Biomedical subjects

S Bernard

Publications and source records attributed to S Bernard.

At least 55 records · Page 3Linked to original sources

PubMed1998

Isolation and characterization of an evolutionary precursor of human monoamine oxidases A and B.

An interesting flavoprotein-type monoamine oxidase (MAO) was recently isolated from Aspergillus niger and cloned [Schilling, B. & Lerch, K. (1995a) Biochim. Biophys. Acta 1243, 529-537; Schilling, B. & Lerch, K. (1995b) Mol. Gen. Genet. 247, 430-438]. The properties of this MAO, as well as a substantial part of its amino acid sequence, resemble those of both MAO A and B from higher animals, raising the possibility that it may be an evolutionary precursor of these mitochondrial enzymes. It differs from MAO A and B in several respects, however, including the fact that it is soluble and of peroxisomal location and that the FAD is non-covalently attached. We have overexpressed the fungal enzyme (MAO-N) in Escherichia coli and isolated it in pure form. Since several of the observations of previous workers on MAO-N could not be reproduced, we have reexamined its substrate specificity, interaction with reversible and irreversible inhibitors and other catalytic and molecular properties. MAO-N has a considerably higher turnover number on many aliphatic and aromatic amines than either form of the mammalian enzyme. Some aspects of the substrate specificity resemble those of MAO B, while others are similar to MAO A, including biphasic kinetics in double reciprocal plots. Contrary to a previous report [Schilling, B. & Lerch, K. (1995a) Biochim. Biophys. Acta 1243, 529-537], however, the fungal enzyme does not oxidize serotonin, norepinephrine, dopamine or other biogenic amines. MAO-N is irreversibly inhibited by stoichiometric amounts of both (-)deprenyl and clorgyline in a mechanism-based reaction, forming flavocyanine adducts with N5 of the FAD, like the mammalian enzymes, but inactivation is much faster with clorgyline than deprenyl, suggesting a closer resemblance to MAO A than B. The dissociation constants for a large number of reversible competitive inhibitors have been determined for MAO-N and comparison with similar values for MAO A and B again pointed to a greater similarity to the former than the latter.

Amino Acid Sequence↗

PubMed1998

Increased sensitivity of E. coli to novobiocin, EDTA and the anticalmodulin drug W7 following overproduction of DjlA requires a functional transmembrane domain.

In earlier studies we found that E. coli is sensitive to anticalmodulin drugs such as W7. Mutants that are resistant to this drug were isolated, including wseA1. In an attempt to clone the wseA gene, we isolated a clone that restored sensitivity to the drug in the mutant. We found that this clone in fact suppresses W7 resistance through expression of djlA, which encodes a novel DnaJ-like protein. It was found previously that overproduction of DjlA could induce capsule synthesis via activation of the two-component regulatory pathway RcsC/B. In addition to suppression of wseA1, djlA overexpression increases the sensitivity of cells to EDTA and novobiocin, but not to other drugs tested. Although overexpression of a form of the protein carrying a mutation in, or lacking, the J-region of DjlA also led to increased sensitivity, indicating that the chaperone activity of this protein was not strictly required. the full-length, wild-type protein had a more pronounced effect. In contrast, a point mutation which affects the function of the transmembrane domain but not the localisation or stability of DjlA abolished the effects of DjlA overproduction.

Amino Acid Sequence↗

PubMed1998

Lack of association between carotid intima-media thickness and paraoxonase gene polymorphism in non-insulin dependent diabetes mellitus.

Paraoxonase (PON) is an HDL-bound enzyme capable of hydrolyzing lipid peroxides and believed to be in part responsible for the protective effect of HDL against LDL oxidation. Its activity is mainly determined by a gene polymorphism of the PON 1 gene (Glu-Arg 192). Low activity has been related to an elevated incidence of myocardial infarction. In several case-control studies, however, the high activity B allele is paradoxically more prevalent in patients. We have re-investigated this relationship, using carotid intima-media thickness (IMT) as a surrogate continuous variable for macroangiopathy. Genotypes were determined in 197 non insulin-dependent diabetic patients (HbAlc 8.8+/-0.15%, BMI 28.3+/-0.36). IMT, measured by high resolution mode B ultrasound, was the same for all genotypes (AA: 0.83+/-.013, AB 0.82+/-.017 and BB: 0.81+/-.034 mm). Bearers of the B allele displayed higher Lp(a) concentration (AA: 197+/-28, AB: 221+/-26, BB: 225+/-45 mg/l, P=0.024) with a significant linear trend (P < 0.005). Multiple regression showed age and systolic blood pressure, but not Lp(a), to be the main determinants of IMT variability without the contribution of the PON genotype. No consistent differences could be found between genotypes in the peroxidizability of LDL (lag-time, rate of diene production and maximal concentration). Our data support the view that there is no association between the early changes of atherosclerosis as defined by carotid IMT and variation in codon 192 of PON 1.

