Sarcoidosis presenting as an enlarging solitary pulmonary nodule

Sarcoidosis is generally not considered in the differential diagnosis of solitary pulmonary nodules. We recently encountered a case in which preoperative awareness of this presentation of sarcoidosis allowed a limited pulmonary resection with resultant lower morbidity and potential preservation of lung function to be performed. Although rare, sarcoidosis should be considered in the differential diagnosis of solitary pulmonary nodules.     

Maturational changes in CYP2D16 expression and xenobiotic metabolism in adrenal glands from male and female guinea pigs.

CYP2D16 is expressed at high levels in the zona reticularis (ZR) of guinea pig adrenal glands and contributes to adrenal metabolism of xenobiotics. Studies were done to evaluate the effects of age and gender on adrenal CYP2D16 expression and xenobiotic metabolism. In both male and female guinea pigs at 1, 7, 14, or 30 weeks of age, in situ hybridization and immunohistochemistry confirmed that CYP2D16 was highly localized to the ZR of the adrenal gland. The steroidogenic P450 isozyme, CYP17, by contrast, was expressed in both the zona fasciculata and ZR. The intensity of CYP2D16 staining was not age- or gender-dependent. However, the proportion of each adrenal gland comprised by ZR and thus expressing CYP2D16 increased with aging in both sexes and was greater in males than in females. The rates of metabolism of bufuralol, a CYP2D-selective substrate, by adrenal microsomal preparations generally correlated with the amount of ZR (and CYP2D16) in the gland. Thus, adrenal xenobiotic-metabolizing activities were greater in males than in females at all ages and increased with aging in males. However, the rates of bufuralol metabolism declined in sexually mature females (14 weeks) from the levels found in prepubertal females (7 weeks) and then increased markedly in retired breeders (30 weeks), suggesting an inhibitory effect of estrogens on enzyme activity. The results indicate that the age and gender differences in adrenal CYP2D16 content are largely determined by differences in the size of the ZR rather than the concentrations of CYP2D16 within cells of the ZR. However, adrenal xenobiotic-metabolizing activities in females seem to be further modulated by an inhibitory effect of estrogens.     

Physical characterization of thin semi-porous poly(L-lactic acid)/poly(ethylene glycol) membranes for tissue engineering

This study examines physical properties of solvent-cast poly(L-lactic acid) (PLLA): poly(ethylene glycol) PEG membranes as a function of PEG molecular weight (MW) and incubation in vitro for 6 weeks. PEGs of MW 400, 1450 and 8000 were used. The morphological, thermal, mechanical and permeability properties of the membranes were studied prior to and after 3 and 6 weeks of incubation in phosphate-buffered saline (PBS) at 37 degrees C. The membranes showed a thickness of about 35+/-5 microm and were found to be semi-porous, with a non-porous surface as well as a porous surface with pore-diameters of 0.5-5 microm. The surface pore size was found to be a function of PEG MW used. All membranes were mechanically strong, with elastic moduli and tensile strength of 150-440 MPa and 7-36 MPa, respectively, all through the 6-week incubation period. The lower-MW PEGs plasticized PLLA based on high initial percent elongation; however, the effect was lost after 3 weeks of incubation in PBS. All membranes except those fabricated with PEG 8000 were impermeable for up to 6 weeks of incubation in PBS. Permeability studies showed that only PLLA:PEG 8000 membranes were permeable to methylene blue after 3 weeks of degradation.     

3H]ouabain binding during the monolayer organization and cell cycle in MDCK cells

The specific binding of [3H]ouabain in an epithelial cell line derived from a dog kidney (MDCK) was determined during epithelial reorganization and also during the cell cycle. In suspended cells, the specific binding of [3H]ouabain is reduced 67% compared with the binding obtained in a complete monolayer. After plating back these cells on a permeable support, both transepithelial electrical resistance and [3H]ouabain binding increase with time of incubation. [3H]ouabain binding decreases during S and G2 phases of the cell cycle to reach a minimum during mitosis and increases again during GI. The transepithelial electrical resistance, determined simultaneously, shows the same behavior. The reduction in the number of [3H]ouabain binding sites in two different circumstances in which the epithelial membrane organization is disrupted and the increase in [3H]ouabain binding sites when the epithelial membrane is reorganized are consistent with the hypothesis that the number of pumping sites responsible for the active step in the transepithelial active transport is additional to the number required to maintain the intracellular ionic composition.     

The chick embryo in toxicology: an alternative to the rabbit eye

The chorioallantoic membrane (CAM) of the chick embryo is readily accessible for experimentation. It is a complete tissue that responds to injury with classical inflammatory reactions. It is limited to the late phase of embryologic life, and is without the sense of pain. Focal topical application of various household products onto the CAM results in local injury and reactions that differ in severity from one product to another. For any single product, tested as a sequence of dilutions on a series of membranes, the CAM responds with decreasing intensity that parallels the decreasing dosage. The membrane is prepared for study according to the method of Zwilling (Transplantn Bull 1959, 6, 115). The test material is applied in a Teflon ring to the 14-day-old CAM, to localize the application site. The macroscopic response is scored on day 17 of incubation. The results of analysis of histological preparations are found to correlate with macroscopic appearance. When a series of preparations was ranked according to the severity of the response each induced on the CAM, there was a good correlation with the ranking of the same preparations in the Draize test.