Dietary cholestyramine reduces ochratoxin A-induced nephrotoxicity in the rat by decreasing plasma levels and enhancing fecal excretion of the toxin

Ochratoxin A (OTA) is a mycotoxin that may contaminate animal feed (oat, barley, and rye) and food (wheat, rice, coffee, beer, pig meat), leading to major health problems (e.g., nephropathy) in several animal species including humans. Several methods have been tested to reduce the toxicity of OTA in animals but with limited success. In rats, the effect of cholestyramine (CHA), a bile acid-binding resin, was investigated on OTA-induced nephrotoxicity and bioavailability. Animals were fed semisynthetic diets containing two levels of OTA: 1 or 3 ppm. At each level of OTA, the diets were enriched with 0.1, 1, and 5% of CHA. The results showed that CHA decreased the concentration of OTA in plasma. At 1 and 3 ppm of OTA in the diet, CHA is effective at a level of 0.1% and 5%, respectively. The excretion of OTA and its metabolites (ochratoxin alpha and hydroxylated ochratoxin A) in bile and urine was also decreased by addition of 5% CHA in the diet. This was associated with an increase of OTA excretion in feces. Enzymuria and renal morphology revealed that dietary CHA can decrease OTA-induced nephrotoxicity, probably by reducing renal exposure to the toxin. In conclusion, CHA can reduce OTA concentrations in plasma as well as reducing nephrotoxicity, which may be attributed to a decrease of bioavailability and/or enterohepatic circulation of the toxin.     

1,4-Cyclohexanecarboxylates: potent and selective inhibitors of phosophodiesterase 4 for the treatment of asthma

Evaluation of a variety of PDE4 inhibitors in a series of cellular and in vivo assays suggested a strategy to improve the therapeutic index of PDE4 inhibitors by increasing their selectivity for the ability to inhibit PDE4 catalytic activity versus the ability to compete for high affinity [3H]rolipram-binding sites in the central nervous system. Use of this strategy led ultimately to the identification of cis-4-cyano-4-[3-(cyclopentyloxy)-4-methoxyphenyl]cyclohexane-1-carboxyl ic acid (1, SB 207499, Ariflo), a potent second-generation inhibitor of PDE4 with a decreased potential for side effects versus the archetypic first generation inhibitor, (R)-rolipram.     

Visualization of specific B and T lymphocyte interactions in the lymph node

Early events in the humoral immune response were visualized in lymph nodes by simultaneous tracking of antigen-specific CD4 T and B cells after immunization. The T cells were initially activated in the T cell areas when the B cells were still randomly dispersed in the B cell-rich follicles. Both populations then migrated to the edges of the follicles and interacted there, resulting in CD154-dependent B cell proliferation and germinal center formation. These results provide visual documentation of cognate T-B cell interactions and localize them to the follicular border.     

Severe aortic regurgitation with mechanical prosthetic valve replacement in pauciarticular juvenile rheumatoid arthritis

We describe a patient with pauciarticular juvenile rheumatoid arthritis with aortic insufficiency who underwent successful aortic valve replacement with a mechanical prosthetic valve.     

Complexation Behavior of Polyampholytes and Charged Objects

We study theoretically the interaction of a polyampholyte chain with charged planes, cylinders, and spheres. Due to the random character of the charge distribution along the chain, a polyampholyte possesses a spontaneous dipole moment, which can interact favorably with charged objects. Depending on the charge strength of the object and the polyampholyte length and fraction of charged monomers, this attractive interaction can be strong enough to induce adsorption. The addition of salt weakens the trend to adsorption, but proves necessary to adsorb polyampholytes of the same net charge as the charged object in the case of planes and cylinders. Long polyampholytes form globules, for which the number of uncompensated charges and thus the spontaneous dipole moment is reduced. Nevertheless, globules can adsorb on charged objects via two pathways: they either adsorb as a whole, (intact globule), or they are dissolved into a coil state prior to adsorption. Applications to the complexation behavior of polyampholytes with stiff, rodlike polyelectrolytes and with charged microspheres or charged spherical micelles are given.     

Isolation and stability of histidine-tagged proteins produced in plants via potyvirus gene vectors

A system for the expression and purification of histidine-tagged proteins from plants has been developed using a tobacco etch potyvirus (TEV)-derived gene vectors. The vectors offered a convenient polylinker and a choice of histidine tagging at the recombinant proteins' N or C termini. These vectors were utilized for expression of proteins encoded by beet yellows closterovirus (BYV). Approximately 4 micrograms/g of 20-kDa BYV protein was readily isolated from plants systemically infected by hybrid TEV. In contrast, only minute quantities of 22-kDa BYV capsid protein (CP) histidine-tagged at its N or C terminus could be purified. Rapid degradation of the recombinant CP has been implicated in its failure to accumulate in infected plants. Fusion with TEV HC-Pro stabilized the histidine-tagged BYV CP and facilitated purification of the fusion product from infected plants. This same fusion approach was successfully used with the 24-kDa minor BYV CP. The recombinant proteins were recognized by histidine-tag-specific monoclonal antibody in immunoblot analysis. These results demonstrate the utility of a designed series of TEV vectors for expression, detection, and purification of the recombinant proteins and suggest that intrinsic protein stability is a major factor in a recovery of recombinant proteins from plants.     

Autocrine inhibition of the epidermal growth factor receptor by intracellular expression of a single-chain antibody

A gene encoding a single-chain antibody which specifically binds the human epidermal growth factor (EGF) receptor has been constructed and expressed intracellularly. The single-chain antibody is derived from monoclonal antibody 225 which competes with EGF for binding to the extracellular domain of the receptor. The single-chain antibody was provided with a signal peptide to direct it to the secretory pathway and was expressed in EGF receptor transformed NIH/3T3 fibroblasts. EGF induced activation of its receptor was reduced in these cells. In addition, EGF-induced anchorage-independent growth of the cells was inhibited. The data suggest that the single-chain antibody functions in an autocrine fashion to inhibit the activity of the EGF receptor.     

Follow-up of argon laser trabeculoplasty: is a day-one postoperative IOP check necessary?

BACKGROUND AND OBJECTIVES: To evaluate the benefit of measuring the intraocular pressure (IOP) on the first postoperative day after argon laser trabeculoplasty (ALT). PATIENTS AND METHODS: We retrospectively reviewed 407 ALT procedures with perioperative apraclonidine performed on 226 patients between January 1991 and December 1993. Data analyzed included type of glaucoma, extent of treatment, whether the procedure was initial or repeat, laser parameters, and IOP preoperatively and at 1 hour, 1 day, and 1 month postoperatively. RESULTS: The percentage of patients with an IOP rise of greater than 3 mm Hg at 1 hour, 1 day, and 1 month following ALT was 11.3%, 4.2%, and 5.2% respectively. The incidence of IOP elevations greater than 10 mm Hg was 2.2%, 1.0%, and 1.5% at 1 hour, 1 day and 1 month, respectively. Of 17 cases with an IOP elevation greater than 3 mm Hg at 1 day, four eventually required a trabeculectomy. However, there were no consistent factors that distinguished which cases with elevated IOP at 1 day ultimately needed further therapy, nor did the 1-day postoperative examination predict which patients would have IOP elevation at 1 month. CONCLUSION: IOP 1 day after ALT is rarely elevated and does not correlate with IOP elevation at 1 month. Therefore, an IOP check at 1 day is not felt to be necessary for most patients.