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Biomedical subjects

J Martens

Publications and source records attributed to J Martens.

50 records · Page 3Linked to original sources
PubMed1981

The effect of plasma exchange on synovitis in rheumatoid arthritis.

Eight patients with a severe exacerbation of rheumatoid arthritis were treated by twice weekly plasma-exchange for 3 weeks in order to evaluate the effect of plasma-exchange on synovitis. During the plasma-exchange period, patients remained on the drug regimen they were on at admission to the hospital. Plasma was replaced isovolemically with human, purified plasma protein fraction. Improvement in clinical parameters of synovitis and serological parameters of inflammation occurred in almost all patients. After 6 months the clinical remissions were sustained. Three patients experienced a rebound synovitis and one patient a rebound vasculitis at the end of or just after the plasma-exchange period. The rebound phenomena were moderate and of short duration. Plasma-exchange may exert its beneficial effects by depleting important mediators of injury such a complement fibrinogen and circulating immune complexes, by improving reticuloendothelial function, and by increasing the drug response of the inflammatory target tissue. The role of depletion of circulating immune complexes was not so clear in this study. It is concluded that limited plasma-exchange is an effective means to induce a symptomatic improvement in an acute exacerbation of polyarthritis, without changing the basic therapy and thus avoiding corticosteroid dependency.

Adult↗
PubMed1980

Methods for the study of leaf anatomy in palms.

Large size, hardness, combinations of thick-walled fibers and sclereids with thin-walled parenchyma cells, and the occurrence of silica, calcium oxalate, and tannins make anatomical preparations of palm leaves difficult. Samples for anatomical study should encompass one-half a pinna or a comparable portion from palmate and entire leaves including the midrib, all large ribs, and the margin. Similar pieces from herbarium specimens are reconstituted in glycerin alcohol, aerosol OT and distilled water (10:3:90). All samples are fixed in formol-acetic-alcohol (FAA) but stored in glycerin alcohol to minimize hardening. Transverse and longitudinal sections 15 microns thick, epidermal macerations, and pieces for clearing and for scanning electron microscopy are prepared from the FAA fixed material. Samples for electroscanning are gradually changed to 100% acetone, critical point dried with CO2, and coated with 100-300 angstroms of gold. Leaf material for microtomy is treated with hydrofluoric acid, embedded in Paraplast, and sectioned at 15 microns at a temperature of 7.2 C. Paraplast sections are floated directly on a modification of Sass' Adhesive III, mounted unstained or stained in safranin and fast gaee, and observed in polarized light. Epidermal peels are prepared by soaking pieces 5 mm square for 12-24 hours in undiluted bleach. Pieces for observation of transverse veins are cleared by treatment in 5% sodium hydroxide in a 60 C oven, washed rapidly in three changes of distilled water, and placed in one-third strength commercial bleach until clear. The same procedures can be used to prepare reproductive material for anatomical observations, but time schedules must be increased for larger specimens.

Botany↗
PubMedDate not supplied

Direct resolution of enantiomers by impregnated TLC.

Direct resolution of enantiomers has acquired greater analytical importance. Of various chromatographic techniques, TLC continues to enjoy considerable reputation for the purpose. The present paper deals with an important and yet less explored aspect of TLC i.e. impregnation. Methods of impregnation of thin layer material with a variety of reagents and the role of impregnating reagents in resolving compounds on these layers, with special reference to main/basic approaches of impregnation as applied to direct enantiomeric resolution, are discussed.

Amino Acids↗
PubMedDate not supplied

TLC resolution of enantiomers of amino acids and dansyl derivatives using (1R,3R,5R)-2-azabicyclo[3,3,0]octan-3-carboxylic acid as impregnating reagent.

The enantiomeric resolution of certain amino acids and some of their dansyl derivatives was achieved on thin silica gel plates impregnated with (1R,3R,5R)- 2-Azabicyclo[3,3,0]octan-3-carboxylic acid, which is an industrial waste material, and a proline analogue non proteinogenic alpha-amino acid. Different combination of 0.5 M NaCl-MeCN were found to be successful in resolving dansyl-DL-amino acids; addition of methanol was required in some cases. Spots were visualised using a fixed wavelength (254 nm) ultraviolet chamber. Resolution of DL-amino acids was successful in different combinations of MeCN-MeOH-H2O and detection was made with ninhydrin (0.2% in acetone).

Amino Acids↗
PubMedDate not supplied

Resolution of enantiomers of ibuprofen by liquid chromatography: a review.

Ibuprofen is one of the most effective and widely used non-steroidal analgesic and anti-inflammatory agent. It is marketed as a racemic mixture though it is known that the pharmacological activity resides in the (S)-(+)-enantiomer only. Several direct/indirect liquid chromatographic methods involving a variety of chiral/achiral phases along with their possible role in resolution, chiral and achiral agents used for derivatisation have been discussed with special reference to ibuprofen, and mentioning their application to the resolution of other 2-aryl-propionic acids/profens.

Anti-Inflammatory Agents, Non-Steroidal↗