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1.  Deceased donor organ transplantation: A single center experience from Cape Town, South Africa 
Indian Journal of Nephrology  2012;22(2):86-87.
Deceased donor kidney transplantation have been in place for more than ten years at Groote Schuur Hospital in Cape Town, South Africa. This retrospective review between 1995 and 2005 reports the experience with 824 deceased donor referrals. Race breakdown showed that 321 donors were black, 154 white, 318 mixed race and 30 unrecorded. Consent remains a major problem in South Africa and we were unable to obtain consent in 43% of our patients. Only 20% of donors had natural causes of death – the majority died because of trauma/unnatural circumstances. For this reason the average age of our donors are 26 years. A and O blood group donors were the most prevalent with A blood group patients making up 38% and O blood group 39% of the donor population.
doi:10.4103/0971-4065.97108
PMCID: PMC3391828  PMID: 22787307
Deceased donor transplantation; kidney transplantation; transplantation in developing countries
2.  In vitro evaluation of the performance of Granada selective enrichment broth for the detection of group B streptococcal colonization 
A broth for the screening of group B streptococcal (GBS) carriage during pregnancy is about to be introduced. Simulating conditions in everyday practice, we have compared the sensitivity of this Granada tube broth (GT) with that of classical Amies transport medium (AT) in vitro. A total of 1,485 GT and 1,485 AT were tested with 33 well-characterized GBS strains in three different concentrations, five different incubation times, and three different temperatures. After initial incubation at room temperature (RT) or 4°C, GT were placed at 37°C. GT were scored for the presence of orange pigment. GT and AT were subcultured on blood agar (BA). Pigment was observed in 98% of GT incubated at 37°C. GBS could be cultured in 91%, 73%, and 55% of GT incubated at 37°C, RT, or 4°C, respectively. For AT, these percentages were only 20% at 37°C, 52% at RT, and 59% at 4°C. When GT initially incubated at RT or 4°C were subsequently incubated at 37°C, the sensitivity improved significantly. We conclude that GT is a more sensitive GBS transport and culture medium than the conventional method, especially for low inocula and prolonged transport/incubation times. GT does not exclude the presence of GBS, and should always be incubated at 37°C and subcultured on solid agar for optimal sensitivity.
doi:10.1007/s10096-011-1317-8
PMCID: PMC3274678  PMID: 21698495
3.  Detection of Mycoplasma hyopneumoniae by polymerase chain reaction in swine presenting respiratory problems 
Brazilian Journal of Microbiology  2008;39(3):471-476.
Since Mycoplasma hyopneumoniae isolation in appropriate media is a difficult task and impractical for daily routine diagnostics, Nested-PCR (N-PCR) techniques are currently used to improve the direct diagnostic sensitivity of Swine Enzootic Pneumonia. In a first experiment, this paper describes a N-PCR technique optimization based on three variables: different sampling sites, sample transport media, and DNA extraction methods, using eight pigs. Based on the optimization results, a second experiment was conducted for testing validity using 40 animals. In conclusion, the obtained results of the N-PCR optimization and validation allow us to recommend this test as a routine monitoring diagnostic method for Mycoplasma hyopneumoniae infection in swine herds.
doi:10.1590/S1517-838220080003000011
PMCID: PMC3768421  PMID: 24031248
Swine Enzootic Pneumonia; Mycoplasma hyopneumoniae; diagnosis; Nested- PCR
4.  Oncology patients' experience at the interface between hospital and community care: a mixed method investigation 
Introduction
Oncology patients often experience breakdowns in care when transitioning between care settings.
Aims and objectives
To examine the experience of oncology patients at the transition between hospital and community care and identify factors which affect fragmentation.
Methods
We used a complementary mixed method approach. Qualitative phase: semi-structured interviews and focus groups were conducted with patients and their caregivers, nurses, social workers, physicians and medical administrators. Quantitative phase: a survey was administered to 400 oncology patients of a large tertiary medical center in Northern Israel. Patients who were discharged from the hospital completed a validated questionnaire on their transition from the hospital to the community and on their perceptions of the quality of their primary care. The surveys were administered in Hebrew, Arabic, and Russian.
