Effects of Process Parameters on Physical and Biological Properties of a Small Caliber Vascular Prosthesis

1991 ◽  
Vol 252 ◽  
Author(s):  
R. M. Carr ◽  
B. A. Ekstein ◽  
P. D. Kemp ◽  
K. D. O'Neil ◽  
C. B. Weinberg ◽  
...  
Keyword(s):  
Ionic Strength ◽  
Self Assembly ◽  
Biological Properties ◽  
Vascular Prosthesis ◽  
Fibrillar Collagen ◽  
Short Term ◽  
Burst Strength ◽  
Concentrating Solution

ABSTRACTA method is described for the production of collagen constructs formed from densely packed, native-banded collagen fibrils. This “Dense Fibrillar Collagen” is formed by concentrating collagen in situ prior to self assembly of the collagen into fibrils. The effect of altering the pH, ionic strength, and osmolarity of the concentrating solution was measured. Increasing the ionic strength and osmolarity of the concentrating solution increased the burst strength of the constructs; increasing the pH from 3.8 to 7.1 reduced the surface fibrillarity, degree of platelet uptake and “short term in vivo thrombogenicity. This construct is being considered as the basis of a small-caliber vascular prosthesis to support guided tissue regeneration.

In vitro and in vivo polysaccharides assembly: ultrastructural and cytochemical study of growing plant cell wall components.

1978 ◽  
Vol 36 (2) ◽  
pp. 434-435
Author(s):  
D. Reis ◽  
B. Vian ◽  
J. C. Roland
Keyword(s):  
Cell Wall ◽  
Self Assembly ◽  
Plant Cell Wall ◽  
Higher Plants ◽  
Three Dimensional ◽  
Cytochemical Study ◽  
Wall Components

Wall morphogenesis in higher plants is a problem still open to controversy. Until now the possibility of a transmembrane control and the involvement of microtubules were mostly envisaged. Self-assembly processes have been observed in the case of walls of Chlamydomonas and bacteria. Spontaneous gelling interactions between xanthan and galactomannan from Ceratonia have been analyzed very recently. The present work provides indications that some processes of spontaneous aggregation could occur in higher plants during the formation and expansion of cell wall.Observations were performed on hypocotyl of mung bean (Phaseolus aureus) for which growth characteristics and wall composition have been previously defined.In situ, the walls of actively growing cells (primary walls) show an ordered three-dimensional organization (fig. 1). The wall is typically polylamellate with multifibrillar layers alternately transverse and longitudinal. Between these layers intermediate strata exist in which the orientation of microfibrils progressively rotates. Thus a progressive change in the morphogenetic activity occurs.

scholarly journals Development of In Situ Self-Assembly Nanoparticles to Encapsulate Lopinavir and Ritonavir for Long-Acting Subcutaneous Injection

Pharmaceutics ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 904
Author(s):  
Irin Tanaudommongkon ◽  
Asama Tanaudommongkon ◽  
Xiaowei Dong
Keyword(s):  
Sustained Release ◽  
Trough Concentration ◽  
Self Assembly ◽  
Subcutaneous Injection ◽  
Drug Loading ◽  
Entrapment Efficiency ◽  
Long Acting

Most antiretroviral medications for human immunodeficiency virus treatment and prevention require high levels of patient adherence, such that medications need to be administered daily without missing doses. Here, a long-acting subcutaneous injection of lopinavir (LPV) in combination with ritonavir (RTV) using in situ self-assembly nanoparticles (ISNPs) was developed to potentially overcome adherence barriers. The ISNP approach can improve the pharmacokinetic profiles of the drugs. The ISNPs were characterized in terms of particle size, drug entrapment efficiency, drug loading, in vitro release study, and in vivo pharmacokinetic study. LPV/RTV ISNPs were 167.8 nm in size, with a polydispersity index of less than 0.35. The entrapment efficiency was over 98% for both LPV and RTV, with drug loadings of 25% LPV and 6.3% RTV. A slow release rate of LPV was observed at about 20% on day 5, followed by a sustained release beyond 14 days. RTV released faster than LPV in the first 5 days and slower than LPV thereafter. LPV trough concentration remained above 160 ng/mL and RTV trough concentration was above 50 ng/mL after 6 days with one subcutaneous injection. Overall, the ISNP-based LPV/RTV injection showed sustained release profiles in both in vitro and in vivo studies.

