The use of (oligonucleotide-maleic anhydride copolymer) conjugates in nucleic acid diagnostic assays: effect of the number of oligonucleotides per polymer on test sensitivity improvement.

(Polymer-oligonucleotide) conjugates were obtained via direct ON synthesis from the poly(ethylene-alt-maleic anhydride: PEMA) grafted onto glass bead surfaces. The effect of the ON number per polymer chain on binding was evaluated through Tm experiments. Results were correlated with ELOSA (Enzyme Linked Oligosorbent Assay) tests run with conjugates in the capture step.

Oligonucleotide-polymer conjugates: effect of the method of synthesis on their structure and performance in diagnostic assays.

Oligonucleotide-polymer conjugates have been described to improve the sensitivity of an enzyme-linked oligosorbent assay diagnostic test. To understand the influence of their structure and conformation in solution on the efficiency of the test during the capture step, two different ways of synthesizing these conjugates were compared. The first consisted of coupling 5' amino modified oligonucleotides to poly(maleic anhydride-alt-methylvinyl ether) and poly(maleic anhydride-alt-ethylene). The second resulted from direct synthesis of oligonucleotides from poly(maleic anhydride-alt-ethylene) previously grafted onto a controlled pore glass support. The different conjugates were analyzed by size-exclusion chromatography and viscometry. The former method for conjugate synthesis produced aggregates, which was not the case for the latter. These conjugates were then used in the capture phase of a hybridization assay using a HBV DNA target, on a bioMérieux VIDAS instrument. Different parameters were studied, such as the purity of the conjugate solution and the number of oligonucleotides per polymer chain. The amount of conjugate coated on the solid-phase receptacle surface at the time of the capture phase was evaluated by radioactive labeling. Finally, it was demonstrated that conjugates produced an amplification factor of 50 versus the capture oligonucleotide probe used as the reference. The detection limit reached 10(8) copies/mL.

Costs for acute myocardial infarction in a tertiary care centre and nationwide in France.

OBJECTIVE: We compared the estimated costs of coronary interventions from our hospital's cost accounting system with data from the French Diagnosis Related Group (DRG) cost database, taking the perspective of our hospital. DESIGN: Cost data on hospital resources used by patients hospitalised for acute myocardial infarction (MI), with and without complications, including deceased patients, were collected in a tertiary care university hospital located in Paris, France. The data were collected using the hospital's cost accounting system and then compared with the estimates provided by the DRG reimbursement schedule for similar conditions. MAIN OUTCOME MEASURES AND RESULTS: The estimated costs were 849 euro (EUR) for coronary angiography, EUR4762 for coronary angioplasty with stenting, and EUR4978 to 8067 for MI. The DRG reimbursement schedule provided for acute MI was EUR3920 to 5709. CONCLUSIONS: Although the current cost of treating acute MI in a teaching hospital is reasonably close to that in the current reimbursement schedule, rapid technological changes regarding both drugs and devices renders necessary a close monitoring of costs associated with the management of these acute care patients.

Economic evaluation of drug resistance genotyping for the adaptation of treatment in HIV-infected patients in the VIRADAPT study.

BACKGROUND: Costs of antiretroviral therapy for HIV-infected patients have increased at a time when most countries are attempting to contain health care costs. Part of this increase results from HIV drug resistance associated with virologic failure and a subsequent shift to more complex and costly therapies. Genotypic guided treatment is associated with better virologic outcome. However, it is not yet known whether it will be cost effective. METHODS: We present here an economic evaluation based on the results from the VIRADAPT study, a prospective, open-label, randomized trial comparing patients assigned to standard of care (n = 43), versus genotypic guided treatment (n = 64) for 6 months. Total follow-up for the extended trial was 1 year. Costs were computed from the viewpoint of the health care system. Hospitalization data were retrieved from the VIRADAPT study case report forms, costs were estimated from the cost of the corresponding diagnosis-related groups derived from the French national cost data base: these were actual costs and not charges. Data on the volume of tests prescribed, drugs, and clinic visits were retrieved from the VIRADAPT study database. The unit costs of tests and clinic visits were determined using the French national Social Security reimbursement price; costing of drugs used were based upon purchase price by either retail pharmacies or hospitals. Genotyping using TruGene HIV-1 assay was estimated at $500 per test from manufacturer's data (all figures in this paper are expressed in U.S. dollars). RESULTS: Total mean (standard deviation) yearly costs per patients were $20,412 (+/-$10, 129) in the standard of care group and $18,484 (+/-$9,652) in the genotyping group (p =.35). Drug costs represented 55% of total costs. There was a trend toward a decrease in drug costs in the genotyping arm (p =.07), the greatest reduction being in the decreased use of protease inhibitors in the genotyping arm. The additional expense of genotyping appeared to be offset by the savings obtained in drug costs. CONCLUSION: In our study, the cost of drug resistance testing is offset by a reduced use of protease inhibitors and their attendant costs. Although not reaching statistical significance, this trend in the reduction of drug costs and drug use presents a great interest for future trials.

