Glucose biosensor based on functionalized ZnO nanowire/graphite films dispersed on a Pt electrode.

We present a glucose biosensor based on ZnO nanowire self-sustained films grown on compacted graphite flakes by the vapor transport method. Nanowire/graphite films were fragmented in water, filtered to form a colloidal suspension, subsequently functionalized with glucose oxidase and finally transferred to a metal electrode (Pt). The obtained devices were evaluated using scanning electron microscopy, energy-dispersive x-ray spectroscopy, cyclic voltammetry and chronoamperometry. The electrochemical responses of the devices were determined in buffer solutions with successive glucose aggregates using a tripolar electrode system. The nanostructured biosensors showed excellent analytical performance, with linear response to glucose concentrations, high sensitivity of up to ≈17 µA cm(-2) mM(-1) in the 0.03-1.52 mM glucose concentration range, relatively low Michaelis-Menten constant, excellent reproducibility and a fast response. The detection limits are more than an order of magnitude lower than those achievable in commercial biosensors for glucose control, which is promising for the development of glucose monitoring methods that do not require blood extraction from potentially diabetic patients. The strong detection enhancements provided by the functionalized nanostructures are much larger than the electrode surface-area increase and are discussed in terms of the physical and chemical mechanisms involved in the detection and transduction processes.

Interferon gamma receptor deficient mice are resistant to endotoxic shock.

Antibody neutralization studies have established interferon gamma (IFN-gamma) as a critical mediator of endotoxic shock. The advent of IFN-gamma receptor negative (IFN gamma R-/-) mutant mice has enabled a more direct assessment of the role of IFN-gamma in endotoxin (lipopolysaccharide [LPS]-induced shock. We report that IFN gamma R-/- mice have an increased resistance to LPS-induced toxicity, this resistance manifesting well before the synthesis and release of LPS-induced IFN-gamma. LPS-induced lymphopenia, thrombocytopenia, and weight loss seen in wild-type mice were attenuated in IFN gamma R-/- mice. IFN gamma R-/- mice tolerated 100-1,000 times more LPS than the minimum lethal dose for wild-type mice in a D-galactosamine (D-GalN)/LPS model. Serum tumor necrosis factor (TNF) levels were 10-fold reduced in mutant mice given LPS or LPS/D-GalN. Bone marrow and splenic macrophages from IFN gamma R-/- mice had a four- to sixfold decreased LPS-binding capacity which correlated with similar reduction in CD14. Serum from mutant mice reduced macrophage LPS binding by a further 50%, although LPS binding protein was only 10% reduced. The expression of TNF receptor I (p55) and II (p75) was identical between wild-type and mutant mice. Thus, depressed TNF synthesis, diminished expression of CD14, and low plasma LPS-binding capacity, in addition to blocked IFN-gamma signaling in the mutant mice, likely to combine to manifest in the resistant phenotype of IFN gamma R-/- mice to endotoxin.

In vivo gene delivery and stable transduction of nondividing cells by a lentiviral vector.

A retroviral vector system based on the human immunodeficiency virus (HIV) was developed that, in contrast to a murine leukemia virus-based counterpart, transduced heterologous sequences into HeLa cells and rat fibroblasts blocked in the cell cycle, as well as into human primary macrophages. Additionally, the HIV vector could mediate stable in vivo gene transfer into terminally differentiated neurons. The ability of HIV-based viral vectors to deliver genes in vivo into nondividing cells could increase the applicability of retroviral vectors in human gene therapy.

Cytokine regulation of TNF-alpha mRNA and protein production by unprimed macrophages from C57Bl/6 and NZW mice.

It is well known that bacterial lipopolysaccharide (LPS) induces the synthesis of tumor necrosis factor alpha (TNF-alpha) and other inflammatory cytokines by primary monocytes and macrophages and that the Th1 lymphokines, interleukin-2 (IL-2) and interferon-gamma (IFN-gamma), augment this response. We investigated the ability of IL-2 and IFN-gamma to induce the production of TNF-alpha mRNA and protein independently of LPS and the modulation of this response by macrophage colony-stimulating factor (M-CSF) and IL-10. We found that IL-2 and IFN-gamma were both able to induce the accumulation of TNF-alpha mRNA, albeit with slower kinetics than LPS, and that they acted synergistically. However, very little TNF bioactivity was secreted by lymphokine-stimulated macrophages unless LPS was also added. This finding underscores the importance of translational effects in the control of TNF production. M-CSF and IL-10 strongly inhibited TNF production at the level of both mRNA and bioactivity but had no effect on the production of IL-6. Bone marrow-derived or thioglycollate-elicited macrophages from the NZW mouse strain, which have been reported to be deficient in their ability to produce TNF, were at least as responsive to LPS or lymphokines as those taken from the C57Bl/6 strain and were similarly affected by M-CSF and IL-10. Therefore, the genetic defect of NZW mice is not a primary deficiency in TNF production.