Results
From the preliminary analysis of the qualitative data four broad themes emerged: (1) responsibility for care, (2) administrative and bureaucratic burden, (3) informal routes of communication, and (4) cultural barriers. The regression analyses examined the effect of patient characteristics (gender, age, education, income, health status, and language group) and showed that patients' language accounted for most of the variance in quality scores. Russian speaking patients reported poorer quality of care and Arabic speaking patients reported better quality of care, than Hebrew speakers, in all primary care domains. Both Arabic and Russian speakers scored significantly higher on the Care Transition Measure than Hebrew speakers.
Conclusions
The differences between sub-groups found here suggest that avoidable variations in care exist. To enable a more streamlined process, cultural issues need to be addressed at the interface between care settings. Further research should examine the causes for such differences.
PMCID: PMC2430304
oncological care; quality of care; transition; hospital care; primary care; Israel
5.  Gastrin releasing peptide receptor expression is decreased in patients with Crohn’s disease but not in ulcerative colitis 
Journal of Clinical Pathology  2004;57(10):1047-1051.
Background: Gastrin releasing peptide (GRP) and neuromedin B are bombesin (BN)-like peptides involved in regulating motility and inflammation in the gastrointestinal tract, which may be useful in treating inflammatory bowel disease (IBD). Three bombesin-like peptide receptors have been reported, but no studies have investigated their localisation in normal and inflamed human intestine.
Aim: To localise and characterise BN receptors in normal intestine and to see whether this is modified in IBD.
Methods: Full thickness intestinal tissue samples were collected from 13 patients with Crohn’s disease (CD), 11 with ulcerative colitis (UC), and 19 controls. BN receptor expression was characterised and quantified with storage phosphor autoradiography using BN, GRP, neuromedin B, and the synthetic analogue BN(6–14) as ligands.
Results: Only BN receptor type 2 (high affinity for GRP) was present in intestinal tissue. Minimal BN binding was detected in the mucosa. In normal colonic smooth muscle, mean BN binding was 336 fmol/g tissue in longitudinal muscle, including the myenteric plexus, and 71 fmol/g in circular muscle. In CD, colonic smooth muscle BN binding was significantly decreased (longitudinal muscle, 106; circular muscle, 19 fmol/g), in contrast to UC (377 and 62 fmol/g, respectively). In CD, a small (not significant) decrease was seen in ileal muscle compared with controls (111 v 169 and 18 v 32 fmol/g tissue for longitudinal and circular muscle, respectively).
Conclusions: Only the GRP receptor is expressed in human intestine; expression is highest in longitudinal muscle and myenteric plexus of the colon. Expression is decreased in inflamed and non-inflamed colon of CD, but not in UC.
doi:10.1136/jcp.2003.014993
PMCID: PMC1770439  PMID: 15452158
bombesin receptor; inflammatory bowel disease; autoradiography
6.  HGF/SF and its receptor c-MET play a minor role in the dissemination of human B-lymphoma cells in SCID mice 
British Journal of Cancer  1999;81(1):43-53.
