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D Zhang

Publications and source records attributed to D Zhang.

At least 541 records · Page 30Linked to original sources
PubMed1995

Chromosomes initiate spindle assembly upon experimental dissolution of the nuclear envelope in grasshopper spermatocytes.

Chromosomes are known to enhance spindle microtubule assembly in grasshopper spermatocytes, which suggested to us that chromosomes might play an essential role in the initiation of spindle formation. Chromosomes might, for example, activate other spindle components such as centrosomes and tubulin subunits upon the breakdown of the nuclear envelope. We tested this possibility in living grasshopper spermatocytes. We ruptured the nuclear envelope during prophase, which prematurely exposed the centrosomes to chromosomes and nuclear sap. Spindle assembly was promptly initiated. In contrast, assembly of the spindle was completely inhibited if the nucleus was mechanically removed from a late prophase cell. Other experiments showed that the trigger for spindle assembly is associated with the chromosomes; other constituents of the nucleus cannot initiate spindle assembly in the absence of the chromosomes. The initiation of spindle assembly required centrosomes as well as chromosomes. Extracting centrosomes from late prophase cells completely inhibited spindle assembly after dissolution of the nuclear envelope. We conclude that the normal formation of a bipolar spindle in grasshopper spermatocytes is regulated by chromosomes. A possible explanation is an activator, perhaps a chromosomal protein (Yeo, J.-P., F. Alderuccio, and B.-H. Toh. 1994a. Nature (Lond.). 367: 288-291), that promotes and stabilizes the assembly of astral microtubules and thus promotes assembly of the spindle.

Animals↗
PubMed1995

HIV type 1 protease activation of NF-kappa B within T lymphoid cells.

NF-kappa B is a nuclear protein of the rel oncogene family capable of enhancing transcription of several cellular genes, including IL-2 and the IL-2 receptor, and viral genes transcribed from the HIV-1 LTR. It has been reported that HIV-1 protease may cleave the NF-kappa B precursor to its active form in vitro. In this study the effects of HIV protease on NF-kappa B precursor activation were examined in Jurkat T cells by introducing a protease expression vector into the cells. Increased NF-kappa B activity was observed and this increased activity was blocked by a specific inhibitor of the viral protease. Viral transcription, as measured using LTR-CAT assays, was only slightly enhanced in the HIV-protease expressing cells, while secretion of IL-2 and expression of the IL-2 receptor were not affected. The limited activation of NF-kappa B by HIV protease appears unlikely to have a significant effect on virus expression or T cell function.

Base Sequence↗
PubMed1995

A humanized, bispecific immunoadhesin-antibody that retargets CD3+ effectors to kill HIV-1-infected cells.

We have developed a humanized, bispecific immunoadhesin-antibody (BsIAb) that targets and kills HIV-infected cells. Comprised of CD4-IgG and humanized anti-CD3-IgG, this BsIAb is bifunctional. First, in targeting, it exploits the natural affinity of CD4 for gp120 to target the BsIAb to HIV-infected cells, and second, it recruits and activates, through its anti-CD3 moiety, cytotoxic T lymphocytes (CTL) to lyse target cells in a non-MHC restricted manner. To produce purified BsIAb from supernantants of transfected mammalian cells, we designed a three-step recovery scheme based on the structural elements of this heterotrimeric protein. The ability of purified BsIAb to specifically lyse HIV-infected target cells was demonstrated using CTL from two different sources: whole peripheral blood lymphocyte (PBL) fractions and pure CTL preparations. In contrast, a human anti-gp120 antibody mediated lysis of HIV-infected target cells only with PBL fractions and not with purified CTL. Moreover, lysis observed in the presence of the human anti-gp120 antibody was completely blocked in the presence of human serum (which competes for Fc gamma receptor binding), whereas BsIAb-mediated lysis of target cells was not affected. We measured the monovalent affinities of BsIAb for HIV-gp120 on infected cells and for CD3 epsilon on CTL. Relative to the bivalent parent molecules, CD4/gp120 affinity in the BsIAb is unchanged, whereas anti-CD3/CD3 is substantially decreased. We further demonstrated by fluorescence microscopy that physical association of CD3+ cells with gp120-expressing cells occurs only in the presence of BsIAb. Thus, the cytocidal activity of BsIAb in the presence of serum reflects its unique ability to recruit CTL as effector cells and highlights a potentially important advantage of this type of construct over antibodies for HIV-directed therapy.

