NF-kappa B activation by tumor necrosis factor and interleukin-1.
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Adaptor Proteins, Signal Transducing↗
Biomedical subjects
Z Cao
Publications and source records attributed to Z Cao.
Propionate and butyrate esters of camptothecin and 9-nitrocamptothecin as antileukemia prodrugs in vitro.
Six camptothecin (CPT) alkyl esters and four 9-nitrocamptothecin (9NC) alkyl esters were assayed for ability to inhibit proliferation and induce programmed cell death (apoptosis) in human leukemia HL-60 and U-937 cells, which exhibit differential sensitivity to CPT and 9NC. In general, CPT-propionate and CPT-butyrate demonstrated activities, while the other esters were practically inactive. Similarly, 9NC-propionate and 9NC-butyrate were active, while the other 9NC esters exhibited little or no activity. The biologically active esters required metabolic conversion (i.e., de-esterification) to their parental compounds as demonstrated by the conversion of CPT-propionate to CPT in mouse liver homogenate, and the topoisomerase I-inhibition assay. In conclusion, the propionate and butyrate esters of CPT and 9NC are CPT and 9NC prodrugs, that can develop to important chemotherapeutic agents for the effective treatment of human leukemias and other malignancies.
Animals↗
Mutant cells that do not respond to interleukin-1 (IL-1) reveal a novel role for IL-1 receptor-associated kinase.
Mutagenized human 293 cells containing an interleukin-1 (IL-1)-regulated herpes thymidine kinase gene, selected in IL-1 and gancyclovir, have yielded many independent clones that are unresponsive to IL-1. The four clones analyzed here carry recessive mutations and represent three complementation groups. Mutant A in complementation group I1 lacks IL-1 receptor-associated kinase (IRAK), while the mutants in the other two groups are defective in unknown components that function upstream of IRAK. Expression of exogenous IRAK in I1A cells (I1A-IRAK) restores their responsiveness to IL-1. Neither NFkappaB nor Jun kinase is activated in IL-1-treated I1A cells, but these responses are restored in I1A-IRAK cells, indicating that IRAK is required for both. To address the role of the kinase activity of IRAK in IL-1 signaling, its ATP binding site was mutated (K239A), completely abolishing kinase activity. In transfected I1A cells, IRAK-K239A was still phosphorylated upon IL-1 stimulation and, surprisingly, still complemented all the defects in the mutant cells. Therefore, IRAK must be phosphorylated by a different kinase, and phospho-IRAK must play a role in IL-1-mediated signaling that does not require its kinase activity.
Cell Line, Transformed↗
Role of angiotensin receptor subtypes in mesenteric vascular proliferation and hypertrophy.
The aim of this study was to explore the regulation of angiotensin receptors after chronic infusion with angiotensin II (Ang II) and to clarify the relative roles of the angiotensin type 1 (AT(1)) and type 2 (AT(2)) receptors in the mediation of Ang II-induced mesenteric vascular hypertrophy. In male Sprague-Dawley rats, Ang II infusion at a dose of 58.3 ng/min by subcutaneous osmotic minipumps for 14 days led to increased mesenteric weight and wall:lumen ratio of the vessels and proliferation of smooth muscle cells. These vascular changes were attenuated by either valsartan, an AT(1) receptor antagonist, at a dose of 30 mg. kg(-1). d(-1) by gavage, or PD123319, an AT(2) receptor antagonist, at a dose of 830 ng/min by intraperitoneally implanted osmotic minipumps. Ang II infusion was associated with hypertension, which was prevented by valsartan, but not PD123319. (125)I-Sar(1), Ile(8) Ang II binding to mesenteric vasculature was increased after Ang II infusion. Valsartan treatment was associated with reduced Ang II binding to both receptor subtypes, whereas PD123319 was associated with reduced Ang II binding to only the AT(2) receptor subtype. These findings suggest that the trophic and proliferative effects of Ang II on the mesenteric vasculature are mediated by both AT(1) and AT(2) receptors.
Angiotensin II↗
Comparison of tacrolimus concentrations measured by the IMx tacrolimus II vs the PRO-TRAC II FK506 ELISA assays.
