c-Myc antagonizes the effect of p53 on apoptosis and p21WAF1 transactivation in K562 leukemia cells

c-myc protooncogene positively regulates cell proliferation and overexpression of c-myc is found in many solid tumors and leukemias. In the present study we used the K562 human myeloid leukemia cell line as a model to study the functional interaction between c-Myc and p53. Using two different methods, we generated K562 transfectant cell lines with conditional expression of either c-Myc or p53. The cells expressed the p53Vall35 mutant, which adopts a wild-type conformation at 32 degrees C, while c-Myc induction was achieved with a zinc-inducible expression vector. We found that p53 in wild-type conformation induces growth arrest and apoptosis of K562. Expression of c-Myc significantly attenuated apoptosis and impaired the transcriptional activity of p53 on p21WAF1, Bax and cytomegalovirus promoters. The impairment of p21WAF1 transactivation by c-Myc was confirmed by transfection of a c-Myc-estrogen receptor fusion protein and by induction of c-myc by zinc in transfected cells. Also, p53-mediated up-regulation of p21WAF1 mRNA protein were significantly reduced by c-Myc, while Bax levels were unaffected. Consistently, c-Myc increased cyclin-dependent kinase 2 activity in K562 cells expressing p53 in wild-type conformation. These results suggest that c-Myc overexpression may antagonize the pro-apoptotic function of p53, thus providing a molecular mechanism for the frequently observed deregulation of c-myc in human cancer.

Characterization of the sialidase molecular defects in sialidosis patients suggests the structural organization of the lysosomal multienzyme complex

Sialidosis is an autosomal recessive disease caused by the genetic deficiency of lysosomal sialidase, which catalyzes the hydrolysis of sialoglycoconjugates. The disease is associated with progressive impaired vision, macular cherry-red spots and myoclonus (sialidosis type I) or with skeletal dysplasia, Hurler-like phenotype, dysostosis multiplex, mental retardation and hepatosplenomegaly (sialidosis type II). We have analyzed the genomic DNA from nine sialidosis patients of multiple ethnic origin in order to find mutations responsible for the enzyme deficiency. The activity of the identified variants was studied by transgenic expression. One patient had a frameshift mutation (G623delG deletion), which introduced a stop codon, truncating 113 amino acids. All others had missense mutations: G679G-->A (Gly227Arg), C893C-->T (Ala298Val), G203G-->T (Gly68Val), A544A-->G (Ser182Gly) C808C-->T (Leu270Phe) and G982G-->A (Gly328Ser). We have modeled the three-dimensional structure of sialidase based on the atomic coordinates of the homologous bacterial sialidases, located the positions of mutations and estimated their potential effect. This analysis showed that five mutations are clustered in one region on the surface of the sialidase molecule. These mutations dramatically reduce the enzyme activity and cause a rapid intralysosomal degradation of the expressed protein. We hypothesize that this region may be involved in the interface of sialidase binding with lysosomal cathepsin A and/or beta-galactosidase in their high-molecular-weight complex required for the expression of sialidase activity in the lysosome.

Myeloid leukemia cell growth and differentiation are independent of mitogen-activated protein kinase ERK1/2 activation

The mitogen-activated protein kinase ERK1/2 pathway is essential in the control of cell proliferation and differentiation in most cellular systems. As such, it has been considered a potential target for antineoplastic therapy. For this purpose, we have examined the role of ERK activation in myeloid leukemia cell growth and differentiation. Using a representative set of myeloid leukemia cell lines, we show that cell proliferation was not accompanied by increases on ERK1/2 activation, and mitogenic stimulation did not enhance ERK activity. Moreover, abolition of ERK function by the inhibitor PD98059 or by a dominant inhibitory mutant ERK2 had no significant effects on proliferation. With the aid of various differentiation inducers, we found that within the same cell line, differentiation to a given lineage could occur with and without ERK1/2 activation, depending on the stimulus. Also, a differentiator could have the same effect in the presence or absence of ERK stimulation, depending on the cell line. ERK inhibition did not affect the differentiation elicited by stimuli whose effects were accompanied by ERK activation. Finally, constitutive ERK activity was also ineffective on proliferation and differentiation. Thus, our results indicate that ERK1/2 activation is not an essential requirement for leukemic cell growth and differentiation.

