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M Schapira

Publications and source records attributed to M Schapira.

At least 37 records · Page 2Linked to original sources
PubMed1998

Relationship between cleaved L-selectin levels and the outcome of acute myeloid leukemia.

High plasma levels of the shed form of L-selectin (sL-selectin) are frequently detectable in acute myeloid leukemia (AML). sL-selectin can inhibit blast cell adhesion to vascular endothelium and may thereby influence the phenotype of AML. In this study, we have investigated the relationship between sL-selectin levels and clinical presentation or disease outcome in 100 patients with AML. Fifty-eight patients were found to have sL-selectin levels >/=3.12 microgram/mL (>/=3 SD above the mean of healthy controls: "increased"). Patients with extramedullary disease such as lymphadenopathies, splenomegaly, hepatomegaly, and/or muco-cutaneous infiltration had significantly increased sL-selectin levels (P < .001). sL-selectin levels were significantly heterogeneous in the French-American-British subtypes (P = .0003). Patients with "normal" sL-selectin levels had higher probability of achieving complete remission (CR) than with "increased" levels: 81% versus 64%, respectively (P = .06). When adjusting for clinically relevant covariates predictive for CR (sex, age, Auer rods), "normal" sL-selectin levels were significantly associated with CR (odds ratio, 3.08; 95% confidence interval [CI], 1.10 to 8.58; P = .03). Moreover, patients with "increased" sL-selectin levels (>/=3.12 microgram/mL) had shorter event-free survival (EFS) (median 7.3 v 12 months, P = .008) and overall survival (median 1 v 2.05 years, P = .03) than patients with sL-selectin <3.12 microgram/mL. Multivariate statistical analysis (adjusted for age and presence of Auer rods) indicated that sL-selectin was an independent prognostic factor for EFS (hazard ratio [HR], 1.96; 95% CI, 1.21 to 3.17, P = .006) and overall survival (HR, 1.80; 95% CI, 1.09 to 2.98; P = .02). Thus, plasma sL-selectin may be a useful prognostic marker in the evaluation of AML at diagnosis.

Acute Disease↗
PubMed1998

Subunit rearrangement accompanies sequence-specific DNA binding by the bovine papillomavirus-1 E2 protein.

The 2.5 A crystal structures of the DNA-binding domain of the E2 protein from bovine papillomavirus strain 1 and its complex with DNA are presented. E2 is a transcriptional regulatory protein that is also involved in viral DNA replication. It is the structural prototype for a novel class of DNA-binding proteins: dimeric beta-barrels with surface alpha-helices that serve as recognition helices. These helices contain the amino-acid residues involved in sequence-specifying interactions. The E2 proteins from different papillomavirus strains recognize and bind to the same consensus 12 base-pair DNA sequence. However, recent evidence from solution studies points to differences in the mechanisms by which E2 from the related viral strains bovine papillomavirus-1 and human papillomavirus-16 discriminate between DNA targets based on non-contacted nucleotide sequences. This report provides evidence that sequence-specific DNA-binding is accompanied by a rearrangement of protein subunits and deformation of the DNA. These results suggest that, along with DNA sequence-dependent conformational properties, protein subunit orientation plays a significant role in the mechanisms of target selection utilized by E2.

Amino Acid Sequence↗
PubMed1997

Monocyte adhesion to activated aortic endothelium: role of L-selectin and heparan sulfate proteoglycans.

This study examines the role of L-selectin in monocyte adhesion to arterial endothelium, a key pathogenic event of atherosclerosis. Using a nonstatic (rotation) adhesion assay, we observed that monocyte binding to bovine aortic endothelium at 4 degrees C increased four to nine times upon endothelium activation with tumor necrosis factor (TNF)-alpha. mAb-blocking experiments demonstrated that L-selectin mediates a major part (64 +/- 18%) of monocyte attachment. Videomicroscopy experiments performed under flow indicated that monocytes abruptly halted on 8-h TNF-alpha-activated aortic endothelium, approximately 80% of monocyte attachment being mediated by L-selectin. Flow cytometric studies with a L-selectin/IgM heavy chain chimeric protein showed calcium-dependent L-selectin binding to cytokine-activated and, unexpectedly, unactivated aortic cells. Soluble L-selectin binding was completely inhibited by anti-L-selectin mAb or by aortic cell exposure to trypsin. Experiments with cycloheximide, chlorate, or neuraminidase showed that protein synthesis and sulfate groups, but not sialic acid residues, were essential for L-selectin counterreceptor function. Moreover, heparin lyases partially inhibited soluble L-selectin binding to cytokine-activated aortic cells, whereas a stronger inhibition was seen with unstimulated endothelial cells, suggesting that cytokine activation could induce the expression of additional ligand(s) for L-selectin, distinct from heparan sulfate proteoglycans. Under flow, endothelial cell treatment with heparinase inhibited by approximately 80% monocyte attachment to TNF-alpha-activated aortic endothelium, indicating a major role for heparan sulfate proteoglycans in monocyte-endothelial interactions. Thus, L-selectin mediates monocyte attachment to activated aortic endothelium, and heparan sulfate proteoglycans serve as arterial ligands for monocyte L-selectin.

