Biomedical subjects

S M Anderson

Publications and source records attributed to S M Anderson.

At least 73 records · Page 4Linked to original sources

PubMed1997

Transduction efficiency of cell lines and hematopoietic stem cells correlates with retrovirus receptor mRNA levels.

The low transduction efficiency of hematopoietic stem cells (HSC) using amphotropic retroviruses continues to plague gene therapy protocols. This low transduction efficiency may be related to a low level of amphotropic retrovirus binding to target cell receptors. We have assayed murine and human cell lines as well as primary bone marrow HSC populations for mRNA encoding retrovirus receptors. Total cellular RNA was amplified by reverse transcriptase-polymerase chain reaction and the level of ecotropic and amphotropic receptor mRNA was compared to the level of beta 2-microglobulin mRNA in the same cell populations. Cell lines that are easily transduced by ecotropic and amphotropic retroviruses have high levels of receptor mRNA. In studies using murine HSC-enriched populations obtained from bone marrow, we observed a high correlation between transduction efficiency and the level of ecotropic and amphotropic receptor mRNA. We predict from these findings that purification of monkey and human HSC populations with high levels of amphotropic receptor mRNA will enable us to obtain improved efficiency of gene transfer.

3T3 Cells↗

PubMed1997

Developmental outcomes of children with myelomeningocele: prenatal predictors.

OBJECTIVE: The purpose of the current investigation was to determine cognitive developmental outcomes for a cohort of children with prenatally detected myelomeningocele and to determine whether the variables of (1) severity of ventriculomegaly and (2) anatomic level of lesion were predictive of cognitive development. STUDY DESIGN: Prenatal ultrasonographic examinations were reviewed by a single perinatologist to determine the degree of ventriculomegaly and the anatomic level of the lesion. Ventriculomegaly was defined as a lateral ventricular atrial width > 10 mm. Anatomic level of lesion was defined as (1) thoracic, (2) high lumbar, (3) midlumbar, (4) low lumbar-high sacral, or (5) sacral. Cognitive developmental quotients for surviving children were determined by one of two developmental pediatricians with use of a modified version of the Clinical Adaptive Test/Clinical Linguistic Auditory Milestone Scale, a measure of visual-motor and language abilities. RESULTS: The mean cognitive developmental quotient for subjects with absent to mild ventriculomegaly was 90.3 (range 54 to 120, SD 17.4), whereas the mean cognitive developmental quotient for those with moderate to severe ventriculomegaly was 74.0 (range 65 to 100, SD 17.1) (p < 0.01). There was a negative correlation between the degree of ventriculomegaly and the cognitive developmental quotient (r = -0.43, p < 0.025) and a positive correlation between the level of the lesion and the cognitive developmental quotient (r = 0.50, p < 0.01). CONCLUSIONS: The degree of ventriculomegaly determined on high-resolution prenatal ultrasonography is predictive of early cognitive development in children with myelomeningocele, with worsening ventriculomegaly being associated with lower cognitive developmental quotients. The anatomic level of the lesion also has predictive value, with lower level lesions being associated with more favorable cognitive outcomes. However, because of the high degree of variance in developmental quotients within the two ventriculomegaly groups, we advise clinicians to use caution in the interpretation and use of our data.

Cerebral Ventricles↗

PubMed1997

Psyllium-enriched cereals lower blood total cholesterol and LDL cholesterol, but not HDL cholesterol, in hypercholesterolemic adults: results of a meta-analysis.

