Short DT Research Articles

Metastasis-directed ablative radiotherapy in castrate-resistant oligometastatic prostate cancer: A retrospective study of 8 high-volume French centers from the COLib (Cercle des Oncologues Libéraux).

152 Background: In castrate-resistant oligo metastatic prostate Cancer (CRoligoMPC), the benefit of metastases-directed ablative radiotherapy (MDRT) is poorly investigated. Our study retrospectively reviewed the cases of CR oligoMPC treated with MDRT. Methods: Patients receiving MDRT in CRoligoMPC were retrospectively reviewed. Patients were included if: they had < 5 metastases on metabolic work-up, testosterone is < 50 ng/mL, metastases received MDRT. Patients and disease's data were collected: age, Gleason score, time to metastases, time to castration resistance; medical treatments, metastases location (bone versus node); radiotherapy regimens, PSA (PSA doubling time PSADT at the time of MDRT and PSA response). Progression was assessed according to PCWG criteria. PFS and OS are defined as the time from MDRT to first progression, for PFS and death date for OS. Kaplan-Meier analysis was used to summarize time-to-event variables and curves were compared with the log-rank test. A logistic regression was used to identify predictive factors of PFS. Results: the median follow up is 25.6 months.107 patients met inclusion criteria, among those 197 metastases received MDRT. Median age at MDRT time was 73 years. Median hormonosensitivity duration was 38 months (4-225). Forty six patients had metastases at the time of hormonosensitivity and 61 developed metastases in the castration resistance (CR)period (spartan-like population). PSA doubling time at the time of MDT RT was < 12 months in 88%. A median number of 2 metastases per patient was treated (1-4), 54% had RT on bony metastases only, 38% on nodes, 8% on bone + node. In 61 patients with metastases at the time of CRPC, 34.5% received a CR systemic medication before or concomitantly to MDRT, 39% received CR medication at progression, 23.5% never received CR treatment (unknown in 3%). OS is 93% at 2 years and 81.4% at 3 years. For node-only metastases, 2y OS is 100% versus 89% for bone metastases. Median PFS is 12.6 months (IC 95% [9.6; 17]). Metastases location, grade group, PSA or hormonosensitivity duration were not related to PFS in a univariate survival analysis. PFS was 10.2 months when PSA Doubling time was < 6 months, versus 18.2 months when it exceeded 6 months (NS). The PSA 50% response was studied in the Spartan like population, it was 83.4% in patients receiving MDRT AND new generation hormonotherapy; 31% in those who received MDRT without new generation hormonotherapy, and 20% in those who received MDRT at the time of progression of oligometastases occurring under new generation hormonotherapy. Conclusions: In a population of CR oligoM PC with short PSA DT, MDRT leads to a PFS of 12.6 months and to a 3y OS of 81.4%. In this setting, androgen receptor targeting agents are the standard of care. Whether adding MDRT could improve prognosis should be prospectively evaluated.

Interactive effects of conservation tillage on the aggregate stability and soil organic carbon

AbstractBackgroundSoil carbon sequestration is of great significance to achieve carbon neutralization at an early date.AimsThe present study was conducted in order to explore the interactive effects of conservation tillage on soil organic carbon (SOC) and aggregate stability, and to understand the response of soil organic carbon to aggregate structure and distribution characteristics.MethodsUndisturbed soil from varying depths was collected from the conservation tillage demonstration base under differential tillage practices (NT, no‐tillage mulch; DT, deep‐tillage mulch; CT, conventional‐tillage mulch). SOC and stable‐aggregates of different particle sizes, their number, and structures were analyzed and the relationship between the stability of soil aggregates and SOC was presented.ResultsThe SOC content was the highest under CT treatment (1.67 g kg–1) and the lowest under NT treatment (1.31 g kg–1). In surface soil, the number of macroaggregates (>0.25 mm, M) under NT treatment was the largest (89.1%), the mean weight diameter (MWD) and geometric mean diameter (GMD) of water stability and mechanical aggregates were the highest, and the fractal dimension (D) was the lowest. This indicated that the NT treatment could maintain the aggregate structure of surface soil well. In the short term, DT and CT could increase SOC content, while NT could decrease SOC content. There was a significant correlation between SOC content and MWD (R2 = 0.40), GMD (R2 = 0.38), and D (R2 = 0.44). The more stable the aggregate structure, the higher the soil fixation and maintenance of SOC.ConclusionsSOC content and aggregate stability have a synergistic effect, and NT can promote the formation of soil aggregates, improve their stability, and balance the distribution of carbon in soil aggregates with different particle sizes.

