Anuradha Mudipalli - Academia.edu (original) (raw)

Papers by Anuradha Mudipalli

Environmental and Molecular Mutagenesis, 1997

Reductive activation of mitomycin C leads to its covalent binding to DNA, forming monoadducts and... more Reductive activation of mitomycin C leads to its covalent binding to DNA, forming monoadducts and cross-links. The cytotoxicity of mitomycin C has been attributed to cross-link formation, whereas monoadducts are assumed to cause mutagenicity. We have developed a 32P-postlabeling technique to measure mitomycin C DNA adducts. Using this technique, we have measured monoadduct formation in the shuttle vector plasmid pSP189 and have determined mutations induced by monoadduct formation. The shuttle vector plasmid was incubated with mitomycin C under conditions favoring monofunctional activation of mitomycin C. The plasmid was then replicated in human Ad293 cells, rescued in bacteria, and analyzed for mutations in the supF tRNA gene sequence of pSP189. One major mitomycin C/DNA adduct was observed by 32P-postlabeling and was characterized as a monoadduct of guanine. When pSP189 was exposed to monofunctionally activated mitomycin C, increases in adduct levels and mutation frequency were found to be related to mitomycin C concentration. The majority of the mutations involved single bases, with base substitutions making up 59.1% of the total mutations observed. Of the base substitutions, 67.2% were transversions and 32.8% were transitions, with nearly 80% of all base substitutions involving G:C base pairs. Deletions, either as single bases or large deletions, also involved G:C base pairs the majority of the time. The observed bias of mutations at G:C and the formation of a mitomycin C/DNA monoadduct involving guanine suggests that monoadduct formation may be responsible for the mutations.

PubMed, Dec 1, 2007

Occupational and environmental exposures to lead (Pb), one of the toxic metal pollutants, is of g... more Occupational and environmental exposures to lead (Pb), one of the toxic metal pollutants, is of global concern. Health risks are increasingly associated with environmental exposures to Pb emissions from, for example, the widespread use of leaded gasoline in developing countries. Exposure occurs mainly through the respiratory and gastrointestinal systems, and the ingested and absorbed Pb is stored primarily in soft tissues and bone. Autopsy studies of Pb-exposed patients have shown a large amount (approximately 33%) of the absorbed Pb in soft tissue stored in liver. In addition to neuronal encephalopathy observed in persons after exposure to very high concentrations of Pb, gastrointestinal colic (abdominal pain, constipation, intestinal paralysis) is a consistent early symptom of Pb poisoning in humans. Such severe gastrointestinal effects are consistently observed in patients with a blood Pb range of 30 to 80 microg/dl. Ingestion of Pb is one of the primary causes of its hepatotoxic effects. Hepatocarcinogenic effects of Pb reported in animal toxicology studies have led to new research into the biochemical and molecular aspects of Pb toxicology. Gains in the molecular understanding of Pb effects on hepatic drug metabolizing enzymes, cholesterol metabolism, oxidative stress, and hepatic hyperplasia suggest a potential role for Pb in damaging extrahepatic systems, including the cardiovascular system. This review also discusses the therapeutic potential of chelation therapy in treating Pb-induced hepatotoxicity in animals.

In Vitro Cellular & Developmental Biology – Animal, Oct 1, 2000

Stromal-epithelial interactions play a profound role in regulating normal and tumor development i... more Stromal-epithelial interactions play a profound role in regulating normal and tumor development in the mammary gland. The molecular details of these events, however, are incompletely understood. A novel serum-free transwell coculture system was developed to study the natural paracrine interactions between mammary epithelial cells (MEC) and mammary fibroblasts (MFC) isolated from normal rats during puberty. The MEC were cultured within a reconstituted basement membrane (RBM) in transwell inserts with or without MFC in the lower well. The presence of MFC stimulated epithelial cell growth, induced alveolar morphogenesis, and enhanced casein accumulation, a marker of the functional differentiation of MEC, but did not induce ductal morphogenesis. Potent mitogenic, morphogenic, and lactogenic effects were observed when the MFC were cultured either on plastic or within a layer of RBM. Although most MFC maintained on plastic died after 1 wk in serum-free medium, fibroblast survival was enhanced significantly when the MFC were cultured within the RBM. Taken together, this in vitro model effectively reconstitutes a physiologically relevant three-dimensional microenvironment for MEC and MFC, and seems ideal for studying the locally derived factors that regulate the developmental fate of the epithelial and fibroblast compartments of the mammary gland.

