The Effect of Tumour Growth on Immune Competence: A Study of DMBA Mammary Carcinogenesis in the Rat

Circulating antibody response to flagella antigen has been measured in three groups of Sprague-Dawley rats after feeding with 7.12.DMBA in an attempt to differentiate carcinogen and tumour growth as causative agents in the depression of immune response seen in these animals. DMBA fed female rats developing tumours had progressive depression of both primary and secondary response as compared to control animals, and 7S and 19S antibody fractions were equally affected. Removal of tumours did not result in recovery of response. Attempts to prevent tumour development by mammectomy after DMBA feeding were unsuccessful, but the similar number of tumours found in this group was associated with an equal degree of antibody depression to that seen in the first experiment. Male animals fed DMBA did not develop malignant tumours, and showed no depression of immune response. Results suggest that tumour development plays a part in the depression of circulating antibody response seen in these animals, but that it is not directly related to the number of tumours, and is not reversible by tumour excision

An exactly solvable self-convolutive recurrence

We consider a self-convolutive recurrence whose solution is the sequence of coefficients in the asymptotic expansion of the logarithmic derivative of the confluent hypergeometic function $U(a,b,z)$. By application of the Hilbert transform we convert this expression into an explicit, non-recursive solution in which the $n$th coefficient is expressed as the $(n-1)$th moment of a measure, and also as the trace of the $(n-1)$th iterate of a linear operator. Applications of these sequences, and hence of the explicit solution provided, are found in quantum field theory as the number of Feynman diagrams of a certain type and order, in Brownian motion theory, and in combinatorics

The Achilles tendon total rupture score : a study of responsiveness, internal consistency and convergent validity on patients with acute Achilles tendon ruptures

Background The Achilles tendon Total Rupture Score was developed by a research group in 2007 in response to the need for a patient reported outcome measure for this patient population. Beyond this original development paper, no further validation studies have been published. Consequently the purpose of this study was to evaluate internal consistency, convergent validity and responsiveness of this newly developed patient reported outcome measure within patients who have sustained an isolated acute Achilles tendon rupture. Methods Sixty-four eligible patients with an acute rupture of their Achilles tendon completed the Achilles tendon Total Rupture Score alongside two further patient reported outcome measures (Disability Rating Index and EQ 5D). These were completed at baseline, six weeks, three months, six months and nine months post injury. The Achilles tendon Total Rupture Score was evaluated for internal consistency, using Cronbach's alpha, convergent validity, through correlation analysis and responsiveness, by analysing floor and ceiling effects and calculating its relative efficiency in comparison to the Disability Rating Index and EQ 5D scores. Results The Achilles tendon Total Rupture Score demonstrated high internal consistency (Cronbachs alpha > 0.8) and correlated significantly (p < 0.001) with the Disability Rating Index at five time points (pre-injury, six weeks, three, six and nine months) with correlation coefficients between -0.5 and -0.9. However, the confidence intervals were wide. Furthermore, the ability of the new score to detect clinically important changes over time (responsiveness) was shown to be greater than the Disability Rating Index and EQ 5D. Conclusions A universally accepted outcome measure is imperative to allow comparisons to be made across practice. This is the first study to evaluate aspects of validity of this newly developed outcome measure, outside of the developing centre. The ATRS demonstrated high internal consistency and responsiveness, with limited convergent validity. This research provides further support for the use of this outcome measure, however further research is required to advocate its universal use in patients with acute Achilles tendon ruptures. Such areas include inter-rater reliability and research to determine the minimally clinically important difference between scores

Fatness, fitness, and cardiometabolic risk factors in middle-aged white men.

The objective was to test the hypothesis that traditional and novel cardiometabolic risk factors would be significantly different in groups of men of different fatness and fitness. Total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides, glucose, insulin, high-sensitivity C-reactive protein, alanine aminotransferase, aspartate aminotransferase, γ-glutamyltransferase, leptin, adiponectin, tumor necrosis factor-α, interleukin-6, interleukin-10, fibrinogen, and insulin resistance were assessed in 183 nonsmoking white men aged 35 to 53 years, including 62 who were slim and fit (waist girth ≤90 cm and maximal oxygen consumption [VO(2)max] above average), 24 who were slim and unfit (waist girth ≤90 cm and VO(2)max average or below), 39 who were fat and fit (waist girth ≥100 cm and VO(2)max above average), and 19 who were fat and unfit (waist girth ≥100 cm and VO(2)max average or below). Seventy-six percent gave blood on 2 occasions, and the average of 1 or 2 blood tests was used in statistical tests. Waist girth (centimeters) and fitness (milliliters of oxygen per kilogram of fat-free mass) were associated with high-density lipoprotein cholesterol, leptin, and insulin resistance after adjustment for age, saturated fat intake, and total energy intake. High-density lipoprotein cholesterol, triglycerides, alanine aminotransferase, and insulin resistance were significantly different in men who were fat and fit and those who were fat and unfit. These data suggest that differences in lipid and lipoprotein concentrations, liver function, and insulin resistance may explain why the risks of chronic disease are lower in men who are fat and fit than those who are fat and unfit

