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Biomedical subjects

J Z Wang

Publications and source records attributed to J Z Wang.

At least 19 recordsLinked to original sources
PubMed1995

Dephosphorylation of Alzheimer paired helical filaments by protein phosphatase-2A and -2B.

Microtubule-associated protein tau is abnormally hyperphosphorylated in the brain of patients with Alzheimer disease and in this form is the major protein subunit of the paired helical filaments (PHF), the most prominent lesion of the disease. In this study the dephosphorylation of sparingly soluble PHF, PHF II-tau by brain protein phosphatase (PP)-2A1 and PP-2B, and the resulting biochemical, biological, and structural alterations were investigated. Both of the phosphatases dephosphorylated PHF II-tau at the sites of Ser-199/Ser-202 and partially dephosphorylated it at Ser-396/Ser-404; in addition, PHF II-tau was dephosphorylated at Ser-46 by PP-2A1 and Ser-235 by PP-2B. The relative electrophoretic mobility of PHF II-tau increased after dephosphorylation by either enzyme. Divalent cations, manganese, and magnesium increased the activities of PP-2A1 and PP-2B toward PHF II-tau. Dephosphorylation both by PP-2B and PP-2A1 decreased the resistance of PHF II-tau to proteolysis by the brain calcium-activated neutral proteases (CANP). The ability of PHF II-tau to promote the in vitro microtubule assembly was restored after dephosphorylation by PP-2A1 and PP-2B. Microtubules assembled by the dephosphorylated PHF II-tau were structurally identical to those assembled by bovine tau used as a control. The dephosphorylation both by PP-2A1 and PP-2B caused dissociation of the tangles and the PHF; some of the PHF dissociated into straight protofilaments/subfilaments. Approximately 25% of the total tau was released from PHF on dephosphorylation by PP-2A1. These observations demonstrate that PHF II-tau is accessible to dephosphorylation by PP-2A1 and PP-2B, and dephosphorylation makes PHF dissociate, accessible to proteolysis by CANP, and biologically active in promoting the assembly of tubulin into microtubules.

Alzheimer Disease↗
PubMed1995

Kinetic images of neuronal activity of the human brain based on the spatio-temporal MNLS inverse: a theoretical study.

Prior work proved that it is possible to find a unique solution to the problem of defining the configuration of electric current underlying observed extracranial magnetic fields, if sufficient priori knowledge of the source configuration is available. This minimum-norm least-squares (MNLS) inverse solution for a magnetic source image (MSI) is extended here to include temporal as well as spatial parameters of the underlying current pattern. This capitalizes on the temporal resolution of magnetoencephalography (MEG), which is on the order of milliseconds. Other forms of functional brain imaging are far less sensitive to the rate of change of states of the brain. Influences on the quality of the resulting MSI by measurement noise and errors in determining the image surface are characterized. A new technique for reducing noise in the inverse problem is developed by taking into consideration the spatial and time-dependence of the noise detected by the sensors. This new approach to regularization reduces the contribution from noisy measurements to the inverse calculation, and therefore improves the stability of the inverse.

Brain Mapping↗
PubMed1995

Phosphatase activity toward abnormally phosphorylated tau: decrease in Alzheimer disease brain.

Microtubule-associated protein tau is abnormally hyperphosphorylated and aggregated in affected neurons of Alzheimer disease brain. This hyperphosphorylated tau can be dephosphorylated at some of the abnormal phosphorylated sites by purified protein phosphatase-1, 2A, and 2B in vitro. In the present study, we have developed an assay to measure protein phosphatase activity toward tau-1 sites (Ser199/Ser202) using the hyperphosphorylated tau isolated from Alzheimer disease brain as substrate. Using this assay, we have identified that in normal brain, protein phosphatase-2A and 2B and, to a lesser extent, 1 are involved in the dephosphorylation of tau. The Km values of dephosphorylation of the hyperphosphorylated tau by protein phosphatase-2A and 2B are similar. The tau phosphatase activity is decreased by approximately 30% in brain of Alzheimer disease patients compared with those of age-matched controls. These findings suggest that a defect of protein phosphatase could be the cause of the abnormal hyperphosphorylation of tau in Alzheimer disease.

