Pentasomy of chromosome 8 in chronic myelomonocytic leukemia.
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Aneuploidy↗
Biomedical subjects
N Dean
Publications and source records attributed to N Dean.
Pretreatment with an oral contraceptive is effective in reducing the incidence of functional ovarian cyst formation during pituitary suppression by gonadotropin-releasing hormone analogues.
PURPOSE: Our purpose was to assess the effect of pretreatment with oral contraceptives (OCs) on the formation of functional ovarian cysts during pituitary suppression with gonadotropin-releasing hormone (GnRH) agonists, subsequent follicular development, and pregnancy rates. METHODS: A retrospective case-controlled study of 31 in vitro fertilization (IVF) patients, all of whom in a previous cycle had commenced the long protocol of GnRH-agonist (Buserelin) in the early follicular phase and were pretreated in a subsequent cycle with 2 weeks of an OC containing 30 micrograms of ethinyl estradiol and 150 micrograms of desogestrel prior to GnRH-agonist administration, was undertaken. Follow-up visits were arranged after a minimum of 11 days of GnRH-agonist administration and weekly thereafter until pituitary suppression was achieved. RESULTS: Cysts were detected in 16 (51.6%) of the 31 patients not pretreated with OCs, and in 0 (0%) of the 31 patients pretreated with OCs (odds ratio = 67.1; 95% confidence interval = 5.6-350.7). Patients pretreated with OCs achieved pituitary suppression more rapidly (median difference = 4 days; 95% confidence interval = 2-7) and had comparable gonadotropin requirements and pregnancy rates. CONCLUSIONS: Pretreatment with OCs prior to pituitary suppression in the early follicular phase decreases ovarian cyst formation, without an apparent effect on subsequent follicular recruitment or pregnancy rates.
Adult↗
An ectopic pregnancy masked by follicular initiation of gonadotropin-releasing hormone agonist for pituitary desensitization prior to in vitro fertilization.
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Adult↗
The JUN kinase/stress-activated protein kinase pathway is required for epidermal growth factor stimulation of growth of human A549 lung carcinoma cells.
Epidermal growth factor (EGF) plays a major role in non-small cell lung cancer cell autocrine growth and has been reported to activate the JUN kinase/stress-activated protein kinase (JNK/SAPK) pathway in model cells. Activation of JNK/SAPK leads to the phosphorylation of c-JUN protooncogene on serines 63 and 73. This mechanism is required for and cooperates in the transformation of rat embryo fibroblasts by Ha-RAS. However, the function of JNK/SAPK in human tumor growth is unknown. We have tested several lung carcinoma cell lines. All exhibited UV-C-inducible JNK/SAPK activity; two exhibited constitutive activity in low serum, and two (M103 and A549) exhibited EGF-inducible JNK/SAPK activity. In A549 cells, EGF induced a rapid and prolonged (up to 24 h) activation of the JNK/SAPK pathway that correlated with a 150-190% growth stimulation. Stably transfected clones of A549 cells expressing c-JUN(S63A,S73A), a transdominant inhibitor of c-JUN, completely blocked the EGF-stimulated proliferation effect but did not alter the basal proliferation rate. Consistent with these results JNK antisense oligonucleotides targeted to JNK1 and JNK2 entirely eliminated the EGF-stimulated JNK/SAPK activity and blocked EGF-stimulated growth but not basal growth. In contrast, specific inhibition of the RAF/ERK pathway by PD98059 (MEK1 inhibitor) completely blocked ERK activation by EGF and basal cell growth but not EGF-stimulated growth, thereby dissociating the growth-promoting roles of each pathway. Our observations indicate, for the first time, that JNK/SAPK may be a preferential effector pathway for the growth properties of EGF in A549 cells.
Animals↗
The VRG4 gene is required for GDP-mannose transport into the lumen of the Golgi in the yeast, Saccharomyces cerevisiae.
