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C J Barnes

Publications and source records attributed to C J Barnes.

At least 19 recordsLinked to original sources
PubMed2004

Novel estrogen receptor coregulators and signaling molecules in human diseases.

The steroid hormone estrogen and signaling from its receptors are increasingly recognized as critical mediators of a variety of organ-specific biological processes. Recent advances in the identification and functional characterization of novel estrogen receptor interacting proteins clearly show the complexity of hormonal signaling regulation, but may also contribute to our understanding of the roles of estrogen signaling in normal physiology and the pathobiology of human disease.

Bone and Bones↗
PubMed2001

Growth factor regulation of the molecular chaperone calnexin.

Heregulin-beta1 (HRG) is a regulatory polypeptide having several distinct biological effects in mammary epithelial cells. To address the hypothesis that HRG selectively regulates gene expression, we performed differential display screening using cells grown in the presence or absence of HRG. One cDNA clone upregulated by HRG was identical to human calnexin, a protein with molecular chaperone function. This is the first demonstration of the regulation of calnexin mRNA and protein expression by a physiologically relevant polypeptide factor in human breast cancer cells. HRG stimulation also caused a rapid redistribution of calnexin from vesicle-like structures in the cell cytoplasm to the perinuclear area and to the cell membrane. Furthermore, HRG induced colocalization and physical interaction of calnexin with the HER2 growth factor receptor. Finally, calnexin protein levels were increased in progressive stages of human breast cancer. These findings suggest that stimulation of calnexin expression by HRG may constitute a mechanism of protein redistribution and facilitate downstream signaling events in growth-factor-activated cells.

Breast Neoplasms↗
PubMed2000

Inactivation of germline mutant APC alleles by attenuated somatic mutations: a molecular genetic mechanism for attenuated familial adenomatous polyposis.

Germline mutations of the adenomatous polyposis coli (APC) tumor-suppressor gene result in familial adenomatous polyposis (FAP). Patients with FAP typically develop hundreds to thousands of benign colorectal tumors and early-onset colorectal cancer. A subset of germline APC mutations results in an attenuated FAP (AFAP) phenotype, in which patients develop fewer tumors and develop them at an older age. Although a genotype-phenotype correlation between the locations of APC germline mutations and the development of AFAP has been well documented, the mechanism for AFAP has not been well defined. We investigated the mechanism for AFAP in patients carrying a mutant APC allele (APC(AS9)) that has a mutation in the alternatively spliced region of exon 9. APC(AS9) was found to down-regulate beta-catenin-regulated transcription, the major tumor-suppressor function of APC, as did the wild-type APC. Mutation analysis showed that both APC(AS9) and the wild-type APC alleles were somatically mutated in most colorectal tumors from these patients. Functional analysis showed that 4666insA, a common somatic mutation in APC(AS9) in these tumors, did not inactivate the wild-type APC. Our results indicate that carriers of APC(AS9) develop fewer colorectal tumors than do typical patients with FAP because somatic inactivation of both APC alleles is necessary for colorectal tumorigenesis. However, these patients develop colorectal tumors more frequently than does the general population because APC(AS9) is inactivated by mutations that do not inactivate the wild-type APC.

Adenomatous Polyposis Coli↗
PubMed1999

Presence of well-differentiated distal, but not poorly differentiated proximal, rat colon carcinomas is correlated with increased cell proliferation in and lengthening of colon crypts.

To determine whether colon crypt proliferative parameters were significantly altered by the stage of colon carcinogenesis or the type or location of colon tumors in rats, male Sprague-Dawley rats received an injection of the carcinogen 1,2-dimethylhydrazine (12 mg DMH base/kg body weight) or DMH vehicle once a week for 8 weeks, then were killed 24 weeks later. Three hours before sacrifice, rats were injected with 1 mg/kg body weight colchicine to arrest mitotic cells at metaphase. Transverse sections of the colon mucosa were taken 6 cm from the anus and at least 3 cm from any tumor, fixed in formalin, then stained with hematoxylin & eosin (H&E) for analyses of proliferative parameters. Only complete, mid-axial crypts were scored for mitotic count (MC), crypt proliferative zone (PZ) height and crypt height (CH). Serial tumor sections were stained with H&E for histological evaluation or used in immunohistochemical detection of transforming growth factor alpha (TGF alpha). DMH treatment significantly increased MC, PZ and CH regardless of tumor status. The PZ and CH of rats with a carcinoma located in the distal colon were significantly increased compared with DMH-treated rats without an adenocarcinoma (AC) or with rats which had a tumor located in the proximal colon. Distal colon ACs were found to be well differentiated and to have greater TGF alpha immunoreactivity than the generally less differentiated proximal colon carcinomas. Distal colon AC production and systemic circulation of a soluble colon crypt stimulating factor such as TGF alpha may explain the significant increase in PZ and CH in histologically normal colonic mucosa located away from the tumor.