Effective mass and quantum lifetime in a Si/Si0.87Ge0.13/Si two-dimensional hole gas

Measurements of Shubnikov de Haas oscillations in the temperature range 0.3–2 K have been used to determine an effective mass of 0.23 m0 in a Si/Si0.87Ge0.13/Si two-dimensional hole gas. This value is in agreement with theoretical predictions and with that obtained from cyclotron resonance measurements. The ratio of the transport time to the quantum lifetime is found to be 0.8. It is concluded that the 4 K hole mobility of 11 000 cm2 V−1 s−1 at a carrier sheet density of 2.2×1011 cm−2 is limited by interface roughness and short-range interface charge scattering

An engineered Tetrahymena tRNA(Gln) for in vivo incorporation of unnatural amino acids into proteins by nonsense suppression

A new tRNA, THG73, has been designed and evaluated as a vehicle for incorporating unnatural amino acids site-specifically into proteins expressed in vivo using the stop codon suppression technique. The construct is a modification of tRNAGln(CUA) from Tetrahymena thermophila, which naturally recognizes the stop codon UAG. Using electrophysiological studies of mutations at several sites of the nicotinic acetylcholine receptor, it is established that THG73 represents a major improvement over previous nonsense suppressors both in terms of efficiency and fidelity of unnatural amino acid incorporation. Compared with a previous tRNA used for in vivo suppression, THG73 is as much as 100-fold less likely to be acylated by endogenous synthetases of the Xenopus oocyte. This effectively eliminates a major concern of the in vivo suppression methodology, the undesirable incorporation of natural amino acids at the suppression site. In addition, THG73 is 4-10-fold more efficient at incorporating unnatural amino acids in the oocyte system. Taken together, these two advances should greatly expand the range of applicability of the in vivo nonsense suppression methodology

Area distribution and the average shape of a L\'evy bridge

We consider a one dimensional L\'evy bridge x_B of length n and index 0 < \alpha < 2, i.e. a L\'evy random walk constrained to start and end at the origin after n time steps, x_B(0) = x_B(n)=0. We compute the distribution P_B(A,n) of the area A = \sum_{m=1}^n x_B(m) under such a L\'evy bridge and show that, for large n, it has the scaling form P_B(A,n) \sim n^{-1-1/\alpha} F_\alpha(A/n^{1+1/\alpha}), with the asymptotic behavior F_\alpha(Y) \sim Y^{-2(1+\alpha)} for large Y. For \alpha=1, we obtain an explicit expression of F_1(Y) in terms of elementary functions. We also compute the average profile < \tilde x_B (m) > at time m of a L\'evy bridge with fixed area A. For large n and large m and A, one finds the scaling form = n^{1/\alpha} H_\alpha({m}/{n},{A}/{n^{1+1/\alpha}}), where at variance with Brownian bridge, H_\alpha(X,Y) is a non trivial function of the rescaled time m/n and rescaled area Y = A/n^{1+1/\alpha}. Our analytical results are verified by numerical simulations.Comment: 21 pages, 4 Figure

Increased gravitational force reveals the mechanical, resonant nature of physiological tremor

Human physiological hand tremor has a resonant component. Proof of this is that its frequency can be modified by adding mass. However, adding mass also increases the load which must be supported. The necessary force requires muscular contraction which will change motor output and is likely to increase limb stiffness. The increased stiffness will partly offset the effect of the increased mass and this can lead to the erroneous conclusion that factors other than resonance are involved in determining tremor frequency. Using a human centrifuge to increase head-to-foot gravitational field strength, we were able to control for the increased effort by increasing force without changing mass. This revealed that the peak frequency of human hand tremor is 99% predictable on the basis of a resonant mechanism. We ask what, if anything, the peak frequency of physiological tremor can reveal about the operation of the nervous system.This work was funded by a BBSRC Industry Interchange Award to J.P.R.S. and R.F.R. C.J.O. was funded by BBSRC grant BB/I00579X/1. C.A.V. was funded by A∗Midex (Aix-Marseille Initiative of Excellence