Activation of a pro-apoptotic amplification loop through inhibition of NF-kappaB-dependent survival signals by caspase-mediated inactivation of RIP

Death domain containing members of the tumor necrosis factor receptor (TNFR) superfamily can induce apoptosis or cell activation. However, the mechanisms by which these opposing programs are selected remain unclear. Frequently, NF-kappaB activation conveys protection against cell death. We show that the serine/threonine kinase RIP that is required for TNF-induced NF-kappaB activation is processed by caspase-8 into a dominant-negative (DN) fragment during death receptor-induced apoptosis, thereby leading to a blockade of NF-kappaB-mediated anti-apoptotic signals. Our results suggest that cleavage of RIP is part of an amplification loop which is triggered by Fas and most likely by other death receptors.

Characterization of the LI818 polypeptide from the green unicellular alga Chlamydomonas reinhardtii

The LI818 gene from Chlamydomonas encodes a polypeptide that is related to the chlorophyll a/b-binding proteins (CAB) of higher plants and green algae. However, despite this relatedness, LI818 gene expression is not coordinated with that of cab genes and is regulated differently by light, suggesting a different role for LI818 polypeptide. We show here that, in contrast to CAB polypeptides, LI818 polypeptide is not tightly embedded into the thylakoid membranes and is localized in stroma-exposed regions. Moreover, during chloroplast development, LI818 polypeptide accumulates before CAB polypeptides. We also show that the LI818 polypeptide forms with certain chlorophyll a/c-binding proteins (CAC) from the haptophyte Isochrysis galbana and the diatom Cyclotella cryptica a natural group that is distinct from those constituted by CAB, CAC and the chlorophyll a/a-binding proteins (CAA). Such an association suggests a very ancient origin for this group of polypeptides, which predates the division of the early photosynthetic eukaryotes into green (chlorophyte), red (rhodophyte) and brown (chromophyte) algae. Possible roles for the LI818 polypeptide are discussed.

Chlorhexidine compared with povidone-iodine as skin preparation before blood culture. A randomized, controlled trial

BACKGROUND

Chlorhexidine is better than povidone-iodine for care of catheter sites, but it is not known whether chlorhexidine is superior in reducing blood culture contamination.

OBJECTIVE

To determine whether alcoholic chlorhexidine is a more effective skin antiseptic for collection of blood cultures than aqueous povidone-iodine.

DESIGN

Randomized, controlled trial.

SETTING

Three adult intensive care units in a French university hospital.

PATIENTS

403 adults who had at least one blood culture drawn through a peripheral vein.

INTERVENTIONS

Patients were randomly assigned to receive skin preparation with an aqueous solution of 10% povidone-iodine or an alcoholic solution of 0.5% chlorhexidine before phlebotomy.

MEASUREMENTS

Contamination rates of blood cultures.

RESULTS

Of 2041 blood cultures collected in 403 patients, 124 yielded pathogens. Chlorhexidine reduced the incidence of blood culture contamination more than povidone-iodine (14 of 1019 cultures [1.4%] compared with 34 of 1022 cultures [3.3%]; odds ratio, 0.40 [95% CI, 0.21 to 0.75]; P = 0.004).

CONCLUSION

Skin preparation with alcoholic chlorhexidine is more efficacious than skin preparation with aqueous povidone-iodine in reducing contamination of blood cultures.

Primary lymphoplasmacytoid lymphoma of the trachea with immunoglobulin G paraprotein

A primary tracheal lymphoma with immunoglobulin G (IgG)-associated monoclonal serum paraprotein treated with surgery and chemotherapy is reported. As far as we know this is the first lymphoplasmacytoid lymphoma reported in the tracheobronchial tree and the first with a serum and tissue IgG monoclonal paraprotein. Differential diagnosis must be made essentially with extramedullary plasmacytoma and mucosa-associated lymphoid tissue lymphoma. CD-45RB strong positivity and the absence of lymphoepithelial lesions may help to differentiate lymphoplasmacytoid lymphoma from them. We expand the spectrum of lymphoid lesions with plasmacytoid features that can occur in the tracheobronchial tract.