Age Factors↗

PubMed1998

Dysregulation of monocyte differentiation in asthmatic subjects is reversed by IL-10.

BACKGROUND: IL-10 can modulate the differentiation of normal monocytes to macrophages, increasing the proportion of maturing cells with a phenotype consistent with T cell suppressive activity. Analysis of the immunopathology in endobronchial biopsies from asthmatic subjects has revealed significantly reduced proportions of suppressive macrophage populations associated with chronic T-cell mediated inflammation. OBJECTIVE: This study investigates whether the altered homeostasis within the lung macrophage populations in asthma is reflected in aberrant differentiation of peripheral blood monocytes and whether this differentiation may be influenced by IL-10. METHODS: Monocytes from 14 normal individuals and 14 atopic asthmatics were grown in culture for 7 days in the presence or absence of IL-10, added on day 5. Double immunofluoresence studies were performed on cytospins of the differentiated macrophages using the monoclonal antibodies RFD1 and RFD7 to distinguish inductive and suppressive macrophages by their respective phenotypes. HLADR expression was quantified using the monoclonal antibody RFDR1. Macrophage function was determined by quantifying allostimulation in a mixed leucocyte reaction and by measuring TNFalpha and TGFbeta production. RESULTS: With no cytokine addition the proportion of maturing macrophages with a suppressive phenotype (D1+D7+) at day 7 was lower in the asthmatic samples (18%) compared with normals (25%). IL-10 increased the proportion of suppressive cells in cultures of both asthmatic and normal monocytes with the increase in the asthmatic subjects (94% increase) being significantly greater than that in normal subjects (32% increase) (P<0.01). Asthmatic monocytes had a greater effect in stimulating MLR than normals (P < 0.05) but the addition of IL-10 reduced T cell proliferation in an MLR to a equivalent level in both groups. CONCLUSIONS: These results suggest that a fundamental problem may exist in the differentiation of monocytes in asthma which may be reversed by IL-10.

Adolescent↗

PubMed1998

Emergency admissions of older people to hospital: a link with material deprivation.

BACKGROUND: The aim was to investigate whether variations in emergency admission to hospital amongst older people in Leicestershire vary with the level of material deprivation of the area in which they live. METHODS: Data were extracted from the Trent Patient Information System for patients aged 65 and over, admitted as an emergency medical admission to Leicestershire's acute and community hospitals on at least one occasion during the period October 1993-September 1994. The 1991 Census was used to examine the nature of the areas from which these emergency admissions were drawn and variations in emergency admission rates across Leicestershire. The relationship between emergency medical admissions and age, sex and material deprivation as measured by the Townsend deprivation score was examined. RESULTS: There were 13,305 people aged 65 or over with at least one emergency medical admission out of an estimated population (65 and over) in 1994 of 134,608 (9.9 per cent). Unconditional logistic regression showed that the risk of emergency admission increased with age and was also higher for men than for women. Emergency admissions increased significantly with increasing deprivation for each age group. This was most notable in the 65-74 years age group, yielding an odds ratio of 2.06 [95 per cent confidence interval (1.86, 2.29)], when comparing those from the most deprived areas with those from the least deprived areas. CONCLUSIONS: The increased risk of emergency medical admission to hospital, which is associated with residence in areas characterized as deprived by Census-based indicators, suggests there are enduring inequalities in health or health care amongst older people. Inequalities noted for all ages persist into old age, although in the 'oldest' age groups, the effect is weaker. Material deprivation may also be a proxy for other factors, such as differences in social support and the type of care received.

Aged↗

PubMed1998

Phase I trial of a 96 h paclitaxel infusion with filgrastim support in refractory solid tumor patients.

