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Biomedical subjects

Z Zhu

Publications and source records attributed to Z Zhu.

At least 343 records · Page 19Linked to original sources
PubMed1996

High level secretion of a humanized bispecific diabody from Escherichia coli.

Clinical development of bispecific antibodies (BsAb) has been effectively stymied by the lack of efficient production methods. We therefore attempted to produce a humanized BsAb fragment using an expression system that has proved very successful for secretion of monospecific Ab fragments from E. coli. An anti-p185HER2/anti-CD3 BsF(ab')2 was first recast into the diabody format and then periplasmically secreted from E. coli grown to high cell density in a fermentor. The diabody was recovered in very high yield (up to 935 mg/l) after protein A purification and predominantly (> or = 80%) as a dimer as judged by size exclusion chromatography. Diabody dimers were found to be mainly functional heterodimers (approximately 75%) by titration with p185HER2 extracellular domain. The diabody binds p185HER2 extracellular domain and human T lymphocytes with affinities close to those of the parent BsF(ab')2. Furthermore, the diabody is capable of simultaneous binding to tumor cells overexpressing p185HER2 and CD3 on T cells as shown by cellular rosetting. The diabody is equally potent as the parent BsF(ab')2 in retargeting IL-2 activated T-enriched peripheral blood lymphocytes to lyse tumor cells overexpressing p185HER2.

Amino Acid Sequence↗
PubMed1996

Low concentrations of ouabain increase cytosolic free calcium concentration in rat vascular smooth muscle cells.

1. Low ouabain concentrations in the nanomolar range significantly increased cytosolic free calcium concentration. 2. The ouabain-induced cytosolic free calcium concentration increase was due to transplasmamembrane calcium influx, which could be prevented in the absence of extracellular calcium or by addition of the calcium channel blocker nifedipine. 3. The amount of stored cellular Ca2+, as determined by the thapsigargin-induced cytosolic free calcium concentration increase, was also enhanced by 1 nmol/l ouabain. 4. It is concluded that low ouabain concentrations affect intracellular cytosolic free calcium concentration homoeostasis.

Animals↗
PubMed1996

Establishment of monoclonal antibodies against human erythrocyte NADH-cytochrome b5 reductase.

NADH-cytochrome b5 reductase (b5R) is a multifunctional redox enzyme, whose deficiency leads to hereditary methemoglobinemia. By using recombinant human red cell b5R as antigen to immunize BALB/c mice and conventional cell fusion, we have established two mouse hybridoma cell lines secreting IgG monoclonal antibodies (MAbs) to b5R. In immunoblotting, the MAbs were shown to react specifically with b5R. They were also found to be capable of capturing b5R activity from b5R solution and normal human hemolysate. It was implied that the binding sites of the MAbs might not be proximal to the active site of the enzyme, but might be in close proximity to each other. The MAbs will be useful in b5R-related investigations.

Antibodies, Monoclonal↗
PubMed1996

Skin cancer prevention and detection practices in a Michigan farm population following an educational intervention.

Farmers face an increased risk of skin cancer, presumed to be secondary to their increased occupational exposure to sunlight. This study examines skin cancer prevention and detection beliefs and practices among adult farmers in defined control and comparison farming communities in four contiguous counties of Michigan, before and after a community-based educational intervention. The educational intervention included mailing packets containing information on skin cancer risks and community sources for screening, disseminating articles in local newspapers on skin cancer prevention and control measures, and providing information and screening at local county fairs and agricultural community fairs. The responses of 2,999 survey participants were analyzed to identify the interrelationships among their beliefs and their descriptions of their (primary preventive) self-care and professional medical care seeking (for detection and treatment) practices. Factors associated with the likelihood of skin cancer screening and with measures of knowledge and practices associated with medical care of skin cancer were examined. The intervention appeared to improve the practice of preventive behaviors and seeking medical care.

Agriculture↗
PubMed1996

Dot-immunogold filtration assay as a screening test for syphilis.

A dot-immunogold filtration assay (DIGFA) for the rapid detection of reaginic antibody in the serum of syphilitic patients was developed. The assay was simple, rapid, and reproducible. The test completion time was 2 min, and the assay required no equipment. The positive dot was very obvious, and the results could easily be determined with the naked eye. A total of 350 serum samples were examined by DIGFA, the rapid plasma reagin test, and the fluorescent treponemal antibody-absorption test. The levels of agreement between DIGFA and the rapid reagin test and between DIGFA and the fluorescent treponemal antibody-absorption test were 100 and 98%, respectively. The results of clinical application indicated that DIGFA could be used as a routine screening test for syphilis.

