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Biomedical subjects

J P Wang

Publications and source records attributed to J P Wang.

At least 19 recordsLinked to original sources
PubMed2000

Isolated hepatic cholinergic denervation impairs glucose and glycogen metabolism.

BACKGROUND: Hepatic innervation plays an essential role in insulin extraction and glucose production, but the specific role of hepatic cholinergic innervation remains unclear. We sought to establish a model of isolated hepatic cholinergic denervation (IHCD), and to assess whether glycogen storage or the control of net hepatic glucose production (HGP) was altered by IHCD. MATERIALS AND METHODS: Sprague-Dawley rats underwent either hepatic vagotomy or sham operation. Liver tissue was stained for vesicular acetylcholine transporter (VAChT) and (nonspecific neural) protein gene product 9. 5 (PGP) for verification of IHCD. Liver glycogen content was quantified in fed and fasted IHCD or sham-operated animals. HGP was determined after single-pass isolated liver perfusion, during which a 30-min 12 ng/ml glucagon infusion was begun after equilibration, and after 10 min, a 200 microU/ml insulin infusion was added. RESULTS: Uniform staining of PGP and absence of VAChT staining in hepatic vagotomized rats demonstrated the validity of our model. Glycogen content of sham-operated livers (n = 8) increased from 6.0 +/- 1.7 in the fasting state to 10.6 +/- 1.8 mg/g liver, after feeding (P < 0.05). IHCD livers (n = 8) showed no comparable increase (3.5 +/- 0.6 to 4.0 +/- 0.7 mg/g liver). Perfusion with glucagon alone resulted in less HGP in IHCD livers (n = 12) compared with sham-operated livers (n = 10) (integrated HGP 3.3 +/- 0.3 mg/g liver min(-1) vs 5.1 +/- 0.5 mg/g liver min(-1), P < 0.05). Insulin infusion revealed impaired responsiveness to insulin after IHCD; the ratio of HGP in the final 10 min of perfusion (glucagon and insulin) to HGP in the initial 10 min (glucagon alone) was 90.3 +/- 2.4% for IHCD livers versus 68.1 +/- 4.4% for sham-operated controls, respectively (P = 0.0002). CONCLUSIONS: Our study shows that IHCD results in significant impairment in liver glycogen storage and impaired hepatic sensitivity to glucagon and, possibly, to insulin. We conclude that hepatic cholinergic integrity is essential to normal hepatic glucose metabolism.

Animals↗
PubMed2000

Activation of p38 mitogen-activated protein kinase by formyl-methionyl-leucyl-phenylalanine in rat neutrophils.

The signaling pathways leading to p38 mitogen-activated protein kinase (MAPK) activation in formyl-methionyl-leucyl-phenylalanine (fMLP)-stimulated rat neutrophils were examined. Immunoblot analysis with antibodies against a phosphorylated form of p38 MAPK showed that fMLP-stimulated p38 MAPK activation was dependent on a pertussis toxin-sensitive G protein. Two phosphatidylinositol 3-kinase inhibitors, wortmannin and 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one (LY294002), did not affect the p38 MAPK activation. Phosphorylation of p38 MAPK was concentration dependently attenuated by a tyrosine kinase inhibitor, genistein, and by a Ca(2+)-dependent protein kinase C inhibitor, 13-cyanoethyl-12-methyl-6,7,12,13-tetrahydroindolo[2,3-a]pyrrolo[3 , 4-c]carbazole-7-one (Gö6976). However, the protein kinase C inhibitors with a broader spectrum, 2-[1-(3-dimethylaminopropyl)-5-methoxy-1H-indol-3-yl]-3-(1H-indol-3-y l)-maleimide (Gö6983) and 2-[1-(3-dimethylaminopropyl)-1H-indol-3-yl]-3-(1H-indol-3-yl)-maleimi de (GF109203X), had no inhibitory effect. fMLP-stimulated p38 MAPK phosphorylation was also reduced in cells pretreated with a phospholipase C inhibitor, 1-[6-((17beta-3-methoxyestra-1,3, 5(10)-trien-17-yl)amino)hexyl]-1H-pyrrole-2,5-dione (U73122), or preloaded with an intracellular Ca(2+) chelator, 1, 2-bis-(o-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid (BAPTA). We conclude that phosphorylation of p38 MAPK by fMLP stimulation in rat neutrophils is dependent on G(i/o) protein, nonreceptor tyrosine kinase, phospholipase C/Ca(2+), and probably Ca(2+)-dependent protein kinase C pathways.