A phase I study of a 96 h paclitaxel infusion with filgrastim support was performed to determine the toxicity, maximum-tolerated dose (MTD) and pharmacokinetics in patients with refractory solid tumors. In this phase I trial, the initial paclitaxel dose was 140 mg/m2/96 h followed by filgrastim (5 microg/kg/day s.c.) beginning 24 h after the paclitaxel and continued until granulocyte recovery. Cycles were repeated every 21 days. Patients with refractory solid tumors were eligible; however, only one previous chemotherapy regimen was allowed. The dose of paclitaxel was escalated by 20 mg/m2/96 h in subsequent cohorts until dose-limiting toxicity (DLT) occurred. Pharmacokinetic analysis was performed by quantitating paclitaxel concentrations at baseline, 24, 48, 72 and 96 h after the start of the paclitaxel infusion. Twenty-one patients were entered into this trial of which 19 were evaluable. A total of 52 treatment cycles were administered. DLT was seen in two of four patients at 200 mg/m2/96 h, and consisted of diarrhea, mucositis and granulocytopenic infection. The MTD of the 96 h paclitaxel infusion was 180 mg/m2 with filgrastim support. Mucosal and granulocyte toxicity were correlated with steady-state paclitaxel concentrations (Css) greater than 0.100 micromol/l. In the presence of liver function test 1.5 times or lower than normal, metastatic liver disease did not alter paclitaxel Css. Objective responses were observed in non-small cell lung cancer, small cell lung cancer and melanoma. The recommended phase II dose of paclitaxel infused over 96 h with filgrastim support is 180 mg/m2. Paclitaxel Css correlate with mucosal and granulocyte toxicity. In the presence of normal enzymatic function, metastatic liver disease does not affect paclitaxel clearance.

Adult↗

PubMed1998

Histochemical and morphological characteristics of the vastus lateralis muscle in patients with chronic obstructive pulmonary disease.

PURPOSE AND METHODS: In this study, we examined the fiber-type proportions, cross-sectional areas (CSA), and capillarization from needle biopsies of the vastus lateralis muscle in 20 patients with chronic obstructive pulmonary disease (COPD) (FEV1 = 37 +/- 11% predicted, peak VO2 = 13 +/- 4 mL.min-1.kg-1) and nine age-matched normal subjects (peak VO2 = 33 +/- 7 mL.min-1.kg-1). The effects of endurance training on these parameters were also evaluated in 11 of the 20 patients with COPD. RESULTS: The proportion of Type I fiber was smaller in COPD than normals (34 +/- 14% vs 58 +/- 16 in normals, P < 0.0005) with a corresponding increase in Type IIb fiber (P = 0.015). The CSA of Type I, IIa, and IIab fibers was also smaller in COPD. The capillary to fiber ratio tended to be reduced in patients, but this difference did not reach statistical significance (P = 0.15). The number of capillary contact for Type I, IIa, and IIab fibers was significantly reduced in COPD compared with normal subjects (P < 0.05). When corrected for the CSA, this parameter was similar for both groups. After training, peak VO2 increased by 11% (P < 0.05), the fiber-type proportion remained unchanged, and the CSA of Type I and IIa fibers increased by 31 and 21%, respectively (P < 0.05). Although the number of capillary contact for each fiber types increased with training, the capillary to fiber ratio and the number of capillary contact for the different fiber types relative to their CSA remain unchanged. CONCLUSIONS: We conclude that in COPD, 1) the vastus lateralis muscle is characterized by a marked decrease in Type I fiber proportion, an increase in Type IIb fiber proportion, a decrease in Type I, IIa, and IIab fiber CSA and by a relatively preserved capillarization; and 2) a 12-wk training program induces a significant increase in Type I and IIa CSA.

Aged↗

PubMed1998

Pulmonary blood flow redistribution by increased gravitational force.