Leukemia, 2001

ML-1 human myeloblastic leukemia cells, suspended in serumdepleted medium, proliferate when the i... more ML-1 human myeloblastic leukemia cells, suspended in serumdepleted medium, proliferate when the insulin-like growth factor-1 (IGF-1) and transferrin (Tf) are supplied, but differentiate to monocytes when these factors are replaced by the tumor necrosis factor-α (TNF-α). Induction of differentiation, but not of proliferation, involved the selective activation of diverse members of the NF-κB family of proteins. In differentiationinduced cells, NF-κB (p65) was translocated from the cytoplasm to the nucleus, whereas NF-κB (p75) remained localized to the cytoplasm. In contrast, NF-κB (p52) was present in the nuclei of proliferation-as well as of differentiation-induced ML-1 cells. The differentiation-specific translocation of NF-κB (p65) from the cytoplasm to the nucleus was mediated by an increase in the level of NIK, the NF-κB-inducing kinase which, through phosphorylation of IκB kinase α (Iκkα), causes a decrease in the level of IκBα, allowing p65 to move from the cytoplasm to the nucleus. The p52/p65 heterodimer formed in the nucleus, bound specifically to the promoter of the tumor suppressor protein p53, effecting a 25 to 30-fold increase in the level of this protein. As we reported previously (Li et al, Cancer Res 1998; 58: 4282-4287), that increase led to the decreased expression of proliferating cell nuclear antigen (PCNA) and to the loss of proliferation-associated DNA synthesis. The ensuing uncoupling of growth from differentiation was followed by the initiation of the monocyte-specific differentiation program.

Cancer Prevention Research

Cadmium is a nonessential heavy metal, ubiquitous in nature with a long half-life in human beings... more Cadmium is a nonessential heavy metal, ubiquitous in nature with a long half-life in human beings. It is widely used in various industrial applications such as toy and jewelry making and is one of the key constituents of tobacco and cigarette smoke. Cadmium, both at occupational and environmental levels, has been implicated in the causation of cancerous and noncancerous health outcomes. In comparison, iron is an essential metal and is a constituent of hemoglobin and many vital enzymes and proteins and plays a pivotal role in human health. However, increased consumption of iron from fortified diets and iron supplements presents opportunities for exposure to supraphysiologic iron concentrations and toxicity. Additionally, hereditary iron disorders (thalassemia, hereditary hemochromatosis), other disease conditions such as cancer and kidney diseases, and certain environmental exposures (e.g., steel-welding fumes, asbestos, and air pollution) could also lead to iron toxicity with distur...

The heavy metal cadmium is ubiquitous in the environment. Occupational exposures to cadmium have ... more The heavy metal cadmium is ubiquitous in the environment. Occupational exposures to cadmium have long been linked to cancers of various organs. Emerging epidemiological data, although often limited by study deficits, provide convincing evidence of lung, kidney, prostate, and breast cancers after cadmium exposure. Experimental evidences from animal models and in vitro cell culture systems aid in discerning the molecular pathways of these cancers and provide biological plausibility for cadmium carcinogenesis. The International Agency for Research on Cancer declared cadmium as group I carcinogen with sufficient evidence for cancer in humans. This chapter discusses the molecular pathways of cadmium carcinogenesis for specific organs followed by a brief discussion on general molecular pathways of cadmium-induced carcinogenesis. Finally, conclusions are drawn on the existing database in order to identify common and unique molecular pathways of these cancers and to infer biological plausib...

