Polysaccharides of Calcareous Algae and Their Effect on the Calcification Process

The composition and structure of polysaccharides from several groups of calcareous algae (including calcareous cyanobacteria), which differ in the calcification mode (extracellular, cell wall, or intracellular), are reviewed. Two families of marine algae, Corallinaceae (Rhodophyta) and Coccolithophoraceae (Prymnesiophyta = Haptophyta), are considered in detail; they exhibit the cell wall and intracellular calcification modes, respectively, and synthesize unusual polysaccharides that seem to directly participate in the calcification process.     

Two-Step Solid Lipid Extrusion as a Process to Modify Dissolution Behavior

Extrudates based on varying ratios of the triglyceride tripalmitin and the hydrophilic polymer polyethylene glycol as matrix formers were produced as oral dosage forms with controlled release characteristics. The extrudates were processed below the melting points of the excipients and contained the hydrophobic model drug chloramphenicol. The influence of the ratio of the matrix formers on drug dissolution was investigated, with an increase in the water-soluble polymer content increasing the drug release rate. In addition, the effect of varying the extrusion process on the extrudate structure and drug dissolution was investigated. Two-step extrusion was performed, which comprised an initial extrusion step of drug and one matrix component followed by milling these extrudates and a second extrusion step for the milled extrudates mixed with the second matrix component. Initial extrusion with polyethylene glycol led to increased dissolution rates, while initial extrusion with tripalmitin led to decreased dissolution rates compared to the dissolution characteristics of extrudates containing the same composition produced by one-step extrusion. Thus, two-step solid lipid extrusion can successfully be used as a process to modify the dissolution behavior of extrudates.     

应用ROC曲线分析钙化点分布及形态特征对乳腺癌诊断的价值

目的：探讨应用ROC曲线分析钙化点分布及形态特征对乳腺癌诊断的价值。方法：收集由超声影像检查发现钙化点并最终经病理诊断为乳腺癌的198例患者的影像资料,通过ROC曲线分析钙化点分布情况及其形态特征,包括单位面积个数、不同形态钙化的概率、区域平均直径、最长直径的差异等。采用ROC曲线分析数据,了解其对乳腺癌的诊断价值,并确认其最佳临界值。结果：恶性病变组中钙化点分布最佳单位面积个数是34个／m2,区域平均直径22．98mm,长径差异1．41ram,沙砾样钙化率占78．9％,线样分支状钙化率51．2％;ROC曲线下面积各为：0．745、0．756、0．678、0．860、0．900。其中线样分支状钙化率诊断准确率最高。结论：各种钙化分布的特征均有诊断效能,但单一的因素存在局限性,综合检测多项特征能有效的提高准确率。     

Presence of Protein Complex is Prerequisite for Aragonite Crystallization in the Nacreous Layer

Abstract We have isolated a protein complex from the nacreous layer of pearl beads and oyster shells. This complex was mainly composed of pearlin and pearl keratin. Addition of a minute amount of the complex to a calcium-carbonate-saturated solution containing Mg²⁺ induced aragonite crystallization. The complex was dissociated to individual components in the presence of EDTA and urea. Conversely, the complex was reconstituted from a mixture of components upon incubation with Ca²⁺ and urea. The mixture of the components was unable to induce aragonite crystallization, but the reconstituted complex recovered this capacity. Thus it is concluded that the complex is the indivisible functional unit required for aragonite crystallization.     

Shell Growth in the Marine Environment: Approaches to the Problem of Marginal Calcification

Although marine waters are usually found to be supersaturatedwith respect to both calcite and aragonite, natural precipitationof these carbonate minerals is very restricted. This is apparentlydue to the occupancy and effective removal of lattice sitesby random organic molecules present in natural seawater. Despite this, many marine organisms build external shells orskeletons of calcium carbonate, utilizing various ingeniousmethods to prevent seawater contamination at the growing shellmargin. The periostracum, which apparently evolved as an aidto marginal calcification, has undergone numerous modificationsserving important secondary functions inspecialized groups.     