Translocation (10;11)(p13;p15) in an infant acute myeloid leukemia with MLL gene rearrangement

Molecular rearrangements of the MLL gene at the 11q23 region have been identified in most cases of infant leukemia, regardless of the phenotype. We present a case of acute myeloid leukemia which coexpressed myeloid and lymphoid markers in a 12-month-old girl. Karyotype analysis revealed the presence of a thus far unreported translocation t(10;11)(p13;p15). Although no 11q23 abnormalities were cytogenetically detectable, an MLL gene molecular rearrangement was found.

[Fenfluramines and cardiac valvular lesions]

We report cardiac valvulopathy occurring after prolonged intake of anorectic drugs containing fenfluramine (Fen) and/or dexfenfluramine (D-Fen) in 14 patients whose evolution was followed by Doppler echocardiography. A relation between these drugs and valvular regurgitation was first suspected after 4 cases reported in 1991-1992 and confirmed after 3 more patients in 1993-94-95, who were taken D-Fen or Fen alone. All were women, aged 42 to 73 years. Patient 1 to 7 had been taking Fen and/or D-Fen for 14 to 52 months. Patients 8 to 14 had been taking a mixture of Fen and/or D-Fen, diethylpropion and chinese-herbs for 3 to 69 months. These last 7 patients developed renal failure requiring hemodialysis or peritoneal dialysis in 5 and subsequent renal transplantation in 4. All presented with cardiac murmur(s) and some with dyspnea or palpitations. An initial echocardiography was performed at the time of diagnosis, and was repeated annually for a follow-up period extending to 8 years. We conclude that a relation between Fen and/or D-Fen and the outbreak of valvular heart disease is identified in our patients, confirming previous findings. The nephrotoxicity observed in 7 patients is due to the "chinese-herbs". When Fen and/or D-Fen are stopped and proper therapy initiated, the cardiac symptoms may stabilize or even subside, though slowly. Hemodynamic unstability and/or infection appear to be an aggravating factor. These patient's follow up must be prolonged for several years and is readily achieved with echocardiography. Systematic screening of all patients having taken Fen and/or D-Fen must be performed, as renal and urinary screening for all patients having taken chinese-herbs. Endocardial prophylaxis must always be prescribed.

Forssman penta- and tetraglycosylceramide are xenoantigens of ostrich kidney and liver

The heterophile antigens Galalpha1-->3Gal and N-glycolylneuraminic acid are the major obstacle to grafting mammal organs, especially from pig, to man. Lack of expression of these common xenoantigens by birds has raised interest in ostrich as a potential organ donor for xenotransplantation. Glycosphingolipids of ostrich liver and kidney were investigated for their carbohydrate determinants. Both organs were found similar in their glycolipid composition with three major species, mono-, di-, and pentaglycosylceramide. The pentaglycosylceramide was characterized as the Forssman antigen. In both organs, the ceramide portion was highly hydroxylated with prevalence of alpha-hydroxylated fatty acids, C18 phytosphingosine in kidney and C18 sphingosine in liver Forssman glycolipid. These data indicate that hydroxylation of kidney glycosphingolipids, which is found in mammals, has been maintained since the divergence of birds from other vertebrates. Characterization of a minor glycolipid as a Forssman tetraglycosylceramide built on the galabiosylceramide core indicates that the Forssman tetraglycosylceramide also exists in vivo. Its precursors, galactosyl- and galabiosylceramide, were characterized in kidney and liver. The Forssman antigen is the third heterophile antigen against which man raises natural antibodies. Its localization in the vascular endothelium and connective tissue makes ostrich an unpromising organ or cell donor for xenotransplantation to man.

