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C T Garrett

Publications and source records attributed to C T Garrett.

At least 55 records · Page 3Linked to original sources
PubMed1990

Serous papillary adenocarcinoma of the endometrium. Analysis of proto-oncogene amplification, flow cytometry, estrogen and progesterone receptors, and immunohistochemistry.

Primary and metastatic tumor tissues of serous papillary adenocarcinoma of the endometrium were examined for the following: (1) amplification of int-2, c-erbB-2 and c-myc proto-oncogenes by Southern blot hybridization; (2) DNA ploidy by flow cytometric study; (3) and expression of specific proteins, such as estrogen and progesterone receptors, keratin, vimentin, and carcinoembryonic antigen (CEA) using immunohistochemical and biochemical techniques. Amplification of c-myc was observed in the specimens from the endometrium (ten-fold) and from omental metastasis (five-fold). Both int-2 and c-erbB-2 amplification were not observed. The tumor showed aneuploidy, with the specimens from the endometrium and omental metastasis exhibiting multiple populations of aneuploid tumor cells. Estrogen and progesterone receptors could not be detected biochemically; however, immunohistochemically, estrogen receptors were observed in tumor cells forming papillary structures but not in the tumor cells of the solid, more poorly differentiated areas. A similar distribution was observed for both low and high molecular weight keratin. The findings of c-myc amplification and aneuploidy in the serous papillary adenocarcinoma of the endometrium are consistent with its aggressive behavior observed clinically and emphasize the importance of distinguishing this lesion from other types of endometrial carcinoma.

Blotting, Southern↗
PubMed1990

Nested polymerase chain reaction assay for the detection of cytomegalovirus overcomes false positives caused by contamination with fragmented DNA.

The polymerase chain reaction (PCR) technique offers a promising alternative to tissue culture for the rapid and sensitive detection of cytomegalovirus (CMV) infection. However, high levels of background amplification detected in samples containing water but no DNA make interpretation of borderline positive samples extremely difficult and reduce the sensitivity of the assay. The signal from amplification of water or positive samples can be eliminated by DNase treatment, but not by filtration through anisotropic membrane, autoclaving, or ultraviolet irradiation. A lag time of 10 to 12 cycles is observed before the reactions with water will show product formation by liquid hybridization detection. The use of nested PCR eliminates the background and, in serial dilutions of a positive sample, shows a 500- to 1000-fold increase in sensitivity by liquid hybridization detection. We suggest that the background signal is arising from small fragments of DNA, which may be produced by autoclaving viral culture material. Such fragments would escape filtration, and overlapping fragments of DNA can prime one another to form complete mosaic sequences that will then amplify. Nested PCR, appropriately controlled for the number of cycles at each step, should successfully overcome such false positives caused by fragmented DNA, no matter if the contamination occurs at the collection site, in processing, or at the facility performing the test.

Base Sequence↗
PubMed1990

Protooncogene amplification and tumor ploidy in human ovarian neoplasms.

DNA from 24 ovarian tumors, including 16 carcinomas, was examined for amplification of the proto-oncogenes c-myc, int-2, and rc-erbB-2. All cases of carcinoma were also examined by flow cytometry for DNA ploidy and cell cycle analysis, and eight cases of carcinoma were examined for estrogen and progesterone receptors. Protooncogene amplification was not detected in the DNA of benign ovarian neoplasms, or of ovarian carcinomas with low malignant potential. Amplification of c-myc was detected in six of 12 cases of invasive carcinoma, int-2 amplification was present in one case, and c-erbB-2 amplification was not detected in any case. Among the seven cases evidencing protooncogene amplification, three cases showed aneuploidy in tumor DNA, while four showed diploidy. Two cases which showed aneuploidy in tumor DNA did not demonstrate any degree of protooncogene amplification. Protooncogene amplification was frequently associated with morphologic nuclear anaplasia and high mitotic count. Six of the seven cases demonstrating c-myc or int-2 were of the serous type or showed some degree of serous differentiation, while none of the four cases of purely mucinous carcinoma had evidence of amplification. While the total number of cases in the study was limited, it would appear from the trend demonstrated by the data that protooncogene amplification (particularly c-myc) may be involved in the pathogenesis of aggressive common epithelial tumors of the ovary.

