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2.  Chemical pattern on silica surface prepared by UV irradiation of 3-mercaptopropyltriethoxy silane layer: surface characterization and fibrinogen adsorption 
A flat silica surface modified with 3-mercaptopropyltriethoxy silane (MTS) was patterned using UV irradiation and a custom-designed mask. The irradiated surface was characterized by X-ray photoelectron spectroscopy (XPS), scanning force microscopy (SFM) and water contact angle measurements. The XPS S2p spectra indicated that the UV treatment resulted in the oxidation of MTS sulfur. The optimal UV irradiation dose for patterning, estimated from the XPS S2p binding energy shifts and water contact angles of irradiated surfaces, was 4.8 J cm−2 at 270 nm. The surface patterns were visualized by total internal reflection fluorescence microscopy, while exposing the pattern to a solution of acridine orange, by water vapor condensation, and by SFM lateral force imaging in dilute electrolyte solution. The adhesion SFM measurements revealed the adhesion force only on the areas which were not UV-irradiated. The adsorption of fluorescein-labeled fibrinogen (FITC-Fgn) from dilute buffer solution also produced visual information on the pattern. The kinetics of FITC-Fgn adsorption onto the oxidized and unoxidized MTS-silica surfaces from dilute protein solution proceeded with identical initial adsorption rates. The steady-state FITC-Fgn adsorption was twice as large on the unoxidized MTS-silica than on the oxidized MTS-silica surface.
doi:10.1016/S0927-7765(96)01298-2
PMCID: PMC4131241  PMID: 25132726
Fibrinogen adsorption; 3-Mercaptopropyltriethoxy silane; Modified silica; Scanning force microscopy; Total internal reflection fluorescence microscopy
3.  Rolling Circle DNA Synthesis: Small Circular Oligonucleotides as Efficient Templates for DNA Polymerases 
We report that small, single-stranded circular DNA oligonucleotides 26 to 74 nucleotides (nt) in size can behave as catalytic templates for DNA synthesis by several DNA polymerase enzymes. The DNA products are repeating end-to-end multimeric copies of the synthetic circular DNAs, and range from 1 000 to > 12 000 nucleotides in length. Several aspects of this reaction are unusual: first, the synthesis proceeds efficiently despite the curvature and small size of the circles, some of which have diameters significantly smaller than that of the enzyme itself. Second, the synthesis can proceed hundreds of times around the circle, while rolling replication of larger circular plasmid DNAs requires other proteins for processive synthesis. Finally, the synthesis scheme produces multiple copies of the template without the requirement for either heating or cooling cycles and requires less than stoichiometric amounts of primer, unlike other DNA synthesis methods. We report on the scope of this reaction, and demonstrate that the multimeric products can be cleaved enzymatically to short, sequence-defined oligodeoxynucleotides. This new approach to DNA synthesis may be a practical way to produce useful repeating DNAs, and combined with DNA cleavage strategies, it may represent a useful enzymatic approach to short, sequence-defined oligodeoxynucleotides.
doi:10.1021/ja952786k
PMCID: PMC2935701  PMID: 20830216
4.  Analysis of genomic instability in Li-Fraumeni fibroblasts with germline p53 mutations 
Oncogene  1996;12(11):2267-2278.
Germline p53 mutations are frequently observed in the normal DNA of cancer-prone patients with Li-Fraumeni syndrome (LFS). Fibroblasts from LFS patients develop chromosomal aberrations, loss of cell cycle control, and spontaneous immortalization. We transfected four different mutant p53 genes into human skin fibroblasts from normal donors with two copies of wild-type p53 (p53wt/wt). Each mutant p53 expression-plasmid induced genomic instability equivalent to that seen in LFS cells. To test the role of wild-type and mutant p53 alleles in DNA replication and fidelity in LFS cells, we analysed the replication of the SV40-based shuttle vector pZ189 in four types of cells. We used p53wt/mut and p53mut/− LFS fibroblasts, and p53−/− non-LFS cells. Replication of pZ189 in vivo was significantly reduced by the presence of a p53wt allele. To show that this was not just due to inhibition of the function of T-antigen in SV40-based replication, we constructed a shuttle vector, pZ402, that contains a mutation in SV40 T-antigen which blocks its ability to interact with p53. Replication of pZ402 in LFS cells was also reduced by the presence of p53wt, indicating that p53 can inhibit replication by interacting with proteins within the cellular replication machinery. Replicative errors in this shuttle vector are detected as mutations in a marker gene, supF. In addition to supF mutations, we observed deletion of a portion of the SV40 T-antigen gene in 100% of replicated plasmid pZ189 mutants (supF−) from the p53wt/mut fibroblasts and in 88% of the supF− mutants from the p53mut/− (amino acid 175 arg to his) LFS cells. In one cell strain of immortal LFS cells, p53mut/−, containing a p53 frameshift mutation at amino acid 184, pZ189 replication yielded very few of these deleted shuttle vector plasmids (15%). These large deletions were not detected in plasmids replicated in p53−/− non-LFS cells, Saos-2 cells. Replicated plasmids with a normal supF gene were never found to have this large deletion regardless of the cell from which they were derived. Because the supF gene is not in the same region of the shuttle vector as the T-antigen gene it appears that second, independent gene deletions are frequent when replicative errors in supF occur in cells with a mutant p53. We conclude, therefore, that p53wt/mut LFS cells contain an activity that promotes mutations. Such an activity, which is likely to be due to the p53mut, could result in the high rate of chromosomal instability and allelic loss of the wild-type p53 observed as these cells spontaneously immortalize.