In the yeast Saccharomyces cerevisiae, glycoproteins and sphingolipids are modified in the Golgi by the addition of mannose residues. The critical mannosyl donor for these reactions is the nucleotide sugar, GDP-mannose, whose transport into the Golgi from the cytoplasm is required for mannosylation. This transport reaction has been well characterized, but the nucleotide sugar transporter has yet to be identified in yeast. VRG4 is an essential gene whose product is required for a number of Golgi-specific functions, including glycosylation and the organization of the endomembrane system. Here, data are presented that demonstrate that the primary role of Vrg4p is in the transport of GDP-mannose into the Golgi. The vrg4 mutation causes a general impairment in mannosylation, affecting N-linked and O-linked glycoprotein modifications as well as the mannosylation of sphingolipids. By using an in vitro assay, vrg4 mutants were shown to be specifically defective in the transport of GDP-mannose into Golgi vesicles. The Vrg4 protein localizes to the Golgi complex in a pattern that suggests a wide distribution throughout the Golgi. Vrg4p displays homology to other putative nucleotide sugar transporters, suggesting that the VRG4 gene encodes a Golgi GDP-mannose transporter. As Vrg4p is essential, these results suggest that a complete lack of mannosylation of glycoproteins in the Golgi leads to inviability. Alternatively, the essential function of Vrg4p in yeast involves its effect on sphingolipids, which would imply a critical role for mannosylinositol phosphorylceramides or mannosyl diphosphoinositol ceramides on growth and viability.
Biological Transport↗
Protein kinase C-zeta mediates angiotensin II activation of ERK1/2 in vascular smooth muscle cells.
Activation of 44 and 42 kDa extracellular signal-regulated kinases (ERK)1/2 by angiotensin II (angII) plays an important role in vascular smooth muscle cell (VSMC) function. The dual specificity mitogen-actived protein (MAP) kinase/ERK kinase (MEK) activates ERK1/2 in response to angII, but the MEK activating kinases remain undefined. Raf is a candidate MEK kinase. However, a kinase other than Raf appears responsible for angII-mediated signal transduction because we showed previously that treatment with 1 microM phorbol 12, 13-dibutyrate (PDBU) for 24 h completely blocked Raf-Ras association in VSMC but did not inhibit activation of MEK and ERK1/2 by angII. We hypothesized that an atypical protein kinase C (PKC) isoform, which lacks a phorbol ester binding domain, mediated ERK1/2 activation by angII. Western blot analysis of rat aortic VSMC with PKC isoform-specific antibodies showed PKC-alpha, -beta1, -delta, -epsilon, and -zeta in relative abundance. All isoforms except PKC-zeta were down-regulated by 1 microM PDBU for 24 h suggesting that PKC-zeta was responsible for angII-mediated ERK1/2 activation. In response to angII, PKC-zeta associated with Ras as shown by co-precipitation of PKC-zeta with anti-H-Ras antibody. To characterize further the role of PKC-zeta, PKC-zeta protein was depleted specifically by transfection with antisense PKC-zeta oligonucleotides. Antisense PKC-zeta oligonucleotide treatment significantly decreased PKC-zeta protein expression (without effect on other PKC isoforms) and angII-mediated ERK1/2 activation in a concentration-dependent manner. In contrast, ERK1/2 activation by platelet-derived growth factor and phorbol ester was not significantly inhibited. These results demonstrate an important difference in signal transduction by angII compared with PDGF and phorbol ester in VSMC, and suggest a critical role for PKC-zeta and Ras in angII stimulation of ERK1/2.
Angiotensin II↗
Prospective randomized trial of the effect of two flushing media on oocyte collection and fertilization rates after in vitro fertilization.
OBJECTIVE: To assess the value of heparinized saline as a flushing medium for oocyte recovery. DESIGN: Prospective randomized study. SETTING: Academic tertiary referral center for fertility treatment. PATIENT(S): Thirty-five patients, with both ovaries intact having IVF-ET. INTERVENTION(S): Patients were randomized either to have the follicles of the left or right ovary flushed with heparinized normal saline at the time of oocyte recovery for IVF-ET. The contralateral ovary was flushed with heparinized culture medium. Oocytes obtained from each side were cultured separately and assessed for fertilization 18-21 hours after insemination. MAIN OUTCOME MEASURE(S): Collection and fertilization rates. RESULT(S): A total of 481 follicles were aspirated yielding 366 oocytes. Of these, 240 fertilized. From the side flushed with saline 185 oocytes were collected from 237 follicles, which was not significantly different from 181 oocytes collected from 244 follicles on the side flushed with culture medium (odds ratio = 1.23; 95% confidence interval = 0.79-1.92). Similarly, there was no significant difference observed in fertilization rates between oocytes obtained after saline (median 71.4%) and culture medium flush (median 75.0%) (odds ratio = 1.08; 95% confidence interval = 0.68-1.72). CONCLUSION(S): Heparinized normal saline is an equally good but cheaper and more convenient medium than standard heparinized culture medium and could replace it for flushing follicles during oocyte recovery for IVF-ET procedures.
