scholarly journals Oligo(serine ester) Charge-Altering Releasable Transporters: Organocatalytic Ring-Opening Polymerization and their Use for in Vitro and in Vivo mRNA Delivery

2019 ◽  
Vol 141 (21) ◽  
pp. 8416-8421 ◽  
Author(s):  
Nancy L. Benner ◽  
Rebecca L. McClellan ◽  
Christopher R. Turlington ◽  
Ole A. W. Haabeth ◽  
Robert M. Waymouth ◽  
...  
Keyword(s):  
Ring Opening ◽  
Ring Opening Polymerization

Poly(D,L-lactide/∊-Caprolactone)/Hydroxyapatite Composites as Bone Filler: An in Vivo Study in Rats

2002 ◽  
Vol 25 (12) ◽  
pp. 1174-1179 ◽  
Author(s):  
A. şenköylü ◽  
E. Ural ◽  
K. Kesencì ◽  
A. şìmşek ◽  
ş. Ruacan ◽  
...  
Keyword(s):  
Ring Opening ◽  
Bone Growth ◽  
Bone Defects ◽  
Ring Opening Polymerization ◽  
New Bone Formation ◽  
The Third ◽  
Bone Filler ◽  
Green Polymer ◽  
Animal Tests

In this study, a novel composite bone substitute was implanted in animal models (rats) and their in vivo characteristics were examined. A D,L-lactide and ∊-caprolactone copolymer (Mw: 80,000; Mn:40,000, and PI:2.00) was synthesized by ring-opening polymerization of the respective dimers using stannous octoate as the catalyst. The final ratio of D,L-lactide to ∊-caprolactone obtained by 1NMR was 60/40. Hydroxyapatite (HA) powder was loaded in the copolymer. The HA/copolymer ratio was 60/40 (w/w). These composites were easily shaped by hand. Animal tests were performed on mature wistar rats (n=30). Defects were created on the proximal, the thickest part of the femur. The bone defects of the first group were filled with polymer/HA composite, the second group filled with only HA and the third group was left empty. Histologic examination of bone tissues showed new bone formation around the yellow-green polymer/HA composite material in the first group of animals whereas no evidence of new bone growth was observed in other groups.

scholarly journals Synthesis, Properties, and In Vitro Hydrolytic Degradation of Poly(d,l-lactide-co-glycolide-co-ε-caprolactone)

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Yixiu Liu ◽  
Xizhuang Bai ◽  
A. Liang
Keyword(s):  
Ring Opening ◽  
Degradation Products ◽  
Hydrolytic Degradation ◽  
Ring Opening Polymerization ◽  
Random Copolymers ◽  
Thermal And Mechanical Properties ◽  
Degradation Rates ◽  
Synthesis Properties ◽  
Acidic Degradation

Random copolymers of poly(d,l-lactide-co-glycolide-co-ε-caprolactone) (PLGC) were synthesized by the ring-opening polymerization of d,l-lactide (DLLA), glycolide (GA), andε-caprolactone (CL). The effects of CL on the copolymers were evaluated to prepare suitable copolymers with controlled properties. Our results showed that the CL content significantly influenced the thermal and mechanical properties of the copolymers and that the CL content in compositions could be altered to control properties of random copolymers. The in vitro hydrolytic degradation of the resulting implants showed that the degradation rate of PLGC was lower than that of PLGA, which could markedly reduce acidic degradation products. Finally, we demonstrated that higher CL contents in compositions slowed degradation rates.

scholarly journals Pro-organic radical contrast agents (“pro-ORCAs”) for real-time MRI of pro-drug activation in biological systems

2020 ◽  
Vol 11 (29) ◽  
pp. 4768-4779 ◽  
Author(s):  
Hung V.-T. Nguyen ◽  
Alexandre Detappe ◽  
Peter Harvey ◽  
Nolan Gallagher ◽  
Clelia Mathieu ◽  
...  
Keyword(s):  
Contrast Agents ◽  
Real Time ◽  
Ring Opening ◽  
Organic Radical ◽  
Real Time Monitoring ◽  
Prodrug Activation ◽  
Metathesis Polymerization ◽  
Drug Activation

Pro-organic radical contrast agents (pro-ORCAs) that enable real-time monitoring of doxorubicin prodrug activation in vitro and in vivo are prepared through brush-first ring-opening metathesis polymerization (ROMP).