1,2-Dimethylhydrazine↗
PubMed1999

Determination of an optimal dosing regimen for aspirin chemoprevention of 1,2-dimethylhydrazine-induced colon tumours in rats.

In order to establish an optimal timing and duration of aspirin treatment in the chemoprevention of 1,2-dimethylhydrazine (DMH)-induced colon cancer in rats, colon tumours were induced using an established protocol and aspirin was given in the diet at 500 p.p.m. during various stages of colon carcinogenesis. Results indicate that only aspirin treatment throughout the entire carcinogenic period significantly reduced tumour incidence and volume whereas intermittent aspirin dosing increased tumour number and/or volume, suggesting that aspirin must be used for an extended period in order to gain any chemopreventive benefit.

1,2-Dimethylhydrazine↗
PubMed1999

Effect of aging and dietary restriction on rat testicular germ cell apoptosis.

The purpose of this study was to determine whether apoptotic cell death of rat testicular germ cells varies with increased age or with dietary restriction. Slide-mounted cross-sections of formalin-fixed testis from 4-, 13-, and 23-month-old ad-libitum-fed and 40% dietary-restricted male F344 rats were used in an in situ assay for apoptotic germ cells. Results show that in ad-libitum-fed rats, increased age caused a significant increase in the percentage of seminiferous tubules containing apoptotic cells, but a significant decrease in the number of apoptotic cells per apoptosis-positive tubule. In the 23-month-old rats, dietary restriction significantly increased both the percentage of apoptotic positive tubules and the number of apoptotic cells per apoptosis-positive tubule above ad-libitum-fed values. Both ad-libitum and diet-restricted groups demonstrated a decrease in the percentage of apoptotic spermatogonia concomitant with a significant increase in the percentage of apoptotic primary spermatocytes with advanced age. The significant age-related increase in total numbers of apoptotic germ cells may reflect elimination of defective germ cells, which occurs with increased frequency in advanced age. Dietary restriction may induce enhanced screening against defective germ cells above that seen in the ad-libitum-fed rats. These results have potential implications in aging studies as well as research involving perturbation of normal germ cell homeostasis.

Aging↗
PubMed1999

Effect of aspirin on prostaglandin E2 formation and transforming growth factor alpha expression in human rectal mucosa from individuals with a history of adenomatous polyps of the colon.

Colorectal cancer is the second-most frequent cause of cancer mortality in the United States. Human epidemiology and laboratory studies indicate that aspirin may be an effective colorectal cancer chemopreventive agent. This study was designed to determine whether treatment with 81 mg of aspirin per day for 3 months would alter two putative surrogate end point biomarkers of chemoprevention of colorectal cancer [i.e., mucosal prostaglandin E2 (PGE2) formation and transforming growth factor alpha (TGF-alpha) expression] in normal-appearing rectal mucosa from individuals with a history of adenomatous polyps. Rectal biopsies were obtained by flexible sigmoidoscopy at three sequential time points: (a) after a 1-month placebo run-in period (baseline), (b) after 3 months of ingesting 81 mg of aspirin (as a single tablet) once per day, and (c) after 3 months of ingesting a placebo tablet once per day (washout period). Daily aspirin significantly suppressed PGE2 formation, but this significant suppression was completely reversed when aspirin was withdrawn. The extent of TGF-alpha staining in rectal crypts was also reduced significantly (P = 0.039) by daily aspirin. After a 3-month placebo-washout period, however, the mean extent of TGF-alpha staining was not significantly different from either baseline or the aspirin time point. Thus, 81 mg of aspirin daily significantly reduced rectal mucosal PGE2 formation and TGF-alpha expression in patients with a history of adenomatous polyps. These putative surrogate end point biomarkers may be useful intermediate end points in future colorectal cancer chemoprevention trials.

Adenomatous Polyps↗
PubMed1998

Age-dependent sensitization to oxidative stress by dietary fatty acids.