Aragonite crystallization in a Christmas-tree model microfluidic device with the addition of magnesium ions

Aragonite is an important dimorph of calcium carbonate, industrially and biologically. However, aragonite is so thermodynamically unstable that it is difficult to understand its formation mechanism. A continuous microfluidic system was employed, in which crystallization was induced only by diffusion in a micron-scale channel. Calcium carbonate (CaCO₃) formed by liquid-liquid reaction and magnesium ions (Mg²⁺) were used as additives. To assess the influence of Mg²⁺ concentration, the Mg²⁺/Ca²⁺ molar ratio was set to 1, 3, and 5. Laminar streams flowed in the detection channel with different concentration gradients. The initial crystallization time (t_I.C) increased exponentially and the density of crystals decreased as the Mg²⁺ ion concentration increased. Following transformation of all particles into snowman or sphere shapes, they became spinose sphere-shaped crystals, which was the final form in this study.     

Determination of End Point of Primary Drying in Freeze-Drying Process Control

Freeze-drying is a relatively expensive process requiring long processing time, and hence one of the key objectives during freeze-drying process development is to minimize the primary drying time, which is the longest of the three steps in freeze-drying. However, increasing the shelf temperature into secondary drying before all of the ice is removed from the product will likely cause collapse or eutectic melt. Thus, from product quality as well as process economics standpoint, it is very critical to detect the end of primary drying. Experiments were conducted with 5% mannitol and 5% sucrose as model systems. The apparent end point of primary drying was determined by comparative pressure measurement (i.e., Pirani vs. MKS Baratron), dew point, Lyotrack (gas plasma spectroscopy), water concentration from tunable diode laser absorption spectroscopy, condenser pressure, pressure rise test (manometric temperature measurement or variations of this method), and product thermocouples. Vials were pulled out from the drying chamber using a sample thief during late primary and early secondary drying to determine percent residual moisture either gravimetrically or by Karl Fischer, and the cake structure was determined visually for melt-back, collapse, and retention of cake structure at the apparent end point of primary drying (i.e., onset, midpoint, and offset). By far, the Pirani is the best choice of the methods tested for evaluation of the end point of primary drying. Also, it is a batch technique, which is cheap, steam sterilizable, and easy to install without requiring any modification to the existing dryer.     

Estimating the Audibility of Industrial Noise to Denning Polar Bears

Oil and gas activities on Alaska's North Slope overlap spatially with polar bear (Ursus maritimus) maternal denning habitat and temporally with the peri-partum and emergence periods. Noise associated with these activities can be substantial and concerns regarding the effects on polar bears have been acknowledged. But the secluded and ephemeral nature of subnivean maternal dens renders the measurement of behavioral and physiological responses of bears to noise exposure challenging, except for rare cases when disturbance-prompted den abandonment has been documented. These limitations, coupled with the uncertainty associated with the synergistic effects of anthropogenic activities on bears in a rapidly changing Arctic, prompt the need to develop predictive models of disturbance to ensure management guidelines effectively mitigate disturbance. Towards this end, we characterized noise propagation from 9 sources (2 aircraft, 2 over-tundra tracked vehicles, 4 wheeled on-road vehicles, and humans walking) used to support industrial activities around artificial snow dens near Milne Point, Alaska, USA, in March–April 2010. We built dens in 4 configurations to mimic variability in den roof thickness and to evaluate differences in noise propagation from when the den was closed compared to being open, similar to den emergence. We integrated these data with an existing polar bear audiogram and developed models to predict auditory-detection probabilities as a function of distance from the den. Within a closed den, aircraft had high probabilities (detection probability ≥75%) of being detected by polar bears at distances ≤1.6 km and ground-based sources had high probabilities of detection at distances ≤0.8 km. On average, closed dens reduced noise levels by 15 decibels (dB) relative to open dens. Our findings indicate that although polar bear snow dens effectively attenuate acoustic sound pressure levels, noise from some industrial support vehicles was likely to be detected farther from dens than previously documented. These results reinforce the importance of maintaining buffer zones around polar bear dens to minimize the potential for den disturbance. © 2020 The Wildlife Society.     

Polar bear responses to the underwater vocalizations of ringed seals

Summary Two captive polar bears were exposed to six different marine mammal vocalizations, in an attempt to determine if polar bears would selectively respond to the underwater vocalization of their primary prey, ringed seals. Vocalizations were played to each bear for a total of eight minutes while their behavioral responses were observed. An analysis of activity indicated that the bears displayed a significantly stronger response to ringed seals' vocalizations. It is theorized that the ability to recognize the underwater vocalizations of their primary prey would increase a bear's probability of a successful capture when a ringed seal rises to breath at an ice bound breathing hole.     