The MET protooncogene, c-MET, encodes a cell surface tyrosine kinase receptor. The ligand for c-MET is hepatocyte growth factor (HGF), also known as scatter factor (SF), which is known to affect proliferation and motility of primarily epithelial cells. Recently, HGF/SF was also shown to affect haemopoiesis. Studies with epithelial and transfected NIH3T3 cells indicated that the HGF/SF–c-MET interaction promotes invasion in vitro and in vivo. We previously demonstrated that HGF/SF induces adhesion of c-MET-positive B-lymphoma cells to extracellular matrix molecules, and promoted migration and invasion in in vitro assays. Here, the effect of HGF/SF on tumorigenicity of c-MET-positive and c-MET-negative human B-lymphoma cell lines was studied in C.B-17 scid/scid (severe combined immune deficient) mice. Intravenously (i.v.) injected c-MET-positive (BJAB) as well as c-MET-negative (Daudi and Ramos cells) B-lymphoma cells formed tumours in SCID mice. The B-lymphoma cells invaded different organs, such as liver, kidney, lymph nodes, lung, gonads and the central nervous system. We assessed the effect of human HGF/SF on the dissemination of the B-lymphoma cells and found that administration of 5 μg HGF/SF to mice, injected (i.v.) with c-MET-positive lymphoma cells, significantly (P = 0.018) increased the number of metastases in lung, liver and lymph nodes. In addition, HGF/SF did not significantly influence dissemination of c-MET-negative lymphoma cells (P = 0.350 with Daudi cells and P = 0.353 with Ramos cells). Thus the effect of administration of HGF/SF on invasion of lymphoma cells is not an indirect one, e.g. via an effect on endothelial cells. Finally, we investigated the effect of HGF/SF on dissemination of c-MET-transduced Ramos cells. In response to HGF/SF, c-MET-transduced Ramos cells showed an increased migration through Matrigel in Boyden chambers compared to wild-type and control-transduced Ramos cells. The dissemination pattern of c-MET-transduced cells did not differ from control cells in in vivo experiments using SCID mice. Also no effect of HGF/SF administration could be documented, in contrast to the in vitro experiments. From our experiments can be concluded that the HGF/SF–c-MET interaction only plays a minor role in the dissemination of human B-lymphoma cells. © 1999 Cancer Research Campaign
doi:10.1038/sj.bjc.6690649
PMCID: PMC2374344  PMID: 10487611
HGF/SF; c-MET; retroviral transduction; human B-lymphoma cells; dissemination; SCID mice
7.  Chemoimmunotherapy with bleomycin, vincristine, lomustine, dacarbazine (BOLD) plus interferon alpha for metastatic melanoma: a multicentre phase II study. 
British Journal of Cancer  1997;76(2):266-269.
High response rates in patients with metastatic melanoma have been achieved with combination chemoimmunotherapy. A response rate of 62% in 45 patients has been reported for treatment with dacarbazine, bleomycin, vincristine, lomustine (BOLD) plus interferon alpha (IFN-alpha). We conducted a multicentre phase II study to confirm these results. Melanoma patients with distant metastases were treated as outpatients with dacarbazine 200 mg m(-2) on days 1-5, vincristine 1 mg m(-2) on days 1 and 4, bleomycin 15 mg on days 2 and 5 i.v. and lomustine 80 mg orally on day 1, repeated every 4 weeks. IFN-alpha-2b was initiated s.c. on day 8 at 3 MU daily for 6 weeks, and 6 MU t.i.w. thereafter. Forty-three patients entered the study. The median number of metastatic sites was three (range 1-5), and 81% of patients had visceral metastases. Nine patients had brain metastases, and seven patients were systemically pretreated. Among the 41 patients that were evaluable for response, the response rate was 27% (95% CI 14-3%), with one complete and ten partial remissions. The response rate in 25 previously untreated patients without brain metastases was 40% (95% CI 21-61%). Median duration of response was 6 (range 2-14+) months; median overall survival was 5 (1-26) months. The main toxicity was malaise/fatigue. We confirm that BOLD plus IFN-alpha has activity in metastatic melanoma. The lower response rate in our study compared with the previous report is probably related to patient selection, as in the previous study 46% of patients had stage III disease, whereas all our patients had stage IV disease, which is associated with a worse prognosis.
PMCID: PMC2223935  PMID: 9231931
8.  Acquisition of iron from host proteins by the group A streptococcus. 
Infection and Immunity  1996;64(12):5428-5429.