Adult↗
Saccharomyces cerevisiae HOC1, a suppressor of pkc1, encodes a putative glycosyltransferase.
The Saccharomyces cerevisiae gene PKC1 encodes a protein kinase C isozyme that regulates cell wall synthesis. Here we describe the characterization of HOC1, a gene identified by its ability to suppress the cell lysis phenotype of pkc1-371 cells. The HOC1 gene (Homologous to OCH1) is predicted to encode a type II integral membrane protein that strongly resembles Och 1p, an alpha-1,6-mannosyltransferase. Immunofluorescence studies localized Hoc1p to the Golgi apparatus. While overexpression of HOC1 rescued the pkc1-371 temperature-sensitive cell lysis phenotype, disruption of HOC1 lowered the restrictive temperature of the pkc1-371 allele. Disruption of HOC1 also resulted in hypersensitivity to Calcofluor White and hygromycin B, phenotypes characteristic of defects in cell wall integrity and protein glycosylation, respectively. The function of HOC1 appears to be distinct from that of OCH1. Taken together, these results suggest that HOC1 encodes a Golgi-localized putative mannosyltransferase required for the proper construction of the cell wall.
Amino Acid Sequence↗
Inhibition of growth of human tumor cell lines in nude mice by an antisense of oligonucleotide inhibitor of protein kinase C-alpha expression.
A 20-mer phosphorothioate oligodeoxynucleotide (ISIS 3521) designed to hybridize sequences in the 3'-untranslated region of human protein kinase C-alpha (PKC-alpha) mRNA has been shown to inhibit the expression of PKC-alpha in multiple human cell lines. In human bladder carcinoma (T-24) cells, inhibition of PKC-alpha was both concentration dependent and oligonucleotide sequence specific. ISIS 3521 had a IC50 of 50-100 nM for PKC-alpha mRNA reduction and was without effect on the expression of other members of the PKC family of genes (PKC-eta and zeta). Toxicity studies in mice revealed that the oligodeoxynucleotide was well tolerated at repeat doses of 100 mg/kg i.v. for up to 14 days, with no acute toxicity apparent. The oligodeoxynucleotide was found to also inhibit the growth of three different human tumor cell lines, the T-24 bladder, human lung carcinoma (A549), and Colo 205 colon carcinoma grown in nude mice. The inhibition was dose dependent with ID50 values for the growth inhibition between 0.06 and 0.6 mg/kg daily when given i.v., depending on the cell line examined. Three control phosphorothioate oligodeoxynucleotides not targeting human PKC-alpha were without effect on the growth of the tumors at doses as high as 6 mg/kg. Recovery of ISIS 3521 from tumor tissue and resolution by capillary gel electrophoresis revealed that 24 It after the final dose of oligodeoxynucleotide, intact, full-length 20-mer material was present as well as some apparent exonuclease degradation products (e.g., n-1 and n-2 mers). These studies demonstrate the in vivo antitumor effects of an antisense oligodeoxynucleotide targeting PKC-alpha and suggest that this compound may be of value as a chemotherapeutic agent in the treatment of human cancers.
Animals↗
The yeast VRG4 gene is required for normal Golgi functions and defines a new family of related genes.
