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S Bruno

Publications and source records attributed to S Bruno.

At least 19 recordsLinked to original sources
PubMed2006

The role of bright liver echo pattern on ultrasound B-mode examination in the diagnosis of liver steatosis.

AIM: The observation of bright liver echo pattern on ultrasound is commonly considered a sign of hepatic steatosis. However, the interference of liver fibrosis on sensitivity and specificity of bright liver echo pattern has caused many to question its effectiveness as a diagnostic tool. The objective of this study was to evaluate the sensitivity, specificity and predictive values of bright liver echo pattern for liver steatosis. PATIENTS AND METHODS: We studied 235 consecutive patients suspected of having liver disease of various aetiologies. Median age was 52 years (range, 17-72 years), and there was a male/female ratio of 1:18. All patients underwent ultrasound examination before liver biopsy and was performed by two operators. The presence or absence of bright liver echo pattern and posterior attenuation or areas with different patterns of fat infiltration were noted. Histologic evaluation was performed and graded by Ishak score. Steatosis was categorised as absent, 0-2%, 3-29% to 30-49% or >50%. RESULTS: Interobserver concordance was high. Bright liver echo pattern was found in 67% of patients with steatosis of any degree and 89% of patients with steatosis of >or=30%. Only three patients without steatosis, who had a low Ishak score, demonstrated bright liver echo pattern on ultrasonography. The sensitivity, specificity, positive predictive value and negative predictive value of bright liver echo pattern for steatosis were 64%, 97%, 96.0% and 65%, respectively. Among the subgroup of patients who had steatosis of >or=30%, the sensitivity, specificity, positive predictive value and negative predictive value of bright liver echo pattern were 91%, 93%, 89% and 94%, respectively. The sensitivity, specificity, positive predictive value and negative predictive value of posterior attenuation and/or skip areas associated with bright liver echo pattern for steatosis were 89.7%, 100%, 100% and 92.3%, respectively. Univariate analysis showed bright liver echo pattern to be associated only with steatosis and not with fibrosis. CONCLUSION: We concluded that the presence of bright liver echo pattern is a sign of liver steatosis and that liver fibrosis does not interfere with ultrasound measurements. Posterior attenuation and/or skip areas are closely related to steatosis of >or=30%.

Adolescent↗
PubMed2005

Cryoglobulinemia in kidney transplant recipients.

The aim of this study was to assess the presence of cryoglobulins, the constitution of the cryoprecipitate, as well as the possible etiology and clinical features in kidney transplant recipients. We excluded patients with clinical or laboratory evidence of autoimmune, liver or neoplasm disease, infections, blood transfusions or immunizations in the previous 3 months. Detection of cryoglobulins was obtained from the peripheral venous blood. In cases of cryoprecipitate formation it was analyzed using anti-IgG, anti-IgM, anti-IgA, anti-C3, and anti-C4 antibodies. The hepatitis C virus (HCV) was detected by the polymerase chain reaction. Thirty-nine patients were selected, of whom 23 were men and the overall mean age was 40.6 +/- 12.7 years. Cryoprecipitate was detected in 74.4% (29/39) patients. Among patients with or without cryoprecipitate formation, the serum creatinine values, the percentage of patients with proteinuria, and the posttransplantation times were similar. In patients with cryoglobulins, 37.9% (11/29) were HCV positive. The etiology was not determined for the other patients. The IgG, IgM, and IgA immunoglobulins and the complement fractions C3 and C4 were found in the cryoprecipitate. Their compositions were similar among patients with or without HCV. Few clinical features were associated with the presence of cryoglobulins, including deep venous thrombosis, cutaneous purpura and peripheral neuropathy. In conclusion, cryoglobulinemia was prevalent in kidney transplant recipients, but appeared to not affect graft function. HCV infection was the most frequently associated etiology and clinical features were infrequent.

Adult↗
PubMed2003

Safety and efficacy of laparoscopic radiofrequency ablation of hepatocellular carcinoma in patients with liver cirrhosis.