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Enzyme-Linked Immunosorbent Assay↗
[The contrast between chemotherapy via pelvic retroperitoneal cannulation and intraperitoneal chemotherapy in gynecological malignancies cancers with lymph node metastases].
OBJECTIVE: To contrast the pelvic retroperitoneal (RP) chemotherapy with intraperitoneal (i.p.) chemotherapy in gynecological malignancies with lymph node metastases. METHODS: Fluorouracil (5-FU) was repeatedly injected into the pelvic retroperitoneal space of 43 patients and the abdominal cavity of 11 patients. High performance liquid chromatography was used to determine the drug concentration of 5-FU. 5-FU was repeatedly injected into the pelvic retroperitoneal space of 16 patients via cannulation to observe the nodal 5-FU concentration of injected side and the control side. 99mTc-Sb2S3, Isovist-300 were injected into the pelvic retroperitoneal space of two groups (each one has 3 patients) respectively via cannulation. Single proton emission computer tomography (SPECT) and X-Ray film were taken to observe the allocation of the drugs. RESULTS: (1) Pelvic and periaortic nodal 5-FU concentrations of RP were 60-106 and 76-119 times of that of i.p. respectively. (2) The nodal 5-FU concentrations on repeated injection side were 16-20 times of that on control sides of RP. (3) There was no complications or adverse effect observed. (4) 5-FU was allocated to the space including the external iliac, internal iliac, obturator, deep inguinal and common iliac lymph nodes and also up to the periaortic lymph nodes. CONCLUSION: RP was more effective than i.p. for the treatment of lymphatic metastasis of gynecologic cancer.
Antimetabolites, Antineoplastic↗
[Introducing the 21st century by modernizing the obstetrics and gynecology--the 50 years' achievement and prospect of the obstetrics and gynecology].
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China↗
[The effects of lead poisoning on expression of nerve growth factor gene of submandibular gland in mice].
OBJECTIVE: To study the toxicity of lead poisoning to submandibular gland and its effects on nerve growth factor (NGF) gene expression in mice. METHODS: An experimental model with lead poisoning was established and its histopathological changes in the submandibular gland of mice were observed under light and electronic microscopes. Effects of lead poisoning on expression of NGF mRNA in submandibular gland were analyzed quantitatively by human NGF DNA probe labelled with digoxin with in situ hybridization. RESULTS: Body weight of the mice with experimental lead poisoning reduced, and their lead levels in blood and submandibular gland increased. Lobular atrophy, fibrous hypertrophy, angiectasis of the stroma and enlargement of lobule interstitial in mouse submandibular gland with lead poisoning could be found under light and electron microscopes. Their rough surfaced endoplasmic reticulum was extended and mitochondrion swollen. Graphic analysis showed that diameters of the secretory striate ducts and granular tubules decreased in the mice with lead poisoning. Results of in situ hybridization indicated that hybridized signals in the granular and secretory striate ducts and granular tubules reduced significantly, and NGF mRNA expression decreased. CONCLUSION: Lead is toxic to the submandibular gland of mice and can affect their NGF gene expression.
Animals↗
[Microvessel count in normal cervical tissue and in cervical carcinomas].
This study was conducted to determine microvessel count(MVC) status in normal cervical tissue (NCT) and in cervical carcinomas (CCs). 15 cases of NCT and 80 cases of CCs were stained by immunohistochemical method for Factor VIII related antigen (F8RA). The results showed that the MVC in CCs was much higher than that in NCT and it was correlated with clinical stage, size of tumor and lymph node status (P < 0.05). Every time when MVC increased by 5 in number (LM x 200, field 0.739 mm2), the chance of lymph node metastasis increased by 1.61 times. There was no relationship between MVC and tumor grade. These suggested that MVC might be a useful early parameter in the diagnosis and prognosis of CCs.
Carcinoma, Squamous Cell↗
[Changes of placental nitric oxide synthase in patients with pregnancy induced hypertension].