Sodium vanadate is an effective agent for the enrichment of yeast mutants with defects in glycosylation steps that occur in the Golgi complex (Ballou, L., Hitzeman, R. A., Lewis, M. S., and Ballou, C. E. (1991) Proc. Natl. Acad. Sci. U. S. A. 88, 3209-3212). We isolated and screened vanadate-resistant glycosylation mutants in the budding yeast, Saccharomyces cerevisiae, to identify any that may be defective in the secretory pathway, since changes in normal glycosylation may reflect defects within the secretory pathway. We identified one such mutant, allelic to vrg4/van2, that is defective in processes that occur specifically in the Golgi complex. Protein secreted from vrg4 mutants lacks the outer chain glycosylation that is normally extended during passage through the Golgi. This mutant fails to retrieve soluble endoplasmic reticulum proteins from the Golgi and accumulates the Golgi-specific biosynthetic intermediate of the vacuolar protein, carboxypeptidase Y. Analyses of intracellular membranes by staining with the fluorescent lipophilic dye, DiOC6, and by electron microscopy reveals a dramatic alteration in the membrane morphology of vrg4 mutant cells. The VRG4 gene encodes a 36.9-kDa membrane protein that is essential for cell viability. A sequence homology search has identified five related genes, establishing that VRG4 is a founding member of a family of structurally similar genes. Taken together, these results suggest that the VRG4 gene plays an important role in regulating Golgi functions and in maintaining the normal organization of intracellular membranes.
Amino Acid Sequence↗
The OST4 gene of Saccharomyces cerevisiae encodes an unusually small protein required for normal levels of oligosaccharyltransferase activity.
Sodium vanadate is an effective drug for the enrichment of yeast mutants defective in glycosylation reactions that are carried out in the Golgi complex. We have isolated vanadate-resistant, hygromycin B-sensitive mutants that act at very early steps of N-linked glycosylation, occurring in the endoplasmic reticulum. Here we describe the phenotypic characterization of ost4, a vanadate-resistant mutant that is defective in oligosaccharyltransferase (OTase) activity both in vivo and in vitro. The OST4 open reading frame is unusual in that it predicts a protein of only 36 amino acids. We demonstrate that the OST4 gene product is, in fact, an unusually small protein of approximately 3.6 kDa, predicted to lie almost entirely in the hydrophobic environment of the membrane. Strains carrying a disruption of the OST4 gene are viable but grow poorly at 25 degrees C. The null mutant is inviable at 37 degrees C, demonstrating that the OST4 gene product is essential for growth at high temperatures. Deletion of the OST4 gene greatly diminishes OTase activity but does not abolish it. These results suggest that the OST4 gene encodes a subunit or accessory component of OTase that is essential at high temperature.
Algorithms↗
Elective cryopreservation of all embryos in women at risk of developing ovarian hyperstimulation syndrome may not prevent the condition but reduces the live birth rate.
OBJECTIVE: Our goal was to evaluate the use of elective cryopreservation of all embryos to prevent the development of ovarian hyperstimulation syndrome in patients at risk while undergoing in vitro fertilization treatment. DESIGN: We analyzed 117 treatment cycles in which the serum E2 concentration on the day of hCG administration was > 10,000 pM and in whom > or = 15 oocytes were retrieved at ultrasound-directed follicle aspiration. The incidence of ovarian hyperstimulation syndrome, pregnancy, and live birth in 65 patients who had elective cryopreservation of all embryos and 52 patients who had fresh embryo transfer were compared. Independent t test and chi-square test (with Yates' correction) was used as appropriate. RESULTS: The clinical pregnancy (35 vs 17%; P < 0.03) and the live birth (27 vs 12%; P < 0.05) rates in patients receiving fresh embryo transfer was significantly higher than in those who had elective cryopreservation of all embryos. The incidence of moderate and severe ovarian hyperstimulation syndrome was similar in both groups (3.8 and 6.2%). CONCLUSIONS: Elective cryopreservation of all embryos does not reliably protect against the development of ovarian hyperstimulation syndrome but may reduce the clinical pregnancy and live birth rate.
Adult↗
Outcome of frozen embryo replacement cycles following elective cryopreservation of all embryos in women at risk of developing ovarian hyperstimulation syndrome.
