Pathologic characteristics of resected squamous cell carcinoma of the trachea: prognostic factors based on an analysis of 59 cases

While squamous cell carcinoma (SCC) is the most common tracheal malignancy, few reports describe the pathologic considerations that may guide intraoperative decisions and prognostic assessment. We reviewed 59 tracheal SCC treated between 1985 and 2008 by segmental resection of the trachea, including resection of the carina in 24% and inferior larynx in 14%. We classified these tumors by grading histologic differentiation and microscopic features used in SCC of other sites. Of 59 tumors, 24% (14 of 59) were well differentiated, 49% (29 of 59) were moderately differentiated, and 27% (16 of 59) were poorly differentiated. Unfavorable prognostic factors were tumor extension into the thyroid gland (all of five so-afflicted patients died of tumor progression within 3 years) and lymphatic invasion (mean survival 4.6 versus 7.6 years). Keratinization, dyskeratosis, acantholysis, necrosis, and tumor thickness did not predict prognosis. As surgical resection is the only curative treatment; the surgeon should establish clean lines of resection using, as appropriate, intraoperative frozen section. The pathologist can provide additional important prognostic information, including tumor differentiation and extent, invasion of surgical margins, and extension into the thyroid.     

Assessment of the biocompatibility of photosensitive polyimide for implantable medical device use

Polyimides have been widely used for biosensor encapsulation and more recently as substrates for neural implants. They have excellent thermal stability, high chemical resistance, and can be prepared as thin, flexible films. Photosensitive polyimides present similar physical properties to polyimides, and have the advantage that they can be photo-lithographically patterned. However, to date little data on their biocompatibility has been reported. Two commercially available polyimides (PI) and one photo-sensitive polyimide (PSPI) were evaluated in vitro using the ISO 10993 standard on biocompatibility. The materials were Dupont Kapton foil HN, HD Microsystem PI2611, and Fujifilm Durimide 7020 (PSPI). PI2611 and Durimide 7020 were spin-coated on silicon wafers, cured at temperatures ranging from 150 to 450 degrees C, and sterilized by autoclave. All materials were evaluated using a scanning electron microscope pre- and postcell culture. Cell viability was determined by an MTS assay. Their mechanical properties and stability during cell culture as a function of time and environment were investigated by nanoindentation. The MTS results show that PSPI is noncytotoxic compared with the negative control of polyethylene and the conventional PIs tested. Fibroblast adhesion, morphology, and spreading were good and better on the PSPI substrate than on the PI2611. Schwann cell appearance was similar on each of the PIs and the PSPI tested. The results suggest that PSPIs may have potential use for biological microsystem and neuroprosthetic applications.     

Division‐linked differentiation can account for CD8+ T‐cell phenotype in vivo

The CD8⁺ T‐cell response to infection involves a large initial expansion in the numbers of responding cells, accompanied by differentiation of these cells. Expression of the adhesion molecule CD62L is high on naïve cells and rapidly downregulated on the surface of the majority (～90%) of cells during the ‘effector’ phase of acute infection. Adoptive transfer studies have been used to study differentiation in this system; however, relatively little work has investigated the phenotype of cells in the endogenous repertoire. We demonstrate that the extent of CD62L down‐regulation is positively correlated with clone size in vivo, consistent with division‐linked differentiation of responding cells. Other features of the endogenous CD62L^hi and CD62L^lo repertoire are that the CD62L^lo repertoire is less diverse than the CD62L^hi repertoire and represents a subset of clonotypes found in the CD62L^hi repertoire. To test whether these observations are compatible with a mechanism of division‐linked differentiation, we developed a mathematical model, where there is a probability of CD62L down‐regulation associated with cell division. Comparison of model results with experimental data suggests that division‐linked differentiation provides a simple mechanism to explain the relationship between clone size and phenotype of CD8⁺ T cells during acute infection.     

