Gain and kinetics of activation in the G-protein cascade of phototransduction.

The guanine nucleotide binding protein (G protein) cascade underlying phototransduction is one of the best understood of all signaling pathways. The diffusional interactions of the proteins underlying the cascade have been analyzed, both at a macroscopic level and also in terms of the stochastic nature of the molecular contacts. In response to a single activated rhodopsin (R*) formed as a result of a single photon hit, it can be shown that molecules of the G-protein transducin will be activated approximately linearly with time. This, in turn, will cause the number of activated molecules of the effector protein (the phosphodiesterase) also to increase linearly with time. These kinetics of protein activation provide an accurate description of the time course of the rising phase of the photoreceptor's electrical response over a wide range of flash intensities. Recent estimates indicate that at room temperature each R* triggers activation of the phosphodiesterase at a rate of 1000-2000 subunits.s-1. Now that a quantitative description of the activation steps in transduction has been obtained, perhaps the greatest challenge for the future is to provide a comprehensive description of the shutoff reactions, so that a complete account of the photoreceptor's response to light can be achieved.

Gain of chromosome 3q defines the transition from severe dysplasia to invasive carcinoma of the uterine cervix.

We have chosen tumors of the uterine cervix as a model system to identify chromosomal aberrations that occur during carcinogenesis. A phenotype/genotype correlation was established in defined regions of archived, formalin-fixed, and hematoxylin/eosin-stained tissue sections that were dissected from normal cervical epithelium (n = 3), from mild (n = 4), moderate (n = 6), and severe dysplasias/carcinomas in situ (CIS) (n = 13), and from invasive carcinomas (n = 10) and investigated by comparative genomic hybridization. The same tissues were analyzed for DNA ploidy, proliferative activity, and the presence of human papillomavirus (HPV) sequences. The results show that an increase in proliferative activity and tetraploidization had occurred already in mildly dysplastic lesions. No recurrent chromosomal aberrations were observed in DNA extracted from normal epithelium or from mild and moderate dysplasias, indicating that the tetraploidization precedes the loss or gain of specific chromosomes. A gain of chromosome 3q became visible in one of the severe dysplasias/CIS. Notably, chromosome 3q was overrepresented in 90% of the carcinomas and was also found to have undergone a high-level copy-number increase (amplification). We therefore conclude that the gain of chromosome 3q that occurs in HPV16-infected, aneuploid cells represents a pivotal genetic aberration at the transition from severe dysplasia/CIS to invasive cervical carcinoma.

The angiotensin II type 2 (AT2) receptor antagonizes the growth effects of the AT1 receptor: gain-of-function study using gene transfer.

The type 1 angiotensin II (AT1) receptor is well characterized but the type 2 (AT2) receptor remains an enigma. We tested the hypothesis that the AT2 receptor can modulate the growth of vascular smooth muscle cells by transfecting an AT2 receptor expression vector into the balloon-injured rat carotid artery and observed that overexpression of the AT2 receptor attenuated neointimal formation. In cultured smooth muscle cells, AT2 receptor transfection reduced proliferation and inhibited mitogen-activated protein kinase activity. Furthermore, we demonstrated that the AT2 receptor mediated the developmentally regulated decrease in aortic DNA synthesis at the latter stages of gestation. These results suggest that the AT2 receptor exerts an antiproliferative effect, counteracting the growth action of AT1 receptor.

Gain of function mutations for paralogous Hox genes: implications for the evolution of Hox gene function.

To investigate the functions of paralogous Hox genes, we compared the phenotypic consequences of altering the embryonic patterns of expression of Hoxb-8 and Hoxc-8 in transgenic mice. A comparison of the phenotypic consequences of altered expression of the two paralogs in the axial skeletons of newborns revealed an array of common transformations as well as morphological changes unique to each gene. Divergence of function of the two paralogs was clearly evident in costal derivatives, where increased expression of the two genes affected opposite ends of the ribs. Many of the morphological consequences of expanding the mesodermal domain and magnitude of expression of either gene were atavistic, inducing the transformation of axial skeletal structures from a modern to an earlier evolutionary form. We propose that regional specialization of the vertebral column has been driven by regionalization of Hox gene function and that a major aspect of this evolutionary progression may have been restriction of Hox gene expression.