Experiments were designed to test the hypothesis that short-term feeding of a high polyunsaturated fatty acid (PUFA) diet would increase susceptibility to lipid peroxidation in an age-dependent manner. Young (6 month) and old (24 month) male B6C3F1 mice were fed modified AIN-76 diets containing either 5% corn oil (CO, N = 5 per age group) or 19% fish oil plus 1% corn oil (FO, N = 20 per age group) for two weeks. Five CO and five FO diet mice per age received an intraperitoneal injection of normal saline and were sacrificed one hour later; the remaining FO diet mice (N = 15 per age) were challenged with an acute systemic oxidative stress by intraperitoneal injection of 125 mg iron/kg body weight as iron dextran, and were sacrificed 1, 5, and 24 hours post-injection. Microsomal membrane fatty acid analysis revealed that increased age and a FO diet significantly increased membrane PUFA content. Serum iron levels increased significantly following iron treatment, peaking at 5 hours in both age groups. Formation of microsomal malondialdehyde (MDA), a product of lipid peroxidation, was significantly greater in the livers of the young mice. The temporal patterns of serum iron and microsomal MDA concentrations were significantly correlated in young mice, but not in old mice. Histochemical examination showed that liver iron accumulation following iron injection was similar in both age groups, but was associated with a significant temporal increase in liver apoptotic cells in young mice, but not in old mice. Thus, both age groups had similar iron exposure and iron accumulation, and the liver microsomal membranes of old mice were more unsaturated, yet there was significantly greater peroxidative damage (MDA formation) and cell death (apoptosis) in the young mouse livers. These findings suggest that the older animals have upregulated antioxidant defenses.

Aging↗
PubMed1998

Effect of aging on spontaneous and induced mouse testicular germ cell apoptosis.

The purpose of this study was to determine whether apoptotic cell death of mouse testicular germ cells varies with increased age, or with exposure to an acute systemic oxidative stress. Results show that the percent of seminiferous tubules with apoptotic cells, and the number of apoptotic cells/tubule cross section were not significantly altered with age. However, there were significantly more apoptotic metaphase spermatocytes at tubule stage XIV in 24-month-old mice than in 6-month-old mice. Oxidative stress significantly increased apoptotic metaphase spermatocytes in young mice, and severely reduced testicular apoptosis in old mice. Our results have potential clinical relevance to changes with increased age in human sperm aneuploidies.

Aging↗
PubMed1998

Chemoprevention of spontaneous intestinal adenomas in the adenomatous polyposis coli Min mouse model with aspirin.

BACKGROUND & AIMS: Colorectal cancer is a significant source of morbidity and mortality in the United States and other Western countries. Epidemiological and experimental data indicate that regular use of aspirin reduces colon cancer risk. This study was designed to determine if aspirin would significantly inhibit gastrointestinal tumor formation in a mouse model of familial adenomatous polyposis. METHODS: Six-week-old male and female C57BL/6J +/+ (control) and C57BL/6J ApcMin/+ (Min) mice were fed either a control AIN-76A diet or one supplemented with 250 or 500 parts per million (ppm) aspirin (n = 6 per group) for 7 weeks. RESULTS: All of the Min mice, but no control mice, developed gastrointestinal tumors. Aspirin significantly reduced tumor multiplicity (number of tumors per mouse) in the small intestine, but not the colon, from an average of 35.8 tumors per mouse (control diet) to 16 and 18.5 tumors per mouse with 250 and 500 ppm aspirin, respectively. Total tumor load (sum of tumor diameters per mouse) was also significantly reduced, from 93.2 mm in total diameter to 40. 4 and 45.0 mm with 250 and 500 ppm aspirin, respectively. Results were not significantly different because of sex or aspirin dose. CONCLUSIONS: High doses of aspirin are effective chemopreventive agents in a mouse model of spontaneous intestinal tumor formation.

Adenoma↗
PubMed1998

Non-steroidol anti-inflammatory drug effect on crypt cell proliferation and apoptosis during initiation of rat colon carcinogenesis.

Sustained use of non-steroidal anti-inflammatory drugs (NSAIDs) may prevent colorectal cancer. However, the optimal drug, period of efficacy and mechanism(s) of action are unknown. Experiments were undertaken to determine which of several NSAIDs would modulate colon crypt cell proliferation or apoptosis when given during the initiation phase of 1,2-dimethylhydrazine (DMH)-induced rat colon cancer. Colon crypts located both away from and over an aggregate of lymphoid nodules (ALN) were examined. Rats were injected with aspirin, indomethacin, nabumetone, sodium salicylate, 16,16-dimethyl prostaglandin E2 or saline for 3 days and DMH or DMH vehicle on day 4 of each week for 8 weeks, then killed 3 days after the last DMH injection. At the time of killing, DMH had significantly increased crypt cell proliferation but not apoptosis. There was significantly more cell proliferation and apoptosis in crypts over the ALN than away from the ALN. Aspirin and salicylate increased proliferation and apoptosis in crypts over the ALN. Finally, the distributional peaks of cell proliferation and apoptosis were shifted significantly closer together after DMH. Thus, DMH increases proliferation and alters the distribution of proliferating and apoptotic cells in colon crypts early in carcinogenesis. Aspirin may suppress tumour incidence via salicylate by enhancing apoptosis in carcinogen-initiated cells.