Regulation of c-Myc and Max in megakaryocytic and monocytic-macrophagic differentiation of K562 cells induced by protein kinase C modifiers: c-Myc is down-regulated but does not inhibit differentiation

We have studied the regulation and role of c-Myc and Max in the differentiation pathways induced in K562 cells by 12-O-tetradecanoyl phorbol-13 acetate (TPA) and staurosporine, an activator and inhibitor, respectively, of protein kinase C (PKC). We found that staurosporine induced megakaryocytic differentiation, as revealed by the cellular ultrastructure, platelet formation, and DNA endoreduplication. In contrast, TPA induced a differentiated phenotype that more closely resembled that of the monocyte-macrophage lineage. c-myc expression was down-regulated in K562 differentiated by both TPA and staurosporine, whereas max expression did not change in either case. Although PKC enzymatic activity was low in cells terminally differentiated with TPA and staurosporine, inhibition of PKC activity by itself did not induce c-myc down-regulation. We conclude that the c-myc gene is switched off as a consequence of the differentiation process triggered by these drugs in a manner independent from PKC. Ectopic overexpression of c-Myc in K562 cells did not affect the monocytic-macrophagic and megakaryocytic differentiation, indicating that c-Myc suppression is not required for these processes in K562. Similarly, both differentiation pathways were not affected by Max overexpression or by concomitant overexpression of c-Myc and Max. This result is in contrast with the inhibition of erythroid differentiation of K562 exerted by c-Myc, suggesting divergent roles for c-Myc/Max, depending on the differentiation pathway.

Apoptosis and mitotic arrest are two independent effects of the protein phosphatases inhibitor okadaic acid in K562 leukemia cells

Treatment of human myeloid leukemia K562 cells with the serine/threonine protein phosphatases inhibitor okadaic acid induced mitotic arrest followed by apoptosis in a synchronized manner. The effect was observed at drug concentrations that inhibited the protein phosphatase type 2A but not type 1. We investigated whether apoptosis was a consequence of the preceding mitosis arrest or was induced independently by okadaic acid. We found that (1) apoptosis, but not mitotic arrest, was inhibited in cells with constitutive expression of Bcl-2; (2) pretreatment of cells with the DNA synthesis inhibitor hydroxyurea blocked the mitotic arrest but not the apoptosis mediated by okadaic acid; (3) down-regulation of c-myc gene was associated with apoptosis, but not with mitotic arrest; and (4) inhibition of protein synthesis abrogated mitotic arrest, but not apoptosis. The results suggest that inhibition of protein phosphatase 2A by okadaic acid provokes mitotic arrest and apoptosis of leukemia cells by independent mechanisms.

Lymphoid hypoplasia and somatic cloning

BACKGROUND

Adult somatic cloning by nuclear transfer is associated with high rate of perinatal mortality but there is still no evidence that nuclear transfer itself is responsible for these failures. We report on a longlasting defect linked to somatic cloning.

METHODS

Skin cells grown from an ear biopsy specimen from a 15-day-old calf were used as a source of nuclei. The donor animal was a clone of three females obtained from embryonic cells. Clinical examination, haematological, and biochemical profiles, and echocardiography of the somatic clone were done from birth to death.

FINDINGS

After 6 weeks of normal development, the somatic cloned calf had a sudden and rapid fall in lymphocyte count and a decrease in haemoglobin. The calf died on day 51 from severe anaemia. Necropsy revealed no abnormality except thymic atrophy and lymphoid hypoplasia.

INTERPRETATION

Somatic cloning may be the cause of long-lasting deleterious effects. Our observation should be taken into account in debates on reproductive cloning in human beings.

Effects of epinephrine, norepinephrine, or the combination of norepinephrine and dobutamine on gastric mucosa in septic shock

OBJECTIVES

To compare in the same patient with septic shock, respective effects of epinephrine, norepinephrine, and the combination of norepinephrine and dobutamine (5 microg/kg/min) on systemic hemodynamic parameters and gastric mucosal perfusion using gastric tonometry and laser-Doppler flowmetry techniques.

DESIGN

Prospective, controlled, randomized, crossover study.

SETTING

University hospital intensive care unit.

PATIENTS

Twelve patients with septic shock.

INTERVENTIONS

Each patient received in a random succession epinephrine, norepinephrine, and norepinephrine plus dobutamine. Dosages of epinephrine and norepinephrine were adjusted to achieve a mean arterial pressure between 70 and 80 mm Hg. A laser-Doppler probe and a tonometer were introduced into the gastric lumen.