Adenocarcinoma, Mucinous↗
PubMed1989

Amplification of the proto-oncogenes int-2, c-erb B-2 and c-myc in human breast cancer.

int-2 is a proto-oncogene that is partially homologous to angiogenesis-inducing fibroblast growth factor and is believed to play a role in mouse mammary carcinogenesis. Recent evidence has suggested that this proto-oncogene may also play a role in human breast cancer. In the present study, we used Southern hybridization analysis to examine DNA from 79 primary and 11 recurrent human breast cancers for evidence of activation of int-2 through either gene rearrangement or amplification. A similar analysis was performed for two other proto-oncogenes, c-erbB-2 and c-myc, also suspected of playing a role in the development of human breast cancer. Proto-oncogene status was correlated with estrogen (ER) and progesterone (PR) receptor status, patient age, and lymph node (LN) status at the time of surgery. Gene rearrangement was not a frequent occurrence with any of the proto-oncogenes. However, amplification of int-2 occurred at a significantly higher frequency in recurrent breast cancers than in primary cancers and in patients with primary cancers who were less than or equal to 50 years of age versus greater than 50 years of age at surgery. Although amplification of all three proto-oncogenes occurred at a greater frequency in primary tumors from patients with lymph node metastases than from those without lymph node metastases, a significant difference was noted only in the case of c-myc amplification. These findings confirm and extend earlier results of studies of int-2, c-erbB-2 and c-myc amplification in human breast cancers and point to a role for int-2 activation in certain cases of recurrent breast malignant neoplasia.

Breast Neoplasms↗
PubMed1986

Oncogenes.

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Animals↗
PubMed1986

Di-n-octyl phthalate (DOP), a relatively ineffective peroxisome inducing straight chain isomer of the environmental contaminant di(2-ethylhexyl)phthalate (DEHP), enhances the development of putative preneoplastic lesions in rat liver.

Di-n-octyl phthalate (DOP) is the straight chain isomer of di(2-ethylhexyl) phthalate (DEHP) which is a widely used plasticizer and an environmental contaminant. DEHP is a strong inducer of peroxisome proliferation in rat liver. This is significant since other compounds which are strong inducers of peroxisome proliferation have been reported to be weak carcinogens (Reddy, J.K. and Lalwani, N.D., CRC Crit. Rev. Toxicol., 12 (1983) 1). In contrast to DEHP, DOP causes little or no induction of liver peroxisomes (Mann, A.H. et al., Toxicol. Appl. Pharmacol., 77 (1985) 116, and Gray, T.J.B. et al., Toxicology, 28 (1983) 167). In the current study the ability of 1% DOP to promote the development of putative preneoplastic lesions was evaluated. The effect of feeding 0.5% DEHP as well as equimolar amounts of its 2 major metabolites, mono(2-ethylhexyl)phthalate (MEHP) and 2-ethylhexanol (2-EH) were also investigated. GGT+ foci were initiated in the livers of Sprague--Dawley male rats with a single dose of diethylnitrosamine (DEN) following partial hepatectomy. The control group of rats was fed a semipurified diet (Co) for 10 weeks while the experimental groups received the semipurified diet containing the respective compounds. Induction of peroxisome proliferation was monitored by carnitine acetyltransferase (CAT) levels. DOP treatment resulted in a 6-fold increase in the number of GGT+ foci (20.8 +/- 4.0 vs. 3.5 +/- 1.3; P less than 0.05). This was accompanied by no change in liver weight and only a slight increase in CAT activity when compared with control animals. In contrast to DOP, 2-EH produced essentially no effect with regard to number of foci, peroxisome proliferation or liver weight. DEHP and MEHP induced significant peroxisome proliferation and hepatomegaly but the number of foci were significantly lower than in 2-EH-treated rats. The mechanism for the promoting ability of DOP is not clear but would not appear to be related to peroxisome proliferation. Because of the close similarity of chemical structure and metabolism between DOP and DEHP, it is possible that studies to define the mechanism of DOP induced promotion might also serve to further clarify the mechanism of DEHP induced carcinogenesis.

