Acquisition of Clostridium difficile from the hospital environment

An outbreak of antibiotic-associated colitis that occurred on a ward of a Michigan hospital during February-April, 1984, was studied by bacteriophage-bacteriocin typing. Stools from the seven involved patients yielded Clostridium difficile isolates of types B1537 or Cld7;B1537. C. difficile was recovered from 31.4% of environmental cultures obtained on the ward, and the majority of isolates were types B1537 or Cld7;B1537. When the ward was disinfected with unbuffered hypochlorite (500 parts per million (ppm) available chlorine), surface contamination decreased to 21% of initial levels and the outbreak subsequently ended. Phosphate buffered hypochlorite (1,600 ppm available chlorine, pH 7.6) was even more effective; its use resulted in a 98% reduction in surface contamination. These findings suggest that environmental contamination with C. difficile is important in the epidemiology of antibiotic-associated colitis, and that hypochlorite is effective in eliminating C. difficile from the hospital environment.

Sequence-specific interaction of the Ets1 protein with the long terminal repeat of the human T-lymphotropic virus type I

We recently demonstrated that members of the c-ets proto-oncogene family, Ets1 and Ets2, are sequence-specific transcriptional activators of the human T-lymphotropic virus type I (HTLV-I) long terminal repeat (LTR). We now report that the HTLV-I LTR contains two distinct Ets1-responsive regions, ERR-1 and ERR-2. Expression of Ets1 with reporter plasmids containing ERR-1 or ERR-2 upstream of a basal promoter resulted in an increase in transcriptional activity. By gel mobility shift assay, the interaction of Ets1 with the downstream ERR-1-binding region was found to be more stable than its interaction with the upstream ERR-2 region. By DNase I footprint, gel mobility shift, and methylation interference analyses, ERR-1 was found to contain two Ets1 binding sites, ERE-A and ERE-B. A recombinant Ets1 protein was found to bind with higher affinity to ERE-A than to ERE-B. Binding of Ets1 to these sites appears to result in a specific and sequential protection of a 37-nucleotide sequence of the HTLV-I LTR from -154 to -118. In view of the high-level expression of Ets1 in lymphoid cells, the c-ets proto-oncogenes encode transcription factors which could play an important role in both basal and Tax1-mediated HTLV-I transcription.

Transactivation of the P2 promoter of parathyroid hormone-related protein by human T-cell lymphotropic virus type I Tax1: evidence for the involvement of transcription factor Ets1

Expression of the parathyroid hormone-related protein (PTHrP), a protein that plays a primary role in the development of the humoral hypercalcemia of malignancy, is regulated by two distinct promoters, P1 and P2. PTHrP is overexpressed in lymphocytes from adult T-cell leukemia patients. We now demonstrate that in the human T-cell lymphotropic virus type I-transformed cell line MT-2, RNA synthesis is initiated primarily at the P2 promoter. Furthermore, in cotransfection experiments, Tax1 transactivates the P2 promoter 10- to 12-fold. By using deletion and site-specific point mutations, we have identified a promoter-proximal sequence (positions -72 to -40) which is important for Tax1 transactivation. The PTHrP promoter-proximal element contains two potential overlapping Ets1 binding sites, EBS I and EBS II. Gel shift analysis demonstrated that Ets1 binds specifically to both EBS I and EBS II. Mutation of the consensus GGAA core motif in EBS I abolished binding and Tax1 transactivation in Jurkat T lymphocytes. In Ets1-deficient cells, cotransfection of Tax1 and Ets1 expression plasmids stimulates PTHrP promoter activity. In the absence of Ets1, minimal transactivation of the PTHrP promoter is observed. These data suggest that Ets1 binds to EBS I and cooperates with Tax1 to transactivate the PTHrP P2 promoter.