Animals↗
PubMed1997

Regulation of C1-inhibitor function by binding to type IV collagen and heparin.

Serpins inhibit proteinases by a branched pathway, in which an intermediate serpin-proteinase complex can either form a stable covalent serpin-proteinase complex or produce reactive center cleaved serpin in a substrate reaction. It was tested whether these competing reactions could be regulated for the serpin C1-inhibitor by ligand binding. C1-inhibitor bound to type IV collagen, laminin, and entactin. Type IV collagen (10 microg/ml) caused an increase in the stoichiometry of inhibition for C1s inhibition by C1-inhibitor to 1.48 from 1.09 in the absence of ligand. A dose-dependent increase in the stoichiometry up to 1.27 in the presence of 100 microg/ml heparin was also observed. At low ionic strength the stoichiometry increased to 2.55. These data provide the first report that C1-inhibitor can bind to type IV collagen and also show that C 1-inhibitor can be regulated by ligand binding.

Binding, Competitive↗
PubMed1997

Hypoxic hepatitis caused by severe hypoxemia from obstructive sleep apnea.

Cardiac and circulatory failure are the main causes of hypoxic hepatitis. In a prospective study of 142 cases of hypoxic hepatitis collected during a 10-year period, we encountered two cases resulting from extreme arterial hypoxemia without congestive heart failure, cor pulmonale, or circulatory failure. Both patients were morbidly obese women admitted to the intensive care unit for carbonarcosis. Oxygen arterial saturation was very low, less than 35% in both patients, but there was no history of cardiac or respiratory failure and no clinical evidence of circulatory failure. Cardiac function, evaluated by isotopic scintigraphy, was normal. After the episode of hypoxic hepatitis, a diagnosis of obstructive sleep apnea was made clinically and confirmed by performing nocturnal oximetry, which showed multiple episodes of oxygen desaturation in both patients. Polysonography could be performed in one case and was typical of obstructive sleep apnea. Liver ischemia is the main mechanism leading to hypoxic hepatitis. More recently, the role of passive congestion of the liver has been emphasized. Arterial hypoxemia, however, is generally considered to be a minor factor. Our two cases support the hypothesis that severe arterial hypoxemia may lead to hypoxic hepatitis even in the absence of cardiac and circulatory failure.

Aged↗
PubMed1996

Human immunoglobulins produced in hu-PBL-SCID mice are polyclonal early after xenotransplantation.

Xenotransplantation of human peripheral blood leukocytes (hu-PBL) to severe combined immune-deficient (SCID, hu-PBL-SCID) mice leads to human immunoglobulin (Ig) production in the animals. Here we used a sensitive high-resolution two-dimensional electrophoresis (2D-PAGE) technique to separate, and to analyze, Ig gamma and light chains in sera from SCID mice given hu-PBL for less than 35 days. Human Igs in the model appeared polyclonal until 3 weeks after cell transfer. After this period, oligoclonal Igs progressively replaced this polyclonal background. The 2D-PAGE pattern evolution of human Igs was similar when hu-PBL originated from donors with or without previous contact with the Epstein-Barr virus. The broad diversity of human Igs, and therefore the large expressed B cell repertoire, in hu-PBL-SCID mice during a period that allows manipulation (such as immunization) of the human graft has evident implication for the use of this model in the generation of specific antibodies of desired specificity.

Animals↗
PubMed1996

P-selectin glycoprotein ligand 1 is a ligand for L-selectin on neutrophils, monocytes, and CD34+ hematopoietic progenitor cells.