This study was undertaken to assess the influence of gravity on the distribution of pulmonary blood flow (PBF) using increased inertial force as a perturbation. PBF was studied in unanesthetized swine exposed to -Gx (dorsal-to-ventral direction, prone position), where G is the magnitude of the force of gravity at the surface of the Earth, on the Armstrong Laboratory Centrifuge at Brooks Air Force Base. PBF was measured using 15-micron fluorescent microspheres, a method with markedly enhanced spatial resolution. Each animal was exposed randomly to -1, -2, and -3 Gx. Pulmonary vascular pressures, cardiac output, heart rate, arterial blood gases, and PBF distribution were measured at each G level. Heterogeneity of PBF distribution as measured by the coefficient of variation of PBF distribution increased from 0.38 +/- 0.05 to 0.55 +/- 0.11 to 0.72 +/- 0.16 at -1, -2, and -3 Gx, respectively. At -1 Gx, PBF was greatest in the ventral and cranial and lowest in the dorsal and caudal regions of the lung. With increased -Gx, this gradient was augmented in both directions. Extrapolation of these values to 0 G predicts a slight dorsal (nondependent) region dominance of PBF and a coefficient of variation of 0.22 in microgravity. Analysis of variance revealed that a fixed component (vascular structure) accounted for 81% and nonstructure components (including gravity) accounted for the remaining 19% of the PBF variance across the entire experiment (all 3 gravitational levels). The results are inconsistent with the predictions of the zone model.

Acceleration↗

PubMed1998

Metabolic and hemodynamic responses of lower limb during exercise in patients with COPD.

Premature lactic acidosis during exercise in patients with chronic obstructive pulmonary disease (COPD) may play a role in exercise intolerance. In this study, we evaluated whether the early exercise-induced lactic acidosis in these individuals can be explained by changes in peripheral O2 delivery (O2). Measurements of leg blood flow by thermodilution and of arterial and femoral venous blood gases, pH, and lactate were obtained during a standard incremental exercise test to capacity in eight patients with severe COPD and in eight age-matched controls. No significant difference was found between the two groups in leg blood flow at rest or during exercise at the same power outputs. Blood lactate concentrations and lactate release from the lower limb were greater in COPD patients at all submaximal exercise levels (all P < 0.05). Leg D02 at a given power output was not significantly different between the two groups, and no significant correlation was found between this parameter and blood lactate concentrations. COPD patients had lower arterial and venous pH at submaximal exercise, and there was a significant positive correlation between venous pH at 40 W and the peak O2 uptake (r = 0.91, P < 0.0001). The correlation between venous pH and peak O2 uptake suggests that early muscle acidosis may be involved in early exercise termination in COPD patients. The early lactate release from the lower limb during exercise could not be accounted for by changes in peripheral O2. The present results point to skeletal muscle dysfunction as being responsible for the early onset of lactic acidosis in COPD.

Acidosis, Lactic↗

PubMed1998

Peripheral muscle weakness in patients with chronic obstructive pulmonary disease.

Peripheral muscle weakness is commonly found in patients with chronic obstructive pulmonary disease (COPD) and may play a role in reducing exercise capacity. The purposes of this study were to evaluate, in patients with COPD: (1) the relationship between muscle strength and cross-sectional area (CSA), (2) the distribution of peripheral muscle weakness, and (3) the relationship between muscle strength and the severity of lung disease. Thirty-four patients with COPD and 16 normal subjects of similar age and body mass index were evaluated. Compared with normal subjects, the strength of three muscle groups (p < 0.05) and the right thigh muscle CSA, evaluated by computed tomography (83.4 +/- 16.4 versus 109.6 +/- 15.6 cm2, p < 0.0001), were reduced in COPD. The quadriceps strength/thigh muscle CSA ratio was similar for the two groups. The reduction in quadriceps strength was proportionally greater than that of the shoulder girdle muscles (p < 0.05). Similar observations were made whether or not patients had been exposed to systemic corticosteroids in the 6-mo period preceding the study, although there was a tendency for the quadriceps strength/thigh muscle CSA ratio to be lower in patients who had received corticosteroids. In COPD, quadriceps strength and muscle CSA correlated positively with the FEV1 expressed in percentage of predicted value (r = 0.55 and r = 0. 66, respectively, p < 0.0005). In summary, the strength/muscle cross-sectional area ratio was not different between the two groups, suggesting that weakness in COPD is due to muscle atrophy. In COPD, the distribution of peripheral muscle weakness and the correlation between quadriceps strength and the degree of airflow obstruction suggests that chronic inactivity and muscle deconditioning are important factors in the loss in muscle mass and strength.

Aged↗

PubMed1998

Phase I and pharmacologic study of continuous infusion topotecan in combination with cisplatin in patients with advanced cancer: a Cancer and LeukemiaGroup B study.

