Sympathetic arterial baroreflex hysteresis in humans: different patterns during low- and high-pressure levels

The findings show that the arterial baroreflex processes diastolic pressure dependent on the direction of pressure change from the previous beat, yielding two distinct baroreflex response curves to falling and rising pressure. Overall, the falling pressure curve is rightward shifted and more sensitive. The rightward shift caused a hysteresis reversal at hypotensive pressures as the falling pressure saturation plateau of the sigmoid response curve occurred at higher pressures than the rising pressure curve.

OR07-04 A Novel Ex Vivo Live-Cell Interrogative Assay of Human Parathyroid Tissue Reveals Distinct Mechanisms of Calcium Sensing Failure in Primary, Secondary, and Tertiary Hyperparathyroidism

Disruption of calcium homeostasis is common to all forms of hyperparathyroidism (HPT), but the underlying biochemical mechanisms that distinguish the various forms of HPT pathology remain poorly characterized. We previously have observed that the kinetics and amplitude of CASR-mediated signaling vary significantly among parathyroid (PT) adenomas and found specific functional and gene expression profiles preferentially associated with increased risk of bone density loss. While these data established a clear connection between CASR activity and clinical phenotype, a direct comparison of the kinetics of PTH secretory behavior between normal and neoplastic intact human PT tissue has yet to be performed. Utilizing eucalcemic normal human organ donor tissues (n=3) as a reference standard, we examined a series of cryopreserved live PT tissue specimens obtained from patients with primary (n=9), secondary (n=12) and tertiary (n=5) HPT. PT tissue fragments matched for viability, mass, and cellular content were placed on permeable membranes and exposed to a series of extracellular calcium concentrations over equivalent time intervals of challenge and normocalcemic recovery to interrogate dynamic PTH secretory induction or suppression. As expected, normal tissue exhibited a sigmoid response curve indicative of allosteric calcium-mediated inhibition, with a mean EC50 of 0.95 mM (95% CI: 0.859–1.254). In contrast, the majority of primary HPT adenomas (n=6) displayed a concave response curve indicative of non-competitive inhibition, consistent with a primary sensing deficit, such as loss of CASR expression. Two distinct PTH secretory behaviors were observed in secondary HPT specimens. One subset (secondary type 1, n=4) retained a sigmoid response curve but with a modest EC50 increase (mean EC50=1.50 mM, 95% CI: 1.41–1.61) and maximal suppression similar to normal tissue, features reflective of competitive inhibition in response to elevated calcium. This pattern could indicate enhanced CASR antagonist activity relative to normal tissue. A second subset, (secondary type 2, n=8) demonstrated a large EC50 shift (mean EC50=2.46 mM; 95% CI: 1.844–2.621), a sigmoid response curve, and an elevated threshold of persistent PTH secretion at high calcium conditions. These parameters are suggestive of non-competitive inhibitory behavior, consistent with loss of a CASR-dependent downstream effector. Three of the primary HPT adenomas shared this response phenotype. Of the tertiary specimens, four matched the primary HPT adenoma pattern, while one exhibited secondary type 2 behavior. These results reveal a series of progressively attenuated dynamic response patterns, where PTH secretion becomes increasingly uncoupled from extracellular calcium sensing. These findings suggest that primary, secondary, and tertiary HPT arise through distinct mechanisms of calcium sensing failure.

Increase in oil content and changes in quality of macauba mesocarp oil along storage

Macauba is an oleaginous palm species from Latin America. It is a rich source of vegetable oil with diverse benefits. However, there are several gaps in assuring post-harvest oil quality of the mesocarp. Thus, ripe fruits were stored at room temperature for 60 days before oil extraction to evaluate fruit and mesocarp oil quality attributes. Physical (decay incidence, water activity), biochemical (specific activity of lipase), physicochemical (acidity and peroxide indices, molar absorptivity at K232 and K270, oxidative stability, total carotene content and mesocarp colour) analyses were carried out. Results show that nonlinear sigmoid response was obtained for most of the parameters evaluated. Decaying reactions related to microorganism’s growth, free fatty acid release and oxidation took place along storage. However, the overall oil quality was in the acceptable limits up to 20 days of storage. It is much further than palm oil, the main source of oil in the world.

Some sigmoid and reverse-sigmoid response patterns emerging from high-power loading of solids

The objective of the present review is twofold. First, it aims at highlighting some sigmoid and reverse-sigmoid response patterns observed recently in the course of simulations of the high-strain-rate loading of (mostly, quasibrittle) solids. Second, it aims at reviewing various properties of two models used frequently as curve fitting tools for nonlinear and saturable phenomena. These two models-inspired by the Hill and the Weibull cumulative distribution functions-are bounded by two horizontal asymptotes with a smooth transition between the baseline and the final saturation state, characterized by a non-negative (a non-positive) derivative at each point for the sigmoid (the reverse-sigmoid) shape. Although they were used primarily for data fitting because of their flexibility and effectiveness, these nonlinear models possess other properties useful for the analysis of the irreversible, nonlinear and far-from-equilibrium phenomena. The main features of these two models are systematically examined in this review. In spite of the fact that satisfactory curve-fitting of data could not be considered a proof of causality it could underline a pattern of behavior and, perhaps, provide an investigation guidance.

Growth and Yield Performance of Maize Seeded in Line and Broadcasted to Varying Doses of Nitrogen

Improving production through better agronomic management is continued to feed ever-increasing population. The objective of this study was to quantify the effect of N on maize seeded in line or broadcasted. Treatments included four level of urea nitrogen (N), i.e. 0, 60, 120 and 180 kg ha-1 and two sowing techniques, i.e. drill sowing (improved) and broad cast (farmer practice). Improved method of sowing had improved yield and yield contributing parameters whereas emergence m-2 and biological yield was higher in broadcast method of sowing. Increasing N application had increased biological yield, number of plants at harvest and grains ear-1 linearly. Cobs per plant, grain yield, 1000 grains weight and harvest index showed sigmoid response to N application and was maximum at 120 kg N ha-1. Sowing of maize seed in line method and receiving 120 kg N ha-1 had increased grain yield by 45% over broad cast method of sowing receiving the same dose of nitrogen. However, the farmer practices method had increased the forage (straw) when received higher amount of N, i.e. 180 kg N ha-1. Thus, it is concluded from the experiment that application of 120 kg N ha-1 and seed sown in line had increased the yield and yielding parameters, compared to other treatments and is, therefore, recommended for general cultivation of variety Azam in agro-climatic condition of Peshawar.