Selectins play a critical role in initiating leukocyte binding to vascular endothelium. In addition, in vitro experiments have shown that neutrophils use L-selectin to roll on adherent neutrophils, suggesting that they express a nonvascular L-selectin ligand. Using a L-selectin/IgM heavy chain (mu) chimeric protein as an immunocytological probe, we show here that L-selectin can bind to neutrophils, monocytes, CD34+ hematopoietic progenitors, and HL-60 and KG-1 myeloid cells. The interaction between L-selectin and leukocytes was protease sensitive and calcium dependent, and abolished by cell treatment with neuraminidase, chlorate, or O-sialoglycoprotein endopeptidase. These results revealed common features between leukocyte L-selectin ligand and the mucin-like P-selectin glycoprotein ligand 1 (PSGL-1), which mediates neutrophil rolling on P- and E-selectin. The possibility that PSGL-1 could be a ligand for L-selectin was further supported by the ability of P-selectin/mu chimera to inhibit L-selectin/mu binding to leukocytes and by the complete inhibition of both selectin interactions with myeloid cells treated with mocarhagin, a cobra venom metalloproteinase that cleaves the amino terminus of PSGL-1 at Tyr-51. Finally, the abrogation of L- and P-selectin binding to myeloid cells treated with a polyclonal antibody, raised against a peptide corresponding to the amino acid residues 42-56 of PSGL-1, indicated that L- and P-selectin interact with a domain located at the amino-terminal end of PSGL-1. The ability of the anti-PSGL-1 mAb PL-1 to inhibit L- and P-selectin binding to KG-1 cells further supported that possibility. Thus, apart from being involved in neutrophil rolling on P- and E-selectin, PSGL-1 also plays a critical role in mediating neutrophil attachment to adherent neutrophils. Interaction between L-selectin and PSGL-1 may be of major importance for increasing leukocyte recruitment at inflammatory sites.

Antigens, CD34↗
PubMed1996

Pyuria among chronically incontinent but otherwise asymptomatic nursing home residents.

OBJECTIVE: To determine the prevalence of pyuria and its relationship to bacteriuria in a representative sample of chronically incontinent nursing home residents. DESIGN: Prospective, descriptive case series. SETTING: Six nursing homes. PARTICIPANTS: Two hundred fourteen chronically incontinent, but otherwise asymptomatic, nursing home residents who were enrolled in a clinical intervention trial for urinary incontinence. MEASURES: Two hundred fourteen urine specimens were collected by a validated clean catch technique. Each specimen underwent dipstick testing for leukocyte esterase, microscopic urinalysis to determine the number of white blood cells per high power field of centrifuged urine, and quantitative urine culture using standard laboratory techniques. RESULTS: The overall prevalence of pyuria was 45%, as defined by > 10 white blood cells per high field of spun urine, and the overall prevalence of bacteriuria was 43%, as defined by the growth of > 100,000 colony forming units of a urinary pathogen. Fifty-nine percent of the specimens with bacteriuria and 34% of the specimens without bacteriuria had pyuria. Of specimens with pyuria, 56% had bacteriuria, and of specimens without pyuria, 31% had bacteriuria. When any colon change on the leukocyte esterase pad was considered positive, this finding had a sensitivity of 83% and a specificity of 52% for pyuria on microscopic urinalysis. CONCLUSIONS: Pyuria is common among chronically incontinent nursing home residents, both in the presence and absence of bacteriuria. Clinicians must therefore be cautious in interpreting the presence of pyuria to indicate symptomatic infection in this population. Using pyuria to determine the need for antimicrobial treatment could result in unnecessary expense and morbidity as well as contribute to the development of resistant organisms in nursing homes. Research is needed to define pyuria better, to determine its prevalence and relationship to bacteriuria among nursing home residents with symptoms of acute urinary tract infection, and to elucidate the etiology and significance of sterile pyuria in this population.

Aged↗
PubMed1996

[Fulminant or sub-fulminant hepatocellular failure caused by metastatic invasiveness of the liver: an other cause of hypoxic hepatitis?].

OBJECTIVES: The purpose of this retrospective study was to report a series of 9 new cases of fulminant hepatic failure due to metastatic liver disease and to identify signs to support a theory of hypoxia. METHODS: In these 9 cases and in 38 previously published cases of fulminant or subfulminant liver failure, we looked for clinical (shock, sepsis, and cutaneous signs of circulatory failure), laboratory (marked increase in serum aminotransferases levels) and histological (cell necrosis) parameters compatible with liver hypoxia. RESULTS: Cutaneous signs of circulatory failure or shock were observed in 3 of the 9 cases in this study, and were not due to cardiogenic or septic shock. A marked increase in serum aminotransferases levels, 10 times above the upper limit of normal, was observed in 8 of the 9 cases in the present study and in 23 of 37 cases of the literature. Liver cell necrosis was observed in 6 of the 7 autopsied patients in this series and in 20 of 34 cases in the literature. Generally, liver cell necrosis was more severe than tumor cell necrosis and was related to the degree of sinusoidal involvement by tumoral cells. In one case, hepatic blood flow was decreased despite a high level of cardiac blood flow suggesting impairment of circulation in the liver. CONCLUSIONS: These 9 cases and a review of the literature support the hypothesis of hypoxic liver cell necrosis leading to acute liver failure in cases of metastatic liver disease. However, liver hypoxia cannot explain all the reported cases and was never due to circulatory failure from cardiac or septic causes, but to the sinusoidal involvement by tumor cells.