Évaluation par l’échocardiographie des pressions de remplissage chez des patients hypertendus en insuffisance cardiaque à fraction d’éjection préservée dans une unité Nord Africaine d’hôpital de jour

ObjectiveTo assess the left ventricular (LV) filling pressures by Doppler Tissulaire Imaging (DTI) in the management of hypertensive patients with heart failure and preserved systolic function (HF-PEF) in our outpatient clinic. To involve the patient on the basis of their clinical, biological and echocardiography data, in identifying the risk factors that need change. Patients and methodsFrom 2004 to 2014, heart failure with preserved systolic function (HF-PEF) has been diagnosed in 200 consecutive hypertensive patients (pts) at our Algerian outpatient unit. Data were collected on blood pressure at the time of the examination, body mass index (BMI), waist, comorbid conditions including dyslipidemia, diabetes and atrial fibrillation (AF). LV ejection fraction>50 % is taken as the including criteria with acquisition as described in the Chamber Quantification update. Left ventricular global systolic function by biplane disk summation Simpson method and diastolic function is assessed by the mitral inflow measurements regarding recommendations for the evaluation of left ventricular diastolic function by echocardiography from the European Association of Cardiovascular Imaging (EACVI) and the American Society of Echocardiography (ASE). ResultsMean age was 65±11 yrs; 66 % were female; waist circumference in men>102cm and in women>88cm was found in 82 % of the pts and 50 % were diabetics. Body weight (BMI)>30kg/m2 is depicted in 88 (44 %). Dyslipidemia is depicted in 78 pts (39 %). Ischemic heart disease was diagnosed in 64 pts (32 %); history of thromboembolic event in 78 pts (39 %); valvular disease in 40 pts (20 %). ECG showed AF in 60 pts (30 %), complete left bundle branch block (LBBB) in 20 pts (10 %). The echographic findings were as follow: left ventricular hypertrophy (LVH) in 126 pts (63 %) and left atrial (LA) enlargement in 111 pts (55 %). Mean left ventricular ejection fraction (LVEF) is about 55±10 %. Delayed relaxation (Em/Am<1) and deceleration time>150ms (DT) in 80 pts (40 %), of them, 56 had increased filling pressures (Em/Ea>8 and Ap>Am); pseudo-normal patterns (1<Em/Am<2 and DT<150ms) in 80 pts (40 %); restrictive filling pattern (Em/Am≥2) and short DT<100ms in 40 pts (20 %). ConclusionsThe hypertensive pts referred for an echo examination are often diabetics and frequently demonstrate preserved left ventricular function with increased filling pressures. This is useful for managing their treatments in the context of a cardiac rehabilitation programme.

P1-07: The use of echocardiography left ventricular filling pressures in hypertensive patients with heart failure and preserved systolic function in an North Africa unit day

OBJECTIVE To assess the left ventricular (LV) filling pressures by Doppler Tissulaire Imaging (DTI) in the management of hypertensive patients with heart failure and preserved systolic function (HF-PEF) in our outpatient clinic. To involve the patient on the basis of their clinical, biological and echocardiography data, in identifying the risk factors that need change. PATIENTS AND METHODS From 2004 to 2014, heart failure with preserved systolic function (HF-PEF) has been diagnosed in 200 consecutive hypertensive patients (pts) at our Algerian outpatient unit. Data were collected on blood pressure at the time of the examination, body mass index (BMI), waist, comorbid conditions including dyslipidemia, diabetes and atrial fibrillation (AF). LV ejection fraction>50 % is taken as the including criteria with acquisition as described in the Chamber Quantification update. Left ventricular global systolic function by biplane disk summation Simpson method and diastolic function is assessed by the mitral inflow measurements regarding recommendations for the evaluation of left ventricular diastolic function by echocardiography from the European Association of Cardiovascular Imaging (EACVI) and the American Society of Echocardiography (ASE). RESULTS Mean age was 65±11 yrs; 66 % were female; waist circumference in men>102cm and in women>88cm was found in 82 % of the pts and 50 % were diabetics. Body weight (BMI)>30kg/m(2) is depicted in 88 (44 %). Dyslipidemia is depicted in 78 pts (39 %). Ischemic heart disease was diagnosed in 64 pts (32 %); history of thromboembolic event in 78 pts (39 %); valvular disease in 40 pts (20 %). ECG showed AF in 60 pts (30 %), complete left bundle branch block (LBBB) in 20 pts (10 %). The echographic findings were as follow: left ventricular hypertrophy (LVH) in 126 pts (63 %) and left atrial (LA) enlargement in 111 pts (55 %). Mean left ventricular ejection fraction (LVEF) is about 55±10 %. Delayed relaxation (Em/Am 150ms (DT) in 80 pts (40 %), of them, 56 had increased filling pressures (Em/Ea>8 and Ap>Am); pseudo-normal patterns (1<Em/Am<2 and DT<150ms) in 80 pts (40 %); restrictive filling pattern (Em/Am≥2) and short DT<100ms in 40 pts (20 %). CONCLUSIONS The hypertensive pts referred for an echo examination are often diabetics and frequently demonstrate preserved left ventricular function with increased filling pressures. This is useful for managing their treatments in the context of a cardiac rehabilitation programme.