Control of endemic methicillin-resistant Staphylococcus aureus: a cost-benefit analysis in an intensive care unit.

CONTEXT: Despite the success of some countries in controlling endemic methicillin-resistant Staphylococcus aureus (MRSA), such programs have not been implemented for some hospitals with endemic infection because of concerns that these programs would be costly and of limited benefit. OBJECTIVE: To compare the costs and benefits of an MRSA control program in an endemic setting. DESIGN AND SETTING: Case-control study conducted at a medical intensive care unit (ICU) of a French university hospital with a 4% prevalence of MRSA carriage at ICU admission. PATIENTS: Twenty-seven randomly selected patients who had ICU-acquired MRSA infection between January 1993 and June 1997, matched to 27 controls hospitalized during the same period without MRSA infection. MAIN OUTCOME MEASURES: Intensive care unit costs attributable to MRSA infection, computed from excess therapeutic intensity in cases using estimates from a cost model derived in the same ICU, were compared with costs of the control program, derived from time-motion study of nurses and physicians. The threshold for MRSA carriage that would make the control strategy dominant was determined; sensitivity analyses varied rates of MRSA transmission and ratio of infection to transmission, length of ICU stay, and costs of isolation precautions. RESULTS: The mean cost attributable to MRSA infection was US $9275 (median, $5885; interquartile range, $1400-$16,720). Total costs of the control program ranged from $340 to $1480 per patient. A 14% reduction in MRSA infection rate resulted in the control program being beneficial. In sensitivity analyses, the control strategy was dominant for a prevalence of MRSA carriage on ICU admission ranging from 1% to 7%, depending on costs of control measures and MRSA transmission, for infection rates greater than 50% following transmission. CONCLUSIONS: In this example of a hospital with endemic MRSA infection, selective screening and isolation of carriers on ICU admission are beneficial compared with no isolation.

A model to compute the medical cost of patients in intensive care.

OBJECTIVE: Our objective was to identify, among the information routinely collected on patients in intensive care units (ICUs), data that determine the total cost for a given patient. DESIGN: We developed a model that could help physicians in medical ICUs to estimate the cost of care for their patients when no cost data were available at the individual patient level. SETTING: A Medical ICU. PATIENTS AND PARTICIPANTS: The model was developed using a random sample of 73 patients admitted to the medical ICU in 1996 and 1997, validated by another random sample of 29 patients admitted during the same period. INTERVENTIONS: The actual medical variable cost per patient was computed from data on the total resources used (excluding personnel and fixed costs), collected from the patients' records plus pharmacy, laboratory and blood bank logs. The explanatory variables tested were: length of stay, nursing workload, severity of condition, and procedures recorded by a score [omega (omega)] including 3 components related to the frequency of procedure use. The model was constructed in a stepwise fashion, assuming a linear relation. Equations were tested on the basis of the residual mean square; criteria for inclusion and elimination of variables were the level of its partial regression coefficient and medical criteria. The model was validated by analysis of variance of the regression on a second population of 29 patients using the F-test. MAIN OUTCOME MEASURES AND RESULTS: The median length of stay was 7 days (range: 3 to 22 days). Mortality rate was 25%. Median medical variable cost was 805 Pounds (mean medical variable cost was 1738 Pounds, total cost was 6279 Pounds). The variables selected in the multiple regression model as relevant predictors of medical costs were: procedures recorded only once during the ICU stay irrespective of their reiteration (omega 1), procedures recorded every time they are performed (omega 2), procedures recorded daily in the ICU (omega 3) and the presence or absence of an invasive procedure (Kc). The final equation, calibrated with r2 of 0.826 and p > 0.0001, was: medical cost (Pounds) = 23 omega 1 + 53 omega 2 + 8 omega 3 + 2352Kc + 96. The validation with the other sample of 29 patients compared actual to predicted costs. Analysis of variance of the regression from the model was r2 = 0.596 (p > 0.05). CONCLUSIONS: Our standardised cost model is a possible approach to allow comparison of medical costs within and between ICUs.