Adult↗
PubMed1995

Formation and properties of C1-inhibitor polymers.

Heating of the serpin C1-inhibitor above 55 degrees C induced the formation of inactive polymers. Western blotting of non-denaturing gels showed that the polymers bound to the conformation specific monoclonal antibody 4C3, suggesting that a similar conformational change to that occurring in complexed or cleaved inhibitor had taken place. N-Terminal analysis of tryptic peptides which bound to 4C3 showed that the epitope resides within residues 288-444, a region which includes parts of beta-sheets A and C. alpha 1-Antichymotrypsin, alpha 2-antiplasmin, angiotensinogen and thyroxine binding globulin also polymerised on heating, indicating that this is a property of many serpins.

Antibodies, Monoclonal↗
PubMed1995

The effect of sex and age on antithrombin biosynthesis in the rat.

Antithrombin is the primary inhibitor of Factor Xa and thrombin. Numerous reports have indicated that age and sex can influence antithrombin levels, but details of the regulation of antithrombin biosynthesis are not known. Thus, a characterization of antithrombin mRNA in eight tissues of young and old male and female rats was carried out. Liver produced the most mRNA, and hence contributes the majority of the plasma antithrombin, followed by the kidneys, with no age or sex related differences in mRNA levels being observed. Elevated amounts of mRNA were detected in aortas of old male rats compared to young ones. No antithrombin mRNA was detected in brain, lung, heart or skeletal muscle, and spleen showed low but variable levels. Plasma antithrombin protein was elevated in old female rats compared to young female or old male rats. These results show that the rat provides a potentially useful system to study the in vivo regulation of antithrombin biosynthesis.

Age Factors↗
PubMed1995

Does eradicating bacteriuria affect the severity of chronic urinary incontinence in nursing home residents?

OBJECTIVE: To determine the effects of eradicating otherwise asymptomatic bacteriuria on the severity of chronic urinary incontinence among nursing home residents. DESIGN: Residents were categorized as nonbacteriuric or bacteriuric on the basis of urine cultures. Bacteriuric residents were then randomly assigned to immediate and delayed treatment groups. The delayed treatment group was included to control for spontaneous changes in the severity of incontinence. The immediate treatment group received antimicrobial therapy for 7 days; after outcome measures had been repeated, the delayed treatment group was treated. SETTING: 6 community-based nursing homes. PATIENTS: Nursing home residents with chronic urinary incontinence. MEASUREMENTS: The frequency and volume of urinary incontinence were determined by physical checks for wetness by trained research aides hourly between 7 a.m. and 7 p.m. for 3 days in all patient groups (non-bacteriuric, bacteriuric with immediate treatment, and bacteriuric with delayed treatment) at baseline, after the immediate treatment group was treated, and again after the delayed treatment group was treated. RESULTS: 191 residents were enrolled, and 176 completed the study. Bacteriuria was eradicated by antimicrobial therapy in 71 residents (40%), and 17 residents (10%) had bacteriuria before and after therapy. The percentage of hourly checks at which the residents were found wet and other measures of incontinence severity remained essentially the same after bacteriuria was eradicated. In the nonbacteriuric group, the percentage of checks that were wet increased from 29% (95% CI, 26% to 32%) at baseline to 30% (CI, 27% to 34%) on repeated measurement. In the bacteriuric groups, the percentage increased from 34% (CI, 30% to 38%) before treatment to 35% (CI, 31% to 39%) after bacteriuria was eradicated. The presence of pyuria did not affect the results. CONCLUSION: Eradicating bacteriuria has no short-term effects on the severity of chronic urinary incontinence among nursing home residents. Our data support the practice of not treating asymptomatic bacteriuria in this population and validate the recommendations in the Health Care Financing Administration's Resident Assessment Protocol for urinary incontinence.

Aged↗
PubMed1995

[Should patients over 65 years old with acute myeloid leukemia be treated with myelosuppressive chemotherapy?].