Antibodies, Bacterial↗
PubMed1996

Targeting of glycoprotein I (gE) of varicella-zoster virus to the trans-Golgi network by an AYRV sequence and an acidic amino acid-rich patch in the cytosolic domain of the molecule.

Previous studies suggested that varicella-zoster virus (VZV) envelope glycoproteins (gps) are selectively transported to the trans-Golgi network (TGN) and that the cytosolic domain of gpI (gE) targets it to the TGN. To identify targeting signals in the gpI cytosolic domain, intracellular protein trafficking was studied in transfected cells expressing chimeric proteins in which a full-length or mutated gpI cytosolic domain was fused to the gpI transmembrane domain and interleukin-2 receptor (tac) ectodomain. Expressed protein was visualized with antibodies to tac. A targeting sequence (AYRV) and a second, acidic amino acid-rich region of the gpI cytosolic domain (putative signal patch) were each sufficient to cause expressed protein to colocalize with TGN markers. This targeting was lost when the tyrosine of the AYRV sequence was replaced with glycine or lysine, when arginine was replaced with glutamic acid, or when valine was substituted with lysine. In contrast, tyrosine could be replaced by phenylalanine and valine could be substituted with leucine. Mutation of alanine to aspartic acid or deletion of alanine abolished TGN targeting. Exposure of transfected cells to antibodies to the tac ectodomain revealed that the TCN targeting of expressed tac-gpI chimeric proteins occurred as a result of selective retrieval from the plasmalemma. These data suggest that the AYRV sequence and a second signaling patch in the cytosolic domain of gpI are responsible for its targeting to the TGN. The observations also support the hypothesis that the TGN plays a critical role in the envelopment of VZV.

Amino Acid Sequence↗
PubMed1996

Overexpression of the herpes simplex virus type 1 immediate-early regulatory protein, ICP27, is responsible for the aberrant localization of ICP0 and mutant forms of ICP4 in ICP4 mutant virus-infected cells.

ICP0 and ICP4 are immediate-early regulatory proteins of herpes simplex virus type 1. Previous studies by Knipe and Smith demonstrated that these two proteins are characteristically observed in the nuclei of wild-type virus-infected cells but predominantly in the cytoplasms of cells infected with several ICP4 temperature-sensitive (ts) mutant viruses at the nonpermissive temperature (NPT) (D. M. Knipe and J. L. Smith, Mol. Cell. Biol. 6:2371-2381, 1986). Consistent with this observation, it has been shown previously that ICP0 is present predominantly in the cytoplasms of cells infected with an ICP4 null mutant virus (n12) at high multiplicities of infection and that the level of ICP27, a third viral regulatory protein, plays an important role in determining the intracellular localization of ICP0 (Z. Zhu, W. Cai, and P. A. Schaffer, J. Virol. 68:3027-3040, 1994). To address whether the cytoplasmic localization of ICP0 is a common feature of cells infected with all ICP4 mutant viruses or whether mutant ICP4 polypeptides, together with ICP27, determine the intracellular localization of ICP0, we used double-staining immunofluorescence tests to examine the intracellular staining patterns of ICP0 and ICP4 in cells infected with an extensive series of ICP4 mutant viruses. In these tests, compared with the localization pattern of ICP0 in wild-type virus-infected cells, more ICP0 was detected in the cytoplasms of cells infected with all ICP4 mutants tested at high multiplicities of infection. Each of the mutant forms of ICP4 exhibiting predominantly cytoplasmic staining contains both the nuclear localization signal and the previously mapped ICP27-responsive region (Z. Zhu and P. A. Schaffer, J. Virol. 69:49-59, 1995). No correlation between the intracellular staining patterns of ICP0 and mutant forms of ICP4 was demonstrated, suggesting that mutant ICP4 polypeptides per se are not responsible for retention of ICP0 in the cytoplasm. This observation was confirmed in studies of cells cotransfected with plasmids expressing ICP0 and mutant forms of ICP4, in which the staining pattern of ICP0 was not changed in the presence of mutant ICP4 proteins. Studies of cells infected at low multiplicities with a variety of ICP4 ts mutant viruses at the NPT showed that both ICP0 and ts forms of ICP4 were localized predominantly within the nucleus. These observations are a further indication that the aberrant localization of the ts forms of ICP4 at the NPT is not a direct result of specific mutations in the ICP4 gene. In the final series of tests, the localization of ICP0 in cells infected with a double-mutant virus unable to express either ICP4 or ICP27 was examined. In these tests, ICP0 was detected exclusively in the nuclei of Vero cells but in both the nuclei and the cytoplasms of ICP27-expressing cells infected with the double mutant. These results demonstrate that ICP27, rather than the absence of functional ICP4, is responsible for the cytoplasmic localization of ICP0 in ICP4 mutant virus-infected cells. Taken together, these findings demonstrate that the aberrant localization of ICP0 and certain mutant forms of ICP4 in cells infected with ICP4 mutant viruses is mediated by high levels of ICP27 resulting from the inability of mutant forms of ICP4 to repress the expression of ICP27.