To identify mammalian iron-binding proteins that can serve as iron sources for Streptococcus pyogenes, the group A streptococcus (GAS), we used a plate assay. Ferritin, hemin, hemoglobin, myoglobin, and catalase can support growth of GAS on iron-depleted medium. However, growth was not detected when iron was provided as iron-saturated transferrin or lactoferrin or bound to cytochrome c. Therefore, it appears that GAS can use the intracellular iron sources available in the human body, which is consistent with its ability to cause tissue destruction during infection.
PMCID: PMC174544  PMID: 8945602
9.  The essential mitotic target of calmodulin is the 110-kilodalton component of the spindle pole body in Saccharomyces cerevisiae. 
Molecular and Cellular Biology  1993;13(12):7913-7924.
Two independent methods identified the spindle pole body component Nuf1p/Spc110p as the essential mitotic target of calmodulin. Extragenic suppressors of cmd1-1 were isolated and found to define three loci, XCM1, XCM2, and XCM3 (extragenic suppressor of cmd1-1). The gene encoding a dominant suppressor allele of XCM1 was cloned. On the basis of DNA sequence analysis, genetic cosegregation, and mutational analysis, XCM1 was identified as NUF1/SPC110. Independently, a C-terminal portion of Nuf1p/Spc110p, amino acid residues 828 to 944, was isolated as a calmodulin-binding protein by the two-hybrid system. As assayed by the two-hybrid system, Nuf1p/Spc110p interacts with wild-type calmodulin and triple-mutant calmodulins defective in binding Ca2+ but not with two mutant calmodulins that confer a temperature-sensitive phenotype. Deletion analysis by the two-hybrid system mapped the calmodulin-binding site of Nuf1p/Spc110p to amino acid residues 900 to 927. Direct binding between calmodulin and Nuf1p/Spc110p was demonstrated by a modified gel overlay assay. Furthermore, indirect immunofluorescence with fixation procedures known to aid visualization of spindle pole body components localized calmodulin to the spindle pole body. Sequence analysis of five suppressor alleles of NUF1/SPC110 indicated that suppression of cmd1-1 occurs by C-terminal truncation of Nuf1p/Spc110p at amino acid residues 856, 863, or 881, thereby removing the calmodulin-binding site.
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PMCID: PMC364863  PMID: 8247006
10.  A dosage-dependent suppressor of a temperature-sensitive calmodulin mutant encodes a protein related to the fork head family of DNA-binding proteins. 
Molecular and Cellular Biology  1993;13(3):1779-1787.
The cmd1-1 mutation of calmodulin causes temperature-sensitive growth in Saccharomyces cerevisiae. We have isolated a dosage-dependent suppressor of cmd1-1, designated HCM1. Twentyfold overexpression of HCM1 permits strains carrying cmd1-1 to grow at temperatures up to and including 34 degrees C but does not suppress the lethality of either cmd1-1 at higher temperatures or the deletion of CMD1. Thus, overexpression of HCM1 does not bypass the requirement for calmodulin but enhances the ability of the mutant calmodulin to function. HCM1 is not essential for growth, but deletion of HCM1 exacerbates the phenotype of a strain carrying cmd1-1. HCM1 is located on chromosome III, which was recently sequenced. Our results correct errors in the published DNA sequence. The putative polypeptide encoded by HCM1 is 564 amino acids long and has a predicted molecular weight of 63,622. Antisera prepared against Hcm1p detect a protein that is overproduced in yeast strains overexpressing HCM1 and has an apparent molecular mass of 65 kDa. Eighty-six amino acid residues in the N terminus of Hcm1p show 50% identity with a DNA-binding region of the fork head family of DNA-binding proteins. When fused to the DNA-binding domain of Gal4p, residues 139 to 511 of Hcm1p can act as a strong activator of transcription. However, overexpression of HCM1 does not affect the expression of calmodulin. Furthermore, Hcm1p does not bind to calmodulin in a gel overlay assay. Thus, overexpression of HCM1 enhances calmodulin function by an apparently indirect mechanism.