We conducted a meta-analysis to determine the effect of consumption of psyllium-enriched cereal products on blood total cholesterol (TC), LDL cholesterol (LDL-C) and HDL cholesterol (HDL-C) levels and to estimate the magnitude of the effect among 404 adults with mild to moderate hypercholesterolemia (TC of 5.17-7.8 mmol/L) who consumed a low fat diet. Studies of psyllium cereals were identified by a computerized search of MEDLINE and Current Contents and by contacting United States-based food companies involved in psyllium research. Published and unpublished studies were reviewed by one author and considered eligible for inclusion in the meta-analysis if they were conducted in humans, were randomized, controlled experiments, and included a control group that ate cereal providing </=3 g soluble fiber/d. Eight published and four unpublished studies, conducted in four countries, met the criteria. Analysis of a linear model was performed, controlling for sex and age. Female subjects were divided into two groups to provide a rough estimate of the effect of menopausal status (premenopausal = <50 y, postmenopausal = >/=50 y) on blood lipids. The meta-analysis showed that subjects who consumed a psyllium cereal had lower TC and LDL-C concentrations [differences of 0.31 mmol/L (5%) and 0.35 mmol/L (9%), respectively] than subjects who ate a control cereal; HDL-C concentrations were unaffected in subjects eating psyllium cereal. There was no effect of sex, age or menopausal status on blood lipids. Results indicate that consuming a psyllium-enriched cereal as part of a low fat diet improves the blood lipid profile of hypercholesterolemic adults over that which can be achieved with a low fat diet alone.

Adult↗

PubMed1997

Phosphorylation of cbl after stimulation of Nb2 cells with prolactin and its association with phosphatidylinositol 3-kinase.

Stimulation of Nb2 cells with PRL results in the rapid phosphorylation of a 120-kDa protein identified as the adapter protein cbl on tyrosine residues. Maximal phosphorylation of cbl occurs at 20 min after PRL stimulation and declines thereafter. Stimulation with as little as 5 nM PRL resulted in the phosphorylation of cbl; increasing the concentration of PRL to 100 nM had only a minimal effect upon the phosphorylation of cbl. The cbl protein appears to be constitutively associated with grb2 and the p85 subunit of phosphatidylinositol 3-kinase (PI 3-kinase). The constitutive association of cbl with the p85 subunit of PI 3-kinase was observed in Nb2 cells as well as in 32Dcl3 cells transfected with either the rat Nb2 (intermediate) form of the PRL receptor or the long form of the human PRL receptor. A glutathione S-transferase fusion protein encoding the SH3 domain of the p85 subunit of PI 3-kinase bound to cbl in lysates of both unstimulated and PRL-stimulated Nb2 cells; however, neither of the SH2 domains of p85 bound to cbl under the same conditions. PRL stimulation increased the cbl-associated PI kinase activity. The majority of PI kinase activity appeared to be cbl-associated after PRL stimulation. These results suggest that cbl may function as an adapter protein in PRL-mediated signaling events and regulate activation of PI 3-kinase. Our model suggests that the p85 subunit of PI 3-kinase is constitutively associated with cbl through binding of the p85 SH3 domain to a proline-rich sequence in cbl. After the tyrosine phosphorylation of cbl, an SH2 domain(s) of p85 binds to a specific phosphorylation site(s) in cbl, leading to the activation of PI 3-kinase.

Adaptor Proteins, Signal Transducing↗

PubMed1997

Interleukin-7R alpha mRNA expression increases as stem cells differentiate into T and B lymphocyte progenitors.

The gamma common (gamma c) chain is a partner in several interleukin receptor complexes, including the interleukin-2 receptor (IL-2R), IL-4R, and IL-7R. Mutations in the gamma c gene are associated with X-linked severe combined immunodeficiency (SCID). Using reverse transcriptase-PCR, we examined the level of mRNA-encoding gamma c and its partners in mouse pluripotent hematopoietic stem cells (PHSCs), which repopulate both bone marrow and thymus. We also assayed developing lymphocytes to define which, if any, IL-R complexes are expressed at the earliest stage of T and B lymphocyte maturation. RNA extracted from bone marrow-derived PHSCs did not contain detectable levels of mRNA-encoding IL-7R alpha. However, the most primitive (CD4- CD8-) T cells from the thymus and the most primitive (c-kit+ B220+) B cells from bone marrow contained high levels of IL-7R alpha mRNA. There were no detectable differences between PHSCs and primitive or more mature T and B cells for expression of gamma c mRNA. We conclude that the onset of IL-7R formation occurs at the earliest stage of differentiation of T and B lymphocytes. Our findings are consistent with the hypothesis that the absence of an intact IL-7R (IL-7R alpha and gamma c) may be a critical loss that interrupts lymphopoiesis.