Enhancement of murine macrophage binding of and response to bacterial lipopolysaccharide (LPS) by LPS-binding protein.

We have studied the effects of highly purified rabbit lipopolysaccharide (LPS)-binding protein (LBP) on the ability of murine bone marrow-derived macrophages to respond to bacterial LPS. Macrophage responses studied include the secretion of tumor necrosis factor alpha, production of arginine-derived nitrite (NO2-), and killing of an intracellular pathogen, Leishmania enriettii. Macrophages from either CBA or LPS-hyporesponsive C3H/HeJ mice exhibited significantly greater sensitivity to LPS in the presence of LBP. Furthermore, both CBA and C3H/HeJ macrophages demonstrated an LBP-dependent enhancement of LPS binding. These results suggest that C3H/HeJ macrophages are capable of binding LPS-LBP complexes and support the hypothesis that hyporesponsiveness in this strain involves a step subsequent to LPS binding. Furthermore, these findings provide additional evidence of the important role played by the acute-phase plasma protein LBP in modifying host response to LPS.

Human immunodeficiency virus type 1 hijacks host cyclophilin A for its attachment to target cells.

Our laboratory has identified a new facet of human immunodeficiency virus type 1 (HIV-1) entry. We demonstrated that the incorporation of host cyclophilin A (CypA) into nascent viruses is absolutely required for HIV-1 attachment to target cells. Although CypA is initially incorporated into the interior of the virus, we found that during maturation CypA relocates to the viral surface. Our work indicates that exposed CypA mediates HIV-1 attachment to target cells via heparans. We believe that this interaction between CypA and heparan represents the initial step in HIV-1 entry.

Radioimmunoassay versus flow cytometric assay to quantify LPS-binding protein (LBP) concentrations in human plasma.

LPS-binding protein (LBP) is an acute phase protein present in plasma, that has been shown to play a major role in sensitizing monocytes to LPS. We describe here two assays to quantify LBP in plasma. The first assay made use of monophosphoryl lipid A to capture LBP in human plasma, and LBP was detected by radiolabeled anti-LBP IgG. The second assay measured LBP by flow cytometry, using LBPs ability to present LPS to the CD14 receptor present on monocytes. Both assays had a similar level of sensitivity, that allowed the quantification of LBP in human plasma.

Direct current catheter ablation of an accessory pathway in a recipient with refractory reciprocal tachycardia.

A recurrent reciprocating tachycardia developed in a 45-year-old man 2 years after heart transplantation. Electrocardiograms of both donor and recipient were normal, without patent preexcitation. An electrophysiologic study showed a left-sided Kent bundle with only retrograde conduction property. Because antiarrhythmic therapy was unsuccessful, direct current catheter ablation was performed. Since this procedure the patient remained asymptomatic without antiarrhythmic therapy.

Characterization and detection of naturally occurring antibodies against IL-1 alpha and IL-1 beta in normal human plasma.

