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Biomedical subjects

W Zhang

Publications and source records attributed to W Zhang.

At least 937 records · Page 52Linked to original sources
PubMed1997

The mitogenic effect of parathyroid hormone is associated with E2F-dependent activation of cyclin-dependent kinase 1 (cdc2) in osteoblast precursors.

Injections of parathyroid hormone (PTH) have been reported to stimulate skeletal accretion through increased bone formation in several species, and osteoblast proliferation is a critical component of bone formation. However, the biological mechanisms of PTH-stimulated bone cell proliferation are largely unknown. In this study, we demonstrated that PTH stimulates proliferation of the osteoblast precursor cell line, TE-85, in association with increasing cdc2 protein levels and its kinase activity. cdc2 antisense oligonucleotides blocked PTH-induced DNA synthesis and cell cycle progression. Analysis of the time course of PTH-stimulated cdc2 message levels demonstrated that cdc2 mRNA levels were increased 1.5- to 4-fold between 3-18 h following release from cell synchronization. Transfections of TE-85 cells with a series of cdc2 promoter-luciferase deletion constructs revealed PTH stimulation of the cdc2 promoter. Promoter constructs containing a mutation in the E2F binding site were not stimulated by PTH. Gel mobility shift assays demonstrated increased free E2F levels in TE-85 nuclear extracts in response to PTH. Furthermore, the ratios of hyperphosphorylated to hypophosphorylated forms of Rb protein were increased by PTH treatment. These results demonstrate that PTH-stimulated cdc2 expression was associated with TE-85 cell proliferation and that the mechanism of stimulating cdc2 gene expression involved increasing the levels of free E2F.

CDC2 Protein Kinase↗
PubMed1997

Development of pathological lesions in the central nervous system of transgenic mice expressing the env gene of ts1 Moloney murine leukemia virus in the absence of the viral gag and pol genes and viral replication.

The ts1 Moloney murine leukemia virus causes a degenerative neurologic disease in mice characterized by the development of noninflammatory spongiform encephalomyelopathy. To determine whether gag and pol gene products and viral replication are necessary for the ts1-env gene product to cause neurodegeneration, we generated transgenic mice harboring only ts1-env. Neuropathological lesions were observed in mice expressing the transgene in the central nervous system. This implies that gag and pol gene products and viral replication are not necessary for ts1-env to cause a mild form of neurodegeneration in mice.

Animals↗
PubMed1997

Kinetics of the thermal inactivation of alkaline phosphatase from green crab (Scylla serrata).

The kinetics of thermal inactivation of alkaline phosphatase from green crab (Scylla Serrata) has been studied using the kinetic method relating to the substrate reaction during irreversible inhibition of enzyme activity previously described by Tsou. The results show that the thermal inactivation of the enzyme is an irreversible reaction. Comparison of the microscopic rate constants for thermal inactivation of free enzyme and the enzyme-substrate complex shows that the presence of substrate has a certain protective effect against thermal inactivation.

Alkaline Phosphatase↗
PubMed1997

[Effects of acute repeated hypoxia on levels of adenosine and its A1 receptor in mouse brain].

Experiments were conducted on Kunming mice. Content of adenosine (ADO) and its metabolites in the brain was measured by specific enzymatic method, and radioligand binding method was used to study ADO A1, receptor. ADO content of the hippocampus in group C (hypoxia exposure for four runs) was markedly higher than that in groups A (control, without hypoxia exposure) and B (hypoxia exposure for one run), showing that ADO content can be cumulatively increased in the hippocampus, which is more sensitive to ischemia and hypoxia, during acute repeated hypoxia exposures. A1 receptor density, but of group C was significantly lower than that of group A and no difference was seen between groups B and C, but A1 receptor affinity in the hippocampus, pons and medula oblongata in group C was significantly higher than that in group A, implying that during acute repeated hypoxia there may be some mechanisms preventing A1 receptor density from decreasing further and making A1 receptor affinity increase in some brain regions. These results indicate that cumulatively increased ADO in the hippocampus via A1 receptor may play a neuroprotective role in CNS as an inhibitory neuromodulator and thus contribute to the formation and development of acute hypoxia adaptation or tolerance.

Adenosine↗
PubMed1997

[Brain dialysis--a new technique for determining the release of neurotransmitters and neuropeptides].