BACKGROUND: The optimal treatment for hepatocellular carcinoma (HCC) is surgical resection. However, only a small percentage of patients are operative candidates. Percutaneous radiofrequency interstitial thermal ablation (RITA) has been shown to be efficacious in the treatment of unresectable HCC. Recent advances in laparoscopic ultrasound have greatly improved the accuracy in detecting intrahepatic HCC nodules, many of which were missed by computed tomography. Our objective was to introduce a novel operative combination of laparoscopic ultrasound with laparoscopic RITA in the treatment of HCC. METHODS: Eighty-eight patients with HCC in liver cirrhosis were submitted to laparoscopic RITA under sonographic guide. Most patients were in Child's A class of liver function. Patients with large tumors (> 5 cm), portal vein thrombosis, or severe liver disease (Child's C class) were excluded. RESULTS: The laparoscopic RITA procedure was completed in 86 of 88 patients (98% feasibility rate). Laparoscopy with laparoscopic ultrasound identified 23 new malignant lesions (27%) in comparison with the results of preoperative imaging. A total of 127 lesions were treated by RITA. There was no operative mortality. Sixty-one patients had no complication (71%). After a mean follow-up of 14.3 +/- 11.6 months, a complete response with a 100% necrosis was achieved in 70 of 83 patients examined (86%). During follow-up, 9 patients (11%) locally recurred at the RITA site and 38 patients (46%) had new malignant nodules. CONCLUSIONS: Laparoscopic RITA of HCC proved to be a safe and effective technique in the short term. This technique may be indicated when the percutaneous approach to the lesion is very difficult or if the patient is too ill to undergo laparotomy.

Adult↗
PubMed2003

Expression of costimulatory molecules in human neuroblastoma. Evidence that CD40+ neuroblastoma cells undergo apoptosis following interaction with CD40L.

Tumour cells display low to absent expression of costimulatory molecules. Here, we have investigated the expression of costimulatory molecules (CD40, CD80, CD86, PD-1L, B7H2, OX40L and 4-1BBL) in human neuroblastoma (NB) cells, since virtually no information is available on this issue. Both established NB cell lines and primary tumours were tested by RT-PCR and flow cytometry. Neuroblastoma cell lines expressed the transcripts of all costimulatory molecule genes, but not the corresponding proteins. Culture of NB cell lines with human recombinant (r)IFN-gamma induced surface expression of CD40 in half of them. Primary NB cells showed CD40, CD80, CD86, OX40L, 4-1BBL, but not PD-1L and B7H2, mRNA expression. Surface CD40 was consistently detected on primary NB cells by flow cytometry. Interferon-gamma gene-transfected NB cells expressed constitutively surface CD40 and were induced into apoptosis by incubation with rCD40L through a caspase-8-dependent mechanism. CD40 may represent a novel therapeutic target in NB.

Antigens, Differentiation↗
PubMed2002

Role of different medium and growth factors on placental blood stem cell expansion: an in vitro and in vivo study.

Expansion of haemopoietic stem cells from placental blood has been obtained with a combination of flt3 ligand (FL), thrombopoietin (TPO), kit-ligand (KL) with or without interleukin-6 (IL6) in serum-replete medium. For clinical use, cell expansion in the absence of serum is a clear advantage. Therefore, stem cell expansion in serum-free (SF) medium with a combination of three (FL, TPO, KL) or four (FL, TPO, KL, IL6) growth factors was compared with the results obtained using fetal calf serum (FCS) or human serum (HS). Human CD34(+) placental blood cells were cultured in the presence of FL, TPO, KL +/- IL6 with SF medium, HS and FCS for up to 8 weeks. CD34(+), CFC, LTC-IC content was measured at intervals. To determine the in vivo repopulating capacity of expanded cells, CD34(+) expanded cells were transplanted in sublethally irradiated NOD/SCID mice. With the three growth factor combination the CD34(+) cell number increased steadily up to the 8 weeks of culture. CD34(+) cells were expanded 67.5-fold with SF, 11.7 with HS and 49.2 with FCS. However, when CFCs and LTC-ICs were considered, a continuous expansion was observed only with HS and FCS, whereas in SF medium after 6 weeks their number started to decline. The addition of IL-6 did not change the expansion significantly. Cells grown ex vivo for 14 days were transplanted into NOD/SCID mice. The engraftment of human cells in mice was higher for serum-replete than for SF expanded cells. Nevertheless, SF cultured cells were also able to engraft both marrow and spleen in all animals. In addition, engrafted human cells still maintained clonogenic ability. With KL, FL, TPO +/- IL6 it is possible to expand haemopoietic progenitor cells in a SF medium. Compared with serum-replete cultures, the absolute number of clonogenic cells and in vivo repopulating cells is lower. Although the degree of expansion remains significant, a clinical trial still needs to be carried out to address the question of whether this expansion might be useful in reducing post-transplant aplasia.

