Hydration Patterns in Sodium Alginate Polymeric Matrix Tablets—The Result of Drug Substance Incorporation

The purpose was to show, using destructive/nondestructive methods, that the interplay between water, tablet structure, and composition determine the unique spatiotemporal hydration pattern of polymer-based matrices. The tablets containing a 1:1 w/w mixture of sodium alginate with salicylic acid (ALG/SA) or sodium salicylate (ALG/SNA) were studied using Karl Fischer titration, differential scanning calorimetry, X-ray microtomography, and magnetic resonance imaging. As the principal results, matrix specific features were detected, e.g., “locking” of the internal part of the matrix (ALG/SA); existence of lamellar region associated with detection of free/freezing water (ALG/SA); existence of water penetrating the matrix forming specific region preceding infiltration layer (ALG/SNA); switch in the onset temperature of endothermic water peak associated with an increase in the fraction of non-freezing water weight per dry matrix weight in the infiltration layer (ALG/SNA). The existence of complicated spatiotemporal hydration patterns influenced by matrix composition and molecular properties of constituents has been demonstrated.

The influence of estrogen deficiency on the structural and mechanical properties of rat cortical bone

Background Post-menopausal osteoporosis is a common health problem worldwide, most commonly caused by estrogen deficiency. Most of the information regarding the skeletal effects of this disease relates to trabecular bone, while cortical bone is less studied. The purpose of this study was to evaluate the influence of estrogen deficiency on the structure and mechanical properties of cortical bone. Methods Eight ovariectomized (OVH) and eight intact (control) Sprague Dawley rats were used.Structural features of femoral cortical bone were studied by light microscopy, scanning electron microscopy and synchrotron-based microcomputer-tomography and their mechanical properties determined by nano-indentation. Results Cortical bone of both study groups contains two distinct regions: organized circumferential lamellae and disordered bone with highly mineralized cartilaginous islands. Lacunar volume was lower in the OVH group both in the lamellar and disorganized regions (182 ± 75 µm3 vs 232 ± 106 µm3, P < 0.001 and 195 ± 86 µm3 vs. 247 ± 106 µm3, P < 0.001, respectively). Lacunar density was also lower in both bone regions of the OVH group (40 ± 18 ×103 lacunae/mm3 vs. 47 ± 9×103 lacunae/mm3 in the lamellar region, P = 0.003 and 63 ± 18×103lacunae/mm3 vs. 75 ± 13×103 lacunae/mm3 in the disorganized region, P < 0.001). Vascular canal volume was lower in the disorganized region of the bone in the OVH group compared to the same region in the control group (P < 0.001). Indentation moduli were not different between the study groups in both bone regions. Discussion Changes to cortical bone associated with estrogen deficiency in rats require high-resolution methods for detection. Caution is required in the application of these results to humans due to major structural differences between human and rat bone.

Mechanical nociceptive assessment of the equine hoof following distal interphalangeal joint intra-articular anesthesia

Background With the hypothesis that equine dorsal lamellar tissue can be desensitized by anesthesia injection into distal interphalangeal joint (DIPJ), the objective was to assess the mechanical nociceptive threshold of hoof dorsal lamellae following intra-articular (IA) administration of lidocaine into this joint. Methods The DIPJ of the forelimbs of six adult healthy horses were injected with either 5 mL of lidocaine, or 5 mL of lactated Ringer’s solution. Treatments were randomly distributed, with each forelimb undergoing a single treatment. The hooves were evaluated pre- and post-injection at pre-selected times over 4 h, using a pressure algometry model. Mechanical nociceptive thresholds (MNTs) were recorded for the sole (dorsal, palmarolateral, and palmaromedial regions), coronary band (medial, lateral, and dorsal regions), heel bulbs (medial and lateral), and dorsal lamellar region (2 cm and 4 cm distal to the coronary band). The MNT means were compared over time using the Friedman test and between treatments using the Wilcoxon signed-rank test, with values of P < 0.05 considered statistically significant. Results There were no differences between treatments for any region of the hoof during the evaluation period. However, MNT values indicating analgesia were recorded in the dorsal lamellar region in 50% of hooves following adminstration of lidocaine into the DIPJ. Conclusion The administration of 5 mL of lidocaine into the DIPJ does not significantly increase the mechanical nociceptive threshold of the equine hoof.