AIM: Our aim was to compare the outcome in subsequent frozen embryo replacement cycles in four groups of patients who had elective cryopreservation of all their embryos because they were considered to be at increased risk of developing severe ovarian hyperstimulation syndrome. DESIGN: Sixty-two (91%) of 68 IVF cycles (68 patients) in which elective cryopreservation of all embryos was performed were analyzed. All patients continued on the GnRH agonist, buserelin, after oocyte recovery until the onset of vaginal bleeding. Frozen embryo replacement occurred in a hormone replacement cycle that started either on day 3 of the withdrawal bleed (group I; N = 15) or after serum estradiol levels had fallen to < 100 pmol/L (group II; N = 16). The other patients commenced a frozen embryo replacement cycle several months later in either a hormone replacement (group III; N = 15) or a natural (group IV; N = 16) cycle. RESULTS: Two patients developed severe ovarian hyperstimulation syndrome. There were no significant differences among the four groups regarding demographic variables, the dose of hMG used, and the clinical outcome. There was a higher but not significantly different clinical pregnancy rate in group I (26.7%), compared to group II (12.5%), group III (13.3%), and group IV (18.8%). CONCLUSIONS: Several options exist for the timing and protocol used for frozen embryo replacement in patients who had elective cryopreservation for the prevention of ovarian hyperstimulation syndrome, none of which was found to be clearly superior in this observational report.
Adult↗
Success of intrauterine insemination using cryopreserved donor sperm is related to the age of the woman and the number of preovulatory follicles.
OBJECTIVE: Our objective was to assess parameters associated with a successful outcome of intrauterine insemination (IUI) using cryopreserved donor sperm. DESIGN: We analyzed 750 consecutive donor IUI cycles undertaken by 363 women in an assisted conception clinic. The main outcome measure was clinical pregnancy. RESULTS: IUI was performed in 94.7% of the 750 IUI treatment cycles commenced and 180 clinical pregnancies occurred. The clinical pregnancy rate per cycle was 26.4%. The rate was significantly related to the patient's age (30.5% for age < or = 35 years and 18.1% for age > 35 years; P < 0.006) and whether there was one or more than one preovulatory follicles [20.9, 34.4, and 31.5% for one, two, and three or four follicles with a mean diameter of 14 or more mm at the time of human chorionic gonadotropin (hCG) administration; P = 0.006]. Two to four preovulatory follicles were present in 12.6% of the natural cycles, 43.6% of clomiphene citrate or tamoxifen, and 59.9% of gonadotropin stimulated cycles. The difference in the number of preovulatory follicles between stimulated and unstimulated cycles was highly significant (P < 0.0001). Pregnancy rates were 29.9% in gonadotropin-stimulated cycles, 23.6% in clomiphene citrate- or tamoxifen-stimulated cycles, 23.6% in clomiphene and 20.1% in unstimulated cycles. The difference in pregnancy rates between gonadotropin-stimulated and natural cycles was significant (P = 0.038). Cycle fecundity rates were not significantly affected by the number of previous treatment cycles, duration of infertility, gravidity and parity of the patient, presence of a spontaneous luteinizing hormone (LH) surge before the administration of hCG, or number of motile sperm in the insemination specimen. CONCLUSIONS: Success of IUI using cryopreserved donor sperm is related to the age of the women and whether there is one or more than one preovulatory follicles.
Cryopreservation↗
Comparison of intravenous albumin and transfer of fresh embryos with cryopreservation of all embryos for subsequent transfer in prevention of ovarian hyperstimulation syndrome.
OBJECTIVE: To compare the efficacy of administration i.v. albumin to prevent severe ovarian hyperstimulation syndrome (OHSS) in patients undergoing ovarian stimulation for IVF with a standard policy of cryopreserving all embryos and to assess the impact of the two methods of treatment on pregnancy rates (PRs). DESIGN: Prospective randomized study. SETTING: A tertiary referral center for assisted conception. PATIENTS: Twenty-six patients undergoing IVF treatment cycles who were considered to be at high risk of developing severe OHSS on the basis of their serum E2 concentrations on the day of hCG administration and the number of oocytes collected. INTERVENTION: In group 1 (n = 13) all the generated embryos were cryopreserved to be transferred subsequently in hormonally manipulated cycles. In group 2 (n = 13) patients received IV infusions of albumin on the day of oocyte retrieval and 5 days later. Patients in group 2 had transfers of fresh embryos. MAIN OUTCOME MEASURES: The total dosage of hMG used, total number of follicles developed, number of follicles > 14 mm in diameter, serum E2 concentrations and endometrial thickness on day of hCG administration, number of oocytes retrieved, number and quality of embryos generated, PRs per cycle commenced, and onset and degree of any OHSS developed. RESULTS: There were no significant differences in the above parameters between the two groups, except for PRs that were significantly higher in patients who had all embryos cryopreserved (38.6% versus 0%). CONCLUSION: The policy of cryopreserving all generated embryos appears as effective as the administration of i.v. albumin in preventing OHSS in high-risk patients and produces significantly higher PRs.