PURPOSE: Preclinical and clinical data suggest that topotecan may be more effective, and perhaps less toxic, when administered as a continuous intravenous infusion (CIVI). A previous Cancer and Leukemia Group B (CALGB) trial of topotecan, given on a daily bolus schedule in combination with cisplatin, produced more hematologic toxicity than expected with either drug alone. Therefore, we designed this phase I trial to define the dose-limiting toxicities (DLTs) and the recommended phase II doses of cisplatin in combination with topotecan administered as a CIVI. Population pharmacodynamic models for the combination also were investigated. PATIENTS AND METHODS: Patients with advanced solid tumors and a maximum of one prior chemotherapy regimen for metastatic disease were eligible if they had a performance status of 0 to 1 and adequate renal, hepatic, and bone marrow function. Prior treatment with camptothecins or platinum compounds and prior pelvic irradiation were not allowed. The initial schedule consisted of a fixed dose of topotecan 0.4 mg/m2/d administered as a CIVI for 21 days and escalating doses of cisplatin administered on days 1, 8, and 15 of a 28-day schedule, until the maximum tolerated dose (MTD) was achieved. After severe hematologic toxicity was observed in the first two patients, the topotecan infusion was shortened to 14 days, and the total dose of cisplatin was administered on day 1 in all subsequent patients. After the MTD was defined, that cohort was expanded to include a total of 12 assessable patients. Hematopoietic growth factors were not allowed. For the pharmacologic studies, total topotecan plasma concentrations were measured by high-pressure liquid chromatography (HPLC) during infusion on days 3, 8, and 11 on the first cycle, and the median steady-state concentration (Tss) was determined. Platinum plasma concentrations on day 3 were measured by atomic absorption spectrometry. RESULTS: Of the 32 patients enrolled, 28 were assessable for toxicity and 24 for response. The primary toxicity was hematologic, with both neutropenia and thrombocytopenia being dose-limiting. The MTD of cisplatin was 75 mg/m2 on day 1 in combination with topotecan 0.4 mg/m2/d for 14 days. At this dose level, three of a total of 12 assessable patients had DLT. The pharmacodynamic relationship between Tss and the absolute neutrophil count at the nadir (ANCn) was described by the following equation: log10 (ANCn)=4.23 - 0.47 x Tss - 0.01 x cisplatin dose (P < .0001; R2=0.64). The substitution of platinum concentration for cisplatin dose in this model did not result in a significant improvement. Three patients had a partial response: one with duodenal carcinoma; a second with small-cell lung cancer; and a third with melanoma. CONCLUSION: Cisplatin can be given safely in combination with CIVI topotecan. However, toxicity was still substantial. Based on the current results and our previous trial of this combination, we conclude that, when combined with cisplatin, CIVI topotecan does not seem to be advantageous compared with the more traditional daily bolus schedule.

Adult↗

PubMed1998

Phase I study to determine the maximum-tolerated dose of radiation in standard daily and hyperfractionated-accelerated twice-daily radiation schedules with concurrent chemotherapy for limited-stage small-cell lung cancer.