PMCID: PMC2719722  PMID: 8649766
tumor suppressor gene; germline mutations; chromosome instability; shuttle vector mutagenesis; DNA replication
5.  Damage, Repair, and Mutagenesis in Nuclear Genes after Mouse Forebrain Ischemia–Reperfusion 
To determine whether oxidative stress after cerebral ischemia–reperfusion affects genetic stability in the brain, we studied mutagenesis after forebrain ischemia–reperfusion in Big Blue transgenic mice (male C57BL/6 strain) containing a reporter lacI gene, which allows detection of mutation frequency. The frequency of mutation in this reporter lacI gene increased from 1.5 to 7.7 (per 100,000) in cortical DNA after 30 min of forebrain ischemia and 8 hr of reperfusion and remained elevated at 24 hr reperfusion. Eight DNA lesions that are characteristic of DNA damage mediated by free radicals were detected. Four mutagenic lesions (2,6-diamino-4-hydroxy-5-formamidopyrimidine, 8-hydroxyadenine, 5-hydroxycytosine, and 8-hydroxyguanine) examined by gas chromatography/mass spectrometry and one corresponding 8-hydroxy-2′-deoxyguanosine by a method of HPLC with electrochemical detection increased in cortical DNA two- to fourfold (p < 0.05) during 10–20 min of reperfusion. The damage to γ-actin and DNA polymerase-β genes was detected within 20 min of reperfusion based on the presence of formamidopyrimidine DNA N-glycosylase-sensitive sites. These genes became resistant to the glycosylase within 4–6 hr of reperfusion, suggesting a reduction in DNA damage and presence of DNA repair in nuclear genes. These results suggest that nuclear genes could be targets of free radicals.
PMCID: PMC2711221  PMID: 8824320
apoptosis; brain; mutation; dementia; oxidative stress; stroke
6.  Pulse therapy with cyclophosphamide and methylprednisolone in patients with moderate to severe paraquat poisoning: a preliminary report. 
Thorax  1996;51(7):661-663.
BACKGROUND: Severe paraquat poisoning causes considerable morbidity and mortality. High doses of cyclophosphamide and dexamethasone have been used to treat patients with paraquat poisoning, but with mixed results. The use of pulse methylprednisolone and cyclophosphamide was investigated in the treatment of moderately severe paraquat poisoning. METHODS: During a six-year period 87 patients with paraquat poisoning were admitted to hospital, of whom 33 had moderate to severe intoxication. Seventeen patients received conventional treatment and served as historical controls, and 16 received intravenous infusions of cyclophosphamide 1 g daily for two days and methylprednisolone 1 g daily for three days. RESULTS: There were no differences between the groups in age, sex, severity of paraquat poisoning (as assessed by urine dithionite tests), or in the time elapsed from ingestion to presentation at hospital or to the beginning of haemoperfusion. No differences were seen in biochemical measurements on the third day after paraquat poisoning. The mortality in the pulse therapy group was lower than that in the control group (4/16 (25%) versus 12/17 (70.6%), p = 0.01). All fatalities were from progressive respiratory failure. CONCLUSIONS: Pulse therapy with cyclophosphamide and methylprednisolone may be effective in preventing respiratory failure and reducing mortality in patients with moderate to severe paraquat poisoning. Further controlled studies are needed to confirm this and to establish the mechanisms.
PMCID: PMC472485  PMID: 8882069
7.  The Involvement of Interleukin (IL)-15 in Regulating the Differentiation of Granulated Metrial Gland Cells in Mouse Pregnant Uterus 
The Journal of Experimental Medicine  1996;184(6):2405-2410.
