Mercury sphygmomanometers: disposal has far reaching consequences.
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Hazardous Substances↗
Biomedical subjects
S Ali
Publications and source records attributed to S Ali.
Multimerization of monocyte chemoattractant protein-1 is not required for glycosaminoglycan-dependent transendothelial chemotaxis.
Chemokines interact with specific G-protein-coupled cell-surface receptors and with glycosaminoglycans (GAGs), such as heparan sulphate. Although chemokines often form multimers in solution, this process may be enhanced following interaction with GAGs on the cell surface, or within the extracellular matrix. However, the significance of multimerization for chemokine function remains controversial. In the present study, a fusion protein was prepared between the prototypical human CC chemokine, monocyte chemoattractant protein-1 (MCP-1; also known as CCL-2) and a large secreted placental alkaline phosphatase (SEAP) moiety. This fusion protein (MCP-1-SEAP) remained monomeric under conditions that promote oligomerization of the native chemokine. Radioligand binding showed that both native MCP-1 and MCP-1-SEAP competed for the same site on the surface of HEK-293 cells expressing the CCR2b chemokine receptor. The interaction between either chemokine species and endothelial cell surface GAGs was antagonized by the addition of the heparan sulphate-like molecule, heparin. Both MCP-1 and MCP-1-SEAP induced a Ca(2+)-flux in the THP-1 monocytic cell line, and were equally effective at promoting transendothelial chemotaxis of mononuclear immune cells, with maximal migration being produced by treatment with 12 nM of either species. In each case this chemotactic response was almost completely antagonized by the addition of heparin. The importance of interaction between either native MCP-1 or MCP-1-SEAP and cell-surface GAGs for transcellular migration was demonstrated by the almost complete absence of leucocyte chemotaxis across monolayers of GAG-deficient mutant cells. In summary, this study shows that multimerization is neither necessary for, nor potentiates, the biological activity of MCP-1. However, the results do clearly demonstrate the importance of the interaction between MCP-1 and cell-surface heparan sulphate for transmonolayer leucocyte chemotaxis.
3T3 Cells↗
Comparison of analytical techniques to quantify malondialdehyde in milk powders.
Several analytical methods were compared to quantify malondialdehyde (MDA) in milk powders. Modified thiobarbituric acid (TBA) methods, using either visible spectrophotometry (direct absorbance reading or after third derivative transformation of the spectrum) or HPLC, required derivatisation at elevated temperature, which appeared to catalyse artefactual MDA formation and thus overestimate the MDA content. In contrast to the TBA derivatisation method, the measurement of MDA as the dinitrophenylhydrazone derivative by HPLC or as the phenylhydrazone product by GC-MS with a deuterated internal standard resulted in lower estimates in the ranges of 2-17- and 3-30-fold, respectively; apparently due to the milder derivatisation conditions. The estimates of MDA determined by both HPLC-UV and GC-MS techniques result in lower values which are similar in magnitude even though the GC-MS technique is more sensitive.
Animals↗
Xanthine oxidase-derived reactive oxygen metabolites contribute to liver necrosis: protection by 4-hydroxypyrazolo[3,4-d]pyrimidine.
Xanthine oxidase (XO) generates reactive oxygen metabolites (ROM) as a by-product while catalyzing their reaction. The present study implicates these ROM in the pathogenesis of liver necrosis produced in rats by the intraperitoneal administration of thioacetamide (TAA; 400 mg/kg b.wt.). After 16 h of TAA administration, the activity of rat liver XO increased significantly compared to that of the control group. At the same time, the level of serum marker enzymes of liver necrosis (aminotransferases and alkaline phosphatase) and tissue malondialdehyde content also increased in TAA treated rats. Tissue malondialdehyde concentration is an indicator of lipid peroxidation and acts as a useful marker of oxidative damage. Pretreatment of rats with XO inhibitor (4-hydroxypyrazolo[3,4-d]pyrimidine; allopurinol (AP)) followed by TAA could lower the hepatotoxin-mediated rise in malondialdehyde level as well as the level of marker enzymes associated with liver necrosis. The survival rate also increased in rats given AP followed by the lethal dose of TAA. In either case, the effect of AP was dose-dependent. Results presented in the paper indicate that increased production of XO-derived ROM contributes to liver necrosis, which can be protected by AP.