International journal of oncology, 2005

The molecular mechanisms mediating arsenic-induced carcinogenesis are not well understood. The ro... more The molecular mechanisms mediating arsenic-induced carcinogenesis are not well understood. The role of confounding factors such as ultraviolet radiation (UV), add another level of complexity to the study of arsenic carcinogenesis and the cancer-risk assessment on humans. We hypothesized that arsenicals are capable of overriding the growth arrest caused by UV treatment and may lead to selective proliferation. To test this hypothesis, a primary normal human epidermal keratinocyte (NHEK) cell culture model was used. One group was pre-exposed to UVB (100 mJ/cm(2)) that arrested a majority ( approximately 95%) of cells in G0/G1 (+UV) and a second group was not exposed to UV (-UV). Treatment of cells with various arsenicals [0-12 microM of inorganic arsenite (iAs), 0-2 microM of methyl oxoarsine (MMAs III) and 0-3 microM of iododimethyl arsine (DMAs III)] indicated a concentration-dependent increase in proliferation at 24 h in the order of DMAs III > MMAs III > iAs. Flow-cytometric ...

Environment International, 2020

Background: Diethyl phthalate (DEP) is widely used in many commercially available products includ... more Background: Diethyl phthalate (DEP) is widely used in many commercially available products including plastics and personal care products. DEP has generally not been found to share the antiandrogenic mode of action that is common among other types of phthalates, but there is emerging evidence that DEP may be associated with other types of health effects. Objective: To inform chemical risk assessment, we performed a systematic review to identify and characterize outcomes within six broad hazard categories (male reproductive, female reproductive, developmental, liver, kidney, and cancer) following exposure of nonhuman mammalian animals to DEP or its primary metabolite, monoethyl phthalate (MEP). Methods: A literature search was conducted in online scientific databases (PubMed, Web of Science, Toxline, Toxcenter) and Toxic Substances Control Act Submissions, augmented by review of online regulatory sources as well as forward and backward searches. Studies were selected for inclusion using PECO (Population, Exposure, Comparator, Outcome) criteria. Studies were evaluated using criteria defined a priori for reporting quality, risk of bias, and sensitivity using a domain-based approach. Evidence was synthesized by outcome and life stage of exposure, and strength of evidence was summarized into categories of robust, moderate, slight, indeterminate, or compelling evidence of no effect, using a structured framework. Results: Thirty-four experimental studies in animals were included in this analysis. Although no effects on androgen-dependent male reproductive development were observed following gestational exposure to DEP, there was evidence including effects on sperm following peripubertal and adult exposures, and the overall evidence for male reproductive effects was considered moderate. There was moderate evidence that DEP exposure can lead to developmental effects, with the major effect being reduced postnatal growth following gestational or early postnatal exposure; this generally occurred at doses associated with maternal effects, consistent with the observation that DEP is not a potent developmental toxicant. The evidence for liver effects was considered moderate based on consistent changes in relative liver weight at higher dose levels; histopathological and biochemical changes indicative of hepatic effects were also observed, but primarily in studies that had significant concerns for risk of bias and sensitivity. The evidence for female reproductive effects was considered slight based on few reports of statistically significant effects on maternal body weight gain, organ weight changes, and pregnancy outcomes. Evidence for cancer and effects on kidney were judged to be indeterminate based on limited evidence (i.e., a single two-year cancer bioassay) and inconsistent findings, respectively. Conclusions: These results suggest that DEP exposure may induce androgen-independent male reproductive toxicity (i.e., sperm effects) as well as developmental toxicity and hepatic effects, with some evidence of female reproductive toxicity. More research is warranted to fully evaluate these outcomes and strengthen confidence in this database.