Animals↗
PubMed2000

New lignan glycosides with potent antiinflammatory effect, isolated from Justicia ciliata.

Two new lignan glycosides, 4-O-[alpha-L-arabinopyranosyl-(1' "-->2' ')-beta-D-xylopyranosyl-(1' " '-->5' ')-beta-D-apiofuranosyl]diphyllin (1), named ciliatoside A (1), and 4-O-¿[beta-D-apiofuranosyl-(1' " "-->3' ")-alpha-L-arabinopyranosyl-(1' "-->2' ')][beta-D-xylopyranosyl-(1' " '-->5' ')]-beta-D-apiofuranosyl¿diphyllin (2), named ciliatoside B (2), were isolated from the whole plant of Justicia ciliata. The structures of 1 and 2 were determined by spectral and chemical methods. Compounds 1 and 2 strongly inhibited the accumulation of NO(2)(-) in lipopolysaccharide-stimulated RAW 264.7 cells in a concentration-dependent manner with IC(50) values of 27.1 +/- 1.6 and 29.4 +/- 1.4 microM, respectively.

Animals↗
PubMed2000

Role of MAP kinase in the enhanced cell proliferation of long term estrogen deprived human breast cancer cells.

Women with estrogen receptor (ER) positive breast cancers frequently respond initially to inhibition of estrogen action but later relapse with re-growth of tumor. Previously, we have utilized MCF-7 human breast cancer cells deprived of estradiol long term (LTED cells) as the model system to study the regrowth phenomenon and have demonstrated that these cells exhibited increased cell proliferation rate and increased ER functionality during the adaptive processes. In this report, we examined the hypothesis that the mitogen-activated protein kinase (MAP kinase) signal was involved. We found that activated MAP kinase was elevated in LTED cells and that the MAP kinase specific inhibitor PD98059 was able to inhibit the elevated MAP kinase and [3H]thymidine uptake in LTED cells, suggesting mediation of DNA synthesis and proliferation by the MAP kinase pathway. Other MAP kinase upstream inhibitors, including genestein, RG13022, and mevastatin were also able to inhibit the [3H]thymidine uptake in LTED cells. Interestingly, the antiestrogen, ICI 182,780 was able to block the activated MAP kinase in LTED cells. Treatment with PD98059 did not block elevated basal ERE-CAT activity while at the same time inhibiting [3H]thymidine uptake in LTED cells. Furthermore, treatment with PD98059 partially blocked the E2-stimulated ERE-CAT activity and [3H]thymidine uptake in both LTED and in wild type cells, indicating that both MAP kinase-dependent and MAP kinase-independent pathways are involved in the transactivation function of ER. Taken together, our data suggest that the MAP kinase pathway is, in part, involved in the adaptive process which results in enhanced DNA synthesis and cell proliferation in the absence of exogenous estrogen in LTED cells.

Breast Neoplasms↗
PubMed2000

Pharmacokinetics and antitumor effect of doxorubicin carried by stealth and remote loading proliposome.