Animals↗
PubMed1996

Oxygen modulates alpha 1B-adrenergic receptor gene expression by arterial but not venous vascular smooth muscle.

Blood and tissue O2 levels are major determinants of short-term autoregulatory adjustments in vascular smooth muscle cell (SMC) tension and may effect long-term alterations in SMC catecholamine responsiveness. We examined the hypothesis that prolonged hypoxia altered gene expression of alpha 1-adrenoceptors. After exposure of cultured aortic (in vitro) SMC to 3% O2 for 8 h, alpha 1B mRNA increased to 523% (P = 0.02) of control cells (21% O2) and to 205% (P = 0.04) in in situ organ-cultured aortic SMC. In vivo hypoxic hypoxia (10% inspired O2) similarly increased aortic SMC alpha 1B mRNA 180% (P = 0.02). In contrast, alpha 1D, alpha-actin and beta-actin mRNA levels were not changed in aortic SMC by low O2 in the in vitro, in situ, or in vivo models. Unlike aortic SMC, vena caval SMC alpha 1B mRNA expression did not change with low-O2 exposure in vitro or in vivo, nor did alpha 1D, alpha-actin or beta-actin mRNA. Aortic SMC alpha 1B transcription rate increased 360% (P = 0.02), whereas alpha 1D, alpha-actin, and beta-actin transcription was unchanged. Neither alpha 1B nor alpha 1D mRNA stability was altered by low-O2 exposure. Total alpha 1-adrenoceptor density ([3H]prazosin binding) increased 12% (P = 0.04) after 24 h of 3% O2. This was associated with a 200% increase (P < 0.01) in the chloroethylclonidine (CEC)-sensitive alpha 1-adrenoceptor population and no change in CEC-insensitive alpha 1-adrenoceptor density. Exposure of aortic SMC to 24 h of 3% O2 increased the maximum response of norepinephrine-evoked elevations in intracellular Ca2+ as measured using fura 2. Low O2 did not change responses to another G protein-coupled receptor, angiotensin II. These data suggest that reduced O2, during prolonged hypoxemia or tissue ischemia, may selectively increase expression of functionally coupled alpha 1B-adrenoceptors in arterial blood vessels.

Actins↗
PubMed1996

Angiotensin II-receptor stimulation of cytosolic calcium concentration in cultured renal resistance arterioles.

This study provides an initial characterization of basic morphological properties of cultures of vascular smooth muscle cells (VSMC) from rat preglomerular resistance vessels and of the functional coupling of angiotensin II (ANG II) receptors to cytosolic free calcium concentration ([Ca2+]i (fura 2 fluorescence photometry). Renal VSMC were isolated from interlobular arteries and afferent arterioles (< 50 microns) using an iron oxide sieving method and compared with rat aortic VSMC cultured under similar conditions. Quiescent monolayers maintained uniform morphology and [Ca2+]i signaling profile between passages 3 and 10. Arteriolar and aortic VSMC were spindle shaped and expressed smooth muscle-specific alpha-actin and myosin heavy chains SM-1 and SM-2. ANG II caused a rapid increase in [Ca2+]i, followed by a sustained plateau phase at 50-60% of the peak value. The initial maximum [Ca2+]i responses were dose dependent and of similar magnitude in renal arteriolar and aortic VSMC. ANG II (10(-7) M) increased [Ca2+]i from 50 to 240 nM in arteriolar and from 57 to 201 nM in aortic VSMC (P < 0.001 for both). Inhibition of ANG II effects on [Ca2+]i revealed significant signaling through distinct AT-receptor subtypes (losartan and PD-123319 sensitive) in renal arteriolar VSMC. In contrast, only losartan was effective in aortic VSMC. The AT2-receptor ligand CGP-42112 had no effect in either vessel type. Our results demonstrate that cultured arteriolar VSMC have anatomical similarities to aortic VSMC and functional differences in AT-receptor signaling in response to ANG II. This novel preparation should provide a useful approach with which to investigate cellular mechanisms concerning receptor coupling to signaling pathways involved in vascular reactivity of arteriolar VSMC in the microcirculation in general and the kidney in particular.