Acute myeloid leukemia (AML) is frequently encountered in elderly patients (> 65) whereas most myelosuppressive chemotherapy protocols are restricted to younger patients. We retrospectively reviewed the 21 patients older than 65 (median age: 70, range: 66-86) hospitalized in our leukemia unit for recently diagnosed AML between 1. 1. 1988 and 31. 3. 1993. 16 had de novo AML (n-AML) and 5 had AML secondary to myelodysplastic syndromes (s-AML). Induction therapy consisted of cytarabine and either daunorubicine or mitoxantrone at conventional dosage in 18/21 patients. Early consolidation therapy was given to 14/21 patients and consisted of m-AMSA and VP-16 in 11 of them. The response to, and toxicity from, myelosuppressive chemotherapy was different according to the type of AML. In patients with n-AML a complete remission (CR) was obtained in 63% (10/16) and only 19% (3/16) died of MCT-related toxicity. In contrast, only 1/5 patients with s-AML achieved CR while 4/5 died of toxicity. The median duration of CR was 40 weeks (range: 5-147+) and median overall survival 23 weeks (range: 1-211+), with an estimated 3-year overall survival rate of 9.5% (2/21). Overall survival of patients with n-AML was significantly longer than that of patients with s-AML (p < 0.05). Hospital stay in relation to survival time was 100% for patients with s-AML, 49% for patients with n-AML not achieving CR and 25% for patients with n-AML with CR. In conclusion, elderly patients with AML can benefit from myelosuppressive chemotherapy providing they present with de novo AML.

Aged↗
PubMed1995

[Lipoprotein (a) in liver diseases. Correlation between low levels and liver function].

OBJECTIVES: To analyze the role of the liver function on the serum levels of lipoprotein(a) (Lp(a)), a lipoprotein considered to be a risk factor for atherosclerosis. METHODS: To measure the Lp(a) levels in patients with liver disease (n = 68) due to various causes and in patients with no liver disease and of similar age and sex-ratio (n = 62) and to analyze the relationship between Lp(a) levels on one hand and liver function and lipid and apoprotein levels on the other hand. RESULTS: Patients with liver disease had significantly lower levels of Lp(a). Lp(a) levels were significantly lower in patients with more severe liver disease (Child Turcotte classification) and significantly correlated with liver function tests, in particular those related to the microsomal function and the synthetic capacity of the liver (albumin, coagulation tests, apoprotein A-II). In patients with liver disease, mean Lp(a) levels were not significantly different between those with and those without chronic alcohol intake. CONCLUSIONS: Patients with liver disease have low levels of Lp(a) that are related to reduced synthetic capacity of this organ and are not linked to a specific cause of liver disease, in particular excess alcohol intake.

Adult↗
PubMed1995

Cleaved L-selectin concentrations in meningeal leukaemia.

Involvement of the central nervous system has important therapeutic implications in acute leukaemia. Because the identification of blast cells in cerebrospinal fluid (CSF) is often difficult, there is a need for sensitive markers of leukaemic infiltration. Since the shed form of L-selectin (sL-selectin) is frequently increased in acute leukaemia (sL-selectin+ leukaemia), we examined whether assay of sL-selectin in CSF could improve our ability to detect such meningeal involvement. CSF sL-selectin was significantly (p < 0.001) higher in 15 patients with sL-selectin+ meningeal leukaemia (median 60 ng/mL, range 34-150) than in 20 patients with acute leukaemia without meningeal involvement (12 ng/mL, 1-39) or 88 control patients (14 ng/mL, 0-37). Serial measurements of sL-selectin in patients with sL-selectin+ leukaemic meningitis showed increased CSF concentrations of the cleaved receptor in 4 patients with therapy-resistant meningeal leukaemia and sustained normal concentrations in 9 patients in remission. Our results suggest that CSF sL-selectin may be a useful marker in the detection of meningeal involvement by blast cells in patients with sL-selectin+ leukaemia.

Adult↗
PubMed1995

The effect of cleavage by a Crotalus atrox alpha-proteinase fraction on the properties of C1-inhibitor.

The effect of cleavage of C1-inhibitor at Pro36 by a Crotalus atrox alpha-proteinase fraction on the properties of this serpin was studied. This truncated C1-inhibitor (des 1-36) was fully active as an inhibitor of kallikrein, beta-factor XIIa, and C1s, and modulated the functions of C1 in a normal manner. Also, the half-life of the truncated protein in the circulation of rabbits, both alone and in complex with C1, was not altered. These results show that shock-like symptoms caused by C. atrox envenomation are not attributable to a deficiency in C1-inhibitor caused by the action of the metalloproteinase in the alpha-proteinase fraction.

Amino Acid Sequence↗