Symmetric subresultants and applications

Schur’s transforms of a polynomial are used to count its roots in the unit disk. These are generalized then by introducing the sequence of symmetric subresultants of two polynomials. Although they do have a determinantal definition, we show that they satisfy a structure theorem which allows us to compute them with a type of Euclidean division. As a consequence, a fast algorithm based on a dichotomic process and FFT is designed.     

Effects of norepinephrine on right ventricular function in septic shock patients

OBJECTIVE: To study the effects of norepinephrine on right ventricular function in patients with hyperdynamic septic shock. DESIGN: Prospective, open study. SETTING: A 15 bed ICU in a university hospital. PATIENTS: 9 patients with hyperdynamic septic shock (SBP < 90 mmHg, Cl > or = 4 l.min-1.m-2, SVRI < or = 850 dynes.s.cm-5m-2 and oliguria). INTERVENTIONS: Plasma volume expansion was used to correct a suspected volume deficit and then, norepinephrine infusion was started and titrated to restore systemic blood pressure to the normal range (mean infusion rate: 1.1 +/- 0.2 mcg.kg-1.min-1). Norepinephrine was the only vasoactive agent used in these patients. MEASUREMENTS AND RESULTS: A modified Swan-Ganz catheter mounted with a fast response thermistor was inserted in each patient, allowing repeated measurements of RVEDVI and RVEF. At time of inclusion to the study, all but one patient had elevated MPAP (23 +/- 4 mmHg) and RVEF < or = 50%, and all patients had RVEDVI > or = 90 ml.m-2. During norepinephrine infusion, MAP increased from 51 +/- 9 to 89 +/- 10 mmHg (p < 0.0001), PVRI increased from 204 +/- 35 to 286 +/- 63 dynes.s.cm-5.m-2 (p < 0.05), and despite this increase in right ventricular afterload, no detrimental effect in RVEF (36 +/- 11 to 36 +/- 10%) or in RVEDVI (116 +/- 30 to 127 +/- 40 ml.m-2) was observed. A Frank-Starling relationship for the right ventricle was constructed by plotting an index of ventricular performance (RVSWI) against an index of ventricular preload (RVEDVI). A significant upward shift to the right of the relationship was observed during norepinephrine infusion. CONCLUSION: It was concluded that norepinephrine exerted a favourable effect on right ventricular function.     

Size-based characterization by the coupling of capillary electrophoresis to Taylor dispersion analysis

In this work, a new methodology is presented for performing capillary electrophoresis (CE) coupled to Taylor dispersion analysis (TDA). The CE step allows the separation of the different compounds of the injected mixture, while the diffusion coefficient related to each sample zone can be derived from the subsequent TDA step. TDA is an absolute and straightforward nonseparative method allowing the determination of the diffusion coefficient (or hydrodynamic radius) from the peak dispersion obtained in an open tube under Poiseuille laminar flow conditions. With a mass concentration sensitive detector, the hydrodynamic radius derived from TDA is a weight average value calculated upon all the molecules present in the sample zone. Since CE can be hardly coupled to light scattering detection for technical reasons (low volumes, short detection path length), TDA represents an interesting alternative for the size characterization, without calibration, of sample mixtures using CE-based separation techniques. The coupling of CE to TDA can be implemented on a commercial CE apparatus.     

Temperature modulation and quadrature detection for selective titration of two-state exchanging reactants

Biological samples exhibit huge molecular diversity over large concentration ranges. Titrating a given compound in such mixtures is often difficult, and innovative strategies emphasizing selectivity are thus demanded. To overcome limitations inherent to thermodynamics, we here present a generic technique where discrimination relies on the dynamics of interaction between the target of interest and a probe introduced in excess. Considering an ensemble of two-state exchanging reactants submitted to temperature modulation, we first demonstrate that the amplitude of the out-of-phase concentration oscillations is maximum for every compound involved in a reaction whose equilibrium constant is equal to unity and whose relaxation time is equal to the inverse of the excitation angular frequency. Taking advantage of this feature, we next devise a highly specific detection protocol and validate it using a microfabricated resistive heater and an epifluorescence microscope, as well as labeled oligonucleotides to model species displaying various dynamic properties. As expected, quantification of a sought for strand is obtained even if interfering reagents are present in similar amounts. Moreover, our approach does not require any separation and is compatible with imaging. It could then benefit some of the numerous binding assays performed every day in life sciences.     

An improved Hoschek intrinsic parametrization

Smoothing a set of points p_i with a B-spline curve is an usual CAGD application, which remains an open problem due to the choice of the parameter values. J. Hoschek proposed one of the first iterative solution called intrinsic parametrization. This idea has been improved several times by introducing different parameter corrections. This paper deals with a new improvement of Hoschek's method providing better results with a higher speed of convergence. Examples are proposed and compared with the different approaches.     

