A transgenic approach to identify thyroxine transporter-expressing structures in brain development

Transporters are essential in thyroid hormone metabolism. Thyroxine (T4) is transported by solute carrier organic anion transporter 1c1 (SLCO1C1, OATP14) into the adult brain, where T4 is converted to 3,5,3'-triiodothyronine (T3). In adults, SLCO1C1 expression is found in two brain barrier structures: the blood-brain barrier (BBB) and choroid plexus. However, little is known about how T4 is transported in the developing brain, when the BBB is not yet completely formed. We employed bacterial artificial chromosome recombineering to generate transgenic mice carrying Cre recombinase in the Slco1c1 locus (Slco1c1-Cre mice). In Slco1c1-Cre mice Cre was expressed at the sites that have been previously reported for SLCO1C1 in adults. To trace Cre expression during development, we crossed Slco1c1-Cre transgenic mice with Rosa26 reporter mice. β-galactosidase staining showed Cre activity in neurones of various brain structures, such as cortical layer 2/3 and the hippocampus, suggesting transient Slco1c1 expression during brain development. At embryonic day15, SLCO1C1 was expressed at the same site as TBR2, a marker of neuronal progenitors. Neurones that express SLCO1C1 during their development could be T4 sensitive. In support of this hypothesis, hypothyroxinaemia induced by propylthiouracil treatment of dams decreased the number of β-galactosidase-positive neurones in cortical layer 2/3 of newborn Slco1c1-Cre/Rosa26 mice. In conclusion, by generating Slco1c1-Cre transgenic mice, we demonstrated that SLCO1C1 is expressed in the neuronal cell lineage during brain development. Expression of SLCO1C1 may underlie the extraordinary sensitivity of specific neuronal populations to hypothyroxinaemia.

A randomized cross-over trial comparing single-agents capecitabine (C) and UFT plus leucovorin (LV) in patients (Pts) with advanced colorectal cancer (CRC): Preliminary data of a patient preference study

558

Background: Oral fluoropyrimidines such as C and UFT plus LV (U) are widely used pro-drugs dedicated to the care of CRC. Although their toxicity profile may slightly differ, no direct comparison between these treatments has been done as both molecules are converted into fluorouracil. To help the physicians to choose between C and U, we initiated this randomized cross-over trial aimed to assess patient's preference.

Methods: Pts with advanced CRC received either a first cycle of C (1,250mg/m2 x 2/d for 14 days, q3 wks) or a first cycle of U (UFT 300mg/m2/d plus LV 75 mg/d in 3 divided doses every 8 hrs for 28 days, repeated at 35-day intervals). Patients were randomized to receive C at cycle 1 followed by U (arm A) or U at cycle 1 followed by C (arm B). After 2 cycles, pts were asked which treatment they preferred. Treatment was then continued with the chosen regimen. Preferences rates are presented with 95% confidence intervals and the two groups are compared with the chi-squared test.

Results: 89 pts were enrolled from 10/2005 to 6/2010. Treatment arms were well balanced for baseline characteristics: male 57%; median age 66 years; PS 0-1 81%. Most of the pts were heavily pretreated (0/1/2/ and >2 previous chemotherapy lines: 6/2/15/66). 64 (arm A: 35, arm B: 29)/89 pts received at least 2 cycles of chemotherapy and were evaluable for preference. At cycle 1, 21% and 43% of the pts presented at least 1 severe toxic event with C and U, respectively. Pts with U at cycle 1 presented more likely with severe fatigue and anorexia. There was 1 toxic death under C (gr. 3 diarrhea, gr.4 neutropenia) at cycle 1. Overall, 66% (95%CI: 52-77%) of evaluable pts expressed preference for C, and there was a statistically significant difference between arms A and B (p<0.02) with more pts preferring C in arm A: 79% (95%CI: 61-91%), as compared to arm B: 50% (95%CI: 31-79%).

Conclusions: Pts with advanced CRC preferred C over U, especially when given during the first cycle.

No significant financial relationships to disclose.

Mineralocorticoid receptors in control of emotional arousal and fear memory

The stress hormone corticosterone acts via two receptor types in the brain: the mineralocorticoid (MR) and the glucocorticoid receptor (GR). Both receptors are involved in processing of stressful events. A disbalance of MR:GR functions is thought to promote stress-related disorders. Here we studied the effect of stress on emotional and cognitive behaviors in mice with forebrain-specific inactivation of the MR gene (MR(CaMKCre), 4 months old; and control littermates). MR(CaMKCre) mice responded to prior stress (5 min of restraint) with higher arousal and less locomotor activity in an exploration task. A fear conditioning paradigm allowed assessing in one experimental procedure both context- and cue-related fear. During conditioning, MR(CaMKCre) mice expressed more cue-related freezing. During memory test, contextual freezing remained potentiated, while control mice distinguished between cue (more freezing) and context episodes (less freezing) in the second memory test. At this time, plasma corticosterone levels of MR(CaMKCre) mice were 40% higher than in controls. We conclude that control of emotional arousal and adaptive behaviors is lost in the absence of forebrain MR, and thus, anxiety-related responses are and remain augmented. We propose that such a disbalance in MR:GR functions in MR(CaMKCre) mice provides the conditions for an animal model for anxiety-related disorders.