Antibodies, Bispecific↗
PubMed1995

Functional CD4+ T cell subsets defined by expression of CD45RC and NTA260 antigens and age-associated polarization in murine lupus.

Using two mAb, one specific to the alternative exon 6-dependent epitope of CD45 molecules (JH6.2) and one a natural thymocytotoxic autoantibody (NTA) with an unknown reactive epitope (NTA260), we subdivided splenic CD4+ T cells from 2-month-old BALB/c mice into five phenotypically distinct subsets. CD45RC+NTA260- (S I) cells were phenotypically analogous to CD4+ T cells predominating in newborn mice and produced a significant amount of IL-2, but not so IL-4, IL-10 or IFN-gamma when stimulated with immobilized anti-CD3 mAb in vitro. They appeared to consist mainly of naive ThP cells. The CD45RC+NTA260+ (S II) subset also produced IL-2, but not other cytokines; however, the IL-2 levels produced were much higher than seen with the S I subset, thereby suggesting the predominance of further maturated ThP cells. The CD45RC-NTA260+ (S III) subset mainly produced IL-4, IL-10, IFN-gamma and less IL-2, and contained memory cells that helped the secondary antibody response to a recall antigen, and hence contained Th2 and probably a mixture of Th0 and Th1 cells. The CD45RC-NTA260- (S IV) subset was a poor responder to the immobilized anti-CD3 mAb. The CD45RCbrightNTA260dull (S V) subset consisted of a small number of cells that were phenotypically analogous to activated CD4+ T cells. While an age-associated decrease in the proportion of S I and less markedly in S II and in turn increase in S III subsets of CD4+ T cells occurred in normal BALB/c mice, autoimmune disease-prone (NZB x NZW)F1 mice showed a marked age-associated decrease in the proportion of not only S I, II but also III subsets. As aged (NZB x NZW)F1 mice carry CD4+ T helper cells for IgG anti-DNA antibody production, such age-associated polarization to the S IV subset appears to be critical in the pathogenesis of autoimmune disease in these mice.

Aging↗
PubMed1995

Regulation of NIH-3T3 cell G1 phase transit by serum during exponential growth.

The proliferation rate of mammalian cells is regulated normally in the G1 phase of the cell cycle. During this phase, it is convenient to assign positive and negative roles to the molecular programs that regulate the duration of G1 and the phase transition from G1 to S phase. Density-dependent inhibition of cellular proliferation results in an increase in the duration of G1. This form of regulation is due to both secreted factors and cell-cell contact. Serum is mitogenic to a variety of mammalian cell types. Because quiescent cells enter S phase as a result of serum addition to culture media, serum is usually regarded as a source of positive regulatory growth factors. We have measured the length of the G1, S and G2+M phases of NIH 3T3 cells during exponential growth as a function of cell density and serum concentration. The G1 length increases during exponential growth as a function of density while S and G2+M are relatively constant. Further, this increase in G1 phase time, or density mediated negative regulation, is inhibited by increasing serum concentration. This phenotype is saturable between 10% to 20% serum. Serum concentrations above 2.5% are able to increase the rate of cell cycling (decrease the G1 phase time) by inhibiting density dependent negative regulation of NIH 3T3.

3T3 Cells↗
PubMed1995

Immunological studies on an Onchocerca volvulus intermediate-filament protein.

We report the complete sequence of the cDNA encoding an intermediate filament (IF) protein from Onchocerca volvulus. The OVIF cDNA encodes a protein of 613 amino acid residues, which has a predicted molecular weight of approximately 70 kD. The size of the protein encoded by the OVIF cDNA corresponds well with estimates obtained in Western blotting experiments, but these same experiments suggest that Onchocerca sp. may contain at least two IF proteins. To identify the domain(s) of the OVIF protein responsible for immunogenicity in human filariasis patients, fragments of the OVIF cDNA were subcloned into the appropriate pGEX vector and Western blots of the corresponding fusion proteins probed with human sera. Pooled sera from general onchocerciasis or Bancroftian filariasis patients reacted only with the C-terminal region of the OVIF protein, whereas sowda onchocerciasis sera reacted 1-2 orders of magnitude more strongly and with a number of other epitopes. Immunolocalization experiments implied that the OVIF protein is associated with both muscle and a number of specific membrane layers. These studies provide the basis for evaluation of the protective potential of the OVIF protein.