Animals↗
PubMed1996

Evidence for a regulatory role for histamine in gastric enterochromaffin-like cell proliferation induced by hypergastrinemia.

BACKGROUND/AIMS: Hypergastrinemia, induced by sustained suppression of gastric acid secretion, is associated with gastric enterochromaffin-like (ECL) cell hyperplasia and carcinoid tumor formation. We examined the effect of a selective H1-histamine antagonist, terfenadine, on gastric mucosal cell proliferation to determine whether histamine might modulate ECL cell generation. METHODS: The rodent mastomys received the H2-antagonist loxtidine (2 g/l drinking water) alone or in combination with terfenadine (0.5 g/l or 35 mg/l drinking water) for 120 days. Controls received water or terfenadine alone. Serum gastrin levels and tissue histamine content were assayed by radioimmunoassays, and tissue chromogranin levels determined (Western blot analysis). In vivo cell proliferation was measured by bromodeoxyuridine (BrdU, 200 mg/kg/day, 3 days) incorporation. Gastric mucosal thickness was determined, ECL cell number was assessed, and the percentage of proliferating ECL cells quantitated. To evaluate the direct action on ECL cells we then studied the effect of terfenadine on histamine secretion and DNA synthesis (BrdU uptake) in an isolated preparation (approximately 90% pure) of ECL cells. RESULTS: Loxtidine increased serum gastrin levels, mucosal thickness, tissue chromogranin levels, tissue histamine content, BrdU incorporation, ECL cell number, and proliferating ECL cells (all parameters p < 0.05). Terfenadine alone, irrespective of dosage, had no significant effect. The high dose in combination with loxtidine significantly inhibited the increase in tissue chromogranin levels, tissue histamine content, ECL cell number and proliferating ECL cells (p < 0.05), but did not alter other parameters, compared to loxtidine alone. The low does did not alter the loxtidine-induced changes. In pure isolated ECL cells, terfenadine did not alter histamine secretion either alone or in combination with gastrin (10 nM). DNA synthesis was significantly inhibited by terfenadine (IC50 10(-10) M). CONCLUSIONS: Terfenadine specifically inhibited the effect of loxtidine-induced ECL cell proliferation in vivo and significantly inhibited ECL cell DNA synthesis in vitro. We postulate that histamine, through an H1 receptor, positively modulates gastric ECL cell proliferation.

Animals↗
PubMed1996

The design and preliminary evaluation of a home electrocardiography and blood pressure monitoring network.

A home electrocardiography (ECG) and blood pressure (BP) monitoring network was established in Beijing. The network consisted of three parts: (1) the home ECG and BP monitoring devices; (2) the monitoring centre at the hospital; and (3) the data communication network, for which we chose the public telephone network. The system was tested in our university hospital for two months with 30 patients and six normal volunteers. A preliminary evaluation by the users indicated that the system was acceptable in terms of its efficiency and effectiveness. This paper describes the system design, the preliminary testing procedure, and results.

Adult↗
PubMed1996

[Immune and biochemical analysis of protein of homogenates of three different kinds of skin].

The amount and constitution of protein, its ultraviolet photo-absorption ability, and esterase in homogenates of human cadaveric and guinea pig skin (each consisted of newborn, fresh adult and stored adult skin) were assayed by using ultraviolet spectrophotometer, polyacrylamide gel electrophoresis and sodium dodecyl sulphate polyacrylamide gel electrophoresis. Our experiment shows that immune and biochemical analysis of protein of three different skin groups are different. The biochemical components of cadaveric and guinea pig skin protein and esterase in newborn skin group are lowest. The changes in adult skin stored at -196 degrees C are less obvious as compared with that in fresh adult skin.

Animals↗
PubMed1996

Platelet activating factor inhibits fluid transport by corneal endothelium.

