Cytochemical and enzymatic characterization of the sporulation septum of Streptomyces antibioticus

1981 ◽  
Vol 27 (10) ◽  
pp. 1060-1065 ◽  
Author(s):  
Alfredo F. Braña ◽  
Manuel B. Manzanal ◽  
Carlos Hardisson
Keyword(s):  
Enzymatic Digestion ◽  
Cross Linking ◽  
Dense Matrix ◽  
Enzymatic Characterization ◽  
Chemical Modifications ◽  
Streptomyces Antibioticus ◽  
Highly Sensitive ◽  
Thin Electron ◽  
Electron Dense Matrix

The sporulation septum in Streptomyces antibioticus is formed by two thin electron-dense layers which constitute the annuli, separated by a thick and moderately electron-dense matrix which forms the deposits. By means of cytochemical techniques and enzymatic digestion with lysozyme, we have shown that deposits and annuli have a different chemical composition. Deposits are formed by peptidoglycan and are highly sensitive to lysozyme, whereas annuli, probably due to localized chemical modifications of the peptidoglycan or high degrees of peptide cross-linking, are lysozyme resistant. Our results suggest that the deposits, unlike the annuli, are only temporary assisting structures which are degraded during spore maturation.

Biopolymers with Medical Applications Optimized method for obtaining chitosan-based delivery systems

2018 ◽  
Vol 69 (7) ◽  
pp. 1756-1759 ◽  
Author(s):  
Luminita Confederat ◽  
Iuliana Motrescu ◽  
Sandra Constantin ◽  
Florentina Lupascu ◽  
Lenuta Profire
Keyword(s):  
Drug Delivery ◽  
Drug Delivery Systems ◽  
Average Diameter ◽  
Delivery Systems ◽  
Cross Linking ◽  
Low Molecular Weight ◽  
Polymeric Systems ◽  
Chitosan Microparticles ◽  
Degree Of Swelling

The aim of this study was to optimize the method used for obtaining microparticles based on chitosan � a biocompatible, biodegradable, and nontoxic polymer, and to characterize the developed systems. Chitosan microparticles, as drug delivery systems were obtained by inotropic gelation method using pentasodiumtripolyphosphate (TPP) as cross-linking agent. Chitosan with low molecular weight (CSLMW) in concentration which ranged between 0.5 and 5 %, was used while the concentration of cross-linking agent ranged between 1 and 5%. The characterization of the microparticles in terms of shape, uniformity and adhesion was performed in solution and dried state. The size of the microparticles and the degree of swelling were also determined. The structure and the morphology of the developed polymeric systems were analyzed by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM).The average diameter of the chitosan microparticles was around 522 �m. The most stable microparticles were obtained using CSLMW 1% and TPP 2% or CSLMW 0.75%and TPP 1%. The micropaticles were spherical, uniform and without flattening. Using CSLMW in concentration of 0.5 % poorly cross-linked and crushed microparticles have been obtained at all TPP concentrations. By optimization of the method, stable chitosan-based micropaticles were obtained which will be used to develop controlled release systems for drug delivery.

Synthesis and 31 P NMR characterization of new low toxic highly sensitive pH probes designed for in vivo acidic pH studies

2002 ◽  
Vol 10 (5) ◽  
pp. 1451-1458 ◽  
Author(s):  
Sophie Martel ◽  
Jean-Louis Clément ◽  
Agnès Muller ◽  
Marcel Culcasi ◽  
Sylvia Pietri
Keyword(s):  
Acidic Ph ◽  
Highly Sensitive ◽  
Nmr Characterization ◽  
Low Toxic ◽  
Ph Probes

scholarly journals Shiga Toxin (Stx)-Binding Glycosphingolipids of Primary Human Renal Cortical Epithelial Cells (pHRCEpiCs) and Stx-Mediated Cytotoxicity

Toxins ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 139
Author(s):  
Johanna Detzner ◽  
Elisabeth Krojnewski ◽  
Gottfried Pohlentz ◽  
Daniel Steil ◽  
Hans-Ulrich Humpf ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Epithelial Cells ◽  
Shiga Toxin ◽  
Saturated Fatty Acids ◽  
Human Kidney ◽  
Enterohemorrhagic Escherichia Coli ◽  
Highly Sensitive ◽  
Liquid Ordered ◽  
Uremic Syndrome