Animals↗

PubMed1996

Over-expression of protein tyrosine phosphatase 1 (PTP1) alters IL-3-dependent growth and tyrosine phosphorylation.

Interleukin-3 (IL-3) is a hematopoietic growth factor receptor which stimulates the proliferation of multilineage progenitor cells. It is known that IL-3 stimulates tyrosine phosphorylation while transducing a mitogenic signal. The signal transduction pathways activated by the IL-3 receptor, however, are not fully understood. In this study a protein tyrosine phosphatase has been over-expressed in the IL-3 dependent, murine myeloid progenitor cell line, 32D cl3 in order to test whether altering the levels of tyrosine phosphorylation would change IL-3 stimulated proliferation. These cells were transfected with a metal-inducible expression vector containing a rat cDNA encoding PTP1. A low basal level of rat PTP1 message and protein was detected in cells transfected with the PTP1 vector, and zinc treatment resulted in a three- to fourfold increase in the amount of PTP1 message, protein and catalytic activity. Over-expression of PTP1 resulted in a two- to threefold decrease in IL-3 stimulated proliferation. Cells over-expressing PTP1 also exhibited decreased levels of tyrosine phosphorylation; phosphorylation of the IL-3 receptor beta subunit and the Shc protein were both dramatically decreased. Thus, PTP1 over-expression negatively modulated IL-3 signal transduction. To identify potential substrates of PTP1, 32D cl3 cells were transfected with a catalytically inactive PTP1 mutant, PTP1(C/S). Three tyrosine-phosphorylated proteins of MW 140, 79 and 69 k coprecipitated with PTP1(C/S). We believe that the 140 kDa protein represents the beta subunit of the IL-3 receptor. In addition, a GST-fusion protein containing active PTP1 dephosphorylated the beta-subunit in an in vitro assay. By immunofluorescent microscopy over-expressed PTP1(C/S) co-localized largely with calnexin, an endoplasmic reticulum-associated protein. Immunofluorescent microscopy also indicated that PTP1(C/S) and the beta subunit co-localized at discrete sites at the plasma membrane and around a cytoplasmic organelle where most of the beta subunit was located. These observations suggest PTP1 over-expression may down-regulate the growth response to IL-3 through dephosphorylation of the IL-3 receptor, perhaps in an intracellular compartment, thereby inhibiting propagation of the IL-3 mitogenic signal.

Animals↗

PubMed1996

The level of mRNA encoding the amphotropic retrovirus receptor in mouse and human hematopoietic stem cells is low and correlates with the efficiency of retrovirus transduction.

The low level of amphotropic retrovirus-mediated gene transfer into human hematopoietic stem cells (HSC) has been a major impediment to gene therapy for hematopoietic diseases. In the present study, we have examined amphotropic retrovirus receptor (amphoR) and ecotropic retrovirus receptor mRNA expression in highly purified populations of mouse and human HSC. Murine HSC with low to undetectable levels of amphoR mRNA and relatively high levels of ecotropic retrovirus receptor mRNA were studied. When these HSC were analyzed simultaneously for ecotropic and amphotropic retrovirus transduction, ecotropic provirus sequences were detected in 10 of 13 long-term repopulated animals, while amphotropic proviral sequences were detected in only one recipient. A second distinct population of murine HSC were isolated that express 3-fold higher levels of amphoR mRNA. When these HSC were analyzed simultaneously for ecotropic and amphotropic retrovirus transduction, 11 of 11 repopulated mice contained ecotropic provirus and 6 of 11 contained amphotropic provirus sequences, a significant increase in the amphotropic retrovirus transduction (P = 0.018). These results indicate that, among the heterogeneous populations of HSC present in adult mouse bone marrow, the subpopulation with the highest level of amphoR mRNA is more efficiently transduced by amphotropic retrovirus. In a related study, we found low levels of human amphoR mRNA in purified populations of human HSC (CD34+ CD38-) and higher levels in committed progenitor cells (CD34+ CD38+). We conclude that the amphoR mRNA level in HSC correlates with amphotropic retrovirus transduction efficiency.