MEASUREMENTS AND MAIN RESULTS

The increase in gastric mucosal perfusion detected by laser-Doppler flowmetry was higher with epinephrine and the combination of norepinephrine and dobutamine than with norepinephrine alone (p < .05). In addition, the ratio of gastric mucosal perfusion (local oxygen delivery) to systemic oxygen delivery was increased after norepinephrine plus dobutamine as compared with norepinephrine alone and epinephrine (p< .05). Although values of intramucosal pH and gastroarterial PCO2 tended to be higher with norepinephrine plus dobutamine compared with those obtained with norepinephrine and epinephrine, differences were not statistically significant.

CONCLUSIONS

For the same mean arterial pressure in patients with septic shock, our study showed that administration of epinephrine increased gastric mucosal perfusion more than norepinephrine administration alone. Addition of dobutamine (5 microg/kg/ min) to norepinephrine improved gastric mucosal perfusion. This result could be explained by a vasodilating effect of dobutamine on gastric mucosal microcirculation.

Purification, cDNA cloning, and expression of a new human blood plasma glutamate carboxypeptidase homologous to N-acetyl-aspartyl-alpha-glutamate carboxypeptidase/prostate-specific membrane antigen

We describe the identification, cDNA cloning, and biochemical characterization of a new human blood plasma glutamate carboxypeptidase (PGCP). PGCP was co-purified from human placenta with lysosomal carboxypeptidase, cathepsin A, lysosomal endopeptidase, cathepsin D, and a gamma-interferon-inducible protein, IP-30, using an affinity chromatography on a Phe-Leu-agarose column. A PGCP cDNA was obtained as an expressed sequence tag clone and completed at 5'-end by rapid amplification of cDNA ends polymerase chain reaction. The cDNA contained a 1623-base pair open reading frame predicting a 541-amino acid protein, with five putative Asn glycosylation sites and a 21-residue signal peptide. PGCP showed significant amino acid sequence homology to several cocatalytic metallopeptidases including a glutamate carboxypeptidase II also known as N-acetyl-aspartyl-alpha-glutamate carboxypeptidase or as prostate-specific membrane antigen and expressed glutamate carboxypeptidase activity. Expression of the PGCP cDNA in COS-1 cells, followed by Western blotting and metabolic labeling showed that PGCP is synthesized as a 62-kDa precursor, which is processed to a 56-kDa mature form containing two Asn-linked oligosaccharide chains. The mature form of PGCP was secreted into the culture medium, which is consistent with its intracellular localization in secretion granules. In humans, PGCP is found principally in blood plasma, suggesting a potential role in the metabolism of secreted peptides.

Characterization of two monoclonal antibodies against porcine VCAM-1

Immunization of mice with TNF alpha-activated porcine endothelial cells led to the characterization of two monoclonal antibodies (MAbs), 5F3 and 8A7, specific for porcine VCAM-1. Upon flow cytometry, both antibodies increasingly labeled endothelial cells according to their degree of activation. They bound a band of MW 80 kDa on Western blots of endothelial cells, which is the apparent molecular weight of porcine VCAM-1. It was determined by surface plasmon resonance that the antibodies are directed to different antigenic sites. It was also found that 5F3 competes for binding the antigen with a MAb previously characterized as binding domain 1 of porcine VCAM-1. Subsequently, 5F3, but not 8A7, was found to inhibit the adhesion of human B lymphocyte Ramos cells to porcine endothelial cells in vitro. These antibodies, which do not cross-react with human VCAM-1, might be useful for diagnostic or therapeutic purposes in xenotransplantation.

Clinical use of respiratory changes in arterial pulse pressure to monitor the hemodynamic effects of PEEP