Effect of the settings of two automatic cluster removers (ACRs) on the milking efficiency of Manchega ewes

The implementation of automatic vacuum cutting devices (AVCDs, component of the ACRs, automatic cluster removers) represents one of the most recent advances in small ruminant milking machines. However, there is a lack of scientific studies regarding optimal settings (milk flow threshold, MF, and delay time, DT) for the milking of Manchega ewes. The aim of this study was to assess the effect of different combinations of operating parameters of two AVCDs (LactoFlow®-Dematron® of GeaFarm Technologies® and SG®-mm25® of DeLaval®) on milking efficiency (milking time and milk fractioning), milking routine (cluster falls and double cluster attachment) and mean vacuum drops. Two tests were performed including several latin square design experiments. Regarding LactoFlow®-Dematron® installed in a low-line milking machine, four MF (100, 150, 200 and 250g/min) were combined with three DT (10, 15 and 20s) employing 45 ewes on a research farm and regarding SG®-mm25® installed in high-line milking machine, two MF (150 and 200g/min) were combined with three DT (10, 15 and 20s) employing 54 ewes on a commercial farm. According to the results, regarding Dematron®-Lactoflow®, it was appreciable that the employment of MF 100g/min increased milking duration without improving the milk fractioning and the employment of MF 250g/min did not reduce milking duration. The minimum differences between MF 150 and 200g/min showed in this test suggest that these levels would be located within the optimal setting of this AVCD. On the other hand, regarding SG®-mm25®, two strategies could be considered, the use of MF 150g/min combined with high DT to extract the maximum amount of milk or the use of MF 200g/min combined with short DT to optimize the time employed. Regarding milking routine, no differences were found in any of the test. The increase of both MF and DT showed higher values of mean vacuum drops in the two tests performed.Further studies are needed to study how AVCD affects the milking time of the total herd, production and composition of the milk and the sanitary status of the mammary gland of Manchega breed ewes.

DESIGN AND DEVELOPMENT OF ZIPRASIDONE FAST DISSOLVING TABLETS BY VACUUM DRYING TECHNIQUE

The objective of this research was to formulate fast dissolving tablet of Ziprasidone for rapid action. Vacuum drying method was adapted to prepare the tablets by using two different Sublimating agents. All formulations are evaluated for pre and post-compression parameters like Angle of repose, Bulk density, Tapped density, Housners ratio, Hardness, Weight variation, wetting time, water absorption ratio, Disintegration time, Drug content. The results obtained showed that the quantity of camphor significantly affect response variables. The results indicate that the optimized tablet formulation provides a short DT of 13 sec with sufficient crushing strength and acceptable friability.

Imatinib Dose Interruption in Responding CML Patients Is Associated with Characteristic BCR-ABL Kinetics, Which Could Help to Differentiate Non-Adherence From Drug Resistance

Imatinib Dose Interruption in Responding CML Patients Is Associated with Characteristic BCR-ABL Kinetics, Which Could Help to Differentiate Non-Adherence From Drug Resistance

Long-Term Hormonal Therapy: Who Would Benefit?