PURPOSE: The aim of the study was to prepare stealth and remote loading proliposome (SRP-L) to carry doxorubicin (DXR) and evaluate the pharmacokinetics, acute toxicity, and anticancer effect of DXR carried with SRP-L. METHODS: SRP-L was transparent solution. When SRP-L was injected into 0.9%, NaCl aqueous solution containing DXR. liposomes formed and automatically loaded DXR (SRP-L-DXR). The long circulation of SRP-L-DXR was evaluated using the pharmacokinetics of SRP-L-DXR. cardiolipin liposomal DXR (CL-DXR) and free DXR (F-DXR). The acute toxicity and anticancer effect of SRP-L-DXR were evaluated in C57BL/6 mice and murine hystocytoma M5076 tumor model. RESULTS: The average diameter of SRP-L-DXR in pure water was 112.9 +/- 8.6 (nm) and the encapsulation efficiency of SRP-L-DXR was 96.5 +/- 0.2% in pure water, 95.5 +/- 0.1% in 5% glucose and 98.01 +/- 0.6% in 0.9% NaCl. The plasma concentration of SRP-L-DXR was much higher than those of F-DXR and CL-DXR. Compared with that of F-DXR, the SRP-L-DXR had lower acute toxicity and its anticancer effects depended upon the therapeutic treatment. CONCLUSIONS: A novel proliposome (SRP-L) was developed, which could automatically load DXR and form SRP-L-DXR with excellent characteristics. SRP-L-DXR had lower acute toxicity but was not always more effective for the treatment of the ascitic M5076 than F-DXR.

Animals↗
PubMed2000

Mitochondrial DNA phylogeography of Acrossocheilus paradoxus (Cyprinidae) in Taiwan.

Nucleotide sequences of 3' end of the cytochrome b gene, tRNA genes, D-loop control region, and the 5' end of the 12S rRNA of mitochondrial DNA (mtDNA) were used to assess the genetic and phylogeographic structure of Acrossocheilus paradoxus populations, a Cyprinidae fish of Taiwan. A hierarchical examination of populations in 12 major streams from three geographical regions using an analysis of molecular variance (AMOVA) indicates high genetic differentiation both among populations (PhiST = 0.511, P < 0.001) and among regions (PhiCT = 0.368, P < 0.001). Limited migration largely contributed to the genetic differentiation. High nucleotide diversity (1.13%) and haplotype diversity (0.80%) were detected among populations. The degree of genetic differentiation was correlated with geographical distance between populations, a result consistent with the one-dimensional stepping stone models. A neighbour-joining tree recovered by (DAMBE) supports the pattern of isolation by distance and reveals a closer relationship between populations of the central and southern regions. A minimum spanning network based on nucleotide substitutions reflected migration routes from populations of the central region to the northern and southern regions, respectively. Postglacial colonization and expansion can explain the phylogeographical pattern. Single and ancient migration events may have allowed the northern region to attain the monophyly of mtDNA alleles. In contrast, most populations within geographical regions are either paraphyletic or polyphyletic due to the relatively shorter time period for coalescence. Both low haplotype number and genetic variability suggest a bottleneck event in the Chingmei population of northern Taiwan. Based on coalescence theory, the monophyly of the Tungkang population of the southern region may be associated with a founder event.

Animals↗
PubMed2000

Bursal sporotrichosis: case report and review.

We describe a patient whose prepatellar bursa was infected with Sporothrix schenckii. The infection persisted despite itraconazole therapy and cure was achieved only after surgical excision of the bursa. A review of treatments for bursal sporotrichosis is presented.

Bursa, Synovial↗
PubMed2000

Estradiol hypersensitivity and mitogen-activated protein kinase expression in long-term estrogen deprived human breast cancer cells in vivo.

