Delta HT Research Articles

Prognostic Significance of Stroke-Associated Infection and other Readily Available Parameters in Acute Ischemic Stroke Treated by Intravenous Thrombolysis

ObjectivesThe impact of contracting stroke-associate infection (SAI) that requires antibiotic treatment after an acute ischemic stroke (AIS) treated with alteplase remains unclear. We studied the profiles of SAI in patients with AIS treated with alteplase toward identifying predictive factors and prognostic implications at 90 days post-stroke. MethodsWe analyzed 33 parameters readily available within 24 hours after AIS: demographics, risk factors, and several clinical and biochemical parameters. Outcome measures were mRS ≤ 2 and mortality 90 days post-stroke. Results83 (23.6%) of 352 patients developed SAI. Multivariate logistic regression analysis showed that atrial fibrillation, mRS above 0 pre-stroke, lower delta NIHSS (the difference between NIHSS score measured upon admission and 24 hours after later), CRP≥10 mg/L, and elevated WBC count affected SAI risk (model including CRP levels and WBC count) and atrial fibrillation, mRS above 0 pre-stroke, lower delta NIHSS, HT, and elevated fibrinogen levels affected SAI risk (model excluding CRP levels and WBC count). 231 patients (74.1%) had mRS ≤ 2 at day 90. Multivariate logistic regression analysis showed that younger age, no hypertension, mRS=0 pre-stroke, higher delta NIHSS, no HT, no SAI, and CRP<10 mg/L, were associated with mRS≤2 at day 90. 54 (15.3%) patients died within 90 days. Multivariate logistic regression analysis showed that pre-stroke mRS>0, lower delta NIHSS, HT, CRP≥10 mg/L, lower triglyceride levels affected the risk of death within 90 days. ConclusionsSeveral markers available within 24 hours post-stroke were predictive of SAI that requires antibiotic treatment. SAI affects long-term outcome but not mortality.

Intérêt de l’utilisation d’un sac de recueil dans le diagnostic des hémorragies de la délivrance

Depending on the country and the publications, post-partum hemorrhage (PPH) is either the first or second cause of maternal death in the world, including in developed countries. It remains a significant source of morbidity, severe anemia, blood transfusion, transfusion complications, acquired coagulation disorders and hemostasis hysterectomy. Visual assessment underestimates the amount of blood loss in around 45% of cases. Emergency treatment is therefore sometimes undertaken with some delay, giving time for Disseminated Intravascular Coagulation (DIC) to occur, which worsens the prognosis. A collecting plastic bag put under the pelvis of the mother just after delivery is a quantitative and objective method of measuring blood loss. The objective was to assess sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), studying correlation between bag's volume and hemoglobin and hematocrit variation. Included outpatients were women with unique pregnancy at term. Breech presentations were excluded. We measured serum hemoglobin and hematocrit just after admission for labor. A collecting bag, placed under the pelvis of each woman just after birth, was weighted after delivery. Serum hemoglobin and hematocrit were again assessed at three days. Post-partum hemorrhage was defined by a fall of hematocrit more than 10 points (delta Ht), or by a fall of hemoglobin more than 3g/dL (delta Hb). From January 2003 to May 2003, 272 patients were included. 8.9% of the results were unuseful (n=24). The mean volume of blood loss was 190 ml (5th p=29 ml, 10th p=48 ml, 90th p=610 ml, 95th p=824 ml). The mean delta Ht was 2.7 +/- 4 pts (16.5 / -4.8). The mean delta Hb was 1.2 +/- 1.4 g/dL (5.9 / -1.5). For a delta Ht=10 the calculated bag volume was 564 ml. With this cut off we noted 5.5% PPH (n=15) prevalence=0.06. Sensitivity=34.21%. Specificity=99%. PPV=86%. NPV=90.38%. For a delta Hb=3 the calculated bag volume was 486 ml. With this cut off we noted 10.7% PPH (n=24) prevalence of PPH=0.1. Sensitivity=38.77%. Specificity=95.96%, PPV=67. 85%. NPV=87.7%. The collecting pelvis bag is a rapid and precise procedure to diagnose PPH in the delivery room. It also enables a visual and quantitative non-subjective estimation of blood loss. Because of its simplicity and very low cost, the collecting pelvis bag should be used widely as a routine preventive measure.

Reactivity of Pb(II) at the Mn(III,IV) (oxyhydr)oxide--water interface.