Traditionally, the role of hormonal therapy (HT) for prostate cancer (PCa) has been the palliative treatment of advanced and metastatic disease. Recently, advances in the development of androgen-deprivation therapy (ADT) with luteinising hormone-releasing hormone (LHRH) agonists have made LHRH agonists the standard of care for 90% of men with advanced or metastatic PCa. Although the role of ADT is historically well defined, recent studies demonstrate that the treatment of advanced or metastatic PCa with ADT can be tailored to the needs of the patient. This may be achieved by the immediate or deferred initiation of ADT (orchiectomy or LHRH agonist treatment) depending upon the nature of the disease and the patient's age. Patients who are likely to die of non-PCa-related causes prior to an indication for treatment initiation, for example, may benefit from deferred treatment, which may spare them the burden of treatment-related adverse events. In contrast, patients who are likely to die of PCa-related causes may benefit from immediate treatment because this option may delay disease progression and reduce symptom burden. Additionally, recent studies have shown that prognostic disease markers such as prostate-specific antigen (PSA) and PSA doubling time (PSA DT) can be used as indicators of who may receive the greatest benefit from treatment. Patients with a high baseline PSA level or a short PSA DT (markers of aggressive and/or advanced disease), for example, are more likely to die of disease-related causes than patients with low baseline PSA levels or long PSA DT. Furthermore, recent studies have shown that HT may be used successfully in adjuvant settings for patients in earlier stages of the disease and/or who require radical treatment. This paper reviews which patients can benefit from HT in terms of treatment timing, baseline prognostic indicators, disease stage, and adjuvant use.

Role of Chemotherapy in Nonmetastatic Hormone-Refractory Prostate Cancer

Abstract Context Docetaxel chemotherapy has become the standard first-line treatment for metastatic hormone-refractory prostate cancer (HRPC). Nowadays, one of the goals of research is to determine optimal management strategies for different patient populations with prostate cancer. Objective Because the utility of docetaxel in patients with nonmetastatic HRPC has not yet been evaluated, one of the most challenging questions is to define the role of chemotherapy in nonmetastatic HRPC. Evidence acquisition In a recently published subset analysis of TAX-327, a multivariate prognostic model incorporating prostate-specific antigen (PSA) kinetics has been developed to predict survival at 1, 2, and 5 yr in men with metastatic HRPC treated with chemotherapy. This novel model includes PSA doubling time (PSA DT), baseline pain, baseline PSA level, age, type of progression at baseline (measurable disease or bone scan compared with PSA only), presence of liver metastases, and the number of metastatic disease sites. Evidence synthesis The authors found a statistically significantly better overall survival in patients with PSA ≤114 ng/ml and PSA DT >55 d. Patients with a PSA DT of Conclusions Based on these findings, it seems clear nowadays that evaluation of PSA kinetics can help us to delineate the potential benefits of the early indication of chemotherapy. It could be hypothesized that docetaxel-based chemotherapy could have a role in those patients with nonmetastatic HRPC who have a very short PSA DT.

Predicting time to metastatic progression from biochemical recurrence after radical prostatectomy

4642 Background: Many patients with a rising PSA (biochemical recurrence; BCR), after radical prostatectomy (RP) will eventually develop metastases, but our ability to predict the risk of progression over time is limited. We developed a model (nomogram) that incorporates all known prognostic factors to predict the probability of Mets 8 years after BCR. Methods: We queried our multidisciplinary prostate cancer database for patients who developed BCR after RP for clinically localized disease. We defined BCR as 3 subsequent peaks in PSA ≥0.1 ng/ml. After excluding 14 adjuvant radiation patients, we found 816 followed for 0.1 to 15.9 (median 4.3) years after BCR. We recorded times of secondary treatment (radiation or hormonal therapy), metastases and death. A Cox proportional hazards analysis incorporated preoperative PSA, use of neoadjuvant hormonal therapy (NHT), time from surgery to BCR, pathologic findings [surgical margin, presence of extracapsular extention, seminal vesicle invasion (SVI), lymph node metastases, and pathologic Gleason score (GS)], PSA doubling time (PSA DT) and PSA value at BCR into a predictive model. Results: Secondary treatment for BCR only was a frequent event: 216 patients (26.5%) had radiation therapy and 340 (41.7%) hormones; 157 developed metastases, 67 died of other causes and 244 (29.9%) were alive with out metastases or secondary treatment at last follow-up. In the multivariate model the following predicted metastatic progression: high preoperative PSA (P=0.01), use of NHT (P=0.02), presence of SVI (P=0.005), high pathologic GS (P<0.001), short PSA DT (P=0.01) and high PSA value at BCR (P<0.001). A nomogram for predicting risk of metastases at 8 years was constructed with a concordance index of 0.75. Conclusions: Multiple disease factors affect the risk of metastases after BCR. This new nomogram helps predict, at the time of BCR after RP, the 8-year probability of metastases for the individual patient and provides a useful tool to identify patients appropriate for intervention trials or surveillance. No significant financial relationships to disclose.