Previous studies have suggested that granulated metrial gland (GMG) cells are bone marrow– derived lymphoid cells, which differentiate in situ in the mouse pregnant uterus into natural killer (NK)–like cells. Similar to NK cells, GMG cells express an abundant level of cytolytic mediators such as perforin. The factor(s) regulating the differentiation of GMG cells remain(s) to be identified, although cytokines previously implicated in the stimulation/activation of NK cells (e.g., IL-2, IL-6, IL-7, and IL-12) can be considered as potential candidates. Recently, IL-15, a novel cytokine, which displays biological activities similar to IL-2, has also been shown to be capable of activating NK cells. Using reverse transcription–polymerase chain reaction (RT-PCR) analysis, we have demonstrated in the present study that IL-15 and its cognate receptor, but not the other cytokines, are expressed in the mouse pregnant uterus, with a time course concomitant with those of cytolytic mediators in differentiated GMG cells. Moreover, IL-15, though not IL-2, is capable of inducing the expression of perforin and granzymes in pregnant uterine tissues explanted in vitro. Data obtained from in situ hybridization study have suggested that the macrophages present in the pregnant uterus may be responsible for the production of IL-15. These results suggest that IL-15 is involved in regulating the differentiation of GMG cells during mouse pregnancy.
PMCID: PMC2196382  PMID: 8976195
8.  Tumor necrosis factor alpha and interleukin-12 contribute to resistance to the intracellular bacterium Brucella abortus by different mechanisms. 
Infection and Immunity  1996;64(7):2782-2786.
Both interleukin-12 (IL-12) and tumor necrosis factor alpha (TNF-alpha) are produced early in intracellular bacterial infection. Depletion of either IL-12 or TNF-alpha by a single injection of specific antibody 4 h before the injection of Brucella abortus 19 led to the exacerbation of infection 2 weeks later. Whereas the effect of IL-12 depletion on resistance was persistent and exacerbation was still significant 6 weeks later, the bacterial numbers in mice depleted of TNF-alpha were similar to the bacterial numbers in control infected mice by 6 weeks postinfection. Massive splenomegaly, which is often seen in 2-week Brucella-infected mice, was not observed in IL-12- or TNF-alpha-depleted mice. Both IL-12- and TNF-alpha-depleted mice showed reduced cell accumulation in the spleen compared with the massive cell accumulation in control infected mice. Granuloma formation in livers was much reduced in IL-12-depleted mice but not in TNF-alpha-depleted mice. Gamma interferon (IFN-gamma) production by cells from TNF-alpha-depleted mice was not significantly different from that of cells from control infected mice. In contrast, the production of IFN-gamma by both CD4+ and CD8+ T cells from IL-12-depleted mice was greatly reduced, compared with that from control infected mice. This effect was still observed when the antibody injection was delayed for up to 7 days postinfection, but injections of anti-IL-12 antibody into mice with established Brucella infection had no significant effect on IFN-gamma production by T cells. Taken together, these results suggested that IL-12 contributed to resistance mainly via an IFN-gamma-dependent pathway and had a profound effect on the induction of acquired cellular resistance. In contrast, TNF-alpha was involved in resistance possibly via direct action on effector cells and may not be essential for the induction of acquired cellular resistance.
PMCID: PMC174139  PMID: 8698508
9.  Comparisons of blood pressure between Asian-American children and children from other racial groups in Chicago. 
Public Health Reports  1996;111(Suppl 2):65-67.
RESEARCHERS COMPARED AVERAGE BLOOD PRESSURE, prevalence of elevated blood pressure, and average anthropometric measurements of Asian children with those same measures in children from other racial and ethnic groups, including blacks, whites, and Hispanics. The sample consisted of 1318 boys and 1548 girls ages 6 to 9 who had complete blood pressure and anthropometric data, which were derived from a health screening program in nonpublic schools conducted by the Chicago Department of Health from 1975 to 1978. The systolic pressure, adjusted for age, weight, and height, for Asian, black, Hispanic, and white boys was 108.1, 105.8, 104.7, and 105.6 mmHg, and for diastolic pressure, the adjusted values were 59.6, 58.9, 56.3, and 57.4 mmHg. For both systolic and diastolic, the differences between Asian boys and white boys and between Asian boys and Hispanic boys were statistically significant. For girls, the results were similar. In addition, for boys, the prevalence rates of elevated blood pressure (systolic greater than or equal to 122 mmHg or diastolic greater than or equal to 78 mmHg) were similar among the four groups. For girls, the prevalence rate for Asians was higher than those in the other groups; however, the differences were not statistically significant. Since hypertension is a major health problem in Asians, it is important to confirm these findings and to understand why mean blood pressure adjusted for age and body size is higher in Asian children than in other racial groups.
PMCID: PMC1381671  PMID: 8898780
10.  Allelic imbalance on chromosome 5q predicts long-term survival in neuroblastoma. 
British Journal of Cancer  1996;74(12):1855-1861.