Involvement of transcription factor YB-1 in human T-cell lymphotropic virus type I basal gene expression

Sequences which control basal human T-cell lymphotropic virus type I (HTLV-I) transcription likely play an important role in initiation and maintenance of virus replication. We previously identified and analyzed a 45-nucleotide sequence (downstream regulatory element 1 [DRE 1]), +195 to +240, at the boundary of the R/U5 region of the long terminal repeat which is required for HTLV-I basal transcription. We identified a protein, p37, which specifically bound to DRE 1. An affinity column fraction, containing p37, stimulated HTLV-I transcription approximately 12-fold in vitro. We now report the identification of a cDNA clone (15B-7), from a Jurkat expression library, that binds specifically to the DRE 1 regulatory sequence. Binding of the cDNA fusion protein, similarly to the results obtained with purified Jurkat protein, was decreased by introduction of site-specific mutations in the DRE 1 regulatory sequence. In vitro transcription and translation of 15B-7 cDNA produced a fusion protein which bound specifically to the HTLV-I +195 to +240 oligonucleotide. The partial cDNA encodes a protein which is homologous to the C-terminal 196 amino acids of the 36-kDa transcription factor, YB-1. Cotransfection of a YB-1 expression plasmid increases HTLV-I basal transcription approximately 14-fold in Jurkat T lymphocytes. On the basis of the molecular weight, DNA-binding characteristics, and in vivo transactivation activity, we suggest that the previously identified DRE 1-binding protein, p37, is YB-1.

Transdominant human T-cell lymphotropic virus type I TAX1 mutant that fails to localize to the nucleus

Human T-cell lymphotropic virus type I (HTLV-I) encodes a 40-kDa nuclear transactivating phosphoprotein, TAX1. The results presented in this study demonstrate that deletion of amino acids 2 through 59 of TAX1 (delta 58 TAX1) decreased transactivation of the HTLV-I long terminal repeat 10- to 20-fold. S1 nuclease analysis revealed that the decrease in transactivation of the HTLV-I long terminal repeat was associated with a lack of RNA synthesis. In contrast to the nuclear localization of the wild-type TAX1 protein, indirect immunofluorescence analysis demonstrated that delta 58 TAX1 failed to localize to the nucleus, indicating that the TAX1 nuclear localization sequence is present in amino acids 2 through 59. Cotransfection of wild-type and mutant TAX1 DNAs resulted in the cytoplasmic accumulation of TAX1 and a 25-fold decrease in transactivation. Although several possibilities which may account for this transdominant effect exist, we favor a model in which delta 58 TAX1 interferes with the nuclear localization of wild-type TAX1 protein, perhaps by forming heterodimer complexes.

Acute cytomegalovirus infection complicated by vascular thrombosis: a case report

We present a case report of a previously healthy adult with cytomegalovirus infection that was complicated by extensive mesenteric arterial and venous thrombosis. To our knowledge, this is the first reported case of this syndrome in an immunocompetent individual who had no predisposing risk factors for thrombosis, and it demonstrates the propensity for cytomegalovirus to be involved in vascular disease.

Transcriptional activation of the human T-lymphotropic virus type I long terminal repeat by functional interaction of Tax1 and Ets1

Transcription regulation of the oncogenic retrovirus human T-lymphotropic virus type I (HTLV-I) involves the composite activity of both viral and cellular transcription factors. The HTLV-I transforming protein, Tax1, modulates the activity of several cellular transcription factors, upregulating the level of viral gene expression. In addition, cellular transcription factors, such as Ets1, independently bind to the viral long terminal repeat in a sequence-specific manner and activate transcription. It was of interest to analyze the possible interaction of Tax1 and Ets1 in viral gene regulation. We now report that Tax1 and Ets1 increase expression from the HTLV-I promoter in a cooperative manner. The level of expression was increased 5- to 10-fold above the combined individual effect of Tax1 and Ets1. S1 nuclease analysis demonstrated that the cooperative effect was due to an increase in the levels of steady-state RNA. The functional interaction between Tax1 and Ets1 required the presence of the Tax1-responsive 21-bp repeat element TRE-1 and the Ets1-responsive element ERR-1. These results suggested the possible interaction of Ets1 with transcriptional regulatory proteins that bind to the 21-bp repeats. This interaction is demonstrated by decreased electrophoretic mobility of specific 21-bp repeat gel shift complexes in the presence of Ets1. Furthermore, interaction of Ets1 with the 21-bp repeat-binding proteins enhances the relative efficiency of binding to the DNA. This cooperative interaction between Ets1 and proteins which bind to the Tax1-responsive 21-bp repeats suggests a possible role for Ets1 in the regulation of viral gene expression.