Animals↗

PubMed1996

Analysis of the expression of glycosylphosphatidylinositol anchored proteins on platelets from patients with paroxysmal nocturnal hemoglobinuria.

Paroxysmal nocturnal hemoglobinuria (PNH), an acquired clonal disorder is manifested by failure of hematopoietic cells to express phosphatidylinositol glycan-anchored proteins (PIG-AP). Since the PIG-A mutation is present at the stem cell level, all cell lines may be affected. Although the pathogenesis of hemolytic anemia in PNH is related to the absence of CD55 and CD59 molecules on the membrane of red cells, the mechanism responsible for the increased incidence of thrombotic events in PNH is not clear. In this study we measured two glycosylphosphatidylinositol (GPI)-linked molecules on platelets (CD55 and CD59) and two GPI-linked proteins on neutrophils (CD14 and CD16), comparing their expression on normal and PNH patients. Using two-color flow cytometric analysis with antibodies directed against CD42b and CD41a, we found that CD55 and CD59 were constitutively expressed by normal fresh platelets, but that the expression levels decreased during the five day storage of platelets. A substantial population of platelets lacking the GPI-linked proteins were detected in most cases. We demonstrated varying degrees of deficiency in the expression of GPI-anchored molecules with neutrophils, monocytes and platelets with the highest proportion of deficient cells found within monocytic lineage. Similar numbers of platelets with the PNH phenotype and normal platelets expressed activation markers before and after exposure to platelet agonists. Flow cytometry is more sensitive than Ham's test in monitoring expression of PNH in platelets. Differences in the numbers of circulating GPI-deficient platelets and myeloid cells suggest that either the survival of platelets and mature myeloid cells differs or megakaryocytopoeisis is abnormal within the GPI-deficient clone.

Anemia, Aplastic↗

PubMed1996

Intercellular transfer of a glycosylphosphatidylinositol (GPI)-linked protein: release and uptake of CD4-GPI from recombinant adeno-associated virus-transduced HeLa cells.

A diverse group of GPI-anchored protein structures are ubiquitously expressed on the external cell membranes of eukaryotes. Whereas the physiological role for these structures is usually defined by their protein component, the precise biological significance of the glycolipid anchors remains vague. In the course of producing a HeLa cell line (JM88) that contained a recombinant adeno-associated virus genome expressing a GPI-anchored CD4-GPI fusion protein on the surface of the cells, we noted the transfer of CD4-GPI to native HeLa cells. Transfer occurred after direct cell contact or exposure to JM88 cell supernatants. The magnitude of contact-mediated CD4-GPI transfer correlated with temperature. Supernatant CD4-GPI also attached to human red blood cells and could be cleaved with phosphatidylinositol-specific phospholipase C. The attached CD4-GPI remained biologically active after transfer and permitted the formation of syncytium when coated HeLa cells were incubated with glycoprotein 160 expressing H9 cells. JM88 cells provide a model for the production, release, and reattachment of CD4-GPI and may furnish insight into a physiologic role of naturally occurring GPI-anchored proteins. This approach may also allow the production of other recombinant GPI-anchored proteins for laboratory and clinical investigation.

CD4 Antigens↗

PubMed1996

The BCR-ABL oncogene requires both kinase activity and src-homology 2 domain to induce cytokine secretion.