Women with breast cancer who have responded to initial hormonal therapy frequently experience additional remissions upon further endocrine manipulation. We postulate that hypersensitivity to estradiol (E2) may serve as a mechanistic explanation for these secondary responses. We previously provided evidence of hypersensitivity using an in vitro breast cancer model system and demonstrated the role of mitogen-activated protein kinase (MAP kinase) in the process of adaptation to long-term estradiol deprivation. In the present study, we wished to demonstrate that hypersensitivity to E2 could occur under more complex in vivo conditions and that MAP kinase activation is enhanced under these circumstances. We used an MCF-7 breast cancer model system involving long-term estradiol deprived (LTED) cells to produce xenografts in nude mice and an E2 clamp method to precisely control sex steroid levels. The E2 clamp was designed to maintain plasma E2 at a series of doubling doses from 1.25 pg/ml to 20.0 pg/ml in oophorectomized nude mice. As evidence of the validity of the clamp method, a uterine weight bioassay revealed an excellent, linear dose-response relationship between the predicted level of plasma E2 and stimulation of uterine weight. As evidence of hypersensitivity, we found that LTED xenograft tumors grew to a greater extent than wild-type in response to E2 concentrations of 1.25 pg/ml (P = 0.003) and 2.5 pg/ml (P = 0.0002). At the 10.0 and 20.0 pg/ml plasma concentrations, the LTED tumors were stimulated to a lesser extent than the wild-type. This pattern of increased growth at lower concentrations and reduced growth vs. the wild-type at higher concentrations mimics closely the pattern seen for LTED cells in vitro. All LTED cell tumors exhibited enhanced activation of MAP kinase ranging from 18 to 25%, and E2 did not increase this further. In contrast, E2 caused a linear increase in the percentage of activated MAP kinase positive cells (P < 0.0001) in wild-type tumors from basal levels of 2.66% to maximal levels of 6.40%. These observations suggest a dynamic interplay whereby activation of MAP kinase renders cells more sensitive to the proliferative effects of E2. The precise mechanisms for this interplay are unknown but, when further understood, could potentially provide insight into approaches to prevent the evolution of tumors to a hormone insensitive state.

Animals↗
PubMed2000

Synthesis and anti-inflammatory effect of chalcones.

The process of degranulation of mast cells and neutrophils contributes to inflammatory disorders. Activation of microglial cells and macrophages is believed to be involved in inflammatory, infectious and degenerative diseases of the CNS. Combining the potent inhibition of chemical mediators released by the degranulation of mast cells or neutrophils and from the activated microglial cells or macrophages, would lead to a promising anti-inflammatory agent for the treatment of peripheral and central inflammation. A series of chalcone derivatives have been reported to have potent anti-inflammatory activity. In an effort to continually develop potent anti-inflammatory agents, novel series of chalcones, 2'-hydroxy- and 2',5'-dihydroxychalcones were synthesized and their inhibitory effects on the activation of mast cells, neutrophils, microglial cells and macrophages were evaluated in-vitro. The chalcones were prepared by Claisen-Schmidt condensation of appropriate acetophenones with an appropriate aromatic aldehyde. The alkoxychalcones were prepared with appropriate hydroxychalcones and alkyl iodide and the dihydroxychalcones were prepared by hydrogenation of an appropriate chalcone with Pd/C. Almost all of the hydroxychalcones exhibited potent inhibitory effects on the release of beta-glucuronidase and lysozyme from rat neutrophils stimulated with formyl-Met-Leu-Phe/cytochalasin B (fMLP/CB). Of the hydroxychalcones, compound 1 was the most potent inhibitor of the release of beta-glucuronidase (IC50=1.6+/-0.2 microM) and lysozyme (IC50=1.4+/-0.2 microM) from rat neutrophils stimulated with fMLP/CB. Almost all of the 2',5'-dialkoxychalcones exhibited potent inhibitory effects on nitric oxide (NO) formation from murine microglial cell lines N9 stimulated with lipopolysaccharide (LPS). Of these, compound 11 showed the greatest effect (IC50=0.7+/-0.06 microM). The present results demonstrated that most of the chalcone derivatives have an anti-inflammatory effect. The inhibitory effects of dialkoxychalcones, 10-12 on inflammation are probably not due to the inhibition of mast cells and neutrophil degranulation, but are mediated through the suppression of NO formation from N9 cells.

Animals↗
PubMed2000

The upstream regulation of p38 mitogen-activated protein kinase phosphorylation by arachidonic acid in rat neutrophils.