Predicting time to metastatic progression from biochemical recurrence after radical prostatectomy

4642 Background: Many patients with a rising PSA (biochemical recurrence; BCR), after radical prostatectomy (RP) will eventually develop metastases, but our ability to predict the risk of progression over time is limited. We developed a model (nomogram) that incorporates all known prognostic factors to predict the probability of Mets 8 years after BCR. Methods: We queried our multidisciplinary prostate cancer database for patients who developed BCR after RP for clinically localized disease. We defined BCR as 3 subsequent peaks in PSA ≥0.1 ng/ml. After excluding 14 adjuvant radiation patients, we found 816 followed for 0.1 to 15.9 (median 4.3) years after BCR. We recorded times of secondary treatment (radiation or hormonal therapy), metastases and death. A Cox proportional hazards analysis incorporated preoperative PSA, use of neoadjuvant hormonal therapy (NHT), time from surgery to BCR, pathologic findings [surgical margin, presence of extracapsular extention, seminal vesicle invasion (SVI), lymph node metastases, and pathologic Gleason score (GS)], PSA doubling time (PSA DT) and PSA value at BCR into a predictive model. Results: Secondary treatment for BCR only was a frequent event: 216 patients (26.5%) had radiation therapy and 340 (41.7%) hormones; 157 developed metastases, 67 died of other causes and 244 (29.9%) were alive with out metastases or secondary treatment at last follow-up. In the multivariate model the following predicted metastatic progression: high preoperative PSA (P=0.01), use of NHT (P=0.02), presence of SVI (P=0.005), high pathologic GS (P<0.001), short PSA DT (P=0.01) and high PSA value at BCR (P<0.001). A nomogram for predicting risk of metastases at 8 years was constructed with a concordance index of 0.75. Conclusions: Multiple disease factors affect the risk of metastases after BCR. This new nomogram helps predict, at the time of BCR after RP, the 8-year probability of metastases for the individual patient and provides a useful tool to identify patients appropriate for intervention trials or surveillance. No significant financial relationships to disclose.

The Role of Soluble CD23 in Distinguishing Stable and Progressive Forms of B-chronic Lymphocytic Leukemia

Soluble CD23 (sCD23) has been recognized as an important prognostic parameter in patients with chronic lymphocytic leukemia (B-CLL) at early clinical stages. There is, however, no clear information on its prognostic significance in advanced stages and on its role as an indicator for aggressive or indolent courses of disease. Therefore, sCD23 was measured in the serum of 145 patients at diagnosis and serial determinations were carried out for 8 years in 38 patients. The results indicate that in patients with identical clinical stages at first presentation the disease could take different courses depending on initial sCD23 concentrations below or above specific threshold levels (860 and 5900 U/ml). sCD23 higher than these thresholds was associated with faster progression into upper clinical stages. Furthermore, sCD23-doubling time (sCD23-DT) indicated that patients with long DT progressed slowly, while those with short DT had more aggressive disease. Particularly in patients with advanced disease stages, long sCD23-DT indicated development of smoldering disease. Since sCD23 levels reflect total tumor mass, determination of sCD23-DT has probably a better predictive value than lymphocyte doubling time. It appears that B-CLL patients can be divided into different risk categories according to initial determinations of sCD23 and that sCD23-DT is an additional important parameter in predicting disease progression.

The Importance of Coulombic End Effects: Experimental Characterization of the Effects of Oligonucleotide Flanking Charges on the Strength and Salt Dependence of Oligocation (L 8+) Binding to Single-Stranded DNA Oligomers

Binding constants K obs, expressed per site and evaluated in the limit of zero binding density, are quantified as functions of salt (sodium acetate) concentration for the interactions of the oligopeptide ligand KWK 6NH 2 (designated L 8+, with Z L = 8 charges) with three single-stranded DNA oligomers (ss dT-mers, with | Z D| = 15, 39, and 69 charges). These results provide the first systematic experimental information about the effect of changing | Z D| on the strength and salt dependence of oligocation-oligonucleotide binding interactions. In a comparative study of L 8+ binding to poly dT and to a short dT oligomer (| Z D| = 10), Zhang et al. (1996. Proc. Natl. Acad. Sci. USA. 93:2511–2516) demonstrated the profound thermodynamic effects of phosphate charges that flank isolated nonspecific L 8+ binding sites on DNA. Here we find that both K obs and the magnitude of its power dependence on salt activity (| S a K obs|) increase monotonically with increasing | Z D|. The dependences of K obs and S a K obs on | Z D| are interpreted by introducing a simple two-state thermodynamic model for Coulombic end effects, which accounts for our finding that when L 8+ binds to sufficiently long dT-mers, both Δ G obs o = −RT ln K obs and S a K obs approach the values characteristic of binding to poly-dT as linear functions of the reciprocal of the number of potential oligocation binding sites on the DNA lattice. Analysis of our L 8+-dT-mer binding data in terms of this model indicates that the axial range of the Coulombic end effect for ss DNA extends over ∼10 phosphate charges. We conclude that Coulombic interactions cause an oligocation (with Z L < | Z D|) to bind preferentially to interior rather than terminal binding sites on oligoanionic or polyanionic DNA, and we quantify the strong increase of this preference with decreasing salt concentration. Coulombic end effects must be considered when oligonucleotides are used as models for polyanionic DNA in thermodynamic studies of the binding of charged ligands, including proteins.