A 36-kilodalton cellular transcription factor mediates an indirect interaction of human T-cell leukemia/lymphoma virus type I TAX1 with a responsive element in the viral long terminal repeat

The human T-cell leukemia/lymphoma virus type I (HTLV-I) trans activator, TAX1, interacts indirectly with a TAX1-responsive element, TRE-2, located at positions -117 to -163 in the viral long terminal repeat. This report describes the characterization of a 36-kilodalton (kDa) protein identified in HeLa nuclear extract which mediates the interaction of TAX1 with TRE-2. Purification of the protein was achieved by zinc chelate chromatography and preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The renatured 36-kDa protein bound specifically to a TRE-2 oligonucleotide but not to nonfunctional base substitution mutant probes in a gel retardation assay. Renatured proteins of differing molecular weights were unable to form this complex. In addition, the 36-kDa protein specifically activated transcription from the HTLV-I promoter in vitro. Purified TAX1 protein formed a complex with the TRE-2 oligonucleotide in the presence of the 36-kDa protein, suggesting that indirect interaction of TAX1 with the viral long terminal repeat may be one of the mechanisms by which HTLV-I transcription is regulated.

Intraoperative monitoring of danaparoid sodium anticoagulation during cardiovascular operations

PURPOSE

Patients with cardiovascular disorders frequently need anticoagulation for diagnostic studies, surgical procedures, and therapy. Heparin-induced thrombocytopenia is a relatively common complication of heparin therapy that can result in thrombosis and subsequent limb loss or death, necessitating use of alternative anticoagulants.

METHODS

Two patients who needed cardiac surgery had thrombocytopenia induced by exposure to heparin and heparin-coated tubing. Several assays were examined for their ability to monitor intraoperative anticoagulation of a factor Xa inhibitor, danaparoid sodium.

RESULTS

In vitro, celite and kaolin activated dotting times and activated partial thromboplastin time were prolonged linearly in the presence of increasing concentrations of danaparoid sodium. Aprotinin did not alter the linearity of the response but did alter its slope. In vivo, activated clotting times and activated partial thromboplastin time were insensitive to clinically significant changes in danaparoid sodium plasma levels during cardiopulmonary bypass. Correction in activated partial thromboplastin time lagged 2 hours behind clinically important changes in anti-factor Xa levels. Only anti-factor Xa levels were adequate to monitor intraoperative danaparoid sodium levels.

CONCLUSION

Anticoagulation for cardiopulmonary bypass can be successfully performed with danaparoid sodium and intraoperative anti-factor Xa monitoring.

Preimplantation genetic diagnosis (PGD), a collaborative activity of clinical genetic departments and IVF centres

Preimplantation genetic diagnosis (PGD) requires the combined efforts of geneticists and workers in the field of reproductive medicine. This was studied on the basis of a questionnaire, sent to 35 members of the PGD Consortium of the European Society of Human Reproduction and Embryology (ESHRE). A reply was obtained from 20 centres. They represent the majority of activities in the field of PGD in the world. It is obvious that many of the activities (in vitro fertilisation, embryo culture and biopsy) take place in IVF units while others (counselling and diagnosis) are the responsibility of genetic diagnostic centres. The distances between both units vary considerably. In all but one centre sex determination is offered. Aneuploidy screening is offered in 13 out of 20 centres. PGD of translocations and other structural chromosome abnormalities is offered in all but one centre. The number of monogenic diseases offered varies considerably. In comparison to prenatal diagnosis PGD is more expensive. The majority of these costs are due to the IVF or ICSI procedure. The charges for PGD vary between about 600 euro and 4000 euro. In 16 out of 20 centres the parents to be must sign an informed consent form.

Differential precipitation and zinc chelate chromatography purification of biologically active HTLV-I Tax1 expressed in E. coli

A protocol which involves sequential ammonium sulfate precipitation and zinc chelate chromatography to purify the HTLV-I Tax1 protein expressed in E. coli is described. The final Tax1 product is greater than 90% pure and the yield is approximately 1 mg per liter of liquid culture. The purified Tax1 protein is biologically active in indirect in vitro DNA binding assays and cellular NF-kB induction experiments.

A cooperative interaction of human T-cell leukemia virus type 1 Tax with the p21 cyclin-dependent kinase inhibitor activates the human immunodeficiency virus type 1 enhancer

Interactions between the Tax transactivator of human T-cell leukemia virus type 1 (HTLV-1) and a cell cycle regulatory protein have been examined. We report cooperative stimulation of human immunodeficiency virus type 1 gene expression by Tax and a regulator of cell cycle progression, the p21 cyclin-dependent kinase inhibitor (CKI). This cooperativity results from the effect of p21 on transcriptional coactivation by Tax-induced NF-kappaB. This effect was abrogated by a mutation in Tax which specifically eliminated NF-kappaB induction, was inhibitable by IkappaB-alpha, and was markedly reduced in human immunodeficiency virus reporter plasmids with mutant kappaB sites. These studies demonstrate that transcriptional activation by Tax is influenced by cell cycle regulatory proteins.