PURPOSE: An improvement in radiation dose schedule is necessary to increase local tumor control and survival in limited-stage small-cell lung cancer. The goal of this study was to determine the maximum-tolerated dose (MTD) of radiation (RT) in both standard daily and hyperfractionated-accelerated (HA) twice-daily RT schedules in concurrent chemoradiation. METHODS: The study design consisted of a sequential dose escalation in both daily and HA twice-daily RT regimens. RT dose to the initial volume was kept at 40 to 40.5 Gy, while it was gradually increased to the boost volume by adding a 7% to 11 % increment of total dose to subsequent cohorts. The MTD was defined as the radiation dose level at one cohort below that which resulted in more than 33% of patients experiencing grade > or = 4 acute esophagitis and/or grade > or = 3 pulmonary toxicity. The study plan included nine cohorts, five on HA twice-daily and four on daily regimens for the dose escalation. Chemotherapy consisted of three cycles of cisplatin 33 mg/m2/d on days 1 to 3 over 30 minutes, cyclophosphamide 500 mg/m2 on day 1 intravenously (IV) over 1 hour, and etoposide 80 mg/m2/d on days 1 to 3 over 1 hour every 3 weeks (PCE) and two cycles of PE. RT was started at the initiation of the fourth cycle of chemotherapy. RESULTS: Fifty patients were enrolled onto the study. The median age was 60 years (range, 38-79), sex ratio 2.3:1 for male to female, weight loss less than 5% in 73%, and performance score 0 to 1 in 94% and 2 in 6% of patients. In HA twice-daily RT, grade > or = 4 acute esophagitis was noted in two of five (40%), two of seven (29%), four of six (67%), and five of six patients (86%) at 50 (1.25 Gy twice daily), 45, 50, and 55.5 Gy in 1.5 Gy twice daily, 5 d/wk, respectively. Grade > or = 3 pulmonary toxicity was not seen in any of these 24 patients. Therefore, the MTD for HA twice-daily RT was judged to be 45 Gy in 30 fractions over 3 weeks. In daily RT, grade > or = 4 acute esophagitis was noted in zero of four, zero of four, one of five (20%), and two of six patients (33%) at 56, 60, 66, and 70 Gy on a schedule of 2 Gy per fraction per day, five fractions per week. Grade > or = 3 pneumonitis was not observed in any of the 19 patients. Thus, the MTD for daily RT was judged to be at least 70 Gy in 35 fractions over 7 weeks. Grade 4 granulocytopenia and thrombocytopenia were observed in 53% and 6% of patients, respectively, during the first three cycles of PCE. During chemotherapy cycles 4 to 5, grade 4 granulocytopenia and thrombocytopenia were noted in 43% and 29% of patients at 45 Gy in 30 fractions over 3 weeks (MTD) by HA twice-daily RT and 50% and 17% at 70 Gy in 35 fractions over 7 weeks (MTD) by daily RT, respectively. The overall tumor response consisted of complete remission (CR) in 51% (24 of 47), partial remission (PR) in 38% (1 8 of 47), and stable disease in 2% (one of 47). The median survival time of all patients was 24.4 months and 2- and 3-year survival rates were 53% and 28%, respectively. With regard to the different radiation schedules, 2- and 3-year survival rates were 52% and 25% for the HA twice-daily and 54% and 35% for the daily RT cohorts. CONCLUSION: The MTD of HA twice-daily RT was determined to be 45 Gy in 30 fractions over 3 weeks, while it was judged to be at least 70 Gy in 35 fractions over 7 weeks for daily RT. A phase III randomized trial to compare standard daily RT with HA twice-daily RT at their MTD for local tumor control and survival would be a sensible research in searching for a more effective RT dose-schedule than those that are being used currently.

Adult↗

PubMed1998

Association between plasma HDL-cholesterol concentration and Taq1B CETP gene polymorphism in non-insulin-dependent diabetes mellitus.

The effects of CETP gene Taq1B polymorphism on plasma lipoproteins were investigated in 176 patients with non-insulin-dependent diabetes mellitus. The distribution of CETP genotypes was similar to that previously described in the general population. A significant association was found between CETP genotype and both CETP and HDL cholesterol (HDL-c) concentrations. B1B1 had the highest CETP and the lowest HDL-c whereas B2B2 had the lowest CETP and the highest HDL-c. However, HDL-c was not correlated with CETP concentration, even when genetic groups were separately considered. By multivariate analysis, the determinants of HDL were body mass index, triglycerides concentration, net mass CE transfer, and CETP genotype. No association was found between CETP genetic groups and HDL or LDL size distribution. In contrast, net mass CET was positively and HDL and LDL sizes were negatively correlated with plasma triglyceride concentration. Overall, our work demonstrates that, in a population of diabetic patients where lipoprotein-related parameters vary over a large range, the association of CETP gene polymorphism with HDL-c is independent of plasma CETP concentration.

Adult↗

PubMed1997

Radioactive technetium-99m labelling of Salmonella abortusovis for the assessment of bacterial dissemination in sheep by in vivo imaging.

We report the development and validation of a 99mTc-labelling technique of bacteria, applied to Salmonella abortusovis. The radioactive labelling is obtained using a pre-tinning step of the cells followed by direct incubation of S. abortusovis suspension with 99mTc-pertechnetate. Several procedures with different amounts of stannous tin (SnF2 or SnCl2) were evaluated. The selected method, respectful of bacterial viability, provided a 30% labelling yield. Viability of 99mTc-labelled bacteria was assessed by flow cytometry using rhodamine 123 and was demonstrated to be unchanged, turbidimetric measurements showing only a slight increase in the growth rate for radiolabelled cells. Incubation of 99mTc-labelled S. abortusovis with pronase, saponine and urea demonstrated labelling stability and suggested an intra-cellular localization for 99mTc. A preliminary study was also conducted in sheep to evaluate the value of the imaging of radiolabelled S. abortusovis. Spatial and temporal patterns of their in vivo dissemination in the lymphatic system after a sub-cutaneous injection were compared with control lymphoscintigraphic agents. These imaging data supported the assumption that the radioactivity detected in vivo was proportional to the number of 99mTc-labelled bacteria.