Application of Modeling to Scale-up Dissolution in Pharmaceutical Manufacturing

Liquid mixing scale-up in pharmaceutical industry has often been based on empirical approach in spite of tremendous understanding of liquid mixing scale-up in engineering fields. In this work, we attempt to provide a model-based approach to scale-up dissolution process from a 2 l lab-scale vessel to a 4,000 l scale vessel used in manufacturing. Propylparaben was used as a model compound to verify the model predictions for operating conditions at commercial scale that would result in similar dissolution profile as observed in lab scale. Geometric similarity was maintained between both of the scales to ensure similar mixing characteristics. We utilized computational fluid dynamics (CFD) to ensure that the operating conditions at laboratory and commercial scale will result in similar power per unit volume (P/V). Utilizing this simple scale-up criterion of similar P/V across different scales, results obtained indicate fairly good reproducibility of the dissolution profiles between the two scales. Utilization of concepts of design of experiments enabled summarizing scale-up results in statistically meaningful parameters, for example −90% dissolution in lab scale at a given time under certain operating conditions will result in 75–88% at commercial scale with 95% confidence interval when P/V is maintained constant across the two scales. In this work, we have successfully demonstrated that scale-up of solid dissolution can be done using a systematic process of lab-scale experiments followed by simple CFD modeling to predict commercial-scale experimental conditions.     

Polar transport related to mobilization of plant constituents

Indole-3-acetic acid (IAA), 2-methoxy-3,6-dichlorobenzoic acid (dicamba), sucrose, and mannitol, were tested for polar transport through 5-mm hypocotyl segments of bean (Phaseolus vulgaris var. Pinto) seedlings. All 4 compounds were transported in a polar direction. Autoradiographs of segments through which ¹⁴C-labeled compounds were transported indicated areas of ¹⁴C concentration near the morphological base of segments. There was a direct correlation of IAA transport with the ability to initiate roots as well as with the degree of ¹⁴C accumulation in the morphological base of segments. Unlabeled IAA in lanolin applied to segments appeared to reduce transport of IAA-¹⁴C through those segments when measured by the accumulation of ¹⁴C in a receiver-block of agar, caused an increase in ¹⁴C accumulation in the region to which the unlabeled IAA was applied, and also caused a decrease in accumulation of ¹⁴C at the morphological base of upright segments. Histological studies showed that IAA accelerated cell division and the formation of root primordia particularly at the basal ends, and that these responses sometimes occurred at the expense of cell proliferation at the apical ends of segments. The data presented support the hypothesis that polar movement of IAA, and other endogenous and exogenous substances, in isolated stem segments was controlled by mobilization and utilization of plant constituents at the growth centers.     

The Contribution of Arterial Calcification to Peripheral Arterial Disease in Pseudoxanthoma Elasticum

Background and aims

The contribution of arterial calcification (AC) in peripheral arterial disease (PAD) and arterial wall compressibility is a matter of debate. Pseudoxanthoma elasticum (PXE), an inherited metabolic disease due to ABCC6 gene mutations, combines elastic fiber fragmentation and calcification in various soft tissues including the arterial wall. Since AC is associated with PAD, a frequent complication of PXE, we sought to determine the role of AC in PAD and arterial wall compressibility in this group of patients.

Methods and Results

Arterial compressibility and patency were determined by ankle-brachial pressure index (ABI) in a cohort of 71 PXE patients (mean age 48±SD 14 yrs, 45 women) and compared to 30 controls without PAD. Lower limb arterial calcification (LLAC) was determined by non-contrast enhanced helicoidal CT-scan. A calcification score (Ca-score) was computed for the femoral, popliteal and sub-popliteal artery segments of both legs. Forty patients with PXE had an ABI<0.90 and none had an ABI>1.40. LLAC increased with age, significantly more in PXE subjects than controls. A negative association was found between LLAC and ABI (r = −0.363, p = 0.002). The LLAC was independently associated with PXE and age, and ABI was not linked to cardiovascular risk factors.

Conclusions

The presence of AC was associated with PAD and PXE without affecting arterial compressibility. PAD in PXE patients is probably due to proximal obstructive lesions developing independently from cardiovascular risk factors.