Brain dialysis, also called microdialysis, is a new technique based on the push-pull cannula. It can be used for continuously perfusing and collecting perfusate of certain brain areas in freely moving animals. Coupled with high performance liquid chromatography (HPLC) and radioimmunoassay (RIA), brain dialysis is allowed to determine the extracellular changes of many neurotransmitters in the brain, such as acetylcholine, noradrenaline, dopamine, 5-HT and their metabolites, free amino acids, small peptides, phosphoethanolamine, vitamins, various ions and so on.

Acetylcholine↗
PubMed1997

[A continuous and constant rate administration method--mini-osmotic pump].

Mini-osmotic pump is a delicate administration method. When it is activated by water, mini-osmotic pump can deliver a variety of solutions or suspensions at a constant rate for days even up to several weeks. Since it is drived by osmotic pressure, the pumping rate is independent on the physical and chemical feature of the drugs. The pump from inside to outside consists of a cylindrical reservior, osmotic driving agent and semipermeable membrane.

Animals↗
PubMed1997

[Effect of interleukins on proliferation of cultured rat anterior pituitary cells].

The present study investigated whether IL-1 and IL-6 involved in the control of proliferation in cultured anterior pituitary (AP) cells. Primary culture of AP cell were obtained from either male and female Sprague-Dawley rats. The effects of IL-1 and IL-6 assessed by [3H]-thymidine incorporation rate. It was found that: (1) IL-1(1-100 ng/ml) stimulated 3H-TdR incorporation into AP cells of male and female rats. (2) The lower concentration of IL-6 (0.1 ng/ml) inhibited 3H-TdR incorporation rate, but higher concentration of IL-6 (1-10 ng/ml) stimulated 3H-TdR incorporation into AP cells of male rats. (3) IL-6 (0.1-10 ng/ml) stimulated 3H-TdR incorporation into AP cells of female rats. These results indicated that IL-1 and IL-6 can modulate the endocrine activity as well as the proliferation of AP cells.

Animals↗
PubMed1997

[Determination of airway reactivity in the conscious and unrestrained guinea pigs].

A simple, stable determining system in the conscious and unrestrained guinea pigs was established that can quantitatively analyse the airway reactivity (AR). In this model, the response to histamine (His) or acetylcholine (ACh) aerosol was concentration-dependent with EC50 effective concentration causing 50% animals wheezing) of 53.3 mumol/m3 and 269 mumol/m3 respectively.

Acetylcholine↗
PubMed1997

[Bicuculline stimulates the release of adrenocorticotropin (ACTH) from rat anterior pituitary quarters].

The effect of gama-aminobutyric acid (GABA) on release of adrenocorticotropin (ACTH) from anterior pituitary quarters of male SD rats adrenalectomized for 96 hrs was investigated using the perfusion technique in vitro. Application of bicuculline (10(-6)mol/L), a specific GABA-A antagonist, resulted in a significant release of ACTH from perfused anterior pituitary quarters. But the same concentration of bicuculline had no effect on the release of ACTH from dispersed anterior cells of ADX rats in vitro. Taken together, these results suggest that GABA may play an important inhibitory role on ACTH secretion from pituitary in adrenalectomized rats.

Adrenalectomy↗
PubMed1997

[Spectrophotometric method for determination of protein in food with Hantzsch reaction].

A new spectrophotometric method for the determination of protein in food was developed. The method is based on the reaction of ammonia in Kjeldahl digest with acetylacetone for maldehyde reagent in pH4.8 acetate medium to yield a yellow compound 3,5-diacetyl-2,6-dimethyl-1,4-dihydropyridine. Beer's law is obeyed in the concentration range of 0-10.0 mg/L at 400 nm. The molar absorptivity in terms of nitrogen was 1.7 x 10(-3). The recoverites of the added standard samples were 99.6%-101.2%, and relative standard deviation was below 3.7%.

Dietary Proteins↗
PubMed1997

[Mast cells of ileocecal junction in irritable bowel syndrome].

To investigate whether the mast cells (MC) of the ileocecal junction (ICJ) is elevated in the irritable bowel syndrome (IBS) and the possible roles of the MC in IBS, the biopsies of ICJ were stained specifically by histochemistry for the MC in the IBS group (n = 20) and the normal group (n = 19). The structure relation between MC and nerves was studied through an electronic microscopy and an immunohistochemical method demonstrating neuronspecific enolase. The results demonstrated that the number of the MC of ICJ was significantly elevated in the IBS (P = 0.019) and that mast cells were close to nerves which were often unmyelinated nerves in lamina propria. The results indicate that the MC of ICJ may be responsible for the pathophysiology of the IBS. We conclude that the MC of ICJ may be a mediator between the gut and the nervous system in the IBS, and that the mast cell stabilizer or the antagonists of the mast cell products may have potential treatment effects on the IBS.