A competitive ELISA detecting 7-methylguanosine adduct induced by N-nitrosodimethylamine exposure

2005 ◽  
Vol 24 (2) ◽  
pp. 89-94 ◽  
Author(s):  
Vanessa Niot-Mansart ◽  
Arbana Muhamedi ◽  
Jean-Pierre Arnould
Keyword(s):  
Ring Opening ◽  
Limit Of Detection ◽  
Biological Effects ◽  
Metabolic Activation ◽  
Imidazole Ring ◽  
Enzyme Linked Immunosorbent Assay ◽  
Industrial Emissions ◽  
Formed Adduct

N-Nitrosodimethylamine is a chemical compound known to be carcinogenic to animals and probably to humans. It is widespread and it can be found in food, tobacco smoke and in industrial emissions, such as in the rubber industry. N-Nitrosodimethylamine exerts its biological effects after metabolic activation by forming methylating nucleic acids in DNA. The most formed adduct is 7-methylguanosine. Our laboratory has developed and validated a competitive enzyme-linked immunosorbent assay in order to detect this adduct in DNA exposed to N-nitrosodimethylamine in vitro or in vivo. The imidazole ring-opening (iro) of 7-methylguanosine was required because of its stability. When 7-methylguanosine iro and serum were incubated at 48C, the assay was 35 times more sensitive than at 378C (50% inhibition at 37 fmol 7-methylguanosine iro per well at 48C and 1.28 pmol at 378C) with a lower limit of detection at 1.58 fmol 7-methylguanosine iro. This assay is reproducible, can be routinely performed and is sensitive enough to detect 7-methylguanosine adduct in DNA samples from human exposed to N-nitrosodimethylamine. We aim to use this method in further studies on epidemiological assessment in people at high risk, such as smokers.

Induction and Differentiation of Dental Epithelium in Vivo and in Vitro

1982 ◽  
Vol 40 ◽  
pp. 142-145
Author(s):  
E. J. Kollar
Keyword(s):  
Connective Tissue ◽  
Oral Mucosa ◽  
Basal Lamina ◽  
Functional Derivatives ◽  
Specific Source ◽  
Dental Epithelium ◽  
Connective Tissue Stroma

The differentiation and maintenance of many specialized epithelial structures are dependent on the underlying connective tissue stroma and on an intact basal lamina. These requirements are especially stringent in the development and maintenance of the skin and oral mucosa. The keratinization patterns of thin or thick cornified layers as well as the appearance of specialized functional derivatives such as hair and teeth can be correlated with the specific source of stroma which supports these differentiated expressions.

Ultrastructural Correlations between Clonal Human Tumor Colonies and in Vivo Neoplasms

1982 ◽  
Vol 40 ◽  
pp. 210-211
Author(s):  
M.J. Murphy ◽  
R.R. Price ◽  
J.C. Sloman
Keyword(s):  
Cultured Cells ◽  
Human Tumor ◽  
Cell Type ◽  
Tumor Mass ◽  
Initial Cell ◽  
Cloning Assay ◽  
Human Tumor Cloning ◽  
The Relationship

The in vitro human tumor cloning assay originally described by Salmon and Hamburger has been applied recently to the investigation of differential anti-tumor drug sensitivities over a broad range of human neoplasms. A major problem in the acceptance of this technique has been the question of the relationship between the cultured cells and the original patient tumor, i.e., whether the colonies that develop derive from the neoplasm or from some other cell type within the initial cell population. A study of the ultrastructural morphology of the cultured cells vs. patient tumor has therefore been undertaken to resolve this question. Direct correlation was assured by division of a common tumor mass at surgical resection, one biopsy being fixed for TEM studies, the second being rapidly transported to the laboratory for culture.

Ultrastructure of melanocyte-keratinocyte interactions and pigment transfer in vitro

1978 ◽  
Vol 36 (2) ◽  
pp. 650-651
Author(s):  
Raul I. Garcia ◽  
Evelyn A. Flynn ◽  
George Szabo
Keyword(s):  
Direct Injection ◽  
Skin Pigmentation ◽  
Freeze Fracture ◽  
Pigment Granule ◽  
Time Lapse ◽  
Ultrastructural Level ◽  
Lanthanum Tracer ◽  
A Cell

Skin pigmentation in mammals involves the interaction of epidermal melanocytes and keratinocytes in the structural and functional unit known as the Epidermal Melanin Unit. Melanocytes(M) synthesize melanin within specialized membrane-bound organelles, the melanosome or pigment granule. These are subsequently transferred by way of M dendrites to keratinocytes(K) by a mechanism still to be clearly defined. Three different, though not necessarily mutually exclusive, mechanisms of melanosome transfer have been proposed: cytophagocytosis by K of M dendrite tips containing melanosomes, direct injection of melanosomes into the K cytoplasm through a cell-to-cell pore or communicating channel formed by localized fusion of M and K cell membranes, release of melanosomes into the extracellular space(ECS) by exocytosis followed by K uptake using conventional phagocytosis. Variability in methods of transfer has been noted both in vivo and in vitro and there is evidence in support of each transfer mechanism. We Have previously studied M-K interactions in vitro using time-lapse cinemicrography and in vivo at the ultrastructural level using lanthanum tracer and freeze-fracture.

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.

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