Animals↗
PubMed2002

Retreatment with interferon plus ribavirin of chronic hepatitis C non-responders to interferon monotherapy: a meta-analysis of individual patient data.

BACKGROUND AND AIMS: Retreatment with a combination of alpha interferon (IFN) plus ribavirin of patients with chronic hepatitis C who did not respond to IFN monotherapy has not been assessed in large controlled studies. METHODS: To assess the effectiveness and tolerability of IFN/ribavirin retreatment of non-responders to IFN and to identify predictors of complete (biochemical and virological) sustained response, we performed a meta-analysis of individual data on 581 patients from 10 centres. Retreatment with various IFN schedules (mean total dose 544 mega units) and a fixed ribavirin dose (1000-1200 mg/daily depending on body weight) was given for 24-60 (mean 39.5) weeks. RESULTS: Biochemical end of treatment and sustained responses were observed in 271/581 (46.6%; 95% confidence interval (CI) 42.6-50.7%) and in 109/581 (18.7%; 95% CI 15.6-22.0%) cases, respectively. Two hundred and six of 532 patients (38.7%; 95% CI 34.6-42.9%) had an end of treatment complete response to retreatment while a complete sustained response occurred in 88 of 559 (15.7%; 95% CI 12.8-18.8%). Fifty four of 581 patients (9.2%; 95% CI 7.0-11.7%) stopped retreatment due to adverse effects. By logistic regression, complete sustained response was predicted independently by age <45 years (p=0.04), by normal pretreatment gamma-glutamyltransferase levels (p=0.01), and by a second course total IFN dose of at least 432 mega units (p=0.008). CONCLUSIONS: The overall low probability of effectiveness argues against indiscriminate retreatment of all IFN monotherapy non-responders with IFN/ribavirin. Patients less than 45 years old with normal gamma-glutamyltransferase levels who were retreated with high dose long course combination therapy had a complete sustained response rate of 30%.

Adult↗
PubMed2001

Mutational effects at the subunit interfaces of human hemoglobin: evidence for a unique sensitivity of the T quaternary state to changes in the hinge region of the alpha 1 beta 2 interface.

A set of variant human hemoglobins, each with an Ala or Gly substitution at a single residue, has been prepared, and the kinetics of their reactions with carbon monoxide have been measured. This reaction is rate-limited by the binding of the first CO to the deoxygenated T state of the protein. The magnitudes of the effects of the mutations on CO combination vary widely, and, with the exception of beta Y145, the residues with the most significant effects on these kinetics are found in the hinge region of the alpha 1 beta 2 interface. Mixed-metal hybrids, with zinc protoporphyrin IX in place of heme on both alpha or both beta subunits, were prepared for beta W37E, beta W37A, alpha Y140G, and alpha Y140A, hinge region variants causing large kinetic changes, and for beta Y145G. Such hybrids permit measurements of the kinetics of CO binding to only the heme-containing alpha or beta subunits within the unliganded hemoglobin tetramer. Mutations at beta 37 and alpha 140 have global effects on the T state, increasing the rates of CO binding to both types of subunits. Mutation of beta Y145 has a large effect on the beta subunits in the deoxygenated T state, but very little effect on the alpha subunits. Oxygen equilibria measurements on the crystalline T state of beta W37E also indicate large affinity increases in both subunits of this variant. The overall oxygen equilibria of the variant hemoglobins in solution are sensitive to numerous variables besides the properties of the deoxygenated T state. In contrast to CO combination kinetics, the residues whose alterations cause the largest changes in overall oxygen equilibria in solution are scattered seemingly randomly within the alpha 1 beta 2 interface.