Amino Acid Sequence↗
PubMed1995

The small GTP-binding protein, rho p21, is involved in bone resorption by regulating cytoskeletal organization in osteoclasts.

Rho protein (rho p21), a p21ras-related small guanine nucleotide binding protein, regulates cytoskeletal organization in a number of different types of cells. Evidence has indicated that Clostridium botulinum-derived ADP-ribosyltransferase (C3 exoenzyme) specifically ADP-ribosylates rho p21 at Asn41 and renders it functionally inactive. In this study, we examined the involvement of rho p21 in osteoclastic bone resorption using the C3 exoenzyme. When osteoclast-like multinucleated cells obtained from cocultures of mouse osteoblastic cells and bone marrow cells were placed on dentine slices, they formed ringed structures of podosomes containing F-actin (corresponding to the clear zone) within 8 hours. Many resorption pits were formed on dentine slices after culture for 24 hours. The C3 exoenzyme at 0.15-10 micrograms/ml added to the culture medium disrupted the ringed structure of podosomes in osteoclast-like cells in a dose-dependent manner. Correspondingly, pit formation by osteoclast-like cells on dentine slices was dose-dependently inhibited also by adding the C3 exoenzyme. Microinjection of the C3 exoenzyme into osteoclast-like cells placed on culture dishes completely disrupted the ringed podosome structure within 20 minutes. The amount of the rho p21 which was ADP-ribosylated by the C3 exoenzyme in vitro was much greater in purified osteoclast-like cells than in osteoblastic cells. Prior exposure of the purified osteoclast-like cell preparation to the C3 exoenzyme in vivo markedly decreased the amount of unribosylated rho p21. This indicated that the C3 exoenzyme incorporated into osteoclast-like cells effectively ADP-ribosylates rho p21 in vivo.(ABSTRACT TRUNCATED AT 250 WORDS)

Actins↗
PubMed1995

Risk factors for lower extremity amputation in persons with diabetes.

OBJECTIVE: To determine the predictors of lower extremity amputation (LEA) in a cohort of persons with diabetes (primarily non-insulin-dependent). RESEARCH DESIGN AND METHODS: We conducted a nested case-control study among 10,068 patients from a large health maintenance organization who reported a diagnosis of diabetes at a multiphasic health checkup (MHC) (baseline) between 1964 and 1984. Average length of follow-up after baseline was 13.2 years. Case patients were 150 cohort members with a first, nontraumatic LEA after baseline. Control subjects were 278 cohort members who did not experience an LEA during follow-up, matched to patients on age, sex, and year of baseline MHC. The presence of diabetes at baseline was verified by chart review for both patients and control subjects. Cardiovascular disease risk factors were obtained at the baseline MHC; glucose control, other diabetes-related variables, preventive services, and other complications were obtained from chart review. RESULTS: Level of glucose control (P < 0.0001), duration of diabetes (P = 0.04), and baseline systolic blood pressure (P = 0.004) were independent predictors of amputation, as were microvascular complications (retinopathy, neuropathy, and nephropathy). History of stroke, but not myocardial infarction, was also independently predictive; type of diabetes, cigarette smoking, and total cholesterol level were not. Being African-American was unrelated to amputation risk in univariate or multivariate analyses in this insured population. CONCLUSIONS: LEA shares a risk factor profile with other microvascular complication of diabetes. Thus, control of blood glucose and blood pressure should reduce risk for amputation. African-Americans do not appear to be at increased risk for diabetes-related amputation when access to medical care is comparable.

Black or African American↗
PubMed1995

Physician and patient prevention practices in NIDDM in a large urban managed-care organization.