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PMCID: PMC359490  PMID: 8441413
11.  Isolation and characterization of transposon mutants of Staphylococcus epidermidis deficient in capsular polysaccharide/adhesin and slime. 
Infection and Immunity  1993;61(2):551-558.
We used transposon (Tn) mutagenesis to study the role of capsular polysaccharide/adhesin (PS/A) and slime in adherence of Staphylococcus epidermidis to catheters. pLTV1, containing Tn917-LTV1, was transformed into S. epidermidis M187 by protoplast fusion with S. aureus RN4220(pLTV1), creating M187(pLTV1). Tn mutants were isolated following growth at 42 degrees C; mutants deficient in PS/A and slime production were selected. PS/A- and slime-deficient Tn mutants had a 10-fold decrease in vitro in the initial phase of adherence to catheters, comparable to levels of strains that do not produce PS/A. Introduction of Tn917-LTV1-interrupted DNA from PS/A-deficient mutant M187sn3 into the parental strain via transformation of protoplasts yielded recipients with inserts identical to those of the Tn mutant that were PS/A and slime deficient. Chromosomal DNA flanking the Tn in mutant M187sn3 was cloned into Escherichia coli. The cloned DNA was found to hybridize to approximately 5-kb EcoRI fragments from the parental strain and from control Tn mutants that express parental levels of PS/A and to either approximately 9- or approximately 14-kb EcoRI fragments from other highly adherent, PS/A-producing strains. Mapping studies demonstrated that in the eight PS/A-deficient mutants that have been isolated, the Tn insertions all occur within a region of approximately 11.6 kb that is defined by three EcoRI sites. These results support previous findings indicating that in S. epidermidis PS/A is involved with in vitro adherence to plastic biomaterials and elaboration of PS/A is closely associated with slime production.
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PMCID: PMC302763  PMID: 8380794
12.  Blood proteins do not promote adherence of coagulase-negative staphylococci to biomaterials. 
Infection and Immunity  1991;59(9):3323-3326.
We studied the effects of in vitro and in vivo coating of catheters with human blood proteins on binding of coagulase-negative staphylococci. Coating resulted in no enhancement of binding. Catheters coated in vitro bound fewer organisms than uncoated catheters. Host proteins do not enhance adherence of coagulase-negative staphylococci to biomaterials.
PMCID: PMC258175  PMID: 1879947
13.  T-cell modulation of the murine antibody response to Neisseria meningitidis group A capsular polysaccharide. 
Infection and Immunity  1988;56(1):259-266.
T-cell modulation of the antibody response of BALB/c mice to group A meningococcal capsular polysaccharide (PS) was examined by using an enzyme-linked immunosorbent assay. An optimal dose (5 micrograms) of antigen induced an immunoglobulin M (IgM) response of short duration; no IgG or IgA antibody could be detected. The capacity to produce serum antibody begins at about 3 weeks of age. Concanavalin A (ConA) inhibited the magnitude of the response by 40 to 60% when given at the time of immunization; it enhanced the response two- to eightfold when given 2 days after PS. T-cell-mediated suppression could be transferred to naive mice by injection of spleen cells from low-dose-primed mice. A secondary antibody response could be induced by immunization with live meningococci. Here, the IgM response was 8- to 10-fold greater than that of mice given an optimal dose of PS; IgG antibody against group A PS increased 1 week after immunization to levels that were 100- to 1,000-fold greater than those of mice immunized with PS. The antibody response could not be augmented by multiple injections of PS; suppression occurred after low-dose priming or hyperimmunization with PS. These studies indicate that the antibody response to PS is not completely T-cell independent; rather, it is inhibited and amplified by T cells.
PMCID: PMC259266  PMID: 3121512
14.  Prairie dog model for antimicrobial agent-induced Clostridium difficile diarrhea. 
Infection and Immunity  1987;55(1):198-200.
