Ecotoxicology of mercury concentrations in arctic lamprey (Lethenteron camtschaticum)

Arctic lamprey (Lethenteron camtschaticum) is an important dietary resource for rural and indigenous communities in parts of Alaska, with some commercial use. As with many fish species harvested for human consumption, there are concerns regarding mercury concentrations ([Hg]) in Arctic lamprey that may impact human health. To date, information regarding the life cycle and diet of Arctic lamprey is scarce, with no published studies examining [Hg] in Arctic lamprey tissues. Our goals were to investigate the feeding ecology of Arctic lamprey from the Bering Sea, determine how diet and potential dietary shifts might influence [Hg] in muscle, and determine if current [Hg] may pose a human health risk. The mean total [Hg] in Arctic lamprey muscle (n = 98) was 19 ng/g wet-weight. Log transformed total [Hg] were not associated with any measured biological variables including length, mass, δ13C values, or δ15N values. A stable isotope mixing model estimated that capelin (Mallotus villosus) accounted for 40.0 ± 4.0% of the Arctic lamprey diet, while Pacific sand lance (Ammodytes hexapterus) and Pacific herring (Clupea pallasii) accounted for 37.8 ± 3.1% and 22.2 ± 3.5% respectively. Finally, diet percentage compositions shifted based on size class (i.e., medium versus large). These results indicated that feeding location, bioaccumulation, and biomagnification are not important drivers of [Hg] in Arctic lamprey and current [Hg] do not pose a human health risk. Taken together, this research further expands our knowledge of Arctic lamprey trophic ecology in the eastern Bering Sea.

[Adjuvant chemotherapy in hormone-receptor positive HER2-negative early breast cancer]

Adjuvant treatment in hormone-receptor positive, HER2-negative early breast cancer is controversial. Chemotherapy benefit in this subset of patients is generally small, and a wide variability exists among dif-ferent subgroups of patients, depending on various patient and tumor characteristics. To select subsets of patients who will really benefit from chemotherapy, one of the possible strategy is based on multigene expression analysis. This approach is providing deeper insights into the biological heterogeneity of breast cancer, allowing to further sub-divide hormone-receptor positive tumors into groups, with different clinical behavior and response to treatments. Among less expensive and better validated methods, high levels of Ki67, a routinely assessed immunohistochemical marker of cell proliferation, can suggest the use of chemotherapy in this subset of patients. Generally, regimen used should include a taxane. In fact, retrospective analyses of clinical trials suggest that anthracyclines may be less active in hormone-receptor positive HER2-negative patients, while several other trials and meta-analyses involving taxanes, showed a benefit in terms of risk of relapse and death reduction. Among taxanes, docetaxel should be preferred because of a better therapeutic index, and a higher activity in comparison to paclitaxel. At present, reliable and accurate evaluation of histopathological and immunohistochemical factors may allow the choice of omitting adjuvant chemotherapy in patients with low risk hormone receptor positive HER2-negative breast cancer. Uncertainty still exists about chemotherapy benefit for a substantial proportion of women of this subgroup. Nevertheless, the addition of taxanes, mainly docetaxel, to anthracyclines, seems to overcome the relative chemoresistance of hormone-receptor positive tumors, providing a benefit in disease free survival and overall survival.

Recent advances in the adjuvant treatment of early breast cancer

The majority of breast cancers are actually diagnosed at an early stage. Selection of the best treatment in the adjuvant setting represents a paramount step to reduce the risk of recurrence and cancer-specific mortality. At the present time decision making is based on individualized risk assessment, that takes into account patient and tumor clinical-pathological characteristics. New available tools, such as gene expression profiling, offer the potential to provide accurate prognostic and predictive information, but they require further validation. The present article provides an overview of current strategies in adjuvant breast cancer setting, and addresses a number of unresolved questions related to the role of taxanes, trastuzumab and hormonal treatment.