Aged↗
PubMed1995

The effects of an algal polysaccharide from Gloiopeltis tenax on transplantable tumors and immune activities in mice.

Funoran (an algal polysaccharide from Gloiopeltis tenax) significantly inhibited the growth of Ehrlich ascites carcinoma and solid Ehrlich, Meth-A fibrosarcoma, and Sarcoma-180 tumors. In tumor-bearing mice, funoran significantly induced the enhancement of delayed-type hypersensitivity response to sheep red blood cells. When given intraperitoneally, funoran increased the spleen weight of mice. Morphological observations indicated that funoran augmented the transformation from lymphocytes to plasma cells in the spleen. In addition, changes in the T-cell subsets in the spleen, thymus, and peripheral blood were measured by flow cytometry. The results showed that the percentages of L3T4+ and Lyt 2+ T-cells were markedly increased in the peripheral blood. The percentages of asialo CM1+ cells in the thymus and peripheral blood were also significantly increased. Our results suggest that the antitumor effect of funoran is related to the augmentation of T-helper, T-cytotoxic, and NK cells.

Adjuvants, Immunologic↗
PubMed1994

MNLS inverse discriminates between neuronal activity on opposite walls of a simulated sulcus of the brain.

The minimum-norm least-squares inverse for magnetic field measurements is applied to a representation of a sulcus of the human brain, where one or both walls have regions of neuronal activity. Simulations indicate that the magnetic source image (MSI) is largely confined to the appropriate wall of the sulcus, even for a depth of 4 cm where the distance between walls is only 3 mm. Two nearly oppositely oriented dipoles located 3 mm apart are found to be distinguished. Influences on the quality of the MSI by measurement noise and inaccuracy in determining the image surface are discussed in detail.

Brain↗
PubMed1994

[Iatrogenic osteoporsis: six case reports].

Iatrogenic osteoporosis is a very common secondary osteoporosis is found in patients treated with large dosage of glucocorticosteroid of long duration. Six cases listed in this article including 2 cases of bronchial asthma, 2 cases of bronchial asthma, 2 cases of rheumatoid arthritis, 1 case of skin disease and 1 case of callagenosis (three male patients and three female patients). The age is from 27-46. The duration of treatment of primary disease with glucocorticosteroid is 1 to 3.5 years, with the average of 1.56 years. With the exception of one case treated with Dexamethasone one of 0.75g daily, the other 5 cases are treated with predinisone of 5-30mg daily. After they treated with hormone every other day and added Calcium and vitamin D and followed up 1 year, the mineral contents in the bone of all 6 patients are increased and the biochemistry indexes are improved.

Adult↗
PubMed1994

[Analytical study on processing of Rheum palmatum L. by HPLC].

This paper deals with the effect of processing on Rheum palmatum. A HPLC method for the determination of rhein in the drug processed five different ways has been established. The method is simple, specific and accurate. The recovery is 98.52% and relative standard deviation.

Anthraquinones↗
PubMed1994

[Effects of chloroform, chlorobenzene and polychlorinated biphenyls on erythrocyte lipid peroxidation and membrane fluidity in poisoned rabbits].

Effects of three chlorinated compounds, i.e., chloroform, chlorobenzene and Aroclor 1254 (PCBs), on lipid peroxidation and membrane fluidity of erythrocytes in poisoned rabbits were studied. Results revealed daily intraperitoneal injection of peanut oil containing chlorinated compounds into rabbits showed nonenzymic promotion effects on its erythrocyte lipid peroxidation in varying degrees, but different effects on erythrocyte membrane fluidity, promoting by chloroform and inhibiting by Aroclor 1254. It suggested the constitutional characteristics of toxicant molecules also had effects on membrane fluidity. In addition, it was found there existed potential relationship between maintenance of cell morphology and membrane fluidity.