Cell cycle arrest and aberration yield in normal human fibroblasts. I. Effects of X‐rays and 195 MeV u−1C ions

PURPOSE

To examine the relationship between cell proliferation and the expression of chromosomal damage in normal human skin fibroblasts after X-ray and particle irradiation.

MATERIALS AND METHODS

Confluent G0/G1 AG1522B cells were exposed to X-rays or 195MeV u(-1) C ions with a linear energy transfer of 16.6 keV microm(-1) in the dose range 1-4 Gy. Directly after irradiation, cells were reseeded at a low density in medium containing 5-bromo-2'-deoxyuridine. At multiple time points post-irradiation, the cumulative BrdU-labelling index, mitotic index and aberration frequency were measured. Based on these data, the total amount of damage induced within the entire cell population was estimated by means of mathematical analysis.

RESULTS

Both types of radiation exposure exert a pronounced effect on the cell cycle progression of fibroblasts. They result in delayed entry of cells into S-phase and into the first mitosis, and cause a dramatic reduction in mitotic activity. Measurement of chromosomal damage in first-cycle cells at multiple time points post-irradiation shows that the frequencies of aberrant cells and aberrations increase with time up to twofold for the lower doses. However, for the higher doses, this effect is less pronounced or even disappears. When the data for the whole cell population are analysed, it becomes evident that only a few damaged fibroblasts can progress to the first mitosis, a response attributable at least in part to a long-term arrest of injured cells in the initial G0/G1-phase. As observed in other investigations, the effectiveness of 195 MeV u(-1) C ions was similar or slightly higher than X-rays for all endpoints studied leading to a relative biological effectiveness in the range 1.0-1.4.

CONCLUSIONS

Cell cycle arrests affect the aberration yield observable in normal human fibroblasts at mitosis. The data obtained for the cell population as a whole reveal that injured cells are rapidly removed from the mitotically active population through a chronic cell cycle arrest, which is consistent with other studies that indicate that this response is a specific strategy of fibroblasts to minimize the fixation and propagation of genetic alterations.

Effect of the epidermal growth factor receptor antibody panitumumab on triggering of ADCC

11055

Targeted therapy against the epidermal growth factor receptor (EGF-R) has been introduced into clinical practice for several solid tumors. Thus far, EGF-R- directed antibodies have received approval for the treatment of advanced colorectal and head and neck cancer. Recent studies demonstrated an association between Fcg receptor polymorphisms and clinical outcome. Here, we investigated effector mechanisms of the human IgG2 antibody pantitumumab and zalutumumab—a human IgG1 antibody against EGF-R, currently in phase III clinical evaluation. Both antibodies had similar binding characteristics, but differed in induction of antibody- dependent cellular cytotoxicity (ADCC). Zalutumumab induced potent MNC-mediated ADCC via FcgRIII (CD16), which was poorly triggered by panitumumab. Interestingly, not only zalutumumab but also panitumumab recruited neutrophils for ADCC. Neutrophil- mediated killing is triggered via FcgRIIa (CD32), and is potentially affected by its 131R/H polymorphism. Thus, panitumumab- mediated ADCC was more effective by neutrophils from FcgRIIa-131H homozygous individuals than from -131R individuals. ADCC induced by the IgG1 antibody zalutumumab was not affected by this polymorphism. In an experimental metastasis model in mice, both zalutumumab and panitumumab prevented establishment of metastases at low antibody concentrations which allowed the induction of ADCC but not the inhibition of signalling. Our results may implicate neutrophil- mediated ADCC in the in vivo mechanisms of action of EGF-R- directed antibodies, and suggest that heterogeneity in clinical responses due to the FcgRIIa-131R/H polymorphism can be expected for panitumumab.

[Table: see text]

Transparent TiO2 nanotube electrodes via thin layer anodization: fabrication and use in electrochromic devices

In the present work, we describe an anodization process that is able to fully transform a thin Ti metal layer on a conductive glass into a TiO(2) nanotubular array. Under optimized conditions, nanotube electrodes can be obtained that are completely transparent and defect-free and allow electrochromic switching. These electrochromic electrodes show remarkable properties and can be directly integrated into devices.