Neuroblastoma is the most common extracranial solid tumour of childhood. Amplification of the proto-oncogene, N-myc, confers a poor prognosis in neuroblastoma, while hyperdiploidy is associated with a favourable outcome. Little is known about the contribution of tumour-suppressor genes to the development or progression of neuroblastoma. We examined allelic imbalance at the locus of the tumour-suppressor gene, APC (adenomatous polyposis coli), on chromosome 5q using a polymerase chain reaction (PCR)-based assay. Nine of 24 (37.5%) informative neuroblastoma tumours showed allelic imbalance (AI) at this locus. Clinical data concerning N-myc amplification and DNA content were correlated with these results in the same patients. Allelic imbalance was found only in tumours containing a single copy of the N-myc gene and exhibiting hyperdiploidy. All nine patients with AI of chromosome 5q were alive after a median follow-up period of 46 months, while 7 of 15 (47%) of those lacking AI at this locus had died (P = 0.018). Allelic imbalance at three additional loci on chromosome 5 was demonstrated in tumours that exhibited AI at the APC locus, suggesting that endoreduplication of chromosome 5 had occurred. Fluorescent in situ hybridisation (FISH) analysis of tumour tissue from one patient exhibiting AI demonstrated two, three, four or six copies of the APC gene per cell, consistent with this hypothesis. These data suggest that allelic imbalance of chromosome 5 is involved in at least a subset of neuroblastomas and influences survival in patients with neuroblastoma.
Images
PMCID: PMC2074823  PMID: 8980382
11.  The relationship of fluorosis and brick tea drinking in Chinese Tibetans. 
Cao, J | Bai, X | Zhao, Y | Liu, J | Zhou, D | Fang, S | Jia, M | Wu, J
Environmental Health Perspectives  1996;104(12):1340-1343.
Brick tea-drinking fluorosis is an unusual environmental problem. As a result of an investigation of tea-drinking habits, total fluoride intakes, dental fluorosis, and skeletal fluorosis, this disease has been found in the Sichuan Province of China in Tibetans with a long history of drinking brick tea. The dental fluorosis investigation of 375 Tibetan children (213 males, 162 females) and 161 Han children (86 males, 75 females), 8-15 years of age, was carried out in Daofu County, Sichuan Province. According to the standard of the Chinese Health Ministry, a skeletal fluorosis survey of 658 Tibetans (264 males, 394 females) and 41 Hans (20 males, 11 females), all over 16 years old, was performed. The total fluoride intake and fluorosis were determined from a question--calculation method in all participants. The morbidities of dental fluorosis in Tibetan and Han children are 51.2% and 11.05%, respectively, and the indexes of dental fluorosis are 1.33 and 0.17 (chi 2 = 75.7, p < 0.01) respectively. The morbidity of skeletal fluorosis is 32.83% for Tibetan children and zero for the Han children. The fluoride intakes of Tibetan children and adults were 5.49 mg/person/day and 10.43 mg/person/day, respectively, in this area. Of total everyday fluoride intake, 94.2% by children and 94.4% by adults was from brick tea and zanba (r = 0.99).
PMCID: PMC1469557  PMID: 9118877
13.  Comparison of the Roche AMPLICOR MYCOBACTERIUM assay and Digene SHARP Signal System with in-house PCR and culture for detection of Mycobacterium tuberculosis in respiratory specimens. 
Journal of Clinical Microbiology  1996;34(12):3092-3096.
Two commercial primer kits and detection systems, the Roche AMPLICOR MYCOBACTERIUM test and the Digene primer-probe kit with the SHARP Signal System, were compared to in-house PCR as well as standard culture techniques. For the 27 culture-positive specimens, the Roche AMPLICOR MYCOBACTERIUM test detected 20 specimens, the Digene system detected 19, and in-house PCR detected 21. Of the 86 culture-negative specimens, 13 were positive by the Roche AMPLICOR MYCOBACTERIUM test, 16 were positive by the Digene system, and 21 were positive by in-house PCR. When clinical situations were evaluated, 11 of 13 culture-negative Roche AMPLICOR MYCOBACTERIUM test-positive specimens, 10 of 16 culture-negative Digene system-positive specimens, and 13 of 21 culture-negative-in-house PCR-positive specimens were diagnosed as true-positive specimens. The sensitivities of Roche AMPLICOR MYCOBACTERIUM test, the Digene system, and in-house PCR were 73.81, 69.05, and 80.95%, and the specificities were 97.18, 91.55 and 88.73%, respectively. The positive predictive values were 93.94, 82.86, and 80.95%, and the negative predictive values were 86.25, 83.33, and 88.73%, respectively. For the commercial kits, the Roche AMPLICOR MYCOBACTERIUM test seems to be more sensitive and specific than the Digene system. However, the Roche AMPLICOR MYCOBACTERIUM test cannot be used on nonrespiratory specimens.
PMCID: PMC229464  PMID: 8940453
14.  D-glucose-induced dysmorphogenesis of embryonic kidney. 
Journal of Clinical Investigation  1996;98(11):2478-2488.