OBJECTIVE: To examine physician and patient adherence to prevention guidelines in non-insulin-dependent diabetes mellitus (NIDDM) with attention to possible differences in adherence by patient race or ethnicity. RESEARCH DESIGN AND METHODS: We performed a cross-sectional chart review study of prevention practices, complications, and risk factors in 378 NIDDM patients (at least 5 years known duration) who were Permanente Medical Care Program, Oakland, CA. There were 232 blacks, 81 whites, 29 Hispanics, and 36 members of other races/ethnicities. RESULTS: Age- and duration-adjusted prevalence of 14 complications was low and, with the exception of diabetic retinopathy, did not differ significantly by race. An eight-point prevention score that reflected recommended use of glucose, HbA1c, high-density lipoprotein/total cholesterol, blood pressure and proteinuria testing, ophthalmology a and foot examinations, and diabetes education during a 2-year period did not differ by race/ethnicity (P = 0.36). The mean score (4.9 +/- 1.6) indicated that on average, five of eight guidelines were performed appropriately. Compliance was poorest for annual proteinuria checks (32.2%). No differences were noted by race/ethnicity in referrals to ophthalmology, weight reduction, or smoking cessation or in missed appointments or failure to keep referral visits. CONCLUSIONS: The absence of racial differences in either prevention practices or complication rates in this insured prepaid setting suggests that improved access to preventive services may be effective in reducing such differences nationally. However, adherence to several guidelines was < or = 50%, indicating that physicians are not sufficiently convinced of the necessity for these prevention measures.

Black or African American↗
PubMed1995

[Inhibition of hepatitis B viral gene expression and replication in vitro by targeted antisense oligonucleotides].

We chose the 2.2. 15 cells as an in vitro cell culture assay system, and identified the surface antigen subtype of hepatitis B virus (HBV) DNA in the cells, by using the amplification of polymerase chain reaction and directed sequencing of amplified products. According to the result of the sequencing, a 16-mer phosphorothioate analogue of the antisense oligonucleotide (PS-ASON) directed against the HBV U5-unique region was synthesized and then linked with two liver-targeting ligands. The galactosylated human serum albumin coupled poly-L-lysine and the galactosylated poly-L-lysine. The effect of different modifications of ASONs on the expression of HBV gene was compared by using the 2.2. 15 cells. In the same experimental conditions, the inhibitary effects of surface antigen (HBsAg) and antigen (HBeAg) by PS-ASON were 70% and 58% respectively, and those of HBsAg and HBeAg by ligand-PS-ASONs were 90%-96% and 78%-82%. In the same time, the amount of HBV NDA in culture supernatant and cells was depressed significantly. Thus, the ligands targeted ASON to the hepatocytes were more effective inhibitors of HBV gene expression. ASONs were effective and specific inhibitors of HBV replication and expression, caused the dose-dependent inhibition of viral proteins and had no effect on cellular alpha-fetoprotein synthesis and no cytotoxicity.

Base Sequence↗
PubMed1995

[Pathological findings of proximal tubal occlusive infertility].

Exicised tubal segments (including interstial and isthmic portions) from 33 women with proximal tubal occlusive infertility were examined pathologically. We found that pathologic entities included chronic tubal inflammation (70.59%), tubal endometriosis (9.80%), obliterative fibrosis (7.84%), salpingitis isthmica nodosa (5.88%), tubal tuberculosis (3.92%). Only one of the tubes (1.96%) showed no obvious pathological change. These observations on proximal tubal occlusion in combination with clinical features and pelvic changes indicate that: (1) These are multiple distinct pathologic patterns, and pelvic findings do not predict the pathologic changes of the tubes. (2) Induced abortion and uterine curetage is an important factor for the proximal tubal occlusive infertility. Pelvic inflammatory disease and intrauterine device are other factors.

Abortion, Induced↗
PubMed1995

Immunoregulatory effects of the herba Epimediia glycoside icariin.