Expression of either the BCR-ABL or the v-abl oncogene in the factor-dependent murine myeloid cell line FDCP-1 results in growth factor independence. Studies with temperature-sensitive mutants of v-abl show that this growth factor independence is oncogene dependent. Likewise, cells expressing a kinase inactive mutant of BCR-ABL did not grow in the absence of interleukin-3 (IL-3). Conditioned media from cells expressing either v-abl or BCR-ABL contained growth factor(s) capable of stimulating the proliferation of uninfected FDCP-1 cells. Based on enzyme-linked immunosorbent assay studies and antibody neutralization studies, the major growth factor present in these conditioned media is IL-3. Because of the importance of SH2 domains in regulating substrate interactions, we examined the ability of SH2 deletion mutants in BCR-ABL to induce growth factor independence. Cells expressing a mutant of BCR-ABL lacking the SH2 domain were growth factor independent; however, they did not secrete growth factors. This finding suggests that while IL-3 produced by cells infected with BCR-ABL may contribute to autocrine or paracrine growth factor independence, expression of an activated tyrosine kinase alone may be able to induce growth factor independence. Furthermore, the secretion of cytokines maybe correlated with a specific region of the BCR-ABL oncogene, suggesting that activation (phosphorylation) of specific substrates may be critical for transcriptional activation of cytokine genes.

Animals↗

PubMed1996

p53 protein expression and gene analysis in clear cell adenocarcinoma of the vagina and cervix.

OBJECTIVE: p53 is the most commonly mutated gene in human cancers. The objective of this study was to determine if clear cell adenocarcinomas (CCAs) of the vagina and cervix are associated with p53 gene mutations or alterations in p53 tumor-suppressor protein expression. METHODS: Paraffin-embedded tissue specimens from 21 women (median age 22 years) with clear cell adenocarcinoma of the vagina or cervix were studied. Fifteen women had a prior history of in utero exposure to diethylstilbestrol. p53 protein expression was detected by immunohistochemical (IHC) analysis with monoclonal antibody DO-7 (Dako Corp.) which recognizes both wild-type and mutant p53 proteins. For p53 gene analysis, genomic DNA from malignant tissue was isolated and exons 4-10 were amplified by PCR and subjected to mutation screening by single-stranded conformation polymorphism (SSCP) analysis. RESULTS: p53 protein was detected by IHC in tumors from 14 of 21 cases (67%). The observed p53 staining patterns were heterogeneous in both the proportion and intensity of tumor cells stained but were clearly overexpressed relative to the surrounding benign stroma. Metastatic tumors from 3 women with metastatic disease were also positive for p53 staining. SSCP analysis did not identify p53 mutations in any of the cases and strongly suggests that the tumors contained only wild-type p53 alleles. CONCLUSIONS: Recent studies have demonstrated that wild-type p53 may accumulate in response to DNA damage which normally leads to growth arrest or programmed cell death. Our observations are consistent with the hypothesis that p53 overexpression in CCAs of the vagina and cervix is a response to generalized DNA damage, rather than a result of p53 protein half-life prolongation resulting from mutational inactivation of p53. Overexpression of wild-type p53 protein in vaginal and cervical CCA may relate to the more favorable prognosis of this subset of tumors in comparison to other gynecologic tumors containing mutated p53 genes.

Adenocarcinoma, Clear Cell↗

PubMed1996

Short-term fluctuations in the detection of cervical human papillomavirus DNA.

OBJECTIVE: To obtain point and cumulative prevalence estimates of cervical human papillomavirus (HPV) infection using two HPV DNA detection methods with different end point sensitivities; compare cervical swab and cervicovaginal lavage specimen collection methods for subsequent evaluation by polymerase chain reaction (PCR); and evaluate potential effects of the menstrual cycle on HPV DNA detection. METHODS: Seventy-two college women participated in a 10-week follow-up study. Cervical samples were obtained for HPV DNA detection and typing at each clinic visit, and information was collected concerning menstrual cycle and sexual and hygienic behaviors. Human papillomavirus DNA was detected by the ViraPap HPV DNA dot-blot assay and a broad-spectrum PCR HPV DNA amplification system. RESULTS: On a weekly basis, point prevalence for HPV infection by the ViraPap assay ranged from 4.2 to 9.7%, and the cumulative prevalence was 13.9%. Point prevalence by the broad-spectrum PCR assay ranged from 20.8 to 47.2%, and the cumulative HPV prevalence was 58.3%. Using cervicovaginal lavage specimens, we found lower cervical HPV prevalence estimates when compared with cervical swab specimens in the HPV PCR-based assay. No correlation between HPV DNA detection and phase of menstrual cycle was observed. CONCLUSION: Short-term HPV DNA detection is highly variable within individuals; therefore, single-point measurements of cervical HPV have limitations when assessing an individual's HPV status. The relationship between short-term and long-term HPV DNA persistence profiles may prove relevant to determining the risk of developing cervical intraepithelial neoplasia.