In this study, the reactivity of lead (Pb(II)) on naturally occurring Mn(III,IV) (oxyhydr)oxide minerals was evaluated using kinetic, thermodynamic, and spectroscopic investigations. Aqueous Pb(II) was more strongly adsorbed to birnessite (delta-MnO1.7) than to manganite (gamma-MnOOH) under all experimental conditions. The isoteric heat of Pb adsorption (delta HT) or birnessite was 94 kJ mol-1 at a surface loading of 1.1 mmol g-1, and decreased with increasing adsorption density. This indicated that adsorption was an endothermic process and that birnessite possessed heterogeneous sites of reactivity for Pb. X-ray absorption fine structure (XAFS) spectra revealed that Pb was adsorbed as inner-sphere complexes on both birnessite and manganite with no evidence to suggest oxidation as an operative sorption mechanism. Lead appeared to coordinate to vacancy sites in the birnessite layer structure with concurrent release of Mn to solution, which resulted in a greater number of second shell Mn scatterers in Pb-birnessite when compared to Pb-manganite samples. The difference in Pb coordination apparently explained the contrasting desorption behavior between the two Mn minerals. These results have significant implications for Pb partitioning in soil environments containing solid-phase Mn(III,IV) (oxyhydr)oxides.

Dynamical entropy is conserved during cocaine-induced changes in fetal rat motor patterns.

Our previous studies demonstrated that the intra-cisternal (IC) administration of cocaine to fetal rats increased motor activity and decreased responsiveness to perioral stimulation. One explanation for these observations comes from the behavioral pharmacology of stimulant drugs: increased motor activity is often associated with a decrease in its variety. Previous power spectral transformation of this data suggests an alternative explanation: cocaine-induced hyperactivity fixates a new behavioral pattern with complexity equal to that of saline controls. We explore these possibilities using statistical techniques derived from studies of nonlinear dynamical systems, examining patterns of the total motor activity of the individual fetus as counts per 5 s interval on either gestational day E20 or E21 for 20 min following IC injections of saline, 2.5 or 10 mg/kg of cocaine. The results are consistent with a state in which increased spontaneous activity is associated with the emergence of a new dynamical pattern which conserves entropy and provides experimental support for a fundamental conservation-variational relation, hT approximately equal to lambda 1 x DR, that has been proven for abstract models of chaotic dynamical systems. A multivariate analysis of variance (MANOVA) followed by appropriate analyses of variance (ANOVAs) and pairwise comparisons revealed that, whereas cocaine induced increases in the total amount of motor activity, the rate of increase in the variety of new sequences in activity counts over time did not change with treatment and age conditions. This invariant is quantified by an absence of change in topological entropy, delta hT = 0. The analyses also showed that, in order to maintain hT values, compensatory changes took place in the leading Lyapounov characteristic exponent, lambda 1 (the distance between sequential values 'stretched' along the increasing amplitudes of the variations) such that delta lambda 1 > 0, and the correlation dimension, DR (the hierarchical range of possible values, 'complicated clustering') was reduced, so that delta DR < 0. Our findings are consistent with the idea that the association between cocaine-induced increases in activity and decreases in adaptive response are not due to the dynamical entropy loss of decreased behavioral variety, but are rather the result of competitive interference by a drug-induced, equally complex, new pattern of spontaneous behavior.

Change in haemoglobin concentration, haematocrit and vasoactive hormones in haemodialysis patients with erythropoietin-associated hypertension.

The changes in haemoglobin concentration, haematocrit, plasma renin activity (PRA) and atrial natriuretic peptide (ANP) were studied in 10 haemodialysis patients with erythropoietin-associated hypertension. All patients received intravenously 1500 IU of recombinant human erythropoietin (rHuEPO) thrice weekly for 24 weeks. Treatment with rHuEPO induced significant rises in haemoglobin concentration (p < 0.001) and haematocrit (p < 0.01). However, the difference between post- and pretreatment levels of haemoglobin (delta Hb) was not correlated with that between post- and pre-treatment mean blood pressure (delta MBP). No correlation was found between delta Ht (difference between post- and pre-treatment values of haematocrit) and delta MBP. These results indicate that elevation of the haematocrit and haemoglobin concentration of haemodialysis patients does not necessarily lead to an increase in blood pressure. In these patients, no significant differences were observed in PRA and ANP, comparing pre-treatment values with those measured 4, 8, 12 or 24 weeks after commencing rHuEPO. This suggests that neither PRA nor ANP play a central role in the pathogenesis of rHuEPO-induced hypertension.

DNA relatedness among some thermophilic members of the genus Methanobacterium: emendation of the species Methanobacterium thermoautotrophicum and rejection of Methanobacterium thermoformicicum as a synonym of Methanobacterium thermoautotrophicum.