Enhanced performance of piezoelectric composite nanogenerator based on gradient porous PZT ceramic structure for energy harvesting

Oriented layer and interconnected transverse bridges between layers in the progressive lamellar region effectively improved the electromechanical conversion efficiency.

Arf6, JIP3, and dynein shape and mediate macropinocytosis

Macropinocytosis is an actin-driven form of clathrin-independent endocytosis that generates an enlarged structure, the macropinosome. Although many studies focus on signaling molecules and phosphoinositides involved in initiating macropinocytosis, the commitment to forming a macropinosome and the handling of that membrane have not been studied in detail. Here we show in HT1080 cells, a human fibrosarcoma cell line, a requirement for microtubules, dynein, the JIP3 microtubule motor scaffold protein, and Arf6, a JIP3 interacting protein, for the formation and inward movement of the macropinosome. While actin and myosin II also play critical roles in the formation of ruffling membrane, microtubules provide an important tract for initiation, sealing, and transport of the macropinosome through the actin- and myosin-rich lamellar region.

Área mitocondrial relativa nos epitélios branquial e renal do baiacu estuarino tropical Sphoeroides testudineus após aclimatação a água do mar isosmótica

The gills of teleost fishes are responsible both for gas exchangein respiration and salt transport in osmoregulation (JOBLING, 1995; ZADUNAISKY, 1996; PERRY, 1997; VAN DER HEIJDEN et al., 1997; EVANS et al., 1999; EVANS et al., 2005). In marine teleosts the gill epithelium secretes salt mainly through chloride cells (JOBLING, 1995; ZADUNAISKY, 1996; PERRY, 1997; VAN DER HEIJDEN et al., 1997; FERNANDES et al., 1998; EVANS et al., 2005). These cells are typically located between secondary lamellae at their insertion in the gill filament (inter-lamellar region) or in the gill filament itself (LAURENT & DUNEL, 1980; PERRY, 1997; FERNANDES et al., 1998; EVANS et al., 2005). These cells are rounded, display abundant mitochondria, a tubular system of endomembranes, sub-apical vesicles, and extensive intercellular junctional complexes (LAURENT & DUNEL, 1980; JOBLING, 1995; ZADUNAISKY, 1996; PERRy, 1997; EVANS et al., 2005).

Non-sarcomeric mode of myosin II organization in the fibroblast lamellum.

The organization of myosin in the fibroblast lamellum was studied by correlative fluorescence and electron microscopy after a novel procedure to reveal its underlying morphology. An X-rhodamine analog of conventional smooth muscle myosin (myosin II) that colocalized after microinjection with endogenous myosin was used to trace myosin distribution in living fibroblasts. Then, the same cells were examined by EM of platinum replicas. To visualize the structural arrangement of myosin, other cytoskeletal fibrillar structures had to be removed: microtubules were depolymerized by nocodazole treatment of the living cells before injection of myosin; continued nocodazole treatment also induced the intermediate filaments to concentrate near the nucleus, thus removing them from the lamellar region; actin filaments were removed after lysis of the cells by incubation of the cytoskeletons with recombinant gelsolin. Possible changes in myosin organization caused by this treatment were examined by fluorescence microscopy. No significant differences in myosin distribution patterns between nocodazole-treated and control cells were observed. Cell lysis and depletion of actin also did not induce reorganization of myosin as was shown by direct comparison of myosin distribution in the same cells in the living state and after gelsolin treatment. EM of the well-spread, peripheral regions of actin-depleted cytoskeletons revealed a network of bipolar myosin mini-filaments, contracting each other at their terminal, globular regions. The morphology of this network corresponded well to the myosin distribution observed by fluorescence microscopy. A novel mechanism of cell contraction by folding of the myosin filament network is proposed.

