Isolated Castleman disease of the neck: MR findings.

Castleman disease in an 11-year-old girl appeared as a neck mass that grew despite antibiotic treatment. MR showed a well-defined solid mass, isointense with muscle on short-repetition-time/short-echo-time images, with a stellate area of central hypointensity on long-repetition-time/long-echo-time images, that did not enhance with gadolinium.     

Post-keratoplasty corneal ulcers and bandage lenses

285 cases of penetrating keratoplasty in whom hydrophilic bandage lenses were fitted were analyzed for the occurrence of corneal ulcers. Of these eyes 26 developed culture-proven bacterial ulcers. No correlation could be made between any particular type of contact lens and the development of corneal ulcer. Although no single factor could be delineated which may be responsible for this problem, this risk appears to be escalated where host defense mechanisms are impaired. The clinician should recognize the potential risk in using bandage lenses when the cornea is immunosuppressed and completely denervated.     

Reaction of dithiothreitol and para-nitroacetophenone with different radical precursors of .OH radical-induced strand break formation of single-stranded DNA in anoxic aqueous solution.

The yields of single-strand breakage (ssb) in single-stranded calf thymus DNA (ssDNA) have been determined after 60Co gamma-irradiation of aqueous anoxic solutions in the presence of different concentrations of dithiothreitol (DTT), ascorbate or trans-4,5-dihydroxy-1,2-dithiane, using low-angle laser light scattering. The influence of DTT on the kinetics of ssb formation has been determined by conductivity measurements in pulse radiolysis. The results suggest that strand breakage in ssDNA proceeds via two modes of about equal contribution and with half-lives of about 7 ms and 0.8s, respectively. Both modes reflect reactions of at least two DNA radicals, which react with DTT by hydrogen-atom transfer reactions with similar rate constants of about 5-9 x 10(5) dm3 mol-1 s-1. These hydrogen-atom transfer reactions inhibit strand break formation. The slow mode is shown to represent the decay of base-radicals to generate sugar radicals. The involvement of the oxidizing .OH adduct radical of guanine in the formation of strand breaks can be ruled out and there is no evidence for a contribution from the anion or radical anion of DTT to the inhibition of strand breaks via electron transfer reactions to DNA radicals.     

Interaction of calmodulin with iodothyronines: effect of iodothyronines on the calmodulin activation of cyclic AMP phosphodiesterase

The interaction between calmodulin and iodothyronines and the effect of iodothyronines on the calmodulin activation of cyclic AMP phosphodiesterase were investigated. Binding of [L-125I]triiodothyronine to calmodulin from pig brain, studied by equilibrium dialysis, was dependent on Ca2+, was saturable and reversible, with an apparent Kd of 2.79 microM and binding capacity of 0.5 nmol/20 micrograms of calmodulin L- and D-thyroxine, D-triiodothyronine and tetrac displaced [L-125I]triiodothyronine at concentrations of 8-10 microM; triac, 3,3'-diiodothyronine and reverse-triiodothyronine were weak displacers. In the presence of the antipsychotic drug trifluoperazine, binding decreased in a dose-related manner. Ultraviolet irradiation of calmodulin in the presence of trifluoperazine reduced the binding of [L-125I]triiodothyronine to calmodulin irreversibly. Calmodulin activation of cyclic AMP phosphodiesterase decreased when iodothyronines were bound to calmodulin; the calmodulin-L-triiodothyronine complex was the most active among the stereoisomers of thyroxine and triiodothyronine. These results suggest that, when triiodothyronine was bound to Ca2+-calmodulin, the activation of cyclic AMP phosphodiesterase by the latter is suppressed.     

Hypoglycemic effect of gelatin microspheres with entrapped insulin and protease inhibitor in normal and diabetic rats

Insulin containing gelatin microspheres (IGM) with and without soyabean trypsin inhibitor (TI) were pre-pared and coated with enteric polymers to protect them from degradation in stomach and to release the insulin upon reaching the intestine. Four types of coated IGM were prepared: (i) IGM coated with natural polymers (chitosan inner coat-alginate outer coat), (ii) IGM-TI coated with cellulose acetate phthalate; (iii) IGM-TI coated with cellulose acetate butyrate, and (iv) IGM-TI coated with natural polymers (chitosan inner coat-alginate outer coat). The protective efficiency of uncoated and four types of coated microspheres to-ward digestive enzymes such as pepsin and trypsin was evaluated under simulated physiological conditions. The microspheres were characterized for their insulin content and particle size. The morphology of the micro-spheres was studied using scanning electron micros-copy. The in vitro release studies of insulin from uncoated and coated microspheres indicated that the release followed a zero-order pattern, prolonging for 6 days from 2 days in the case of uncoated spheres. The uncoated and coated microspheres containing insulin (20 IU/kg) were orally administered to albino Wistar rats by stomach tube, and insulin absorption was evaluated by assessing the hypoglycemic effect in normal and diabetic rats. A significant and continuous hypoglycemic effect was observed in diabetic rats following oral administration of coated IGM containing TI when compared to the effect following administration of coated IGM without TI.     

Stimulation of DNA synthesis by rat plasma following in vivo treatment with three liver mitogens.

The present study was undertaken to determine the effect of two different types of liver cell proliferative stimuli, namely compensatory regeneration and direct hyperplasia on DNA synthesis of normal and preneoplastic isolated hepatocytes. Platelet-poor plasma (PPP) isolated from male Wistar rats treated with three different hepato-mitogens, lead nitrate (LN), cyproterone acetate (CPA) and ethylene dibromide (EDB), or subjected to surgical partial hepatectomy (PH), was tested for its ability to stimulate DNA synthesis in normal and preneoplastic hepatocytes in primary cultures. Induction of DNA synthesis was detected as early as 30 min after CPA, EDB and PH administration and persisted up to 5 days after the LN administration. In addition, hepatocytes isolated from preneoplastic liver nodules were also able to respond in culture to the DNA synthesis stimulus induced by these factors.