Reply: increased axonal regeneration through a biodegradable amnionic tube nerve conduit.
Explore the source record for details and available documents.
Absorbable Implants↗
Biomedical subjects
J Mohammad
Publications and source records attributed to J Mohammad.
Modulation of peripheral nerve regeneration: a tissue-engineering approach. The role of amnion tube nerve conduit across a 1-centimeter nerve gap.
A new type of a biodegradable nerve graft conduit material, the amnion tube, has been developed in our laboratory. To test the tube in the peripheral nerve regeneration process, it was initially applied across a 1-cm sciatic nerve gap in rats and was compared with other nerve conduit materials. We used male Sprague-Dawley rats as our animal model. The experiment included 66 rats that were randomly assigned into five groups: autograft (n = 17), amnion tube (n = 19), silicone tube (n = 20), no repair (n = 7), and sham group (n = 3). The process of peripheral nerve regeneration was evaluated at 2, 4, 10, and 17 weeks following injury and repair by using morphologic and functional assessments of the outcome of nerve regeneration in each animal. Nerve regeneration across the amnion tube nerve conduit was comparable with that seen in autograft and superior to that of the silicone group. A uniform nerve tissue was seen filling and crossing the amnion conduit, and the regenerated nerve from the proximal stump reached the distal end and was undifferentiated from the normal nerve tissues. At 4 months, the amnion tube biodegraded and no longer could be identified and differentiated from the nerve tissues. The amnion tube animal group showed a number of axons very close to that in the nerve autograft group (37,157 versus 33,054). Functional recovery at a 2- to 4-week interval was significantly statistically higher only in the amnion tube animal group (p = 0.01). However, the improvement disappeared between 10 and 17 weeks. In conclusion, the amnion tube is a potential ideal nerve conduit material secondary to its unique characteristics: it contains important neurotropic factors, is biodegradable, provokes a very weak immune response, is semiflexible, is readily available, and is easily manufactured into different sizes and diameters.
Amnion↗
New polymer-based prepacked column for the reversed-phase liquid chromatographic separation of peptides over the pH range 2-12.
The aim of this paper was to investigate the properties of a new column, Source 5RPC, for the separation of peptides at pH 2, 4.5, 7, 9 and 12 and to compare this product with similar polymer-based products available on the market. All columns were prepacked with 5 microm polystyrene-divinylbenzene polymer bead matrices and had dimensions of 150x4.6 mm I.D. Separations of angiotensin peptides were achieved on these columns using different equilibration solvents in the pH range 2-12 and elution with acetonitrile gradients. The separation of the peptide mixture obtained on Source 5RPC column was compared with that of two other commercially available polymer-based matrices. Method scouting and optimisation were carried out using the novel chromatography system, AKTA purifier.
Angiotensins↗
Myelin basic protein purified on an ion-exchange continuous polymer bed in the presence of ethylene glycol and salt possesses activity against p-nitrophenyl acetate.
In this paper we describe a fast and mild method based on the use of a unique cation exchanger and buffers containing ethylene glycol and salt for the purification of the myelin basic protein (MBP; MW 18.5 kDa). MBP thus purified hydrolyses catalytically p-nitrophenyl acetate. This esterase activity facilitates not only the purification of MBP but also indicates that probably it is in its native state, i.e. there is a good chance that the purified molecules are structurally and chemically identical. This is a prerequisite to obtain crystals appropriate for x-ray diffraction and other studies.
4-Nitrophenylphosphatase↗
Continuous beds for microchromatography: cation-exchange chromatography.
Microcolumns (i.d. 10-320 microns) for cation-exchange chromatography can be prepared simply by polymerization of an aqueous solution of appropriate monomers, including the desired ligand, directly in the chromatographic tube (fused-silica tubing) in the presence of salt. The beds thus prepared are in the form of rods traversed by channels through which the eluent can pass. The walls of the channels are composed of very small particles and are impermeable to peptides and proteins, which is important for rapid mass transfer and thus for high resolution at high flow rates. The bed becomes attached covalently to the tube wall during synthesis. A complicated column tube design with a supporting frit at the bottom is thus eliminated. The absence of a frit reduces the flow resistance and facilitates interfacing to mass spectrometers. The covalent linkage of the bed to the tube wall also serves to suppress the zone-broadening "wall effect." A homogeneous "packing" of a continuous bed column with an inner diameter as small as 10 microns is easily obtained. The resolution, binding capacity, and flow rate (i.e., run time at a given pressure) can be varied by changing the composition of the monomer solution. One can thus tailor the beds to each separation problem. The chromatographic properties of the microcolumns are demonstrated by separations of model proteins.
Chromatography, Ion Exchange↗
A simple and inexpensive chromatographic method for the purification of gamma-globulin from human serum.
Inexpensive cation- and anion-exchangers based on continuous polymer beds were prepared directly in a plastic syringe. These beds are unique in the sense that they are synthesized by a very simple and cost-effective procedure; for instance, no preparation of beads is required as in conventional methods. Highly purified gamma-globulin could be prepared easily by step-wise elution accomplished by forcing buffers of increasing salt concentration through the column with the aid of the plunger.
Chromatography, Ion Exchange↗
Real-time kinetic analysis of limited proteolysis by ion-exchange chromatography using compressed, non-porous agarose beads.
In biotechnology there is a great need for methods that can be used for kinetic studies of ongoing processes, such as limited proteolysis. Ion-exchange chromatography on a nonporous, compressed agarose matrix was used in the study presented in this paper to monitor papain cleavage of fungal cellulases. This non-porous matrix allows completion of a chromatographic analysis, with baseline resolution, within 30-60 s. Utilizing this very fast chromatographic method one can monitor a proteolysis 'continuously' by repeated chromatographic analysis of the incubation mixture and, if desired, terminate it at the optimal moment. Fractions were also collected for identification by activity assays and analytical SDS-PAGE.
Cellulase↗
Continuous beds. Their applicability for immobilization of proteins.
An epoxy-activated continuous bed can be prepared for immobilization of proteins in a simple, rapid, and cost-effective way. The concentration of epoxy groups on the continuous bed was as high as 600 mumol/mL compressed bed (compression of the bed decreases the peak broadening). Human transferrin, human serum albumin and particularly urease were employed as model proteins. The immobilization of urease was virtually completed within 1 h in 1 M potassium phosphate, pH 7.4. The binding capacity was 97 mg of urease/mL compressed bed. This bed is of clinical interest, since it is inexpensive to prepare and permits reproducible enzymatic determination of urea in serum and urine (the chromatographic step is finished within 1-2 min).
Chromatography, High Pressure Liquid↗
Dye-ligand affinity chromatography on continuous beds.
Continuous beds derivatized with three triazine dyes (Cibacron Blue 3G-A, Pricon Red HE-3B and Pricon Red H-3B) were used for chromatographic purification of dehydrogenases from yeast enzyme concentrate. All three columns, which were prepared by a very simple and cost-effective method, provided strong binding of glucose-6-phosphate dehydrogenase and lactate dehydrogenase. The Cibacron Blue 3G-A column showed high affinity for alcohol dehydrogenase. Under the same conditions, the Pricon Red HE-3B column showed a lower affinity and the Pricon Red H-3B column showed none. The adsorbed dehydrogenases were eluted specifically from the columns in high yields (71-113% by desorption with the coenzymes NADP, NADH and NAD respectively). Non-specific binding of human serum albumin and transferrin to these columns was also investigated. Enzyme assays and analyses by capillary electrophoresis showed that the continuous beds derivatized with triazine dyes gave a high degree of purification.
Alcohol Dehydrogenase↗