The signal transduction pathways activated by arachidonic acid that lead to p38 mitogen-activated protein kinase (MAPK) activation in neutrophils remains unclear. In this study, selective inhibitors of several signalling pathways were utilized to investigate the mechanisms of activation of p38 MAPK by arachidonic acid in rat neutrophils. Stimulation of p38 MAPK phosphorylation by arachidonic acid and its trifluoromethyl ketone analogue AACOCF3 was transient, peaking at 1 min, and was concentration-dependent. Arachidonic acid-stimulated p38 MAPK phosphorylation was attenuated in cells pretreated with the Gi/o inhibitor (pertussis toxin), but not with the dual cyclooxygenase/lipoxygenase inhibitor (BW755C) or the leukotriene biosynthesis inhibitor (MK886). Tyrosine kinase inhibitor (genistein), but not the extracellular signal-regulated kinase kinase inhibitors (PD98059 and U0126), attenuated the phosphorylation of p38 MAPK by arachidonic acid. Phosphoinositide 3-kinase inhibitors (wortmannin and LY294002) did not affect the arachidonic acid-induced response. After pretreatment of the cells with protein kinase C inhibitors (Gö6976, Gö6983 and GF109203X), only Gö6976 significantly attenuated the phosphorylation of p38 MAPK by arachidonic acid. In addition, phosphorylation of p38 MAPK by arachidonic acid was greatly attenuated by the phospholipase C inhibitor (U73122) and the Ca2+ chelator BAPTA ((1,2-bis-o-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid), but not altered by the nitric oxide synthase inhibitor, N-nitro-L-arginine methyl ester. Arachidonic acid did not cause an increase in cellular cyclic GMP level. This study revealed the involvement of pertussis toxin-sensitive G protein, non-receptor tyrosine kinase, phospholipase C/Ca2+, and probably Ca2+-dependent protein kinase C in arachidonic acid-stimulated p38 MAPK activation.

Animals↗
PubMed2000

Synthesis and anti-platelet, anti-inflammatory and anti-allergic activities of methoxyisoflavanquinone and related compounds.

In a continuation of our search for novel anti-platelet agents, isoflavone quinone and isoflavanquinone were selected as lead compounds and the synthesis of their methoxy derivatives was carried out. Among them, the 4'- and 7-methoxy derivatives were successfully prepared, whereas the attempt to obtain 3'-methoxy derivatives resulted in their isomers, 3'-methoxyflavone quinone and 3'-methoxyflavanquinone, instead. After screening for their anti-platelet, anti-inflammatory and anti-allergic activities, a preliminary structure-activity relationship was established. Compounds 6c, 7a-c, 8c and 9a-c were found to exhibit significant activities. In particular, compound 7c demonstrated very potent anti-platelet, anti-inflammatory and anti-allergic activities and was then recommended for further pharmacological investigation.

Animals↗
PubMed1999

Differential expression of beta-amyloid precursor and Bcl-2 proto-oncogene proteins in the developing dog retina.

Previous studies of rat retinas have not only provided evidence that beta-amyloid precursor (APP) and B-cell lymphoma proto-oncogene (Bcl-2) proteins are colocalized in retinal Müller glial cells, but have also indicated that common mechanisms regulate their expression in these cells (Chen, S.T., Garey, L.J., Jen, L.S., 1994. Bcl-2 proto-oncogene protein immunoreactivity in normally developing and axotomised rat retinas. Neurosci. Lett. 172, 11 14; Chen, S.T., Gentleman, S.M., Garey, L.J., Jen, L.S., 1996. Distribution of beta-amyloid precursor and B-cell lymphoma proto-oncogene proteins in the rat retina after optic nerve transection or vascular lesion. J. Neuropathol. Exp. Neurol. 55, 1073-1082; Chen, S.T., Garey, L.J., Jen, L.S., 1997. Expression of beta-amyloid precursor protein immunoreactivity in the retina of the rat during normal development and after neonatal optic tract lesion. NeuroReport 8, 713-717). This investigation attempts to resolve whether or not the pattern observed in rats also applies to other higher mammalian species by examining the expression of immunoreactivity to APP and Bcl-2 in developing as well as mature dog retinas using immunocytochemical methods. Experimental results indicate that the immunoreactivity of both APP and Bcl-2 is located primarily in the inner retina, particularly in the ganglion cells and their axons in late fetal and neonatal stages. From the second postnatal week (the time of eye opening) onwards, immunoreactivity to APP, but not Bcl-2, is localized primarily in the endfeet and proximal part of the radial process of retinal Müller glial cells. Although the findings show both APP and Bcl-2 are expressed in ganglion cells and their processes suggest that the molecules have a role in the differentiation of neurons in the central nervous tissue, the lack of Bcl-2 in the Müller glial cells in dog retinas further suggests that the two molecules may have different biological roles with respect to glial function.