PURPOSE: Given reports of corneal edema after endothelial exposure to platelet activating factor (PAF), the authors have investigated whether PAF can affect the function of corneal endothelium in vitro. METHODS: The endothelial side of deepithelialized rabbit corneas was perfused with BSS+ and test agents: PAF, its inactive receptor ligand analog Lyso-PAF, and its antagonist BN52021. Stromal thickness was determined by specular microscopy. Translayer-specific electrical resistance (rho) was measured in cultured bovine corneal endothelial cells grown on permeable substrates at 36.5 degrees C. RESULTS: Control corneas perfused with BSS+ or with BSS+ containing Lyso-PAF swelled at a very slow rate (6.2 +/- 0.1, and 7.9 +/- 0.2 microns/hour, respectively). Corneas exposed to PAF swelled appreciably faster and at rates that were a saturable function of PAF (K(m), 2.1 microM); maximal rates of swelling were < 20 microns/hour, indicating no appreciable damage to intercellular junctions. BN52021 prevented PAF-induced swelling (Ki, 1.1 microM). PAF led also to a decrease in rho (from 42.8 +/- 1.4 to 24.5 +/- 0.6 omega cm2 in 1 hour; 46.8 +/- 1.5 to 38.3 +/- 1.4 omega cm2 in control layers; and 43.0 +/- 1.2 to 30.8 +/- 1.6 omega cm2 in layers exposed to PAF+BN52021). Such rho changes are consistent with swelling of intercellular spaces. CONCLUSIONS: Results suggest that PAF inhibits transendothelial fluid transport on binding to an endothelial cell receptor for it; continuous stimulation of a PAF-induced signaling cascade may lead to such inhibition. From these and other results, fluid transport might result from cascades activating sequentially basolateral and apical transporters or channels.

Animals↗
PubMed1996

High level expression of oryzacystatin in Escherichia coli.

A rice cDNA library of immature seeds has already been constructed, from which colonies carrying oryzacystatin cDNA were isolated. The coding region of the oryzacystatin (a thiol proteinase inhibitor) gene was amplified by the Polymerase Chain Reaction (PCR) and inserted downstream of lambdaPRPL promoter of E. coli thermal-inducible expression vector pBV220. An oryzacystatin expression plasmid pBVC9 was therefore obtained. Shifting the culture temperature of E. coli DH5 alpha (pBVC9) from 30 degrees C to 42 degrees C led to a high level expression of oryzacystatin. The result of SDS-PAGE showed a distinct band of 12.0 kDa which accounts for at least 10% of the total soluble proteins. The inhibitory activity of the total soluble proteins of E. coli DH5 alpha (pBVC9) toward papain was confirmed by using that of E. coli DH5 alpha (pBV220) as a control.

Cloning, Molecular↗
PubMed1996

An epidemiological survey on use and abuse of antianxiety drugs among Beijing residents.

OBJECTIVE: To investigate the current trend of use and abuse of antianxiety drugs in Beijing residents in 4 urban and 2 rural areas. METHODS: A cluster sampling household survey of 6567 subjects out of 3000 families was made by 6 local grass roots mental health centers collaboratively. Screened with designed questionnaire, the positive addicted subjects were examined with present state examination (PSE), eysenck personality questionnaire (EPQ) and social disability screening schedule (SDSS) to detect their psychosocial status. RESULTS: Benzodiazepine (BZD) has been widely prescribed and the rate of usage for 1 year is 61.82/1000, whereas the rate of dependence is 16.29/1000, constituting 1/4 of long-term users. This study also indicates that Valium is a most preferred drug among all available BZD used by the majority of addicted subjects. CONCLUSIONS: It is concluded that the reported dependence is not epidemic but iatrogenic in nature attributable to persistent misuse of BZD. It is stressed that guideline of rational clinical application of BZD should be laid down so as to markedly reduce further possible misuse and abuse of the drugs of this kind.

Adolescent↗
PubMed1996

[Measurement of blood NO contents using ESR method in rats after thermal injury].

The contents of nitric oxide (NO) in the blood were measured by electron spin resonance (ESR) method in Wistar rats with 35% TBSA III degrees burn. NO is endothelium derived relaxing factor (E-DRF) released by vascular endothelial cells. The results showed that: 1. Blood NO contents were not found to be significantly increased (72 hours postburn); 2. Escherichia coli lipopolysaccharide (LPS, endotoxin) could induce excessive NO formation in early burns.

Animals↗
PubMed1996

[The changes in TNF alpha in plasma, organs and eschar of rats after thermal injury].

The TNF alpha (Tumor Necrosis Factor-alpha) contents in the plasma, five organs (heart, lung, liver, kidney and intestine) and burned skin were measured by ELISA method in Wistar rats with 35% TBSA III degrees. The animals were divided into eight different time groups. The experiment showed that TNF alpha contents were excessively high in early stage of burn (24 hours postburn) in plasma, eschar and the five organs. The contents of TNF alpha in eschar were 27.5-86.7 times higher than that in plasma and the five organs.

Animals↗