Light regulation of retinal dopamine that is independent of melanopsin phototransduction

Light-dependent release of dopamine (DA) in the retina is an important component of light-adaptation mechanisms. Melanopsin-containing inner retinal photoreceptors have been shown to make physical contacts with DA amacrine cells, and have been implicated in the regulation of the local retinal environment in both physiological and anatomical studies. Here we determined whether they contribute to photic regulation of DA in the retina as assayed by the ratio of DA with its primary metabolite, 3,4-dihydroxyphenylacetic acid (DOPAC), and by c-fos induction in tyrosine hydroxylase (TH)-labelled DA amacrine cells. Light treatment (∼0.7 log W/m² for 90 min) resulted in a substantial increase in DA release (as revealed by an increase in the DOPAC : DA ratio), as well as widespread induction of nuclear c-fos in DA amacrine cells in wild-type mice and in mice lacking melanopsin ( Opn4 ^−/− ). Light-induced DA release was also retained in mice lacking rod phototransduction (Gnat1 ^−/− ), although the magnitude of this response was substantially reduced compared with wild-types, as was the incidence of light-dependent nuclear c-fos in DAergic amacrines. By contrast, the DAergic system of mice lacking both rods and cones ( rd/rd cl ) showed no detectable light response. Our data suggest that light regulation of DA, a pivotal retinal neuromodulator, originates primarily with rods and cones, and that melanopsin is neither necessary nor sufficient for this photoresponse.     

Functional properties and substrate characterization of human CYP26A1, CYP26B1, and CYP26C1 expressed by recombinant baculovirus in insect cells

Introduction

The cytochrome P450 CYP26 family of retinoic acid (RA) metabolizing enzymes, comprising CYP26A1, CYP26B1, and CYP26C1 is critical for establishing patterns of RA distribution during embryonic development and retinoid homeostasis in the adult. All three members of this family can metabolize all trans-RA. CYP26C1 has also been shown to efficiently metabolize the 9-cis isomer of RA.

Methods

We have co-expressed each of the CYP26 enzymes along with the NADPH-cytochrome P450 oxidoreductase using a baculovirus/Sf9 insect cell expression system to determine the enzymatic activities of these enzymes in cell free preparations and have established an in vitro binding assay to permit comparison of binding affinities of the three CYP26 enzymes.

Results

We demonstrated that the expressed enzymes can efficiently coordinate heme, as verified by spectral-difference analysis. All CYP26s efficiently metabolized all-trans-RA to polar aqueous-soluble metabolites, and in competition experiments exhibited IC₅₀ values of 16, 27, and 15 nM for CYP26A1, B1, and C1 respectively for all-trans-RA. Furthermore, this metabolism was blocked with the CYP inhibitor ketoconazole. CYP26C1 metabolism of all trans-RA could also be effectively competed with 9-cis RA, with IC₅₀ of 62 nM, and was sensitive to ketoconazole inhibition.

Discussion

CYP26 enzymes are functionally expressed in microsomal fractions of insect cells and stably bind radiolabeled RA isomers with affinities respecting their substrate specificities. We demonstrated that compared to CYP26A and CYP26B, only CYP26C1 was able to bind with high affinity to 9-cis-RA. These assays will be useful for the screening of synthetic substrates and inhibitors of CYP26 enzymes and may be applicable to other cytochrome P450s and their respective substrates.     

International pharmaceutical social risk regulation: An ethical perspective

Pharmaceutical production and distribution constitute big business. For the companies the rewards can be substantial. Rates of return on drug company investments tend to be higher than many other manufacturing enterprises. But reward is only one side of the story. There is also the issue of social risk, the focus of this article. Social risk for pharmaceutical production is especially pronounced. An ineffective or, worse, dangerous drug, can have dire consequences for the population at large. For this reason, there is elaborate government regulation and oversight of drug safety and risk. These systems, especially in the US and Europe, will be the main focus of this paper. The two systems will be described, and then compared and contrasted in terms of their framing of social risk and actions governments take to limit it. Systems elsewhere, especially in the developing world, are increasing in relative importance and these will be briefly discussed as well. Ethical issues that have arisen in these various systems will be surfaced and analysed. The paper will close with some conclusions and suggestions for further research.