DNA reassociation was used to determine levels of relatedness among four thermophilic Methanobacterium strains that are able to use formate and between these organisms and two representative strains of Methanobacterium thermoautotrophicum, strain delta HT (= DSM 1053T = ATCC 29096T) (T = type strain) and strain Marburg (= DSM 2133). Three homology groups were delineated, and these groups coincided with the clusters identified by antigenic fingerprinting. The first group, which had levels of cross hybridization that ranged from 73 to 99%, included M. thermoautotrophicum delta HT, Methanobacterium thermoformicicum Z-245, Methanobacterium sp. strain THF, and Methanobacterium sp. strain FTF. The second and third groups were each represented by only one strain, Methanobacterium sp. strain CB-12 and M. thermoautotrophicum Marburg, respectively (cross-hybridization levels, 13 to 30 and 29 to 33%, respectively). Our results indicate that the name M. thermoformicicum should be rejected as it is a synonym of M. thermoautotrophicum. The taxonomic positions of strains Marburg and CB-12 need further investigation.

Gonadotrophin‐Releasing Hormone Agonist Treatment of Central Precocious Puberty: an Analysis of Growth Data in a Developmental Context

Growth and skeletal maturation was assessed in 83 girls with central precocious puberty (CPP) during pituitary-gonadal suppression induced by treatment with a gonadotrophin-releasing hormone agonist (GnRHa). The mean pretreatment chronological age (CA) was 6.3 years and the mean bone age (BA) was 10.6 years. During the suppression of gonadal sex steroid secretion, mean height velocity (HV) decreased from a pretreatment value of 10.8 cm/year to 5.9 (year 1, n = 83), 4.9 (year 2, n = 72), 4.2 (year 3, n = 45), and 4.4 (year 4, n = 23) cm/year. During each interval, there was a negative correlation between HV and the pretreatment BA. In addition, the rate of skeletal maturation was reduced during GnRHa treatment (delta BA/delta CA = 0.6 +/- 0.1 over 3 years, n = 45). The rate of skeletal maturation during therapy was also negatively correlated with pretreatment BA. Predicted adult stature, based upon zeta-scores of height for BA, increased significantly and progressively during therapy but the changes in height SDS for BA varied significantly. Since HV, delta BA/delta CA, and the change in height SDS for BA (delta HT SDS for BA) during pituitary-gonadal suppression all correlated with the initial degree of skeletal maturation, the effect of GnRHa therapy on final adult height in children with CPP will be best understood if growth data are assessed within a developmental framework.

Raman study of NaClO3 as a function of temperature into the melt and the novel high temperature phase

Raman spectra have been measured for oriented single crystals of NaClO3 II from 77 K to the melting temperature, for the molten salt and the high temperature phase, NaClO3 I. The results for NaClO3 II were in excellent agreement with unit-cell group analysis. Apparent anomalies associated with the presence of weak bands due to naturally abundant 37Cl and 18O substituted ions have been accounted for on the basis of intermolecular coupling models. The unusual high temperature, ambient pressure phase transition for NaClO3 has been characterised by spectroscopic and thermal methods. The novel feature about the high temperature phase is the fact that it may only be reached by cooling the melt and it transforms back to the room temperature phase at about 510 K as the sample is cooled. The longitudinal optical mode at about 1030 cm-1 which was characteristic of the acentric room temperature phase (P213, T4) was conspicuously absent in the Raman spectrum of the high temperature phase. The Raman spectrum of the high temperature phase indicated that the crystal has a centric structure but the similarity of many bands with the spectrum of the room temperature phase suggested that the phase transition involved only small changes in atomic positions. The structure remained ordered but there was evidence of considerable band broadening due to increased thermal motion. The Raman results are consistent with the diffraction studies of Meyer and Gasperin (1973) who reported a monoclinic structure similar to room temperature KClO3, space group P21/a. Measurements of the heats of fusion and transition by differential scanning calorimetry gave values of Delta Hf=21.7 kJ mol-1, Delta Sf=40.6 J mol-1, Delta Ht=4.1 kJ mol-1, Delta St=8.2 J mol-1 K-1. The relatively small values of the heat and entropy of transition compared to those of fusion also indicated that the high temperature phase was not disordered.

The nature of the hydrophobic binding of small peptides at the bilayer interface: implications for the insertion of transbilayer helices.