During the development and testing of a radioreceptor assay (RRA) for human IL-1, we have detected and identified the presence of auto-antibodies to IL-1 in normal human plasma (NHP). The RRA is based on the competition between human 125I-labeled rIL-1 alpha and standard or unknown quantities of IL-1 alpha or IL-1 beta for binding to a limited amounts of IL-1 receptor (IL-1R) isolated from the EL4 mouse thymoma cell line. NHP from 20 out of 100 unselected blood donors were found to completely inhibit the binding of 125I-labeled IL-1 alpha to its receptor, suggesting the presence in these NHP samples of either abnormal amounts of IL-1 or of a factor binding to the 125I-labeled IL-1 alpha. Special care was taken to ascertain that the inhibitory factors were antibodies and not soluble IL-1 receptor antagonist. When plasma samples with inhibiting activity were incubated with labeled IL-1 alpha and chromatographed on a Sephadex G200 column, they were found to contain 125I-labeled complexes with an apparent molecular weight of 150-200kD. The IL-1 binding factor could be eliminated from plasma by incubation with protein A-Sepharose, suggesting that it consisted in IgG antibodies directed against IL-1. Furthermore, the antibody nature of the inhibiting factor was confirmed by its binding to purified rIL-1 coupled to Sepharose. Screening of 200 NHP samples by incubation with 100 pg of 125I-labeled IL-1 followed by precipitation with 12% of polyethylene glycol (PEG) confirmed that about 25% of NHP contain detectable IgG antibodies to IL-1 alpha, while only 2% of NHP contain antibodies to IL-1 beta. No correlation between the presence of these anti-IL-1 antibodies and any particular major histocompatibility complex or any pathological conditions was detected. We suggest that all serum samples assayed for IL-1 alpha or IL-1 beta content should be pretested with the PEG precipitation assay described here.

A randomized double-blind trial of intravenous trimetazidine as adjunctive therapy to primary angioplasty for acute myocardial infarction.

BACKGROUND: Despite high patency rates, primary angioplasty for myocardial infarction does not necessarily result in optimal myocardial reperfusion and limitation of infarct size. Experimentally, trimetazidine limits infarct size, decreases platelet aggregation, and reduces leukocyte influx into the infarct zone. To assess trimetazidine as adjunctive therapy to primary angioplasty for acute myocardial infarction a prospective, double-blind, placebo-controlled pilot trial was performed. METHODS: 94 patients with acute myocardial infarction were randomized to receive trimetazidine (40 mg bolus followed by 60 mg/day intravenously for 48 h) (n=44) or placebo (n=50), starting before recanalization of the infarct vessel by primary angioplasty. Patients underwent continuous ST-segment monitoring to assess return of ST-segment deviation to baseline and presence of ST-segment exacerbation at the time of vessel recanalization. Infarct size was measured enzymatically from serial myoglobin measurements. Left ventricular angiography was performed before treatment and repeated at day 14. RESULTS: Blinded ST segment analysis showed that despite higher initial ST deviation from baseline in the trimetazidine group (355 (32) vs. 278 (29) microV, P=0.07), there was an earlier and more marked return towards baseline within the first 6 h than in the placebo group (P=0.014) (change: 245 (30) vs. 156 (31) microV respectively, P=0.044). There was a trend towards less frequent exacerbation of ST deviation at the time of recanalization in the trimetazidine group (23.3 vs. 42.2%, P=0.11). There was no difference in left ventricular wall motion at day 14, or in enzymatic infarct size. There was no side effect from treatment. Clinical outcomes were similar between groups. CONCLUSION: Trimetazidine was safe and led to earlier resolution of ST-segment elevation in patients treated by primary angioplasty for acute myocardial infarction.

Characterisation of bovine lipopolysaccharide binding protein and the in vivo acute phase response to Pasteurella haemolytica Type A.

Lipopolysaccharide binding protein (LBP) is a liver-derived acute phase protein which is implicated in modulating the host responses to lipopolysaccharide (LPS) from Gram-negative bacteria. LBP interacts with circulatory LPS to form complexes which bind to the CD14 receptor or cells of the monocytic lineage and neutrophils resulting in their activation. This causes the release of mediators and cytokines which are responsible for initiating the acute phase response. LBP-like activity has now been identified in bovine serum and in this study LBP has been purified from acute phase bovine serum using ion exchange chromatography. On sodium dodecyl sulphate polyacrylamide electrophoresis, bovine LBP demonstrated a single band with a molecular mass of 58 kDa. Bovine LBP enhanced the binding of LPS to human monocytes while enzymatic removal of the CD14 receptor abrogated this interaction. Furthermore, bovine LBP increased the sensitivity of monocytes to LPS by at least 100-fold. Depletion of LBP by means of antibodies to bovine LBP inhibited the serum mediated LPS binding to monocytes. Antibodies to rabbit LBP or recombinant human LBP did not cross-react with bovine LBP. Studies on the kinetics of LBP activity in calves during the acute phase response demonstrated a four-fold increase in the serum concentration 36 h after a single intratracheal inoculation of Pasteurella haemolytica A1. The findings of this study indicate that cattle possess a LPS detection mechanism comparable to that described in man and experimental animals in which LBP forms complexes in serum with circulatory LPS enhancing the signal to the immune system to mount a host response. The isolation of LBP will allow further investigations into LBP-mediated responses to LPS in cattle.

