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E Adam

Publications and source records attributed to E Adam.

At least 19 recordsLinked to original sources
PubMed1996

The CREB, ATF-1, and ATF-2 transcription factors from bovine leukemia virus-infected B lymphocytes activate viral expression.

Efficient transcription and replication of the bovine leukemia virus (BLV) genome require both the viral long terminal repeat (LTR) and the virus-coded transcriptional activator Tax, which functions through a 21-bp sequence (Tax-responsive element [TxRE]) which is repeated three times within the LTR. Since Tax does not bind directly to DNA, host cell transcription factors play a central role in BLV expression. Electrophoretic mobility shift assays with nuclear extracts prepared with infected bovine B lymphocytes revealed five TxRE-specific complexes (C1, C2, C3, C4, and C5). Here, by using a UV-induced indirect labeling technique (UV cross-linking) in conjunction with mobility shift assays, eight major polypeptides of 31, 33, 42, 46, 51, 57, 87, and 119 kDa were identified within these five complexes. Immunoprecipitation experiments identified the 57- and 119-kDa proteins as cyclic AMP response element-binding (CREB) proteins, the 46- and 51-kDa proteins as activating transcription factor-1 (ATF-1), and the 87-kDa as protein ATF-2. All of these proteins (except the ATF-1 protein of 51 kDa) belong to the complex C1, which is the major complex identified in freshly isolated BLV-infected lymphocytes from cattle with persistent lymphocytosis. In transient-cotransfection experiments, these three transcription factors were able to activate LTR-directed gene expression in the presence of protein kinase A or Ca2+/calmodulin-dependent protein kinase IV. CREB protein, ATF-1, and ATF-2 thus appear to be the major transcription factors involved in the early stages of viral expression.

Activating Transcription Factor 1↗
PubMed1996

Cellular pathways involved in the ex vivo expression of bovine leukemia virus.

Bovine leukemia virus (BLV) is the etiologic agent of enzootic bovine leukosis. The virus adopts a strategy based on the lack of viral expression in vivo; only very rare BLV-infected B lymphocytes express viral information. When the cells are isolated from animals in persistent lymphocytosis and cultivated ex vivo, a tremendous increase in viral expression occurs. To gain insight into this mechanism, we employed a general approach using chemicals that interfere specifically with cellular pathways involved in signal transduction from the cell membrane to the nucleus. Our data demonstrate that BLV expression is not correlated with the activity of protein kinase A (PKA) and is even inhibited by cyclic AMP (cAMP). The cAMP/PKA pathway is thus apparently not involved in ex vivo viral expression. In contrast, PKC appears to play a key role in this process. Phorbol myristate acetate can directly activate viral expression in B cells (in the absence of T cells). Furthermore, calphostin C, a highly specific inhibitor of PKC, partly decreases ex vivo BLV expression. Our data further demonstrate that calmodulin and calcineurin, a calmodulin-dependent phosphatase, play a key role in the induction of viral expression. The involvement of this calmodulin-dependent pathway could explain the induction of expression that cannot be assigned to PKC. Furthermore, it appears that the activation of viral expression requires a calmodulin but not a PKA-dependent pathway. These data highlight major differences between transient transfection and ex vivo experiments. Finally, despite their homologies, BLV and human T-cell leukemia virus appear to use different signal transduction pathways to induce viral expression.

Animals↗
PubMed1995

Cytomegalovirus and atherosclerosis.

Finding that an avian herpesvirus can cause atherosclerosis in chickens prompted studies of human herpesviruses in human atherosclerosis. Antigens and nucleic acid sequences of cytomegalovirus (CMV), a widespread member of the herpesvirus family, were found in arterial lesions in human atherosclerosis, but infectious virus has not been observed. In atherosclerosis patients, high levels of CMV antibodies are present, suggesting the presence of virus that had been activated from a latent state. Atherosclerosis also develops in immune-suppressed heart transplant patients infected with CMV. The properties of CMV are consistent with its involvement at several levels of the atherogenic process. If this concept is correct, immunization with a CMV vaccine should prevent CMV infection and atherosclerosis.