The efficiency of nanotube formation on titanium anodized under voltage and current control in fluoride/glycerol electrolyte

The formation of nanotubes on titanium is compared for anodizing under controlled voltage and controlled current in a fluoride/glycerol electrolyte. Rutherford backscattering spectroscopy and nuclear reaction analysis are employed to determine the film compositions. Film morphologies are examined by electron microscopy. The findings reveal films of approximate composition TiO(2).0.15TiF(4) that probably also contain derivatives of glycerol. Controlled voltage conditions resulted in more uniform final nanotube dimensions, for a particular charge density, and the highest efficiency of film growth, with the charge of the titanium in the film representing ∼48% of the charge passed during anodizing. Under current control, the efficiency decreased from ∼40% to ∼23% with increase of the current density from 0.1 to 0.5 mA cm(-2). Further, the thickness of the barrier layer was sometimes enhanced under current control, possibly due to a non-uniform current distribution and consequently elevated local temperature.

Deleterious role of TNF-alpha in retinal ischemia-reperfusion injury

PURPOSE

Tumor necrosis factor (TNF)-alpha is a mediator of neuronal cell death and survival in ischemia-reperfusion injury. This study was conducted to further elucidate the role of TNF-alpha and its receptor in an in vivo model of retinal ischemia-reperfusion injury by investigating its effects on retinal histopathology and function.

METHODS

Retinal ischemia-reperfusion injury was performed on p55 and p75 knockout (KO) mice and Sprague-Dawley rats using the high intraocular pressure

METHOD

The temporal expression of TNF-alpha was ascertained with immunohistochemical staining. Separate rats received intravitreal recombinant TNF-alpha or neutralizing antibody before or after ischemia. TUNEL labeling was performed to assess for cell death, and electroretinography was performed to assess function.

RESULTS

TNF-alpha expression peaked at 12 to 24 hours after ischemia-reperfusion injury. TUNEL staining was diminished after intravitreal TNF-alpha antibody. Both transgenic KOs demonstrated significantly less functional impairment. Rats receiving recombinant TNF-alpha 48 hours after ischemia showed exaggerated functional impairment. Animals treated with TNF-alpha antibody before ischemia displayed significant functional improvement.

CONCLUSIONS

TNF-alpha plays a largely deleterious role in ischemia-reperfusion injury in an in vivo model of retinal injury. Direct neutralization of this cytokine partially preserves retinal function. The diverse characteristics of TNF-alpha are attributed in part to the timing of its expression after injury. TNF-alpha receptor expression and function, along with combination treatments targeting death receptor-mediated apoptosis, should be further explored to develop neuroprotective therapeutic strategies for acute retinal ischemic disorders.

Genetic dissection of glucocorticoid receptor function in the mouse brain

In the brain, glucocorticoids exert functions in neurogenesis, synaptic plasticity and behavioural responses, as well as in the control of hypothalamic-pituitary-adrenal axis activity. The generation of mice harbouring germline mutations that result either in loss or in gain of glucocorticoid receptor function provided a useful tool for understanding the role of glucocorticoids in the brain in vivo. The improvement of genomic technologies additionally allowed the establishment of mouse models with function-selective point mutations of the receptor as well as the generation of mice harbouring spatially and/or temporally restricted loss of glucocorticoid receptor, specifically within the brain. These models will provide the opportunity to better understand the mechanisms involved in glucocorticoid signalling within the nervous system.

Medical management of the failing Fontan

The Fontan operation accomplishes complete separation of systemic venous blood from pulmonary venous circulation in patients with single ventricle anatomy. Operative survival since the first description of the Fontan operation is excellent in the current era through modifications in surgical techniques, identification of patient-specific risk factors, and advances in postoperative care. Improved early outcomes have also resulted in a decline in late mortality for patients who have undergone staged palliation with the Fontan operation. As the number of late survivors from the Fontan operation increases, caregivers will be evermore faced with the challenge of recognizing and managing the patient with failing Fontan physiology. Even after excellent early results, patients with single ventricle lesions remain at risk of progressive ventricular dysfunction, dysrhythmias, progressive hypoxemia, elevated pulmonary vascular resistance, and protein-losing enteropathy, which can result in morbidities including but not limited to, myocardial failure, thromboembolism, and stroke. Consequently, continued long-term survival of patients who undergo the Fontan operation is dependent upon preservation of single ventricle function, avoidance of late complications, and, in the patient with a failing Fontan, recognition and treatment of the underlying pathophysiologic process that has resulted in Fontan failure.