The objective of this study was to determine whether the expression of placental endothelial nitric oxide synthase (eNOS) and/or inducible nitric oxide synthase (iNOS) are changed in pregnancy induced hypertension (PIH). The placentas of 32 patients with PIH and 32 normal pregnancies were studied by immunohistochemistry (Avidin-Biotin-Complex method). The results showed there were eNOS and iNOS antigens in placental tissues from PIH and normal pregnancy. They were all localized in placental villi and syncytiotrophoblast cells. The expression of placenta eNOS decreased significantly in patients with PIH as compared with that of normal pregnancy. The expression of placenta eNOS in mild PIH was higher than that of moderate or severe PIH (P < 0.025, P < 0.005, respectively). There was a negative correlation between blood pressure and the expression of eNOS in placenta (P < 0.0005). There was no significant difference between the expression of iNOS in placenta with PIH and that in normal pregnancy. Also, there was no significant difference of the expression of iNOS in placenta between the mild and moderate PIH, or the mild and severe PIH. Furthermore, there was no correlation between blood pressure and the expression of iNOS in placenta with PIH. It is concluded that the decrease of the expression of eNOS in placenta may be associated with the pathogenesis of PIH.
Adult↗
[Cervical lymph node metastasis and recurrence in supraglottic carcinoma after operation].
OBJECTIVE: To evaluate the regional control efficacy of elective neck dissection (END) in patients with supraglottic carcinoma. METHODS: The incidence of cervical recurrences of 582 patients with supraglottic carcinoma treated in this hospital from 1981 to 1993 were retrospectively reviewed. RESULTS: Three hundred and ninety-two cases (67.35%) of this group had T3 and T4 primary lesions. Among them, 147 cases (37.50%) had positive nodes(N+) and this accounted for 86.47% (147/170) of all N+ patients. Ipsilateral or bilateral cervical recurrence occurred in 33 of 126 (26.19%) node negative (N0) cases who had not had neck dissection and 30 of them (90.90%) were among T3 and T4 groups. However, Contralateral lymph node recurrence occurred only in 40 of 286(13.99%) N0 cases who had had END and 30 of them (75%) were among T3 and T4 groups. There were 163 cases who were readmitted and received surgery again for different purposes. The three and five year survival rates in the second stage END group were 86.67% and 77.78%, in metastasis group 64.81% and 32.50%, in recurrent group 33.33% and 30.77% respectively. There were significant differences in survival rates among these groups. CONCLUSION: Patients underwent elective neck dissection achieved better survival than those on "wait and watch" policy and salvage surgery. Elective neck dissection is recommended for the treatment of supraglottic carcinoma, especially for the T3 and T4 diseases.
Adult↗
Identification of a domain on the integrin alpha5 subunit implicated in cell spreading and signaling.
The alpha5 beta1 integrin is a cell surface receptor for fibronectin implicated in several cellular activities including cell proliferation, differentiation, and migration. The primary site at which the alpha5 beta1 integrin interacts with fibronectin is the RGD (Arg-Gly-Asp) amino acid sequence. In general, the sites on the integrin alpha subunits involved in ligand binding are not well characterized. Based on previous cross-linking studies, sequence alignment, predicted conformation, and intron-exon boundaries, we identified a 144-residue region (positions 223-367) on the alpha5 subunit as a putative binding region and divided it into four subdomains named domains I, II, III, and IV. Chimeric receptors were prepared in which sequences on the alpha5 subunit were exchanged with the corresponding sequences on the alpha6 subunit, which is specific for laminin and does not bind via an RGD sequence. The mutated human alpha5 integrin gene was transfected into CHO B2 cells, which are deficient in alpha5 expression. Only chimeras of domain III or IV express on the cell surface. Both of these chimeras decreased the adhesion, spreading, focal adhesion assembly, and migration on fibronectin. The adhesion of the chimeric receptors to fibronectin remained sensitive to the RGD peptide, and antibodies that inhibit interaction with the fibronectin synergy site and RGD loop remain inhibitory for the chimeras, indicating that our chimeras do not inhibit binding to either the RGD or synergy sites. Finally, the affinity of soluble fibronectin to cells via the alpha5 beta1 receptor decreased only about 3-fold. This decrease is substantially less than the observed effects on migration and spreading, which were not altered by changes in substrate concentration. Thus, the alteration in binding sites does not easily account for the changes in cell spreading and focal adhesion assembly. The tyrosine phosphorylation and focal adhesion assembly that are seen when cells expressing the wild type alpha5 receptor adhere to fibronectin were inhibited in cells expressing the chimeric receptors. Therefore, our results suggest that the chimeras of these domains likely interrupt alpha5-mediated conformational signaling.