Amyloid beta-Protein Precursor↗
PubMed1999

Hammerhead ribozyme cleavage of apolipoprotein B mRNA generates a truncated protein.

Target substrate-specific hammerhead ribozyme cleaves the specific mRNA and results in the inhibition of gene expression. In humans, overproduction of apolipoprotein B (apoB) is positively associated with premature coronary artery diseases. To modulate apoB gene expression, we designed hammerhead ribozymes targeted at AUA(6665) and GUA(6679) of apoB mRNA, designated RB16 and RB15, respectively, and investigated their effects on apoB mRNA in HepG2 cells. The results demonstrated that RB15 and RB16 ribozyme RNAs cleaved apoB RNA efficiently in vitro. Both ribozymes, RB15 and RB16, were used to construct recombinant adenoviral vectors, designated AvRB15 and AvRB16, respectively, for in vivo gene transfer. HepG2 cells were infected with 2 x 10(5) plaque-forming units of AvRB15 for 5, 10, 15, and 24 h. An RNase protection assay showed that the expression of the RB15 transcript was time-dependent; it increased approximately 300-fold from 5 to 24 h. Using reverse ligation-mediated polymerase chain reaction, the 3' cleavage product of apoB mRNA was detected, and the exact cleavage site of apoB mRNA was confirmed by sequencing. Importantly, the levels of apoB mRNA in HepG2 cells decreased approximately 80% after AvRB15 infection. Pulse/chase experiments on HepG2 cells treated with AvRB15 and AvRB16 demonstrated that ribozyme cleavage produced a truncated protein that was secreted at a density of 1. 063-1.210 g/ml. The cleavage activity of RB15 on apoB mRNA was more efficient than that of RB16. Moreover, pulse/chase experiments in HepG2 cells treated with AvRB15 revealed that most of the truncated apoB protein was degraded intracellularly. We conclude that hammerhead ribozyme targeted at GUA(6679) of apoB mRNA cleaves apoB mRNA, results in decreased apoB mRNA levels, and generates a truncated apoB of the expected size in vivo. Thus, the therapeutic application of ribozyme in regulating apoB production holds promise.

Adenoviridae↗
PubMed1999

Chemistry and biological activities of constituents from Morus australis.

A novel constituent named australone B (1) was further isolated from the cortex of Morus australis (Moraceae). The structure of 1 has been elucidated by one- and two-dimension spectra. In human citrated platelet-rich plasma, 1 showed strong inhibition of aggregation induced by adrenaline in a concentration-dependent manner with an IC(50) value of about 33.3 microM. Compound 1 (30 microM) also showed inhibitory effects on superoxide anion formation from rat neutrophils stimulated with formyl-Met-Leu-Phe (fMLP)/cytochalasin B (CB). Morusin (2) inhibited superoxide anion formation from rat neutrophils stimulated with phorbol myristate acetate (PMA) in a concentration-dependent manner with an IC(50) value of 66.9+/-2.5 microM.

Animals↗
PubMed1999

Examination of the signal transduction pathways leading to activation of extracellular signal-regulated kinase by formyl-methionyl-leucyl-phenylalanine in rat neutrophils.