The human lysyl oxidase-related gene (LOXL2) maps between markers D8S280 and D8S278 on chromosome 8p21.2-p21.3

OBJECTIVE: bcl-2 is a protein which prohibits programmed cell death. The purpose of this study was to determine whether bcl-2 staining was related to traditional prognostic factors and/or recurrence in patients with endometrial carcinoma. METHODS: One hundred twenty consecutively surgically treated patients with endometrial carcinoma had their tumors studied immunohistochemically for bcl-2 staining. RESULTS: The mean follow-up of the patients was 53 months with a median of 56 months (range 30 to 68 months). bcl-2 staining was positive in 44.0% of patients with endometrioid carcinomas and in 23. 1% of patients with nonendometrioid carcinomas (P < 0.001). Increasing depth of invasion (P = 0.014), grade (P = 0.011), and FIGO stage (P = 0.018) were each correlated with decreasing bcl-2 staining. bcl-2 staining was positive in 44.1% of patients whose tumors showed no lymphovascular space invasion and in 11.1% of patients with lymphovascular space invasion (P < 0.001). Only 1 of 26 patients with recurrent disease had persistence of bcl-2 staining. Multivariate analysis revealed FIGO stage (P = 0.0051), histologic grade (P = 0.050), and lack of staining for bcl-2 (P = 0.012) to be independent predictors of recurrence. CONCLUSION: bcl-2 persistence is more common in endometrioid than in nonendometrioid adenocarcinomas of the endometrium. It appears to be inversely correlated with the universally recognized prognostic factors of depth of invasion, histologic grade, and FIGO stage. Lack of bcl-2 persistence was an independent predictor of recurrence of disease. This group of patients continues to be followed to determine the role of bcl-2 persistence or lack of persistence as a predictor of 5-year survival of patients with endometrial carcinoma.     

Effects of intravenous immunoglobulins in thrombopenia related to septic shock

OBJECTIVES: Intravenous immunoglobulins have been shown to be effective in the treatment of immunologically mediated thrombocytopenia. Several articles have been published on the positive effect of immunoglobulins in sepsis-related death. We retrospectively studied the effects of intravenous immunoglobulins used during septic shock thrombocytopenia over a 5-year period in a polyvalent intensive care unit. PATIENTS AND METHODS: Inclusion criteria were development of acute thrombocytopenia under 75 G/l during septic shock, excluding all cases of disseminated intravascular coagulation. Thirty-five patients were included in the study; 18 were given polyvalent intravenous immunoglobulins (group IgIV) and 17 were not (controls). The two groups were comparable for SAPS and APACHE II gravity scores at admission and at day 0 (first day of septic shock with platelet count under 75 G/l), age, sex, platelet count at admission, OSF score, type of referral unit, McCabe score, and the presence of 4 parameters which might affect platelet count hemofiltration, ARDS, surgery, Swan-Ganz catheter. RESULTS: Platelet counts increased on day 8 in the treatment group (63.5 G/l, range 25-453 versus 105.7 G/l, range 38-355; p = 0.0505). The number of days with thrombocytopenia was the same in both groups. Overall mortality was high (60%) but there was a difference between the two groups in favor of the treated group (74.7% versus 44.4%; p = 0.053). The number of red cell units (214 vs. 164) and plasma units (175 vs. 54) transfused was higher in the control group. Platelet transfusion was equivalent in the two groups. DISCUSSION: Although we were unable to demonstrate a significant difference in the effects of immunoglobulins on platelet level and mortality, the trend during this evaluation was comparable with that reported in the literature. For transfusion, and although the results were not significant, a notion of reduced risk was evident. Prospective trials are needed to confirm these observations.     

Conformational changes of the yeast mitochondrial adenosine diphosphate/adenosine triphosphate carrier studied through its intrinsic fluorescence. 1. Tryptophanyl residues of the carrier can be mutated without impairing protein activity

During the transport process the mitochondrial adenine nucleotide carrier (Ancp) undergoes conformational changes which result in modifications of the intrinsic fluorescence of the carrier. To further study these changes by a fluorometric approach, the three tryptophanyl residues (Trp87, Trp126, and Trp235) of the Saccharomyces cerevisiae Anc2p were individually mutated to their tyrosine counterparts. The resulting mutated genes (two-Trp, one-Trp or Trp-less variants) were integrated at the ANC2 locus. A prerequisite for such studies is that all the engineered carrier molecules are still able to catalyze ADP/ATP exchange. The cellular characteristics of the strains expressing the mutated Anc2p and the biochemical properties of the variant Anc2p in mitochondria were examined. Although Trp87 is absolutely conserved in all 30 available Ancp sequences, none of the tryptophanyl residues is essential to the carrier protein folding and the transport activity. The mutated and wild-type Anc2p were expressed to the same level, as evidenced by both ligand binding and immunochemical analyses. When isolated in the presence of detergent, all the variant Anc2p preparations contained ergosterol in similar amounts (9 mol/mol of 35 kDa Anc2p) but no specific interaction was revealed. Our results show that the tryptophanmutated Anc2p are suitable for fluorescence studies, which are reported in the accompanying paper by Roux et al. [(1996) Biochemistry 35, 16125-16131].