Alkaline Phosphatase↗
The p38 MAPK pathway is required for cell growth inhibition of human breast cancer cells in response to activin.
Activin, a member of the TGFbeta family inhibits cell growth in various target tissues. Activin interacts with a complex of two receptors that upon activation phosphorylate specific intracellular mediators, the Smad proteins. The activated Smads interact with diverse DNA binding proteins and co-activators of transcription in a cell-specific manner, thus leading to various activin biological effects. In this study, we investigated the role and mechanism of action of activin in the human breast cancer T47D cells. We found that activin treatment of T47D cells leads to a dramatic decrease in cell growth. Thus activin appears as a potent cell growth inhibitor of these breast cancer cells. We show that activin induces the Smad pathway in these cells but also activates the p38-mitogen-activated protein kinase pathway, further leading to phosphorylation of the transcription factor ATF2. Finally, specific inhibitors of the p38 kinase (SB202190, SB203580, and PD169316) but not an inactive analogue (SB202474) or the MEK-1 inhibitor PD98059 completely abolish the activin-mediated cell growth inhibition of T47D cells. Together, these results define a new role for activin in human breast cancer T47D cells and highlight a new pathway utilized by this growth factor in the mediation of its biological effects in cell growth arrest.
Activins↗
Analysis of estrogen-responsive finger protein expression in benign and malignant human breast.
The estrogen-responsive finger protein (EFP) gene was originally identified in a screen of genomic DNA for genes containing estrogen-response elements (EREs), and its expression was subsequently shown to be estrogen-regulated and correlated with estrogen receptor (ER)alpha-positive tissues in mice. Human chromosomal mapping localized it to 17q23.1, close to BRCA1, in a region frequently lost in breast cancers. Structurally related proteins have been implicated in a variety of important cellular processes, including carcinogenisis. Given that ER is over-expressed in a large proportion of breast cancers, we reasoned that EFP may play a role in mediating the estrogen-dependent progression of breast cancer. We raised anti-sera to EFP and show that EFP is present in the cytoplasm in mammary cell lines and epithelial cells of normal breast tissue. Furthermore, EFP is present in cell culture medium, suggesting that it may be secreted. Immunohistochemistry of paraffin-embedded breast biopsy specimens showed significantly greater levels of EFP in lactating breast and fibroadenomata compared to normal breast (p<0.001 and p = 0.001, respectively), which is likely to be a result of estrogen responsiveness. Levels were reduced in breast cancer (p = 0.02), where no correlation was seen with other immunohistochemical, histopathological or clinical data. The lack of correlation between EFP and ER status of tumors could indicate escape from estrogenic control, pointing to new models of tumor pathogenesis. Increased levels of EFP in lactating breast and the reduction in malignancy suggest a role for EFP in promoting mammary gland differentiation.
Animals↗
Phosphatidylinositol 3-kinase/AKT-mediated activation of estrogen receptor alpha: a new model for anti-estrogen resistance.
Estrogen receptors (ERs) mediate most of the biological effects of estrogen in mammary and uterine epithelial cells by binding to estrogen response elements in the promoter region of target genes or through protein-protein interactions. Anti-estrogens such as tamoxifen inhibit the growth of ER-positive breast cancers by reducing the expression of estrogen-regulated genes. However, anti-estrogen-resistant growth of ER-positive tumors remains a significant clinical problem. Here we show that phosphatidylinositol (PI) 3-kinase and AKT activate ERalpha in the absence of estrogen. Although PI 3-kinase increased the activity of both estrogen-independent activation function 1 (AF-1) and estrogen-dependent activation function 2 (AF-2) of ERalpha, AKT increased the activity of only AF-1. PTEN and a catalytically inactive AKT decreased PI 3-kinase-induced AF-1 activity, suggesting that PI 3-kinase utilizes AKT-dependent and AKT-independent pathways in activating ERalpha. The consensus AKT phosphorylation site Ser-167 of ERalpha is required for phosphorylation and activation by AKT. In addition, LY294002, a specific inhibitor of the PI 3-kinase/AKT pathway, reduced phosphorylation of ERalpha in vivo. Moreover, AKT overexpression led to up-regulation of estrogen-regulated pS2 gene, Bcl-2, and macrophage inhibitory cytokine 1. We demonstrate that AKT protects breast cancer cells from tamoxifen-induced apoptosis. Taken together, these results define a molecular link between activation of the PI 3-kinase/AKT survival pathways, hormone-independent activation of ERalpha, and inhibition of tamoxifen-induced apoptotic regression.