We have noted that prairie dogs given cefoxitin develop diarrhea and lose weight yet survive for periods of up to 4 weeks. Therefore, we tested the hypothesis that cefoxitin causes Clostridium difficile cecitis in prairie dogs. Six prairie dogs were given a single intramuscular dose of 100 mg of cefoxitin per kg of body weight, and six control animals received saline; both groups were sacrificed 1 week later. Controls had no diarrhea and lost 2% of their body weight, whereas cefoxitin-treated animals had diarrhea (P less than 0.001) and lost 16% of their body weight (P less than 0.001); one animals died 6 days after cefoxitin challenge. None of the controls yielded C. difficile or had cecal cytotoxin or pseudomembranes detected. Cecal contents from all cefoxitin-treated animals, however, yielded C. difficile (P less than 0.01) and had cecal cytotoxin present (P less than 0.01). Four of five surviving animals also had cecal pseudomembranes present (P less than 0.01). These results demonstrate that in prairie dogs cefoxitin induces C. difficile cecitis. We conclude that the prairie dog is another model for the study of antibiotic-induced diarrhea. The disease in prairie dogs may have a more chronic course than in other animal models of C. difficile-induced diarrhea and may be useful as a model for studying certain aspects of C. difficile-induced diarrhea.
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PMCID: PMC260301  PMID: 3793229
15.  DNA-directed in vitro synthesis and assembly of the form II D-ribulose-1,5-bisphosphate carboxylase/oxygenase from Rhodopseudomonas sphaeroides. 
Journal of Bacteriology  1985;161(1):307-313.
A biochemical analysis of the in vitro assembly of the form II ribulose-1,5-bisphosphate carboxylase/oxygenase from Rhodopseudomonas sphaeroides after transcription and translation from cloned DNA is presented. The predominant enzymatically active oligomeric forms of the in vitro-synthesized and -assembled ribulose-1,5-bisphosphate carboxylase are tetramers and hexamers. Assembly of the monomeric subunits to form active enzyme appears to be dependent on the presence of a minimum number of subunits in the cell extract. Assembly of ribulose-1,5-bisphosphate carboxylase also was observed when the protein-synthesizing extracts were prepared from cells which were partially derepressed for ribulose-1,5-bisphosphate carboxylase expression.
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PMCID: PMC214872  PMID: 3918003
16.  Cloning and characterization of the gene product of the form II ribulose-1,5-bisphosphate carboxylase gene of Rhodopseudomonas sphaeroides. 
Journal of Bacteriology  1985;161(1):469-472.
We report the cloning and characterization of the gene product of the gene for the form II ribulose bisphosphate carboxylase from Rhodopseudomonas sphaeroides. We present evidence that the form II enzyme is encoded by a single gene in R. sphaeroides; however, this gene does hybridize to a second chromosomal locus.
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PMCID: PMC214901  PMID: 3881398
17.  Prolactin and the small intestine. Effect of hyperprolactinaemia on mucosal structure in the rat. 
Gut  1981;22(7):558-565.
To study the mechanism for the adaptive mucosal hyperplasia which occurs independent of luminal nutrition and pancreatico-biliary secretions in isolated Thiry-Vella segments of intestine from lactating rats, and to examine the effects of prolactin on small bowel mucosal structure in the rat, we used two models of experimental hyperprolactinaemia and compared quantitative histology and several markers of mucosal mass in jejunum and ileum from control rats and from test and lactating animals. Hyperprolactinaemia, induced by perphenazine injections (5 mg/kg/day for two or seven weeks) or transplantation of four pituitary glands from donor animals to beneath the renal capsule in the recipient, was confirmed by radioimmunoassay. Proof of its biological activity was obtained by weighing the mammary pads and by demonstrating true breast hyperplasia on histological section. Median serum prolactin levels increased from 50 ng/ml in the controls to 570 ng/ml in the perphenazine treated animals and to 600 ng/ml in the pituitary transplanted rats-levels comparable with those seen in lactation (870 ng/ml). In the lactating rats, there was striking mucosal hyperplasia of both jejunum and ileum but, despite the hyperprolactinaemia, there were no such changes in villus height, crypt depth, or in mucosal wet weight, protein, or DNA/unit length intestine in the perphenazine-injected or pituitary-transplanted animals. We conclude that prolactin is not atrophic to the intestine in rats and that hyperprolactinaemia cannot explain the intestinal adaptive changes of lactation.