1,2-Dimethylhydrazine↗
PubMed1997

Aspirin, but not sodium salicylate, indomethacin, or nabumetone, reversibly suppresses 1,2-dimethylhydrazine-induced colonic aberrant crypt foci in rats.

The aim of this study was to determine if selective inhibition of cyclooxygenase isozymes affects the initiation of carcinogen-induced colon cancer using aberrant crypt foci (ACF) as a surrogate biomarker. Male Sprague-Dawley rats (18 per group) were given single subcutaneous injections of saline (4 ml/kg), aspirin (50 mg/kg body wt) sodium salicylate (50 mg/kg), indomethacin (4 mg/kg), nabumetone (100 mg/kg), or 16,16-dimethyl-prostaglandin E2 (50 mg/kg) for three days. On day 4, 12 rats per group were given a subcutaneous injection of 1,2-dimethylhydrazine (12 mg base/kg body wt) and six rats per group received vehicle alone (4 ml/kg) every week for eight weeks, after which drug treatment ceased. Control and six carcinogen-treated rats per group were killed at this time and the remaining six rats per group killed 22 weeks later. Colons were scored for ACF number and size. Only aspirin caused a significant reduction in total ACF and ACF formation at the early time point, but at the later time, there were no significant differences between groups. ACF from all treatment groups increased in size at similar rates at both time points. Thus, only aspirin demonstrated a significant, although reversible, suppression of carcinogen-induced ACF. Possible mechanisms of action and the clinical implications of aspirin chemoprevention are discussed.

1,2-Dimethylhydrazine↗
PubMed1997

Effects of iron supplementation and ET-18-OCH3 on MDA-MB 231 breast carcinomas in nude mice consuming a fish oil diet.

Lipid peroxidation products can be cytotoxic. Our objectives were (1) to use two pro-oxidants (iron and a pro-oxidative drug) to selectively increase lipid peroxidation in the implanted human breast tumours of mice consuming fish oil and (2) to kill the cancer cells without harming normal host tissues. The theoretical basis for selective cytotoxicity is that normal cells are better able to handle oxidative stress than cancer cells. Male athymic nude mice, consuming an AIN-76 diet, were injected s.c. with MDA-MB 231 human breast carcinoma cells. Three weeks later, all mice had palpable tumours, 3-10 mm in diameter, and diets were changed to modified AIN-76 diets containing 19% menhaden fish oil and 1% corn oil with or without supplemental 0.3% ferric citrate. After 2 weeks, half of the mice on each diet (19% fish oil with or without supplemental ferric citrate) were injected (three times per week for 2 weeks) with the ether-lipid drug edelfosine (ET-18-OCH3). The concentration of lipid peroxidation products in tumours (as measured by thiobarbituric acid-reactive substances, TBARS) was significantly increased by both ferric citrate and ET-18-OCH3. The TBARS in livers were not increased, nor was there evidence of other harmful side-effects to the host mice. The addition of iron enhanced tumour cell death whereas ET-18-OCH3 suppressed tumour cell mitosis. The use of iron supplementation combined with ET-18-OCH3 resulted in the slowest growth rate, lowest mitotic index, highest level of lipid peroxidation products and increased the cytotoxic index in tumours without detectable harm to the host. That iron supplementation increased tumour suppression beyond that expected from the increase in the concentration of TBARS in the tumour merits further investigation.

Animals↗
PubMed1997

Stalkers: the South Carolina experience.

Medical records of 18 pretrial detainees charged with stalking were evaluated at a forensic unit in Columbia, South Carolina from January 1992 to December 1994 and their records were compared with those of 18 offenders in the same unit randomly matched for sex, race, and whether associated crimes were violent or not. Compared variables included age, marital status, level of education, substance abuse, Axis I diagnosis, prior psychiatric hospitalizations, military history, and organicity. Significant findings show that alleged stalkers were better educated, less likely to be married or to abuse substances, and more likely to have military training and organicity when compared with other offenders. The prototypical stalker in this study is a single, educated male who is likely to have military training as well as some degree of organicity. He is less likely than other offenders to abuse substances. Replication studies are needed.