Animals↗
Detection of Y chromosome-specific DNA in the plasma and urine of pregnant women using nested polymerase chain reaction.
The present study was undertaken to evaluate a nested polymerase chain reaction (PCR) for detection of Y chromosome-specific fetal DNA in maternal plasma and urine of pregnant women during different gestational stages. DNA isolated from plasma and urine samples of 80 pregnant women (between 7 and 40 weeks' gestation) underwent amplification for Y chromosome-specific 198 bp DNA by nested PCR. The postpartum analysis of fetal gender showed that 55 women carried male and 25 female fetuses. Among the 55 women bearing male fetuses, Y chromosome-specific signals were detected in 53 (96%) plasma and 21 (38%) urine samples. Moreover, out of 25 women bearing female fetuses, 3 (12%) and 1 (4%) women had Y chromosome-specific signal in plasma and urine, respectively. Analysis of results with respect to gestational age revealed that there was no significant difference in the detection of Y chromosome-specific DNA between different trimesters in maternal plasma of women bearing male fetuses. These results showed that fetus-specific DNA was detected with high sensitivity (96%) and specificity (88%) in the maternal plasma by nested PCR, and therefore the method could be useful as a non-invasive procedure for fetal sex determination and prenatal diagnosis.
Adult↗
Allele loss on chromosome 1p36 in epithelial ovarian cancers.
OBJECTIVES: Prior studies have shown that allelic loss on chromosome 1p36 occurs frequently in ovarian as well as several other types of cancer. This suggests that inactivation of gene(s) in this region may play a role in the pathogenesis of these cancers. The aim of this study was to further delineate the region of loss on chromosome 1p36 in ovarian cancers and to identify associated patient or tumor characteristics. METHODS: Paired normal/cancer DNA samples from 75 ovarian cancers (21 early stage I/II and 54 advanced stage III/IV) were analyzed using microsatellite markers. RESULTS: Forty-nine of 75 (65%) ovarian cancers had loss of at least one marker. The marker demonstrating the most frequent loss was D1S1597, which was lost in 29/57 (51%) informative cases. Allele loss on 1p36 was significantly more common in poorly differentiated ovarian cancers (73%) relative to well or moderately differentiated cases (48%) (P = 0.03). Evidence was obtained for two common regions of deletion: one flanked by D1S1646/D1S244 and another more proximally by D1S244/D1S228. CONCLUSION: These findings further delineate regions on chromosome 1p36 proposed to contain tumor suppressor gene(s) that may play a role in the development and/or progression of epithelial ovarian carcinoma. Allele loss on 1p36 is associated with poor histologic grade.
Alleles↗
Minisatellite associated sequence amplification (MASA) of the hypervariable repeat marker 33.15 reveals a male specific band in humans.
The 16-nt (5' CACCTCTCCACCTGCC 3') consensus sequence of the hypervariable repeat marker 33.15 was used as primer to conduct minisatellite associated sequence amplification (MASA) of human genomic DNA. MASA detected a 513-bp Y chromosome specific band in males as well as a number of variable bands ranging from 260-2700 bp in both the sexes. Overall polymorphism of the variable alleles was low with the band sharing probability of identity being 1.04x10(-4). Cloning and sequence analysis of the male specific band (GenBank accession no. AF134482) showed a high level (60-80%) of sequence homology with several human Y chromosome derived clones. Similar analysis of Indian rhinoceros (Rhinoceros unicornis) genomic DNA showed male specific isomorphic band though of different size. This assay may provide a useful method for the detection of Y chromosome related heterochromatic sequences in human and other vertebrates.
Animals↗
Use of markers of bone turnover for monitoring bone metastases and the response to therapy.