An organ culture system was used to study the effect of D-glucose on embryonic kidneys, and to delineate the mechanism(s) relevant to their dysmorphogenesis. Metanephroi were cultured in the presence of 30 mM D-glucose. A notable reduction in the size and population of nephrons was observed. Ureteric bud branches were rudimentary and the acuteness of their tips, the site of nascent nephron formation, was lost. Metanephric mesenchyme was atrophic, had reduced cell replication, and contained numerous apoptotic cells. Competitive reverse transcriptase-PCR analyses and immunoprecipitation studies indicated a decrease in expression of heparan sulfate proteoglycan (perlecan). Status of activated protein-2 was evaluated since its binding motifs are present in the promoter region of the perlecan gene. Decreased binding activity of activated protein-2, related to its phosphorylation, was observed. D-glucose-treated explants also had reduced levels of cellular ATP. Exogenous administration of ATP restored the altered metanephric morphology and reduced [35S]sulfate-incorporated radioactivity associated with perlecan. The data suggest that D-glucose adversely affects the metanephrogenesis by perturbing various cellular phosphorylation events involved in the transcriptional and translational regulation of perlecan. Since perlecan modulates epithelial/mesenchymal interactions, its deficiency may have led to the metanephric dysmorphogenesis and consequential atrophy of the mesenchyme exhibiting accelerated apoptosis.
PMCID: PMC507705  PMID: 8958210
15.  Photodynamic therapy using intravenous delta-aminolaevulinic acid-induced protoporphyrin IX sensitisation in experimental hepatic tumours in rats. 
British Journal of Cancer  1996;74(10):1526-1533.
The efficacy of photodynamic therapy (PDT) using delta-aminolaevulinic acid (ALA)-induced protoporphyrin IX (PpIX) sensitisation and laser light at 635 nm was investigated in the treatment of experimental hepatic tumours. The model of liver tumours was induced either by local inoculation or by administration of tumour cells through the portal vein in rats. ALA at a dose of 60 mg kg(-1) b.w. was intravenously administered 60 min before PDT. PpIX accumulation in tumour, normal liver and abdominal wall muscle was detected by means of laser-induced fluorescence (LIF). Laser Doppler imaging (LDI) was used to determine changes in the superficial blood flow in connection with PDT. Histopathological examinations were performed to evaluate the PDT effects on the tumour and the surrounding liver tissue, including pathological features in the microvascular system. The accumulation of PpIX, as monitored by LIF, showed high fluorescence intensities at about 635 nm in both the hepatic tumour tissue and normal liver and low values in the abdominal wall. LDI demonstrated that the blood flow in the treated tumour and its surrounding normal liver tissue decreased immediately after the PDT, indicating an effect on the vascular system. A large number of thrombi in the irradiated tumour were found microscopically 3 h after the PDT. The tumour growth rate showed a marked decrease when evaluated 3 and 6 days after the treatment. These results show that the ALA-PDT is effective in the inhibition of growth of experimental hepatic tumours.
Images
PMCID: PMC2074833  PMID: 8932330
16.  Epidemiological typing of isolates from an outbreak of infection with multidrug-resistant Enterobacter cloacae by repetitive extragenic palindromic unit b1-primed PCR and pulsed-field gel electrophoresis. 
Journal of Clinical Microbiology  1996;34(11):2784-2790.
An outbreak of multidrug-resistant Enterobacter cloacae infection lasted for 4 months in a neonatal intensive care unit (NICU). Forty-six isolates from the NICU and 20 epidemiologically unrelated strains were characterized by pulsed-field gel electrophoresis (PFGE) and repetitive extragenic palindromic unit b1-primed PCR (REPUb1-PCR) typing. The PFGE patterns after XbaI restriction of the bacterial DNA were analyzed by computer software (Gelcompar) using the UPGMA (unweighted pair group method with arithmetic averages) clustering method and the Dice coefficient. The 46 isolates from the NICU were classified by PFGE typing into five clusters: A (further classified into 7 subtypes, A1 to A7), B, C, D, and E. This outbreak was attributed to multiple genetically related strains of cluster A which had a similarity of 85.8% +/- 4.6%. The minor band differences among strains of cluster A were probably due to minor genetic mutations. The type A1 and A3 strains were isolated from the clinical specimens of patients and hands of nurses. It was probable that these outbreak strains were transmitted among patients via the hands of personnel. REPUb1-PCR typing of the 46 isolates also demonstrated five types, in agreement with results obtained by the PFGE technique, but could not detect the minor mutations among the cluster A strains. Twenty epidemiologically unrelated strains were well distinguished by both PFGE and REPUb1-PCR typing. We conclude that PFGE is a highly discriminatory but time-consuming method for epidemiological typing of E. cloacae and that REPUb1-PCR is a more rapid method with good reproducibility and discriminatory power comparable to that of PFGE.
PMCID: PMC229404  PMID: 8897183
17.  Basal phosphorylation of the PEST domain in the I(kappa)B(beta) regulates its functional interaction with the c-rel proto-oncogene product. 
