Single drop impact of liquid on a static powder bed was studied to investigate the granule formation mechanism, droplet penetration time, as well as the characterization of granules (morphology, surface structure and internal structure). Water was used as the liquid and two pharmaceutical powders, microcrystalline cellulose (MCC) and acetaminophen (APAP), were mixed to make heterogeneous powder beds. The complete drop impact and penetration was recorded by a high speed camera. Two granule formation mechanisms that have been identified previously occurred: Spreading and Tunneling. Spreading occurred for mixtures with an APAP amount of less than 20%, while Tunneling started to occur when the APAP amount increased above 20%. With an increase of APAP concentration, the mean particle size decreased, drop penetration time increased, and the granules formed became smaller in size, which was in good agreement with previous literature. The granule morphology, surface structure, and internal structure were characterized by a prism method with image analysis, scanning electron microscopy (SEM), and X-ray microtomography, respectively. The Spreading mechanism produced flat disks with a porous internal structure, while the Tunneling mechanism produced round granules with a dense internal structure. There is a clear trend of decreasing porosity and increasing roundness of granules made from heterogeneous mixtures within the transition from Spreading to Tunneling. It is believed that the mean particle size of the powder bed and the powder-liquid contact angle are the predominant factors in influencing the formation mechanism, drop penetration time, and granule properties.
The aim of this study was to investigate the protective effect of naringenin on oxidative stress, on proinflammatory cytokines like TGF-beta1, IL-1beta and on programmed cell death in the testicular damage resulting from streptozotocin (STZ) induced diabetes in rats. Diabetes was induced by a single intraperitoneal injection of STZ (50 mg/kg), and the rats were treated with naringenin (5 mg/kg and 10 mg/kg) administered once a day orally for 10 weeks, starting 3 days after the STZ injection. At the end of the study, all animals were sacrificed. Testis tissue and blood samples were collected for the assessment of sperm parameters, and for biochemical and histopathological analysis. Naringenin treatment significantly decreased the levels of elevated tissue TBARS (thio-barbituric acid) and increased the superoxide dismutase (SOD), catalase and glutathione peroxidase (GPx) enzyme activities in the testis tissues. The naringenin-treated rats in the diabetic group showed an improved histological appearance, sperm parameters, and serum testosterone levels, along with a decrement of terminal dUTP nick end-labeling (TUNEL) detected program cell death and a reduced over expression of TGF-beta1, IL-1beta in Sertoli cells and Leydig cells. These results suggest that naringenin is a food supplement potentially beneficial in reducing testicular damage in diabetic rats by decreasing the oxidative stress related to programmed cell death.
- MeSH
- Estrogen Antagonists administration & dosage pharmacology MeSH
- Apoptosis drug effects MeSH
- Diabetes Mellitus, Experimental * drug therapy blood MeSH
- Flavanones * administration & dosage pharmacology MeSH
- Immunohistochemistry MeSH
- Interleukin-1beta MeSH
- Sperm Motility drug effects MeSH
- Oxidative Stress drug effects MeSH
- Sperm Count statistics & numerical data MeSH
- Rats, Wistar MeSH
- Microscopy, Scanning Tunneling MeSH
- Statistics as Topic MeSH
- Case-Control Studies MeSH
- Testis * enzymology immunology pathology MeSH
- Testosterone blood MeSH
- Transforming Growth Factor beta1 MeSH
- Germ Cells drug effects MeSH
- Animals MeSH
- Check Tag
- Male MeSH
- Animals MeSH
The reaction of α-amino-ω-methoxypoly(ethylene glycol) [M = 5000] or star α-amino-poly(ethylene glycol) [M = 20 000] with hemiesters of prednisolone dicarboxylic acids (succinic, glutaric, adipic, phthalic acid) has been used to prepare the corresponding conjugates. The rate of esterase catalyzed hydrolysis of the conjugates is controlled by the molecular mass of poly(ethylene glycol) and the length of the linker between prednisolone and poly(ethylene glycol) (τ(1/2)∼ 5-0.5 h). The enzymatic hydrolysis proceeds most rapidly at conjugates with linkers derived from adipic and phthalic acids. The synthesized conjugates form polypseudorotaxanes with α-cyclodextrin which were characterized by 2D NOESY NMR spectra, powder X-ray diffraction patterns and in one case also by STM microscopy. In the case of the polypseudorotaxane having the linker derived from adipic acid, the enzymatic release proceeds ca. five times slower in comparison with the rate of prednisolone release from the corresponding conjugate. The rate of prednisolone release from the carrier can be controlled by three factors: character of the linker between the polymeric carrier and prednisolone, the molecular mass of poly(ethylene glycol) and complex formation with α-cyclodextrin. The synthesized polypseudorotaxanes represent new promising transport systems intended for targeted release of prednisolone in transplanted liver.
- MeSH
- alpha-Cyclodextrins chemistry MeSH
- Cyclodextrins chemistry MeSH
- Molecular Structure MeSH
- Poloxamer chemistry MeSH
- Polyethylene Glycols chemistry MeSH
- Prednisolone chemistry MeSH
- Microscopy, Scanning Tunneling MeSH
- Rotaxanes chemistry MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
The conductivity of DNA covalently bonded to a gold surface was studied by means of the STM technique. Various single- and double-stranded 32-nucleotide-long DNA sequences were measured under ambient conditions so as to provide a better understanding of the complex process of charge-carrier transport in natural as well as chemically modified DNA molecules. The investigations focused on the role of several features of DNA structure, namely the role of the negative charge at the backbone phosphate group and the related complex effects of counterions, and of the stacking interactions between the bases in Watson-Crick and other types of base pairs. The measurements have indicated that the best conductor is DNA in its biologically most relevant double-stranded form with Watson-Crick base pairs and charged phosphates equilibrated with counterions and water. All the studied modifications, including DNA with non-Watson-Crick base pairs, the abasic form, and especially the form with phosphate charges eliminated by chemical modifications, lower the conductivity of natural DNA.
- MeSH
- DNA chemistry metabolism MeSH
- Electric Conductivity MeSH
- Financing, Organized MeSH
- Phosphates chemistry metabolism MeSH
- DNA, Single-Stranded chemistry MeSH
- Oligodeoxyribonucleotides chemistry metabolism MeSH
- Base Pairing MeSH
- Microscopy, Scanning Tunneling MeSH
- Base Sequence MeSH
- Hydrogen Bonding MeSH
- Gold chemistry MeSH
... Between Cells and Their Surrounding Media Must Be Increased for Good Observations 49 Dark-field Microscopy ... ... Highlights Specimens Against a Dark Background 49 -- Fluorescence Microscopy Is Used to Examine Materials ... ... The Electron Microscope Can Resolve Objects a Thousand Times Better than the Light Microscope 49 Scanning ... ... Electron Microscope Allows a Three-dimensional View of the Object 51 -- The Scanning Tunneling Microscope ...
XXVIII, 812 s. : il. ; 32 cm