Phosphofructokinase activity and acidosis during short-term tetanic contractions

1991 ◽  
Vol 69 (2) ◽  
pp. 298-304 ◽  
Author(s):  
Lawrence L. Spriet
Keyword(s):  
Glycolytic Enzyme ◽  
Test Tube ◽  
Mammalian Skeletal Muscle ◽  
Short Term ◽  
Short Supply ◽  
In Vivo Experiments ◽  
Anaerobic Energy

Anaerobic energy production is essential for the production of muscular tension when the demand for energy is greater than can be provided aerobically and when oxygen is in short supply. The largest source of anaerobic energy is from the glycolytic pathway. With sustained tetanic contractions, muscle glycolytic activity is high and hydrogen ions (H+) accumulate while tension production decreases. The increasing [H+] and decreasing tension led to the suggestion that H+ inhibits the activity of the regulatory glycolytic enzyme phosphofructokinase (PFK). Early in vitro work confirmed the H+ sensitivity of PFK in the test tube, indicating that little PFK activity should persist at a pH of 6.9–7.0. However, in situ and in vivo experiments suggested that significant PFK activity was maintained during intense contractions when muscle pH decreased to 6.4–6.6. There are several concerns associated with the application of in vitro findings to in vivo exercise situations: (i) there is little in vitro work in mammalian skeletal muscle with substrate and modulator concentrations representative of exercise, (ii) most in vitro analyses of PFK activity are performed following the dilution of the enzyme in mediums with low protein concentration, and (iii) do the modulators identified in vitro exist in high enough in vivo concentrations at rest and during exercise to contribute to the regulation of PFK? More recent in vitro and in situ PFK experiments have overcome some of these concerns. They confirm that during intense, short-term tetanic contractions, PFK activity is well matched to the ATP demand despite decreases in pH to ~6.4–6.5. A combination of decreased inhibitor (ATP) and increased substrate (fructose 6-phosphate) contents coupled with increases in the contents of several positive modulators may be responsible for the maintained PFK activity. This combination reduces the pH-dependent ATP inhibition of PFK and extends the physiological pH range of the enzyme to the range normally measured during this type of muscular activity.Key words: glycolysis, phosphofructokinase, anaerobic metabolism, acidosis.

scholarly journals Bioorthogonal cyclization-mediated in situ self-assembly of small-molecule probes for imaging caspase activity in vivo

2014 ◽  
Vol 6 (6) ◽  
pp. 519-526 ◽  
Author(s):  
Deju Ye ◽  
Adam J. Shuhendler ◽  
Lina Cui ◽  
Ling Tong ◽  
Sui Seng Tee ◽  
...  
Keyword(s):  
Small Molecule ◽  
Self Assembly ◽  
Caspase Activity ◽  
Small Molecule Probes

Recent advances in stimuli-responsive in situ self-assembly of small molecule probes for in vivo imaging of enzymatic activity

2021 ◽  
Author(s):  
Yuqi Wang ◽  
Jianhui Weng ◽  
Xidan Wen ◽  
Yuxuan Hu ◽  
Deju Ye
Keyword(s):  
Enzymatic Activity ◽  
Small Molecule ◽  
Self Assembly ◽  
In Vivo Imaging ◽  
Molecular Probes ◽  
Stimuli Responsive ◽  
Small Molecule Probes ◽  
Recent Advances

Stimuli-responsive in situ self-assembly of small molecule probes into nanostructures has been promising for the construction of molecular probes for in vivo imaging.

scholarly journals Quantitative Disassembly and Reassembly of Human Papillomavirus Type 11 Viruslike Particles In Vitro

1998 ◽  
Vol 72 (1) ◽  
pp. 32-41 ◽  
Author(s):  
Michael P. McCarthy ◽  
Wendy I. White ◽  
Frances Palmer-Hill ◽  
Scott Koenig ◽  
Joann A. Suzich
Keyword(s):  
Human Papillomavirus ◽  
Ionic Strength ◽  
Self Assembly ◽  
Disulfide Bonds ◽  
Structural Protein ◽  
Homogeneous Population ◽  
Carbonate Buffer ◽  
Viruslike Particles

ABSTRACT The human papillomavirus (HPV) capsid is primarily composed of a structural protein denoted L1, which forms both pentameric capsomeres and capsids composed of 72 capsomeres. The L1 protein alone is capable of self-assembly in vivo into capsidlike structures referred to as viruslike particles (VLPs). We have determined conditions for the quantitative disassembly of purified HPV-11 L1 VLPs to the level of capsomeres, demonstrating that disulfide bonds alone are essential to maintaining long-term HPV-11 L1 VLP structure at physiological ionic strength. The ionic strength of the disassembly reaction was also important, as increased NaCl concentrations inhibited disassembly. Conversely, chelation of cations had no effect on disassembly. Quantitative reassembly to a homogeneous population of 55-nm, 150S VLPs was reliably achieved by the re-formation of disulfide linkages following removal of reducing agent at near-neutral pH and moderate NaCl concentration. HPV-11 L1 VLPs could also be dissociated by treatment with carbonate buffer at pH 9.6, but VLPs could not be regenerated following carbonate treatment. When probed with conformationally sensitive and/or neutralizing monoclonal antibodies, both capsomeres generated by disulfide reduction of purified VLPs and reassembled VLPs formed from capsomeres upon removal of reducing agents exhibited epitopes found on the surface of authentic HPV-11 virions. Antisera raised against either purified VLP starting material or reassembled VLPs similarly neutralized infectious HPV-11 virions. The ability to disassemble and reassemble VLPs in vitro and in bulk allows basic features of capsid assembly to be studied and also opens the possibility of packaging selected exogenous compounds within the reassembled VLPs.