Adult↗
Molecular and phenotypic analysis of the S. cerevisiae MNN10 gene identifies a family of related glycosyltransferases.
The Saccharomyces cerevisiae mnn10 mutant is defective in the synthesis of N-linked oligosaccharides (Ballou et al., 1989). This mutation has no effect on O-linked sugars, but results in the accumulation of glycoproteins that contain severely truncated N-linked outer-chain oligosaccharides. We have cloned the MNN10 gene by complementation of the hygromycin B sensitivity conferred by the mutant phenotype. Sequence analysis predicts that Mnn10p is a 46.7 kDa type II membrane protein with structural features characteristic of a glycosyltransferase. Subcellular fractionation data indicate that most of the Mnn10 protein cofractionates with Golgi markers and away from markers for the endoplasmic reticulum (ER), suggesting Mnn10p is localized to the Golgi complex. A comparison of the Mnn10 protein sequence to proteins in the two different databases identified five proteins that are homologous to Mnn10p, including a well characterized Schizosaccharomyces pombe alpha 1,2 galactosyltransferase that resides in the Golgi complex. Taken together, these results suggest that MNN10 encodes a novel Golgi-localized mannosyltransferase contained in this previously unrecognized family of related sugar transferases.
Amino Acid Sequence↗
Yeast glycosylation mutants are sensitive to aminoglycosides.
Aminoglycosides are a therapeutically important class of antibiotics that inhibit bacterial protein synthesis and a number of viral and eukaryotic functions by blocking RNA-protein interactions. Vanadate-resistant Saccharomyces cerevisiae mutants with defects in Golgi-specific glycosylation processes exhibit growth sensitivity to hygromycin B, an aminoglycoside [Ballou, L., Hitzeman, R. A., Lewis, M. S. & Ballou, C. E. (1991) Proc. Natl. Acad. Sci. USA 88, 3209-3212]. Here, evidence is presented that glycosylation is, in and of itself, a key factor mediating aminoglycoside sensitivity in yeast. Examination of mutants with a wide range of glycosylation abnormalities reveals that all are sensitive to aminoglycosides. This effect is specific to aminoglycosides and not merely a consequence of increased permeability of the yeast mutants to drugs. Furthermore, inhibition of glycosylation in wild-type cells leads to a marked increase in their sensitivity to aminoglycosides. These results establish that a defect in glycosylation is sufficient to render yeast cells susceptible to these clinically important drugs. Further, they suggest that a molecule which prevents the uptake or mediates removal of aminoglycosides requires glycosylation for its activity. Perhaps more importantly, this finding on drug sensitivity provides the most powerful screen to date to identify mutants and thereby to isolate genes involved in all aspects of N-linked glycosylation.
Camptothecin↗
Cloning and DNA sequence of a Kluyveromyces lactis ERD1 homologue.
The ERD1 gene product is required for the correct localization of soluble proteins that normally reside in the endoplasmic reticulum (ER). Cell lacking ERD1 secrete resident ER proteins and, in addition, exhibit defects in the processing of glycoproteins. Here, the molecular characterization of the Kluyveromyces lactis ERD1 homologue is described. A comparison of the predicted sequences of the Saccharomyces cerevisiae and K. lactis Erd1 proteins indicates that they are about 30% identical and 50% similar in sequence. Despite low sequence identity, these proteins are predicted to be conserved structurally. Furthermore, the K. lactis protein can functionally complement an S. cerevisiae mutant containing a deletion of the entire ERD1 gene, indicating these two proteins are functional homologues.
Amino Acid Sequence↗