Molecular and Cellular Biology  1996;16(11):5974-5984.
The product of the c-rel proto-oncogene (c-Rel) belongs to the NF-kappaB/Rel family of polypeptides and has been implicated in the transcriptional control of cell proliferation and immune function. In human T lymphocytes, c-Rel is sequestered in the cytoplasmic compartment by constitutively phosphorylated inhibitors, including I(kappa)B(alpha) and I(kappa)B(beta). Studies with bacterially expressed forms of these inhibitory proteins revealed that unphosphorylated I(kappa)B(alpha) but not I(kappa)B(beta) assembles with c-Rel and inhibits its DNA binding activity. Furthermore, latent I(kappa)B(beta)-c-Rel complexes derived from mammalian cells were sensitive to phosphatase treatment, whereas I(kappa)B(alpha)-c-Rel complexes were resistant. We have identified a constitutive protein kinase in unstimulated T cells that associates with and phosphorylates I(kappa)B(beta) in vitro. The substrate specificity, electrophoretic mobility, and antigenic properties of this I(kappa)B(beta)-associated kinase (BAK) suggest identity with casein kinase II (CKII), an enzyme known to mediate basal phosphorylation of I(kappa)B(alpha). Phosphorylation of recombinant I(kappa)B(beta) by either BAK or CKII restored the capacity of this inhibitor to antagonize the DNA binding activity of c-Rel. Peptide mapping and mutational analyses localized the bulk of the basal phosphorylation sites in I(kappa)B(beta) to the C-terminal PEST domain, which contains two potential acceptors for CKII-mediated phosphoryl group transfer (Ser-313 and Ser-315). Point mutations introduced into the full-length inhibitor at Ser-313 and Ser-315 led to a significant reduction in the phosphorylation of I(kappa)B(beta) and severely impaired its c-Rel inhibitory function in vivo. Taken together, these findings strongly suggest that basal phosphorylation of the PEST domain of I(kappa)B(beta) at consensus CKII sites is required for the efficient formation of latent I(kappa)B(beta)-c-Rel complexes.
PMCID: PMC231600  PMID: 8887627
18.  F(c)gammaRI-targeted fusion proteins result in efficient presentation by human monocytes of antigenic and antagonist T cell epitopes. 
Journal of Clinical Investigation  1996;98(9):2001-2007.
A major challenge for using native or modified T cell epitopes to induce or suppress immunity relates to poor localization of peptides to antigen presenting cells (APCs) in vivo. In this study, we demonstrate enhanced presentation of antigenic and antagonistic peptides by targeting them to the type I Fc receptor for IgG (F(c)gammaRI, CD64) on human monocytes. A Th epitope of tetanus toxoid, TT830, and the antagonistic peptide for TT830, TT833S, were genetically grafted into the constant region of the heavy chain of the humanized anti-CD64 mAb 22 and expressed as monovalent fusion proteins, Fab22-TT830 and Fab22-TT833S. These CD64-targeted peptides were up to 1,000- and 100-fold more efficient than the parent peptides for T cell stimulation and antagonism, respectively, suggesting that such fusion proteins could effectively increase the delivery of peptides to APCs in vivo. Moreover, the F(c)gammaRI-targeted antagonistic peptide inhibited proliferation of TT830-specific T cells even when APCs were first pulsed with native peptide, a situation comparable with that which would be encountered in vivo when attempting to ameliorate an autoimmune response. These data suggest that targeted presentation of antagonistic peptides could lead to promising Ag-specific therapies for T cell-mediated autoimmune diseases.
PMCID: PMC507643  PMID: 8903318
19.  Secondary structure content of the HDV ribozyme in 95% formamide. 
Nucleic Acids Research  1996;24(20):3911-3917.
The Hepatitis Delta Virus (HDV) ribozyme self-cleaving activity in 20 M formamide solutions is unique. Does this catalytic activity result from the conservation of its tertiary structure in 20 M formamide? We followed the ribozyme structure in formamide solutions by monitoring the amount of bound Ethidium Bromide (EB). We were able to measure the quantity of dye bound using time-resolved fluorescence spectroscopy, as an estimate of the ribozyme double helical content. This method, calibrated by using oligonucleotides with defined tertiary structure and denaturing solvents, parallels NMR and UV measurements as a function of temperature. Measurements with the HDV ribozyme lead to three conclusions: (a) both the precursor and product RNAs are structured to 24 M (95% w/w) formamide or 4 M H2O solutions which is equivalent to 4 M H2O; (b) the HDV ribozyme is the only RNA sequence investigated in this study that retains so much structure in formamide; and (c) DNA analogs of formamide resistant HDV ribozyme sequences lose their structure at less than 15 M formamide. Thus, the structural integrity of the HDV ribozyme is an intrinsic property of the RNA molecule and its sequence.