Arteriosclerosis↗
PubMed1995

Transcription of tobacco phytochrome-A genes initiates at multiple start sites and requires multiple cis-acting regulatory elements.

Promoter regions of the Nicotiana tabacum PHYA1 and PHYA2 genes display 89% sequence identity. Analysis of the 5' ends of both the PHYA1 and the PHYA2 transcript revealed multiple, distinct mRNA species, each differing in length and in abundance. The levels of the major PHYA1, PHYA2 transcripts were found to be auto-regulated by phytochrome. This auto-regulation was most efficient in 2-8-day old seedlings. Furthermore, we examined the expression pattern of the PHYA1-GUS reporter gene, containing a 4700 bp PHYA1 promoter fragment or its 5'-deletion derivatives, by GUS histochemistry and by RNase protection assays in transgenic tobacco plants. Our data indicate that the PHYA1 promoter contains three regions which are necessary for the maximum level and regulated expression. We show that a 264 bp promoter fragment contains a cis-regulatory element(s) responsible for expression in the root tips of transgenic seedlings. The major cis-regulatory elements required for high-level transcription and expression in other organs are located in separate regions of the PHYA1 promoter. These data indicate the contribution of multiple cis-regulatory elements for the maximum and regulated expression of tobacco genes coding for phytochrome A protein.

Base Sequence↗
PubMed1995

Molecular characterization and expression of a tobacco histone H1 cDNA.

We have isolated a 1104 bp tobacco cDNA clone (H1c12) which includes an 846 bp open reading frame. This encodes a polypeptide of 282 amino acid residues and represents the largest plant H1 histone identified so far. The structure of the deduced protein shows the classical tripartite organization of the H1-type linker histones. The expression of the tobacco H1 histone gene(s) corresponding to the H1c12 cDNA clone was examined during different developmental stages. We found that, at the level of steady-state mRNA, expression of gene(s) encoding this H1 histone was rapidly induced in germinating seeds. The H1 gene was expressed in all tissues examined. However, its expression was higher in tissues known to contain meristematic cells. Furthermore, in the leaves of mature plants accumulation of the H1 mRNA exhibits a very characteristic oscillation. This latter finding indicates that, at least in fully developed plants, the expression of this type of H1 histone gene(s) is modulated by a diurnal cycle.

Amino Acid Sequence↗
PubMed1995

Biochemical, histochemical and cell biological investigations on the actions of mistletoe lectins I, II and III with human breast cancer cell lines.

Cytotoxicity of the mistletoe lectins I, II and III towards six human breast cancer cell lines was assessed using the Mossman assay. In addition, binding of the three mistletoe lectins to the separated membrane glycoproteins of these cell lines, the binding and uptake of these lectins into the cells in tissue culture and the binding of the lectins to histological preparations of these cell lines were analysed. The results indicate that there are quantitative differences concerning the toxicity of these three lectins towards the different cell lines. Furthermore, the lectin binding pattern in the cell lines differed. In Western blots, several membrane glycoproteins were labelled by the lectins. Our results indicate subtle differences between the three lectins with regard to the parameters mentioned above; however, the toxicity of all three lectins from mistletoe is so similar that they all seem suitable for the construction of immunotoxins.

Breast Neoplasms↗
PubMed1995

Sex-steroid control of galanin in the rat hypothalamic-pituitary axis.