Effects of internal gain assumptions in building energy calculations /

The utilization of direct solar gains in buildings can be affected by operating profiles, such as schedules for internal gains, thermostat controls, and ventilation rates. Building energy analysis methods use various assumptions about these profiles. This paper describes the effects of typical internal gain assumptions in energy calculations. The results of this study indicate that calculations of annual heating and cooling loads are sensitive to internal gains, but in most cases are relatively insensitive to hourly variation in internal gains.

Zoune chez sa ninnaine : fan'm gain sept sauts pou li passé /

Reprint of the Port-au-Prince 1906 ed.

Le gain mathématique à la bourse; la spéculation de bourse considérée comme jeu de pur hasard, theéorie mathématique de la probabilité en mathière de cours, écarts et équilibres, conjectures alternantes, tableaux et graphiques à l'usage des spéculateurs; exposé theéorique et pratique d'une méthode de spéculation assurant un bénéfice considérable et continuel ...

Mode of access: Internet.

Practical husbandry, or, The art of farming with a certainty of gain : as practised by judicious farmers in this country : the result of experience and long observation /

Goldsmiths'-Kress no. 17579.

Nutrient partitioning during treatment of tuberculosis: gain in body fat mass but not in protein mass

Background: Tuberculosis is an important cause of wasting. The functional consequences of wasting and recovery may depend on the distribution of lost and gained nutrient stores between protein and fat masses. Objective: The goal was to study nutrient partitioning, ie, the proportion of weight change attributable to changes in fat mass (FM) versus protein mass (PM), during anti mycobacterial treatment. Design: Body-composition measures were made of 21 men and 9 women with pulmonary tuberculosis at baseline and after 1 and 6 mo of treatment. All subjects underwent dual-energy X-ray absorptiometry and deuterium bromide dilution tests, and a four-compartment model of FM, total body water (TBW), bone minerals (BM), and PM was derived. The ratio of PM to FM at any time was expressed as the energy content (p-ratio). Changes in the p-ratio were related to disease severity as measured by radiologic criteria. Results: Patients gained 10% in body weight (P < 0.001) from baseline to month 6. This was mainly due to a 44% gain in FM (P < 0.001); PM, BM, and TBW did not change significantly. Results were similar in men and women. The p-ratio decreased from baseline to month 1 and then fell further by month 6. Radiologic disease severity was not correlated with changes in the p-ratio. Conclusions: Microbiological cure of tuberculosis does not restore PM within 6 mo, despite a strong anabolic response. Change in the p-ratio is a suitable parameter for use in studying the effect of disease on body composition because it allows transformation of such effects into a normal distribution across a wide range of baseline proportion between fat and protein mass.

Complete modulational-instability gain spectrum of nonlinear quasi-phase-matching gratings

We consider plane waves propagating in quadratic nonlinear slab waveguides with nonlinear quasi-phase-matching gratings. We predict analytically and verify numerically the complete gain spectrum for transverse modulational instability, including hitherto undescribed higher-order gain bands. (C) 2004 Optical Society of America.