[Does continuing medical education improve the way physicians conduct their practice?]. / La formation médicale continue améliore-t-elle le comportement des médecins?

OBJECTIVES: Physicians practicing in France are required to participate in continuing education programs in accordance with the code of deontology and the official decree on controlling medical expenditures. We reviewed the literature to analyze the efficacy of such training on the way physicians conduct their practice. METHODS: We examined the following educational methodologies: diffusion of educational documents or guidelines, conferences and presentations, interventions by opinion leaders, direct visits at the physician's office. The analysis was based solely on publications issuing from work considered to be valid in accordance with the Cochrane collaboration: intervention trials, chronological series, before-after studies with control group. RESULTS: The diffusion of educational material or more formal continuing education programs do not appear to have an effect on the way physicians conduct their practice. Interventions by opinion leaders have a demonstrated impact but are rarely judged clinically significant. Visits to the physician's office by specially trained health care workers have an effect but this mode of education is costly. CONCLUSIONS: The conventional strategies, such as simple information diffusion and continuing education programs, developed to promote an evolution of clinical practices appear to be the least effective methodologies.

Scoring method for assessing rate adaptive pacemakers: application to two different activity sensors.

To optimize programming of rate adaptive pacemakers (RAPs), we explored a new mathematical method to assess the performance of RAPs during daily-life tests, using customized Windows-based software. By stepwise discriminant analysis and linear regression, this method allows calculation of the acceleration and deceleration capacity of pacemakers and their general behavior during effort and recovery phases. Twenty-three patients (10 females and 13 males; 68 +/- 8 years) with chronic atrial fibrillation and a slow ventricular response were evaluated. They randomly received an accelerometer-controlled VVIR Dash Intermedics pacemaker (10 patients) or a vibration piezoelectric-controlled VVIR Sensolog III Siemens pacemaker (13 patients). All patients underwent the same test protocol: 6 minutes walking, 1.5 minutes climbing stairs, 1.5 minutes descending stairs, and 0.5 minutes sit-ups. By definition, the pacemaker responsiveness slope was programmed so that the heart rate response of paced patients during the walking test corresponded best to that of healthy controls. The slope was left unchanged for the other tests. We considered four scores: an acceleration score (EA score), an effort rate score (ER score), a deceleration score (RD score), and a recovery rate score (RR score). Scores ranged from -10 (hypochronotropic behavior of the pacemaker) to +10 (hyperchronotropic behavior), based on daily-life tests of 15 healthy controls (7 females and 8 males, 65 +/- 9 years). A score of 0 represented exact concordance with healthy controls. During stair descent, the Sensolog III produced excessive acceleration (EA score = +2.9 +/- 1.1) compared to: (1) stair climbing (EA score = -4.0 +/- 1.9; P = 0.01, with the same pacemakers); and (2) the Dash (+1.8 +/- 1.9; P = 0.04) and healthy controls (P = 0.02). The sit-up tests revealed a hypochronotropic response of both pacemakers compared to healthy controls, with a larger difference for the Sensolog III (EA score = -2.0 +/- 5.8; P = 0.04; RD score = -6.8 +/- 3.8' P = 0.02). We conclude that activity-driven pacemakers can accommodate brief activities, except for isovolumetric exercise such as sit-ups. During daily activities, accelerometer-driven pacemakers seem to provide a heart rate resoibse closer to that of healthy controls. Our new mathematical analysis is a simple and reproducible method for evaluating and quantifying the efficacy of any sensor-driven pacemaker.

In vivo metabolic profile of a phosphorothioate oligodeoxyribonucleotide.

Antisense phosphorothioate oligodeoxyribonucleotides (PS oligonucleotides) have the ability to inhibit individual gene expression in the potential treatment of cancer and viral diseases. Following administration in vivo, PS oligonucleotides are rapidly cleared from the plasma and distributed to various organs. However, the manner in which administered oligonucleotides are metabolized in plasma and tissues is poorly understood. In this study, a 25-mer PS oligonucleotide (GEM91) complementary to the gag gene mRNA of the human immunodeficiency virus (HIV-1) was administered to mice through intravenous injections to investigate its metabolism. The PS oligonucleotide was extracted from plasma at 1 hour postadministration and from kidney and liver at 24 hours postadministration. After extraction, the PS oligonucleotide and its metabolites were tailed with dA and annealed to a dT-tailed plasmid. The recombinant plasmid was ligated and used to transform competent bacteria. The region of interest containing the PS oligonucleotide was then sequenced. Our results show that degradation of the PS oligonucleotide in plasma was primarily from the 3'-end. However, in kidney and liver, degradation was primarily from the 3'-end, but a large proportion of the PS oligonucleotide was degraded from the 5'-end as well. We also studied the metabolism of PS oligonucleotide in plasma after 2-hour intravenous infusion in HIV-infected patients. The degradation of the PS oligonucleotide in plasma was primarily from the 3'-end. This study is important in understanding the metabolism of antisense PS oligonucleotide in vivo in general but also provides guidance for designing second-generation antisense oligonucleotides with improved stability and safety profile.