To further investigate how sex steroids regulate galanin (GAL) in the rat pituitary and hypothalamus, we examined the effects of prepubertal gonadectomy (Gx) and long-term (9 weeks) replacement with estradiol (E2) or testosterone (T) on pituitary and hypothalamic GAL concentrations in Wistar rats (5-6/group). Sham-operated animals served as controls (CTR). Pituitary GAL concentration was markedly higher in random-cycling CTR-females than in CTR-males (1391 +/- 247 vs 39 +/- 5 pg/mg protein, P < 0.01) and decreased after Gx only in females (20 +/- 3 pg/mg protein, P < 0.01). E2 strongly increased pituitary GAL in Gx-females and Gx-males (4470 +/- 365 and 3853 +/- 347 pg/mg protein, P < 0.01), whereas T had no effect. Inversely, hypothalamic GAL was higher in CTR males than in CTR females (5.4 +/- 0.3 vs 4.0 +/- 0.5 ng/mg protein, P < 0.05), and decreased significantly after gonadectomy in males (3.7 +/- 0.2 ng/mg protein, P < 0.01). The only steroid treatment that significantly modified hypothalamic GAL in Gx animals was administration of E2 to females (5.7 +/- 0.4 ng/mg protein, P < 0.01 vs non-treated Gx). We also studied in hypophysectomized (Hx) rats (8/group) the effects of sex steroids on hypothalamic GAL concentration and distribution. The low hypothalamic GAL concentration observed in male and female Hx rats (1.0 +/- 0.1 ng/mg protein) was significantly increased by T in males and in females (respectively, by 40% and by 50%, P < 0.02) and by E2 in males (by 60%, P < 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Lectin-binding properties of human breast cancer cell lines and human milk with particular reference to Helix pomatia agglutinin.

Several studies have shown binding of a variety of lectins to breast cancer cells in tissue sections. In particular, binding of the lectin from the Roman snail, Helix pomatia agglutinin (HPA), to breast cancer cells is linked with a poor prognosis. The molecular basis for lectin binding to metastatic breast cancers is not known. To elucidate this in a model system, lectin-binding patterns of seven human breast cancer cell lines were investigated, their cell membranes were isolated, and HPA binding was assessed. In addition, the influence of fixation and processing on lectin-binding sites was also investigated. Binding of lectins to the tumor cells was very heterogeneous between and within the different cell lines and was influenced by fixation and processing. However, some cell lines showed HPA-binding sites both in vivo and in tissue sections. Analysis of the isolated cell membrane glycoproteins from these cell lines on Western blots revealed that HPA can bind to several membrane glycoproteins. In contrast, human milk shows only one major milk glycoprotein that is HPA-positive. Therefore, a switch in glycosylation appears to be taking place during the transformation to a metastatic phenotype.

Animals↗
PubMed1995

Reduced liver insulin-like growth factor-I gene expression in young zinc-deprived rats is associated with a decrease in liver growth hormone (GH) receptors and serum GH-binding protein.

Zinc depletion attenuates growth and decreases circulating IGF-I. To investigate the mechanisms responsible for the IGF-I decline, we determined the effects of dietary zinc (Zn) deficiency on body and organ growth, serum IGF-I, serum GH-binding protein (GHBP), liver GH receptors and liver expression of their corresponding gene. After 1 week of adaptation to a normal zinc diet, a zinc-deficient diet (ZD; Zn, 0 p.p.m.) or a zinc-normal diet (CTR; Zn, 75 p.p.m.) was available ad libitum to 4-week-old Wistar rats for 4 weeks. Pair-fed animals (PF) received the zinc-normal diet in the same absolute amount as that consumed the day before by the ZD group. The food intake of ZD and PF rats was reduced by 32% (P < 0.001) compared with the CTR group. Zinc depletion specifically reduced body weight gain (-22%, P < 0.05), serum IGF-I concentrations (-52%, P < 0.001), hepatic GH receptors (-28%; P < 0.05) and serum GHBP levels (-51%; P < 0.05), compared with the PF group. GH concentrations were reduced in ZD animals compared with CTR rats (P < 0.01). The caloric restriction of PF animals also decreased body weight gain (-50%, P < 0.001), serum IGF-I concentrations (-21%, P < 0.05), liver GH receptors (-38%, P < 0.001) and serum GHBP levels (-38%, P < 0.01), when compared with the CTR group. Both ZD and PF groups had reduced liver IGF-I and GH receptor/GHBP mRNA levels in comparison with the CTR group (P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Colposcopically directed biopsy and loop excision of the transformation zone. Comparison of histologic findings.

We performed a retrospective comparison between the findings from colposcopically directed biopsies and those from loop excision of the transformation zone (LETZ) specimens. The correlation was satisfactory. When a low grade squamous intraepithelial lesion (SIL) was predicted on a cytologic smear and biopsy specimen, no cases of invasive carcinoma were found. In two (0.8%) cases in which a high grade SIL was predicted on the cervical smear and biopsy, microinvasive carcinoma was found in the LETZ specimen.