Animals↗
PubMed1985

Concentration-dependent inhibition of development of GGT positive foci in rat liver by the environmental contaminant di(2-ethylhexyl) phthalate.

The ability of di(2-ethylhexyl) phthalate (DEHP), a widely used plasticizer and environmental contaminant, to suppress development of putative preneoplastic lesions in rat liver was evaluated. gamma-Glutamyl transpeptidase-positive (GGT+) foci were initiated in the livers of Sprague-Dawley male rats with a single dose of diethylnitrosamine (DEN) following partial hepatectomy. Promotion of foci was commenced by feeding a choline-deficient diet (CD). A group of control rats was fed a choline-supplemented diet (CS). The ability of DEHP to suppress the emergence of GGT+ foci was evaluated by feeding additional groups of rats the CD diet containing either 0.1%, 0.5%, 1.0% or 2.0% DEHP. The CD diet promoted the number of GGT+ foci above levels in control livers. Inclusion of the plasticizer to the levels of 0.5%, 1.0% and 2.0% in the CD diet effectively inhibited the appearance of the foci. However, DEHP was unable to inhibit the promoting effect of the CD diet at a concentration of 0.1%. DEHP's ability to block development of GGT+ foci correlated with its ability to increase liver weight and to induce carnitine acetyltransferase (EC 2.3.1.7), a marker of peroxisome proliferation.

Animals↗
PubMed1985

Phosphorylation of specific rat plasma membrane proteins during promotion of gamma-glutamyl transpeptidase-positive hepatic foci and inhibition by di(2-ethylhexyl)phthalate.

The protein kinase activity of isolated plasma membranes from the livers of rats treated with three promoting regimens was examined using both exogenous proteins and endogenous plasma membrane proteins as substrates. Male rats first received either an initiating dose (30 mg/kg) of the hepatocarcinogen diethylnitrosamine or the 0.9% NaCl solution vehicle by i.p. injection at 18 h following partial hepatectomy. Ten days later, the three promoting regimens were begun. These consisted of 10 weeks of treatment with either (a) a choline-deficient (CD) diet, (b) a choline-supplemented (CS) diet containing 0.06% phenobarbital (PHB) (CS plus PHB), or (c) a CD diet containing 0.06% PHB (CD plus PHB). In addition, two other groups of rats received either (a) a CS diet containing 2% di(2-ethylhexyl)phthalate (DEHP) (CS plus DEHP) or (b) a CD diet containing 2% DEHP (CD plus DEHP). DEHP is a widely used plasticizer and environmental contaminant which we have shown previously inhibits the development of putative preneoplastic gamma-glutamyl transpeptidase (GGT) positive foci in rat liver. Total liver plasma membrane protein kinase activity using both protamine sulfate and histone was cyclic adenosine 3':5'-monophosphate independent and did not appear to be a marker of promotion. Its activity was increased by both DEHP which suppresses the development of GGT positive foci and a CD diet which promotes the appearance of GGT positive foci. The CD, CS plus PHB, and CD plus PHB dietary regimens, which promote the appearance of GGT positive foci, induced the phosphorylation of a Mr 40,000 plasma membrane protein in vitro by endogenous protein kinases. Plasma membranes from DEHP-treated rats did not demonstrate phosphorylation of this Mr 40,000 protein. DEHP dietary treatment also blocked the ability of epidermal growth factor to enhance the phosphorylation of its Mr 175,000 receptor protein in isolated liver plasma membranes. These results suggest that the phosphorylation of a Mr 40,000 plasma membrane protein may be important to the early promotional phase of liver carcinogenesis, and that one mechanism by which DEHP inhibits the emergence of GGT positive foci may be by blocking the response of initiated cells to stimulation by epidermal growth factor.

Animals↗
PubMed1985

Influence of dietary tryptophan on the induction of gamma-glutamyltranspeptidase-positive foci in the livers of rats treated with hepatocarcinogen.