Adult↗

PubMed1996

Effects of chronic stress on food acquisition, plasma hormones, and the estrous cycle of female rats.

Our laboratory has previously conducted a number of studies to determine the effects of chronic stress on the physiology and behavior of male rats. The present study was performed to extend these investigations to female rats. Female rats were chronically stressed using a behavioral paradigm of around-the-clock signalled intermittent foot shock in which some rats can pull a chain to avoid/escape shock (stress) while another group of rats is yoked to the first group (yoked-stress) and does not have control over shock termination. Control rats were never shocked but all groups lever pressed for food pellets on an FR1 schedule (one pellet per lever press). Daily vaginal samples were obtained for several weeks prior to stress onset and throughout the chronic stress period. After 14 days of stress, the experiment was terminated and morning blood samples were collected for hormonal assays. Stress transiently decreased lever pressing for food pellets and body weights, but both measures returned to prestress levels by day 14 of stress. Plasma adrenocorticotropic hormone (ACTH) concentrations were significantly elevated in the yoked-stress group compared to the other two groups, but there were no significant effects of 14 days of stress treatment on plasma corticosterone, prolactin, estradiol, or progesterone concentrations. There were no significant differences in estrous cycle length among experimental groups.

Adrenocorticotropic Hormone↗

PubMed1996

Immunohistochemical evaluation of HER-2/neu expression in pancreatic adenocarcinoma and pancreatic intraepithelial neoplasms.

Although several morphological and molecular genetic studies have implicated various grades of pancreatic duct hyperplasia as precursor lesions to infiltrating pancreatic adenocarcinoma, the identity of preinvasive pancreatic neoplasms remains controversial. In the present study, the authors examined the expression of the epidermal growth factor receptor homologue, HER-2/neu (c-erbB-2), in pancreatic duct lesions adjacent to infiltrating pancreas cancers in a series of 19 cases of pancreatic duct adenocarcinoma. HER-2/neu expression was examined because it has been identified in a proportion of infiltrating pancreas cancers and because it may provide early neoplasms with a growth advantage over adjacent nonneoplastic epithelium. In normal pancreatic ducts and ductules, HER-2/neu expression was absent in all but one case. By contrast, HER-2/neu was expressed in 82% (P = .008 vs normal ) of ducts with flat mucinous hyperplasia, 86% (P = .03 vs normal) of ducts with papillary mucinous hyperplasia without atypia, 92% (P = .001 vs normal) of ducts with atypical papillary mucinous hyperplasia, and all specimens with carcinoma in situ. HER-2/neu expression was observed in 69% (P = .002 vs normal) of the moderately differentiated infiltrating carcinomas and none of the poorly differentiated infiltrating carcinomas. These data establish HER-2/neu as a potential mediator of growth factor-related signal transduction in pancreatic duct lesions, and provide additional support for the hypothesis that lesions formerly regarded as various grades of hyperplasia instead may represent intraepithelial neoplasms with the potential for subsequent invasion and metastasis.

Adenocarcinoma↗

PubMed1996

Functional motor outcome in children with myelomeningocele: correlation with anatomic level on prenatal ultrasound.

Fifteen children with prenatally diagnosed myelomeningocele were followed for at least three years to determine the relations between prenatal anatomic level visualized on high-resolution ultrasound, radiographic level, neuromotor level and functional motor outcome. Prenatal anatomic level accurately predicted neuromotor level and functional motor outcome in 12 of the children and was a better predictor than motor level at birth. Clinicians involved in prenatal counseling may use the anatomic level determined on high-resolution ultrasound to discuss motor prognosis with families.