Amino Acid Sequence↗
Structural and functional characterization of Streptomyces plicatus beta-N-acetylhexosaminidase by comparative molecular modeling and site-directed mutagenesis.
We have sequenced the Streptomyces plicatus beta-N-acetylhexosaminidase (SpHex) gene and identified the encoded protein as a member of family 20 glycosyl hydrolases. This family includes human beta-N-acetylhexosaminidases whose deficiency results in various forms of GM2 gangliosidosis. Based upon the x-ray structure of Serratia marcescens chitobiase (SmChb), we generated a three-dimensional model of SpHex by comparative molecular modeling. The overall structure of the enzyme is very similar to homology modeling-derived structures of human beta-N-acetylhexosaminidases, with differences being confined mainly to loop regions. From previous studies of the human enzymes, sequence alignments of family 20 enzymes, and analysis of the SmChb x-ray structure, we selected and mutated putative SpHex active site residues. Arg162 --> His mutation increased Km 40-fold and reduced Vmax 5-fold, providing the first biochemical evidence for this conserved Arg residue (Arg178 in human beta-N-acetylhexosaminidase A (HexA) and Arg349 in SmChb) as a substrate-binding residue in a family 20 enzyme, a finding consistent with our three-dimensional model of SpHex. Glu314 --> Gln reduced Vmax 296-fold, reduced Km 7-fold, and altered the pH profile, consistent with it being the catalytic acid residue as suggested by our model and other studies. Asp246 --> Asn reduced Vmax 2-fold and increased Km only 1.2-fold, suggesting that Asp246 may play a lesser role in the catalytic mechanism of this enzyme. Taken together with the x-ray structure of SmChb, these studies suggest a common catalytic mechanism for family 20 glycosyl hydrolases.
Amino Acid Sequence↗
Role of carbohydrate-mediated adherence in cytopathogenic mechanisms of Acanthamoeba.
Acanthamoeba keratitis is a vision-threatening corneal infection. The mannose-binding protein of Acanthamoeba is thought to mediate adhesion of parasites to host cells. We characterized the amoeba lectin with respect to its carbohydrate binding properties and the role in amoeba-induced cytopathic effect (CPE). Sugar inhibition assays revealed that the amoeba lectin has the highest affinity for alpha-Man and Man(alpha1-3)Man units. In vitro cytopathic assays indicated that mannose-based saccharides which inhibit amoeba adhesion to corneal epithelial cells were also potent inhibitors of amoeba-induced CPE. Another major finding was that N-acetyl-D-glucosamine (GlcNAc) which does not inhibit adhesion of amoeba to host cells is also an inhibitor of amoeba-induced CPE. The Acanthamoebae are thought to produce CPE by secreting cytotoxic proteinases. By zymography, one metalloproteinase and three serine proteinases were detected in the conditioned media obtained after incubating amoebae with the host cells. The addition of free alpha-Man and GlcNAc to the co-culture media inhibited the secretion of the metalloproteinase and serine proteinases, respectively. In summary, we have shown that the lectin-mediated adhesion of the Acanthamoeba to host cells is a prerequisite for the amoeba-induced cytolysis of target cells and have implicated a contact-dependent metalloproteinase in the cytopathogenic mechanisms of Acanthamoeba.
Acanthamoeba↗
NF-kappaB-inducing kinase activates IKK-alpha by phosphorylation of Ser-176.
Activation of the transcription factor NF-kappaB by inflammatory cytokines involves the successive action of NF-kappaB-inducing kinase (NIK) and two IkappaB kinases, IKK-alpha and IKK-beta. Here we show that NIK preferentially phosphorylates IKK-alpha over IKK-beta, leading to the activation of IKK-alpha kinase activity. This phosphorylation of IKK-alpha occurs specifically on Ser-176 in the activation loop between kinase subdomains VII and VIII. A mutant form of IKK-alpha containing alanine at residue 176 cannot be phosphorylated or activated by NIK and acts as a dominant negative inhibitor of interleukin 1- and tumor necrosis factor-induced NF-kappaB activation. Conversely, a mutant form of IKK-alpha containing glutamic acid at residue 176 is constitutively active. Thus, the phosphorylation of IKK-alpha on Ser-176 by NIK may be required for cytokine-mediated NF-kappaB activation.