PMCID: PMC146184  PMID: 8918791
20.  Genomic structure and expression of the murine Hmgi-c gene. 
Nucleic Acids Research  1996;24(20):4071-4077.
The murine Hmgi-c gene, a member of the Hmgi gene family, contains five exons encompassing >110 kb of genomic DNA at the pygmy locus on mouse chromosome 10. Northern analysis identified a 4.1 kb transcript which contains a 324 bp open reading frame encoding a 12 kDa HMGI-C protein. Further analysis defined both the 5' and 3' untranslated regions of the Hmgi-c mRNA species as 658 and 2967 bp respectively. The HMGI-C protein has three consecutive AT hook DNA binding domains and an acidic domain, each of which are encoded by individual exons; such an organization is conserved among the HMGI gene family members from insects to mammals. Similar to the HMGI/Y proteins, the HMGI-C protein does not function as a typical transcriptional activator. Developmental studies revealed that the Hmgi-c gene is expressed predominantly during mouse embryogenesis. Since the human homolog is disrupted in a number of tumors, HMGI-C could play an important role in cell proliferation and differentiation during mammalian development.
PMCID: PMC146186  PMID: 8918814
21.  Purification and cloning of a thermostable xylose (glucose) isomerase with an acidic pH optimum from Thermoanaerobacterium strain JW/SL-YS 489. 
Journal of Bacteriology  1996;178(20):5938-5945.
An unusual xylose isomerase produced by Thermoanaerobacterium strain JW/SL-YS 489 was purified 28-fold to gel electrophoretic homogeneity, and the biochemical properties were determined. Its pH optimum distinguishes this enzyme from all other previously described xylose isomerases. The purified enzyme had maximal activity at pH 6.4 (60 degrees C) or pH 6.8 (80 degrees C) in a 30-min assay, an isoelectric point at 4.7, and an estimated native molecular mass of 200 kDa, with four identical subunits of 50 kDa. Like other xylose isomerases, this enzyme required Mn2+, Co2+, or Mg2+ for thermal stability (stable for 1 h at 82 degrees C in the absence of substrate) and isomerase activity, and it preferred xylose as a substrate. The gene encoding the xylose isomerase was cloned and expressed in Escherichia coli, and the complete nucleotide sequence was determined. Analysis of the sequence revealed an open reading frame of 1,317 bp that encoded a protein of 439 amino acid residues with a calculated molecular mass of 50 kDa. The biochemical properties of the cloned enzyme were the same as those of the native enzyme. Comparison of the deduced amino acid sequence with sequences of other xylose isomerases in the database showed that the enzyme had 98% homology with a xylose isomerase from a closely related bacterium, Thermoanaerobacterium saccharolyticum B6A-RI. In fact, only seven amino acid differences were detected between the two sequences, and the biochemical properties of the two enzymes, except for the pH optimum, are quite similar. Both enzymes had a temperature optimum at 80 degrees C, very similar isoelectric points (pH 4.7 for strain JW/SL-YS 489 and pH 4.8 for T. saccharolyticum B6A-RI), and slightly different thermostabilities (stable for 1 h at 80 and 85 degrees C, respectively). The obvious difference was the pH optimum (6.4 to 6.8 and 7.0 to 7.5, respectively). The fact that the pH optimum of the enzyme from strain JW/SL-YS 489 was the property that differed significantly from the T. saccharolyticum B6A-RI xylose isomerase suggested that one or more of the observed amino acid changes was responsible for this observed difference.
PMCID: PMC178450  PMID: 8830690
22.  Deletion of the carboxyl-terminal transactivation domain of MGF-Stat5 results in sustained DNA binding and a dominant negative phenotype. 
Molecular and Cellular Biology  1996;16(10):5691-5700.
The Stat (signal transducer and activator of transcription) factors transmit cytokine, growth factor, and hormone responses. Seven members of the Stat gene family are known. MGF-Stat5a has been discovered as a mediator of the prolactin response in mammary epithelial cells. Two closely related variants of Stat5, Stat5a and Stat5b, are encoded by distinct genes. We examined the functional properties of the carboxyl termini of these molecules. Wild-type Stat5a (794 amino acids) and the carboxyl-terminal deletion mutant Stat5a delta 772 supported prolactin-induced transcription of a beta-casein promoter-reporter construct in COS7 cells; Stat5a delta 750 did not. Upon prolactin activation, tyrosine phosphorylation and the specificity of DNA binding were indistinguishable among the three Stat5a variants. Tyrosine dephosphorylation and the downregulation of the DNA-binding activity were delayed in the Stat5a delta 750 mutant. The carboxyl-terminal transactivation domain of Stat5a, amino acids 722 to 794, can be conferred to the DNA-binding domain of the yeast transcription factor GAL4. Coexpression of Stat5a or Stat5b and of the carboxyl-terminal deletion mutants resulted in the suppression of transcriptional induction in COS or Ba/F3 cells. We propose that Stat5a delta 750 and Stat5b delta 754 are lacking functional transactivation domains and exert their dominant negative effects by blocking the DNA-binding site in Stat5-responsive gene promoters.