Adult↗
PubMed1997

[Relation of continuous ICP, CPP monitoring with prognosis for severe brain injury].

We analysed the treatment results of two groups of patients. Group I included 50 patients with severe brain injury with GCS 3-8, on whom continuous intracranial pressure (ICP) and cerebral perfusion pressure (CPP) monitoring was performed and Group II included 50 cases of similar patients, on whom no continuous ICP monitoring was performed. In Group I 8 patients had normal ICP (< 2.0 kPa), CPP (> 9.33 kpa), and the rest 42 had increased, ICP and reduced CPP. After adequate intervention including operation and drug treatment, group I patients had good results with a mortality of 14%. Group II patients received the same intervention based on clinical observations, but they had relatively worse results. We are of the opinion that continuous ICP and CPP monitoring for severe brain injury patients helps find proper treatments and reduce mortality.

Adolescent↗
PubMed1997

[The alveolar bone density in rats with experimental diabetes].

The alveolar bone turnover in rat with experimental diabetes was investigated. The serum osteocalcin concentration in diabetic rat was shown to increase as determined by radioimmunoassay; while alveolar and femur bone density decrease as determined by Dual Energy X-ray Bone Densitometer; histological examination showed that bone resorption was increased and bone formation decreased in the alveolar bone in diabetic rat. It is suggested that the alveolar bone in rats with diabetes mellitus have a tendency to develop osteoporosis.

Alveolar Process↗
PubMed1997

[A positioning device for oral paralleling technique].

OBJECTIVE: To design a reliable method for standardized paralelling dental projection, for comparison of the tiny variations of alveolar bone during the treatment of the periodontal disease. METHODS AND MATERIAL: Periapical radiographs in 29 pairs of films with this device and 14 pairs of films with traditional method on dried skulls were comparatively analysed by digital subtraction. Standard deviations and angle variations of subtracted image were studied comparatively between this method and traditional paralleling technique. RESULTS: Significant difference of reproducibility between two groups was showed. The reproducibility of the successive pictures was apparently increased when projected with positioning device.

Alveolar Process↗
PubMed1997

[A comparative study of lanthanum, cerium and fluoride on the prevention of root surface caries by various procedure].

In order to evaluate the anticaries effects of several trace elements by combined and respective treating procedure, studies on inhibiting demineralization and improving remineralization were carried out with lanthanum, cerium and fluoride in a pH-cycling condition. The analysis of polarized microscope and electron microprobe demonstrated that the lanthanum and fluoride to an acetate buffer solutions had less severe demineralization of root surface than individual lanthanum or fluoride to the solution. The former, furthermore, precipitated a compound membrane which may be F-La(Ce)-Ca containing crystal on the root surface, and showed a better resistibility to acid. A further discussion was made from the viewpoint of crystal physiochemistry.

Adolescent↗
PubMed1997

[The study of effects of immunologic modifier on proliferation and cytotoxicity against HEP-2 of LAK cells in vitro].

Adoptive immunotherapy as a new approach has been used to treat advanced carcinoma for almost ten years, and gained some good results. However, the application of this method is largely restricted by the side effects along with high dose of IL-2 and lack of sufficient amount of LAK cells. Mycobacterial Polysaccharides (MPS) and anti-CD3 antibodies (CD3Ab) have been demonstrated to be effective immunologic modifiers capable of proliferating lymphocytes and increasing cytotoxity against tumor cells. In this article we discussed the effects of MPS and CD3Ab on proliferation and cytotoxity against HEP-2 cells of LAK cells. Our results showed that: 1. MPS group (incubating IL-2 2 x 10(5)/L plus MPS 0.4 mg/L) or CD3 group (IL-2 1 x 10(6)/L plus CD3Ab 4 mg/L) were more proliferative than LAK group (only incubated with IL-2 1 x 10(6)/L). MPS group is the most proliferative in the three groups, P < 0.05. 2. Cytotoxity against HEP-2 in MPS or CD3 group was also better than in LAK group. CD3 group could maintain good cytotoxity in the longest period. These results could provide guidance for adoptive immunotherapy assisted by MPS or CD3Ab.

Antibodies, Monoclonal↗