Amino Acid Substitution↗
PubMed2001

Functional properties of the active core of human cystathionine beta-synthase crystals.

Human cystathionine beta-synthase is a pyridoxal 5'-phosphate enzyme containing a heme binding domain and an S-adenosyl-l-methionine regulatory site. We have investigated by single crystal microspectrophotometry the functional properties of a mutant lacking the S-adenosylmethionine binding domain. Polarized absorption spectra indicate that oxidized and reduced hemes are reversibly formed. Exposure of the reduced form of enzyme crystals to carbon monoxide led to the complete release of the heme moiety. This process, which takes place reversibly and without apparent crystal damage, facilitates the preparation of a heme-free human enzyme. The heme-free enzyme crystals exhibited polarized absorption spectra typical of a pyridoxal 5'-phosphate-dependent protein. The exposure of these crystals to increasing concentrations of the natural substrate l-serine readily led to the formation of the key catalytic intermediate alpha-aminoacrylate. The dissociation constant of l-serine was found to be 6 mm, close to that determined in solution. The amount of the alpha-aminoacrylate Schiff base formed in the presence of l-serine was pH independent between 6 and 9. However, the rate of the disappearance of the alpha-aminoacrylate, likely forming pyruvate and ammonia, was found to increase at pH values higher than 8. Finally, in the presence of homocysteine the alpha-aminoacrylate-enzyme absorption band readily disappears with the concomitant formation of the absorption band of the internal aldimine, indicating that cystathionine beta-synthase crystals catalyze both beta-elimination and beta-replacement reactions. Taken together, these findings demonstrate that the heme moiety is not directly involved in the condensation reaction catalyzed by cystathionine beta-synthase.

Binding Sites↗
PubMed2001

Radiofrequency interstitial thermal ablation of hepatocellular carcinoma in liver cirrhosis. Role of the laparoscopic approach.

BACKGROUND: The laparoscopic approach to radiofrequency interstitial thermal ablation (RITA) of hepatocellular carcinoma (HCC) with intraoperative ultrasound guidance has been proposed with the aim of obtaining additional information for a better neoplastic staging and a complete and effective treatment of the liver lesions in patients with a difficult percutaneous approach. METHODS: In this pilot study, 29 patients with HCC in liver cirrhosis were submitted to laparoscopic RITA under sonographic guide. Most of these patients were in Child's A class of liver function. Patients with large tumors (> 5 cm), portal vein thrombosis, or severe liver disease (Child's C class) were excluded from the study. RESULTS: The laparoscopic RITA procedure was completed in 27 of 29 patients (93% feasibility rate). The laparoscopic ultrasound examination identified new malignant liver nodules in five patients (18.5%). A total of 44 lesions were treated. The mean operative time was 75.8 +/- 20.5 min (range, 45-120 min), and the mean RITA time was 18 +/- 10 min (range, 10-56 min). There was no operative mortality, and postoperative morbidity was low (four cases) without any mortality. A complete tumor necrosis was observed in 90% of the patients via spiral computed tomography (CT) 1 month after treatment. CONCLUSIONS: Laparoscopic RITA of hepatocellular carcinoma proved to be a safe and effective technique, at least in the short term. Its role in the treatment of HCC needs to be defined in larger series.

Aged↗
PubMed2001

Long-term beneficial effects in sustained responders to interferon-alfa therapy for chronic hepatitis C.

BACKGROUND/AIMS: Assessment of chronic hepatitis C outcome in sustained responders to interferon requires prolonged observation and close monitoring. We prospectively studied the impact of sustained response on histology and clinically relevant outcomes. METHODS: The 47 sustained responders (ten with cirrhosis) from two interferon trials involving 235 chronic hepatitis C patients (81 with cirrhosis) were included. Hepatitis C virus (HCV) RNA was assessed every 6 months, liver histological changes from baseline, 6-12 and 48-72 months after treatment discontinuation. RESULTS: The mean follow-up was 102 +/- 19 months. HCV RNA became undetectable in 36/47 responders. Four responders, who had remained viremic, later relapsed. The histology progressively improved in non-viremic and viremic patients, with a more marked improvement in the former (P = 0.0089), normalizing in 53 vs. 0% (P = 0.0220). No patient progressed to cirrhosis. One non-viremic cirrhotic patient developed a hepatocellular carcinoma. Non-responders from the two original trials had worse histological outcomes and those with cirrhosis had a higher rate of clinically relevant events compared with cirrhotics showing a sustained biochemical response (4.5 vs. 1.2 cases/100 person-years; CI for the difference, 0.3-6.3). CONCLUSIONS: Most sustained, virological responders without cirrhosis normalize liver histology in the long-term and are cured of the disease. Sustained responders remaining viremic still show histological improvement, albeit to a lesser extent.