Adolescent↗
PubMed1994

Cytomegalovirus/herpesvirus and carotid atherosclerosis: the ARIC Study.

Ubiquitous viruses such as members of the human herpes virus group, particularly cytomegalovirus (CMV), have been proposed to be clinically important agents in the initiation and progression of atherosclerosis. Antibodies to CMV and herpes simplex virus type 1 (HSV1) and type 2 (HSV2) were determined in 340 matched case-control pairs from the Atherosclerosis Risk in Communities (ARIC) Study. Cases were defined by B-mode ultrasonography as persons with thickened carotid artery walls consistent with early atherosclerosis but without a history of cardiovascular disease. Controls were defined as persons without thickened walls or history of cardiovascular disease. The case-control odds ratio for CMV antibodies was 1.55 (P = .03), for HSV 1.41 (P = .07), and for HSV2 0.91 (P = .63). When adjustment was made for potential confounders, the odds ratios were 1.36 for CMV (P = .24), 1.21 for HSV1 (P = .45), and 0.61 (P = .05) for HSV2. These results suggest a modest association between CMV and asymptomatic carotid wall thickening consistent with early atherosclerosis.

Antibodies, Viral↗
PubMed1994

Cytomegalovirus DNA in arterial walls of patients with atherosclerosis.

The biological properties of cytomegalovirus (CMV) are consistent with a potential role in the pathogenesis of atherosclerosis. The evidence of such a role has so far been circumstantial, but CMV nucleic acid is beginning to be reported with increasing frequency in the arterial wall. Arterial specimens from 135 patients who underwent vascular surgery for symptomatic atherosclerotic vessel disease were analyzed by PCR for the presence of CMV nucleic acid. Samples were studied from the atheromatous plaque area and from uninvolved aortic tissues of patients undergoing surgery for vascular disease. One primer pair (LA) was used for detection of a late gene, and two other primer pairs (E1 and E2) were used for the immediate early gene region. Serum antibody to CMV was measured by radioimmunoassay. With the late gene primer, CMV nucleic acid was found in 76% of the tissue specimens tested, whereas the E2 gene primer complementary to the transforming mtr2 region was reactive in 90% of the arterial samples. There was no significant difference in the prevalence of CMV DNA in atherosclerotic plaque tissue and in uninvolved aortic tissue from the patients. A second early gene primer was not reactive with the tissue specimens, although it gave positive results with the positive control of infectious virus. Serum antibody to CMV was detected in 86% of the patients in whose tissue CMV DNA was demonstrated. CMV DNA was detected in a high proportion of atherosclerotic plaque tissues as well as in uninvolved aortic tissue of surgical patients, suggesting that latent CMV infection of the arterial wall may be a common occurrence in patients with atherosclerosis.

Adult↗
PubMed1994

Second primary cancer arising from the neovulva following reconstruction with myocutaneous flaps.

Myocutaneous flaps have been used for vulvar reconstruction following radical vulvectomy. For over 15 years the most common complications related to these flaps are sloughing of the skin and donor site wound infection. A new malignancy arising from the skin of the neovulva is an unusual occurrence. Two cases are presented. The skin of the neovulva may be exposed to the same neoplastic carcinogens that caused the initial lesion. In both patients, the polymerase chain reaction method failed to detect the presence of human papillomavirus DNA in either the initial lesion or the recurrent cancer.

Aged↗
PubMed1994

Glycosylation patterns of the human colon cancer cell line HT-29 detected by Helix pomatia agglutinin and other lectins in culture, in primary tumours and in metastases in SCID mice.