Narrowing of the inferior dental canal in relation to the lower third molars

Objectives: To assess narrowing of the inferior dental canal in the lower third molar regions using computed tomography (CT) and to determine the value of radiographic markers on rotational panoramic radiographs in assessing the true relationships of the inferior dental canal. Methods: Patients referred for CT assessment of impacted lower third molars were used in this study. The lower third molars were assessed using CT to determine the position and morphology of the inferior dental canal relative to the roots and the cortical plates. The radiographic markers on rotational panoramic radiographs were correlated with the CT findings when rotational panoramic radiographs were available. Results: The patients referred had 202 lower third molars. Inferior positioning of the inferior dental canal was the most common location on CT. Narrowing of the inferior dental canal was found in relation to the lower third molars in 66.8% of cases. The chance of narrowing of the inferior dental canal as shown using CT increased when at least one of the radiographic markers, superimposition, narrowing, deviation or reduction in density was present on the rotational panoramic radiograph. Deviation of the inferior dental canal on rotational panoramic radiographs was found to be the most significant predictor of narrowing of the inferior dental canal and a close relationship to the roots, as shown in CT. Conclusions: Narrowing of the inferior dental canal is a common finding when impacted lower third molars are assessed using CT. On rotational panoramic radiographs deviation of the inferior dental canal is the best predictor of narrowing of the inferior dental canal and a close relationship to the roots.

Identifying the energy gap: Magnitude and determinants of 5-year weight gain in midage women

Objective: The aims of this study were to estimate average yearly weight gain in midage women and to identify the determinants of weight gain and gaining weight at double the average rate. Research Methods and Procedures: The study sample comprised 8071 participants (45 to 55 years old) in the Australian Longitudinal Study on Women's Health who completed mailed surveys in 1996, 1998, and 2001. Results: On average, the women gained almost 0.5 kg per year [average 2.42 kg (95% confidence interval, 2.29 to 2.54) over 5 years]. In multivariate analyses, variables associated with energy balance (physical activity, sitting time, and energy intake), as well as quitting smoking, menopause/hysterectomy, and baseline BMI category were significantly associated with weight gain, but other behavioral and demographic characteristics were not. After adjustment for all of the other biological and behavioral variables, the odds of gaining weight at about twice the average rate (> 5 kg over 5 years) were highest for women who quit smoking (odds ratio = 2.94; 95% confidence interval, 2.17, 3.96). There were also independent relationships between the odds of gaining > 5 kg and lower levels of habitual physical activity, more time spent sitting, energy intake (but only in women with BMI > 25 at baseline), menopause transition, and hysterectomy. Discussion: The average weight gain equates with an energy imbalance of only about 10 kcal or 40 kJ per day, which suggests that small sustained changes in the modifiable behavioral variables could prevent further weight gain.

Rhizodeposition and the enhanced mineralization of 2,4-dichlorophenoxyacetic acid in soil from the Trifolium pratense rhizosphere

Enhanced biodegradation of organic xenobiotic compounds in the rhizosphere is frequently recorded although the specific mechanisms are poorly understood. We have shown that the mineralization of 2,4-dichlorophenoxyacetic acid (2,4-D) is enhanced in soil collected from the rhizosphere of Trifolium pratense[e.g. maximum mineralization rate = 7.9 days(-1) and time at maximum rate (t(1)) = 16.7 days for 12-day-old T. pratense soil in comparison with 4.7 days(-1) and 25.4 days, respectively, for non-planted controls). The purpose of this study was to gain a better understanding of the plant-microbe interactions involved in rhizosphere-enhanced biodegradation by narrowing down the identity of the T. pratense rhizodeposit responsible for stimulating the microbial mineralization of 2,4-D. Specifically, we investigated the distribution of the stimulatory component(s) among rhizodeposit fractions (exudates or root debris) and the influence of soil properties and plant species on its production. Production of the stimulatory rhizodeposit was dependent on soil pH (e.g. t(1) for roots grown at pH 6.5 was significantly lower than for those grown at pH 4.4) but independent of soil inorganic N concentration. Most strikingly, the stimulatory rhizodeposit was only produced by T. pratense grown in non-sterile soil and was present in both exudates and root debris. Comparison of the effect of root debris from plant species (three each) from the classes monocotyledon, dicotyledon (non-legume) and dicotyledon (legume) revealed that legumes had by far the greatest positive impact on 2,4-D mineralization kinetics. We discuss the significance of these findings with respect to legume-rhizobia interactions in the rhizosphere.