One method of obtaining useful information about the physical chemistry of peptide/bilayer interactions is to relate thermodynamic parameters of the interactions to structural parameters obtained by diffraction methods. We report here the results of the application of this approach to interactions of hydrophobic tripeptides of the form Ala-X-Ala-O-tert-butyl with lipid bilayers. The thermodynamic constants (delta Gt, delta Ht, and delta St) for the transfer of the tripeptides from water into DMPC vesicles were determined for X = Leu, Phe, and Trp and found to be consistent with those expected for hydrophobic interactions above the phase transition of DMPC. Combining these results with the earlier ones of Jacobs and White [(1986) Biochemistry 25, 2605-2612], the favorable free energies of transfer with different amino acids in the -X- position increase in the order Gly less than Ala less than Leu less than Phe less than Trp in agreement with the Nozaki and Tanford [(1971) J. Biol. Chem. 246, 2211-2217] hydrophobicity scale. Determination of the location of Ala-[2H5]Trp-Ala-O-tert-butyl in oriented DOPC bilayers by neutron diffraction shows that the most hydrophobic peptide of the series is confined to the bilayer headgroup/water region. Refinement of the diffraction measurements shows that only 13% of the tryptophan is associated with the hydrocarbon core. The distribution of the water tends to mirror that of the peptide. Unlike peptide-free bilayers, 5% of the water penetrates the hydrocarbon, which is about 100-fold greater than expected. A quantitative thermodynamic analysis of the interfacial binding of the peptides suggests that (1) the hydrophobic interactions are 60-70% complete upon binding at the bilayer interface, (2) the interface is likely to play an important role in helix formation and insertion, (3) the hydrogen bond status of amino acid side chains is crucial to insertion, and (4) an a priori lack of knowledge of the status of such bonds could limit the precision of hydrophobicity plots. We introduce an interfacial hydrophobicity scale, IFH(h), with a variable hydrogen bond parameter (h) that permits one to consider explicitly hydrogen bonding in transbilayer helix searches.

Growth and endocrine function in steroid sensitive nephrotic syndrome.

Longitudinal height data and physical development were assessed in 29 boys and 12 girls taking long term steroid treatment for steroid sensitive nephrotic syndrome. Growth in both boys and girls, assessed by changes in height standard deviation score (delta Ht SDS), worsened significantly with chronological age. There was a significant negative correlation between delta Ht SDS and duration of treatment in boys, but not in girls. There was no correlation between delta Ht SDS and relapse rate or the use of cyclophosphamide. In the boys, Ht SDS decreased significantly only after the age of 10 years and was associated with delay in the appearance of secondary sexual characteristics. Eight adolescent boys were assessed endocrinologically by an overnight hormone profile. Blunting of the pulsatility of growth hormone and gonadotrophins was seen in six. Normal profiles were seen in two subjects who were both off steroid treatment at the time of study. Abnormal endocrine function in adolescent boys treated long term for steroid sensitive nephrotic syndrome corresponded with the clinical picture of delayed onset of puberty, which accounted for severe growth retardation in a substantial proportion of subjects.

A comparative calorimetric study on tRNA unfolding.

The heat effects involved in thermal unfolding of five tRNAs with different primary structures have been determined by direct differential scanning microcalorimetry. The overall molar values of the transition enthalpy (delta Ht) are 1150 kJ/mol for tRNA Lys2 (yeast), 1250 kJ/mol for tRNA Phe (yeast), 1350 kJ/mol for tRNA Val (yeast), 1490 kJ/mol for tRNA Val (E. coli) and 1630 kJ/mol for tRNA Tyr (E. coli). The tRNAs differ in their melting behaviour as can be shown by a comparison of the calorimetric curves. The calorimetrically measured delta Ht values are about 350 kJ/mol higher than the transition enthalpy values for the cloverleaf arrangement, which were estimated using the known parameters for G.C and A.U base pairs.

Calorimetric Studies on Melting of tRNAPhe (Yeast)

The heat effects involved in thermal unfolding of tRNAPhe from yeast have been determined in various buffer systems by direct differential scanning calorimetry. Perfect reversibility of the melting process has been demonstrated for measurements in the absence of Mg2+ ions. The overall molar transition enthalpy, delta Ht = 298 +/- 15 kcal mol-1 (1247 +/- 63 kJ mol-1), has been shown to be independent of the NaCl concentration and the nature of the buffers used in this study. Delta Ht is identical in the presence and in the absence of Mg2+ ions within the margin of experimental error. This experimental result implies a vanishing or very small heat capacity change to be associated with melting. Decomposition of the calorimetrically determined complex transition curves, on the assumption that the experimental melting profile represents the sum of independent two-state transitions, results in five transitions which have been assigned to melting of different structural domains of the tRNA.