Human colonic cancer cells (HT-29, 10(7) cells/dose) were injected subcutaneously between the scapulae of 19 severe combined immunodeficient (SCID) mice. After 19 days, large tumours had developed in 18 out of the 19 animals and the mice were then killed. Metastases were detected in the lungs of 16 animals but not in other organs investigated. Surgical removal of the primary tumour in another group of five animals led to a prolonged survival and further growth of metastases in the lungs. HT-29 injection into the tail vein (n = 5) resulted in colonization of the lungs. The tumours that developed in the animals were signet cell carcinomas; these forms are not seen in HT-29 cells in culture. Glycoconjugate expression of the tumours was assessed using several lectins. In many cases the results indicated a stability of lectin-binding patterns from cell culture conditions to implantation into the SCID mice. This was true for the lectin Helix pomatia agglutinin (HPA), the binding of which is associated with a high metastatic potential in some human tumours, including colon cancer. All the primary tumours and metastases were HPA positive. This xenograft tumour model seems to be a clinically relevant system for the study of glycoconjugate expression in human colon cancer cells and their metastases.

Animals↗
PubMed1994

Expression of interleukin 6 receptors and interleukin 6 mRNA by bovine leukaemia virus-induced tumour cells.

Bovine leukaemia virus (BLV) is the aetiologic agent of bovine leucosis. The virus induces malignancies of the B-cell lineage (leukaemia/lymphoma). The role played by interleukin 6 (IL-6) in the BLV-induced leukemogenesis process was evaluated. Six cell lines derived from BLV-induced tumours were tested for the expression of IL-6 receptors. Two cell lines (LB155 and YR2) display 250-300 receptor per cell (kd = 1.7 10(-10) M and 1.4 10(-10) M, respectively) whereas the other four (LB159, LB167, YR1 and M51) do not display detectable amounts of receptors. Very low (if any) expression of IL-6 receptors has been found in the case of the B lymphocytes of animals in persistent lymphocytosis (PL). Despite the presence of IL-6 receptors on the surface of LB155 and YR2 cells, no influence of exogenous IL-6 on their growth has been observed. Northern analyses indicated the presence of IL-6 transcripts only in the case of mRNA isolated from LB155 cells. Since this cell line also expresses receptors for the cytokine, an autocrine loop may exist in these cells. Experiments in which bovine and bovine epithelial cell lines were transfected with a plasmid containing the bovine IL-6 promoter controlling the expression of the reporter cat gene failed to indicate any influence of the viral transactivator p34tax on the activity of this promoter. We conclude that IL-6 receptors and IL-6 mRNA can be found in some BLV-induced tumours, but this does not correlate with viral expression in BLV-induced leukaemia/lymphoma.

Animals↗
PubMed1994

Binding patterns of mistletoe lectins I, II and III to microglia and Alzheimer plaque glycoproteins in human brains.

Glycoconjugates of microglial cells and in some cases those glycoconjugates present in the amyloid plaques in Alzheimer's disease in the cerebral cortex can be stained with a lectin from mistletoe (ML-I) using a labour-intensive and time-consuming indirect immunoperoxidase technique. In order to simplify the staining method and to test the staining characteristics of the other recently isolated mistletoe lectins (ML-II, ML-III) biotinylated MLs I-III were used together with an avidin-alkaline phosphatase-complex for visualisation. Our findings indicate that this new improved technique can also be used for detection of microglial cells and is considerably faster than the old method. In addition to microglial cells, ML-I labelled plaque glycoproteins possibly indicating that glycoconjugates derived from microglia can be detected in plaques. In contrast to ML-I, both ML-II and ML-III did not stain microglial cells.

Alzheimer Disease↗
PubMed1994

Involvement of the cyclic AMP-responsive element binding protein in bovine leukemia virus expression in vivo.

The TAR element (Tax-responsive element; also called TxRE) is a major determinant of the regulation of bovine leukemia virus (BLV) expression. In order to gain insight into the mechanisms of viral expression, complexes formed between proteins and the TAR enhancer DNA were analyzed by gel retardation assays. We report here that nuclear lysates from ex vivo-isolated B lymphocytes contain proteins that specifically bind to TAR. An antibody directed toward the cyclic AMP-responsive element binding (CREB) protein supershifted a complex (C1) present only in BLV-infected B lymphocytes. The CREB protein thus appears to be a major transcription factor involved in BLV expression in vivo.

Animals↗