Effects ofPseudomonas aeruginosaendotoxin on vasodilation in the intact spinotrapezius muscle

2001 ◽  
Vol 91 (1) ◽  
pp. 351-356 ◽  
Author(s):  
Hideyuki Suzuki ◽  
Hiroyuki Ikezaki ◽  
Rinku Chandiwala ◽  
Dennis Hong ◽  
Israel Rubinstein
Keyword(s):  
Methyl Ester ◽  
Skeletal Muscles ◽  
Peripheral Circulation ◽  
Sepsis Syndrome ◽  
Short Term ◽  
Short Term Exposure ◽  
Synthase Inhibitor ◽  
Vasomotor Dysfunction

The purpose of this study was to determine whether short-term exposure to clinically relevant concentrations of Pseudomonas aeruginosa lipopolysaccharide (LPS) impairs vasoreactivity of resistance arterioles in the intact spinotrapezius muscle microcirculation and, if so, to determine the mechanisms mediating this response. Using intravital microscopy, we found that 60-min suffusion of P. aeruginosa LPS (0.03–3.0 μg/ml) on the in situ hamster spinotrapezius muscle elicited an immediate, profound, and prolonged concentration-dependent vasodilation ( P < 0.05). This response was reversible once suffusion of P. aeruginosa LPS was stopped. Pretreatment with NG-nitro-l-arginine methyl ester (10.0 μM), a nonselective nitric oxide (NO) synthase inhibitor, but not NG-nitro-d-arginine methyl ester, abrogated P. aeruginosa LPS-induced vasodilation and elicited a small, albeit significant, vasoconstriction. Indomethacin had no significant effects on P. aeruginosa LPS-induced responses. P. aeruginosa LPS had no significant effects on acetylcholine- and nitroglycerin-induced vasodilation in the spinotrapezius muscle. Collectively, these data indicate that short-term exposure to clinically relevant concentrations of P. aeruginosa LPS evokes an immediate, potent, prolonged, and reversible NO-dependent, prostaglandin-independent vasodilation in skeletal muscles in vivo. We suggest this response could play an important role in the pathophysiology of the profound vasomotor dysfunction observed in the peripheral circulation of patients with P. aeruginosa sepsis syndrome.

Carboxyfluorescein (CFSE) Labelling of Hepatocytes for Short-Term Localization following Intraportal Transplantation

1994 ◽  
Vol 3 (5) ◽  
pp. 397-408 ◽  
Author(s):  
Hikaru Fujioka ◽  
Peter J. Hunt ◽  
Jacek Rozga ◽  
Guo-Du Wu ◽  
Donald V. Cramer ◽  
...  
Keyword(s):  
Fluorescence Microscopy ◽  
Isolated Hepatocytes ◽  
Facs Analysis ◽  
Short Term ◽  
Tissue Sections ◽  
Donor Cells ◽  
Portal Vein Infusion

Renewed interest in the transplantation of isolated hepatocytes into the liver as a potential therapy for liver disease has stimulated the development of methods for the identification of donor cells within the recipient organ. We describe a method for cellular tagging and in vivo identification of intraportally transplanted hepatocytes using an intracellular fluorescent dye, 5(6)-carboxyfluorescein diacetate, succinimidyl-ester (CFSE). Rat and porcine hepatocytes were isolated and labelled with CFSE. The optimal conditions for labelling consisted of a buffered saline suspension of hepatocytes (5 × 106 cells/mL) in 20.0 μM CFSE incubated for 15 min at 37°C. In vitro, labelled hepatocytes were cultured either on fibronectin-coated chamber slides or in culture flasks. Cultures were evaluated in situ by fluorescence photomicrography or by fluorescence-activated cell sorting (FACS) after cell detachment. Cell viability was assessed serially and cultured, labelled hepatocytes retained the dye for up to 3 wk (last day of study). CFSE did not effect hepatocyte viability and there was no evidence of intercellular diffusion of the dye. In vivo, syngeneic Lewis rats underwent selective portal vein infusion of freshly isolated, labelled hepatocytes (2.0 × 107 cells/2.0 mL saline/animal) into the posterior liver lobes. All recipients were sacrificed 48 h and 96 h later and their livers examined. Transplanted hepatocytes were identified by fluorescence microscopy in tissue sections and by FACS following collagenase digestion of the liver tissue. CFSE persisted in a population of viable, engrafted hepatocytes. FACS analysis demonstrated that 9 ± 3% of the hepatocytes in the posterior liver lobes were labelled 48 and 96 h after transplantation. At 96 h following transplantation, multiple engrafted hepatocytes could be observed by fluorescence microscopy around the central veins. CFSE labelling allows for both in vitro identification and in vivo localization of donor hepatocytes. Furthermore, it appears to be more stable and specific for labelling hepatocytes than other tested dyes (especially DiI).

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