Human kidney epithelial cells are supposed to be directly involved in the pathogenesis of the hemolytic–uremic syndrome (HUS) caused by Shiga toxin (Stx)-producing enterohemorrhagic Escherichia coli (EHEC). The characterization of the major and minor Stx-binding glycosphingolipids (GSLs) globotriaosylceramide (Gb3Cer) and globotetraosylceramide (Gb4Cer), respectively, of primary human renal cortical epithelial cells (pHRCEpiCs) revealed GSLs with Cer (d18:1, C16:0), Cer (d18:1, C22:0), and Cer (d18:1, C24:1/C24:0) as the dominant lipoforms. Using detergent-resistant membranes (DRMs) and non-DRMs, Gb3Cer and Gb4Cer prevailed in the DRM fractions, suggesting their association with microdomains in the liquid-ordered membrane phase. A preference of Gb3Cer and Gb4Cer endowed with C24:0 fatty acid accompanied by minor monounsaturated C24:1-harboring counterparts was observed in DRMs, whereas the C24:1 fatty acid increased in relation to the saturated equivalents in non-DRMs. A shift of the dominant phospholipid phosphatidylcholine with saturated fatty acids in the DRM to unsaturated species in the non-DRM fractions correlated with the GSL distribution. Cytotoxicity assays gave a moderate susceptibility of pHRCEpiCs to the Stx1a and Stx2a subtypes when compared to highly sensitive Vero-B4 cells. The results indicate that presence of Stx-binding GSLs per se and preferred occurrence in microdomains do not necessarily lead to a high cellular susceptibility towards Stx.

scholarly journals Toward Physicochemical and Rheological Characterization of Different Injectable Hyaluronic Acid Dermal Fillers Cross-Linked with Polyethylene Glycol Diglycidyl Ether

Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 948
Author(s):  
Nicola Zerbinati ◽  
Sabrina Sommatis ◽  
Cristina Maccario ◽  
Maria Chiara Capillo ◽  
Giulia Grimaldi ◽  
...  
Keyword(s):  
Hyaluronic Acid ◽  
Polyethylene Glycol ◽  
Biological Activities ◽  
Diglycidyl Ether ◽  
Dermal Filler ◽  
Cross Linking ◽  
Matrix Structure ◽  
Dermal Fillers ◽  
Rheological Characterization

(1) Background: Injectable hyaluronic acid (HA) dermal fillers are used to restore volume, hydration and skin tone in aesthetic medicine. HA fillers differ from each other due to their cross-linking technologies, with the aim to increase mechanical and biological activities. One of the most recent and promising cross-linkers is polyethylene glycol diglycidyl ether (PEGDE), used by the company Matex Lab S.p.A., (Brindisi, Italy) to create the HA dermal filler PEGDE family. Over the last few years, several studies have been performed to investigate the biocompatibility and biodegradability of these formulations, but little information is available regarding their matrix structure, rheological and physicochemical properties related to their cross-linking technologies, the HA content or the degree of cross-linking. (2) Methods: Seven different injectable HA hydrogels were subjected to optical microscopic examination, cohesivity evaluation and rheological characterization in order to investigate their behavior. (3) Results: The analyzed cross-linked dermal fillers showed a fibrous “spiderweb-like” matrix structure, with each medical device presenting different and peculiar rheological features. Except for HA non cross-linked hydrogel 18 mg/mL, all showed an elastic and cohesive profile. (4) Conclusions: The comparative analysis with other literature works makes a preliminary characterization of these injectable medical devices possible.

scholarly journals Characterization of swelling behavior of carbon nano-filler modified polydimethylsiloxane composites

2021 ◽  
pp. 009524432110061
Author(s):  
Bo Yang ◽  
Balakrishnan Nagarajan ◽  
Pierre Mertiny
Keyword(s):  
Digital Image Analysis ◽  
Swelling Behavior ◽  
Optical Measurements ◽  
Natural Phenomenon ◽  
Cross Linking ◽  
Dimensional Changes ◽  
Experimental Findings ◽  
Carbon Based

Polymers may absorb fluids from their surroundings via the natural phenomenon of swelling. Dimensional changes due to swelling can affect the function of polymer components, such as in the case of seals, microfluidic components and electromechanical sensors. An understanding of the swelling behavior of polymers and means for controlling it can improve the design of polymer components, for example, for the previously mentioned applications. Carbon-based fillers have risen in popularity to be used for the property enhancement of resulting polymer composites. The present investigation focuses on the effects of three carbon-based nano-fillers (graphene nano-platelets, carbon black, and graphene nano-scrolls) on the dimensional changes of polydimethylsiloxane composites due to swelling when immersed in certain organic solvents. For this study, a facile and expedient methodology comprised of optical measurements in conjunction with digital image analysis was developed as the primary experimental technique to quantify swelling dimensional changes of the prepared composites. Other experimental techniques assessed polymer cross-linking densities and elastic mechanical properties of the various materials. The study revealed that the addition of certain carbon-based nano-fillers increased the overall swelling of the composites. The extent of swelling further depended on the organic solvent in which the composites were immersed in. Experimental findings are contrasted with published models for swelling prediction, and the role of filler morphology on swelling behavior is discussed.

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