thus be the most common pancreatic tumor in the Asian pediatric population. The pathological origin of the tumor remains unclear and requires further investigations.

Adolescent↗
PubMed2001

Immunohistochemical patterns of human liver sinusoids under different conditions of pathologic perfusion.

This study reports the effects of altered hepatic perfusion on the sinusoidal bed and the phenotypic characteristics of sinusoidal endothelial cells (SECs). Sinusoids were studied by the application of endothelial cell markers (CD31, CD34, CD105, and ATZ 11) in lesions with localized increased perfusion (liver cell adenoma, focal nodular hyperplasia, and macroregenerative nodule), in chronic congestion, in decreased portovenous inflow (portal vein thrombosis), and in decreased arteriohepatic perfusion (obliterative arteriopathy in chronic allograft rejection). SECs react in a sensitive and uniform way to all investigated conditions of different pathologic liver perfusion: expression of CD31, CD34, and ATZ 11 by SEC is found in inflow areas, CD105-positive SECs are found at the end of the sinusoidal blood stream. This blood flow-orientated phenotypic shift of SECs was accompanied by a perisinusoidal accumulation of activated hepatic stellate cells and collagen IV. These findings are helpful in liver biopsies and provide new insights into the angioarchitecture of benign nodular lesions.

Adenoma↗
PubMed2001

Cancellous bone of aged rats maintains its capacity to respond vigorously to the anabolic effects of prostaglandin E2 by modeling-dependent bone gain.

The present study examined the early effects of prostaglandin (PG)E2 on proximal tibial metaphyses of 20-month-old Wistar male rats. PGE, was given to intact rats for 10 and 30 days at 3mg/kg/day. After multiple in vivo fluorochrome labeling, undecalcified longitudinal sections were subjected to analysis of bone histomorphometry and classification of the contour of the cement line in bone formation units. The latter was used to classify bone formation units into modeling, remodeling and uncertain units. After 10 days of treatment, there was a 2% increase in woven bone formation with the appearance of osteoprogenitor cells and increases in the number of osteoblasts (649%) and osteoid (375%) surfaces. Remodeling and modeling units increased by 56% and 429%. respectively. After 30 days of treatment, there was an increase of 212% of total trabecular bone mass, 60% of which was woven bone. In addition, there were increases in labeling surface (147%), mineral apposition rate (760%), bone formation rates tissue area (BFR/T.Ar, 1920%; BFR/B.Pm, 343%), and bone turnover (BFR/B.Ar, 426%). Osteoblasts and osteoid production at 30 days were 29% and 58% less than at 10 days post-treatment. Modeling and remodeling activity did not differ from that seen at 10 days. In addition, PGE2 treatment tended to stimulate the closing of growth plates and decrease the fatty marrow area. We conclude that the aged skeleton was able to respond vigorously to PGE2 treatment. Massive osteoprogenitors cells, and osteoid and osteoblast formations were observed within 10 days. and dramatic woven and lamellar bone formation was seen at 30 days post-treatment. The anabolic effects were driven mainly by modeling.

Aging↗
PubMed2001

The cardiovascular actions of omapatrilat in spontaneously hypertensive rats.

Omapatrilat is a newly developed vasopeptidase inhibitor that inhibits both angiotensin-converting enzyme (ACE) and neutral endopeptidase and has potent antihypertensive efficacy. However, the specific effect of omapatrilat on cardiac function and left ventricular hypertrophy with hypertension remains controversial. Therefore, we investigated the effect of omapatrilat on blood pressure, cardiac hypertrophy, and cardiac function in spontaneously hypertensive rats (SHR). Studies were performed in SHR that received vehicle (n = 9), omapatrilat (n = 10), or fosinopril (ACE inhibitor, n = 7) by daily gavage for 56 days. Systolic blood pressure (SBP) and mean blood pressure (MBP) were measured by tail plethysmography. Left ventricular fractional shortening and left ventricular mass were measured by echocardiography at day 56. Omapatrilat and fosinopril significantly decreased SBP and MBP from day 1 through day 56, and omapatrilat markedly reduced SBP and MBP compared with fosinopril from day 21 to day 56. Although both omapatrilat and fosinopril decreased left ventricular mass and left ventricular mass-to-body weight ratio with increased LV fractional shortening, omapatrilat had a more potent effect on the reduction of left ventricular mass and improvement of cardiac function. This study shows that in SHR, omapatrilat mediated a potent and stable antihypertensive effect and a reduction in left ventricular mass with improvement of cardiac function, compared with ACE inhibition alone.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2001