Adult↗
PubMed2001

Interaction between novel anticancer agents and radiation in non-small cell lung cancer cell lines.

Integration of chemotherapy and radiation is the standard practice in the management of locally advanced inoperable NSCLC. To assess the biological interaction between third generation chemotherapeutic agents and radiation in non-small cell lung cancer (NSCLC) in vitro, we tested a number of different drugs (paclitaxel, docetaxel, gemcitabine, topotecan, SN-38 and cisplatin) combined with radiation, in lung cancer cell lines. Cellular chemosensitivity was determined, using the semi-automated colorimetric MTT assay, after 48, 72 and 96 h of exposure to increasing drug concentrations, (0.001-100 microM) and radiation doses (100-400 cGy). Cell lines used were the adenocarcinoma (ADK), A-549, and the squamous-cell carcinoma (SCC), LX-1. Cells were pre-treated with anticancer agents at 24, 12 and 0 h before irradiation. Cytofluorimetric cell cycle analysis was performed. A significant S-phase block or a G(2)/M block was seen with gemcitabine and topotecan or paclitaxel pre-treatment, respectively. Apoptosis was seen only after paclitaxel exposure in the A-549 cell line. Despite a similar pattern of cell-kinetic changes induced by chemotherapy pre-treatment in all cell lines, the adenocarcinoma A-549 cell line was not radiosensitized by any of the anticancer agents tested, whereas synergism was observed in the LX-1 squamous carcinoma cell line, when exposed to gemcitabine, SN-38, topotecan and cisplatin. Paclitaxel, despite a favourable cell cycle effect, was not found to be synergistic with radiotherapy in our experimental model. In conclusion, the observed synergism appears to be dose- and timing-independent and seems to be related to the histological subtype being present in SCC only. Favourable perturbation of the cell cycle is evident with all the new agents tested in both cell types, but was not sufficient to produce synergism with radiation.

Antineoplastic Agents↗
PubMed2001

Post-transplant renal artery stenosis: the hemodynamic response to revascularization.

BACKGROUND: Percutaneous transluminal angioplasty and stenting are relatively noninvasive approaches to treat post-transplant renal artery stenosis. However, the real impact of this procedure on renal function recovery has never been quantitated precisely to date. METHODS: In eight consecutive renal transplant patients with renal graft artery stenosis, blood pressure, body weight, and anatomical, functional, and Doppler ultrasound parameters were evaluated before and one month after renal artery transluminal angioplasty and stenting. On both occasions, glomerular filtration rate and renal plasma flow were evaluated by inulin and paraaminohippuric acid renal clearances, and glomerular size-selective function was evaluated by the fractional clearances of neutral dextran macromolecules. RESULTS: The correction of renal artery stenosis, by normalizing renal vascular resistances, fully restored kidney perfusion and decreased arterial blood pressure, relieved water and sodium retention, restored an almost laminar arterial blood flow, and normalized vascular shear stress without appreciable effects on glomerular barrier size-selective function and proteinuria. Preangioplasty and postangioplasty renal resistive indices and peak systolic blood velocity estimated by Doppler ultrasounds were significantly correlated with the effective renal plasma flow and the blood velocity calculated at the site of stenosis. All patients were discharged without sequelae one or two days after angioplasty. CONCLUSIONS: Percutaneous transluminal angioplasty and stenting are safe and effective procedures to normalize the functional changes sustained by hemodynamically significant artery stenosis after renal transplantation. Doppler ultrasound scanning is a reliable and reproducible technique to monitor the renal functional response to vascular reperfusion.

Adult↗
PubMed2001

Site-directed mutations of human hemoglobin at residue 35beta: a residue at the intersection of the alpha1beta1, alpha1beta2, and alpha1alpha2 interfaces.