Child, Preschool↗

PubMed1996

Effect of low-level basal plus marked "pulsatile" hyperglycemia on insulin secretion in fetal sheep.

We compared fetal glucose- and arginine-stimulated insulin secretion (delta I, pM) among four groups of pregnant sheep after 10-11 days of different maternal glycemic patterns: 1) control, euglycemic; 2) low-level basal plus "pulsatile" hyperglycemic (PHG group); 3) markedly hyperglycemic (HG) group); 4) markedly hypoglycemic (LG group). Mean delta I during a hyperglycemic clamp was greatest in the PHG group (190 +/- 28 pM, P < 0.01) and least in the HG (64 +/- 13 pM, P < 0.05) and LG groups (68 +/- 15 pM, P < 0.05) compared with the control group (126 +/- 18 pM). After an arginine bolus, insulin concentration was greater in the PHG group at two of four sampling times over 30 min compared with the control group and at all times compared with the HG and LG groups. The trend in mean delta I over the postarginine sampling period (PHG 1,092 +/- 114 pM; control 921 +/- 86 pM; HG897 +/- 117 pM; LG831 +/- 57 pM) was in the same direction as for glucose and was significant (P < 0.05). Thus glucose-stimulated fetal insulin secretion is regulated by the duration and pattern, as well as the magnitude, of maternal and fetal hyperglycemia; this regulation may also extend to insulin-secretion capacity.

Animals↗

PubMed1996

Induction of growth factor-independence and GM-CSF secretion by the v-src oncogene in murine myeloid cells does not require membrane association of pp60v-src.

Introduction of v-src or c-src527F, a transforming mutant of the c-src proto-oncogene, into the growth factor-dependent cell line FDCP-1 resulted in growth factor independence. Temperature-shift studies with cells carrying the tsLA29 mutant of v-src demonstrated that growth factor independence was oncogene-dependent; that is, the cells were growth factor-independent at the permissive temperature but became growth factor-dependent at the nonpermissive temperature. Introduction of the c-src proto-oncogene did not result in growth factor independence. The c-src2A,527F mutant, which encodes an activated tyrosine kinase but does not transform fibroblasts due to a mutation in the membrane localization sequence, induced growth factor independence. This suggests that the presence of an activated tyrosine kinase is necessary for this process but that membrane localization is not. Bioassays indicated that conditioned medium from growth factor-independent cells contained a growth factor identified by antibody neutralization studies as granulocyte-macrophage colony-stimulating factor (GM-CSF). Secretion of GM-CSF was confirmed by a quantitative enzyme-linked immunosorbent assay (ELISA) specific for GM-CSF. The presence of GM-CSF mRNA in src-infected FDCP-1 cells was demonstrated by PCR amplification of cDNAs with primers specific for GM-CSF. While GM-CSF mRNA was detected in FDCP/ts29 cells grown at 34 degrees C, it was not observed in cells infected with the tsLA29 mutant grown at the nonpermissive temperature of 39 degrees C. Transfection of v-src-infected FDCP-1 cells with a GM-CSF promoter reporter plasmid revealed src-dependent expression of luciferase; that is, while expression was observed at the permissive temperature, no expression was detected in FDCP/ts29 clone 6 cells grown at the nonpermissive temperature. No expression of the GM-CSF promoter reporter plasmid was observed in uninfected FDCP-1 cells.

Animals↗

PubMed1996

Ovulation induction for infertility is it safe or not?

Case reports of ovarian tumors in women undergoing fertility treatment have raised questions about the potential neoplastic effects of ovulation-induction agents used in the treatment of infertility. This has been the subject of much debate, media coverage and patient alarm. An increased risk of malignant epithelial ovarian cancer, borderline epithelial ovarian tumors, and nonepithelial ovarian cancer have been reported in association with the use of fertility drugs. Further review of the literature reveals that there are limitations to the studies reporting this association and indicates that further research is needed before a causal relationship can be established.

Adult↗