Diffusion of beam ions at the Tokamak Fusion Test Reactor

Various DD and DT plasmas are analysed for effects of fast ion transport with a time dependent, 1 1/2 -D transport simulation code (TRANSP). The sensitivity of the simulations to fast ion diffusion modelling is tested against numerous parameters. Strong correlations are found with beam power and plasma stored energy. The neutron emission sensitivity is mostly affected by the fraction of beam-beam neutrons. Wall recycling is essential in interpreting the results for DT plasmas heated with pure deuterium or pure tritium beams. The decay of the 14 MeV neutron emission following a short DT beam pulse implies a small fast ion diffusion coefficient (Df<0.05 m2/s). The agreement of the measured neutron emission and diamagnetic flux with the simulations in DT plasmas heated with various numbers of tritium and deuterium beams, and power, implies that Df<or=0.2 m2/s

Kinetic Parameters of the Translocation of Bacteriophage T4 Gene 41 Protein Helicase on Single-stranded DNA

The bacteriophage T4 gene 41 helicase protein (gp41) carries a single stranded DNA-dependent ATPase activity that is essential to its helicase activity. This ATPase activity can be stimulated by a wide variety of single-stranded DNA cofactors, including homo-oligomers and homopolymers 8 to ∼ 10,000 nucleotide residues in length, and by natural single-stranded DNA, such as bacteriophage M13 DNA. The steady state ATPase activity of gp41 on single-stranded homopolymeric cofactors is dependent on the length of the cofactor, in that the kinetic parameters Vmax and Kact (or KDNAm) have a characteristic length dependence. Vmax values for different DNA lengths show a hyperbolic dependence on DNA length, while Kact values are independent of DNA lengths exceeding ∼ 20 nucleotide residues. Use of the detailed theoretical analysis developed in the preceding paper reveals that: (1) these results support the earlier proposal that gp41 translocates on single-stranded DNA in an ATP dependent manner; (2) translocation is undirectional; (3) translocation is processive to an extent that depends on the base composition of the DNA employed, with the average distance translocated per binding event ranging from 60 to 700 nucleotide residues; and (4) the detailed translocation mechanism of gp41 includes an obligatory slow step before or after the ATP-driven translocation process. Defined lengths of natural and homopolymer single-stranded DNA have also been created as gaps of known length distribution between clusters of gene 32 protein (gp32) bound along long single stranded DNA molecules. ATPase data obtained with cofactors of this type also show unidirectional ATP-driven translocation of gp41 on both natural and homopolymeric single-stranded DNA. Direct binding studies of gp41 to short dT oligomers reveal two further features of the interaction of gp41 to single stranded DNA: (1) nucleoside triphosphate binding is necessary for the formation of stable gp41-ssDNA complexes; and (2) the DNA binding site size of gp41 is between 12 and 20 nucleotide residues per protein monomer. Possible translocation mechanisms for gp41 are discussed within the context of these results.

Decision time unmasked: Individuals adopt different strategies

Abstract The decision time/movement time (DT/MT) measures which are obtained when using reaction-time apparatus incorporating a home key are being used to investigate a wide range of group differences. It is usually assumed that the time from stimulus onset to release of the home key is a good measure of central processing speed. It is argued that it is not always the case since a possible strategy is to release the home key on or just after detecting rather than fully identifying the stimulus, thus giving an invalidly short DT and long MT. Two experiments are described which show subjects do use such a detection strategy when they can. An alternative procedure which masks out stimulus information when the home key is released is shown to make subjects use a full decision strategy and release the home key only after processing sufficient information to respond correctly, thus giving a better measure of cognitive time.