[Ventricular tachycardia caused by bundle branch reentry]. / Les tachycardies ventricularies par réentrées de branche à branche.

Ventricular tachycardia by bundle branch reentry is a special type of ventricular tachycardia. A rare arrhythmia, it occurs in very particular conditions of ventricular dilatation and conduction defects. The diagnosis is based on electrophysiological findings associating a His potential preceding the ventriculogramme with a HV interval comparable to that observed in sinus rhythm, and spontaneous variations of the cycle length between two ventriculogrammes preceded by those of the His potentials. Contrary to what is observed in other forms of ventricular tachycardia, pacing is possible from the atrium without changes of the QRS complexes and the presence of fusion complexes excludes the diagnosis. Treatment consists of radiofrequency ablation of the right bundle branch.

[Treatment by endocavitary fulguration of recurrent ventricular tachycardia caused by right ventricular dysplasia]. / Traitement par électrofulguration endocavitaire d'une tachycardie ventriculaire récidivante par dysplasie ventriculaire droite.

A 27 year old man had recurrent ventricular tachycardia since the age of 16. Different antiarrhythmic drugs were used successively without success (mexiletine, amiodarone, acebutolol, propafenone, sotalol). The diagnosis of VT due to arrhythmogenic right ventricular dysplasia was suggested by the morphology of the tachycardia (left-sided delay), surface ECG appearances (right bundle branch block and potential after the QRS in right precordial leads) and the presence of delayed potentials on right ventricular endocavitary recordings. However, there were no obvious RV changes on echo or angiographic examination. The arrhythmogenic zone was localised in the postero-basal zone of the RV using three electrophysiological criteria: the recording of delayed systolic potential in sinus rhythm which overlapped into diastole during tachycardia, mapping of ventricular depolarisation during VT and results of RV "pacemapping" reproducing the appearances of the spontaneous tachycardia. VT was reproducible on stress testing (non-sustained VT at the beginning of the recovery phase) and on endocavitary stimulation. One 250 joule electric discharge between the endocavitary electrodes and a large dorsal surface electrode prevented any further attacks without antiarrhythmic therapy (follow-up: one year). Control electrophysiological investigation after 4 months showed another potentially arrhythmogenic zone which is quiescent at present.

[Comparative study of auricular stimulation by transesophageal and endocavitary approach for evaluating sinus and atrioventricular node function]. / Etude comparée de la stimulation auriculaire par voie transoesophagienne et endocavitaire pour l'évaluation de la fonction sinusale et du noeud atrio-ventriculaire.

The purpose of this study was to find out whether non-invasive transoesophageal pacing could effectively replace right intra-atrial pacing for the indirect evaluation of sinus node and atrioventricular (AV) node function. In a population of 17 patients the corrected sinus node recovery time (CSRT), the atrio-sinu-atrial conduction time (ASACT) and Wenckebach's point (W) were calculated by intracavitary pacing, then by transoesophageal pacing. There was no significant difference between the two methods in pre-pacing sinus cycle. With right intra-atrial pacing, mean CSRT value was 365 +/- 54 ms (with 5 values greater than 520 ms), mean ASACT value was 229 +/- 29 ms (with 8 values greater than 220 ms), and W occurred at a mean cycle length of 425 +/- 29 ms. With transoesophageal pacing, mean CSRT value was 406 +/- 87 ms (with 5 values greater than 520 ms), mean ASACT value was 222 +/- 17 ms (with 8 values greater than 220 ms), and W occurred at a mean cycle length of 408 +/- 26 ms. The two methods correlated very closely for CSRT and W (r = 0.97) and relatively well for ASACT (r = 0.84). The number of CSRT and ASACT values regarded as prolonged was the same with the two methods; 84% of recorded (i.e. maximal) CSRT values occurred with the same length of pacing cycle. There was no statistically significant difference between the two methods in the calculation of CSRT and ASACT, but W occurred at a slightly shorter cycle (p less than 0.05) with transoesophageal pacing. Thus, transoesophageal pacins is a non-invasive, easy to perform method for indirect exploration of sinus node and AV node function in patients who do not require subnodal conduction studies.