Metastatic bone disease is a frequent complication of breast and other cancers, resulting in skeletal complications that are a significant cause of morbidity and mortality. Bone metastases can be difficult to diagnose radiologically and it can also be difficult to evaluate patients' response to treatment by using the methods that are currently available (radiography, bone scans, and computed axial tomography scans). These are relatively insensitive procedures, thus, there is a requirement for new methods for assessing bone response to ensure patients benefit from the optimum type and duration of treatment. Biochemical markers of bone turnover, such as N-telopeptide and the pyridinium cross-links pyridinoline and deoxypyridinoline, may provide information on bone dynamics that in turn may reflect disease activity in bone. Several studies have shown bone markers to be elevated in cancer patients who have documented evidence of metastatic bone disease. Increased levels are also observed in some patients without clinical evidence of bone metastases, when compared with normal subjects. Rises in such markers may be the first indication of bone involvement and therefore may potentially be useful in early diagnosis of progression. Preliminary data suggest bone marker level correlates with the extent of metastatic disease and the number of skeletal sites involved. Markers of bone turnover may be helpful in identifying those patients likely to respond to bisphosphonate treatment. Such markers are also potentially useful in monitoring the effectiveness of bisphosphonate therapy in the management of bone metastases, in both patients with metastatic breast disease and multiple myeloma.
Amino Acids↗
Estimation of radon concentrations in coal mines using a hybrid technique calibration curve.
The results of epidemiological studies in various countries show that radon and its progeny cause carcinogenic effects on mine workers. Therefore, it becomes of paramount importance to monitor radon concentrations and consequently determine the radon dose rates in coal mines for the protection of coal miners. A new calibration curve was obtained for radon concentration estimation using hybrid techniques. A calibration curve was generated using 226Ra activity concentration measured by a HPGe detector-based gamma-ray spectrometer versus alpha-track-density rate due to radon and its progeny on CR-39 track detector. Using the slope of the experimentally determined curve in the units of Becqueral per kilogram (Bq kg-1) per unit alpha-track-density per hour (cm-2 h-1), radon concentrations (Bq m-3) were estimated using coal samples from various coal mines in two provinces of Pakistan, Punjab and Balochistan. Consequently, radon dose rates were computed in the simulated environment of the coal mines. Results of these computations may be considered with a caveat that the method developed in this paper provides only a screening method to indicate the radon dose in coal mines. It has been shown that the actual measurements of radon concentrations in the coal mines are in agreement with the estimated radon concentrations using the hybrid-technique calibration curve.
Calibration↗
Assessment of a two-generation reproductive and fertility study of mercuric chloride in rats.
Effects of mercuric chloride (MC) on the reproductive performance of two successive generations of rats was evaluated. F(0) rats were exposed to 0.0:0.0 (males:females), 0.50:0.75 (males:females), 1.00:1.50 (males:females) and 1.50:2.50 (males:females) mg/kg/day MC. Selected parental F(1) males and females were exposed to the same doses received by their parents (F(0)). Significant differences resulting from exposure of the F(0) generation to MC were found in implantation efficiency, fertility, live births and day 4 survival indices, litter size, and the body weight of F(1) pups. However, the continued exposure of the F(1) generation to MC did not affect fertility index or litter size, but did significantly affect implantation efficiency, live births and day 4 survival indices. In F(0) males, body weight and weights of the kidneys, testes, epididymides, prostate and seminal vesicles were significantly different, while in F(1) males, body weight, kidney weight, brain weight, liver weight and the weights of the testes, prostate and seminal vesicles were significantly different. In F(0) females, body weight and the weights of the kidneys, brain and liver were significantly different, while in F(1,) females, body weight, as well as the weights of the kidneys, liver, adrenals, uterus and ovaries were significantly different. These data showed that exposure to MC resulted in more adverse reproductive effects in the first generation and that these effects moderated in the second generation.
Animals↗
Prospective association of lipoprotein(a) concentrations and apo(a) size with coronary heart disease among men in the Multiple Risk Factor Intervention Trial.