Mapping trajectories of Pgp-1 membrane protein patches on surfaces of motile fibroblasts reveals a distinct boundary separating capping on the lamella and forward transport on the retracting tail

Patches of aggregated membrane proteins on motile fibroblasts are transported from the surfaces of the leading lamella to a site just ahead of the nucleus in the phenomenon known as capping. A major cell surface glycoprotein, Pgp-1 (GP80), was tagged with a monoclonal IgG and then aggregated with fluorescent secondary antibodies. Correlated digitized fluorescence and phase-contrast microscopy were used to map the trajectories of fluorescent Pgp-1 patches located in various regions of the cell surface. The response of patches located in lamellar and nonlamellar regions to spontaneous retraction of the trailing cell margin, or tail was examined in detail. During capping, Pgp-1 patches accumulated at a morphologically distinct site on the cell surface, the ‘null border’, corresponding to the boundary between lamelloplasm and endoplasm and the posterior edge of the dorsal cortical F-actin sheath. Posterior to this site, gradual forward movement of patches accompanied the gradual narrowing phase of the trailing edge retraction that occurs prior to abrupt detachment of the tail, but patches did not actually accumulate at the null border. The rate of forward patch movement was generally greater at positions further behind the boundary. Patch movement correlated approximately with forward organelle movement in the trailing region of the cell. The boundary was also apparent during simultaneous capping and retraction when forward patch transport on the trailing edge and rearward transport of patches across the lamellar surface appeared to converge on the null border. Forward patch transport was strictly confined to regions behind the boundary while retrograde patch transport was confined to the lamellar region ahead of the boundary. Patches are thought to be linked to the cortical cytoskeleton and their transport is discussed in terms of the very different cortical cytoskeletal dynamics occurring in the leading and trailing edges of locomoting cells.

Actions of cytochalasins on the organization of actin filaments and microtubules in a neuronal growth cone.

Actions of cytochalasin B (CB) on cytoskeletons and motility of growth cones from cultured Aplysia neurons were studied using a rapid flow perfusion chamber and digital video light microscopy. Living growth cones were observed using differential interference contrast optics and were also fixed at various time points to assay actin filament (F-actin) and microtubule distributions. Treatment with CB reversibly blocked motility and eliminated most of the phalloidin-stainable F-actin from the leading lamella. The loss of F-actin was nearly complete within 2-3 min of CB application and was largely reversed within 5-6 min of CB removal. The loss and recovery of F-actin were found to occur with a very distinctive spatial organization. Within 20-30 s of CB application, F-actin networks receded from the entire peripheral margin of the lamella forming a band devoid of F-actin. This band widened as F-actin receded at rates of 3-6 microns/min. Upon removal of CB, F-actin began to reappear within 20-30 s. The initial reappearance of F-actin took two forms: a coarse isotropic matrix of F-actin bundles throughout the lamella, and a denser matrix along the peripheral margin. The denser peripheral matrix then expanded in width, extending centrally to replace the coarse matrix at rates again between 3-6 microns/min. These results suggest that actin normally polymerizes at the leading edge and then flows rearward at a rate between 3-6 microns/min. CB treatment was also observed to alter the distribution of microtubules, assayed by antitubulin antibody staining. Normally, microtubules are restricted to the neurite shaft and a central growth cone domain. Within approximately 5 min after CB application, however, microtubules began extending into the lamellar region, often reaching the peripheral margin. Upon removal of CB, the microtubules were restored to their former central localization. The timing of these microtubule redistributions is consistent with their being secondary to effects of CB on lamellar F-actin.

The movement of cell clusters in vitro: morphology and directionality

The movement of cells in small groups, or clusters, was studied in vitro using epithelioid cells from Gordon-Kosswig melanomas (from poecelid fish) and time-lapse cinemicrography. Tumour explants cultured on glass yield cell sheets from which groups of cells separate and become independently motile clusters. These clusters typically contain 3–30 cells, but may have as many as 50. They propel themselves at speeds of 0.2-4.0 micrometer/min by means of broad hyaline lamellae. The distribution of lamellae around the perimeter of each cluster correlates with both direction and speed of cluster movement, i.e. a cluster moves with its most lamellar region at its leading edge, and the greater the extent of the leading lamellar region the greater the speed. Also, a cluster tends to keep moving in the same direction. This persistence is due to a relatively constant distribution of lamellae. Cells on the trailing edge usually lack lamellae and most are very elongate and oriented perpendicular to the direction of cluster movement. In general, whenever a cell elongates, there is a loss of lamellar activity along its taut edges, parallel to the axis of elongation. Thus, any region with less lamellar activity would tend to be elongated by the outward pull of the more active regions to either side and would, in consequence, suffer a further reduction in lamellar activity. In this way, the distribution of regions of lamellar activity is self-reinforcing and the result is persistence of movement in a particular direction. This phenomenon could play an important role in giving directionality to certain morphogenetic movements, such as neural crest cell migration.