In ventilated patients with acute lung injury (ALI) we investigated whether respiratory changes in arterial pulse pressure (DeltaPP) could be related to the effects of PEEP and fluid loading (FL) on cardiac index (CI). Measurements were performed before and after application of a PEEP (10 cm H2O) in 14 patients. When the PEEP-induced decrease in CI was > 10% (six patients), measurements were also performed after FL. Maximal (PPmax) and minimal (PPmin) values of pulse pressure were determined over one respiratory cycle and DeltaPP was calculated: DeltaPP (%) = 100 x ((PPmax - PPmin)/ ([PPmax + PPmin]/2)). PEEP decreased CI from 4.2 +/- 1.1 to 3.8 +/- 1.3 L/min/m2 (p < 0.01) and increased DeltaPP from 9 +/- 7 to 16 +/- 13% (p < 0.01). The PEEP-induced changes in CI correlated with DeltaPP on ZEEP (r = -0.91, p < 0.001) and with the PEEP-induced increase in DeltaPP (r = -0.79, p < 0.001). FL increased CI from 3.5 +/- 1.1 to 4.2 +/- 0.9 L/min/m2 (p < 0.05) and decreased DeltaPP from 27 +/- 13 to 14 +/- 9% (p < 0.05). The FL-induced changes in CI correlated with DeltaPP before FL (r = 0.97, p < 0.01) and with the FL-induced decrease in DeltaPP (r = -0.85, p < 0.05). In ventilated patients with ALI, DeltaPP may be useful in predicting and assessing the hemodynamic effects of PEEP and FL.

Topical indomethacin solution versus dexamethasone solution for treatment of inflamed pterygium and pinguecula: a prospective randomized clinical study

PURPOSE

To compare the effect of topical indomethacin 0.1% solution with the effect of topical dexamethasone 0.1% phosphate solution on signs and symptoms of inflamed pterygium and pinguecula.

METHODS

Of 50 consecutive patients who had inflamed pterygia (n = 17) or pingueculae (n = 33), met the study criteria, and signed an informed consent, one eye of each patient was evaluated in a comparative, prospective, randomized, double-masked, controlled study. Objective signs (conjunctival congestion, redness and edema, and staining of cornea) and subjective complaints (photophobia, pain, foreign-body sensation, discomfort, and tearing) were evaluated and scored. We also evaluated "total signs," "total symptoms," and "total score." Group 1 (n = 25) received topical indomethacin 0.1% solution, and group 2 (n = 25) received a topical dexamethasone phosphate 0.1% solution six times daily for 3 days, then four times daily over the following 11 days. Patients were examined before treatment, on days 3, 7, and 14 after the treatment was initiated, and 2 and 4 weeks after the treatment was discontinued.

RESULTS

In both groups, the scores for "total signs," "total symptoms," and "total score" were significantly lower (P = .001) by day 14. There were no differences between groups 1 and 2 for "total signs," "total symptoms," and "total score" at days 3, 7, and 14 (P = .07 to P = .88). After treatment was discontinued, the dexamethasone-treated group experienced a significantly greater recurrence of "total signs" (P = .023 at day 30, P = .02 at day 45), but there was no statistically significant difference in "total symptoms" and "total score." Patients in group 2 reported more stinging after drops were administered than patients in group 1 (P = .002).

CONCLUSIONS

This study indicates that topical indomethacin 0.1% solution is as effective as topical dexamethasone phosphate 0.1% solution for the treatment of inflamed pterygium and pinguecula and, therefore, is suggested as an effective treatment for these conditions.

[Organ procurement from cardiac arrest donors: outcome of kidney grafts and recommendations]

OBJECTIVES

To compare literature data with results obtained with organs procured from donors who died from cardiac arrest and to make proposals for this mode of organ procurement in France.

METHODS

Over the last 10 years, 10 organ donors (2%) among a series of 486 donors in a state of brain death, had died of cardiac arrest. The arrest were perfused with double-balloon catheters. The outcome of the subsequent kidney grafts was compared with data in the literature.

RESULTS

Fifteen of the 18 kidneys from cardiac arrest donors were functioning 1 month after implantation compared with 17 of the 20 kidneys from braindeath donors with beating hearts. The rate of acute tubular necrosis was 55% in the cardiac arrest kidneys and 40% in the beating-heart kidneys. Serum creatinine at 1 yeart was 145 +/- 69 mumol/l 17 +/- 29 mumol/l respectively.

DISCUSSION

These results and those reported in the literature demonstrate that kidney procurement from cardiac arrest donors is feasible. If intensive care and surgery units are well organized, this type of organ procurement could provide a larger number of organs for transplantation. Emergency teams must be available for preparing and transferring the organs.