Animals↗
PubMed1994

An investigation of pedigrees of 110 patients with Graves' disease and the clinical significance of determinations of antithyroid antibodies of their first-degree relatives.

Eight hundred and ten pedigree members of 110 patients with Graves' disease were studied. In 700 first-degree relatives, inquiry of medical history, physical examination (including eyes, thyroid, heart rate, etc), thyroid function tests (serum T3, T4 and TSH levels), determinations of thyroglobulin antibodies (TgAb) and thyroid microsomal antibodies (TmAb) were performed. For male (female) probands, the incidence of Graves' disease in male (female) first-degree relatives were investigated and their serum TgAb and TmAb were analysed. The incidence of these two kinds of autoantibodies in the male (female) first-degree relatives of familial and nonfamilial Graves' disease were analysed. Eighteen persons with positive TgAb and TmAb from 5 pedigrees had been followed up one year after initial determinations. Our results suggest that the positive rates of TgAb and TmAb in the first-degree relatives of Graves' disease were coincident with the incidence of Graves' disease, and the positive results of TgAb and TmAb in the first-degree relatives of Graves' disease may be an indicator of pre-Graves' disease or pre-autoimmune thyroid diseases.

Autoantibodies↗
PubMed1994

[Analytical study on processing of Scutellaria baicalensis Georyl by HPLC].

This paper deal with the effect of processing on Scutellaria baicalensis. A HPLC method for the determination of baicalin in the drug processed in four different ways has been established. The method is simple, specific and accurate. The recovery is 99.5% and relative standard deviation 0.99%.

Chromatography, High Pressure Liquid↗
PubMed1994

IL-1 induces intracisternal type A virus and retrovirus type C in pancreatic beta-cells of NOD mice.

Recent observations have suggested a role for interleukin 1 (IL-1), a macrophage-derived cytokine, in the autoimmune beta-cell destruction, that is associated with type 1 diabetes. In this study, we investigated the effects of human recombinant IL-1 beta on pancreatic beta-cells from NOD and NON mice (diabetes-resistant NOD-related strain), focussing upon the appearance of intracisternal type A virus (IAP) and retrovirus type C. NOD mice pancreatic islets were incubated with or without IL-1 (0.1, 1, 10, 100 U/ml) for 10 days. Thereafter, the islets were examined using an electron microscope. When the islets of NOD mice were incubated with the IL-1 (10, 100 U/ml) under condition of high glucose, IAP and endogenous retrovirus type C frequently appeared in the beta-cells. Retrovirus type C was present as a cluster. In contrast, IAP and retrovirus type C were rarely found in beta-cells from the control group. When the islets of NON mice were incubated with or without IL-1 (10 U/ml) in the presence of high glucose, IAP was rarely found in beta-cells and retrovirus type C was undetectable in beta-cells. This study indicated that IL-1 is an important effector that leads to insulitis or aggravates insulitis in NOD mice.

Animals↗
PubMed1994

[An experimental study on photosensitization of cultured human cells with hypocrellin A].

The photosensitive effects of hypocrellin A on cultured HeLa cells were studied by the methods of immunofluorescence cytochemistry, flow cytometry and others. The results showed that, in the presence of 3.66 mumol/L hypocrellin A, illumination of HeLa cells with visible light, the morphology was changed and the microvilli on the cells were disappeared; the proliferation of the cells decreased with increasing irradiated dose and this effect seemed more sensitive in tumor cells than in normal cells; the increased population of cycle cells at S phase but decreased at G1 phase were observed by FCM; the photodamage effect of hypocrellin A induced the sparse distribution of cytoplasmic microtubles and almost disappearance of the fluorescence intensity of MTOC, they were observed in HeLa cells as shown by immunofluoresent microscopy. All the aforesaid results indicated that photosensitization of hypocrellin A inhibits cells growth, resulting from the damage in cell membrane and cytoskeleton and S phase delay of the cell cycle.

Cell Division↗
PubMed1994

The character of endogenous retrovirus in pancreatic beta-cells of NOD mice.