The ingestion of an elevated level (2%) of L-tryptophan (TRP) in a purified diet was investigated to determine whether it would influence the induction of gamma-glutamyltranspeptidase (GGT)-positive foci in the livers of rats exposed to a hepatocarcinogen. Subtotal hepatectomies were performed, and 18 h later, the rats were given injections i.p. of diethylnitrosamine (30 mg/kg). Ten days later, groups of male rats were placed on choline-supplemented (CS), CS + TRP, choline-deficient (CD), or CD + TRP diets for 10 wk. In two separate experiments, the rats fed the CS + TRP diet or the CD diet developed more and larger GGT + foci than did rats fed the CS diet. Rats fed the CD + TRP diet revealed similar changes to those found in rats fed the CD diet. The liver weights of the rats fed the CD or the CD + TRP diet were greater than those of rats fed the CS or the CS + TRP diet. Hepatic GGT activity was somewhat elevated in rats fed the CS + TRP diet and markedly elevated in rats fed the CD or the CD + TRP diet. Hepatic ornithine decarboxylase activity was increased in rats fed the CD + TRP diet. The results suggest that increased dietary tryptophan has a promoting effect on liver carcinogenesis as measured by the induction of GGT + foci in the livers of rats exposed to diethylnitrosamine. A potentiating effect by tryptophan was not observed in the livers of rats fed a CD diet.

Amino Acids↗
PubMed1985

Disseminated talc granulomatosis. An unusual finding in a patient with acquired immunodeficiency syndrome and fatal cytomegalovirus infection.

The association of disseminated magnesium silicate talc granulomatosis and acquired immunodeficiency syndrome is reported in a male homosexual who used intravenous drugs and who died of overwhelming cytomegalovirus (CMV) infection. Autopsy findings included widespread deposition of talc crystals in the lungs, liver, lymph nodes, bone marrow, and spleen. Typical CMV inclusions were seen in the lungs, kidneys, adrenal glands, gastrointestinal tract, and right eye. There was no evidence of malignancy. Analysis of peripheral blood neutrophil function revealed impaired chemotaxis and chemokinesis, but opsonophagocytosis had remained normal. The CMV infection in the small bowel was extensive and resulted in severe destruction of the muscularis propria and neural plexi, leading to marked dilatation and persistent diarrhea. The terminal course was marked by intractable hypotension, pneumonitis, and malnutrition, which could be attributed respectively to CMV involvement of the adrenal glands, lungs, and small bowel. The etiology and possible role of systemic talc granulomatosis in the development of immunosuppressive illness is reported herein.

Acquired Immunodeficiency Syndrome↗
PubMed1984

Inhibition of phenobarbital and dietary choline deficiency promoted preneoplastic lesions in rat liver by environmental contaminant di(2-ethylhexyl)phthalate.

The effect of di(2-ethylhexyl)phthalate (DEHP), a widely used plasticizer and environmental contaminant, on the emergence of gamma-glutamyltranspeptidase positive (GGT+) preneoplastic foci in the liver of rats fed promoting diets was studied. GGT+ foci were initiated in the liver of Sprague--Dawley male rats with a single dose of diethylnitrosamine (DEN) following partial hepatectomy. One series of control rats received saline vehicle alone. Promotion of foci was commenced by feeding: (1) a choline-deficient diet (CD); (2) a choline-supplemented diet (CS) containing 0.06% phenobarbital (CS + PHB); or (3) a CD diet containing 0.06% phenobarbital (CD + PHB). In the absence of initiation by DEN, dietary treatments did not increase the number of GGT+ foci. In rats receiving DEN, each promoting regimen effectively increased the number of GGT+ foci above levels in control rats fed only the choline-supplemented diet. Inclusion of the plasticizer at a level of 2% in each of the dietary promotion treatments, however, effectively inhibited the appearance of the foci.

Animals↗
PubMed1984

Effect of tryptophan on informosomal and polyribosome-associated messenger RNA in rat liver.