Because Tyr35beta is located at the convergence of the alpha1beta1, alpha1beta2, and alpha1alpha2 interfaces in deoxyhemoglobin, it can be argued that mutations at this position may result in large changes in the functional properties of hemoglobin. However, only small mutation-induced changes in functional and structural properties are found for the recombinant hemoglobins betaY35F and betaY35A. Oxygen equilibrium-binding studies in solution, which measure the overall oxygen affinity (the p50) and the overall cooperativity (the Hill coefficient) of a hemoglobin solution, show that removing the phenolic hydroxyl group of Tyr35beta results in small decreases in oxygen affinity and cooperativity. In contrast, removing the entire phenolic ring results in a fourfold increase in oxygen affinity and no significant change in cooperativity. The kinetics of carbon monoxide (CO) combination in solution and the oxygen-binding properties of these variants in deoxy crystals, which measure the oxygen affinity and cooperativity of just the T quaternary structure, show that the ligand affinity of the T quaternary structure decreases in betaY35F and increases in betaY35A. The kinetics of CO rebinding following flash photolysis, which provides a measure of the dissociation of the liganded hemoglobin tetramer, indicates that the stability of the liganded hemoglobin tetramer is not altered in betaY35F or betaY35A. X-ray crystal structures of deoxy betaY35F and betaY35A are highly isomorphous with the structure of wild-type deoxyhemoglobin. The betaY35F mutation repositions the carboxyl group of Asp126alpha1 so that it may form a more favorable interaction with the guanidinium group of Arg141alpha2. The betaY35A mutation results in increased mobility of the Arg141alpha side chain, implying that the interactions between Asp126alpha1 and Arg141alpha2 are weakened. Therefore, the changes in the functional properties of these 35beta mutants appear to correlate with subtle structural differences at the C terminus of the alpha-subunit.

Amino Acid Substitution↗
PubMed2001

High and low oxygen affinity conformations of T state hemoglobin.

To understand the interplay between tertiary and quaternary transitions associated with hemoglobin function and regulation, oxygen binding curves were obtained for hemoglobin A fixed in the T quaternary state by encapsulation in wet porous silica gels. At pH 7.0 and 15 degrees C, the oxygen pressure at half saturation (p50) was measured to be 12.4 +/- 0.2 and 139 +/- 4 torr for hemoglobin gels prepared in the absence and presence of the strong allosteric effectors inositol hexaphosphate and bezafibrate, respectively. Both values are in excellent agreement with those found for the binding of the first oxygen to hemoglobin in solution under similar experimental conditions. The corresponding Hill coefficients of hemoglobin gels were 0.94 +/- 0.02 and 0.93 +/- 0.03, indicating, in the frame of the Monod, Wyman, and Changeux model, that high and low oxygen-affinity tertiary T-state conformations have been isolated in a pure form. The values, slightly lower than unity, reflect the different oxygen affinity of alpha- and beta-hemes. Significantly, hemoglobin encapsulated in the presence of the weak effector phosphate led to gels that show intermediate oxygen affinity and Hill coefficients of 0.7 to 0.8. The heterogeneous oxygen binding results from the presence of a mixture of the high and low oxygen-affinity T states. The Bohr effect was measured for hemoglobin gels containing the pure conformations and found to be more pronounced for the high-affinity T state and almost absent for the low-affinity T state. These findings indicate that the functional properties of the T quaternary state result from the contribution of two distinct, interconverting conformations, characterized by a 10-fold difference in oxygen affinity and a different extent of tertiary Bohr effect. The very small degree of T-state cooperativity observed in solution and in the crystalline state might arise from a ligand-induced perturbation of the distribution between the high- and low-affinity T-state conformations.

Allosteric Site↗
PubMed2001

CD85/LIR-1/ILT2 and CD152 (cytotoxic T lymphocyte antigen 4) inhibitory molecules down-regulate the cytolytic activity of human CD4+ T-cell clones specific for Mycobacterium tuberculosis.