Adolescent↗
PubMed1996

Mechanism of tracking and cleavage of adduct-damaged DNA substrates by the mammalian 5'- to 3'-exonuclease/endonuclease RAD2 homologue 1 or flap endonuclease 1.

The mammalian 5'- to 3'-exonuclease/endonuclease, called RAD2 homologue 1 or flap endonuclease 1, has a unique cleavage activity, dependent on specific substrate structure. On a primer-template, in which the primer has an unannealed 5'-tail, endonucleolytic cleavage near the annealing point releases the tail intact. Entering at the 5'-end, the nuclease tracks along the entire tail to the point of cleavage. Genetic analyses suggest that this nuclease removes DNA adducts in vivo (Sommers, C. H., Miller, E. J., Dujon, B., Prakash, S., and Prakash, L. (1995) J. Biol. Chem. 270, 4193-4196). Micrococcal nuclease footprinting shows that after tracking the nuclease protects a region of the tail 25 nucleotides long, adjacent to the cleavage site. Substrates with adducts at specific locations were used to assess the mechanism of RAD2 homologue 1 nuclease tracking and its ability to cleave modified DNA. Either a conventional cis-diamminedichloroplatinum (II) (CDDP) or a bulky CDDP derivative was placed within or beyond the region protected by the nuclease. The nuclease cleaved the tail of both substrates. In contrast, a CDDP adduct just adjacent to the expected cleavage point was inhibitory. A CDDP adduct at the very 5'-end of the tail was also cleaved. The nuclease could remove tails containing adducts on the sugar-phosphate backbone. Apparently, the nuclease is designed to slide over various types of damage on single stranded DNA and then cut past the damaged site.

Animals↗
PubMed1996

Calf RTH-1 nuclease can remove the initiator RNAs of Okazaki fragments by endonuclease activity.

In eukaryotes, the endonucleolytic activity of the calf RTH-1 class 5'- to 3'-exo/endonuclease can function without RNase H1 to remove initiator RNA from Okazaki fragments. Cleavage requires that the RNA be displaced to form an unannealed single-stranded 5'-tail or flap structure. On substrates with RNA-initiated primers, DNA oligomers that competed with the RNA for template binding simulated strand displacement synthesis from an upstream Okazaki fragment. This allowed cutting of displaced RNA segments by RTH-1 nuclease. Requirements for the reaction also were examined on substrates in which the tail was unannealed because it was intentionally mispaired. On both types of substrate, the nuclease slides over the RNA region from the 5'-end and cleaves at the beginning of the annealed region, irrespective of whether ribo- or deoxyribonucleotides are at the cleavage site. Presence of a triphosphate or a 7-methyl 3'G5'ppp5' G cap structure at the 5'-end of the RNA does not affect cleavage. The previously reported stimulation of the nuclease by an upstream primer was not always observed, suggesting that not every site in the downstream Okazaki fragment is equally susceptible to cleavage during displacement synthesis in vivo. The biological role of the endonuclease activity of RTH-1 nuclease in Okazaki fragment processing is discussed.

Animals↗
PubMed1996

Aspirin suppresses 1,2-dimethylhydrazine-induced alteration of proliferative parameters in rat colonic crypts.

Human epidemiological reports and rodent experimental research data indicate a possible chemopreventive effect of regular aspirin use for decreasing risk of colon and rectum cancer incidence and mortality. We have previously demonstrated that aspirin can significantly suppress proliferative parameters in normal rat colonic epithelium when examined 24 h following an acute or chronic course of aspirin administration. To investigate whether aspirin would effectively suppress known carcinogen-induced changes in colonic epithelium, rats were given single s.c. injections of either aspirin (50 mg/kg bw) or saline on days 1-3 and either 1,2-dimethylhydrazine (DMH; 12 mg base/kg bw) or DMH vehicle on day 4 of each week for eight consecutive weeks. Rats were sacrificed 4 days after the last aspirin dose and 3 days after the last DMH or DMH vehicle dose. Using the proliferative biomarkers of proliferating cell nuclear antigen positive cells per midaxial crypt section (SCC), crypt proliferative zone height (PZ), crypt differentiated zone height (DZ), and total crypt height (CH), it was found that aspirin does suppress DMH-induced increases in SCC, PZ and CH. The findings demonstrate that aspirin has a long term (i.e. several days) protective effect against early carcinogen-induced proliferative changes in rat colonic crypts which may help account for aspirin's chemopreventive action against colon cancer.

1,2-Dimethylhydrazine↗