PMCID: PMC1419333  PMID: 7262630
18.  relA gene control of the synthesis of lipid A fatty acyl moieties. 
Journal of Bacteriology  1977;130(1):114-117.
The incorporation of [14C]acetate into the fatty acid moieties of lipid A was measured during amino acid starvation of rel+ and relA strains of Escherichia coli K-12. The synthesis of the beta-hydroxymyristate and other fatty acid moieties was inhibited two- to fourfold in rel+ strains, whereas no inhibition was observed in relA strains. The fatty acid compositions of the phospholipids synthesized after amino acid starvation or rel+ and relA strains were also determined.
PMCID: PMC235180  PMID: 323219
19.  Oestrogen facilitates the binding of ubiquitous and liver-enriched nuclear proteins to the apoVLDL II promoter in vivo. 
Nucleic Acids Research  1991;19(1):33-41.
Using genomic and in vitro DNasel footprinting, we have analyzed protein-DNA interactions within the promoter region of the oestrogen-inducible gene encoding chicken apoVLDL II. The footprints coincide with previously detected guanosine-protein contacts in vivo. All footprints identified are present in the apoVLDL II-expressing liver exclusively and absent in hormone-naive liver, spleen and oviduct. They comprise recognition sites for the oestrogen receptor, the ubiquitous COUP-transcription factor, the liver-enriched C/EBP and/or DBP and the liver-specific LF-A1. In vitro, binding of protein to the oestrogen response element (ERE) is excluded by the prior binding of a protein, possibly C/EBP or DBP, to an adjacent element. The recognition sequence of the COUP-TF is also a target for LF-A1. The results suggests that oestrogen-dependent liver specific activation of the apoVLDL II promoter is established by the binding of the oestrogen receptor to EREs and multiple liver-enriched factors (C/EBP, DBP and LF-A1) to their nearby recognition sequences. Apparently, several DNA binding nuclear proteins cooperate to keep the promoter in a state that is accessible for the RNA polymerase complex.
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PMCID: PMC333531  PMID: 2011511
20.  A glutathione reductase mutant of yeast accumulates high levels of oxidized glutathione and requires thioredoxin for growth. 
Molecular Biology of the Cell  1996;7(11):1805-1813.
A glutathione reductase null mutant of Saccharomyces cerevisiae was isolated in a synthetic lethal genetic screen for mutations which confer a requirement for thioredoxin. Yeast mutants that lack glutathione reductase (glr1 delta) accumulate high levels of oxidized glutathione and have a twofold increase in total glutathione. The disulfide form of glutathione increases 200-fold and represents 63% of the total glutathione in a glr1 delta mutant compared with only 6% in wild type. High levels of oxidized glutathione are also observed in a trx1 delta, trx2 delta double mutant (22% of total), in a glr1 delta, trx1 delta double mutant (71% of total), and in a glr1 delta, trx2 delta double mutant (69% of total). Despite the exceptionally high ratio of oxidized/reduced glutathione, the glr1 delta mutant grows with a normal cell cycle. However, either one of the two thioredoxins is essential for growth. Cells lacking both thioredoxins and glutathione reductase are not viable under aerobic conditions and grow poorly anaerobically. In addition, the glr1 delta mutant shows increased sensitivity to the thiol oxidant diamide. The sensitivity to diamide was suppressed by deletion of the TRX2 gene. The genetic analysis of thioredoxin and glutathione reductase in yeast runs counter to previous studies in Escherichia coli and for the first time links thioredoxin with the redox state of glutathione in vivo.
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PMCID: PMC276027  PMID: 8930901

Results 1-21 (21)