The character of retrovirus type C in NOD mouse pancreatic-beta-cells was investigated. First, the in vitro response of retrovirus type C to glucose stimulation was examined. When the pancreatic islets of control NON mice were observed with an electron microscopy retrovirus types C could not be detected in the beta-cells with or without glucose stimulation. Retrovirus type C particles and intracisternal type A particles (IAPs) in NOD mouse pancreatic beta-cells increased by glucose stimulation, but the increase in retrovirus type C differed from that of IAPs. The clusters of retrovirus type C were found in some beta-cells, whereas IAPs were scattered in beta-cells. Next, we investigated the expression of retrovirus type C transcript in NOD mouse pancreatic islets. From polymerase chain reaction analysis using two primers of retrovirus type C designed from a conserved U3 region, a major product was found to be endogenous polytropic retrovirus (Pmv). The subcloned PCR probe and oligonucleotide probes specific for Pmv and modified polytropic retrovirus were used for Northern blot analysis. Pancreatic islets from NOD and NON mice (control mice) contained 8.4-kb and 3.0-kb Pmv transcripts. The quantity of transcripts of Pmv in NOD mouse pancreatic beta-cells were the same as that in NON mice. The transcript level of islets was much higher than those of thymus and liver. The appearance of retrovirus type C particles in beta-cells of NOD mice may involve the mechanisms by which diabetes is generated in NOD mice.

Animals↗
PubMed1993

Imaging regional changes in the spontaneous activity of the brain: an extension of the minimum-norm least-squares estimate.

This paper describes methods for inferring mathematically unique local distributions of primary cortical current that underly changes in the average pattern of power of the ongoing ("spontaneous") extracranial magnetic field of the brain. In previous work we demonstrated that mathematically unique solutions to the inverse problem are possible for current sources of the brain's field, without assuming a small set of current dipoles as a source model. In principle, it is possible to locate and delineate patterns of current of any configuration. In practice this approach applies to synchronized neuronal activity, e.g., activity which is known to underly average evoked or event-related brain responses. This paper extends that approach to local changes in incoherent activity, e.g., activity yielding fields or potentials that tend to be self-cancelling when averaged over time. This includes the spontaneous brain activity normally treated as background noise when it accompanies event-related responses. We demonstrate that local changes in this ongoing incoherent activity may also be uniquely delineated in space and time. The solution is a covariance matrix characterizing activity across an image surface. Its diagonal elements represent the spatial pattern of mean current power. Evidence is reviewed indicating that the distribution of the brain's magnetic field, due to both its synchronized and incoherent neural activity, is affected by early sensory-perceptual processes and by higher cognitive processes. Hence, in principle, the ability to delineate both kinds of sources in space and time makes it possible to form more comprehensive dynamic functional images of the human brain.

Brain↗
PubMed1993

[A comparative study on cholagogic effect of Artemisia].

The result suggests that the cholagogic effect of A. anethoides, A. haichowenesis and A. capillaris are not different significantly (P > 0.05), but the duration of action caused by anethoides and haichowenesis is longer than that caused capillaris. The cholagogic effect of A. capillaris collected in seedling, flower budding (beginning of autumn) and preflower periods were also investigated separately, and the preflower collection was found more cholagogic.

Animals↗
PubMed1992

Antitumor activity of polysaccharide from a Chinese medicinal herb, Acanthopanax giraldii Harms.

The results of experiments with Acanthopanax giraldii polysaccharide (AGP) demonstrated that it inhibited the growth of solid Sarcoma 180 and prolonged the survival time significantly. In tumor-bearing mice, AGP enhanced the phagocytosis and chemiluminescence of macrophages. By the immunofluorescent method, binding of the third component of complement (C3) cleavage product to macrophages and proportion of C3 positive cells were increased. In crossed immunoelectrophoresis, human serum C3 was converted by AGP and appeared as the 3rd peak. The height of the 3rd peak was directly proportional to doses of AGP. The residual CH50 units of human serum decreased dose-dependently. These results suggest that the antitumor activity of AGP is related to the enhancement of immune responses.

Animals↗