Stretching single-stranded DNA: interplay of electrostatic, base-pairing, and base-pair stacking interactions.

Recent single-macromolecule observations revealed that the force/extension characteristics of single-stranded DNA (ssDNA) are closely related to solution ionic concentration and DNA sequence composition. To understand this, we studied the elastic property of ssDNA through the Monte Carlo implementation of a modified freely jointed chain (FJC), with electrostatic, base-pairing, and base-pair stacking interactions all incorporated. The simulated force-extension profiles for both random and designed sequences have attained quantitative agreements with the experimental data. In low-salt solution, electrostatic interaction dominates, and at low forces, the molecule can be more easily aligned than an unmodified FJC. In high-salt solution, secondary hairpin structure appears in ssDNA by the formation of base pairs between complementary bases, and external stretching causes a hairpin-coil structural transition, which is continuous for ssDNA made of random sequences. In designed sequences such as poly(dA-dT) and poly(dG-dC), the stacking potential between base pairs encourages the aggregation of base pairs into bulk hairpins and makes the hairpin-coil transition a discontinuous (first-order) process. The sensitivity of elongation to the base-pairing rule is also investigated. The comparison of modeling calculations and the experimental data suggests that the base pairing of single-stranded polynucleotide molecules tends to form a nested and independent planar hairpin structure rather than a random intersecting pattern.

Base Pairing↗
PubMed2001

Effects of DL111-IT or combined with RU486 on uterine polyamines biosynthesis in rats during early gestation.

DL111-IT, a non-hormonal contragestional agent, revealed synergistic effects in combination with mifepristone (RU486) in some species. The present study was undertaken to clarify the role of DL111-IT when used alone or plus RU486 on uterine polyamines biosynthesis, histologic alteration of decidual cells, and antifertility activity in rats. The levels of polyamines in pregnant rat uterus were determined by formed benzoyl chloride derivatives of polyamines for RP-HPLC. The results showed that all the treated groups including DL111-IT 2.8 mg. kg(-1). d(-1), RU486 3.0 mg. kg(-1). d(-1), and DL111-IT 0.56 mg. kg(-1). d(-1) plus RU486 0.6 mg. kg(-1). d(-1) caused 100% early pregnancy arrest. Uterine putrescine, spermidine, and spermine levels in comparison with vehicle control were declined significantly from d7 of gestation (1 day after treatment) to d9 or d14 (3 days or 8 days after treatment) by Duncan's multiple range test, and accompanied by histologic alterations, edema, degeneration and dissolution of decidual cells with nuclei indefinite in appearance on d8 of gestation (2 days after treatment). The combined administration at lower doses caused the most injury. The data verified that the decrease in uterine polyamine levels and subsequent decidual cells injuries were the critical role of early pregnancy arrest induced by DL111-IT or RU486. The two compounds used in combination with lower dosages revealed greatly synergistic effects.

Abortifacient Agents, Nonsteroidal↗
PubMed2001

DNA-binding and photocleavage studies of cobalt(III) mixed-polypyridyl complexes containing 2-(2-chloro-5-nitrophenyl)imidazo [4,5-f][1,10]phenanthroline.