Animals↗

PubMed1997

Reversion of multidrug resistance with polyalkylcyanoacrylate nanoparticles: towards a mechanism of action.

Polyalkylcyanoacrylate (PACA) nanoparticles loaded with doxorubicin allowed multidrug resistance to be overcome in vitro. However, increased cytotoxicity is not always correlated with an increased level of intracellular drug. Although we have previously shown that PACA nanoparticles are not endocytosed by tumour cells, we report here that a direct interaction between nanoparticles and cells is a necessary requirement for overcoming resistance. In addition, the results showed that the degradation products of PACA (mainly polycyanoacrylic acid) in the presence of doxorubicin are able to increase both accumulation and cytotoxicity, thus suggesting the formation of a doxorubicin-polycyanoacrylic acid ion pair. It is therefore concluded that resistance is overcome as a result of both the adsorption of nanoparticles to the cell surface and increased doxorubicin diffusion by the accumulation of an ion pair at the plasma membrane.

Animals↗

PubMed1997

Aortic root abscess with fistula formation.

Aortic root abscess is a common complication of aortic valve endocarditis. However, aortic root abscess and formation of a fistula from the aortic root to the right ventricular outflow tract in the setting of a native aortic valve and previous repair of an aortic dissection with a Dacron graft is an uncommon event. Transesophageal echocardiography is superior to transthoracic echocardiography for the diagnosis of aortic root abscess. To our knowledge, no studies have compared the diagnostic value of cardiac MRI with transesophageal echocardiography for this condition.

Abscess↗

PubMed1997

In vitro cellular responses from sheep draining lymph node cells after subcutaneous inoculation with Salmonella abortusovis.

Salmonella abortusovis infection leads to ovine abortion. The basis for immunity against this infection is unknown. Immune responses were studied from prescapular lymph node (PSLN) cells of sheep infected with either a subcutaneous inoculation of virulent (15/5) or a vaccine (Rv6) strain and compared with those of uninfected sheep. PSLN cell phenotypes were characterized by immunofluorescence staining associated with flow cytometry. The in vitro responses were analysed using the PSLN cell proliferative response to several antigens, their secreted IL-2-like activities and their level of nitric oxide (NO) release. The phenotype analyses showed that the CD4(+)-T cell percentages decreased whereas B and MHC-II+ cell percentages increased in the infected sheep. This phenomenon occurred earlier for the virulent strain. The PSLN enlargement was greater and in vitro proliferation more frequent for the sheep infected with the virulent strain compared with the vaccine-infected ones. Proliferation occurred as a result of cell exposure to whole killed bacteria or to the cell wall fraction from S abortusovis but not to the homologous lipopolysaccharide. The secreted IL-2-like activities increased in parallel. The mitogenic response to concanavalin A decreased for infected sheep. For infected sheep, the level of NO release was maximal at the beginning of the infection. It was downregulated by in vitro exposure to S abortusovis antigens but remained unchanged for concanavalin A. NO release was not detected in uninfected sheep. This preliminary investigation provided some keys to the understanding of ovine response to S abortusovis infection and suggested that it shared common features with the mouse immune response.

Abortion, Veterinary↗

PubMed1997

The impact of managed care on women's health research: innovation versus renovation.

The success of managed care organizations (MCOs) is correlated to its ability to reduce health care costs. Increasingly, however, MCOs' success in providing quality care has been questioned. Of particular interest to the American Medical Women's Association will be MCOs' impact on women's health research, women's health researchers, and women's health. The authors conclude that MCOs will influence both the type and extent of clinical research performed. MCOs will increase the clinical research focus on prevention and medical effectiveness studies which will have a particular benefit for women. At the same time, MCOs will decrease the traditional focus on clinical trials designed to evaluate medical efficacy. If current trends continue, the ultimate impact of MCOs on women's health research will yield improved processes for providing care without improved technologies for providing cure.

Clinical Trials as Topic↗