The possible role that informosomal mRNA may play in the stimulation of hepatic protein synthesis induced by the acute administration of tryptophan was investigated. L-tryptophan (30 mg/100 g body weight) tube-fed to rats induced an increase (20%) in the amount of polyribosome-associated poly(A+)mRNA in the liver within 1 hour. On the other hand, the amount of the informosomal poly(A+)- mRNA revealed no significant increase or decrease. The size of the increase in the polyribosome-associated poly(A+)mRNA pool was equal to the entire amount of informosomal poly(A+)mRNA present in the hepatic cells. Therefore it was concluded that the failure to detect a significant decrease in the size of the informosomal mRNA pool indicated that the increase in the polyribosome-associated poly(A+)mRNA must be due to a different mechanism, such as enhanced nuclear-to-cytoplasmic translocation of nuclear poly(A+)mRNA, which had been reported earlier. To determine whether any qualitative or quantitative changes occurred in the RNA sequences along with the increase in poly(A+)mRNA following tryptophan administration, DNA/RNA hybridization studies were conducted by using hepatic polyribosome-associated poly(A+)- mRNA from tryptophan-treated and control rats. Although qualitatively no new species of mRNA were detected in the mRNA from tryptophan-treated rats, kinetic analysis of the hybridization curves indicated that there was a shift or accumulation of hepatic poly(A+)mRNA belonging to the intermediate and possibly the high frequency classes of polyribosome-associated poly(A+)mRNA in the livers of the tryptophan-treated rats.

Animals↗
PubMed1983

Inhibition of development of preneoplastic lesions in the livers of rats fed a weakly carcinogenic environmental contaminant.

The effects of di(2-ethylhexyl)phthalate (DEHP), a widely used plasticizer and environmental contaminant, on the emergence of gamma-glutamyltrans-peptidase positive (GGT+) preneoplastic foci in the liver was investigated. Sprague--Dawley male rats initiated with diethylnitrosamine (DEN) following partial hepatectomy were placed on: (1) a choline supplemented diet (CS); (2) a CS diet containing 2% DEHP (CS + DEHP); (3) a choline deficient diet (CD); (4) a CD diet containing a 0.06% phenobarbital (CD + PHB); or (5) a CD diet containing 2% DEHP (CD + DEHP). Rats maintained on the CS + DEHP diet for 5 and 10 weeks showed no increase in GGT + foci. The plasticizer effectively inhibited the appearance of the preneoplastic foci when it was included with the CD diet.

Animals↗
PubMed1976

Dual labeling in standard DNA-RNA hybridization studies using 125 I-labeled nuclear RNA and 3H-labeled DNA.

Standard DNA-RNA hybridization studies, using nucleic acids isolated from mammalian tissues, are frequently hindered by relatively low levels of radioactivity in pulse-labeled RNA and in an inability to reliably estimate the amount of DNA present in the hybrid. In the method described here nuclear RNA is labeled in vitro with 125I to 400 000- 800 000 cpm/mug and DNA is obtained from a rat glial tumor line grown in culture and labeled to specific activities of 42 000-79 000 cpm/mug. DNA-RNA hybridization is conducted in an all solution system at RNA:DNA ratios of 3.5:1 to 18:1. Assay background is controlled by pretreatment of the hybrid and free RNA at the conclusion of the annealing study with RNase, then isolation of the hybrid together with a small fraction of free RNA oligonucleotides on hydroxyapatite. The partially purified hybrids are then trapped on Millipore filters. Assay background id 0.004% of total counts present in the annealing reaction. Comparison of the annealing reactions of pulse-labeled liver nuclear RNA and in vitro 125I-labeled nuclear RNA in saturation, kinetic, and competitive hybridization studies shows them to be essentially the same. Nuclear RNA labeled by either tritium or iodine shows a 10-20-fold greater concentration of the annealing sequences over that found in the microsomal RNA. Minor differences are noted between the nuclear RNAs in the initial rates of reaction and in the magnitude of the decrease in percent hybridization at low levels of unlabeled competitor RNA. This may be due to preferential labeling in pulse-labeled RNA of molecules which are present in lower concentrations or are transcribed from more frequently repeated DNA sequences than the average population of annealing RNA molecules. The technique has application in systems where the amount of tissue for RNA extraction is small or where the system does not permit the obtaining of pulse-labeled RNA, as in experimental rodent skin carcinogenesis or in dealing with RNA from the tissues of large mammals or humans.

Animals↗