The in vitro effects of the Chinese Herba Epimediia glycoside icariine (ICA), a chinese herbal extract, on human immune responses were investigated. ICA induced a weak and delayed proliferation of peripheral blood mononuclear cells from healthy donors when compared to phytohemagglutinin. Both T- (TCR alpha beta+) and B cells were the ICA-responding cells. Within T-cells, the relative proportion of CD4-8+ cells increased but that of CD4+8- cells decreased. ICA in certain concentrations could increase lymphokine-activated killer cell (LAK) activity (0.1 to 1.0 microgram/ml) in both tumor patients and healthy donors, and natural killer cell (NK) activity (1.0 to 5.0 micrograms/ml) in tumor patients. Moreover, ICA stimulated the production of tumor necrosis factor-alpha in monocytes from healthy donors. These findings provide evidence that ICA could be applied to adoptive immunotherapy. Generation of LAK cells in presence of an appropriate dose of ICA might be superior to interleukin-2 alone.

Adjuvants, Immunologic↗
PubMed1995

[Surgical treatment of chronic pancreatitis and evaluation of therapeutic efficiency].

Twenty-eight patients with chronic pancreatitis (CP) were treated surgically in our department from 1987 to 1994. According to imaging features of B-us, CT, ERCP and operative pancreatogram, CPs were classified into five imaging types: mass type (11 cases), mass with dilated bile duct type (8), diffusely swelling type (4), dilated bile and pancreatic duct type (3), dilated pancreatic duct type (2). The surgical procedure was determined by considering both of the imaging type and major symptoms. The patients with pancreatic mass were treated mainly with pancreatic resection, whereas the patients with dilated bile or/and pancreatic duct were treated with bile or/and pancreatic ductal drainage procedures. Sphincteroplasty, neurectomy, lithotomy and T tube drainage were combined with above mentioned procedures according to intraoperative findings. One patient died of acute cholangitis and hepatic failure, 19 patients were free of pain postoperatively. There was no obvious deterioration of pancreatic function. These data suggest that pathologic changes of CP can be shown by imaging techniques. On the basis of imaging features and major symptoms, choice of appropriate procedure or combination of various operations will improve therapeutic efficiency of CP.

Adult↗
PubMed1995

[The prognostic significance of lymph node metastasis in surgical resection of esophageal cancer].

The metastatic rate and degree of lymph node (LN) were evaluated and the relation between prognostic significance and LN metastasis (M) was analysed through a retrospective study of 474 patients undergoing resections of non-irradiated esophageal carcinoma. In patients with LNM, the LNM rate was 44.5%. A total of 5382 LNs were resected and examined pathologically. 690 of them were metastatic ones with a LNM degree of 12.8%. The 5-year survival rate of this series was 30.6% (145/474), and was 12.8% (27/211) in patients with LNM and 44.9% (118/263) in those without LNM. We concluded that surgery remains the first choice of treatment for carcinoma of esophagus, and that meticulous LN dissection is an important part of surgical oncology. This is especially true when the cancer process is reasonably localized. However, in more advanced cases of this disease, surgery alone is of limited value in eradicating all cancer compromized tissue, and therefore the routine practice of extensive LN dissection in such cases may not be rewarding.

Adult↗
PubMed1995

[The effect of intralipid on the membrane fluidity of lymphocytes from human blood].

We observed the effect of 10% intralipid on the membrane fluidity of lymphocytes by means of fluorescent polarization measurement. After in vitro incubation with intralipid in concentration 0, 10, 20mg/ml, the lymphocytes from healthy adult blood showed no changes in the membrane fluidity (P > 0.05). In vivo, the membrane fluidity of lymphocytes did not alter significantly during and after infusion of 500ml 10% intralipid at a speed of 100ml per hour into healthy adult (P > 0.05). The level of blood triglyceride was elevated significantly during the infusion (P < 0.01), but decreased rapidly after the infusion. With 500ml per day of infusion (contral group), the surgical patients showed significant decrease in membrane fluidity of lymphocytes after operation (P < 0.01). But there was no significant difference between the study group and control group. The membrane fluidity might be affected by many factors. One of them is membrane lipid. Intralipid mainly contains triglycerides composed of polysaturated fatty acids and lecithin as emulsifier. The result showed that intralipid may neither alter the lipid composition of lymphocytes membrane nor the membrane fluidity. Furthermore, in case of modulation of membrane lipid composition by intralipid occurs, cellular self-regulation may be accomplished by fatty acid synthesis to keep the membrane fluidity stable.

Adult↗