[Myocardial infarction and anti-ethinylestradiol antibody. Apropos of a case in an 18-year-old woman]. / Infarctus du myocarde et anticorps anti-éthinylestradiol. A propos d'un cas chez une jeune femme de 18 ans.

An 18-year-old woman presented with a large anterior myocardial infarction. Her cardiovascular risk factors were cigarette smoking in moderation and oral contraception with a synthetic oestroprogestative pill prescribed a few months previously. Coronary angiography showed occlusion of the left anterior descending artery but no other lesions. Biological investigations excluded an abnormality of coagulation. Antibodies to synthetic steroids (ethinylestradiol and progesterone) and circulating immune complexes were found in the serum. The role of antiethinylestradiol antibodies in the mechanism of myocardial infarction is discussed. These antibodies are present in 30 per cent of women taking oral contraceptives and their titres are significantly higher in 90 per cent of women who develop vascular thrombosis unrelated to atherosclerosis. The mechanism of the thrombogenic action of the antibodies and circulating immune complexes is also considered.

[Myocardial morphological changes related to sodium intake in normotensive and hypertensive patients never treated before]. / Modifications morphologiques myocardiques liées à l'apport sodé chez le sujet normotendu et l'hypertendu jamais traité.

Several factors have been implicated in the pathogenesis of myocardial hypertrophy, and the role of sodium has recently been suggested. In the present study, we assessed the influence of dietary sodium on the degree of left ventricular hypertrophy (LVH) and LV structure in 30 normotensive (NT) subjects aged 34 +/- 11 years (mean +/- SD) and 50 patients (39 +/- 10 years) with mild essential hypertension EH (canal blood pressure 154 +/- 16/96 +/- 11 mmHg), who had never received antihypertensive drugs. Posterior wall thickness (PWT) and left ventricular mass (LVM) were measured by M-mode echocardiography and urinary sodium excretion (UNa, mmol/24h) was taken as an index of sodium intake. In NT and EH, LVM was directly correlated with UNa (r = 0.48 and 0.49; p less than 0.006 and 0.002, respectively). A stepwise multiple regression analysis confirmed that UNa was a determinant of LVM independently of sex, age, and body weight in the two groups. In NT the correlation with UNaV was the result of an increase of the end-diastolic diameter without change in PWT whilst in EH it was the consequence of an increase in wall thickness (R = 0.49, p less than 0.0001) without a modification of LV diameter. These results suggest that salt intake may be an important determinant of cardiac structural adaptation in both NT and EH subjects; however, only EH have a salt sensitive LV wall hypertrophy.

[Transesophageal stimulation in the treatment of atrial flutter and tachysystole]. / La stimulation transoesophagienne dans le traitement du flutter et de la tachysystolie auriculaire.

Transoesophageal left atrial pacing was used to reduce 102 episodes of ectopic atrial rhythms (79 common flutters and 23 ectopic tachycardias) in 83 patients (64 men, 19 women) aged 33 to 85 years (average 61 years). Overdrive pacing, at a faster rate than that of the spontaneous rhythm, was delivered via a bipolar pacing catheter introduced nasally and positioned behind the atrium under fluoroscopic and/or electrocardiographic control. Long pulse durations (up to 20 ms) were used to capture the atria with intensities of less than 20 mA for better tolerance. The overall results were: a) conversion to sinus rhythm in 60.8 p. 100 of cases (47 p. 100 directly and 13.8 p. 100 after transient atrial fibrillation), b) atrial fibrillation lasting over 24 hours in 7.8 p. 100 of cases, c) failure (31.4 p. 100) due to non-capture or intolerance (20.6 p. 100) or recurrence of the arrhythmia after transient atrial fibrillation (10.8 p. 100). Atrial flutter is more accessible to pacing than tachycardia (restoration of sinus rhythm in 63.3 p. 100 and 52.2 p. 100, respectively). Arrhythmias in the postoperative period of cardiac surgery, and isolated and recent arrhythmias were more easily converted. Prior antiarrhythmic therapy did not seem to improve results. Fifty per cent of failures of oesophageal pacing were converted to sinus rhythm by endocavitary pacing. These results show that atrial flutter or tachycardia may be successfully treated by oesophageal pacing in over 50 p. 100 of cases without having to use other forms of electrotherapy (endocavitary pacing or cardioversion).