The ligand 2-(2-chloro-5-nitrophenyl)imidazo[4,5-f][1,10]phenanthroline(CNOIP) and its complexes [Co(bpy)(2)(CNOIP)](3+) (1) and [Co(phen)(2)(CNOIP)](3+) (2) (bpy=2,2'-bipyridine; phen=1,10-phenanthroline) have been synthesized and characterized. Binding of the two complexes with calf thymus DNA has been investigated by spectroscopic methods, cyclic voltammetry, viscosity, and electrophoresis measurements. The experimental results indicate that both complexes bind to DNA through an intercalative mode. In comparison with their parent complexes containing PIP ligand (PIP=2-phenylimidazo[4,5-f][1,10]phenanthroline), the introduction of NO(2) and Cl groups to the PIP ligand decreased the binding affinity of complexes 1 and 2 to CT DNA. Both complexes have also been found to promote the photocleavage of plasmid pBR 322 DNA, the hydroxyl radical (OH*) is suggested to be the reactive species responsible for the cleavage.

Cobalt↗
PubMed2001

Cytogenetic-clinicopathologic correlations in rhabdomyosarcoma: a report of five cases.

Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in children younger than the age of 15 years. Histologically, RMS can be subdivided into two major subtypes; embryonal (E-RMS) and alveolar (A-RMS) rhabdomyosarcoma, with E-RMS being the more common. Although cytogenetic and molecular genetic findings have been reported extensively for RMS, clinicopathologic-genetic correlations among these tumors have not been reported in detail. In this report, we correlate the cytogenetic findings, including fluorescence in situ hybridization and spectral karyotyping, with pathologic findings and outcome for five RMS, including two A-RMS, one E-RMS, one botryoid RMS, and one anaplastic nonclassified RMS (N-RMS). The findings in A-RMS and E-RMS generally were consistent with previous reports; however, gain of chromosome 7 in A-RMS and gain of chromosome 9 segments in E-RMS observed here have seldom been reported in the literature. Importantly, the botryoid RMS had a cytogenetic profile similar to other types of E-RMS. An add(11)(q21) observed in this tumor, together with a t(8;11)(q12 approximately 13;q21) reported previously, indicates that 11q21 rearrangements may be nonrandomly related to botryoid RMS. In addition, the N-RMS expressed a cytogenetic pattern similar to that observed in E-RMS, thus providing genetic evidence that anaplastic N-RMS is a variant of E-RMS. Finally, these cases provide cogent evidence for the diagnostic and prognostic significance of the pathologic-genetic classification of RMS.

Adolescent↗
PubMed2001

Solution and chip arrays in protein profiling.

The industrialization of proteomics demands reproducible, robust and high-throughput profiling technologies that current two-dimensional gel electrophoresis cannot achieve. New technologies in protein arrays, either on chips or with self-encoded elements in solution, hold much promise for interrogating the diverse and immense proteome.

Biosensing Techniques↗
PubMed2001

Role of proline, glycerol, and heparin as protein folding aids during refolding of rabbit muscle creatine kinase.

Aggregation of 3 M guanidine hydrochloride denatured creatine kinase (ATP: creatine N-phosphotransferase, EC 2.7.3.2) occurs after dilution into the refolding solution. Proline, glycerol and heparin sodium act as folding aids which can effectively inhibit aggregation of creatine kinase during refolding. Proline at 1 M concentration, glycerol at 10% concentration and heparin at 25 mg/ml not only completely prevented creatine kinase aggregation but also enabled the creatine kinase to return to its native state as well as to recover most of its native activity. The reactivity after the aggregation was completely blocked by the presence of each folding aid reached 65-80% of the native activity. Results of turbidity, activity, intrinsic fluorescence and 1-anilinonaphthalene-8-sulfonate binding fluorescence measurements suggested that the effect of heparin differs from that of proline and glycerol in its artificial chaperone-like behavior. Heparin may bind with creatine kinase both in the native state and during the refolding course. The results showed that this heparin-creatine kinase complex favorably restored the creatine kinase reactivity.

Anilino Naphthalenesulfonates↗