GLI-2 modulates retroviral gene expression

GLI proteins are involved in the development of mice, humans, zebrafish, Caenorhabditis elegans, Xenopus, and Drosophila. While these zinc finger-containing proteins bind to TG-rich promoter elements and are known to regulate gene expression in C. elegans and Drosophila, mechanistic understanding of how regulation is mediated through naturally occurring transcriptional promoters is lacking. One isoform of human GLI-2 appears to be identical to a factor previously called Tax helper protein (THP), thus named due to its ability to interact with a TG-rich element in the human T-lymphotropic virus type 1 (HTLV-1) enhancer thought to mediate transcriptional stimulation by the Tax protein of HTLV-1. We now demonstrate that, working through its TG-rich binding site and adjacent elements, GLI-2/THP actually suppresses gene expression driven by the HTLV-1 promoter. GLI-2/THP has no effect on the HTLV-2 promoter, activates expression from the promoters of human immunodeficiency virus types 1 and (HIV-1 and -2), and stimulates HIV-1 replication. Both effective suppression and activation of gene expression and viral replication require the first of the five zinc fingers, which is not necessary for DNA binding, to be intact. Thus, not only can GLI-2/THP either activate or suppress gene expression, depending on the promoter, but the same domain (first zinc finger) mediates both effects. These findings suggest a role for GLI-2 in retroviral gene regulation and shed further light on the mechanisms by which GLI proteins regulate naturally occurring promoters.

Induction of nuclear NF-kappa B DNA binding activity after exposure of lymphoid cells to soluble tax1 protein

We demonstrate that purified HTLV-I Tax1 protein can be taken up by 70Z/3 lymphoid cells and localized in both the nuclear and cytoplasmic compartments. Introduction of the Tax1 protein into the growth medium of 70Z/3 cells resulted in the rapid and transient induction of NF-kappa B binding activity in the nuclear fraction. Tax1 activation of NF-kappa B was not sensitive to either staurosporin or prolonged stimulation with the phorbol ester 12-O-tetradecanoylphorbol-13-acetate, suggesting that Tax1-dependent NF-kappa B activation did not require the protein kinase C pathway. Purified Tax1 did not directly increase NF-kappa B binding activity in 70Z/3 cytoplasmic extracts, suggesting that NF-kappa B induction may require cellular factors. Western blot and competitive radioimmunoassays demonstrated that Tax1 protein was present in the tissue culture media of HTLV-I-transformed cell lines. These results show that extracellular Tax1 may regulate cellular gene expression in noninfected cells.

Regulation of parathyroid hormone-related protein (PTHrP) gene expression. Sp1 binds through an inverted CACCC motif and regulates promoter activity in cooperation with Ets1

We have previously shown that mutations in the GGAA core motif of the Ets1 binding site, EBSI, or deletion of EBSI, reduced basal and Tax1 transactivation of the PTHrP P2 promoter. Here we demonstrate that, in addition to EBSI, a CACCC-like motif located between -53 and -58 is required for full basal activity of this promoter in Jurkat T-cells. Site-specific mutations in the CACCC motif decreased promoter activity approximately 5-fold. In an effort to identify transcription factors that bind to the CACCC element, we found that purified human Sp1, as well as Sp1 in HeLa nuclear extract, can specifically bind to a DNA probe that corresponds to the PTHrP-specific sequence between -94 and -34. Gel shift competition studies and DNase I footprinting analyses revealed that Sp1 specifically interacts with the CACCC motif. In the presence of Ets1, the mobility of the Sp1-specific gel shift complex with the PTHrP DNA decreased. DNase I footprint analysis of this gel shift complex showed an extended footprint over both the Sp1 and the Ets1 binding site, demonstrating that Sp1 and Ets1 form a ternary complex with the PTHrP DNA. Cotransfection of an Ets1 and Sp1 expression vector into Drosophila Schneider cells demonstrated that Sp1 can functionally cooperate with Ets1 to transactivate the PTHrP promoter. We conclude from these data that Ets1 and Sp1 can cooperatively regulate PTHrP P2 promoter activity.