[Economic evaluation of the use of haematopoietic factors in managing malignant hemopathies]. / Evaluation économique de l'utilisation de facteurs de croissance hématopoïétiques dans la prise en charge des hémopathies malignes.

Economic evaluation of haematopoietic growth factors in the treatment of malignant hemopathies was undertaken along with clinical trials or retrospectives studies. The cost of the sole treatment was estimated to be 2,302 US$ per cycle. Cost-minimization analyses compared the cost of a treatment course (chemotherapy, bone marrow transplantation with and without haematopoietetic growth factors), and cost-effectiveness analyses estimated the cost per episode of averted febrile neutropenia. Results appear to be contradictory and do not allow definite conclusions about the existence of extra costs or of cost savings due to the introduction haematopoietetic growth factors, except in the case of filgrastim-mobilized peripheral blood progenitor cell transplantation.

Solid phase synthesis of the 5'-half of the initiator t-RNA from B. subtilis.

Using cyanoethyldiisopropylamino phosphoramidite chemistry, four oligonucleotides constituting a part of the sequence of the initiator t-RNA from B. subtilis were synthesized. For the protection of the exocyclic amino functions of bases, phenoxyacetyl group was used for adenine and guanine, and acetyl group was preferred for cytosine. With these labile groups, final deprotection of the oligonucleotides can be performed in milder conditions, allowing the incorporation of 5,6-dihydrouridine in a 35-mer constituting the 5'-end of the t-RNA.

Labile protecting groups in tRNA synthesis.

The use of labile protecting groups for the protection of the exocyclic amino function of adenine, guanine and cytosine has two main advantages in RNA synthesis. Final deprotection in concentrated aqueous ammonia takes place in milder conditions which are more compatible with the sensitivity of oligoribonucleotides towards alkali-conditions. The introduction of fragile bases such as certain modified bases encountered in the primary structure of t-RNA is feasible. The chemical synthesis of RNA fragments constituting the primary structure of B. subtilis f-methionine t-RNA is described.

[Characteristics and evolutive data of chronic respiratory diseases after respiratory intensive care. Evaluation of the Pneumology Department of the Pavillon Saint-François in Strasbourg between 1980 and 1985]. / Caractéristiques et données évolutives des affections respiratoires chroniques après réanimation respiratoire. (Bilan du service de pneumologie du Pavillon Saint-François de Strasbourg entre 1980 et 1985).

Between 1980 and 1985, 66 patients with chronic obstructive lung disease (respiratory deficit of the restrictive type) were admitted to our department after an episode of acute respiratory failure treated with assisted ventilation in an intensive care unit. These patients were in a particularly poor clinical condition, due to their previous long stay in the intensive care unit (mean 43 days), the high percentage of tracheotomies (mean 44%), the loss of autonomy of movement in 30% of the cases and the presence of an associated pathology in 45% of the patients. These data explain the high mortality observed in this group: 40% of the patients died within one year of the acute respiratory failure episode. Other prognostic factors, notably the patients' nutritional status, must also be taken into account.

[Preliminary results concerning the value of chemotherapy in the treatment of inoperable bronchial carcinoma (excluding small-cell anaplastic carcinoma)]. / Résultats préliminaires concernant l'intérêt d'une chimiothérapie dans le traitement des carcinomes bronchiques inopérables (à l'exclusion des carcinomes anaplasiques à petites cellules).

Inoperable non- microcellular primary bronchial carcinomas have been reputed up to now to be chemo-resistant. The introduction of Cis-platinum into a polychemotherapy protocol leads to revision of this concept. The authors report the preliminary results of a polychemotherapy protocol (including Cis-platinum, Vindesine, CCNU, Cyclophosphamide) associated, in cases of non- metastasized carcinomas, with radiotherapy to the tumour itself, the mediastinum and the supraclavicular fossae. These results confirmed the value of such chemotherapy in forms with metastases. In localised inoperable forms, conclusions could be reached only on the basis of a randomised comparative trial of chemotherapy + radiotherapy versus radiotherapy alone.