In this nested case-control study, lipoprotein (a) [Lp(a)] concentrations and apo(a) isoform size were measured in serum samples obtained from men participating in the prospective Multiple Risk Factor Intervention Trial (MRFIT). Serum from men aged 35 to 57 years and stored for up to 20 years were analyzed for Lp(a) levels (n=736) and isoform size (n=487), respectively. Cases involved nonfatal myocardial infarctions (MI; n=98), documented during the active phase of the study that ended on February 28, 1982 and coronary heart disease (CHD) deaths (n=148) monitored through 1990. Median Lp(a) levels did not differ between cases and controls and mean apo(a) size did not vary between cases and controls in the entire study population. When adjusted for age and Lp(a) concentration, logistic regression analysis indicated that small apo(a) isoforms were associated with CHD deaths among smokers (OR 3.31; 95% CI 1.07-10.28).
Adult↗
Retroviral infection of the FGF2 gene into MCF-7 cells induces branching morphogenesis, retards cell growth and suppresses tumorigenicity in nude mice.
FGF2 (basic fibroblast growth factor) is a multifunctional growth factor and exhibits diverse function in different cell types. In breast, loss of FGF2 expression is associated with malignant progression. In order to understand the role of FGF2 in maintenance of normal breast structures and control of cell growth, we restored FGF2 expression in the breast cancer cell line MCF-7. The FGF2 retrovirally infected MCF-7 cells (MCF-7.F2.5) not only expressed FGF2 in cytoplasm and nuclei, but also released FGF2 into culture medium both on plastic and in Matrigel conditions. The MCF-7.F2.5 cells formed branches in Matrigel and this effect was abolished by the addition of a neutralising anti-FGF2 antibody or function blocking antibodies to alpha2, alpha3 and beta1 integrins. Furthermore, MCF-7.F2.5 cells lost their ability for anchorage-independent growth in soft agar. When MCF-7 and MCF-7.F2.5 cells were injected into nude mice, there was a 1.6- to 3.2-fold reduction of tumour volume with MCF-7.F2.5 cells in comparison with the parental MCF-7 cells. MCF-7.F2.5 cells also demonstrated a reduction in oestrogen receptor-alpha (ERalpha) both in vitro and in vivo. Our results suggest that introduction of the FGF2 gene into MCF-7 cells altered the malignant tumour cells towards a more benign phenotype in vitro and in vivo.
Animals↗
The 3' non-coding region of a C4 photosynthesis gene increases transgene expression when combined with heterologous promoters.
The Me1 gene of the dicot Flaveria bidentis encodes NADP malic enzyme, which catalyses the decarboxylation reaction of C4 photosynthesis in bundle sheath cells. We have previously shown that the 3' non-coding region (Me1 3') controls quantitative expression of the gene. We wondered whether Me1 3' can increase expression when combined with heterologous promoters. We tested a highly expressed, constitutive promoter, the S4 promoter from subterranean clover stunt virus, and a highly expressed, leaf-specific promoter, the light-harvesting chlorophyll a/b-binding protein gene 3 (Lhcb3) promoter of Arabidopsis thaliana. Promoter-3'-end combinations were tested in transgenic C4 Flaveria plants and C3 tobacco. We found that Me1 3' increased expression of the gusA reporter gene several-fold in leaves of both species in combination with either of the promoters. In both cases Me1 3' does not alter the expression pattern for either promoter. We conclude that Me1 3' can be used as a transcription terminator to increase transgene expression in C3 dicot plants.
3' Untranslated Regions↗
Quantitative regulation of the Flaveria Me1 gene is controlled by the 3'-untranslated region and sequences near the amino terminus.
The Me1 gene of Flaveria bidentis codes for the C4 isoform of NADP malic enzyme, which accumulates to a high-level only in bundle sheath cells. Previous experiments demonstrated that sequences at the 5' end of the gene control cell specificity whereas sequences at the 3' end are necessary for high-level expression. To localize quantitative regulator sequences, we have analysed a series of Me1 3' deletion constructs fused to the gusA reporter gene. We show that sequences within the 3'-untranslated region (3'-UTR) control quantitative levels of expression. Analysis of 5' promoter fusions demonstrated that high-level expression also requires sequences within the N-terminal coding region of the gene, suggesting possible interactions between the 3'-UTR and 5' coding regions. Cell-specific regulatory sequences are located in a different part of the 5' end of the gene, between 1023 bp upstream of the transcription start and the start of translation.
3' Untranslated Regions↗