Docetaxel in the adjuvant therapy of HER-2 positive breast cancer patients

Considering the clinical benefit of trastuzumab in advanced breast cancer, fi ve prospective adjuvant randomized trials have recently been completed and early results have been published. Two of them, (NSABP-B31 and NCCTG N9831), employed anthracycline-containing regimens with sequential paclitaxel, with or without trastuzumab. The third study, HERA trial, randomized patients after adjuvant chemotherapy into an observational arm, one or two years of trastuzumab. Results of these studies, after a median follow up of 2-3 years confirm a DFS and OS benefit for the experimental arms. The worst rate of cardiotoxicity, in terms of incidence of CHF, with the use of trastuzumab and anthracycline based regimens was 4.1% in the trastuzumab arm of the NSABP-B31 trial. Among the fi ve trastuzumab trials, two, BCIRG 006 and FinHer, employed docetaxel-based regimens. The innovative BCIRG 006 trial compared ACdocetaxel (T) with two trastuzumab-containing regimens, ACTH, and a non-anthracycline-containing regimens, TCH, with a clear advantage in DFS for both trastuzumab arms. Data from the second interim analysis indicate that, in the subgroup of patients without co-amplification of topoisomerase 2 (TOPO-2), the arm without trastuzumab (ACT) showed a DFS significantly poorer that in the other arms; moreover, if we consider the lower toxicity of TCH regimen in comparison with anthracycline-containing arms, the innovative statements offered by BCIRG 006 trial appear evident, and these findings opened an important question about the consolidated employment of anthracyclines in adjuvant setting.The FinHer trial was a small trial testing a short course of trastuzumab (9 weeks) concomitantly with a chemotherapy including docetaxel, and there was a significant advantage in DFS for the trastuzumab based arms, without relevant toxicity and without any cardiotoxicity. Although data from all trastuzumab adjuvant trials, and without particulary from BCIRG-006 and FinHer trials, appear very intriguing, further follow-up is required.

Optimal sequence of anthracyclines and taxanes as adjuvant breast cancer treatment

Results from randomized trials evaluating taxane versus non-taxane containing regimens in adjuvant breast cancer treatment indicate an advantage in DFS and OS for the taxane-arms, but the best schedule of administration, in combination with anthracyclines or in sequence, is still a debated issue, even if the sequential strategy appears to be less toxic. Up to now, the majority of clinical trials employed the "standard" sequence, with anthracycline-based combinations fi rst, followed by taxanes. Few small phase II trials evaluated the reverse sequence, with taxanes administered fi rst, most of them in metastatic or neoadjuvant setting, suggesting efficacy and lower toxicity. An important issue to be considered is the hypothesized differences in the ability of the drugs to induce cross-resistance to each other, as suggested by data of a preclinical study, and from clinical study with a cross-over design; results of these trials suggest that the best strategy would be to administer a taxane prior to an anthracycline, also according to the Norton and Simon hypothesis. Moreover, trials evaluating the best sequence of anthracyclines and taxanes in adjuvant breast cancer setting are of small sample size, and an adequately powered randomized phase III trial is needed before definitive conclusions are reached.

The presence of arginine vasopressin and its mRNA in rat choroid plexus epithelium

Arginine vasopressin (AVP) plays an important role in the regulation of secretory function and hemodynamics of choroid plexus, the primary site of cerebrospinal fluid (CSF) production. In the present study, localization of AVP and its transcripts in choroid plexus of adult male Sprague-Dawley rats was studied by immunohistochemistry and in situ hybridization histochemistry, respectively. For immunohistochemical analysis, AVP-specific polyclonal rabbit antibody was employed. Plasmid, pGrVP, containing a 232-bp fragment of rat AVP cDNA encoding the C-terminus of proAVP, was used as a probe to detect AVP mRNA. AVP-immunoreactive product was predominantly localized close to the apical (CSF-facing) membrane of choroidal epithelium while AVP transcripts were distributed throughout the cytoplasm of the cells. Our findings indicate that AVP is synthesized in choroid plexus epithelium, which suggests autocrine and/or paracrine actions of this peptide in choroidal tissue.

Immunohistochemical localization of nitric oxide synthase in rat anterior choroidal artery, stromal blood microvessels, and choroid plexus epithelial cells

Nitric oxide (NO) has recently been shown to regulate blood flow to choroid plexus, a specialized brain structure responsible for production of most of cerebrospinal fluid. In the present study, we used a specific polyclonal rabbit antibody against the neuronal isoform of NO synthase (NOS), a synthetic enzyme for NO, to determine the localization of NOS in the choroid plexus of adult male Sprague-Dawley rats. NOS-containing nerve fibers were found in the anterior choroidal artery and its branches, and in stromal blood microvessels. Chronic denervation experiments indicated that these nerve fibers originate predominantly from the sphenopalatine ganglion. NOS-immunopositive staining was also detected in the cytoplasm of choroidal epithelial cells. NADPH-diaphorase, a histochemical marker for NOS, was found to colocalize with NOS-immunoreactive product in both nerve fibers and choroidal epithelium. Both neuronal and epithelium-derived NO may regulate secretory function and hemodynamics of choroidal tissue.