PMCID: PMC231569  PMID: 8816482
23.  Direct interaction between protein kinase C theta (PKC theta) and 14-3-3 tau in T cells: 14-3-3 overexpression results in inhibition of PKC theta translocation and function. 
Molecular and Cellular Biology  1996;16(10):5782-5791.
Recent studies have documented direct interactions between 14-3-3 proteins and several oncogene and proto-oncogene products involved in signal transduction pathways. Studies on the effects of 14-3-3 proteins on protein kinase C (PKC) activity in vitro have reported conflicting results, and previous attempts to demonstrate a direct association between PKC and 14-3-3 were unsuccessful. Here, we examined potential physical and functional interactions between PKC theta, a Ca(2+)-independent PKC enzyme which is expressed selectively in T lymphocytes, and the 14-3-3 tau isoform in vitro and in intact T cells. PKC theta and 14-3-3 tau coimmunoprecipitated from Jurkat T cells, and recombinant 14-3-3 tau interacted directly with purified PKC theta in vitro. Transient overexpression of 14-3-3 tau suppressed stimulation of the interleukin 2 (IL-2) promoter mediated by cotransfected wild-type or constitutively active PKC theta, as well as by endogenous PKC in ionomycin- and/or phorbol ester-stimulated cells. This did not represent a general inhibition of activation events, since PKC-independent (but Ca(2+)-dependent) activation of an IL-4 promoter element was not inhibited by 14-3-3 tau under similar conditions. Overexpression of wild-type 14-3-3 tau also inhibited phorbol ester-induced PKC theta translocation from the cytosol to the membrane in Jurkat cells, while a membrane-targeted form of 14-3-3 tau caused increased localization of PKC theta in the particulate fraction in unstimulated cells. Membrane-targeted 14-3-3 tau was more effective than wild-type 14-3-3 tau in suppressing PKC theta-dependent IL-2 promoter activity, suggesting that 14-3-3 tau inhibits the function of PKC theta not only by preventing its translocation to the membrane but also by associating with it. The interaction between 14-3-3 and PKC theta may represent an important general mechanism for regulating PKC-dependent signals and, more specifically, PKC theta-mediated functions during T-cell activation.
PMCID: PMC231579  PMID: 8816492
24.  A fluorescence-labeling method for sequencing small RNA on polyacrylamide gel. 
Nucleic Acids Research  1996;24(17):3472-3473.
A practical fluorescence-labeling method for sequencing small RNAs by the traditional 'direct read out' on polyacrylamide gel electrophoresis was established. The 3' terminus of RNA was oxidized into dialdehyde by sodium periodate and then labeled with fluorescein-5-thiosemicarbazide through the condensation reaction between carbazide and aldehyde. The fluorescence-labeled RNA was partially degraded enzymatically and fractionated by polyacrylamide gel electrophoresis. The fluorescent bands were visualised by ultraviolet photography. A partial sequence of yeast 5S rRNA was determined. The result indicates that this method can be used in sequencing small RNAs rapidly, conveniently and safely.
PMCID: PMC146087  PMID: 8811106
25.  A short CIC-2 mRNA transcript is produced by exon skipping. 
Nucleic Acids Research  1996;24(17):3453-3457.
CIC-2 is a voltage- and volume-regulated chloride channel expressed in many tissues. We have shown that CIC-2 in rat lung airways is significantly down-regulated after birth [Murray,C.B. et al. (1995) Am. J. Respir. Cell Mol. Biol., 12, 597-604]. During PCR amplification from rat lung cDNA, a second transcript was identified which is 60 bp shorter than the full length sequence. The peptide translated from this 60 bp sequence contains many positively charged amino acid residues. Rat genomic DNA sequencing showed that the 60 bp sequence is an intact exon. A 71% pyrimidine content and an AAG 3'-end splice site in the intron immediately upstream from the 60 bp sequence were identified which may account for the alternative splicing of the following exon. Human genomic sequence analyses demonstrated similar intron-exon arrangement. A high CT content and an AAG 3' acceptor site were conserved in the intron corresponding to the rat upstream intron. The presence of the full length short form transcript was confirmed in rat kidney by RT-PCR, and the ratio of the long and the short form transcripts varied significantly according to the tissues examined, with the lowest long/short form ratio found in the lung among the tissues studied. Our data demonstrated that the alternatively spliced short form (CIC-2S) is transcribed in many rat tissues, the ratio of the long/short form transcripts is lower in the lung compared with the brain, and the genomic organization in this area is conserved in rat and human.
PMCID: PMC146113  PMID: 8811102

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