The signaling pathways leading to extracellular signal-regulated kinase (ERK) activation in formyl-methionyl-leucyl-phenylalanine (fMLP)-stimulated rat neutrophils were examined. fMLP-stimulated ERK activation based on immunoblot analysis with antibodies against the phosphorylation form of ERK was attenuated by the pretreatment of cells with pertussis toxin but not with a dual cyclo-oxygenase/lipoxygenase inhibitor BW755C. Exposure of cells to the tyrosine kinase inhibitor genistein, phosphatidylinositol 3-kinase (PI3K) inhibitors wortmannin and LY294002, or protein kinase C (PKC) inhibitors Gö6976, Gö6983, and GF109203X inhibited fMLP-stimulated ERK phosphorylation in a concentration-dependent manner. In addition, both the phospholipase C (PLC) inhibitor U73122 and the Ca2+ chelator BAPTA attenuated ERK activation. These results indicate that G(i/o) protein, tyrosine kinase, P13K, PKC, and PLC/Ca2+, but not arachidonate metabolites, act upstream of fMLP-stimulated ERK activation.

Animals↗
PubMed1999

Binding forces of hepatic microsomal and plasma membrane proteins in normal and pancreatitic rats: an AFM force spectroscopic study.

The docking and fusion of membrane-bound vesicles at the cell plasma membrane are brought about by several participating vesicle membrane, plasma membrane, and soluble cytosolic proteins. An understanding of the interactions between these participating proteins will provide an estimate of the potency and efficacy of secretory vesicle docking and fusion at the plasma membrane in cells of a given tissue. Earlier studies suggest that in chronic pancreatitis, glucose intolerance may be associated with impaired exocytosis/endocytosis of hepatic insulin receptor and glucose transporter proteins. In this study, the binding force profiles between microsome membrane proteins and plasma membrane proteins in liver obtained from normal and pancreatitic rats have been examined using atomic force microscopy. The ability of a VAMP-specific antibody to alter binding between microsome- and plasma membrane-associated membrane proteins was examined. In pancreatitic livers, a significant loss in microsome-plasma membrane binding is observed. Furthermore, our study shows that, in contrast to control livers, the microsome-plasma membrane binding in pancreatitic livers is VAMP-independent, which suggests an absence of VAMP participation in membrane-microsome binding. In confirmation with our earlier findings, these studies suggest altered membrane recycling in liver of rats with chronic pancreatitis.

Animals↗
PubMed1999

Expression of beta-amyloid precursor and Bcl-2 proto-oncogene proteins in rat retinas after intravitreal injection of aminoadipic acid.

In order to investigate the role of glia in relation to factors that affect the expression of beta-amyloid precursor protein (betaAPP) and B cell lymphoma oncogene protein (Bcl-2) in the central nervous tissue, the patterns of expression of betaAPP and Bcl-2 in developing and mature rat retinas were studied immunocytochemically after intravitreal injection of alpha-aminoadipic acid (alpha-AAA), a glutamate analogue and gliotoxin that is known to cause injury of retinal Müller glial cells. In normal developing retinas, betaAPP and Bcl-2 were expressed primarily but transiently in a small number of neurons in the ganglion cell layer during the first postnatal week. Immunoreactivity of betaAPP and Bcl-2 appeared in the endfeet and proximal part of the radial processes of Müller glial cells from the second postnatal week onwards. In rats that received intravitreal injection of alpha-AAA at birth, there was a loss of immunoreactivity to vimentin, and a delayed expressed on betaAPP or Bcl-2 in Muller glial cells until 3-5 weeks post-injection. Immunoreactive neurons were also observed in the inner retina especially in the ganglion cell layer from 5 to 35 days after injection. A significant reduction in numerical density of cells with large somata in the ganglion cell layer was observed in the neonatally injected retinas at P56, which was accompanied by an increased immunostaining in radial processes of Müller glial cells. In contrast, no detectable changes in the expression of betaAPP and Bcl-2 were observed in retina that received alpha-AAA as adults. These results indicate that the gliotoxin alpha-AAA has long lasting effects on the expression of betaAPP and Bcl-2 in Müller glial cells as well as neurons in the developing but not mature retinas. The loss of vimentin and delayed expression of betaAPP and Bcl-2 in developing Müller glial cells suggests that the metabolic integrity of Müller cells was temporarily compromised, which may have adverse effects on developing neurons that are vulnerable or dependent on trophic support from the Müller glial cells.

2-Aminoadipic Acid↗