Antigen-specific cytolytic CD4+ T lymphocytes control Mycobacterium tuberculosis infection by secreting cytokines and by killing macrophages that have phagocytosed the pathogen. However, lysis of the latter cells promotes microbial dissemination, and other macrophages engulf the released bacteria. Subsequently, CD4+ T-cell-mediated killing of macrophages goes on, and this persistent process may hamper control of infection, unless regulatory mechanisms maintain a subtle balance between lysis of macrophages by cytolytic CD4+ cells and activation of cytolytic CD4+ cells by infected macrophages. We asked whether inhibitory molecules expressed by CD4+ cytolytic T lymphocytes could play a role in such a balance. To this end, human CD4+ T-cell clones specific for M. tuberculosis were produced that displayed an autologous major histocompatibility complex class II-restricted lytic ability against purified protein derivative (PPD)-pulsed antigen-presenting cells. All T-cell clones expressed CD152 (cytotoxic T-lymphocyte antigen 4 [CTLA-4]) and CD85/leukocyte immunoglobulin-like receptor 1 (LIR-1)/immunoglobulin-like transcript 2 (ILT2) inhibitory receptors, but not CD94 and the killer inhibitory receptor (or killer immunoglobulin-like receptor [KIR]) p58.2. CD3-mediated activation of the clones was inhibited in a redirected killing assay in which CD152 and CD85/LIR-1/ILT2 were cross-linked. Specific antigen-mediated proliferation of the clones was also sharply reduced when CD152 and CD85/LIR-1/ILT2 were cross-linked by specific monoclonal antibody (MAb) followed by goat anti-mouse antiserum. In contrast, blockade of the receptors by specific MAb only increased their proliferation. Production of interleukin 2 (IL-2) and gamma interferon (IFN-gamma) by the T-cell clones was also strongly reduced when CD152 and CD85/LIR-1/ILT2 were cross-linked. The lytic activity of the T-cell clones against PPD-pulsed autologous monocytes or Epstein-Barr virus-activated B cells was increased by blockade and decreased by cross-linking of the receptors. These results indicate that CD152 and CD85/LIR-1/ILT2 play a role in the regulation of the antigen-specific activity of CD4+ cytolytic T lymphocytes against PPD-presenting cells.

Abatacept↗
PubMed2001

Oxygen binding by single red blood cells from the red-eared turtle Trachemys scripta.

Oxygen-binding properties of single red blood cells from the red-eared turtle Trachemys scripta were measured by microspectrophotometry to describe the variation in oxygen affinity of red blood cells and to gain insight into the distribution of functionally different hemoglobins among red blood cells. Methodologically, this study represents the first report on the cell-to-cell variation in oxygen-binding properties based on oxygen-binding curves of single vertebrate red blood cells. The cells differed significantly with respect to oxygen affinity. Mean oxygen pressure at half saturation of the cells in a blood sample was found to be 20.1 +/- 3.3 (SD) Torr. The distribution of oxygen affinities among red blood cells is unimodal, indicating that the two hemoglobins found in turtle blood are not segregated in distinct cells. Therefore, the functional interaction shown by these hemoglobins in vitro is likely to take place in vivo. The considerable variation in oxygen affinity between individual red blood cells calls for its incorporation in models of tissue oxygenation.

Adenosine Triphosphate↗
PubMed2001

Functional characterization of heme proteins encapsulated in wet nanoporous silica gels.

Myoglobin and hemoglobin were encapsulated in wet, nanoporous silica gels. A rigorous evaluation of the effect of the encapsulation on protein dynamics and function was carried out by measuring the kinetics of carbon monoxide rebinding after nanosecond laser flash-photolysis with transient absorption detection, and the oxygen affinity with absorption microspectrophotometry. The time course of carbon monoxide binding to myoglobin evidenced a strongly enhanced geminate recombination and a faster bimolecular rebinding with respect to solution, whereas T and R quaternary states of hemoglobin exhibited a geminate phase and a bimolecular binding rate very similar to those observed in solution. Oxygen affinity of T-state hemoglobin was found to be close to that observed for the binding of the first oxygen to T-state hemoglobin in solution. Results indicate that some conformational transitions are kinetically restricted, allowing to isolate distinct tertiary and quaternary states. This opens the way to their detailed functional characterization and application to biodevices.

Absorption↗