[Mid-term outcome of escape rhythm after radiofrequency ablation of the atrioventricular junction]. / Evolution à moyen terme du foyer d'échappement après ablation par radiofréquence de la jonction auriculoventriculaire.

UNLABELLED: Mid-term outcome of the underlying escape rhythm developed after radiofrequency ablation of the atrio-ventricular junction was studied in 50 consecutive patients (28 women and 22 men with a mean age of 66.2 +/- 9.6 years). The escape rhythm was assessed immediately after ablation and after 13.7 +/- 8 months. At the end of ablation: an escape rhythm was present in 38 patients (76%), with a mean rate of 40.7 +/- 9.7 beats/min and a QRS morphology identical to the preablation QRS morphology in 22 patients (58%). At follow-up: an escape rhythm was present in 37 patients (74%), with a slower mean rate of 36.4 +/- 6.8 beats/min (p < 0.05) and an unchanged QRS morphology in 87.5% of the patients. Patients presenting with an escape rhythm at follow-up were more frequently found to have a postablation escape rhythm (p < 0.01). Escape rhythm presence at follow-up was not influenced by age, presence of a cardiac disease, continuation of an antiarrhythmic treatment after ablation, use of a bilateral approach for ablation or number of radiofrequency applications. CONCLUSION: after abrupt inhibition of the stimulation, an escape rhythm was present only in 74% of the patients 13.7 +/- 8 months after atrio-ventricular junction radiofrequency ablation. QRS morphology was identical to the preablation morphology in 57% of the patients.

[Evaluation of the left-to-right shunt in interatrial septal defects (ostium secundum) using Doppler echocardiography. Apropos of 12 cases]. / Evaluation du shunt gauche-droit dans les communications interauriculaires (ostium secundum) par échographie-Doppler. A propos de 12 cas.

In 12 patients with inter-atrial communication (ostium secundum) (IAC-OS), and ages ranging between 8 and 63 years (mean = 21 years), the ratio between pulmonary and systemic flow (QP/QS) was evaluated with the use of Doppler ultrasonography and compared with the QP/QS obtained by oxymetric measurement during catheterization. The pulmonary or systemic flow is evaluated from the diameter of the opening (d) and the velocity curve (ITV) recorded by pulsated Doppler in the aorta and the pulmonary artery; Q = d2/4 x ITV x heart rate both examinations (sonogram and catheterization) are performed in less than 24 hours. The results show a good correlation between both methods (R = 0.948) (Y = 0.756 X + 0.692). There is no significant variation between intra- or inter-observer. The findings of this study are comparable to those already published; the main difficulty in evaluating of the QP/QS by Doppler sonography are related to the measurement of the pulmonary diameter and there recording of good velocity curves. The QP/QS evaluated by Doppler sonography from a simplified calculation method advocated by Oloez et al. (QP/QS = d2 Ap x V max Ap/d2 Ao x V max Ao were compared, in retrospect, to the data provided by catheterization. The correlation is also satisfactory (R = 0.893). The Doppler ultrasonography is therefore a reliable and reproducible method in as far as the measurement of QP/QS in young or adults subjects affected with IAC OS.

[Myoglobin: an early indicator of myocardial infarction during heart surgery]. / La myoglobine: un marqueur précoce de l'infarctus myocardique au cours de la chirurgie cardiaque.

Plasma myoglobin was measured in 40 patients before, during and after cardiac surgery under cardiopulmonary bypass, in order to study its value as an indicator of intra-operative myocardial damage. Myoglobin levels rose at cannulation, further increased during the operation and reached a peak 2 hours later; they began to decrease 6 hours after surgery and were back to normal 24 hours later. Myoglobin levels from induction of the anesthetics to the 6th post-operative hour were significantly higher in the 8 patients who developed intra-operative myocardial infarction than in the other patients. Thus, myoglobin is an early indicator of intra-operative myocardial ischaemia. An abnormal rise of myoglobin at induction of the anesthetics characterizes a group of patients at high risk of myocardial infarction during surgery.