Environment International, 2018

Background: Biomonitoring studies indicate a trend towards increased human exposure to diisobutyl... more Background: Biomonitoring studies indicate a trend towards increased human exposure to diisobutyl phthalate (DIBP), a replacement for dibutyl phthalate (DBP). Recent reviews have found DIBP to be a male reproductive toxicant, but have not evaluated other hazards of DIBP exposure. Objective: To inform chemical risk assessment, we performed a systematic review to identify and characterize outcomes within six broad hazard categories (male reproductive, female reproductive, developmental, liver, kidney, and cancer) following exposure of nonhuman mammalian animals to DIBP or the primary metabolite, monoisobutyl phthalate (MIBP). Methods: A literature search was conducted in four online scientific databases [PubMed, Web of Science, Toxline, and Toxic Substances Control Act Test Submissions 2.0 (TSCATS2)], and augmented by review of regulatory sources as well as forward and backward searches. Studies were identified for inclusion based on defined PECO (Population, Exposure, Comparator, Outcome) criteria. Studies were evaluated using criteria defined a priori for reporting quality, risk of bias, and sensitivity using a domain-based approach. Evidence was synthesized by outcome and life stage of exposure, and strength of evidence was summarized into categories of robust, moderate, slight, indeterminate, or compelling evidence of no effect, using a structured framework. Results: Nineteen toxicological studies in rats or mice met the inclusion criteria. There was robust evidence that DIBP causes male reproductive toxicity. Male rats and mice exposed to DIBP during gestation had decreased testosterone and adverse effects on sperm or testicular histology, with additional phthalate syndrome effects observed in male rats. There was also evidence of androgen-dependent and-independent male reproductive effects in rats and mice following peripubertal or young adult exposure to DIBP or MIBP, but confidence was reduced because of concerns over risk of bias and sensitivity in the available studies. There was also robust evidence that DIBP causes developmental toxicity; specifically, increased post-implantation loss and decreased pre-and postnatal growth. For other hazards, evidence was limited by the small number of studies, experimental designs that were suboptimal for evaluating outcomes, and study evaluation concerns such as incomplete reporting of methods and results. There was slight evidence for female reproductive toxicity and effects on liver, and indeterminate evidence for effects on kidney and cancer. Conclusion: Results support DIBP as a children's health concern and indicate that male reproductive and developmental toxicities are hazards of DIBP exposure, with some evidence for female reproductive and liver toxicity. Data gaps include the need for more studies on male reproductive effects following postnatal and adult exposure, and studies to characterize potential hormonal mechanisms in females.

Molecular and Integrative Toxicology, 2017

The enrichment of milk with calcium is critical for the survival of mammals after birth. The proc... more The enrichment of milk with calcium is critical for the survival of mammals after birth. The process of transfer of calcium ions from the maternal blood supply into milk occurs through mammary alveolar epithelial cells. Recent research has provided deep mechanistic insight into these processes with candidates for the critical pathways involved in calcium transport identified. These proteins include the store-operated Ca2+ entry component Orai1 (basolateral Ca2+ influx), the secretory pathway Ca2+-ATPase isoform 2 (SPCA2, secretion of Ca2+), and the plasma membrane Ca2+-ATPase isoform 2 (PMCA2, apical membrane Ca2+ efflux). Increased expression of Orai1, SPCA2, and PMCA2 has also been identified in breast cancer cells; however, the remodeling of these targets often demonstrates selectivity for specific clinical and/or molecular subtypes. Silencing of these targets has identified roles for these proteins in the proliferation and/or migration of some breast cancer cell lines.

Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis, 1997

The relative mutagenicity, nature of the mutations and the sequence specificity of mutations indu... more The relative mutagenicity, nature of the mutations and the sequence specificity of mutations induced by the bifunctional alkylating agent, phosphoramide mustard (PM) and a monofunctional derivative, dechloroethyl phosphoramide mustard (dePM), were analyzed by the Ames test and by an in vitro shuttle vector mutagenesis assay. Both PM and dePM increased the mutation frequency above background in either assay. However, on an equimolar basis, dePM was less mutagenic than PM. In the in vitro shuttle vector mutagenesis assay, sequencing demonstrated that about 40% of the mutant plasmids contained more than one mutation in the supF tRNA gene segment of the plasmid. About 70% of the mutations observed in dePM-treated plasmids were single base substitutions with A:T and G:C base pairs being mutated at equivalent rates. In contrast, only about 50% of the mutations observed in PM-treated plasmids were single base substitutions, 80% of which involved G:C base pairs. Single base deletions and insertions were found in approximately equal proportions with both compounds; however, these lesions were in greater abundance in PM-treated plasmids. Putative hot-spots for mutation in the supF tRNA gene included base pairs at position 102 and 110 for PM and positions 170 and 171 for dePM.

Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis, 1995

The mutagenicity of the antitumor drug dacarbazine (DTIC) is due to alkylation of cellular DNA by... more The mutagenicity of the antitumor drug dacarbazine (DTIC) is due to alkylation of cellular DNA by metabolites resulting from the metabolism of this drug by the mixed function oxidase system. In the present study, we used an in vitro shuttle vector assay to study the base and sequence specificity of mutagenesis by DTIC. The shuttle vector plasmid pSPI89 was treated with DTIC (l-2.5 mM) in vitro in a reconstituted cytochrome P-450 system at 37°C for either 30 or 60 min. SupF tRNA gene insert contained in the plasmid was sequenced after replication of the drug-treated plasmid in human Ad 293 cells followed by amplification in indicator bacteria. Mutagenesis of DTIC in this system was dependent upon the presence of the cytochrome P-450 reconstituted system and NADPH. Mutations induced by DTIC included single base substitutions (35%), single base deletions (30..5%), single base insertions (19.4%) and large deletions (13.8%). Among the substitutions, transversions and transitions were in the ratio of 1:0.7. Base pairs 108 and 127 in the SupF tRNA of the pSP189 were identified as mutational hot spots.

The Indian journal of medical research, 2008

Iron is an essential trace metal required by all living organisms and is toxic in excess. Nature ... more Iron is an essential trace metal required by all living organisms and is toxic in excess. Nature has evolved a delicately balanced network to monitor iron entry, transport it to sites of need, and serve as a unique storage and recycling system, in the absence of an excretory system, to remove excess iron. Due to the unique nature of iron metabolism, iron homeostasis is achieved by integrated specialized mechanisms that operate at the cellular and organism level. The use of positional cloning approaches by multiple researchers has led to the identification and characterization of various proteins and peptides that play a critical role in iron metabolism. These efforts have led to elucidation of the molecular mechanisms involved in the uptake of iron by the enterocytes, transportation across the membrane to circulation, and delivery to diverse tissues for use and storage and sensor system to co-ordinate and achieve homeostasis. Molecular understanding of these processes and the key re...

The Indian journal of medical research, 2008

Why should wait for some days to get or receive the metals micro nutrients or toxicants global he... more Why should wait for some days to get or receive the metals micro nutrients or toxicants global health clinical report book that you order? Why should you take it if you can get the faster one? You can find the same book that you order right here. This is it the book that you can receive directly after purchasing. This metals micro nutrients or toxicants global health clinical report is well known book in the world, of course many people will try to own it. Why don't you become the first? Still confused with the way?

The Indian journal of medical research, 2007

Molecular Carcinogenesis, 1994

The cytotoxicity of the potent antibiotic and antitumor agent mitomycin C (MMC) is due to its irr... more The cytotoxicity of the potent antibiotic and antitumor agent mitomycin C (MMC) is due to its irreversible binding to DNA. Alkylating species generated by bioreductive activation of MMC are known to cause monoadducts and cross-links in DNA by specifically binding to guanine residues. To gain insight into how these lesions lead to base- and sequence-specific mutations, shuttle vector pSP189 was treated with MMC chemically reduced by treatment with sodium borohydride, replicated in human Ad293 cells, rescued in bacteria, and analyzed for mutations in the supF tRNA gene sequence. The MMC-induced mutations were predominantly base substitutions. Eighty-four percent of the base substitutions were transversions, with G:C--&amp;amp;amp;gt;T:A the major transversion. Single base deletions were the other major mutational event, and 77% of these were G:C deletions. Base positions 115, 123, and 163 were mutational hot spots based on the frequency of independent mutations. Identification of a single MMC adduct (presumed to be a modified G on the basis of its Rf value) and clustering of MMC-induced mutations at three GC-rich areas (nt 100-123, 152-163, and 168-176) suggested that the mutational spectrum we found was due to binding of MMC to guanine on either strand of the plasmid DNA.

Environmental and Molecular Mutagenesis, 1997

PubMed, Dec 1, 2007

In Vitro Cellular & Developmental Biology – Animal, Oct 1, 2000

Leukemia, 2001

Cancer Prevention Research

International journal of oncology, 2005

Environment International, 2020

Environment International, 2018

Molecular and Integrative Toxicology, 2017

Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis, 1997

Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis, 1995

The Indian journal of medical research, 2008

The Indian journal of medical research, 2007

Molecular Carcinogenesis, 1994