Amino Acid Sequence↗
Alkyl esters of camptothecin and 9-nitrocamptothecin: synthesis, in vitro pharmacokinetics, toxicity, and antitumor activity.
Eleven camptothecin esters, 6a-e and 7a-f, were prepared by straightforward acylation of camptothecins with the corresponding acylating reagents such as organic anhydrides and carboxylic acid chlorides. The in vitro pharmacokinetic determination of lactone levels of esters 6a and 7b showed that the biological life span of their lactone forms in human and mouse plasma significantly increased when compared with their mother compounds, camptothecin (3) and 9-nitrocamptothecin (4). The differences of lactone levels between human plasma and mouse plasma for 6a and 7b were much smaller than what was observed for their mother compounds. The in vivo antitumor activity and toxicity studies demonstrated that some of these esters were very active against human tumor xenografts in nude mice and had an exceptional lack of toxicity in nude mice, even at enormous doses.
Acylation↗
W474C amino acid substitution affects early processing of the alpha-subunit of beta-hexosaminidase A and is associated with subacute G(M2) gangliosidosis.
Mutations in the HEXA gene, encoding the alpha-subunit of beta-hexosaminidase A (Hex A), that abolish Hex A enzyme activity cause Tay-Sachs disease (TSD), the fatal infantile form of G(M2) gangliosidosis, Type 1. Less severe, subacute (juvenile-onset) and chronic (adult-onset) variants are characterized by a broad spectrum of clinical manifestations and are associated with residual levels of Hex A enzyme activity. We identified a 1422 G-->C (amino acid W474C) substitution in the first position of exon 13 of HEXA of a non-Jewish proband who manifested a subacute variant of G(M2) gangliosidosis. On the second maternally inherited allele, we identified the common infantile disease-causing 4-bp insertion, +TATC 1278, in exon 11. Pulse-chase analysis using proband fibroblasts revealed that the W474C-containing alpha-subunit precursor was normally synthesized, but not phosphorylated or secreted, and the mature lysosomal alpha-subunit was not detected. When the W474C-containing alpha-subunit was transiently co-expressed with the beta-subunit to produce Hex A (alphabeta) in COS-7 cells, the mature alpha-subunit was present, but its level was much lower than that from normal alpha-subunit transfections, although higher than in those cells transfected with an alpha-subunit associated with infantile TSD. Furthermore, the precursor level of the W474C alpha-subunit was found to accumulate in comparison to the normal alpha-subunit precursor levels. We conclude that the 1422 G-->C mutation is the cause of Hex A enzyme deficiency in the proband. The resulting W474C substitution clearly interferes with alpha-subunit processing, but because the base substitution falls at the first position of exon 13, aberrant splicing may also contribute to Hex A deficiency in this proband.
Adolescent↗
Characterization of HetR protein turnover in Anabaena sp. PCC 7120.
The hetR gene plays an important role in heterocyst development and pattern formation in heterocystous cyanobacteria. The hetR gene from Anabaena sp. PCC 7120 was overexpressed in Escherichia coli. Antibodies raised against the recombinant HetR protein (rHetR) were used to characterize metabolism of the HetR of Anabaena sp. PCC 7120 in vivo. HetR was present at a low level when Anabaena sp. PCC 7120 was grown in the presence of combined nitrogen. Shifting from nitrogen repletion conditions to nitrogen depletion conditions led to a two fold increase of HetR in total cell extracts, and most of HetR was located in heterocysts. The amount of HetR in total cellular extracts increased rapidly after shifting to nitrogen depletion conditions and reached a maximum level 3 h after the shift. Isoelectrofocusing electrophoresis revealed that the native HetR had a more acidic isoelectric point than did rHetR. After combined nitrogen was added to the nitrogen-depleted cultures, the degradation of HetR depended on culture conditions: before heterocysts were fully developed, HetR was rapidly degraded; after heterocysts were fully developed, HetR was degraded much more slowly. The distribution of HetR in other species of cyanobacteria was also studied.
Amino Acid Sequence↗